TOEFL TPO
L1C1
"Listen to part of a conversation between a student and a librarian.Hi, um... I really hope you can help me.
That's why I'm here.
What can I do for you?
I'm supposed to do a literature review for my psychology course, but I'm having a hard time finding articles.
I don't even know where to start looking.
You said this is for your psychology course, right?
So your focus is on...
Dream Interpretation.
Well, you have a focus, so that's already a good start.
Hmmm... well, there're a few things... oh wait... have you checked to see if your professor put any materials for you to look at on reserve?
Aha, that's one thing I did know to do.
I just copied an article, but I still need three more on my topic from three different journals.
Let's get you going on looking for those then.
We have printed versions of twenty or so psychology journals in the Reference Section.
These are ones published within the last year.
Now that I think about it... there's a journal named Sleep and Dreams.
Oh, yeah, the article I just copied is from that journal, so I've got to look at other sources.
Ok, actually, most of our materials are available electronically now.
You can access psychology databases or electronic journals and articles through the library's computers.
And if you want to search by title with the word ""dream"" for example, just type it in and all the articles with 'dream' in the title will come up on the screen.
Cool, that's great!
Too bad i can't do this from home.
But you can.
All of the library's databases and electronic sources can be accessed through any computer connected to the university network.
Really?! I can't believe I didn't know that.
It still sounds like it's gonna take a while though, you know, going through all of that information, all of those sources.
Maybe, but you already narrowed your search down to articles on Dream Interpretation, so it shouldn't be too bad.
And you probably notice that there's an abstract or summary at the top of the first page of the article you copied.
When you go into the databases and electronic sources, you have the option to display the abstracts on the computer screen, skimming those to decide whether or not you want to read the whole article should cut down some time.
Right, abstracts! They'll definitely make the project more doable.
I guess I should try out the electronic search while I'm still here then, you know, just in case.
Sure, er... that computer is free over there, and I'll be here till five this afternoon.
Thanks, I feel a lot better about this assignment now. "
L1L1
"Listen to part of a lecture in a contemporary art class.Ok, I'm going to begin this lecture by giving you your next assignment.
Remember I said that at some point during this semester I wanted you to attend an exhibit at the Fairy Street Gallery and then write about it?
Well, the exhibit that I want you to attend is coming up.
It's already started in fact, but it'll be at the gallery for the next month, which should give you plenty of time to complete this assignment.
The name of the artist exhibiting there is Rose Frantzen.
Frantzen's work may be unfamiliar to you since she's a relatively young artist.
But she's got a very unusual style, compared to some of the artists we've looked at this term.
But anyway, Frantzen's style is what she herself calls Realistic Impressionism.
So you've probably studied both of these movements separately, separate movements, Realism and Impressionism, in some of your art history courses.
So who can just sum these up?
Well, Impressionism started in the late 19th century.
Um... the basic impressionist style was very different from earlier styles.
It didn't depict scenes or models exactly as they looked.
Um... Impressionist painters tended to apply paint really thickly, and in big brushstrokes, so the texture of the canvas was rough.
Good.What else?What were the subjects?
Well, a lot of impressionist artists painted everyday scenes, like people on the streets and in cafes, uh, lots of nature scenes, especially landscapes.
Good.So when you go to the exhibit, I really want you to take a close look at a certain painting.
It's a farm scene.
And you will see it right as you enter the gallery.
The reason I think this painting is so important is that it stresses the impressionist aspect of Frantzen's style.
It's an outdoor scene, an everyday scene.
It's kind of bleak, which you can really see those broad brushstrokes and the blurry lines.
The colors aren't quite realistic.
The sky is kind of, well an unnatural pinkish yellow.
And the fence in the foreground is blue, but somehow the overall scene gives an impression of a cold, bleak winter day on a farm.
So that's the impressionist side of her work.
Oh, and speaking about farms, that reminds me.
One interesting thing I read about Frantzen is that when she first moved back to Iowa after living abroad, she often visited this place in her town called the Sales Barn.
And the Sales Barn, it was basically this place where the local farmers bought and sold their cattle, their farm animals.
And the reason Frantzen went there, and she later on would visit other places like dance halls, was to observe people and the ways that they moved.
She really found that this helped her work - that it gave her an understanding of body movements and actions, how humans move, and stand still, what their postures were like, too.
So, what about Realism?
What are the elements of Realism we should be looking for in Frantzen's work?
Um... real honest depictions of subject matter, pretty unidealized stuff, and pretty everyday subject matter, too.
Good. One other painting I really want you to look at is of a young woman surrounded by pumpkins.
You will notice that the woman's face is so realistic looking that it's almost like a photograph.
The woman's nose is a little less than perfect and her hair is kind of messed up.
This is realism.
But then, the background of the painting, this woman with the pumpkins is wrapped in a blanket of broad thick brushstrokes, and, it's all kinds of zigzagging brushstrokes and lines, kind of chaotic almost when you look at it close.
And there are vibrant colors.
There's lots of orange, with little hints of an electric blue peeking out.
I find Frantzen to be a very accessible artist.
I mean, some artists, to appreciate them, you have to know their life story.
But here's a little bit about Rose Frantzen's life anyway.
She attended art school, but was told by one of her instructors that she wasn't good at illustration, that she should go into advertising instead.
So she took advertising classes and fine arts classes too, until she was convinced by the head of an advertising agency that her work was really good, that she could be an artist.
But of course, it's not as easy as that, and so Frantzen had to paint other people's portraits at places like art fairs just to make money to buy paint for her more serious art work.
No matter what, she never stopped painting.
And now, Frantzen is doing extremely well.
And her work is being shown all over the country.
So I think most of us would be discouraged if we had to face challenges and difficulties like that.
But what's important is that you keep at it that you don't give up.
That's what is really important to remember. "
L1L2
"Listen to part of a lecture in a geology class.Ok, let's get started. Great.
Today I want to talk about a way in which we are able to determine how old a piece of land, or some other geologic feature is - dating techniques.
I'm gonna to talk about a particular dating technique.
Why? Good dating is key to good analysis.
In other words, if you want to know how a land formation was formed, the first thing you probably want to know is how old it is.
It's fundamental.
Uh... Take the Grand Canyon for instance.
Now, we geologists thought we had a pretty good idea of how the Grand Canyon in the southwestern United States was formed.
We knew that it was formed from sandstone that solidified somewhere between 150 and 300 million years ago.
Before it solidified, it was just regular sand.
Essentially it was part of a vast desert.
And until just recently, most of us thought the sand had come from an ancient mountain range fairly close by that flattened out over time.
That's been the conventional wisdom among geologists for quite some time.
But now we've learned something different, and quite surprising, using a technique called Uranium-Lead Dating.
I should say that Uranium-Lead Dating has been around for quite a while.
But there have been some recent refinements.
I'll get into this in a minute.
Anyway, Uranium-Lead Dating has produced some surprises.
Two geologists discovered that about half of the sand from the Grand Canyon was actually once part of the Appalachian Mountains.
That's really eye-opening news, since the Appalachian Mountain Range is, of course, thousands of kilometers to the east of the Grand Canyon.
Sounds pretty unbelievable, right?
Of course, the obvious question is how did that sand end up so far west?
The theory is that huge rivers and wind carried the sand west where it mixed in with the sand that was already there.
Well, this was a pretty revolutionary finding.
Um... and it was basically because of Uranium-Lead Dating.
Why? Well, as everyone in this class should know, we usually look at the grain type within sandstone, meaning the actual particles in the sandstone, to determine where it came from.
You can do other things too, like look at the wind or water that brought the grains to their location and figure out which way it was flowing.
But that's only useful up to a point, and that's not what these two geologists did.
Uranium-Lead Dating allowed them to go about it in an entirely different way.
What they did was: they looked at the grains of Zircon in the sandstone.
Zircon is a material that contains radioactive Uranium, which makes it very useful for dating purposes.
Zircon starts off as molten magma, the hot lava from volcanoes.
This magma then crystallizes.
And when Zircon crystallizes, the Uranium inside it begins to change into Lead.
So if you measure the amount of Lead in the Zircon grain, you can figure out when the grain was formed.
After that, you can determine the age of Zircon from different mountain ranges.
Once you do that, you can compare the age of the Zircon in the sandstone in your sample to the age of the Zircon in the mountains.
If the age of the Zircon matches the age of one of the mountain ranges, then it means the sandstone actually used to be part of that particular mountain range.
Is everybody with me on that?
Good. So, in this case, Uranium-Lead Dating was used to establish that half of the sandstone in the samples was formed at the same time the granite in the Appalachian Mountains was formed.
So because of this, this new way of doing Uranium-Lead Dating, we've been able to determine that one of our major assumptions about the Grand Canyon was wrong.
Like I said before, Uranium-Lead Dating has been with us for a while.
But, um... until recently, in order to do it, you really had to study many individual grains.
And it took a long time before you got results.
It just wasn't very efficient.
And it wasn't very accurate.
But technical advances have cut down on the number of grains you have to study, so you get your results faster.
So I'll predict that Uranium-Lead Dating is going to become an increasingly popular dating method.
There are a few pretty exciting possibilities for Uranium-Lead Dating.
Here is one that comes to mind.
You know the theory that earth's continents were once joined together and only split apart relatively recently?
Well, with Uranium-Lead Dating, we can prove that more conclusively.
If they show evidence of once having been joined, that could really tell us a lot about the early history of the planet's geology. "
L1C2
"Listen to part of a conversation between a student and his professor.Hi Mathew, I'm glad you could come in today.
You've been observing Mr. Grable's third-grade class for your approaches to education paper, right?
Um, yes. I go over to Johnson Elementary School, you know, to watch Mr. Grable teach the children in class.
It's been amazing, I mean, I'm just learning so much from just watching him.
I'm so glad the classroom observations are a requirement for the education program.
I mean it's like the best thing ever to prepare you to be a good teacher.
Well, I'm glad to see you feel that way, Mathew.
You know, that's the goal.
So, I've been reading over your observation notes and I'm quite interested in what's going on, in particular with the astronomy unit he's been teaching.
The astronomy unit?
It seems that Mr. Grable has mastered the interdisciplinary approach to teaching that we've been talking about in class.
Oh! OK, yeah, so like when he was teaching them astronomy, he didn't just teach them the names of the planets, he used it as a way to teach mythology.
Really! So, how did he do that?
Well, some of the students could already name the planets, but they didn't know that the names had any meaning - the stories behind them.
So, he...
He introduced Greek and Roman mythology as a way of explaining.
Like, you know, how like Jupiter's the biggest planet, right, and how Jupiter was the name of the king of the gods in Roman mythology, right?
So since Jupiter, the planet, is the largest planet in our solar system, it's like the king of the planets, like Jupiter was the king of all the gods.
Oh, Mathew, that's a great example.
Yeah! And each student chose a planet and then did research on it to write a report and make a presentation.
They went to the library to do the research, then they made presentations about the planet they chose.
So, in one science unit, in which the focus was astronomy, the students also learned about the literature of Greek and Roman mythology, used research skills in the library, wrote a report and practiced their oral presentation skills.
Exactly! He used this one topic to teach third-graders all that stuff - how to use the books in the library, to write reports, and even how to speak in public.
Plus they had a great time doing it.
You know, Mathew, this is just what we've been talking about in our class.
I'm sure everyone could learn something from your experience.
You know, Mathew, I'd love for you to talk about this astronomy unit in class on Wednesday.
Really?! Um... cause I don't really think I'll have any time to write my paper by then.
Oh, you won't need to write anything new just yet.
For Wednesday, use your class observation notes and explain the things we've discussed today.
Ok, that sounds all right. "
L1L3
"Listen to part of a lecture in an archaeology class.OK, we've been talking about early agriculture in the near east.
So let's concentrate on one site and see what we can learn from it.
Let's look at Catalhoyuk. Um... I'd better write that down. Catalhoyuk, that's about as close as we get in English.
It's Turkish, really.
The site's in modern day Turkey, and who knows what the original inhabitants called it.
Anyway, uh... Catalhoyuk wasn't the first agricultural settlement in the near east, but it was pretty early, settled about 9000 years ago in the Neolithic period.
And... um... the settlement... uh... town really, lasted about a thousand years and grew to a size of about eight or ten thousand people.
That certainly makes it one of the largest towns in the world at that time.
One of the things that makes the settlement of this size impressive is the time period.
It's the Neolithic, remember, the late Stone Age.
So the people that lived there had only stone tools, no metals.
So everything they accomplished, like building this town, they did with just stone, plus wood, bricks, that sort of thing.
But you got to remember that it wasn't just any stone they had, they had obsidian.
And um... obsidian is a black, volcanic, well, almost like glass.
It flakes very nicely into really sharp points.
The sharpest tools of the entire Stone Age were made of obsidian.
And uh... the people of Catalhoyuk got theirs from further inland, from central Turkey, traded for it, probably.
Anyway, what I wanna focus on is the way the town was built.
The houses are all rectangular, one storey, made of sun-dried bricks.
But what's really interesting is that there are no spaces between them, no streets in other words, and so generally no doors on the houses either.
People walked around on the roofs and entered the house through a hatchway on the roof, down a wooden ladder.
You can still see the diagonal marks of the ladders in the plaster on the inside walls.
Once you were in the house, there would be one main room and a couple of small rooms for storage.
The main room had the hearths, for cooking and for heat.
It would've been pretty cold during the winters.
And it also looks like they made their tools near the fire.
There tends to be a lot of obsidian flakes and chips in the hearth ashes, but no chimney.
The smoke just went out the same hatchway that people used for going in and out themselves.
So there would have been an open fire inside the house with only one hole in the roof to let the smoke out.
You and I would have found it a bit too smoky in there.
You can see on the walls, which they plastered and decorated with paintings.
They ended up with a layer of black soot on them, and so did people's lungs.
The bones found in the graves show a layer of soot on the inside of the ribs.
And that's another unusual feature of Catalhoyuk, the burial sites.
The graves have all been found under the houses, right under the floors.
And it may be this burial custom that explains why the houses were packed in so tightly without streets.
I mean, you might think it was for protection or something, but there has been no evidence found yet of any violent attack that would indicate that kind of danger.
It may be they wanted to live as near as possible to their ancestors' graves and be buried near them themselves.
But it makes a good point.
Based on excavations, we can know the layout of the houses and the location of the graves, but we're only guessing when we tried to say why they did it that way.
That's the way it is with archeology.
You are dealing with the physical remains that people left behind.
We have no sure access to what they thought and how they felt about things.
I mean it's interesting to speculate.
And the physical artifacts can give us clues, but there is a lot we can't really know.
So, for instance, their art.
They painted on the plastered walls and usually they painted hunting scenes with wild animals in them.
Now they did hunt and they also raised cereal crops and kept sheep, but we don't know why so many of the paintings are of hunting scenes.
Was it supposed to have religious or magical significance?
That's the kind of thing we can only guess at based on clues.
And hopefully, further excavation of Catalhoyuk will yield more clues.
But we'll probably never know for sure "
L1L4
"Listen to part of a lecture in a biology class.For today's discussion, we'll review the case study on how some animals have behaviorally adapted to their environments.
Now you had to read about two animal species, the Eastern marmot and the Olympic marmot.
Marmots are rodents.
They are large ground squirrels, about the size of an average house cat.
And they live in a variety of habitats.
And even though they spend the significant portion of the year hibernating, according to this case study, marmots are still considered excellent subjects for animal behavioral studies.
Why is that?
Well, when they are not hibernating, you can find them in open areas.
And they are pretty active during the day, which makes them easy to observe, right?
Uh-huh, so first let's discuss the Eastern marmots.
They reside throughout the eastern region of North America where there is a temperate climate, where the growing season lasts for at least five months of the year, which is when they do all their mating, playing and eating.
Oh, I see. At first I wasn't sure what growing season meant, just from the reading.
But now I get it.
It's the amount of time it takes for them to grow, right?
So it would be five months?
Umm? Oh, uh... I'm sorry but no.
It has nothing to do with that.
It's not about the time it takes for Eastern marmots to grow.
It's when the food is available.
That is when it's not covered in snow and there is no frost covering the grass and umm, vegetative parts of a plant's herbs and the flowers the marmots like to eat.
So growing season refers to the availability of the food they eat, OK?
So now how would you describe the Eastern marmots' social habits?
Well, they are really territorial, and loners, and just so aggressive even with other Eastern marmots.
And their mating ritual is just so impersonal.
Uh-huh?
Now when they emerge in the spring from hibernation, the mating process begins.
For them, well, they come together to mate and then they go their separate ways.
Then about six to eight weeks after birth, the offspring leave their mothers.
Really? Just six weeks?
Is that possible for the offspring to make it on their own so young?
Well, it's not as if they aren't ready for the real world because they are.
Remember, they mature quickly and the weather's nice.
Also they live in open fields where there is lots of edible vegetation.
So roughly six weeks after birth,
Eastern marmots are just old enough to take their chances of surviving in the temperate environment.
So how does this relate to their behavior?
Oh, I get it.
Since the climate's not too bad, the Eastern marmots don't have to rely on each other too much and they really don't need to stay together as a family to survive either.
Uh-huh. Any contrast, the Olympic marmots? What about them?
Well, they live together as a family and take care of their young until they are at least two years old.
They're really friendly with each other.
And what I really like is that they even have greeting ceremonies.
And they are not at all aggressive and territorial like the Eastern marmots.
So their social behavior is so different from Eastern marmots because of the climate where they live?
That seems so bizarre.
Well, the Olympic marmots inhabit meadows high in the Olympic Mountains where the weather conditions are much harsher.
So there is a lot more wind and snow.
The growing season only lasts about two to three months.
So in that much shorter period of time, all the Olympic marmots, male and female, eat, play, work and nurture the young together.
Because the climate is so harsh, cooperation increases the survival rate of the Olympic marmots.
They keep their young at home until they are physically able to survive on their own.
This could explain why the social behavior of the Olympic marmots is so unlike that of the Eastern marmots. "
L2C1
"Listen to a conversation between a student and a professor.Uh, excuse me, Professor Thompson.
I know your office hours are tomorrow, but I was wondering if you had a few minutes free now to discuss something.
Sure, John. What did you want to talk about?
Well, I have some quick questions about how to write up the research project I did this semester - about climate variations.
Oh, yes. You were looking at variations in climate in the Grant City area, right?
How far along have you gotten?
I've got all my data, so I'm starting to summarize it now, preparing graphs and stuff.
But I'm just... I'm looking at it and I'm afraid that it's not enough, but I'm not sure what else to put in the report.
I hear the same thing from every student.
You know, you have to remember now that you're the expert on what you've done.
So, think about what you'd need to include if you were going to explain your research project to someone with general or casual knowledge about the subject, like ... like your parents.
That's usually my rule of thumb: would my parents understand this?
OK. I get it.
I hope you can recognize by my saying that how much you do know about the subject.
Right. I understand.
I was wondering if I should also include the notes from the research journal you suggested I keep.
Yes, definitely.
You should use them to indicate what your evolution in thought was through time.
So, just set up, you know, what was the purpose of what you were doing - to try to understand the climate variability of this area - and what you did, and what your approach was.
OK. So, for example, I studied meteorological records; I looked at climate charts; I used different methods for analyzing the data, like certain statistical tests; and then I discussed the results.
Is that what you mean?
Yes, that's right. You should include all of that.
The statistical tests are especially important.
And also be sure you include a good reference section where all your published and unpublished data came from, 'cause you have a lot of unpublished climate data.
Hmm... something just came into my mind and went out the other side.
That happens to me a lot, so I've come up with a pretty good memory management tool.
I carry a little pad with me all the time and jot down questions or ideas that I don't want to forget.
For example, I went to the doctor with my daughter and her baby son last week and we knew we wouldn't remember everything we wanted to ask the doctor, so we actually made a list of five things we wanted answers to.
A notepad is a good idea.
Since I'm so busy now at the end of the semester, I'm getting pretty forgetful these days.
how can i just remembered what I was trying to say before.
Good. I was hoping you'd come up with it.
Yes. It ends up that I have data on more than just the immediate Grant City area, so I also included some regional data in the report.
With everything else it should be a pretty good indicator of the climate in this part of the state.
Sounds good. I'd be happy to look over a draft version before you hand in the final copy, if you wish.
Great. I'll plan to get you a draft of the paper by next Friday.
Thanks very much. Well, see ya.
OK. "
L2L1
"Listen to part of a psychology lecture. The professor is discussing behaviorism.Now, many people consider John Watson to be the founder of behaviorism.
And like other behaviorists, he believed that psychologists should study only the behaviors they can observe and measure.
They're not interested in mental processes.
While a person could describe his thoughts, no one else can see or hear them to verify the accuracy of his report.
But one thing you can observe is muscular habits.
What Watson did was to observe muscular habits because he viewed them as a manifestation of thinking.
What one kind of habits that he studied are laryngeal habits.
Watson thought laryngeal habits... you know, from larynx, in other words, related to the voice box... he thought those habits were an expression of thinking.
He argued that for very young children, thinking is really talking out loud to oneself because they talk out loud even if they're not trying to communicate with someone in particular.
As the individual matures, that overt talking to oneself becomes covert talking to oneself, but thinking still shows up as a laryngeal habit.
One of the bits of evidence that supports this is that when people are trying to solve a problem, they, um, typically have increased muscular activity in the throat region.
That is, if you put electrodes on the throat and measure muscle potential - muscle activity - you discover that when people are thinking, like if they're diligently trying to solve a problem, that there is muscular activity in the throat region.
So, Watson made the argument that problem solving, or thinking, can be defined as a set of behaviors - a set of responses - and in this case the response he observed was the throat activity.
That's what he means when he calls it a laryngeal habit.
Now, as I am thinking about what I am going to be saying, my muscles in my throat are responding.
So, thinking can be measured as muscle activity.
Now, the motor theory... yes?
Professor Blake, um, did he happen to look at people who sign?
I mean deaf people?
Uh, he did indeed, um, and to jump ahead, what one finds in deaf individuals who use sign language when they're given problems of various kinds, they have muscular changes in their hands when they are trying to solve a problem... muscle changes in the hand, just like the muscular changes going on in the throat region for speaking individuals.
So, for Watson, thinking is identical with the activity of muscles.
A related concept of thinking was developed by William James.
It's called ideomotor action.
Ideomotor action is an activity that occurs without our noticing it, without our being aware of it.
I'll give you one simple example.
If you think of locations, there tends to be eye movement that occurs with your thinking about that location.
In particular, from where we're sitting, imagine that you're asked to think of our university library.
Well, if you close your eyes and think of the library, and if you're sitting directly facing me, then according to this notion, your eyeballs will move slightly to the left, to your left, cause the library's in that general direction.
James and others said that this is an idea leading to a motor action, and that's why it's called ""ideomotor action"" - an idea leads to motor activity.
If you wish to impress your friends and relatives, you can change this simple process into a magic trick.
Ask people to do something such as I've just described: think of something on their left; think of something on their right.
You get them to think about two things on either side with their eyes closed, and you watch their eyes very carefully.
And if you do that, you'll discover that you can see rather clearly the eye movement - that is, you can see the movement of the eyeballs.
Now, then you say, think of either one and I'll tell you which you're thinking of.
OK. Well, Watson makes the assumption that muscular activity is equivalent to thinking.
But given everything we've been talking about here, one has to ask: are there alternatives to this motor theory - this claim that muscular activities are equivalent to thinking?
Is there anything else that might account for this change in muscular activity, other than saying that it is thinking?
And the answer is clearly yes.
Is there any way to answer the question definitively?
Now i think the answer is no. "
L2L2
"Listen to part of a lecture from a Botany class.Hi, everyone. Good to see you all today.
Actually, I expected the population to be a lot lower today.
It typically runs between 50 and 60 percent on the day the research paper is due.
Um, I was hoping to have your exams back today, but, uh, the situation was that I went away for the weekend, and I was supposed to get in yesterday at five, and I expected to fully complete all the exams by midnight or so, which is the time that I usually go to bed.
But my flight was delayed, and I ended up not getting in until one o'clock in the morning.
Anyway, I'll do my best to have them finished by the next time we meet.
OK. In the last class, we started talking about useful plant fibers.
In particular, we talked about cotton fibers, which we said were very useful, not only in the textile industry, but also in the chemical industry, and in the production of many products, such as plastics, paper, explosives, and so on.
Today we'll continue talking about useful fibers, and we'll begin with a fiber that's commonly known as ""Manila hemp"".
Now, for some strange reason, many people believe that Manila hemp is a hemp plant. But Manila hemp is not really hemp.
It's actually a member of the banana family - it even bears little banana-shaped fruits.
The ""Manila"" part of the name makes sense, because Manila hemp is produced chiefly in the Philippine Islands and, of course, the capital city of the Philippines is Manila.
Now, as fibers go, Manila hemp fibers are very long.
They can easily be several feet in length and they're also very strong, very flexible.
They have one more characteristic that's very important, and that is that they are exceptionally resistant to salt water.
And this combination of characteristics - long, strong, flexible, resistant to salt water - makes Manila hemp a great material for ropes, especially for ropes that are gonna be used on ocean-going ships.
In fact, by the early 1940's, even though steel cables were available, most ships in the United States Navy were not moored with steel cables; they were moored with Manila hemp ropes.
Now, why was that? Well, the main reason was that steel cables degrade very, very quickly in contact with salt water.
If you've ever been to San Francisco, you know that the Golden Gate Bridge is red.
And it's red because of the zinc paint that goes on those stainless steel cables.
That, if they start at one end of the bridge and they work to the other end, by the time they finish, it's already time to go back and start painting the beginning of the bridge again, because the bridge was built with steel cables, and steel cables can't take the salt air unless they're treated repeatedly with a zinc-based paint.
On the other hand, plant products like Manila hemp, you can drag through the ocean for weeks on end.
If you wanna tie your anchor to it and drop it right into the ocean, that's no problem, because plant fibers can stand up for months, even years, in direct contact with salt water.
OK. So how do you take plant fibers that individually you could break with your hands and turn them into a rope that's strong enough to moor a ship that weighs thousands of tons?
Well, what you do is you extract these long fibers from the Manila hemp plant, and then you take several of these fibers, and you group them into a bundle, because by grouping the fibers you greatly increase their breaking strength - that bundle of fibers is much stronger than any of the individual fibers that compose it.
And then you take that bundle of fibers and you twist it a little bit, because by twisting it, you increase its breaking strength even more.
And then you take several of these little bundles, and you group and twist them into bigger bundles, which you then group and twist into even bigger bundles, and so on, until eventually, you end up with a very, very strong rope. "
L2C2
"Listen to a conversation between two students. They are both studying to be English teachers.Did you register already for your classes next semester?
Yes, I did.
What are you taking?
Um... contemporary literature, English style, um... the teaching seminar, and I still have to do my student teaching.
I'm gonna help teach a writing class of the junior high.
That's a heavy schedule.
Yeah, it will be really busy and I'm also taking a theory class.
But I have to quit my job in a couple of weeks ,cause it will be just too much.
Where do you work at?
Buster's coffee shop, but just till the end of the month.
What are you doing next semester?
Actually a teaching seminar too.
And I will have to start writing my thesis.
You know, I'm also going for my master's degree.
So you are not writing any poetry, I imagine.
No, I was actually thinking about revising some of my poems and sending them into places for publication.
Cool, you should.
Um, did you hear about that new poetry club, The Poetry Kitchen?
Yeah, no time.
It's fun. It's Sunday night.
You don't do anything at Sunday nights?
I do homework Sunday nights.
Well, it's only from 7 to 9.
Is it every Sunday?
Last Sunday of every month. I don't know about this month, cause it's probably a little too close to Thanksgiving, so they might move it up.
I don't know what they are gonna do, but it's a good time, it's fun, some really impressive readings.
Who? From our class?
Some people from our class are reading.
A lot of them go, sometimes even the professor.
Really? I don't know if I would wanna read in front of her.
You wouldn't have to read, you can just watch.
I just watched the first time, but it's a good environment to read them, I think anyway.
I probably have to write something new, so maybe during the summer, I just can't now.
Yeah, it wouldn't be the same just reading old stuff.
Are you gonna do summer school?
Definitely. Otherwise, I will be short 6 credits, I have no choice.
Yeah, me too.
This is the second summer I'll have to take classes.
I gotta go now, my Shakespeare class starts in twenty minutes. "
L2L3
"Listen to part of a lecture in a philosophy class.OK. Another ancient Greek philosopher we need to discuss is Aristotle - Aristotle's ethical theory.
What Aristotle's ethical theory is all about is this: he's trying to show you how to be happy - what true happiness is.
Now, why is he interested in human happiness?
It's not just because it's something that all people want or aim for.
It's more than that.
But to get there we need to first make a very important distinction.
Let me introduce a couple of technical terms: extrinsic value and intrinsic value.
To understand Aristotle's interest in happiness, you need to understand this distinction.
Some things we aim for and value, not for themselves but for what they bring about in addition to themselves.
If I value something as a means to something else, then it has what we will call ""extrinsic value"".
Other things we desire and hold to be valuable for themselves alone.
If we value something not as a means to something else, but for its own sake, let us say that it has ""intrinsic value"".
Exercise. There may be some people who value exercise for itself, but I don't, I value exercise because if I exercise, I tend to stay healthier than I would if I didn't.
So I desire to engage in exercise and I value exercise extrinsically... not for its own sake, but as a means to something beyond it.
It brings me good health.
Health. Why do I value good health?
Well, here it gets a little more complicated for me.
Um, health is important for me because I can't... do other things I want to do - play music, teach philosophy - if I'm ill.
So health is important to me - has value to me - as a means to a productive life.
But health is also important to me because I just kind of like to be healthy - it feels good.
It's pleasant to be healthy, unpleasant not to be.
So to some degree I value health both for itself and as a means to something else: productivity.
It's got extrinsic and intrinsic value for me.
Then there's some things that are just valued for themselves.
I'm a musician, not a professional musician; I just play a musical instrument for fun.
Why do I value playing music?
Well, like most amateur musicians, I only play because, well, I just enjoy it.
It's something that's an end in itself.
Now, something else I value is teaching.
Why? Well, it brings in a modest income, but I could make more money doing other things.
I'd do it even if they didn't pay me.
I just enjoy teaching.
In that sense it's an end to itself.
But teaching's not something that has intrinsic value for all people - and that's true generally.
Most things that are enjoyed in and of themselves vary from person to person.
Some people value teaching intrinsically, but others don't.
So how does all this relate to human happiness?
Well, Aristotle asks: is there something that all human beings value... and value only intrinsically, for its own sake and only for its own sake?
If you could find such a thing, that would be the universal final good, or truly the ultimate purpose or goal for all human beings.
Aristotle thought the answer was yes.
What is it? Happiness.
Everyone will agree, he argues, that happiness is the ultimate end to be valued for itself and really only for itself.
For what other purpose is there in being happy?
What does it yield?
The attainment of happiness becomes the ultimate or highest good for Aristotle.
The next question that Aristotle raises is: what is happiness?
We all want it; we all desire it; we all seek it.
It's the goal we have in life.
But what is it? How do we find it?
Here he notes, with some frustration, people disagree.
But he does give us a couple of criteria, or features, to keep in mind as we look for what true human happiness is.
True human happiness should be, as he puts it, complete.
Complete in that it's all we require.
Well, true human happiness... if you had that, what else do you need?
Nothing.
And, second, true happiness should be something that I can obtain on my own.
I shouldn't have to rely on other people for it.
Many people value fame and seek fame.
Fame for them becomes the goal.
But, according to Aristotle, this won't work either, because fame depends altogether too much on other people.
I can't get it on my own, without help from other people.
In the end, Aristotle says that true happiness is the exercise of reason - life of intellectual contemplation... of thinking.
So let's see how he comes to that. "
L2L4
"Listen to part of a lecture in an astronomy class.You will not need to remember the numbers the professor mentions.
OK. Let's get going.
Today I'm going to talk about how the asteroid belt was discovered.
And... I'm going to start by writing some numbers on the board.
Here they are; We'll start with zero, then 3, ... 6, ... 12.
Uh, tell me what I'm doing.
Multiplying by 2?
Right, I'm doubling the numbers, so 2 times 12 is 24, and the next one I'm going to write after 24 would be...
48.
48. Then 96.
We'll stop there for now.
Uh, now I'll write another row of numbers under that.
Tell me what I'm doing.
4, 7, 10... How am I getting the second row?
Adding 4 to the numbers in the first row.
I'm adding 4 to each number in the first row to give you a second row.
So the last two will be 52, 100, and now tell me what I'm doing.
Putting in a decimal?
Yes, I divided all those numbers by 10 by putting in a decimal point.
Now I'm going to write the names of the planets under the numbers.
Mercury... Venus... Earth... Mars.
So, what do the numbers mean?
Do you remember from the reading?
Is it the distance of the planets from the Sun?
Right. In astronomical units - not perfect, but tantalizingly close.
The value for Mars is off by... 6 or 7 percent or so.
It's... but it's within 10 percent of the average distance to Mars from the Sun.
But I kind of have to skip the one after Mars for now.
Then Jupiter's right there at 5-point something, and then Saturn is about 10 astronomical units from the Sun.
Um, well, this pattern is known as Bode's Law.
Um, it isn't really a scientific law, not in the sense of predicting gravitation mathematically or something, but it's attempting a pattern in the spacing of the planets, and it was noticed by Bode hundreds of years ago.
Well, you can imagine that there was some interest in why the 2.8 spot in the pattern was skipped, and um... but there wasn't anything obvious there, in the early telescopes.
Then what happened in the late 1700s?
The discovery of...?
Another planet?
The next planet out, Uranus - after Saturn.
And look, Uranus fits in the next spot in the pattern pretty nicely, um, not perfectly, but close.
And so then people got really excited about the validity of this thing and finding the missing object between Mars and Jupiter.
And telescopes, remember, were getting better.
So people went to work on finding objects that would be at that missing distance from the Sun, and then in 1801, the object Ceres was discovered.
And Ceres was in the right place - the missing spot.
Uh, but it was way too faint to be a planet.
It looked like a little star.
Uh, and because of its star-like appearance, um, it was called an ""asteroid"".
OK? ""Aster"" is Greek for ""star"", as in ""astronomy"".
Um, and so, Ceres was the first and is the largest of what became many objects discovered at that same distance.
Not just one thing, but all the objects found at that distance form the asteroid belt.
So the asteroid belt is the most famous success of this Bode's Law.
That's how the asteroid belt was discovered. "
L3C1
"Listen to a conversation between a student and a receptionist at the Registrar's Office on the first day of the semester.Excuse me, I'm supposed to be having my physics class in the science building, but no one's in the classroom.
Could you tell me where the class is?
Physics 403 - has it been moved?
Well, there's a room assignment sheet on the bulletin board outside this office.
Yeah, I know, but my class isn't listed there.
There must be some kind of mistake or something.
Could you look it up, please?
Hmmm... ok, let me check on the computer.
It's physics, right?
Wait, did you say physics 403?
Yeah.
Er... I'm sorry, but it says here that it was cancelled.
You should have gotten a letter from the registrar's office about this.
What? I've never got it.
Are you sure?
Cause it says on the computer that the letter was sent out to students a week ago.
Really? I should have gotten it by now.
I wonder if I threw it away with all the junk mail by mistake.
Well, it does happen.
Er... let me check something. What's your name?
Woodhouse, Laura Woodhouse.
Ok, hmmm... Woodhouse, let me see... ah, it says here we sent it to your apartment on er... Center Street.
Oh, that's my old apartment.
I moved out of there a little while ago.
Well, and I suppose you haven't changed your mailing address at the administration office.
Well, that would explain it.
Yeah, I guess that's it.
But how can they cancel the class after offering it.
If I'd known this was gonna happen, I would have taken it last semester.
I know, it's really inconvenient for you, I understand that, but er... if we don't have enough students signed up for the course, the college can't offer it.
You know, it's a practical issue, like we can't have an instructor when there're only a few students in the class.
You see what I mean?
I guess, but now I don't know what course I should take instead.
Ok, let's see.
Do you have any courses you're gonna take next semester?
If you do, you might want to take them now and sign up for physics 403 next semester.
Yeah, I guess I could do that.
I just hope it won't be cancelled again.
Do you know how many people have to be enrolled in order to keep a class from being cancelled?
Well, it depends on the class, but for that class, you have to have er... let's see, usually it'd be at least ten people, but since it was cancelled this semester, they might even do it with less.
But do you know what you should do?
Give the physics department a call a couple of weeks before the semester starts.
They'll be able to tell you if they're planning to go through with it.
It's their decision, actually.
Oh, ok, I will do that.
Thanks for the info.
No problem.
Sorry about the class.
Oh, why don't you go change your mailing address now.
It'll only take a minute.
Oh, oh, sure, I will do that right away. "
L3L1
"Listen to part of a lecture in an environmental science class.Now, we've been talking about the loss of animal habitat from housing developments, um..., growing cities - small habitat losses.
But today I wanna begin talking about what happens when habitat is reduced across a large area.
There are, of course, animal species that require large areas of habitat, and some migrate over very long distances.
So what's the impact of habitat loss on those animals - animals that need large areas of habitat?
Well, I'll use the humming birds as an example.
Now you know a humming bird is amazingly small, but even though it's really tiny, it migrates over very long distances, travels up and down the western hemisphere - the Americas, back and forth between where it breeds in the summer and the warmer climates where it spends the winter.
So we would say that this whole area over which it migrates is its habitat because on this long-distance journey, it needs to come down to feed and sleep every so often, right?
Well, the humming bird beats its wings - get this - about 3 thousand times per minute.
So you think, wow, it must need a lot of energy, a lot of food, right?
Well, it does. It drinks a lot of nectar from flowers and feeds on some insects, but it's energy-efficient too.
You can't say it isn't.
I mean, as it flies all the way across the Gulf of Mexico, it uses up almost none of its body fat.
But that doesn't mean it doesn't need to eat.
So humming birds have to rely on plants in their natural habitat.
And it goes without saying, but, well, the opposite is true as well, plants depend on humming birds too.
There are some flowers that can only be pollinated by the humming birds.
Without its stopping to feed and spreading pollen from flower to flower, these plants would cease to exist.
But the problem, well, as natural habitat along these migration routes is developed by humans for housing or agriculture or cleared for raising cattle, for instance, there is less food available for migrating humming birds.
Their nesting sites are affected too, the same, by the same sorts of human activities.
And all of these activities pose a real threat to the humming bird population.
So to help them survive, we need to preserve their habitats.
And one of the concrete ways people have been doing this is by cleaning up polluted habitat areas and then replanting flowers, um, replanting native flowers that humming birds feed on.
Promoting ecological tourism is another way to help save their habitat.
As the number of visitors, eco-tourists who come to humming bird habitats to watch the birds, the more the number of visitors grows, the more local businesses profit, so ecological tourism can bring financial rewards, all the more reason to value these beautiful little creatures in their habitat, right?
But to understand more about how to protect and support humming birds the best we can, we've got to learn more about their breeding, nesting sites and migration routes, and also about the natural habitats we find there.
That should help us determine how to prevent further decline in the population.
A good research method, a good way to learn more, is by running a banding study.
Banding the birds allows us to track them over their lifetime.
It's a practice that's been used by researchers for years.
In fact, most of what we've known about humming birds comes from banding studies, where we capture a humming bird and make sure all the information about it, like its weight and age and length, are all recorded, put into international, an international information database.
And then we place an extremely lightweight band on one of its legs, well, what looks like a leg, although technically it's considered part of the bird's foot.
Anyway, these bands are perfectly safe, and some humming birds have worn them for years with no evidence of any problems.
The band is labeled with a tracking number, oh, and there is a phone number on the band for people to call for free, to report a banded bird they've found or recaptured.
So when a banded bird is recaptured and reported, we learn about its migration route, its growth, and how long it has been alive, its lifespan.
One recaptured bird had been banded almost 12 years earlier - she is one of the oldest humming birds on record.
Another interesting thing we've learned is that some humming birds, um, they no longer use a certain route.
They travel by a different route to reach their destination.
And findings like these have been of interest to biologists and environmental scientists in a number of countries who are trying to understand the complexities of how changes in a habitat affect the species in it, species like the humming birds. "
L3L2
"Listen to part of a lecture in a film history class.Okay, we've been discussing films in the 1920s and 30s, and how back then film categories, as we know them today, had not yet been established.
We said that by today's standards, many of the films of the 20s and 30s would be considered hybrids, that is, a mixture of styles that wouldn't exactly fit into any of today's categories.
And in that context, today we are going to talk about a film-maker who began making very unique films in the late 1920s.
He was French, and his name was Jean Painlevé.
Jean Painlevé was born in 1902.
He made his first film in 1928.
Now in a way, Painlevé's films conform to norms of the 20s and 30s, that is, they don't fit very neatly into the categories we use to classify films today.
That said, even by the standards of the 20s and 30s, Painlevé's films were a unique, hybrid of styles.
He had a special way of fusing, or some people might say, confusing, science and fiction.
His films begin with facts, but then they become more and more fictional.
They gradually add more and more fictional elements.
In fact, Painlevé was known for saying that science is fiction.
Painlevé was a pioneer in underwater film-making, and a lot of his short films focused on the aquatic animal world.
He liked to show small underwater creatures, displaying what seemed like familiar human characteristics - what we think of as unique to humans.
He might take a clip of a mollusk going up and down in the water and set it to music.
You know, to make it look as if the mollusk were dancing to the music like a human being - that sort of thing.
But then he suddenly changed the image or narration to remind us how different the animals are, how unlike humans.
He confused his audience in the way he portrayed the animals he filmed, mixing up our notions of the categories, human and animal.
The films make us a little uncomfortable at times because we are uncertain about what we are seeing.
It gives his films an uncanny feature: the familiar made unfamiliar, the normal made suspicious.
He liked twists, he liked the unusual.
In fact, one of his favorite sea animals was the sea-horse because with sea-horses, it's the male that carries the eggs, and he thought that was great.
His first and most celebrated underwater film is about the sea-horse.
Susan, you have a question?
But underwater film-making wasn't that unusual, was it?
I mean, weren't there other people making movies underwater?
Well, actually, it was pretty rare at that time.
I mean, we are talking the early 1930s here.
But what about Jacques Cousteau?
Wasn't he like an innovator, you know, with underwater photography too?
Ah, Jacques Cousteau.
Well, Painlevé and Cousteau did both film underwater, and they were both innovators, so you are right in that sense.
But that's pretty much where the similarities end.
First of all, Painlevé was about 20 years ahead of Cousteau.
And Cousteau's adventures were high-tech, with lots of fancy equipment, whereas Painlevé kind of patched equipment together as he needed it.
Cousteau usually filmed large animals, usually in the open sea, whereas Painlevé generally filmed smaller animals, and he liked to film in shallow water.
Uh, what else?
Oh well, the main difference was that Cousteau simply investigated and presented the facts - he didn't mix in fiction.
He was a strict documentarist.
He set the standard really for the nature documentary.
Painlevé, on the other hand, as we said before, mixed in elements of fiction.
And his films are much more artistic, incorporating music as an important element.
John, you have a question?
Well, maybe I shouldn't be asking this, but if Painlevé's films are so special, so good, why haven't we ever heard of them?
I mean, everyone's heard of Jacques Cousteau.
Well, that's a fair question.
Uh, the short answer is that Painlevé's style just never caught on with the general public.
I mean, it probably goes back at least in part to what we mentioned earlier, that people didn't know what to make of his films - they were confused by them, whereas Cousteau's documentaries were very straightforward, met people's expectations more than Painlevé's films did.
But your true, film history buffs know about him.
And Painlevé is still highly respected in many circles. "
L3C2
"Listen to a conversation between a student and a professor.Hi, Professor Archer, you know how in class last week you said that you were looking for students who were interested in volunteering for your archaeology project?
Of course, are you volunteering?
Yes, I am.
It sounds really interesting, but um... do I need to have any experience for these kinds of projects?
No, not really.
I assume that most students taking the introductory level class would have little or no experience with archaeological research, but that's ok.
Oh, good, that's a relief.
Actually, that's why I'm volunteering for the project - to get experience.
What kind of work is it?
Well, as you know, we're studying the history of the campus this semester.
This used to be an agricultural area and we already know that where the main lecture hall now stands, there once were farm house and barn that were erected in the late 1700s.
We were excavating near the lecture hall to see what types of artifacts we find, you know, things people used in the past that got buried when the campus was constructed.
We've already begun to find some very interesting items, like old bottles, buttons, pieces of clay pottery.
Buttons and clay pottery?
Did the old owners leave in such a hurry that they left their clothes and dishes behind?
Hmmm... that's just one of the questions we hope to answer with this project.
Wow, and it's all right here on campus.
That's right, no traveling involved.
I wouldn't expect volunteers to travel to a site, especially in the middle of the semester.
We expect to find many more things, but we do need more people to help.
So... how many student volunteers are you looking for?
I'm hoping to get five or six.
I've asked for volunteers in all of the classes I teach, but no one has responded.
You are the first person to express interest.
Sounds like it could be a lot of work.
Is there um... is there any way I can use the experience to get some extra credit in class?
I mean, can I write a paper about it?
I think it'll depend on what type of work you do in the excavation, but I imagine we can arrange something.
Actually I've been considering offering extra credit for class because I've been having a tough time getting volunteers.
Extra credit is always a good incentive for students.
And how often would you want the volunteers to work?
We're asking for three or four hours per week, depending on your schedule.
A senior researcher, I think you know John Franklin, my assistant, is on site every day.
Sure, I know John.
By the way, will there be some sort of training?
Yes, er... I want to wait till Friday to see how many students volunteer, and then I'll schedule a training class next week at a time that's convenient for everyone.
Ok. I'll wait to hear from you.
Thanks a lot for accepting me. "
L3L3
"Listen to part of a lecture in an Art History class.The professor has been discussing the origins of art.
Some of the world's oldest preserved art is the cave art of Europe, most of it in Spain and France.
And the earliest cave paintings found to date are those of the Chauvet Cave in France discovered in 1994.
And you know, I remember when I heard about the results of the dating of the Chauvet paintings, I said to my wife, ""Can you believe these paintings are over 30,000 years old?""
And my 3-year-old daughter piped up and said, ""Is that older than my great-grandmother?""
That was the oldest age she knew.
And you know, come to think of it.
It's pretty hard for me to really understand how long 30,000 years is too.
I mean, we tend to think that people who lived at that time must have been pretty primitive.
But I'm gonna show you some slides in a few minutes and I think you will agree with me that this art is anything but primitive.
They are masterpieces.
And they look so real, so alive that it's very hard to imagine that they are so very old.
Now, not everyone agrees on exactly how old.
A number of the Chauvet paintings have been dated by a lab to 30,000 or more years ago.
That would make them not just older than any other cave art, but about twice as old as the art in the caves at Altamira or Lascaux, which you may have heard of.
Some people find it hard to believe Chauvet is so much older than Altamira and Lascaux, and they noted that only one lab did the dating for Chauvet, without independent confirmation from any other lab.
But be that as it may, whatever the exact date, whether it's 15,000, 20,000 or 30,000 years ago, the Chauvet paintings are from the dawn of art.
So they are a good place to start our discussion of cave painting.
Now, one thing you've got to remember is the context of these paintings.
Paleolithic humans - that's the period we are talking about here, the Paleolithic, the early stone age, not too long after humans first arrived in Europe - the climate was significantly colder then, and so rock shelters, shallow caves were valued as homes protected from the wind and rain.
And in some cases at least, artists drew on the walls of their homes.
But many of the truly great cave art sites like Chauvet were never inhabited.
These paintings were made deep inside a dark cave, where no natural light can penetrate.
There's no evidence of people ever living here.
Cave bears, yes, but not humans.
You would have had to make a special trip into the cave to make the paintings, and a special trip to go see it.
And each time you'd have to bring along torches to light your way.
And people did go see the art.
There's charcoal marks from their torches on the cave walls clearly dating from thousands of years after the paintings were made.
So we can tell people went there.
They came but they didn't stay.
Deep inside a cave like that is not really a place you'd want to stay, so, why?
What inspired the Paleolithic artists to make such beautiful art in such inaccessible places?
We'll never really know, of course, though it's interesting to speculate.
But, um, getting to the paintings themselves, virtually all Paleolithic cave art represents animals, and Chauvet is no exception.
The artists were highly skilled at using, or even enhancing, the natural shape of the cave walls to give depth and perspectives to their drawings, the sense of motion and vitality in these animals.
Well, wait till I show you the slides.
Anyway, most Paleolithic cave art depicts large herbivores.
Horses are most common overall with deer and bison pretty common too, probably animals they hunted.
But earlier at Chauvet, there is a significant interest in large dangerous animals, lots of rhinoceros, lions, mammoth, bears.
Remember that the ranges of many animal species were different back then, so all these animals actually lived in the region at that time.
But the Chauvet artists didn't paint people.
There is a half-man-half-bison creature and there is outlines of human hands but no depiction of a full human.
So, why these precise animals?
Why not birds, fish, snakes?
Was it for their religion, magic or sheer beauty?
We don't know. But whatever it was, it was worth it to them to spend hours deep inside a cave with just a torch between them and utter darkness.
So, on that note, let's dim the lights, so we can see these slides and actually look at the techniques they used. "
L3L4
"Listen to part of a lecture in an astronomy class.Now astronomy didn't really bloom into the science it is today until the development of spectroscopy.
Spectroscopy is basically the study of spectra and spectral lines of light, and specifically for us, the light from stars.
It makes it possible to analyze the light emitted from stars.
When you analyze this light, you can figure out their distance from the earth, and identify what they are made of, determine their chemical composition.
Before we get into that, though, it's probably a good thing to back up a bit.
You all know how when you take a crystal prism and pass a beam of sunlight through it, you get a spectrum, which looks like a continuous band of rainbow colors.
The light that we see with our human eyes as a band of rainbow color falls in a range of what's called visible light.
And visible light spectroscopy is probably the most important kind of spectroscopy.
Anyone want to take a stab at the scientific term for visible light?
And I'm sure all of you know this because you all did the reading for today.
Optical radiation.
But I thought being exposed to radiation is dangerous.
Yes, and no.
If you are talking about radiation, like in the element Uranium, yeah, that's dangerous.
But radiation as a general term actually refers to anything that spreads away from its source.
So optical radiation is just visible light energy spreading out.
OK, so we've got a spectrum of a beam of sunlight and it looks like the colors bleed into each other.
There are no interruptions, just a band flowing from violet to green, to yellow, to... you get the idea.
Well, what happens if the sunlight's spectrum is magnified?
Maybe you all didn't do the reading.
Well, here's what you'd see.
I want you to notice that this spectrum is interrupted by dark lines called spectral lines.
If you really magnify the spectrum of the sunlight, you could identify more than 100,000 of them.
They may look like kind of randomly placed, but they actually form many distinct patterns.
And if you were looking at the spectrum of some other star, the colors would be the same.
But the spectral lines would break it up at different places, making different patterns.
Each pattern stands for a distinct chemical element, and so different sets or patterns of spectral lines mean that the star has a different chemical composition.
So how do we know which spectral patterns match up with which elements?
Well, a kind of spectroscopic library of elements was compiled using flame tests.
A known element, say a piece of iron for example, is heated in a pure gas flame.
The iron eventually heats to the point that it radiates light.
This light is passed through a prism, which breaks it up into a spectrum.
And a unique pattern, kind of like a chemical fingerprint of spectral lines for that element appears.
This process was repeated over and over again for many different elements, so we can figure out the chemical makeup of another star by comparing the spectral pattern it has to the pattern of the elements in the library.
Oh, an interesting story about how one of the elements was discovered through spectroscopy.
There was a pretty extensive library of spectral line patterns of elements even by the 1860s.
A British astronomer was analyzing a spectrograph of sunlight, and he noticed a particular pattern of spectral lines that didn't match anything in the library.
So he put two and two together, and decided there was an element in the sun that hadn't been discovered here on the earth yet.
Any guesses about what that element is?
It actually turned out to be pretty common and I'm sure all of you know it.
OK. Let's try something else.
Any of you happened to be familiar with the Greek word for ""sun"" by chance?
Something like ""Helius"" or something like that.
Oh it must be ""Helium"".
So you are saying that helium was discovered on the sun first.
Yes, and this is a good example of how important spectroscopy is in astronomy. "
L4C1
"Listen to a conversation between a student and a librarian.Can I help you?
Yeah, I need to find a review.
It's for my English class.
We have to find reviews of the play we are reading.
But they have to be from when the play was first performed, so I need to know when that was and I suppose I should start with newspaper reviews and…
Contemporary reviews.
Sorry?
You want contemporary reviews.
What's the name of the play?
It's Happy Strangers.
It was written in 1962 and we are supposed to write about its influence on American theatre and show why it's been so important.
Well, that certainly explains why your professor wants you to read some of those old reviews.
The critiques really tore the play to pieces when it opened.
It was just so controversial.
Nobody had ever seen anything like it on the stage.
Really? Is that a big deal?
Oh, sure. Of course the critics' reaction made some people kind of curious about it.
They wanted to see what was causing all the fuss.
In fact, we were on vacation in New York. Oh, I had to be, oh, around 16 years old, and my parents took me to see it.
That would've been about 1965.
So that was the year it premiered?
Great! But uh, newspapers from back then aren't online, so, how do I...
Well, we have copies of old newspapers in the basement, and all the major papers publish reference guides to their articles, reviews, etc.
You will find them in the reference stacks in the back.
But I start with 1964, I think the play had been running for a little while when I saw it.
How do you like it? I mean just two characters on the stage hanging around and basically doing nothing.
Well, I was impressed.
The actors were famous, and besides it was my first time in a real theatre.
But you are right.
It was definitely different from many plays that we read in high school.
Of course, in a small town the assignments are pretty traditional.
Yeah, I've only read it but it doesn't seem like it would be much fun to watch.
The story doesn't progress in any sort of logical manner, doesn't have a real ending neither, just stops.
Honestly, you know, I thought it was kind of slow and boring.
Oh, well I guess you might think that.
But when I saw it back then it was anything but boring.
Some parts were really funny, but I remember crying too.
But I'm not sure just reading it.
You know, they've done this play at least once on campus.
I'm sure there is a tape of the play in our video library.
You might want to borrow it.
That's a good idea.
I'll have a better idea of what I really think of it before I read those reviews.
I'm sure you will be surprised that anyone ever found it radical.
But you will see why it is still powerful, dramatically speaking.
Well, there must be something about it, or the professor wouldn't have assigned it.
I'm sure I'll figure it out. "
L4L1
"Listen to part of a lecture in a biology class.The class is discussing animal behavior.
Ok, the next kind of animal behavior I want to talk about might be familiar to you.
You may have seen, for example, a bird that's in the middle of a mating ritual, and suddenly it stops and preens, you know, takes a few moments to straighten its feathers, and then returns to the mating ritual.
This kind of behavior, this doing something that seems completely out of place, is what we call a ""Displacement Activity"".
Displacement activities are activities that animal's engaging in when they have conflicting drives.
If we take our example from a minute ago, if the bird is afraid of its mate, it's conflicted.
It wants to mate but it's also afraid and wants to run away.
So, instead, it starts grooming itself.
So, the displacement activity, the grooming, the straightening of its feathers, seems to be an irrelevant behavior.
So, what do you think another example of a displacement activity might be?
How about an animal that, um, instead of fighting its enemy or running away, it attacks a plant or a bush?
That's really good suggestion, Karl. But that's called ""redirecting"".
The animal is redirecting its behavior to another object, in this case, the plant or the bush.
But that's not an irrelevant or inappropriate behavior.
The behavior makes sense.
It's appropriate under the circumstances.
But what doesn't make sense is the object that the behavior is directed towards.
Ok, who else? Carol?
I think I read in another class about an experiment where an object that the animal was afraid of was put next to its food - next to the animal's food.
And the animal, it was conflicted between confronting the object and eating the food, so instead, it just fell asleep.
Like that?
That's exactly what I mean.
Displacement occurs because the animal's got two conflicting drives - two competing urges, in this case, fear and hunger.
And what happens is, they inhibit each other, they cancel each other out in a way, and a third seemingly irrelevant behavior surfaces through a process that we call ""Disinhibition"".
Now in disinhibition, the basic idea is that two drives that seem to inhibit, to hold back, a third drive.
Or, well, they're getting in a way of each other in a... in a conflict situation and somehow lose control, lose their inhibiting effect on that third behavior, which means that the third drive surfaces, it's expressed in the animal's behavior.
Now, these displacement activities can include feeding, drinking, grooming, even sleeping.
These are what we call ""Comfort Behavior"".
So why do you think displacement activities are so often comfort behaviors, such as grooming?
Maybe because it's easy for them to do?
I mean, grooming is like one of the most accessible things an animal can do.
It's something they do all the time, and they have the stimulus right there on the outside of their bodies in order to do the grooming, or if food is right in front of them.
Basically, they don't have to think very much about those behaviors.
Professor, isn't it possible that animals groom because they've got messed up a little from fighting or mating?
I mean if a bird's feathers get ruffled or an animal's fur, maybe it's not so strange for them to stop and tidy themselves up at that point.
That's another possible reason although it doesn't necessarily explain other behaviors such as eating, drinking or sleeping.
What's interesting is that studies have been done that suggest that the animal's environment may play a part in determining what kind of behavior it displays.
For example, there's a bird, the ""wood thrush"".
Anyway, when the ""wood thrush"" is in an attack-escape conflict, that is, it's caught between the two urges to escape from or to attack an enemy, if it's sitting on a horizontal branch, it'll wipe its beak on its perch.
If it's sitting on a vertical branch, it'll groom its breast feathers.
The immediate environment of the bird, its immediate, um, its relationship to its immediate environment seems to play a part in which behavior will display. "
L4L2
"Listen to part of a lecture in a literature class.All right, so let me close today's class with some thoughts to keep in mind while you are doing tonight's assignment.
You will be reading one of Ralph Waldo Emerson's best-known essays ""Self-Reliance"" and comparing it with his poems and other works.
I think this essay has the potential to be quite meaningful for all of you as young people who probably wonder about things like truth and where your lives are going - all sorts of profound questions.
Knowing something about Emerson's philosophies will help you when you read ""Self-Reliance"".
And basically, one of the main beliefs that he had was about truth.
Not that it's something that we can be taught, Emerson says it's found within ourselves.
So this truth, the idea that it's in each one of us, is one of the first points that you'll see Emerson making in this essay.
It's a bit abstract but he's very into... uh... into each person believing his or her own thought, believing in yourself, the thought or conviction that's true for you.
But actually, he ties that in with a sort of ""universal truth"" - something that everyone knows but doesn't realize they know.
Most of us aren't in touch with ourselves in a way, so we just aren't capable of recognizing profound truth.
It takes geniuses, people like, say, Shakespeare, who're unique because when they have a glimpse of this truth, this universal truth, they pay attention to it and express it and don't just dismiss it like most people do.
So Emerson is really into each individual believing in and trusting him or herself.
You'll see that he writes about, well, first, conformity.
He criticizes that people of his time for abandoning their own minds and their own wills for the sake of conformity and consistency.
They try to fit in with the rest of the world even though it's at odds with their beliefs and their identities.
Therefore, it's best to be a non-conformist - to do your own thing, not worrying about what other people think.
That's an important point.
He really drives this argument home throughout the essay.
When you are reading, I want you to think about that and why that kind of thought would be relevant to the readers of his time.
Remember this is 1838, ""Self-Reliance"" was a novel idea at the time and the United State's citizens were less secure about themselves as individuals and as Americans.
The country as a whole was trying to define itself.
Emerson wanted to give people something to really think about, help them find their own way and what it meant to be who they were.
So that's something that I think is definitely as relevant today as it was then, probably, um, especially among young adults like yourselves, you know, uh, college being a time to sort of really think about who you are and where you're going.
Now we already said that Emerson really emphasizes non-conformity, right, as a way to sort of not lose your own self and identity in the world, to have your own truth and not be afraid to listen to it.
Well, he takes this a step further.
Not conforming also means, uh, not conforming with yourself or your past.
What does that mean?
Well, if you've always been a certain way or done a certain thing, but it's not working for you any more, or you're not content, Emerson says that it'd be foolish to be consistent even with our own past.
""Focus on the future,"" he says, ""That's what matters more. Inconsistency is good.""
He talks about a ship's voyage and this is one of the most famous bits of the essay - how the best voyage is made up of zigzag lines.
Up close, it seems a little all over the place, but from farther away, the true path shows and in the end it justifies all the turns along the way.
So, don't worry if you are not sure where you're headed or what your long-term goals are.
Stay true to yourself and it'll make sense in the end.
I mean, I can attest to that.
Before I was a literature professor, I was an accountant.
Before that, I was a newspaper reporter.
My life is taking some pretty interesting turns and here I am, very happy with my experiences and where they've brought me.
If you rely on yourself and trust your own talents, your own interest, don't worry, your path will make sense in the end. "
L4C2
"Listen to a conversation between a student and a professor.Hey, Jane, you look like you are in a hurry.
Yeah, things are a little crazy.
Oh yeah? What's going on?
Oh, it's nothing.
Well, since it's your class, I guess it's OK.
It's, it's just I am having trouble with my group project.
Ah, yes, due next week.
What's your group doing again?
It's about the United States Supreme Court Decisions.
We are looking at the impact of recent cases on property rights, municipal land use cases, owning disputes.
Right, OK. And it's not going well?
Not really, I'm worried about the other two people in my group.
They are just sitting back, not really doing their fair share of the work and waiting for an A.
It's kind of stressing me out, because we are getting close to the deadline and I feel like I'm doing everything for this project.
Ah, the good old free rider problem.
Free rider?
Ah, it's just a term that describes this situation, when people in the group seek to get the benefits of being in a group without contributing to the work.
Anyway, what exactly do you mean when you say they just sit back?
I mean, they've been filing the weekly progress reports with me.
Yes, but I feel like I'm doing 90% of the work.
I hate to sound so negative here, but honestly, they are taking credit for things they shouldn't be taking credit for.
Like last week in the library, we decided to split up the research into 3 parts and then each of us was supposed to find sources in the library for our parts.
I went off to the stack and found some really good material for my part, but when I got back to our table, they were just goofing off and talking.
So I went and got materials for their sections as well.
Um... you know you shouldn't do that.
I know, but I didn't want to risk the project going down the drain.
I know Teresa and Kevin, I had both of them on other courses.
So, I'm familiar with the work and work habits.
I know, me too. That's why this has really surprised me.
Do you... does your group like your topic?
Well, I think we'd all rather focus on cases that deal with personal liberties, questions about freedom of speech, things like that.
But I chose property rights.
You chose the topic?
Yeah, I thought it would be good for us, all of us to try something new.
Um... maybe that's part of the problem.
Maybe Teresa and Kevin aren't that excited about the topic?
And since you picked it, have you thought... talk to them at all about picking a different topic?
But we've already got all the sources and it's due next week.
We don't have time to start from scratch.
OK, I will let you go cause I know you are so busy.
But you might consider talking to your group about your topic choice.
I will think about it.
Got to run, see you in class. "
L4L3
"Listen to part of a lecture in a geology class.Now we've got a few minutes before we leave for today.
So I'll just touch on an interesting subject that I think makes an important point.
We've been covering rocks and different types of rocks for the last several weeks.
But next week we are going to do something a bit different.
And to get started I thought I'd mention something that shows how uh... as a geologist, you need to know about more than just rocks and the structure of solid matter.
Moving rocks, you may have heard about them.
It's quite a mystery.
Death valley is this desert plain, a dry lake bed in California surrounded by mountains and on the desert floor these huge rocks, some of them hundreds of pounds.
And they move.
They leave long trails behind them, tracks you might say as they move from one point to another.
But nobody has been able to figure out how they are moving because no one has ever seen it happen.
Now there are a lot of theories, but all we know for sure is that people aren't moving the rocks.
There are no footprints, no tyre tracks and no heavy machinery like a bulldozer... uh, nothing was ever brought in to move these heavy rocks.
So what's going on?
Theory NO.1 - Wind?
Some researchers think powerful uh... windstorms might move the rocks.
Most of the rocks move in the same direction as the dominant wind pattern from southwest to northeast.
But some, and this is interesting, move straight west while some zigzag or even move in large circles.
Um... How can that be?
How about wind combined with rain?
The ground of this desert is made of clay.
It's a desert, so it's dry.
But when there is the occasional rain, the clay ground becomes extremely slippery.
It's hard for anyone to stand on, walk on.
Some scientists theorized that perhaps when the ground is slippery the high winds can then move the rocks.
There's a problem with this theory.
One team of scientists flooded an area of the desert with water, then try to establish how much wind force would be necessary to move the rocks.
And guess this, you need winds of at least five hundred miles an hour to move just the smallest rocks.
And winds that strong have never been recorded.
Ever! Not on this planet.
So I think it's safe to say that that issue has been settled.
Here is another possibility - ice.
It's possible that rain on the desert floor could turn to thin sheets of ice when temperatures drop at night.
So if rocks... uh becoming embedded in ice, uh... OK, could a piece of ice with rocks in it be pushed around by the wind?
But there's a problem with this theory, too.
Rocks trapped in ice together would have moved together when the ice moved.
But that doesn't always happen.
The rocks seem to take separate routes.
There are a few other theories.
Maybe the ground vibrates, or maybe the ground itself is shifting, tilting.
Maybe the rocks are moved by a magnetic force.
But sadly all these ideas have been eliminated as possibilities.
There's just no evidence.
I bet you are saying to yourself well, why don't scientists just set up video cameras to record what actually happens?
Thing is this is a protective wilderness area.
So by law that type of research isn't allowed.
Besides, in powerful windstorms, sensitive camera equipment would be destroyed.
So why can't researchers just live there for a while until they observe the rocks' moving?
Same reason.
So where are we now?
Well, right now we still don't have any answers.
So all this leads back to my main point - you need to know about more than just rocks as geologists.
The researchers studying moving rocks, well, they combine their knowledge of rocks with knowledge of wind, ice and such... not successfully, not yet.
But you know, they wouldn't even have been able to get started without uh, earth science understanding - knowledge about wind, storms, you know, meteorology.
You need to understand physics.
So for several weeks like I said we'll be addressing geology from a wider perspective.
I guess that's all for today.
See you next time. "
L4L4
"Listen to part of a lecture in a United States government class.OK, last time we were talking about government support for the arts.
Who can sum up some of the main points? Frank?
Well, I guess there wasn't really any, you know, official government support for the arts until the twentieth century.
But the first attempt the United States government made to, you know, to support the arts was the Federal Art Project.
Right, so what can you say about the project?
Um, it was started during the Depression, um... in the 1930s to employ out-of-work artists.
So was it successful? Janet, what do you say?
Yeah, sure, it was successful.
I mean, for one thing, the project established a lot of, uh like community art centers and galleries in places like rural areas where people hadn't really had access to the arts.
Right.
Yeah. But didn't the government end up wasting a lot of money for art that wasn't even very good?
Uh, some people might say that.
But wasn't the primary objective of the Federal Art Project to provide jobs?
That's true. I mean, it did provide jobs for thousands of unemployed artists.
Right. But then when the United States became involved in the Second World War, unemployment was down and it seems that these programs weren't really necessary any longer.
So, moving on, we don't actually see any govern... well any real government involvement in the arts again until the early 1960s, when President Kennedy and other politicians started to push for major funding to support and promote the arts.
It was felt by a number of politicians that... well that the government had a responsibility to support the arts as sort of... oh, what can we say... the the soul... or spirit of the country.
The idea was that there be a federal subsidy... um... uh... financial assistance to artists and artistic or cultural institutions.
And for just those reasons, in 1965, the National Endowment for the Arts was created.
So it was through the NEA, the National Endowment for the Arts, um, that the arts would develop, would be promoted throughout the nation.
And then individual states throughout the country started to establish their own state arts councils to help support the arts.
There was kind of uh... cultural explosion.
And by the mid 1970s, by 1974 I think, all fifty states had their own arts agencies, their own state arts councils that work with the federal government with corporations, artists, performers, you name it.
Did you just say corporations?
How were they involved?
Well, you see, corporations aren't always altruistic.
They might not support the arts unless... well, unless the government made it attractive for them to do so, by offering corporations tax incentives to support the arts, that is, by letting corporations pay less in taxes if they were patrons of the arts.
Um, the Kennedy Centre in Washington D.C. you may uh... maybe you've been there, or Lincoln Centre in New York.
Both of these were built with substantial financial support from corporations.
And the Kennedy and Lincoln center's aren't the only examples.
Many of your cultural establishments in the United States will have a plaque somewhere acknowledging the support - the money they received from whatever corporation.
Oh, yes, Janet?
But aren't there a lot of people who don't think it's the government's role to support the arts?
Well, as a matter of fact, a lot of politicians who did not believe in government support for the arts, they wanted to do away with the agency entirely, for that very reason, to get rid of governmental support.
But they only succeeded in taking away about half the annual budget.
And as far as the public goes, well, there are about as many individuals who disagree with the government support as there are those who agree.
In fact, with artists in particular, you have lots of artists who support and who have benefited from this agency, although it seems that just as many artists oppose a government agency being involved in the arts, for many different reasons, reasons like they don't want the government to control what they create.
In other words, the arguments both for and against government funding of the arts are as many and, and as varied as the individual styles of the artists who hold them. "
L5C1
"Listen to a conversation between a student and a counselor at the University Counseling Center.Hi, thanks for seeing me on such short notice.
No problem.
How can I help?
Well, I think I might have made a mistake coming to the school.
What makes you say that?
I'm a little overwhelmed by the size of this place.
I come from a small town.
There were only 75 of us in my high school graduating class.
Everyone knew everyone.
We all grew up together.
So it's a bit of a culture shock for you?
Being one of 15,000 students on a big campus in an unfamiliar city?
That's an understatement.
I just can't get comfortable in class or in the dorms.
You know, socially.
Um... well, let's start with the academics.
Tell me about your classes.
I'm taking mostly introductory courses and some are taught in these huge lecture halls.
And you are having trouble in keeping pace with the material?
No, in fact I got an A on my first economics paper.
It's just that, it's so impersonal, I'm not used to it.
Are all your classes impersonal?
No, it's just that, for example, in sociology yesterday, the professor asked a question, so I raised my hand, several of us raised our hands.
And I kept my hand up because I did the reading and knew the answer.
But the professor just answered his own question and continued with the lecture.
Well, in a big room it's possible he didn't notice you.
Maybe he was trying to save time.
In either case I wouldn't take it personally.
I suppose. But I just don't know how to, you know, distinguish myself.
Why not stop by his office during office hours?
That wouldn't seem right.
You know, taking time from other students who need help?
Don't say that. That's what office hours are for.
There is no reason you couldn't pop in to say hi and to make yourself known.
If you are learning a lot in class, let the professor know.
Wouldn't you appreciate positive feedback if you were a professor?
You are right. That's a good idea.
OK, er... let's turn to your social life.
How's it going in the dorms?
I don't have much in common with my roommate or anyone else I've met so far.
Everyone's into sports and I'm more artsy, you know, into music.
I play the cello.
Hah, have you been playing long?
Since age ten.
It's a big part of my life.
At home I was the youngest member of our community orchestra.
You are not going to believe this.
There is a string quartet on campus, all students.
And it so happened that the cellist graduated last year.
They've been searching high and low for a replacement, someone with experience.
Would you be interested in auditioning?
Absolutely.
I wanted to get my academic work settled before pursuing my music here.
But I think this would be a good thing for me.
I guess if I really want to fit in here I should find people who love music as much as I do.
Thank you.
My pleasure. "
L5L1
"Listen to part of a lecture in a sociology class.Have you ever heard the one about alligators living in New York sewers?
The story goes like this: a family went on vacation in Florida and bought a couple of baby alligators as presents for their children, then returned from vacation to New York, bringing the alligators home with them as pets.
But the alligators would escape and find their way into the New York sewer system where they started reproducing, grew to huge sizes and now strike fear into sewer workers.
Have you heard this story?
Well, it isn't true and it never happened.
But despite that, the story has been around since the 1930s.
Or how about the song ""twinkle, twinkle little star"", you know, ""twinkle, twinkle, little star, how I wonder what you are.""
Well we've all heard this song.
Where am I going with this?
Well, both the song and the story are examples of memes.
And that's what we would talk about, the theory of memes.
A meme is defined as a piece of information copied from person to person.
By this definition, most of what you know, ideas, skills, stories, songs are memes.
All the words you know, all the scientific theories you've learned, the rules your parents taught you to observe, all are memes that have been passed on from person to person.
So what? You may say.
Passing on ideas from one person to another is nothing new.
Well, the whole point of defining this familiar process as transmission of memes is so that we can explore its analogy with the transmission of genes.
As you know, all living organisms pass on biological information through the genes.
What's a gene?
A gene is a piece of biological information that gets copied or replicated, and the copy or replica is passed on to the new generation.
So genes are defined as replicators.
Genes are replicators that pass on information about properties and characteristics of organisms.
By analogy, memes also get replicated and in the process pass on culture information from person to person, generation to generation.
So memes are also replicators.
To be a successful replicator, there are three key characteristics: longevity, fecundity and fidelity.
Let's take a closer look.
First, longevity.
A replicator must exist long enough to be able to get copied, and transfer its information.
Clearly, the longer a replicator survives, the better its chances of getting its message copied and passed on.
So longevity is a key characteristic of a replicator.
If you take the alligator story, it can exist for a long time in individual memory, let's say, my memory.
I can tell you the story now or ten years from now, the same with the twinkle, twinkle song.
So these memes have longevity because they are memorable for one reason or another.
Next, fecundity.
Fecundity is the ability to reproduce in large numbers.
For example, the common housefly reproduces by laying several thousand eggs, so each fly gene gets copied thousands of times.
Memes, well, they can be reproduced in large numbers as well.
How many times have you sung the ""twinkle, twinkle song"" to someone?
Each time you replicated that song, and maybe passed it along to someone who did not know it yet, a small child maybe.
And finally, fidelity.
Fidelity means accuracy of the copying process.
We know fidelity is an essential principle of genetic transmission.
If a copy of a gene is a bit different from the original, that's called a genetic mutation.
And mutations are usually bad news.
An organism often cannot survive with a mutated gene.
And so a gene usually cannot be passed on, unless it's an exact copy.
For memes however, fidelity is not always so important.
For example, if you tell someone the alligator story I told you today, it probably won't be word for word exactly as I said it.
Still, it will be basically the same story, and the person who hears the story will be able to pass it along.
Other memes are replicated with higher fidelity though, like the twinkle, twinkle song.
It had the exact same words 20 years ago as it does now.
Well, that's because we see songs as something that has to be performed accurately each time.
If you change a word, the others will usually bring you in line.
They'll say, ""that's not how you sing it"", right?
So, you can see how looking at pieces of cultural information as replicators, as memes, and analyzing them in terms of longevity, fecundity and fidelity, we can gain some inside about how they spread, persist or change. "
L5L2
"Listen to part of a lecture in an Astronomy Class.Last week, we covered some arguments against going back to the Moon.
But there are compelling reasons in favor of another Moon landing too, um... not the least of which is trying to pinpoint the moon's age.
We could do this in theory by studying an enormous impact crater, known as the South Pole-Aitken Basin.
Um... it's located in the moon's South Polar Region.
But, since it's on the far side of the moon, it can only be seen from space.
Here is an image of, we'll call it the SPA Basin.
This color-coated image of the SPA Basin, those aren't its actual colors obviously, this image is from the mid 90s, from the American spacecraft called Clementine.
Um... unlike earlier lunar missions, Clementine didn't orbit only around the moon's equator.
Its orbits enable it to send back data to create this topographical map of, well, the grey and white area towards the bottom is the South Pole, the purples and blues in the middle correspond to low elevations - the SPA Basin itself, the oranges and reds around it are higher elevations.
The basin measures an amazing 2,500 km in diameter, and its average depth is 12 km.
That makes it the biggest known crater in our solar system and it may well be the oldest.
You know planetary researchers love studying deep craters until learn about the impacts that created them, how they redistributed pieces of a planet's crust and in this case, we especially want to know if any of the mantle, the layer beneath the crust, was exposed by the impact.
Not everyone agrees, but some experts are convinced that whatever created the SPA Basin did penetrate the Moon's mantle.
And we need to find out, because much more than the crust, the mantle contains information about a planet's or Moon's total composition.
And that's key to understanding planet formation.
Um... Dian?
So, the only way to know the basin's age is to study its rocks directly?
Well, from radio survey data, we know that the basin contains lots of smaller craters.
So it must be really old, about 4 billion years, give or take a few hundred million years.
But that's not very precise.
If we had rock samples to study, we'd know whether the small craters were formed by impacts during the final stages of planetary formation, or if they resulted from later meteor showers.
But if we know around how old the Basin is, I'm not sure that's reason enough to go to the Moon again.
No... but such crude estimates, um... we can do better than that.
Besides, there are other things worth investigating, like is there water ice on the moon?
Clementine's data indicated that the wall of the south-polar crater was more reflective than expected.
So some experts think there's probably ice there.
Also, data from a later mission indicates significant concentrations of hydrogen and by inference water less than a meter underground at both poles.
Well if there's water, how did it get there? Underground rivers?
We think meteors that crashed into the moon or tails of passing comets may have introduced water molecules.
Any water molecules that found their way to the floors of craters near the moon's poles, that water would be perpetually frozen, because the floors of those craters are always in shadow.
Um... furthermore, if the water ice was mixed in with rock and dust, it would be protected from evaporation.
So are you saying there might be primitive life on the moon?
That's not my point at all.
Um... OK, say there is water ice on the moon.
That would be a very practical value for a future moon base for astronauts.
Water ice could be melted and purified for drinking.
It could also be broken down into its component parts - oxygen and hydrogen.
Oxygen could be used to breathe, and hydrogen could be turned into fuel, rocket fuel.
So water ice could enable the creation of a self-sustaining moon base someday, a mining camp perhaps or a departure point for further space exploration.
But holding tons of equipment to the moon to make fuel and build a life support system for a moon base, wouldn't that be too expensive?
Permanent base, maybe a ways off, but we shouldn't have to wait for that.
The dust at the bottom of the SPA Basin really does have a fascinating story to tell.
I wouldn't give for a few samples of it. "
L5C2
"Listen to a conversation between a student and a professor.Hi, I was wondering if I could talk with you about the assignment in the film theory class.
Of course, Jill.
It seems that pretty much everyone else in the class gets what they are supposed to be doing but I'm not so sure.
Well, the class is for students who are really serious about film.
You must have taken film courses before.
Yeah, in high school, film appreciation.
Um... I wouldn't think that would be enough.
Did you concentrate mainly on form or content?
Oh, definitely content.
We'd watch, say Lord of the Flies, and then discuss it.
Oh, that approach, treating film as literature, ignoring what makes it unique.
I liked it, though.
Sure, but that kind of class.
Well, I'm not surprised that you are feeling a little lost.
You know, we have two introductory courses that are supposed to be taken before you get to my course, one in film art, techniques, technical stuff and another in film history.
So students in the class you are in should be pretty far along in film studies.
In fact, usually the system blocks anyone trying to sign up for a class they shouldn't be taking.
Those who hasn't taken the courses as you are required to do first as prerequisites.
Well, I did have a problem with that but I discussed it with one of your office staff, and she gave me permission.
Of course. No matter how many times I tell them, they just keep on.
Well, for your own good, I'd really suggest dropping back and starting at the usual place.
Yes. But I've already been in this class for 4 weeks.
I'd hate to just drop it now especially since I find it so different, so interesting.
I guess so. Frankly I can't believe you've lasted this long.
These are pretty in-depth theories we've been discussing and you've been doing OK so far, I guess.
But still, the program's been designed to progress through certain stages.
Like any other professional training we build on previous knowledge.
Then maybe you could recommend some extra reading I can do to catch up?
Well, are you intending to study film as your main concentration?
No, no, I am just interested.
I'm actually in marketing, but there seems to be a connection.
Oh... well, in... in that case, if you're taking the course just out of interest, I mean I still highly recommend signing up for the introductory courses at some point, but in the meantime, there is no harm I guess in trying to keep up with this class.
The interest is clearly there.
Eh... instead of any extra reading just now though, you could view some of the old introductory lectures.
We have them on video.
That would give you a better handle on the subject.
It's still a pretty tall order, and we will be moving right along, so you will really need to stay on top of it.
OK, I've been warned.
Now, could I tell you about my idea for the assignment? "
L5L3
"Listen to part of a lecture in a chemistry class.Okay, I know you all have a lot of questions about this lab assignment that's coming out so, I'm gonna take a little time this morning to discuss it.
So, you know the assignment has to do with Spectroscopy, right?
And your reading should help you get a good idea of what that's all about.
But, let's talk about Spectroscopy a little now just to cover the basics.
What is Spectroscopy?
Well, the simplest definition I can give you is that Spectroscopy is the study of the interaction between matter and light.
Now, visible light consists of different colors or wavelengths, which together make up what's called spectrum, a band of colors, like you see in a rainbow.
And all substances, all forms of matter, can be distinguished according to what wavelength of light they absorb and which ones they reflect.
It's like, um, well, every element has, what we call, its own spectral signature.
If we can read that signature, we can identify the element.
And that's exactly what spectroscopy does.
Now, Laser Spectroscopy, which is the focus of your assignment, works by measuring very precisely what parts of the spectrum are absorbed by different substances.
And it has applications in a lot of different disciplines.
And your assignment will be to choose a discipline that interests you, and devise an experiment.
For example, I'm gonna talk about art. I'm interested in the art and to me it's interesting how spectroscopy is used to analyze art.
Er... let's say a museum curator comes to you with a problem.
She's come across this painting that appears to be an original - let's say, a Rembrandt.
And she wants to acquire it for her museum.
But she's got a problem: she's not absolutely certain it's an original.
So, what do you do? How do you determine whether the painting's authentic?
Okay. Think about the scientific process.
You've got the question: Is the painting a Rembrandt?
So first, you'll need to make a list of characteristics the painting would have to have to be a Rembrandt.
Then you have to discover whether the painting in question has those characteristics.
So first of all, you'll need to know the techniques Rembrandt used when he applied paint to canvas - his brushstrokes, how thickly he applied his paint.
So you'd need to work with an art historian who has expert knowledge of Rembrandt's style.
You'd have to know when he created his paintings, um, what pigments he used, in other words, what ingredients he used to make different colors of paint, coz the ingredients used in paints and binding agents plus varnishes, finishes, what have you, have changed over time.
Since you're trying to verify that's a Rembrandt, the ingredients in the pigment would need to have been used during Rembrandt's lifetime - in the 17th century.
And that's where chemistry comes in.
You've got to find out what's in those pigments, learn their composition, and that requires lab work - detective work really - in a word, Spectroscopy.
So, how do we use Spectroscopy?
Well, we put an infrared microscope - a spectroscope - on tiny tiny bits of paint.
And using ultraviolet light we can see the spectral signature of each component part of the pigment.
Then we compare these signatures with those of particular elements like zinc or lead, to determine what the pigment was made of.
So, you can see why this type of analysis requires a knowledge of the history of pigments, right?
How and when they were made?
Say we determined a pigment was made with zinc, for example.
We know the spectral signature of zinc.
And it matches that of the paint sample.
We also know that zinc wasn't discovered until the 18th century.
And since Rembrandt lived during the 17th century, we know he couldn't have painted it.
Now, Spectroscopy has a very distinct advantage over previous methods of analyzing art works, because it's not invasive.
You don't have to remove big chips of paint to do your analysis, which is what other methods require.
All you do is train the microscope on tiny flecks of paint and analyze them.
Now a word or two about restoration.
Sometimes original art works appear questionable or inauthentic because they've had so many restorers add touch-up layers to cover up damage, damage from the paint having deteriorated over time.
Well, spectroscopy can review the composition of those touch-up layers too.
So we can find out when they were applied.
Then if we want to undo some bad restoration attempts, we can determine what kind of process we can use to remove them to dissolve the paint and uncover the original. "
L5L4
"Listen to part of a lecture in a literature class.Now we can't really talk about fairy tales without first talking about folk tales because there's a strong connection between these two genres, these two types of stories.
In fact, many fairy tales started out as folk tales.
So, what's a folk tale? How would you characterize them? Jeff?
Well, they are old stories, traditional stories.
They were passed down orally within cultures from generation to generation, so they changed a lot over time.
I mean, every story teller, or, maybe every town, might have had a slightly different version of the same folk tale.
That's right. There's local difference.
And that's why we say folk tales are communal.
By communal, we mean they reflect the traits and the concerns of a particular community at a particular time.
So essentially the same tale could be told in different communities, with certain aspects of the tale adapted to fit the specific community.
Um, not the plot, the details of what happens in the story would remain constant.
That was the thread that held the tale together.
But all the other elements, like the location or characters, might be modified for each audience.
Okay. So what about fairy tales?
They also are found in most cultures, but how are they different from folk tales?
I guess the first question is: what is a fairy tale?
And don\'t anyone say \""a story with a fairy in it\"" because we all know that very few fairy tales actually have those tiny magical creatures in them.
But, what else can we say about them? Mary.
Well, they seem to be less realistic than folk tales, like they have something improbable happening - a frog turning into a prince, say.
Oh, that's another common element, royalty - a prince or princess.
And fairy tales all seem to take place in a location that's nowhere and everywhere at the same time.
What's the line-up? How do all those stories start?
Once upon a time, in a faraway land, oh, in the case of folk tales, each story teller would specify a particular location and time, though the time and location would differ for different story tellers.
With fairy tales, however, the location is generally unspecified, no matter who the story teller is.
That land far away, We'll come back to this point in a few minutes.
Um... I, I thought that a fairy tale was just a written version of an oral folk tale.
Well, not exactly, though that is how many fairy tales developed.
For example, in the late 18th century, the Grimm Brothers traveled throughout what's now Germany, recording local folk tales.
These were eventually published as fairy tales, but not before undergoing a process of evolution.
Now, a number of things happen when an oral tale gets written down.
First, the language changes. It becomes more formal, more standard - some might say, ""Less colorful"".
It's like the difference in your language depending on whether you are talking to someone, or writing them a letter.
Second, when an orally transmitted story is written down, an authoritative version with a recognized author is created.
The communal aspect gets lost.
The tale no longer belongs to the community.
It belongs to the world, so to speak.
Because of this, elements like place and time can no longer be tailored to suit a particular audience.
So they become less identifiable, more generalizable to any audience.
On the other hand, descriptions of characters and settings can be developed more completely.
In folk tales, characters might be identified by a name, but you wouldn't know anything more about them.
But in fairy tales, people no longer have to remember plots.
They're written down, right?
So more energy can be put into other elements of the story like character and setting.
So you get more details about the characters, about where the action takes place, what people's houses were like, um, whether they're small cabins or grand palaces.
And it's worth investing that energy because the story, now in book form, isn't in danger of being lost.
Those details won't be forgotten.
If a folk tale isn't repeated by each generation, it may be lost for all time.
But with a fairy tale, it's always there in a book, waiting to be discovered, again and again.
Another interesting difference involves the change in audience.
Who the stories are meant for?
Contrary to what many people believe today, folk tales were originally intended for adults, not for children.
So why is it that fairy tales seem targeted toward children nowadays? "
L6C1
"Listen to a conversation between a student and an employee in the university's career services office.Hi, do you have a minute?
Sure, how can I help you?
I have a couple of questions about the career fair next week.
OK, shoot.
Um, well, are seniors the only ones who can go?
I mean, you know, they are finishing school this year and getting their degrees and everything.
And, well, it seems like businesses would wanna talk to them and not first year students like me.
No, no, the career fair is opened to all our students and we encourage anyone who's interested to go check it out.
Well, that's good to know.
You've seen the flyers and posters around campus, I assume.
Sure, can't miss them. I mean, they all say where and when the fair is, just not who should attend.
Actually they do, but it's in the small print.
Uh, we should probably make that part easier to reach, shouldn't we?
I'll make a note of that right now.
So, do you have any other questions?
Yes, actually I do now.
Um, since I'd only be going to familiarize myself with the process, you know, check it out, I was wondering if there is anything you could recommend that I do to prepare.
That's actually a very good question.
Well, as you know, the career fair is generally an opportunity for local businesses to recruit new employees, and for soon-to-be graduates to have interviews with several companies they might be interested in working for.
Now, in your case, even though you wouldn't be looking for employment right now, it still wouldn't hurt for you to prepare much like you would if you were looking for a job.
You mean, like get my resume together and wear a suit?
That's a given.
I was thinking more along the lines of doing some research.
The flyers and posters list all the businesses that are sending representatives to the career fair.
Um, what's your major urge you to have one yet?
Well, I haven't declared a major yet, but I'm strongly considering accounting.
See, that's part of the reason I wanna go to the fair, to help me decide if that's what I really want to study.
That's very wise.
Well, I suggest that you get on the computer and learn more about the accounting companies in particular that would be attending.
You can learn a lot about companies from their internet websites.
Then prepare a list of questions.
Questions, hmm... so, in a way, I'll be interviewing them?
That's one way of looking at it.
Think about it for a second. What do you want to know about working for an accounting firm?
Well, there is the job itself, and salary of course, and working conditions, I mean, would I have an office, or would I work in a big room with a zillion other employees, and, and maybe about opportunities for advancement.
See? Those're all important things to know.
After you do some research, you'll be able to tailor your questions to the particular company you are talking to.
Wow, I'm glad I came by here.
So, it looks like I've got some work to do.
And if you plan on attending future career fairs, I recommend you sign up for one of our interview workshops.
I'll do that. "
L6L1
"Listen to part of a lecture in an economics class.Now when I mention the terms ""boom and bust"",what does that bring to mind?
The dot com crash of the 90s.
OK. The boom in the late 1990s when all those new Internet companies sprung up and were then sold for huge amounts of money.
Then the bust around 2000, 2001 when many of those same Internet companies went out of business.
Of course, booms aren't always followed by busts.
We've certainly seen times when local economies expanded rapidly for a while and then went back to a normal pace of growth.
But, there's a type of rapid expansion, what might be called the hysterical or irrational boom that pretty much always leads to a bust.
See, people often create and intensify a boom when they get carried away by some new industry that seems like it will make lots of money fast.
If you think that by the 90s, people would have learned from the past.
If they did, well, look at tulips.
Tulips? You mean like the flower?
Exactly. For instance, do you have any idea where tulips are from? Originally I mean.
Well, the Netherlands, right?
That's what most people think, but no.
They are not native to the Netherlands, or even Europe.
Tulips actually hail from an area that Chinese call the Celestial Mountains in Central Asia.
A very remote mountainous region.
It was Turkish nomads who first discovered tulips and spread them slowly westward.
Now, around the 16th century, Europeans were traveling to Istanbul and Turkey as merchants and diplomats.
And the Turks often gave the Europeans tulip bulbs as gifts which they would carry home with them.
For the Europeans, tulips were totally unheard of, er, a great novelty.
The first bulb to show up in the Netherlands, the merchant who received them roasted and ate them.
He thought they were kind of onion.
It turns out that the Netherlands was an ideal country for growing tulips.
It had the right kind of sandy soil for one thing, but also, it was a wealthy nation with a growing economy, willing to spend lots of money on new exotic things.
Plus, the Dutch had a history of gardening.
Wealthy people would compete, spending enormous amounts of money to buy the rarest flowers for their gardens.
Soon tulips were beginning to show up in different colors as growers tried to breed them specifically for colors which would make them even more valuable.
But they were never completely sure what they would get.
Some of the most priced tulips were white with purple streaks, or red with yellow streaks on the petals, even a dark purple tulip that was very much priced.
What happened then was a craze for these specialized tulips.
We called that craze ""tulip mania"".
So, here we've got all the conditions for an irrational boom: a prospering economy, so more people had more disposable income - money to spend on luxuries, but they weren't experienced at investing their new wealth.
Then along comes a thrilling new commodity.
Sure the first specimens were just plain old red tulips, but they could be bred into some extraordinary variations, like that dark purple tulip.
And finally, you had an unregulated market place, no government constrains, where prices could explode.
And explode they did, starting in the 1630s.
There was always much more demand for tulips than supply.
Tulips didn't bloom frequently like roses. Tulips bloomed once in the early spring.
And that was it for the year.
Eventually, specially-bred multicolored tulips became so valuable, well, according to records, one tulip bulb was worth 24 tons of wheat, or thousand pounds of cheese.
One particular tulip bulb was sold and exchanged for a small ship.
In other words, tulips were literally worth their weight in gold.
As demand grew, people began selling promissory notes guaranteeing the future delivery of priced tulip bulbs.
The buyers of these pieces of paper would resell the notes at marked up prices.
These promissory notes kept changing hands from buyer to buyer until the tulip was ready for delivery.
But it was all pure speculation because as I said, there was no way to know if the bulb was really going to produce the variety, the color that was promised.
But that didn't matter to the owner of the note.
The owner only cared about having that piece of paper so it could be traded later at a profit.
And people were borrowing, mortgaging their homes in many cases to obtain those bits of paper because they were sure they'd find an easy way to make money.
So now, you've got all the ingredients for a huge bust.
And bust it did, when one cold February morning in 1637, a group of bulb traders got together and discovered that suddenly there were no bidders.
Nobody wanted to buy.
Panic spread like wild fire and the tulip market collapsed totally. "
L6L2
"Listen to part of a lecture in a biology class.Ok, I have an interesting plant species to discuss with you today.
Um... it's a species of a very rare tree that grows in Australia, Eidothea hardeniana.
But it's better known as the Nightcap Oak.
Now, it was discovered only very recently, just a few years ago.
Um... it remained hidden for so long because it's so rare.
There are only about 200 of them in existence.
They grow in a rain forest, in a mountain ridge, range in the north part of New South Wales which is er... a state in Australia.
So just 200 individual trees in all.
Now another interesting thing about the Nightcap Oak is that it is, it represents, er... a very old type, er... kind of tree that grew a hundred million years ago.
Um... we found fossils that old the bear remarkable resemblance to the tree.
So, it's a primitive tree.
A... a living fossil you might say.
It's relic from earlier times and it has survived all these years without much change.
And it, it's probably a kind of tree from which other trees that grow in Australia today evolved.
Just to give you an idea of what we are talking about.
Here's a picture of the leaves of the tree and its flowers.
I don't know how well you can see the flowers.
They're those little clusters sitting at the base of the leaves.
Okay, what have we tried to find out about the tree since we've discovered it?
Hum... or how, why is, is it so rare? That's one of the first questions.
Um... how is it, um... how does it reproduce? This's another question.
Um... maybe those two questions are actually related. Jim?
Hum... I don't know.
But I can imagine that, for instance, seed dispersal might be a factor.
I mean if the, er... you know, if the seeds cannot really disperse in the wild area, then, you know, the tree may not colonize new areas.
It can't spread from the area where it's growing.
Right. That's, that's actually a very good answer.
Um... of course, you might think there might not be many areas where the tree could spread into, er... because, um... well, it's very specialized in terms of the habitat.
But, that's not really the case here.
Um... the suitable habitat, that is, the actual rainforest is much larger than the few hectares where the Nightcap Oak grows.
Now this tree is a flowering tree as I showed you.
Um... um... it produces a fruit, much like a plum.
On the inci... inside there's a seed with a hard shell.
It, it appears that the shell has to crack open or break down somewhat to allow the seed to soak up water.
If the Nightcap Oak remains, if their seeds remain locked inside their shell, they will not germinate.
Actually, the seeds, er... they don't retain the power to germinate for very long, maybe two years.
So there's actually quite a short window of opportunity for the seed to germinate.
So the shell somehow has to be broken down before this, um... germination ability expires.
And, and then there's a kind of rat that likes to feed on the seeds as well.
So, given all these limitations, not many seeds that the tree produces will actually germinate.
So this is a possible explanation for why the tree does not spread.
It doesn't necessarily explain how it became so rare, but it explains why it doesn't increase.
OK, so it seems to be the case that the species, this Nightcap Oak is not very good at spreading.
However... it seems, though we can't be sure, that it's very good at persisting as a population.
Um... we, there are some indications to suggest that the population of the Nightcap Oak has not declined over the last.
Er... you know, many hundreds of years.
So it's stayed quite stable.
It's not a remnant of some huge population that is dwindled in last few hundred years for some reason.
It's not necessarily a species in retreat.
Ok, so it cannot spread very well, but it's good at maintaining itself.
It's rare, but it's not disappearing.
Ok, the next thing we might want to ask about the plant like that is what chances does it have to survive into the future.
Let's look at that. "
L6C2
"Listen to a conversation between a student and a professor.Professor Martin?
Uh, hi, Lisa, what can I do for you?
Well, I've been thinking about, you know, what you were saying in class last week, about how we shouldn't wait until the last minute to find an idea and get started working on our term paper.
Good, good, and have you come up with anything?
Well, yeah, sort of.
See, I've never had a linguistics class before, so I was sort of... I mean, I was looking over the course description and a lot of the stuff you described there, I just don't know what it is talking about, you know, or what it means.
But there was one thing that really did jump out at me.
Yes?
The section on dialects, 'cause ...like, that's the kind of thing that's always sort of intrigued me, you know?
Well, that's certainly an interesting topic.
But you may not realize, I mean, the scope...
Well, especially now, 'cause I've got like one roommate who is from the south and another one from New York.
And we all talk like totally different, you know?
Yes, I understand. But...
But then I was noticing, like, we don't really get into this till the end of the semester, you know. So I...
So, you want some pointers where to go for information on the subject?
Well, you could always start by reading the chapter in the book on sociolinguistics.
That will give you a basic understanding of the key issues involved here.
Yeah, that's what I thought.
So I started reading the chapter, you know, about how everyone speaks some dialect of a language.
And I'm wondering like, well, how do we even manage to understand each other at all?
Ah, yes, an interesting question. You see...
So then I read the part about dialect accommodation.
You know, the idea that people tend to adapt their speaking to make it closer to the speech of whomever they're talking to, and I'm thinking, yeah, I do that when I talk with my roommates, and without even thinking about it or anything, you know.
OK, all right. Dialect accommodation is a more manageable sort of topic.
So I was thinking like, I wonder just how much other people do the same thing.
I mean, there are students here from all over the place.
Does everyone change the way they talk to some degree depending on whom they are talking to?
You'd be surprised.
So, anyway, my question is, do you think it'd be OK if I did a project like that for my term paper?
You know, find students from different parts of the country, record them talking to each other in different combinations, report on how they accommodate their speech or not, that kind of thing?
Tell you what, Lisa, write me up a short proposal for this project, how you're going to carry out the experiment and everything, a design plan.
And I think this'll work out just fine. "
L6L3
"Listen to part of a lecture in a creative writing class.Alright everybody, the topic for today is, well, we're gonna take a look at how to start creating the characters for the story you're writing.
One way of doing that is to come up with what's called ""a character sketch"", I don't mean a sketch like a drawing, I guess that's obvious.
It's um... it's a... a sketch as a way of getting started on defining your characters' personalities.
To begin, how do we create fictional characters?
We don't just pull them from thin air, do we?
I mean we don't create them out of nothing.
We base them, consciously or unconsciously, we base them on real people, or we blend several people's traits, their attributes into one character.
But when people think fiction, they may assume the characters come from the author's imagination.
But the writer's imagination is influenced by... by real people, could be anyone.
So, pay attention to the people you meet, someone in class, at the gym, that guy who is always sitting in the corner of the coffee house, um... your cousin, who's always getting into dangerous situations.
We're pulling from reality, gathering bits and pieces of real people.
You use these people, and the bits of behavior or characteristics as a starting point as you begin to sketch out your characters.
Here is what you should think about doing first.
When you begin to formulate a story, make a list of interesting people you know or have observed.
Consider why they're unique or annoying.
Then make notes about their unusual or dominant attributes.
As you create fictional characters, you'll almost always combine characteristics from several different people on your list to form the identity and personality of just one character.
Keeping this kind of character sketch can help you solidify your character's personality, so that it remains consistent throughout your story.
You need to define your characters, know their personalities so that you can have them acting in ways that are predictable, consistent with their personalities.
Get to know them like a friend, you know your friends well enough to know how they'll act in certain situations, right?
Say you have three friends, their car runs out of gas on the highway.
John gets upset. Mary remains calm. Teresa takes charge of handling the situation.
And let's say,both John and Mary defer to her leadership.
They call you to explain what happened.
And when John tells you he got mad, you're not surprised, because he always gets frustrated when things go wrong.
Then he tells you how Teresa took charge, calmed him down, assigned tasks for each person and got them on their way.
Again, you're not surprised. It's exactly what you'd expect.
Well, you need to know your characters, like you know your friends.
If you know a lot about the person's character, it's easy to predict how they'll behave.
So if your character's personalities are well-defined, it will be easy for you as the writer to portray them realistically... er... believably, in any given situation.
While writing character sketches, do think about details.
Ask yourself questions, even if you don't use the details in your story, um... what does each character like to eat, what setting does each prefer, the mountains, the city, what about educational background, their reactions to success or defeat, write it all down.
But, here I need to warn you about a possible pitfall.
Don't make you character into a stereotype.
Remember the reader needs to know how your character is different from other people who might fall in the same category.
Maybe your character loves the mountains and has lived in a remote area for years.
To make sure he is not a stereotype, ask yourself how he sees life differently from other people who live in that kind of setting.
Be careful not to make him into the cliché of the ""ragged mountain dweller"".
Okay, now, I'll throw out a little terminology.
It's easy stuff.
Major characters are sometimes called ""round characters"".
Minor characters are sometimes called, well, just the opposite, ""flat"".
A round character is fully developed; a flat character isn't, character development is fairly limited.
The flat character tends to serve mainly as a motivating factor.
For instance, you introduce a flat character who has experienced some sort of defeat.
And then your round, your main character who loves success and loves to show off, comes and boasts about succeeding and jokes about the flat character's defeat in front of others, humiliates the other guy.
The flat character is introduced solely for the purpose of allowing the round character to show off. "
L6L4
"Listen to part of a lecture in an earth science class.We're really just now beginning to understand how quickly drastic climate change can take place.
We can see past occurrences of climate change that took place over just a few hundred years.
Take uh... the Sahara Desert in Northern Africa.
The Sahara was really different 6,000 years ago.
I mean, you wouldn't call it a tropical paradise or anything, uh... or maybe you would if you think about how today in some parts of the Sahara it... it only rains about once a century.
Um... but basically, you had greenery and you had water.
And what I find particularly interesting and amazing really, what really indicates how un-desert-like the Sahara was thousands of years ago was something painted on the rock, pre-historic art, hippopotamuses.
As you know hippos need a lot of water and hence? Hence what?
They need to live near a large source of water year round.
That's right.
But how is that proved that the Sahara used to be a lot wetter?
I mean the people who painted those hippos, well, couldn't they have seen them on their travels?
Okay, in principle they could, Karl. But the rock paintings aren't the only evidence.
Beneath the Sahara are huge aquifers, basically a sea of fresh water, that's perhaps a million years old filtered through rock layers.
And... er... and then there is fossilized pollen, from low shrubs and grasses that once grew in the Sahara.
In fact these plants still grow, er... but hundreds of miles away, in more vegetated areas.
Anyway, it's this fossilized pollen along with the aquifers and the rock paintings, these three things are all evidence that the Sahara was once much greener than it is today, that there were hippos and probably elephants and giraffes and so on.
So what happened?
How did it happen?
Now, we're so used to hearing about how human activities are affecting the climate, right?
But that takes the focus away from the natural variations in the earth climate, like the Ice Age, right?
The planet was practically covered in ice just a few thousand years ago.
Now as far as the Sahara goes, there is some recent literature that points to the migration of the monsoon in that area.
Huh?
What do I mean?
Okay, a monsoon is a seasonal wind that can bring in a large amount of rainfall.
Now if the monsoon migrates, well, that means that the rains move to another area, right?
So what caused the monsoon to migrate?
Well, the answer is: the dynamics of earth's motions, the same thing that caused the Ice Age by the way.
The earth's not always the same distance from the sun, and it's not always tilting toward the sun at the same angle.
There are slight variations in these two parameters.
They're gradual variations but their effects can be pretty abrupt.
And can cause the climate to change in just a few hundred years.
That's abrupt?
Well, yeah, considering that other climate shifts take thousands of years, this one is pretty abrupt.
So these changes in the planet's motions, they called it ""the climate change"".
But it was also compounded.
What the Sahara experienced was um... sort of ""runaway drying effect"".
As I said the monsoon migrated itself, so there was less rain in the Sahara.
The land started to get drier, which in turn caused huge decrease in the amount of vegetation, because vegetation doesn't grow as well in dry soil, right?
And then, less vegetation means the soil can't hold water as well, the soil loses its ability to retain water when it does rain.
So then you have less moisture to help clouds form, nothing to evaporate for cloud formation.
And then the cycle continues, less rain, drier soil, less vegetation, fewer clouds, less rain etc. etc..
But, what about the people who made the rock paintings?
Good question. Well, no one really knows.
But there might be some connections to ancient Egypt.
At about the same time that the Sahara was becoming a desert... hmm... 5,000 years ago, Egypt really began to flourish out in the Nile River valley.
And that's not that far away.
So it's only logical to hypothesize that a lot of these people migrated to the Nile valley when they realized that this was more than a temporary drought.
And some people take this a step further.
And that's okay, that's science and they hypothesize that this migration actually provided an important impetus in the development of ancient Egypt.
Well, we'll stay tuned on that. "
L7C1
"Listen to a conversation between a student and a professor.Hi, Professor Mason, do you have a minute?
Yes, of course, Eric, I think there was something I wanted to talk to you about too.
Probably my late essay.
Ah, that must be it, I thought maybe I'd lost it.
No, I'm sorry. Actually it was my computer that lost it, the first draft of it.
And, well, anyway, I finally put it in your mail box yesterday.
Oh, I haven't checked the mail box yet today.
Well, I'm glad it's there. I will read it this weekend.
Well, sorry again. Say, I can send it to you by email too if you like.
Great. I'll be interested to see how it all came out.
Right. Now, ah, I just have overheard some graduates students talking.
Something about a party for Dean Adams?
Retirement party, yes, all students are invited.
Wasn't there notice on the Anthropology Department's bulletin board?
Ah, I don't know. But I want to offer to help out with it.
You know whatever you need.
Dean Adams, well, I took a few anthropology classes with her and they were great, inspiring.
That's why I want to pitch in.
Oh, that's very thoughtful of you, Eric, but it will be pretty low-key, nothing flashy. That's not her style.
So there's nothing?
No, we'll have coffee and cookies, maybe a cake.
But actually a couple of the administrative assistants are working on that.
You could ask them but I think they've got it covered.
OK.
Actually, oh, no, never mind.
What's it?
Well, it's nothing to do with the party and I'm sure there are more exciting ways you could spend your time.
But we do need some help with something.
we‘re compiling a database of articles the anthropology faculty has published.
There is not much glory in it , but we are looking for someone with some knowledge of anthropology who can enter the articles.
I hesitate to mention it, but I don't suppose it's something you would...
No, that sounds kind of cool.
I would like to see what they are writing about.
Wonderful. And there are also some unpublished studies.
Did you know Dean Adams did a lot of field research in Indonesia?
Most of it hasn't been published yet.
No, like what?
Well, she is really versatile.
She just spent several months studying social interactions in Indonesia and she's been influential in ethnology.
Oh, and she's also done work in south of America, this is closer to biology, especially with speciation.
Ah, not to seem uninformed.
Well, how's species form? You know, how two distinct species form from one.
Like when populations of the same species are isolated from each other and then developed into two different directions and ended up with two distinct species.
Interesting.
Yes,and while she was there in the south of America, she collected a lot of linguistic information and songs, really fascinating.
Well. I hate to see her leave.
Don't worry. She'll still be around. She's got lots of projects that she's still in the middle of. "
L7L1
"Listen to part of a lecture in a class on theater history.The professor is discussing the theater of 19th-century France .
The 19th century was the time of thought what we called: Realism, developing in European theater.
Um, to understand this though, we first need to look at an earlier form of drama known as the well-made play, which basically was a pattern for constructing plays, plays that... uh... beginning with some early 19th century comedies in France proved very successful commercially.
The dramatic devices used here weren't actually anything new, they have been around for centuries.
But the formula for well-made play required that the certain of these elements being included, in a particular order, and most importantly, that everything in the play be logically connected.
In fact, some of the playwrights would start by writing the end of the play.
And work backward toward the beginning, just to make sure each event led logically from what had gone before.
Ok, so what are the necessary elements of a well-made play?
Well, the first is logical exposition.
Exposition is whatever background information you have to reveal to the audience.
So, they'll understand what is going on.
Before this time, exposition might come from the actors simply giving speeches.
Someone might walk out on the stage and say:""In fair Verona where we lay our scene!"".
And then tell all about the feuding families of Romeo and Juliet, but for the well-made play, even the exposition had to be logical, believable.
So, for example, you might have two servants gossiping as they are cleaning the house.
And one says, Oh, what a shame the master's son is still not married.
And the other might mention a rumor about a mysterious gentleman who just moved into the town with his beautiful daughter.
These comments are part of the play's logical exposition.
The next key element of the well-made play refer to as the inciting incident.
After we have the background information, we need a key moment to get things moving, they really makes the audience interested in what happens to the characters we just heard about.
So, for example, after the two servants reveal all this background information, we need the young man.
Just as he first lays eyes on the beautiful young woman, and he immediately falls in love.
This is the inciting incident.
It sets off, the plot of the play.
Now, the plot of a well-made play is usually driven by secrets.
Things, the audience knows, but the characters often don't know.
So, for example, the audience learned through a letter or through someone else's conversation
Who this mysterious gentleman is, and why he left the town many years before.
But the young man doesn't know about this.
And the woman doesn't understand the ancient connection between her family and his.
And before the secrets are revealed to the main characters, the plot of the play proceeds as a series of sort of up and down moments.
For example, the woman first appears not to even notice the young man, and it seems to him like the end of the world.
But then, he learns that she actually wants to meet him too. So, life is wonderful.
Then, if he tries to talk with her, maybe her father gets furious, for no apparent reason.
So, they can‘t see each other.
But, just as the young man has almost lost all hope, he finds out, well you get the idea, the reversals of the fortune continue, increasing the audience's tension and excitement,
making them wonder if everything is going to come out okay or not.
Next comes an element known as the: An obligatory scene.
It's a scene, a moment in which all the secrets are revealed.
In generally, things turn out well for the hero and others we care about, a happy ending of some sorts.
This became so popular that the playwright almost had to include it in every play, which is why it's called: the obligatory scene.
And that's followed by the final dramatic element---the denouement or the resolution, when all the loose ends have to be tied up in a logical way.
Remember, the obligatory scene gives the audience emotional pleasure.
But the denouement offers the audience a logical conclusion.
That's the subtle distinction we need to try very hard to keep in mind.
So, as I said, the well-made play, this form of play writing, became the basis for realism in drama, and for a lot of very popular 19th-century plays.
And also, a pattern we find in the plots of many later plays, and even movies that we see today. "
L7L2
"Listen to part of a lecture in a biology class.So, that is how elephant uses infrasound.
Now, let's talk about the other end of the acoustical spectrum, sound that is too high for humans to hear.
Ultrasound is used by many animals that detect and some of them send out very high frequency sounds.
So, what's a good example?
Yes, Carol. Well, bats, since they are all blind, bats have to use sound for, you know, to keep from flying into things.
That's echolocation.
Echolocation is pretty self-explanatory, using echoes—reflected sound waves to locate things.
As Carol said ， bats used it for navigation and orientation.
And what else?Mike.
Well, finding food is always important and I guess not becoming food for other animals.
Right, on both counts.
Avoiding other predators, and locating prey, typically insects that fly around at night.
Now ,before I go on, let me just respond to something Kayo was saying--
this idea that bats are blind.
Actually, there are some species of bats, the ones that don't use echolocation that do rely on their vision for navigation, but it is true that for many bats,their vision is too weak to count on.
OK, so quick summary of how echolocation works.
The bats emit these ultrasonic pulses, very high pitch sound waves that we cannot hear.
And then, they analyze the echoes, how the waves bounce back.
Here, let me finish this diagram I started before the class.
So the bat sends out these pulses, very focused bursts of sound, and echoes bounce back.
You know, I don't think I need to draw on the echoes, your reading assignment for the next class; it has diagram shows this very clearly. So, anyway, as I were saying,
by analyzing these echoes, the bat can determine, say, if there is wall in a cave that needs to avoid, and how far away it is.
Another thing it uses the ultrasound to detect is the size and shape of objects.
For example, one echo they quickly identified is one they associate with moth, which is common prey for a bat, particularly a moth beating its wings.
However, moth happened to have major advantage over most other insects.
They can detect ultrasound; this means that when the bat approaches, the moth can detect the bat's presence.
So, it has time to escape to safety, or else they can just remain motionless.
Since, when they stop beating their wings, they will be much harder for the bat to distinguish from, oh a leaf or some other object.
Now, we have tended to underestimate just how sophisticated the abilities of animals that use ultrasound are.
In fact, we kind of assume that they were filtering a lot out.
The way a sophisticated radar system can ignore the echoes from the stationary objects on the ground.
Radar does this to remove ground clutter , information about hills or buildings that it doesn't need.
But bats, we thought they were filtering out this kind of information, because they simply couldn't
analyze it.But, it looks as if we were wrong.
Recently there was this experiment with trees and a specific species of bats.
A bat called: the laser spear-nosed bat.
Now, a tree should be a huge and acoustical challenge for bat, right?
I mean it got all kinds of surfaces with different shapes and angles.
So, well, the echoes from a tree are going to be a massive chaotic acoustic reflections, right, not like the echo from a moth.
So, we thought for a long time that bats stop their evaluation as simply that's a tree.
Yet, it turns out that bats or at least this particular species, cannot only tell that is a tree, but can also distinguish between,say, a pine tree, and a deciduous tree, like a maple or oak tree, just by their leaves.
And when I say, leaves, I mean pine needles too.
Any ideas on how it would know that?
Well, like with the moth, could it be their shape?
You are on the right track----
it's actually the echo of all the leaves as a whole
that matters. Now, think, a pine tree with all those little densely packed needles.
Those produced a large number of faint reflections in which... what’s called a ... smooth echo. The wave form is very even.
But an oak which has fewer but bigger leaves with stronger reflections, produces jagged wave form, or what we called a rough echo.
And these bats can distinguish between the two, and not just with trees, but with any echo that comes in a smooth or rough shape. "
L7C2
"Listen to a conversation between a student and a librarian.Hi, I am new here
I couldn't come to the student orientation and I'm wondering if you can give me a few quick pointers about the library.
I'd really appreciate it.
Sure. I'd be glad to.
What's your major area of study?
Latin American Literature.
OK. Well, over here's the section where we have language, literature and arts.
And if you go down stairs you will find history section.
Generally, the students who concentrate in Latin American literature find themselves researching in the history section a lot.
Um-hmm, you are right.
I am a transfer student and I've already done a year in another university so I know how the research can go.I spent a lot of time in history section.
So how long can I borrow books for?
Our loan period is a month.
Oh I should also mention that we have an inter-library loan service.
If you need to get hold a book that's not in our library, there's a truck that runs between our library and a few other public and university libraries in this area.
It comes around three times a week.
Hey, that's great!
At my last school, it can take really a long time to get the materials I needed.
So when I had a project, I had to make a plan way in advance.
This sounds much faster.
Another thing I was wondering is... is there a place where I can bring my computer and hook it up?
Sure. There is a whole area here on the main floor where you can bring a laptop and plug it in for power, but on top of that we also have a connection for the internet at every seat.
Nice, so I can do all the research I need to do right here in the library.
All I have the resources, all the books and the information I need right here in one place.
Yeah. That's the idea.
I am sure you'll need photocopiers too.
They are down the hallway to your left.
We have a system where you have to use copy card so you'll need to buy a card from the front desk.
You insert it into the machine and you're ready to make copies.
How much do you guys charge?
Seven cents a copy.
Hum, that is not too bad. Thanks.
Hum, where is the collection of rare books?
Rare books are up on the second floor.
They are in a separate room where the temperature is controlled, to preserve the old paper in them.
You need to get special permission to access them, and then you have to wear gloves to handle them ‘cause the oils in our hands, you know, can destroy the paper.
And gloves prevent that so we have a basket of gloves in the room.
Ok. Thanks.
I suppose that’s all I need to know.
You've been very helpful. Thanks.
Anytime. Bye
Bye. "
L7L3
"Listen to part of a lecture in an anthropology class.So we've been discussing 16th century native American life and today we're gonna focus on the Iroquois and Huron peoples.
They lived in the northeastern Great Lake region of north America.
Now, back then, their lives depended on the natural resourses of the forests especially the birch tree.
The birch tree can grow in many different types of soils and is prevalent in that area.
Now can anyone here describe the birch tree.
Um...they're tall and white,
the bark I mean.Yes, the birch tree has white bark and this tough protective out layer of the tree is white bark, is waterproof.
And this waterproof quality of the bark, always made it useful for making things like cooking containers and a variety of utensils.
And if you peel birch bark in the winter,we call it the winter bark, another layer a tougher inner layer of the tree,adheres to the bark, producing a stronger material.
So the winter bark was used for large utensils and containers.
Um,I know people make utensils out of wood, but utensils out of the tree bark.
Well birch bark is pliable and very easy to bend.
The native Americans would cut the bark and fold it into any shape they needed, then secure with cords until it dried.
They could fold the bark into many shapes.
So if they cooked in bowls made of birch bark, wouldn't that make the food taste funny?
Oh that's one of the great things about birch bark.
The taste of the birch tree doesn't get transferred to the food.
So it was perfect for cooking containers.
But the most important use of the bark by far was the canoe.
Since the northeast region of the north American is interconnected by many streams and water ways, water transportation by vessels like canoe was most essential.
The paths through the woods were often over-grown so water travel was much faster.
And here is what the native Americans did.
They would peel large sheets of the bark from the trees to form light-weight yet sturdy canoes.
The bark was stretched over frames made from tree branches, stitched together and sealed with resin.
You know that the sticky liquid that comes out of the tree?
And when it dries, it's watertight.
One great thing about this birch bark canoe was they could carry a large amount of cargo.
For example, a canoe weighing about 50 pounds could carry up to 9 people and 250 pounds of cargo.
Wow, but how far could they travel that way?
Well, like I said, the northeast region is interconnected by rivers and streams and the ocean at the coast.
The canoes allowed them to travel over a vast area that today we take a few hours to fly over.
You see the native Americans made canoes of all types, for travelling on small streams or on large open ocean waters.
For small streams they made narrow maneuverable boats well, while large canoes were needed for the ocean.
They could travel throughout the area, only occasionally having to portage, to carry the canoe over land of short distance, to another nearby stream.
And since the canoes were so light, this wasn't a difficult task.
Now how do you think this affected their lives?
Well, if they could travel so easily over such a large area, they could trade with people from other areas which i guess would lead them to form alliances.
Exactly, having an efficient means of transportation, well that helped the iroquois to form a federation, linked by natual water ways.
And this federation expanded from what's now southern Canada all the way south to Delaware River.
And this efficiency of the birch bark canoe also made an impression on the newcomer to the area.
French traders in the 17th century modeled their... well, they adopted the design of the Iroquois birch bark canoes and they found they could travel great distances,more 1500 km a month.
Now besides the bark, native Americans also use the wood of the birch tree.
The young trees were used to support for loggings, with the waterproof bark used as roofing.
Um branches were folded into snow shoes, and the native American people were all adept to runing very fast over the snow in these birch branch snow shoes which if you've ever tried to walk in the snow shoes, you know it wasn't easy. "
L7L4
"Listen to part of a lecture in a geology class.Last time we started to talk about glaciers and how these masses of ice form from crystallized snow.
And some of you were amazed at how huge some of these glaciers are.
Now even though it may be difficult to understand how a huge massive ice can move or flow, it's another word for it.
It's really no secret that glaciers flow because of gravity.
But how they flow, the way they flow needs some explaining.
Now the first type of glacier flow is called basal slip.
Basal slip or sliding, as it's often called, basically refers to the slipping or sliding of glacier across bedrock, actually across a thin layer of water on top of the bedrock.
Um, so, this process shouldn't be too hard to imagine.What happens is that the ice of the base of glacier is under a great deal of pressure,
the pressure coming from the weight of the overlying ice.
And you probably know that under pressure the melting temperature of water of the ice I mean, is reduced.
So ice at the base of the glacier melts, even though it's below zero degree Celsius.
And this results in a thin layer of water between the glacier and the ground, this layer of water reduces friction it's like a lubricant.
And it allows the glacier to slide or slip over the bedrock.
Ok, now the next type of movement we will talk about is called deformation.
You already know that ice is brittle.
If you hit it with hammer, it'll shatter like glass.
But ice is also plastic, it can change shape without breaking.
If you leave, for example, a bar of ice supported only at one end.
The end, the unsupported end will deform under its own weight, kind of flatten out at one end and get distorted,
deformed.......Think of deformation as a very slow oozing.Depending on the stresses on the glacier,
the ice crystal within it reorganize.
And during this reorganization, the ice crystals realign in a way that allows them to slide pass each other.
And so the glacier oozes down hill without any ice actually melting.
Now there are a couple of factors that affect the amount of deformation that takes place, or the speed of the glacier's movement.
For example, deformation is more likely to occur the thicker the ice is because of the gravity of the weight of the ice.
And temperature also plays a part here, in that cold ice does not move as easily as ice that is closer to the melting point.
In fact it's not too different from the way oil is, thicker at lower temperatures.
So,if you have the glacier in a slightly warmer region it will flow faster than the glacier in a cooler region.
OK, um, now I'd like to touch briefly on extension and compression.
Your textbook includes this as types, as a particular type of glacier movement.
But you'll see that there are as many textbooks that omitted it as a type of movement as include it.
And I might not include it right now if it weren't in your textbook.
But um, basically, the upper parts of glaciers have less pressure on them.
So they don't deform easily, they tend to be more brittle.
And crevasses can form in this upper layers of the glacier, when the glacier comes into contact with bedrock walls or is otherwise under some kind of stress but can't deform quickly enough.
So the ice would expand or constrict.
And that can cause big fissures big cracks to form in the surface layers of ice.
And that brittle surface ice moving,is sometimes considered a type of glacier movement,depending on which source you are consulting.
Now as you probably know, glaciers generally move really slowly, but sometimes, they experience surges, and during these surges, in some places, they can move at speeds as high as 7,000 meters per year.
Now speeds like that are pretty unusual.
Hundreds of times faster than the regular movement of glaciers,but you can actually see glacier's move during the surges, though it is rare. "
L8C1
"Listen to a conversation between a student and a registrar.Hi, I'd like to drop off my graduation form.
I understand you need this in order to process my diploma.
Ok, I will take that. Before you leave, let me check our computer.
Looks like you are OK for graduation, and actually, I am getting a warning flag on your academic record here.
Really?
Yeah. Let's see what's what.
Ok,Are you familiar with your graduation requirements?
UH HUH，I think so.
Well, then you know you need 48 credits in your major field to graduate and at least 24 credits in the intermediate level or higher.
Also, after your second year, you have to meet with your department chair to outline a plan for the rest of your time here.
In the past, we also issue letters before students' final year began to let them know what they needed to take in the final year to be OK, but we don't do that anymore.
I definitely met with my chair person two years ago.
He told me that I need 8 more courses at the intermediate level or higher in the last two years to be OK.
So I am not sure what the problem is.
I make sure I got those credits.
Unfortunately, the computer is usually pretty reliable.
So, I am not sure what's going on here.
It could be that I have taken two basic courses but coupled both of them with a field experiences.
What do you mean?
Well, I could only take intro courses because there were no intermediate level courses available for those particular topics.
My chair person told me that if I did the independent field research in addition to the assigned work in each course, they would count as intermediate level courses.
My classmates, some of my classmates, did this for an easy way to meet their intermediate course requirement, but I did it to get the kind of depth in those topics I was going for.
As it turned out I really enjoyed the field work, it was a nice supplement to just sitting and listening to lectures.
I am sure that's true, but the computer is still showing them as basic level courses despite the field work.
I am not sure what to do then, I mean, should I cancel my graduation party?
No, no reason to get worried like that, just contact your chair person immediately, OK?
Tell him to call me as soon as possible so that we can verify your field work arrangement and certify those credits right away.
It's not like there is an actual deadline to date or anything.
But if more than a few weeks go by, we might have a real problem that would be very difficult to fix in time for you to graduate.
In fact, there probably would be nothing we could do.
I will get on that. "
L8L1
"Listen to part of a lecture in an animal behavior class.OK, well, last time we talked about passive habitat selection, like plants for example, they don't make active choices about where to grow.
They are dispersed by some other agent, like the wind.
And if the seeds land in a suitable habitat, they do well and reproduce.
With active habitat selection, an organism is able to physically select where to live and breed.
And because an animal's breeding habitat is so important, we'd expect animal species to have developed preferences for particular types of habitats, places where their offspring have the best chance of survival.
So let's look at the effect these preferences can have by looking at some examples, but first let's recap.
What do we mean by habitat? Frank?
Well, it's basically the place or environment where an organism normally lives and grows.
Right, and as we've discussed, there are some key elements that a habitat must contain, food obviously, water, and it's got to have the right climate and spaces for physical protection.
And we saw how important habitat selection is when we look at the habitats where some of these factors are removed, perhaps through habitat destruction.
I just read about a shorebird, the plover.
The plover lives by the ocean and feeds on small shellfish, insects and plants.
It blends in with the sand, so it's well-camouflaged from predator birds above.
But it lays its eggs in shallow depressions in the sand with very little protection around them.
So if there are people or dogs on the beach, the eggs and fledglings in the nests are really vulnerable.
Out in California where there has been a lot of human development by the ocean.
The plovers are now a threatened species.
So conservationists tried to create a new habitat for them.
They made artificial beaches and sand bars in areas inaccessible to people and dogs.
And the plover population is up quite a bit in those places.
Ok. That is an instance where a habitat is made less suitable.
But now, what about cases where animal exhibits a clear choice between two suitable habitats ?In cases like that,
Dose the preference matter? Well, Let's look at the blue warbler.
The Blue warbler is a songbird that lives in North America.
They clearly prefer hard wood forests with dense shrubs, bushes underneath the trees.
They actually nest in the shrubs, not the trees.
So they're pretty close to the ground, but these warblers also nest in the forests that have low shrub density.
It is usually the younger warblers that nest in these areas because the preferred spots where there are a lot of shrubs are taken by the older more dominant birds.
And the choice of habitat seems to affect the reproductive success.
Because the older and more experienced birds who nest in the high density shrub areas have significantly more offspring than those in low density areas, which suggests that the choice of where to nest does have an impact on the number of chicks they have.
But a preferred environment doesn't always seem to correlate with greater reproductive success.
For example, in Europe, studies have been done of blackcap warblers.
We just call them blackcaps.
The Blackcap can be found in two different environments.
Their preferred habitat is forests near the edge of streams.
However, blackcaps also live in pine woods away from water.
Studies have been done on the reproductive success rates for the birds in both areas, and the result showed surprisingly that the reproductive success was essentially the same in both areas - the preferred and the second choice habitat.
Well. Why?
It turned out that there were actually four times as many bird pairs or couples living in the stream edge habitat compared to the area away from the stream.
So this stream edge area had a much denser population which meant more members of the same species competing for resources, wanting to feed on the same things or build their nests in the same places, which lower the suitability of the prime habitat even though it's their preferred habitat.
So the results of the study suggest that when the number of the competitors in the prime habitat reaches a certain point, the second rank habitat becomes just as successful as the prime habitat, just because there are fewer members of the same species living there.
So it looks like competition for resources is another important factor in determining if a particular habitat is suitable. "
L8L2
"Listen to part of a lecture in an art history class.We had been talking about the art world of the late 19th century in Paris.And today I'd like to look at the women who went to Paris at that time to become artists.
Now from your reading what do you know about Paris, about the art world of Paris during the late 19th century?
People came there from all over the world to study.
It had a lot of art schools and artists who taught painting.
There were, our book mentions classes for women artists.
And it was a good place to go to study art.
If you wanted to become an artist, Paris was not a good place to go, Paris was THE place to go.
And women could find skilled instructors there.
Before the late 19th century, if they, women who wanted to become artists had to take private lessons or learn from family members.
They had more limited options than men did.
But around 1870s, some artists in Paris began to offer classes for female students.
These classes were for women only.
And by the end of the 19th century, it became much more common for women and men to study together in the same classes.
So within a few decades, things had changed significantly.
Ok. Let's back up again and talk about the time period from the 1860s to the 1880s and talk more about what happened in women's art classes.
In 1868, a private art academy opened in Paris, and for decades. it was probably the most famous private art school in the world
Its founder Rodolphe Julian was a canny businessman.
And quickly established his school as a premier destination for women artists.
What he did was:After an initial trial period of mixed classes, he changed the school policy.
He completely separated the men and women students.
Any reason why he did that?
Well. Like I said Julian was a brilliant businessman, with progressive ideas.
He saw that another small private art school where all the students were women was very popular at that time.
And that's probably why he adopted the women-only classes.
His classes were typically offered by ....by established artists and were held in the studio, the place where they painted.
This was a big deal because finally women could study art in a formal setting.
And there was another benefit to the group setting of these classes.
The classes included weekly criticism.
And the teacher would rank the art of all the students in the class from best to worst.
How would you like it if I did that in this class?
Hah......no way.
But our textbook said that the competitive， the competition was good for women.
It helped them see where they needed to improve.
Isn't that interesting?One woman artist, her name was Marie Bashkirtseff.
Bashkirtseff once wrote how she felt about a classmate's work.
She thought her classmates' art was much better than her own and it gave her an incentive to do better.
Overall, the competition in the women's art classes gave women more confidence.
Confidence that they could also compete in the art world after their schooling.
And even though Bashkirtseff could not study in the same classes as men, she was having an impact as an artist.
Just look at the salon, what do you know about the salon?
It was a big exhibition, a big art show that they had in Pairs every year.
Their art had to be accepted by judges.
It was a big deal you can make a name for yourself.
You can have a painting or sculpture in the salon and go back to your home country saying you've been a success in the Paris.
It was sort of uh, a seal of approval.
It was a great encouragement for an artist's career.
By the last two decades of 19 century, one fifth of the paintings in the salon were by woman, much higher than in the past.
In fact, Marie Bashkirtseff self had a painting in the salon in 1881.
Interestingly this masterpiece called In the Studio is a painting of the interior of Julian's art school.
It is not in your textbook I will show you the painting next week.
The painting depicts an active crowded studio with women drawing and painting a live model.
It was actually Bashkirtseff actually follow Julian's savvy suggestion and painted her fellow students in a class at the school with the artist herself at far right.
A great advertisement for the school when the painting eventually hung up at the salon, for a women's studio had never been painted before. "
L8C2
"Listen to a conversation between a student and a business professor.So, Richer, what's up?
Well, I know we have a test coming up on chapters.
Chapter 3 and 4 from your text book.
Right, 3 and 4, well, I didn't get something you said on class Monday.
Alright? Do you remember what it was about?
Yes, you were talking about a gym... a health club where people can go to exercise that kind of thing.
OK, but the health club model is actually from chapter 5... so...
Oh, chapter 5? Oh so it's not... OK but I guess I still want to try to understand...
Of course, I was talking about an issue in strategic marketing, the health club model.
I mean with a health club you might think they would have trouble attracting customers, right?
Well, I know when I pass by a healthy club and I see others people working out, the exercising, I just soon walk on by.
Yeah, there is that.
Plus, lots of people have exercise equipment at home, or they can play sports with their friends. Right?
Sure.
But nowadays in spite of all that, and expensive membership fees, health club are hugely popular, so how come?
I guess that is what I didn't understand.
OK, basically they have to offer things that most people can't find anywhere else, you know quality, that means better exercise equipment, high-end stuff, and classes-exercise classes may be aerobics.
I am not sure if I... ok I get it.
Yeah，and you know another thing is I think people probably feel good about themselves when they are at gym.
And they can meet new people socialize.
Right, so health clubs offer high quality facilities, and also they sell an image about people having more fun, relating better to others and improving their own lives if they become members.
Sure that makes sense.
Well, then, can you think of another business or organization that could benefit from doing this?
Think about an important building on campus here, something everyone uses, a major source of information?
You mean like an administrative building?
Well, that is not what I had in my mind.
Oh, You mean the library.
Exactly. Libraries. Imagine public libraries.
There are information resource for the whole community, right?
Well, they can be. But, now, with the internet and big book stores, you can probably get what you need without going to a library.
That's true. So if you were the director of a public library, what would you do about that?
To get more people to stop in?
Well, like you said, better equipment, maybe a super fast internet connection.
And not just a good variety of books but also like nice and comfortable areas where people can read and do research - things that make them want to come to the library and stay.
Great.
Oh, and maybe have authors come and do some readings or, I don't know, special presentations - something people couldn't get at home.
Now, you are getting it.
Thanks, professor Wilkins. I think so, too. "
L8L3
"Listen to part of a lecture in a history class.So we've been talking about the printing press.
How it changed people's lives, making books more accessible to everyone.
More books meant more reading, right?
But, as you know, not everyone has perfect vision.
This increasing literacy, um, in reading, led to an increasing demand for eye glasses.
And here's something you probably haven't thought of.
This increased demand impacted the societal attitudes toward eye glasses.
But, first let me back up a bit and talk about vision correction before the printing press.
And, um, what did people with poor vision do, I mean, especially those few people who were actually literate?
What did they do before glasses were invented?
Well, they had different ways of dealing with not seeing well.
If you think about it, poor vision wasn't their only problem, I mean, um, think about the conditions they lived in: houses were dark, sometimes there weren't any windows; candles were the only source of light.
So in some places, um, like ancient Greece for example, the wealthiest people with poor vision could have someone else read to them - easy solution if you could afford it.
Another solution was something called a ""reading stone"".
Around 1000 C.E. European monks would take a piece of clear rock, often quartz, and place it on top of the reading material.
The clear rock magnified the letters, making them appear larger, um, looks like what happens when a drop of water falls on something, whatever's below the drop of water appears larger, right?
Well, the ""reading stone"" works in a similar way.
But rocks like quartz, well, quartz of optical quality weren't cheap.
Late in the 13th century, glass maker in Italy came up with a less expensive alternative.
They made reading stones out of clear glass.
And these clear glass reading stones evolved into the eye glasses we know today.
So we're pretty sure that glasses were invented in about the late 1200's, well, over a hundred years before the printing press.
But it's not clear who exactly invented them first or exactly what year.
But record shows that they were invented in both Europe and China at about the same time.
By the way, we call this ""independent discovery"".
Independent discovery means when something is invented in different parts of the world at the same time and it's not as unusual as it sounds.
You can look at the timeline charts at the back of your textbook to see when things were invented in different cultures at about the same time to see what I'm talking about.
So now let's tie this to what I've said before about societal attitude towards glasses.
Initially in parts of Europe and in China, glasses were a symbol of wisdom and intelligence.
This is evident in the artwork from the period.
European paintings often portrayed doctors or judges wearing glasses.
In China, glasses were very expensive, so in addition to intelligence, they also symbolize affluence, um, wealth.
In 14th century Chinese portraits, the bigger the glasses, the smarter and wealthier the subject was.
So glasses were a status symbol in some parts of the world.
Now let's go back to the invention of the printing press in 1440.
What happened? Suddenly, books became readily available and more people wanted to read.
So the need, oh well, actually not only the need but the demand for more affordable glasses rose drastically.
Eventually, inexpensive glasses were produced, and then glasses were available to everyone.
People could purchase them easily from a traveling peddler. "
L8L4
"Listen to part of a lecture in the chemistry class. The professor has been discussing the periodic table of elements.So are there any questions?
Yes, em, professor Harrison, you were saying that the periodic table is predictive.
What exactly does that mean?
I mean I understand how it organizes the elements but where is the prediction?
OK, let's look at periodic table again.
OK, it groups elements into categories that share certain properties, right?
Um-huh~
And it's arranged according to increasing atomic number, which is..
The number of protons in each atom of an element.
Right, well, early versions of the periodic table had gaps, missing elements.
Every time you had one more proton, you had another element, and then, oops, there have been atomic number, for which there is no known element, and the prediction was that the elements, with that atomic number existed somewhere, but it just hadn't been found yet.
And its location in the table would tell you what properties it should have.
It was really pretty exciting for scientists at that time to find these missing elements and confirm their predictive properties.
Um, actually, that reminds me of other very good example of all these, element 43.
See on the table, the symbols for element 42 and 44.
Well, in early versions of the table, there was no symbol for element 43 protons because no element with 43 protons had been discovered yet.
So the periodic table had a gap between elements 42 and 44.
And then, in 1925, a team of chemists led by a scientist named Ida Tack claimed that they had found element 43.
They had been using a relatively new technology called ""X-rays spectroscopy"", and they were using this to examine an ore sample, and they claimed that they'd found an element with 43 protons and they named it Masurium.
Um, professor Harrison, then, how come in my periodic table, here, element 43 is TC, that's technetium, right?
OK, let me add that.
Actually, um, that's the point I'm coming to.
Hardly anyone believed that Tack has discovered the new element.
X-ray spectroscopy was a new method at that time.
And they were never able to isolate enough Masurium to have weighable sample to convince everyone of the discovery.
So they were discredited.
But then, 12 years later in 1937, a different team became the first to synthesize the element using a cyclotron, and that element had...
43 Protons?
That's right, but they named it Technetium to emphasize that it was artificially created with technology.
And people thought that synthesizing this element, making it artificially was the only way to get it.
We still haven't found it currently in nature.
Now, element 43 what they called Masurium or Technetium is radioactive.
Why is that matter? What's true of radioactive element?
It decays, it turns into other elements?
Oh, so does that explain why it was missing in the periodic table?
Exactly. Because of its radioactive decay, element 43 doesn't last very long.
And therefore, if it ever had been present on earth, it would have decayed ages ago.
So the Masurium people were obviously wrong, and the Technetium people were right, right?
Well, that was then, now we know that element 43 does occur naturally.
It can be naturally generated from Uranium atom that has spontaneously split.
And guess what?
The ore sample the Masurium group was working with had plenty of Uranium in it, enough to split into measurable amounts of Masurium.
So Tack's team might very well have found small amounts of Masurium in the ore sample.It's just that once it was generated from split Uranium it decayed very quickly.
And you know, here is an incredible irony.
Ida Tack, the chemist led the Masurium team, when she was the first to suggest that Uranium could break up into smaller pieces but she didn't know that that was the defense of her own discovery of element 43.
So is my version of the periodic table wrong?
Should element 43 really be called Masurium?
Maybe, but you know it‘s hard to tell for sure after all this time, if Ida Tack’s group did discover element 43.
They didn't, um, publish enough detail on their methods or instruments for us to know for sure.
But I'd like to think that element 43 was discovered twice, as Masurium, it was the first element discovered that occurs in nature only from spontaneous fission, and as Technetium, it was the first element discovered in laboratory.
And of course, it was an element the periodic table let us to expect existed before anyone had found it or made it. "
L9C1
"Listen to a conversation between a student and her professor.Before we get started, I... I just wanted to say I'm glad you chose food science for your major courses study.
Yeah, it seems like a great industry to get involved with.
I mean with the four-year degree in food science, I'll always be able to find a job.
You're absolutely right. Before entering academia, I worked as a scientist for several food manufacturers and for the US Food and Drug Administration.
I even worked on a commercial fishing boat in Alaska a couple of summers while I was an undergraduate.
We bring in the day's catch to a floating processor boat where the fish got cleaned, packaged and frozen right at sea.
That's amazing!
As a matter of fact, I'm sort of interested in food packaging.
Well, for that, you'll need a strong background in physics, math and chemistry.
Those are my best subjects.
For a long time, I was leading towards getting my degree in engineering.
Well, then you shouldn't have a problem.
And fortunately, at this university, the department of food science offers a program in food packaging.
Elsewhere, you might have to hammer courses together on your own.
I guess I luck out then.
Um... so since my appointment today is to discuss my term paper topic, I wanted to ask, could I write about food packaging?
I realize we're supposed to research food-borne bacteria, but food packaging must play a role in all of that, right?
Absolutely! Maybe you should do some preliminary research on that.
I have! That's the problem, I'm overwhelmed.
Well, in your reading, did anything interest you in particular?
I mean something you'd like to investigate.
Well, I was surprised about the different types of packaging used for milk.
You know, clear plastic bottles, opaque bottles, cardboard containers...
True! In fact, the type of packaging has something to do with the way milk's treated against bacteria.
Yeah, and I read a study that showed how light can give milk a funny flavor and decrease the nutritional value.
And yet most milk bottles are clear.
What's up with that?
Well consumers like being able to visually examine the color of the milk.
That might be one reason that opaque bottles haven't really caught on.
But that study... I'm sure there is more studies on the subject.
You shouldn't base your paper on only one study.
Maybe I should write about those opaque plastic bottles.
Find out if there are any scientific reasons they aren't used more widely?
Maybe opaque bottles aren't as good at keeping bacteria from growing in milk after the bottle has been opened to something...
But where to begin researching this? I don't have a...
You know, there is a dairy not far from here in Chelsea.
It was one of the first dairies to bottle milk in opaque plastic, but now they're using clear plastic again.
And they're always very supportive of the university and our students, so if you want it...
Yeah, I like that idea. "
L9L1
"Listen to part of a lecture in a theater class.As we have seen, the second half of the 18th century was an exciting time in Europe: it was not only an age of great invention, but social changes also led to a rise in all sorts of entertainment, from reading to museums, to travel.
And finding himself in the middle of this excitement was an accomplished French painter named Philippe Jacques de Loutherbourg.
Loutherbourg arrived in England in 1771, and immediately went to work as a set designer at the famous Drury Lane Theater in London.
From his first shows, Loutherbourg showed a knack for imagination and stage design, all in the interest of creating illusions that allowed the audience to suspend disbelief completely.
He accomplished this by giving the stage a greater feeling of depth, which he did by cutting up some of the rigid background scenery, and placing it at various angles and distances from the audience.
Another realistic touch was using three-dimensional objects on the set, like rocks and bushes as opposed to two-dimensional painted scenery.
He also paid much more attention to lighting and sound than had been done before.
Now, these sets were so elaborate that many people attended the theater more for them than for the actors or the stories.
At the time, people were wild for travel and for experiencing new places, but not everyone could afford it.
Loutherbourg outdid himself however, with a show that he set up in his own home.
He called it the ""Eidophusikon"".
""Eidophusikon"" means something like representation of nature, and that's exactly what he intended to do: create realistic moving scenes that change before the audiences' eyes.
In this, he synthesized all his tricks from Drury Lane: mechanical motions, sound, light, other special effects to create, if you will, an early multimedia production.
The ""Eidophusikon"" was Loutherbourg's attempt to release painting from the constraints of the picture frame.
After all, even the most action-filled exciting painting can represent only one moment in time, and any illusion of movement is gone after the first glance.
But Loutherbourg, like other contemporary painters, wanted to add the dimension of time to his paintings.
You know, the popular thinking is that Loutherbourg was influenced by landscape painting.
But why can't we say that the ""Eidophusikon"" actually influenced the painters?
At the very least we have to consider that it was more... it was more of a mutual thing.
We know, for example, that the important English landscape painter Thomas Gainsborough attended almost all of the yearly performances, and his later paintings are notable for their increased color and dynamic use of light.
Loutherbourg's influence on the theater though, he was incredibly influential: the way he brought together design and lighting and sound as a unified feature of the stage, can easily be seen in English theater's subsequent emphasis on lighting and motion.
Now, the ""Eidophusikon"" stage was actually a box: a few meters wide, a couple meters tall and a couple meters deep.
That is, the action took place within this box.
This was much smaller of course than the usual stage.
But, it also allowed Loutherbourg to concentrate the lighting to better effect.
Also, the audience was in the dark, which wouldn't be a common feature of the theater until a hundred years later.
The show consisted of a series of scenes, for example, a view of London from sunrise that changes as the day moves on: mechanical figures, such as cattle, moved across the scene, and ships sailed along the river.
But what really got people was the attention to detail, much like his work in Drury Lane.
So, for example, he painted very realistic ships, and varied their size depending on their distance from the audience.
Small boats moved more quickly across the foreground than larger ones did that were closer to the horizon.
Other effects, like waves, were also very convincing.
They reflected sunlight or moonlight depending on the time of day or night.
Even the colors changed as they would in nature.
Sound and light were important in making his productions realistic.
He used a great number of lamps, and he was able to change colors of light by using variously colored pieces of glass, to create effects like passing clouds that suddenly change in color.
Furthermore, he used effects to make patterns of shadow and light, rather than using the uniform lighting that was common at the time.
And many of the sound effects he pioneered are still in use today, like creating thunder by pulling on one of the corners of a thin copper sheet.
One of his most popular scenes was of a storm.
And there is a story that on one occasion, an actual storm passed over head during the show.
And some people went outside, and they claimed Loutherbourg's thunder was actually better than the real thunder. "
L9L2
"Listen to a part of lecture in an environmental science class.So since we're on the topic of global climate change and its effects, in Alaska, in the northern Arctic part of Alaska, over the last ... oh...thirty years or so, temperature has increased about half a degree Celsius per decade, and scientists have noticed that there's been a change in surface vegetation during this time.
Shrubs are increasing in the ""tundra"".
Tundra is a flat land with very little vegetation.
Just a few species of plants grow there because the temperature is very cold, and there's not much precipitation.
And because of the cold temperature, the tundra has two layers: top layer, which is called the active layer, is frozen in the winter and spring, but thaws in the summer.
Beneath this active layer is the second layer called ""permafrost"", which is frozen all year around, and is impermeable to water.
So because of the permafrost, none of the plants that grow there can have deep roots, can they?
No, and that's one of the reasons that shrubs survive in the Arctic.
Shrubs are little bushes.
They're not tall and being low to the ground protect them from the cold and wind.
And their roots don't grow very deep, so the permafrost doesn't interfere with their growth. OK?
Now since the temperatures have been increasing in Arctic Alaska, the growth of shrubs has increased.
And this has presented to climate scientists with a puzzle...
I'm sorry, when you say the growth of shrubs has increased, do you mean the shrubs are bigger, or that there are more shrubs?
Good question! And the answer is both.
The size of the shrubs has increased and shrub cover has spread to what was previously shrub-free tundra.
Ok, so what's the puzzle?
Warmer temperatures should lead to increased vegetation growth, right?
Well, the connections are not so simple.
The temperature increase has occurred during the winter and spring, not during the summer.
But the increase in shrubs has occurred in the summer.
So how can increased temperatures in the winter and spring result in increased shrub growth in the summer?
Well, it may be biological processes that occur in the soil in the winter, that cause increased shrub growth in the summer, and here's how: there are ""microbes"", microscopic organisms that live in the soil.
These microbes enable the soil to have more nitrogen, which plants need to live and they remain quite active during the winter.
There're two reasons for this: first, they live in the active layer, which, remember, contains water that doesn't penetrate the permafrost; second, most of the precipitation in the Arctic is in the form of snow.
And the snow, which blankets the ground in the winter, actually has an insulating effect on the soil beneath it.
And it allows the temperature of the soil to remain warm enough for microbes to remain active.
So there's been increase in nutrient production in the winter.
And that's what's responsible for the growth of shrubs in the summer and their spread to new areas of the tundra.
Areas with more new nutrients are the areas with the largest increase in shrubs.
But, what about run-off in the spring, when the snow finally melts?
Won't the nutrients get washed away?
Spring thaw always washes way soil, doesn't it?
Well, much of the soil is usually still frozen during peak run-off.
And the nutrients are deep down in the active layer anyway, not high up near the surface, which is the part of the active layer most affected by run-off.
But as I was about to say, there's more to the story.
The tundra is windy, and the snow is blown across the tundra, it's caught by shrubs.
And deep snow drifts often form around shrubs.
And we've already mentioned the insulating effect of snow.
So that extra warmth means even more microbial activity, which means even more food for the shrubs, which means even more shrubs and more snow around etc.. It's a circle, a loop.
And because of this loop, which is promoted by warmer temperatures in winter and spring, well, it looks like the tundra may be turning into shrub land.
But will it be long term?
I mean maybe the shrubs will be abundant for a few years, and then it'll change back to tundra.
Well, shrub expansion has occurred in other environments, like semiarid grassland, and tall grass prairies.
And shrub expansion in these environments does seem to persist, almost to the point of causing a shift.
Once is established, shrub land thrives, particularly in the Arctic, because Arctic shrubs are good at taking advantage of increased nutrients in the soil, better than other Arctic plants. "
L9C2
"Listen to a conversation between a student and a librarian employee.Excuse me. Can you help me with something?
I'll do my best. What do you need?
Well, I've received a letter in my mailbox saying that I'm supposed to return a book that I checked out back in January.
It's called ""Modern Social Problems"".
But because I'm writing my senior thesis, I'm supposed to be able to keep the book all semester.
So you signed up for extended borrowing privileges?
Yeah.
But we are still asking you to bring the book back?
Uh-huh.
Well, let me take a look and see what the computer says.
The title was ""Modern Social Problems""?
Yeah.
OK. Um...Oh, I see, it's been recalled.
You can keep it all semester as long as no one else requests it. But, someone else has.
It looks like one of the professors in the sociology department requested it.
So you have to bring it back, even though you've got extended borrowing privileges.
You can check out the book again when it's returned in a couple of weeks.
But I really need this book right now.
Do you need all of it or is there a certain section or chapter you're working with?
I guess there is one particular chapter I've been using lately for a section of my thesis. Why?
Well, you can photocoping up to one chapter of the book.
Why don't you do that for the chapter you're working on right now?
And by the time you need the rest of the book, maybe it will have been returned.
We can even do the photocopy for you because of the circumstances.
Oh, well, that would be great.
I see you've got some books there.
Is that the one you were asked to return?
No, I left it in my dorm room.
These are books I need to check out today.
Is it OK if I bring that one by in a couple of days?
Actually, you need to return it today.
That is if you want to check out those books today. That's our policy.
Oh, I didn't know that.
Yeah, not a lot of people realize that.
In fact, every semester we get a few students who have their borrowing privileges suspended completely because they haven't returned books.
They're allowed to use books only in the library.
They're not allowed to check anything out because of unreturned books.
That's not good. I guess I should head back onto the dorm right now then.
But, before you go, what you should do is fill out a form requesting the book back in two weeks.
You don't want to waste any time getting it back.
Thanks a lot, now I don't feel quite so bad about having to return the book. "
L9L3
"Listen to part of a lecture in a geology class.So, continuing our discussion of desert lakes, now I want to focus on what's known as the ""Empty Quarter"".
The ""Empty Quarter"" is a huge area of sand that covers about a quarter of the Arabian Peninsula.
Today it's pretty desolate, barren and extremely hot.
But there've been times in the past when monsoon rains soaked the Empty Quarter, and turned it from a desert into grassland that was dotted with lakes and home to various animals.
There were actually two periods of rain and lake formation: the first one began about 37，000 years ago, and the second one dates from about 10，000 years ago.
Excuse me, Professor. But I'm confused.
Why would lakes form in the desert? It's just sand, after all.
Good question! We know from modern day desert lakes, like Lake Eyre in South Australia, that under the right conditions, lakes do form in the desert.
But the Empty Quarter lakes disappeared thousands of years ago.
They left behind their beds or basins as limestone formations that we can still see today.
They look like low-lying, white or grey builds, long, narrow hills with flat tops, barely a meter high.
A recent study of some of the formations presents some new theories about the area's past.
Keep in mind though that this study only looked at 19 formations.
And about a thousand have been documented.
So there's a lot more work to be done.
According to the study, two factors were important for lake formation in the Empty Quarter.
First the rains that fell there were torrential, so it would've been impossible for all the water to soak into the ground.
Second, as you know, sand dunes contain other types of particles, besides sand, including clay and silt.
Now, when the rain fell, water ran down the sides of the dunes, carrying clay and silt particles with it.
And wherever these particles settled, they formed a pan, a layer that water couldn't penetrate.
Once this pan formed, further run-off collected, and formed a lake.
Now, the older lakes, about half of the formations, the ones started forming 37000 years ago, the limestone formation we see, they're up to a kilometer long, but only a few meters wide, and they're scattered along the desert floor, in valleys between the dunes.
So, the theory is, the lakes formed there on the desert floor, in these long narrow valleys.
And we know, because of what we know about similar ancient desert lakes, we know that the lakes didn't last very long, from a few months to a few years on average.
As for the more recent lakes, the ones from 10000 years ago, well, they seemed to have been smaller, and so may have dried up more quickly.
Another difference, very important today for distinguishing between older lake beds and newer ones, is the location of the limestone formations.
The more recent beds are high up in the dunes.
Why these differences?
Well, there are some ideas about that, and they have to do with the shapes of the sand dunes, when the lakes were formed.
37000 years ago, the dunes were probably nicely rounded at the top, so the water just ran right down their sides to the desert floor.
But there were thousands of years of wind between the two rainy periods, reshaping the dunes.
So, during the second rainy period, the dunes were kind of chopped up at the top, full of hollows and ridges, and these hollows would've captured the rain right there on the top.
Now, in the grassland of Lake Ecosystem, we'd expect to find fossils from a variety of animals, and numerous fossils have been found at least at these particular sites.
But, where did these animals come from?
Well, the theory that has been suggested is that they migrated in from nearby habitats where they were already living.
Then as the lakes dried up, they died out.
The study makes a couple of interesting points about the fossils, which I hope will be looked at in future studies.
At older lake sites, their fossil remains from hippopotamuses, water buffalo, animals that spend much of their lives standing in water, and also, fossils of cattle.
However, at the sites of the more recent lakes, there're only cattle fossils, additional evidence for geologists that these lakes were probably smaller, shallower, because cattle only use water for drinking.
So they survive on much less.
Interestingly, there are clams and snail shells, but, no fossils of fish.
We're not sure why.
Maybe there is a problem with the water.
Maybe it was too salty.
That's certainly true of other desert lakes. "
L9L4
"Listen to part of a lecture in a linguistics class.The professor has been discussing Animal communication systems.
OK, so last time, we covered the dances honey bees do to indicate where food can be found and the calls and sounds of different types of birds.
Today, I'd like to look at some communication systems found in mammals, particularly in primates, such as orangutans, chimpanzees, gorillas... Yes, Thomas?
Excuse me, Professor. But when you talk about gorilla language, do you mean like, those experiments where humans taught them sign language or a language like...
OK, wait just a minute.
Now, who in this class heard me use the word ""language""? No one I hope.
What we're talking about here, are systems of communication, all right?
Oh, sorry, communication, right.
But could you maybe, like, clarify with the differences?
Of course, that's a fair question.
OK, well, to start with, let's make it clear that language is a type of communication, not the other way around.
OK, so all communication systems, language included, have certain features in common.
For example, the signals used to communicate from the bee's dance movements, to the word and sentences found in human languages.
All these signals convey meaning.
And all communication systems serve a purpose, a pragmatic function of some sort.
Warning of danger perhaps or offering other needed information.
But there're several features peculiar to human language that have, for the most part, never been found in the communication system of any other species.
For one thing, learn ability.
Animals have instinctive communication systems.
When a dog, a puppy gets to certain age, it's able to bark.
It barks without having to learn how from other dogs, it just barks.
But much of human language has to be learned from other humans.
What else makes human language unique?
What makes it different from animal communication? Debber?
How about grammar? Like having verbs, nouns, adjectives?
OK, that's another feature. And it's a good example...
I mean I mention this cause like in my biology class last year, I kind of remember talking about a study on prairie dogs, where, I think the researchers claimed that the warning cries of prairie dogs constitute language, because they have this, different parts of speech.
You know, like nouns, to name the type of predator they spotted, adjectives to describe its size and shape, verbs..., but now it seems like...
All right, hold on a moment.
I'm familiar with the study you're talking about.
And for those of you who don't know, prairie dogs are not actually dogs.
They're type of rodent who burrow in the ground and the grasslands of the west United States and Mexico.
In this study, the researchers looked the high-pitched barks a prairie dog makes when it spots predator.
And from this they made some pretty... well, they made some claims about these calls qualifying as an actual language, with its own primitive grammar.
But actually, these warning calls are no different from those found among certain types of monkeys.
Well, let's not even get into the question whether concepts like noun and verb can be meaningfully applied to animal communication.
Another thing that distinguishes a real language is a property we call ""discreteness"".
In other words, messages are built up out of smaller parts, sentences out of words, words out of individual sounds, etc.
Now maybe you could say that the prairie dog's message is built from smaller parts, like say for example, our prairie dogs spot a predator, a big coyote approaching rapidly.
So the prairie dog makes a call that means ""coyote"", then one that means ""large"", and then another one to indicate ""speed"".
But you really suppose it makes any difference what order these calls come in?
No. But the discrete units that make up language can be put together in different ways.
Those smaller parts can be used to form an infinite number of messages, including messages that are completely novel, that have never been expressed before.
For example, we can differentiate between: ""A large coyote moves fast."" and say ""Move the large coyote fast."" or ""Move fast, large coyote."", and I truly doubt whether anyone has ever uttered either of these sentences before.
Human language is productive and open-ended communication system, whereas no other communication system has this property.
And another feature of language that's not displayed by any form of animal communication is what we call ""displacement"".
That is, language is abstract enough that we can talk about things that aren't present here and now.
Things like ""My friend Jo is not in the room."" or ""It will probably rain next Thursday.""
Prairie dogs may be able to tell you about a hawk that's circling over head right now, but they never show any inclination to describe the one they saw last week. "
L10C1
"Listen to a conversation between a student and her Photography professor.Professor Johnson, there's something that's been on my mind.
Ok.
Remember last week you told us that it's really important to get our photography into a show, basically as soon as we can?
Yeap, it's a big step, no question.
Thing is, I'm sitting here and I'm just not sure how I get there.
I mean I've got some work I like, but, is it really what the gallery is looking for?
How would I know? How do I make the right contacts to get into a show. I just really don't...
Okay, hold on. Slow down.
Um, these are questions that, well, just about every young artist has to struggle with.
Ok, the first thing you should do is you absolutely have to stay true to your artistic vision.
Take the pictures you want to take.
Don't start trying to catch the flavor of the month and be trendy because you think you'll get into a show.
That never works, because you wind up creating something you don't really believe in.
It sounds uninspired, and won't make any shows.
I've seen that happened so many times.
This doesn't mean that you should go into a cave, keep up with trends.
Even think about how your work might fit in with them, but don't mindlessly follow them.
Well, yeah, I can see that.
I think though I've always been able to stay pretty true to what I want to create, not was others want me to create.
I think that comes through my work.
Ok. Just remember that is one thing to create works that you really want to create when it’s in the classroom.
The only thing at stake is your grade. But, work created outside of the classroom?
That can be a different story.
I' m not talking about techniques or things like that.
It's just there's so much more at stake.
When you're out there making art for a living, there's a lot of pressure to become something you are not and people often surrender to that pressure.
But to get stuff exhibited.
Well, you need to be a bit of an opportunist.
Here's common sense, things like ,always having a sample of your work on hand to give to people.
You won't believe that kind of contacts are opportunities you can get in this way.
And try to get your work seen in places like restaurants, book stores.
You'd be surprised how word gets around about photography in places like that.
Ok, it's just so hard to think about all those practical things and make good work, you know. "
L10L1
"Listen to part of a lecture in a Marine Biology Class.We know whales are mammals and that they evolved from land creatures.
So the mystery is figuring out how they became ocean dwellers.
Because until recently there was no fossil record of what we call ""the missing link"", that is evidence of species that show the transition between land-dwelling mammals and today's whales.
Fortunately, some recent fossil discoveries have made the picture a little bit clearer.
For example, a few years back in Pakistan, they found a skull of a wolf-like creature.
It's about fifty million years old.
Scientists had seen this wolf-like creature before, but this skull was different.
The ear area of the skull had characteristics seen only in aquatic mammals, specifically whales.
Err, well, then also in Pakistan they found a fossil of another creature, which we call Ambulocetus natans.
That's a mouthful,eh?
The name Ambulocetus natans comes from Latin of course, and means ""walking whale that swims"".
It clearly had four limbs that could have been used for walking.
It also had a long thin tail, typical of mammals, something we don't see in today's whales.
But it also had a long skeletal structure, and that long skeletal structure suggests that it was aquatic.
And very recently, in Egypt, they found skeleton of Basilosaurus.
Basilosaurus was a creature that we've already known about for over a hundred years.
And it has been linked to modern whales because of its long whale-like body.
But this new fossil find showed a full set of leg bones, something we didn't have before.
The legs were too small to be useful.
They weren't even connected to its pelvis and couldn't have supported its weight.
But it clearly shows Basilosaurus’s evolution from land creatures.
So that's a giant step in the right direction.
Even better, it establishes Ambulocetus as a clear link between the wolf-like creature and Basilosaurus.
Now these discoveries don't completely solve the mystery.
I mean, Ambulocetus is a mammal that shows a sort of bridge between walking on land and swimming.
But it also is very different from the whales we know today.
So, really we are working with just a few pieces of a big puzzle.
Emm, a related debate involved some recent DNA studies.
Remember, DNA is the genetic code for any organism, and when the DNA from two different species is similar, it suggests that those two species are related.
And when we compared some whale's DNA with DNA from some other species, we got quite a surprise.
The DNA suggests that whales are descendants of the hippopotamus.
Yes the hippopotamus! Well, that came as a bit of shock.
I mean that a four-legged land and river dweller could be the evolutionary source of a completely aquatic creature up to twenty five times its size.
Unfortunately, this revelation about the hippopotamus apparently contradicts the fossil record, which suggests that the hippopotamus is only a very distant relative of the whale, not an ancestor.
And of course as I mentioned that the whales are descendant not from hippos but from that distant wolf-like creature.
So we have contradictory evidence.
And more research might just raise more questions and create more controversies.
At any rate, we have a choice.
We can believe the molecular data, the DNA, or we can believe the skeleton trail.
But unfortunately, probably not both.
Um, and there have been some other interesting findings from DNA research.
For a long time, we assumed that all whales that had teeth, including sperm whales and killer whales were closely related to one another, and the same for the toothless whales, like the bule whale and other baleen whales.
We assumed that they be closely related.
But recent DNA studies suggest that's not the case at all.
The sperm whale is actually closely related to the baleen whale, and it's only distantly related to the toothed-whales.
So that was the real surprise to all of us. "
L10L2
"Listen to part of a lecture in a European History Class.So would it surprise you to learn that many of the food that we eat today consider traditional European dishes that their key ingredients were not even known in Europe until quite recently, until the European started trading with the native people in North and South America?
I mean, you probably aware that the Americas provide Europe and Asia with foods like squash, beans, turkey, peanuts.
But what about all those Italian tomato sauces, hungarian goulashor my favorite, French fries? Those yummy fried potatoes.
Wait. I mean I knew potatoes were from where, South America?
South America. Right, the Andes Mountains.
But you are saying tomatoes too?
I just assume since they're used in so many Italian dishes.
No, like potatoes, tomatoes grew wild in the Andes.
Although unlike potatoes, they weren't originally cultivated there.
That seems to have occurred first in Central America.
And even then the tomato doesn't appear to have been very important as a food plant until the Europeans came on the scene.
They took it back to Europe with them around 1550.
And Italy was indeed the first place where it was widely grown as food crop.
So in a sense, it really is more Italian than American.
And another thing and this is true of both potato and tomato.
Both of these plants are members of Nightshade family.
The Nightshade family is a category of plants which also includes many that you wouldn't want to eat, like mandrake, belladonna, and even tobacco.
So it's no wonder that people once considered tomatoes and potatoes to be inedible too, even poisonous.
And in fact, the leaves of the potato plant are quite toxic.
So it took both plants quite a while to catch on in Europe.
And even longer before it made a return trip to North America and became popular food items here.
Yeah, you know, I remember, I remember my grandmother telling me that when her mother was a little girl, a lot of people still thought tomatoes are poisonous.
Oh, sure. People didn't really start eating them here until the mid-eighteen hundreds.
But seems like I heard didn't Tom Jefferson grow them or something?
Well, that's true.
But then Jefferson is known not only as the third president of the United States, but also as a scholar who was way ahead of his time in many ways.
He didn't let the conventional thinking of his day restrain his ideas.
Now, potatoes went through a similar sort of rejection process, especially when they were first introduced in Europe.
You know how potatoes can turn green if they are left in the light too long?
And that greenish skin can make the potatoes taste bitter; even make you ill.
So that was enough to put people off for over 200 years. Yes, Bill?
I'm sorry professor Jones. But I mean yeah ok.
American crops have probably contributed a lot to European cooking over the years. But...
But have they really played any kind of important role in European history?
Well, as a matter of fact, yes. I was just coming to that.
Let's start with North American corn or maize, as it's often called.
Now before the Europeans made contact with the Americas, they subsist mainly on grains, grains that often suffered from crop failures.
And it's largely for this reason that the political power in Europe was centered for centuries in the South, around the Mediterranean Sea which was where they could grow these grains with more reliability.
But when corn came to Europe from Mexico, wow, now they had a much hardier crop that could be grown easily in more northerly climates and centers of power began to shift accordingly.
And then, well, as I said potatoes weren't really popular at first.
But when they finally did catch on which they did first in Ireland around 1780.
Well, why do you suppose it happen?
Because potatoes have the ability to provide an abundant and extremely nutritious food crop, no other crop grown in North Europe at the time had anything like the number of vitamins contained in potatoes.
Plus, potatoes grow on the single acre of land could feed many more people than say, uh....wheat grow on the same land.
Potatoes soon spread to France and other Northern European countries.
And as a result, the nutrition of the general population improved tremendously and population soared in the early 1800 and so the shift of power from southern to northern Europe continued. "
L10C2
"Listen to a conversation between a student and an employee in the University bookstore.Hi, I bought this book at the beginning of the semester, but, something's come up and... I'd like to return it.
Well, for a full refund, store policy is that you have to return merchandise 2 weeks from the time it was purchased, er... but for science text books or anything having to do with specific courses.
Wait... was it for specific course?
Yeah, but actually...
Well... for course books, the deadline is 4 weeks after the beginning of the semester.
So for this fall semester, the deadline was October 1st.
Ouch, then I missed it. But, why October 1st?
Well, I guess the reasoning is that by October 1st, the semester is in full gear.
And everyone kind knows what courses they’ll be taking that semester
I get it.so it's mainly for people who decide to withdraw from… or to change to new courses early on.
Exactly! The books have to be in perfect condition of course.
They can't be marked up or looked used in any way for the full refund, I mean.
Well, but, my situation is a little different. I hoped you might be able to make an exception.
Well, the policy is generally pretty rigid and the semester is almost over.
Okay, here is what happened?
Um, I think my professor really miscalculated.
Anyway the syllabus was way too ambitious in my opinion.
There're only 2 weeks of classes left in the semester and there are like 6 books on the syllabus that we haven't even touched.
I see. So you're hoping to return in this one.
Yeah, professor already announced that we won't be reading this one by Jane Bowles and all the others I bought used.
Jane Bowles? Which book of hers?
It's called ""Two serious ladies"".
Oh, but you should keep that one. Are you interested in literature?
Well. I am in English major.
You are lucky to have professor who includes the lesser known writer like her on the syllabus, you know, not the usual authors we've all read.
So you really think...
I do. And especially if you're into literature.
Hem, well, this I wasn't expecting. I mean... er, em... Wow.
I hope you don't think I'm being too pushy.
If you prefer, you can return the book and arrange for a store credit, you don't qualify for a refund.
Policy is policy after all, but you can make an exchange and you can use the credit for your books for next semester.
The credit carries over from one semester to the next.
Hmm... that's good to know, but now I am really intrigued, I guess that just because we run out of time to read this book in class, doesn't mean that I cannot read it on my own time.
You know, I think I'll give it a try. "
L10L3
"Listen to part of a lecture in an ecology class.So we've been talking about nutrients, the elements in the enviroment that are essential for living organisms to develop, live a healthy life and reproduce.
Some nutrients are quite scarce; there just isn't much of them in the environment.
But fortunately, they get recycled.
When nutrients are used over and over in the environment, we call that a nutrient cycle.
Because of the importance of nutrients and their scarcity, nutrient recycling is one of the most significant ecosystem processes that we'll cover in this course.
The three most important nutrient cycles are the Nitrogen cycle, the Carbon cycle, and the one we are going to talk about today, the Phosphorus cycle.
So the phosphorus cycle has been studied a lot by ecologists because like I said phosphorus is an important nutrient and is not so abundant.
The largest quantities are found in rocks and at the bottom of the ocean.
How does Phosphorus get there?
Well, let's start with the Phosphorus in rocks.
The rocks gets broken down into smaller and smaller particles as they are weathered.
They are weathered slowly by rain and wind over long periods of time.
Phosphorus is slowly released as the rocks are broken down and it gets spread around into the soil.
Once it's in the soil, plants absorb it through their roots.
So that's the reason people mined rocks that contain a lot of phosphorus to help with the agriculture?
Uh-huh, they mined the rock ,artificially break it down and put the phosphorus into the agriculture fertilizers.
So humans can play a role in the first part of Phosphorus cycle----
The breaking down of rocks and spreading the Phosphorus into the soil ,by speeding up the rate at which this natural process occurs. You see.
Now after the Phosphorus is in the soil, plants grow, they use phosphorus from soil to grow; and when they die, they decompose.
And the Phosphorus is recycled back into the soil, the same thing with the animals that eat those plants, or eat other animals that have eaten those plants.
We call all of this the land phase of the Phosphorus cycle.
But a lot of the Phosphorus in the soil gets washed away into rivers by rain and melting snow; and so begins another phase of the cycle.
Can any one guess what it's called? Nancy.
Well, if the one is called the land phase, then this has to be call the water phase, right?
Yes, that's such a difficult point, isn't it?
In a normal water phase, rivers eventually empty into oceans and once in the oceans, the Phosphorus gets absorbed by water plants like algae.
Then fish eats the algae, or eat other fish that have eaten those plants.
But the water phase is sometimes effected by excessive fertilizers.
If not all of the phosphorus gets used by the crops and large amounts of phosphorus gets into the rivers, this could cause a rapid growth of water plants in the river, which can lead to the water ways getting clogged with organisms, which can change the flow of the water.
Several current studies are looking at these effects and I really do hope we can find the way to deal with this issue before these ecosystems are adversely affected. OK?
Of course, another way that humans can interrupt the normal process is fishing.
The fishing industry helps bring Phosphorus back to land.
In the normal water phase the remaining Phosphorus makes its way, settles to the bottom of the ocean and gets mixed into the ocean sediments.
But remember, this is a cycle.
The Phosphorus at the bottom of the ocean has to somehow make its way back to the surface, to complete the cycle, to begin the cycle all over again.
After millions of years, powerful geological forces like underwater volcanos lift up the ocean sediments to form new land.
When a underwater volcano pushes submerged rock to the surface, a new island is created.
Then over many more years the Phosphorus-rich rocks of the new land begin to erode, and the cycle continues.
What about, well, you said that the Nitrogen cycle is also an important nutrient cycle.
And there is a lot of nitrogen in the atmosphere, so I was wondering, is there a lot of Phosphorus in the atmosphere too?
Good question, George.
You are right to guess the Phosphorus can end up in the earth's atomosphere.
It can move from the land or from the oceans to the atomosphere and vice versa.
However there's just not substantial amount of it there, like there is with Nitrogen.
It's a very minimal quantity. "
L10L4
"Listen to a part of lecture in a psychology class.OK. If I ask about the earliest thing you can remember, I'll bet for most of you your earliest memory, would be from about age 3, right?
Well, that's true for most adults.
We can't remember anything that happened before the age of 3.
And this phenomenon is so widespread and well documented.
it has a name. It's called childhood amnesia and was first documented in 1893.
As I said, this phenomenon refers to adults not being able to remember childhood incidents.
It's not children trying to remember events from last month or last year.
Of course it follows that if you can't remember an incident as a child, you probably won't remember it as an adult.
OK, so, so why is this?
What are the reasons for childhood amnesia?
Well, once a popular explanation was that childhood memories are repressed ... uh, the memories are disturbing so as adults we keep them buried,
And so we can recall them.
And this is based on well, well, it's not based on, on, on the kind of solid research in lab testing I want to talk about today.
So let's put that explanation aside and concentrate on just two. OK?
It could be that as children we do form memories of things prior to age 3, but forget them as we grow older.
That's one explanation.
Another possibility is that children younger than 3 lack, lack some cognitive capacity for memory.
And that idea that children are unable to form memories that's been the dominant belief in psychology for the past hundred years.
And this idea is very much tied to two things.
The theories of Jean Piaget and also to language development in children.
So, Piaget's theory of cognitive development.
Piaget suggested that because they don't have language, children younger than 18 to 24 months live in the here and now, that is they lack the means to symbolically represent objects and events that are not physically presented.
Everybody get that?
Piaget proposed that young children don't have a way to represent things that aren't right in front of them.
That's what language does, right?
Words represent things, ideas.
Once language starts to develop, from about age 2, they do have a system for symbolical representation and can talk about things which aren't in their immediate environment, including the past.
Of course, he didn't claim that infants don't have any sort of memory.
It's acknowledged that they can recognize some stimuli, like faces.
And for many years, this model was very much in favor in psychology, even though memory tests were never performed on young children.
Well, finally in the 1980s, a study was done.
And this study showed that very young children under the age of 2 do have the capacity for recall.
Now, if the children can't talk, how was recall tested?
Well, that's a good question, since the capacity for recall has always been linked with the ability to talk.
So the researchers set up an experiment using imitation-based tasks.
Adults used props, uh, toys or other objects to demonstrate an action that have 2 steps.
The children were asked to imitate the steps immediately.
And then again after delays of one or more month.
And even after a delay, the children could, could recall or replicate the action, the objects used, the steps involved and the order of the steps.Even children as young as 9 month.
Now, tests showed that there was a faster rate of forgetting among the youngest children.
But most importantly, it showed that development of recall did not depend on language development.
And that was an important finding.
I guess I should add that the findings don't say that there was no conncetion, no connection between the development of language and memory.
There are some evidence that being able to talk about that event does lead to having a stronger memory of that event.
But that doesn't seem to be the real issue here.
So back to our question about the cause of childhood amnesia.
Well, there is something called the rate of forgetting and the childhood amnesia may reflect the high rate of forgetting.
In other words, children under the age of 3 do form memories and do so without language.
But they forget the memories at a fast rate, probably faster than adults do.
Researchers have set a standard, sort of unexpected rate of forgetting.
But that expected rate was set based on tests done on adults.
So what is the rate of forgetting for children under the age of 3.
We expect it to be high. But the tests to prove this really haven't been done yet. "
L11C1
"Listen to a conversation between a student and a university employee.Hi, I need to pick up the gym pass.
OK. I'll need your name, year, and university ID.
Here's my ID card. And my name is Gina Kent, and I'm first year.
OK. Gina. I'll type up the pass for you right away.
Great! This is exciting. I can't wait to get started.
Oh, this is a wonderful gym.
That's what everybody has been saying.
Everyone is talking about the new pool, the new indoor course.
But what I love is all the classes.
The classes?
Yes, like the swimming and tennis classes and everything.
Oh yeah, but this pass doesn't entitle you to those.
It doesn't?
No, the classes fall into separate category.
But, that's my whole reason for getting a pass.
I mean, I was planning to take a swimming class.
But that's not how it works.
This pass gives you access to the gym and to all the equipments, and to the pool and so forth.
But not when the teams are practicing, so you'll have to check the schedule.
But what do I have to do if I want to take a class?
You have to: one, register; and two, pay the fee for the class.
But that's not fair.
Well, I think if you can think about it.
You'll see that it's fair.
But people who play sports in the gym... they don't have to pay anything.
Yes, but they just come in, and play or swim on their own.
But, taking a class - that is a different story, I mean, someone has to pay the instructors.
So, if I want to enroll in a class.
Then you have to pay extra. The fee isn't very high, but there's a fee.
So, what class did you say you want to take?
Swimming.
OK. Swimming classes are thirty dollars a semester.
I guess I could swing that.
But I'm still not convinced it's fair.
So, do I pay you?
Well, first, you need to talk to the instructor.
They have to assess your level and steer you to the right class, you know, beginner, intermediate...
You mean, I have to swim for them? Show them what I can do?
No, no, you just tell them a little bit about your experiences and skills, so they know what level you should be in.
Oh, OK. So, I guess I'll need an appointment.
And I can make that for you right now.
And I'll type up your gym ID card. You'll need it to get into the building.
Now about that appointment... how does Wednesday at three sounds?
Fine...
OK. Then you'll be meeting with Mark Gettys.
He's the swimming instructor. He also coaches the swim team.
And here, I've jotted it all down for you.
Great! Thanks. "
L11L1
"OK, today we are going to continue our discussion of the parenting behaviors of birds.And we are going to start by talking about what are known as ""distraction displays"".
Now if you are a bird, and there was a predator around, what are you going to do?
Well, for one thing you are going to try to attract as little attention as possible, right?
Because if the predator doesn't know you are there, it's not going to try to eat you.
But sometimes certain species of birds do the exact opposite.
When the predator approaches, they do their best to attract the attention of that predator.
Now why would they do that?
Well, they do that to draw the predator away from their nests, away from their eggs or their young birds.
And the behaviours that the birds engage in to distract predators are called ""distraction displays"".
And there are a number of different kinds of distraction displays.
Most of the time, when birds are engaging in distraction displays, they are going to be pretending either that they have injury, or that they are ill, or that they are exhausted.
You know something that will make the predator think: Ah... , here is an easy meal.""
One pretty common distraction display is what's called the ""broken wing display"".
And in a broken wing display, the bird spreads and drags a wing or its tail, and while it does that, it slowly moves away from the nests, so it really looks like a bird with a broken wing.
And these ""broken-wing displays"" can be pretty convincing.
Another version of this kind of ""distraction display"" is where the birds create the impression of a mouse or some other small animals that's running around the ground.
A good example of that kind of display is created by a bird called ""the purple sandpiper"".
Now what the purple sandpiper does is when a predator approaches, it drags its wings,
but not to give it the impression that its wings is broken,
but to create the illusion that it has a second pair of legs.
And then it raises its feathers, so it looks like it's got a coat of fur.
And then it runs along the ground swirling left and right, you know like it's running around little rocks and sticks.And as it goes along it makes a little squealing noises.
So from a distance it really looks and sounds like a little animal running along the ground trying to get away.
Again, to the predator, it looks like an easy meal.
Now, what's interesting is that birds have different levels of performance of these distraction displays.They don't give their top performance, their prime time performance every time.
What they do is they save their best performances ,their most conspicuous and most risky displays for the time just before the baby birds become able to take care of themselves.
And they time it that way because that's when they'll have made the greatest investment in parenting their young.
So they are not gonna put on their best performance just after they laid their eggs, because they haven't invested that much time or energy in parenting yet.
The top performances are going to come later.
Now you have some birds that are quite mature, are quite capable, almost as soon as they hatch, and in that case, the parent will put on the most conspicuous distraction displays just before the babies' hatch.
Because once the babies are hatched, they can pretty much take care of themselves.
And then you have other birds that are helpless when they hatch.
In that case, the parent will save its best performances until just before the babies get their feathers. "
L11L2
"Listen to part of a lecture in an Architecture Class.Today, we are taking a little detour from the grand styles of public architecture we've been studying to look at residential architectures in the United States.
Since this is something we can all identify with, I think it will help us see the relationship between the function of a structure and its style or form.
This has been an ongoing theme in our discussions, and we will be getting back to it in just a moment.
But before we get started, I want you to take a moment to think: does anyone know what the single most popular style for a house in the United States is today? Bob?
I bet it is the ranch-style house.
Well, in this area, probably. But are we typical? Yes, Sue.
How about the kind of house my grandparents live in? They call it a Cape Cod.
That's the one.
Here is a drawing of what we consider of a classic Cape Cod house.
These days, you see this style all over the United States.
But it first showed up in U.S. northeast, in the New England region, around the late 1600s.
For those of you who don't know the northeast coastal region, Cape Cod is a peninsula, a narrow strip of land that jets out into the Atlantic.
And so many houses in this particular style were built on Cape Cod, that the name of the place became the name of the style.
Now why did the Cape Cod style house become so popular in the northeast?
Well, one reason is that it's a great example of form following function.
We've talked about this design principle a lot about form following function.
And what did we say it meant?
Someone give me an application of this principle.
What did this concept that form should follow function?
How would it be applied to housing design?
Well, if it means the design of the building, it should be based on the needs of people who use it.
Then, well, the architect has to be very practical to think about the people who actually be living in the house or working in the office building, whatever.
So for the architect, it's all about users not about showing off how creative you can be.
Good, of course, for a Cape Cod house, it might be even more accurate to say that form also follows climate.
Who knows what the climate's like on Cape Cod?
Cold in the winter...
And whenever I visit my grandparents, it's really wet.
It's usually either raining or snowing or foggy and windy, too.
I guess because it's so exposed to the ocean?
That's right. So take another look at this drawing, and you can imagine how this design might be particularly helpful in that kind of climate.
Notice how the house sits fairly low to the ground.
This relatively low compact structure helps the house withstand the strong winds blowing off the ocean.
And look at the slope of the roof, the steep angle helps keep off all that rain and snow that accumulates in the winter.
Another thing, Cape Cod houses usually face south to take advantage of the sun's warm through the windows.
That's helpful in winter.
Now what can you tell me about the chimney, about its location.
Well, it's in the middle. Because, does that have something to do with heating the houses?
I mean since the heat never has to travel very far.
That mean you can heat the house more efficiently, right?
Exactly, now see how the house has very little exterior decoration, that's also typical of early Cape Cod houses.
The wind was one reason, nothing sticking out that might blow away in the harsh weather, but there was probably another reason, not related to the climate, more reflection of a rural New England society back then.
You see, Cape Cod houses were not built in the big cities, where all the rich people lived back then.
These were the modest dwellings the people who built them simply couldn't afford lots of expensive decorated details.
But it was more than just matter of money.
In these rural areas, people depended on each other for survival.
Neighbors had to help and supported each other in the difficult environment, so you didn't want to appear to be showing off.
You wanted to avoid anything that might set you apart from your neighbors, the same people you might need to help you someday.
So all these help to create an attitude of conformity in the community, and you can see why a modest, a very plain style would become so widely imitated through out rural New England.
It is plain, but you know it's nice looking.
Good point, and in fact it's precisely that as aesthetic appeal, the... the purity,the nearly perfect proportions of the house... that's another reason for the Cape Cod's enduring popularity even in the places where the climate was so mild that its functional design doesn't matter. "
L11C2
"Listen to a conversation between a student and a Professor.Hi professor Atkins, you wanted to see me.
Hi Bill. Thanks for coming.
I want to talk to you about...
Is there something wrong with my research paper?
No, not at all, in fact it's very good. That's why I want to talk to you.
Oh, thanks.
I think you know that the department is looking to hire a new professor.
Are you familiar with our hiring process?
No, but what's that got to do with me?
Well, Bill, we have several qualified applicants we are serious about.
And as part of the interview process, we have to meet with a committee of professors and students in our department.
They also have to give a talk.
You mean, like a lecture?
Yes, like a sample lecture on one of their academic interests.
Oh, see you can see their teaching style.
Exactly.
Uh-huh... Make sense.
So I'd like to know if you'd be willing to join us as a student representative on the interview committee.
It'd be a good experience for you. You could put it on your resume.
Oh... that'd look good for my grad school application, I guess.
So, what do I have to do?
The department secretary will give you a schedule of the applicant's visits.
If you are free, we'd like you to attend their talks and then later you can give us your opinion.
Oh and we usually serve lunch or snacks depending on what time the talk is.
Cool, that's another good reason to do this.
Um... when is the next talk?
We actually haven't had any yet, the first one is next Friday at 10 AM, then lunch,and then the formal discussion with the applicant right after.
Oh well, I'm free on Fridays.
If all the talks are on Fridays, I will be able to make it to all of them.
That's great. Now you should know that this job candidate is interested in the life cycles in the forest.
That's what my research about.
Yes, I know, that's why I feel it's necessary to point out that even though this applicants' research interests are similar to yours, we want you to tell us what you think about the teaching of all these applicants.
Your perspective as a student. How the applicant teaches in the classroom, that's what's important to us.
I understand. So how many applicants are there?
Let's see... we have 4, all very good candidates, that we will be looking at over the next few weeks.
It's going to be a tough decision.
But it'll be a good experience for you, especially if you're going to grad school.
Thank you. It'll be cool to do this.
I'll get the copy of the schedule from the secretary on my way out.
You're welcome, see you in class this afternoon. "
L11L3
"Listen to part of a lecture in an environmental science class.When land gets developed for human use, the landscape changes.
We don't see as many types of vegetation, trees, grasses and so forth.
This in turn leads to other losses: the loss of animal that once lived there.
Err... but these are the obvious changes, but there are also less obvious changes like the climate.
One interesting case of this... of changes in the local land use causing changes in climate, specifically the temperature is in Florida.
Now what comes to mind when you think of the state of Florida?
Sunshine, beaches.
Warm weather, oranges...
Yes, exactly.
Florida has long had a great citrus industry - large growth of oranges, lemons and the like.
Florida's winter is very mild; the temperature doesn't often get below freezing.
But there are some areas of Florida do freeze.
So in the early 1900s, farmers moved even further south in Florida, to areas that were even less likely to freeze.
Obviously, freezing temperatures are a danger to the crops.
A bad bout of cold weather, a long spell of frosts could ruin a farmer's entire crop.
Anyway, before these citric growers moved south, much of the land in south Florida, was what we called wetlands.
Wetlands are areas of marshy, swampy land, areas where water covers the soil, or is present either at or near the surface of the soil for a large part of the year.
Wetlands have their own unique ecosystems, with plants and animals with special and interesting adaptations.
Very exciting, but it's not what we are talking about today.
Emm... where was I?
Farmers moved south?
Oh, yes. Farmers moved south. But the land was not suitable for farming.
You can't grow oranges in wetland, so farmers had to transform the wetlands into lands suitable for farming.
To do that, you have to drain the water from the land, move the water elsewhere, and divert the water sources such as rivers.
Hundreds of miles of drainage canals were built in the wetlands.
Now these areas, the new areas the farmers moved to, used to be warm and unlikely to freeze, however, recently the area has become susceptible to freezes.
And we are trying to understand why.
Is it some global temperature change or weather pattern like El NiNO or something?
Well, there are two theories.
One idea is as you suggested that major weather patterns, something like El NiNO, are responsible.
But the other idea and this is the one that I personally subscribe to, is that the changes in the temperature pattern had been brought about by the loss of wetlands.
Well, how would the loss of wetlands make a difference?
Well, think about what we've been studying so far.
We discussed the impact of landscapes on temperature, right?
What affects does the body of water have on an area?
Oh, yeah. Bodies of water tend to absorb the heat during the day, and then they release the heat at night.
Yes, exactly.
What you just said is what I want you all to understand.
Bodies of water release heat and moisture back into the environment.
So places near large bodies of water are generally milder, err... slightly warmer than those without water.
And what I, another think is that the loss of the wetlands has created the situation where the local temperatures in the area are now slightly different, slightly colder than they were 100 years ago, before the wetlands were drained.
Emm... do we know what the temperature was like back then?
Well, we were able to estimate this.
We have data about South Florida's current landscape, emm... the plant cover.
And we were able to reconstruct data about its landscape prior to 1900.
Then we enter those data, information about what the landscape look like before and after the wetlands were drained.
We enter the data into a computer weather model.
This model can predict temperatures.
And when all the data were entered, an overall cooling trend was predicted by the model.
How much colder does it get now?
Well, actually the model shows a drop of only a few degrees Celsius.
But this is enough to cause dramatic damage to crops.
If temperatures overnight are already very close to the freezing point, then this drop of just a few degrees can take the temperature below freezing.
And freezing causes frosts, which kill crops.
These damaging frosts wouldn't happen if the wetlands were still in existence, just a tiny temperature difference can have major consequences. "
L11L4
"Listen to part of a lecture in a Business Class.Let's get started.
Um, last time we were talking about the need for advertising.
Now, let's look at how you can successfully call attention to the service or product you want to sell.
To succeed, you've got to develop a systematic approach.
If you don't come up with a system, um, a plan, you risk making decisions that waste money, or even drive away potential customers.
But what does a systematic advertising plan look like?
Well, it covers what we call the 'Four Ms'.
The 'Four Ms': Market, Media, Money, Message.
All are important areas to focus on when creating your advertising plan.
We will look at them one by one.
The First step is to look at your Market, that's the people who might become customers, buyers of your service or product.
You need to know all about your possible customers:
Who are they? What age group are they? What do they like, or dislike? How do they shop?
So, you got that?
A market is a group of potential customers.
Next, Media...
Obviously the major media are television, radio, newspapers, magazines, um, billboards, and so forth.
There are all avenues of communication.
And you need to figure out: Which media you should advertise through? Which media will reach your intended audience - your market?
So, you do research, trying to determine which media will reach the most potential customers for the lowest cost.
For instance, if you have a product, that ...oh....say teachers would like, then teachers are your market.
So you ask yourself: What magazines do the majority of teachers read?
What TV programs do teachers watch?
Do teachers listen to much radio?
At what times of the day?
Say, now your research turns up two magazines that teachers read.
And it also shows that the majority of teachers - say ages twenty to thirty - read the magazine about classroom activities.
While most teachers older than that read the other magazine, the one about, oh, let's say ""Educational Psychology"".
You think your product will appeal most to teachers ages twenty to thirty, so you decide to put your advertisement in their favor magazine, the one about classroom activities.
You don't waste money advertising in the ""Educational Psychology"" magazine, you know, the one that the younger teachers generally don't read.
And since you're reaching the majority of the teachers in your target age group, you're probably spending your money well, which bring us to the third M - Money.
You have an advertising budget to spend, but how do you spend it wisely.
Again, research is the key.
Good research gives you facts, facts that can help you decide, well, as we already mentioned, decide the right market to target, and the best media to use.
But also: When to advertise? Or... or how to get the best rates?
Like, may be you're advertising Sports equipment, and you have been spending most of your budget during the holiday season when people buy gifts for each other.
Now, in theory, that would seem a great time to advertise, but may be research shows you're wrong, that the customers who buy sports equipment tend not to give it as a holiday gift, but want to use it themselves.
In that case, advertising during a different season of the year might give you better results.
And, um, maybe at even lower, non-holiday rates, so you actually save money.
But you need to get the facts, facts that come from good research to be certain and know for sure that you're getting your money's worth.
OK, finally, there is your message: What you want to say about your product?
Why buying it will make the customer's life easier, or safer or better somehow.
Whatever the message is, make sure you get it right.
Let me give you an example of not getting it right, Ha...ha...ha... you are going to love this one: There was this Soup Shop, the soup was really tasty, but there weren't a lot of customers.
The owner thought that may be if they gave something away for free with each purchase, then more people would come buy soup.
So they got some cheap socks, and they advertised to give a pair away with each bowl of soup.
But, then even fewer people came to the restaurant.
Well, you can imagine why.
People started to associate the soup with feet.
They began to imagine the soup smelled like feet.
The advertising message, soup means free socks, was a bad choice. It was a waste of money.
And worse, it caused the loss of customers.
Now, I want everyone to get into small groups and come up with some examples, not of good advertising messages, but of truly disastrous ones.
Think of real examples or make some up, and talk about the reasons those messages are unsuccessful.
And then we'll get back together and share. "
L12C1
"Listen to a conversation between a student and a professor.So Professor Tibbits, your notes said that you want to see me about my Hemingway paper.
I have to say that grade wasn't what I was expecting.
I thought I'd done a pretty good job.
Oh, you did. But do you really want to settle for pretty good when you can do something very good?
You think it can be very good?
Absolutely!
Would that mean you'd... I could get a better grade?
Oh, sorry! It's not for your grade. It's...
I think you could learn a lot by revising it.
You mean, rewrite the whole thing? I'm really swamped.
There's deadlines wherever I turn and... and I don't really know how much time I could give it.
Well, it is a busy time, with spring break coming up next week.
It's your call. But I think with a little extra effort, you could really turn this into a fine essay.
No... yeah... I mean, after I read your comments, I... I can see how it tries to do too much.
Yeah. It's just too ambitious for the scope of the assignment.
So I should cut out the historical part?
Yes. I would just stick to the topic. Anything unrelated to the use of nature imagery has no place in the paper.
All that tangential material just distract from the main argument.
Yeah, I never know how much to include. You know... where to draw the line?
Tell me about it! All writers struggle with that one.
But it's something you can learn. That will become more clear with practice.
But I think if you just cut out the... emm...
The stuff about history, but if I cut out those sections, won't it be too short?
Well, better a short well-structured paper than a long paper that's poorly-structured and wanders off topic.
So all I have to do is to delete those sections?
Well, not so fast. After you cut out those sections, you'll have to go back and revise the rest, to see how it all fits together.
And of course, you'll have to revise the introduction too, to accurately describe what you do in the body of the paper.
But that shouldn't be too difficult.
Just remember to keep the discussion focused.
Do you think you can get it to me by noon tomorrow?
Wow... emm... I have so much.. er.. but I'll try.
OK, good! Do try!
But if you can't, well, shoot for after spring break, OK? "
L12L1
"Listen to part of a lecture in a Biology Class.As we learn more about the DNA in human cells and how it controls the growth and development of cells, then maybe we can explain a very important observation, that when we try to grow most human cells in laboratory, they seem programmed to divide only a certain number of times before they die.
Now this differs with the type of cell.
Some cells, like nerve cells, only divide seven to nine times in their total life.
Others, like skin cells, will divide many, many more times.
But finally the cells stop renewing themselves and they die.
And in the cells of the human body itself, in the cells of every organ, of almost every type of tissue in the body, the same thing will happen eventually.
OK, you know that all of persons' genetic information is contained on very long pieces of DNA called Chromosomes.
46 of them are in the human cells, that's 23 pairs of these Chromosomes of various lengths and sizes.
Now if you look at this rough drawing of one of them, one Chromosome is about to divide into two.
You see that it sort of looks like, well actually it's much more complex than this but it reminds us a couple of springs linked together ,two coiled up pieces of DNA.
And if you stretch them out you will find they contain certain genes, certain sequences of DNA that help to determine how the cells of the body will develop.
When researchers look really carefully at the DNA in Chromosomes though, they were amazed.
We all were, to find that only a fraction of it, maybe 20-30%, converts into meaningful genetic information.
It's incredible - at least it was to me.
But if you took away all the DNA that codes for genes, you still have maybe 70% of the DNA left over.
That's the so-called JUNK DNA.
Though the word junk is used sort of tongue-in-cheek.
The assumption is that even if this DNA doesn't make up any of the genes, it must serve some other purpose.
Anyway, if we examine the ends of these coils of DNA, we will find a sequence of DNA at each end of every human Chromosome, called a telomere.
Now a telomere is a highly repetitious and genetically meaningless sequence of DNA, what we were calling JUNK DNA.
But it does have an important purpose.
It is sort of like the plastic tip on each end of shoelace.
It may not help you tie your shoe but that little plastic tip keeps the rest of the shoelace, the shoe string from unraveling into weak and useless threads.
Well, the telomeres at the ends of Chromosomes seem to do about the same thing - protect the genes the genetically functional parts of the Chromosome from being damaged.
Every time the Chromosome divides, every time one cell divides into two, pieces of the ends of the Chromosome, the telomere, get broken off.
So after each division, the telomere gets shorter and one of the things that may happen after a while is that pieces of the genes themselves get broken off the Chromosomes.
So the Chromosome is now losing important genetically information and is no longer functional.
But as long as the telomeres are a certain length they keep this from happening.
So it seems that, when the, by looking at the length of the telomeres on specific Chromosomes we can actually predict pretty much how long certain cells can successfully go on dividing.
Now there are some cells just seem to keep on dividing regardless, which may not always be a good thing if it gets out of control.
But when we analyze the cells chemically we find something very interesting - a chemical in them, and an enzyme called telomerase.
As bits of the telomere break off from the end of Chromosome, this chemical, this telomeres can rebuild it, can help reassemble the protective DNA, the telomere that the Chromosome is lost.
Someday we may be able to take any cell and keep it alive functioning and reproducing itself essentially forever through the use of telomerase.
And in the future we may have virtually immortal nerve cells and immortal skin cells of whatever because of these chemical - telomerase can keep the telomeres on the ends of Chromosomes from getting any shorter. "
L12L2
"Listen to part of a lecture in a Business Class.Ok, as we've talked about a key aspect of running a successful business is knowing, um, getting a good sense of what the customer actually wants, and how they perceive your product.
So with that in mind, I want to describe a very simple method of researching customer preference, and it is becoming increasingly common, it's called MBWA which stands for managing by wandering around.
Now, MBWA, that's not the most technical sounding name you've ever heard, but it describes the process pretty accurately.
Here is how it works.
Basically, um, the idea is that business owners or business managers just go out and actually talk to their customers, and learn more about how well the business is serving their needs, and try to see what the customer experiences.
Because that's a great way to discover for yourself, how your product is perceived, what the strengths and weaknesses are, you know, how you can improved it that sort of thing, you know Dortans, they make soup and canned vegetables and such.
Well, the head of the company, had Dortans' topped executives walk around supermarkets, um, asking shoppers what they thought of Dortans' soups, and he use the data to make changes to the company's product.
I mean, when Dortans of all the companies, embraces something as radical as MBWA, it really show you how popular the theory has become, yes, Lisa?
But isn't it dangerous to base decisions on information from a small sample of people?
Isn't it large scale market research safer getting data on a lot of people?
That's a good question, and well I don't want to pretend that W... MBWA is some sort of, um, replacement for other methods of customer research.
Now, the market research data definitely can give you a good idea of, um, of the big picture, but MBWA is really useful kind of filling in the blanks, you know, getting a good underground sense of how you products you used, and how people need respond to them, and Yes, the numbers of opinion you get is small so you do need to be careful.
But, good business managers will tell you that the biggest fear they have and... and one of the most frequent problems they come across is, well, becoming out of touch with what their customers really want and need.
You know surveys and market research stuff like that, they can only tell you so much about what the customers actually want in their day-to-day lives.
Managing by wandering around on the other hand, that get you in there give you a good sense about what customers need.
So when use combination then, MBWA and market research were the powerful tools.
Oh, here is another example for you, um, senior executives for a clothing manufacturer.
It was, um, Lken, Lken jeans you know, they went and worked in a store for a few days, selling Lken's clothes.
Now that gave them a very different idea about their product, they saw how people responded to it.
They could go up to customers in the store and ask them questions about it, uh,yes Mike?
Well, I would think that a lot of customers will be bothered by, you know, if I'm shopping, I don't know if I'd want some business representatives coming up to me and asking me questions, it's..
It's like when I get phone calls at home from marketing researchers, I just hang up on them.
Oh, well, it's certainly true that well no one likes getting calls at home from market researchers or people like that, but I will tell you something.
Most customers have exact opposite reaction when they comes to MBWA.
Now, don't ask me why, because I really have no idea, but the fact is that customers tend to respond really well to MBWA, which is the key reason for a success.
In fact, the techniques of MBWA work so well, they have actually been extended to all kinds of different contexts ,like politics for instance.
Um, a few years back, the mayor of Baltimore, Um... I think his name was Shapher or something like that.
Anyway, he decided that the best way to serve the people of the city, of his city, was to actually get out there in it and experience the things that they experienced.
So he ride around the city in, you know, in all parts of it, and he see all the potholes; he see how the trash was sometimes, um, not pickup but off side the street and then he go back to the office and they write these memos.
Now they were memos to his staff about the problems he had seen, and how they needed to be fixed, you know that sort of thing.
But the thing is he got all the information just by going around and seeing the different Botamore neighborhoods and talking to the people in them.
And he called it smart politics, we'd call it MBWA, or just, playing good customer service. "
L12C2
"Listen to a conversation between a student and a Department Secretary.Hi. Miss Hendrix.
Hi Bret, how are you?
I'm fine, except I have a question about my paycheck.
Sure. What's up?
Well it's already been several weeks into the semester and my paycheck was supposed to go directly into my bank account but there haven't been any deposits.
That's odd.
Yeah, I thought graduate teaching assistants will automatically put on the payroll at the beginning of the semester.
They are. Let's see did you complete all the forms for payroll?
I filled in whatever they sent me, and I returned... like... at the end of August.
Hum, well, you definitely should have been paid by now.
At least two pay periods have passed since then.
I asked the bank and they didn't know anything.
Who should I talk to about this, payroll?
I'm going to contact them for you.
There was a problem in processing some of the graduate students' payroll paper work.
Cause their computer program crashed after all the information was processed.
And some people's information couldn't be retrieved.
Hum. But why didn't anyone let me know?
I don't know how they work over there, cause they couldn't even figure out whose information was missing.
And this isn't the first time, seems like something like this happens every semester.
So how do I find out if my information was lost?
I will contact them tomorrow morning to see if you're in the system.
But you're probably not.
Well, then,what will i need to do?
Sorry but you will need to fill out those forms again and then I will fax them over the payroll office.
And then what... Well, what I really need to know is how long till I get some money. I'm already a month behind on my bills and my tuition's due soon.
They'll get you into the system the same day they receive your paperwork.
So if you do that tomorrow, you'll get paid next Friday.
That's a long time from now.
Will that paycheck include all the money I am owed?
It should. I will double check with the payroll department.
And another thing, Is there any way I could get paid sooner, I have been teaching all these weeks...
I know it's not fair but I don't think they can do anything. all the checks are computed automatically in the system.
They can't just write checks.
But they are the ones that made a mistake.
And they never told me!
I understand how you feel . If I were you, I'd be upset too.
I'll tell you what:when I call them, I will explain the situation and ask if there is any way you can be paid sooner.
But I have to tell you that based on past experiences you shouldn't count on it.
I understand. Thanks. I know it's not your fault and you're doing everything you can.
Well, what I CAN do is make sure that your first check for the total amount the university owes you.
That'll be great!
Thank you. I will be on campus about 10 tomorrow morning and I will come by to see you then. "
L12L3
"Listen to part of a lecture in a music history class.The professor has been discussing Opera.
The word opera means work, actually it means works.
It's the plural of the word""opus""from the Latin.
And in Italian it refers in general to works of art.
Opera Lyric or Lyric opera refers to what we think of as opera, the musical drama.
Opera was commonplace in Italy for almost thousands of years before it became commercial as a venture.
And during those years, several things happened - primarily linguistic or thematic and both involving secularization.
Musical drama started in the churches. It was an educational tool.
It was used primarily as a vehicle for teaching religion and was generally presented in Latin, the language of the Christian Church which had considerable influence in Italy at that time.
But the language of everyday life was evolving in Europe and at a certain point in the middle ages it was really only merchants, aristocrats and clergy who can deal with Latin.
The vast majority of the population used their own regional vernacular in all aspects of their lives.
And so in what is now Italy, operas quit being presented in Latin and started being presented in Italian.
And once that happened, the themes of the opera presentations also started to change.
And musical drama moved from the church to the plaza right outside the church.
And the themes again, the themes changed.
And opera was no longer about teaching religion as it was about satire and about expressing the ideas of society or government without committing yourself to writing and risking imprisonment or persecution, or what have you.
Opera, as we think of it, is of course a resurrected form.
It is the melodious drama of ancient Greek theater, the term ""melodious drama"" being shortened eventually to ""melodrama"" because operas frequently are melodramatic, not to say unrealistic.
And the group that put the first operas together that we have today then,were, well... it was a group of men that included Galileo's father Vincenzo, and they met in Florence he and a group of friends of the Count of Bardi and they formed what is called the Giovanni de' Bardi.
And they took classical theater and reproduced it in the Renaissance time.
This... uh... this produced some of the operas that we have today.
Now what happened in the following centuries is very simple.
Opera originated in Italy but was not confined to Italy any more than Italians were.
And so as the Italians migrated to across Europe, they carried theater with them and opera specifically because it was an Italian form.
What happened is that the major divide in opera that endures today took place.
The French said opera ought to reflect the rhythm and cadence of dramatic literature, bearing in mind that we are talking about the golden age in French literature.
And so the music was secondary, if you will, to the dramatic cadence of language, to the way the rhythm of language was used to express feeling and used to add drama and of course as a result instead of arias or solos, which would come to dominate Italian opera.
The French relied on what is the Italian called rechitative or recitative in English.
The lyrics were spoken, frequently to the accompaniment of a harpsichord.
The French said you really can't talk about real people who lived in opera and they relied on mythology to give them their characters and their plots, mythology, the pastoral traditions, the novels of chivalry or the epics of chivalry out of the middle Ages.
The Italian said, no this is a great historical tool and what a better way to educate the public about Neo or Attalla or any number of people than to put them into a play they can see and listen to.
The English appropriated opera after the French.
Opera came late to England because all theaters, public theaters were closed, of course, during their civil war.
And it wasn't until the restoration in 1660 that public theaters again opened and opera took off.
The English made a major adjustment to opera and exported what they had done to opera back to Italy.
So that you have this circle of musical influences - the Italians invented opera, the French adapted it, the English adopted it, and the Italians took it back.
It came to America late and was considered to elitist for the general public.
But Broadway musicals fulfilled a similar function for a great long while.
George Champon wrote about opera, quote""If an extraterrestrial being were to appear before us and say, what is your society like, what is this Earth thing all about, you could do worse than take that creature to an opera."" End quote.
Because opera does, after all, begin with a man and a woman and any emotion. "
L12L4
"Listen to part of a lecture in an environmental science class.All right folks, let's continue our discussion of alternative energy sources and move on to what's probably the most well-known alternative energy source - solar energy.
The sun basically provides earth with a virtually unlimited source of energy every day, but the problem has always been how do we tap this source of energy.
Can anyone think of why it's so difficult to make use of solar energy?
Because it's hard to... um... gather it?
That's exactly it.
Solar energy is everywhere, but it's also quite diffused.
And the thing is the dream of solar energy is not a new one.
Humanity has been trying to use the sun's light as a reliable source of energy for centuries.
And around the beginning of the 20th century there were actually some primitive solar water heaters on the consumer market.
But they didn't sell very well.
Any of you wanna guess why?
Well, there were other energy choices like oil and natural gas, right?
Yeah, and for better or for worse, we chose to go down that path as a society.
When you consider economic factors, it's easy to see why.
But then in the 1970s, there was an interest in solar energy again.
Why do you think that happened?
Because oil and natural gas were... err... became scarce?
Well, not exactly.
The amount of oil and natural gas in the earth was still plentiful, but there were other reasons.
It's a political thing really and I'm gonna get into that now.
So what happened in the 1970s was oil and natural gas became very expensive very quickly.
And that spurred people to start looking into alternative forms of energy - solar energy probably being the most popular.
But then in the 80s, this trend reversed itself when the price of oil and natural gas went down.
All right. Let's shift our focus now to some of the technologies that have been invented to overcome the problem of gathering diffused solar energy.
The most basic solution is simply to carefully place windows in a building, so that the sun shines into the building and then it's absorbed and converted into heat.
Can anyone think of where this is most commonly used?
Greenhouses.
Yep, greenhouses, where plants are kept warm and provided with sunlight because the walls of the building are made entirely of glass.
But we do also have more complex systems that are used for space heating and they fall into two categories: passive and active heating systems.
Passive systems take advantage of the location or design of a house.
For example, solar energy is gathered through large glass panels facing the sun.
The heat is then stored in water-filled tanks or concrete.
No mechanical devices are used in passive heating systems.
They operate with little or no mechanical assistance.
With active systems, on the other hand, you collect the solar energy at one location, and then you use pumps and fans to move heat from the collectors through a plumbing system to a tank, where it can be used to heat a home or to just provide hot water.
Excuse me professor, but I've got to ask. How can solar energy work at night or on cloudy days?
That's... well... that is a really good question.
As a matter of fact, science is still working on it, trying to find ways of enhancing energy storage techniques so that the coming of night or cloudy days really wouldn't matter.
That is the biggest drawback to solar energy - the problem of what do you do in cases where the sun's light is weak or virtually non-present.
So the storage of solar energy, lots of solar energy, is a really important aspect.
Does that mean that solar energy can only be used on a small scale, like heating a home?
Well actually, there have been some attempts to build solar energy power plants.
The world's largest solar power plant is located in Kramer Junction California.
It can generate 194 megawatts of electric power, but that's just a drop in the bucket.
Right now the utility companies are interested in increasing the capacity of the Kramer Junction Plant.
But only time will tell if it will ever develop into a major source of power for that region, considering the economic and political factors involved. "
L13C1
"listen to a conversation between a student and his psychology professorGood afternoon, Alex, can I help you with something?
Well, I want to talk with you about the research project you assigned today.
I um... I hope you could clarify a few things for me.
I'll certainly try.
Ok, all we have to do is do two observations and take notes on them, right?
Er, that's a start, but you need to do some research, too.
Then you will write a paper that is not so much about the observations, but a synthesis of what you have observed and read.
Ok. And what about the children I am supposed to observe?
Not children, a single child observed twice.
Oh... ok, so I should choose a child with a permission of a child's parent of course and then observe that child a couple of times and take good notes, then?
Actually after your first observation, you go back and look through your textbook or go to a library and find a few sources concerning the stage of development, this particular child is in.
Then, with that knowledge, you will make the second observation of the same child to see if these expected developmental behaviors are exhibited.
Can you give me an example?
Well, um, if you observed a 4 year-old child, for example, my daughter is 4 years old; you might read up on Piaget's stages of cognitive development we covered those in class.
Uh-huh...
Uh, most likely, what stage would a child of that age be in?
Um... the pre-operational stage?
Exactly, if that's the case, her languages use would be maturing and her memory and imagination would be developed.
So she might play pretend like she can pretend when driving her toy car across a couch that the couch is actually a bridge or something.
That is right. In addition, her thinking would be primarily egocentric.
So she would be thinking mostly about herself and her own needs, and might not be able to see things from anyone else's perspective.
En hums...
But what if she doesn't?
I mean, what if she doesn't demonstrate those behaviors?
That's fine. You'll note that in your paper.
See, your paper should compare what is expected of children at certain stages of development with what you actually observed.
Ok, I have one more question now.
And what's that?
Where can I find a child to observe?
Er, I suggest you contact the education department secretary.
She has a list of contacts at various schools and with certain families who are somehow connected to the university.
Sometimes they are willing to help out students with projects like yours.
Ok, I'll stop by the education department office this afternoon.
And if you have any trouble or any more questions, feel free to come by during my office hours. "
L13L1
"Listen to part of a lecture in a city planning class.In the last 15 years or so, many American cities have had difficulty in maintaining a successful retail environment.
Business owners in the city centers or the downtown areas have experienced some financial losses, because of a steady movement of the people out of the cities and into the suburbs.
In general, downtown areas, just don't have that many residential areas, not that many people live there.
So what have city planners decided to do about it?
Well, one way they've come up with the some ways to attract more people, to shop downtown was by creating pedestrian malls.
Now, what is a pedestrian mall?
It's a pretty simple concept really, it is essentially an outdoor shopping area designed just for people on foot.
And... well, unlike many other shopping malls that are built in suburb nowadays, these pedestrian malls are typically located in the downtown area of the city.
And...oh... there are features like wide sidewalks, comfortable outdoor seating and maybe even fountains and, you know, art.
There are variations on this model of course, but the common denominator is always the idea of creating a shopping space that will get people to shop in the city without needing their cars.
So I am sure you can see how having an area that's off-limits to automobile traffic would be ideal for heavily populated city where, well, the streets would otherwise be bustling with noisy, unpleasant traffic congestion.
Now the concept which originated in Europe was adopted by American city planners in the late 1950s.
And since then, a number of Unites States' cities have created the pedestrian malls.
And many of them have been highly successful.
So what have city planners learned about making these malls succeed?
Well, there are two critical factors to consider when creating a pedestrian mall: location and design.
both of which are equally important.
Now let's start with location.
In choosing a specific location for pedestrian mall, there are in fact two considerations.
Proximity to potential customers, um... that's we'd call a customer base, and accessibility to public transportation which we will get to in just a moment.
Now, for a customer base, the most obvious example would be a large office building since the employees could theoretically go shopping after work or during their lunch hour, right?
Another really good example is convention center which typically has a hotel and large meeting spaces to draw visitors to the city for major business conferences and events.
But ideally, the pedestrian malls would be used by local residents, not just people working in the city or visiting the area.
So that's where access to the public transportation comes in, either... either the designers plan to locate the mall near a central transportation hub, like bus terminal, a major train, subway station, or they work with city officials to create sufficient parking areas, not too far from the mall, which make sense because people can drive into the mall area ,well, then they need to have easy access to it.
OK, so that's location, but what about design?
Well, design doesn't necessarily include things like sculptures or decorative walkways or even eye catching window displays, you know art.
Although I'd be the first to admit those things are aesthetically appealing, however, visually pleasing sights, while they are not a part of pedestrian mall design that matter the most.
The key consideration is a compact and convenient layout.
One which allows pedestrians to walk from one end of the mall to the other in just a few minutes, so they can get to the major stores, restaurants and other central places without having to take more than one or two turns.
Now, this takes careful and creative planning.
But now what if one ingredient to this planning recipe is missing?
There could quite possibly be long-lasting effects.
And I think a good example is the pedestrian mall in the Louisville Kentucky for instance.
Now when the Louisville mall was built,oh, it had lots of visual appeal. It was attractively designed, right in the small part of downtown and it pretty much possessed all of the other design elements for success.
But... now here is where my point about location comes into play.
There wasn't a convention center around to...to help draw in visitors and, well, the only nearby hotel eventually closed down for that same reason.
Well, you can imagine how this must have affected local and pedestrian mall business owners.
sort of what we call a chain reaction.
It wasn't until a convention center and a parking garage were built about decade later that mall started to be successful. "
L13L2
"Listen to a part of a lecture in an ecology class.So, continuing our discussion of ecological systems whole systems.
The main thing to keep in mind here is the interrelationships.
The species in the system and even the landscape itself, they are interdependent.
Let's take what you've read for this weekend and see if we can apply this interdependence idea. Mike?
Well, um... how about beavers, ecosystems with beavers in waterways.
Good, good, go on.
Like, well, you can see how it's so important, cause if you go back before European settled in North America, like before the 1600s, back when native Americans were the only people living here, well, back then there were a lot of beavers, but later on, after Europeans...
OK, wait, I see where you are heading with this, but before we go into how European settlement affected the ecosystem, tell me this--what kind of environment do beavers live in?
Think about what it was like before the Europeans settlers came, we'll come back to where you were headed.
OK, well, beavers live near streams and rivers and they block up the streams and rivers with like logs and sticks and mud.
You know, they build dams that really slow down the flow of the stream.
So then the water backs up, and creates like a pond that floods the nearby land.
And that creates wetlands.
OK, tell me more.
Well with wetlands, it's like there is more standing water, more still water around, and that water is a lot cleaner than swiftly flowing water, because the dirt and settlement and stuff has the chance to sink to the bottom.
More important for our discussion, wetland areas support a lot more varieties of life than swiftly flowing water.
For example, there are more varieties of fish or insects, lots of frog species, and then species that rely on those species start to live near the wetlands too.
Yes, like birds and mammals that eat the fish and insects, and you can get trees and plants that begin to grow near the standing water, that can't grow near the running water.
Oh, and there's something about wetland, and groundwater too.
OK, good.
Wetlands have a big effect on ground water, the amount of water below the surface of the land.
Think of wetlands as, umm, like a giant sponge, the earth soaks up a lot of this water that's continually flooding the surface, which increases the amount of water below.
So where is there a wetland, you get a lot of ground water, and ground water happens to be a big source of our own drinking water today.
Alright... so, back to the beavers, what if the beavers weren't there?
You just have a regular running stream, because there is no dam, so the ecosystem would be completely different, there would be fewer wetlands.
Exactly, so, now let's go back to where you were headed before, Mike.
You mentioned the change that occurred after Europeans came to North America.
Yeah, well, there used to be beavers all over the place, something like 200 million beavers, just in the continental United States.
But when Europeans came, they started hunting the beavers for their fur, because beaver fur is really warm, and it was really popular for making hats in Europe.
So the beavers were hunted a lot, overhunted.
They are almost extinct by the 1800s, so... that meant fewer wetlands, less standing water.
And what does that mean for the ecosystem? Kate?
Well if there is less standing water, then the ecosystem can't support as many species, because a lot of insects and fish and frogs can't live in running water, and then the birds and animals that eat them, lose their foods supply.
Precisely, so the beaver in this ecosystem is what we call a keystone species.
The term keystone kind of explains itself.
In architecture, a keystone in an archway or doorway is the stone that holds the whole thing together, and keeps it from collapsing.
Well, that's what a keystone species does in an ecosystem.
It's the crucial species that keeps the system going.
Now, beaver populations are on the rise again, but there is something to think about.
Consider humans as part of these ecosystems, you've probably heard about water shortages or restrictions on how much water you can use, especially in the summer time, in recent years.
And remember what I said about groundwater.
Imagine if we still have all those beavers around, all those wetlands, what would our water supply be like then? "
L13C2
"Listen to a conversation between a student and the language lab manager.Hi, I'm not sure, but err... is this the Carter language lab?
Yes, it is. How can I help you?
I'm taking the first year Spanish this semester.
Our professor says that we need to come here to view a series of videos.
I think it is called Spanish-Working on Your Accent.
Yes, we have that.
Err... They are on the wall behind you.
So, I can just take... err... can I take the whole series home?
I think there are three of them.
I guess you haven't been here before.
No, no I haven't.
Ok, well, you have to watch the videos here.
You need to sign in to reserve an open room and sign out the video you need, just start with the first one in the series, each video is half an hour long.
So, it is a video library, basically?
Yes, but unlike the library, you can't take any videos out of the lab.
OK, so how long can I use a video room for?
You can sign up for two hours at a time.
Oh, good, so I can watch more than one video when I come up here.
Is the lab pretty busy all the time?
Well, rooms are usually full right after dinner time, but you can sign up the day before to reserve the room if you want.
Err... the day before....
But, I can just stop in to see if there's any rooms open, right?
Sure, stop in any time.
What about copies of the videos? Is there just one copy of each in the series?
I don't want to miss out if everyone comes in advance.
Oh, no, we have several copies of each tape in the Spanish accent series.
We usually have multiple copies of everything for each video collection.
Super. So... how many rooms are there total in the lab?
20. They are pretty small.
So, we normally get one person or no more than a small group of people in their watching the video together.
Actually, someone else from your class just came in and took the first Spanish video in to watch.
You could probably run in there and watch it with them.
Of course, you are welcome to have own room.
But, sometimes students like to watch with classmate, so they can review the material with each other afterwards.
For example, if there was some content they didn't really understand.
I guess I prefer my own room.
I concentrate better by myself and I don't want to miss anything, you know, and he is probably already started watching it...
No problem, we've got a lot of rooms open right now.
When you come in, you sign your name on the list and you're assigned a room number ,or if you call in advance, then the attendant will tell you your room number, if you forget, just come in and take a look at the list.
The videos are over there.
Great, thanks. "
L13L3
"Listen to part of a lecture in a poetry class, the professor is discussing medieval poetry.OK, so the two poems we are looking at today fall into the category of medieval times, which was how long ago?
Almost a thousand years ago, right?
Yes, that's right.
But, professor, are you sure these are poems?
I mean I thought poems were shorter; these were more like long stories.
I mean one of them must all about love, but the other one the Chan... Chan... whatever it's called, the other one, it's all about fighting and battles.
I mean can both of them be considered to be poems?
Well, think back to the very beginning of this course.
Aha.
Remember how we, we define poetry?
In the very broadest sense, we said it's written to evoke, to make you, the audience, have some kind of the emotional experience through the use of imagery, um, some kind of predictable rhythm.
And usually, but not always, there's more than one meaning implied with the words that are used.
Let's start with the Chanson poetry first.
That's Chanson.
Chanson poems became popular in Europe, particularly in France, and the term is actually short for a longer French phrase that translates to a... huh... songs of deeds.
Now they were called songs of deeds because strangely enough, they were written to describe the heroic deeds or actions of warriors, the knights during conflicts.
We don't know a lot about the authors, it's still contested somewhat.
But we are pretty sure about who the Chanson poems were written for.
That is, they were written for the knights and the lords - the nobility that they served.
The poems were sung, performed by a minstrel, a singer who travelled from castle to castle, singing to the local lord and its knights.
Ah... well, would someone summarize the main features of the Chanson poem you read?
Well, there's a hero, and a knight, who goes to battle, and he is admired for his courage, bravery and loyalty, loyalty to the lord he serves, his country and his fellow warriors in the field.
He's a... he has a... he's a skilled fighter, willing to face the most extreme dangers, sacrificial, willing that sacrifice anything and everything to protect his king and country.
Ok, now ,given that the intended audiences for these poems were knights and lords.
What can we say about the purpose of Chanson poetry?
What kinds of feelings were it meant to provoke?
I guess they must been really appealing to those knights and lords who were listening to them.
Hearing the songs probably made them feel more patriotic, made them feel like it was a good noble thing to serve their countries in whatever way they could.
Good, we've got a pretty good picture of what the Chanson hero was like.
Now let's compare that to the hero in the other poem.
The other poem is an example of what's called Romance Poetry.
And the hero in the romance poem was also a knight.
But what made the knight in Romance Poetry different from the knight in Chanson poetry.
Well, first, the purpose of the hero's actions was different.
The hero in the Romance Poetry is independent, purely solitary in a way, not like the Chanson poet who was always surrounded by his fighting companions.
He doesn't engage in the conflict to protect his lord or country.
He does it for the sake of adventure, to improve himself, to show he's worthy of respect and love from his lady.
He's very conscious of the particular rules of social behavior he has to live up to somehow.
And all of those actions are for the purpose of proving that he is an upright,moral, well-mannered, well behaved individual.
You may have noticed that in Chanson poetry there isn't much about the hero's feelings.
The focus is on the actions, the deeds.
But the Romance Poetry describes a lot of the inner feelings, the motivations, psychology you could say, of the knight trying to improve himself, to better himself, so that he's worthy of the love of a woman.
What explains this difference?
Well, un,digging into the historical context tells us a lot.
Romance Poetry emerged a few generations after Chanson, and its roots were in geographical regions of France that were calmer, where conflict wasn't central to people's lives.
More peaceful times meant there was more time for education, travel, more time for reflection.
Another name for Romance Poetry that's often synonymous with it is troubadour poetry.
Troubadours were the authors of these new Romance poems.
And we know a lot more about the troubadours than we do about the Chanson authors, because they often had small biographical sketches added to their poems that gave pretty specific information about their social status, geographical location and small outline of their career.
These information wasn't particularly reliable because they were sometimes based on fictitious stories of great adventure or scraped together from parts of different poems.
But there is enough there to squeeze or infer some facts about their social class.
The political climate have settle down enough so that troubadours had the luxury of being able to spend most if not all of their time, creating, crafting or composing their love songs for their audiences.
And yes these poems were also sung. Many troubadours were able to make a living being full-time poets, which should tell you something about the value of that profession during the medieval times. "
L13L4
"Listen to part of a lecture in an astronomy class.Ok, I wanna go over the different types of meteorites, and what we have learned from them about the formation of Earth and solar system.
Uh... the thing is what's especially interesting about meteorites is that they come from interplanetary space, but they consist of the same chemical elements that are in matter originated on Earth, just in different proportions.
But that makes it easier to identify something as a meteorite, as it opposed to... to just a terrestrial rock.
So to talk about where meteorites come from?
We need to talk about comets and asteroids which basically...
They are basically made up of debris left over from the origin of the solar system four point six billion years ago.
Now I am going a bit out of border here.
I am not going to go into any depth on the comets and asteroids now.
But we will come back later and do that.
For now, I'll just cover some basic info about them.
Ok, comets and asteroids.
It might help if you think of... remember we talked about the two classes of planets in our solar system, and how they differ in composition?
The terrestrial planets - like Mars and Earth - composed largely of rocks and metals, and the large gas giant, like Jupiter.
Well, the solar system also has two analogous classes of objects, smaller than planets, namely, asteroids and comets.
Relatively near the Sun and inner solar system, between Jupiter and Mars to be precise, we've got the asteroid belt, which contains about 90% of all asteroids orbiting the Sun.
These asteroids are... uh... like the terrestrial planets, and they are composed mostly of rocky material and metals.
Far from the Sun, in the outer solar system, beyond Jupiter's orbit, temperatures are low enough to permit ices to form out of water and... and out of gases are like methane and carbon dioxide.
Loose collections of these ices and small rocky particles form into comets.
So comets are similar in composition to the gas giants.
Both comets and asteroids are... typically are smaller than planets.
And even smaller type of the interplanetary debris is the meteoroid.
And its from meteoroids, we get meteors and meteorites.
""Roids"" are, for the most part anyway, they are just smaller bits of asteroids and comets.
When these bits enter Earth's atmosphere, well, that makes them so special that they get a special name, they are called meteors.
Most of them are very small, and they burn up soon after entering the Earth's atmosphere.
The larger ones that make it through the atmosphere, and hit the ground are called meteorites.
So meteorites are the ones that actually make it through.
Now we have been finding meteorites on Earth for thousands of years, and we've analyzed enough of them to learn a lot about their composition.
Most come from asteroids.
Though a few may have come from comets.
So essentially, they are rocks, and like rocks, they are mixtures of minerals.
They are generally classified into three broad categories: stones, stony irons and irons.
Stone meteorites, which we refer to simply as, uh, stones, are almost entirely rock material.
They actually account for almost all of the meteorite material that falls to Earth.
But even so, it's rare to ever find one, I mean, it's easier to find an iron meteorite or stony iron.
Anyone guess why?
Look at their names.
What do you think iron meteorites consist of?
Mostly iron?
Yeah, iron and some nickle, both of which are metals.
And if you are trying to find metal?
Oh, metal detectors!
Right, thank you. At least that's a part of it.
Stone meteorites, if they lie around exposed to the weather for a few years, well, they are made of rock, so they end up looking almost indistinguishable from common terrestrial rocks, ones that originated on Earth.
So it's hard to spot them by eye.
But we can use the metal detectors to help us find the others, and they are easier to spot by eye.
So most of the meteorites in collections, uh, in museums, they will be... they are iron meteorites, or the stony iron kind, even though they only make up about 5% of the meteorite material on the ground. "
L14C1
"Listen to a conversation between the student and librarian employee.Hi, I am looking for this book, the American judicial system.
And I can't seem to find it anywhere.
I need to read a chapter for my political science class.
Let me check in the computer.
Um, doesn't seem to be checked out and it's not on reserve.
You've checked the shelves I assume.
Yeah, I even checked other shelves and tables next to where the book should be.
Well, it's still here in the library. So people must be using it.
You know this seems to be a very popular book tonight.
We show six copies. None are checked out. And, yet you didn't even find one copy on the shelves.
Is it a big class?
Maybe about Seventy Five?
Well, you should ask your professor to put some of the copies on reserve.
You know about the Reserve system, right?
I know that you have to read reserve books in the library and that you have time limits.
But I didn't know that I could ask a professor to put a book on the reserve.
I mean I thought the professors make that kind of decisions at the beginning of the semester.
Oh, they can put books on reserve at anytime during the semester.
You know reserving book seems a bit unfair.
What if someone who is not in the class wants to use the book?
That's why I said some copies.
Ah, well, I'll certainly talk to my professor about it tomorrow. But what I am gonna do tonight?
I guess you could walk around the Poli-Sci (Political Science) section and look at the books waiting to be re-shelved.
There do seem to be more than normal.
We are a little short of staff right now.
Someone quit recently, so things aren't getting re-shelved as quickly as usual.
I don't think they've hired a replacement yet, so, yeah, the unshelved books can get a bit out of hand.
This may sound a bit weird.
But I've been thinking about getting a job.
Um, I've never work at the library before, but...
That's not a requirement.
The job might still be open.
At the beginning of the semester we were swamped with applications, but I guess everyone who wants the job has one by now.
What can you tell me about the job?
Well, we work between six and ten hours a week, so it's a reasonable amount.
Usually we can pick the hours we want to work.
But since you'd be starting so late in the semester, I'm not sure how that would work for you.
And, Oh, we get paid the normal university rates for student employees.
So who do I talk to?
I guess you talk to Dr. Jenkins, the head librarian.
She does the hiring. "
L14L1
"Listen to part of a lecture in a psychology class.We've said that the term ""Cognition"" refers to mental states like knowing and believing, and to mental processes that we use to arrive at those states.
So for example, reasoning is a cognitive process, so is perception.
We use information that we perceive through our senses to help us make decisions to arrive at beliefs and so on.
And then there are memory and imagination which relate to the knowledge of things that happen in the past or may happen in the future.
So perceiving, remembering, imagining are all internal mental processes that lead to knowing or believing.
Yet, each of these processes has limitations, and can lead us to hold mistaken beliefs or make false predictions.
Take memory for example, maybe you have heard of studies in which people hear a list of related words.
Ah, let's say a list of different kinds of fruit.
After hearing this list, they are presented with several additional words.
In this case, we'll say the additional words were ""blanket"" and ""cherry"".
Neither of these words was on the original list, and, well, people will claim correctly that ""blanket"" was not on the original list, they'll also claim incorrectly that the word ""cherry"" was on the list.
Most people are convinced they heard the word ""cherry"" on the original list.
Why do they make such a simple mistake?
Well, we think because the words on the list were so closely related, the brain stored only the gist of what they heard.
For example, that all the items on the list were types of the fruit.
When we tap our memory, our brains often fill in details and quite often these details are actually false.
We also see this ""fill-in"" phenomenon with perception.
Perception is the faculty that allows us to process information in the present as we take it via our senses.
Again, studies have shown that people will fill in information that they thought they perceived even when they didn't.
For example, experiments have been done where a person hears a sentence, but it is missing the word, that logically completes it.
They'll claim to hear that word even though it was never said.
So if I were to say... er... the sunrise is in the... and then fill to complete the sentence, people will often claim to have heard the word ""east"".
In cognitive psychology, we have a phrase for this kind of inaccurate ""filling in of details"",it's called: A Blind Spot.
The term originally refers to the place in our eyes where the optic nerve connects the back of the eye to the brain.
There are no photo receptors in the area where the nerve connects to the eye.
So that particular area of the eye is incapable of detecting images.
It produces ""A Blind Spot"" in our field vision.
We are unaware of it, because the brain fills in what it thinks belongs in its image, so the picture always appears complete to us.
But the term ""blind spot"" has also taken on a more general meaning, it refers to people being unaware of a bias that may affect their judgment about the subject.
And the same ""blind-spot phenomenon"" that affects memory and perception also affects imagination.
Imagination is a faculty that some people use to anticipate future events in their lives.
But the ease with which we imagine details can lead to unrealistic expectations and can bias our decisions.
So... er... Peter, suppose I ask you to image a lunch salad, no problem, right?
But I bet you imagine specific ingredients.
Did yours have tomatoes, onion, lettuce? mine did?
Our brains fill in all sorts of details that might not be part of other people's image of a salad, which could lead to disappointment for us.
If the next time we order a salad in a restaurant, we have our imagined salad in mind, that's not necessarily what we'll get on our plate.
The problem is not that we imagine things, but that we assume what we've imagined is accurate.
We should be aware that our imagination has this built-in feature, the blind spot,which makes our predictions fall short of reality. "
L14L2
"Listen to part of a lecture in a biology class.Almost all animals have some way of regulating their body temperature.
Otherwise, they wouldn't survive extreme hot or cold conditions.
Sweating, panting, swimming to cooler or warmer water, ducking into somewhere cool like a burrow or a hole under a rock; these are just a few.
And that spot is colder or warmer than the surrounding environment because it's a microclimate.
A microclimate is a group of climate conditions that affect a localized area, weather features like temperature, wind, moisture and so on.
And when I say localized, I mean really localized, because microclimates can be, as the name suggests, pretty small, even less than a square meter.
And microclimates are affected by a huge number of other variables.
Obviously weather conditions in the surrounding area are a factor.
But other aspects of the location like... um... the elevation of the land, the plant life nearby and so on have a substantial effect on microclimates.
And of course the human development in the area... um... a road will affect a nearby microclimate.
It's also interesting to note that microclimates that are near each other can have very different conditions.
In the forest for example, there can be a number of very different microclimates close to each other because of all the variables I just mentioned.
So how does a hole in the ground, a burrow, stay cool in a hot climate?
Well, since cold air sinks, and these spots are shaded, they are usually much cooler than the surrounding area.
And these spots are so important because many animals rely on microclimates to regulate their body temperature.
Um for instance there is a species of squirrel in the western part of the United States that can get really hot when they are out foraging for food, so they need a way to cool down.
So what do they do? They go back to their own burrow.
Once they get there, their body temperatures decrease very very quickly.
The trip to the burrow prevents the squirrel from getting too hot.
But squirrels are mammals right?
I thought mammals regulated their temperature internally.
Mammals do have the ability to regulate their body temperature, but not all can do it to the same degree, or even the same way.
Like when you walk outside on a hot day, you perspire and your body cools itself down, a classic example of how a mammal regulates its own body temperature.
But one challenge that squirrels face, well many small mammals do, is that because of their size, sweating would make them lose too much moisture; they dehydrate.
But on the other hand, their small size allows them to fit into very tiny spaces.
So for small mammals, microclimates can make a big difference.
They rely on microclimates for survival.
So cold-blooded animals like reptiles, they can't control their own body temperature, so I can imagine the effect a microclimate would have on them.
Yes. Many reptiles and insects rely on microclimates to control their body temperature.
A lot of reptiles use burrows or stay under rocks to cool down.
Of course with reptiles it's a balancing act.
Staying in the heat for too long can lead to problems, but staying in the cold can do the same.
So reptiles have to be really precise about where they spend their time, even how they position their bodies.
And when I say they are precise, I mean it.
Some snakes will search out a place under rocks of a specific thickness because too thin a rock doesn't keep them cool enough and too thick a rock will cause them to get too cold.
That level of precision is critical to the snake for maintaining its body temperature.
And even microscopic organisms rely on microclimates for survival.
Think about this. Decomposing leaves create heat that warms the soil.
The warm soil in turn affects the growth, the conditions of organisms there, and those organisms then affect the rate of decomposition of the leaves.
So a microclimate can be something so small and so easily disturbed that even a tiny change can have a big impact.
If someone on a hike knocks a couple of rocks over, they could be unwittingly destroying a microclimate that an animal or organism relies on. "
L14C2
"Listen to a conversation between a student and his faculty adviser.Hi, Steve, I schedule this appointment, cause it has been a while since we touched base.
I know, I have been very busy. A friend of mine works on the school paper.
He asks me if I would like to try to reporting so I did and I really love it.
Hey... that's sounds great!
Yeah... the first article I wrote, it was profile of the chemistry professor_ the one who was the named teacher of the year.
My article ran on the front page.
When I saw my name, I mean my byline in print, I was hooked.
Now I know this is what I want to do - be a reporter.
Isn't it great to discover something that you really enjoy?
And I read that article too. It was very good.
To be honest, the articles got a lot of editing. In fact I barely recognized a couple of paragraphs.
But the editor explained why the changes were made.
I learned a lot and my second article didn't need nearly as many changes.
Sound like you got a real knack for this.
Yeah... anyway, I am glad you schedule this meeting because I want to change my major to journalism now.
Um... the university doesn't offer major in journalism.
Oh no...
But...
I... I mean... should I transfer to another school, or major in English?
Er... wait a minute. Let me explain why the major isn't offered.
Editors at the newspapers... editors... um...
I mean when you apply for a reporting job, editors look at the two things: they want to see clips, you know, some of your published articles; they also want you to try out. They'll give you an assignment like... covering a press conference or some other event, then see if you can craft the story about it, accurately, on deadline.
So they don't even to look at my major?
It is not that they don't look at it... it is... well, having a degree in something other than journalism should actually work to your advantage.
How?
Most journalists specialized these days. They only write about science or business or technology for example.
Is there a type of reporting you think you may like to specialize then?
Well... I think it can be really cool to cover the Supreme Court.
I mean... their decision affects so many people.
That is really a goal worth striving for.
So, why not continue major in political science?
And as electives, you could take some Pre-Law classes like constitutional Law, and as for you work on the student newspaper paper, maybe they let you cover some local court cases once that the student and professor here would want to read about.
Do you know of any?
I do, actually. There is case involving this computer software program that one of our professors wrote.
The district courts decide in if the university is entitle to any of the professors' profits.
Wow... I will definitely follow up on that! "
L14L3
"Listen to part of a lecture in an astronomy class.OK, last time we talked about ancient agricultural civilizations that observed the stars and then used those observations to keep track of the seasons.
But today I want to talk about the importance of stars for early seafarers, about how the fixed patterns of stars were used as navigational aids.
OK, you've all heard about the Vikings and their impressive navigation skills, but the seafaring peoples of the Pacific islands, the Polynesians and the Micronesians, were quite possibly the world's greatest navigators.
Long before the development of, uh, advanced navigational tools in Europe, pacific islanders were travelling from New Zealand to Hawaii and back again, using nothing but the stars as their navigational instruments.
Um, the key to the pacific islanders' success was probably their location near the equator.
What that meant was that the sky could be partitioned, divided up, much more symmetrically than it could farther away from the equator.
Unlike the Vikings, early observers of the stars in Polynesia or really anywhere along the equator would feel that they were at the very center of things, with the skies to the north and the skies to the south behaving identically, they could see stars going straight up in the east and straight down in the west.
So it was easier to discern the order in the sky than farther north or farther south, where everything would seem more chaotic.
Take the case of the Gilbert Islands, they are part of Polynesia, and lie very close to the equator.
And the people there were able to divide the sky into symmetrical boxes, according to the main directions, north, east, south and west.
And they could precisely describe the location of a star by indicating its position in one of those imaginary boxes.
And they realized that you had to know the stars in order to navigate.
In fact there was only one word for both in the Gilbert Islands, when you wanted the star expert, you ask for a navigator.
Um, islanders from all over the pacific learned to use the stars for navigation, and they passed this knowledge down from generation to generation.
Some of them utilized stone structures called stone canoes, ah, and these canoes were on land, of course, and you can still see them on some islands today.
They were positioned as if they were heading in the direction of the points on the sea horizon where certain stars would appear and disappear during the night.
And, um, young would-be navigators set by the stones at night and turned in different directions to memorize the constellations they saw, so they could recognize them and navigate... by them later on when they went out to sea.
One important way the Polynesians had for orienting themselves was by using zenith stars.
A zenith star was a really bright star that would pass directly overhead at particular latitude... at a particular distance from the equator, often at a latitude associate with some particular pacific island.
So the Polynesians could estimate their latitude just by looking straight up, by observing whether a certain zenith star passed directly overhead at night.
They'd know if they have reached the same latitude as a particular island they were trying to get to.
Um, another technique used by the Polynesians was to look for a star pair, that's two stars that rise at the same time, or set at the same time, and navigators could use these pairs of stars as reference points, because they rise or set together only at specific latitudes.
So navigators might see one star pair setting together.
And, uh... would know how far north or south of the equator they were.
And if they kept on going, and the next night they saw the pairs of stars setting separately, then they would know that they were at a different degree of latitude.
So looking at rising and setting star pairs is a good technique.
Um... actually it makes more sense with setting stars.
They can be watched instead of trying to guess when they'll rise.
Uh, OK, I think all this shows that navigating doesn't really require fancy navigational instruments.
The peoples of the pacific islands had such expert knowledge of astronomy as well as navigation that they were able to navigate over vast stretches of Open Ocean.
Uh, it's even possible that Polynesian navigators had already sailed to the Americas, centuries before Columbus. "
L14L4
"Listen to part of lecture in an archaeology class.When we think of large monumental structures built by early societies and Egyptian pyramid probably comes to mind.
But there are some even earlier structures in the British Isles also worth discussing, and besides the well-known circle of massive stones of Stonehenge which don't get me wrong is remarkable enough, well, other impressive Neolithic structures are found there too.
Oh, yes, we are talking about the Neolithic period here, also called the new Stone Age, which was the time before stone tools began to be replaced by tools made of bronze and other metals.
It was about 5,000 years ago, even before the first Egyptian pyramid that some of amazing Neolithic monuments - tombs, were erected at the various sites around Ireland Great Britain and coastal Islands nearby.
I am referring particular to structures that in some cases, look like ordinary natural hills.
But were definitely built by humans, well-organized communities of humans to enclose a chamber or room within stone walls and sometimes with a high, cleverly designed ceiling of overlapping stones.
These structures are called Passage Graves, because the inner chamber, sometime several chambers in fact, could only be entered from the outside through a narrow passageway.
Excuse me, professor, but you said Passage Graves.
Were these just monuments to honor the dead buried there or were they designed to be used somehow by the living?
Ah, yes! Good question, Michael. Besides being built as tombs, some of these Passage Graves were definitely what we might call Astronomical Calendars, with chambers that were flooded with some light on the certain special days of the year, which must've seem miraculous and inspired a good deal of religious wonder.
But research indicates that not just light but also the physics of sound help to enhance this religious experience.
How so?
Well, first the echoes.
When religious leaders started chanting with echoes bouncing off the stone walls over and over again, it must seem like a whole chorus of other voices, spirits of Gods maybe join in.
But even more intriguing is what physicists called Standing Waves.
Basically, the phenomenon of Standing Waves occurs when sound waves of the same frequency reflect off the walls and meet from opposite directions.
So, the volume seems to alternate between very loud and very soft.
You can stand quite near a man singing in a loud voice and hardly hear him.
Yet step a little further way and this voice is almost deafening.
As you move around the chamber, the volume of the sound goes way up and way down, depending on where you are in these standing waves.
And often the acoustics makes it hard to identify where sounds are coming from.
It is as if powerful voices that are speaking to you or chanting from inside your own head.
This had to engender powerful sense of all Neolithic worshipers.
And another bit of physics I played here is something called Resonance.
I am no physicist, but well I imagine you have all blown air over the top of an empty bottle and heard the sound it makes.
And you probably notice that depending on its size, each empty bottle plays one particular musical note.
or as a physicist might put it, each bottle resonates at a particular frequency.
Well, that's true of these chambers too.
If you make a constant noise inside the chamber, maybe by steadily beating drum at a certain rate, a particular frequency of sound will resonate.
We will ring out intensely, depending on the size of chamber.
In some of the large chambers though, these intensified sound may be too deep for us to hear, we can feel it.
We are mysteriously agitated by it, but it is not a sound our ears can hear.
The psychological effects of all these extraordinary sounds can be profound, especially when they seem so disconnected from human doing the drumming or chanting.
And there can be observable physical effects on people too.
In fact, the sounds can cause headaches, feelings of dizziness, increase heart rate, that sort of thing, you see.
Anyway, what was experienced inside one of these Passage Graves clearly could be far more intense than the everyday reality outside, which made them very special places.
But back to your question, Michael, as to whether these graves were designed to be used by the living, well, certainly with regard to astronomical or calendar function,that seems pretty obvious, and I want to go into more detail on that now. "
L15C1
"Listen to a conversation between a Student and the faculty Advisor of the campus newspaper.Hi! I talked to someone on the phone a couple of weeks ago, Anna, I think it was?
I'm Anna, the faculty Advisor.
Oh, great! I'm Peter Murphy. You probably don't remember me, but...
No! No! I remember you.
You were interested in working for the paper.
Yeah, as a reporter.
That's right. You're taking a journalism class and you've done some reporting before in high school, right?
Wow, you have a good memory.
Well we haven't had many students applying lately.
So... so anyway, you still want to do some reporting for us?
Yeah, if you have room for me on the staff.
Well we always need more reporters, but you know, we don't pay anything, right?
Yeah, I know, but I huh... I'd like the experience.
It would look good on my resume.
Absolutely! Let's see.
I think I told you that we ask prospective reporters to turn in some outlines for possible articles.
Yeah, I sent them in about a week ago, but I haven't heard anything back yet, so, so I thought I'd stop by and see, but I guess you haven't looked at them yet.
Oh, Max, the news editor. He looks at all the submissions.
Oh, so he hasn't made any decision about me yet?
Well I just got here a few minutes ago... haven't been in for a couple of days.
Just give me a second to check my e-mail.
Uh... here is a message from Max. Let' s see.
Well it seems you've really impressed him.
He says it would be wonderful if you could join our staff.
Oh, great! When can I start?
Well, you turned in an outline on something to do with the physics department?
Yeah, they're trying to come up with ways to get more students to take their introductory courses.
Right, well, apparently, nobody else is covering that story, so he wants you to follow up on it.
OK. Uh... what about the other outline I sent in, about the proposed increase in tuition fees?
Oh, it looks like we've got that covered.
So I am starting with an article about the physics department.
I guess I'd better get to work.
Do you have any advice on how I should cover the story?
Well, Max will want to talk to you but I am sure he will tell you to find out things like why the physics department's worried about enrollment.
Has the number of Students been getting smaller in recent years? By how much?
What kinds of plans are they considering to address this problem?
Right, some of those issues are already in what I proposed.
And you'll want to do some interviews, you know, what do the Professors think of the plans, what do the students think you get the idea but...
But wait till I talk to Max before proceeding.
Right, he'll cover everything you need to know to be a reporter for us.
Can you come back this afternoon? He will be here until 5 o'clock. "
L15L1
"Listen to part of a lecture in a psychology class.For decades, psychologists have been looking at our ability to perform tasks while other things are going on, how we are able to keep from being distracted and what the conditions for good concentration are.
As long ago as 1982, researchers came up with something called the CFQ, the Cognitive Failures Questionnaire.
This questionnaire asks people to rate themselves according to how often they get distracted in different situations, like hum... forgetting to save a computer file because they had something else on their mind or missing a speed limit sign on the road. John?
I've lost my share of computer files, but not because I' m easily distracted. I just forget to save them.
And that's part of the problem with the CFQ.
It doesn't take other factors into account enough, like forgetfulness.
Plus you really can't say you are getting objective scientific results from a subjective questionnaire where people report on themselves.
So it's no surprise that someone attempted to design an objective way to measure distraction.
It's a simple computer game designed by a psychologist named Nilli Lavie.
In Lavie's game, people watch as the letters N and X appear and disappear in a certain area on the computer screen.
Every time they see an N, they press one key, and every time they see an X they press another, except other letters also start appearing in the surrounding area of the screen with increasing frequency which creates a distraction and makes the task more difficult.
Lavie observed that people's reaction time slowed as these distractions increased.
Well that's not too surprising, is it?
No, it's not.
It's the next part of the experiment that was surprising.
When the difficulty really increased, when the screen filled up with letters, people got better at spotting the Xs and Ns.
Why do you think that happened?
Well, maybe when we are really concentrating, we just don't perceive irrelevant information.
Maybe we just don't take it in, you know?
Yes, and that's one of the hypotheses that was proposed, that the brain simply doesn't admit the unimportant information.
The second hypothesis is that, yes, we do perceive everything, but the brain categorizes the information, and whatever is not relevant to what we are concentrating on gets treated as low priority.
So Lavie did another experiment, designed to look at the ability to concentrate better in the face of increased difficulty.
This time she used brain scanning equipment to monitor activity in a certain part of the brain, the area called V5, which is part of the visual cortex, the part of our brains that processes visual stimuli.
V5 is the area of the visual cortex that's responsible for the sensation of movement.
Once again, Lavie gave people a computer-based task to do.
They had to distinguish between words in upper and lower-case letters or even harder, they had to count the number of syllables in different words.
This time the distraction was a moving star field in the background, you know, where it looks like you are moving through space, passing stars.
Normally area of V5 would be stimulated as those moving stars are perceived and sure enough, Lavie found that during the task area of V5 was active.
So people were aware of the moving star field.
That means people were not blocking out the distraction.
So doesn't that mean that the first hypothesis you mentioned was wrong, the one that says we don't even perceive irrelevant information when we are concentrating?
Yes that's right, up to a point, but that's not all.
Lavie also discovered that as she made the task more difficult, V5 became less active, so that means that now people weren't really noticing the star field at all.
That was quite a surprise and it proved that the second hypothesis that we do perceive everything all the time but the brain categorizes distractions differently, well, that wasn't true either.
Lavie thinks the solution lies in the brain's ability to accept or ignore visual information.
She thinks its capacity is limited. It's like a highway.
When there are too many cars, traffic is stopped. No one can get on.
So when the brain is loaded to capacity, no new distractions can be perceived.
Now that maybe the correct conclusion for visual distractions, but more research is needed to tell us how the brain deals with, say, the distractions of solving a math problem when we are hungry or when someone is singing in the next room. "
L15L2
"Listen to part of a lecture in a geology class.As geologists we examine layers of sediment on the Earth's surface to approximate the dates of past geologic time periods.
um, sediment as you know is material like sand, gravel, fossil fragments that is transported by natural processes like wind, water flow or the movement of glaciers.
So a sediment is transported and then deposited and it forms layers on the Earth's surface over time.
We examine these layers to learn about different geologic time periods including when they began and ended.
For example, from about 1.8 million years ago to around 11 thousand years ago was the Pleistocene Epoch.
The Pleistocene Epoch was an ice age.
During this epoch, sediment was made by the kind of erosion and weathering that happens when the climate is colder, and part of those sediments are fossils of plants and animals that lived at that time.
The Holocene Epoch followed the Pleistocene Epoch when the Earth's climate warmed up around 11 thousand years ago.
The Holocene Epoch is characterized by different sediments, ones that form when the climate is warmer.
Because the climate changed, the types of plants and animals changed also.
Holocene sediments contain remnants of more recent plants and animals, so it's pretty easy to differentiate geologically between these two epochs.
Now there is growing evidence that the presence of humans has altered the earth so much that a new epoch of geologic history has began - the Anthropocene Epoch, a new human-influenced epoch.
This idea that we have entered a new Anthro-pocene Epoch was first proposed in 2002.
The idea is that around the year 1800 CE the human population became large enough, around a billion people, that its activities started altering the environment.
This was also the time of the industrial revolution, which brought a tremendous increase in the use of fossil fuels such as coal.
The exploitation of fossil fuels has brought planet wide developments: industrialization, construction, uh, mass transport.
And these developments have caused major changes like additional erosion of the Earth's surface and deforestation.
Also, things like the damming of rivers has caused increased sediment production, not to mention the addition of more carbon dioxide and methane in the atmosphere.
Naturally all these changes show up in recent sediments.
And these sediments are quite different from pre year 1800 sediment layers.
Interestingly there's some speculation that humans started having a major impact on Earth much earlier, about 8000 years ago.
That's when agriculture was becoming widespread.
Early farmers started clearing forests and livestock produced a lot of extra methane.
But I want to stress that this is just a hypothesis.
The idea that early humans could have had such a major effect, well I'm just not sure we can compare it with the industrial age.
Geologists in the far future will be able t o examine the sediment being laid down today, whereas right now we can say the yes, human impact on the Earth is clear.
It'll be future researchers who have a better perspective and will be able to really draw a line between the Holocene and the Anthropocene epochs. "
L15C2
"Listen to part of a conversation between a Student and her biology professor.Hi Samantha, how did your track meet go?
Great! I placed first in one race and third in another.
Congratulations! You must practice a lot.
Three times a week pre-season, but now that we're competing every weekend, we practice 6 days a week from 3:30 till 5:00.
Athletics place a heavy demand on your time, don't they?
Yeah, but I really love competing, so...
You know I played soccer in college and my biggest challenge, and I didn't always succeed, was getting my studying in during soccer season. Are you having a similar...
No, I... I really do make time to study.
And I actually study more for this class than I do for all my other classes.
But I didn't see the grade I expected on my mid-term exam, which is why I came by.
Well, you didn't do badly on the exam, but I agree it did not reflect your potential.
I say this because your work on the lab project was exemplary.
I was so impressed with the way you handle the microscope and the samples of onion cells, and with how carefully you observed and diagramed and interpreted each stage of cell division.
And I don't think you could have done that if you hadn't read and understood the chapter.
I mean it seemed like you really had a good understanding of it.
I thought so too, but I missed some questions about cell division on the exam.
So what happened?
I just sort of blanked out, I guess.
I had a hard time remembering details.
It was so frustrating.
Alright, let's back up.
You say you studied, where, at home?
At my kitchen table actually.
And that's supposed to be a quiet environment?
Not exactly. My brother and parents try to keep it down when I am studying, but the phone pretty much rings off the hook, so...
So you might try a place with fewer distractions, like the library...
But the library closes at mid-night, and I like to study all night before a test, you know, so everything is fresh in my mind.
I studied six straight hours the night before the mid-term exam.
That's why I expected to do so much better.
Oh ok.
You know that studying six consecutive hours is not equivalent to studying one hour a day for six days.
It isn't?
No. There is research that shows that after about an hour of intense focus, your brain needs a break.
It needs to, you know, shift gears a little.
Your brain's ability to absorb information starts to decline after about the first hour.
So if you are dealing with a lot of new concepts and vocabulary, anyway, if you just reviewed your notes, even 20 minutes a day, it'd be much better than waiting until the night before an exam to try and absorb all those details.
Oh, I didn't realize.
Think of your brain as a muscle.
If you didn't practice regularly with your track team, and then tried to squeeze in three weeks worth of running practice just the day before a track meet, how well do you think you'd perform in your races? "
L15L3
"Listen to part of a lecture in an art history class.Now in Europe in the Middle Ages before the invention of printing and the printing press, all books, all manuscripts were hand-made.
And the material typically used for the pages was parchment, which is animal skin that stretched and dried under tension.
So it becomes really flat and can be written on.
During the 1400s, when printing was being developed, paper became the predominant material for books in Europe, but prior to that, it was parchment.
Parchment is durable, much more so than paper, and it could be reused which came in handy since it was a costly material and in short supply.
So it wasn't uncommon for the scribes or monks who produce the manuscripts.
Ah, remember before printing books were made mainly in monasteries.
Well, the scribes often recycled the parchment that had been used for earlier manuscripts.
They simply erased the ink off the parchment and wrote something new in its place.
A manuscript page that was written on, erased and then used again is called a palimpsest.
Palimpsests were created, well, we know about two methods that were used for removing ink from parchment.
In the late Middle Ages, it was customary to scrape away the surface of the parchment with an abrasive, which completely wiped out any writing that was there.
But earlier in the Middle Ages, the original ink was usually removed by washing the used parchment with milk. That removed the ink.
But with the passing of time, the original writing might reappear.
In fact, it might reappear to the extent that scholars could make it out and even decipher, the original text.
Perhaps, the most famous example is the Archimedes' palimpsest.
Archimedes lived in Greece around 200 B.C.E, and as you probably know, he's considered one of the greatest Mathematicians who ever lived, even though, many of his writings had been lost, including what many now think to be his most important work called The Method.
But in 1998, a book of prayers from the Middle Ages sold in an art auction for a lot of money, more money than anyone would pay for a damaged book from the 12th century.
Beautiful or not, why?
It had been discovered that the book was a palimpsest, and beneath the surface writing of the manuscript laid, guess what?
Mathematical theorems and diagrams from Archimedes.
Archimedes' writings were originally done on papyrus scrolls.
Then in the 10th century, a scribe made a copy on parchment of some of his texts and diagrams including, as it turns out, The Method.
This was extremely fortunate, since later on, the original papyrus scrolls disappeared.
About 200 years later in the 12th century, this parchment manuscript became a palimpsest when a scribe used the parchment to make a prayer book.
So the pages, the pieces of parchment themselves, had been preserved.
But the Archimedes' text was erased and written over, and no one knew it existed.
It wasn't until 1906 that a scholar came across the prayer book in a library and realized it was a palimpsest, and the underlying layer of texts could only have come from Archimedes.
That was when his work The Method was discovered for the first time.
Um... the palimpsest then went through some more tough times, but eventually it ended up in an art auction where was bought and then donated to an art museum in Baltimore, for conservation and study.
To avoid further damage to the manuscript, the research team at the art museum has had to be extremely selective in the techniques they used to see the original writing.
They've used ultraviolet light and some other techniques, and if you're interested in that sort of thing, you can learn more about it in our art conservation class.
But actually, it was a physicist who came up with a method that was a breakthrough.
He realized that the iron in the ancient ink would display if it was exposed to a certain X-ray imaging method, and except for small portions of the texts that couldn't be deciphered, this technique has been very helpful in seeing Archimedes' texts and drawings through the medieval overwriting. "
L15L4
"Listen to part of a lecture in a biology class.OK. We've been talking till now about the two basic needs of a biological community - an energy source to produce organic materials, you know ah, food for the organisms, and the waste recycling or breakdown of materials back into inorganic molecules, and about how all this requires photosynthesis when green plants or microbes convert sunlight into energy, and also requires microorganisms, bacteria, to secrete chemicals that break down or recycle the organic material to complete the cycle.
So, now we are done with this chapter of the textbook, we can just review for the weekly quiz and move on to the next chapter, right?
Well, not so fast.
First, I'd like to talk about some discoveries that have challenged one of these fundamental assumptions about what you need in order to have a biological community.
And, well, there actually were quite a few surprises.
It all began in 1977 with the exploration of hydrothermal vents on the ocean floor.
Hydrothermal vents are cracks in the Earth's surface that occur, well, the ones we are talking about here are found deep at the bottom of the ocean.
And these vents on the ocean floor, they release this incredibly hot water, 3 to 4 times the temperature that you boil water at, because this water has been heated deep within the Earth.
Well about 30 years ago, researchers sent a deep-sea vessel to explore the ocean's depth, about 3 kilometers down, way deep to ocean floor.
No one had ever explored that far down before.
Nobody expected there to be any life down there because of the conditions.
First of all, sunlight doesn't reach that far down so it's totally dark.
There couldn't be any plant or animal life since there's no sunlight, no source of energy to make food.
If there was any life at all, it'd just be some bacteria breaking down any dead materials that might have fallen to the bottom of the ocean, And?
And what about the water pressure?
Didn't we talk before about how the deeper down into the ocean you go, the greater the pressure?
Excellent point!
And not only the extreme pressure, but also the extreme temperature of the water around these vents.
If the lack of sunlight didn't rule out the existence of a biological community down there then these factors certainly would, or so they thought.
So you are telling us they did find organisms that could live under those conditions?
They did indeed, something like 300 different species.
But... but how could that be? I mean without sunlight, no energy, no no...
What they discovered was that microorganisms, bacteria, had taken over both functions of the biological community - the recycling of waste materials and the production of energy.
They were the energy source.
You see, it turns out that certain microorganisms are chemosynthetic - they don't need sunlight because they take their energy from chemical reactions.
So, as I said, unlike green plants which are photosynthetic and get their energy from sunlight, these bacteria that they found at the ocean floor, these are chemosynthetic, which means that they get their energy from chemical reactions.
How does this work?
As we said, these hydrothermal vents are releasing into the ocean depth this intensely hot water and here is the thing, this hot water contains a chemical called hydrogen sulfide, and also a gas, carbon dioxide.
Now these bacteria actually combine the hydrogen sulfide with the carbon dioxide and this chemical reaction is what produces organic material, which is the food for larger organisms.
The researchers had never seen anything like it before.
Wow! So just add a chemical to a gas, and bingo, you've got a food supply?
Not just that! What was even more surprising were all the large organisms that lived down there.
The most distinctive of these was something called the tube worm.
Here, let me show you a picture.
The tube of the tube worm is really, really long.
They can be up to one and half meters long, and these tubes are attached to the ocean floor, pretty weird looking, huh?
And another thing, the tube worm has no mouth, or digestive organs.
So you are asking how does it eat?
Well, they have these special organs that collect the hydrogen sulfide and carbon dioxide and then transfer it to another organ, where billions of bacteria live.
These bacteria that live inside the tube worms, the tube worms provide them with hydrogen sulfide and carbon dioxide.
And the bacteria, well, the bacteria kind of feed the tube worms through chemosynthesis, remember, that chemical reaction I described earlier. "
L16C1
"Listen to a conversation between a Student and a facilities Manager at the university.Hi. I'm Melanie, the one who's been calling.
From the singing group, right?
From the choir.
Right, the choir.
It's nice to finally meet you in person. So, you are having problems with...
Noise. Like I explained on the phone we've always had our rehearsals in the Lincoln Auditorium every day at 3 o'clock and it's always worked just great.
But the past few weeks with the noise, it's been a total nightmare since constructions started next door on the science hall.
Oh, that's right. They're building that addition for new laboratories.
Exactly. Anyway, ever since they started working on it, it's been so noisy we can barely hear ourselves sing.
Let alone sing.
Forget about singing, I mean, we keep the windows down and everything, but once those bulldozers get going, I mean those machines are loud.
We've already had to cut short two rehearsals and we've got a concert in 6 weeks.
Well, that's not good.
I'm assuming you've tried to reschedule your rehearsals.
They don't do construction work at night.
I ran that by the group, but there were just too many, I mean evenings are really hard.
It seems like everyone in the choir already has plans and some even have classes at night.
And what about the music building?
You know, originally we were booked in one of the rehearsal rooms in the music building, but then we switched with the jazz ensemble.
They're a much smaller group and they said the acoustics, the sound in that room, was better for them.
So having us moved to a bigger space like the Lincoln Auditorium seemed like a reasonable idea.
But now...
All that noise.
I don't know, I just wonder if the jazz ensemble knew what was going to happen.
Well, that wouldn't be very nice.
No. But it really was quite a coincidence.
Anyway, now the music building's fully booked, mornings, afternoons, everything, we just need a quiet space. And it has to have a piano.
A piano. Of course some of the other auditoriums have pianos, but that's not going to be easy.
You think they're pretty booked up?
Probably. But it can't hurt to check.
What about Bradford Hall? I remember a piano in the old Student center there.
At this point, we'd be grateful for any quiet place.
Can you... How flexible can you be on times?
You said no evenings, but what if I can't find something open at 3 o'clock? Can you move earlier or later?
I wish I could say another time would be okay, but you know how it is, everybody's already got commitments for the whole semester, 2:30 or 3:30 would probably be okay, but I don't think we could go much outside that.
Well, check with me more on morning.
I should've found something by then.
It might not be ideal.
As long as it's got a piano and nobody's putting up a building next door, we'll be happy. "
L16L1
"Listen to a part of lecture in a geology class.Now there are some pretty interesting caves in parts of the western United States, especially in national parks.
There is one park that has over a hundred caves, including some of the largest ones in the world.
One of the more interesting ones is called Lechuguilla Cave.
Lechuguilla has been explored a lot in recent decades, it's a pretty exciting place I think.
It was mentioned only briefly in your books.
So can anyone remember what it said? Ellen?
It's the deepest limestone cave in the U.S.?
That's right.
It's one of the longest and deepest limestone caves not just in the country but in the world.
Now, what else?
Well, it was formed because of sulfuric acid, right?
That's it. Yeah, what happens is you have deep underground oil deposits and there are bacteria.
Here let me draw a diagram.
Part of the limestone rock layer is permeated by water from below.
Those curly lines are supposed to be cracks in the rock.
Below the water table and rock is oil.
Bacteria feed on this oil and release hydrogen sulfide gas.
This gas is hydrogen sulfide, rises up and mixes with oxygen in the underground water that sits in the cracks and fissures in the limestone.
And when hydrogen sulfide reacts with the oxygen in the water, the result of that is sulfuric acid, Ok?
Sulfuric acid eats away at limestone very aggressively.
So you get bigger cracks and then passageway is being formed along the openings in the rock and it's all underground. Ah yes, Paul?
So that water... It's not flowing, right? It's still?
Yes, so there are two kinds of limestone caves.
In about 90 percent of them, you have water from the surface, streams, waterfall or whatever - moving water that flows through cracks found in limestone.
It's the moving water itself that wears away at the rock and makes passageways.
Also, in surface water, there is a weak acid, carbonic acid, not sulfuric acid but carbonic acid that helps dissolve the rock.
With a little help from this carbonic acid, moving water forms most of the world's limestone caves.
When I was researching this for a study a few years ago, I visited a couple of these typical limestone caves, and they were all very wet, you know, from streams and rivers.
This flowing water carved out the caves and the structures inside them.
But not Lechuguilla?
Dry as a bone.
Well, that might be a bit of an exaggeration.
But it's safe to say that it's sulfuric acid and not moving water that formed Lechuguilla cave and those few other ones like it.
In fact, there is no evidence that flowing water has ever gone in or out of the cave.
So, it's like a maze.
You have passageways all around.
There are wide passages narrow ones at all different depths, like underground tunnels in the limestone.
And, since they were created underground and not from flowing surface water, not all these passageways have an opening to the outside world.
And... and there is other evidence that flowing water wasn't involved in Lechuguilla.
We've said that sulfuric acid dissolves limestone, right, and forms the passageways?
What else does sulfuric acid do? Paul?
Ah, leaves a chemical residue and...
Gypsum, right?
Yep, you'll find lots of gypsum deposited at Lechuguilla.
And, as we know, gypsum is soluble in water.
So if there were flowing water in the cave, it would dissolve the gypsum.
This is part of what led us to the realization that Lechuguilla is in that small group of waterless caves.
And Lechuguilla is pretty much dormant now.
It's not really forming any more.
But, there is other ones like it, for example, in Mexico, they are forming.
And when cave researchers go to explore them, they see and smell, the sulfuric acid and gases of... er... phew... now, something else, think of rotten eggs.
And, it's not just the smell.
Explorers even need to wear special masks to protect themselves from the gases in these caves. OK? Paul.
Yeah, how about what these caves look like on the inside?
Well, the formations... there is really something.
There's such variety there like nothing anywhere else in the world, some of them are elaborate looking, like decorations.
And a lot of them are made of gypsum and could be up to 20 feet long.
It's pretty impressive. "
L16L2
"Listen to part of a lecture in a music history class.Up until now in our discussions and readings about the Baroque early classical periods, we've been talking about the development of musical styles and genres within the relatively narrow social context of its patronage by the upper classes.
Composers, after all, had to earn a living and those who were employed in the services of a specific patron...
well, I don't have to spell it out for you, the likes and dislikes of that patron, this would've had an effect on what was being composed and performed.
Now, of course, there were many other influences on composers, um, such as the technical advances we've seen in the development of some of the instruments, uh, you remember the transverse flute, the clarinet and so on.
But I think if I were asked to identify a single crucial development in European music of this time, it would be the invention of the piano, which, interestingly enough also had a significant effect on European society of that time.
And I'll get to that in a minute.
Now, as we know, keyboard instruments existed long before the piano - the organ, which dates back to the Middle Ages, as do other keyboard instruments, such as the harpsichord which is still popular today with some musicians.
But none of these has had as profound an impact as the piano.
Um, the piano was invented in Italy in 1709.
The word piano is short for pianoforte, a combination of the Italian words for soft and loud.
Now, unlike the harpsichord which came before it, the piano is a percussion instrument.
You see, the harpsichord is actually classified as a string instrument, since pressing a key of a harpsichord causes a tiny quill that's connected to the key to pluck the strings that are inside the instrument, much the same as a guitar pick plucks the strings of a guitar.
But pressing the keys of a piano causes tiny felt-covered hammers to strike the strings inside the instrument, like drumsticks striking the head of a drum.
This striking action is why the piano is a percussion instrument instead of a string instrument.
Okay, so why is this so important?
Well, the percussive effect of those little hammers means that the pianist, unlike the harpsichordist, can control the dynamics of the sound - how softly or loudly each note is struck, hence the name, pianoforte, soft and loud.
Now artistically for both composers and performers this was a major turning point.
This brand new instrument, capable of producing loud and soft tones, greatly expanded the possibilities for conveying emotion.
This capacity for increased expressiveness, in fact, was essential to the Romantic style that dominated 19th century music.
But I'm getting ahead of myself.
Um, before we get back to the musical impact of this development, I wanna take a look at the social impact that I mentioned earlier.
Now, in the late 1700s and the earlier 1800s, the development of the piano coincided with the growth of the middle class in Western Europe.
Of course folk music, traditional songs and dances had always been part of everyday life.
But as mass production techniques were refined in the 19th century, the price of pianos dropped to the point that a larger proportion of the population could afford to own them.
As pianos became more available, they brought classical music, the music which previously had been composed only for the upper classes, into the lives of the middle class people as well.
One way in particular that we can see the social impact of this instrument is its role in the lives of women of the time.
Previously, it was quite rare for a woman to perform on anything, but maybe a harp or maybe she sang.
But suddenly in the 19th century it became quite acceptable, even, to some extent, almost expected for a middle-class European woman to be able to play the piano, partly because among upper-middle class women it was a sign of refinement.
But it was also an excellent way for some women to earn money by giving piano lessons.
And some women, those few who had exceptional talent and the opportunity to develop it, their lives were dramatically affected.
Later we'll be listening to works by a composer named Robert Schumann.
But let's now talk about his wife Clara Schumann.
Clara Schumann was born in Germany in 1819.
She grew up surrounded by pianos.
Her father sold pianos and both her parents were respected piano teachers.
She learned to play the instrument when she was a small child and gave her first public recital at age 9.
Clara grew up to become a well-known and respected piano virtuoso, a performer of extraordinary skill who not only gave concerts across Europe, but also was one of the first important female composers for the instrument. "
L16C2
"Listen to a conversation between a Professor and a Student.Jeff, I'm glad you drop by, I've been meaning to congratulate you on the class leadership award.
Thanks Professor Bronson, I was really happy to get it and a little surprised.
I mean, there were so many other people nominated.
Well, I know the award was well deserved.
Now, what can I do for you today?
I needed to talk to you about the medieval history test, you know, the one scheduled for Friday afternoon.
Yes?
Well, there is this trip that my French class is taking.
We are going to Montreal for the weekend.
Montreal? That's my favorite city.
What'll you be seeing there?
Uh, I'm not sure yet. Well, the reason, the main reason I wanna to go is that we'll be rooming with French speaking students there, you know, so we can get a chance to use our French to actually talk with real French speakers.
It sounds like a great opportunity.
But then, there is that test.
Yeah... but.. well, the thing is the bus leaves right in the middle of when our history class meets this Friday.
So, well, I was thinking maybe I could take the test on a different day like Monday morning during your office hours?
Eh... Monday morning... um... that would not be... oh wait, let me just see one thing.
Aha, okay. That's what I thought. So, for your class, I was planning a take-home exam, so you could just take the test along with you.
Let's see, I guess you could come to class Friday just to pick up the test.
That way you'd still make your bus, and then find some quiet time during your trip to complete it and you can bring it to class Wednesday when I'll be collecting everyone else's.
Hmm... um... during the trip, well, I guess I could.
So I should plan to take my books and stuff with me.
You'll definitely need your class notes.
I'm giving you several short essay questions to make you think critically about the points we've discussed in class, to state... uh state and defend your opinion, analyze the issues, speculate about how things might have turned out differently.
So, you see, I don't care if you look updates and that kind of thing.
What I want is for you to synthesize information to reflect back on what we've read and discussed and to form your own ideas, not just repeat points from the textbook.
Does that make sense?
Yeah, I think so.
You are looking for my point of view.
That's right. The mid-term exam showed me that you know all the details of who, where and when.
For this test, I want to see how you can put it all together to show some original thinking.
That's sounds pretty challenging, especially trying to work it into this trip.
But, yeah, I think I can do it.
I'm sure you can.
Thank you, Professor Bronson.
Have a great time in Montreal. "
L16L3
"Listen to part of lecture in a biology class.Ok, let's continue our discussion about animal behavior by taking about decisions the animals face, the complex ones.
Animals, even insects, carry out what look like very complex decision making processes.
The question is how.
I mean no one really thinks that, say a bee goes through weighing the pros and cons of pollinating this flower or that flower.
But then how do animals solve complex questions, questions that seem to require decision making.
The answer we'll propose of course is that their behavior is largely a matter of natural selection.
As an example, let's look at foraging behavior among beavers.
Beavers eat plants, mostly trees. And they also use trees and tree branches to construct their homes in streams and lakes.
So when they do forage for food and for shelter materials, they have to leave their homes and go up on land where their main predators are.
So there are a number of choices that have to be made about foraging.
So for example, um... they need to decide what kind of tree they should cut down.
Some trees have higher nutritional value than others, and some are better for building material, and some are good for both... um... aspen trees.
Beavers peel off the bark to eat and they also use the branches for building their shelters, so aspens do double duty.
But ash trees, beavers use ash trees only for construction.
Another decision is when to forage for food.
Should they go out during the day-time when it's hotter outside and they have to expend more energy or at night when the weather is cooler but predators are more active.
OK, but there are two more important issues, really the most central, the most important, OK?
First, let's say a beaver could get the same amount of wood from a single large tree when it has lots of branches as it could get from three small trees, which should it choose?
If it chooses one large tree, it' have to carry that large piece of wood back home, and lugging a big piece of wood 40 or 50 yards is hard work, takes a lot of energy.
Of course it'll have to make only one trip to get the wood back to the water.
On the other hand, if it goes for three small trees instead, it will take less energy per tree to get the wood back home but it'll have to make three trips back and forth for the three trees.
And presumably, the more often it wanders from home, the more it's likely to be exposed to predators.
So which is better, a single large tree or three small trees?
Another critical issue and it's related to the first, to the size issue, is how far from the water should it go to get trees.
Should it be willing to travel a greater distance for a large tree, since it'll get so much wood from it?
Beavers certainly go farther from the water to get an aspen tree than for an ash tree, that reflects their relative values.
But what about size? Will it travel farther for a larger tree than it will for a smaller tree?
Now I would have thought the bigger the tree, the farther the beaver would be willing to travel for it.
That make sense, right?
If you're going to travel far, make the trip worth it by bringing back most wood possible.
But actually, the opposite is true.
Beavers will cut down only large trees that are close to the water.
Though travel far, only to cut down certain small trees that they can cut down quickly and drag back home quickly.
Generally, the farther they go from the water, the smaller the tree they will cut down.
They're willing to make more trips to haul back less wood, which carries a greater risk of being exposed to predators.
So it looks as though beavers are less interested in minimizing their exposure to predators and more interested in saving energy when foraging for wood, which may also explain why beavers forage primarily during the evenings.
OK. So why does their behavior indicate more of a concern with how much energy they expend than with being exposed to predators?
No one believes a beaver consciously weighs the pros and cons of each of these elements.
The answer that some give is that their behavior has evolved over time.
It's been shaped by constraints over vast stretches of time, all of which comes down to the fact that the best foraging strategy for beavers isn't the one that yields the most food or wood.
It's the one that results in the most descendants, the most offspring.
So let's discuss how this idea works. "
L16L4
"Listen to part of a lecture in an art history class.OK, now uh, a sort of paradigmatic art form of the Middle Ages was stained glass art.
Stained glass of course is simply glass that has been colored and cut into pieces and re-assembled to form a picture or a decorative design.
To truly experience the beauty of this decorative glass you should see it with light passing through it, especially sunlight, which is why stained glass is usually used for windows.
But of course it has other uses, especially nowadays.
Uh, anyway, the art of making stained glass windows developed in Europe, uh, during the Middle Ages and was closely related to church building.
In the early 1100s a church building method was developed that reduced the stress on the walls so more space could be used for window openings allowing for large and quite elaborate window designs.
Back then, the artists made their own glass, but first they came up with the design.
Paper was scarce and expensive, so typically they drew the design onto a white tabletop.
They'd draw the principal outline but also outline the shape of each piece of glass to be used and indicate its color.
Now in the window itself the pieces of glass would be held together by strips of lead.
So in the drawing the artists would also indicate the location of the lead strips.
Then you could put a big piece of glass on the tabletop and see the design right through it and use it to guide the cutting of the glass into smaller pieces.
And the lead that was just to hold the pieces of glass together?
Well, lead is strong and flexible so it's ideal for joining pieces of glasses cut in different shapes and sizes.
But up to the 15th century the lead strips also helped create the design.
They were worked into the window as part of the composition.
They were used to outline figures to show boundaries just like you might use solid lines in a pencil drawing.
How did they get the color?
I mean how did they color the glass?
Well, up until the 16th century stained glass was colored during the glass making process itself.
You got specific colors by adding metallic compounds to the other glass making ingredients.
So if you wanted red you added copper if you wanted green you added iron.
You just added these compounds to the other ingredients that the glass was made of.
So each piece of glass is just one color?
Yes, at least up until the 16th century.
Then they started... um... you started to get painted glass.
Painted glass windows are still referred to as stained glass, but the colors were actually painted directly onto clear glass after the glass was made.
So um with this kind of stained glass you could paint a piece of glass with more than one color.
And with painted glass they still used the lead strips?
Yes, with really large windows it took more than one piece of glass, so you still needed lead strips to hold the pieces together.
But the painters actually tried to hide them.
So it was different from before when the lead strips were part of the design.
And it is different, because with painted glass the idea of light coming through to create the magical effect wasn't the focus any more.
The paint work was.
And painted glass windows became very popular.
In the 19th century, people started using them in private houses and public buildings.
Unfortunately, many of the original stained glass windows were thought to be old fashioned and they were actually destroyed, replaced by painted glass.
They actually broke them?
That showed good judgment, real foresight, didn't it?
Yes, if only they had known.
Uh, and it's not just that old stained glass is really valuable today, we lost possibly great artwork.
But luckily there was a revival of the early techniques in the mid-1800s and artists went back to creating colored glass and using the lead strips in their designs.
The effects are much more beautiful.
In the 19th century Louis Tiffany came up with methods to create beautiful effects without having to paint the glass.
He layered pieces of glass and used thin copper strips instead of lead, which let him make these really intricate flowery designs for stained glass, which are used in lamp shades.
You've heard of Tiffany lamp shades right?
These of course took advantage of the new innovation of electric lighting.
Electric light bulbs don't give quite the same effect as sunlight streaming through stained glass but it's close.
So layered glass, Tiffany glass, became very popular and still is today.
So let's look at some examples of different types of stained glass from each era. "
L17C1
"Listen to a conversation between a student and a professor.OK, let's see, right. Modern stagings of a Shakespearian classic.
Well, like I told you last week, I think that's a great topic for your paper.
So the title will be something like... um...
I'm not really sure. Probably something like 20th century stagings of A Midsummer Night's Dream.
Yes, I like that.
Straight forward into the point.So how is the research going?
Well, that's what I came to talk to you about.
I was wondering if you happen to have a copy of the Peter Brook production of A Midsummer Night's Dream in your video collection.
I've been looking for it everywhere, and I've have a really hard time tracking it down.
That's because it doesn't exist.
You mean in your collection ?Or at all?
I mean at all.
That particular production was never filmed or recorded.
Oh, no, I had no idea. From what I read, that production like, it influenced every other production of the play that came after it, so I just assumed it'd been filmed or videotaped.
Oh, it definitely was a landmark production and it's not like it ran for just a week.
But, either was never filmed, or if it was, the film has been lost.
It's ironic, because there is even a film about the making of the production.
But none of the production itself.
So now what will I do? If there's no video.
Well, think about it. This is the most important 20th century staging of A Midsummer Night's Dream, right?
But how can I write about Brook's interpretation of the play if I can't see his production?
Just because there's no recording doesn't mean you can't figure out how it influenced other productions.
I guess there is enough materials around, but it'll be a challenge.
True, but think about it, you're writing about dramatic arts, the theater, that's the nature of theater, isn't it?
You mean because it's live, when the performance has finished...
That's it, unless it's filmed, it's gone.
But that doesn't mean we can't study it.
And of course some students in this class are writing about productions in the 19th century, there're no videos of those.
You know, one of the challenges for people who study theater is to find ways of talking about something that's really so transient, about something that, in a sense, doesn't exist. "
L17L1
"Listen to part of lecture in an art history class.Good morning, ready to continue our review of prehistoric art?
Today, we will be covering the Upper Paleolithic Period, which I am roughly defining as the period from 35000 to 8000 B.C.
A lot of those cave drawings you have all seen come from this period.
But We also be talking about portable works of art, things that could be carried around from place to place.
Here is one example.
This sculpture is called ""the lady with the hood"" and it was carved from ivory, probably a mammoth's tusk.
Its age is a bit of a mystery.
According to one source, it dates from 22000 B.C.
But other sources claimed it has been dated closer to 30000 B.C. Em, Amy?
Why don't we know the exact date when this head was made?
That is a fair question.
We are talking about prehistory here.
So obviously, the artists didn't put a signature or a date on anything they did.
So how do we know when this figure was carved.
Last semester, I took an archaeology class, and we spend a lot of time on, eh, studying ways to date things.
One technique I remember was using the location of an object to dated it, like how deep it was buried.
That would be stratigraphy.
Stratigraphy is used for a dating portable art.
When archaeologists are digging at the site, they make very careful notes about which stratum, which layer of earth they find things in.
And, you know, the general rule is that the oldest layers are at the lowest level.
But this only works if the site hasn't been touched, and the layers are intact.
A problem with this dating method is that an object could have been carried around, used for several generations before it was discarded.
So it might be much older than the layer or even the site where it was found.
The stratification technique gives us the minimum age of an object, which isn't necessarily its true age.
Eh... Tom, in your archaeology class, did you talk about radiocarbon dating?
Yeah, we did.
That had to do with chemical analysis, something to do with measuring the amount of radiocarbon that's left in organic stuff.
Because we know how fast radiocarbon decays, we can figure out the age of the organic material.
The key word there is organic.
Is art made of organic material?
Well, you said the ""Lady with hood"" was carved out of ivory.
That's organic.
Absolutely. Any other examples?
Well, when they did those cave drawings.
Did they use like charcoal or maybe colors, dyes made from plants.
Fortunately they did, at least some of the time.
So it turns out that radiocarbon dating works for a lot of prehistoric art.
But again, there is a problem.
This technique destroys what it analyzes, so you have to chip off bits of object for testing.
Ah, obviously we are reluctant to do that in some cases.
And apart from that, there is another problems.
The date tells you the age of the material, say, a bone or a tree, the object is made from, but not the date when the artist actually created it.
So with radiocarbon dating, we get the maximum possible age for the object, but it could be younger.
OK, let's say our scientific analysis has produced an age range.
Can we narrow it down?
Could we look for similar styles or motifs?
You know, try to find things common to one time period.
We do that all the time.
And When we see similarities in pieces of art, we assume some connection in time or place.
But is it possible that we could be imposing our own values on that analysis?
Em, sorry, I don't get your point.
Well, we have all kinds of preconceived ideas about how artistic styles develop.
For example, a lot of people think the presence of details demonstrates that the work was done by a more sophisticated artist.
While a lack of detail suggests a primitive style.
But trends in art in the last century or so certainly challenge that idea.
Don't get me wrong though, analyzing the styles of prehistoric artifacts can help dating them.
But we need to be careful with the idea that artistic development occurs in a staight line, from simple to complex representations.
What your are saying is, I mean, I get the feeling that this is like a legal process, like building a legal case, the more pieces of evidence we have, the closer we get to the truth.
Great analogy.
And now you can see why we don't have an exact date for our sculpture ""the lady with the hood"". "
L17L2
"listen to part of lecture in Environmental science Class.OK, so we have been talking about theories that deal with the effects of human activity on the climate.
But today I'd like to talk a little bit about other theories that can explain variations in climate.
And one of the best known is called Milankovitch Hypothesis.
Um, now What the Milankovitch Hypothesis is about?
It says the variations in the Earth's movements, specifically in its orbit around the Sun, these variations lead to differences in the amount of solar energy that reaches Earth.
And these differences in amount of energy that's reaching Earth from the Sun,it is what causes variations in Earth's climate.
OK, a lot of people think of earth orbit around the sun as being perfectly circular, as smooth and as regular as um, say the way the hands move on a well-made watch.
But it just doesn't work that way.
You are probably aware that the Earth's orbit around the Sun is not shaped like a perfect circle.
It's more of an oval, it is elliptical.
But the shape of this orbit is not consistent; it varies over time over a period of about a hundred thousand years.
Sometimes it is a little more circular, sometimes it's more elliptical.
And when earth's orbit is more elliptical, Earth is actually closer to the Sun during part of the year, which makes Earth, and in particular, the Northern Hemisphere warmer.
And why is that important?
Well, because most of the planet's glaciers are in the Northern Hemisphere, and if it gets too warm then glaciers will stop forming.
And we already talked about how that affects Earth's overall temperature.
The second movement involved in the Hypothesis has to do with axial tilt, the tilt of Earth's axis, that imaginary pole that runs through the center of the earth.
And depending on the angle it tilts at, the seasons can be more or less severe.
It makes winters cooler and summers warmer, or, what some might say is doing now, it makes summers less hot, and more importantly, the winters less cold, which just like what I mentioned before, can also stop, prevent glaciers from forming, or cause them to melt.
There is the third movement the Hypothesis covers called Precession.
Precession basically is the change in the direction of Earth's axis of rotation.
It would take me a million years to explain even just the basics of this movement as Precession is quite complex.
And all these details are way beyond our scope.
What's important for you to understand is that these three movements, well they are cyclical and they work together to form, to produce complex but regular variations in Earth's climate and lead to the growth or decline the glaciers.
Now when Milankovitch first proposed this theory in the 1920s, many of the colleagues were skeptical.
Milankovitch did not have any proof.
Actually, there would not be any evidence to support the hypothesis until the 1970s, when oceanographers were able to drill deep into the seafloor and collect samples, samples which were then analyzed by geologists.
And from these samples, they were able to put together a history of ocean temperatures going back hundreds of thousands years.
And this showed that the earth climate had changed pretty much the way like Milankovitch Hypothesis suggested it would.
So this evidence was pretty strong support for Milankovitch's hypothesis, and by the year 1980s, most of people accepted this theory.
However, in the late 1980s, some scientists works exploring Devil's Hole, which is basically an extensive water-filled cave, far from the ocean in Nevada, in western United States.
Over million of years, ground water left deposits of a mineral called calcite on the rock within Devils' Hole.
And by studying these calcite deposits, we could determine the climate conditions, the temperatures over the last half million years.
Well, the Devil's Hole findings contradicted the one obtained during the 1970s, so basically, the question was, were the ages of one or both of the samples wrong?
Or were scientists misunderstanding the significance of the evidences.
Well, um, in the 1990s, a new study was done on the two samples, and the ocean floor sample's were found to be correct, as were the samples from Devil's Hole.
And now it is generally believed that the samples from Devil's Hole correspond to the variations in local climate in the Western United's States rather than global climate changes. "
L17C2
"Listen to a conversation between a student and a food service manager.Excuse me, Mrs. Hanson. My name is John, John Grant.
I work as a waiter in the campus dining hall, in the faculty dining room.
What can I do for you, John?
Well, I work week nights, except for Friday.
I was wondering if I could switch from working the dinner service to working at lunch.
That's going to be a problem.
I am afraid we don't have any openings at lunch time.
A lot of students want to work then, so it is really rare for us to have an open spot at that time of day.
Oh, you see, I have joined this group, the University Jazz Band, and the band's practice time is right around dinner time.
You know, it is so hard to get into this group, I must have auditioned like ten times since I have been at the school, so I am...
Anyway, so I was really hoping to have the dinner hour free so I can go to practice.
Well, we do have other open times, like breakfast.
Uh, that won't work, I am sorry.
I mean that, I can't work that early. I have this very important music class I got to take, and it is like, first thing in the morning.
Well, if you don't mind working in the kitchen, we've got some pretty flexible hours for students doing food-prep work, anything from early morning to late afternoon.
What's prep work?
You prepare food for the cooks. You know, like cutting up vegetables for soup, or cleaning greens for salads.
Oh, that doesn't sound, I mean... Being a waiter, I get to see a lot of the professors, like in a different light, we joke around a little you know.
In the classroom, they always have to be pretty formal, but...
Well, the money is no different since we pay students the same amount for any of the jobs here in food service, so it's up to you.
Oh, man, I always thought that sacrificing for my art, well, that'd mean working long hours as a musician for, like, no money.
I didn't think it'd mean, peeling carrots.
Let me see, I am offering you something that has the hours you want, it is right here on campus, and you make as much money as you did being a waiter, quite a sacrifice.
I am sorry, I know you are just trying to help, I guess I should look into the food-prep job.
Ok, then, I'll tell the kitchen manager that you will stop by tomorrow to talk about the job and schedule your hours.
And I will let the dining hall manager know that he needs to find a new waiter for the evening.
Oh, ok, I guess that's it. Thanks, Mrs. Hanson. "
L17L3
"Listen to part of a lecture in a history class. The professor has been discussing ancient Egypt.Ok, so one of the challenges that faced ancient civilizations like Egypt was timekeeping, calendars.
When you have to grow food for whole cities of people, it is important to plant your crops at the right time.
And when you start having financial obligations, rents, taxes, you have to keep track of how often you pay.
So today we will look at how the Egyptians addressed these problems.
In fact, they ended up using two different calendars, one to keep track of the natural world, or their agriculture concerns, and another one, that was used to keep track of the business functions of the Kingdom.
So let's take a look at the hows and whys of one ancient Egyptian calendar system, starting with the Nile River.
Why the Nile?
Well, there's no other way to put it.
Egyptian life basically revolved around the mysterious rise and fall of the river.
The success of their agriculture system depended upon them knowing when the river would change.
So, naturally, their first calendar was divided up into three seasons, each based on the river's changes: inundation, subsidence and harvest.
The first season was the flooding, or inundation, when the Nile valley was essentially submerged in water for a few months or so.
And afterwards during the season of subsidence, the water would subside, or recede, revealing a new layer of fertile black silt and allowing for the planting of various crops.
And finally the time of the year would arrive when the valley would produce crops, such as wheat, barley, fruit, all ready to harvest.
Ok, so it was very important to the ancient Egyptians to know when their Nile based seasons would occur, their way of life depended upon it.
Now, the way they used to count time was based on the phases of the moon, which, regularly and predictably, goes through a cycle, starting with a new moon, then to a full moon, and back again to the new moon.
Now this cycle wes then used to determine the length of their month.
So, um, one lunar cycle was one Egyptian month, and about four of the months would constitute a season.
Now, 12 of these months was an approximately 354-day year.
So they had a 354-day agricultural calendar that was designed to help them determine when the Nile would inundate the land.
Well, of course it had to be more complicated than that.
The average amount of time between floodings wasn't actually 354 days.
I mean, although it varies, the average was clearly longer than 354 days.
So how did they keep this short calendar in step with the actual flooding of the Nile?
Well, their astronomers had discovered that at a certain time of year the brightest star, Sirius, would disappear.
Actually, it'd be hidden in the glare of the Sun.
And then, a couple of months later, one morning in the eastern sky just before dawn, Sirius would reappear.
And it happened regularly, about every 365 days.
Even more significantly, the reappearance of Sirius would occur around the same time as the Nile's flooding.
And this annual event is called a heliacal rising.
The heliacal rising was a fair indicator of when the Nile would flood.
The next new moon, after the heliacal rising of Sirius, which happened in the last month of the calendar year, marked the New Year.
And because the ancient Egyptians were using the lunar cycle in combination with this heliacal rising, some years ended up having 12 lunar months, while others had 13 lunar calender months, if Sirius didn't rise in the 12th month.
Even though the length of the agricultural calendar still fluctuated, with some years having 12 months and others having 13, it ended up being much more reliable than it was before.
They continually adjusted it to the heliacal rising of Sirius, ensuring that they never got too far off in their seasons.
This new calendar was ideal, because, well, it worked well for agricultural purposes as well as for knowing when to have traditional religious festivals.
So, that was their first calendar.
But was it any way to run a government?
They didn't think so.
For administrative purposes, it was very inconvenient to have years of different lengths.
So another calendar was introduced, an administrative one.
Probably soon after 3,000 BC, they declared a 365-day year, with 12 months per year, with exactly 30 days each month, with an extra 5 days at the end of each year.
This administrative calendar existed alongside the earlier agricultural and religious calendar that depended on the heliacal rising of Sirius.
This administrative calendar was much easier to use for things like scheduling taxes and other things that had to be paid on time.
Over time, the calendar got out of step with seasons and the flooding of the Nile, but for bureaucratic purposes, they didn't mind. "
L17L4
"Listen to part of a lecture in a biology class.Ok, now I want to talk about an animal that has a fascinating set of defense mechanisms.
And that's the octopus, one of the unusual creatures that live in the sea.
The octopus is prey to many species, including humans, so how does it escape its predators?
Well, let me back up here a second.
Anyone ever heard of Proteus?
Proteus was a God in Greek mythology who could change form.
He could make himself look like a lion or a stone or a tree, anything you wanted, and he could go through a whole series of changes very quickly.
Well, the octopus is the real world version of Proteus.
Just like Proteus, the octopus can go through all kinds of incredible transformations.
And it does this in three ways: by changing color, by changing its texture, and by changing its size and shape.
For me, the most fascinating transformation is when it changes its color.
It's a normal skin color, the one it generally presents, is either red or brown or even grey, and it 's speckled with dark spots.
But when it wants to blend in with its environment to hide from its enemies, it can take on the color of its immediate surroundings: the ocean floor, a rock, a piece of coral, whatever. Charles?
Do we know how that works, I mean, how they change colors?
Well, we know that the reaction that takes place is not chemical in nature.
The color changes are executed by two different kinds of cells in the octopus' skin, mainly by color cells on the skin's surface call chromatophores.
Chromatophores consist of tiny sacks filled with color dye.
There might be a couple hundred of these color sacks per square millimeter of the octopus' skin, and depending on the species, they can come in as many as five different colors.
Each one of these sacks is controlled by muscles.
If the muscles are relaxed, the sack shrinks, and all you see is a little white point.
But if the muscles contract, then the sack expands, and you can see the colors.
And by expanding different combinations of these color sacks to different degrees, the octopus can create all sorts of colors , yes, Elizabethe?
And just with various combinations of those five colors, they can recreate any color in their environment?
Well, they can no doubt create a lot with just those five colors, but you are right, maybe they can't mimic every color around them, so that's why the second kind of cell comes in.
Just below the chromatophores is a layer of cells that reflect light from the environment, and these cells help the octopus create a precise match with the colors that surround them.
The colors from the color sacks are supplemented with colors that are reflected from the environment, and that's how they are able to mimic colors with such precision.
So, that's how octopus mimic colors.
But they don't just mimic the colors in their environment; they can also mimic the texture of objects in their environment.
They have these little projections on their skin that allow them to resemble various textures.
The projections are called papillae.
If the octopus wants to have a rough texture, it raises the papillae.
If it wants to have a smooth texture, it flattens out the papillae, so it can acquire a smooth texture to blend in with the sandy bottom of the sea.
So the octopus has the ability to mimic both the color and the texture of its environment.
And it's truly amazing how well it can blend in with its surroundings.
You can easily swim within a few feet of an octopus and never see it.
I read that they often hide from predators by squirting out a cloud of ink, or something like that.
Yes. The octopus can release a cloud of ink if it feels threatened.
But it doesn't hide behind it, as is generally believed. Um, the ink cloud is... it serves to distract a predator while the octopus makes its escape.
Um, now there's a third way that octopus can transform themselves to blend in with or mimic their environment, and that's by changing their shape and size, well, at least their apparent size.
The muscular system of the octopus enables it to be very flexible to assume all sorts of shapes and postures.
So it can contract into the shape of a little round stone, and sit perfectly still on the seafloor.
Or it can nestle up in the middle of a plant and take the shape of one of the leaves.
Even Proteus would be impressed, I think. "
L18C1
"Listen to a conversation between a student and an administrator in the university employment office.Hi! I hope you can help me, I just transferred from Northeastern State University near Chicago.
Well welcome to Central University.
But Chicago is such a great city. Why did you leave?
Everyone asks that, It's my hometown, and it was sure convenient to go to a school nearby.
But Northeastern is still fairly small and it doesn't have the program I'm interested in.
I want to major in international studies.
And the only program in the State is here.
We do have a great program.
Well how did you get interested in international studies?
My family hosted a few foreign exchange students while I was growing up.
Then I took part in an international summer program after I graduated from high school.
I thought I really I like meeting people from all over, getting to know them.
OH! Ok! And that led you to our program.
Right now though I assume you are looking for a job.
Yeah, a part time job on campus.
I thought I'd save money, being away from the big city, but it doesn't seem to be working that way.
Anyway I'm not having much luck.
I'm not surprised, most of our campus jobs are taken in the first week or two of the semester.
What work experience have you had?
Well, I worked in the university library last year.
But I already checked at the library here.
They said their remaining positions were for work-study students getting financial aid.
I've never run into that before.
Well, I guess each school has its own policies.
Uh, we really don't have much right now.
You might be better of waiting until next semester.
If you really want something, how are your computer skills?
About average I'd say.
I helped teach some of the basic computer classes Northeastern offers for new users, if that helps any.
OK, The technology support department needs people to work its helpdesk.
It's basically a customer service job, answering questions, helping people solve their computer problems, give you a chance to develop your people skills.
Something every diplomat needs.
But is there some problem? I mean why is the job still open?
Well, they have extended hours, from 6 am to 2 am every day.
So they need a large staff.
But right now they only need people early mornings, late nights, and weekends.
You'd probably end up with a bit of everything rather than a regular spot.
On the bright side you'll probably be able to get some studying done between calls.
At least it could be a start and then you can try for better hours next semester.
Um, I see why the hours might be a problem.
But I guess I can't afford to be too picky if I want a job.
Still maybe we can work something out. "
L18L1
"Listen to part of a lecture in an Astronomy class.We are going to start a study of sunspot today.
And I think you will find it rather interesting.
Now I am going to assume that you know that sunspots, in the most basic terms, are the dark spots on the Sun's surface.
That'll do for now.
The ancient Chinese were the first to record observations of sunspots as the early as the year 165.
When later European astronomers wrote about sunspots, they didn't believe that the spots were actually on the Sun.
That's because of their belief at the time that the heavenly bodies, the Sun, Moon, Stars and Planets were perfect, without any flaws or blemishes.
So the opinion was the spots were actually something else, like shadows of planets crossing the Sun's face.
And this was thinking of European astronomers until the introduction of the telescope which brings us to our old friend, Galileo.
In the early 1600s, based on his observations of sunspots, Galileo proposed a new hypothesis.
He pointed out that the shape of sunspots, well, the sunspots weren't circular.
If they were shadows of the planets, they would be circular, right? So that was a problem for the prevailing view.
And he also noticed that the shape of the sunspots changed as they seemed to move across the Sun's surface.
Maybe a particular sunspot was sort of square, then later it would become more lopsided, then later something else.
So there's another problem with the shadow hypothesis.
Because the shape of a planet doesn't change.
What Galileo proposed was that sunspots were indeed a feature of the Sun, but he didn't know what kind of feature.
He proposed that they might be clouds in the atmosphere, the solar atmosphere.
Especially because they seemed to change shape, and there was no predicting the changes.
At least nothing Galileo could figure out, that random shape changing would be consistent with the spots being clouds.
Over the next couple hundreds years, a lot of hypotheses were tossed around, the spots were mountains or holes in the solar atmosphere through which the dark surface of the Sun could be seen.
Then in 1843, an astronomer named Heinrich Schwabe made an interesting claim.
Schwabe had been watching the Sun everyday that it was visible for 17 years, looking for evidence of a new planet.
And he started to keeping tracks of sunspots, mapping them, so he wouldn't confuse them with any potential new planet.
In the end, there was no planet.
But there was an evidence that the number of sunspots increased and decreased in a pattern.
A pattern that began repeating after 10 years, and that was a huge breakthrough.
Another astronomer named Wolf kept track of the Sun for an even longer period, 40 years actually.
So Wolf did 40 years of research, and Schwabe did 17 years of research, I think there is a lesson here.
Anyway, Wolf went through all records from various observatories in Europe, and put together a history of sunspot observations going back about 100 years.
From this information, he was able to confirm the existence of a pattern, a repeating cycle.
But Wolf detected an 11 years cycle not a 10 years cycle.
11 years cycles? Does that sound familiar to anyone? No?
Well, geomagnetic activity, the nature variations in Earth's magnetic field, it fluctuates in a 11 year cycles.
Well, we'll cover this later in this semester.
But for now, well, scientists in the late 19th century were aware of geomagnetic cycles.
So when they heard that the sunspots' cycle was also 11 years, well, they just had to find out what was going on.
Suddenly, everyone was doing studies of the possible relationship between the Sun and the Earth.
Did the sunspots cause geomagnetic fields or did the geomagnetic fields cause the sunspot? Or is there some other thing that caused both?
And astronomers did eventually figure out what sunspots had to do with the geomagnetic fields.
Actually, they are magnetic fields.
And the fact that sunspots are magnetic fields accounts for their dark appearance.
That's because magnetic fields reduce the pressure exerted on the gases inside of them, making the spots cooler than the rest of the Sun's surface.
And since they are cooler, they are darker. "
L18L2
"Listen to part of a lecture in an art history class.Today we'll continue our examination of ancient Roman sculpture.
We've already looked at portrait sculpture which are busts created to commemorate people who had died, and we've looked at relief sculpture, or sculpting on walls.
And today we'll look at yet another category of sculpture - copies.
Roman sculptors often made copies of famous Greek sculptures.
Why did they do that?
Well no one knows for sure.
You see, in the late 4th century B.C. the Romans began a campaign to expand the Roman Empire, and in 300 years they had conquered most of the Mediterranean area and parts of Europe.
You know the saying, ""To the victor belong the spoils""?
Well, the Roman army returned to Rome with many works of Greek art.
It's probably fair to say that the Romans were impressed by Greek art and culture and they began making copies of the Greek statues.
Now the dominant view in traditional art history is that Roman artists lacked creativity and skill, especially compared to the Greek artists who came before them.
Essentially, the traditional view, a view that's been prevalent for over 250 years, is that the Romans copied Greek sculptures because they couldn't create sculpture of their own.
But finally some contemporary art historians have challenged this view.
One is Elaine Gazda.
Gazda says that there might be other reasons that Romans made copies.
She wasn't convinced that it was because of a lack of creativity.
Can anyone think of another possible reason?
Well maybe they just admired these sculptures, you know, they liked the way they looked.
Yes. That's one of Gazda's points.
Another is that while nowadays reproduction is easy, it was not so easy in Roman times.
Copying statues required a lot of skill, time and effort.
So Gazda hypothesizes that copying didn't indicate a lack of artistic imagination or skill on the part of Roman artists, but rather the Romans made copies because they admired Greek sculpture.
Classical Greek statues represented an idealization of the human body and were considered quite beautiful at the time.
Gazda also believes that it's been a mistake to dismiss the Roman copies as, well, copies for copy's sake and not to consider the Roman function and meaning of the statues.
What do you mean the Roman function?
Weren't they just for decoration?
Well, not necessarily.
Under the Emperor Augustus at the height of the Roman Empire, portrait statues were sent throughout the empire.
They were supposed to communicate specific ideas about the emperor and the imperial family, and to help inhabitants of the conquered areas become familiar with the Roman way of life.
You know, Roman coins were also distributed throughout the empire.
Anybody care to guess what was on them?
The emperor's face? That's right!
The coins were easy to distribute and they allowed people to see the emperor or at least his likeness, and served as an additional reminder to let them know, well, who was in charge.
And the images helped people become familiar with the emperor.
Statues of him in different roles were sent all over the empire.
Now, actually some Roman sculptures were original but others were exact copies of Greek statues and some Roman sculptures were combinations of some sort.
Some combined more than one Greek statue and others combined a Greek god or an athlete with a Roman's head.
At the time of Julius Caesar, it wasn't uncommon to create statues that had the body of a god and the head of an emperor.
And the Romans were clever.
What they did was they made plaster casts from molds of the sculptures.
Then they shipped these plaster casts to workshops all over the empire, where they were replicated in marble or bronze.
And on some statues the heads were removable.
They could put an emperor's head on different bodies, showing him doing different things.
And then later when the time came they could even use the head of the next emperor on the same body. "
L18C2
"listen to a conversation between a student and his sociology professor.Well, I'm glad you redid your outline.
I fed a few comments, but nothing you have to act on.
It's in good enough shape for you to start writing you paper.
Thanks! At first I was afraid all that prep work would be a waste of time.
Well, especially with a challenging topic like yours: factors leading to the emergence of sociology as an academic discipline.
There's just so much history to consider; you could get lost without a solid outline.
So did you have a question?
Yeah, it's about... you mentioned needing volunteers for a research study?
Yep, it's not my study. It's my colleague's in the marketing department.
She needs people to watch various new TV programs that haven't been broadcast yet, then indicate on a survey whether they liked it, why, if they'd watch another episode.
It'd be kind of fun, plus participants get a $50 gift certificate.
Wow, well I like the sound of that.
But... so they are trying to predict if the shows are gonna succeed or fail, right, based on students' opinions?
Why would they care what we think?
Hey, don't sell yourself short.
People your age are a very attractive market for advertisers who promote their products on television.
The study is sponsored by a TV network.
If enough students don't like the show, the network may actually reconsider putting it on the air.
OK, well, how do I sign up?
You just add your name and phone number to this list and check a time slot, although it looks like the only times left are next Monday morning and Thursday evening.
Oh, well, I have marketing and economics Monday mornings and Thursday...
OH, you are taking the marketing class? Who's teaching it?
It's Professor Largin - Intro the Marketing.
He hasn't mentioned the study though.
Oh, well, the marketing department's pretty big.
I happen to be friends with a woman who is doing the TV study.
Ok, well, we don't want you missing class. How's Thursday?
Oh, I work from 5 till 9 that night.
Hum, no flexibility with your schedule? Where do you work?
At the Fox's diner, I'm a server.
Oh, I love Fox's. I eat there every week.
Maybe you could switch shifts with someone.
I'm still in training. And the only night my trainer works is Thursday.
Look! I know the owners there really well.
Why don't you let me give them a call and explain the situation?
OK! It'd be cool to be part of a real research study.
And the gift certificate wouldn't hurt either. "
L18L3
"listen to part of lecture in the European History class.In order to really study the social history of the Middle Ages, you have to understand the role of spices.
Now, this might sound a little surprising, even a little strange.
But what seem like little things now were back then actually rather big things.
So first let's define what a spice is.
Technically speaking, a spice is part of an aromatic plant that is not a leaf or herb.
Spices can come from tree bark like cinnamon, plant roots like ginger, flower buds like cloves.
And in the Middle Ages, Europeans were familiar with lots of different spices, most important being pepper, cloves, ginger, cinnamon, maize and nutmeg.
These spices literally dominated the way Europeans lived for centuries, how they traded and even how they used their imaginations.
So why this medieval fascination with spices?
We can boil it down to three general ideas briefly.
One was cost and rarity.
Uh two was exotic taste and fragrance.
And third, mysterious origins and kinds of mythical status.
Now for cost and rarity, spices aren't native to Europe and they had to be imported.
Spices only grew in the East Indies and of course transportation costs were astronomical.
So spices were incredibly valuable even from the very beginning.
Here is an example.
In 408 AD, the Gothic General who captured Rome demanded payment.
He wanted 5000 pounds of gold among other things but he also wanted 3000 pounds of pepper.
Maybe that would give you an idea of exactly where pepper stood at the time.
By the middle ages, spices were regarded as so important and expensive they were used in diplomacy, as gifts by heads of state and ambassadors.
Now, for the taste.
The diet then was relatively bland, compared to today's.
There wasn't much variety.
Especially the aristocracy who tended to eat a lot of meat, they were always looking for new ways to prepare it, new sauces, new tastes and this is where spices came in.
Now, this is a good point to mention one of the biggest myths about spices.
It's commonly said that medieval Europeans wanted spices to cover up the taste of spoiled meat.
But this isn't really true.
Anyone who had to worry about spoiled meat couldn't afford spices in the first place.
If you could afford spices, you could definitely afford fresh meat.
We also have evidence that various medieval markets employed a kind of police to make sure that people did not sell spoiled food, and if you were caught doing it, you were subject to various fines, humiliating public punishments.
So what actually was true was this, in order to have meat for the winter, people would preserved it in salt not a spice.
Spices actually aren't very effective as preservatives.
And throughout winter, they would eat salted meat, but the taste of the stuff could grow really boring and depressing after a while.
So the cook started looking for new ways to improve the taste and spices were the answer, which brings us to mysterious origins and mythical status.
Now the ancient Romans had a thriving spice trade and they sent their ships to the east and back.
But when Rome collapsed in the fifth century and the Middle Ages began, direct trade stopped, and so did that kind of hands-on knowledge of travel and geography.
Spices now came by way of the trade routes with lots of intermediaries between the producer and the consumer.
So these spices took on an air of mystery.
Their origins were shrouded in exotic travels.
They had the allure of the unknown, of wild places.
Myths grew up of fantasy lands, magical faraway places made entirely of food and spices.
Add to that, spices themselves had always been considered special or magical not just for eating and this was already true in the ancient world where legends about spices were abundant.
Spices inspired the medieval imagination.
They were used as medicines to ward off diseases, and mixed into perfumes, incenses.
They were used in religious rituals for thousands of years.
They took on a life of their own and they inspired the medieval imagination.
Spurred on the age of discovery in the 145th and 16th centuries, when famous explorers like Columbus and Da Gama and Magellan left Europe in their ships, they weren't looking for a new world; they were looking for spices.
And we know what important historical repercussions some of those voyages had. "
L18L4
"Listen to part of lecture in biology class.Well, it's finally looking like spring is arriving.
The last of the winter snow would be melting away in a few days.
So before we close today, I thought I'd mention a biological event that's a part of the transition from winter to spring.
Something you can go outside to watch if you have some patience.
There is a small creature that lives in this area, you have probably seen it.
It's the North American wood frog.
Now the Wood frog's not that easy to spot since it stays pretty close to the ground, under leaves and things, and it blends in really well with its background as you can see.
But they are worth the effort because they do something very unusual, something you might not have even thought possible.
OK, Northern American wood frogs live over a very broad territory or range.
They are found all over the Northeastern United States and all through Canada and Alaska, even inside the Arctic Circle.
No other frog is able to live that far and the North.
But wherever they live, once the weather starts to turn cold and the temperature starts to drop below freezing, as soon as the frog even touches an ice crystal or a bit of frozen ground, well, it begins to freeze.
Yes，Jimmy, you look a little bit taken aback.
Wait. You mean it's still alive but it freezes, solid?
Well, almost. Ice forms in all the spaces outside cells but never within a cell.
But... then how does its heart beat?
It doesn't.
But then... how could it... how could it do such a thing?
Well, that first touch of ice apparently triggers a biological response inside the frog.
That first of all starts drawing water away from the center of its body, so the middle part of the frog, its internal organs, its heart, lungs, livers, these start getting drier and drier while the water that's being pulled away is forming a puddle around the organs just underneath the skin.
And then that puddle of water starts to freeze.
OK, up to now, the frog's heart is still beating, right?
Slower and slower, but... and in those last few hours before it freezes, it distributes glucose, a blood sugar throughout its body, its circulatory system, sort of acts like an antifreeze.
A solution of antifreeze like you put your car in the winter?
Well, you tell me.
In frogs, the extra glucose makes it harder for the water inside the cells to freeze.
So the cells stay just slightly wet, enough so that they can survive the winter.
Then, after that, the heart stops beating altogether.
So, is that the same?
Yeah, I don't really know, but how long does it stay that way?
Well, it could be days or even months, all winter in fact, but, see, the heart really doesn't need to do any pumping now because the blood is frozen too.
I just, I guess I just don't see how it isn't, you know, clinically dead.
Well, that's the amazing thing and how it revives is pretty amazing too.
After months without heartbeat, spring time comes around again, the earth starts to warm up, and suddenly one day, ping, a pulse, followed by another one, then another until maybe ten, twelve hours later, the animal is fully recovered.
And does the thawing process have some kind of trigger as well?
Well, we are not sure actually, the peculiar thing is even though the sun is warming the frog up on the outside, its inside thaw out first, the heart and brain and everything.
But somehow it all that just happens that way every spring.
And after they thaw does it affect them like their lifespan?
Well, hmm, we really don't know a lot about how long a wood frog normally lives, probably just a few years, but there is no evidence that the freezing process affects its longevity.
It does have some other impacts though.
In studies, we found that when it comes to reproduction, freezing diminishes the mating performance of males.
After they've been frozen and thawed of course, they don't seem quite as vocal.
They move slower and they seem to have a harder time recognizing a potential mate.
So if the male frog could manage not to go through this freezing cycle, he'd probably have more success in mating. "
L19C1
"Listen to a conversation between a student and the professor.Hi, professor Handerson. That was a really interesting lecture in class today.
Thanks, Tom. Yeah, animals' use of deception, ways they play tricks on other animals, that's a fascinating area.
One we are really just starting to understand.
Yeah, you know, selective adaptations over time are one thing.
Oh, like, non-poisonous butterflies, that have come to look like poisonous ones.
But the idea that animals of the same species intentionally deceive each other, I have never heard that before.
Right, like, there are male frogs who lower their voices and end up sounding bigger than they really are.
So they do that to keep other frogs from invading their territory?
Right, bigger frogs have deeper voices, so if a smaller frog can imitate that deep voice. Well...
Yeah, I can see how that might do the trick.
But, anyway, what I wanted to ask was, when you started talking about game theory, well, I know a little bit about it, but I am not clear about its use in biology.
Yeah, it is fairly new to biology.
Basically, it uses math to predict what an individual would do under certain circumstances.
But for example, a buisness sells, oh computer, say, and they want to sell their computers to a big university.
But there is another company bidding too.
So, what should they do?
Well, try to offer the lowest price so they can compete, but still make money.
Right, they are competing, like a game, like the frogs.
There are risks with pricing too high, the other company might get the sale, there is also the number and types of computers to consider.
Each company has to find a balance between the costs and benefits.
Well, game theory creates mathematical models that analyze different conditions like this to predict outcomes.
Ok, I get that.
But how does it apply to animals?
Well, you know, if you are interested in this topic, it would be perfect for your term paper.
The literature review?
Yeah, find three journal articles about this or another topic that interests you and discuss them.
If there is a conflict in the conclusions or something, that would be important to discuss.
Well, from what I have looked at dealing with game theory, I can't say I understand much of the statistics end.
Well, I can point you to some that presents fairly basic studies, that don't assume much background knowledge.
You'll just need to answer a few specific questions: what was the researchers' hypothesis? What did they want to find out?
And how did they conduct their research? And then the conclusions they came to?
Learning to interpret these statistics will come later. "
L19L1
"Listen to part of a lecture in a linguistics class.All right, so far we have been looking at some of the core areas of linguistics, like syntax, phonology, semantics, and these are things that we can study by looking at one language at a time, how sounds, and words, and sentences work in a given language.
But the branch of historical linguistics, involves the comparison of several different languages, or the comparison of different stages of a single language.
Now, if you are comparing different languages, and you notice that they have a lot in common.
Maybe they have similar sounds and words that correspond to one another that have the same meaning and that sound similar.
Let's use a real-world example.
In the 18th century, scholars who have studied the ancient languages, Sanskrit, Latin and Greek, noticed that these three languages had many similarities.
And there might be several reasons why languages such as these had so much in common.
Maybe it happened by chance, maybe one language was heavily influenced by borrowed words from the other.
Or maybe, maybe the languages developed from the same source language long ago, that is, maybe they are genetically related, that was what happened with Sanskrit, Latin and Greek.
These languages had so many similarities that it was concluded that they must have all come from the same source.
And talk about important discoveries in linguistics, this was certainly one of them.
The scholars referred to that source language as Proto-Indo-European.
Proto-Indo-European is a reconstructed language.
Meaning, it is what linguists concluded a parent language of Sanskrit, Latin and Greek would have to be like.
And Proto-Indo-European branched out into other languages, which evolved into others.
So in the end, many languages spoken all over the world today can trace their ancestry back to one language, Proto-Indo-European, which was spoken several thousand years ago.
Now, one way of representing the evolution of languages, showing the way languages are related to each other, is with the family tree model.
Like a family tree that you might use to trace back through generations of ancestors, only it's showing a family of genetically related languages instead of people.
A tree model for a language family starts with one language, which we call a mother language, for example, Proto-Indo-European.
The mother language, is the line on the top of this diagram, over time, it branches off into new daughter languages, which branch into daughter languages of their own, and languages that have the same source, the same mother, are called sisters.
They share a lot of characteristics, and this went on until we are looking at a big upside down tree languages like this.
It is incomplete of course, just to give you an idea.
So that's the family tree model, basically.
Now, the tree model is a convenient way of representing the development of a language family and of showing how closely related two or more languages are.
But it is obviously very simplified.
Having a whole language represented by just one branch on a tree doesn't really do justice to all the variations within that language.
You know, Spanish that spoken in Spain isn't exactly the same as Spanish that is spoken in Mexico, for example.
Another issue is that languages evolve very gradually, but the tree model makes it look like they evolve over night, like there was a distinct moment in time when a mother language clearly broke off into daughter languages.
But it seems to me it probably wasn't quite like that. "
L19L2
"Listen to part of a lecture in an astronomy class.So how many of you have seen the Milky Way, the Milky Way galaxy in the sky?
You? You have?
You? You have?
Yeah, I was camping, and there was no Moon that night, it was super dark.
Um anybody else? Um...not too many.
Isn't that strange that the Milky Way is the galaxy that the planet Earth is in, and most of us have never seen it?
Now, what's the problem here.
Light pollution, right? From street lights and stuff.
Yes, especially unshielded street lights, you know, ones that aren't pointed downward.
Now, here is an irony, the building we are in now, the astronomy building not far from our observatory has unshielded lights.
So the problem is pretty widespread.
It's basically beyond control, as far as expecting to view the night sky anywhere near city, I mean.
Um, I've live around here my whole life, and I 've never seen that Milky Way within city limits, and I probably never will.
There is a price for progress, uh?
But let's think beyond light pollution.
That's only one kind of a technological advance that interfered with the astronomical research.
Can anyone think of another?
No, OK. Let's look at it this way.
We don't only gain information by looking at the stars.
For the past seventy years or so, we've also used radio astronomy, which lets us study radio waves from the sky.
How can you observe radio waves, I mean tell anything about the stars from that.
Well, in optical astronomy, using a telescope and observing the stars that way,
we rely on visible light waves. What we are seeing from Earth is actually electromagnetic radiation that's coming from stars, and just one part of it is visible light.
But there are problems with that.
When photons and light waves hit objects in our atmosphere, water droplets oxygen and nitrogen molecules, dust particles and so on, these objects are illuminated, they are lit up, and those things are also being lit by all our street lights, by the Moon, all these ambient light.
And on top of that, when that visible radiation bounces off those molecules, it scatters in all directions.
And well, lights from stars, even nearby in our own galaxy, doesn't stand a chance against that.
Basically, the light bouncing off all these objects close to Earth is brighter than what's coming from the stars.
Now, radio waves are electromagnetic radiation that we can't see.
Nearly all astronomical objects in space emit radio waves, whether nearby stars, objects in far away galaxies, they all give off radio waves.
And unlike visible light waves, these radio waves can get through the various gases and dust in space, and through our own Earth's atmosphere comparatively easily.
Ok, then we might as well give up on optical astronomy and go with radio astronomy.
Well, the thing is, with a radio astronomy, you can't just set up a telescope in your backyard and observe stars.
One problem is that radio waves from these far away objects, even though they can get through, are extremely faint.
So we need to use radio telescopes, specially designed to receive these waves.
And then, well, we can use computers to create pictures based on the information we receive.
That sounds cool, so how do they do that?
Well, it's kind of like the same way a satellite dish receives its signal, if you are familiar with that.
But radio telescopes are sometimes grouped together, is the same effect as having one really big telescope to increase radio wave gathering power.
And they use electronics, quite sophisticated.
Yeah, it's neat how they do it, but for now, why don't we just stick with what we can learn from it.
Em, some very important discoveries have been made by this technology, especially you consider that some objects in space give off radio waves but don't emit any light.
We have trouble discovering those sorts of bodies as much as studying them using just optical telescopes.
Well, if the radio waves are so good at getting through the universe, what's the problem?
Well, answer this, how come people have to turn off their cell phones and all our electronic devices when an air plane is about to take off?
The phones interfere with the radio communication at the airport, right?
Oh, so our radio waves here, on Earth interfere with the waves from space?
Yes, signal from radios, cell phones, TV stations, remote controls, you name it, all these things cause interference.
We don't think about that as often as we think about light pollution.
But all those electrical gadgets pollute the skies, just in a different way. "
L19C2
"Listen to a conversation between a student and the director of the student cafeteria.Hi, I... I am sorry to interrupt, could I ask you a few questions?
Sure, but if it is about your meal plan, you'll need to go to Room 45, just down the hall.
Eh, no, I am OK with my meal plan.
I am actually here about the food in the student cafeteria.
Oh, we do feed a lot of students, so we can't always honor individual requests, I am sure you understand.
Of course. It is just that I am a little concerned, I mean, a lot of us are, that a lot of the food you serve isn't really that healthy.
Like there are so many deep-fried foods.
As a matter of fact, we recently changed the type of oil we use in our fryer. It is the healthiest available.
And would you believe that at least ten students have already complaint that their french fries and fried chicken don't taste as good since we switched?
Oh, I try not to eat too many fried foods anyway.
I am just aware that, eh... You see, I used to work in a natural food store.
They had all these literature advising people to eat fresh organic growing food.
Working there really open my eyes.
Did you come to the organic food festival we had last year to celebrate Earth Day?
Oh, sorry, I must have missed that.
We served only certified organic food, most of which was from local farms.
It is not something we can afford to do on a daily basis, and there aren't too many organic farms around here.
But sometime the produce we offer is organically grown.
It depends on the season and the prices of course.
That's good to know. I like the fact that organic farms don't use chemical pesticides or anything that can pollute the soil or the water.
I do too. But let me ask you this.
Is it better for the environment to buy locally grown produce that is not certified as organic or is it better to get organically grown fruits and vegetables that must be trucked in from California, three thousand miles away.
What about fossil fuels burned by the trucks' engine.
Plus the expense of shipping food across long distances.
And nutritionally speaking, an apple is an apple however it is grown.
I see your point. It is not so clear-cut.
Why don't you visit our cafeteria's website?
We list all our food suppliers. You know, where we buy the food that we serve.
And the site also suggests ways to make your overall diet a healthy one.
You can also find some charts listing fat and calorie content for different types of seafood, meat and the other major food groups.
I didn't realize you thought about all these things so carefully, I just noticed the high-calorie food in the cafeteria.
Well, we have to give choices so everyone is satisfied.
But if you wish to pursue this further, I suggest that you talk to my boss.
That's OK, seems like you are doing what you can. "
L19L3
"Listen to part of a lecture in a marine biology class.Ok, today we are going to continue our discussion of plant life in coastal salt marshes of North America.
Salt marshes are among the least inviting environments for plants.
The water is salty, there is little shade and the ocean tide comes in and out, constantly flooding the marsh, so the variety of plants found in salt marshes is limited, but there is a plant genus that thrives there, the Spartina.
In fact, the Spartina genus is the dominant plant found in salt marshes.
You can find one type of the Spartina, Saltmarsh Cordgrass, growing in low marsh areas.
In higher marsh areas, you are likely to find a Spartina commonly called Salt-meadow Hay.
So how is the Spartina able to survive in an environment that would kill most plants?
Well, it is because salt marsh grasses have found ways to adapt to the conditions there.
First of all, they are able to withstand highly saline conditions.
One really interesting adaptation is the ability to reverse the process of osmosis.
Typically, the process of osmosis works.
Well, when water moves through the wall of a plant cell, it will move from the side containing water with the lowest amount of salt into the side containing the highest amount of salt.
So imagine what would happen if a typical plant suddenly found itself in salt water, the water contained in the plant cells, that is water with very little salt would be drawn out toward the seawater, water with a lot of salt.
So you can see the fresh water contained in the plant will be removed and the plant will quickly lose all its water and dehydrate.
But what about the Spartinas.
Well, they allow a certain amount of salt to enter their cells, bringing the salt content of the water within the plant, to a slightly higher concentration than that of the surrounding seawater.
So instead of fresh water moving out of the plant cells, salt from the seawater enters, reverse osmosis, and this actually strengthens the cells.
Another adaptation to the salty environment is the ability to excrete excess salt back into the environment.
That's why you might see a Spartina shimmering in the sunlight.
What's reflecting the light is not salt from seawater that has evaporated, although that's a good guess.
But it is actually the salt that came from within the plant.
Pretty cool, eh?
You can really impress your friends and family with that little titbit the next time you are in a salt marsh.
But coping with salt is not the only challenge for plants in the salt marsh.
Soil there is dense and very low in oxygen, so Spartinas have air tubes.
Air enters through tiny openings on the leaves, the tubes provide direct pipe line for oxygen, carrying it down the leaves through the stems and into the roots, where it is needed.
If you pull up a Spartina, you might even notice some reddish mud on some of the roots, this is caused by oxygen reacting with iron sulfide in the soil, and it produces iron oxide or rust.
Now, although the Spartinas have adapted several chemical and physical mechanisms that allow them to thrive in salt water and to feed oxygen to their roots.
There is yet another aspect of the harsh environment that they have to adapt to, the force of tides and occasional violent storms.
Wind and water are constantly crashing into these plants.
So as you might have guessed, they have developed a means of solidly anchoring themselves into the soil.
How? Well, They have tough sort of underground stems called rhizome.
Rhizomes from one plant grow through the muddy soil and interlock with those of other nearby plants.
The plants form a kind of colony, a community that will survive and perish together.
Because alone as single plants, they cannot survive.
Of course the plants in these colonies also need tough resilient stems above the soil, stems that can bent a lot but not break as water constantly crashes into them.
So in addition to the interlocking underground rhizomes, they have yet another adaptation, and it's... well, we are back to reverse osmosis again.
By adjusting the osmotic pressure so that the cells are always fully inflated, the plant is able to withstand great pressure before snapping.
So Spartinas may look like simple marsh grass, but they are really a wonder of chemistry, physics and structural engineering that allows them to survive and even thrive in an environment in which most plants will wilt and die within hours. "
L19L4
"Listen to part of a discussion in an art history class.All right, let's continue our discussion of portrait artists and portraiture.
Who remembers any of the important points we made last time? Sandra?
Um, well, artists have done portraits of people for centuries, of famous people and regular people, and most portraits convey the artists' personal vision, like their feelings and insights about a person.
Great, that's a crucial point, and I'd like to explore that a little today.
A great example of that, that vision in portraiture, is Cecilia Beaux.
Cecilia Beaux was born in 1855, and after learning to paint and studying with several important artists of the time, Beaux became known as one of the best portrait painters in the United States.
She was very successful. She even had portraits of the wife and children of Theodore Roosevelt, while he was president.
Some did not get much more prestige than that.
Now, those portraits also reflect the kind of subjects that Beaux tended to use, which were mostly women and children.
For example, in her first major work, her subjects were ... the painting featured her sister and her nephew.
Yes, Mark?
Yeah, it just seems interesting.
I was wondering if that was unusual to have a portrait artist who is a woman become so well-known and successful in the 19th century.
Great question. Yeah, she really stood out back in the 1800s.
And today, she is still considered one of the greatest portrait painters of her time, male or female.
In fact, she was the first full-time female instructor at the Pennsylvania Academy of the Fine Arts.
And she was a full member of the National Academy of Design.
These are pretty important institutions, so, yeah, she definitely made headway for women artists.
Ok, so let's look at one of her portraits now.
This painting is called The Dreamer. It is one of my favorites.
And I think it is especially characteristic of Beaux's work.
So what you see here is a portrait of a close friend of Cecilia Beaux.
So tell me what's the first thing that draws you to this painting? What catches your eye first.
Well, for me, it is her face and hands, I think they are really expressive.
And also, they make the woman seem very contemplative, seems like she is thinking pretty seriously about something.
Yeah, her eyes kind of draw you in.
But what strikes me is the contrasting colors, the white dress and the dark background.
It kind of reminds me of that painting we discussed a few weeks ago, by ...eh... John Singer Sargent.
I think it was called Madame X?
I agree, good point.
Yes, Beaux had high regard for Sargent's work.
And this is something, a technique that you will find in both of their work.
Ok, but the painting is called The Dreamer.
What do you see is dreamlike about it?
Well, the background behind the woman is pretty vague.
Like, maybe there is no real context, like no definite surroundings, expecially compared to the woman herself, since she is so clear and well-defined.
Yes, the unclear background definitely contributes to that dreaminess.
It is meant to show a sense of isolation I think.
With the woman is deep in a daydream and not really aware of anything else.
This painting shows how insightful Cecilia Beaux was as a portrait artist.
Besides her excellent technical skills, like her use of brush strokes and color to make an impression, both perspectives come through.
Her portraits reveal her own interpretation of her subject's state of mind.
This is what it is all about, not just likenesses.
Now, the undefined background also shows how Cecilia Beaux was influenced by the French Impressionists, who believed, like Beaux, in a personal rather than conventional approach to their subject matter.
Beaux used some impressionist techniques and share much of their philosophy, but her style, it was all her own. "
L20C1
"Listen to a conversation between a student and a library employee.Excuse me, I received a letter that I am supposed to return a book that I checked out back in September, it's called Modern Social Problems.
But I am writing my senior thesis, so I thought I was allowed to keep the book for the whole academic year.
So you signed up for extended borrowing privileges?
Yeah.
And we are still asking you to bring the book back?
Uh-huh. Do I really have to?
Well, let me check the computer. The title was... Modern Social Problems?
Yeah.
Eh... Ok, yeah. It's been recalled.
You can keep it all year as long as no one else requests it, but someone else has, it looks like one of the professors in the sociology department.
So you have to bring it back.
You can check it out again when it is returned in a couple of weeks.
What if the person renews it?
And I really need it right now.
All of it? Or is there a certain section or chapter you are working with?
Well, there's one chapter in particular I am working with, but why?
Well, we normally don't do this, but because of the circumstances we can photocopy up to one chapter of the book for you.
Why don't you do that for the one you are working with right now?
And by the time you need the rest of the book, maybe it'll have been returned.
Oh, that would be great.
Do you have it with you?
Eh... no, it's in my dorm room.
These are books I want to check out today.
Is it OK if I bring that one by in a couple of days?
Actually, the due day is tomorrow.
After that, there'll be a two dollar per day fine.
But you need to return it today if you want to check out any books today.
That's our policy.
Oh, I see.
Yeah, not a lot of people realize that.
In fact, every semester we get a few students who would have their borrowing privileges suspended completely because they haven't returned books.
They are allowed to use books only in the library. They are not allowed to check anything out because of unreturned books.
That's not good. I guess I should head back to the dorm right now.
But before you go, what you should do is fill out a form requesting the book back in two weeks.
Then the person who requested it won't be able to renew it. You'll get it back quickly.
I'll do that right now. "
L20L1
"Listen to part of a lecture in a linguistics class.Ok, the conventions or assumptions that govern conversation, these may vary from one culture to another, but basically, for people to communicate, there is a ... they have to follow certain rules.
Like if I am talking with you and I start saying things that are not true, if you can't tell when I am lying and when I am telling the truth, well, we are not going to have a very satisfactory conversation, are we?
Why? Because it violates one of the Gricean Maxims.
that's a set of rules or maxims a philosopher name H.P.Grice came up with in 1970s.
One of these Gricean Maxims is... well, I've already given you a hint.
Oh, you just can't go around telling lies.
Right, or as Grice put it, ""Do not say what you believe to be false.""
That's one of Grice's Maxims of Quality as he called it.
So that's pretty obvious.
But there are others just as important, like, eh... suppose you would ask me what time it was and I replied ""my sister just got married"", what would you think?
You are not really answering my question.
No, I am not, am I? There is no connection at all, which feels wrong because you generally expect to find one.
So one important maxim is simply: be relevant.
And using the so-called Maxim of Relevance we can infer things as well, or rather the speaker can imply things and the listener can make inferences.
For instance, suppose you say you would really love to have a cup of coffee right now, and I say ""there's a shop around the corner"".
Now, what can you infer from what I said?
Well, the shop sells coffee for one thing.
Right, and that I believe it is open now.
Because if I weren't implying those things, my response would not be relevant.
It'd have no connection with what you said before.
But according to the maxim, my response should be relevant to your statement, meaning, we should assume some connection between the statement and the response.
And this maxim of relevance is quite efficient to use.
Even if I don't spell out all the details, you can still make some useful logical inferences, namely, the shop is open and it sells coffee.
If we actually have to explain all these details, conversations would move along pretty slowly, wouldn't they?
OK, then there's the maxims of manner, including things like be clear, and avoid ambiguity.
And another more interesting maxims is one of the so-called maxims of quantity, quantities of information, that is.
It says, to give as much information as is required in the situation.
So suppose you asked me what I did yesterday and I say ""I went to the Art Museum.""
You would likely infer that I saw some works of art.
Suppose, though, that I did not go inside the museum, I just walked up to it then left.
Then I violated the quantity maxim by not giving enough information.
So you can see how important implications are to our ability to carry on a conversation.
But there are times when people will violate these maxims on purpose.
Let's say a boss is asked to write a letter of recommendation for a former employee seeking an engineering job.
The letter he writes is quite brief.
Something like, uh, Mr . X is polite and always dresses quite neatly.
So what does this really mean?
Oh, I see.
By not mentioning any important qualities related to the job, the boss is ... like, implying that this is best that can be said about Mr . X that he is really not qualified.
Exactly. It's a written letter not a conversation, but the principle is the same.
The boss is conveying a negative impression of Mr. X without actually saying anything negative about him.
So, by violating the maxims, we ...eh... but ... it can be a way to be subtle or polite, or to convey humor through sarcasm or irony.
Sometimes though people will violate maxims for another purpose: to deceive.
Now, can you imagine who might do such a thing?
Some politicians.
Or advertisers.
Right. Anyone who may see an advantage in implying certain things that are untrue without explicitly saying something untrue.
They think, hey, don't blame us if our audience happens to draw inferences that are simply not true.
So next time you see an advertisement saying some product could be up to 20% more effective, think of these maxims of quantity and relevance, and ask yourself what inferences you are being led to draw.
Think, more effective than what exactly?
And why do they use those little phrases ""could be"" and ""up to""?
These claims give us a lot less information than they seem to. "
L20L2
"Listen to part of a lecture in an environmental science class.Let's take you back about 11000 years ago when Earth entered the latest interglacial period.
Interglacial periods are, typically periods of time between Ice Ages, when the climate warms, and the glacial ice retreats for a time, before things cool off again and another Ice Age begins.
And for over the past several million years, Earth's sort of default climate has actually been Ice Age, but we have experienced periodic regular thaws, and the last one, the one we are in now, started about 11000 years ago.
Now the typical pattern for an interglacial period, and we have studied several, is that the concentration of carbon dioxide and methane gas, actually reaches is... its peak, that is, there is the most carbon dioxide and methane gas, uh, greenhouse gases in the atmosphere just after the beginning of the interglacial period.
And then, for reasons which are not entirely clear, the concentration of greenhouse gases gradually goes down.
Now the climate continues to warm for a while because there is a lag effect.
But uh, gradually, as the concentration of the greenhouse gases goes down, Earth starts to cool again, and eventually you slip back into an Ice Age.
Um, however, for the latest interglacial period, the one we are in now, this pattern did not hold, that is, the concentration of carbon dioxide and methane dipped a little bit after, uh, uh, after peaking at the beginning, near the beginning of the interglacial period, but then it began to rise again.
Um, what was different about this interglacial period than the other ones?
Well, one of the big differences is human activity.
People began to raise crops and animals for food instead of hunting for them.
This is the agricultural revolution.
And it began to happen in the earliest stages about 11000 years ago.
Now scientists have tended to regard... the.. uh... agriculture revolution as a beneficiary of the... uh... fortuitous shift in climate.
However, some new theories of climate, new theorists of climate have proposed that perhaps humanity was having an effect on the climate as far back as the beginnings of the agricultural revolution.
When you grow crops and uh, pasture your animals, one of the things you do is you cut down the forests.
If you cut down the forests when you burn the trees for fuel and don't replace them with other trees, or when you just leave them to rot and don't allow other trees to grow, you end up with a lot more carbon in the forms of carbon dioxide getting into atmosphere.
Um, another gas associated with the spread of agriculture is methane.
Methane forms in large concentration above wetlands, and as it turns out, the cultivation of certain grains creates vast areas of artificial wetlands, and probably drastically increases the amount of methane getting into the atmosphere, over and above what would be there.
So, um... agriculture, the spread of agriculture, you know we are talking over thousands of years, um... but this could very well had a profound effect on the composition of Earth's atmosphere.
It is kind of ironic to think that absent of that effect, it maybe that we would be heading into an Ice Age again.
In fact, back to 1970s, a lot of theories were predicting that, you know, the climate would start to cool and we'd slowly enter into the new Ice Age.
And then they were puzzled as to why it didn't seem to be happening.
Um... now what are the implications for the future?
Well, it is a little tricky.
I mean, you could say, well, here is an example of... um... human activity, the agriculture revolution which actually was beneficial; we altered the climate for the better, perhaps, by preventing an Ice Age.
But then industrialization, of course, has drastically increased the amount of carbon dioxide that humans are putting into the atmosphere, the burning of fossil fuels tends to put a lot of CO2 into the atmosphere.
Um, so we are entering into uncharted territory now, in terms of the amount of carbon dioxide, the concentrations of carbon dioxide that are now being put into the atmosphere as a result of industrialization and the use of fossil fuels. "
L20C2
"Listen to a conversation between a student and a professor.Professor Jennings, I hope I am not interrupting, but you wanted to see me?
Oh, hello, Suzane. Yes, yes, come right in.
How are you doing?
All right.
Well, good. The reason I wanted to talk to you was that while you were presenting you linguistics project in class the other day, well, you know, I was thinking you are a perfect candidate for the dean's undergraduate research fund.
Um... Professor, I am not really sure what the... um... dean...
Undergraduate research fund is...
It is a mouthful I suppose.
OK. Here's the thing.
Every year the school has a pool of money to fund a number of research projects of undergraduate students.
Because as you can imagine, indepth research often requires monetary support.
I would like to expand on my research.
Good. First a panel of professors reviews the applications for the grant.
And then they decide which research project should be funded.
The allotted money could be used for travel expenses, to attend a conference for example, or for things like supplies, research equipment, resources that are necessary to conduct the research.
I see.
Right. And I think you should apply for this grant.
Your project is definitely eligible.
And you can expand it if you have the necessary resources.
So, does it sound like something you would be interested in?
Oh, yeah, sounds great. I thought the topic I work on was very interesting, and it is certainly relevant to my linguistics major.
I assume it will also look good when I try to get into graduate school. But how do I apply for the grant?
It is pretty straightforward.
A brief description of your proposed project, and an estimated budget.
How much you need to spend and what you intend to spend it on.
Also a glowing letter of recommendation from a linguistics professor wouldn't hurt, which I'd be more than happy to write up for you.
OK. Cool.
I am pretty clear on how to carry out my project, but I am not sure where I can find more information on the subject.
Well, I have already thought of that.
There's this private library at a university in Boston.
By the way, because I graduated from that school, I can get you access to it, no problem.
You see, the library houses lots of unpublished documents that are relevant to your topic.
So I can put that in the application for the grant, that I plan on using material from that library for my research and figure a trip to Boston into my budget?
Exactly. I really think judging from your work in class, and the relevance and clarity of this project, you really have a good chance of getting the funding.
OK. I'll definitely apply then.
The sooner the better.
It is due in a few weeks.
Good Luck! And I'll get that letter written up right away. "
L20L3
"Listen to part of a lecture in a literature class.All right, so now we've talked about folk legends and seen that their... one of their key features is there's usually some real history behind them.
They are often about real people, so you can identify with the characters, and that's what engages us in them.
The particular stories might not be true and some of the characters or events might be made up.
But there's still a sense that the story could have been true since it is about a real person.
That's distinct contrast from the other main branch of popular storytelling, which is folk tales.
Folk tales are imaginative stories that... um... like folk legends, they have been passed down orally, from storyteller to storyteller for... since ancient times.
But with folk tales you don't ever really get the sense that the story might have been true.
They are purely imaginative and so quite revealing, I think anyway, about the culture and the connection between folk tales and culture, which we'll talk about.
But first let's go over the various types of folk tale and focus specifically on Norwegian folk tales since they illustrate the variety pretty well.
There are in general three main types of Norwegian folk tales.
One is animal stories, where animals are the main characters.
They can be wild animals or domestic, and a lot of times they can talk and behave like humans, but at the same time, they retain their animal characteristics too.
They tend to involve animals like bears, wolves and foxes.
The point of these stories, their, their internal objectives, so to speak, is usually to explain some feature of the animal, how it arose.
So there's one about a fox who fools a bear into going ice fishing with his tail.
When the bear puts his tail into the water through a hole in the ice, to try and catch a fish, the ice freezes around it, and he ends up pulling his tail off.
So that's why bears to this day have such short tails.
The second category of Norwegian folk tale is the supernatural.
Eh... stories about giants and dragons and trolls, and humans with supernatural powers or gifts, like invisibility cloaks.
Or where people are turned into animals and back again into a person, those are called transformation stories.
There's a well-known Norwegian supernatural folk tale, a transformation story called East of the Sun and West of the Moon, which we'll read.
It involves a prince who is a white bear by night and a human by day.
And he lives in the castle that's east of the Sun and west of the Moon, which the heroine in the story has to try to find.
Besides being a good example of a transformation story, this one also has a lot of the common things that tend to show up in folk tales.
You will find the standard opening, ""once upon a time"".
And it has stock characters like a prince, and a poor but beautiful peasant girl, she is the heroine I mentioned.
And... um... it has a very conventional form.
So no more than two characters are involved in any one scene.
And it has a happy ending.
And it's... the story is presented as though... well, even though a lot of the actions that occurred are pretty fantastic, so you'd never think of it as realistic.
The characters still act like... they resemble real people.
They are not real or even based on historical figures.
But you might have a supernatural story involving a king, and he'd act like you'd expect a Norwegian king to act.
OK. The third main kind of folk tale is the comical story.
We'll say more later about these, but for now, just be aware of the category and that they can contain supernatural aspects, but they are usually more playful and amusing overall than supernatural stories.
Now, as I said, traditionally, folk tales were just passed down orally.
Each generation of storytellers had their own style of telling a story.
But... um... in Norway, before the 19th century, folk tales were just for kids.
They weren't seen as worthy of analysis or academic attention.
But this changed when the romantic movement spread throughout Europe in the mid-19th century.
Romantics looked at folk tales as sort of a reflection of the soul of the people.
So there was something distinctly Norwegian in folk tales from Norway.
And there was renewed pride in the literature and art forms of individual countries.
As a result, the first collection of Norwegian folk tales is published in 1852.
And there have been many new editions published since then.
For the people of Norway, these stories are now an important part of what it means to be Norwegian. "
L20L4
"Listen to part of a lecture in a biology class.Now, James, you said you had been to the State of Maine, right?
Yeah, actually I lived in western Maine until I was about sixteen.
Great. So why don't you tell everybody what is like there in the winter?
The winter? Well, it's cold. And there's lots of snow, you wouldn't believe how much snow we used to get.
Actually I would. I did field research up there a couple of winters.
And it really is an incredible environment.
And to survive in that sort of environment, animals have to adapt, to evolve in response to their surroundings.
As you recall, an adaptation is any feature, um... physical or behavioral feature of a species that helps it survive and reproduce.
And in adapting to extreme climates, like Maine in the winter time, animals can evolve in pretty interesting ways.
Take, for example, the snowshoe hare.
Ok, the snowshoe hare, and of course, that's H-A-R-E, like a rabbit.
Although I probably should mention that technically a hare is not exactly the same as a rabbit, even though it is very similar.
The primary difference is that a rabbit's young are born blind and without fur, while a hare's babies are born with a full coat and able to see.
Now, the snowshoe hare, tell me, what sort of adaptations do you think it has developed that help it survive the Maine winters?
I'll give you a hint.
Food isn't an issue.
The hare actually has abundant food in the small twigs it finds.
Well, I don't know. I mean, I know we used to try to look for these rabbits, eh... hares, when we went hiking in the winter, but it was often hard to find them in the snow.
Yes. That's exactly right.
The major concern of the snowshoe hare in the winter is predators.
And now that includes humans.
So one of its adaptations is basically camouflage.
In other words, its coat, its fur, turns from brown in the summer to white in the winter, which makes it harder for the hare's predators to see it against the white snow.
Yeah, but I could swear I remembered seeing rabbits in the snow a couple of times, I mean hares, that were brown.
Well, you may very well have.
Timing is really important, but the snowshoe hare doesn't always get it exactly right.
Its chances for survival are best if it turns white about the time of the first snowfall.
And it's the amount of daylight that triggers the changing of the hare's coat.
As the days get shorter, that is, as the Sun is up for a shorter and shorter time each day, the snowshoe hare starts growing white fur and shedding its brown fur.
The hare does a pretty good job with its timing, but sometimes when there's a really early or late snow, it stands out.
Plus, it takes about a month for the snowshoe hare's coat to completely change color.
So if there's a particularly early snowfall, it's very likely that the hare's fur would not yet be totally white.
And that would make this a particularly dangerous time for the hare.
OK. What else? Other adaptations? Susan?
Well, it's called the snowshoe hare, so are its feet somehow protect it from the cold?
Well, this animal's name does have to do with an adaptation of its feet.
Uh... though, not like it has warm furry boots or something to keep its feet from getting cold.
You've probably never needed to wear snowshoes.
But, well, snowshoes are not like thick furry shoes designed to keep the feet warm, they are actually quite thin, but very wide.
What they do is spread out the weight of the foot coming down on the snow.
See, the problem with walking on snow is that you sink in with every step.
But with snowshoes, you don't sink in, you walk on top of the snow.
It makes walking through the Maine countryside in the winter much easier.
Anyway, the snowshoe hare has an adaptation that plays on the same idea.
It has hind feet that act like snowshoes.
I mean, it's paws are wide and they allow the hare to hop and run just at the surface of deep snow.
And this is a huge advantage for the snowshoe hare since by contrast, the feet of its predators usually sink right down into the snow.
Now, another advantage related to this is that unlike many animals in winter, snowshoe hares can stay lean and light weight.
They accumulate essentially no body fat.
Can anyone guess why this is so?
They don't eat very much?
Well, yes. But not because there isn't enough food around.
It's because, like I said, food is almost always within reach,
And they don't have to store up a lot of food energy for the harsh winters. "
L21C1
"Listen to a conversation between a student and a professor.Excuse me, can I help you?
You look a little lost. Yeah, I am. This is my first day on campus, and I don't know where anything is.
Can't find your orientation session?
Uh-huh. What a way to begin!
Lost going to orientation.
Well, my guess is in the auditorium, that's where they usually are.
You're right, the general ones.
I went to one of those sessions earlier today.
But now I need the one for my major, engineering.
My schedule says the meeting room is in... Johnson Hall?
In the engineering department, which should be right here in front of us, according to the map.
But this building is called the Morgan Hall.
Well, your map reading skills are fine actually.
This used to be Johnson Hall, all right.
Trouble is they changed the name to Morgan Hall last spring.
So they sent you a map with an old name? I am surprised.
Well, this was actually mailed out month and month ago.
I got a second pack in the mail more recently with another one of these maps in it.
I guess they must have the updated name.
I left that one in my dorm room.
Well, things change fast around here.
This building was renamed after one of our professors.
She retired a few months ago.
She is very well-known in the world of physics.
Too bad for Johnson, I guess.
Who is Johnson anyway?
Oh, one of the early professors here.
Unfortunately, I guess his ideas are going out of style.
Science kept marching forward.
I'll say it does. That's why I transferred to this university.
I was really impressed with all the research equipment you guys have at the laboratories.
You are really on the forefront.
Um... so do you know what kind of engineering you want to specialize in?
Yeah, aerospace engineering.
Well, the aerospace engineering department here is excellent!
Eh... do you know that this university was the first one in the country to offer a program in aerospace engineering?
Yeah, I know. And a couple of students who graduated from here became astronauts and orbited the Earth.
Right. The department has many prominent alumni.
Well, you might end up taking some of your advanced math course with me.
I get a lot of students from the engineering department because I teach the required applied mathematics courses.
Oh, cool. Actually, I want to get a minor in math.
Excellent. Hmm... A major in aerospace engineering with a minor in math, you'll go far with that degree.
More of our students should do that.
There are so many more opportunities available in the field when you have a strong math background.
I'm glad to hear you say that. "
L21L1
"Listen to part of a lecture in a history of science class.Ok, we have been talking about how throughout history, it was often difficult for people to give up ideas which have long been taken for granted as scientific truth, even if those ideas were false.
In Astronomy, for example, the distinction between the solar system and the universe wasn't clear up until modern times.
The ancient Greeks believed that what we called the solar system was in fact the entire universe,
and that the universe was geocentric.
Geocentric means Earth-centered, so the geocentric view holds that the Sun, the planets, and the stars, all revolve around the earth, which is stationary.
Of course, we now know that the planets including the Earth revolve around the Sun,
and that the solar system is only a tiny part of the universe.
So, why did the ancient Greeks believe that the Earth was the center of the universe?
Well, it made sense to them.
Observations of the sky make it appear as if the Sun, the moon, and the stars all revolve around the Earth everyday, while the Earth itself stayed in one place.
And this view is also supported by their philosophical and religious beliefs about the origin and structure of the universe.
It was presented in the works of well-known Greek philosophers as early as the fourth century B.C.E., and the geocentric theory continue to prevail in Western thought for almost 2,000 years, until the 17th century.
Now what's the especially interesting is that when astronomical observations were made that seemed to be inconsistent with the geocentric view, the ancient Greeks did not really consider alternative theories.
It was so intuitive, so sensible that the Earth was the center of the universe that astronomers found ways to explain those seemingly inconsistent phenomena within the geocentric view.
For example, Greek astronomers made excellent very accurate observations of the movements of the planets,
but the observations revealed a bit of a problem.
The geocentric theory said, that the planets would move around the Earth in one direction.
However, astronomers noticed that at times several planets seem to stop moving in one direction and start moving backward in their orbits around the Earth,
and they came up with a theory that these planets themselves moved in smaller circles called epicycles as they travelled around the Earth.
Here's a picture of what they imagined.
You see how this epicycle theory could account for the seemingly backward motion of the planet.
Of course, today we know that this appearance of backward motion is caused by the fact that Earth, as well as other planets, all move in their own orbits around the Sun, and the relative movements of the planets with respect to each other can get quite complex.
However, there were a few astronomers in Greece and other places who didn't agree with the geocentric view, for example, a Greek astronomer, who lived in the third century B.C.E.
He proposed the theory that our planetary system might be heliocentric, his name was Aristarchus.
Heliocentric means Sun-centered that the Earth revolves around the Sun.
Aristarchus recognized from his calculations that the Sun was much larger than the Earth and other planets.
It was probably this discovery that led him to conclude that the universe is heliocentric.
I mean, isn't it more sensible to think that a smaller heavenly body would orbit a larger one, rather than the opposite?
However, his proposition was rejected largely based on other scientific beliefs held at the time, which all made sense in a way even if they were incorrect.
Let me mention two objections Greeks made to Aristarchus's theory.
First, they believe that everything that moves creates its own wind so to speak everyone has this experience when you are running, right?
So, they thought that if the Earth itself was moving, there would have to be a constant wind blowing, sweeping them off their feet, and of course, there wasn't.
And second, the idea of an Earth that moved didn't fit in with the ancient Greeks' understanding of gravity.
They thought that the gravity was basically a natural tendency of all things to move towards the center of the universe,
which was the Earth, or the center of the Earth,
so that explains why apples and other falling objects were falling straight down.
If the Sun was at the center of the universe, things would fall toward the Sun and away from the Earth, which of course they didn't.
So these were some of the reasons they rejected the heliocentric theory. "
L21L2
"Listen to part of a lecture in a Computer Science class. The professor is discussing software engineering.We've been talking about the software development cycle, and today I'd like to move on to the next stage of that cycle - testing, and why finding bugs during testing is actually a great thing.
Eh... eh... the quality of the software product often relies heavily on how well it's been tested. Liz?
Um... just a quick thing. Bugs is the word for problems in the program code, correct?
Yeah, in code or in a computer itself.
There is a bit of a story behind that term.
Um... back in the 1940s, when the computer industry was just starting, a group of computer scientists was working late one night, and there was a problem in one of the computers' circuits.
When they examined it, they found a five-centimeter long moth caught in there.
Once they debugged the computer, it worked just fine.
And ever since then, all kinds of computer problems have been known as bugs.
Anyway, you want to find bugs while the software is still in the development and testing phases.
Finding them when the software product has already been put on the market can be quite embarrassing.
Generally speaking, every software development project has a group of testers and a group of developers. Jack?
And they are different people?
They are generally completely different groups of people.
My personal opinion is that they have to be different groups of people because developers often have a bias towards their own work, and it blinds them to certain problems that might be obvious to somebody else.
So it is always good to have a different set of eyes go in there and make sure that everything is tested properly.
Ok, now, here's the key.
Developers and testers have different mentalities.
The mentality of the software developer is constructive, creative.
They are spending long hours working together to create and build something new.
A software tester, on the other hand, their entire goal is to look at this product and find problems with it, to improve it.
Now, this difference between the testers and the developers can lead to an environment where there is a bit of friction.
And that friction sometimes makes it difficult for the two teams to work together.
There were two projects that I worked on a couple of years ago.
One, which I'll call Project Split, where, the testing and development teams did not work well together.
And the other, I'll call Project Unity, during which both teams worked very well together.
Now, during Project Split, we had defect meetings where the developers and the testers met together, eh... eh... to discuss various problems and how they should be fixed.
And you could sense the conflict just by walking into the room.
Literally, the testers and the developers sat on opposite sides of the table.
Um... and... and the developers were very defensive about the feedback.
Well, if bugs are being pointed out they wouldn't be too happy since it's their work.
Exactly. Now, because the two teams weren't working well together, the fixes were coming very very slowly.
And you know, a lot of times when you fix bugs you introduce new bugs, or you discover bugs at other areas that only come to light because something has been changed, so fixing all those new additional bugs was also being delayed.
Um... the test process went on much longer than expected and we ended up having to put the product on the market with known bugs in it, which was obviously not ideal.
Ok, and what about Project Unity? How was it different?
Um... this was different because the two teams worked closely together during the defect meetings, instead of putting up walls.
Um... we didn't even talk about, you know, who should fix this, who is at fault.
We all acknowledged what needed to be fixed.
So if we had ten bugs, we said, ""Hey, you know what? Let's do this one first because this would expose another whole bunch of defects that we haven't even seen yet.""
So we were being proactive and effective.
And because we were so much more effective with our time, we were actually able to do more than just fix the bugs, we even put in some improvements that we hadn't planned. "
L21C2
"Listen to a conversation between a student and her public relations professor.Hi, professor Gordin, I really learned a lot from your lecture, the one about analyzing all those different segments of the population.
Oh, the official term is audience, right?
I never imagine that one company could have over thirty audiences to communicate with.
Yeah, a lot of students are taken aback by this, and some public relations consultants don't figure it out until they've worked in the field a while.
Everyone thinks, public relations, eh, PR is easy, but there's a lot to it.
You really got to know what you are doing.
Absolutely. So, Stacy, your email implied that you needed my advice about graduate school?
No, since my undergraduate degree will be in public relations, I've already decided to get a master's degree in marketing.
Sorry, I wasn't clear.
My issue is, I have got two require courses and two electives.
I am trying to figure out which elective course is to take.
My advisor suggested economics and accounting, but I am not really sure.
About?
Well, I endured accounting and economics in high school and barely stayed awake, they were so ...
Ok, Ok. I hear you.
Eh... you say you wanted a master's in marketing, you have got one more semester till graduation.
Have you taken any marketing courses yet?
No, I figured I've got the marketing basis already since I have taken every PR in communication courses offered here.
Well, there's some overlap between PR and marketing, but there are important differences too.
Marketing focuses on selling your product or service, eh, you know, attracting customers through advertising, and also building relationships with customers.
That's what a marketing department does.
PR is all about, it involves relationships too, that's why I am saying the two fields overlap.
But in PR, you are developing relationships with a wider range of audiences.
Right. Like employees, suppliers, the media.
I do understand this in theory, but aren't you still selling your product, just in a different way?
Not necessarily. Ok, do you remember that PR strategy I alluded to the other day?
The one our university uses, a strategy that doesn't overlap with its marketing strategy?
You mean how the university invites local residents to attend certain lectures and classes for free?
Yeah, this cultivates a sense of good will and helps the university avoid becoming isolated from the larger community.
Bringing neighbours into our classrooms is good PR, but it is not marketing since our neighbours aren't our customers, for the most part.
That's why I want to focus on marketing in graduate school.
Wouldn't having expertise in PR and marketing give me more career options?
Yeah, but you'll also want to enjoy your work.
So for your electives, why don't you take advertising principles and intro the marketing, which I teach.
This way, you'll find out if marketing is something you really want to pursue.
Graduate School tuition is expensive, and these courses will give you a good overview of the field before committing yourself.
I wish my advisor had suggested those courses.
Well, I am someone who has worked in both marketing and PR, so I can offer a different perspective than someone who only teaches. "
L21L3
"Listen to part of a lecture in a biology class.Probably back in some previous biology course you learned that snakes evolved from lizards, and that the first snakes weren't venomous and then along came more advanced snakes, the venomous snakes.
Ok, venomous snakes are the ones that create poisonous substances or venom, like the snakes of the viper family or cobras, then there is non-venomous snakes like constrictors and pythons.
Another family of snakes, the colubrids, don't really fit neatly into either category though.
Colubrids, and you probably learned this too, although they are often classified as venomous snakes, they are actually generally non-venomous.
They are classified as venomous snakes because they resemble them, their advanced features more than the other non-venomous snakes.
Now, what if I told you that there is a good chance that most everything I just said is wrong?
Well, everything except the part about snakes evolving from lizards.
See, the basic theory about snake evolution has been challenged by a recent study that revealed a whole new understanding of evolutionary relationship for reptiles, you know, which reptiles descended from which ancestors.
The researchers study the proteins in the venom genes of various species of colubrids.
Emm... snake venom is a mixture of proteins, some toxic, poisonous, and some not.
By analyzing the DNA, the genetic material of the proteins, the researchers could focus on the toxic genes and use them to trace the evolution of snake venom, and from this, the evolution of snakes.
Traditionally, to understand evolutionary relationships, we looked at various easily observed physical characteristics of animals, their skeleton, the size of their brain, and... and then classify them based on similarities and differences.
The problem with this method is that characteristics that appear similar may actually have developed in quite different ways.
For example, some venoms are chemical-based, and others are bacteria-based, so they clearly had to have developed along different routes and may not be as closely related as we thought.
Now, and not everyone will agree about this.
The classification based on DNA seems to be much more reliable.
Ok, back to the research.
The researchers found that venom evolved before snakes even existed, about a hundred million years before.
Now, a couple of venomous lizards were included in this study.
And the researchers found some of the same DNA in their venom as in the snakes' venom.
This suggested that the common ancestor of all snakes was actually a venomous lizard, which means that actually, according to this research, anyway, in terms of the snakes' ancestry, there is no such thing as a non-venomous snake, not even colubrids.
What separates colubrids from other snakes we have been classifying is venomous, is not the lack of venom, but the lack of an effective way to deliver the venom into its prey.
In most venomous snakes, like vipers and cobras, the venom is used to catch and immobilize the prey; but in colubrids, venom drips onto the prey only after the prey is in the snake's mouth.
So for colubrids, the venom must serve some other purpose, maybe linked to digesting prey.
As the different families of venomous snakes evolved, the teeth moved forward, becoming larger, and the venom became stronger, so the evolution of the obvious venomous snakes, like cobras and vipers, is about the evolution of an efficient delivery system, not so much the evolution of the venom itself.
So, if there are no truly non-venomous snakes, were the so-called non-venomous snakes, like constrictors and pythons, were they venomous at some point in their evolution?
Well, that's not clear at this point.
Constrictors have evolved to kill their prey by crushing, but perhaps they once were venomous, and then at some point their venom-producing apparatus wasn't needed anymore, so it gradually disappeared.
There's one species of snake, the brown tree snake, that uses both constriction and venom, depending on its prey.
So, well, it is possible.
So, we have these new concepts of snakes' evolution and a new DNA database, all these information on the genetic makeup of snake venom.
And what we have learned from this has led researchers to believe that venom proteins may have some exciting applications in the field of medical research.
You see, venom alters biological functions in the same way certain drugs do, and the big benefit of drugs made from snakes venom would be that they target only certain cells, so maybe that'll create fewer side effects.
Now, it sounds far-fetched, venom is the basis for human drugs.
So far, only one protein has been targeted for study as a potential drug, but who knows, maybe someday. "
L21L4
"Listen to part of a lecture in an Art History class.All right, so today we are moving on to Alice Neel, N-E-E-L.
Um... Alice Neel painted portraits, she was born in Pennsylvania, and she lived from 1900 to 1984.
And I guess you might say, she experienced difficulties as an artist.
She was in her 70s, before she had her first major solo exhibition.
Um, and this is due at least in part to eh... or... because of photography.
After photography became regarded as an art form, portrait painting became less prestigious, less respected as an art form.
And, well, art photography kind of took its place, so you can imagine that a portrait artist, would have had a hard time finding acceptance.
Eh, but the real reason I want to look at Neel, is that I really find her style... eh, she had interesting ways of portraying people.
She combined some elements of realism.
What's realism, Alison?
It's like painting something exactly how it is, so an artist would try to make it as accurate, um... and objective as possible.
Painting stuff just how it appears on the surface.
Ok, good.
So Neel combined realism with, actually, with expressionism.
And that is? We, we just covered this.
Um... It's into emotion, like artists are trying to, well, express themselves through the painting, right?
Yep. The artist is depicting subjective emotions, showing the inner reality as interpreted by the artist rather than the outward form.
So the image itself might be distorted or exaggerated in some way.
The expression overrides objective representation.
Ok, so, Alice Neel combined these two styles... Yes?
Em... How is that even possible?
How can you portray something exactly as it is and at the same time distort it with emotions?
I don't get it.
All right, good question.
It is actually a good lead-in to some of the techniques that Neel used, that she employed to bridge that contradiction.
In a minute, I'll show you some of her portraits, and I'll want you to notice a few things about them.
First, Neel's use of bold color.
All right? You'll see she uses color to convey emotion and feeling, like the subjects' clothing for instance, it appears brighter than it really is.
And the subjects, the people being portrayed, Neel paid special attention to faces.
The way she paints the eyes and how the faces are portrayed, these are quite realistic, like the realists' work.
But another thing Neel did was use elongated, sort of stretchy figures.
But didn't a lot of expressionist painters do that?
So really you're saying that Neel's techniques were similar to what other artists were doing.
What was it that she did, that was like all her own?
Ok, well, I think it has to do partly with the way she combined these techniques.
So, for example, those realistic faces and eyes, but bright, distorted figures.
It is a mix.
You'll see that her portraits do reflect reality, the people that were actually sitting there.
Realism was important in the sense that she wanted to show people as they really were, much like a photographer would.
But Neel wasn't satisfied with photo-like realism, she went beyond that.
And this is where expressionism comes in.
She believed in capturing the whole person, not just what was on the surface, that's where the expressionists' distortion is important, in an attempt to reveal the subjects' character or personality.
But Neel's paintings are distinctive for her time in part because they are portraits.
Remember I said that photography and art photography had largely taken the place of portraiture, to the extent that some critics had declared the genre of portraiture to be dead.
But Neel felt that painting should reflect reality, a real realist's stance you could say.
And to her, individuals, people best reflect the reality of their time, of the age that they lived in, so she painted portraits.
And if you look at her work, we are talking in the vicinity of three thousand paintings.
If your looked at them, it is like this gallery of the whole century, an enormous range of subjects: families, women, children, artists, people in poverty - these paintings really span class, age and gender.
It is like she transformed the genre, it is not just formal depictions of presidents and ancestors any more.
But keep in mind that she was doing this when abstract art dominated the art scene.
Representations of people weren't fashionable in the art world.
And it wasn't until fairly late in the century that critics recognized the power of what she did. "
L22C1
"Listen to a conversation between a student and a faculty advisor for the university newspaper.Hi, I am sorry to bother you, but...
Yes?
This is about the newspaper.
Oh, Ok. Well. I am only the advisor; the newspaper office is off campus on Pine Street.
Eh... what was it? Did you want to work for the paper? We are always looking for writers.
Well, my problem was with the writing actually, with an article that was published in yesterday's newspaper.
Oh? Which one?
The one about the student government and its president Sally Smith.
Is this something to do with what the editor wrote about the statue?
Eh, the statue at the main entrance of the university?
Well, that's part of it.
But you know, the editor used the situation to say some really unfair things, about the student government, and the president Sally Smith in particular.
I think the paper should publish a retraction, or the very least an apology to Sally.
Ok. Um... if I remember correctly, what you are referring to wasn't a news story, but an editorial, right?
Eh, it was on the opinion page, it was signed by one of the editors, and was clearly labeled as commentary.
Well, yes. But the thing about the statue, Sally made this simple comment that was in really bad condition and should be replaced.
And, well, the tone in the editorial was demeaning.
It accused her of not respecting the past and it had some personal stuff that seemed unnecessary.
Wait a minute. Remind me.
Well, you know, it implied that Sally doesn't know much about the university's history and it called her a big city politician because she's from Boston.
It's just mean-spirited, isn't it?
Haven't you heard the saying ""all publicity is good publicity""?
Well...
I'd say the article is bringing attention to the student government organization, which is pretty invisible.
Eh, you rarely hear about what the student government is doing.
But this article...
And the piece, well, yeah, it had a bit of an exaggerated tone.
It was satirical, or at least it was meant to be.
It wasn't only poking fun at Sally, but the whole idea that our school is sort of rural, and you know, not cosmopolitan.
Well, none of us thought it was very funny.
Well, sometimes it's best just to roll with it.
It is just a cliché; everybody knows it is not true.
But I thought we could expect better than that here.
Well, I am certainly in favor of getting a variety of viewpoints.
So why don't you go talk to the editor, Jennifer Hamilton, and tell her you want equal time?
You or Sally could write a response.
Really? She would let us do that?
Didn't she write it?
I'll let Jennifer know you are coming, she feels the same way I do. She is journalism major.
She would be happy to publish another point of view. "
L22L1
"Listen to part of lecture in an anthropology class.One of the big questions when we look at prehistory is: Why did early states form?
Well, to begin we'd better define exactly what we mean when we talk about states.
The human groups that are the smallest and have the least social and political complexity, we call bands.
The groups that are the largest and most socially and politically complex, we call states.
So, the level of complexity here refers to the organization of people into large, diverse groups, and densely populated communities.
And there are four levels in total: bands, tribes, chiefdoms and states.
But, but back to my original question.
Why did early states form?
Why not just continue to live in small groups?
Why become more complex?
One theory called the environmental approach hypothesizes that the main force behind state formation was population growth.
It assumes that centralized management was critical to dealing with issues caused by sudden population surges, like a strain on limited food supplies.
At the least complex end of the spectrum, the few families living in bands are able to meet their own basic needs.
They usually hunt together and forage whatever foods are available to them, instead of domesticating animals and planting crops.
In order to efficiently take advantage of the wild foods available, bands are often nomadic and move around following herds of animals.
This strategy is feasible when you have a small population.
But when you have a large population, well, the whole population can't just get up and move to follow a wild herd of animals.
So you need sophisticated technologies to produce enough food for everyone.
And there is an increased need to resolve social problems that arise as people begin to compete for resources.
To manage intensified food production, to collect, store and distribute food, you need centralized decision-making, centralized decision-makers.
It's the same thing when it comes to maintaining social order.
You need to create and efficiently enforce a formal legal code.
It makes sense to have a centralized authority in charge of that, right?
So a hierarchy forms.
By definition, states had at least three social levels.
Usually, an upper class of rulers, a middle class comprised of managers and merchants, and a lower class of crafts producers and agricultural laborers.
The environmental approach hypothesizes that states appear in certain environmental settings, settings which have a severe population problem or a shortage of agricultural land.
But not everyone agrees with the theory.
It definitely has some weaknesses.
For example. states have developed in places like the mild lowlands of Mesoamerica and in Egypt's Nile River Valley.
Both places had vast areas of fertile farmland, no shortage of agricultural land.
And what about population increase?
Well, there were some early states that formed where there wasn't any sudden population increase.
So it seems that these are valid criticisms of the environmental approach. "
L22L2
"Listen to part of the lecture in an Astronomy Class.Today, I want to talk about a paradox that ties in with the topic we discussed last time.
We were discussing the geological evidence of water, liquid water on Earth and Mars three to four billion years ago.
So what evidence of a liquid water environment did we find in rock samples taken from the oldest rocks on Earth?
Um, like pebbles, fossilized algae?
Right. And on Mars?
Dry channels?
Good.
All evidence of water in liquid form, have large quantities of it.
Now remember when we talked about star formation, we said that as the star ages, it becomes brighter, right?
Hydrogen turns into Helium, which releases energy.
So our standard model of star formation suggests that the Sun wasn't nearly as bright three to four billion years ago as it is today, which means the temperatures on Earth and Mars would have been lower, which in turn suggests?
There would have been ice on Earth or Mars?
Correct.
If the young Sun was much fainter and cooler than the Sun today, liquid water couldn't have existed on either planet.
Now this apparent contradiction between geologic evidence and the stellar evolution model became known as the faint young Sun paradox.
Now there have been several attempts to solve this paradox.
First, there was the greenhouse-gas solution.
Well, you are probably familiar with the greenhouse gas effect.
So I won't go into details now.
The idea was that trapped greenhouse gases in the atmosphere of Earth and Mars might have caused temperatures to rise enough to compensate for the low heat the young Sun provided.
And so it would have been warm enough on these planets for the liquid water to exist.
So what gas do you think was the first suspect in causing the greenhouse effect?
Um, carbon dioxide i guess, like today?
In fact, studies indicate that four billion years ago, carbon dioxide levels in the atmosphere were much higher than today's levels.
But the studies also indicate that they weren't high enough to do the job - make up for a faint Sun.
Then some astronomers came up with the idea that atmospheric ammonia may have acted as a greenhouse gas.
But ammonia would have been destroyed by the ultra-violet light coming from the Sun and it had to be ruled out too.
Another solution, which is proposed much later, was that perhaps the young Sun wasn't faint at all, perhaps it was bright.
So it's called the bright-young-Sun solution, according to which the Sun would have provided enough heat for the water on Earth and Mars to be liquid.
But how could the early Sun be brighter and hotter than predicted by the standard model?
Well, the answer is mass.
You mean the Sun had more mass when it was young?
Well, if the young Sun was more massive than today's, it would have been hotter and brighter than the model predicts.
But this would mean that it had lost mass over the course of four billion years.
Is that possible?
Actually, the Sun is constantly losing mass through the solar wind, a stream of the charged particles constantly blowing off the Sun.
We know the Sun's current rate of mass loss.
But if we assume that this rate has been steady over the last four billion years, the young Sun wouldn't have been massive enough to have warmed Earth, let alone the Mars, not enough to have caused liquid water.
Maybe the solar wind was stronger then?
There is evidence that the solar wind was more intense in the past.
But we don't know for sure how much mass our Sun's lost over the last four billion years.
Astronomers tried to estimate what solar mass could produce the required luminosity to explain liquid water on these planets.
They also took into account that with a more massive young Sun, the planets would be closer to the Sun than they are today.
And they found that about 7% more mass would be required.
So the young Sun has 7% more mass than our Sun?
Well, we don't know.
According to observations of young Sun like stars, our Sun may have lost as much as 6% of its initial mass, which doesn't quite make it.
On the other hand, this estimate is based on a small sample, and the bright-young-Sun solution is appealing.
We simply need more data to determine the mass loss rate of stars.
So there's reason to believe that we will get an answer to that piece of the puzzle one day. "
L22C2
"Listen to part of a conversation between a student and his music history professor.So, I was wondering what I could do to improve my paper before the final draft is due.
Well, Michael, I have no problem with your writing style. It's graceful and clear.
Eh, and it's interesting that you are writing about your grandmother's piano concert.
Yeah, when you said we had to attend a concert and write about it, I immediately thought of her.
I have been to lots of her concerts. So I am really familiar with her music.
That's not necessarily an advantage.
Familiarity sometimes makes it hard to see things objectively.
So I shouldn't write about my grandmother?
No, no, no. I am just talking in general.
But as I mentioned in my comments, I'd like you to place your grandmother's concert in... in a broader context.
Yeah, I saw that, but I wasn't sure what you meant.
I mean, I mentioned my grandmother's childhood, how much her parents love music, how she played the piano at all our family gatherings.
Ok. I see what happened now.
By broader context, I mean how the concert relates to some period in music history.
I see. Ok. Um... I have an idea.
Ok.
Well, as you read in my paper, my grandmother performs classical music.
Yes.
That's her true love. But for most of her career, she performed jazz.
She originally studied to be a classical pianist.
But jazz was in its heyday back then, and when she got out of the conservatory, she was invited to join a jazz orchestra.
And the opportunity was just too good to turn down.
Really. Well, that's fascinating, because she probably had to reinvent her whole musical style.
She did. But jazz was where the money was at that time, at least for her.
But she eventually went back to classical?
Right. But only recently.
Ok.
So if I can show how her choices relate to what was happening in the world of music at the time?
I think that might work very nicely.
And if I do that, I guess I'll have to like, interview her.
Right.
And I guess that would mean...
You'll have to rewrite most of your paper.
Ouch!
Yeah. Would an extra week ease the pain?
Definitely.
Ok. So are there other musicians in your family?
Yeah. My mother plays piano, too. Not as well as my grandmother, but...
And you?
I don't play any instruments, but I sing in the university choir.
In fact, we are performing next week, and I have a solo.
That's great! Could I tell the class about your concert?
Um.... sure. But about my paper, what question should I be asking my grandmother?
You know what, I have a meeting now.
Why don't you come to class a few minutes early tomorrow?
Will do. "
L22L3
"Listen to part of a lecture in a zoology class.A mass extinction is when numerous species become extinct over a very short time period, short, geologically speaking, that is, like when the dinosaurs died out 65 million years ago.
And the fossil record, it indicates that in all the time that animals have inhabited Earth, there have been five great mass extinctions, dinosaurs being the most recent.
In each of the others up to half of all land animals and up to 95% of marine species disappeared.
Well, Today we are witnessing a sixth mass extinction, but unlike the others, the current loss of biodiversity can be traced to human activity.
Since the Stone Age, humans have been eliminating species and altering ecosystems with astounding speed.
Countless species have disappeared due to over-hunting, habitat destruction and habitat fragmentation, pollution and other unnatural human causes.
So, as a way of repairing some of that damage, a group of conservation biologists has proposed an ambitious, or, some might say, a radical plan, involving large vertebrates, or, megafauna.
Megafauna include elephants, wild horses, big cats, camels, large animals.
Eh, actually, the proposal focuses on a particular subset of megafauna, the kind that lived during the Pleistocene epoch.
OK.
The Pleistocene epoch, most commonly known as the Ice Age, stretched from 1.8 million to 11,500 years ago.
In the Americas, most megafauna began disappearing by the end of the pleistocene.
So here is a biologist's idea.
Take a select group of animals, Megafauna from places like Africa and Asia, and introduce them into other ecosystems similar to their current homes, beginning in the Western Unite States.
They call their plan Pleistocene rewilding.
Now the advocates of Pleistocene rewilding cite two main goals.
One is to help prevent the extinction of some endangered megafauna by providing new refuges, new habitats for them.
The other is to restore some of the evolutionary and ecological potential that has been lost in North America.
What do I mean by restore evolutionary potential?
Well, as you know, the evolution of any species is largely influenced by its interaction with other species.
So during the Pleistocene epoch... let's take the now extinct American ""Cheetah"" for instance.
We believe it played a pivotal role in the evolution of the pronghorn antelope, the antelope's amazing speed, to be exact, because natural selection would favor those antelope that could outrun a cheetah.
When the America cheetahs disappeared, their influence on the evolution of pronghorn and presumably on other prey animals stopped.
So it is conceivable that the pronghorn antelope would have continued to evolve, get faster maybe, if the cheetah was still around.
That's what means by evolutionary potential.
Importing African Cheetahs to the western Unite State could, in theory, put the pronghorn back onto its... natural evolutionary trajectory according to these biologists.
Another example is interaction of megafauna with local flora, in particular, plants that rely on animals to disperse their seeds.
Like pleistocene rewilding could spark the re-emergence of large seeded the American plants, such as the maclura tree.
Many types of maclura used to grown in North America, but today, just one variety remains and it is found in only two states.
In the distant past, large herbivores like mastodons dispersed maclura seeds, each the sizes of an orange in the droppings.
Well, there aren't any mastodons left, but there are elephants, which descended from mastodons.
Introduce elephants into that ecosystem and they might disperse those large maclura seeds, like their ancestor did.
Get the idea?
Restoring some of the former balance to the eco-system?
But as I alluded to earlier, Pleistocene rewilding is extremely controversial.
A big worry is that these transplanted megafauna might devastate plants and animals that are native to the western United States.
In the year since the Pleistocene epoch, native species have adapted to the changing environment there.
Plants, smaller animals, they have been evolving without megafauna for millennia.
Also animal species that went extinct 11000 years ago, uh, some are quite differently genetically from their modern-day counterparts, like elephants do not have thick coats like their mastodon ancestors do when they graze in the prairie of the America West during the Ice Age.
Granted, the climate today is not as cold as it was in Pleistocene.
But winters on the prairie can still get pretty harsh today.
And there are many more considerations.
Well, you see how complex this is.
If you think about it though, the core problem with this sixth mass extinction is human interference.
Pleistocene rewilding is based on good intentions, but you know, it probably would just be more of the same thing. "
L22L4
"Listen to part of a lecture in the music history class.So, uh, if you were a musician in the United States in the early 20th century, where could you work?
Same as now, I suppose. In an orchestra, mainly.
Ok. And where would the orchestra be playing?
Um, in a concert hall or a dancer hall?
That's right.
And a smaller groups of musicians were needed in theaters as accompaniment to visual entertainment, like cabarets and variety shows.
But the largest employer for musicians back then was the film industry, especially during the silent-film era.
Really?
You mean being a piano player or something?
I thought movie theaters would have used recorded music.
Well, no.
Not during the silent-film era.
We are talking a period of maybe thirty years where working in movie theaters was the best jobs for musicians.
It was very well-paid.
The rapid growth of the film industry meant movie theaters were popping up everywhere.
So suddenly there was this huge demand for musicians.
In fact, over 20000 jobs for musicians were gone, disappeared, at the end of the silent-film era, 20000.
OK.
So, from the beginning, music was a big part of film, even at the first..
Excuse me, professor, I think I read somewhere that they used music to drown out the sound of the film projectors?
Yeah, that's good story, isn't it?
Too bad, it keeps getting printed as if it were the only reason music was used.
Well, think about it.
Even if that were the case, noisy projectors were separated from the main house pretty quickly, yet music continued to accompany film.
So, as I was saying, even the very first public projection of a movie had piano accompaniment.
So music was pretty much always there.
What's strange to me though, is that at first film music didn't necessarily correspond to what was on the screen.
You know, eh, a fast number for a chase, deep bass notes for danger, something light and humorous for comedy.
And that's instantly recognizable now, even expected.
But in the very early days of the film, any music was played.
A theater owner would just buy a pile of sheet music and musicians will play it, no matter what it was.
Pretty quickly though, thankfully, everybody realized the music should suit the film.
So eventually, film makers tried to get more control over the musical accompaniment of their films, and specify what type of music to use and how fast or slow to play it.
Are you saying there was no music written specifically for a particular movie?
Yeah. Original scores weren't common then.
Rarely a filmmaker might send along an original score composed especially for a film, but usually a compilation of a music that already existed would be used.
Yeah, that was a good time for a lot of musicians.
But that all changed with the introduction of sound on film technology.
Actually, even before that,organs could mimic a number of instruments, and also do some sound effects.
So they were starting to replace live orchestras in some movie theaters, and it only takes one person to play an organ.
OK, but even after that, some one still had to play the music for the sound recordings, the soundtracks.
Yeah, but think of all the movie theaters there were, most employing about six to eight musicians, some even had full orchestras.
But in early 1930s, most theater owners installed new sound systems.
So suddenly, a lot of musicians were looking for work.
Once recording technology took off, studio jobs working exclusively for one film company, eh, studio jobs did become available.
But the thing is each major movie company pretty much had only one orchestras for all their productions, a set number of regular musicians.
So if you could get it, studio musician was a good job.
If you were cut out for, musicians had to be able to read music very well, since the producers were very conscious of how much money they were spending.
They didn't want to waste any time.
So a musician was expected to play complicated pieces of music pretty much without any preparation.
If one couldn't do it, there were plenty of others waiting to try.
So there was a lot of pressure to do well. "
L23C1
"Listen to a conversation between a student and the director of campus activities.I'm here 'cause... well, there's something I don't understand.
I set an announcement for an event.
And this morning I checked the events section of the university's website.
And nothing, there is no mention of it.
And when did you submit this request?
Last Wednesday. I followed the instructions very carefully.
I am sure it was Wednesday, because I know announcements have to be submitted three business days ahead of the posting day.
And what's it for?
A reading.
A reading?
Yes. A poetry reading.
Oh, oK. And when is it?
In three days. It is an author from France we have been trying to get for a while.
And now that he has finally agreed to come, no one will be there.
Wow. This person is really coming all the way from France?
Oh, no. He is teaching in New York City this year.
We were able to sell him on the idea by promising there will be a nice size crowd.
I felt confident about that. Because I know how enthusiastic our group is.
And your group... do you have a name?
Um... it is kind of a loose group, you know, just a bunch of students in the French department who are interested in French literature.
There's no formal structure or anything.
I guess you could call us the French Literature Reading Group.
OK. And it is a recognized group? By the university, I mean.
No.
OK.
But the French Department is funding this, on the condition that we do all the legwork.
All right. Hold on a second while I check.
Well, it looks like we did receive your announcement last Wednesday.
Uh, looks like the editors must have decided not to include your event in this week's listings.
Not included? Why?
Well, we don't post things automatically.
We get so many requests that we couldn't possibly post them all.
So events that are thought to be too specialized, without the potential for really wide appeal...
Wow, I got to say that does surprise me.
What am I going to do now? I mean, he really is quite famous.
I really do think there would be a genuine interest beyond my group.
It would be a shame if no one shows up because there isn't enough publicity.
Is there anyone else I can talk to?
I don't think that would do you much good since we are already working on next week's schedule.
But maybe you could ask the French department to post the announcement on its website.
And maybe you could approach some other departments as well, you know, relevant ones.
I knew we should have done a poster, but everybody was like, oh, you can just post it online.
In any event, thanks for your help. It's something to consider. "
L23L1
"Listen to part of a lecture in an archaeology class.I was talking to one of my colleagues in the physics department the other day, and we ended up discussing how one discovery can change everything.
My colleague mentioned how the theory of relativity completely changed the field of physics.
and anyway, that conversation got me thinking about archaeological finds that really changed our understanding of ancient civilizations.
So I want to talk about the discovery of the Antikythera Mechanism.
The Antikythera Mechanism was found a hundred years ago, under water in an ancient Greek shipwreck in the Mediterranean Sea.
It was in extremely poor condition and in many corroded pieces.
But once we figured it out what it was and reconstructed it,well, I simply don't have the words to convey how extraordinary this find was.
The Antikythera Mechanism is a relatively small device, roughly the size of a shoebox, made of gears fitted inside a wooden case.
In its original state, there were rotating dials and other indicators on the top, with letters and drawings showing the Sun, the phases of the moon and different constellations.
Inside the box, bronze gears would have rotated the displays.
The displays, uh, the indicators of the Antikythera Mechanism, would then moved to show the motion of the Sun and moon relative to the planets and stars.
The device could be used to tell the different phases of the moon and much more.
Well, scientists have recently analyzed the inscriptions on the mechanism and re-examine the other cargo in the ship wreck, and the evidence makes an absolute case that this device dates back to ancient Greece somewhere between 150 and 100 B.C.E.
What makes that so fascinating is that before we found the Antikythera Mechanism, the earliest device we had that could track the Sun and moon like this was invented over 1,000 years later.
So when this was first found, people literally would not believe it.
Some of my colleagues insisted it had to have been made well after 100 B.C.E.
But this physical evidence was conclusive. It was that old.
Of course part of what made this find so unusual is that the Antikythera Mechanism is constructed of bronze.
Now, it is not that bronze was all that rare in Greece then, it is just that bronze was valuable and could easily be recycled.
It would have been relatively easy for a person with knowledge of metals to melt down bronze objects and forge them into,oh, say, coins.
Bronze was used to made money back then.
Or mold the bronze into anything else of value for that matter.
We are very fortunate that the device ended up under water, because otherwise it probably would have ended up recycled into who knows what.
Now, it was a challenge to figure out the Antikythera Mechanism.
It spent over 2,000 years at the bottom of the sea before it was discovered.
And even after it was discovered, it was still a number of years before we really understood what it was.
You see, the mechanism had corroded underwater, and many of the gears were stuck together in a mess.
Cleaning it was only partly successful.
We could only get a good look at the structure of the gears after gamma-rays were used to see inside, very similar to the way X-rays are used to see your bones.
Now, once we got a good look inside, we saw a really complex device.
The many gears not only moved in a way that could indicate the phases of the moon.
The Antikythera Mechanism also tracked both the lunar year and the solar year.
Additionally, the gears also moved to match the motions of the planet and predicted eclipses.
But one thing that is particularly notable is that the mechanism was so precise that it even took into account a particular irregularity in the moon's orbit, which requires some very complex math to replicate in mechanical device.
You could say that the Antikythera Mechanism was a very precise calendar, which stands to reason-calendars were very important to ancient peoples.
Religious festivals had to be held at the right time of year, crops needed to be planted at the right time as well.
And let's not forget that eclipses in planetary motions had important symbolic meanings. "
L23L2
"Listen to part of a lecture in an environmental science class.Basically, a cloud either contributes to the cooling of Earth's surface or to its heating.
Earth climate system is constantly trying to strike a balance between the cooling and warming effects of clouds.
It's very close, but overall the cumulative effects of cloud is to cool Earth rather than heat it.
And this balance between the amount of solar radiation, energy from the Sun, that's absorbed by Earth, and the amount that's reflected back into space, we call this ""Earth's radiation budget"".
And one way we keep track of the ""radiation budget"" is by looking at the ""albedo"" of the different surfaces on the planets.
A surface's ""albedo"" is the percentage of incoming solar energy, sunlight, that's reflected off the surface back into space.
Oceans have a low albedo, because they reflect very little energy.
Most of the solar energy that reaches the ocean gets absorbed and heats the water.
Um, rain forests also have low albedo.
Well, by contrast, deserts and areas covered by ice and snow, these places have high albedos.
And clouds, in general, clouds also have high albedos.
That means that a large percentage of the solar energy clouds recieve is reflected back into space.
OK, now when we say that clouds have a high albedo, we are talking about the effect of all the clouds on Earth averaged together.
But different types of clouds have different reflective properties, they have different albedos.
So which type of clouds cool Earth, and which type heat it?
Well, high thin clouds contribute to heating while low thick clouds cool Earth.
High thin clouds are very transparent to solar radiation.
Like clear air.
So, they mostly transmit incoming solar energy down to Earth, there is not much reflection going on at all.
At the same time, these clouds trap in some of the Earth's heat, because of trapped heat, these clouds have an overall heating effect.
Oh, OK, so since low thick clouds are not transparent the radiation...
Exactly, they block much of the solar energy, so it never reaches Earth's surface, they reflect much of it back out into space.
So that's how clouds contribute to cooling?
Yep, and as I said earlier, this cooling affect predominates.
Now what if there was a process that could control the type of clouds that form?
Are you talking about controlling the weather?
Well, I am not sure I would go that far.
But we recently noticed an increasing cloud cover over an area of the ocean waters around Antarctica.
An increased area of low thick clouds, the type that reflects a large portion of the solar energy back to space and cools the Earth.
Well, the reason for this increased cloud cover, it turns out, is the exceptionally large amount of microscopic marine plants.
Well the current hypothesis is that these microorganisms produce a chemical, dimethyl sulfide that interacts with the oxygen in the air, creating conditions that lead to the formation of the low thick clouds we observed.
Well, that's true. It could have huge implications.
So maybe we are talking about controlling the weather, perhaps if the microorganism in Antarctica really are responsible, perhaps we can accelerate the process somehow. "
L23C2
"Listen to a conversation between a student and his English professor.Hi, Bob. How is it going? Are you enjoying the Introduction to Literature class?
Yeah, it's great. Araby, that short story by James Joyce we read last week, it was awesome.
I'm glad you like it.
Most of Joyce's work is very complex. A lot of students say that he is hard to understand.
Normally, you wouldn't tackle Joyce in an Intro class, but I'd like to give my first year students a taste of his style, his psychological approach to literature, because... mainly because it influenced other writers.
I only wish we had more class time to discuss it.
Me too. So why did you pick Araby instead of some other story?
Well, um, first you should know that Araby is one of fifteen short stories by Joyce in a book called Dubliners.
Uh, all the stories are related to one another, and they are set in the same time period.
But Araby is the easiest one to follow.
Though all the stories in the collection are written in stream of consciousness, which as you know, means they are told through the narrator's thought, through an inner monologue, as opposed to dialogue or an objective description of events.
But Araby is easier because it's linear, the story unfold chronologically.
Still, I wish we could read whole novels by Joyce and discussed them in class.
That's what happens in my Master Writer Class.
Master Writer Class?
Yeah, I teach one on Joyce every spring.
It's such a privilege, spending an entire term diving into a single body of work.
And my students, they bring so much insight to the table that it's easy to forget who the professor is.
Oh, wow. That could actually solve my dilemma, uh, what I originally wanted to ask you...
Um, I am working on my schedule for next term, and I've got room for one more course, and I'd like to take more literature.
Could I take your Master Writer Class on Joyce?
I'm sorry. I should have mentioned.
Uh, Master Writer is an advanced seminar.
So students need to get a strong foundation in literary theory and criticism before I let them enroll.
But I have gotten really good grades on all my paper so far. I'm sure I can keep up.
Couldn't you make an exception?
Your grades are excellent.
But in our intro class, you are reviewing the basics, like plots, setting and character and getting your first real exposure to different literary styles.
But why do I have to study different styles to understand Joyce's novels?
There are a lot of little details involved in interpreting literature.
And like with Joyce. His novels have very unique structures.
The only way to appreciate how unique they are is by studying a variety of authors.
Oh, OK. So could you suggest a different literature class then?
Sure. There's doctor Clain's course on nineteenth-century novels.
It's more focused than the class you're in now.
But it will build on your current knowledge base and give you the background you need.
That, plus a couple more foundational classes, and you will definitely be ready for my seminar.
Sweet. Thanks. "
L23L3
"Listen to part of a lecture in a marine biology class.We have been talking about how sea animals find their way underwater, how they navigate, and this brings up an interesting puzzle, and one I'm sure you'll all enjoy.
I mean, everybody loves dolphins, right?
And dolphins, well, they actually produce two types of sounds.
Uh, one being the vocalizations you are probably all familiar with, which they emit through their blowholes.
But the one we are concerned with today is the rapid clicks that they use for echolocation, so they can sense what is around them.
These sounds, it has been found, are produced in the air-filled nasal sacs of the dolphin.
And the puzzle is how do the click sounds get transmitted into the water?
It's not as easy as it might seem.
You see, the denser the medium, the faster sound travels.
So sound travels faster through water than it does through air.
So what happens when a sound wave um... OK.
You've got a sound wave traveling merely along through one medium, when suddenly, it hits a different medium, what does gonna happen then?
Well, some of the energy is going to be reflected back, and some of it is going to be transmitted into the second medium.
And... and... and if the two media have really different densities, like air and water, then most of the energy is going to be reflected back, very little of it will keep going, uh, get transmitted into the new medium.
I mean, just think how little noise from the outside world actually reaches you when your head is underwater.
So, how did the dolphin's clicks get transmitted from its air-filled nasal sacs into the ocean water?
Because given the difference in density between the air in the nasal cavity and the seawater, we'd expect those sounds to just kind of go bouncing around inside the dolphin's head, which will do it no good at all.
If it's going to navigate , it needs those sounds to be broadcasted and bounced back from objects in its path.
Well, turns out dolphins have a structure in their foreheads, just in front of their nasal sacs, called a melon.
Now, the melon is kind of a large sac-like pouch, made up of fat tissue.
And this fat tissue has some rather fascinating acoustical properties.
Most of the fat that you find in an animal's body is used for storing energy, but this fat, which you find in dolphins, and only in the melon and around the lower jaw.
This fat is very different, very rich in oil.
And it turns out it has a very different purpose as well.
Now, one way to overcome this mismatch in the density of air and water would be... if you could, um, modify the velocity of the sound wave, make it precisely match the speed at which sound travels through water.
And that's exactly what marine biologists have discovered the melon does.
Note that the bursa, these little projections at the rear of the melon, are right up against the air-filled nasal sacs.
And these bursa, it turns out, are what's responsible for transferring sound to the melon.
The sound waves are then transmitted by the bursa through the melon, first through a low velocity core, and then through a high velocity shell, where their speed is increased before they are transmitted into the surrounding seawater.
So now the signals can be efficiently transferred into the water, with minimal reflection.
The only other place, this special fatty tissue, like that in the melon, the only other place is found in the dolphin, is in the lower jaw.
Turns out that the lower jaw, well, it is made of a specially thin bone.
And it is very sensitive to vibrations, to sound energy traveling through the seawater.
It turns out that the jaw is primarily responsible for capturing and transferring returning sound waves to the dolphin's inner ear.
So these rapid clicks that are sent out bounce off objects, maybe a group of fish swimming over here, a boat coming from over there.
The sounds bounce off them and the lower jaw captures the returning sounds, making it possible for the dolphin to sense what's in the surrounding water and decide where to swim. "
L23L4
"Listen to part of a lecture in a choreography class.Now, when you think about choreography, well, uh, for your last assignment, you choreographed the dance that was performed on stage in front of live audience.
Now, screen dance is very different.
It is a dance routine you will be choreographing specifically to be viewed on a screen, on a computer screen, a TV screen, in a movie theater, any screen.
So the question we have to ask is, what's the difference between choreography for a live performance and choreography for on-screen viewing?
OK. Think for a minute.
When you see a movie, is it just a film of people acting on a stage?
Of course not. Movies use a variety of camera angles and creative editing.
Movies can distort time, slow movement down, or speed it up, show actors fading in and out of scenes, etc.
All of these... all of these film-making techniques, things that can't be used in a live performance, are possible in a screen dance.
Now, we'll cover these concepts in greater detail later, but you should be getting the idea that I don't want you to just film dancers on stage and turn it in as your screen dance project. Uh, Yes? Debbie.
But isn't something lost here, Professor Watson?
I am a dancer, and when I perform on stage, I am so energized by the audience's reactions, the applause.
I actually, and for a lot of dancers, it... it really inspires us.
You're right. Screen dance, which is a relatively new, isn't for everyone.
Uh, some dancers may seem reluctant to participate in your project, because they do thrive on the immediacy of performing live.
If this happens, you could point out that screen dance offers other ways for dancers to connect to their audience.
For example, dancers can express themselves, even change the whole mood of the scene through a facial expression.
And you could film close-up shots of their faces.
Facial expressions aren't as important in live performances generally, because the choreographer knows that someone in the back row of a theater may not be able to see a dancer's face clearly.
But... um, I have never used a movie camera or edited film before.
How will we learn everything we need to know to... ?
Oh, don't worry. The cameras you will be using are pretty simple to operate.
And you'll get to play with the film-editing software several times before beginning your project.
You'll also have the option of working with a student in the film department, someone who's familiar with the technology.
But the choreography and the end result will be your responsibility of course.
Could you talk some more about the film-making techniques, you know, the ones that work best for screen dances?
I'll show some of my favorite screen dances next week to give you a better idea.
But, uh, OK. Here's one technique that can create the illusion of flow in a screen dance.
You film the same dancer, entering and exiting the frame several times.
Moving slowly at first, then faster and faster.
Then in the editing room, you can digitally manipulate these images, like you might put five or ten or twenty copies of that same dancer meeting himself in the middle of the screen, to make it look like he is dancing with himself.
Obviously, this can't be done in a live performance.
Another example, in one screen dance I saw, the dancers leap through sheets of fire in a big abandoned building.
Of course, the building wasn't really on fire.
A technique called super-imposing was used.
The dancers were filmed and later, in the editing room. The fire was added to the background.
That sounds awesome. But if anyone can watch a dance on a computer screen, why would they pay to go see a live performance?
What if screen dance got so popular that it replaced live dance?
Screen dance is an entirely different type of presentation.
It could never replicate the immediacy, the kind of drama that live performance offers.
There will always be an audience for that.
I think what screen dance will do, though, is heighten awareness of dance in general.
Because it is a way... uh, it can reach people in their homes, in their workplaces, at anytime really.
And if someone discovers that they love dance by watching a screen dance, there's a good chance they will get interested enough to buy a ticket to see a live performance. "
L24C1
"Listen to a conversation between a student and a clerk in the bookstore.Hi. Can you tell me where to find New Kind of Science by, uh, by Stephen Wolfram?
OK.
Uh, I couldn't find it.
OK. Let me look it up on the computer for you.
Who would you say the author was?
It's a Stephen Wolfram.
OK. Let's see... Hmm... no, it's not coming up.
Hmm... I am not seeing it.
This is for a class at university here.
Yeah, It's assigned reading for a class I am taking.
It's for the semester, right?
You are not buying it in advance for next year or anything.
No, no. It's for a class I am taking now.
Hmm... Oh, oh, you know what? Um, it's for a graduate class.
Would that maybe make a difference? I mean...
I am an undergrad, but I am just taking this one class in the graduate department, so...
No, no. I don't think that's it.
That shouldn't make any difference.
But, hmm... let me see... maybe it's just... it could be that whoever entered it misspelled the title or the author's name, so I can't find it on the computer and I can't tell if it's sold out.
But if it's sold out, we would probably be getting a new shipment within about a week or so.
Ok. Well, I was hoping to get it sooner because like we already have assignments and you know, I mean, I guess I can get it from the library.
Right, of course.
But I am trying to check.
If we've ordered more, then that back orders information should be in the computer too.
Let's see... back order... Wolfram, Stephen... no, I am not seeing it.
I am sorry. We just don't seem to carry it.
Uh-huh. This is odd though.
What is... what's your professor's name?
I could try searching for his or her classes in the database.
That might help.
Um... OK. It's professor Kayne.
K-A-N-E?
No. It's professor Kayne, K-A-Y-N-E. He's in the computer science department.
Oh. It's for a computer science course, is it?
Yeah.
Well, that must be it.
Computer science books are sold across the street in the computer store.
Oh. Are there signs up anywhere?
I don't know.
Maybe they should put some up.
It could have saved us both some time.
Yeah. Well, anyway, I'll bet that's the problem.
Check across the street.
I'll bet they have it. But if not, come back, and I'll help you find it somewhere else.
I can call around to see if other bookstores might have it. OK?
OK. Thanks a lot. Bye.
Bye. "
L24L1
"Listen to part of a lecture in a Biology class.OK. For today, let's look at a reptile, a predator that hasn't evolved much in the last seventy million years.
No discussion of reptiles would be complete without some mention of crocodiles.
Now, we tend to think of crocodiles as, uh, kind of solitary, hiding out in a swamp, uh, kind of mysterious creatures.
But we are finding out that they aren't as isolated as they seem.
In fact, crocodiles interact with each other in a variety of ways.
One way is with vocalizations, you know, sounds generated by the animal.
This is true of the whole crocodile family, which includes crocodiles themselves, alligators, etc.
Take American alligators.
If you were to go to a swamp during the breeding season, you'd hear a chorus of sounds, deep grunts, hisses.
These are sounds that male alligators make, and some of them are powerful enough to make the water vibrate.
This sends a strong, go-away message to the other males.
So the alligator can focus on sending other sound waves through the water, sound waves that you and I couldn't even hear since they are at such low frequency.
But they do reach the female alligator, who then goes to find and mate with the male.
Vocalization is um... well, it is used for other reasons, like getting attention or just, um... letting others know you are distressed.
Let's see. New-born crocodiles, or hatchlings and their interactions with their mothers.
When they are born, croc... baby crocodiles have a sort of muffled cry while they are in their nest.
Hatchlings are really vulnerable, especially to birds and small mammals when they are born.
But their mother, who has been keeping vigil nearby, hears their cry for help and carries them to safety, meaning, to water.
So she takes them out of the nest.
Uh, uh, all the eggs hatched at once, so she has about forty newborns to look after.
Well, she takes about fifteen out of the nest at a time, carrying them in her mouth to the nearby water.
While she is taking one load of hatchlings, the others wait for her to come back.
But do you think they are quiet about it?
No way. They are clamoring for the mother's attention, sort of squeaking and practically saying ""don't forget about me!""
I heard some great examples of this on the television program on crocodiles last week. Anyone catch it?
It had a few interesting bits. But you know, uh, you have to be careful, think critically.
Sometimes I don't know where these shows find their experts.
Excuse me. But, um... does all that crying defeat the purpose?
I mean, doesn't it attract more predators?
Hmm...good question.
I guess, I am guessing that once the babies have the mother's attention, they are safe.
She's never too far away, and, and I think...
I mean, would you mess with a mother crocodile?
So after the mother transports all the youngsters, they still call to each other, and to their mother.
This communication continues right through to adulthood.
Crocodiles have about eighteen different sounds that they can make.
There's... um... um... you have deep grunting sounds, hisses, growls, squeaks and roars.
So there are many different sounds to interact or send messages.
This is more typical of mammals than of reptiles, I mean, crocodiles' brains are the most developed of any reptile.
In that sense, they are closer to mammals' brains than other reptiles' brains.
And we know that mammals, dogs for example, dogs vocalize many different sounds.
Crocodiles have a similar level of, uh, vocal sophistication, if you will, which makes them unique among reptiles.
Another thing would be, um, if a hatchling gets separated from the rest of its family, once the others get far enough away, its survival instinct kicks in.
It will make a loud distress call, which its siblings answer.
It calls again, and they continue calling back and forth until they all find each other again.
Another thing, something that wasn't on that TV show I mentioned.
Um... mother crocodiles lead their young from one area to another, like when they have to find a different source of water.
Usually she will lead them at night, when it is safer for them, moving ahead and then letting out calls of reassurance so that they will follow her.
Her voice helps give the babies the courage they need to leave the area and go some place that's a more desirable home for them. "
L24L2
"Listen to part of a lecture in a dance history class.As we have been studying, ballet, the classical ballet, is based on formalized movements, specific positioning of the arms, feet and the body.
So, now let's move on to modern dance, also known as theatrical dance.
Modern dance evolved in the late nineteenth, early twentieth century, and in most cases, audiences were very receptive to this radical new type of performing art.
Um... what made modern dance so radical?
Well, for example, I think the best analogy to modern dance is modern art or modern music.
Compared to their classical predecessors, these newer art forms are freer, more experimental, more improvisational.
Modern dance seeks to show how deep emotions and the music itself, how these intangible attributes can affect and inspire physical movement, and how movement can convey emotions to the audience.
As I said, in classical ballet, emotions are conveyed through a set of strictly formalized movements.
Now, a pioneer of modern dance was Isadora Duncan, who was born in 1878.
Isadora Duncan did study ballet briefly as a child, but she quickly developed her own unique style, which she called free dance.
And by age fourteen, she was teaching her free dance to young children and giving recitals.
Her early dance technique was loosely based on the natural movements of children, running, skipping, acting out stories, also on motions from nature, waves crashing onto shore, trees swaying in the wind.
Her expressive gestures were motivated from within rather than from being dictated by strict technique.
Duncan also wore her hair down, ballerinas typically wear their hair in a tight bun behind the head.
And instead of the short stiff skirts and rigid toeshoes worn by ballerinas, Duncan wore loose, flowing tunics, and she dance bare foot.
Now, that was something her audiences had never seen before.
Duncan performed in Paris and other European cities, dancing to the music of classical composers, but avoiding set movements and steps, no two performances were alike.
And audiences, for the most part, adored her.
In 1904, she opened a school of modern dance in Berlin.
And the next year she performed in Russia.
But the Russian critics were not really kind.
Some said Duncan's art form was closer to pantomime than to dance.
But her style was a clear rebellion against ballet, and ballet is extremely important in Russia.
A question, Julie?
Yeah. What did Duncan have against ballet? I mean, she studied it as a child.
As a youngster, she may have found it too restrictive, uh, not creative enough.
I think that feeling is exemplified by something that happened earlier in her career, in Russia.
Duncan attended a ballet, and the lead dancer was the renowned Russian ballerina, Ana Pavlova.
The following day, Pavlova invited Duncan to watch her practice.
Duncan accepted but was appalled by what she saw.
To her, the exercises that Pavlova and the other ballerinas were doing seemed painful, even harmful, standing on tiptoe for hours, moving their bodies in unnatural ways.
After seeing this, Duncan publicly denounced ballet as a form of acrobatics, uh, complicated and excruciating mechanism she called it.
This critic generated I think some undue rivalry between ballet and modern dance, and it would take a long time, many years in fact, for the rivalry to calm down. "
L24C2
"Listen to a conversation between a student and his geography professor.Hi. Professor Brown.
Hi. Paul. What can I do for you?
I have a question about the final exam.
I mean, will it cover everything we've done all term?
Or just what we've been doing since the mid-term exam.
Everything we've done all term.
Oh, boy. You know, I am still not too clear about the hydrologic cycle, um, the transfer of water back and forth between the earth and the atmosphere.
I really blew the question about it on the mid-term exam.
I want to do better on the final exam.
But I am still having trouble with it.
Well, uh, have you been to the tutoring center?
No, not for geography anyway.
Isn't that just for when you need help with writing, like an essay or a research paper.
Oh, no, you can get tutoring in a lot of subjects.
Some graduate students from this department tutor there.
That's good to know.
But I hardly go there because I have a part-time job.
I never seem to be free when they are open.
Well, they will be extending their hours when final exams begin.
You might try then.
But um... Well, since you are here now, can I help you with something?
Well, the hydrologic cycle.
I remember we went over a diagram in class.
And from what I remember, water changes back and forth from water in lakes and oceans to vapor, and then back to water again when it falls as rain or snow, as precipitation.
It's constantly being recycled through evaporation and condensation.
That's it. Basically.
Um... so exactly what is it you don't understand?
OK. I guess what I am really confused about is how the topography of the land, the mountains and valleys and stuff, affects precipitation.
OK. Good question.
Precipitation is influenced by topography among other things.
Um, why don't we talk about lake-effect snow?
It's a phenomenon that occurs anywhere you have a large lake that doesn't freeze and has cold air flowing over it, mostly in the Northern Hemisphere.
Like the great lakes in the United States?
Yes. What happens is that the cold arctic air blows across the lake from the north in winter.
And as the air crosses the lake, the lower layer is warmed by the lake water, which is much warmer than the arctic air.
And as this air is warmed and picks up moisture, it becomes lighter than the air above it.
So it starts to rise, right?
Yes. And clouds begin to form.
When the air gets closer to the shore, it's slowed down by the land and starts to pile up.
So it rises even faster because it has nowhere else to go, that's where topography comes into the picture.
And then it snows because as the air rises, it cools off and loses its capacity to hold water vapor.
That's right.
OK. Thanks. Any chance you'll ask this question on the final?
I don't know yet.
But you seem to have a handle on it. "
L24L3
"Listen to part of lecture in an archeology class.Between 11000 - 10000 B.C.E., North America was populated by a wide variety of great beasts, like mammoth, and mastodons, both elephant-like creatures with big tusks, and camels, giant slots, the list goes on.
By about 10000 B.C.E., all those giant creatures, the Megfauna of North America were gone.
We do not know exactly what happened to them, but there are some theories.
One theory is that they were hunted to extinction by humans.
The humans who coexist with these giant species in North America at that time were what we today called the Clovis people.
And there is a Clovis site in a valley in Southern California where the remains of thirteen mammoths were found.
And spear points, tools for processing meat, and fire places.
That would appear to be some pretty compelling evidence.
Mammoth bones have also been found at some other Clovis sites.
But then at other Clevis sites, there is also a lot of evidence that the Clevis people mostly gather plants and hunted small games, like rabbits and wild turkeys.
Also there are several places in North America Where you have natural accumulations of mammoth bones that looks very similar to the accumulations at the Clevis site, except there is no human debris, where the mammoth almost certainly died as a result of some kind of natural disaster.
So I think it is quite likely that those 13 mammoth in Southern California also died of nature causes, and that Clevis people simply took advantage of the situation.
Um... OK. That is the hunting theory.
Now let's look at another theory, uh, an alternative to the hunting theory, the climate change theory.
At around of 11500 B.C.E., the world was coming out of the ice age.
And with that came increased seasonality, that is, the summers became warmer, and the winters actually became colder.
This extreme shifts would have put a lot of stress on the bodies of animals that were used to a more moderate range of temperatures.
But the most important impact of this increased seasonality may very well have been its effect on the distribution of plants.
Today we take for granted that there are horizontal bands of plant communities.
In the far north, it is tundra, which gives way to the forest as you move southward.
And even farther south, grasslands take over.
But during the ice age, these plant communities actually grew together, mixed with one another.
So ice age animals had access to many different types of plants, different types of food.
But when the seasons became more distinct, the plant communities were pulled apart, that meant, that in any given area, there was less plant diversity.
And as a result, so the theory goes, the Ice Age animals that depended on plants diversity couldn't survive.
And the greatest beasts were the ones that needed the most diversity in their diet.
Again, we have what at first seems like a pretty attractive theory, but then, how do you explain the fact that this has happened before?
You know, global cooling followed by global warming, and there was no extinction then.
Uh, you know, I recently read an interesting article about an archeologist who tried to solve this puzzle with the help of his computer.
What he did was, he wrote a computer program to simulate what would happen to mammoth under certain conditions.
Em, say for example, there is a drought for a couple of decades, or hunters are killing of 5 percent of the population and so on.
One thing he found was that humans did not necessarily have to kill these animals in great numbers in order to nudge them toward the extinction.
That's because very large animals have a slow rate of reproduction, so all you have to do is remove a few young females from the herds and you can, fairly quickly, significantly reduce the population.
And then he came up with a scenario that combined some hunting by humans with some environmental stress, and... bang.
The simulated mammoth were extinct within decades.
So it seems the mixture of hunting and climate change is a likely scenario.
Uh, Of course, computer simulations are not a substitute for hard evidence. "
L24L4
"Listen to part of the lecture in the Astronomy class.Um, many people have been fascinated about Venus for centuries because of its thick cloud cover, this so-called ""planet of mystery and all of that"".
Well what's under those clouds? What's the surface of the planet like?
Some questions about the surface are still unresolved, but we have learned a lot about it in past several years.
First of all, let me talk about how we've been able to get pasted those clouds.
First, there were Soviet modules that landed directly on the surface, and sent back some images of what was around them.
Second, we did some radar imaging from satellites from above.
Radar can get through the clouds.
So what have we learned?
Yes, Karen.
Well, I remember reading that there is not really a lot going on, that the surface of Venus is just flat and smooth in a lot of places.
Um, yeah, it's smooth in a lot of places but that's not, um, that's not the whole picture.
In other areas, you've got canyons, ripped valleys, meteor craters, uh, lava domes, these lava formations that look like giant pancakes, and also volcanoes.
Well, one of the most interesting features on the surface are in fact, the shield volcanoes.
Shield volcanoes formed when magma comes out of the ground, in the same spot over and over again.
Remember, magma is hot molten rock that's underground, and it's called lava when it reaches the surface.
Uh, so the lava builds up and hardens and a volcano forms.
Now the lava on Venus is thin, it spreads out easily.
So shield volcanoes have very gentle sloping sides.
They are called ""shield volcanoes"" because viewed from above, they kind of resemble shields, you know, like a warriors' shield.
But what's particularly interesting about these volcanoes is that most of the volcanoes here on Earth are not shield volcanoes.
Instead, they are other volcano types like strata volcanoes for example, which are the result of tectonic plate movement.
Remember tectonic plates?
Underneath the Earth's crust, there are a number of the shifting slabs or plates that are slowly moving.
And in the zones on the edges of the plates where different plates meet and interact, that's what we get most of the Earth's volcanoes.
On Venus, however, volcanoes are not clustered in discrete zones like they are on the Earth.
Instead, they are more or less randomly scattered over the Venus' surface.
Well, that's significant.
Venus has mostly shield volcanoes, and they are randomly scattered that indicates that Venus doesn't have moving tectonic plates, and that's a big difference compared to the Earth.
Here on Earth, moving tectonic plates are a major geological elements,just crucial for the whole surface dynamics, right?
So why doesn't the Venus have them?
Well, there are a few theories.
Um, one of them is that this has to do with the fact that Venus has no surface water that's needed to kind of lubricate the movement of the plates, you know, like oceans on Earth.
Yeah, I forgot to spell that out, Venus has no surface water.
Wait a second.
Did you say we have the shield volcanoes on Earth? Can you give us an example?
Sure, the volcanos on the Hawaii islands in the Pacific Ocean are the shield volcanoes.
They are formed over a hot spot magma.
So while on Earth's we have several types of volcanoes, on Venus, there is mostly the one type.
Uh, Eric?
Are the volcanoes on the Venus still active?
Well, that's an interesting question.
There is still some discussion on that point, but here is what we do now.
First, the level of sulfur dioxide gas above Venus's clouds shows large and very frequent fluctuations.
It's quite possible that these fluctuations, the huge increase and decrease of sulfur dioxide happening again and again.
It's quite possible that this is due to volcanic eruptions, because volcanic eruptions often emit gases.
If that's the case, volcanism could very well be the root cause of Venus's thick cloud cover.
And also we have observed bursts of radio energy from the planet's surface.
These bursts are similar to what we see when volcanos erupt on the Earth.
So this two suggests ongoing volcanic activity.
But although this is an intriguing evidence, no one has actually observed a Venus' volcano erupting yet, so we can't be positive. "
L25C1
"Listen to a conversation between a student and his academic advisor.Hi Mark, what can I do for you?
I'm just filling out this approval for graduation form for the Dean's office and...
I don't know, I hope I will be able to graduate next semester.
Well, as long as you've met the departmental requirements and you submit the form on time, you shouldn't have any problem.
Make sure you include all the classes you will have taken for your degree in finance and the electives too.
Yeah, but as I look over the form, I got confused because the way, uh, they've changed the requirements, so, now I'm not sure i will be qualified to graduate next semester.
I know I would before, under the old requirements.
Well, when the business department changed the curriculum to include more courses in international business to .....well, because of the increasing globalization of business, we made sure that students would finish to their second year, that is those who were in their third or fourth year wouldn't be affected.
The new rules only apply to students in their first or second year.
Oh, that's good to know.
Uh, the departments are hiring new faculty too, I heard, to teach some of the new courses?
But, I want to...
Yes, one new faculty member has been hired.
She'll be teaching International Banking as a matter of fact.
Actually, that's what I wanted to ask about, International Banking.
I took International Banking 1, but I never took International Banking 2.
It used to be that the second semester of International Banking was an elective, but now it says it's a required class.
Yes, but that's one of the recent changes, so...
Oh, oh, okay.
Oh, and I am planning to take a management course next semester but I don't know if it's, if it will count toward my major.
What's the course?
Organizational behavior.
Yes, that'll count toward your major, that's a difficult class you know, but well worth it.
So it looks like you'll have all the required classes you need, you should be just fine.
Uh, I assume you've taken a seminar?
Yeah, I took the marketing seminar.
Ok, you're looking good.
Just to be on the safe side, why don't you talk to someone in the Dean's office before you give them the form?
Ok, so should I just explain to them that even though one of these classes got changed from an elective to a required class I don't have to take it?
Yes, you've met the requirements for graduation, and if there's something I need to do, if, if I need to write a letter or whatever, just let me know.
Ok, thanks. I'll let you know if I need that letter. "
L25L1
"Listen to a part of a lecture in a conservation biology class.One consequence of global warming is extinction, there is compelling evidence that global warming will be a significant driver of many plant and animal extinctions in this century.
So we are considering various strategies to help some threatened species survive this unprecedented, this warming trend which, as you know, is caused mainly by green houses gases produced by the burning of fossil fuels.
The most radical strategy being debated among conservation biologists is Assisted migration.
Assisted migration means picking up members of the species or members of a group of interdependent species and physically moving or translocating them.
Translocating threatened species to a cooler place to higher latitudes or higher elevations for example.
Now migrations are natural survival strategy.
Over the past two million years, colder glacial periods have alternated with warmer inter-glacial periods.
And so in response to this gradual climatic swings, some species have shifted their ranges hundreds of kilometres.
So perhaps you are wondering why not let nature take its course now.
Well we can't.
The main problem is today's fragmented habitats.
During previous inter-glacial periods, when glaciers were retreated they left behind open land in their wakes.
Today human development has paved over much of the natural world.
Ecosystems are fragmented, housing developments, highways, and cities have replaced or sliced through forests and prairies.
There are few corridors left for species to migrate through without help.
So conservationists are trying to save as many species as possible.
Now, assisted migration could become a viable part of our rescue strategy, but there are a number of uncertainties and risks.
Without more research we can't predict if assisted migration will work for any given species.
A translocated species could die out from lack of food for example.
At the other extreme, we might successfully translocate the species but within five or ten years, that species could proliferate and become an invasive species.
Like a non-native plant that chokes out native plants by hogging the nutrients in the soil.
Translocated animals can become invasive too.
It happened in Australia.
The cane toad was introduced back in 1935 to control an insect pest that was destroying Australia sugar cane plantations.
But the cane toad itself became a pest and it destroyed much of the wild life on that continent.
Also, many species are interdependent, intimately connected to one another.
Like animals that eat a certain plant and that plant relies on a certain fungus to help it get nutrients from soil.
And on a certain insect for pollination, we probably have to translocate entire networks of species.
And it's hard to know where to draw the line.
And in addition to all that it's not even cleared that the assisted migration or any migration for that matter will help at least for some species.
Earth was already at one of its warm inter-glacial periods when we started burning fossil fuels.
And in the 21st century, global temperatures are expected to rise two to six degrees.
That rate of heating is far greater than during the last glacial retreat some twelve thousand years ago.
Um... whether to use the assisted migration, this debate is mostly within the biology community right now.
But the ultimate decision makers, in United States at least, will be the government agencies that manage natural resources.
Assisted migration really needs this level of oversight and soon currently there is no public policy on using assisted migration to help species survive climate change.
People aren't even required to seek permits to move plants or invertebrate animals around as long as they are not classified as pests.
In one case, a group of conservationists has already taken it upon itself to try on their own to save the endangered tree, the Florida Torreya tree through assisted migration.
There is only about a thousand individual Florida Torreyas left and global warming is expected to significantly reduce or eliminate this tree's habitat.
So this conservation group wants to translocate seedlings, Florida Torreya seedlings, 500 kilometres north, in order to expand the species' range.
The group believes that its effort is justified, but I and many other biologists will be watching very closely how this maverick group makes out because, like I said there could be unintended consequences. "
L25L2
"Listen to part of a lecture in a music history class.So, I just finish reviewing your papers on the influence of nationalism on the composers' music.
And initially, I was surprised that none of you chose to write about Bella Bartok.
That is until I remembered that we haven't had a chance to discuss him in the class yet.
He was a wonderful and ground-breaking composer.
Bella Bartok was a Hungarian whose life stretched from the late 19th century to the middle of 20th century.
But he was not a fan of the romantic style of music that was popular in his homeland during his youth.
Wait, Hungary wasn't a country in 1900s, was it?
You're right, I should have been clear.
Bartok was born in Austria-Hungary, a nation that broke apart when he was 40 years old.
Actually the town where he was born is presently part of Romania.
The political history of that region is complex.
Suffice to say Bartok is generally known as a Hungarian composer.
So, during Bartok's youth, the music played in the concert halls of the Austria-Hungary was dominated by romantic pieces by mostly German composers.
We discussed the romantic style last week.
These pieces were long and lyrical. They were meant to have a sort of grandeur about them.
And in the early 1900s,composers who worked in the romantic style were the most popular in Austria-Hungary.
But Bartok, he was part of the musical community that was trying to change this.
And it led him to, well, the first thing it did was lead him to travel.
He looked to the countryside for the music of the farmers and the people who lived in the small towns.
And their music, well, you can say he discovered the music that was popular in those areas.
What do you mean?
Well, all the music we've been talking about the past few weeks it really was all in the cities.
That's where the composers and the orchestras were.
Out in remote areas of the countryside in rural locations, music was more traditional.
The same song was enjoyed by previous generations.
Bartok went out, he travelled to a significant portion of eastern Europe actually.
He roamed the countryside and listened to the music heard in the small towns and in all sorts of celebrations.
He attended weddings, dances and religious ceremonis where he heard a very different sort of music from the romantic stuff being played in the concert halls in the cities.
The music he heard is what we were considered folk music.
And any of those same songs played in the concert halls?
No. At first, he went around to document the folk music.
He really wanted to make sure that folk songs were written down before they disappeared.
In fact, Bartok didn't start out the trip thinking of himself as a composer.
He was an ethnomusicologist, and he studied the traditional music of the region.
But it turns out that what would later have a notable influence on the European music on the whole, was the way Bartok used the elements he heard in folk songs in his own compositions.
He adopted a number of elements from what he heard, like unusual rhythms and he liked to use glissando as his hallmark, which you probably got from listening to Croatian folk music.
A glissando is... well, I've got a recording of Bartok here.
Let's wait until the music is fresh in our minds.
Susie, do you have something you want to ask first?
Yeah. Before, you mentioned nationalism, and...
Ah, right! Yes. When Bartok had his new pieces performed, their folk music roots made them instantly popular.
It happened to be a time of strong nationalism in Austria-Hungary.
So his composition came just at the right time. It became very successful there.
Particularly, when Bartok's ballet The Wooden Prince opened, there was great excitement for music that included musical elements from local folk songs, music that reflected the region's musical traditions.
However, as popular as Bartok was in his homeland, he did not get much international recognition during his lifetime. "
L25C2
"Listen to a conversation between a student and his biology professor.Well, you know, I'm reading the papers about whales, and the path they travel as they swim through the ocean, their migration patterns.
Yes, I remember.
Well, I was thinking about it, and I realized I don't understand how they hold their breaths under water.
It's a little crazy for me to be writing a paper about migration patterns without actually knowing how they stay underwater for so long.
Did you do any research to find out how they do it?
Yeah, I did. I searched on the Internet, and there was a lot of information about whales, their habitats, the way they communicate, you know, their songs.
But if there was anything about whales and how they hold their breaths, I missed it.
I've got a bunch of books.
Actually, I've got so much information. It's a little overwhelming.
I'm surprised that there is nothing about it in any of those books.
Well, to be honest, I've only skimmed them so far.
I'm still working on finding sources.
Ok, I know I encourage everyone in class to look at a substantial number of sources, but I don't want you to get overwhelmed.
Looking at a number of sources gives you a good knowledge base, but students only have a limited amount of time to work on each paper.
I don't expect you to read a dozen of books on whales for this assignment.
Focus on just a few.
Ok, thanks.
You know, since you're already here, I can give you a quick summary of how whales hold their breaths underwater.
It's just a matter of certain adaptations in their anatomies, specifically in their circulatory system.
So, the blood flow was what makes the difference?
Yes, and in a couple of ways.
First, blood makes up a larger share of whale's weight than any other mammals.
So they can store more oxygen because they have more blood?
Yes, but that's only part of it.
They also have a greater capacity than land animals to store oxygen in their blood.
So how does having more oxygen in their blood help them stay underwater longer?
It's the way the whale's blood carries oxygen to the rest of its body.
Whales carefully conserve their oxygen when underwater in a couple of ways.
When a whale dives, its metabolic weight drops, causing its heart beat to slow down.
And the blood flows to its muscles and some of its none-vital organs, like its kidneys, is also cut off.
A Whale's muscles and none-vital organs are able to function without oxygen for an extended period of time.
I see, well, now I can concentrate on my topic. "
L25L3
"Listen to part of lecture in the history class.The professor has been discussing Egyptian hieroglyphs.
Egyptian hieroglyphs are the ancient Egyptian writings, found in ancient Egypt on walls, monuments, and on the inside and outside of the temples.
Hieroglyphic writing ended abruptly about 1600 years ago, and it mystified the most brilliant minds in the study of the Egyptian artifacts and archeology for many many centuries.
Finally, the possibility of deciphering hieroglyphs came about with the discovery in 1799 of the Rosetta stone.
The Rosetta stone is arguably the most famous archeological artifact ever discovered.
It contains the same exact text written in three different alphabets: Greek, demotic and hieroglyphic.
But we didn't even know at first, that the three texts on the Rosetta stone contain the same information.
And two of the three alphabets are ancient Egyptian scripts that stop being used, the hieroglyphic and the demotic.
The demotic script found on the Rosetta stone, um... well, demotic was not as elaborate as the hieroglyphic writing.
It was used for more mundane matters or like administrative documents.
These ancient Egyptian scripts were replaced by Coptic script, but eventually the Arabic language replaced the Coptic, and this cut off the linguistic link between ancient and modern Egypt.
Now the Rosetta stone was remarkable, because as I said,on it,was the same text in three different alphabets: Greek, demotic and hieroglyphic.
The stone was essentially the dictionary that the scholars needed to interpret the meaning of hieroglyphs, and it took a uniquely equipped researcher to finally decipher and understand what was written on the stone.
Thomas Yang, an English scholar, was the first to seriously attempt to decipher the symbols on the Rosetta stone.
He suspected rightly, that the hieroglyphs were phonetic symbols, that they represented sounds rather than pictures.
Until then, all scholars assumed that the hieroglyphs were pictographs, that they symbolize objects or concepts.
Thomas Yang focused his attention on one set of hieroglyphs that he thought would probably spell out a single word, the name of a king or queen.
He guessed that the symbols represented the name of the earlier Egyptian ruler Ptolemy, since Ptolemy was also written in Greek on the stone and was indeed a Greek name.
And Yang, did actually prove that these hieroglyphs represented sounds rather than whole words.
Strangely though, he gave in to the dominant thesis of the day that hieroglyphs were pictographs.
He actually dismissed his own finding, as an anomaly, because the Ptolemy dynasty was Greek, not Egyptian.
In other words, he figured that it was an exception to the rule.
It was phonetic because it was Greek not Egyptian.
How else could an Egyptian depict a Greek name other than spell it out?
And that brings us to the hero of our story, Jean-Francois Champollion.
Champollion built on Yang's work, showing that different hieroglyphs spell the name of the kings or queens like Alexander or Cleopatra.
But his critics noted that this was still not traditional Egyptian names.
He hadn't done any more than Yang had been able to do, so he couldn't disprove the dominant theory.
Then, in 1822, Champollion was shown a set of hieroglyphs that contain traditional Egyptian names.
The first two of the symbols were unknown, but Champollion knew that the repeated hieroglyphs to the far right symbolized an ""S"" sound.
He then drew on his linguistic knowledge to arrive at the solution to the problem.
You see, unlike the any of other scholars who have tried to crack the code, Champollion happened to be fluent in Coptic.
He wondered and this was the real breakthrough, if the Coptic was the language that symbolized by the hieroglyphs on Rosetta stone, and if so, then perhaps that first this shape symbol might represent the sun.
And the Coptic word for sun is ""ra"".
See where this is headed, so if the symbol were Coptic, the first symbol would be ""ra"".
And then, an unknown symbol followed by a double ""S"" sound, was this, Champollion wondered, the name ""Ramses"".
He was eventually able to confirm that it was.
So, he had figured it out. Hieroglyphs were mainly phonetic, they represented sounds not pictures, and the underlying language was Coptic.
A lot of work remained, but champollion had cracked the code. "
L25L4
"Listen to part of a lecture in an animal behavior class.All right, I hope you all had a chance to finish the assigned readings about animal play, because I want to spend some time discussing the different viewpoints presented in those articles.
Let's start with the play-as-preparation hypothesis.
Jerry, can you explain it?
Yeah, play-as-preparation. The young animals play in order to get really good at certain specific things they'll need to do when they are adults, things like chasing, pouncing, climbing.
In other words, they play in order to practice survival skills, like movements used in hunting and fighting.
That hypothesis makes a lot of sense, like, maybe the most sense of all the theories we read about.
And, what leads you to that conclusion?
Well, like wolves, the young pups, they fight a lot and bite, you know, not to hurt each other, but, just seems obvious why those wolf pups play like that, give them practice with skills that'll make them better hunters or fighters as adults.
Oh, I don't know about that, I mean, some of the things the young animal does while playing are totally different from the things they will do as an adult.
There was a really good example in second article. I can't remember what it is called exactly.. uh... self...
Self-handicapping?
RIGHT! Self-handicapping, like during the fake fight... uh... a play fight, if one of the animals is winning, the winning animal might just stop and give up its advantage.
Yes, and often a shift to a submissive posture, too.
Of course self-handicapping hardly ever happens in a real fight, because in a real fight, well, the point is to win.
So this self-handicapping is important to take this into account before just deciding to go with that first explanation.
And in fact, there really isn't much in the way of solid experimental evidence to support the play-as-preparation hypothesis.
What about the other one, the flexibility hypothesis?
Ah, yes. Let's talk about that.
As you say, play is much more than just pretend fighting or practicing other adult behaviors.
Apparently, it also contributes to the development of a brain that's flexible.
A brain that's quickly able to get a handle on unfamiliar situations.
This notion, the flexibility hypothesis, well, many of my colleagues find it quite persuasive.
So like, with kids, a little kid might play a game with a friend, and then they might race each other across the field, so, they are switching from one type of play to another, there's a lot of variety?
I mean, they are learning to response to whatever happens?
Well, that's the general idea. But let's hold off on talking about human behaviors from now.
OK, according to the flexibility hypothesis, yes, the diversity, the variety in play can lead to a broader behavioral vocabulary.
A broader behavioral vocabulary?
Can you explain what that means?
Well, sometimes play results in an animal doing something it would not normally do, that can lead to the animal learning to adapt, to come up with new behaviors that can help it cope with major problems later on, like staying safe or finding food.
Yeah, and there was that brain study you had us read about, too.
Oh, the one on how play affects development within the brain?
Right, that's it. About the animals raised in an environment where they did not get opportunities to play?
Yes, wasn't the conclusion interesting?
That play literally stimulates growth creates connections within the brain?
We need to do further studies, but...
Excuse me. Can we go back to play fighting for a minute?
I'm wondering, can the flexibility hypothesis really explain that?
Play fighting? Actually that's something that flexibility hypothesis explains very well.
Since play fighting includes variations in speed and intensity, and quick role reversals involved with self-handicapping, and animal that's play-fighting is constantly responding to changes.
So it's learning to be flexible. "
L26C1
"Listen to a conversation between a student and a university print shop employee.Hi, I saw your ad in the campus newspaper.
Oh. We don't have any job openings right now.
Oh no. I meant the other ad about the services you provide for students.
You see, I have been working at the campus tutoring center as a maths tutor.
But things have changed, including my schedule.
And now I want to start doing tutoring work independently.
But in order to, basically, start my own business, I need to get the word out.
Ok.
I was thinking I should get something printed up that I can hand out to people.
Ah. Well, actually, I just printed up some great-looking flyers for someone doing the same thing.
Flyers. Yeah, that's an idea.
I guess then I could post them around campus.
Yeah. And you can hand them out too.
But, oh, you know what?
I did something really neat for someone last week.
She didn't want to go the traditional route, you know, business cards, flyers, so we customized pencils for her.
Pencils?
Yeah. You know, a little message printed on the pencil.
Oh, that's cool.
Yeah. But you should know, it's not our cheapest option.
Oh, and you know those little sticky notes?
You do those too.
Well, we did once.
I think those bright pieces of paper would be real attention getters.
You know, students use them all the time, so they should be good for business.
I don't know why we haven't done more.
Wow.
So you've got some options.
Right. Well, what about business cards?
My friend has these business cards, she does tutoring too.
And she got them at this place in town, but they were kind of expensive.
For business card?
Well, I don't know what your friend paid, but we could do something real simple and it wouldn't be much.
Like for a batch of 250 for one of our standard designs, 20 dollars maybe.
20 dollars sounds okay.
Now, there are some other choices that will affect the cost.
You know, like different background patterns, using colour ink, that sort of thing.
And it also depends on how many words you want to include.
Ok. Well, I know what I want them to say.
But I am just thinking, I kind of like that pencil idea.
Yeah. I thought it was neat.
Now, of course you can only fit your name and phone number, and like, in your case, maths tutoring on it.
Right. Well, I could custom design the business cards though right?
That's what my friend did.
She said she designed them at the computer right there at the print shop.
Well, you can do that here, too.
But a custom design would be a bigger investment for your business than one of our standard designs.
Well, I don't know.
I am interested in business cards, so can I look at the standard design? "
L26L1
"Listen to part of a lecture in an advertising class.Last class someone asked about green marketing.
Green marketing refers to companies promoting the product as environmentally friendly.
Companies often turn to advertising experts to help them do this.
Green marketing seems recent, but advertising professionals grew interest in it several decades ago.
The seeds for green marketing were probably planted in 1970, when the first Earth Day took place.
Rallies all over the United States were organized to protest environmental degradation.
Some 20 million demonstrators participated in that first earth day.
And it helped spark dozens of environmental laws.
The biggest was the Endangered Species Act of 1973, which protects imperiled animal species from extinction.
There was also passage of the Clean Water Act and the Clean Air Act was strengthened.
Earth day, environmental laws, environmental issues in the news, being green was entering the mainstream.
And businesses started saying, hey, we can get involved in this.
So in 1975, a major advertising trade group held its first workshop on ecological marketing.
A few years later, we began seeing ads tapping into people's environmental concerns.
But as some green marketers learned the hard way, green marketing must still involve all the same principles of a traditional marketing campaign.
Your ad must attract attention, stimulate consumer's interest, create a desire for your product, and motivate people to take action, to buy your product.
So let me tell you about one green marketing campaign that failed at first and explain why.
It was for a compact fluorescent light bulb.
We'll call it the eco-light.
It was first introduced, I believe, in the late 90s.
It cost far more than a regular incandescent bulb.
The advertising message was basically, use this eco-light and save the planet.
But that message wasn't effective.
Research shows that consumers don't want to let go of any traditional product attributes, like convenience, price and quality, even though surveys indicate that almost everybody cares about the environment.
So the company reintroduced the eco-light with a new message, one that emphasized cost savings, that the eco-light lowers electric bills and lasts for years.
So it's good for the Earth, cost-effective and convenient because it doesn't have to be changed every few months.
This ad campaign worked like a charm.
Something else, uh, the company that makes the eco-light, researchers would consider it an extreme green company, not only because its products are energy-efficient, but because the company tries to reduce its environmental impact in other ways too.
Like in addition to selling Earth-friendly products, its offices and factories are designed to conserve energy and use all sorts of recycled materials.
A company that only recycles office paper, researchers would classify as a ""lean green company"".
And there are other degrees of greenness in between.
So if your green marketing strategy's gonna work, your message should be valid on all dimensions.
When a company as a whole is credited for reducing its environmental impact, this can lead to brand loyalty.
People will come back and buy your product more and more.
However, let's say you're fined for violating the Clean Water Act while manufacturing products from recycled materials.
The public would eventually find out.
You can't just make the claim that a product is environmentally friendly and not follow through on. "
L26L2
"Listen to part of a lecture in a biology class.OK, Just before the end of the last class, we started talking about trace metals, metals found in living organisms in very small quantities that serve important biological and important nutritive function in these organisms.
And one trace metal that serves a nutritive function is zinc.
Zinc assists in a number of processes in humans, but we are going to focus on just one, one that applies to a number of organisms, not just humans.
See, zinc plays a major role in carbon cycling, the conversion of various kinds of molecules with carbon, like carbon dioxide into other kinds of molecules with carbon that organisms can use.
So, take respiration, our bodies - our cells produce carbon dioxide when they break down sugars.
We need to get CO2 out of our bodies, so the CO2 is converted into carbonic acid, which the blood is able to carry to the lungs.
Once the carbonic acid reaches the lungs, it's converted back into carbon dioxide, so that we can breathe it out.
Now, this whole conversion process relies on a particular enzyme.
Um, who remembers what an enzyme is? Bob?
Um, it's a protein, a specific kind of protein, one that speeds up chemical reactions.
Exactly, different enzyme assists in different chemical reactions.
Now, the one that speeds up the conversion of carbon dioxide has zinc in it.
So this zinc enzyme is critical for getting CO2 out of our bodies through the lungs.
And it's also extremely important for plants.
Bob, can you tell us why?
For making food, for photosynthesis?
Exactly! For photosynthesis.
Plants also convert carbon dioxide into different forms of carbon-containing molecules and the conversion process uses and relies on the very same enzyme that works in humans.
So, zinc is also important for plants.
OK, but zinc is scarce in certain environments, and it is particularly scarce in waters near the surfaces of rivers and lakes and shallower parts of oceans, which might make us wonder how plants could live there at all.
In fact there are a lot of marine plants that survive, that grow and reproduce in surface waters.
In particular, there are a lot of diatoms.
Diatoms are microscopic, photosynthetic organisms and they are a major source of food for other organisms in the ocean.
There are a number of different types of diatoms and, well, diatoms play a very important role in the carbon cycling process, because they help make carbon available to other organisms in deeper parts of the ocean.
The carbon that these diatoms use in photosynthesis is transferred to other parts of the ocean when the diatoms are eaten, say, by a fish that absorbs the carbon and then swims to another part of the ocean; or when the diatoms die and fall to the ocean floor.
So, how do diatoms survive if zinc is so scarce?
Well, recently researchers discovered that a specific type of diatom makes a different enzyme that serves the same purpose.
But this enzyme doesn't contain zinc.
Instead, this new enzyme incorporates another trace metal - cadmium.
Kelly, you've got a question?
Yeah, I thought cadmium was toxic, didn't you say that?
It is poisonous to humans. Um, actually, we used to think that it was toxic to all biological life, that it didn't serve any biological purpose.
But new study suggests that cadmium can actually substitute for zinc, that organism can use it instead of zinc when there is not enough zinc in their environment.
Now the discovery of this cadmium-based enzyme is really important for a number of reasons: it's actually the first enzyme we discovered that uses cadmium.
So it's possible that other not so typical trace metals may be used in chemical processes, that marine organisms might make enzymes from other trace metals when the essential one is scarce.
And there're maybe other types of diatoms that use cadmium to cycle carbon.
But there is something else to think about, what is one of the most common greenhouse gases in our atmosphere, one of the major culprits in global warming?
Carbon dioxide, right?
Now, if all these diatoms are taking carbon dioxide from the surface, converting it and transporting it to the bottom of the ocean, well maybe there's more to that whole process, that cycle, something that we overlooked.
So further research might tell us more about this warming cycles too. "
L26C2
"Listen to a conversation between a student and her biology professor.Hi, Jean, how was the... uh, the conference, right, the conference on volunteerism?
That's where you were last week.
Yeah. It was great.
I met a lot of people from some really amazing organizations that are working in the area.
Now it would be a lot easier to get students to volunteer in the community.
Plus, I have never been to any of the beaches here before.
Being at the beach was definitely a plus.
Well, I hope you had time to look over the notes from the class you missed.
You did get the notes, right?
Yup. I'll look them over before tomorrow's class.
Good. And let me know if you have any questions.
Well, there is something that I wanted to ask you now.
It's about something I noticed at the beach.
Oh, what's that?
Well, see, there are a lot of jellyfish there, floating in the water.
That couldn't have been pleasant.
Not for swimming.
But it was interesting.
I mean, the jellyfish were glowing, I swear they were.
And I am wondering what that's about.
Ah, glowing jellyfish.
That is interesting. Uh, it's called bioluminescence.
And actually we are going to talk about it later in the semester.
Basically, bioluminescence is light that's produced by a chemical reaction.
Really? Inside the jellyfish?
Well, not all jellyfish, about half of them.
Actually, a lot of marine organisms have this ability, especially in deeper parts of the ocean.
Oh, I get it.
Like the darker it gets, the more the fish needs light, right?
Well, bioluminescence serves a number of functions.
Most aquatic organisms use it for communication and for attracting prey.
But jellyfish usually use it as a defense against predators.
Some jellyfish produce bright flashes of light that confuse predators, to, uh, to startle them.
But jellyfish closer to the surface, probably like the jellyfish you saw, they use bioluminescence to hide.
The light they produce matches the color of the dim sunlight, so they blend in, and, uh, and predators can't see them.
Wow, really?
Well, I am looking for a topic for my term paper, so maybe I could do it on these glowing jellyfish.
That's why I wanted to ask you about them, you know, to find out if there was really something to write about.
It's a great topic.
But you'll have to make sure the topic is manageable.
Like I said, about half of all jellyfish are bioluminescent, so you may want to look at a particular type of jellyfish or several types that benefit form bioluminescence in the same way.
Or you could investigate current research on bioluminescence, on, on the chemical process, or...
Here's an idea.
You seem to be very involved in local issues.
See if you can identify the jellyfish you observed on the beach and how they fit into the local ecosystem.
Yeah, you know, some of the environmental groups I met last week might even be able to help me. "
L26L3
"Listen to part of a lecture in an astronomy class.OK. We've been looking at some of the smaller members of our solar system, comets.
You already know about the structure of comets.
Let's continue our discussion now by talking about orbits, especially those of the so-called periodic-orbit comets.
These are the comets that circle around the Sun pretty regularly.
They return again and again, predictably, after a certain period of time.
That's why we say their orbits are periodic.
Probably the most famous and brightest of these is Halley's comet.
Halley's comet comes from far out in the solar system, goes in close to the Sun, and then out again.
At its closest approach to the Sun, Halley's comet is about twice as close to the Sun as Earth is.
And at it's farthest, it's about thirty-five times farther from the Sun than we are, which puts it out beyond Neptune.
Basically, the idea here is that a periodic comet, with its very elongated orbit, just keeps coming back around again and again.
With Halley's comet, well, it returns every 75 years, roughly.
But where is Halley's comet during most of this time?
Well, like all orbiting bodies, a comet moves faster when it's closer to the Sun.
So it only spends about a year or two in our neighborhood, inside the orbit of Jupiter.
Most of its time is spent way out beyond Jupiter's orbit, poking along near the farther reaches of its own orbit.
Because of this, we can only see Halley's for a few months every 75 years, first on its way in toward the sun, and then on its way out again.
Now, you remember from our previous discussion that a comet's nucleus, its core, is made up of ice and dust, like a frozen snowball, and as it approaches the sun, it starts to heat up.
And some of the ice vaporize into gas and spreads out from the nucleus.
The gases that vaporize from the comet, the comet never collects them back again, so on every orbit, the comet leaves part of itself behind.
OK, how old is this solar system?
Four and a half billion years, remember?
And Halley's is going around the sun once every 75 years and losing stuff each time.
So the comet should be long gone by now, right?
I mean, how, come Halley's is still there?
After four and a half billion years, how could it be?
Well the answer is that this comet hasn't always been in such a short periodic orbit, since once a comet gets into an orbit that keeps it coming in close to the sun quite frequently.
Well, that comet's probably not going to be around too much longer.
So this kind of periodic orbit is only a phase in a comet's life.
A phase that just precedes its final breakup.
We've seen comets do that, going toward the sun and come back around, torn into pieces.
But lots of comets aren't like that.
They come in, pass behind the sun, and then travel back out.
But with an orbit so large, and its farthest point so far away from the sun that we just don't know how far out it goes.
We just can't determine that very accurately from the close in part of the orbit that we do see.
So these are often called parabolic-orbit comets.
Parabolic means the orbit is open at the far end.
Actually the orbit probably does close and return the comet to the vicinity of the sun eventually, but the period might be tens of thousands of years.
And basically, we can't determine it.
So we just, we refer to them as open-end parabolic-orbit comets.
So, what can change a comet with one of these long orbits where they only come by the sun occasionally into a much more frequent periodic visitor?
Well, gravitational interaction with planets, right?
If a comet on one of these long period orbit at some point comes close to Jupiter or Saturn or one of the other planets, then the pull of that planet's gravity might alter the orbit, maybe make it much shorter.
So this comet, if it happens to pass by a planet just the right way, it can be drawn into a new orbit, one that will capture it and keep it coming back around the sun much more often. "
L26L4
"Listen to part of a lecture in an art conservation class.So far we have been talking all semester about restoring and preserving pieces of art, like ancient frescoes, early oil paintings, etc.
But although our field is called art conservation, it also involves... what?
Um... preserving other types of cultural materials too.
Very good. Not just art.
Old artifacts are very valuable when they represent early technologies, or contain important historical information.
In fact, let me give you an example.
You've heard about the Greek scholar, Archimedes, who lived more than 2000 years ago, I am sure.
Archimedes was a great mathematician.
For example, he discovered the formula for the volume of a sphere.
Not much of his work has survived, but what has survived is brilliant.
And then in 1906, a palimpsest of Archimedes' writing was discovered.
Now, a palimpsest is a type of manuscript that contains writing that's hidden because something else was written over it later.
I'll explain in a minute.
This Archimedes palimpsest, as it's now called, is by far the most important palimpsest anyone has ever seen.
Because it contains the only known existing copy of Archimedes' treatise, called Method.
Archimedes shows in it how maths can be applied to physics and physical reasoning back to maths problems, which is how he calculated the volume of the sphere, for example.
This maybe commonplace today, but was revolutionary in his time.
A few years ago, the palimpsest was sold at an auction for 2 million dollars.
It could have ended up tucked away in a private collection, but fortunately, the collector who bought it has agreed to have experts restore every single word Archimedes wrote, so the contents can be shared with the world and studied.
But there are two main problems.
What do you think the first one might be?
Jennifer?
Um... well, it sounds like it's extremely old.
So probably some pages are at the point of crumbling into dust?
True. And some are moldy, and some were eaten away at by bookworms.
This thing's really decayed.
But on top of that, there's another issue.
And this is the reason why it's a palimpsest.
You see, the text apparently sat around in a library in Constantinople until 1229 A.D..But then a scribe erased, scraped away the writing
as clean as he could in order to use the pages to write his own book on.
Why would he do that? Take a guess.
Must have been a paper shortage?
Well, they used parchment to write on, but yes, there was a parchment shortage.
So you are saying the parchment was basically recycled?
Correct. Then, even later on, in the twentieth century, a forger painted ancient-looking pictures on several of the pages in order to make the book seem older and increase its value.
So unfortunately, that's quite a history.
But professor Wilkens, if the scribe scraped away Archimedes' words and if these paintings covered the pages, how can the original work be recovered?
Ah, that's why I am telling you the story.
That's our task as conservationists, isn't it?
To find a way.
There were still faint traces of Archimedes' words on the pages.
First, we tried to make the Archimedes' words stand out with a variety of technologies, using ultraviolet light.
But that didn't work on every page.
But then, there was this new idea that came from a scientist studying spinach.
Spinach?
Yes, spinach. This physicist, Uwe Bergman, does research that involves studying iron in spinach.
He was reading an article about problems with palimpsest and it said that there is iron in the original Archimedes' ink.So he came up with an idea to use the same method of looking at iron in spinach to view
the iron on the palimpsest pages.
And his idea worked.
Bergman's technique allow X-rays to pass through the forged paintings, pass through the scribe's writing to hit the iron traces from the ink of the original Archimedes' text and create an image just of the iron on the pages.
The iron-based letters seem to just pop off the page.
The original text and diagrams emerged, line by line, diagram after diagram.
And that's kind of typical of our field.
There's a lot of interdisciplinary work.
People from several different fields might be involved in working with a single art. "
L27C1
"listen to part of a conversation at the information desk in the libraryHi. Can I help you ?
Where do I go, besides the computers, to look for books on New Zealand?
OK. You mean you don't want to use the computer?
Well, I haven't had any luck on the computers here.
OK. I mean the reason why I am asking is you pretty much have to go to the computer to find out where the book is.
But I can help you find it on the computer if you like.
That would be great, I just spent half an hour and couldn't find anything.
I know how you feel.
When I first started working here, I couldn't find anything either.
So you are looking for information on New Zealand, is that right?
Yes.
Is it like travel information that you are looking for?
Uh... No, actually what I am looking for is information on a volcano in New Zealand.
Oh, OK.
Because I know a travel agency that specializes in tours in New Zealand and Australia.
Oh. I'd love to go. I heard it's beautiful.
Yeah.
Maybe someday.
Yep. OK. Let's see...
OK. If you want search the library holdings and don't know the author's name or exact title of the book or an article, you have to set up a keyword search.
It is a special function.
Then you can just type in some keywords and let the computer do the search.
I see.
OK. Oh, how about we search for volcanos and New Zealand.
Sounds good.
It's for geology class.
Mhmm.
Ha! You must be from Professor Simpson's class.
No.
Oh. Well, he is volcano expert, so I thought he might be teaching your class.
No, I've heard he is really good though.
Yeah. That's what everyone says. Do you know the name of the volcano?
Mount Ruapehu.
Can you spell that?
Sure, it's R-U-A-P-E-H-U.
OK. Mount Ruapehu. Let's see. So are you a geology major?
Hardly.
Let me guess, you have to take a science course and you don't want to have to deal with biology, chemistry or physics.
Exactly. But it's actually turned out to be a pretty interesting class.
Well, that's good. Um... does it have to be a book? Or could you use a journal article?
Uh-huh... no, either one would be fine.
OK, well, here's a journal article. Let me check to see if we have it. OK. We have the article, but it is from 2001. Is that ok, you think?
Well, I'd like to have a look at it.
The focus is really on eruptions in the last five years, but it might have some useful background material.
OK, well, let's see what else we can find.
Sounds good. "
L27L1
"Listen to part of a lecture in a marine biology class.So we have been fairly thorough in our discussion about coral reefs, which of course are prominent, oceanic features made of hard limestone skeletons produced by tiny coral animals.
We've gone over where coral reefs are usually formed - along the edges of shallow ocean banks in tropical or subtropical regions, and the fact that they are declining at an alarming rate.
But I don't want to leave you with the impression that all is lost.
There are several techniques being employed today that could prove useful in assuring the future of the reefs.
Now, we've talked in depth about coral bleaching, or whitening, which as you recall, is a symptom of...well that the coral is suffering.
As you know, coral is very sensitive to water temperature.
Even though one or two degree Celsius rise in sea surface temperature for a relatively short amount of time can cause bleaching.
Recently, researchers have used data collected by monitoring surface water temperatures to improve the ability of a reef to recover from bleaching.
One future possibility is that improved monitoring can help predict where and when bleaching will occur, which might potentially enable us to mitigate its effects.
And there's another technique that's been experimented with to try to help coral reefs recover from bleaching.
It's called coral transplantation.
This involves moving young coral from a healthy reef onto a degraded reef, you know, in an attempt to regenerate the degraded reef by encouraging young healthy coral to take over.
There has been some success with this, but it's still somewhat controversial.
Some scientists support it because, well for one thing, it means you don't have to rely on the existing coral to reestablish itself because it might not be able to.
But in my opinion, transplanting coral should only be used as... well as a last resort.
I mean, this method is not only costly but it's... well even if it's successful, it still fails to address the ongoing problem, the root causes of the degradation, which really is paramount to devising an effective solution.
So I don't really take comfort in the successes they have had with transplantation.
Perhaps some more constructive use of our time could be spent at researching corals that do survive, like in areas known as refugia.
Refugia are areas on the reef that are seemingly, well resistant to bleaching.
See, when coral reefs experience bleaching, it's rarely a case of the whole reef being affected.
There are almost always pockets of coral on the reefs that remain unaffected.
And these are often the lower areas of the reef, those located in deeper water, where temperatures are lower.
Now, we have evidence that corals in these locations are able to escape the destructive bleaching that affects portions of the reef in shallower or warmer water.
So in my mind, it's these refugia that are the key components of overall reef resilience.
These should be the area of concentration for researchers to locate and protect those regions as a way to sustain coral reefs.
And we can also protect the reefs by protecting the surrounding ecosystems, like mangrove forests and seagrass beds.
Both of these grow in coastal waters, often in the vicinity of coral reefs.
By protecting these areas, we also protect the coral.
Let's take, for example, the mangrove forests.
Mangrove root systems have the ability to absorb and well trap sediments and pollutants in water that flows through them before they enter the ocean.
This of course has beneficial results for the nearby coral reefs.
And fishery's management is another key strategy.
Overfishing can be seriously disruptive to coral.
Let me give you a couple of examples.
Overfishing certain species of fish and shellfish like snappers, barracudas and even lobsters.
Well all of these creatures feed on snails, worms and other organisms that eat coral.
So depleting the number of lobsters, for example, means that we are adding to the threat of coral decline.
Sea urchins are another example.
They eat algae and prevent it from overwhelming the coral.
Since the disappearance of sea urchins from the waters up the coast of South Florida, many coral reefs there have been smothered by the uncontrolled growth of algae. "
L27L2
"Listen to part of a lecture in a history of musical instruments class.So musical instruments evolved in ways that optimize their acoustical properties, how the instrument vibrates and sends those vibration through the air to our eardrums.
Now professional musicians are very particular about their instruments, they want instruments that help them fully express the intent of the composer, which of course translates into a more enjoyable listening experience for the audience members.
Yet most audience members probably aren't even aware of how much the instrument matters.
I mean, OK. Think about the last concert you attended.
When you applauded, what went through your mind?
I recently heard a violinist who totally blew me away.
So when I applauded, I guess I was showing my appreciation for his skill, the hours of practicing he must have put in.
And his violin?
Didn't really think about it. It looked exactly like mine, which is inspiring in a way knowing my violin could also produce beautiful tones, that maybe I would sound that good someday.
I hope you do.
But if your violin isn't as good as his...
You mean he might not sound as good playing my violin?
As I said, tone quality differs from instrument to instrument.
The question is why.
Why does one instrument sound more beautiful than another, even if they look identical?
There's a particularly interesting case with an extraordinary generation of violins made in Northern Italy, in the city of Cremona, back in the late 1600s - early 1700s.
These vintage Cremonese violins are considered the best in the world.
But it's not like the makers of those violins were any more skilled than their modern-day counterparts. They weren't.
Today's top violin makers can pretty much replicate all the physical attributes of a Cremonese violin.
But it's generally thought that the acoustical quality of modern violins doesn't live up to the quality of the vintage ones.
So what attributes of the old violins have been replicated?
Oh, their dimensions, shape, their fingerboard height, uh, general craftsmanship.
For a long time, people thought the varnish used to coat and protect the violins was special.
But research showed it was the same ordinary varnish used on furniture.
However, researchers have discovered that there are something special about the wood the violins were made from.
And recently they have been able to replicate that too.
How? Unless the trees that Cremonese used are still alive.
The trees weren't replicated, just the wood, specifically the wood's density.
Density is determined by how trees grow.
Trees, old trees that don't grow in the tropics grow seasonally, they grow faster early in the year in the springtime than they do later in the year.
So early growth wood is relatively porous.
Late growth wood is denser, less porous.
And this variation shows up in the trees growth rings.
The denser layers are generally darker than the less dense layers.
We call this variation the density differential.
Variations in wood density affect vibrations, and therefore, sound.
When scientists first analyzed the wood of vintage Cremonese violins in compared with the modern violin wood, they calculated the average density and found no difference.
Later, other researchers measured the density differential and found a significant difference.
Modern violins had a greater variation, a larger differential.
So you mean the density of the wood in the Cremonese violins is, is more uniform?
Correct. But Northern Italy isn't in the tropics.
No. But climate matters.
Turns out the Cremonese violins were made from trees that grew during a Little Ice Age, a period when temperatures across Europe were significantly lower than normal.
So the trees grew more evenly throughout the year, making the density differential relatively small.
But you said someone replicated the Cremonese wood.
The density differential was replicated.
What did they do?
Try to simulate an Ice Age climate in their greenhouse and grow some trees in there?
No, what happened was a material scientist figured out a way to process wood to make it acoustically similar to the Cremonese wood.
He basically exposed the wood to a species of fungus, uh, a mushroom.
In the forest, fungi are decomposers.
They break down dead wood.
But this particular fungus nibbles away only at certain layers in the wood, leaving other layers alone.
As a result, the density differential of the fungi-treated wood approach that of the Cremonese wood. "
L27C2
"Listen to part of a conversation between a student and the professor of his history of technology class.Would it be okay to focus on something related to agriculture?
Sure, farming technology is fine, as long as it's pre-modern.
But this isn't a long paper, so are you going to need to pick a specific area of pre-modern agriculture, like irrigation or food crops of ancient Greece.
I am actually interested in hydroponics.
Hydroponics.
Growing plants in water instead of soil.
Well, not in pure water, in water that has the proper mix of nutrients.
OK. But is it a pre-modern technology?
I mean, hydroponics isn't really my specialty but from the research I have read, we are talking the nineteenth century, maybe the seventeenth century if you really stretch it.
Oh? But the Aztec civilization back in the thirteenth century in basically where Mexico city is today...
An article I read said the Aztecs were using hydroponics in something they called... I have got the word right here. Um. Chinampas.
Chinampas, the so-called floating gardens.
Exactly. So yeah the chinampas, the article said very clearly these floating gardens are proof that the Aztec invented hydroponic farming.
Well, chinampas are artificial islands built up in shallow lakes.
Islands made from packed earth and weeds and uh, material from the bottom of the lake.
They may have appeared to be floating in the water, but in fact they reach all the way to the bottom of the lake.
So the primary growing medium, what the plants draw nutrients from, is actually soil, not water.
So the article was wrong about that?
Too bad, it seems like a great topic, but I guess...
Wait a minute. Just because chinampas were not technically hydroponic doesn't mean this couldn't be an appropriate topic for your paper.
Chinampas were still a great pre-modern technological achievement.
I mean, they enabled the Aztecs to grow plenty of food in an area without much available farmland.
But I wondered why the author wrote that chinampas were hydroponic.
Well it's pretty common for writers to generalize, say use a term like hydroponics to describe other types of agriculture.
Personally, I would never say hydroponic except for plants growing in liquid.
The crops on chinampas definitely benefited from the water surrounding them. But... hydroponic...
OK. So I will go with chinampas but leave out with the hydroponics part.
Actually, there's an important lesson here.
We should pay attention to what happened in history but also how historical events are presented.
Why, for example, would writers use a word like hydroponics so casually?
I guess 'cause it's a popular topic people want to read about?
Or to help modern-day readers to understand something historical, maybe these writers think a familiar frame of reference is needed.
Well that article was in a popular magazine, not a scholarly journal for historians.
OK. But historians sometimes do the same thing.
So I guess then that all historians might not describe chinampas in quite the same way either.
Good point. Why not look into that too?
And include it along with your description and analysis. "
L27L3
"Listen to part of a lecture in a zoology class.Your reading for today touched on dinosaur fossils from the Mesozoic era, which ended about 65 million years ago.
Today we will be discussing the sauropods.
I think our discussion of sauropods will illustrate what we can learn by comparing the fossil record to modern animals.
By fossils, we mean traces of prehistoric animals such as bones, which become mineralized, or impressions of bones or organs that are left in stone.
Now sauropods were among the largest animals to exist ever!
They were larger than blue whales, which are the largest animals alive today.
They weighed up to one hundred tons, twenty times as much as elephants.
Also, they were an extremely successful kind of dinosaur.
There's evidence of sauropods in the fossil record for an unusually long time, over one hundred million years.
So, why were sauropods so successful?
Biologically speaking, sauropods shouldn't have been successful.
Large animals like elephants, say, they require much more food and energy and have fewer offspring than smaller animals.
This makes maintaining a population harder.
The largest animals today don't live on land.
But in the ocean where food is easier to find: a blue whale, for instance, can eat up to 8,000 pounds of food a day.
And they give birth only once every few years.
We also know that body heat, that... well, large animals can't easily get rid of excess body heat.
But for an oceangoing whale, that's not a problem.
For a 100-ton land animal, it can be.
For years, we have assumed it was the abundant plant life of the Mesozoic that allowed these giants to thrive.
However, we now know that since oxygen levels were much lower in the Mesozoic than we assumed, there was much less plant life for sauropods to eat than we thought.
So now, well, we are looking at other...
We are, we are trying to understand the biology of sauropods, comparing their fossils to the anatomy of modern animals to get a better idea of how they lived.
What we've found is that sauropods were experts at conserving energy.
They had enormous stomach capacity, the ability to digest food over a long period, converting it to energy at a slower pace, saving it for later.
For animals with small stomachs, it takes lots of energy to constantly look for food and then digest it.
With larger stomachs and slower digestion, you don't need as much energy.
Joseph?
Does... do scientists actually know about sauropods from looking at...
I mean, how much can we actually learn looking at some ancient bones compared to all we can learn from modern animals?
And, comparisons between animals that lived millions of years apart? Well, it just seems... more like guessing.
There's always some guesswork when studying extinct animals.
But that's exactly what leads to discoveries, a hypothesis, a type of guess is made.
We test the hypothesis by looking for evidence to support it.
Then some questions are answered, which may lead to new questions.
For example, let's look at one of these comparisons.
We know sauropods couldn't chew food.
Their skulls show they had no chewing muscles.
Lots of modern animals, like birds and reptiles, also can't chew food.
They need to swallow it whole.
But modern animals have an interesting aid for digesting food.
They swallow stones, stones that are used to help grind up the food before it's actually digested in the stomach.
These stones are called gastroliths.
Gastroliths make food easier to digest, essentially smashing food up, just as we do when we chew.
Over time, gastroliths inside the animal are ground down and become smooth and rounded.
Now, sauropod fossils are commonly found with smooth stones.
For years we thought these were gastroliths. They look just like gastroliths and were found in the area of the sauropods' stomachs.
A recent study measured the gastroliths in modern animals, in ostriches.
And the study showed that ostriches need to ingest about one percent of their total body weight in gastroliths.
But we have been able to determine that the stones found with sauropods totaled much less proportionally, less than a tenth of one percent of their body weight.
So now we are not quite sure what these sauropods' stones were used for.
It could be they were accidentally ingested as the sauropods foraged for food, that they served no real purpose.
Other researchers speculate that sauropods ingested these stones as a source of some the minerals they needed, such as calcium.
So the original hypothesis that the stones found with sauropods were gastroliths, even though it hasn't been supported, has helped us to make new hypotheses, which may eventually lead to the answer. "
L27L4
"Listen to part of a lecture in a studio art class.OK. As you probably know, primary colors are, theoretically speaking, the basic colors from which all other colors can be made.
But as you'll find out when you start working on your painting projects, the three primary colors - red, blue, yellow - don't always make the best secondary colors.
Combining red and blue, you will probably never get a fantastic violet.
To get a nice violet, you'll have to add white.
Combining yellow and blue, you will almost never get a satisfactory green.
You are better off using a pure green pigment.
The idea of primary colors, and specifically the idea of red, yellow and blue being THE primary colors, didn't exist until about 200 years ago.
Until then, the dominant theory about color was one that had been proposed by Isaac Newton.
Newton gave a scientific and objective explanation of colors.
He used a prism to break white light down into the various colors of the spectrum.
And he theorized, rightly so, that different colors are essentially different wavelengths of light.
But he made no mention of primary colors.
That idea came from, or was at least published by a man named Johann Wolfgang von Goethe.
Goethe was a well-known author.
He wrote many famous novels, plays, poems.
So why did he start thinking about colors?
Well Goethe was part of the Romantic Movement in western literature.
And he was a Romantic, through and through, meaning that he explained objects and phenomena in terms of the spiritual, emotional impact they had, as opposed to explaining them in terms of their scientific nature.
He rejected an objective understanding of color, in favor of a more subjective understanding.
He believed that when we see color, it stimulates our emotions.
And different colors appeal to or inspire different emotions in different people.
That sounds like psychology.
Well, color theory is used in psychology too.
Some psychologists do use their field's version of color theory to diagnose and treat patients.
Um... anyway, Goethe conducted a number of experiments trying to figure out which colors corresponded to which emotions.
And in terms of that goal, he wasn't very successful.
But his experiments actually did show a lot about the relationships between colors themselves, about how colors change when placed next to other colors, about how they interact with one another.
Scientists studying optics and chromatics today still marvel at his findings.
But Goethe wasn't really able to establish a clear connection between colors and emotions.
Then in 1806, he received a letter from a relatively unknown German artist, a painter named Philipp Otto Runge.
In the letter, Runge outlined his own color theory, specifically the connections he made between colors and emotions.
And his ideas about what colors symbolize, about the emotions that different colors inspire were based on the colors of red, yellow and blue.
Runge's choice of red, yellow and blue had nothing to do with what we know from modern-day chromatics.
It had to do with Runge's complex system of symbolism, his experience of nature, particularly with his experience of the quality of light at various times of the day, morning, noon and night.
So each color had a specific symbolic value.
Well, four years later, Goethe published a book entitled Color Lesson.
In Color Lesson, Goethe COINCIDENTLY cites the same colors as primary colors.
At this point, Goethe was already a well-known author, so he was easily able to popularize this idea of primary colors, and specifically the idea of red, yellow and blue as THE primary colors.
But he didn't mention Runge?
Well, he did put Runge's letter in the book, at the end.
But he added a disclaimer implying that Runge's letter didn't influence his work.
Apparently, what Goethe was saying was that they just happened to come up with the same theory at the same time. "
L28C1
"Listen to part of a conversation between a student and a professor.I am so sorry I am late. Professor Mills.
I just finished at the student medical center.
I twisted my ankle playing soccer this morning.
It took longer than I expected to see the doctor.
That's okay. Don't worry about it. David.
So let's get started.
Your paper on John Dewey's political philosophy has a few issues I'd like to cover.
You gave a great biographical sketch in the beginning.
Okay. But then as you get into his political philosophy, I don't think you've done enough to situate his philosophy within the time period.
In other words, you haven't connected Dewey's philosophy to the thinking of other intellectuals of the time.
So I haven't captured the most critical influences, the influences that were most significant to his political thinking?
Exactly.
OK, now, look back up at the section here, where you wrote about Dewey's view of individuality.
This is all good content, but you haven't presented the information in a systematic way.
I really think this portion on individuality needs to come later, after your paragraphs on Dewey's intellectual influences.
After my revised paragraphs on what influenced them.
Yes. Revised.
Let me ask, uh, when you were finished writing, did you go back and ask yourself if all of the material was relevant?
Well, no.
I do think there are areas that can be cut.
I guess what I am saying is that your paragraphs aren't really presented in a logical order.
The direction of your argument isn't crystal clear.
And there's some unnecessary material getting in the way.
OK. Sounds like I have a lot to do.
And one more thing, do you have a copy of the department's document on the correct format for index, citations and references?
No. I mean, I look at it online when I was working on this assignment.
You really should print it out.
You are going to need it for every paper you write in the political science department.
It looks like you are getting it mix up with another referencing system.
Oh. Yeah, I used something different in high school.
It's so confusing switching to a new system.
I know. But remember, everything needs to be consistent when it comes to referencing.
It's a very important academic convention.
Oh, also, I wanted to ask you... Will you be at the political science club meeting Saturday?
Definitely. The topic is John Dewey.
Yes. Are you interested in leading part of the discussion?
Tom Hayward is looking for someone to help out, I think you'll have a lot to contribute.
That'll be fun. I will give him a call. "
L28L1
"Listen to part of a lecture in a philosophy class.Okay. So, uh, to continue our discussion...
When philosophers talk about the basis of knowledge, they don't mean the source of information about any particular subject.
They mean how we know what we know.
Let's start with one philosophical view - foundationalism.
Foundationalism is the view that our knowledge claims, what we think we know, that is, they need to have a base.
And think of knowledge as a house, you need a solid foundation on which to build your house.
And if you have a strong foundation, your house is more likely to be solid.
Well, foundationalists think the same thing is true of knowledge.
If you have a solid base for your knowledge claims, then your knowledge structure is more likely to be strong valid, true.
First, you need some good foundational knowledge claims, and then the rest of the knowledge claims can be based on these.
Now, as to what kinds of knowledge claims are foundational, well, that's where this gets particularly interesting, in fact it sort of depends on which philosopher you ask.
Take John Locke for instance.
Locke's viewpoint essentially was that when humans are born, their minds are like blank slates, that is, we don't have any kind of knowledge when we are born.
We get our knowledge from our senses, you know, taste, touch, smell, sight, hearing.
So, when we look at the world, first as babies and then as we grow, that's where our knowledge comes from.
Our senses, our experiences serve as the foundation for our knowledge.
Now, for a very different view, let's turn to another philosopher - René Descartes.
Descartes thought that you have to go much deeper to find the foundations.
He believed that our senses are not to be trusted.
So he wanted to find a more solid foundation for knowledge.
He began with what has come to be called methodological doubt.
And when we say methodological doubt, well...
Descartes believed that everything should be questioned, that is, approach it with doubt, and that if you could find one thing that cannot be false, that one thing would serve as a foundation for all other knowledge claims.
So unlike John Locke, Descartes doubts that knowledge comes to him from his senses.
He points out that at some time or another, everyone has been deceived by their senses.
We have all had experiences where our senses have been wrong - illusions, perhaps, mirages.
When driving in a car on a hot summer day, you may see what looks like shimmering water on the road, which, as science tells us, is really just a mirage, an illusion caused by the heating of the air.
Our senses are wrong, they've deceived us.
And Descartes thinks that since our senses can deceive us, we ought not take for granted that what they tell us is really true.
That's the first step in his methodological doubt.
From there he wonders, well, ok, I can doubt my senses, but can I doubt that I am sitting in this room?
Can it seem that we are not really here? That we are somewhere else?
He conceives that most of us would know that we are sitting in the room. But then he says, well, couldn't I just be dreaming?
He's had dreams that were so real that he thought he was awake when in fact he was actually asleep.
And this is another good point.
It's really hard to be sure that you are not actually dreaming.
Yet another proof for Descartes that we can't always trust what our senses are apparently telling us.
We could be dreaming.
And there's really no good way to prove that we are not.
So the common sense picture of reality, that the world is really the way it looks to us, Descartes shows that we cannot just assume this to be true beyond all doubt.
And he does this by talking about illusions and also by arguing that we could be dreaming.
But consider this, he says, while one is thinking or doubting, or doing any of those sorts of mental activities, one has to exist, right?
To even think that I doubt that I exist, you have to exist!
And so what Descartes has done is find at least one thing that he can be certain of.
He says, ""I exist.""
And that's a start. And other knowledge he tells us can be based on that foundation. "
L28L2
"Listen to part of a lecture in an animal behavior class.As you know, researchers have long been interested in discovering exactly how intelligent animals are.
Today we are going to talk about a particular cognitive ability some animals seem to have - the ability to recognize themselves in a mirror.
Oh, I've heard about that. Chimpanzees have it.
Right. Chimpanzees and other primates, chimps, gorillas, orangutans, and of course, humans.
But it's also been found in elephants and bottlenose dolphins, a bit of a surprise.
It's very rare. Most animals don't have it, and it's called mirror self-recognition, or MSR.
Well, how does it work? I mean, how do researchers know if elephants or chimps recognize themselves?
Researchers give them a mirror mark test.
In the mirror mark test, researchers put a mark on the animal where the animal is unable to see it or smell it or feel it, like on the side of their head, without looking in the mirror.
Now, typically, when animals first see themselves in the mirror, they think they are seeing another animal.
Often they will look for this animal behind the mirror.
They may even exhibit aggressive behavior.
But some animals, after this period of exploration, exhibit behaviors that show they know they are looking at themselves.
For instance, elephants will touch the mark on their heads with their trunks.
Now, it's been assumed that primates and some other mammals stood alone at the top of the hierarchy of cognitive evolution.
But recently, birds have been found to possess some of the same cognitive abilities!
In particular, researchers have discovered these abilities in corvids, birds of the corvidae family.
Corvids include ravens, jays, crows and magpies among others.
And what kinds of cognitive abilities are we talking about?
Well, Corvids and some mammals have the ability to plan for the future, to store food for instance, in places where they can find it later.
It's been suggested in fact that jays, corvids known for stealing each other's food, may hide their food precisely because they are projecting their own tendency to steal onto other jays.
So let's talk about a study recently conducted with magpies.
As I said, magpies are corvids.
And because corvids have these other cognitive skills, researchers wanted to see if they were also capable of mirror self-recognition.
So they gave them the mirror mark test, placing yellow sticker on the birds' black throat feathers.
At first, the magpies all engage in the same social behaviors that other animals do-looking behind the mirror, etc.
But eventually, some of the birds, while looking in the mirror, kept scratching at the mark until they got rid of it.
And they didn't scratch at it when there was no mirror around. So they passed the test.
Wow! Do any other birds have this ability?
Well, not that we know of.
There was a study using pigeons, where researchers attempted to reduce MSR to a matter of conditioning, that is, they claimed that the ability to recognize oneself in a mirror could be learned.
So these researchers basically trained some pigeons to pass the mirror mark test.
But two things are noteworthy here.
One, no one's ever replicated the study, but more importantly, it misses the point.
The issue isn't whether some behavior can be learned.
It's whether a species has developed this ability spontaneously.
So what does the test tell us about corvids or chimpanzees?
Good question. For one thing, it is important because it sets animals with a sense of self apart from those without a sense of self.
But more importantly, many researchers believe that MSR is indicative of other advanced cognitive abilities.
Self-awareness, even in its earliest stages, might entail an awareness of others, the ability to see their perspective, to look at the world from another's point of view.
This is crucial, because it implies a high level of cognitive development.
It's perhaps the first stage toward the development of empathy.
But birds' brains are so small compared to primates.
True. Though corvids do have unusually large brains for birds.
But size isn't the whole story.
It's thought that primates are so intelligent because of a certain part of their brains, which birds simply don't have.
But there is an area in birds' brains that researchers believe governs similar cognitive functions.
So primates and birds' brains have evolved along different tracks, but ended up with similar abilities. "
L28C2
"Listen to part of a conversation between a student and a professor.Hi. Sorry, I'm late. Professor Blane.
No problem. Jim
So you've got some questions about your senior thesis requirement?
Yeah. I've got a couple of problems actually.
So, the first thing is, you normally write it during the first half of the academic year. Right?
In your final year of studies.
Right.
But I have my student teaching scheduled for that time.
I want to teach high school English after graduation.
So I really need to give that my full attention. And I just worry that I won't be able to if I am writing my senior thesis at the same time.
I mean, it's supposed to be 35 to 50 pages. That's a serious commitment.
You are right. But it really isn't a problem.
Really?
No. A lot of English majors get teacher certification.
So we have students like you do their senior thesis after their student teaching.
It works out well, because many students want to use a unit they taught as the basis of their paper.
So you'll just enroll in a thesis seminar for the second semester.
Well, that's a big relief. But it brings us to my second problem.
I'd really focus my studies on old and middle English literature.
I am even thinking about doing a graduate degree with a concentration in that after I taught for a while.
So I was hoping to do my senior thesis on Chaucer, on The Canterbury Tales, because that would obviously be useful if I do go on.
But...
Ah. But Professor Johnson...
Exactly. Professor John is going to be taking a sabbatical to do research in France during the second half of the year.
So without him around, I am not sure how I could do a senior thesis on The Canterbury Tales.
I mean, the focus of his teaching and research is unique around here.
Yes, I understand. It would be difficult to do your paper without professor Johnson around.
Hmmm... would you allow me to try to sell you on an alternate plan?
Well, you can try. But Chaucer is sort of my hero, if you know what I mean.
Well, I am teaching a course on the literature of the Renaissance in the first half of the year.
It'll meet late in the day, so it won't interfere with your teaching.
And I haven't offered it in quite a while now, so I doubt you ever studied that period on the college level.
No. I haven't.
If you would be interested in taking the course, I'd be happy to give you supplemental readings, and I'd also be happy to be your advisor for your paper later on.
Well, I never looked at that area before, but I have always had an interest in it. So that does have a certain appeal.
Well, if you do decide to go this route, I would make that decision soon and I would use this summer productively.
After all, this is not going to be like taking an intro course. "
L28L3
"Listen to part of a lecture in a botany class.OK. Last time we talked about photosynthesis, the process by which plants use light to convert carbon dioxide and water into food.
Today I want to talk about another way light affects plants.
I am sure you all know from physics class about how light moves in microscopic ways and that we can only see light when the wavelength of that light is in a specific range.
Plus, depending on the wavelengths, we see different colors.
Well, plants are also capable of distinguishing between different wavelengths of light.
Now, I don't want to confuse you.
It is not like plants have eyes.
Plants don't see in the sense that humans or animals do, but they do have photoreceptors.
Photoreceptors are cells that respond to light by sending out a chemical signal.
And the organism, the plant, reacts to this signal.
In fact, the signals that plants get from their photoreceptors sometimes cause significant reactions.
And many plants are seasonal.
And one way they know when winter is ending and spring is beginning is by sensing the change in light.
The time when an adult plant flowers is based on the amount of light the plant senses.
Certain plant species won't flower if they sense too much light and some plants will only flower if they sense a specific amount of light.
Of course, these aren't conscious reactions.
These plants just automatically respond to light in certain ways.
Plants are also able to distinguish between specific wavelengths of light that the human eye cannot even see!
Specifically there's a wavelength called far-red.
Although why they call it far-red...
I mean, it is not really red at all. It lies in the infrared range of the spectrum.
We can't see it, but plants can sense it as a different wavelength.
OK. Now I need to mention another thing about photosynthesis.
I didn't explain how different wavelengths of light affect photosynthesis.
When a plant absorbs light for performing photosynthesis, it only absorbs some wavelengths of light and reflects others.
Plants absorb most of the red light that hits them, but plants only absorb some of the far-red light that hits them.
They reflect the rest.
Remember this, because it's going to be relevant in an experiment I want to discuss.
This fascinating experiment showed that plants not only detect and react to specific wavelengths of light, plants can also detect and react to changes in the ratio of one wavelength to another.
This experiment was called the Pampas experiment.
The idea behind the Pampas experiment had to do with the response of plants to changes in the ratio of red light to far-red light that the plants sense with their photoreceptors.
Some biologists hypothesize that a plant will stop growing if it's in the shade of another plant, a reaction that's triggered when it senses an unusual ratio of red light to far-red light.
Imagine there are two plants.
One below the other.
The plant on top would absorb most of the red light for photosynthesis, but reflect most of the far-red light.
That would lead to the plant in its shade sensing an unusual ratio.
There will be less red light and more far-red light than normal.
What that ratio signifies is important.
A ratio of less red light to more far-red light would cause a reaction from the plant.
It would stop growing taller, because that plant would sense that it wasn't going to get enough sunlight to provide the energy to grow large.
To test their hypothesis, researchers took some electrical lights, um... actually, they were light-emitting diodes, or LEDs.
These light-emitting diodes could simulate red light.
So they put these LEDs around some plants that were in the shade.
The LEDs produce light that the plants sensed as red.
But, unlike sunlight, the light from these LEDs did not support photosynthesis.
So the plants sensed the proper ratio of red light to far-red light and reacted by continuing to grow taller, while in reality these plants were not getting enough energy from photosynthesis to support all of that growth.
And because they weren't getting enough energy to support their growth, most of the shaded plants died after a short time. "
L28L4
"Listen to part of a lecture in an archaeology class.It's every archaeologist's dream to find a lost civilization, to make some huge discovery, to find artifacts no one else has laid a hand on in millennia.
You might think that this never happens any more, given all the research in archaeology that's been done.
But in the late twentieth century, archaeologists discovered the remains of a sophisticated people whose settlement might have been the hub of a civilization few people even thought existed.
They found this site at the edge of a desert in Turkmenistan, in central Asia, where a series of mounds rise up from the plains.
Now, you might remember because we've talked about this, archaeologists know that mounds such as these are the kinds of geological features that indicate the presence of ancient settlements. Jim?
Um... mounds can be different things, right? Some are burial places...
Exactly. And some are the remains of cities.
The inhabitants would build houses and temples you know, what have you.
And over time, those buildings would fall down or be torn down and then be built over.
Over time, generations of building and rebuilding in the same area would result in a large hill the size of a city.
Careful excavation and documentation of layers in a mound can reveal a wealth of information about the everyday life of people in a settlement over many periods of occupation.
Now, this particular site is called Gonur-depe.
What was found at Gonur-depe was amazing: the ruins of a huge palace complex, the foundations of shops and houses, the remains of thick walls and towers that fortified the city.
There was even an elaborate canal system and a lot of very intricate jewelry.
All these findings seem to indicate that they are the remains of an ancient civilization that was every bit as advanced as other more famous civilizations of the time, like those in Egypt, or, or China.
And the site dates back to 3,000 B.C.E.
Did they trade with those other civilizations?
Because if they did, wouldn't there've been some evidence of that?
You know, an artifact found in the ruins of other civilizations?
That's a good question.
I mentioned Jewelry, well, Jewelry have been found in Mesopotamia and at archaeological sites in modern-day Pakistan.
But archaeologists didn't know where it came from.
Only after the site at Gonur-depe was excavated were archaeologists able to identify it as coming from Gonur-depe.
Uh, Sheryl?
I wonder why nobody found this site before.
Well, before the discovery of this site, it was commonly believed that central Asia had always been occupied by mostly nomadic people.
So there would be no record of major settlements.
A couple of small finds have been made in the area, but really, no one had looked very hard.
Now, one mystery regarding this site is that archaeological records show it was inhabited for only a few centuries.
What happened to the people who lived there?
Well, the site was close to the Murgab river, which they would have depended on for their water.
And the Murgab river, which runs toward the west, is the kind of river that shifts its course over time.
So one theory is that the river's course shifted toward the South, and they simply followed it and built new towns to the South.
Another theory is that they were involved in wars with neighboring settlements.
But we might never know the truth.
One thing we do know is that in the decades since Gonur-depe was discovered, the site has deteriorated significantly.
I mean, it's been disturbed for the first time in millennia.
And being exposed to the Sun and wind has taken its toll on the ancient city.
So now the question is, do we partially restore and rebuild the site before the entire thing disintegrates?
It will take a lot of funding to restore it and I am not sure it'll be made available, which would be a pity.
Even a partly altered site can provide valuable information, which would be lost otherwise. "
L29C1
"Listen to a conversation between a student and an employee at the registrar's office.Morning. How can I help you?
Well, I am kind of confused about my schedule.
I printed it out this morning, but one of the classes I registered for is missing.
OK. Let's see if we can figure this out. What's your name?
Lisa Johnson.
Alright. I'm bringing up your schedule on the computer.
Hmmm... It looks like you registered for Introduction to Astronomy, Survey of American Literature, and Introduction to Government and Politics.
Is that right?
Well, yes, but I also registered for a language class - Level One Japanese.
Did they... I don't know, maybe cancel it?
I doubt it. The Japanese classes are quite popular.
But let's take a look at the list of Japanese classes being offered this semester just to make sure.
Um...what section did you register for?
I don't remember the section number, but it's the one that meets at eleven.
Ah! That would be section five.
Well, according to this, the class is completely full.
Are you sure...you, um, you've registered online, right?
Yeah.
Did you get a confirmation message?
What do you mean?
Well, once you've successfully registered for a class, the computer gives you a message saying you are in.
Oh. You mean that message at the bottom of the screen that says you're now registered for this class?
Actually, I didn't get that message. I got one that said ""instructor's signature required"".
I thought I just needed to get the professor's signature on the first day of class.
Well, you do. But the professor might not sign it.
It depends on how full the class is and how many additional students the professor is willing to let in.
So that means I am not registered for the class.
Not unless the professor signs me in.
What, uh, what should I do now?
Let me give you the form your professor needs to sign.
Go to the class on the first day, get there early, so you can talk to the professor before class starts.
Find out if he or she is willing to let you in.
If so, bring the signed form back here and we'll register you for the class.
If not, well, you'll have to find a different class.
I'd start looking for alternatives now, just in case.
What do you think my chances are getting into this class?
Students often add and drop classes once the semester begins, so there is a real chance a seat would open up.
But of course there are no guarantees.
It's just that I need a language class to graduate and that's the only Japanese class that fits my schedule.
Yes. But according to our records, you are only in your first year here.
If you can't take the class this semester, you still got time.
I know. I was just hoping to take care of my requirements earlier rather than later.
I understand. I just wanted to make sure you knew you had options. "
L29L1
"Listen to part of a lecture in a plant ecology class.So far we have covered biodiversity in the hard wood forest here in the upper peninsula of Michigan from a number of angles.
We've looked at everything from how biodiversity relates to species stability, to competition for forests resources and more.
But now I want to discuss what's called pedodiversity.
Pedodiversity is basically soil diversity.
When we analyze pedodiversity within an area, we are measuring how much variability there is in soil properties and how many different types of soil there are in a particular area.
So we look at soil chemistry.
For example, how much nitrogen or magnesium there's in the soil in one spot.
And we compare it with the chemistry of the soil a short distance away.
Until recently, there hasn't been a whole lot of attention paid to pedodiversity.
But that's changing rapidly.
More and more studies are being done in these fields.
There's a link between biodiversity and pedodiversity, an obvious relationship between soils and flora and fauna, which is why pedodiversity really should be considered in forest management.
A high degree of soil variability in a small area is common, particularly within forests.
If you compare soils from a forest with soils that don't come from a forest, the amount of variability will most likely be greater in the forest's soil.
It generally has more diversity.
Um... OK. There are three main causes of pedodiversity within old-growth forest here in our region of Michigan.
One is tree species.
Different species have different influences on soil formation and soil properties.
For example, pine trees drop pine needles.
And those needles add a lot of acid to the soil.
The organic litter of another tree species might add less acid but more of something else.
A lot of different types of trees in an area might mean more pedodiversity.
Another cause? Gaps... created when trees fall.
You see, where there are gaps, open areas in the forest, the soil there changes.
Um... for instance, without a tree to absorb radiation from the Sun, to offer shade, the full intensity of that radiation reaches the ground.
The soil where the tree used to be heats up.
And without a tree to soak up moisture from the ground, the soil remains wetter than in the surrounding forest.
With a higher temperature and more moist conditions, the process of organic matter decomposition speeds up.
In other words, organic matter gets broken down and added into the soil more quickly in these gaps than in the surrounding forest.
OK. And the third cause: trees being uprooted.
When a tree is uprooted, it might fall into some other trees on its way down, thus falling only partway over.
Or it might crash all the way down to the forest floor.
Either way, if its roots are pulled up from out of the ground as the tree topples over, then there's usually a big hole, a pit left in the ground where the roots used to be.
And there's still a lot of soil attached to the roots, clinging to the roots.
As that soil is eventually shed from the roots by rain and wind and the movement of squirrels climbing around, things like that.
Um... as the soil is shed, it drops down and forms a little hill of dirt, a mound.
Pits and mounds have significantly different soil properties than other areas in the forest.
You get a redistribution and mixing of soil as deep roots are ripped up from the ground.
Rock fragments can be pulled up too, if they've gotten entangled with the roots over the years.
So rock fragments from the subsoil can end up concentrated on the surface.
There are forests management implications I want to point out.
Forests management impacts soil quality.
And when we better understand pedodiversity, we will be better able to predict the impact of forest management on soil.
But in general, for positive impact, forest management practices should mimic natural forest processes.
And the goal should be to promote pedodiversity, and through this, biodiversity in general.
I have a handout, an article on pedodiversity in a section of forests near here.
I want you to read it, because it makes a point that I've only touched on.
From what I have been saying about the causes of pedodiversity, you might assume that the relationship between forest dynamics, what happens to the trees, and pedodiversity is a one-way street.
As the article explains, forest dynamics affects pedodiversity.
But pedodiversity also affects forest dynamics.
It's worth bearing in mind. "
L29L2
"Listen to part of a lecture in an architecture class.Today I'd like to talk a bit about the relationship between the built world and sound.
Uh, the design of buildings like concert halls or theaters.
So, what's the most important aspect in the design of such a building?
Acoustics?
Yes. Now, people have been concerned about how sound carries in auditoriums and theaters for at least 2,000 years.
But it was not until the beginning of the twentieth century that architectural acoustics became a scientific field.
That was when the physicist Wallace Sabine started to do extensive studies on reverberation.
Sabine wanted to find out why the audience could not understand speakers at a lecture hall in Boston.
He designed a series of studies on reverberation to figure it out.
So, what is reverberation?
It's the persistence of sound in a room after the source has stopped making sound.
You see, sound made in a room reflects off the walls, floors and ceiling.
That's the reverberant sound.
The time it takes for the reverberant sound to die down is important for the acoustic quality of a room.
Sabine recognized this and he came up with an equation to measure a room's reverberation time.
So, what happens if the reverberation time is very long?
Wouldn't it be difficult to hear new sounds if you can still hear the old sounds?
Exactly. A long reverberation time may cause musical notes to drown one another out.
On the other hand, if the reverberation time is very short... meaning, the reverberations are absorbed very quickly, the room is called dead.
Performers would feel they have to struggle to fill the room with sound.
We don't want that.
In a concert hall or theater, we prefer a live room, where the sound has fullness.
So we need to control the reverberation time.
After all, we don't want the listeners or the performers have to struggle, right?
So what are some important considerations when we design a theater or a concert hall?
The size of the place?
Absolutely. The larger the room, the longer the reverberation time.
So we'll have to take into account what the room will be mainly used for, since music requires more reverberation than speech.
A room intended for music needs to be designed differently from a room intended for drama.
For music, we need a very large room, a concert hall, actually I should say for full orchestras.
Because for a single instrument, say something like a piano recital, a room with a short reverberation time is better.
So for a solo piano a smaller room works well. Yes?
I read that concert halls designed for symphony orchestras have too much echo for jazz music.
That doesn't surprise me.
Most small jazz groups would need rooms with a shorter reverberation time.
But besides the size of the room, another variable affecting reverberation is the shape of the room.
Let's say you design a rectangular box-like space with bare walls and ceiling, this would allow the sound to act like a ball in a racquetball court, you know, bouncing around and hitting some parts of the walls and ceiling but missing many others.
If that happens in a concert hall, audience members may hear some sounds, but not others.
So what can be done to distribute the sound evenly in every direction?
The answer is: avoid straight, parallel walls. Karen?
But I think I've seen photos of rectangular concert halls.
Right. Older concert halls from the 1800s are generally rectangular.
But they all have a lot of decorations on the walls inside, lots of ornamental plasterwork like statues, which distribute sound very efficiently, reflecting it in all different directions.
And that brings me to another variable we need to consider.
The acoustic characteristics of the building materials as well as the wall and floor coverings.
In fact, most objects you see in a concert hall or theater serve double duty.
The plush chairs absorb sound and soften reverberation.
And the beautiful crystal Chandeliers? They are very good at diffusing sound.
You see, everything must be planned down to the last detail in order to predict the acoustic performance of a room.
That being said, there's something that can't be controlled by the architect.
The audience has an effect on acoustics too.
The heads of people are good diffusers of sound.
And Architects try to account for this effect in their design, but they can't guarantee a full auditorium. "
L29C2
"Listen to a conversation between a student and his music history professor.Um, professor Jenkins.
The listening journal you assigned us to keep for the Intro to World Music class, well, I am not sure I understand what to do.
I listened to the pieces you assigned this week more than once, but when I tried to write about them, I didn't know what to say.
Well, it's not easy to write about music, even for people who are supposedly expert at it.
That makes me feel a little better.
But I am just not familiar with how you keep a listening journal.
I've kept journals for other classes, summarizing and writing about how I felt about readings.
Well, a listening journal isn't all that different, I want you to note your feelings about musical compositions too.
OK. There were pieces I like more than others, but I think you want our comments to be a little more... I don't know, analytical. Right?
Well, whether you like a piece or not is important, but you should be able to explain why you like a particular piece and be able to talk about its historical and musical context.
Actually, the listening journal is a tool to help you listen to music actively, to think about what you are hearing.
Maybe I am finding it difficult because I am not real familiar with most of the music you assigned.
I mean, if it's hip-hop or something I listen to with my friends...
Sure, because hip-hop is a form that's familiar and meaningful to you.
But you'll see as the semester progresses and you start learning more about musical forms, you'll become a more adept listener.
And you'll start noticing patterns.
OK. So the songs we listened to this week, the... the Canto?
The Cante jondol.
You remember we said it means ""deep song"" in Andalusian Spanish?
Not only because it's sung in a deep register, but also because it's a song about deeper or serious matters, certainly not lighthearted.
Really? Hmm... I guess I didn't catch the double meaning.
That's kind of cool.
But anyway, even with the translations you gave us for the lyrics and everything, I don't know, I could tell it's sad, but I guess I wasn't trying to analyze it, from a musical perspective that is.
OK. So this is what you should do. Go back and listen to the song selection and this time pay attention to the melody, to repetition, to the...
There was plenty of that. Some parts sounded like the same note played over and over again.
That's exactly the kind of observation you would record in a listening journal.
So, melody repetition, rhythm, how the piece is structured, as well as your reasons for liking or disliking it.
You know what? I thought everyone was clear about this, but you've just given me a great idea.
I am going to draw up a list of questions everyone should keep in mind when they are writing their journals.
Other students may be having the same problem you are having. "
L29L3
"Listen to part of a lecture in an archaeology class.We will be looking at the original settlement of the Americas next, and I'll spend the next few classes talking about the Clovis people and the two big questions archaeologists have about them.
The two big questions are, when did the Clovis people arrive in the Americas?
And of course, were they the first people in the Western hemisphere.
And we'll get to that. But for today, let's try to get an idea about, well, a question that's not addressed as much as the others and that's - what was their culture like, and how do we figure that out?
Now, again, there's a great debate about when the Clovis people first arrived in the Americas.
And I am not like a lot of archaeologists who want to push the number way back, so let's use a round number and probably a safe number and say 11,000 years ago.
The Clovis people were likely settling North America 11,000 years ago. And leave it at that for now.
Now, most of what we know about the Clovis people comes from one of their tools - the Clovis point.
When we talk about a point we are referring to a piece of stone that's worked to a sharp point, in this case probably to be attached to a spear.
The Clovis point may be the most analyzed artifact in archaeology.
And the point used by Clovis people differs slightly from later points, in the way that the base of the stone is thinned, uh, it's thinner toward the base, the part that's attached to the spear.
So when one is found, it's usually not confused with points made by later groups.
Clovis points have been discovered at both hunting grounds and camp sites, which you might expect.
But another fascinating place we find them is in Clovis caches.
A cache is just something stored or hidden away.
It's also the term for the place where it's hidden.
The Clovis caches are collections of tools, stone points and other tools made of stone or bone, often at various stages of manufacturing, some were left unfinished.
The traditional explanation is that these were emergency supplies, uh, meant to be used at a later time.
Since the Clovis people were highly mobile, it's plausible that they would set up spots along established travel routes where they keep a variety of items, either so that they wouldn't have to carry everything with them or so they could save time once they arrived at a site by not having to make stuff from scratch.
But there's another theory about the caches based on the quality of some of the points we've found.
You see, the points in some caches differ from other points, from points at Clovis camp sites for example.
For one thing, these cache points are quite large, up to twice as large as regular points, so big that you couldn't attach one to a spear say, and expect to throw the spear accurately over any distance.
So what were they for?
Well, it was originally thought that they were unfinished, that someone was working away a point, then had to stop and put it aside in one of these caches to work on later.
The problem is: it's unlikely that a point would have started out as large as the points in these caches, that would be a lot of stone to chip away.
A toolmaker starts with a smaller piece.
And actually, far from being unfinished, a lot of these points really show excellent craftsmanship and attention to detail.
And not just with respect to the skill, but also with respect to the raw material.
It seems that cached points are made from the very best pieces of stone.
So we have to ask: could these points have served another purpose?
Maybe be they weren't just tools.
Look at it this way.
When the Clovis people first arrived in the Americas, they had a lot to learn about their new environment.
Over time, they would have begun to recognize some places as special, important for some reason.
Maybe there was always water available there, or the hunting was especially good.
So maybe the cache was a way to mark the place as significant. "
L29L4
"Listen to part of a lecture in a structural engineering class.Today let's begin to look at structural engineering in the Space Age.
Uh, new problems... new possibilities mean we can think in new ways, find radically different approaches.
So let's consider... uh, well, what would you say is the biggest obstacle today to putting structures, equipment, people... uh, anything really, into space?
Well, the cost, right?
Exactly. I mean, just taking the space shuttle up and back one time is hugely expensive.
Uh, why?
I guess a lot of it is for fuel, right?
To... to get the rocket going fast enough.
OK. Fast enough to...
To escape Earth's gravity.
Good. So we are burning up an enormous amount of fuel at every launch just to get the rocket up to what's known as escape velocity.
Now, escape velocity is around 11 kilometers a second, pretty fast.
But do we really have to go this fast?
Well, yeah. I mean, how else can you, um... escape?
I mean, that's the whole point of escape velocity, right?
Otherwise gravity will pull you back down to the Earth.
Actually, that's a common misconception.
Escape velocity is simply the speed of an object that's... uh, let's say, shot out of a cannon the minimum initial speed, so that the object could later escape Earth's gravity on its own.
But that's just if there's no additional force being applied.
If you keep on supplying force to the object, keep on pushing it upward.
It could pull away from Earth's gravity at any speed.
Even really slow?
So you're saying... like, if you had a ladder tall enough, you could just climb into space?
Yeah! Uh, well, theoretically.
I mean, I can see some practical problems with the ladder example.
Uh, like you might get just a little bit tired out after the first few thousand kilometers or so, uh, especially with all the oxygen tanks you'll have to be hauling up with you.
No. I was thinking more along the lines of an elevator.
Wait! You are serious?
Sure. An elevator. That's a new idea to most of us, but in fact it's been around for over a century.
If we could power such an elevator with solar energy, we could simply rise up into space for a fraction of the cost of a trip by rocket or shuttle.
But wait, elevators don't just rise up.
They have to hang on some kind of wire or track or something.
Uh, true. And for decades that's exactly what's prevented the idea from being feasible or even just taken seriously.
Where do we find the material strong enough yet lightweight enough to act as a cable or track.
I mean, we are talking 36,000 kilometers here.
And the strain on the cable would be more than most materials could bear.
But a new material developed recently has a tensile strength higher than diamond, yet it's much more flexible.
I am talking about carbon nanotubes.
OK. I've read something about carbon nanotubes. They are strong, alright, but aren't they just very short little cylinders in shape?
Ah, yes. But these cylinders cling together at a molecular level.
You pull out one nanotube or a row of nanotubes, and its neighbor's come with it, and their neighbors, and so on.
So you could actually draw out a 36,000-kilometer strand or ribbon of nanotubes stronger than steel, but maybe a thousandth the thickness of a human hair.
OK. Fine. But what's going to hold this ribbon up and keep it rigid enough to support an elevator car?
Well, we definitely have to anchor it at both ends.
So what we need is a really tall tower here on the ground right at the equator and a satellite in geostationary orbit around the Earth.
There's a reason I mentioned that figure of 36,000 kilometers.
That's about how high an object would have to be orbiting straight up from the equator to constantly remain directly above the exact same spot on the rotating planet Earth.
So once you are in this geostationary orbit right over the tower, just lower your carbon nanotube cable down from the satellite, tether it to the tower here on Earth and there you have it!
So you really think this is a possibility? Like, how soon could it happen?
Well, the science fiction writer Arthur C. Clarke talked about building a space elevator back in the 1970s.
And when someone asked him when he thought this idea might become a reality, his reply was, ""Probably about fifty years after everybody quits laughing"". "
L30C1
"Listen to a conversation between a student and an employee at the student activity center.This is the administrative office, right?
Uh-huh. How can I help you?
Well, I am stopping by to reserve a place for my school club that meet and work, pretty much on a regular basis.
Ideally, our preference would be to have our own office.
Hmm, well, we are out of private offices.
But we do have some semi-private options still available.
What do you mean?
Well, it's a setup where you'll have a larger workspace shared by two other clubs.
In other words, each club would have its own work area within that one room.
Oh. Are there any divider, walls or anything?
Oh, yes. There will be a couple of dividers, so there's some privacy.
Um. We'll work with that then, I wouldn't want to be without an office.
OK. Here are the two forms you have to fill out.
Why don' t you do it now while I set that up through our computer system.
OK. So what's your club's name? And the last name of the club president.
Oh, it's the photography club.
And it's Williams. That's me, John Williams.
Hmm, that's not pulling up anything on my screen.
Um, let me try something else, uh, how about your faculty advisor's name?
Sarah Baker. She is in the Arts Department.
Hmm, No. Strange. You know your club is just not showing up in my online records.
Is this an established club?
No. Actually it's a brand-new one.
Hmm, have you completed the registration process?
Yeah, last week. That was my very first step.
Right. Well, for my purposes, a club definitely has to be registered before I can proceed further.
At the moment, however, it appears that there's no record of your club's registration.
Really? I thought everything was finalized last week.
Well, it is surprising.
Usually there's a 24-hour turnaround in our computer database.
So then do you have the registration approval letter from the review committee?
That would give me the verification I need.
Yeah. I do. I mean, well, I don't have it with me.
But, I, I, uh, can get it from my dorm room, bring it back with me and submit it with those forms you need from me.
Great! That'll work.
And just so you are aware, there're lots of benefits to being registered.
Oh, yeah. I think the university will give us permission to set up a website, right?
I want to get students sharing their ideas on the website, you know, establish a photography blog.
Yes. You'll be able to do that.
And, um, actually there's more.
You'll be allowed the use of audiovisual equipment at no cost.
You'll receive a club mailbox and a club email address.
You'll be allowed to post your flyers and posters around the campus for publicity.
And you could be eligible for funding for club events.
Well, we are definitely interested in hiring a professional speaker at one of our campus events at some point in the semester.
And speakers almost always charge a fee. So I'll definitely follow up on that. "
L30L1
"Listen to part of a lecture in a psychology class.We've been talking about animal cognition - the study of animal intelligence.
Now, much of the research in this area is motivated by the search for animal analogues, or parallels to human cognitive processes.
And one of the processes we've been investigating is metacognition.
What is metacognition? Well, it's being aware of what one knows or feels, uh, um... having an awareness of one's state of mind.
And making decisions about behavior based on what one knows.
Researchers have long been interested in whether animals possess this capability, but... but couldn't test it because animals aren't able to report their feelings.
But recently one group of researchers found a way to solve this problem.
They did studies with... with monkeys and dolphins that provide evidence that these animals have the ability to feel uncertainty, to feel unsure about something and... and... well, to know that they are uncertain.
So how could these researchers figure out if an animal feels uncertainty.
Well, it began with a study one of them did on a dolphin, who had been trained to recognize a particular high-pitched tone.
The dolphin was taught to press one of two paddles depending on whether it heard the high tone or one that was lower.
Food was a reward for a correct response.
But if the wrong paddle was pressed, the dolphin had to wait several seconds before it could try again.
The task varied in difficulty according to the pitch of the second tone.
The closer it came in pitch to the first one, the harder it became for the dolphin to correctly identify it as low.
And the researcher noted that the dolphin was quite eager to press the paddle when it was sure of the answer, but exhibited hesitation during difficult trials.
Next the researcher introduced a third option, a third paddle that would initiate a new trial, giving the dolphin the choice of passing on difficult trials.
Once the dolphin figured out the result of pressing this new paddle, it did choose it frequently when the trial was difficult.
The researcher took that as an indication that the animal wanted to pass because it didn't know the answer and knew it didn't know.
But there was a problem.
Other researchers protested that the... the opt-out response was simply a learned or conditioned response.
You remember intro to psychology, right?
In other words, by pressing the pass paddle, the dolphin avoided having to wait and hasten the possibility of a full reward by moving directly to the next trial.
So the experiment didn't necessarily indicate that the dolphin had knowledge of its own uncertainty, just that it wanted to avoid negative consequences.
So more recently, our researcher and his colleagues devised a new study, this time using monkeys.
In this experiment, the monkeys had to identify certain patterns displayed on a computer screen.
These patterns were analogous to the tones used in the dolphin study.
One type of pattern was of a specific density and was to be classified as dense, while the second type of pattern could vary in density, but was always less dense than the first one.
And the monkeys' task was to identify this second type as sparse.
So the denser the second type of pattern was, the more difficult the task became.
And as in a previous study, the monkeys were given a third choice that would allow them to pass on to a new trial.
But unlike in the dolphin experiment, the monkeys had to complete four trials before they got any feedback.
They didn't know if they responded correctly or incorrectly after each trial because there was no reward or punishment.
At the end of four trials, feedback was given.
The monkeys received a full reward for each correct response.
And a time-out during which a buzzer was sounded for each incorrect response.
But the monkeys had no way to tell which reward or punishment was associated with which response.
And they didn't get either reward or punishment for choosing the pass option, the... um... the uncertainty response.
But nevertheless they still chose this option in the appropriate circumstances when the trial was particularly difficult.
And this is evidence that it wasn't simply a conditioned response, because that response didn't guarantee a faster reward.
So what does all this tell us about animal consciousness or animals' awareness of themselves and their state of mind?
Can we really know what's going on in the minds of animals?
No. Of course not.
But exploring the metacognitive capacity of animals could become an important criterion in highlighting the similarities and differences between human and animal minds. "
L30L2
"Listen to part of a lecture in a paleontology class.As we've discussed, birds are apparently descendants of dinosaurs and shared many commonalities with some dinosaur species, like... um... feathers and maybe even flight and of course egg laid.
OK. So, many paleontologists, myself included, have wondered about other similarities between dinosaurs and birds.
Since adult dinosaur fossils have sometimes been discovered near or on top of nests, we've been looking at the dinosaur parenting behavior.
Parenting behavior, well, that sounds so gentle and caring.
But dinosaurs were ferocious reptiles and reptiles don't take care of their young, do they?
Well, some reptiles incubate their eggs, crocodiles do.
And as for popular attitudes towards dinosaurs... well, take the Oviraptor for instance.
In the 1920s, a paleontologist discovered the fossil remains of a small dinosaur near a nest containing eggs.
He assumed the dinosaur was stealing the eggs, so he named it Oviraptor that means egg thief in Latin, which fueled the generally negative public image of such dinosaurs.
But by the 1990s, other experts had convincingly made the case that instead of robbing the nest, the Oviraptor was probably taking care of the eggs.
You see, dinosaurs' closest living relatives - birds and crocodiles - display nesting behavior.
And dinosaur fossils have been found in postures that we now believe to indicate brooding behavior, that is, sitting on the eggs until they hatch.
So we are curious about the type of care dinosaurs gave to their young.
And we'd like to figure out which dinosaur parent, the male or the female gave the care.
Shouldn't the behavior of crocodiles and birds give us some clues then?
Well, with crocodiles, it is the female who guards the nest, and with birds, it depends on the species, it can be the male or the female that takes care the eggs, or both.
In over 90 percent of all bird species, both parents take care of the eggs and the young birds.
But sometimes it's just the male?
Well, exclusive care by the male parent is much less common, but it does occur.
Now, for animals other than birds, the care of young by both parents is pretty unusual in the animal kingdom.
Males contribute to parental care in fewer than five percent of all mammalian species.
It's even less frequent among reptiles, and exclusive care by the male is very rare.
So researchers have wondered about the evolution of male parenting behavior in birds for quite some time.
And now there's research showing that for some of the birds' dinosaur relatives, it's likely that the male parent was also in charge of taking care of the eggs.
How did they figure that out?
Well, first they looked at clutch volume, that's the number of eggs in the nest of crocodiles, birds and three types of dinosaurs, including Oviraptors that are thought to be closely related to the dinosaur ancestors of birds.
So when researchers examined fossilized remains of nests, they found that the dinosaurs had larger clutch volumes, more eggs in the nests that is, than most of the crocodiles and birds that were studied.
But, and this is important, their clutch volumes matched those of birds that have only male parental care.
You see, bird species in which only the males take care of the nest tend to have the largest clutches of eggs.
So what's the connection between bird and dinosaur behavior?
Well, researchers now believe, because of this study, that the male parenting behavior of these birds might have its origins in the behavior of dinosaurs.
Based only on evidence of clutch volume size, the number of eggs?
No, there's more.
They also examined the fossilized bones of those three types of dinosaurs that were found on or near nests to determine their sex.
You see, adult female birds during egg production produce a layer of spongy bone tissue inside certain long bones.
And so did female dinosaurs of the kinds that were investigated.
This spongy tissue serves as a source of calcium for eggshell formation.
But when the dinosaur fossils were examined, there were no spongy bone deposits.
Meaning that those dinosaurs on the nests were probably adult males who wouldn't have needed calcium for making eggshells.
Exactly. And then there's this: birds like the kiwi, the ostrich and the emu, they share certain physical characteristics with these dinosaurs, and interestingly, they also show a consistent pattern of nest care by the male. "
L30C2
"Listen to a conversation between a student and his art history professor.How was the museum?
Great. I hadn't been there for a few years.
Did you enjoy the Van Gogh painting?
That's the thing.
Looks like I have to change my topic.
Hmm... we are getting close to the deadline.
You were writing about the theme of night in the paintings of Vincent Van Gogh.
It's a wonderful topic.
I know, people don't usually think of Van Gogh as an artist of nocturnal themes.
They think of brightness, sunshine, all that yellow and orange.
You are right of course about the intense light associated with his daytime paintings.
But his night paintings don't exactly lack brightness.
That's the paradox that I really like, the paradox of painting a nighttime scene using so much color and light.
So I was planning to focus mostly on his painting Starry Night.
But?
When I went to the museum to look at the actual painting, like you told me to, it wasn't there.
Really? Isn't it part of the permanent collection?
Yes. But it's on loan right now to a museum in Europe.
Ah, I see. Well, I am strict about having students write about paintings they can observe firsthand.
Well, I found another painting I could study instead.
OK.
I read that there are two paintings called Starry Night.
The first one was done by the French realist painter Millet.
It may have been the inspiration for Van Gogh's painting.
Millet's painting is located near my family's house in Connecticut.
And I am going there this weekend and could study it then.
I made sure it's not out on loan.
That definitely would work then.
Van Gogh copied many of Millet's compositions.
We know that he really admired Millet's work.
And a lot of us think Van Gogh saw this particular painting by Millet in Paris in the late 1700s.
Yeah. Although Millet was a realist painter, and Van Gogh a post-impressionist, the two paintings still share lots of features, not just the name.
The most striking shared feature has got to be the amazing light effects.
I am excited to go see it. But one other thing...
Uh-huh.
I was thinking about getting a head start on my next assignment while I am at the gallery in Connecticut, the assignment on miniatures.
They have a lot of miniature portraits of children as part of their permanent collection.
American miniatures?
Yeah. So I figured I could also get started on that essay, study a few while I am there.
I'd focus on the meaning of the objects that some of the children are holding, some are holding flowers, one child has a rattle, another a toy violin...
That would be fine.
Uh, those objects... we call them attributes.
The attributes chosen to be included in a particular miniature was often meant to communicate parents' hopes and dreams for their child.
So I think you'll learn a lot about how people viewed children at the time the miniature paintings were done. "
L30L3
"Listen to part of a lecture in an astronomy class.There's been a lot of talk recently about life on Mars, at the level of microorganisms anyway, mainly because of a few important discoveries and inventions.
For example, one major discovery was that at one point water was present on Mars.
How do we know?
Well, in 2004, an exploration robot discovered jarosite there.
Jarosite is a yellowish brown mineral with a crystalline structure that's also found on Earth.
It contains iron, potassium and hydroxide.
The interesting thing is that on Earth at least it needs highly acidic water to form.
So we've got water or had it at one point.
And since most planetary scientists believe that water is essential to life, the presence of jarosite means that one prerequisite for life was once present on Mars.
But there's another thing about jarosite.
One step in its formation on Earth involves microorganisms.
They actually speed up the formation of jarosite dramatically.
Now, theoretically it is possible for jarosite to form without the help of biological life forms.
But we don't really know for sure if this happens cause... well, because every corner of Earth has some form of biological life.
But jarosite on Earth incorporates all kinds of microorganisms into its crystalline structure.
So it's possible that if the jarosite on Mars was also formed with the help of microorganisms, we might be able to detect remnants of them in the samples we find.
And we have instruments now that will enable us to try to do this.
For example, there's a new instrument called the microfabricated organic analyzer, or M.O.A. .
The organic analyzer is an amazing tool.
It will be able to collect soil samples and analyze them right there on Mars, pure, untouched samples.
It will let us eliminate the risk we would take of contaminating the samples if they were brought back to Earth.
And what they'll look for specifically in the soil is amino acids.
Amino acids, as you may know, are the building blocks of proteins.
In fact, there are twenty standard amino acids involved in making proteins and lots more that aren't.
And here's the important thing: amino acids are what we call handed.
They can exist in two forms, which are mirror images of each other like hands.
Right and left hands have the same number of fingers in the same order plus one thumb.
But right and left hands are not the same. They are mirror images.
Well, like hands, amino acids can be right or left-handed.
And the twenty that make up the proteins on Earth are all left-handed.
Now, one reason the M.O.A. , the organic analyzer is so impressive is that it tests not just for the presence of amino acids but also for the handedness of amino acids.
If amino acids are found, it would be especially interesting if they show a prevalence of one type of handedness, either left, like amino acids on Earth, or right.
See, other physical processes in space, processes that don't involve living organisms,can create amino acids.
But the ones synthesized through abiotic processes, which is to say not involving microorganisms, occur in equal numbers of right- and left-handed.
So, a prevalence of left-handed amino acids would indicate they were biological in origin, which would be amazing!
A prevalence of right-handed ones... well, that would be really amazing!
Because the organisms that created them would be unlike anything we have on Earth, which produce only left-handed ones. "
L30L4
"Listen to part of a lecture in a music history class.The professor has been discussing music of the twentieth century.
And what instrument comes to mind when you think of rock'n roll?
The electric Guitar?
Exactly.
I think it's fair to say that the sound of the electric guitar typifies the rock'n roll genre which became popular in the 1950s.
But really the instrument we know today was the result of a continuing development that started for our practical purposes in the 1920s.
But long before that even people were experimenting with ways to modify traditional acoustic guitars.
The first guitars were wooden.
This is the Spanish guitar and the strings were made from animal products.
Then came steel strings.
And that led to the lap guitar, which is also called the steel guitar because the player slides a steel rod up and down the neck.
And those are all acoustic guitars. OK?
But then eventually we have electric guitars.
Over the years, many inventors and musicians contributed to the design of these instruments.
And each design was intended to alter the sound in some way, at first at least with the electric guitar, to make it louder.
So let's get back to when the steel guitar was first introduced in the United States.
It was right after the Spanish-American war in the late 1890s.
US sailors who were stationed in Hawaii - then a US territory - were very enamored with the music they heard there.
Uh, Hawaiian music was based on the steel guitar I just described.
Some sailors learned how to play the steel guitar and brought it home to the States.
Before long, Hawaiian steel guitar music was all the rage in the mainland US.
It actually had a strong influence on the development of several musical genres, rock'n roll most notably, but also jazz and blues.
Anyway, by the 1920s, with the advent of the public dance movement, people were gathering in large groups to listen to steel guitar music.
But they had trouble hearing it, especially in large public settings.
As I mentioned, the instrument was played horizontally, on the lap.
Since the strings faced upward, the sound was projected toward the ceiling rather than outward toward the audience.
Something had to be done, because the music venues and the audience kept getting larger and larger.
So what would you do?
Find a way to amplify the sound?
Yes. And to do that, inventors started attaching electronic devices, electrical coils to the acoustic guitars.
And the electronics worked!
But attaching electronics didn't just affect how loudly you could play.
It also changed the quality of the sound.
These early electric guitars were hollow and these early amplifiers caused vibrations in the bodies of the instruments.
So as the sound got louder, it became more distorted, fuzzy-sounding.
And what musicians at the time wanted was a pure, clean sound.
So where does Les Paul fit in?
Wasn't he the first to electrify acoustic guitars?
Uh... no. Electrified guitars already existed by the time Les Paul came into the picture around 1940.
What Paul did was experiment with ways of removing the distortions and he succeeded.
He designed a guitar with a solid body that relied solely on electronics.
Paul's solid body eliminated the vibrations, and thus the distortions.
Excuse me. But when I think of electric guitar music, I think of Jimi Hendrix.
Jimi Hendrix, one of my favorites.
But Hendrix's style really was all about distortion, that's what's so great about his music, all those special effects.
I think a lot of rock'n roll fans prefer that to a pure sound.
Yeah. You are getting ahead of me here.
But good, because the point I was going to make is that the sound of rock'n roll changed over the years.
And the designs and technology of electric guitars made those changes possible.
So whereas Les Paul's goal was to remove the distortion, later musicians wanted to produce it.
And by the time Jimi Hendrix came around.
Well, essentially, Hendrix reinvented the electric guitar, in the sense that he created amazing effects and vibrations that changed the sound of rock'n roll completely.
So eventually, people tried to improve on Les Paul's model, well, to modify it I should say. "
L31C1
"Listen to part of a conversation between a student and her United States History professor.So, Amanda, you've asked a lot of questions about trade during the colonial period of the United States.
Has our discussion clarified things for you?
Well, yeah, but now, I think writing about trade for my paper isn't going to work.
Oh, so your questions about shipping routes were for your research paper?
Yeah. But now, I see that I probably need to come up with a new paper topic.
Actually, there was one other idea I had.
I have been thinking about doing something about community planning in the early British settlements in Eastern North America.
Oh. OK.
I am curious.
Why are you interested in doing something on community planning in colonial times?
Well, I am much more into architecture.
It's my major and I mean, planning out a town or city goes along with that.
I mean, not that I don't like history... I am interested in history... really interested...
But I think, you know, for a career, architecture is more for me.
That's great. I've gotten some very thought-provoking papers from students whose interests go beyond history.
Ok. But for the paper you wanted us to try to include a comparison, right?
Yes. Actually, that was really the purpose of the assignment.
The way the United States developed, or perhaps I should say the colonies, since the land that would become the Eastern United States... uh... there were British colonies there four hundred years ago.
But anyway... uh... development in the colonies differed greatly depending on geography.
I'm looking for papers that have ideas about how something that happened one way in the Northern colonies happened a different way in the Southern colonies.
Is that true in terms of urban planning?
Very true. Towns in the Northern colonies were centralized and compact.
They provided a meeting point for exchanging goods, for participatory government, and for practicing religion.
Houses would be built along the roads that led into town.
And just outside the developed area, there would usually be an open field of some sort for grazing animals and also group activities.
Actually, the model for planning a town in the Northern colonies was not unlike the model for the development of towns in medieval Europe.
After all, the colonists had just come from Europe and the medieval period was just ended.
Medieval Europe.
But what about the south?
If I remember correctly... in the South, at least initially, they didn't build towns so much as they built trading posts.
That's right.
Most of the settlers in the North wanted to start a whole new life.
But most of the people who came from Europe to the South just wanted to make some money and then go back.
It is not surprising that some of most common buildings were storage facilities and port facilities. "
L31L1
"Listen to part of a lecture in a music class.Today we are going to do something a little different.
In the past few classes, we've listened to traditional music from around the world and we've talked about the characteristics of these music, what makes these styles distinctive, what kinds of instruments are used.
And you've talked about what sounds familiar to you and what sounds strange.
And many of you found some of what we've listened to very strange indeed.
Well, today I want to start talking about western music and I am going to start in ancient Greece.
But, now here's part that's different.
We're not going to talk very much about the actual music.
Instead, we are going to talk about what the Greeks believed about music.
Now, there are some very good reasons to approach the material in this way.
First, well, we don't have very much ancient Greek music studied.
Only about 45 pieces survived... uh... these are mostly records of poems and songs.
And we are not sure how well we can reproduce the melodies or rhythms, because they were apparently improvised in many cases.
So we really don't know all that much about what the music sounded like.
What we do know about - and this really is the most important reason I am approaching today's lecture the way I am - is the Greek philosophy about music and its continuing influence on western attitudes toward music.
Now, if we're going to understand the philosophy, we have to first understand that music for the Greeks was about much more than entertainment.
Yes, there was music at festivals and we have sculptures and paintings showing people listening to music for many of the same reasons that we do.
But this isn't the whole story.
The important thing about music was that it was governed by rules, mathematical rule.
And for those of you who are also studying music theory, you'll see that it is in fact highly mathematical.
Um.... and for the Greeks, the same mathematical principles that govern music also govern the universe as well as the human character, the essence of personality.
People's characters were believed to be very sensitive to music.
If you started playing around with the rules, you know, messing up the mathematical order, you could do serious harm.
That's why music was considered so powerful.
If you knew the rules it could do great good.
But if you broke them, you could do great harm to the character of the listener.
So, we have this Greek idea that music is directly related to human character and behavior.
The philosopher, Plato, talks about this in the context of education.
For Plato, music is an important element in education, but only the right kind of music.
That means the kind of music that builds the kind of character a good citizen or a future leader would need.
Yes, for Plato, there is a kind of music that instills the qualities of leadership, just as there is a kind of music that makes a person soft and weak.
Now, Plato has very specific, very conventional kinds of music in mind.
He is not fond of innovation.
There were musicians in Plato's day who were experimenting with different melodies and rhythms.
A definite no-no for Plato.
He thinks that breaking with tradition leads to all sorts of social problem, serious problem, even the breakdown of the fabric of society.
I am thinking back now to when I first started listening to rock'n'roll and I remember my father saying it was a bad influence on us.
I think he would have gotten along well with Plato.
Anyway, I don't need to tell you what I think about Plato's ideas about innovation, do I?
Though I have to say it's interesting that the same arguments against new music and art are still being made.
Perhaps like the Greeks, we recognize, and maybe even fear the power of music. "
L31L2
"Listen to part of a lecture in a geology class.As we've discussed, Earth's crust is made up of large plates that rest on a mantle of molten rock.
These plates... uh... known as tectonic plates support the continents and oceans.
Over time, the tectonic plates move and shift, which moves the continents and the ocean floors too.
Once it was understood how these plates move, it was possible to determine past movements of Earth's continents and how these slow movements have reshaped Earth's features at different times.
Ok, Well, studying the movement of the plates can tell us about the location of the continents in the past, it can conceivably tell us about their location in the future too, right?
So, in recent years, some geologists have used plate tectonic theory to make what they call geopredictions.
Geopredictions are guesses about what Earth's surface might look like millions of years from now.
So, we know how certain continents are currently moving.
For example, the continents of Africa has been creeping north toward Europe.
And Australia has been making its way north too, toward Asia.
Does anyone know what's happening to the Americas?
I... I think we've talked about that before. Lisa?
They are moving westward away from Europe and Africa. Right?
Right. And what makes us think that?
The Atlantic Ocean floor is spreading and getting wider, so there is more ocean between the Americas and Europe and Africa.
Ok, And why is it spreading?
Well, the seafloor is split.
There is a ridge, a mountain ridge that runs north and south there.
And new rock material flows up from Earth's interior here, at the split, which forces the two sides of the ocean floor to spread apart, to make room for the new rock material.
Good. And that means, over the short term, uh... and by short term I mean 50 million years, that's a blink of the eye in geological time.
Um... over the short term, we can predict that the Americas will continue to move westward, farther away from Europe, while Africa and Australia will continue to move northward.
But what about over the long term, say 250 million years or more?
Well, over that length of time, forecasts become more uncertain.
But lots of geologists predict that eventually all the continents, including the Antarctica, will merge and become one giant land mass, a super continent, one researchers calling Pangaea Ultima, which more or less means the last super continent.
Now, how that might happen is open to some debate.
Some geologist believe that the Americas will continue to move westward and eventually merge with East Asia.
This hypothesis is based on the direction the Americas are moving in now.
But others hypothesize that a new super continent will form in a different way.
They think that a new subduction zone will might occur at the western edge of the Atlantic Ocean.
Paul, can you remind us what a subduction zone is?
Yeah... Um... basically, a subduction zone is where two tectonic plates collide.
So if an ocean floor tectonic plate meets the edge of a continent and they push against each other, the heavier one sinks down and goes under the other one.
So the...um... the oceanic plate is made of denser and heavier rock, so it begins to sink down under the continental plate and into the mantle.
Right. So the ocean floor would kind of slide under the edge of the continent.
And once the ocean plate begins to sink, it would be affected by another force - slab pull.
Slab pull happens at the subduction zone.
So to continue our example.... as the ocean floor plate begins to sink down into the mantle, it would drag or pull the entire plate along with it.
So more and more of this plate, the ocean floor, would go down under the continent into the mantle. OK?
So, as I said, currently the Atlantic Ocean floor is spreading, getting wider, but some researchers speculate that eventually a subduction zone will occur where the oceanic plate meets the continental plate of the Americas.
If that happens, slab pull could draw the oceanic crust under the continent, actually causing the Americas to move eastward toward Europe and the ocean floor to get smaller.
That is, the Atlantic Ocean would start to close up, narrowing the distance between the eastern edge of the Americas and Europe and Africa.
So they form a single super continent. "
L31C2
"listen to a conversation between a student and an employee at the university center for off-campus study.Hi, I am Tom Arnold.
I am supposed to pick up a packet from the regional center for marine research.
I am doing an internship there this summer.
Yes, I have it right here.
The mail carrier dropped it off a few minutes ago.
Thanks. Um... I wanted to ask about getting credits for the internship.I don't know if...
I might be able to help you with that.
Is there a problem?
I just wanted to make sure the details have been corrected.
The system should show that I am registered to earn four credits.
But as of Friday, nothing was showing up yet.
I was told it would be fixed this morning.
Well, I can check on the computer for you.
Tom Arnold, right?
Yes.
Well, it is showing credits... but only three.
Really? So now what?
These all have to be finalized last week.
Well, yes. The course enrollment period ended last week.
But since our office was supposed to get this straightened out for you before then....
Let me see what I can do.
Uh... did the university give approval for you to earn four credits for this internship?
Because the other students at the center for marine research are only getting three.
Um... I am pretty sure those other students are doing the internship at the center's aquarium, taking classes in marine biology and then teaching visitors about the various displays.
I am doing a special research internship with the center.
We'll be collecting data on changes to the seafloor out in the open ocean.
Oh, that sounds quite advanced.
Well, the internship requires me to have scuba diving certification and to be a senior oceanography student.
I want to do advanced study in oceanography when I graduate.
So I really want to get a sense of what real research is like.
I see.
Now let's try and see if we can...
Oh, ok. I see the problem.
There are two kinds of internships listed here - regular and research.
Yours is listed as regular so it is only showing three credits.
Can you switch it?
Not yet.
But it lists Professor Leonard as...
She is in charge of all the internships.
She just needs to send an email so I have an official record.
Then I can switch it.And that should solve everything.
Great! And I know Professor Leonard is in her office this afternoon, so I can go there later.
It will be such a relief to get all these paperwork completed. "
L31L3
"Listen to part of a lecture in a Marine Biology class.We've been talking about the decline of coral reefs in tropical areas all over the world... um... how natural and man-made stresses are causing them to degrade, and in some cases, to die.
So now let's focus on a specific example of a natural predator that can cause a lot of damage to coral reefs - The Crown of Thorns, or Cot starfish.
The Cot starfish is found on coral reefs in the tropical Pacific Ocean and it eats coral.
Now, in small numbers, the starfish don't affect coral reefs dramatically.
But periodically the starfish population explodes.
And when that happens, the reefs can become badly damaged or even destroyed, something we are trying very hard to prevent.
For example, during the 1960, there was an outbreak of Cot starfish in the Great Barrier Reef, off the east coast of Australia.
Luckily, the Cot starfish population gradually declined on its own and the reefs recovered.
But we were left wondering - what cause the population to increase so suddenly?
Well, over the years, we've come up with a few hypotheses, all still hotly debated.
One hypothesis is that it's a natural phenomenon, that the starfish naturally undergo population fluctuations following particularly good spawning years.
There are also several hypotheses that suggest some sort of human activities are partly responsible, like fishing.
There are fish and snails that eat starfish, particularly the giant triton snail, which is main predator of the starfish.
These fish and snails have themselves experienced a decline in population because of overfishing by humans.
So with a decline in starfish predators, the starfish population can increase.
Another hypothesized human-related cause is fertilizer runoff.
People use fertilizer for their crops and plants and a lot of it eventually makes its way from land into the seas.
It's fertilizer, so it has a lot of nutrients.
These nutrients have an effect on the starfish, because they cause an increase in the growth of phytoplankton.
Phytoplankton are microscopic plants that grow in the ocean.
Larval Cot starfish eat phytoplankton in their first month of life, so more fertilizer in the ocean means more phytoplankton, which means more starfish, bad for the reefs.
Now, the final hypothesis has to do with the storm events.
If some reefs are destroyed by storms starfish populations that inhabited those reefs would have to condense and concentrate on the reefs that are left.
So this can cause a kind of mass feeding frenzy.
So we have ideas, but no real answer.
And because we aren't sure of the causes for starfish population increases, it's difficult to prevent them.
I mean, some progress has been made.
For example, new survey techniques have enabled us to detect population increases when the starfish are quite young, so we can be ready for them.
But meaningful progress requires much better evidence about the cause.
On the bright side, in all the research being done on causes, we have discovered something related to how starfish populations might affect coral reef diversity.
We think that when reefs are damaged, after a few years, the fastest-growing corals repopulate the areas.
And these fast-growing species can grow over the slower-growing species of coral, denying them light and preventing them from recovery.
However, the faster-growing coral species are the preferred food of Cot starfish.
So when an outbreak of Cot starfish occurs, they thin out the fast growing coral and may give the slower ones a chance to reestablish.
So without the outbreak, the diversity of coral would be reduced. "
L31L4
"Listen to part of a lecture in an anthropology class.So now that we've discussed how people in ancient societies tamed animals like cows and chickens for food and other uses.
I'd like to talk about an ancient culture that domesticated horses.
It's the Botai people.
The Botai culture thrived over 5000years ago in central Asia, in what is now northern Kazakhstan.
Pretty much all of what we know about the Botai comes from three archaeological sites.
And we learned the Botai were able to build large perennial villages, sometimes with hundreds of homes.
We also found horse bones at these sites and these can be traced back to the time of the Botai settlements.
The climate that the Botai culture lived in... it was harsh.
And the Botai people... they didn't really seem to have much in the way of agriculture going on.
So their whole economy was really based on horses .
And because horses can withstand the tough climate, they can survive ice storms and they don't need heated barns.
The Botai people could settle in one place and rely on horses for food, clothing and transportation.
So the Botai were the first to domesticate horses?
Well, we are pretty sure that horses were first domesticated a bit earlier, to the northwest, in the area that is now Ukraine and western Russian.
It's quite possible that some of those people later migrated east to Kazakhstan.
But what exactly tells us that these Botai people, that the horses in their area were really domesticated?
As with most ancient history, there is not much that we can be certain about.
But we know there was a significant population of wild horses in that area.
So there were plenty of opportunities for the Botai people to find horses to domesticate.
We also know that horse milk was an important source of food for the Botai people.
What? Milking a wild horse? Well, now, that would be impossible... to milk a wild horse.
And then... there's the...
Oh, Yes? Eric.
So you said last week that for some animals, like for dogs, there were physical changes taking place over the course of generations of dogs because of domestication.
So can we tell from those horse bones if it was sort the same for horses?
Actually, it wasn't.
We know that horses have not changed a lot physically as a result of domestication.
So those ancient horse bones don't tell us much about domestication.
But... we've found that... um... we've found what maybe pens or corrals in the Botai settlements.
And not too long ago, a new approach was used to find out if the Botai people were keeping horses.
Soil samples from these pens or corrals show ten times the concentration of phosphorus.
Um... phosphorus?
Yes. Phosphorus is a very significant indicator that horses, large numbers of horses were being kept in those settlements.
You see, horse manure, horse waste is rich in phosphorus and also nitrogen compared to normal soil.
But nitrogen is an unstable element.
It can be washed out when it rains or it can be released to the atmosphere, whereas phosphorus combines with calcium and iron, and can be preserved in the soil for thousands of years.
The soil from the Botai settlement sites was found to have high concentrations of phosphorus and low nitrogen concentrations, which is important since it suggest that what we've got is really old, not something added to the soil more recently.
Wait. So if horses have been there recently, there'd still be lots of nitrogen in the soil.
That's right.
Yes. Karen.
I just read an article.
It said that one way to determine if there was an ancient fireplace at an archaeological site was to check the soil for phosphorus.
So couldn't the phosphorus at the Botai sites just be from the frequent use of fireplaces?
You are absolutely right.
However, when a fireplace leaves behind a lot of phosphorus in the soil, we'd also find an unusually high concentration of potassium.
But the soil at the Botai settlements, it was found with relatively little potassium, which makes it far more likely that the phosphorus came from horses. Ok?
Now, later on, people of the same region, northern Kazakhstan, started raising sheep and cattle.
And that led to a more nomadic culture.
Since sheep and cattle can't survive harsh climates, they needed to be taken south every winter.
Moving around meant working harder but the trade-off was far richer, fattier milk year round and warm clothing from the sheep. "
L32C1
"Listen to a conversation between a student and a bookstore employee.Hi. Can I help you?
Yeah. I need to sell back a textbook.
Are you the person I speak to about that?
I am. But we can't buy textbooks back just yet, because the bookstore's buyback period isn't until next Thursday.
I thought it started this week.
It is only in the last week of the semester after classes are over.
Oh. Well, can you tell me if this book will be on the buyback list.
I can look. But we are still putting the list together.
Professors have to tell us what books they'll definitely need again next semester, and the deadline for them to let us know isn't for a couple of days.
So the list I have here is not really complete.
Um... what class was the book for?
Intro to economics, with Professor Murphy.
Professor Murphy.
OK. I checked earlier and I know she hasn't gotten back to us on that class yet.
So we don't know if she'll use the same book next time.
Usually if an updated edition of a textbook is available, professors will go for that one.
So if this book doesn't end up on the buyback list, what can I do?
I spent over a hundred dollars for it, and I want to get something back.
Well, if a professor didn't assign it for a class here, we could buy back for a wholesaler who would distribute it for sale for another university bookstore.
OK.
Anyway, if professor Murphy does put it on the list, it is important that you come in as early as possible next Thursday.
There's only a limited number of books we would buy back.
Once we get the number of books we need for next semester, we would stop buying them.
OK. So how much money will I get for the book?
Well, if it's on the buyback list, we'll pay fifty percent of what the new price was.
But that also depends on what condition the book is in, so it needs to be cleaned up as much as possible.
Cleaned up?
Because used books show wear and tear, you know, water stains, scruffy covers, yellow highlighting.
You really need to make sure there are no pencil marks on the book.
The price you can get for a text depends on the shape it's in.
You mean I have to erase all the pencil marks?
If you want the best price for it.
And what if you decide the book is too beat-up and don't buy it back.
That does happen.
Well, one more thing you can try is to place an ad in the student newspaper to see if you can sell it directly to another student. "
L32L1
"Listen to part of a lecture in an archaeology class.One of the important aspects of the field of archaeology, one of the things that excites me about the field, is that seemingly insignificant things can suddenly change the way we think about a culture.
We are always making new discoveries that have the potential to challenge widely held beliefs.
Take something like the banana, for example.
It turns out that this ordinary fruit may be forcing scientists to rewrite major parts of African history.
We know the bananas were introduced to Africa via Southeast Asia.
And until recently, we thought we knew when they were introduced - about 2,000 years ago.
But discoveries in Uganda, that's In Eastern Africa, are throwing that into question.
Scientists studying soil samples there discovered evidence of bananas in sediment that was 5000 years old.
Now, let me explain that it's not easy to find traces of ancient bananas.
The fruit is soft and doesn't have any hard seeds that might survive over the ages.
So after 5000 years, you might think there would be nothing left to study.
Well, fortunately for archaeologists, all plants contain what are called phytoliths in their stems and leaves.
Phytoliths are microscopic structures made of silica, and they do not decay.
When plants die and rot away, they leave these phytoliths behind.
Because different plants produce differently shaped phytoliths, scientists can identify the type of plant from ancient remains.
So, those scientists in Uganda, dug down to sediments that were 5000 years old.
And what do you think they found?
Banana phytoliths.
Obviously this meant that we had to rethink our previous notions about when bananas first arrived in Africa.
But, well, this discovery had other implications for history.
As soon as bananas appear in the archaeological record, we know we have contact between Africa and Southeast Asia.
It would appear now that this contact occurred much earlier than previously thought.
Although... now here's where the uncertainty comes in.
We don't really have any solid evidence of trade between the peoples of these two regions that long ago.
Presumably, if people were bringing bananas to Africa, they'd also be bringing other things too: pottery, tools... all sorts of objects made for trade or daily use.
But any such evidence is missing from the archaeological record.
The early appearance of bananas also suggests that agriculture began in this part of Africa earlier than scientists imagined.
You see, bananas, at least the edible kind, can't grow without human intervention.
They have to be cultivated.
People need to plant them and care for them.
So if bananas were present in Uganda 5000 years ago, we would have to assume... that... that... that someone planted them.
But, there are questions about this too.
We know that bananas can be a staple food that can support large populations, as they did in Uganda in the more recent past.
If bananas were grown thousands of years ago, why don't we see evidence of large populations thriving in the area earlier?
So we are left with this mystery.
We have what appears to be strong biological evidence that bananas were being cultivated in Uganda as early as 5000 years ago.
But we are missing other kinds of evidence that would conclusively prove that this is so.
Clearly, more research needs to be done.
Perhaps by some young scholars from this university?
At least give it some thought. "
L32L2
"Listen to part of a lecture in a biology class.Professor, since we are going to talk about changes in animal populations in the wild, I'd like to ask about something I read in an article online, about how the population size of some animal species can affect other animal species, and how other environmental factors come into play too.
Right. Relationships between animal species in a given ecosystem can get pretty complex.
Because in addition to predator-prey relationships, there are other variables that affect population size.
The article mentioned that populations of predators and their prey might go up rapidly and then decline all of a sudden.
Oh. Yeah! I read about that in my ecology class.
It happens in cycles, I think that's called a boom-and-bust cycle. Right?
OK. Well, hold on a second.
First I want to go over some key concepts.
Let's say there was a species that had access to plenty of food and ideal conditions.
Under those circumstances, its population would increase exponentially, meaning it would increase at an ever-accelerating pace.
Wow! That sounds a little scary.
Well, it doesn't usually happen.
Like you said, a rapid population growth is often followed by a sudden decline.
But we do occasionally see exponential growth in nonnative species when they are transplanted into a new environment.
Because they face little competition and have favorable growing conditions.
But for most species, most of the time, resources are finite.
There's only so much available... which leads me to my point.
Every ecosystem has what's called a carrying capacity.
The carrying capacity is the maximum population size of a species that can be sustained by the resources of a particular ecosystem.
Resources are, of course, food, water, and just as important, space.
Although every species has a maximum rate at which the population of that species could increase, assuming ideal conditions for the species in its environment, there are always going to be environmental factors that limit population growth.
This is called environmental resistance.
Environmental resistance is important because it stops populations from growing out of control.
Factors such as food supply, predation and disease affect population size, and can change from year to year or season to season.
OK. I think I get it.
Well, let's look at a case study.
That should make things clear.
Some years ago, some of my colleagues conducted an experiment in an oak forest involving three different species: white-footed mice, gypsy moths and oak trees.
OK. Now let me explain what the situation is in this forest.
Oak trees produce acorns, and acorns are a primary food source for white-footed mice.
Another food source for the white-footed mice is the gypsy moth.
So the size of the gypsy moth population is controlled by the white-footed mice, which is a good thing because gypsy moth caterpillars are considered pests.
They strip away the leaves from the oak trees every ten years or so.
So the mice eat both acorns from the oak trees and gypsy moths...
And the gypsy moth caterpillars eat oak tree leaves.
Right. Now, what makes this set of relationships particularly interesting is that oak trees only produce a large number of acorns once every few years.
So during the years with fewer acorns, the white-footed mice have to deal with a smaller food supply.
Yes. But in the years with large amounts of acorns, the mice have more food, which leads to...
The white-footed mice population growing.
And the gypsy moth population decreasing.
How can we know that for sure? It seems like a big jump from more acorns to fewer gypsy moths.
Well, we can know for sure because in this oak forest, the researchers decided to test the links between acorns and the two animal species.
In some parts of the forest, they had volunteers drop a large number of extra acorns on the forest floor.
And in another section of the forest, they removed a number of white-footed mice.
In the forest areas where extra acorns had been dropped, the gypsy moth population soon went into a significant decline.
But in the section of the forest where the white-footed mice had been removed, the gypsy moth population exploded. "
L32C2
"listen to a conversation between a student and an anthropology professor.So how was the field trip to the Nature Center yesterday?
You are in that biology class, aren't you?
Yeah. I am. The trip was amazing.
We took a hike through the woods and our guide pointed out all kinds of animal and plant species.
She could identify every bird, every tree, I have to tell you.
I was very impressed with her knowledge.
I am glad to hear you enjoyed the trip.
Well, I am interested in getting an advanced degree in forestry after I graduate from here.
So I love all this stuff.
And actually, yesterday's trip got me thinking about my research paper for your class.
Wonderful! Tell me more.
So our guide was talking about how the human need for natural resources had shaped the environment.
And I just assumed that the human impact on the environment was always destructive.
Um, but that's not necessarily true.
Yeah. That's what she was telling us.
She said there's archaeological evidence that some prehistoric cultures relied heavily on dead wood for fuel, or just cut off some of the branches of trees instead of killing the whole tree.
It is so funny you mentioned that.
I was just reading an article about an archaeological site in Turkey where scientists found evidence that ancient people had been harvesting the branches from pistachio and almond trees.
Of course, when you prune these trees, cutting off just the branches like that, you are actually encouraging more growth.
And you end up with a bigger crop of nuts.
So this was a pretty smart strategy for collecting wood.
See, that's what I'd like to write about.
I want to look at ancient methods of wood harvesting that didn't result in the destruction of the whole forest.
Hums, so you want to write your entire paper on wood harvesting?
Is... is that a problem?
Well, it's certainly a timely topic.
Researchers are investigating this now.
It's just that... well... I am not sure how it fits with the assignment.
Remember you are supposed to be focusing on a particular culture or region.
Yeah. Actually I was planning on writing about the wood harvesting practices of the people who lived here.
You know, the Native Americans who were living in this area and what that might tell us about how they lived.
OK. Well, that's a possibility.
I just want to make sure you can find enough information on that topic to write a well-developed paper.
I'd like you to get started on your research right away.
Maybe even talk to that nature guide and show me what information you can find.
Then we can talk about whether or not your topic will work. "
L32L3
"Listen to part of a lecture in an earth science class.The professor is discussing an area of the United States called the Copper Basin.
Now, you may not have heard of the Copper Basin.
It's in the Eastern United States, in the Tennessee River Valley.
It got its name because settlers discovered copper there In 1843.
And soon afterwards, it supported one of the largest metal mining operations in America.
At one time, four mining companies employed 2500 workers in the Copper Basin.
For that time period, it was a huge operation.
Well, this mining operation turned the Copper Basin into a desert.
In the 1840s, when mining operations started, it was a dense green forest.
But in the 1940s, 100 years later, it was as barren as the moon.
Efforts to reclaim the land and restore the basin to the fertile valley it once was ... well, actually, those efforts are still ongoing.
It's been a long and tedious process.
In fact, it was many years before any results were seen.
Copper mining had gone on there for more than 90 years.
The damage couldn't be reversed overnight.
Although I should mention that by 1996, the water in one of the rivers flowing through the basin was clean enough that it was the site of the Olympic whitewater kayaking competition.
And that river is still used now for recreation.
But... anyway... let's analyze the problem.
It wasn't the mining itself that caused such massive destruction.
It was what happened after the copper ore was extracted from the mines.
It was a process called heap roasting.
Copper ore contains sulfur.
And heap roasting was a way to burn away the sulfur in the copper, so they'd be left with something closer to pure copper.
Well, in the process, large vats of raw copper ore are burned slowly, for two or three months actually, to lower the sulfur content.
And this burning, well, let's look at the results.
First, the mines were fairly remote, so there was no way to bring coal or other fuel to keep the fires going.
So they cut down local trees for fuel.
And like I said, the fires burned for months.
That's a lot of fires and a lot of trees.
Deforestation was occurring at a rapid rate.
And it was accelerated by the smoke from the burning ore.
Big clouds of sulfuric smoke, which was toxic to the trees, formed over the areas.
Trees that hadn't been cut for fuel were killed by the fumes.
The sulfur also mixed with the air and created sulfur dioxide
And the sulfur dioxide settled in the clouds fell to the land in droplets of rain and sank into the soil.
This is what we now call acid rain.
You've probably heard of it.
But no one used the term back then.
Anyway... the acid rain created highly acidic soil.
Well, soon the soil became so acidic that nothing could grow, nothing at all.
Vegetation and wild life disappeared.
And it wasn't just the land and the air, it was the water too.
What do you think happen to the rivers?
Well, there are no trees to absorb the rain, and there was a lot of rain.
So the rain eroded the soil and swept it into the rivers.
This is called silting, when soil particles are washed into the rivers.
And the silting continued at an alarming rate.
But this was toxic soil and toxic runoff.
The acid and metals in the soil made the once clear rivers flow bright orange.
So it was really that one step in the process of producing copper.
The problems just built up and up until there was a desert where a beautiful forest used to be.
OK. Now let's look at reforestation and land reclamation efforts. "
L32L4
"Listen to part of a lecture in an architectural history class.So last week we started our unit on residential architecture in the United States.
So today we'll be surveying a number of architects who make contributions to residential architecture in the 19th century.
Now, it's worth noting that people who designed homes at that time probably had to deal with a certain amount of discouragement.
Since there were other architects who thought it was more respectable to design the kind of buildings... and maybe other structures... that were less... less utilitarian in their function.
In fact, an article from an 1876 issue of a journal called The American Architect and Building News stated that, and this is a quote, they stated that ""the planning of house isn't architecture at all.""
So keep that journal article in mind as we look at the work of an architect named Harriet Morrison Irwin.
Harriet Morrison Irwin was from the South, born in North Carolina in 1828.
At the time, there weren't many architects from the southern United States.
And as you might imagine, very few of them were women.
So Irwin was really a pretty exceptional case.
And she wasn't even formally trained as an architect.
Her educational background was in literature.
Yes, Vicky?
So she just had like... unnatural gift for architecture?
Yes. She was actually a writer for several years.
But she did have a penchant for math and engineering, so she read a lot about it on her own.
Um... especially the architectural essays written by the British critic - John Ruskin.
And John Ruskin believed what?
Um... that buildings should have a lot of access to the outdoors to nature.
Ruskin said that being close to nature was great for people's mental and physical health.
Right! So that was an influence.
Now, Harriet Irwin's contribution to architecture was relatively minor but still quite interesting and unique.
She designed a house with a hexagonal shape. Josh?
A house with six sides?
Instead of the standard, you know, four-sided home?
Yeah. The rooms inside the house were also hexagonal six-sided.
So one important thing was that the rooms were arranged around a chimney in the center of the house, which could provide heat for the whole house through flues, uh, small air passageways into each room, as opposed to having a fireplace in every room, which would require more cleaning and make the air inside the house dirtier.
The house's shape also allowed for more windows.
Each room had a large wall that could fit a couple of big windows, giving every room a nice view of the outdoors.
Plus there be good airflow through the house.
Yes. In warm weather when you can open all the windows.
Good. The doors to the house as well... uh... the house didn't have a main entrance or any hallways.
So there could be a couple of entry doors in different places, which like the windows, provided ready access to the outdoors.
So, what other advantages might there be to hexagonal rooms?
OK. Think about cleaning.
What part of a room is usually the hardest to clean?
Like... to sweep with a broom. Right?
Oh! The corners.
Because in square or rectangular rooms, the corners are at 90 degree angles.
It's hard to reach all the dust that gathers in the corners.
But if Irwin's rooms were closer to a circle than a square.
It would be easier to reach all the dust and dirt with a broom. Right?
Exactly.
Now... um... biographers who wrote about Irwin in the 19th century, I feel, sort of downplayed the ingenuity of her design.
But I think if she had designed this house today, the same biographer would praise her for coming up with a floor plan that emphasized function, efficient function of a house, as well as a design that's creative and unique.
In any cases, three houses were built in Irwin's time that used her hexagonal design.
And in 1869, when she was 41, Irwin became the first woman in the United States to receive a patent for an architectural design.
And that speaks volumes if you ask me. "
L33C1
"Listen to a conversation between a student and a university employee.Hi. I am a little lost.
Um, is this the housing maintenance office?
You found it. How can I help you?
Oh, good. I have a quick question.
Are we allowed to keep electric heaters in our rooms?
Actually, you are not.
What's going on? Your room cold?
It's freezing in my room.
I think the heat went out or something.
Are you sure it's out?
Maybe it just got turned out too far.
Oh, no. I tried adjusting the, uh, the heat control, but it doesn't make any difference.
It's so cold in my bedroom I can't sleep at night.
I've actually been sleeping on the sofa in the front room.
The heat still works in there.
Actually, we get hot air in all the bedrooms except ours.
Wow! Do you have a roommate?
Yeah. But she said she isn't bothered by the cold.
But on the sofa, I am kept up by the noise out in the hall.
The dorms can sometimes get pretty noisy.
So what can be done about it?
Well, OK. There's a couple of things we can do.
I can have a custodian take a look at it and see if he can do something.
Actually, I asked the custodian yesterday to take a look.
But he said he couldn't find anything wrong.
He said that some of the other rooms have lost heat also and that if we'd come here you guys would fix it.
Oh, he did? That's weird, because I would have... well, the custodians themselves are usually supposed to report any problems right away.
OK. In that case, then what you need to do is... here, fill out this form.
I have to fill out a form?
Yeah, but at least that'll put your heater problem in a work order for the maintenance crew and they'll get to you as soon as possible.
Just so you know, because it's not winter yet and it's not as cold as it could be, it may take a few days for a maintenance crew to get to you.
A few days? I can't even sleep in my own room!
Can't we just get an electric heater?
I am sorry. But students just aren't allowed.
OK. I can see that this is a problem, and not just with your room.
So if you can get the form back to me this afternoon, I'll try to get a maintenance crew to look at your problem by tomorrow.
How's that?
Oh, that would be great.
Seriously. I have to take off now.
But when I fill this form out, I give it to you, right?
Right. And if I am not here, just put it in my box and I'll get it. "
L33L1
"Listen to part of a lecture in an archaeology class.The Great Pyramid of Giza in Egypt might be the most famous building in the world.
We know exactly when it was built.
Construction started in 2547 B.C.E., about 4500 years ago.
We know who had it built.
That was the pharaoh Khufu.
And we know who oversaw its construction - the pharaoh's brother.
We know so many things about it, but the funny thing is: we still don't know exactly how it was built.
This picture will give you an idea of the size of the Pyramid and the size of the blocks it's made out of.
About two million stone blocks were used to build the Great Pyramid and they are incredibly massive.
The average weight is two and a half tons.
The problem that has puzzled scholars for centuries is how were these blocks lifted up the height of this massive structure and then fit into place and without the benefit of modern technology.
Of course, there've been a lot of theories over the centuries.
The oldest recorded one is by the Greek historian Herodotus.
He visited Egypt around 450 B.C.E., when the Pyramid was already 2000 years old.
His theory was that cranes were used, much like we use cranes today to construct tall buildings.
And Herodotus may have seen Egyptians using cranes made of wood.
But the problem with this theory has to do with simple mechanics.
A crane needs a wide and sturdy base to stand on or it will fall over.
Well, as you get toward the top of the Pyramid, there's really no place for a crane to stand.
The stone blocks are too narrow to provide a base.
Well, so much for that theory.
The next one has to do with the use of a ramp that would allow workers to drag a stone block up the side of the structure.
Of course the ramp can't be too steep.
It has to have a long gentle slope.
And that's the problem.
If you build a ramp with a slight slope up to the top of a Pyramid that's over 130 meters high, it would have to be almost two kilometers long.
Well, the Pyramid is built on a flat area called the Giza Plateau.
The Plateau is simply not big enough to accommodate a two-kilometer-long ramp.
OK. So what now?
Well, if you've ever driven on a mountain road, you'd know that it has a lot of twists and turns and bends in it because that's how engineers keep the road from having to be too steep.
So why not wrap the ramp around the Pyramid, building the ramp around it as you go?
Sounds like a pretty good idea.
Except it's got a serious problem.
See... one of the most remarkable things about the Great Pyramid is how accurate the proportions are.
The dimensions are almost perfect.
To get that perfection, the engineers must have had to measure it repeatedly during construction.
And the way you'd measure it is from the four corners of the base.
Well, if you got a ramp spiraling up from the base of the Pyramid, those corners would be buried by that ramp during construction.
Well, who says the ramp has to be on the outside of the Pyramid?
And now we get to the latest idea.
If the ramp were on the inside of the Pyramid, the corners at the base would be exposed so the engineers could do their measurements while they were building.
Well, an architect named Houdin has spent a few years working on making computer models of the building of the Pyramid.
And what Houdin believes is that an exterior straight ramp was used to construct the bottom third of the Pyramid.
This ramp would have been fairly short.
It probably rose less than 50 meters.
Then the rest of the Pyramid was constructed using an internal ramp that spiraled around the inside of the Pyramid.
But how can we test this idea?
Well, there are several ways to look inside the Pyramid.
One is called microgravimetry.
Microgravimetry is a technique that's used to detect voids inside a structure.
You can then take the data and generate an image that shows any empty spaces in the interior.
Well, in 1986, French scientists completed a microgravimetric survey of the Pyramid.
And one of the images they produced showed an empty spiral-shaped space inside it.
The shape of that space corresponds exactly to what Houdin thought the ramp would look like.
I think Herodotus would be convinced.
We might very well be at the end of centuries of guessing. "
L33L2
"Listen to part of a lecture in an environmental science class.I'd like to continue with the topic of managing water resources, but I want to focus on a particular case.
Uh, um, an example of water management that's made us reconsider the methods we use when we make these decisions.
So let's look at what's happening in the Colorado River basin.
The Colorado River basin is a region in the Southwest United States.
Seven states rely on the Colorado's water.
And as you can imagine, as the populations of these states began to grow, it became clear that a system to distribute, uh, to make sure each state got its fair share of water... some kind of system had to be created.
And in 1922, a water-sharing agreement was made.
Elizabeth, you have a question?
Well, how exactly do you figure out how to share a river?
I mean, you can't... like cut it up into pieces.
Well, let's start with the first step.
And that's trying to figure out how much water on average flows through the river each year.
Now, researchers had started gathering data on water flow back in the late 1890s using instruments they placed in the river.
When the 1922 water-sharing agreement was made, there were about twenty years of data on water flow available.
The average annual flow was calculated.
And, well, the agreement was based on that calculation.
The same basic agreement is in effect today.
Wait! That was all the data they had?
And they based their decision on that?
Yes. And we'll see why that was a bad decision in the moment.
OK. As decades passed, it became clear that measuring river flow was much more complicated than we had thought.
See... a river has periods of low flow and periods of high flow.
And this wasn't taken into consideration when the 1922 agreement was made.
In the 1970s, the population of the area was rising while the amount of water flowing through the river seemed to be falling.
By this time, we had... what?
A hundred years of recorded data to look at?
That's still a pretty short time for an ancient river.
To get more data, we looked at a different source - a source that was able to tell us about hundreds of years of the river's history - tree rings.
OK. Let me explain.
You probably know that we can determine a tree's age by counting the rings on a cross section of its trunk.
Each ring represents one year of the tree's life.
So if you know the year the tree was cut, you can count inwards and date each ring all the way back to the center.
You can also tell how much moisture the tree got during each of those years by looking at the width of the rings.
A wide ring means plenty of water while a narrow one indicates less.
Fortunately for us, certain areas of the Colorado River basin are home to some very old trees, some 800 years old and older.
Researchers can drill core samples, uh, basically get a cross section of a tree without having to kill it, look at the rings and get a picture of what the climate was like in the basin for each of the tree's years.
Well, the results tell us something we wouldn't have known without this data, that over the past 500 years or so, the Colorado River basin has experienced severe droughts, some worse than any we've ever recorded.
They also showed that the early to mid-1900s, when most of the data that led to the water-sharing agreement was collected... well, this was the wettest period in the past 400 years.
Well, obviously, had water management officials known then what we know now, the 1922 agreement would have been handled differently.
But today we can use the past to help prepare us for the future.
With the demand for water in the basin states increasing and with the real likelihood of lower flows in the river, if history is our teacher, we can develop innovative methods of water conservation and reevaluate how water is distributed. "
L33C2
"Listen to a conversation between a student and his biology professor.Professor Landrea.
Hi, Dennis. You are right on time. Come on in and have a seat.
Great! Thanks.
So like I told you in class, I just wanted to take a few minutes to meet with everyone to make sure your class presentations for next week are all in order and coming along well.
And as you know, you are supposed to report on some area of recent research in genetics, something... you know... original.
Well, I think I found just the thing!
It actually occurred to me a couple nights ago while I was eating dinner in the cafeteria.
Tell me professor, do you like broccoli?
Broccoli? You mean the vegetable broccoli?
Yeah.
Well, I guess not really.
Me neither. I have never liked it or most other vegetables for that matter... brussels sprouts, asparagus, cauliflower... you name it.
They just taste bitter and... well... nasty to me.
My mother always called me a picky eater.
OK... And?
And so I got to wondering, I mean, I am obviously not the only person like this.
So is this just because of some... like trauma from our childhoods? Some bad experience we've had with some vegetables?
Or could there be some genetic explanation for why some people are picky eaters and others aren't?
OK. I see. Well, I suppose it's a possibility.
Actually, it turns out it's more than a possibility.
I started doing some research in the library that night and I found out that a biologist at the National Institutes of Health has been looking at that very question recently.
Well, I guess that's not too surprising.
And this is great stuff actually.
So what's the verdict?
Well, this guy seems to have discovered a particular gene that actually makes it possible for people to taste the bitterness in certain green vegetables.
But people who have a mutation in that gene cannot taste the bitterness.
Well... that's certainly fascinating!
But... so this biologist is basically claiming that people who like to eat these vegetables actually have some sort of sensory deficit?
Sort of makes us picky eaters than normal ones, doesn't it?
I mean, that's kind of turning things on their head, isn't it?
Well... then again, it wouldn't be the first time, would it?
Think of it this way: humans originally needed to have a stronger sensitivity to bitter-tasting foods so they could learn what plants were good for them and which ones might be poisonous.
But at some point, as people figured out what they could safely eat, this need became less crucial and a segment of the population lost that ability.
OK. Well, you make a compelling case.
I can't wait to hear more about this when you deliver your report. "
L33L3
"Listen to part of a lecture in a biology class.Ways in which animals adapt to their environment are often quite ingenious actually.
And as an example of this, let me tell you about a fish, a group of fish known as the Notothenioids.
There's over 90 known species of Notothenioids and they inhabit both shallow and very deep waters, mostly around Antarctica.
Many are fairly small, though the largest species can weigh up to 150 kilograms.
Notothenioids can be identified by their large eyes, which are covered by a thick insulating layer of clear tissue.
This tissue protects their eyes from freezing.
Remember, the freezing point of ocean water, salt water, is lower than for fresh water, negative 1.9 degree Celsius.
So it can get a lot colder for fish in an ocean, say, than in a river or lake.
So this means that the ocean waters around Antarctica are cold enough to freeze most types of fish, but Notothenioids don't freeze.
In fact, they thrive.
They account for some 95% of all fish in the southern ocean, the ocean that surrounds Antarctica.
So, how unusual is that, to have a single family of fish dominating an entire ocean?
I mean, think of... say, tropical or temperate marine environments, which have incredibly diverse fish populations.
Coral reefs, for example, support over 4000 types of fish, along with sponges, crustaceans, and many other organisms.
So, exactly when and how did the Notothenioids come to dominate the southern ocean?
Well, around 30 million years ago, the waters around Antarctica were a lot warmer than they are today.
Um... at that time, Antarctica was connected to South America, which means that warm air from the north could flow southward and heat up the Antarctica waters.
Because the water around Antarctica then was relatively warm, it supported many types of fish.
And we know this from fossil evidence.
But the 90 or so species of Notothenioids that exist today didn't exist at all back then.
In fact, only one ancestral Notothenioid species existed.
But somewhere between 5 million and 14 million years ago, two major changes took place.
First, what we call a chance mutation.
A tiny genetic change occurred in that one Notothenioid species.
Its DNA allowed for the production of a special protein, a protein that prevents the fish from freezing.
The way this... this anti-freeze protein works is: it binds to any ice crystals that form inside the fish.
This binding action prevents the ice crystals from growing larger.
And this is what prevents Notothenioids from freezing.
Now, at that time, the waters the Notothenioids inhabited were still not freezing cold, so the protein didn't really make a difference as far as the fish's survival.
But this would change, because in the same period of geologic time there was a shift in the earth's continental plates.
Continental drift caused Antarctica to move apart from the landmass of South America and to drift into the Southern Polar Region.
This resulted in a powerful water current encircling Antarctica, which prevented the Antarctic waters from mixing with warmer water.
So the southern ocean, isolated from that warm airflow from the north, cooled down drastically, to the kinds of sub-freezing temperatures we associate with it today.
Now, most fish species couldn't survive in this frigid environment and they became extinct.
But that one Notothenioid species, with its unique ability to produce that anti-freeze protein, thrived.
It had virtually the entire southern ocean to itself!
So? Well, there was little or no competition for food or space.
You might think of it as... um... as a... a kind of ecological vacuum.
And the Notothenioids exploited fully.
The species migrated into different habitats throughout the southern ocean.
And its population increased dramatically, with various sub-populations migrating into different parts of the ocean.
Over time these sub-populations in all those different habitats... well, they developed very different physical traits.
They adapted to survive in their particular ecological niche, their... their position within a particular ecosystem.
We call this type of species diversification within a species ""adaptive radiation"".
And what adaptive radiation is, is an evolutionary process by which a parent species rapidly undergoes changes resulting in various new species in order to fill multiple ecological niches.
So in the case of the Notothenioids, that single species started colonizing empty habitats to such an extent that it evolved into a broad range of new species, the 90 or so Notothenioid species that we have today.
So let me switch to adaptive radiation with regard to another species that's also been very successful. "
L33L4
"Listen to part of a lecture in an art history class.OK. We have been talking about the art and architecture of the Italian Renaissance, from around A.D. 1400 to around A.D. 1600.
Last class, we had a look at some of the magnificent palaces and villas built during this time period.
And just as class was ending, someone asked about the gardens associated with these palaces and villas.
And so I'd like to say a few things about them before we move on.
Now, when I say gardens, I don't mean vegetable gardens or simple flower gardens.
These were lavishly constructed, finely detailed gardens that covered hundreds of acres, with exotic plants and ornamental statues.
And they were just as much a symbol of their owners' social position as their palaces and villas were.
Again, what was the inspiration for the Renaissance? Rebecca.
Classical art and architecture of the ancient Greeks and Romans.
That's right.
As we've said before, the main point of the Renaissance was to revive the genius of the ancient Greeks and Romans, which is why designers of Renaissance gardens designed them as the ancient Romans would have designed them, or at least as they imagined the ancient Romans would have designed them.
How did they know what ancient Roman gardens look like?
Well, they didn't have any pictures.
But they did have some very detailed descriptions of ancient Roman villas and their gardens that had been written by famous Roman authors who lived during the height of the Roman Empire.
And at least three of those authors, one was a scholar, one was a poet, and one was lawyer, were very authoritative, very reliable sources.
Ah... and interestingly enough, there was another source that didn't describe classical gardens but still became a great influence on Renaissance gardens.
It was also written back during the height of the Roman Empire by a mathematician known as Hero of Alexandria.
Hero was a Greek.
But he lived in Alexandria, Egypt, which was at the time part of the Roman Empire.
Hero compiled descriptions and sketches of seventy some clever little mechanical devices, most of which utilized compressed air to cause water, or in some cases wine, to flow from one place to another, or sometimes to squirt or to make some kind of noise.
Yes? John?
Could you give an example?
Well, one of the devices was a sacrificial vessel that was obviously designed for a temple, not for a garden.
Anyway, if you drop money into this vessel, water would flow out of it.
Well, creative minds in the Renaissance realized that this little device could be nicely repurposed as a nifty little fountain.
Designers of Renaissance gardens loved this sort of thing.
They loved to incorporate novelties and tricks, things to amuse and impress guests.
And that was the purpose? To impress people?
Sure. As a nobleman or wealthy landowner, one purpose of having a fabulous villa with a fantastic garden was to impress people.
It was a way of proving your social position.
Well... OK. You also mentioned tricks.
Well, for example, some gardens had plaster or marble birds that sang when water flowed through them.
Some fountains were designed to squirt people with water.
And these things were popular?
Yes. They may have been the most popular features of the gardens.
I mean, flowers and statues can be nice to look at, but these things were a lot more fun.
And the more clever the device is, the more famous the garden and the greater prestige the landowner enjoyed.
Yes? Rebecca.
What about mazes?
I read that they were a major part of the Renaissance gardens.
Oh, yes. They certainly were!
Mazes or labyrinths, as they're also called, were very common in Renaissance gardens.
How that came to be though is a bit of a mystery.
Mazes have a long history going back to the ancient Egyptians, but they started appearing in gardens only during the Renaissance, or perhaps just a little bit prior to that.
According to one source, what happened was: in the late 1400s, a highly respected expert published a book on architecture.
And readers somehow mistakenly inferred from that book that ancient Romans had mazes in their gardens.
So then designers of Renaissance gardens thinking they were following in the footsteps of the ancient Romans... well... guess what they did. "
L34C1
"Listen to a conversation between a student and an employee in the university library.Ready to check out?
Just about, before I do though, this book on early navigation,
I've been using this book quite a bit for a research project and I'd like to own it actually, and, well, it's an old book and there were two copies on the shelf just now, so I was wondering if I could buy one?
I was talking to this guy the other day and he said the library sold books on occasion.
Is that right?
He's probably talking about our annual book sale.
We have one every spring.
OK, how do you decide which book to sell? Are they duplicates?
A lot are duplicates.
If we have more than one copy of a title and it hasn't been checked out in a few years, in that case, it might end up in the sale.
I've actually tried to find this book on-line but no luck so far.
I was really hoping to buy it.
Well, that particular book, well, it probably won't be up for sale this year.
Most of the books in the sale come from off-site storage.
Off-site storage?
That's where we keep books that haven't been used for several years.
They're still in the catalog which means they can be checked out if you fill out a form.
It takes maybe a day or two to retrieve one of them.
I see.
And then before we decide to include a book in the sale, we review its circulation history again which can take a while.
We've got a lot of books in storage.
So it's basically the unpopular books that get put up for sale then.
Well, that, plus the main thing is to make sure students have access to the information in the books.
A lot of them are available in electronic format these days, even the really old ones.
You know they've been preserved that way.
So most of the books for sale are older books.
Well, we get book donations too and lots of those are new.
Again, a librarian reviews them and decides whether to catalog them or put them up for sale.
Is the sale open to the public?
On the second day, it's a two-day sale.
The first day is for students, faculty and staff though which is great.
We usually need about 20 volunteers for the sale and, well, if you volunteer, you get first shot at everything in advance.
Really? What do volunteers have to do?
You help sort the books and set up the tables.
But keep in mind, those positions fill up quickly.
Now, about this particular book, it wouldn't hurt to send a formal request to the collection department.
They might be able to let you know if it'd be up for sale.
I'll do that. Thanks. "
L34L1
"Listen to part of a lecture in an Art History class.All right, so last week we started talking about the painters and sculptors who were part of the art movement called Dada.
But I don't want you to think the ideas we introduced last time were limited to painting, sculpture, that sort of thing.
So, today I want to move beyond the visual arts and talk a bit about Dada in the performing arts, in theater.
But let's start by reviewing what Dada is, OK?
As you recall, Dada began in Switzerland in the city of Zurich in 1916.
The artists who started it were reacting against traditional notions of, uh, uh, of beauty, of reason, of progress which had been the standards of western thoughts since the eighteenth century.
They looked around and, well, I mean, the First World War was raging.
So they didn't see much beauty, reason or progress in the world.
Instead, they saw a world that was chaotic, random, a world that didn't make sense.
And if that's the way the world was, they wanted their art to reflect that.
So, let's review a couple of key ideas that were the backbone of Dada art.
First, the Dadaist wanted to completely reject the classical idea of art, classical ideas like proportion, balance, all the things you think about when you think about great art.
Great art involved a reason, the logic, the beauty that the Dadaist wanted to overthrow.
So, uh, well, you know, to a Dadaist, classical art work was a reflection of outdated thinking.
That's why Dadaist created sculptures like the ones we saw last week.
Remember the stool with the bicycle-wheel mounted on top?
I wouldn't exactly call that beautiful, would you?
But, of course, it wasn't meant to be.
That was the point.
OK, so another key Dada idea we talked about was the embracing of randomness, right?
Uh, if life was random, said the Dadaist, why would we make art that has order and logic?
And so we have that collage we looked at with an artist took different, you know, cut out squares of colored paper.
Threw them onto the canvas and wherever they landed, that was the composition of the work.
Another favorite of the Dadaist was something called chance poetry.
A chance poet would pull words out of a hat.
And that would be, well, that would make up the, the poem.
And this idea of chance and randomness was a key element of Dadaism because the whole world seems so random to them.
So, now, let's take a look at how Dadaist ideas were presented to audiences in highly unconventional, well, I'm not even sure how to categorize these theatrical events.
I suppose you just have to call them shows.
These shows started in Zurich in a place called the Cabaret Voltaire, the rejection of classical western art.
Well, you see this in the nature of what took place at the Cabaret Voltaire.
They didn't put on plays or operas there.
What they did was throw out all conventions.
They mixed everything and anything together.
They would, they might start with somebody reading a poem then somebody else playing an instrument followed by a display of paintings followed by somebody else chanting followed by somebody else banging on a big drum and someone dressed in a robot costume jumping up and down.
So it's not like a play.
There's no real plot development here like you'd find in traditional theatrical performance.
The performers at the Cabaret Voltaire would also get the audience involved which was extremely unusual.
Think about a traditional play.
The action's self-contained.
The actors act as if there's no one watching, right?
It's like a world unto itself.
Well, at the Cabaret Voltaire, audience members could get up on stage and dance or chant or shout and sing from their seats.
And every night would be different because there would be a different audience and a different set of acts and displays.
So, all this could get pretty chaotic, no barriers between the performers and the audience and no barriers between kinds of art either.
Think about it, poetry, paintings, music, dance all on the same stage and often at the same time.
This is what the Dadaist had in mind when they set out to make art that reflect their own idea of reality.
It didn't make sense.
But why should it? "
L34L2
"Listen to part of a lecture in an Environmental Engineering class.At the end of yesterday's class, we were discussing landfills and hundreds of millions of tons of everyday garbage which are deposited into them each year in the United States.
It's a growing problem.
Quite simply we're running out of space to put our garbage.
And this is especially true for solid organic waste: food scraps from home or food processing plants, waste from farms that sort of thing.
Did you know that two-thirds of the waste sitting in our landfills is organic material?
We have government recycling programs for materials like plastic, glass and metal.
Yet wide spread solutions for organic waste materials haven't really been addressed in the United States.
I think this is just asking for trouble in the future.
So, today I want to talk about a technology that offers a potential solution to the problem: anaerobic phased solids digestion or APS digestion.
First of all, what does anaerobic mean? Anyone?
Without oxygen?
Correct. APS digestion uses anaerobic bacteria, ones that thrive in the absence of oxygen, to consume, to break down organic material.
Excuse me, Professor, um, those anaerobic bacteria you're talking about, well, aren't anaerobic bacteria also used in wastewater treatment plants?
Yes, in fact, they are.
Would you like to explain this to the class?
Sure, so, when wastewater is treated, one of the by-products is a thick liquid called sludge.
And aren't anaerobic bacteria used to break down the sludge?
That's right. Anaerobic bacteria have been used in wastewater treatment for decades.
So how was this technology different?
Good question.
Uh, the anaerobic digestion systems used in wastewater plants are designed to treat sludge not solids.
Now, in the past, researchers have attempted to treat solid organic waste with that same equipment but there was always problem.
In order to process solid waste, the kind we find in landfills, you had to pre-treat the solids to turn them into sludge:
first by breaking the material apart mechanically into small particles and then adding a lot of water until you got a kind of thick soupy mix that the equipment could handle.
But that extra step took time and required a lot of energy.
That sounds like it would cost a lot.
That's right. But APS digestion is designed specifically to handle solid waste so it's much more cost-effective.
The new technology processes organic waste in two phases.
Remember, APS stands for anaerobic phased solid digestion.
First, the waste material is loaded into a large closed container along with different types of anaerobic bacteria.
The bacteria break the solids down into acids and hydrogen gas.
The hydrogen is extracted and the remaining acids are transferred into a different container for the second phase of the process.
There another type of bacteria converts the acids into methane gas.
Aren't hydrogen and methane gas bad for the environment though?
The answer in this case is no because they don't escape into the atmosphere.
The gases are captured and can be burned to produce electricity which saves a lot of money and ultimately decrease our need for fuels like petroleum and coal which are not only expensive but are also polluting.
So organic waste from landfills could be processed this way?
It's certainly one possibility.
And APS digestion systems are very versatile.
They can be installed just about anywhere.
See, anaerobic digestion systems used in wastewater treatment plants are huge tanks that hold thousands of gallons of wastewater.
But the APS container is small enough to be set up on site where the waste is generated, like, uh, food processing plants or on farms.
So garbage doesn't have to be transported long distances.
As a matter of fact, a couple of universities successfully set up demonstration projects.
They collected food scraps from dining halls and local restaurants and processed them in APS facilities.
Not only did the universities save money, we're also learning even more about the APS process.
What's the next step forward?
Well, APS digestion uses several different types of anaerobic bacteria, right?
So what are the most efficient bacteria in the process?
If researchers can figure that out, the highest performing bacteria mix for a system could be determined.
Ultimately, the goal would be to grow enough of these particular bacteria to support large-scale commercial APS systems. "
L34C2
"Listen to a conversation between a student and her Creative Writing professor.Hello, Professor Thompson, can I talk to you for a minute?
Oh, hi, Laura, we missed you last class.
Yeah, I was sick for a few days, um, I was wondering did I miss a lot of work?
Let's see, well, we discussed the story that you've been assigned to read for class, A Memory by Eudora Welty.
And then we listened to a recording of an interview with Welty.
The recording's on reserve at the library, you'll need to listen to it.
Uh, so, did you have a chance to read the story?
Yeah, I did.
What did you think?
Well, I was a little surprised, I mean, the first time I read it, anyway.
What surprised you?
You know, it just seemed like there was nothing going on in the story, I mean, a girl that just sitting at the beach thinking about one of her memories and, at the same time, she's watching other bathers on the beach and sort of just thinking about what they're doing, too.
And that's all that happens, so at the end of the story, I thought, ""That's it?""
I know what you mean.
There's, uh, no surprise ending like in O.Henry's story ""The Gift of the Magi,"" or some big adventure like in William Faulkner's ""The Bear"".
So you didn't like the story?
Well, actually, while I was reading it the second time, I sort of realized that you don't need surprises or excitement to have a great story.
The girl's memory and stuff she was thinking about while she was watching the other people on the beach were really interesting to read about.
And, you know, it made me think that when I write my story, the one we have to write for this class, I can maybe use my own memories to get me started.
Well, in fact, I'd hope you'd see that.
Of course, there are many levels to this story, but what I really want the class to take away from it was that you don't need to write about the great, the exciting world when you write your stories, uh, even writing about a memory can work.
Like I could write about one of times I took a walk in the woods when I was a kid.
Exactly! You know, as the due date of your story approaches, I'm hearing from a lot of students of their worry because they don't have anything exciting enough to write about.
But Welty said in the interview we listened to and in her autobiography that her worst stories were the ones where she tried to write about people and places that were unfamiliar to her.
That's why a lot of her stories are set in Mississippi where she's from.
Welty stresses that, for her anyway, familiarity with her subject matter was the key to a successful story.
Familiarity, that makes sense, thanks, Professor Thompson.
No problem, uh, don't forget to listen to that recording. "
L34L3
"Listen to part of a lecture in a Botany class.When we talk about pollination ecology, we're talking about the relationship between a plant and its pollinator.
From the plant's perspective, the ideal pollinator is an animal that is under-fed, ready to eat and in a hurry.
The pollinator, on the other hand, wants to remain well-fed with as little effort as possible.
These factors help drive the evolution of plants and their pollinators, both of which depend on this balanced and delicate relationship.
Sometimes only certain insects or birds can pollinate certain plants species.
So, to really understand pollination ecology, both the flower and its pollinators must be studied.
Let's start with flowers.
There are several important factors associated with pollination: when and how often a plant flowers, how long the flowering cycle lasts, and the number of flowers that open at the same time.
For example, flowering may coincide with the migration of a certain animal species that pollinates the plant or producing many flowers at once may increase the number of pollinators a plant attracts.
Other characteristics of the flowers are also important: features such as color, scent and shape attract pollinators as does the reward in the flower, the pollen or the nectar that feeds the pollinator.
For example, flowers that attract bats tend to be green- or cream-colored, because visibility isn't important.
Bats are practically blind, remember.
And these flowers bloom at night when the bats are active.
Now, there's a flower in the Amazon rainforest called a royal water lily and the characteristics of its flowers change during the pollination process.
The royal water lily uses color, temperature and scent to attract the beetles that pollinate it.
When the flowers of the royal water lily first open up, when they first bloom, they're white, they also emit a strong odor and their temperature rises.
Producing heat serves two purposes: it magnifies the scent of the flower and it helps the beetles maintain their body temperature.
When a beetle arrives at the flower, the flower closes around it for about 24 hours so that the beetle becomes covered with pollen.
Then when the flower opens, its color changes to red and it cools down.
When the beetle flies out, it carries the pollen to a different heated, white, fragrant flower.
As you can see plants go to a lot of trouble to attract attention.
So what kind of attention are they attracting and why?
Well, sometimes flowers provide shelter for insects, a place to lay eggs, for instance, but usually the attraction is food, nectar and pollen.
Nectar's mainly a sugar solution while pollen is a grain made up of part of the plant's cell structure.
In both nectar and pollen production, quality and quantity vary over time but they're always related to the needs of the pollinator.
You can see that the relationship between pollinators and plants are delicate.
So any number of factors can disturb them.
Uh, human development is one and agriculture is generally believed to be the most harmful.
It can fragment habitats in a variety of ways reducing the number of pollinators which, in turn, may reduce the number or size of the flowers which, of course, affect the animals that feed on them.
Uh, exotic plant species not native to the area can move in and compete.
Even bees brought in to pollinate crops can alter natural pollen dispersal system of rainforest plants.
On the other hand, recent studies have shown that the disruption of one aspect of the pollination cycle doesn't usually lead to the extinction of other species.
It turns out that plant-pollinator relationships are more adaptable to change than we thought.
So, really, it's hard to know just how agriculture affects the pollination of plants. "
L34L4
"Listen to part of a discussion in a Business Management class.Last week we were talking about innovation in businesses.
Remember the graph I showed you?
The curve that looked sort of like the letter S?
Right, Cathy, let's take another look.
Do you recall, Cathy, how this S-curve represents the life cycle of innovation?
Sure, starting on the left, the new innovation, uh, let's say it's a new product.
Almost nobody has heard of it or at least nobody takes it seriously.
Then its popularity increases, uh, slowly at first, till sales really started accelerating quickly.
There were the line goes up steeply in the middle as more and more people get excited about the product and they go out and buy it.
But eventually, moving over to the right side there, interest began to fade and the growth in sales levels off.
At which point the market has matured for that product.
We can still sell it and even marginally improve it but it's not new anymore.
It no longer offers exciting growth opportunities.
So a business leader might face a choice: either stick with this old safe proven idea or move on to the next big idea, a fresh innovation.
But innovations are risky.
They may succeed or they may not.
OK, a case study, George, I've heard your Thursday night program on the campus radio station.
You like jazz, right?
Huh? Uh, yeah, sure, but what?
OK, stay with me here.
On your program last week, I heard an old Miles Davis'album.
Tell us about that.
Uh, Miles Davis, trumpet, I played a CD of a jazz classic he recorded in the 1950s called Kind of Blue.
It's my all-time favorite of jazz recording.
Mine, too. Would you call that recording innovative for its time?
Absolutely! Nothing at all like what he'd recorded up till then, I mean, before that Miles Davis played things so complex that, well, nobody could touch him.
But this was something totally new.
Suddenly his playing sounded so amazingly simple.
And how did people react to this new sound of Miles Davis?
Well, some were disappointed even angry that he'd abandoned his old style.
But soon most of his fans came around.
And this new style appealed to a whole new group of jazz listeners.
I guess so!
Kind of Blue became the most commercially successful album in the history of jazz.
So is there a lesson here, anyone?
Think of that S-curve I showed you.
Oh, so his old style of jazz was actually a kind of product, one that had been developed pretty thoroughly.
And he'd taken it about as far as he could.
So he decided to take a big risk and try something totally new.
Exactly! Something completely fresh and cool and people couldn't get enough of it.
It was a brand new beginning that left lots of room for further development artistically.
And as a market analyst, you could say that with Kind of Blue he was jumping to the beginning of a brand new S-curve, with all that potential for profitable developments still ahead of him.
But let me ask you something else.
This isn't just the music of a single performer, is it, George?
Hardly, more like a group of All Stars, along with Miles Davis on trumpet, there's Bill Evans on piano, John Coltrane on tenor saxophone.
Individually perhaps the best in the business but thinking of Miles Davis as the leader of this group, how did he organize and manage all this incredible talent?
Well, he'd lay out the general outline, the theme, and then give each of these star performers, one by one, a creative freedom to really show what they could do with it on their own instrument, to improvise and add something new, but always within the same general theme.
So Miles Davis gets credit for recruiting the best jazz talent anywhere and getting them to collaborate on a fantastic musical product.
Everyone see the business parallels here?
And give each of these musicians credit for seizing the opportunity and creating great individual performances.
But good jazz is more than just outstanding individual performances, isn't it?
Definitely! Jazz musicians need to listen to each other and go with the flow, like, one time somebody goofed and came in a little early, but everyone else adjusted and went right along with it as if nothing were wrong.
And this mistake came out like just another unexpected creative interpretation.
Thanks, George, great insights, ones that would certainly apply at what we're studying here. "
L35C1
"Narrator:Listen to a conversation between a student and a counselor.Student: Hi, I’m Tina Molly.
Employee:Oh, Tina, yeah, good to meet you!You told me on the phone that you are looking for a part-time position?
Student:Yeah! My roommate works at the dining hall, and she heard a part-time job might be opening up there for this new semester. So I was hoping...
Employee:There was one, but that got filled a couple days ago.
Student:Oh, no! Really? The thing is I've got to do something to pay for expenses.
And, well, I'm not afraid of hard work.
Employee:I guess not.
You see, I always have to check the class schedules of potential applicants to make sure they are full time students in good standing.
And your schedule this past semester, I mean, everything from computer science, to African history, to zoology and physics.
How do you manage with such a heavy class load?
Student:Pretty well! Actually. If I do get a job, of course, I may have to cut back to a more normal schedule.
But, you know, there're so many great subjects to learn about.
Employee: Ah, a generalist.
Student:Yeah! It's gonna be hard for me to pick just one thing to specialize in.
Employee:Say, that gives me an idea. You're pretty comfortable on a computer, right?
With learning new software applications?
Student:Sure! I’m pretty good at that. Why?
Employee:Well, last week I got a call from the folks over at the visualization project.
They wanna add a couple part-timers to their staff.
Student:Visualization project?
Employee:Yes, they help professors from all different departments turn information into something their students can see.
You know, instead of just writing on a black board, more and more professors want to project information onto a screen.
And how do I say this? Some professors are really good in their own subject areas, but when it comes to computers, well...
Student:I get the picture. So they use the visualization project to create what? Like graphs of different sorts?
Employee:Right,Graphs of economic trends for instance or population growth.
And sometimes dynamic maps, maps that change on screen to show for instance how trade ebbed and flowed over the centuries along various routes between China and the Mediterranean.
Student:Wow, that'd be interesting.
Employee:Yeah! And that's just what they do for classroom lectures.
A project staffer might also be asked for to help professors pool together some of their research data and model that visually.
They claim that putting their research in a map,
for example, or a moving image helps them see connections, new relationships in data on, say, animal migration patterns that they might miss if they're just looking numbers on a piece of paper.
Student:That's terrific! What about working hours?
Employee:They are pretty flexible.
Staffers can go in to work day or night.
They just have to make sure it's all done by the time the professor needs it. So shall I give you the number to call to get in touch with these people?
Student:Oh, would you?
To think I came in just hoping to get something in the dining hall. "
L35L1
"Professor:Before we leave the topic of animal navigation, let's look at one more species and how it finds its way through its environment.The species we'll look at is the blind mole rat.
Blind mole rats are interesting in terms of navigation because they live entirely in the dark-in elaborate underground tunnel systems.
So how do blind mole rats find their way around in these complicated tunnels?
Well, for some time we've known that blind mole rats use some combination of two different navigation systems.
Um, one system relies on their sense of time and their ability to remember underground landmarks.
For example, let's say a mole rat wants to find its way through its tunnel system back to its nest where it sleeps.
Well, it goes along. Then it feels some hard stones or a tree root under its feet and it basically says to itself.
""Ok, here is where I took a left."" And then it might remember how long it took to get to the next turn and so forth.
The mole rat goes straight or turns based on what it remembers having sensed along the way on previous trips and the time it took between turns.
Now, the other navigation system for the mole rat relies on Earth's magnetic field.
Mole rats have the ability to sense the magnetic field and use it to orient themselves directionally.
But until recently scientists weren't sure about the role of these two different systems.
Recently a team of researchers conducted an experiment to answer that question.
Do these two navigation systems play different roles?
What they did was they designed a special structure that very closely resembles a blind mole rat's tunnel system, which looks like a bicycle wheel, a central hub with multiple spokes radiating outward.
Now this turned out to be quite important.
Earlier experiments have used a more generic habitat, basically a wide open circle, which was originally designed to test magnetic navigation in other animals.
That design led to inconclusive results with mole rats.
Now, with their bicycle wheel tunnel system the researchers were able to vary the distance that the mole rats travel between their nest and their food source by creating long routes and short routes.
In each trial, the mole rats started out in their nest, went to the food source and then had to find their way back home, back to the nest.
To determine which navigation system they were using, the researchers tested the animals under two different conditions.
First, the mole rats were tested under conditions of normal magnetism for both the trip to the food and the trip home.
And under these normal conditions, they all followed their original route back home, regardless of the length of the trip to the food source.
Then in the second part of the experiment, the magnetic field was altered but only for the trip home, a specially constructed set of magnets was used to shift the magnetic field around the habitat 19 degrees eastward.
The researchers wanted to see how the mole rats responded to this shift.
Well, it turns out that the magnetic shift had no impact on the return route of the blind mole rats after a short trip.
They returned to the point where they had started from.
But after a longer trip, they took a totally different route: one that led them nine degrees east of the nest.
Essentially they got lost. This was strong evidence that blind mole rats use magnetic navigation only for longer trips.
So why two navigation systems: one for long trips and one for short trips?
Well, for now we can only speculate, but we think that when mole rats rely on the first system, using underground landmarks or their sense of time, well, they make small mistakes here and there.
On a short trip, this doesn't matter much. The trip is short, so they can't make many mistakes.
But on a long trip, well, there are lots of opportunities to make small mistakes, and small mistakes can add up, leading the mole rat far from where it wants to be.
So on a long trip, a magnetic navigation system is better, more useful, since earth's magnetic field is stable, a constant, a more reliable indicator of direction. "
L35L2
"Narrator:Listen to part of a lecture in an archaeology class.Professor:One of the frustrating things about archaeology, especially for beginning students,
is that theories are constantly evolving.
A theory that's been accepted for many years may suddenly be called into question.
Student:But why would that happen?
Professor:There are probably a number of reasons.
Earlier finds are always being reexamined in the context of new finds.
Or it may just be that someone looks at the evidence in a different way, has a different idea of what it suggests.
Take the theory about the earliest permanent settlements.
They were found in an area to the east of the Mediterranean Sea called the Levant.
And the people who lived there were the Natufians.
For quite some time, it's been widely accepted that about 15,000 years ago,
the Natufians developed a sedentary lifestyle.
Can someone remind us what that means?
Student:It means that they stopped being nomadic,
that they began staying in one area year round instead of moving around all the time.
Professor:Right. And we think there was an abundance of edible plants and animals in the area at that time
that make this shift away from a nomadic lifestyle possible.
Uh...keep in mind that the Natufians were hunter-gatherers.
So in spite of other changes, they were always a pre- agricultural society.
Anyway, after being sedentary for around 2,000 years,
something happened that forced the Natufians to change their lifestyle.
The general consensus is that there was a period of climatic cooling,
which had a negative effect on the availability of food.
And this food shortage likely caused the Natufians to revert to a nomadic lifestyle.
Then around 11,500 years ago, the climate warmed again.
Food became more abundant and the people in that area became sedentary again.
Now, no one is contesting that these people,
probably descendants of the Natufians, were indeed sedentary by 11,500 years ago.
The evidence is quite strong.
Archaeologists have uncovered numerous circular structures dating from that period
that appear to have been used to store grain.
We think this for a couple of reasons.
First, the remains of barley houses have been found inside them.
Barley was the main type of grain that grew in this area.
And secondly, the floors on these structures were elevated.
This design would have been consistent with the need to keep the barley dry and safe from rodents.
So, that makes sense.
And there are lots of these structures in the settlements.
In one settlement that was only partially excavated,
archaeologists have already found four of these structures.
Student:So it's the earlier part,
that the Natufians were sedentary 15,000 years ago, that's changed?
Professor:Well, there's evidence,
but some archaeologists have questioned the criteria used to identify permanent settlements.
See, circular structures have also been found in early Natufian settlements,
so archaeologists believe that
these were also food storage structures based on their physical similarity to the structures in later settlements.
And they would indicate that the Natufians were sedentary 15,000 years ago.
But now, there are doubts about the use of these earlier structures.
Researchers point to the lack of grain remnants in these earlier structures.
In fact, things other than grains have been found in them.
So at the very least, they say, these structures probably had multiple purposes.
And another problem they point to is that most early settlements have only one of these so-called storage structures.
But do you think one structure would be enough to hold the surplus for an entire settlement?
Student:Well, whatever these structures were used for,
couldn't they just have built them at a place they came back to regularly?
Maybe to store things for their next visit?
Professor:Exactly! So-called base camps, where the Natufians didn't stay all year round.
But artifacts that were found at a number of Natufian sites seem to present evidence of a sedentary way of life.
Large heavy mortars, the sort of thing that would have been used for grinding grain.
Such heavy equipment could indicate that the Natufians would have stayed permanently in one place
since the work involved in moving an item like this around constantly would have been substantial.
But this evidence of sedentism has also been called into question
because the materials used to make the stone mortars did originally come from quite a distance.
And if the Natufians could move the materials over great distances... "
L35C2
"Professor: So I wanted to talk about your outline.I do like your topic: William, the conqueror, leading the Norman invasion of England.
But I'm a little concerned about your source and the fact that you want to use it as the entire basis of your paper.
Student: Really? The Bayeux tapestry? I thought it was pretty creative to use something that was made to hang on a wall as a source.
And as far as I know it's the most important documentation of the invasion, a first-hand account, right?
Professor: Well, you are right. It's considered a primary source.
And at 70 meters long, the tapestry certainly is impressive.
Imagine the time it took for those embroiderers to sew all those words and images to tell the story of the Norman forces sailing from France to England.
So, yeah, it's an amazing artifact, but what’s problematic is that the tapestry is a very controversial source. Were you aware of this?
Student: Well, I know some pieces of it were probably lost.
Professor: It is incomplete, but...
Student: But I also read that historians have relied on it to help interpret the events leading up to the invasion and the battle itself.
Professor: Well, it has great historical value, no doubt, but in my opinion, there's a problem because...well...do you know who commissioned the tapestry?
Student: It was a church official...um...the bishop of Bayeux, a city in France?
Professor: Yes. And the bishop was also William the Conqueror's half-brother.
Student: Oh! That I didn't know. But regardless of who commissioned it, isn't the fact that it was based on eye witness accounts the most important thing?
I mean, it was made only 17 years after the battle. So plenty of eye witnesses were still alive.
Professor: Yes, that's true. But the real point of the controversy isn't the battle itself.
It has to do with the reason for the battle: who was the rightful heir to the throne?
Who would be the next king? And if William the Conqueror's brother is the one who's commissioned this tapestry...
Student: Then he would be the one to decide which words and images would go on the tapestry and what would be left out.
Professor:Exactly. So of course the tapestry shows why William should be the new king.
Student:I guess I see your point. Embroiderers are just gonna do what they are told to do.
Professor:You have to understand that the tapestry depicted an entire series of events as they were interpreted by the Normans, the victors of the battle.
And that's a problem if you are trying to write objectively about the invasion, especially if you use it as your only source of information.
After all, it's important for historians to examine an event from all sides. "
L35L3
"Narrator: Listen to part of a lecture in an art history class.The professor has been discussing the Italian Renaissance.
Professor: In our discussion of Italian Renaissance paintings from the 1400s and early 1500s,
we've looked at some masterpieces on canvas and on wood,
but our discussion will be grossly incomplete without talking about frescos.
Frescos are basically paintings done on the interiors of buildings, on walls and ceilings.
They weren't invented during the Renaissance.
If you remember we looked briefly at frescos paintings way back in our discussion of ancient Romans and ancient Roman art a few weeks ago.
But, it was much later during the Renaissance that the term fresco was commonly used.
It's an Italian word that means literally fresh.
And, well, to explain that, we have to get specific about technique.
Back then, most buildings had stone and brick walls with highly irregular surfaces.
They weren't smooth.
Also, the walls weren't completely waterproof.
Moisture could seep in. Buildings were often damp.
There was no way to really control humidity inside buildings in those days.
So, because frescos are done inside buildings on walls,
well, the walls needed to be prepared before work could begin.
So for example, sometimes, thin reed mats were stuck onto the walls,
so these thin reed mats would be like an additional layer between the original part of the wall and the frescos,
the painted part of the walls that were done over them.
The reed mats could smooth out the surface of a rough wall or could also provide that all- important protection from moisture or do both.
So it was the wall, then the mats, then plaster on top of the mats, then the fresco painted onto the plaster.
Other times though, plaster was applied directly to the walls,
a thick layer of plaster, to fill in spaces between the bricks, to smooth out the wall surface for painting the fresco. You see.
Plaster is a whitish kind of paste, a mixture of lime, water and sand.
After you spread plaster on a surface, it'll harden, like cement does.
But as I said, fresco means fresh.
And that's because to create a fresco,
the painting has to be applied very soon after the plaster has been spread over a surface,
right on to the wet fresh plaster.
By doing this, the painting actually becomes part of the plaster.
Finishing a painting before the plaster dry was a real challenge for fresco painters.
The technique of creating frescos was developed overtime and eventually perfected during the Renaissance,
a time when immense buildings were being erected as symbols of wealth and power,
very large buildings, which people wanted decorated on the inside as well as the outside.
The owners of these grand buildings wanted to decorate the walls to reflect their own affluence and prestige.
Now, few people would argue with the greatness of artists from that period, Michelangelo, Raphael.
But there is this popular mental image people have of an artistic genius producing a masterpiece in total solitude.
Well, that idea is fine for canvas painting or other small works,
but a practical reality of fresco painting in the Renaissance was collaboration.
The sheer dimensions of the surfaces involved, plus the physical properties of the plaster,
meant it was inevitable that Renaissance artists would rely on assistants,
apprentices they were called, to help create their masterpieces.
Artists had to plan the work carefully, divide it into several days.
Each day was a repetition of the same technical process.
Apprentices mix paints, prepare the plaster,
spread it on one section of the wall or ceiling,
then finally paint on the wet plaster.
This had to be done within a few hours before the plaster dried.
So they go through that whole process in one day on one section.
The next day they'd move on and do it again on an adjacent part.
So any fresco commissioned to an artist was, for practical reasons, commissioned to a whole team.
Now, I am not saying a genius like Michelangelo lacked the skill to paint the enormous ceiling of The Sistine Chapel by himself,
but he probably would have had to live until he was 200 years old to finish the ceiling's frescos like that without anyone's help.
So although we aren't sure exactly how many people took an active role in actually painting the ceiling, we can see areas which are really inferior to Michelangelo's work that must have been painted by his apprentices. "
L35L4
"Narrator:Listen to part of a lecture in an Earth science class.Professor:Let's review something from last week.
We talked about an event that happened 65 million years ago. Anyone?
Student:An asteroid hit Earth.
Um...well, we think an asteroid hit Earth, near the Yucatan Peninsula, in Mexico, and that wiped out all the dinosaurs.
Professor:Right. I wouldn't say that we've got 100% proof, but there's very strong evidence that this is why that mass extinction occurred.
Okay.But did you know there was an earlier extinction far greater than the one that killed off the dinosaurs?
It was what we call the Permian Extinction.
Now, way back about 290 million years ago, at the beginning of the Permian Period, there was just one big continent, a super continent.
And as the climate warmed up, plant and animal species began to diversify profusely.
So life during the Permian Period was abundant and diverse.
But about 250 million years ago, the Permian Period ended with a rapid mass extinction, something happened that wiped out 75% of the land animals and over 95% of ocean life.
So what was it? What could have caused this?
Well, with the all the evidence that it was an asteroid that led to the dinosaur extinction, we began asking ourselves: is it possible that another asteroid much earlier caused the Permian Extinction?
And so researchers have been looking for an impact crater.
Student:I thought the Permian Extinction was caused by a decline in sea water oxygen levels.
Isn't that what's in the textbook?
Professor:But don't forget the textbook makes it very clear that's only a theory.
Student:And it mentions something about volcanic eruptions too.
Professor:It does, but now this new theory has led to a search for evidence of an asteroid impact.
And one place of interest is a region called Wilkes Land in eastern Antarctica.
A few years ago, a researcher reported a strange anomaly beneath the ice in Wilkes Land.
Evidence of what may be a mascon.
That's just short for mass concentration.
When an asteroid hits Earth, when it slams into Earth's crust, we think that causes molten rock from deep below the surface to rise up into the impact area.
Sort of like if you bump your head, you get a big lump under the skin.
Fluid makes the area swell.
Anyway, the material flowing up from below the crust is more dense than the crust itself.
So that's how we get a mascon, a spot in the crust with newer crust material that's more dense than the material all around it.
There're lots of mascons on the moon too,where a mascon's density causes a small increase in the local gravity that can be measured and mapped by orbiting spacecraft.
And where do these mascons tend to be found?
In the centers of impact craters on the moon's surface.
But back to Wilkes Land.
We're not certain that the mascon there
...what might be a mascon ...was actually caused by the impact of an asteroid, but there does seem to be evidence.
Researchers notice a gravity anomaly similar to those on the moon.
And the spot where the gravity readings are especially high...
this is right in the middle of a 500-kilometer wide, circular ridge, what could be part of an old impact crater.
And if there was an asteroid impact there in Wilkes Land, the next question is: did it happen 250 million years ago?
Because that would put it when in geologic history?
Student: At the end of the Permian Period? Right when those animals went extinct.
Professor:Exactly.
Student: But can't researchers figure that out by studying the rocks there in Wilkes Land...
where this impact supposedly took place?
Professor: Well, to get to anything from that long ago, we would have to drill down to about a mile, about 1.6 kilometers of solid ice that covers the area today.
And that's not likely to happen.
But speaking of rocks, I should mention that Wilkes Land is not the only place of interest here.
There's another called the Bedout High off the coast of Australia.
And we have rock samples from the Bedout High.
Some apparently have extraterrestrial origin.
I mean, they show the effects of extreme temperatures and pressures, the level of extremes produced only by an impact. And as for their age, well, they do in fact, date back to about 250 million years ago. "
L36C1
"Listen to a conversation between a student and her academic advisor.Hi. Professor Jones. Thanks for seeing me.
No problem, Laura. How was your summer break?
It was great! But the fact is it's made me reconsider my academic plans.
Oh, really? Nothing too dramatic, I hope.
No, no. At least I hope not.
What do you mean exactly?
Well, I just spent the summer working on a Native American reservation, a Navajo reservation in Arizona.
And I was fascinated, so now I want to study the Navajo language, uh, their history, religion.
I want to go back next summer too.
And maybe even spend a semester there, some kind of internship or independent study?
Wow! Sounds like you are really enthusiastic, but you were majoring in sociology, and I seem to recall that for your senior project, you were doing something with education?
Right. I have done some research on the public schools in the northeastern states, how they've been affected by changes in population, uh, immigration trends, during the past fifty years.
But now I really want to study the culture of the Navajo people.
Well, there are a couple of options depending on your priorities.
Say, how did you end up on a reservation in Arizona anyway?
Well, a friend of mine took a job there, in a summer school program.
And they had another opening.
Someone cancelled at the last minute.
I thought it would be just a big adventure, but it turned out to be much more than that.
I see. Well, anyway...as I am saying, your options depend on what your priorities are and on exactly what you want to study.
Uh, like I said...Navajo culture?
Well, let's see if we can be more specific.
If you want to study the Navajo language, learn about their religion, their history, that's part of cultural anthropology.
No. I really don't want to change majors at this point.
I love sociology and I really want to graduate in four years.
Okay. Now I see what your priorities are.
So from a sociological perspective, since you are interested in education, you can stay with that, change your research topic to the Native American experience with public education, the effect it had.
And you could take sociology courses on religion or the role of minorities in society, again, focusing your research on the Navajo.
Um...l hadn't thought about that angle.
Sounds intriguing.
And all the courses I have already taken would still count toward my degree?
I have to check.
And remind me to plan carefully to make sure all your degree requirements are met, but I don't see any problems.
Great! And then I can pick up the language and culture courses as electives. "
L36L1
"Narrator: Listen to part of a lecture in an environmental science class.Professor: Now last week when we discussed the serious energy challenges we are going to face as the world's population continues to grow and we place more stress on our finite supply of fossil fuels, especially natural gas and oil, well, maybe it's not all doom and gloom.
In a number of areas, scientists are thinking outside the box and trying to come up with unusual, novel solutions to the energy question.
Not that a positive outcome is inevitable by any means, but well, let's take a look at one of these creative ideas involving a gas - helium-3.
Helium-3 is an isotope of helium that has tremendous potential for use in practical energy applications. Remember, an isotope is a form of a chemical element that has the same number of protons in its atomic nucleus but a different number of neutrons.
The most common isotope of helium on Earth is helium-4, which does not have any known or potential uses as an energy source.
Helium-3, in comparison, is extremely rare.
There isn't very much of it on Earth.
Plus, the, um, the main source of helium-3 in our solar system is solar wind, a stream of lethal radiation and particles pouring off of sun.
And Earth's magnetic field fortunately prevents that wind from reaching us.
So why is helium-3 so exciting?
Well, it seems a sure bet that helium-3 is available in abundant quantities on the moon.
Since the moon doesn't have a magnetic field, the solar wind must have been depositing helium-3 there for billions of years.
In fact, Apollo astronauts have already discovered it in the moon's dust.
Some estimates hold that there may be a million tons of helium-3 buried on the lunar surface.
And one ton is more than enough energy for a city of ten million people for a whole year.
So you can see this would certainly solve most of our energy problems.
But how could this be possible?
Well, we think helium-3 would have to be used in nuclear fusion reactors.
Keep in mind that a nuclear fusion reactor is completely different from our existing nuclear fission reactors.
Basically a nuclear plant powered by nuclear fission derives its energy from the splitting of atoms.
While a plant based on nuclear fusion utilizes the energy produced when atoms are fused together.
Fusion is the same nuclear reaction that fuels stars, which as you know, produces unfathomable amounts of energy.
Researchers have identified two isotopes of hydrogen as the most promising fuel sources for fusion power plants.
However, there is a real drawback.
They both produce large amounts of radioactive material in the fusion reaction.
But helium-3 fusion produces no radioactive material.
In fact, one proponent stated you could safely build a helium-3 power plant in the middle of a city.
A clean, safe source of power almost sounds too good to be true, doesn't it?
Well, of course, this is all very theoretical.
And there are issues that have to be addressed.
For one thing, we still haven't created a single nuclear fusion plant despite decades of research and development.
An often heard joke about fusion is that a nuclear fusion plant has been just decades away from being created for several decades now.
Nuclear fusion research is still ongoing, as strong as ever, in fact, but we still don't have a full- scale fusion plant to point to.
And there's a rather big logistical problem as well.
How to get the helium 3 off the moon?
Digging the stuff up is challenging because the distribution of helium-3 is so diffused across the lunar surface.
One estimate is you'd need to heat a million tons of lunar soil to about 800 degree Celsius to yield about 70 tons of helium-3 gas.
It's kind of liking digging out a crater with a spoon to find the single nugget of gold. Kind of ridiculous, right?
There's a camp that believes it'll take more energy to extract helium-3 gas than the gas itself would provide.
So there are concerns, but given the lure of the possibilities and the pressing nature of our energy difficulties, it’s possible that helium-3 could be a significant driver of future exploration of the moon.
And it certainly could ease the pressure on the demand for fossil fuels if and when the numerous challenges, and not just the ones we've talked about, are solved. "
L36L2
"Listen to part of a lecture in an archaeology class.Professor: Sure. Sometimes we do just stumble onto an important find when doing field research, but usually we've got at least a vague idea of where to look.
And with new technology...uh...Okay.
Here's a story that illustrates what I mean.
It's about the Mayans, who, as you remember, flourished in Central America and had a culture that was quite advanced in art, architecture, astronomy...
We know that despite regular droughts and poor soil, their numbers grew into the millions over the centuries until about 1,200 years ago when their entire civilization just seemed to disappear, and we are not sure why.
Okay
So an archaeologist named William Saturno1 goes looking for ancient Mayan ruins in Guatemala near a town called San Bartolo.
And after several days of extremely difficult hiking through the thick rainforest, Saturno stops to rest in the shade and finds himself sitting in what turns out to be an ancient Mayan temple, a pyramid 25 meters high.
And inside, on the walls of this temple, Saturno finds some ancient writing and also this enormous mural with elegant figures depicting a Mayan myth of the creation of the world.
And it’s all painted on plaster that's over 2,000 years old, which makes it the oldest Mayan artwork ever found, at least in good condition, and in fact, one of the most perfectly preserved and extremely important find.
Student: Wow! Do you have a picture of it?
Professor: Now...hang on.
I don't...there's a point I want to make here.
It happens that someone at NASA, the United States Space Agency, reads about Saturno's discovery and gets very excited 'cause the space agency has just produced some images of this area using a technique called remote sensing.
That's when instruments on planes and satellites survey areas on the ground.
And the newest twist on remote sensing, quite new, is infrared imaging.
Instead of taking regular photographs, the satellite cameras take pictures using infrared light, which is invisible to the human eye, but computers can then process these images so our eyes can see them.
Using infrared imaging, the satellite-based remote sensing instruments revealed what turned out to be traces of water storage systems and canals, canals that the Mayans built to irrigate their parched soil, which helps explain how the Mayans could feed such a large population.
The infrared images also revealed ancient roadways that had tied Mayan cities together.
So people at the space agency figured Saturno would be interested and they sent him this infrared image of the area near San Bartolo where the pyramid temple was found.
Now, this is a false color image based on an infrared photo.
So the greens of the jungle are shown mostly as blue and red, but notice also the spots of greenish yellow scattered here and there.
These indicate significant discoloration in the vegetation, at least as it appears to infrared cameras. And Saturno notices that some of that discolorations located in exactly the spot where he found the pyramid temple.
So he figures, hey, maybe some of those other yellow spots are worth investigating.
Well, long story short, he checks out three different spots where the photo shows discoloration and finds an ancient Mayan site overgrown with vegetation at every single one.
Further exploration shows a perfect correlation between yellow spots on the infrared image and Mayan ruins hidden in the jungle.
Student: So what caused those spots to look different?
Professor: Well, Saturno believes the limestone and lime plasters that the Mayans used to build their structures...
Over time, uh, this limestone decayed and seeped into the soil and changed the soil's chemistry.
Then calcium carbonate from the decaying lime plaster might have been taken out by the roots of the trees growing there, uh, up into their leaves, and made them give off infrared light much more brightly than the surrounding vegetation.
And infrared sensing technology can detect this.
Student: So…like…is Guatemala the only place where archaeologists have used remote sensing?
Professor: No. This technique has been used in other parts of Central America too, and also in Brazil, Bolivia, Cambodia.
It can be used anywhere the rainforest has obscured ancient ruins.
And the results can be amazing! Like another Mayan temple that Saturno found, thanks to remote sensing, he had walked right by it every day for five years and had no idea it was there, until he saw an infrared image of the area! "
L36C2
"Narrator: Listen to a conversation between a student and the program manager of the university radio station.Student: Hi I'm Jim, the guy who’s trying to get a new show.
Manager: Right. Jim.
Student: My application got turned down and...um...l am not sure why.
So I wonder if you could explain...
Manager: I’m glad you came in, Jim.
I was actually quite impressed with your application.
Student: Okay.
Manager: But the thing is, we run a music station here, not a talk station.
We've been a music station since the beginning, since the station's inception.
Student: This is where I get confused because of the article in last month's campus newspaper about the poll...
Manager: Yes. The survey...
Student: I mean, a majority of students said they felt the station was stale, that it needed a breath of fresh air.
Well, um, how are we supposed to get fresh air if you keep all the windows closed?
I was just trying to open some windows for people.
Manager: I can tell you have a lot of passion for this, but I’m really not convinced it’s a good idea. Okay.
The first thing is, again, this is a music station.
If we just have that one calling show, it just doesn't fit in with what we are doing.
And studies have showed that mixed format stations just aren't as successful as...Look.
We do want to innovate, but within the format.
And with a live calling show, for one thing, you have no idea what the caller is going to say, no idea what you could end up broadcasting.
Student: I understand, but that seems like a small risk to take in exchange for giving students a chance to talk publicly, interactively about issues they care about.
I really think they'd like to have a place where they can air their views about current events, about the university.
Manager: But the university already has that.
There's a monthly meeting open to all students to discuss issues like the ones you mentioned in your application.
And there are several student clubs on campus that discuss current events.
But either way we have no plans to change the format.
Now, if you had an innovative idea for a new music program...
Student: Well...how about a music program that includes taking calls from listeners?
Manager: You really are determined to have a calling show, huh?
Student: Well, I'm a communications major, and I'm hoping to get an internship at a professional talk radio show in the city next year.
I thought a little experience with the college station might help.
Manager: Tell you what, there's still some time before the application deadline.
Why don't you submit a new application with the music show idea that you just proposed?
Then we will see if we can work something out.
Student: Okay. Thanks! "
L36L3
"Narrator: Listen to part of a lecture in an architecture class.The professor has been discussing housing designs.
Professor: Alright, in our last class we began our discussion of housing designs in the United States from the 1940's.
You'll remember, for example, that we looked at some photos and discussed apartment complex in Chicago from that decade.
Now, today, let's talk about housing design in the suburbs.
The demand for low-cost housing outside the cities increased in the late 1940's after World War II as a whole generation of young families needed affordable housing, and a firm called Levitt & Sons strove to meet this demand in some pretty innovative ways.
They designed buildings based on the demands of the public, not so much their own artistic vision, and created a residential community in the state of New York that became known as Levittown.
Levittown was the first suburb of its kind and it started out with 2,000 homes.
They were called ""Cape Cod houses"", the ""Cape Cod model"", and they were designed to look like the historical cottages in the New England states in the northeastern United States.
The original floor plan was very simple.
The living room was in the front of the house with windows looking out towards the street.
You also had two bedrooms, um, a bathroom and a kitchen. Everything was on one floor.
The bathroom was right next to the kitchen, which was a way of keeping building costs down since the two rooms could rely on just one plumbing system.
Another feature of this Cape Cod house is that it could be expanded as families grew and needed more space.
You had the downstairs but up the stairs the house actually had unfinished attic space as well.
Levitt & Sons promoted their houses saying this attic space could easily be converted into another bedroom or even two, and then there was always the possibility of building additional rooms onto the house later.
Each house was built the same way and with the same materials.
All parts were standardized so houses could be built economically.
This was important because it meant that they were affordable for young families who wanted to live outside of the city.
As a result, what you had was a whole community of houses that, except for the color of their roof and walls, were identical.
So eventually there's going to be a demand for some variety, right?
After a couple of years, Levitt & Sons came up with a second design.
Well, they called it a second design because it had a slightly different roof.
Plus, the exterior had a more modern look.
This model was called a ranch house.
Now, I'm guessing it wasn't too expensive or time-consuming for Levitt to come up with this idea, but it was certainly efficient and hugely popular with families.
The Ranch is like the Cape Cod except that the living room is in the back of the house instead of the front, and on this Ranch model there is one more important feature that is not present in the Cape Cod.
It has a large window in the living room called a ""picture window"", which gives you a kind of ""framed view"" of the outside.
The way the Ranch is set up when you look out this picture window from the living room you're looking out from the back of the house instead of from the front.
Parents could watch the children playing in the backyard, the grassy area behind the house rather than a view of the street.
So here was a way for families to disconnect their home, their house, their private lives from the outside world, which was represented by the street that led to work and school, which really seems like the thing they had been looking for all along, but the floor plan was just like the Cape Cod only, you know, turned 90 degrees.
Levitt & Sons offered their ranch houses for sales at a low price.
They could do that because they were using the simple and therefore cost-saving building methods.
Another way they kept construction prices down was to train workers who went from house to house doing a specific task, sort of like an assembly line.
For example, you might have a painter whose job was to paint the doors of each house and then it would be someone else's job to install the doors.
This way houses went up quickly, saving time and money. And the Levitt's ideas caught on.
In the early 1950's, their designs became a model for suburb construction throughout the country. "
L36L4
"Narrator: Listen to part of a lecture in a biology class.Professor: OK. Back in the 1930's, a biologist named G.F. Gause first proposed what's known as ""Gause's hypothesis"".
Gause said that whenever you've got two similar species competing for the exact same limited resources, one of them will have some sort of advantage, however slight that'll eventually enable this species to dominate and ultimately exclude the other one, even cause it to become extinct.
That's why Gause's hypothesis came to be called ""The competitive exclusion principle"".
Gause did some lab experiments like placing two Paramecium species in the same environment where they would have to compete for the same food.
He found that, over time, one species was consistently able to drive out the other, to eliminate it from the habitat, just as his hypothesis predicted.
Now, one of the early criticisms of Gause's hypothesis was that: ""sure, it works in simple lab experiments where you have just two competing species in a controlled environment, but the hypothesis falls apart when applied to natural ecosystems where things are more complex"".
Now, it's true that in the real world there are lots of examples that seem to contradict the hypothesis.
For example, in the forest of New England, in the northeastern United States, there are some small songbirds called wobblers and right in the same area you've got five species of wobbler, all about the same size and all having similar diets of insects, uh, insects that are found on and around trees.
Yet, these five wobbler species all managed to coexist.
There is no dominance, no exclusion of one species by another.
How is this possible?
Well, turns out that one wobbler species feeds in the uppermost branches, while others favor the middle branches and others feed toward the bottom of the tree.
Also, each wobbler species breeds at a different time of year.
This way the period of peak food requirement, um, when the birds are feeding their chicks, varies from one species to the next.
Yes, Mark?
Student: But does that really contradict Gause's hypothesis?
Because, I mean, are those different wobbler species really competing for the same food?
I don't think so. I think they're more like, you know, almost cooperating so that they don't have to compete.
Professor: Excellent! To the casual observer, the wobblers do seem to contradict Gause's hypothesis since they all live in the same place and eat the same types of insects.
But if you observe these birds more closely, the wobbler species are not really competing with one another for the exact same food at the exact same time, which brings us to a really important concept in ecology: the niche.
Mark, can you tell us what an ecological niche is?
Student: The place where the plant or animal lives, you know, its habitat.
Professor: For example?
Student: Like the polar bear living in the Arctic on the ice sheet.
The Artie is its niche, the habitat it's adapted to survive in.
Professor: Okay. That's what most people think of.
But for biologists, the concept of a niche also includes the way an organism functions in its habitat, how it interacts with other plant and animal species, with the soil, the air, the water and so on.Okay. Now let's put it all together.
If you have two similar species competing in the same niche, what's going to happen? Susan?
Student: One will dominate the other and eventually eliminate it.
Professor: Okay.
So what could the weaker species do to improve its chances of survival?
Student: Maybe just move to some other area, you know, away from the competitor.
Professor: That's one possibility. But think of the scientific definition of a niche.
Think about the wobblers.Mark?
Student: Maybe it could find some new way of functioning in its habitat so that it wouldn't have to compete with the dominant species.
Keep the same habitat but not the exact same niche.
Professor: Yes, and there are many ways to do that.
The dominant species feeds in one part of the tree and you feed in another.
Student: If the dominant species needs a lot of water you develop the ability to survive on very little water.
Professor: You survive on what's left over: water, food, nesting or breeding sites, whatever. "
L37C1
"Narrator: Listen to a conversation between a student and his anthropology professor.Professor: Well, Mathew. Good to see you. How can I help you?
Student: Did you happen to read last weekend's art section of the newspaper?
Professor: Yes, I did. Why?
Student: Well, you remember the article about an exhibition of ancient featherwork pieces from Peru?
I'm thinking of doing my research paper on this topic, if it's okay with you, of course.
I've done some additional reading about ancient Peruvian cultures, how they used brightly colored feathers to decorate clothes and ceremonial objects.
From the pictures I'm seen, they are beautiful works of art.
Professor: They sure are. I saw the exhibition a few days ago. But is that how you'd approach Peruvian featherwork in your paper?
As an art form? Remember you need to take an anthropological angle.
Uh, look at this in a way that tells us something about the people who made this featherwork and the societies they lived in.
Student: Well, absolutely. I read that most of the really colorful feathers came from the rain forest and the societies who used them lived on the coast on the other side of the Andes Mountains, so the feathers had to be carried over the Andes.
No wonder featherwork was symbol of high status in ancient Peruvian societies.
Professor: That's definitely a long, dangerous trip to make on foot. I do research down in Peru and I have made that trip, but the easy way.
I've flown and driven.
Student: I didn't know you did research in Peru. Maybe...do you think you would be able to help me with this paper?
Professor: I’ll be happy to help if I can, but Peruvian featherwork isn't my area of expertise.
You know, every few pieces of featherwork survive because feathers decay so quickly.
Not many people have had the chance to study them up close. There is a handful of experts out there who have, and I could try to contact some of them.
But I think your best bet is to keep reading and finding more books and articles.
And of course you can use the information you got at the exhibition as source material too. You've been to the exhibition, haven't you?
Student: Uh, actually...not yet.
Professor: Um...well, it would be a good idea if you went, don't you think?
It's good that you've done some background reading, but it will make more sense when you actually see the featherwork.
There's a lot of information available there from book lists, tour guides. And you could even ask to meet with the curator and ask for her insights. "
L37L1
"Narrator:Listen to part of a lecture in the geology class.Professor:So, we all know soil. It's important to plant growth, right?
And we know that there're different types of soil in different places and that some soils are more fertile than others.
But what is soil? And how's it formed? Well, we're going to go into this in some depth, but for now let's just lay down the basics.
Soil is composed of two kinds of material: inorganic material, basically small pieces of rock, and organic material, which is animal and plant matter.
OK. So, what do you think? If I mix bits of rock with composted vegetables, will I get soil?
The answer is no, because the formation of soil is a dynamic process.
It involves not only the initial inputs, the raw materials, but also the transformation of those materials, and the movement of some of the materials and the loss of others. So, the inputs are bits of rock and organic matter.
Now, the bits of rock, the inorganic input to soil, uh...they come from the breakdown of rocks on Earth's surface through a process called weathering.
Weathering can be either physical or chemical. Physical weathering, uh...that's when exposure to the elements over time causes a rock to break up and eventually disintegrate.
Uh... of course, some rocks are more resistant to physical weathering than others.
If you think of the sand particles in soil, those are the result of physical weathering, and they have the same chemical composition as the original rock.
Now, chemical weathering, uh... that's the chemical breakup of rocks.
It differs from physical weathering in that the chemical properties of the minerals are actually changed. The clay minerals you find in soil are the result of chemical weathering.
Clay minerals are called secondary minerals, because their composition has been altered.
Okay. So we have weathered rock, which needs to be combined with organic matter.
So what does the organic input consist of?
It's the remains of plants and animals, but mostly plants.
Now, just as rocks are broken down by weathering, the animal and plant residues are broken down, too.
They're reduced to simple chemicals by microorganisms in a process called mineralization.
And just as some rocks are more resistant than others to weathering, the compounds found in the soil's organic input resist mineralization at different rates.
The compound cellulose is the major constituent of most plant tissue. It mineralizes relatively quickly. But there are woody substances in certain plants that strengthen the cell walls.
They are found in smaller concentrations and their mineralization can take several years.
Weathering and mineralization transform the inorganic and organic inputs in a number of ways.
And it’s partly from these transformations that soil gets its unique properties.
How does it work?
Uh... take the dark brown color of soil. After microorganisms have broken down the cellulose, we're left with two things: the microbe's waste and the more resistant plant material that microorganisms can't break down easily.
These materials ultimately get transformed into a new material called humus. And when humus is combined with the clay minerals in soil, that's what gives soil its dark brown color.
So now, if we've got clay and humus, these transformed materials, and we mix them together, we've got something very close to soil.
But soil isn't static, and there’re still other processes that go into the formation of soil: the movement and loss of materials. The soil in any location isn't a uniform mixture.Its composition varies with depth.
You see, mineral and organic materials move through soil vertically.Some materials move more easily than others.
Water carries the more mobile materials from the upper level of soil to the lower levels.So the upper levels of the soil eventually get depleted of these materials, while the lower levels get enriched with them.
And that creates distinct layers of soil as far down as the rock underlying the soil.
And the materials that dissolve easily in water can get lost completely if the water carries them horizontally out of the soil and into rivers.
Now, of course, new mineral and organic material will be deposited at the surface and become incorporated into the soil, but you see how the processes of movement and loss contribute to the formation of soil. "
L37L2
"Listen to part of a lecture in an archaeology class.In our last class we began talking about animal domestication.
And we said it's the process whereby a population of animals is bred in captivity and becomes accustomed to being provided for and controlled by humans.
Question, Jim?
Yeah. I was thinking...you said domesticated animals usually served some kind of purpose for humans, like horses could...uh...pull heavy loads,
and dogs could hunt or herd sheep, but cats, why were they ever domesticated?
I mean, mine can't do much of anything.
Interesting question. Cats don't seem likely candidates for domestication, do they?
They actually lack an important characteristic that most animals that can be domesticated have.
Domesticable animals tend to live in herds or packs, with clear dominance hierarchies.
Humans could easily take advantage of this hierarchical structure.
By supplanting the alpha individual, they could gain control of the whole group or of individuals as in the case of dogs.
Cats in the wild, though, rarely have this structure. For the most part, they are solitary hunters.
But as for their utility to humans, well, it's helpful to think about when and where cat domestication might have begun.
Any ideas, Jim?
Well, I guess ancient Egypt.
I’m thinking of all those ancient Egyptian paintings of cats.
Good guess.
Those paintings you mentioned do provide the oldest known depictions of full cat domestication, where cats are, without question, household companions.
The paintings from about 3,600 years ago typically show cats in Egyptian homes poised under chairs, sometimes wearing collars, eating scraps of food out of bowls.
But the Egyptians don't get credited for the early stages of cat domestication where cats are just beginning to interact with humans.
There are signs of early domestication as far back as 9,500 years ago!
Recently, two graves were discovered on the Island of Cyprus.
One was the grave of a human, buried with some tools, sea shells and other items, and nearby, a cat was buried in its own grave.
Interestingly, the cat's body was oriented in the same westward direction as the human's body.
Another notable thing about the two bodies was that they were in an identical state of preservation, suggesting they had been buried at the same time.
So we can assume that humans had at least some kind of relationship with cats as early as 9,500 years ago!
So cat domestication began in Cyprus?
Well, except cats weren't native to Cyprus.
They were undoubtedly brought over to the island by boat probably from the nearby coast of the Fertile Crescent in the Middle East.
In fact, extensive DNA analysis has now confirmed what archaeologists have believed for quite some time.
All modern domesticate cats arose from just one subspecies of wild cat from that single location: the Fertile Crescent, and not from any of the other four subspecies of wild cats located in other areas throughout the world.
Pretty amazing, isn't it?
Which brings us back to Jim's question: Why did it happen and how?
Well, for years, researchers have pondered this question of cat domestication, and the best I can do here is just a theory, but tell me it doesn't make sense.
In evolutionary terms, early settlements and agriculture in the Fertile Crescent around 10,000 years ago created a completely new environment for any wild animals that were flexible and curious enough to exploit it.
Mice were attracted to these settlements, and cats, being obligate carnivores they must eat meat to thrive，They were almost certainly drawn to the settlements by the mice.
Over time, only the cats that could adapt to living in human-dominated environments would have stayed and thrived.
People probably encouraged them to stick around and controlled the mice in the field and the granaries, and eventually, their homes, and perhaps simply grew to like their company too.
Hmm...so in a way, the difference with cats was that domestication was their idea instead of ours.
But why do you suppose only one of the five subspecies was domesticated?
Were the others just not friendly enough towards humans?
Well, no. In fact, at least two of the other subspecies are known to be relatively friendly, but the Fertile Crescent subspecies had, well, a head start because of its proximity to the first human settlements.
And as agriculture spread, the tamed ancestors of this subspecies spread with it.
So they fill the niche of home companion in each region they entered and effectively shut out the local subspecies that were already there. "
L37C2
"Narrator:Listen to a conversation between a student and a university theater manager.Student: I'm sorry if my email wasn't clear. It's probably best that we are meeting now. I have a lot of questions.
So do I. But first let me say that I’m so glad that this tradition is continuing.
I guess for the last twenty years now, every senior classes put on a Shakespeare Play.
Student: It won't be anything like the drama department's productions in the main theater, but we are really excited.
We are doing ""As You Like It"" this year.
Manager: Great! Let's start with the timing. You want the production to run on two consecutive nights, Thursday and Friday?
Student: Right. The end of April will be best. Maybe the last Thursday and Friday? We are flexible with the dates.
Manager: The only bookings at the small theater are some recitals in the beginning of the month, so I’ll make sure to get it on the calendar.
But you other questions...let's see. You want to use fire on stage?
Student: Well, our idea is to reproduce the conditions of an Elizabethan playhouse, make it as authentic as possible.
And of course, they didn't have electric lights 500 years ago. So we thought if we had candles, a lot of candles actually...
Manager: To light the stage?
Student: Yeah.
Manager: Okay. Um...you'd need a special permit. You could get one from the city council.
But for one thing, it's difficult and time-consuming to get permission and expensive.
And it's not just a permit, you’ll have to pay for an inspection and to have a fire marshal present at the shows.
Student: That does sound expensive. If we had a budget like the drama department...but it looks like we'll have to scale back a bit.
Manager: Are you charging admission?
Student: There will be a small admission fee. In Shakespeare's time, if you paid a little more, you got a more comfortable seat.
I don't see how we could do that though. I mean, all the seats are the same, right?
Manager: Right. I guess you could charge more for the seats upfront, but it's a small theater.
Student: And there isn't much difference between the front and the back.
Manager: Anyway, for lighting, you could buy those electric lanterns that are made to look as if they had a natural flame.
Student: If that's the best we can do, not exactly authentic, though.
Manager: But safer and less expensive. And about the food...
Student: Selling food was also done in Shakespeare's time. It's related to the candles actually.
When the candles burn down, they stops the play so they can bring out new ones, and that's when they sold snacks.
That's how the custom of having an intermission started.
Manager: I always thought intermissions began as a way to change the scenery.
Student: Oh, speaking of scenery...do you have the exact dimensions of the stage?
Manager: Sure. "
L37L3
"Listen to part of a lecture in an art history class.I'm sure you've all heard of the Mona Lisa, the famous painting by Leonardo Da Vinci.
The Mona Lisa is a portrait of a woman and it's thought to be the portrait of Lisa Gherardini but that's not certain.
In fact, many things about the Mona Lisa remain a mystery.
For example, we don't know exactly who commissioned the painting or how long Da Vinci worked on it and there are actually many scholars who think the mystery makes the painting more interesting.
I think it places unfortunate limits on our analyses, makes it hard to make strong arguments about the painting.
Anyway, getting to the point: most people today might have never heard of the Mona Lisa, or of many other now famous works of art for that matter,
if it hadn't been for Giorgio Vasari.
Giorgio Vasari was an Italian painter, architect and scholar.
In the mid fifteen hundreds, he wrote a book called Lives of the Most Eminent Painters, Sculptors and Architects in which he describes, among many other things, the features of the Mona Lisa, including her famous smile.
This book drew a lot of attention to Da Vinci and significantly increased the Mona Lisa's fame.
As the title suggests, Lives of the Most Eminent Painters, Sculptors and Architects includes biographies not only of Da Vinci but also of many other now famous Italian renaissance artists.
This was the first time that a European author had made the personal lives of the artists a central component of an art history book and many a later author followed the example.
The more important the artist in Vasari's view, the longer their biography in the book.
And by far, the longest of the biographies, is that of Michelangelo, the painter of the Sistine Chapel ceiling and sculptor of the famous statue of David,
whose work Vasari adopted as his benchmark, his reference point for evaluating everyone else's artwork.
Many of the biographies are extremely detailed with all the basic facts about where the artists were born,
where they'd worked, who their teachers were and so on.
But I read Vasari's book cover to cover almost every summer.
I find it a great way to unwind during the summer break and what keeps me coming back to it are the anecdotes, fascinating anecdotes, that give you glimpses in the artist's private lives,
their dreams, their fears, their virtues, their vices.
In his book, Vasari also tackled, quite successfully I might add, the enormous task of sorting out which works had been done by which artists, which works belong in the same stylistic categories, which works belong in similar categories in terms of quality and so on, stuff you take for granted today.
But again, Vasari was the first European author to do that.
A word of caution though: Vasari was not at all averse to, how should I put it, modifying the facts.
For example, in his book, he has a touching description of Da Vinci's death, in which Da Vinci dies in the arms of his last patron:
The king of France, Francis the First.
Now, Da Vinci did spend the last years of his life working in the court of Francis the First.
Vasari seemed to have overlooked a minor detail, however, the well documented fact that the king was far away when Da Vinci breathed his last breath.
But why let the fact stand in the way of a great story, right?
Since Vasari's tales are, as I've said, so compelling and because they have been repeated by so many subsequent authors, they're still often taken at face value. Even today. No questions asked "
L37L4
"Listen to part of a lecture in a biology class.So, to review, who remembers how animals are classified in terms of body temperature? Mike?
Um, endotherms and ectotherms?
Right! All animals are considered either endotherms or ectotherms.
Therm-that means heat, and the main thing that distinguishes endotherms from ectotherms is the source of body heat.
So an endotherm, endo- meaning internal, an endotherm's body heat mainly comes from inside its body.
It can generate its own heat internally with its metabolism.
And an ectotherm, ecto- meaning external, an ectotherm gets its body heat mainly from outside its own body, meaning from its environment, mostly from the sun's radiation.
So we've got endotherms. Mammals and birds are the classes that fall under this category.
And ectotherms, that's pretty much everything else, including reptiles, amphibians, insects.
Now, body temperature is important.
And if an animal’s environment gets very hot or very cold, something needs to happen in order for the animal to maintain its body temperature within its normal range.
In endotherms, this is mostly physiological. The body changes its rate of heat production.
Okay, well, humans are endotherms. What does your body automatically do when it gets really cold?
Shiver?
Right, shivering. In fact, any muscle movement increases metabolism, the process that produces heat and keeps your body temperature up when your surroundings get cold.
And then there's what's known as brown fat, like other kinds of fat, it stores triiodothyronine,
but brown fat is unique because it chemically produces lots of heat even without muscle movement.
That's especially beneficial for small mammals in colder climates.
And when an animal gets too hot, well, have you ever seen a dog cooling off by taking short, quick breaths?
And humans, we sweat, of course, perspire, which also gets rid of body heat.
These are automatic, physiological responses too. Yes, Sally?
So, in endotherms it's really not about behavior, about doing things.
Well, a human, you know, might put on a winter coat or jump in a swimming pool, or elephants, elephants might splash themselves with cold water when it's warm out, but for the most part, no.
It's not what we endotherms do that keeps our temperatures within range, unlike ectotherms.
Well, what about ectotherms, like frogs? They must have metabolism too.
Sure they do.
It's just that metabolism in ectotherms is so much lower.
I mean, the metabolic rate of an endotherm, say, a mouse, is at least six or seven times that of an ectotherm of a similar size like a frog or a lizard.
An ectotherm doesn't generate nearly as much heat internally.
So its body temperature will tend to equalize with the temperature of its surroundings.
And that's where behavior comes in. Imagine a lizard, okay, living in the desert.
Now, a desert gets very cold at night and very hot during the day.
So what does the lizard do to maintain its body temperature?
Well, on a cold morning, it can warm itself by going to a sunny spot and lying in the sun, and later if it gets too hot, it can seek out a cool place in the shade.
It's by means of such behavior that an ectotherm like this lizard regulates its temperature.
But you put that same lizard in a temperature controlled chamber and gradually drop the temperature, say, 20 degrees, and here of course, the lizard can't go off to lie in the sun.
So what happens?
Well, the lizard's body temperature drops too.
Right, and this really slows down its metabolism, which depends on temperature.
Even that 20 degrees drop in body temperature though, the lizard can survive that no problem, and come out just fine when it warms up again.
Ectotherms can do that.
But an ectotherm probably wouldn't survive in a place where the temperatures got too low, right?
Professor: Ever heard a frog being chased by a polar bear?
No.
Well, there you are. Now a mouse in the same situation, in the same temperature chamber, is just the opposite of the lizard.
When the temperature goes down, the mouse's metabolism goes up. "
L38C1
"Narrator: Listen to a conversation between a student and an employee in the university housing office.Employee: Hi. Can I help you?
Student: I hope so. I am taking a class this summer and I need to see about getting campus housing.
Employee: Oh, sorry. I am afraid the deadline to apply for summer housing in the dormitories has already passed.
I could help you look for something off campus.
Student: Well, see, I only found out yesterday I need to take this course.
It wasn't really my idea.
I mean I was gonna take it in the fall.
It is a course I need for my major in cognitive science, Professor Wilson was supposed to teach it but now...
Employee: Oh, right. I heard he is taking a last-minute leave of absence next year.
I hope everything is okay.
Student: Oh yeah. He'll be in Botswana helping develop the new cognitive science program at our sister university there.
Anyway I have to take the course this summer if I want to graduate on time.
I’ve got a note from the dean approving the whole situation.
Employee: Oh, well, in that case I guess we'd better make an exception for you.
Only problem is most of the bedrooms are gone already.
Was there any particular dorm you were interested in?
Student: Well, I’m in Randolph Hall right now, but my roommate's graduating in May so I have signed up for a single in Murphy for the fall, room 206.
I was hoping I might be able to just move in there now.
Employee: Well, let's see what the computer says.
Sorry, that room's scheduled for repainting and maintenance over the summer.
So I can't give it to you.
Student: I don't really care if it's repainted.
I’ll be covering most of the walls with posters anyway.
Couldn't I just take it as is?
Employee: Sorry, no. It is actually a city ordinance.
All rental rooms including dorm rooms have to be painted at least once every five years.
Student: Oh, well, how about if I stay where I’m for the summer?
I’m pretty sure they just painted it a couple years ago.
Employee: Hang on, let me check. You said Randolph, right?
Student: Room 122.
Employee: Oops. Afraid not. The entire floor is taken.
Student: Oh, well. Guess I’ll just have to move twice.
Employee: One sec. I have got one more idea.
Here we go. There is a room open in Murphy just down the hall from your new one.
That way come fall, you'd only have to carry your things a few doors down.
Student: Okay, works for me.
Employee: Now, that room is a double.
Right now you have got it to yourself but there's a chance someone else might sign up at the last minute, not likely.
But you could end up with a roommate for the summer. Would that be okay?
Student: Oh, sure. I can get along with anyone for a couple of months.
Employee: Okay, then, I will get the forms printed up.
They should be ready for you by tomorrow afternoon.
You can stop by and sign them then.
Student: Excellent, thanks. "
L38L1
"Narrator: Listen to part of a lecture in a botany class.Professor: Okay. Let's move on, to bacteria and viruses that can infect plants.
And let's start out with a virus that's rather common in various plants but first became known in connection with tulips.
This virus can cause a change in pigmentation that dramatically affects the color of the plant's leaves or flower petals.
But since not all cells of the plant tissue are infected, the result tends to be color variation.
With color intensified in one part of the flower petal and faded in another, this is called color breaking.
And the virus that causes this in tulip is called the tulip-breaking virus.
The tulip-breaking virus is now known to have detrimental effects on plants.
They're weaker and sometimes reduced in size.
But for centuries people didn't have a clue about this virus.
Not until the early 1900s was it known what caused the color breaking in tulips,
what made the tulip plant produce flower petals so radically different in color or in pattern from what you would have expected.
Tulip flowers with stripes or streaks or feather or flame patterns on their petals,
there is no doubt in my mind that these symptoms of this breaking virus affected human behavior too indirectly,
that they set off the famous tulip craze in the Netherlands.
Let me explain.
In the 17th century, the Netherlands was among the most important trading centers in all of Europe with lots of rich merchants who wanted to showcase their wealth,
for example, by displaying exotic tulips in their private gardens.
Now, tulips are not native to the Netherlands.
They originated in the mountains of Central Asia and spread from Persia, present-day Iran, to the Turkish Ottoman Empire and from there eventually reached Europe.
There's an explanation for the origin of the name ""tulip"" that kind of reflects this.
Apparently, it came from a Persian word for ""turban"", you know, a cloth wound round the head.
Um, a style of headgear worn by men in that part of the world.
Well, the Ottomans used a similar name for tulips after they acquired them from Persia.
And then, in the late 16th century, a variation on that name found its way from what is now Turkey to the Netherlands along with the plant itself.
Okay.
A tulip, of course, is typically grown from an underground bulb.
And although as it flowers the old bulb shrivels to almost nothing,
the plant produces another large bulb and maybe two, three, four smaller ones to take its place,
and while tulips take up to seven years to bloom if you start from seeds.
A large bulb can produce a flower the very next year.
With the smaller bulbs it takes maybe a couple of years.
And since these bulbs remain viable for quite a long time, even out of the ground, they can be stored or transported long distances without much of a problem,
which helps explain the spread of tulip cultivation.
At first, tulips were rare in the Netherlands and only for the wealthy.
But in the early 17th century, as more bulbs were produced there, you'd think the prices would come down.
In fact, though, the popularity of some tulips increased tremendously.
So demands soon far exceeded supply and their prices skyrocketed.
And the tulips most prized for their uniqueness and beauty were apparently the ones infected by this mysterious virus.
At that time, nobody was really able to breed tulips like these.
Color breaking happened in just two or three out of a hundred bulbs and seemingly just by chance.
And since you didn't really know when you bought a bulb if the colors would break, well, Dutch speculators invested hand over fist and drove prices sky high.
Some bulbs, even while still in the ground, were sold for as much as you would pay for a house at the time.
But the huge speculative bubble created by this tulip craze eventually collapsed.
And when the prices fell, that wiped out a lot of fortunes almost overnight.
Later on, tulip breeders learned to duplicate color breaking in healthy, uninfected plants,
so the spectacular-looking tulips so common today are the result not of chance viral infections, but of carefully controlled breeding. "
L38L2
"Narrator: Listen to part of a lecture in a business class.Professor: Last time we talked about the design and production of advertisements.
Today we'll be discussing how advertisers decide where to display their ads.
This is critical to a successful marketing campaign because it builds up the consumer's brand awareness, their knowledge of a product made by a particular manufacturer.
And studies show that the more you are aware of a product, there's a greater chance you'll buy it.
Now, most ads we see in the media, like in newspapers, television, or magazines, are placed where the product is matched with a medium of a similar theme.
Let's take...uh...the medium of magazines as an example. If you were to flip through, say, an automotive magazine, what kind of ads would you expect to find? Jack?
Student: Ads for cars, car parts, tires, stuff like that.
Professor: Good. When you have an ad for a certain product in media with a similar theme, we call that congruent media.
Congruent simply means it fits. It's what you would expect. Congruent media placement is the most logical choice for marketing a product.
First, it's obvious that people reading a car magazine are interested in cars.
So if you place a car ad there, you know you are reaching the right audience.
Also, research shows that when people read an ad in a congruent medium, afterwards, they have pretty good recall of what was advertised.
Now, there's another approach, that's placing ads in incongruent media.
Incongruent media are the magazines, newspapers, TV spots, where the theme doesn't match the theme of the product.
Even though it seems counterintuitive, research shows that this also is an effective marketing strategy.
One study tested this by placing car advertisements in a magazine that had an incongruent theme and it found that this contributed to consumers' positive attitudes toward the ad and the car being advertised.
Student: What kind of magazine was it?
Professor: A cooking magazine.
Student: Wow! That worked? I'd have imagined it would be a distraction to see something like that, you know, out of place.
Professor: Well, keep in mind that potential car buyers don't read only car magazines.
Most have other interests.
Many of them probably subscribe to other magazines, a news weekly, a financial publication, something related to a special interest or hobby.
So what marketers have to do then is carefully research potential customers and look for overlapping interests, which magazine overlaps most with the interests of the car buyer.
Then when they do choose to place ads in incongruent media, they know they'll be effective.
Student: Okay.
Professor: Now this study suggests that because the people reading a cooking magazine didn't expect to see a car ad, they actually paid more attention.
And so for example, when people who like reading about cars see a car ad in a car magazine, they might pass over it quickly, while here...
Student: They actually took more time to read the ad.
Professor: Right! People paid more attention.
They processed the information more carefully when it appears in a medium with a different theme.
This ultimately results in stronger brand awareness, which leads to a more favorable impression of that product overall. Jenny?
Student: So according to the study, basically when I see an ad in an unexpected place, it'll make me want to buy the product?
Professor: Well, yes and no. The research shows you'll probably remember that ad and you are more likely to feel positive about that product.
Now, whether you'll go out to buy it is a different story.
Of course, there are other factors at work here.
You remember those criteria we discussed last week?
Anyway, this explains why most marketers today rely on a mix of congruent and incongruent media.
But there are limits to how incongruent the media should be.
You don't want a totally mismatch.
So in a magazine aimed at new parents, you often see car advertisements since parents buy and drive cars.
But there are different types of cars, right?
For example, placing an ad here for a big roomie van, which is popular with big families would make sense, but a snappy sports car with only two seats?
Well, that would clearly be too much of a mismatch. "
L38C2
"Narrator: Listen to a conversation between a student and his ecology professor.Professor: How is it going? Tom.
Student: Great! I was, oh. I wanted to tell you.
You know the guest speaker you brought into class last week from the wildlife conservation center.
Professor: Susan Brown. Yes.
She is an old friend from graduate school.
Student: Her talk on wildlife population modeling, well, it was very theoretical.
Professor: It was certainly a change of pace from what we usually do.
Student: Yeah, but I think I pretty much followed along.
Plus, I like to see people get so passionate about ecology.
Professor: Oh, right. Ecology is your major field of study, isn't it?
Yes, Susan Brown's certainly a lively speaker.
What a shame she didn't go into teaching.
Student: Uh, anyway, what I, well, a while ago, I saw this blurb in the school paper about an exchange program that's part of the study abroad office.
And today there was booth set up in the student center with a couple of students answering questions about the university's programs in foreign countries.
Seeing the booth reminded me about the article in the paper and...
Professor: Thinking about going abroad in the coming year?
Student: Actually I just spent last summer studying in Tokyo.
I think that satisfied my urge to travel.
Professor: It must've been quite an experience.
Student: Definitely. Taking all those language courses was really challenging.
But what I wanted to find out at the booth was:
it’s...um...a domestic exchange program, not studying abroad, but studying for a year somewhere else here in the United States.
Professor: I don't think I have heard of that.
Student: Well, neither had the guys in the booth.
They didn't know what I was talking about.
But when I talked to the supervisor in the study abroad office, it turns out we are part of a...
a group of universities throughout the US that does a domestic exchange program.
Professor: Huh! So you spent...what...a year at another university and your classes count toward your degree here?
Student: Yeah, and I paid the same fees, tuition, room and board, that I pay here.
So it doesn't really cost any extra.
Professor: Interesting.
Student: And you know I’ve lived here in southern Florida my whole life.
And I’ve always been interested in Montana.
The university in Montana, where I want to go, has classes that deal specifically with the ecology there.
Like I am interested in the greater yellow stone ecosystem.
It is such an important ecosystem being the source of three major rivers, and I want to learn more about it.
Professor: Wow! This is a unique idea.
The climate, the plants and wildlife, it's really different from here, probably the culture too in a way,
and don't forget about all the outdoor activities you could do there, hiking, skiing, and the national parks.
Student: That's true. Anyway I’ll have to get my application together in the next month or so,
and I’ll need two letters of recommendation, one from a professor in my major department.
Professor: Consider it done.
Student: Thanks. "
L38L3
"Narrator: Listen to part of a lecture in a music history class.Professor: So let's continue our discussion of twentieth century music.
By the early twentieth century, some composers in Europe and the United States, composers of what's considered classical music, were already moving away from traditional forms and were experimenting with different ways of composing.
In many cases, moving away from traditional western scales and tonalities.
But as the century progressed, some composers, composers of what was called avant-garde music, went further.
Their experiments with musical composition were not always well accepted.
Quite the contrary, you see, many people felt avant-garde music was too radical and wasn't even legitimate art.
A case in point is the composer John Cage.
Cage was probably the most famous composer of twentieth-century avant-garde music.
He didn't begin his music radical, but as time went on, his musical experiments led him there.
What caused the change?
Two experiences in particular entirely changed how he thought about music.
First was his 1951 meeting with the avant-garde painter Robert Rauschenberg.
Now, avant-garde is a term that applies many different artistic genres.
Rauschenberg had created a series of famous paintings that consisted simply of white paint of different textures on canvas.
That's all they were: white.
But the concept of these paintings actually wasn't so simple.
Rauschenberg was asking, in effect, how much could you leave out of an artwork and still have something?
Because in fact, even on a purely white canvas, there's still plenty to see, shadows, dust, reflections.
For Cage, Rauschenberg's white paintings opened up a whole new way of understanding what art could be.
The second key experience in Cage's development came when he stepped in an anechoic chamber.
An anechoic chamber is a room with special walls that absorb sound.
Anechoic means without echoes.
So an anechoic chamber was a room where, in theory, you can experience total silence.
But Cage entered this room and he heard two sounds, one high and one low.
The high sound, he was told, was his nervous system operating, and the low sound was his blood circulating.
Cage was profoundly affected. He realized that music doesn't need to be created intentionally. We find it all around us.
This idea came to be called found sound.
It's the sounds that are already there, traffic outside your window, or whatever.
For Cage, they were just as musical as sounds made by musical instruments.
These experiences led Cage to create a composition that would convey the idea of found sound.
That is, it would provide an opportunity for the audience to identify random sounds of the environment as music.
So he composed a piece called 4 minutes 33 seconds, commonly known as the silent composition.
And this composition was completely silent, literally.
When it was performed the first time, a pianist sat on stage at the piano and the only thing he did was raise and lower the lid of the keyboard to indicate the beginning or ending of a movement.
4 minutes 33 seconds had three movements, but not a note was played in any of them.
Well, the audience was outraged.
Music critics called the piece ridiculous.
But Cage saw no reason for the outrage.
The fact that the audience was scandalized showed that they missed the whole point of his composition, which was that there's no such thing as silence, no such thing as a complete absence of sound, and whilst in fact during that first performance, the sound of wind and rain and people muttering.
Cage had a different understanding of silence.
He defined silence as the absence of intended sounds.
So to perceive 4 minutes 33 seconds as music, the audience needed to tune in to the sounds around them.
This was quite revolutionary. So we should probably be sympathetic to their reactions at the time. I mean, it’s confounding people even today!
Cage's silent composition is still performed all over the world, but I’m afraid to say, it's often misinterpreted.
It's been choreographed, in dance performances for instance, in which case the sound was the beat of the dancers' feet against the stage floor.
And it's been performed by people who made noises on purpose to call attention to the piece's silence.
Can you see why we can consider these performances to be misinterpretations? "
L38L4
"Narrator: Listen to part of a lecture in an astronomy class.Professor: Last week we discussed the formation of Earth and the other rocky planets, of planets in the inner solar system.
Uh, so, what about the gas giants? Jupiter, Saturn, Uranus, and Neptune.
Well, there's two theories.
But first, let's recap.
We believe our solar system began as a huge spinning cloud of dust and gas, which flattened and eventually collapsed in on itself.
The matter it's centered condensed into a ball of hot gas and dust, eventually becoming our sun.
And what happened to the remaining cloud?To the disk encircling the sun when it was a young star?
Student: The rocky planets were born. Um, dust, little grains of rock and metal within the disk collided with each other and stuck together, and this process sort of snowballed over millions of years until the chunks grew into mini-planets, proto-planets.
Professor: Yeah. This process is called accretion.
And we call the disk an accretion disk.
Now, think of it as two parts: an inner accretion disk, and an outer accretion disk.
In the inner part, once an object gets large enough, that object's gravitational field gets stronger, which speeds up the accretion process.
You know, larger objects attract smaller ones and sort of gobble them up.
And eventually, you get a full-sized planet in its own orbit.
Okay. That's how the inner rocky planets probably formed by accretion.
But what about those gas planets in the outer solar system, in the outer accretion disk?
Well, the first theory says the accretion process was similar to the one that formed the rocky planets, with some key differences.
Remember, the gas giants are farther from the sun, where temperatures are much colder.
So, in the outer accretion disk, compounds like water and ammonia exist in frozen form.
Closer to the sun, they're more likely to be vaporized by solar radiation.
What this means is that in addition to rocky and metallic particles there would be other solids like frozen water and frozen ammonia.
Student: So more solid substances are available to clump into protoplanets, right?
Professor: Precisely! So the solid cores of the gas giants could conceivably have formed by accretion.
And once their mass reaches a certain point, around about 5 to 10 Earths, what would happen?
Student: 5 to 10 Earths...uh, with a mass that big, I guess gravity would start to pull in more and more material faster, right?
Professor: Material, meaning gas.
It would rapidly pull in more and more gas from the accretion disk, so you end up with a solid core of rock, metal and ice surrounded by massive amounts of gas.
That's the core accretion theory. Now, the other theory is called the disk instability theory.
The disk instability theory holds that gas begins the planet-making process, without a solid core.
You see, most of the outer accretion disk would have been gas.
We believe solid particles probably made up just one percent of the outer accretion disk.
So this theory suggests that large planets, the gas giants, uh, they develop from large clumps of mostly gas and some dust in an accretion disk.
Outer regions of an accretion disk can be unstable, gravitationally unstable, which is what causes these clumps to form, and in some cases, grow in to proto- planets.
Over time, dust particles within a gas clump coalesce, bond together, and eventually fall toward the center, creating a core.
Once this happens, the gas clump grows relatively quickly as its gravity pulls in more and more gas and dust particles.
And this whole process can theoretically happen within one hundred thousand years. "
L39C1
"Narrator: Listen to a conversation between a student and a theater professor.Student: Hi, Professor Johns.
Professor: Hey, didn't I see you at the performance of Crimes of the Heart last night?
Student: Yeah. Actually my roommate had a small part in it.
Professor: Really? I was impressed with the performance.
There sure are some talented people here.
What did you think?You know, Beth Henley is an okay playwright.
She has written some decent stuff, but it was a little too traditional, a little too ordinary, especially considering the research I'm doing.
Professor: Oh, what's that?
Student: On the Polish theater director Jerzy Grotowski.
Professor: Grotowski. Yeah, that's a little out of the mainstream.
Pretty experimental.
Student: That's what I wanted to talk to you about.
I had a question about our essay and presentation.
Professor: Okay.
Student: Yeah. Some of these ideas, uh, Grotowski's ideas are really hard to understand.
They are very abstract, philosophical.
And, well, I thought the class would get more out of it if I acted out some of it to demonstrate.
Professor: Interesting idea.
And what happens to the essay?
Student: Well, I will do the best I can with that, but supplement it with a performance.
You know, bring it to life.
Professor: Alright. But what exactly are we talking about here?
Grotowski, as I’m sure you know, had several phases in his career.
Student: I'm mainly interested in his idea from the late 1960's: poor theater.
You know, a reaction against a lot of props, light, fancy costumes, and all that.
So it would be good for the classroom.
I wouldn't need anything special.
Professor: Yes. I'm sure a lot of your classmates are unfamiliar with Grotowski.
This would be good for them.
Student: Right. And this leads...I think there's overlap between his poor theater phase and another phase of his, when he was concerned with the relationship between performers and the audience.
I also want to read more and write about that.
Professor: You know, I saw a performance several years ago.
It really threw me for a loop.
You know, you are used to just watching a play, sitting back, but this performance, borrowing Grotowski's principles, was really confrontational, a little uncomfortable.
The actors looked right in our eyes, even moved us around, involved us in the action.
Student: Yeah. I hope I can do the same when I perform for the class.
I’m a bit worried since the acting is so physical.
That there's so much physical preparation involved.
Professor: Well, some actors spend their whole lives working on this, so don't expect to get very far in a few weeks, but I'm sure you can bring a couple of points across.
And if you need some extra class time, let me know.
Student: No. I think I can fit it into the regular time for the presentation.
Professor: Okay. I think this will provide for some good discussion about these ideas and other aspects of the audience and their relationship to theatrical productions. "
L39L1
"Narrator: Listen to part of the lecture in a geology class.Professor: Since Earth formed some four and a half billion years ago, the number of minerals here has increased dramatically, from a few dozen relatively simple minerals early on to over 4,300 kinds of minerals we can identify today, many of them wonderfully complex.
A basic question of geology is how all these new minerals came into being.
Well, recent studies have turned to biology to try to explain how this happens.
Now, much of biology is studied through the lens of evolution.
And the theory of evolution suggests that as environments change, and inevitably they do, some organisms will have characteristics that allow them to adapt to those changes successfully, characteristics that help these organisms develop and survive, and reproduce.
And when environments become more complex, as tends to happen over time, those earlier adaptations, those variations, become the basis of yet other combinations and variations, and lead to ever more diverse and complex forms of life.
So from fewer, simpler and relatively similar forms of life billions of years ago, life on Earth has now become a dazzling array of diversity and complexity.
Well, some geologists now want to apply this concept to explain mineral diversity too.
The conditions that minerals are under are not constant, conditions like temperature, or pressure, or chemical surroundings.
These change, often in cycles, increasing and decreasing slowly over time.
And as conditions change, minerals sometimes break down.
And their atoms recombine into totally new compounds as part of a process some called mineral evolution.
Now, minerals are not alive of course, so this is not evolution in quite the same sense you'd have in living organisms, but there do appear to be some parallels.
Living organisms not only adapt to their environment, but also affect it, change the environment within which other organisms may then develop.
Likewise each new mineral also enriches the chemical environment from which lots of other even more complex new minerals may be formed in the future.
Beyond these similarities though, what's really fascinating about mineral evolution is the way minerals apparently coevolve with living organisms.
Uh, what do I mean by that?
Well, it's maybe a billion years after Earth's formation that we first see evidence of life.
Of course early life forms were primitive, just tiny, single-celled microbes, but overtime, they had a profound effect.
Huge numbers of these microbes began producing food by photosynthesis, which of course also freed up enormous amounts of oxygen and lots of that oxygen interacted with the atoms of existing minerals, creating rust out of iron for instance, reacting with a whole range of different metals to create lots of new minerals.
Now, living organisms rely on minerals, but they not only take in some minerals as nutrients, they also excrete others as waste products, including what we call bio minerals, minerals that form with the help of biological life.
We can see geologic evidence of bio mineral production in what are called stromatolites.
Stromatolites look like wavy layers of sedimentary rock, but they are really fossils, fossils of the waste from microbial masts.
Microbial masts are vast colonies of one-celled organisms that were once the most prevalent form of life on Earth.
And the study of stromatolites indicates that these ancient microbial masts interacted with minerals in the environment and left behind new compounds as waste products.
Bio minerals like carbonates, phosphates, and silica.
In fact, we've grown microbial masts in the laboratory.
And over time, they too have produced some of the same sorts of minerals found in stromatolites.
Uh, you don't need to know the details of the process right now.
We are still figuring out just how it works ourselves.
But you might be interested to know that this concept of mineral evolution is being used in the search for evidence of life on other planets.
The thinking is that if certain minerals occur here on Earth, as a result of a biological process, and if we also find those same minerals on another planet, this would suggest that life may have once existed there!
But just because a particular mineral is found on, say Mars or Venus, we really shouldn't assume that whatever caused it to turn up there, must be the same process that formed that mineral here on Earth. "
L39L2
"Narrator: Listen to part of a lecture in an anthropology class.The professor is discussing ethnography.
Professor: Since ethnography is all about the descriptive study of an individual culture, film has proved to have great value as a tool for anthropologists in their research.
Let's look at a particularly effective approach to ethnographic film-making, which was developed in the 1970s.
This particular style of ethnographic filmmaking is called the community-determined approach.
The intent of the community-determined approach is to achieve a kind of, uh... shared authorship.
See... in this approach, the goals of the project and how the information will be used are discussed ahead of time, and so a culture, uh... community is not just the focus of the film.
They are actually equal participants in the whole ethnographic process.
In this way the film revolves around the actual values and concerns of the individuals in the community, and it honors an individual's ethical right to control how he or she is presented in the media.
Several of these films were made in Alaskan communities in the 1970's.
Student: So how does it work, you know, the community-determined part?
Professor: Well, it takes a lot of preparation.
First, way before filming begins, the filmmakers visit the community and meet with the village council who are the decision-makers of the community.
A film if available is shown to the village council so that they get an idea of the experience of another community.
After the meeting, the filmmakers leave and the village council is given all the time they need to think about what was discussed.
Later, if the village council members are interested, they send a letter or call.
Student: There's no follow-up meeting?
Professor: Not unless they want one.
See, this helps remove any pressure to say yes.
The social pressure from the filmmakers' presence.
Student: So, if they agree, then what?
Professor: Then the filmmakers start living in the community.
See, another major point in the community-determined approach... it's very important that the filmmakers plan to stay in the community for an extended period of time, not weeks, but months.
And really, there are several reasons for this.
Any ideas?
Student: The filmmakers could get a more realistic sense of the pace of life in that community?
Uh, its daily rhythm?
Professor: Correct, and it allows the filmmakers to shed some of their assumptions so that they better interpret what they see.
Student: I bet it also takes the mystery out of the filmmaking process.
You know, everyone has time to get used to the filmmakers and their equipment.
Professor: Exactly, trust is established and relationships are built first.
Student: Wow, this seems like a long process.
It must cost a fortune.
Professor: It does. Even with a small film crew any project as involved as this is bound to.
Student: OK, so who decides what goes into the film?
Professor: Well, such decisions are made by general consensus within the community.
So, for instance, the community, not the filmmakers, decide who is to be interviewed for the films.
Control of the interview is in the interviewee's hands.
If the person being interviewed says to stop at any time, the recording stops.
He or she states where they wish to be filmed and when and what topic they wish to speak about.
The community members review the footage both midway and at the end of the filming.
And if they want any scene deleted, it gets removed.
That's the level of respect and regard for the interviewee's preferences and those of the community in general.
Student: So then what language is everything filmed in?
Professor: Excellent question!
Language is culture, isn't it? So the native language, rather than a dubbed voiceover in the filmmakers language, is the primary language of the film.
This way a speaker's emotions and manner of expression really come through, even if we don't know their language.
Subtitles are placed in a secondary position at the bottom of the screen.
Student: And the subtitles probably give only the gist of what's actually being said.
Professor: Yeah, a word for word translation could become too complicated or it'd go by too fast on the screen. "
L39C2
"Narrator: Listen to a conversation between a student and an employee in the university career services center.Employee: Hi. Can I help you?
Student: One of my sociology professors suggested that I come to the career services center and talk to you.
She thought there was going to be a career fair soon where I could talk to different companies about a possible summer job.
Employee: Well, these are classroom-to-cooperation career fair.
That's our largest fair every year.
We get representatives from over 100 companies and they actually conduct interviews right here on campus.
Student: Great! What kinds of companies?
Employee: This year we'll have representatives from all the major technology companies in the area.
Student: Oh. Then I don't know how helpful that will be.
I'm a sociology major.
Employee: Well, that's fine.
Sociology students often get jobs in marketing, administration, human resources.
Tech companies have openings in those areas.
Student: Well, I’m mainly interested in working with people, in human services.
Employee: Well, in that case, we do have a smaller fair coming up, with smaller companies and some public service organizations.
This one might be a better fit for you.
Student: Yeah. I think that was the one my professor was talking about.
Employee: Most likely.
Now, have you been to a fair like this before?
Student: Not really, but I just show up and talk to different companies, right?
I don't have to register or anything, do I?
Employee: No, you don't have to register, but I highly recommend that you come prepared.
Student: Prepared?
Employee: You should dress professionally and have copies of your resume with you.
Student: Copies of my resume?
Do I really need that?
Employee: Well, it's not a requirement, but a lot of students come to our career fairs.
Plus, we've opened up these fairs to the public, to people in the neighboring communities.
So anything you can do to make yourself look more...well...look more professional.
That's gonna set you apart from the other job applicants.
Student: Um..I don't even have a resume.
I’ve never written one before.
Employee: Oh, that's not a problem at all.
Have you been to our new website?
It has all sorts of information about how to write a resume.
And once you've written it, you can make an appointment to bring it in to us at the career services center and have someone look at it with you.
Student: Okay. So I really need to have a resume just to get a summer job?
Employee: That depends on the company, but it's a good idea to have one.
Student: Okay. I guess I’ll need to have one sooner or later anyway.
Employee: Oh, and we'll be adding other information to our website eventually.
Like we'll have a list of the companies that are going to be at the career fair by the end of the week.
You should check it out and then maybe do some research on the companies.
That should help you when you talk to them too. "
L39L3
"Narrator: Listen to part of the lecture in a literature class.The professor is discussing Henry David Thoreau.
Professor: Nowadays, trains are pretty much taken for granted, but in the United States in the first part of the nineteenth century, when Thoreau lived, the railroad was a big deal, a technological revolution.
It was kind of earth-shattering to ride in a mechanical conveyance at fifty kilometers an hour in the 1830's.
The train, or ""iron horse"" as people called it, unlocked all sort of new experiences of time and space.
Thoreau himself praised trains for changing the way people experience their own bodies, for stirring the imagination in new ways.
So, in Thoreau's famous book, Walden, as you know, Walden is one of the central literary texts of the United States from that time period, and in it, Thoreau offers both praise and criticisms of trains.
Um. . .Thoreau is sometimes seen as being anti-modern, but he's not.
He uses poetic language, descriptive metaphors to inspire, to awe his readers, to communicate the fact that the railroad was a feat of human ingenuity.
Thoreau also associates trains with commerce and trade.
Though his attitudes toward commerce are complicated, he credits trains for delivering goods that feed and clothe society, things that improve human life.
But Thoreau also critiques trains on what we could call philosophical grounds.
He points out that riding on trains distorts people's experiences of the natural world.
Trees, wild life, landscapes just zip right past you and this is a real problem for him.
Thoreau also worries that trains had become an institution regulating the whole country.
He worries about people doing things in ""railroad fashion"", conforming to the train's timetable, letting their lives be governed by this mechanical device that is making its way into the fabric of society.
And he extends this critique to other inventions of the day, like the penny press, this very fast steam-driven press.
He talks about popular literary genres, like penny newspapers and dime novels, which were being published in mass quantities.
He worries about people no longer thinking for themselves and uncritically accepting all this cheap popular literature and the trivial details of the news.
So Thoreau is offering here a critique of technology that might be relevant for our own times, and I think it's important to take it seriously.
When there is a new invention, a new computer or a mobile phone technology, some new gadget,
there is a tendency to think that we need to have that thing, just as people were doing in the nineteenth century with respect to railroads.
Accepting them as a necessity without considering the possible negative consequences or trade-offs that can flow from them.
Okay. Can anybody offer an example of what I'm talking about? Deborah?
Student: Yeah, there was this new computer game that my brother just had to have, so he saved his money and bought it, which was good,
I guess that he saved his money and all, but now he spends like all his spare time playing that game instead of riding bikes with his friends or reading books like he used to do,
and it's causing some friction between him and our parents.
Professor: Perfect example! Deborah.
So this is one way to think about Thoreau's text, not just as an important book in its time, for what it tells us about the nineteenth century,
but also as a text that can teach us certain things about ourselves in contemporary society. "
L39L4
"Narrator: Listen to part of a lecture in a biology class.Professor: Your reading for today's class was about potential alternative sources of energy.
So one thing I want to do today is consider one of those potential energy sources: cellulose.
Who can tell us what cellulose is? Alan?
Student: Cellulose. Yeah. It's a tough organic molecule made of simple sugars.
It's found in the walls of all plant cells, in grass, trees, all plants.
And well, there's more cellulose than any other organic molecule on Earth.
Professor: Good. It's also a potential tremendous source of energy in part because there's so much of it.
Now, many organisms live on the energy they derive from consuming cellulose, like many species of bacteria or cows and goats.
Cows and goats have evolved highly specialized digestive systems that allow them to metabolize cellulose.
Student: But it's hard for most species to process cellulose?
Professor: Yes. And it's been very hard to develop a controlled way to process cellulose in a lab so that we can use the energy that's stored in it.
It needs to be converted into ethanol.
Let me explain.
Ethanol is a liquid, a kind of alcohol that's derived from processing sugars from plants, often corn.
And it can be used as fuel.
Many researchers believe it is the key to ending the reliance on gasoline.
The problem is that the amount of energy we get from corn-based ethanol isn't much more than the amount of energy that gets put into making it.
So it's not really worth it. Tina?
Student: But ethanol made from cellulose is different?
Professor: Yes. It's possible to get a vastly better energy yield on cellulose-based or cellulosic ethanol.
Student: Okay. So why don't we just use cellulosic ethanol?
Professor: Well, the problem is that the current method for processing cellulose into ethanol is very expensive and can't be done on a large scale.
See? Currently there are two key steps in the process.
The first is breaking the cellulose down into sugars.
This is done with an enzyme, a specific type of protein.
And second, after the enzyme has broken down the cellulose, yeast and other microorganisms, microbes are added to ferment those sugars into cellulosic ethanol.
Thing is, though, we are not too good at producing the enzymes that break down cellulose.
Those proteins are very difficult to make, to just assemble in a lab.
So usually we extract enzymes from microorganisms that produce them naturally.
Unfortunately, this is slow, expensive, and just not very efficient.
Student: So are they trying to develop a better way to make enzymes?
Professor: Actually there's a company that thinks they can do better than that.
It'd be more efficient and therefore cheaper to combine the two steps I mentioned into one.
That is, have a single organism that breaks down cellulose and then produces ethanol.
So what this company is doing is searching around the world and gathering naturally occurring microorganisms that do both things.
I mean, the best key to unlocking the power of cellulose may well lie in a rare species of bacteria or yeast in a jungle somewhere.
So researchers at this company have discovered some microorganisms that process cellulose and produce ethanol.
Now they are working on enhancing, improving certain natural characteristics of these microorganisms, manipulating them with sophisticated technology to make them work even more efficiently.
The goal, which seems to definitely be within reach, is to design an engineer, a superbug, a specific kind of microbe, that makes cheap, commercial production of cellulosic ethanol a really possibility. "
L40C1
"Listen to a conversation between a student and a business professor.Thanks for seeing me. Professor Jackson.
Sure, Tom. What can I do for you?
I'm gonna do my term project on service design.
What you see as a customer, the physical layout of the building, the parking lot.
And I thought I'd focus on various kinds of eateries: Restaurants, coffee shops, cafeterias
So I'd also analyze where you order your food, where you eat, and so on.
Wait. I thought you were gonna come up with a hypothetical business plan for an amusement park.
Isn't that what you e-mailed me last week?
I could've sworn...
Oh, I'm thinking of a Tom from another class. Tom Benson. Sorry. Sorry.
No problem. I did e-mail you my idea too though.
That's right. I remember now. Restaurants, Yeah.
So here's my question.
I read something about service standard that kind of confused me.
What's the difference between service design and service standard?
Service standard refers to what a company...
employees are ideally supposed to do in order for everything to operate smoothly.
The protocols to be followed.
Oh, okay.
So backing up.
Service design is...uh, think of the cafeteria here on campus.
There are several food counters, right?
All with big, clear signs to help you find what you're looking for: soups, salads, desserts.
So you know exactly where to go to get what you need.
And when you are finished picking up your food, where do you go?
To the cash registers.
And where are they?
Right before you get to the seating area.
Exactly. A place that you would logically move to next.
You know, not every place is like that.
This past weekend was my friend's birthday, and I went to a bakery in town to pick up a cake for her party.
And the layout of the place was weird.
People were all in each other's way, standing in the wrong lines to pay, to place orders.
Oh, and another thing, I heard this bakery makes really good apple pie, so I wanted to buy a slice of it too.
OK.
There was a little label that said apple pie where it's supposed to be but there wasn't any left.
That's what's called a service gap, maybe there wasn't enough training for the employees or maybe they just ran out pie that day.
But something is wrong with the process, and the service standard wasn't being met.
OK. I think I get it.
Anyway, since part of the requirements for the term project is to visit an actual place of business.
Do you think I could use our cafeteria?
They seem to have a lot of the things I'm looking for.
Well, campus businesses like the cafeteria or bookstore don't quite follow the kinds of service models we're studying in class.
You should go to some other local establishment I'd say.
I see.
But just call the manager ahead of time so they aren't surprised. "
L40L1
"Listen to part of a lecture in an art history class.Last class I passed out your assignment for your first paper and today I want to spend some time going over it.
Most people never take any art history until they get to college,
so many of you have probably never written an art history paper before.
I gave you a list of appropriate works of art for you to write about.
So your next step in this process needs to be to go look at the work you've selected as your topic and bring a pencil and a notepad with you.
Because I don't mean you should just drop by at the museum and glance at it, so you can say you've seen it in real life,
you need to go and sit in front of the work and really look at it carefully and slowly, and keep careful notes about what you see.
You'll need them for the kind of art history paper you are going to be writing.
It's what we call a formal analysis.
A formal analysis of a work of art, any kind of art,
is based on its formal qualities, which means qualities related to the form.
Things like color, texture, line, shapes, proportion and composition.
Now, probably the closest thing to a formal analysis you might have written is for an English class.
If, you've, say, written an analysis of a poem, you've used the same skills.
You've given an analysis of the poem by describing and analyzing its form and meter.
A formal analysis paper in art history is very similar.
Now, before you begin writing your formal analysis,
you'll want to start with a summary of the overall appearance of the work,
a brief description of what you see: either figures, people,
what are they doing, or is it a landscape,
or an abstract representation of something.
Tell what the subject is and what aspects are emphasized in the painting.
This will give your reader an overview of what the work looks like before you analyze it.
The next part of your paper, the actual formal analysis,
would be the longest and most important section of your paper,
where you describe and analyze individual design elements.
For this portion of the paper,
you are going to rely on the notes you took at the museum because you should be able to describe in detail the design elements the artist uses and how they are used.
For example, does the artist use harsh lines or soft lines?
Are the colors bright or muted? Focus on the design elements that you feel are most strongly represented in that particular work of art.
And if you don't know where to begin, take note of where your eye goes first.
Then describe things in the order in which your eye moves around the work.
This will help you understand how one part relates to another,
the interaction between the different parts of the work.
Ok? This kind of analysis should occur throughout the main portion of the paper.
In the last section of your paper,
and this goes beyond formal analysis,
you comment on the significance of what you've seen,
what details of the work convey meaning.
Some significant details will not be apparent to you right away.
But if you look long enough, you realize how important they are for your interpretation of the work.
Many years ago, I was writing a formal analysis of a painting of a little boy.
In the painting, a little boy was standing in his nursery and he was holding a toy bird in his hand.
And there were more toys around him in the background of the painting.
Because of the bird he was holding, I assumed at first that the painting was about the innocence of children.
But as I looked at the painting longer, I realized that the boy's eyes look sad even though there was no discernable expression on his face.
And then it dawned on me that even though he was surrounded by toys, he was all alone in his nursery.
The boy's eyes were a significant detail in the painting that I didn't notice at first. "
L40L2
"Listen to part of a lecture in an Environmental Conservation class.Next I want to talk about the collapse of the North American Cod population.
Let's look at Cape Cod in the northeastern United States.
the area was named Cape Cod because there was so many Cod fish in the waters just off its shores,
so many that the first Europeans who fished there in the 17th century reported it was better than in New Finland, Canada.
At that time, New Finland's Cod fishery was so rich that people said it was possible just to lower a bucket in the water,
pull it out and it would be full of cod,
but Cape Cod was even better,
so the fishing industry there did great until after the 1940s. Uh, there were simply too many fishing vessels,
sophisticated vessels, competing for fewer and fewer fish.
In the 1940s there were still about four hundred million pounds of fish caught at Cape Cod every year.
Just 50 years later though, by the 1990s,
commercial cod fishing there had become unprofitable.
The annual catch had gone down about 5% of its 1940s' level.
And here's what's so fascinating:
as more and more fishing vessels with better and better fishing technology were competing for cod,
this competition was causing changes to the biology of the fish and these changes were making it more and more difficult for the cod population to sustain itself.
Changes to the biology of the fish?
Well, if a cod fish could reproduce earlier than usual,
it'd have a better chance of passing on its genes to the next generation before being caught, right?
And sure enough, biologists noticed that around Cape Cod,
the cod were beginning to mature at an earlier age than normal.
Prior to the population collapse, cod usually took about 8 to 10 years to fully mature, to start to reproduce,
and they lived around 40 years total.
So cod had about 30 years of active reproductive life.
But now, cod were beginning to reproduce at a younger age, at 3 to 4 years old,
and they were living shorter lives because they were being caught,
so they had fewer years within which to reproduce.
Additionally, even though some fish in the population were maturing at an earlier age,
none was actually growing faster.
No cod has a way of speeding up its rate of growth.
So the younger reproductive age actually meant that smaller fish were reproducing.
And when you're a small cod reproducing,
you produce fewer eggs than a large cod.
The smaller cods simply don't have the body mass to reproduce as many eggs.
The overfishing pressure on the cod population was pushing the cod into an evolutionary corner.
They were having a harder and harder time surviving.
But what can be done to prevent other scenarios like this?
I mean obviously we need a better way to manage environmental resources.
Well, what do you guys suggest? Carol?
Hmm, uh, maybe privatize the resource?
A private owner would want to manage the resource efficiently in a sustainable way.
Ok, but the problem is privatization doesn't necessarily result in better management of an environmental resource.
Any ideas why it wouldn't?
Well, an individual owner might not properly assess the limits of the resource.
So they could be just as prone to overexploiting that resource as a group where lots of people have access to it.
Yes. Well, like in the 1970s,
when it was already clear the North American cod population was declining dramatically,
the US and Canada declared a 200-mile exclusive economic zone in the waters around Cape Cod.
By declaring an exclusive economic zone, you see,
these two countries were trying to extend their territorial waters.
Basically it was as if they were saying: 'we're the private owners. We own these waters. So we own the rights to the fish in them too.
Essentially the two countries told fishing vessels, trollers from all other nations, to get out of the cod fishing area.
You'd think that would be good news for the cod because there'd be less fishing.
However, The US and Canada wanted to expel foreign trollers only in order to increase the number of their own fishing fleets.
The total number of fishing trawlers actually increased.
Another possible solution, pass laws that regulate use of the resource.
But for regulation to be effective, penalties for breaking the law have to be large enough to deter violators. "
L40C2
"Listen to part of a conversation between a student and a university librarian.Mr. Reese. I am Jennifer Lee.
I worked on the photography exhibition last year, the one that was commemorating the university's 100th anniversary.
I helped select and display photos for the exhibit.
I helped set it all up, remember?
Oh, sure! You're the photography student that Professor Ryan sent to us.
How have you been?
Good. Thanks.
And I...uh...well, I was hoping I could talk to you about a job actually.
Oh, the job here in our library archive? Ha, that was fast! We just posted it yesterday.
Oh, no. Actually, it's for a photography job in the portrait studio at the mall.
Taking portrait photos?
Sounds like a great job for a photography student.
But how can I help?
Well, I went for an interview, but I still need to give them professional references from people I've worked for.
And well, I don't have a lot of work experience.
But you know, you've...you've seen how...
how I helped plan and carry a project through and showed up on time and everything.
So, I was kind of hoping I... you know, I could give them your name as someone they could talk to.
Of course, we all thought you did a great job.
I remember saying that to Professor Ryan and he thought so too.
I suppose you've already asked him for a recommendation?
I have, he's actually the one who convinced me to apply for it.
I wasn't sure I should. I mean, having real photography experience would be great for my resume, but...well...l am little concerned about the hours.
It's ten hours a week, which is fine, but they're all during the daytime.
I would have to schedule several classes for the late afternoon and evening.
I am not sure I will be able to do that.
Yeah, I see how that could be a problem.
Well, maybe you should consider the job I mentioned.
We just got a grant to hire a part-time library assistant for our photography archives.
It doesn't involve taking pictures, but it does involve working with pictures, filling requests for specific photos from students and professors.
And it's in the evenings from 6 to 9, three days a week.
Hmm, well, the hours are definitely better, but I really do want to find out about that job at the studio first.
I am sure you will understand. Of course, but if it doesn't work out, keep this in mind. "
L40L3
"Listen to part of the lecture in an environmental science class.Now, over the next few weeks, we're gonna focus on carbon and its role in what's known as the ""greenhouse effect.""
Everyone knows what that is, right?
But let's make sure anyway.
Yes, Karlie?
The greenhouse effect is when gases in Earth's atmosphere act like the glass in a greenhouse or a hothouse.
They trap in heat which warms up the earth.
Gases like?
Um, water vapor? Carbon dioxide?
Right. Carbon dioxide.
We hear a lot about carbon these days, no?
Carbon emissions, carbon burning, leaving a carbon footprint.
So it'd be easy to assume that any form of carbon burning is necessarily a bad thing.
But the fact is: it's not quite that simple.
So we're gonna focus today on the difference between good, bad, and well, the, not so bad, the potentially okay carbon burning.
OK. Good carbon burning.
Well, we all have a personal stake in this because burning carbon is the basis of life.
We wouldn't be here if we ourselves weren't burning carbon.
Basically, all living things burn carbon to survive.
Usually this happens at the cellular level and what's burned is carbon in the form of sugars, glucose.
Oxygen gets chemically combined with sugars in our cells and the energy produced from that reaction is then used to power the cells.
So just by breathing you could say we are all guilty of carbon emission and contribute to the amount of carbon in the atmosphere.
Um, another thing about atmospheric carbon: it keeps us from freezing.
Because without carbon and other greenhouse gases, our planet would be the same temperature as outer space,
around four degrees above absolute zero.
And there's nothing going on at that temperature.
No possibility of life of any sort.
So without atmospheric carbon, life couldn't exist on Earth.
Now, another thing to remember is that carbon is always being removed from the atmosphere.
It gets used up.
Largely it is consumed by plant life through photosynthesis.
Also, it dissolves in the oceans or gets stored deep in the ocean.
You have shellfish that use the CO2 dissolved in the water to make carbonate shells and when they die, they fall to the ocean floor and the carbon gets sequestered down there.
So with all this carbon constantly being depleted from the atmosphere, we really need to keep carbon output up to a certain point.
So why all the bad press for burning carbon?
Well, turns out it's the source of the carbon being burned that's the key.
It's in fact the burning of what we call ""fossil carbon"" that creates the imbalance: fossil fuels, coal, oil, natural gas.
These substances are all mined.
We have to dig them up or drill a well to release them.
And this is carbon that was in the atmosphere millions of years ago.
So what happens is: when we burn this carbon,
ok, it doesn't really release a whole lot compared to the amount that's already there in the atmosphere,
but it adds to the pool.
And over years it accumulates.
Think of the atmosphere as a big bathtub.
It's basically already filled to the brim with carbon.
When we start adding fossil carbon into the mix, it starts to spill over.
That being said, there's actually a category that's in-between: what we call biomass fuels, probably the most common one is wood.
Another example, um, on the North American plains, the Native Americans used to collect buffalo droppings to burn.
Uh, in Ireland, they cut up peat from bogs and they burn that.
So what's the big distinction between this and fossil carbon?
Biomass carbon is what we might call current carbon.
It's always going in and out of the atmosphere.
So if we burn one of these fuels, we're putting its carbon into atmosphere. Right?
But in a balanced system, somewhere else in the world the same amount of carbon is going back.
It gets taken in by growing vegetation.
So burning biomass fuel produces sort of not-so-bad carbon.
In fact, it can become good carbon if we endeavor as a society, as humanity,
to allow forests to recover this carbon,
if we don't, say, pave over all the surfaces to prevent things from growing.
So whenever we cut down a tree and burn its wood, we have to allow another tree to grow to keep things in balance.
That way, you're...you're carbon neutral. "
L40L4
"Listen to part of a lecture in a United States Government class.We've been talking about the basic services and facilities that an economy needs to function,
roads, bridges, rail systems, water supplies, power grids, and so forth.
What we call infrastructure.
Now, traditionally much of a society's infrastructure, particularly the transportation infrastructure,
has been owned and operated by states, by governments.
But lately, local and state governments have started to consider and sometimes actually enter into various deals to privatize parts of their infrastructure, particularly in the transportation sector.
And why is this privatization happening?
Well, as you may know, in the 1950s and 60s there was a tremendous highway building boom.
Governments created a huge interlocking network of highways with associated bridges and tunnels.
But these facilities are getting old now and they're becoming more and more expensive to maintain,
very expensive actually.
Tolls and tax revenues don't often cover all the needed repairs.
So why don't the governments just raise tolls and taxes?
Well, that's not so simple.
Government officials are elected by voters and voters get upset when their taxes go up.
And as for highways tolls,
commuters especially don't like paying higher tolls,
merely proposing increases can damage political careers.
So there's tremendous pressure on governments to find other ways to maintain infrastructure assets.
One solution is to sell or lease a part of the infrastructure,
a toll bridge, a tunnel, something like that to a private company,
usually a company that specializes in this sort of thing.
The idea is that the company that buys or leases a bridge or a highway or whatever will find it easier to keep it in good repair.
That will make commuters happy.
Right, there could be better service.
Since they are not government entities,
private companies face less political resistance, say to raising tolls in order to provide that better service.
But besides that, there's another reason governments like these deals.
States often have trouble paying their bills and they can use money they get from selling or leasing a piece of infrastructure to balance their budgets.
That all sounds good to me.
It does sound good,
but a lot of people are very wary of privatizing pieces of infrastructure and rightly so.
For instance, in almost every case thus far,
the first thing private companies do is drastically raise user fees because they say,
""Oh, we must do critical maintenance that's gone undone for years and years.
And because we're a private company,
we can't use tax money to do it.
Our only option is raising tolls.
But what's the impact on people who use a toll road to get to work?
What if a private owner doubles or triples the toll overnight?
Uh, users would have to spend a higher percentage of their income on commuting.
And depending on their income, that percentage could be significant.
But if tolls went up, me, I'd just avoid the toll road and take smaller back roads where there aren't any tolls.
That's a good point.
Secondary roads would become attractive to lots of other people too,
and private companies know this.
They also know that dramatic reductions in traffic would hurt their bottom line.
So market forces do play a role in keeping private companies from raising their tolls too much.
But the mere prospect of astronomical toll hikes is still alarming to governments when they think about selling or leasing parts of an infrastructure.
Now, from a business standpoint,
infrastructure purchases can be great investments!
If a company buys or gets a long-term lease on a toll bridge from the government,
it's got an almost guaranteed steady source of revenue for years and years,
which means that if the company decides it wants to sell the bridge to another company, say ten years from now,
it'll have no problem finding a buyer.
But what if that buyer, this new owner, continues to charge a high toll but doesn't do the same amount of maintenance because they want to squeeze more money out of the asset!
In that case, could the governments buy the asset back?
Well, to do that, it would have to raise money either by raising taxes or by selling bonds, both of which are politically sensitive.
So it's unclear in a practical sense whether these deals are truly reversible. "
L41C1
"Listen to a conversation between a student and an ecology professor.I have some good news for you.
One of the students who was signed up for the summer term at the field station next year won't be attending after all. Your name's first on the waiting list.
So if you still want to do it, the space is available.
Oh, that's terrific!
You were also interested in doing an independent research project next summer, right?
Yeah, on salt marsh restoration, but that was before, when I thought I wasn't going to get into the field station.
Well, you can still do it if you want.
I looked over your application for the independent research project, and it looks strong. I approved it.
And you'd have even more resources there at the field station, so...
The field station and an independent study, but the summer term is a few weeks shorter than a regular term.
Well, it's up to you.
You'd have to work hard but I think you can do very well.
Professor Garfield, one of the professors over at the field station...
Yeah, I've heard of him.
Yes, well. Professor Garfield has been doing research on salt marshes for years, assessing human impact and methods of salt marsh restoration.
He is willing to oversee your project.
Wow!
That's too good an opportunity to pass up.
I thought you'd say that.
When I spoke with Dr. Garfield, he suggested you take a particular course he'll be teaching here in the spring.
It's called advanced topics in salt marsh management.
The course looks at salt marsh ecology in depth and it also focuses on factors that stress salt marsh systems and how to assess and monitor the level of stress.
And that background information will fit right into my project on salt marsh restoration. This is so great!
Oh, one more thing. Do you know John Arnold?
Not really, but he lives in my dorm. Why?
John's another ecology student who will be the Field Station next summer.
I approved an independent research project for him, too. Initially, he had the same concern as you.
But anyway, his topic will be similar to yours.
He'll be researching how bridges and culverts1 that have been installed to allow tidal waters to move underneath roads between the sea and the salt marshes.
Well, they are often too small.
I guess that would result in not enough tidal water flowing into the marshes to maintain the natural vegetation, right?
Exactly, and he'll be looking at how to determine the right size.
So I was thinking he might be a good choice for a summer roommate for you. "
L41L1
"Listen to part of an enviromental science class.Many organisms have developed the ability to survive in harsh environmental conditions: extreme heat or cold, or very dry conditions.
Like plants in the desert.
Your textbook doesn't have much about the specifics on desert plants, but I think that desert plants are great examples of specialized adaptations to extreme environmental conditions.
So, with desert plants, there are basically three different adaptive strategies.
And I should point out that these strategies are not specific to any particular species.
Many different species have developed each of the adaptations.
So, first off, there are succulent plants.
There are many different species of succulent plants, but they all can absorb and store a lot of water.
Obviously, opportunities to get water in the desert are few and far-between.
Generally rains are light and short.
So the rain doesn't seep too far down into the soil.
And there's a limited window of time for any plant to get the water before it evaporates.
But succulent plants have a spread-out and shallow root system that can quickly pull in water from the top inches of soil, though the soil has to be saturated since succulents aren't good at absorbing water from soil that's only a little moist.
Succulent plants also are well suited to retaining water, important in an environment where rainy days are rare.
Succulent plants can store water in their leaves, in their stems, or in their roots.
And to keep that moisture from evaporating in the hot, desert Sun, most succulent plants have a waxy outer layer that makes them almost waterproof when their stomates are closed.
They also preserve water by minimizing their surface area.
The more of the plant that's out in the Sun, the more potential there is to lose stored-up water.
And that means that most succulent plants have few, if any, leaves.
Now, besides succulent plants, there're also drought-tolerant plants.
Drought-tolerant plants are like bears in a way.
You know how bears mostly sleep through the winter.
They can survive without eating because their metabolism slows down.
Well, drought-tolerant plants also go into a dormant state when resources, in their case, water, run short.
A drought-tolerant plant can actually dry out without dying.
I said before that most desert rains are light and brief, but occasionally there is a heavy one.
Drought-tolerant plants revive after one of these significant rainfalls.And they are able to absorb a good bit of the rainfall due to their deep roots.
Actually the root system for drought-tolerant plants is more extensive than the root systems of many plants that live in wetter climates.
Droughttolerant plants can even absorb water from relatively dry soil because of their deep roots in contrast to succulent plants.
The third adaptive strategy is to avoid the drought conditions altogether.
Yes! There ARE plants that do this: Annual plants!
An annual plant will mature and produce seeds in a single season that will become the next generation of annual plants.
In desert conditions, annual plants grow in the fall or spring to avoid the heat of summer and the cold of winter.
Of course, these plants could face a serious problem if a particular fall or spring happened to be very dry.
They would have difficulty growing and could die before producing seeds.
But they have a mechanism to prevent one year of low rainfall from wiping them out.
Not all seeds an annual plant puts out will grow the following year.
Some seeds remain dormant in the ground for several years.
It's a type of insurance that protects the annual plants from a season of poor growing conditions, of unfavorable weather. "
L41L2
"Listen to part of a lecture in an united state history class.It's interesting how much we can learn about culture in the United States by looking at how Christopher Columbus has been portrayed throughout United States' history.
So let's start at the beginning.
Columbus' ships first landed in a... landed in the Caribbean.
There's some debate about which island.
He landed in 1492, but it wasn't until 300 years later in 1792 that his landing was first commemorated.
And this was the brainchild of John Pintard.
Pintard was a wealthy New Yorker, the founder of the New York Historical Society.
And he decided to use his influence and wealth to find a great hero, a patron for the young country.
And he chose Columbus.
And in New York, in 1792, the anniversary of Columbus's landing was commemorated for the first time.Now, other cities, uh, Philadelphia and Baltimore followed. And...
But why Columbus?
And why there?
Well, to Pintard it was a way to build patriotism in the young, politically fractured country.
Remember, the United States had only declared its independence from Britain 16 years earlier, and had yet to form a national identity.
Pintard also had a hand in helping to create Independence Day, you know, July 4th; as a national holiday.
So you see that he was very involved in creating sort of a national story for Americans.
And Columbus, he felt Columbus could become a story that Americans could tell each other about their national origins that was outside of the British colonial context.
The United States was in search of a national identity.
And its people wanted heroes.
But why not some of the leaders of the revolution?
You know, like George Washington.
The leaders of the revolution were the natural candidates to be heroes, but many were still alive and didn't want the job.
To them, being raised to hero status was undemocratic.So Columbus became the hero.
And the link between Columbus and the United States took hold.
And so what was that link?
Well, Columbus was portrayed as entrepreneurial, someone who took chances, who took risks, and he was cast as somebody who was opposed to the rule of kings and queens.
Perhaps most of all, Columbus was portrayed as someone who was destined to accomplish things, just as America in those early years was coming to see itself as having a great destiny.
But Columbus was supported by the king and queen of Spain. He wasn't against them.
True.
To be historically accurate, the way Pintard thought about Columbus doesn't match up with the facts of his life at all.
And I really have to stress this: the fact that Columbus became the hero of a young country had little to do with Columbus, anything he did, and a lot to do with what was happening in the United States 300 years later.
Columbus was extraordinarily adaptable to the purposes of America's nation builders, people like John Pintard in the early part of the 19th century.
And since not a lot of facts were known about Columbus, because writings weren't available in North America until...until 1816.
That might have actually helped the process of adapting him to American purposes.
Since no one knew much about the real Columbus, it was easy to invent a mythical one?
Exactly.
And this mythical Columbus, it became a reflection of the society which chose him.
So in the early history of the United States, Columbus represented an escape from the political institutions of Europe.
He was the solitary individual who challenged the unknown.
And now there was this new democracy, this new country in a world without Kings.
Columbus became sort of the mythical founder of the country.
So as historians, we wouldn't want to study these myths about Columbus and mistake them for facts about Columbus.
But if we are trying to understand American culture, then we can learn much by studying how America adapts Columbus for its own purposes.
Evaluations of Columbus then will reflect what Americans think of themselves.
Oh, there is a quote, something like, ""societies reconstruct their past rather than faithfully record it.""
And how that reconstruction takes place and what it tells us, that's something we are going to be paying a lot of attention to. "
L41C2
"Listen to a conversation between a student and a financial aid official.Hi, can I help you?
Yes, I'd like to get help with the, you know, payment for my classes, some sort of financial aid.
The problem is I don't know much about it, so I don't really know where to begin.
I saw this poster about work-study programs.
Can you tell me something about that?
Well, I think you're talking about the government sponsored work-study program.It works like this: you work on campus and get paid an hourly wage just like a regular job.
However, instead of getting a paycheck, the money goes directly to your bill for your courses, but almost all work-study jobs pay minimum wage, which is usually pretty low.
The truth is: you might do better getting a job off campus since you can do whatever you want with the money, like paying your rent or...or buying textbooks.
Thanks!
That's very useful.
So how do I find out what's out there?
Let me show you our catalogue of various programs as well as scholarships offered here.
That's your best bet1 really, if you can find a good scholarship, because you don't have to pay the money back.
You might qualify if your grades are good enough or if you have the right background.
Yeah, that sounds like something I should try for.
Now, this is my desk-copy of the catalogue, but I can give you your own copy if you want. Oh yeah, be sure to visit the university library, too.
There's a whole section on financial aid including application forms.
Why isn't all the information listed in the catalogue? It'd be so much easier.
Oh, if we did that, the catalogue would be too heavy to pick up.
City clubs, foundations, organizations from all over the country offer scholarships or other financial assistance to college students, and all kinds of companies have programs to help their employees' children go to college.
If either of your parents works for a large corporation, have them check to see if their companies do that.
Okay. Good idea.
Hey, my dad works for a big accounting firm and he's a member of a professional accounting organization.
Do you think they'd offer financial aid?
Yes, that's fairly common, especially if you are planning to go into accounting.
What are you studying?
What do you plan to do after you graduate?
I want to become a dentist.
I'm enrolled in a pre-med program for dentistry.
Okay. So I'd suggest looking in the library for information on organizations that have to do with dentistry.
Any number of them might offer scholarships to students planning to join their profession.
I'll definitely investigate that one.
Great! But be sure to talk to one of our librarians, too.
They get the same questions over and over, so they can save you a great deal of time. "
L41L3
"Listen to part of a lecture in an art history class.OK. As art historians, one of our fundamental taste is to assign ownership to works of art, right?
We're presented with a work of art, and we have to figure out who made it.
But this task becomes particularly difficult when we're dealing with works produced in Italy during the Renaissance, the 16th, 17th centuries.
Now, why is this the case?
Anyone? Emily.
Um...is it 'cause artists didn't sign their work?
I mean, didn't the whole concept of the artist as an individual developed later? In like the 19th century?
Well, you are sort of on the right track.
The concept of the individual artist, especially the concept of the artist as an artistic genius struggling alone with a vision as opposed to...say...a mere artisan...well, the idea of the artist as a lone genius didn't develop until later.
But artists, individual artists, did sign their work during the Renaissance.
In fact, you could say that's part of the problem.
Paintings were signed by the artist and that used to be understood to be a mark of Renaissance's individualism.
If a piece had Raphael's signature on it, we assume it was done by the great artist himself Raphael, in the singular.
But you see, art in Renaissance Italy was very much a collaborative business.
Painters and sculptors worked in a workshop.
It was almost like a small business run by a master artist.
You see, to deal with a wide variety of commissions they received, orders basically, for specific types of art, specific projects, to handle these, master artists often employed assistants as apprentices.
And this was especially so if they worked on a large scale, huge paintings or sculptures, or if they were much in demand, like Raphael, for instance.
He worked on some large paintings.
He painted frescos for the Vatican1.
He also received a great many commissions.
There's no way he could have completed every part of every project all by himself.
Now, these assistants might work for the master artist on a temporary or a permanent basis.
And they might also specialize.
For example, in Raphael's workshop, which might be called Raphael incorporated, one of the assistants specialized in animals.
He actually painted a good number of the animals in Raphael's art.
It maybe that a master signing a work was simply making a declaration that the work met the standards of the shop.
And it wasn't just painters.
Sculptors also worked together.
In fact, assistants were even more necessary if you were a master sculptor because statues take longer to make than paintings.
And the master had to arrange for marble to be quarried, things like that.
Perhaps the most collaborative of all was architecture.
There we see a real division of labor, but with carpenters, masons, unskilled labor just to carry materials to and fro, and so on.Plus, of course, your skilled artisans who carried out the master architect's design.
Think of it, like, um, a ballet, you know.
All the dancers work together.
There's a division of labor. People have different roles.
And in order for the thing to come together, everyone needs to be aware of what others are doing and coordinate their work and have good timing.
So for architecture, it's almost impossible to know who was responsible for any given detail.
Was it the master architect?
The mason? An assistant mason?
Maybe it was even the patron, the client who was paying for the art.
Remember, it wasn't yet customary for architects to give their assistants measured drawings to work from.
Instructions were given orally, not in writing. So we don't have those documents to tell us what exactly the master architect's plans were.
The only time we have written records is when the architect wasn't actually there.
Perhaps the architect was away on business and had to write out instructions and send them to the shop.
And another thing to think about: What effect do you suppose this approach would have had on innovation?
I mean, since the hired artisans had been trained by other artisans, they tended to be trained to use traditional styles and techniques.
So if you're a master architect, uh, you've developed your own style.
Say you're calling for certain detail in the building you're designing, right?
And say this detail is different, purposely different, from the established tradition, the established style.
Well, most likely when the hired artisans would execute the design, rather than follow the intended design, they would stick with the more traditional style that they were familiar with.
Workers would have to be supervised very closely to prevent this from happening.
Otherwise, as it often happened, there goes the designer's style and creativity. "
L41L4
"Listen to part of a lecture in an astronomy class.OK. We've been discussing the planets in our solar system and how some of the ones farthest from the sun were discovered.
Well, today I'd like to turn to what are called exoplanets and how researchers detect them. Maria?
Exoplanets are planets that orbit around a star other than our Sun, right?
They are not in our solar system.
Right. They have different...what are called ""host stars"".
And the study of exoplanets has been getting more and more exciting. Hundreds of them have been discovered so far.
This is quite remarkable in view of the fact that the discovery of the first exoplanets was confirmed only in the mid-1990s.
Now we're finding new ones every few weeks or so.
So, uh, exactly why are we interested in these exoplanets anyway?
Is it to see if there's life on them?
Cuz it seem to me like the only exoplanets we ever hear about are gas giants like Jupiter and Saturn that couldn't possibly support carbon-based life.
OK. Well, let's talk about that.
First, as for discovering life.
Well, I think that sort of discovery is pretty far in the future, but it is an eventual goal.
For now, the focus is on locating planets within a host star's so called ""habitable zone"", a zone that's a certain distance from its star because only planets within this zone could conceivably support carbon-based life.
So, what would such a planet need?
Water?
Yes, it need to be the right temperature to sustain liquid water.
And it would need to be a rocky planet, I mean, as opposed to a gas giant.
OK, good. An Earth-like planet.
Now, as to that, there are some recently detected exoplanets that might actually be Earth-like.
For example, there's a red dwarf star, that's what most stars are, um... that's called Gliese 581.
Gliese 581 is... well, it's a lot more interesting than that name makes it seem.
This host star is considered a near neighbor of our solar system because it's only about 20 light years away.
It's pretty close by astronomical standards.
And being a red dwarf star, it's small and relatively cool, at least compared with the Sun.
And researchers have discovered planets orbiting Gliese 581.
These exoplanets have been named, ready? Gliese 581 b, c, d, e, in alphabetical order of their discovery.
Gliese 581 d and e are the planets I wanna focus on now.
See, in 2009, a group of researchers made an announcement.
These two exoplanets: Gliese 581 d and e do have some Earth-like qualities.
Gliese 581 d had actually been discovered a couple of years earlier.
And when its orbit was originally calculated it was thought to be too far away from its host star to be warm enough to support a liquid ocean, let alone carbon-based life.
But then its orbit was recalculated and now we see that Gliese 581 d is within its host's habitable zone.
So it might have an ocean?
Well, conceivably.
See, Gliese 581 d weighs 7 times what Earth weighs and it's unlikely that it's made entirely of rocks because it's so massive.
The researchers studying it said that it could have a rocky core, an ice layer, a large deep ocean and an atmosphere.
OK, and there was another announcement along with the recalculated orbit of Gliese 581 d.
That was the discovery of another planet in the system, Gliese 581 e.
Compared with other exoplanets, its mass is quite small, only about twice that of Earth.
So is Gliese 581 e a more Earth-like planet?
Well, we have to consider its orbit.
Gliese 581 e orbits its host star in a much shorter period of time than the other planets in the system, meaning it's very close to the star, and therefore too hot for water, for an ocean.
However, the fact that it's relatively close to the size of Earth, small, in astronomical terms, that was pretty exciting.
It's impressive that we have the technology to detect it and it bodes well for future research.
Who knows what we'll find the more we search. "
L42C1
"Listen to a conversation between a student and an art history professor.Hi. I'm Melisa.
I was just a few doors down getting some help in the computer lab.My electronic files won't open.
The technician says it's probably a computer virus. She's working on it now.
Yes, from what I've heard lots of campus computers have been affected.
What a first week! Huh?
I know, anyhow, I noticed your name on the door as I was walking down the hallway, thought I'd stop in and find out if you happen to have any additional copies of the class syllabus.
The one I received in class the other day is missing a page.
Oh, sorry about that.
I probably have a few extra printouts on hand.
Great! Oh, and I noticed on the syllabus we'll be learning about and eventually writing a paper on ""The Bauhaus1 style of art""?
Sounds interesting. Tm looking forward to it.
Right, but technically it doesn't say Bauhaus style of art.It only says the Bauhaus.
Oh, what's the difference?
Well, the Bauhaus is not really an artistic style like cubism.
It was the name of an art and design school in Germany in the early 20th century.
The Bauhaus was started as an experiment in education, and one ground-breaking technique used in its teaching was that students actively participated in workshops instead of just sitting in classes.
Interesting! I don't have much background in order or anything.
I'm an economics major and Tm taking this class as an elective, decided I wanted to broaden my awareness, try something new!
Excellent! I'm really glad to hear that.
So, was the focus of the Bauhaus architecture, I mean, I studied German and Bauhaus translates into ""house for building""...
Well, the founding director was an architect.However, he aimed to combine an incredibly broad variety of fine arts and crafts under one artistic roof.
As a matter of fact, when the Bauhaus first opened, it was without an architecture department for several years.
But later, it became very influential in architecture.
So I wasn't all wrong.
You'll see on the syllabus that you are required to visit the Rutherford Museum exhibit.
The exhibit will help you see that there is no single Bauhaus style.
I think it;s refreshing that this particular exhibit departs from the standard ways in which art from the Bauhaus is often presented.
Which are?
Well, for example, by a specific artist.
I think it's a mistake to focus on a single Bauhaus artist and that person's individual specialty.I mean, the different artists from the school created different things: fabric, sculpture, furniture, graphic design, paintings, even theatrical performances.
The exhibit in the Rutherford Museum unite all these specialties through connecting themes such as motion or the body.
Sounds fascinating!
Say, I've heard of something about discount nights at that museum?
Weekends are full price.
It's typically best to go Thursday nights.
That's student discount night, 50% off However, next Wednesday is open to the public for free.
It's a special promotion.
So I know what I would do. "
L42L1
"Listen to part of a lecture in an art history class.I am sure you've all been to museum, where you've seen beautiful white marble statues sculpted by the Greeks and Romans, or at least that you've seen photos of such statues, right?
We've come to expect these classical Greek and Roman statues to be monochrome, just one color, white skin, white hair, white eyes, white everything, the natural color of the marble they're carved from.
Now, the ideal of plain white sculpture goes back to 15th century Europe when Renaissance artists rediscovered ancient Greek and Roman culture.
They were inspired by sculptures that appeared monochrome so they created white marble statues.
The impact of these Renaissance statues, such as Michelangelo's David, gave rise to new standards for sculpture, standards that emphasized form rather than color.
But what if many of those ancient statues were originally polychrome, colored from head to toe?
Early in the 19th century, archeologists found traces of paint on ancient sculptures and since then, classical art historians have begun to realize that Greek and Roman marble sculptures were originally colored.
Even if an ancient marble statue doesn't have any visible traces of paint, that does not mean it was originally monochrome.
In many cases, the pigment would've simply deteriorated.
Ancient artists used mineral-based paints with organic binding media that would've disintegrated on its own overtime.
In other cases, the pigment may have been weathered away while exposed to the elements or someone may have rigorously cleaned the statues and unknowingly removed the last traces of pigment.
So, the fact is, we do have evidence of polychrome sculptures from Greece and Rome from the 7th century B.C.E. all the way through at least the third or fourth century C.E.
It's now generally accepted that most, maybe even all marble sculptures from that time period, receive some kind of surface treatment, like the application of pigments, colored stones or metals that would've modified their color.
So do we interpret the statue differently if we had known it had originally been polychrome?
I feel strongly when it comes to this.
A marble sculpture that had been colored has another layer of meaning that was meant to affect the viewer.
As art historians, we must try to interpret the intentions of the artists.
What were the artists trying to achieve?
Certain features of the sculpture were highlighted through color, were made to stand out.
In other words, they caused the viewer to focus on certain features.
And certain colors represented certain things to the ancient artists and cultures.
A color might symbolize heroism, divinity or youth.
One example to consider is the statue of Roman emperor Augustus.
This particular statue of Augustus that I am referring to was discovered just outside of Rome in 1863 and was in terrific condition.
It's about 2 meters tall, just larger than life size.
It was made from an expensive high quality type of marble and was obviously carved by an expert.
Now, it still had visible traces of color on the hair, eyes and its clothing and armor.
The paints have been very carefully studied.
And it turns out that the colors weren't just from any pigments.
They were from expensive pigments.
The use of these pigments showed the importance of Augustus and that he should be honored.
And let's consider the extensive traces of a red pigment that were found on the statue's cloak.
The cloak is a special garment that was traditionally worn by an emperor on the battlefield.
And in real life it was a red color, which to the Romans, signified the emperor's authority, military and political authority.
Ok, I won't point out any further details about the colors on the Augustus statue, because you can already begin to see that there was cultural importance associated with the colors, symbolism, which should help us understand the status better.
There are many, many more sculptures that have traces of pigments left on them and we have the technology these days to be able to carry out effective studies of these pigments.
There is a lot of work to be done, but it needs to be done fast.
Like I said before, these pigments deteriorate rapidly so we really need to do the research before the traces are gone so that we can increase our understanding of ancient polychrome sculptures and the cultures which created them. "
L42L2
"Listen to part of a lecture in an astronomy class.Before we continue talking about the properties of individual galaxies, it's worth talking about the distribution of galaxies in space.
Efforts at mapping or surveying the universe, making a sort of atlas of galaxies, have been going on for more than 50 years.
And the creators of the first major map of the universe were the astronomers Harlow Shapley* 1 and Adelaide Ames.
In 1932, Shapley and Ames3 catalogued the positions of 1250 galaxies by photographing what they saw through their telescopes.
And they made an important discovery.
Their survey was the first to indicate that galaxies were not distributed uniformly in space.
Some areas had a lot of galaxies, and other areas had just a few. Another way of putting this is to say that galaxies are clustered.
They're not spread evenly throughout the universe.
So we have stars grouped together in galaxies and galaxies grouped together in clusters. Okay?
Now, after their survey, other astronomers completed surveys that added to the number of clusters catalogued.
One of the most important was done by the astronomer George Abell4
Abell completed his survey in 1958.
It added considerably to the map made by Shapley and Ames.
In fact, his map had over 2700 clusters of galaxies.
That is 2700 clusters of galaxies! Not just galaxies.
But there's another aspect of Abell's work that makes this map so valuable to astronomers.
He introduced a classification scheme for the galaxy clusters5
Now, surveys completed since Abell's have catalogued additional galaxies and surveyed more outer space, but no one has improved upon Abell's classification scheme.
In fact, the Abell catalogue is used as a starting point for astronomers who study these objects.
One of the reasons his scheme has been so widely accepted is because of his sample size.
With all the clusters in his sample, he could determine the different characteristics of clusters.
And these characteristics form the basis of his classification scheme.
Now, two of the characteristics crucial to his classification were richness and symmetry.
So what did he mean by ""richness""?
Well, basically it refers to the number of galaxies there are within a cluster.
Is that the same as density?
That's right. Both richness and density refer to the number per area.
Rich clusters, or dense clusters, contain a relatively high number of galaxies.
And symmetry just refers to its shape?
Roughly speaking, yes.
Whether the shape of the cluster was the same on the left side as on the right side.
So Abell use categories like that to classify clusters on a scale: from regular to irregular.
A regular cluster is sphere shaped, symmetrical, and most dense in the middle.
The greatest number of galaxies concentrated in the middle of the cluster.
An irregular cluster might appear to be lopsided, asymmetrical, with a little concentration of galaxies in the center.
You are talking about the shape of the cluster though, not the shape of the galaxies within the cluster.
Right.
For example, let's consider the Coma Cluster.
It's a symmetrical cluster basically spherical in shape, but the individual galaxies within it are elliptical. They're not spherical or spiral shaped, but the cluster itself shows spherical symmetry.
The Virgo Cluster, on the other hand, is considered irregular.
There's no symmetry to its overall shape, no central concentration of galaxies, but it happens to have both elliptical and spiral galaxies within it.
Another question. You were saying how some clusters have more galaxies than others.
How many galaxies does a cluster have to have in order to even be a cluster?
Good question!
Abell's definition of a cluster is this:
First, there have to be more than 50 galaxies within a specific amount of space.
He said basically that clusters have a radius of roughly 2 megaparsecs.
And it was just an assumption that all clusters would be about the same size.
It's remarkable that it proved to be correct.
And this standard cluster radius is known today as ""The Abell Radius"".
And second, those 50 plus galaxies have to be a certain brightness.
Of course it was a rough estimate, but looking at galaxies' brightness was a good way to distinguish between clusters that were nearby and those that were more distant. "
L42C2
"Listen to a conversation between a student and a university activities coordinator.I understand your problem, but the upper level of the Student Center isn't available for the time being.
But my dance group has a performance coming up.
I've been talking with people all day long who are in the exact same situation.
There are at least a dozen dance and drama groups on campus, and they are all scrambling for rehearsal space right now.
But I made this reservation last June, before leaving for the summer.
No one said anything about construction.
That's because no one knew that the remodeling was gonna run over into the beginning of the school year.
The builders are just way behind schedule.
For a while, we weren't even sure that the dining hall on the lower level would be ready for the start of the semester.
So, it could've been a lot worse.
So when will...?
The whole upper level will be ready in six weeks.
The rehearsal rooms, the game room, the computer center.
Six weeks!
That's not gonna help me.
Our performance is in five weeks.
Are you part of the program they plan for parents' weekend?
Yeah, the thing is we are a tap dancing group, and we need to practice on hard floors, preferably wood.
We can practice on carpet at first, but it's important for us to be able to hear our feet hit the floor.
Interesting, uh, because of the rhythm, huh?
Yeah, because the taping becomes part of the music.
So the floors are very important.
Exactly, and just about everywhere on campus has carpeting.
Well, there's always the stage at the student theatre.
Though it's a long shot, we can look at the schedule.There might be some odd hours free.
What about in town? Do you think the university could help us rent a rehearsal space in a commercial dance studio in town, given the situation?
That's not really my call.
I can reserve rehearsal and performance spaces on campus for you, but off campus...
So who would I talk to?
The dance department?
Look, let's check the theatre schedule first. "
L42L3
"Listen to part of the lecture in an environmental science class.When you try to imagine a fungus, you'd probably picture a mushroom popping up out of the ground.
And think that's it.
But a fungus like that...most of it actually lives underground.
And fungi in general are often an important active component of the soil.
A fungus secretes enzymes into the soil, enzymes that break down, decompose organic material in the soil.
So the fungus can absorb this material and get nutrition.
But to me, what's most interesting about this process is how it may enable fungi to help clean up environmental pollution in the soil.
And that's thanks in part to a substance in their cell walls called Chitin.
Now a lot of people think fungi are related to plants, but they are not. Believe it or not, the only other place chitin is found in abundance is in the exoskeletons of insects, crabs and such.
So in this sense, fungi are more associated with insects than with any plant. Strange, huh?
And the chitin in the cell walls of a filamentous fungus...a filament, of course, is a long thread-like structure, cells joined end to end.
Filamentous fungi grow in soil and in decaying vegetation.
And as their name implies they exist as filaments.
And although regarded as microorganisms, filaments from a single fungus can fan out to occupy many square meters or even several square kilometers of forest floor.
Their vast surface area allows them to break down and take in huge amounts of nutrients, but beyond that, the filaments also pull out of the soil a great deal of the pollution that might be in there, especially heavy metals.
And here is where chitin comes in, like some other substances in fungal cell walls, chitin forms strong chemical bonds to heavy metals in the environment, in a process we call adsorption.
Now, don't confuse this with absorption, where a substance is absorbed into a cell, into the interior of a cell.
I mean, that is happening here too.
But adsorption means binding to the outer surface of the cell.
And a filamentous fungus can adsorb toxic heavy metals, bind them to the surface of its enormous network of filaments, and thereby detoxify a large soil ecosystem.
The heavy metals are still there, but instead of leaching into the water system and contaminating the water underground, large amounts of these metals may remain bound to the chitin, to the cell walls of filamentous fungi in the soil, and thus remain chemically inactive for as long as 30 years, perhaps longer.
In fact, we can actually use the cell walls of filamentous fungi as a filter, even after the fungi are dead.
For example, the pharmaceutical Industry grows filamentous fungi in large quantities in the lab, like to produce the antibiotic penicillin, the drug company grows the fungus penicillium, and after the penicillin is extracted, these dead penicillium filaments, we can use the chitin in their cell walls to make industrial filters to adsorb heavy metals.
We can put these filters into waste pipes from industrial processes, and use the filters to trap heavy metals, like mercury and zinc.
Later, we can chemically extract the heavy metals and reuse the filter over and over.
Now going back to the absorption of toxic metals into the body of the fungus, let's turn our attention to mushrooms.
Like other fungi, mushrooms can absorb large quantities of heavy metals.
In fact, they may contain up to two and a half times the concentration of toxic metals found in the soil they grow in. So mushrooms, at least what we see above ground...we can potentially harvest them and then once for all safely dispose of the pollutants contained within them.
In fact, to clean up, especially the groundwater system, permanently, harvesting mushrooms is probably the best way to go.
For some reason, this hasn't happened yet as far as I know, but I can easily envision cultivating mushrooms for the sole purpose of detoxifying a large underground ecosystem. "
L42L4
"Listen to part of a lecture in a marketing class.And that wraps up our discussion of how the retail sector, uh, ways in which retail managers deal with customer complaints.
So let's shift now to the service sector, which markets not goods but services, intangibles like transportation, food service, career counseling...
Oh, there are literally hundreds of examples.
Service providers must, of course, constantly strive to meet customers' needs.
But as in retail, there are instances of service failure in which the customer is dissatisfied, uh, perhaps to the point of not doing business with you anymore.
Some service failures are beyond an organization's control, like, uh, computer malfunction that leads to missed deadlines.
Other failures stem from process problems, like inadequate training for newly-hired employees.
Then there's human error.
Okay, imagine you manage a car rental agency.
A customer calls in a reservation, but your employee marks down the wrong date.
So your customer arrives and guess what, the size car he reserved isn't available.
But your customer is less concerned about the source of the failure than the solution: what you do about it; what sort of compensation; what service recovery you give.
So if you are in the service industry, as a marketer, you always need some kind of service recovery plan.
Your plan must be in place before a failure occurs and it must also be communicated promptly to everyone in your organization who deals with customers so they'll know what to do.
Service recovery encompasses all the actions taken to get a disappointed customer back to, uh, well, back to a state of satisfaction.
So if your car rental agency couldn't provide the size car your customer wanted, but your policy is to provide a roomier car for the same price.
Your customer would probably be happy, might even restore his faith in your company.
Research has in fact identified service recovery as a significant determinant of customer loyalty.
I see what you mean.
Every year, my family goes on vacation together.
And a few summers ago, when we were in Chicago, it was really really hot. And guess what, the hotel's air conditioning broke and everyone was complaining.
What the hotel did...they actually didn't charge anybody for that weekend.
But the funny thing is that even though we had that horrible experience at that hotel, because they were so quick to appease us, we usually stay at that same hotel every time we go to Chicago.
Great example!
So in this case that hotel chain might consider itself the beneficiary of the so-called service recovery paradox.
Um, the paradox basically implies that customers who experience a service failure, well, they could potentially be made more loyal than customers who were satisfied in the first place if an equitable recovery occurred after the failure.
Yes, Ben?
Wait a minute.
If a good service recovery creates more loyalty than, um, if things went smoothly from the get-go1 , why don't companies like make mistakes on purpose so?
So you could implement a recovery plan that leave your customers delighted as opposed to merely satisfied?
Look, it;s always better to do things right the first time 'cause how how can you know that the paradox will hold true in every situation?
Plus, it's hard to predict if a good service recovery will overcome the negative effect of a service failure, and what about all those failures that never come to your attention?
Because statistically about 50 percent of the customers don't complain about service failures, at least not to the service provider. But negative word of mouth, now, that got worse implications for your business.
Also, you'd have to pay your employees to execute the service a second time.
Typically, a service recovery is gonna involve some kind of compensation, right?
So it is gonna cost your company some money that you are going have to account for in your budget.
I've actually been researching some of these issues myself 'cause what we need is a deeper understanding of customers' thought processes and their reactions to service recoveries.
How do consumers form expectations?
How do they react to different service recovery tactics?
Can we predict how any given customer will react to a given service failure?
People's expectations, their priorities vary.
Like uh, if I am in a hurry, and the French fries I ordered at a fast food restauran aren't piping hot2,1 might not complain 'cause I got them fast.
But If I am not in a hurry, I might return the fries even if I had to wait for a fresh batch. "
L43C1
"Listen to a conversation between a student and a computer lab administrator.Excuse me. Do you know that all the printers over in the student center have stopped working?
There are eight printers connected to the computers there.
You are saying they are all broken?
Yes, I just came from there.
There's a lot of frustrated students.
So many classes have papers due this afternoon that everyone is trying to print out their stuff at the same time.
Those printers got overworked and now they all have paper jams or some other problem.
Can you fix them?
Well, not really. I'm just an administrator. Most of our actual technicians are students who take the job on the side.
Where are they?
Well, most of the students who work at the computer labs study at the engineering school, and unfortunately they all took the day off.
I think they have some big exams tomorrow.
How can there be no technicians working on the biggest deadline day of the semester?
Well, there is one technician working at the computer lab in the arts building.
Actually, he just sent me an email message saying there was a huge crowd there, and he could not figure out why.
Because people need to print their papers.
There must be something you can do.
People need those printers working.
Well, we just ordered new printers and next month we are replacing the old printers over the student center with a brand new set of printers.
But the deadline for submitting papers is just two hours away.
I'm afraid there's nothing I can do. Your best bet is to probably head to the arts building and get in line there.
But how did this happen again?
Last semester when the all printers broke down, the president of the college got involved.
He sent out an email message to all the students saying that he was going to personally do something to make sure that the situation was resolved.
That's right.
When we had our budget meeting at the beginning of the semester, the president was there.
That's not something he usually does, but he wanted to make sure we ordered the new printers.
The new printers that are coming next month?
Yeah, I ordered them as soon as the budget was approved.
It's a shame. But the purchasing process being what it is...
You know what? It's possible some of the printers are malfunctioning because they ran out of ink.
I'm not a technician, but if that's what's wrong I could fix it.
I guess I'll grab some ink cartridges and go over to the student center and check.
No guarantees, sorry, but it might fix the problem. "
L43L1
"Listen to part of a lecture in a botany class.It's autumn and as you know in most parts of the United States, the leaves on the trees are changing color from green to yellow, orange and lots of other colors.
So this will be a great time to talk about how and why some of these leaves turn one color in particular and that's bright red.
Well, before we discuss why leaves turn red, first, let's, um, look, I know this is very old material, but just to play it safe, let's first go over why leaves are usually green.
It's chlorophyll, right?
Leaves get their green color from chlorophyll, the chemical that's responsible for photosynthesis.
The chlorophyll in the leaves collects energy from the Sun in the form of sunlight and it converts this energy into sugar which is food for the plant.
It's chlorophyll that makes leaves green most of the time.
Now, the classic explanation for why leaves change color is this.
In autumn, the leaves start preparing for the winter and stop synthesizing new chlorophyll.
Since chlorophyll is sensitive to sunlight and to cold temperatures both of which you get in autumn.
The existing chlorophyll in the leaves breaks down and since it's not been replaced by the new chlorophyll.
The green color of the leaves gradually fades away.
As this happens, the other pigments present in the leaf become visible. According to the classic theory, this is true for the red pigment as well.
It was there in the leaf all along but it was hidden by the green chlorophyll.
OK, so that's the classic explanation and it's partially right.
Why do I say partially?
Well, it's probably true for pigments like yellow or orange, but it doesn't seem to hold for the red pigment.
Let's back up a bit.
Just what produces this red color in leaves?
It's a red pigment called anthocyanin.
Here is where the classic explanation doesn't seem to apply to red.
What's interesting is that during the summer there was very little if any anthocyanin in the leaves.
But in the weeks before a tree is about to drop its leaves, the production of anthocyanins increases significantly.
In other words, unlike those other pigments, anthocyanins are not just unmasked by the breakdown of chlorophyll in autumn.
They are actually created at this time.
So that raises a question, why would a tree produce more anthocyanin just before dropping its leaves?
Why does the tree spend so much of its resources doing this just before the leaves fall off?
On the surface, that doesn't make sense.
It'd be likes spending money to...I don't know...to have your old car repainted when you know the car's not going to last more than a couple of months.
All this extra anthocyanin in the autumn seems like a waste.
But remember nature is very economical with its resources.
So that means anthocyanin must be serving some function that's important for the tree.
Today, there are some theories about what that function might be.
One of them involves predatory insects; another involves fungi.
You know, the more I read about these theories and the related research, it always created more questions for me than answers.
So I was really glad to learn about a totally different theory, a new one. It seems to come with research and data that give a full explanation.
So here it is.
Remember I said the chlorophyll breaks down?
Well, in autumn, a whole lot of other chemical constituents of the leaf break down as well.
I don't mean they are totally destroyed 'cause actually they break down into other different chemicals that the tree can reabsorb from the leaves and reuse later.
Now, this reabsorption process is very important for the tree and here is the key.
It's sensitive to light, meaning that too much exposure to sunlight can interfere with this process.
So where does anthocyanin fit in here?
Well, anthocyanin is more stable than chlorophyll.
It's not harmed as easily by the Sun or the cold.
So it's still working long after the chlorophyll breaks down.
But what does it do?
The theory is that anthocyanin protects the reabsorption process from the sunlight.
For example, if you look closely at a red leaf on a tree, you'll notice that most of the red pigment is on the upper side of the leaf, the side facing the sun.
This new theory suggests that what the anthocyanin is doing there on top is shielding the rest of the leaf from the sunlight, and more importantly, allowing those important chemicals to be reabsorbed by the tree. "
L43L2
"Listen to part of a lecture in a psychology class.For some time now, psychologists have been aware of an ability we all share.
It's the ability to sort of judge or estimate the numbers or relative quantities of things.
It's called the Approximate Number Sense, or ANS.
ANS is a very basic, innate ability.
It's what enables you to decide at a glance whether there're more apples than oranges on a shelf.
And studies have shown that even six-month-old infants are able to use this sense to some extent.
And if you think about it, you'll realize that it's an ability that some animals have as well.
Animals have number...uh...approximate...?
Approximate Number Sense. Sure.
Just think: would a bird choose to feed in a bush filled with berries or in a bush with half as many berries?
Well, the bush filled with berries I guess.
And the bird certainly doesn't count the berries.
The bird uses ANS: Approximate Number Sense.
And that ability is innate, it's inborn.
Now I'm not saying that old people have an equal skill or that the skill can't be improved, but it's present...uh...as I saicL.
It's present in six-month-old babies.
It isn't learned.
On the other hand, the ability to do symbolic or formal mathematics is not really what you would call universal.
You need training in the symbols and in the manipulation of those symbols to work out mathematical problems.
Even something as basic as counting has to be taught.
Formal mathematics is not something that little children can do naturally.
And it wasn't even part of human culture until a few thousand years ago.
Well, it might be interesting to ask the question:
Are these two abilities linked somehow? Are people who are good at approximating numbers also proficient in formal mathematics?
So to find out, researchers created an experiment designed to test ANS in 14-year-olds.
They had these teenagers sit in front of a computer screen.
They then flash a series of slides in front of them.
Now, these slides had varying numbers of yellow and blue dots on them.
One slide might have more blue dots than yellow dots, let's say...six yellow dots and nine blue dots.
The next slide might have more yellow dots than blue dots.
The slide would flash just for a fraction of a second.
So you know, there was no time to count the dots.
And then the subjects would press a button to indicate whether they thought there were more blue dots or yellow dots.
So the first thing that jumped out at the researchers when they looked at the result of the experiment was that between individuals, there were big differences in ANS proficiency.
Some subjects were consistently able to identify which group of dots was larger even if there was a small ratio, if the numbers were almost equal, like ten to nine.
Others had problems even when differences were relatively large, like twelve to eight.
Now, maybe you are asking whether some fourteen-year-olds are just faster, faster in general, not just in math.
It turns out: tha's not so.
We know this because the fourteen-year-olds had previously been tested in a few different areas.
For example, as eight-year-olds, they had been given a test of rapid color naming.
That's a test to see how fast they could identify different colors.
But the result didn't show a relationship with the results of the ANS test.
The ones who were great at rapidly naming colors when they were eight years old weren't necessarily good at the ANS test when they were fourteen.
And there was no relationship between ANS ability and skills like reading and word knowledge.
But among all the abilities tested over those years, there was one that correlated with the ANS results: math, symbolic math achievement.
And this answered the researchers' question.
They were able to correlate learned mathematical ability with ANS.
But it doesn't really tell us which came first.
Go on, Laura.
I mean, if someone's born with good approximate number sense, um, does that cause them to be good at math?
Or the other way around:
If a person develops math ability, you know, and really studies formal mathematics, does ANS somehow improve?
Those are very good questions, and I don't think they were answered in these experiments.
But...wait. ANS can improve?
Oh, that's right, you said that before.
Even though it's innate, it can improve.
So wouldn't it be important for teachers in grade schools to...
Teach ANS?
But shouldn't the questions Laura just posed be answered first?
Before we make teaching decisions based on the idea that having a good approximate number sense helps you learn formal mathematics. "
L43C2
"Listen to part of a conversation between a student and his theater professor.Hi. Professor Davis. Sorry I missed the class yesterday. I was just getting over a cold.
That's alright, Andrew. Feeling better now?
Oh, yeah, fine. Um, I had a question though.
For the mid-term, how much do we need to know like about the different acting styles?
Since the last few chapters have been on writing our own material, scripts and stuff...well...will the exam be about that? Or about stuff in the earlier chapters? Like.""um.""
Oh, Andrew. Before I forget, I will get to your question, but, now, don't leave without taking the tickets for tomorrow's field trip.
I have a last-minute meeting so I can't make it after all. But since you helped organize the trip, I'll let you hand out the tickets. I've got everything you need right here.
Sure, no problem.
And you don't need directions to the theater. You've been there before, right?
Yup.
Good. Oh, oh, also, please remind everyone about the reception afterward.
It'll be an opportunity to ask Alan Altman about his acting in the play, which we can discuss in class next week.
Ok, HI tell them. It's really something! I mean, I know our acting professors must in plays all the time, but it isn't every day you get to see one right here in town.
Oh, you might be surprised.
There's a calendar on the main bulletin board listing all the local productions that faculty are involved in.
Well, it seems like Professor Altman is a really popular actor. I just read his bio in the local paper.
I know the critics always praise him, but I had no idea he was such a commercial success, too.
And it said he just won an award last year for...uh...playwriting, wasn't it?
Well, there is a general playwriting category, but actually, his award was for script adaptation.
He adapted a novel into a play.
Script adaptation?
Oh, it's a very specialized skill.
Writing a play based on some other written work, novels, short stories.
Now we've been studying original plays, which are pretty much based on the writer's imagination.
But think about adapting a script...
Yeah, seems like it might be easier, like to start with something that's already written.
Well, actually think about it, transferring that material to a whole different genre, from narration to live dialogue.
Imagination is a part of it, sure, but it also requires a lot of technical knowledge of about theater production, acting and so on.
So Professor Altman, for example, he took a novel and made it into a play, dealing with all the different conventions that plays have.
You know, like limitations of scene changes and...uh...well, it'd be a good thing to ask him about it at the reception tomorrow.
Yeah, sounds like an interesting topic.
Oh, and before I forget, the packet with the tickets has a list of the students' addresses.
Since Ivan is picking you up first, you can direct the driver to the other students' dorms.
Sure. That was the plan.
Okay, good. Now, about the mid-term. "
L43L3
"Listen to part of the lecture in a children's literature class.Today we'll start looking at the most important children's book authors of the twentieth century.
And I'd like to start with an author illustrator whom some of you probably grew up reading:Dr. Seuss.
His actual name was Theodor Seuss Geisel.
Geisel's work was hugely popular among beginning readers and their parents, but it wasn't always considered literature or subjected to serious academic inquiry until relatively recently.
In fact, not only weren't his books considered literature, but they weren't always considered good school books.
In the late 1950s and even through the 60s, US teachers resisted Seuss's books because they perceived them as having a comic book style...fine, maybe, but not...not appropriate for the classroom.
None of Geisel's books individually won him a Pulitzer Prize.
And he didn't receive any top children's literary awards either.
Although the Pulitzer Prize committee did give him a citation in 1984 for his...uh...""special contribution over nearly half a century to the education and enjoyment of America's children and their parents.""
But again, that wasn't until 1984.
Perhaps one reason his books weren't taken seriously is that even though they often rhyme, you wouldn't call him a great poet.
Geisel's rhyme schemes are very simple.
And often, to make things rhyme, he used silly names for his imaginary creatures, like the Grinch and Sneetches.
In fact, one book features 34 pairs of rhymed words, but only eight of those pairs consist entirely of real words.
The rest are made-up words.
Geisel also illustrated his own books and created a lot of highly memorable characters from a visual standpoint.
Yet as far as his artistic talent, no one's ever called him a great artist or a great illustrator.
For his human characters, he pretty much drew the same face over and over.
Except for minor accessories, all the people in his books look the same.
Not exactly something you'd be encouraged to do in art school. And the way he drew even nonhuman characters was dismissed by many critics as being overly simplistic.
His landscapes, on the other hand, they are simple but they are also extremely clever.
He had this uncanny knack for creating the illusion of great distance with some very simple shapes and lines.
But what about from a pedagogical standpoint?
Well, let's consider Geisel's most famous book: The Cat in the Hat.
Now, in a way, this book, The Cat in the Hat, captures the essence of Geisel's particular genius as a children's author.
Geisel actually wrote it in response to an article written in 1954 by an acclaimed novelist named John Hersey.
In this article, Hersey criticized the textbooks being used in elementary schools to teach children to read.
He called the books 'boring, contrived, and utterly humorless'.
After seeing Hersey's article, Geisel must have wondered what made the books so dull.
And one thing he found was they use only words from the Dolch List.
The Dolch List contained a few hundred common sight words, words like, well, cat and hat.
At the time, the Dolch List was widely adhered to by publishers of textbooks for beginning readers.
Well, using only words from the Dolch List, Geisel tapped into his fertile imagination.
And the result was an incredibly funny and engaging storyline about a talking cat that convinces a brother and sister to let him make a huge mess in their house while their mother is away.
Another character, a talking fish, tries to warn the children that they'll be blamed for the cat's crazy antics.
You can really feel the tension building up in those kids as the cat makes the house messier and messier.
Ultimately the house gets straightened up in the nick of time.
And the kids are left speechless when their mom shows up and casually asks if anything interesting happened in her absence.
The kids, and presumably, Geisel's readers are left thinking: Should they tell the truth? And that's where the book ends.
Brilliant! There aren't too many authors who can set up a moral dilemma like this and then get children to think about it for themselves. "
L43L4
"Listen to part of a lecture in a physics class.The professor has been discussing electromagnetic waves.
So are there any questions before we continue our discussion of different types of electromagnetic waves?
Um, today, we'll focus on radio waves, and specifically, very low frequency radio waves. Yes, Tim.
Are you going to talk at all about the difference between radio waves and sound waves?
Uh, Ok. That might be a good place to start actually.
Sound waves are mechanical in nature, right? They can only originate and spread in places where there's some dense physical medium, like atmosphere or water.
They result from changes in pressure in that medium, like changes in air pressure.
So they can't travel through a vacuum, where there is no dense physical medium, which is why they can't travel through interplanetary space.
Radio waves, on the other hand, are fundamentally different from sound waves.
They are electromagnetic.
They result from oscillations of the electromagnetic field and don't need a physical medium, so they, like other types of electromagnetic wave, can travel basically anywhere, through a vacuum, or through atmosphere or water.
Now, radio waves can be detected.
For example, very low frequency radio waves can be detected with a special type of radio receiver called a very low frequency radio or VLF radio, which can pick up radio waves with very low frequencies, from 3 to 30 kilohertz, which aren't really picked up by a regular household or car radio.
So VLF radios pick up VLF radio waves and convert them to sounds we can hear.
Um, on Earth the main source of naturally occurring VLF emissions is lightning, which generates a pulse of radio waves every time it flashes.
Yes, Laura.
Since you almost always get lightning with thunderstorms. We can pick up VLF waves pretty often, right?
You just have to wait until there is a thunderstorm.
Ah, do you? Have to wait? VLF receivers are very sensitive and VLF waves travel very far.
So we can pick up emissions from lightning that's far away. So actually, you can pretty much listen to them all the time because lightning strikes Earth constantly, about a hundred times per second.
Even if there is no lightning where you are, with a VLF radio, you can hear the crackling from storms that are thousands of kilometers away.
However, some times of day are better than others for picking up VLF waves.
Daytime isn't as good as night time, for example.
And what's more, my colleague Denis Gallagher says, and in my opinion, he's right.
He says the best time to listen for them is around sunset or sunrise.
That's when there're natural waveguides in the local atmosphere.
Did you say waveguide?
Yes, a waveguide.
Usually it refers to a device, like a metal conductor that's used to guide and direct waves.
But waveguides also occur naturally.
They make a path for radio waves to follow in our atmosphere.
These natural waveguides occur when the Sun is rising or setting, which makes sunrise and sunset good times to pick up VLF emissions.
Now, there are a few different sounds that you can hear on a VLF receiver, because when lightning strikes the radio waves travel different distances and in different ways before they reach the receiver.
Some really interesting ones are called whistlers. Whistlers come from lightning-generated radio waves that leave earth's atmosphere and travel into earth's magnetosphere before bouncing back down.
Not all radio waves do this and the sound they make, well, we call them whistlers because they sound like slowly descending tones.
And no two whistlers are alike.
To me, they're the most intriguing.
Another interesting sound is the tweek.
Tweeks are the result of VLF waves that have travelled a long distance through the waveguides.
They produce a chirpy sound because the higher frequency parts of the wave reach the radio receiver before the lower frequency parts.
The entire wave is still considered very low frequency.
It's just that some parts of the wave have lower frequencies than others, OK? "
L44C1
"Listen to a conversation between a student and her sociology professor.I'm glad you got my message and were able to make it.
Where are the other members of your group? Tom and Jane?
They are actually at the library.
They have a biology lab assignment that's due later this afternoon. So I'm here to represent the whole group.
But...um...when we got your e-mail message about being worried about our research project, we were a little confused, we thought you were excited about our idea for the project.
Well, I think it's a great research topic, but when I looked closely at your plan for accomplishing the research, I realized that your group was probably asking for some trouble.
What do you mean? I thought that, you know, by monitoring students studying in the library we could really get a good understanding of people's study habits and stuff.
The thing is, I think you might have a problem because of the Hawthorne Effect.
The Hawthorne Effect?
The Hawthorne effect is a technical term for when researchers...uh...more or less forget about a specific variable, the variable of the researchers themselves.
Now, the students in the library, they are going to know that you are observing them, right? So you have to consider the effect your very presence will have on the people you are observing.
But...so you think... I mean it's not like our observations would be a secret. The students would know exactly what we would be doing.
I mean, we'd put up a sign right outside the library.
Yes, but that's just it.
When people know they are being watched, they act differently.
Let me explain how the Hawthorne effect got its name and...well...you,ll get the idea.
See, there was a manufacturing facility called the Hawthorne plant.
And researchers conducted some experiments there to see what conditions make workers the most productive.
What sort of conditions?
Well, one thing they experimented with was the lights. Were workers more productive with bright lights or dim lights? Well, here is the thing, whatever the researchers did, the workers' productivity increased.
When the lighting was improved , productivity went up.
When the lighting was dimmed , productivity went up again.
That doesn't make a lot of sense.
Exactly! So initially the experiment was considered a failure.
But then the researchers realized that their own presence had affected the workers' productivity.
The workers knew that the researchers were watching them , and with so much attention on them the workers felt compelled to work harder.
Oh, I guess that really could be an issue with my group's research.
Yes, but I don't want to send you all back to square one.
So how about you set up a meeting with your group members and discuss this. Then we can meet again and go over your ideas.
And I think that we should be able to figure out a way to get a round the problem. "
L44L1
"Listen to part of a lecture in a materials science class.Ok. Last time we finished going over some of the fundamental concepts of nanotechnology, the multi-disciplinary science of manipulating or controlling extremely small units of matter on the scale of molecules or even atoms.
So, I want to talk about how nanotechnology is being used today.
And just to give you an idea, we'll look at one particular application.
A team of material scientists in Massachusetts has been working on a new ultra-thin coating, a nano coating that might be applied to objects like bathroom mirrors, car windows, and eye glasses to prevent fogging.
And the coating has the potential to be a permanent solution, unlike the kinds of anti-fogging spray-on liquids that are on the market today.
Now, fogging often occurs when a cold surface comes into contact with warm moist air, such as when a glass shower door or mirror fogs up during a warm shower.
Now, what's actually happening is, what the fog is, is thousands of tiny spherical water droplets condensing on the surface of the glass.
Light hits the water droplets and is scattered in random directions, causing the fogging effect.
Now, the kind of spray-on treatments I mentioned.
Well, they wear off.
What happens is they cause the tiny water droplets to flatten when they condense on the surface of the shower door or bathroom mirror or whatever object it is, it's been applied to.
Because the droplets are flattened, when light hits them, the light doesn't scatter.
But, as I said, those kinds of treatments don't last very long.
The new coating has two important components.
One, negatively charged silicon nano particles, these are basically tiny particles of glass.
And two, a positively charged polymer, which you already know, a polymer is a chemical compound.
They're layered over each other.
The polymer, then the silicon nano particles, the polymer, then the silicon nano particles, you see.
They're layered in such a way that the silicon nano particles don't pack together tightly.
In other words, the structure has pores, or holes, little tiny pockets throughout it.
The coating prevents fog from developing, because it loves water.
It attracts the water droplets, sucking them into the tiny pores.
And that alters the shape of the droplets.
The droplets are forced to flatten and to join together into a single sheet of water, rather than remaining as single droplets, each of which is a sphere that scatters light in different directions.
Ok, so, instead of being scattered, the light passes through the thin sheet of water.
So, there's no fogging effect.
The ultra-thin coating can be made more durable by heating it, and of course the object it's applied to, to an extremely hot temperature, 500 degree Celsius.
What that does, is burn the polymer away, and fuse the silicon nano particles together, while maintaining the structure of pores.
But that's possible only on materials that can withstand high heat.
Glass? Yes. Plastics? No.
But they're working on solving that problem, trying to come up with a way to coat plastics and other materials, durably and effectively.
Interestingly, it was a plant, the lotus plant that inspired this work.
I guess you could say inspired it in an indirect sort of way.
The leaves of this plant are what we call superhydrophobic.
Lotus leaves, being superhydrophobic, don't attract water.
They repel it, in a big way.
When raindrops fall on lotus leaves, they remain spherical. They roll right off.
So for a long time, the Massachusetts scientists tried to create a coating that acted like these lotus leaves, a coating that was superhydrophobic.
But then they began to think about the opposite extreme.
Could they accomplish their goal by making a coating that, instead of repelling water, actually, attracted water?
Well, they seem to have gotten quite far with this approach.
It's really strong work, with a range of interesting consumer applications.
It's not costly to manufacture the coating.
Some carmakersare interested in applying it to their wind shields.
Looks like we'll probably see it on the markets in everyday products in the next few years. "
L44L2
"Listen to part of a lecture in an introduction to drama class.Now, throughout the history of drama, there has been a, well, a relationship between the structure of a play, and the structure of the space where the play was performed.
And this goes all the way back to the ancient Greeks.
The Greeks built the first theaters in the fifth century B.C.E.
These were outdoor theaters.
The architects looked for sites where you had a natural bowl-like formation on the side of a hill, and that's where they set the theater.
All Greek theaters were pretty much the same.
There was some natural variation to accommodate the size and shape of the site, but as far as the basic elements went, those remained constant.
Have a look at this diagram.
Let's start with the area where the actors performed, like, what we call the stage today.
The Greeks referred to this space as the skene.
Uh, there's some confusion about the use of the word 'skene' by different scholars.
Some authors use it to refer only to the structure behind the stage, while others use it to refer to the structure and the stage together, and that's how I'll use the term, to refer to both the stage and the building.
Um, so, anyway, the skene started as a simple wooden platform, but eventually became much more elaborate.
The front wall of the building was decorated like a palace, or a temple, and served as background scenery for the play.
The building was also a storage place for costumes, props, things like that.
Yes, Robert?
So, did they decorate the skene for each play or, um, change the scenery during the play, like we do today?
Or, did the whole story take place in one setting?
Well, everything the audience saw happened in that one setting usually in front of either a temple or a palace, but the audience didn't witness all events in the story.
Some events couldn't be presented convincingly, so the playwrights had them take place somewhere off stage, where the audience couldn't see them.
And then news of the event would be reported by one of the characters. Diane?
Last summer, I saw... Hippolytus.
Excellent! I hope you enjoyed it.
Definitely. So, at one point, you see Hippolytus being sent off by his father, then a little later, a messenger arrives and describes how Hippolytus was riding in his chariot when a giant bull appeared out of the ocean, and caused the chariot to crash, and then, after we hear what happened to Hippolytus, he's carried back on stage where he dies.
Exactly. I mean, can you imagine trying to show all that action, a giant animal rising out of the sea?
Um; Okay. The next area was the space the ancient Greeks called the Orchestra.
The orchestra was either round, as you see here, or a semi-circle.
Um; in ancient Greek, the word orchestra actually meant the dancing place, because this is where the chorus danced and sang.
But to understand Greek plays, you need to understand an additional function of the chorus.
Yes, the ancient Greek chorus did most definitely sing and dance like choruses do today, but the chorus's most important role was commenting on what the characters on stage were doing and thinking.
In fact, Aristotle, the Greek philosopher, thought the chorus should be considered as acting out a role in the play.
Yeah, I read that a chorus could have a distinct personality, just like a person.
Absolutely. In fact, you'll see an excellent example of that in the first play we'll be studying.
Okay, the last space was the seating area for the audience.
This was called the theatron.
In ancient Greek, theatron means seeing, that's S-E-E-l-N-G, seeing place.The theatron was shaped in a semi-circle with rows of seating rising up the sides of the bowl.
It was designed to take advantage of the natural acoustic benefits of the setting.
The shape of the bowl captured sound and funneled it upwards so that even in the top rows, spectators were able to hear the performers very clearly.
Actually, that the name theatron means seeing place is kind of ironic.
Some theaters had fifty or more rows of seats accommodating up to 14,000 spectators, ascending way up the hillside, and this was long before theater binoculars were invented. "
L44C2
"Listen to a conversation between a student and an art professor.Hi. Dr. Morten. I'm Karen Stern. I met you briefly about a year ago when I was applying to the university.
You were on a panel of professors and you were talking about the art department.
Ah...and you are now a student here.
I guess I said the right thing.
Yeah. Right now I am doing the intro-courses in the art department, but I am really interested in painting.
Well, I teach several of the painting courses so I hope to see you in the future.
Actually I was wondering: you are in charge of student art exhibitions at the university gallery, right?
Right!
So I know all the exhibitors are students, but I was wondering how you choose the works you exhibit every month. Is there like a submission process or something?
Now, there is a submission process, yes.
We a have gallery review committee, but we already have our exhibitions planned for the rest of the schoolyear.
Generally our exhibitors are third- and fourth-year students, well into their coursework.
Oh; Well, I guess that will be something to look forward to then.
Tell me, do you show all kinds of paintings?
Well, actually we started doing something different with the gallery this year.
We are featuring a specific technique each month.
Next month's exhibition, for instance, will feature drip paintings.
Really? Like Jackson Pollock?
Ah....so you are familiar with Pollock's work.
Well, sort of, though I've only seen photographs of it.
I know he dripped paint onto the canvas instead of using a brush.
I read he stretched out his canvases on the floor of a studio and then he climbed up on a ladder to pour paint, ordinary house paint, from a can onto the canvas.
That's right. That was characteristic of Pollock in the late forties, in what we call his drip period.
And the object was to produce a constant stream of paint to create continuous lines, because as you know when you use a brush directly on a canvas you get broken lines.
So, you like Pollock.
Yeah, I do. I like abstract works in general.
There's a class on abstract art, right?
Actually I teach that class and drip painting was one of our themes last year.
Some students from last year's class have continued experimenting with it and created some incredible pieces using everything from squeezed bottles to computer controlled sprayers.
Do they look a lot like Pollock's work?
Well, our goal wasn't to imitate Jackson Pollock.
The object was to get students to look at different ways of applying paint to a canvas.
But you don't have to enroll in a specific course to be invited to exhibit your work.
It just has to fit the theme for one of our exhibitions. "
L44L3
"Listen to part of a lecture in an anthropology class.So, we've been talking about early civilizations, how they developed, and early agriculture.
And it's believed that agriculture arose independently in a few areas of the world about ten thousand years ago, and then spread from those areas to the rest of the world.
Those cradles of agriculture include the Middle East, China and Southeast Asia, and parts of the Americas.
Now, for many years archaeologists have speculated that agriculture also arose independently in another center, too-New Guinea, which is just north of Australia, in the South Pacific Ocean.
You can see it on this map.
So, it had been assumed for a long time that New Guinea,
that domesticated plants and animals,
the practice of agriculture, generally,
had been introduced from Southeast Asia about 3500 years ago,
had come south essentially.
Then in the 1960s and 70s, research was conducted at sites in New Guinea to explore the possibility of independent agricultural development.
But unfortunately, the evidence gathered at that time was inconclusive.
For instance, although evidence was found of deforestation,
you know, cutting down trees, from at least 7,000 years ago,
that is long before we;d thought previously.
It was unclear whether the forest had been cleared by farmers to plant fields,
or by hunter-gatherers, so they could hunt more easily.
And many plant remains like seeds and fruits don't preserve well in swampy soils, in humid environments like you often find in New Guinea.
So really, the proof was limited.
But, recent research has turned up some pretty convincing support.
A group of archaeologists returned to a site that had been previously examined,
Kuk Swamp, which is in a mountain valley in the highlands of what is now Papua, New Guinea.
Based on their findings, they identified a succession of phases of agricultural development in the wetlands there,
with several of these phases predating the earliest known agricultural influence from Southeast Asia.
At the site in Kuk, they used an array of modern archaeological methods to analyze sediment samples from the soil.
From the oldest soil layer dating back 10,000 years, they found evidence of pits, stake holes and ditches.
Now, these all indicate that crops were being planted.
Plants are tied to stakes, and ditches are for... for drainage,
a proof of a very early, first phase of agricultural development.
The second phase, which they identify from a higher layer of soil, featured regularly distributed mounds.
Mounds were constructed to plant crops that can't tolerate very wet soil,
such as bananas, because remember Kuk is a swampy wetland, and bananas wouldn't ordinarily grow well there.
And in the layers from Kuk's third phase, they found evidence of an extensive network of ditches and drainage channels,
indicating a further refinement of wetland cultivation.
Because they had more advanced techniques than were available to earlier researchers,
the archaeologists also were able to identify actual plant remains - micro-fossils in the soil from banana plants,
and...and also grains of starch from taro, on the edges of stone tools that date from about 10,000 years ago.
Finding the taro remains were very important,
because it meant that it must have been planted there, brought from the lowlands,
because taro doesn't grow naturally in the highlands.
And as for the bananas, researchers also found a high percentage of fossils from banana plants in sediment samples dating from about 7,000 years ago,
proof the bananas were deliberately planted,
because where bananas grow naturally the concentration of the plant fossils is lower.
Bananas don't naturally grow so densely.
As a matter of fact, recent genetic research,
genetic comparisons of banana species,
suggests that the type of banana grown in New Guinea was domesticated there and then brought to Southeast Asia.
So, not sure where I'm going with this?
Well, usually, we expect to see that certain social changes are brought about by the development of agriculture,
structural changes in the society like rapid population growth, different social classes.
But New Guinea, it's largely unchanged.
It's remained an egalitarian and rural society, so what does that tell us about the usual assumption? "
L44L4
"Listen to part of a lecture in an environmental science class.Now, there is growing interest these days in generating electricity from renewable energy sources, right? From developing wind farms to tapping into an underground source of geothermal energy.
And when you're considering a new project, it's important to look at the costs as well as benefits of developing that energy source.
Let me give you an example of the kind of thing I am talking about.
There is currently a lot of interest in harnessing the power of the oceans,
of the ocean tides, that is,
the movement of huge amounts of water which causes the water level of oceans to rise and fall.
The idea is that if we can harness that tidal energy,
it'd be a great clean renewable energy source.
One place where this tidal energy can be harnessed is at a shallow body of water, such as an estuary.
Now, can anyone tell us what an estuary is? Yes, Ted.
An estuary is where a river enters the ocean.
The fresh water meets the ocean water.
Sometimes it is covered in water. Sometimes it is not.
Some parts of the estuary, as the tides go in and out, but other parts are always submerged.
Now, estuaries are an ideal place to try to capture energy from changes in tides because,
well, there is an exceptionally large difference between the water level at high tide and at low tide.
All that movement of water generates a lot of energy.
And one way to harness that energy is by building a structure called a barrage there.
A barrage is basically a large low dam that's built across an estuary.
When the tides go in and out, the moving water flows through tunnels in the barrage.
So you have huge amounts of water trying to flow through these relatively small tunnels and that turns turbines that generate electricity.
Now, these estuaries are important because of their high level of biological productivity.
They are home to lots of birds, fish and other marine life.
So when you propose to construct a barrage, you have lots of issues to consider.
For example, it would change the existing water levels in the estuary.
Since a lot of water is getting held up by the barrage, the incoming tides won't go as high,
but they wouldn't be as low during low tide, either.
This might help prevent flooding. But it would also affect the mudflats, those areas of mud that normally are exposed when the tide recedes.
But don't lots of birds rely on exposed mudflats for food?
I mean, don't they eat tiny animals that live in the mud?
And what about those tiny animals?
What would happen to them if the mudflats were endangered?
So you are seeing some of the potential problems with the barrage.
But consider this, right now, the water in an estuary is very cloudy.
The tidal currents are constantly churning up the sediments that rivers deposit in the estuary.
But a barrage would reduce the tidal currents. So a lot of that sediment would settle to the floor of the estuary.
It wouldn't get stirred up so much.
The water would be clearer,
allowing more sunlight to reach deeper into the water,
which might lead to more food for birds and other animals,
attracting new wildlife to the area.
So it;s a complicated environmental picture.
Have they tried this anywhere? Built a barrage?
Yes, there are several in operation. There is one in France.
Now, they have to be careful there about how they turn on the turbines because they create currents and waves that can affect boats.
But I haven't read about any major ecological problems.
In fact, the fishing is supposed to have improved.
Plus there is even more bird life.
But some of the barrages we're considering now would be much larger than that one.
There has been one proposed for the estuary of Great Britain's Severn River, one of the largest estuaries in the world.
It would be 16 kilometers long.
Just to give you an idea, the barrage in France is less than a kilometer.
Outside of environmental concerns, such a project would be hugely expensive and that's another argument against barrages,
well, such large ones anyway.
Critics say that it would better to use that money for something else,
such as improving the energy efficiency of buildings.
You could make a lot of buildings more efficient with all that money and that would reduce the need for electricity. "
L45C1
"Sorry you had to wait. It's a busy time of year.Lots of people mailing packages home.
I bet. I'll have to come next week to do that. I'm moving out of my dorm and I'm sending some papers home.
Ok. We'll be here. What can I do for you today?
Well, my roommate asked me to pick something up for her. I told her I was coming down here. She got this notice saying that there's a package to pick up. I guess it was too big to fit into our mailbox.
I am sorry. But I can only give packages to the person who they're addressed to. It's university policy.
Really? Could you make an exception? She is my roommate.
I wish I could, but she'll have to come and get it herself.
And be sure to tell her to have her student ID card on her.
We'll need to see identification.
Oh, and she'll need that package notification too.
Ok. I'll let her know. Also since I'm moving, I'll be able to receive my mail at my new apartment, so I don't really need my campus mailbox.
Oh, Ok. Although I should tell you that we do recommend that students use the campus mailbox service even if they are moving off campus.
Really? Why?
Well, if any of your professors want to notify you of changes to class schedules or get in touch with you for any reason...
My professors have my email address.
Yes, that's true. But remember things like university newsletters, flyers from university clubs, notices about special events, they're only distributed to campus mailboxes.
None of that is mailed off campus.
Well, I worked at the college newspapers, so I should be able to keep on top of what's going on.
Plus there's a bulletin board outside the dining hall.
True. But you know if it's the campus mailbox fee, I might be able to offer you a less expensive rate for next year.
We can do that in special circumstances.
Thanks.But I mean I can afford the mailbox fee. It's just that between my off-campus address, my email account and the school newspaper, I don't think there will be a problem.
Ok. In that case, stop by the main desk on your way out of the building and pick up the form you'll need.
And don't forget to include a forwarding mail address for anything that's addressed to your box from outside the university. "
L45L1
"Listen to part of a lecture in an Art History class.As I was saying, the Renaissance period, which started in the 1400s in Europe, the Renaissance was still a pretty religious period, and that's reflected in the artwork of that time.
But artists were starting to experiment with a more secular point of view as well, a tendency to also use the natural world as the subject matter for their art.
And there were different ways that these natural themes were explored.
For instance, many artists would paint portraits, while others, although this was more common in Northern Europe, would make landscapes the subject of their works.
But today i like to consider an influential Italian Renaissance artist, Leon Battista Alberti, who took a slightly different approach.
Leon Battista Alberti was a painter, sculptor, architect, musician, poet, very wide-ranging interests, like Da Vinci or Michelangelo, the sort of guy for whom the term ""Renaissance Man was in fact created.
created. Alberti believed that the most important approach for a painter was to capture a story or narrative.
Now, as I've indicated, this narrative could be the religious or secular, depending on what the work of art was for.
If the work was to be placed in a church, then obviously, it'd have a religious theme, whereas, if it was for someone's home, then it could deal with a different subject matter.
The exact narrative didn't really matter, so long as it was one that captivated the audience, that held the viewers' attention.
So, what is actually needed to tell a story?
Well, Alberti needed characters, right?
Human figures. And he wanted to represent them as realistically as possible, to capture the viewers' attention.
One way he achieved this was to make use of what's known as ""the contrapposto pose"".
A contrapposto pose basically entails showing a slight twist in the body.
The shoulders and hips are usually bent in different directions.
In other words, if the left shoulder is bent, so that it's slightly higher than the right shoulder, then the hips will be bent, so that the left side will be slightly lower than the right side.
Similarly, in sculptures, most of the weight seems to be on one foot, which also results in this slanted position, making it seem like the figure is about to walk or move. This adds to the realistic aspect of the figure.
But there are actually a lot of things that could go wrong in the attempt to create such a pose.
You could make a figure's arms bigger than its legs, or the head too small for the body.
Messing up the proportions can leave a figure looking cartoon-like and unnatural.
But Alberti had a solution.
He encouraged artists to visualize a figures' bones and structure.
This would give the artist an idea of the proportions of the figure.
From there, Alberti suggested that the artists imagine attaching the tendons and muscles, then covering those with flesh and skin.
Now, although this method may seem complicated, artists since antiquity have used anatomical observations to try to get the proportions of the human figure as accurate as possible, though obviously not to the degree that Alberti was recommending.
Now, in addition to characters, the setting is extremely important, especially when attempting to tell a story realistically.
Renaissance artists essentially needed to create a three dimensional scene on a two-dimensional surface.
They accomplished this by the use of perspective, a relatively new idea for artists at the time.
In particular, the type of perspective that Alberti advocated was called Linear ""One-point Perspective"".
In fact, Alberti was one of the artists who developed the geometry behind linear one-point perspective.
Linear perspective basically consists of drawing straight lines that extend from the forefront of the painting into the background, lines that seem to be paralleled to each other, but which actually converge on a single point in the horizon, called the vanishing point.
By drawing figures and objects smaller and smaller, as the lines get closer together, the artist is able to create depth in a painting.
This gives the illusion of a third dimension, and makes the work of art more realistic. "
L45L2
"Listen to part of a lecture in a biology class.So that's the overview of the human immune system.
But we have a few minutes left.
Any questions? George?
Yes. You talked about T-cells, naive T-cells.
Can you go over that part again? And also why do we call them that anyway?
All right. They're...they're known as T-cells because they develop in the thymus.
The what?
Thymus.
That's T-H-Y-M-U-S.
It's a small organ in the body.
Anyway, that's why we call them that. They come from the thymus.
And T-cells are a part of the body's immune system.
They can recognize and eliminate cells from outside the body that might cause disease.
But why naive?
I mean, we might call people naive if they don't have enough experience to know about the dangers of the world.
But how can you call a cell naive?
Well...when this type of immune cell encounters a cell from outside the body, like maybe a bacterium.
It interacts with that bacterium and learns to recognize it.
So whenever the immune cell runs into that kind of bacterium in the future, it'll attack and kill it.
At that point we call it a memory T-cell because it's learned to recognize a protein marker that identifies this particular kind of bacterium.
But before it's learned to recognize any particular protein from outside the body, we call it naive. Okay?
Yeah, I get it.
There is a lot of biochemistry involved that we'll get into in the next lecture.
But your question reminds me about a study that some of my colleagues are doing.
It relates to caloric restriction.
Caloric? Like calories in the food we eat.
Exactly! We are talking about the sugars, carbohydrates, fats that our bodies burn to get energy which we measure in calories.
Okay, let's back up a little.
Back in the 1930s, a nutritionist at Cornell University put mice on a severely restricted diet.
He gave each mouse in one group thirty percent less food, or more precisely, thirty percent fewer calories than the mice in the other group which ate a normal amount.
And the result, the underfed mice lived much longer than the normally fed ones.
Wow! Does that just go for mice?
Apparently not.
Similar results have come from experiments on other animals from roundworms to most recently Rhesus monkeys.
These monkeys, two groups of them, were given all the vitamins and minerals and other nutrients they needed, except that one group got thirty percent fewer calories.
And now after thirty years or so, about an average lifetime for a monkey, it's clear that the monkeys that have been on the calorie restricted diet are doing a lot better than the ones on that we consider a normal healthful diet.
Like in terms of blood pressure and lots of other measures, the calorie restricted monkeys are much healthier and they just look and act younger than the monkeys in the normal diet group.
And as a group, they are living longer.
Interesting. But what's the connection?
Oh, with the immune system?
Well, it is been shown that the immune system becomes much less effective as animals age.
That's true in humans too.
We think those naive T-cells just get used up.
I mean it is not like the body's always making lots of new ones.
And over the course of a lifetime, as T-cells encounter more and more strange bacteria or whatever, the naive T-cells get turned into memory T-cells.
So later on in life, there are fewer and fewer of these naive T-cells left to deal with any new diseasecausing organisms that might attack, which means less immunity, and the animal or person is more likely to get sick.
But caloric restriction, it kind of shocks the system, and one result is, well, those monkeys on the calorie-restricted diet had lots more naive T-cells left than you'd expect in monkeys that old.
The expected drop in naive T-cells, apparently the shock of getting thirty percent fewer calories really slows that down.
And after many years, with so many more naive T-cells still in reserve, these monkeys are a lot better at fighting off new infections than normally fed monkeys of the same advanced age.
And that's why they live longer?
Well, it's got be one reason.
This is all pretty complex though with lots of details yet to be worked out.
But are results the same for humans?
Hard to say.
A good study would take decades. And it's not easy finding people who'd want to take part, would you?
And eat thirty percent less.
That would be tough.
You bet it would. "
L45C2
"Listen to a conversation between a student and her economics professor.Excellent presentation you made at the end of class yesterday.
Oh, thanks.
Im so glad you volunteered to present first.Starting out by outlining what you were going to say, then at the end summarizing the key points. It was a very effective way of getting your points across.
I'm glad you think so. I was afraid it might come across as too formal.
Not at all. In fact, I think it's a great approach in general for these presentations.
So I hope the others were taking note, and the economic model you discussed: build operate transfer. I think everyone was quite interested.
Yeah. It makes so much sense.
If governments allow private companies to build public works like a power plant and then operate it for a decade or two before transferring ownership to the government, everyone benefits.
Yes, the private companies make a profit.
The public gets immediate infrastructure.
And all without the government having to spend any money upfront, which is amazing.
Right.
Anyway as I said in my presentation, this model is being used in Turkey right now and you said when you handed out that brochure in class last week, about the university's global enrichment initiative.
You said one of the countries involves in that is Turkey.
Yes, that's right.
So I wanted to see if there's a chance the university sends fifteen students overseas to study?
Fifteen students per country, fifteen for Turkey, fifteen for Brazil, fifteen for Russia.
We've got a total of six countries participating next summer.
Oh!
Yeah.
And you spend six weeks in whichever country you are selected for. The classroom component consists of seminars on that country's culture, politics and economy.
Most sessions are taught in English by local professors.
But two of our faculty accompany each group and also give seminars.
I'll be going to Brazil to teach a seminar on coffee next summer.
But you're an economist.
Coffee's played a central role in Brazil's economic development for over 200 years.
About a third of the coffee consumed worldwide is produced in Brazil.
Oh I had no idea.
Hmm...So if I applied, I mean, can students pick the country they want to go to 'cause if I could go to Turkey...
Well, the primary goal of the Global Enrichment Initiative is simply cultural exchange.
So students who've never been overseas before can broaden their perspective.
This is why on the application you are asked to indicate your first, second and third choice countries.
I'm only interested in Turkey, though. I'm studying both Turkish and Turkish history this term.
I see.
And maybe I could learn more about how they're implementing the build operate transfer model there.
Plus, I wouldn't want to take a spot away from someone who really wanted to go to one of the other countries.
Well. I guess you could leave the second and third choices blank. "
L45L3
"Listen to part of the lecture in a chemistry class.So just to sum up, matter is anything that has mass and volume, right?
Anything that takes up space. And this includes solids, liquids and gases.
And if we combine two portions of matter, we get a mixture.
Now, there are two main kinds of mixtures: homogeneous and heterogeneous.
Maybe I should put this on the board.
Whether a mixture is homogeneous or heterogeneous...
well... this relates to the notion of phase.
Remember we defined the word 'phase' as being one physical state, whether solid, liquid or gas, that...
well... that has distinct boundaries and uniform properties.
So homogeneous mixtures... What are they?
Okay. The prefix 'homo-' means 'same'.So a homogeneous mixture is the same throughout.
It contains only one phase.
So if you put alcohol in water, the two liquids combine.
They disperse into each other.
And you can't perceive any boundary between the two any longer.
So the mixture contains only one phase. Even though two phases went into it, it now contains one phase and we can't detect any boundary between the water and the alcohol once they're mixed together.
The two portions combined form a single phase.
Now, if homogeneous mixtures are ones that are the same throughout, then what do you suppose heterogeneous mixtures are?
Right. Mixtures that are different throughout.
If you mix oil and water together, the mixture contains two liquid phases because the oil will float on top of the water because of the oil's lower density.
They are not going to mix together like alcohol and water do.
You can see the boundary between them and in fact, they are mechanically separable.
The same is true for soil, which is a mixture of solid materials.
So if you look closely at a sample of soil, you are going to see bits of sand, some black matter, maybe even pieces of vegetation.
Since you can see all the different components, detect distinct boundaries, we've got multiple phases.
And in fact, you can pick out the components. The various portions can be mechanically separated.
Now, with some heterogeneous mixtures, you can see the different phases with the naked eye.
But that's not so for all of them, like smoke.
Actually, that's a good example because to the naked eye it looks uniform, like it's a single phase.
But if you magnify it, you can see that there are tiny solid and liquid particles suspended in the air.
So actually what you got in smoke are three phases: solid, liquid and gas, which you can separate by a process of filtration.
Another example, uh, dirty water. Okay? Dirty water is water that has suspended solid matter in it.
That can be filtered too.
Pass it through a filter and the dirt and whatever else is in there will stay behind in the filter paper.
And the clean water will pass through it.
Again, depending on the size of the particles in the water, you might need magnification to see them.
But even so, they can be detected. The boundaries are detectable. So multiple phases, okay?
Homogeneous mixtures, on the other hand, well, no amount of magnification could reveal a detectable boundary between the components.
Their mixing extends all the way to the fundamental particle level.
And we use the term ,solution, to refer to the single phase, homogeneous mixtures.
When salts dissolve in water, no amount of magnification is going to show you separate pieces of salt.
There are no detectable boundaries between salt and water.
So it's a solution.
Even so, what you can do with solutions is separate the parts by a process called distillation.
If you distill salt water, water gets boiled away from the solution and only the salt remains behind.
And in your next lab actually, we'll be using these processes, distillation and filtration, to show how we can separate the different parts of some mixtures.
Now, there are other ways that we can describe mixtures.
And one of these is by properties, uh, variable properties.
A real simple example of this is the taste and color of a cup of coffee.
The more coffee that's dissolved in the water, the stronger the taste of the coffee, and the darker the color, the darker the solution.
So, color and taste, these are two variable properties.
And these variable properties, they vary of course, because of the relative amounts of the components, and the melting or freezing points of liquids too.
A solution of salt water, for example, will have a different freezing point depending on how much salt is dissolved in the water. "
L45L4
"Listen to part of a lecture in an anthropology class.OK, today we are going to be moving on, and we're going to be talking about early portary.
But rather than me just giving you a broad overview of how pots or ceramic vessels were developed and used in different regions of the world, we're gonna consider a specific example, a case study. And we're going to focus on ceramic cooking vessels from just one part of the world.
So the question I want to look at today concerns the use of ceramic cooking vessels, clay pots, in the Arctic during ancient times.
Why were they developed and used there?
So, to begin with, we don't know for sure when human beings first started creating pottery, but we have evidence of it from over 15,000 years ago.
And in the Arctic, ceramic cooking pots didn't appear there until some 2,500 years ago.
Now, it's not surprising that they appeared relatively late there.
In fact, what's been something of a mystery is why they were used at all, in the Arctic, I mean.
Ken?
Why wouldn't they use pottery?
Good question. What would some of the drawbacks of ceramic containers be for ancient people groups in the Arctic?
Ancient Arctic societies were nomadic, right?
I get it! Clay pots are fragile.
So if people were moving around all the time, well, the pots would probably keep breaking.
Precisely. Ceramic cooking vessels can't be transported easily.
That's one thing.
And think of how ceramics are produced.
You need water and clay of course.
You need to make the pot, allow it to dry for a long time.
Warm, dry locations work best for this of course.
And then you need to fire it, bake it. So you can see the role that climate would play in whether or not ancient people created and used ceramic cooking pots.
And that's why manufacturing pottery would have been a challenge, actually quite difficult for people in the Arctic.
But you're saying they did make ceramic cooking pots.
Yes. So the question is, given all these clear disadvantages, why would Arctic people choose to make and use ceramic cooking vessels? Sue?
I read somewhere that by cooking food in clay pots, people increase the ... well, they made food easier to digest, something about making the nutritional components of foods more accessible?
That's definitely true as far as many nutrients are concerned, but some nutrients, like vitamin C, are destroyed by cooking.
But the ancient Arctic people ate a diet that consisted almost entirely of raw or only minimally cooked meat and fish or shellfish.
I saw something on television once, a documentary that talked about how healthy the diet was, how it provided all of the nutrients they needed.
I guess that would include vitamin C as well, but then what I don't understand is: why would they have cooked their food at all?
Ah, here's where we need to look beyond obvious factors and consider things like culinary preferences.
Although the diet of ancient Arctic people mainly consisted of raw and minimally cooked food, it was carefully prepared.
It was based on an interplay of contrasts, um, different temperatures, or hard and soft textures.
Sometimes meat was only partially defrosted.
For example, one way of preparing meat was to boil it briefly, leaving the center frozen.
So cooked food, or partially cooked food, for ancient Arctic people, was a matter of social preference.
So again, the question is - why did they use ceramic pots to cook their food?
That's not the only way to cook food. And we've already looked at some disadvantages of ceramic pots.
So why use them?
Well, first of all, wood for cooking fires was in short supply.
And because of the extreme climate, food had to be prepared inside, indoors most of the year.
Therefore, fires had to be small, and cooking methods had to be efficient.
So in regions of the Arctic where wood was scarce, and where the houses could not withstand large fires and did not have good ventilation, we do find advantages associated with ceramic pots. "
L46C1
"Listen to a conversation between a student and an employee in the student housing office.Hi. I'm a first-year student here. I, I live in the dorms, and I, well, I like where I'm living now. It's convenient and quiet, but I'm starting to think about where I wanna live next year.
Good idea.As a second-year, you have more freedom to choose a place that suits your needs.
Yeah! And I want to make sure that, well, that I apply in time to get what I want.
And, um, a friend was telling me about these common-interest houses on campus.
Yes. We have a language house, a life science house, a music house...
Yeah, the music house, that's the one I'm interested in.
But, um, I' m not a music major.
I do play an instrument, but I'm a history major.
Oh, that's not an issue.
You see, that house isn't just for music majors. It's for anyone who's interested in music.
But isn't that everyone?
Well, maybe. But the house has a performance area and practice rooms.
So people who choose to live there need to be open to the possibility that there's always gonna be someone playing something,
An instrument, the radio, even at odd times. You'll pretty much always gonna hear music there.
That might bother some people.
Doesn't bother me. And I'd love to have a place to practice my saxophone without worrying about disturbing people.
Well, it does sound like it might be a good fit for you.
And the house also functions as a social club.
I know they do activities, but I don't know much beyond that.
Well, for example, every month, I think it is, there's an informal concert.
Any house resident can perform. And remember that big jazz festival at University Park last month?
Of course. It was amazing.
The music was great. Um, I, I didn't connect it to the music house.
Not many people do.
Anyway, they put on a whole range of other activities as well.
Someone at the house could give you more information about those.
So, how do I...um, what's the process for getting a room there?
You need to fill out an application form and send it to the house director.
The form's on the housing department's website. But, don't get your hopes up too high.
They can only accept about 30% of students who apply.
Oh, wow, I had no idea.
So, for your application, it needs to include a personal statement,
you know, why you're interested in living in the house, how you might contribute to the group. There are guidelines on the form.
That statement's really important, because it's basically how they decide who to accept into the house. "
L46L1
"Listen to part of a lecture in a biology class.I'd like to continue our discussion of animal behavior, and start off today's class by focusing on a concept we haven't yet touched upon: swarm intelligence.
Swarm intelligence is a collective behavior that emerges from a group of animals like a colony of termites, a school of fish, or a flock of birds.
Let's first consider the principles behind swarm intelligence and we'll use the ant as our model.
Now, an ant on its own is not that smart. When you have a group of ants, however, there you have efficiency in action.
You see, there is no leader running an ant colony. Each individual, each individual ant operates by instinctively following a simple set of rules when foraging for food.
Rule number one: deposit a chemical marker called a pheromone.
And rule two: follow the strongest pheromone path.
The strongest pheromone path is advantageous to ants seeking food.
So for example, when ants leave the nest, they deposit a pheromone trail along the route they take.
If they find food, they return to the nest on the same path,
and the pheromone trail gets stronger.
It's doubled in strength.
Because an ant that took a shorter path returns first, its pheromone trail is stronger and other ants will follow it according to rule two.
And as more ants travel that path the pheromone trail gets even stronger.
So what's happening here?
Each ant follows two very basic rules.
And each ant acts on information it finds in its immediate local environment.
And it's i mportant to note, even though none of the individual ants is aware of the bigger plan,
they collectively choose the shortest path between the nest and the food source,
because it's the most reinforced path.
By the way, a few of you have asked me about the relevance of what we are studying to everyday life.
And swarm intelligence offers several good examples of how concepts in biology can be applied to other fields.
Well, businesses have been able to use this approach of following simple rules when designing complex systems.
For instance, in telephone networks,
when a call is placed from one city to another,
it has to connect through a number of nodes along the way.
At each point, a decision has to be made:which direction does the call go from here?
Well, a computer program was developed to answer this question based on rules that are similar to the ones that ants use to find food. Remember, individual ants deposit pheromones and they follow the path that is most reinforced.
Now, in the phone network,
a computer monitors the connection speed of each path and identifies the paths that are currently the fastest, the least crowded parts of the network.
And this information, converted into a numeric code, is deposited at the network nodes.
This reinforces the paths that are least crowded at the moment.
The rule the telephone network follows is to always select the path that is most reinforced. So similar to the ant's behavior,
at each intermediate node, the call follows the path that is most reinforced.
This leads to an outcome which is beneficial to the network as a whole and calls get through faster.
But getting back to animal behavior,
another example of swarm intelligence is the way flocks of birds are able to fly together so cohesively.
How do they coordinate their movements and know where they're supposed to be?
Well, it basically boils down to three rules that each bird seems to follow.
Rule one:stay close to nearby birds.
Rule two:avoid collision with nearby birds.
And rule three:move in the average speed and direction of nearby birds.
Oh, and by the way, if you're wondering how this approach can be of practical use for humans,
the movie industry's been trying create computer-generated flocks of birds in movie scenes.
The question was:how to do it easily on a large scale?
A researcher used these three rules in a computer graphics program, and it worked.
There have also been attempts to create computer-generated crowds of people using this bird flocking model of swarm intelligence.
However, I'm not surprised that more research is needed.
The three rules I mentioned might be great for bird simulations, but they don't take into account the complexity and unpredictability of human behavior.
So, if you want to create crowds of people in a realistic way,
that computer model might be too limited. "
L46L2
"Listen to part of a lecture in an art history class.As you know, portrait artists often position their subjects so that their head is turned a little to one side,
thereby presenting the artist with a semi-side view, a semi-profile view.
And for some reason, western European artists have historically tended to show the left side of the subject's face, more than the right.
A while back, some researchers examine about 1,500 portraits painted from the 16th to the 20th century in Western Europe.
And in the majority of them is the left side of the face that's most prominently displayed.Why is that?
And interestingly enough, this tendency to show the left side has diminished over time,
especially in the 20th century.
In fact, the left right ratio is now about 1:1.50% left 50% right.
Why is that?
We do know that for many artists, the choice of left side, right side was very important.
There is an image by the Dutch painter Vincent Van Gogh called the Potato Eaters that shows the profiles of a group of farmers.
It's a lithograph, which is a print made from i mages drawn on a stone.
When you print something that way, what you get is a mirror image of the original picture.
The exact same image, except that left and right are reversed,
and Van Gogh was so dissatisfied with the print that he wrote to his brother,
quote ""the figures, I'm sorry to say, are now turned the wrong way."" end quote.
Anyway, why do you think so many painters in the past chose to depict the left side of their subjects' face? Nancy.
Could it have to do with whether the artists were left-handed or right-handed,
like maybe most of them were right-handed, and maybe for some reason they feel more comfortable painting the left side?
Ok, many right-handed artists do find it easier to paint left profiles, and many art historians think that's the reason for the directional bias.
But if that hypothesis, let's call it the right-handed hypothesis, was correct,
you'd expect that left-handed artists would find it easier to paint right profiles.
But the research suggests that left-handed artists find it just as easy to paint left profiles as right.
So any other ideas?
Well, another theory is what's known as the parental imprinting hypothesis,
which proposes that people are more used to seeing left profiles because supposedly right-handed parents are more likely to hold their babies in their left arm.
Well, my sister just had a baby and she keeps talking about how her left arm is getting so much stronger than her right.
Ok, so there's some anecdotal evidence.
So, then when the baby looks up at their parent, what they see is the left profile.
Right. And so the theory goes:the left side of the face becomes imprinted in our memories.
But the parental imprinting hypothesis doesn't explain why left profiles have decreased over time.
I mean, parents are still carrying their babies in their left arm, right?
Exactly! All right, what about the way the artists' studio is organized, specifically the light source.
Remember that the light source determines where the shadows are.
So, if you're a right-handed artists, you'd want to the light coming from your left because you don't want your painting hand to cast a shadow across your canvas, right?
And if the light's coming from your left,
ou'd want your subject to turn to their right into the light. If they do that, what do you see?
The left side of their face.
Exactly, and well into the 20th century,
many an artist's primary light source would be the sun.
And they set up their studio to take maximum advantage of it.
But then what happens as other high-quality, portable, artificial light sources become available?
Well, you could position your subject in a lot more different ways and still have good lighting on your subject and on your canvas.
So...?
You'd expect to see a more balanced ratio of left- and right-side portraits. "
L46C2
"Listen to part of a conversation between a student and her history professor.So I definitely want to write my term paper on American journalism in the eighteenth century.
That old copy of the New York Daily Gazette you showed us,
the one printed from the library's microfilm.
Just seeing a newspaper that was published in 1789...that was really cool!
Yes, reading old newspapers can be a powerful experience,
especially to a budding historian like yourself.
As a resource for scholars and researchers, I don't think any form of publication really captures the day-to-day life of a community better than a local newspaper.
Yeah, I mean, I knew that the number of newspapers exploded in the 18th century,
but I figured they all deteriorated before the technology was invented to preserve them, or you know, make copies.
Well, actually, before the mid-1800s, newspapers were printed on fairly sturdy paper made from cotton fibers.
Those that survived are in surprisingly good shape.
Are there many more copies of the Gazette on microfilm?
Yeah, we've got a great microfilm library on campus.
You'll find it invaluable, I'm sure, as you research your paper.
Um, but also talk to the librarians because they are creating an online archive of their microfilm collection.
l'm not sure of the project's status,
but if it's done, it'll probably save you time.
So, um, 18th century journalism, you must realize that that topic is too broad for this assignment.
I do. So one idea I had was like looking at an important world event like maybe the French revolution of 1789, since we just finished a unit on it.
The readings you've given us were incredibly vivid.I loved them, but they were translations of French writers, historians.
So I thought it'd be interesting to pick the Gazette and one other American newspaper to see how each covered the revolution,
how the journalists reported it from America's perspective.
Hmm, interesting approach.But remember, I'll be grading your paper based on the details you include.
And at some point in your paper,
you'll want to focus on a particular event of the revolution like maybe the storming of the Bastille prison.
How about the formation of the French national constituent assembly?
Sure! That would work.
And since I'm gonna look at newspapers from two cities,
I could read the editorials, the opinion pieces,
to find out what each community thought about the national assembly.
Ok, but, you know, I once attended a history conference where a professor presented a paper on the American press in the French Revolution.
She was discussing the development of democratic ideals here and in France at that time.
But she also pointed out that using old newspapers as primary sources... to be aware that they reflected the values of only a segment of society,
and should not be used to draw conclusions about all Americans.
I don't think I held on to her paper, but it was subsequently published,
so you'll have no trouble tracking it down on the Internet.
Let me give you her name. "
L46L3
"Listen to part of the lecture in an art history Class.Okay. So, When We Were discussing GainSborough's painting, the Blue Boy,
Which he painted in 1770, I mentioned the story that the painting might have been an experiment.
The result of a Challenge.
lt was believed that blue couldn't be an important color in a painting because...Well...it tends to recede into the background.
Not good for your main subject, right?
So to show otherwise, Gainsborough created the Blue Boy,
with the boy featured large in his famous blue clothes...and...well...l guess he proved his point.
But there was another challenge to blue.
It was very very expensive back then.
Now of course, because of modern chemistry, any color is available in tubes at any art supply store.
But in the 18th century and before, it wasn't so easy.
And blue...well...the color ultramarine, the most desired shade of blue,
was made from the precious stone, Lapis Lazuli, which had to be imported all the way from Afghanistan.
And the second most favorite shade of blue,
after ultramarine made from Lapis Lazuli, was a shade a blue that came from another precious stone, Azurite.
But Azurite was...well...harder to work with.
There's evidence that artists would try to get around these difficulties.
For example, use pigment from lapis lazuli or azurite very sparingly,
and also use something cheaper, like smalt, which was made of ground glass.
Thing is, smalt became discolored over time.
So many artists probably avoided blues altogether rather than use something cheap and impermanent.
So, blue, and especially ultramarine pigment,
was a luxury, a status symbol, worth even more than gold at times.
And you even have the wealthy ordering paintings with ultramarine to show others that they could afford something made from this precious pigment,
much in the same way they would order gold leaf.
Actually, the ancient Egyptians did manage to make an artificial blue,
the first synthetic pigment in fact, if you can believe that.
They passed the formula on to the Greeks and Romans, but then it was lost.
Anyway, not only was lapis lazuli hard to get, it was also hard to process.
The recipe was difficult.
The stone had to be ground finely, not easy to do with a rock,
then mixed with melted wax, resins and oils, wrapped in a cloth and knitted like bread dough.
The fine particles of ultramarine were then separated from the rest.
The process was time-consuming, which also contributed to the high cost of producing ultramarine,
and it didn't even yield much usable pigment.
As a result, the French government sponsored a competition in 1824 to find a cheaper way to make ultramarine pigment.
And soon after a process was demonstrated where a combination of coal,
sulfur and other cheap, commonplace substances were heated, creating a suitable synthetic substitute for lapis lazuli.
So there's no doubt that 19th-century artists,
after good synthetic versions were available, used more ultramarine.
Think of the impressionists, for example.
They had a lot more choices or at least, less expensive choices, than painters not that long before them. "
L46L4
"Listen to part of a lecture in a materials science class.So what's the first thing that comes to mind when we talk about uses for copper? Tammy?
The penny. It's made of copper.
Okay, good one. But what's a one cent coin worth these days?
You might get back change.
Like if you go to the store and give the cashier 5 dollars for something that costs 4 dollars 98 cents,
you'll get 2 cents back, but 2 cents does not buy much.
The value of the penny in terms of what it'll buy has gotten so low that there's actually a move afoot to eliminate the coin from US currency.
But there's more to it.
As Tammy implied, the penny looks like it's solid copper.
It is reddish orange with a bright metallic luster when it's new, but that's just the copper plating.
The penny's not solid copper.
In actuality, it is almost 98 percent zinc.
But given the rising value of both these metals, each penny now costs about 1.7 cents to produce.
So it generates what is called negative Seigniorage.
Negative seigniorage is when the cost of minting a coin is more than the coin's face value.
Even though the penny generates quite a bit of negative seigniorage,
there is concern that if it's eliminated,
we'll need more nickels, because more merchants might start setting prices in five-cent increments, 4 dollars 95 cents and so on.
So we need a trusty five-cent piece that can be minted economically.
But the nickel's negative seigniorage is even worse than the pennies.
Each nickel costs the US mint 10 cents to produce.
Also, some of us are pretty attached to pennies for whatever reason, nostalgia, and then those collectors.
And people, if they see a penny on the sidewalk, they'll pick it up and think: it is my lucky day!
Another scenario is that, without pennies, merchants, instead of charging 4.98,
might round up the price to an even five dollars.
So consumer goods would become slightly more expensive.
But on the other hand, some cash transactions would be more convenient for consumers.
And as I said, the government would save money if pennies were eliminated.
But wouldn't the copper industry suffer financially if the US government stopped buying copper to make pennies?
But how much copper do pennies actually contain?
How much...Oh, got it, right.
So what else comes to mind when you think about copper?
What else is copper used for?
I know that copper can be shaped into all sorts of things:
sheets, tubing, and my cousin's house has a copper roof.
Yes, like gold and silver, copper is extremely malleable,
but it's not a precious metal, it's far less expensive than gold or silver.
It's also a superb conductor of electricity so you can stretch it into wires which go into appliances and even car motors.
Copper also has superior alloying properties, it's...you know, when it's combined with other metals.
For instance, how many of you play a brass instrument, like a trumpet or a trombone?
Well, brass is an alloy of copper and zinc.
If your trombone was made of pure copper or pure zinc, it wouldn't sound nearly as beautiful as a brass trombone.
Another alloy, a combination of copper and nickel, resists corrosion.
It does not rust, even with prolonged exposure to water.
But what about the Statue of Liberty in New York Harbor?
It's made of pure copper, but it turned green.
Isn't that a sign of corrosion?
Indirectly. If copper's exposed to damp air, its color changes from reddish orange to reddish brown.
But in time, a green film, called a patina, forms and the patina actually serves to halt any further corrosion.
It is one reason that ship hulls are made of copper-nickel alloys.
These alloys are also hard for the barnacles to stick to.
If these little shellfish adhere to the hull of a ship, it produces drag, slowing the vessel down.
Copper's also a key material used in solar heating units and in water desalination plants,
which will play increasingly important roles in society.
Bottom line: if you are a copper miner, you won't lose any sleep should the penny get...
if you'll excuse the expression, pinched out of existence. "
L47C1
"Listen to a conversation between a student and a music director.Miss Harper?
Yes, can I help you?
Hi, my name's Eric Paterson. I'm a journalism student.
I wanted to ask you about the orchestra.
I' m sorry, Eric. But the orchestra is only open to music majors.
Really? Well, see...
But the policy is changing next year.
After that, if you've taken three music courses, you will be able to audition.
Well, I have taken some music courses and I do play the double bass. So, maybe that's something to think about.
But, actually, I was here about something else.
Oh, sorry. It's I... I get that question all the time. So...
That's okay. The thing is I work for Magna - the school paper and I am reporting on last week's concert.
Now I went to it and I really enjoyed it, but now I'm looking for some background knowledge.
Well, I can refer you to some of the students in the orchestra if you'd like a young musician's point of view.
Uh...l guess that might be helpful. But...um...l am really looking for a little bit of scholarly perspective.
Some history of the music that was performed that evening, where it originated, how it's developed over time.
Well, some of our musicians kind of specialize in Appalachian music.
In fact, that's part of the reason we performed it.
So you really should talk to them, too.
Okay, so we were playing Appalachian music from communities in the Appalachian Mountain regions of the United States.
All right.
Uh...Do you really think you can keep these all in your head?
Oh, don't worry.
All I need are a few key facts. I'm sure I can keep them straight until I get back to my dorm.
So the music is generally based on folk ballads and instrumental dance tunes. It started with Scottish and Irish immigrants who brought over their styles of music.
It's called Anglo-Celtic.
So, people brought their musical traditions with them.
Well, this Anglo-Celtic music was considered an important link to the past for these people, which you can see in the way that Appalachian singers sing ballads.
They have sort of a nasal quality to them, like in Celtic ballads.
In their new land, some of the lyrics were updated,
you know, to refer the new locations and the occupations that settlers had in America.
But at the same time, lots of ballads were still about castles and royalty,lords and ladies, stuff like that, which is what they were about originally.
Okay. And was that some sort of banjo I saw on stage during the performance?
Yes, we are lucky that one of our students, Stewart Telford, has a nineteenth-century banjo, a real antique.
He's able to play in most of the traditional styles.
Did you know that banjos are of African-American origin and that settlers in Appalachia adopted banjos for their folk music?
They became very common in traditional Appalachian music along with guitars and violins, of course.
But if you want to learn about that banjo, talk to Stewart.
That's great, Miss Harper. Thanks a lot.
Now, can you recommend any sources where I could look up more about this?
Sure, I have a great book.
A student has it today, but you can borrow it tomorrow if you'd like. "
L47L1
"Listen to part of the lecture in a literature class.So, urn, in France, you have the French Academy, which was created to uphold standards of literary taste.
It was a very conservative organization.
It tried to keep things a certain way...uh...resist change.
It dictated that French plays should neoclassical in form, you know, have five acts, sophisticated language, etc.
But try as it might, it couldn't stop change.
French drama was changing, though the transition from neoclassical drama to Romantic drama was itself pretty dramatic.
Let's look at a play by Victor Hugo called Hernani, or as the French would say, Hernani.
Although Hugo was a truly brilliant writer of essays, poems, novels, and plays, uh, his play, Hernani, isn't a great play in and of itself.
It's got a really confusing, convoluted storyline.
Critics back then were unimpressed by it,
though it's likely that their own feelings about how plays should be,
neoclassical or romantic, affected their opinions about it.
But its premiere in Paris, in 1830, was anything but ordinary.
Hernani's opening night was probably one of the most important literary events in 19th century France!
What happened was...OK. Hugo was a Romanticist, right?
He was part of a growing movement of young authors and artists who were rebelling against neoclassicism,
against the conventions of neoclassicism.
And what this meant is that Hugo opposed the neoclassical unities that French theater had inherited from Greek drama.
These unities were basically the unity of time, space and action,
meaning that the entire play consisted of just one main event that was unfolding in just one specific place,
usually in the course of one day.
And Hugo found this to be too constraining.
He looked for inspiration in...well...OK.
Hugo is from the 19th century, but he looked to Shakespeare,
several centuries in the past, long before neoclassicism.
For example, in Shakespeare's play, A Midsummer Night's Dream,
the play moves from indoors to outdoors, from the city to the forest, and back again.
So there was a kind of mobility in...in the use of space. And...well...in A Midsummer Night's Dream,
of course the action in that play takes place on a single summer's night,
but in Shakespeare's other plays, in Hamlet, for example, ti me elapses.
People travel; they go to other destinations.
And the action is not limited to one plot.
Hugo also opposed the neoclassical insistence on the separation of genres.
For a neoclassicist, a play could only be dramatic and high art, or comic, well, light-hearted.
And in either case, there was still a sense of decorum.
Characters might make jokes and get into silly situations, but they're still regular people, like not in disguise or anything.
There's still a certain amount of restraint in a neoclassical comedy.
Again, earlier works by Shakespeare provided very different models that Hugo found more appealing.
Many of Shakespeare's plays, even the tragedies, contain scenes with ridiculous, outlandish characters like clowns, so that many of the plays have both qualities: a serious dramatic side and comedic scenes with the clowns that break the drama.
And Hugo, like other Romantics, was also opposed to the artistic rules that the neoclassicists had inherited from the Enlightenment.
The Romantics wanted a more passionate kind of theater and it was more rooted in the individual and the individual sensibility.
Romanticism was political as well, claiming that individuals, people, could govern themselves,
without the need for kings and queens.
There was an ideological struggle between a lot of young people, artists, people who wanted change, and people who didn't.
So of course Romanticism was controversial.
Now, Hernani was a play that incorporated these Romantic conventions.
Hugo suspected that neoclassical audiences would be hostile to this new form and the ideas it represented.
So to protect himself, he rounded up his friends for opening night.
And hundreds of them came to the theater that night.
And Hugo writes about this arrival of the Romantics,
these wild and bizarre characters and their outlandish customs,
which stupefied and infuriated the more conventional theater-goers.
So the play that night took forever to finish because it was interrupted many times and there were these debates in the audience,
between Hugo's friends and supporters, the Romantics, and the Neoclassicists, the supporters of the old school.
Lots of interruptions!
And afterward, what had been a debate inside the theater spilled out onto the street and there were fist fights.
It was a complete free-for-all. And this went on for the next forty-five nights.
Every night that the play was performed,
there was this excitement and controversy that was,
was really an expression of the kinds of passions that...uh...differences of aesthetics and political opinions and taste could give rise to. "
L47L2
"Listen to part of a lecture in a biology class.Now usually when we talk about birds flying long distances, we're discussing seasonal migration.
But there's some species that fly long distances not as part of a migration but as part of their regular foraging for food.
A great example is the albatross.
Albatross are seabirds that nest on islands and forage for food out in the open sea.
And you have one species that forages an average of a thousand miles from its nest.
And I read in another study where one albatross left a chick in its nest and went out in search of food.
And by the time it got back to the nest, it has flown nine thousand miles. Yes, Bob?
But why don't they just build their nest closer to their food supply?
I mean, for one thing, they must burn up a lot of energy flying back and forth and also the parents are gonna have to be away from the nest that much.
Aren't the chicks gonna be pretty hungry most of the time?
Ok, good question.
The chicks are capable of going for long periods of time without food,
which works out nicely since as you point out, they may not get to eat that often.
As far as the parents go, well, first, they typically can't get enough food in a single location.
So they have to visit several places on the same foraging trip.
And the locations of good foraging grounds tend to be very far apart.
And second, they can't always nest on an island that's closest to the best feeding ground because some of those islands have too many predators on them.
Predators that would just love some little chicks to snack on.
So I don't think they have much choice.
But it still works out because albatross fly using a technique called dynamic soaring,
which enables them to cover very long distances while expending very little energy.
If it weren't for that, you'd be right. They would probably burn up all their energy just flying back and forth.
Another factor is albatross lay only one egg at a time.
So when the parent returns with the food that one chick doesn't have to share it with a lot of other chicks.
Yes, Nancy?
So you're saying that they might easily fly a thousand miles over the open ocean when they're looking for food?
That's right.
Then how do they know how to get to the food?
I mean, which direction to take to get to the food and how do they find their way back home?
Good point.
And the truth is we are not sure.
It's very difficult to keep seabirds in captivity where you can study them.
And it's very difficult to study them in the wild, you know.
But we think that a lot of what we've learnt about songbirds probably applies to seabirds as well.
So we're thinking that albatross could make use of two different kinds of compasses if you will, a magnetic compass and a celestial compass.
The magnetic compass somehow makes use of Earth's magnetic field,
much the way a standard compass does.
But to prove this, we would have to find some kind of magnetic sensory organ in birds.
And we are not sure that we have.
We have found in birds a mineral called magnetite,
which we think might be somehow related to this, because magnetite is a natural magnet.
But the problem is that we've also found magnetite in non-migratory birds,
which suggests that it may in fact serve a completely different function, not related to navigation at all.
Um, and the other compass, the celestial compass makes use of the stars, more or less the same way humans have historically used the stars to navigate in the open sea.
So that's the way we think albatross navigate.
So anyway, you know, think about it,
how about if you had to go a thousand miles every time you wanted to get a bite to eat?
Yeah, and we complain about having to walk all the way across campus to get to the cafeteria.
Yeah. "
L47C2
"Listen to a conversation between a student and his professor.This is not what I had in mind when I assigned a film review.
It isn't?
No. What you wrote is a synopsis, a detailed summary of the movie, but it's not a review.
It's not? I guess I'm a little confused cuz...isn't that what a film review does?
You know, describe the film?
Sure. In part. But a good review has to do more.
But this is probably not your fault.
I'm starting to think that I should have explained the assignment better because...well...I got a lot of summaries and very few reviews.
So it wasn't only me.
Hardly. I just assumed that everyone would know what to do.
So...um...what else is a review supposed to do?
Well, it should also analyze the film, discuss its strengths and weaknesses,
maybe compare it to other movies,
even mention why the reviewer did or didn't like it.
You mean it should have been more personal?
For starters, or maybe subjective is a better word than personal.
Yes. It should have been more subjective.
Maybe I could rewrite it?
Well, I don't know about rewriting it.
Too many people seemed to have missed the point.
I think I may have to forgo evaluating this one.
Instead maybe we'll just devote a class to discussing what it takes to write a good film review.
Or maybe...hmm...you know, I have a colleague who writes film reviews for the local paper.
Maybe I could ask her to come to class and describe what she does and then have everyone rewrite their reviews.
So, she would talk about what a film review should be like, so we'd know what to do.
Well, more than that.
A professional film reviewer gets to see movies sometimes before they are even released.
They get advance copies —— usually a video or DVD —— to watch at home or they go to a movie as soon as it opens in the theaters.
Um...seeing it on the big screen in a theater, doesn't that affect the experience?
Of course! Having other people there can...can affect the review, too.
So, for the next assignment, I might ask everyone to review one of the films the film club shows every weekend at the theater on campus.
There is no admission charge.
They are free to students and the movies are shown on Friday and Saturday nights, plus Sunday afternoon.
So, everyone should be able to see one.
Yeah, that should work.
But for this time, will we have to rewrite our reviews?
Well, let's take it one thing at a time.
Let me talk to my colleague. "
L47L3
"Listen to part of a lecture in a sports management class.So, I want to end today with a topic that many of you have questions about when you come to see me during my office hours.
A lot of you have told me you are specifically interested in careers as coaches.
Now, it doesn't matter what sport you are interested in coaching, volleyball, basketball, swimming...
There are some considerations for all new coaches to think about as they plan their careers.
A recent study, a survey of high school head coaches,
helped identify some obstacles,
some things that head coaches felt they were not prepared for as they began their careers.
They were surveyed to determine what things they would do differently if they were starting their careers over again.
Based on their responses, several themes emerged.
The largest number of responses was in the area of relationships.
79% of the coaches indicated that if they had to do it all over again,
they would do things differently in this area.
They said they'd deal differently with assistant coaches, parents, student athletes, school administration, and, and pay more attention to those relationships.
The second most critical area for these coaches was organization and administration.
To them, this meant things like better managing their budgets,
and delegating responsibilities, making sure that even minor things were taken care of,
like pre-game meals, those sort of things.
Excuse me, professor,
I know good nutrition is important, but organizing pre-game meals isn't really something you consider when you are thinking about going into coaching as a career.
No, I guess not, Kenny,
but it's more an example of paying attention to the details, being organized.
I do want to emphasize that the profession of coaching is about more than just wins and losses.
In fact, winning is probably stressed too much.
At its best, I'd say coaching, especially in high school and college,
is about teaching life skills through game strategy.
Of course, coaching requires a specialized body of knowledge.
If you coach tennis, you need to know the rules of tennis.
If you are a football coach, you need to know all about football strategies.
And those are the sorts of things that you'll get in your classes here at the university.
But if coaches spend too much of their time on game strategy,
well, you see, maybe that's secondary too, to the knowledge and skills,
you'll need for the other roles you'll undertake as a coach,
especially, as that survey emphasized,
skills in dealing with people, and, and administration.
But, how do you...
how do you improve in those areas, I mean, I'm gonna be an assistant coach at a high school beginning next month, and ...
Really? Nice going, Kenny!
Yes, that's wonderful!
Thanks. I'm excited.
So, congratulations!
Ok, well, to get better organized, one thing is take courses in business management and not just the sports management courses in the physical education department,
other business and finance courses.
Oh, oh, but wait a minute.
You said you are starting next month?
What sport will you be coaching?
Uh, gymnastics, mainly.
Okay, in my career, I've learned, well, as part of building and maintaining strong relationships and working on administrative skills,
you've got to consider the other needs of your team beyond the sport itself.
Remember, the team members are athletes and students,
and remember, if you are enthusiastic about what you are doing,
well, enthusiasm is...is catching, right?
You want team members to enjoy participating.
Right, but what about setting rules for your team, and, is it better to be strict or not so strict?
Actually, I don't believe in having a lot of rules.
And coaches often do have too many.
I think that can get in the way of leadership and box you in.
I think people sometimes set rules just to make things easier for themselves.
That way maybe later they just can refer to the rule and avoid making a choice.
You know that kind of person I'm talking about, right?
But that's not to say the team shouldn't have any rules at all.
Of course they need some.
So early in a season, or when you first take a new job,
establish a few basic ground rules for what is acceptable and non-acceptable behavior.
So, what are some good ones?
Well, a...a couple rules a coach should have are:
insist that players be on time, and insist that they practice hard, and give their best effort.
And when you do establish a rule, stick to it. "
L47L4
"Listen to part of the lecture in a meteorology class.Now, Earth's atmosphere is sort of like a giant weather machine, right?
Uh...with air and water being its key components.
A machine powered by energy from the Sun.
So we need to consider the role that air, or more specifically, wind, plays in this machine.
So wind is really nothing more than moving air, right?
Now, as air is heated and becomes warmer, it expands, it becomes less dense.
When air in a particular area is heated,
you get a concentration of warm air in an area of low pressure.
Likewise, when you get a concentration of cold air,
that air's gonna be very dense, so it's gonna create an area of high pressure.
If you have an area of high pressure next to an area of low pressure,
the colder, high pressure air will start moving toward the area of low pressure.
Right? And the warmer air will move away, rising above the cooler air. Okay?
Uh...yes. Linda?
So wind is actually generated by the Sun?
Well, Earth's rotation plays a role.
And there are other factors and we'll come back to all that.
But, principally, yes. The Sun creates the temperature differential that creates the areas of high pressure and low pressure that create wind.
Um...l don't get what...how it causes a temperature differential.
Right. Good. This will take us to the role of wind in the climate.
The key is that the Sun warms up different parts of Earth at different rates and to different degrees.
For example, at sunrise, the land heats up faster than the ocean.
That's why you get morning sea breezes.
The air over the water heats more slowly than air overland,
so during the early morning, it's cooler and denser than air overland,
so it moves in toward land.
A sea breeze.
What else?
The Sun's energy is more intense near the equator than it is near the poles,
so you've got masses of warmer air over the equatorial regions,
and masses of cooler air over Polar Regions.
And these masses are constantly interacting with each other, which is critically important for Earth's climate.
One result of these interactions is that equatorial air masses move away from the equator and in the process those equatorial winds actually take heat away from the equator and transfer it to some cooler part of Earth.
And by redistributing this energy, the Sun's energy really,
winds play a critical role in maintaining a temperature balance from the poles to the equator.
Now, winds also help Earth maintain its balance in another way:
by transporting water from one part of Earth to another.
Water's contained in the air in the form of vapor,
mostly through evaporation, mostly from the oceans.
So when the air moves, it carries the vapor with it to some other parts of Earth,
where it can deposit it as rain or snow, or some other form of precipitation.
Now, actually, the transfer of heat and water by way of the wind are very closely related,
because a primary way that heat energy is transferred by wind is mediated by the process of evaporation.
What happens is that a certain amount of heat energy is required to convert liquid water into vapor.
So when water evaporates from the ocean, it takes energy to convert that water into a gaseous form, into water vapor.
But that heat energy, that conversion energy, doesn't raise the temperature of the water vapor or the air, it's just stored in the water vapor.
Then later when the water vapor converts back to liquid water, that energy is released.
So when water evaporates, energy is taken from the ocean, and it's stored in the water vapor, in the air.
Then the air, the wind, transports the water vapor to some other part of Earth.
Then the water vapor converts back into liquid water.
It rains, in other words.
And the heat energy that was stored in the water vapor is released into the new environment.
Okay? So the transfer of heat and the transfer of water are very closely related.
And what's the primary vehicle for this transfer?
The wind! So wind is a very critical element in the redistribution of both the Sun's energy and Earth's water. "
L48C1
"Listen to a conversation between a student and a university employee at the campus employment office.Hi, can I help you?
I hope so. My name's Mark Wickman. I'm...
Don't I remember you from last year?
You worked in, uh, where was it? The art library?
Yeah, you're good. That was me, and I really enjoyed the work.
Right, yeah. Your supervisor gave us some really great feedback at the end of the year.
Oh, ""he's so organized, always on time, helpful...""
Really, well.. I'm glad. It was a good job.
Well, we usually try to match student's jobs with their academic interests.
Yeah, um, I'm not exactly sure what career I'm headed for. But librarian is a possibility.
It was a great experience to learn how it works and meet some people working in the field. But for this year, well, that's what I wanted to ask about.
Oh, how come you waited so long to come in?
You know how fast campus jobs fill up. If you'd come in earlier, you could probably have gotten the library job again.
I mean, since you have the experience from last year, you don't need the training and all.
But it's been filled now.
Yeah, I know.
But I plan to get a job working at a restaurant off campus this year.
I really need to make more money than I did last year, and working as a waiter, there's always the tips.
But I've tried a ton of places and I haven't found anything.
I know it's really late, but, well, um, I was wondering if maybe there was some job that hadn't been taken or maybe someone started a job,and you know, had to drop it or something.
Well, I doubt you'll find anything.
Well, could you, could you possibly check?
I know it's a long shot, but my friend Susanne, she takes photography classes in Harrison Hall and...um...she sort of thought there might be an opening in the janitorial staff.
Urn, why does your friend, the photography student, think she has information about a janitorial staff opening?
I'm pretty sure those jobs are filled. In fact, I remember taking lots of applications for them, but let me double check it online.
She said the whole studio arts building and especially the photo lab have been kind of, uh, sort of messy lately,
I mean, she says there's...uh...chemicals and stuff left out, and you know, it's like no one's been cleaning up.
Oh, but that could just be, you know, students using the lab after hours or something, like after it's been cleaned.
Hmm, hang on.
There's a...There's...um...an asterisk gap next to one of the job numbers here.
There's a note.
Let's see... Ha, your friend's right.
Seems like one of the student janitors quit a couple of weeks ago for some reason.
Well, whatever, it looks like this is your lucky day.
Wow! That is so great.
So who's the contact person?
Check with the janitorial office.
Fine. Thanks so much. "
L48L1
"Listen to part of a talk in an art history class.So today we are going to continue our discussion of 20th century photography in the United States.
Last time we were talking about Alfred Stieglitz and we saw that one of his goals was to introduce Americans to European Art.
Today, we are going to look at another photographer from the early 20th century.
Yes, Jennifer?
Before we get to that, I had a question about Stieglitz.
Sure.
Well, Stieglitz was married to Georgia O'Keeffe. Right?
That's right. Stieglitz was married to her, promoted her work and actually, took some amazing portraits of her when they were married.
For anyone who's not familiar with this, we are talking about the American painter: Georgia O'Keeffe.
Ok. Well, I was wondering...Georgia O'Keeffe.
You know I've heard her name so many times and I've seen some of her work. But she's not mentioned in any of our reading about photographers from that time.
Oh. Well, O'Keeffe was really more of a painter.
I thought she was a photographer, too.
I mean, I just saw one of her photographs in a museum the other day.
I think it was called ""Red Leaves on White"" or something like that.
Oh, right! Yes. ""Large Dark Red Leaves on White"" is the complete title.
It's a fairly well-known painting by O'Keeffe.
Oh, oh, okay. What was I thinking?
I guess I should have had a closer look.
No, no. That's a really good observation.
I mean chronologically that would be impossible.
When she did that painting, color film hadn't even been invented yet.
Neither had the right technology to blow pictures up that big to show that much detail.
But that painting and some of her other paintings do reveal the... the influence of photography, like, uh, she would crop her images.
She would make a frame around part of an image, say, just the very center and then cut off certain parts, the parts outside that frame, to create the effect she wanted, the way a photographer does.
And those paintings are close-ups, like you might see today, of a person or a flower in a photograph.
Now, those techniques were certainly around and being used by photographers then.
But just in photographs, which were smaller not as big as what O'Keeffe was painting.
Also, O'Keeffe studied under an artist named Arthur Wesley Dow.
That's DOW, D-O-W, who advocated focusing on simple basic forms, like the lines of a flower and its petals and he wanted forms to be isolated from their original settings.
He believed that, by doing that, an artist could reveal an object's, its essence.
He'd do things like...like...have students take a simple ordinary form, like a leaf, and explore various ways of fitting all of it into a square, maybe bending it around to make the whole thing fit into the frame. Pierre?
It sounds like maybe O'Keeffe borrowed most of her ideas. The stuff we might think of as being hers, she got them from other people.
She didn't really have a style of her own.
Well, virtually, all artists are influenced by other artists, by their predecessors, by their contemporaries, their teachers...
Artists build on what other artists have done.
But if they are talented, they take it in some unique direction to develop their own distinctive style.
O'Keeffe liked to create abstract interpretations of real objects.
In the painting Jennifer mentioned,
Large Dark Red Leaves on White, in addition to exaggerating the size of the leaf, O'Keeffe juxtaposes it against a silver or whitish background.
So that's more of an abstract setting for it, and so on.
Now, O'Keeffe wasn't the first artist to create an abstract interpretation of a real object but she used that approach to express her experience of the object she was painting.
So she presented a vision that people hadn't seen before.
It's unique.
It's compelling.
She didn't expect other people to experience the object the way she did.
She knew they'd look at her painting and hang their own associations on it, which is true for artwork in general, I think.
That's just the way the human brain works. But at least they'd be taking a careful look at something they'd never really paid much attention to. "
L48L2
"Listen to part of the lecture in an Earth Science class.The class has been discussing volcanoes.
Okay. We know the Earth's surface, the crust, is made up of tectonic plates, and these huge slabs of rocky crust are slowly sliding over or under or past each other,
and we said that most of the world's volcanoes occur at the boundaries of these tectonic plates where you have hot molten rock squeezing up through gaps between the plates.
But some volcanoes occur not at the edges, but in the middle of a continental or oceanic plate.
The Hawaiian Islands, for example,
are thousands of kilometers away from any plate boundary, and yet you have vast amounts of magma,
molten rock or lava, flowing up through the earth's crust, which means, of course,
that volcanic activity there can't be explained simply by plate tectonics.
So, how do we explain these volcanic anomalies, these exceptions to the general rule?
Well, back in 1963, a geophysicist by the name of Wilson came up with a hot-spot theory to explain how this particular type of volcanic activity can occur,
and can go on for maybe tens or even hundreds of millions of years.
Wilson's theory was that: hot spots exist below tectonic plates,
and they're the cause of these volcanoes.
But what causes the hot spots?
Hmm, well, the most popular theory that's been proposed is the plume hypothesis.
According to this hypothesis, plumes, uh, basically columns of extremely hot magma.
These plumes well up from deep inside the planet's interior,
maybe even as deep as its core,
and rise all the way up to melt through the Earth's crust.
Imagine a burning candle, and imagine moving a sheet of heavy paper slowly over the flame of the candle.
You're gonna get a series of burned spots in the paper,
well, that's just like what's happening with the Hawaiian Islands, but instead of a sheet of paper,
you've got a tectonic plate,
and it's moving over this plume of intensely hot magma,
and rather than a series of burned spots in the paper.
You're getting a chain of volcanic islands where the hot plume melts through the crust under the Pacific Ocean at one point after another with active volcanoes on the younger islands that are now just above the plume,
and the other islands, well, the farther away from the plume they are now, the older they are, and the longer ago their volcanoes went dormant or extinct.
Incidentally, volcanic islands may seem small,
but the island known as the Big Island Hawaii is one of the tallest topographic features on the planet, more than five kilometers from the sea floor to the ocean surface,
and almost that much again, up to its highest peak.
That's nearly ten kilometers from ocean floor to the highest point on the island,
which makes it taller even than Mount Everest.
So, you can imagine the huge amounts of magma, or lava, that've flowed up to form even just this one island,
much less the whole chain of islands.
Now, the Plume Hypothesis provides a pretty elegant explanation for a volcanic anomaly, like the Hawaiian Islands.
But, while it's hypothetically attractive,
there's very little direct evidence to support the theory, because so far,
no one's been able to actually observe what's happening that far beneath the Earth's crust.
Some studies have been done, seismographic, geochemical,
where the data's consistent with the model, but they aren't definitive proof.
Even the model supporters are uncomfortable claiming that it explains every volcanic anomaly.
And like any popular theory, I suppose, it has some determined critics.
These critics have put forth a number of alternative theories, all unproven so far.
But one well-regarded theory is the crack hypothesis,
which assumes that hot spots are created when a piece of the crust gets stretched thinner and thinner and the resulting stress causes small cracks to open up at weak spots in the crust,
and it's through these cracks that magma pushes up to form volcanoes.
Proponents of the crack hypothesis consider this a widespread phenomenon and believe that magma's not coming up from deep within the Earth's interior,
but rather from just beneath the surface crust.
This hypothesis is attractive, because it fits with what we already know about plate tectonics and it fits what we know about some secondary smaller hot spots, but how well does it explain the Hawaiian Islands?
Could a series of random cracks produce that same particular string of Islands that's sequenced so neatly from old to young?
You know, it worries me when a theory depends on coincidence to produce results. "
L48C2
"Listen to a conversation between a student and a professor.Hi professor, I was hoping to ask you a few questions about the class you're teaching next semester,
the course on Polish drama I was thinking of taking it.
Well, that's an upper division course. You don't look familiar to me.
Are you a student in this department? No, actually I'm not.
Ok, have you had other classes in the Slavic languages department, here or somewhere else?
No, that's the thing. I was just wondering how good my Polish would have to be whether the class is taught Polish or not.
Well, you'd have to have some knowledge of it.
By that level a lot of students are quite fluent, plus there're some native speakers in the department.
And we don't plan for it to happen,
but it's pretty common for the discussions to kind of move in and out of English and Polish and it can be difficult to follow.
So, how well do you speak Polish?
Hmm, not so great.
It's just that my father's from there.
So I'm interested in learning about...
You know, Polish history, Polish culture, plus I'm studying drama.
I'll probably major in it.
I love plays. So I thought your course might be perfect.
Hmm, to be honest with you, you have to realize that we'll be watching videos of performances.
And maybe if we can swing it, even watch a live performance and those won't necessarily be in translation.
Also, texts, texts are sometimes available in translation. But even then some references will be to the original.
I'd hope you'd be fairly confident in reading. To be honest, it sounds totally over my head.
You know what? I believe they'll be offering a survey course on Polish literature.
Let me check here.
Yes, I thought it was being offered this time, Professor Jowaski's teaching it.
Let's see. It covers the major works,
you know, epic romantic poetries, the novels, and it does cover one or two plays.
And this is in English?
Yes, you'll be reading mostly English translations and the discussions will be in English.
Hmm, novels and poetry.
They'll provide you with a great historical context for the plays.
So when you do get to them, you're gonna really have a feel for the times they lived in, so to speak.
Plus this course might also give you the impetus to learn more Polish, you know, get it to the level where you'd be ready for the other class.
Hmm. "
L48L3
"Listen to part of the lecture in a biology class.Ok, today I'd like to spend some time going into more detail about symbiosis.
Symbiosis, what is it? Anyone?
Urn, I thought it's when two organisms are in a relationship that they both benefit from.
Well, at least that's what I thought it was until I did the reading last night.
Now, I am kind of confused about it, because the book used that definition to describe mutualism.
Could you explain the difference?
Good. I was hoping that someone would bring that up.
Sometimes scientists working in different fields use the term symbiosis to mean slightly different things.
And it can get confusing.
Uh, for example, when symbiosis is used as a synonym for mutualism.
But there are quite a few of us out there who think there should be a clearer distinction made between the two.
Ok, where to begin...
Um, the original definition of symbiosis is pretty simple.
It simply means living together.
So, any close relationship between two organisms of different species would be considered a symbiotic relationship,
including positive and negative relationships.
Mutualism then is a kind of symbiosis,
a specific type of symbiotic relationship where both organisms benefit somehow.
So, your book is correct.
Now, I want to make it clear that, um, the positive result from being in a mutualistic relationship doesn't have to be equal for both organisms.
It's not a one-to-one ratio here.
Is everyone with me so far?
Symbiosis, general term;
mutualism, a narrower or more specific kind of symbiosis. Okay.
Now, let's take a closer look at mutualistic relationships.
Um, I'll start off by describing a case of mutualism that involves a certain butterfly species found in South Africa and Australia.
It's a good example of how dependence on a mutualistic relationship can vary.
Ok, there's this butterfly family and I'll spare you the fancy Latin name because it is not important for our purposes here.
Uh, I'll call them Coppers and Blues, well, because most members of this family have blue or copper colored wings.
I think this is one of the most interesting cases of mutualism.
These butterflies require the presence of ants to complete their life cycle.
Their interaction with ants is obligatory.
So, this is what happens.
A female butterfly of these Coppers and Blues will lay eggs only on vegetation where there are ants of a particular species.
The butterflies can smell,
well, ants leave behind pheromones, a special chemical signal.
The butterfly recognizes the ants' pheromones on the plant and then the newly hatched butterflies, the caterpillars will feed on this plant after they hatch from the eggs.
As the caterpillar gets a little older and find shelter under nearby rocks or stones to protect itself from predators.
It's always attended or escorted by ants.
And it always makes its way back to the host plant to feed,
guided by the ants,
the ant escort service, so to speak.
Now, why would the ants go through all this trouble?
What's their benefit? Mary?
It's probably related to food?
Uh-huh? You are onto something.
Ok, ants feed on sweet stuff, right?
So the caterpillar must have some kind of special access to honey or sugars, or something like that.
Maybe caterpillars produce honey somehow.
On second thought, um, I'm probably way off.
You are pretty close actually.
The caterpillars have a honey gland, an organ that secretes an amino acid and carbohydrate liquid.
The caterpillar secretes the liquid from the honey gland, rather large quantities, enough to feed several ants.
But what makes this relationship obligatory for the caterpillar?
Well, if the ants don't feed regularly on the liquid from the caterpillar's honey gland, the gland overloads and gets infected.
The infection will kill the caterpillar and it will never reach its final stage of development, becoming a butterfly.
John?
Ok, I just want to make sure I'm following here.
The caterpillar needs the ants or it won't make it to the stage where it can become a butterfly.
And the ants do this because they get an easy meal out of it, right?
But the ants don't absolutely need the caterpillar for survival, 'cause they can get food from other places right?
So it's still called mutualism even though it seems like the caterpillar's getting way more out of it.
Oh, wait, you said they don't have to equally benefit. Never mind, sorry.
Yes. But there is a type of mutualism where the relationship is necessary for both organisms to survive.
It's called obligatory mutualism.
And we'll talk about that in the next class. "
L48L4
"Listen to part of a lecture in an American History class.We have been talking about the transformation the industrialization of United States economy in 19th century.
As the country shifted from an agricultural to an industrial base, political power shifted too.
Businesses became... a lot of power went...went...went...went from the government into the hands of business leaders.
So, why did this happen?
How did an elite group, a few business giants,
how did they end up dominating, controlling a number of important national industries in the last quarter of the 19th century?
How did they get to be so dominant?
How did they figure out?
How did they take advantage of the new industrialization of American society?
Well, consider the example of Andrew Carnegie and the steel industry.
We have already discussed the development of a national network...a national system of railroads.
Well, this growth created a tremendous demand for steel.
A national railroad system needs a lot of railroad tracks, right?
And Carnegie seized the opportunity.
He built the world's most modern steel mill.
And he came up with a system of business organization called Vertical Integration.
Vertical Integration just means that...all...every single activity of a particular industry's processing is performed by a single company.
In the case of the steel industry, this means the mining of iron ore, the transportation used to get ore from the mine to the mill, turning the ore into the steel,
the manufacturing process and sales. Carnegie controlled all of these.
He practiced Vertical Integration on such a large scale that he practically owned the whole steel industry.
This, of course, gave him a lot of political clout.
Just a quick sketch, but you get the idea, right?
Here is another example: John D. Rockefeller. Rockefeller owned an oil refinery, but he wanted to expand his business.
Since there was lots of competition in the industry,
he thought the smart way to go about it would be to buy his competitors' businesses.
But at the time it was illegal for one corporation to control another.
So what he did was: he created an organizational structure called a trust.
A trust is... well I don't have to go into that now.
What matters is that a trust created a single, central management team.
And that team directed the activities of what otherwise still appeared to be independent companies.
This new...uh...legal entity worked so well that at one point Rockefeller controlled 90% of the country's oil refineries,
which again gave him lots of political power.
So you've got two different approaches to expanding a business, and both were quite effective.
Of course, these weren't the only two examples.
A number of big businesses run by powerful individuals developed across a wide range of industries, like railroads, food processing, electricity.
But what they all had in common was: the government let them operate pretty much how they wanted to.
So why did they do that?
Why did the government keep such a low profile and allow individuals to gain so much control of the industries?
Well, obviously, they had the wealth and the power to influence political leaders.
But also, the truth is that these industry leaders made a significant contribution.
Their investments in technologies led to the development of many new production techniques, which strengthened the economy.
And many of them gave lots of money to charity.
Andrew Carnegie was particularly admired for his generosity.
But there was one thing in particular that gave them power.
And that's they were beneficiaries,
probably the biggest beneficiaries of a theory,
a dominant political theory in the 19th century, something called laissez-faire doctrine.
Laissez-faire roughly means ""let it alone"".
And that pretty much summarized the theory's philosophy.
The idea was that government should leave business alone, allow it to operate unregulated.
Legislators weren't supposed to pass a lot of laws, or worry about regulating business practices.
When people did challenge a company's business conduct,
I mean, I mean, in court cases, well, the few laws that did exist were usually interpreted in favor of business interests.
But over time, it started becoming increasingly obvious and troubling to the public that some of these big companies simply had too much control.
There were criticisms that owners had too much opportunity to exploit workers,
workers and consumers, because they could control prices and wages.
And small business owners and small farmers couldn't compete.
So there was bad press, bad publicity, enough that the government eventually felt it had to do something.
So it passed two key pieces of legislation.
One law was designed to regulate the prices set by the railroads;
another made it illegal for trusts to be used to limit competition.
Both were aimed squarely at reducing the exclusive control that existed in some industries. "
L49C1
"Listen to a conversation between a student and a librarian.Hi.I need to get into special collections,in particular the british literature.
I was working with some of the William Blake books.
Well,then you must know that access is restricted.
Um,I was in a seminar with Professor Gray and she authorized access for us.
Oh,if that's the case,let me check.
Right.Yeah.But it looks like that expired at the end of last semester.
But I really need to get back in there.See...I didn't quite finish my project.
Aha!The plot thickens.
Well,it's easy enough.
Have Professor Gray authorize you again.
You see,these editions are rare and shouldn't be handled more than necessary.
Can you work from later editions or microfilm?
Not really.Actually my project...
Well,it involves some annotations in the particular edition here.
They haven't been reproduced because they are really not part of the text.
You know,they generally clean them up.
They are quite hard to see.
Well,often the characteristics of the manuscripts have been recorded.
These types of extraneous markings might also be noted.
I don't think they are.
They are very faint,and,well,I think I have a new angle on them.
There was a study once a long time ago about these notes that everybody else has taken for granted without checking for themselves.
I think there might have been a mistake in the past,that they were misread.
So get Professor Gray...
Uh...she's away this semester I had to beg her to giveme extra time on this project.
I haven't even received a grade in the class yet.
And this class is a prerequisite for other classes in my major.
I really need to see those books so I can finish this project and get back on course to graduate on time.
Everybody has special circumstances.
Two hours?One hour?I promise to be careful.
I just need to look at a few pages with a strong magnifying glass.
Well,I can let you in without authorization from your professor.
Can you get in touch with her somehow?
Maybe she'd be checking her email.
I really thought I would be able to straighten this out without her.
You know,she did me a huge favor by giving me extra time.
I feel like I'm skating on thin ice with her.
You know,you were lucky to have had permission to look at the books last semester.
If we don't maintain our policies,they'll disintegrate.
I know.Would an email from her or a phone call be good enough? "
L49L1
"Listen to part of a lecture in a geology class.Alaska is fascinating to geologists because of its incredible landscapes.
Permafrost has a lot to do with this.
That is the areas where the ground,the soil,is always frozen,except for the very top layer,
what we call the active layer of permafrost,which melts in the summer and refreezes again in the winter.
The northern part of Alaska is covered in lakes,thousands of them.
And most of these are what we call thaw lakes,T-H-A-W,thaw lakes.
I'm going to show you a few sketches of them in a minute,
so you'll have a good idea of what I'm talking about.
So how these thaw lakes are formed has to do with...
OK.It start with ice wedges.
The top part of the ice wedge melts.
Should I back up?
Ice wedges form when water runs into cracks in the ground,the permafrost,then freezes.
You ever see mud after it dries?
Dried mud has cracks because when it dries it contracts,it shrinks.
Well,in winter permafrost behaves similarly.
It shrinks in winter because it freezes even more thoroughly then.
And as it shrinks,it froms deep,deep cracks.
Then in the summer,when the active layer,the top layer of the permafrost,melts,
the melt water runs into those cracks in the permafrost,
then freezes again,because that ground,the ground beneath the active layer is still below freezing.
So you have wedges of ice in the permafrost.
Now,the ice wedges widen the original cracks in the permafrost because water expands when it freezes.
All right,OK.
Then in the autumn,the active layer on top freezes again.
Then in winter the permafrost starts contracting again and the cracks open up even wider.
So the next summer when the active layer melts again and flows into the widened cracks and freezes,
it makes the cracks even wider.
So it's sort of a cycle through which the cracks and the wedges grow wider and wider.
So when the ice wedge reaches a certain size,
its top part in the active layer turns into a little pond when it melts in the summer.
And that's the beginning of your thaw lake.
There are thousands of them in Northern Alaska.
One of the most fascinating things about these lakes and this is important,
is that they mostly have the same shape like an elongated oval or egg shape,
and what's more,
all the ovals are oriented in the same way.
Here is an idea of what they look like,
what the landscape looks like from an aerial view with the lakes side by side.
There's been considerable research done to try to figure out what causes them to be shaped and oriented this way.
We know that the shape and orientation are caused by the way the lakes grow once they are formed.
But the question is what makes them grow this way?
One theory sees winds as the cause.
This region of Alaska has strong winds that blow perpendicular to the lakes.
What happens is wind blows straight into the longer side of the lakes.
Now,wouldn't that erode the lake bank in that direction?
Same direction as the wind?
Well,no.
Actually,what happens is that the waves caused by the winds build a sort of protective layer of sediment.
It's called a protective shelf along the bank of the lake directly in front of them.
So that bank is shielded from erosion and the waves are diverted to the sides,to the left and to the right.
And that's why the left and the right banks start eroding.
Get it?The bank straight ahead is protected.
But the lake currents,the waves erode the banks to the sides.
That's the current model,the wind erosion model,which is generally accepted.
But there is a new theory that says that thaw slumping,not wind,is what shapes the thaw lakes.
Thaw slumping...
Ok.Sometimes in the summer the temperature rises pretty quickly.
So the active layer of permafrost thaws faster than the water can drain from the soil.
So the sides of the thaw lakes get like mushy and slump or slide into the lake.
Then the lake water spreads out more and the lake gets bigger.OK?
Also in that part of Alaska the terrain is gently sloped,so the lakes are all on an incline.
Here,now,this is an exaggeration of the angle.The hill is not this steep.
But see how with the lake's banks,the side that is farther downhill,it's smaller,lower.
This short bank thaws faster than the tall one does,so it falls into the lake,it slumps much more and much faster than the other bank.
When short banks of many lakes slump,
they move farther downhill and the lakes grow all in the same downhill direction. "
L49L2
"Listen to part of a lecture in an education class.The professor is discussing the Italian educator Maria Montessori.Ok,if you did your reading for today, then you were introduced to a very infiluential alternative to traditional education.
This educational philosophy and methodology was pioneered in Italy in the early 1900s by Doctor Maria Montessori.
It's called the Montessori method.
But what made the Montessori method for young children so different?
What made it so different,so special?
It's based on very different ideas about how kids learn best,right?
Um-hmm...It was groundbreaking.
To begin with,unlike the traditional classrooms at the time,the Montessori classroom environment was more suited to the child.
The furniture was child-sized.
Well,it's that way in almost all schools now,but that wasn't always the case.
We can thank Montessori for this.
You won't see any long benches with children in rows or heavy desks that separate children.
Children are free to interact with each other.
And in Montessori classrooms,the furniture is lightweight,so children can move it around easily,
and having furniture and materials made to fit them makes kids feel more competent.
This fits in with Montessori's notion of liberty and autonomy.
Children are free to move around the room and they learn to do things for themselves.
I'm not sure I get that part.
It sounds like potential chaos.
Oh, no, no, no.
Let's not confuse this liberty of activity with lack of discipline.
In fact,teachers have to maintain this specific environment carefully through a number of rules,
which are generally about respect and what's right.
It's just that the child needs freedom of choice to develop independence and self-direction.
Also,unlike what happens in most conventional classrooms,children choose their own activities.
They may be guided by the teacher,but it's ultimately up to each child to select tasks,
which brings us to the manipulative equipment you find in a Montessori classroom,
like little boards that have rough or smooth surfaces,or blocks that can be stacked into a tower.
Now this equipment was designed by Montessori over time with much experimentation,
designed...well,designed to help children teach themselves through playing.
Well,what do the teachers do?
I mean if the kids are teaching themsefves.
Ah,well,that's a good question.
To start,a child may not work with an activity until the teacher has demonstrated its proper use.
Then the Montessori teacher's job is to observe the child's play,because when the children play,they are acquiring the bases for later concepts.
So the teacher helps motivate and focus each child and monitors the child's progress,but does not interfere with the child's observations and deductions.
That was and still is a novel idea,and for many teachers not the easiest thing to do.
In facts,for some is very difficult.
Montessori herself called the teacher a director.
Remember,the independence of the learner lies at the heart of the Montessori methodology.
Ok,yeah,it does seem like that the teacher need a lot of training and patience.
True.As I said,it is not easy for a lot of teachers to step back like that,but getting back to the equipment.
Basic Montessori equipment can be divided into a number of major subject areas such as practical life,mathematics and what is called sensorial.
With a sensorial equipment,the children can explore things like sounds and textures.
At the same time,they develop motor skills.But this apparent play is laying the groundwork for the later math and language work.
Now let's take a look at the materials called brown stairs.
For a young child playing with this graduated blocks,these brown stairs,they are not just a sensorial lesson.
By manipulating them,the child develops fine motor skills and by sorting and classifying them by size,by weight,the child learns some basic mathematics.
Similarly,with practical-life quipment,the child can learn how to button a shirt,cut up an apple for a snack and other real-world tasks.
Without this integration in real-world learning, is there any room for creativity?
Is creativity encouraged?
Well, Montessori teachers wouldn't praise a child for using a violin as a baseball bat or for putting their head like a hat.
But actually, creativity comes through learning to play the violin, using the object for the purpose that was intended and practical life exercises stress that."
L49C2
"Listen to a conversation between a student and a professor.Oh, Hi.Melanie.How are you doing?
I'm good.Thanks.
I just have some questions about this paper for your class.
Do you have a second to talk about it now?
Oh,yes.No problem.
I have about twenty minutes before my next class.
Will that be enough time?
Yeah.I think so.
Okay.So the thing is,you know,okay,I'm writing my paper on the history of jazz in New York City.
All right.Well,that's a pretty broad subject.
Well,actually I'm focusing on a specific decade,the 50s and on...and I'm only doing it on a few specific artists.
Oh,okay.Because I was going to say that seemed a bit,uh,too ambitious for a ten-page paper.
Yeah.No.It's not the subject I'm having trouble with.
Actually the paper is practically writing itself.
I mean,I have got a lot to say and it's going pretty well.
The thing is,I have this idea that might make it better and I was wondering if there's any way I could get an extension.
I mean,I know it's due next week.Right?
That's right.On Monday.
But I don't understand.
It sounds like you are doing so well.
Why do you need more time?
Yeah.Well,I could write the paper as it is and turn it in on time and it would be fine.
But?
But I was just talking to one of my friends whose family has lived in New York forever!
And it turns out that her grandfather was actually there,in the period of jazz I'm writing about.
I mean,he was a jazz musician and he actually,like persanally,knew the artists I'm writing about.
You are kidding!That's a coincidence.
Yeah.I know.It's cool.Right?
So anyway,that's why I was wondering if I could get an extension because I thought it would be really great if I could like interview him for my paper.
Ah...
But I don't think I can meet with him antil early next week.So...
Ah,I see.Well.
It would certainly add a new dimension to your paper,wouldn't it?
Have you talked to this gentleman yet?
Uh,no.But I talked to my friend,just,you know,ran the idea past her and she said he would probably love to do it.
But you know,he is busy until next week.
Okay.Well,yeah,I think that in this case we can definitely extend your deadline until,that's say,Friday next week?
Okay.That would be great!
But just to be fair,why don't you turn in an outline of your paper on the due date?
The outline?Oh,that's no problem.
It's basically done except for the parts about the interview.
Oh,yeah.The interview.
Could you have the questions ready then too?
The ones you are planning on asking.
Sure!Yeah,I can do that too.
And then I'll expect the final draft next Friday.
Okay.Great.Thanks! "
L49L3
"Listen to part of a lecture in a biology class.Okay,so that's how the arctic ground squirrel's able to cope in this extreme environment.
Now let's talk about your reading assignment,about reindeer,also typically found in Siberia and other far northern regions.
Who would like to start off?Yes,Mike?
Well,for one thing,they've got thick hair all over their body,even on their noses.
Yes.They are very well insulated,and the thickness of their fur varies depending on the season.
Good.Yes?
Um...newborn reindeer are very adult-like,like they can stand as soon as they're born,
and by their second day they can already run as fast as a human.
Critical.Food is very scarce in far north so reindeer herds have to cover lots of ground every day.
And in the fall they might easily trek a thousand kilometers or more to get to their winter feeding site.
So if you are a newborn you've got to get up to speed fast.
Okay Other adaptations?
Also reindeer don't have to keep their legs as warm as their main body,so they don't have to use up as much energy keeping them warm.
Yes,so that means they can allocate less energy to heating their extremities and more energy to maintaining stable temperature in their body core where their vital organs are located.
And you know I don't think it is mentioned in your textbook,
but even different parts of a reindeers leg are adapted for optimal cold weather performance.
The fat in the lower part of their legs,the part that gets coldest,that fat has a different chemical structure from the fat in the upper parts of the leg.
So it doesn't get hard,even at temperatures down around freezing,it stays kind of gel-like,kind of oily.
Okay, good.What about food?
What do you remember about that?
Well,they are pretty flexible.
OK,can you explain that a little more?
Well,they can eat a lot of different kinds of plants,so that improves their chances of coming across something they can eat.
I think they said that they found that the reindeer in one herd had something like 37 different kinds of plants.
OK,yes.You've really done your reading.
And reindeer also eat a number of different plant species that most animals are not very interested in.
Which means?
They don't have a lot of competition when it comes to that food?
That's right.
In particular,your reading mentions lichens.
Lichens are plants you'll find growing on rocks in the far north,sometimes referred to as reindeer moss.
They look pretty basic you know,just a little moss on a rock.
But lichens are actually quite complex.
They are not just a single organism.
They're actually kind of combination of some sort of fungus and some sort of algae that lire together in a symbiotic relationship.
Anyway...Okay,reindeer,um,oh,oh yes,and one more thing about lichens.
They crank out a lot of chemicals,which is probably at least part of the reason why they are not considered all that tasty by most animals.
Anyway,does anyone remember what your reading said about them?
Yeah,somehow when reindeer eat lichens they're able to draw a lot more nutrients from them than other animals.
Like if a cow or a sheep eats lichens,they're only gonna get like half as much nutrition out af them as a reindeer would.
That's right,and in winter,lichens are crucial for reindeer because their supply energy,
but they don't have all the proteins and minerals the reindeer need.
Um,so when reindeer get to the end of the long winter they are often very thin with low levels of minerals.
In spring they have to eat different plants and replenish what they've lost over the winter,
so what reindeer have done is they've developed the ability to digest different plants in different seasons by adjusting the microbes in their digestive systems.
As you know microbes are micro-organisms like bacteria that help to digest or break down food.
Well, what's interesting about reindeer is that they change the proportion of different microbes in their digestive system.
So you, so the reindeer might have more one kind of microbe in winter to help digest plants it eats then;
and in summer, it would have more another kind of microbe to help digest summer plants.
That way, the reindeer get more nutrition out of food of different times of the year. "
L49L4
"Listen to part of a lecture in an archaeology class.So if I ask you what most archaeologists do with all those pieces of broken pottery they find at the excavation sites,
you'd probably say that they help establish the time period of the site.
Pretty obvious.Huh?
Pottery helps us order things in time to assign relative dates.
Basically,when we date pottery,we look at its frequency at a given site.
As you can probably surmise,styles of pottery vary over time,in terms of how they're made,
what they're made of and what they were used for.
So as archaeologists,we built up a picture,
a sequence of how pottery changed over time as well as how its popularity varied over time which we can tell by the frequency of a style at a site,
how many occurrences we find at a given site.
But pottery can provide evidence about a lot of things,not just dating evidence,not just evidence of the time period that pottery was created.
So there is also another type of evidence that we call distributional evidence.
OK,pottery is evidence of distribution.
It,pottery,provides evidence that trade took place.
Pots were traded for themselves or given as gifts,
but even more often they changed hands cause they were used as containers for food or wine.
To fully understand how pottery's used as distributional evidence,
we have to know its origin,where it was made.
So how do we figure this out?
Well,by studying what the pottery's made of you look at the material that...that a pot's made of to know where it was made and its distribution.
OK.A third kind of evidence is evidence of function,
the function of the site where the pottery was found and sometimes about the lives of the people who lived there.
Now this evidence is a bit tougher to interpret than the other two.
And there are several reasons for this.
First of all,pottery is usually not found in primary contexts,that is,it's often not found in the place where it was used.
Think about you average town dump,you know the place where everyone's unwanted stuff ends up,
can you imagine archaeologists a thousand years from now digging up a town dump and then using the items found there to get meaningful information about how the objects found there were used?
Probably not.
A second reason why function is harder to identify is that not all objects found in one spot can be assumed to have identical functions even if they look similar.
If you come across a collection of pots at a site,
you need to work at the level of the group rather than the individual pots because you can't assume that they all have the same function just because they were found in the same place.
So this is where pottery's form comes into play.
The form of a pot can give us same ideas about its function,the suitability of the pattery to serve a specific function.
However,we have to be careful when it comes to skeuomorphs.
These objects are copies of the designs of other objects,but in another material.
And this can be problematic,because sometimes the new or different material is not well suited to the design.
A good example of this comes from a fifteen-century Dutch ceramics, a bronze cauldron was copied in ceramic, including the sort of big angled handles, and while it worked well in bronze, it didn't work in the ceramic skeuomorph.
Well, because the ceramic handles couldn't support the weight of the pot when it's full. It just couldn't function as it was intended to. "
L50C1
"Listen to a conversation between a student and a political science professor.I was elected to the student government this year.
Oh, congratulations! I was in student government myself as an undergraduate.
It taught me a lot about the political process. In fact, the experience solved my problem of what to do with my life.
It really cemented my interest in becoming a political scientist.
Cool! Anyway, the reason I came by is we are getting ready to conduct a straw poll on campus,
you know, hold an informal ballot since the general election is just a couple of months away.
We want to get a field from the students' bodies political leanings, like who students are planning to vote for, which political party people identify with, that sort of thing.
I'm sure. I help students run the straw poll once years ago, uh, it was a lot of work.
Mostly because we use paper ballots, and stayed up all night counting them. But if you use computers……
Yeah, we are creating a website for our students to be able to vote online.
Em, we are looking for a faculty advisor to help, actually. I was hoping you might be interested in.
Oh, I'm flattered, John. But my schedule is so jammed. I'm teaching two seminars, your intro-course, finishing up my research.But, what about Professor Clan?
She is new in our department. Plus, she is a wiz with computers.
Ok, I will ask her.
So, have you decided on the topic for your term paper yet?
Not really.
Why not write about your straw poll? Since the paper is not due till after the election, you could include your results.
Maybe compare them with the real election results.
But would that be enough? I mean, just comparing numbers?
Well, no, you need to provide some analysis, too. But I was thinking, there is a couple of local ballot questions this year.
You know, referenda, the voters can either support or not support?
Right. There is one on whether to ban smoking in restaurants, and another one……I think is whether to spend tax dollars for a new sports arena in the city.
Ah, Ok. Here is an idea. In regular elections, the vast majority of voters ignore referenda.
They vote for their favorite candidates but avoid ballot questions.
We believe it's because voters aren't familiar with the questions or don't understand them.
But actively educating people on ballot questions right before they vote can improve referendum participation rates.
In that case, maybe we could have our straw poll website providing information on the ballot questions, like how each proposal would affect students.
Exactly. And when you write your paper, you could compare the students' referendum voting rate to the general publics.
And include you own analysis of the results. Plus, there is plenty of publish research on referendum voting behavior.
Thanks, Professor Miller. I have no idea the straw poll can actually help me in my course work. "
L50L1
"Listen to part of a lecture in an ancient history class.Ok, last time we were discussing trade and commerce during the Bronze Age.
And I said a little over three thousand years ago, there was quite a lively trade among the countries along the Mediterranean Sea.
People are making objects out of bronzes and they were using bronze tools to make other goods.
And they develop trade networks to trade these goods with other countries around the Mediterranean.
One of the things they traded was glass.
And recently there was an archeological excavation in Egypt, on the Nile River around where enters the Mediterranean Sea where they discovered an ancient glass factory. Robert?
I thought our textbook said the Egyptians imported their glass from other countries.
Well, until now that’s what the evidence seemed to suggest.
I mean, we have some evidence that suggested that the Egyptians were making glass objects, but not glass.
Ok. Am……Am I missing something? They are making glass but they are not making glass?
I said they were making glass objects, right?
You see, it was previously thought that they weren’t actually making the raw glass itself that they were importing unfinished glass from Mesopotamia, which today is a region consisting of Iraq and parts of Syria and Turkey and Iran, and simply reworking it.
Most archeologists believed that the glass factories were in Mesopotamia because that’s where the oldest known glass remains come from.
You see, there was two stages of glass making.
The primary production stage where they made disks of raw glass.
And there was the secondary stage where they melted the raw glass, the glass disks, and created decorative objects, so, or whatever.
And from this new Egyptians’ site, we learned that the primary production stage had several steps.
First they took quartz, a colorless transparent mineral and crushed it.
Then they took that crushed quartz and mixed it with plant ash.
A plant ash is just what it sounds like, the ashes left after you burnt plant material.
They slowly heated this mixture at a relatively low temperature in small vessels, containers like jars made out of clay.
And that yielded a kind of glassy material.
They took this glassy material and grounded it up into a powder and then they used metallic dye to color it.
After that, they poured the colored powder out into disk-shaped molds and heated it up to very high temperatures.
So that it melted. After cooled, they break the molds, and inside there were the glass disks.
These disks were shipped out to other sites within Egypt and places around the Mediterranean.
Then in the secondary phase, the disks were reheated, and shaped into decorative objects. Susan?
So what kind of objects were people making back then?
Well, the most common objects we found, mostly in Egypt and Mesopotamia, the most common objects were beads.
One thing the Egyptian were very very good at was imitating precious stones.
They created some beads that look so much like emeralds and pearls that was very difficult to distinguish them from the real thing.
Em, and……and also beautiful vessels, ah, with narrow necks.
They were probably really valuable so they wouldn’t have been used to hold cooking oil or common food items.
They were most likely used for expensive liquids, like perfume.
Now the glass made at this factory was mostly red, to get this red color they used copper, in a sophisticated process.
Of course, any kind of glass was very valuable so these red bottles would only have been owned by wealthy people.
In fact, because it was so difficult to make, and sort of mysterious and complicated, it was probably a product produced for the royal family.
And they probably used glass to show their power.
Also, beautiful expensive objects made great gifts if you are looking to establish or strength the political alliances.
And it is quite possible that the ancient Egyptians were actually exporting glass, not just making it or importing it.
The trade with Mesopotamia was probably a friendly mutual trade because a Mesopotamia glass was usually white or yellow.
So Mesopotamians might accept something like, we will give you two white disks for two red disks. There is no proof of that, at least not yet. "
L50L2
"Listen to part of a lecture in a biology class.Processor: Ok. There are two major types of classifiers in the world, people we call lumpers and people we call splitters.
A lumper is someone who tries to put as many things as possible in one category.
Splitters like to work for the differences and put things in as many different categories as possible.
Both lumpers and splitters work in the business of defining biological classifications.
The great philosopher Aristotle is generally considered the first person to systematically categorize things.
He divided all living things into two groups. They were either animal or vegetable.
And these categories are what biologists came to call “kingdoms”.
So if it ran around, it was an animal, a member of the animal kingdom.
And if it stood still, and grew in the soil, it was a plant, a member of the plant kingdom.
This system, organizing all life into these two kingdoms, worked very well for quite a while, even into the age of the microscope.
With the invention of the microscope, in the late 1500s, we discovered the first microorganisms.
We thought that some wiggled and moved around and others were green and just sat there.
So the ones that moved like animals were classified as animals, and the more plant-like ones as plants.
Oh, before I go on I must mention Carolus Linnaeus.
A hundred years or so after the invention of the microscope, Carolus Linnaeus devised a simple and practical system for classifying living things, according to the ranks of categorization still in use today——class, order, family and so on.
And by far the best aspect of the Linnaeus system, is the general use of binomial nomenclature, having just two names to describe any living organism.
This replaced the use of long descriptive names, as well as common names which vary from place to place and language to language.
Binomial nomenclature gives every species a unique and stable two-word name, agreed upon by biologists worldwide.
But not everything about this system remained unchanged.
Take for example the mushroom, a fungus.
It grew up from the ground and looked like a plant. So it was classified as a plant.
But using the microscope we discovered that a fungus contains these microscopic thread-like cells that run all over the place.
And so it’s actually not that plant-like. So in this case, the splitters eventually won, and got a third kingdom just for the fungus.
And as microscopes improved, we discovered some microorganisms that were incredibly small. I’m talking about bacteria.
And we could see that they didn’t have what we call a nucleus. So they got their own kingdom, a kingdom of very tiny things without nucleoli.
So then we had several kingdoms for plants and for animals, and the different kinds of fungus like mushrooms, and for these tiny bacteria.
But we also had some other microorganisms that didn’t fit anywhere. So biologist gave them their own kingdom.
And this fifth kingdom was sort of anything that doesn’t fit in the first four kingdom, which upset some people.
And then there was a question of viruses. Viruses have some characteristics of life but don’t reproduce on their own or use energy.
So we still don’t know what to do with them. The lumpers want to keep viruses in the current system.
Some of the splitters say to give them a separate kingdom.
And the extreme splitters say that viruses have nothing at all to do with living things and keep them out of my department.
Recent research though has moved to see yet another direction.
Nowadays when we want to determine the characteristics of something, we look at its biochemistry and its genetic material.
And what we’ve discovered is that some bacteria are not like the others.
Many of these are called extremophiles.
They live in very strange places, in polar ice or in a boiling water of hot springs or in water so salty (that) other organisms couldn’t live there.
Extremophiles tend to have a different chemistry from other bacteria, a chemistry that in some case is actually more related to plants and animals than to previously known bacteria.
So what to do with this strange bacteria?
Well, one thing we’ve done is creating a new set of categories, the domains, overarching the different kingdoms. Biologists now recognize three domains.
But even as we talk about these new domains, well, come back in a few years and it might all be different. "
L50C2
"Listen to a conversation between a student and the head of building maintenance.Can I help you?
Yeah, I um……I’m taking summer classes right now and they put me in Robert’s Dormitory, offered by the library.
Ok.
And I guess they are painting the library or doing something to the outside of the building?
Ah……yes, they are. They are replacing the bricks on the outside walls.
Well, whatever it is, it’s like……really disturbing, for those of us with windows facing the library.
They are working on the wall right opposite us. I mean, dust is everywhere coming in the windows, and, the noise, cos we are like…… what, ten feet away.
And……well, it is just not a pretty picture.
Right, well, that’s why we waited until now to start work on it. I mean, most students have already left campus for summer vacation.
Yeah, but Robert’s Hall has been used by all the summer students.
Really? The housing didn’t notify us of that.
Yeah. It’s pretty full. I mean, I can’t sleep at night, because of the smell and the dust and……
You know, I’d love to just like close the windows but you know (it’s) being summer now.
Yes, I know. There is no air-conditioning in that building.
Right! So I mean, we got five more weeks of classes left, and we were really wondering how much longer they are going to be working on that particular wall.
Because maybe it’s going to be a while.Do you think they could maybe work on a different side of the building for now, one that's not facing people’s dorm rooms, and wait until the students are gone?
To come back and finish this side?
I mean, that way the dust and noise won’t be coming directly into our windows while we are here.
You know, I wish it weren’t being done this way and it doesn’t make sense.
But……this particular decision was made by a special committee and their plan was finalized several months ago.
They just didn’t realize there would be students in Robert’s Hall now.
Yeah.
Plus, well, the equipment is all set up, you know, the scaffolding is up on that side of the building and……
oh it just won’t be practical to have the construction workers move everything to another side and leave a whole side of the library all torn out like that.
I guess not. Isn’t there another dorm open anywhere?
Not that I know. Oh, wait. I overheard someone saying today that Manchester Hall isn’t being used by the city’s summer camp after all.
You know, most years they house their participants in that dorm all summer.
Well, there is an idea.
Now it’s a smaller dorm and it’s a little out of the way but……well, I bet……I bet they could move the affected student from Robert’s Hall.
Wow, I think a lot of people would definitely appreciate that.
Ok, well, let me call the housing people and I will get back to you. Leave your name and number, ok? And I will let you know what I find out.
Great. Thanks. "
L50L3
"Listen to part of a lecture in the United States' Literature class. The professor is discussing Realism.Professor: Ok, everyone. In our last class, we finished up Romanticism, right?
So now let's look at something completely different.
Realism as a literary technic was most popular in U.S. literature from around 1860 till 1890.
So it started pretty much around the time of the civil war.
And I think you'll see right away how it is different from Romanticism or any other kind of literature.
There is a very specific point that makes it unique.
And that is that it shows people as they are and get you to look at them and also you know the things that need to be changed in the society.
And it doesn't without being sentimental, not in that sort of over-emotional way, the way that romantic literature can.
Realism tells it like it is.
Let's look society as a whole.
In the late 1800s, people were interested in the scientific method as well as rational philosophy, which says that people can discover the truth by using reason and factual analysis.
So reason and facts, ok.
And at the same time that realism was becoming popular, there were a lot of political and socioeconomic changes happening in the country.
There was increased literacy, plus the growth of industrialism and urbanization, growth in population from immigration, and a rise in middle class affluence.
All these factors combined with the importance of reason and facts, meant readers were interested in really having a good understanding of all these changes, the changes going on in society.
A scourer named Amy Chaplin says, and I'm just paraphrasing here, that Realism is a way to understand and deal with social change, which makes a lot of sense I think.
So then, let's take a closer look at the trips of the trend, and how realist writers did their work.
For one thing as we said, they focus on, express reality, and in great detail.They inferred verisimilitude. Shall I write down on board?
Students: Um-hum.
Professor: Ok. Verisimilitude means basically the same true or real, like say, a photograph rather than a painting in a way.
In fact, that's a good analogy. You see writers try to capture a moment in time and all its basic facts but without exaggeration, just like a camera does.
Anyway, the events, the things that happen in realistic literature are usually pretty much plausible.
I mean, you figure that they can probably happen to anyone.
And the characters are believable, too.
And actually, they are usually even more important than the plot.
There're also……they talked the way the real people talk, authentic speaking styles from different regions, different parts of the country were captured in the text. Does that make sense? Ok.
So, besides verisimilitude, another important characteristic of realism is the narrator's objectivity.
Characters in the events were described without the narrator passing much judgment on them or anything or being too dramatic.
Basically, you are reading a story without too much extra comment from the narrator.
Ok, now we have an idea of what realism was.
So, who were the players? Well, two important realist novelists were Rebecca Harding Davis and Mark Twain.
We'll talk more about other realists tomorrow.But for today, let's just start by looking briefly at these two.
Rebecca Harding Davis was an author and journalist who, like other realists, was concerned about all those social changes going on.
She wrote mainly about some marginalized groups of the time, like women, native Americans, ah, immigrants.
Now her best known book is a novella called The Life in the Iron Mills.
It's really a key text, because it's one of the original realist works.
Her works overall have been pretty much ignored for a long time.
But some critics and scourers are starting to revisit them and study them more seriously.
Probably more from the historical aspects of the works and……but I think that's great.
But if we are talking about great literature, literature that's read and enjoyed today as something more than just a way of looking at that era, the era when that was written.
Well, a favorite of mine is Mark Twain.
I'm sure you have read or heard of his most famous book, The Adventures of Huckleberry Finn.
And Twain's style, he goes back to what I said earlier, verisimilitude, the realistic way characters act and talk.
You should realize too that this was quite a contrast to earlier writers in the U.S., who try to emulate the British writers, try to be very elegant, at the expense of Realism.
You know, a lot of critics will tell you that American literature began with that book, The Adventures of Huckleberry Finn. "
L50L4
"Listen to part of a lecture in a geology class.Professor: Hi, class, let’s get started.
Um, last time we finished up the section of coal, so we have just two fossil fuels left to talk about. Those are petroleum and natural gas.
Today I will concentrate on petroleum and we will get into natural gas tomorrow.
Like coal and natural gas, petroleum has been formed over millions of years, from remains of prehistoric plants and animals.
And like coal and natural gas, it’s found in the rocks of Earth’s crusts. In fact, the word “petroleum” literally means “rock oil”.
And in its’ original state, the way we find it in Earth’s crust, it is called crude oil, sometime people will short it up, and just refer to it as crude.
Um, petroleum also contains natural gas, so usually the petroleum industry is naturally searching for and utilizing deposits of both crude oil and natural gas at the same time.
In other words, companies might as well gather, use and sell both the oil and the gas when they find it, since both are valuable. And……
Student: But what kind of organic materials, I mean, specifically what kind of dead plant and animals make up petroleum exactly? Do you mean like trees and dinosaurs?
Professor: Well, apparently petroleum is usually made from simple, one-celled marine animals and plants, algae, for example.
Um, what happens is this accumulated plant and animal material that originally came from the ocean gets covered by sediment.
And then is…um, eventually exposed to earth internal heat and pressure, for millions of years.
And over those millions of years, the heat cooks and the pressure molds that material, turning it into a thick, sticky liquid.
And since petroleum is made from these ocean organisms, you can guess where it was found, it makes sense that we usually find it under the ocean or near shore, right? Yes, Ann?
Ann: I’ve heard people talk of……ah……live and dead oils?
Professor: Well, um, when crude oil has a lot of natural gas mixed up with it, it’s called live oil.
But if the gas escapes from the mixture, then oil is said to be dead. And it’s heavy and more difficult to pump.
Does anyone know how the gas separates from the oil? Sam, go ahead.
Sam: Doesn’t it happen when the oil shoots up to the surface?
Professor: Yes, that’s right. When oil reaches the surface of the Earth, there is less pressure on it.
And with less pressure, the oil and gas were able to separate. The other way the crude oil was able to come up to the surface is by people pumping it up out of the ground.
And, um, it’s the same thing that happens at the surface, there is less pressure, and, so the oil and gas separate.
But when we talked about how would actually exists inside earth’s crust, most people think that there are huge, pools of oil sitting around in caverns somewhere under there.
That’s really rare. The majority of petroleum is just filling in the tiny pores and cracks in rocks.
Now, um, a little more on the petroleum industry.
As far as the extraction process the petroleum industry digs deep wells to reach underground oil fields where crude oil has accumulated over a large area and extract between layers of rocks.
Then it pumps the crude oil out. Then its refineries have two main tasks, convert less valuable crude oil into a more valuable form and create usable products from refined oil.
Basically, the refiner will do this by boiling the oil.
When the oil cools off, the stuff that is left is turned into a variety of products, like gasoline, diesel fuel for cars and trucks, asphalt for roads, um, paints, plastics, even soaps.
And check what you’re wearing, if you are wearing something with synthetic fibers, what that really means is that it is made of the petroleum. So you can see petroleum is essential to today’s industrial society.
Now, next week we will be joined the graduate students from the department of petroleum engineering to examine the comprehensive field study they’re working on in our local oil fields.
And I’d like you to read over the pack of information I’m about to hand out to you before we go. It should familiarize you with the history of the oil field we will be touring as well as the details of their project. "
L51C1
"Listen to part of a conversation between a student and her biology professor.Professor：So, the assignment is to reproduce one of the animal camouflage experiments we read about in our textbook. Which experiment did you pick?
Student:Well, I was wondering if I can try to reproduce an experiment that’s……kind of the opposite of what was discussed in the textbook?
Professor:So instead of how and why an animal might hide itself, you want to do something about why an animal might want to be seen? Em? Tell me more.
Student:Well, I got the idea from one of the journals you said we should look at. It’s an experiment about ah……they called them eyes bugs in the article?
Professor:Eyes bugs, sure. The patterns on the wings of moths and butterflies that are generally believed to scare off predators because they look like big eyes?
Student:Yeah. Except the article was about the experiment that disputes that theory.
Professor:Well, we know that the markings do scare the birds but the idea that the spots looked like eyes is……well, that is just a commonly held belief.
Student:So, that’s not even based on research?
Professor:Well, this whole idea of moths and butterfly markings being scary because they looked like eyes, rest on how we imagine the predators, like birds, perceive the markings. And we can never really know that. All we can do is observe bird behavior. But tell me more about the experiment.
Student:Ok. It said the experiment looked at the shapes of the markings on moths’ wings. The researchers wanted to know if the markings that were round and eye-shaped were more effective in deterring predators than square and rectangular markings.
Professor:Ok.
Student:Yeah. So they attached food to paper models of moths with different shaped marks drawn on the wings to see how birds reacted. And what’s interesting is they realized the round marks were not more effective in scaring bird than other shapes.
Professor:Were they less effective?
Student:No, they were about the same. But what researchers did determine is that larger markings were more effective than smaller markings in scaring off prey. They call this phenomenon “visual aliveness”.
Professor:Visual aliveness. Um. Well, I guess that it is not all that shocking if you think about it.
Student:So anyway, is it ok? Can I repeat this experiment and write about it?
Professor:Yes, I think that’ll work. The problem I proceed is……well……where? This is an urban campus, you’ll have a hard time finding a good place to set up the experiment.
Student:Oh, I wasn’t planning on doing it on campus. I’m going home for spring break and my family lives in the country, far from the near city. I can set it up in the backyard.
Professor:Good idea. Except one week is not a lot of time, so you will need to make some adjustments to have enough data. I’d set up the experiment near bird feeder and get in as much observation time as you can. "
L51L1
"Listen to part of a lecture in a botany class.Professor:So, continuing with crop domestication and corn, or, um, maize as is often called, obviously it’s one of the world’s most important crops today.
It’s such a big part of the diet in so many countries and it’s got so many different uses that it’s hard to imagine a world without it.
But because it doesn’t grow naturally, without human cultivation, and because there’s no obvious wild relative of maize, um, well, for the longest time researchers weren’t able to find any clear link between maize and other living plants.
And that’s made it hard for them to trace the history of maize.
Now, scientific theories about the origins of maize first started coming out in the 1930s, one involved a plant called teosinte.
Teosinte is a tall grass that grows wild in certain parts of Mexico and Guatemala.
When researchers first started looking at wild teosinte plants, they thought there was a chance that the two plants, um, maize and teosinte, were related.
The young wild teosinte plant looks a lot like the corn plant.
And the plants continue to resemble each other, at least superficially, even when they’re developed.
But when the scientists examined the fruits of the two plants, it was a different story.
When you look at right corn, you see roll upon roll of juicy kernels, um, all those tiny little yellow squares that people eat.
Fully-grown teosinte, on the other hand, has a skinny stock that holds only a dozen or so kernels behind a hard, um, almost a stone-like casing.
In fact, based on the appearance of its fruit, teosinte was initially considered to be a closer relative to rice than to maize.
But there was one geneticist, named George Beadle, who didn’t give up so easily on the idea that teosinte might be, well, the parent of corn.
While still a student in the 1930s, Beadle actually found that the two plants have very similar chromosomes, very similar genetic information.
In fact, he was even able to make fertile hybrids between the two plants.
In hybridization you remember, the genes of two species of plants are mixed to produce a new third plant, a hybrid.
And if this offspring, this hybrid, is fertile, then that suggests that the two species are closely related genetically.
This new hybrid plant looked like an intermediate, right between maize and teosinte.
So Beadle concluded that maize must have been developed over many years, ah, that is a domesticated form of teosinte.
Many experts in the scientific community, however, remained unconvinced by his conclusions.
They believed that with so many apparent differences between the two plants, it would have been unlikely that ancient, the pre-historic peoples could have domesticated maize from teosinte.
I mean, when you think about it, these people lived in small groups, and they had to be on the move constantly as the seasons changed.
So for them to selectively breed, to have the patience to be able to pick out just the right plants and gradually over generations, separate out the durable nutritious maize plant from the brittle teosinte that easily broke apart, it’s a pretty impressive feat.
And you can easily see why so many experts would have been skeptical.
But as it turns out, Beadle found even more evidence for his theory when he continued his experiments, producing new hybrids, to investigate the genetic relationship between teosinte and maize.
Through these successful experiments, he calculated that only about 5 specific genes were responsible for the main differences between teosinte and maize.
The plants were otherwise surprisingly similar, genetically.
And more recently, botanists have used modern DNA testing to scan plant samples collected from throughout the western hemisphere.
This has allowed them to pinpoint where the domestication of maize most likely took place.
And their research took them to a particular river valley in southern Mexico.
They’ve also been able to estimate that the domestication of maize most likely occurred about 9000 years ago.
And subsequent archaeological digs have confirmed this estimate.
In one site, archaeologists uncovered a set of tools that were nearly 9000 years old.
And these tools were covered with a dusty residue, a residue of maize as it turns out.
Thus making them the oldest physical evidence of maize that we found so far. "
L51L2
"Listen to part of a lecture in a world history class.professor:So one of the more common topics that comes up in world history because it's had a pretty dramatic effect on how different societies evolved over long periods of time is cultural diffusion.
Now, cultural diffusion is generally defined as the transmission of culture from one society to another.And by culture, we mean anything from artistic styles to......um......you know, technology, science.
So we use culture very broadly.
A common means of this process taking place is trade, travelling merchants or trading hubs, places where people from various areas all come together and ideas get exchanged.
Let's start with the example of the transmission of a number system, a system that used the number Zero, from South Asia into Western Europe.
Ok, so before this cultural diffusion happened, the dominant number system in Western Europe was the Roman Numeral System.
The Roman Numeral System developed primarily as a means of record-keeping, as a way to keep track of commercial transactions, um, taxes, censors' records, things of that sort.
As a consequence, this system started with the number One.
Student:With One? Not with Zero?
Professor:Right. See in Roman Numerals, Zero isn't really a value in and out itself.
It wasn't used independently as a number on its own.If your primary concerns just basic types of record-keeping......
Student:Oh, yeah. I guess you wouldn't need a Zero to count livestock.
Professor:Or to keep track of grain production or do a census.
And it wasn't an impediment as far as sort of basic engineering was concerned either, um, to their ability to construct buildings, roads, stuff like that.
But other number systems developed in Asia, systems that do incorporate Zero.
The mathematics these societies developed included things like negative numbers.
So you start to get more sophisticated levels of mathematics.
So one of the earliest written text sub mathematics, that has Zero, negative numbers, even some sort of basic algebra, is written in South Asia in the early 7th century.
This text makes its way into the Middle East, to Baghdad.And it's eventually translated into Arabic by a Persian astronomer and mathematician.
Once he began his translation, he quickly realizes the advantage of this system, the types of math that can be done.
Soon, the text begins to be more widely circulated through the Middle East.
And other mathematicians start to advocate using this number system.So by the 10th century, it's the dominant system in the Middle East.
And as a consequence, algebra and other more sophisticated forms of mathematics start to flourish.
Meanwhile, in Western Europe, the Roman Numeral System, a system without Zero, was still in place.
In the late 12th century, an Italian Mathematician named Fibonacci was travelling in North Africa along with his father, a merchant.
And while he's there, Fibonacci discovers this Arabic text.
He translates the text into Latin, and returns to Europe.
And he promotes the adoption of this number system because of the advantages in recording commercial transactions, calculating interests, things of that nature.
Within the next century and the half, that becomes the accepted dominant number system in Western Europe.Any questions? Robert?
Robert:Um, this Fibonacci, is he the same guy who invented that......um.......that series of numbers?
Professor:Ah......yes. The famous Fibonacci sequence.Although he didn't actually invent it, it was just an example that had been used in your original text.
I mean, can you imagine?
Introducing the concept of Zero to Western Europe?And this is what you go down in history for?Carol?
Carol:So, do we see like an actual change in everyday life in Europe after the Zero comes in?
Or they really just......
Professor:Well, where the change takes place is in the development of sciences.
Carol:Oh.
Professor:Even in basic engineering.
It isn't a radical change.
Um, but as you start to get into, again, the theoretical sciences, ah, higher forms of mathematics, calculus, Zero had a much bigger influence in their development.
Ok, now note that as cultural diffusion goes, this was a relatively slow instance.
Some things tend to spread much quicker, um, for example, artistic, or architectural styles, such as domes used in architecture.
We see evidence of that being diffused relatively quickly from Rome to the Middle East to South Asia...... "
L51C2
"Listen to a conversation between a student and the director of the Student Activity Center.Director:Hello, Jack. Is everything set for the trip this Saturday?
Student:Everything’s ready. Ah, fifteen people have signed up. Our train gets into New York City at noon which leaves plenty of time to get downtown to the art gallery for the reception.
Director:It’s great. You could organize this. What an honor having a painting by one of our students in that exhibit!
Student:Yeah. My roommate’s so modest. If we weren’t such good friends, I’d never realize that his work was being exhibited. So, since I was going anyway for the opening and all, I figure that might as well make a student event out of it. Working here at the Student Event Centers made me realize how popular our activities are. I figure they’ll be interested in it.
Director:Well you've done a super job organizing everything. This poster was great. And they were up in no time.
Student:Thanks. And I’m glad you could approve the funding for us.
Director:My pleasure. By the way, how are you getting to the gallery from the train’s station?
Student:Well, there are buses that run downtown.
Director:Right. You grew up in New York City, didn’t you?
Student:Yeah. But, the bus, well, that’s kind of what I want to talk to you about.
Director:Yes.
Student:I realized that at the last minute, but, well, the weather for Saturday is supposed to be really nice, sunny, warm. It’ll be a great opportunity to walk the High Line.
Director:The……what?
Student:Haven’t you?......Oh, I guess not everyone has heard of it. It’s this amazing……it’s like this park in the sky.
Director:A park in the sky?
Student:Yeah. Well, see there was this old train line. You know one of those elevated lines, the kind that run high above the streets?
Director:OK.
Student:Well, this one was used for freight, not passengers.
Director:Aha.
Student:But when it got cheaper to move freight by trucks, they stop using it. It was abandoned for a long time. And then, a few years back, the city agreed to turn the tracks and the surrounding area into a park. It’s not very wide but it’s over a mile long. And it goes from the train station all the way downtown near the gallery.I’ve walked before, it’s really cool.There was grass and flowers everywhere, and since you’re high up, you get these great views of the city.
Director:Sounds wonderful. But have you considered not everybody might be interested in walking that far? They might prefer the bus.
Student:Couldn’t we just split up?You know how some of us walk and the others take the bus?
Director:But remember, Jack, the poster advertises you as the tour leader, not everybody sees the adventure about getting around the city.You need to find someone to accompany people on the bus, then you take the walkers.
Student:Yeah. But who? Um, the trip’s in two days.
Director:Well, I did my graduate work in New York, of course it was a while ago, but I still know how to get around the city.
Student:Yeah……
Director:And I’d love to see that exhibit.
Student:You’d go? Ah, that’ll be great! "
L51L3
"Listen to part of a lecture in an art history class.The professor has been discussing illustrated books.Professor:I want to take a look one particular book to give you an idea about what was involved in publishing illustrated books in the 1800s.
The book’s called The Birds of the America and the illustrator was John James Audubon.
So,The Birds of the America, four volumes which contained illustrations of nearly every bird in the United States, over 400 birds, all hand-colored, all painted life-sized, the largest birds painted on the largest printing paper available at that time.
This required a lot of dedication.
And Audubon is best remembered as an incredibly meticulous accurate artist, a very accomplished illustrator of the natural world.
And while there were other artists working on the similar project at the same time, Audubon’s book remains the most well-known and successful of its kind.
But, let’s talk a bit about Audubon himself first.
First of all, Audubon was not a traditional painter.
And by this I mean that he didn’t work in oils.
He preferred to use water color and pastel crayons.
And he worked on paper instead of on canvas.
The thing is, Audubon considered the illustrations in his book, not the original water colors, to be his finished product.
His water colors were merely preparatory studies, most of which were painted while he was observing birds in the wild.
These water colors were then sent to his printer who created the final prints for the book.
And Audubon was so concerned with accuracy that he often scribbled notes to the printer around the edges of these original water colors.
In fact, you might question whether producing a work of art was even Audubon’s goal.
Now, when I look at Audubon’s illustrations, I see a work of art.
But, it may make more sense to consider Audubon, first and foremost, as a naturalist, as a scientist.
See, the early 19th century when Audubon was painting was a time of major scientific inquiry.
And an essential way of spreading scientific knowledge was through those illustrated books.
Student:So what did Audubon consider himself? An artist or a scientist?
Professor:I’m not sure the distinction between the two was all that clear in the 1800s.
I think we can accurately state that the driving force in his art was getting the science right.
And this was perhaps a point that critics of his art work at that time just didn’t appreciate.
Audubon also study birds in ways that didn’t directly inform his art.
Ah, you know what bird banding is right? A bird has a band attached to its foot so we can learn about things like migration patterns.
Well, the first recorded instance of anyone doing that, it was Audubon.
Another example, a common belief of that time was that vultures used their sense of smell to find food.
Audubon didn’t believe that.
So, he tested it.
He put a large painting of a dead sheep in a field, and sure enough, vultures found it and started pecking at it.
Now, Audubon’s work was very accurate, and we know this because we can compare his illustrations to the birds around us.
But sometimes it’s not possible to check.
There are actually several birds in his book that no one’s ever seen.
These are sometimes called Audubon’s mystery birds, because even though he drew them, there is no evidence that they exist in the wild.
For someone who’s respected as a naturalist, isn’t it strange to think that he drew some birds that don’t appear to be real? For example, there is an illustration that appears to be a type of warbler, a small bird.
It has a white ring around its eyes and white bars on its wings.
No one’s ever seen a warbler like this, so some people wonder if Audubon maybe forgot certain details about this bird when he painted it, or that he copied another artist’s work.
But considering that Audubon was such a meticulous artist, well, that might be a better answer.
Hybridization is something that’s well-known in birds.
And it definitely explains the rather unique-looking duck Audubon painted.
He himself suggested that maybe it wasn’t an unknown species but a hybrid, born from two different species.
Since then, this particular crossing species has actually been recorded, both in the wild and in captivity.
So it turns out that Audubon was right.
And this duck actually was a hybrid. "
L51L4
"Listen to part of a discussion in a history of science class.The class is discussing the heliocentric theory.Male Student:What I found really difficult to understand is why the heliocentric theory, um, why wasn't like believed by everybody right away?
Professor:Well, one thing that's hard to do is to sort of see things from the perspective of someone who's hearing that theory for the first time.
I mean today we tend to assume that the moment the heliocentric theory was laid out, the idea that the Sun, not the Earth, was the center of the solar system, that you know, you'd have to be in denial, not to accept it.
But it really wasn't that easy.
Male Student:But the idea that the earth wasn't the center of the universe……that has been tossed around for like centuries, right? I mean, lots of people would have the idea.
Professor:Yes, that's true, going all the way back to the Ancient Greeks.
But in Europe, when Galileo championed it in the 17th century, during part of his discoveries using a telescope, there still was some major resistance to it.
Male Student:But I still don't understand why, I mean, isn't it obvious?
Professor:Well, despite Galileo's ingenious arguments in support of the heliocentric theory, there was still a lot of reasons why people of that period couldn't buy into it.
Remember, we are talking about four hundred years ago, so ah, let's think about a few of those reasons, Ok?
So, first of all, they could work out that if the Earth was going around the Sun, then it had to be traveling at many thousands of kilometers per hour.
And that was just beyond anything anyone could understand.
You know, they could understand riding a horse or walking, maybe they could get up to 30, 32 kilometers per hour.
But tens of thousands of kilometers per hour? That was just crazy.
So, to many people, whatever is going on, it couldn't be that.
Female Student:Um… So people didn't believe the heliocentric theory because it was so hard to believe?
Professor:Exactly.
But, there were more scientific kinds of reactions as well.
Because, look, if you have ever been on a carousel or you are on a ride at an amusement park and you are on something that is going round round and round, two things, alright?
One, you know you are moving, there is no doubt.
And the other thing is, you know that unless you hold on tight, you are gonna go flying out because of centrifugal force, right?
Female Student:So, if I understand you for the average person 400 hundred years ago there was no evidence that we are moving at higher speed, right?Since everything was securely on the ground and no one was flying off into space?
Professor:Yes.
And in particular.
And this was one specific difficulty for people in the period, even if they thought that there was some sort of force that maybe kept you and me and buildings and things on the surface of the Earth.
Their theory about the nature of the atmosphere was that nothing was holding it down.
So if, if you can understand that way of thinking, then clearly, if the Earth, was moving at a great speed, we should've lost all our atmosphere a long time ago.
You know, it would be like, trailing away behind us.
And so, I want to try a little sort of experiment, because, I, I think that what we will find is that some of us have ideas about motion that actually fit with anti-heliocentrism.
Male Student:Anti-heliocentrism? No way.
It's the 21st century.
Professor:Well, then let's see.
So, picture the following.
You are at the equator, moving at 1600 kilometers per hour.
Ok? And you drop something, small and light, like a matchstick for example.
Where is it going to land?
Male Student:That's easy.
It will be long gone.
The matchstick is so light that it will fly right out of my hand and end up away behind me somewhere.
Professor:Ah, actually, that matchstick you dropped, it'll land right at your feet.
Male Student:What?
Professor:Well, let's think about it.
If I got to consider that the Earth's rotating at 1600 kilometer per hour at the equator, and you, me, the air, and that matchstick will all moving together at the same speed, even though it doesn't seem or look or feel like we are moving.
So class, clearly, even today, we actually have some inclination to think that if the Earth were moving around at a great speed, we all would see signs of it.
Perhaps now you are less inclined to dismiss those who once found heliocentrism so hard to believe.
Ok, let's move on. "
L52C1
"Listen to a conversation between a student and his creative writing professor.Professor: John, listen. I can clearly see that you put a lot of time into your response paper.
John: I did! It took me forever.
I rewrote it a dozen times.
Professor: And your hard work shows.
Unfortunately, it’s a week late.
John: I know. Sorry.
I just got a little behind, you know, sports and homework.
But I’m on top of things now.
Professor: Glad to hear it!
Now, as for our meeting today, I’d like to talk to all of my creative writing students one on one at least once during the term and see how they’re doing.
John: I think I’m doing OK. Busy, you know, but other than that…
Professor: Well, I found through the years that some of my assignments can be pretty tough for first year students like yourself, like the response paper you just did, the explication of a Pablo Neruda poem.
Emm…by the way, why did you choose ""The Lemon""?
It’s an unusual choice.
John: It was my favorite in the book of Neruda’s poems.
All the poems are about everyday objects and, you know, simple pleasures.
Professor: Right, Elemental Odes, one of my favorites.
John: I like how Neruda took things like fruit and vegetables and socks, and use metaphors and similes to describe them as these wonderful mysterious things, like in“The Lemon"".
He describes a lemon falling to Earth from the stars, and he compares a slice of lemon to a stained glass window.
It’s so original!
Professor: Beautiful images, aren’t they?
Neruda didn’t win the Nobel Prize for literature by accident.
John: No, he didn’t.
Professor: Now, as you know, the paper was only the first half of the assignment, and I’m concerned about your ability to complete the second part on time, considering how much time the first part took you.
John: Actually, I finished it just before I came here.
Professor: Excellent!
John: It was tricky, too.
You know, having to write a poem inspired by ""The Lemon"", but in a completely different style.
Professor: Right!
John: In order to do that, I really had to study Neruda’s style and read a lot of his stuff, which was great, but ""The Lemon"" is free verse.
So to do the assignment, I decided to use a strict meter - iambic pentameter, to be as different as possible.
Professor: So each line of your poem has ten syllables and every other syllable is stressed.
Interesting choice!
Iambic pentameter is certainly different from free verse.
John: It was hard for me though, because usually when I write a poem, I choose my own topic, and I just write.
I don’t worry about counting syllables or anything.
So, I’m kind of hoping we won’t have more assignments like this?
Professor: Sorry to disappoint you, but these assignments are designed to get you out of your comfort zone, to get you reading and writing a wide variety of poetic styles. "
L52L1
"Listen to part of a lecture in an art class.Professor:This week you are going to be studying something new, a painting in still-life.
First I want to give you a little background that might be helpful when you start working.
We spend a lot of time on portrays in this class and moving from painting people to painting objects, might feel like a big shift.
But I think it’s important for you to understand that you could pack just as much life and vibrancy and excitement into a painting of a bowl of fruit as you can into something more dynamic.
And, you know, still-lives don’t just need to be straightforward representations.
A lot of still-life painters really use the simplicity of the style to send a message or tell a story, even portrays sometimes include elements of still-life paintings.
For example, in a portray, there might be a map, hanging on the wall.
Or there might be some books on the table next to the subject.
These objects tell you something about the subject like maybe that person was well-educated.
A big part of still-life painting is the use of those kinds of symbols.
The objects you include can provide more context and help convey your message.
I’d also like to show everyone an example of still-life that we can talk about a little and use to get some inspiration.
This is by James Peale, one of the true masters of the art of still-life.
This piece is called Still-life, bowls, some apples and vegetables.
And it’s a really, really great example of what I’m going to be looking forward in your painting.
Now, Peale did his work in the early 19th century.
And painters of that period approached still-life painting from a scientific perspective.
Let’s look at this painting to help you understand what I mean.
See the red tomatoes in the foreground and how vibrate that color is?
And if you look at the large heads of cabbage farther back, every detail, every crinkle in each leaf, all the fruits, are so precise.
They are almost like a sketch you’d see in a field guide.
Peale and other painters of this era used still-life painting as a way of exploring the natural world and satisfying their curiosity about nature.
So now we can take some time to discuss a little more of… more about the… the actual process of still-life painting.
Now, before you paint a single stroke, you’ve got to plan the composition of your painting.
You know, the arrangement of the objects to make sure everything is set up the way you wanted.
I remember a still-life piece I painted when I was in university.
It was vegetables I think and I had created scratches of the setting.
But then I realized the arrangement of the vegetables in a basket just, just didn’t look right.
So I had to start over.
So I can say from experiment it’s really important to make sure your arrangement is just right before you even start painting.
Now, what are some ways to make sure the composition of your painting is the way you want it to be?
Well, it’s important in the still-life to make sure you’re not overdoing the amount of positive space, the amount of stuff in your piece.
The still-life really is not just about the subject matter.
If you make a really cluttered composition with too much going on, it can throw off your painting.
That’s something you notice in the James Peale painting.
Notice how it really… you know it makes great use of negative space, you can see how he sort of embraces those little empty spots on the table.
And that adds a really nice sense of balance.
Also, try to make your still-life look natural.
If it looks contrived and if it’s obvious a person deliberately arranged everything, it takes away from the simplicity and the natural feel of the work.
Basically the best still-life paintings are the ones where the objects don’t look arranged for the painting at all, but that those tomatoes are near that cabbage on a table by accident. "
L52L2
"Listen to part of a lecture in an environmental science class.Professor:Today we are going to begin discussing ecosystems.
One important point I want to emphasize in the reading is that there are many interactions that take place within an ecosystem, interactions between animals, interactions between living and non-living things and so on.
Now these interactions can be fairly simple and straightforward.
Ah, there are certain species of ants and rodents sharing a desert ecosystem in Arizona.
And they compete for the same plants to eat.
And the competition influence is not only the size of the ant and rodent populations, but also the number of eventual plants.
Now, this interaction is easy to see, right?
However, there are many other interactions within ecosystems that are not so apparent and require closer examination.
And the example from your reading was the forest ecosystem along the Pacific coast of North America.
Um, specifically the role of salmon.
Ok, as you probably know, salmon are born in fresh water streams, they might ran to oceans where they spent most of their lives.
And then they return to the same streams where they were born to reproduce, or spawn.
In order to spawn, salmon need cold, clear streams to ensure the survival of their eggs.
And trees in the surrounding forest play an important role here.
Their leaves provide shade from the Sun.
When logging removes the trees, the streams are open to the Sun and the water becomes warmer.
When the water warms up, the concentration of dissolved oxygen in the water decreases.
And this reduces the chance that the salmon eggs will survive.
And the trees also help keep the soil on the banks of the stream in place.
Salmon cannot spawn in streambeds clogged with sediment, dirt, from the surrounding area.
They need a clean, graveled streambed.
Bred?
Bred:I read that salmon also help keep stream healthy.
Professor:Right. Salmon contribute important nutrients like carbon and phosphorus.
And these nutrients promote diversity in the stream environment.
Ok, um, so salmon need trees to successfully reproduce, but surprisingly trees also need salmon.
And bears play an important intermediary role.
So in the autumn, bears are busy putting on extra-weight as they prepare to hibernate.
Each bear catches an estimated 700 fish during the 45 days that the salmon are spawning.
The bears catch the salmon in the streams and then they carry them back into the forest to eat.
Sometimes as much as 800 meters from the streams.
And since the bears only eat about half of each fish they catch, other animals like eagles, crows and insects feed on the leftovers.
Maria?
Maria:Why did the bears bring the salmon so far into the forest?
Why not just eat the fish near the streams?
Professor:Well, imagine several hungry bears looking for salmon.
When one bear catches a fish, it’s not uncommon for another bear to try stealing it.
These confrontations can be pretty intense.
So it’s safer to bring it back into the forest, to a place where the bear can eat undisturbed.
Bred:Um, you said that the bears only eat half of each fish they catch?
I mean if I were a bear preparing to hibernate, I probably eat everything I can catch.
Professor:Well, certain parts of a salmon are more nourishing, fattier than others.
It’s actually more efficient for a bear to only eat some parts of the fish and then try catching another one, instead of eating the whole fish.
Ok. So after the scavengers have eaten the leftovers, only the fish’s skeleton remains.
Now, salmon contain nitrogen.
So their decomposing bodies as skeletons provide a lot of nitrogen to the surrounding forest.
Plants absorb this nitrogen which they need to grow.
So the transfer of this nitrogen to the forest is important.
Forest near streams with salmon actually reach maturity faster than other forests.
Ok, so, why’s all these important?
Well, salmon are in trouble.
Some of their populations have gone extinct. And most of the remaining populations have been significantly reduced by overfishing and environmental challenges.
Now, conservationists can try to prevent overfishing but, well, I mean you can see the interconnections within this ecosystem.
We’ve already talked about the importance of trees to salmon and the negative effect that something like logging can have.
So you can see that protecting this ecosystem is going to take a broad effort. "
L52C2
"Listen to part of a conversation between a student and an employee at the campus store.Student:I'd like the ceramic coffee mugs you have on display at the other end of the store.
Were they made by students?
Employee:Oh, we only use certain suppliers, wholesalers who've been selected by the store manager.
Student:Do you ever sell things made by students?
Employee:We used preferred vendors only because...I mean if we said yes to one student, we'd have to say yes to any student who asks.
And this store is only so big.
Student:That's too bad because I made these pretty ceramic bowls, I designed them myself, I'm a studio art major.
Anyway...um...I was hoping I could sell them here.
You see I'm taking art 202, marketing your art.
And for my final project I need to find a way to sell my own art work.
Employee:Um...what about selling on line?
A lot of art and crafts are marketed that way......
Student:I really don't have the computer skills or the time to manage a website.
Employee:What about the emporium?
You know, that gift shop downtown.
I've seen items by the local artists there.
Student:The emporium buys directly from the artists?
Employee:Well, they sell items on consignment.
Student:Consignment...I think my professor mentioned that.
Employee:Yeah, you give them some items to sell on your behalf and then you and the stores split the purchase price.
But they wouldn't pay you anything up front if that's what you want.
And you might need to provide your own display case.
Student:Oh, I already have a display case, a portable one with three shelves.
But aren't the shops that were...you know, just buy stuff from me outright?
Because if not enough bowls were sold, how would I recoup the cost of my materials?
They are not cheap and neither was the case.
Employee:All the stores around here that sell craft items are small and independently owned, unlike the emporium.
For them, selling on consignment lowers their risk.
They don't get stuck with unsold items.
They can return them to the owner.
You just have to make sure you set the retail price high enough to make it worth you want.
But you're right, consignment isn't for everyone.
What about the spring craft fair?
You know that outdoor market that's held on Saturdays?
Plenty of local people sell their stuff there, ceramics, jewelry, decorative items.
The vendor fee is nominal I believe.
Student:Oh, yeah. I remember seeing that last year.
All those tables lined up in that vacant lot on main street, right?
Employee:Right. Since the craft fair's only a few blocks from campus, it seems like a good place for students to sell things.
Student:Do you know how it works?
Employee:I think you just run to space and set up your table to display your bowls on.
You'd set the prices and keep all the profits.
Student:Seems doable.
But...um... I don't have a car to haul everything down there.
Employee:You could take the campus bus. It goes into town on weekends.
Student:True...um... but I'd also have to sit there all day when I should be in the library or the studio...
I don't know, I suppose I could do my reading assignments between customers. "
L52L3
"Listen to part of a lecture in a chemistry class.Professor: Ok, so, today we’re going to talk about the Arctic, ozone depletion and snowflakes.
And it’s all related.
Let’s start with snowflakes.
Now, I find snowflakes fascinating.
To even begin to understand them, you need to understand physics, chemistry, and mathematics.
Even though there’s been a lot of research, there’re still actually a lot about snowflakes that we don’t understand yet.
Hard to believe, I know.
Anyway, snowflakes have a particular form, there’s a six-sided center with six branches or arms that radiate out from it.
But how did they get that way?
Well, you start with water vapor.
You need a pretty humid atmosphere.
And that water vapor condenses directly into ice, into an ice crystal.
At this point it looks kind of like a thin dinner plate that rather than being circular, is hexagonal with six flat edges.
It’s at this point in the process were we begin to see why each snowflake is unique.
Imagine this dinner plate is floating around in the wind, right?
And when it encounters water vapor, molecules from that vapor attached to each of the six sides.
You begin this development with six arms or branches radiating out from the center plate.
Each time the snowflake encounters water vapor, more molecules attached to it, leading to more and more complex structures.
And of course, each snowflake takes unique route through the clouds on its way down.
And so the quantity of water vapor that it goes through is going to be unique for each one.
Now one important characteristic of snowflakes is that they have something called a quasi-liquid layer, the QLL.
Our snowflake is an ice crystal, right?
Well, we find a quasi-liquid layer on the surface of ice is basically a thin layer of water that’s not completely frozen.
And the existed temperature is well below freezing, though thickness varies at different temperatures.
Now this quasi-liquid layer, it plays an important role on what we are going to talk about next.
Ah, yes, Mary?
Mary:How can liquid exist below freezing?
Why doesn’t it freeze?
Professor:Well, when water becomes ice, the molecules bond together and it gets sort of…locked in the place.
They can’t move around as much anymore.
So each molecule is surrounded by other molecules, and they are all locked together.
But what about the exterior of the ice?
There is a layer of water molecules on the surface, they attached molecules only on one side.
So, they are a bit freer.
They can move around a bit more.
Think of a… think of a brick wall.
The bricks in the wall, they have other bricks above and below them, and they are all locked against each other.
But that top layer, it only has a layer below it.
Now this can only be taken so far because of course bricks don’t move at all.
They are not liquid.
But the bricks of water molecules, well, this top layer would be the quasi-liquid layer.
And it wouldn’t be completely frozen.
Does that make sense?
So, finally we get to the connection between snowflakes and ozone.
Ozone is a gas found in the atmosphere of Earth.
Now there is the ozone found in the stratosphere which is the layer of the atmosphere from 6 to 30 miles above the Earth.
This is considered good ozone, which occurs naturally and helps block harmful radiation from the Sun.
But there is also ground-level ozone.
It’s exactly the same gas but it’s found closer to the surface of the Earth.
This ground-level ozone results from human activities, at high concentrations it can be a pollutant.
Now snowflake’s quasi-liquid layer plays an important role in some complex chemical reactions.
We’re going to be looking at these in detail later today.
But basically, these reactions cause certain chemicals to be released.
And these chemicals reduce the amount of ground-level ozone.
So the more branches you have in an ice crystal, the more quasi-liquid layer there is.
The more quasi-liquid layer, the more reactions and the more chemicals that reduce ground-level ozone.
So you can see why this is such an important system to study and understand. "
L52L4
"Listen to part of a lecture in an archeology class.The professor has been discussing ancient Mayan civilization.
Professor: Now, as you remember from your reading, the Maya were an ancient civilization which occupied in area corresponding to parts of modern-day Mexico and Central America.
Early Mayan settlements date back over 3,000 years and say from about 600 to 900 C.E.
The civilization was in what’s considered a golden age of cultural achievement, what we call the Classic period.
The period after this, after the Classic Period, is called the Postclassic period.
Now it’s long been thought that during the PostClassic period, Mayan civilization was in decline.
But we’re continuing to find new evidence that in certain areas Mayan civilization flourished right up to the end of the Postclassic period, what we refer to as the late Postclassic period.
The late Postclassic corresponds to the period from the 1200s to 1500s, right until the arrival of the Spanish in the mid-1500s.
A good example of a site which continued to flourish through the late Postclassic is the inland Mayan community of Lamanai, located in what is today the country of Belize in Central America.
Now, Lamanai is one of the largest and most prominent archeological sites in Belize.
It was occupied for over 3000 years.
That makes it the longest continually-occupied site by the ancient Maya.
Large-scale excavation at Lamanai began back in 1974 under the leadership of a Canadian archeologist.
The first excavation there was on a building that dated back to the late Postclassic period.
When the excavation began, we didn’t know much about Mayan life during that time.
As I said, most people considered the Postclassic period as a time of decline that came after the so-called golden era.
But during the first few years of excavation, the archeological team realized that Lamanai had continued to be an important center of classic Mayan culture, almost right up until the 1500s.
Student: So basically, what you are saying is while other Mayan cities were collapsing or had already collapsed, Lamanai was one of those places that was flourishing?
Professor: Uh huh…exactly! In fact, the evidence shows that one of the greatest periods of construction in the city occurred during the Postclassic.
That’s definitely not what was happening at neighboring sites during that time.
And consider this, archeologists found ceramic artifacts from Lamanai’s late Postclassic period at a recently-discovered site on an island off the coast of Belize.
And in Lamanai they found objects that had been imported from parts of the region which correspond to modern-day Mexico during the late Postclassic.
What did those finds tell us?
Female student: eh…the trade was still going on?
So you probably still find the same Mayan social structure and economic practices, right?
Professor: Yes. Now, these researchers and subsequent research teams have been helping us see a bigger picture.
We now know that there was still a widespread trading network up and down a long portion of the coast of what is modern-day Mexico and Central America for more than two centuries after the golden era ended. Those finds are telling.
Female student: How big is Lamanai overall?
Professor: Well, in all, 700 stone structures have been documented.
It takes several life times and lots of funding to uncover all of them.
Ok, if that’s not a helpful mental picture…all right here’s another detail that might help.
There was once a population between 35 and 55 thousand there.
The southernmost end of Lamanai had become the city center by the Postclassic period.
It was there at the southern end that people continued to develop technological capabilities, especially in ceramics and eventually in metal work.
The center of Lamanai society had previously been in the northern part of the city.
We’re not yet sure why the focus of life shifted southward only that it did.
Female student: Was the former center, the one in the north smaller than the new one in the south? Like maybe the population grew so they needed more room and moved?
Professor: Actually, the new city center was smaller.
It’s possible that’s because the population had decreased by that point so they actually needed less room.
In any case, the restructured community thrived. "
L53C1
"Listen to a conversation between a student and his drama professor.Hi Robert. So how's your paper going?
Robert: Pretty well. It's a lot of work, but I’m getting into it, so I don't mind.
I’ll probably have some questions for you in the next week or so.
Okay. Glad to hear you’re progressing so well.
Um… There was something you said at the end of the lecture on Tuesday, something about there not really being any original plays.
There’s no such thing as an original play.
Yes. That's the direct quote from Charles Mee.
Mee… that's with two “e”s, right?
Yep. M-E-E. You'll probably be hearing a lot about him.
He's becoming a pretty famous playwright.
Yeah，well, I’ve been thinking about his quote.
I mean there must be some original plays out there.
I’ll grant that he's overstating things somewhat.
But the theater does have a long tradition of borrowing.
Take Shakespeare. Like most writers of his day, he borrowed plots from other sources unabashedly
And the ancient Greeks, all the plays they wrote were based on earlier plays, poems and myths.
And borrowing applies to plays being written nowadays, too?
To some extent, yes.
Mee, for example, he's made a career out of remaking plays, one of which we’ll be studying soon.
It’s called Full Circle and Mee based it on an earlier play by a German playwright.
Oh Full Circle… Wasn't that based on the Caucasian Chalk Circle?
That's right.
I remember hearing about that play from my acting coach.
Okay. Well, the Caucasian Chalk Circle was based on a play by yet another German playwright,someone who was fascinated by the ancient literatures of China, India and Persia,
and many of his works were adapted from those literatures, including his version of the Chalk Circle which was based on an early Chinese play.
So this Full Circle play, by Charles Mee, the one we're going to study, it's like the third or fourth remake.
Wow… And we complain that Hollywood keeps making the same movies over and over again.
Well, part of what Mee’s trying to do is drive home the point that: One, theater’s always a collaborative effort.
Well, yeah, the playwright, the director, the actors, people have to work together to produce a play.
Yes, of course. But Mee means historically.
The dramatic literature of early periods is hugely influential in shaping later dramatic works.
So it's like when the playwright bases a play on a previous playwright's theme or message.
It's like they're talking to each other, collaborating.
Uh, just not at the same time right?
Exactly. And the second point Mee's trying to make, I think, is that it's legitimate to retell an old story in a new way, in a way that’s, uh… more in line with contemporary concerns.
So when playwrights reinvent or update an earlier play, it shouldn't be construed as a lack of imagination or an artistic failure. "
L53L1
"Listen to part of a lecture in a film studies class.Professor: Nowadays we take sound in films for granted.
I mean you still might see black and white films occasionally.
But you'll hardly ever see silent films anymore.
So it's interesting to note that the use of recorded sound was originally controversial.
And some directors, uh, some filmmakers even thought it shouldn't be used, that it would destroy the purity of cinema, somehow reverse all the progress that had been made in the art of cinema. Abby?
Abby: What about all the sounds you hear in some silent movies?
Like, you know, a loud sound when somebody falls down or something?
Professor: Okay, you're talking about a soundtrack added much later, which has over time become part of the film we know.
But this recorded track didn't exist then.
And it's not that most people didn't want sound in films.
It's just that the technology wasn't available yet.
Don't forget that instead of recorded sound, there was often live music that accompanied movies in those days, like a piano player or a larger orchestra in the movie theater.
Also, think of the stage, the live theater, it has used wonderful sound effects for a long time.
And if wanted, these could be produced during the viewing of a film.
You know, the rolling of drums for thunder or whatever.
But that wasn't as common.
Oh, and another thing, that they might have in movie theaters in the early days, was a group of live actors reading the parts to go along with the film,
or, and this seems a particularly bad idea to us now, one person narrating the action, an early example of a long tradition of movie producers,
the ones concerned mostly about making money, not having much confidence in their audience, thinking that people somehow couldn't follow the events otherwise.
So, it finally became possible to play recorded sound as part of the film in the 1920s.
Trouble was, it wasn't always used to very good effect.
First it was, you know, amazing to see somebody's mouth move at the same time you hear the words, or hear a door close when you see it closing on screen.
But that luster wears off, of course. And if you're a director, a filmmaker, what's the next step?
Abby: Well, you sound to enhance the movie right?
Bring something more to it that wasn’t possible?
Professor: Yes. That’s exactly what directors, who were more interested in cinema as art, not commerce, were thinking.
But they also predicted that there would be a problem that sound would be misused and, boy, was it ever.Because the commercial types, the producers and so on, were thinking,
“Okay. Now that sound is possible, let's talk as much as possible and forget about the fact that we're making a movie, that we have this powerful visual medium.”
So many of the films of the twenties were basically straight adaptations of successful shows from the stage, theatre.
The name they used for sound films then was “talking films” and that was on the mark,
since, well, all they pretty much did was talk and talk.
So, remedy?
Well what was proposed by a number of filmmakers and theorists was the creative expressive use of sound,
what they generally called nonsynchronous sound.
Okay, synchronous sound means basically that what we hear is what we see.
Everything on the soundtrack is seen on the screen.
And everything was recorded simultaneously, which… Well, since the sound technicians working on films often had experience with live radio that made sense to them.
Recording the sound separately and adding it in afterward?
Well, that idea was less obvious.
Anyway synchronous sound means the source of the sound is the image on the screen.
Nonsynchronous sound then is…
Abby: The sound doesn't match the picture?
Professor: Right. Now we can look at this in various ways.
But let's take it as literally as possible.
Music, unless we see the radio or the orchestra, that's nonsynchronous.
If the camera shot is of the listener rather than the speaker that's nonsynchronous.
If we hear, say, background sounds that aren't on the screen, that's nonsynchronous.
So, that doesn't seem so radical, does it?
But again, those early producers didn't think their audiences could keep up with this.
Abby: Excuse me, but did you say earlier that some filmmakers actually advocated not using sound at all?
Professor: Well, yes. But that was a bit of an exaggeration, I guess.
What I meant to say was that some filmmakers thought that the way the film sound was actually used was setting the art of filmmaking back.
But everyone agreed that sounds solved some very difficult issues and offered potentially exciting tools. "
L53L2
"Listen to part of a lecture in an environmental science class.Professor: The Chesapeake Bay on the east coast of United States is huge.
The largest estuary in the U.S., and it’s very important to local economies.
But like many of the world’s waterways, the Chesapeake is being polluted.
And efforts to stop that from happening have not been entirely successful.
And that’s partly because of the type of pollution affecting the Chesapeake which may not be what you might predict.
Um, first let’s mention that the sources of pollution are of two general types.
And let’s begin with what’s known as point source pollution.
Point source pollution has an identifiable source
and you can find the specific point where say one particular pipe is dumping pollutants into the bay.
And then treat the water right there where the pollution's coming from.
And that’s what's happened over the past thirty years or so.
Modifications have been made in factories and sewage treatment plants to treat polluted water before it’s released into public waterways.
But there’s also something we call non-point source pollution.
Nowadays the most serious pollution threat doesn’t come from any particular source like a factory or sewage treatment plant,
but originates from many sources over a large area.
And this non-point source pollution is a challenge to deal with
because it doesn’t just enter the bay through one pipe.
You can’t identify precisely where it’s coming from.
And to be specific, the biggest problem now facing the Chesapeake Bay is due not to toxins but to nutrients contained in chemical fertilizers used on farms all over the region.
These nutrients like phosphorus and especially nitrogen wash away what we call agricultural runoff.
That’s when water from a hard rain or from melting snow carries these chemicals down to streams and into the bay.
And there they stimulate the explosive growth of algae
and that uses up much of the oxygen in the water,
oxygen that fish and other aquatic organisms need to stay alive.
So since there is no single place you can treat the runoff before it reaches the bay,
any efforts to reduce this non-point source pollution generally need to be aimed at keeping pollution out of the streams in the first place.
But before we go into that, let’s look at the role of nitrogen fertilizer in modern farming.
Until about sixty years ago, before a great increase in industrialization, this wasn’t a problem.
In the past, farmers use natural fertilizers,and rotated crops so that in addition to commercial food crops like corn and wheat,
they might plant legumes like alfalfa and clover for animal feed.
But these legumes also enriched the soil by converting nitrogen in the atmosphere into nitrates, a form of nitrogen that crops like wheat or corn could use as nutrient.
And these and other cover crops, planted to hold the soil after the wheat or corn was harvested.
They stored much of the surplus nitrogen during the time of the year when the runoff tended to be the greatest.
But farming practices changed as farmers came under pressure to use more and more chemical fertilizer in order to increase crop production on the same amount of land.
But more isn’t always better, at least in terms of chemical fertilizer in the environment.
And along the way, farmers switch from legumes to animal feeds more suited to intensive large scale animal production.
And the excess nitrogen once trapped by these cover crops either washed away in the next big rain or went down into the groundwater and either way eventually ended up in the streams and the bay,
and that as we said means more algae in the water and less oxygen for the fish and other aquatic life to breathe.
So what’s being done? Well, two things.
First, after the main crops are harvested, more farmers are planting cover crops again.
Other kinds like rye and barley that hold the nitrogen and keep it from washing out of the soil during the months when that's most likely to occur.
And the second strategy is to plant buffer zones at the edges of streams.
Not crops but natural areas, trees.
The roots of these trees can absorb the excess nitrogen in the runoff before it reaches the streams.
Farmers sometimes object to letting trees grow on land where they might otherwise be cultivating crops.
But there’s a government program that compensates them,
that pays them for creating these buffer zones between their fields and the streamsthat eventually feed into bays like the Chesapeake and it’s beginning to show some success. "
L53C2
"Listen to a conversation between a student and a cafeteria manager.Oh, hi, you're Amy, right?
Yes.
I haven't seen you here for a while. Welcome back.
Thanks. Uh, you're right. I haven't been eating here regularly like I used to.
Why not?
A couple of reasons.
First of all, I have a class that ends during lunch time.
So by the time I get here, there's hardly any food left.
Really?
Yeah. And then I have a chemistry lab at night this semester.
It's 2 hours every Tuesday and Thursday.
You know that building is way across campus.
So I just eat something in my dorm before I leave or skip dinner altogether.
I come here afterward, but lab lets out at 7:30 and...By then the cafeteria is already closed.
Oh, I'm really sorry. Well, what about getting something to go and eating it in class?
I can’t. Food isn't permitted anywhere near the laboratories. I wish you stayed open later.
Have you complained formally? We've always had a suggestion box. And now, you can send us an e-mail.
As a matter of fact, I did fill out a suggestion card.
I asked for longer hours and for better food choices, too.
But that was like weeks ago. And nothing’s changed from what I can see.
You know, I was just promoted to cafeteria manager, and one of the things I'm trying to do is pay more attention to students' concerns.
There have been a lot of complaints similar to yours over the years.
Yeah. A lot of my friends complain about the cafeteria, but I figure nothing will ever be done.
Well, some things can change.
For instance, you mentioned you like better food choices.
Is there anything in particular you like added to the menu?
Hmm, I guess it'd be nice to get hot cereal in the morning, and maybe a wider choice of soups and salads at lunch and dinner.
And there should definitely be enough food to feed everyone whenever the cafeteria is open.
Hmm hmm. ... But all good suggestions.
Say, were you aware that the university has recently formed a food advisory committee?
It includes myself, a nutritionist, the school chef, a food science professor and the person who oversees the cafeteria budget.
Do you want me to talk to the committee?
I was thinking you might like to serve on the committee. If you are interested, I'll recommend you as the student representative.
Oh, I'm not so sure if I have enough spare time to get that involved.
Ok, then why don't I let you know when and where our next meeting is?
And we will put you on the agenda.
You may also want to send me an e-mail with all of your suggestions.
Now that I am in charge, I will make sure they get serious consideration.
I’d appreciate that, thanks! "
L53L3
"Listen to part of a lecture in a world history class.Professor: Now, according to Chinese legend, the first person to drink tea was a Chinese emperor who lived nearly 5000 years ago. This emperor was, oh, you could call him an amateur scientist.
And he wisely required all drinking water to be boiled for hygiene.
So, once, emm, when visiting some distant part of his empire, he noticed that a breeze had blown some leaves into his pot of boiling water and these leaves turned the water kind of brown.
So, well, would it be your first impulse to drink this?
Probably not. But he thought the resulting brews smell pretty good.
And in the name of science and discovery, he tasted it.
And the practice of drinking tea was born.
Oh, well, a good story.
But actually we cannot say with any certainty just who first discovered how to make tea.
We can be confident though, that the Chinese have been using it in some form for close to 5000 years.
And from those earliest times, more and more tea was cultivated to meet the growing demand, and tea became an important part of the economy of China.
In fact, it was formed into sort of bricks, and used as a common type of currency for trade. But its effect on Chinese culture was even more profound.
Tea became extremely popular in China, and scholars even wrote works discussing how to grow tea, prepare it, drink it, really championing tea; one of them saying it was like the sweetest dew of heaven.
Now, recommendations like this could only add to its huge popularity there.
But tea was also spreading throughout Asia.
In Japan, perhaps even more than in China, tea became a major cultural symbol, and one of refinement of etiquette and aesthetics.
Well, best seen in the traditional Japanese tea ceremony, which is still performed today.
This is an intricate formal ritual, emm, ceremony that can take hours to complete.
Clearly, tea became not just a beverage in Japanese culture but much much more. Tea eventually got to western Europe, after European traders, mainly Portuguese and Dutch, brought the first small commercial shipment of tea back to Europe. Unfortunately, it was mostly just treated as a curiosity, since no one knew quite how it was supposed to be used.
A few has some pretty strong opinions though.
One German doctor wrote a book saying tea was harmful, actually poisonous. But at about the same time, another doctor from Holland wrote another book calling tea ‘a miracle cure for just about everything’. Who to believe?
So, anyway, tea didn’t really catch on in Germany or France, as something just to enjoy drinking, they seem to prefer coffee.
But England did take to tea.
And to an extent that nobody could have foreseen.
Such that, even today we tend to associate England, Great Britain with tea.
And, well, a bit of perspective, at the start of the 18th century, almost nobody in England drank tea.
But by the end of it, almost everybody did.
By the 1750s, official records show tea imports up from almost nothing to about 20 million kilos.
And those records didn’t even begin to account for all the tea smuggled into the country illegally to avoid paying taxes. And as for reasons for the popularity of tea there, well, tea first became fashionable after the king of England married a Portuguese princess who loved tea.
And pretty soon, more and more people started copying her and drinking tea. Later, when a direct trade route was established between China and England, the supply of tea greatly increased.
Most important though, tea drinking became sociable.
And although coffee houses or tavern were generally considered to be for men only, tea shops became places where women could come.
And even bring their families.
And soon there were tea parties, books on tea etiquette, and even tea gardens—parks filled with lights and walkways and venues for musical performances, places where people of all social classes could go to drink tea and socialize.
By the end of the 18th century, all classes of English society drank tea, from royalty to common workers.
Tea became a staple of everyday life, part of the common culture, and traditionally considered by many, the very mark of being English. "
L53L4
"Listen to part of a lecture in an astronomy class.Professor: Saturn’s rings have always baffled astronomers.
Until about 30 years ago, we thought the rings were composed of particles of ice and rock that were left over from Saturn’s formation, extra material that never managed to form er...er coalesce into a moon.
As you know, it’s believed that Saturn and all the planets in our solar system, coalesced from a swirling cloud of gas some 4.8 billion years ago.
However, if the rings are made of leftovers from that process, then they’d also be about 4.8 billion years old.
The problem is that anything gathering space dust for that long would certainly have darkened by now.
But Saturn’s rings, most of them anyway, are pristine, so bright and shiny that they make Saturn “the jewel of the solar system”.
So the hypothesis that the rings are just made of material left over from the time of planetary formation.
That hypothesis must be wrong.
Saturn’s rings are much younger than the planet itself.
They may have formed only a few hundred million years ago, around the time the earliest dinosaurs lived on earth.
We realize now that the ring particles, which range in size from microscopic dust to boulders, bigger than large houses, well, a lot of these particles are eventually lost.
Then we believed they gradually spiral down out of the rings and into the planet’s atmosphere.
This occurs as a result of the planet’s gravity.
And also because of the effects of its magnetic field.
Now, if material from Saturn’s rings is being lost, and nothing new is added from time to time, the rings would be disappearing, but that’s not happening.
So somehow, there must be new material feeding the ring system.
Question is, where is this new material coming from?
So, we’re back to square one.
But, instead of asking how did the rings form, we should be asking… anyone? Beth?
Student: How do the rings form?
Professor: How do the rings form!
Because they are apparently replenishing themselves somehow.
OK, here is one possibility.
The moons, the dozens of moons, they all orbit Saturn, are providing raw material for the rings.
A moon in the system is complex at Saturn’s, and Saturn has at least 49 known moons which vary tremendously in size and shape.
A moon in such a complex system, is not only affected by the gravitational force of the planet, but also by that of the other moons.
Student: So the planet may be pulling a moon one way, and other moons may be pulling it other ways?
Professor: Exactly. Such forces could actually alter a moon's orbit, and as a result there might be a collision when moon might crash into another.
And the debris from that collision could become part of the rings.
Then there are tidal forces, a moon might get too close to the planet and get broken apart by Saturn's tidal forces.
Student: Excuse me! You mean, tidal force is like high tide and low tide on the oceans?
Professor: Well, by tidal force, I'm referring to the gravitational pull of Saturn on its moons.
In the mid-1800s, a French scientist named Edouard Roche was studying the effects of a planet's tidal forces on its moons.
Roche was able to show mathematically that if one celestial body, say a moon, if it passes too close to another, say a planet, that has a gravitational force stronger than the force of self-attraction that holds the moon together.
Well, that first body，that moon， it'd be ripped apart.
We call the distance at which this happens the ""Roche limit"".
So if one of Saturn's moons reaches the Roche limit of the planet, or even a larger moon, it would disintegrate, be torn apart and thus add more material to the ring system.
And there's another way new material might be added to the Saturn's rings, an asteroid crashing into one of the moons.
This hypothesis is supported by the fact that some of the many rings are a bit reddish in color. Yes, George?
Student: I'm sorry, I don't follow the logic.
Professor: Well, this reddish coloration suggests the presence of complex organic molecules, carbon-based molecules, mixed in with the water ice.
Remember, the rest of Saturn's rings are made almost entirely of water ice.
And none of Saturn's moons is red.
But asteroids could be.
And thus could end up contributing to the ring system, the kind of carbon-based molecules we're talking about. "
L54C1
"Listen to a conversation between a student and a professor of her theater class.Student:So, Professor Baker, about our next assignment you talked about in class.
Professor:Yes, this time you'll be in groups of three, each of you will have a chance to direct the other two in a short scene from a play you've chosen yourself.
Student:Right, and, well, I've been reading about story theater, and
Professor:Ah, story theater, tell me about what you've read.
Student:Well, it's a form of theater where folk or fairy tales are acted out.
It was…eh, introduced, by the director Paul Sills in the 1960s.
In Sills's approach, an actor both narrates, and acts out a tale.
So, like someone will appear on stage, and then will start narrating a tale, about…say a king, and then the same person will immediately switch to and start acting out the role of the king, with no props or scenery.
Professor:Sills, you know I actually saw his first story theater production in 1968, he did the fairy tale ‘the blue light
Student:Really, so whatever gave him the idea to produce that?
Professor:Well, as you know, back in the late 1960s, lots of people in the United States were disillusioned with the government.
Sills was grappling with how to produce theater that was relevant in such times.
Then he happened to read ‘the blue light', and he realized that it had just the message he wanted.
See, in the story, a man has lost all hope as a result of the unfortunate events in his life, completely turns his life around, with the help of a magical blue light.
So,the blue light in the story symbolizes a way out of seemingly unsolvable human problems.
And for Sills, that light symbolized an answer to the political turmoil in the US.
Student:But weren't you…um, audiences bother that the actors were performing on a bare stage?
Professor:Well, story theater is a departure from traditional dramatic theater with its realistic elaborate props and scenery, but Sills could make us see, say a big tall mountain through the facial expressions and body movements of the actors, and they're telling of the story.
We were all swept up, energized by such an innovative approach to theater, even if one or two of the critics weren't as enthusiastic.
Student:Cool, so, anyway.
What I really wanted to ask, I'd love to try doing story theater for my project instead of just a scene from a traditional play.
Professor:Um, that's possible.
A short tale can be about the same length as a single scence.
Which fairy tale would you do?
Student:Actually, I was reading about another director of story theater, Rack Stevenson.
You know, he produces plays based on folk tales as well.
Maybe I could direct one of those.
Professor:Okay, yes, Rack Stevenson.Now, Stevenson's style's story theater is a little different from Sills's.
He'll use simple props, a chair will represent a mountain, but the significant difference is with the narrator.
The narrator will play only that role.
Let's talk about why. "
L54L1
"Listen to part of the lecture in the marine biology class.And the sea is teaming with tiny organisms, but they don't get as much popular attention as say, whales.
Microscopic algae just aren't as exciting I suppose.
And yet those organisms are the foundation of the bulk of the marine food chain.
Without plankton which is the global term for these tiny organisms, there will be no whales.
Plankton is found both in fresh water and marine environments.
Again it's a term we use for any small organisms that float along with the current, either because they are too small or weak to swim against it, or because they don't have any capacity at all to move by themselves.
Plants and plant-like plankton are called phytoplankton while animals and animal-like plankton are called zooplankton.
For over a century now, researchers have been trying to solve the mystery about zooplankton.
You see some species of zooplankton migrate are……um…… not the way birds do when the seasons change.
But daily, in the phenomenon we call Diel Vertical Migration or DVM, in the Diel Vertical Migration, sole plankton swim up near the surface of the water during the night and swim down to deeper water during the day.
Depending on the species and region, this can be a round trip of between 100 and 400 meters.
For a tiny microscopic organism, that's a huge distance.
Remember now, zooplankton can't swim very well and DVM requires a lot of energy.
So there must be an important benefit to these daily up-and-down commuting.
We're not exactly sure what this benefit is.
Though there are several compelling theories.
I'll talk about them in a moment, but first I want to talk about what we do know or rather what we are pretty sure we know.
So researchers generally agree that the stimulus for zooplankton DVM is light.
Zooplankton tend to swim away from sunlight into deeper water where the sun's rays barely penetrate.
At night, when the sun no longer illuminates shallower water, zooplankton head back toward the surface.
Now why would light cause zooplankton to expend all that energy in migrate?
One popular theory is that zooplankton are hiding during the day from visual predators, eh……those animals that hunt by sight, the darkness provides safety during the day.
Then at night after migrating upward, they have an opportunity to feed on phytoplankton that float at the surface.
Make sense, doesn't it?
But what do we do with the data showing that many kinds of zooplankton don't dive deep enough during the day to become invisible to predators or that others dive deeper than it's necessary to escape hunters' eyes.
And some zooplankton are bioluminescent, which means they have special organs that light up and make them visible even at great depth.
Well, despite all these, we believe predator avoidance is a possible explanation because of studies done in fresh water lakes.
It turns out there is a correlation between the presence or absence of vertical migration, and the presence or absence of fish that find their prey by sight.
But what are some other possible explanations?
Some researchers suggest that zooplankton migrate to avoid the sun's ultra-violet light.
That would explain why some zooplankton are found at such great depth.
Visible light may not penetrate very far down, but ultra-violet light can.
And we know that some zooplankton have special pigments that protect them from the damage ultra-violet light can cause.
That could be why some zooplankton are able to stay closer to the surface during daylight hours.
And there is a third theory.
Although it takes a lot of energy for the zooplankton to migrate, they conserve energy while floating in deeper colder water.
So while they're not feeding, they are quietly digesting in cooler water.
But remember, zooplankton consist of any number of different organisms.
From microscopic worms to crab larvae to tiny fish, and they are found in a large range of marine habitats, cold water, warm water, shallow water, deep water.
So there may be different reasons for different species. "
L54L2
"Listen to part of a lecture in an archaeology class.Professor: A popular misconception about archaeology, some people imagine we just go out into the field with a shovel and start digging, hoping to find something significant.
Well, while there is an element of luck involved, we have an array of high-tech tools to help us figure out where to concentrate our efforts.
One of the newer tools actually relies on particle physics, talk about inter-disciplinary.
Here is a machine that brings together two very different sciences.
This machine is called a muon detector.
Muons are subatomic particles that result from cosmic rays.
OK, let me start over.
Cosmic rays aren't actually rays.
They are basically protons zipping through outer space at close to light speed.
And, when they collide with the atoms in earth's atmosphere, they break up into smaller particles -- muons.
Now these muons are still highly energized, so they can easily pass on down to the earth's surface.
In fact, they can pass through solid matter, so they can also penetrate deep into the surface.
And it's this property of muons that archaeologists are taking advantage of.
Let me explain, with the right kind of equipment, scientists can use muons to create a kind of picture of the structures they are studying.
Let's say we are studying a Mayan pyramid in central America.
And we are interested in finding out if there are burial chambers or other rooms inside.
Well, a muon detector will show a greater number of muons passing through the less dense areas inside the pyramid.
Yes, Andrew?
Um…I'm not sure I get how this muon detector works exactly.
Well, muons lose energy as they pass through dense material, like the stone walls of the Mayan pyramid.
So more muons and more energetic muons will be passing through empty spaces.
The muon detector can differentiate the areas where more muons are passing through -- the empty spaces, as well as where there are fewer muons, the walls and dense areas.
These empty spaces will show up as darker, so we wind up with a kind of picture of the pyramid, and its internal structure.
A picture?
Sort of like an X-ray image.
Ok, so if we see darker areas inside the pyramid, we assume it's an empty space with more muons.
Exactly, with this technology, we can see what's inside the structure before we dig, so we know exactly where to explore and we can minimize the damage excavation can cause.
Even a little damage could result in us losing vital information forever.
Now, muon detectors have been around for some time, but they have been improved upon since archaeologists started using them.
In 1967 a physicist placed a muon detector beneath the base of one of the Egyptian pyramids of Giza.
And he was looking for burial chambers.
Now it happened that the muon detector found none.
But he did demonstrate that the technique worked.
Unfortunately the machine he used was so big that many archaeologists doubted muon detection could be practical.
How could they get a massive piece of equipment into, say, the jungle of Belize?
Then there was the issue of range.
The machine used in 1967 could only scan for muons directly above it, not from the sides.
So it actually had to be put underneath the pyramid, so it could look up.
That meant if you wanted to find out what was inside an ancient structure, you first had to bury the detector beneath it.
There's been a lot of work on these machines since then.
And these problems have been solved by and large.
That's not to say the technology is perfect, it would be nice for example, to have a system that didn't take 6 months to produce an image.
I suppose that's better than the year it took for the 1967 study to get results.
But still...well, there is good reason to believe that with better equipment, we're going to see muon detectors used much more frequently.
They are already being used in other areas of science, for example Japanese scientists studying the interior of volcanoes, and there are plenty of archaeologists who would love to use this technology. "
L54C2
"Listen to a conversation between a student and an employee in the university's historical library.Morning, what can I help you find?
Well, I saw the internet that the university library has menus and things from local restaurants, like the Springfield Eatery?
Right, a lot of local businesses have donated materials to our collection, including that restaurant. I'm pretty sure we have ten or fifteen boxes of materials from there.
Good, I thought you were located in the main library, so I went there first and they sent me here. I haven't realized the university has a separate historical library. I think what you're doing is great，collecting local documents and photos, keeping a record of the region.
I'm glad you see the value of it. We've been collecting materials for going on seventy years now. Last year we had an exhibition that showcase how the town square has changed over the past fifty years.So, that got the word out a little, but you're right. A lot of students don't know we exist. Well, unless the major of new history. So, you're looking for something for class?
Not exactly. My grandmother went to this university, and while she was here, she worked as a waitress.
At the Springfield Eatery？
Yes, and that's where she met my grandfather. So, they're celebrating their fiftieth anniversary this year. And I noticed online that you have old menus from some of the restaurants. I was thinking I could find one from the year they met and print a copy for them.
What a unique idea! What year you are looking for?
Um, 1954.
I know we have a few menus from the 1950s, but you'll have to check. There are some gaps, some years we didn't receive any new materials, and sometimes restaurants go a while without changing their menus.
Oh no, I really want to give them something special.
Well, how about this? We also have a lot of photos, so maybe you could find one of your grandmother, or maybe even one with both your grandparents.
That would be awesome.
The only thing is most of our materials are still in boxes. No one's ever taken the time to organize them. So, it …it might require a fair amount of sifting.
Um, I have a couple of tests coming up, but I can take a quick look, if that's okay. I know some libraries have special rules for handling delicate or old materials.
Well, these aren't particularly old. Just the usual rules apply, no food or drinks.
Okay, thanks for your help. "
L54L3
"Listen to part of a lecture in a theater history class.One of the things New York city is known for is its Broadway theaters，the productions of elaborate musicals.
A lot of money goes into producing a musical with the actors, costumes, scenery and so on.
The shows are designed to appeal to large audiences, to make the production financially viable.
But theater didn’t always appeal to the masses.
In the middle of the 19th century, with mostly wealthy residents who were going to Broadway, they would see an opera that was probably written and produced in Europe before making its way all over to New York.
It was a scene for, well, the socially prominent, the upper class, who attended these functions, perhaps, because they felt obligated rather than because of a genuine interest in theater.
But, in the 1860s, something else started to occur.
The middle-class population began to grow, and they were looking for a source of entertainment.
Keep that in mind while I talk about the theater owner named William Wigley.
In 1866, Willian Wigley had this show, um, and it was different from most shows on Broadway at the time because it wasn’t an opera.
And, it was developed right here in the United States, in English, unlike the operas which were typically Italian or French.
Wigley also decided to incorporate some fancy production techniques, stage effects.
The show also included music to make it more entertaining.
And, through a stroke of luck, a world-renown ballet troop became available just as wigley show was about to open.
So, he didn’t hesitate to include the ballet dancers in his production.
Along the lines of those special effects I mentioned, Wigley redesign the entire stage for the show.
Every floor board on the stage could be lifted up or pushed down.
They were all moveable.
This allowed for trap doors to be placed anywhere on the stage.
So, pieces of the set, of the scenery, could easily be stored beneath the stage.
And these trap doors also gave performers another less traditional way to enter in exit of the stage.
Well, today, we might not think much of it, things like this are standard nowadays，the concept was quite novel at the time of Wigley show.
And was one of the things that made the show a hit with audiences.
Another innovative element in the show was a scene called the ‘transformation scene’, during this scene, the audience watched in amazement that a setting on stage changed from a moonlit cave to a throne room in a palace.
Normally to have this type of major scene changed, the curtains were closed, the stage crew would remove the previous set and replaced it with the new one, and then, the curtains would open again.
In this instance though, the transformation to place in front of the audience using simple machinery.
And this affect would have the lasting impression on everyone who saw Wigley’s production.
In fact, those people were probably disappointed when they saw another show that didn’t contain something is, well, as elaborate or exciting.
So, look, when it premiered, Wigley show took audiences by surprise, it appealed to large crowds including the growing middle-class, the show ran for almost two years straight in New York city, and achievement unheard of at the time when productions typically lasted weeks or months, not years.
It also went on tour visiting different cities across the United States for over 25 years.
So, the show was quite a success.
And with all that in mind, some people call Wigley show the first musical on Broadway.
Now our current definition of a musical is that it tells a story through dialogue and song.
In Wigley show the musical sections, well, they didn’t necessarily integrate well with the story.
Giving an overall impression of something more like a variety show, yes, everything was loosely focused around the central scene, so maybe it’s fair to say then that the show gave audiences a hint of a new form of musical theater， that would ultimately appear on Broadway in the decades to follow. "
L54L4
"Listen to part of a lecture in a geology class.About 30 years ago, a geologist named Edward Cotter, that's C-O-T-T-E-R, published a paper that contained a very interesting hypothesis.
He was studying ancient rivers in the North American mountain chain.
And he noticed that about 450 million years ago, rivers started to behave differently.
Before then, rivers were wide, shallow and straight.
But after that time, they became deeper and had more curves.
They became increasingly meandering, and that's actually how rivers behaved till this day.
So why might this change have happened?
Maybe there was some kind of a climate shift?
Well,lots of climate shifts have happened since then.
Was the change worldwide?
Or just in that geographical area?
Well Cotter speculated that rivers changed worldwide, but he couldn't prove it.
Because he only had evidence from the one North American mountain chain.
But his studies gave him an idea about why rivers started to change.
He hypothesized it had to do with the spread of plant life on earth.
So there was no plant life before 450 million years ago?
Very little according to fossil records.
Anyway, geologists were intrigued by this hypothesis which claims that as plants evolved and spread, they had an effect on terrain and rivers.
In the past 30 years, more studies have been done.
And now we have a lot of data about river systems from around 450 million years ago from all over the world.
In a recent study, a couple of researchers gathered together the existing data and combine them with their own new field data to get a comprehensive picture of the situation.
Their study was specifically designed to identify changes in the shapes of rivers during the time period when vegetation was evolving.
And when the researchers compared the data about river shapes with data they have collected about plant life from the same period, the data seemed to prove Cotter's hypothesis.
OK, but how did plant life affect rivers?
Well, in order to answer that question, we need to look at the geological evidence.
You see, as rivers flow, they leave layers of sediment behind that eventually fossilized.
The content, thickness and shape of these fossilized layers and rocks gave us information about how rivers flowed.
The earliest records from 500 million years ago show that the sediment in river deposits was largely composed of quartz grain of sand and gravel.
That tells us that rivers weren't defined, they were very shallow and wide, almost like floods.
But around the time of the rise of plant life, the content of those sediment layers began to change.
The quartz grains became much finer.
And we see evidence of mud.
This suggests that plants promoted the preservation of mud when they sent their roots into the ground.
The roots helped to reinforce the ground, which in turn allowed for the creation of river banks.
And we also see evidence of a process called lateral accretion.
Lateral accretion happens when water flows around the curve or bend in the riverbed.
Now the speed of the flow on the outside of the bend is fastest, and slowest on the inside of the bend.
This sets up what's called the secondary flow across the river bottom.
The fast flowing water on the outside of the bend digs out material from the riverbank and pushes these material laterally across the bottom, and it gets deposited on the other side of the river,on the inner side of the bend.
So, when we see in the sediment layers, evidence of lateral accretion, the erosion on one side and deposits on the other, that's an indicator that meandering rivers existed.
And according to the study, strong evidence of lateral accretion appears in the geological record.
At the same time, there is also evidence of plants with underground root systems.
This suggests that plants promoted the development of modern rivers by creating stable banks, which resulted in the flow of water in single meandering channels.
So it looks like the researchers were able to prove that hypothesis.
Well, there is no denying that this study presents a very strong case.
But some questions about this hypothesis remain.
For example, it's well-known that on other planets, like Mars, there is clear evidence of meandering rivers.
But is there evidence of vegetation on Mars?
I think not. "
R1P1
GroundwaterGroundwater is the word used to describe water that saturates the ground, filling all the available spaces. By far the most abundant type of groundwater is meteoric water; this is the groundwater that circulates as part of the water cycle. Ordinary meteoric water is water that has soaked into the ground from the surface, from precipitation (rain and snow) and from lakes and streams. There it remains, sometimes for long periods, before emerging at the surface again. At first thought it seems incredible that there can be enough space in the "solid" ground underfoot to hold all this water.
The necessary space is there, however, in many forms. The commonest spaces are those among the particles—sand grains and tiny pebbles—of loose, unconsolidated sand and gravel. Beds of this material, out of sight beneath the soil, are common. They are found wherever fast rivers carrying loads of coarse sediment once flowed. For example, as the great ice sheets that covered North America during the last ice age steadily melted away, huge volumes of water flowed from them. The water was always laden with pebbles, gravel, and sand, known as glacial outwash, that was deposited as the flow slowed down.
The same thing happens to this day, though on a smaller scale, wherever a sediment-laden river or stream emerges from a mountain valley onto relatively flat land, dropping its load as the current slows: the water usually spreads out fanwise, depositing the sediment in the form of a smooth, fan-shaped slope. Sediments are also dropped where a river slows on entering a lake or the sea, the deposited sediments are on a lake floor or the seafloor at first, but will be located inland at some future date, when the sea level falls or the land rises; such beds are sometimes thousands of meters thick.
In lowland country almost any spot on the ground may overlie what was once the bed of a river that has since become buried by soil; if they are now below the water’s upper surface (the water table), the gravels and sands of the former riverbed, and its sandbars, will be saturated with groundwater.
So much for unconsolidated sediments. Consolidated (or cemented) sediments, too, contain millions of minute water-holding pores. This is because the gaps among the original grains are often not totally plugged with cementing chemicals; also, parts of the original grains may become dissolved by percolating groundwater, either while consolidation is taking place or at any time afterwards. The result is that sandstone, for example, can be as porous as the loose sand from which it was formed.
Thus a proportion of the total volume of any sediment, loose or cemented, consists of empty space. Most crystalline rocks are much more solid; a common exception is basalt, a form of solidified volcanic lava, which is sometimes full of tiny bubbles that make it very porous.
The proportion of empty space in a rock is known as its porosity. But note that porosity is not the same as permeability, which measures the ease with which water can flow through a material; this depends on the sizes of the individual cavities and the crevices linking them.
Much of the water in a sample of water-saturated sediment or rock will drain from it if the sample is put in a suitable dry place. But some will remain, clinging to all solid surfaces. It is held there by the force of surface tension without which water would drain instantly from any wet surface, leaving it totally dry. The total volume of water in the saturated sample must therefore be thought of as consisting of water that can, and water that cannot, drain away.
The relative amount of these two kinds of water varies greatly from one kind of rock or sediment to another, even though their porosities may be the same. What happens depends on pore size. If the pores are large, the water in them will exist as drops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.
R1P2
The Origins of TheaterIn seeking to describe the origins of theater, one must rely primarily on speculation, since there is little concrete evidence on which to draw. The most widely accepted theory, championed by anthropologists in the late nineteenth and early twentieth centuries, envisions theater as emerging out of myth and ritual. The process perceived by these anthropologists may be summarized briefly. During the early stages of its development, a society becomes aware of forces that appear to influence or control its food supply and well-being. Having little understanding of natural causes, it attributes both desirable and undesirable occurrences to supernatural or magical forces, and it searches for means to win the favor of these forces. Perceiving an apparent connection between certain actions performed by the group and the result it desires, the group repeats, refines and formalizes those actions into fixed ceremonies, or rituals.
Stories (myths) may then grow up around a ritual. Frequently the myths include representatives of those supernatural forces that the rites celebrate or hope to influence. Performers may wear costumes and masks to represent the mythical characters or supernatural forces in the rituals or in accompanying celebrations. As a person becomes more sophisticated, its conceptions of supernatural forces and causal relationships may change. As a result, it may abandon or modify some rites. But the myths that have grown up around the rites may continue as part of the group’s oral tradition and may even come to be acted out under conditions divorced from these rites. When this occurs, the first step has been taken toward theater as an autonomous activity, and thereafter entertainment and aesthetic values may gradually replace the former mystical and socially efficacious concerns.
Although origin in ritual has long been the most popular, it is by no means the only theory about how the theater came into being. Storytelling has been proposed as one alternative. Under this theory, relating and listening to stories are seen as fundamental human pleasures. Thus, the recalling of an event (a hunt, battle, or other feat) is elaborated through the narrator’s pantomime and impersonation and eventually through each role being assumed by a different person.
A closely related theory sees theater as evolving out of dances that are primarily pantomimic, rhythmical or gymnastic, or from imitations of animal noises and sounds. Admiration for the performer’s skill, virtuosity, and grace are seen as motivation for elaborating the activities into fully realized theatrical performances.
In addition to exploring the possible antecedents of theater, scholars have also theorized about the motives that led people to develop theater. Why did theater develop, and why was it valued after it ceased to fulfill the function of ritual? Most answers fall back on the theories about the human mind and basic human needs. One, set forth by Aristotle in the fourth century B.C., sees humans as naturally imitative—as taking pleasure in imitating persons, things, and actions and in seeing such imitations. Another, advanced in the twentieth century, suggests that humans have a gift for fantasy, through which they seek to reshape reality into more satisfying forms than those encountered in daily life. Thus, fantasy or fiction (of which drama is one form) permits people to objectify their anxieties and fears, confront them, and fulfill their hopes in fiction if not fact. The theater, then, is one tool whereby people define and understand their world or escape from unpleasant realities.
But neither the human imitative instinct nor a penchant for fantasy by itself leads to an autonomous theater. Therefore, additional explanations are needed. One necessary condition seems to be a somewhat detached view of human problems. For example, one sign of this condition is the appearance of the comic vision, since comedy requires sufficient detachment to view some deviations from social norms as ridiculous rather than as serious threats to the welfare of the entire group. Another condition that contributes to the development of autonomous theater is the emergence of the aesthetic sense. For example, some early societies ceased to consider certain rites essential to their well-being and abandoned them, nevertheless, they retained as parts of their oral tradition the myths that had grown up around the rites and admired them for their artistic qualities rather than for their religious usefulness.
R1P3
Timberline Vegetation on MountainsThe transition from forest to treeless tundra on a mountain slope is often a dramatic one. Within a vertical distance of just a few tens of meters, trees disappear as a life-form and are replaced by low shrubs, herbs, and grasses. This rapid zone of transition is called the upper timberline or tree line. In many semiarid areas there is also a lower timberline where the forest passes into steppe or desert at its lower edge, usually because of a lack of moisture.
The upper timberline, like the snow line, is highest in the tropics and lowest in the Polar Regions. It ranges from sea level in the Polar Regions to 4,500 meters in the dry subtropics and 3,500-4,500 meters in the moist tropics. Timberline trees are normally evergreens, suggesting that these have some advantage over deciduous trees (those that lose their leaves) in the extreme environments of the upper timberline. There are some areas, however, where broadleaf deciduous trees form the timberline. Species of birch, for example, may occur at the timberline in parts of the Himalayas.
At the upper timberline the trees begin to become twisted and deformed. This is particularly true for trees in the middle and upper latitudes, which tend to attain greater heights on ridges, whereas in the tropics the trees reach their greater heights in the valleys. This is because middle- and upper- latitude timberlines are strongly influenced by the duration and depth of the snow cover. As the snow is deeper and lasts longer in the valleys, trees tend to attain greater heights on the ridges, even though they are more exposed to high-velocity winds and poor, thin soils there. In the tropics, the valleys appear to be more favorable because they are less prone to dry out, they have less frost, and they have deeper soils.
There is still no universally agreed-on explanation for why there should be such a dramatic cessation of tree growth at the upper timberline. Various environmental factors may play a role. Too much snow, for example, can smother trees, and avalanches and snow creep can damage or destroy them. Late-lying snow reduces the effective growing season to the point where seedlings cannot establish themselves. Wind velocity also increases with altitude and may cause serious stress for trees, as is made evident by the deformed shapes at high altitudes. Some scientists have proposed that the presence of increasing levels of ultraviolet light with elevation may play a role, while browsing and grazing animals like the ibex may be another contributing factor. Probably the most important environmental factor is temperature, for if the growing season is too short and temperatures are too low, tree shoots and buds cannot mature sufficiently to survive the winter months.
Above the tree line there is a zone that is generally called alpine tundra. Immediately adjacent to the timberline, the tundra consists of a fairly complete cover of low-lying shrubs, herbs, and grasses, while higher up the number and diversity of species decrease until there is much bare ground with occasional mosses and lichens and some prostrate cushion plants. Some plants can even survive in favorable microhabitats above the snow line. The highest plants in the world occur at around 6,100 meters on Makalu in the Himalayas. At this great height, rocks, warmed by the sun, melt small snowdrifts.
The most striking characteristic of the plants of the alpine zone is their low growth form. This enables them to avoid the worst rigors of high winds and permits them to make use of the higher temperatures immediately adjacent to the ground surface. In an area where low temperatures are limiting to life, the importance of the additional heat near the surface is crucial. The low growth form can also permit the plants to take advantage of the insulation provided by a winter snow cover. In the equatorial mountains the low growth form is less prevalent.
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Desert FormationThe deserts, which already occupy approximately a fourth of the Earth's land surface, have in recent decades been increasing at an alarming pace. The expansion of desertlike conditions into areas where they did not previously exist is called desertification. It has been estimated that an additional one-fourth of the Earth's land surface is threatened by this process.
Desertification is accomplished primarily through the loss of stabilizing natural vegetation and the subsequent accelerated erosion of the soil by wind and water. In some cases the loose soil is blown completely away, leaving a stony surface. In other cases, the finer particles may be removed, while the sand-sized particles are accumulated to form mobile hills or ridges of sand.
Even in the areas that retain a soil cover, the reduction of vegetation typically results in the loss of the soil's ability to absorb substantial quantities of water. The impact of raindrops on the loose soil tends to transfer fine clay particles into the tiniest soil spaces, sealing them and producing a surface that allows very little water penetration. Water absorption is greatly reduced; consequently runoff is increased, resulting in accelerated erosion rates. The gradual drying of the soil caused by its diminished ability to absorb water results in the further loss of vegetation, so that a cycle of progressive surface deterioration is established.
In some regions, the increase in desert areas is occurring largely as the result of a trend toward drier climatic conditions. Continued gradual global warming has produced an increase in aridity for some areas over the past few thousand years. The process may be accelerated in subsequent decades if global warming resulting from air pollution seriously increases.
There is little doubt, however, that desertification in most areas results primarily from human activities rather than natural processes. The semiarid lands bordering the deserts exist in a delicate ecological balance and are limited in their potential to adjust to increased environmental pressures. Expanding populations are subjecting the land to increasing pressures to provide them with food and fuel. In wet periods, the land may be able to respond to these stresses. During the dry periods that are common phenomena along the desert margins, though, the pressure on the land is often far in excess of its diminished capacity, and desertification results.
Four specific activities have been identified as major contributors to the desertification processes: overcultivation, overgrazing, firewood gathering, and overirrigation. The cultivation of crops has expanded into progressively drier regions as population densities have grown. These regions are especially likely to have periods of severe dryness, so that crop failures are common. Since the raising of most crops necessitates the prior removal of the natural vegetation, crop failures leave extensive tracts of land devoid of a plant cover and susceptible to wind and water erosion.
The raising of livestock is a major economic activity in semiarid lands, where grasses are generally the dominant type of natural vegetation. The consequences of an excessive number of livestock grazing in an area are the reduction of the vegetation cover and the trampling and pulverization of the soil. This is usually followed by the drying of the soil and accelerated erosion.
Firewood is the chief fuel used for cooking and heating in many countries. The increased pressures of expanding populations have led to the removal of woody plants so that many cities and towns are surrounded by large areas completely lacking in trees and shrubs. The increasing use of dried animal waste as a substitute fuel has also hurt the soil because this valuable soil conditioner and source of plant nutrients is no longer being returned to the land.
The final major human cause of desertification is soil salinization resulting from overirrigation. Excess water from irrigation sinks down into the water table. If no drainage system exists, the water table rises, bringing dissolved salts to the surface. The water evaporates and the salts are left behind, creating a white crustal layer that prevents air and water from reaching the underlying soil.
The extreme seriousness of desertification results from the vast areas of land and the tremendous numbers of people affected, as well as from the great difficulty of reversing or even slowing the process. Once the soil has been removed by erosion, only the passage of centuries or millennia will enable new soil to form. In areas where considerable soil still remains, though, a rigorously enforced program of land protection and cover-crop planting may make it possible to reverse the present deterioration of the surface.
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The Origins of CetaceansIt should be obvious that cetaceans-whales, porpoises, and dolphins-are mammals. They breathe through lungs, not through gills, and give birth to live young. Their streamlined bodies, the absence of hind legs, and the presence of a fluke1 and blowhole2 cannot disguise their affinities with land dwelling mammals.However, unlike the cases of sea otters and pinnipeds (seals, sea lions, and walruses, whose limbs are functional both on land and at sea), it is not easy to envision what the first whales looked like. Extinct but already fully marine cetaceans are known from the fossil record. How was the gap between a walking mammal and a swimming whale bridged? Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans.
Very exciting discoveries have finally allowed scientists to reconstruct the most likely origins of cetaceans. In 1979, a team looking for fossils in northern Pakistan found what proved to be the oldest fossil whale. The fossil was officially named Pakicetus in honor of the country where the discovery was made. Pakicetus was found embedded in rocks formed from river deposits that were 52 million years old. The river that formed these deposits was actually not far from an ancient ocean known as the Tethys Sea.
The fossil consists of a complete skull of an archaeocyte, an extinct group of ancestors of modern cetaceans. Although limited to a skull, the Pakicetus fossil provides precious details on the origins of cetaceans. The skull is cetacean-like but its jawbones lack the enlarged space that is filled with fat or oil and used for receiving underwater sound in modern whales. Pakicetus probably detected sound through the ear opening as in land mammals. The skull also lacks a blowhole, another cetacean adaptation for diving. Other features, however, show experts that Pakicetus is a transitional form between a group of extinct flesh- eating mammals, the mesonychids, and cetaceans. It has been suggested that Pakicetus fed on fish in shallow water and was not yet adapted for life in the open ocean. It probably bred and gave birth on land.
Another major discovery was made in Egypt in 1989. Several skeletons of another early whale, Basilosaurus, were found in sediments left by the Tethys Sea and now exposed in the Sahara desert. This whale lived around 40 million years ago, 12 million years after Pakicetus. Many incomplete skeletons were found but they included, for the first time in an archaeocyte, a complete hind leg that features a foot with three tiny toes. Such legs would have been far too small to have supported the 50-foot-long Basilosaurus on land. Basilosaurus was undoubtedly a fully marine whale with possibly nonfunctional, or vestigial, hind legs.
An even more exciting find was reported in 1994, also from Pakistan. The now extinct whale Ambulocetus natans ("the walking whale that swam") lived in the Tethys Sea 49 million years ago. It lived around 3 million years after Pakicetus but 9 million before Basilosaurus. The fossil luckily includes a good portion of the hind legs. The legs were strong and ended in long feet very much like those of a modern pinniped. The legs were certainly functional both on land and at sea. The whale retained a tail and lacked a fluke, the major means of locomotion in modern cetaceans. The structure of the backbone shows, however, that Ambulocetus swam like modern whales by moving the rear portion of its body up and down, even though a fluke was missing. The large hind legs were used for propulsion in water. On land, where it probably bred and gave birth, Ambulocetus may have moved around very much like a modern sea lion. It was undoubtedly a whale that linked life on land with life at sea.
1. Fluke: the two parts that constitute the large triangular tail of a whale
2. Blowhole: a hole in the top of the head used for breathing
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Early CinemaThe cinema did not emerge as a form of mass consumption until its technology evolved from the initial "peepshow" format to the point where images were projected on a screen in a darkened theater. In the peepshow format, a film was viewed through a small opening in a machine that was created for that purpose. Thomas Edison's peepshow device, the Kinetoscope, was introduced to the public in 1894. It was designed for use in Kinetoscope parlors, or arcades, which contained only a few individual machines and permitted only one customer to view a short, 50-foot film at any one time. The first Kinetoscope parlors contained five machines. For the price of 25 cents (or 5 cents per machine), customers moved from machine to machine to watch five different films (or, in the case of famous prizefights, successive rounds of a single fight).
These Kinetoscope arcades were modeled on phonograph parlors, which had proven successful for Edison several years earlier. In the phonograph parlors, customers listened to recordings through individual ear tubes, moving from one machine to the next to hear different recorded speeches or pieces of music. The Kinetoscope parlors functioned in a similar way. Edison was more interested in the sale of Kinetoscopes (for roughly $1,000 apiece) to these parlors than in the films that would be run in them (which cost approximately $10 to $15 each). He refused to develop projection technology, reasoning that if he made and sold projectors, then exhibitors would purchase only one machine-a projector-from him instead of several.
Exhibitors, however, wanted to maximize their profits, which they could do more readily by projecting a handful of films to hundreds of customers at a time (rather than one at a time) and by charging 25 to 50 cents admission. About a year after the opening of the first Kinetoscope parlor in 1894, showmen such as Louis and Auguste Lumiere, Thomas Armat and Charles Francis Jenkins, and Orville and Woodville Latham (with the assistance of Edison's former assistant, William Dickson) perfected projection devices. These early projection devices were used in vaudeville theaters, legitimate theaters, local town halls, makeshift storefront theaters, fairgrounds, and amusement parks to show films to a mass audience.
With the advent of projection in 1895-1896, motion pictures became the ultimate form of mass consumption. Previously, large audiences had viewed spectacles at the theater, where vaudeville, popular dramas, musical and minstrel shows, classical plays, lectures, and slide-and-lantern shows had been presented to several hundred spectators at a time. But the movies differed significantly from these other forms of entertainment, which depended on either live performance or (in the case of the slide-and-lantern shows) the active involvement of a master of ceremonies who assembled the final program.
Although early exhibitors regularly accompanied movies with live acts, the substance of the movies themselves is mass-produced, prerecorded material that can easily be reproduced by theaters with little or no active participation by the exhibitor. Even though early exhibitors shaped their film programs by mixing films and other entertainments together in whichever way they thought would be most attractive to audiences or by accompanying them with lectures, their creative control remained limited. What audiences came to see was the technological marvel of the movies; the lifelike reproduction of the commonplace motion of trains, of waves striking the shore, and of people walking in the street; and the magic made possible by trick photography and the manipulation of the camera.
With the advent of projection, the viewer's relationship with the image was no longer private, as it had been with earlier peepshow devices such as the Kinetoscope and the Mutoscope, which was a similar machine that reproduced motion by means of successive images on individual photographic cards instead of on strips of celluloid.It suddenly became public-an experience that the viewer shared with dozens, scores, and even hundreds of others. At the same time, the image that the spectator looked at expanded from the minuscule peepshow dimensions of 1 or 2 inches (in height) to the life-size proportions of 6 or 9 feet.
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ArchitectureArchitecture is the art and science of designing structures that organize and enclose space for practical and symbolic purposes. Because architecture grows out of human needs and aspirations, it clearly communicates cultural values. Of all the visual arts, architecture affects our lives most directly for it determines the character of the human environment in major ways.
Architecture is a three-dimensional form. It utilizes space, mass, texture, line, light, and color. To be architecture, a building must achieve a working harmony with a variety of elements. Humans instinctively seek structures that will shelter and enhance their way of life. It is the work of architects to create buildings that are not simply constructions but also offer inspiration and delight. Buildings contribute to human life when they provide shelter, enrich space, complement their site, suit the climate, and are economically feasible. The client who pays for the building and defines its function is an important member of the architectural team. The mediocre design of many contemporary buildings can be traced to both clients and architects.
In order for the structure to achieve the size and strength necessary to meet its purpose, architecture employs methods of support that, because they are based on physical laws, have changed little since people first discovered them—even while building materials have changed dramatically. The world’s architectural structures have also been devised in relation to the objective limitations of materials. Structures can be analyzed in terms of how they deal with downward forces created by gravity. They are designed to withstand the forces of compression (pushing together), tension (pulling apart), bending, or a combination of these in different parts of the structure.
Even development in architecture has been the result of major technological changes. Materials and methods of construction are integral parts of the design of architecture structures. In earlier times it was necessary to design structural systems suitable for the materials that were available, such as wood, stone, brick. Today technology has progressed to the point where it is possible to invent new building materials to suit the type of structure desired. Enormous changes in materials and techniques of construction within the last few generations have made it possible to enclose space with much greater ease and speed and with a minimum of material. Progress in this area can be measured by the difference in weight between buildings built now and those of comparable size built one hundred years ago.
Modern architectural forms generally have three separate components comparable to elements of the human body: a supporting skeleton or frame, an outer skin enclosing the interior spaces, and equipment, similar to the body’s vital organs and systems. The equipment includes plumbing, electrical wiring, hot water, and air-conditioning. Of course in early architecture—such as igloos and adobe structures—there was no such equipment, and the skeleton and skin were often one.
Much of the world’s great architecture has been constructed of stone because of its beauty, permanence, and availability. In the past, whole cities grew from the arduous task of cutting and piling stone upon. Some of the world’s finest stone architecture can be seen in the ruins of the ancient Inca city of Machu Picchu high in the eastern Andes Mountains of Peru. The doorways and windows are made possible by placing over the open spaces thick stone beams that support the weight from above. A structural invention had to be made before the physical limitations of stone could be overcome and new architectural forms could be created. That invention was the arch, a curved structure originally made of separate stone or brick segments. The arch was used by the early cultures of the Mediterranean area chiefly for underground drains, but it was the Romans who first developed and used the arch extensively in aboveground structures. Roman builders perfected the semicircular arch made of separate blocks of stone. As a method of spanning space, the arch can support greater weight than a horizontal beam. It works in compression to divert the weight above it out to the sides, where the weight is borne by the vertical elements on either side of the arch. The arch is among the many important structural breakthroughs that have characterized architecture throughout the centuries.
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Depletion of the Ogallala AquiferThe vast grasslands of the High Plains in the central United States were settled by farmers and ranchers in the 1880s. This region has a semiarid climate, and for 50 years after its settlement, it supported a low-intensity agricultural economy of cattle ranching and wheat farming. In the early twentieth century, however, it was discovered that much of the High Plains was underlain by a huge aquifer (a rock layer containing large quantities of groundwater). This aquifer was named the Ogallala aquifer after the Ogallala Sioux Indians, who once inhabited the region.
The Ogallala aquifer is a sandstone formation that underlies some 583,000 square kilometers of land extending from northwestern Texas to southern South Dakota. Water from rains and melting snows has been accumulating in the Ogallala for the past 30,000 years. Estimates indicate that the aquifer contains enough water to fill Lake Huron, but unfortunately, under the semiarid climatic conditions that presently exist in the region, rates of addition to the aquifer are minimal, amounting to about half a centimeter a year.
The first wells were drilled into the Ogallala during the drought years of the early 1930s. The ensuing rapid expansion of irrigation agriculture, especially from the 1950s onward, transformed the economy of the region. More than 100,000 wells now tap the Ogallala. Modern irrigation devices, each capable of spraying 4.5 million liters of water a day, have produced a landscape dominated by geometric patterns of circular green islands of crops. Ogallala water has enabled the High Plains region to supply significant amounts of the cotton, sorghum, wheat, and corn grown in the United States. In addition, 40 percent of American grain-fed beef cattle are fattened here.
This unprecedented development of a finite groundwater resource with an almost negligible natural recharge rate—that is, virtually no natural water source to replenish the water supply—has caused water tables in the region to fall drastically. In the 1930s, wells encountered plentiful water at a depth of about 15 meters; currently, they must be dug to depths of 45 to 60 meters or more. In places, the water table is declining at a rate of a meter a year, necessitating the periodic deepening of wells and the use of ever-more-powerful pumps. It is estimated that at current withdrawal rates, much of the aquifer will run dry within 40 years. The situation is most critical in Texas, where the climate is driest, the greatest amount of water is being pumped, and the aquifer contains the least water. It is projected that the remaining Ogallala water will, by the year 2030, support only 35 to 40 percent of the irrigated acreage in Texas that is supported in 1980.
The reaction of farmers to the inevitable depletion of the Ogallala varies. Many have been attempting to conserve water by irrigating less frequently or by switching to crops that require less water. Others, however, have adopted the philosophy that it is best to use the water while it is still economically profitable to do so and to concentrate on high-value crops such as cotton. The incentive of the farmers who wish to conserve water is reduced by their knowledge that many of their neighbors are profiting by using great amounts of water, and in the process are drawing down the entire region’s water supplies.
In the face of the upcoming water supply crisis, a number of grandiose schemes have been developed to transport vast quantities of water by canal or pipeline from the Mississippi, the Missouri, or the Arkansas rivers. Unfortunately, the cost of water obtained through any of these schemes would increase pumping costs at least tenfold, making the cost of irrigated agricultural products from the region uncompetitive on the national and international markets. Somewhat more promising have been recent experiments for releasing capillary water (water in the soil) above the water table by injecting compressed air into the ground. Even if this process proves successful, however, it would almost triple water costs. Genetic engineering also may provide a partial solution, as new strains of drought-resistant crops continue to be developed. Whatever the final answer to the water crisis may be, it is evident that within the High Plains, irrigation water will never again be the abundant, inexpensive resource it was during the agricultural boom years of the mid-twentieth century.
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The Long Term Stability of EcosystemsPlant communities assemble themselves flexibly, and their particular structure depends on the specific history of the area. Ecologists use the term “succession” to refer to the changes that happen in plant communities and ecosystems over time. The first community in a succession is called a pioneer community, while the long-lived community at the end of succession is called a climax community. Pioneer and successional plant communities are said to change over periods from 1 to 500 years. These changes—in plant numbers and the mix of species—are cumulative. Climax communities themselves change but over periods of time greater than about 500 years.
An ecologist who studies a pond today may well find it relatively unchanged in a year’s time. Individual fish may be replaced, but the number of fish will tend to be the same from one year to the next. We can say that the properties of an ecosystem are more stable than the individual organisms that compose the ecosystem.
At one time, ecologists believed that species diversity made ecosystems stable. They believed that the greater the diversity the more stable the ecosystem. Support for this idea came from the observation that long-lasting climax communities usually have more complex food webs and more species diversity than pioneer communities. Ecologists concluded that the apparent stability of climax ecosystems depended on their complexity. To take an extreme example, farmlands dominated by a single crop are so unstable that one year of bad weather or the invasion of a single pest can destroy the entire crop. In contrast, a complex climax community, such as a temperate forest, will tolerate considerable damage from weather to pests.
The question of ecosystem stability is complicated, however. The first problem is that ecologists do not all agree what “stability” means. Stability can be defined as simply lack of change. In that case, the climax community would be considered the most stable, since, by definition, it changes the least over time. Alternatively, stability can be defined as the speed with which an ecosystem returns to a particular form following a major disturbance, such as a fire. This kind of stability is also called resilience. In that case, climax communities would be the most fragile and the least stable, since they can require hundreds of years to return to the climax state.
Even the kind of stability defined as simple lack of change is not always associated with maximum diversity. At least in temperate zones, maximum diversity is often found in mid-successional stages, not in the climax community. Once a redwood forest matures, for example, the kinds of species and the number of individuals growing on the forest floor are reduced. In general, diversity, by itself, does not ensure stability. Mathematical models of ecosystems likewise suggest that diversity does not guarantee ecosystem stability—just the opposite, in fact. A more complicated system is, in general, more likely than a simple system to break down. A fifteen-speed racing bicycle is more likely to break down than a child’s tricycle.
Ecologists are especially interested to know what factors contribute to the resilience of communities because climax communities all over the world are being severely damaged or destroyed by human activities. The destruction caused by the volcanic explosion of Mount St. Helens, in the northwestern United States, for example, pales in comparison to the destruction caused by humans. We need to know what aspects of a community are most important to the community’s resistance to destruction, as well as its recovery.
Many ecologists now think that the relative long-term stability of climax communities comes not from diversity but from the “patchiness” of the environment, an environment that varies from place to place supports more kinds of organisms than an environment that is uniform. A local population that goes extinct is quickly replaced by immigrants from an adjacent community. Even if the new population is of a different species, it can approximately fill the niche vacated by the extinct population and keep the food web intact.
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Deer Populations of the Puget SoundTwo species of deer have been prevalent in the Puget Sound area of Washington State in the Pacific Northwest of the United States. The black-tailed deer, a lowland, west-side cousin of the mule deer of eastern Washington, is now the most common. The other species, the Columbian white-tailed deer, in earlier times was common in the open prairie country; it is now restricted to the low, marshy islands and flood plains along the lower Columbia River.
Nearly any kind of plant of the forest understory can be part of a deer's diet. Where the forest inhibits the growth of grass and other meadow plants, the black-tailed deer browses on huckleberry, salal, dogwood, and almost any other shrub or herb. But this is fair-weather feeding. What keeps the black-tailed deer alive in the harsher seasons of plant decay and dormancy? One compensation for not hibernating is the built-in urge to migrate. Deer may move from high-elevation browse areas in summer down to the lowland areas in late fall. Even with snow on the ground, the high bushy understory is exposed; also snow and wind bring down leafy branches of cedar, hemlock, red alder, and other arboreal fodder.
The numbers of deer have fluctuated markedly since the entry of Europeans into Puget Sound country. The early explorers and settlers told of abundant deer in the early 1800s and yet almost in the same breath bemoaned the lack of this succulent game animal. Famous explorers of the north American frontier, Lewis and Clark arrived at the mouth of the Columbia River on November 14, 1805, in nearly starved circumstances. They had experienced great difficulty finding game west of the Rockies and not until the second of December did they kill their first elk. To keep 40 people alive that winter, they consumed approximately 150 elk and 20 deer. And when game moved out of the lowlands in early spring, the expedition decided to return east rather than face possible starvation. Later on in the early years of the nineteenth century, when Fort Vancouver became the headquarters of the Hudson's Bay Company, deer populations continued to fluctuate. David Douglas, Scottish botanical explorer of the 1830s, found a disturbing change in the animal life around the fort during the period between his first visit in 1825 and his final contact with the fort in 1832. A recent Douglas biographer states:" The deer which once picturesquely dotted the meadows around the fort were gone , hunted to extermination in order to protect the crops."
Reduction in numbers of game should have boded ill for their survival in later times. A worsening of the plight of deer was to be expected as settlers encroached on the land, logging, burning, and clearing, eventually replacing a wilderness landscape with roads, cities, towns, and factories. No doubt the numbers of deer declined still further. Recall the fate of the Columbian white-tailed deer, now in a protected status. But for the black-tailed deer, human pressure has had just the opposite effect. Wildlife zoologist Helmut Buechner(1953), in reviewing the nature of biotic changes in Washington through recorded time, says that "since the early 1940s, the state has had more deer than at any other time in its history, the winter population fluctuating around approximately 320,000 deer (mule and black-tailed deer), which will yield about 65,000 of either sex and any age annually for an indefinite period."
The causes of this population rebound are consequences of other human actions. First, the major predators of deer—wolves, cougar, and lynx—have been greatly reduced in numbers. Second, conservation has been insured by limiting times for and types of hunting. But the most profound reason for the restoration of high population numbers has been the fate of the forests. Great tracts of lowland country deforested by logging, fire, or both have become ideal feeding grounds of deer. In addition to finding an increase of suitable browse, like huckleberry and vine maple, Arthur Einarsen, longtime game biologist in the Pacific Northwest, found quality of browse in the open areas to be substantially more nutritive. The protein content of shade-grown vegetation, for example, was much lower than that for plants grown in clearings.
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Cave Art in EuropeThe earliest discovered traces of art are beads and carvings, and then paintings, from sites dating back to the Upper Paleolithic period. We might expect that early artistic efforts would be crude, but the cave paintings of Spain and southern France show a marked degree of skill. So do the naturalistic paintings on slabs of stone excavated in southern Africa. Some of those slabs appear to have been painted as much as 28,000 years ago, which suggests that painting in Africa is as old as painting in Europe. But painting may be even older than that. The early Australians may have painted on the walls of rock shelters and cliff faces at least 30,000 years ago, and maybe as much as 60,000 years ago.
The researchers Peter Ucko and Andree Rosenfeld identified three principal locations of paintings in the caves of western Europe: (1) in obviously inhabited rock shelters and cave entrances; (2) in galleries immediately off the inhabited areas of caves; and (3) in the inner reaches of caves, whose difficulty of access has been interpreted by some as a sign that magical-religious activities were performed there.
The subjects of the paintings are mostly animals. The paintings rest on bare walls, with no backdrops or environmental trappings. Perhaps, like many contemporary peoples, Upper Paleolithic men and women believed that the drawing of a human image could cause death or injury, and if that were indeed their belief, it might explain why human figures are rarely depicted in cave art. Another explanation for the focus on animals might be that these people sought to improve their luck at hunting. This theory is suggested by evidence of chips in the painted figures, perhaps made by spears thrown at the drawings. But if improving their hunting luck was the chief motivation for the paintings, it is difficult to explain why only a few show signs of having been speared. Perhaps the paintings were inspired by the need to increase the supply of animals. Cave art seems to have reached a peak toward the end of the Upper Paleolithic period, when the herds of game were decreasing.
The particular symbolic significance of the cave paintings in southwestern France is more explicitly revealed, perhaps, by the results of a study conducted by researchers Patricia Rice and Ann Paterson. The data they present suggest that the animals portrayed in the cave paintings were mostly the ones that the painters preferred for meat and for materials such as hides. For example, wild cattle (bovines) and horses are portrayed more often than we would expect by chance, probably because they were larger and heavier (meatier) than other animals in the environment. In addition, the paintings mostly portray animals that the painters may have feared the most because of their size, speed, natural weapons such as tusks and horns, and the unpredictability of their behavior. That is, mammoths, bovines, and horses are portrayed more often than deer and reindeer. Thus, the paintings are consistent with the idea that the art is related to the importance of hunting in the economy of Upper Paleolithic people. Consistent with this idea, according to the investigators, is the fact that the art of the cultural period that followed the Upper Paleolithic also seems to reflect how people got their food. But in that period, when getting food no longer depended on hunting large game animals (because they were becoming extinct), the art ceased to focus on portrayals of animals.
Upper Paleolithic art was not confined to cave paintings. Many shafts of spears and similar objects were decorated with figures of animals. The anthropologist Alexander Marshack has an interesting interpretation of some of the engravings made during the Upper Paleolithic. He believes that as far back as 30,000 B.C., hunters may have used a system of notation, engraved on bone and stone, to mark phases of the Moon. If this is true, it would mean that Upper Paleolithic people were capable of complex thought and were consciously aware of their environment. In addition to other artworks, figurines representing the human female in exaggerated form have also been found at Upper Paleolithic sites. It has been suggested that these figurines were an ideal type or an expression of a desire for fertility.
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Petroleum ResourcesPetroleum, consisting of crude oil and natural gas, seems to originate from organic matter in marine sediment. Microscopic organisms settle to the seafloor and accumulate in marine mud. The organic matter may partially decompose, using up the dissolved oxygen in the sediment. As soon as the oxygen is gone, decay stops and the remaining organic matter is preserved.
Continued sedimentation—the process of deposits’ settling on the sea bottom—buries the organic matter and subjects it to higher temperatures and pressures, which convert the organic matter to oil and gas. As muddy sediments are pressed together, the gas and small droplets of oil may be squeezed out of the mud and may move into sandy layers nearby. Over long periods of time (millions of years), accumulations of gas and oil can collect in the sandy layers. Both oil and gas are less dense than water, so they generally tend to rise upward through water-saturated rock and sediment.
Oil pools are valuable underground accumulations of oil, and oil fields are regions underlain by one or more oil pools. When an oil pool or field has been discovered, wells are drilled into the ground. Permanent towers, called derricks, used to be built to handle the long sections of drilling pipe. Now portable drilling machines are set up and are then dismantled and removed. When the well reaches a pool, oil usually rises up the well because of its density difference with water beneath it or because of the pressure of expanding gas trapped above it. Although this rise of oil is almost always carefully controlled today, spouts of oil, or gushers, were common in the past. Gas pressure gradually dies out, and oil is pumped from the well. Water or steam may be pumped down adjacent wells to help push the oil out. At a refinery, the crude oil from underground is separated into natural gas, gasoline, kerosene, and various oils. Petrochemicals such as dyes, fertilizer, and plastic are also manufactured from the petroleum.
As oil becomes increasingly difficult to find, the search for it is extended into more-hostile environments. The development of the oil field on the North Slope of Alaska and the construction of the Alaska pipeline are examples of the great expense and difficulty involved in new oil discoveries. Offshore drilling platforms extend the search for oil to the ocean’s continental shelves—those gently sloping submarine regions at the edges of the continents. More than one-quarter of the world’s oil and almost one-fifth of the world’s natural gas come from offshore, even though offshore drilling is six to seven times more expensive than drilling on land. A significant part of this oil and gas comes from under the North Sea between Great Britain and Norway.
Of course, there is far more oil underground than can be recovered. It may be in a pool too small or too far from a potential market to justify the expense of drilling. Some oil lies under regions where drilling is forbidden, such as national parks or other public lands. Even given the best extraction techniques, only about 30 to 40 percent of the oil in a given pool can be brought to the surface. The rest is far too difficult to extract and has to remain underground.
Moreover, getting petroleum out of the ground and from under the sea and to the consumer can create environmental problems anywhere along the line. Pipelines carrying oil can be broken by faults or landslides, causing serious oil spills. Spillage from huge oil-carrying cargo ships, called tankers, involved in collisions or accidental groundings (such as the one off Alaska in 1989) can create oil slicks at sea. Offshore platforms may also lose oil, creating oil slicks that drift ashore and foul the beaches, harming the environment. Sometimes, the ground at an oil field may subside as oil is removed. The Wilmington field near Long Beach, California, has subsided nine meters in 50 years; protective barriers have had to be built to prevent seawater from flooding the area. Finally, the refining and burning of petroleum and its products can cause air pollution. Advancing technology and strict laws, however, are helping control some of these adverse environmental effects.
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Minerals and PlantsResearch has shown that certain minerals are required by plants for normal growth and development. The soil is the source of these minerals, which are absorbed by the plant with the water from the soil. Even nitrogen, which is a gas in its elemental state, is normally absorbed from the soil as nitrate ions. Some soils are notoriously deficient in micro nutrients and are therefore unable to support most plant life. So-called serpentine soils, for example, are deficient in calcium, and only plants able to tolerate low levels of this mineral can survive. In modern agriculture, mineral depletion of soils is a major concern, since harvesting crops interrupts the recycling of nutrients back to the soil.
Mineral deficiencies can often be detected by specific symptoms such as chlorosis (loss of chlorophyll resulting in yellow or white leaf tissue), necrosis (isolated dead patches), anthocyanin formation (development of deep red pigmentation of leaves or stem), stunted growth, and development of woody tissue in an herbaceous plant. Soils are most commonly deficient in nitrogen and phosphorus. Nitrogen-deficient plants exhibit many of the symptoms just described. Leaves develop chlorosis; stems are short and slender, and anthocyanin discoloration occurs on stems, petioles, and lower leaf surfaces. Phosphorus-deficient plants are often stunted, with leaves turning a characteristic dark green, often with the accumulation of anthocyanin. Typically, older leaves are affected first as the phosphorus is mobilized to young growing tissue. Iron deficiency is characterized by chlorosis between veins in young leaves.
Much of the research on nutrient deficiencies is based on growing plants hydroponically, that is, in soilless liquid nutrient solutions. This technique allows researchers to create solutions that selectively omit certain nutrients and then observe the resulting effects on the plants. Hydroponics has applications beyond basic research, since it facilitates the growing of greenhouse vegetables during winter. Aeroponics, a technique in which plants are suspended and the roots misted with a nutrient solution, is another method for growing plants without soil.
While mineral deficiencies can limit the growth of plants, an overabundance of certain minerals can be toxic and can also limit growth. Saline soils, which have high concentrations of sodium chloride and other salts, limit plant growth, and research continues to focus on developing salt-tolerant varieties of agricultural crops. Research has focused on the toxic effects of heavy metals such as lead, cadmium, mercury, and aluminum; however, even copper and zinc, which are essential elements, can become toxic in high concentrations. Although most plants cannot survive in these soils, certain plants have the ability to tolerate high levels of these minerals.
Scientists have known for some time that certain plants, called hyperaccumulators, can concentrate minerals at levels a hundredfold or greater than normal. A survey of known hyperaccumulators identified that 75 percent of them amassed nickel, cobalt, copper, zinc, manganese, lead, and cadmium are other minerals of choice. Hyperaccumulators run the entire range of the plant world. They may be herbs, shrubs, or trees. Many members of the mustard family, spurge family, legume family, and grass family are top hyperaccumulators. Many are found in tropical and subtropical areas of the world, where accumulation of high concentrations of metals may afford some protection against plant-eating insects and microbial pathogens.
Only recently have investigators considered using these plants to clean up soil and waste sites that have been contaminated by toxic levels of heavy metals–an environmentally friendly approach known as phytoremediation. This scenario begins with the planting of hyperaccumulating species in the target area, such as an abandoned mine or an irrigation pond contaminated by runoff. Toxic minerals would first be absorbed by roots but later relocated to the stem and leaves. A harvest of the shoots would remove the toxic compounds off site to be burned or composted to recover the metal for industrial uses. After several years of cultivation and harvest, the site would be restored at a cost much lower than the price of excavation and reburial, the standard practice for remediation of contaminated soils. For examples, in field trials, the plant alpine pennycress removed zinc and cadmium from soils near a zinc smelter, and Indian mustard, native to Pakistan and India, has been effective in reducing levels of selenium salts by 50 percent in contaminated soils.
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The Origin of the Pacific Island PeopleThe greater Pacific region, traditionally called Oceania, consists of three cultural areas: Melanesia, Micronesia, and Polynesia. Melanesia, in the southwest Pacific, contains the large islands of New Guinea, the Solomons, Vanuatu, and New Caledonia. Micronesia, the area north of Melanesia, consists primarily of small scattered islands. Polynesia is the central Pacific area in the great triangle defined by Hawaii, Easter Island, and New Zealand. Before the arrival of Europeans, the islands in the two largest cultural areas, Polynesia and Micronesia, together contained a population estimated at 700,000.
Speculation on the origin of these Pacific islanders began as soon as outsiders encountered them, in the absence of solid linguistic, archaeological, and biological data, many fanciful and mutually exclusive theories were devised. Pacific islanders are variously thought to have come from North America, South America, Egypt, Israel, and India, as well as Southeast Asia. Many older theories implicitly deprecated the navigational abilities and overall cultural creativity of the Pacific islanders. For example, British anthropologists G. Elliot Smith and W. J. Perry assumed that only Egyptians would have been skilled enough to navigate and colonize the Pacific. They inferred that the Egyptians even crossed the Pacific to found the great civilizations of the New World (North and South America). In 1947 Norwegian adventurer Thor Heyerdahl drifted on a balsa-log raft westward with the winds and currents across the Pacific from South America to prove his theory that Pacific islanders were Native Americans (also called American Indians). Later Heyerdahl suggested that the Pacific was peopled by three migrations: by Native Americans from the Pacific Northwest of North America drifting to Hawaii, by Peruvians drifting to Easter Island, and by Melanesians. In 1969 he crossed the Atlantic in an Egyptian-style reed boat to prove Egyptian influences in the Americas. Contrary to these theorists, the overwhelming evidence of physical anthropology, linguistics, and archaeology shows that the Pacific islanders came from Southeast Asia and were skilled enough as navigators to sail against the prevailing winds and currents.
The basic cultural requirements for the successful colonization of the Pacific islands include the appropriate boat-building, sailing, and navigation skills to get to the islands in the first place, domesticated plants and gardening skills suited to often marginal conditions, and a varied inventory of fishing implements and techniques. It is now generally believed that these prerequisites originated with peoples speaking Austronesian languages (a group of several hundred related languages) and began to emerge in Southeast Asia by about 5000 B.C.E. The culture of that time, based on archaeology and linguistic reconstruction, is assumed to have had a broad inventory of cultivated plants including taro, yarns, banana, sugarcane, breadfruit, coconut, sago, and rice. Just as important, the culture also possessed the basic foundation for an effective maritime adaptation, including outrigger canoes and a variety of fishing techniques that could be effective for overseas voyaging.
Contrary to the arguments of some that much of the pacific was settled by Polynesians accidentally marooned after being lost and adrift, it seems reasonable that this feat was accomplished by deliberate colonization expeditions that set out fully stocked with food and domesticated plants and animals. Detailed studies of the winds and currents using computer simulations suggest that drifting canoes would have been a most unlikely means of colonizing the Pacific. These expeditions were likely driven by population growth and political dynamics on the home islands, as well as the challenge and excitement of exploring unknown waters.
Because all Polynesians, Micronesians, and many Melanesians speak Austronesian languages and grow crops derived from Southeast Asia, all these peoples most certainly derived from that region and not the New World or elsewhere. The undisputed pre-Columbian presence in Oceania of the sweet potato, which is a New World domesticate, has sometimes been used to support Heyerdahl’s “American Indians in the Pacific” theories. However, this is one plant out of a long list of Southeast Asian domesticates. As Patrick Kirch, an American anthropologist, points out, rather than being brought by rafting South Americans, sweet potatoes might just have easily been brought back by returning Polynesian navigators who could have reached the west coast of South America.
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The Cambrian ExplosionThe geologic timescale is marked by significant geologic and biological events, including the origin of Earth about 4.6 billion years ago, the origin of life about 3.5 billion years ago, the origin of eukaryotic life-forms (living things that have cells with true nuclei) about 1.5 billion years ago, and the origin of animals about 0.6 billion years ago. The last event marks the beginning of the Cambrian period. Animals originated relatively late in the history of Earth—in only the last 10 percent of Earth’s history. During a geologically brief 100-million-year period, all modern animal groups (along with other animals that are now extinct) evolved. This rapid origin and diversification of animals is often referred to as “the Cambrian explosion.”
Scientists have asked important questions about this explosion for more than a century. Why did it occur so late in the history of Earth? The origin of multicellular forms of life seems a relatively simple step compared to the origin of life itself. Why does the fossil record not document the series of evolutionary changes during the evolution of animals? Why did animal life evolve so quickly? Paleontologists continue to search the fossil record for answers to these questions.
One interpretation regarding the absence of fossils during this important 100-million-year period is that early animals were soft bodied and simply did not fossilize. Fossilization of soft-bodied animals is less likely than fossilization of hard-bodied animals, but it does occur. Conditions that promote fossilization of soft-bodied animals include very rapid covering by sediments that create an environment that discourages decomposition. In fact, fossil beds containing soft-bodied animals have been known for many years.
The Ediacara fossil formation, which contains the oldest known animal fossils, consists exclusively of soft-bodied forms. Although named after a site in Australia, the Ediacara formation is worldwide in distribution and dates to Precambrian times. This 700-million-year-old formation gives few clues to the origins of modern animals, however, because paleontologists believe it represents an evolutionary experiment that failed. It contains no ancestors of modern animal groups.
A slightly younger fossil formation containing animal remains is the Tommotian formation, named after a locale in Russia. It dates to the very early Cambrian period, and it also contains only soft-bodied forms. At one time, the animals present in these fossil beds were assigned to various modern animal groups, but most paleontologists now agree that all Tommotian fossils represent unique body forms that arose in the early Cambrian period and disappeared before the end of the period, leaving no descendants in modern animal groups.
A third fossil formation containing both soft-bodied and hard-bodied animals provides evidence of the result of the Cambrian explosion. This fossil formation, called the Burgess Shale, is in Yoho National Park in the Canadian Rocky Mountains of British Columbia. Shortly after the Cambrian explosion, mud slides rapidly buried thousands of marine animals under conditions that favored fossilization. These fossil beds provide evidence of about 32 modern animal groups, plus about 20 other animal body forms that are so different from any modern animals that they cannot be assigned to any one of the modern groups. These unassignable animals include a large swimming predator called Anomalocaris and a soft-bodied animal called Wiwaxia, which ate detritus or algae. The Burgess Shale formation also has fossils of many extinct representatives of modern animal groups. For example, a well-known Burgess Shale animal called Sidneyia is a representative of a previously unknown group of arthropods (a category of animals that includes insects, spiders, mites, and crabs).
Fossil formations like the Burgess Shale show that evolution cannot always be thought of as a slow progression. The Cambrian explosion involved rapid evolutionary diversification, followed by the extinction of many unique animals. Why was this evolution so rapid? No one really knows. Many zoologists believe that it was because so many ecological niches were available with virtually no competition from existing species. Will zoologists ever know the evolutionary sequences in the Cambrian explosion? Perhaps another ancient fossil bed of soft-bodied animals from 600-million-year-old seas is awaiting discovery.
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Powering the Industrial RevolutionIn Britain one of the most dramatic changes of the Industrial Revolution was the harnessing of power. Until the reign of George Ⅲ(1760-1820), available sources of power for work and travel had not increased since the Middle Ages. There were three sources of power: animal or human muscles; the wind, operating on sail or windmill; and running water. Only the last of these was suited at all to the continuous operating of machines, and although waterpower abounded in Lancashire and Scotland and ran grain mills as well as textile mills, it had one great disadvantage: streams flowed where nature intended them to, and water-driven factories had to be located on their banks whether or not the location was desirable for other reasons. Furthermore, even the most reliable waterpower varied with the seasons and disappeared in a drought. The new age of machinery, in short, could not have been born without a new source of both movable and constant power.
The source had long been known but not exploited. Early in the eighteenth century, a pump had come into use in which expanding steam raised a piston in a cylinder, and atmospheric pressure brought it down again when the steam condensed inside the cylinder to form a vacuum. This “atmospheric engine,” invented by Thomas Savery and vastly improved by his partner, Thomas Newcomen, embodied revolutionary principles, but it was so slow and wasteful of fuel that it could not be employed outside the coal mines for which it had been designed. In the 1760s, James Watt perfected a separate condenser for the steam, so that the cylinder did not have to be cooled at every stroke; then he devised a way to make the piston turn a wheel and thus convert reciprocating (back and forth) motion into rotary motion. He thereby transformed an inefficient pump of limited use into a steam engine of a thousand uses. The final step came when steam was introduced into the cylinder to drive the piston backward as well as forward, thereby increasing the speed of the engine and cutting its fuel consumption.
Watt's steam engine soon showed what it could do. It liberated industry from dependence on running water. The engine eliminated water in the mines by driving efficient pumps, which made possible deeper and deeper mining. The ready availability of coal inspired William Murdoch during the 1790s to develop the first new form of nighttime illumination to be discovered in a millennium and a half. Coal gas rivaled smoky oil lamps and flickering candles, and early in the new century, well-to-do Londoners grew accustomed to gaslit houses and even streets. Iron manufacturers, which had starved for fuel while depending on charcoal, also benefited from ever-increasing supplies of coal: blast furnaces with steam-powered bellows turned out more iron and steel for the new machinery. Steam became the motive force of the Industrial Revolution as coal and iron ore were the raw materials.
By 1800 more than a thousand steam engines were in use in the British Isles, and Britain retained a virtual monopoly on steam engine production until the 1830s. Steam power did not merely spin cotton and roll iron; early in the new century, it also multiplied ten times over the amount of paper that a single worker could produce in a day. At the same time, operators of the first printing presses run by steam rather than by hand found it possible to produce a thousand pages in an hour rather than thirty. Steam also promised to eliminate a transportation problem not fully solved by either canal boats or turnpikes. Boats could carry heavy weights, but canals could not cross hilly terrain; turnpikes could cross the hills, but the roadbeds could not stand up under great weights. These problems needed still another solution, and the ingredients for it lay close at hand. In some industrial regions, heavily laden wagons, with flanged wheels, were being hauled by horses along metal rails; and the stationary steam engine was puffing in the factory and mine. Another generation passed before inventors succeeded in combining these ingredients, by putting the engine on wheels and the wheels on the rails, so as to provide a machine to take the place of the horse. Thus the railroad age sprang from what had already happened in the eighteenth century.
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William SmithIn 1769 in a little town in Oxfordshire, England, a child with the very ordinary name of William Smith was born into the poor family of a village blacksmith. He received rudimentary village schooling, but mostly he roamed his uncle's farm collecting the fossils that were so abundant in the rocks of the Cotswold hills. When he grew older, William Smith taught himself surveying from books he bought with his small savings, and at the age of eighteen he was apprenticed to a surveyor of the local parish. He then proceeded to teach himself geology, and when he was twenty-four, he went to work for the company that was excavating the Somerset Coal Canal in the south of England.
This was before the steam locomotive, and canal building was at its height. The companies building the canals to transport coal needed surveyors to help them find the coal deposits worth mining as well as to determine the best courses for the canals. This job gave Smith an opportunity to study the fresh rock outcrops created by the newly dug canal. He later worked on similar jobs across the length and breadth of England, all the while studying the newly revealed strata and collecting all the fossils he could find. Smith used mail coaches to travel as much as 10,000 miles per year. In 1815 he published the first modern geological map, “A Map of the Strata of England and Wales with a Part of Scotland,” a map so meticulously researched that it can still be used today.
In 1831 when Smith was finally recognized by the Geological Society of London as the “father of English geology,” it was not only for his maps but also for something even more important. Ever since people had begun to catalog the strata in particular outcrops, there had been the hope that these could somehow be used to calculate geological time. But as more and more accumulations of strata were cataloged in more and more places, it became clear that the sequences of rocks sometimes differed from region to region and that no rock type was ever going to become a reliable time marker throughout the world. Even without the problem of regional differences, rocks present a difficulty as unique time markers. Quartz is quartz—a silicon ion surrounded by four oxygen ions—there’s no difference at all between two-million-year-old Pleistocene quartz and Cambrian quartz created over 500 million years ago.
As he collected fossils from strata throughout England, Smith began to see that the fossils told a different story from the rocks. Particularly in the younger strata, the rocks were often so similar that he had trouble distinguishing the strata, but he never had trouble telling the fossils apart. While rock between two consistent strata might in one place be shale and in another sandstone, the fossils in that shale or sandstone were always the same. Some fossils endured through so many millions of years that they appear in many strata, but others occur only in a few strata, and a few species had their births and extinctions within one particular stratum. Fossils are thus identifying markers for particular periods in Earth's history.
Not only could Smith identify rock strata by the fossils they contained, he could also see a pattern emerging: certain fossils always appear in more ancient sediments, while others begin to be seen as the strata become more recent. By following the fossils, Smith was able to put all the strata of England's earth into relative temporal sequence. About the same time, Georges Cuvier made the same discovery while studying the rocks around Paris. Soon it was realized that this principle of faunal (animal) succession was valid not only in England or France but virtually everywhere. It was actually a principle of floral succession as well, because plants showed the same transformation through time as did fauna. Limestone may be found in the Cambrian or—300 million years later—in the Jurassic strata, but a trilobite—the ubiquitous marine arthropod that had its birth in the Cambrian—will never be found in Jurassic strata, nor a dinosaur in the Cambrian.
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Infantile AmnesiaWhat do you remember about your life before you were three? Few people can remember anything that happened to them in their early years. Adults' memories of the next few years also tend to be scanty. Most people remember only a few events—usually ones that were meaningful and distinctive, such as being hospitalized or a sibling’s birth.
How might this inability to recall early experiences be explained? The sheer passage of time does not account for it; adults have excellent recognition of pictures of people who attended high school with them 35 years earlier. Another seemingly plausible explanation—that infants do not form enduring memories at this point in development—also is incorrect. Children two and a half to three years old remember experiences that occurred in their first year, and eleven month olds remember some events a year later. Nor does the hypothesis that infantile amnesia reflects repression—or holding back—of sexually charged episodes explain the phenomenon. While such repression may occur, people cannot remember ordinary events from the infant and toddler periods either.
Three other explanations seem more promising. One involves physiological changes relevant to memory. Maturation of the frontal lobes of the brain continues throughout early childhood, and this part of the brain may be critical for remembering particular episodes in ways that can be retrieved later. Demonstrations of infants’ and toddlers' long-term memory have involved their repeating motor activities that they had seen or done earlier, such as reaching in the dark for objects, putting a bottle in a doll’s mouth, or pulling apart two pieces of a toy. The brain’s level of physiological maturation may support these types of memories, but not ones requiring explicit verbal descriptions.
A second explanation involves the influence of the social world on children’s language use. Hearing and telling stories about events may help children store information in ways that will endure into later childhood and adulthood. Through hearing stories with a clear beginning, middle, and ending children may learn to extract the gist of events in ways that they will be able to describe many years later. Consistent with this view, parents and children increasingly engage in discussions of past events when children are about three years old. However, hearing such stories is not sufficient for younger children to form enduring memories. Telling such stories to two year olds does not seem to produce long-lasting verbalizable memories.
A third likely explanation for infantile amnesia involves incompatibilities between the ways in which infants encode information and the ways in which older children and adults retrieve it. Whether people can remember an event depends critically on the fit between the way in which they earlier encoded the information and the way in which they later attempt to retrieve it. The better able the person is to reconstruct the perspective from which the material was encoded, the more likely that recall will be successful.
This view is supported by a variety of factors that can create mismatches between very young children's encoding and older children's and adults' retrieval efforts. The world looks very different to a person whose head is only two or three feet above the ground than to one whose head is five or six feet above it. Older children and adults often try to retrieve the names of things they saw, but infants would not have encoded the information verbally. General knowledge of categories of events such as a birthday party or a visit to the doctor's office helps older individuals encode their experiences, but again, infants and toddlers are unlikely to encode many experiences within such knowledge structures.
These three explanations of infantile amnesia are not mutually exclusive; indeed, they support each other. Physiological immaturity may be part of why infants and toddlers do not form extremely enduring memories, even when they hear stories that promote such remembering in preschoolers. Hearing the stories may lead preschoolers to encode aspects of events that allow them to form memories they can access as adults. Conversely, improved encoding of what they hear may help them better understand and remember stories and thus make the stories more useful for remembering future events. Thus, all three explanations—physiological maturation, hearing and producing stories about past events, and improved encoding of key aspects of events—seem likely to be involved in overcoming infantile amnesia.
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The Geologic History of the MediterraneanIn 1970 geologists Kenneth J. Hsu and William B.F. Ryan were collecting research data while aboard the oceanographic research vessel Glomar Challenger. An objective of this particular cruise was to investigate the floor of the Mediterranean and to resolve questions about its geologic history. One question was related to evidence that the invertebrate fauna (animals without spines) of the Mediterranean had changed abruptly about 6 million years ago. Most of the older organisms were nearly wiped out, although a few hardy species survived. A few managed to migrate into the Atlantic. Somewhat later, the migrants returned, bringing new species with them. Why did the near extinction and migrations occur?
Another task for the Glomar Challenger’s scientists was to try to determine the origin of the domelike masses buried deep beneath the Mediterranean seafloor. These structures had been detected years earlier by echo-sounding instruments, but they had never been penetrated in the course of drilling. Were they salt domes such as are common along the United States Gulf Coast, and if so, why should there have been so much solid crystalline salt beneath the floor of the Mediterranean?
With question such as these clearly before them, the scientists aboard the Glomar Challenger processed to the Mediterranean to search for the answers. On August 23, 1970, they recovered a sample. The sample consisted of pebbles of hardened sediment that had once been soft, deep-sea mud, as well as granules of gypsum and fragments of volcanic rock. Not a single pebble was found that might have indicated that the pebbles came from the nearby continent. In the days following, samples of solid gypsum were repeatedly brought on deck as drilling operations penetrated the seafloor. Furthermore, the gypsum was found to possess peculiarities of composition and structure that suggested it had formed on desert flats. Sediment above and below the gypsum layer contained tiny marine fossils, indicating open-ocean conditions. As they drilled into the central and deepest part of the Mediterranean basin, the scientists took solid, shiny, crystalline salt from the core barrel. Interbedded with the salt were thin layers of what appeared to be windblown silt.
The time had come to formulate a hypothesis. The investigators theorized that about 20 million years ago, the Mediterranean was a broad seaway linked to the Atlantic by two narrow straits. Crustal movements closed the straits, and the landlocked Mediterranean began to evaporate. Increasing salinity caused by the evaporation resulted in the extermination of scores of invertebrate species. Only a few organisms especially tolerant of very salty conditions remained. As evaporation continued, the remaining brine (salt water) became so dense that the calcium sulfate of the hard layer was precipitated. In the central deeper part of the basin, the last of the brine evaporated to precipitate more soluble sodium chloride (salt). Later, under the weight of overlying sediments, this salt flowed plastically upward to form salt domes. Before this happened, however, the Mediterranean was a vast desert 3,000 meters deep. Then, about 5.5 million years ago came the deluge. As a result of crustal adjustments and faulting, the Strait of Gibraltar, where the Mediterranean now connects to the Atlantic, opened, and water cascaded spectacularly back into the Mediterranean. Turbulent waters tore into the hardened salt flats, broke them up, and ground them into the pebbles observed in the first sample taken by the Challenger. As the basin was refilled, normal marine organisms returned. Soon layer of oceanic ooze began to accumulate above the old hard layer.
The salt and gypsum, the faunal changes, and the unusual gravel provided abundant evidence that the Mediterranean was once a desert.
gypsum: a mineral made of calcium sulfate and water
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Ancient Rome and GreeceThere is a quality of cohesiveness about the Roman world that applied neither to Greece nor perhaps to any other civilization, ancient or modern. Like the stone of Roman wall, which were held together both by the regularity of the design and by that peculiarly powerful Roman cement, so the various parts of the Roman realm were bonded into a massive, monolithic entity by physical, organizational, and psychological controls. The physical bonds included the network of military garrisons, which were stationed in every province, and the network of stone-built roads that linked the provinces with Rome. The organizational bonds were based on the common principles of law and administration and on the universal army of officials who enforced common standards of conduct. The psychological controls were built on fear and punishment—on the absolute certainty that anyone or anything that threatened the authority of Rome would be utterly destroyed.
The source of Roman obsession with unity and cohesion may well have lain in the pattern of Rome’s early development. Whereas Greece had grown from scores of scattered cities, Rome grew from one single organism. While the Greek world had expanded along the Mediterranean seas lanes, the Roman world was assembled by territorial conquest. Of course, the contrast is not quite so stark: in Alexander the Great the Greeks had found the greatest territorial conqueror of all time; and the Romans, once they moved outside Italy, did not fail to learn the lessons of sea power. Yet the essential difference is undeniable. The key to the Greek world lay in its high-powered ships; the key to Roman power lay in its marching legions. The Greeks were wedded to the sea; the Romans, to the land. The Greek was a sailor at heart; the Roman, a landsman.
Certainly, in trying to explain the Roman phenomenon, one would have to place great emphasis on this almost instinct for the territorial imperative. Roman priorities lay in the organization, exploitation, and defense of their territory. In all probability it was the fertile plain of Latium, where the Latins who founded Rome originated, that created the habits and skills of landed settlement, landed property, landed economy, landed administration, and a land-based society. From this arose the Roman genius for military organization and orderly government. In turn, a deep attachment to the land, and to the stability which rural life engenders, fostered the Roman virtues: gravitas, a sense of responsibility, pietas, a sense of devotion to family and country, and iustitia, a sense of the natural order.
Modern attitudes to Roman civilization range from the infinitely impressed to the thoroughly disgusted. As always, there are the power worshippers, especially among historians, who are predisposed to admire whatever is strong, who feel more attracted to the might of Rome than to the subtlety of Greece. At the same time, there is a solid body of opinion that dislikes Rome. For many, Rome is at best the imitator and the continuator of Greece on a larger scale. Greek civilization had quality; Rome, mere quantity. Greece was original; Rome, derivative. Greece had style; Rome had money. Greece was the inventor; Rome, the research and development division. Such indeed was the opinion of some of the more intellectual Romans. “Had the Greeks held novelty in such disdain as we,” asked Horace in his epistle, “what work of ancient date would now exist?”
Rome’s debt to Greece was enormous. The Romans adopted Greek religion and moral philosophy. In literature, Greek writers were consciously used as models by their Latin successors. It was absolutely accepted that an educated Roman should be fluent in Greek. In speculative philosophy and the sciences, the Romans made virtually no advance on early achievements.
Yet it would be wrong to suggest that Rome was somehow a junior partner in Greco-Roman civilization. The Roman genius was projected into new spheres—especially into those of law, military organization, administration, and engineering. Moreover, the tensions that arose within the Roman state produced literary and artistic sensibilities of the highest order. It was no accident that many leading Roman soldiers and statesmen were writers of high caliber.
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Agriculture Iron and the Bantu PeoplesThere is evidence of agriculture in Africa prior to 3000 B.C. It may have developed independently, but many scholars believe that the spread of agriculture and iron throughout Africa linked it to the major centers of the Near East and Mediterranean world. The drying up of what is now the Sahara desert had pushed many peoples to the south into sub-Sahara Africa. These peoples settled at first in scattered hunting-and-gathering bands, although in some places near lakes and rivers, people who fished, with a more secure food supply, lived in larger population concentrations. Agriculture seems to have reached these people from the Near East, since the first domesticated crops were millets and sorghums whose origins are not African but west Asian. Once the idea of planting diffused, Africans began to develop their own crops, such as certain varieties of rice, and they demonstrated a continued receptiveness to new imports. The proposed areas of the domestication of African crops lie in a band that extends from Ethiopia across southern Sudan to West Africa. Subsequently, other crops, such as bananas, were introduced from Southeast Asia.
Livestock also came from outside Africa. Cattle were introduced from Asia, as probably were domestic sheep and goats. Horses were apparently introduced by the Hyksos invaders of Egypt (1780-1560 B.C.) and then spread across the Sudan to West Africa. Rock paintings in the Sahara indicate that horses and chariots were used to traverse the desert and that by 300-200 B.C., there were trade routes across the Sahara. Horses were adopted by peoples of the West African savannah, and later their powerful cavalry forces allowed them to carve out large empires. Finally, the camel was introduced around the first century A.D. This was an important innovation, because the camel’s abilities to thrive in harsh desert conditions and to carry large loads cheaply made it an effective and efficient means of transportation. The camel transformed the desert from a barrier into a still difficult, but more accessible, route of trade and communication.
Iron came from West Asia, although its routes of diffusion were somewhat different than those of agriculture. Most of Africa presents a curious case in which societies moved directly from a technology of stone to iron without passing through the intermediate stage of copper or bronze metallurgy, although some early copper-working sites have been found in West Africa. Knowledge of iron making penetrated into the forest and savannahs of West Africa at roughly the same time that iron making was reaching Europe. Evidence of iron making has been found in Nigeria, Ghana, and Mali.
This technological shift cause profound changes in the complexity of African societies. Iron represented power. In West Africa the blacksmith who made tools and weapons had an important place in society, often with special religious powers and functions. Iron hoes, which made the land more productive, and iron weapons, which made the warrior more powerful, had symbolic meaning in a number of West Africa societies. Those who knew the secrets of making iron gained ritual and sometimes political power.
Unlike in the Americas, where metallurgy was a very late and limited development, Africans had iron from a relatively early date, developing ingenious furnaces to produce the high heat needed for production and to control the amount of air that reached the carbon and iron ore necessary for making iron. Much of Africa moved right into the Iron Age, taking the basic technology and adapting it to local conditions and resources.
The diffusion of agriculture and later of iron was accompanied by a great movement of people who may have carried these innovations. These people probably originated in eastern Nigeria. Their migration may have been set in motion by an increase in population caused by a movement of peoples fleeing the desiccation, or drying up, of the Sahara. They spoke a language, proto-Bantu (“Bantu” means “the people”), which is the parent tongue of a language of a large number of Bantu languages still spoken throughout sub-Sahara Africa. Why and how these people spread out into central and southern Africa remains a mystery, but archaeologists believe that their iron weapons allowed them to conquer their hunting-gathering opponents, who still used stone implements. Still, the process is uncertain, and peaceful migration—or simply rapid demographic growth—may have also caused the Bantu explosion.
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The Rise of TeotihuacánThe city of Teotihuacán, which lay about 50 kilometers northeast of modern-day Mexico City, began its growth by 200-100 B.C. At its height, between about A.D. 150 and 700, it probably had a population of more than 125,000 people and covered at least 20 square kilometers. It had over 2,000 apartment complexes, a great market, a large number of industrial workshops, an administrative center, a number of massive religious edifices, and a regular grid pattern of streets and buildings. Clearly, much planning and central control were involved in the expansion and ordering of this great metropolis. Moreover, the city had economic and perhaps religious contacts with most parts of Mesoamerica (modern Central America and Mexico).
How did this tremendous development take place, and why did it happen in the Teotihuacán Valley? Among the main factors are Teotihuacán’s geographic location on a natural trade route to the south and east of the Valley of Mexico, the obsidian resources in the Teotihuacán Valley itself, and the valley’s potential for extensive irrigation. The exact role of other factors is much more difficult to pinpoint―for instance, Teotihuacán’s religious significance as a shrine, the historical situation in and around the Valley of Mexico toward the end of the first millennium B.C., the ingenuity and foresightedness of Teotihuacán’s elite, and, finally, the impact of natural disasters, such as the volcanic eruptions of the late first millennium B.C.
This last factor is at least circumstantially implicated in Teotihuacán’s rise. Prior to 200 B.C., a number of relatively small centers coexisted in and near the Valley of Mexico. Around this time, the largest of these centers, Cuicuilco, was seriously affected by a volcanic eruption, with much of its agricultural land covered by lava. With Cuicuilco eliminated as a potential rival, any one of a number of relatively modest towns might have emerged as a leading economic and political power in Central Mexico. The archaeological evidence clearly indicates, though, that Teotihuacán was the center that did arise as the predominant force in the area by the first century A.D.
It seems likely that Teotihuacán’s natural resources, along with the city elite’s ability to recognize their potential, gave the city a competitive edge over its neighbors. The valley, like many other places in Mexican and Guatemalan highlands, was rich in obsidian. The hard volcanic stone was a resource that had been in great demand for many years, at least since the rise of the Olmecs (a people who flourished between 1200 and 400 B.C.), and it apparently had a secure market. Moreover, recent research on obsidian tools found at Olmec sites has shown that some of the obsidian obtained by the Olmecs originated near Teotihuacán. Teotihuacán obsidian must have been recognized as a valuable commodity for many centuries before the great city arose.
Long-distance trade in obsidian probably gave the elite residents of Teotihuacán access to a wide variety of exotic good, as well as a relatively prosperous life. Such success may have attracted immigrants to Teotihuacán. In addition, Teotihuacán’s elite may have consciously attempted to attract new inhabitants. It is also probable that as early as 200 B.C. Teotihuacán may have achieved some religious significance and its shrine (or shrines) may have served as an additional population magnet. Finally, the growing population was probably fed by increasing the number and size of irrigated fields.
The picture of Teotihuacán that emerges is a classic picture of positive feedback among obsidian mining and working, trade, population growth, irrigation, and religious tourism. The thriving obsidian operation, for example, would necessitate more miners, additional manufacturers of obsidian tools, and additional traders to carry the goods to new markets. All this led to increased wealth, which in turn would attract more immigrants to Teotihuacán. The growing power of the elite, who controlled the economy, would give them the means to physically coerce people to move to Teotihuacán and serve as additions to the labor force. More irrigation works would have to be built to feed the growing population, and this resulted in more power and wealth for the elite.
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Extinction of the DinosaursPaleozoic Era 334 to 248 million years ago
Mesozoic Era 245 to 65 million years ago
—Triassic Period
—Jurassic Period
—Cretaceous Period
Cenozoic Era 65 million years ago to the present
Paleontologists have argued for a long time that the demise of the dinosaurs was caused by climatic alterations associated with slow changes in the positions of continents and seas resulting from plate tectonics. Off and on throughout the Cretaceous (the last period of the Mesozoic era, during which dinosaurs flourished), large shallow seas covered extensive areas of the continents. Data from diverse sources, including geochemical evidence preserved in seafloor sediments, indicate that the Late Cretaceous climate was milder than today’s. The days were not too hot, nor the nights too cold. The summers were not too warm, nor the winters too frigid. The shallow seas on the continents probably buffered the temperature of the nearby air, keeping it relatively constant.
At the end of the Cretaceous, the geological record shows that these seaways retreated from the continents back into the major ocean basins. No one knows why. Over a period of about 100,000 years, while the seas pulled back, climates around the world became dramatically more extreme: warmer days, cooler nights; hotter summers, colder winters. Perhaps dinosaurs could not tolerate these extreme temperature changes and became extinct.
If true, though, why did cold-blooded animals such as snakes, lizards, turtles, and crocodiles survive the freezing winters and torrid summers? These animals are at the mercy of the climate to maintain a livable body temperature. It’s hard to understand why they would not be affected, whereas dinosaurs were left too crippled to cope, especially if, as some scientists believe, dinosaurs were warm-blooded. Critics also point out that the shallow seaways had retreated from and advanced on the continents numerous times during the Mesozoic, so why did the dinosaurs survive the climatic changes associated with the earlier fluctuations but not with this one? Although initially appealing, the hypothesis of a simple climatic change related to sea levels is insufficient to explain all the data.
Dissatisfaction with conventional explanations for dinosaur extinctions led to a surprising observation that, in turn, has suggested a new hypothesis. Many plants and animals disappear abruptly from the fossil record as one moves from layers of rock documenting the end of the Cretaceous up into rocks representing the beginning of the Cenozoic (the era after the Mesozoic). Between the last layer of Cretaceous rock and the first layer of Cenozoic rock, there is often a thin layer of clay. Scientists felt that they could get an idea of how long the extinctions took by determining how long it took to deposit this one centimeter of clay and they thought they could determine the time it took to deposit the clay by determining the amount of the element iridium (Ir) it contained.
Ir has not been common at Earth’s since the very beginning of the planet’s history. Because it usually exists in a metallic state, it was preferentially incorporated in Earth’s core as the planet cooled and consolidated. Ir is found in high concentrations in some meteorites, in which the solar system’s original chemical composition is preserved. Even today, microscopic meteorites continually bombard Earth, falling on both land and sea. By measuring how many of these meteorites fall to Earth over a given period of time, scientists can estimate how long it might have taken to deposit the observed amount of Ir in the boundary clay. These calculations suggest that a period of about one million years would have been required. However, other reliable evidence suggests that the deposition of the boundary clay could not have taken one million years. So the unusually high concentration of Ir seems to require a special explanation.
In view of these facts, scientists hypothesized that a single large asteroid, about 10 to 15 kilometers across, collided with Earth, and the resulting fallout created the boundary clay. Their calculations show that the impact kicked up a dust cloud that cut off sunlight for several months, inhibiting photosynthesis in plants; decreased surface temperatures on continents to below freezing; caused extreme episodes of acid rain; and significantly raised long-term global temperatures through the greenhouse effect. This disruption of food chain and climate would have eradicated the dinosaurs and other organisms in less than fifty years.
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Running Water on MarsPhotographic evidence suggests that liquid water once existed in great quantity on the surface of Mars. Two types of flow features are seen: runoff channels and outflow channels. Runoff channels are found in the southern highlands. These flow features are extensive systems—sometimes hundreds of kilometers in total length—of interconnecting, twisting channels that seem to merge into larger, wider channels. They bear a strong resemblance to river systems on Earth, and geologists think that they are dried-up beds of long-gone rivers that once carried rainfall on Mars from the mountains down into the valleys. Runoff channels on Mars speak of a time 4 billion years ago (the age of the Martian highlands), when the atmosphere was thicker, the surface warmer, and liquid water widespread.
Outflow channels are probably relics of catastrophic flooding on Mars long ago. They appear only in equatorial regions and generally do not form extensive interconnected networks. Instead, they are probably the paths taken by huge volumes of water draining from the southern highlands into the northern plains. The onrushing water arising from these flash floods likely also formed the odd teardrop-shaped “islands” (resembling the miniature versions seen in the wet sand of our beaches at low tide) that have been found on the plains close to the ends of the outflow channels. Judging from the width and depth of the channels, the flow rates must have been truly enormous—perhaps as much as a hundred times greater than the 105 tons per second carried by the great Amazon river. Flooding shaped the outflow channels approximately 3 billion years ago, about the same times as the northern volcanic plains formed.
Some scientists speculate that Mars may have enjoyed an extended early Period during which rivers, lakes, and perhaps even oceans adorned its surface. A 2003 Mars Global Surveyor image shows what mission specialists think may be a delta—a fan-shaped network of channels and sediments where a river once flowed into a larger body of water, in this case a lake filling a crater in the southern highlands. Other researchers go even further, suggesting that the data provide evidence for large open expenses of water on the early Martian surface. A computer-generated view of the Martian north polar region shows the extent of what may have been an ancient ocean covering much of the northern lowlands. The Hellas Basin, which measures some 3,000 kilometers across and has a floor that lies nearly 9 kilometers below the basin’s rim, is another candidate for an ancient Martian sea.
These ideas remain controversial. Proponents point to features such as the terraced “beaches” shown in one image, which could conceivably have been left behind as a lake or ocean evaporated and the shoreline receded. But detractors maintain that the terraces could also have been created by geological activity, perhaps related to the geologic forces that depressed the Northern Hemisphere far below the level of the south, in which case they have nothing whatever to do with Martian water. Furthermore, Mars Global Surveyor data released in 2003 seem to indicate that the Martian surface contains too few carbonate rock layers—layers containing compounds of carbon and oxygen—that should have been formed in abundance in an ancient ocean. Their absence supports the picture of a cold, dry Mars that never experienced the extended mild period required to form lakes and oceans. However, more recent data imply that at least some parts of the planet did in fact experience long periods in the past during which liquid water existed on the surface.
Aside from some small-scale gullies (channels) found since 2000, which are inconclusive, astronomers have no direct evidence for liquid water anywhere on the surface of Mars today, and the amount of water vapor in the Martian atmosphere is tiny. Yet even setting aside the unproven hints of ancient oceans, the extent of the outflow channels suggests that a huge total volume of water existed on Mars in the past. Where did all the water go? The answer may be that virtually all the water on Mars is now locked in the permafrost layer under the surface, with more contained in the planet’s polar caps.
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Colonizing the Americas via the Northwest CoastIt has long been accepted that the Americas were colonized by a migration of peoples from Asia, slowly traveling across a land bridge called Beringia (now the Bering Strait between northeastern Asia and Alaska) during the last Ice Age. The first water craft theory about this migration was that around 11,000-12,000 years ago there was an ice-free corridor stretching from eastern Beringia to the areas of North America south of the great northern glaciers. It was this midcontinental corridor between two massive ice sheets–the Laurentide to the east and the Cordilleran to the west–that enabled the southward migration. But belief in this ice-free corridor began to crumble when paleoecologist Glen MacDonald demonstrated that some of the most important radiocarbon dates used to support the existence of an ice-free corridor were incorrect. He persuasively argued that such an ice-free corridor did not exist until much later, when the continental ice began its final retreat.
Support is growing for the alternative theory that people using watercraft, possibly skin boats, moved southward from Beringia along the Gulf of Alaska and then southward along the Northwest coast of North America possibly as early as 16,000 years ago. This route would have enabled humans to enter southern areas of the Americas prior to the melting of the continental glaciers. Until the early 1970s,most archaeologists did not consider the coast a possible migration route into the Americas because geologists originally believed that during the last Ice Age the entire Northwest Coast was covered by glacial ice. It had been assumed that the ice extended westward from the Alaskan/Canadian mountains to the very edge of the continental shelf, the flat, submerged part of the continent that extends into the ocean. This would have created a barrier of ice extending from the Alaska Peninsula, through the Gulf of Alaska and southward along the Northwest Coast of north America to what is today the state of Washington.
The most influential proponent of the coastal migration route has been Canadian archaeologist Knut Fladmark. He theorized that with the use of watercraft, people gradually colonized unglaciated refuges and areas along the continental shelf exposed by the lower sea level. Fladmark’s hypothesis received additional support form from the fact that the greatest diversity in native American languages occurs along the west coast of the Americas, suggesting that this region has been settled the longest.
More recent geologic studies documented deglaciation and the existence of ice-free areas throughout major coastal areas of British Columbia, Canada, by 13,000 years ago. Research now indicates that sizable areas of southeastern Alaska along the inner continental shelf were not covered by ice toward the end of the last Ice Age. One study suggests that except for a 250-mile coastal area between southwestern British Columbia and Washington State, the Northwest Coast of North America was largely free of ice by approximately 16,000 years ago. Vast areas along the coast may have been deglaciated beginning around 16,000 years ago, possibly providing a coastal corridor for the movement of plants, animals, and humans sometime between 13,000 and 14,000 years ago.
The coastal hypothesis has gained increasing support in recent years because the remains of large land animals, such as caribou and brown bears, have been found in southeastern Alaska dating between 10,000 and 12,500 years ago. This is the time period in which most scientists formerly believed the area to be inhospitable for humans. It has been suggested that if the environment were capable of supporting breeding populations of bears, there would have been enough food resources to support humans. Fladmark and other believe that the first human colonization of America occurred by boat along the Northwest Coast during the very late Ice Age, possibly as early as 14,000 years ago. The most recent geologic evidence indicates that it may have been possible for people to colonize ice-free regions along the continental shelf that were still exposed by the lower sea level between13,000 and 14,000 years ago.
The coastal hypothesis suggests an economy based on marine mammal hunting, saltwater fishing, shellfish gathering, and the use of watercraft. Because of the barrier of ice to the east, the Pacific Ocean to the west, and populated areas to the north, there may have been a greater impetus for people to move in a southerly direction.
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Reflection in TeachingTeachers, it is thought, benefit from the practice of reflection, the conscious act of thinking deeply about and carefully examining the interactions and events within their own classrooms. Educators T. Wildman and J. Niles (1987) describe a scheme for developing reflective practice in experienced teachers. This was justified by the view that reflective practice could help teachers to feel more intellectually involved in their role and work in teaching and enable them to cope with the paucity of scientific fact and the uncertainty of knowledge in the discipline of teaching.
Wildman and Niles were particularly interested in investigating the conditions under which reflection might flourish–a subject on which there is little guidance in the literature. They designed an experimental strategy for a group of teachers in Virginia and worked with 40 practicing teachers over several years. They were concerned that many would be “drawn to these new, refreshing” conceptions of teaching only to find that the void between the abstractions and the realities of teacher reflection is too great to bridge. Reflection on a complex task such as teaching is not easy.” The teachers were taken through a program of talking about teaching events, moving on to reflecting about specific issues in a supported, and later an independent, manner.
Wildman and Niles observed that systematic reflection on teaching required a sound ability to understand classroom events in an objective manner. They describe the initial understanding in the teachers with whom they were working as being “utilitarian … and not rich or detailed enough to drive systematic reflection.” Teachers rarely have the time or opportunities to view their own or the teaching of others in an objective manner. Further observation revealed the tendency of teachers to evaluate events rather than review the contributory factors in a considered manner by, in effect, standing outside the situation.
Helping this group of teachers to revise their thinking about classroom events became central. This process took time and patience and effective trainers. The researchers estimate that the initial training of the teachers to view events objectively took between 20 and 30 hours, with the same number of hours again being required to practice the skills of reflection.
Wildman and Niles identify three principles that facilitate reflective practice in a teaching situation. The first is support from administrators in an education system, enabling teachers to understand the requirements of reflective practice and how it relates to teaching students. The second is the availability of sufficient time and space. The teachers in the program described how they found it difficult to put aside the immediate demands of others in order to give themselves the time they needed to develop their reflective skills. The third is the development of a collaborative environment with support from other teachers. Support and encouragement were also required to help teachers in the program cope with aspects of their professional life with which they were not comfortable. Wildman and Niles make a summary comment: “Perhaps the most important thing we learned is the idea of the teacher-as-reflective-practitioner will not happen simply because it is a good or even compelling idea.”
The work of Wildman and Niles suggests the importance of recognizing some of the difficulties of instituting reflective practice. Others have noted this, making a similar point about the teaching profession’s cultural inhibitions about reflective practice. Zeichner and Liston (1987) point out the inconsistency between the role of the teacher as a (reflective) professional decision maker and the more usual role of the teacher as a technician, putting into practice the ideas of theirs. More basic than the cultural issues is the matter of motivation. Becoming a reflective practitioner requires extra work (Jaworski, 1993) and has only vaguely defined goals with, perhaps, little initially perceivable reward and the threat of vulnerability. Few have directly questioned what might lead a teacher to want to become reflective. Apparently, the most obvious reason for teachers to work toward reflective practice is that teacher educators think it is a good thing. There appear to be many unexplored matters about the motivation to reflect – for example, the value of externally motivated reflection as opposed to that of teachers who might reflect by habit.
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The Arrival of Plant Life in HawaiiWhen the Hawaiian Islands emerged from the sea as volcanoes, starting about five million years ago, they were far removed from other landmasses. Then, as blazing sunshine alternated with drenching rains, the harsh, barren surfaces of the black rocks slowly began to soften. Winds brought a variety of life-forms.
Spores light enough to float on the breezes were carried thousands of miles from more ancient lands and deposited at random across the bare mountain flanks. A few of these spores found a toehold on the dark, forbidding rocks and grew and began to work their transformation upon the land. Lichens were probably the first successful flora. These are not single individual plants; each one is a symbiotic combination of an alga and a fungus. The algae capture the sun's energy by photosynthesis and store it in organic molecules. The fungi absorb moisture and mineral salts from the rocks, passing these on in waste products that nourish algae. It is significant that the earliest living things that built communities on these islands are examples of symbiosis, a phenomenon that depends upon the close cooperation of two or more forms of life and a principle that is very important in island communities.
Lichens helped to speed the decomposition of the hard rock surfaces, preparing a soft bed of soil that was abundantly supplied with minerals that had been carried in the molten rock from the bowels of Earth. Now, other forms of life could take hold: ferns and mosses (two of the most ancient types of land plants) that flourish even in rock crevices. These plants propagate by producing spores–tiny fertilized cells that contain all the instructions for making a new plant–but the spore are unprotected by any outer coating and carry no supply of nutrient. Vast numbers of them fall on the ground beneath the mother plants. Sometimes they are carried farther afield by water or by wind. But only those few spores that settle down in very favorable locations can start new life; the vast majority fall on barren ground. By force of sheer numbers, however, the mosses and ferns reached Hawaii, survived, and multiplied. Some species developed great size, becoming tree ferns that even now grow in the Hawaiian forests.
Many millions of years after ferns evolved (but long before the Hawaiian Islands were born from the sea), another kind of flora evolved on Earth: the seed-bearing plants. This was a wonderful biological invention. The seed has an outer coating that surrounds the genetic material of the new plant, and inside this covering is a concentrated supply of nutrients. Thus the seed’s chances of survival are greatly enhanced over those of the naked spore. One type of seed-bearing plant, the angiosperm, includes all forms of blooming vegetation. In the angiosperm the seeds are wrapped in an additional layer of covering. Some of these coats are hard–like the shell of a nut–for extra protection. Some are soft and tempting, like a peach or a cherry. In some angiosperms the seeds are equipped with gossamer wings, like the dandelion and milkweed seeds. These new characteristics offered better ways for the seed to move to new habitats. They could travel through the air, float in water, and lie dormant for many months.
Plants with large, buoyant seeds—like coconuts—drift on ocean currents and are washed up on the shores. Remarkably resistant to the vicissitudes of ocean travel, they can survive prolonged immersion in saltwater when they come to rest on warm beaches and the conditions are favorable, the seed coats soften. Nourished by their imported supply of nutrients, the young plants push out their roots and establish their place in the sun.
By means of these seeds, plants spread more widely to new locations, even to isolated islands like the Hawaiian archipelago, which lies more than 2,000 miles west of California and 3,500 miles east of Japan. The seeds of grasses, flowers, and blooming trees made the long trips to these islands. (Grasses are simple forms of angiosperms that bear their encapsulated seeds on long stalks.) In a surprisingly short time, angiosperms filled many of the land areas on Hawaii that had been bare.
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Chinese PotteryChina has one of the world's oldest continuous civilizations—despite invasions and occasional foreign rule. A country as vast as China with so long-lasting a civilization has a complex social and visual history, within which pottery and porcelain play a major role.
The function and status of ceramics in China varied from dynasty to dynasty, so they may be utilitarian, burial, trade-collectors', or even ritual objects, according to their quality and the era in which they were made. The ceramics fall into three broad types—earthenware, stoneware, and porcelain—for vessels, architectural items such as roof tiles, and modeled objects and figures. In addition, there was an important group of sculptures made for religious use, the majority of which were produced in earthenware.
The earliest ceramics were fired to earthenware temperatures, but as early as the fifteenth century B.C., high-temperature stonewares were being made with glazed surfaces. During the Six Dynasties period (AD 265-589), kilns in north China were producing high-fired ceramics of good quality. Whitewares produced in Hebei and Henan provinces from the seventh to the tenth centuries evolved into the highly prized porcelains of the Song dynasty (AD. 960-1279), long regarded as one of the high points in the history of China's ceramic industry. The tradition of religious sculpture extends over most historical periods but is less clearly delineated than that of stonewares or porcelains, for it embraces the old custom of earthenware burial ceramics with later religious images and architectural ornament. Ceramic products also include lead-glazed tomb models of the Han dynasty, three-color lead-glazed vessels and figures of the Tang dynasty, and Ming three-color temple ornaments, in which the motifs were outlined in a raised trail of slip—as well as the many burial ceramics produced in imitation of vessels made in materials of higher intrinsic value.
Trade between the West and the settled and prosperous Chinese dynasties introduced new forms and different technologies. One of the most far-reaching examples is the impact of the fine ninth-century AD. Chinese porcelain wares imported into the Arab world. So admired were these pieces that they encouraged the development of earthenware made in imitation of porcelain and instigated research into the method of their manufacture. From the Middle East the Chinese acquired a blue pigment—a purified form of cobalt oxide unobtainable at that time in China—that contained only a low level of manganese. Cobalt ores found in China have a high manganese content, which produces a more muted blue-gray color. In the seventeenth century, the trading activities of the Dutch East India Company resulted in vast quantities of decorated Chinese porcelain being brought to Europe, which stimulated and influenced the work of a wide variety of wares, notably Delft. The Chinese themselves adapted many specific vessel forms from the West, such as bottles with long spouts, and designed a range of decorative patterns especially for the European market.
Just as painted designs on Greek pots may seem today to be purely decorative, whereas in fact they were carefully and precisely worked out so that at the time, their meaning was clear, so it is with Chinese pots. To twentieth-century eyes, Chinese pottery may appear merely decorative, yet to the Chinese the form of each object and its adornment had meaning and significance. The dragon represented the emperor, and the phoenix, the empress; the pomegranate indicated fertility, and a pair of fish, happiness; mandarin ducks stood for wedded bliss; the pine tree, peach, and crane are emblems of long life; and fish leaping from waves indicated success in the civil service examinations. Only when European decorative themes were introduced did these meanings become obscured or even lost.
From early times pots were used in both religious and secular contexts. The imperial court commissioned work and in the Yuan dynasty (A.D. 1279-1368) an imperial ceramic factory was established at Jingdezhen. Pots played an important part in some religious ceremonies. Long and often lyrical descriptions of the different types of ware exist that assist in classifying pots, although these sometimes confuse an already large and complicated picture.
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Variations in the ClimateOne of the most difficult aspects of deciding whether current climatic events reveal evidence of the impact of human activities is that it is hard to get a measure of what constitutes the natural variability of the climate. We know that over the past millennia the climate has undergone major changes without any significant human intervention. We also know that the global climate system is immensely complicated and that everything is in some way connected, and so the system is capable of fluctuating in unexpected ways. We need therefore to know how much the climate can vary of its own accord in order to interpret with confidence the extent to which recent changes are natural as opposed to being the result of human activities.
Instrumental records do not go back far enough to provide us with reliable measurements of global climatic variability on timescales longer than a century. What we do know is that as we include longer time intervals, the record shows increasing evidence of slow swings in climate between different regimes. To build up a better picture of fluctuations appreciably further back in time requires us to use proxy records.
Over long periods of time, substances whose physical and chemical properties change with the ambient climate at the time can be deposited in a systematic way to provide a continuous record of changes in those properties overtime, sometimes for hundreds or thousands of years. Generally, the layering occurs on an annual basis, hence the observed changes in the records can be dated. Information on temperature, rainfall, and other aspects of the climate that can be inferred from the systematic changes in properties is usually referred to as proxy data. Proxy temperature records have been reconstructed from ice core drilled out of the central Greenland ice cap, calcite shells embedded in layered lake sediments in Western Europe, ocean floor sediment cores from the tropical Atlantic Ocean, ice cores from Peruvian glaciers, and ice cores from eastern Antarctica. While these records provide broadly consistent indications that temperature variations can occur on a global scale, there are nonetheless some intriguing differences, which suggest that the pattern of temperature variations in regional climates can also differ significantly from each other.
What the proxy records make abundantly clear is that there have been significant natural changes in the climate over timescales longer than a few thousand years. Equally striking, however, is the relative stability of the climate in the past 10,000 years (the Holocene period).
To the extent that the coverage of the global climate from these records can provide a measure of its true variability, it should at least indicate how all the natural causes of climate change have combined. These include the chaotic fluctuations of the atmosphere, the slower but equally erratic behavior of the oceans, changes in the land surfaces, and the extent of ice and snow. Also included will be any variations that have arisen from volcanic activity, solar activity, and, possibly, human activities.
One way to estimate how all the various processes leading to climate variability will combine is by using computer models of the global climate. They can do only so much to represent the full complexity of the global climate and hence may give only limited information about natural variability. Studies suggest that to date the variability in computer simulations is considerably smaller than in data obtained from the proxy records.
In addition to the internal variability of the global climate system itself, there is the added factor of external influences, such as volcanoes and solar activity. There is a growing body of opinion that both these physical variations have a measurable impact on the climate. Thus we need to be able to include these in our deliberations. Some current analyses conclude that volcanoes and solar activity explain quite a considerable amount of the observed variability in the period from the seventeenth to the early twentieth centuries, but that they cannot be invoked to explain the rapid warming in recent decades.
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Seventeenth - Century European Economic GrowthIn the late sixteenth century and into the seventeenth, Europe continued the growth that had lifted it out of the relatively less prosperous medieval period (from the mid 400s to the late 1400s). Among the key factors behind this growth were increased agricultural productivity and an expansion of trade.
Populations cannot grow unless the rural economy can produce enough additional food to feed more people. During the sixteenth century, farmers brought more land into cultivation at the expense of forests and fens (low-lying wetlands). Dutch land reclamation in the Netherlands in the sixteenth and seventeenth centuries provides the most spectacular example of the expansion of farmland: the Dutch reclaimed more than 36,000 acres from 1590 to 1615 alone.
Much of the potential for European economic development lay in what at first glance would seem to have been only sleepy villages. Such villages, however, generally lay in regions of relatively advanced agricultural production, permitting not only the survival of peasants but also the accumulation of an agricultural surplus for investment. They had access to urban merchants, markets, and trade routes.
Increased agricultural production in turn facilitated rural industry, an intrinsic part of the expansion of industry. Woolens and textile manufacturers, in particular, utilized rural cottage (in-home) production, which took advantage of cheap and plentiful rural labor. In the German states, the ravages of the Thirty Years' War (1618-1648) further moved textile production into the countryside. Members of poor peasant families spun or wove cloth and linens at home for scant remuneration in an attempt to supplement meager family income.
More extended trading networks also helped develop Europe's economy in this period. English and Dutch ships carrying rye from the Baltic states reached Spain and Portugal. Population growth generated an expansion of small-scale manufacturing, particularly of handicrafts, textiles, and metal production in England, Flanders, parts of northern Italy, the southwestern German states, and parts of Spain. Only iron smelting and mining required marshaling a significant amount of capital (wealth invested to create more wealth).
The development of banking and other financial services contributed to the expansion of trade. By the middle of the sixteenth century, financiers and traders commonly accepted bills of exchange in place of gold or silver for other goods. Bills of exchange, which had their origins in medieval Italy, were promissory notes (written promises to pay a specified amount of money by a certain date) that could be sold to third parties. In this way, they provided credit. At mid-century, an Antwerp financier only slightly exaggerated when he claimed, “One can no more trade without bills of exchange than sail without water." Merchants no longer had to carry gold and silver over long, dangerous journeys. An Amsterdam merchant purchasing soap from a merchant in Marseille could go to an exchanger and pay the exchanger the equivalent sum in guilders, the Dutch currency. The exchanger would then send a bill of exchange to a colleague in Marseille, authorizing the colleague to pay the Marseille merchant in the merchant's own currency after the actual exchange of goods had taken place.
Bills of exchange contributed to the development of banks, as exchangers began to provide loans. Not until the eighteenth century, however, did such banks as the Bank of Amsterdam and the Bank of England begin to provide capital for business investment. Their principal function was to provide funds for the state.
The rapid expansion in international trade also benefitted from an infusion of capital, stemming largely from gold and silver brought by Spanish vessels from the Americas. This capital financed the production of goods, storage, trade, and even credit across Europe and overseas. Moreover an increased credit supply was generated by investments and loans by bankers and wealthy merchants to states and by joint-stock partnerships—an English innovation (the first major company began in 1600). Unlike short-term financial cooperation between investors for a single commercial undertaking, joint-stock companies provided permanent funding of capital by drawing on the investments of merchants and other investors who purchased shares in the company.
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Ancient Egyptian SculptureIn order to understand ancient Egyptian art, it is vital to know as much as possible of the elite Egyptians' view of the world and the functions and contexts of the art produced for them. Without this knowledge we can appreciate only the formal content of Egyptian art, and we will fail to understand why it was produced or the concepts that shaped it and caused it to adopt its distinctive forms. In fact, a lack of understanding concerning the purposes of Egyptian art has often led it to be compared unfavorably with the art of other cultures: Why did the Egyptians not develop sculpture in which the body turned and twisted through space like classical Greek statuary? Why do the artists seem to get left and right confused? And why did they not discover the geometric perspective as European artists did in the Renaissance? The answer to such questions has nothing to do with a lack of skill or imagination on the part of Egyptian artists and everything to do with the purposes for which they were producing their art.
The majority of three-dimensional representations, whether standing, seated, or kneeling, exhibit what is called frontality: they face straight ahead, neither twisting nor turning. When such statues are viewed in isolation, out of their original context and without knowledge of their function, it is easy to criticize them for their rigid attitudes that remained unchanged for three thousand years. Frontality is, however, directly related to the functions of Egyptian statuary and the contexts in which the statues were set up. Statues were created not for their decorative effect but to play a primary role in the cults of the gods, the king, and the dead. They were designed to be put in places where these beings could manifest themselves in order to be the recipients of ritual actions. Thus it made sense to show the statue looking ahead at what was happening in front of it, so that the living performer of the ritual could interact with the divine or deceased recipient. Very often such statues were enclosed in rectangular shrines or wall niches whose only opening was at the front, making it natural for the statue to display frontality. Other statues were designed to be placed within an architectural setting, for instance, in front of the monumental entrance gateways to temples known as pylons, or in pillared courts, where they would be placed against or between pillars: their frontality worked perfectly within the architectural context.
Statues were normally made of stone, wood, or metal. Stone statues were worked from single rectangular blocks of material and retained the compactness of the original shape. The stone between the arms and the body and between the legs in standing figures or the legs and the seat in seated ones was not normally cut away. From a practical aspect this protected the figures against breakage and psychologically gives the images a sense of strength and power, usually enhanced by a supporting back pillar. By contrast, wooden statues were carved from several pieces of wood that were pegged together to form the finished work, and metal statues were either made by wrapping sheet metal around a wooden core or cast by the lost wax process. The arms could be held away from the body and carry separate items in their hands; there is no back pillar. The effect is altogether lighter and freer than that achieved in stone, but because both perform the same function, formal wooden and metal statues still display frontality.
Apart from statues representing deities, kings, and named members of the elite that can be called formal, there is another group of three-dimensional representations that depicts generic figures, frequently servants, from the nonelite population. The function of these is quite different. Many are made to be put in the tombs of the elite in order to serve the tomb owners in the afterlife. Unlike formal statues that are limited to static poses of standing, sitting, and kneeling, these figures depict a wide range of actions, such as grinding grain, baking bread, producing pots, and making music, and they are shown in appropriate poses, bending and squatting as they carry out their tasks.
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Orientation and NavigationTo South Americans, robins are birds that fly north every spring. To North Americans, the robins simply vacation in the south each winter. Furthermore, they fly to very specific places in South America and will often come back to the same trees in North American yards the following spring. The question is not why they would leave the cold of winter so much as how they find their way around. The question perplexed people for years, until, in the 1950s, a German scientist named Gustave Kramer provided some answers and, in the process, raised new questions.
Kramer initiated important new kinds of research regarding how animals orient and navigate. Orientation is simply facing in the right direction; navigation involves finding ones way from point A to point B.
Early in his research, Kramer found that caged migratory birds became very restless at about the time they would normally have begun migration in the wild. Furthermore, he noticed that as they fluttered around in the cage, they often launched themselves in the direction of their normal migratory route. He then set up experiments with caged starlings and found that their orientation was, in fact, in the proper migratory direction except when the sky was overcast, at which times there was no clear direction to their restless movements. Kramer surmised, therefore, that they were orienting according to the position of the Sun. To test this idea, he blocked their view of the Sun and used mirrors to change its apparent position. He found that under these circumstances, the birds oriented with respect to the new "Sun." They seemed to be using the Sun as a compass to determine direction. At the time, this idea seemed preposterous. How could a bird navigate by the Sun when some of us lose our way with road maps? Obviously, more testing was in order.
So, in another set of experiments, Kramer put identical food boxes around the cage, with food in only one of the boxes. The boxes were stationary, and the one containing food was always at the same point of the compass. However, its position with respect to the surroundings could be changed by revolving either the inner cage containing the birds or the outer walls, which served as the background. As long as the birds could see the Sun, no matter how their surroundings were altered, they went directly to the correct food box. Whether the box appeared in front of the right wall or the left wall, they showed no signs of confusion. On overcast days, however, the birds were disoriented and had trouble locating their food box.
In experimenting with artificial suns, Kramer made another interesting discovery. If the artificial Sun remained stationary, the birds would shift their direction with respect to it at a rate of about 15 degrees per hour, the Sun's rate of movement across the sky. Apparently, the birds were assuming that the "Sun" they saw was moving at that rate. When the real Sun was visible, however, the birds maintained a constant direction as it moved across the sky. In other words, they were able to compensate for the Sun's movement. This meant that some sort of biological clock was operating-and a very precise clock at that.
What about birds that migrate at night? Perhaps they navigate by the night sky. To test the idea, caged night-migrating birds were placed on the floor of a planetarium during their migratory period. A planetarium is essentially a theater with a domelike ceiling onto which a night sky can be projected for any night of the year. When the planetarium sky matched the sky outside, the birds fluttered in the direction of their normal migration. But when the dome was rotated, the birds changed their direction to match the artificial sky. The results clearly indicated that the birds were orienting according to the stars.
There is accumulating evidence indicating that birds navigate by using a wide variety of environmental cues. Other areas under investigation include magnetism, landmarks, coastlines, sonar, and even smells. The studies are complicated by the fact that the data are sometimes contradictory and the mechanisms apparently change from time to time. Furthermore, one sensory ability may back up another.
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Begging by NestlingsMany signals that animals make seem to impose on the signalers costs that are overly damaging. A classic example is noisy begging by nestling songbirds when a parent returns to the nest with food. These loud cheeps and peeps might give the location of the nest away to a listening hawk or raccoon, resulting in the death of the defenseless nestlings. In fact, when tapes of begging tree swallows were played at an artificial swallow nest containing an egg, the egg in that “noisy” nest was taken or destroyed by predators before the egg in a nearby quiet nest in 29 of 37 trials.
Further evidence for the costs of begging comes from a study of differences in the begging calls of warbler species that nest on the ground versus those that nest in the relative safety of trees. The young of ground-nesting warblers produce begging cheeps of higher frequencies than do their tree-nesting relatives. These higher-frequency sounds do not travel as far, and so may better conceal the individuals producing them, who are especially vulnerable to predators in their ground nests. David Haskell created artificial nests with clay eggs and placed them on the ground beside a tape recorder that played the begging calls of either tree-nesting or of ground-nesting warblers. The eggs “advertised” by the tree-nesters' begging calls were found bitten significantly more often than the eggs associated with the ground-nesters' calls.
The hypothesis that begging calls have evolved properties that reduce their potential for attracting predators yields a prediction: baby birds of species that experience high rates of nest predation should produce softer begging signals of higher frequency than nestlings of other species less often victimized by nest predators. This prediction was supported by data collected in one survey of 24 species from an Arizona forest, more evidence that predator pressure favors the evolution of begging calls that are hard to detect and pinpoint.
Given that predators can make it costly to beg for food, what benefit do begging nestlings derive from their communications? One possibility is that a noisy baby bird provides accurate signals of its real hunger and good health, making it worthwhile for the listening parent to give it food in a nest where several other offspring are usually available to be fed. If this hypothesis is true, then it follows that nestlings should adjust the intensity of their signals in relation to the signals produced by their nestmates, who are competing for parental attention. When experimentally deprived baby robins are placed in a nest with normally fed siblings, the hungry nestlings beg more loudly than usual—but so do their better-fed siblings, though not as loudly as the hungrier birds.
If parent birds use begging intensity to direct food to healthy offspring capable of vigorous begging, then parents should make food delivery decisions on the basis of their offsprings’ calls. Indeed, if you take baby tree swallows out of a nest for an hour feeding half the set and starving the other half, when the birds are replaced in the nest, the starved youngsters beg more loudly than the fed birds, and the parent birds feed the active beggars more than those who beg less vigorously.
As these experiments show, begging apparently provides a signal of need that parents use to make judgments about which offspring can benefit most from a feeding. But the question arises, why don't nestlings beg loudly when they aren't all that hungry? By doing so, they could possibly secure more food, which should result in more rapid growth or larger size, either of which is advantageous. The answer lies apparently not in the increased energy costs of exaggerated begging—such energy costs are small relative to the potential gain in calories—but rather in the damage that any successful cheater would do to its siblings, which share genes with one another. An individual's success in propagating his or her genes can be affected by more than just his or her own personal reproductive success. Because close relatives have many of the same genes, animals that harm their close relatives may in effect be destroying some of their own genes. Therefore, a begging nestling that secures food at the expense of its siblings might actually leave behind fewer copies of its genes overall than it might otherwise.
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Which Hand Did They UseWe all know that many more people today are right-handed than left-handed. Can one trace this same pattern far back in prehistory? Much of the evidence about right-hand versus left-hand dominance comes from stencils and prints found in rock shelters in Australia and elsewhere, and in many Ice Age caves in France, Spain, and Tasmania. When a left hand has been stenciled, this implies that the artist was right-handed, and vice versa. Even though the paint was often sprayed on by mouth, one can assume that the dominant hand assisted in the operation. One also has to make the assumption that hands were stenciled palm downward—a left hand stenciled palm upward might of course look as if it were a right hand. Of 158 stencils in the French cave of Gargas, 136 have been identified as left, and only 22 as right; right-handedness was therefore heavily predominant.
Cave art furnishes other types of evidence of this phenomenon. Most engravings, for example, are best lit from the left, as befits the work of right-handed artists, who generally prefer to have the light source on the left so that the shadow of their hand does not fall on the tip of the engraving tool or brush. In the few cases where an Ice Age figure is depicted holding something, it is mostly, though not always, in the right hand.
Clues to right-handedness can also be found by other methods. Right-handers tend to have longer, stronger, and more muscular bones on the right side, and Marcellin Boule as long ago as 1911 noted the La Chapelle-aux-Saints Neanderthal skeleton had a right upper arm bone that was noticeably stronger than the left. Similar observations have been made on other Neanderthal skeletons such as La Ferrassie I and Neanderthal itself.
Fractures and other cut marks are another source of evidence. Right-handed soldiers tend to be wounded on the left. The skeleton of a 40- or 50-year-old Nabatean warrior, buried 2,000 years ago in the Negev Desert, Israel, had multiple healed fractures to the skull, the left arm, and the ribs.
Tools themselves can be revealing. Long-handed Neolithic spoons of yew wood preserved in Alpine villages dating to 3000 B.C. have survived; the signs of rubbing on their left side indicate that their users were right-handed. The late Ice Age rope found in the French cave of Lascaux consists of fibers spiraling to the right, and was therefore tressed by a righthander.
Occasionally one can determine whether stone tools were used in the right hand or the left, and it is even possible to assess how far back this feature can be traced. In stone toolmaking experiments, Nick Toth, a right-hander, held the core (the stone that would become the tool) in his left hand and the hammer stone in his right. As the tool was made, the core was rotated clockwise, and the flakes, removed in sequence, had a little crescent of cortex (the core's outer surface) on the side. Toth's knapping produced 56 percent flakes with the cortex on the right, and 44 percent left-oriented flakes. A left-handed toolmaker would produce the opposite pattern. Toth has applied these criteria to the similarly made pebble tools from a number of early sites (before 1.5 million years) at Koobi Fora, Kenya, probably made by Homo habilis. At seven sites he found that 57 percent of the flakes were right-oriented, and 43 percent left, a pattern almost identical to that produced today.
About 90 percent of modern humans are right-handed: we are the only mammal with a preferential use of one hand. The part of the brain responsible for fine control and movement is located in the left cerebral hemisphere, and the findings above suggest that the human brain was already asymmetrical in its structure and function not long after 2 million years ago. Among Neanderthalers of 70,000–35,000 years ago, Marcellin Boule noted that the La Chapelle-aux-Saints individual had a left hemisphere slightly bigger than the right, and the same was found for brains of specimens from Neanderthal, Gibraltar, and La Quina.
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Transition to Sound in FilmThe shift from silent to sound film at the end of the 1920s marks, so far, the most important transformation in motion picture history. Despite all the highly visible technological developments in theatrical and home delivery of the moving image that have occurred over the decades since then, no single innovation has come close to being regarded as a similar kind of watershed. In nearly every language, however the words are phrased, the most basic division in cinema history lies between films that are mute and films that speak.
Yet this most fundamental standard of historical periodization conceals a host of paradoxes. Nearly every movie theater, however modest, had a piano or organ to provide musical accompaniment to silent pictures. In many instances, spectators in the era before recorded sound experienced elaborate aural presentations alongside movies' visual images, from the Japanese benshi (narrators) crafting multivoiced dialogue narratives to original musical compositions performed by symphony-size orchestras in Europe and the United States. In Berlin, for the premiere performance outside the Soviet Union of The Battleship Potemkin, film director Sergei Eisenstein worked with Austrian composer Edmund Meisel (1874-1930) on a musical score matching sound to image; the Berlin screenings with live music helped to bring the film its wide international fame.
Beyond that, the triumph of recorded sound has overshadowed the rich diversity of technological and aesthetic experiments with the visual image that were going forward simultaneously in the 1920s. New color processes, larger or differently shaped screen sizes, multiple-screen projections, even television, were among the developments invented or tried out during the period, sometimes with startling success. The high costs of converting to sound and the early limitations of sound technology were among the factors that suppressed innovations or retarded advancement in these other areas. The introduction of new screen formats was put off for a quarter century, and color, though utilized over the next two decades for special productions, also did not become a norm until the 1950s.
Though it may be difficult to imagine from a later perspective, a strain of critical opinion in the 1920s predicted that sound film would be a technical novelty that would soon fade from sight, just as had many previous attempts, dating well back before the First World War, to link images with recorded sound. These critics were making a common assumption—that the technological inadequacies of earlier efforts (poor synchronization, weak sound amplification, fragile sound recordings) would invariably occur again. To be sure, their evaluation of the technical flaws in 1920s sound experiments was not so far off the mark, yet they neglected to take into account important new forces in the motion picture field that, in a sense, would not take no for an answer.
These forces were the rapidly expanding electronics and telecommunications companies that were developing and linking telephone and wireless technologies in the 1920s. In the United States, they included such firms as American Telephone and Telegraph, General Electric, and Westinghouse. They were interested in all forms of sound technology and all potential avenues for commercial exploitation. Their competition and collaboration were creating the broadcasting industry in the United States, beginning with the introduction of commercial radio programming in the early 1920s. With financial assets considerably greater than those in the motion picture industry, and perhaps a wider vision of the relationships among entertainment and communications media, they revitalized research into recording sound for motion pictures.
In 1929 the United States motion picture industry released more than 300 sound films—a rough figure, since a number were silent films with music tracks, or films prepared in dual versions, to take account of the many cinemas not yet wired for sound. At the production level, in the United States the conversion was virtually complete by 1930. In Europe it took a little longer, mainly because there were more small producers for whom the costs of sound were prohibitive, and in other parts of the world problems with rights or access to equipment delayed the shift to sound production for a few more years (though cinemas in major cities may have been wired in order to play foreign sound films). The triumph of sound cinema was swift, complete, and enormously popular.
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Water in the DesertRainfall is not completely absent in desert areas, but it is highly variable. An annual rainfall of four inches is often used to define the limits of a desert. The impact of rainfall upon the surface water and groundwater resources of the desert is greatly influenced by landforms. Flats and depressions where water can collect are common features, but they make up only a small part of the landscape.
Arid lands, surprisingly, contain some of the world’s largest river systems, such as the Murray-Darling in Australia, the Rio Grande in North America, the Indus in Asia, and the Nile in Africa. These rivers and river systems are known as "exogenous" because their sources lie outside the arid zone. They are vital for sustaining life in some of the driest parts of the world. For centuries, the annual floods of the Nile, Tigris, and Euphrates, for example, have brought fertile silts and water to the inhabitants of their lower valleys. Today, river discharges are increasingly controlled by human intervention, creating a need for international river-basin agreements. The filling of the Ataturk and other dams in Turkey has drastically reduced flows in the Euphrates, with potentially serious consequences for Syria and Iraq.
The flow of exogenous rivers varies with the season. The desert sections of long rivers respond several months after rain has fallen outside the desert, so that peak flows may be in the dry season. This is useful for irrigation, but the high temperatures, low humidities, and different day lengths of the dry season, compared to the normal growing season, can present difficulties with some crops.
Regularly flowing rivers and streams that originate within arid lands are known as "endogenous." These are generally fed by groundwater springs, and many issue from limestone massifs, such as the Atlas Mountains in Morocco. Basaltic rocks also support springs, notably at the Jabal Al-Arab on the Jordan-Syria border. Endogenous rivers often do not reach the sea but drain into inland basins, where the water evaporates or is lost in the ground. Most desert streambeds are normally dry, but they occasionally receive large flows of water and sediment.
Deserts contain large amounts of groundwater when compared to the amounts they hold in surface stores such as lakes and rivers. But only a small fraction of groundwater enters the hydrological cycle—feeding the flows of streams, maintaining lake levels, and being recharged (or refilled) through surface flows and rainwater. In recent years, groundwater has become an increasingly important source of freshwater for desert dwellers. The United Nations Environment Programme and the World Bank have funded attempts to survey the groundwater resources of arid lands and to develop appropriate extraction techniques. Such programs are much needed because in many arid lands there is only a vague idea of the extent of groundwater resources. It is known, however, that the distribution of groundwater is uneven, and that much of it lies at great depths.
Groundwater is stored in the pore spaces and joints of rocks and unconsolidated (unsolidified) sediments or in the openings widened through fractures and weathering. The water-saturated rock or sediment is known as an "aquifer". Because they are porous, sedimentary rocks, such as sandstones and conglomerates, are important potential sources of groundwater. Large quantities of water may also be stored in limestones when joints and cracks have been enlarged to form cavities. Most limestone and sandstone aquifers are deep and extensive but may contain groundwaters that are not being recharged. Most shallow aquifers in sand and gravel deposits produce lower yields, but they can be rapidly recharged. Some deep aquifers are known as "fossil waters. The term "fossil" describes water that has been present for several thousand years. These aquifers became saturated more than 10,000 years ago and are no longer being recharged.
Water does not remain immobile in an aquifer but can seep out at springs or leak into other aquifers. The rate of movement may be very slow: in the Indus plain, the movement of saline (salty) groundwaters has still not reached equilibrium after 70 years of being tapped. The mineral content of groundwater normally increases with the depth, but even quite shallow aquifers can be highly saline.
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Types of Social GroupsLife places us in a complex web of relationships with other people. Our humanness arises out of these relationships in the course of social interaction. Moreover, our humanness must be sustained through social interaction—and fairly constantly so. When an association continues long enough for two people to become linked together by a relatively stable set of expectations, it is called a relationship.
People are bound within relationships by two types of bonds: expressive ties and instrumental ties. Expressive ties are social links formed when we emotionally invest ourselves in and commit ourselves to other people. Through association with people who are meaningful to us, we achieve a sense of security, love, acceptance, companionship, and personal worth. Instrumental ties are social links formed when we cooperate with other people to achieve some goal. Occasionally, this may mean working with instead of against competitors. More often, we simply cooperate with others to reach some end without endowing the relationship with any larger significance.
Sociologists have built on the distinction between expressive and instrumental ties to distinguish between two types of groups: primary and secondary. A primary group involves two or more people who enjoy a direct, intimate, cohesive relationship with one another. Expressive ties predominate in primary groups; we view the people as ends in themselves and valuable in their own right. A secondary group entails two or more people who are involved in an impersonal relationship and have come together for a specific, practical purpose. Instrumental ties predominate in secondary groups; we perceive people as means to ends rather than as ends in their own right. Sometimes primary group relationships evolve out of secondary group relationships. This happens in many work settings. People on the job often develop close relationships with coworkers as they come to share gripes, jokes, gossip, and satisfactions.
A number of conditions enhance the likelihood that primary groups will arise. First, group size is important. We find it difficult to get to know people personally when they are milling about and dispersed in large groups. In small groups we have a better chance to initiate contact and establish rapport with them. Second, face-to-face contact allows us to size up others. Seeing and talking with one another in close physical proximity makes possible a subtle exchange of ideas and feelings. And third, the probability that we will develop primary group bonds increases as we have frequent and continuous contact. Our ties with people often deepen as we interact with them across time and gradually evolve interlocking habits and interests.
Primary groups are fundamental to us and to society. First, primary groups are critical to the socialization process. Within them, infants and children are introduced to the ways of their society. Such groups are the breeding grounds in which we acquire the norms and values that equip us for social life. Sociologists view primary groups as bridges between individuals and the larger society because they transmit, mediate, and interpret a society's cultural patterns and provide the sense of oneness so critical for social solidarity.
Second, primary groups are fundamental because they provide the settings in which we meet most of our personal needs. Within them, we experience companionship, love, security, and an overall sense of well-being. Not surprisingly, sociologists find that the strength of a group's primary ties has implications for the group's functioning. For example, the stronger the primary group ties of a sports team playing together, the better their record is.
Third, primary groups are fundamental because they serve as powerful instruments for social control. Their members command and dispense many of the rewards that are so vital to us and that make our lives seem worthwhile. Should the use of rewards fail, members can frequently win by rejecting or threatening to ostracize those who deviate from the primary group's norms. For instance, some social groups employ shunning (a person can remain in the community, but others are forbidden to interact with the person) as a device to bring into line individuals whose behavior goes beyond that allowed by the particular group. Even more important, primary groups define social reality for us by structuring our experiences. By providing us with definitions of situations, they elicit from our behavior that conforms to group-devised meanings. Primary groups, then, serve both as carriers of social norms and as enforcers of them.
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Biological ClocksSurvival and successful reproduction usually require the activities of animals to be coordinated with predictable events around them. Consequently, the timing and rhythms of biological functions must closely match periodic events like the solar day, the tides, the lunar cycle, and the seasons. The relations between animal activity and these periods, particularly for the daily rhythms, have been of such interest and importance that a huge amount of work has been done on them and the special research field of chronobiology has emerged. Normally, the constantly changing levels of an animal's activity—sleeping, feeding, moving, reproducing, metabolizing, and producing enzymes and hormones, for example—are well coordinated with environmental rhythms, but the key question is whether the animal's schedule is driven by external cues, such as sunrise or sunset, or is instead dependent somehow on internal timers that themselves generate the observed biological rhythms. Almost universally, biologists accept the idea that all eukaryotes (a category that includes most organisms except bacteria and certain algae) have internal clocks. By isolating organisms completely from external periodic cues, biologists learned that organisms have internal clocks. For instance, apparently normal daily periods of biological activity were maintained for about a week by the fungus Neurospora when it was intentionally isolated from all geophysical timing cues while orbiting in a space shuttle. The continuation of biological rhythms in an organism without external cues attests to its having an internal clock.
When crayfish are kept continuously in the dark, even for four to five months, their compound eyes continue to adjust on a daily schedule for daytime and nighttime vision. Horseshoe crabs kept in the dark continuously for a year were found to maintain a persistent rhythm of brain activity that similarly adapts their eyes on a daily schedule for bright or for weak light. Like almost all daily cycles of animals deprived of environmental cues, those measured for the horseshoe crabs in these conditions were not exactly 24 hours. Such a rhythm whose period is approximately—but not exactly—a day is called circadian. For different individual horseshoe crabs, the circadian period ranged from 22.2 to 25.5 hours. A particular animal typically maintains its own characteristic cycle duration with great precision for many days. Indeed, stability of the biological clock's period is one of its major features, even when the organism's environment is subjected to considerable changes in factors, such as temperature, that would be expected to affect biological activity strongly. Further evidence for persistent internal rhythms appears when the usual external cycles are shifted—either experimentally or by rapid east-west travel over great distances. Typically, the animal's daily internally generated cycle of activity continues without change. As a result, its activities are shifted relative to the external cycle of the new environment. The disorienting effects of this mismatch between external time cues and internal schedules may persist, like our jet lag, for several days or weeks until certain cues such as the daylight/darkness cycle reset the organism's clock to synchronize with the daily rhythm of the new environment.
Animals need natural periodic signals like sunrise to maintain a cycle whose period is precisely 24 hours. Such an external cue not only coordinates an animal's daily rhythms with particular features of the local solar day but also—because it normally does so day after day-seems to keep the internal clock's period close to that of Earth's rotation. Yet despite this synchronization of the period of the internal cycle, the animal's timer itself continues to have its own genetically built-in period close to, but different from, 24 hours. Without the external cue, the difference accumulates and so the internally regulated activities of the biological day drift continuously, like the tides, in relation to the solar day. This drift has been studied extensively in many animals and in biological activities ranging from the hatching of fruit fly eggs to wheel running by squirrels. Light has a predominating influence in setting the clock. Even a fifteen-minute burst of light in otherwise sustained darkness can reset an animal's circadian rhythm. Normally, internal rhythms are kept in step by regular environmental cycles. For instance, if a homing pigeon is to navigate with its Sun compass, its clock must be properly set by cues provided by the daylight/darkness cycle.
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Methods of Studying Infant PerceptionIn the study of perceptual abilities of infants, a number of techniques are used to determine infants' responses to various stimuli. Because they cannot verbalize or fill out questionnaires, indirect techniques of naturalistic observation are used as the primary means of determining what infants can see, hear, feel, and so forth. Each of these methods compares an infant's state prior to the introduction of a stimulus with its state during or immediately following the stimulus. The difference between the two measures provides the researcher with an indication of the level and duration of the response to the stimulus. For example, if a uniformly moving pattern of some sort is passed across the visual field of a neonate (newborn), repetitive following movements of the eye occur. The occurrence of these eye movements provides evidence that the moving pattern is perceived at some level by the newborn. Similarly, changes in the infant's general level of motor activity —turning the head, blinking the eyes, crying, and so forth — have been used by researchers as visual indicators of the infant's perceptual abilities.
Such techniques, however, have limitations. First, the observation may be unreliable in that two or more observers may not agree that the particular response occurred, or to what degree it occurred. Second, responses are difficult to quantify. Often the rapid and diffuse movements of the infant make it difficult to get an accurate record of the number of responses. The third, and most potent, limitation is that it is not possible to be certain that the infant's response was due to the stimulus presented or to a change from no stimulus to a stimulus. The infant may be responding to aspects of the stimulus different than those identified by the investigator. Therefore, when observational assessment is used as a technique for studying infant perceptual abilities, care must be taken not to overgeneralize from the data or to rely on one or two studies as conclusive evidence of a particular perceptual ability of the infant.
Observational assessment techniques have become much more sophisticated, reducing the limitations just presented. Film analysis of the infant's responses, heart and respiration rate monitors, and nonnutritive sucking devices are used as effective tools in understanding infant perception. Film analysis permits researchers to carefully study the infant's responses over and over and in slow motion. Precise measurements can be made of the length and frequency of the infant's attention between two stimuli. Heart and respiration monitors provide the investigator with the number of heartbeats or breaths taken when a new stimulus is presented. Numerical increases are used as quantifiable indicators of heightened interest in the new stimulus. Increases in nonnutritive sucking were first used as an assessment measure by researchers in 1969. They devised an apparatus that connected a baby's pacifier to a counting device. As stimuli were presented, changes in the infant's sucking behavior were recorded. Increases in the number of sucks were used as an indicator of the infant's attention to or preference for a given visual display.
Two additional techniques of studying infant perception have come into vogue. The first is the habituation-dishabituation technique, in which a single stimulus is presented repeatedly to the infant until there is a measurable decline (habituation) in whatever attending behavior is being observed. At that point a new stimulus is presented, and any recovery (dishabituation) in responsiveness is recorded. If the infant fails to dishabituate and continues to show habituation with the new stimulus, it is assumed that the baby is unable to perceive the new stimulus as different. The habituation-dishabituation paradigm has been used most extensively with studies of auditory and olfactory perception in infants. The second technique relies on evoked potentials, which are electrical brain responses that may be related to a particular stimulus because of where they originate. Changes in the electrical pattern of the brain indicate that the stimulus is getting through to the infant's central nervous system and eliciting some form of response.
Each of the preceding techniques provides the researcher with evidence that the infant can detect or discriminate between stimuli. With these sophisticated observational assessment and electro-physiological measures, we know that the neonate of only a few days is far more perceptive than previously suspected. However, these measures are only "indirect" indicators of the infant's perceptual abilities.
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"Children and AdvertisingYoung children are trusting of commercial advertisements in the media, and advertisers have sometimes been accused of taking advantage of this trusting outlook. The Independent Television Commission, regulator of television advertising in the United Kingdom, has criticized advertisers for ""misleadingness""—creating a wrong impression either intentionally or unintentionally—in an effort to control advertisers' use of techniques that make it difficult for children to judge the true size, action, performance, or construction of a toy.
General concern about misleading tactics that advertisers employ is centered on the use of exaggeration. Consumer protection groups and parents believe that children are largely ill-equipped to recognize such techniques and that often exaggeration is used at the expense of product information. Claims such as ""the best"" or ""better than"" can be subjective and misleading; even adults may be unsure as to their meaning. They represent the advertiser's opinions about the qualities of their products or brand and, as a consequence, are difficult to verify. Advertisers sometimes offset or counterbalance an exaggerated claim with a disclaimer—a qualification or condition on the claim. For example, the claim that breakfast cereal has a health benefit may be accompanied by the disclaimer ""when part of a nutritionally balanced breakfast."" However, research has shown that children often have difficulty understanding disclaimers: children may interpret the phrase ""when part of a nutritionally balanced breakfast"" to mean that the cereal is required as a necessary part of a balanced breakfast. The author George Comstock suggested that less than a quarter of children between the ages of six and eight years old understood standard disclaimers used in many toy advertisements and that disclaimers are more readily comprehended when presented in both audio and visual formats. Nevertheless, disclaimers are mainly presented in audio format only.
Fantasy is one of the more common techniques in advertising that could possibly mislead a young audience. Child-oriented advertisements are more likely to include magic and fantasy than advertisements aimed at adults. In a content analysis of Canadian television, the author Stephen Kline observed that nearly all commercials for character toys featured fantasy play. Children have strong imaginations and the use of fantasy brings their ideas to life, but children may not be adept enough to realize that what they are viewing is unreal. Fantasy situations and settings are frequently used to attract children's attention, particularly in food advertising. Advertisements for breakfast cereals have, for many years, been found to be especially fond of fantasy techniques, with almost nine out of ten including such content. Generally, there is uncertainty as to whether very young children can distinguish between fantasy and reality in advertising. Certainly, rational appeals in advertising aimed at children are limited, as most advertisements use emotional and indirect appeals to psychological states or associations.
The use of celebrities such as singers and movie stars is common in advertising. The intention is for the positively perceived attributes of the celebrity to be transferred to the advertised product and for the two to become automatically linked in the audience's mind. In children's advertising, the ""celebrities"" are often animated figures from popular cartoons. In the recent past, the role of celebrities in advertising to children has often been conflated with the concept of host selling. Host selling involves blending advertisements with regular programming in a way that makes it difficult to distinguish one from the other. Host selling occurs, for example, when a children's show about a cartoon lion contains an ad in which the same lion promotes a breakfast cereal. The psychologist Dale Kunkel showed that the practice of host selling reduced children's ability to distinguish between advertising and program material. It was also found that older children responded more positively to products in host selling advertisements.
Regarding the appearance of celebrities in advertisements that do not involve host selling, the evidence is mixed. Researcher Charles Atkin found that children believe that the characters used to advertise breakfast cereals are knowledgeable about cereals, and children accept such characters as credible sources of nutritional information. This finding was even more marked for heavy viewers of television. In addition, children feel validated in their choice of a product when a celebrity endorses that product. A study of children in Hong Kong, however, found that the presence of celebrities in advertisements could negatively affect the children's perceptions of a product if the children did not like the celebrity in question. "
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Maya Water ProblemsTo understand the ancient Mayan people who lived in the area that is today southern Mexico and Central America and the ecological difficulties they faced, one must first consider their environment, which we think of as "jungle" or "tropical rainforest." This view is inaccurate, and the reason proves to be important. Properly speaking, tropical rainforests grow in high-rainfall equatorial areas that remain wet or humid all year round. But the Maya homeland lies more than sixteen hundred kilometers from the equator, at latitudes 17 to 22 degrees north, in a habitat termed a "seasonal tropical forest." That is, while there does tend to be a rainy season from May to October, there is also a dry season from January through April. If one focuses on the wet months, one calls the Maya homeland a "seasonal tropical forest"; if one focuses on the dry months, one could instead describe it as a "seasonal desert."
From north to south in the Yucatan Peninsula, where the Maya lived, rainfall ranges from 18 to 100 inches (457 to 2,540 millimeters) per year, and the soils become thicker, so that the southern peninsula was agriculturally more productive and supported denser populations. But rainfall in the Maya homeland is unpredictably variable between years; some recent years have had three or four times more rain than other years. As a result, modern farmers attempting to grow corn in the ancient Maya homelands have faced frequent crop failures, especially in the north. The ancient Maya were presumably more experienced and did better, but nevertheless they too must have faced risks of crop failures from droughts and hurricanes.
Although southern Maya areas received more rainfall than northern areas, problems of water were paradoxically more severe in the wet south. While that made things hard for ancient Maya living in the south, it has also made things hard for modern archaeologists who have difficulty understanding why ancient droughts caused bigger problems in the wet south than in the dry north. The likely explanation is that an area of underground freshwater underlies the Yucatan Peninsula, but surface elevation increases from north to south, so that as one moves south the land surface lies increasingly higher above the water table. In the northern peninsula the elevation is sufficiently low that the ancient Maya were able to reach the water table at deep sinkholes called cenotes, or at deep caves. In low-elevation north coastal areas without sinkholes, the Maya would have been able to get down to the water table by digging wells up to 75 feet (22 meters) deep. But much of the south lies too high above the water table for cenotes or wells to reach down to it. Making matters worse, most of the Yucatan Peninsula consists of karst, a porous sponge-like limestone terrain where rain runs straight into the ground and where little or no surface water remains available.
How did those dense southern Maya populations deal with the resulting water problem? It initially surprises us that many of their cities were not built next to the rivers but instead on high terrain in rolling uplands. The explanation is that the Maya excavated depressions, or modified natural depressions, and then plugged up leaks in the karst by plastering the bottoms of the depressions in order to create reservoirs, which collected rain from large plastered catchment basins and stored it for use in the dry season. For example, reservoirs at the Maya city of Tikal held enough water to meet the drinking water needs of about 10,000 people for a period of 18 months. At the city of Coba the Maya built dikes around a lake in order to raise its level and make their water supply more reliable. But the inhabitants of Tikal and other cities dependent on reservoirs for drinking water would still have been in deep trouble if 18 months passed without rain in a prolonged drought. A shorter drought in which they exhausted their stored food supplies might already have gotten them in deep trouble, because growing crops required rain rather than reservoirs.
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Pastoralism in Ancient Inner EurasiaPastoralism is a lifestyle in which economic activity is based primarily on livestock. Archaeological evidence suggests that by 3000 B.C., and perhaps even earlier, there had emerged on the steppes of Inner Eurasia the distinctive types of pastoralism that were to dominate the region's history for several millennia. Here, the horse was already becoming the animal of prestige in many regions, though sheep, goats, and cattle could also play a vital role. It is the use of horses for transportation and warfare that explains why Inner Eurasian pastoralism proved the most mobile and the most militaristic of all major forms of pastoralism. The emergence and spread of pastoralism had a profound impact on the history of Inner Eurasia, and also, indirectly, on the parts of Asia and Europe just outside this area. In particular, pastoralism favors a mobile lifestyle, and this mobility helps to explain the impact of pastoralist societies on this part of the world.
The mobility of pastoralist societies reflects their dependence on animal-based foods. While agriculturalists rely on domesticated plants, pastoralists rely on domesticated animals. As a result, pastoralists, like carnivores in general, occupy a higher position on the food chain. All else being equal, this means they must exploit larger areas of land than do agriculturalists to secure the same amount of food, clothing, and other necessities. So pastoralism is a more extensive lifeway than farming is. However, the larger the terrain used to support a group, the harder it is to exploit that terrain while remaining in one place. So, basic ecological principles imply a strong tendency within pastoralist lifeways toward nomadism (a mobile lifestyle). As the archaeologist Roger Cribb puts it, “The greater the degree of pastoralism, the stronger the tendency toward nomadism.” A modern Turkic nomad interviewed by Cribb commented: "The more animals you have, the farther you have to move."
Nomadism has further consequences. It means that pastoralist societies occupy and can influence very large territories. This is particularly true of the horse pastoralism that emerged in the Inner Eurasian steppes, for this was the most mobile of all major forms of pastoralism. So, it is no accident that with the appearance of pastoralist societies there appear large areas that share similar cultural, ecological, and even linguistic features. By the late fourth millennium B.C., there is already evidence of large culture zones reaching from Eastern Europe to the western borders of Mongolia. Perhaps the most striking sign of mobility is the fact that by the third millennium B.C., most pastoralists in this huge region spoke related languages ancestral to the modern Indo-European languages. The remarkable mobility and range of pastoral societies explain, in part, why so many linguists have argued that the Indo-European languages began their astonishing expansionist career not among farmers in Anatolia (present-day Turkey), but among early pastoralists from Inner Eurasia. Such theories imply that the Indo-European languages evolved not in Neolithic (10,000 to 3,000 B.C.) Anatolia, but among the foraging communities of the cultures in the region of the Don and Dnieper rivers, which took up stock breeding and began to exploit the neighboring steppes.
Nomadism also subjects pastoralist communities to strict rules of portability. If you are constantly on the move, you cannot afford to accumulate large material surpluses. Such rules limit variations in accumulated material goods between pastoralist households (though they may also encourage a taste for portable goods of high value such as silks or jewelry). So, by and large, nomadism implies a high degree of self-sufficiency and inhibits the appearance of an extensive division of labor. Inequalities of wealth and rank certainly exist, and have probably existed in most pastoralist societies, but except in periods of military conquest, they are normally too slight to generate the stable, hereditary hierarchies that are usually implied by the use of the term class. Inequalities of gender have also existed in pastoralist societies, but they seem to have been softened by the absence of steep hierarchies of wealth in most communities, and also by the requirement that women acquire most of the skills of men, including, often, their military skills.
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A Warm Blooded TurtleWhen it comes to physiology, the leatherback turtle is, in some ways, more like a reptilian whale than a turtle. It swims farther into the cold of the northern and southern oceans than any other sea turtle, and it deals with the chilly waters in a way unique among reptiles.
A warm-blooded turtle may seem to be a contradiction in terms. Nonetheless, an adult leatherback can maintain a body temperature of between 25 and 26°C (77-79°F) in seawater that is only 8°C (46.4°F). Accomplishing this feat requires adaptations both to generate heat in the turtle’s body and to keep it from escaping into the surrounding waters. Leatherbacks apparently do not generate internal heat the way we do, or the way birds do, as a by-product of cellular metabolism. A leatherback may be able to pick up some body heat by basking at the surface; its dark, almost black body color may help it to absorb solar radiation. However, most of its internal heat comes from the action of its muscles.
Leatherbacks keep their body heat in three different ways. The first, and simplest, is size. The bigger the animal is, the lower its surface-to-volume ratio; for every ounce of body mass, there is proportionately less surface through which heat can escape. An adult leatherback is twice the size of the biggest cheloniid sea turtles and will therefore take longer to cool off. Maintaining a high body temperature through sheer bulk is called gigantothermy. It works for elephants, for whales, and, perhaps, it worked for many of the larger dinosaurs. It apparently works, in a smaller way, for some other sea turtles. Large loggerhead and green turtles can maintain their body temperature at a degree or two above that of the surrounding water, and gigantothermy is probably the way they do it. Muscular activity helps, too, and an actively swimming green turtle may be 7°C (12.6°F) warmer than the waters it swims through.
Gigantothermy, though, would not be enough to keep a leatherback warm in cold northern waters. It is not enough for whales, which supplement it with a thick layer of insulating blubber (fat). Leatherbacks do not have blubber, but they do have a reptilian equivalent: thick, oil-saturated skin, with a layer of fibrous, fatty tissue just beneath it. Insulation protects the leatherback everywhere but on its head and flippers. Because the flippers are comparatively thin and blade-like, they are the one part of the leatherback that is likely to become chilled. There is not much that the turtle can do about this without compromising the aerodynamic shape of the flipper. The problem is that as blood flows through the turtle’s flippers, it risks losing enough heat to lower the animal’s central body temperature when it returns. The solution is to allow the flippers to cool down without drawing heat away from the rest of the turtle’s body. The leatherback accomplishes this by arranging the blood vessels in the base of its flipper into a countercurrent exchange system.
In a countercurrent exchange system, the blood vessels carrying cooled blood from the flippers run close enough to the blood vessels carrying warm blood from the body to pick up some heat from the warmer blood vessels; thus, the heat is transferred from the outgoing to the ingoing vessels before it reaches the flipper itself. This is the same arrangement found in an old-fashioned steam radiator, in which the coiled pipes pass heat back and forth as water courses through them. The leatherback is certainly not the only animal with such an arrangement; gulls have a countercurrent exchange in their legs. That is why a gull can stand on an ice floe without freezing.
All this applies, of course, only to an adult leatherback. Hatchlings are simply too small to conserve body heat, even with insulation and countercurrent exchange systems. We do not know how old, or how large, a leatherback has to be before it can switch from a cold-blooded to a warm-blooded mode of life. Leatherbacks reach their immense size in a much shorter time than it takes other sea turtles to grow. Perhaps their rush to adulthood is driven by a simple need to keep warm.
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Mass ExtinctionsCases in which many species become extinct within a geologically short interval of time are called mass extinctions. There was one such event at the end of the Cretaceous period (around 70 million years ago). There was another, even larger, mass extinction at the end of the Permian period (around 250 million years ago). The Permian event has attracted much less attention than other mass extinctions because mostly unfamiliar species perished at that time.
The fossil record shows at least five mass extinctions in which many families of marine organisms died out. The rates of extinction happening today are as great as the rates during these mass extinctions. Many scientists have therefore concluded that a sixth great mass extinction is currently in progress.
What could cause such high rates of extinction? There are several hypotheses, including warming or cooling of Earth, changes in seasonal fluctuations or ocean currents, and changing positions of the continents. Biological hypotheses include ecological changes brought about by the evolution of cooperation between insects and flowering plants or of bottom-feeding predators in the oceans. Some of the proposed mechanisms required a very brief period during which all extinctions suddenly took place; other mechanisms would be more likely to have taken place more gradually, over an extended period, or at different times on different continents. Some hypotheses fail to account for simultaneous extinctions on land and in the seas. Each mass extinction may have had a different cause. Evidence points to hunting by humans and habitat destruction as the likely causes for the current mass extinction.
American paleontologists David Raup and John Sepkoski, who have studied extinction rates in a number of fossil groups, suggest that episodes of increased extinction have recurred periodically, approximately every 26 million years since the mid-Cretaceous period. The late Cretaceous extinction of the dinosaurs and ammonoids was just one of the more drastic in a whole series of such recurrent extinction episodes. The possibility that mass extinctions may recur periodically has given rise to such hypotheses as that of a companion star with a long-period orbit deflecting other bodies from their normal orbits, making some of them fall to Earth as meteors and causing widespread devastation upon impact.
Of the various hypotheses attempting to account for the late Cretaceous extinctions, the one that has attracted the most attention in recent years is the asteroid-impact hypothesis first suggested by Luis and Walter Alvarez. According to this hypothesis, Earth collided with an asteroid with an estimated diameter of 10 kilometers, or with several asteroids, the combined mass of which was comparable. The force of collision spewed large amounts of debris into the atmosphere, darkening the skies for several years before the finer particles settled. The reduced level of photosynthesis led to a massive decline in plant life of all kinds, and this caused massive starvation first of herbivores and subsequently of carnivores. The mass extinction would have occurred very suddenly under this hypothesis.
One interesting test of the Alvarez hypothesis is based on the presence of the rare-earth element iridium (Ir). Earth’s crust contains very little of this element, but most asteroids contain a lot more. Debris thrown into the atmosphere by an asteroid collision would presumably contain large amounts of iridium, and atmospheric currents would carry this material all over the globe. A search of sedimentary deposits that span the boundary between the Cretaceous and Tertiary periods shows that there is a dramatic increase in the abundance of iridium briefly and precisely at this boundary. This iridium anomaly offers strong support for the Alvarez hypothesis even though no asteroid itself has ever been recovered.
An asteroid of this size would be expected to leave an immense crater, even if the asteroid itself was disintegrated by the impact. The intense heat of the impact would produce heat-shocked quartz in many types of rock. Also, large blocks thrown aside by the impact would form secondary craters surrounding the main crater. To date, several such secondary craters have been found along Mexico’s Yucatan Peninsula, and heat-shocked quartz has been found both in Mexico and in Haiti. A location called Chicxulub, along the Yucatan coast, has been suggested as the primary impact site.
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Glacier FormationGlaciers are slowly moving masses of ice that have accumulated on land in areas where more snowfalls during a year than melts. Snow falls as hexagonal crystals, but once on the ground, snow is soon transformed into a compacted mass of smaller, rounded grains. As the air space around them is lessened by compaction and melting, the grains become denser. With further melting, refreezing, and increased weight from newer snowfall above, the snow reaches a granular recrystallized stage intermediate between flakes and ice known as firn. With additional time, pressure, and refrozen meltwater from above, the small firn granules become larger, interlocked crystals of blue glacial ice. When the ice is thick enough, usually over 30 meters, the weight of the snow and firn will cause the ice crystals toward the bottom to become plastic and to flow outward or downward from the area of snow accumulation.
Glaciers are open systems, with snow as the system’s input and meltwater as the system's main output. The glacial system is governed by two basic climatic variables: precipitation and temperature. For a glacier to grow or maintain its mass, there must be sufficient snowfall to match or exceed the annual loss through melting, evaporation, and calving, which occurs when the glacier loses solid chunks as icebergs to the sea or to large lakes. If summer temperatures are high for too long, then all the snowfall from the previous winter will melt. Surplus snowfall is essential for a glacier to develop. A surplus allows snow to accumulate and for the pressure of snow accumulated over the years to transform buried snow into glacial ice with a depth great enough for the ice to flow. Glaciers are sometimes classified by temperature as faster-flowing temperate glaciers or as slower-flowing polar glaciers.
Glaciers are part of Earth’s hydrologic cycle and are second only to the oceans in the total amount of water contained. About 2 percent of Earth’s water is currently frozen as ice. Two percent may be a deceiving figure, however, since over 80 percent of the world’s freshwater is locked up as ice in glaciers, with the majority of it in Antarctica. The total amount of ice is even more awesome if we estimate the water released upon the hypothetical melting of the world’s glaciers. Sea level would rise about 60 meters. This would change the geography of the planet considerably. In contrast, should another ice age occur, sea level would drop drastically. During the last ice age, sea level dropped about 120 meters.
When snowfalls on high mountains or in polar regions, it may become part of the glacial system. Unlike rain, which returns rapidly to the sea or atmosphere, the snow that becomes part of a glacier is involved in a much more slowly cycling system. Here water may be stored in ice form for hundreds or even hundreds of thousands of years before being released again into the liquid water system as meltwater. In the meantime, however, this ice is not static. Glaciers move slowly across the land with tremendous energy, carving into even the hardest rock formations and thereby reshaping the landscape as they engulf, push, drag, and finally deposit rock debris in places far from its original location. As a result, glaciers create a great variety of landforms that remain long after the surface is released from its icy covering.
Throughout most of Earth’s history, glaciers did not exist, but at the present time about 10 percent of Earth’s land surface is covered by glaciers. Present-day glaciers are found in Antarctica, in Greenland, and at high elevations on all the continents except Australia. In the recent past, from about 2.4 million to about 10,000 years ago, nearly a third of Earth’s land area was periodically covered by ice thousands of meters thick. In the much more distant past, other ice ages have occurred.
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Trade and the Ancient Middle EastTrade was the mainstay of the urban economy in the Middle East, as caravans negotiated the surrounding desert, restricted only by access to water and by mountain ranges. This has been so since ancient times, partly due to the geology of the area, which is mostly limestone and sandstone, with few deposits of metallic ore and other useful materials Ancient demands for obsidian (a black volcanic rock useful for making mirrors and tools) led to trade with Armenia to the north, while jade for cutting tools was brought from Turkistan, and the precious stone lapis lazuli was imported from Afghanistan. One can trace such expeditions back to ancient Sumeria, the earliest known Middle Eastern civilization. Records show merchant caravans and trading posts set up by the Sumerians in the surrounding mountains and deserts of Persia and Arabia, where they traded grain for raw materials, such as timber and stones, as well as for metals and gems.
Reliance on trade had several important consequences. Production was generally in the hands of skilled individual artisans doing piecework under the tutelage of a master who was also the shop owner. In these shops differences of rank were blurred as artisans and masters labored side by side in the same modest establishment, were usually members of the same guild and religious sect, lived in the same neighborhoods, and often had assumed (or real) kinship relationships. The worker was bound to the master by a mutual contract that either one could repudiate, and the relationship was conceptualized as one of partnership.
This mode of craft production favored the growth of self-governing and ideologically egalitarian craft guilds everywhere in the Middle Eastern city. These were essentially professional associations that provided for the mutual aid and protection of their members, and allowed for the maintenance of professional standards. The growth of independent guilds was furthered by the fact that surplus was not a result of domestic craft production but resulted primarily from international trading; the government left working people to govern themselves, much as shepherds of tribal confederacies were left alone by their leaders. In the multiplicity of small-scale local egalitarian or quasi-egalitarian organizations for fellowship, worship, and production that flourished in this laissez-faire environment, individuals could interact with one another within a community of harmony and ideological equality, following their own popularly elected leaders and governing themselves by shared consensus while minimizing distinctions of wealth and power.
The mercantile economy was also characterized by a peculiar moral stance that is typical of people who live by trade—an attitude that is individualistic, calculating, risk taking, and adaptive to circumstances. As among tribespeople, personal relationships and a careful weighing of character have always been crucial in a mercantile economy with little regulation, where one's word is one's bond and where informal ties of trust cement together an international trade network. Nor have merchants and artisans ever had much tolerance for aristocratic professions of moral superiority, favoring instead an egalitarian ethic of the open market, where steady hard work, the loyalty of one's fellows, and ntrepreneurial skill make all the difference. And, like the pastoralists, Middle Eastern merchants and artisans unhappy with their environment could simply pack up and leave for greener pastures—an act of self-assertion wholly impossible in most other civilizations throughout history.
Dependence on long-distance trade also meant that the great empires of the Middle East were built both literally and figuratively on shifting sand. The central state, though often very rich and very populous, was intrinsically fragile, since the development of new international trade routes could undermine the monetary base and erode state power, as occurred when European seafarers circumvented Middle Eastern merchants after Vasco da Gama's voyage around Africa in the late fifteenth century opened up a southern route. The ecology of the region also permitted armed predators to prowl the surrounding barrens, which were almost impossible for a state to control. Peripheral peoples therefore had a great advantage in their dealings with the center, making government authority insecure and anxious.
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Development of the Periodic TableThe periodic table is a chart that reflects the periodic recurrence of chemical and physical properties of the elements when the elements are arranged in order of increasing atomic number (the number of protons in the nucleus). It is a monumental scientific achievement, and its development illustrates the essential interplay between observation, prediction, and testing required for scientific progress. In the 1800's scientists were searching for new elements. By the late 1860's more than 60 chemical elements had been identified, and much was known about their descriptive chemistry. Various proposals were put forth to arrange the elements into groups based on similarities in chemical and physical properties. The next step was to recognize a connection between group properties (physical or chemical similarities) and atomic mass (the measured mass of an individual atom of an element). When the elements known at the time were ordered by increasing atomic mass, it was found that successive elements belonged to different chemical groups and that the order of the groups in this sequence was fixed and repeated itself at regular intervals. Thus when the series of elements was written so as to begin a new horizontal row with each alkali metal, elements of the same groups were automatically assembled in vertical columns in a periodic table of the elements. This table was the forerunner of the modern table.
When the German chemist Lothar Meyer and (independently) the Russian Dmitry Mendeleyev first introduced the periodic table in 1869-70, one-third of the naturally occurring chemical elements had not yet been discovered. Yet both chemists were sufficiently farsighted to leave gaps where their analyses of periodic physical and chemical properties indicated that new elements should be located. Mendeleyev was bolder than Meyer and even assumed that if a measured atomic mass put an element in the wrong place in the table, the atomic mass was wrong. In some cases this was true. Indium, for example, had previously been assigned an atomic mass between those of arsenic and selenium. Because there is no space in the periodic table between these two elements, Mendeleyev suggested that the atomic mass of indium be changed to a completely different value, where it would fill an empty space between cadmium and tin. In fact, subsequent work has shown that in a periodic table, elements should not be ordered strictly by atomic mass. For example, tellurium comes before iodine in the periodic table, even though its atomic mass is slightly greater. Such anomalies are due to the relative abundance of the "isotopes" or varieties of each element. All the isotopes of a given element have the same number of protons, but differ in their number of neutrons, and hence in their atomic mass. The isotopes of a given element have the same chemical properties but slightly different physical properties. We now know that atomic number (the number of protons in the nucleus), not atomic mass number (the number of protons and neutrons), determines chemical behavior.
Mendeleyev went further than Meyer in another respect: he predicted the properties of six elements yet to be discovered. For example, a gap just below aluminum suggested a new element would be found with properties analogous to those of aluminum. Mendeleyev designated this element "eka-aluminum" (eka is the Sanskrit word for "next") and predicted its properties. Just five years later an element with the proper atomic mass was isolated and named gallium by its discoverer. The close correspondence between the observed properties of gallium and Mendeleyev’s predictions for eka-aluminum lent strong support to the periodic law. Additional support came in 1885 when eka-silicon, which had also been described in advance by Mendeleyev, was discovered and named germanium.
The structure of the periodic table appeared to limit the number of possible elements. It was therefore quite surprising when John William Strut ，Lord Rayleigh, discovered a gaseous element in 1894 that did not fit into the previous classification scheme. A century earlier, Henry Cavendish had noted the existence of a residual gas when oxygen and nitrogen are removed from air, but its importance had not been realized. Together with William Ramsay, Rayleigh isolated the gas (separating it from other substances into its pure state) and named it argon. Ramsay then studied a gas that was present in natural gas deposits and discovered that it was helium, an element whose presence in the Sun had been noted earlier in the spectrum of sunlight but that had not previously been known on Earth. Rayleigh and Ramsay postulated the existence of a new group of elements, and in 1898 other members of the series (neon, krypton, and xenon) were isolated.
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Planets in Our Solar SystemThe Sun is the hub of a huge rotating system consisting of nine planets, their satellites, and numerous small bodies, including asteroids, comets, and meteoroids. An estimated 99.85 percent of the mass of our solar system is contained within the Sun, while the planets collectively make up most of the remaining 0.15 percent. The planets, in order of their distance from the Sun, are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. Under the control of the Sun's gravitational force, each planet maintains an elliptical orbit and all of them travel in the same direction.
The planets in our solar system fall into two groups: the terrestrial (Earth-like) planets (Mercury, Venus, Earth, and Mars) and the Jovian (Jupiter-like) planets (Jupiter, Saturn, Uranus, and Neptune). Pluto is not included in either category, because its great distance from Earth and its small size make this planet's true nature a mystery.
The most obvious difference between the terrestrial and the Jovian planets is their size. The largest terrestrial planet, Earth has a diameter only one quarter as great as the diameter of the smallest Jovian planet, Neptune, and its mass is only one seventeenth as great. Hence, the Jovian planets are often called giants. Also, because of their relative locations, the four Jovian planets are known as the outer planets, while the terrestrial planets are known as the inner planets. There appears to be a correlation between the positions of these planets and their sizes.
Other dimensions along which the two groups differ markedly are density and composition. The densities of the terrestrial planets average about 5 times the density of water, whereas the Jovian planets have densities that average only 1.5 times the density of water. One of the outer planets, Saturn, has a density of only 0.7 that of water, which means that Saturn would float in water. Variations in the composition of the planets are largely responsible for the density differences. The substances that make up both groups of planets are divided into three groups—gases, rocks, and ices—based on their melting points. The terrestrial planets are mostly rocks: dense rocky and metallic material, with minor amounts of gases. The Jovian planets, on the other hand, contain a large percentage of the gases hydrogen and helium, with varying amounts of ices: mostly water, ammonia, and methane ices.
The Jovian planets have very thick atmospheres consisting of varying amounts of hydrogen, helium, methane, and ammonia. By comparison, the terrestrial planets have meager atmospheres at best. A planet's ability to retain an atmosphere depends on its temperature and mass. Simply stated, a gas molecule can "evaporate" from a planet if it reaches a speed known as the escape velocity. For Earth, this velocity is 11 kilometers per second. Any material, including a rocket, must reach this speed before it can leave Earth and go into space. The Jovian planets, because of their greater masses and thus higher surface gravities, have higher escape velocities (21-60 kilometers per second) than the terrestrial planets. Consequently, it is more difficult for gases to "evaporate" from them. Also, because the molecular motion of a gas depends on temperature, at the low temperatures of the Jovian planets even the lightest gases are unlikely to acquire the speed needed to escape. On the other hand, a comparatively warm body with a small surface gravity, like Earth's moon, is unable to hold even the heaviest gas and thus lacks an atmosphere. The slightly larger terrestrial planets Earth, Venus, and Mars retain some heavy gases like carbon dioxide, but even their atmospheres make up only an infinitesimally small portion of their total mass.
The orderly nature of our solar system leads most astronomers to conclude that the planets formed at essentially the same time and from the same material as the Sun. It is hypothesized that the primordial cloud of dust and gas from which all the planets are thought to have condensed had a composition somewhat similar to that of Jupiter. However, unlike Jupiter, the terrestrial planets today are nearly void of light gases and ices. The explanation may be that the terrestrial planets were once much larger and richer in these materials but eventually lost them because of these bodies' relative closeness to the Sun, which meant that their temperatures were relatively high.
R17P1
Europe's Early Sea Trade with AsiaIn the fourteenth century, a number of political developments cut Europe's overland trade routes to southern and eastern Asia, with which Europe had had important and highly profitable commercial ties since the twelfth century. This development, coming as it did when the bottom had fallen out of the European economy, provided an impetus to a long-held desire to secure direct relations with the East by establishing a sea trade. Widely reported, if somewhat distrusted, accounts by figures like the famous traveler from Venice, Marco Polo, of the willingness of people in China to trade with Europeans and of the immensity of the wealth to be gained by such contact made the idea irresistible. Possibilities for trade seemed promising, but no hope existed for maintaining the traditional routes over land A new way had to be found.
The chief problem was technological: How were the Europeans to reach the East? Europe's maritime tradition had developed in the context of easily navigable seas—the Mediterranean, the Baltic, and, to a lesser extent, the North Sea between England and the Continent—not of vast oceans. New types of ships were needed, new methods of finding one's way, new techniques for financing so vast a scheme. The sheer scale of the investment it took to begin commercial expansion at sea reflects the immensity of the profits that such East-West trade could create. Spices were the most sought-after commodities. Spices not only dramatically improved the taste of the European diet but also were used to manufacture perfumes and certain medicines. But even high-priced commodities like spices had to be transported in large bulk in order to justify the expense and trouble of sailing around the African continent all the way to India and China.
The principal seagoing ship used throughout the Middle Ages was the galley, a long, low ship fitted with sails but driven primarily by oars. The largest galleys had as many as 50 oarsmen Since they had relatively shallow hulls, they were unstable when driven by sail or when on rough water: hence they were unsuitable for the voyage to the East. Even if they hugged the African coastline, they had little chance of surviving a crossing of the Indian Ocean. Shortly after 1400, shipbuilders began developing a new type of vessel properly designed to operate in rough, open water: the caravel. It had a wider and deeper hull than the galley and hence could carry more cargo: increased stability made it possible to add multiple masts and sails. In the largest caravels, two main masts held large square sails that provided the bulk of the thrust driving the ship forward, while a smaller forward mast held a triangular-shaped sail, called a lateen sail, which could be moved into a variety of positions to maneuver the ship.
The astrolabe had long been the primary instrument for navigation, having been introduced in the eleventh century. It operated by measuring the height of the Sun and the fixed stars: by calculating the angles created by these points, it determined the degree of latitude at which one stood (The problem of determining longitude, though, was not solved until the eighteenth century.) By the early thirteenth century. Western Europeans had also developed and put into use the magnetic compass, which helped when clouds obliterated both the Sun and the stars. Also beginning in the thirteenth century, there were new maps refined by precise calculations and the reports of sailors that made it possible to trace one's path with reasonable accuracy. Certain institutional and practical norms had become established as well. A maritime code known as the Consulate of the Sea, which originated in the western Mediterranean region in the fourteenth century, won acceptance by a majority of sea goers as the normative code for maritime conduct; it defined such matters as the authority of a ship's officers, protocols of command, pay structures, the rights of sailors, and the rules of engagement when ships met one another on the sea-lanes. Thus by about 1400 the key elements were in place to enable Europe to begin its seaward adventure.
R17P2
Animal Signals in the Rain ForestThe daytime quality of light in forests varies with the density of the vegetation, the angle of the Sun, and the amount of cloud in the sky. Both animals and plants have different appearances in these various lighting conditions. A color or pattern that is relatively indistinct in one kind of light may be quite conspicuous in another.
In the varied and constantly changing light environment of the forest, an animal must be able to send visual signals to members of its own species and at the same time avoid being detected by predators. An animal can hide from predators by choosing the light environment in which its pattern is least visible. This may require moving to different parts of the forest at different times of the day or under different weather conditions, or it may be achieved by changing color according to the changing light conditions. Many species of amphibians (frogs and toads) and reptiles (lizards and snakes) are able to change their color patterns to camouflage themselves. Some also signal by changing color. The chameleon lizard has the most striking ability to do this. Some chameleon species can change from a rather dull appearance to a full riot of carnival colors in seconds. By this means, they signal their level of aggression or readiness to mate.
Other species take into account the changing conditions of light by performing their visual displays only when the light is favorable. A male bird of paradise may put himself in the limelight by displaying his spectacular plumage in the best stage setting to attract a female. Certain butterflies move into spots of sunlight that have penetrated to the forest floor and display by opening and closing their beautifully patterned wings in the bright spotlights. They also compete with each other for the best spot of sunlight.
Very little light filters through the canopy of leaves and branches in a rain forest to reach ground level—or close to the ground—and at those levels the yellow-to-green wavelengths predominate. A signal might be most easily seen if it is maximally bright. In the green-to-yellow lighting conditions of the lowest levels of the forest, yellow and green would be the brightest colors, but when an animal is signaling, these colors would not be very visible if the animal was sitting in an area with a yellowish or greenish background. The best signal depends not only on its brightness but also on how well it contrasts with the background against which it must be seen. In this part of the rain forest, therefore, red and orange are the best colors for signaling, and they are the colors used in signals by the ground-walking Australian brush turkey. This species, which lives in the rain forests and scrublands of the east coast of Australia, has a brown-to-black plumage with bare, bright-red skin on the head and neck and a neck collar of orange-yellow loosely hanging skin. During courtship and aggressive displays, the turkey enlarges its colored neck collar by inflating sacs in the neck region and then flings about a pendulous part of the colored signaling apparatus as it utters calls designed to attract or repel. This impressive display is clearly visible in the light spectrum illuminating the forest floor.
Less colorful birds and animals that inhabit the rain forest tend to rely on other forms of signaling other than the visual, particularly over long distances. The piercing cries of the rhinoceros hornbill characterize the Southeast Asian rain forest, as do the unmistakable calls of the gibbons. In densely wooded environments, sound is the best means of communication over distance because in comparison with light, it travels with little impediment from trees and other vegetation. In forests, visual signals can be seen only at short distances, where they are not obstructed by trees. The male riflebird exploits12 both of these modes of signaling simultaneously in his courtship display. The sounds made as each wing is opened carry extremely well over distance and advertise his presence widely. The ritualized visual display communicates in close quarters when a female has approached.
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Symbiotic RelationshipsA symbiotic relationship is an interaction between two or more species in which one species lives in or on another species. There are three main types of symbiotic relationships: parasitism, commensalism, and mutualism. The first and the third can be key factors in the structure of a biological community; that is, all the populations of organisms living together and potentially interacting in a particular area.
Parasitism is a kind of predator-prey relationship in which one organism, the parasite, derives its food at the expense of its symbiotic associate, the host. Parasites are usually smaller than their hosts. An example of a parasite is a tapeworm that lives inside the intestines of a larger animal and absorbs nutrients from its host. Natural selection favors the parasites that are best able to find and feed on hosts. At the same time, defensive abilities of hosts are also selected for. As an example, plants make chemicals toxic to fungal and bacterial parasites, along with ones toxic to predatory animals (sometimes they are the same chemicals). In vertebrates, the immune system provides a multiple defense against internal parasites.
At times, it is actually possible to watch the effects of natural selection in host-parasite relationships. For example, Australia during the 1940 s was overrun by hundreds of millions of European rabbits. The rabbits destroyed huge expanses of Australia and threatened the sheep and cattle industries. In 1950, myxoma virus, a parasite that affects rabbits, was deliberately introduced into Australia to control the rabbit population. Spread rapidly by mosquitoes, the virus devastated the rabbit population. The virus was less deadly to the offspring of surviving rabbits, however, and it caused less and less harm over the years. Apparently, genotypes (the genetic make-up of an organism) in the rabbit population were selected that were better able to resist the parasite. Meanwhile, the deadliest strains of the virus perished with their hosts as natural selection favored strains that could infect hosts but not kill them. Thus, natural selection stabilized this host-parasite relationship.
In contrast to parasitism, in commensalism, one partner benefits without significantly affecting the other. Few cases of absolute commensalism probably exist, because it is unlikely that one of the partners will be completely unaffected. Commensal associations sometimes involve one species' obtaining food that is inadvertently exposed by another. For instance, several kinds of birds feed on insects flushed out of the grass by grazing cattle. It is difficult to imagine how this could affect the cattle, but the relationship may help or hinder them in some way not yet recognized.
The third type of symbiosis, mutualism, benefits both partners in the relationship Legume plants and their nitrogen-fixing bacteria, and the interactions between flowering plants and their pollinators, are examples of mutualistic association. In the first case, the plants provide the bacteria with carbohydrates and other organic compounds, and the bacteria have enzymes that act as catalysts that eventually add nitrogen to the soil, enriching it. In the second case, pollinators (insects, birds) obtain food from the flowering plant, and the plant has its pollen distributed and seeds dispersed much more efficiently than they would be if they were carried by the wind only. Another example of mutualism would be the bull's horn acacia tree, which grows in Central and South America. The tree provides a place to live for ants of the genus Pseudomyrmex. The ants live in large, hollow thorns and eat sugar secreted by the tree. The ants also eat yellow structures at the tip of leaflets: these are protein rich and seem to have no function for the tree except to attract ants. The ants benefit the host tree by attacking virtually anything that touches it. They sting other insects and large herbivores (animals that eat only plants) and even clip surrounding vegetation that grows near the tree. When the ants are removed, the trees usually die, probably because herbivores damage them so much that they are unable to compete with surrounding vegetation for light and growing space.
The complex interplay of species in symbiotic relationships highlights an important point about communities: Their structure depends on a web of diverse connections among organisms.
R18P1
Industrialization in the Netherlands and ScandinaviaWhile some European countries, such as England and Germany, began to industrialize in the eighteenth century, the Netherlands and the Scandinavian countries of Denmark, Norway, and Sweden developed later. All four of these countries lagged considerably behind in the early nineteenth century. However, they industrialized rapidly in the second half of the century, especially in the last two or three decades. In view of their later start and their lack of coal—undoubtedly the main reason they were not among the early industrializers—it is important to understand the sources of their success.
All had small populations. At the beginning of the nineteenth century, Denmark and Norway had fewer than 1 million people, while Sweden and the Netherlands had fewer than 2.5 million inhabitants. All exhibited moderate growth rates in the course of the century (Denmark the highest and Sweden the lowest), but all more than doubled in population by 1900. Density varied greatly. The Netherlands had one of the highest population densities in Europe, whereas Norway and Sweden had the lowest Denmark was in between but closer to the Netherlands.
Considering human capital as a characteristic of the population, however, all four countries were advantaged by the large percentages of their populations who could read and write. In both 1850 and 1914, the Scandinavian countries had the highest literacy rates in Europe, or in the world, and the Netherlands was well above the European average. This fact was of enormous value in helping the national economies find their niches in the evolving currents of the international economy.
Location was an important factor for all four countries. All had immediate access to the sea, and this had important implications for a significant international resource, fish, as well as for cheap transport, merchant marines, and the shipbuilding industry. Each took advantage of these opportunities in its own way. The people of the Netherlands, with a long tradition of fisheries and mercantile shipping, had difficulty in developing good harbors suitable for steamships: eventually they did so at Rotterdam and Amsterdam, with exceptional results for transit trade with Germany and central Europe and for the processing of overseas foodstuffs and raw materials (sugar, tobacco, chocolate, grain, and eventually oil). Denmark also had an admirable commercial history, particularly with respect to traffic through the Sound (the strait separating Denmark and Sweden). In 1857, in return for a payment of 63 million kronor from other commercial nations, Denmark abolished the Sound toll dues the fees it had collected since 1497 for the use of the Sound. This, along with other policy shifts toward free trade, resulted in a significant increase in traffic through the Sound and in the port of Copenhagen.
The political institutions of the four countries posed no significant barriers to industrialization or economic growth. The nineteenth century passed relatively peacefully for these countries, with progressive democratization taking place in all of them. They were reasonably well governed, without notable corruption or grandiose state projects, although in all of them the government gave some aid to railways, and in Sweden the state built the main lines. As small countries dependent on foreign markets, they followed a liberal trade policy in the main, though a protectionist movement developed in Sweden. In Denmark and Sweden agricultural reforms took place gradually from the late eighteenth century through the first half of the nineteenth, resulting in a new class of peasant landowners with a definite market orientation.
The key factor in the success of these countries (along with high literacy, which contributed to it) was their ability to adapt to the international division of labor determined by the early industrializers and to stake out areas of specialization in international markets for which they were especially well suited. This meant a great dependence on international commerce, which had notorious fluctuations; but it also meant high returns to those factors of production that were fortunate enough to be well placed in times of prosperity. In Sweden exports accounted for 18 percent of the national income in 1870, and in 1913, 22 percent of a much larger national income. In the early twentieth century, Denmark exported 63 percent of its agricultural production: butter, pork products, and eggs. It exported 80 percent of its butter, almost all to Great Britain, where it accounted for 40 percent of British butter imports.
R18P2
The mystery of yawningAccording to conventional theory, yawning takes place when people are bored or sleepy and serves the function of increasing alertness by reversing, through deeper breathing, the drop in blood oxygen levels that are caused by the shallow breathing that accompanies lack of sleep or boredom. Unfortunately, the few scientific investigations of yawning have failed to find any connection between how often someone yawns and how much sleep they have had or how tired they are. About the closest any research has come to supporting the tiredness theory is to confirm that adults yawn more often on weekdays than at weekends, and that school children yawn more frequently in their first year at primary school than they do in kindergarten.
Another flaw of the tiredness theory is that yawning does not raise alertness or physiological activity, as the theory would predict. When researchers measured the heart rate, muscle tension and skin conductance of people before, during and after yawning, they did detect some changes in skin conductance following yawning, indicating a slight increase in physiological activity. However, similar changes occurred when the subjects were asked simply to open their mouths or to breathe deeply. Yawning did nothing special to their state of physiological activity. Experiments have also cast serious doubt on the belief that yawning is triggered by a drop in blood oxygen or a rise in blood carbon dioxide. Volunteers were told to think about yawning while they breathed either normal air, pure oxygen, or an air mixture with an above-normal level of carbon dioxide. If the theory was correct, breathing air with extra carbon dioxide should have triggered yawning, while breathing pure oxygen should have suppressed yawning. In fact, neither condition made any difference to the frequency of yawning, which remained constant at about 24 yawns per hour. Another experiment demonstrated that physical exercise, which was sufficiently vigorous to double the rate of breathing, had no effect on the frequency of yawning. Again the implication is that yawning has little or nothing to do with oxygen.
A completely different theory holds that yawning assists in the physical development of the lungs early in life, but has no remaining biological function in adults. It has been suggested that yawning and hiccupping might serve to clear out the fetuses airways. The lungs of a fetus secrete a liquid that mixes with its mother's amniotic fluid. Babies with congenital blockages that prevent this fluid from escaping from their lungs are sometimes born with deformed lungs. It might be that yawning helps to clear out the lungs by periodically lowering the pressure in them. According to this theory, yawning in adults is just a developmental fossil with no biological function. But, while accepting that not everything in life can be explained by Darwinian evolution, there are sound reasons for being skeptical of theories like this one, which avoid the issue of what yawning does for adults. Yawning is distracting, consumes energy and takes time. It is almost certainly doing something significant in adults as well as in fetuses. What could it be?
The empirical evidence, such as it is, suggests an altogether different function for yawning—namely, that yawning prepares us for a change in activity level. Support for this theory came from a study of yawning behavior in everyday life. Volunteers wore wrist-mounted devices that automatically recorded their physical activity for up to two weeks: the volunteers also recorded their yawns by pressing a button on the device each time they yawned. The data showed that yawning tended to occur about 15 minutes before a period of increased behavioral activity. Yawning bore no relationship to sleep patterns, however. This accords with anecdotal evidence that people often yawn in situations where they are neither tired nor bored, but are preparing for impending mental and physical activity. Such yawning is often referred to as "incongruous" because it seems out of place, at least on the tiredness view: soldiers yawning before combat, musicians yawning before performing, and athletes yawning before competing. Their yawning seems to have nothing to do with sleepiness or boredom—quite the reverse—but it does precede a change in activity level.
R18P3
LightningLightning is a brilliant flash of light produced by an electrical discharge from a storm cloud. The electrical discharge takes place when the attractive tension between a region of negatively charged particles and a region of positively charged particles becomes so great that the charged particles suddenly rush together. The coming together of the oppositely charged particles neutralizes the electrical tension and releases a tremendous amount of energy, which we see as lightning. The separation of positively and negatively charged particles takes place during the development of the storm cloud.
The separation of charged particles that forms in a storm cloud has a sandwich-like structure. Concentrations of positively charged particles develop at the top and bottom of the cloud, but the middle region becomes negatively charged. Recent measurements made in the field together with laboratory simulations offer a promising explanation of how this structure of charged particles forms. What happens is that small (millimeter-to centimeter-size) pellets of ice form in the cold upper regions of the cloud. When these ice pellets fall, some of them strike much smaller ice crystals in the center of the cloud. The temperature at the center of the cloud is about -15℃ or lower. At such temperatures, the collision between the ice pellets and the ice crystals causes electrical charges to shift so that the ice pellets acquire a negative charge and the ice crystals become positively charged. Then updraft wind currents carry the light, positively charged ice crystals up to the top of the cloud. The heavier negatively charged ice pellets are left to concentrate in the center. This process explains why the top of the cloud becomes positively charged, while the center becomes negatively charged. The negatively charged region is large: several hundred meters thick and several kilometers in diameter. Below this large, cold, negatively charged region, the cloud is warmer than -15℃, and at these temperatures, collisions between ice crystals and falling ice pellets produce positively charged ice pellets that then populate a small region at the base of the cloud.
Most lightning takes place within a cloud when the charge separation within the cloud collapses. However, as the storm cloud develops, the ground beneath the cloud becomes positively charged and lightning can take place in the form of an electrical discharge between the negative charge of the cloud and the positively charged ground. Lightning that strikes the ground is the most likely to be destructive, so even though it represents only 20 percent of all lightning, it has received a lot of scientific attention.
Using high-speed photography, scientists have determined that there are two steps to the occurrence of lightning from a cloud to the ground. First, a channel, or path, is formed that connects the cloud and the ground. Then a strong current of electrons follows that path from the cloud to the ground, and it is that current that illuminates the channel as the lightning we see.
The formation of the channel is initiated when electrons surge from the cloud base toward the ground. When a stream of these negatively charged electrons comes within 100 meters of the ground it is met by a stream of positively charged particles that comes up from the ground. When the negatively and positively charged streams meet, a complete channel connecting the cloud and the ground is formed. The channel is only a few centimeters in diameter, but that is wide enough for electrons to follow the channel to the ground in the visible form of a flash of lightning. The stream of positive particles that meets the surge of electrons from the cloud often arises from a tall pointed structure such as a metal flagpole or a tower. That is why the subsequent lightning that follows the completed channel often strikes a tall structure.
Once a channel has been formed, it is usually used by several lightning discharges, each of them consisting of a stream of electrons from the cloud meeting a stream of positive particles along the established path. Sometimes, however, a stream of electrons following an established channel is met by a positive stream making a new path up from the ground. The result is a forked lightning that strikes the ground in two places.
R19P1
The Roman Army's Impact on BritainIn the wake of the Roman Empire's conquest of Britain in the first century A.D., a large number of troops stayed in the new province, and these troops had a considerable impact on Britain with their camps, fortifications, and participation in the local economy. Assessing the impact of the army on the civilian population starts from the realization that the soldiers were always unevenly distributed across the country. Areas rapidly incorporated into the empire were not long affected by the military. Where the army remained stationed, its presence was much more influential. The imposition of a military base involved the requisition of native lands for both the fort and the territory needed to feed and exercise the soldiers' animals. The imposition of military rule also robbed local leaders of opportunities to participate in local government, so social development was stunted and the seeds of disaffection sown. This then meant that the military had to remain to suppress rebellion and organize government.
Economic exchange was clearly very important as the Roman army brought with it very substantial spending power. Locally a fort had two kinds of impact. Its large population needed food and other supplies. Some of these were certainly brought from long distances, but demands were inevitably placed on the local area. Although goods could be requisitioned, they were usually paid for, and this probably stimulated changes in the local economy. When not campaigning, soldiers needed to be occupied; otherwise they represented a potentially dangerous source of friction and disloyalty. Hence a writing tablet dated 25 April tells of 343 men at one fort engaged on tasks like shoemaking, building a bathhouse, operating kilns, digging clay, and working lead. Such activities had a major effect on the local area, in particular with the construction of infrastructure such as roads, which improved access to remote areas.
Each soldier received his pay, but in regions without a developed economy there was initially little on which it could be spent. The pool of excess cash rapidly stimulated a thriving economy outside fort gates. Some of the demand for the services and goods was no doubt fulfilled by people drawn from far afield, but some local people certainly became entwined in this new economy. There was informal marriage with soldiers, who until AD 197 were not legally entitled to wed, and whole new communities grew up near the forts. These settlements acted like small towns, becoming centers for the artisan and trading populations.
The army also provided a mean of personal advancement for auxiliary soldiers recruited from the native peoples, as a man obtained hereditary Roman citizenship on retirement after service in an auxiliary regiment. Such units recruited on an ad hoc (as needed) basis from the area in which they were stationed, and there was evidently large-scale recruitment within Britain. The total numbers were at least 12,500 men up to the reign of the emperor Hadrian (A.D. 117-138), with a peak around A.D. 80. Although a small proportion of the total population, this perhaps had a massive local impact when a large proportion of the young men were removed from an area. Newly raised regiments were normally transferred to another province from whence it was unlikely that individual recruits would ever return. Most units raised in Britain went elsewhere on the European continent, although one is recorded in Morocco. The reverse process brought young men to Britain, where many continued to live after their 20 to 25 years of service, and this added to the cosmopolitan Roman character of the frontier population. By the later Roman period, frontier garrisons (groups of soldiers) were only rarely transferred, service in units became effectively hereditary, and forts were no longer populated or maintained at full strength.
This process of settling in as a community over several generations, combined with local recruitment, presumably accounts for the apparent stability of the British northern frontier in the later Roman period. It also explains why some of the forts continued in occupation long after Rome ceased to have any formal authority in Britain, at the beginning of the fifth century A.D. The circumstances that had allowed natives to become Romanized also led the self-sustaining military community of the frontier area to become effectively British.
R19P2
Succession Climax and EcosystemsIn the late nineteenth century, ecology began to grow into an independent science from its roots in natural history and plant geography. The emphasis of this new "community ecology" was on the composition and structure of communities consisting of different species. In the early twentieth century, the American ecologist Frederic Clements pointed out that a succession of plant communities would develop after a disturbance such as a volcanic eruption, heavy flood, or forest fire. An abandoned field, for instance, will be invaded successively by herbaceous plants (plants with little or no woody tissue), shrubs, and trees, eventually becoming a forest. Light-loving species are always among the first invaders, while shade-tolerant species appear later in the succession.
Clements and other early ecologists saw almost lawlike regularity in the order of succession, but that has not been substantiated. A general trend can be recognized, but the details are usually unpredictable. Succession is influenced by many factors: the nature of the soil, exposure to sun and wind, regularity of precipitation, chance colonizations, and many other random processes.
The final stage of a succession, called the climax by Clements and early ecologists, is likewise not predictable or of uniform composition. There is usually a good deal of turnover in species composition, even in a mature community. The nature of the climax is influenced by the same factors that influenced succession. Nevertheless, mature natural environments are usually in equilibrium. They change relatively little through time unless the environment itself changes.
For Clements, the climax was a "superorganism," an organic entity. Even some authors who accepted the climax concept rejected Clements' characterization of it as a superorganism, and it is indeed a misleading metaphor. An ant colony may be legitimately called a superorganism because its communication system is so highly organized that the colony always works as a whole and appropriately according to the circumstances. But there is no evidence for such an interacting communicative network in a climax plant formation. Many authors prefer the term "association" to the term "community" in order to stress the looseness of the interaction.
Even less fortunate was the extension of this type of thinking to include animals as well as plants. This resulted in the "biome," a combination of coexisting flora and fauna. Though it is true that many animals are strictly associated with certain plants, it is misleading to speak of a "spruce-moose biome," for example, because there is no internal cohesion to their association as in an organism. The spruce community is not substantially affected by either the presence or absence of moose. Indeed, there are vast areas of spruce forest without moose. The opposition to the Clementsian concept of plant ecology was initiated by Herbert Gleason, soon joined by various other ecologists. Their major point was that the distribution of a given species was controlled by the habitat requirements of that species and that therefore the vegetation types were a simple consequence of the ecologies of individual plant species.
With "climax," "biome," "superorganism," and various other technical terms for the association of animals and plants at a given locality being criticized, the term "ecosystem" was more and more widely adopted for the whole system of associated organisms together with the physical factors of their environment. Eventually, the energy-transforming role of such a system was emphasized. Ecosystems thus involve the circulation, transformation, and accumulation of energy and matter through the medium of living things and their activities. The ecologist is concerned primarily with the quantities of matter and energy that pass through a given ecosystem, and with the rates at which they do so.
Although the ecosystem concept was very popular in the 1950s and 1960s, it is no longer the dominant paradigm. Gleason's arguments against climax and biome are largely valid against ecosystems as well. Furthermore, the number of interactions is so great that they are difficult to analyze, even with the help of large computers. Finally, younger ecologists have found ecological problems involving behavior and life-history adaptations more attractive than measuring physical constants. Nevertheless, one still speaks of the ecosystem when referring to a local association of animals and plants, usually without paying much attention to the energy aspects.
R19P3
Discovering the Ice AgesIn the middle of the nineteenth century, Louis Agassiz, one of the first scientists to study glaciers, immigrated to the United States from Switzerland and became a professor at Harvard University, where he continued his studies in geology and other sciences. For his research, Agassiz visited many places in the northern parts of Europe and North America, from the mountains of Scandinavia and New England to the rolling hills of the American Midwest. In all these diverse regions, Agassiz saw signs of glacial erosion and sedimentation. In flat plains country, he saw moraines (accumulations of earth and loose rock that form at the edges of glaciers) that reminded him of the terminal moraines found at the end of valley glaciers in the Alps. The heterogeneous material of the drift (sand, clay, and rocks deposited there) convinced him of its glacial origin.
The areas covered by this material were so vast that the ice that deposited it must have been a continental glacier larger than Greenland or Antarctica. Eventually, Agassiz and others convinced geologists and the general public that a great continental glaciation had extended the polar ice caps far into regions that now enjoy temperate climates. For the first time, people began to talk about ice ages. It was also apparent that the glaciation occurred in the relatively recent past because the drift was soft, like freshly deposited sediment. We now know the age of the glaciation accurately from radiometric dating of the carbon-14 in logs buried in the drift. The drift of the last glaciation was deposited during one of the most recent epochs of geologic time, the Pleistocene, which lasted from 1.8 million to 10,000 years ago. Along the east coast of the United States, the southernmost advance of this ice is recorded by the enormous sand and drift deposits of the terminal moraines that form Long Island and Cape Cod.
It soon became clear that there were multiple glacial ages during the Pleistocene, with warmer interglacial intervals between them. As geologists mapped glacial deposits in the late nineteenth century, they became aware that there were several layers of drift, the lower ones corresponding to earlier ice ages. Between the older layers of glacial material were well-developed soils containing fossils of warm-climate plants. These soils were evidence that the glaciers retreated as the climate warmed. By the early part of the twentieth century, scientists believed that four distinct glaciations had affected North America and Europe during the Pleistocene epoch.
This idea was modified in the late twentieth century, when geologists and oceanographers examining oceanic sediment found fossil evidence of warming and cooling of the oceans. Ocean sediments presented a much more complete geologic record of the Pleistocene than continental glacial deposits did. The fossils buried in Pleistocene and earlier ocean sediments were of foraminifera—small, single-celled marine organisms that secrete shells of calcium carbonate, or calcite. These shells differ in their proportion of ordinary oxygen (oxygen-16) and the heavy oxygen isotope (oxygen-18). The ratio of oxygen-16 to oxygen-18 found in the calcite of a foraminifer's shell depends on the temperature of the water in which the organism lived. Different ratios in the shells preserved in various layers of sediment reveal the temperature changes in the oceans during the Pleistocene epoch.
Isotopic analysis of shells allowed geologists to measure another glacial effect. They could trace the growth and shrinkage of continental glaciers, even in parts of the ocean where there may have been no great change in temperature—around the equator, for example. The oxygen isotope ratio of the ocean changes as a great deal of water is withdrawn from it by evaporation and is precipitated as snow to form glacial ice. During glaciations, the lighter oxygen-16 has a greater tendency to evaporate from the ocean surface than the heavier oxygen-18 does. Thus, more of the heavy isotope is left behind in the ocean and absorbed by marine organisms. From this analysis of marine sediments, geologists have learned that there were many shorter, more regular cycles of glaciation and deglaciation than geologists had recognized from the glacial drift of the continents alone.
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Westward MigrationThe story of the westward movement of population in the United States is, in the main, the story of the expansion of American agriculture—of the development of new areas for the raising of livestock and the cultivation of wheat, corn, tobacco, and cotton. After 1815 improved transportation enabled more and more western farmers to escape a self-sufficient way of life and enter a national market economy. During periods when commodity prices were high, the rate of westward migration increased spectacularly. "Old America seemed to be breaking up and moving westward," observed an English visitor in 1817,during the first great wave of migration. Emigration to the West reached a peak in the 1830's. Whereas in 1810 only a seventh of the American people lived west of the Appalachian Mountains, by 1840 more than a third lived there.
Why were these hundreds of thousands of settlers—most of them farmers, some of them artisans—drawn away from the cleared fields and established cities and villages of the East? Certain characteristics of American society help to explain this remarkable migration. The European ancestors of some Americans had for centuries lived rooted to the same village or piece of land until some religious, political, or economic crisis uprooted them and drove them across the Atlantic. Many of those who experienced this sharp break thereafter lacked the ties that had bound them and their ancestors to a single place. Moreover, European society was relatively stratified; occupation and social status were inherited. In American society, however, the class structure was less rigid; some people changed occupations easily and believed it was their duty to improve their social and economic position. As a result, many Americans were an inveterately restless, rootless, and ambitious people. Therefore, these social traits helped to produce the nomadic and daring settlers who kept pushing westward beyond the fringes of settlement. In addition, there were other immigrants who migrated west in search of new homes, material success, and better lives.
The West had plenty of attractions: the alluvial river bottoms, the fecund soils of the rolling forest lands, the black loams of the prairies were tempting to New England farmers working their rocky, sterile land and to southeastern farmers plagued with soil depletion and erosion. In 1820 under a new land law, a farm could be bought for $100. The continued proliferation of banks made it easier for those without cash to negotiate loans in paper money. Western Farmers borrowed with the confident expectation that the expanding economy would keep farm prices high, thus making it easy to repay loans when they fell due.
Transportation was becoming less of a problem for those who wished to move west and for those who hand farm surpluses to send to market. Prior to 1815, western farmers who did not live on navigable waterways were connected to them only by dirt roads and mountain trails. Livestock could be driven across the mountains, but the cost of transporting bulky grains in this fashion was several times greater than their value in eastern markets. The first step toward an improvement of western transportation was the construction of turnpikes. These roads made possible a reduction in transportation costs and thus stimulated the commercialization of agriculture along their routes.
Two other developments presaged the end of the era of turnpikes and started a transportation revolution that resulted in increased regional specialization and the growth of a national market economy. First came the steamboat; although flatboats and keelboats continued to be important until the 1850’s steamboats eventually superseded all other craft in the carrying of passengers and freight. Steamboats were not only faster but also transported upriver freight for about one tenth of what it had previously cost on hand-propelled keelboats. Next came the Erie Canal, an enormous project in its day, spanning about 350 miles. After the canal went into operation, the cost per mile of transporting a ton of freight from Buffalo to New York City declined from nearly 20 cents to less than 1 cent. Eventually, the western states diverted much of their produce from the rivers to the Erie Canal, a shorter route to eastern markets.
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Early Settlements in the Southwest AsiaThe universal global warming at the end of the Ice Age had dramatic effects on temperate regions of Asia, Europe, and North America. Ice sheets retreated and sea levels rose. The climatic changes in southwestern Asia were more subtle, in that they involved shifts in mountain snow lines, rainfall patterns, and vegetation cover. However, these same cycles of change had momentous impacts on the sparse human populations of the region. At the end of the Ice Age, no more than a few thousand foragers lived along the eastern Mediterranean coast, in the Jordan and Euphrates valleys. Within 2,000 years, the human population of the region numbered in the tens of thousands, all as a result of village life and farming. Thanks to new environmental and archaeological discoveries, we now know something about this remarkable change in local life.
Pollen samples from freshwater lakes in Syria and elsewhere tell us forest cover expanded rapidly at the end of the Ice Age, for the southwestern Asian climate was still cooler and considerably wetter than today. Many areas were richer in animal and plant species than they are now, making them highly favorable for human occupation. About 9000 B.C., most human settlements lay in the area along the Mediterranean coast and in the Zagros Mountains of Iran and their foothills. Some local areas, like the Jordan River valley, the middle Euphrates valley, and some Zagros valleys, were more densely populated than elsewhere. Here more sedentary and more complex societies flourished. These people exploited the landscape intensively, foraging on hill slopes for wild cereal grasses and nuts, while hunting gazelle and other game on grassy lowlands and in river valleys. Their settlements contain exotic objects such as seashells, stone bowls, and artifacts made of obsidian (volcanic glass), all traded from afar. This considerable volume of intercommunity exchange brought a degree of social complexity in its wake.
Thanks to extremely fine-grained excavation and extensive use of flotation methods (through which seeds are recovered from soil samples), we know a great deal about the foraging practices of the inhabitants of Abu Hureyra in Syria's Euphrates valley. Abu Hureyra was founded about 9500B.C, a small village settlement of cramped pit dwellings (houses dug partially in the soil) with reed roofs supported by wooden uprights. For the next 1,500 years, its inhabitants enjoyed a somewhat warmer and damper climate than today, living in a well-wooded steppe area where wild cereal grasses were abundant. They subsisted off spring migrations of Persian gazelles from the south. With such a favorable location, about 300 to 400 people lived in a sizable, permanent settlement. They were no longer a series of small bands but lived in a large community with more elaborate social organization, probably grouped into clans of people of common descent.
The flotation samples from the excavations allowed botanists to study shifts in plant-collecting habits as if they were looking through a telescope at a changing landscape. Hundreds of tiny plant remains show how the inhabitants exploited nut harvests in nearby pistachio and oak forests. However, as the climate dried up, the forests retreated from the vicinity of the settlement. The inhabitants turned to wild cereal grasses instead, collecting them by the thousands, while the percentage of nuts in the diet fell. By 8200B.C., drought conditions were so severe that the people abandoned their long-established settlement, perhaps dispersing into smaller camps.
Five centuries later, about 7700B.C., a new village rose on the mound. At first the inhabitants still hunted gazelle intensively. Then, about 7000 B.C., within the space of a few generations, they switched abruptly to herding domesticated goats and sheep and to growing einkorn, pulses, and other cereal grasses. Abu Hureyra grew rapidly until it covered nearly 30 acres. It was a close-knit community of rectangular, one-story mud-brick houses, joined by narrow lanes and courtyards, finally abandoned about 5000 B.C.. Many complex factors led to the adoption of the new economies, not only at Abu Hureyra, but at many other locations such as 'Ain Ghazal, also in Syria, where goat toe bones showing the telltale marks of abrasion caused by foot tethering (binding) testify to early herding of domestic stock.
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Fossil PreservationWhen one considers the many ways by which organisms are completely destroyed after death, it is remarkable that fossils are as common as they are. Attack by scavengers and bacteria, chemical decay, and destruction by erosion and other geologic agencies make the odds against preservation very high. However, the chances of escaping complete destruction are vastly improved if the organism happens to have a mineralized skeleton and dies in a place where it can be quickly buried by sediment. Both of these conditions are often found on the ocean floors, where shelled invertebrates (organisms without spines) flourish and are covered by the continuous rain of sedimentary particles. Although most fossils are found in marine sedimentary rocks, they also are found in terrestrial deposits left by streams and lakes. On occasion, animals and plants have been preserved after becoming immersed in tar or quicksand, trapped in ice or lava flows, or engulfed by rapid falls of volcanic ash.
The term "fossil" often implies petrifaction, literally a transformation into stone. After the death of an organism, the soft tissue is ordinarily consumed by scavengers and bacteria. The empty shell of a snail or clam may be left behind, and if it is sufficiently durable and resistant to dissolution, it may remain basically unchanged for a long period of time. Indeed, unaltered shells of marine invertebrates are known from deposits over 100 million years old. In many marine creatures, however, the skeleton is composed of a mineral variety of calcium carbonate called aragonite. Although aragonite has the same composition as the more familiar mineral known as calcite, it has a different crystal form, is relatively unstable, and in time changes to the more stable calcite.
Many other processes may alter the shell of a clam or snail and enhance its chances for preservation. Water containing dissolved silica, calcium carbonate, or iron may circulate through the enclosing sediment and be deposited in cavities such as marrow cavities and canals in bone once occupied by blood vessels and nerves. In such cases, the original composition of the bone or shell remains, but the fossil is made harder and more durable. This addition of a chemically precipitated substance into pore spaces is termed "permineralization."
Petrifaction may also involve a simultaneous exchange of the original substance of a dead plant or animal with mineral matter of a different composition. This process is termed " replacement" because solutions have dissolved the original material and replaced it with an equal volume of the new substance. Replacement can be a marvelously precise process, so that details of shell ornamentation, tree rings in wood, and delicate structures in bone are accurately preserved.
Another type of fossilization, known as carbonization, occurs when soft tissues are preserved as thin films of carbon. Leaves and tissue of soft-bodied organisms such as jellyfish or worms may accumulate, become buried and compressed, and lose their volatile constituents. The carbon often remains behind as a blackened silhouette.
Although it is certainly true that the possession of hard parts enhances the prospect of preservation, organisms having soft tissues and organs are also occasionally preserved. Insects and even small invertebrates have been found preserved in the hardened resins of conifers and certain other trees. X-ray examination of thin slabs of rock sometimes reveals the ghostly outlines of tentacles, digestive tracts, and visual organs of a variety of marine creatures. Soft parts, including skin, hair, and viscera of ice age mammoths, have been preserved in frozen soil or in the oozing tar of oil seeps.
The probability that actual remains of soft tissue will be preserved is improved if the organism dies in an environment of rapid deposition and oxygen deprivation. Under such conditions, the destructive effects of bacteria are diminished. The Middle Eocene Messel Shale (from about 48 million years ago) of Germany accumulated in such an environment. The shale was deposited in an oxygen-deficient lake where lethal gases sometimes bubbled up and killed animals. Their remains accumulated on the floor of the lake and were then covered by clay and silt. Among the superbly preserved Messel fossils are insects with iridescent exoskeletons (hard outer coverings), frogs with skin and blood vessels intact, and even entire small mammals with preserved fur and soft tissue.
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Geothermal EnergyEarth's internal heat, fueled by radioactivity, provides the energy for plate tectonics and continental drift, mountain building, and earthquakes. It can also be harnessed to drive electric generators and heat homes. Geothermal energy becomes available in a practical form when underground heat is transferred by water that is heated as it passes through a subsurface region of hot rocks (a heat reservoir) that may be hundreds or thousands of feet deep. The water is usually naturally occurring groundwater that seeps down along fractures in the rock; less typically, the water is artificially introduced by being pumped down from the surface. The water is brought to the surface, as a liquid or steam, through holes drilled for the purpose.
By far the most abundant form of geothermal energy occurs at the relatively low temperatures of 80° to 180° centigrade. Water circulated through heat reservoirs in this temperature range is able to extract enough heat to warm residential, commercial, and industrial spaces. More than 20,000 apartments in France are now heated by warm underground water drawn from a heat reservoir in a geologic structure near Paris called the Paris Basin. Iceland sits on a volcanic structure known as the Mid-Atlantic Ridge. Reykjavik, the capital of Iceland, is entirely heated by geothermal energy derived from volcanic heat.
Geothermal reservoirs with temperatures above 180° centigrade are useful for generating electricity. They occur primarily in regions of recent volcanic activity as hot, dry rock; natural hot water; or natural steam. The latter two sources are limited to those few areas where surface water seeps down through underground faults or fractures to reach deep rocks heated by the recent activity of molten rock material. The world's largest supply of natural steam occurs at The Geysers, 120 kilometers north of San Francisco, California. In the 1990s enough electricity to meet about half the needs of San Francisco was being generated there. This facility was then in its third decade of production and was beginning to show signs of decline, perhaps because of over development. By the late 1990s some 70 geothermal electric-generating plants were in operation in California, Utah, Nevada, and Hawaii, generating enough power to supply about a million people. Eighteen countries now generate electricity using geothermal heat.
Extracting heat from very hot, dry rocks presents a more difficult problem: the rocks must be fractured to permit the circulation of water, and the water must be provided artificially. The rocks are fractured by water pumped down at very high pressures. Experiments are under way to develop technologies for exploiting this resource.
Like most other energy sources, geothermal energy presents some environmental problems. The surface of the ground can sink if hot groundwater is withdrawn without being replaced. In addition, water heated geothermally can contain salts and toxic materials dissolved from the hot rock. These waters present a disposal problem if they are not returned to the ground from which they were removed.
The contribution of geothermal energy to the world's energy future is difficult to estimate. Geothermal energy is in a sense not renewable, because in most cases the heat would be drawn out of a reservoir much more rapidly than it would be replaced by the very slow geological processes by which heat flows through solid rock into a heat reservoir. However, in many places (for example, California, Hawaii, the Philippines, Japan, Mexico, the rift valleys of Africa)the resource is potentially so large that its future will depend on the economics of production. At present, we can make efficient use of only naturally occurring hot water or steam deposits. Although the potential is enormous, it is likely that in the near future geothermal energy can make important local contributions only where the resource is close to the user and the economics are favorable, as they are in California, New Zealand, and Iceland. Geothermal energy probably will not make large-scale contributions to the world energy budget until well into the twenty-first century, if ever.
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The Origins of AgricultureHow did it come about that farming developed independently in a number of world centers (the Southeast Asian mainland, Southwest Asia, Central America, lowland and highland South America, and equatorial Africa) at more or less the same time? Agriculture developed slowly among populations that had an extensive knowledge of plants and animals. Changing from hunting and gathering to agriculture had no immediate advantages. To start with, it forced the population to abandon the nomad's life and become sedentary, to develop methods of storage and, often, systems of irrigation. While hunter-gatherers always had the option of moving elsewhere when the resources were exhausted, this became more difficult with farming. Furthermore, as the archaeological record shows, the state of health of agriculturalists was worse than that of their contemporary hunter-gatherers.
Traditionally, it was believed that the transition to agriculture was the result of a worldwide population crisis. It was argued that once hunter-gatherers had occupied the whole world, the population started to grow everywhere and food became scarce; agriculture would have been a solution to this problem. We know, however, that contemporary hunter-gatherer societies control their population in a variety of ways. The idea of a world population crisis is therefore unlikely, although population pressure might have arisen in some areas.
Climatic changes at the end of the glacial period 13,000 years ago have been proposed to account for the emergence of farming. The temperature increased dramatically in a short period of time (years rather than centuries), allowing for a growth of the hunting-gathering population due to the abundance of resources. There were, however, fluctuations in the climatic conditions, with the consequences that wet conditions were followed by dry ones, so that the availability of plants and animals oscillated brusquely.
It would appear that the instability of the climatic conditions led populations that had originally been nomadic to settle down and develop a sedentary style of life, which led in turn to population growth and to the need to increase the amount of food available. Farming originated in these conditions. Later on, it became very difficult to change because of the significant expansion of these populations. It could be argued, however, that these conditions are not sufficient to explain the origins of agriculture. Earth had experienced previous periods of climatic change, and yet agriculture had not been developed.
It is archaeologist Steven Mithen's thesis, brilliantly developed in his book The Prehistory of the Mind (1996), that approximately 40,000 years ago the human mind developed cognitive fluidity, that is, the integration of the specializations of the mind: technical, natural history (geared to understanding the behavior and distribution of natural resources), social intelligence, and the linguistic capacity. Cognitive fluidity explains the appearance of art, religion, and sophisticated speech. Once humans possessed such a mind, they were able to find an imaginative solution to a situation of severe economic crisis such as the farming dilemma described earlier. Mithen proposes the existence of four mental elements to account for the emergence of farming: (1) the ability to develop tools that could be used intensively to harvest and process plant resources; (2) the tendency to use plants and animals as the medium to acquire social prestige and power; (3) the tendency to develop "social relationships" with animals structurally similar to those developed with people—specifically, the ability to think of animals as people (anthropomorphism) and of people as animals (totemism); and (4) the tendency to manipulate plants and animals.
The fact that some societies domesticated animals and plants, discovered the use of metal tools, became literate, and developed a state should not make us forget that others developed pastoralism or horticulture (vegetable gardening) but remained illiterate and at low levels of productivity; a few entered the modern period as hunting and gathering societies. It is anthropologically important to inquire into the conditions that made some societies adopt agriculture while others remained hunter-gatherers or horticulturalists. However, it should be kept in mind that many societies that knew of agriculture more or less consciously avoided it. Whether Mithen's explanation is satisfactory is open to contention, and some authors have recently emphasized the importance of other factors.
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Autobiographical MemoryThink back to your childhood and try to identify your earliest memory. How old were you? Most people are not able to recount memories for experiences prior to the age of three years, a phenomenon called infantile amnesia. The question of why infantile amnesia occurs has intrigued psychologists for decades, especially in light of ample evidence that infants and young children can display impressive memory capabilities. Many find that understanding the general nature of autobiographical memory, that is, memory for events that have occurred in one's own life, can provide some important clues to this mystery. Between ages three and four, children begin to give fairly lengthy and cohesive descriptions of events in their past. What factors are responsible for this developmental turning point?
Perhaps the explanation goes back to some ideas raised by influential Swiss psychologist Jean Piaget—namely, that children under age two years represent events in a qualitatively different form than older children do. According to this line of thought, the verbal abilities that blossom in the two year old allow events to be coded in a form radically different from the action-based codes of the infant. Verbal abilities of one year olds are, in fact, related to their memories for events one year later. When researchers had one year olds imitate an action sequence one year after they first saw it, there was correlation between the children's verbal skills at the time they first saw the event and their success on the later memory task. However, even children with low verbal skills showed evidence of remembering the event; thus, memories may be facilitated by but are not dependent on those verbal skills.
Another suggestion is that before children can talk about past events in their lives, they need to have a reasonable understanding of the self as a psychological entity. The development of an understanding of the self becomes evident between the first and second years of life and shows rapid elaboration in subsequent years. The realization that the physical self has continuity in time, according to this hypothesis, lays the foundation for the emergence of autobiographical memory.
A third possibility is that children will not be able to tell their own "life story" until they understand something about the general form stories take, that is, the structure of narratives. Knowledge about narratives arises from social interactions, particularly the storytelling that children experience from parents and the attempts parents make to talk with children about past events in their lives. When parents talk with children about "what we did today" or "last week" or "last year," they guide the children's formation of a framework for talking about the past. They also provide children with reminders about the memory and relay the message that memories are valued as part of the cultural experience. It is interesting to note that some studies show Caucasian American children have earlier childhood memories than Korean children do. Furthermore, other studies show that Caucasian American mother-child pairs talk about past events three times more often than do Korean mother-child pairs. Thus, the types of social experiences children have do factor into the development of autobiographical memories.
A final suggestion is that children must begin to develop a "theory of mind"—an awareness of the concept of mental states (feelings, desires, beliefs, and thoughts), their own and those of others—before they can talk about their own past memories. Once children become capable of answering such questions as "What does it mean to remember?" and "What does it mean to know something?" improvements in memory seem to occur.
It may be that the developments just described are intertwined with and influence one another. Talking with parents about the past may enhance the development of the self-concept, for example, as well as help the child understand what it means to "remember." No doubt the ability to talk about one's past represents memory of a different level of complexity than simple recognition or recall.
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SpartinaSpartina alterniflora, known as cordgrass, is a deciduous, perennial flowering plant native to the Atlantic coast and the Gulf Coast of the United States. It is the dominant native species of the lower salt marshes along these coasts, where it grows in the intertidal zone (the area covered by water some parts of the day and exposed others).
These natural salt marshes are among the most productive habitats in the marine environment. Nutrient-rich water is brought to the wetlands during each high tide, making a high rate of food production possible. As the seaweed and marsh grass leaves die, bacteria break down the plant material, and insects, small shrimplike organisms, fiddler crabs, and marsh snails eat the decaying plant tissue, digest it, and excrete wastes high in nutrients. Numerous insects occupy the marsh, feeding on living or dead cordgrass tissue, and redwing blackbirds, sparrows, rodents, rabbits, and deer feed directly on the cordgrass. Each tidal cycle carries plant material into the offshore water to be used by the subtidal organisms.
Spartina is an exceedingly competitive plant. It spreads primarily by underground stems; colonies form when pieces of the root system or whole plants float into an area and take root or when seeds float into a suitable area and germinate. Spartina establishes itself on substrates ranging from sand and silt to gravel and cobble and is tolerant of salinities ranging from that of near freshwater (0.05 percent) to that of salt water (3.5 percent). Because they lack oxygen, marsh sediments are high in sulfides that are toxic to most plants. Spartina has the ability to take up sulfides and convert them to sulfate, a form of sulfur that the plant can use; this ability makes it easier for the grass to colonize marsh environments. Another adaptive advantage is Spartina’s ability to use carbon dioxide more efficiently than most other plants.
These characteristics make Spartina a valuable component of the estuaries where it occurs naturally. The plant functions as a stabilizer and a sediment trap and as a nursery area for estuarine fish and shellfish. Once established, a stand of Spartina begins to trap sediment, changing the substrate elevation, and eventually the stand evolves into a high marsh system where Spartina is gradually displaced by higher-elevation, brackish-water species. As elevation increases, narrow, deep channels of water form throughout the marsh. Along the east coast Spartina is considered valuable for its ability to prevent erosion and marshland deterioration; it is also used for coastal restoration projects and the creation of new wetland sites.
Spartina was transported to Washington State in packing materials for oysters transplanted from the east coast in 1894. Leaving its insect predators behind, the cordgrass has been spreading slowly and steadily along Washington’s tidal estuaries on the west coast, crowding out the native plants and drastically altering the landscape by trapping sediment. Spartina modifies tidal mudflats, turning them into high marshes inhospitable to the many fish and waterfowl that depend on the mudflats. It is already hampering the oyster harvest and the Dungeness crab fishery, and it interferes with the recreational use of beaches and waterfronts. Spartina has been transplanted to England and to New Zealand for land reclamation and shoreline stabilization. In New Zealand the plant has spread rapidly, changing mudflats with marshy fringes to extensive salt meadows and reducing the number and kinds of birds and animals that use the marsh.
Efforts to control Spartina outside its natural environment have included burning, flooding, shading plants with black canvas or plastic, smothering the plants with dredged materials or clay, applying herbicide, and mowing repeatedly. Little success has been reported in New Zealand and England; Washington State’s management program has tried many of these methods and is presently using the herbicide glyphosphate to control its spread. Work has begun to determine the feasibility of using insects as biological controls, but effective biological controls are considered years away. Even with a massive effort, it is doubtful that complete eradication of Spartina from nonnative habitats is possible, for it has become an integral part of these shorelines and estuaries during the last 100 to 200 years.
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The Birth of PhotographyPerceptions of the visible world were greatly altered by the invention of photography in the middle of the nineteenth century. In particular, and quite logically, the art of painting was forever changed, though not always in the ways one might have expected. The realistic and naturalistic painters of the mid- and late-nineteenth century were all intently aware of photography—as a thing to use, to learn from, and react to.
Unlike most major inventions, photography had been long and impatiently awaited. The images produced by the camera obscura, a boxlike device that used a pinhole or lens to throw an image onto a ground-glass screen or a piece of white paper, were already familiar—the device had been much employed by topographical artists like the Italian painter Canaletto in his detailed views of the city of Venice. What was lacking was a way of giving such images permanent form. This was finally achieved by Louis Daguerre (1787-1851), who perfected a way of fixing them on a silvered copper plate. His discovery, the "daguerreotype," was announced in 1839.
A second and very different process was patented by the British inventor William Henry Talbot (1800-1877) in 1841. Talbot's "calotype" was the first negative-to-positive process and the direct ancestor of the modern photograph. The calotype was revolutionary in its use of chemically treated paper in which areas hit by light became dark in tone, producing a negative image. This "negative," as Talbot called it, could then be used to print multiple positive images on another piece of treated paper.
The two processes produced very different results. The daguerreotype was a unique image that reproduced what was in front of the camera lens in minute, unselective detail and could not be duplicated. The calotype could be made in series, and was thus the equivalent of an etching or an engraving. Its general effect was soft edged and tonal.
One of the things that most impressed the original audience for photography was the idea of authenticity. Nature now seemed able to speak for itself, with a minimum of interference. The title Talbot chose for his book, The Pencil of Nature (the first part of which was published in 1844), reflected this feeling. Artists were fascinated by photography because it offered a way of examining the world in much greater detail. They were also afraid of it, because it seemed likely to make their own efforts unnecessary.
Photography did indeed make certain kinds of painting obsolete—the daguerreotype virtually did away with the portrait miniature. It also made the whole business of making and owning images democratic. Portraiture, once a luxury for the privileged few, was suddenly well within the reach of many more people.
In the long term, photography's impact on the visual arts was far from simple. Because the medium was so prolific, in the sense that it was possible to produce a multitude of images very cheaply, it was soon treated as the poor relation of fine art, rather than its destined successor. Even those artists who were most dependent on photography became reluctant to admit that they made use of it, in case this compromised their professional standing.
The rapid technical development of photography—the introduction of lighter and simpler equipment, and of new emulsions that coated photographic plates, film, and paper and enabled images to be made at much faster speeds—had some unanticipated consequences. Scientific experiments made by photographers such as Eadweard Muybridge (1830-1904) and Etienne-Jules Marey (1830-1904) demonstrated that the movements of both humans and animals differed widely from the way they had been traditionally represented in art. Artists, often reluctantly, were forced to accept the evidence provided by the camera. The new candid photography—unposed pictures that were made when the subjects were unaware that their pictures were being taken—confirmed these scientific results, and at the same time, thanks to the radical cropping (trimming) of images that the camera often imposed, suggested new compositional formats. The accidental effects obtained by candid photographers were soon being copied by artists such as the French painter Degas.
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The Allende MeteoriteSometime after midnight on February 8,1969, a large, bright meteor entered Earth's atmosphere and broke into thousands of pieces, plummeted to the ground, and scattered over an area 50 miles long and 10 miles wide in the state of Chihuahua in Mexico. The first meteorite from this fall was found in the village of Pueblito de Allende. Altogether, roughly two tons of meteorite fragments were recovered, all of which bear the name Allende for the location of the first discovery.
Individual specimens of Allende are covered with a black, glassy crust that formed when their exteriors melted as they were slowed by Earth's atmosphere. When broken open, Allende stones are revealed to contain an assortment of small, distinctive objects, spherical or irregular in shape and embedded in a dark gray matrix (binding material), which were once constituents of the solar nebula—the interstellar cloud of gas and dust out of which our solar system was formed.
The Allende meteorite is classified as a chondrite. Chondrites take their name from the Greek word chondros—meaning "seed"—an allusion to their appearance as rocks containing tiny seeds. These seeds are actually chondrules: millimeter-sized melted droplets of silicate material that were cooled into spheres of glass and crystal. A few chondrules contain grains that survived the melting event, so these enigmatic chondrules must have formed when compact masses of nebular dust were fused at high temperatures—approaching 1,700 degrees Celsius—and then cooled before these surviving grains could melt. Study of the textures of chondrules confirms that they cooled rather quickly, in times measured in minutes or hours, so the heating events that formed them must have been localized. It seems very unlikely that large portions of the nebula were heated to such extreme temperatures, and huge nebula areas could not possibly have lost heat so fast. Chondrules must have been melted in small pockets of the nebula that were able to lose heat rapidly. The origin of these peculiar glassy spheres remains an enigma.
Equally perplexing constituents of Allende are the refractory inclusions: irregular white masses that tend to be larger than chondrules. They are composed of minerals uncommon on Earth, all rich in calcium, aluminum, and titanium, the most refractory (resistant to melting) of the major elements in the nebula. The same minerals that occur in refractory inclusions are believed to be the earliest-formed substances to have condensed out of the solar nebula. However, studies of the textures of inclusions reveal that the order in which the minerals appeared in the inclusions varies from inclusion to inclusion, and often does not match the theoretical condensation sequence for those metals.
Chondrules and inclusions in Allende are held together by the chondrite matrix, a mixture of fine-grained, mostly silicate minerals that also includes grains of iron metal and iron sulfide. At one time it was thought that these matrix grains might be pristine nebular dust, the sort of stuff from which chondrules and inclusions were made. However, detailed studies of the chondrite matrix suggest that much of it, too, has been formed by condensation or melting in the nebula, although minute amounts of surviving interstellar dust are mixed with the processed materials.
All these diverse constituents are aggregated together to form chondritic meteorites, like Allende, that have chemical compositions much like that of the Sun. To compare the compositions of a meteorite and the Sun, it is necessary that we use ratios of elements rather than simply the abundances of atoms. After all, the Sun has many more atoms of any element, say iron, than does a meteorite specimen, but the ratios of iron to silicon in the two kinds of matter might be comparable. The compositional similarity is striking. The major difference is that Allende is depleted in the most volatile elements, like hydrogen, carbon, oxygen, nitrogen, and the noble gases, relative to the Sun. These are the elements that tend to form gases even at very low temperatures. We might think of chondrites as samples of distilled Sun, a sort of solar sludge from which only gases have been removed. Since practically all the solar system's mass resides in the Sun, this similarity in chemistry means that chondrites have average solar system composition, except for the most volatile elements; they are truly lumps of nebular matter, probably similar in composition to the matter from which planets were assembled.
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Urban ClimatesThe city is an extraordinary processor of mass and energy and has its own metabolism. A daily input of water, food, and energy of various kinds is matched by an output of sewage, solid waste, air pollutants, energy, and materials that have been transformed in some way. The quantities involved are enormous. Many aspects of this energy use affect the atmosphere of a city, particularly in the production of heat.
In winter the heat produced by a city can equal or surpass the amount of heat available from the Sun. All the heat that warms a building eventually transfers to the surrounding air, a process that is quickest where houses are poorly insulated. But an automobile produces enough heat to warm an average house in winter, and if a house were perfectly insulated, one adult could also produce more than enough heat to warm it. Therefore, even without any industrial production of heat, an urban area tends to be warmer than the countryside that surrounds it.
The burning of fuel, such as by cars, is not the only source of this increased heat. Two other factors contribute to the higher overall temperature in cities. The first is the heat capacity of the materials that constitute the city, which is typically dominated by concrete and asphalt. During the day, heat from the Sun can be conducted into these materials and stored—to be released at night. But in the countryside materials have a significantly lower heat capacity because a vegetative blanket prevents heat from easily flowing into and out of the ground. The second factor is that radiant heat coming into the city from the Sun is trapped in two ways: (1) by a continuing series of reflection among the numerous vertical surfaces that buildings present and (2) by the dust dome, the cloudlike layer of polluted air that most cities produce. Shortwave radiation from the Sun passes through the pollution dome more easily than outgoing longwave radiation does; the latter is absorbed by the gaseous pollutants of the dome and reradiated back to the urban surface.
Cities, then, are warmer than the surrounding rural areas, and together they produce a phenomenon known as the urban heat island. Heat islands develop best under particular conditions associated with light winds, but they can form almost any time. The precise configuration of a heat island depends on several factors. For example, the wind can make a heat island stretch in the direction it blows. When a heat island is well developed, variations can be extreme; in winter, busy streets in cities can be 1.7℃ warmer than the side streets. Areas near traffic lights can be similarly warmer than the areas between them because of the effect of cars standing in traffic instead of moving. The maximum differences in temperature between neighboring urban and rural environments is called the heat-island intensity for that region. In general, the larger the city, the greater its heat-island intensity. The actual level of intensity depends on such factors as the physical layout, population density, and productive activities of a metropolis.
The surface-atmosphere relationships inside metropolitan areas produce a number of climatic peculiarities. For one thing, the presence or absence of moisture is affected by the special qualities of the urban surface. With much of the built-up landscape impenetrable by water, even gentle rain runs off almost immediately from rooftops, streets, and parking lots. Thus, city surfaces, as well as the air above them, tend to be drier between episodes of rain; with little water available for the cooling process of evaporation, relative humidities are usually lower. Wind movements are also modified in cities because buildings increase the friction on air flowing around them. This friction tends to slow the speed of winds, making them far less efficient at dispersing pollutants. On the other hand, air turbulence increases because of the effect of skyscrapers on airflow. Rainfall is also increased in cities. The cause appears to be in part greater turbulence in the urban atmosphere as hot air rises from the built-up surface.
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Seventeenth - Century Dutch AgricultureAgriculture and fishing formed the primary sector of the economy in the Netherlands in the seventeenth century. Dutch agriculture was modernized and commercialized new crops and agricultural techniques raised levels of production so that they were in line with market demands, and cheap grain was imported annually from the Baltic region in large quantities. According to estimates, about 120,000 tons of imported grain fed about 600,000 people: that is about a third of the Dutch population. Importing the grain, which would have been expensive and time consuming for the Dutch to have produced themselves, kept the price of grain low and thus stimulated individual demand for other foodstuffs and consumer goods.
Apart from this, being able to give up labor-intensive grain production freed both the land and the workforce for more productive agricultural divisions. The peasants specialized in livestock husbandry and dairy farming as well as in cultivating industrial crops and fodder crops: flax, madder, and rape were grown, as were tobacco, hops, and turnips. These products were bought mostly by urban businesses. There was also a demand among urban consumers for dairy products such as butter and cheese, which, in the sixteenth century, had become more expensive than grain. The high prices encouraged the peasants to improve their animal husbandry techniques; for example, they began feeding their animals indoors in order to raise the milk yield of their cows.
In addition to dairy farming and cultivating industrial crops, a third sector of the Dutch economy reflected the way in which agriculture was being modernized-horticulture. In the sixteenth century, fruit and vegetables were to be found only in gardens belonging to wealthy people. This changed in the early part of the seventeenth century when horticulture became accepted as an agricultural sector. Whole villages began to cultivate fruit and vegetables. The produce was then transported by water to markets in the cities, where the consumption of fruit and vegetables was no longer restricted to the wealthy.
As the demand for agricultural produce from both consumers and industry increased, agricultural land became more valuable and people tried to work the available land more intensively and to reclaim more land from wetlands and lakes. In order to increase production on existing land, the peasants made more use of crop rotation and, in particular, began to apply animal waste to the soil regularly, rather than leaving the fertilization process up to the grazing livestock. For the first time industrial waste, such as ash from the soap-boilers, was collected in the cities and sold in the country as artificial fertilizer. The increased yield and price of land justified reclaiming and draining even more land.
The Dutch battle against the sea is legendary. Noorderkwartier in Holland, with its numerous lakes and stretches of water, was particularly suitable for land reclamation and one of the biggest projects undertaken there was the draining of the Beemster lake which began in 1608. The richest merchants in Amsterdam contributed money to reclaim a good 7,100 hectares of land. Forty-three windmills powered the drainage pumps so that they were able to lease the reclamation to farmers as early as 1612, with the investors receiving annual leasing payments at an interest rate of 17 percent. Land reclamation continued, and between 1590 and 1665, almost 100,000 hectares were reclaimed from the wetland areas of Holland, Zeeland, and Friesland. However, land reclamation decreased significantly after the middle of the seventeenth century because the price of agricultural products began to fall, making land reclamation far less profitable in the second part of the century.
Dutch agriculture was finally affected by the general agricultural crisis in Europe during the last two decades of the seventeenth century. However, what is astonishing about this is not that Dutch agriculture was affected by critical phenomena such as a decrease in sales and production, but the fact that the crisis appeared only relatively late in Dutch agriculture. In Europe as a whole, the exceptional reduction in the population and the related fall in demand for grain since the beginning of the seventeenth century had caused the price of agricultural products to fall. Dutch peasants were able to remain unaffected by this crisis for a long time because they had specialized in dairy farming industrial crops, and horticulture. However, toward the end of the seventeenth century, they too were overtaken by the general agricultural crisis.
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Rock Art of the Australia AboriginesEver since European first explored Australia, people have been trying to understand the ancient rock drawings and cavings created by the Aborigines, the original inhabitants of the continent. Early in the nineteenth century, encounters with Aboriginal rock art tended to be infrequent and open to speculative interpretation, but since the late nineteenth century, awareness of the extent and variety of Australian rock art has been growing. In the latter decades of the twentieth century there were intensified efforts to understand and record the abundance of Australian rock art.
The systematic study of this art is a relatively new discipline in Australia. Over the past four decades new discoveries have steadily added to the body of knowledge. The most significant data have come from a concentration on three major questions. First, what is the age of Australian rock art? Second, what is its stylistic organization and is it possible to discern a sequence or a pattern of development between styles? Third, is it possible to interpret accurately the subject matter of ancient rock art, bring to bear all available archaeological techniques and the knowledge of present-day Aboriginal informants?
The age of Australia’s rock art is constantly being revised, and earlier datings have been proposed as the result of new discoveries. Currently, reliable scientific evidence dates the earliest creation of art on rock surfaces in Australia to somewhere between 30,000 and 50,000 years ago. This in itself is an almost incomprehensible span of generations, and one that makes Australia’s rock art the oldest continuous art tradition in the world.
Although the remarkable antiquity of Australia’s rock art is now established, the sequences and meanings of its images have been widely debated. Since the mid-1970s, a reasonably stable picture has formed of the organization of Australian rock art. In order to create a sense of structure to this picture, researchers have relied on a distinction that still underlies the forms of much indigenous visual culture—a distinction between geometric and figurative elements. Simple geometric repeated patterns—circles, concentric circles, and lines—constitute the iconography (characteristic images) of the earliest rock-art sites found across Australia. The frequency with which certain simple motifs appear in these oldest sites has led rock-art researchers to adopt a descriptive term—the Panaramitee style—a label which takes its name from the extensive rock pavements at Panaramitee North in desert South Australia, which are covered with motifs pecked into the surface. Certain features of these engravings lead to the conclusion that they are of great age—geological changes had clearly happened after the designs had been made and local Aboriginal informants, when first questioned about them, seemed to know nothing of their origins. Furthermore, the designs were covered with “desert varnish,” a glaze that develops on rock surfaces over thousands of years of exposure to the elements. The simple motifs found at Panaramitee are common to many rock-art sites across Australia. Indeed, sites with engravings of geometric shapes are also to be found on the island of Tasmania, which was separated from the mainland of the continent some 10,000 years ago.
In the 1970s when the study of Australian archaeology was in an exciting phase of development, with the great antiquity of rock art becoming clear. Lesley Maynard, the archaeologist who coined the phrase “Panaramitee style,” suggested that a sequence could be determined for Australian rock art, in which a geometric style gave way to a simple figurative style (outlines of figures and animals), followed by a range of complex figurative styles that, unlike the pan-Australian geometric tradition, tended to much greater regional diversity. While accepting that this sequence fits the archaeological profile of those sites, which were occupied continuously over many thousands of years a number of writers have warned that the underlying assumption of such a sequence—a development from the simple and the geometric to the complex and naturalistic—obscures the cultural continuities in Aboriginal Australia, in which geometric symbolism remains fundamentally important. In this context the simplicity of a geometric motif may be more apparent than real. Motifs of seeming simplicity can encode complex meanings in Aboriginal Australia. And has not twentieth-century art shown that naturalism does not necessarily follow abstraction in some kind of predetermine sequence?
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Lake WaterWhere does the water in a lake come from, and how does water leave it? Water enters a lake from inflowing rivers, from underwater seeps and springs, from overland flow off the surrounding land, and from rain falling directly on the lake surface. Water leaves a lake via outflowing rivers, by soaking into the bed of the lake, and by evaporation. So much is obvious.
The questions become more complicated when actual volumes of water are considered: how much water enters and leaves by each route? Discovering the inputs and outputs of rivers is a matter of measuring the discharges of every inflowing and outflowing stream and river. Then exchanges with the atmosphere are calculated by finding the difference between the gains from rain, as measured (rather roughly) by rain gauges, and the losses by evaporation, measured with models that correct for the other sources of water loss. For the majority of lakes, certainly those surrounded by forests, input from overland flow is too small to have a noticeable effect. Changes in lake level not explained by river flows plus exchanges with the atmosphere must be due to the net difference between what seeps into the lake from the groundwater and what leaks into the groundwater. Note the word "net": measuring the actual amounts of groundwater seepage into the lake and out of the lake is a much more complicated matter than merely inferring their difference.
Once all this information has been gathered, it becomes possible to judge whether a lake’s flow is mainly due to its surface inputs and outputs or to its underground inputs and outputs. If the former are greater, the lake is a surface-water-dominated lake; if the latter, it is a seepage-dominated lake. Occasionally, common sense tells you which of these two possibilities applies. For example, a pond in hilly country that maintains a steady water level all through a dry summer in spite of having no streams flowing into it must obviously be seepage dominated. Conversely, a pond with a stream flowing in one end and out the other, which dries up when the stream dries up, is clearly surface water dominated.
By whatever means, a lake is constantly gaining water and losing water: its water does not just sit there, or, anyway, not for long. This raises the matter of a lake’s residence time. The residence time is the average length of time that any particular molecule of water remains in the lake, and it is calculated by dividing the volume of water in the lake by the rate at which water leaves the lake. The residence time is an average; the time spent in the lake by a given molecule (if we could follow its fate) would depend on the route it took: it might flow through as part of the fastest, most direct current, or it might circle in a backwater for an indefinitely long time.
Residence times vary enormously. They range from a few days for small lakes up to several hundred years for large ones; Lake Tahoe, in California, has a residence time of 700 years. The residence times for the Great Lakes of North America, namely, Lakes Superior, Michigan, Huron, Erie, and Ontario, are, respectively, 190,100,22,2.5, and 6 years. Lake Erie’s is the lowest: although its area is larger than Lake Ontario’ s, its volume is less than one-third as great because it is so shallow-less than 20 meters on average.
A given lake’s residence time is by no means a fixed quantity. It depends on the rate at which water enters the lake, and that depends on the rainfall and the evaporation rate. Climatic change (the result of global warming?) is dramatically affecting the residence times of some lakes in northwestern Ontario, Canada. In the period 1970 to 1986, rainfall in the area decreased from 1,000 millimeters to 650 millimeters per annum, while above-average temperatures speeded up the evapotranspiration rate (the rate at which water is lost to the atmosphere through evaporation and the processes of plant life).
The result has been that the residence time of one of the lakes increased from 5 to 18 years during the study period. The slowing down of water renewal leads to a chain of further consequences; it causes dissolved chemicals to become increasingly concentrated, and this, in turn, has a marked effect on all living things in the lake.
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Breathing During SleepOf all the physiological differences in human sleep compared with wakefulness that have been discovered in the last decade, changes in respiratory control are most dramatic. Not only are there differences in the level of the functioning of respiratory systems, there are even changes in how they function. Movements of the rib cage for breathing are reduced during sleep, making the contractions of the diaphragm more important. Yet because of the physics of lying down, the stomach applies weight against the diaphragm and makes it more difficult for the diaphragm to do its job. However, there are many other changes that affect respiration when asleep.
During wakefulness, breathing is controlled by two interacting systems. The first is an automatic, metabolic system whose control is centered in the brain stem. It subconsciously adjusts breathing rate and depth in order to regulate the levels of carbon dioxide (CO2) and oxygen (O2), and the acid-base ratio in the blood. The second system is the voluntary, behavioral system. Its control center is based in the forebrain, and it regulates breathing for use in speech, singing, sighing, and so on. It is capable of ignoring or overriding the automatic, metabolic system and produces an irregular pattern of breathing.
During NREM (the phase of sleep in which there is no rapid eye movement) breathing becomes deeper and more regular, but there is also a decrease in the breathing rate, resulting in less air being exchanged overall. This occurs because during NREM sleep the automatic, metabolic system has exclusive control over breathing and the body uses less oxygen and produces less carbon dioxide. Also, during sleep the automatic metabolic system is less responsive to carbon dioxide levels and oxygen levels in the blood. Two things result from these changes in breathing control that occur during sleep. First, there may be a brief cessation or reduction of breathing when falling asleep as the sleeper waxes and wanes between sleep and wakefulness and their differing control mechanisms. Second, once sleep is fully obtained, there is an increase of carbon dioxide and a decrease of oxygen in the blood that persists during NREM.
But that is not all that changes. During all phases of sleep, several changes in the air passages have been observed. It takes twice as much effort to breathe during sleep because of greater resistance to airflow in the airways and changes in the efficiency of the muscles used for breathing. Some of the muscles that help keep the upper airway open when breathing tend to become more relaxed during sleep, especially during REM (the phase of sleep in which there is rapid eye movement). Without this muscular action, inhaling is like sucking air out of a balloon—the narrow passages tend to collapse. Also there is a regular cycle of change in resistance between the two sides of the nose. If something blocks the "good" side, such as congestion from allergies or a cold, then resistance increases dramatically. Coupled with these factors is the loss of the complex interactions among the muscles that can change the route of airflow from nose to mouth.
Other respiratory regulating mechanisms apparently cease functioning during sleep. For example, during wakefulness there is an immediate, automatic, adaptive increase in breathing effort when inhaling is made more difficult (such as breathing through a restrictive face mask). This reflexive adjustment is totally absent during NREM sleep. Only after several inadequate breaths under such conditions, resulting in the considerable elevation of carbon dioxide and reduction of oxygen in the blood, is breathing effort adjusted. Finally, the coughing reflex in reaction to irritants in the airway produces not a cough during sleep but a cessation of breathing. If the irritation is severe enough, a sleeping person will arouse, clear the airway, then resume breathing and likely return to sleep.
Additional breathing changes occur during REM sleep that are even more dramatic than the changes that occur during NREM. The amount of air exchanged is even lower in REM than NREM because, although breathing is more rapid in REM,it is also more irregular, with brief episodes of shallow breathing or absence of breathing. In addition, breathing during REM depends much more on the action of the diaphragm and much less on rib cage action.
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Moving into PueblosIn the Mesa Verde area of the ancient North American Southwest, living patterns changed in the thirteenth century, with large numbers of people moving into large communal dwellings called pueblos, often constructed at the edges of canyons, especially on the sides of cliffs. Abandoning small extended-family households to move into these large pueblos with dozens if not hundreds of other people was probably traumatic. Few of the cultural traditions and rules that today allow us to deal with dense populations existed for these people accustomed to household autonomy and the ability to move around the landscape almost at will. And besides the awkwardness of having to share walls with neighbors, living in aggregated pueblos introduced other problems. For people in cliff dwellings, hauling water, wood, and food to their homes was a major chore. The stress on local resources, especially in the firewood needed for daily cooking and warmth, was particularly intense, and conditions in aggregated pueblos were not very hygienic.
Given all the disadvantages of living in aggregated towns, why did people in the thirteenth century move into these closely packed quarters? For transitions of such suddenness, archaeologists consider either pull factors (benefits that drew families together) or push factors (some external threat or crisis that forced people to aggregate). In this case, push explanations dominate.
Population growth is considered a particularly influential push. After several generations of population growth, people packed the landscape in densities so high that communal pueblos may have been a necessary outcome. Around Sand Canyon, for example, populations grew from 5 -12 people per square kilometer in the tenth century to as many as 30 - 50 by the 1200s. As densities increased, domestic architecture became larger, culminating in crowded pueblos. Some scholars expand on this idea by emphasizing a corresponding need for arable land to feed growing numbers of people: construction of small dams, reservoirs, terraces, and field houses indicates that farmers were intensifying their efforts during the 1200s. Competition for good farmland may also have prompted people to bond together to assert rights over the best fields.
Another important push was the onset of the Little Ice Age, a climatic phenomenon that led to cooler temperatures in the Northern Hemisphere. Although the height of the Little Ice Age was still around the corner, some evidence suggests that temperatures were falling during the thirteenth century. The environmental changes associated with this transition are not fully understood, but people living closest to the San Juan Mountains, to the northeast of Mesa Verde, were affected first. Growing food at these elevations is always difficult because of the short growing season. As the Little Ice Age progressed, farmers probably moved their fields to lower elevations, infringing on the lands of other farmers and pushing people together, thus contributing to the aggregations. Archaeologists identify a corresponding shift in populations toward the south and west toward Mesa Verde and away from higher elevations.
In the face of all these pushes, people in the Mesa Verde area had yet another reason to move into communal villages: the need for greater cooperation. Sharing and cooperation were almost certainly part of early Puebloan life, even for people living in largely independent single-household residences scattered across the landscape. Archaeologists find that even the most isolated residences during the eleventh and twelfth centuries obtained some pottery, and probably food, from some distance away, while major ceremonial events were opportunities for sharing food and crafts. Scholars believe that this cooperation allowed people to contend with a patchy environment in which precipitation and other resources varied across the landscape: if you produce a lot of food one year, you might trade it for pottery made by a distant ally who is having difficulty with crops—and the next year, the flow of goods might go in the opposite direction. But all of this appears to have changed thirteenth century. Although the climate remained as unpredictable as ever between one year and the next, it became much less locally diverse. In a bad year for farming, everyone was equally affected. No longer was it helpful to share widely. Instead, the most sensible thing would be for neighbors to combine efforts to produce as much food as possible, and thus aggregated towns were a sensible arrangement.
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The surface of MarsThe surface of Mars shows a wide range of geologic features, including huge volcanoes-the largest known in the solar system-and extensive impact cratering. Three very large volcanoes are found on the Tharsis bulge, an enormous geologic area near Mars’s equator. Northwest of Tharsis is the largest volcano of all: Olympus Mons, with a height of 25 kilometers and measuring some 700 kilometers in diameter at its base. The three large volcanoes on the Tharsis bulge are a little smaller-a “mere” 18 kilometers high.
None of these volcanoes was formed as a result of collisions between plates of the Martian crust-there is no plate motion on Mars. Instead, they are shield volcanoes — volcanoes with broad, sloping slides formed by molten rock. All four show distinctive lava channels and other flow features similar to those found on shield volcanoes on Earth. Images of the Martian surface reveal many hundreds of volcanoes. Most of the largest volcanoes are associated with the Tharsis bulge, but many smaller ones are found in the northern plains.
The great height of Martian volcanoes is a direct consequence of the planet’s low surface gravity. As lava flows and spreads to form a shield volcano, the volcano’s eventual height depends on the new mountain’s ability to support its own weight. The lower the gravity, the lesser the weight and the greater the height of the mountain. It is no accident that Maxwell Mons on Venus and the Hawaiian shield volcanoes on Earth rise to about the same height (about 10 kilometers) above their respective bases-Earth and Venus have similar surface gravity. Mars’s surface gravity is only 40 percent that of Earth, so volcanoes rise roughly 2.5 times as high. Are the Martian shield volcanoes still active? Scientists have no direct evidence for recent or ongoing eruptions, but if these volcanoes were active as recently as 100 million years ago (an estimate of the time of last eruption based on the extent of impact cratering on their slopes), some of them may still be at least intermittently active. Millions of years, though, may pass between eruptions.
Another prominent feature of Mars’s surface is cratering. The Mariner spacecraft found that the surface of Mars, as well as that of its two moons, is pitted with impact craters formed by meteoroids falling in from space. As on our Moon, the smaller craters are often filled with surface matter-mostly dust-confirming that Mars is a dry desert world. However, Martian craters get filled in considerably faster than their lunar counterparts. On the Moon, ancient craters less than 100 meters across (corresponding to depths of about 20 meters) have been obliterated, primarily by meteoritic erosion. On Mars, there are relatively few craters less than 5 kilometers in diameter. The Martian atmosphere is an efficient erosive agent, with Martian winds transporting dust from place to place and erasing surface features much faster than meteoritic impacts alone can obliterate them.
As on the Moon, the extent of large impact cratering (i.e. craters too big to have been filled in by erosion since they were formed) serves as an age indicator for the Martian surface. Age estimates ranging from four billion years for Mars’s southern highlands to a few hundred million years in the youngest volcanic areas were obtained in this way.
The detailed appearance of Martian impact craters provides an important piece of information about conditions just below the planet’s surface. Martian craters are surrounded by ejecta (debris formed as a result of an impact) that looks quite different from its lunar counterparts. A comparison of the Copernicus crater on the Moon with the (fairly typical) crater Yuty on Mars demonstrates the differences. The ejecta surrounding the lunar crater is just what one would expect from an explosion ejecting a large volume of dust, soil, and boulders. However, the ejecta on Mars gives the distinct impression of a liquid that has splashed or flowed out of crater. Geologists think that this fluidized ejecta crater indicates that a layer of permafrost, or water ice, lies just a few meters under the surface. Explosive impacts heated and liquefied the ice, resulting in the fluid appearance of the ejecta.
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The Decline of Venetian ShippingIn the late thirteenth century, northern Italian cities such as Genoa, Florence, and Venice began an economic resurgence that made them into the most important economic centers of Europe. By the seventeenth century, however, other European powers had taken over, as the Italian cities lost much of their economic might.
This decline can be seen clearly in the changes that affected Venetian shipping and trade. First, Venice’s intermediary functions in the Adriatic Sea, where it had dominated the business of shipping for other parties, were lost to direct trading. In the fifteenth century there was little problem recruiting sailors to row the galleys (large ships propelled by oars): guilds (business associations) were required to provide rowers, and through a draft system free citizens served compulsorily when called for. In the early sixteenth century the shortage of rowers was not serious because the demand for galleys was limited by a move to round ships (round-hulled ships with more cargo space), with required fewer rowers. But the shortage of crews proved to be a greater and greater problem, despite continuous appeal to Venic’s tradition of maritime greatness. Even though sailors’ wages doubled among the northern Italian cities from 1550 to 1590, this did not elicit an increased supply.
The problem in shipping extended to the Arsenale, Venice’s huge and powerful shipyard. Timber ran short, and it was necessary to procure it from farther and farther away. In ancient Roman times, the Italian peninsula had great forest of fir preferred for warships, but scarcity was apparent as early as the early fourteenth century. Arsenale officers first brought timber from the foothills of the Alps, then from north toward Trieste, and finally from across the Adriatic. Private shipbuilders were required to buy their oak abroad. As the costs of shipbuilding rose, Venice clung to its outdated standard while the Dutch were innovation in the lighter and more easily handled ships.
The step from buying foreign timber to buying foreign ships was regarded as a short one, especially when complaints were heard in the latter sixteenth century that the standards and traditions of the Arsenale were running down. Work was stretched out and done poorly. Older workers had been allowed to stop work a half hour before the regular time, and in 1601 younger works left with them. Merchants complained that the privileges reserved for Venetian-built and owned ships were first extended to those Venetians who bought ships from abroad and then to foreign-built and owned vessels. Historian Frederic Lane observes that after the loss of ships in battle in the late sixteenth century, the shipbuilding industry no longer had the capacity to recover that it had displayed at the start of the century.
The conventional explanation for the loss of Venetian dominance in trade is establishment of the Portuguese direct sea route to the East, replacing the overland Silk Road from the Black sea and the highly profitable Indian Ocean-caravan-eastern Mediterranean route to Venice. The Portuguese Vasco da Gama’s Voyage around southern Africa to India took place at the end of the fifteenth century, and by 1502 the trans- Abrabian caravan route had been cut off by political unrest.
The Venetian Council finally allowed round ships to enter the trade that was previously reserved for merchant galleys, thus reducing transport cost by one third. Prices of spices delivered by ship from the eastern Mediterranean came to equal those of spices transported by Paortuguese vessels, but the increase in quantity with both routes in operation drove the price far down. Gradually, Venice’s role as a storage and distribution center for spices and silk, dyes cotton, and gold decayed, and by the early seventeenth century Venice had lost its monopoly in markets such as France and southern Germany.
Venetian shipping had started to decline from about 1530-before the entry into the Mediterranean of large volumes of Dutch and British shipping-and was clearly outclassed by the end of the century. A contemporary of Shakespeare (1564-1616) observed that the productivity of Italian shipping had declined, compared with that of the British, because of conservatism and loss of expertise. Moreover, Italian sailors were deserting and emigrating, and captains, no longer recruited from the ranks of nobles, were weak on navigations.
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The Evolutionary Origin of PlantsThe evolutionary history of plants has been marked by a series of adaptations. The ancestors of plants were photosynthetic single-celled organisms that gave rise to plants presumably lacked true roots, stems, leaves, and complex reproductive structures such as flowers. All of these features appeared later in the evolutionary history of plants. Of today’s different groups of algae, green algae are probably the most similar to ancestral plants. This supposition stems from the close phylogenetic (natural evolutionary) relationship between the two groups. DNA comparisons have shown that green algae are plants’ closest living relatives. In addition, other lines of evidence support the hypothesis that land plants evolved from ancestral green algae used the same type of chlorophyll and accessory pigments in photosynthesis as do land plants. This would not be true of red and brown algae. Green algae store food as starch, as do land plants and have cell walls made of cellulose, similar in composition to those of land plants. Again, the good storage and cell wall molecules of red and brown algae are different.
Today green algae live mainly in freshwater, suggesting that their early evolutionary history may have occurred in freshwater habitats. If so, the green algae would have been subjected to environmental pressures that resulted in adaptations that enhanced their potential to give rise to land-dwelling or organisms.
The environmental conditions of freshwater habitats, unlike those of ocean habitats, are highly variable. Water temperature can fluctuate seasonally or even daily and changing level of rainfall can lead to fluctuations in the concentration of chemical in the water or even to period in which the aquatic habitat dries up. Ancient fresh water green algae must have evolved features that enable them to withstand extremes of temperature and periods of dryness. These adaptations served their descendant well asthey invaded land.
The terrestrial world is green now, but it did not start out that way. When plants first made the transition ashore more than 400 million years ago, the land was barren and desolate, inhospitable to life. From a plant’s evolutionary view point, however, it was also a land of opportunity, free of competitors and predators and full of carbon dioxide and sunlight (the raw materials for photosynthesis, which are present in far higher concentrations in air than in water).So once natural selection had shaped the adaptations that helped plants overcome the obstacles to terrestrial living, plants prospered and diversified.
When plants pioneered the land, they faced a range of challenges posed by terrestrial environments. On land, the supportive buoyancy of water is missing, the plant is no longer bathed in a nutrient solution, and air tends to dry things out. These conditions favored the evolution of the structures that support the body, vessels that transport water and nutrients to all parts of plant, and structures that conserve water. The resulting adaptations to dry land include some structural features that arose early in plant evolution; now these features are common to virtually all land plant. They include roots or root like structures, a waxy cuticle that covers the surfaces of leaves and stems and limits the evaporation of water, and pores called stomata in leaves and stems that allow gas exchange but close when water is scarce, thus reducing water loss. Other adaptations occurred later in the transition to terrestrial life and now wide spread but not universal among plants. These include conducting vessels that transport water and minerals upward from the roots and that move the photosynthetic products from the leavesto the rest of the plant body and the stiffening substance lignin, which support the plant body, helping it expose maximum surface area to sunlight.
These adaptations allowed an increasing diversity of plant forms to exploit dry land. Life on land, however, also required new methods of transporting sperm to eggs. Unlike aquatic and marine forms, land plants cannot always rely on water currents to carry their sex cells and disperse their fertilized eggs. So the most successful groups of land plants are those that evolved methods of fertilized sex cell dispersal that are independent of water and structures that protest developing embryos from drying out. Protected embryos and waterless dispersal of sex cells were achieved with the origin of seed plants and the key evolutionary innovations that they introduced: pollen, seeds, and later, flowers and fruits.
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Energy and the Industrial RevolutionFor years historians have sought to identify crucial elements in the eighteenth-century rise in industry, technology, and economic power known as the Industrial Revolution, and many give prominence to the problem of energy. Until the eighteenth century, people relied on energy derived from plants as well as animal and human muscle to provide power. Increased efficiency in the use of water and wind helped with such tasks as pumping, milling, or sailing. However, by the eighteenth century, Great Britain in particular was experiencing an energy shortage. Wood, the primary source of heat for homes and industries and also used in the iron industry as processed charcoal, was diminishing in supply. Great Britain had large amounts of coal; however, there were not yet efficient means by which to produce mechanical energy or to power machinery. This was to occur with progress in the development of the steam engine.
In the late 1700s James Watt designed an efficient and commercially viable steam engine that was soon applied to a variety of industrial uses as it became cheaper to use. The engine helped solve the problem of draining coal mines of groundwater and increased the production of coal needed to power steam engines elsewhere. A rotary engine attached to the steam engine enabled shafts to be turned and machines to be driven, resulting in mills using steam power to spin and weave cotton. Since the steam engine was fired by coal, the large mills did not need to be located by rivers, as had mills that used water- driven machines. The shift to increased mechanization in cotton production is apparent in the import of raw cotton and the sale of cotton goods. Between 1760 and 1850, the amount of raw cotton imported increased 230 times. Production of British cotton goods increased sixtyfold, and cotton cloth became Great Britain’s most important product, accounting for one-half of all exports. The success of the steam engine resulted in increased demands for coal, and the consequent increase in coal production was made possible as the steam-powered pumps drained water from the ever-deeper coal seams found below the water table.
The availability of steam power and the demands for new machines facilitated the transformation of the iron industry. Charcoal, made from wood and thus in limited supply, was replaced with coal-derived coke (substance left after coal is heated) as steam-driven bellows came into use for producing of raw iron. Impurities were burnt away with the use of coke, producing a high-quality refined iron. Reduced cost was also instrumental in developing steam-powered rolling mills capable of producing finished iron of various shapes and sizes. The resulting boom in the iron industry expanded the annual iron output by more than 170 times between 1740 and 1840, and by the 1850s Great Britain was producing more tons of iron than the rest of the world combined. The developments in the iron industry were in part a response to the demand for more machines and the ever-widening use of higher-quality iron in other industries.
Steam power and iron combined to revolutionize transport, which in turn had further implications. Improvements in road construction and sailing had occurred, but shipping heavy freight over land remained expensive, even with the use of rivers and canals wherever possible. Parallel rails had long been used in mining operations to move bigger loads, but horses were still the primary source of power. However, the arrival of the steam engine initiated a complete transformation in rail transportation, entrenching and expanding the Industrial Revolution. As transportation improved, distant and larger markets within the nation could be reached, thereby encouraging the development of larger factories to keep pace with increasing sales. Greater productivity and rising demands provided entrepreneurs with profits that could be reinvested to take advantage of new technologies to further expand capacity, or to seek alternative investment opportunities. Also, the availability of jobs in railway construction attracted many rural laborers accustomed to seasonal and temporary employment. When the work was completed, many moved to other construction jobs or to factory work in cities and towns, where they became part of an expanding working class.
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Survival of Plants and Animals in Desert ConditionsThe harsh conditions in deserts are intolerable for most plants and animals. Despite these conditions, however, many varieties of plants and animals have adapted to deserts in a number of ways. Most plant tissues die if their water content falls too low: the nutrients that feed plants are transmitted by water; water is a raw material in the vital process of photosynthesis; and water regulates the temperature of a plant by its ability to absorb heat and because water vapor lost to the atmosphere through the leaves helps to lower plant temperatures. Water controls the volume of plant matter produced. The distribution of plants within different areas of desert is also controlled by water. Some areas, because of their soil texture, topographical position, or distance from rivers or groundwater, have virtually no water available to plants, whereas others do.
The nature of plant life in deserts is also highly dependent on the fact that they have to adapt to the prevailing aridity. There are two general classes of vegetation: long-lived perennials, which may be succulent (water-storing) and are often dwarfed and woody, and annuals or ephemerals, which have a short life cycle and may form a fairly dense stand immediately after rain.
The ephemeral plants evade drought. Given a year of favorable precipitation, such plants will develop vigorously and produce large numbers of flowers and fruit. This replenishes the seed content of the desert soil. The seeds then lie dormant until the next wet year, when the desert blooms again.
The perennial vegetation adjusts to the aridity by means of various avoidance mechanisms. Most desert plants are probably best classified as xerophytes. They possess drought-resisting adaptations: loss of water through the leaves is reduced by means of dense hairs covering waxy leaf surfaces, by the closure of pores during the hottest times to reduce water loss, and by the rolling up or shedding of leaves at the beginning of the dry season. Some xerophytes, the succulents (including cacti), store water in their structures. Another way of countering drought is to have a limited amount of mass above ground and to have extensive root networks below ground. It is not unusual for the roots of some desert perennials to extend downward more than ten meters. Some plants are woody in type —an adaptation designed to prevent collapse of the plant tissue when water stress produces wilting. Another class of desert plant is the phreatophyte. These have adapted to the environment by the development of long taproots that penetrate downward until they approach the assured water supply provided by groundwater. Among these plants are the date palm, tamarisk, and mesquite. They commonly grow near stream channels, springs, or on the margins of lakes.
Animals also have to adapt to desert conditions, and they may do it through two forms of behavioral adaptation: they either escape or retreat. Escape involves such actions as aestivation, a condition of prolonged dormancy, or torpor, during which animals reduce their metabolic rate and body temperature during the hot season or during very dry spells.
Seasonal migration is another form of escape, especially for large mammals or birds. The term retreat is applied to the short-term escape behavior of desert animals, and it usually assumes the pattern of a daily rhythm. Birds shelter in nests, rock overhangs, trees, and dense shrubs to avoid the hottest hours of the day, while mammals like the kangaroo rat burrow underground.
Some animals have behavioral, physiological, and morphological (structural) adaptations that enable them to withstand extreme conditions. For example, the ostrich has plumage that is so constructed that the feathers are long but not too dense. When conditions are hot, the ostrich erects them on its back, thus increasing the thickness of the barrier between solar radiation and the skin. The sparse distribution of the feathers, however, also allows considerable lateral air movement over the skin surface, thereby permitting further heat loss by convection. Furthermore, the birds orient themselves carefully with regard to the Sun and gently flap their wings to increase convection cooling.
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Sumer and the First Cities of the Ancient Near EastThe earliest of the city states of the ancient Near East appeared at the southern end of the Mesopotamian plain, the area between the Tigris and Euphrates rivers in what is now Iraq. It was here that the civilization known as Sumer emerged in its earliest form in the fifth millennium. At first sight, the plain did not appear to be a likely home for a civilization. There were few natural resources, no timber, stone, or metals. Rainfall was limited, and what water there was rushed across the plain in the annual flood of melted snow. As the plain fell only 20 meters in 500 kilometers, the beds of the rivers shifted constantly. It was this that made the organization of irrigation, particularly the building of canals to channel and preserve the water, essential. Once this was done and the silt carried down by the rivers was planted, the rewards were rich: four to five times what rain-fed earth would produce. It was these conditions that allowed an elite to emerge, probably as an organizing class, and to sustain itself through the control of surplus crops.
It is difficult to isolate the factors that led to the next development—the emergence of urban settlements. The earliest, that of Eridu, about 4500 B.C.E., and Uruk, a thousand years later, center on impressive temple complexes built of mud brick. In some way, the elite had associated themselves with the power of the gods. Uruk, for instance, had two patron gods—Anu, the god of the sky and sovereign of all other gods, and Inanna, a goddess of love and war—and there were others, patrons of different cities. Human beings were at their mercy. The biblical story of the Flood may originate in Sumer. In the earliest version, the gods destroy the human race because its clamor had been so disturbing to them.
It used to be believed that before 3000 B.C.E. the political and economic life of the cities was centered on their temples, but it now seems probable that the cities had secular rulers from earliest times. Within the city lived administrators, craftspeople, and merchants. (Trading was important, as so many raw materials, the semiprecious stones for the decoration of the temples, timbers for roofs, and all metals, had to be imported.) An increasingly sophisticated system of administration led in about 3300 B.C.E. to the appearance of writing. The earliest script was based on logograms, with a symbol being used to express a whole word. The logograms were incised on damp clay tablets with a stylus with a wedge shape at its end. (The Romans called the shape cuneus and this gives the script its name of cuneiform.) Two thousand logograms have been recorded from these early centuries of writing. A more economical approach was to use a sign to express not a whole word but a single syllable. (To take an example: the Sumerian word for " head” was “sag.” Whenever a word including a syllable in which the sound “sag” was to be written, the sign for “sag" could be used to express that syllable with the remaining syllables of the word expressed by other signs.) By 2300 B.C.E. the number of signs required had been reduced to 600, and the range of words that could be expressed had widened. Texts dealing with economic matters predominated, as they always had done; but at this point works of theology, literature, history, and law also appeared.
Other innovations of the late fourth millennium include the wheel, probably developed first as a more efficient way of making pottery and then transferred to transport. A tablet engraved about 3000 B.C.E. provides the earliest known example from Sumer, a roofed boxlike sledge mounted on four solid wheels. A major development was the discovery, again about 3000 B.C.E., that if copper, which had been known in Mesopotamia since about 3500 B.C.E., was mixed with tin, a much harder metal, bronze, would result. Although copper and stone tools continued to be used, bronze was far more successful in creating sharp edges that could be used as anything from saws and scythes to weapons. The period from 3000 to 1000 B.C.E., when the use of bronze became widespread, is normally referred to as the Bronze Age.
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Crafts in the Ancient Near EastSome of the earliest human civilizations arose in southern Mesopotamia, in what is now southern Iraq, in the fourth millennium B.C.E. In the second half of the millennium, in the south around the city of Uruk, there was an enormous escalation in the area occupied by permanent settlements. A large part of that increase took place in Uruk itself, which became a real urban center surrounded by a set of secondary settlements. While population estimates are notoriously unreliable, scholars assume that Uruk inhabitants were able to support themselves from the agricultural production of the field surrounding the city, which could be reached with a daily commute. But Uruk’s dominant size in the entire region, far surpassing that of other settlements, indicates that it was a regional center and a true city. Indeed, it was the first city in human history.
The vast majority of its population remained active in agriculture, even those people living within the city itself. But a small segment of the urban society started to specialize in nonagricultural tasks as a result of the city’s role as a regional center. Within the productive sector, there was a growth of a variety of specialist craftspeople. Early in the Uruk period, the use of undecorated utilitarian pottery was probably the result of specialized mass production. In an early fourth-millennium level of the Eanna archaeological site at Uruk, a pottery style appears that is most characteristic of this process, the so-called beveled-rim bowl. It is a rather shallow bowl that was crudely made in a mold; hence, in only a limited number of standard sizes. For some unknown reason, many were discarded, often still intact, and thousands have been found all over the Near East. The beveled-rim bowl is one of the most telling diagnostic finds for identifying an Uruk-period site. Of importance is the fact that it was produced rapidly in large amounts, most likely by specialists in a central location.
A variety of documentation indicates that certain goods, once made by a family member as one of many duties, were later made by skilled artisans. Certain images depict groups of people, most likely women, involved in weaving textiles, an activity we know from later third-millennium texts to have been vital in the economy and to have been centrally administered. Also, a specialized metal-producing workshop may have been excavated in a small area at Uruk. It contained a number of channels lined by a sequence of holes, about 50 centimeters deep, all showing burn marks and filled with ashes. This has been interpreted as the remains of a workshop where molten metal was scooped up from the channel and poured into molds in the holes. Some type of mass production by specialists were involved here.
Objects themselves suggest that they were the work of skilled professionals. In the late Uruk period(3500-3100 B.C.E.), there first appeared a type of object that remained characteristic for Mesopotamia throughout its entire history: the cylinder seal. This was a small cylinder, usually no more than 3 centimeters high and 2 centimeters in diameter, of shell, bone, faience (a glassy type of stoneware), or various types of stones, on which a scene was carved into the surface. When rolled over a soft material----primarily the clay of bullae (round seals), tablets, or clay lumps attached to boxes, jars, or door bolts----the scene would appear in relief, easily legible. The technological knowledge needed to carved it was far superior to that for stamp seals, which had happened in the early Neolithic period (approximately 10,000-5000 B.C.E.). From the first appearance of cylinder seals, the carved scenes could be highly elaborate and refined, indicating the work of specialist stone-cutters. Similarly, the late Uruk period shows the first monumental art, relief, and statuary in the round, made with a degree of mastery that only a professional could have produced.
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The Formation of Volcanic IslandsEarth’s surface is not made up of a single sheet of rock that forms a crust but rather a number of “tectonic plates” that fit closely, like the pieces of a giant jigsaw puzzle. Some plates carry islands or continents others form the seafloor. All are slowly moving because the plates float on a denser semi-liquid mantle, the layer between the crust and Earth’s core. The plates have edges that are spreading ridges (where two plates are moving apart and new seafloor is being created), subduction zones (where two plates collide and one plunges beneath the other), or transform faults (where two plates neither converge nor diverge but merely move past one another). It is at the boundaries between plates that most of Earth’s volcanism and earthquake activity occur.
Generally speaking, the interiors of plates are geologically uneventful. However, there are exceptions. A glance at a map of the Pacific Ocean reveals that there are many islands far out at sea that are actually volcanoes----many no longer active, some overgrown with coral----that originated from activity at points in the interior of the Pacific Plate that forms the Pacific seafloor.
How can volcanic activity occur so far from a plate boundary? The Hawaiian Islands provide a very instructive answer.Like many other island groups, they form a chain. The Hawaiian Islands Chain extends northwest from the island of Hawaii. In the 1840s American geologist James Daly observed that the different Hawaii islands seem to share a similar geologic evolution but are progressively more eroded, and therefore probable older, toward the northwest. Then in 1963, in the early days of the development of the theory of plate tectonics. Canadian geophysicist Tuzo Wilson realized that this age progression could result if the islands were formed on a surface plate moving over a fixed volcanic source in the interior. Wilson suggested that the long chain of volcanoes stretching northwest from Hawaii is simply the surface expression of a long-lived volcanic source located beneath the tectonic plate in the mantle. Today’s most northwest island would have been the first to form. They as the plate moved slowly northwest, new volcanic islands would have forms as the plate moved over the volcanic source. The most recent island, Hawaii, would be at the end of the chain and is now over the volcanic source.
Although this idea was not immediately accepted, the dating of lavas in the Hawaii (and other) chains showed that their ages increase away from the presently active volcano, just as Daly had suggested. Wilson’s analysis of these data is now a central part of plate tectonics. Most volcanoes that occur in the interiors of plates are believed to be produced by mantle plumes, columns of molten rock that rise from deep within the mantle. A volcano remains an active “hot spot” as long as it is over the plume. The plumes apparently originate at great depths, perhaps as deep as the boundary between the core and the mantle, and many have been active for a very long time. The oldest volcanoes in the Hawaii hot-spot trail have ages close to 80 million years. Other islands, including Tahiti and Easter Islands in the pacific, Reunion and Mauritius in the India Ocean, and indeed most of the large islands in the world’s oceans, owe their existence to mantle plumes.
The oceanic volcanic islands and their hot-spot trails are thus especially useful for geologist because they record the past locations of the plate over a fixed source. They therefore permit the reconstruction of the process of seafloor spreading, and consequently of the geography of continents and of ocean basins in the past. For example, given the current position of the Pacific Plate, Hawaii is above the Pacific Ocean hot spot. So the position of The Pacific Plate 50 million years ago can be determined by moving it such that a 50-million-year-old volcano in the hot-spot trail sits at the location of Hawaii today. However because the ocean basins really are short-lived features on geologic times scale, reconstruction the world’s geography by backtracking along the hot-spot trail works only for the last 5 percent or so of geologic time.
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Predator Prey CyclesHow do predators affect populations of the prey animals? The answer is not as simple as might be thought. Moose reached Isle Royale in Lake Superior by crossing over winter ice and multiplied freely there in isolation without predators. When wolves later reached the island, naturalists widely assumed that the wolves would play a key role in controlling the moose population. Careful studies have demonstrated, however, that this is not the case. The wolves eat mostly old or diseased animals that would not survive long anyway. In general, the moose population is controlled by food availability, disease and other factors rather than by wolves.
When experimental populations are set up under simple laboratory conditions, the predator often exterminates its prey and then becomes extinct itself, having nothing left to eat. However, if safe areas like those prey animals have in the wild are provided, the prey population drops to low level but not extinction. Low prey population levels then provide inadequate food for the predators, causing the predator population to decrease. When this occurs, the prey population can rebound. In this situation the predator and prey population may continue in this cyclical pattern for some time.
Population cycles are characteristic of small mammals, and they sometimes appear to be brought about by predators. Ecologists studying hare populations have found that the North American snow shoe hare follows a roughly ten-year cycle. Its numbers fall tenfold to thirty in a typical cycle, and a hundredfold change can occur. Two factors appear to be generating the cycle: food plants and predators.
The preferred foods of snowshoe hares are willow and birch twigs. As hare density increases, the quantity of these twigs decreases, forcing the hares to feed on low-quality high-fiber food. Lower birth rates, low juvenile survivorship, and low growth rates follow, so there is a corresponding decline in hare abundance. Once the hare population has declined, it takes two to three year for the quantity of twigs to recover.
A key predator of the snowshoe hare is the Canada lynx. The Canada lynx shows a ten-year cycle of abundance that parallels the abundance cycle of hares. As hare numbers fall, so do lynx numbers, as their food supply depleted.
What causes the predator-prey oscillations? Do increasing number of hares lead to overharvesting of plants, which in turn results in reduced hare populations, or do increasing numbers of lynx lead to overharvesting hares? Field experiments carried out by Charles Krebs and coworkers in 1992 provide an answer. Krebs investigated experimental plots in Canada’s Yukon territory that contained hare populations. When food was added to those plots (no food effect) and predators were excluded (no predator effect) from an experimental area, hare numbers increased tenfold and stayed there—the cycle was lost. However, the cycle was retained if either of the factors was allowed to operate alone: if predators were excluded but food was not added (food effect alone), or if food was added in the presence of predators (predator effect alone). Thus both factors can affect the cycle, which, in practice, seems to be generated by conjunction of the two factors.
Predators are an essential factor in maintaining communities that are rich and diverse in species. Without predators, the species that is the best competitor for food, shelter, nesting sites, and other environmental resources tends to dominate and exclude the species with which it competes. This phenomenon is known as “competitor exclusion”. However, if the community contains a predator of the strongest competitor species, then the population of that competitor is controlled. Thus even the less competitive species are able to survive. For example, sea stars prey on a variety of bivalve mollusks and prevent these bivalves from monopolizing habitats on the sea floor. This opens up space for many other organisms. When sea stars are removed, species diversity falls sharply. Therefore, from the stand point of diversity, it is usually a mistake to eliminate a major predator from a community.
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GroundwaterMost of the world’s potable water----freshwater suitable for drinking----is accounted for by groundwater, which is stored in the pores and fractures in rocks. There is more than 50 times as much freshwater stored underground than in all the freshwater rivers and lakes at the surface. Nearly 50 percent of all groundwater is stored in the upper 1,000 meters of Earth. At greater depths within Earth, the pressure of the overlying rock causes pores and cracks to close, reducing the space that pore water can occupy, and almost complete closure occurs at a depth of about 10 kilometers. The greatest water storage, therefore, lies near the surface.
Aquifers, Porosity and Permeability
Groundwater is stored in a variety of rock types. A groundwater reservoir from which water can be extracted is called an aquifer. We can effectively think of an aquifer as a deposit of water. Extraction of water depends on two properties of the aquifer: porosity and permeability. Between sediment grains are spaces that can be filled with water. This pore space is known as porosity and is expressed as a percentage of the total rock volume. Porosity is important for water-storage capacity, but for water to flow through rocks, the pore spaces must be connected. The ability of water, or other fluids, to flow through the interconnected pore spaces in rocks is termed permeability. In the intergranular spaces of rocks, however, fluid must flow around and between grains in a tortuous path; this winding path causes a resistance to flow. The rate at which the flowing water overcomes this resistance is related to the permeability of rock.
Sediment sorting and compaction influence permeability and porosity. The more poorly sorted or the more tightly compacted a sediment is ,the lower its porosity and permeability. Sedimentary rocks----the most common rock type near the surface----are also the most common reservoirs for water because they contain the most space that can be filled with water. Sandstones generally make good aquifers, while finer-grained mudstones are typically impermeable. Impermeable rocks are referred to as aquicludes. Igneous and metamorphic rocks are more compact, commonly crystalline, and rarely contain spaces between grains. However, even igneous and metamorphic rocks may act as groundwater reservoirs if extensive fracturing occurs in such rocks and if the fracture system is interconnected.
The Water Table
The water table is the underground boundary below which all the cracks and pores are filled with water. In some cases, the water table reaches Earth’s surface, where it is expressed as rivers, lakes and marshes. Typically, though, the water table may be tens or hundreds of meters below the surface. The water table is not flat but usually follows the contours of the topography. Above the water table is the vadose zone, through which rainwater percolates. Water in the vadose zone drains down to the water table, leaving behind a thin coating of water on mineral grains. The vadose zone supplies plant roots near the surface with water.
Because the surface of the water table is not flat but instead rises and falls with topography, groundwater is affected by gravity in the same fashion as surface water. Groundwater flows downhill to topographic lows. If the water table intersect the land surface, groundwater will flow out onto the surface at springs, whether to be collected there or to subsequently flow farther along a drainage. Groundwater commonly collects in stream drainages but may remain entirely beneath the surface of dry stream-beds in arid regions. In particularly wet years, short stretches of an otherwise dry stream-bed may have flowing water because the water table rises to intersect the land surface.
Sediment: materials (such as sand or small rocks) that are deposited by water, wind, or glacial ice.
Topography: the shape of a surface such as Earth’s, including the rise and fall of such features as mountains and valleys.
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Early Saharan PastoralistsThe Sahara is a highly diverse, albeit dry, region that has undergone major climatic changes since 10,000 B.C. As recently as 6,000 B.C. the southern frontier of the desert was far to the north of where it is now, while semiarid grassland and shallow freshwater lakes covered much of what are now arid plains. This was a landscape where antelope of all kinds abounded----along with Bos primigenius, a kind of oxen that has become extinct. The areas that are now desert were, like all arid regions, very susceptible to cycles of higher and lower levels of rainfall, resulting in major, sudden changes in distributions of plants and animals. The people who hunted the sparse desert animals responded to drought by managing the wild resources they hunted and gathered, especially wild oxen, which had to have regular water supplies to survive.
Even before the drought, the Sahara was never well watered. Both humans and animals were constantly on the move, in search of food and reliable water supplies. Under these circumstances, archaeologist Andrew Smith believes, the small herds of Bos primigenius in the desert became smaller, more closely knit breeding units as the drought took hold. The beasts were more disciplined, so that it was easier for hunters to predict their habits, and capture animals at will. At the same time, both cattle and humans were more confined in their movements, staying much closer to permanent water supplies for long periods of time. As a result, cattle and humans came into close association.
Smith believes that the hunters were well aware of the more disciplined ways in which their prey behaved. Instead of following the cattle on their annual migrations, the hunters began to prevent the herd from moving from one spot to another. At first, they controlled the movement of the herd while ensuring continuance of their meat diet. But soon they also gained genetic control of the animals, which led to rapid physical changes in the herd. South African farmers who maintain herds of wild eland (large African antelopes with short, twisted horns) report that the offspring soon diminish in size, unless wild bulls are introduced constantly from outside. The same effects of inbreeding may have occurred in controlled cattle populations, with some additional, and perhaps unrecognized, advantages. The newly domesticated animals behaved better, were easier to control, and may have enjoyed a higher birth rate, which in turn yielded greater milk supplies. We know from rock paintings deep in the Sahara that the herders were soon selecting breeding animals to produce offspring with different horn shapes and hide colors.
It is still unclear whether domesticated cattle were tamed independently in northern Africa or introduced to the continent from southwest Asia. Whatever the source of the original tamed herds might have been, it seems entirely likely that much the same process of juxtaposition (living side by side) and control occurred in both southwest Asia and northern Africa, and even in Europe, among peoples who had an intimate knowledge of the behavior of wild cattle. The experiments with domestication probably occurred in many places, as people living in ever-drier environments cast around for more predictable food supplies.
The cattle herders had only a few possessions: unsophisticated pots and polished adzes. They also hunted with bow and arrow. The Saharan people left a remarkable record of their lives painted on the walls of caves deep in the desert. Their artistic endeavors have been preserved in paintings of wild animals, cattle, goats, humans, and scenes of daily life that extend back perhaps to 5,000 B.C.. The widespread distribution of pastoral sites of this period suggests that the Saharans ranged their herds over widely separated summer and winter grazing grounds.
About 3,500 B.C., climatic conditions again deteriorated. The Sahara slowly became drier and lakes vanished. On the other hand, rainfall increased in the interior of western Africa, and the northern limit of the tsetse fly, an insect fatal to cattle, moved south. So the herders shifted south, following the major river systems into savanna regions. By this time, the Saharan people were probably using domestic crops, experimenting with such summer rainfall crops as sorghum and millet as they move out of areas where they could grow wheat, barley, and other Mediterranean crops.
adzes: cutting tools with blades set at right angles to the handle.
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"Buck Rubs and Buck ScrapesA conspicuous sign indicating the presence of white-tailed deer in a woodlot is a buck rub. A male deer makes a buck rub by striping the bark (outer layer) of a small tree with its antlers. When completed, the buck rub is an obvious visual signal to us and presumable to other deer in the area. A rub is usually located at the shoulder height of a deer (one meter or less above the ground) on a smooth-barked, small-diameter (16-25 millimeters) tree. The smooth bark of small red maples makes this species ideal for buck rubs in the forests of the mid-eastern United States.
Adult male deer usually produce rubs in late summer or early autumn when the outer velvet layer is being shed from their antlers. Rubs are created about one to two months before the breeding season (the rut). Hence for a long time biologists believed that male deer used buck rubs not only to clean and polish antlers but also to provide practice for the ensuing male-to-male combat during the rut. However, biologists also noted deer sniff and lick an unfamiliar rub, which suggests that this visual mark on a small tree plays an important communication purpose in the social life of deer.
Buck rubs also have a scent produced by glands in the foreheads of deer that is transferred to the tree when the rub is made. These odors make buck rubs an important means of olfactory communication between deer. The importance of olfactory communication (using odors to communicate) in the way of life of deer was documented by a study of captive adult male deer a few decades ago, which noted that males rubbed their foreheads on branches and twigs, especially as autumn approached. A decade later another study reported that adult male white-tailed deer exhibited forehead rubbing just before and during the rut. It was found that when a white-tailed buck makes a rub, it moves both antlers and forehead glands along the small tree in a vertical direction. This forehead rubbing behavior coincides with a high level of glandular activity in the modified scent glands found on the foreheads of male deer; the glandular activity causes the forehead pelage (hairy covering) of adult males to be distinctly darker than in females or younger males.
Forehead rubbing by male deer on buck rubs presumably sends a great deal of information to other members of the same species. First, the chemicals deposited on the rub provide information on the individual identity of an animal; no two mammals produce the same scent. For instance, as we all know, dogs recognize each other via smell. Second, because only male deer rub, the buck rub and its associated chemicals indicate the sex of the deer producing the rub. Third, older, more dominant bucks produce more buck rubs and probably deposit more glandular secretions on a given rub. Thus the presence of many well-marked rubs is indicative of older, higher-status males being in the general vicinity rather than simply being a crude measure of relative deer abundance in a given area. The information conveyed by the olfactory signals on a buck rub make it the social equivalent of some auditory signals in other deer species, such as trumpeting by bull elk.
Because both sexes of white-tailed respond to buck rubs by smelling and licking them, rubs may serve a very important additional function. Fresher buck rubs (less than two days old), in particular, are visited more frequently by adult females than older rubs. In view of this behavior it has been suggested that chemicals present in fresh buck rubs may help physiologically induce and synchronize fertility in females that visit these rubs. This would be an obvious advantage to wide-ranging deer, especially to a socially dominant buck when courting several adult females during the autumn rut. Another visual signal produced by while-tailed deer is termed a buck scrape. Scrapes consist of a clearing (about 0.5 meter in diameter) and shallow depression made by pushing aside the leaves covering the ground; after making the scrape, the deer typically urinates in the depression. Thus, like a buck rub, a scrape is both a visual and an olfactory signal. Buck scrapes are generally created after leaf-fall in autumn, which is just before or during the rut. Scrapes are usually placed in open or conspicuous places, such as along a deer trail. Most are made by older males, although females and younger males (2.5 years old or less) occasionally make scrapes. "
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Characteristics of Roman PotteryThe pottery of ancient Romans is remarkable in several ways. The high quality of Roman pottery is very easy to appreciate when handling actual pieces of tableware or indeed kitchenware and amphorae (the large jars used throughout the Mediterranean for the transport and storage of liquids, such as wine and oil). However, it is impossible to do justice to Roman wares on the page, even when words can be backed up by photographs and drawing. Most Roman pottery is light and smooth to touch and very tough, although, like all pottery, it shatters if dropped on a hard surface. It is generally made with carefully selected and purified clay, worked to thin-walled and standardized shapes on a fast wheel and fired in a kiln (pottery oven) capable of ensuring a consistent finish. With handmade pottery, inevitably there are slight differences between individual vessels of the same design and occasional minor blemishes (flaws). But what strikes the eye and the touch most immediately and most powerfully with Roman pottery is its consistent high quality.
This is not just an aesthetic consideration but also a practical one. These vessels are solid (brittle, but not fragile), they are pleasant and easy to handle (being light and smooth), and, with their hard and sometimes glossy (smooth and shiny) surfaces, they hold liquids well and are easy to wash. Furthermore, their regular and standardized shapes would have made them simple to stack and store. When people today are shown a very ordinary Roman pot and, in particular, are allowed to handle it, they often comment on how modern it looks and feels, and they need to be convinced of its true age.
As impressive as the quality of Roman pottery is its sheer massive quantity. When considering quantities, we would ideally like to have some estimates for overall production from particular sites of pottery manufacture and for overall consumption at specific settlements. Unfortunately, it is in the nature of the archaeological evidence, which is almost invariable only a sample of what once existed, that such figures will always be elusive. However, no one who has ever worked in the field would question the abundance of Roman pottery, particularly in the Mediterranean region. This abundance is notable in Roman settlements (especially urban sites) where the labor that archaeologists have to put into the washing and sorting of potsherds (fragments of pottery) constitutes a high proportion of the total work during the initial phases of excavation.
Only rarely can we derive any “real” quantities from deposits of broken pots. However, there is one exceptional dump, which does represent a very large part of the site’s total history of consumption and for which an estimate of quantity has been produced. On the left bank of the Tiber River in Rome, by one of the river ports of the ancient city, is a substantial hill some 50 meters high called Monte Testaccio. It is made up entirely of broken oil amphorae, mainly of the second and third centuries A.D. It has been estimated that Monte Testaccio contains the remains of some 53 million amphorae, in which around 6,000million liters of oil were imported into the city from overseas, imports into imperial Rome were supported by the full might of the state and were therefore quite exceptional----but the size of the operations at Monte Testaccio, and the productivity and complexity that lay behind them, nonetheless cannot fail to impress. This was a society with similarities to modern one----moving goods on a gigantic scale, manufacturing high-quality containers to do so, and occasionally, as here, even discarding them on delivery.
Roman pottery was transported not only in large quantities but also over substantial distances. Many Roman pots, in particular amphorae and the fine wares designed for use at tables, could travel hundreds of miles----all over the Mediterranean and also further afield. But maps that show the various spots where Roman pottery of a particular type has been found tell only part of the story. What is more significant than any geographical spread is the access that different levels of society had to good-quality products. In all but the remotest regions of the empire, Roman pottery of a high standard is common at the sites of humble villages and isolated farmsteads.
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CompetitionWhen several individuals of the same species or of several different species depend on the same limited resource, a situation may arise that is referred to as competition. The existence of competition has been long known to naturalists; its effects were described by Darwin in considerable detail. Competition among individuals of the same species (intraspecies competition), one of the major mechanisms of natural selection, is the concern of evolutionary biology. Competition among the individuals of different species (interspecies competition) is a major concern of ecology. It is one of the factors controlling the size of competing populations, and extreme cases it may lead to the extinction of one of the competing species. This was described by Darwin for indigenous New Zealand species of animals and plants, which died out when competing species from Europe were introduced.
No serious competition exists when the major needed resource is in superabundant supply, as in most cases of the coexistence of herbivores (plant eaters). Furthermore, most species do not depend entirely on a single resource, if the major resource for a species becomes scarce, the species can usually shift to alternative resources. If more than one species is competing for a scarce resource, the competing species usually switch to different alternative resources. Competition is usually most severe among close relatives with similar demands on the environment. But it may also occur among totally unrelated forms that compete for the same resource, such as seed-eating rodents and ants. The effects of such competition are graphically demonstrated when all the animals or all the plants in an ecosystem come into competition, as happened 2 million years ago at the end of Pliocene, when North and South America became joined by the Isthmus of Panama. North and South American species migrating across the Isthmus now came into competition with each other. The result was the extermination of a large fraction of the South American mammals, which were apparently unable to withstand the competition from invading North American species----although added predation was also an important factor.
To what extent competition determines the composition of a community and the density of particular species has been the source of considerable controversy. The problem is that competition ordinarily cannot be observed directly but must be inferred from the spread or increase of one species and the concurrent reduction or disappearance of another species. The Russian biologist G. F. Gause performed numerous tow-species experiments in the laboratory, in which one of the species became extinct when only a single kind of resource was available. On the basis of these experiments and of field observations, the so-called law of competitive exclusion was formulated, according to which no two species can occupy the same niche. Numerous seeming exceptions to this law have since been found, but they can usually be explained as cases in which the two species, even though competing for a major joint resource, did not really occupy exactly the same niche.
Competition among species is of considerable evolutionary importance. The physical structure of species competing for resources in the same ecological niche tends to gradually evolve in ways that allow them to occupy different niches. Competing species also tend to change their ranges so that their territories no longer overlap. The evolutionary effect of competition on species has been referred to as “species selection”; however, this description is potentially misleading. Only the individuals of a species are subject to the pressures of natural selection. The effect on the well-being and existence of a species is just the result of the effects of selection on all the individuals of the species. Thus species selection is actually a result of individual selection.
Competition may occur for any needed resource. In the case of animals it is usually food; in the case of forest plants it may be light; in the case of substrate inhabitants it may be space, as in many shallow-water bottom-dwelling marine organisms. Indeed, it may be for any of the factors, physical as well as biotic, that are essential for organisms. Competition is usually the more severe the denser the population. Together with predation, it is the most important density-dependent factor in regulating population growth.
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The History of WaterpowerMoving water was one of the earliest energy sources to be harnessed to reduce the workload of people and animals. No one knows exactly when the waterwheel was invented, but irrigation systems existed at least 5,000 years ago, and it seems probable that the earliest waterpower device was the noria, a waterwheel that raised water for irrigation in attached jars. The device appears to have evolved no later than the fifth century B.C., perhaps independently in different regions of the Middle and Far East.
The earliest waterpower mills were probably vertical-axis mills for grinding corn, known as Norse or Greek mills, which seem to have appeared during the first or second century B.C. in the Middle East and a few centuries later in Scandinavia. In the following centuries, increasingly sophisticated waterpower mills were built throughout the Roman Empire and beyond its boundaries in the Middle East and northern Europe. In England, the Saxons are thought to have used both horizontal0 and vertical-axis wheels. The first documented English mill was in the eighth century, but three centuries later about 5,000 were recorded, suggesting that every settlement of any size had its mill.
Raising water and grinding corn were by no means the only uses of the waterpower mill, and during the following centuries, the applications of waterpower kept pace with the developing technologies of mining, iron working, paper making, and the wool and cotton industries. Water was the main source of mechanical power, and by the end of the seventeenth century, England alone is thought to have had some 20,000 working mill.
There was much debate on the relative efficiencies of different types of waterwheels. The period from about 1650 until 1800 saw some excellent scientific and technical investigations of different designs. They revealed output powers ranging from about 1 horsepower to perhaps 60 for the largest wheels and confirmed that for maximum efficiency, the water should pass across the blades as smoothly as possible and fall away with minimum speed, having given up almost all of its kinetic energy. (They also proved that, in principle, the overshot wheel, a type of wheel in which an overhead stream of water powers the wheel, should win the efficiency competition.)
But then steam power entered the scene, putting the whole future of waterpower in doubt. An energy analyst writing in the year 1800 would have painted a very pessimistic picture of the future for waterpower. The coal-fired steam engine was taking over, and the waterwheel was fast becoming obsolete. However, like many later experts, this one would have suffered from an inability to see into the future. A century later the picture was completely different: by then, the world had an electric industry, and a quarter of its generating capacity was water powered.
The growth of the electric-power industry was the result of a remarkable series of scientific discoveries and development in electrotechnology during the nineteenth century, but significant changes in what we might now call hydro (water) technology also played their part. In 1832, the year of Michael Faraday’s discovery that a changing magnetic field produces an electric field, a young French engineer patented a new and more efficient waterwheel. His name was Benoit Fourneyron, and his device was the first successful water turbine. (The word turbine comes form the Latin turbo: something that spins). The waterwheel, unaltered for nearly 2,000 years, had finally been superseded.
Half a century of development was needed before Faraday’s discoveries in electricity were translated into full-scale power stations. In 1881 the Godalming power station in Surrey, England, on the banks of the Wey River, created the world’s first public electricity supply. The power source of this most modern technology was a traditional waterwheel. Unfortunately this early plant experienced the problem common to many forms of renewable energy: the flow in the Wey River was unreliable, and the waterwheel was soon replaced by a steam engine.
From this primitive start, the electric industry grew during the final 20 years of the nineteenth century at a rate seldom if ever exceeded by any technology. The capacity of individual power stations, many of them hydro plants, rose from a few kilowatts to over a megawatt in less than a decade.
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Role of Play in DevelopmentPlay is easier to define with examples than with concepts. In any case, in animals it consists of leaping, running, climbing, throwing, wrestling, and other movements, either along, with objects, or with other animals. Depending on the species, play may be primarily for social interaction, exercise, or exploration. One of the problems in providing a clear definition of play is that it involves the same behaviors that take place in other circumstance--dominance, predation, competition, and real fighting. Thus, whether play occurs or not depends on the intention of the animals, and the intentions are not always clear from behaviors alone.
Play appears to be a developmental characteristic of animals with fairly sophisticated nervous systems, mainly birds and mammals. Play has been studied most extensively in primates and canids (dogs). Exactly why animals play is still a matter debated in the research literature, and the reasons may not be the same for every species that plays. Determining the functions of play is difficult because the functions may be long-term, with beneficial effects not showing up until the animal's adulthood.
Play is not without considerable costs to the individual animal. Play is usually very active, involving movement in space and, at times, noisemaking. Therefore, it results in the loss of fuel or energy that might better be used for growth or for building up fat stores in a young animal. Another potential cost of this activity is greater exposure to predators since play is attention-getting behavior. Great activities also increase the risk of injury in slipping or falling.
The benefits of play must outweigh costs, or play would not have evolved, according to Darwin' s theory. Some of the potential benefits relate directly to the healthy development of the brain and nervous system. In one research study, two groups of young rats were raised under different conditions. One group developed in an "enriched" environment, which allowed the rats to interact with other rats, play with toys, and receive maze training. The other group lived in an "impoverished" environment in individual cages in a dimly lit room with little stimulation. At the end of the experiments, the results showed that the actual weight of the brains of the impoverished rats was less than that of those raised in the enriched environment (though they were fed the same diets). Other studies have shown that greater stimulation not only affects the size of the brain but also increase the number of connections between the nerve cells. Thus, active play may provide necessary stimulation to the growth of synaptic connections in the brain, especially the cerebellum, which is responsible for motor functioning and movements.
Play also stimulates the development of the muscle tissues themselves and may provide the opportunities to practice those movements needed for survival. Prey species, like young deer or goats, for example, typically play by performing sudden flight movements and turns, whereas predator species, such as cats, practice stalking, pouncing, and biting.
Play allows a young animal to explore its environment and practice skill in comparative safety since the surrounding adults generally do not expect the young to deal with threats or predators. Play can also provide practice in social behaviors needed for courtship and mating. Learning appropriate social behaviors is especially important for species that live in groups, like young monkeys that needed to learn to control selfishness and aggression and to understand the give-and-take involved in social groups. They need to learn how to be dominant and submissive because each monkey might have to play either role in the future. Most of these things are learned in the long developmental periods that primates have, during which they engage in countless play experiences with their peers.
There is a danger, of course, that play may be misinterpreted or not recognized as play by others, potentially leading to aggression. This is especially true when play consists of practicing normal aggressive or predator behaviors. Thus, many species have evolved clear signals to delineate playfulness. Dogs, for example, will wag their tails, get down their front legs, and stick their behinds in the air to indicate "what follows is just for play."
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The Pace of Evolutionary ChangeA heated debate has enlivened recent studies of evolution. Darwin' s original thesis, and the viewpoint supported by evolutionary gradualists, is that species change continuously but slowly and in small increments. Such changes are all but invisible over the short time scale of modern observations, and, it is argued, they are usually obscured by innumerable gaps in the imperfect fossil record. Gradualism, with its stress on the slow pace of change, is a comforting position, repeated over and over again in generations of textbooks. By the early twentieth century, the question about the rate of evolution had been answered in favor of gradualism to most biologists' satisfaction.
Sometimes a closed question must be reopened as new evidence or new arguments based on old evidence come to light. In 1972 paleontologist Stephen Jay Gould and Niles Eldredge challenged conventional wisdom with an opposing viewpoint, the punctuated equilibrium hypothesis, which posits that species give rise to new species in relatively sudden bursts, without a lengthy transition period. These episodes of rapid evolution are separated by relatively long static spans during which a species may hardly change at all.
The punctuated equilibrium hypothesis attempts to explain a curious feature of the fossil record --- one that has been familiar to paleontologist for more than a century but has usually been ignored. Many species appear to remain unchanged in the fossil record for millions of years --- a situation that seems to be at odds with Darwin' s model of continuous change. Intermediated fossil forms, predicted by gradualism, are typically lacking. In most localities a given species of clam or coral persists essentially unchanged throughout a thick formation of rock, only to be replaced suddenly by a new and different species.
The evolution of North American horse, which was once presented as a classic textbook example of gradual evolution, is now providing equally compelling evidence for punctuated equilibrium. A convincing 50-million-year sequence of modern horse ancestors --- each slightly larger, with more complex teeth, a longer face, and a more prominent central toe ---seemed to provide strong support for Darwin' s contention that species evolve gradually. But close examination of those fossil deposits now reveals a somewhat different story. Horses evolved in discrete steps, each of which persisted almost unchanged for millions of years and was eventually replaced by a distinctive newer model. The four-toed Eohippus preceded the three-toed Miohippus, for example, but North American fossil evidence suggests a jerky, uneven transition between the two. If evolution had been a continuous, gradual process, one might expect that almost every fossil specimen would be slightly different from every year.
If it seems difficult to conceive how major changes could occur rapidly, consider this: an alteration of a single gene in files is enough to turn a normal fly with a single pair of wings into one that has two pairs of wings.
The question about the rate of evolution must now be turned around: does evolution ever proceed gradually, or does it always occur in short bursts? Detailed field studies of thick rock formations containing fossils provide the best potential tests of the competing theories.
Occasionally , a sequence of fossil-rich layers of rock permits a comprehensive look at one type of organism over a long period of time. For example, Peter Sheldon' s studies of trilobites, a now extinct marine animal with a segmented body, offer a detailed glimpse into three million years of evolution in one marine environment. In that study, each of eight different trilobite species was observed to undergo a gradual change in the number of segments --- typically an increase of one or two segments over the whole time interval. No significant discontinuous were observed, leading Sheldon to conclude that environmental conditions were quite stable during the period he examined.
Similar exhaustive studies are required for many different kinds of organisms from many different periods. Most researchers expect to find that both modes of transition from one species to another are at work in evolution. Slow, continuous change may be the norm during periods of environmental stability, while rapid evolution of new species occurs during periods of environment stress. But a lot more studies like Sheldon' s are needed before we can say for sure.
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The Invention of the Mechanical ClockIn Europe, before the introduction of the mechanical clock, people told time by sun (using, for example, shadow sticks or sun dials) and water clocks. Sun clocks worked, of course, only on clear days; water clocks misbehaved when the temperature fell toward freezing, to say nothing of long-run drift as the result of sedimentation and clogging. Both these devices worked well in sunny climates; but in northern Europe the sun may be hidden by clouds for weeks at a time, while temperatures vary not only seasonally but from day to night.
Medieval Europe gave new importance to reliable time. The Catholic Church had its seven daily prayers, one of which was at night, requiring an alarm arrangement to waken monks before dawn. And then the new cities and towns, squeezed by their walls, had to know and order time in order to organize collective activity and ration space. They set a time to go to sleep,to open the market ,to close the market ,to leave work ,and finally a time to put out fires and to go to sleep. All this was compatible with older devices so long as there was only one authoritative timekeeper; but with urban growth and the multiplication of time signals, discrepancy brought discord and strife. Society needed a more dependable instrument of time measurement and found it in the mechanical clock.
We do not know who invented this machine, or where. It seems to have appeared in Italy and England (perhaps simultaneous invention) between 1275 and 1300. Once known, it spread rapidly, driving out water clocks but not solar dials, which were needed to check the new machines against the timekeeper of last resort. These early versions were rudimentary, inaccurate, and prone to breakdown.
Ironically, the new machine tended to undermine Catholic Church authority. Although church ritual had sustained an interest in timekeeping throughout the centuries of urban collapse that followed the fall of Rome, church time was nature’ s time. Day and night were divided into the same number of parts, so that except at the equinoxes, days and night hours were unequal; and then of course the length of these hours varied with the seasons. But the mechanical clock kept equal hours, and this implied a new time reckoning. The Catholic Church resisted, not coming over to the new hours for about a century. From the start, however, the towns and cities took equal hours as their standard, and the public clocks installed in town halls and market squares became the very symbol of a new, secular municipal authority. Every town wanted one; conquerors seized them as especially precious spoils of war; tourists came to see and hear these machines the way they made pilgrimages to sacred relics.
The clock was the greatest achievement of medieval mechanical ingenuity. Its general accuracy could be checked against easily observed phenomena, like the rising and setting of the sun. The result was relentless pressure to improve technique and design. At every stage, clockmakers led the way to accuracy and precision; they became masters of miniaturization, detectors and correctors of error, searchers for new and better. They were thus the pioneers of mechanical engineering and served as examples and teachers to other branches of engineering.
The clock brought order and control, both collective and personal. Its public display and private possession laid the basis for temporal autonomy: people could now coordinate comings and goings without dictation from above. The clock provided the punctuation marks for group activity, while enabling individuals to order their own work (and that of others) so as to enhance productivity. Indeed, the very notion of productivity is a by-product of the clock: once one can relate performance to uniform time units, work is never the same. One moves from the task-oriented time consciousness of the peasant (working on job after another, as time and light permit) and the time-filling busyness of the domestic servant (who always had something to do) to an effort to maximize product per unit of time.
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Speciation in Geographically Isolated PopulationsEvolutionary biologists believe that speciation, the formation of a new species, often begins when some kind of physical barrier arises and divides a population of a single species into separate subpopulations. Physical separation between subpopulations promotes the formation of new species because once the members of one subpopulation can no longer mate with members of another subpopulation, they cannot exchange variant genes that arise in one of the subpopulations. In the absence of gene flow between the subpopulations, genetic differences between the groups begin to accumulate. Eventually the subpopulations become so genetically distinct that they cannot interbreed even if the physical barriers between them were removed. At this point the subpopulations have evolved into distinct species. This route to speciation is known as allopatry (“allo-” means “different”, and “patria” means “homeland”).
Allopatric speciation may be the main speciation route. This should not be surprising, since allopatry is pretty common. In general, the subpopulations of most species are separated from each other by some measurable distance. So even under normal situations the gene flow among the subpopulations is more of an intermittent trickle than a steady stream. In addition, barriers can rapidly arise and shut off the trickle. For example, in the 1800s a monstrous earthquake changed the course of the Mississippi River, a large river flowing in the central part of the United States of America. The change separated populations of insects now living along opposite shores, completely cutting off gene flow between them.
Geographic isolation can also proceed slowly, over great spans of time. We find evidence of such extended events in the fossil record, which affords glimpse into the breakup of formerly continuous environments. For example, during past ice ages, glaciers advanced down through North America and Europe and gradually cut off parts of populations from one another. When the glaciers retreated, the separated populations of plants and animals came into contact again. Some groups that had descended from the same parent population were no longer reproductively compatible – they had evolved into separate species. In other groups, however, genetic divergences had not proceeded so far, and the descendants could still interbreed – for them, reproductive isolation was not completed, and so speciation had not occurred.
Allopatric speciation can also be brought by the imperceptibly slow but colossal movements of the tectonic plates that make up Earth’s surface. About 5 million years ago such geologic movements created the land bridge between North America and South America that we call the Isthmus of Panama . While previously the gap between the continents had allowed a free flow of water, now the isthmus presented a barrier that divided the Atlantic Ocean from the Pacific Ocean. This division set the stage for allopatric speciation among populations of fishes and other marine species.
In the 1980s, John Graves studied two populations of closely related fishes, one population from the Atlantic side of isthmus, the other from the Pacific side. He compared four enzymes found in the muscles of each population. Graves found that all four Pacific enzymes function better at lower temperatures than the four Atlantic versions of the same enzymes. This is significant because Pacific seawater is typically 2 to 3 degrees cooler than seawater on the Atlantic side of isthmus. Analysis by gel electrophoresis revealed slight differences in amino acid sequence of the enzymes of two of the four pairs. This is significant because the amino acid sequence of an enzyme is determined by genes.
Graves drew two conclusions from these observations. First, at least some of the observed differences between the enzymes of the Atlantic and Pacific fish populations were not random but were the result of evolutionary adaptation. Second, it appears that closely related populations of fishes on both sides of the isthmus are starting to genetically diverge from each other. Because Graves’ study of geographically isolated populations of isthmus fishes offers a glimpse of the beginning of a process of gradual accumulation of mutations that are neutral or adaptive, divergences here might be evidence of allopatric speciation in process.
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Early Childhood EducationPreschools – educational programs for children under the age of five – differ significantly from one country to another according to the views that different societies hold regarding the purpose of early childhood education. For instance, in a cross-country comparison of preschools in China, Japan, and the United States, researchers found that parents in the three countries view the purpose of preschools very differently. Whereas parents in China tend to see preschools primarily as a way of giving children a good start academically, Japanese parents view them primarily as a way of giving children the opportunity to be members of a group. In the United States, in comparison, parents regard the primary purpose of preschools as making children more independent and self-reliant, although obtaining a good academic start and having group experience are also important.
While many programs designed for preschoolers focus primarily on social and emotional factors, some are geared mainly toward promoting cognitive gains and preparing preschoolers for the formal instruction they will experience when they start kindergarten. In the United States, the best-known program designed to promote future academic success is Head Start. Established in the 1960s when the United States declared the War on Poverty, the program has served over 13 million children and their families. The program, which stresses parental involvement, was designed to serve the “whole child”, including children’s physical health, self-confidence, social responsibility, and social and emotional development.
Whether Head Start is seen as successful or not depends on the lens through which one is looking. If, for instance, the program is expected to provide long-term increases in IQ (intelligence quotient) scores, it is a disappointment. Although graduates of Head Start programs tend to show immediate IQ gains, these increases do not last. On the other hand, it is clear that Head Start is meeting its goal of getting preschoolers ready for school. Preschoolers who participate in Head Start are better prepared for future schooling than those who do not. Furthermore, graduates of Head Start programs have better future school grade. Finally, some research suggests that ultimately Head Start graduates show higher academic performance at the end of high school, although the gains are modest.
In addition, results from other types of preschool readiness programs indicate that those who participate and graduate are less likely to repeat grades, and they are more likely to complete school than readiness program, for every dollar spent on the program, taxpayers saved seven dollars by the time the graduates reached the age of 27.
The most recent comprehensive evaluation of early intervention programs suggests that, taken as a group, preschool programs can provide significant benefits, and that government funds invested early in life may ultimately lead to a reduction in future costs. For instance, compared with children who did not participate in early intervention programs, participants in various programs showed gains in emotional or cognitive development, better educational outcomes, increased economic self-sufficiency, reduced levels of criminal activity, and improved health-related behaviors. Of course, not every program produced all these benefits, and not every child benefited to the same extent. Furthermore, some researchers argue that less-expensive programs are just as good as relatively expensive ones, such as Head Start. Still, the results of the evaluation were promising, suggesting that the potential benefits of early intervention can be substantial.
Not everyone agrees that programs that seek to enhance academic skills during the preschool years are a good thing. In fact, according to developmental psychologist David Elkind, United States society tends to push children so rapidly that they begin to feel stress and pressure at a young age. Elkind argues that academic success is largely dependent upon factors out of parents’ control, such as inherited abilities and a child’s rate of maturation. Consequently, children of a particular age cannot be expected to master educational material without taking into account their current level of cognitive development. In short, children require development appropriate educational practice, which is education that is based on both typical development and the unique characteristics of a given child.
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Savanna FormationLocated in tropical areas at low altitudes, savannas are stable ecosystems, some wet and some dry consisting of vast grasslands with scattered trees and shrubs. They occur on a wide range of soil types and in extremes of climate. There is no simple or single factor that determines if a given site will be a savanna, but some factors seem to play important roles in their formation.
Savannas typically experience a rather prolonged dry season. One theory behind savanna formation is that wet forest species are unable to withstand the dry season, and thus savanna, rather than rain forest, is favored on the site. Savannas experience an annual rainfall of between 1,000 and 2,000 millimeters, most of it falling in a five- to eight-month wet season. Though plenty of rain may fall on a savanna during the year, for at least part of the year little does, creating the drought stress ultimately favoring grasses. Such conditions prevail throughout much of northern South America and Cuba, but many Central American savannas as well as coastal areas of Brazil and the island of Trinidad do not fit this pattern. In these areas, rainfall per month exceeds that in the above definition, so other factors must contribute to savanna formation.
In many characteristics, savanna soils are similar to those of some rain forests, though more extreme. For example, savanna soils, like many rain forest soils, are typically oxisols (dominated by certain oxide minerals) and ultisols (soils containing no calcium carbonate), with a high acidity and notably low concentrations of such minerals as phosphorus, calcium, magnesium, and potassium, while aluminum levels are high. Some savannas occur on wet, waterlogged soils; others on dry, sandy, well-drained soils. This may seem contradictory, but it only means that extreme soil conditions, either too wet or too dry for forests, are satisfactory for savannas. More moderate conditions support moist forests.
Waterlogged soils occur in areas that are flat or have poor drainage. These soils usually contain large amounts of clay and easily become water saturated. Air cannot penetrate between the soil particles, making the soil oxygen-poor. By contrast, dry soils are sandy and porous, their coarse textures permitting water to drain rapidly. Sandy soils are prone to the leaching of nutrients and minerals and so tend to be nutritionally poor. Though most savannas are found on sites with poor soils (because of either moisture conditions or nutrient levels of both), poor soils can and do support lush rain forest.
Most savannas probably experience mild fires frequently and major burns every two years or so. Many savanna and dry-forest plant species are called pyrophytes, meaning they are adapted in various ways to withstand occasional burning. Frequent fire is a factor to which rain forest species seem unable to adapt, although ancient charcoal remains from Amazon forest soils dating prior to the arrival of humans suggest that moist forests also occasionally burn. Experiments suggest that if fire did not occur in savannas in the Americas, species composition would change significantly. When burning occurs, it prevents competition among plant species from progressing to the point where some species exclude others, reducing the overall diversity of the ecosystem. But in experimental areas protected from fire, a few perennial grass species eventually come to dominate, outcompeting all others. Evidence from other studies suggests that exclusion of fire results in markedly decreased plant-species richness, often with an increase in tree density. There is generally little doubt that fire is a significant factor in maintaining savanna, certainly in most regions.
On certain sites, particularly in South America, savanna formation seems related to frequent cutting and burning of moist forests for pastureland. Increase in pastureland and subsequent overgrazing have resulted in an expansion of savanna. The thin thin upper layer of humus (decayed organic matter) is destroyed by cutting and burning. Humus is necessary for rapid decomposition of leaves by bacteria and fungi and for recycling by surface roots. Once the humus layer disappears, nutrients cannot be recycled and leach from the soil, converting soil from fertile to infertile and making it suitable only for savanna vegetation. Forests on white, sandy soil are most susceptible to permanent alteration.
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Plant ColonizationColonization is one way in which plants can change the ecology of a site. Colonization is a process with two components: invasion and survival. The rate at which a site is colonized by plants depends on both the rate at which individual organisms (seeds, spores, immature or mature individuals) arrive at the site and their success at becoming established and surviving. Success in colonization depends to a great extent on there being a site available for colonization – a safe site where disturbance by fire or by cutting down of trees has either removed competing species or reduced levels of competition and other negative interactions to a level at which the invading species can become established. For a given rate of invasion, colonization of a moist, fertile site is likely to be much more rapid than that of a dry, infertile site because of poor survival on the latter. A fertile, plowed field is rapidly invaded by a large variety of weeds, whereas a neighboring construction site from which the soil has been compacted or removed to expose a coarse, infertile parent material may remain virtually free of vegetation for many months or even years despite receiving the same input of seeds as the plowed field.
Both the rate of invasion and the rate of extinction vary greatly among different plant species. Pioneer species – those that occur only in the earliest stages of colonization – tend to have high rates of invasion because they produce very large numbers of reproductive propagules (seeds, spores, and so on) and because they have an efficient means of dispersal (normally, wind)
If colonizers produce short-lived reproductive propagules, then they must produce very large numbers unless they have an efficient means of dispersal to suitable new habitats. Many plants depend on wind for dispersal and produce abundant quantities of small, relatively short-lived seeds to compensate for the fact that wind is not always a reliable means of reaching the appropriate type of habitat. Alternative strategies have evolved in some plants, such as those that produce fewer but larger seeds that are dispersed to suitable sites by birds or small mammals or those that produce long-lived seeds. Many forest plants seem to exhibit the latter adaptation, and viable seeds of pioneer species can be found in large numbers on some forest floors. For example, as many as 1,125 viable seeds per square meter were found in a 100-year-old Douglas fir/western hemlock forest in coastal British Columbia. Nearly all the seeds that had germinated from this seed bank were from pioneer species. The rapid colonization of such sites after disturbance is undoubtedly in part a reflection of the large seed bank on the forest floor.
An adaptation that is well developed in colonizing species is a high degree of variation in germination (the beginning of a seed’s growth). Seeds of a given species exhibit a wide range of germination dates, increasing the probability that at least some of the seeds will germinate during a period of favorable environmental conditions. This is particularly important for species that colonize an environment where there is no existing vegetation to ameliorate climatic extremes and in which there may be great climatic diversity.
Species succession in plant communities, i.e., the temporal sequence of appearance and disappearance of species is dependent on events occurring at different stages in the life history of a species. Variation in rates of invasion and growth plays an important role in determining patterns of succession, especially secondary succession. The species that are first to colonize a site are those that produce abundant seed that is distributed successfully to new sites. Such species generally grow rapidly and quickly dominate new sites, excluding other species with lower invasion and growth rates. The first community that occupies a disturbed area therefore may be composed of species with the highest rate of invasion, whereas the community of the subsequent stage may consist of plants with similar survival rates but lower invasion rates.
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Siam 1851–1910In the late nineteenth century, political and social changes were occurring rapidly in Siam (now Thailand). The old ruling families were being displaced by an evolving centralized government. These families were pensioned off (given a sum of money to live on) or simply had their revenues taken away or restricted; their sons were enticed away to schools for district officers, later to be posted in some faraway province; and the old patron-client relations that had bound together local societies simply disintegrated. Local rulers could no longer protect their relatives and attendants in legal cases, and with the ending in 1905 of the practice of forcing peasant farmers to work part-time for local rulers, the rulers no longer had a regular base for relations with rural populations. The old local ruling families, then, were severed from their traditional social context.
The same situation viewed from the perspective of the rural population is even more complex. According to the government’s first census of the rural population, taken in 1905, there were about thirty thousand villages in Siam. This was probably a large increase over the figure even two or three decades earlier, during the late 1800s. It is difficult to imagine it now, but Siam’s Central Plain in the late 1800s was nowhere near as densely settled as it is today. There were still forests closely surrounding Bangkok into the last half of the nineteenth century, and even at century’s end there were wild elephants and tigers roaming the countryside only twenty or thirty miles away.
Much population movement involved the opening up of new lands for rice cultivation. Two things made this possible and encouraged it to happen. First, the opening of the kingdom to the full force of international trade by the Bowring Treaty (1855) rapidly encouraged economic specialization in the growing of rice, mainly to feed the rice-deficient portions of Asia (India and China in particular). The average annual volume of rice exported from Siam grew from under 60 million kilograms per year in the late 1850s to more than 660 million kilograms per year at the turn of the century; and over the same period the average price per kilogram doubled. During the same period, the area planted in rice increased from about 230,000 acres to more than350,000 acres. This growth was achieve as the result of the collective decisions of thousands of peasants families to expand the amount of land they cultivated, clear and plant new land, or adopt more intensive methods of agriculture.
They were able to do so because of our second consideration. They were relatively freer than they had been half a century earlier. Over the course of the Fifth Reign (1868 – 1910), the ties that bound rural people to the aristocracy and local ruling elites were greatly reduced. Peasants now paid a tax on individuals instead of being required to render labor service to the government. Under these conditions, it made good sense to thousands of peasant families to in effect work full-time at what they had been able to do only part-time previously because of the requirement to work for the government: grow rice for the marketplace.
Numerous changes accompanied these developments. The rural population both dispersed and grew, and was probably less homogeneous and more mobile than it had been a generation earlier. The villages became more vulnerable to arbitrary treatment by government bureaucrats as local elites now had less control over them.By the early twentieth century, as government modernization in a sense caught up with what had been happening in the countryside since the 1870s, the government bureaucracy intruded more and more into village life. Provincial police began to appear, along with district officers and cattle registration and land deeds and registration for compulsory military service. Village handicrafts diminished or died out completely as people bought imported consumer goods, like cloth and tools, instead of making them themselves. More economic variation took shape in rural villages, as some grew prosperous from farming while others did not. As well as can be measured, rural standards of living improved in the Fifth Reign. But the statistical averages mean little when measured against the harsh realities of peasant life.
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Distributions of Tropical Bee ColoniesIn 1977 ecologists Stephen Hubbell and Leslie Johnson recorded a dramatic example of how social interactions can produce and enforce regular spacing in a population. They studied competition and nest spacing in populations of stingless bees in tropical dry forests in Costa Rica. Though these bees do no sting, rival colonies of some species fight fiercely over potential nesting sites.
Stingless bees are abundant in tropical and subtropical environments, where they gather nectar and pollen from a wide variety of flowers. They generally nest in trees and live in colonies made up of hundreds to thousands of workers. Hubbell and Johnson observed that some species of stingless bees are highly aggressive to members of their species from other colonies, while other species are not. Aggressive species usually forage in groups and feed mainly on flowers that occur in high-density clumps. Nonaggressive species feed singly or in small groups and on more widely distributed flowers.
Hubbell and Johnson studied several species of stingless bees to determine whether there is a relationship between aggressiveness and patterns of colony distribution. They predicted that the colonies of aggressive species would show regular distributions, while those of nonaggressive species would show random or closely grouped (clumped) distribution. They concentrated their studies on a thirteen-hectare tract of tropical dry forest that contained numerous nests of nine species of stingless bees.
Though Hubbell and Johnson were interested in how bee behavior might affect colony distributions, they recognized that the availability of potential nest sites for colonies could also affect distributions.So as one of the first steps in their study, they mapped the distributions of trees suitable for nesting. They found that potential nest trees were distributed randomly through the study area. They also found that the number of potential nest sites was much greater than the number of bee colonies. What did these measurements show the researchers? The number of colonies in the study area was not limited by availability of suitable trees, and a clumped or regular distribution of colonies was not due to an underlying clumped or regular distribution of potential nest sites.
Hubbell and Johnson mapped the nests of five of the nine species of stingless bees accurately, and the nests of four of these species were distributed regularly. All four species with regular nest distributions were highly aggressive to bees from other colonies of their own species. The fifth species was not aggressive, and its nests were randomly distributed over the study area.
The researchers also studied the process by which the aggressive species establish new colonies. Their observations provide insights into the mechanisms that establish and maintain the regular nest distribution of these species. Aggressive species apparently mark prospective nest sites with pheromones, chemical substances secreted by some animals for communication with other members of their species. The pheromone secreted by these stingless bees attracts and aggregates members of their colony to the prospective nest site; however, it also attracts workers from other nests.
If workers from two different colonies arrive at the prospective nest at the same time, they may fight for possession. Fights may be escalated into protracted battles.The researchers observed battles over a nest tree that lasted for two weeks. Each dawn, fifteen to thirty workers from two competing colonies arrived at the contested nest site. The workers from the two colonies faced off in two swarms and displayed and fought with each other. In the displays, pairs of bees faced each other, slowly flew vertically to a height of about three meters, and then grappled each other to the ground. When the two bees hit the ground, they separated, faced off, and performed another aerial display. Bees did not appear to be injured in these fights, which were apparently ritualized. The two swarms abandoned the battle at about 8 or 9 A.M. each morning, only to re-form and begin again the next day just after dawn. While this contest over an unoccupied nest site produced no obvious mortality, fights over occupied nests sometimes kill over 1,000 bees in a single battle.
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The First CivilizationsEvidence suggests that an important stimulus behind the rise of early civilizations was the development of settled agriculture, which unleashed a series of changes in the organization of human communities that culminated in the rise of large ancient empires.
The exact time and place that crops were first cultivated successfully is uncertain. Many prehistorians believe that farming may have emerged in dependently in several different areas of the world when small communities, driven by increasing population and a decline in available food resources, began to plant seeds in the ground in an effort to guarantee their survival. The first farmers, who may have lived as long as 10,000 years ago, undoubtedly used simple techniques and still relied primarily on other forms of food production, such as hunting, foraging, or pastoralism. The real breakthrough took place when farmers began to cultivate crops along the floodplains of river systems. The advantage was that crops grown in such areas were not as dependent on rainfall and therefore produced a more reliable harvest. An additional benefit was that the sediment carried by the river waters deposited nutrients in the soil, thus enabling the farmer to cultivate a single plot of ground for many years without moving to a new location. Thus, the first truly sedentary (that is, nonmigratory) societies were born. As time went on, such communities gradually learned how to direct the flow of water to enhance the productive capacity of the land, while the introduction of the iron plow eventually led to the cultivation of heavy soils not previously susceptible to agriculture.
The spread of this river valley agriculture in various parts of Asia and Africa was the decisive factor in the rise of the first civilizations. The increase in food production in these regions led to a significant growth in population, while efforts to control the flow of water to maximize the irrigation of cultivated areas and to protect the local inhabitants from hostile forces outside the community provoked the first steps toward cooperative activities on a large scale. The need to oversee the entire process brought about the emergence of an elite that was eventually transformed into a government.
The first clear steps in the rise of the first civilizations took place in the fourth and third millennia B.C. in Mesopotamia, northern Africa, India, and China. How the first governments took shape in these areas is not certain, but anthropologists studying the evolution of human communities in various parts of the world have discovered that one common stage in the process is the emergence of what are called “big men” within a single village or a collection of villages. By means of their military prowess, dominant personalities, or political talents, these people gradually emerge as the leaders of that community. In time, the “big men” become formal symbols of authority and pass on that authority to others within their own family. As the communities continue to grow in size and material wealth, the “big men” assume hereditary status, and their allies and family members are transformed into a hereditary monarchy.
The appearance of these sedentary societies had a major impact on the social organizations, religious beliefs, and way of life of the peoples living within their boundaries. With the increase in population and the development of centralized authority came the emergence of the cities. While some of these urban centers were identified with a particular economic function, such as proximity to gold or iron deposits or a strategic location on a major trade route, others served primarily as administrative centers or the site of temples for the official cult or other ritual observances. Within these cities, new forms of livelihood appeared to satisfy the growing need for social services and consumer goods. Some people became artisans or merchants, while others became warriors, scholars, or priests. In some cases, the physical division within the first cities reflected the strict hierarchical character of the society as a whole, with a royal palace surrounded by an imposing wall and separate from the remainder of the urban population. In other instances, such as the Indus River Valley, the cities lacked a royal precinct and the ostentatious palaces that marked their contemporaries elsewhere.
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Railroads and Commercial Agriculture in Nineteenth Century United StatesBy 1850 the United States possessed roughly 9,000 miles of railroad track; ten years later it had over 30,000 miles, more than the rest of the world combined. Much of the new construction during the 1850s occurred west of the Appalachian Mountains – over 2,000 miles in the states of Ohio and Illinois alone.
The effect of the new railroad lines rippled outward through the economy. Farmers along the tracks began to specialize in corps that they could market in distant locations. With their profits they purchased manufactured goods that earlier they might have made at home. Before the railroad reached Tennessee, the state produced about 25,000 bushels (or 640 tons) of wheat, which sold for less than 50 cents a bushel. Once the railroad came, farmers in the same counties grew 400,000 bushels (over 10,000 tons) and sold their crop at a dollar a bushel.
The new railroad networks shifted the direction of western trade. In 1840 most northwestern grain was shipped south down the Mississippi River to the bustling port of New Orleans. But low water made steamboat travel hazardous in summer, and ice shut down traffic in winter. Products such as lard, tallow, and cheese quickly spoiled if stored in New Orleans’ hot and humid warehouses. Increasingly, traffic from the Midwest flowed west to east, over the new rail lines. Chicago became the region’s hub, linking the farms of the upper Midwest to New York and other eastern cities by more than 2,000 miles of track in 1855. Thus while the value of goods shipped by river to New Orleans continued to increase, the South’s overall share of western trade dropped dramatically.
A sharp rise in demand for grain abroad also encouraged farmers in the Northeast and Midwest to become more commercially oriented. Wheat, which in 1845 commanded $1.08 a bushel in New York City, fetched $2.46 in 1855; in similar fashion the price of corn nearly doubled. Farmers responded by specializing in cash crops, borrowing to purchase more land, and investing in equipment to increase productivity.
As railroad lines fanned out from Chicago, farmers began to acquire open prairie land in Illinois and then Iowa, putting the fertile, deep black soil into production.Commercial agriculture transformed this remarkable treeless environment. To settlers accustomed to eastern woodlands, the thousands of square miles of tall grass were an awesome sight. Indian grass, Canada wild rye, and native big bluestem all grew higher than a person. Because eastern plows could not penetrate the densely tangled roots of prairie grass, the earliest settlers erected farms along the boundary separating the forest from the prairie. In 1837, however, John Deere patented a sharp-cutting steel plow that sliced through the sod without soil sticking to the blade. Cyrus McCormick refined a mechanical reaper that harvested fourteen times more wheat with the same amount of labor. By the 1850s McCormick was selling 1,000 reapers a year and could not keep up with demand, while Deere turned out 10,000 plows annually.
The new commercial farming fundamentally altered the Midwestern landscape and the environment. Native Americans had grown corn in the region for years, but never in such large fields as did later settlers who became farmers, whose surpluses were shipped east. Prairie farmers also introduced new crops that were not part of the earlier ecological system, notably wheat, along with fruits and vegetables.
Native grasses were replaced by a small number of plants cultivated as commodities. Corn had the best yields, but it was primarily used to feed livestock. Because bread played a key role in the American and European diet, wheat became the major cash crop. Tame grasses replaced native grasses in pastures for making hay.
Western farmers altered the landscape by reducing the annual fires that had kept the prairie free from trees. In the absence of these fires, trees reappeared on land not in cultivation and, if undisturbed, eventually formed woodlots. The earlier unbroken landscape gave way to independent farms, each fenced off in a precise checkerboard pattern. It was an artificial ecosystem of animals, woodlots, and crops, whose large, uniform layout made western farms more efficient than the more-irregular farms in the East.
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Extinction Episodes of the PastIt was not until the Cambrian period, beginning about 600 million years ago, that a great proliferation of macroscopic species occurred on Earth and produced a fossil record that allows us to track the rise and fall of biodiversity. Since the Cambrian period, biodiversity has generally risen, but there have been some notable exceptions. Biodiversity collapsed dramatically during at least five periods because of mass extinctions around the globe. The five major mass extinctions receive most of the attention, but they are only one end of a spectrum of extinction events.Collectively, more species went extinct during smaller events that were less dramatic but more frequent. The best known of the five major extinction events, the one that saw the demise of the dinosaurs, is the Cretaceous-Tertiary extinction.
Starting about 280 million years ago, reptiles were the dominant large animals in terrestrial environments. In popular language this was the era “when dinosaurs ruled Earth,” when a wide variety of reptile species occupying many ecological niches. However, no group or species can maintain its dominance indefinitely, and when, after over 200 million years, the age of dinosaurs came to a dramatic end about 65 million years ago, mammals began to flourish, evolving from relatively few types of small terrestrial animals into the myriad of diverse species, including bats and whales, that we know today. Paleontologists label this point in Earth’s history as the end of the Cretaceous period and the beginning of the Tertiary period, often abbreviated as the K-T boundary. This time was also marked by changes in many other types of organisms. Overall, about 38 percent of the families of marine animals were lost, with percentages much higher in some groups Ammonoid mollusks went from being very diverse and abundant to being extinct. An extremely abundant set of planktonic marine animals called foraminifera largely disappeared, although they rebounded later. Among plants, the K-T boundary saw a sharp but brief rise in the abundance of primitive vascular plants such as ferns, club mosses, horsetails, and conifers and other gymnosperms. The number of flowering plants (angiosperms) was reduced at this time, but they then began to increase dramatically.
What caused these changes? For many years scientists assumed that a cooling of the climate was responsible, with dinosaurs being particularly vulnerable because, like modern reptiles, they were ectothermic (dependent on environmental heat, or cold-blooded). It is now widely believed that at least some species of dinosaurs had a metabolic rate high enough for them to be endotherms (animals that maintain a relatively consistent body temperature by generating heat internally). Nevertheless, climatic explanations for the K-T extinction are not really challenged by the ideas that dinosaurs may have been endothermic, because even endotherms can be affected by a significant change in the climate.
Explanations for the K-T extinction were revolutionized in 1980 when a group of physical scientists led by Luis Alvarez proposed that 65 million years ago Earth was stuck by a 10-kilometer-wide meteorite traveling at 90,000 kilometers per hour. They believed that this impact generated a thick cloud of dust that enveloped Earth, shutting out much of the incoming solar radiation and reducing plant photosynthesis to very low levels. Short-term effects might have included huge tidal waves and extensive fires. In other words, a series of events arising from a single cataclysmic event caused the massive extinctions. Initially, the meteorite theory was based on a single line of evidence. At locations around the globe, geologists had found an unusually high concentration of iridium in the layer of sedimentary rocks that was formed about 65 million years ago. Iridium is an element that is usually uncommon near Earth’s surface, but it is abundant in some meteorites.Therefore, Alvarez and his colleagues concluded that it was likely that the iridium in sedimentary rocks deposited at the K-T boundary had originated in a giant meteorite or asteroid. Most scientist came to accept the meteorite theory after evidence came to light that a circular formation, 180 kilometers in diameter and centered on the north coast of the Yucatan Peninsula, was created by a meteorite impact about 65 million years ago.
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Islamic Art and the BookThe arts of the Islamic book, such as calligraphy and decorative drawing, developed during A.D. 900 to 1500, and luxury books are some of the most characteristic examples of Islamic art produced in this period. This came about from two major developments: paper became common, replacing parchment as the major medium for writing, and rounded scripts were regularized and perfected so that they replaced the angular scripts of the previous period, which because of their angularity were uneven in height. Books became major vehicles for artistic expression, and the artists who produced them, notably calligraphers and painters, enjoyed high status, and their workshops were often sponsored by princes and their courts. Before A.D. 900, manuscripts of the Koran (the book containing the teachings of the Islamic religion) seem to have been the most common type of book produced and decorated, but after that date a wide range of books were produced for a broad spectrum of patrons. These continued to include, of course, manuscripts of the Koran, which every Muslim wanted to read, but scientific works, histories, romances, and epic and lyric poetry were also copied in fine handwriting and decorated with beautiful illustrations. Most were made for sale on the open market, and cities boasted special souks (markets) where books were bought and sold. The mosque of Marrakech in Morocco is known as the Kutubiyya, or Booksellers’ Mosque, after the adjacent market. Some of the most luxurious books were specific commissions made at the order of a particular prince and signed by the calligrapher and decorator.
Papermaking had been introduced to the Islamic lands from China in the eighth century. It has been said that Chinese papermakers were among the prisoners captured in a battle fought near Samarqand between the Chinese and the Muslims in 751, and the technique of papermaking – in which cellulose pulp extracted from any of several plants is first suspended in water, caught on a fine screen, and then dried into flexible sheets – slowly spread westward. Within fifty years, the government in Baghdad was using paper for documents. Writing in ink on paper, unlike parchment, could not easily be erased, and therefore paper had the advantage that it was difficult to alter what was written on it. Papermaking spread quickly to Egypt – and eventually to Sicily and Spain – but it was several centuries before paper supplanted parchment for copies of the Koran, probably because of the conservative nature of religious art and its practitioners. In western Islamic lands, parchment continued to be used for manuscripts of the Koran throughout this period.
The introduction of paper spurred a conceptual revolution whose consequences have barely been explored. Although paper was never as cheap as it has become today, it was far less expensive than parchment, and therefore more people could afford to buy books, Paper is thinner than parchment, so more pages could be enclosed within a single volume. At first, paper was made in relatively small sheets that were pasted together, but by the beginning of the fourteenth century, very large sheets – as much as a meter across – were available.These large sheets meant that calligraphers and artists had more space on which to work. Paintings became more complicated, giving the artist greater opportunities to depict space or emotion. The increased availability of paper, particularly after 1250, encouraged people to develop systems of representation, such as architectural plans and drawings. This in turn allowed the easy transfer of artistic ideas and motifs over great distances from one medium to another, and in a different scale in ways that had been difficult, if not impossible, in the previous period.
Rounded styles of Arabic handwriting had long been used for correspondence and documents alongside the formal angular scripts used for inscriptions and manuscripts of the Koran. Around the year 900, Ibn Muqla, who was a secretary and vizier at the Abbasid court in Baghdad, developed a system of proportioned writing. He standardized the length of alif, the first letter of the Arabic alphabet, and then determined what the size and shape of all other letters should be, based on the alif. Eventually, six round forms of handwriting, composed of three pairs of big and little scripts known collectively as the Six Pens, became the standard repertory of every calligrapher.
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The Development of Steam PowerBy the eighteenth century, Britain was experiencing a severe shortage of energy. Because of the growth of population, most of the great forests of medieval Britain had long ago been replaced by fields of grain and hay. Wood was in ever-shorter supply, yet it remained tremendously important. It served as the primary source of heat for all homes and industries and as a basic raw material. Processed wood (charcoal) was the fuel that was mixed with iron ore in the blast furnace to produce pig iron (raw iron). The iron industry’s appetite for wood was enormous, and by 1740 the British iron industry was stagnating. Vast forests enabled Russia to become the world’s leading producer of iron, much of which was exported to Britain. But Russia’s potential for growth was limited too, and in a few decades Russia would reach the barrier of inadequate energy that was already holding England back.
As this early energy crisis grew worse, Britain looked toward its abundant and widely scattered reserves of coal as an alternative to its vanishing wood. Coal was first used in Britain in the late Middle Ages as a source of heat. By 1640 most homes in London were heated with it, and it also provided heat for making beer, glass, soap, and other products. Coal was not used, however, to produce mechanical energy or to power machinery. It was there that coal’s potential wad enormous.
As more coal was produced, mines were dug deeper and deeper and were constantly filling with water. Mechanical pumps, usually powered by hundreds of horses waling in circles at the surface, had to be installed. Such power was expensive and bothersome. In an attempt to overcome these disadvantages, Thomas Savery in 1698 and Thomas Newcomen in 1705 invented the first primitive steam engines. Both engines were extremely inefficient. Both burned coal to produce steam, which was then used to operate a pump. However, by the early 1770s, many of the Savery engines and hundreds of the Newcomen engines were operating successfully, though inefficiently, in English and Scottish mines.
In the early 1760s, a gifted young Scot named James Watt was drawn to a critical study of the steam engine. Watt was employed at the time by the University of Glasgow as a skilled crafts worker making scientific instruments. In 1763, Watt was called on to repair a Newcomen engine being used in a physics course. After a series of observations, Watt saw that the New comen’s waste of energy could be reduced by adding a separate condenser. This splendid invention, patented in 1769, greatly increased the efficiency of the steam engine. The steam engine of Watt and his followers was the technological advance that gave people, at least for a while, unlimited power and allowed the invention and use of all kinds of power equipment.
The steam engine was quickly put to use in several industries in Britain. It drained mines and made possible the production of ever more coal to feed steam engines elsewhere. The steam power plant began to replace waterpower in the cotton-spinning mills as well as other industries during the 1780s, contributing to a phenomenal rise in industrialization. The British iron industry was radically transformed. The use of powerful, steam-driven bellows in blast furnaces helped iron makers switch over rapidly from limited charcoal to unlimited coke (which is made from coal) in the smelting of pig iron (the process of refining impure iron) after 1770 in the 1780s, Henry Cort developed the puddling furnace, which allowed pig iron to be refined in turn with coke. Cort also developed heavy-duty, steam-powered rolling mills, which were capable of producing finished iron in every shape and form.
The economic consequence of these technical innovations in steam power was a great boom in the British iron industry. In 1740 annual British iron production was only 17,000 tons, but by 1844, with the spread of coke smelting and the impact of Cort’s inventions, it had increased to 3,000,000 tons. This was a truly amazing expansion. Once scarce and expensive, iron became cheap, basic, and indispensable to the economy.
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Protection of Plants by InsectsMany plants – one or more species of at least 68 different families – can secrete nectar even when they have no blossoms, because they bear extrafloral nectaries (structures that produce nectar) on stems, leaves, leaf stems, or other structures. These plants usually occur where ants are abundant, most in the tropics but some in temperate areas. Among those of northeastern North America are various plums, cherries, roses, hawthorns, poplars, and oaks. Like floral nectar, extrafloral nectar consists mainly of water with a high content of dissolved sugars and, in some plants, small amounts of amino acids. The extrafloral nectaries of some plants are known to attract ants and other insects, but the evolutionary history of most plants with these nectaries is unknown. Nevertheless, most ecologists believe that all extrafloral nectaries attract insects that will defend the plant.
Ants are portably the most frequent and certainly the most persistent defenders of plants. Since the highly active worker ants require a great deal of energy, plants exploit this need by providing extrafloral nectar that supplies ants with abundant energy. To return this favor, ants guard the nectaries, driving away or killing intruding insects that might compete with ants for nectar. Many of these intruders are herbivorous and would eat the leaves of the plants.
Biologists once thought that secretion of extrafloral nectar has some purely internal physiological function, and that ants provide no benefit whatsoever to the plants that secrete it. This view and the opposing “protectionist” hypothesis that ants defend plants had been disputed for over a hundred years when, in 1910, a skeptical William Morton Wheeler commented on the controversy. He called for proof of the protectionist view: that visitations of the ants confer protection on the plants and that in the absence of the insects a much greater number would perish or fail to produce flowers or seeds than when the insects are present. That we now have an abundance of the proof that was called for was established when Barbara Bentley reviewed the relevant evidence in 1977, and since then many more observations and experiments have provided still further proof that ants benefit plants.
One example shows how ants attracted to extrafloral nectaries protect morning glories against attacking insects. The principal insect enemies of the North American morning glory feed mainly on its flowers or fruits rather than its leaves. Grasshoppers feeding on flowers indirectly block pollination and the production of seeds by destroying the corolla or the stigma, which receives the pollen grains and on which the pollen germinates. Without their colorful corolla, flowers do not attract pollinators and are not fertilized. An adult grasshopper can consume a large corolla, about 2.5 inches long, in an hour. Caterpillars and seed beetles affect seed production directly. Caterpillars devour the ovaries, where the seeds are produced, and seed beetle larvae eat seeds as they burrow in developing fruits.
Extrafloral nectaries at the base of each sepal attract several kinds of insects, but 96 percent of them are ants, several different species of them. When buds are still small, less than a quarter of an inch long, the sepal nectaries are already present and producing nectar. They continue to do so as the flower develops and while the fruit matures. Observations leave little doubt that ants protect morning glory flowers and fruits from the combined enemy force of grasshoppers, caterpillars, and seed beetles. Bentley compares the seed production of six plants that grew where there were no ants with that of seventeen plants that were occupied by ants. Unprotected plants bore only 45 seeds per plant, but plants occupied by ants bore 211 seeds per plant. Although ants are not big enough to kill or seriously injure grasshoppers, they drive them away by nipping at their feet. Seed beetles are more vulnerable because they are much smaller than grasshoppers. The ants prey on the adult beetles, disturb females as they lay their eggs on developing fruits, and eat many of the eggs they do manage to lay.
R35P1
"Earth's AgeOne of the first recorded observers to surmise a long age for Earth was the Greek historian Herodotus, who lived from approximately 480 B.C. to 425 B.C. He observed that the Nile River Delta was in fact a series of sediment deposits built up in successive floods. By noting that individual floods deposit only thin layers of sediment, he was able to conclude that the Nile Delta had taken many thousands of years to build up. More important than the amount of time Herodotus computed, which turns out to be trivial compared with the age of Earth, was the notion that one could estimate ages of geologic features by determining rates of the processes responsible for such features, and then assuming the rates to be roughly constant over time. Similar applications of this concept were to be used again and again in later centuries to estimate the ages of rock formations and, in particular, of layers of sediment that had compacted and cemented to form sedimentary rocks.
It was not until the seventeenth century that attempts were made again to understand clues to Earth's history through the rock record. Nicolaus Steno (1638-1686) was the first to work out principles of the progressive depositing of sediment in Tuscany. However, James Hutton (1726-1797), known as the founder of modern geology, was the first to have the important insight that geologic processes are cyclic in nature. Forces associated with subterranean heat cause land to be uplifted into plateaus and mountain ranges. The effects of wind and water then break down the masses of uplifted rock, producing sediment that is transported by water downward to ultimately form layers in lakes, seashores, or even oceans. Over time, the layers become sedimentary rock. These rocks are then uplifted sometime in the future to form new mountain ranges, which exhibit the sedimentary layers (and the remains of life within those layers) of the earlier episodes of erosion and deposition.
Hutton's concept represented a remarkable insight because it unified many individual phenomena and observations into a conceptual picture of Earth's history. With the further assumption that these geologic processes were generally no more or less vigorous than they are today, Hutton's examination of sedimentary layers led him to realize that Earth's history must be enormous, that geologic time is an abyss and human history a speck by comparison.
After Hutton, geologists tried to determine rates of sedimentation so as to estimate the age of Earth from the total length of the sedimentary or stratigraphic record. Typical numbers produced at the turn of the twentieth century were 100 million to 400 million years. These underestimated the actual age by factors of 10 to 50 because much of the sedimentary record is missing in various locations and because there is a long rock sequence that is older than half a billion years that is far less well defined in terms of fossils and less well preserved.
Various other techniques to estimate Earth's age fell short, and particularly noteworthy in this regard were flawed determinations of the Sun's age. It had been recognized by the German philosopher Immanuel Kant (1724-1804) that chemical reactions could not supply the tremendous amount of energy flowing from the Sun for more than about a millennium. Two physicists during the nineteenth century both came up with ages for the Sun based on the Sun's energy coming from gravitational contraction. Under the force of gravity, the compression resulting from a collapse of the object must release energy. Ages for Earth were derived that were in the tens of millions of years, much less than the geologic estimates of the lime.
It was the discovery of radioactivity at the end of the nineteenth century that opened the door to determining both the Sun's energy source and the age of Earth. From the initial work came a suite of discoveries leading to radio isotopic dating, which quickly ted to the realization that Earth must be billions of years old, and to the discovery of nuclear fusion as an energy source capable of sustaining the Sun's luminosity for that amount of time. By the 1960s, both analysis of meteorites and refinements of solar evolution models converged on an age for the solar system, and hence for Earth, of 4 5 billion years. "
R35P2
"The Development of Social ComplexityFor most of human history, we have foraged (hunted, fished, and collected wild plants) for food. Small nomadic groups could easily supply the necessities for their families. No one needed more, and providing for more than one's needs made little sense. The organization of such societies could be rather simple, revolving around age and gender categories. Such societies likely were largely egalitarian, beyond distinctions based on age and gender, virtually all people had equivalent rights, status, and access to resources.
Archaeologist Donald Henry suggests that the combination of a rich habitat and sedentism (permanent, year-round settlement) led to a dramatic increase in human population. In his view, nomadic, simple foragers have relatively tow levels of fertility. Their high-protein, low-carbohydrate diets result in low body-fat levels, which are commonly associated with low fertility in women. High levels of physical activity and long periods of nursing, which are common among modern simple foragers, probably also contributed to low levels of female fertility if they were likewise common among ancient foragers.
In Henry's view, the adoption of a more settled existence in areas with abundant food resources would have contributed to higher fertility levels among the sedentary foragers. A diet higher in wild cereals produces proportionally more body fat, leading to higher fertility among women. Cereals, which are easy to digest, would have supplemented and then replaced mother's milk as the primary food for older infants. Since women are less fertile when they are breast-feeding, substituting cereals for mother smilk would have resulted in closer spacing of births and the potential for a greater number of live births for each woman. A more sedentary existence may also have lowered infant mortality and perhaps increased longevity among the aged. These more vulnerable members of society could safely stay in a fixed village rather than be forced regularly to move great distances as part of a nomadic existence, with its greater risk of accidents and trauma.
All of these factors may have resulted in a trend of increasing size among some local human populations in the Holocene (since 9600 B C E ). Given sufficient time, even in very rich habitats, human population size can reach carrying capacity, the maximum population an area can sustain within the context of a given subsistence system. And human population growth is like a runaway tram once it picks up speed, it is difficult to control. So even after reaching an area's carrying capacity, Holocene human populations probably continued to grow in food-rich regions, overshooting the ability of the territory to feed the population, again within the context of the same subsistence strategy. In some areas, small changes in climate or minor changes in plant characteristics may have further destabilized local economies.
One possible response to surpassing the carrying capacity of a region is for a group to exploit adjoining land. However, good land may itself be limited-for example, within the confines of a river valley where neighbors are in the same position, having filled up the whole of the desirable habitat available in their home territories, expansion is also problematic. Impinging on the neighbors' territory can lead to conflict, especially when they too are up against the capacity of the land to provide enough food.
Another option is to stay in the same area but to shift and intensify the food quest there. The impulse to produce more food to feed a growing population was satisfied in some areas by the development of more-complex subsistence strategies involving intensive labor and requiring more cooperation and greater coordination among the increasing numbers of people. This development resulted in a change in the social and economic equations that defined those societies. Hierarchies that did not exist in earlier foraging groups but that were helpful in structuring cooperative labor and in organizing more-complex technologies probably became established, even before domestication and agriculture, as pre-Neolithic societies (before the tenth millennium B C E) reacted to the population increase. "
R35P3
"Seasonal Succession In PhytoplankonPhytoplankton are minute free-floating aquatic plants. In addition to the marked changes in abundance observed in phytoplankton over the course of a year, there is also a marked change in species composition. This change in the dominant species from season to season is called seasonal succession, and it occurs in a wide variety of locations. Under seasonal succession, one or more species dominate the phytoplankton for a shorter or longer period of time and then are replaced by another set of species. This pattern is repeated yearly. This succession is different from typical terrestrial ecological succession in which various plants replace one another until finally a so-called climax community develops, which persists for many years.
What are the factors causing this phenomenon? Considering that seasonal succession is most often and clearly seen in temperate seas, which have a marked change in temperature during a year, temperature has been suggested as a cause. This may be one of the factors, but it is unlikely to be the sole cause because there are species that become dominant species at various temperatures. Furthermore, temperature changes rather slowly in seawater, and the replacement of dominant species often is much more rapid.
Another suggested reason is the change in nutrient level over the year, with differing concentrations favoring different phytoplanklon species. While this factor may also contribute, observations suggest that phytoplankton populations rise and fall much more quickly than nutrient concentrations change.
Yet another explanation is that species succession is a consequence of changes in seawater brought about by the phytoplankton living in it. Each species of phytoplankton secretes or excretes organic molecules into the seawater. These metabolites can have an effect on the organisms living in the seawater, either inhibiting or promoting their growth. For any individual organism, the amount of metabolite secreted is small. But the effect of secretions by all the individuals of the dominant species can be significant both for themselves and for other species.
These organic metabolites could, and probably do, include a number of different classes of organic compounds. Some are likely toxins, such as those released by the dinoflagellates (a species of plankton) during red tides, which inhibit growth of other photosynthetic organisms. In such cases, the population explosion of dinoflagellates is so great that the water becomes brownish red in color from the billions of dinoflagellate cells. Although each cell secretes a minute amount of toxin, the massive dinoflagellate numbers cause the toxin to reach concentrations that kill many creatures. This toxin can be concentrated in such filter-feeding organisms as clams and mussels, rendering them toxic to humans.
Another class of metabolite is the vitamins. It is now known that certain phytoplankton species have requirements for certain vitamins, and that there are considerable differences among species as to requirements. The B vitamins, especially vitamin B12, thiamine and biotin, seem to be the most generally required. Some species may be unable to thrive until a particular vitamin, or group of vitamins, is present in the water. These vitamins are produced only by another species: hence, a succession of species could occur whereby first the vitamin-producing species is present and then the vitamin-requiring species follows.
Other organic compounds that may inhibit or promote various species include amino acids, carbohydrates, and fatty acids. Although it is suspected that these organic metabolites may have an important role in species succession and it has been demonstrated in the laboratory that phytoplankton species vary both in their ability to produce necessary vitamins and in their requirements for such in order to grow, evidence is still inadequate as to their real role in the sea.
There is also evidence to suggest that grazers (animals that feed on plants or stationary animals), particularly selective grazers, can influence the phytoplankton species composition. Many copepods (small, herbivorous crustaceans) and invertebrate larvae pick out selected phytoplankton species from mixed groups, changing the species composition.
A growing body of evidence now suggests that all of the factors considered here are operating simultaneously to produce species succession. The importance of any factor will vary with the particular phytoplankton species and the environmental conditions. "
R36P1
"Soil FormationLiving organisms play an essential role in soil formation. The numerous plants and animals living in the soil release minerals from the parent material from which soil is formed, supply organic matter, aid in the translocation (movement) and aeration of the soil, and help protect the soil from erosion. The types of organisms growing or living in the soil greatly influence the soil's physical and chemical characteristics. In fact, for mature soils in many parts of the world, the predominant type of natural vegetation is considered the most important direct influence on soil characteristics. For this reason, a soil scientist can tell a great deal about the attributes of the soil in any given area simply form knowing what kind of flora the soil supports. Thus prairies and tundra regions, which have characteristic vegetations, also have characteristic soils.
The quantity and total weight of soil flora generally exceed that of soil fauna. By far the most numerous and smallest of the plants living in soil are bacteria. Under favorable conditions, a million or more of these tiny, single-celled plants can inhabit each cubic centimeter of soil. It is the bacteria, more than any other organisms, that enable rock or other parent material to undergo the gradual transformation to soil. Some bacteria produce organic acids that directly attack parent material, breaking it down and releasing plant nutrients. Others decompose organic litter (debris) to form humus (nutrient-rich organic matter). A third group of bacteria inhabits the root systems of plants called legumes. These include many important agricultural crops, such as alfalfa, clover, soybeans, peas, and peanuts. The bacteria that legumes host within their root nodules (small swellings on the root) change nitrogen gas from the atmosphere into nitrogen compounds that plants are able to metabolize, a process, known as nitrogen fixation, that makes the soil more fertile. Other microscopic plants also are important in soil development. For example, in highly acidic soils where few bacteria can survive, fungi frequently become the chief decomposers of organic matter.
More complex forms of vegetation play several vital roles with respect to the soil. Tress, grass, and other large plants supply the bulk of the soil's humus. The minerals released as these plants decompose on the surface constitute an important nutrient source for succeeding generations of plants as well as for other soil organisms. In addition, trees can extend their roots deep within the soil and bring up nutrients from far below the surface. These nutrients eventually enrich the surface soil when the tree drops its leaves or when it dies and decomposes. Finally, trees perform the vital function of slowing water runoff and holding the soil in place with their root systems, thus combating erosion. The increased erosion that often accompanies agricultural use of sloping land is principally caused by the removal of its protective cover of natural vegetation.
Animals also influence soil composition. The faunal counterparts of bacteria are protozoa. These single-celled organisms are the most numerous representatives of the animal kingdom, and, like bacteria, a million or more can sometimes inhabit each cubic centimeter of soil. Protozoa feed on organic matter and hasten its decomposition. Among other soil-dwelling animals, the earthworm is probably the most important. Under exceptionally favorable conditions, up to a million earthworms (with a total body weight exceeding 450 kilograms) may inhabit an acre of soil. Earthworms ingest large quantities of soil, chemically alter it, and excrete it as organic matter called casts. The casts form a high-quality natural fertilizer. In addition, earthworms mix of soil both vertically and horizontally, improving aeration and drainage.
Insects such as ants and termites also can be exceedingly numerous under favorable climatic and soil conditions. In addition, mammals such as moles, field mice, gophers, and prairie dogs sometimes are present in sufficient numbers to have significant impact on the soil. These animals primarily work the soil mechanically. As a result, the soil is aerated broken up, fertilized, and brought to the surface, hastening soil development. "
R36P2
"Early Ideas About Deep-sea BiologyIn 1841 Edward Forbes was offered the chance to serve as naturalist aboard HMS Beacon, an English Royal Navy ship assigned to survey the Aegean Sea. For a year and a half the Beacon crisscrossed the Aegean waters. During that time Forbes was able to drag this small, triangular dregdge - a tool with a leather net for capturing creatures along the sea bottom - at a hundred locations, at depths ranging from 6 to 1380 feet. He collected hundreds of different species of animals, and he saw that they were distributed in eight different depth zones, each containing its own distinct assemblage of animal life, the way zones of elevation on the side of a mountain are populated by distinct sets of plants.
Forbes also thought he saw, as he later told the British Association, that ""the number of species and individuals diminishes as we descend, pointing to a zero in the distribution of animal life as yet unvisited."" This zero, Forbes casually speculated-he simply extended a line on his graph of animal number versus depth-probably began at a depth of 1,800 feet. Below that was the final zone in Forbes's scheme, zone nine, a zone that covered most of the ocean floor and thus most of the solid surface of Earth: Forbes called this the azoic zone, where no animal, to say nothing of plants, could survive.
Forbes's azoic zone was entirely plausible at the time, and it was certainly far from the strangest idea that was then entertained about the deep sea. In the first decade of the nineteenth century, a French naturalist named Francois Peron had sailed around the world measuring the temperature of the ocean. He found that the deeper the water, the colder it got, and he concluded that the seafloor was covered with a thick layer of ice. Peron ignored the fact that water expands when it freezes and that ice therefore floats. A more popular belief at the time was that water at great depth would be compressed to such a density that nothing could sink through it. This ignored the fact that water is all but incompressible. But even the more sensible naturalists of the day were guilty of a similar misconception. They imagined the deep sea as being filled with an unmoving and undisturbable pool of cold, dense water. In reality the deep is always being refreshed by cold water sinking from above.
The central implication of all these misconceptions was that nothing could live in the abyss (deep), just as Forbes's observations seemed to indicate. But Forbes erred in two ways. One was the particular study site he happened to use as a springboard for his sweeping postulate of a lifeless abyss. Although the Aegean had been the birthplace of marine biology, its depths are now known to be exceptionally lacking in animal diversity. Moreover, through no fault of his own, Forbes was not particularly successful at sampling such life as did exist at the bottom of the Aegean. It was his dredge that was inadequate. Its opening was so small and the holes in the net so large that the dredge inevitably missed animals. Many of those it did catch must have poured out of its open mouth when Forbes reeled it in. His azoic zone, then, was a plausible but wild extrapolation from pioneering but feeble data.
As it turned out, the existence of the azoic zone had been disproved even before Forbes suggested it, and the theory continued to be contradicted regularly throughout its long and influential life. Searching for the Northwest Passage from the Atlantic to the Pacific in 1818, Sir John Ross had lowered his ""deep-sea clam""-a sort of bivalved sediment scoop-into the water of Baffin Bay ( an inlet between the Atlantic and Arctic oceans), which the determined to be more than a thousand fathoms deep in some places. Modern soundings indicate he overestimated his depths by several hundred fathoms, but in any case Ross's clam dove several times deeper than Forbes's dredge. It brought back mud laced with worms, and starfish that dad entangled themselves in the line at depths well below the supposed boundary of the azoic zone. "
R36P3
"Industrial Melanism: The Case of the Peppered MothThe idea of natural selection is that organisms in a species that have characteristics favoring survival are most likely to survive and produce offspring with the same characteristics. Because the survival of organisms with particular characteristics is favored over the survival of other organisms in the same species that lack these characteristics, future generations of the species are likely to include more organisms with the favorable characteristics.
One of the most thoroughly analyzed examples of natural selection in operation is the change in color that has occurred in certain populations of the peppered moth, Biston betularia, in industrial regions of Europe during the past 100 years. Originally moths were uniformly pale gray or whitish in color; dark-colored (melanic) individuals were rare and made up less than 2 percent of the population. Over a period of decades, dark-colored forms became an increasingly large fraction of some populations and eventually came to dominate peppered moth populations in certain areas -especially those of extreme industrialization such as the Ruhr Valley of Germany and the Midlands of England. Coal from industry released large amounts of black soot into the environment, but the increase of the dark-colored forms was not due to genetic mutations caused by industrial pollution. For example, caterpillars that feed on soot-covered leaves did not give rise to dark- colored adults. Rather, pollution promoted the survival of dark forms on soot-covered trees. Melanics were normally quickly eliminated in nonindustrial areas by adverse selection; birds spotted them easily. This phenomenon, an increase in the frequency of dark-colored mutants in polluted areas, is known as industrial melanism. The North American equivalent of this story is another moth, the swettaria form of Biston cognataria, first noticed in industrialized areas such as Chicago and New York City in the early 1900s. By 1961 it constituted over 90 percent of the population in parts of Michigan.
The idea that natural selection was responsible for the changing ratio of dark- to light-colored peppered moths was developed in the 1950s by H. B. D. Kettlewell of Oxford University. If natural selection was the explanation, then there should be different survival rates for dark- and light- colored moths. To determine whether this was true, Kettlewell released thousands of light and dark moths (each marked with a paint spot) into rural and industrialized areas. In the nonindustrial area of Dorset, he recaptured 14.6 percent of the pale forms but only 4.7 percent of the dark forms. In the industrial area of Birmingham, the situation was reversed: 13 percent of pale forms but 27.5 percent of dark forms were recaptured.
Clearly some environmental factor was responsible for the greater survival rates of dark moths. Birds were predators of peppered moths. Kettlewell hypothesized that the normal pale forms are difficult to see when resting on lichen-covered trees, whereas dark forms are conspicuous. In industrialized areas, lichens are destroyed by pollution, tree barks become darker, and dark moths are the ones birds have difficulty detecting. As a test, Kettlewell set up hidden observation positions and watched birds voraciously eat moths placed |on tree trunks of a contrasting color. The action of natural selection in producing a small but highly significant step of evolution was seemingly demonstrated, with birds as the selecting force.
Not every researcher has been convinced that natural selection by birds is the only explanation of the observed frequencies of dark and light peppered moths. More recent data, however, provide additional support for Kettleweir's ideas about natural selection. The light-colored form of the peppered moth is making a strong comeback. In Britain, a Clean Air Act was passed in 1965. Sir Cyril Clarke has been trapping moths at his home in Liverpool, Merseyside, since 1959. Before about 1975, 90 percent of the moths were dark, but since then there has been a steep decline in melanic forms, and in 1989 only 29.6 percent of the moths caught were melanic. The mean concentration of sulphur dioxide pollution fell from about 300 micrograms per cubic meter in 1970 to less than 50 micrograms per cubic meter in 1975 and has remained fairly constant since then. If the spread of the light-colored form of the moth continues at the same speed as the melanic form spread .in the last century, soon the melanic form will again be only an occasional resident of the Liverpool area. "
R37P1
"Thales And The MilesiansWhile many other observers and thinkers had laid the groundwork for science, Thales (circa 624 B.C.E-ca 547 B.C.E.), the best known of the earliest Greek philosophers, made the first steps toward a new, more objective approach to finding out about the world. He posed a very basic question: ""What is the world made of? "" Many others had asked the same question before him, but Thales based his answer strictly on what he had observed and what he could reason out-not on imaginative stories about the gods or the supernatural. He proposed water as the single substance from which everything in the world was made and developed a model of the universe with Earth as a flat disk floating in water.
Like most of the great Greek philosophers, Thales had an influence on others around him. His two best-known followers, though there were undoubtedly others who attained less renown, were Anaximander and Anaximenes. Both were also from Miletus (located on the southern coast of present-day Turkey) and so, like Thales, were members of the Milesian School. Much more is known about Anaximander than about Anaximenes, probably because Anaximander, who was born sometime around 610 B.C.E, ambitiously attempted to write a comprehensive history of the universe. As would later happen between another teacher-student pair of philosophers, Plato and Aristotle, Anaximander disagreed with his teacher despite his respect for him. He doubted that the world and all its contents could be made of water and proposed instead a formless and unobservable substance he called ""apeiron"" that was the source of all matter.
Anaximander's most important contributions, though, were in other areas. Although he did not accept that water was the prime element, he did believe that all life originated in the sea, and he was thus one of the first to conceive of this important idea. Anaximander is credited with drawing up the first world map of the Greeks and also with recognizing that Earth's surface was curved. He believed, though, that the shape of Earth was that of a cylinder rather than the sphere that later Greek philosophers would conjecture. Anaximander, observing the motions of the heavens around the polestar, was probably the first of the Greek philosophers to picture the sky as sphere completely surrounding Earth-an idea that, elaborated upon later, would prevail until the advent of the Scientific Revolution in the seventeenth century.
Unfortunately, most of Anaximander's written history of the universe was lost, and only a few fragments survive today. Little is known about his other ideas. Unfortunately, too, most of the written work for Anaximenes, who may have been Anaximander's pupil, has also been lost. All we can say for certain about Anaximenes, who was probably born around 560 BCE, is that following in the tradition of Anaximander, he also disagreed with his mentor. The world, according to Anaximenes, was not composed of either water or apeiron, but air itself was the fundamental element of the universe. Compressed, it became water and earth, and when rarefied or thinned out, it heated up to become fire. Anaximenes may have also been the first to study rainbows and speculate upon their natural rather than supernatural cause.
With the door opened by Thales and the other early philosophers of Milestus, Greek thinkers began to speculate about the nature of the universe. This exciting burst of intellectual activity was for the most part purely creative. The Greeks, from Thales to Plato and Aristotle, were philosophers and not scientists in today's sense. It is possible for anyone to create ""ideas"" about the nature and structure of the universe, for instance, and many times these ideas can be so consistent and elaborately structured, or just so apparently obvious, that they can be persuasive to many people. A scientific theory about the universe, however, demands much more than the various observations and analogies that were woven together to form systems of reasoning, carefully constructed as they were, that would eventually culminate in Aristotle's model of the world and the universe. Without experimentation and objective, critical testing of their theories, the best these thinkers could hope to achieve was some internally consistent speculation that covered all the bases and satisfied the demands of reason. "
R37P2
"Direct Species TranslocationIt is becoming increasingly common for conservationists to move individual animals or entire species from one site to another. This may be either to establish a new population where a population of conspecifics (animals or plants belonging to the same species) has become extinct or to add individuals to an existing population. The former is termed reintroduction and the latter reinforcement. In both cases, wild individuals are captured in one location and translocated directly to another.
Direct translocation has been used in a wide range of plants and animals and was carried out to maintain populations as a source of food long before conservation was a familiar term. The number of translocations carried out under the banner of conservation has increased rapidly, and this has led to criticism of the technique because of the lack of evaluation of its efficacy and because of its potential disadvantages. The nature of translocation ranges from highly organized and researched national or international programs to ad hoc releases of rescued animals by well-intentioned animal lovers. In a fragmented landscape where many populations and habitats are isolated from others, translocations can play an effective role in conservation strategies; they can increase the number of existing populations or increase the size, genetic diversity, and demographic balance of a small population, consequently increasing its chances of survival.
Translocation clearly has a role in the recovery of species that have substantially declined and is the most likely method by which many sedentary species can recover all or part of their former range. However, against this is the potential for reinforcement translocations to spread disease from one population to another or to introduce deleterious or maladaptive genes to a population. Additionally, translocation of predators or competitors may have negative impacts on other species, resulting in an overall loss of diversity. Last but not least of these considerations is the effort and resources required in this type of action, which need to be justified by evidence of the likely benefits.
Despite the large number of translocations that have taken place, there is surprisingly little evidence of the efficacy of such actions. This is partly because many translocations have not been strictly for conservation; neither have they been official nor legal, let alone scientific in their approach. Successful translocations inevitably get recorded and gain attention, whereas failures may never be recorded at all. This makes appraisal of the method very difficult. One key problem is a definition of success. Is translocation successful if the individuals survive the first week or a year, or do they need to reproduce for one or several generations？ Whatever the answer, it is clear that a general framework is required to ensure that any translocation is justified, has a realistic chance of success, and will be properly monitored and evaluated for the benefit of future efforts.
An example of apparent translocation success involves the threatened Seychelles warbler. This species was once confined to Cousin Island, one of the Seychelles islands, and reduced to 26 individuals. Careful habitat management increased this number to over 300 birds, but the single population remained vulnerable to local catastrophic events. The decision was taken to translocate individuals to two nearby islands to reduce this risk. The translocations took place in 1988 and 1990, and both have resulted in healthy breeding populations. A successful translocation exercise also appears to have been achieved with red howler monkeys in French Guiana. A howler population was translocated from a site due to be flooded for hydroelectric power generation. The release site was an area where local hunting had reduced the density of the resident howler population. Released troops of monkeys were kept under visual observation and followed by radio tracking of 16 females. Although the troops appeared to undergo initial problems, causing them to split up, all the tracked females settled into normal behavioral patterns.
Unfortunately, the success stories are at least matched by accounts of failure. Reviewing translocation of amphibians and reptiles, researchers C.Kenneth Dodd and Richard A. Siegel concluded that most projects have not demonstrated success as conservation techniques and should not be advocated as though they were acceptable management and mitigation practices. "
R37P3
"Modern Architecture in the United StatesAt the end of the nineteenth century, there were basically two kinds of buildings in the United States. On one hand were the buildings produced for the wealthy or for civic purposes, which tended to echo the architecture of the past and to use traditional styles of ornamentation. On the other hand were purely utilitarian structures, such as factories and grain elevators, which employed modern materials such as steel girders and plate glass in an undisguised and unadorned manner. Such buildings, however, were viewed in a category separate from ""fine"" architecture, and in fact were often designed by engineers and builders rather than architects. The development of modern architecture might in large part be seen as an adaptation of this sort of functional building and its pervasive application for daily use. Indeed, in this influential book Toward a New Architecture, the Swiss architect Le Corbusier illustrated his text with photographs of American factories and grain storage silos, as well as ships, airplanes, and other industrial objects. Nonetheless, modern architects did not simply employ these new materials in a strictly practical fashion--they consciously exploited their aesthetic possibilities. For example, glass could be used to open up walls and eliminate their stone and brick masonry because large spaces could now be spanned with steel beams.
The fundamental premise of modern architecture was that the appearance of the building should exhibit the nature of its materials and forms of physical support. This often led to effects that looked odd from a traditional standpoint but that became hallmarks of modern architecture for precisely this reason. For example, in traditional architecture, stone or brick walls served a structural role, but in a steel-beam building the walls were essentially hung from the internal skeleton of steel beams, which meant that walls and corners no longer needed to be solid but could be opened up in unexpected ways. At the Fagus shoe factory in Germany, for example, German architect Walter Gropius placed glass walls in the corners, effectively breaking open the box of traditional architecture and creating a new sense of light and openness. Similarly, steel beams could be used to construct balconies that projected out from the building without any support beneath them. These dramatic balconies quickly became a signature of modern architects such as Frank Lloyd Wright. Wright's most dramatic residence, Fallingwater, has balconies that thrust far out over a stream in a way that seems to defy gravity.
The ways in which new technology transformed architectural design are dramatically illustrated through the evolution of the high-rise office building. After ten or twelve stories, masonry construction reaches a maximum possible height, since it runs into difficulties of compression and of inadequate lateral strength to combat wind shear. Steel construction, on the other hand, can support a building of 50 or 100 stories without difficulty. Such buildings were so different from any previous form of architecture that they quickly acquired a new name--the skyscraper.
From the standpoint of real estate developers, the purpose of skyscrapers was to increase rental space in valuable urban locations. But to create usable high-rise buildings, a number of technical challenges needed to be solved. One problem was getting people to the upper floors, since after five or six stories it becomes exhausting to climb stairs. Updated and electrified versions of the freight elevator that had been introduced by Elisha Graves Otis in 1853 (several decades before skyscraper construction) solved this problem. Another issue was fire safety. The metal supporting buildings became soft when exposed to fire and collapsed relatively quickly. (They could melt at 2700 Fahrenheit, whereas major fires achieve temperatures of 3000degrees). However, when the metal is encased in fire-retardant materials, its vulnerability to fire is much decreased. In Chicago, a system was developed for surrounding the metal components with hollow tiles made from brick-like terra-cotta. Such tiles are impervious to fire. The terra-cotta tiles were used both to encase the supporting members and as flooring. A structure built with steel beams protected by terra-cotta tiles was still three times lighter than a comparably sized building that used masonry construction, so the weight of the tiles was not a problem. "
R38P1
"MicroscopesBefore microscopes were first used in the seventeenth century, no one knew that living organisms were composed of cells. The first microscopes were light microscopes, which work by passing visible light through a specimen. Glass lenses in the microscope bend the light to magnify the image of the specimen and project the image into the viewer's eye or onto photographic film. Light microscopes can magnify objects up to 1,000 times without causing blurriness.
Magnification, the increase in the apparent size of an object, is one important factor in microscopy. Also important is resolving power, a measure of the clarity of an image. Resolving power is the ability of an optical instrument to show two objects as separate. For example, what looks to the unaided eye like a single star in the sky may be resolved as two stars with the help of a telescope. Any optical device is limited by its resolving power. The light microscope cannot resolve detail finer than 0.2 micrometers, about the size of the smallest bacterium; consequently, no matter how many times its image of such a bacterium is magnified, the light microscope cannot show the details of the cell's internal structure.
From the year 1665, when English microscopist Robert Hooke discovered cells, until the middle of the twentieth century, biologists had only light microscopes for viewing cells. But they discovered a great deal, including the cells composing animal and plant tissues, microscopic organisms, and some of the structures within cells. By the mid-1800s, these discoveries led to the cell theory, which states that all living things are composed of cells and that all cells come from other cells.
Our knowledge of cell structure took a giant leap forward as biologists began using the electron microscope in the 1950s. Instead of light, the electron microscope uses a beam of electrons and has a much higher resolving power than the light microscope. In fact, the most powerful modern electron microscopes can distinguish objects as small as 0.2 nanometers, a thousandfold improvement over the light microscope. The period at the end of this sentence is about a million times bigger than an object 0.2 nanometers in diameter, which is the size of a large atom. Only under special conditions can electron microscopes detect individual atoms. However, cells, cellular organelles, and even molecules like DNA and protein are much larger than single atoms.
Biologists use the scanning electron microscope to study the detailed architecture of cell surfaces. It uses an electron beam to scan the surface of a cell or group of cells that have been coated with metal. The metal stops the beam from going through the cells. When the metal is hit by the beam, it emits electrons. The electrons are focused to form an image of the outside of the cells. The scanning electron microscope produces images that look three-dimensional.
The transmission electron microscope, on the other hands, is used to study the details of internal cell structure. Specimens are cut into extremely thin sections, and the transmission electron microscope aims an electron beam through a section, just as a light microscope aims a beam of light through a specimen. However, instead of lenses made of glass, the transmission electron microscope uses electromagnets as lenses, as do all electron microscopes. The electromagnets bend the electron beam to magnify and focus an image onto a viewing screen or photographic film.
Electron microscopes have truly revolutionized the study of cells and cell organelles. Nonetheless, they have not replaced the light microscope. One problem with electron microscopes is that they cannot be used to study living specimens because the specimen must be held in a vacuum chamber; that is, all the air and liquid must be removed. For a biologist studying a living process, such as the whirling movement of a bacterium, a light microscope equipped with a video camera might be better than either a scanning electron microscope or a transmission electron microscope. Thus, the light microscope remains a useful tool, especially for studying living cells. The size of a cell often determines the type of microscope a biologist uses to study it. "
R38P2
"The Raccoons's SuccessRaccoons have a vast transcontinental distribution, occurring throughout most of North America and Central America. They are found from southern Canada all the way to Panama, as well as on islands near coastal areas. They occur in each of the 49 states of the continental United States. Although raccoons are native only to the Western Hemisphere, they have been successfully transplanted to other parts of the globe.
Following a decline to a relatively low population level in the 1930s, raccoons began to prosper following their 1943 breeding season. A rapid population surge continued throughout the 1940s, and high numbers have been sustained ever since. By the late 1980s, the number of raccoons in North America was estimated to be at least 15 to 20 times the number that existed during the 1930s. By now, their numbers have undoubtedly grown even more, as they have continued to expand into new habitats where they were once either rare or absent, such as sandy prairies, deserts, coastal marshes, and mountains. Their spread throughout the Rocky Mountain West is indicative of the fast pace at which they can exploit new environments. Despite significant numbers being harvested and having suffered occasional declines, typically because of disease, the raccoon has consistently maintained high population levels.
Several factors explain the raccoon's dramatic increase in abundance and distribution. First, their success has been partially attributed to the growth of cities, as they often thrive in suburban and even urban settings. Furthermore, they have been deliberately introduced throughout the continent. Within the United States, they are commonly taken from one area to another, both legally and illegally, to restock hunting areas and, presumably, because people simply want them to be part of their local fauna. Their appearance and subsequent flourishing in Utah's Great Salt Lake valley within the last 40 years appears to be from such an introduction. As an example of the ease with which transplanted individuals can succeed, raccoons from Indiana (midwestern United States) have reportedly been able to flourish on islands off the coast of Alaska.
The raccoon's expansion in various areas may also be due to the spread of agriculture. Raccoons have been able to exploit crops, especially corn but also cereal grains, which have become dependable food sources for them. The expansion of agriculture, however, does not necessarily lead to rapid increases in their abundance. Farming in Kansas and eastern Colorado (central and western United States) proceeded rapidly in the 1870s and 1880s, but this was about 50 years before raccoons started to spread out from their major habitat, the wooded river bottomlands. They have also expanded into many areas lacking any agriculture other than grazing and into places without forests or permanent streams.
Prior to Europeans settling and farming the Great Plains Region, raccoons probably were just found along its rivers and streams and in the wooded areas of its southeastern section. With the possible exception of the southern part of the province of Manitoba, their absence was notable throughout Canada. They first became more widely distributed in the southern part of Manitoba, and by the 1940s were abundant throughout its southeastern portion. In the 1950s their population swelled in Canada. The control of coyotes in the prairie region in the 1950s may have been a factor in raccoon expansion. If their numbers are sufficient coyotes might be able to suppress raccoon populations (though little direct evidence supports this notion). By the 1960s the raccoon had become a major predator of the canvasback ducks nesting in southwestern Manitoba.
The extermination of the wolf from most of the contiguous United States may have been a critical factor in the raccoon's expansion and numerical increase. In the eighteenth century, when the wolfs range included almost all of North America, raccoons apparently were abundant only in the deciduous forests of the East, Gulf Coast, and Great Lakes regions, though they also extended into the wooded bottomlands of the Midwest's major rivers. In such areas, their arboreal habits and the presence of hollow den trees should have offered some protection from wolves and other large predators. Even though raccoons may not have been a significant part of their diet, wolves surely would have tried to prey on those exposed in relatively treeless areas. "
R38P3
"Transgenic PlantsGenes from virtually any organism, from viruses to humans, can now be inserted into plants, creating what are known as transgenic plants. Now used in agriculture, there are approximately 109 million acres of transgenic crops grown worldwide, 68 percent of which are in the United States. The most common transgenic crops are soybeans, corn, cotton, and canola. Most often, these plants either contain a gene making them resistant to the herbicide glyphosate or they contain an insect-resistant gene that produces a protein called Bt toxin.
On the positive side, proponents of transgenic crops argue that these crops are environmentally friendly because they allow farmers to use fewer and less noxious chemicals for crop production. For example, a 21 percent reduction in the use of insecticide has been reported on Bt cotton (transgenic cotton that produces Bt toxin). In addition, when glyphosate is used to control weeds, other more persistent herbicides do not need to be applied.
On the negative side, opponents of transgenic crops suggest that there are many questions that need to be answered before transgenic crops are grown on a large scale. One question deals with the effects that Bt plants have on nontarget organisms such as beneficial insects, worms, and birds that consume the genetically engineered crop. For example, monarch caterpillars feeding on milkweed plants near Bt cornfields will eat some corn pollen that has fallen on the milkweed leaves. Laboratory studies indicate that caterpillars can die from eating Bt pollen. However, field tests indicate that Bt corn is not likely to harm monarchs. Furthermore, the application of pesticides (the alternative to growing Bt plants) has been demonstrated to cause widespread harm to nontarget insects.
Another unanswered question is whether herbicide-resistant genes will move into the populations of weeds. Crop plants are sometimes grown in areas where weedy relatives also live. If the crop plants hybridize and reproduce with weedy relatives, then this herbicide-resistant gene will be perpetuated in the offspring. In this way, the resistant gene can make its way into the weed population. If this happens, a farmer can no longer use glyphosate, for example, to kill those weeds. This scenario is not likely to occur in many instances because there are no weedy relatives growing near the crop plant. However, in some cases, it may become a serious problem. For example, canola readily hybridizes with mustard weed species and could transfer its herbicide-resistant genes to those weeds.
We know that evolution will occur when transgenic plants grown on a large scale over a period of time. Of special concern is the development of insect populations resistant to the Bt toxin. This pesticide has been applied to plants for decades without the development of insect-resistant populations. However, transgenic Bt plants express the toxin in all tissues throughout growing season. Therefore, all insects carrying genes that make them susceptible to the toxin will die. That leaves only the genetically resistant insects alive to perpetuate the population. When these resistant insects mate, they will produce a high proportion of offspring capable of surviving in the presence of the Bt toxin. Farmers are attempting to slow the development of insect resistance in Bt crops by, for example, planting nontransgenic border rows to provide a refuge for susceptible insects. These insects may allow Bt susceptibility to remain in the population.
Perhaps the most serious concern about the transgenic crop plants currently in use is that they encourage farmers to move farther away from sustainable agricultural farming practices, meaning ones that allow natural resources to continually regenerate over the long run. Transgenics, at least superficially, simplify farming by reducing the choices made by the manager. Planting a glyphosate-resistant crop commits a farmer to using that herbicide for the reason, probably to the exclusion of all other herbicides and other weed-control practices. Farmers who use Bt transgenics may not feel that they need to follow through with integrated pest-management practices that use beneficial insects and timely applications of pesticides to control insect pests. A more sustainable approach would be to plant nontransgenic corn, monitor the fields throughout the growing season, and then apply a pesticide only if and when needed. "
R39P1
"Early Writing SystemsScholars agree that writing originated somewhere in the Middle East, probably Mesopotamia, around the fourth millennium B.C.E. It is from the great libraries and word-hoards of these ancient lands that the first texts emerged. They were written on damp clay tablets with a wedged (or V-shaped) stick; since the Latin word for wedge is cunea, the texts are called cuneiform. The clay tablets usually were not fired; sun drying was probably reckoned enough to preserve the text for as long as it was being used. Fortunately, however, many tablets survived because they were accidentally fired when the buildings they were stored in burned.
Cuneiform writing lasted for some 3,000 years, in a vast line of succession that ran through Sumer, Akkad, Assyria, Nineveh, and Babylon, and preserved for us fifteen languages in an area represented by modern-day Iraq, Syria, and western Iran. The oldest cuneiform texts recorded the transactions of tax collectors and merchants, the receipts and bills of sale of an urban society. They had to do with things like grain, goats, and real estate. Later, Babylonian scribes recorded the laws and kept other kinds of records. Knowledge conferred power. As a result, the scribes were assigned their own goddess, Nisaba, later replaced by the god Nabu of Borsippa, whose symbol is neither weapon nor dragon but something far more fearsome, the cuneiform stick.
Cuneiform texts on science, astronomy, medicine, and mathematics abound, some offering astoundingly precise data. One tablet records the speed of the Moon over 248 days; another documents an early sighting of Halley's Comet, from September 22 to September 28, 164 B.C.E. More esoteric texts attempt to explain old Babylonian customs, such as the procedure for curing someone who is ill, which included rubbing tar and gypsum on the sick person's door and drawing a design at the foot of the person's bed. What is clear from the vast body of texts (some 20,000 tablets were found in King Ashurbanipal's library at Nineveh) is that scribes took pride in their writing and knowledge.
The foremost cuneiform text, the Babylonian Epic of Gilgamesh, deals with humankind's attempts to conquer time. In it, Gilgamesh, king and warrior, is crushed by the death of his best friend and so sets out on adventures that prefigure mythical heroes of ancient Greek legends such as Hercules. His goal is not just to survive his ordeals but to make sense of this life. Remarkably, versions of Gilgamesh span 1,500 years, between 2100 B.C.E and 600 B.C.E., making the story the epic of an entire civilization.
The ancient Egyptians invented a different way of writing and a new substance to write on --papyrus, a precursor of paper, made from a wetland plant. The Greeks had a special name for this writing: hiero glyphic, literally ""sacred writing."" This, they thought, was language fit for the gods, which explains why it was carved on walls of pyramids and other religious structures. Perhaps hieroglyphics are Egypt's great contribution to the history of writing: hieroglyphic writing, in use from 3100 B.C.E. until 394 B.C.E., resulted in the creation of texts that were fine art as well as communication. Egypt gave us the tradition of the scribe not just as educated person but as artist and calligrapher.
Scholars have detected some 6,000 separate hieroglyphic characters in use over the history of Egyptian writing, but it appears that never more than a thousand were in use during any one period. It still seems a lot to recall, but what was lost in efficiency was more than made up for in the beauty and richness of the texts. Writing was meant to impress the eye with the vastness of creating itself. Each symbol or glyph--the flowering reed (pronounced like ""i""), the owl (""m""), the quail chick (""w""), etcetera--was a tiny work of art. Manuscripts were compiled with an eye to the overall design. Egyptologists have noticed that the glyphs that constitute individual words were sometimes shuffled to make the text more pleasing to the eye with little regard for sound or sense. "
R39P2
"The Extinction of MoaBetween 80 and 85 million years ago, Gondwanaland, a giant continent made up of what today is Africa, Antarctica, Australia, and South America, broke up, thus causing what is now New Zealand to become separated from the larger landmass. After the separation, any creature unable to cross a considerable distance of ocean could not migrate to New Zealand. Snakes and most mammals evolved after the separation. Thus there are no New Zealand snakes, and bats, which flew there, and seals, which swam there, were the only mammals on New Zealand when Polynesian settlers (the Maori) arrived there about a thousand years ago.
When the Maori arrived in New Zealand, they encountered birds that had been evolving for 80 million years without the presence of mammalian predators. The most striking of these animals must have been moa. Now extinct, moa were gigantic wingless birds that stood as much as 10 feet (3 meters) tall and weighed as much as 550 pounds (250 kilograms). They are known from a diverse array of remains including eggshells, eggs, a few mummified carcasses, vast numbers of bones, and some older fossilized bones. The species of moa that are currently recognized occupied ecological niches customarily filled elsewhere by large mammalian browsing herbivores. They may have had relatively low reproductive rates; apparently, they usually laid only one egg at a time.
It seems possible that when Captain James Cook first visited New Zealand in 1769, moa (or at least one of the moa species) may have still survived in the remote areas in the western part of New Zealand's South Island. If so, these individuals would have been the last of their kind. Climatic conditions in New Zealand appear to have been relatively stable over the period during which moa became extinct. Different factors could have worked in concert to account for their abrupt disappearance.
Vegetation was considerably altered by the Maori occupation of New Zealand, a change not easily explained by climate variation or other possible factors. Forest and shrubland burning appears to have reduced the prime habitat of many moa species. However, the main forest burning started around 700 years ago, after what current archaeological evidence indicates was the most intensive stage of moa hunting. While there appears to have been extensive burning on the east side of New Zealand's South Island, large forest tracts remained in the most southern part of the island. Because major habitat destruction seems to have occurred after moa populations already were depleted, and because some habitat that could have sheltered moa populations remained, it would seem that other factors were also at work in the extinction of these birds.
For South Island, human predation appears to have been a significant factor in the depletion of the population of moa. At one excavated Maori site, moa remains filled six railway cars. The density of Maori settlements and artifacts increased substantially at the time of the most intensive moa hunting (900 to 600 years ago). This period was followed by a time of decline in the Maori population and a societal transition to smaller, less numerous settlements. The apparent decline fits the pattern expected as a consequence of the Maori's overexploitation of moa.
Finally, the Maori introduced the Polynesian rat and the dog to New Zealand. The actions of these potential nest predators could have reduced moa populations without leaving much direct evidence. The Maori may have also inadvertently brought pests and disease organisms in fowls, which could have crossed over to eradicate moa populations. The possibility of analyzing ancient DNA to identify past diseases of extinct animals is being explored. However, evidence of such diseases is difficult to determine directly from paleoecological or archaeological remains. For these reasons, it is hard to determine the likelihood that introduced disease organisms were a cause of the decline of moa, but they are potentially significant.
While the last of these possible causes remains speculative, definite clues exist for the action of the first two causes. The story of moa species and their demise raises ecological issues on the vulnerability of species to human-caused changes--including altered vegetative cover of the landscape, change in the physical environment, and modification of the flora and fauna of a region by eliminating some species and introducing others. "
R39P3
"Forest Fire SuppressionForest fires have recently increased in intensity and extent in some forest types throughout the western United States. This recent increase in fires has resulted partly from climate change (the recent trend toward hot, dry summers) and partly from human activities, for complicated reasons that foresters came increasingly to understand about 30 years ago but whose relative importance is still debated. One factor is the direct effect of logging, which often turns a forest into something approximating a huge pile of kindling (wood for burning): the ground in a logged forest may remain covered with branches and treetops, left behind when the valuable trunks are carted away; a dense growth of new vegetation springs up, further increasing the forest's fuel loads; and the trees logged and removed are of course the biggest and most fire-resistant individuals, leaving behind smaller and more flammable trees.
Another factor is that the United States Forest Service in the first decade of the 1900s adopted the policy of fire suppression (attempting to put out forest fires) for the obvious reason that it did not want valuable timber to go up in smoke, or people's homes and lives to be threatened. The Forest Service's announced goal became ""Put out every forest fire by 10:00 A.M on the morning after the day when it is first reported."" Firefighters became much more successful at achieving that goal after 1945, thanks to improved firefighting technology. For a few decades the amount of land burnt annually decreased by 80 percent. That happy situation began to change in the 1980s, due to the increasing frequency of large forest fires that were essentially impossible to extinguish unless rain and low winds combined to help. People began to realize that the United States federal government's fire-suppression policy was contributing to those big fires and that natural fires caused by lighting had previously played an important role in maintaining forest structure.
The natural role of fire varies with altitude, tree species, and forest type. To make Montana's low-altitude ponderosa pine forest as an example, historical records, plus counts of annual tree rings and datable fire scars on tree stumps, demonstrated that a ponderosa pine forest experiences a lightning-lit fire about once a decade under natural conditions (i.e.., before fire suppression began around 1910 and became effective after 1945). The mature ponderosa trees have bark two inches thick and are relatively resistant to fire, which instead burns out the understory-the lower layer-of fire-sensitive Douglas fir seedlings that have grown up since the previous fire. But after only a decade's growth until the next fire, those young seedling plants are still too low for fire to spread from them into the crowns of the ponderosa pine trees. Hence the fire remains confined to ground and understory. As a result, many natural ponderosa pine forests have a parklike appearance, with low fuel loads, big trees spaced apart, and a relatively clear understory.
However, loggers concentrated on removing those big, old, valuable, fire-resistant ponderosa pines, while fire suppression for decades let the understory fill up with Douglas fir saplings that would in turn become valuable when full-grown. Tree densities increased from 30 to 200 trees per acre, the forest's fuel load increased by a factor of 6, and the government repeatedly failed to appropriate money to thin out the saplings. When a fire finally does start in a sapling-choked forest, whether due to lightning or human carelessness or (regrettably often) intentional arson, the dense, tall saplings young trees may become a ladder that allows the fire to jump into the crowns of the trees. The outcome is sometimes an unstoppable inferno.
Foresters now identify the biggest problem in managing Western forests as what to do with those increased fuel loads that built up during the previous half century of effective fire suppression. In the wetter eastern United States, dead trees rot away more quickly than in the drier West, where more dead trees persist like giant matchsticks. In an ideal world, the Forest Service would manage and restore the forests, thin them out, and remove the dense understory by cutting or by controlled small fires. But no politician or voter wants to spend what it would cost to do that. "
R40P1
Ancient AthensOne of the most important changes in Greece during the period from 800 B.C. to 500 B.C. was the rise of the polis, or city-state, and each polis developed a system of government that was appropriate to its circumstances. The problems that were faced and solved in Athens were the sharing of political power between the established aristocracy and the emerging other classes, and the adjustment of aristocratic ways of life to the ways of life of the new polis. It was the harmonious blending of all of these elements that was to produce the classical culture of Athens.
Entering the polis age, Athens had the traditional institutions of other Greek protodemocratic states: an assembly of adult males, an aristocratic council, and annually elected officials. Within this traditional framework the Athenians, between 600 B.C. and 450 B.C., evolved what Greeks regarded as a fully-fledged democratic constitution, though the right to vote was given to fewer groups of people than is seen in modem times.
The first steps toward change were taken by Solon in 594 B.C., when he broke the aristocracy's stranglehold on elected offices by establishing wealth rather than birth as the basis of office holding, abolishing the economic obligations of ordinary Athenians to the aristocracy, and allowing the assembly (of which all citizens were equal members) to overrule the decisions of local courts in certain cases. The strength of the Athenian aristocracy was further weakened during the rest of the century by the rise of a type of government known as a tyranny which is a form of interim rule by a popular strongman (not rule by a ruthless dictator as the modem use of the term suggests to us). The Peisistratids, as the succession of tyrants were called (after the founder of the dynasty, Peisistratos), strengthened Athenian central administration at the expense of the aristocracy by appointing judges throughout the region, producing Athens' first national coinage, and adding and embellishing festivals that tended to focus attention on Athens rather than on local villages of the surrounding region. By the end of the century, the time was ripe for more change: the tyrants were driven out, and in 508 B.C. a new reformer, Cleisthenes, gave final form to the developers reducing aristocratic control already under way.
Cleisthenes' principal contribution to the creation of democracy at Athens was to complete the long process of weakening family and clan structures, especially among the aristocrats, and to set in their place locality-based corporations called demes, which became the point of entry for all civic and most religious life in Athens. Out of the demes were created 10 artificial tribes of roughly equal population. From the demes, by either election or selection, came 500 members of a new council, 6,000 jurors for the courts, 10 generals, and hundreds of commissioners. The assembly was sovereign in all matters but in practice delegated its power to subordinate bodies such as the council, which prepared the agenda for meetings of the assembly, and the courts, which took care of most judicial matters. Various committees acted as an executive branch, implementing policies of the assembly and supervising, for instance, the food and water supplies and public buildings. This wide-scale participation by the citizenry in the government distinguished the democratic form of the Athenian polis from other, less liberal forms.
The effect of Cleisthenes' reforms was to establish the superiority of the Athenian community as a whole over local institutions without destroying them. National politics rather than local or deme politics became the focal point. At the same time, entry into national politics began at the deme level and gave local loyalty a new focus: Athens itself. Over the next two centuries the implications of Cleisthenes reforms were fully exploited.
During the fifth century B.C. the council of 500 was extremely influential in shaping policy. In the next century, however, it was the mature assembly that took on decision-making responsibility. By any measure other than that of the aristocrats，who had been upstaged by the supposedly inferior "people," the Athenian democracy was a stunning success. Never before, or since, have so many people been involved in the serious business of self-govemance. It was precisely this opportunity to participate in public life that provided a stimulus for the brilliant unfolding of classical Greek culture.
R40P2
Latitude and BiodiversityWhen we look at the way in which biodiversity (biological diversity) is distributed over the land surface of the planet, we find that it is far from even. The tropics contain many more species overall than an equivalent area at the higher latitudes. This seems to be true for many different groups of animals and plants.
Why is it that higher latitudes have lower diversities than the tropics? Perhaps it is simply a matter of land area. The tropics contain a larger surface area of land than higher latitudes—a fact that is not always evident when we examine commonly used projections of Earth's curved surface, since this tends to exaggerate the areas of land in the higher latitudes-and some biogeographers regard the differences in diversity as a reflection of this effect. But an analysis of the data by biologist Klaus Rohde does not support this explanation. Although area may contribute to biodiversity, it is certainly not the whole story; otherwise, large landmasses would always be richer in species.
Productivity seems to be involved instead, though perhaps its influence is indirect. Where conditions are most suitable for plant growth—that is, where temperatures are relatively high and uniform and where there is an ample supply of water-one usually finds large masses of vegetation. This leads to a complex structure in the layers of plant material. In a tropical rain forest, for example, a very large quantity of plant material builds up above the surface of the ground. There is also a large mass of material, developed below ground as root tissues, but this is less apparent. Careful analysis of the above ground material reveals that it is arranged in a series of layers, the precise number of layers varying with age and the nature of the forest. The arrangement of the biological mass (biomass) of the vegetation into layered forms is termed as "structure" (as opposed to its "composition", which refers to the species of organisms forming the community). Structure is essentially the architecture of vegetation, and as in the case of some tropical forests, it can be extremely complicated. In a mature floodplain tropical forest in the Amazon River basin, the canopy (the uppermost layers of a forest, formed by the crowns of trees) takes on a stratified structure. There are three clear peaks in leaf cover at heights of approximately 3,6, and 30 meters above the ground; and the very highest layer, at 50 meters, corresponds to the very tall trees that stand free of the main canopy and form an open layer of their own. So, such a forest contains essentially four layers of canopy. Forests in temperate lands often have just two canopy layers, so they have much less complex architecture.
Structure has a strong influence on the animal life inhabiting a site, it forms the spatial environment within which an animal feeds, moves around, shelters, Ives, and breeds. It even affects the climate on a very local level (the "microclimate') by influencing light intensity, humidity, and both the range and extremes of temperature. An area of grassland vegetation with very simple structure, for example, has a very differed microclimate at the ground level from that experienced in the upper canopy. Wind speeds are lower, temperatures are lower during the day (but warmer at night), and the relative humidity is much greater near the ground. The complexity of the microclimate is closely related to the complexity of structure in vegetation, and generally speaking, the more complex the structure of vegetation, the more species of animal are able to make a living there. The high plant biomass of the tropics leads to a greater spatial complexity in the environment, and this leads to a higher potential for diversity in the living things that can occupy a region. The climates of the higher latitudes are generally less favorable for the accumulation of large quantities of biomass; hence, the structure of vegetation is simpler and the animal diversity is consequently lower.
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Amphibian ThermoregulationIn contrast to mammals and birds, amphibians are unable to produce thermal energy through their metabolic activity, which would allow them to regulate their body temperature independent of the surrounding or ambient temperature. However, the idea that amphibians have no control whatsoever over their body temperature has been proven false because their body temperature does not always correspond to the surrounding temperature. While amphibians are poor thermoregulators, they do exercise control over their body temperature to a limited degree.
Physiological adaptations can assist amphibians in colonizing habitats where extreme conditions prevail. The tolerance range in body temperature represents the range of temperatures within which a species can survive. One species of North American newt is still active when temperatures drop to -2°C while one South American frog feels comfortable even when temperatures rise to 41°C—the highest body temperature measured in a free-ranging amphibian. Recently it has been shown that some North American frog and toad species can survive up to five days with a body temperature of -6°C with approximately one-third of their body fluids frozen. The other tissues are protected because they contain the frost-protective agents glycerin or glucose. Additionally, in many species the tolerance boundaries are flexible and can change as a result of acclimatization (long-term exposure to particular conditions).
Frog species that remain exposed to the sun despite high diurnal (daytime) temperatures exhibit some fascinating modifications in the skin structure that function as morphological adaptations. Most amphibian skin is fully water permeable and is therefore not a barrier against evaporation or solar radiation. The African savanna frog Hyperolius viridiflavus stores guanine crystals in its skin, which enable it to better reflect solar radiation, thus providing protection against overheating. The tree frog Phyllomedusa sauvager responds to evaporative losses with gland secretions that provide a greasy film over its entire body that helps prevent desiccation (dehydration).
However, behavior is by far the most important factor in thermoregulation. The principal elements in behavioral thermoregulation are basking (heliothermy), heat exchange with substrates such as rock or earth (thigmothermy), and diurnal and annual avoidance behaviors, which include moving to shelter during the day for cooling and hibernating or estivating (reducing activity during cold or hot weather, respectively) Heliothermy is especially common among frogs and toads: it allows them to increase their body temperature by more than 10°C. The Andean toad Bufo spinulosus exposes itself immediately after sunrise on moist ground and attains its preferred body temperature by this means, long before either ground or air is correspondingly warmed. A positive side effect of this approach is that it accelerates the digestion of the prey consumed overnight, thus also accelerating growth. Thigmothermy is a behavior present in most amphibians, although pressing against the ground serves a dual purpose heat absorption by conductivity and water absorption through the skin. The effect of thigmothermy is especially evident in the Andean toad during rainfall: its body temperature corresponds to the temperature of the warm earth and not to the much cooler air temperature.
Avoidance behavior occurs whenever physiological and morphological adaptations are insufficient to maintain body temperature within the vital range. Nocturnal activity in amphibians with low tolerance for high ambient temperatures is a typical thermoregulatory behavior of avoidance. Seasonal avoidance behavior is extremely important in many amphibians. Species whose habitat lies in the temperate latitudes are confronted by lethal low temperatures in winter, while species dwelling in semi-arid and arid regions are exposed to long dry, hot periods in summer.
In amphibians hibernation occurs in mud or deep holes away from frost North of the Pyrenees Mountains, the natterjack toad offers a good example of hibernation, passing the winter dug deep into sandy ground. Conversely, natterjacks in southern Spain remain active during the mild winters common to the region and are instead forced into inactivity during the dry, hot summer season. Summer estivation also occurs by burrowing into the ground or hiding in cool, deep rock crevasses to avoid desiccation and lethal ambient temperature. Amphibians are therefore hardly at mercy of ambient temperature, since by means of the mechanisms described above they are more than exercising some control over their body temperature.
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Navajo ArtThe Navajo, a Native American people living in the southwestern United States, live in small scattered settlements. In many respects, such as education, occupation, and leisure activities, their life is like that of other groups that contribute to the diverse social fabric of North American culture in the twenty-first century. At the same time, they have retained some traditional cultural practices that are associated with particular art forms. For example, the most important traditional Navajo rituals include the production of large floor paintings. These are actually made by pouring thin, finely controlled streams of colored sands or pulverized vegetable and mineral substances, pollen, and flowers in precise patterns on the ground. The largest of these paintings may be up to 5.5 meters in diameter and cover the entire floor of a room. Working from the inside of the design outward, the Navajo artist and his assistants will sift the black, white, bluish-gray, orange, and red materials through their fingers to create the finely detailed imagery. The paintings and chants used in the ceremonies are directed by well-trained artists and singers who enlist the aid of spirits who are impersonated by masked performers. The twenty-four known Navajo chants can be represented by up to 500 sand paintings. These complex paintings serve as memory aids to guide the singers during the performance of the ritual songs, which can last up to nine days.
The purpose and meaning of the sand paintings can be explained by examining one of the most basic ideals of Navajo society, embodied in their word hozho (beauty or harmony, goodness, and happiness). It coexists with hochxo ("ugliness," or "evil," and "disorder") in a world where opposing forces of dynamism and stability create constant change. When the world, which was created in beauty, becomes ugly and disorderly, the Navajo gather to perform rituals with songs and make sand paintings to restore beauty and harmony to the world. Some illness is itself regarded as a type of disharmony. Thus, the restoration of harmony through a ceremony can be part of a curing process.
Men make sand paintings that are accurate copies of paintings from the past. The songs sung over the paintings are also faithful renditions of songs from the past. By re-creating these arts, which reflect the original beauty of creation, the Navajo bring beauty to the present world. As relative newcomers to the Southwest, a place where their climate, neighbors, and rulers could be equally inhospitable, the Navajo created these art forms to affect the world around them, not just through the recounting of the actions symbolized, but through the beauty and harmony of the artworks themselves. The paintings generally illustrate ideas and events from the life of a mythical hero, who, after being healed by the gods, gave gifts of songs and paintings. Working from memory, the artists re-create the traditional form of the image as accurately as possible.
The Navajo are also world-famous for the designs on their woven blankets. Navajo women own the family flocks, control the shearing of the sheep, the carding, the spinning, and dying of the thread, and the weaving of the fabrics. While the men who make faithful copies of sand paintings from the past represent the principle of stability in Navajo thought, women embody dynamism and create new designs for every weaving they make. Weaving is a paradigm of the creativity of a mythic ancestor named Spider Woman who wove the universe as a cosmic web that united earth and sky. It was she who, according to legend, taught Navajo women how to weave. As they prepare their materials and weave, Navajo women imitate the transformations that originally created the world. Working on their looms, Navajo weavers create images through which they experience harmony with nature. lt is their means of creating beauty and thereby contributing to the beauty, harmony, and healing of the world. Thus, weaving is a way of seeing the world and being part of it.
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Climate of VenusEarth has abundant water in its oceans but very little carbon dioxide in its relatively thin atmosphere. By contrast, Venus is very dry and its thick atmosphere is mostly carbon dioxide. The original atmospheres of both Venus and Earth were derived at least in part from gases spewed forth, or outgassed, by volcanoes. The gases that emanate from present-day volcanoes on Earth, such as Mount Saint Helens, are predominantly water vapor, carbon dioxide, and sulfur dioxide. These gases should therefore have been important parts of the original atmospheres of both Venus and Earth. Much of the water on both planets is also thought to have come from impacts from comets, icy bodies formed in the outer solar system.
In fact, water probably once dominated the Venusian atmosphere. Venus and Earth are similar in size and mass, so Venusian volcanoes may well have outgassed as much water vapor as on Earth, and both planets would have had about the same number of comets strike their surfaces. Studies of how stars evolve suggest that the early Sun was only about 70 percent as luminous as it is now, so the temperature in Venus' early atmosphere must have been quite a bit lower. Thus water vapor would have been able to liquefy and form oceans on Venus. But if water vapor and carbon dioxide were once so common in the atmospheres of both Earth and Venus, what became of Earth's carbon dioxide? And what happened to the water on Venus?
The answer to the first question is that carbon dioxide is still found in abundance on Earth, but now, instead of being in the form of atmospheric carbon dioxide, it is either dissolved in the oceans or chemically bound into carbonate rocks, such as the limestone and marble that formed in the oceans. If Earth became as hot as Venus, much of its carbon dioxide would be boiled out of the oceans and baked out of the crust. Our planet would soon develop a thick, oppressive carbon dioxide atmosphere much like that of Venus.
To answer the question about Venus' lack of water, we must return to the early history of the planet. Just as on present-day Earth, the oceans of Venus limited the amount of atmospheric carbon dioxide by dissolving it in the oceans and binding it up in carbonate rocks. But being closer to the Sun than Earth is, enough of the liquid water on Venus would have vaporized to create a thick cover of water vapor cIouds. Since water vapor is a greenhouse gas, this humid atmosphere, perhaps denser than Earth's present-day atmosphere, but far less dense than the atmosphere that envelops Venus today would have efficiently trapped heat from the Sun. At first, this would have had little effect on the oceans of Venus. Although the temperature would have climbed above 100° C, the boiling point of water at sea level on Earth, the added atmospheric pressure from water vapor would have kept the water in Venus' oceans in the liquid state.
This hot and humid state of affairs may have persisted for several hundred million years. But as the Sun's energy output slowly increased over time, the temperature at the surface would eventually have risen above 374°C. Above this temperature, no matter what the atmospheric pressure, Venus' oceans would have begun to evaporate, and the added water vapor in the atmosphere would have increased the greenhouse effect.This would have made the temperature even higher and caused the oceans to evaporate faster, producing more water vapor. That, in turn, would have further intensified the greenhouse effect and made the temperature climb higher still.
Once Venus' oceans disappeared, so did the mechanism for removing carbon dioxide from the atmosphere. With no oceans to dissolve it, outgassed carbon dioxide began to accumulate in the atmosphere, intensifying the greenhouse effect even more. Temperatures eventually became high enough to "bake out" any carbon dioxide that was trapped in carbonate rocks. This liberated carbon dioxide formed the thick atmosphere of present-day Venus. Over time, the rising temperatures would have leveled off, solar ultraviolet radiation having broken down atmospheric water vapor molecules into hydrogen and oxygen, With all the water vapor gone, the greenhouse effect would no longer have accelerated.
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Trade and Early State FormationBartering was a basic trade mechanism for many thousands of years; often sporadic and usually based on notions of reciprocity, it involved the mutual exchange of commodities or objects between individuals or groups. Redistribution of these goods through society lay in the hands of chiefs, religious leaders, or kin groups. Such redistribution was a basic element in chiefdoms. The change from redistribution to formal trade—often based on regulated commerce that perhaps involved fixed prices and even currency—was closely tied to growing political and social complexity and hence to the development of the state in the ancient world.
In the 1970s, a number of archaeologists gave trade a primary role in the rise of ancient states. British archaeologist Colin Renfrew attributed the dramatic flowering of the Minoan civilization on Crete and through the Aegean to intensified trading contacts and to the impact of olive and vine cultivation on local communities. As agricultural economies became more diversified and local food supplies could be purchased both locally and over longer distances, a far-reaching economic interdependence resulted. Eventually, this led to redistribution systems for luxuries and basic commodities, systems that were organized and controlled by Minoan rulers from their palaces. As time went on, the self-sufficiency of communities was replaced by mutual dependence. Interest in long-distance trade brought about some cultural homogeneity from trade and gift exchange, and perhaps even led to piracy. Thus, intensified trade and interaction, and the flowering of specialist crafts, in a complex process of positive feedback, led to much more complex societies based on palaces, which were the economic hubs of a new Minoan civilization.
Renfrew's model made some assumptions that are now discounted. For example, he argued that the introduction of domesticated vines and olives allowed a substantial expansion of land under cultivation and helped to power the emergence of complex society. Many archaeologists and paleobotanists now question this view, pointing out that the available evidence for cultivated vines and olives suggests that they were present only in the later Bronze Age. Trade, nevertheless, was probably one of many variables that led to the emergence of palace economies in Minoan Crete.
American archaeologist William Rathje developed a hypothesis that considered an explosion in long-distance exchange a fundamental cause of Mayan civilization in Mesoamerica. He suggested that the lowland Mayan environment was deficient in many vital resources, among them obsidian, salt, stone for grinding maize, and many luxury materials. All these could be obtained from the nearby highlands, from the Valley of Mexico, and from other regions, if the necessary trading networks came into being. Such connections, and the trading expeditions to maintain them, could not be organized by individual villages. The Maya lived in a relatively uniform environment, where every community suffered from the same resource deficiencies. Thus, argued Rathje, long-distance trade networks were organized through local ceremonial centers and their leaders. In time, this organization became a state, and knowledge of its functioning was exportable, as were pottery, tropical bird feathers, specialized stone materials, and other local commodities.
Rathje's hypothesis probably explains part of the complex process of Mayan state formation, but it suffers from the objection that suitable alternative raw materials can be found in the lowlands. It could be, too, that warfare became a competitive response to population growth and to the increasing scarcity of prime agricultural land, and that it played an important role in the emergence of the Mayan states.
Now that we know much more about ancient exchange and commerce, we know that, because no one aspect of trade was an overriding cause of cultural change or evolution in commercial practices, trade can never be looked on as a unifying factor or as a primary agent of ancient civilization. Many ever-changing variables affected ancient trade, among them the demand for goods. There were also the logistics of transportation, the extent of the trading network, and the social and political environment. Intricate market networks channeled supplies along well-defined routes. Authorities at both ends might regulate the profits fed back to the source, providing the incentive for further transactions. There may or may not have been a market organization. Extensive long-distance trade was a consequence rather than a cause of complex societies.
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Geographic Isolation of SpeciesBiologist Ernst Mayr defined a species as "an actually or potentially interbreeding population that does not interbreed with other such populations when there is opportunity to do so." A key event in the origin of many species is the separation of a population with its gene pool (all of the genes in a population at any one time) from other populations of the same species, thereby preventing population interbreeding. With its gene pool isolated, a separate population can follow its own evolutionary course. In the formation of many species, the initial isolation of a population seems to have been a geographic barrier. This mode of evolving new species is called allopatric speciation.
Many factors can isolate a population geographically. A mountain range may emerge and gradually split a population of organisms that can inhabit only lowland lakes; certain fish populations might become isolated in this way. Similarly, a creeping glacier may gradually divide a population, or a land bridge such as the Isthmus of Panama may form and separate the marine life in the ocean waters on either side.
How formidable must a geographic barrier be to keep populations apart? It depends on the ability of the organisms to move across barriers. Birds and coyotes can easily cross mountains and rivers. The passage of wind-blown tree pollen is also not hindered by such barriers, and the seeds of many plants may be carried back and forth on animals. In contrast, small rodents may find a deep canyon or a wide river an effective barrier. For example, the Grand Canyon, in the southwestern United States, separates the range of the white-tailed antelope squirrel from that of the closely related Harris’ antelope squirrel. Smaller, with a shorter tail that is white underneath, the white. tailed antelope squirrel inhabits deserts north of the canyon and west of the Colorado River in southern California. Harris’ antelope squirrel has a more limited range in deserts south of the Grand Canyon.
Geographic isolation creates opportunities for new species to develop, but it does not necessarily lead to new species because speciation occurs only when the gene pool undergoes enough changes to establish reproductive barriers between the isolated population and its parent population. The likelihood of allopatric speciation increases when a population is small as well as isolated, making it more likely than a large population to have its gene pool changed substantially. For example, in less than two million years, small populations of stray animals and plants from the South American mainland that managed to colonize the Galapagos Islands gave rise to all the species that now inhabit the islands
When oceanic islands are far enough apart to permit populations to evolve in isolation, but close enough to allow occasional dispersions to occur, they are effectively outdoor laboratories of evolution. The Galapagos island chain is one of the world’s greatest showcases of evolution. Each island was born from underwater volcanoes and was gradually covered by organisms derived from strays that rode the ocean currents and winds from other islands and continents. Organisms can also be carried to islands by other organisms, such as sea birds that travel long distances with seeds clinging to their feathers.
The species on the Galapagos Islands today, most of which occur nowhere else, descended from organisms that floated, flew, or were blown over the sea from the South American mainland. For instance, the Galapagos island chain has a total of thirteen species of closely related birds called Galapagos finches. These birds have many similarities but differ in their feeding habits and their beak type, which is correlated with what they eat. Accumulated evidence indicates that all thirteen finch species evolved from a single small population of ancestral birds that colonized one of the islands. Completely isolated on the island after migrating from the mainland, the founder population may have undergone significant changes in its gene pool and become a new species. Later, a few individuals of this new species may have been blown by storms to a neighboring island.Isolated on this second island, the second founder population could have evolved into a second new species, which could later recolonize the island from which its founding population emigrated. Today each Galapagos island has multiple species of finches, with as many as ten on some islands.
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Explaining Dinosaur ExtinctionDinosaurs rapidly became extinct about 65 million years ago as part of a mass extinction known as the K-T event, because it is associated with a geological signature known as the K-T boundary, usually a thin band of sedimentation found in various parts of the world (K is the traditional abbreviation for the Cretaceous, derived from the German name Kreidezeit). Many explanations have been proposed for why dinosaurs became extinct. For example, some have blamed dinosaur extinction on the development of flowering plants, which were supposedly more difficult to digest and could have caused constipation or indigestion-except that flowering plants first evolved in the Early Cretaceous, about 60 million years before the dinosaurs died out. In fact, several scientists have suggested that the duckbill dinosaurs and horned dinosaurs, with their complex battery of grinding teeth, evolved to exploit this new resource of rapidly growing flowering plants. Others have blamed extinction on competition from the mammals, which allegedly ate all the dinosaur eggs-except that mammals and dinosaurs appeared at the same time in the Late Triassic, about 190 million years ago, and there is no reason to believe that mammals suddenly acquired a taste for dinosaur eggs after 120 million years of coexistence. Some explanations (such as the one stating that dinosaurs all died of diseases) fail because there is no way to scientifically test them, and they cannot move beyond the realm of speculation and guesswork.
This focus on explaining dinosaur extinction misses an important point: the extinction at the end of the Cretaceous was a global event that killed off organisms up and down the food chain. It wiped out many kinds of plankton in the ocean and many marine organisms that lived on the plankton at the base of the food chain. These included a variety of clams and snails, and especially the ammonites, a group of shelled squidlike creatures that dominated the Mesozoic seas and had survived many previous mass extinctions. The K-T event marked the end of the marine reptiles, such as the mosasaurs and the plesiosaurs, which were the largest creatures that had ever lived in the seas and which ruled the seas long before whales evolved. On land, there was also a crisis among the land plants, in addition to the disappearance of dinosaurs. So any event that can explain the destruction of the base of the food chain (plankton in the ocean, plants on land) can better explain what happened to organisms at the top of the food chain, such as the dinosaurs. By contrast, any explanation that focuses strictly on the dinosaurs completely misses the point. The Cretaceous extinctions were a global phenomenon, and dinosaurs were just a part of a bigger picture.
According to one theory, the Age of Dinosaurs ended suddenly 65 million years ago when a giant rock from space plummeted to Earth. Estimated to be ten to fifteen kilometers in diameter, this bolide (either a comet or an asteroid) was traveling at cosmic speeds of 20-70 kilometers per second, or 45,000-156,000 miles per hour. Such a huge mass traveling at such tremendous speeds carries an enormous amount of energy. When the bolide struck, this energy was released and generated a huge shock wave that leveled everything for thousands of kilometers around the impact and caused most of the landscape to burst into flames. The bolide struck an area of the Yucatan Peninsula of Mexico known as Chicxulub, excavating a crater 15-20 kilometers deep and at least 170 kilometers in diameter. The impact displaced huge volumes of seawater, causing much flood damage in the Caribbean. Meanwhile, the bolide itself excavated 100 cubic kilometers of rock and debris from the site, which rose to an altitude of 100 kilometers. Most of it fell back immediately, but some of it remained as dust in the atmosphere for months. This material, along with the smoke from the Gres, shrouded Earth, creating a form of nuclear winter. According to computerized climate models, global temperatures fell to near the freezing point, photosynthesis halted, and most plants on land and in the sea died. With the bottom of the food chain destroyed, dinosaurs could not survive.
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Callisto and GanymedeFrom 1996 to 1999, the Galileo spacecraft passed through the Jovian system, providing much information about Jupiter’s satellites. Callisto, the outermost of Jupiter’s four largest satellites, orbits the planet in seventeen days at a distance from Jupiter of two million kilometers. Like our own Moon, Callisto rotates in the same period as it revolves, so it always keeps the same face toward Jupiter. Its noontime surface temperature is only about -140°C, so water ice is stable on its surface year-round. Callisto has a diameter of 4,820 kilometers, almost the same as that of Mercury. Its mass is only one-third as great, which means its density must be only one third as great as well. This tells us that Callisto has far less of the rocky metallic materials found in the inner planets and must instead be an icy body through much of its interior.
Callisto has not fully differentiated, meaning separated into layers of different density materials. Astronomers can tell that it lacks a dense core from the details of its gravitational pull on the Galileo spacecraft during several very close flybys. This fact surprised scientists, who expected that all the big icy moons would be differentiated. lt is much easier for an icy body to differentiate than for a rocky one, since the melting temperature of ice is so low. Only a little heating will soften the ice and get the process started, allowing the rock and metal to sink to the center and the slushy ice to float to the surface. Yet Callisto seems to have frozen solid before the process of differentiation was complete.
Like our Moon’s highlands, the surface of Callisto is covered with impact craters.The survival of these craters tells us that an icy object can form and retain impact craters in its surface. In thinking of ice so far from the Sun, it is important not to judge its behavior from that of the much warmer ice we know on Earth; at the temperatures of the outer solar system, ice on the surface is nearly as hard as rock, and behaves similarly. Ice on Callisto does not deform or flow like ice in glaciers on Earth. Callisto is unique among the planet-sized objects of the solar system in its absence of interior forces to drive geological evolution. The satellite was born dead and has remained geologically dead for more than four billion years.
Ganymede, another of Jupiter’s satellites and the largest in our solar system, is also cratered, but less so than Callisto. About one-quarter of its surface seems to be as old and heavily cratered; the rest formed more recently, as we can tell by the sparse covering of impact craters as well as the relative freshness of the craters. Ganymede is a differentiated world, like the terrestrial planets. Measurements of its gravity field tell us that the rock and metal sank to form a core about the size of our Moon, with a mantle and crust of ice floating above it. In addition, the Galileo spacecraft discovered that Ganymede has a magnetic held, the signature of a partially molten interior. Ganymede is not a dead world, but rather a place of continuing geological activity powered by an internal heat source. Much of its surface may be as young as half a billion years.
The younger terrain is the result of tectonic and volcanic forces. Some features formed when the crust cracked, flooding many of the craters with water from the interior. Extensive mountain ranges were formed from compression of the crust, forming long ridges with parallel valleys spaced one to two kilometers apart. In some places older impact craters were split and pulled apart. There are even indications of large-scale crustal movements that are similar to the plate tectonics of Earth.
Why is Ganymede different from Callisto? Possibly the small difference in size and internal heating between the two led to this divergence in their evolution. But more likely the gravity of Jupiter is to blame for Ganymede’s continuing geological activity. Ganymede is close enough to Jupiter that tidal forces from the giant planet may have episodically heated its interior and triggered major convulsions on its crust.
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The Empire of Alexander the GreatIn 334 B.C. Alexander the Great took his Greek armies to the east and in only a few years completed his creation of an empire out of much of southwest Asia. In the new empire, barriers to trade and the movement of peoples were removed; markets were put in touch with one another. In the next generation thousands of Greek traders and artisans would enter this wider world to seek their fortunes. Alexander's actions had several important consequences for the region occupied by the empire.
The first of these was the expansion of Greek civilization throughout the Middle East. Greek became the great international language. Towns and cities were established not only as garrisons (military posts) but as centers for the diffusion of Greek language, literature, and thought, particularly through libraries, as at Antioch (in modern Turkey) and the most famous of all, at Alexandria in Egypt, which would be the finest in the world for the next thousand years.
Second, this internationalism spelled the end of the classical Greek city-state——the unit of government in ancient Greece——and everything it stood for. Most city-states had been quite small in terms of citizenry, and this was considered to be a good thing. The focus of life was the agora, the open marketplace where assemblies could be held and where issues of the day, as well as more fundamental topics such as the purpose of government or the relationship between law and freedom, could be discussed and decisions made by individuals in person.The philosopher Plato(428-348 B.C.) felt that the ideal city-state should have about 5,000 citizens, because to the Greeks it was important that everyone in the community should know each other. In decision making, the whole body of citizens together would have the necessary knowledge in order generally to reach the right decision, even though the individual might not be particularly qualified to decide. The philosopher Aristotle (384-322 B.C.), who lived at a time when the city-state system was declining, believed that a political entity of 100,000 simply would not be able to govern itself.
This implied that the city-state was based on the idea that citizens were not specialists but had multiple interests and talents——each a so-called jack-of-all-trades who could engage in many areas of life and politics. It implied a respect for the wholeness of life and a consequent dislike of specialization. It implied economic and military self-sufficiency.But with the development of trade and commerce in Alexander's empire came the growth of cities; it was no longer possible to be a jack-of-all-trades. One now had to specialize, and with specialization came professionalism. There were getting to be too many persons to know, an easily observable community of interests was being replaced by a multiplicity of interests. The city-state was simply too "small-time."
Third, Greek philosophy was opened up to the philosophy and religion of the East. At the peak of the Greek city-state, religion played an important part. Its gods—such as Zeus, father of the gods, and his wife Hera—were thought of very much as being like human beings but with superhuman abilities. Their worship was linked to the rituals connected with one's progress through life—birth, marriage, and death— and with invoking protection against danger, making prophecies, and promoting healing, rather than to any code of behavior. Nor was there much of a theory of afterlife.
Even before Alexander's time, a life spent in the service of their city-state no longer seemed ideal to Greeks. The Athenian philosopher Socrates (470-399 B.C.) was the first person in Greece to propose a morality based on individual conscience rather than the demands of the state, and for this he was accused of not believing in the city's gods and so corrupting the youth, and he was condemned to death. Greek philosophy—or even a focus on conscience—might complement religion but was no substitute for it, and this made Greeks receptive to the religious systems of the Middle East, even if they never adopted them completely. The combination of the religious instinct of Asia with the philosophic spirit of Greece spread across the world in the era after Alexander's death, blending the culture of the Middle East with the culture of Greece.
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The Origin of PetroleumPetroleum is defined as a gaseous, liquid, and semisolid naturally occurring substance that consists chiefly of hydrocarbons (chemical compounds of carbon and hydrogen). Petroleum is therefore a term that includes both oil and natural gas. Petroleum is nearly always found in marine sedimentary rocks. In the ocean, microscopic phytoplankton (tiny floating plants) and bacteria (simple, single-celled organisms) are the principal sources of organic matter that is trapped and buried in sediment. Most of the organic matter is buried in clay that is slowly converted to a fine-grained sedimentary rock known as shale. During this conversion, organic compounds are transformed to oil and natural gas.
Sampling on the continental shelves and along the base of the continental slopes has shown that fine muds beneath the seafloor contain up to 8 percent organic matter. Two additional kinds of evidence support the hypothesis that petroleum is a product of the decomposition of organic matter: oil possesses optical properties known only in hydrocarbons derived from organic matter, and oil contains nitrogen and certain compounds believed to originate only in living matter. A complex sequence of chemical reactions is involved in converting the original solid organic matter to oil and gas, and additional chemical changes may occur in the oil and gas even after they have formed.
It is now well established that petroleum migrates through aquifers and can become trapped in reservoirs. Petroleum migration is analogous to groundwater migration. When oil and gas are squeezed out of the shale in which they originated and enter a body of sandstone or limestone somewhere above, they migrate readily because sandstones (consisting of quartz grains) and limestones (consisting of carbonate minerals) are much more permeable than any shale. The force of molecular attraction between oil and quartz or carbonate minerals is weaker than that between water and quartz or carbonate minerals. Hence, because oil and water do not mix, water remains fastened to the quartz or carbonate grains, while oil occupies the central parts of the larger openings in the porous sandstone or limestone. Because oil is lighter than water, it tends to glide upward past the carbonate- and quartz-held water. In this way, oil becomes segregated from the water; when it encounters a trap, it can form a pool.
Most of the petroleum that forms in sediments does not find a suitable trap and eventually makes its way, along with groundwater, to the surface of the sea. It is estimated that no more than 0.1 percent of all the organic matter originally buried in a sediment is eventually trapped in an oil pool. It is not surprising, therefore, that the highest ratio of oil and gas pools to volume of sediment is found in rock no older than 2.5 million years—young enough so that little of the petroleum has leaked away—and that nearly 60 percent of all oil and gas discovered so far has been found in strata that formed in the last 65 million years This does not mean that older rocks produced less petroleum; it simply means that oil in older rocks has had a longer time in which to leak away.
How much oil is there in the world? This is an extremely controversial question. Many billions of barrels of oil have already been pumped out of the ground. A lot of additional oil has been located by drilling but is still waiting to be pumped out. Possibly a great deal more oil remains to be found by drilling. Unlike coal, the volume of which can be accurately estimated, the volume of undiscovered oil can only be guessed at. Guesses involve the use of accumulated experience from a century of drilling. Knowing how much oil has been found in an intensively drilled area, such as eastern Texas, experts make estimates of probable volumes in other regions where rock types and structures are similar to those in eastern Texas. Using this approach and considering all the sedimentary basins of the world, experts estimate that somewhere between 1,500 and 3,000 billion barrels of oil will eventually be discovered.
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El NifioThe cold Humboldt Current of the Pacific Ocean flows toward the equator along the coasts of Ecuador and Peru in South America. When the current approaches the equator, the westward-flowing trade winds cause nutrient-rich cold water along the coast to rise from deeper depths to more shallow ones. This upwelling of water has economic repercussions. Fishing, especially for anchovies, is a major local industry.
Every year during the months of December and January, a weak, warm countercurrent replaces the normally cold coastal waters. Without the upwelling of nutrients from below to feed the fish, fishing comes to a standstill. Fishers in this region have known the phenomenon for hundreds of years. In fact, this is the time of year they traditionally set aside to tend to their equipment and await the return of cold water. The residents of the region have given this phenomenon the name of El Nifio, which is Spanish for "the child," because it occurs at about the time of the celebration of birth of the Christ child.
While the warm-water countercurrent usually lasts for two months or less, there are occasions when the disruption to the normal flow lasts for many months. In these situations, water temperatures are raised not just along the coast, but for thousands of kilometers offshore. Over the last few decades, the term El Nifio has come to be used to describe these exceptionally strong episodes and not the annual event. During the past 60 years, at least ten El Nifios have been observed Not only do El Niftos affect the temperature of the equatorial Pacific, but the strongest of them impact global weather.
The processes that interact to produce an El Nifio involve conditions all across the Pacific, not just in the waters off South America. Over 60 years ago, Sir Gilbert Walker, a British scientist, discovered a connection between surface pressure readings at weather stations on the eastern and western sides of the Pacific. He noted that a rise in atmospheric pressure in the eastern Pacific is usually accompanied by a fall in pressure in the western Pacific and vice versa. He called this seesaw pattern the Southern Oscillation. It was later realized that there is a close link between El Nino and the Southern Oscillation. In fact, the link between the two is so great that they are often referred to jointly as ENSO (El Nino-Southern Oscillation).
During a typical year, the eastern Pacific has a higher pressure than the western Pacific does. This east-to-west pressure gradient enhances the trade winds over the equatorial waters. This results in a warm surface current that moves east to west at the equator. The western Pacific develops a thick, warm layer of water while the eastern Pacific has the cold Humboldt Current enhanced by upwelling. However, in other years the Southern Oscillation, for unknown reasons, swings in the opposite direction, dramatically changing the usual conditions described above, with pressure increasing in the western. Pacific and decreasing in the eastern Pacific. This change in the pressure gradient causes the trade winds to weaken or, in some cases, to reverse. This then causes the warm water in the western Pacific to flow eastward, increasing sea-surface temperatures in the central and eastern Pacific. The eastward shift signals the beginning of an El Nifio.
Scientists try to document as many past El Nino events as possible by piecing together bits of historical evidence, such as sea-surface temperature records, daily observations of atmospheric pressure and rainfall, fisheries’ records from South America, and the writings of Spanish colonists dating back to the fifteenth century. From such historical evidence we know that El Nirtos have occurred as far back as records go. It would seem that they are becoming more frequent. Records indicate that during the sixteenth century, an El Nino occurred on average every six years. Evidence gathered over the past few decades indicates that El Ninos are now occurring on average a little over every two years. Even more alarming is the fact that they appear to be getting stronger. The 1997-1998 El Nifio brought copious and damaging rainfall to the southern United States, from California to Florida. Snowstorms in the northeast portion of the United States were more frequent and intense than in most years.
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From Fish to Terrestrial VertebratesOne of the most significant evolutionary events that occurred on Earth was the transition of water-dwelling fish to terrestrial tetrapods (four-limbed organisms with backbones). Fish probably originated in the oceans, and our first records of them are in marine rocks. However, by the Devonian Period (408 million to 362 million years ago), they had radiated into almost all available aquatic habitats, including freshwater settings. One of the groups whose fossils are especially common in rocks deposited in fresh water is the lobe-finned fish.
The freshwater Devonian lobe-finned fish rhipidistian crossopterygian is of particular interest to biologists studying tetrapod evolution. These fish lived in river channels and lakes on large deltas. The delta rocks in which these fossils are found are commonly red due to oxidized iron minerals, indicating that the deltas formed in a climate that had alternate wet and dry periods. If there were periods of drought, any adaptations allowing the fish to survive the dry conditions would have been advantageous. In these rhipidistians，several such adaptations existed. It is known that they had lungs as well as gills for breathing. Cross sections cut through some of the fossils reveal that the mud filling the interior of the carcass differed in consistency and texture depending on its location inside the fish. These differences suggest a saddlelike cavity below the front end of the gut that can only be interpreted as a lung. Gills were undoubtedly the main source of oxygen for these fish, but the lungs served as an auxiliary breathing device for gulping air when the water became oxygen depleted, such as during extended periods of drought. So, these fish had already evolved one of the prime requisites for living on land: the ability to use air as a source of oxygen.
A second adaptation of these fish was in the structure of the lobe fins. The fins were thick, fleshy, and quite sturdy, with a median axis of bone down the center. They could have been used as feeble locomotor devices on land, perhaps good enough to allow a fish to flop its way from one pool of water that was almost dry to an adjacent pond that had enough water and oxygen for survival. These fins eventually changed into short, stubby legs. The bones of the fins of a Devonian rhipidistian exactly match in number and position the limb bones of the earliest known tetrapods, the amphibians. It should be emphasized that the evolution of lungs and limbs was in no sense an anticipation of future life on land. These adaptations developed because they helped fish to survive in their existing aquatic environment.
What ecological pressures might have caused fishes to gradually abandon their watery habitat and become increasingly land-dwelling creatures? Changes in climate during the Devonian may have had something to do with this if freshwater areas became progressively more restricted. Another impetus may have been new sources of food. The edges of ponds and streams surely had scattered dead fish and other water-dwelling creatures. In addition, plants had emerged into terrestrial habitats in areas near streams and ponds, and crabs and other arthropods were also members of this earliest terrestrial community. Thus, by the Devonian the land habitat marginal to freshwater was probably a rich source of protein that could be exploited by an animal that could easily climb out of water. Evidence from teeth suggests that these earliest tetrapods did not utilize land plants as food; they were presumably carnivorous and had not developed the ability to feed on plants.
How did the first tetrapods make the transition to a terrestrial habitat? Like early land plants such as rhyniophytes, they made only a partial transition; they were still quite tied to water. However, many problems that faced early land plants were not applicable to the first tetrapods. The ancestors of these animals already had a circulation system, and they were mobile, so that they could move to water to drink. Furthermore, they already had lungs, which rhipidistians presumably used for auxiliary breathing. The principal changes for the earliest tetrapods were in the skeletal system—changes in the bones of the fins, the vertebral column, pelvic girdle, and pectoral girdle.
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The Use of the Camera ObscuraThe precursor of the modern camera, the camera obscura is a darkened enclosure into which light is admitted through a lens in a small hole. The image of the illuminated area outside the enclosure is thrown upside down as if by magic onto a surface in the darkened enclosure. This technique was known as long ago as the fifth century B.C. in China. Aristotle also experimented with it in the fourth century B.C., and Leonardo da Vinci described it in his notebooks in 1490. In 1558 Giovanni Battista Della Porta wrote in his twenty-volume work Magia naturalis (meaning "natural magic") instructions for adding a convex lens to improve the quality of the image thrown against a canvas or panel in the darkened area where its outlines could be traced. Later, portable camera obscuras were developed, with interior mirrors and drawing tables on which the artist could trace the image. For the artist, this technique allows forms and linear perspective to be drawn precisely as they would be seen from a single viewpoint. Mirrors were also used to reverse the projected images to their original positions.
Did some of the great masters of painting, then, trace their images using a camera obscura? Some art historians are now looking for clues of artists' use of such devices. One of the artists whose paintings are being analyzed from this point of view is the great Dutch master, Jan Vermeer, who lived from 1632 to 1675 during the flowering of art and science in the Netherlands, including the science of optics. Vermeer produced only about 30 known paintings, including his famous The Art of Painting. The room shown in it closely resembles the room in other Vermeer paintings, with lighting coming from a window on the left, the same roof beams, and similar floor tiles, suggesting that the room was fitted with a camera obscura on the side in the foreground. The map hung on the opposite wall was a real map in Vermeers possession, reproduced in such faithful detail that some kind of tracery is suspected. When one of Vermeer's paintings was X-rayed, it did not have any preliminary sketches on the canvas beneath the paint, but rather the complete image drawn in black and white without any trial sketches. Vermeer did not have any students, did not keep any records, and did not encourage anyone to visit his studio, facts that can be interpreted as protecting his secret use of a camera obscura.
In recent times the British artist David Hockney has published his investigations into the secret use of the camera obscura, claiming that for up to 400 years, many of Western art's great masters probably used the device to produce almost photographically realistic details in their paintings. He includes in this group Caravaggio, Hans Holbein, Leonardo da Vinci, Diego Velazquez, Jean-Auguste-Dominique Ingres, Agnolo Bronzino, and Jan van Eyck. From an artist's point of view, Hockney observed that a camera obscura compresses the complicated forms of a three-dimensional scene into two-dimensional shapes that can easily be traced and also increases the contrast between light and dark, leading to the chiaroscuro effect seen in many of these paintings. In Jan van Eyck's The Marriage of Giovanni Arnolfini and Giovanna Cenami, the complicated foreshortening in the chandelier and the intricate detail in the bride's garments are among the clues that Hockney thinks point to the use of the camera obscura.
So what are we to conclude? If these artists did use a camera obscura, does that diminish their stature? Hockney argues that the camera obscura does not replace artistic skill in drawing and painting. In experimenting with it, he found that it is actually quite difficult to use for drawing, and he speculates that the artists probably combined their observations from life with tracing of shapes.
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SeagrassesMany areas of the shallow sea bottom are covered with a lush growth of aquatic flowering plants adapted to live submerged in seawater. These plants are collectively called seagrasses. Seagrass beds are strongly influenced by several physical factors. The most significant is water motion: currents and waves. Since seagrass systems exist in both sheltered and relatively open areas, they are subject to differing amounts of water motion. For any given seagrass system, however, the water motion is relatively constant. Seagrass meadows in relatively turbulent waters tend to form a mosaic of individual mounds, whereas meadows in relatively calm waters tend to form flat, extensive carpets. The seagrass beds, in turn, dampen wave action, particularly if the blades reach the water surface. This damping effect can be significant to the point where just one meter into a seagrass bed the wave motion can be reduced to zero. Currents are also slowed as they move into the bed.
The slowing of wave action and currents means that seagrass beds tend to accumulate sediment. However, this is not universal and depends on the currents under which the bed exists. Seagrass beds under the influence of strong currents tend to have many of the lighter particles, including seagrass debris, moved out, whereas beds in weak current areas accumulate lighter detrital material. It is interesting that temperate seagrass beds accumulate sediments from sources outside the beds, whereas tropical seagrass beds derive most of their sediments from within.
Since most seagrass systems are depositional environments, they eventually accumulate organic material that leads to the creation of fine-grained sediments with a much higher organic content than that of the surrounding unvegetated areas. This accumulation, in turn, reduces the water movement and the oxygen supply. The high rate of metabolism (the processing of energy for survival) of the microorganisms in the sediments causes sediments to be anaerobic (without oxygen) below the first few millimeters. According to ecologist J. W. Kenworthy, anaerobic processes of the microorganisms in the sediment are an important mechanism for regenerating and recycling nutrients and carbon, ensuring the high rates of productivity—that is, the amount of organic material produced-that are measured in those beds. In contrast to other productivity in the ocean, which is confined to various species of algae and bacteria dependent on nutrient concentrations in the water column, seagrasses are rooted plants that absorb nutrients from the sediment or substrate. They are, therefore, capable of recycling nutrients into the ecosystem that would otherwise be trapped in the bottom and rendered unavailable.
Other physical factors that have an effect on seagrass beds include light, temperature, and desiccation (drying out). For example, water depth and turbidity (density of particles in the water) together or separately control the amount of light available to the plants and the depth to which the seagrasses may extend. Although marine botanist W. A. Setchell suggested early on that temperature was critical to the growth and reproduction of eelgrass, it has since been shown that this particularly widespread seagrass grows and reproduces at temperatures between 2 and 4 degrees Celsius in the Arctic and at temperatures up to 28 degrees Celsius on the northeastern coast of the United States. Still, extreme temperatures, in combination with other factors, may have dramatic detrimental effects. For example, in areas of the cold North Atlantic, ice may form in winter. Researchers Robertson and Mann note that when the ice begins to break up, the wind and tides may move the ice around, scouring the bottom and uprooting the eelgrass. In contrast, at the southern end of the eelgrass range, on the southeastern coast of the United States, temperatures over 30 degrees Celsius in summer cause excessive mortality. Seagrass beds also decline if they are subjected to too much exposure to the air. The effect of desiccation is often difficult to separate from the effect of temperature. Most seagrass beds seem tolerant of considerable changes in salinity (salt levels) and can be found in brackish (somewhat salty) waters as well as in full- strength seawater.
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The Beringia LandscapeDuring the peak of the last ice age, northeast Asia (Siberia) and Alaska were connected by a broad land mass called the Bering Land Bridge. This land bridge existed because so much of Earth's water was frozen in the great ice sheets that sea levels were over 100 meters lower than they are today. Between 25,000 and 10,000 years ago, Siberia, the Bering Land Bridge, and Alaska shared many environmental characteristics. These included a common mammalian fauna of large mammals, a common flora composed of broad grasslands as well as wind-swept dunes and tundra, and a common climate with cold, dry winters and somewhat warmer summers. The recognition that many aspects of the modern flora and fauna were present on both sides of the Bering Sea as remnants of the ice-age landscape led to this region being named Beringia.
It is through Beringia that small groups of large mammal hunters, slowly expanding their hunting territories, eventually colonized North and South America. On this archaeologists generally agree, but that is where the agreement stops. One broad area of disagreement in explaining the peopling of the Americas is the domain of paleoecologists, but it is critical to understanding human history; what was Beringia like?
The Beringian landscape was very different from what it is today. Broad, windswept valleys; glaciated mountains; sparse vegetation; and less moisture created a rather forbidding land mass. This land mass supported herds of now-extinct species of mammoth, bison, and horse and somewhat modern versions of caribou, musk ox, elk, and saiga antelope. These grazers supported in turn a number of impressive carnivores, including the giant short-faced bear, the saber-tooth cat, and a large species of lion.
The presence of mammal species that require grassland vegetation has led Arctic biologist Dale Guthrie to argue that while cold and dry, there must have been broad areas of dense vegetation to support herds of mammoth, horse, and bison. Further, nearly all of the ice-age fauna had teeth that indicate an adaptation to grasses and sedges; they could not have been supported by a modern flora of mosses and lichens. Guthrie has also demonstrated that the landscape must have been subject to intense and continuous winds, especially in winter. He makes this argument based on the anatomy of horse and bison, which do not have the ability to search for food through deep snow cover. They need landscapes with strong winds that remove the winter snows, exposing the dry grasses beneath. Guthrie applied the term "mammoth steppe" to characterize this landscape.
In contrast, Paul Colinvaux has offered a counterargument based on the analysis of pollen in lake sediments dating to the last ice age. He found that the amount of pollen recovered in these sediments is so low that the Beringian landscape during the peak of the last glaciation was more likely to have been what he termed a "polar desert" with little or only sparse vegetation. In no way was it possible that this region could have supported large herds of mammals and thus, human hunters. Guthrie has argued against this view by pointing out that radiocarbon analysis of mammoth, horse, and bison bones from Beringian deposits revealed that the bones date to the period of most intense glaciation.
The argument seemed to be at a standstill until a number of recent studies resulted in a spectacular suite of new finds. The first was the discovery of a 1,000-square-kilometer preserved patch of Beringian vegetation dating to just over 17,000 years ago-the peak of the last ice age. The plants were preserved under a thick ash fall from a volcanic eruption. Investigations of the plants found grasses, sedges, mosses, and many other varieties in a nearly continuous cover, as was predicted by Guthrie. But this vegetation had a thin root mat with no soil formation, demonstrating that there was little long-term stability in plant cover, a finding supporting some of the arguments of Colinvaux. A mixture of continuous but thin vegetation supporting herds of large mammals is one that seems plausible and realistic with the available data.
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Wind pollinationPollen, a powdery substance, which is produced by flowering plants and contains male reproductive cells, is usually carried from plant to plant by insects or birds, but some plants rely on the wind to carry their pollen. Wind pollination is often seen as being primitive and wasteful in costly pollen and yet it is surprisingly common, especially in higher latitudes. Wind is very good at moving pollen a long way; pollen can be blown for hundreds of kilometers, and only birds can get pollen anywhere near as far. The drawback is that wind is obviously unspecific as to where it takes the pollen. It is like trying to get a letter to a friend at the other end of the village by climbing onto the roof and throwing an armful of letters into the air and hoping that one will end up in the friend's garden. For the relatively few dominant tree species that make up temperate forests, where there are many individuals of the same species within pollen range, this is quite a safe gamble. If a number of people in the village were throwing letters off roofs, your friend would be bound to get one. By contrast, in the tropics, where each tree species has few, widely scattered individuals, the chance of wind blowing pollen to another individual is sufficiently slim that animals are a safer bet as transporters of pollen. Even tall trees in the tropics are usually not wind pollinated despite being in windy conditions. In a similar way, trees in temperate forests that are insect pollinated tend to grow as solitary, widely spread individuals.
Since wind-pollinated flowers have no need to attract insects or other animals, they have dispensed with bright petals, nectar, and scent. These are at best a waste and at worst an impediment to the transfer of pollen in the air. The result is insignificant-looking flowers and catkins (dense cylindrical clusters of small, petalless flowers).
Wind pollination does, of course, require a lot of pollen. Birch and hazel trees can produce 5.5 and 4 million grains per catkin, respectively. There are various adaptations to help as much of the pollen go as far as possible. Most deciduous wind-pollinated trees (which shed their leaves every fall) produce their pollen in the spring while the branches are bare of leaves to reduce the surrounding surfaces that "compete" with the stigmas (the part of the flower that receives the pollen) for pollen. Evergreen conifers, which do not shed their leaves, have less to gain from spring flowering, and, indeed, some flower in the autumn or winter.
Pollen produced higher in the top branches is likely to go farther: it is windier (and gustier) and the pollen can be blown farther before hitting the ground. Moreover, dangling catkins like hazel hold the pollen in until the wind is strong enough to bend them, ensuring that pollen is only shed into the air when the wind is blowing hard. Weather is also important. Pollen is shed primarily when the air is dry to prevent too much sticking to wet surfaces or being knocked out of the air by rain. Despite these adaptations, much of the pollen fails to leave the top branches, and only between 0.5 percent and 40 percent gets more than 100 meters away from the parent. But once this far, significant quantities can go a kilometer or more. Indeed, pollen can travel many thousands of kilometers at high altitudes. Since all this pollen is floating around in the air, it is no wonder that wind-pollinated trees are a major source of allergies.
Once the pollen has been snatched by the wind, the fate of the pollen is obviously up to the vagaries of the wind, but not everything is left to chance. Windborne pollen is dry, rounded, smooth, and generally smaller than that of insect-pollinated plants. But size is a two-edged sword. Small grains may be blown farther but they are also more prone to be whisked past the waiting stigma because smaller particles tend to stay trapped in the fast-moving air that flows around the stigma. But stigmas create turbulence, which slows the air speed around them and may help pollen stick to them.
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Feeding Strategies in the OceanIn the open sea, animals can often find food reliably available in particular regions or seasons (e.g. , in coastal areas in springtime). In these circumstances, animals are neither constrained to get the last calorie out of their diet nor is energy conservation a high priority. In contrast, the food levels in the deeper layers of the ocean are greatly reduced, and the energy constraints on the animals are much more severe. To survive at those levels, animals must maximize their energy input, finding and eating whatever potential food source may be present.
In the near-surface layers, there are many large, fast carnivores as well as an immense variety of planktonic animals, which feed on plankton (small, free-floating plants or animals) by filtering them from currents of water that pass through a specialized anatomical structure. These filter-feeders thrive in the well-iIluminated surface waters because oceans have so many very small organisms, from bacteria to large algae to larval crustaceans. Even fishes can become successful filter-feeders in some circumstances. Although the vast majority of marine fishes are carnivores, in near-surface regions of high productivity the concentrations of larger phytoplankton (the plant component of plankton) are sufficient to support huge populations of filter-feeding sardines and anchovies. These small fishes use their gill filaments to strain out the algae that dominate such areas. Sardines and anchovies provide the basis for huge commercial fisheries as well as a food resource for large numbers of local carnivores, particularly seabirds. At a much larger scale, baleen whales and whale sharks are also efficient filter-feeders in productive coastal or polar waters, although their filtered particles comprise small animals such as copepods and krill rather than phytoplankton.
Filtering seawater for its particulate nutritional content can be an energetically demanding method of feeding, particularly when the current of water to be filtered has to be generated by the organism itself, as is the case for all planktonic animals. Particulate organic matter of at least 2.5 micrograms per cubic liter is required to provide a filter-feeding planktonic organism with a net energy gain. This value is easily exceeded in most coastal waters, but in the deep sea, the levels of organic matter range from next to nothing to around 7 micrograms per cubic liter. Even though mean levels may mask much higher local concentrations, it is still the case that many deep-sea animals are exposed to conditions in which a normal filter-feeder would starve.
There are, therefore, fewer successful filter-feeders in deep water, and some of those that are there have larger filtering systems to cope with the scarcity of particles. Another solution for such animals is to forage in particular layers of water where the particles may be more concentrated. Many of the groups of animals that typify the filter-feeding lifestyle in shallow water have deep-sea representatives that have become predatory. Their filtering systems, which reach such a high degree of development in shallow-water species, are greatly reduced. Alternative methods of active or passive prey capture have been evolved, including trapping and seizing prey, entangling prey, and sticky tentacles.
In the deeper waters of the oceans, there is a much greater tendency for animals to await the arrival of food particles or prey rather than to search them out actively (thus minimizing energy expenditure). This has resulted in a more stealthy style of feeding, with the consequent emphasis on lures and/or the evolution of elongated appendages that increase the active volume of water controlled or monitored by the animal. Another consequence of the limited availability of prey is that many animals have developed ways of coping with much larger food particles, relative to their own body size, than the equivalent shallower species can process. Among the fishes there is a tendency for the teeth and jaws to become appreciably enlarged. In such creatures, not only are the teeth hugely enlarged and/or the jaws elongated but the size of the mouth opening may be greatly increased by making the jaw articulations so flexible that they can be effectively dislocated. Very large or long teeth provide almost no room for cutting the prey into a convenient size for swallowing; the fish must gulp the prey down whole.
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The Origins of WritingIt was in Egypt and Mesopotamia (modern-day Iraq) that civilization arose, and it is there that we find the earliest examples of that key feature of civilization, writing. These examples, in the form of inscribed clay tablets that date to shortly before 3000 B.C.E., have been discovered among the archaeological remains of the Sumerians, a gifted people settled in southern Mesopotamia.
The Egyptians were not far behind in developing writing, but we cannot follow the history of their writing in detail because they used a perishable writing material. In ancient times the banks of the Nile were lined with papyrus plants, and from the papyrus reeds the Egyptians made a form of paper; it was excellent in quality but, like any paper, fragile. Mesopotamia’s rivers boasted no such useful reeds, but its land did provide good clay, and as a consequence the clay tablet became the standard material. Though clumsy and bulky it has a virtue dear to archaeologists: it is durable. Fire, for example, which is death to papyrus paper or other writing materials such as leather and wood, simply bakes it hard, thereby making it even more durable. So when a conqueror set a Mesopotamian palace ablaze, he helped ensure the survival of any clay tablets in it. Clay, moreover, is cheap, and forming it into tablets is easy, factors that helped the clay tablet become the preferred writing material not only throughout Mesopotamia but far outside it as well, in Syria, Asia Minor, Persia, and even for a while in Crete and Greece. Excavators have unearthed clay tablets in all these lands. In the Near East they remained in use for more than two and a half millennia, and in certain areas they lasted down to the beginning of the common era until finally yielding, once and for all, to more convenient alternatives.
The Sumerians perfected a style of writing suited to clay. This script consists of simple shapes, basically just wedge shapes and lines that could easily be incised in soft clay with a reed or wooden stylus; scholars have dubbed it cuneiform from the wedge-shaped marks (cunei in Latin) that are its hallmark. Although the ingredients are merely wedges and lines, there are hundreds of combinations of these basic forms that stand for different sounds or words. Learning these complex signs required long training and much practice; inevitably, literacy was largely limited to a small professional class, the scribes.
The Akkadians conquered the Sumerians around the middle of the third millennium B.C.E., and they took over the various cuneiform signs used for writing Sumerian and gave them sound and word values that fit their own language. The Babylonians and Assyrians did the same, and so did peoples in Syria and Asia Minor. The literature of the Sumerians was treasured throughout the Near East, and long after Sumerian ceased to be spoken, the Babylonians and Assyrians and others kept it alive as a literary language, the way Europeans kept Latin alive after the fall of Rome. For the scribes of these non-Sumerian languages, training was doubly demanding since they had to know the values of the various cuneiform signs for Sumerian as well as for their own language.
The contents of the earliest clay tablets are simple notations of numbers of commodities—animals, jars, baskets, etc. Writing, it would appear, started as a primitive form of bookkeeping. Its use soon widened to document the multitudinous things and acts that are involved in daily life, from simple inventories of commodities to complicated governmental rules and regulations.
Archaeologists frequently find clay tablets in batches. The batches, some of which contain thousands of tablets, consist for the most part of documents of the types just mentioned: bills, deliveries, receipts, inventories, loans, marriage contracts, divorce settlements, court judgments, and so on. These records of factual matters were kept in storage to be available for reference-they were, in effect, files, or, to use the term preferred by specialists in the ancient Near East, archives. Now and then these files include pieces of writing that are of a distinctly different order, writings that do not merely record some matter of fact but involve creative intellectual activity. They range from simple textbook material to literature-and they make an appearance very early, even from the third millennium B.C.E.
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The Commercial Revolution in Medieval EuropeBeginning in the 1160s, the opening of new silver mines in northern Europe led to the minting and circulation of vast quantities of silver coins. The widespread use of cash greatly increased the volume of international trade. Business procedures changed radically. The individual traveling merchant who alone handled virtually all aspects of exchange evolved into an operation involving three separate types of merchants: the sedentary merchant who ran the "home office," financing and organizing the firm’s entire export-import trade; the carriers who transported goods by land and sea; and the company agents resident in cities abroad who, on the advice of the home office, looked after sales and procurements.
Commercial correspondence, unnecessary when one businessperson oversaw everything and made direct bargains with buyers and sellers, multiplied. Regular courier service among commercial cities began. Commercial accounting became more complex when firms had to deal with shareholders, manufacturers, customers, branch offices, employees, and competing firms. Tolls on roads became high enough to finance what has been called a road revolution, involving new surfaces and bridges, new passes through the Alps, and new inns and hospices for travelers. The growth of mutual trust among merchants facilitated the growth of sales on credit and led to new developments in finance, such as the bill of exchange, a device that made the long, slow, and very dangerous shipment of coins unnecessary.
The ventures of the German Hanseatic League illustrate these advancements. The Hanseatic League was a mercantile association of European towns dating from 1159. The league grew by the end of the fourteenth century to include about 200 cities from Holland to Poland. Across regular, well- defined trade routes along the Baltic and North seas, the ships of league cities carried furs, wax, copper, fish, grain, timber, and wine. These goods were exchanged for finished products, mainly cloth and salt, from western cities. At cities such as Bruges and London, Hanseatic merchants secured special trading concessions, exempting them from all tolls and allowing them to trade at local fairs. Hanseatic merchants established foreign trading centers, the most famous of which was the London Steelyard, a walled community with warehouses, offices, a church, and residential quarters for company representatives. By the late thirteenth century, Hanseatic merchants had developed an important business technique, the business register. Merchants publicly recorded their debts and contracts and received a league guarantee for them. This device proved a decisive factor in the later development of credit and commerce in northern Europe.
These developments added up to what one modern scholar has called "a commercial revolution." In the long run, the commercial revolution of the High Middle Ages (A D 1000-1300) brought about radical change in European society. One remarkable aspect of this change was that the commercial classes constituted a small part of the total population—never more than 10 percent. They exercised an influence far in excess of their numbers. The commercial revolution created a great deal of new wealth, which meant a higher standard of living. The existence of wealth did not escape the attention of kings and other rulers. Wealth could be taxed, and through taxation, kings could create strong and centralized states. In the years to come, alliances with the middle classes were to enable kings to weaken aristocratic interests and build the states that came to be called modern.
The commercial revolution also provided the opportunity for thousands of agricultural workers to improve their social position. The slow but steady transformation of European society from almost completely rural and isolated to relatively more urban constituted the greatest effect of the commercial revolution that began in the eleventh century. Even so, merchants and business people did not run medieval communities, except in central and northern Italy and in the county of Flanders. Most towns remained small. The nobility and churchmen determined the predominant social attitudes, values, and patterns of thought and behavior. The commercial changes of the eleventh through fourteenth centuries did, however, lay the economic foundation for the development of urban life and culture.
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Ecosystem Diversity and StabilityConservation biologists have long been concerned that species extinction could have significant consequences for the stability of entire ecosystems—groups of interacting organisms and the physical environment that they inhabit. An ecosystem could survive the loss of some species, but if enough species were lost, the ecosystem would be severely degraded. In fact, it is possible that the loss of a single important species could start a cascade of extinctions that might dramatically change an entire ecosystem. A good illustration of this occurred after sea otters were eliminated from some Pacific kelp (seaweed) bed ecosystems: the kelp beds were practically obliterated too because in the absence of sea otter predation, sea urchin populations exploded and consumed most of the kelp and other macroalgae.
It is usually claimed that species-rich ecosystems tend to be more stable than species-poor ecosystems. Three mechanisms by which higher diversity increases ecosystem stability have been proposed. First, if there are more species in an ecosystem, then its food web will be more complex, with greater redundancy among species in terms of their nutritional roles. In other words, in a rich system if a species is lost, there is a good chance that other species will take over its function as prey, predator, producer, decomposer, or whatever role it played. Second, diverse ecosystems may be less likely to be invaded by new species, notably exotics (foreign species living outside their native range), that would disrupt the ecosystem’s structure and function. Third, in a species-rich ecosystem, diseases may spread more slowly because most species will be relatively less abundant, thus increasing the average distance between individuals of the same species and hampering disease transmission among individuals.
Scientific evidence to illuminate these ideas has been slow in coming, and many shadows remain. One of the first studies to provide data supporting a relationship between diversity and stability examined how grassland plants responded to a drought. Researchers D. Tilman and J A. Downing used the ratio of above-ground biomass in 1988 (after two years of drought) to that in 1986 (predrought) in 207 plots in a grassland field in the Cedar Creek Natural History Area in Minnesota as an index of ecosystem response to disruption by drought. In an experiment that began in 1982, they compared these values with the number of plant species in each plot and discovered that the plots with a greater number of plant species experienced a less dramatic reduction in biomass. Plots with more than ten species had about half as much biomass in 1988 as in 1986, whereas those with fewer than five species only produced roughly one-eighth as much biomass after the two-year drought. Apparently, species-rich plots were likely to contain some drought-resistant plant species that grew better in drought years, compensating for the poor growth of less-tolerant species.
To put this result in more general terms, a species-rich ecosystem may be more stable because it is more likely to have species with a wide array of responses to variable conditions such as droughts. Furthermore, a species-rich ecosystem is more likely to have species with similar ecological functions, so that if a species is lost from an ecosystem, another species, probably a competitor, is likely to flourish and occupy its functional role. Both of these, variability in responses and functional redundancy, could be thought of as insurance against disturbances.
The Minnesota grassland research has been widely accepted as strong evidence for the diversity- stability theory; however, its findings have been questioned, and similar studies on other ecosystems have not always found a positive relationship between diversity and stability. Clearly, this is a complex issue that requires further field research with a broad spectrum of ecosystems and species: grassland plants and computer models will only take us so far. In the end, despite insightful attempts to detect some general patterns, we may find it very difficult to reduce this topic to a simple, universal truth.
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Roman Cultural Influence on BritainAfter the Roman Empire's conquest of Britain in the first century A.D., the presence of administrators, merchants, and troops on British soil, along with the natural flow of ideas and goods from the rest of the empire, had an enormous influence on life in the British Isles. Cultural influences were of three types: the bringing of objects, the transfer of craft workers, and the introduction of massive civil architecture. Many objects were not art in even the broadest sense and comprised utilitarian items of clothing, utensils, and equipment. We should not underestimate the social status associated with such mundane possessions which had not previously been available. The flooding of Britain with red-gloss pottery from Gaul (modern-day France), decorated with scenes from Classical mythology, probably brought many into contact with the styles and artistic concepts of the Greco-Roman world for the first time, whether or not the symbolism was understood. Mass-produced goods were accompanied by fewer more aesthetically impressive objects such as statuettes. Such pieces perhaps first came with officials for their own religious worship; others were then acquired by native leaders as diplomatic gifts or by purchase. Once seen by the natives, such objects created a fashion which rapidly spread through the province.
In the most extreme instances, natives literally bought the whole package of Roman culture. The Fishbourne villa, built in the third quarter of the first century A.D., probably for the native client king Cogidubnus, amply illustrates his Roman pretensions. It was constructed in the latest Italian style with imported marbles and stylish mosaics. It was lavishly furnished with imported sculptures and other Classical objects. A visitor from Rome would have recognized its owner as a participant in the contemporary culture of the empire, not at all provincial in taste. Even if those from the traditional families looked down on him, they would have been unable to dismiss him as uncultured. Although exceptional, this demonstrates how new cultural symbols bound provincials to the identity of the Roman world.
Such examples established a standard to be copied. One result was an influx of craft worker, particularly those skilled in artistic media like stone-carving which had not existed before the conquest. Civilian workers came mostly from Gaul and Germany. The magnificent temple built beside the sacred spring at Bath was constructed only about twenty years after the conquest. Its detail shows that it was carved by artists from northeast Gaul. In the absence of a tradition of Classical stone-carving and building, the desire to develop Roman amenities would have been difficult to fulfill. Administrators thus used their personal contacts to put the Britons in touch with architects and masons. As many of the officials in Britain had strong links with Gaul, it is not surprising that early Roman Britain owes much to craft workers from that area. Local workshops did develop and stylistically similar groups of sculpture show how skills in this new medium became widerspread. Likewise skills in the use of mosaic, wall painting, ceramic decoration, and metal-working developed throughout the province with the eventual emergence of characteristically Romano-British styles.
This art had a major impact on the native peoples, and one of the most important factors was a change in the scale of buildings. Pre-Roman Britain was highly localized, with people rarely traveling beyond their own region. On occasion large groups amassed for war or religious festivals, but society remained centered on small communities. Architecture of this era reflected this with even the largest of the fortified towns and hill forts containing no more than clusters of medium-sized structures. The spaces inside even the largest roundhouses were modest, and the use of rounded shapes and organic building materials gave buildings a human scale. But the effect of Roman civil architecture was significant. The sheer size of space enclosed within buildings like the basilica of London must have been astonishing. This was an architecture of dominance in which subject peoples were literally made to feel small by buildings that epitomized imperial power. Supremacy was accentuated by the unyielding straight lines of both individual buildings and planned settlements since these too provided a marked contrast with the natural curvilinear shapes dominant in the native realm.
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Termite IngenuityTermites, social insects which live in colonies that, in some species, contain 2 million individuals or more, are often incorrectly referred to as white ants. But they are certainly not ants. Termites, unlike ants, have gradual metarnorphosis with only three life stage: egg, nymph, and adult. Ants and the other social members of their order, certain bees and wasps, have complete metarnorphosis in four life stages; egg, larva, pupa, and adult. The worker and soldier castes of social ants, bees, and wasps consist of only females, all daughters of a single queen that mated soon after she matured and thereafter never mated again. The worker and soldier castes of termites consist of both males and females, and the queen lives permanently with a male consort.
Since termites are small and soft-bodied, they easily become desiccated and must live in moist places with a high relative humidity. They do best when the relative humidity in their nest is above 96 percent and the temperature is fairly high, an optimum of about 79°F for temperate zone species and about 86°F for tropical species. Subterranean termites, the destructive species that occurs commonly throughout the eastern United States, attain these conditions by nesting in moist soil that is in contact with wood, their only food. The surrounding soil keeps the nest moist and tends to keep the temperature at a more or less favorable level. When it is cold in winter, subterranean termites move to burrows below the frost line.
Some tropical termites are more ingenious engineers, constructing huge above-ground nests with built-in "air conditioning" that keeps the nest moist, at a constant temperature, and well supplied with oxygen. Among the most architecturally advanced of these termites is an African species, Macroternes natalensis. Renowned Swiss entomologist Martin Luscher described the mounds of this fungus-growing species as being as much as 16 feet tall, 16 feet in diameter at their base, and with a cement-like wall of soil mixed with termite saliva that is from 16 to 23 inches thick. The thick and dense wall of the mound insulates the interior microclimate from the variations in humidity and temperature of the outside atmosphere. Several narrow and relatively thin-walled ridges on the outside of the mound extend from near its base almost to its top.
According to Luscher, a medium-sized nest of Macrotermes has a population of about 2 million individuals. The metabolism of so many termites and of the fungus that they grow in their gardens as food helps keep the interior of the nest warm and supplies some moisture to the air in the nest. The termites saturate the atmosphere of the nest, bringing it to about 100 percent relative humidity, by carrying water up from the soil.
But how is this well-insulated nest ventilated? Its many occupants require over 250 quarts of oxygen (more than 1,200 quarts of air ) per day. How can so much oxygen diffuse through the thick walls of the mound? Even the pores in the wall are filled with water, which almost stops the diffusion of gases. The answer lies in the construction of the nest. The interior consists of a large central core in which the fungus is grown, below it is "cellar" of empty space, above it is an "attic" of empty space, and within the ridges on the outer wall of the nest, there are many small tunnels that connect the cellar and the attic. The warm air in the fungus gardens rises through the nest up to the attic. From the attic, the air passes into the tunnels in the ridges and flows back down to the cellar. Gases, mainly oxygen coming in and carbon dioxide going out, easily diffuse into or out of the ridges, since their walls are thin and their surface area is large because they protrude far out from the wall of the mound. Thus air that flows down into the cellar through the ridges is relatively rich in oxygen, and has lost much of its carbon dioxide. It supplies the nest’s inhabitants with fresh oxygen as it rises through the fungus-growing area back up to the attic.
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Coral ReefsAn important environment that is more or less totally restricted to the intertropical zone is the coral reef. Coral reefs are found where the ocean water temperature is not less than 21 °C, where there is a firm substratum, and where the seawater is not rendered too dark by excessive amounts of river-borne sediment. They will not grow in very deep water, so a platform within 30 to 40 meters of the surface is a necessary prerequisite for their development. Their physical structure is dominated by the skeletons of corals, which are carnivorous animals living off zooplankton. However, in addition to corals there are enormous quantities of algae, some calcareous, which help to build the reefs. The size of reefs is variable. Some atolls are very large—Kwajelein in the Marshall Islands of the South Pacific is 120 kilometers long and as much as 24 kilometers across-but most are very much smaller, and rise only a few meters above the water. The 2,000 kilometer complex of reefs known as the Great Barrier Reef, which forms a gigantic natural breakwater off the northeast coast of Australia, is by far the greatest coral structure on Earth.
Coral reefs have fascinated scientists for almost 200 years, and some of the most pertinent observations of them were made in the 1830s by Charles Darwin on the voyage of the Beagle. He recognized that there were three major kinds: fringing reefs, barrier reefs, and atolls; and he saw that they were related to each other in a logical and gradational sequence. A fringing reef is one that lies close to the shore of some continent or island. Its surface forms an uneven and rather rough platform around the coast, about the level of low water, and its outer edge slopes downwards into the sea. Between the fringing reef and the land there is sometimes a small channel or lagoon. When the lagoon is wide and deep and the reef lies at some distance from the shore and rises from deep water it is called a barrier reef. An atoll is a reef in the form of a ring or horseshoe with a lagoon in the center.
Darwin s theory was that the succession from one coral reef type to another could be achieved by the upward growth of coral from a sinking platform, and that there would be a progression from a fringing reef, through the barrier reef stage until, with the disappearance through subsidence (sinking) of the central island, only a reef-enclosed lagoon or atoll would survive. A long time after Darwin put forward this theory, some deep boreholes were drilled in the Pacific atolls in the 1950s. The drill holes passed through more than a thousand meters of coral before reaching the rock substratum of the ocean floor, and indicated that the coral had been growing upward for tens of millions of years as Earth's crust subsided at a rate of between 15 and 51 meters per million years. Darwin s theory was therefore proved basically correct. There are some submarine islands called guyots and seamounts, in which subsidence associated with sea-floor spreading has been too speedy for coral growth to keep up.
Like mangrove swamps, coral reefs are extremely important habitats. Their diversity of coral genera is greatest in the warm waters of the Indian Ocean and the western Pacific. Indeed, they have been called the marine version of the tropical rain forest, rivaling their terrestrial counterparts in both richness of species and biological productivity. They also have significance because they provide coastal protection, opportunities for recreation, and are potential sources of substances like medicinal drugs. At present they are coming under a variety of threats, of which two of the most important are dredging and the effects of increased siltation brought about by accelerated erosion from neighboring land areas.
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Chinese Population GrowthIncreases in population have usually been accompanied (indeed facilitated) by an increase in trade. In the Western experience, commerce provided the conditions that allowed industrialization to get started, which in turn led to growth in science, technology, industry, transport, communications, social change, and the like that we group under the broad term of "development". However, the massive increase in population that in Europe was at first attributed to industrialization starting in the eighteenth century occurred also and at the same period in China, even though there was no comparable industrialization.
It is estimated that the Chinese population by 1600 was close to 150 million. The transition between the Ming and Qing dynasties (the seventeenth century) may have seen a decline, but from 1741 to 1851 the annual figures rose steadily and spectacularly, perhaps beginning with 143 million and ending with 432 million. If we accept these totals, we are confronted with a situation in which the Chinese population doubled in the 50 years from 1790 to 1840. If, with greater caution, we assume lower totals in the early eighteenth century and only 400 million in 1850, we still face a startling fact: something like a doubling of the vast Chinese population in the century before Western contact, foreign trade, and industrialization could have had much effect.
To explain this sudden increase we cannot point to factors constant in Chinese society but must find conditions or a combination of factors that were newly effective in this period. Among these is the almost complete internal peace maintained under Manchu rule during the eighteenth century. There was also an increase in foreign trade through Guangzhou (southern China) and some improvement of transportation within the empire. Control of disease, like the checking of smallpox by variolation may have been important. But of most critical importance was the food supply.
Confronted with a multitude of unreliable figures, economists have compared the population records with the aggregate data for cultivated land area and grain production in the six centuries since 1368. Assuming that China's population in 1400 was about 80 million, the economist Dwight Perkins concludes that its growth to 700 million or more in the 1960s was made possible by a steady increase in the grain supply, which evidently grew five or six times between 1400 and 1800 and rose another 50 percent between 1800 and 1965. This increase of food supply was due perhaps half to the increase of cultivated area, particularly by migration and settlement in the central and western provinces, and half to greater productivity—the farmers' success in raising more crops per unit of land.
This technological advance took many forms: one was the continual introduction from the south of earlier-ripening varieties of rice, which made possible double-cropping (the production of two harvests per year from one field). New crops such as corn (maize) and sweet potatoes as well as peanuts and tobacco were introduced from the Americas. Corn, for instance, can be grown on the dry soil and marginal hill land of North China, where it is used for food, fuel, and fodder and provides something like one-seventh of the food energy available in the area. The sweet potato, growing in sandy soil and providing more food energy per unit of land than other crops, became the main food of the poor in much of the South China rice area.
Productivity in agriculture was also improved by capital investments, first of all in irrigation. From 1400 to 1900 the total of irrigated land seems to have increased almost three times. There was also a gain in farm tools, draft animals, and fertilizer, to say nothing of the population growth itself, which increased half again as fast as cultivated land area and so increased the ratio of human hands available per unit of land. Thus the rising population was fed by a more intensive agriculture, applying more labor and fertilizer to the land.
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Determining Dinosaur DietDetermining what extinct dinosaurs ate is difficult, but we can infer some aspects of their dietary preferences. Traditionally, this information has been derived from direct evidence, such as stomach contents, and indirect evidence, such as establishing a correlation between particular body characteristics and diets of living animals and then inferring habits for dinosaurs.
Animals such as house cats and dogs have large, stabbing canine teeth at the front of the mouth and smaller, equally sharp teeth farther back in their jaws. Many of these animals are also armed with sharp claws. The advantage of teeth and claws as predatory tools is obvious. Now consider animals like cows, horses, rabbits, and mice. These animals have flat teeth at the back of the jaw that are analogous to and have the same function as grindstones. Unlike the meat-slicing and stabbing teeth of carnivores, the teeth of these animals grind and shred plant material before digestion.
More clues exist in other parts of the skull. The jaw joint of carnivores such as dogs and cats has the mechanical advantage of being at the same level as the tooth row, allowing the jaws to close with tremendous speed and forcing the upper teeth to occlude against the lower teeth with great precision. In herbivorous animals, rapid jaw closure is less important. Because the flat teeth of herbivores work like grindstones, however, the jaws must move both side to side and front to back. The jaw joints of many advanced herbivores, such as cows, lie at a different level than the tooth row, allowing transverse tearing, shredding, and compression of plant material. If we extend such observations to extinct dinosaurs, we can infer dietary preferences (such as carnivory and herbivory), even though we cannot determine the exact diet. The duck-billed dinosaurs known as hadrosaurs are a good example of a group whose jaw joint is below the level of the tooth row, which probably helped them grind up tough, fibrous vegetation.
Paleontologists would like to be much more specific about a dinosaur's diet than simply differentiating carnivore from herbivore. This finer level of resolution requires direct fossil evidence of dinosaur meals. Stomach contents are only rarely preserved, but when present, allow us to determine exactly what these animals were eating.
In the stomach contents of specimens of Coelophysis (a small, long-necked dinosaur) are bones from juvenile animals of the same species. At one time, these were thought to represent embryonic animals, suggesting that this small dinosaur gave birth to live young rather than laying eggs. Further research indicated that the small dinosaurs were too large and too well developed to be prehatchling young. In addition, the juveniles inside the body cavity were of different sizes. All the evidence points to the conclusion that these are the remains of prey items and that, as an adult, Coelophysis was at least in part a cannibal.
Fossilized stomach contents are not restricted to carnivorous dinosaurs. In a few rare cases, most of them "mummies" (unusually well preserved specimens), fossilized plant remains have been found inside the body cavity of hadrosaurs. Some paleontologists have argued that these represent stream accumulations rather than final meals. The best known of these cases is the second Edmontosaurus mummy collected by the Sternbergs. In the chest cavity of this specimen, which is housed in the Senckenberg Museum in Germany, are the fossil remains of conifer needles, twigs, seeds, and fruits. Similar finds in Corythosaurus specimens from Alberta, Canada, have also been reported, indicating that at least two kinds of Late Cretaceous hadrosaurs fed on the sorts of tress that are common in today's boreal woodlands.
A second form of direct evidence comes from coprolites (fossilized bodily waste). Several dinosaur fossil localities preserve coprolites. Coprolites yield unequivocal evidence about the dietary habits of dinosaurs. Many parts of plants and animals are extremely resistant to the digestive systems of animals and pass completely through the body with little or no alteration. Study of coprolites has indicated that the diets of some herbivorous dinosaurs were relatively diverse, while other dinosaurs appear to have been specialists, feeding on particular types of plants. The problem with inferring diets from coprolites is the difficulty in accurately associating a particular coprolite with a specific dinosaur.
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"Climate and Urban DevelopmentFor more than a hundred years, it has been known that cities are generally warmer than surrounding rural areas. This region of city warmth, known as the urban heat island, can influence the concentration of air pollution. However, before we look at its influence, let's see how the heat island actually forms.
The urban heat island is due to industrial and urban development. In rural areas, a large part of the incoming solar energy is used in evaporating water from vegetation and soil. In cities, where less vegetation and exposed soil exist, the majority of the Sun's energy is absorbed by urban structures and asphalt. Hence, during warm daylight hours, less evaporative cooling in cities allows surface temperatures to rise higher than in rural areas. The cause of the urban heat island is quite involved. Depending on the location, time of year, and time of day, any or all of the following differences between cities and their surroundings can be important: albedo (reflectivity of the surface), surface roughness, emissions of heat, emissions of moisture, and emissions of particles that affect net radiation and the growth of cloud droplets.
At night, the solar energy (stored as vast quantities of heat in city buildings and roads) is slowly released into the city air. Additional city heat is given off at night (and during the day) by vehicles and factories, as well as by industrial and domestic heating and cooling units. The release of heat energy is retarded by the tall vertical city walls that do not allow infrared radiation to escape as readily as does the relatively level surface of the surrounding countryside. The slow release of heat tends to keep nighttime city temperatures higher than those of the faster-cooling rural areas. Overall, the heat island is strongest at night when compensating sunlight is absent; during the winter, when nights are longer and there is more heat generated in the city; and when the region is dominated by a high-pressure area with light winds, clear skies, and less humid air. Over time, increasing urban heat islands affect climatological temperature records, producing artificial warming in climatic records taken in cities. This warming, therefore, must be accounted for in interpreting climate change over the past century.
The constant outpouring of pollutants into the environment may influence the climate of the city. Certain particles reflect solar radiation, thereby reducing the sunlight that reaches the surface. Some particles serve as nuclei upon which water and ice form. Water vapor condenses onto these particles when the relative humidity is as low as 70 percent, forming haze that greatly reduces visibility. Moreover, the added nuclei increase the frequency of city fog.
Studies suggest that precipitation may be greater in cities than in the surrounding countryside; this phenomenon may be due in part to the increased roughness of city terrain, brought on by large structures that cause surface air to slow and gradually converge. This piling up of air over the city then slowly rises, much like toothpaste does when its tube is squeezed. At the same time, city heat warms the surface air, making it more unstable, which enhances risings air motions, which, in turn, aids in forming clouds and thunderstorms. This process helps explain why both tend to be more frequent over cities.
On clear still nights when the heat island is pronounced, a small thermal low-pressure area forms over the city. Sometimes a light breeze—called a country breeze—blows from the countryside into the city. If there are major industrial areas along the outskirts, pollutants are carried into the heat of town, where they tend to concentrate. Such an event is especially probable if vertical mixing and dispersion of pollutants are inhibited. Pollutants from urban areas may even affect the weather downwind from them. "
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Ancient CoastlinesInformation on past climates is of primary relevance to archaeology because of what it tells us about the effects on the land and on the resources that people needed to survive.The most crucial effect of climate was on the sheer quantity of land available in each period,measurable by studying ancient coastlines.These have changed constantly through time,even in relatively recent periods,as can be seen from the Neolithic stone circle of Er Lannic,in Brittany,France(once inland but now half submerged on an island)or medieval villages in east Yorkshire,England,that have tumbled into the sea in the last few centuries as the North Sea gnaws its way westward and erodes the cliffs.Conversely,silts deposited by rivers sometimes push the sea farther back,creating new land,as at Ephesus in western Turkey,a port on the coast in Roman times but today some five kilometers inland.
Nevertheless,for archeologists concerned with the long periods of time of the Paleolithic period there are variations in coastlines of much greater magnitude to consider.The expansion and contraction of the continental glaciers caused huge and uneven rises and falls in sea levels worldwide.When the ice sheets grew,the sea level would drop as water became locked up in the glaciers;when the ice melted,the sea level would rise again.Falls in sea level often exposed a number of important land bridges,such as those linking Alaska to northeast Asia and Britain to northwest Europe,a phenomenon with far-reaching effects not only on human colonization of the globe but also on the environment as a whole-the flora and fauna of isolated or insular areas were radically and often irreversibly affected.Between Alaska and Asia today lies the Bering Strait,which is so shallow that a fall in sea level of only four meters would turn it into a land bridge.When the ice sheets were at their greatest extent some 18,000 years ago (the glacier maximum),it is thought that the fall was about 120 meters,which therefore created not merely a bridge but a vast plain,1,000 kilometers from the north to the south,which has been called Beringia.The existence of Beringia(and the extent to which it could have supported human life)is one of the crucial pieces of evidence in the continuing debate about the likely route and date of human colonization of the New World.
The assessment of past rises and falls in sea level requires study of submerged land surfaces off the coast and of raised or elevated beaches on land.Raised beaches are remnants of former coastlines at higher levels relative to the present shoreline and visible,for instance,along the Californian coast north of San Francisco.The height of a raised beach above the present shoreline,however,does not generally give a straightforward indication of the height of a former sea level.In the majority of cases,the beaches lie at a higher level because the land has been raised up through isostatic uplift or tectonic movement.Isostatic uplift of the land occurs when the weight of ice is removed as temperatures rise,as at the end of an ice age;it has affected coastlines,for example,in Scandinavia,Scotland,Alaska,and Newfoundland during the postglacial period.Tectonic movements involve displacements in the plates that make up Earth’s crust.Middle and Late Pleistocene raised beaches in the Mediterranean are one instance of such movements.
Raised beaches often consist of areas of sand,pebbles,or dunes,sometimes containing seashells or piles of debris comprising shells and bones of marine animals used by humans.In Tokyo Bay,for example,shell mounds of the Jomon period(about 10,000 to 300 B.C.E.)mark the position of the shoreline at a time of maximum inundation by the sea(6,500-5,500 years ago),when, through tectonic movement,the sea was three to five meters higher in relation to the contemporary landmass of Japan than at present.Analysis of the shells themselves has confirmed the changes in marine topography,for it is only during the maximum phase that subtropical species of mollusc are present,indicating a higher water temperature.
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Movable TypeNothing divided the medieval world in Europe more decisively from the Early Modern period than printing with movable type. It was a German invention and the culmination of a complex process. The world of antiquity had recorded its writings mainly on papyrus. Between 200 B.C and A.D 300, this was supplemented by vellum, calf skin treated and then smoothed by pumice stone. To this in late Roman times was added parchment, similarly made from the smoothed skin of sheep or goats. In the early Middle Ages, Europe imported an industrial process from China, which turned almost any kind of fibrous material into pulp that was then spread in sheets. This was known as cloth parchment. By about 1150 the Spanish had developed the first mill for making cheap paper (a word contracted from "papyrus", which became the standard term). One of the most important phenomena of the later Middle Ages was the growing availability of cheap paper. Even in England, where technology lagged far behind, a sheet of paper, or eight octavo pages, cost only a penny by the fifteenth century.
In the years 1446-1448, two German goldsmiths, Johannes Gutenberg and Johann Fust, made use of cheap paper to introduce a critical improvement in the way written pages were reproduced. Printing from wooden blocks was the old method; what the Germans did was to invent movable type for the letterpress. It had three merits: it could be used repeatedly until worn out; it was cast in metal from a mold and so could be renewed without difficulty; and it made lettering uniform. In 1450, Gutenberg began work on his Bible, the first printed book, known as the Gutenberg. It was completed in 1455 and is a marvel. As Gutenberg, apart from getting the key idea, had to solve a lot of practical problems, including imposing paper and ink into the process and the actual printing itself, for which he adapted the screw press used by winemakers, it is amazing that his first product does not look at all rudimentary. Those who handle it are struck by its clarity and quality.
Printing was one of those technical revolutions that developed its own momentum at extraordinary speed. Europe in the fifteenth century was a place where intermediate technology-that is, workshops with skilled craftspeople-was well established and spreading fast, especially in Germany and Italy. Such workshops were able to take on printing easily, and it thus became Europe's first true industry. The process was aided by two factors: the new demand for cheap classical texts and the translation of the Latin Bible into "modern" languages. Works of reference were also in demand. Presses sprang up in several German cities, and by 1470, Nuremberg, Germany had established itself as the center of the international publishing trade, printing books from 24 presses and distributing them at trade fairs all over western and central Europe. The old monastic scriptoria-monastery workshops where monks copied texts by hand-worked closely alongside the new presses, continuing to produce the luxury goods that movable-type printing could not yet supply. Printing, however, was primarily aimed at a cheap mass sale.
Although there was no competition between the technologies, there was rivalry between nations. The Italians made energetic and successful efforts to catch up with Germany. Their most successful scriptorium quickly imported two leading German printers to set up presses in their book-producing shop.German printers had the disadvantage of working with the complex typeface that the Italians sneeringly referred to as "Gothic" and that later became known as black letter. Outside Germany, readers found this typeface disagreeable. The Italians, on the other hand, had a clear typeface known as roman that became the type of the future.
Hence, although the Germans made use of the paper revolution to introduce movable type, the Italians went far to regain the initiative by their artistry. By 1500 there were printing firms in 60 German cities, but there were 150 presses in Venice alone. However, since many nations and governments wanted their own presses, the trade quickly became international. The cumulative impact of this industrial spread was spectacular. Before printing, only the very largest libraries, of which there were a dozen in Europe, had as many as 600 books. The total number of books on the entire Continent was well under 100,000. But by 1500, after only 45 years of the printed book, there were 9 million in circulation.
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Background for the Industrial RevolutionThe Industrial Revolution had several roots, one of which was a commercial revolution that, beginning as far back as the sixteenth century, accompanied Europe’s expansion overseas. Both exports and imports showed spectacular growth, particularly in England and France. An increasingly larger portion of the stepped-up commercial activity was the result of trade with overseas colonies. Imports included a variety of new beverages, spices, and ship’s goods around the world and brought money flowing back. Europe’s economic institutions, particularly those in England, were strong, had wealth available for new investment, and seemed almost to be waiting for some technological breakthrough that would expand their profit-making potential even more.
The breakthrough came in Great Britain, where several economic advantages created a climate especially favorable to the encouragement of new technology. One was its geographic location at the crossroads of international trade. Internally, Britain was endowed with easily navigable natural waterway, which helped its trade and communication with the world. Beginning in the 1770’s, it enjoyed a boom in canal building, which helped make its domestic market more accessible. Because water transportation was the cheapest means of carrying goods to market, canals reduced prices and thus increased consumer demand. Great Britain also had rich deposits of coal that fed the factories springing up in industrial and consumer goods.
Another advantage was Britain’s large population of rural, agricultural wage earners,as well as cottage workers, who had the potential of being more mobile than peasants of some other countries. Eventually they found their way to the cities or mining communities and provided the human power upon which the Industrial Revolution was built. The British people were also consumers; the absence of internal tariffs, such as those that existed in France or Italy or between the German states, made Britain the largest free-trade area in Europe. Britain’s relatively stable government also helped create an atmosphere conducive to industrial progress.
Great Britain’s better-developed banking and credit system also helped speed the industrial progress, as did the fact that it was the home of an impressive array of entrepreneurs and inventors. Among them were a large number of nonconformists whose religious principles encouraged thrift and industry rather than luxurious living and who tended to pour their profits back into their business, thus providing the basis for continued expansion.
A precursor to the Industrial Revolution was a revolution in agricultural techniques. Ideas about agricultural reform developed first in Holland, where as early as the mid-seventeenth century, such modern methods as crop rotation, heavy fertilization, and diversification were all in use. Dutch peasant farmers were known throughout Europe for their agricultural innovations, but as British markets and opportunities grew, the English quickly learned from them. As early as the seventeenth century the Dutch were helping them drain marshes and fens where, with the help of advanced techniques, they grew new crops. By the mid-eighteenth century new agricultural methods as well as selective breeding of livestock had caught on throughout the country.
Much of the increased production was consumed by Great Britain’s burgeoning population. At the same time, people were moving to the city, partly because of the enclosure movement; that is, the fencing of common fields and pastures in order to provide more compact, efficient privately held agricultural parcels that would produce more goods and greater profits. In the sixteenth century enclosures were usually used for creating sheep pastures, but by the eighteenth century new farming techniques made it advantageous for large landowners to seek enclosures in order to improve agricultural production. Between 1714 and 1820 over 6 million acres of English land were enclosed. As a result, many small, independent farmers were forced to sell out simply because they could not compete. Non-landholding peasants and cottage workers, who worked for wages and grazed cows or pigs on the village common, were also hurt when the common was no longer available. It was such people who began to flock to the cities seeking employment and who found work in the factories that would transform the nation and, the world.
R50P1
"American RailroadsIn the United States, railroads spearheaded the second phase of the transportation revolution by overtaking the previous importance of canals. The mid-1800s saw a great expansion of American railroads. The major cities east of the Mississippi River were linked by a spiderweb of railroad tracks. Chicago's growth illustrates the impact of these rail links. In 1849 Chicago was a village of a few hundred people with virtually no rail service. By 1860 it had become a city of 100,000, served by eleven railroads.Farmers to the north and west of Chicago no longer had to ship their grain, livestock, and dairy products down the Mississippi River to New Orleans; they could now ship their products directly east. Chicago supplanted New Orleans as the interior of America's main commercial hub.
The east-west rail lines stimulated the settlement and agricultural development of the Midwest. By 1860 Illinois, Indiana, and Wisconsin had replaced Ohio, Pennsylvania, and New York as the leading wheat-growing states. Enabling farmers to speed their products to the East, railroads increased the value of farmland and promoted additional settlement. In turn, population growth in agricultural areas triggered industrial development in cities such as Chicago, Davenport (Iowa), and Minneapolis, for the new settlers needed lumber for fences and houses and mills to grind wheat into flour.
Railroads also propelled the growth of small towns along their routes. The Illinois Central Railroad, which had more track than any other railroad in 1855, made money not only from its traffic but also from real estate speculation. Purchasing land for stations along its path, the Illinois Central then laid out towns around the stations. The selection of Manteno, Illinois, as a stop of the Illinois Central, for example, transformed the site from a crossroads without a single house in 1854 into a bustling town of nearly a thousand in 1860, replete with hotels, lumberyards, grain elevators, and gristmills. By the Civil War (1861-1865), few thought of the railroad-linked Midwest as a frontier region or viewed its inhabitants as pioneers.
As the nation's first big business, the railroads transformed the conduct of business. During the early 1830s, railroads, like canals, depended on financial aid from state governments. With the onset of economic depression in the late 1830s, however, state governments scrapped overly ambitious railroad projects. Convinced that railroads burdened them with high taxes and blasted hopes, voters turned against state aid, and in the early 1840s, several states amended their constitutions to bar state funding for railroads and canals. The federal government took up some of the slack, but federal aid did not provide a major stimulus to railroads before 1860. Rather, part of the burden of finance passed to city and county governments in agricultural areas that wanted to attract railroads. Such municipal governments, for example, often gave railroads rights-of-way, grants of land for stations, and public funds.
The dramatic expansion of the railroad network in the 1850s, however, strained the financing capacity of local governments and required a turn toward private investment, which had never been absent from the picture. Well aware of the economic benefits of railroads, individuals living near them had long purchased railroad stock issued by governments and had directly bought stock in railroads, often paying by contributing their labor to building the railroads. But the large railroads of the 1850s needed more capital than such small investors could generate. Gradually, the center of railroad financing shifted to New York City, and in fact, it was the railroad boom of the 1850s that helped make Wall Street in New York City the nation's greatest capital market. The stocks of all the leading railroads were traded on the floor of the New York Stock Exchange during the 1850s. In addition, the growth of railroads turned New York City into the center of modern investment firms. The investment firms evaluated the stock of railroads in the smaller American cities and then found purchasers for these stocks in New York City, Philadelphia, Paris, London, Amsterdam, and Hamburg. Controlling the flow of funds to railroads, the investment bankers began to exert influence over the railroads' internal affairs by supervising administrative reorganizations in times of trouble. "
R50P2
"The Achievement of Brazilian IndependenceIn contrast to the political anarchy, economic dislocation, and military destruction in Spanish America, Brazil's drive toward independence from Portugal proceeded as a relatively bloodless transition between 1808 and 1822. The idea of Brazilian independence first arose in the late eighteenth century as a Brazilian reaction to the Portuguese policy of tightening political and economic control over the colony in the interests of the mother country. The first significant conspiracy against Portuguese rule was organized from 1788-1799 in the province of Minas Gerais, where rigid governmental control over the production and prices of gold and diamonds, as well as heavy taxes, caused much discontent. But this conspiracy never went beyond the stage of discussion and was easily discovered and crushed. Other conspiracies in the late eighteenth century as well as a brief revolt in 1817 reflected the influence of republican ideas over sections of the elite and even the lower strata of urban society. All proved abortive or were soon crushed. Were it not for an accident of European history, the independence of Brazil might have been long delayed.
The French invasion of Portugal in 1807 followed by the flight of the Portuguese court (sovereign and government officers) to Rio de Janeiro brought large benefits to Brazil. Indeed, the transfer of the court in effect signified achievement of Brazilian independence. The Portuguese prince and future King Joao VI opened Brazil's ports to the trade of friendly nations, permitted the rise of local industries, and founded the Bank of Brazil. In 1815 he elevated Brazil to the legal status of a kingdom coequal with Portugal. ln one sense, however, Brazil's new status signified the substitution of one dependence for another. Freed from Portuguese control, Brazil came under the economic dominance of England, which obtained major tariff concessions and other privileges by the Strangford Treaty of 1810 between Portugal and Great Britain. The treaty provided for the importation of British manufactures into Brazil and the export of Brazilian agricultural produce to Great Britain. One result was an influx of cheap machine-made goods that swamped the handicrafts industry of the country.
Brazilian elites took satisfaction in Brazil's new role and the growth of educational, cultural, and economic opportunities for their class. But the feeling was mixed with resentment toward the thousands of Portuguese courtiers (officials) and hangers-on who came with the court and who competed with Brazilians for jobs and favors. Thus, the change in the status of Brazil sharpened the conflict between Portuguese elites born in Brazil and elites born in Portugal and loyal to the Portuguese crown.
The event that precipitated the break with the mother country was the revolution of 1820 in Portugal. The Portuguese revolutionaries framed a liberal constitution for the kingdom, but they were conservative or reactionary in relation to Brazil. They demanded the immediate return of King Joao to Lisbon, an end to the system of dual monarchy that he had devised, and the restoration of the Portuguese commercial monopoly. Timid and vacillating, King Joao did not know which way to turn. Under the pressure of his courtiers, who hungered to return to Portugal and their lost estates, he finally approved the new constitution and sailed for Portugal. He left behind him, however, his son and heir, Pedro, and in a private letter advised him that in the event the Brazilians should demand independence, he should assume leadership of the movement and set the crown of Brazil on his head.
Soon it became clear that the Portuguese parliament intended to set the clock back by abrogating all the liberties and concessions won by Brazil since 1808. One of its decrees insisted on the immediate return of Pedro from Brazil. The pace of events moved more rapidly in 1822. On January 9, urged on by Brazilian advisers who perceived a golden opportunity to make an orderly transition to independence without the intervention of the masses, Pedro refused an order from the parliament to return to Portugal, saying famously, ""l remain."" On September 7, regarded by all Brazilians as Independence Day, he issued the even more celebrated proclamation, ""Independence or death!"" In December 1822, having overcome slight resistance by Portuguese troops, Dom Pedro was formally proclaimed constitutional Emperor of Brazil. "
R50P3
"Star DeathUntil the early- to mid-twentieth century, scientists believed that stars generate energy by shrinking. As stars contracted, it was thought, they would get hotter and hotter, giving off light in the process. This could not be the primary way that stars shine, however. If it were, they would scarcely last a million years, rather than the billions of years in age that we know they are. We now know that stars are fueled by nuclear fusion. Each time fusion takes place, energy is released as a by-product. This energy, expelled into space, is what we see as starlight. The fusion process begins when two hydrogen nuclei smash together to form a particle called the deuteron (a combination of a positive proton and a neutral neutron). Deuterons readily combine with additional protons to form helium. Helium, in turn, can fuse together to form heavier elements, such as carbon. In a typical star, merger after merger takes place until significant quantities of heavy elements are built up.
We must distinguish, at this point, between two different stellar types: Population I and Population ll, the latter being much older than the former. These groups can also be distinguished by their locations. Our galaxy, the Milky Way, is shaped like a flat disk surrounding a central bulge. Whereas Population I stars are found mainly in the galactic disk, Population II stars mostly reside in the central bulge of the galaxy and in the halo surrounding this bulge.
Population II stars date to the early stages of the universe. Formed when the cosmos was filled with hydrogen and helium gases, they initially contained virtually no heavy elements. They shine until their fusible material is exhausted. When Population II stars die, their material is spread out into space. Some of this dust is eventually incorporated into newly formed Population I stars. Though Population I stars consist mostly of hydrogen and helium gas, they also contain heavy elements (heavier than helium), which comprise about 1 or 2 percent of their mass. These heavier materials are fused from the lighter elements that the stars have collected. Thus, Population I stars contain material that once belonged to stars from previous generations. The Sun is a good example of a Population I star.
What will happen when the Sun dies? In several billion years, our mother star will burn much brighter. It will expend more and more of its nuclear fuel, until little is left of its original hydrogen. Then, at some point in the far future, all nuclear reactions in the Sun’s center will cease.
Once the Sun passes into its ""postnuclear"" phase, it will separate effectively into two different regions: an inner zone and an outer zone. While no more hydrogen fuel will remain in the inner zone, there will be a small amount left in the outer zone. Rapidly, changes will begin to take place that will serve to tear the Sun apart. The inner zone, its nuclear fires no longer burning, will begin to collapse under the influence of its own weight and will contract into a tiny hot core, dense and dim. An opposite fate will await the outer region, a loosely held-together ball of gas. A shock wave caused by the inner zone's contraction will send ripples through the dying star, pushing the stellar exterior's material farther and farther outward. The outer envelope will then grow rapidly, increasing, in a short interval, hundreds of times in size. As it expands, it will cool down by thousands of degrees. Eventually, the Sun will become a red giant star, cool and bright. It will be so large that it will occupy the whole space that used to be the Earth's orbit and so brilliant that it would be able to be seen with the naked eye thousands of light-years away. It will exist that way for millions of years, gradually releasing the material of its outer envelope into space. Finally, nothing will be left of the gaseous exterior of the Sun; all that will remain will be the hot, white core. The Sun will have become a white dwarf star. The core will shrink, giving off the last of its energy, and the Sun will finally die. "
R51P1
"Memphis: United Egypt's First CapitalThe city of Memphis, located on the Nile near the modern city of Cairo, was founded around 3100 B.C. as the first capital of a recently united Egypt. The choice of Memphis by Egypt's first kings reflects the site's strategic importance. First, and most obvious, the apex of the Nile River delta was a politically opportune location for the state's administrative center, standing between the united lands of Upper and Lower Egypt and offering ready access to both parts of the country. The older predynastic (pre-3100 B.C.) centers of power, This and Hierakonpolis, were too remote from the vast expanse of the delta, which had been incorporated into the unified state. Only a city within easy reach of both the Nile valley to the south and the more spread out, difficult terrain to the north could provide the necessary political control that the rulers of early dynastic Egypt (roughly 3000-2600 B.C.) required.
The region of Memphis must have also served as an important node for transport and communications, even before the unification of Egypt. The region probably acted as a conduit for much, if not all, of the river-based trade between northern and southern Egypt. Moreover, commodities (such as wine, precious oils, and metals) imported from the Near East by the royal courts of predynastic Upper Egypt would have been channeled through the Memphis region on their way south. In short, therefore, the site of Memphis offered the rulers of the Early Dynastic Period an ideal location for controlling internal trade within their realm, an essential requirement for a state-directed economy that depended on the movement of goods.
Equally important for the national administration was the ability to control communications within Egypt. The Nile provided the easiest and quickest artery of communication and the national capital was, again, ideally located in this respect. Recent geological surveys of the Memphis region have revealed much about its topography in ancient times. It appears that the location of Memphis may have been even more advantageous for controlling trade, transport, and communications than was previously appreciated. Surveys and drill cores have shown that the level of the Nile floodplain has steadily risen over the last five millenniums. When the floodplain was much lower, as it would have been in predynastic and early dynastic times, the outwash fans (fan-shaped deposits of sediments) of various wadis (stream-beds or channels that carry water only during rainy periods) would have been much more prominent features on the east bank. The fan associated with the Wadi Hof extended a significant way into the Nile floodplain, forming a constriction in the vicinity of Memphis. The valley may have narrowed at this point to a mere three kilometers, making it the ideal place for controlling river traffic.
Furthermore, the Memphis region seems to have been favorably located for the control not only of river-based trade but also of desert trade routes. The two outwash fans in the area gave access to the extensive wadi systems of the eastern desert. In predynastic times, the Wadi Digla may have served as a trade route between the Memphis region and the Near East, to judge from the unusual concentration of foreign artifacts found in the predynastic settlement of Maadi. Access to, and control of, trade routes between Egypt and the Near East seems to have been a preoccupation of Egypt’s rulers during the period of state formation. The desire to monopolize foreign trade may have been one of the primary factors behind the political unification of Egypt. The foundation of the national capital at the junction of an important trade route with the Nile valley is not likely to have been accidental. Moreover, the Wadis Hof and Digla provided the Memphis region with accessible desert pasturage. As was the case with the cities of Hierakonpolis and Elkab, the combination within the same area of both desert pasturage and alluvial arable land (land suitable for growing crops) was a particularly attractive one for early settlement; this combination no doubt contributed to the prosperity of the Memphis region from early predynastic times. "
R51P2
"Surface Fluids On Venus And EarthA fluid is a substance, such as a liquid or gas, in which the component particles (usually molecules) can move past one another. Fluids flow easily and conform to the shape of their containers. The geologic processes related to the movement of fluids on a planet's surface can completely resurface a planet many times. These processes derive their energy from the Sun and the gravitational forces of the planet itself. As these fluids interact with surface materials, they move particles about or react chemically with them to modify or produce materials. On a solid planet with a hydrosphere and an atmosphere, only a tiny fraction of the planetary mass flows as surface fluids. Yet the movements of these fluids can drastically alter a planet. Consider Venus and Earth, both terrestrial planets with atmospheres.
Venus and Earth are commonly regarded as twin planets but not identical twins. They are about the same size, are composed of roughly the same mix of materials, and may have been comparably endowed at their beginning with carbon dioxide and water. However, the twins evolved differently largely because of differences in their distance from the Sun. With a significant amount of internal heat, Venus may continue to be geologically active with volcanoes, rifting, and folding. However, it lacks any sign of a hydrologic system (water circulation and distribution): there are no streams, lakes oceans or glaciers. Space probes suggest that Venus may have started with as much water as Earth, but it was unable to keep its water in liquid form. Because Venus receives more heat from the Sun, water released from the interior evaporated and rose to the upper atmosphere where the Sun's ultraviolet rays broke the molecules apart. Much of the freed hydrogen escaped into space, and Venus lost its water. Without water, Venus became less and less like Earth and kept an atmosphere filled with carbon dioxide. The carbon dioxide acts as a blanket, creating an intense greenhouse effect and driving surface temperatures high enough to melt lead and to prohibit the formation of carbonate minerals. Volcanoes continually vented more carbon dioxide into the atmosphere. On Earth, liquid water removes carbon dioxide from the atmosphere and combines it with calcium, from rock weathering, to form carbonate sedimentary rocks. Without liquid water to remove carbon from the atmosphere, the level of carbon dioxide in the atmosphere of Venus remains high.
Like Venus, Earth is large enough to be geologically active and for its gravitational field to hold an atmosphere. Unlike Venus, it is just the right distance from the Sun so that temperature ranges allow water to exist as a liquid, a solid, and a gas. Water is thus extremely mobile and moves rapidly over the planet in a continuous hydrologic cycle. Heated by the Sun, the water moves in great cycles from the oceans to the atmosphere, over the landscape in river systems, and ultimately back to the oceans. As a result, Earth's surface has been continually changed and eroded into delicate systems of river valleys - a remarkable contrast to the surfaces of other planetary bodies where impact craters dominate. Few areas on Earth have been untouched by flowing water. As a result, river valleys are the dominant feature of its landscape. Similarly, wind action has scoured fine particles away from large areas, depositing them elsewhere as vast sand seas dominated by dunes or in sheets of loess (fine-grained soil deposits). These fluid movements are caused by gravity flow systems energized by heat from the Sun. Other geologic changes occur when the gases in the atmosphere or water react with rocks at the surface to form new chemical compounds with different properties. An important example of this process was the removal of most of Earths carbon dioxide from its atmosphere to form carbonate rocks. However, if Earth were a little closer to the Sun, its oceans would evaporate; if it were farther from the Sun, the oceans would freeze solid. Because liquid water was present, self-replicating molecules of carbon, hydrogen, and oxygen developed life early in Earth's history and have radically modified its surface, blanketing huge parts of the continents with greenery. Life thrives on this planet, and it helped create the planet's oxygen- and nitrogen-rich atmosphere and moderate temperatures. "
R51P3
"Population Growth in Nineteenth-Century EuropeBecause of industrialization, but also because of a vast increase in agricultural output without which industrialization would have been impossible, Western Europeans by the latter half of the nineteenth century enjoyed higher standards of living and longer, healthier lives than most of the world’s peoples. In Europe as a whole, the population rose from 188 million in 1800 to 400 million in 1900. By 1900, virtually every area of Europe had contributed to the tremendous surge of population, but each major region was at a different stage of demographic change.
Improvements in the food supply continued trends that had started in the late seventeenth century. New lands were put under cultivation, while the use of crops of American origin, particularly the potato, continued to expand. Setbacks did occur. Regional agricultural failures were the most common cause of economic recessions until 1850, and they could lead to localized famine as well. A major potato blight (disease) in 1846-1847 led to the deaths of at least one million persons in Ireland and the emigration of another million, and Ireland never recovered the population levels the potato had sustained to that point. Bad grain harvests at the same time led to increased hardship throughout much of Europe.
After 1850, however, the expansion of foods more regularly kept pace with population growth, though the poorer classes remained malnourished. Two developments were crucial. First, the application of science and new technology to agriculture increased. Led by German universities, increasing research was devoted to improving seeds, developing chemical fertilizers, and advancing livestock. After 1861, with the development of land-grant universities in the United States that had huge agricultural programs, American crop-production research added to this mix. Mechanization included the use of horse-drawn harvesters and seed drills, many developed initially in the United States. It also included mechanical cream separators and other food-processing devices that improved supply.
The second development involved industrially based transportation. With trains and steam shipping, it became possible to move foods to needy regions within Western Europe quickly. Famine (as opposed to malnutrition) became a thing of the past. Many Western European countries, headed by Britain, began also to import increasing amounts of food, not only from Eastern Europe, a traditional source, but also from the Americas, Australia, and New Zealand. Steam shipping, which improved speed and capacity, as well as new procedures for canning and refrigerating foods (particularly after 1870), was fundamental to these developments.
Europe's population growth included one additional innovation by the nineteenth century: it combined with rapid urbanization. More and more Western Europeans moved from countryside to city, and big cities grew most rapidly of all. By 1850, over half of all the people in England lived in cities, a first in human history. In one sense, this pattern seems inevitable growing numbers of people pressed available resources on the land, even when farmwork was combined with a bit of manufacturing, so people crowded into cities seeking work or other resources. Traditionally, however, death rates in cities surpassed those in the countryside by a large margin; cities had maintained population only through steady in-migration. Thus rapid urbanization should have reduced overall population growth, but by the middle of the nineteenth century this was no longer the case. Urban death rates remained high, particularly in the lower-class slums, but they began to decline rapidly.
The greater reliability of food supplies was a factor in the decline of urban death rates. Even more important were the gains in urban sanitation, as well as measures such as inspection of housing. Reformers, including enlightened doctors, began to study the causes of high death rates and to urge remediation. Even before the discovery of germs, beliefs that disease spread by ""miasmas"" (noxious forms of bad air) prompted attention to sewers and open garbage; Edwin Chadwick led an exemplary urban crusade for underground sewers in England in the 1830s. Gradually, public health provisions began to cut into customary urban mortality rates. By 1900, in some parts of Western Europe life expectancy in the cities began to surpass that of the rural areas. Industrial societies had figured out ways to combine large and growing cities with population growth, a development that would soon spread to other parts of the world. "
R52P1
"Stream DepositA large, swift stream or river can carry all sizes of particles, from clay to boulders. When the current slows down, its competence (how much it can carry) decreases and the stream deposits the largest particles in the streambed. If current velocity continues to decrease - as a flood wanes, for example - finer particles settle out on top of the large ones. Thus, a stream sorts its sediment according to size. A waning flood might deposit a layer of gravel, overlain by sand and finally topped by silt and clay. Streams also sort sediment in the downstream direction. Many mountain streams are choked with boulders and cobbles, but far downstream, their deltas are composed mainly of fine silt and clay. This downstream sorting is curious because stream velocity generally increases in the downstream direction. Competence increases with velocity, so a river should be able to transport larger particles than its tributaries carry. One explanation for downstream sorting is that abrasion wears away the boulders and cobbles to sand and silt as the sediment moves downstream over the years. Thus, only the fine sediment reaches the lower parts of most rivers.
A stream deposits its sediment in three environments: Alluvial fans and deltas form where stream gradient (angle of incline) suddenly decreases as a stream enters a flat plain, a lake, or the sea; floodplain deposits accumulate on a floodplain adjacent to the stream channel; and channel deposits form in the stream channel itself. Bars, which are elongated mounds of sediment, are transient features that form in the stream channel and on the banks. They commonly form in one year and erode the next. Rivers used for commercial navigation must be recharged frequently because bars shift from year to year. Imagine a winding stream. The water on the outside of the curve moves faster than the water on the inside. The stream erodes its outside bank because the current's inertia drives it into the outside bank. At the same time, the slower water on the inside point of the bend deposits sediment, forming a point bar. A mid-channel bar is a sandy and gravelly deposit that forms in the middle of a stream channel.
Most streams flow in a single channel. In contrast, a braided stream flows in many shallow, interconnecting channels. A braided stream forms where more sediment is supplied to a stream than it can carry. The stream dumps the excess sediment, forming mid-channel bars. The bars gradually fill a channel, forcing the stream to overflow its banks and erode new channels. As a result, a braided stream flows simultaneously in several channels and shifts back and forth across its floodplain. Braided streams are common in both deserts and glacial environments because both produce abundant sediment. A desert yields large amounts of sediment because it has little or no vegetation to prevent erosion. Glaciers grind bedrock into fine sediment, which is carried by streams flowing from the melting ice. If a steep mountain stream flows onto a flat plain, its gradient and velocity decrease sharply. As a result, it deposits most of its sediment in a fan-shaped mound called an alluvial fan. Alluvial fans are common in many arid and semiarid mountainous regions.
A stream also slows abruptly where it enters the still water of a lake or ocean. The sediment settles out to form a nearly flat landform called a delta. Part of the delta lies above water level, and the remainder lies slightly below water level. Deltas are commonly fan-shaped, resembling the Greek letter ""delta"" (?). Both deltas and alluvial fans change rapidly. Sediment fills channels (waterways), which are then abandoned while new channels develop as in a braided stream. As a result, a stream feeding a delta or fan splits into many channels called distributaries. A large delta may spread out in this manner until it covers thousands of square kilometers. Most fans, however, are much smaller, covering a fraction of a square kilometer to a few square kilometers. The Mississippi River has flowed through seven different delta channels during the past 5,000 to 6,000 years. But in recent years, engineers have built great systems of levees (retaining walls) in attempts to stabilize the channels. "
R52P2
"Natufian CultureIn the archaeological record of the Natufian period, from about 12,500 to 10,200 years ago, in the part of the Middle East known as the Levant - roughly east of the Mediterranean and north of the Arabian Peninsula - we see clear evidence of agricultural origins. The stone tools of the Natufians included many sickle-shaped cutting blades that show a pattern of wear characteristic of cereal harvesting. Also, querns (hand mills) and other stone tools used for processing grain occur in abundance at Natufian sites, and many such tools show signs of long, intensive use. Along with the sickle blades are many grinding stones, primarily mortars and pestles of limestone or basalt. There is also evidence that these heavy grinding stones were transported over long distances, more than 30 kilometers in some cases, and this is not something known to have been done by people of preceding periods. Fishhooks and weights for sinking fishing nets attest to the growing importance of fish in the diet in some areas. Stone vessels indicate an increased need for containers, but there is no evidence of Natufian clay working or pottery. Studies of the teeth of Natufians also strongly suggest that these people specialized in collecting cereals and may have been cultivating them and in the process of domesticating them, but they were also still hunter-foragers who intensively hunted gazelle and deer in more lush areas and wild goats and equids in more arid zones.
The Natufians had a different settlement pattern from that of their predecessors. Some of their base camps were far larger (over 1,000 square meters) than any of those belonging to earlier periods, and they may have lived in some of these camps for half the year or even more. In some of the camps, people made foundations and other architectural elements out of limestone blocks. Trade in shell, obsidian, and other commodities seems to have been on the rise, and anthropologists suspect that the exchange of perishables (such as skins, foodstuffs) and salt was also on the increase. With the growing importance of wild cereals in the diet, salt probably became for the first time a near necessity: people who eat a lot of meat get many essential salts from this diet, but diets based on cereals can be deficient in salts. Salt was probably also important as a food preservative in early villages.
As always, there is more to a major cultural change than simply a shift in economics. The Natufians made (and presumably wore) beads and pendants in many materials, including gemstones and marine shells that had to be imported, and it is possible that this ornamentation actually reflects a growing sense of ethnic identity and perhaps some differences in personal and group status. Cleverly carved figurines of animals, women, and other subjects occur in many sites, and Natufian period cave paintings have been found in Anatolia, Syria, and Iran. More than 400 Natufian burials have been found, most of them simple graves set in house floors. As archaeologist Belfer-Cohen notes, these burials may reflect an ancestor cult and a growing sense of community emotional ties and attachment to a particular place, and toward the end of the Natufian period, people in this area were making a strict separation between living quarters and burial grounds. In contrast with the Pleistocene cultures of the Levant, Natufian culture appears to have experienced considerable social change.
The question of why the Natufians differed from their predecessors in these and other ways and why they made these first steps toward farming as a way of life remains unclear. There were climate changes, of course, and growing aridity and rising population densities may have forced them to intensify the exploitation of cereals, which in turn might have stimulated the development of sickles and other tools and the permanent communities that make agriculture efficient. But precisely how these factors interacted with others at play is poorly understood. "
R52P3
"Early Food Production in Sub-Saharan AfricaAt the end of the Pleistocene (around 10,000 B.C.), the technologies of food production may have already been employed on the fringes of the rain forests of western and central Africa, where the common use of such root plants as the African yam led people to recognize the advantages of growing their own food. The yam can easily be resprouted if the top is replanted. This primitive form of ""vegeculture"" (cultivation of root and tree crops) may have been the economic tradition onto which the cultivation of summer rainfall cereal crops was grafted as it came into use south of the grassland areas on the Sahara's southern borders.
As the Sahara dried up after 5000 B.C., pastoral peoples (cattle herders) moved southward along major watercourses into the savanna belt of West Africa and the Sudan. By 3000 B.C., just as ancient Egyptian civilization was coming into being along the Nile, they had settled in the heart of the East African highlands far to the south. The East African highlands are ideal cattle country and the home today of such famous cattle-herding peoples as the Masai. The highlands were inhabited by hunter-gatherers living around mountains near the plains until about 3300 B.C., when the first cattle herders appeared. These cattle people may have moved between fixed settlements during the wet and dry seasons, living off hunting in the dry months and their own livestock and agriculture during the rains.
As was the case elsewhere, cattle were demanding animals in Africa. They required water at least every 24 hours and large tracts of grazing grass if herds of any size were to be maintained. The secret was the careful selection of grazing land, especially in environments where seasonal rainfall led to marked differences in graze quality throughout the year. Even modest cattle herds required plenty of land and considerable mobility. To acquire such land often required moving herds considerable distances, even from summer to winter pastures. At the same time, the cattle owners had to graze their stock in tsetse-fly-free areas. The only protection against human and animal sleeping sickness, a disease carried by the tsetse fly, was to avoid settling or farming such areas - a constraint severely limiting the movements of cattle-owning farmers in eastern and central Africa. As a result, small cattle herds spread south rapidly in areas where they could be grazed. Long before cereal agriculture took hold far south of the Sahara, some hunter-gatherer groups in the savanna woodlands of eastern and southern Africa may have acquired cattle, and perhaps other domesticated animals, by gift exchange or through raids on herding neighbors.
Contrary to popular belief: there is no such phenomenon as ""pure"" pastoralists, a society that subsists on its herds alone. The Saharan herders who moved southward to escape drought were almost certainly also cultivating sorghum, millet; and other tropical rainfall crops. By 1500 B.C., cereal agriculture was widespread throughout the savanna belt south of the Sahara. Small farming communities dotted the grasslands and forest margins of eastern West Africa, all of them depending on what is called shifting agriculture. This form of agriculture involved clearing woodland, burning the felled brush over the cleared plot, mixing the ash into the soil, and then cultivating the prepared fields. After a few years, the soil was exhausted, so the farmer moved on, exploiting new woodland and leaving the abandoned fields to lie fallow. Shifting agriculture, often called slash-and-burn, was highly adaptive for savanna farmers without plows, for it allowed cereal farming with the minimal expenditure of energy.
The process of clearance and burning may have seemed haphazard to the uninformed eye, but it was not. Except in favored areas, such as regularly inundated floodplains: tropical Africa's soils were of only moderate to low fertility. The art of farming was careful soil selection, that is, knowing which soils were light and easily cultivable, could be readily turned with small hoes, and would maintain their fertility over several years' planting, for cereal crops rapidly remove nitrogen and other nutrients from the soil. Once it had taken hold: slash-and-burn agriculture expanded its frontiers rapidly as village after village took up new lands, moving forward so rapidly that one expert has estimated it took a mere two centuries to cover 2,000 kilometers from eastern to southern Africa. "
R53P1
"Evidence of the Earliest WritingAlthough literacy appeared independently in several parts of the prehistoric world, the earliest evidence of writing is the cuneiform Sumerian script on the clay tablets of ancient Mesopotamia, which, archaeological detective work has revealed, had its origins in the accounting practices of commercial activity. Researchers demonstrated that preliterate people, to keep track of the goods they produced and exchanged, created a system of accounting using clay tokens as symbolic representations of their products. Over many thousands of years, the symbols evolved through several stages of abstraction until they became wedge- shaped (cuneiform) signs on clay tablets, recognizable as writing.
The original tokens (circa 8500 B.C.E.) were three-dimensional solid shapes-tiny spheres, cones, disks, and cylinders. A debt of six units of grain and eight head of livestock, for example might have been represented by six conical and eight cylindrical tokens. To keep batches of tokens together, an innovation was introduced (circa 3250 B. C. E.) whereby they were sealed inside clay envelopes that could be broken open and counted when it came time for a debt to be repaid. But because the contents of the envelopes could easily be forgotten, two-dimensional representations of the three-dimensional tokens were impressed into the surface of the envelopes before they were sealed. Eventually, having two sets of equivalent symbols-the internal tokens and external markings-came to seem redundant, so the tokens were eliminated (circa 3250-3100 B.C.E.), and only solid clay tablets with two-dimensional symbols were retained. Over time, the symbols became more numerous, varied, and abstract and came to represent more than trade commodities, evolving eventually into cuneiform writing.
The evolution of the symbolism is reflected in the archaeological record first of all by the increasing complexity of the tokens themselves. The earliest tokens, dating from about 10,000 to 6,000 years ago, were of only the simplest geometric shapes. But about 3500 B.C.E., more complex tokens came into common usage, including many naturalistic forms shaped like miniature tools, furniture, fruit, and humans. The earlier, plain tokens were counters for agricultural products, whereas the complex ones stood for finished products, such as bread, oil, perfume, wool, and rope, and for items produced in workshops, such as metal, bracelets, types of cloth, garments, mats, pieces of furniture, tools, and a variety of stone and pottery vessels. The signs marked on clay tablets likewise evolved from simple wedges, circles, ovals, and triangles based on the plain tokens to pictographs derived from the complex tokens.
Before this evidence came to light, the inventors of writing were assumed by researchers to have been an intellectual elite. Some, for example, hypothesized that writing emerged when members of the priestly caste agreed among themselves on written signs. But the association of the plain tokens with the first farmers and of the complex tokens with the first artisans-and the fact that the token-and-envelope accounting system invariably represented only small-scale transactions-testifies to the relatively modest social status of the creators of writing.
And not only of literacy, but numeracy (the representation of quantitative concepts) as well. The evidence of the tokens provides further confirmation that mathematics originated in people's desire to keep records of flocks and other goods. Another immensely significant step occurred around 3100 B.C.E., when Sumerian accountants extended the token-based signs to include the first real numerals. Previously, units of grain had been represented by direct one-to-one correspondence―by repeating the token or symbol for a unit of grain the required number of times. The accountants, however, devised numeral signs distinct from commodity signs, so that eighteen units of grain could be indicated by preceding a single grain symbol with a symbol denoting ""18."" Their invention of abstract numerals and abstract counting was one of the most revolutionary advances in the history of mathematics.
What was the social status of the anonymous accountants who produced this breakthrough? The immense volume of clay tablets unearthed in the ruins of the Sumerian temples where the accounts were kept suggests a social differentiation within the scribal class, with a virtual army of lower-ranking tabulators performing the monotonous job of tallying commodities. We can only speculate as to how high or low the inventors of true numerals were in the scribal hierarchy, but it stands to reason that this laborsaving innovation would have been the brainchild of the lower-ranking types whose drudgery it eased. "
R53P2
"Rain Forest SoilsOn viewing the lush plant growth of a tropical rain forest, most people would conclude that the soil beneath it is rich in nutrients. However, although rain forest soils are highly variable, they have in common the fact that abundant rainfall washes mineral nutrients out of them and into streams. This process is known as leaching. Because of rain leaching, most tropical rain forest soils have low to very low mineral nutrient content, in dramatic contrast to mineral-rich grassland soils. Tropical forest soils also often contain particular types of clays that, unlike the mineral-binding clays of temperate forest soils, do not bind mineral ions well. Aluminum is the dominant cation (positively charged ion) present in tropical soils; but plants do not require this element, and it is moderately toxic to a wide range of plants. Aluminum also reduces the availability of phosphorus, an element in high demand by plants.
High moisture and temperatures speed the growth of soil microbes that decompose organic compounds, so tropical soils typically contain far lower amounts of organic materials (humus) than do other forest or grassland soils. Because organic compounds help loosen compact clay soils, hold water, and bind mineral nutrients, the relative lack of organic materials in tropical soils is deleterious to plants. Plant roots cannot penetrate far into hard clay soils, and during dry periods, the soil cannot hold enough water to supply plant needs. Because the concentration of dark-colored organic materials is low in tropical soils, they are often colored red or yellow by the presence of iron, aluminum: and manganese oxides; when dry, these soils become rock hard. The famous Cambodian temples of Angkor Wat, which have survived for many centuries, were constructed from blocks of such hard rain forest soils.
Given such poor soils, how can lush tropical forests exist? The answer is that the forest's minerals are held in its living biomass-the trees and other plants and the animals. In contrast to grasslands, where a large proportion of plant biomass is produced underground, that of tropical forests is nearly all aboveground. Dead leaves, branches, and other plant parts, as well as the wastes and bodies of rain forest animals, barely reach the forest floor before they are rapidly decayed by abundant decomposers-bacterial and fungal. Minerals released by decay are quickly absorbed by multitudinous shallow, fine tree feeder roots and stored in plant tissues. Many tropical rain forest plants (like those in other forests) have mycorrhizal (fungus-root) partners whose delicate hyphae spread through great volumes of soil, from which they release and absorb minerals and ferry them back to the host plant in exchange for needed organic compounds. The fungal hyphae are able to absorb phosphorus that plant roots could not themselves obtain from the very dilute soil solutions, and fungal hyphae can transfer mineral nutrients from one forest plant to another. Consequently, tropical rain forests typically have what are known as closed nutrient systems, in which minerals are handed off from one organism to another with little leaking through to the soil. When mineral nutrients do not spend much time in the soil, they cannot be leached into streams. Closed nutrient systems have evolved in response to the leaching effects of heavy tropical rainfall. Evidence for this conclusion is that nutrient systems are more open in the richest tropical soils and tightest in the poorest soils.
The growth of organisms is dependent on the availability of nutrients, none of which is more important than nitrogen. Although there is an abundant supply of nitrogen in Earth's atmosphere, it cannot be absorbed by plants unless it is ""fixed,"" or combined chemically with other elements to form nitrogen compounds. Nitrogen-fixing bacteria help tropical rain forest plants cope with the poor soils there by supplying them with needed nitrogen. Many species of tropical rain forest trees belong to the legume family, which is known for associations of nitrogen-fixing bacteria within root nodules. Also, cycads (a type of tropical plant that resembles a palm tree) produce special aboveground roots that harbor nitrogen-fixing cyanobacteria. By growing above the ground, the roots are exposed to sunlight, which the cyanobacteria require for growth. Nitrogen fixation by free-living bacteria in tropical soils is also beneficial. "
R53P3
"Paleolithic Cave PaintingsIn any investigation of the origins of art, attention focuses on the cave paintings created in Europe during the Paleolithic era (c. 40,000-10,000 years ago) such as those depicting bulls and other animals in the Lascaux cave in France. Accepting that they are the best preserved and most visible signs of what was a global creative explosion, how do we start to explain their appearance? Instinctively, we may want to update the earliest human artists by assuming that they painted for the sheer joy of painting. The philosophers of Classical Greece recognized it as a defining trait of humans to ""delight in works of imitation""-to enjoy the very act and triumph of representation. If we were close to a real lion or snake, we might feel frightened. But a well- executed picture of a lion or snake will give us pleasure. Why suppose that our Paleolithic ancestors were any different?
This simple acceptance of art for art's sake has a certain appeal. To think of Lascaux as a gallery allows it to be a sort of special viewing place where the handiwork of accomplished artists might be displayed. Plausibly, daily existence in parts of Paleolithic Europe may not have been so hard, with an abundance of ready food and therefore the leisure time for art. The problems with this explanation, however, are various. In the first place, the proliferation of archaeological discoveries-and this includes some of the world's innumerable rock art sites that cannot be dated-has served to emphasize a remarkably limited repertoire of subjects. The images that recur are those of animals. Human figures are unusual, and when they do make an appearance, they are rarely done with the same attention to form accorded to the animals. If Paleolithic artists were simply seeking to represent the beauty of the world around them, would they not have left a far greater range of pictures-of trees, flowers, of the Sun and the stars?
A further question to the theory of art for art's sake is posed by the high incidence of Paleolithic images that appear not to be imitative of any reality whatsoever. These are geometrical shapes or patterns consisting of dots or lines. Such marks may be found isolated or repeated over a particular surface but also scattered across more recognizable forms. A good example of this may be seen in the geologically spectacular grotto of Pêche Merle, in the Lot region of France. Here we encounter some favorite animals from the Paleolithic repertoire-a pair of stout-bellied horses. But over and around the horses' outlines are multiple dark spots, daubed in disregard for the otherwise naturalistic representation of animals. What does such patterning imitate? There is also the factor of location. The caves of Lascaux might conceivably qualify as underground galleries, but many other paintings have been found in recesses totally unsuitable for any kind of viewing-tight nooks and crannies that must have been awkward even for the artists to penetrate, let alone for anyone else wanting to see the art.
Finally, we may doubt the notion that the Upper Paleolithic period was a paradise in which food came readily, leaving humans ample time to amuse themselves with art. For Europe it was still the Ice Age. An estimate of the basic level of sustenance then necessary for human survival has been judged at 2200 calories per day. This consideration, combined with the stark emphasis upon animals in the cave art, has persuaded some archaeologists that the primary motive behind Paleolithic images must lie with the primary activity of Paleolithic people: hunting.
Hunting is a skill. Tracking, stalking, chasing, and killing the prey are difficult, sometimes dangerous activities. What if the process could be made easier-by art? In the early decades of the twentieth century, Abbé Henri Breuil argued that the cave paintings were all about ""sympathetic magic. "" The artists strived diligently to make their animal images evocative and realistic because they were attempting to capture the spirit of their prey. What could have prompted their studious attention to making such naturalistic, recognizable images? According to Breuil, the artists may have believed that if a hunter were able to make a true likeness of some animal, then that animal was virtually trapped. Images, therefore, may have had the magical capacity to confer success or luck in the hunt. "
R54P1
"Elements of LifeThe creation of life requires a set of chemical elements for making the components of cells. Life on Earth uses about 25 of the 92 naturally occurring chemical elements, although just 4 of these elements-oxygen, carbon, hydrogen, and nitrogen-make up about 96 percent of the mass of living organisms. Thus, a first requirement for life might be the presence of most or all of the elements used by life.
Interestingly, this requirement can probably be met by almost any world. Scientists have determined that all chemical elements in the universe besides hydrogen and helium (and a trace amount of lithium) were produced by stars. These are known as heavy elements because they are heavier than hydrogen and helium. Although all of these heavy elements are quite rare compared to hydrogen and helium, they are found just about everywhere.
Heavy elements are continually being manufactured by stars and released into space by stellar deaths, so their amount compared to hydrogen and helium gradually rises with time. Heavy elements make up about 2 percent of the chemical content (by mass) of our solar system, the other 98 percent is hydrogen and helium. In some very old star systems, which formed before many heavy elements were produced, the heavy-element share may be less than 0.1 percent. Nevertheless, every star system studied has at least some amount of all the elements used by life.Moreover, when planetesimals-small, solid objects formed in the early solar system that may accumulate to become planets-condense within a forming star system, they are inevitably made from heavy elements because the more common hydrogen and helium remain gaseous. Thus, planetesimals everywhere should contain the elements needed for life, which means that objects built from planetesimals-planets, moons, asteroids, and comets-also contain these elements. The nature of solar-system formation explains why Earth contains all the elements needed for life, and it is why we expect these elements to be present on other worlds throughout our solar system, galaxy, and universe.
Note that this argument does not change, even if we allow for life very different from life on Earth. Life on Earth is carbon based, and most biologists believe that life elsewhere is likely to be carbon based as well. However, we cannot absolutely rule out the possibility of life with another chemical basis, such as silicon or nitrogen. The set of elements (or their relative proportions) used by life based on some other element might be somewhat different from that used by carbon-based life on Earth. But the elements are still products of stars and would still be present in planetesimals everywhere. No matter what kinds of life we are looking for, we are likely to find the necessary elements on almost every planet, moon, asteroid, and comet in the universe.
A somewhat stricter requirement is the presence of these elements in molecules that can be used as ready-made building blocks for life, just as early Earth probably had an organic soup of amino acids and other complex molecules. Earth's organic molecules likely came from some combination of three sources: chemical reactions in the atmosphere, chemical reactions near deep-sea vents in the oceans, and molecules carried to Earth by asteroids and comets. The first two sources can occur only on worlds with atmospheres or oceans, respectively. But the third source should have brought similar molecules to nearly all worlds in our solar system.
Studies of meteorites and comets suggest that organic molecules are widespread among both asteroids and comets. Because each body in the solar system was repeatedly struck by asteroids and comets during the period known as the heavy bombardment (about 4 billion years ago), each body should have received at least some organic molecules. However, these molecules tend to be destroyed by solar radiation on surfaces unprotected by atmospheres. Moreover, while these molecules might stay intact beneath the surface (as they evidently do on asteroids and comets), they probably cannot react with each other unless some kind of liquid or gas is available to move them about. Thus, if we limit our search to worlds on which organic molecules are likely to be involved in chemical reactions, we can probably rule out any world that lacks both an atmosphere and a surface or subsurface liquid medium, such as water. "
R54P2
"Overkill of the North American MegafaunaThousands of years ago, in North America's past, all of its megafauna-large mammals such as mammoths and giant bears-disappeared. One proposed explanation for this event is that when the first Americans migrated over from Asia, they hunted the megafauna to extinction. These people, known as the Clovis society after a site where their distinctive spear points were first found, would have been able to use this food source to expand their population and fill the continent rapidly. Yet many scientists argue against this ""Pleistocene overkill"" hypothesis. Modern humans have certainly been capable of such drastic effects on animals, but could ancient people with little more than stone spears similarly have caused the extinction of numerous species of animals? Thirty-five genera or groups of species (and many individual species) suffered extinction in North America around 11,000 B.C., soon after the appearance and expansion of Paleo-lndians throughout the Americas (27 genera disappeared completely, and another 8 became locally extinct, surviving only outside North America).
Although the climate changed at the end of the Pleistocene, warming trends had happened before. A period of massive extinction of large mammals like that seen about 11,000 years ago had not occurred during the previous 400,000 years, despite these changes. The only apparently significant difference in the Americas 11,000 years ago was the presence of human hunters of these large mammals. Was this coincidence or cause-and-effect?
We do not know. Ecologist Paul S. Martin has championed the model that associates the extinction of large mammals at the end of the Pleistocene with human predation. With researcher J. E. Mosimann, he has co-authored a work in which a computer model showed that in around 300 years, given the right conditions, a small influx of hunters into eastern Beringia 12,000 years ago could have spread across North America in a wave and wiped out game animals to feed their burgeoning population.
The researchers ran the model several ways, always beginning with a population of 100 humans in Edmonton, in Alberta, Canada, at 11,500 years ago. Assuming different initial North American big-game-animal populations (75-150 million animals) and different population growth rates for the human settlers (0.65%-3.5%), and varying kill rates, Mosimann and Martin derived figures of between 279 and 1,157 years from initial contact to big-game extinction. Many scholars continue to support this scenario. For example, geologist Larry Agenbroad has mapped the locations of dated Clovis sites alongside the distribution of dated sites where the remains of wooly mammoths have been found in both archaeological and purely paleontological contexts. These distributions show remarkable synchronicity (occurrence at the same time).
There are, however, many problems with this model. Significantly, though a few sites are quite impressive, there really is very little archaeological evidence to support it. Writing in 1982, Martin himself admitted the paucity of evidence; for example, at that point, the remains of only 38 individual mammoths had been found at Clovis sites. In the years since, few additional mammoths have been added to the list; there are still fewer than 20 Clovis sites where the remains of one or more mammoths have been recovered, a minuscule proportion of the millions that necessarily would have had to have been slaughtered within the overkill scenario.
Though Martin claims the lack of evidence actually supports his model-the evidence is sparse because the spread of humans and the extinction of animals occurred so quickly-this argument seems weak. And how could we ever disprove it? As archaeologist Donald Grayson points out, in other cases where extinction resulted from the quick spread of human hunters-for example, the extinction of the moa, the large flightless bird of New Zealand-archaeological evidence in the form of remains is abundant. Grayson has also shown that the evidence is not so clear that all or even most of the large herbivores in late Pleistocene America became extinct after the appearance of Clovis. Of the 35 extinct genera, only 8 can be confidently assigned an extinction date of between 12,000 and 10,000 years ago. Many of the older genera, Grayson argues, may have succumbed before 12,000 B.C., at least half a century before the Clovis showed up in the American West. "
R54P3
"The Commercialization of LumberIn nineteenth-century America, practically everything that was built involved wood. Pine was especially attractive for building purposes. It is durable and strong, yet soft enough to be easily worked with even the simplest of hand tools. It also floats nicely on water, which allowed it to be transported to distant markets across the nation. The central and northern reaches of the Great Lakes states-Michigan, Wisconsin, and Minnesota-all contained extensive pine forests as well as many large rivers for floating logs into the Great Lakes, from where they were transported nationwide.
By 1860, the settlement of the American West along with timber shortages in the East converged with ever-widening impact on the pine forests of the Great Lakes states. Over the next 30 years, lumbering became a full-fledged enterprise in Michigan, Wisconsin, and Minnesota. Newly formed lumbering corporations bought up huge tracts of pineland and set about systematically cutting the trees. Both the colonists and the later industrialists saw timber as a commodity, but the latter group adopted a far more thorough and calculating approach to removing trees. In this sense, what happened between 1860 and 1890 represented a significant break with the past. No longer were farmers in search of extra income the main source for shingles, firewood, and other wood products. By the 1870s, farmers and city dwellers alike purchased forest products from large manufacturing companies located in the Great Lakes states rather than chopping wood themselves or buying it locally.
The commercialization of lumbering was in part the product of technological change. The early, thick saw blades tended to waste a large quantity of wood, with perhaps as much as a third of the log left behind on the floor as sawdust or scrap. In the 1870s, however, the British-invented band saw, with its thinner blade, became standard issue in the Great Lakes states' lumber factories. Meanwhile, the rise of steam-powered mills streamlined production by allowing for the more efficient, centralized, and continuous cutting of lumber. Steam helped to automate a variety of tasks, from cutting to the carrying away of waste. Mills also employed steam to heat log ponds, preventing them from freezing and making possible year-round lumber production.
For industrial lumbering to succeed, a way had to be found to neutralize the effects of the seasons on production. Traditionally, cutting took place in the winter, when snow and ice made it easier to drag logs on sleds or sleighs to the banks of streams. Once the streams and lakes thawed, workers rafted the logs to mills, where they were cut into lumber in the summer. If nature did not cooperate-if the winter proved dry and warm, if the spring thaw was delayed-production would suffer. To counter the effects of climate on lumber production, loggers experimented with a variety of techniques for transporting trees out of the woods. In the 1870s, loggers in the Great Lakes states began sprinkling water on sleigh roads, giving them an artificial ice coating to facilitate travel. The ice reduced the friction and allowed workers to move larger and heavier loads.
But all the sprinkling in the world would not save a logger from the threat of a warm winter. Without snow the sleigh roads turned to mud. In the 1870s, a set of snowless winters left lumber companies to ponder ways of liberating themselves from the seasons. Railroads were one possibility. At first, the remoteness of the pine forests discouraged common carriers from laying track. But increasing lumber prices in the late 1870s combined with periodic warm, dry winters compelled loggers to turn to iron rails. By 1887, 89 logging railroads crisscrossed Michigan, transforming logging from a winter activity into a year-round one.
Once the logs arrived at a river, the trip downstream to a mill could be a long and tortuous one. Logjams (buildups of logs that prevent logs from moving downstream) were common-at times stretching for 10 miles-and became even more frequent as pressure on the northern Midwest pinelands increased in the 1860s. To help keep the logs moving efficiently, barriers called booms (essentially a chain of floating logs) were constructed to control the direction of the timber. By the 1870s, lumber companies existed in all the major logging areas of the northern Midwest. "
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