【IBT听力分析】香草鱼的听力帖

香草鱼UID：3125484

TPO-21 Conversation1
Narrator
Listen to a conversation between a student and a professor.

Professor Excuse me, can I help you? You look a little lost.

Student Yeah, I am. This is my first day on campus, and I don’t know where anything is.

Professor Can’t find your orientation session?

Student Uh-huh. What a way to begin! Lost going to orientation

Professor Well, my guess is in the auditorium, that’s where they usually are.

Student You’re right, the general ones. I went to one of those sessions ealier 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.

Professor 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.

Student 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.

Professor 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.

Student Who is Johnson anyway?

Professor Oh, one of the early professors here. Unfortunately, I thinks his ideas are going out of style. Science kept marching forward.

Student 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.

Professor Um... so do you know what kind of engineering you want to specialize in?

Student Yeah, aerospace engineering.

Professor 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?

Student Yeah, I know. And a couple of students who graduated from here became astronauts and orbited the Earth.

Professor 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.

Student Oh, cool. Actually, I want to get a minor in math.

Professor 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.

Student I’m glad to hear you say that.



TPO 21 Lecture 1 Astronomy(Geocentric&Heliocentric theory)
Narrator Listen to part of a lecture in a history of science class. Aristarchus-Heliocentric Theory



Professor 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 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 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 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 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.


TPO21 Lecture 2 Computer Science(Software Development)
Narrator Listen to part of a lecture in a Computer Science class. The professor is discussing software engineering.

Professor 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?

Student Um... just a quick thing. Bugs is the word for problems in the program code, right?

Professor
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’ circuits1. 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?

Student And they are different people?

Professor They are generally completely different group of people. My personal opinion is that they have to be different groups of people because developers often have a bias for 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 to 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 construtive, 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 are two projects that I worked on a couple of years ago. One, which I’ll call Project Split, well, 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 on the table. Um... and ... and the developers were very defensive about the feedback.

Student Well, if bugs are being pointed out they wouldn’t be too happy since its their work.

Professor Exactly. Now, ‘cause 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 and 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.

Student Ok, and what about Project Unity? How was it different?

Professor
Um... this was different because two teams worked closely together during the defect meetings, instead of put up walls. Um... we didn’t even talked about, you know, who should fix this, who is at fault2. We all acknowledge what needed to be fixed. So if we had ten bugs, we said, ‘Hey, you know what? Let’s do this one first ‘cause this would expose another whole bunch of defects that we haven’t even seen yet.’ So we were being proactive3 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.

香草鱼UID：3125484

TPO21 Conversation 2
Narrator Listen to a conversation between a student and her public relations professor.

Student 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.

Professor 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.

Student Everyone thinks, public relations, eh, PR is easy, but there’s a lot to it. You really got to know what you are doing.

Professor Absolutely. So, Stacy, your email implied that you needed my advice about graduate school?

Student 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.

Professor About?

Student Well, I endured accounting and economics in high school and barely stayed awake, they were so ...

Professor Ok, Ok. I hear you. Eh...语气题 you say you wanted a master’s in marketing, you have got one more semester till graduation. Have you taken any marketing courses yet?

Student No, I figured I’ve got the marketing basis already since I have take every PR in communication courses offered here.

Professor 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 buiding 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 audience.

Student 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?

Professor 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 its marketing strategy?

Student You mean how the university invites local residents to attend certain lectures and classes for free?

Professor 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.

Student That’s why I want to focus on marketing in graduate school. Wouldn’t having expertise in PR and marketing giving me more career options?

Professor Yeah, but you’ll also want to enjoy your work. So for you electives, why don’t you take advertising principles and intro to 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.

Student I wish my advisor had suggested those courses.

Professor Well, I am someone who has worked in both marketing and PR, so I can offer a different perspective than someone who only teaches ...



TPO21 Lecture3 Biology(Snake Evolution)
Narrator Listen to part of a lecture in a biology class.

Professor 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 secrete 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.上面主要讲venom snake的分类和Colubrids蛇,这段主要是解答第二题和部分解答第一题,强调这段的行文用途

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 understanding 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.上面两段讲的一个意思,解答25题

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 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 inmoblize 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 becoming 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 apparatus4 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-fetched5, 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.



TPO21 Lecture 4 Art History(Alice Neel)
Narrator Listen to part of a lecture in an Art History class.

Professor
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 prestigious6, 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?

Student 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.

Professor Ok, good. So Neel combined realism with, well, actually, with expressionism. And that is? We, we just covered this.语气题

Student Um... It’s into emotion, like artists are trying to, well, express themselves through the painting, right?

Professor
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 overrides7 objective representation. Ok, so, Alice Neel combined these two styles ... Yes?

Student Em... How is that even possible? How can your portray something exactly as it is and at the same time distort it with emotions? I don’t get it.

Professor
All right, good question. It is actually a good lead-in8 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.

1.First, Neel’s use of bold color. All right? You’ll see she uses color to convey emtion 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.

Student But didn’t a lot of expressionist painters do that? So really your are 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?

Professor 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 stance9 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 of10 three thousand paintings. If your looked at them, it is like this gallery of the whole century, an enomous 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.

香草鱼UID：3125484

TPO 22 Conversation 1 (Faculty Advisor)

Narrator: Listen to a conversation between a student and a faculty advisor for the university newspaper.
Student: Hi, I am sorry to bother you, but…
Faculty advisor: Yes?
Student: This is about the newspaper.
Faculty Advisor: 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.
Student: Well, my problem was with the writing actually, with an article that was published in yesterday’s newspaper. Faculty Advisor: Oh? Which one?
Student: The one about the student government and its president Sally Smith.
Faculty Advisor: Is this something to do with what the editor wrote about the statue? Eh, the statue at the main entrance of the university?
Student: 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 at the very least an apology to Sally.
Faculty Advisor: 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.
第二题用排除法做会好些
Student: 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.
Faculty Advisor: Wait a minute. Remind me.
Student: 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?
Faculty Advisor: Haven’t you heard the saying “all publicity is good publicity”?
Student: Well…
Faculty Advisor: 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.
Student: But this article…
Faculty Advisor: 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 just poking fun at Sally, but the whole idea that our school is sort of rural, and you know, not cosmopolitan.
Student: Well, none of us thought it was very funny.
Faculty Advisor: Well, sometimes it’s best just to roll with it. It is just a cliché; everybody knows it is not true.
Student: But I thought we could expect better than that here.
Faculty Advisor: 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.]
Student: [Really? She would let us do that? ] Didn’t she write it?
Faculty Advisor: 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.




TPO22 Lecture 1 (Anthropology)
Narrator: Listen to part of a lecture in an anthropology class.

Professor: One of the big questions when we look at prehistory is why did the earliest 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 increase 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 middleclass comprised of managers and merchants, and a lower class of crop 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.



TPO22 Lecture 2 (Astronomy)
Narrator: Listen to part of a lecture in an astronomy class.

Professor: Today, I want to talk about a paradox the ties in with the topic we discuss 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 taking from the oldest rocks on Earth?
Student: Eh… Like pebbles, fossilized algae?
Professor: Right. And on Mars?
Student: Dry channels?
Professor: Good. All evidence of water in liquid form, large quantities of it. Now, remember when we talked about star formation, we said that as a 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…
Student: There would have been ice on Earth or Mars?
Professor: 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 atmospheres of Earth and Mars might have caused temperatures to raise enough to compensate for the low heat the young Sun provided. And so it would have been warm enough on these planets for liquid water to exist. So, what gas do you think was the first suspect in causing the greenhouse effect?
Student: Um…carbon dioxide, I guess. Like today?
Professor: 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 might 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 is 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.
Student: You mean the Sun had more mass when it was young?
Professor: 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.
Student: Is that possible?
Professor: Actually, the Sun is constantly losing mass through the solar wind, a stream of 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 Mars, not enough to have caused liquid water.
Student: Maybe the solar wind was stronger then?
Professor: 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 seven percent more mass would be required.
Student: So the young Sun had seven percent more mass than our Sun?
Professor: Well, we don’t know. According to observations of young Sun like stars, our Sun may have lost as much as six percent 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.

香草鱼UID：3125484

TPO22 Conversation 2 (Professor)
Narrator: Listen to part of a conversation between a student and his music history professor.

Student: So, I was wondering what I could do to improve my paper before the final draft is due.
Professor: 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.
Student: 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.
Professor: That’s not necessarily an advantage. Familiarity sometimes makes it hard to see things objectively.
Student: So I shouldn’t write about my grandmother?
Professor: 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.
Student: 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.
Professor: Ok. I see what happened now. By broader context, I mean how the concert relates to some period in music history.
Student: I see. Ok. Um… I have an idea.
Professor: Ok.
Student: Well, as you read in my paper, my grandmother performs classical music.
Professor: Yes.
Student: 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.
Professor: Really. Well, that’s fascinating. Because she probably had to reinvent her whole musical style.
Student: She did. But jazz was where the money was at that time, at least for her.
Professor: But she eventually went back to classical?
Student: Right. But only recently.
Professor: Ok.
Student: So if I can show how her choices relate to what was happening in the world of music at the time…?
Professor: I think that might work very nicely.
Student: And if I do that, I guess I’ll have to like, interview her.
Professor: Right.
Student: And I guess that would mean…
Professor: You’ll have to rewrite most of your paper.
Student: Ouch!
Professor: Yeah. Would an extra week ease the pain?
Student: Definitely.
Professor: Ok. So are there other musicians in your family?
Student: Yeah. My mother plays piano, too. Not as well as my grandmother, but…
Professor: And you?
Student: 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.
Professor: That’s great! Could I tell the class about your concert?
Student: Um…sure. But…about my paper… what question should I be asking my grandmother?
Professor: You know what, I have a meeting now. Why don’t you come to class a few minutes early tomorrow?
Student: Will do.


TPO22 Lecture 3 (Zoology)
Narrator: Listen to part of a lecture in a zoology class.

Professor: A mass extinction as 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 percent of marine species disappeared.
Well, today we are witnessing a sixth mass extinction, but unlike the others, the current loss of bio-diversity can be traced to human 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, many megafauna began disappearing by the end of the Pleistocene.
So here’s the biologists’ 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 United 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 interactions 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 American 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 cheetahs were still around. That’s what’s meant by evolutionary potential. Importing African cheetahs to the western United States could, in theory, put the pronghorn back onto its… uh, natural evolutionary trajectory according to these biologists.
Another example is the 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 American plants, such as the maclura tree. Many types of maclura used to grow in North American, 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 size of an orange in their 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 ancestors did.
Get the idea? Restoring some of the former balance to the ecosystem? 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 years since the Pleistocene epoch, native species have adapted to the changing environmental there, plants, smaller animals, they have been evolving without megafauna for millennia. Also, animal species that went extinct 11,000 years ago, uh, some are quite different genetically from their modern-day counterparts, like elephants don’t have thick coasts like their mastodon ancestors do when they graze the prairies of the America West during the Ice Age. Granted, the climate today is not as cold as it was in the 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.


TPO22 Lecture 4 (Music History)
Narrator: Listen to part of a lecture in a music history class.

Professor: So, uh, if you are a musician in the United States in the early twentieth century, where could you work?
Student: Same as now, I suppose. In an orchestra, mainly.
Professor: Ok. And where would the orchestra be playing?
Student: Uh, in a concert hall or a dance hall?
Professor: That’s right. And 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.
Student: Really? You mean being a piano player or something? I thought movie theaters would have used recorded music.
Professor: 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 job 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 20,000 jobs for musicians were gone, disappeared at the end of the silent-film era, 20,000. Ok. So from the beginning, music was a big part of film, even at the first…
Student: Excuse me, professor. I think I read somewhere that they used music to drown out the sound of the film projectors?
Professor: 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 film 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 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.
Student: Are you saying there was no music written specifically for a particular movie?
Professor: 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 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.
Student: Ok. But even after that someone still had to play the music for the sound for the sound recordings, the soundtracks.
Professor: Yeah. But think of all the movie theaters there were, most employing about six to eight musicians, some even had full orchestras. But in the 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 orchestra 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 it, 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.

香草鱼UID：3125484

TPO 23:CONVERSATION 1
Narrator: Listen to a conversation between a student and the director of campus activities.

Student: 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.
Director: And when did you summit this request?
Student: Last Wednesday. I followed the instructions very carefully. I am sure it was Wednesday, because know announcements have be submitted three business days ahead of the posting day.
Director: And what's it for?
Student: A reading.
Director: A reading?
Student: Yes. A poetry reading.
Director: Oh, OK. When is it?
Student: 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.
Director: Wow. This person is really coming all the way from France?
Student: Oh, no. He is teaching promising there will be in New York City this year. We were able to sell him on a nice size crowd , felt confident about that. Because the idea by I know how enthusiastic our group is.
Director: And your group ? do you have a name?
Student: 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.
Director: OK. And it is a recognized group? By the university, I mean.
Student: No
Director: OK.
Student: But the French Department is funding this, on the condition that we do all the legwork.
Director: 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.
Student: Not included? Why?
Director: 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...
Student: 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?
Director: 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.
Student: I knew we should have done a poster. But everybody was like, oh, you can just post it online. In any event, thanks for you help. It's something to consider.

TPO23 Lecture l- Archaeology (Antikythera (Mechanism)
Narrator: Listen to part of a lecture in an archaeology class.

Professor: 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. At any rates, 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 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 ? well, 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 mass. 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 reasons 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.


TPO23 Lecture2 - Environmental Science (Earth Budget)
Narrator: Listen to part of a lecture in an environmental science class.

Professor: Basically, a cloud either contributes to the cooling of Earth's surface or to its heating. Earth's 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 are 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 planet.
A surface's albedo is the percentage of incoming solar energy, sunlight, that's reflected off that 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... rainforests also have low albedos. Well, by contrast, deserts and areas covered by ice and snow, these places have high albedos. And clouds, in general, cloud also have high albedos. That means that a large percentage of the solar energy clouds receive is reflected 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.
Student: So which type of clouds cools Earth? And which type heat it?
Professor: Well, high thin clouds contribute to heating while low thick clouds cool Earth. High thin clouds are very transparent to solar radiation, like, uh, clear air. So they mostly transmit incoming solar energy down to Earth. There's not much reflection going at all. At the same time, these clouds trap in some of Earth's heat. Because of the trapped heat, these clouds have an overall heating effect.
Student: Oh. OK. Since low thick clouds are not transparent to radiation...
Professor: Exactly. They block most of the solar energy so it never reaches Earth's surface. They reflect much of it back out into space.
Student: So that's how they contribute to cooling?
Professor: Yep. And as I said earlier, this cooling effect predominates. Now, what if there was a process that could control the type of clouds that form?
Student: Are you talking about controlling the weather?
Professor: Well, I am not sure I would go that far.语气题 But we recently noticed an increase in cloud cover over an area of the ocean waters around Antarctica. An increased area of low thick clouds, the type that reflects a lare portion of 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, dimetho 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 microorganisms near Antarctica really are responsible, perhaps we can accelerate the process somehow.

香草鱼UID：3125484

TPO 23 Conversation 2
Narrator: Listen to a conversation between a student and his English professor.

Professor: Hi, Bob. How is it going? Are you enjoying the Introduction to Literature class?
Bob: Yeah, it's great. Araby, that short story by James Joyce we read last week, it was awesome.
Professor: 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.
Bob: Me too. So why did you pick Araby instead of some other story?
Professor: 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.
Bob: Still, I wish we could read whole novels by Joyce and discussed them in class.
Professor: That's what happens in my Master Writer Class.
Bob: Master Writer Class?
Professor: 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.
Bob: 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?
Professor: 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 in the room.
Bob: 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?
Professor: 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.
Bob: But why do I have to study different styles to understand Joyce's novels?
Professor: 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 you meet there is by studying a variety of authors.
Bob: Oh, OK. So could you suggest a different literature class then?
Professor: 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.
Bob: Sweet. Thanks.



TPO23 Lecture3 Biology (Dolphins)
Narrator: Listen to part of a lecture in a marine biology class.

Professor: 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 does 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 merrily 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 broadcast 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 um, modify the overcome this mismatch in the density of air and water would be ? if you travels through velocity of the sound wave, make it precisely match the speed at which water. And that's exactly what marine biologists have discovered the melon 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.



TPO23 Lecture4 Choreography (Screen Dance)
Narrator: Listen to part of a lecture in a choreography class.

Professor: 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.
Student: 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.
Professor: 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.
Student: But ? um, I have never used a movie camera or edited film before. How will we learn everything we need to know to ? ?
Professor: 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.
Student: Could you talk some more about the film - making techniques, you know, the ones that work best forscreen dances?
Professor: 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 layered in the editing room. The fire was added to the background.
Student: 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?
Professor: 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 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 ? u h, 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.

香草鱼UID：3125484

Conversation l一Student & Clerk in the Bookstore
Narrator: Listen to a conversation between a student and a clerk in the bookstore.

Student: Hi. Can you tell me where to find New Kind of Science? By, uh, by Stephen Wolfram.
Clerk: OK
Student: ...uh, I couldn't find it
Clerk: OK. Let me look it up on the computer for you. Who would you say the author was?
Student: It's a Stephen Wolfram.
Clerk: OK. Let's see... Hmm... no, it's not coming up. Hmm..,. I am not seeing it
Student: Um...hmm.
Clerk: This is for a course here at the university, right?
Student: Yeah, It's assigned reading for a class I am taking.
Clerk: It's for the semester, right? You are not buying it in advance for next year or anything.
Student: No, no. It's for a class I am taking now.
Clerk: Hmm...
Student: 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...
Clerk: 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 that 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.
Student: Well, uh, 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.
Clerk: 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, no. I am not seeing it. I am sorry. We just don't seem to carry it.
Student: Uh-huh.
Clerk: 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
Student: Um...OK. It's professor Kayne.
Clerk: K-A-N-E?
Student: No. It's professor Kayne, K-A-Y-N-E. He's in the computer science department.
Clerk: Oh. It's for a computer science course, is it?
Student: Yeah.
Clerk: Well, that must be it. Computer science books are sold across the street in the computer bookstore.
Student: Are there signs up anywhere?
Clerk: I don't know.
Student: Maybe they should put some up. It could have save us both some time.
Clerk: 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?
Student: OK. Thanks a lot. Bye
Clerk: Bye

Lecture l-Biology (Crocodile Vocalization)
Narrator: Listen to part of a lecture in a Biology class.

Professor: 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 catched 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.
Student: Excuse me. But, um... does all that crying defeat the purpose? I mean, doesn't it attract more predators?
Professor: Hmm...good question. I guess, well, 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, 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.

Lecture2-Art History (Modern Dance)
Narrator: Listen to part of a lecture in a dance history class.

Professor: 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.
Student: Um... what made modern dance so radical?
Professor: 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 steep 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 composers, but avoiding set audiences, for the most part, and other European cities, dancing to the music of classical movements and steps, no two performances were alike. And 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?
Student: Yeah. What did Duncan have against ballet? I mean, she studied it as a child.
Professor: As a youngster, she might have found it too restrictive, uh, not creative enough. I think that feeling is exemplied 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 publically 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.

香草鱼UID：3125484

Conversation 2一Student & Geography Professor
Narrator: Listen to a conversation between a student and his geography professor.

Student: Hi. Professor Brown.
Professor: Hi. Paul. What can I do for you?
Student: 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.
Professor: Everything we've done all term.
Student: 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.
Professor: Well, uh, have you been to the tutoring center?
Student: No, not for geography anyway. Isn't that just for when you need help with writing, like an essay or a research paper.
Professor: Oh, no. you can get tutoring in a lot of subjects. Some graduate students from this department tutor there.
Student: 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.
Professor: 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?
Student: 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.
Professor: That's it. Basically. Um... so exactly what is it you don't understand?
Student: OK. I guess what I am really confused about is how the topography of the land, the mountains and valleys and stuff, affects precipitation.
Professor: 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 have cold air flowing over it, mostly in the Northern Hemisphere
Student: Like the great lakes in the United States?
Professor: Yeah. 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.
Student: So it starts to rise, right?
Professor: 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.
Student: And then it snows because as the air rises, it cools off and loses its capacity to hold water vapor.
Professor: That's right.
Student: OK. Thanks. Any chance you'll have this question on the final?
Professor: I don't know yet. But you seem to have a handle on it.

Lecture3-Archaeology (Megafauna in North America)
Narrator: Listen to part of a lecture in an archaeology class.

Professor: Between 11,000 and 10,000 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 sloths, the list goes on. By about 10,000 B.C.E., all those giant creatures, the Metgauna of North America were gone. We don't 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 coexisted 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 evidences. Mammoth bones have also been found at some other Clovis sites.
But then at other Clovis sites, there's also a lot of evidence that the Clovis people mostly gather plants and hunted small game, like rabbits and wild turkeys. Also there are several places in North America where you have natural accumulations of mammoth bones that look very similar to the accumulations at the Clovis site, except there's 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 thirteen mammoths in southern California also died of natural causes, and that the Clovis people simply took advantage of the situation. Um...OK. That's the hunting theory.
Now let's look at another theory, uh, an alternative to the hunting theory, the climate change theory. At around 11,500 B.C.E.，the world was coming out of an Ice Age .And with  that  came  increased seasonality, that is, the summers became warmer, and the winters actually became colder. These 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 horizontal bands of plant communities. In the far north, it is tundra, which gives way to 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, in any given area, there was less plant diversity. And as a result, uh, so the theory goes, the Ice Age animals that depended on plant diversity couldn't survive. And the great 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 archaeologist 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. Say, for example, there is a drought for a couple of decades, or hunters are killing or five percent of the population, and so on.
One thing he found was that humans didn't necessarily have to kill these animals in great numbers in order to nudge them toward 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 herd, 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 mammoths 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.


Lecture4-Astronomy (Shield Volcanoes on Venus)
Narrator: Listen to part of a lecture in an astronomy class.

Professor: 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, but we have learned a lot about it in the past several years.
First of all, let me talk about how we have been able to get past those clouds. First, there were Soviet modules2 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?
Student: Well, I remember reading that there's not really a lot going on, that the surface of Venus is just flat and smooth in a lot of places.
Professor:  Yeah, 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, meteo 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 is 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 warrior's 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 a result of tectonic plate movement. Remember tectonic plates?
Underneath the Earth's crust, there are a number of 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 where we get most of Earth's volcanoes
On Venus, however, volcanoes are not clustered in discrete zones like they are on Earth. Instead, they are more or less randomly scattered over Venus's surface. Well, that's significant. Venus has mostly shield volcanoes, and they are randomly scattered, that indicates that Venus does not have moving tectonic plates, and that's a big difference compared to Earth. Here on Earth, moving tectonic plates are a major geological element, just crucial for the whole surface dynamic, right?
So why doesn't Venus have them? Well, there are a few theories. 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. Uh, Venus has no surface water.
Student: Wait a second. Did you say we have shield volcanoes on Earth? Can you give an example?
Professor: Sure. The volcanoes in the Hawaii islands, in the Pacific Ocean are shield volcanoes. They are formed over a hot spot of magma. So while on Earth we have several types of volcanoes, on Venus there's mostly the one type. Uh, Eric?
Student: Are the volcanoes on Venus still active?
Professor: Well, that's an interesting question. There is still some discussion on that point. But here's what we do now. First, the level of sulfur dioxide gas above Venus's clouds shows large and very frequent fluctuations. It is 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 volcanoes erupt on Earth. So this too suggests ongoing volcanic activity. But although this is intriguing evidence, no one's actually observed a Venus volcano erupting yet, so we can't be positive.

dandelioaUID：3324720

谢谢LZ的细心分析~~~