深大研究生聽(tīng)力Lectures.docx

Tonight Im going to talk to you about that remarkable continent Antarctica remote, hostile and at present uninhabited on a permanent basis. For early explorers, it was the ultimate survival contest; for researchers like me, it remains a place of great intellectual challenge; while for the modern tourist, its simply a wilderness of great beauty.First, some facts and figures. Antarctica is a place of extremes the highest, coldest and windiest continent and over fifty-eight times the size of the UK. The ice-cap contains almost 70 of the worlds fresh water and 90 of its ice, but with very low snowfall, most of the continent technically falls unbelievably into the category of desert! huge icebergs break off the continent each year, while in winter half the surrounding ocean freezes over, which means its size almost doubles.Research and exploration has been going on in Antarctica for more than two hundred years, and has involved scientists from many different countries, who work together on research stations. Here science and technical support have been integrated in a very cost-effective way our Antarctic research programme has several summers only stations and two all-year-round ones; I was based on one of the all-year-round ones.The research stations are really self-contained communities of about twenty people. Theres living and working space, a kitchen with a huge food store, a small hospital and a well-equipped gym to ensure everyone keeps fit in their spare time. The station generates its own electricity and communicates with the outside world using a satellite link.Our station Zero One had some special features. It wasnt built on land but on an ice-shelf, hundreds of meters thick. Supplies were brought to us on large sledges from a ship fifteen kilometers away at the ice edge.Living in the Antarctic hasnt always been so comfortable. Snow build-ups caused enormous problems for four previous stations on the same site, which were buried and finally crushed by the weight. Fortunately no-one was hurt, but these buildings became a huge challenge to architects who finally came up with a remarkable solution the buildings are placed on platforms which can be raised above the changing snow level on legs which are extendable.Food is one of the most important aspects of survival in a polar climate. People living there need to obtain a lot more energy from their food, both to keep warm and to undertake heavy physical work. Maybe you know that an adult in the UK will probably need about 1,700 kilocalories a day on average; someone in Antarctica will need about 3,500 just over double! This energy is provided by foods which are high in carbohydrate and fat.Rations for fieldwork present and additional problem. They need to provide maximum energy, but they must also be compact and light for easy transport. Special boxes are prepared, each containing enough food for one person for twenty days. You may be familiar with coffee processed by freeze-drying, which preserves the quality of the food product while making a large saving in weight well, this type of presentation is ideal in our situation. It wasnt available to earlier polar explorers, whose diet was commonly insufficient for their health.I think that being at the cutting edge of science has a special appeal for everyone working in Antarctica, in whatever capacity. As a marine biologist, my own research was fascinating; but its perhaps climate change research that is the most crucial field of study.Within this general field, surveying changes in the volume and stability of the ice-cap is vital, since these may have profound effects on world sea levels and on ocean currents. A second important area is monitoring the size of the hole in the ozone layer above Antarctica, since this is an indicator of global ultra violet radiation levels. Thirdly, bubbles in the ice-sheet itself provide an index of pollution because frozen inside them are samples of previous atmospheres over the past 500,000 years, and these provide us with evidence for the effects of such human activities as agriculture and industry.There are an increasing number of opportunities for young people to work for a period in Antarctica not only as research assistants in projects like mine, but also in a wide range of junior administrative and technical positions including vacancies for map-makers. I hope that the insights Ive provided will encourage you to take up these opportunities in this fascinating continent.The history of moving picturesMany believe that the story first began in America in 1877, when two friends were arguing over whether a horse ever had all 4 feet or hooves off the ground when they galloped. To settle the bet, a photographer was asked to photograph a horse galloping and the bet was settled because you could see that all the hooves were off the ground in some of the photos. What was even more interesting was that if the photos were shown in quick succession the horse looked like it was running- in other words moving pictures.The person who became interested in taking the moving pictures to its next step was the famous American inventor Thomas Edison. Actually, he didnt do the work himself but rather asked a young Scotsman in his employ to design a system, which he did. Now this young fellow was clever because the first thing he did was study other systems- primitive as they were of moving pictures and then put all the existing technologies together to make the first entire motion picture system. He designed a camera, a projection device and the film. The system was first shown in New York in 1894 and was really very popular. Apparently people lined up around the block to see the wonderful new invention. There were, however, a couple of problems with the system. The camera weighed over 200 kilograms and only one person at a time could see the film. Well, now news of the new system in America travelled fast and a number of rival European systems started to appear once people had heard about it. The single problem with all the systems was they couldnt really project the film onto a screen- you know, so more than one person could see it. Then in 1895, three systems were all developed, more or less at the same time and independently of each other. I guess the most famous of these was by the Lumiere Brothers from France, and they called their system the cinematographe which of course is where the word cinema comes from. There were also 2 brothers in Germany who developed a successful system and they called it bioskop. Well now, once the problem of projection had been solved, the next challenge for the inventors was to make the films longer and more interesting. A continuing problem at that time was that the films had a tendency to break when they were being played-a problem which was caused by the tension between the 2 wheels ,or reels as they are called,which hold the film. Now this problem was solved by 2 American brothers. They developed the “Lantham Loop”, which was the simple addition of a third reel between the 2 main reels and this took all the tension away with the result that the film stopped snapping.So now there was a real possibility of having films of more than 2 or 3 minutes, and this led to the making of The Great Train Robbery- the very first movie made. It only lasts the 11 minutes but was an absolute sensation, and there were cases of people watching the movie and actually fainting when the character fired a gun at the camera! Almost overnight movies became a craze, and by 1905 people in America were lining up to see movies in store theatres, as they were called then.I guess the next big step in terms of development of technology was to have people actually talking on the film, and first step towards this was in 1926 when sound effects were first used on the film. It wasnt until the following year however the first talkie, as they were called then, was made. This film featured actors speaking only during parts of the film and was called The Jazz Singer, and it wasnt until the 1928 that the first all-talking film was produced, and this was The Lights of New York. Unfortunately, the sound on this early film was not very good and I believe they put subtitles on the film.-that is, they printed the dialogue along the bottom of the film to compensate for this poor sound quality. Now, with the addition of sound, moving pictures became far more difficult to makeToday, Im going to talk about risk ,or how people think about risk. First, Ill discuss two concepts. Perceived risk versus actual risk. Then Ill talk about why we worry about some risks more than others.There are two important turns you need understand before we begin , perceived risk and actual risk . Perceived risk is the way a person thinks about risk. Perceived risk is now risky a person thinks the activity is . Ah, this is supposed to actual risk which is the true risk . The risk something if you actual look at how many people are hurt or injured by activity . So lets begin with example. And example love perceived risk versus actual risk . Lets compare two ways to travel . Flying versus driving a car. Many people drive a car each day , but they dont worry about very much . They know that there is risk of accident , but most people will not say they are afraid of driving. They fell that the risk is low , so the perceived risk of is low. On the other hand , many people worry about flying. They are afraid that airplane will have an accident and crash. They feel that risk of flying is higher than risk if driving. The perceived risk of flying is high.In fact , the flying is forty times safer than driving a car , but our perception is that flying is more dangerous. Why? Why do we worry about some risks more than others? Well, it turns out that we perceived risk differently in special certain standards. Some factors make person feel negativity is less risky; some make us feel negativity is more risky. But the certain risk is really changing our perception.There are three factors that make us feel negativity less risky. The first factor is control, whether the risk negativity we control as supposed as one we dont control. In circumstance, well have more control we feel there is less risky. For example, lets look at driving a car versus flying airplane. When we drive, we control the car, we design where to drive and how fast to go. Therefore, we feel that driving is less risky. However, when we fly an airplane, we do not control is. Someone else is flying it, so we feel it is more risky.The second factor is whether the risk is natural versus unnatural. When the risk is natural, we feel that there is less risk. For example, we can power plants are unnatural, that is created by people, so we feel that they have certificated risk. The sand is natural, so we feel that is two risks. However, many more people get cancer each year from the sand than form nuclear power, so being in the sand has higher actual risk, but we feel that being in the sad is less risky because it is natural. Ah, finally. The third factor is how coming the activity is, that is whether the risk is part of everyday activity in a contrast to an usual invent. When the risk is in everyday activity, we feel there is less risky. For example, lets look our feelings about accidents at home versus airplane accidents are usual, but they do sometimes occur. When and where has an accident, is reported news and gets a lot of attention, so people worry about these accidents more. However , accidents at home occur all the time , each day , many people are injured even killed do everyday things like walking down the stairs ,but we dont worry about these everyday risks much . So you can see from these examples that peoples perceived risk is very different from actual risk, and you can understand some other reasons what.SECTION 4 Today we continue our series on ecology and conservation with a look at a particularly endangered member of the black bear family. One in ten black bears is actually born with a white coat which is the result of a special gene that surfaces in a few. Local people have named it the spirit bear. And according to the legends of these communities its snowy fur brings with it a special power. Because of this, it has always been highly regarded by them -so much that they do not speak of seeing it to anyone else. It is their way of protecting it when strangers visit the area.The white bears habitat is quite interesting. The bears strong relationship with the old- growth rainforest is a complex one. The white bear relies on the huge centuries-old trees in the forest in many ways. For example, the old-growth trees have extremely long roots that help prevent erosion of the soil along the banks of the many fish streams. Keeping these banks intact is important because these streams are home to salmon, which are the bears main food source. In return, the bears feeding habits nurture the forest. As the bears eat the salmon, they discard the skin and bones in great amounts on the forest floor, which provide vital nutrients. These produce lush vegetation that sustains thousands of other types of life forms, from birds to insects and more. Today the spirit bear lives off the coast of the province of British Columbia on a few islands. There is great concern for their survival since it is estimated that less than two hundred of these white bears remain. The best way to protect them is to make every effort to preserve the delicate balance of their forest environment - in other words, their ecosystem. The greatest threat to the bears existence is the loss of its habitat. Over many years, logging companies have stripped the land by cutting down a large number of trees. In addition, they have built roads which have fractured the areas where the bear usually feeds and many hibernation sites have also been lost. The logging of the trees along the streams has damaged the places where the bears fish. To make matters worse, the number of salmon in those streams is declining because there is no legal limit on fishing at the moment. All these influences have a negative impact on the spirit bears very existence, which is made all the more fragile by the fact that reproduction among these bears has always been disappointingly low.And so, whats the situation going forward? Community organizations, environmental groups and the British Columbia government are now working together on the problem. The government is now requiring logging companies to adopt a better logging method, which is a positive step. However, these measures alone may not be sufficient to ensure a healthy population of the spirit bear in the future. Other steps also need to be taken. While it is important to maintain the spirit bears habitat, there also needs to be more emphasis on its expansion. The move is justified as it will also create space for other bears that are losing their homes. Today were going to look at an important area of science, namely nanotechnology. So what is it? Nano means tiny, so its science and engineering on the scale of atoms and molecules. The idea is that by controlling and rearranging atoms, you can literally create anything. However, as well see, the science of the small has some big implications affecting us in many ways.Theres no doubt that nanotechnology promises so much for civilisation. However, all new technologies have their teething problems. And with nanotechnology, society often gets the wrong idea about its capabilities.Numerous science-fiction books and movies have raised peoples fears about nanotechnology - with scenarios such as inserting little nano-robots into your body that monitor everything you do without you realising it, or self-replicating nano-robots that eventually take over the world. So how do we safeguard such a potentially powerful technology? Some scientists recommend that nano-particles be treated as new chemicals with separate safety tests and clear labelling.They believe that greater care should also be taken with nano-particles in laboratories and factories. Others have called for a withdrawal of new nano products such as cosmetics and a temporary halt to many kinds of nanotech research.But as far as lm concerned theres a need to plough ahead with the discoveries and applications of nanotechnology.I really believe that most scientists would welcome a way to guard against unethical uses of such technology. We cant go around thinking that all innovation is bad, all advancement is bad. As with the debate about any new technology, it is how you use it thats important. So lets look at some of its possible uses.Thanks to nanotechnology, there could be a major breakthrough in the field of transportation with the production of more durable metals.These could be virtually unbreakable, lighter and much more pliable leading to planes that are 50 times lighter than at present. Those same improved capabilities will dramatically reduce the cost of travelling into space making it more accessible to ordinary people and opening up a totally new holiday destination.In terms of technology, the computer industry will be able to shrink computer parts down to minute sizes. We need nanotechnolog