题目内容
Winged robot learns to fly
Learning how to fly took nature millions of years of trial and error-but a winged robot has cracked it in only a flew hours，using the same evolutionary principles．
Krister Wolff and Peter N0rdin of Chalmers University of Technology（CUT） in G0thenburg，Sweden，built a winged robot and set about testing whether it could by itself， without any programmed（预先设定好的）data 0n what napping is or how to d0 it．
To begin with，the robot just twitched and jerked（猛抽）erratically（不稳定地）．But gradually，it made movements that gain height． After it cheated—simply standing on its wing tips was one early short cut． After three hours，however，the robot abandoned such methods in favor 0f a more effective flapping technique，where it rotated its wings through 90 degrees and raised them before twisting them back to the horizontal and pushing down．
“This tells us that this kind of evolution is capable of coming up with flying motion，”says Peter
Bentley，who works on evolutionary computing at University College London． But while the robot had worked out how best to produce lift，it was not about to take off． “There’s 0nlv s0 mach that evolution can do， " Bentley says． “This thing is never going to by because the motors will never have the strength t0 do it，”he says． The robots had metre-long wings made from balsa wood and covered with a light plastic film．
Small motors on the robot let it move its wings forwards 0r backwards，up or down 0r twist them in either direction．
The team attached the robot to two vertical rods，so it could slide up and down． At the start of a test，the robot was suspended by an elastic band． A movement detector measured how much lift．if any，the robot produced for any given movement．
A computer program fled the robot random instructions， at the race of 20 per second． to test its flapping abilities． Each instruction told the robot either to do nothing or to move the wings slightly in the various directions．
Feedback from the movement detector let the program work out which sets of instructions were best at producing lift． The most successful ones were paired up and “offspring" sets 0f instructions were generated by swapping（交换）instructions randomly between successful pairs．These next-generation instructions were then sent to the robot and evaluated before breeding a new generation， and the process was repeated．
第 26 题 Which of the following is NOT true of what is mentioned about the winged robot in the second paragraph？
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Two People, Two Paths
You must be familiar with the situation: Dad's driving, Mum's telling him where to go.He's sure that they need to turn left. But she says it's not for another two blocks. Who has the better sense of direction Men or women.
They both do, a new study says, but in different ways.
Men and women,- Canadian researchers have found, have different methods of finding their way. Men look quickly at landmarks （地标） and head off in what they think is the right direction. Women, however, try to picture the whole route in detail and then follow the path in their head.
"Women tend to be more detailed," said Edward Cornell, who led the study, "while men tend to be a little bit faster and...a little bit more intuitive （直觉感知的）."
In fact, said Cornell, "sense of direction" isn't one skill but two.
The first is the "survey method". This is when you see an area from above, such as a printed map. You can see, for example, where the hospital is, where the church is and that the supermarket is on its right.
The second skill is the "route method". This is when you use a series of directions. You start from the hospital, then turn left, turn right, go uphill －and then you see the supermarket.
Men are more likely to use the survey method while women are more likely to use one route and follow directions.
Both work, and neither is better.
Some scientists insist that these different skills have a long history. They argue it is because of the difference in traditional roles.
In ancient times, young men often went far away with the older men to fish or hunt.The trip took hours or days and covered unfamiliar places. The only way to know where you were was to use the survey method to remember landmarks -- the mountains, the lakes and so on.
The women, on the other hand, took young girls out to find fruits and plants. These activities were much closer to home but required learning well-used paths. So, women's sense of space was based on learning certain routes.
第 31 题 When finding his way, Dad tends to rely on.
Psychologists find the list a good place where they can study human behavior. because________．
A．knew B．concluded C．saw D．thought
Eat More, Weigh Less, Live Longer
Clever genetic detective work may have found out the reason why a near-starvation diet prolongs the life of many animals.
Ronald Kahn at Harvard Medical School in Boston, US, and his colleagues have been able to extend the lifespan （寿命） of mice by 18 per cent by blocking the rodent's （啮齿动物） increase of fat in specific cells. This suggests that thinness--and not necessarily diet--promotes long life in "calorie （热量卡） restricted" animals.
"It's very cool work," says aging researcher Cynthia Kenyon of the University of California, San Francisco. "These mice eat all they want, lose weight and live longer. It's like heaven."
Calorie restriction dramatically extends the lifespan of organisms as different as worms and rodents. Whether this works in humans is still unknown, partly because few people are willing to submit to such a strict diet.
But many researchers hope they will be able to trigger the same effect with a drug once they understand how less food leads to a longer life. One theory is that eating less reduces the increase of harmful things that can damage cells. But Kahn's team wondered whether the animals simply benefit by becoming thin.
To find out, they used biology tricks to disrupt the insulin （胰岛素） receptor （受体） gene in lab mice--but only in their fat cells. "Since insulin is needed to help fat cells store fat, these animals were protected against becoming fat," explains Kahn.
This slight genetic change in a single tissue had dramatic effects. By three months of age, Kahn's modified mice had up to 70 per cent less body fat than normal control mice, despite the fact that they ate 55 per cent more food per gram of body weight.
In addition, their lifespan increased. The average control mouse lived 753 days, while the thin rodents averaged a lifespan of 887 days. After three years, all the control mice had died, but one-quarter of the modified rodents were still alive.
"That they get these effects by just manipulating the fat cells is controversial," says Leonard Guarente of the Massachusetts Institute of Technology, who studies calorie restriction and aging.
But Guarente says Kahn has yet to prove that the same effect is responsible for increased lifespan in calorie-restricted animals. "It might be the same effect or there might be two routes to long life," he points out, "and that would be very interesting."
第 41 题 Ronald Kahn and his colleagues can make mice live longer by.
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