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Here"s yet another to lose weight. Heavier people are more likely to be killed or seriously injured in car accidents than lighter people. That could mean car designers will have to build in new safety features to compensate for the extra hazards facing overweight passengers. In the US, car manufacturers have already had to redesign air bags so they inflate to lower pressures making them less of a danger to smaller women and children. But no one yet knows what it is that puts overweight passengers at extra risk. A study carried out in Seattle, Washington, looked at more than 26,000 people who had been involved in car crashes, and found that heavier people were at far more risk. People weighing between 100 and 119 kilograms are almost two-and-a-half times as likely to die in a crash as people weighing less than 60 kilograms. And importantly, the same trend held up when the researchers looked at body mass index(BMI)— a measure that takes height as well as weight into account. Someone 1.8 meters tall weighing 126 kilograms would have a BMI of 39, but so would a person 1.5 meters tall weighing 88 kilograms. People are said to be obese if their BMI is 30 or over. The study found that people with a BMI of 35 to 39 are over twice as likely to die in a crash compared with people with BMIs of about 20. It"s not just total weight, but obesity that"s dangerous. While they do not yet know why this is the case, the evidence is worth pursuing, says Charles Mock, a surgeon and epidemiologist at the Harborview Injury Prevention and Research Center in Seattle, who led the research team. He thinks one answer may be for safety authorities to use — heavier crash-test dummies when certifying cars are safe to drive. Crash tests normally use dummies that represent standard-sized males weighing about 78 kilograms. Recently, smaller crash-test dummies have also been used to represent children inside crashing cars. But larger and heavier dummies aren"t used, the US National Highway Traffic Safety Administration in Washington, D.C. told New Scientist. The reasons for the higher injury and death rates are far from clear. Mock speculates that car interiors might not be suitably designed for heavy people. Or obese people, with health problems such as high blood pressure or diabetes, could be finding it tougher to recover from injury. When they redesigned air bags to hold less pressure, the American car manufactures______.
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Scientists used to believe adult brains did not grow any new neurons, but it has emerged that new neurons can sprout in the brains of adult rats, birds and even humans. Understanding the process could be important, for finding ways to treat diseases such as Alzheimer"s in which neurons are destroyed. Most neurons sprouting in adulthood seem to be in the hippocampus, a structure involved in learning and memory. But they rarely survive more than a few weeks. "We thought they were possibly dying because they were deprived of some sort of input," says Elizabeth Gould, a neuroscientist at Princeton. Because of the location, Gould and her colleagues suspect that learning itself might bolster the new neurons" survival, and that only tasks involving the hippocampus would do the trick. To test this, they injected adult male rats with a substance that labeled newborn neurons so that they could be tracked. Later, they gave some of the rats standard tasks. One involved using visual and spatial cues, such as posters on a well, to learn to find a platform hidden under murky water. In another, the rats learnt to associate a noise with a tiny shock half a second later. Both these tasks use the hippocampus — if this structure is damaged, rats can"t do them. Meanwhile, the researchers gave other rats similar tasks that did not require the hippocampus finding a platform that was easily visible in water, for instance. Other members of the control group simply paddled in a tub of water or listened to noises. The team reported in Nature Neuroscience that the animals given the tasks that activate the hippocampus kept twice as many of their new neurons alive as the others. "Learning opportunities increase the number of neurons," says Gould. But Fred Gage and his colleagues at the Salk Institute for Biological Studies in La Jolla, California, dispute this. In the same issue of Nature Neuroscience, they reported that similar water maze experiments on mice did not help new neurons survive. Gould thinks the difference arose because the groups labeled new neurons at different times. She gave the animals tasks two weeks after the neurons were labeled. When the new cells would normally be dying, she thinks the Salk group put their mice to work too early for new neurons to benefit. "By the time the cells were degenerating, the animals were not learning anything." she says. Which of the following can clearly tell the two groups of rats from each other in the test
Whenever people go and live in another country they have new experiences and new feelings. They experience culture shock. Many people have a(n) 【C1】______about culture shock they think that it"s just a feeling of sadness and homesickness when a person is in a new country. But this isn"t really true. Culture shock is a completely natural【C2】______. and everybody goes【C3】______it in a new culture. There are four stages, or steps, in culture shock. When people first arrive in a new country they"re usually excited and【C4】______Everything is interesting. They notice that a lot of things are【C5】______their own culture and this surprises them and makes them happy. This is Stage One In Stage Two people notice how different the new culture is from their own culture. They become confused It seems difficult to do even very simple things. They feel【C6】______They spend a lot of time【C7】______or with other people from their own country. They think "My problems are all because I"m living in this country" Then in Stage Three they begin to understand the new culture better They begin to like some new customs. They【C8】______some people in the new country. They"re【C9】______comfortable and relaxed. In Stage Four they feel very comfortable. They have good friends in the new culture. They understand the new customs. Some customs are similar to their culture and some are different but that"s OK. They can【C10】______it. 【C3】
Whenever people go and live in another country they have new experiences and new feelings. They experience culture shock. Many people have a(n) 【C1】______about culture shock they think that it"s just a feeling of sadness and homesickness when a person is in a new country. But this isn"t really true. Culture shock is a completely natural【C2】______. and everybody goes【C3】______it in a new culture. There are four stages, or steps, in culture shock. When people first arrive in a new country they"re usually excited and【C4】______Everything is interesting. They notice that a lot of things are【C5】______their own culture and this surprises them and makes them happy. This is Stage One In Stage Two people notice how different the new culture is from their own culture. They become confused It seems difficult to do even very simple things. They feel【C6】______They spend a lot of time【C7】______or with other people from their own country. They think "My problems are all because I"m living in this country" Then in Stage Three they begin to understand the new culture better They begin to like some new customs. They【C8】______some people in the new country. They"re【C9】______comfortable and relaxed. In Stage Four they feel very comfortable. They have good friends in the new culture. They understand the new customs. Some customs are similar to their culture and some are different but that"s OK. They can【C10】______it. 【C2】
Scientists used to believe adult brains did not grow any new neurons, but it has emerged that new neurons can sprout in the brains of adult rats, birds and even humans. Understanding the process could be important, for finding ways to treat diseases such as Alzheimer"s in which neurons are destroyed. Most neurons sprouting in adulthood seem to be in the hippocampus, a structure involved in learning and memory. But they rarely survive more than a few weeks. "We thought they were possibly dying because they were deprived of some sort of input," says Elizabeth Gould, a neuroscientist at Princeton. Because of the location, Gould and her colleagues suspect that learning itself might bolster the new neurons" survival, and that only tasks involving the hippocampus would do the trick. To test this, they injected adult male rats with a substance that labeled newborn neurons so that they could be tracked. Later, they gave some of the rats standard tasks. One involved using visual and spatial cues, such as posters on a well, to learn to find a platform hidden under murky water. In another, the rats learnt to associate a noise with a tiny shock half a second later. Both these tasks use the hippocampus — if this structure is damaged, rats can"t do them. Meanwhile, the researchers gave other rats similar tasks that did not require the hippocampus finding a platform that was easily visible in water, for instance. Other members of the control group simply paddled in a tub of water or listened to noises. The team reported in Nature Neuroscience that the animals given the tasks that activate the hippocampus kept twice as many of their new neurons alive as the others. "Learning opportunities increase the number of neurons," says Gould. But Fred Gage and his colleagues at the Salk Institute for Biological Studies in La Jolla, California, dispute this. In the same issue of Nature Neuroscience, they reported that similar water maze experiments on mice did not help new neurons survive. Gould thinks the difference arose because the groups labeled new neurons at different times. She gave the animals tasks two weeks after the neurons were labeled. When the new cells would normally be dying, she thinks the Salk group put their mice to work too early for new neurons to benefit. "By the time the cells were degenerating, the animals were not learning anything." she says. Not until recently did scientists find out that ______.
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