题目内容
Pushbike Peril
Low speed bicycle crashes can badly injure or even kill children if they fall onto the ends of the handlebars(车把) so a team of engineers is redesigning the humble handlebar in a bid to make it safer.
Kristy Arbogast, a bioengineer at the Children's Hospital of Philadelphia in Pennsylvania, began the project with her colleagues after a study of serious abdominal(腹部的) injuries in children in the past 30 years showed that more than a third were caused by bicycle accidents. "The task was to identify how the injuries occurred and come up with some countermeasures(对策)." she says.
By interviewing the children and their parents, Arbogast and her team were able to reconstruct(重建；重构) many of the accidents and identified a common mechanism responsible for serious injures. They discovered that most occur when children hit an obstacle at a slow speed, causing them to topple over. To maintain their balance they turn the handlebars through 90 degrees, but their momentum (冲力) forces them into the end of the handlebars. The bike then falls over and the other end of the handlebars hits the ground, ramming it into their abdomen.
The solution the group came up with is a handgrip(握柄) fitted with a spring and damping(制动的；减速的，缓冲的) system. The spring absorbs up to 50 per cent of the forces transmitted through the handlebars in an impact. The group hopes to commercialize(使商品化) the device, which should add only a few dollars to the cost of a bike. "But our task has been one of education because up until now, bicycle manufacturer were unaware of the problem. " says Arbogast.
The team has also approached the US Consumer Product Safety Commission to try to persuade manufacturers to adopt the new design. A decision is expected later this year.
According to the passage, some engineers are trying to improve the handlebars because
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James R. Ehleringer tried to find out
Which of the following is closest in meaning to the title？
Which of the following statements is meant by the writer？
Hair Detectives
Scientists have found a way to use hair to figure out where a person is from and where that person has been. The finding could help solve crimes, among other useful applications.
Water is central to the new technique. Our bodies break water down into its parts: hydrogen(氢)and oxygen. Atoms (原子) of these two elements end up in our tissues and hair.
But not all water is the same. Hydrogen and oxygen atoms can vary in how much they weigh. Different forms of a single element are called isotopes(同位素). And depending on where you live, tap water contains unique proportions of the heavier and lighter isotopes of hydrogen and oxygen.
Might hair record these watery quirks(古怪举动；怪僻). That's what James R. Ehleringer, an environmental scientist at the University of Utah in Salt Lake City, wondered.
To find out, he and his colleagues collected hair from barbers and hair stylists(发型师)in 65 cities in 18 states across the United States. The researchers assumed that the hair they collected came from people who lived in the area.
Even though people drink a lot of bottled water these days, the scientists found that hair overwhelmingly(压倒性地) reflected the concentrations of hydrogen and oxygen isotopes in local tap water. That's probably because people usually cook their food in the local water. What's more, most of the other liquids people drink including milk and soft drinks contain large amounts of water that also come from sources within their region.
Scientists already knew how the composition of water varies throughout the country. Ehleringer and colleagues combined that information with their results to predict the composition of hair in people from different regions. One hair sample used in Ehleringer's study came from a man who had recently moved from Beijing, China, to Salt Lake City. As his hair grew, it reflected his change in location.
The new technique can't point to exactly where a person is from, because similar types of water appear in different regions that span a broad area. But authorities can now use the information to analyze hair samples from criminals or crime victims and narrow their search for clues(线索).
What does the writer say about tap water？ Which of the following is NOT correct？
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