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This text is mainly about__________． 查看材料
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The Diminishing Scientific Leadership of the U, S.
With the rapid globalization of science itself (more than 40 percent of scientific Ph.D. students trained in the United States are now foreign nationals, roughly half of whom return to their countries of origin ) , the once undisputed U.S.scientific lead, whether relevant to product lead or not, is diminishing.
The competition of foreign students for positions in U.S.graduate schools has also contributed to making scientific training relatively unattractive to U.S.students, because the rapidly increasing supply of students has diminished the relative rewards of this career path. For the best and brightest from low-income countries, a position as a research assistant in the United States is attractive, whereas the best and brightest U.S.students might now see better options in other fields. Science and engineering careers, to the extent that they are opening up to foreign competition (whether imported or available through better communication ) , also seem to be becoming relatively less attractive to U.S. students.
With respect to the role of universities in the innovation process the speculative boom of the 1990s(which, among other things, made it possible to convert scientific findings into cash rather quickly ) was largely unexpected.The boom brought universities and their faculties into much closer contact with private markets as they tried to gain as much of the economic dividends from their discoveries as possible. For a while,the path between discoveries in basic science and new flows of hard cash was considerably shortened. But during the next few decades, this path will likely revert toward its more traditional length and reestablish in a healthy way, the more traditional (and more independent ) relationship between the basic research done at universities and those entities that translate ideas into products and services.
In the intervening years, another new force also greatly facilitated globalization: the rapid growth of the Internet and cheap wide-bandwidth international communication. Today, complex design activities can take place in locations quite removed from manufacturing, other business functions and the consumer. Indeed, there is now ample opportunity for real-time communication between business functions that are quite independent of their specific locations. For example, software are development, with all its changes and complications, can to a considerable extent be done overseas for a U.S.customer.Foreign call centers can respond instantly to questions from thousands of miles away.The result is that low-wage workers in the Far East and in some other countries are coming into even more direct competition with a much wider spectrum of U.S. labor: unskilled in the case of call centers; more highly skilled in the case of programmers.
The rapid globalization of science__________. 查看材料
Which of the following is right for alpha particles？ 查看材料
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Alpha Particle
From decaying radon （氡） atoms can destroy the living cells they strike and increase the likelihood that those cells will later become cancerous.Researchers have now directly demonstrated that neighboring cells not suffering direct hits can be harmed， too. They"ve also taken a step toward showing how this type of radiation，called alpha particles， indirectly hurts those bystanders.
Radon derives from the decay of uranium （铀） and seeps naturally into the air from the ground.lt"s the primary environmental source of alpha particles， which contribute to cancer risk by causing aberrations （失常）in DNA.Alpha particles from inhaled radon are second only to smoking as a cause of lung cancer.
Because a person"s exposure to alpha particles typically is low， researchers have had to estimate public health threats from radon by guess from the effects of higher doses of alpha radiation.Such data comes primarily from studies of survivors of the atomic bombs that destroyed Hiroshima and Nagasaki in Japan. The customary extrapolation （推测 ） assumes that cancer risk is proportional to the dose of radiation even at low doses.
Radiation"s effects in cell structure don"t necessarily reflect what happens in "a whole organism， with its full range of defense repair mechanisms， " says Duport.Processes such as DNA repair and cell death triggered by radiation damage could cancel the effect on by stander cells observed in the lab， he suggests.
Furthermore， while a bystander effect can contribute to cancer， other cell-to-cell interactions in living tissue "may relieve increased risk." says Barry Michael， a radiation biophysicist at the Gray Cancer Institute in Northwood， England.One of these interactions halts cell division and hence cancer. "The jury is still out on whether cell-to-cell effects lead to a greater or lower risk， " Michael says.
The passage‘s main topic is__________. 查看材料
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