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What does plan to do in the future
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When Lewis Ziska wanted to see how a warmer wood with more carbon dioxide in the air would affect certain plants, he didn’t set up his experiment in a greenhouse or boot up a computer model. He headed for Baltimore. Cities are typically 7 degrees warmer than the countryside, as well as big sources of CO2. So Ziska, a plant physiologist at the U.S. Department of Agriculture, compa,ed ragweed growing in vacant lots in Baltimore with ragweed in rural fields—and discovered the dark side of sunny claims that global warming will produce a "greening of planet Earth". Urban ragweed grows three to five times bigger than rural ragweed, starts spewing allergenic pollen weeks earlier each spring and produces 10 times more pollen. In as few as 20 years the whole world will have CO2 levels at least as high as some cities do now. As climate changes due to the greenhouse effect, hayfever sufferers would do well to lay in copious supplies of Kleenex. From mosquitoes that carry tropical diseases such as malaria, to plants that produce allergenic pollen, scientists are finding that a warmer, CO2-rich world will be very, very. good for plants, insects and microbes that make us sick. Although the most obvious threat to human health is more frequent and more intense heat weaves, such as the one that killed thousands of people in Europe in 2003, that is only the beginning. In the case of plants, it’s not just that they grow faster and shed pollen earlier as the woad warms. The carbon-enriched air also alters their physiology. In a six-year study at a pine forest managed by Duke University, where pipes and fans adjust the CO2 concentration and the air, scientists found that elevated CO2 increases the growth rate of poison ivy. More surprising, by increasing the air’s ration of carbon to nitrogen, elevated CO2 also increases the toxicity of urushiol, the rash-causing oil. "Poison ivy will become not just more abundant in the future," says Ziska. "It will also be more toxic. " Plants interpret warmth and abundant CO2as: what a great climate for reproduction. Monitoring stations in Europe are recording higher pollen counts for allergenic grasses and trees, led by birch and hazel, notes a 2005 study by the Center for Health and the Global Environment at Harvard Medical School. Those counts are rising earlier each year: the warming already underway is shifting the pollen season by almost one day per year. By 2017, you’ll be reaching for tissues nine days sooner than you do now. More good news: in a greenhouse world po]len will be not only more abundant but more allergenic, he and Ziska find. Since cities already have the high CO2 levels that the rest of the world can soon expect, "’there is no question these climate-related changes have already begun," says Arlington, Texas, Mayo," Dr. Robert Cluck. "Every summner we’re seeing West Nile virus earlier and earlier, and the higher levels of ozone that come with higher temperatures are increasing the rates of asthma and causing heart and lung damage comparable to living with a cigarette smoker. " In a greenhouse world, tropical diseases will expand their range and their prevalence. For instance, alternating floods and droughts—the pattern that comes with climate change—provide perfect conditions for mosquitoes that carry malaria, West Nile and dengue fever. Warming makes mosquitoes bit more. They’ll face fewer predators, too. The frequent droughts expected in a greenhouse world are murder on damselflies and dragonflies. As dengue fever, yellow fever and malaria extend their range to higher elevations and higher latitudes, those diseases could appear in the developed woad, too. The southern tier of western and eastern Europe, as well as the southern United States, are most at risk, says Harvard’s Epstein. Dengue fever has already popped up on the Mexican side of the U.S. border, a worrisome expansion of its current range. Say this for the climate contrarians who insist that a warmer world will he a better, more productive world: if they’re referring to allergens and pathogens, they’re dead right. In Paragraph 2, when the author says "...that is only the beginning. " he means
接标准的性质分为三类的是技术标准、管理标准和工作标准。
在类型说明符号中，双精度浮点数用______表示，字符串型数据用______表示，整型数据用______表示。
What accounts for the great outburst of major inventions in early America-breakthroughs such as the telegraph, the steamboat and the weaving machine Among the many shaping factors, I would single out the country’’s excellent elementary schools; a labor force that welcomed the new technology; the practice of giving premiums to inventors; and above all the American genius for nonverbal," spatial" thinking about things technological. Why mention the elementary schools Because thanks to these schools our early mechanics ,especially in the New England and Middle Atlantic states, were generally literate and at home in arithmetic and in some aspects of geometry and trigonometry. Acute foreign observers related American adaptiveness and inventiveness to this educational advantage. As a member of a British commission visiting here in 1853 reported," With a mind prepared by thorough school discipline, the American boy develops rapidly into the skilled workman." A further stimulus to invention came from the "premium" system, which preceded our patent system and for years ran parallel with it. This approach, originated abroad, offered inventors medals, cash prizes and other incentives. In the United States, multitudes of premiums for new devices were awarded at country fairs and at the industrial fairs in major cities. Americans flocked to these fairs to admire the new machines and thus to renew their faith in the beneficence of technological advance. Given this optimistic approach to technological innovation, the American worker took readily to that special kind of nonverbal thinking required in mechanical technology. As Eugene Ferguson has pointed out," A technologist thinks about objects that cannot be reduced to unambiguous verbal descriptions; they are dealt with in his mind by a visual, nonverbal process. The designer and the inventor are able to assemble and manipulate in their minds devices that as yet do not exist." This nonverbal "spatial" thinking can be just as creative as painting and writing. Robert Fulton once wrote," The mechanic should sit down among levers, screws, wedges, wheels, etc., like a poet among the letters of the alphabet, considering them as an exhibition of his thoughts, in which a new arrangement transmits a new idea." When all these shaping forces-- schools, open attitudes, the premium system, a genius for spatial thinking -- interacted with one another on the rich U. S. mainland, they produced that American characteristic, emulation. Today that word implies mere imitation. But in earlier times it meant a friendly but competitive striving for fame and excellence. It is implied that adaptiveness and inventiveness of the early American mechanics______.
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