高中 中等 2021-01-18 共3题 173次下载


A novel way of making computer memories, using bacteria FOR half a century, the  5 of progress in the computer industry has been to do more with less. Moore’s law famously observes that the number of transistors which can be crammed into a given space 6 every 18 months. The amount of data that can be stored has grown at a similar rate. Yet as 7 get smaller, making them gets harder and more expensive. On May 10th Paul Otellini, the boss of Intel, a big American chipmaker, put the price of a new chip factory at around $10 billion. Happily for those that lack Intel’s resources, there may be a cheaper option—namely to mimic Mother Nature, who has been building tiny 8, in the form of living cells and their components, for billions of years, and has thus got rather good at it. A paper published in Small, a nanotechnology journal, sets out the latest example of the  9. In it, a group of researchers led by Sarah Staniland at the University of Leeds, in Britain, describe using naturally occurring proteins to make arrays of tiny magnets, similar to those employed to store information in disk drives. The researchers took their 10 from Magnetospirillum magneticum, a bacterium that is sensitive to the Earth’s magnetic field thanks to the presence within its cells of flecks of magnetite, a form of iron oxide. Previous work has isolated the protein that makes these miniature compasses. Using genetic engineering, the team managed to persuade a different bacterium—Escherichia coli, a ubiquitous critter that is a workhorse of biotechnology—to 11 this protein in bulk. Next, they imprinted a block of gold with a microscopic chessboard pattern of chemicals. Half the squares contained anchoring points for the protein. The other half were left untreated as controls. They then dipped the gold into a solution containing the protein, allowing it to bind to the treated squares, and dunked the whole lot into a heated 12 of iron salts. After that, they examined the results with an electron microscope. Sure enough, groups of magnetite grains had materialised on the treated squares, shepherded into place by the bacterial protein. In principle, each of these magnetic domains could store the one or the zero of a bit of information, according to how it was polarised. Getting from there to a real computer memory would be a long road. For a start, the grains of magnetite are not strong enough magnets to make a useful memory, and the size of each domain is huge by modern computing 13. But Dr Staniland reckons that, with enough tweaking, both of these objections could be dealt with. The 14 of this approach is that it might not be so capital-intensive as building a fab. Growing things does not need as much kit as making them. If the tweaking could be done, therefore, the result might give the word biotechnology a whole new meaning.

科普知识与现代技术 偏难 组卷次数:197


It isn’t just the beer that 15 to beer bellies. It could also be the extra calories, fat and unhealthy eating choices that may come with  16 drinking.

A recent study found that men consume an 17 433 calories (equivalent to a McDonald’s double cheeseburger) on days they drink a moderate amount of alcohol. About 61% of the caloric increase comes from the alcohol itself. Men also report eating higher amounts of saturated fats and meat, and less fruit and milk, on those days than on days when they aren’t drinking, the study showed. Women fared a bit better, taking in an extra 300 calories on moderate-drinking days, from the alcohol and eating fattier foods. But women’s increase in calories from additional eating wasn’t statistically significant, the study said. ‘Men and women ate less healthily on days they drank alcohol,’ said Rosalind Breslow, an epidemiologist with the federal National Institute on Alcohol Abuse and Alcoholism and lead author of the study. ‘Poorer food choices on drinking days have public-health 18, she said. The findings dovetail with controlled lab studies in which 19 generally eat more food after consuming alcohol. Researchers suggest that alcohol may enhance ‘the short-term rewarding effects’ of consuming food, according to a 2010 report in the journal Physiology & Behavior that reviewed previous studies on alcohol, appetite and obesity. But other studies have pointed to a different trend. Moderate drinkers gain less weight over time than either heavy drinkers or people who abstain from alcohol, particularly women, this research has shown. Moderate drinking is 20 having about two drinks a day for men and one for women. ‘People who gain the least weight are moderate drinkers, regardless of  beverage choice,’ said Eric Rimm, an associate professor of epidemiology and nutrition at Harvard Medical School and chairman of the 2010 review of alcohol in the federal dietary 21. The weight-gain difference is modest, and ‘starting to drink is not a weight-loss diet,’ he said. The various research efforts form part of a long-standing 22 about how alcohol affects people’s appetites, weight and overall health. Researchers say there aren’t simple answers, and suggest that individuals’ metabolism, drinking patterns and gender may play a role. Alcohol is ‘a real wild card when it comes to weight management,’ said Karen Miller-Kovach, chief scientific officer of Weight Watchers International. At seven calories per gram, alcohol is closer to fat than to carbohydrate or protein in caloric content, she said. Alcohol tends to lower restraint, she notes, causing a person to become more 23 with what they’re eating. Research bolstering the role of moderate drinking in helping to control weight gain was published in 2004 in the journal Obesity Research. That study followed nearly 50,000 women over eight years. An earlier study, published in the American Journal of Epidemiology in 1994, followed more than 7,000 people for 10 years and found that moderate drinkers gained less weight than nondrinkers. Studies comparing changes in waist circumference among different groups have yielded similar results. Dr. Rimm said it isn’t clear why moderate drinking may be 24 against typical weight gain, but it could have to do with metabolic adjustments. After people drink alcohol, their heart rate increases so they burn more calories in the following hour.

‘It’s a modest amount,’ he said. ‘But if you take an individual that eats 100 calories instead of a glass of wine, the person drinking the glass of wine will have a slight increase in the amount of calories burned.’

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October 31, 2009, California

Tsien Hsue-shen, PhD’39, one of the founders of the Jet Propulsion Laboratory, died on October 31, He was 98.

Tsien, bom in the eastern Chinese city of Hangzhou, graduated from the National Qinghua University in 1934 and in August of 1935 he left China to study at the Massachusetts Institute Technology. In 1936 he went to the California Institute of Technology to commence graduate studies. Tsien obtained his doctor degree in 1939 and would remain at Caltech for 20 years, becoming the Goddard Professor and establishing a reputation as one of the leading rocket scientists in the United States.

In 1943, Tsien and two others in the Caltech rocketry group drafted the first document to use the name Jet Propulsion Laboratory. During the Second World War, he was amongst the other scientists participated the "Manhattan Project". After World War II he served as a consultant to the United States Army Air Force. During this time, Conlonel Tsien worked on designing an intercontinental space plane. His work would inspire the X—20Dyna-Soar which would later be the inspiration for the Space Shuttle. In 1945 Tsien Hsue-shen married Jiang Ying, the daughter of Jiang Baili——one of the Chinese nationalist leader Chiang Kai—shen’s leading military strategists. But in 1950, the Chinese-born scientist was accused of harboring Communist sympathies and stripped of his security clearance.

In September 1955 he was permitted to leave for China, where Tsien resumed his research, founded the Institute of Mechanics, and went on to become the father of China’s missile program, a trusted member of the government and Party’s inner circle, and the nation’s most honored scientist, Tsien retired in 1991 and has maintained a low public profile in Beijing, China. The PRC government launched its manned space program in 1992 and used Tsien’s research as the basis for the Long March rocket which successfully launched the Shenzhou V mission in October of 2003. The elderly Tsien was able to watch China’s first manned space mission on television from his hospital bed.

In his late years, since the 1980s, Tsien devoted himself to spirituality research, and advocated scientific investigation of traditional Chinese medicine, Qigong and ""special human body functions".

1The underlined word "commence" in this passage probably means ________.

Amake up                                                   Bget

Cbegin                                                        Dpromise

2Tsien Hsue-shen got married at the age of ________.

A45                                                            B28

C24                                                            D34

3What is the right order of the events related to Tsien Hsue-shen?

a. his later life   

b. return to China

c. career in the U. S. A   

d. his early life and education

Aa-b-c-d                                                     Bd-c-b-a

Cd-b-c-a                                                     Dc-b-d-a

4Which of the following statements is NOT true?

ATsien Hsue-shen got a doctor’s degree in 1939.

BTsien Hsue-shen married Jiang Ying, the daughter of Chinese nationalist leader Chiang Kai-shen.

CTsien Hsue-shen has made a contribution to the Space Shuttle.

DTsien Hsue-shen was interested in traditional Chinese medicine, qigong and "special human body funcitions" in his later life.

科普知识与现代技术 很难 组卷次数:218