单选题Are smart people just naturally attracted to study art or perform music, dance, or drama? Or does early education in the art actually cause changes in the brain that develop important components of cognition? Recent findings show that there may be some significant causal relationships between arts training and the brain"s ability to learn. The Dana Foundation, an organization with interest in neuroscience, immunology, and arts education, just released a three-year study that found that early training in the arts is possibly good for your brain. Neuroscientists and psychologists at several universities have now enhanced understanding of just how the arts might improve thinking, memory, and language skills. Music education is linked with the ability to control both short-term and long-term memory, geometric representation, and development of reading skills. Dance training improves thinking though mimicry and acting classes seem to expand language. Visual arts lessons outside the classroom in childhood are linked to improved math calculations. In retrospect, I wish I had more art lessons before I took on that advanced math class in high school. It"s not a new idea that the arts can make us smarter. The notion caught fire in the 1990s when researchers showed that college students did better on certain math tests" after listening to a little bit of Mozart. And while the current report from the Dana Foundation did not provide definite theories as to how arts make us smart, what it does is to end the popular notion that people are either right-or left-brain learners. Apparently artists are not that fundamentally different and perhaps there is even an underlying connection between the cognitive processes that give rise to both arts to both arts and sciences.

单选题Do you remember all those years when scientists argued that smoking would kill us but the doubters insisted that we didn't know for sure? That the evidence was inconclusive, the science uncertain? That the antismoking lobby was out to destroy our way of life and the government should stay out of the way? Lots of Americans bought that nonsense, and over three decades, some 10 million smokers went to early graves. There are upsetting parallels today, as scientists in one wave after another try to awaken us to the growing threat of global warming. The latest was a panel from the National Academy of Sciences, enlisted by the White House, to tell us that the Earth's atmosphere is definitely warming and that the problem is largely man-made. The clear message is that we should get moving to protect ourselves. The president of the National Academy, Bruce Alberts, added this key point in the preface to the panel's report "Science never has all the answers. But science does provide us with the best available guide to the future, and it is critical that our nation and the world base important policies on the best judgments that science can provide concerning the future consequences of present actions. " Just as on smoking, voices now come from many quarters insisting that the science about global warming is incomplete, that it's OK to keep pouring fumes into the air until we know for sure. This is a dangerous game: by the 100 percent of the evidence is in, it may be too late. With the risks obvious and growing, a prudent people would take out an insurance policy now. Fortunately, the White House is starting to pay attention. But it's obvious that a majority of the president's advisers still don't take global warming seriously. Instead of a plan of action, they continue to press for more research — a classic case of "paralysis by analysis". To serve as responsible stewards of the planet, we must press forward on deeper atmospheric and oceanic research but research alone is inadequate. If the Administration won't take the legislative initiative, Congress should help to begin fashioning conservation measures. A bill by Democratic Senator Robert Byrd of West Virginia, which would offer financial incentives for private industry, is a promising start. Many see that the country is getting ready to build lots of new power plants to meet our energy needs. If we are ever going to protect the atmosphere, it is crucial that those new plants be environmentally sound.

单选题Why do people always want to get up and dance when they hear music? The usual explanation is that there is something embedded in every culture—that dancing is a "cultural universal". A researcher in Manchester thinks the impulse may be more deeply rooted than that. He says it may be a reflex reaction. Neil Todd, a psychologist at the University of Manchester, told the BA that he first got an inkling that biology was the key after watching people dance to deafeningly loud music. "There is a compulsion about it. " he says. He reckoned there might be a more direct, biological, explanation for the desire to dance, so he started to look at the inner ear. The human ear has two main functions, hearing and maintaining balance. The standard view is that these tasks are segregated so that organs for balance, for instance, do not have an acoustic function. But Todd says animal studies have shown that the sacculus, which is part of the balance-regulating vestibular system, has retained some sensitivity to sound. The sacculus is especially sensitive to extremely loud noise, above 70 decibel. " There" s no question that in a contemporary dance environment, the sacculus will be stimulated. " says Todd. The average rave, he says, blares music at a painful 110 to 140 decibels. But no one really knows what an acoustically stimulated sacculus does. Todd speculates that listening to extremely loud music is a form of "vestibular self-stimulation" : it gives a heightened sensation of motion. "We don"t know exactly why it causes pleasure. " he says. "But we know that people go to extraordinary lengths to get it. " He list bungee jumping, playing on swings or even rocking to and fro in a rocking chair as other example of pursuits designed to stimulate the sacculus. The same pulsing that makes us feel as though we are moving may make us get up and dance as well, says Todd. Loud music sends signals to the inner ear which may prompt reflex movement. "The typical pulse rate of dance music is around the rate of locomotion. " he says, "It"s quite possible you" re triggering a spinal reflex. "

单选题Having a few too many drinks can mean more than just a blackout or a bad hangover. People who engage in binge drinking are courting danger, experts warn. Binge drinking is most common at colleges and universities, where many adults treat drinking to excess as a rite of passage. A 1997 study from the Harvard School of Public Health reports that 42. 7% of all college students engage in binge drinking. The well-publicized deaths of several college students from binge drinking in 1997 highlights the risks. An 18-year-old freshman at the Massachusetts Institute of Technology drank himself into a coma and died. A 20-year-old fraternity pledge at Louisiana State University died from alcohol poisoning. "Alcohol is always toxic. It's really a poison, " said Steven Schandler, professor of psychology at Chapman University and chief of addiction research at the Long Beach Veterans Affairs Health Care System, who added that binge drinking can lead to alcohol poisoning. "Because it's a poison, like any other poison, if you take in a little bit, you might tolerate it, but if you take in a lot, you might die. " Administrators and doctors say that college freshmen are especially at risk for alcohol poisoning, in part because they often lack the maturity to refrain or stop. And for some who may be new to drinking, their bodies have a relatively low tolerance for alcohol. But problems with alcohol aren't limited to teenagers and young adults. A 39-year-old Buena Park man recently recalled that two days of steady imbibing on a trip to Las Vegas several years ago left him in bad shape. Doctors say blood alcohol levels of about 4%— five times the legal intoxication limit of 0. 8%—can induce potentially lethal side effects in most people. Alcoholics have higher limits. Although not well understood, enzymes that break down and expel alcohol in the liver and kidneys do so more effectively in seasoned drinkers, allowing them to tolerate more, Schandler said. Regardless of a person's tolerance, alcohol exerts its influence when the amount of alcohol taken in exceeds the amount that the body can digest. At that point, alcohol passes from the bloodstream into the brain and begins its attack. Alcohol first affects the brain's cortex, which controls more sophisticated thought processes. That's why people generally become less inhibited under the influence of alcohol, and some are more willing to try things that could be dangerous to themselves or others. Coordination, mainly controlled by the cerebellum, is the next to go, leading to slurred speech and difficulty walking in a straight line. As excessive drinking continues, alcohol moves deeper into the brain until "it gets to the very basic structure of the brain stem that affects things like respiration and heart beat, " said Dr. Bret Ginther, an assistant clinical professor of emergency medicine at UC Irvine. At that point, people may pass out or fall into a coma. Their vital signs may weaken. "The most common cause of death from alcohol poisoning is respiratory arrest, " said Ginther. Eventually, the heart simply stops. Getting to that point is fairly unusual. But Ginther said that at least once or twice a month, patients are brought into the emergency room at UCI Medical Center in Orange suffering from alcohol poisoning. College officials say they are always on the lookout for alcohol abuse but say there is no fail-safe method to keep students from drinking. Many colleges try to educate students, especially those caught drinking illegally or causing disruptions. The Higher Education Center for Alcohol and Other Drug Prevention in Newton, Mass, advocates a community-based approach that includes administrators, faculty, police and businesses in the fight to curb binge drinking, in part by being on alert for people abusing alcohol. The center also stresses the importance of parental guidance and urges parents to have frank discussions with their children about excessive drinking.

单选题Fear is often a【C1】______ emotion. When you become frightened, many physical changes occur within your body. Your heartbeat and【C2】______ quicken; your pupils expand to admit more light; large quantities of energy-producing adrenaline (肾上激素) are poured into your bloodstream.【C3】______ a fire or an accident, fear can【C4】______ life-saving flight. Similarly, when a danger is psychological rather than physical, fear can force you to take self-protective measures. It is only when fear is disproportional to the danger【C5】______ that it becomes a problem. Some people are simply more vulnerable【C6】______ fear than others. A visit to the newborn nursery of any large hospital will demonstrate that, from the moment of their births, a few fortunates respond calmly to sudden fear-producing situations such as a loudly slammed door. Yet a neighbor in the next bed may cry out with profound fright. From birth, he or she is more【C7】______ learn fearful responses because he or she has inherited a tendency to be more【C8】______ . Further, psychologists know that our early experiences and relationships strongly【C9】______ and determine our later fears. A young man named Bill, for example, grew up with a father who regarded each adversity as a【C10】______ obstacle to be overcome with imagination and courage. Using his father as a model, Bill came to welcome adventure and to trust his own ability to solve problems.

单选题The National Trust has worked for the preservation of places of historic interest and natural beauty in England, Wales and Northern Ireland. It is the largest landowner and conservation society in Britain. Wherever you go, you are close to land that is protected and【C1】______by the National Trust. Over 350 miles of【C2】______coastline; 90, 000 acres of land, lakes and forests in one area of natural beauty【C3】______; prehistoric and Roman ruins; moorlands and farmland, woods and islands; lengths of inland waterways; even seventeen whole villages—all are open to the public at all times subject only【C4】______the needs of farming, forestry and the protection of wildlife. But the Trust" s protection【C5】______further than this. It has in its possession a hundred gardens and【C6】______two hundred historic buildings which it opens to paying visitors. Castes and churches, houses of architectural or historic importance, mills, gardens and parks【C7】______to the Trust by their former owners. Many houses retain their【C8】______contents of fine furniture, pictures, and other treasures accumulated over generations, and often the donor himself continues to live in part of the house as a【C9】______the National Trust. The walking-sticks in the hall, flowers, silver-framed photographs, books and papers in the rooms are signs that the house is still loved and【C10】______and that visitors are welcomed as private individuals just as much as tourists.

单选题Planes may account for only 2 per cent of the world's carbon emissions, but it is a figure destined to rise. The aviation industry is expanding at a dramatic rate, around 5 percent a year. Twice as many passengers are likely to be passing through British airports in 2020 compared with today, and three times by 2030. As the developed world acknowledges climate change warnings, the carbon emissions from other industries will fall. The aviation industry's output will therefore account for an even larger percentage of emissions. One calculation, by the Climate Change Research (CCR), suggests the U. K. aviation industry could end up accounting for every gram of our carbon quota by 2040. Such calculations suppose aircraft designers cannot clean up their act, a suggestion firmly rejected by experts who point to a massive research program aimed at cutting fuel use by planes by around 50 percent by 2020, a move that would also halve their carbon emissions. To reach that aim, a key factor will be lightweight composites, materials made of several components, including carbon fibres. These are as strong and flexible as metal but as light as plasti C. Planes such as the Airbus A340 are already made of material that is 10 percent carbon composite. This cuts weight, decreases fuel use and reduces carbon emission. The next generation of aircrafts, will make even more use of composites: a tremendous saving in weight, fuel and carbon. Then there is the simple matter of air traffic control. At present, individual countries have their own routes for aircraft crossing their airspaces. "Essentially aircraft travel on dog-legs across Europe, and that is very inefficient in terms of fuel use, " said Dr. John Green, of the Royal Aeronautical Society. "We need to rationalize air traffic control so that planes fly in straight, energy-efficient lines, an idea that is now being discussed in the EU. " Finally, there is aviation fuel. Making it ecologically friendly poses the greatest challenges of all. Biofuels can be used as petrol and diesel substitutes for cars and lorries, but not in planes. "Biofuel is essentially alcohol, and that burns at the wrong temperature for aircraft engines, " says Green. "We can use coal to make kerosene, which we could burn in aircraft engines, but that does not help the issue of global warming, of course. " But this does not stop scientists from dreaming. One idea, put forward by the U. S. geneticist Craig Venter last week, would be to create micro-organisms, fitted with artificial chromosomes, which could convert sunlight into fuels that could be burnt in aircraft. These would not involve burning fossil carbon and would be the perfect green fuel. It is still a far-off prospect but realistic, say biologists.

单选题Today, I sit in a surgical ICU beside my favorite Jack as he recovers from a five-hour operation to repair a massive aortic aneurysm. For me it has been a journey into the medical system as an inexperienced consumer rather than in my usual position as a seasoned provider. This journey to an urban referral center has produced some disappointing surprises for Dad, and especially for me. For the past two days, my beloved Jack has been called "Harold"(his first name; Jack is his middle name). Of course, there is nothing wrong with "Harold"—it was what he was called in the army— but Dad never has been "Harold" except to those who really don"t know him. Telephone callers at our family home who asked for "Harold" were always red flags that the caller was a telemarketer or insurance salesperson. Dad doesn" t correct his physicians or the office receptionists—he is from the old school, where it is impolite to question or correct your physician. Once he was an almost ideal "Jack," strong, athletic, quietly confident and imminently trustworthy, but his recent renal failure and dialysis treatments , his stroke and his constant tremor have robbed him of his strength, mobility, and golf game, but not of his will or love of his family, part of the reason he agreed to undertake this risky operation at his advanced age was because his wife and sisters still need his protective support. With so much at risk, he faced this life-threatening challenge in a city far away from his home and friends and in a place where he is greeted as "Harold. "

单选题The scientists of the Renaissance brought about the most fundamental alterations in the world of thought, and they accomplished this feat by devising a new method for discovering knowledge. Unlike the medieval thinkers, who proceeded for the most part by reading traditional texts, the early modern scientists laid greatest stress upon observation and the formation of temporary hypothesis. The method of observation implied two things: namely, those traditional explanations of the behavior of nature should be empirically demonstrated, the new assumption being that such explanations could very well be wrong, and that new information might be available to scientists so they could penetrate beyond the superficial appearances of things. People now began to look at the heavenly bodies with a new attitude, hoping not solely to find the confirmation of Biblical statements about the firmament but, further, to discover the principles and laws that describe the movements of bodies. Observation was directed not only upon the stars but also in the opposite direction, toward the minutest constituents of physical substance. To enhance the exactness of their observations, they invented various scientific instruments. Lippershey, a Dutchman, invented the telescope in 1608, although Galileo was the first to make dramatic use of it. In 1590 the first compound microscope was created. The principle of the barometer(晴雨表) was discovered by Galileo's pupil Torricelli. The air pump, which was so important in creating a vacuum for the experiment that, proved that all bodies regardless of their weight or size fall at the same rate when there is no air resistance, was invented by Otto von Guericke( 1602 -1686). With the use of instruments and imaginative hypotheses, fresh knowledge began to unfold. Galileo discovered the moons around Jupiter, and Anton Leeuwenhoek( 1632-1723) discovered spermatozoa, protozoa, and bacteria. Whereas Nicolas Copernicus (1473 -1543) formed a new hypothesis of the revolution of, the earth around the sun, Harvey (1578 -1657) discovered the circulation of the blood. William Gilbert (1540 -1603) wrote a major work on the magnet, and Robert Boyle (1627 -1691), the father of chemistry, formulated his famous law concerning the relation of temperature, volume, and pressure of gases. Added to these inventions and discoveries was the decisive advance made in mathematics, especially by Sir Isaac Newton and Leibniz, who independently invented differential (微分学) and integral (积分学) calculus. The method of observation and mathematical calculation now became the hallmarks of modern science. The new scientific mode of thought in time influenced philosophic thought in two important ways. First, the assumption that the basic processes of nature are observable and capable of mathematical calculation and description had the effect of engendering another assumption, namely, that everything consists of bodies in motion, that everything conforms to a mechanical model. The heavens above and the smallest particles below all exhibit the same laws of motion. Even human thought was soon explained in mechanical terms, not to mention the realm of human behavior, which the earlier moralists described as the product of free will.

单选题There are only three available strategies for controlling cancer: prevention, screening and treatment. Lung cancer causes more deaths than any other types of cancer. A major cause of the disease is not【C1】______known; there is no good evidence that screening is much help; and treatment fails in about 90 percent of all cases. At present, therefore, the main strategy must be【C2】______. This may not always be true, of course, as for some other types of cancer, researches over the past few decades have produced (or suggested) some importance in prevention, screening or treatment. 【C3】______, however, we consider not what researchers may one day offer but what today's knowledge could already deliver that is not being delivered, then the most practical and cost-efficient opportunities for avoiding premature death from cancer, especially lung cancer, probably involve neither screening nor improved【C4】______, but prevention. This conclusion does not depend on the unrealistic assumption that we can eliminate tobacco. It merely assumes that we can reduce cigarette sales appreciably by raising prices or by【C5】______on the type of education that already appears to have a positive effect on cigarette assumption by white-collar workers and that we can substantially reduce the amount of tar【C6】______per cigarette. The practicability of preventing cancer by such measures applies not only in those countries, such as, the United States of America, because cigarette smoking has been common for decades, 25 to 30 percent of all cancer deaths now involves lung cancer, but also in those where it has become【C7】______only recently. In China, lung cancer as yet accounts for only 5 to 10 percent of all cancer deaths. This is because it may take as much as half a century for the rise in smoking to increase in the incidence to lung cancer. Countries where cigarette smoking is only now becoming widespread can expect enormous increase in lung cancer during the 1990's or early in the next century, 【C8】______prompt effective action is taken against the habit—indeed, such increase is already plainly evident in parts of the world. There are reasons why the preventions of lung cancer is of such overwhelming importance. First, the disease is extremely common, causing more deaths than any other types of cancer now【C9】______: secondly, it is generally incurable; thirdly, effective, practicable measures to reduce its incidence are already reliably known; and finally, reducing tobacco consumption will also have a substantial【C10】______on many other diseases.

单选题Can electricity cause cancer? In a society that literally runs on electric power, the very idea seems preposterous. But for more than a decade, a growing band of scientists and journalists has pointed to studies that seem to link exposure to electromagnetic fields with increased risk of leukemia and other malignancies. The implications are unsettling, to say the least, since everyone comes into contact with such fields, which are generated by everything electrical, from power lines and antennas to personal computers and micro-wave ovens. Because evidence on the subject is inconclusive and often contradictory, it has been hard to decide whether concern about the health effects of electricity is legitimate—or the worst kind of paranoia. Now the alarmists have gained some qualified support from the U. S. Environmental Protection Agency. In the executive summary of a new scientific review, released in draft form late last week, the EPA has put forward what amounts to the most serious government warning to date. The agency tentatively concludes that scientific evidence "suggests a casual link" between extremely low-frequency electromagnetic fields — those having very longwave-lengths — and leukemia, lymphoma and brain cancer, While the report falls short of classifying ELF fields as probable carcinogens, it does identify the common 60-hertz magnetic field as "a possible, but not proven, cause of cancer in humans". The report is no reason to panic—or even to lost sleep. If there is a cancer risk, it is a small one. The evidence is still so controversial that the draft stirred a great deal of debate within the Bush Administration, and the EPA released it over strong objections from the Pentagon and the White House. But now no one can deny that the issue must be taken seriously and that much more research is needed. At the heart of the debate is a simple and well-understood physical phenomenon: When an electric current passes through a wire, it generates an electromagnetic field that exerts forces on surrounding objects. For many years, scientists dismissed any suggestion that such forces might be harmful, primarily because they are so extraordinarily weak. The ELF magnetic field generated by a video terminal measures only a few milligauss, or about one-hundredth the strength of the earth's own magnetic field. The electric fields surrounding a power line can be as high as 10 kilovolts per meter, but the corresponding field induced in human cells will be only about 1 millivolt per meter. This is far less than the electric fields that the cells themselves generate. How could such minuscule forces pose a health danger? The consensus used to be that they could not, and for decades scientists concentrated on more powerful kinds of radiation, like X-rays, that pack sufficient wallop to knock electrons out of the molecules that make up the human body. Such "ionizing" radiations have been clearly linked to increased cancer risks and there are regulations to control emissions. But epidemiological studies, which find statistical associations between sets of data, do not prove cause and effect. Though there is a body of laboratory work showing that exposure to ELF fields can have biological effects on animal tissues, a mechanism by which those effects could lead to cancerous growths has never been found. The Pentagon is far from persuaded. In a blistering 33-page critique of the EPA report, Air Force scientists charge its authors with having "biased the entire document" toward proving a link. "Our reviewers are convinced that there is no suggestion that electromagnetic fields present in the environment induce or promote cancer, " the Air Force concludes. "It is astonishing that the EPA would lend its imprimatur on this report. " Then Pentagon's concern is understandable. There is hardly a unit of the modern military that does not depend on the heavy use of some kind of electronic equipment, from huge ground-based radar towers to the defense systems built into every warship and plane.

单选题Conventional wisdom about conflict seems pretty much cut and dried. Too little conflict breeds apathy(冷漠)and stagnation(呆滞). Too much conflict leads to divisiveness(分裂)and hostility. Moderate levels of conflict, however, can spark creativity and motivate people in a healthy and competitive way. Recent research by Professor Charles R. Schwenk, however, suggests that the optimal level of conflict may be more complex to determine than these simple generalizations. He studied perceptions of conflict among a sample of executives. Some of the executives worked for profit-seeking organizations and others for not-for-profit organizations. Somewhat surprisingly, Schwenk found that opinions about conflict varied systematically as a function of the type of organization. Specifically, managers in not-for-profit organizations strongly believed that conflict was beneficial to their organizations and that it promoted higher quality decision making than might be achieved in the absence of conflict. Managers of for-profit organizations saw a different picture. They believed that conflict generally was damaging and usually led to poor-quality decision making in their organizations. Schwenk interpreted these results in terms of the criteria for effective decision making suggested by the executives. In the profit-seeking organizations, decision-making effectiveness was most often assessed in financial terms. The executives believed that consensus rather than conflict enhanced financial indicators. In the not-for-profit organizations, decision-making effectiveness was defined from the perspective of satisfying constituents. Given the complexities and ambiguities associated with satisfying many diverse constituents executives perceived that conflict led to more considered and acceptable decisions.

单选题People from around the world flock to the United States expecting to find a better life. But to scientists" surprise, a growing body of evidence indicates that increasing familiarity with U. S. culture and society renders immigrants and their children far more susceptible to many mental and physical ailments, even if they attain financial success. The latest study of this phenomenon, directed by epidemiologist William A. Vega of the University of Texas, San Antonio, finds much higher rates of major depression, substance abuse, and other mental disorders in U. S. -born Mexican-Americans compared with both recent and long-standing Mexican-American immigrants. This pattern held regardless of education or income levels. Vega" s results appear at the same time as the release of a national report on declining physical and mental health in children of immigrant families. A panel convened by the National Research Council and the Institute of Medicine, both in Washington, D. C. ,reviewed previous studies and concluded that assimilation into a U. S. lifestyle may undermine the overall health of immigrant children much more than being poor does. In contrast, studies of nonimmigrant U. S. residents usually link poverty to poor physical and mental health. " The material on immigrant health shocked me when we first reviewed it," says panel member Arthus M Kleinman, a psychiatrist and anthropologist at Harvard Medical School in Boston. " Vega " s study is consistent with the panel" s conclusion that immigrants" health deteriorates with assimilation to U.S. society, declining toward general U. S. norms. " says Kleinman. Other studies have indicated that citizens of many countries, including Mexico, are healthier overall than U. S. citizens. Vega"s team interviewed 3,012 adults of Mexican origin, ages 18-59, living Fresno County, Calif. Of that number, 1,810 people identified themselves as immigrants. Interviews were in English or Spanish. Interviewers expressed an interest in health issues only and tried to minimize any tendency of participants to lie—due to U. S. residency concerns—about having immigrated. Nearly one-half of U. S. -born Mexican-Americans had suffered from at least one of 12 psychiatric disorders at some time in their lives, compared with only one-quarter of the immigrants. Common mental conditions in U. S. -born individuals included major depression, phobias and other anxiety disorders, and substance abuse and dependence. Prevalence rates for mental disorders were lowest for those who had immigrated within the past 13 years. The higher rates found among immigrants of 13 or more years still fell considerably below those for the native-born group.

单选题Vitamins and food-derived compounds are the focus of a large part of chemopreventive research, but a number of drugs being used for treatment may also be suitable for prevention. One such drug is tamoxifen, the anti-estrogen medication that has demonstrated great potency in the treatment of breast cancer. First synthesized in 1966 for birth-control research, tamoxifen is thought to thwart cancer by blocking estrogen receptors that, when occupied, stimulate cell proliferation. An on-going, 10-year study by a national collaborative group of US physicians and scientists and the National Cancer Institute is testing tamoxifen" s ability to prevent breast cancer in thousands of healthy women who are at increased risk for the disease. In earlier studies of breast cancer patients, tamoxifen reduced the incidence of new tumors in the unaffected breast by about 40 percent. Those figures providing the rationale for investigating tamoxifen as preventive agent. But although it has clearly been a boon to breast cancer patients, tamoxifen has side effects, the most serious of which are increased risks of uterine cancer and blood-clot formation. Because of those risks, some women" s health advocates have questioned the use of the compound by healthy women for prevention. Yet the knowledge gained from a large-scale preventive trial of tamoxifen could help researcher understand how to synthesize a second generation of anti-estrogen drugs having greater potency and fewer risks than those associated with tamoxifen itself. We have every reason to believe that the power of chemoprevention is sure to grow as researchers continue to identify promising new chemoprevention agents and clinical trials begin to provide insights into these substances" effects in humans. With the advance of these investigations and our greater understanding of cancer, chemoprevention will undoubtedly play a major role in reducing cancer incidence as well as the number of deaths caused by the disease.

单选题For years, scientists have been warning us that the radiation from mobile phones is detrimental to our health, without actually having any evidence to back these【C1】______up. However research now suggests that mobile phone radiation has at least one positive side effect it can help prevent Alzheimer's,【C2】______in the mice that acted as test subjects. It's been suspected, though never proven, that heavy use of mobile phone is bad for your health. It's thought that walking around with a cellphone permanently attached to the side of your head is almost sure to be【C3】______your brain. And that may well be true, but I'd rather wait until it's proven before giving up that part of my daily life. But what has now been proven, in a very perfunctory manner, is that mobile phone radiation can have an effect on your brain. 【C4】______in this case it was a positive rather than negative effect. According to BBC News, the Florida Alzheimer Disease Research Center conducted a study on 96 mice to see if the radiation given off by mobile phone could affect the onset of Alzheimer's. Some of the mice were "genetically altered to develop beta-amyloid plagues in their brains"【C5】______they aged. These are a marker of Alzheimer's. All 96 mice were then "exposed to the lector-magnetic【C6】______generated by a standard phone for two one-hour periods each day for seven to nine months. "The lucky things. 【C7】______, the experiment showed that the mice altered to be predisposed to dementia were protected from the disease if exposed before the onset of the illness. Their cognitive abilities were so unimpaired as to be virtually【C8】______to the mice not genetically altered in any way. Unfortunately, although the results are positive, the scientists don't actually know why exposed to mobile phone radiation has this effect. But it's hoped that further study and testing could result in a non-invasive【C9】______for preventing and treating Alzheimer's disease. Autopsies carried out on the mice also concluded no ill-effects of their exposure to the radiation. However the fact that the radiation prevented Alzheimer's means mobile phones【C10】______our brains and bodies in ways is not yet explored. And it's sure there are negatives as well as this one positive.

单选题The U. S. may so far have enjoyed good luck in escaping a direct SARS hit, but officials aren" t leaving anything to chance. The best hope for averting a SARS epidemic at home will be to keep SARS out at the nation" s borders. Federal immigration laws authorize immigration authorities to exclude non-citizens who are determined to have a "communicable disease of public health significance". Immigration law also authorizes the President by proclamation to suspend the entry of any group of aliens whose entry he deems to be detrimental to the interests of the United States. This little-used power could be deployed to exclude all aliens from affected areas, a policy Taiwan has recently implemented. Under the Public Health Service Act, any individual(citizens included)may be quarantined at an international port of entry if they are reasonably believed to be carrying a designated communicable disease. As of an April 4 Executive Order by President Bush, SARS is now a designated disease. Thus, in tandem with airline screening, federal health authorities are carefully monitoring travelers from affected areas in Asia for SARS symptoms. With an estimated 25 ,000 individuals entering the country legally from Asia on a daily basis, that is a tall order. A single SARS-infected person getting through the net could bring down the border strategy. The U. S. government might also reinforce the border strategy through restrictions on travel by American citizens to affected areas. In a series of Cold War era decisions, the Supreme Court upheld international travel restrictions for national security reasons, and one can imagine the same rationale applying to a public health emergency. How practical it would be to prohibit—and police—a travel ban to countries such as China is another question. The initial SARS defense, then, hinges on effective border control. But U. S. borders are far from under control. There are an estimated 8~9 million undocumented aliens now in the United States, a figure growing by as many as 500,000 per year. Asia is the largest contributor to undocumented immigration outside the western hemisphere, funneling illegal aliens into the United States through elaborate smuggling networks. SARS could just as easily make serious inroads into the U. S. through this backdoor rather than the front.

单选题Children are getting so fat they may be the first generation to die before their parents, an expert claimed yesterday. Today's youngsters are already falling prey to potential killers such as diabetes because of their weight. Fatty fast-food diets combined with sedentary lifestyles dominated by televisions and computers could mean kids will die tragically young, says Professor Andrew Prentice, from the London School of Hygiene and Tropical Medicine. At the same time, the shape of the human body is going through a huge evolutionary shift because adults are getting so fat. Here in Britain, latest research shows that the average waist size for a man is 36~38in and may be 42~44in by 2032. This compares with only 32. 6in in 1972. Women's waists have grown from an average of 22 inches in 1920 to 24 inches in the Fifties and 30 inches now. One of the major reasons why children now are at greater risk is that we are getting fatter younger. In the UK alone, more than one million under-16s are classed as overweight or obese — double the number in the mid-Eighties. One in ten four-year-olds are also medically classified as obese. The obesity pandemic—an extensive epidemic—which started in the US, has now spread to Europe, Australia, Central America and the Middle East. Many nations now record more than 20 per cent of their population as clinically obese and well over half the population as overweight. Prof Prentice said the change in our shape has been caused by a glut of easily available high-energy foods combined with a dramatic drop in the energy we use as a result of technology developments. He is not alone in his concern. Only last week one medical journal revealed how obesity was fuelling a rise in cancer cases. Obesity also increases the risk factor for strokes and heart disease. An averagely obese person's lifespan is shortened by around nine years while a severely obese person by many more. Prof Prentice said: "So will parents outlive their children, as claimed recently by an American obesity specialist?" The answer is yes—and no. Yes, when the offspring become grossly obese. This is now becoming an alarmingly common occurrence in the US. Such children and adolescents have a greatly reduced quality of life in terms of both their physical and psychosocial health. So say No to that doughnut and burger.

单选题Osteoporosis used to be called "the silent disease" because its victims didn' t know they had it until it was too late and they suffered a bone fracture. Today, doctors can identify osteoporosis early. Improved understanding of the disease has also led to new treatments and strategies for preventing the disease altogether. For post-menopausal women, the most common medical response to osteoporosis is hormone replacement therapy. Boosting estrogen levels strengthens the entire skeleton and reduces the risk of hip fracture. Unfortunately, it sometimes causes uterine bleeding and may increase the risk of breast cancer. To bypass such side effects, researchers have developed several alternative treatments. Synthetic estrogens called Selective Estrogen Receptor Modulators (SERMs) emulate estrogen with slight modifications. Another drug, alendronate, reduces spine, hip and wrist fractures by 50 percent. Researchers have even developed a nasal spray called calcitonin. Each of these alternatives has trade-offs, however. Patients must talk with their doctors to decide which therapy is best for them. The ideal way to address osteoporosis is by adopting a healthy lifestyle. And the best time to do this is in childhood, when most bone mass is accumulated. Because bodies continue building bone until about age thirty, some experts believe that women in their twenties can still increase their bone strength by as much as 20 percent. Calcium, which is available in low-fat dairy foods and dark green vegetables, is essential for preventing osteoporosis. So is vitamin D, which aides calcium absorption. Vitamin D comes from sunlight, but dietary supplements may be helpful in northern climates and among those who don't get outside. The final component is regular moderate exercise because bone responds to the needs that the body puts on it. These are the simple steps that can help make "the silent disease" truly silent.

单选题The discovery of the Antarctic not only proved one of the most interesting of all geographical adventures, but created what might be called "the heroic age of Antarctic exploration". By their tremendous heroism, men such as Shackleton, Scott, and Amundsen caused a new continent to emerge from the shadows and yet that heroic age, little more than a century old, is already passing. Modern science and inventions are revolutionizing the techniques of former explorers, and, although still calling for courage and feats of endurance, future journey into these icy wastes will probably depend on motor vehicles equipped with caterpillar traction rather than on the dogs that earlier discoverers found so invaluable. Few realize that this Antarctic continent is almost equal in size to South America, and enormous field of work awaits geographers and prospectors. The coasts of this continent remain to be accurately charted, and the mapping of the whole of the interior presents formidable task to the cartographers who undertake the work. Once their labors are completed, it will be possible to prospect the vast natural resources which scientists believe will furnish one of the large treasure hoards of metals and minerals the world has yet known, and almost inexhaustible sources of copper, coal, uranium, and many other ores will become available to man. Such discoveries will usher in an era of practical exploitation of the Antarctic wastes. The polar darkness which hides this continent for the six winter months will be defeated by huge batteries of light, and make possible the establishing of airfields for the future intercontinental air service by making these areas as light as day. Present flying routes will completely change, for the Antarctic refueling bases will make flight from Australia to South America comparatively easy over the 5 000 miles journey. The climate is not likely to offer an insuperable problem, for the explorer Admiral Byrd has shown that the climate is possible even for men completely untrained for expeditions into those frozen wastes. Some of his party were men who had never seen snow before, and yet he records that they survived the rigors of the Antarctic climate comfortably, so that, provided that the appropriate installations are made, we may assume that human beings from all countries could live there safely. Byrd even affirms that it is probably the most health climate in the world, for the intense cold of thousands of years has sterilized this continent, and rendered it absolutely germfree, with the consequences that ordinary and extraordinary sicknesses and disease from which man suffers in other zones with different climates are here utterly unknown. There exist no problems of conservation and preservation of food supplies, for the latter keep indefinitely without any signs of deterioration; it may even be that later generations will come to regard the Antarctic as the natural storehouse for the whole world. Plans are already on foot to set up permanent bases on the shores of this continent, and what so few years ago was regarded as a " dead continent" now promises to be a most active centre of human life and endeavor.

单选题Charles Paul and his wife, Hazel, stopped using the motor home they bought several years ago; it sits idle behind their house in Richardson, Texas. Travel is just one sacrifice they made to pay for the cost of their prescriptions, more than a dozen medications for the two of them. They found relief by switching drugstores, to one in nearby McKinney. A prescription for Paul" s diabetes had cost $ 89. 88 when he got it from a national chain but dropped down to $ 58 from McKinney" s Smith Drug. Smith, which claims to be the oldest drugstore in Texas, has been getting a lot of attention since a Dallas newspaper touted its astoundingly low prices. The overwhelming response from the public has been " a little scary," says co-owner Kaylei Mosier. She says the store simply marks each prescription up enough to cover its costs, but for many prescriptions that" s a lot lower than at other stores. The Smith Drug story has highlighted a little-known fact: prescription prices vary from city to city and block to block, and a little research can save consumers hundreds or thousands of dollars. Insurance copays can make these differences invisible, but they" re a huge deal to the 45 million uninsured Americans. Why the price swings? Howard Schiff, executive director of the Maryland Pharmacists Association , explains that pharmacies generally buy their drugs from a wholesaler, who doesn" t sell to every drugstore at the same price. Once the drug is in the pharmacy, each owner chooses how much to mark it up. Because fewer than 10 percent of consumers comparison-shop for prescriptions the way they might for a quart of milk—and drug prices generally are not advertised—pharmacies don" t worry that higher prices will drive people away, says Stanford economist Alan Scorensen. There is a downside to hopping from drugstore to drugstore. If people price-shop, they" re going to lose some protection that comes from having one pharmacy track all your medications. Going to many pharmacies keeps one pharmacist from noticing potentially harmful interactions between prescriptions. Comparison-shopping is further complicated because pharmacies that have the best price on one drug don" t usually have the lowest prices across the board, so finding a good price on one drug at a pharmacy does not guarantee a cheaper total bill.