单选题I was invited to present a lecture to a class of graduate nurses who were studying the " Psychosocial Aspects of Aging. " I started my lecture with the following case presentation: The patient is a white female who appears her reported age. She neither speaks nor comprehends the spoken word. Sometimes she babbles incoherently for hours on end. She is disoriented about person, place, and time. She does, however, seem to recognize her own name. I have worked with her for the past 6 months, but she still does not recognize me. She shows complete disregard for her physical appearance and makes no effort whatsoever to assist in her own care, she must be fed, bathed, and clothed by others. Because she is edentulous, her food must be pureed, and because she is incontinent of both urine and stool, she must be changed and bathed often. Her shirt is generally soiled from almost incessant drooling. She does not walk. Her sleep pattern is erratic. Often she awakens in the middle of the night, and her screaming awakens others. Most of the time she is friendly and happy. However, several times a day she gets quite agitated without apparent cause. Then she screams loudly until someone comes to comfort her. After the case presentation, I asked the nurses how they would feel about taking care of a patient such as the one described. They used words such as " frustrated," " hopeless, " " depressed, " and "annoyed" to describe how they would feel. When I stated that I enjoyed taking care of her and that I thought they would too, the class looked at me in disbelief. I then passed around a picture of the patient; my 6-month-old daughter. After the laughter had subsided, I asked why it was so much more difficult to care for a 90-year-old than a 6-month-old with identical symptoms. We all agreed that it is physically easier to take care of a helpless baby weighing 15 pounds than a helpless adult weighing 100, but the answer seemed to go deeper than that. The infant, we all agreed, represents new life, hope, and almost infinite potential. The demented senior citizen, on the other hand, represents the end of life, with little potential for growth. We need to change our perspective. The aged patient is just as lovable as the child. Those who are ending their lives in the helplessness of old age deserve the same care and attention as those who are beginning their lives in the helplessness of infancy.

单选题Physics and chemistry have furnished the techniques for biologists to take the exploration of life to its logical conclusion. This event demands a wider audience. The pattern of discovery cannot be predicted, but the tool kit now in the possession of biologists is so powerful that no known problem seems likely to hold its mysteries for long. By usurping the tools with which living cells manipulate DNA, biologists can cut the genetic material at chosen points and amplify target segments for further study. Techniques and software for sequencing the order of chemical units in DNA are now so sophisticated that the full human gene set seems likely to be sequenced within the next ten years. It is only a matter of time before biologists catalogue the 75 ,000 or so human genes; identify the signals that switch each gene on and off; figure out what sets of active genes characterize each of the 200 or so major types of human cells, and determine how the consortium of interacting cells, and determine how the consortium of interacting cell types operates as an organism. Such knowledge has larger consequences than scientists can deal with alone. Genes do not determine everything, but they set the boundaries of an individual' s full potential. They probably decree major elements of personality and intelligence. They create a predisposition to various diseases. Knowledge of how the human machine is assembled implies the knowledge to repair, refine and improve it. The first attempts at gene therapy have mostly stumbled, but the technique will surely be made to work eventually. The idea of correcting defective genes is not particularly controversial. But a fundamental solution to the creeping burden of Medicare—equipping every embryo with a birthright package of genes for good health, longevity and aversion to nicotine and violence—would raise knottier issues. Critics will doubtlessly warn darkly of dangerous knowledge. But more knowledge is generally better than less. Molecular biology, long gathering speed, is about to take off. It is almost ready to become a spectator sport, not just a private club for academics and biotechnology companies.

单选题In the college-admissions wars, we parents are the true fighters. We are pushing our kids to get good grades, take SAT preparatory courses and build resumes so they can get into the college of our first choice. I"ve twice been to the wars, and as I survey the battlefield, something different is happening. We see our kids" college background as a prize demonstrating how well we"ve raised them. But we can"t acknowledge that our obsession(痴迷)is more about us than them. So we"ve contrived various justifications that turn out to be half-truths, prejudices or myths. It actually doesn"t matter much whether Aaron and Nicole go to Stanford. We have a full-blown prestige panic; we worry that there won"t be enough prizes to go around. Fearful parents urge their children to apply to more schools than ever. Underlying the hysteria(歇斯底里)is the belief that scarce elite degrees must be highly valuable. Their graduates must enjoy more success because they get a better education and develop better contacts. All that is plausible— and mostly wrong. We haven"t found any convincing evidence that selectivity or prestige matters. Selective schools don"t systematically employ better instructional approaches than less selective schools. On two measures — professors" feedback and the number of essay exams — selective schools do slightly worse. By some studies, selective schools do enhance their graduates" lifetime earnings. The gain is reckoned at 2-4% for every 100-point increase in a school"s average SAT scores. But even this advantage is probably a statistical fluke(偶然). A well-known study examined students who got into highly selective schools and then went elsewhere. They earned just as much as graduates from higher-status schools. Kids count more than their college. Getting into Yale may signify intelligence, talent and ambition. But it"s not the only indicator and, paradoxically, its significance is declining. The reason: so many similar people go elsewhere. Getting into college is not life only competition. Old-boy networks are breaking down. Princeton economist Alan Krueger studied admissions to one top Ph.D. program. High scores on the GRE helped explain who got in; degrees of prestigious universities didn"t. So, parents lighten up. The stakes have been vastly exaggerated up to a point, we can rationalize our pushiness. America is a competitive society; our kids need to adjust to that. But too much pushiness can be destructive. The very ambition we impose on our children may get some into Harvard but may also set them up for disappointment. One study found that, other things being equal, graduates of highly selective schools experienced more job dissatisfaction. They may have been so conditioned to being on top that anything less disappoints.

单选题WELL—do they or don"t they? For years, controversy has raged over whether the electromagnetic fields produced by power lines could cause cancer especially leukemia in young children. But in Britain last week confusion reached new heights. One team from Bristol announced that it had evidence to back a controversial but plausible theory which would explain how power lines might cause cancer(electric fields attract airborne pollutants). Only to be followed by the release of results by another group in London which suggested there is nothing to worry about. What is going on? Actually, the confusion may be more apparent than real. There can be no doubt that the effects of power lines on water droplets, pollutants and naturally occurring radon uncovered by the Bristol team are real and interning. But to suggest that they have anything to do with leukemia in children is premature. The extra exposure to pollution for a child living near power lines would be tiny, and it is not obvious why radon, a gas normally associated with lung cancer—would cause leukemia in children. The second study, which drew reassuring blank, is the world" s biggest ever probe of the statistical link between childhood cancers and magnetic fields of the sort produced by power lines and electrical appliances. It is one of several recent studies that have failed to find a link. Unlike earlier research, these newer studies involved going into homes to measure the electromagnetic fields. The fields they measured included input from major power lines if they were. Which is not to say the research is perfectly. Critics argue that Britain" s childhood cancer study, for example, has not yet taken into account the surges in exposure that might come from, say, switching appliances on and off. And some people might wonder why measurements of the electric fields that are also produced by power lines did not figure in last week" s study. But neither criticism amounts to a fatal blow. Electrical fields cannot penetrate the body significantly, for example. A more serious concern is whether the British research provides an all-clear signal for such countries as the US where power lines carry more current and therefore produce higher magnetic fields. Pedants(书呆子)would conclude that it doesn" t. But these counties will not have long to wait for answers from a major Japanese study. In Britain the latest epidemiological study can be taken as the final word on the matter. If the electromagnetic fields in British homes can in some unforeseen way increase the risk of cancer, we can now be as certain as science allows that the increase is too tiny to measure.

单选题The United States and England each has a major—and unique—health-care challenge, according to a study comparing the health of senior citizens in the two countries. The study, conducted by researchers from RAND Corporation in the United States and Institute for Fiscal Studies in the United Kingdom, found that disease and health disorder incidence was higher among U. S. senior citizens, but mortality rates were higher among English senior citizens. Americans aged 65 and older have almost twice the rate of diabetes found among their English counterparts and more than double the rate of cancer. Nevertheless, death rate among Americans 65 and older is lower. "Americans are a sicker group of people who tend to live longer, " says James Smith, a study co-author. He attributes the U. S. health problems to lifestyle factors, including poor eating habits and inadequate exercise. Americans tend to eat much larger servings of food, for example, "There is what I call an American plate. When we go to a restaurant, it's a plate I can't even eat any more. It's a plate with so much food on if it's not even appealing to me. " Smith also says that English adults are generally much more physically active than Americans. Biking and walking are much common in everyday life in England. He observes that "there is a lot of walking in London, and there is a lot of bicycle riding. I don't see people in downtown Los Angeles on their bicycles". On the other hand, England's problem is that doctors fail to diagnose serious conditions early enough. American doctors tend to screen patients for cancer, diabetes, and other illnesses more frequently. Smith notes "American medicine is much more aggressive. It leads to high costs, but it has benefits, too".

单选题You are busy filling out the application form for a position you really need; let" s assume you once actually completed a couple of years of college work or even that you completed your degree. Isn" t it tempting to lie just a little, to claim on the form that your diploma represents a Harvard degree? Or that you finished an extra couple of years back at State University? More and more people are resorting to outright deception like this to land their first job or to move ahead in their careers, for personnel officers, like most Americans, value degrees from prestigious schools. A job applicant may have a good education anyway, but he or she assumes that chances of being hired are better with a diploma from a well-known university. Registrars at most well-known colleges say they deal with fraudulent claims like these at the rate of about one per week. Personnel officers do check up on degrees listed on application forms, then. If it turns out that an applicant is lying, most colleges are reluctant to accuse the applicant directly. One Ivy League school calls them " impostors" ; another refers to them as " special cases". One well-known West Coast school, in perhaps the most delicate of all, says that these claims are made by " no such people" . To avoid outright lies, some job-seekers claim that they "attended" or "were associated with" a college or university. After carefully checking, a personnel officer may discover that "attending" means flunking out after one semester. It may tie that "being associated with" a college means that the job-seeker visited his younger brother for a football weekend. One school that keeps records of false claims says that the practice dates back at least to the turn of the century—that" s when they began keeping records, anyhow. If you don" t want to lie or even stretch the truth, there are companies that will sell you a phon-y diploma. One company, with offices in New York and on the West Coast, will put your name on a diploma from any number of nonexistent colleges. The price begins at around twenty dollars for a diploma from "Smoot State University". The prices increase rapidly for a degree from the "University of Purdue". As there is no Smoot State and the real school in Indiana is properly called Purdue University, the prices seem rather high for one sheet of paper.

单选题A mother who is suffering from cancer can pass on the disease to her unborn child in extremely rare cases,【C1】______a new case report published in PNAS this week. According to researchers in Japan and at the Institute for Cancer Research in Sutton, UK, a Japanese mother had been diagnosed with leukemia a few weeks after giving birth,【C2】______tumors were discovered in her daughter's cheek and lung when she was 11 months old. Genetic analysis showed that the baby's cancer cells had the same mutation as the cancer cells of the mother. But the cancer cells contained no DNA whatsoever from the father,【C3】______would be expected if she had inherited the cancer from conception. That suggests the cancer cells made it into the unborn child's body across the placental barrier. The Guardian claimed this to be the first【C4】______case of cells crossing the placental barrier. But this is not the case — microchimerism,【C5】______cells are exchanged between a mother and her unborn child, is thought to be quite common, with some cells thought to pass from fetus to mother in about 50 to 75 per cent of cases and to go the other way about half【C6】______. As the BBC pointed out, the greater【C7】______in cancer transmission from mother to fetus had been how cancer cells that have slipped through the placental barrier could survive in the fetus without being killed by its immune system. The answer, in this case at least, lies in a second mutation of the cancer cells, which led to the【C8】______of the specific features that would have allowed the fetal immune system to detect the cells as foreign. As a result, no attack against the invaders was launched. 【C9】______, according to the researchers there is little reason for concern of "cancer danger". Only 17 probable cases have been reported worldwide and the combined【C10】______of cancer cells both passing the placental barrier and having the right mutation to evade the baby's immune system is extremely low.

单选题Fourteen-year-old Sean MeCallum lay in a hospital bed waiting for a new heart. Without it, Scan would die. Sean" s case is not unusual. Everyday many people die because there just aren" t enough human organs to go around. Now scientists say they can alter the genetic make-up of certain animals so that their organs may be acceptable to humans. With this gene-altering technique to overcome our immune rejection to foreign organs, scientists hope to use pig hearts for transplants by the year 2008. That prospect, however, has stirred up strong opposition among animal fight activists. They protest that the whole idea of using animal organs is cruel and unjust; some scientists also fear such transplants may transform unknown diseases to humans. Others believe transplanting animal organs into humans is unnecessary. Millions of dollars spent on breeding pigs for their organs could be better spent on health education programs. They believe seventy-five percent of the heart disease cases that lead to a need for organ transplant are preventable. The key is to convince people to eat healthfully, and not to smoke or drink alcohol. Scientists could also use research funds to improve artificial organs. Still others believe that though new inventions and prevention programs may help, spending money to encourage more people to donate their organs is an even better idea. If enough people were educated about organ donations, everyone who needed an organ could be taken off the waiting list in a year.

单选题English speakers pick up pitch in the right hemispheres of their brains, but speakers of certain other languages perceive it on the left as well. It all depends on what you want to learn from pitch, Donald Wong of the Indiana School of Medicine in Indianapolis told the meeting last week. Earlier studies have shown that when an English speaker hears pitch changes, the right prefrontal cortex leaps into action. This fits in with the idea that emotive nuances of language—which in English are often carried by the rise and fail of the voice—are perceived on the right. But in "tonal" languages like Thai, Mandarin and Swedish, pitch not only carries emotional information, but can also alter the meaning of a word. Wong and his colleagues suspected that a speaker of tonal language would register pitch in the left side of the brain—in particular Broca" s area, which processes the linguistic content of language. To test this, the team asked English speakers and Thai speakers to listen to 80 pairs of Thai words, and tracked the blood flow in their brains using positron emission tomography. The volunteers had to decide whether the two words sounded the same, either by consonant or by tone. In some eases, the words had no intelligible meaning. None of the words was emotionally charged, so even when Thai speakers could understand them, there was no right-side activation. But sure enough the Thai speakers consistently lit up the left side of the brain, especially Broca" s area, while the English speakers did not. The researchers are now planning to repeat the experiment with Thai speakers using whole sentences , complete with emotional information. " Both hemispheres will be engaged, " predicts Wong.

单选题Some futurologists have assumed that the vast upsurge of women in the workforce may portend a rejection of marriage. Many women, according to this hypothesis, would rather work than marry. The converse of this concern is that the prospects of becoming a multi-paycheck household could encourage marriage. In the past, only the earnings and financial prospects of the man counted in the marriage decision. Now, however, the earning ability of a woman can make her more attractive as a marriage partner. Data show that economic downturns tend to postpone marriage because the parties cannot afford to establish a family or are concerned about rainy days ahead. As the economy rebounds, the number of marriages also rises. Coincident with the increase in women working outside the home is the increase in divorce rates. Yet, it may be wrong to jump to any simple cause-and-effect conclusions. The impact of a wife's work on divorce is no less cloudy than its impact on marriage decisions. The realization that she can be a good provider may increase the chances that a working wife will choose divorce over an unsatisfactory marriage. But the reverse is equally plausible. Tensions grounded in financial problems often play a key role in ending a marriage. Given high unemployment, inflationary problems, and slow growth in real earnings, a working wife can increase household income and relieve some of these pressing financial burdens. By raising a family's standard of living, a working wife may strengthen her family's financial and emotional stability. Psychological factors also should be considered. For example, a wife blocked from a career outside the home may feel caged in the house. She may view her only choice as seeking a divorce. On the other hand, if she can find fulfillment through work outside the home, work and marriage can go together to create a stronger and more stable union. Also, a major part of women's inequality in marriage has been due to the fact that, in most cases, men have remained the main breadwinners. With higher earning capacity and status occupations outside of the home comes the capacity to exercise power within the family. A working wife may rob a husband of being the master of the house. Depending upon how the couple reacts to these new conditions, it could create a stronger equal partnership or it could create new insecurities.

单选题Monkeys and chimpanzees, although they are weaker and less fierce than many other animals, possess brains which are far along the evolutionary road as any creature other than man. Birds can perform marvels of aerobatics, they can catch insects on the wing with unparalleled skill, navigate in a remarkable manner half round the world and back—but they can cannot think and reason. In technical terms it can be said that they are lacking in insight. The abilities which they do possess are built-in instincts derived from their genetic inheritance. Monkeys, on the other hand, can reason. They can easily remember a lighted door indicating the presence of food. They can remember what kind of food they are looking for. A monkey set the problem of reaching a banana, say, hung high up in its cage, can work out a system for getting it even if it involves piling up boxes to stand on and then knocking down the banana with a stick. A charming story is told about the psychologist Wolfgang Kobler, who had provided various boxes and other apparatuses by which he proposed to test a chimpanzee's ability to think out a method of reaching a fruit hung nine feet in the air. The animal looked about it and sized up the problem. Then it took Kobler by the hand, led him to a position immediately under the banana, jumped upon to his shoulder and reached it down from there. But evolution, although it has brought monkeys to a remarkable degree of cleverness, has stopped short at a crucial ability, the possession of which places man at a clearly superior level. Their minds cannot cope with abstract ideas. For example, an ape can be taught to fill a can with water from a barrel and take the can of water to put out a fire so that it can reach into a box and get food. But if the whole set-up is arranged on a raft the animal will continue to draw its water only from the barrel. It cannot grasp that any water, taken more, conveniently, say, from the pond on which the raft is floating, will putout the fire just as well. The abstract idea that water puts out fire is beyond it. The abstract idea that water puts out fire is beyond it.

单选题Memory can be both enhanced and impaired by the use of drugs. To date, most of the research in this area has focused on the short- and long-term effects of alcohol. Overall, the results show that alcohol interferes with the ability to encode new information but has relatively little effect on the retrieval of data already stored in long-term memory(Bimbaum et al., 1978). Heavy use of alcohol, however, may result in significant memory loss. In some cases, everything that was said or done while intoxicated is completely blocked out of memory. The person may fail to remember even highly significant events - such as having injured somebody! In extreme cases, chronic alcoholism may result in Korsakoff" s psychosis, a disorder characterized by gross memory defects and disorientation. Sufferers of Korsakoff" s psychosis may lose track of their own names, where they came from, or where they are. The effects of marijuana on memory are far less clear. In one study, subjects who had smoked marijuana experienced unusual difficulty in transferring information from short- to long-term memory. They could recall items for a brief period, but as time progressed, they forgot more and more of the information(Klatzky, 1980). Like alcohol, marijuana appears to interfere with the ability to encode and store data in long-term memory. There are drugs that actually enhance memory. Perhaps the most promising of these is DDAVP, a synthetic drug related to the hormone vasopressin, which is secreted by the pituitary gland. Vasopressin appears to increase a person" s motivation and enjoyment of learning, and these are important factors in improving one" s memory. Taken in the form of a nasal spray, DDAVP has significantly increased subjects" ability to recall information on cue. Another hormone, epinephrine, may also aid memory. Gold and Delaney(1981)discovered that the memory-enhancing effects of epinephrine were greatest when it was administered right after a learning session. Delays in administering the epinephrine markedly reduced its effectiveness. These results suggest that naturally occurring memory problems may be due in part to inadequate levels of vasopressin or epinephrine(McGaugh, 1983).

单选题Inhaling pure oxygen for 30 seconds can double your recall of what happens in the next couple of minutes, according to researchers who addressed the annual meeting of the British Psychological Society in London this week. They say the effect lasts for 24 hours. The stimulating influence of oxygen is well-established folk wisdom among professions with access to the gas. Pilots sometimes pass the time by trying to memorise lists of passengers" names and where they are seated, and an oxygen boost makes the task easier, says Andrew Scholey, a psychologist at the University of Northumbria in Newcastle upon Tyne. Now Scholey and his colleague Mark Moss say they have conclusively shown in six controlled trials that oxygen significantly improves short-term memory, reaction time and attentiveness. A mask supplied some participants with pure oxygen and the others with ordinary air, which is about 20 percent oxygen. Neither group knew which type of gas they were inhaling. The volunteers then listened to a series of 15 words. Six minutes later they were asked to remember as many of the words as possible. The participants who inhaled air remembered only 4 or 5 words - but those who imbibed oxygen recalled 8 or 9. Too little or too much oxygen will not have the desired effect, the researchers discovered. The optimal exposure time ranges from 30 seconds to a minute, they say. And since the oxygen only lasts a couple of minutes in the body before it reacts with other molecules, volunteers have to be exposed to information soon after inhaling, though the improved recall can last up to 24 hours, says Scholey. So, should cramming students be sniffing oxygen instead of bingeing on caffeine? Probably not, since high levels of oxygen damage living tissue. Scholey thinks that oxygen-enriched study chambers will remain science fiction. "The only advice I have is not to revise at the top of a mountain." And as the festive season gets into full swing, the experience of deep-sea divers may be especially useful. "Divers have told me they have a blast of oxygen to get rid of hangovers," Scholey says. But he warns enthusiasts not to try it at home.

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Imagine waking up and finding the value of your assets has been halved. No, you"re not an investor in one of those hedge funds that failed completely. With the dollar slumping to a 26-year low against the pound, already-expensive London has become quite unaffordable. A coffee at Starbucks, just as unavoidable in England as it is in the United States, runs about $8. The once all-powerful dollar isn"t doing a Titanic against just the pound. It is sitting at a record low against the euro and at a 30-year low against the Canadian dollar. Even the Argentine peso and Brazilian real are thriving against the dollar. The weak dollar is a source of humiliation, for a nation"s self-esteem rests in part on the strength of its currency. It"s also a potential economic problem, since a declining dollar makes imported food more expensive and exerts upward pressure on interest rates. And yet there are substantial sectors of the vast U.S. economy — from giant companies like Coca-Cola to mom-and-pop restaurant operators in Miami—for which the weak dollar is most excellent news. Many Europeans may view the U.S. as an arrogant superpower that has become hostile to foreigners. But nothing makes people think more warmly of the U.S. than a weak dollar. Through April, the total number of visitors from abroad was up 6.8 percent from last year. Should the trend continue, the number of tourists this year will finally top the 2,000 peak? Many Europeans now apparently view the U.S. the way many Americans view Mexico — as a cheap place to vacation, shop and party, all while ignoring the fact that the poorer locals can"t afford to join the merrymaking. The money tourists spend helps decrease our chronic trade deficit. So do exports, which thanks in part to the weak dollar, soared 11 percent between May 2006 and May 2007. For first five months of 2007, the trade deficit actually fell 7 percent from 2006. If you own shares in large American corporations, you"re a winner in the weak-dollar gamble. Last week Coca-Cola"s stick bubbled to a five-year high after it reported a fantastic quarter. Foreign sales accounted for 65 percent of Coke"s beverage business. Other American companies profiting from this trend include McDonald"s and IBM. American tourists, however, shouldn"t expect any relief soon. The dollar lost strength the way many marriages break up — slowly, and then all at once. And currencies don"t turn on a dime. So if you want to avoid the pain inflicted by the increasingly pathetic dollar, cancel that summer vacation to England and look to New England. There, the dollar is still treated with a little respect.

单选题Smoking causes wrinkles by upsetting the body" s mechanism for renewing skin, say scientists in Japan. Dermatologists say the finding confirms the long-held view that smoking ages skin prematurely. Skin stays healthy and young-looking because of a fine balance between two processes that are constantly at work. The first breaks-down old skin while the second makes new skin. The body breaks down the old skin with enzymes called matrix metalloproteinases, or MMPs, They chop up the fibers that form collagen(胶原质)—the connective tissue that makes up around 80 percent of normal skin. Akimichi Morita and his colleagues at Nagoya City University Medical School suspected that smoking disrupted the body" s natural process of breaking down old skin and renewing it. To test their idea, they first made a solution of cigarette smoke by pumping smoke through a saline(盐的)solution. Smoke was sucked from cigarettes for two seconds every minute. Tiny drops of this smoke solution were added to dishes of human fibroblasts, the skin cells that produce collagen. After a day in contact with smoke solution, the researchers tested the skin cells, to see how much collagen-degrading MMP they were making. Morita found that cells exposed to cigarette smoke had produced far more MMP than normal skin cells. Morita also tested the skin cells to see how much new collagen they were producing. He found that the smoke caused a drop in the production of fresh collagen by up to 40 percent. He says that this combined effect of degrading collagen more rapidly and producing less new collagen is probably what causes premature skin ageing in smokers, in both cases, the more concentrated the smoke solution the greater the effect on collagen. " This suggests the amount of collagen is important for skin ageing," he says. "It looks like less collagen means more wrinkle formation". Morita doesn" t know if this is the whole story of why smokers have more wrinkles. But he plans to confirm his findings by testing skin samples from smokers and non-smokers of various ages to see if the smoking has the same effect on collagen. "So far we" ve only done this in the lab. " he says. " We don"t know exactly what happens in the body yet that might take some time. " Other dermatologists are impressed by file work. "This is fascinating," says Lawrence Parish. Director of the Centre for International Dermatology at Thomas Jefferson University Hospital in Philadelphia. This confirms scientifically what we"ve long expected, he says. "Tobacco smoke is injurious to skin. "

单选题The bird flu virus is mutating and becoming more dangerous to mammals, according to researchers. The discovery reinforces fears that a human pandemic of the disease could yet occur. Avian flu hit the headlines in 1997 when a strain called H5N1 jumped from chickens to people, killing 6 people in Hong Kong. Within 3 days, the country"s entire chicken population was slaughtered and the outbreak was controlled. Since then new strains of virus have emerged, killing a further 14 people. As yet, no strain has been able to jump routinely from person to person. But if a more virulent strain evolves, the fear is that it could trigger widespread outbreaks, potentially affecting millions of people. Now, genetic and animal studies show that the virus is becoming more menacing to mammals. Immediate action is needed to stem the virus"s transmission, says Hualan Chen from Harbin Veterinary Research Institute, China, who was involved in the research. Chen and colleagues studied 21 H5N1 flu virus samples taken from apparently healthy ducks, which act as a natural reservoir for the disease, in southern China between 1999 and 2002. The researchers inoculated groups of chickens, mice and ducks with virus samples taken from different years and waited to see which animals became ill. Their results are presented this week in the Proceedings of the National Academy of Sciences. As expected, ducks were immune to the virus"s effects and the chickens fell sick. However, the mice also became ill, losing weight and the use of their limbs. Crucially, the severity of their illness was linked with the year from which the virus sample was taken. Viruses isolated in 2001 and 2002 made the animals more ill than those isolated earlier on. The findings hint that some time around 2001, the virus became adept at infecting mammals. Genetic analysis of the same samples reveals that the virus"s DNA changed over that time, suggesting that accumulated mutations may have contributed to the increased virulence. Researchers are concerned that a virus that has acquired the ability to infect mice could also infect humans. "The disease could resurge at any time," warns virologist Marion Koopmans from the National Institute of Public Health and the Environment in Bilthoven, the Netherlands. The findings highlight the need for improved surveillance to ensure that any future outbreaks are curtailed, she says. Although domestic poultry are easily culled, wild animals are more difficult to contain. "It is impossible to eradicate the natural reservoir," says Koopmans, "so we need to learn to live with it." Birds may not be the only villains in this story, however. Chen believes that pigs may also play a part. In Asia, chickens and pigs are often kept in close proximity, so the virus may have shuffled back and forth between the 2 species, picking up mutations and becoming better at infecting mammalian hosts. Humans may then have caught the disease from swine.

单选题Gordon Shaw the physicist, 66, and colleagues have discovered what's known as the "Mozart effect", the ability of a Mozart sonata, under the right circumstances, to improve the listener's mathematical and reasoning abilities. But the findings are controversial and have launched all kinds of crank notions about using music to make kids smarter. The hype, he warns, has gotten out of hand. But first, the essence: is there something abut the brain cells work to explain the effect? In 1978 the neuroscientist Vernon Mountacastle devised a model of the neural structure of the brain's gray matter. Looking like a thick band of colorful bead work, it represents the firing patterns of groups of neurons. Building on Mounteastle, Shaw and his team constructed a model of their own. On a lark, Xiaodan Leng, who was Shaw's colleague at the time, used a synthesizer to translate these patterns into music. What came out of the speakers wasn't exactly toe-tapping, but it was music. Shaw and Leng inferred that music and brain-wave activity are built on the same sort of pattern. "Gordon is a contrarian in his thinking, " says his longtime friend, Nobel Prize-Winning Standford Physicist Martin Perl. "That's important. In new areas of science, such as brain research, nobody knows how to do it. " What do neuroscientists and psychologists think of Shaw's findings? They haven't condemned it, but neither have they confirmed it. Maybe you have to take them with a grain of salt, but the experiments by Shaw and his colleagues are intriguing. In March a team led by Shaw announced that young children who had listened to the Mozart sonata and studied the piano over a period of months improved their scores by 27% on a test of ratios and proportions. The control group against which they were measured received compatible enrichment course — minus the music. The Mozart-trained kids are now doing math three grade levels ahead of their peers, Shaw claims. Proof of all this, of course, is necessarily elusive because it can be difficult to do a double blind experiment of educational techniques. In a double blind trial of an arthritis drug, neither the study subjects nor the experts evaluating them know which ones got the best treatment and which a dummy pill. How do you keep the participants from knowing it's Mozart on the CD?

单选题My father was【C1】______ a strong man who loved being active, but a terrible illness【C2】______ all that away. Now he can no longer walk. And he must sit quietly in a chair all day. Even talking is【C3】______. One night, I went to visit him with my sisters, we started talking about life, and I told them about one of my【C4】______. I said that we must always give things up as we grow—our youth, our beauty, our friends—but it always【C5】______ that after we give something up, we gain something new in its place. Then suddenly my father spoke up. He said, "But, Peter. I gave up【C6】______! What did I gain?" I thought and thought, but I could not think of anything to say. 【C7】______ he answered his own question: "I gained the love of my family. " I looked at my sisters, and saw tears in their eyes, along with hope and thankfulness. I was also【C8】______ by his words. After that, when I began to fell irritated at someone, I would remember his words and become【C9】______ if he could replace his great pain with a feeling of love for others, then I should be able to give up my small irritations. In this way, I learned the power of acceptance from my father. Sometimes I【C10】______ what other things I could learned from him if I had listened more carefully when I was a boy. For now, though, I am grateful for this gift.

单选题Young discoverers need not despair—though there are few blanks left on today' s map of the world, there are still unexplored realms to be charted in the depths of the oceans, the most remote recesses of the rain forests and the furthest reaches of outer space. Some scientists speculate there maybe 10 million species—perhaps even 100 million—living on the ocean floor that are yet to be discovered. Recent research suggests that all told some 90% of the world' s plants and before they are even described and named(that is, if their habitats are not destroyed before they are even found). Given these remarkable statistics, it' s clear that the physical world still offers intrepid explorers new frontiers of discovery. In this section on recent discoveries of the world around us, TIME travels 500m beneath the surface of the Pacific Ocean with Bruce Robison as he encounters a new species of luminous "jelly ," we make our way deep into the world' s tropical rain forests, where more than half of all life-forms on the planet live; we look into outer space to examine the role asteroids may have played in mass extinctions of the past and the potential threat they pose to our own civilization; and we ask whether there is life—intelligent or otherwise—elsewhere in the universe. John Hemming, former director of London' s royal Geographical Society, arguably the world' s epicenter of exploration, defines an explorer as someone "who goes to the edge of knowledge and brings back something new. " The people profiled in this section fit that description perfectly. The discoveries they have brought back from their explorations form new pieces in the puzzle of how the world works. As the pieces fit together, we get a glimpse of what a strange and beautiful mosaic it is.