单选题 Cleaning up our air may have made us healthier. A new analysis shows that the number of storms falls when pollution rises, and increases when pollution drops. Further tightening of present pollution controls 'could reduce aerosols (气溶胶；悬浮颗粒) so quickly that we have record numbers of tropical storms for the next decade or two', says Nick Dunstone of the Met Office Hadley Centre in Exeter, UK. Earlier studies found no connection between storm numbers and aerosols' ability to cool the surface by scattering light in the open air. But aerosols also increase the brightness and lifetime of low-level marine clouds. When Nick Dunstone of the Met Office Hadley Centre in Exeter, UK, added this effect into his climate models, the simulated clouds cooled the surface more than expected. Historically, this cooling effect has been strongest in the north Atlantic. Cooling the north Atlantic reduces the energy available to power hurricanes. It also shifts rising and falling air currents further south, increasing wind shear in the Atlantic hurricane nursery. This extra wind shear tears nascent storms apart before they can gain strength. In this way, Dunstone says, changes in aerosol emissions appear to drive cyclical variations in north Atlantic tropical storms. These variations have long been attributed to natural variations in ocean circulation. Throughout the 20th century, aerosol emissions increased with industrialization and decreased in economic slumps. Tropical storms were frequent from the 1930s through to the 1950s, but rarer in the better economic times of the 1960s to mid-1990s. Then pollution controls reduced aerosol levels, and Atlantic hurricanes came roaring back, with 19 in 1995, a record 28 in 2005, and 19 in each of the past three years. Dunstone expects the increase to continue for another two decades. After that, global warming may begin to reduce the number of tropical storms, by warming the air and thus reducing the temperature difference between the sea surface and the atmosphere. It is not clear whether aerosols affect the intensity of storms.

单选题 Sign has become a scientific hot button. Only in the past 20 years have specialists in language study realized that signed languages are unique—a speech of the hand. They offer a new way to probe how the brain generates and understands language, and throw new light on an old scientific controversy: whether language, complete with grammar, is something that we are born with, or whether it is a learned behavior. The current interest in sign language has roots in the pioneering work of one rebel teacher at Gallaudet University in Washington, D.C., the world's only liberal arts university for deaf people. When Bill Stokoe went to Gallaudet to teach English, the school enrolled him in a course in signing. But Stokoe noticed something odd: among themselves, students signed differently from his classroom teacher. Stokoe had been taught a sort of gestural code, each movement of the hands representing a word in English. At the time, American Sign Language (ASL) was thought to be no more than a form of pidgin English (混杂英语). But Stokoe believed the 'hand talk' his students used looked richer. He wondered: Might deaf people actually have a genuine language? And could that language be unlike any other on Earth? It was 1955, when even deaf people dismissed their signing as 'substandard'. Stokoe's idea was academic heresy (异端邪说). It is 37 years later. Stokoe—now devoting his time to writing and editing books and journals and to producing video materials on ASL and the deaf culture—is having lunch at a café near the Gallaudet campus and explaining how he started a revolution. For decades educators fought his idea that signed languages are natural languages like English, French and Japanese. They assumed language must be based on speech, the modulation (调节) of sound. But sign language is based on the movement of hands, the modulation of space. 'What I said,' Stokoe explains, 'is that language is not mouth stuff—it's brain stuff.'

单选题 Beauty and Body Image in the Media A. Images of female bodies are everywhere. Women—and their body parts—sell everything from food to cars. Popular film and television actresses are becoming younger, taller and thinner. Some have even been known to faint on the set from lack of food. Women's magazines are full of articles urging that if they can just lose those last twenty pounds, they'll have it all—the perfect marriage, loving children, great sex, and a rewarding career. B. Why are standards of beauty being imposed on women, the majority of whom are naturally larger and more mature than any of the models? The roots, some analysts say, are economic. By presenting an ideal difficult to achieve and maintain, the cosmetic and diet product industries are assured of growth and profits. And it's no accident that youth is increasingly promoted, along with thinness, as an essential criterion of beauty. If not all women need to lose weight, for sure they're all aging, says the Quebec Action Network for Women's Health in its 2001 report. And, according to the industry, age is a disaster that needs to be dealt with. C. The stakes are huge. On the one hand, women who are insecure about their bodies are more likely to buy beauty products, new clothes, and diet aids. It is estimated that the diet industry alone is worth anywhere between 40 to 100 billion (U. S.) a year selling temporary weight loss (90% to 95% of dieters regain the lost weight). On the other hand, research indicates that exposure to images of thin, young, air-brushed female bodies is linked to depression, loss of self-esteem and the development of unhealthy eating habits in women and girls. D. The American research group Anorexia Nervosa Related Eating Disorders, Inc. says that one out of every four college-aged women uses unhealthy methods of weight control—including fasting, skipping meals, excessive exercise, laxative (泻药) abuse, and self-induced vomiting. The pressure to be thin is also affecting young gifts: the Canadian Women's Health Network warns that weight control measures are now being taken by girls as young as 5 and 6. American statistics are similar. Several studies, such as one conducted by Marika Tiggemann and Levina Clark in 2006 titled 'Appearance Culture in 9- to 12-Year-Old Girls: Media and Peer Influences on Body Dissatisfaction, ' indicate that nearly half of all preadolescent girls wish to be thinner, and as a result have engaged in a diet or are aware of the concept of dieting. In 2003, Teen magazine reported that 35 percent of girls 6 to 12 years old have been on at least one diet, and that 50 to 70 percent of normal weight girls believe they are overweight. Overall research indicates that 90% of women are dissatisfied with their appearance in some way. Media activist Jean Kilbourne concludes that, 'Women are sold to the diet industry by the magazines we read and the television programs we watch, almost all of which make us feel anxious about our weight. ' E. Perhaps the most disturbing is the fact that media images of female beauty are unattainable for all but a very small number of women. Researchers generating a computer model of a woman with Barbie-doll proportions, for example, found that her back would be too weak to support the weight of her upper body, and her body would be too narrow to contain more than half a liver and a few centimeters of bowel. A real woman built that way would suffer from chronic diarrhea (慢性腹泻) and eventually die from malnutrition. Jill Barad, President of Mattel (which manufactures Barbie), estimated that 99% of girls aged 3 to 10 years old own at least one Barbie doll. Still, the number of real life women and girls who seek a similarly underweight body is epidemic, and they can suffer equally devastating health consequences. In 2006 it was estimated that up to 450, 000 Canadian women were affected by an eating disorder. F. Researchers report that women's magazines have ten and one-half times more ads and articles promoting weight loss than men's magazines do, and over three-quarters of the covers of women's magazines include at least one message about how to change a woman's bodily appearance—-by diet, exercise or cosmetic surgery. Television and movies reinforce the importance of a thin body as a measure of a woman's worth. Canadian researcher Gregory Fouts reports that over three-quarters of the female characters in TV situation comedies are underweight, and only one in twenty are above average in size. Heavier actresses tend to receive negative comments from male characters about their bodies ('How about wearing a sack?'), and 80 percent of these negative comments are followed by canned audience laughter. G. There have been efforts in the magazine industry to buck (抵制，反抗) the trend. For several years the Quebec magazine Coup de Pouce has consistently included full-sized women in their fashion pages and Chatelaine has pledged not to touch up photos and not to include models less than 25 years of age. In Madrid, one of the world's biggest fashion capitals, ultra-thin models were banned from the runway in 2006. Furthermore Spain has recently undergone a project with the aim to standardize clothing sizes through using a unique process in which a laser beam is used to measure real life women's bodies in order to find the most true to life measurement. H. Another issue is the representation of ethnically diverse women in the media. A 2008 study conducted by Juanita Covert and Travis Dixon titled 'A Changing View: Representation and Effects of the Portrayal of Women of Color in Mainstream Women's Magazines' found that although there was an increase in the representation of women of colour, overall white women were overrepresented in mainstream women's magazines from 1999 to 2004. I. The barrage of messages about thinness, dieting and beauty tells 'ordinary' women that they are always in need of adjustment—and that the female body is an object to be perfected. Jean Kilboume argues that the overwhelming presence of media images of painfully thin women means that real women's bodies have become invisible in the mass media. The real tragedy, Kilbourne concludes, is that many women internalize these stereotypes, and judge themselves by the beauty industry's standards. Women learn to compare themselves to other women, and to compete with them for male attention. This focus on beauty and desirability 'effectively destroys any awareness and action that might help to change that climate. '

单选题 When researcher Josh Santarpia stands at the foot of a bed, taking measurements with a device that can detect tiny, invisible particles of saliva (唾液) that come out of someone's mouth and move through the air, he can tell whether the sick person is speaking or not just by looking at the read-out on his instrument. 'So clearly, the particles which that person is putting out are being breathed in by someone that is five feet away from them, at the foot of their bed,' says Santarpia, who studies biological aerosols (气溶胶) at the University of Nebraska Medical Center. 'Do they contain vires? I don't know for sure.' He and his colleagues are doing their best to find out. Already, using another device that looks like a fancy dust collector, they've sucked up air samples from 11 isolation rooms that housed 13 people who tested positive for COVID-19 infection, all of whom had a variety of mild symptoms. In those air samples, researchers found the genetic fingerprint of the virus. 'It was more than half of the samples that we took. It was fairly everywhere,' says Santarpia, 'but the concentrations were really pretty low.' Finding the genetic material doesn't necessarily mean that there's living virus that could potentially make someone sick, he cautions. Some primary evidence indicates that this might be the case, but the team wants to do more work 'and try and be as certain as we possibly can whether or not certain samples had infectious virus in them or not.' They want to know that with a high degree of confidence because the question of whether or not the coronavirus (冠状病毒) can be transported by the air is extremely controversial right now—and it's a question that has real implications for what people should do to avoid getting infected. 'I personally think that transmission by breathing in virus in the air is happening,' says Linsey Marr, an aerosol scientist at Virginia Tech. But she says so far, health experts have largely discounted the possibility of transmitting this coronavirus in this way.

单选题 If the salinity of ocean waters is analyzed, it is found to vary only slightly from place to place. Nevertheless, some of these small changes are important. There are three basic processes that cause a change in oceanic salinity. One of these is the subtraction of water from the ocean by means of evaporation—conversion of liquid water to water vapor. In this manner, the salinity is increased, since the salts stay behind. If this is carded to the extreme, of course, white crystals of salt would be left behind. The opposite of evaporation is precipitation, such as rain, by which water is added to the ocean. Here the ocean is being diluted so that the salinity is decreased. This may occur in areas of high rainfall or in coastal regions where rivers flow into the ocean. Thus salinity may be increased by the subtraction of water by evaporation, or decreased by the addition of fresh water by precipitation or runoff. Normally, in tropical regions where the sun is very strong, the ocean salinity is somewhat higher than it is in other parts of the world where there is not as much evaporation. Similarly, in coastal regions where rivers dilute the sea, salinity is somewhat lower than in other oceanic areas. A third process by which salinity may be altered is associated with the formation and melting of sea ice. When seawater is frozen, the dissolved materials are left behind. In this manner, seawater directly beneath freshly formed sea ice has a higher salinity than it did before the ice appeared. Of course, when this ice melts, it will tend to decrease the salinity of the surrounding water. In the Weddell Sea, off Antarctica, the densest water in the oceans is formed as a result of this freezing process, which increases the salinity of cold water. This heavy water sinks and is found in the deeper portions of the oceans of the world.

单选题 Dare to Dream A. Dreams may affect our lives (and vice versa) more than we ever realized, says groundbreaking new research. Dream is a way for the subconscious to communicate with the conscious mind. Dreaming of something you are worried about, researchers say, is the brain's way of helping you get prepared for a disaster in case it occurs. Dreaming of a challenge, for example giving a presentation at work or playing sports, can enhance your performance. And cognitive (认知的) neuroscientist have discovered that dreams and the rapid eye movement (REM) that happens while you are dreaming are linked to our ability to learn and remember. B. Dreaming is a 'mood regulatory system,' says Dr. Cartwright, chairman of the psychology department at Rush University Medical Center in Chicago. She has found that dreams help people work through the day's emotional ups and downs. It's like having a built-in therapist. While we sleep, dreams compare new emotional experience to old memories. As she puts it, 'you may wake up and think, what was Uncle Harry doing in my dream? I haven't seen him for 50 years. But the old and new images are emotionally related.' It's the job of the conscious mind to figure out the relationship. C. In fact, dream emotions can help real therapists treat patients undergoing traumatic(创伤性) life events. In a new study of 30 recently divorced adults, Cartwright tracked their dreams over a 5-month period, measuring their feelings toward their ex-spouses. She discovered that those who were angriest at the spouse while dreaming had the best chance of successfully coping with divorce. If their dreams were calm, they hadn't started to work through their emotions and deal with the divorce. For therapists, this finding will help to determine whether divorced men or women need counseling or have already dreamed their troubles away. D. No device lets researchers read the content of dreams while we sleep, but scientistsare finding new ways to interpret once we have awakened. Forget Sigmund Freud's notion that dreams contain images with universal meanings for all his undeniable authority in the field of dream interpretation. A new generation of psychologistsinsists that dream symbols differ depending on the dreamer. In a recent study, Joseph Konick, a psychology professor at the University of Ottawa in Canada, asked 13 volunteers to make two lists: one of details recalled from recent dreams, and another of recent events in their waking lives. When analysts were asked to match which volunteer experienced which dream, they failed. Koninck's conclusion: Each person understands his or her dreams better than anyone else including traditional psychoanalysts. 'There's just no evidence of universal dream symbols, ' says Koninck. 'My advice is to throw away your dream dictionary if you really want to interpret your dreams. ' E. A century after the Freud era, scientists are only now decoding the biology of we manufacture dreams. At the sleep Research Program at the University of Pittsburgh Medical Center, Dr. Nofzinger 'looks into' the brains of sleeping subjects using PET scans normally employed to detect cancer and other diseases. By injecting subjects with a mildly radioactive substance, he has traced the source of the brain that controls emotions. During dreaming, the limbic system explodes like fireworks with neural (神经的) activity, filling our dreams with drama. 'That's why so many dreams are emotional states,' saysNofzinger, 'where we are running from danger or facing an anxious situation. The part of the brain that controls dreams also manages our instincts, drives, sexual behavior and fight-or-flight response.' That's why dreams are often strange combinations of events and people. F. For 11 years, a 58-year-old anthropologist (人类学家) kept a journal of nearly 5000 dreams. By analyzing color patterns in the dreams, Arizona-based researcher Robert Hoss could accurately predict certain things about the man's emotional state. Hoss correctly identified two separate years when the man experienced crises in his life. The anthropologist confirmed that in 1997 he had clashed with a colleague over a management issue, and in 2003 he'd had a falling out with a friend that left deep emotional scars. G. Today, psychologists are applying modern technology to probe the content of dreams. Hoss uses a computer-based approach called content analysis to interpret the colors in dreams. More than 80 percent of people dream in color, he says, though only a quarter of them recall the shades the next morning. To collect data, he analyzed nearly 24, 000 dreams, catalogued in two databases. His study suggested that specific colors represent particular emotions. For example, red means action, excitement and desire; blue equals calmness and harmony; black hints fear, anxiety and intimidation. The clues are in the colors. Hoss has been trying to determine the emotional states of a dreamer based on his/her dream colors. But, as with symbols and action, one size doesn't fit all when it comes to interpretation. Using color is your brain's way of painting dreams with your emotion, and different people have different ways of using color. H. Psychologists have long known that people can solve their problems at work and home by 'sleeping on it.' The challenge has always been to train yourself to dream up the solutions. Dr. Barret, editor of the journal Dreaming, advises individuals to consider questions just before falling asleep (Should I take this job? Should I marry this guy?), and then let the subconscious provide the answers. 'I've known artists looking for inspiration who simply dream up a future show of their art and wake up with plenty of new painting ideas,' says Barrett. 'More and more people are learning these techniques to control their dreams.' I. Some researchers believe you can guide your dreams while you are sleeping. In recent years, Stephen LaBerge, PhD, has pioneered a way of directing the sleeping mind through 'lucid dreaming,' in which a sleeping person realizes he/she is dreaming while it is happening. Lucid dreamers can experience fantasy adventures like flying to the moon, traveling through time or making love on a beach—while fully aware that they are dreaming. According to La Berge, lucid dreamers can use the experience for a variety of purposes, problem solving, developing creative ideas and healing. Patricia Keelin, a 55-year-old photographer has used lucid dreaming for everything from talking to her long-dead father to feasting on sweets. 'Chocolate always tastes better in lucid dreams since you don't have to worry about calories, 'she says 'Lucid dreaming is great and exciting, because it's free and available to everybody.' J. Well, not entirely free. Although everyone has the potential to dream lucidly, it rarely happens routinely without special training. Instructional workshops are needed to help individuals participate in their dreams. If you have repeating nightmares that make it difficult to sleep, try to change the endings. Once you awaken from a bad dream, imagine a change in the action to create a more positive outcome. If you are trapped, try to fly. In you dream, you can do what you want. Indeed, your dreams are like private movies where you are the star, director and writer all at once. And as the latest research indicates, you are also the most insightful movie critic. The best interpreter of your dreams is you.

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单选题 Google researchers have used artificial intelligence (AI) to teach robots how to move like real animals (in this case, dogs). They describe their experiment in a blog released this week. 'First, we describe how robots can learn to move like a real animal by imitating their motions, producing fast and fluent movements like running slowly and hopping. Then, we discuss a system for automating the training of moving skills in the real world, which allows robots to learn to walk on their own, with minimal human assistance,' shared in the blog Xue Bin (Jason) Peng, Student Researcher and Sehoon Ha, Research Scientist, Robotics at Google. They achieved this impressive feat by using something called reinforcement learning (RL). They began by taking a reference video recorded from an animal and using RL to get the robot to imitate an animal's movement. 'By providing the system with different reference motions, we are able to train an animal-shaped robot to perform a diverse set of agile behaviors, ranging from fast walking to dynamic hops and turns. The policies are trained primarily in simulation(模拟，模仿), and then transferred to the real world using a space adaptation technique that can efficiently adapt a policy using only a few minutes of data from the real robot,' wrote the researchers in their blog. However, it is a well-known fact that simulators provide a poor approximation of the real world, meaning that simulations don't perform well in reality. This is where the researchers decided to use a sample-efficient space adaptation technique. They did so by introducing an element of randomness to the physical parameters(参数) used in the simulation by varying physical quantities, such as the robot's mass and friction. This resulted in a machine learning model that could account for all kinds of small changes and the complications they create. The end result is a robot that moves like a real dog. This kind of work is crucial as it can open opportunities to use robots to do sophisticated tasks in the real world.