2019年医学博士外语真题试卷

Directions: In this section there is a passage with ten numbered blanks. For each blank, there are four choices marked A, B, C and D on the right side.Choose the best answer and mark the letter of your choice on theANSWER SHEET.

We spend a lot of time looking at the eyes of others for social_51_—it helps us understand a person’s emotions, and make decisions about how to respond to them. We also know that adults avoid eye contact when anxious. But researchers have known far_52_about eye gazing patterns in children.

According to new research by Kalina Michalska, assistant professor of psychology at the University of California,Riverside, we now know that anxious children tend to avoid making eye contact, and this has consequences for how they experience fear. The_53_and less frequently they look at the eyes of others, the more likely they are to be afraid of them, even when there may be no reason to be. Her study,”Anxiety Symptoms and Children’s Eye Gaze During Fear Learning”, was published in the journalThe Journal of Child Psychology and Psychiatry.

“Looking at someone’s eyes helps us understand whether a person is feeling sad,angry, fearful, or surprised. As adults, we then make decisions about how torespond and what to do next. But,we know much less about eye patterns in children—so, understanding thosepatterns can help us learn more about the development of social learning,” Michalska said.

Michalska and the team of researchers showed 82 children, 9 to 13 years old, images of two women’s faces on a computer screen. The computer was equipped with an eye tracking device that allowed them to measure_54_onthe screen children were looking, and for how long. The participants were originally shown each of the two women a total of four times. Next, one of the images was_55_with a loud scream and a fearful expression, and the other one was not. At the end, children saw both faces again without any sound or scream.
The following three conclusions can be drawn from the study:

1 . All children spent more time looking at the eyes of a face that was paired with the loud scream than the face that was not paired with the scream,_56_they pay attention to potential threats even in theabsence of outward cues.

2 . Children who were more anxious avoided eye contact during all three phases of the experiment, for both kindsof faces. This had consequences for how afraid they were of the faces.

3 . The more children avoided eye contact; the more afraid they were_57_the faces.

The conclusions suggest that children spend more time looking at the eyes of a faces when previously paired with something frightening suggesting they pay more attention to potentially threatening information as a way to learn more about the situation and plan what to donext.

However, anxious children tend to avoid making eye contact, which leads to greater_58_experience. Even though avoiding eye contact may reduceanxiety_59_, the study finds that—over time—children may be missing out_60_important social information.This includes that a person may no longer be threatening or scary, and yet the child continues feeling fearful of that person.

The British psychoanalyst John Bowlby maintains that separation from the parents during the Sensitive “attachment” period from birth to three may scar a child’s personality and predispose to emotional problems in later life.

Some people have drawn the conclusion from Bowlby’s work that children should not be subjected to day care before the age of three because of the parental separation it entails,and many people do believe this. It has been argued that an infant under three who is cared for outside the home may suffer because of the separation from his parents. But there are also arguments against such a strong conclusion.

But traditional societies are so different from modern societies that comparisons based on just one factor are hard to interpret. Firstly, anthropologists point out that the insulated love affair between children and parents formed in modern societies does not usually exist in traditional societies. For example, insome tribal societies, such as the Ngoni, the father and mother of a child did not rear their infant alone—far from it.

Certainty, Bowlby’s analysis raises the possibilities that early day care had delayed effects. The possibility thatsuch care might lead to, say, more mental illness or crime 15 or 20 years later can only explored by the use of statistics. However, statistical studies of this kind have not yetbeen carried out, and even if they were, the results would certainly be complicated and controversial. Secondly, common sense tells us that day care would not be so widespread today if parents,care-takers found children had problems with it. Thirdly, in the last decade, there have been a number of careful American studies of children in day care, and they have uniformly reported that care had a neutral or slightly positive effect on children’s development.

Whateverthe long-term effects, parents sometimes find the immediate effects difficult to dealwith.Children under three are likely to protest at leaving theirparents and show unhappiness. At the age of three or three and a half almost all children find the transition to nursery easy,and this is undoubtedly why more and moreparents make use ofchildcareat this time.The matter,then,is far from clear-cut,thoughexperience and available evidence indicate early care is reasonable for infants.

By the end of this century, the average world temperature is expected to increase between one and four degrees,with widespread effects on rainfall,sea levels and animal habitats. But in the Arctic,where the effects of climate change are most intense, the rise in temperature could betwice as much.

Understanding how Arctic warming will affect the people,animals,plant and marine life and economic activity in Canada’s North are important to the country’s future, says Kent Moore,an atmospheric physicist at University of Toronto Mississauga whois participating ina long-term,international study of the marine ecosystem along the Beaufort Sea. from Alaska to the Mackenzie delta.

The studywill add to our knowledge of everything from the extent of seaice inthe region to howfish stocks will change to which areas could become targetsforoiland gas explorationto the impact on the indigenous people who call this part of the countryhome.

Moore,who has worked in the Arctic for more than 20 years,sayshisresearch has already found that thinning sea ice and changes in wind patterns are causing an importantchange in the marine food chain;phytoplankton（浮游植物）is blooming two tothree weeks earlier. Many animals time their annual migration to the Arctic for when food is plentiful,and have not adapted to the earlier bloom.”‘Animals’behavior can evolve over a long time, but these climate changes are happening in the space of adecade,rather than hundreds of years,” says Moore,”Animals can’t change their behavior that quickly. “

A warmer Arctic is expected to have importanteffects on human activity in the region,as the Northwest Passage becomes navigableduring the summer,and resource extraction becomes more feasible. Information gained from the study will help government,industry and communities make decisions about resource management,economic development and environmental protection.

Moore says the study—whichinvolves Canadian,American and European researchers and governmentagencies willalso use a novel technology to gather atmospheric data: remotely piloted drones. “The drones have the capability of a large research aircraft,and they’re easierto deploy,”he says,showing the researchers to gather information on a moreregular basisthan they would be able to with piloted aircraft.

Having too much caffeine during pregnancy may impair baby’ liver development and increase the risk of liver disease in adulthood, according to a studypublished in the Journal of Endocrinology. Pregnant rats given caffeine had offspring with lower birth weights, altered growth and stress hormone levels and impaired liver development. The study findings indicate that consumption of caffeine equivalent to 2-3 cups of coffee may alter stress and growth hormone levels in a manner that can impair growth and development, and increase the risk of liver disease in adulthood.

Previous studies have indicated thatprenatal caffeine intake of 300 mg/day or more in women, which is approximately 2 to 3cups coffee per day, can result in lower birth weights of their children. Animal studies havefurther suggested that prenatal caffeine consumption may have more detrimental long-term effects on liver development with an increased susceptibility to non-alcoholicfatty liver disease, a debilitating condition normally associated with obesity and diabetes. However, the underlying link between prenatal caffeine exposure and impaired liver development remains poorly understood. A better understanding of how caffeine mediates these effects could help prevent these health issues in people in the future.

In this study, Prof Hui Wang and colleagues at Wuhan University in China, investigated the effects of low (equivalent to 2-3 cups of coffee) and high doses (equivalent of 6-9cups of coffee) caffeine, given to pregnant rats,on liver function and hormone levels of their offspring. Offspring exposed to prenatal caffeine had lower level of the liver hormone, insulin like growth factor(IGF-1), and higher levels of the stress hormone, corticosteroid at birth. However, liver development after birth showed a compensatory ‘catch up’ phase,characterized by increased levels of IGF-1,which is important for growth.

Dr. Yinxian Wen, study co-author, says,”Our results indicate that prenatal caffeine causes an excess of stress hormone activity in the mother, which inhibits IGF-1 activity for liver development before birth. However,compensatory mechanisms do occur after birth to accelerate growth and restore normal liver function, as IGF-1 activity increases and stress hormone signalling decreases. The increased risk of fatty liver disease caused by prenatal caffeine exposure is mostlikely a consequence of this enhanced, compensatory postnatal IGF-1 activity.”

These findings not only confirm thatprenatal caffeine exposure leads to lower birth weight and impaired liver development before birth but also expand our current understanding of the hormonal changes underlying these changes and suggest the potential mechanism for increased risk of liver disease in the future. However, these animal findings need to be confirmed in humans.

Dr. Wen comments,”Our work suggests that prenatal caffeine is not good for babies and although these findings still need to be confirmed in people, I would recommend that women avoid caffeine during pregnancy.”

The bizarre antics of sleepwalkers have puzzled police,perplexed scientists,and fascinated writers for centuries. There is an endless supply of stories about sleepwalkers.Persons have been said to climb on steep roofs,solve mathematical problems, compose music,walk through plate-glass windows,andcommit murder in their sleep.

How many of these stories have a basis in fact,and howmany are pure fakery?No one knows, but if some of the most sensational stories shouldbe taken with a barrel of salt, others are a matter of record.

In Revere,Massachusetts,a hundred policemencombed a waterfront neighborhood for alost boy who left his home in his sleep inandwoke up five hours later on a strange sofa in a strange living room,withnoidea how he had got there.

There is an early medical record of asomnambulist who wrote a novel in his sleep. And the great French writer Voltaire knewa sleepwalker who once got out of bed,dressed himself, made a polite bow,danced a minuet,and then undressed and went back to bed.

At the University of Iowa,astudent was reported to have the habit of getting up in the middle of the night and walking three-quarters of a mile to the Iowa River.He would take a swim and then go back to his room to bed.

The world’s champion sleepwalker was supposed to have been an Indian,Pandit Ramrakha,whowalked sixteen miles along a dangerous road without realizing that he had left hisbed.Second in line for the title is probably either a Vienna housewife or a British farmer.The woman did all her shopping on busy streets in her sleep. Thefarmer, in his sleep,visited a veterinarian miles away.

The leading expert on sleep in America claims that he has never seen a sleepwalker.He isDr. Nathaniel Kleitman, a physiologist at the Universityof Chicago.He is saidto knowmore about sleep than any other living man,and during thelastthirty-five yearshad lost a lot of sleep watching people sleep. Says he,”Of course,I know that there aresleepwalkers because I have read about them in the newspapers. But none of mysleepers ever walked,and ifI were to advertise for sleepwalkers for an experiment,I doubt that I’d get many takers.”

Sleepwalking, nevertheless,is ascientific reality. Like hypnosis,it is one of those dramatic, eerie,awe-inspiring phenomena that sometimes border on the fantastic. It lends itself to controversy and misconceptions,what is certain about sleepwalking is that it is a symptom of emotional disturbance, and that the only way to cure it is to remove the worries and anxieties that cause it.Doctors saythat somnambulism is much more common than is generally supposed. Some have estimated that there are four million somnambulists in the United States. Others set the figure even higher. Many sleepwalkers do not seek help and so are never put on record,which means that an accurate count can never be made.

The simplest explanationof sleepwalking is that it is the acting out of a vivid dream. The dream usuallycomesfrom guilt, worry, nervousness, or some other emotional conflict. The classicsleepwalker is Shakespeare’s Lady Macbeth.Her nightly wanderings were caused by herguilty consience at having committed murder.Shakespeare said of her,”The eyes are open but their sense is shut.”

Theage-oldquestion is: Is the sleepwalker actually awake or asleep? Scientists have decided that he is about half-and-half.Like Lady Macbeth,he has weighty problems onhismind,Dr,Zeida Teplitz,who made a ten-year study of the subject,says,”Some people stay awake all night worrying about their problems. The sleepwalker thrashes them out in his sleep. He is awake in the muscular area,partially asleep in thesensory area.”In other words, a person can walk in his sleep, move around,and do other things,but he does not think about what he is doing.

Beyond the basic animal instincts to seek food and avoid pain, Freud identified two sources of psychic energy, which he called “drives”: aggression and libido. The key to his theory is that these were unconscious drives,shaping our behavior without the mediation of our waking minds; they surface, heavily disguised, only in our dreams. The work of the past half-century in psychology and neuroscience has been to downplay the role of unconscious universal drives,focusing instead on rational processes in conscious life. But researchers have found evidence that Freud’s drives really do exist, and they have their roots in the limbic system,a primitive part of the brain that operates mostly below the horizon of consciousness. Now more commonly referred to as emotions, the modern suite of drives comprises five: rage, panic, separation distress, lust and a variation on libido sometimes called seeking.

The seeking drive is proving a particularly fruitful subject for researchers. Although like theothers it originates in the limbic system, it also involves parts of the forebrain; the seatof higher mental functions. In the 1980s, Jaak Panksepp, a neurobiologist at Bowling Green State University in Ohio, became interested in a place near the cortex known as the ventral tegmental area, which in humans lies just above the hairline.When Panksepp stimulated the corresponding region in a mouse, the animal would sniff the air and walk around, as though it were looking for something. Was it hungry? No. The mouse would walk right by a plate of food, or for that matter any other object Paksepp could think of. This brain tissue seemed to cause ageneral desire for something new.”What I was seeing,” he says,”was the urgeto do stuff.” Panksepp called this seeking.

To neuropsychologist Mark Solms of University College in London, that sounds very much like libido.”Freud needed some sort of general, appetitive desire to seek pleasure in the world of objects,” says Solms. Panksepp discovered as a neuroscientist what Freud discovered psychologically.” Solms studied the same region of the brain for his work on dreams. Since the 1970s,neurologists have known that dreaming takes place during a particular form of sleep known as REM—rapid eye movement—which is associated with a primitive part of the brainknown as the pons. Accordingly,they regarded dreaming as a low-level phenomenon of no great psychological interest. When Solms looked into it, though, itturned out that the key structure involved in dreaming was actually the ventral tegmental, the same structure that Panksepp had identified as the seatof the “seeking” emotion. Dreams, it seemed, originate with the libido— which is just what Freud had believed.

Freud’s psychological map may have been flawed in many ways, but it also happens to be the most coherent and, from the standpoint of individual experience, meaningful theory ofthe mind. “Freud should be placed in the same category as Darwin, who lived before the discovery of genes,” says Panksepp. “Freud gave us a vision of a mental apparatus. We need to talk about it, develop it, test it.” Perhaps it’s not amatter ofproving Freud wrong or right, but of finishing the job.

Scientists have a duty to talk to the public. Why? Because social policies need to be decided on the basis of rational grounds and facts. These include important issue ranging from climate change, to the goals of the space program,to the protection of endangered species, to the use of embryonic stem cells or animals in biomedical research. Both the public and policy makers need to understand not only the scientific justification for our work but also, in some cases, why we deem our studies to be morally justifiable.

The time is ripe for a more open, public and honest debate about the role of scientific experimentation in animals. What follows are some of my thoughts on this topic. I hope this perspective encourages other scientists tojoin the discussion and prompts opponents of animal research to create an atmosphere where civil discourse can take place, free of the threats，harassment and intimidation（恐吓）that are increasingly directed at biomedical scientists and their families.

Criticism to the use of animals in biomedical research rests on varied scientific and ethical arguments. One extreme view holds that information gathered from animal research cannot, even in principle, be used to improve human health. It is often accompanied by catchy slogan such as “If society funds mouse models ofcancer, we will find more cures for cancer in mice.” It is argued that the physiology of animals and humans are too different to allow results from animal research to be extrapolated（推断）to humans.

Such a blanket statement is falsified by numerous cases where experimentation on animals has demonstrably contributed to medical breakthroughs. The experiments on cardiovascular and pulmonary function in animals that began with Harvey andcontinued with the Oxford physiologists established the understanding of what the heartand lungs doand how they do it, on which the modern practice of internal medicine rests. Modern medical practice is inconceivable in the absence of the insights gained from these experiments. Anticoagulants were first isolated in dogs: insulin was discovered in dogs and purified in rabbits; lung surfactants were first extracted and studied in dogs; rabbits were used in the development of in vitro fertilization; mice in the development of efficient breast cancer drugs and so on.

For the sake of completeness, it must be noted that the other extreme—the notion that all medical advances are a result of animal research—is false as well. Important medical advances, such as sanitation and the discovery of aspirin, were conducted without the use of animals.