题目内容
Birds that are literally half-asleep-with one brain hemisphere alert and the other sleeping-control which side of the brain remains awake, ac cording to a new study of sleeping ducks.
Earlier studies have documented half-brain sleep in a wide range of birds. The brain hemispheres take turns sinking into the sleep stage characterized by slow brain waves. The eye controlled by the sleeping hemi sphere keeps shut, while the wakeful hemisphere's eye stays open and alert. Birds also can sleep with both hemispheres resting at once.
Decades of studies of bird flocks led researchers to predict extra alertness in the more vulnerable, cud-of-the-row sleepers. Sure enough, the end birds tended to watch carefully on the side away from their companions. Ducks in the inner spots showed no preference for gaze direction.
Also, birds dozing at the end of the line resorted to single-hemi sphere sleep, rather than total relaxation, more often than inner ducks did. Rotating 16 birds through the positions in a four-duck row, the re searchers found outer birds half-asleep during some 32 percent of dozing time versus about 12 percent for birds in internal spots.
"We believe this is the first evidence for an animal behaviorally
controlling sleep and wakefulness simultaneously in different regions of the brain, "the researchers say.
The results provide the best evidence for a long-standing supposition that single-hemisphere sleep evolved as creatures scanned for enemies. The preference for opening an eye on the lookout side could be wide spread, he predicts. He's seen it in a pair of birds dozing side-by-side in the zoo and in a single pet bird sleeping by a mirror. The mirror-side eye closed as if the reflection were a companion and the other eye stayed open.
Useful as half-sleeping might be, it's only been found in birds and such water mammals as dolphins, whales, and seals. Perhaps keeping one side of the brain awake allows a sleeping animal to surface occasion ally to avoid drowning.
Studies of birds may offer unique insights into sleep. Jerome M. Siegel of the UCLA says he wonders if birds' half-brain sleep "is just the tip of the iceberg." He speculates that more examples may turn up when we take a closer look at other species.
A new study on birds' sleep has revealed that______.
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In the 1950s, the pioneers of artificial intelligence (AI) predicted that, by the end of this century, computers would be conversing with us at work and robots would be performing our housework. But as useful as computers are, they're nowhere close to achieving anything remotely resembling these early aspirations for humanlike behavior. Never mind something as complex as conversation: the most powerful computers struggle to reliably recognize the shape of an object, the most elementary of tasks for a ten-month-old kid.
A growing group of AI researchers think they know where the field went wrong. The problem, the scientists say, is that AI has been trying to separate the highest, most abstract levels of thought, like language and mathematics, and to duplicate them with logical, step-by-step programs. A new movement in Al, on the other hand, takes a closer look at the more roundabout way in which nature came up with intelligence. Many of these researchers study evolution and natural adaptation instead of formal logic and conventional computer programs. Rather than digital computers and transistors, some want to work with brain cells and proteins. The re- suits of these early efforts are as promising as they are peculiar, and the new nature-based AI movement is slowly but surely moving to the fore- front of the field.
Imitating the brain's neural network is a huge step in the right direction, says computer scientist and biophysicist Michael Conrad, but it still misses an important aspect of natural intelligence. "People tend to treat the brain as if it were made up of color-coded transistors", he explains,
"but it's not simply a clever network of switches. There are lots of important things going on inside the brain cells themselves." Specifically, Conrad believes that many of the brain's capabilities stem from the pat- tern-recognition proficiency of the individual molecules that make up each brain cell. The best way to build and artificially intelligent device, he claims, would be to build it around the same sort of molecular skills.
Right now, the notion that conventional computers and software are fundamentally incapable of matching the processes that take place in the brain remains controversial. But if it pr. yes true, then the efforts of Conrad and his fellow Al rebels could turn out to be the only game in town.
The author says that the powerful computers of today ______.
SECTION C NEWS BROADCAST
Directions: In this section you will hear everything ONCE ONLY. Listen carefully and then answer the questions that follow. At the end of each news item, you will be given 10 seconds to answer the questions.
听力原文： Investigators yesterday were trying to determine the source of a lethal gas in Malaysia that killed five Chinese cargo ship crewmen and injured one on Tuesday. The six men inhaled poisonous gas while cleaning a cargo ship during a Malaysian stopover. The ship was bound for Thailand with load of ore.
The deceased, who ranged in age from 23 to 42, were from East China's Shanghai and Jiangsu provinces.
The survivor, 23-year-old Lin Dexiang, is being treated in a local hospital near the accident site, the Kuantan port of Pahang state, about 300 kilometers east of the Malaysian capital of Kuala Lumpur.
Two officials from the Chinese Embassy have been watching the investigation and visited the scene. The source of the poison remained unclear yesterday.
According to the news, the five Chinese crewmen lost their lives
Long before "crossover" and "eclectic" became part of the journalistic vernacular, Dinah Washington defied categorization and embraced any and every type of song. Her delivery was instantly identifiable, and she prided herself on crystal-clear diction, precise pitch and spontaneity. Washington made brilliant recordings, beginning with her days as a pianist accompanying gospel pioneer Sallie Martin, through swing and R&B sessions with Count Basie and Lionel Hampton, on to modern jazz ventures with Clifford Brown, Max Roach and Cannonball Adderley and later pop hits with Brook Benton.
Author Nadine Cohodas, whose previous book on Chess Records marvelously outlined that historic company, now gives the same exacting treatment to Washington in Queen: The Life and Music of Dinah Washington. Cohodas also selected the songs on a companion CD, released on Verve Records.
Queen is the first truly comprehensive volume on the late singer. Cohodas conducted numerous interviews with insiders and family members and discovered documents and letters that reaffirm her assessments. Cohodas ably illuminates the quirks and contradictions of Washington's personality. Washington could be extremely kind and appallingly crude. She complained about her inability to find happiness in relationships, yet married seven times. A smart, extremely knowledgeable artist who had definite ideas about her music, Washington frequently clashed with bandmates, despite often being accompanied by the greatest jazz musicians on earth. Thankfully, Cohodas also presents Washington's upbeat, joyous and celebratory side, thus not totally resigning her to tragic victim status.
Sadly, Washington's ongoing conflicts and struggles with lovers, relatives and executives in many ways prevented her from achieving the fame she deserved, along with the fact that black female singers had extremely limited options during the ' 50s and early' 60s. But Washington influenced numerous vocalists who followed her, most notably Esther Phillips and Nancy Wilson, while creating an exceptional body of work that's still captivating almost 41 years after her death at 39. Songs like "Unforgettable", "This Bitter Earth," "What a Difference a Day Makes" and "Baby You Got What It Takes" remain as documents of her excellence. Queen is a wonderful and invaluable addition to music biography and cultural history.
The passage seems to indicate that Dinah Washington was NOT an ______ artist.
SECTION B INTERVIEW
Directions: In this section you will hear everything ONCE ONLY. Listen carefully and then answer the questions that follow. Questions 1 to 5 are based on an interview. At the end of the interview you will be given 10 seconds to answer each of the following five questions.
Now listen to the interview.
听力原文：Officer: Good morning. Can I help you？
Student: Yes. I'd like to know something about the British medical scheme.
Officer: Yes. What's your question？
Student: Can I use British doctors if I fall ill？
Officer: That will depend on how long your course of study is. If it is six months or more, then you are entitled to treatment from the British Medical Scheme called the National Health Service NITS, as if you were a British citizen. With the NITS, consultations with doctors are free, but you will be asked to pay something towards the cost of medicines. In 1987, this is two pounds forty for each item of medicine. You are also entitled to free treatment in British hospitals. Always make sure the doctor knows you want treatment from the NILS, as doctors also take private patients, who pay the full cost of all their treatment.
Student: How do I make sure I can be treated by the NHS？
Officer: If you are eligible for treatment, that is, you are registered on a course of six months or longer, then the first thing you should do is to register with a doctor. You should register with any doctor close to where you live--local post offices have lists. All you need to do is to visit the doctor or the doctor's receptionist during consulting hours and ask to be included on the doctor's list of patients. If the doctor decides to accept you, you will then be sent a medical card by post which will carry your National Health Service number. Take great care not to lose this. If the doctor cannot accept you, try elsewhere or contact the local Family Practitioner Committee. You can get the address from the post office or any doctor. Find out your doctor's consulting hours from the doctor or the receptionist and ask whether or not you need to make an appointment before seeing the doctor. Remember to be on time for any appointment you make. You can see him or her during these hours, unless you are seriously ill. If you are seriously ill the doctor will be called out to see you. Once you have registered you should tell your warden, landlord, landlady or a friend the name, address and telephone number of your doctor, so that if you are suddenly taken ill, the doctor can be called out to see you.
Student: I see. Could you tell me something about British hospitals？
Officer: Yes. Hospitals provide specialist treatments, or treatment for which any kind of extended stay is - required. Your doctor will recommend you to go if it is necessary. Casualty or emergency treatment following accidents is free for everyone. As not all hospitals provide such services, you should find out which local hospitals do in case you ever need treatment.
Student: How about dental care in Britain？
Officer: You can find lists of dentists who give National Health Service treatment at local main post offices. You do not register with a dentist, but you should ask whether they are willing to give you NHS treatment, as dentists are free to accept or refuse patients and to provide private treatment only. If you are accepted, you should give the dentist the NHS number which is on your medical card. There is a charge for all dental treatment. For basic treatment this could be up to seventeen pounds. More extensive dental treatment will cost more if you are not registered with a doctor. You will have to pay the full cost of dental treatment as a private patient. You will have to make an appointment to see your dentist and should give notice ff you are unable to attend an appointment, or you will be charged for loss of time. You should try to have your teeth checked at least once per year by t
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