2015年職稱(chēng)英語(yǔ)考試衛(wèi)生類(lèi)B級(jí)閱讀文章(1)

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     2015年職稱(chēng)英語(yǔ)考試衛(wèi)生類(lèi)B級(jí)閱讀文章(1)

　　A Biological Clock

　　Every living thing has what scientists call a biological clock that controls behavior. The biological clock tells plants when to form flowers and when the flowers should open. It tells insects when to leave the protective cocoons and fly away，and it tells animals and human beings when to eat, sleep and wake.

　　Events outside the plant and animal affect the actions of some biological clocks. Scientists recently found, for example, that a tiny animal changes the color of its fur because of the number of hours of daylight. In the short days of winter, its fur becomes white. The fur becomes gray brown in color in the longer hours of daylight in summer.

　　Inner signals control other biological clocks. German scientists found that some kind of internal clock seems to order birds to begin their long migration flight twice each year. Birds prevented from flying become restless when it is time for the trip，but they become calm again when the time of the flight has ended.

　　Scientists say they are beginning to learn which parts of the brain contain biological clocks. An American researcher, Martin Moorhead, said a small group of cells near the front of the brain seems to control the timing of some of our actions. These cells tell a person when to awaken ，when to sleep and when to seek food . Scientists say there probably are other biological clock cells that control other body activities.

　　Dr. Moorhead is studying how our biological clocks affect the way we do our work. For example, most of us have great difficulty if we must often change to different work hours.

　　It can take many days for a human body to accept the major change in work hours. Dr. Moorhead said industrial officials should have a better understanding of biological clocks and how they affect workers. He said such understanding could cut sickness and accidents at work and would help increase a factory’s production.

　　Better Control of TB Seen If a Faster Cure Is Found

　　The World Health Organization1 estimates that about one-third of all people are infected with bacteria that cause tuberculosis. Most times, the infection remains inactive. But each year about eight million people develop active cases of TB, usually in their lungs. Two million people die of of it. The disease has increased with the spread of AIDS and drug-resistant forms of tuberculosis.

　　Current treatments take at least six months. People have to take a combination of several antibiotic drugs daily. But many people stop as soon as they feel better. Doing that can lead to an infection that resists treatment. Public health experts agree that a faster-acting cure for tuberculosis would be more effective. Now a study estimates just how effective it might be. A professor of international health at Harvard University2 led the study. Joshua Salomon says a shorter treatment program would likely mean not just more patients cured. It would also mean fewer infectious patients who can pass on their infection to others.

　　The researchers developed a mathematical model to examine the effects of a two-month treatment plan. They tested the model with current TB conditions in Southeast Asia. The scientists found that a two-month treatment could prevent about twenty percent of new cases. And it might prevent about twenty-five percent of TB deaths. The model shows that these reductions would take place between two thousand twelve and two thousand thirty. That is, if a faster cure is developed and in wide use by two thousand twelve.

　　The World Health Organization reductions the DOTS3 program in nineteen ninety. DOTS is Directly Observed Treatment, Short-course. Health workers watch tuberculosis patients take their daily pills to make sure they continue treatment.

　　Earlier this year, an international partnership of organizations announced a plan to expand the DOTS program. The ten-year plan also aims to finance research into new TB drugs. The four most common drugs used now are more than forty years old. The Global Alliance for TB Drug Development4 says its long-term goal is a treatment that could work in as few as ten doses.