【正文】 完型When travelers pass from one time zone to another, they suffer from disrupted circadian rhythms, an unfortable feeling known as jet lag. For instance, if you travel from California to New York, you lose 3 hours according to your body39。s clock. You will feel tired when the alarm rings at 8 . the next morning because, according to your body39。s clock, it is still 5 . It usually takes several days for your body39。s cycles to adjust to the new time. To reduce the effects of jet lag, some doctors try to manipulate the biological clock with a technique called light therapy. They expose people to special lights, many times brighter than ordinary household light, for several hours near the time the subjects want to wake up. This helps them reset their biological clocks and adjust to a new time zone.Symptoms much like jet lag are mon in people who work nights or who perform shift work. Because these people39。s work schedules are at odds with powerful sleepregulating cues like sunlight, they often bee uncontrollably drowsy during work, and they may suffer insomnia or other problems when they try to sleep. Shift workers have an increased risk of heart problems, digestive disturbances, and emotional and mental problems, all of which may be related to their sleeping problems. The number and severity of workplace accidents also tend to increase during the night shift. Major industrial accidents attributed partly to errors made by fatigued nightshift workers include the Exxon Valdez oil spill and the Three Mile Island and Chernobyl nuclear power plant accidents. One study also found that medical interns working on the night shift are twice as likely as others to misinterpret hospital test records, which could endanger their patients. It may be possible to reduce shiftrelated fatigue by using bright lights in the workplace, minimizing shift changes, and taking scheduled naps.Many people with total blindness experience lifelong sleeping problems because their retinas are unable to detect light. These people have a kind of permanent jet lag and periodic insomnia because their circadian rhythms follow their innate cycle rather than a 24hour one. Daily supplements of melatonin may improve nighttime sleep for such patients. However, since the high doses of melatonin found in most supplements can buildup in the body, longterm use of this substance may create new problems. Because the potential side effects of melatonin supplements are still largely unknown, most experts discourage melatonin use by the general public.閱讀AA small card sits above an empty shelf in the Whole Foods store in Petaluma, California. “Consumers are advised not to eat fresh bagged spinach at this time. As a precaution, Whole Foods Market has temporarily removed all fresh spinach and fresh salad mixes containing spinach from its stores.”O(jiān)n September 14th the Centers for Disease Control and Prevention in Atlanta issued the first of several daily alerts concerning an outbreak of 0157:H7, a potentially lethal pathogen typically associated with adulterated beef. Investigators had traced it to consumption of fresh raw spinach sold in bags. A few days later, an investigation conducted by the Food and Drug Administration (FDA) had narrowed down the culprits to a Californiabased grower, Natural Selection Foods, and at least one of its distributors. So far, a 77yearold woman in Wisconsin has died from eating spinach traced back to Natural Selection, and 146 people in 23 states are ill, some very seriously. Half of the victims have been hospitalized, a high rate that may indicate an especially virulent strain of E. coli.Investigators continue to search for the cause of the outbreak. They have scoured the pany’s processing plant as well as the farms that grow the spinach, looking at everything from irrigation water to the proximity of livestock, with no sure connections made so far. The fact that Natural Selection is in California’s Salinas Valley has raised alarms, however. According to the FDA, fresh produce from the valley, including spinach, has been the source of nine E. coli outbreaks since1995. Moreover Natural Selection, which supplies several supermarket chains across the United States with conventionally produced fresh spinach, is also the nation’s largest grower and shipper of certified organic produce, under its Earthbound Farm brand. If organic spinach bees implicated, the financial consequences for the organic sector of the fresh produce market, which prides itself on its purity, could be severe. But with the FDA advising consumers not to eat fresh spinach from any source until further notice, the outbreak could ruin California’s whole spinach industry. The state grows about threequarters of the American crop. In recent years the market for fresh spinach has benefited hugely from what one producers’ spokesman calls “a great health profile”. In2005, per capita consumption in America was forecast at pounds (one kilogram), up from just pounds ten years ago. That total isn’t likely to increase again for a while.閱讀BAnother round has just been fought in the battle between tobacco panies and those who regard them as spawn of the devil. In appear just published in the Lancet, with the provocative title “Secret science: tobacco industry research on smoking behavior and cigarette toxicity”, David Hammond, of Waterloo University in Canada and Neil Collishaw and Cynthia Collard, two members of Physicians for a SmokeFree Canada, a lobby group, criticize the behavior of Br