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Children attending schools located in high-traffic zones have a 45 percent increased risk of developing asthma, even though time spent at school only accounts for about one-third of a child’s waking hours, according to new research. Asthma is the most common chronic childhood illness in developed countries and has been linked to environmental factors such as traffic-related air pollution. "While residential traffic-related pollution has been associated with asthma, there has been little study of the effects of traffic exposure at school on new onset asthma," says Rob McConnell, professor of preventive medicine at USC’s Keck School of Medicine. "Exposure to pollution at locations other than home, especially where children spend a large portion of their day and may engage in physical activity, appears to influence asthma risk as well." The study appears online in the journal Environmental Health Perspectives. The study drew upon data from the Children’s Health Study (CHS), a longitudinal study of children in Southern California communities that was designed to investigate the chronic effects of air pollution on respiratory health. Using a cohort of 2 497 kindergarten and first grade children who were asthma-free when they entered the study, researchers examined the relationship of local traffic around schools and homes to diagnosis new onset asthma that occurred during three years of follow-up. Traffic-related pollution exposure was assessed based on a model that took into account traffic volume, distance to major roadways from home and school and local weather conditions. Regional ambient ozone, nitrogen dioxide (二氧化氮) and particulate matter were measured continuously at one central site in each of the 13 study communities. The design allowed investigators to examine the joint effects of local traffic-related pollution exposure at school and at home and of regional pollution exposure affecting the entire community. Researchers found 120 cases of new asthma. The risk associated with traffic-related pollution exposure at schools was almost as high as for residential exposure, and combined exposure accounting for time spent at home and at school had a slightly larger effect. Although children spend less time at school than at home, physical education, and other activities that take place at school may increase ventilation rates and the dose of pollutants getting into the lungs, McConnell notes. Traffic-related pollutant levels may also be higher during the morning hours when children are arriving at school. Despite a state law that prohibits school districts from building campuses within 500 feet of a freeway, many Southern California schools are located near high-traffic areas, including busy surface streets. "It’s important to understand how these micro-environments where children spent a lot of their time outside of the home are impacting their health," McConnell says. "Policies that reduce exposure to high-traffic environments may help to prevent this disease. " The study was funded by grants from the National Institute of Environmental Health Sciences, the US Environmental Protection Agency, the South Coast Air Quality Management District, and the Hastings Foundation. Which of the following is TRUE according to the text
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Feeling anxious Your mood may actually change how your dinner tastes, making the bitter and salty flavors recede, according to new research. This link between the chemical balance in your brain and your sense of taste could one day help doctors to treat depression. There are currently no on-the-spot tests for deciding which medication will work best in individual patients with this condition. Researchers hope that a test based on flavor detection could help doctors to get more prescriptions right first time. It has long been known that people who are depressed have lower-than-usual levels of the brain chemicals serotonin or noradrenaline, or in some cases both. Many also have a blunted sense of taste, which is presumably caused by changes in brain chemistry. To unpick the relationship between the two, Lucy Donaldson and her colleagues at the University of Bristol, UK, gave 20 healthy volunteers two antidepressant drugs, and checked their sensitivity to different tastes. The drug that raised serotonin levels made people more sensitive to sweet and bitter tastes, the team reports in the Journal of Neuroscience. The other, which increased noradrenaline, enhanced recognition of bitter and sour tastes. In healthy people, volunteers whose anxiety levels were naturally higher were less sensitive to bitter and salty tastes. "What hasn’t been done beore is to look precisely at which tastes are affected in depression," says Donaldson. Now the results are in, "we can discriminate between the chemicals and the tastes that seem to be altered," she says. Testing sensitivity to sweet and sour tastes could potentially help doctors to pick up on which chemicals are dipping, guiding them when choosing which drug to rectify the problem. Currently, doctors rely on physical and emotional symptoms to make a best guess at an individual’s imbalance, prescribe a drug and wait about a month to check on any improvement. Good doctors have about a 60-80% success rate in selecting the right drug the first time, says psychiatrist Jan Melichar, a co-author on the paper. Are there any decent tests for prescribing drugs for depression "No. We do a best guesstimate," says Melichar. "I’m excited by this finding because in 3, 5 or 7 years we could have a simple taste test. " Next, the team plans to perform similar tests in depressed people, and in healthy volunteers given another brain chemical called tryptophan. This chemical would lower the healthy subjects’ levels of serotonin, as actually happens in depressed patients. The work has also generated interest from flavor houses--companies that develop chemicals for the food and drink industry--who are interested in making foods taste just as sweet with half the amount of sugar. "Theoretically there would be the possibility of enhancing your meal with drugs that affect brain chemicals so that things would taste better--you couid have a ’designer taste tablet’," Donaldson says. The word "blunted" (Line 2, Paragraph 2) most probably means ______.
It has been almost half a decade since Norman Mailer described leas Vegas in his novel The American Dream. But it (1) to be one of the most (2) and exhilarating (使人愉快的) holiday destinations in the world. An end-less (3) of colorful sights and activities are surrounded by skyscrapers and the magnificent Nevada desert. With (4) shopping, luxury spas, five-star dining and some of the most extravagant entertainment, you will (5) see, this is a city (6) offers an experience like no other. Perhaps the enduring appeal of this " (7) capital of the world", though, is that it always has something (8) to offer. Recently the Hard Rock Café has been (9) up its act, completing with a new 42 000 sq ft venue, 1 000-seater cinema and an "interactive rock wall"-allowing customers the chance to (10) images of Hard Rock’s collection. City Center is an $ 8.5 billion (￡5.3 billion) complex on the Strip; a place that, in a city already (11) with extraordinary casinos (娱乐场) and hotels, stands out from the (12) It was the largest privately (13) construction project in the US and has three stand-alone hotels, a sprawling shopping and entertainment district and two 37-storey glass towers of (14) flats, designed by the likes of Norman Foster. Another Las Vegas (15) , Planet Hollywood, has (16) with luxury developers to create Westgate Towers--where you could own a piece of the action and a chance to come back to Las Vegas every year. (17) , the only thing you’ll (18) of in Vegas is not knowing which club, restaurant or spa to choose from. But then you can always ask a(n) (19) or the concierge--the fantastic thing about this city is that its residents (20) it as much as you will.
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