【正文】 itioning needs. They don’t emphasize mass transit and reduce automobile, use. In fact, many local governments are taking a handsoff approach.” Thus, she urges them to change their idle policies and to take strong steps to prevent the harmful effects of’ climate change on cities. Free Statins With Fast Food Could Neutralize Heart Risk Fast food outlets could provide statin drugs free of charge so that customers can reduce the heart disease dangers of fatty food, researchers at Imperial College London suggest in a new study. Statins reduce the amount of unhealthy “ LDL” cholesterol in the blood. A wealth of trial data4 has proven them to be highly effective at lowering a person’ s heart attack risk In a paper published in the American Journal of Cardiology, Dr Darrel Francis and colleagues calculate that the reduction in heart attack risk offered by a statin is enough to offset the increase in heart attack risk from eating a cheeseburger and drinking a milkshake. Dr Francis, from the National Heart and Lung Institute at Imperial College London, who is the senior author of the study, said: “ Statins don’ t cut out all of the unhealthy effects of cheeseburgers and French fries. It’ s better to avoid fatty food altogether. But we’ve worked out that in terms of your possibility of having a heart attack, taking a statin can reduce your risk to more or less the same degree as a fast food meal increases it. ” It’s ironic that people are free to take as many unhealthy condiments in fast food outlets as they like, but statins, which are beneficial to heart health, have to be prescribed. It makes sense to make riskreducing statins available just as easily as the unhealthy condiments that are provided free of charge. It would cost less than 5 pence per customer —— not much different to a sachet of sugar, “ Dr Francis said. When people engage in risky behaviours like driving or smoking, they’ re encouraged to take measures that lower their risk, like wearing a seatbelt or choosing cigarettes with filters. Taking a stain is a rational way of lowering some of the risks of eating a fatty meal. Better Solar Energy Systems: More Heat, More Light Solar photovoltaic thermal energy systems, or PVTs, generate both heat and electricity, but until now they haven’t been very good at the heatgenerating part pared to a standalone solar thermal collector. That’s because they operate at low temperatures to cool crystalline silicon solar cells, which lets the silicon generate more electricity but isn’t a very efficient way to gather heat. That’ s a problem of economics. Good solar hotwater systems can harvest much more energy than a solarelectric system at a substantially lower cost. And it， s also a space problem： photovoltaic cells can take up all the space on the roof, leaving little room for thermal applications. In a pair of studies, Joshua Pearce, an associate professor of materials science and engineering, has devised a solution in the form of a better PVT made with a different kind of silicon. His research collaborators are Kunal Girotra from ThinSilicon in California and Michael Pathak and Stephen Harrison from Queen’s University, Canada. Most solar panels are made with crystalline silicon， but you can also make solar cells out of amorphous silicon,monly known as thinfilm silicon. They don’ t create as much electricity, but they are lighter, flexible, and cheaper. And, because they require much less silicon, they have a greener footprint. Unfortunately， thinfilm silicon solar cells are vulnerable to some badnews physics in the form of the StaeblerWronski effect. 342 mess microscopic M “ That means that their efficiency drops when you expose them to light — pretty much the worst possible effect for a solar cell,” Pearce explains，which is one of the reasons thin film solar panels make up only a small fraction of the market. However, Pearce and his team found a way to engineer around the StaeblerWronski effect by incorporating thinfilm silicon in a new tpye of PVT. You don’ t have to cool down thinfilm silicon to make it work. In fact， Pearce’ s group discovered that by heating it to solarthermal operating temperatures， near the boiling point of water, they could make thicker cells that largely overcame the StaeblerWronski effect. When they applied the thinfilm silicon directly to a solar thermal energy collector, they also found that by baking the cell once a day， they boosted the solar cell’ s electrical efficiency by over 10 percent. Sharks Perform a Service for Earth’s Watersy It is hard to get people to think of sharks as anything but a deadly enemy. They are thought to attack people frequently. But these fish perform a valuable service for earth’s waters and for human beings. Yet business and sport fishing3 are threatening their existence. Some sharks are at risk of disappearing from earth. Warm weather may influence both fish and shark activity. Many fish swim near coastal areas because of their warm waters. Experts say sharks may follow the fish into the same areas,where people also swim. In fact, most sharks do not purposely charge at or bite humans. They are thought to mistake a person for a sea animal, such as a seal or sea lion. That is why people should not swim in the ocean when the sun goes down or es up. Those are the times when sharks are looking for food. Experts also say that bright colors and shiny jewelry may cause sharks to attack. A shark has an extremely good sense of smell4. It can find small amounts of substances in water, such as blood, body liquids and chemicals produced by animals. These powerful senses help sharks find their food. Sharks eat fish, an