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Solar Power Without Solar CellsA dramatic and surprising magnetic effect of light discovered by University of Michigan researchers could lead to solar power without traditional semiconductor-based solar cells."The researchers found a way to make an optical 1 "said Stephen Rand, a professor in the departments of Electrical Engineering and Computer Science, Physics and Applied Physics.Light has electric and magnetic components. Until now, scientists thought the 2 of the magnetic field were so weak that they could be ignored. What Rand and his colleagues found is that at the right intensity, when light is traveling through a material that does not conduct electricity, the light field can generate magnetic effects that are 100 million times stronger than 3 expected. 4 these circumstances, the magnetic effects develop strength equivalent to a strong electric effect."This could lead to a new kind of solar cell without semiconductors and without absorption to produce charge separation," Rand said. "In solar cells, the 5 goes into a material, gets absorbed and creates heat. Here, we expect to have a very low heat load. Instead of the light being absorbed, energy is stored in the magnetic moment. Intense magnetization can be induced by intense light and then it is ultimately capable of providing a capacitive power 6 ." What makes this possible is a previously undetected brand of "optical rectification," says William Fisher, a doctoral student in applied physics. In traditional optical rectification, light"s electric field causes a charge separation, or a pulling 7 of the positive and negative charges in a material. This sets up a voltage, similar to 8 in a battery.Rand and Fisher found that under the right circumstances and in right types of materials, the light"s magnetic field can also create optical rectification. The light must be shone through a 9 that does not 10 electricity, such as glass. And it must be focused to an intensity of 10 million watts per square centimeter. Sunlight isn"t this intense on its own, but new materials are being sought that would work at lower intensities, Fisher said."In our most recent paper, we show that incoherent light like sunlight is theoretically almost as 11 in producing charge separation as laser light is," Fisher said."This new 12 could make solar power cheaper, "the researchers say. They predict that with improved materials they could achieve 10 percent efficiency in 13 solar power to useable energy. That"s equivalent to today"s commercial-grade solar cells."To manufacture 14 solar cells, you have to do extensive semiconductor processing," Fisher said. "All we would need are lenses to focus the light and a fiber to guide it. Glass works for 15 . It"s already made in bulk, and it doesn"t require as much processing. Transparent ceramics might be even better."
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The Northern LightsThe sun is stormy and has its own kind of weather. It is so hot and active that even the Sun"s gravity cannot hold its atmosphere in check! Energy flows away from the Sun toward the Earth in a stream of electrified particles that move at speeds around a million miles per hour. These particles are called plasma, and the stream of plasma coming from the Sun is called the solar wind. The more active the Sun, the stronger the solar wind.The solar wind constantly streams toward the Earth, but don"t worry because a protective magnetic field surrounds our planet. The same magnetic field that makes your compass point north also steers the particles from the Sun to the north and south poles. The charged particles become trapped in magnetic belts around the Earth. When a large blast of solar wind crashes into the Earth"s magnetic field, the magnetic field first gets squeezed and then the magnetic field lines break and reconnect.The breaking and reconnecting of the magnetic field lines can cause atomic particles called electrons trapped in the belts to fall into the Earth"s atmosphere at the poles. As the electrons fall into the Earth, they collide with gas molecules in the atmosphere, creating flashes of light in the sky. Each atmospheric gas glows a different color. Oxygen and nitrogen glows red and green and nitrogen glows violet-purple. As these various colors glow and dance in the night sky, they create the Northern Lights and the Southern Lights.Watching auroras is fun and exciting, but normally you can only see them in places far north like Alaska and Canada. The movement of the aurora across the sky is usually slow enough to easily follow with your eyes but they can also pulsate, flicker, or even move like waves. During solar maximum, auroras are seen as far south as Florida, even Mexico!Auroras often seem to be very close to the ground, but the lowest aurora is still about 100 kilometers above the ground, a distance much higher than clouds are formed or airplanes can fly. A typical aurora band can be thousands of kilometers long, a few hundred kilometers high, but only a few hundred meters thick.We hope you are able to travel to far-north places like the Arctic Circle and see the Northern Lights at least once during your lifetime. We know you will never forget it! An aurora is generally close to the ground and is very long and thick.
Milosevic"s DeathFormer Yugoslav leader Slobodan Milosevic was found dead last Saturday in his cell at the Hague-based International Criminal Tribunal for the former Yugoslavia. The 64-year-old had been on trial there since February 2002.Born in provincial Pozarevac in 1941, he was the second son of a priest and a school teacher. Both of his parents died when he was still a young adult. The young Milosevic was "untypical", says Slavolub Djukic, his unofficial biographer. He was "not interested in sports, avoided excursions (短途旅行) and used to come to school dressed in the old-fashioned way—white shirt and tie." One of his old friends said, he could "imagine him as a station-master or punctilious (一丝不苟) civil servant."Indeed that is exactly what he might have become, had he not married Mira. She was widely believed to be his driving force.At university and beyond he did well. He worked for various firms and was a communist party member. By 1986 he was head of Serbia"s Central Committee. But still he had not yet really been noticed.It was Kosovo that gave him his chance. An autonomous province of Serbia, Kosovo was home to an Albanian majority and a Serbian minority. In 1989, he was sent there to calm fears of Serbians who felt they were discriminated against. But instead he played the nationalist card and became their champion. In so doing, he changed into a ruthless (无情的) and determined man. At home with Mira he plotted the downfall of his political enemies. Conspiring (密谋) with the director of Serbian T. V., he mounted a modern media campaign which aimed to get him the most power in the country.He was elected Serbian president in 1990. In 1997, he became president of Yugoslavia. The rest of the story is well-known: his nationalist card caused Yugoslavia"s other ethnic groups to fight for their own rights, power and lands. Yugoslavia broke up when four of the six republics declared independence in 1991. War started and lasted for years and millions died. Then Western countries intervened. N.A.T.O. bombed Yugoslavia, and he eventually stepped down as state leader in 2000.Soon after this, Serbia"s new government, led by Zoran Djindjic, arrested him and sent him to face justice at the Yugoslav war crimes tribunal in the Hague. What happened in 1991
Smoke Gets in Your Mind1. Lung cancer, hypertension, heart disease, birth defects—we are all too familiar with the dangers of smoking. But add to that list a frightening new concern. Mental illness. According to some controversial new findings, if smoking does not kill you, it may, quite literally, drive you to despair.2. The tobacco industry openly pushes its product as something to lift your mood and soothe anxiety. But the short-term feel-good effect may mask the truth: that smoking may worsen or even trigger anxiety disorders, panic attacks and depression, perhaps even schizophrenia.3. Cigarettes and mental illness have always tended to go together. An estimated 1.25 billion people smoke worldwide. Yet people who are depressed or anxious are twice as likely to smoke, and up to 88 per cent of those with psychotic disorders such as schizophrenia smokers. A recent American survey concluded that around half of all cigarettes burn in the fingers of those with mental illness.4. But the big question is why The usual story is that the illness comes first. Mentally ill people take up smoking, or smoke more to alleviate some of their distress. Even when smoking seems to start before the illness, most doctors believe that early but invisible symptoms of the disorder spark the desire to light up. But perhaps something more sinister is going on.5. A growing number of researchers claim that smoking is the cause, not the consequence of clinical depression and several forms of anxiety. "We know a lot about the effects of smoking on physical health, and now we are also starting to see the adverse effects in new research on mental illness," says Naomi Breslau, director of research at the Henry Ford Health Care System in Detroit.6. Breslau was one of the first to consider this heretical possibility. The hint came from studies, published in 1998, which followed a group of just over 1,000 young adults for a five-year period. The 13 percent who began the study with major depression were around three times more likely to progress from being light smokers to daily smokers during the course of the study, though there was no evidence that depression increased the tendency to take up smoking. But a history of daily smoking before the study commenced roughly doubled the risk of developing major depression during the five-year period. Smoking, it seems, could predate illness.7. At first Breslau concluded that whatever prompts people to smoke might also make them depressed. But as the results of other much larger studies began to back the statistical link, she became more convinced than ever that what she was seeing were signs that smoking, perhaps the nicotine itself, could somehow affect the brain and cause depression.8. One of these larger studies was led by Goodman, a pediatrician. She followed the health of two groups of teenagers for a year. The first group of 8,704 adolescents were not depressed, and might or might not have been smokers, while the second group of 6,947 were highly depressed and had not been smokers in the past month. After a year her team found that although depressed teenagers were more likely to have become heavy smokers, previous experimentation with smoking was the strongest predictor of such behavior, not the depression itself. What is more important is that teenagers who started out mentally fit but smoked at least one packet per week during the study were four times more likely to develop depression than their non-smoking peers. Goodman says that depression does not seem to start before cigarette use among teens. "Current cigarette use is however, a powerful determinant of developing high depressive symptoms."9. Breslau, too, finds that smokers are as much as four times more likely to have an isolated panic attack and three times more likely to develop longer-term panic disorder than non-smokers. It"s a hard message to get across, because many smokers say they become anxious when they quit, not when they smoke. But Breslau says that this is a short-lived effect of withdrawal which masks the reality that, in general, smokers have higher anxiety levels than non-smokers or ex-smokers. Paragragh 8 ______
针灸治疗气血不足型痛经应取以下哪组腧穴
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