Electrical devices (仪器) could soon use power made by human energy. Scientists say they have developed an experimental device that produces electricity from the physical movement of a person walking. British scientist Max Donelan and other scientists in Canada and the United States developed the device.

    The device connects to a person's knee. As the person walks, the device captures energy each time the person slows down. To do this, the device helps with the slowing down movement of the leg. The movements of the walking person push parts of a small machine that produces electricity. Using the device, an adult walking quickly could produce thirteen watts of electricity in just a minute. Donelan says walking at that speed could produce enough power to operate a laptop computer for six minutes.

    There are several possible uses for the device. Developers say it could help people who work in areas without electricity to operate small computers. The device could also be used in hospitals to operate heart pacemakers (起搏器). It could even be used to assist in the movement of robotic arms and legs.

    The experimental version of the device weighs about one and a half kilograms, but it is too costly for most people to buy. But the researchers hope to make a lighter, less costly version. An improved version should be ready in one year.

    The developers hope the device will one day help developing countries. Nearly twenty-five percent of people around the world live without electric power.

    A similar product was invented in 2005 by Larry Rome of the University of Pennsylvania. He created a bag carried on a person's back that also produces power from walking. The knee device does not produce as much electricity as the bag. But the bag requires the walker to carry a load of twenty to thirty kilograms.

    Some years ago, writing in my diary used to be a usual activity. I would return from school and spend the expected half hour recording the day's event, feelings, and impressions in my little blue diary. I did not really need to express my emotions by way of words, but I gained a certain satisfaction from seeing my experiences forever recorded on paper. After all, isn't accumulating memories a way of preserving the past?

    When I was thirteen years old, I went on a long journey on foot in a great valley, well-equipped with pens, a diary, and a camera. During the trip, I was busy recording every incident, name and place I came across. I felt proud to be spending my time productively, dutifully preserving for future generations a detailed description of my travels. On my last night there, I wandered out of my tent, diary in hand. The sky was clear and lit by the glare of the moon, and the walls of the valley looked threatening behind their screen of shadows. I automatically took out my pen….

    At that point, I understood that nothing I wrote could ever match or replace the few seconds I allowed myself to experience the dramatic beauty of the valley. All I remembered of the previous few days were the dull characterizations I had set down in my diary.

    Now, I only write in my diary when I need to write down a special thought or feeling. I still love to record ideas and quotations that strike me in books, or observations that are particularly meaningful. I take pictures, but not very often—only of objects I find really beautiful. I'm no longer blindly satisfied with having something to remember when I grow old. I realize that life will simply pass me by if I stay behind the camera, busy preserving the present so as to live it in the future.

    I don't want to wake up one day and have nothing but a pile of pictures and notes. Maybe I won't have as many exact representations of people and places; maybe I'll forget certain facts, but at least the experiences will always remain inside me. I don't live to make memories—I just live, and the memories form. themselves.

    If you are taking vitamin supplements to reduce your risk of heart disease or cancer, a group of health experts want you to know that those vitamins may actually increase your risk of cancer.

    The US Preventive Services Task Force came to this conclusion after reviewing dozens of studies.

    Nearly half of adults in the US take at least one vitamin or mineral supplement on a regular basis. These pills are advertised as a way to promote general health. In some cases, manufacturers promote them as cancer fighters and heart protectors.

    Studies in animals and in laboratory dishes suggest that oxidative(氧化性的) stress contributes to diseases like cancer and heart disease. If so, there is a reason to believe that antioxidants—including beta-carotene, vitamins A, C, and E—could be useful as preventive medicines.

    But when the Task Force examined the medical evidence on vitamins, it found “inadequate(不充分的) evidence” to support the claims that vitamin and mineral supplements benefit healthy adults.

    “Cardiovascular(心血管的) disease and cancer have a significant health impact in America, and we all want to find ways to prevent these diseases,” Dr. Virginia Moyer, who heads the Task Force, said in a statement. But so far, she added, the medical evidence does not show that taking vitamins is helpful in this regard.

    However, the Task Force did find “adequate evidence” that people with a raised risk for lung cancer actually increase their risk further by taking beta-carotene, a precursor of vitamin A.

    The Task Force recommendations of taking vitamins regularly apply to healthy adults aged 50 and older who don't have “special nutritional needs”. The advice does not apply to children, women who are pregnant or may become pregnant, people with chronic illnesses, or people who have to take supplements because they can't get all their essential nutrients from their diet.

    Cooperation at work is generally seen as a good thing. The latest survey by the Financial Times of what employers want from MBA graduates found that the ability to work with a wide variety of people was what managers wanted most. But managers always have to balance the benefits of teamwork, which help ensure that everyone is working towards the same goal, with the dangers of “groupthink” when critics are reluctant to point out a plan's drawbacks for fear of being kept out of the group. The disastrous Bay of Pigs invasion of Cuba in 1961 was a classic case of groupthink. Skeptics were reluctant to challenge John F. Kennedy, the newly elected American president.

    Modern communication methods mean that cooperation is more frequent. Workers are constantly in touch with each other via e-mail messaging groups or mobile calls. But does that improve, or lower performance? A new study by three American academics, tried to answer this question. They set a logical problem (designing the shortest route for a travelling salesman visiting various cities). Three groups were involved: one where subjects acted independently; another where they saw the solutions posted by team members at every stage; and a third where they were kept informed of each other's views only intermittently.

    The survey found that members of the individualist group reached the premier solution more often than the constant cooperators but had a poorer average result. The intermittent cooperators found the right result as often as the individualists, and got a better average solution. When it comes to ideal generation, giving people a bit of space to a solution seems to be a good idea. Occasional cooperation can be a big help: most people have benefited from a colleague's brainwave or (just as often) wise advice to avoid a particular course of action.

    Further clues come from a book, Superminds, by Thomas Malone of the Massachusetts Institute of Technology. He says that three factors determine the collective intelligence of cooperating groups: social intelligence (how good people were at rating the emotional states of others); the extent to which members took part equally in conversation (the more equal, the better); and the cooperation of women in the group (the higher, the better). Groups ranked highly in these areas cooperated far better than others.

    In short, cooperation may be a useful tool but it doesn't work in every situation.

    You probably know who Marie Curie was, but you may not have heard of Rachel Carson. Of the outstanding ladies listed below, who do you think was the most important woman of the past 100 years?

    Jane Addams(1860-1935)

    Anyone who has ever been helped by a social worker has Jane Addams to thank. Addans helped the poor and worked for peace. She encouraged a sense of community(社区)by creating shelters and promoting education and services for people in need . In 1931, Addams became the first American woman to win the Nobel Peace Prize.

    Rachel Carson(1907-1964)

    If it weren't for Rachel Carson, the environmental movement might not exist today. Her popular 1962 book Silent Spring raised awareness of the dangers of pollution and the harmful effects of chemicals on humans and on the world's lakes and oceans.

    Sandra Day O'Connor(1930-present)

    When Sandra Day O'Connor finished third in her class at Stanford Law School, in 1952, she could not find work at a law firm because she was a woman. She became an Arizona state senator(参议员) and ,in 1981, the first woman to join the U.S. Supreme Court. O'Connor gave the deciding vote in many important cases during her 24 years on the top court.

    Rosa Parks(1913-2005)

    On December 1, 1955, in Montgomery, Alabama, Rasa Parks would not give up her seat on a bus to a passenger. Her simple act landed Parks in prison. But it also set off the Montgomery bus boycott. It lasted for more than a year, and kicked off the civil-rights movement. "The only tired I was, was tired of giving in," said Parks.

    As the temperature rises, sweaty humans are making a response that is further worsening the problem of climate change. At present, the world just has 1.6 billion air conditioning units, but these units use a surprising total of ten percent of all global electricity supply. While less than a third of families globally are so equipped, the most AC-addicted countries are Japan (in 91 percent of families), the US (90 percent) and South Korea(86 percent).

    New research by the International Energy Agency (IEA) guesses that the total number of AC units is likely to increase to over 5.6 billion by 2050－equal to ten new units being sold every second for more than 30 years－with sales driven particularly by India, China and Indonesia. This will make the use of air conditioning one of the world's largest demands for energy.

    "Growing electricity demand for air conditioning is one of the most critical blind spots in today's energy debate," argues Faith Birol, executive director of the IEA. "With rising incomes, air conditioner ownership will skyrocket, especially in the developing world. While this will improve daily lives, it is quite necessary that efficiency performance be prioritized."

    Birol and the IEA stress the need for new efficiency standards to ensure that consumers are at least buying units that require significantly less power to function, therefore decreasing the total energy demand. Variations on the traditional "vapor compression" technology, which has formed the basis for AC units for more than a century, may appear really important. A water-based system was recently developed by researchers at the National University of Singapore (NUS), which uses 40 percent less electricity and produces only one by-product: drinkable water.

    "Our cooling system can be tailored for all types of weather conditions, from wet climate in the tropics to dry climate in the deserts," says associate professor Ernest Chua at NUS. "While it can be used for indoor living and commercial spaces, it can also be easily used to provide air conditioning for blocks of buildings in an energy-efficient manner."