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    LONDON－Scientists have found an unusual way to prevent our planet from overheating: move it to a cooler spot. All you have to do is send a few comets (彗星) in the direction of Earth, and its orbit will be changed too. Our world will then be sent spinning into a safer, colder part of the solar system.

    This idea for improving our climate comes from a group of U. S. National Aeronautics and Space Administration (NASA) engineers and American astronomers. They say their plan could add another six billion years to the useful lifetime of our planet－effectively doubling its working life.

    The plan put forward by Dr. Laughlin, and his colleagues Don Korycansky and Fred Adams, needs carefully directing a comet or asteroid so that it passes close by our planet and sends some of its gravitational energy to Earth.

    “Earth's orbital speed would increase as a result and we would move to a higher orbit away from the Sun,” Laughlin said.

    Engineers would then direct their comet so that it passed close to Jupiter or Saturn. The comet would pick up energy from one of these giant planets. Later its orbit would bring it back to Earth, and the process would be repeated.

    In the short term, the plan provides an ideal way to global warming, although the team was actually concerned with a much greater danger. The Sun is certain to heat up in about a billion years and so “seriously compromise” our biosphere (生物圈) －by cooking us.

    That's why the group decided to try to save Earth.

    The plan has one or two worrying aspects, however. For a start, space engineers would have to be very careful about how they directed their asteroid or comet towards Earth. The smallest miscalculation (误算) in orbit could fire it straight at Earth--with deadly consequences.

    There is also the question of the Moon. As the current issue of Scientific American magazine points out, if Earth was pushed out of its current position, it is “most likely the Moon would be stripped away from Earth”. This would greatly change our planet's climate.

    Our library offers different types of studying places and provides a good studying environment.

Zones

    The library is divided into different zones. The upper floor is a quiet zone with over a thousand places for silent reading, and places where you can sit and work with your own computer. The reading places consist mostly of tables and chairs. The ground floor is the zone where you can talk. Here you can find sofas and armchairs for group work.

Computers

    You can use your own computer to connect to the wi-fi specially prepared for notebook computers; your can also use library computers, which contain the most commonly used applications, such as Microsoft Office. They are situated in the area known as the Experimental Field on the ground floor.

Group-study places

    If you want to discuss freely without disturbing others, you can book a study room or sit at a table on the ground floor. Some study rooms are for 2-3 people and others can hold up to 6-8 people. All rooms are marked on the library maps.

    There are 40 group-study rooms that must be booked via the website. To book, you need an active University account and a valid University card. You can use a room three hours per day, nine hours at most per week.

Storage of Study Material

    The library has lockers for students to store course literature. When you have obtained at least 40 credits(学分), you may rent a locker and pay 400 SEK for a year's rental period.

Rules to be Followed

    Mobile phone conversations are not permitted anywhere in the library. Keep your phone on silent as if you were in a lecture and exit the library if you need to receive calls.

    Please note that food and fruit are forbidden in the library, but you are allowed to have drinks and sweets with you.

    In many American schools the holiday celebrating Dr. Martin Luther King Jr.'s birthday is used as an opportunity to teach children about his life and legacy. But in too many of those same schools, Black children's extraordinary talents are still being wasted today. Nearly three-quarters of Black fourth and eighth grade public school students cannot read or compute at grade level. Black students made up only 18 percent of students in public schools in 2009-2010 but were 40 percent of students who received one or more out-of-school suspensions (暂被停学). A Black public school student is suspended every four seconds. Black students are more than twice as likely to drop out of school as White students. Each school day 763 Black high school students drop out.

    So I applaud the U.S. Departments of Education and Justice for their recent action to address harmful school discipline policies that push so many thousands of black children out of school each year and into the juvenile (青少年) justice and adult prison pipeline. If the education system is to do its part in replacing it with a cradle to college, career and success pipeline, we must end the current practice where children in the greatest need are suspended from school mostly for nonviolent offenses.

    These resources, officially known as "guidance," will help schools and districts meet their legal responsibility to protect students from discrimination (歧视) on the basis of race, color or national origin as required under Title VI of the Civil Rights Act of 1964. As we recognize the 50^th anniversary of the Civil Rights Act of 1964 and so many other important hard-won victories in the Civil Rights Movement this year, we must remember those victories could be lost without meaningful enforcement of the laws advocates fought so hard to win half a century ago.

    While the guidance does not prohibit (禁止) schools or districts from using any particular nondiscriminatory policy, it does call into question some policies that have historically excluded Black students and are of questionable educational value including "zero tolerance" discipline policies which require mandatory (强制的) consequences for certain infractions (违反), and policies that prevent students from returning to school after completion of a court sentence.

    Information of the new guidance recommendations is available at this government website for almost every school and district in the country. Check your own school district now to see whether the discipline policy is focused on creating a positive school climate and preventing misbehavior, whether consequences are clear, appropriate and consistent, and whether there is a commitment to fairness in the application of discipline.

    Angad Rekhi, a graduate student and an assistant professor of electrical engineering, has developed a wake-up receiver. This wake-up receiver has many potential applications, particularly in designing the next generation of net worked devices, including so called "smart" devices that can communicate directly with one another without human intervention (介入).

    Once attached to a device, a wake-up receiver listens for a unique ultrasonic（超声波）pattern that tells it when to turn the device on. It needs only a very small amount of power to maintain this constant listening, so it still saves energy overall while extending the battery life of the larger device. A well-designed wake-up receiver also allows the device to be turned on from a significant distance.

    Given the increased interest in networked devices, researchers and industry organizations are starting to define what features and techniques will become standard. Regardless of whether this ultrasound wake-up receiver is among these standard designs, it is likely wake-up receivers of some kind will be combined into commercial applications soon.

    By comparison, the ultrasound wake-up receiver requires a battery but has much greater range than the wirelessly powered devices, while still maintaining a long lifetime due to extremely low power draw. These two technologies-wireless power and wake-up receivers-would likely serve different purposes but both indicate at a turning point in devices that make up the Internet of Things.

    "In light of a long-promised future where interconnected, autonomous, widespread and unremarkable technologies make life easier, the networked devices available now, like video doorbells and app-enabled lights, seem like rather slight advances." the researchers said. They believe technologies like theirs could help cross the gap between the Internet of Things as we know it and the Internet of Things at its best-whatever that may be.

    Crossing your legs is an extremely common habit; most people don't even notice that they're doing it when they sit down. While you may find it comfortable to sit with one knee crossed over the other, it might be causing health problems that you are not aware of.

    A study published in Blood Pressure Monitoring stated that sitting with your legs crossed can increase your blood pressure. The reason for this is that the blood in your legs has to work against gravity to be pumped back to your heart and that crossing one leg over the other increases resistance(阻力), making it even harder for the blood to circulate. This causes your body to increase your blood pressure to push the blood back to the heart. You won't feel any immediate effects, but repeated, drawn-out increases in blood pressure can cause long-term health problems. So, planning to sit for a long period of time? Don't keep your legs crossed.

    Crossing your legs at the knee can also cause pressure on the major nerve in your leg that passes just below your knee and along the outside of your leg, explains Richard Graves, a medical expert. This pressure can cause numbness and temporary paralysis (麻痹) of some of the muscles in your foot and leg, preventing you from being able to raise your ankle—what we know as that “pins and needles” sensation. While the feeling of discomfort may only last a minute or two, repeatedly crossing your legs until they feel numb can cause permanent nerve damage.

    So next time you sit down, try to get yourself in the habit of sitting with both of your feet on the floor. Not only will it help your posture and stability, but it will also save your health in the long run.