A team of engineers at Harvard University has been inspired by Nature to create the first robotic fly. The mechanical fly has become a platform for a series of new high-tech integrated systems. Designed to do what a fly does naturally, the tiny machine is the size of a fat housefly. Its mini wings allow it to stay in the air and perform controlled flight tasks.

    “It's extremely important for us to think about this as a whole system and not just the sum of a bunch of individual components (元件),” said Robert Wood, the Harvard engineering professor who has been working on the robotic fly project for over a decade. A few years ago, his team got the go-ahead to start piecing together the components.“The added difficulty with a project like this is that actually none of those components are off the shelf and so we have to develop them all on our own,” he said.

    They engineered a series of systems to start and drive the robotic fly. “The seemingly simple system which just moves the wings has a number of interdependencies on the individual components, each of which individually has to perform well, but then has to be matched well to everything it's connected to,” said Wood. The flight device was built into a set of power, computation, sensing and control systems. Wood says the success of the project proves that the flying robot with these tiny components can be built and manufactured.

    While this first robotic flyer is linked to a small, off-board power source, the goal is eventually to equip it with a built-in power source, so that it might someday perform data-gathering work at rescue sites, in farmers' fields or on the battlefield. “Basically it should be able to take off, land and fly around,” he said.

    Wood says the design offers a new way to study flight mechanics and control at insect-scale. Yet, the power, sensing and computation technologies on board could have much broader applications. “You can start thinking about using them to answer open scientific questions, you know, to study biology in ways that would be difficult with the animals, but using these robots instead,” he said. “So there are a lot of technologies and open interesting scientific questions that are really what drives us on a day to day basis.”

    Deserts are found where there is little rainfall or where rain for a whole year falls in only a few weeks' time. Ten inches of rain may be enough for many plants to survive if the rain is spread throughout the year. If it falls within one or two months and the rest of the year is dry, those plants may die and a desert may form.

    Sand begins as tiny pieces of rock that get smaller and smaller as wind and weather wear them down. Sand dunes (沙丘) are formed as winds move the sand across the desert. Bit by bit, the dunes grow over the years, always moving with the winds and changing the shape. Most of them are only a few feet tall, but they can grow to be several hundred feet high.

There is, however, much more to a desert than sand. In the deserts of the southwestern United States, cliffs (悬崖) and deep valleys were formed from thick mud that once lay under a sea more than millions of years ago. Over the centuries, the water dried up. Wind, sand, rain, heat and cold all wore away at the remaining rocks. The faces of the desert mountains are always changing –-very, very slowly —as these forces of nature continue to work on the rock.

    Most deserts have a surprising variety of life. There are plants, animals and insects that have adapted to life in the desert. During the heat of the day a visitor may see very few signs of living things, but as the air begins to cool in the evening, the desert comes to life. As the sun begins to rise again in the sky, the desert once again becomes quiet and lonely.

    Do you want to learn English better?If you do,the following classes might be suitable for you.

Junior Courses

    Our English courses for juniors arc good for all the young people who want to develop their English language skills by taking part in exciting cultural and social activities.We offer this course to groups at every LSI school year found.We accept individual（个人的）young learners in our schools in the UK,the USA and Canada in our summer and winter camps.

    Teaching methods and social activities in the junior course are specially designed to suit kids and teenagers.Our English for junior courses are a great way for learners to make friends with other teenagers from all over the world.LSI offers English language courses to suit all abilities and levels.

Evening Classes

    LSI offers general language classes and exam classes in the evening.Students can take evening classes at a number of different LSI schools around the world.LSI London Central has a special foreign language department which offers classes in over 40 languages.Evening language classes are taught in open groups at LSI school buildings.We also organize language training that can be arranged either in or outside the school at any time for individuals and closed groups.

    Our evening language courses are for everyone.We train business people who require language skills for specific purposes and those who expect to gain some basic survival skills for their holidays.We provide quality training for all students at all levels,whatever their purposes are.

    Peter Skyllberg, a Swedish man, was trapped in his car for two months, with temperatures reaching -30^oC, with no food or water, and yet he survived. The best explanation was that his vehicle created an “igloo (snow house) effect” and protected him from the extremely low temperatures and that his body would hibernate(冬眠) during this time.

    Can humans get into a low-energy consumption state like a bear by reserving energy, and reducing body temperature? Chinese scientists are looking for the key to regulating body temperature.

    Scientists have found the hypothalamus (下丘脑), an area in the central lower part of the brain, is responsible for regulating body temperature. Wang Hong, a brain scientist at the Shenzhen Institutes of Advanced Technology of the Chinese Academy of Sciences, led her team to mark the neurons (神经元) responsible for regulating body temperature in mice by means of a cutting-edge genetic biology technique. In the experiments, they injected (注射) drug into mice to make the body temperatures of the mice drop rom 37℃ to 27 in two hours. The team found the change in body temperature caused no harm to the health of the mice. “We don't know if we can develop a drug that can control human body temperature. We still need a lot of study.” Wang said.

    Chinese scientists are not alone in such research. Body-cooling techniques are being used in pioneering hospitals around the world. Dutch doctors are now using low temperatures for patients who have suffered brain injuries in accidents, According to doctors working in Florence, it may even help to save the brains of babies who are born suffering from severe epileptic fits (癫痫病发作).

    The meaning of the word "volunteer" may be a little different in different countries, but it usually means "one who offers his or her services". There are many different ways in which people can volunteer, such as taking care of sick people, working in homes for homeless children, and picking up garbage from beaches and parks. Volunteers may work within their own countries or in other countries. They are often people with a strong wish to help those who are less fortunate than themselves. Volunteer don't expect any kind of pay.

    At the root of volunteering is the idea that one person may have the ability to offer services that can help other people. Tracy, a good friend of mine, however, recently came back from India with a new idea of what being a volunteer means. She worked for two and a half weeks in one of Mother Teresa's homes in Calcutta. The following is her story.

    "I first heard about Mother Teresa in my high school. We watched a video about her work in India and all over the world. I was so moved by her spirit to help others and her endless love for every human being that after I graduated from high school, I also wanted to try her kind of work. So with two friends, I flew to Caltutta for a few weeks."

    "I was asked to work in a home for sick people. I helped wash clothes and sheets and passed out lunch. I also fed the people who were too weak to feed themselves and tried to cheer them up. I felt it was better to share with them than to think that I have helped them. To be honest, I don't think I was helping very much. It was then that I realized that I had not really come to help, but to learn about and experience another culture that helped improve my own understanding of life and the world."

    A study based on data gathered by a NASA sensor has revealed China and India, the world's two most populous countries, are primarily responsible for making the Earth greener over the past two decades.

    The study, published on Feb 11 in the journal Natural Sustainability, has found that since 2000 the Earth's green leaf area has increased by over 5 million square kilometers. That's an area equivalent to the total of the Amazon rainforests. "China and India account for one-third of the greening, considering the general idea of land degradation (退化) in populous countries from overexploitation," said Chen Chi from Boston University, lead author of the study.

    The effect mainly comes from ambitious tree-planting programs in China and intensive agriculture in both countries, NASA said in a statement. China is the source of a quarter of the planet's increase in forest area, despite having only 6.6 percent of the world's vegetated (固定植被的)area, according to the study. Forest conservation and expansion programs account for 42 percent of the increase, and another 32 percent come from intensive agriculture of food crops, NASA said. While raising their green leaf areas, China and India have also greatly increased their food production through" multiple cropping" practices, where a field is replanted and crops are harvested several time each year. "Production of grains, vegetable, fruits and more have increased by about 35 to 40 percent since 2000 to feed their large population," NASA said.

    Over the past decades, China has made great efforts to green the land. In 1978, the central government launched a national-level forestation project-the Three North Shelterbelt Forest Program. By the end of 2017, the forest coverage rate among the regions in the project reached 13.57 percent, compared to 5.05 percent 40 years ago. In a greening project, Kubuqi Desert, seventh largest in the country, has seen one-third of its area covered by vegetation during the past three decades thanks to forestation efforts.