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.”

    A new study shows students who write notes by hand during lectures perform better on exams than those who use laptops(笔记本电脑)．

    Students are increasingly using laptops for note­taking because of speed and legibility(清晰度)．But the research has found laptop users are less able to remember and apply the concepts they have been taught.

    Researchers performed experiments that aimed to find out whether using a laptop increased the tendency to make notes “mindlessly” by taking down word for word what the professors said.

    In the first experiment，students were given either a laptop or pen and paper. They listened to the same lectures and were told to use their usual note­taking skills. Thirty minutes after the talk，they were examined on their ability to remember facts and on how well they understood concepts.

    The researchers found that laptop users took twice as many notes as those who wrote by hand. However，the typists performed worse at remembering and applying the concepts. Both groups scored similarly when it came to memorizing facts.

    The researchers' report said，“While more notes are beneficial，if the notes are taken mindlessly，as is more likely the case on a laptop，the benefit disappears.”

    In another experiment aimed at testing long­term memory，students took notes as before but were tested a week after the lecture. This time，the students who wrote notes by hand performed significantly better on the exam.

    These two experiments suggest that handwritten notes are not only better for immediate learning and understanding，but that they also lead to superior revision in the future.

    Tang Dynasty poets sang for about three centuries in different tones. There were many famous poets living in the Tang period such as Li Bai, Du Fu, Bai Juyi and Li Shangyin. Poems of the Tang Dynasty edited in the Qing Dynasty is a collection of more than 48,900 poem that were written by over 2,200 poets. But it didn't cover all the poems of the Tang Dynasty.

    During the Tang Dynasty, poems were recited when lovers walked under the moonlight. Poems were also recited when soldiers fought on the battlefield. People recited them in the open air or at temple fairs.

    Tang Dynasty poets wrote poems to win fame and also to develop their temperament(性情). They poured out deep feelings for their friends and criticized in injustice in the world through poems.

    In the Tang Dynasty scholars had to be poets. Their readers were not only people of high social position but also common people. Poets recited poems, women singers sang poems and other ranks of people, including old women and children, read Tang poems. This atmosphere affected foreigners who visited the country at that time. As a result, Tang poetry was introduced to some adjacent countries, like Japan and Vietnam.

    Tang poetry is a most brilliant page in the history of ancient Chinese literature. It's a miracle in the cultural history of mankind. The Tang Dynasty was a powerful empire with a vast territory. It inherited(继承)Chinese civilization that went back to ancient times, was combined with the best of other cultures and adopted the benefits of other nations in the world. Tang poetry wasn't the only spiritual wealth created by the Tang Dynasty people. Philosophy and religion, handwriting and painting and music and dance all gained new peaks of development. Tang poetry, however, was the jewel in the crown and its greatest achievement.

    The lower East Side is neither rich nor beautiful, but it can be a good place to shop.

    On Sundays, its streets are crowded with visitors and shoppers like these. They are trying to find a coat or a pair of shoes at a good price.

    Most people prefer to shop in the big department stores like Macy's, Gimbel's, or Bloomingdale's because there they can find clothing, furniture, toys, and food in one store.

    Some people like the smaller stores of Greenwich Village or other areas when they are looking for an unusual present.

    Some streets have only one kind of stores. Bracelets (手镯) and rings shine in the windows of Canal Street, and wedding dresses fill the stores of Grant Street. There are streets for furs(皮大衣), and, in one area, there are 600 shops for antiques (古玩)! Fifth Avenue is the most famous place to shop, and it is usually the most expensive. There you can find the latest styles from Paris, Italy, or New York. You can spend thousands of dollars on Fifth Avenue, or you can just window shop and admire the sights for free.

    The first organized system for sending messages began in Egypt around 1500 B.C. This system developed because the pharaohs frequently needed to send messages up and down the Nile River in order to keep their empire running smoothly. Later, the Persians developed a more efficient system for sending messages using men and horses. Messages carriers rode along the road system stretching from one end of the Persian Empire to the other. Along these roads, fresh men and horses waited at special stations to take and pass along any messages that needed to be sent. The stations where riders passed messages back and forth were built 23 kilometers apart, so the men and horses were able to travel quickly between them. The Romans later took up his idea and improved it by using a more advanced and extensive road system.

    In China, however, Kublai Khan had built up his own system for delivering messages. This system worked in the same basic way as the Roman system. The difference was that Kublai Khan kept 300,000 horses along the roads of this delivery lines. There were over 10,000 stations where a message would be passed from one rider to another with a fresh horse. In this way, Kublai Khan could receive messages from anywhere in the country in only a few days.

    It was not until the 1500s that a well-organized postal system appeared again in Europe. One family, the von Taxis family, gained the right to deliver mail for the Holy Roman Empire and parts of Spain. This family continued to carry mail, both government and private, throughout Europe for almost 300 years.

    In 1653, a Frenchman, Renouard de Velayer, established a system for delivering post in Paris. Postal charges at that time were paid by the recipient, but de Velayer's system was unique by allowing the sender to pre-pay the charges, in a similar way to the modern stamp. Unfortunately, de Velayer's system came to an end when jealous competitors put live mice in his letter boxes, ruining his business. Eventually, government-controlled postal systems took over from private postal businesses, and by the 1700s government ownership of most postal systems in Europe was an accepted fact of life.

    The thing that all these early systems had in common was that they were quite expensive for public use, and were intended for use by the government and the wealthy. However, in 1840, a British schoolteacher named Roland Hill suggested introducing postage stamps, and a postal rate based on weight. This resulted in lowering postal rates, encouraging more people to use the system to stay in touch with each other, His idea helped the British postal system begin to earn profits as early as 1850. Soon after that many other countries took up Mr. Hill's idea. And letter writing became accessible to anyone who could write. Today, the Roland Hill awards are given each year to "encourage and reward fresh ideas which help promote philately"(stamp collecting).

According to a new research,the more people in a country who have a particular gene(基因),the happier the nation will be.This DNA is known as the FAAH gene.People with a particular version of it tend to be cheerier souls.There is a link between levels of the FAAH gene and the number of people who say they are very happy.

Sweden—one of the happiest countries in the world—also has lots of happy DNA.Ghana,Nigeria,Mexico and Columbia all come out near the top in the happiness league,and have high rates of the gene.In contrast,the people of Iraq,Jordan and China are among the least likely to rate themselves as very happy and also have the lowest level of the FAAH gene.

However,wealth and health are found to have little effect on happiness.The finding could help explain why some of the world's poorest nations are also the happiest.In addition,the FAAH gene and an optimistic attitude would not always go hand in hand.For example,Russians and Estonians score very low in happiness,despite having the right happy DNA.

Professor Michael Minkov said,"The climate condition is associated with the nation's happiness.We can notice the high occurrence of the FAAH gene in tropical(热带的) areas in the Americas and Africa.And the occurrence of the gene around the Mediterranean Sea is much lower than that in Northern Europe."

The social experts say that genetics is not the only determinant(决定因素) of happiness.The economic and political difficulties in some nations also contribute to the very low happiness scores.Nations that are not blessed with the right DNA aren't necessarily miserable.