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.”

    As one of the world's oldest holidays, Halloween is still celebrated today in several countries around the globe, but it is in North America and Canada that it maintains its highest level of popularity. Every year, 65% of Americans decorate their homes and offices for Halloween. Halloween is the holiday when the most candy is sold and is second only to Christians in terms of total sales.

Austria

    In Austria, some people will leave bread, water and a lighted lamp on the table before retiring on Halloween night. The reason for this is that it was once believed such items would welcome the dead souls back to earth on a night which for the Austrians was considered to be brimming(溢)with strong cosmic energies.

Belgium

    The Belgians believe that it is unlucky for a black cat to cross one's path and also unlucky if it should enter a home or travel on a ship. The custom in Belgium on Halloween night is to light candles in memory of dead relatives.

Canada

    Modern Halloween celebrations in Canada began with the arrival of Scottish and Irish immigrants in the 1800s. Jack- O- Lantern is carved and the festivities include parties, trick-or-treating and the decorating of homes with pumpkins and corn stalks.

France

    Unlike most nation of the world, Halloween is not celebrated by the French in order to honor the dead and departed ancestors. It is regarded as an “American” holiday in France and was unknown in the country until around 1996.

    It is 2018; e-books are loved by many people. Do you read them?

    An e-book is an electronic book, which can be made from common books and loaded onto an e-reader. The e-reader is a mini-device, just like a cell-phone. It has a touch pad screen and can hold a few hundred e-books. People can read e-books on it just like they do a book. So it is possible for people to read anywhere with an e-reader. This is perfect news for people who love to read books but can't carry many.

    Another great thing is that people can read books on it quickly and there's no need for two hands to hold the book and turn pages. Most e-readers also have a nightlight, so you can read at night and don't wake your partner with a big light on.

    Not all book authors agree to make their books into e-books. The creator of Harry Potter says that her books will never be e-books. However, lots of authors absolutely love the idea and feel it's the next step to keep books alive.

    Nowadays e-books are sold in many websites, from where you can buy and load them onto your e-reader. Those websites look just like ordinary online bookstores and have a list of best sellers and a new book section. There is also a clear price on each e-book to make sure people can buy them like buying common books.

    You probably know that frogs hop (双足跳). But did you know that there's a small frog in the Pacific Northwest that belly flops (肚子先着水)? It's called a tailed frog.

    Dr. Rick Eisner, who has been studying tailed frogs for the past few years, says, "I've looked at thousands of jumps and have never seen them land on their feet like other frogs." Most of the time, tailed frogs land on their stomachs and then bring their back legs in to prepare for another jump.

    Eisner first noticed these frogs because of the way they swim. Other frogs kick both of their back legs at the same time. But when a tailed frog swims, it pushes first with one leg and then the other.

    To try to find out why tailed frogs bellyflop, Eisner and other scientists collected and filmed different kinds of frogs. They found that all of the frogs start their jumps the same way: They hold out their legs. The change comes in the landing. Tailed frogs can't move their back legs as quickly as other frogs do. Maybe they don't need to. Tailed frogs live around water and quickly jump into the water to escape danger.

    Early frogs developed around watery areas and could jump quickly into the water to escape danger. Scientists think those frogs blended in with (与…融合在一起) the green plants on the side of the rocky rivers, just like today's tailed frogs. "I would guess that other animals would have problems detecting them," explains Eisner. When other animals find those early frogs, the frogs could jump into the river. They didn't need to continue hopping.

    Tailed frogs and other kinds of frogs went their own ways about 200 million years ago. Tailed frogs stayed by rivers. Other kinds of frogs moved to places where new hopping skills allowed them to survive.

    People in Japan tend to live longer and stay healthier in their later years, with an increasing number of old people living alone. Japan is on a fast track to "ultra-age" with people aged 65 or above accounting for 28 percent of its total population in 2019；it was 26.7 percent in 2017. On the other hand, the number of births in 2019 fell to its lowest (about 941,000) since records began in 1899.

    Demand for care services for elderly people has increased. A shrinking (缩小) working population means fewer able-bodied adults are available to look after the elderly. State-provided facilities for the elderly are not enough which causes elderly people to turn to private ones but they are expensive.

    The country will be short of 380,000 of health nurses by 2025. The government has to turn to advanced robots to meet the shortage. A study found that using robots encouraged one third of the people to become more active and independent. Yet there is no robot that can provide the emotional support to the elderly.

    Japan provides a case study for China, which is also faced with a fast aging population. 17.23 million babies were born in China in 2019, about 630,000 fewer than in 2018. People aged 60 accounted for 17.3 of China's population in 2019. With a shortage of elderly care facilities and unbalanced supply, China may find it hard to deal with the rapidly increasing number of senior citizens.

    To meet the challenge, the Chinese government should make policy changes, which Japan is unwilling or unable to do or even consider. China should pay attention to the signals its aging population is sending and take proper and timely action.