“Keep out or I'll chase you out! This is my property!” You hear this every spring. It is a long musical sound —a bird song! Birds use their songs to communicate different messages to one another. People who study bird sounds are learning their meanings.

    Usually it is the male that sings. Early in spring he sings to say that he has picked out a piece of property. He sings to attract a female of his same kind. Together they will raise a family in his territory (领地). He sings to tell all other birds of his kind to keep out.

    Each kind of bird has its own type of song. Cardinals sing something that sounds a little like “What cheer, cheer, cheer.” Towhees sing, “Drink your tea.”

    Most of the time, birds pay attention only to the songs of birds of their own kind. Cardinals answer cardinals, and song sparrows answer song sparrows. A cardinal knows that a song sparrow will not try to steal its mate. So you can see one reason why a cardinal may chase away another cardinal but will not bother a song sparrow.

    Most different kinds of birds eat different things. To find enough to eat, a bird needs a big piece of land to search in. Many kinds of birds have some ways of dividing up the land into territories. Song sparrows, cardinals ovenbirds, and white-throated sparrows are some of the birds that have territorial systems.

    Especially in early spring, birds work out the boundaries between their territories by singing “keep out” threats and by chasing and fighting each other. The birds continue singing to tell females that they have set up territories. Neighboring birds seem to agree that there are make believe fences between their pieces of property. Then they do not have to waste energy chasing each other instead of taking care of their young.

    Scientists guessed that some birds could recognize their neighbors by small differences in their songs. Two scientists who studied white-throated sparrows found that these birds can even tell the difference between songs of individual birds of their own kind. White-throated sparrows have songs that seem to say “I'm your neighbor” or “I'm a stranger” or “I'm your neighbor to the west.” Other kinds of birds could tell neighbors from strangers by their songs, too.

    We all know the feeling: looking at the computer screen, pretending to be interested in our homework, even though we really feel bored. But such feelings may soon be at an end, says Dr. Harry Witchel, head of the Essex Medical School. He believes that computers of the future will notice when people feel bored and even take action to stopit.

    Before you get concerned, the machine won't be reading your mind. It will be observing the many movements you make while using a computer. It's not interested in the big movements needed to use the machine — like moving a mouse or touching a screen — but small, barely noticeable movements like closing your eyes, moving in your seat or rubbing your face. Witchel calls these “boredom movements" and says they show how interested the person is in what they are reading or watching. The higher the interest level, the less movement!

    To test his theory, Witchel invited 27 people to perform various computer-based tasks. The activities ranged from playing online games (an interesting task) to reading documents like government laws that most people would find boring.

A special video camera followed the participants' movements as they completed each task. Just as the researcher expected, the “boredom movements" greatly decreased, by as much as 42%，when the subjects were very interested in what they were reading or seeing.

    Fortunately, Dr Witchel isn't planning to use his results to create machines that report students who are not paying attention at school. Instead, he wants “movement sensing” technology to be built into future computers in order to improve students' computer-based learning experience.

    The scientist says that by measuring the students' interest level as they work, educators will be able to adjust their materials in real-time to keep students focused. Witchel also believes that the technology can provide filmmakers with honest audience opinions and in the future, help to develop more intelligent robots.

    Reintroducing beavers (海狸) to Britain could help clean up rivers, prevent flooding and minimise soil loss, an expert has claimed.

    Professor Richard Brazier, a researcher at the University of Exeter, said unpublished results from a trial area in Devon showed muddy water entering an area where beavers were living was three times cleaner when it left. "Our trial has shown that the beavers are able to dam our streams in a way that keeps soil in the headwaters of our catchment (流域) so it doesn't block up rivers downstream and pollute our drinking and bathing waters. If we bring beavers back it's just one tool we need to solve Britain's crisis of soil loss and agricultural pollution of waterways, but it's a useful tool," he said.

    Prof Brazier's claims were disputed by the National Farmers' Union (NFU), which warned that the reintroduction of beavers to Scotland had led to fields and forests becoming damaged. Spokesman Mark Pope said: "The knowledge of the impacts beavers have had on farmland, riverbanks and flood defences in Scotland is concerning. We await the results of the Devon trial and will analyse the outcomes then."

    Prof Brazier, an expert in Earth Surface Processes, insisted the animals could even play a useful role in preventing flooding. He told BBC News: "The public is currently paying people to build leaky dams to keep storm waters in the uplands. The beavers can do it free of charge and even build their own homes."

    However, Professor Jane Rickson, a soil specialist from Cranfield University, Bedfordshire, joined the NFU in sounding a note of caution. She agreed that in some places in the UK there was evidence of worrying soil loss, and said new policies were urgently needed. Beavers may in fact reduce the river channel and remove vegetation, exposing banks to greater erosion (侵蚀) and increasing, rather than decreasing, the risk of flooding, she warned. And she said beaver dams should be "leaky" to avoid build-ups of large volumes of water.

    Making employees feel happy and healthy at work is good for many businesses. But it isn't always an easy thing. A study suggests that only 33% of the U. S. employees consider themselves fully engaged （投身于）in work, while 16% are greatly disengaged, and 51% are just showing up.

    But there is an exception. When it comes to employee engagement, it seems that employees in small companies are doing better. According to the same research, the largest U. S. companies are at the lowest levels of engagement, while companies with fewer than 25 employees are at the highest. And in one recent report, 75% of small business workers surveyed said they were "very" or "extremely" satisfied with their role as a small company employee.

    Unlike big companies, small companies are often short of resources but the employees can get more surprises there. Small companies offer excellent career opportunities to their employees. The bosses often know their staff very well and understand their personal needs. Employees of small companies are more likely to receive free meals, paid leave, and they can even bring their pets to work.

    But of course, there are many other draws in small businesses. One of the top draws is flexible scheduling (弹性工时). Another is being able to really see the fruits of one's labor. Besides, non-cash award is also a big draw. This could be something small that reflects employees' interests and lifestyles.

    While a parental leave might lead to some financial problems, small companies may do something to improve it. "It may be impossible for a five-person team to be reduced to four for six months," writes Camillia Velasquez, head of HR management platform, Justworks. "But it could be possible to allow new parents to take on reduced hours in a work-from-home environment." This kind of method has been realized in some small companies.

    Yesterday I cleared up my house and I mean really cleared up my house. The room that gave the most results was my husband's "office". There I found: one right-footed shoe, size 10 (he lost the other one somewhere), a set of Star Wars videos and two small china cats someone gave me last birthday. I collected these "finds" and took them downstairs and logged (登录）on to eBay: the answer to all our rubbish.

    What is eBay? It aims to provide a global trading platform where almost anyone can trade almost anything. The idea came from Pierre Omidyar. Born in Paris, Omidyar moved to Washington when he was still a child. At High School he became very interested in computer programming and after graduating from Tufts University in 1988, he worked for the next few years as a computer engineer. In his free time he started eBay as a kind of hobby, originally offering the service free by word of mouth. By 1996 there was so much traffic on the site that he had to upgrade and he began collecting fees. Joined by a friend, Peter Skoll and in 1998 by his dynamic CEO, Meg Whitman, he has never looked back. Even in the great dot-com crashes of the late 1990s eBay went from strength to strength. It is now one of the ten most visited online shopping sites on the Internet.

    If you think about it, it's a perfect Internet idea. All you have to do is take an e-photo, write a description, fill out a sales form and you're in business; the world is your market place.

    Some of the more bizarre goods up for offer have been a piece of French bread, partially eaten by Justin Timberlake, advertising space on a man's head, and a pair of used false teeth.

    One week later I am proud of having a clean and tidy home and € 110 in cash. Someone even bought the shoe.

    If you have never been on a cruise (乘船游览), it can seem like its own world—with its own rules and secret language. So here we are going to lay out the very basics of going on a cruise.

    Do I need a passport to go on a cruise?

    You may need a passport, but you should take one anyway. Besides the fact that you are going to need an ID card to board the ship in the first place, a lot of ports require one.

    How much luggage can I take on board?

    For the most part, cruise ships aren't like planes—there isn't a strictly regulated amount of luggage you can take with you, and you are not going to be charged for bringing too much. Keep in mind that cabin storage space can be tight. Everything, including your empty luggage, is going to have to fit inside and you don't want to be tripping over it for your whole vacation.

    Things like guns and knives are banned, but regulations vary from ship to ship about things like irons (generally a no) and hair dryers (generally a yes). Some ships allow you to bring a bottle of wine, but nearly all ban bringing your own hard alcohol.

    What's the process for boarding a cruise ship?

    Boarding a cruise ship is like boarding a plane—there are regulations or when to arrive, how to check-in, and what security you have to go through. Most cruise lines have transportation available from the airport; otherwise they normally own a paid parking lot where you can leave your car.