"You see someone just sitting there, looking like they're stupid," explains teenager Manny Logan excitedly. "You just run up to them, slap(掌击) them and run off. It's funny."

    The 16-year-old Logan was describing "happy slapping". It's supposed to be fun but it's a new problem in Britain. Young people will attack passers-by while their friends record the whole thing on camera phones. It was first reported in south London six months ago. But, the practice has spread to other parts of the country and videos of attacks have become popular on the Internet.

    The young people are called "hoodies" because they usually wear a sweatshirt with a hooded top. The top can be used to cover the head or face.

    One study in England published earlier this year suggested that as many as one in four teenagers is an active offender. That includes both serious crimes and small acts like not paying for a bus ticket.

    The fear of youth crime has left some parts of towns empty of ordinary people.

    So, the British government declared war on public disorder last week. The Prime Minister has supported a decision by the country's biggest shopping centre in southeast of England to ban teenagers wearing hooded tops. The clothing helps troublemakers hide from the centre's cameras.

    This week, the government is going further. It plans to force teenage offenders to wear orange jackets while they do public service. The idea is to shame them in front of others.

    But some teenagers and experts have complained that, in their rush to stop the hoodies, politicians risk tarring all teenagers with the same brush.

    Animals, including insects, do not have a language like ours. They do not talk to each other in words and sentences. But if we watch them, we can see that they do have ways of communicating with each other.

    Can you see the rabbits' tail? When rabbits see this white tail moving up and down, they run too. The rabbit has reminded them of potential dangers without making a sound. It has given them a signal.

    Many other animals use this kind of language. When a cobra (眼镜蛇) is angry, it raises its hood (兜帽) and makes itself look fierce. This warns other animals. When a bee has found some food, it goes back to its home. It cannot tell the other bees where the food is by speaking to them, but it does a little dance in the air. This tells the bees where the food is.

    Some animals say things by making sound. A dog barks, for example, when a stranger comes near. A cat purrs (猫的呜呜声) when pleased. Some birds make several different sounds, each with its own meaning. Sometimes we human beings speak in the same way. We make sounds like “Oh” or “Ah!” when we are frightened or pleased or when we drop something on our toes.

    But we have something that no animals have — a large number of words which have the meanings of things, actions, feeling or ideas. We are able to give each other all kinds of different information in words and sentences, which no other animals can do. No other animals have so wonderful a language as we have.

    It happens from time to time: you feel terrible when you take your first bite of a certain food, but after eating more, you find yourself enjoying it. This is what is called an acquired taste. But why do our tastes change?

    The answer, according to a recent study presented at an American Chemical Society meeting in Boston, lies in proteins in our saliva (唾液).

    Most of us tend to think saliva, almost entirely made up of water, is “only a mouth lubricant (润滑剂) helping us to swallow food,” the New York Times said. However, it also contains many proteins, which can help break food down, protect our teeth and help in tasting food.

    To explain how these proteins affect taste, a team of scientists from Purdue University in the US invited 64 volunteers to drink a bitter-tasting chocolate milk three times a day for six weeks and rated their tastes at the same time.

    According to the research, the participants found a strong bitterness on the first day, but the unpleasant flavor came to decrease as time went on and finally disappeared.

    That is not all that was changing. A noticeable increase in the levels of proline-rich (富含脯氨酸的) proteins was found in the saliva samples of the test subjects in the research period. These proteins serve to reduce the bitterness we taste and improve our adaptation to this flavor.

    “We think the body adapts to reduce the negative feeling of these bitter compounds,” said Cordelia Running, a food scientist at Purdue University. “Saliva changes flavor, which in turn changes eating choices.”

    This change in taste not only makes the food tastier, but also helps people keep an appetite for healthy food whose flavor might otherwise keep them away.

    One day, these proteins may even be extracted (提炼) and used as a separate food additive that could help people stick to healthy food whose flavor they continue to dislike, researchers told Science Alert. And according to Running, even it doesn't happen, the idea that “maybe some little piece of your body is actually trying to help you” could really benefit some people. Let's wait and see.

    Wood has many great characteristics that make it the perfect building material. It is cheap, durable, easily available, and most importantly, environmentally sustainable. The one thing it is not, is transparent! Now thanks to a team of scientists at Stockholm's KTH Royal Institute of Technology the material may even be able to add that feature to its already impressive list.

    Lead researcher Dr, Lars Berglund said he was inspired to create the transparent wood after learning how Japanese researchers had developed a see-through paper for use in flexible display screens for electronic devices. The team began by pulling out the wood's lignin(木质素). The lignin-free wood was then dipped into a polymer(聚合物)and baked at a temperature of 158°F for four hours. The result was a hybrid product that was not only stronger and lighter than the original wood but also, almost transparent. The researchers were able to adjust the level of transparency by varying the amount of the polymer injected and also by changing the thickness of the wood.

    While scientists have previously created a see-through wood for small-scale applications like computer chips, the transparent wood is the first one being considered for large scale applications. The researchers, who revealed their findings in Biomacromolecules on April 11, picture using the transparent wood in buildings to allow for more natural light, or to create windows that let in the desired amount of light without sacrificing privacy.

    Wood that allows light to pass through could lead to a brighter future for homes and buildings. Berglund also thinks the wood could play a significant role in the design of solar panels. The semitransparent material would be able to keep light longer and give it more time to interact with the conductor, thus resulting in better solar efficiency. Additionally, substituting the currently used glass with this new product would help solar energy manufacturers improve their carbon footprint and lower the cost. They are now experimenting with ways to scale up the manufacturing process so that the transparent material is cost-effective to make and easy to use.

    A project in Gambia is empowering women and reducing dangerous waste at the same time.

    The Waste Innovation Center, funded by the European Union's Global Climate Change Alliance, shows women in the Brikama area how to recycle waste into useful materials and products, which they can then sell in local markets.

    Wood-like waste is recycled into charcoal (木炭), for example, which can be used to supersede firewood and reduce the number of trees that are cut down for firewood. Food waste is recycled into compost(混合肥料)to function as environmentally friendly fertilizers and plastic is turned into many useful things.

    Supported by Waste Aid UK and the Gambia Women's Initiative (GWI), among others, the project provides women with skills they can use to become self-sufficient (自给自足的). Women learning at the center come from five communities, and some of them travel as far as 12 miles to learn these important skills that will provide them with an income, according to The Guardian.

    Isatou Ceesay, who now leads the GWI, highlighted the need to focus on economic equality in her country, telling The Guardian, "In terms of education, women are the ones who are always behind. Boys are chosen to go to school. When we conduct our training, we find women can do a lot, but don't know who they are, or how to carry out things. "

    According to the World Health Organization's Country Cooperation Strategy 2018—2023 report, the main environmental issue facing Gambia is poor waste management in urban areas. Ndey Sireng Bakurin, executive director of the National Environment Agency, has voiced concern over health and environmental risks, such as water pollution, the increase of insects as well as flooding that occur as a result of poor waste management.

    More than 20 years ago, a skeleton called Little Foot turned up in a South African cave. The nearly complete skeleton was a member of the human family. Now researchers have freed most of the skeleton from its stony shell and analyzed the fossils (化石) and they say 3.67-million-years-old Little Foot belonged to a unique species.

    Researcher Ronald Clarke and his colleagues think Little Foot belonged to A. Prometheus (普罗米修斯南猿). Clarke works at the university of the Witwatersrand in Johannesburg South Africa. He studies fossilized humans and our relatives. Their foundings, published in four papers, have suggested the species A.Prometheus might have existed. Clarke has believed in that species for more than a decade, he found the first Little Foot's remains in a storage box of fossils in 1994. People began digging out the rest of the skeleton in 1997.

    Many other researchers instead argue that Little Foot likely belonged to a different species, which is known as A.africanus (南方古猿非洲种). Researcher Raymond Dart first identified A.africanus in 1924. He was studying the skull (头颅骨) of an ancient youngster called the Taung Child. Since then, people have turned up hundreds more A. africanus fossils in South African caves. Those include Sterkfontein, where Little Foot was found.

    The braincase is the part of the skull that holds the brain. And researchers found a partial braincase that Dart thought belonged to a different species in Makapansgat, one of those other caves. In 1948, Dart called this other species A. Prometheus, but he changed his mind after 1955. Instead, he said that braincase and another fossil at Makapansgat belonged to A.africanus. There was no A. Prometheus after all, he concluded.

    Clarke and his colleagues want to bring back the rejected species. They say Little Foot's distinctive skeleton, an adult female that is at least 90 percent complete, is solid evidence for it.