The sound of a mosquito can mean trouble in many parts of the world. The bite of the mosquito can be deadly. The insects carry serious diseases like malaria (疟疾). It is estimated that almost 630,000 people died from malaria and malaria­related causes in 2012, and most of these cases were in African countries.

    In the United States, a group of California scientists are working to develop a more effective and less costly substance (物质) to protect people from mosquitoes. The researchers are investigating the sense of smell in mosquitoes. They found the insects use the same receptor for identifying carbon dioxide in human breath as they do for the smell of our skin. Anandasankar Ray, who is leading the investigation, says scientists tested more than a million chemical compounds (化合物) until they found a substance called Ethyl Pyruvate. He says Ethyl Pyruvate makes the mosquitoes' receptors inactive. “When we apply Ethyl Pyruvate to a human arm and offer it to hungry mosquitoes in a cage, very few of the mosquitoes are attracted to the human arm because only a few of them are able to smell it out,” said Ray.

    Genevieve Tauxe, a member of the research team, says it was not easy to find the neurons (神经元) of noble cells that recognize both the smell of human breath and skin. “With the device used to examine the mosquito, we are able to insert a very small electrode (电极) into the part of the mosquito's nose, where its smelling neurons are and where the smell is happening,” said Tauxe.

    Anandasankar Ray says a product based on Ethyl Pyruvate may cost less to produce than DEFT, the most effective chemical treatment now in use. He says DEFT is too costly for most people who live in areas affected by malaria.

    “Perhaps by finding smells that can attack other target receptors, we will be able to improve upon DEFT and finally have the next generation of insect behaviour control products,” said Ray.

    Parents often think that time spent with their kids will gradually decrease in adolescence. But a new study suggests that while teens try to avoid spending a lot of time together with their parents, private parent-child meetings may actually increase in their early adolescent years. And that may raise a teenager's self-esteem (自尊) and social confidence, especially if it is the time that spent with Dad, the researchers added. The researchers created a long-term study in which they invited families in 16 school districts in central Pennsylvania to participate. In each family, a teenager, a younger sibling (兄弟姐妹), their mother and their father were interviewed at home and then asked about their activities and self-worth five times over a period of seven years.

    The study authors were surprised to discover that when fathers spent more time alone with their teenagers, the kids reported they felt better about themselves. Something about the father's role in the family seemed to improve self-esteem among the teenagers in the study, said study co-author Susan McHale, a professor of human development at Pennsylvania State University.

    “Time with Dad often involves joking, teasing, and other playful interactions. Fathers, compared to mothers, were more involved in leisure activities and had more peer-like interactions with their children, which is crucial for youth social development,” the study showed. But Marta Flaum, a psychologist in Chappaqua, New York, said, “How these findings reflect the real world is a real question. The sample in the study is so small and so unrepresentative of most families in the country today that I'm not sure how much we can generalize from it. In my community in Westchester County, I don't see parents and teenagers spend much time together at all. Parents are often working so hard and have less time to be together with their kids.”

    However, Flaum encourages parents to make time for their kids no matter how much work they have to do. “Research like this reminds us of how important it is. The time we have with them is so short,” she said.

People aren't walking any more—if they can figure out a way to avoid it.

    I felt superior about this matter until  the other day I took my car to mail a small parcel. The journey is a matter of 281 steps. But I used the car. And I wasn't in ay hurry, either, I had merely become one more victim of a national sickness: motorosis.

    It is an illness to which I had thought myself immune（免疫的）, for I was bred in the tradition of going to places on my own two legs. At that time, we regarded 25 miles as good day's walk and the ability to cover such a distance in ten hours as sign of strength and skill. It did not occur to us that walking was a hardship. And the effect was lasting. When I was 45 years old I raced –and beat—a teenage football player the 168 steps up the Stature of Liberty.

Such enterprises today are regarded by many middle-aged persons as bad for the heart. But a well-known British physician, Sir Adolphe Abrhams, pointed out recently that hearts and bodies need proper…… is more likely to have illnesses than one who exercises regularly. And wlaking is an ideal form of exercise— the most familiar and natural of all.

    It was Henry Thoreau who showed mankind the richness of going on foot. The man walking can learn the  trees, flower, insects, birds and animals, the significance of seasons, the very feel of himself as a living creature in a living world, He cannot learn in a car.

    The car is a convenient means of transport, but we have made it our way of life. Many people don't dare to approach Nature any more; to them the world they were born to enjoy is all threat. To them security is a steel river thundering on a concrete road. And much of their thinking takes place while waiting for the traffic light to turn green.

    I say that the green of forests is the mind's best light. And none but the man on foot can evaluate what is basic and everlasting.

    People have used pigeons to carry messages to one another for hundreds of years. In fact, pigeons were a common way to send messages right up through Would War II.

    In 1815, English troops were fighting Napoleon's forces in France, and the English were believed to be losing. A financial panic swept over London. Government bonds（债券）were offered at low prices. Few people noticed that Nathan Rothschild, an English banker, was snapping up these bonds when everyone else was trying to sell them. A few days later, London learned the truth: the Duke of Wellington had defeated Napoleon at the battle of Waterloo. The value of the bonds soared（暴涨）, and Rothschild became wealthy…all because his pigeons had brought him news of the victory before anyone else knew of it.

    Carrier pigeons were used by countries in both World War I and World War II. Not only were the birds often the fastest, most reliable way to send messages, they could also be used to reach soldiers far behind enemy lines, where radios and field telephone lines were useless. Since they could easily be released from airplanes or ships, every branch of the armed services used the birds.

    Carrying messages could be a dangerous job. Some pigeons performed with such bravery that they became famous and were even awarded medals. The most famous pigeon of all may have been Cher Ami. Stationed in France during World War I, he carried twelve important messages for American forces. On his last mission, though wounded, he carried a message that saved the lives of 194 American soldiers. For his amazing service, he was awarded the French “Croix de Guerre.”

    Today, modern communication methods can carry information from one place to another hundreds of times faster than a pigeon could do it. However, few people would argue with the fact that carrier pigeons — especially those that served in the military — have earned their place in history.

Foreign visitors to the UK might be disappointed when they learn that not everyone there speaks like Harry Potter and his friends. Usually, there's an assumption by many non-Brits that everyone in Britain speaks with what's known as a Received Pronunciation (RP, 标准发音) accent, also called "the Queen's English". However, while many people do talk this way, most Britons speak in their own regional accents.

    Scouse, Glaswegian and Black Country – from Liverpool, Glasgow and the West Midlands – are just three of the countless non-RP accents that British people speak with. There are even differences in accents between towns or cities just 30 kilometers apart. What is even more disappointing is that not speaking in a RP accent may mean a British person is judged and even treated differently in their everyday life.

    In a 2015 study by The University of South Wales, videos of people reading a passage in three different UK accents were shown to a second group of people. The group then rated how intelligent they thought the readers sounded. The lowest-rated accent was Brummie, native to people from Birmingham, a city whose accent is considered working class.

    However, there is no need to be disappointed though you are not speaking in an RP accent. In fact, doing the opposite may even give you strength.

Kong Seong-jae, 25, is an internet celebrity from Seoul. After studying in the UK, he picked up several regional accents. He's now famous for his online videos, where he shows off the various accents he's learned. "British people usually get really excited when I use some of their local dialect words, and they become much friendlier. I think it makes a bit of bond between local people and foreigners to speak in their local accent," he said.

    So if you're working on perfecting your British accent, try to speak like someone from Liverpool, Glasgow or Birmingham. You may not sound like Harry Potter, but you are likely to make more friends.

    What do you remember about your life before you were three? Few people can remember anything that happened to them in their early years. Adults' memories of the next few years also tend to be unclear. Most people remember only a few events—usually ones that were meaningful and distinctive, such as being hospitalized or the birth of a new baby.

    How might this inability to recall early experiences be explained? The passage of time does not account for it; adults have excellent recognition of pictures of people who attended high school with them 35 years earlier. Another seemingly reasonable explanation—that infants do not form enduring memories at this point in development—also is incorrect. Children two and a half to three years old remember experiences that occurred in their first year, and eleven month olds remember some events a year later.

    However, three other explanations seem more promising. One involves physiological changes relevant to memory. Maturation of the frontal lobes (额叶) of the brain continues throughout early childhood, and this part of the brain may be critical for remembering particular episodes in ways that can be recalled later. Demonstrations of infants' and very young children's long-term memory have involved their repeating motor activities that they had seen or done earlier, such as reaching in the dark for objects, putting a bottle in a doll's mouth, or pulling apart two pieces of a toy. The brain's level of physiological maturation may support these types of memories, but not ones depending on clear verbal descriptions.

    A second explanation involves the influence of the social world on children's language use. Hearing and telling stories about events may help children store information in ways that will endure into later childhood and adulthood. Through hearing stories with a clear beginning, middle, and ending children may learn to take out the idea of events in ways that they will be able to describe many years later. Consistent with this view parents and children increasingly engage in discussions of past events when children are about three years old. However, hearing such stories is not sufficient for younger children to form enduring memories. Telling such stories to two year olds does not seem to produce long-lasting verbalizable memories.

    A third likely explanation for infantile memory loss involves mismatch between the ways in which infants encode information and the ways in which older children and adults recall it. Whether people can remember an event depends critically on the fit between the way in which they earlier encoded the information and the way in which they later attempt to recall it. The better the person is able to reconstruct the perspective from which the material was encoded, the more likely that recall will be successful.