Bad news sells.If it bleeds,it leads.No news is good news,and good news is no news.Those are "the classic rules for the evening broadcasts and the morning papers.But now that information is being spread amt monitored（监控）in different ways,researchers are discovering new rules.By tracking people's e-mails and online posts,scientists have found that good news can spread faster and farther than disasters and sob stories.

    "The ‘if it bleeds 'rule works for mass media,"says Jonah Berger,a scholar at the University of Pennsylvania. "They want your eyeballs and don't care how you're feeling.But when you share a story with your friends,you care a lot more how they react.You don't want them to think of you as a Debbie Downer."

    Researchers analyzing word-of-mouth communication—e-mails,Web posts and reviews,face-to-face conversations—found that it tended to be more positive than negative,but that didn't necessarily mean people preferred positive news.Was positive news shared more often simply because people experienced more good things than bad things?To test for that possibility,Dr.Berger looked at how people spread a particular set of news stories: thousands of articles on The New York Times' website.He and a Penn colleague analyzed the "most e-mailed" list for six months.One of his first findings was that articles in the science section were much more likely to make the list than non-science articles.He found that science amazed Times' readers and made them want to share this positive feeling with others.

    Readers also tended to share articles that were exciting or funny,or that inspired negative feelings like anger or anxiety,but not articles that left them merely sad.They needed to be aroused（激发）one way or the other,and they preferred good news to bad.The more positive an article,the more likely it was to be shared as Dr.Berger explains in his new book,"Contagious: Why Things Catch On."

    Crown shyness(树冠羞避) is a mysterious natural phenomenon in which the crowns of some tree species do not touch each other, but get separated by a gap clearly visible from ground level. The effect usually occurs between trees of the same species, but has also been observed between trees of different species.

    There are many theories going around, most of which make sense, but no one has been able to prove without the shadow of a doubt why some trees avoid touching each other.

    In his 1955 book Growth Habits of the Eucalypts, Australian forester M.R. Jacobs writes that the growing tips of the trees are sensitive to abrasion(擦伤), which results in crown shyness phenomenon. This theory was also supported by Dr. Miguel Franco. Some experiments have shown that if trees displaying crown shyness are artificially prevented from swinging in the wind and touching each other, they gradually fill up the gaps between them.

    But while the above theory is arguably the most widespread, it's certainly not the only one. Some scientists have suggested that crown shyness is a mechanism to stop the spreading of leaf-eating insects. These pests have been known to work together and create structures that extend up to 10 cm off of tree branches in order to reach other plants, so the gaps are the trees' natural defense method.

    One Malaysian scholar studied many trees, but found no traces of abrasions, despite their clear crown shyness. Instead, he suggests that the growing tips of the trees were sensitive to light levels and stopped growing when they got too close to other trees. Plants are able to sense how close they are to other plants and in order to get more light, they give off some chemical element to stop other trees from growing too close.

    Whatever the reason, one thing is for sure: plants are more intelligent than people used to think.

    Chinese researchers say they have come up with a simple way to find out a person's biological age —how much the body has aged physically – through a urine (尿) test.

    Their findings will help researchers conduct numbers of ageing studies and even predict a person's risk of age-related diseases, according to a paper published in the journal Frontiers in Ageing Neuroscience.

    Another paper by researchers at the Beijing Hospital and the West China Hospital in Chengdu, Sichuan province, said on Tuesday that people aged at different rates due to changes in their genetic make-up and their environment.

    Chronological age – which is based on one's birth date —was not an exact measure of biological age so a more exact method was needed, the team said.

    Ageing is driven by the lifelong gradual accumulation(积累) of a broad variety of molecular (分子) faults in the body's cells. The team said they had identified a matter 8-oxoGsn that indicated increases in oxidative (氧化性) damage in urine as people's bodies aged.

    Cai Jianping, a co-author at the Beijing Hospital, said: “As we age, we suffer increasing oxidative damage and so the levels of oxidative matters increase in our body.” The team tested the levels of 8-oxoGsn in urine samples from 1,228 Chinese people aged two to 90 and concluded the marker helped accurately determine the stage of biological ageing in adults.

    They had previously found that 8-oxoGsn levels also increased with age in the urine of animals such as mice.

    The team has also developed a rapid analysis technique called ultra-high-performance liquid chromatography(层析法), which can process up to 10 urine samples an hour, according to the study.

    Black Friday is the day after Thanksgiving Day and the Friday before Cyber Monday in the United States. It is not a federal holiday, but is a public holiday in some states. Many people take a day of their annual leave on the day after Thanksgiving Day. Some people use this to make trips to see family members or friends who live in other areas or to go on vacation. Others use it to start shopping for the Christmas season. Many organizations also close for the Thanksgiving weekend.

    Shopping for Christmas presents is also popular on Black Friday. Many stores have special offers and lower their prices on some goods, such as toys. Public transit systems may run on their normal schedule or may have changes. Some stores extend their opening hours on Black Friday. There can also be congestion on roads to popular shopping destinations.

    Black Friday is one of the busiest shopping days in the USA. There are two popular theories as to why the day after Thanksgiving Day is called Black Friday. One theory is that the wheels of vehicles in heavy traffic on the day after Thanksgiving Day left many black markings on the road surface, leading to the term Black Friday. The other theory is that the term Black Friday comes from an old way of recording business accounts. Losses were recorded in red ink and profits in black ink. Many businesses, particularly small businesses, started making profits prior to Christmas. Many hoped to start showing a profit, marked in black ink, on the day after Thanksgiving Day.

    For years, decades in fact, I've puzzled over the response most people have when I tell them I mostly travel alone.

    "You're so brave!"

    Why is it that a woman travelling alone, as I have often done for months at a time, is perceived to be "brave", whereas men who travel alone are entirely unremarkable?

You are only brave when you are afraid of something but still do it anyway. I have never been afraid of travelling alone.

    The first time I travelled alone was when I was 19. I was due to travel in Europe with a friend at the end of the summer. She announced by letter two days before our departure that she would be leaving me halfway at Vienna. It was too late by then to rope in another friend, so it was either to go home after Vienna, or keep going by myself. I kept going. I got on trains by myself, checked into hostels by myself and found my way around by myself. It was weird at first, but later I stopped worrying about it.

    When I got back to Ireland after that trip, I felt proud of myself. I had done something I had assumed would be hard, and it had turned out to be not hard at all.

    That was three decades ago, and since then I have travelled all over the world, usually on my own. I still do what I did then, which is to keep a diary. The greatest gift of solo travel has been those I've met along the way. I may have set off alone each time but I've encountered many people who became important to me. I met my husband in Kathmandu, Nepal. I met lifelong friends in Australia, Poland, Hungary, Turkey, India, Indonesia and many other places.

    Americans think much about time .From children they learn to value( 珍惜) time .As children, they are taught to be on time to go to school, to work and to do everything .When they are having a good time , they say that time flies .When a person is dying, they say he is living on borrowed time.

    Time is money. Time is knowledge. Time is everything in America. A working American has to work hard for 8 hours a day or 40 hours a week. This is the working time. In his spare time, he also works hard for money .Even on Saturday and Sunday he also works hard as usual. In the street you can hardly see that a man walks slowly. They walk very fast. In fact, they are running.

    They love time because time can bring money and a lot of things .But sometimes they also hate time, because they feel they have become servants of the clock.