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    Measles(麻疹), which once killed 450 children each year and disabled even more, was nearly wiped out in the United States 14 years ago by the universal use of the MMR vaccine(疫苗). But the disease is making a comeback, caused by a growing anti-vaccine movement and misinformation that is spreading quickly. Already this year, 115 measles cases have been reported in the USA, compared with 189 for all of last year.

    The numbers might sound small, but they are the leading edge of a dangerous trend. When vaccination rates are very high, as they still are in the nation as a whole, everyone is protected. This is called “herd immunity”, which protects the people who get hurt easily, including those who can't be vaccinated for medical reasons, babies too young to get vaccinated and people on whom the vaccine doesn't work.

    But herd immunity works only when nearly the whole herd joins in. When some refuse vaccination and seek a free ride, immunity breaks down and everyone is in even bigger danger.

    That's exactly what is happening in small neighborhoods around the country from Orange County, California, where 22 measles cases were reported this month, to Brooklyn, N.Y., where a 17-year-old caused an outbreak last year.

    The resistance to vaccine has continued for decades, and it is driven by a real but very small risk. Those who refuse to take that risk selfishly make others suffer.

    Making things worse are state laws that make it too easy to opt out(决定不参加) of what are supposed to be required vaccines for all children entering kindergarten. Seventeen states allow parents to get an exemption（豁免), sometimes just by signing a paper saying they personally object to a vaccine.

    Now, several states are moving to tighten laws by adding new regulations for opting out. But no one does enough to limit exemptions.

    Parents ought to be able to opt out only for limited medical or religious reasons. But personal opinions? Not good enough. Everyone enjoys the life-saving benefits vaccines provide, but they'll exist only as long as everyone shares in the risks.

    Hello,everybody.Welcome to surf on a new Web site—SCIENCE NEWS FOR KIDS!

    Our goal is to offer timely items of interest to kids,accompanied by suggestions for hands on activities,books, articles,Web resources,and other useful materials.

    Our emphasis is on making the Web site attractive by offering kids opportunities to comment on and grade the subject matter,get ideas for science projects,and try out math puzzles.At the same time,we offer teachers creative ways of using science news in their classrooms.

    The Science News for Kids Web site,supported by several corporations and foundations,strengthens the usefulness of Science News in the middle－school classroom and offers entertaining reading and activities for students interested in science.

    A section of the Science News for Kids Web site is devoted to particular interests.At present,we have six such zones: a weekly brainteaser（难题）for those who enjoy solving and inventing puzzles (PuzzleZone),entertaining science－fiction composition exercises for those interested in writing (SciFiZone),and weekly science short description along with science project ideas and tips (ScienceFairZone).The GameZone contains a small selection of logic and memory games.The TeacherZone has materials,including question sheets related to the feature article of the week,so that teachers can bring science news topics to the classroom.The LabZone features a weekly hands on activity or science project idea.In the future,we might add additional zones,for example,for kids interested in robotics,the environment,computers,math,or veterinary（兽医的）medicine and animals.

    Contact us at editor@snkids.com.         Science News for Kids            1719 N Street,N.W.

    Washington,DC 20036                 Phone :202-785-2255             Fax: 202-659-0365

    "A photograph that one has taken of oneself, typically with a smart phone or webcam and uploaded to a social media website" is the definition of "selfie" in the Oxford English Dictionary. In fact, it wasn't even in the dictionary until August of last year. It earned its place there because people are now so obsessed with (对……痴迷) selfies—we take them when we try on a new hat, play with our pets or when we meet a friend whom we haven't seen in a while.

    But is there any scientific explanation for this obsession? Well, you should probably ask James Kilner, a neuroscientist(神经系统科学家) at University College London.

    Through our lifetime we become experts at recognizing and interpreting other people's faces and facial expressions. In contrast, according to Kilner, we have a very poor understanding of our own faces since we have little experience of looking at them—we just feel them most of the time.

    This has been proved in previous studies, according to the BBC.

    Kilner found that most people chose the more attractive picture. This suggests that we tend to think of ourselves as better-looking than we actually are. To further test how we actually perceive our own faces, Kilner carried out another study. He showed people different versions of their own portrait—the original, one that had been edited to look less attractive and one that was made more attractive—and asked them to pick the version which they thought looked most like them. They chose the more attractive version.

    But what does it say about settles? Well, isn't that obvious? Selfies give us the power to create a photograph—by taking it from various angles, with different poses, using filters (滤色镜) and so on—that better matches our expectations with our actual faces.

    "You suddenly have control in a way that you don't have in non-virtual(非虚拟的) interactions," Kilner told the Canada-based CTV News. Selfies allow you "to keep taking pictures until you manage to take one you're happy with", he explained.

    Although his 1-year-old smart-phone still works perfectly, Li Jijia already feels the need to replace it.

    "There are many better ones available now. It's time to upgrade(更新）my phone."

    Li's impatience is shared by many. Shortly after the season when new products are released（发布，发售）, many consumers feel the urge to upgrade their electronic equipment, even though the ones they have still work just fine.

    As consumers' minds are occupied by Apple's newly released products and debate whether the Google tablet is better than the new Amazon Kindle, it might be time to take a step back and ask: "Do we really need the latest upgrades?"

    According to Donald Norman, an American author, "planned obsolescence (淘汰）" is the trick behind the upgrading culture of today's consumer electronics industry.

    Electronics producers strategically release new upgrades periodically, both for hardware and software, so that customers on every level feel the need to buy the newest version.

"This is an old-time trick—they're not inventing anything new," Norman said. "This is a wasteful system through which companies--many of them producing personal electronics—— release poor-quality products simply because they know that, in six months or a year, they'll put out a new one."

    But the new psychology of consumers is part of this system, as Norman admitted, "We now want something new, something pretty, the next shiny thing." In its most recent year, Apple's profit margin(利润) was more than 21 percent. At Hewlett-Packard, the world's biggest PC maker, it was only 7 percent.

    Apple's annual upgrades of its products create sales of millions of units as owners of one year's MacBook or iPhone line up to buy the newest version, even when the changes are slight.

    As to Li Jijia, the need for upgrading his smart-phone comes mainly from friends and classmates. When they are switching to the latest equipment, he worries about feeling left out.

    "Some games require better hardware to run," said Li. "If you don't join in, you lose part of the connection to your friends."

    Feeding birds is a popular way to watch wildlife. But experts say it might put wild birds at risk.

    Feeding birds is not necessary for their survival except in extreme weather conditions. Feeders(喂食器)can definitely help birds get through that kind of weather. But most birds eat insects and show little interest in bird feeders. For those birds, we can grow native plants in a natural environment. Birds which are fond of eating seeds will be more likely to come to feeders if there is some cover nearby. This lets them feed and then fly to protective areas, such as in trees.

    The most common mistake people make with their bird feeders is that they put feeders in places where birds are easily frightened by passers-by, risk being hurt by cats, or risk flying into windows.

    So set up a bird feeder at least one meter away from a window. That way, if a bird gets frightened, it won't get killed when it hits the glass. Owners of cats should keep them inside home so they can't hurt the birds.

    Some birds are more aggressive at feeders. They eat a lot and do not leave much food for other birds. A solution is to put the food in more than one place by using different kinds of seeds or fruits. This can also increase the number and diversity of birds in your neighborhood. But don't feed wild birds anything salty, like potato chips, or food that could choke them, like bread.

    Pay attention to food quality and freshness. Unprotected food left too long in feeders will turn moldy(发霉), which can kill wildlife.

    Another word of advice: Always provide a supply of clean water for birds, but use care when looking for the right birdbath. If the birdbaths are too deep for birds, putting a few large stones in the water can give the birds a place to sit.

Simply being quiet is a growing appeal. Lots of business have appeared to meet a rising demand for quiet time, from silent weekend getaways to silent dining, silent reading parties and even silent dating. Silence can mean different things to different people. We are usually silent only with those closest to us. So there is something almost radical(不同凡响的)about the recent trend towards enjoying silence with strangers.

Mariel started a regular silent reading party in Dundee just under a year ago. Readers bring their books and meet in a bar, where they read together in silence for an hour or sometimes two and then put their books away to chat and have a drink. "When the reading party starts, everything goes quiet," says Mariel," It's a little bit surreal (超现实的), especially in what is usually a noisy bar. However, there is something special about sharing the silence with others. It offers a chance to escape from reality; everyone is so busy with work and with technology being ever present. An event like this gives people the opportunity to escape these things for a while."

Honi Ryan is an artist based in Berlin who began hosting silent dinner back in 2006. The rules of the dinner are: no talking, no using your voice, no reading or writing, trying to make as little noise as possible, not connecting with technology, and staying for at least two hours. So far she has taken her silent dinner project to Mexico, the US, Australia and China. "It's evident that the age-old connections we make over food do not depend on the words around it. Silence creates the space for the people and places involved to fill with whatever is needed; it is quite different from our usual social behaviors."