Most American students go to traditional public schools. There are about 88, 000 public schools all over the US. Some students attend charter schools.

    Charter schools are self­ governing. Certain companies operate some charter schools. They are similar in some ways to traditional public schools. They receive tax money just as other public schools do. Charter schools must prove to local or state governments that their students are learning. These governments provide the schools with the agreement called a charter that permits them to operate.

    Charter schools are different because they do not have to obey most laws that govern traditional public schools. Each school can choose its own goals and decide what to teach and how to teach them in their own way. Class size is usually smaller than in traditional public schools.

    The government strongly supports charter schools as a way to re­organize public schools, which are failing to educate students. But some education unions are against charter schools. One teachers' union has just released the results of the first national study, which compared the progress of students in both traditional schools and charter schools.

    The results of the study show that charter school students performed worse on math and reading tests than the students in traditional public schools.

    Some experts say the study is not fair because students in charter schools have more problems than students in traditional schools. Other education experts say the study results would make charter school officials realize that they should help their students make greater progress .

    On a Saturday morning earlier this September, the world got its first look at the Strati. This electric vehicle is unlike any other currently on the road. It rolls on four wheels, but its body and chassis(底盘) weren't built in a factory. Instead, Strati's designers used a technology called 3-D printing. It created those parts of the car in one piece, from the ground up.

    “Compared to a typical vehicle on the road, the Strati definitely looks different,” says Greg Schroeder, a senior research engineer at the Center for Automotive Research in Ann Arbor, Mich. He did not work on the new car. His organization studies trends and changes in th e auto industry.

    It took 44 hours to print the new car at the International Manufacturing Technology Show in Chicago. Over the next few days, the car's designers installed additional parts. These included the car's engine, brakes and tires. Then, early on September 13, Jay Rogers climbed into the car, started its engine and drove the vehicle onto the street. Rogers helped found Local Motors. It's the Arizona-based company behind the Strati. Two weeks later, his team printed a second Strati, and just as fast, at a fair in New York City.

    Justin Fishkin, a local Motors official, sees the Strati as a window into the future. Today, car buyers are limited in their choice of a vehicle. They can order only what car companies have already designed. But in the future, he says, you may be able to design your own car online and then get it printed to order.

    Manufacturing experts say 3-D printing has begun to revolutionize how they make things. The technology has been around for decades. But these machines used to be so expensive that only large companies could afford them. In the last few years, though, that has changed. Many of the machines are now inexpensive enough for small companies—or even individuals —to own. Some local libraries make them available to the public. High Schools are beginning to use them in classrooms. Wide access to these printers means people can now design and print a wide variety of new things.

    The car's printer is a one-of-a-kind device.

    The technology behind the 3-D printer used in Chicago is an example of additive manufacturing. This proce ss builds solid objects, slice by slice, from the bottom up. (“Strati” means layers, in Italian.) A mechanical arm moves a nozzle from one side to another, back and forth. As it moves, the nozzle deposits a liquid—often melted plastic or metal (but it could be food, concrete or even cells) —that quickly hardens or bonds to become solid or semi-solid. This creates a single, thin layer. Once a layer is complete, the printer starts depositing the next one.

     “There's a lot of interest in 3-D printing in the auto industry,” says Schroeder. Right now, the technology is particularly useful for building models of cars or car parts.

    To compete with current auto manufacturers, the 3-D printer would have to increase in a hurry, Schroeder says. By contrast, he notes, a Ford F-150 pickup truck rolls off an assembly line at a rate of roughly one per minute. To print as many Stratis would require many more printers. Schroeder says he doesn't see 3-D printing soon taking over for such high-volume manufacturing. But, he adds, “Who knows what will h appen in the long term?”

    Scientists at Oak Ridge National Laboratory in Tennessee designed the 3-D printer used in Chicago. Lonnie Love, a research scientist at the lab, led the effort.

    Additive manufacturing often is slow and expensive. It also may produce materials that are unreliable, Love says. So for two years, his team searched for ways to make 3-D printing better. They built new machines and tested them over and over.

    All of that work paid off: their new machine is fast and uses less expensive material than earlier printers. In addition, it prints a plastic embedded with fibers of carbon to produce a stronger material. This helps ensure the material won't crack or break under pressure.

    By 2050, a completely new type of human evolve as a result of extremely new technology, behavior, and natural selection. This is according to Cadell Last, a researcher at the Global Brain Institute, who claims mankind is undergoing a major “evolutionary transition”.

    In less than four decades, Mr. Last claims we will live longer, have children in old age and rely on artificial intelligence to do ordinary and boring tasks. This shift is so significant, he claims, it is comparable to the change from monkeys to apes, and apes to humans. “Your 80 or 100 is going to be so radically different than your grandparents,” Mr. Last says, who believes we will spend much of our time living in virtual reality. Some evolutionary scientists believe this age could be as high as 120 by 2050.

    Mr. Last claims humans will also demonstrate delayed sexual maturation, according to a report by Christina Sterbenz in Business Insider. This refers to something known as life history theory which attempts to explain how natural selection shapes key events in a creature's life, such as reproduction. It suggests that as brain sizes increase, organisms need more energy and time to reach their full potential, and so reproduce less.

    Instead of living fast and dying younger, Mr. Last believes humans will live slow and die old. “Global society at the moment is a complete mess,” he told MailOnline. “But in crisis there is opportunity, and in apocalypse (启示) there can be transformation. So I think the next system humanity creates will be far more sophisticated, fair, and abundant than our current civilization.”

    “I think our next system will be as different from the modern world, as our contemporary world is from the medieval (中世纪的) world. The biological clock isn't going to be around forever,” he added, and said that people could pause it for some time using future technology.

    The change is already happening. Today, the average age at which a woman in Britain has her first baby has been rising steadily stands at 29. 8. In the US, just one percent of first children were born to women over the age of 35 in 1970. By 2012, that figure rose to 15 percent.

    “As countries become socio-economically advanced, more and more people, especially women have the option to engage in cultural reproduction,” Mr. Last added. And as well as having more child-free years to enjoy leisure time, he believes artificial intelligence will make up the need for low-skill jobs. We may also spend a large amount of time living in virtual reality. “I'm not quite sure most people have really absorbed the implications of this possibility,” Mr. Last said.

    His views are detailed in a paper, titled “Human Evolution, Life History Theory, and the End of Biological Reproduction" published Current Aging Science.

    If a woman has an extra piece of cake，don 't blame it on greed, blame it on her brain.

Scientists have found that women's brains react to food very differently — and much more strongly — than men' s. Academics found that decades of dieting pressure on women and advertising have programmed certain parts of the female brain to react strongly when faced with any kind of food. Men，on the other hand, are not usually as obsessive (着迷的）about what they eat.

    Dr. Rudolf Uher and his colleagues at the Institute of Psychiatry in King's College London used brain scanning technology，known as functional magnetic resonance imaging ( FMRI)，to look at the brains of eighteen men and women.

    The volunteers were given images of food to look at, as well as food to taste. Their brain reactions were observed by the scientists. They found that the female brains reacted much more strongly than those of males. The same reaction did not happen when they were shown non-food images. The team believe this means women think more about food than men tend to. Dr. Uher said, “This could be related to biological differences between men and women. But the more likely explanation is that women have a more complicated reaction to food because of social pressure. ”

Professor Carey Cooper，psychology and health professor at Lancaster University，said，“for centuries women have had a providing role — preparing and cooking food for their families. And it's part of that role to make sure the food is safe. They will therefore be much more sensitive to food than men are, and I would not be surprised if that was now built into their DNA. If the female brain react to food because it historically has developed neural (神经的）pathways to do this, then food will be the way they express their stress. Food actually，is a comfort for women. ”

    But other experts have said that more research must be done before the results can be proved. American scientist Angelo del Parigi of the John B. Pierce Laboratory in New Haven, Connecticut, said, “Looking at an FMRI alone cannot make sure whether the stronger reaction in women is due to innate (天生的）differences or a learned process. ''

    Electronic book publishing has many of the same risks and opportunities as electronic music publishing. By delivering text direct to the reader's computer screen, the e-book could cut down costs, and allow creators to deal directly with their audience, by passing (绕开) traditional publishers and traders. But it also raises the possibility of mass piracy (盗版). Phil Rance, founder and managing director of Online Originals, a London-based e-book publisher, sums it up, "No one wants Napster (在线音乐服务) to happen to books."

    Indeed, the most popular MP3may have put the frighteners on an industry that generally operates some way behind the "bleeding edge". The Meta Group, a leading US-based market researcher, says publishers are far too concerned about protecting their rights, "We believe all the recent legal control over Napster is like putting a finger in a river that is already overflowing. Publishers need to deal with reality and come up with new ways to develop wide electronic distribution, asking the question: How can we use the certainty of wide distribution to our advantage."

    At the moment, most publishers would like to limit the use of e-books to the person who bought them, or to the computer used to download them. If that can be done, e-books become just an extra income stream in a publishing industry that would continue to operate the way it does today, according to Terry Robinson, business manager for Adobe's e-paper group. "If you've cracked the digital rights aspect, you've cracked the market." He says.

    Robert Nichols, Books Director at BOL agrees, "Rights management is absolutely important. Publishers just say that 'until copyright is secure, we are not going to talk'."

    When John was growing up, other kids felt sorry for him. His parents always had him weeding the garden, carrying out the garbage and delivering newspapers. But when John reached adulthood, he was better off than his childhood playmates. He had more job satisfaction, a better marriage and was healthier. Most of all, he was happier. Far happier.

    These are the findings of a 40­year study that followed the lives of 456 teenage boys from Boston. The study showed that those who had worked as boys enjoyed happier and more productive lives than those who had not. "Boys who worked in the home or community gained competence (能力) and came to feel they were worthwhile members of society, "said George Vaillant, the psychologist (心理学家) who made the discovery. "And because they felt good about themselves, others felt good about them."

    Vaillant's study followed these males in great detail. Interviews were repeated at ages 25, 31 and 47. Under Vaillant, the researchers compared the men's mental­health scores with their boyhood ­activity scores. Points were awarded for part­time jobs, housework, effort in school, and ability to deal with problems.

    The link between what the men had done as boys and how they turned out as adults was surprisingly sharp. Those who had done the most boyhood activities were twice as likely to have warm relations with a wide variety of people, five times as likely to be well paid and 16 times less likely to have been unemployed. The researchers also found that IQ and family social and economic class made no real difference in how the boys turned out.

    Working—at any age—is important. Childhood activities help a child develop responsibility, independence, confidence and competence—the underpinnings (基础) of emotional health. They also help him understand that people must cooperate and work toward common goals. The most competent adults are those who know how to do this. Yet work isn't everything. As Tolstoy once said, "One can live magnificently in this world if one knows how to work and how to love, to work for the person one loves and to love one's work."