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.

    When I was growing up，I was embarrassed to be seen with my father. He was badly crippled (跛脚)，and when we would walk together，his hand on my arm for balance，people would stare，I would be ashamed of the unwanted attention.

    It was difficult to walk together—and because of that，we didn't say much as we went along. But as we started out，he always said，“You set the pace. I will try to follow you.”

    Our usual walk was to or from the subway，which was how he got to work. He went to work sick，and even in bad weather. He almost never missed a day，and would make it to the office even if others could not. It was a matter of pride for him.

    When snow or ice was on the ground，it was impossible for him to walk，even with help. At such times my sister or I would pull him through the streets of Brooklyn，N.Y.，on a child's sleigh to the subway entrance. Once there，he would try to grasp handrail until he reached the lower steps that the warmer tunnel air kept ice free. In Manhattan the subway station was the basement of his office building，and he would not have to go outside again until we met him in Brooklyn on his way home.

    When I think of it now，I am surprised at how much courage it must have taken for a grown man to suffer from shame and disability. And I am also surprised at how he did it—without bitterness or complaint.

    He never talked about himself as an object of pity，nor did he show any envy of the more fortunate or able. What he looked for in others was a “good heart”，and if he found one，the owner was good enough for him.

    Now that I am older，I believe that is a proper standard by which to judge people，even though I still don't know exactly what a “good heart” is. But I know the times I don't have one myself.

    He has been away for many years now，but I think of him often. I wonder if he sensed my reluctance to be seen with him during our walks. If he did，I am sorry I never told him how sorry I was，how unworthy I was，how I regretted it. I think of him when I complain about my troubles，when I am envious of another's good fortune，when I don't have a “good heart”．

    A billionaire has recently made one of the biggest charitable（慈善的）donations to a university in China's history. Chen Tianqiao donated $115 million to the California Institute of Technology (Caltech) to help advanced brain research. The donation will be spent deepening the understanding of how the brain works. Chen has been interested in brain research, believing it can shape the industries such as artificial intelligence and virtual reality. However, this huge donation has caused heated discussions among Chinese scholars and internet users alike.

    Many criticized him for choosing to give money to a foreign university rather than home institutes for brain research, which are developing fast and are on track to catch up with the US in just a few years. Rao Yi, a biologist at Peking University, even said the donation was a typical mistake.

    Others, however, support his choice. They believe Caltech is a more reasonable choice compared with Chinese research institutions. Caltech has a long history and has taken a leading position in biology, and therefore it produces more efficient results. In addition, the results of the research benefit not only the American people, but also the rest of the world.

    A similar controversial case started two years ago when Pan Shiyi, chairman of SOHO China, donated $15 million to Harvard University to help disadvantaged Chinese students.

    Many believe that China is still behind in the management and use of donated money, and that as a result, Chinese charity donators are looking abroad. In comparison, Western countries like the US, which have a long history of donating money, have well-developed systems that use money efficiently. They can also provide full access for donors who want to track the use of the money. To get more donations, Chinese universities should be braver and more honest. They need self-reflection, rather than envy.

    Every morning my father buys a newspaper on his way to work. Every evening my mother looks through magazines at home. And every night, I look at the posters with photos of David Beckham and Yao Ming on my bedroom wall before I go to sleep. Can we imagine life without paper or print?

    Paper was first created about 2,000 years ago, and has been made from silk, cotton, bamboo, and, since the 19th century, from wood. People learned to write words on paper to make a book. But in those days, books could only be produced one at a time by hand. As a result, they were expensive and rare. And because there weren't many books, few people learned to read.

    Then printing was invented in China. When printing was developed greatly at the beginning of the 11th century, books could be produced more quickly and cheaply. As a result, more people learned to read. After that, knowledge and ideas spread quickly.

    Today information can be received online, downloaded from the Internet rather than found in books, and information can be kept on CD-ROMs or machines such as MP3 players.

    Computers are already used in classrooms, and newspapers and magazines can already be read online. So will books be replaced by computers one day? No, I don't think the Yao Ming poster on my bedroom wall will ever be replaced by a computer two metres high!

    A new study has found that social media could be affecting the sleep of young adults.

    The study is a project of researchers at the University of Pittsburgh's School of Medicine. They found that young people who often use social media are more likely to suffer from sleep disorders than those who use social media less. The researchers say doctors should ask young adults about their use of social media when treating sleep issues.

    "This is one of the first pieces of evidence that social media use really can influence your sleep." said Jessica C Levenson. She was the lead author of a report on the study.

    The researchers set out to examine the connection between social media use and sleep among young adults. Levenson noted that these young adults are possibly the first "generation to grow up with social media."

    The researchers wanted to find out how often young people used social media sites like Facebook, Twitter, Credit and Tumbler. For the study, they gave questionnaires to nearly 1,800 adults, aged 19 to 32. On average, members of the study group used social media sites one hour a day. They also "visited various social media 30 times per week."

    Thirty percent of the study's participants reported having serious problems with sleeping. Those people who used social media a lot were three times more likely to have a sleep disorder. And those who spent the most time on social media were two times as likely to suffer from sleep disturbances.

    Levenson said the number of times a person visits social media is a better predictor of sleep problems than overall time spent on social media. If this is true, she adds, then practices that stop such behaviors may be the most effective.

    Large gatherings such as weddings and conferences can be socially stressful. Pressure to learn people's names only adds to the stress. A new facial-recognition app could come to the rescue, .but privacy experts recommend going on with caution.

    The app, called SocialRecall, connects names with faces via smartphone cameras and facial recognition, potentially avoiding the need for formal introductions. "It breaks down these social barriers we all have when meting somebody," says Bany Sandrew, who Created the app and tested it at an event attended by about 10000 people.

    After receiving an invitation to download SocialRecall from an event organizer, the user is asked to take two selfies(自拍) and sign in via social median At the event, the app is active within a previously defined geographical area. When a user points his or her phone camera at an attendee's face, the app identifies the individual, displays the person's name, and links to his or her social media profile. To protect privacy, it recognizes only those who have agreed to participate. And the app's creators say it automatically deletes users' data after an event.

    Ann Cavoukian, a privacy expert who runs the Privacy by Design Center of Excellence praises the app's creators for these protective measures. She cautions, however, that when people choose to share their personal information with the app, they should know that "there may be unintended consequences down the road with that information being used in another context that might come back to bite you."

    The start-up has also developed a version of the app for individuals who suffer from prosopagnosia, or "face blindness", a condition that prevents people from recognizing individuals they have met. To use this app, a person first acquires an image of someone's face, from either the smartphone's camera or a photograph, and then tags it with a name. When the camera spots that same face in real life, the previously entered information is displayed. The collected data are stored only on a user's phone, according to the team behind the app.