Many people believe that you lose the ability to learn new languages as you get older. Language experts, however, will tell you that you're never too old to learn a new language. As you get older, it can be more difficult to learn a new language, though.

    Children and adults learn new languages in different ways. For children, language is their life. They study for thousands of hours every year, because they need to learn languages to become part of their communities. Adults, on the other hand, are already part of a language community. Learning a new language means becoming part of another language community, and adults rarely get the chance to practice as much as young children do.

    Moreover, children learning a new language are expected to make mistakes. This gives them freedom when learning to be daring and confident. Adults, however, often feel pressured to be perfect when learning a new language. This can discourage many people and make it even harder to learn a new language.

    When young children learn a new language, they come to see various languages as a “normal” part of society. This mindset （思维模式） helps them embrace learning a new language without feeling like they're doing something unusual or “too hard”.

    So if you want to learn a new language, go for it! It's never too late to learn a new language. If you're older, it may take more work, but it can be done. If you're a young child, though, now is the time to step out and learn a new language!

    Jayson McCarthy, 12, was born without fingers on his left hand. That didn't stop him from being able to do many tasks. But Jayson could not grasp more than one object at a time. So Jayson 's father, Paul, created a Prosthesis(假肢), using a 3D printer. Now Jayson has fingers that open and close. “It was a do－it－yourself, father－and－son adventure，” says Paul.

    When Jayson was a baby, his doctor advised his parents not to give him a prosthetic hand until he was in his early teens. “The doctor said Jayson should first learn to get full use out of the hand he was born with，” says Paul. As Jayson got older, his father looked into purchasing a prosthetic hand, which can cost as much as $30，000. Paul found a more affordable solution.

    One day, Paul discovered a video on the Internet about Robohand, a prosthesis created with a 3D printer. He downloaded the free instructions and called Robohand's creators for advice. They told him all he needed was a 3D printer—which costs around $2，000—and some materials.

    Luckily, Jayson 's school had recently purchased a 3D printer and it offered to help Paul build the hand for Jayson n. “We used a soccer shinguard(护胫), cardboard(硬纸板), and tape. They cost about $10，” says paul.

    With his new hand, Jayson can do things better. “I can help my mom more, because now I can carry two grocery bags，” he says.

    Jayson 's father has already built several hands for Jayson. Jayson helps design each one. He says there's one thing in particular that he wants to do with a future prosthesis. “The goal，” he says, “is to be able to tie my shoelaces(鞋带)．”

    “Now I just don't believe that.” Surely all of us, at some point, have watched a movie and thought: It's simply badly researched, or, the makers must think we're fools.

    If movies were completely scientifically accurate, they'd probably be as interesting as a Physics 101 lecture. In real life, there are no explosions in space, gas usually doesn't explode from a lit cigarette, and Bruce Willis/Jackie Chan/Will Smith would most likely be in a coma(昏迷) after getting kicked in the head.

    Recently, the British newspaper The Daily Telegraph ran a humorous piece on unconvincing tech moments from some top movies. Let's see what they are all about.

    Telegraph writer Tom Chivers' first example from the end-of-the-world movie Independence Day, in which a character comes up with a virus capable of destroying Windows, the computer system the alien(外星人) spacecraft uses. “It's a good thing they didn't have Norton antivirus,” jokes Chivers.

    It's just one case of a movie that takes a lot of license with its science. Another one Chivers mentions is from Star Wars, where glowing beams of light raveling through space look very impressive. The problem is that in space there are no air particles(颗粒) for the light to reflect off. In reality, they'd not be seen, which wouldn't look so cool on the big screen.

    Chivers' second piece of Star Wars nonsense is the sound the fighters make in the movies: “the bellow(咆哮) of an elephant mixed with a car driving on a wet road”. But sound needs a medium to travel through, like air. In space, there wouldn't actually be any sound at all.

    Few people would deny that the mind-bending Matrix films make for great viewing, but for Chivers, the science in the movies is a little silly.

    And finally, as Chivers points out, DNA is not replaceable. But this bit of elementary genetics passed the makers of the 2002 Bond film Die another Day by. In the film the villain(坏人) has “gene therapy” to change his appearance and his DNA, which is completely impossible.

    Almost every day we come across situations in which we have to make decisions one way or another. Choice, we are given to believe, is a right. But for a good many people in the world, in rich and poor countries, choice is a luxury, something wonderful but hard to get, not a right. And for those who think they are exercising their right to make choices, the whole system is merely an illusion, a false idea created by companies and advertisers, hoping to sell their products.

    'The endless choice gives birth to anxiety in people's lives. Buying something as basic as a coffee pot is not exactly simple. Easy access to a wide range of everyday goods leads to a sense of powerlessness in many people, ending in the shopper giving up and walking away, or just buying an unsuitable item that is not really wanted. Recent studies in England have shown that many electrical goods bought in almost every family are not really needed. More difficult decision-making is then either avoided or trusted into the hands of the professionals, lifestyle instructors, or advisors.

    It is not just the availability of the goods that is the problem, but the speed with which new types of products come on the market. Advances in design and production help quicken the process. Products also need to have a short lifespan so that the public can be persuaded to replace them within a short time. The typical example is computers, which are almost out-of-date once they are bought. This indeed makes selection a problem. Gone are the days when one could just walk with ease into a shop and buy one thing; no choice, no anxiety.

Isatou Ceesay was born in 1972 in a small village in Gambia, Africa. As a teenager, Ceesay was forced to drop out of school because of poverty. She carried some goods with many girls like her to sell in the market to raise herself At that time, the plastic bags, being strong and light, became popular in Gambia. The problem was that people did not reuse the bags and simply threw them behind their homes. Over time, the houses were surrounded by trash.

Ceesay lived in such an environment for many years. She kept learning from the surrounding environment and planned to take action to change. In 1997, she started a recycling movement called One Plastic Bag in Gambia. She educated women in Gambia to recycle plastic waste into income for themselves. In the beginning, the movement had a mission to educate their village colleagues about the need to reuse garbage and recycle plastic waste, rather than letting the garbage increase behind their homes.

Over time, the movement became big and able to support and provide income for women around. It was also able to greatly reduce plastic waste in Gambia. But the work of collecting trash turned to be taxing. During the rainy season, plastic waste became wet and difficult to take, and after that it still took patience to dry it before it could be processed.

Ceesay said, "As a habit, people are used to pouring their garbage behind their houses, and because it is not visible, they forget it. But the bad effects again knock on your door very quickly — dirty air, various diseases and so on. Of course, if one man's house is clean but his neighbor's is not, then the man is also not healthy."

For 17 years, Ceesay has contributed to one of the most important problems about the plastic waste. In 2012, she got the TIAW Difference Maker Award in Washington, DC, United States. Her story was written into a book, which inspires many others to join or become makers of change in their own communities.

When I teach research methods, a major focus is peer review. As a process, peer review evaluates academic papers for their quality, integrity and impact on a field, largely shaping what scientists accept as "knowledge"- By instinct, any academic follows up a new idea with the question, "Was that peer reviewed?"

Although I believe in the importance of peer review and I help do peer reviews for several academic journals-I know how vulnerable the process can be. 

I had my first encounter with peer review during my first year as a Ph. D student. One day, my adviser handed me an essay and told me to have my -written review back to him in a week. But at the time, I certainly was not a "peer"--I was too new in my field. Manipulated data （不实的数据） or substandard methods could easily have gone undetected. Knowledge is not self-evident. Only experts would be able to notice them, and even then, experts do not always agree on what they notice. 

Let's say in my life I only see white swans. Maybe I write an essay, concluding that all swans are white. And a "peer" says, "Wait a minute, I've seen black swans. "I would have to refine my knowledge. 

The peer plays a key role evaluating observations with the overall goal of advancing knowledge. For example, if the above story were reversed, and peer reviewers who all believed that all swans were white came across the first study observing a black swan, the study would receive a lot of attention. 

So why was a first-year graduate student getting to stand in for an expert? Why would my review count the same as an expert's review? One answer: The process relies almost entirely on unpaid labor. 

Despite the fact that peers are professionals, peer review is not a profession. As a result, the same over-worked scholars often receive masses of the peer review requests. Besides the labor inequity, a small pool of experts can lead to a narrowed process of what is publishable or what counts as knowledge, directly threatening diversity of perspectives and scholars. Without a large enough reviewer pool, the process can easily fall victim to biases, arising from a small community recognizing each other's work and compromising conflicts of interest. 

Despite these challenges. I still tell my students that peer review offers the best method for evaluating studies aird advancing knowledge. As a process, peer review theoretically works. The question is whether the issues with peer review can be addressed by professionalizing the field.