In some science-fiction movies, robots refuse to die no matter how people fight back (反击). Now, it has turned into a fact. For the first time, researchers have created a robot that can take a beating (挨打) and keep on working. Developed by scientists from Cornell University and the University of Vermont, the new robot looks like a spider with four legs.

    Until now, even the most advanced robot was almost certain to break down when damaged. That's because its computer doesn't know how to operate the machine after its shape has been changed.

    To solve this problem, the scientists put some sensors (传感器) into the machine. The sensors can read how the machine is working and send signals to the computer.

    Using this information, the system follows a new way to tell the machine's shape at any given moment. The computer considers a lot of possible next steps, and it calculates how best to move the robot forward the longest possible distance, before trying to move it again.

    The new technology is a major advance in robotics (机器人技术), scientists say. It may someday help researchers create better artificial arms and legs that give new freedom to people who lack them. The new knowledge might also help scientists understand how people and animals tell their own sense of place in space.

     “Designing robots that can fit changing environments has been a difficult problem,” says scientist Olaf Sporns of Indiana University. “This work provides a new way toward solving this important problem.”

    When Carson Palmer, a professional American football player, hurt his arm a few years ago, he took a week off from throwing the football. But in his head, Palmer practiced every day. The following weekend, Palmer had the best game of his life.

    For more than a century, scientists have been trying to understand how this mental training works. In the 1930s, researchers proved by experiment that when you're imagining an action, your brain sends signals to your muscles(肌肉) which are too weak to tighten the muscles but might help train the body to perform. In other words, mental practice might create a pattern in your head, like an inner how-to guide for a particular skill.

    Sports psychologists have conducted hundreds of studies comparing imagined and physical practice for actions. On the whole, the research shows that mental training works. A 2012 study, for example, compared 32 amateur golfers who practiced hitting the balls to another 32 who merely held a golf club in their hands and visualized（想象）their swings. Under the same training rules, both groups improved their skills by getting the ball about 4 inches closer to the hole.

    Visualization has advantages over the real thing: You can do it anywhere, even when injured. It is safe-a major plus for high-risk performers such as gymnasts and surgeons. And you can practice for longer periods of time because you're not restricted by physical tiredness, That's not to say it's easy, we've had Olympic-level athletes sitting in our lab, visualizing the movements for two hours," says Tadhg Macintyre, a sports psychologist at the University of Limerick in Ireland. “When we're done, they're absolutely tired.”

    It doesn't work for everyone, though. "If you're a novice, the effect can be harmful,” warns Macintyre. If you're trying to visualize a free throw, and you don't even know the proper movement, then you're probably going to mentally practice the wrong skill.”

    Many years ago, when we were a young couple with two small children, aged 2 and 4, we were practically impecunious. My in-laws lived from hand to mouth, so we didn't expect any help from them. My parents lived a great distance away, and I was too ashamed to let them know about our situation.

    My husband was trying to earn a living with an old pick-up truck, carrying groceries for local shopkeepers, but it was constantly breaking down. It took almost all the money we had to have it fixed. The truck was also the only means of transportation for us.

    We lived in the countryside, and we always used the back door because the driveway led to it. One winter evening, I stepped outside to take a bag of trash to the barrel and almost tripped over something. It was nearly dark, and I had to bend down to see what it was. I could hardly believe my eyes. There sat a large basket loaded with food.

    It was heavy, so I called my husband to carry it into the house. Once inside, we discovered two loaves of bread, some butter, several cans of vegetables, a can of orange sauce, and a large turkey. There was so much that I can't remember it all, but it was everything we needed to fix a wonderful dinner—everything except potatoes.

    A little while later I remembered that I hadn't taken the trash to the barrel. By now it was dark, so I had to turn on the yard light —and that's when I spotted a small bag of potatoes sitting on the porch.

    That dinner was the best I can remember.

    We weren't able to thank our donators, though, because we never found out who had been so generous in helping a struggling young family. Whoever it was, we are forever grateful.

    I'm a storyteller. And I would like to tell you a few personal stories.

    I grew up reading British and American children's books. When I began to write, I wrote exactly the kinds of stories I was reading: All my characters were white and blue-eyed, they ate apples and talked a lot about the weather, despite the fact that I lived in Nigeria. We ate mangoes, and we never talked about the weather. Because all I had read were books in which characters were foreign, I had become convinced that books by their very nature had to have foreigners in them. Things changed when I discovered African books. Because of writers like Chinua Achebe and Camara Laye, I went through a mental shift in my idea of literature. I realized that people like me, girls with skin the color of chocolate, could also exist in literature. I started to write about things I recognized. So what the discovery of African writers did for me was this: It saved me from having a single story of what books are. The year I turned eight, we got a new house boy Fide from a nearby rural village. The only thing my mother told us about him was that his family was very poor. And when I didn't finish my dinner, my mother would say，"Finish your food! Don't you know? People like Fide's family have nothing." So I felt enormous pity for Fide's family. Then one Saturday, we went to his village to visit, and his mother showed us a beautifully patterned basket that his brother had made. I was astonished. It had not occurred to me that anybody in his family could actually make something. Their poverty was my single story of them.

    Years later, when I left Nigeria to go to university in the United States, my American roommate asked where I had learned to speak English so well, and was confused when I said that Nigeria happened to have English as its official language. What struck me was this: She had felt sorry for me even before she saw me. My roommate had a single story of Africa: a single story of catastrophe.

    Of course, Africa is a continent full of catastrophes. But there are other stories that are not about catastrophe, and it is very important, it is just as important, to talk about them. The consequence of the single story is this: It robs people of dignity. It makes our recognition of our equal humanity difficult. It emphasizes how we are different rather than how we are similar.

    So what if my mother had told us that Fide's family was poor and hardworking? What if we had an African television network that broadcast diverse African stories all over the world? What if my roommate knew about my Nigerian publisher, Muhtar Bakare, a remarkable man who left his job in a bank to follow his dream and start a publishing house? What if my roommate knew about my friend Funmi Iyanda, a fearless woman who hosts a TV show, and is determined to tell the stories that we prefer to forget?

    My Nigerian publisher and I have just started a non-profit called Farafina Trust, and we have big dreams of building libraries and providing books for state schools, and also of organizing lots of workshops in reading and writing, for all the people who are eager to tell our many stories.

    Stories matter. Many stories matter. Stories can break the dignity of a people, but stories can also repair that broken dignity. When we realize that there is never a single story about any place, we regain a kind of paradise.

When David Carter started to study art at The University of Texas (UT) at Austin in 1971, he had big dreams of becoming an artist or a writer. But his study came to a stop at 23 after he hurt his hand in an unpleasant event. He developed schizophrenia(精神分裂症) later and spent many years without a home.

Carter liked to spend time around UT, because he dreamt of being able to continue his study in the university and becoming a writer. After running into Carter many times, UT student Ryan Chandler decided to interview him for a project for the Daily Texan, the student newspaper of UT.

"I interviewed him on Austin's homeless problems. After I heard his story, we kept in touch and really became friends. I learned he wanted to get back to UT, so I decided to help him," said Chandler. "He had got 87 hours, very close to a degree. Now, with changing degree requirements, he only has 64 hours to go."

With the help of Chandler, who worked with the university office, Carter was assigned an adviser by UT's College of Fine Arts. "It' s the greatest gift I've ever received," Carter said. "He did what had to be done to get me back to school, and I couldn't have done it without him"

After seeing a magazine article about Carter, a UT schoolmate decided to pay his tuition fees (学费)without telling Chandler his name.

Doug Dempster, dean of the College of Fine Arts, said in a statement, "David Carter's decision to complete his degree is a testament (证明) to finishing well what was started, and stopped, even many years earlier. We welcome him back as we do many students each year whose education could not be completed easily. We're going to help him through his remaining course work."

Have you ever heard of invisible ink? You may have seen it in movies. When light is shone on the paper which invisible ink is written on, you can read it!

As magical as this seems, the change in color is due to science. The ink is absorbing higher energy light and giving lower energy light. This reaction is an example of fluorescence (荧光) .

Light is a very broad term that describes a range of electromagnetic rays, including gamma rays, infrared light (红外光) and ultraviolet light. One part of the electromagnetic visible light is the colors that we can see with the human eye. These rays travel in curvy lines and each type of the ray is characterized by a different wave pattern. For example, Gamma rays have a shorter wavelength than infrared light. Shorter wavelength is connected with higher energy, so gamma rays also have more energy than infrared light.

Corals (珊瑚) are animals that live underwater. And the corals in the Red Sea exhibit fluorescence. Why is this happening? Scientists have shown that fluorescent objects absorb higher energy light and release lower energy light. Since the corals of the Red Sea are deep in the water where there is very little visible light, scientists theorize that these corals absorb ultraviolet light and produce visible light. They have special photo proteins, which enable them to change invisible light to visible light.

Fluorescence is not just used to create pretty colors. Corals have developed photo proteins for a biological reason. The visible light is used by algae (海藻) , which are eaten by the coral, to make food through photosynthesis (光合作用). The visual character of these photo proteins could also be used for biomedical research. They can highlight cells and cell structures under a microscope.

Isn't it amazing that a simple organism that we don't think very much of is not only grand but could also have so many potential uses in medical research!