“A photograph that one has taken of oneself, typically with asmart phone or webcam and uploaded to a social media website” is the definitionof “selfie” in the Oxford English Dictionary. In fact, it wasn't even in thedictionary until August of last year. It earned its place there because peopleare now so obsessed with (对……痴迷) selfies ─ wetake them when we try on a new hat, play with our pets or when we meet a friendwhom 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) atUniversity College London.

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

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 weactually are. To further test how we actually perceive our own faces,Kilner carried out another study. He showed people different versions of theirown portrait ─ the original, one that had been edited to look less attractiveand one that was made more attractive ─ and asked them to pick the versionwhich they thought looked most like them. They chose the more attractiveversion.

But what does it say about selfies? Well, isn't that obvious?Selfies give us the power to create a photograph ─ by taking it from variousangles, 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 innon-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”, heexplained.

    A business executive（主管）was deep in debt and could see no way out. He sat on the park bench, head in hands, wondering if anything could save his company.

    Suddenly an old man appeared. “I can see that something is troubling you,” he said. After listening to the executive's words, the old man said, “I believe I can help you.” He asked the man his name, wrote out a check, and pushed it into his hand saying, “Take this money. Meet me here exactly one year from today, and you can pay me back at that time.” Then he turned and disappeared as quickly as he had come.

    The executive saw a check for $ 500,000, signed by John D. Rockefeller, then one of the richest men in the world! “I can settle all my debts immediately!” he realized. But instead, the executive decided to put the uncashed check in his safe. Just knowing it was there would give him the strength to work out a way to save his business, he thought.

    With renewed optimism, he made better deals and extended terms of payment. Within a few months, he was out of debt and making money once again. Exactly one year later, he returned to the park with the uncashed check. At the agreed-upon time, the old man appeared. But just as he was about to hand back the check and share his success story, a nurse came running up and grabbed the old man.

    “I'm so glad I caught him!” she cried.” hope he hasn't been bothering you. He's always escaping from the rest home and telling people he's John D. Rockefeller.” And she led the old man away. The astonished executive just stood there.

    Suddenly, he realized that it wasn't the money, real or imagined, that had turned him around. It was his newly found self-confidence that gave him the power to achieve anything he went after.

    “Why do I live? Why do I wish for anything, or do anything? Is there anything in my life that will not be destroyed by my death?”

    These are the words of the famous Russian writer Leo Tolstoy. Like Tolstoy, many people ask these difficult questions. And they struggle to find meaning in their life. Tolstoy spent his whole life trying to answer difficult questions like these. His search for answers influenced his writing.

    On August 28th, 1828, Leo Tolstoy was born in the country of Russia.

    As a child, Tolstoy was a member of the Russian Catholic Church. But as a young man, he began to question that faith. Tolstoy wanted to make his own moral decisions; he was tired of being told what to believe. He thought people could achieve a degree of perfection if they tried hard enough. So he worked very hard at being the best in everything he did. He thought that he would find meaning and truth in success.

    In the 1850s, Leo Tolstoy wrote his first stories. He wrote about his experiences in the army He also told stories about when he was a child. These works were published and Tolstoy became a well-known writer.

    Tolstoy was finally successful. He earned the respect he always wanted. Many wealthy and intelligent men met and talked with Tolstoy. Some of the men were writers like him. They talked a lot about faith and the meaning of life. But soon Tolstoy recognized that these men were not perfect. Now he knew they could not answer his questions about faith.

    So in the 1860s, Tolstoy tried a different way to find meaning. He opened a school for the children of his serfs -the people who worked on his land. These workers were very poor. He wanted to help them because he thought they were more honest than the wealthy people he knew.

    Tolstoy learned many things from his workers. He respected how they worked hard to provide for their families. He began to believe that marriage and family would give his life meaning. So in 1862, Leo Tolstoy married a young woman named Sonya Behrs.

    The next 15 years were the best years of Tolstoy's life. It was during this time that he wrote his most famous books -War and Peace and Anna Karenina. Many literature experts say that War and Peace is one of the greatest books ever written.

    Both War and Peace and Anna Karenina communicate Tolstoy's beliefs about the Russian nation, church and people. They also communicate what he thought was the answer to all his questions. Tolstoy believed humans were supposed to live a simple lite and take care of their families. Tolstoy thought this would satisfy him and bring him happiness.

    Leo Tolstoy is still a very respected writer today. His faith and writings have influenced many people. Tolstoy's search for the meaning of life is something everyone can understand. His teachings still interest people all over the world.

    Artificial intelligence (AI) technology may soon be a useful tool for doctors. It may help them better understand and treat diseases like breast cancer in ways that were never before possible.

    Rishi Rawat teaches AI at the University of Southern California's (USC) Clinical Science Center in Los Angeles. He is part of a team of scientists who are researching how AI and machine learning can more easily recognize cancerous growths in the breast. Rawat provides information about cancer cells to a computer. He says this data helps the machine learn." You can put the data into computers and they will learn the patterns and the pattern recognition is important to making decisions."

    David Agus is another USC researcher. He says machines are not going to take the place of doctors. "Computers will not treat patients, but they will help make certain decisions and look for things that the human brain can't recognize by itself. Once a confirmed cancerous growth is removed, doctors still have to treat the patient to reduce the risk of cancer returning. The form of treatment depends on the kind of cancer."

    Currently, researchers take a thin piece of tissue, put it on a small piece of glass and add color to better see the cells. That process could take days or even longer. Scientists say artificial intelligence can do something better than just count cells. Through machine learning, it can recognize complex patterns, or structures, and learn how the cells are organized.

    The hope is that machines will soon be able to make a quick identification of cancer that is free of human mistakes. "All of a sudden, we have the computing power to really do it in real time. We couldn't have done this, we didn't have the computing power to do this several years ago, but now it's all changed." Agus adds that the process could be done for almost no cost in the developing world. He says that having a large amount of information about patients is important for a machine to effectively do its job in medicine.

    The University of Southern California researchers are now only studying breast cancer. But doctors predict artificial intelligence will one day make a difference in all forms of cancer.

    There are excellent reasons for anyone to seek out the optimistic. Optimists experience better health outcomes, live longer and are more satisfied with their relationships. Optimism enables people to hold on in the face of difficulty, while pessimism leaves them depressed and even expecting failure.

    I want that hopeful, optimistic outlook for my children. But many times we may feel pessimistic. The result of negativity makes me worry that my kids' future will be uncertain. Fortunately, research suggests ways to help our children grow up with an optimistic attitude and maintain a happier outlook ourselves.

    Humanity has improved by many measures, but that success has become the water in which we swim, and like fish, we take the water for granted. While we fail to notice the positive, our brains naturally emphasize on the negative. With practice, we can help our brains to give the good stuff equal weight. Dr. Hanson's advice: when you hear a great story or achieve something in your own life, deliberately rest your mind on that experience and stay with it. Sink into that feeling as it sinks into you. Describe what you're doing to your kids, and encourage them to dwell on their joys and pleasures as well.

    Following the "big scary" news can leave us feeling helpless. Find something in your area that makes you feel hopeful, and make it a part of your family life. Researchers found that when people with a pessimistic outlook use positive language to describe situations they find upsetting, their feelings about the situation become more positive. That's something we can try at home.

    Raising optimistic kids is hard because it demands that parents abandon the pessimistic perspective that's the easiest response to pessimistic times. Put your energy into making sure you and your family are a part of the world around you. That might mean simply joining and being part of local clubs that feed our natural human need for connection (not of the digital kind).