Leonardo da Vinci, one of the greatest thinkers in the world, began his career as an artist. Very little is known about Leonardo's early life. He was born in 1452 in the town of Vinci. As a boy, Leonardo showed a great interest in drawing, sculpting and observing nature.

    However, because Leonardo was born to parents who were not married to each other, he was barred from some studies and professions. He trained as an artist after moving to Florence with his father in the 1460s. It was an exciting time to be in Florence, one of the cultural capitals of Europe. Leonardo trained with one of the city's very successful artists, Andrea del Verrocchio. He was a painter, sculptor and gold worker. Verrocchio told his students that they needed to understand the body's bones and muscles when drawing people.

    Leonardo took the teacher's advice very seriously. He spent several periods of his life studying the human body by taking apart and examining dead bodies. While training as an artist, Leonardo also learned about and improved on relatively new painting methods at the time. One was the use of perspective(透视) to show depth. A method called “sfumato” helped to create a cloudy effect to suggest distance. “Chiaroscuro” is a method using light and shade as a painterly effect.

    Leonardo's first known portrait now hangs in the National Gallery in Washington, D. C. He made this painting of a young woman named Ginevra de' Benci around 1474. The woman has a pale face with dark hair. In the distance, Leonardo painted the Italian countryside.

    He soon received attention for his extraordinary artistic skills. Around 1475 he was asked to draw an angel in Verrocchio's painting “Baptism of Christ.” One story says that when Verrocchio saw Leonardo's addition to the painting, he was so amazed by his student's skill that he said he would never paint again.

    Whether you are young or young at heart, it is never too late to change, or take in some new and better practices into your daily life. Here are some wise lessons that I wish I knew when I was younger.

    I used to be worried about what others thought of me. Finally, I changed. Remember that if you're wasting too much time looking for respect(尊重) from others, then you will not have time to finish all you desire(期望).Everyone has an opinion, but in fact others' opinions about you are based more on their history and perceptions(观念) than anything you're actually doing. So depend on your own assessment(评估) of you rather than others'.

    Enjoy every moment of today. Don't wait to do or enjoy anything. Don't tell yourself you will do it tomorrow. If it is important to you, then do it today. Pay attention to what is happening now, the task at hand and all the choices you make today, big and small. Our future is set by what we decide and do today.

    What happened yesterday is over. You can not change it. So let it go. Don't waste your energy considering anger or unhappiness. It only stops you from moving forward in life.

    Look for the good in people. Celebrate the happy moments, big and small. Search for the chances for growth. Give helpful encouragement rather than unwanted criticism (批评). Be helpful whenever possible.

    In a word, life is serious but you can still be delighted and hopeful. Otherwise, what's the point?

    AlphaGo is a computer program that plays the board game Go.

    In March, 2016, the pride of humankind was crushed (粉碎) by a computer. Google's AlphaGo defeated the South Korean grandmaster (围棋大师) Lee Sedol four games to one, as the world looked on with shock and awe (敬畏). Artificial intelligence (AI, 人工智能) had suddenly reached a new and unexpected height.

    But as smart as AlphaGo is, it's no longer the best Go “player” in the world. Google's artificial intelligence group, DeepMind, has created the next generation of its Go-playing program, called AlphaGo Zero. The new AI program is unique in the way it learned to play Go. Instead of learning from thousands of human matches, as its predecessor (前任) did, AlphaGo Zero mastered Go in just two days without any human knowledge of the game and defeated AlphaGo by day three, reported The Guardian. It then went on to defeat AlphaGo 100 games to zero.

    To learn how to play Go, AlphaGo Zero played millions of matches against itself using only the basic rules of the game to rapidly create its own knowledge of it. Like the previous version, it used “reinforcement (增强) learning to become its own teacher,” according to DeepMind's website.

    “It's more powerful than previous approaches,” David Silver, AlphaGo's lead researcher, told The Guardian, “because by not using human data, or human expertise in any fashion, we've removed the constraints (约束) of human knowledge and it is able to create knowledge itself.”

    AlphaGo Zero's approach to self-learning is a significant advancement in AI that could be applied to help solve some of the world's biggest problems, according to a recent research report published in the journal Nature. For example, DeepMind co-founder Demis Hassabis argues that AlphaGo Zero could probably find cures for a number of serious diseases within weeks, according to The Telegraph. Indeed, the AI is now being used to study protein folding, which is connected to diseases such as Parkinson's and Alzheimer's.

    So now that AI has exceeded (超过) the bounds of human knowledge, perhaps the question is not about what AI can learn from humans, but what humans can learn from AI. We can only wait and see.

The young boy saw me, or rather, he saw the car and quickly ran up to me, eager to sell his bunches of bananas and bags of peanuts. Though he appeared to be about twelve, he seemed to have already known the bitterness of life. "Bananas 300 naira. Peanuts 200 naira." He said in a low voice. I bargained him down to 200 for the fruit and nuts. When he agreed, I handed him a 500 naira bill. He didn't have change. So I told him not to worry. He said thanks and smiled a row of perfect teeth.

    When, two weeks later, I saw the boy again, I was more aware of my position in a society where it's not that uncommon to see a little boy who should be in school standing on the corner selling fruit in the burning sun. My parents had raised me to be aware of the advantage we had been afforded and the responsibility it brought to us.

I pulled over and rolled down my window. He had a bunch of bananas and a bag of peanuts ready. I waved them away. "What's up?" asked him. "I…I don't have money to buy books for school." I reached into my pocket and handed him two fresh 500 naira bills. "Will this help?" I asked. He looked around nervously before taking the money. One thousand naira was a lot of money to someone whose family probably made about 5,000 naira or less each year. "Thank you, sir." he said. "Thank you very much!"

    When driving home, I wondered if my little friend actually used the money for schoolbooks. What if he's a cheat? And then I wondered why I did it. Did I do it to make myself feel better? Was I using him? I didn't know his name or the least bit about him, nor did I think to ask.

    Over the next six months, I was busy working in a news agency in northern Nigeria. Sometime after I returned, I went out for a drive. When I was about to pull over, the boy suddenly appeared by my window with a big smile ready on his face.

"Oh, gosh! Long time."

"Are you in school now?" I asked.

    He nodded.

"That's good," I said. A silence fell as we looked at each other, and then I realized what he wanted. "Here," I held out a 500 naira bill. "Take this." He shook his head and stepped back as if hurt. "What's wrong?" I asked. "It's a gift."

He shook his head again and brought his hand from behind his back. His face shone with sweat. He dropped a bunch of bananas and a bag of peanuts in the front seat before he said, "I've been waiting to give these to you."

    The loud continuous noise of the cars or the sound of a plane can force its way into the deepest forest, yet it's not only humans that ere bothered by the noise.

    Bioacoustician Bernie Krause has been studying the effect of noise pollution on wildlife, and has come across some interesting behaviors, especially among animals that communicate by vocalization（发声）, like humans. Birds use sound to communicate, but in noisy places, these animals have to shout over the natural noise to be heard.

    Krause mentions a study of nightingales to clarify what he means. The birds responded to traffic noise by singing louder and louder until they actually went beyond noise pollution standards in the city. To belt out (sing loudly) their songs, they increased their lung pressure fivefold, but scientists state that this is not dangerous for the birds themselves.

    Studies show that sudden noise can cause certain birds to leave their nests, exposing the young to their enemies. One study also showed that songbirds that nested close to busy motorways were much less productive than those that nested farther away. Mammals（哺乳动物）too are affected. A recent study showed that nursing caribou responded to plane noise by not producing enough milk to feed their young.

    In some cases noise pollution can actually help some animals while harming others. Toads（蟾蜍）and frogs are known to vocalize in synchrony（同步；同步方式）so that no predator (their enemies) can zero in on them. Krause found that when planes flew overhead and disturbed the toad's song, they lost their synchronicity, and it took them 45 minutes to get it back again. That gave their natural enemies plenty of time to find and catch individual toads by sound.

    According to Kruse, “Not only will noise pollution bother wildlife, but it won't help our lives either.”

    As the days get shorter and the chilly weather rolls in, we all want to curl up in a blanket and hibernate until spring rolls around. But making time to get outside in the sun, even when it's cold out, could have bigger mood benefits than you might realize.

    While the link between sunshine and mental health is nothing new, new research from Brigham Young University (BYU) has shown that the association may be even stronger than previously realized. It finds that sunlight exposure is by far the greatest weather-related factor determining mental health outcomes. In other words: more sunshine, more happiness.

    For the study, a psychologist, a physicist and a statistician from BYU teamed up to compare daily environmental data from the university's Physics and Astronomy Weather Station with emotional health data archived by day for 16,452 adult therapy patients who were being treated at the BYU Counseling and Psychological Services Center.

    Exposure to sunlight is a significant factor in seasonal affective disorder. Research has shown that the brain produces more of the feel-good neurotransmitter serotonin on sunny days than it does on darker days. What's more, lack of sunlight is linked with lower vitamin D levels, which in turn has been correlated with depression and low energy.

    If you're getting enough sun, your emotions should remain relatively stable, the researchers found. But as the amount of sunlight in the day is reduced, levels of emotional pain can soar. Other weather variables including temperature, pollution and rain were not found to have an impact on mental health.

    “We were surprised that many of the weather and pollution variables we included in the study were not significantly correlated with clients' scores on the distress measure once we had accounted for suntime," Dr. Mark Beecher, a professor of psychology at the university and the study's lead author, told The Huffington Post. “People tend to associate rainy days, pollution, and other meteorological phenomena with sadness or depression, but we did not find that.”