When I was watching a sports event yesterday, I met with an amazing sight. It was not a gold medal, or a world record broken, but a show of pure courage and determination.

    The event was swimming. I watched a man dive off the blocks and knew right away that something was wrong. I'm not an expert swimmer, but I can tell a good dive from a poor one, and this was not exactly medal quality. When he resurfaced, it was evident that the man was not out for gold — his arms were waving in an attempt at freestyle.

    I heard the crowd begin to laugh at this poor man who was clearly having a hard time. Finally he made his turn to start back. It was pitiful. He made a few desperate strokes (划水) and you could tell he was worn out. But in those few awkward strokes, the crowd changed. No longer were they laughing, but beginning to cheer. Some even began to stand and yell things like, "Come on, you can do it!" He did. The crowd went wild.

    Just a short year ago, he had never even swum, let alone race. His country had been invited to take part in the event. Even though he recorded the slowest time, this man gave more heart than any of the other competitors—a man that gave his all, knowing that he had no chance but to compete because of the spirit of the games.

    Easter (复活节) is still a great day for worship (崇拜), randy in baskets and running around the yard finding eggs, but every year it gets quite a bit worse for bunnies (兔子).

    And no, not because the kids like to pull their ears. The culprit is climate change, and some researchers found that rising temperatures arc having harmful effects on at least five species of rabbit in the US.

    Take the Lower Keys March rabbit, for instance. An endangered species that lives in the Lower Florida Keys, this species of cottontail is a great swimmer—it lives on the islands!—but it is already severely affected by development and now by rising levels. According to the Center for Biological Diversity, an ocean level rise of only 0.6 meters will send these guys jumping to higher ground and a 0.9-meter rise would wipe out their habitat (栖息地) completely.

    The snowshoe hare, on the other hand, has a color issue. Most of these rabbits change their fur color from white in the wintertime to brown in the summer, each designed to give them better cover from  predators (捕食者). As the number of days with snow decreases all across the country, however, more and more bunnies arc being left in white fur during brown dirt days of both fall and spring, making them an easier mark for predators. Researchers know that the color change is controlled by the number of hours of sunlight, but whether the rabbit will be able to adapt quick enough to survive is a big question. The National Wildlife Federation has reported that hunters have noticed their numbers are already markedly down.

    American pikas or rock rabbits, a relative of rabbits and hares, might be the firs' of these species to go extinct due to climate change. About 7-8 inches long, pikas live high in the cool, damp mountains west of the Rocky Mountains. As global temperatures rise, they would naturally migrate (迁徙) to higher ground - but they already occupy (占据) the mountaintops. They can't go any higher. The National Wildlife Federation reports that they might not be able to stand the new temperatures as their habitat beats up.

    The volcano rabbit has the same problem. These rabbits live on the slopes of volcanoes in Mexico, and recent studies have shown that the lower range of their habitat has already shifted upward about 700 meters, but there are not suitable plants for them to move higher, so they are stuck in the middle. Scientists are concerned about their populations.

    Native to the US, pygmy rabbits weigh less than 1 pound and live in the American West. They are believed to be the smallest rabbits in the world. Their habitats have been destroyed by development. Several populations, such as the Columbia Basin pygmy, almost went extinct and were saved by zoo breeding programs. Pygmy rabbits also rely on winter cover by digging tunnels through the snow to escape predators, but lesser snowfall is leaving them exposed.

    All of this gives new meaning to dressing up in a giant bunny costume (服装) this Easter.

    Taxi-booking app Uber agreed to sell its business in China to Didi Chuxing. The two firms had been fierce competitors, but Didi Chuxing had controlled the Chinese market with an 87% share.

    Uber China launched in 2014, but it had failed to make any profit for a long time. Cheng Wei, founder and chief executive of Didi Chuxing, said the two companies had learned a great deal from each other over the past two years in China. He added that the deal would set the mobile transportation industry on a healthier path of growth at a higher level. As part of the deal, Mr. Cheng would join the board of Uber, while Uber chief executive Travis Kalanick would also join Didi's board.

    Uber's China business would own its separate branding while US-based Uber Technologies would hold about 17.5% in the combined company. Didi Chuxing is backed by Chinese Internet giants Tencent and Alibaba.

    Uber had been struggling to break into the Chinese market despite having Chinese search engine Baidu as an investor. Last February, the company admitted it was losing more than $1 billion a year in China. “Funding their Chinese dreams was becoming too expensive for Uber,” Duncan Clark, chairman of Beijing-based consultancy BDA, told the BBC. Travis Kalanick said, “As a businessman, I've learned that being successful is about listening to your head as well as following your heart.”

    The fierce competition had led both companies to spend much more on their journeys. The combination is likely to see fewer such subsidies（补贴）. “One thing to watch carefully is how quickly consumers feel the impact as subsidies are withdrawn.” Mr. Clark added.

    The deal with Didi Chuxing came just days after China had agreed to provide a legal framework for taxi-ordering apps. Both Uber and Didi welcomed the decision. The new rules took effect last November and could, among other things, forbid such platforms to operate below cost.

    Have you ever been afraid to talk back when you were treated unfairly? Have you ever bought something just because the salesman talked you into it? Many people are afraid to speak out for their rights. Dr Robert Albert, author of Stand Up, Speak Out, and Talk Back thinks it's because their self-respect is low.

    But Albert and other scientists are doing something to help people help themselves. They offer "assertiveness training" courses A. T. for short. In the A.T. Course people learn that they have a right to be themselves. They learn to speak out and feel good about doing so. They learn to help themselves without hurting other people.

In one way, learning to speak out is to get rid of fear. A group taking an A. T. Course will help the shy person to lose his fear. But A. T.uses an even stronger motive— he needs to share. The shy person speaks out in the group because he wants to tell how he feels. Whether or not you speak up for yourself depends on your self-respect. If someone you face is more "important" than you, you may feel less of a person. You start to doubt your answers to problems. You can get to feel good about yourself. And once you do you can learn to speak out.

    Like infectious diseases, ideas in the academic world are epidemic (传染的). But why some travel far and wide while equally good ones has been a mystery? Now a team of computer scientists has used an epidemiological model to simulate (模仿) how ideas move from one academic institution to another. The model showed that ideas originating at famous institutions caused bigger "epidemics" than equally good ideas from less famous places, explains Allison Morgan, a computer scientist at the University of Colorado Boulder.

    "This implies that where an idea is born shapes how far it spreads," says senior author Aaron Clauset.

    Not only is this unfair— "it reveals a big weakness in how we're doing science," says Simon DeDeo, a professor of social and decision sciences at Carnegie Mellon university, who was not involved in the study. "There are many highly trained people with good ideas who do not end up at top institutions. They are producing good ideas, and we know those ideas are getting lost," DeDeo says. "Our science, our scholarships, is not as good because of this."

    The Colorado researchers first looked at how five big ideas in computer science spread to new institutions. They found that hiring a new faculty member accounted for this movement a little more than a third of the time--and in 81 percent of those cases, transmissions took place from higher – to lower-prestige (声望) universities. Then the team simulated the spread of ideas using an infectious disease model and found that the size of an idea "epidemic" depended on the prestige of the originating institution.

    The researchers' model suggests that there "may be a number of quite good ideas that originate in the middle of the pack, in terms of universities." Clauset says. There is a lot of good work coming out of less famous places, he says: "You can learn a huge amount from it, and you can learn things that other people don't know because they're not even paying attention."

    A science teacher from rural Kenya who gives away most of his salary to help poorer students has been awarded the world's best teacher and $ 1 million, beating 10,000 nominations from 179 countries. Peter Tabichi, 36, a maths and physics teacher at Keriko secondary school in Pwani Village, has won the Varkey Foundation Global Teacher Prize 2019.

    Tabichi gives away 80% of his income to help the poorest students at the poorly-equipped and overcrowded school who could not otherwise afford uniforms and books. More than 90% of his students are from poor families and almost a third are orphans or have only one parent. Drug abuse, teenage pregnancies, leaving off their studies, young marriages and suicide are common. Students have to walk 7 km along roads that can become impassable in the rainy season to reach the school and the area can be affected by drought and starvation.

    Despite only having one computer, a poor Internet connection and a student-teacher ratio of 58:1, Tabichi started a "talent nurturing club" and expanded the school's science club, helping students design research projects of such quality that many now qualify for national competitions.

    His students have taken part in international science competitions and won an award from the Royal Society of Chemistry after using local plant life to generate electricity. Tabichi and four colleagues also give struggling students one-to-one tuition in maths and science, visiting students' homes and meeting their families to identify the challenges they face.

    Accepting the prize, Tabichi said Africa's young people would no longer be held back by low expectations." Africa will produce scientists, engineers and entrepreneurs whose names will be one day famous in every corner of the world." he said.