When did you last see a polar bear(北极熊）? On a trip to a zoo, perhaps? If you had attended a winter activity in New York a few years ago, you would have seen a whole polar bear club. These "Polar Bears" are people who meet frequently in the winter to swim in freezing cold water. That day, the air temperature was 3℃,and the water temperature was a little higher. The members of the Polar Bear Club at Coney Island, New York are usually about the age of 60.Members must satisfy two requirements. First, they must get along well with everyone else in the group; this is very important because there are so many different kinds of people in the club. Polar Bears must also agree to swim outdoors at least twice a month from November through February.

    Doctors don't agree about the medical effects of cold-winter swimming. Some are worried about the dangers of a condition in which the body's temperature drops so low that finally the heart stops. Other doctors, however, point out that there is more danger of a heart attack during summer swimming because the difference between the air temperature and water temperature is much greater in summer than in winter.

    The Polar Bears themselves are satisfied with the benefits of cold-water swimming. They say that their favorite form of exercise is very good for the circulatory system(循环系统）because it forces the blood to move fast to keep the body warm. Cold-water swimmers usually turn bright red after a few minutes in the water. A person who turns blue probably has a very poor circulatory system and should not try cold-water swimming.

    The main benefits of cold-water swimming are probably mental. The Polar Bears love to swim all year round; they find it fun and relaxing. As one 70-year-old woman says," When I go into water, I pour my troubles into the ocean and let them float away."

    A new study of 8,000 young people in the Journal of Health and Social Behavior shows that although love can make adults live healthily and happily, it is a bad thing for young people. Puppy love(早恋)may bring stress for young people and can lead to depression. The study shows that girls become more depressed than boys, and younger girls are the worst of all.

    The possible reason for the connection between love and higher risk of depression for girls is “loss of self”. According to the study，even though boys would say “lose themselves in a romantic relationship”, this “loss of self” is much more likely to lead to depression when it happens to girls. Young girls who have romantic relationships usually like hiding their feelings and opinions. They won't tell that to their parents.

    Dr Marianm Kaufman，an expert on young people problems, says 15% to 20% young people will have depression during their growing. Trying romance often causes the depression. She advises kids not to jump into romance too early. During growing up, it is important for young people to build b friendships and a b sense of self. She also suggests the parents should encourage their kids to keep close to their friends, attend more interesting school activities and spend enough time with family.

    Parents should watch for signs of depression—eating or mood changes—and if they see signs from their daughters or sons, they need to give help. The good news is that the connection between romance and depression seems to become weak with age. Love will always make us feel young, but only maturity(成熟)gives us a chance to avoid its bad side effects.

    E-Sports, short for electronic sports, is one of the growing industries in the world, with prizes totaling around $25 million up for grabs in some tournaments. E-Sports are professional multiplayer video game competitions. Any video game with a strong competitive element is considered e-Sports. The competition models itself after traditional professional sports in several ways: it uses corresponding tournament formats, involves player contracts, and is governed by regulations. The athletes who compete in e-Sports competitions are gamers．

    The history of e-Sports dates back to 1972 when some Stanford University students competed in the Intergalactic Space War Olympics for the opportunity to win a one-year subscription to the Rolling Stone Magazine. E-Sports pretty much continued on the rather quiet path until the 80s when competitions like the Space Invaders Championship shot them to the spotlight. 2002 marked the beginning of a new era for the sport and laid the foundation for what e-Sports would become thanks to the release of the Xbox live, which brought online play to consoles. Halo Ⅱ became the first game to be shown on national television for Major League Gaming in 2004, paving the way for e-Sports to become a global phenomenon.

    Today, e-Sports are growing at a rapid pace thanks to advance in technology and the arrival of streaming services like Twitch which have exposed video game competitions to a new audience due to their extensive reach.

    To understand how much impact Twitch has made, data from gaming analyst group Newzoo show that e-Sports global audience increased 43 percent from 204 million to 292 million between 2014 and 2016. Interestingly, this coincides (一致) with Amazon's acquisition of Twitch in 2014 and its effort to make the competition a spectator sport.

    Spending money on time-saving services reduces stress and boosts(增进）happiness, according to a new research, but shockingly, few of us do it.

    Whillans, a professor at HBS said, "Buying time helps to protect us from the stress in our lives caused by time pressure, and the feeling that we don't have enough minutes in the day to complete our tasks."

    The effect was clearest in the Canadian experiment, in which 60 working adults were given $40 to spend in two different ways. One weekend, they were told to spend the money on a material purchase—a gift for themselves. The next weekend, they were instructed to spend the $40 on anything that saved them time, from paying the neighbor ' s kid to run errands (跑腿）to taking an Uber instead of a bus.

    〇n the day they made the time-saving purchase, they felt happier, in a better mood, and lower feelings of time stress than on the day they bought a material purchase," said Whillans.

    The biggest surprise to the researchers was how few people would spend money on time-saving services. When they asked 98 working adults how they would spend a "windfall" of $40, only two percent named a purchase that would save them time.

    "One reason," said Whillans, is that we're very bad at remembering how much we hate doing certain tasks once the suffering has passed. That makes us less likely to take active steps to avoid that overburdened feeling in the future. "But another possible cause is good old-fashioned guilt." If you feel guilty about getting someone to clean your house for you, then you might get less happiness from outsourcing (夕卜包）that task," said Whillans, "or you might just be less likely to spend your money in that way."

    When a laptop or smartphone battery starts losing its power, the only options are to buy an expensive replacement, or just keep it plugged in all the time. But a woman Mya Le Thai may have found the answer to this problem.

    Thai was frustrated that the batteries for her wireless devices degraded(降级)over time, until they failed to charge fully. She did not like having to keep her laptop connected to an electrical outlet to keep it powered on. So, she decided to do something about that problem. At first, she and her team at UC Irvine thought about inventing a new battery. But as they experimented, Thai discovered something that might permit lithium—ion(锂离子)batteries to last forever.

    Lithium-ion batteries power most wireless devices. Over time, the batteries lose the ability to hold a charge. Most of these batteries have a life span of about 7,000 charging cycles before they die. One of the reasons lithium—ion batteries degrade is their use of nanowires to carry electricity. Nanowires are extremely thin. A human hair is thousands of times thicker, for example. Nanowires are extremely efficient carriers of electricity, which makes them useful in batteries.

    But, Thai had a theory—the nanowires might last longer if covered with a gel(凝胶). She and her team tested this theory. "It was a long process and a lot of work, "Thai said. The team tried many coverings for the wires. PMMA, a type of plastic, was one of them. The nanowires were coated with PMMA and cycled through charges 200, 000 times. The PMMA-coated nanowires showed no evidence of damage. The results suggest that batteries could last forever, without losing charging ability.

    Thai hopes to continue her research to understand why this gel works so well and to see if any other gel could create better results and she is enjoying the publicity about her discovery. She said she never expected her research to get media coverage. "It's kind of cool," she said. "I'm really glad people are showing interest in my work and not just in the work itself, but also in technology and energy."

A casual walk along the Beijing Central Axis, connecting the Drum Tower and the impressive Forbidden City — this was Zhao's first city-walking journey in the spring of last year. Since then, the 21-year-old student from Beijing Foreign Studies University has remained a city-walk fan, believing it to be the best way to "rediscover a city". 

"I visited Beijing before the start of my college life here, and it was a typical package tour during which going to scenic spots and taking photos was a big thing. The crowded tourist attractions gave me the impression that Beijing was a noisy place," Zhao said. 

With the increasing variety of travel choices, traditional group tours no longer satisfy people who are looking for a more personal and different travel experience and hoping to explore every part of the city in a more immersive （沉浸式的） way. 

Compared with tightly scheduled routes （路线） and picture-taking tours, city-walking focuses on free, casual and spontaneous （自发的） experiences. The trending city-walk culture, which encourages experiencing urban life with no transportation means except one's legs and feet, has also made splashes on various social media platforms. 

On the video-sharing app Douyin, the Chinese version of Tik-Tok, a recent video about citywalk routes in Guangzhou, Guangdong province, has gained more than 171,000 likes, with 72,000 viewers of all ages adding the video to their favorites. According to a report from lifestyle-sharing platform Xiaohongshu, in the first half of this year, searches about city-walks increased 30-fold from the previous year. "The route offers a glimpse （瞥见） into the culture and landscape in different historical stages, as well as its beautiful natural scenery," it said. 

Following his experience in Beijing, Zhao has also explored Wuhan in Hubei province, Hangzhou in Zhejiang province and other cities through city-walking tours. "City-walking is all about doing whatever you want in your own exploration of a city, and it is actually the kind of slow-paced, low-carbon lifestyle that I relate to so much," he said.