【推荐2】We think of winter as cold and flu season，but the cold temperatures have powerful biological upsides too.

Boosts your brain

    1     .Studies have found that people perform some cognitive（认知的）tasks like making decisions better when the temperature is cooler. Research has also shown that people are less willing to handle complex tasks in the summer than in the winter.

Burns calories（卡路里）

When it's cold，your body works harder to keep your core temperature，which is typically. about 98.6 degrees. "Our bodies use a considerable amount of energy to keep us warm and to dampen the air we breathe when we're out in the cold，"explains Stacy Tucker，an expert from Kansas City.     2       . A recent study showed that participants burned 34 percent more calories when they hiked in 14-to 23-degree temperatures than they did hiking on 50-degree days.

Activates healthy fat

We know accumulating too much ordinary fat or "white fat" can endanger our health. But adults also have small amounts of beneficial "brown fat" that can quicken their metabolism（新陈代谢）and bum more calories     3     .

Encourages better sleep

Your body's core temperature drops when you're trying to sleep.     4     ，but it's much faster in winter，says Tucker. Plus，with darker mornings，you naturally sleep later.

    5    

Yes，you might get more colds during the winter. However，studies have shown that the immune system can be activated by colder temperatures，which improves our ability to fight infections，explains Tucker. That said，the flu virus becomes strong in cold，dry air，and time spent indoors increases your chance of infection. To reduce risk，get your annual flu shot，wash your hands frequently，and go outside.

【推荐3】It’s normal for teens to want to stay connected with friends and social circle, but what about that happening in the middle of the night? The Journal of Youth Studies recently published new research showing that one in five teens from 12 to 15 regularly wake to spend all night on social media (社会媒体). Not surprisingly, the research also showed that these social night owls were three times more likely than others to feel tired at school and that girls were more likely than boys to be called to office.

The blue light produced by cell phones and computers makes the brain to stay awake, so it's easy to see why a teen might be up all night. A study in Psychological Science showed the same brain reaction: when teens saw large numbers of “likes” on their posts, they stayed awake with excitement as if they had eaten chocolates or won money. Besides not catching up on sleep and interrupting their sleep cycle, teens may never fully enter deep sleep that may be responsible for brain development and learning.

Considering about 72 percent of children from 6 to 17 sleep with some electronic media in their bedrooms, parents need to set rules sooner rather than later.

“Providing access (使用机会) to social media is a favor that children can earn and also lose,” Janie Feldman, an expert who treats sleep disorders (紊乱), reminds parents, “The bad effect is clear. So teens and parents should discuss and agree on its use, timing and access. When teenagers agree to the rules, it’s easier for parents to control how much time they use the phones or computers.”

【推荐3】Blood-Doping Champion

Blood doping (违规输血) to improve performance is forbidden in professional sports. Athletes can use this technique to fuel their muscles with more oxygen-carrying red blood cells—for example, by receiving a transfusion. But many animals dope naturally: sheep, fishes and horses can boost their blood’s capacity to carry oxygen by 16 to 74 percent in physically demanding situations. Now a study shows that an Antarctic fish called the bald notothen can increase its carrying capacity by more than 200 percent to pursue an active life in cold waters.

Like most fishes native to Antarctica, the bald notothen’s blood contains anti-freeze proteins that help it withstand extreme cold. But these proteins, along with red blood cells (RBCs), can make blood sticky and hard to circulate. Some Antarctic fishes adapt by removing RBCs altogether, absorbing oxygen directly from the water via skin as they passively await prey (猎物). Bald notothens, however, actively swim below surface ice to chase other active life when avoiding seals and penguins. For this behavior, “you need to supply more oxygen to the muscles,” says Michael Axelsson, a physiologist at the University of Gothenburg in Sweden and co-author of the new study.

The scientists compared RBC levels in samples collected from bald notothens relaxing in glass tanks with those in samples drawn from fish they “chased” using a plastic tube. RBC levels were at 9 percent in the resting animals but 27 percent in the exercised ones, showing a 207 percent increase in the latter’s blood oxygen carrying capacity. “No other fish we’ve seen can more than double their RBCs or drop their numbers to such a low level when resting,” Axelsson says. The fish’s spleen (脾) stores RBCs, and the researcher found that to release more into the bloodstream, the organ shrinks to weigh 41 percent less.

The enormous changes in RBC levels initially surprised Gerald Kooyman, a biologist at the Scripps Institution of Oceanography, who was not involved in the study. He notes, however, that these animals have fewer blood cells to begin with, so maintaining circulation with a tripled RBC count is less difficult. If a diving Weddell seal pushed its RBC levels from 40 to 90 percent, for instance, its blood would be dangerously hard to pump.

Yet bald notothens do face trade-offs for their ability. The scientists found blood pressure was 12 percent higher and the heart worked 30 percent harder in active individuals. Bald notothens can rest during quiet times, but when they need to use their abilities, Axelsson says, “these fish have to live with more RBCs because they need more oxygen.”

【推荐1】For centuries, people have kept large amounts of cash at home during difficult times. But during the coronavirus (冠状病毒) crisis, things are different. Metal coins and paper money can be a source of worry rather than hope.

The fear is that these objects, possibly touched by thousands of people, could provide a way for the coronavirus to spread. Public officials and health experts have said that the risk is small. Still, some businesses refuse to accept cash and some countries have suggested that their citizens should stop using it altogether.

Zachary Cohle is an economics professor at Quinnipiac University in Connecticut. “In many areas, cash was already beginning to disappear due to the increased risk of robbery, the ease of Internet ordering, and the ubiquity (无处不在) of cell phones,” he said. “Sweden, Finland, Norway, Canada and others have slowly reduced cash use to the point where using it in large amounts seems unusual. Britain and Australia are expected to become cashless countries. And in China, cash use has dropped as electronic payment services have increased over the past ten years.”

“Cash ist Fesch” is a common saying in Austria and southern Germany. The words mean cash is beautiful. But since the virus outbreak, shops that have remained open there, like grocery stores, have encouraged people to pay with cards. And Germany’s central bank said 43 percent of Germans recently paid for goods and services with a card. The Bank of Japan estimates that cash makes up 53 percent of household assets (家庭资产). But the threat of the coronavirus could move the country toward going cashless, said Hiroki Maruyama, head of the nonprofit Fintech Association of Japan. He added, “The culture is slowly changing.”

However, cash use is still common in places like West and Central Africa, where many are too poor to pay for the cost of banking services. Dorothy Harpool teaches at Wichita State University’s W. Frank Barton School of Business. Harpool thought some people would rethink their use of cash during the crisis, but she said the world would not be cashless until everyone and every country has a reliable   way to use the Internet.

【推荐1】Two graduates from Cambridge University in the United Kingdom found themselves about to graduate, yet with loans to pay off. The pair decided to begin a strange, year-long project to battle their debt.

The men, Ross Harper and Edward Moyse, set up the website BuyMyFace.com last October as a way to get rid of the £50,000 they shared as student loans. The idea behind the project was to earn money by selling their faces as advertising space every day for a year. Each day, they advertise a different business by painting the brand’s name or logo onto their faces and upload the pictures to the homepage of BuyMyFace.com, adding a link to the advertiser’s website and including a short piece of text about it. After they paint their faces and publish them on the website, Harper and Moyse go out to highly populated areas such as music festivals and theme parks to maximize their faces’ exposure. They hope more people will pay attention to the advertisements on their faces.

At this time, Harper and Moyse have advertised their faces for over four months without skipping a day and they’re more than halfway to their goal. Though they first started charging a minimum of about £1.60 per company, the prices have risen as their popularity increases. For advertising space during the rest of April, they range between £250 and £750. Terri L. Rittenburg, associate professor of marketing at the University of Wyoming, said that she had heard of people tattooing (纹身) logos on themselves before, but this idea is much better. According to her, at first the idea would be new and unusual and attract attention. People are interested in this particular style of advertisement and would like to try what they advertise. But she is unsure how long it would last.

At least for now, companies that have bought Harper and Moyse’s faces have written positive comments on the pair’s website. “We had a three percent increase in website traffic on the very day and for two days more afterwards,” said one of the companies.

【推荐2】Garbage sorting has become a hot issue around China, especially after Shanghai began carrying out a regulation on July 1.

Beijing, as a forerunner in environmental protection, has thus been expected to follow suit. The capital of the country has long been campaigning for sorting and recycling household waste, as part of its environmental drive for sustainable growth, local media reported.

The current regulation gives garbage sorting responsibilities to government departments, property management groups and other organizations. It also gives rules for companies, outlining how they’re responsible for waste collection, transportation and treatment. Only individuals are not subject to responsibilities.

The long-awaited revision will soon change the situation, “Taking out the trash without sorting it properly will be illegal,” said Sun Xinjun, director of the Beijing Commission of Urban Management. In Shanghai, violators are now fined up to 200 yuan ($30)for trash-sorting violations. The maximum fine in Beijing will not be less than that, he said.

The Beijing city government first set out to promote garbage sorting in 2009. Authorities have since called on citizens to sort their household waste into four types-recyclable waste, kitchen trash, dangerous waste and others-and leave it in a corresponding dustbin or trash can. Blue-colored dustbins signify items within are recyclable, green represents kitchen trash, red corresponds to dangerous materials and grey to other waste.

To promote the awareness of garbage sorting and expand the base of participants, authorities have employed workers to help residents on the spot. With intelligent devices, those who throw in recyclable waste at given sites will be rewarded with bonus points, which can be used to buy daily goods. At some communities, there are no color-coded dustbins. Instead, a scheduled garbage collection service is offered to help improve the environment. In other communities, workers offer a door-to-door service to collect recyclables or kitchen waste.

Beijing Environmental Sanitation Engineering Group has been promoting new garbage sorting facilities such as recycling cabinets and smart kitchen waste trash cans since 2016, Xinhua News Agency reported. Nearly 26,000 metric tons of household waste is generated across Beijing on a daily basis and 29 terminal garbage disposal facilities are working at full capacity. Nearly 9.3 million tons of household waste was processed in the city last year.

【推荐3】The number one thing you'll probably do is book your flight if you want to travel to another country. But in some countries, you won't be able to fly directly.

Vatican City, the smallest country in the world, as a 109-acre area in the middle of Rome, doesn't have its own airport, but visitors can easily get there via Italy's capital.

Similarly, San Marino, the fifth smallest country in the world, is also surrounded by Italian land. It has a population of a little more than 33,000 and sits just nine miles from Federico Fellini International Airport in Rimini, Italy.

The second-smallest country in the world is Monaco, with a population of more than 38, 500. To get there, you'll have to go through France's Nice Cote d' Azur Airport, which is just a 25-minute car ride away from Monaco. Perhaps that's why developers didn't bother creating anything like a short flight.

Interestingly enough, the third and fourth smallest countries, Nauru and Tuvalu have their own airports, but the fifth and sixth smallest don't We already mentioned San Marino, and to get to Liechtenstein, you'll have to go through Switzerland's St. Gallen-Altenrhein Airport, 24 miles away from the capital.

No such luck trying to fly into Andorra, which only requires a 25-mile drive to get from one end of the country to the other. Situated in a mountain range valley, Andorra has too much difficulty in building an airport runway. But for visitors there is no difficulty in going Andorra. Both Spain and France have access to Andorra. The closest way to Andorra's capital is Girona-Costa Brava Airport in Spain.