【推荐3】As heat waves continue to ravage the planet, air conditioners are becoming more and more common. However, these "active" cooling devices are posing problems because the electricity consumption which most people are concerned about and the release of ozone-damaging chemicals worsen the greenhouse gas effect, resulting in the creation of heat islands and further thermal pollution. Therefore, "passive" cooling, which doesn't have such effects, has attracted considerable attention from both scientists and ordinary people in recent years.

In a recent study, a team of researchers from China and US presented an eco-friendly, low-cost coating to keep buildings cooler while consuming zero electricity. Infrared radiation-based passive cooling has been investigated since 2014, but challenges, mainly the expensive and unsustainable design, have greatly limited their large-scale and widespread application. Besides, the imbalance in cooling ability of these coatings during the day and night tends to lead to great day-night temperature differences as more heat is lost than gained at night.

The solution therefore requires a "smart" mechanism that can both enhance daytime cooling and minimize nighttime heat loss. To do this, the researchers created a new smart coating comprised of conventional building materials, including titanium dioxide nanoparticles, fluorescent microparticles, and glass microspheres that were engineered to reflect most of the sun-light. Specifically, the titanium dioxide particles effectively reflect sunlight through light scattering（撒播）while the fluorescent particles increase the amount of reflection by changing the absorbed sunlight into fluorescence emissions, which drive more heat away from the building. Meanwhile, the glass microspheres re-send mid-infrared broadband radiation, allowing not only heat loss, but allowing heat exchange to take place between the building and the sky.

The coating was tested on a model concrete building. Through this efficient heat ex-change with the sky, daytime cooling was strengthened while nighttime cooling was reduced. The building's inside temperature was always maintained at around 26 ℃, even when the out-side temperature varied from 24 ℃ to 37 ℃ during the day. We believe this new coating will make it to commercialization soon, enabling a sustainable, passive cooling technology that could help to fight climate change and the global energy crisis.

【推荐1】This Monday, the nation will start to celebrate Presidents’ Day, just seven days before George Washington’s birthday. Everyone agrees that day is a holiday, but is it just to celebrate George Washington’s Birthday? What about Abraham Lincoln? Some government offices call it Presidents’ Day. Others say the holiday is officially Washington’s Birthday. Confused yet?

George Washington was elected the country’s first President on April 30, 1789. Soon after, Americans began publicly celebrating his birthday. Presidential historians say the actual date of George Washington’s birth is February 11, 1732. But a change in the calendar system 20 years later shifted all dates，making Washington’s birthday February 22, which is now well accepted. In 1879, Congress made Washington’s birthday an official federal holiday. It was the first federal holiday to celebrate an individual’s birthday. In 1968, Congress passed the Monday Holidays Act, which moved the holiday to the third Monday in February. The new law did not change the holiday’s name. It was still called Washington’s Birthday, even though some lawmakers wanted to call it Presidents’ Day to include Abraham Lincoln, whose actual birthday is February 12.

Many people argue that the holiday should celebrate all past Presidents. They feel Lincoln should be honored for his role in preserving the nation during the Civil War and helping to free slaves. Others feel the holiday should only honor Washington, the country’s first President. They say shifting the focus away from Washington would mean future generations of kids would not know about the Father of Our Country.

Laws have been introduced in Congress over the years to require use of the term ＂George Washington’s Birthday.＂but none of those laws have been passed. Meanwhile, many state governments and school districts now use the term ＂Presidents’ Day.＂Many stoles also use it to promote holiday sales.

Should the holiday honor Washington, Washington and Lincoln, or all past Presidents? Write to emailbag@timeforkids.com and tell us what you think.

【推荐2】In general, the riches of the natural world aren’t spread evenly across the globe. Places like the tropical (热带的) Andes in South America are simply packed with unique species, many of which can’t be found in any other places. Until recently, the main explanation for the biological riches concentrated in places like the Amazon Basin was that such places must be engines of biodiversity (生物多样性), with new species evolving at a faster rate than other parts of the world. But now, new research on bird evolution may turn that assumption on its head, instead supporting the idea that areas with fewer species actually tend to produce new species faster.

The researchers say these biodiversity “coldspots” are generally found in environments featuring freezing, dry and unstable conditions. Though the researchers found these locations with few bird species tend to produce new ones at high rates, they fail to accumulate many species because the unstable conditions frequently make the new life forms die out.

The more well­known “hotspots”, by contrast, have accumulated their large numbers of species by being warm, hospitable and relatively stable. Indeed, the researchers found that the countless bird species that call the Amazon home tend to be older in evolutionary terms. “New species do form in places like the Amazon, just not as frequently as in the dry grasslands in the Andes,” says Elizabeth, an evolutionary biologist at the University of Tennessee.

The researchers managed to collect 1,940 samples representing 1,287 of the 1,306 bird species from South America. Their analysis showed that the best predictor of whether an area would produce new species at a high rate was how many species lived there, rather than climate or geographic features like mountains. Species­rich areas tended to produce new species more slowly.

“Maybe bad environments generate new species more frequently because there’s less competition and more available opportunities for new species,” says Gustavo Bravo, a lead researcher.

The study’s findings add new urgency to protect ecosystems that may look barren, but may actually be nature’s hothouses for the evolution of new species.

【推荐3】A man paralyzed (瘫痪的) from the neck down has gained the ability to type words with his brain about as fast as the average smartphone user, a new study says.

This “mindwriting” was done through a science-fiction sounding brain-computer interface (BCI)) (接口) that picked up neural signals and fed them into an algorithm (算法) which translated them into letters. The secret to the success, and why this particular BCI was able to produce words at such a faster rate than other BCIs in the past, was that it tracked the brain signals of the patient, known as T5, as he imagined writing them down with a pen — a skill which remains in our motor skill system for years after paralysis.

“With this BCI, our study participant achieved typing speeds of 90 characters per minute,” wrote the study group, whose paper can be read in Nature. “To our knowledge, these typing speeds exceed (超过) those reported for any other BCI, and are comparable to typical smart phone typing speeds of individuals in the age group of our participant.” The study had conducted other trials with different BCIs before, in which they used eye-monitoring equipment, but found it required tremendous attention and focus from the user.

The new BCI isn’t yet developed enough to be called a model, meaning it will likely be years before more paralysis victims can regain their ability to communicate. However, this also means the room for improvement is much higher, explained one scientist, speaking with CNN.

【推荐1】Dan studied the tracks on the ground. For the third night in a row, the adult bear had returned. Was she here because she was just looking for an easy meal? Or was she here because of the baby bear locked in the pen? If that was the reason, what did she want with the cub?

Dan thought about the cub. He knew there was a lot the cub could learn from an adult bear. He did not want to disturb or interfere with the bears getting to know each other. But the cub had been brought in injured. As the cub’s guardian, Dan had a responsibility to make sure that the cub was safe. Perhaps he had been hurt by this very bear. On the other hand, what if the adult were friendly? She could teach the cub things he had to learn if he were to live in the wilderness. Dan decided it was worth taking a chance. He would let the adult bear near the cub. But he would be ready for trouble, if this turned out to be a mistake.

That night, Dan waited in the shadows near the pen. In his hand was a big flashlight. If the adult bear tried to hurt the cub, he would try to scare her off with the light. If that did not work, he had a loud horn with him. He thought that the sudden noise from the horn would drive her away.

Dan did not have to wait very long. Soon there was a rustling in the woods. Then the adult proclaimed her presence with a low growl and emerged from behind a tree. She was quick in movement and healthy. Dan hoped she would scare easily.

As soon as the cub heard her a frightening low noise, he became active and started toward the fence in an awkward run. When the two bears met at the fence, the adult stood and put her front paws against it. The cub tried to do the same, but tottered and fell forward. The adult bear snorted. Dan was not sure what the snort meant. Then the cub stuck his nose through the fence in a friendly greeting. How would the adult respond? Dan’s heart raced. He raised the flashlight and the horn, ready to act.

The adult leaned forward and gently rubbed her nose against the cub. Dan lowered the flashlight. Everything was going to be fine.

【推荐2】Stories are shared in many ways. They are described in books and magazines. They are read around the campfire at night. They are randomly distributed from stand-alone booths. But what else?

To revive literature in the era of fast news and smartphone addiction, Short Edition, a French publisher of short-form literature, has set up more than 30 story dispensers (分发机) in the USA in the past years to deliver fiction at the push of a button at restaurants, universities and government offices.

Francis Ford Coppola, the film director and winemaker, liked the idea so much that he invested in the company and placed a dispenser at his Cafe Zoetrope in San Francisco. Last month, public libraries in some other cities announced they would be setting them up, too. There is one on the campus at Penn State. A few can be found in downtown West Palm Beach, Fla. And Short Edition plans to announce more, including at the Los Angeles International Airport.

“Everything old is new again,” said Andrew Nurkin, director of the Free Library of Philadelphia, which is one of the libraries that set up the dispensers. “We want people to be easily exposed to literature. We want to advance literacy among children and inspire their creativity.”

Here’s how a dispenser works. It has three buttons on top indicating choices for stories that can be read in one minute, three minutes or five minutes. When a button is pushed, a short story is printed.

The stories are free. They are chosen from a computer category of more than 100,000 original submissions by writers whose works have been evaluated by Short Edition’s judges, and transmitted over a mobile network. Offerings can be tailored to specific interests, like children’s fiction or romance. Short Edition gets stories for its category by holding writing contests.

Short Edition set up its first booth in 2016 and has 150 machines worldwide. “The idea is to make people happy,” said Kristan Leroy, director of Short Edition. “There is too much unhappiness today.”

【推荐3】Linda Evans was my best friend — like the sister I never had. We did everything together: taking piano lessons, going to the movies, swimming, and horseback riding.

When I was 13, my family moved away. Linda and I kept in touch through letters, and we saw each other on special time — like my wedding(婚礼) and Linda’s. Soon we were busy with children and moving to new homes, and we wrote less often. One day a card that I sent came back, stamped “Address Unknown.” I had no idea how to find Linda.

Over the years, I missed Linda very much. I wanted to share the happiness of my children and then grandchildren with her. And I needed to share my sadness when my brother and then my mother died. There was an empty place in my heart that only a friend like Linda could fill.

One day I was reading a newspaper when I noticed a photo of a young woman who looked very much like Linda and whose last name was Wagmans — Linda’s married name. “There must be thousands of Wagmans,” I thought, but I still wrote to her.

She called as soon as she got my letter. “Mrs. Tobin!” she said excitedly, “Linda Evans Wagmans is my mother.” Minutes later I heard a voice that I knew very much, even after 40 years, then we laughed and cried and caught up on each other’s lives. Now the empty place in my heart is filled. And there’s one thing that Linda and I know for sure: We won’t lose each other again.

【推荐1】Imagine arriving at the airport…passing through security…finally boarding your flight and taking off…only to land a few hours later—right back where you started. No. Your plane didn't have a mechanical issue. You actually bought a plane ticket to nowhere.   It's a new kind of air travel that's become popular during the COVID-19 pandemic.

A growing number of airlines-including Qantas in Australia and All Nippon Airways in Japan—offer flights that take off and touch down at the same airport-without landing anywhere in between. Recently, Qantas introduced its first seven-hour scenic flight scheduled for Oct. 10 that featured views of the Great Barrier Reef, Sydney Harbor and the Uluru monolith. Tickets—which cost between 560 dollars and just over 2,700 dollars—were sold out in 10 minutes, according to the airline. The airline industry—the travel industry overall—has just been damaged by the pandemic. The International Air Transport Association predicts the airline industry as a whole will lose 84 billion dollars this year and almost 16 billion dollars in 2021 because of the pandemic. So this new kind of air travel offers airlines an opportunity to make some money and also keep staff working.

However, environmental groups say these "flights to nowhere" should not be the answer for cash-short airlines. Mark Carter, spokesman for Flight Free Australia（an environment group）argues, "Too many of us are unaware of flying's contribution to the climate crisis. And the passengers on Qantas' ‘flights to nowhere’ will increase their annual carbon release as they fly over the Great Barrier Reef because warming is causing repeated mass bleaching（白化）events before the Reef has time to recover.”

【推荐2】Shortly after the war，my brother and I were invited to spend a few days with an uncle who had just returned from abroad. He had rented a cottage in the country，although he rarely spent much time there. We understood the reason for this after our arrival: the cottage had no comfortable furniture（家具）in it；many of the windows were broken and the roof leaked（渗漏），making the whole house terrible.

On our first evening，we sat around the fire after supper listening to the stories which our uncle had to tell of his many adventures in distant countries. I was so tired after the long train journey that I would have preferred to go to bed；but I could not stand missing any of my uncle's exciting stories.

He was just in the middle of describing a rather terrifying experience he had once had when there was a loud crash from the bedroom above，the one where my brother and I were going to sleep.

"It sounds as if the roof has fallen in！"cried out my uncle，with a loud laugh.

When we got to the top of the stairs and opened the bedroom door，we could see nothing at first because of the thick clouds of dust which filled the room. When the dust began to clear，a strange sight met our eyes. A large part of the ceiling had fallen down，falling right onto the pillow（枕头）on my bed.

I was glad that I had stayed up late to listen to my uncle's stories，otherwise I should certainly have been seriously injured，perhaps killed.

That night we all slept on the floor in the sitting room downstairs，not wishing to risk our lives by sleeping under a roof which might at any moment fall down on our heads. We left for London the very next morning and my uncle gave up his cottage in the country. This was not the kind of adventure he cared for either！

【推荐3】It is no secret that physical activity is necessary to a person’s well-being. Because children are continuously developing physically and emotionally, they are especially affected by the benefits of activity. Former First Lady Michelle Obama’s Let’s Move initiative reports that nearly one-third of US children are overweight or obese, and that “schools are a key setting for kids to get their 60 minutes of play with moderate activity, given the significant portion(部分) of time they spend there.”

Physical education programs in schools directly benefit students’ physical health. Regular exercise promotes muscles and bone development. In addition to participating in physical activity, students in P.E. learn the fundamentals of a healthful lifestyle, the building blocks upon which they can develop into healthy, knowledgeable adults.

Though the lack of attention on P.E. is often justified as an opportunity to spend more time in the classroom, studies show that physical activity contributes to improved academic performance. Regular activity during the school day is strongly associated with higher concentration levels. A statewide policy in North Carolina requires that children from kindergarten to eighth grade participate in 30 minutes of physical activity each day.

Activities in P.E. help children develop healthful social interactions. From a young age, children learn cooperation through group activities and form a positive sense of identity as part of a team. Such group activities are continually important as children grow older. The International Platform on Sport and Development states that sport has been used as a practical tool to engage young people in their communities through volunteering, resulting in higher levels of leadership and community engagement among young people.

The benefits of P.E. to a child’s mental health are both complex and comprehensive. Improved physical health, academics and social interactions all contribute to good mental health. Physical activity sets the stage for a good night’s sleep, provides more energy to participate in hobbies and interact with others.