【推荐2】A multi-institutional team of researchers conducted the first study to evaluate how the duration of nightly sleep early in the semester affects first year college students’ end-of-semester grade point average (GPA), Using Fitbit sleep trackers, they found that students on average sleep 6.5 hours a night, but negative outcomes accumulate when students received less than six hours of sleep a night. The results are available in the Feb. 13 issue of the Proceedings of the National Academy of Sciences.

Sleep guidelines recommend teenagers get 8 to 10 hours of sleep every night. Many college students experience irregular and insufficient sleep.

David Creswell, the William S. Dietrich Ⅱ Professor in Psychology and Neuroscience at the Dietrich College of Humanities and Social Sciences, led a team of researchers to evaluate the relationship between sleep and GPA．“Animal studies have shown how critical sleep is for learning and memory,” said Creswell.“Here we show how this work translates to humans.The less nightly sleep a first year college student gets at the beginning of the school term predicts lower GPA at the end of the term. Lack of sleep may be hurting students’ ability to learn in their college classrooms.”

The study evaluated more than 600 first-year students across five studies at three universities. The students wore wrist Fitbit devices to monitor and record their sleep patterns. The researchers found that students in the study sleep on average 6.5 hours a night.More surprisingly, the researchers found that students who receive less than six hours of sleep experienced a pronounced decline in academic performance. In addition, each hour of sleep lost corresponded to a 0.07 decrease in end-of-term GPA．

“Once you start dipping (下降) below six hours, you are starting to accumulate massive sleep debt that can impair a student’s health and study habits, compromising the whole system,” said Creswell.“Most surprising to me was that no matter what we did to make the effect go away, it persisted.”

【推荐3】Some parents will buy any high-tech toy if they think it will help their child, but researchers said puzzles help children with math-related skills.

Psychologist Susan Levine, an expert on mathematics development in young children the University of Chicago, found children who play with puzzles between ages 2 and 4 later develop better spatial skills….

The researchers analyzed video recordings of 53 child-parent pairs during everyday activities at home and found children who play with puzzles between 26 and 46 months of age have better spatial skills when assessed at 54 months of age.

“The children who played with puzzles performed better than those who did not, on tasks that assessed their ability to rotate and translate shapes,” Levine said in a statement.

The parents were asked to interact with their children as they normally would, and about half of children in the study played with puzzles at one time. …

The findings were published in the journal Developmental Science.

【推荐1】Bitcoin and other so-called cryptocurrencies (加密货币)have been all over the news lately. Apparently, the idea of money that’s not tied to a specific bank—or a specific country—is appealing to many. But it’s worth remembering that the banking system that we now all live with is just that： A modern invention. Not so long ago, money was almost always created and used locally, and bartering was common. (In fact, it still is common among many online local networks, like the Buy Nothing Project.).

In the past, money’s makeup varied from place to place, depending on what was considered valuable there. So while some of the world’s first coins were made from a naturally occurring hybrid of gold and silver called electrum (银金矿)，objects other than coins have served as currency, including beads, ivory, livestock, and cowrie shells. In West Africa, bracelets of bronze or copper were used as cash, especially if the transaction was associated with the slave trade there. Throughout the colonial period, tobacco was used to replace coins or paper bills in Virginia, Maryland and North Carolina, even though it was used elsewhere in the colonies and extensively throughout Europe and the U. K.

Today, on an island in the Pacific, a specific type of shell still serves as currency—and some people there are even hoarding(贮存)it, just like Bitcoin moguls, convinced that one day, it will make them wealthy beyond imagination. On Malaita, the most-populated island that’s part of the Solomon Islands, shells are accepted at most places in exchange for goods.

”How much tuna(金枪鱼)you can get for your shells depends on their color and shape,“ Mary Bruno, a shop owner from the small town of Auki, on Malaita, told Vice. ”One strip of darker shells might get you about two cans of smaller tuna, but the red ones are worth more. For the red ones, one strip might get enough tuna to feed a big family for a long time.“

Just like a mint that creates coins, there’s only one place on the island where the shells, which are polished and strung together to form 3-foot-long ropes, are made. The strips of red, white, and black shells all come from Langa Langa Lagoon, where artificial islands were long-ago built by locals to escape from the island-dwelling cannibals. Once marooned(困住)out on their islands, locals needed a currency to use among themselves, and so the shell currency was born.

Using shells for money was common throughout the Pacific islands as late as the early 1900s, but Malaita is unique in that they are still used today. And just like cryptocurrencies, there are those who think the islanders are smart to invest in this type of money, which is reported to have risen in value over the last three decades. It might seem strange to hoard a bunch of processed, strung-together shells, but what is a pile of dollars? Just a specially printed piece of paper and hemp that we’ve assigned value to—and probably less durable over time than those shells.

【推荐2】Can a small group of drones (无人机) guarantee the safety and reliability of railways and, at the same time, help railway operators save billions of euros each year? That is the very likely future of applying today’s “eyes in the sky” technology to making sure that the millions of kilometres of rail tracks and infrastructure (基础设施) worldwide are safe for trains on a 24/7 basis.

Drones are already being used to examine high-tension electrical lines. They could do precisely the same thing to inspect railway lines and other vital aspects of rail infrastructure such as the correct position of railway tracks and switching points. The more regularly they can be inspected, the more railway safety, reliability and on-time performance will be improved. Costs would be cut and operations would be more efficient (高效) across the board.

That includes huge savings in maintenance costs and better protection of railway personnel safety. It is calculated that European railways alone spend approximately 20 billion euros a year on maintenance, including sending maintenance staff, often at night, to inspect and repair the rail infrastructure. That can be dangerous work that could be avoided with drones assisting the crews’ efforts.

By using the latest technologies, drones could also start providing higher-value services for railways, detecting faults in the rail or switches, before they can cause any safety problems. To perform these tasks, drones for rail don’t need to be flying overhead. Engineers are now working on a new concept: the rail drones of the future. They will be moving on the track ahead of the train, and programmed to run autonomously. Very small drones with advanced sensors and AI and travelling ahead of the train could guide it like a co-pilot. With their ability to see ahead, they could signal any problem, so that fast-moving trains would be able to react in time.

【推荐1】Sitting in the garden for my friend’s birthday. I felt a buzz (振动) in my pocket. My heart raced when I saw the email sender’s name. The email started off: “Dear Mr Green, thank you for your interest” and “the review process took longer than expected.” It ended with “We are sorry to inform you…” and my vision blurred (模糊). The position—measuring soil quality in the Sahara Desert as part of an undergraduate research programme — had felt like the answer I had spent years looking for.

I had put so much time and emotional energy into applying, and I thought the rejection meant the end of the road for my science career.

So I was shocked when, not long after the email, Professor Mary Devon, who was running the programme, invited me to observe the work being done in her lab. I jumped at the chance, and a few weeks later I was equally shocked—and overjoyed—when she invited me to talk with her about potential projects I could pursue in her lab. What she proposed didn’t seem as exciting as the original project I had applied to, but I was going to give it my all.

I found myself working with a robotics professor on techniques for collecting data from the desert remotely. That project, which I could complete from my sofa instead of in the burning heat of the desert, not only survived the lockdown but worked where traditional methods didn’t. In the end, I had a new scientific interest to pursue.

When I applied to graduate school, I found three programmes promising to allow me to follow my desired research direction. And I applied with the same anxious excitement as before. When I was rejected from one that had seemed like a perfect fit, it was undoubtedly difficult. But this time I had the perspective (视角) to keep it from sending me into panic. It helped that in the end I was accepted into one of the other programmes I was also excited about.

Rather than setting plans in stone, I’ve learned that sometimes I need to take the opportunities that are offered, even if they don’t sound perfect at the time, and make the most of them.

【推荐2】Turning soil, pulling weeds, and harvesting cabbage sound like tough work for middle and high school kids. And at first it is, says Abby Jaramillo, who with another teacher started Urban Sprouts, a school garden program at four low-income schools. The program aims to help students develop science skills, environmental awareness, and healthy lifestyles.

Jaramillo’s students live in neighborhoods where fresh food and green space are not easy to find and fast food restaurants outnumber grocery stores. “The kids literally come to school with bags of snacks and large bottles of soft drinks,” she says. “They come to us thinking vegetables are awful, dirt is awful, insects are awful.” Though some are initially scared of the insects and turned off by the dirt, most are eager to try something new.

Urban Sprouts’ classes, at two middle schools and two high schools, include hands-on experiments such as soil testing, flower-and-seed dissection, tastings of fresh or dried produce, and work in the garden. Several times a year, students cook the vegetables they grow, and they occasionally make salads for their entire schools.

Program evaluations show that kids eat more vegetables as a result of the classes. “We have students who say they went home and talked to their parents and now they’re eating differently,” Jaramillo says.

She adds that the program’s benefits go beyond nutrition. Some students get so interested in gardening that they bring home seeds to start their own vegetable gardens. Besides, working in the garden seems to have a calming effect on Jaramillo’s special education students, many of whom have emotional control issues. “They get outside,” she says, “and they feel successful.”

【推荐3】Like most of us, I try to be mindful of food that goes to waste. The arugula (芝麻菜)was to make a nice green salad, rounding out a roast chicken dinner. But I ended up working late. Then friends called with a dinner invitation. I stuck the chicken in the freezer. But as days passed, the arugula went bad. Even worse, I had unthinkingly bought way too much; I could have made six salads with what I threw out.

In a world where nearly 800 million people a year go hungry, “food waste goes against the moral grain,” as Elizabeth Royte writes in this month’s cover story. It’s jaw-dropping how much perfectly good food is thrown away — from “ugly” (but quite eatable) vegetables rejected by grocers to large amounts of uneaten dishes thrown into restaurant garbage cans.

Producing food that no one eats wastes the water, fuel, and other resources used to grow it. That makes food waste an environmental problem. In fact, Royte writes, “if food waste were a country, it would be the third largest producer of greenhouse gases in the world.”

If that’s hard to understand, let’s keep it as simple as the arugula at the back of my refrigerator. Mike Curtin sees my arugula story all the time — but for him, it’s more like 12 bones of donated strawberries nearing their last days. Curtin is CEO of DC Central Kitchen in Washington, D.C., which recovers food and turns it into healthy meals. Last year it recovered more than 807,500 pounds of food by taking donations and collecting blemished (有瑕疵的) produce that otherwise would have rotted in fields. And the strawberries? Volunteers will wash, cut, and freeze or dry them for use in meals down the road.

Such methods seem obvious, yet so often we just don’t think. “Everyone can play a part in reducing waste, whether by not purchasing more food than necessary in your weekly shopping or by asking restaurants to not include the side dish you won’t eat,” Curtin says.