【推荐2】Every living thing has DNA that can be used to identify it. They leave bits of DNA behind them wherever they go. DNA left behind like this is called “environmental” DNA, or eDNA. Scientists can use it to tell what kinds of animals are in a certain place.

Testing eDNA isn’t a new idea. Most of the time, scientists used to look for eDNA in water. Now, there are two teams of scientists who have come up with a new way of identifying animals in an area by testing eDNA in the air.

Both teams chose to test in zoos because there were rare animals not naturally found in the area. One team collected samples from different locations at Denmark’s Copenhagen Zoo, and the other team did it at Hamerton Zoo Park in the UK.

Basically, both teams used vacuums and fans to collect tiny bits of eDNA in the air. After collecting samples, they went back to the laboratory and compared their samples with examples of DNA from different animals. Therefore, the scientists were able to identify many different animals at the zoos.

Both teams have tracked different animals, even endangered ones without interfering with them in this new way. They are so excited about their new way that they combine their results of the test and publish a paper together in order to invite more scientists to join them.

However, it’s still unknown that whether this new way will work out fine or not in the wild nature. If scientists know where the wild animals live, they can do a better job of protecting them.

So the next step is to figure out how to take this new method into nature.

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【推荐1】Acting as an art form has changed a great deal over the centuries. It’s no longer just about entertaining an audience in a stylised way to depict (刻画) characters and events that everyone is familiar with. Nowadays, acting has moved into a world of hyper realism. Audiences often expect to be challenged by a performance, and acting asks sometimes difficult questions about the world around us.

Given this change in emphasis, what kind of toll (损害) might acting take on somebody’s well-being? The idea that there is a psychological price to pay for good acting is nothing new, yet there is surprisingly little scientific research that examines the issue. Many scientists have been unwilling to examine the relationship in depth. This is changing, however, with academics now starting to investigate it further.

Actors often agree that performing can come with risks. Deborah Margolin, an award-winning actor, found the line between her stage self and her real personality started to blur (变模糊) the deeper into the character she went. She felt a real emotional impact especially when she played difficult or unpleasant roles. Margolin explains, “It was depressing...my character would cry, and I would cry.” She recalls the impact on her fellow actors: “Everybody backed away from me. These were lovely people—I loved them dearly—but my character was unattractive and somehow, so was I.”

These feelings are easy to understand, and would seem to be a natural outcome of acting styles such as “method acting”, which encourages actors to use their real-life experiences to fuel a role. There are some, however, who disagree. Actor Sanford Meisner felt that an actor’s most important tool is their imagination and that psychology has no place in performance. In fact, many performers mix these different methods and keep in touch with family to reconnect with the person beyond their character.

There’s no doubt that walking a tightrope between personalities can be a difficult task, however. As drama student Naomi Lorrain explains, “It can be hard. Offstage, you have to remember that it’s unreal and onstage you have to forget...”

【推荐1】Some young people win attention because of their good looks or their singing ability. A much smaller number gain fame because they have done something important and worthwhile with their abilities. Rishab Jain is among the latter. In 2018, 13-year-old Rishab developed a way to use AI technology to help pancreatic(胰腺的) cancer patients and won the 3M Young Scientist Challenge, a nationwide middle-school science competition, and its $25,000 prize.

In the last stage of the contest, Rishab competed against nine other finalists at the 3M Innovation Center(创新中心) in St. Paul, Minnesota. Leading up to the big meet, each finalist had partnered with a scientist to further develop their inventions.

Rishab explains what led him to create his invention. First, a family friend died of cancer. Then Rishab learned about how deadly pancreatic cancer is, and that its low survival rate is due to how difficult it is to treat. "I'm also into programming, so I was learning about AI technology. I decided to try to solve a real-world problem using it."

His winnings have been put in further research and in his nonprofit Samyak Science Society, which helps poor children enter the STEM (science, technology, engineering and math) education. Rishab is also raising awareness about pancreatic cancer. These efforts make him quite different from teenagers of his age. Considering becoming a biomedical engineer or a doctor一or both, he has also put some money aside to further his own learning. Almost certainly the doors of higher education will open wide to him before he even knocks.

That's an outstanding outlook for one so young. Rashib is committed to helping very sick people in need. He is also providing teenagers of his age with a much-needed model of what kinds of things youth can achieve.

【推荐2】This may look like a mud-covered swamp (沼泽) creature, but it’s actually a kid enjoying Mud Day, an annual summer tradition at Nankin Mills Park in Wayne County, Michigan. Each July, thousands of people play in a mud-filled hole measuring 21 by 46 metres.

“It’s been one of the county’s most successful events,” says Beth Hughes, a representative of Wayne County. “The kids just love it.”

It might look like a lot of fun to dive into a huge pool of mud. But is this dirty activity safe? In general, mud is mostly harmless, says Steven Davis, a doctor in San Antonio, Texas. But mud can contain things like bacteria that can cause infections. If you’re planning on diving into the mud anytime soon, try to avoid getting it in your mouth, eyes, or nose, warns Davis. Also, wash off really well when you are finished. And if you have an open cut, the safest bet is to just stay out of the mud.

In some cases, covering your body with mud can actually be a good thing. Some mud, like that from the Dead Sea in the Middle East, is rich in elements (元素) that could be beneficial for the skin, such as calcium, magnesium and zinc. It’s also why some spas (休闲健身中心) offer mud baths as a beauty treatment.

“One of the reasons why people lie in the Dead Sea or cover themselves in mud is that the minerals in it may reduce swelling,” says Davis. A layer of mud may also act as a seal(密封) on the skin to trap in moisture (水分). Besides, the warmth of a mud bath just makes people feel good.

【推荐3】Cold, snowy weather has arrived in many places. That means young people are enjoying building snowmen, going snowboarding and having snowball fights.

But in one small American city, children can’t play with snow to the fullest. The town of Severance, north of Denver, gets about 100 centimeters of snowfall a year. For almost 100 years, city rules have said it is forbidden to throw or shoot stones or missiles at people, animals, buildings, trees or vehicles. Snowballs were considered to be part of the town’s definitions of “missiles”.

Kyle Rietkerk works for the town of Severance. He said children cannot believe it and that town leaders have for years told the children, “You have the power. You can change the law.” But no one has tried—until now. Nine-year-old Dane Best lives in Severance with his parents and little brother. He has made it his goal to get the snowball fight ban overturned (推翻). Dane said he believes the law is “outdated”. “I want to be able to throw a snowball without getting in trouble, and I really expect to hit my brother with a snowball,” he said.

Dane’s mother, Brooke Best, told a newspaper that her son found out it was illegal to throw snowballs within town limits about a month and a half ago. Since then, he has been talking about how to change that. Dane wrote letters with his classmates in support of overturning the ban. And on Monday, he spoke about the problem at a Severance town meeting. Leaders listened as Dane presented his arguments and all voted for him. Then, Dane threw the first legal snowball in the parking lot of the Town Hall.

Dane said, “My parents and I have researched other Severance rules, including one that defines pets only as cats and dogs. And I have guinea pigs, which appears to be illegal in Severance, too. But I believe that will be different soon.”