1 . While it's not impossible for birds to fly in the rain, they usually choose not to. You may see birds fly for a few seconds in poor weather, but most of them prefer to stay put on rainy days.

Why does rain make it harder for birds to fly? You might imagine that moving through the air while being pelted by raindrops would be pretty unpleasant. However, it's not the rain itself that makes flying difficult. Instead, birds are influenced by the drop in the air pressure that comes with most rainstorms. When pressure drops, the air is less thick, which makes it harder for birds to fly. Moving through the sky in areas of low air pressure takes a lot of energy.

Most birds need to eat several times a day—rain or no rain. Luckily, most birds' feathers（羽毛）are highly waterproof（防水的）, protecting the skin beneath. Many birds can also make oil that they can spread over their feathers to further protect themselves from the rain. Most birds don't like rain. In fact, in a 2010 study, a team of researchers studied birds living in a Costa Rican rainforest. They found that the birds had higher levels of stress hormone（应激激素）on rainy days. That may not surprise you. After all, many animals feel stressed out during storms. Pet owners often find that rain and thunder make their animals nervous. Some animals are so strongly influenced by nature that they almost seem to forecast the future.

No one really knows how many birds die during a storm or series of storms. But the number is certainly higher than usual. They fly into trees or windows; they get lost over the ocean or a large lake; their food sources are made more difficult to get but, at the same time, they need more food to get warm. However, if rain continues for some time, birds will have to challenge the storm.

2 . Motion sickness is an uncomfortable feeling. The sickness it causes can strike people on an airplane, playing video games, or, commonly, when riding in a car. In a future where people may find themselves running around streets in self-driving vehicles, the problems could get worse.

We typically sense our physical position and movement in the world by relying on our eyes, the feeling we get in our body, and our inner ear. Motion sickness may develop when there's disagreement between what your eyes see and what your inner ear senses. If you're looking at your phone in a moving vehicle, your eyes see a stationary screen but your inner ear feels that you're moving. The result of that dissonance can cause sickness. The common-sense solution is to just stop looking at your phone, but some of the appeal of self-driving cars is that you could use the time to be productive or entertained by what's on a screen.

Researchers of a car-making company and a video game company have been studying ways to address these issues. And their solution uses an interesting medium: sound. The research had two goals: to explore if sound could help relieve motion sickness, and to help people trust self-driving cars more. They experimented with two different categories of sound: tips that tell passengers what's about to happen, and noises that alert passengers when the device has noticed something, like a pedestrian.

The most convincing experiment took place on a closed airport runway in Sweden, near Gothenburg, in August of last year. On that track, brave participants had to ride in the backseat of a car driven by a human and read from a tablet while the car navigated the course. With just 20 people, the study was small, but according to researchers, the presence of sound tips made people report that they felt less ill. Participants said the sounds helped prepare them physically, or adjust their bodies for what was about to happen.

4 . An international group of electronic music composers is taking beats from the dance club to jungles and forests and back, all to help save nature's greatest singers. A Guide to the Birdsong of Mexico, Central America and the Caribbean is a new album that includes the sounds of endangered birds. The album will come out next month, whose proceeds will go directly towards efforts to save birds.

The whole project was born out of this idea of trying to combine birdsong, electronic music and conservation. A Guide to the Birdsong of Mexico, Central America and the Caribbean was organized by activist, music producer, Robin Perkins. He invited artists from each of the endangered birds 'homelands to build their own songs around the birds’ songs. There are contributions from ten artists in eight different countries.

First single Black Catbird was created by The Garifuna Collective, from Belize. Al Obando, guitarist and producer of the group, always took in national parks and viewed birds when on the road with the band. “There are no trails, and there are no signs there to tell you about what you reseeing,” Obando says. “So we're trying to do something for the birds and nature tourism.”

Another musician who responded to Robin's call is Tamara Montenegro, an artist from Nicaragua. She was shocked to hear of the serious situation of the Guardabarranco after being approached: “This beautiful creature I grew up adoring also faced the influence of the systematic human activities”. In response, she created a song inspired by this bird and the challenges it faces to live naturally.

The new album is the second edition, following on from A Guide to the Birdsong of South America, produced by Robin in 2015. That first album has raised, to date, over $15,000 benefitting conservation projects in South America. As with the first album, all of the money from the sales of the new album will support specific organizations, including Birds Caribbean.

5 . Americans are now allowed to get a COVID-19 vaccine （疫苗）. But the process in America is not going as smoothly as some had hoped. Many people are still facing a wait for their first shot. Moreover, the vaccines aren't available to kids under 16 yet. That's because scientists have only tested if the vaccine works in adults.

The good news is that there are two companies, Moderna and Pfizer, making COVID-19 vaccines. They are now running clinical trials（临床实验）to test their vaccines in teens and kids. Volunteers are given a treatment plan and then evaluated after.

Clinical trials are designed with safety in mind and usually done in adults first. They work like this: volunteers get placed into one of two groups. One group receives the vaccine. The other group gets a placebo. This is a shot given in the same way as the vaccine but with no effect. Scientists can compare the effects of the real vaccine against the placebo to see if the vaccine works. Researchers want to know everything that a person experiences when they get the shot, so they can detect any harmful effects. If anything did happen, the trial would stop immediately.

Some teens are eager to volunteer because they want to help people. Maybe you're the right age to be part of a clinical trial for the COVID-19 vaccine. Why not volunteer For A Vaccine Trial? Interested kids should read about the trials because every trial has risks. They should talk to their doctor and weigh the benefits and risks. Every vaccine has rare side effects in a few patients.

If you want to participate in a trial, you can try to sign up online by just clicking here, clinicaltrials gov. which lists every clinical trial in the US, including COVID-19 vaccine trials.

6 . The over 48,000 orange trees that are distributed at all corners of Seville, Spain, not only fill the city's air with the pleasant smell of their flowers in spring, they also produce over 16, 500 tons of fruit every winter. Though that makes the city Europe's top orange-producing city, the fruit is too sour to be consumed fresh. While some of the produce is used to make orange juice, most of it ends up in Seville's landfills. However, that may change soon thanks to a creative idea to use the oranges to produce clean energy.

In the pilot program, juice from 38. 6 tons of oranges will be left to ferment (发酵)in an existing biogas facility. The juice is fructose (果糖)made up of very short carbon chains, and the energetic performance of these carbon chains during the fermentation process is particularly high. The gas released from the fermented liquid will be used to drive a generator to produce clean power. The officials estimate the test run will generate about 1,500 kWh of energy—enough to run a water purification plant. "It's not just about saving money. The oranges are a problem for the city, and we're producing added value from waste,^M said Benigno Lopez, the head of Emasesa's environmental department.

If successful, by 2023, the city hopes to recycle all the oranges and add the electricity generated back to its grid (电网). In trial runs, 1,000 kilos (2,200 pounds) of oranges produced 50 kWh of clean energy一enough to meet the daily electricity needs of five homes. The project team estimates that if all the fruit is recycled, it will produce enough energy to power as many as 73,000 residences.

The latest effort is among the many programs implemented in Spain to achieve the country's goal of switching its electricity system to renewable sources by 2050—and if everything goes according to plan, fully decarbonizing its economy shortly after that.

7 . It would be easy to believe that Mother’s Day was created by a greeting card company. After all, the day is celebrated with special sales and brunches, lots of presents and massive advertising campaigns. But the day was actually conceived more than a century ago by Anna Jarvis of West Virginia as a way of honoring the sacrifices mothers made for their children.

Jarvis’s mother, Ann Reeves Jarvis, helped start “Mothers’ Day Work Clubs,” teaching women how to care for their children. During the Civil War, she organized “Mothers’ Friendship Day,” where mothers of Union and Confederate soldiers met to try to promote harmony. The younger Jarvis Was inspired by all the things her mother had accomplished with her social work.

When Jarvis was young, she overheard her mother praying, “I hope and pray that someone, sometime, will find a memorial mother’s day honoring her for the matchless service she offers to humanity in every field of life.” When her mom died in 1905, Jarvis looked through all the sympathy cards she received. She underlined all the kind words that praised her mother, reading them over and over. The outpouring of kindness for her mother inspired her to create a day to honor all mothers.

The white carnation was her mother’s favorite flower, so it became the symbol for the day. She said it symbolized the truth, purity and charity of a mother’s love. Her idea of celebrating Mother’s Day was wearing a carnation while visiting your mother or maybe going to church together. Children were also encouraged to write letters to their mothers, sharing the depths of their appreciation.

The first official Mother’s Day events were held on May 10. 1908, at the church where her mother taught Sunday School in Grafton, West Virginia, and at the Wanamaker’s department store auditorium（礼堂）in Philadelphia. Jarvis didn’t attend the event in Grafton, but she sent 500 white carnations.

8 . People who play drums regularly for years differ from unmusical people in their brain structure and function. The results of a study by researchers from Bochum suggest that they have fewer, but thicker fibers in the main connecting tract between the brain hemispheres(半球). In addition, their motor brain areas are organized more efficiently. This is the conclusion drawn by a research team headed by Dr. Lara. It was published in the journal Brain and Behavior, online on 4 December 2019.

The researchers were interested in drummers because their movement control far surpasses that of untrained people. "Most people can only perform fine motor tasks with one hand and have problems playing different rhythms with both hands at the same time," explains Lara, "Drummers can do things that are impossible for untrained people."

The team intended to gain new insights into the organization of complex motor processes in the brain by identifying the changes in the brain caused by this training. The researchers tested 20 professional drummers who have played their instrument for an average of 17 years and currently practice for more than ten hours per week. They examined them using various MRI imaging techniques that provide insights into the structure and function of the brain. They then compared the data with measurements of 24 unmusical control subjects. Both groups had to play drums to test their abilities and were then examined in the MRI scanner.

Drummers presented clear differences in the front part of the corpus callosum(胼胝体)responsible for motor planning. The data indicated that the drummers had fewer but thicker fibers in this important connecting tract. This allows musicians to exchange information between the hemispheres more quickly than the controls.

Although drummers might be good at motor coordination, they are less active in motor tasks than that of control subjects. This phenomenon indicates that a more efficient brain organization in the areas leads to less activation in professionals.