【推荐1】Researchers at Brigham found about one in five teenagers now have some degree of hearing damage. The researchers did not say why hearing loss has risen, but other experts have strong suspicions. One likely culprit, they say, is MP3 players.

An MP3 player can be dangerous to hearing when its decibel level is turned up too high. High-decibel sounds can damage nerve endings, called hair cells. If a sound is loud enough, the damage can be permanent. A loud sound can shake the membrane (薄膜) on which the hair cells sit- “like an earthquake”. That shake can break or even uproot hair cells. When that happens, the hair cells are finished. Human ears cannot regrow hair cells. Therefore, when listening to an MP3 player, set a volume limit and avoid exposure to loud sounds.

On the other hand, the loudness of today’s music may not be totally under your control. Music companies have been purposely turning up the volume. It’s a trend called the fight for loudness.

Play a CD from the 1990s. Then play a newly released tune. Don’t touch the volume control. You’ll probably notice that the new CD sounds louder than the old one. Why? Sound engineers who create CDs are using dynamic range compression (压缩), a technology that makes the quiet parts of a song louder and the loud parts quieter. The overall effect of compression is a louder recording.

Many musicians and sound engineers aren’t pleased. They say that compression is driving down the quality of today, s music, making it sound flat and blaring. Gray Hobish, a sound engineer, explains that music should be a combination of loudness and softness. But music companies want to make music louder so it will stand out. That’s important in the competition among recording companies.

What about listeners? Many teenagers listen to music on the go in noisy places and through headphones, all of which reduce sound quality. So young listeners may not notice the poorer quality of modem recordings. “To their ears,” says Hobish, “the music sounds fine. And they are not aware of the hidden threat of the music they are enjoying.”

【推荐2】Symptoms of Dehydration (脱水)

You’re bad-tempered.

Researchers tested the mood and concentration of 25 women who drank healthy amounts of water one day, and then less the next two days. When slightly dehydrated, the women reported tiredness, bad temper, headaches and difficulty in focusing. In a separate test, men with mild dehydration also had trouble with mental tasks.     1     Scientists are still trying to figure out why.

You have a bad workout.

    2     It impacts how much you can push yourself. Even a 2 to 3 percent fluid loss affects your ability to get a good workout and more than 5 percent dehydration decreases exercise capacity by about 30 percent.

    3    

Driving while you’re dehydrated may be just as dangerous as getting behind the wheel drunk, in terms of how many mistakes you could make on the road. British researchers had participants take 2-hour drives using a simulator (模拟器). When they drank enough water, there were 47 driving errors.     4    

You feel dizzy when you stand up too fast.

Dehydration can make you feel dizzy or faint, or bring on that rush of light-headedness after you quickly get up from sitting or lying down.

The exact treatment for dehydration symptoms depends on age and how severely dehydrated someone is.     5     Most of the time, however, people use some over-the-counter solutions for kids, and adults can drink more water.

【推荐3】Queen Elizabeth II has led Great Britain through many tough times throughout her 68-year sovereignty (在位). But never, during her reign (统治), has an issue disrupted the British public as much as the current pandemic of coronavirus.

By April 6, the UK had had 47,806 confirmed cases. Among them, crucially, is British Prime Minister Boris Johnson, who has recently been hospitalized. With the country entering its peak infection period, the Queen made only her fifth televised address to the nation, aside from her annual Christmas broadcast, on April 5. The four other times she has made such an address have been to mark the Gulf War, the death of Princess Diana of Wales, the death of her mother and her Diamond Jubilee (登基六十周年纪念).

According to Jonny Dymond, the BBC’s royal correspondent (通讯记者), “The Palace could have played it safe, stressed unity and given thanks. But this [speech] was … designed to reassure (重拾信心) and inspire.”

In her pre-recorded statement, the Queen focused on the dedication (奉献) of her subjects. “We have seen heart-warming stories of people coming together to help others, be it through delivering food parcels and medicines, checking on neighbors, or converting (转变) businesses to help the relief effort.”

As well as thanking front line workers, she pushed a message of comfort and motivation. “Together, we are tackling this disease, and I want to reassure you that if we remain united and resolute, then we will overcome it.”

“We should take comfort that while we may have more still to endure, better days will return: we will be with our friends again; we will be with our families again; we will meet again.”

Following the speech, people throughout the country voiced their admiration for her moving words.

London Mayor Sadiq Khan praised the Queen’s focus on front line health-care workers, and councilor (议员) Oliver Cooper wrote, “Nobody could have rallied (振作) the country, the Commonwealth, and the world the way the Queen did.”

Some internet users even shared how they cried after the speech, while others wrote the words of the national anthem (国歌), God Save the Queen.

Indeed, the wisdom of Britain’s 93-year-old monarch (君主) offered hope to the millions of Britons under lockdown.

【推荐2】Western monarch butterflies (帝王蝶) spend their winters on the central California coast. A few months later, they produce young in the Central Valley and as far north and east as Idaho. But where they go in between remains an open question to biologists. Therefore, a group of biologists call on anyone who spots a monarch north of Santa Barbara this spring to get a quick shot and email them the photo with a date and a location.

“Something’s going on in early spring,” said Cheryl Schultz, a professor at Washington State University Vancouver. “Winter survival isn’t the problem in the short term, but they don’t know whether the monarchs are not making it producing places, not finding plants to feed themselves along the way,” she said.

The Western monarch population stood in the millions in the 1980s. In 2017, an annual count found 200,000 butterflies. In 2018, the number fell to about 30,000—a figure that held steady last year. The monarchs’ decline is part of a large trend among dozens of butterfly species in the West. What exactly caused the decline? Biologists attach it to a variety of reasons. Many chemicals are sprayed on the milkweed (乳草) monarchs will feed on. Climate change also plays a role in challenges facing monarchs. Yet, they’re not nearly as threatening as those leading to loss of their living room. Farms used to have rough borders that were grounds for the plants monarchs love and live in. However, newly applied practices pushed crops to the edge of fields.

“Butterflies often have good and bad years. We do think there’s potential to turn the situation around.” Dr. Schultz said. And she said she saw two reasons for that. First, the population decline seen in 2017—2018 wasn’t repeated last year. And second, she’s seen butterfly populations recover before.

【推荐2】Fahad Azad, an engineer in India, invented a robot named DuctBot. The toy-car sized DuctBot measured 23 centimeters in length, 19 centimeters in width and 9 centimeters in height and weighed just two kilograms.

The robot is designed to snake through dark, narrow air conditioning ducts(管道) and clean them. A pair of LEDs fitted on the robot light up the dirty scenery, so it can be captured(抓拍) by a camera.

In order to control it more easily, Mr. Azad chooses to fix DuctBot on wheels. The robot can clean off lots of dirt, as well as dead pigeons and insects. Keeping indoor air in good quality and monitoring carbon-dioxide levels in buildings with central air conditioning is a challenge. It is important in some places where clean air can mean a difference between life and death, such as hospitals. Dirty air has a bad influence on peopled health.

EPSCO, a Dubai-based company which specializes in improving indoor air quality, read about Mr. Azad’s invention in a national newspaper after he had won an international robotics competition. EPSCO had cleaning equipment, but it needed someone to get into those ducts to do the dirty, dangerous work. Across India, for example, the task still falls to children. They are small enough to go through those ducts.

In 2005, Mr. Azad who was still at university decided to do something about it. Six years later his own company, Robosoft Systems, has Bluestar, EPSCO and the Indian Navy, some leading air condition makers, as partners.

Mr. Azad and his ten employees are currently exploring robot designs to examine oil tanks or sewage(污水) pipes. Their biggest challenge is to make the robots user-friendly enough. Mr. Azad hopes that the robot could eventually be operated not by engineers but by workers. There will be lots of difficulties they need to overcome in the future.

【推荐3】It was in 2004 that I decided to build a garden at Charlton Manor Primary School. I’d seen the news reports about children lacking (缺乏) knowledge of where their food came from and felt that we as a society had been separated from food. The reason for this was clear to me: we were no longer educating our children about food in schools. I saw a garden as a chance for the children to learn in a real way. I also wanted to use it to cover topics: life cycles, flowering plants, creative writing and report writing. I believed that plenty of subjects could be well taught in a garden, while increasing pupils’ activity levels and encouraging teamwork.

With many teachers facing explanations from children such as “It wasn’t my fault” and “It wasn’t only me”, here was our chance to develop a sense of responsibility. It hasn’t all been plain sailing (一帆风顺) though. At the beginning, we tried hard to get some of the teachers on board, because of concerns that behavioural problems would worsen — because if they couldn’t trust the children in the classroom, wouldn’t they be worse outside? But once those teachers started making use of the garden there was recognisable behaviour change in those pupils. The children worked as a team and took responsibility for growing the plants.

We needed to think about funding (资金), too. I know other schools that have taken different routes to support such projects — finding parent and grandparent volunteers or someone with a knowledge of gardening who are ready to share their skills and support teachers. Community is a big thing for us. Products from the garden are sold in the school shop, run by the children on weekdays. We’ve also begun selling products, such as tomatoes, potatoes, eggs and honey to parents and others, and a local restaurant and Borough Market in central London, helping us to channel (引导) funds back into the garden.

The research of the Food Growing in Schools Taskforce makes clear the advantages of school gardens: learning, increased understanding of the natural environment. It has also shown that outdoor learning can add value to everyday experiences in the classroom. I’d agree. The garden has provided wonderful learning chances for the children. It has brought the community together.