Imagine that you're looking at your company-issued smartphone and you notice an e-mail from Linkedln: “These companies are looking for candidates like you!” You aren't necessarily searching for a job, but you're always open to opportunities, so out of curiosity, you click on the link. A few minutes later your boss appears at your desk. “We've noticed that you're spending more time on Linkedln lately, so I wanted to talk with you about your career and whether you're happy here,” she says. Uh-oh.

     It's an awkward scene. Attrition (损耗) has always been expensive for companies, but in many industries the cost of losing good workers is rising, owing to tight labor markets. Thus companies are making greater efforts to predict which workers are at high risk of leaving ,so that managers can try to stop them. Methods range from electronic monitor to well-designed analyses of employees' social media lives.

     Some of this work may be a reason to let employees to quit. In general, people leave their jobs because they don't like their boss, don't see opportunities for promotion or growth, or are offered a higher pay; these reasons have held steady for years.

    New research conducted by CEB, a Washington-based technology company, looks not just at why workers quit but also at when. “We've learned that what really affects people is their sense of how they're doing compared with other people in their peer group, or with where they thought they would be at a certain point in life, says Brian Kropp, who heads CEB's HR practice. “We've learned to focus on moments that allow people to make these comparisons.”

Technology also provides clues about which star employees might be eyeing the exit. Companies can tell whether employees using work computers or phones are spending time on (or even just opening e-mails from) career websites, and research shows that more firms are paying attention to these things. Large companies have also begun searching for badge swipes (浏览痕迹)—- employees' use of an ID to enter and exit the building or the parking garage—to identify patterns that suggest a worker may be interviewing for a job.

    Today, we know that the role of vitamins and minerals goes way beyond the prevention of deficiency diseases (维生素缺乏症) to actually preventing cancer and heart disease, the most fearsome killers of our time. With this knowledge has come the widespread call for nutritional supplementation (营养补充) — and a confusing group of vitamin, mineral, and supplements lining the supermarket shelves.

    Far from contributing to better health, however, nutritional supplements threaten to turn a scientific breakthrough into a nutritional disaster.

    Promoters of vitamins and minerals — especially vitamins A, C, and E— would have consumers believe that the little vitamin pill in the bottle is all they need for good health. Take your vitamins in the morning, and you're covered. It's okay to eat fast foods for the rest of the day or skip meals to achieve today's fashionably skinny look. But vitamins and minerals are only one part of the nutritional puzzle. A diet rich in fiber (纤维) and balanced in carbohydrates and protein is essential for good health. You can't get these things from a nutritional supplement. The focus on vitamin and mineral supplements may actually be robbing us of the full nutrition we seek.

    And no supplement can compare to the quality of nutrition found in natural sources. For example, our bodies turn carotenes (胡萝卜素) from plant foods into vitamin A. Many supplements contain a single carotene, but natural sources are rich in many different carotenes. Many supplements contain a form of vitamin E that is made from chemicals, when natural vitamin E is more readily absorbed and used by the body. And science is still discovering the wealth of nutrients in foods.

    You'd be hard-pressed to find a supplement as nutritionally comprehensive and powerful as a balanced diet. Even if you could, you'd pay much more than if you got the same nutritional value from natural sources.

    But perhaps the greatest danger presented by nutritional supplements comes from the very real risks presented by self-medication. Anyone can walk into the market and buy as many different supplements as desired. The reported benefits of high dosages of certain nutrients have led some people to believe that the more the better. Many take several vitamin and mineral supplements without regard to possible consequences.

    Surprising new research suggests that vitamin C pills may speed up hardening of the arteries, the underlying cause of heart attacks. Researchers said their findings support the recommendations of health organizations, which urge people to avoid high doses of supplements and to get their nutrients from food instead.

    As appealing as they're made to sound, nutritional supplements are danger in disguise. If you're looking for good health, don't look on the supplement shelves of your supermarket. Look in the produce section instead.

    The Coolest Inventions

    An Oceans Vacuum(吸尘器)

    There's a collection of plastic trash in the middle of the Pacific Ocean. It's bigger than Texas and growing. The way to clean it up now is to catch it with nets. That is both costly and slow. Instead, the Ocean Cleanup Project proposes a 62-mile-long floating barrier that would use natural currents to trap trash. If next year's trials succeed, a full cleanup operation would aim to start in 2020. It could reduce the trash by 42% over 10 years.

    Easy-On Shoes

    In 2012, Matthew Walzer, a high school student with a disability, sent a note to Nike. “My dream is to go to college,” he wrote, “without having to worry about someone coming to tie my shoes every day.” Nike assigned a design team to the challenge. This year, they came out with their solution: the FlyEase. The basketball shoe can be fastened with one hand. A pair of Nike FlyEase shoes sells for $130.

    An Airport for Drones (无人机)

    As Amazon, Google, and others get ready for drone delivery service, there is one big question: What kinds of home bases will their drones have? Rwanda, in Africa, may have the answer. There, workers will soon start work on three “drone ports”. The goals is to make it easier to transport food, medical supplies, electronics, and other goods through the hilly countryside. Construction is set to be completed in 2020.

    Healthy, convenient and increasingly popular over the past few years, sushi has become as common a dish in the UK as in India or China. It's a popular lunch-choice for city-workers all over the country and you're never far from a restaurant or supermarket selling the traditional Japanese dish. But it turns out sushi may not be as healthy a choice as we thought — leading biologists have warned that it is in fact harming both the environment and our health.

    The UK sushi market is worth £69 million a year, but because we're eating so much of it, the tuna (金枪鱼) population in the oceans is dwindling. According to Professor Daniel Pauly and Dr Dirk Zeller, the leaders of British Columbia, Bluefin and yellowfin tuna populations have reached dangerous levels.

    Bluefin tuna is often served in high-end, excellent sushi restaurants, while yellowfin is more common in high-street sushi bars and supermarkets. Increasing global need means tuna populations are being overfished. Most of the UK's sushi comes from the Indian Ocean, but according to Professor Pauly we now only have 2-3 percent of what we had 200 years ago.

    Professor Pauly and Dr Zeller believe it is our love of healthy tuna that's causing the problems in our oceans. The fish is popular not just for its taste but for its health benefits. But while sushi has earned popularity for being low in calories and high in nutrients (营养物), we may have overestimated (高估) its health value.

    In advance of a lecture at the Zoological Society of London lately, Professor Pauly said he believes most high-street restaurants serve sushi that contains plastic microbeads (塑料微珠). “Microbeads are poison pills which take in all the pollutants and they are eaten by little fish which are then eaten by tuna.”

    So what should we eat instead? Dr Zeller and Professor Pauly are asking the public to step away from sushi and eat more fish like anchovies (凤尾鱼) — less attractive, but better for your health and the environment.

    Breathing dirty air comes at a high price. Air pollution lowers the average life spans (寿命) by a year worldwide and in more polluted parts of Asia and Africa, dirty air shortens lives up to twice that much. Scientists shared their new findings in Environmental Science & Technology Letters. The study used data gathered in 2016 as part of a project known as the Global Burden of Disease and was the first major country-by-country look at the connection between the length of life and what's known as fine PM.

    Air pollution has been linked to many health problems. Most earlier studies had looked at how tiny air pollutants affected rates of illness or death. Joshua Apte is an environmental scientist at the University of Texas at Austin. By looking at life expectancy (预期寿命), his team had hoped to make the threat easier to understand. PM2.5 is what scientists call tiny particles (颗粒) of pollution in the air. Higher levels of PM2.5 can cause health problems and cut months, if not years, from the average length of life. This analysis shows how pollution affects life expectancy in different parts of the world.

    The World Health Organization (WHO) recommends limiting PM2.5 to 10 micrograms per cubic meter of air. Apte's group calculated how holding pollution to this low level would help people. In countries with very dirty air, meeting this standard would lengthen people's lives. However, in countries whose air already meets this standard, the study shows no gain in life expectancy. In other words, meeting the WHO standard won't reduce health costs resulting from dirty air because even below 10 micrograms per cubic meter, pollution still causes serious risks. Meanwhile, the scientists compared how other threats including smoking and cancer shorten the length of life across the globe.

October 15th is Global Handwashing Day. Activities are planned in more than twenty countries to get millions of people in the developing world to wash their hands with soap.

Experts say people around the world wash their hands but very few use soap at so-called extremely important moments. These include after using the toilet, after cleaning a baby and before touching food.

Global Handwashing Day is the idea of the Public Private Partnership for handwashing with soap. The goal, they say, is to create a culture of handwashing with soap. The organizers say all soaps are equally effective at removing disease-causing germs. They say the correct way to wash is to wet your hands with a small amount of water and cover them with soap. Rub it into all areas, including under the fingernails.  Then, wash well under running water. Finally, dry your hands with a clean cloth.

The Partnership says soap is important because it increases the time that people spend washing. Soap also helps to break up the dirt that holds most of the germs.  And it usually leaves a pleasant smell, which increases the chances that people will wash again.

It also says that washing hands with soap before eating and after using the toilet could save more lives than any medicine. It could help reduce cases of diarrhea, which is the second leading cause of child deaths, killing more than one and a half million children a year, by almost half.