Soaping up your hands may do more than just get rid of germs. It may wash away the inner confusion you feel right after being forced to make a choice between two appealing choices, according to a new study. The study builds on the past research into a phenomenon known as “the Macbeth effect” (麦克白效应）.

    It turns out that Shakespeare was really onto something when he imagined Lady Macbeth trying to clean her conscience by rubbing invisible bloodstains from her hands.

    A few years ago, scientists asked people to describe a past wrong act. If people were then given a chance to clean their hands, they later expressed less guilt than people who hadn't cleaned.

    This finding interested W. S. Lee, a researcher. “Anything from the past, any kind of negative emotional experiences, might be washed away,” says Lee.

    He decided to test hand washing's effect on one kind of bad feeling：the tension we feel after being forced to choose between two attractive choices, because picking one choice makes us feel that we've lost the other. People usually try to calm this inner conflict by later exaggerating (夸大）the positive aspects of their choice.

    He had students rank 10 different music CDs. Then he offered students two of the CDs and told them to select one as a gift. Some students then used liquid soap. Others only looked at the soap or sniffed (闻)it. “Actually, you do not need water and soap,” says Lee.

    Later, the students again had to rank all the music CDs. People who didn't wash their hands had the normal response — they scored their take-home CD higher, suggesting that they now saw it as an even more attractive one than before. But this wasn't true for the hand washers. They ranked the music about the same. “They feel no need at all to justify (证明…正确）the choice,” says Lee.

    But the effects of it just aren't clear. Schwarz says it's too soon to know whether people should head for a sink after making a tough choice. He says washing may help decision-makers by cleaning away mental disorder. But perhaps if they don't go through the usual post-decision process of justifying their choice, they might feel more sorrow in the long run.

    Optimism May Help People Live Longer

People who have an optimistic view on life are more likely to live longer, a US study said Wednesday.

    The study, published in the American Journal of Epidemiology, analyzed data from 2004 to 2012 from 70,000 women enrolled in the Nurses' Health Study, a long-running US study tracking women's health via surveys every two years.

    The researchers looked at participants' levels of optimism and other factors that might play a role in how optimism may affect mortality risk, such as race, high blood pressure, diet, and physical activity.

    It found the most optimistic women, or the top 25%, had a nearly 30 percent lower risk of dying from any of the diseases analyzed in the study compared with the least optimistic women, or the bottom 25%.

    The most optimistic women had a 16 percent lower risk of dying from cancer; 38 percent lower risk of dying from heart disease; 39 percent lower risk of dying from stroke; 38 percent lower risk of dying from respiratory disease; and 52 percent lower risk of dying from infection.

    Previous studies have linked optimism with reduced risk of early death from cardiovascular (心脑血管的) problems, but this was the first to find a link between optimism and reduced risk from other major causes.

    “While most medical and public health efforts today focus on reducing risk factors for diseases, evidence has been mounting that enhancing psychological resilience (弹性，复原力) may also make a difference,” said Eric Kim, research fellow at the Harvard T.H. Chan School of Public Health and co-lead author of the study.

    “Our new findings suggest that we should make efforts to boost optimism, which has been shown to be associated with healthier behaviors and healthier ways of coping with life challenges.”

    The study also found that healthy behaviors only partially explain the link between optimism and reduced mortality risk. One other possibility is that higher optimism directly affects our biological systems, Kim said.

    Co-lead author and postdoctoral research fellow Kaitlin Hagan said optimism can be varied with relatively uncomplicated and low-cost interventions (干预), even things as simple as having people write down and think about the best possible outcomes for various areas of their lives, such as careers or friendships.

    “Encouraging use of these interventions could be an innovative way to enhance health in the future,” Hagan said.

C

Plastic-Eating Worms

    Humans produce more than 300 million tons of plastic every year. Almost half of that winds up in landfills(垃圾填埋场), and up to 12 million tons pollute the oceans. So far there is no effective way to get rid of it, but a new study suggests an answer may lie in the stomachs of some hungry worms.

    Researchers in Spain and England recently found that the worms of the greater wax moth can break down polyethylene, which accounts for 40% of plastics. The team left 100 wax worms on a commercial polyethylene shopping bag for 12 hours, and the worms consumed and broke down about 92 milligrams, or almost 3% of it. To confirm that the worms' chewing alone was not responsible for the polyethylene breakdown, the researchers made some worms into paste(糊状物) and applied it to plastic films. 14 hours later the films had lost 13% of their mass — apparently broken down by enzymes (酶) from the worms' stomachs. Their findings were published in Current Biology in 2017.

    Federica Bertocchini, co-author of the study, says the worms' ability to break down their everyday food — beeswax — also allows them to break down plastic. ＂Wax is a complex mixture, but the basic bond in polyethylene, the carbon-carbon bond, is there as well, ＂she explains, ＂The wax worm evolved a method or system to break this bond. ＂

    Jennifer DeBruyn, a microbiologist at the University of Tennessee, who was not involved in the study, says it is not surprising that such worms can break down polyethylene. But compared with previous studies, she finds the speed of breaking down in this one exciting. The next step, DeBruyn says, will be to identify the cause of the breakdown. Is it an enzyme produced by the worm itself or by its gut microbes(肠道微生物)?

    Bertocchini agrees and hopes her team's findings might one day help employ the enzyme to break down plastics in landfills. But she expects using the chemical in some kind of industrial process — not simply ＂millions of worms thrown on top of the plastic.＂

    Google's new camera, called Clips, is a small, smart device. It comes with a case that has a clip (夹子)，but it's not designed to be worn on your clothing. Most interestingly, it uses artificial intelligence to take photography out of your hands so it can capture moments on its own.

    This roughly 2-inch by 2-inch camera, with a three-hour battery life and Gorilla Glass for toughness, is intended for candid moments, like when a child does something cute that may happen too quickly for you to pull out your smartphone.

    Onboard the Clips device, it uses machine learning algorithms (计算程序) to help capture scenes. Those algorithms include face recognition. "Once it learns that there's a face you see frequently, it'll try to get nice photos of those faces," said Juston Payne, the device's product manager. And they also want it to recognize facial expressions, which involved "training it to know what happiness looks like". The Google team also trained it to recognize what not to shoot — like when a child's hand is over the lens, or if it is tossed in a dark purse.

    The only way to see the images is by connecting the camera with your phone, as it has no screen for viewing or editing.

    Were people concerned it could seem strange? Yes, Payne admitted. But they said they addressed that by making it obvious what it is. A green light on the front signals that it is on. Besides, unlike a camera meant to monitor your home, it is not connected to the Internet.

    "This product is only possible because of the way that silicon has advanced" Payne said, noting that it was only in the past year or so that they could squeeze the technology down into a device this size. Going forward, we're likely to get more assistance from the artificial intelligence packed into our apps and gadgets.

    Have you ever noticed how Americans fill up their entire glass with ice and then pour their beverage (饮品) in, but Europeans take their drinks at room temperature? In the U. S. , we've created fridges that give you cold ice at the press of a button, but in Britain they typically serve their tap water warm.

    This tradition—if that's what you want to call it—dates back to the 19th century. During that time, it was already commonplace for most American homes to have an ice box. Ice would be harvested in northern America or Canada and shipped across the Atlantic and sold at a high price in British department stores. Can you imagine heading to Macy's to treat yourself to a block of ice?

    Putting ice in your drink started to become somewhat of a fashion(时尚)trend for the wealthy in Britain. Some would put a few cubes in their champagne and sip on their chilled drinks at high-class parties. But, like with any fashion trend, it eventually faded, mainly because the ice was just too expensive. And even once ice boxes began appearing in homes in Britain as well, Brits never took a liking to ice in their drinks.

    So, next time you travel overseas, don't feel offended (被冒犯) when your server gives you an eye roll when you ask for ice water.

    The traditional British pub is part of the scenery of British life. At the last count, there are around 50,000 of them in the UK. The oldest – Ye Olde Fighting Cocks in St. Albans – was set up in about 793.

    Because of their abundance, the names pubs take are designed to be memorable, but more than that, they are designed to be visual. Outside any traditional pub worthy of its title, you'll find a hanging signboard with an unusual and uncommon illustration(插图) that represents the name of the business. The practice is so well established that even new pubs copy it. But why do they exist at all?

    The first British pub signs were created in the 12^th century and were simple representations of beer containers and other brewing-related equipment used to tell passersby that establishments sold beer. This was Britain in the dark ages, when education was in short supply. Since most of the population was unable to read, pub signs were used to inform would-be customers that they could find a drink inside.

    The earliest uses of pub names would reference the sign directly. People would appoint to meet at "the sign of the Eagle and Child" rather than at "the Eagle and Child".

    Today the tradition remains unchanged largely out of respect for the past, but many pub signs do have some functionality. Remote country pubs often use signboards to point the way to their doors. It's a part of British culture that's rapidly disappearing – more than 20,000 pubs have closed since 1980 – but for now there are still more than enough. You can take a moment to appreciate the history and symbolism behind a pub's sign the next time you see one.