Humans are much worse at estimating risk than we think we are. While we overestimate the risk of rare but disastrous occurrences, such as being attacked by a shark, many of us seriously underestimate the risk of behaviors that reduce our lifespan (寿命), such as smoking.

    In fact, there are two types of risks — acute and chronic. Acute risks are those that may kill you immediately, such as a car accident.

    Chronic risks don't kill you immediately but rob you of your life a little at a time. If you choose to eat an unhealthy diet, for instance, you may appear to be getting away with this, but you risk developing illnesses in future that may shorten your life.

    The problem is we value things much less when they occur in the future. Distant events are abstract — we don't know how and when they might affect us -~ so we care less about them.

    Take smoking for example. It is just about the worst choice you can make for your health. Every two cigarettes that you smoke takes 30 minutes off your lifespan.

    In contrast, eating vegetables is clearly very good for you, with each serve increasing your lifespan by two hours. This is a massive health gain and clearly should be a strong motivator for you to eat healthily.

    Drinking coffee is also good for you, though with limited health gains. Each cup of coffee (assuming you drink reasonably), is associated with approximately a ten-minute gain in your lifespan.

    Even drinking alcohol may add to your lifespan, with each serve adding 30 minutes to the length of your life. But this health gain is only true for the first drink; following drinks shorten lifespan. Alcohol also causes an acute risk when consumed in excess. Too much drinking gives you a 25 in one million chance of sudden death.

    We shouldn't be too nervous about exposure to risks. Life is all about making decisions about risks and rewards, and we all have a different starting point for what we consider acceptable risks to take. Even if we don't always make the healthiest decisions, at least we can make ones that are fully informed.

    When a driver slams on the brakes to avoid hitting a pedestrian crossing the road illegally, she is making a moral decision that shifts risk from the pedestrian to the people in the car. Self-driving cars might soon have to make such ethical (道德的)judgments on their own — but settling on a universal moral code for the vehicles could be a tough task, suggests a survey.

    The largest ever survey of machine ethics, called the Moral Machine, laid out 13 possible situations in which someone's death was unavoidable. Respondents were asked to choose who to spare in situations that involved a mix of variables: young or old, rich or poor, more people or fewer. Within 18 months, the online quiz had recorded 40 million decisions made by people from 233 countries and territories.

    When the researchers analyzed these answers, they found that the nations could be divided into three groups. One contains North America and several European nations where Christianity has been the dominant (占支配地位的)religion; another includes countries such as Japan, Indonesia and Pakistan, with strong Confucian or Islamic traditions. A third group consists of countries in Central and South America, such as Colombia and Brazil. The first group showed a stronger preference for sacrificing older lives to save younger ones than did the second group, for example.

    The researchers also identified relationships between social and economic factors in a country. They found that people from relatively wealthy countries with strong institutions, such as Finland and Japan, more often chose to hit people who stepped into traffic illegally than did respondents in nations with weaker institutions, such as Nigeria or Pakistan.

    People rarely face such moral dilemmas, and some cities question whether the possible situations posed in the online quiz are relevant to the ethical and practical questions surrounding driverless cars. But the researchers argue that the findings reveal cultural differences that governments and makers of self-driving cars must take into account if they want the vehicles to gain public acceptance.

    At least Barbara Wage, who heads a group working on autonomous-vehicle ethics at Audi in Ingolstadt, Germany, says such studies are valuable. Wage argues that self-driving cars would cause fewer accidents, proportionally, than human drivers do each year—but that people might focus more on events involving robots.

    Surveys such as the Moral Machine can help to begin public discussions about these unavoidable accidents that might develop trust. "We need to come up with a social consensus," she says, "about which risks we are willing to take."

    Professor Martin's report says that children who attend a number of schools, because their parents have to move around the country, probably make slow progress in their studies. There are also signs, says Professor Martin, that an unusually large number of such children are mentally affected.

    The professor says, "It's true, my personal feeling is that children should stay in one school. Our feelings are based on research and not on any personal feeling that I or many assistants may have on the subject."

    Captain Thomas James, an army lecturer for the past 20 years and himself a father of two, said, "I've never heard such rubbish. Taking me for example, no harm is done to the education of my children who change school regularly—if they keep to the same system, as in our Army school. In my experience—and I've known quite a few of them—Army children are as well-adjusted (适应) as any others, if not better. What the professor doesn't appear to appreciate is the fact that in such situations children will adapt (适应) much better than grown-ups."

    When this was put to Professor Martin, he said that at no time has his team suggested that all such children were backward or mentally affected in some way, but simply that in their experience there was a clear tendency (倾向).

    "Our findings show that while the very bright child can deal with regular changes without harming his or her general progress in studies, the majority (大多数) of children suffer from constantly (不断地) having to enter a new learning situation."

    We've all fantasized about it—after a rough day at work, stuck in traffic with commuters (上下班的人) we'd rather not have in our personal space, and bills to pay, plus the sound of the crying baby in the apartment next door. How nice would it be to go solo and live on an island of one, population: me?

    Well, this is the reality for 84 year old Elsie Eiler of Monowi, Nebraska. She is the sole resident of her hometown, which is the smallest recognized locality in the United States.

    Looking back at the 2000 census (人口普查), the town used to have another resident: Elsie's husband Rudy. Since he died in 2004, Elsie has lived in the town by herself. She considers herself to be the mayor, treasurer, and town librarian. Her main source of income is the bar that is frequented by truckers and other people passing through—the Monowi Tavern, which she founded with her late husband back in 1971 . She received a lot of public attention after it was discovered that she was the sole resident of Monowi, and in an interview she stated that many visitors from around the world have come to meet her in Monowi.

    When asked if she ever gets lonely, she said "I know I could always move closer to my children or stay with them whenever I want, but then I'd have to make all new friends again. Hopefully I will be able to stay here. It's where I want to be."

    Vinegar is great. It makes salad, fries and dumplings taste better, and you can even clean your windows with it. And now, according to scientists, it may even help the planet's population survive climate change.

    Researchers from the RIKEN Center for Sustainable Resource Science (CSRS) in Japan have found that growing plants in vinegar makes them more resistant to droughts. This could mean that in the future, worries about climate change affecting the world's supply of food will be much lower.

    The discovery was made after the researchers studied the Arabidopsis, a plant known for its ability to survive in dry weather. It was found that when the plant was placed in drought-like conditions, it produced a chemical called acetate(醋酸盐)—the main component of vinegar.

    After discovering this, the scientists experimented further by adding acetate to the soil of other plants, and they stopped giving them water completely. After leaving the plants for 14 days, they found that the ones treated with acetate had survived, while the untreated plants had dried up and died. It's hoped that this simple method of survival could soon be used to help farmers in dry countries keep their crops alive.

    Jong Myong Kim, co-author of the study, tells Popular Science magazine that he's already been in touch with people all over the world who are interested in trying this simple and cost-effective method out for themselves from flower growing companies to amateur gardeners. Although at this point keeping thirsty plants alive isn't as easy as just pouring vinegar over them, Kim says he and his team are working on making the process as simple as possible. "Now we are trying to cooperate with some farmers, and also some companies, to make a method to apply this system," he says.

    And for those of us who always forget to ask our neighbors to water our plants when we go away, hopefully this means the end of returning home from a trip to find our favorite flowers have died.

    A 3-year-old boy who was lost in the woods for two days is now safe at home with his family. But Casey Hathaway told his rescuers that he was not alone in the rainy, freezing cold woods. He said he was with a friend — a bear.

    The child went missing on January 22. He was playing with friends at his grandmother's house in the southern state of North Carolina. When the other children returned home but Casey did not, the family searched the area for almost an hour before calling the police. Police formed a search and rescue team to look for the young boy in the nearby woods. But two days went by and still — no Casey.

    Then on January 24, someone called the police saying he heard a child crying in the woods. Police followed up on the information and found Casey at about 9:30 that night. They pulled him out of some briar. He was in good health. Casey told the rescuers that he had hung out with a black bear for two days, a bear he called his "friend".

    Sheriff Chip Hughes spoke with reporters from several news agencies. He said Casey did not say how he was able to survive in the woods for three days in the cold, rainy weather. However, the sheriff said, "He did say he had a friend in the woods that was a bear that was with him."

    Hundreds of people helped in the search and rescue efforts, including some 600 volunteers, federal police and members of the military. Officer Hughes told reporters that at no point did he think Casey had been kidnapped.

    His mother Brittany Hathaway talked with reporters from a local news agency and thanked everyone who joined the search for her son. "We just want to tell everybody that we're very thankful that you took the time out to search for Casey and prayed for him, and he's good," said his mother. "He is good, he is up and talking. He's already asked to watch Netflix. So, he's good …"