On Monday, the Centers for Disease Control and Prevention predicted that 42% of Americans could be overweight by 2030. Our expanding waistlines lead to not only a medical problem, but according to a recent article In The New York Times, it could also endanger personal safety in some situations—in an airplane crash, for example.

    The New York Times' Christen Negroni reports that engineers and scientists are questioning whether airplane seats are adequately constructed to protect overweight travelers. Government standards for airplane seat strength（强度）— first set moe than 60 years ago — require that the seats be made for a passenger weighing 170 pounds (77kg). Today, the average American man weighs nearly 194 pounds (88kg) and the average woman 165 pounds (75kg). Negroni reports:

    “If a heavier person completely fills seat, the seat is not likely to behave as intended during a crash,” said Robert Salazar, the leading scientist at the Center for Applied Biomechanics at the University of Virginia. “The energy absorption that is built into the aircraft seat is likely to be overpowered and the passengers will not be protected properly.”

    “Nor would the injury be limited to that passenger only,” Dr. Salzar said. “If a seat or a seat belt fails,” he said, “those people who are seated nearby could be endangered from ‘the uncontrolled movements of the passenger'.”

    Most complaints about airplane seats focus on their lack of comfort and high ticket price, and whether overweight passengers should be made to buy two seats. But The New York Times' article brings up another reason to feel anxious about flying. Investigators of the issue got in touch with the airplane seat and seat belt makers, but they refused to comment on the problem. Experts agreed that crash testing should be done with overweight dummies （人体模型）. Both airplane seats and seat belts should be tested, they said.

    Fortunately, however, according to Nora Marshall, a senior adviser at the National Transportation Safety Board, the board's investigators have never seen an accident involving a commercial plane in which the weight of a passenger was a problem.

    You want to run across the street to catch the bus which is leaving soon? But wait! You'd better not. If a policeman sees you, you'll have to pay a fine. New traffic laws say that if people cross the street when the light is red, they can be fined as much as 50 yuan.

    Traffic accidents killed more than 100,000 people in China one year. Chinese cities have more cars than ever. Drivers and pedestrians must work together to make the streets safer.

    The law has new rules for drivers and pedestrians. Drivers have to slow down when they are close to crosswalks. If people are in a crosswalk, cars must stop to let them pass. There are rules for bus drivers, too. If bus drivers, smoke, drink or make phone calls while driving, they can be fined. Buses that carry too many people are also against the law.

    Pedestrians will have to walk more safely under the new law. They must cross streets at crosswalks. Also, they shouldn't climb over the fences (栅栏) along streets.

    Do you bike to school? It's not a good idea to carry classmates on the back. You could be fined 50 yuan. And stay in the bike lane (车道), when you' re riding. The big roads are for cars and buses.

    Do you like to ride your uncle's motorbike? When you put on your helmet (头盔), ask him to put one on, too. People on motorbikes must wear helmets, the new law says. If they don't, they'll have to pay 200 yuan.

    Do you ride in cars often? Don't forget to put on your seat belt (安全带), even if you're going for a short taxi ride. It could save your life.

    If you see a hit-and-run(肇事逃逸), tell the police. They may give you a reward (奖赏).And don't be afraid to help people to the hospital if they are hurt in an accident. Don't worry about money. The new law says that doctors must take care of them even if they can't pay right away.

    Every time your fingers touch your cell phone, they leave behind trace of amounts of chemicals. And each chemical offers clues to you and your activities. By studying them, scientists might be able to piece together a story about your recent life, a new study finds.

    A molecule (分子) is a group of atoms. It is the smallest amounts of some chemicals. Your skin is covered in molecules picked up by everything you touched. With each new thing your skin contacts, you leave behind some small share of what it'd touched earlier.

    Researchers at the University of California, San Diego (UCSD) recently studied such chemical leftovers on the phones of 39 volunteers. The study was led by biochemist Amina Bouslimani. To explore those residues (剩余物), the UCSD team wiped the surface of each volunteer's phone with a cotton swab (药签). The scientists also swabbed each person's right hand. Then the researchers compared the chemicals found on each cell phone.

    The scientists discovered as many of the molecules as they could. They then compared those to a database of chemicals. Pieter Dorrestein, a UCSD pharmaceutical chemist, had helped set up that database a few years earlier, which contains various substances, including spices, caffeine and medicines.

    Traces of everything from hundreds to thousands of different molecules turned up on each phone. The molecules suggested what had been in the body, and what each person had handled before touching the phone. From all these molecules, Bouslimani says, “We could tell if a person is likely female, uses high-end cosmetics (化妆品), colors her hair, drinks coffee, prefers beer over wine or likes spicy food.”

    Police already use molecular analyses to look for traces of explosives or illegal drugs. To date, Dorrestein says, he's never heard of police using phone residues to narrow down behaviour clues to search for a suspect. But detectives might one day use such data to track down someone who left a phone behind at a crime scene.

    You often can choose a private setting when you browse(浏览) the internet. But be forewarned: It may not afford nearly as much privacy as you expect. That's the finding of a new study.

    Major web browsers, such as Google's Chrome and Apple's Safari, often a private-browsing option. It's sometimes referred to as “incognito.” This option lets you surf the Internet browser and saves a record into its history of each page that you visited. And what sites you visit won't affect the suggestions your browser makes the next time you're filling out an online form.

Many people believe—incorrectly— that the incognito setting protects them more broadly. Most believe it even after reading a web browser's explanation of the incognito mode.

    For instance, a new study had 460 people read web browsers' descriptions of private browsing. Each person read one of 13 descriptions. Then the participants answered questions about how private they thought their browsing would be while using this tool. The volunteers didn't understand the incognito mode. This was true no matter which browser explanation they had read. The researchers reported their findings on April 26 at the 2018 World Wide Web Conference in Lyon, France.

    More than half of the volunteers thought that if they logged into a Google account through a private window, Google wouldn't keep a record of their search history. Not true. And about one in every four participants thought private browsing hid their device's IP address. That's wrong, too.

    Blase Ur was one of the study's authors. He's an expert in computer security and privacy in Illinois at the University of Chicago. Companies could clear up this confusion by giving better explanations of the incognito mode, his team says. For example, the browsers should avoid vague（模糊).The web browser Opera, for instance, promises users that “your secrets are safe.” Nope Firefox encourages users to “browse like no one's watching.” In fact, someone might be. (If you'd like to know more about the research information, please click here.)

    In the space of just two years, the app Douyin, created by Beijing-based company ByteDance, has gathered more than half a billion users—around 40%of them outside China—who share short videos of themselves lip-syncing (假唱), cooking, dancing or just being silly. What sets ByteDance apart is its success in the social media category, which is controlled by Facebook, Twitter and Snap—all Western companies.

    ByteDance calls itself an artificial intelligence company. It uses machine learning and algorithms (算法) to figure out what people like most and give them more of what they want to see. On Douyin, people can edit and beautify 15-second videos before posting them online. The app has even made a phrase to describe people glued to their customized feeds: "shua Douyin" or "scrolling through Douyin". Last year, the company released TikTok, the overseas version of Douyin. ByteDance's growing video empire has made it the world's fifth biggest app maker. ByteDance says TikTok and Douyin together have more than 500 million monthly active users.

    Investors like ByteDance because its hundreds of millions of users attract a lot of advertising money. The video apps are lucrative because they attract a lot of users in their teens and 20s, who are more generous with the money. ByteDance also makes money through income sharing deals. People on TikTok, for example, can buy digital coins to give to other people on the app—like throwing money in a performer's tip jar. ByteDance takes a cut of those earnings.

    ByteDance's founder and CEO is Zhang Yiming, a 35-year-old former Microsoft employee. People who have worked with Zhang describe him as someone who thinks deeply about technology and spends much of his free time writing code.

    Like Facebook and Twitter, ByteDance is also battling fake news and inappropriate content. ByteDance promises to add thousands more employees to review content on Douyin.