Exercise may help to safeguard the mind against depression through previously unknown effects on working muscles, according to a new study involving mice.

    Mental health experts have long been aware that even mild, repeated stress can contribute to the development of depression and other mood disorders in animals and people. Scientists have also known that exercise seems to cushion against depression. But precisely how exercise, a physical activity can lessen someone's risk for depression, a mood state, has been mysterious. So for the new study, researchers at the Karolinska Institute in Stockholm studied the brains and behavior of mice in a complicated and novel fashion.

    We can't ask mice if they are feeling cheerful or in low spirits. Instead, researchers have pictured certain behaviors that indicate depression in mice. If animals lose weight, stop seeking out a sugar solution when it's available — because, probably, they no longer experience normal pleasures — or give up trying to escape from the cold-water zone just freeze in place, they are categorized as depressed. And in the new experiment, after five weeks of frequent but low-level stress, such as being lightly shocked, mice displayed exactly those behaviors. They became depressed.

    The scientists could then have tested whether exercise blunts (延缓) the risk of developing depression after stress by having mice run first. But, frankly, from earlier research, they wanted to know how, so they bred pre-exercised mice. A wealth of earlier research by these scientists and others had shown that aerobic exercise, in both mice and people, increases the production within muscles of an enzyme (酶) called PGC-1alpha. The Karolinska scientists suspected that this enzyme somehow creates conditions within the body that protect the brain against depression. Then, the scientists exposed the animals, which without exercising, were in high levels of PGC-1alpha to five weeks of mild stress. The mice responded with slight symptoms of worry. But they did not develop depression. They continued to seek out sugar and fought to get out of the cold-water zone. Their high levels of PGC-1alpha appeared to make them depression-resistant. Finally, to ensure that these findings are relevant to people, the researchers had a group of adult volunteers complete three weeks of frequent endurance training, consisting of 40 to 50 minutes of moderate cycling or jogging. The scientists conducted muscle biopsies (活体检查) before and after the program and found that by the end of the three weeks, the volunteers' muscle cells contained substantially more PGC-1alpha than at the study's start. The finding of these results, in the simplest terms, is that “you reduce the risk of getting depression when you exercise,” said Maria Lindskog, a researcher at the Karolinska Institute.

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    In the famous fairy tale, Snow White eats the Queen's apple and falls victim to a curse（诅咒）;in Shakespeare's novel, Romeo drinks the poison and dies; some ancient Chinese emperors took pellets（药丸）that contained mercury（水银）, believing that it would make them immortal, but they died afterward.

    Poison has long been an important ingredient in literature and history, and it seems to always be associated with evil, danger and death. But how much do you really know about poison?

    An exhibition, The Power of Poison, opened last month at the American Museum of Natural History in New York, intended to give the audience a more vivid understanding of poison.

    The museum tour starts in a rainforest setting, where you can see live examples of some of the most poisonous animals: caterpillars（毛毛虫）, frogs and spiders. Golden poison frogs, for instance, aren't much bigger than a coin, but their skin is covered with a poison that can cut off the signaling power of your nerves, and a single frog has enough venom to kill 10 grown humans.

    "Poisons can be bad for some things," Michael Novacek, senior vice president of the museum, told NBC News. "Yet they can also be good for others."

    A poisonous chemical found in the yew tree is effective against cancer, which is what led to the invention of a cancer-fighting drug called Taxol.

    The benefits from natural poisons are not limited to just medicine. Believe it or not, many substances（物质）that we regularly ingest（摄入）-chili, coffee and chocolate-owe their special flavors or stimulating（提神的）effects to chemicals that plants make to poison insects.

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    It's generally believed that people act the way they do because of their personalities and attitudes. They recycle their garbage because they care about the environment. They pay $5 for a caramel brulee latte because they like expensive coffee drinks.

    It's undeniable that behavior comes from our inner dispositions(性情), but in many instances we also draw inferences about who we are, as suggested by the social psychologist Daryl Bern, by observing our own behavior. We can be strangers to ourselves. If we knew our own minds, why should we need to guess what our preferences are from our behavior? If our minds were an open book, we would know exactly how much we care about the environment or like lattes. Actually, we often need to look to our behavior to figure out who we are.

    Moreover, we don't just use our behavior to learn about our particular types of character — we infer characters that weren't there before. Our behavior is often shaped by little pressures around us, which we fail to recognize. Maybe we recycle because our wives and neighbors would disapprove if we didn't. Maybe we buy lattes in order to impress the people around us. We should not mistakenly believe that we always behave as a result of some inner disposition.

    Whatever pressures there can be or inferences one can make, people become what they do, though it may not be in compliance(符合) with their true desires. Therefore, we should all bear in mind Kurt Vonnegut's advice: “We are what we pretend to be, so we must be careful about what we pretend to be.”

First aid means the aid or the help that can be given to an injured person first, that is, before any other help arrives. Nowadays there is usually a telephone not far away and the first we should do, if a serious accident happens, is to call for an ambulance. Sometimes quick action by us may save someone's life.

Shock. People often suffer from shock after receiving an injury, sometimes even when the injury is a small one. The face turns grey, and the skin becomes damp and cold. They breathe quickly. They should be kept warm. Cover them with a blanket and give them a warm drink.

Broken bones. Do not move the patient. Send for an ambulance at once.

Bleeding. A little bleeding doesn't harm. It washes dirt from the wound. But if the bleeding continues, try to stop it by placing a clean cloth firmly over the wound until the bleeding stops or help arrives.

Poison. A person who has taken poison should be taken to a hospital at once. With some poisons, sleeping pills, for example, it is a good thing to make the patient throw up by pressing your fingers down his throat.

Remember: When an accident happens, send someone to telephone for an ambulance at once. Keep the injured person warm and quiet. Give him plenty of air. Do not let other people crowd around him.

Over the years, electronic commerce or e-commerce has grown rapidly. The rise of e-commerce large enterprises such as Amazon and Alibaba in the mid-90s changed the face of the retail (零售) industry. E-commerce may be thought of as an open, global marketplace or a digital version of mail-order catalogue (目录). Nearly every imaginable product and service is available through e-commerce dealings these days.

Many young entrepreneurs have dived into the e-commerce world, ambitious and hoping to succeed. Some, like Mitchell Zvagelskiy. Zvagelskiy is the co-founder of Scale Online, a fast-growing startup in California and runs several e-commerce stores. Zvagelskiy and his business partner began opening online stores and building a team to grow them, allowing the stores to earn as much as $100.000＋ in monthly revenue. Zvagelskiy owes his success to teamwork and his willingness to seize opportunity.

"Being able to do this all by the age of 20 is something I didn't expect and would not be able to do if I constantly listened to other people and just went the typical college then job route," he said. "Life can change fast if you change fast."

Thanks to the rapid success of his YouTube channel, Mitchell has been able to not only make great profit from his companies, but help others in starting and growing their own e-commerce stores too. "My meaning of success arises from my relationships with other people," he said. "By focusing on building strong relationships with others, I'm able to partner up and work with like-minded individuals in finding market opportunities and solving whatever problems people are facing."

A new study estimates more than 1 billion people worldwide are currently living with obesity. People with obesity are considered medically overweight. The study, published in the medical publication The Lancet, said that one in eight people are obese. Researchers said around 43 percent of adults were overweight in 2022. Obesity among adults has more than doubled since 1990. Among young people aged 5 to 19, the obesity rate increased by four times during the same period.

"A staggering number of people are living with obesity, and severe obesity is strongly linked to a long list of health problems and an early death." declared the lead writer of the study, Majid Ezzati, a professor at Imperial College London.

The WHO noted that at the World Health Assembly in 2022, member states agreed to an agency plan to fight obesity. So far, 31 governments "are now leading the way" to reduce obesity by carrying out goals of the plan.

These include government measures to enact new rules on "harmful" marketing of unhealthy food and drinks to children. In addition, governments are aiming to improve school and nutrition policies. They are also seeking price reductions for healthy foods, to increase public awareness about healthy diets and exercise and to strengthen requirements for physical activity in schools.

Imperial College's Ezzati said that obesity rates are not rising in many wealthier nations. But they are quickly increasing in other countries. He noted that some countries have many underweight people, meaning the nations are facing what he called a "double burden" of nutrition problems.

Branca is head of nutrition at the WHO. He told reporters, "In the past, we have been thinking of obesity as a problem of the rich, but obesity is a problem of the world. Although new obesity drugs — such as Ozempic and Wegovy — could be helpful tools in reducing obesity, they noted that the cost and availability of the drugs might increase inequality."