"You see someone just sitting there, looking like they're stupid," explains teenager Manny Logan excitedly. "You just run up to them, slap(掌击) them and run off. It's funny."

    The 16-year-old Logan was describing "happy slapping". It's supposed to be fun but it's a new problem in Britain. Young people will attack passers-by while their friends record the whole thing on camera phones. It was first reported in south London six months ago. But, the practice has spread to other parts of the country and videos of attacks have become popular on the Internet.

    The young people are called "hoodies" because they usually wear a sweatshirt with a hooded top. The top can be used to cover the head or face.

    One study in England published earlier this year suggested that as many as one in four teenagers is an active offender. That includes both serious crimes and small acts like not paying for a bus ticket.

    The fear of youth crime has left some parts of towns empty of ordinary people.

    So, the British government declared war on public disorder last week. The Prime Minister has supported a decision by the country's biggest shopping centre in southeast of England to ban teenagers wearing hooded tops. The clothing helps troublemakers hide from the centre's cameras.

    This week, the government is going further. It plans to force teenage offenders to wear orange jackets while they do public service. The idea is to shame them in front of others.

    But some teenagers and experts have complained that, in their rush to stop the hoodies, politicians risk tarring all teenagers with the same brush.

    Recently my husband had his Achilles tendon（跟腱） cut when feeding a chicken. When sitting in the doctor's office waiting for surgery stressfully, I decided to treat myself for a minute and start to read about “The Little House on the Prairie”. Suddenly I felt my life seemed like a slack（懈怠） compared to the Ingalls who do all their washing and cooking but they feel so happy. Their every happiness is created from the work with their own hands. Yet I'm walking around feeling sorry for myself because I'm picking up the slack! So I'm thinking “Work it out! Get up and get busy.”

    It really is true. I realize that I'm happiest when accomplishing tangible(有形的) productive work—working in the yard and washing my dishes—brings me happiness. This does not surprise Kelly Lambert Ph.D. She has been researching the phenomenon she calls “effort-rewards”. When you do meaningful work with your hands, a kind of neurochemical feedback floods your brain with dopamine and serotonin. These happy brain chemicals are natural antidepressants, and we've evolved to release them both to reward ourselves for working with our hands and to motivate ourselves to do it some more. Dr. Lambert says Americans have become more depressed in recent years and at the same time we've experienced a decrease in purposeful physical activity. Did we lose something vital to our mental health when we started pushing buttons instead of ploughing the fields?

    Dr. Pansinski says she gets that happy look when she prepares a meal at the end of a day. “We are programmed to reward ourselves when we accomplish things with our hands. For so many people, it just feels as though everything's going so fast—life, kids, hundreds of e-mails a day. There is so little you can really see and hold on to. Working with one's hands is a way to slow down, to take pleasure in life again.”

    If you see a group of people dancing and singing on the street or in the railway station, you don't need to feel surprised. They are a flash mob(快闪族), which is a group of people who come together suddenly in a public place, do something unusual for a brief period of time, and then quickly break up. They are usually organized with the help of the Internet or other digital communication network. At a predetermined(预先决定的) time, they gather and perform some distractions(消遣) such as waving their hands and exchanging books. Then, they quickly break up before the police can arrive. Using mobile phones, the flash mob can change its location if the first one has been replaced for any reason.

    Bill Lasik, senior editor of Harper's Magazine, organized the first flash mob in Manhattan in May 2003 and the first successful flash mob came together on June 3, 2003 —after the first attempt failed at Macy's department store. Lasik claimed that the activity was designed to make fun of hipsters(赶时髦的人), and call attention to the cultural atmosphere.

    Flash mob gatherings can sometimes shock people. Such an activity might seem amusing and untrue, but it also might frighten people who are not aware of what is taking place. Undoubtedly, flash mobs can serve as good political tools in any direction. They also have great economic potential, such as using flash mobs to advertise a product.

    The flash mob is now becoming more and more popular. People use it to do many things. For example, in 2009, Michael Jackson's fans took part in a flash mob to remember him. Hundreds of his fans gathered singing and dancing Michael's famous song “Beat It” together. Flash mobs give people from all walks of life an opportunity to come together to create a memory.

    Robots make me nervous—especially the ones which seem to think for themselves. I was embarrassed to admit this till I heard that Bill Gates, the founder of Microsoft, felt the same way.

Gates said in an interview with the social networking and news website Reddit: "I am in the camp that is concerned about super intelligence. First the machines will do a lot of jobs for us and not be super intelligent．That should be positive if we manage well. A few decades after that, though, the intelligence is strong enough to be a concern."

    Well, maybe I don't have to worry about my computer and kitchen equipment yet. After I use them I can always pull the plug. But in the future, machines might find a way to prevent us from switching them off. There's a terrible thought!

    Maybe the problem with computers too clever for us is not that they are evil like some we've seen in sci-fi movies. What could put us in danger is that they might be too efficient. That's what philosopher Nick Bostrom from Oxford University believes. He says that machines are indifferent to humans and in pursuit of their own goals，the destruction of people might be just additional damage. Bostrom gives us an example: A machine which might have its only goal to produce as many paperclips as possible might look at human bodies as extra material for paperclips and go after you. Because it is, well, a machine, it would not take pity on you.

    It's a good thing that American writer Isaac Asimov thought about how far robots can go and left us his three rules of robotics. They state that a robot may not hurt a human being or allow the human being to come to harm.

I'm glad my machines at home are "dumb". All my cleaner wants to take over is the carpet in my living room. Let's hope they don't create an appliance which wants to take over the world!

An aspirin a day keeps the doctor away

    Dr. Tim Johnson discusses evidence of a daily dose of aspirin's benefits. That's not the saying, but doctors have agreed, for about a generation, that an aspirin a day is good for you. It may reduce the risk of heart attacks or strokes by 20 percent or more.

    The US Preventive Services Task Force, an independent group convened by the Department of Health and Human Services, has published guidelines that it says should end the confusion.

    The key points:

    ⒈Men should start a daily aspirin at age 45, mainly to protect against heart attacks.

    ⒉Women should start at 55, mainly to protect against stroke.

    ⒊For both sexes, a baby aspirin-typically 81 milligram a day-will do the job. There is no evidence that a large dose makes a difference.

    ⒋And both sexes should stop by age 80, unless their doctors say otherwise. As you get older, there's a greater risk of bleeding in the brain or the digestive system, a risk that is small but can be deadly in some cases.

    If people start taking aspirin as the guidelines, doctors say their risk of heart attacks will drop by about 20 percent. "People may ask themselves 'Am I at risk for a heart attack or a stroke?'" said Dr. Randal Thomas, director of cardiovas-cular health at the Mayo Clinic in Minnesota "If you are age 45 and male, if you're above age 55 and female, the answer is most likely yes, and you will most likely benefit from taking a small dose of aspirin a day.

Civilization began with agriculture, and though humanity has changed significantly, agriculture remains very important. In certain countries, its significance is more apparent, but the reality is that every country in the world depends on agriculture for one thing or another.

It provides employment. Whether it's working as a farmer, a harvester, a technician for farm equipment or a scientist, there are plenty of jobs available in this field. In developing countries, agricultural jobs help reduce high rates of unemployment.

It's crucial to a country's development. Economic development is tied to a country's agricultural sector. When trade, national avenue, and employment are combined in a positive way, a country enjoys reduced poverty and boosted economic growth. Because strong agriculture results in benefits fairly quickly, focusing on it is one of the best ways to speed up development and improve a country's standing across the globe.

It drives innovation in technology. Because healthy agriculture is so essential to a country's well-being, it's been the setting of some of the most exciting innovations in technology. Through artificial intelligence, blockchain software, and more, scientists and farmers have been figuring out ways to increase crop productivity, use less water, and reduce negative impacts on the environment. For scientists and tech companies, agribusiness is one of the most fascinating and productive fields to work in.

It's the source of our food supply. Arguably, the most important aspect of agriculture is that it's the source of the world's food supply. No matter where or what you are eating, the ingredients in your meals come from somewhere. All roads lead to agriculture. In countries dealing with food insecurity and severe malnutrition, their agricultural sectors are suffering. When agriculture thrives(蓬勃发展), fewer people go hungry.

It can help heal the environment. Agriculture possesses the power to cause harm or heal. When farmers prioritize biodiversity on their land, it benefits the earth. Having more biodiversity results in healthier soil, better water conservation, and healthier pollinators(传粉者).

All in all, agriculture plays a critical role in the entire life of a given economy. Agriculture culture is the backbone of the economic system of a given country.