Fighting racial stereotypes（模式化）on US campuses often begins by putting students of different ethnic backgrounds together — under one dormitory roof.

    Sam Boakye was a freshman at Ohio State University and the only black student on his floor. He was determined to get good grades — in part to make sure his white roommate had no basis for negative racial views. "You're pushed to do better, to challenge the stereotype that black people are not that smart," he told the New York Times.

    Several recent studies have found that having a roommate of a different race can reduce prejudice(偏见), diversify(使多样化) friendships and even promote students' academic performance. In a study by Ohio State psychology professor Russell Fazio, black freshmen who came to college with high test scores earned better grades if they had a white roommate—even if the roommate's test scores were low. Another study on student interaction by Duke University suggests that freshmen with roommates of a different race were the most likely to diversif“y their friendships. Just having diversity in classrooms doesn't do anything to increase interracial friendships," said Claudia Buchman, an author of the Duke study. “But living together with a different-race roommate does lead to more interracial friendships."

    There are, however, some problems with such room assignments. Fazio's study found that three times as many randomly(随机地) assigned interracial roommates weren't living together at the end of the semester, compared with white roommates. Interracial roommates also spent less time together, had fewer joint activities and were less involved with each other's friends than white pairs.

    As for Boakye, this is not the case. "A lot of white students come without much exposure（暴露）to diversity, so when their first interaction with a black guy isn't bad, they will make more black friends. I think I made a good impression on my freshman roommate. I saw him this year, and he said, "Hey dude, you're not the only black friend I have. That felt good."

    A Japanese company, Next Technology, has created a robot dog that can tell you how bad your feet smell, by using a powerful sensor fixed in its nose. If you feet don't have a bad smell. Hana-chan will happily wag its tail, if it's exposed to feet that are mildly smelly, it'll start to bark, and if they give off an extremely bad smell, it'll just fall over like the smell caused it to faint(昏倒).

    Foot odor (脚臭) is a big deal in Japan, where it's a custom for people to take off their shoes whenever they enter someone's home. In fact, exposing others to bodily odors can be considered annoyance in Japan. Some of the most brilliant minds in the country's tech industry have been trying to solve this problem. Last year, Thanko started selling axmpit (腋窝) fans designed to keep people's armpits nice and dry Now, we have Hana-chan.

    The robot dog has a special sensor for a nose, and can tell you if your feet smell just by sniffing them for a few seconds. According to some media reports, Hana-chan can help solve the problem of extremely smelly feet by spraying them with air freshener, but it's unclear whether this feature comes built-in, or if you'll have to pay extra for it.

    According to researchers at NextTechnology, the idea for Hana-chan was inspired by a person who desperately wanted some way to know if his feet smelled. "He told us his daughter had said his feet were smelly, " NextTechnology's Kimika Tsuji said. “But he didn't want to know how bad the odor was because he would feel hurt. That's why we developed this cute robot. "

    You may be able to make Hana-chan faint with your smelly feet, but it can have the same effect on budget-conscious people. NextTechnology plans to start selling the feet-smelling robot dog for ￥100, 000 ($9, 280) next May.

    Some materials are obtained from natural resources that are changed by chemical processes in a laboratory. The resulting artificial materials are synthetic, or human-made.

    Plastic is a synthetic substance, obtained from petroleum, a fossil fuel. The molecules（分子）in petroleum are split and then linked into chains. Plastic is an example of a polymer, a material made of repeating patterns of atoms linked together. Most polymers are synthetic. They are made by polymerization, the process of chemically linking many smaller molecules to form a larger molecule that has different physical features. Some polymers, such as proteins, occur naturally.

    Plastic is a key component of many products. When heated into an almost-liquid form, plastic can be made into fibers, sheets, or molds（模具）. It can be mixed with other elements to remain flexible, or it can harden into a solid. Plastic fibers can be made into clothing or carpeting. Sheets of plastic can be made into plates. Molded plastic can be sued for protective helmets or car bumpers.

    Most plastics can be reheated and remolded repeatedly. This feature makes plastic very easy to use. Polymers can be pulled into fine strings or molded into almost any kind of shape. For example, tubes of plastic can be shaped into bottles by different processes. One such process is extrusion blow-molding. Most plastics are also resistant to many chemicals that might harm other materials. This quality is the reason that so many cleaning liquids are packaged in plastic bottles.

    Plastics are good insulators that can stop electricity or heat to pass through. Look around your kitchen, and observe where plastics are used. Pot handles are sometimes made of plastic, as are cooking tools, toaster controls, and microwave cookware. Food-storage wraps and containers may be made of plastic. Take a walk outdoors, and note all the plastic items you see. Gardening tools, such as watering cans and sprayers, are often made of plastic. Swings and slides made of plastic do not become as hot as metal, so they are safer for play. Because plastics can be heated, remolded, and made into something else, they can be recycled and reused.

Sea, Sun, Sand and South Africa: Readers' Favorite Beaches

    The Wild Coast five-day hike from Kei Mouth to Coffee Bay in South Africa is surely the best experience for beach lovers.

    Robben Island beaches

    On a visit to the prison museum here, be sure to leave time to explore the island's beaches. Few visitors realize that the island's shores are the natural habitat of sizable penguins: enjoy watching them with far fewer tourists here. Bird life is plentiful and includes oystercatchers, ibis, egrets and cormorants. Sharks and dolphins can often be spotted offshore too.

    Sand, sea and sculpture, Durban

    There's more to Durban's Golden Mile than sunbathing and surfing. Not only is there a gallery of sand sculptures(雕像) and drawings, but Lucas, one of the best local artists, offers lessons. His amazing rhino(犀牛) is the only permanent item in a frequently changing exhibition. Lucas charges a modest R50 (£3) for a fun and surprisingly physical hour of creativity. Or, you could ask him to create a personalized sculpture for a special occasion.

    Paternoster, Western Cape

    Paternoster is a small beach community about 150 km north of Cape Town. The town has a number of rentals(租赁), all the Cape Dutch architecture you could want for a weekend away and some great food. Long walks on the beach, eating and drinking and watching the fishing boats make for a peaceful break. And, unlike in Cape Town, you can dip your toes in the sea without your legs freezing solid.

When it comes to sitting properly, we all know the correct way even if we don't do it to the letter. No crossed legs, bottoms touching the back of the chair and feet on the ground. But even if you're doing it right, sitting for long periods is shockingly bad for you. It has been described as the new smoking, linked to heart disease and even cancer. There is no doubt we should all try to do less of it. But perhaps we could also do it better.

A classic survey, published in 1953, described 100 different sitting postures adopted by 480 cultures around the world. Among the most common were sitting cross-legged, kneeling and the deep squat (深蹲), with feet flat on the ground and bottoms resting on or just above it. Even in Western cultures, these are preferred sitting positions among young children. But Westerners tend to prefer chair use from an early age, insisting children sit on seats in school.

One big problem with this desire for chairs is that they make sitting so, well, sedentary (久坐不动的). Consider the Hadza, a group of hunter-gatherer people in Tanzania. They spend around 9 hours a day sitting. However, they squat and sit on the ground in various positions, and this involves high levels of muscle activity. The supportive nature of chairs, with their high backs and armrests, removes this effort perhaps the reason that people love them.

So what's the best way to sit? Josette Bettany-SaItikov at Teesside University, UK has found that kneeling can help keep the spine in a better position as does squatting. We might also take inspiration from traditional cultures like the Hadza. "Use a variety of postures and preferably not just still postures but some which allow movement," says Bettany-Saltikov.

Bettany-Saltikov believes that we should be rethinking what it means to do a desk job. "We still need to design workplaces that enable people to be productive while being lightly active, like with under-table cycling or walking desks," she says. For now, if your job is sedentary, don't forget to stand up regularly and move around.