When did you last see a polar bear(北极熊）? On a trip to a zoo, perhaps? If you had attended a winter activity in New York a few years ago, you would have seen a whole polar bear club. These "Polar Bears" are people who meet frequently in the winter to swim in freezing cold water. That day, the air temperature was 3℃,and the water temperature was a little higher. The members of the Polar Bear Club at Coney Island, New York are usually about the age of 60.Members must satisfy two requirements. First, they must get along well with everyone else in the group; this is very important because there are so many different kinds of people in the club. Polar Bears must also agree to swim outdoors at least twice a month from November through February.

    Doctors don't agree about the medical effects of cold-winter swimming. Some are worried about the dangers of a condition in which the body's temperature drops so low that finally the heart stops. Other doctors, however, point out that there is more danger of a heart attack during summer swimming because the difference between the air temperature and water temperature is much greater in summer than in winter.

    The Polar Bears themselves are satisfied with the benefits of cold-water swimming. They say that their favorite form of exercise is very good for the circulatory system(循环系统）because it forces the blood to move fast to keep the body warm. Cold-water swimmers usually turn bright red after a few minutes in the water. A person who turns blue probably has a very poor circulatory system and should not try cold-water swimming.

    The main benefits of cold-water swimming are probably mental. The Polar Bears love to swim all year round; they find it fun and relaxing. As one 70-year-old woman says," When I go into water, I pour my troubles into the ocean and let them float away."

    MOOCs (Massive Open Online Courses) are free, but without tutoring, and are open to anyone, anywhere in the world. The courses are flexible — normally three to five hours of study a week — done at any time, short (5 to 10 weeks) and video-rich. They are also heavily dependent on crowd sourcing: you can discuss a course with fellow students through online forums, discussion boards and peer review. Students don't have to finish the courses, pass assessments or do assignments, but, if they do, they get a certification of participation.

    The Open University launched FutureLearn, the UK's answer to US platforms such as Coursera, EdX and Udacity, which have been offering MOOCs from top US universities for the past two years. The response has been incredible, with more than three million people registering worldwide. Meanwhile, in 2012, Edinburgh University became the first non-US institution to join Coursera's partnership, comprising 13 universities. “We already run 50 online master's degrees, so this was a logical expansion,” says Professor Jeff Haywood, Edinburgh's vice-principal. “It's an investment in teaching methods research. How am I going to teach introductory philosophy to 100,000 people? That's what I call educational R&D.” He adds “If you look ahead 10 years, you'd expect all students graduating to have taken some online courses, so you've got to research that. Our MOOCs are no more in competition with our degrees than a lifelong learning course because they don't carry credits.”

    Cooperation is key, Haywood stresses. It is far better to offer 20-30 courses in your own areas of expertise (专门技能) and let other institutions do likewise. Professor Mike Sharples, FutureLearn's academic lead, goes further: “We've tied the elements available before into a package of courses offered by leading universities worldwide on a new software platform, with a new way of promoting it and also a new social-learning teaching method. You won't just receive an exam, but be able to discuss and mark each other's assignments.”

    Bath University, one of more than 20 universities working with FutureLearn, launches its first course, Inside Cancer, next January, and regards MOOCs as a way of breaking down age barriers. “There's no reason why someone doing GCSEs should not look at our MOOCs and get quite a way through them, or someone at PhD level and beyond,” says Professor Bernie Morley, expert for learning and teaching.

    As a result of pollution, Lake Erie, on the borders of the USA and Canada, is now without any living things.

    Pollution in water is not simply a matter of “poisons” killing large numbers of fish overnight, Very often the effects of pollution are not noticed for many months or years because the first organisms（生物体）to be affected are either plants or plankton. But these organisms are the food of fish and birds and other creatures. When this food disappears, the fish and birds die too. In this way a whole food chain can be wiped out, and it's not until dead fish and water birds are seen at the river's edge or on the seashore that people realize what is happening.

    Where do the substances which pollute the water come from? There are two main sources of sewage（污水）and industrial waste . As more detergent（洗涤剂）is used in the home, so more of it is finally put into our rivers, lakes and seas . Detergents harm water birds, dissolving the natural substances which keep their feathers water - proof. Sewage itself, if not properly treated, makes the water dirty and prevents all forms of life in rivers and the sea from receiving the oxygen they need. Industrial waste is even more harmful as there are many highly poisonous things in it, such as copper and lead（铅）.

    So, if we want to stop this pollution, the answer is simple: sewage and industrial waste must be made clear before flowing into the water. It may already be too late to save some rivers and lakes, but others can still be saved if the correct action is taken at once.

    There are many programs for high school students today that help isolated teenagers cope with loneliness. However, loneliness is not only an issue for teens but also an important and rarely acknowledged one in the elderly.

    In Britain, Tracey Crouch was appointed to be the first Minister of Loneliness in order to address the issues caused by loneliness. This is the first time such a position has been created.

    In Britain, there are around 9 million people who say they are lonely frequently. In Germany, a study conducted by Ruhr University Bochum found that 20 percent of people over the age of 85 felt lonely, and 14 percent of those between age 45 and 65 felt socially isolated. In the United States, more than 25 percent of the population lives alone, more than 50 percent are unmarried.

    Isolation is generally associated with cardiovascular disease, depression, obesity, and anxiety. Additionally, the stress from loneliness can cause your cells to change on a molecular(分子)level that reduces its abilities to defend your body against diseases. In fact, doctors believe having feelings of loneliness is equivalent to smoking 15 cigarettes per day in regard to its impact on health!

    In Britain, the new Minister of Loneliness will help establish government policies on the issue and fund charities to devote their efforts towards aiding loneliness. There are charities that link lonely seniors to high school students in order to give them a line of communication whenever they feel lonely!

    The possibilities for the new Minister of Loneliness are endless. For example, she can provide education services to household businesses so that they can identify lonely customers if they see one. Loneliness fits into the category of being a social issue that must be monitored by the entire community in order to help those in need. Hence, government involvement in medical services and care for seniors and others is essential for happy seniors.

    Food sometimes gets poisoned with harmful things. A person who eats such food can get an illness called food poisoning. Food poisoning is usually not serious, but some types are deadly. The symptoms of food poisoning usually begin within hours of eating the poisoned food. Fever is one of the most common symptoms.

    Certain microorganisms(微生物)cause most types of food poisoning. Bacteria and other microorganisms can poison eggs, meat, vegetables, and many other foods. After entering the body, these tiny living things release(释放)poisons that make people sick.

    Some chemicals can also cause food poisoning. They are often added to food while it is being grown, processed, or prepared. For example, many farmers spray chemicals on crops to kill weeds and insects. Some people may have a bad reaction to those chemicals when they eat the crops.

    Some plants and animals contain natural poisons that are harmful to people. These include certain kinds of seafood, grains, nuts, seeds, beans, and mushrooms.

    When people handle food properly, the risk of food poisoning is very small. Microorganisms multiply rapidly in dirty places and in warm temperatures. This means that people should never touch food with dirty hands or put food on unwashed surfaces. Food should be kept in a refrigerator to stop microorganisms from growing. Meat needs to be cooked thoroughly to kill any dangerous microorganisms. People should also wash food covered with chemicals before eating it. Finally, people should not eat wild mushrooms or other foods that grow in the wild. Some of these foods may contain natural materials that are poisonous to humans. In addition, some types of fish can be poisonous.

    Most people recover from food poisoning after a few days of resting and drinking extra water. If people eat natural poisons, they must go to the hospital right away to have their stomachs emptied.

    It has been described as art by some people, but to others it's an ugly part of modern life. What is it? Graffiti (涂鸦), of course. Look around cities in the UK today and you can see graffiti on buildings, walls, doors and even on buses or trains that have stayed in one place for too long. But where modern technology creates a problem, it also finds a way to deal with it. Last week, The Weekend West was shown around the factory of a small but successful company, Hubdean.

    Hubdean's achievement is a series of special paints which are graffiti-resistant. How do they work? It couldn't be simpler. Take any graffiti-covered surface. First, a treatment called Agproclear is used. Then, using a very hot pressure jet (压力喷嘴), this treatment is taken away and the graffiti disappears at the same time. Now you have a clean wall. But before this clean wall can be painted on by graffiti lovers, a new product, Agproshield, is used. This paint has a special surface which gives it two important advantages. Firstly, spray paint (喷雾颜料) won't stick to the surface very well, and secondly, the whole surface can be cleaned very easily, just using water. Once the surface is painted, no specialist equipment is needed to keep the area clean and graffiti-free.

    Not surprisingly, Hubdean's products are used by both local governments and private companies all over the UK, and now orders are being received from around the world. This brings the company a problem, however. Can they increase production to satisfy the needs? Of course, they can build a second factory or work with a large international company to make their products. The future is looking good for Hubdean!