People who do not get enough vitamin A in their diet may develop night blindness. But in the developing world, a lack of vitamin A causes much more serious harm to children. The world Health Organization links the lack of vitamin A to as many as 250,000 child deaths every year.

    One excellent source of vitamin A is found in newly developed sweet potatoes with orange flesh. Orange sweet potatoes contain high levels of beta-carotene, which the body changes into vitamin A. Experts say orange sweet potatoes could help the Africans who are lacking in vitamin A. But, first, more people will need to be persuaded to eat them. Sweet potatoes need a better image in Africa. Jan Low with the International Potato Center says, “We do have an image problem with sweet potatoes. In many African countries, they are seen as a crop of the poor.”

    Ms. Low explains that sweet potatoes are mainly grown by poor women to feed their families in case another crop fails. The sweet potatoes commonly grown in Africa have white or yellow flesh. But they are low in vitamin A.

    Jan Low took part in a project to study how to market orange sweet potatoes to Africans best. She worked on an information campaign(活动) in Mozambique and Uganda. The campaign included radio messages about the nutritional(营养的) benefits of the orange sweet potato. They advertised its ability to “fight diseases, make you strong, clear you skin and make you look healthy”. In areas without radio, the campaigners spread the message through theater. The performances included singing, dancing and storytelling. And everywhere they went, the campaigners wore orange T-shirts and hats. They even drove orange cars.

    Dan Gustafson heads the Washington office of the United Nations Food and Agriculture Organization. He mentions the efforts in the past to increase the popularity of other nutritious crops. He says most of these efforts failed because organizers of the campaigns did not consider what people wanted to eat. People want to eat what they are familiar with. But Mr. Gustafson sees a better chance for the efforts to increase the popularity of the orange sweet potato in Africa. Except for the color, the orange sweet potato is almost the same as what people already eat. Dan Gustafson says, “I think this time the campaigners will succeed, because they have made enough advertisements and the difference between the vegetable they have advertised and what people already eat is not a radical one.”

    If you feel yourself turning into an old grouch(脾气坏的人), don't worry — happiness is just around the bend. A survey has found that although happiness dips in those in their 30s and 40s, people start to feel more content with life after the age of 50.

    However an economist found that older people will never again regain the excitement of youth. Rather it is thought that with age, individuals become more pragmatic about the ups and downs that life brings and accept their fortune.

    He questioned those in Britain, Switzerland and Germany and applied the findings to people's life cycle.

    Mr. Van Landeghem, 29, said:“A happiness curve does not necessarily imply that a 65-year-old prefers his own life to the life of a 25-year-old.”

    “Both the 25-year-old and 65-year-old might agree that it is nicer to be 25 than to be 65. But te 65-year-old might nevertheless be more satisfied, as he has learned to be satisfied with what he has.”

    It was suggested the mid-life happiness dip is because this is when people have the most responsibilities — taking care of a family, paying a mortgage (抵押贷款) and having a demanding career. The middle-aged dip in happiness was also compared to that of losing a close relative or suddenly becoming unemployed.

    The study is just one of many put forward as an indicator of what makes for a happy life.

    Psychologists concluded that having money makes you happier, but only if you have a lot more than your friends and neighbors. At the same time, you'd better have enough tie to enjoy yourself instead of spending all your time on making money.

    Separate research found that owning the house of your dreams, the car you always longed for and having millions in the bank doesn't stop that desire to keep up with the Joneses (攀比). And if the Joneses have more than you do, you'll be miserable. It seems envy at being lower in the social pecking order (权势等级) reduces the satisfaction of being well off.

    If you just do what you love and you are good at, which society also values much, you may have a higher probability to be happy. But if your job pays less, how can you stick to it in disregard of responsibilities? Happiness means different things from different points of view, and point of view grows from one's experience and knowledge. Perhaps it comes with you when you don't need to think about adult problems or when you are wise enough to understand what satisfaction is.

    Peter Skyllberg, a Swedish man, was trapped in his car for two months, with temperatures reaching -30^oC, with no food or water, and yet he survived. The best explanation was that his vehicle created an “igloo (snow house) effect” and protected him from the extremely low temperatures and that his body would hibernate(冬眠) during this time.

    Can humans get into a low-energy consumption state like a bear by reserving energy, and reducing body temperature? Chinese scientists are looking for the key to regulating body temperature.

    Scientists have found the hypothalamus (下丘脑), an area in the central lower part of the brain, is responsible for regulating body temperature. Wang Hong, a brain scientist at the Shenzhen Institutes of Advanced Technology of the Chinese Academy of Sciences, led her team to mark the neurons (神经元) responsible for regulating body temperature in mice by means of a cutting-edge genetic biology technique. In the experiments, they injected (注射) drug into mice to make the body temperatures of the mice drop rom 37℃ to 27 in two hours. The team found the change in body temperature caused no harm to the health of the mice. “We don't know if we can develop a drug that can control human body temperature. We still need a lot of study.” Wang said.

    Chinese scientists are not alone in such research. Body-cooling techniques are being used in pioneering hospitals around the world. Dutch doctors are now using low temperatures for patients who have suffered brain injuries in accidents, According to doctors working in Florence, it may even help to save the brains of babies who are born suffering from severe epileptic fits (癫痫病发作).

    London's newest skyscraper (摩天大楼) is called the Shard and it cost about 430 million pounds to build. At a height of almost 310 metres, it is the tallest building in Europe. The Shard has completely changed the appearance of London. However, not everyone thinks that it is a change for the better.

    The Shard was designed by the famous Italian architect Renzo Piano. When he began designing the Shard for London, Piano wanted a very tall building that looked like a spire (尖顶). He wanted the glass surfaces to reflect the sky and the city. The sides of the building aren't regular. So the building has an unusual shape. It looks like a very thin, sharp piece of broken glass. And that is how the building got the name: the Shard. Piano says that the spire shape of the Shard is part of a great London tradition. The shape reminds him of the spires of the churches of London or the tall masts (桅杆) of the ships that were once on the river Thames.

    The Shard has 87 floors. At the top, there is an observatory. At the moment the building is empty, but eventually there will be a five­star hotel. There will also be top quality restaurants, apartments and offices.

    Before building work began, a lot of people didn't want the Shard though the plans were approved. Now they are still unhappy about the Shard. Some critics say that such a tall skyscraper might be good in a city like New York, but not in London. They say that the best thing about the Shard is its spire shape. But that is the only thing. There is no decoration, only flat surfaces. The Egyptians did that 4, 500 years ago. They also think the Shard is too big for London. It destroys the beauty of the city.

    Other critics don't like what the Shard seems to represent. They say that the Shard shows how London is becoming more unequal. Only very rich people can afford to buy the expensive private apartments and stay in the hotel. But the people who live near the Shard are among the poorest in London. So the Shard seems a symbol of the division in society between the very rich and the poor.

    The Shard now dominates the London skyline. It is not certain, however, that ordinary London citizens will ever accept it as a valuable addition to the city.

    More and more people like bicycling and it is no surprise. It is fun, healthy and good for the environment.

    Maybe that's why there are 1.4 billion bicycles and only 400 million cars on roads worldwide today. Bikes can take you almost anywhere, and there is no oil cost! Get on a bicycle and ride around your neighborhood. You may discover something new all around you. Stopping and getting off a bike is easier than stopping and getting out of your car. You can bike to work and benefit(受益)from the enjoyable without polluting the environment. You don't even have to ride all the way.

    Folding(折叠) bikes work well for people who ride the train. Just fold the bike and take it with you. You can do the same on an airplane. A folding bike can be packed in a suitcase. You can also take a common bike with you when you fly. But be sure to look for information by getting on airline websites. Not all airlines are bicycle-friendly to travelers.

    Health benefits of bicycling

    It helps to prevent heart diseases

    Bicycling helps to control your weight

    A 15-minute bike ride to and from work three times a week burns off five kilos of fat in a year.

    Bicycling can improve your mood.

    Exercise like bicycling has been shown to make people feel better, more relaxed and self-confident.

Macquarie Island is a tiny island that's part of Australia. It's about halfway between New Zealand and Antarctica. The island's been made a world heritage area because it's so untouched, but this unique environment is under threat from some unwanted visitors.

It all started when seal hunters came to the island in the early 1800s. They brought rabbits with them as a source of food for the journey, and also on board the ships were rats and mice, which made their way onto the island too. They're being blamed for destroying the homes of marine birds, causing soil loss and ripping up plant cover, as these before-and-after photos show.

So what's being done about the problem? It starts with a team of helicopters that fly across the island carrying these giant containers. Inside them are poisoned pellets (有毒饲料) which are dropped and spread across the island. For any rabbits that survived the baiting (诱饵) , there's a plan B. This special team of dogs is being put through a final training. It'll be their job to track down any remaining rabbits. They have to also learn to behave around the island's native wildlife. The dogs could be here for years or until the task is complete. The dogs don't actually kill the rabbits. They find them, then the hunters decide to either catch the rabbits or shoot them.

But the program has received a bit of criticism. Some people argue 25 million dollars is a lot of money to be spending on wiping out rabbits and rodents (啮齿目动物), and in the process, some native birds will be killed because of the baiting. 

The reality is the problem isn't going to be solved overnight. The people running the program say that even if one pair of rabbits is left alive, the whole task will be seen as a failure, which means these guys could be here for a long time, trying to ensure that this precious island remains protected from pests.