Far from the land of Antarctica (南极洲), a huge shelf of ice meets the ocean. At the underside of the shelf there lives a small fish, the Antarctic cod.

    For forty years scientists have been curious about that fish. How does it live where most fish would freeze to death? It must have some secret. The Antarctic is not a comfortable place to work and research has been slow. Now it seems we have an answer.

    Research was begun by cutting holes in the ice and catching the fish. Scientists studied the fish's blood and measured its freezing point.

The fish were taken from seawater that had a temperature of -1.88℃ and many tiny pieces of ice floating in it. The blood of the fish did not begin to freeze until its temperature was lowered to

-2.05℃. That small difference is enough for the fish to live at the freezing temperature of the ice-salt mixture.

    The scientists' next research job was clear: Find out what in the fish's blood kept it from freezing. Their search led to some really strange thing made up of a protein (蛋白质) never before seen in the blood of a fish. When it was removed, the blood froze at seawater temperature. When it was put back, the blood again had its antifreeze quality and a lowered freezing point.

    Study showed that it is an unusual kind of protein. It has many small sugar molecules（分子）held in special positions within each big protein molecule. Because of its sugar content, it is called a glycoprotein. So it has come to be called the antifreeze fish glycoprotein, or AFGP.

    Being physically active three times a week reduces the odds of being depressed by about 16%, according to new UCL research carried out as part of the Public Health Research Centre.

    The study, published in JAMA Psychiatry, found a two-way relationship between depression and physical activity. People who increased their weekly activity were reported to have fewer depressive symptoms but those with more depressive symptoms were less active, particularly at younger ages.

    Researchers followed 11,135 people born in 1958 up until the age of 50, recording depressive symptoms and levels of physical activity at regular intervals in adulthood. They found that each additional activity period per week reduced odds of depression by 6%. In England 19% of men and 26% of women are currently classed as "inactive", and this study suggests that activity could significantly improve their mental as well as physical health.

    "Assuming the association is causal, physical activity has a protective effect against depression. If an adult between his twenties and forties who isn't physically active became active 3 times per week, he would reduce his risks of depression by about 16%," said Dr Snehal of the UCL Institute of Child Health, lead author of the study.

    Professor Mark，Director of the Public Health Research Centre, said: "Many people are already aware of the benefits of physical activity on their general health, but now we are seeing more evidence that suggests it also has a positive effect on a person's mental well-being. The latest research highlights just how important it is to ensure that people are working and living in environments that allow them to be both physically active and mentally healthy."

    Languages have been coming and going for thousands of years, but in recent times there has been less coming and a lot more going. When the world was still populated by hunter-gatherers , small tightly knit (联系) groups developed their own patterns of speech independent of each other. Some language experts believe that 10,000 years ago, when the world had just five to ten million people, they spoke perhaps 1,200 languages between them.

    Soon afterwards, many of those people started settling down to become farmers, and their languages too became more settled and fewer in number. In recent centuries, trade, industrialization, the development of the nation-state and the spread of universal compulsory education, especially globalization and better communications in the past few decades, all have caused many languages to disappear, and dominant languages such as English, Spanish and Chinese are increasingly taking over.

    At present, the world has about 6,800 languages. The distribution of these languages is hugely uneven. The general rule is that mild zones have relatively few languages, often spoken by many people, while hot, wet zones have lots, often spoken by small numbers. Europe has only around 200 languages; the Americas about 1,000; Africa 2,400; and Asia and the Pacific perhaps 3200, of which Papua New Guinea alone accounts for well over 800. The median number (中位数) of speakers is a mere 6,000, which means that half the world's languages are spoken by fewer people than that.

    Already well over 400 of the total of 6,800 languages are close to extinction (消亡), with only a few elderly speakers left. Pick, at random, Busum in Cameroon (eight remaining Speaker), Chiapaneco in Mexico (150), Lipan Apache in the United States (two or three) or Wadjigu in Australia (one, with a question-mark) none of these seems to have much chance of survival.

    Like many other people, I love my smart phone, which keeps me connected with the larger world that can go anywhere with me. I also love my laptop, because it holds all of my writing and thoughts. In spite of this love of technology, I know that there are times when I need to move away from these devices and truly communicate with others.

On occasion, I teach a course called History Matters for a group of higher education managers. My goals for the class include a full discussion of historical themes and ideas. Because I want students to thoroughly study the materials and exchange their ideas with each other in the classroom, I have a rule —no laptop, iPads, phones, etc. When students were told my rule in advance of the class, some of them were not happy.

    Most students assume that my reasons for this rule include unpleasant experiences in the past with students misusing technology. There's a bit of truth to that. Some students assume that I am anti-technology. There's no truth in that at all. I love technology and try to keep up with it, so I create to my students.

    The real reason why I ask students to leave technology at the door is that I think there are very few places in which we can have deep conversions and truly engage complex ideas. Interruptions by technology often break concentration and allow for too much dependence on outside information for ideas. I want students to dig deep within themselves for inspiration and ideas. I want them to push each other to think differently and make connections between the course materials and the class discussion.

    I've been teaching my history class in this way for many years and the evaluations reflect students' satisfaction with the environment that I create. Students realize that with deep conversation and challenge, they learn at a level that helps them keep the course materials beyond the classroom.

    I'm not saying that I won't ever change my mind about technology use in my history class, but until I hear a really good reason for the change, I'm sticking to my plan. A few hours of technology-free dialogue is just too sweet to give up.

    Everybody sleeps, but what people stay up late to catch or wake up early in order not to miss varies by culture.

    From data collected, it seems the things that cause us to lose the most sleep, on average, are sporting events, time changes, and holidays.

    Around the world, people change sleep patterns thanks to the start or end of daylight-saving time（夏令时间）. Russians, for example, began to wake up about a half-hour later each day after President Vladimir Putin shifted the country permanently to "winter time" starting on October 26.

    Russia's other late nights and early mornings generally correspond（相一致）to public holidays. On New Year's Eve, Russians have the world's latest bedtime, hitting the hay at around 3:30 a. m.

    Russians also get up an hour later on International Women's Day, the day for treating and celebrating female relatives.

    Similarly, Americans' late nights, late mornings, and longest sleep fall on three-day weekends.

    Canada got the least sleep of the year the night it beat Sweden in the Olympic hockey（冰球）final.

    The World Cup is also chiefly responsible for sleep deprivation. The worst night for sleep in the U. K. was the night of the England-Italy match on June 14. Brits stayed up a half-hour later to watch it, and then they woke up earlier than usual the next morning thanks to summer nights, the phenomenon in which the sun barely sets in northern countries in the summertime. That was nothing, though, compared to Germans, Italians, and the French, who stayed up around an hour and a half later on various days throughout the summer to watch the World Cup.

    It should be made clear that not everyone has a tool to record their sleep patterns; in some of these nations, it's likely that only the richest people do. And people who elect to track their sleep may try to get more sleep than the average person. Even if that's the case, the above findings are still striking. If the most health-conscious among us have such deep swings（明显改变）in our sleep levels throughout the year, how much sleep are the rest of us losing?

Tours to China

    Prices cover international airfares, departure taxes, fuel charges, local transportation, accommodation, all meals, entrance fees, guides, daily tours and visas for UK citizens. You may choose any route you enjoy most from the following:

Train Tour of Historic China—7 Days

    In this tour, you will visit Beijing, Luoyang and Xi'an, three ancient capital cities of China and take a full look at Chinese historical culture. Besides, the high-speed train journey will make this tour a fresh and memorable experience to you.

China Golden Triangle Tour—8 Days

    This tour includes Beijing's Forbidden City and the Great Wall. Afterwards, visit Xi'an, home to the famous army of Terracotta(赤陶) Warriors(武士). Your journey wraps up at Shanghai, China's most dynamic city.

Spirit of China—10 Days

    Your journey starts from Shanghai, China's most modern metropolis(大都市). Then visit elegant classic gardens and Grand Canal in Suzhou and the West Lake and taste the Dragon Well Tea in Hangzhou. Continue to Xi'an in Central China to admire the 6,000 life-sized Terracotta Warriors. The last destination of this memorable trip is Capital Beijing where to discover its timeless royal treasures.

China Highlights Tour with Yangtze Cruise(巡航)—11 Days

    This tour highlights a Yangtze River Cruise sailing through the Three Gorges. It also covers top cities in China, including imperial(帝国的)Beijing, Ancient Xi'an and modern Shanghai.

Tibet Tour—12 Days

    Tibet has always been a place of dream for many people. This tour will lend an impressive and unforgettable experience to you. As the highest and least polluted city in the world, Lhasa enjoys a status of "Mecca of Tibet". You will also visit the cities of Gyantse and Shigatse. The last stop of this tour is Xi'an.