Stephen Hawking, the brilliant British theoretical physicist who published wildly popular books exploring the mysteries of the universe, has died, according to a family spokesman. He was 76.

    Considered by many to be the world's greatest living scientist, Hawking was also a cosmologist, astronomer, mathematician and author of numerous books including the landmark“A Brief History of Time,” which has sold more than 10 million copies.

    With fellow physicist Roger Penrose, Hawking combined Einstein's theory of relativity with quantum theory(量子理论) to suggest that space and time would begin with the Big Bang and end in black holes. He also discovered that black holes were not completely black but emit(释放) radiation and would likely eventually evaporate(蒸发) and disappear. “It will be difficult enough to avoid disasters on planet Earth in the next 100 years, let alone next thousand, or million. The human race shouldn't have all its eggs in one basket or on one plant. Let's hope we can avoid dropping the basket until we have spread the load.”

    Hawking suffered from ALS (amyotrophic latcral sclerosis), a disease which is usually fatal within a few years. He was diagnosed in 1963, when he was 21, and doctors initially gave him only a few years to live. The disease left Hawking wheelchair-bound and paralyzed. He was able to move only a few fingers on one hand and was completely dependent on others or on technology for everything—bathing, dressing, eating, even speech. “I have been lucky that my condition has progressed more slowly than is often the case. But it shows that one need not lose hope.” Dramatically, he even guest-starred in the “Star Trek”, “The Simpsons” and the 2014movie “The theory of Everything”.

    Hawking leaves behind three children and three grandchildren. “We are deeply saddened that our beloved father passed away today,” Hawking's children, Lucy, Robert and Tim, said in a statement. “He was a great scientist and an extraordinary man whose work and legacy will live on for many years. His courage and persistence with his brilliance and humor inspired people across the world. “We will miss him forever.”

    “Freelance retail consultant” refers to daigou in Chinese, or overseas people who buy goods for customers in the Chinese mainland.

     It's estimated that there are 40,000 daigou in Australia, most of whom are young migrants or international students looking for ways to help cover their rent and university cost.

    These freelance retail consultants have created thousands of trading routes, both small and big, into China.

    Shops in Australia sold out of instant formula （婴儿配方奶粉）, leaving many Australian parents unable to buy their preferred brands. The Sydney Morning Herald reported last year that half of Australia's infant formula sold went to China through customers selling to other customers.

    Because of this, daigou have received criticism from Australian media. The Sydney Morning Post even suggested that the Australian government should put a limit on instant formula exports.

    However, not everyone dislikes daigou. “We think daigou are good for the local economy and they are very good for our business,” Peter Nathan, the chief executive of A2 Milk, a New Zealand infant formula maker, told Reuters. “We clearly believe they are a positive force.”

    Others agree that nothing is wrong with the practice. “People are buying these products legally on the Australian market… they're not illegally being exported to China,” Tim Foulds, head of research at Euro monitor Australia and New Zealand, told The Washington Post.

                                                                                           Taktak tabulaba?

    You probably don't know how to answer that question ─ unless you happen to be one of the about 430 people in the world who speak a language called Matukar Panau. Then you would know it means “ What are we doing?” Matukar Panau is one of the world's rarest languages. It is spoken in just two small coastal villages in Papua New Guinea.

    Several years ago, David Harrison, a language expert, didn't know much about Matukar Panau either. No one had ever recorded or even studied its words and rules. With so few speakers, the language risked disappearing soon. It was endangered.

    Harrison didn't want that to happen to Matukar Panau. So in 2009, he set out for Papua New Guinea. His goal: use modern technology to help the remaining speakers preserve their native tongue.

    But Matukar Panau is not the only language facing loss. Studies suggest that by the end of this century，nearly half of the 7,000 languages now spoken worldwide could disappear. They're in danger partly because the only people left speaking them are elderly adults. When those old men die, their language will die with them. In addition, children may discard a native language and instead use more common global languages, such as Chinese, English or Spanish.

    In the United States alone, 134 native American languages are endangered. “Language hotspots” exist all over the world. These are places with endangered languages that haven't been recorded. They include the state of Oklahoma, pockets of central and eastern Siberia, parts of northern Australia and communities in South America.

    Reading may be fundamental, but how the brain gives meaning to letters on a page has been a mystery. Two new studies fill in some details on how the brains of efficient readers handle words. One of the studies, published in the April 30 Neuron, suggests that a visual-processing area of the brain recognizes common words as whole units. Another study, published online April 27 in PLOSONE, makes it known that the brain operates two fast parallel systems for reading, linking visual recognition of words to speech.

    Maximilian Riesenhuber, a neuroscientist at Georgetown University in Washington, D. C. , wanted to know whether the brain reads words letter by letter or recognizes words as whole objects. He and his colleagues showed sets of real words or nonsense(无意义的词语)words to volunteers undergoing FMRI scans. The words differed in only one letter, such as “farm” and “form” or “soat” and “poat”, or were completely different, such as “farm” and “coat”or “poat” and “hime”.The researchers were particularly interested in what happens in the visual word form area, or VWFA, an area on the left side of the brain just behind the ear that is involved in recognizing words.

    Riesenhuber and his colleagues found that neurons(神经元)in the VWFA respond strongly to changes in real words. Changing “farm” to “form”, for example, produced as great a change in activity as changing “farm” to“coat”, the team reports in Neuron. The area responded slowly to single-letter changes in made-up words.

    The data suggests that readers grasp real words as whole objects, rather than focusing on letters or letter combinations. And as a reader's exposure to a word increases, the brain comes to recognize the shape of the word. “Meaning is passed on after recognition in the brain”, Riesenhuber says.

    The researchers don't yet know how longer and less familiar words are recognized, or if the brain can be trained to recognize nonsense words as a unit.

    Banff National Park is Canada's first national park. In 1883, on the Canadian Rocky Mountains, three railway workers discovered a natural hot spring, and from there the park was born. Nowadays, it is one of the world's popular tourist spots with great mountain scenery. Every year, millions of people visit it for its wonderful views.

Banff National Park is part of UNESCO's Canadian Rocky Mountain World Heritage site. Located in the heart of the Canadian Rockies, the park has perfect mountains like those on postcards. They are from 45 to 120 million years old, with the highest in the park, Mount Forbes, coming in at 11,850 feet.

    Banff National Park is 80 miles west of Calgary. Calgary's international airport is serviced by major national and international carriers with many flights arriving daily. Open year­round, it offers amazing wildlife viewing and sightseeing, plus many shopping and dining choices, any time of the year. Summer is popular for hiking, mountain biking and cycling, photography, and climbing. The best time for viewing the seasonal color is fall, when the trees turn yellow.

    In winter, the mountain makes exciting downhill (速降) and cross­country skiing. In fact, three major downhill ski resorts (度假胜地) operate within the park. Lake Louise Ski Resort, Sunshine Village, and Mount Norquay combine to offer a large area for skiing, not to mention the backcountry trails available throughout the park. The ski season, which runs from November to May, is one of the longest in North America. Visitors can also enjoy wildlife tours, ice walks, and dogsleds (雪橇).

    Weather in the Canadian Rockies can change quickly. A single day can have a mix of sunshine, snow, wind, and rain, so you should change your clothes. In summer, temperatures average a high of 70 (21 ℃), and daylight lasts until 11 p. m. Autumn brings cool nights and fresh air. Winters can be very cold. In January, the average temperature is 7 ℃ below zero, but by April it is 9 ℃.

Richard Holmes, a British author and academic, is something of a Romantic, famous for biographies of Percy Bysshe Shelley and Samuel Taylor Coleridge. In his last book, "The Age of Wonder", he wrote about science and Romanticism and their common commitment to discovery. In his new book, "Falling Upwards", he combines the two again to tell the stories of Europe's early balloonists (气球飞行者).

Mr Holmes's love of balloons was aroused at a village festival and his enthusiasm is one of the book's many pleasures. He refers to the cheerful tone used in many first-hand ballooning stories, and applies it in this second-hand account. He describes men and women wrapped up in fur coats under their hydrogen-filled balloons, enjoying cold chicken and champagne and looking back to earth to see mankind "for what it really is."

Mr Holmes makes much of the strange side of ballooning, but the book is at its best when examining its more serious applications. In the American civil war, for example, both North and South put observers in balloons to spy on enemy movements. And during the Prussian attack on Paris in 1870-71， balloonists managed to fly out of the city to communicate with the French government in exile (流亡) in Tours.

"Falling Upwards" contains much of the historian's writing characteristics, such as footnotes and bibliography (文献书目), but its epilogue (后记) refers modestly to what has gone before as "a series of true balloon stories". It does touch on the more technical aspects of ballooning, and says little about the French Montgolfier brothers who are credited as its inventors. That though seems a small price to pay for such a spirited work. Mr Holmes's tale ends at the start of the 20th century when the business of flight was being handed over to the airship and the airplane.