What will power your house in the future？Nuclear, wind, or solar power？According toscientists at the Massachusetts Institute of Technology(MIT)in the US, it might beleaves—but artificial(人造的)ones.

    Natural leaves are able to change sunlight and water intoenergy. It is known as photosynthesis(光合作用). Nowresearchers have found a way to imitate this seemingly simple process.

    The artificial leaf developed by Daniel Nocera and hiscolleagues at MIT can be seen as a special silicon chip with catalysts(催化剂). Similar tonatural leaves, it can splitwater into hydrogen and oxygen when put into a bucket of water. The hydrogenand oxygen gases are then stored in a fuel cell, which usesthose two materials to produce electricity, located eitheron top of a house or beside the house.

Though the leaf is only about the shape of a poker card, scientistsclaimed that it is promising to be an inexpensive source of electricity indeveloping countries.“ One can imagine villages in India and Africa not longfrom now purchasing an affordable basic power system based on this technology, ”said Noceraat a conference of the American Chemical Society.

    The artificial leaf is not a new idea. The first artificial leafwas invented in 1997 but was too expensive and unstable for practical use. Thenew leaf, by contrast, is made ofcheap materials, easy to useand highly stable. In laboratory studies, Nocera showedthat an artificial leaf prototype(原型)could operatecontinuously for at least 45 hours without a drop in activity.

    The wonderful improvements come from Nocera's recent discoveryof several powerful, new andinexpensive catalysts. These catalysts make the energy transformation insidethe leaf more efficient with water and sunlight. Right now, the new leafis about 10 times more efficient at carrying out photosynthesis than a naturalone. Besides, the device canrun in whatever water is available；that is, it doesn'tneed pure water. This is important for some countries that don't have access topure water.

    With the goal to “make each home its own power station” and“give energy to the poor”, scientistsbelieve that the new technology could be widely used in developing countries, especially inIndia and rural China.

    The U. S. Postal Service (USPS) is losing billions of dollars a year. The government company that delivers "small mail" is losing out to email and other types of electronic communication. First-class mail amount fell from a high point of 104 million pieces in 2000 to just 64 million pieces by 2014.

    Congress permits the 600.000-empIoyee USPS to hold a monopoly (垄断) over first-class and standard mail. The company pays no federal, state or local taxes; pays no vehicle fees; and is free from many regulations on other businesses. Despite these advantages, the USPS has lost $52 billion since 2007, and will continue losing money without major reforms.

    The problem is that Congress is preventing the USPS from reducing costs as its sales decline, and is blocking efforts to end Saturday service and close unneeded post office locations. USPS also has a costly union-dominated workforce that slows the introduction of new ideas or methods down. USPS workers earn significantly higher payment than comparable private-sector workers. The answer is to privatize the USPS and open postal markets to competition. With the rise of the Internet, the argument that mail is a natural monopoly that needs government protection is weaker than ever.

    Other countries facing declining letter amounts have made reforms Germany and the Netherlands privatized their national postal companies over a decade ago, and other European countries have followed suit. Britain floated shares of the Royal Mail on its stock exchange in 2013. Some countries, such us Sweden and New Zealand, have not privatized their national postal companies, but they have opened them up to competition.

    These reforms have driven efficiency improvements in all of these countries. Additional number of workers have been reduced, productivity has risen and consumers have benefited. Also, note that cost-cutting measures—such as closing tone post offices—are good for both the economy and the environment.

    Privatization and competition also encourage new changes. When the USPS monopoly over "extremely urgent" mail was stopped in 1979, we saw an explosion in efficient overnight private delivery by firms such as FedEx.

    The government needs to wake up to changing technology, study postal reforms abroad and let businessmen reinvent our out-of-date postal system.

    He wishes the holiday season would end already. His back aches, his red suit feels like a spacesuit, his cheeks have gone tight from smiling for 12 hours—and still the kids keep coming and coming, like ants at a picnic. As Christmas becomes more commercialized (商业化) across the U. S. and Canada, so must Santa Claus. As the holiday begins earlier each year, so must its spokesmen.

    The questions from children these days are harder than ever. Now, with thousands of children expecting a father or mother serving in Iraq or Afghanistan, the questions are as heart­breaking as they are unanswerable. For example, “Can you please bring Daddy home from the war in time for Christmas morning？”

    Santa Claus; also have a pretty good chance of getting sued (指控). A professional Santa Claus in Canada told a story: A Santa had a girl on his knee, and he commented, “You have nice eyes and nice hair.” The girl later said it was sexual harassment (骚扰). When a Santa feels anxious, he often shows it in the same ways ordinary people do. The Santa Claus were always seen to hang around at the dinner table when the show ended. Many of them just sleep in bed for several days and don't see other children again.

    Washington, D.C. Bicycle Tours

    Cherry Blossom Bike Tour in Washington, D.C.

    Duration: 3 hours

    This small group bike tour is a fantastic way to see a world-famous cherry trees with beautiful flowers of Washington, D.C. Your guide will provide a history lesson about the trees and the famous monuments where they blossom. Reserve your spot before availability — the cherry blossoms—disappear!

    Washington Capital Monuments Bicycle Tour

    Duration:3 hours (4 miles)

    Join a guided bike tour and view some of the most popular monuments in Washington, D.C. Explore the monuments and memorials on the National Mall as your guide shares unique facts and history at each stop. Guided tour includes bike, helmet, cookies and bottled water.

Capital City Bike Tour In Washington, D.C.

    Duration:3 hours

    Morning or Afternoon, this bike tour is the perfect tour for D. C. newcomers and locals looking to experience Washington, D.C. in a healthy way with minimum effort. Knowledgeable guides will entertain you with the most, interesting stories about Presidents, Congress, memorials, and parks. Comfortable bikes and a smooth tour route(路线）make cycling between the sites fun and relaxing.

Washington Capital Sites at Night Bicycle Tour

    Duration:3 hours (7 miles)

    Join a small group bike tour for an evening of exploration in the heart of Washington, D.C. Get up close to the monuments and memorials as your bike the sites of Capitol Hill and the National Mall. Frequent stops are made for photo taking as your guide offers unique facts and history. Tour includes bike, helmet, and bottled water. All riders are equipped with reflective vests and safety lights.

    A five-year-old dog named Kelsey has been praised as a hero for helping to save the life of her owner who slipped in the snow and broke his neck.

    The man, Bob, was alone when he left his Michigan farmhouse on New Year's Eve to collect firewood. Expecting a journey of only several meters, Bob was wearing just long johns (衬裤), a shirt and slippers when he went outside, although the temperature was around -4℃.

    After the accident, he was unable to move in the snow. Fortunately, Kelsey came to his assistance.

    "I was shouting for help, but my nearest neighbor is about 400 meters away, and it was 10:30 pm, Bob explained." But my Kelsey came. By the next morning, my voice was gone and I couldn't yell for help, but Kelsey didn't stop barking."

    Kelsey's companion kept him warm by lying on top of him. She licked his face and hands to keep him awake." Kelsey kept barking but never left my side," Bob recalled. "She kept me warm. I knew I couldn't give up and that it was my choice to stay alive."

    Bob spent 20 hours in the freezing cold. When he finally lost consciousness, his dog kept barking. Finally, hearing the barking, Bob's neighbor discovered him at 6:30 pm on New Year's Day and called the emergency services at once. When Bob arrived in hospital, his body temperature was below 21℃. However, doctors were surprised to find that he didn't have any frostbite (冻疮). They believed it was because of Kelsey's determination to keep him warm, Dr. Chaim Colen, the doctor who treated Bob, said, "Animals can help and his dog really saved him... He was very fortunate.”

    Bob said he was "enormously" grateful to both Dr. Colen and his Kelsey, "They saved my life. They are truly heroes!"

    In many developed countries, people who have high degrees begin to work longer than those who don't. About 65% of American men aged 62－74 with a professional degree are in the workforce (劳动人口), compared with 32% of men who only finish high school. This gap is part of a deepening divide between the well-educated wealthy and the unskilled poor. Rapid technological advance has raised the incomes of the highly skilled while squeezing those of the unskilled. The consequences, for individuals and society, are profound (意义深远的).

    The world is facing an astonishing rise in the number of old people, and they will live longer than ever before. Over the next 20 years the global population of those aged 65 or more will almost double, from 600 million to 1.1 billion. The experience of the 20th century, when greater longevity (长寿) translated into more years in retirement rather than more years at work, has persuaded many observers that this shift (变化) will lead to slower economic growth, while the swelling (渐增的) ranks of pensioners will create government budget problems.

    Policies are partly responsible. Many European governments have abandoned policies that used to encourage people to retire early. Even the better-off must work longer to have a comfortable retirement. But the changing nature of work also plays a big role. Pay has risen sharply for the highly educated, and those people continue to reap (获得) rich rewards into old age because these days the educated elderly are more productive than the preceding (先前的) generation. Technological change may well reinforce (强化) that shift: the skills that complement (补充) computers, from management know-how to creativity, do not necessarily decline with age.