The streams are about 12 to 15 feet wide and 300 feet or more long, scientists said. "What we're dealing with is wet soil, thin layers of wet soil, not standing water," said Aifred  McEwen of the University of Arizona at Tueson! the principal scientist for the Mars Reconnaissance Orbiter's high-resolution imaging experiment,

     Because liquid water is essential to life, the findings could have major implications for the possibility of Martianlife, There searchers said further exploration is needed to determine whether microscopic life exists on the planet.

    The presence of liquid water could also make life easier for astronauts visiting or living on Mars. Watercould be used for drinking and for creating oxygen and rocket fuel. NASA's goal is to send humans there inthe 2030s.

    The evidence of flowing water consistslargely of dark, narrow streaks(条痕) on the surface that tend to appear and growd uring the warmest Martian months and fade the rest of the year.

    Mars is extremely cold even in summer,and the streaks are in places where the temperature is as low as minus 10 degrees Fahrenheit. But salt can lower the freezing point of water and melt ice.

    The source of the water is a mystery. Scientists noted it could be melting ice. It could be an underground a quifer, which is rock or sand that can hold water. It is possibly water vapor from the thin Martian atmosphere, Or it may be a combination Michael Meyer, lead scientistfor NASA's Mars exploration program, said the only definitive way for now to determine whether there's life on Mars is to collect rocks and soil foranalysis on Earth - something a U.S. lander set for lift-off in 2020 will do.

C

    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 12,000 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, industrialisation, the development of the nation-state and the spread of universal compulsory education, especially globalisation 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 3,200, 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, Busuu in Cameroon (eight remaining speakers), 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.

    My professor brother and I have an argument about head and heart, about whether he overvalues IQ while I lean more toward EQ. We commonly have this debate about people—can you be friends with a really smart jerk（怪物）?—but that also applies to animals as well .I'd love it if our dog could fetch the morning paper and then read it to me over coffee, but I actually care much more about her loyal and innocent heart. There's already enough thinking going on in our house, and we probably spend too much time in our heads. Where we need some role modeling is in instinct, and that's where a dog is a vivid example.

    I did not grow up with dogs, which meant that my older daughter's respectful but firm determination to get one required some adjustment on my part. I often felt she was training me: from ages of 6 to 9, she gently schooled me in various breeds and their personalities, whispered to the dogs we met with so they would charm and persuade me, demonstrated by her self-discipline that she was ready for the responsibility. And thus came our dog Twist, whom I sometimes mistake for a third daughter.

    At first I thought the challenge would be to train her to sit, to follow, to walk calmly beside us and not go wildly chasing the neighborhood rabbits. But I soon discovered how much more we had to learn from her than she from us.

    If it is true, for example, that the secret to a child's success is less rare genius than raw persistence, Twist's ability to stay on task is a model for us all, especially if the task is trying to capture the sunbeam that touches softly around the living room as the wind blows through the branches outside. She never succeeds, and she never gives up. This includes when she runs straight into walls.

    Then there is her unfailing patience, which breaks down only when she senses that dinnertime was 15 minutes ago and we have somehow failed to notice. Even then she is more eager than annoyed, and her refusal to complain shows a self control of which I'm not always capable when hungry.

    But the lesson I value most is the one in forgiveness, and Twist first offered this when she was still very young. When she was about 7 months old, we took her to the vet to be spayed（切除卵巢）. We turned her over to a stranger, who was to perform a procedure that was probably not pleasant. But when the vet returned her to us, weak and tender, there was no accusation, no how could you do that to me? It was as though she already knew that we would not intentionally cause her pain, and while she did not understand, she forgave and curled up with her head on my daughter's lap.

    I suppose we could have concluded that she was just blindly loyal and obedient. But eventually we knew better. She is entirely capable of disobedience, as she has proved many times. She will ignore us when there are more interesting things to look at, scold us when we are careless, bark into the twilight when she has urgent messages to send. But her patience with our failings and carelessness and her willingness to give us a second chance are a daily lesson in gratitude.

    My friends who grow up with dogs tell me how when they were teenagers and trusted no one in the world, they could tell their dog all their secrets. It was the one friend who would not gossip or betray, could provide in the middle of the night the soft, unselfish comfort and peace that adolescence plots to disturb. An age that is all about growth and risk needs some anchors and weights, a stable model when all else is changing. Sometimes I think Twist's devotion keeps my girls on a benevolent leash, one that hangs quietly at their side as they walk fast along but occasionally pulls them back to safety and solid ground.

We've weighed so many decisions so carefully in raising our daughters—what school to send them to and what church to attend, when to give them cell phones and with what precautions. But when it comes to what really shapes their character and binds our family, I never would have thought we would owe so much to its smallest member.

    Nancy Ballard, 60, went for a routine checkup that turned into something extraordinary. She had just completed her master's in botanical illustration. In fact, she was canting a painting of a plant she'd done when she arrived at her doctor's San Francisco office. “It would be great if we had artwork like that for our chemotherapy(化疗)rooms, ”the nurse said. Ballard asked to see one.

    She was shocked by what she found. The walls were bare, and the paint was chipping(剥落).She could tell where old artwork had hung because of the naked nails. It was a depressing room for a depressing routine—patients had chemo drips for perhaps several hours, often with nothing to look at other than those sad walls. She couldn't imagine how anyone could even think about getting healthy in a room like that. As it happened, Ballard's physician, Stephen Hufford was ill with cancer himself, so finding time to decorate the rooms was low on his to-do list. So Ballard made it her mission to brighten up the place.

    She wrote to 20 local interior designers and asked whether they would donate their time and money to transform just one of Dr. Hufford's rooms each. Six of them wrote back almost immediately. Each of them ultimately chose a theme: The dragonfly room, for example, now features bright artwork and dragonfly wall ornaments. Most rooms got new paint, light fixtures, artwork, and furniture. Each room cost about $5, 000.

    Dr. Hufford was delighted.“ All the patients feel soothed by it.” he noted. He even said that his own tone of voice was different in the rooms and that he was better able to connect with his patients.

    Ballard was so encouraged that she created a nonprofit to raise money and decorate more spaces. Since then, she has worked on 20 projects, including one in Pennsylvania. She once went to Philadelphia for a ribbon cutting, and a woman there was on her third battle with cancer. When she saw what Ballard had done, she said, “I'm gonna beat it this time.I thought I wasn't going to, but now I know I'm gonna beat it.”

    Bike sharing have become popular words in cities from Cape Town to Shanghai to Melbourne. Planners, politicians and media keep showing off their benefits: reducing pollution, congestion, travel costs and oil dependence, while improving public health. Bike sharing also helps make cities appear modern, dynamic and worldwide--qualities much sought after by the creative class.

    But what makes for a successful public bike-sharing program? This is an important question because installing one requires significant public and private investment and adjustment to the built environment.

    While many programs have been launched among much praise, often their popularity has soon declined. Many end up operating at a financial loss and depend on other profitable enterprises to cross-subsidize (交叉补贴) them. Some have resulted in thrown-away bikes becoming an eyesore.

    Understanding which factors enhance or stop public bike sharing is critical in helping cities decide whether such a program is workable, before considering what design and sitting will work best.

    Drawing on current knowledge, we discuss the importance of the local landscape, climate, cycling infrastructure (基础设施) and land use. We also touch on other factors, such as the legal environment and the characteristics of the bike-sharing program itself.

    Take natural environment for example. Two natural environment factors are known to affect participation: hilliness and weather. Hilliness discourages balanced bike-sharing use, as users avoid returning bicycles to stations on hilltops. Those stations end up being empty, while stations on flat areas are often full, so users cannot find a station to return their bikes.

    As for weather, ideal temperature ranges vary by the climate zone. Case studies show warm and dry weather encourages public bike-sharing use. Rain and strong wind reduce the frequency of trips. However, some approaches, such as providing sheltered, shaded, or even heated or cooled cycling infrastructure, could prove useful.

Narayana Peesapaty was sitting on a flight when he noticed a passenger trying to reach food with a biscuit after breaking his spoon. At that moment, the researcher's mind gave birth to a simple yet revolutionary concept — edible spoons.

How do you like your spoon?

Peesapaty's company, Bakeys, makes edible spoons mainly out of sorghum(高粱）though rice, wheat and water are also ingredients. They combine to form a dry eating tool that remains hard even when used in moist or hot foods. Bakeys also makes ginger and garlic flavored(风味) spoons to meet specific requests. All spoons are completely natural and acceptable for nearly all diets.

A rice replacement

An environmentally-minded water researcher, Peesapaty, designed his spoons to be eco-friendly in several ways. Sorghum was chosen as the main ingredient of the spoons instead of rice, which requires 60 times as much water. Sorghum was also chosen for the strength it would lend eating tool, and the grain requires little water, low energy and no chemicals to grow.

In place of plastic

The goal that Peesapaty hopes to attain through Bakeys is to prevent plastic from any contact with food. Plastic products can contain cancer-causing substances that come into food, and average plastic bottles take 450 years to break down. In contrast, a Bakeys' spoon is nutritious and break down in 10 days or less if thrown away. Peesapaty admits that using plastic is cheaper, but he also says that his spoons will be equally inexpensive when mass-produced.