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.

    Who could have imagined that a treadmill（跑步机）on wheels would one day become a thing?!? Lopifit is an unusual means of transportation that allows you to power an electric bicycle by walking on a treadmill.

Lopifit founder Bruin Bergmeester says it all started when he asked himself the question "How can I use a treadmill outdoors?" He finally came up with a new design, adding an electric motor, and the Lopifit was born. It's similar to an electric bicycle in that the motor only works when the rider puts power in as well. The Lopifit senses when you walk on the treadmill and uses the motor to turn a drive chain at the back of the treadmill, helping you reach a top speed of 17 miles per hour.

    To use the Lopifit, simply turn on the battery（电池）and use your foot to slide the treadmill backwards and start the motor. Then get on and enjoy the ride! If you need speed, just walk on the treadmill, and if you want to coast（惯性滑行）, all you have to do is stay still and admire the view. To stop, you have two hand breaks.

    The Lopifit first hit the streets in 2014 and, unsurprisingly, became a hit overnight. That was actually quite challenging for the company, because it started getting calls for orders, but it was nowhere near ready for mass production. The unique treadmill bicycle could be bought this year, and Lopifit is struggling to keep up with demand, although the price is up to $2,115.

    Some people consider this means of transportation stupid and unnecessary, although there is a very loyal fan-base of so-called Lopifitters. They simply believe that if you're going to walk, you might as well do it the old-fashioned way.

But the Lopifit does have the special advantage of helping you "walk" really fast without much effort, or walking at cycling speed, if you will.

    Like people, plants experience stress. And also, like people, the response to that stress can determine success.

    Bad environmental conditions, such as drought, flood, heat and other stresses, affect yields (产量) more than crop pests and diseases. We are trying to find a way to equip plants with the ability to tolerate environmental stress and maintain high yields, said Stephen Howell, a professor of genetics and cell biology.

    Plant cells produce proteins (蛋白质) and ship them to different parts of the cell. Under normal conditions, these proteins are folded into their normal, healthy structures as they are produced. When a plant is under stress, its cells produce poorly folded or unfolded proteins. Then a built-in system senses this and “sets off an alarm in the cell,” said Howell.

    In response to the alarm, another protein (IRE1) starts working and creates a different process which activates (激活) the stress response genes whose products bring about defensive measures that help the plant survive.

    “As it turns out, responses that are activated under stress conditions actually inhibit the growth of plants,” said Howell. “This allows them to preserve their energy to survive the stress conditions.”

    For plants in the wild, this response is a help for survival, he said. In production of agriculture crops, however, this response reduces yields.

    “You don't want crop plants to stop growing,” Howell said. “You want them to continue to grow and produce even though they are under stress.”

    With the new understanding of this stress response, the next step may be to silence the alarm system, said Howell. “What may be important is to disable some of these stress responses. That may make the plant more productive under stress conditions.”

    A Spanish company Siesta&Go has opened the first public napping (小睡) space in Madrid. It promises people a quiet rest in the middle of the city's business center.

    Napping spaces are nothing new; places to rest are already set up in other big cities in the world. But the idea would appear to work well with the culture of Spain, where people traditionally take an afternoon nap, called siesta.

    The Madrid nap space recently opened with 19 beds. People can use them by the minute or by the hour, and they can also choose either a private or shared room. An hour of napping inside a private room costs about $15.

    Siesta &Go provides all bedding, clean nightshirts and other materials. Nippers can request to be woken up when their time is up. It also offers areas to work, with armchairs, newspapers and coffee for those not wishing to sleep.

    Philip &Go is one happy customer. Marco says he gets tired during the day because of hard work. He says a siesta is the perfect way to build up energy. "I come for about 30 minutes or something like that. That is usually enough for me to be full of energy."

    While many Spanish people love their naps, others like Carlos Villarroja say they are just too busy to keep the tradition. "It's a Spanish tradition, but I think it's more of a legend (传说) than a tradition. Because of the lifestyle and the working hours, we have very little free time for a siesta at least during the week."

    But many health experts believe there is evidence that taking a short nap can be very good for the body and mind. Scientific studies show that taking a siesta can also prevent illness and lower blood pressure.

    Paris is the city of dreams. If you plan to head to Paris for a study period, then perhaps a little reality check is in order. But my experience was a romantic one.

    I paved my path to Paris through an exchange program. On arrival in Paris, I was constantly reminded of the official processes I had to complete — forms to be filled in, meetings to attend, the list seemed endless.

    Then the real work began. Once classes were underway, I found myself volunteering to do oral presentations and assignments first, rather than last. This method proved to be very helpful.

    Once I had finished class for the week, I had an ever-increasing list of museums to visit, neighborhoods to explore, and cafés to sit in. Read books about Paris. Talk to locals and other foreigners living there. But the one thing that reading a book or talking to someone cannot do is to provide you with the experience of wandering Paris on foot. The people watching, the sounds of the city, the colors as the seasons change, they all add to the ecstasy that I experience in Paris as an exchange student.

    After spending five months wandering through the charming neighborhoods, I fell in love with the atmosphere that came out from every open door, and with every spoken word. There is something comforting about walking to the market each Sunday to enjoy the beautiful display of fruits, vegetables and dairy products. There is warmth in saying bonjour to the passers-by.

    On my last day in Paris, I confidently said, "Bonjour Monsieur," as I passed the little store down the street. I guess the best part about going on exchange in Paris is falling in love with the city in your own way. And I know mine is unique and special to me, my own little pieces of Paris.

Economically speaking, are we better off than we were ten years ago? Twenty years ago?

In their thirst for evidence on this issue, commentators seized on the recent report by the Census Bureau, which found that average household income rose by 5.2% in 2015. Unfortunately, that conclusion puts too much weight on a useful, but flawed and incomplete, statistic. Among the more significant problems with the Census's measure are that: 1) it excludes taxes, transfers, and compensation like employer-provided health insurance; and 2) it is based on surveys rather than data. Even if precisely measured, income data exclude important determinants of economic wellbeing, such as the hours of work needed to earn that income.

While thinking about the question, we came across a recently published article by Charles Jones and Peter Klenow, which proposes an interesting new measure of economic welfare. While by no means perfect, it is considerably more comprehensive than average income, taking into account not only growth in consumption per person but also changes in working time, life expectancy, and inequality. Moreover, it can be used to assess economic performance both across countries and over time.

The Jones-Klenow method can be illustrated by a cross-country example. Suppose we want to compare the economic welfare of citizens of the U.S. and France in 2005.

In 2005, as the authors observe: real consumption per person in France was only 60% as high as the U.S., making it appear that Americans were economically much better off than the French on average. However, that comparison omits other relevant factors: leisure time, life expectancy, and economic inequality. The French take longer vacations and retire earlier, so typically work fewer hours; they enjoy a higher life expectancy, presumably reflecting advantages with respect to health care, diet, lifestyle, and the like; and income and consumption are somewhat more equally distributed there than in the U.S. Because of these differences, comparing France's consumption with the U.S.'s overstates the gap in economic welfare.

Similar calculations can be used to compare the U.S. and other countries. For example, this calculation puts economic welfare in the United Kingdom at 97 % of U.S. levels, but estimates Mexican well-being at 22%. The Jones-Klenow measure can also assess an economy's performance over time. According to this measure, as of the early-to-mid-2000s, the U.S. had the highest economic welfare of any large country. Since 2007, economic welfare in the U.S. has continued to improve. However, the pace of improvement has slowed markedly.

Methodologically, the lesson from the Jones-Klenow research is that economic welfare is multi-dimensional. Their approach is flexible enough that in principle other important quality-of-life changes could be incorporated—for example, decreases in total emissions of pollutants and declines in crime rates.