If humans were truly at home under the light of the moon and stars, we would go in darkness happily, the midnight world as visible to us as it is to the vast number of nocturnal(夜间活动的) species on this planet. Instead, we are diurnal creatures, with eyes adapted to living in the sun's light. This is a basic evolutionary fact, even though most of us don't think of ourselves as diurnal beings. Yet it's the only way to explain what we've done to the night: We've engineered it to  receive us by filling it with light.

    The benefits of this kind of engineering come with consequences 一 called light pollution 一 whose effects scientists are only now beginning to study. Light pollution is largely the result of bad  lighting design, which allows artificial light to shine outward and upward into the sky. III-designed lighting washes out the darkness of night and completely changes the light levels 一 and light  rhythms — to which many forms of life, including, ourselves, have adapted. Wherever human light spills into the natural world, some aspect or life is affected.

    In most cities the sky looks as though it has been emptied of stars, leaving behind a vacant haze(霾) that mirrors our fear of the dark. We've grown so used to this orange haze that the original glory of an unlit nigh, - dark enough for the planet Venus to throw shadow on Earth, is wholly beyond our experience, beyond memory almost.

    We've lit up the night as if it were an unoccupied country, when nothing could be further form the truth. Among mammals alone, the number of nocturnal species is astonishing, Light is a powerful biological force, and on many species it acts as a magnet(磁铁). The effect is so powerful that scientists speak of songbirds and seabirds being “captured” by searchlights on land or by the light from gas flares on marine oil platforms. Migrating at night, birds tend to collide with brightly lit tall buildings.

    Frogs living near brightly lit highways suffer nocturnal light levels that are as much as a million times righter than normal, throwing nearly every aspect of their behavior out of joint including most other creatures ,we do need darkness. Darkness is as essential to our biological welfare, to our internal clockwork, as light itself.

    Living in a glare of our making,we have cut ourselves off from our evolutionary and cultural heritage—the light of the stars and the rhythms of day and night .In a very real sense light pollution causes us to lose sight of our true place in the universe, to forget the scale of our being, which is best measured against the dimensions of a deep night with the Milky Way—the edge of our galaxy arching overhead.

    An absolute description of the threat hanging over the world's mammals,reptiles,amphibians and other life forms has been published by the well-known scientific journal,Nature.A special analysis carried out by the journal indicates that an astonishing 41% of all amphibians on the planet now face extinction while 26% of mammal species and 13% of birds are similarly threatened.

    Many species are already critically endangered and close to extinction,including the Sumatran elephant,Amur leopard and mountain gorilla.But also in danger of vanishing（消失）for the wild,it now appears,are animals that are currently rated as merely being endangered.

    In each case,the finger of blame points directly at human activities.The continuing spread of agriculture is destroying millions of hectares of wild habitats every year,leaving animals without homes,while the introduction of newly-come species,often helped by humans,is also damaging native populations.At the same time,pollution and overfishing are destroying ocean ecosystems.

    "Habitat destruction,pollution or overfishing either kill off wild creatures and plants or leaves them badly weakened," said Derek Tittensor,an ocean ecologist at the World Conservation Monitoring Centre in Cambridge. "The trouble is that in coming decades,the additional threat of worsening climate change will become more and more common and could then kill off these survivors."

    The problem,according to Nature,is worsened because of the huge gaps in scientists knowledge about the planet's biodiversity.Evaluations of the total number of species of animals and plants alive vary from 2 million to 50 million.In addition,evaluations of current rates of species' disappearances vary from 500 to 36,000 a year. "That is the real problem we face," added Tittensor. "The scale of uncertainty is huge."

    In the end,however,the data indicate that the world is heading cruelly towards a mass extinction-which is defined as one involving a loss of 75% of species or more.This could arrive in less than a hundred years or could take a thousand,depending on extinction rates.

    When people today talk about a tiny house, they probably mean the trendy living space that's about the size of a shed (棚). But you would have to be five inches tall to live in the original tiny houses. Dollhouse(小房子)，which have been around for several centuries, don't offer shelter to real people, but they provide a vivid（生动的） experience of life in times and places both real and imaginary.

    The National Building Museum in Washington, D.C., lets visitors time travel in this tiny world through ―Small Stories: At Home in a Dollhouse,” an exhibit that opened Saturday. Visitors can see twelve dollhouses from the Victoria and Albert Museum in London, England, which contain amazing tiny furnishings. But those people who put together the exhibit also wanted visitors to know the characters inside.

    “It's 300 years of British homes told through their inhabitants (居民),” said Alice Sage, who is in charge of the London museum.

    So as visitors look inside the Tate Baby House, a fancy townhouse from 1760, they can push a button to hear a young woman get a lecture from her mother on the proper way to run a home. In the Killer Cabinet house, a servant named Betsy complains about the problems of city life in the 1830s. “We've got the cat to keep the rats away,” she says.

    That dollhouse was John Killer's gift to his wife and five daughters. The girls were allowed to play with the house, but they probably also learned a few lessons, Sage said.

    “The kitchen of the house would have been the perfect way to teach the girls about the management of a home,” she said, noting the tiny dishes and pots.

    Those who prefer a more modern look won't be disappointed. There are two rooms displaying a white dollhouse from 1935, an apartment house from the 1960s and a brightly colored 21st-century design.

    The end of the exhibit shows how imaginative design sometimes works best in small spaces.

    The Building Museum asked twenty-four artists, designers and architects from across the United States to each create a “dream room” from the past, present or future. Some of these unique small rooms were made using traditional furnishings, others from materials such as clay, insects, 3D-printing, and even peeps marshmallow candies!

Do you think you would work out more if you were offered money to do so? Science has shown that money can give people motivation to work out, but perhaps not in the way that you think.

According to a study published in the Annals of Internal Medicine Journal, the best strategy isn't offering money; it's giving someone money, then threatening to take it away.

Researchers gave 281 people the goal of walking 7,000 steps every day over 13 weeks.

To motivate the people who took part to reach the goal, researchers divided them into three groups.

People in the first group received $1.40(9 yuan) each day as long as they finished 7,000 steps, the second group was only able to collect the $1.40 if they had reached 7,000 steps the day before, and the third group was given $42 at the beginning of each month and $1.40 was taken away every time someone failed to meet the goal.

The third group met their daily fitness goals 50 percent more often than the other two groups, showing that people were most motivated to walk by the fear of losing money.

    “People are more motivated by losses than gains, and they like immediate gratification.” study author Dr Mitesh Patel, an assistant professor at the University of Pennsylvania in the US, told CNN. “They want to be rewarded today, not next year or far into the future.”

    Our brains tend to avoid wanting to lose things more than they try to get the benefits from gaining them, Patel explained. “It makes people think like the money is theirs to lose from day one.”

In addition, in most programs, many participants will drop out quickly and only the motivated will stay involved, Patel said.

    “In ours, we were pleasantly surprised that 96 percent stayed.” he added.

The study provides evidence that what matters is not only the money incentive （激励）, but also how you think about them. This is important to how effective they are. The evidence could have a big effect on health promotion programs in the future, according to the study.

“Incentives themselves are not all you need,” Stephanie Pronk, a health and wellness consultant with the Aonplc corporation, told The Wall Street Journal. “It's really important to change up the incentive design and keep people on their toes.”

    Can you imagine printing food? Some scientists are trying to revolutionize the dining experience by doing this. They hope that having a 3D printer in the kitchen will become as commonplace as the microwave. Scientists say that they are easy to use:you simply have to select a recipe and put the raw food "inks" into the printer. You can also change the instructions to make the food exactly how you want it. This means that it would be very quick and easy to create tasty and nutritious meals.

    They say that if people used 3D printers to create meals there would be less need for traditional growing, transporting and packaging processes as food production would be a lot easier. For example, alternative ingredients (原料) such as proteins from insects could be changed into tasty products. And as is known,those traditional activities are not beneficial to our surroundings.

    This technology could also help people who suffer from dysphagia (a swallowing disorder).The patients could program the printer and softer versions would be made so that they would not have trouble swallowing them.

    However,some people think that using 3D-printed foods would be a disaster. It could take away many jobs,including those for growing,transporting and packaging food. Imagine a world where there was no need for farming or growing crops and the same tastes could be printed from a raw "food ink". Likewise, traditional cafes and restaurants might lose business. Also, there are concerns about the nutritional value of printed food:is it really possible to get the nutrients we need from food-based inks?

    What's more, cooking and eating together with family and friends has long been a traditional and enjoyable activity. It is hard to imagine a world where the pastime of cooking is dead and meals can be created at the touch of a button.

    We know that St. Patrick's Day festivities may include a little bit of drinking. But there are plenty of kid-safe St. Patrick's Day events around metro Phoenix, too. Here are the lucky St. Patrick's Day celebrations for kids.

    3/17: Lucky St. Patrick's Day Cupcakes

    Kids can make their own treats at the Children's Museum of Phoenix this St. Patrick's Day. Children can make and decorate their cupcakes with rainbow candies and chocolate. To-go containers will also be provided.

    Details: 1-3 p.m. Friday, March 1. Children's Museum of Phoenix, 215 N.7^th Street, Phoenix. $ 3 for members. $ 4 for non-members. 602-253-0501.

    3/17-19: Fountain O' Green Artisan Market

    This community festival will include sculptures, paintings, handcrafted jewelry and clothes from selected local and regional artists, live music and dance performances throughout the weekend. There will also be a food court.

    On Friday, emerald-colored water will shoot from the town's fountain at noon. Take the kids to see the annual tradition and picnic in the park.

    Details: 10 a.m.-5 p.m, Friday-Sunday, March 17-19.Avenue of the Fountains and Saguaro Boulevard, Fountain Hills. Free. 480-488-2014.

    3-17: St. Patrick's Day Party at AZ Air Time

    Kids above 12 years old can collect their free, green glow necklaces and jump for three hours, scale the rock climbing wall or dive into the giant pit of foam（泡沫橡胶）. Jump socks required.

Details: 8-11p.m. Friday, March 17. AZ Air Time, 13802 N. Scottsdale Road, Suite 145, Scottsdale. $15, which is a $14 savings. 480-427-2000.