Exercise may help to safeguard the mind against depression(沮丧) through previously unknown effects on working muscles, according to a new study involving mice.

    Mental health experts have long been aware that even mild, repeated stress can contribute to the development of depression and other mood disorders in animals and people. Scientists have also known that exercise seems to cushion against depression. But precisely how exercise, a physical activity can reduce someone's risk for depression, a mood state, has been mysterious. So for the new study, researchers at the Karolinska Institute in Stockholm studied the brains and behavior of mice in a complicated and novel fashion.

    We can't ask mice if they are feeling cheerful or in low spirits. Instead, researchers have pictured certain behaviors that indicate depression in mice. If animals lose weight, stop seeking out a sugar solution when it's available — because, probably, they no longer experience normal pleasures — or give up trying to escape from the cold-water zone just freeze in place, they are categorized as depressed. And in the new experiment, after five weeks of frequent but low-level stress, such as being lightly shocked, mice displayed exactly those behaviors. They became depressed.

    The scientists could then have tested whether exercise blunts (延缓) the risk of developing depression after stress by having mice run first. But, frankly, from earlier research, they wanted to know how, so they bred pre-exercised mice. A wealth of earlier research by these scientists and others had shown that aerobic exercise, in both mice and people, increases the production within muscles of an enzyme (酶) called PGC-1alpha. The Karolinska scientists suspected（怀疑） that this enzyme somehow creates conditions within the body that protect the brain against depression. Then, the scientists exposed the animals, which without exercising, were in high levels of PGC-1alpha to five weeks of mild stress. The mice responded with slight symptoms of worry. But they did not develop depression. They continued to seek out sugar and fought to get out of the cold-water zone. Their high levels of PGC-1alpha appeared to make them depression-resistant（抵抗的）. Finally, to ensure that these findings are relevant to people, the researchers had a group of adult volunteers complete three weeks of frequent endurance training, consisting of 40 to 50 minutes of moderate cycling or jogging. The scientists conducted muscle biopsies (活体检查) before and after the program and found that by the end of the three weeks, the volunteers' muscle cells contained substantially more PGC-1alpha than at the study's start.

    The finding of these results, in the simplest terms, is that “you reduce the risk of getting depression when you exercise,” said Maria Lindskog, a researcher at the Karolinska Institute.

    Why is pink or purple a color for girls and blue or brown for boys?

The answer depends largely on cultural values as well as personal experiences. To the Egyptians, green was a color that represented the hope and joy of spring, while for Muslims, it means heaven. Red is a symbol of good luck in many cultures. In China, children are given money in a red envelope to bring good fortune in the New Year. For many nations, blue is a symbol of protection and religious beliefs. Greek people often wear a blue necklace hoping to protect themselves against evils (灾祸).

    People's choice of colors is also influenced by their bodies' reactions (反应) toward them. Green is said to be the most restful color. It has the ability to reduce pain and relax people both mentally and physically. People who work in green environment have been found to have fewer stomachaches.

Red can cause a person's blood pressure to rise and increase people's appetites (食欲). Many decorators will include different shades of red in the restaurant. Similarly, many commercial (商业的)websites will have a red “Buy Now” button because red is a color that easily catches a person's eye.

    Blue is another calming color. Unlike red, blue can cause people to lose appetite. So if you want to eat less, some suggest that eating from blue plates can help.

    The next time you are deciding on what to wear or what color to decorate your room, think about the color carefully.

    See a cell phone cover that you like on Taobao? Forget about placing an order, paying the bill online and waiting for days for it to be delivered to you. In the near future, you'll be able to get it in minutes just by hitting "print" on your computer. You might find it hard to believe that you could actually "print" an object as you would a picture. But it is not that hard to understand how it would work. Just as a traditional printer sprays (喷) ink onto paper line by line, modem 3-D printers spread material onto a surface layer by layer, from the bottom to the top, gradually building up a shape.

    Instead of ink, the materials the 3-D printer uses are mainly plastic, resin (树脂) and certain metals. The thinner each layer is — from a millimeter to less than the width of a hair —the smoother and finer the object will be. This may sound like a completely new technology, but the truth is that 3-D printing has been around since the late 1980s. Back then, it was barely affordable for most people, so few knew about it.

Last year, though, saw a big change in the 3-D printing industry — printers became much cheaper. For example, 10 years ago a desktop 3-D printer might have cost £20,000, while now they cost only about £ 1,000, according to the BBC. Taken out of the factory and introduced to more diverse and common uses, 3-D printing can create just about anything you can think of — flutes (笛子), bikinis, jewelry, aircraft parts and even human organs. In fact, scientists from Cornell University in New York have just made an artificial ear using a 3-D printer, according to Science Daily. The fake ear looks and acts exactly like a natural one.

    However, as 3-D printing becomes more common, it may bring about certain problems —such as piracy. "Once you can download a coffee maker, or print out a new set of kitchen utensils (餐具) on your personal 3-D printer, who will visit a retail (零售的) store again?", an expert in 3-D printing told Forbes News. Even more frightening, what if anyone in the world could use a 3-D printer to print out a fully functioning gun?

    The Panda Ant is a most unusual species with a lovely appearance. {#blank#}1{#/blank#} They look like ants but actually they belong to the wasp（黄蜂）family. The differences between the two sexes of the species are also very pronounced in both appearance and behavior. When fully grown, the male, possibly attaining a length of approximately 0. 8 centimeters, is several times larger than the female. {#blank#}2{#/blank#} Cute as panda ants may look, they are dangerous and capable of knocking out an animal much larger than they are with a few stings（刺）.

    Panda ants primarily depend on flowers sweet liquid as their food. {#blank#}3{#/blank#} The female panda ant often lays its eggs in a bee or wasp nest. When the young ones. hatch, they will eat their pupa（蛹）hosts.

    {#blank#}4{#/blank#} So although a female panda ant lays approximately 2, 000 eggs a year, a considerable amount of eggs to support their survival, this species is still on the edge of dying out.

    This species was first discovered in the coastal region of Central Chile in 1938. {#blank#}5{#/blank#}

    Today, they are likely to be found in dry desert and sandy areas such as Southwestern United States and parts of Mexico.

A. It's a new fashion to raise panda ants as pets.

B. The name comes from their colors as pandas.

C. Yet young panda ants are meat-eaters.

D. No one believes the panda ant is the relative of bees.

E. Besides, the males are active at night while the females opposite.

F. Unfortunately, many panda ants are eaten for their bright colors.

G. Then little attention was given to it until recently.

    For the rest of March, a disease will sweep across the US. It will keep kids home from school. {#blank#}1{#/blank#} Employees will suddenly lose their ability to concentrate.

    The disease, known as "March Madness", refers to the yearly 65-team US men's college basketball tournament (锦标赛). {#blank#}2{#/blank#} Teams compete against each other in a single-elimination (单局淘汰) tournament that eventually crowns a national champion.

    Nearly 20 million Americans will find themselves prisoners of basketball festival madness. The fun comes partly from guessing the winners for every game. Friends compete against friends. {#blank#}3{#/blank#} Colleagues against bosses.

    Big-name schools are usually favored to advance into the tournament. But each year there are dark horses from little-known universities.

    This adds to the madness. Watching a team from a school with 3, 000 students beat a team from a school with 30, 000, for many Americans, is an exciting experience. Two years ago, the little-known George Mason University was one of the final four teams. {#blank#}4{#/blank#}

    College basketball players are not paid, so the game is more about making a name for their university and themselves. {#blank#}5{#/blank#} About 4 billion will be spent gambling (赌) on the event. According to Media Life magazine, the event will bring in 500 million in advertising income this year, topping the postseason income of every US professional league, including that of the NBA.

    A new officer with the Huntington Park Police patrols (巡逻) local parks 24 hours a day seven days a week. He doesn't need rest, coffee breaks, a salary or medical insurance, and that is because it is a Robocop.

    The main function of the Robocop is to scan and film the surroundings. Besides cameras with night vision that report 360 degrees, it also has a distress button which is located here, so if somebody is to need assistance or they want to contact the communication center, they can do it by way of that distress button. There are people that are monitoring on the other end.

    This newest police employee is self-charging. It's easy to program it and make changes to the software if necessary. Its maintenance (维护) costs are roughly 75 thousand dollars a year. It travels the entire park. It is a programmed path, but the police are able to change the path and adapt it.

    The Robocop can record the license plates (车牌) of passing cars and check them against an online database of stolen cars. It can also help locate a lost iPhone because it is able to determine a smartphone's MAC address. The police can see from the robot if something wrong happens and then come and figure it out.

    The Robocop can't replace its human handlers. The whole goal is to give police more time to do things machines can't do. The police have been having some concerns about safety of the parks and want an extra set of eyes that will help patrol a 24/7.Robocop's creators believe this model known as K5 is best used for providing security at public places like hospitals, parking lots, parks and airports. So far, it seems to be working out just fine.