Your New Year's plan to move more is one of the toughest to stick to, and a group of scientists working with obese(过度肥胖的) mice think they're starting to understand why

    Rather than our sedentary(久坐的) lives causing weight gain, says Alexxai Kraviz, the National Institutes of Health neuroscientist who led the study, changes in brain chemistry after we start gaining weight affect our capacity to move.

    “Obses mice can move just fine,” says Kravitz, who published the work with his team in Cell Metabolism “They just don't.”

    What Kravitz's team found is that the activity of a particular dopamine(多巴胺) receptor linked to movement goes down as mice gain weight on a high-fat diet. So the nice slow down and they move less. And when the researchers restored the activity of that dopamine receptor—DR2—the mice started moving more, even though they were still obese. The team also saw that lean mice missing the DR2 receptor acted like obese mice. This is the target, says Kravitz—restoring that dopamine receptor function. “Maybe 20 or 30 years down the road, we could do that in people,” he says.

    And there is one more thing: The scientists fed normal mice and the mice lacking DR2 the same high-fat diet. Both sets of mice gained weight at the same rate.

    Kravitz says this is important because mice lacking DR2 move less from the get-go, whereas a normal mouse takes a little time to start seeing that dopamine receptor-related loss of exercise. The ability to exercise seems to be disconnected from weight gain, he says.

    “Exercise is a healthy thing to do, but its impact on weight loss has been exaggerated,” he says. “We have to be realistic about the size of the effect of exercise on weight, as opposed to health benefits.”

    Still, before you abandon your New Year's exercise plan, keep in mind that this study was done using a high-fat diet, and not the normal calorie restriction that people maintain when they diet.

    That's a big drawback to the work, says Vicki Vieira-Potter, a University of Missouri physiologist not involved in the study.

    “They feed the mice with high-fat diet, it damages the receptor, and that decreases activity. Those who plan to lost weight should remember high-fat diet is a nice way to cause obesity in the lab, but it's not the same as the normal situation of obesity,” she says.

    Sine also says that a lot of the weight gain in the mice came after they stopped moving around, which indicates that the loss of movement did impact obesity.

    It is said that if you want to stay young, sit down and have a good think. This is the research finding of a team of Japanese doctors, who say that most of our brains are not getting enough exercise — and as a result, we are growing old unnecessarily soon.

    Professor Taiju Matsuzawa wanted to find out why otherwise healthy farmers in northern Japan appeared to be losing their ability to think and reason at a relatively early age, and how the process of aging could be slowed down. With a team of colleagues at Tokyo National University, he set about measuring brain volumes of a thousand people of different ages and varying occupations. Computer technology enabled the researchers to obtain precise measurements of the volume of the front and side parts of the brain, which controls functions like eating and breathing, does not contract with age, and one can continue living without intellectual on economical faculties. Contraction of front and side parts — as cells die off — was observed in some subjects in their thirties, but it was still not evident in some sixty-and seventy-year-olds. Matsuzawa concluded from his tests that there is a simple way to the contraction normally connected with age — using the head.

    The findings show in general terms that contraction of the brain begins sooner in people in the country than in the town. Those least at risk, says Matsuzawa, are lawyers, followed by university professors and doctors. White collar workers doing routine work in government offices are, however, as likely to have shrinking (萎缩) brains as the farm worker, bus driver and shop assistant.

    Matsuzawa's findings show that thinking can prevent the brain from shrinking. Blood must circulate properly in the head to supply the fresh oxygen the brain cells need. “The best way to maintain, good blood circulation is through using the brain.” he says. “Think hard and engage in conversation. Don't rely on pocket calculators.”

根据短文内容，选择最佳答案，并将选定答案的字母标号填在题前括号内。

    There are many theme parks in Florida. These amusement parks are designed for kids big and small and have plenty to offer adults, too.

    Magic Kingdom

    Orlando is the center of theme parks in Florida. Of all the parks, no trip to Orlando would be complete without a visit to Magic Kingdom. The center of Disney world, with Main Street USA and Cinderella's Castle, is here at Magic Kingdom. There are rides for kids of all ages as well as shopping and dining.

    Epcot

    After Magic Kingdom, the best-known theme park in Disney World is Epcot. This is a good place for curious kids who want to learn about the planets, the stars, and the workings of the human body. The good and wine festival is another big draw to Epcot.

    Animal kingdom

    When it comes to the top 4 Florida theme parks, Animal kingdom must be on the list. You may have had the chance to go to a zoo before, but Animal kingdom brings the concept of a zoo to new heights. Sure you can go on the safari (狩猎旅行), but there are also rides on different animals, even dinosaurs.

    Universal's Island of Adventure

If your kids have the need for speed, you will surely want to check out Universal's Island of Adventure. Here roller coasters and thrill rides will combine the magic of the movies with plenty of twists (旋转) and turns. You'll also find Wizarding World of Harry Potter here—something the whole family is sure to enjoy.

    Thirteen-year-old Kaylee has a lot of friends—532, actually, if you count up both her Instagram followers and Facebook friends. And she spends a lot of time with them.

    But is it possible that Kaylee's online friendships could be making her lonely? That's what some experts believe Connecting online is a great way to stay in touch, they say. However, some experts worry that many kids are so busy connecting online that they might be missing out on true friendships.

    Could this be true? During your parents' childhoods, connecting with friends usually means spending time with them in the flesh. Kids played Scrabble around a table, not Words With Friends on their phones. When friends missed each other, they picked up the telephone. Friends might even write letters to each other.

    Today, most communication takes place online. A typical teen sends 2,000 texts a month and spends more than 44 hours per week in front of a screen. Much of his time is spent on social media platforms like Instagram and Facebook.

    In fact, in many ways, online communication can make friend ships stronger, “There's definitely positive influence. Kids can stay in constant contact, which means they can share more of their feelings with each other,” says Katie, co-author of the App Generation.

    Other experts, however, warn that too much online communication can get in the way of forming deep friendships. “If we are constantly checking in with our virtual worlds, we will have little time for our real world friendships.” says Rosen, a professor at California State University.

    Rosen also worries that today s kids might mistake the “friends” on the social media for true friends in life. However, in tough times, you didn't need someone to like your picture or share your tweet. You needed someone who would keep your secrets and hold your hand. You would like to talk face to face.

    When my father married my mother in 1943 he gave my mother a 1937 crown coin and told her to keep it in the back of her purse and not spend it. This would mean that she always felt that she was protected and would always have money if she really needed it.

    When I was married in 1970 my husband who had heard this story obtained a 1937 crown for me and I have always kept it in my wallet and I have always had enough for my needs.

    A friend recently fell on hard times partly through external (外部的) circumstances and partly through poor planning. Friends and I have loaned her money, paid her bills, even given her food and tried to teach her budget techniques, but none of them has been a solution. She has just slipped deeper and deeper into financial trouble and depression.

    Last week she looked pale and unwell, very depressed and hopeless. I then thought about how the crown, a reminder of another's care and love, had protected me so I went to the bank for a $100 dollar bill. I told my friend the story and asked her to keep the $100 in the back of her wallet. It turned out that she didn't have a wallet so she put the money in a little pencil case where she kept her coins. She immediately felt better. "I feel rich and thank you for being a good friend" she said and we were both a bit teary.

    The reason for passing this on is not to praise any generosity on my part but to show the power of "random acts of kindness". I went home and remembered a little wallet I had that I'd never used and thought "I'll give that to my friend." I opened it and inside found $100. The universe is very just and if your heart is open the reward always comes.

    Failure is probably the most exhausting experience a person ever has. There is nothing more tiring than not succeeding.

    We experience this tiredness in two ways: as start-up fatigue(疲惫) and performance fatigue. In the former case, we keep putting off a task because it has either too boring or too difficult. And the longer we delay it, the more tired we feel.

    Such start-up fatigue is very real, even if not actually physical, not something in our muscles and bones. The solution is obvious though perhaps not easy to apply: always handle the most difficult job first.

    Years ago, I was asked to write 102 essays on the great ideas of some famous authors. Applying my own rule, I determined to write them in alphabetical(按字母顺序), never letting myself leave out a tough idea. And I always started the day's work with the difficult task of essay-writing. Experience proved that the rule works.

    Performance fatigue is more difficult to handle. Though willing to get started, we cannot seem to do the job right. Its difficulties appear so great that, however hard we work, we fail again and again. In such a situation, I work as hard as I can-then let the unconscious take over.

    When planning Encyclopaedia Britannica (《大英百科全书》), I had to create a table of contents based on the topics of its articles. Nothing like this had ever been done before, and day after dat I kept coming up with solutions, but none of them worked. My fatigue became almost unbearable.

    One day, mentally exhausted, I wrote down all the reasons why this problem could not be solved. I tried to convince myself that the trouble was with the problem itself, not with me. Relived, I sat back in an easy chair and fell asleep.

    An hour later, I woke up suddenly with the solution clearly in mind. In the weeks that followed, the solution which had come up in my unconscious mind provided correct at every step. Though I worked as hard as before, I felt no fatigue. Success was now as exciting as failure had been depressing.

    Human beings, I believe must try to succeed. Success, then, means never feeling tired.