A report says older adults who test their minds with increasingly difficult projects have better mental ability than those who do less demanding activities.

    To keep our brains sharp as we age, we are often told to keep our minds active. As the old saying goes, “Use it or lose it.” But, there is very little scientific evidence to support than.

Denise Park is head of the university's Center for ? Vital Longevity. She designed a study in which she and her tern placed 221 healthy aging and older adults into one of three groups.

    “We asked people to learn new things, like quilting or photography. We asked other people to just do fun things like being in a social group function but were not likely to have a very large effect.”

    The subjects took part in their assigned activities for 15 hours a week over three months. At the end of that time, the researchers found that the adults who learned new skills, such as digital photography, showed the greatest improvements on memory tests.

    No improvements were seen in the results of those in the social group that did activities together like going on field trips. There were also no improvements among the third group that listened to classical music or did crossword puzzles.

    Denise Park believes one reason for improved memory in the active learning group is that its members were being pushed to learn new skills. The other groups took part in what she call receptive activities. Learning new skills may not cure age-related mental decline. But, Ms. Park thinks being mentally active slows down the process.

Denise Park says the latest information shows that the improvements lasted for at least a year. She and her team plan to do longer follow-up studies with all three groups. She also is interested in learning whether taking part in demanding mental activities delays the development of conditions like Alzheimer's disease.

    Easter(复活节) is still a great day for worship, randy in baskets and running around the yard finding eggs, but every year it gets quite a bit worse for bunnies.

    And no, not because the kids like to pull their ears. The culprit is climate change, and some researchers found that rising temperatures arc having harmful effects on at least five species of rabbit in the US.

    Take the Lower Keys March rabbit, for instance. An endangered species that lives in the Lower Florida Keys, this species of cottontail is a great swimmer — it lives on the islands! — but it is already severely affected by development and now by rising levels. According to the Center for Biological Diversity, an ocean level rise of only 0. 6 meters will send these guys jumping to higher ground and a 0.9-meter rise would wipe out their habitat (栖息地) completely.

    The snowshoe hare, on the other hand, has a color issue. Most of these rabbits change their fur color from white in the wintertime to brown in the summer, each designed to give them better cover from predators（捕食者）. As the number of days with snow decreases all across the country, however, more and more bunnies arc being left in white fur during brown dirt days of both fall and spring, making them an easier mark for predators. Researchers know that the color change is controlled by the number of hours of sunlight, but whether the rabbit will be able to adapt quick enough to survive is a big question. The National Wildlife Federation has reported that hunters have noticed their numbers are already markedly down.

    American pikas or rock rabbits, a relative of rabbits and hares, might be the firs' of these species to go extinct due to climate change. About 7-8 inches long, pikas live high in the cool, damp mountains west of the Rocky Mountains. As global temperatures rise, they would naturally migrate (迁徙) to higher ground — but they already occupy the mountaintops. They can't go any higher. The National Wildlife Federation reports that they might not be able to stand the new temperatures as their habitat beats up.

    The volcano rabbit has the same problem. These rabbits live on the slopes of volcanoes in Mexico, and recent studies have shown that the lower range of their habitat has already shifted upward about 700 meters, but there are not suitable plants for them to move higher, so they are stuck in the middle. Scientists are concerned about their populations.

    Native to the US, pygmy rabbits weigh less than 1 pound and live in the American West. They are believed to be the smallest rabbits in the world. Their habitats have been destroyed by development. Several populations, such as the Columbia Basin pygmy, almost went extinct and were saved by zoo breeding programs. Pygmy rabbits also rely on winter cover by digging tunnels through the snow to escape predators, but lesser snowfall is leaving them exposed.

All of this gives new meaning to dressing up in a giant bunny costume this Easter.

    You're out to dinner. The food is delicious and the service is fine. You decide to leave a big fat tip. Why? The answer may not be as simple as you think.

    Tipping, psychologists have found, is not just about service. Instead, studies have shown that tipping can be affected by psychological reactions to a series of different factors from the waiter's choice of words, to how they carry themselves while taking orders, to the bill's total. Even how much waiters remind customers of themselves can determine how much change they pocket by the end of the night.

    “Studies before have shown that mimicry(模仿) brings into positive feelings for the mimicker,” wrote Rick van Baaren, a social psychology professor. “These studies show that people who are being mimicked become more generous toward the person who mimics them.”

    So Rick van Baaren divided 59 waiters into two groups. He requested that half serve with a phrase such as. “ Coming up !” Those in the other hall were instructed to repeat the orders and preferences back to the customers. Rick van Baaren then compared their take-home pay. 'The results were clear—it pays to mimic your customer. The copycat(模仿者) waiters earned almost double the amount of tips to the other group.

    Leonard Green and Joel Myerson, psychologists at Washington University in St. Louis, found the generosity of a tipper maybe limited by his bill. After research on the 1,000 tips left for waiters, cabdrivers, hair stylists, they found tip percentages in these three areas dropped as customers' bills went up. In fact, tip percentages appear to plateau(稳定期) when bills topped $100 and a bill for $200 made the worker gain no bigger percentage tip than a bill for $100.

    “That's also a point of tipping,” Green says. “You have to give a little extra to the cabdriver for being there to pick you up and something to the waiter for being there to serve you. If they weren't there, you'd never get any service. So part of the idea of a tip is for just being there.”

    Laptop computers are popular all over the world. People use them on trains and airplanes, in airports and hotels. These laptops connect people to their workplace. In the United States today, laptops also connect students to their classrooms.

    Westlake College in Virginia will start a laptop computer program that allows students to do schoolwork anywhere they want. Within five years, each of the 1500 students at the college will receive a laptop. The laptops are part of a $10 million computer program at Westlake, a 110-year-old college. The students with laptops will also have access to the Internet. In addition, they will be able to use e-mail to "speak" with their teachers, their classmates, and their families. However, the most important part of the laptop program is that students will be able to use computers without going to computer labs. They can work with it at home, in a fast-food restaurant or under the trees—anywhere at all!

    Because of the many changes in computer technology, laptop use in higher education, such as colleges and universities, is workable. As laptops become more powerful, they become more similar to desktop computers.

    In addition, the portable computers can connect students to not only the Internet, but also libraries and other resources. State higher-education officials are studying how laptops can help students. State officials are also testing laptop programs at other universities, too.

    At Westlake College, more than 60 percent of the staff use computers. The laptops will allow all teachers to use computers in their lessons. As one Westlake teacher said, "Here we are in the middle of Virginia and we're giving students a window on the world. They can see everything and do everything."

    I am afraid of heights but two summers ago I climbed to a high place. Most of our high school had come along on a day trip to a beautiful beach village in Peru. After eating our lunches, many of us wanted to make the climb to an area around the village.

    Do I turn back? "Yes!" Will I regret (后悔))it later? I really want to get to the top, but... At last, I decided at least to have a try.

    My friend Tom was in front of me. Then, suddenly, he slipped (滑倒))and was about 10 feet back! My heart was beating faster until he stopped himself. Knowing that my friend Seth would be right behind me, I began the climb. I was soon past the first challenge safely, but not feeling much better about the rest of the climb. Looking down, I saw rocks everywhere. My breathing sped up, and my heart beat even faster, growing loud in my ears.

    My friends kept climbing. But they did not forget me. Someone was always behind me to help hold my feet when necessary, and someone else was always in front to offer a hand up. With friends helping me by words and actions, I slowly gained ground.

    Then we came to the worst part. The climb looked very close to vertical (垂直的). To me, the wise choice was to go back down. Melody encouraged me to go on and she made it safely first. I stopped, unsure of my footing. "You can do it, Jean! I'm right here," Melody called. She waited patiently, not asking me to hurry. I took a few deep breaths and kept climbing.

    With no more mistakes, we came to the top finally. I was dirty and tired. But it didn't matter. I was at the top! I had never felt so alive.

    When a terrible earthquake hit, many people were killed and many houses fell down. After the earthquake, all the newspapers reported many stories about some of the families who were in trouble.

    One Sunday, when I was reading a newspaper, a special picture touched me. It gave the clothing sizes of each family member. I thought that this would be a good chance to teach my children to help those who were less lucky than ourselves. I said to my seven-year-old twins, Brad and Brett, and three-year-old Meghan. "We have so much, and these poor people now have nothing. We'll share what we have with them."

    I filled a box with foods and clothes. While I was doing this, I encouraged the boys to choose their toys and donate some of their less favorite things. Meghan watched quietly as the boys took out their old toys and games and put them together. Then she walked away. A few minutes later she came back with Lucy, her much-loved doll. She put the doll on top of the other toys. "Oh, dear," I said. "You don't have to give Lucy. You love her so much." Meghan said, "Lucy makes me happy, Mommy. Maybe she'll make another little girl happy, too."

    I looked at Meghan for a long moment. She taught me a lesson. It's easy to give something that we don't want any more, but harder to give what we cherish (珍爱), isn't it?