The next time you go grocery shopping, try speaking to other customers. One summer day, I took a smile and a warm heart into a small store in Oregon and got far more than groceries.

    I love fresh produce(农产品) in the store, and not just for the amazing colors provided by summer's bounty (慷慨) or the chance to joy over new choices from other countries. It's also because I just love watching people pick their produce.

    The day I was there I found a sale on amazing cherry tomatoes—along with a woman in her late 70s. Despite the fact that we were strangers, we began to discuss apples. She noted a problem with the Pink Ladies. "They tasted like I was eating an unripe green apple from the tree," she said, twisting her face as if still tasting the sour apple.

    I wondered if this is something most of my generation can even remember doing. I surely do. I mentioned that I often could not resist the green yet tempting fruit swinging from an apple tree. This was the start for a series of discussions as we shopped-covering such topics as nutrition, new foods and the quality of produce.

    By this time a third woman had joined in our conversation. The three of us continued along, unexpected friends, chatting about family size and the troubles a mom might have serving healthful foods that please the whole family.

    Eventually we all went our separate ways, but in the dairy(奶制品) section I heard a small voice say, "I finally caught up with you." It was the first woman I'd talked to, extending a bag of apricots(杏) to me. "I don't know if your family will eat these," she added, "but they have a super deal on them."

    Again I was brought back to my childhood, when I also ate apricots straight from the tree. My mouth watered at the remembered flavor.

    The old lady didn't realize that she'd given me far more than produce. With that offering came a sense of community, a flashback to days when it was OK to talk to a stranger. She brought back memories of summer fruits right from the tree—and a feeling that somehow those apricots were a thank-you for sharing my time with her in a very unlikely place.

    The advice offered from any other 82-year-olds might have made young people yawn and roll their eyes. But when former South African president Nelson Mandela advised two dozen local youth leaders in Los Angeles to take education seriously, his audience was listening.

    The famed old man said to the young people that if they expected to improve the lives of others in the future, they must work at improving their own lives now. "Education is one of the most important weapons you have,” Mandela advised. “It will place you in a far better position to serve yourself and your community.”

“The point is, he was young once and rebellious(叛逆的)once and he kept his dream alive, just as you each have dreams,” explained South Africa's ambassador to the United States, Sheila Sisulu, as she introduced Mandela to the young crowd.

    Asked for specific advice about changing society by 21-year-old Ahmed Younis, Mandela suggested that somehow helping arouse more American interest in foreign affairs might be a start.

There is an impression that Americans, in general, have not followed international developments properly, Mandela said. “I'm not making that statement myself, but there are serious political analysts who say Americans are not well informed as to what has happened in the world.”

22-year-old Omari Trice said Mandela left him full of enthusiasm. “ He's a person who set the tone for an entire nation, said Trice. “You come away feeling you need to be a superman in order to get things done.”

    A team of engineers at Harvard University has been inspired by Nature to create the first robotic fly. The mechanical fly has become a platform for a series of new high-tech systems. Designed to do what a fly does naturally, the tiny machine is the size of a fat housefly. Its mini wings allow it to stay in the air and perform controlled flight tasks.

    “It's extremely important for us to think about this as a whole system and not just the sum of a bunch of individual components,” said Robert Wood, the Harvard engineering professor who has been working on the robotic fly project for over a decade. A few years ago, his team got the go-ahead to start piecing the components together. “The added difficulty with a project like this is that actually none of those components are off the shelf and so we have to develop them all on our own,” he said.

    They engineered a series of systems to start and drive the robotic fly. “The seemingly simple system which just moves the wings has a number of interdependencies on the individual components, each of which individually has to perform well, and then has to be matched well to everything it's connected to,” said Wood. The flight device was built into a set of power, computation, sensing and control systems. Wood says the success of the project proves that the flying robot with these tiny components can be built and manufactured.

    Wood says the design offers a new way to study flight mechanics and control at insect-scale. Yet, the power, sensing and computation technologies on board could have much broader applications. “You can start thinking about using them to answer open scientific questions, you know, to study biology in ways that would be difficult with the animals, but using these robots instead,” he said. “So there are a lot of technologies and open interesting scientific questions that are really what drives us on a day to day basis.”

    Wolves travel shorter distances and move slower during snowfall events, according to new research by University of Alberta biologists. The effects were most pronounced at night, when wolves hunt, and behaviour returned to normal within a day. Wolf tracks across snow in northeastern Alberta.

    "Our findings suggest that there is something about actively falling snow that causes wolves to slow down," said Amanda Droghini, a former MSc student in the Department of Biological Science and lead author on the study. "We don't know the exact mechanism behind that. It's unlikely that they were staying still because they were feasting on a recent kill. Instead, active precipitation(降雪量)might affect wolves' hunting abilities. Like rain, snow clears the air column of scent molecules. So, maybe falling snow makes it harder for wolves to detect the smell of prey."

    Over the course of two winters, the researchers used remote cameras to disclose snowfall events and estimate snow depth. To study wolf movement, they collected telemetry(测距仪) data from 17 wolves to calculate travel speed and duration, as well as resting periods. It is the first study to examine how large flesh-eating animals respond to snowfall events.

    With the effects of climate change on precipitation in the north forest region uncertain, it is difficult to predict the implications for wolf populations. Studies such as these increase our understanding of how large mammals react to normal snowfall events, but the type and amount of winter precipitation will likely have an impact on animal behavior and the energetic cost of movement.

    "Winter is already challenging for many wildlife species because moving through snow requires more energy. Snow can also make it harder for animals to access food resources," said Droghini, who conducted the research under the supervision of Professor Stan Boutin, Alberta Biodiversity Conservation Chair.

    "Anything that increases those costs, such as increased rain-on-snow events, could lead to lacking in nutrition, poor body condition, and even starvation as animals are unable to make up for those additional costs. That is one of the worst-case scenarios(设想)but, in truth, we know very little about potential changes to precipitation patterns and how wildlife will respond to those changes."

    Shop with Your Doc is part of a broader and still growing movement in US medicine to shift the focus away from simply treating disease toward caring for the whole person. It is meant to help people make educated, healthy choices one grocery cart at a time. Across the country, hospitals are setting up food banks and medical schools are putting cooking classes on the curriculum. Nonprofits are connecting medical centers with community resources to ensure that low-income Americans have access to fresh fruits and vegetables.

    For centuries, Western medicine's mission was to cure disease. But over the past generation, two generation, two significant trends are of concern to the medical community, says Timothy Harlan, executive director of Goldring Center for Culinary Medicine at Tulane University in New Orleans. Healthcare costs began to soar (激增), and relatively inexpensive, poor-quality food became more common. "There's a very straightforward link between people improving their diets and improving the condition that they have," Dr. Harlan says.

    The connection drove the medical and nonprofit communities to rethink their approach to health. What emerged was the concept of the "social determinants of health"—the notion of taking into account the biological, physical, and socioeconomic circumstances surrounding a patient. A healthy person isn't just someone who is free from disease, the theory goes; he or she also enjoys "a state of complete mental, physical and social well-being."

    The question the medical community now faces is how to get patients—especially low-income families—to recognize these determinants and make it possible for them to eat and live healthier. In Boston, medical experts responded by creating an on-site pantry (食品室) at Boston Medical Center. Since its founding in 2002, the pantry has evolved into a kind of nutrition center where primary care providers at BMC send patients for food. Today the pantry, which gets 95 percent of its stock from the Greater Boston Food bank, hosts free cooking classes and serves about 7,000 people a month. The Greater Boston Food Bank has also launched its own initiatives, striking partnerships with four community health centers across the state to offer free mobile produce markets. The organization also helped develop toolkits (软件包) that map local pantries, markets that accept government food vouchers, and other resources.

    At Tulane in New Orleans, Harlan is leading the development of a curriculum that combines medicine with the art of food preparation. His philosophy: Doctors who know their way around a kitchen are better at helping their patients. And empowering patients to take charge of their own diets is one way to help them deal with the incredible costs of health care, Harlan says. The curriculum has since been adopted at 35 medical schools around the United States. Chipping away at bad habits is a good place to start getting patients to think about the choices they make for themselves and their families, say Dr Maureen Villasenor, the Orange County pediatrician (儿科医生).

    Science has a lot of uses. It can uncover laws of nature, cure diseases, make bombs, and help bridges to stand up. Indeed science is so good at what it does that there's always a temptation(诱惑) to drag it into problems where it may not be helpful. David Brooks, author of The Social Animal: The Hidden Sources of Love, Character, and Achievement, appears to be the latest in a long line of writers who have failed to resist the temptation.

    Brooks gained fame for several books. His latest book The Social Animal, however, is more ambitious and serious than his earlier books. It is an attempt to deal with a set of weighty topics. The book focuses on big questions: What has science revealed about human nature? What are the sources of character? And why are some people happy and successful while others aren't?

    To answer these questions, Brooks surveys a wide range of disciplines(学科). Considering this, you might expect the book to be a dry recitation of facts. But Brooks has structured his book in an unorthodox(非常规的), and perhaps unfortunate, way. Instead of introducing scientific theories, he tells a story, within which he tries to make his points, perhaps in order to keep the reader's attention. So as Harold and Erica, the hero and heroine in his story, live through childhood, we hear about the science of child development and as they begin to date we hear about the theory of sexual attraction. Brooks carries this through to the death of one of his characters.

    On the whole, Brooks' story is acceptable if uninspired. As one would expect, his writing is mostly clear and, to be fair, some chapters stand out above the rest. I enjoyed, for instance, the chapter in which Harold discovers how to think on his own. While Harold and Erica are certainly not strong or memorable characters, the more serious problems with The Social Animal lie elsewhere. These problems partly involve Brooks' attempt to translate his tale into science.