Recent summer temperatures in parts of Australia were high enough to melt asphalt. As global warming speeds up the heat and climatic events increase, many plants may be unable to cope. But at least one species of eucalyptus tree can resist extreme heat by continuing to “sweat” when other essential processes stop, a new study finds.

    As plants change sunlight into food, or photosynthesize (光合作用), they absorb carbon dioxide through pores on their leaves. These pores also release water via transpiration(蒸腾), which circulates nutrients through the plant and helps cool it by evaporation(蒸发). But exceptionally high temperatures are known to greatly reduce photosynthesis—and most existing plant models suggest this should also decrease transpiration, leaving trees in danger of fatally overheating. Because it is difficult for scientists to control and vary trees' conditions in their natural environment, little is known about how individual species handle this situation.

    Ecologist John Drake of the S.U.N.Y. College of Environmental Science and Forestry and his colleagues grew a dozen Parramatta red gum (Eucalyptus parramattensis) trees in large, climate-controlled plastic pods that separated the trees from the surrounding forest for a year in Richmond, Australia. Six of the trees were grown at surrounding air temperatures and six at temperatures three degrees Celsius higher. The researchers withheld (扣留) water from the surface soil of all 12 trees for a month to imitate a mild dry spell, then induced a four-day “extreme” heat wave: They raised the maximum temperatures in half of the pods（three with surrounding temperatures and three of the warmer ones）— to 44 degrees ℃.

    Photosynthesis ground to a near halt in the trees facing the artificial heat wave. But to the researchers' surprise, these trees continued to transpire at close-to-normal levels, effectively cooling themselves and their surroundings. The trees grown in warmer conditions coped just as well as the others, and photosynthesis rates bounced back to normal after the heat wave passed, Drake and his colleagues reported online in Global Change Biology.

    The researchers think the Parramatta red gums were able to effectively sweat — even without photosynthesis — because they are particularly good at tapping into water deep in the soil. But if a heat wave and a severe drought (干旱) were to hit at the same time and the groundwater was exhausted, the trees may not be so lucky, Drake says.

    Other scientists call the finding encouraging. “It's definitely good news,” says Trevor Keenan, an ecologist at Lawrence Berkeley National Laboratory, who was not part of the study. “It would be very interesting to know how this translates to other species,” he adds. Drake hopes to conduct similar experiments with trees common in North America.

                                                                                         The University of Sheffield

    Back to its origin

    The University of Sheffield is a research university in the city of Sheffield in South Yorkshire, England. It is one of the original “red brick” universities, which are a group of top and famous old universities. The University of Sheffield was originally formed by the combination of three colleges. The Sheffield School of Medicine was founded in 1828, followed in 1879 by the opening of Firth College by Mark Firth, a steel manufacturer (制造商), to teach arts and science subjects. Firth College then helped to provide money for the opening of the Sheffield Technical School in 1884 to teach applied science. In 1897 the three institutions were joined together to form the University College of Sheffield, which in turn became the University of Sheffield by Royal Charter (特许) in 1905. This university is famous for its good education and boasts a number of Nobel Prize winners among its former students.

    More information

    System: The University has five departments: Arts and Humanities; Engineering; Pure Science; Social Sciences; Medicine, Dentistry and Health. Sheffield also has many research programs in fields including aerospace, environmental science, psychology, and biology.

    City show: Sheffield is a lively city in the north of England. Sheffield is known as the greenest city in Europe because of its 2 million trees. As a result, there are many parks and woods throughout the city and beyond. Sheffield is the greenest city in England with 150 woodlands and 50 public parks within the city. Once, in Sheffield, the folk hero—Robin Hood lived in Sherwood Forest with 150 of his loyal friends. And Charlotte Bronte, the English writer noted for her novel Jane Eyre was born in Sheffield.

    I stepped on the red carpet and smiled as the cameras rushed up to take pictures. I slowly walked into the large hall of my first Hollywood premiere(首映). I had designed the special effects for the hottest movie on the market. Later, a friend of mine came with a big smile on her face. “I'm sure you have never thought that you would be here,” she said excitedly. I calmly smiled back in return.

    Having never had great opportunities, I've worked long and hard to create a bright future. Though I grew up in a poor family, I never doubted that my future goals would be connected with computers. In middle school I became the producer of a daily news television show.

    My future goal became even more possible when a new high school in my area held a technology program created for students interested in technology related jobs. Through the program I was able to learn about computer design and gain experience through a part-time job with a local computer company. Whenever a new movie came out, I would find out the company which created the special effects for the movie. At the same time, I researched job positions on the Internet. The companies on the Internet suggested universities and degrees on their websites. I planned on studying Computer Science.

    Though I didn't give up my dreams, I continued to pay my attention to daily events. I took part in a large number of activities to broaden my view on life. I worked hard in school to develop my mind. I communicated with people who could give me advice about any problem I might meet along the way. And now, after years of preparation, my hard work is paying off. I know I have succeeded because I put my goals into action.

    When Joanne Morton and Lydia Shaw came across the Boston Public Market, which features only New England businesspersons, they knew they had to stop in. The women, visiting from southeastern Connecticut, always try to buy local. "We always try to support our local farmers and businessmen," says Ms. Shaw. "We're not into big companies," adds Ms. Morton.

    They aren't alone. A great number of Americans continue to be attracted by "local" food and to buy it, according to recent surveys from the International Food Information Council Foundation, the Pew Research Center, and British polling firm Ipsos. But what does it mean to shop local? For some, local is still a matter of geography. For others, it is about supporting their local economy (经济). And for still others, it is about knowing where their food comes from and how it is made, even if it is coffee shipped from a Costa Rican company. In 2008, Congress passed a bill that gave money to support local food. According to the Food, Conservation, and Energy Act, a product that can be considered local has to travel less than 400 miles.

    But Lydia Zepeda, a professor at the University of Wisconsin-Madison, has found the largest agreement about what is local is any product that comes from within an hour's drive. "But is that with or without traffic?" She asks. "What if it crosses state lines?" adds John Hayes, a food science professor at Pennsylvania State University. "A customer might like to buy local to help an old town," he says. "Or maybe it's just because local food tastes better." It is for Kaitlin Bohon. "I taste a difference," she says at the Boston Public Market. For Ms. Bohon, buying local is both about supporting New England business and knowing who grew and handled her food.

    When a leafy plant is under attack, it doesn't sit quietly. Back in 1983, two scientists, Jack Schultz and Ian Baldwin, reported that young maple trees getting bitten by insects send out a particular smell that neighboring plants can get. These chemicals come from the injured parts of the plant and seem to be an alarm. What the plants pump through the air is a mixture of chemicals known as volatile organic compounds, VOCs for short.

    Scientists have found that all kinds of plants give out VOCs when being attacked. It's a plant's way of crying out. But is anyone listening? Apparently. Because we can watch the neighbors react.

    Some plants pump out smelly chemicals to keep insects away. But others do double duty. They pump out perfumes designed to attract different insects who are natural enemies to the attackers. Once they arrive, the tables are turned. The attacker who was lunching now becomes lunch.

    In study after study, it appears that these chemical conversations help the neighbors. The damage is usually more serious on the first plant, but the neighbors, relatively speaking, stay safer because they heard the alarm and knew what to do.

    Does this mean that plants talk to each other? Scientists don't know. Maybe the first plant just made a cry of pain or was sending a message to its own branches, and so, in effect, was talking to itself. Perhaps the neighbors just happened to "overhear" the cry. So information was exchanged, but it wasn't a true, intentional back and forth.

    Charles Darwin, over 150 years ago, imagined a world far busier, noisier and more intimate (亲密的) than the world we can see and hear. Our senses are weak. There's a whole lot going on.

We were on the way from Hutchinson to Chicago for a short spring break. For many years I had wanted to take my family on the train. We all went to Chicago four years ago, and the kids loved it. Chicago is one of my favorite cities, too, so the thought struck me again last fall to ride the train to Chicago. Of course, flying would have been faster. But I don't think flying is easier, especially these days, with all the security and waiting in lines at airports.

Though we were tired in the middle of the night, the kids got on the train with the exhilaration of this adventure. "We're moving," my son William shouted happily with big eyes as the train began to pull away from the Hutchinson station.

I removed my shoes and lay down to try to finish my night's sleep. The sleeper car would have better enabled that, but the ordinary train seats were not too bad. An airline flight is a more miserable experience for me：not enough room, two hours of pain with my knees almost touching my chin, the hard seatback in front cracking my kneecaps (膝盖) with every move of the body planted in front of me. On the train I could almost outstretch all of my 6­foot­2­plus body in the generous legroom.

The journey didn't feel at all as long as it was. We all found the train ride a joy. The car ride would have felt every minute of 13 hours. But on the train you are free to walk around, sit in the observation carriage for a while and enjoy the scenery out the windows, have a nice meal in the dining car, read a book, or play a board game.

In short, the train is all about enjoying the trip, which isn't something I do so much when travelling by airline or by car, when the trip seems more of a mission (任务) to get there than an experience to enjoy along the way.

Chicago offers much to do for a family. This time, getting there was half the fun.