I'm part of the Roots & Shoots program founded by Dr. Jane Goodall. The program is intended to make and promote positive changes in the world. As Dr. Goodall says, "What you do makes a difference, and you have to decide what kind of difference you want to make."

    In Bulgaria, where I live, homeless dogs are everywhere. Many people here turn a blind eye to them. But I cannot ignore the life of a street dog whenever I see one wandering in the street, looking for something to eat. That's why I'm no longer a food waster. When I see wasted food, I always think of a hungry dog climbing to garbage bins, searching for food that people have thrown there. When eating in a restaurant, I'm not afraid to take leftover food to feed stray cats or dogs.

    A week ago, I saw a homeless dog around the garbage bins. Immediately I knelt down, spoke to her softly and ran my hands over her. I could see that she had had puppies. I couldn't imagine how she could have been able to care for them. Hours earlier, I'd bagged up a plate of leftover fish. As I unwrapped it, she wagged her tail and sniffed at it. She ate all the fish in no time.

    It's sad, isn't it? I can't understand why many of us waste so much and think little of it. These homeless animals have taught me that food is precious. Even when I don't have leftovers with me, I'll take the time to get something from the grocery store to feed them.

I know my power is small, so I hope that next time you see wasted food, do turn it into worthy food. You have the power to save a life!

French surgeons have performed what they said on Wednesday was the world's first partial face transplant（移植）— giving a new nose, chin and lips to a woman attacked by a dog.

    Specialists from two French hospitals carried out the operation on a 38-year-old woman on Sunday in the northern city of Amiens by taking the face from a brain-dead woman, who had hanged herself just hours before the operation. Her family agreed on the operation.

    “The patient is in an excellent state and the transplant looks normal,” the hospitals said in a brief statement after waiting three days to announce the pioneering surgery.

    The woman had been left without a nose and lips after the dog attacked her last May, and was unable to talk or chew properly. Such injuries are “extremely difficult, if not impossible” to repair using normal surgical techniques, the statement said.

    The statement did not say what the woman would look like when she had fully recovered, but medical experts said she was unlikely to resemble the woman who had been the source of her new face.

    The operation was led by Jean-Michel Dubernard, a specialist from a hospital in Lyon who has also carried out hand transplants.

    Skin transplants have long been used to treat burns and other injuries, but operations around the mouth and nose have been considered very difficult because of the area's high sensitivity（敏感） to foreign tissue.

    Teams in France, the United States and Britain had been developing techniques to make face transplants a reality

    There was a short-term risk for the patient if blood vessels became blocked, a medium-term danger of her body rejecting the new skin and a long-term possibility that the drugs used could cause cancers.

    Experts say that although such medical advances should be celebrated, the transplant had thrown up moral（道德的）and ethical(伦理的)issues. Little is known about the psychological effect of three transplant.

    Tibetan people are friendly and easy to get along with. However, Tibetans have different ways of behavior in many aspects due to their unique culture and religion. Be sure to respect local customs and be polite.

    Don't enter a monastery without permission. Don't smoke in monasteries. Don't touch Buddha statues, religious objects or prayer flags. Walk around monasteries (寺院), temples, dagobas, Mongolian cairns (Mani piles) and other religious structures in clockwise order with the exception of the Bon sites.

    Don t step on the threshold when entering a tent, house, or monastery. Don't touch the head of a Tibetan. The head is considered as a sacred part of the body. Remember to cross your legs when you are asked to have a seat. Don't stretch your legs with feet pointing to others.

    Don't drive away or hurt eagles. Eagles are considered holy birds in the hearts of Tibetan people. Don't disturb or injure cows or sheep with red, green or yellow ribbons because they are Tibetan sacrifice to worship gods.

    Don't take photos without permission. You'd better ask for permission before taking pictures of Tibetan people. Most Tibetan monasteries are not allowed to take pictures or you need to pay.

    Tibetan people are getting more used to habits of foreigners and being more tolerant due to rapidly developing tourism in Tibet. However, we still hope you can show respect to Tibetan traditions and behave well since their unique lifestyle is part of the charm of Tibet.

    These days, I walk down the steps leading toward the south end of the All England Club in Wimbledon, and still look for the Crow's Nest, a small green observation tower with an outer ladder that I used to climb on for a wide view of the grounds, but which has since been knocked down.

    The Crow's Nest was a particularly useful point, because it allowed a tennis writer to keep track of the action on as many as 10 outside courts at a time. At days end, reporters from different nations would share notes on what they had observed all over the grounds.

    Twenty-seven years later, the press room has touch screens that allow us to watch live videos from any court, and even go back to watch key moments in key matches long after they have finished. You could cover Wimbledon without leaving your seat. But that is a bit like spending all your time ordering room service and looking up fun facts on Wikipedia.

    More than at any other tennis tournament, there is also an appetite for stories that deal with the setting, the history and the traditions.

    If they change the price of the fish tacos (鱼肉卷饼) at the United States Open, it's not a story. If they change the price of the strawberries and cream, the signature treat at Wimbledon. It's time to email your editor using capital letters.

    The new retractable (可伸缩的) roof was put in place in 2009. Until then, you always had to have a rainy-day story in your notebook because there were no guarantees any matches would be played. Now tennis is a sure thing on Centre Court, which has made tennis reporters a bit less creative. But at least it guarantees us daily access to the most atmospheric place in the sport.

    So much has changed, but Centre Court remains true to its original spirit: more a theater than a stadium. Catching that feeling is part of covering Wimbledon, too.

    As free as they make us, mobile phones still need to stay close to a power source. Soon that may change with "green" power.

    Three Chilean students got the idea for a plant-powered device(装置) to charge（使……充电） their cellphones, while sitting in their school's outdoor courtyard during a break from exams, with dead mobile phones. Then, one of them had an "aha" moment.

    “It occurred to Camila to say about plants,” said inventor Evelyn Aravena. “'Why don't you have a socket, if there are so many plants? 'After that, we thought, 'why don't they have a charging outlet（插座）? Because there are so many plants and living things that have the potential to produce energy, why not?'”

    Their invention—a small biological circuit called E-Kaia—uses the energy plants to produce during photosynthesis(光合作用). A plant uses only a small part of that energy and the rest goes into the soil, and that's where the E-Kaia collects it. The device plugs into the ground and then into your phone.

    "It's the most amazing project I've ever seen in my life, plain and simple. They brought this original model, and it worked — and that's when it all changed, at least from my personal point of view and I began to support them." said Mauricio Cifuentes.

    The device solved two problems for the engineering students — they needed an idea for a class project, and an outlet to plug in their phones.

    "Looking for a place to charge the notebook, which had no power, and the mobile phones, we weren't able to find anything because all the other students were in the same state of madness trying to find a place to charge their devices," said Aravena.

    But plants are everywhere, and the bio－circuit makes good use of their excess(过多的) power.

    The E-Kaia doesn't carry much charge but it's powerful enough to completely recharge a mobile phone in less than two hours.

    The student inventors have applied for patents（专利） on their technology, and expect the E-Kaia to go on sale in the near future.

    Consumer electronics once again topped the list of the most wanted gifts this holiday season.

    "Seventy-six percent of consumers who plan to buy holiday gifts say that they will spend money or buy at least one technology product; definitely a solid vote of confidence for technology."

    Steve Koenig is with the Consumer Electronics Association. He says the group's latest research also shows that Americans this year are spending more on technology products. "Here in 2012, $252 on average the technology spend for consumers this year."

    From tablet computers to smart phones, American shoppers have been lining up to get the newest and coolest electronic devices on the market. There are more choices today than ever before. "It's kind of hard to make a decision."

    Tablet computers are one of the best-selling products this year. Brian Tong is Senior Editor of CNET.com. The website reports on tech news and examines the latest electronic products. He says the Apple iPad Mini is one of the most popular tablets. Its starting price is $329. One of Apple's biggest competitors is the Google Nexus 7. It starts at $199.

    "Its hardware is more powerful than what's in the iPad Mini, but also it offers you a lot of things like maps that work better than Apple's maps.

    But Brian Tong says there is one reason why people may like the iPad Mini more than the Nexus 7. "If you just want to read books and surf the Internet, you don't really need to get an iPad Mini, but if you want the largest robust group of apps (应用软件) that's where the iPad and Apple's ecosystem shines the most."

    Elman Chacon is with the electronics store Best Buy. He says another hot product this season is smart cameras. They connect to the Internet through Wi-Fi. This makes it easy for users to email or upload photographs directly from the camera." You can literally take a picture and upload it into your Facebook in a matter of seconds. These things are pretty cool because they do a lot of things."

    Streaming media boxes also connect to the Internet. People are able to watch web content such as movies and YouTube videos on their televisions. Another popular item is wireless speaker systems. The newest ones work with any device that has Bluetooth technology, including smart phones, laptops and tablets.