Nine years ago, after Leo had died, people said to me. "I never knew he was your stepfather." You see, I never called him that. At first, he was no one special in my life. Then he became my friend. In time, I felt he was also my father.

    Leo married my mother when I was eleven. Two years later we moved into a house in a new suburban development, where we put down roots. At first our lawn was just a mud with wild grass, but Leo saw bright possibilities. "We'll plant trees there to give us shade as well as some flowers," he said. And just these little touches made our house different from all the others. More important, a real family was forming. Leo was becoming a full-time parent, and I was learning what it meant to have a father.

    Weekday mornings when the weather was bad, Leo often drove me to school. Having a father drop you off may have been something my classmates took for granted, but I always thought it was wonderful. Saturday mornings, we went to the hardware (计算机硬件) shop, then stepped into the five-and-ten, buying a sports magazine or something else. Some people might think that doing shopping together is nothing special, but I, who had ever before spent my childhood watching other families do their everyday activities, experienced them now with extreme delight. Looking back, I realized that Leo gave me what I needed most—the experience of doing ordinary things together as a family.

    Soon after we moved to the suburbs, one of our new neighbors introduced herself to me. She had already met my mother and Leo. "You know," she said, "you look just like your father." I knew she was just making a conversation--but even so... "Thank you", I said. Why tell her anything different?

    With only about 1,000 pandas left in the world, China is desperately trying to clone the animal and save the endangered species. That's a move similar to what Texas A & M University researchers have been undertaking for the past five years in a project called "Noah's Ark".

    Noah's Ark is aimed at collecting eggs, embryos (胚胎), semen and DNA of endangered animals and storing them in liquid nitrogen. If certain species should become extinct, Dr. Duane Kraemer, a professor in Texas A & M's College of Veterinary Medicine, says there would be enough of the basic building blocks to reintroduce the species in the future.

    It is estimated that as many as 2,000 species of mammals, birds, reptiles will become extinct in over 100 years. The panda, native only to China, is in danger of becoming extinct in the next 25 years.

    This week, Chinese scientists said they grew an embryo by introducing cells from a dead female panda into the egg cells of a Japanese white rabbit. They are now trying to implant the embryo into a host animal. The entire procedure could take from three to five years to complete.

    "The nuclear transfer (核子移植) of one species to another is not easy, and the lack of available panda eggs could be a major problem," Kraemer believes. "They will probably have to do several hundred transfers to result in one pregnancy. It takes a long time and it's difficult, but this could be groundbreaking science if it works. They are certainly not putting any live pandas at risk, so it is worth the effort," adds Kraemer, who is one of the leaders of the Project at Texas A & M, the first-ever attempt at cloning a dog.

    "They are trying to do something that's never been done, and this is very similar to our work in Noah's Ark. We're both trying to save animals that face extinction. I certainly appreciate their effort and there's a lot we can learn from what they are attempting to do. It's a research that is very much needed."

    "Have a nice day！" may be a pleasant gesture or a meaningless expression. When my friend Maxie says "Have a nice day" with a smile, I know she sincerely cares about what happens to me. I feel loved and safe since another person cares about me and wishes me well.

    "Have a nice day. Next！" This version of the expression is spoken by a salesgirl at the supermarket who is rushing me and my groceries out the door. The words come out in the same tone (腔调) with a fixed procedure. They are spoken at me, not to me. Obviously, the concern for my day and everyone else's is the management's attempt to increase business.

    The expression is one of those behaviors that help people get along with each other. Sometimes it indicates the end of a meeting. As soon as you hear it, you know the meeting is at an end. Sometimes the expression saves us when we don't know what to say. "Oh, you just had a tooth out? I'm terribly sorry, but have a nice day. "

    The expression can be pleasant. If a stranger says "Have a nice day" to you, you may find it heart­warming because someone you don't know has tried to be nice to you.

    Although the use of the expression is an insincere, meaningless social custom at times, there is nothing wrong with the sentence except that it is a little uninteresting. The salesgirl, the waitress, the teacher, and all the countless others who speak it without thinking may not really care about my day. But in a strange and comfortable way, it's nice to know they care enough to pretend they care when they really don't care all that much. While the expression may not often be sincere, it is always spoken. The point is that people say it all the time when they like.

    You have heard the words “that which does not kill you makes you stronger”. I have found it true. But I also believe in the philosophy that we are not defined (定义) by what happens to us, but by what we do when things happen to us.

    Some friends think we have had far more than our share of bad things occur, but I don't think bad things are shared. They are events that occur as the result of many aspects, sometimes far past our control or even knowledge of them. I am also a firm believer in the laws of unintended consequences — one event causes things that are quite unexpected, sometimes positive, sometimes not.

    So as I considered the question of “What motivates me?” and sought an answer, it struck me that I simply refuse to be defeated. I won't let life or events tear me down to the point at which I am no longer me, or simply stop being.

    In 2008, I battled three types of cancer, had four cancer operations, the firm I worked for closed without notice, my wife was in a horrible car accident, got laid off from her company, the economy devastated our life savings, … and that was for starters.

    We also lost two family members and my closest friend. He was the last person I would expect to pass away out of our friends. But a disease took hold of him 9 years earlier. His memorial service was filled with love, and many of us told about his joy of life, humor, his achievements, and the challenges he had overcome in his life — which were many and painful. He would not be defeated in his life either.

    Today, my wife and I are hand-in-hand, continuing trying to live our lives with dignity, although living it differently from the end of 2007.

    It is becoming increasingly important for researchers to closely monitor our ocean life. However, observing sea creatures up close is almost impossible since human presence scares them. Now, thanks to The Soft Robotic Fish, also known as SoFi, researchers may be able to keep a close eye on the sea creatures.

    Built by MIT Computer Science and Artificial Intelligence Laboratory (CSAIL), the white re- mote-controlled robot resembles the real fish, complete with a tail that waves from side to side. Though not the first autonomous underwater vehicle (AUV) created to monitor the ocean, SoFi settles many of the problems that have blocked the usefulness of the previous robot fish.

    Previous AUVs have had to be linked to boats because radio frequency communications don't work well underwater. To overcome the problem, Director of the CSALL Daniela Rus and her team used sound waves. The technology can travel greater distances allowing divers to pilot SoFi from up to 50 feet away.

    Also limiting the usefulness of traditional AUVs is the risk of collision. With the outside made of soft silicone (硅树脂) rubber and flexible plastic that keeps its inbuilt electronics dry, SoFi poses no such danger. "Collision avoidance often leads to unnecessary movement, since the robot has to settle for a collision-free path", says Rus. "In contrast, a SoFi robot is not only more likely to survive a collision but also could use it as information to form a more workable movement plan next time around."

    During test dives, SoFi moved alongside the ocean life at depths of 50 feet for up to 40 minutes at a time, taking photos and making videos. The researchers say sometimes the fish would swim a- longside the strange-looking robot-fish out of curiosity, while at other times they took no notice of its existence.

    While SoFi presently only records video, future versions will include sensors. The researchers also hope to make it more autonomous. "We imagine someday it might help us uncover more secrets from the amazing underwater world that we know so little about," says Rus.

    Scientists recently discovered three tyrannosaur (霸王龙) trackways in Canada. The trackways suggest the meat eaters traveled and hunted in groups. The 70-million-year- old footprints are the first tyrannosaur trackways ever found.

    Tyrannosaurs were a type of meat-eating dinosaur that included the strong Tyrannosaurus rex and Albertosaurus. “Groups of tyrannosaurs may have stuck together as a group to increase their chances of bringing down animals and individually surviving,” study coauthor Richard McCrea says. He works for Canada's Peace Region Paleontology Research Centre. It's believed that tyrannosaurs were solitary creatures. The newly discovered trackways could change the way scientists look at these frightening beasts.

    Trackways can uncover a lot about the social behavior of a species. Unfortunately, very few tyrannosaur footprints have ever been found, and until recently, the only ones known were single prints discovered in Mongolia, the western U.S., and western Canada. But in October 2011, a hunting guide named Aaron Fredlund found two tyrannosaur track marks near Tumbler Ridge, an area in the foothills of the Canadian Rockies. Over the next year, McCrea and his team searched the site and found the remaining trackways.

    The footprints are at about the same depth, which suggests the tyrannosaurs moved through the area at the same time. Impressions of the dinosaurs' rough skin are even visible in the prints. The prints are also in near-perfect condition. That's because the ground had a high clay (黏土 ) content when the dinosaurs walked through the area. The land was later covered by a thick layer of volcanic ash, which kept the marks intact (完整). "This is the most ideal situation you could ask for," McCrea says.

    Researchers aren't sure of the exact species of tyrannosaur that left the prints. But the historic findings show a great deal about how the beasts moved and behaved. “We have extremely convincing evidence that tyrannosaurs traveled in groups,” says McCrea. "This is probably the most important evidence to come out to date on that topic."