What makes a gift special? Is it the price you see on the gift receipt? Or is it the look on the recipient's face when they receive it that determines the true value? What gift is worth the most?

    This Christmas I was debating what to give my father. My dad is a hard person to buy for because he never wants anything. I pulled out my phone to read a text message from my mom saying that we were leaving for Christmas shopping for him when I came across a message on my phone that I had locked. The message was from my father. My eyes fell on a photo of a flower taken in Wyoming, and underneath a poem by William Blake. The flower, a lone dandelion standing against the bright blue sky, inspired me. My dad had been reciting those words to me since I was a kid. That may even be the reason why I love writing. I decided that those words would be my gift to my father.

    I called back. I told my mom to go without me and that I already created my gift. I sent the photo of the cream-colored flower to my computer and typed the poem on top of it. As I was arranging the details another poem came to mind. The poem was written by Edgar Allan Poe; my dad recited it as much as he did the other. I typed that out as well and searched online for a background to the words of it. The poem was focused around dreaming, and after searching I found the perfect picture. The image was painted with blues and greens and purples, twisting together to create the theme and wonder of a dream. As I watched both poems passing through the printer, the white paper coloring with words that shaped my childhood, I felt that this was a gift that my father would truly appreciate.

    Christmas soon arrived. The minute I saw the look on my dad's face as he unwrapped those swirling black letters carefully placed in a cheap frame, I knew I had given the perfect gift.

    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 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? 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 the best 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 on their technology, and expect the E-Kaia to go on sale in December 2016.

    Keeping a busy social life among lots of friends may keep people thinner than spending hours doing some exercises, according to scientists. They say that socializing and meeting with friends help increase levels of brown fat in the body which burns calories to produce heat.

    Living in an exciting social environment was found to reduce fat in mice's belly by half over four weeks, even if they ate more.US researchers say that social excitement aids weight loss by turning white fat into brown fat. White fat stores calories and makes us fatter, while brown fat burns energy to produce heat. Turning white fat into brown fat is extremely difficult, normally requiring long-term stay in cold conditions or exciting part of the body's nervous system.

    However, scientists from Ohio State University now think that having a busy social life is an even more effective way of changing white fat into brown fat. The team came up with their theory by studying the effects of various living environments on mice. Those, who lived alongside a greater number of mice, had more space and toys to excite themselves and they lost far more weight over the course of the study than their “couch potato” fellows.

    Study's author, Dr Mattew During whose team's findings appear in the journal Cell Metabolism, said,“I'm still amazed at the degree of fat loss that occurs.” Explaining how new technology had threatened face-to-face socializing, he added,“It's not just a sedentary (久坐的)lifestyle and high calorie foods, but an increasing lack of social activities.” Co-author Dr Lei Cao said,“Loneliness is a potential factor for cancer and death; it's equal to cigarette smoking to a certain extent. Social activities are very vital.”

    The idea of progress started to flower in the 17th century. At that time, many wise thinkers believed that man liberated（解放） by reason would rise to greater heights of achievement. The many expressions of human nature would be the engines of progress: language, business, science, and moral sensibility （道德感）. Unfortunately, most of those engines have failed to bring the desired human progress.

    The modern age has belonged to material progress and its main source has been science. Science gives people huge power to change the world. But can people be trusted to use it always for good? Think of biotechnology and information technology. And it is not just that scientific progress does not deliver the emotional good. People also fear that mankind is failing to manage science properly. The forests are disappearing; the ice is melting; privacy is leaking; life is becoming a depressing march in an ugly world.

    The point is not that science is harmful, but that scientific progress needs to be mapped tidily onto human progress. That relies on moral sensibility in its widest sense. This liberal force offers hope for a better future. The very idea of moral sensibility probably sounds out-of-date. Bur researchers find that people desire a sense of moral purpose which would give life dignity （尊严）. People want to determine how the world works, not always to be determined by it. Moral sensibility is why people will suffer from their beliefs, and why acts of noble self﹣sacrifice are so powerful.

    It is admitted that our moral ideals will never be realized completely. But sometimes, however imperfectly, we can make progress. Human dignity requires the love of ideals for their own sake, but nothing requires that the love be returned.

Human progress is neither guaranteed nor hopeless. Instead, it is up to us.

    Your next Saturday night takeaway could be brought to you by a robot after a major food delivery company announced plans to use automated vehicles to transport meals. Europe's biggest online takeaway food company Just Eat has partnered with Starship Technologies to deliver food with robots on the streets of London later this month. "Nobody has ever done deliveries with land-based robots," said Allan Martinson, the chief operating officer of Starship.

    The robot courier can travel up to 4 miles per hour for about 10 miles. It uses a GPS signal and nine cameras to navigate (确定方向). Instead of a person arriving at their door, customers could find themselves receiving a notification on their phone that says a robot is on its way and a code to unlock the automated courier. "Put the code in, the robot opens up, and there's your food," said David Buttress, chief manager of Just Eat.

    The robot, which has so far been tested in Greenwich, Milton Keynes and Glastonbury, costs £ 1 to transport within 3 miles, compared with the £3 to £6 it costs for a human courier. To date 30 robots have driven nearly 5,000 miles without getting into an accident or finding themselves picked on by passers-by. They have driven in more than 40 cities around the world, including London and Tallinn, Estonia.

    An initial worry was how the public would react to robots. But Martinson said the public has been calm when passing the delivery machine on the streets. "The most surprising reaction has been the lack of reaction," said Martinson.

    Another significant fear was that people would disrupt (扰乱) the robots, or try to steal them and their contents. To prevent this, the robot is fitted with nine cameras, two way audio, and movement sensors that send a warning if it is lifted off the ground. And it opens only with a passcode provided to the customer via a notification. "It's much easier to shoplift than it is to steal a robot," said Martinson.

Crocodiles today look very similar to ones from 200 million years ago. There are also very few species alive today—just 25. Other animals such as lizards (蜥蜴) and birds have achieved a diversity of many thousands of species in the same amount of time or less.

Prehistory also saw types of crocodile we don't see today, including giants as big as dinosaurs, plant-eaters, fast runners and snake-like forms that lived in the sea. The rate of their evolution is generally slow, but occasionally they evolve more quickly because the environment has changed. In particular, their evolution speeds up when the climate is warmer, and their body size increases.

The body size of crocodiles is important because it interacts with how fast animals grow, how much food they need, how big their populations are and how likely they are to become extinct. The limited diversity of crocodiles and their apparent lack of evolution is a result of a slow evolutionary rate. It seems the crocodiles arrived at a body plan that was very efficient and perfect enough that they didn't need to change it in order to survive. This perfection could be one explanation why crocodiles survived Cretaceous period (白垩纪), in which the dinosaurs died out.

Crocodiles generally develop better in warm conditions because they cannot control their body temperature and require warmth from the environment. The climate during the age of dinosaurs was warmer than it is today, and that may explain why there were many more varieties of crocodiles than we see now. Being able to draw energy from the sun means they do not need to eat as much as a warm-blooded animal like a bird or a mammal (哺乳动物).