"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.

    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.

The Domestication （驯化）of Cats

    For centuries, the common view of how domestication had occurred was that prehistoric people, realizing how useful it would be to have animals kept for food, began catching wild animals and breeding （繁殖）them. Over time, by allowing only animals with "tame"（驯养）characteristics to produce their babies, human beings created animals that were less wild and more dependent upon people. Eventually this process led to the domestic farm animals and pets that we know today, having lost their ancient survival skills and natural abilities.

    Recent research suggests that this view of domestication is incomplete. Prehistoric human beings did catch and breed useful wild animals, but specialists in animal behavior now think that domestication was not simply something people did to animals—the animals played an active part in the process. Wolves and wild horses, for example, may have taken the first steps in their own domestication by hanging around human settlements, feeding on people's crops and getting used to human activity. The animals which were not too nervous or fearful to live near people produced their babies that also tolerated humans, making it easier for people to catch and breed them.

    In this version, people succeededin domesticating only animals that had already adapted easily to life around humans. Domestication required an animal that was willing to become domestic. The process was more like a dance with partners than a victory of humans over animals.

    At first glance, the laming of cats seems to fit nicely into this new story of domestication. A traditional theory says that after prehistoric people in Egypt invented agriculture and started farming, rats and mice gathered to feast on their stored grain. Wildcats, in tum, gathered at the same places to hunt and eat the rats and mice. Over time, cats got used to people and people got used to cats. Some studies of wildcats, however, seem to call this theory into question. Wildcats don't share hunting and feeding areas, and they don't live close to people. Experts do not know whether wildcats were partners in their own domestication. They do know that long after people had acquired domestic dogs, sheep and horses, they somehow acquired domestic cats. Gradually they produced animals with increasingly tame qualities.

    Have you ever awakened and felt like you couldn't move? If so, it probably scared you. You may have thought something terrible had happened to you. Actually, many people have this experience on a regular basis. It is called sleep paralysis. Although it sounds scary, it is normal.

    Sleep paralysis happens when a person is falling asleep or waking up. As the person falls asleep, his or her body slowly relaxes. Usually the person's mind relaxes at the same time, but occasionally the mind stays awake longer than the body. As a result, the person can be conscious, or aware, but have trouble moving or speaking. Sleep paralysis can also occur as you wake up. Fortunately, the condition rarely lasts for more than a few seconds. Movement and speech soon return to normal.

    Some people report unusual experiences during sleep paralysis. They may hear, see, or feel things that don't exist. At one time, people thought that ghosts or monsters had entered the room and were holding them down, keeping them from moving. Science has helped us understand that such visions are actually a part of sleep paralysis. Now we know that getting too little sleep, taking certain medications, and changing your sleep schedule can cause sleep paralysis. This condition can be scary if you, but it's just a trick that your mind is playing on your body.

    A person can use all five senses while spending time with dolphins. We can see them play in the waves, hear them call, and feel their skin. Dolphins can sense you, too, but not in all the same ways. They have good eyesight, for example, but no sense of smell. Sensory biologists try to understand connections between animal behaviors and the senses. One team of these scientists recently made an unexpected discovery about certain dolphins.

    The researchers found that Guiana dolphins can detect electric fields, an ability that may help them find fish to eat. The secret to this newly found sense, say the scientists, is hidden in the dolphins' snouts (口鼻部).

    "We were really surprised to find this in the dolphin. Nobody had expected it," said Wolf Hanke, who led the new dolphin study.

    Hanke and his team suspected the dolphin's electro－sense might have something to do with small dimples (酒窝) on the animal's snout. "We thought they must have some functions," Hank said. To find out for certain, his team studied two Guiana dolphins.

    The scientists first studied the dimples of a 29－year－old dolphin that had died of natural causes. Under a microscope, the dimples looked familiar: they were similar to the sensors used by other animals to detect electric fields.

    Next, Hanke and his team tested a live dolphin, a 28－year－old named Paco, to see if he could recognize an electric field. They taught Paco to swim close to a device that could create a weak electric field in the water. Then the team taught Paco to swim away from the device if he detected any changes. When the scientists created an electric field, Paco swam away—showing that he knew something had changed. When there was no electric field, Paco stayed there. When Paco's snout was covered in plastic, he didn't react to the electric field.

    Paco's behavior told the scientists that the dolphin used his snout to detect the tiny electric field. "This is a major breakthrough," Peter Madsen, a sensory biologist, said.

Long ago, poets in Japan listened, watched, and caught the beauty of the earth's songs like the raindrops. They did this with the tiniest poems in the world, called haiku. A haiku is a poem that is just three lines and seventeen syllables long. And the poets who wrote them watched and listened, not only with their eyes and ears, but also with their hearts!

In their haiku, the early Japanese poets caught the colours, sounds, and beauties of the seasons of the year. They sang of their islands' beauties. Their miniature poems were not meant to fully describe a scene or to explain it but rather were a flash impression. 

Interestingly enough, Japanese poetry has had a long and colourful history. In the prehaiku period in the early eighth century, Japanese poets wrote katauta, poems in a question-and-answer form, using two people. Each three-line verse contained about seventeen syllables that could be delivered easily in one breath—just as one would naturally ask or answer a question. This has remained the basic pattern for traditional Japanese poetry throughout the centuries. 

Another form that appeared was the tanka, which contained five lines and thirty-one syllables(5, 7, 5, 7, 7), written by either one or two persons. From that evolved(逐步形成) the renga, which contained more than one verse, or link. Written by three or more people, it could have as many as 100 links! The first verse of the renga introduced a subject. It had three lines and was called hokku, or starting verse. Renga parties became a great pleasure. 

Around 1450, haikai no renga became popular. This style of linked verse contained puns (双关) and was humorous and amusing. The opening three lines were still called a hokku, and from haikai and hokku the term haiku evolved.