【推荐1】A chemical signal from the liver, caused by exercise, helps elderly mice keep their brains sharp, suggests a recent study. Understanding this liver — to — brain signal may help scientists develop a drug that benefits the brain the way exercise does.

Lots of studies have shown that exercise helps the brain, decreasing the memory declines that come with old age. Scientists have long looked for ways to get elderly people unable to work out to have the same benefits.

Saul Villeda, a neuroscientist at the University of California. and his colleagues focused on the fitness effects of blood from young mice. They injected inactive elderly mice with plasma（血浆）from elderly mice that had regularly exercised. After eight injections over 24 days, the former performed better on memory tasks than elderly mice that received no injections.

Examining the plasma of exercised mice showed an abundance of proteins（蛋白质） produced by the liver. The researchers closely studied one of these liver proteins, called GPLD1. GPLD1 is an enzyme （.酶）— It lets other proteins off the outsides of cells, releasing those proteins to go do other jobs. "Getting the liver to produce this one enzyme can actually gain all the beneficial effects we see in the brain with exercise,” Villeda says.

But the role of GPLD1 is far from settled, says Irina Conboy, a researcher at the University of California. There's evidence that GPLD1 levels are higher in people with diabetes（糖尿病）,she points out, indicating that the protein may have negative effects. “And different experiments suggest that GPLD1 levels might actually fall in response to certain kinds of exercise in rats with diabetes.” she notes. "We know for sure that exercise is good for you, and that this protein is present in the blood. But whether it's good or bad, no one knows for sure. ”

【推荐2】Researchers from Sejong University in South Korea have created a new laser (激光) charging system that can transmit power using infrared (红外线的) light over up to 30 meters (98.4 feet), offering a safe alternative to corded charging for mobile devices and powering the Internet devices spread throughout an area. The system could deliver 400 milliwatts of power across this distance, enough to charge sensors but not quite enough to charge mobile devices yet.

Wireless power transmission has been achieved over greater distances, but transmitting power safely across meter-scale distances has brought challenges. The researchers overcame this with a technique known as distributed laser -charging, separating the laser’s transmitter and receiver, creating a laser cavity (腔) between them through which light-based power can be transmitted. While most other approaches require the receiving device to be in a special charging place or to be stationary, distributed laser charging enables self-alignment without tracking processes as long as the transmitter and receiver are in the line of sight of each other.

When a device interrupts the line of sight, the system automatically changes to a power-safe mode that allows it to deliver power wirelessly and safely. It also automatically shifts to a safe low power delivery mode if an object or a person blocks the line of sight.

“The ability to power devices wirelessly could eliminate the need to carry around power cables for our phones or tablets. Using the laser charging system to replace power cords in factories could save on maintenance and replacement costs. This could be particularly useful in rough environments where electrical connections can cause interference or pose a fire risk,” said research team leader Jinyong Ha.

【推荐3】Is it shi(是) or si(斯) in the sentence “Thus when Heaven is about to confer a great office on any man(故天将降大任于是/斯人也)…”? Not long ago, people had a heated discussion online about this. Most people “clearly remember” that it’s si, while their childhood textbooks say it’s shi.

It shows how unreliable(不可靠的) our memory can be. According to US psychologist Faith Brynie, memories can be influenced by imagination, belief and time. Many studies have proven that “feeling certain” about a memory sometimes has nothing to do with the facts.

Attitudes and beliefs change our memory.

Scientists at Cornell University, US, told college students a story about a man who walked out without paying a restaurant bill. The first group was told that the man “liked to steal”. The second group was told that he left because he got an emergency(紧急的) phone call.

One week later the first group remembered a higher bill-10 to 25 percent more than the bill actually was. The second group remembered a lower bill. The study showed that how we expect or believe things to happen can distort(扭曲) our memories.

Remembering things that never happened

In another experiment(实验), people watched a film and were asked: “How fast was the white car going when it passed the barn(谷仓) while traveling along the country road?”Actually there was no barn in the film. But about 20 percent of the students said they had seen the barn. Northwestern University scientist Kenneth Paller said that parts of the brain for really seeing an object and imagining an object overlap(重叠). So imagination after getting a hint(暗示) could leave a memory trace(痕迹) in the brain.

Si or shi

In the case of si or shi, some people said that si sounds more like ancient Chinese. That’s why most people relate it to the ancient classic. On the Internet, the version(版本) of si is also more widespread than shi, giving people a wrong hint.

【推荐2】Flash fiction is a name for short stories that are kept within a specific word or character limit, usually up to 1,500 words.    1    . It’s about finding clever ways to keep as much detail as possible about the plot, characters and setting but in the fewest words possible. Use these four top tips to help you write your own fascinating flash fiction.

●    2    

When planning a flash fiction story you first need to decide what are the important parts of the story that the reader just cannot miss. This might be a few moments from the beginning, middle and end. Once you have these, then any extra detail can either be cutaway or added in—if it makes the story better and the word limit allows.

●Develop characters using adverbs

Good flash fiction has well-developed characters who have personalities and faults. You can takeout long descriptions of your characters and replace them with the occasional adverb to help the reader understand the characters’ movements and behaviour. Adverbs are words that describe verbs.    3    .Examples of adverbs include, “The prince stared angrily and marched awkwardly back to his horse.”

●Use clauses to add colour and detail

Clauses add detail to sentences without adding too many words.    4    .This is a section of a sentence starting with which, who, when, where, etc. For example, “The air, which smelt of oranges...” Be careful not to make sentences too long, though, and takeout any clauses that don’t add anything to the story.

●Combine your sentences

    5    .For example: Mary was upset she had school and took her shoes off. She slumped on the sofa and flicked on the TV. It was going to be a long day and she was nervous about meeting the new head teacher. This becomes; Mary slumped in front of the TV, took off her shoes and decided she was too nervous for school.