【推荐1】We’ve known for years that plants can see, hear, smell and communicate with chemicals. Now, reported New Scientist, they have been recorded making sounds when stressed.

In a yet-to-be-published study, Itzhak Khait and his team at Tel Aviv University, in Israel, found that tomato and tobacco (烟草) plants can make ultrasonic (超声的) noises. The plants “cry out” due to lack of water, or when their stems (茎) are cut. It’s just too high-pitched (音调高的) for humans to hear.

Microphones placed 10 centimeters away from the plants picked up sounds in the ultrasonic range of 20 to 100 kilohertz (千赫兹). Human hearing usually ranges from 20 hertz to 20 kilohertz. “These findings can change the way we think about the plant kingdom,” they wrote.

On average, “thirsty” tomato plants made 35 sounds an hour, while tobacco plants made 11. When plant stems were cut, tomato plants made an average of 25 sounds in the following hour, and tobacco plants 15. Unstressed plants produced fewer than one sound per hour, on average.

Perhaps most interestingly, different types of stress led to different sounds. The researchers trained a machine-learning model to separate the plants’ sounds from those of the wind, rain and other noises of the greenhouse. In most cases, it correctly identified (辨识) whether the stress was caused by dryness or a cut, based on a sound’s intensity(强度) and frequency. Water-hungry tobacco appears to make louder sounds than cut tobacco, for example. Although Khait and his colleagues only looked at tomato and tobacco plants, they think other plants also make sounds when stressed.

If farmers could hear these sounds, said the team, they could give water to the plants that need it most. As climate change causes more droughts (旱灾), they said this would be important information for farmers. “The sounds that drought-stressed plants make could be used in precision agriculture (精准农业),” said Anne Visscher at the Royal Botanic Gardens, Kew, in the UK.

Khait’s report also suggests that insects and mammals (哺乳动物) can hear the sounds up to 5 meters away and respond. For example, a moth (蛾子) may decide not to lay eggs on a water-stressed plant. Edward Farmer, at the University of Lausanne, Switzerland, is doubtful. He said that the idea of moths listening to plants is “a little too speculative”.

If plants are screaming for fear of their survival, maybe we should be glad we can’t hear them.

【推荐2】Imagine taking to the skies, spreading your arms out and soaring (翱翔) through the clouds. Flying is indeed possible — in your dreams. But no one can control what happens in dreams, right? Wrong. 

Dreams in which you are aware that you are dreaming and can control what happens are called lucid dreams (清醒梦). These dreams are most common during the stage of sleep known as rapid eye movement (REM) sleep.

Lucid dreaming has been referenced (提及) throughout history. It’s mentioned in Greek philosopher Aristotle’s writing, as well as in Egyptian hieroglyphics (象形文字) and in the oral traditions of Australian aborigines (土著). However, it wasn’t until 1975 that British psychologist Keith Hearne was credited as the first person to produce scientific proof that lucid dreams occur. Since then, we have learned much more about this phenomenon. According to a study published in the journal Consciousness and Cognition, 55 percent of people have had a lucid dream at least once in their lifetime, while 23 percent experience lucid dreams once a month or more. 

Though these numbers show that the majority of people don’t have lucid dreams regularly, scientists are developing new technology for those who want to have this experience. For example, Curzio Vasapollo invented a device called ZMax, a headband that can monitor eye movements, body movements and heart rate to help people have a lucid dream.

But why would someone want to have lucid dreams? As it turns out, lucid dreaming can have many benefits. Alix Generous, a young woman suffering from autism (自闭症), said in her TED talk: “I love lucid dreaming because it allows me to be free, without judgment of social and physical consequences.” Also, learning how to have lucid dreams may help those who suffer from nightmares. Through being able to control their actions, they may be able to overcome the cause of their fear.

Lucid dreams may encourage creativity, as well. According to the website Notes Read, those who experience this dream state will find access to “an unbelievable fund of knowledge and inspiration”. For example, British American filmmaker Christopher Nolan took inspiration from his own lucid dreams when he wrote the 2010 sci-fi movie Inception.

Maybe one day, everyone can indulge in (沉浸在) lucid dreams.

【推荐3】The concept of “the body” is closely related to the ideas of “illness” and “health”.     1     The main reasons for the differences are genetic, and the fact that people’s bodies change as they age. However, a huge range of research indicates that there are social factors too.

Poorer people are more likely to eat “unhealthy” foods, to smoke cigarettes and to be employed in repetitive, physically difficult work.     2     That is to say, the physical shapes of bodies are strongly influenced by social factors.

These social factors are also closely linked to emotional wellbeing. People with low or no incomes are more likely to have mental health problems.     3     For example, certain people with mental health issues may be at risk of becoming homeless, just as a person who is homeless may have an increased risk of illnesses such as depression.

    4     Bodies are young or old, short or tall, big or small, weak or strong. Whether these judgements matter and whether they are positive or negative depends on the cultural and historical contexts. The culture, and media, of different societies promote very different valuations of body shapes.     5     Currently, in rich societies the idea of slimness is highly valued, but historically this was different. It is easy for people to feel undervalued because of factors they have no power to change, for example, their age and height. Equally, they can feel pressured into making changes to their appearance when there is a choice, which in some cases can lead to an unhealthy interest in weight loss. Therefore, sociologists are suggesting that we should not just view bodies and minds in biological terms, but also in social terms.

【推荐1】If English means endless new words, difficult grammar and sometimes strange pronunciation, you are wrong. Haven’t you noticed that you have become smarter since you started to learn a language?

According to a new study by a British university, learning a second language can lead to an increase in your brain power. Researchers found that learning other languages changes grey matter. This is the area of the brain which processes information. It is similar to the way that exercise builds muscles. The study also found the effects are greater, the younger people learn a second language.

A team led by Dr. Andrea Mechelli, took a group of Britons who only spoke English. They were compared with a group of “early bilinguals” who had learnt a second language before the age of five, as well as a number of later learners.

Scans showed that grey matter density in the brain was greater in bilinguals than in people without a second language. But the longer a person waited before mastering a new language, the smaller the difference.

“Our findings suggest that the structure of the brain is changed by the experience of learning a second language.” said the scientists. It means that the change itself increases the ability to learn.

Professor Dylan Vaughan Jones of the University of Wales, has researched the link between bilingualism and math skills. “Having two languages gives you two windows on the world and makes the brain more flexible” he said, “You are actually going beyond language and have a better understanding of different ideas.”

The findings were matched in a study of native Italian speakers who had learned English as a second language between the ages of 2 and 34. Reading, writing and comprehension were all tested. The results showed that the younger they started to learn, the better. “Studying a language means you get an entrance to another world,” explained the scientists.

【推荐2】What picture do you have of the future? Will life in the future be better, worse or the same as now? What do you hope about the future?

Futurologists(未来学家) predict that life will probably be very different in 2050 in all the fields of activity, from entertainment to technology. First of all, it seems that TV channels will have disappeared by 2050. Instead, people will choose a program from a “menu” and a computer will send the program directly to the television. By 2050, music, films, programs, newspapers and books will come to us by computer.

In what concerns the environment, water will have become one of our most serious problems. Demand for water will increase ten times between now and 2050 and there could be serious shortages. Some futurologists predict that water could be the cause of war if we don’t act now.

In transport, cars will run on new, clean fuels and they will go very fast. Cars will have computers to control the speed of the car and there won’t be any accidents. Today, many cars have computers that tell drivers exactly where they are. By 2050, the computer will control the car and drive it to your destination.

In the domain(领域)of technology，robots will have replaced people in factories. Many factories already use robots. Big companies prefer robots-they do not ask for pay rises or go on strike, and they work 24 hours a day. By 2050, we will see robots everywhere-in factories, schools, offices, hospitals, shops and homes.

Last but not least, medicine technology will have conquered many diseases. Today scientists have discovered how to control genes. They have already produced clones of animals. By 2050, scientists will be able to produce clones of people and decide how they look, how they behave and how much intelligence they have. Scientists will be able to do these things, but should they?