Research shows that isolation(隔绝，孤立)is bad for us and associated with certain diseases including depression, high blood pressure and heart disease. Yet teenagers seek isolation by using the device of our times—a screen, screens of all kinds. However, in whatever form, screens are addictive, and addictive from an early age. Research has shown that given the chance, six-month-old babies prefer screens to real human faces.

    Hand in hand with this addiction to screens, we are seeing an explosion of teenage mental health problems. Social media claims to be inclusive, keeping you connected. But it's not. It isolates you from real people. Screens have even been described as being poisonous for teenagers.

    Psychologist Jean Twenge, a professor at San Diego State University, believes today's teenagers are “on the edge” of a major mental health crisis and requestes, “do anything that doesn't involve a screen”. The problem is, she claims, children born between 1995 and 2012 have grown up with a smart phone in their hands, and it has “changed every aspect” of their lives. The number of teenagers who actually see their friends frequently has dropped by more than 40% since 2000. In 2015, only 56% of 17-year-old went on a date, down from 85%. Modern teenagers are slower to learn to drive, or earn money and spend more time at home. They're “on their phone, in their room, alone and often depressed”, she says.

    Some critics, however, say we should encourage our children to spend more time online. Robert Hannigan, former director of GCHQ, said in August that Britain is badly short of engineers and computer scientists, and urged children to develop cyber skill to compete in the digital economy.

    I' m not the first to say that social media is inferior to real human contact, and harms mental health. Studies show teens who spend three hours a day online are 35% more likely to suicide(自杀).

    The suicide rate among girls aged 12 to 14 has more than doubled in a decade.

    A “virtual (虚拟的) cocktail” glass that lets you change the flavor (味道) of your drink using your Smartphone has been developed by scientists.

    Offering a customizable (定制的) range of drinks and tastes, the Vocktail can change a glass of water into a cocktail at the press of a button. The world's first technology tricks your brain into thinking it is experiencing a specific flavor by fooling your senses of sight, smell and taste.

    Developed by researchers at the National University of Singapore, the glass' three sensory components are controlled via a Smartphone App. Because the software can combine a number of smells, colors and tastes, the Vocktail can create almost any flavor.

    Developer Nimesha Ranasinghe said: “Our approach is to increase drinks flavor experience by overlaying outer sensory stimuli (刺激物). For example, in the Vocktail we overlay color, taste and smell sensations to create an adjustable flavor experience. Flavor is mainly how we feel food and that is achieved through the use of these senses. Therefore, by changing the color of the drink, using different smells and changing the taste through electricity, we are able to copy the flavor of a drink without it actually changing the liquid.”

    The glass houses three fragrance containers connected to micro-air pumps. The pumps release smell that change your feeling of the drinks, flavor. For example, a lemon fragrance will trick your brain into believing it is tasting lemon-flavored drink.

    On the outside edge of the glass are two electrode strips (电焊条) that send electric pulses into your tongue to stimulate your sense of taste and flavor differs with different pulses.

    It may appear strange to hear that crops are making headlines.But this is no ordinary produce—these fruits and vegetables have been grown in simulated（模拟的）Martian and lunar soils!

    Though the possibility of growing crops in outer space only gained widespread interest after Matt Damon grew potatoes in the movie "The Martian",scientists have been testing the idea for many years.Fresh produce will after all be the key to setting up space colonies（殖民地）.

    Among the pioneers in this effort is a team led by Wieger Wamelink,a scientist at Netherland's Wageningen University.In 2013,they planted fourteen varieties of plants in simulated Martian and lunar soils.Though the "Mars" plants did not bear any produce,they grew better than the "lunar" plants,most of which died shortly after being planted.Lack of vapor in the soil,according to the scientists,might have accounted for the failure.

    The second experiment began in late 2015.The researchers selected the same crops,while this time they used larger containers and added grass to them.In March 2016,their efforts were rewarded with a variety of produce including the vegetable that kept "The Martian" alive: potatoes.

    However,the researchers were still not sure if the produce was safe to eat.That's because the Martian and lunar soils contain heavy metals like lead and arsenic,which do not affect plants but are poisonous to humans.

    After months of testing,earlier this week,the team finally confirmed that the produce was safe for human consumption.Some of the crops even contained lower levels of heavy metals than plants grown in the "ordinary" earth soil.

    To celebrate the success,the scientists held a dinner party that centered ground the crops.While there is no word on how the food tasted,it sure looks delicious.

    When a dog looks at you with big puppy-dog eyes, it's hard for you to go away, and you may speak out “Awww” without hesitation. However, there's a reason why you find a dogs stare so attractive. That sweet stare actually causes the release of a particular hormone, or chemical messenger in the body. This hormone creates feelings of affection in humans. The same thing happens to dogs when people look back at them. Scientists believe this helps people and their four-legged friends bond, or feel connected. Scientists have wondered what causes dogs to lovingly stare at their owners. To find out, a team of researchers from Azabu University in Japan studied 30 owners and their dogs.

    The researchers found that after the pets and their owners spent half an hour together, both showed a rise in oxytocin (催产素). One key role of this hormone in many animals is to promote bonding, like that between a mother and newborn. The increase of oxytocin didn't happen, though, when scientists repeated the experiment with wolves and the humans who had raised them.

    A second experiment also found that if dogs were given oxytocin, they looked at their owners longer. Scientists aren't sure exactly why, but this reaction occurred only with female dogs. Their owners oxytocin levels also rose as a result.

    The result of these experiments might help answer an age-old question: How did the fearsome wolf ancestor of modern dogs turn into man's best friend? Takefumi Kikusui, an animal scientist who worked on the study, thinks that the change happened when dogs first became domestic (驯养的).

    According to Kikusui, there may have been a small group of wild dogs that were naturally friendlier. “Humans are very sensitive to eye contact. By using this special communication tool, the dogs are able to win over our hearts. If they are more likely to make eye contact, it would be easier for them to bond with dog owners,” Kikusui said.

    America is a mobile society. Friendships between Americans can be close and real, yet disappear soon if situations change. Neither side feels hurt by this. Both may exchange Christmas greetings for a year or two, perhaps a few letters for a while — then no more. If the same two people meet again by chance, even years later, they pick up the friendship. This can be quite difficult for us Chinese to understand, because friendships between us flower more slowly but then may become lifelong feelings, extending (延伸) sometimes deeply into both families.

    Americans are ready to receive us foreigners at their homes, share their holidays, and their home life. They will enjoy welcoming us and be pleased if we accept their hospitality (好客) easily.

    Another difficult point for us Chinese to understand Americans is that although they include us warmly in their personal everyday lives, they don't show their politeness to us if it requires a great deal of time. This is usually the opposite of the practice in our country where we may be generous with our time. Sometimes, we, as hosts, will appear at airports even in the middle of the night to meet a friend. We may take days off to act as guides to our foreign friends. The Americans, however, express their welcome usually at homes, but truly can not manage the time to do a great deal with a visitor outside their daily routine. They will probably expect us to get ourselves from the airport to our own hotel by bus. And they expect that we will phone them from there. Once we arrive at their homes, the welcome will be full, warm and real. We will find ourselves treated hospitably.

    For the Americans, it is often considered friendly to invite a friend to their homes than to go to restaurants, except for purely business matters. So accept their hospitality at home!

    People who increased the number of times they chewed their food before swallowing ate less each meal, according to a new study.

    Slow eaters tend to be slimmer. Before the study, the researchers didn't know whether asking people to chew more would change the amount of food they ate. But they found meal sizes became smaller when adults chewed more before swallowing——whether they were slim, normal-weight, overweight or obese.

    “The study proves the benefits of taking time to chew food well,” said dietitian Brown Giggs.

    The participants were asked to eat five pizza rolls and count the number of times they chewed each roll. Researchers did not tell them what exactly was being tested in the study. 47 people went on to finish the study. 10 were slim, 10 were normal-weight, 27 were overweight. Those participants attended three weekly lunchtime test periods. Each day, researchers gave them 60 pizza rolls and told them to eat until they were full. Depending on the period, researchers asked people to chew every bite the same number of times as at their test visit, 50% more or twice as many times.

    Slim participants ate more slowly than normal-weight and overweight participants. Overall, people spent more time eating when they increased the number of times they chewed. The participants rated their appetite (食欲) the same after each meal even though slower chewing reduced how much they ate.

    Researchers noted that the study was conducted under lab conditions, so it's not clear whether it would adapt to normal life. The researchers are now looking to see whether how fast people eat, for example, influences how much they eat. “It takes about 20 minutes for the brain to signal your stomach that you're full,” Brown Riggs said.

    “Fast eaters can eat a large amount of food within that 20-minute period causing more calories, which can lead to being overweight or obesity.”