By trying to tickle(挠痒痒) rats and recording how their nerve cells respond, Shimpei Ishiyama and his adviser are discovering a mystery that has puzzled thinkers since Aristotle expected that humans, given their thin skin and unique ability to laugh, were the only ticklish animals.

    It turns out that Aristotle was wrong. In their study published on Thursday, Ishiyama and his adviser Michael Brecht found that rats squeaked and jumped with pleasure when tickled on their backs and bellies. These signs of joy changed according to their moods. And for the first time, they discovered a special group of nerve cells. These nerve cells made this feeling so powerful that it causes an individual being tickled to lose control.

    To make sure that he had indeed found a place in the brain where tickling was processed, Ishiyama then stimulated that area with electrical currents. The rats began to jump like rabbits and sing like birds.

    “It's truly ground-breaking,” said Jeffrey Burgdorf, a neuroscientist at Northwestern University who reviewed the paper. “It takes the study of emotion to a new level.”

    Burgdorf has played a central role in our understanding of animal tickling. He was part of a team that first noticed, in the late 1990s, that rats made special noises when they were experiencing social pleasure. Others had already noted that rats repeatedly made short and high sounds during meals. But the lab where Burgdorf worked noticed that they emitted similar sounds while playing. And so one day, the senior scientist in the lab said, “Let's go and tickle some rats.” They quickly found that those cries of pleasure doubled.

    “The authors have been very adventurous,” said Daniel O'Connor, a neuroscientist at Johns Hopkins University who studies touch. To him, that finding was very surprising.

    “Why does the world literally feel different when you are stressed out?” he said. “This is the first step towards answering that question. It gives us a way to approach it with experimental rigor(严谨).”

Ways to make a great first impression

    You've heard it a million times already, but it really does take but a few seconds to make that all-important first impression（印象）. Here are some easy ways for you to impress your classmates or teachers.

     {#blank#}1{#/blank#}

    Before you shake hands with somebody, make sure that your hands are clean. The handshake should not be too strong or weak. Most people use their right hands, unless they have a reason to use the left. {#blank#}2{#/blank#}

    Be on time

    When meeting someone for the first time, arriving on time is as important as breathing. You may have an excuse, but that will leave the person who hardly knows you with a bad impression.{#blank#}3{#/blank#} It's better to be hanging around the place than be stuck in traffic.

    Introduce yourself and ask for names

Make sure you properly introduce yourself. Ask for their names in a polite way. {#blank#}4{#/blank#} This will increase the chances of their remembering your name in the future. Always remember to stand up when greeting someone and be sure to introduce them to anyone you're with.

    Make good conversation

To get the most out of your discussion, try to find something common between the two of you.

    {#blank#}5{#/blank#} A person will feel more comfortable with someone they can relate to（产生共鸣）.

A. Use body language

B. Have a proper handshake

C. Repeat the name and use it later in conversation.

D. As a general rule, plan to arrive about 30 minutes early.

E. It could be a similar taste in clothes or a common hobby.

F. You'll be in serious trouble if you leave them with a bad impression.

G. However, don't have your left hand in your pocket because this appears impolite.                         

    A lifetime of active exercise will let you keep the body of a 20-year-old well into your 70s, scientists have found.

    The physical decline (衰退) thought to be an unavoidable part of ageing is actually the result of not exercising enough, according to the research, which found that regular cyclists kept the muscles, lungs, and even the immune system (免疫系统) of people years younger. Besides, many serious health problems could be prevented if people became more active, researchers insist.

    Janet Lord, a leading researcher, said, “Our findings prove the false belief that ageing automatically makes us weaker. We now have strong evidence that encouraging people to do regular exercise throughout their lives can solve the problem that we are living longer but not healthier.”

    She looked at 125 cyclists aged 55 to 79 who had been exercising regularly for 25 years and compared them with 75 ordinary people of a similar age and 55 people aged 20 to 36. On a series of physical measures, the cyclists showed no difference from people much younger in their immune systems and making T cells.

    Now Professor Lord aims to discover how much exercise people need to do to stay young. “You needn't work out a lot. It may be intensity (强度) that helps—like going up and down the stairs ten times a day.”

    While there is no magic method of staying mentally and physically fit in later life, the benefits of keeping active can never be ignored, whatever your age or state of health.

    Robots come in many shapes and sizes. But most have one thing in common. They are built to help people. Lately engineers have been developing new kinds of humanoid robots. These high-tech machines are designed to lend a hand everywhere from hotels to disaster areas.

    "Robots help people by making their lives easier, safer, and more fun," says engineer Omar Abdelwahed.

    Since November, a robot named pepper has been on the job at the Mandarin Oriental hotel in Las Vegas, Nevada. When guests have questions or need directions, they can ask Pepper. They can also use the robot's touch screen to find the information they need. Pepper is able to talk with guests and entertain them with stories too. It can even tell what kind of mood they are in.

    "Pepper provides our guests with information in an exciting and new way," says hotel manager Donald Bowman.

    For a kid, being in the hospital can be boring and even scary. But a small robot called NAO is helping to make hospital stays easier. It was designed to keep people company.

    A Tennessee doctor named Phil Parker bought a NAO robot three years ago. He programmed it to talk to and play with young patients. He brings it to hospitals to help sick kids. When kids get medical tests, NAO explains what is going on. The robots also reads to kids and plays games with them like rock, paper, scissors.

    "The robot gets many kids to smile for the first time since they've been in the hospital," Parker says.

    Other robots are being developed to help in places where it's hard or risky for people to go. For example, disaster areas can be full of rubble and other dangers. Engineers in Japan are building a robot called E2-DR to go into those areas and search for people who are hurt.

    The streets of Stockholm may be cold and snowy during winter, but it is one of the world's hottest startup(创业) centers and a good choice for people with talent worldwide.

    Once the snow melts(融化) in early spring, the city is among the greenest in the world. Two thirds of Stockholm is made up of either water or parks, and locals make it the first thing to enjoy these peaceful surroundings. Less than l% of Swedish employees work more than 50 hours per week.

    The quality of life is important. New parents are given 480 days of leave to look after their babies, while childcare is heavily supported in various sides. Little wonder that Sweden was rated the best location in the world for family life. Adam Webb, 34, a British businessman and father-of-one, said, "Everything is set towards helping parents, from giving dads time off on almost full pay to free bus rides for anyone with a baby carriage."

    Stockholm is also proud of what Vogue magazine recently ranked as Europe's coolest neighborhood. On the island of Sodermalm, just south of the city centre, independent record stores still make money, while plenty of cafes offer a taste for Scandinavia's love affairs with timeless style.

    Many major international companies, including H&M and Ericsson, offer expats(外来者) accommodation for the first three months of their contracts(合同) in Stockholm. But other foreigners arriving in the city are left to battle with a unique property market and a shortage of apartments. More than a third of Swedes live in rented housing, half of which is owned by local governments or state rental companies. If you're lucky enough to get a firsthand contract for this kind of accommodation, it is yours for life. Expats are welcome to join the queue, but in Stockholm they will find around half a million locals in front of them and an average wait of nine years.

    "Finding a place to live is the single biggest challenge when moving to Stockholm, but there is a lot going on to try and solve the problem," said Julika Lamberth from Stockholm Business Region, a state-funded company working to increase investment in the city.

    A Japanese telecom company has designed a robot that it says has emotions (情绪). But rather than run in fear from it, we've welcomed it into our homes: Pepper, the "emotional robots" sold out within a minute of going on sale.

    Created by Aldebaran Robotics and Japanese mobile giant SoftBaok, Pepper went on sale to the general public in Japan on June 20. It is "the first humanoid (类人的) robot designed to live with humans, " Aldebaran says on its website. Pepper costs about $ 1, 600. And like all good mobile products, there's a $ 120 per month data fee, as well as an $80 per month damage insurance fee. According to a news report, Pepper can pick up on human emotions and create his own using a "multi - layer neural (神经的) network." Pepper's touch sensors and cameras are said to influence its mood, which is displayed on the tablet-sized screen on its chest.

    Pepper will sigh when unhappy, and can go around your house recording your family's daily activity. Aldebaran says Pepper can feel "joy, surprise, anger, doubt and sadness," but it doesn't say how strongly it can feel these emotions. What happens when Pepper is having a bad day? Will it, like many humans, become uncooperative? Will it ask for some time alone? What happens if it knows that its purpose in life is just to take part in small talk? Thankfully, Pepper is only about four feet tall, with roller balls instead of legs, so if it is angry with and even turns on its owners, you'll be safe if you can make it upstairs.

    Aldebaran says in reality, they're probably quite a few years away from artificial intelligence that could create real emotions. Aldebaran wasn't immediately able to tell when Pepper will be available out of Japan, but additional sales are scheduled for July after the first 1, 000 units sell out. SoftBank currently uses the robots in its stores as greeters, and it plans to offer Pepper to other stores in the future. Hopefully "boredom" is not an emotion Pepper can feel.