When people reunite with their loved ones, it's usually all extremely happy moment. But what is their most common response to seeing them again? It may seem strange，but most of the time they break down in tears.

    Now a group of psychologists from Yale University say they have found the reason why, and that crying tears of joy may well be the body's way of keeping emotional balance. “They seem to take place when people are overtaken by strong positive emotions, and people who do this seem to recover better from those strong emotions,” Oriana Aragon, the lead researcher said.

    Aragon and her fellow psychologists looked at hundreds of participants' emotional responses to different things, including happy reunions and cute babies. Many participants said they would react in a negative or aggressive way to the positive things —— to cry at happy moments and want to pinch(捏)a cute baby's face or even tell them “I want to eat you up!” But then researchers found that these people were able to calm down from strong emotions more quickly.

    There are many other examples of times when people respond to a positive experience with a negative emotional reaction. At an exciting concert, fans scream at their idols(偶像). People who have just had a big lottery win are often in floods of tears. “These findings advance our understanding of how people express and control their emotions, which is importantly related to mental and physical health, the quality of relationships with others, and even how well people work together.” said Aragon．

    In order to help customers find what they want quickly, it's important to keep the thousands of titles in the Main Street Movies store organized properly. This section of the Employee Handbook will tell you how to organize videos.

    Each Main street Movies store has three main sections:

1). New Releases Wall.

2). Film library.

3). Video Games.

    New Releases Wall. Almost 70 percent of movie rentals are new releases, and that is the first place where most customers go when they enter the store. The center section of shelves on this wall holds Hottest Hits. When new titles come into the store, place them on this wall in alphabetical order. The shelves beside Hottest Hits are called Recent Releases. The New Releases Wall, including the Hottest Hits and Recent Releases shelves, holds about 350 titles.

    Film Library. The thousands of titles in the Film Library are organized into categories. The films within each category are displayed alphabetically. Here are the categories and their two-letter computer codes:

    Foreign Language titles include films that were originally made in a foreign language and films with foreign language subtitles. A sticker on the back of each box tells which type of film it is.

    Video Game. All the video games in Main street Movies are arranged in alphabetical order. Although video games represent only a small percentage of our inventory(库存), they are stolen more often than any other type of goods in our store. Therefore, video games are never displayed on the shelves. Shelves in the Video Game section hold cardboard with pictures and information about each game. When a customer wants to rent a particular game, you then find the game from the locked case behind the counter.

    My father was attached to gardening by birth. One of my earliest memories is following Dad barefoot around in the garden with both hands blackened from digging in the soil. The garden was a wonderland full of possibilities.

    As Dad grew older, he still loved gardening. Even when he was diagnosed with cancer, he still planted all sorts of plants. Sometimes, I would come over to visit, and we would walk together in the garden. But then, something changed. Like the weeds that took over his garden, the cancer grew rapidly in Dad, and the doctor gave up. I stayed with Dad twenty-four hours a day and I found myself in all kinds of uncomfortable situations with Dad until I promised to care for the garden.

    Though I had heard the words of the doctor, what really made me believe that Dad was dying was the state of his garden. That year, he only planted tomatoes. Too tired to weed them, he simply tied them with strong strings to the fence and let them be. It made me sad to see them ignored, so I would come over and water them once in a while, and remove the weeds. I still remember the day I picked the last tomato from the vine(藤). That day was one of the saddest I had ever experienced in my life.

    Three years ago, I decided to plant my own garden. I decided I would start out with just a few tomatoes. That morning when I moved to the garden, something caught the corner of my eye and I had to smile. It was my eight-year-old son Nathan, standing barefoot in the soil, happily playing in soil.

    Scientists recently discovered that pictures on cave walls at Creswell Crags are the oldest known in Great Britain. But they didn't find out in the usual way.

    Archaeologists often date cave art with a process called radiocarbon dating. The technique can measure the age of carbon found in charcoal (木炭) drawings or painted pictures. Carbon is an element found in many things, including charcoal and even people. But in this case, there was no paint or charcoal to test. People carved the pictures of animals and figures into the rock using stone tools. The scientists had an "aha!" moment when they noticed small rocks stuck to the top of the drawings. The small rocks must have formed after the drawings were made.

    "It is rare to be able to scientifically date rock art," said Alistair Pike, an archaeological scientist at Britain's University of Bristol. "We were very fortunate that some of the engravings were covered by stalagmites(石笋).

    When a test proved that the stalagmites formed 12,800 years ago, the scientists knew the art underneath them had to be at least that old. And some of the animals shown, like the European bison, are now extinct-another tip-off that the art is quite old.

    The artists came to Creswell Crags, This place is one of the farthest points north reached by our ancient ancestors during the Ice Age. At that time, much of the North Sea was dry, so people could move about more easily.

    Some tools and bones found there are 13,000 to 15,000 years old. They show that the travelers hunted horses, reindeer, and arctic hare. Their artwork is similar to art in France and Germany. It tells scientists that the Creswell Crags artists must have had a close connection to peoples several thousand kilometers away—another important clue to understanding how humans spread out across the world.

An Edinburgh inventor has created a fully biodegradable bottle that is made from paper and a secret combination of plant materials, and it could help save the planet's oceans from plastic pollution and can also be eaten by sea creatures.

The Edinburgh-based Durham University chemistry graduate James Longcroft started a non-profit bottled water company two years ago. He wanted to put all his profits into a charity that provided clean drinking water to countries in Africa.

However, after concerns about the environmental impact of plastic bottles, Mr. Longcroft decided the Edinburgh and London-based company, Choose Water, should go plastic-free. So he came up with a new type of water bottle—a waterproof paper bottle.

"The outside is made from recycled paper, but the inside has to be waterproof, and provides strength so the bottle would keep its structure, and keep the water fresh," Mr. Longcroft said.

When the bottle is thrown in the ocean the degrading process begins within hours leaving the bottle totally degraded (分解)within weeks. The steel cap breaks down within a year.

Mr. Longcroft now believes these novel bottles could revolutionise the industry and says the cost of producing the bottle is around 5 pence more than one made from single-use plastic.

"The main difficulty we face is breaking into a saturated (饱和的)market and competing with an old industry," he said. "Changing an industry will be a big uphill battle, but with the support from the public, we will change the way we look at bottled water."

Researchers warn that eight million tonnes of plastics currently find their way into the ocean every year which will stay in the environment for centuries.

"We really want to get our bottles on shelves and into people's hands as soon as possible—if we can stop even one plastic bottle ending up in the environment it will be worth it," said Mr Longcroft.