If a diver surfaces too quickly, he may suffer the bends. Nitrogen (氮) dissolved (溶解) in his blood is suddenly liberated by the reduction of pressure. The consequence, if the bubbles (气泡) accumulate in a joint, is sharp pain and a bent body—thus the name. If the bubbles form in his lungs or his brain, the consequence can be death.

    Other air-breathing animals also suffer this decompression (减压) sickness if they surface too fast: whales, for example. And so, long ago, did ichthyosaurs. That these ancient sea animals got the bends can be seen from their bones. If bubbles of nitrogen form inside the bone they can cut off its blood supply. This kills the cells in the bone, and consequently weakens it, sometimes to the point of collapse. Fossil (化石) bones that have caved in on themselves are thus a sign that the animal once had the bends.

    Bruce Rothschild of the University of Kansas knew all this when he began a study of ichthyosaur bones to find out how widespread the problem was in the past. What he particularly wanted to investigate was how ichthyosaurs adapted to the problem of decompression over the 150 million years. To this end, he and his colleagues traveled the world's natural-history museums, looking at hundreds of ichthyosaurs from the Triassic period and from the later Jurassic and Cretaceous periods.

    When he started, he assumed that signs of the bends would be rarer in younger fossils, reflecting their gradual evolution of measures to deal with decompression. Instead, he was astonished to discover the opposite. More than 15% of Jurassic and Cretaceous ichthyosaurs had suffered the bends before they died, but not a single Triassic specimen (标本) showed evidence of that sort of injury.

    If ichthyosaurs did evolve an anti-decompression means, they clearly did so quickly—and, most strangely, they lost it afterwards. But that is not what Dr Rothschild thinks happened. He suspects it was evolution in other animals that caused the change.

    Whales that suffer the bends often do so because they have surfaced to escape a predator (捕食动物) such as a large shark. One of the features of Jurassic oceans was an abundance of large sharks and crocodiles, both of which were fond of ichthyosaur lunches. Triassic oceans, by contrast, were mercifully shark- and crocodile-free. In the Triassic, then, ichthyosaurs were top of the food chain. In the Jurassic and Cretaceous, they were prey (猎物) as well as predator—and often had to make a speedy exit as a result.

    WELCOME TO THE VIRTUAL REALITY CINEMA AMSTERDAM

    World's First Virtual Reality Cinema

    Going to the VR CINEMA offers you the opportunity to watch movies like you've never done before. You can see 360 degree movies using a VR headset. In the VR CINEMA, ringing mobile phones and noisy visitors belong to the past. Furthermore, traditional red cinema chairs or the big white screen are nowhere to be found. Instead, a Samsung Galaxy S6 (smart phone) together with the Samsung Gear VR (virtual reality glasses) transports you to a completely new world. Headphones shut out background noise, and above all, offer super sound quality. Turning chairs allow you to freely look around and see what's happening above, below, behind, in front, on the right and on the left side of you. So no sore neck, we promise.

    In the VR CINEMA, you will experience 30 minutes of the coolest virtual reality films. We proudly present four film selections in different themes in order to please every virtual reality lover. Are you brave enough for our scary films? Will you immerse (沉浸于) yourself in VR documentaries from around the globe? Do you prefer to go on an adventurous journey like no other? Or do your kids want to swim with dolphins, interact with magical characters, and experience the moving stories beyond imagination? Supernatural, Documentary, Journey and Fun are waiting for you!

    For kids, young and older ones, there's the cheerful and colourful selection. The only thing you have to do is sit back, relax and enjoy the VR experience of your choice.

    Location: Oosterdokskade 5, 1011 AD Amsterdam The Netherlands

    Tel: +31(0) 6 27 00 69 16

    E-mail: mail@thevrcinema.com

    Ticket Price: ￡12.5

    Opening hours: Wednesday, Thursday & Friday: 14:00-21:00

    Saturday & Sunday: 12:00-22:00

    On November 14, 1902, President Theodore Roosevelt was on a hunting trip in Mississippi while trying to settle a line(边界) problem between Mississippi and Louisiana. Being an expert outdoorsman, he liked to hunt large animals.

    However, his hunt was going poorly that days, and he couldn't seem to find anything worthy of firing his gun. His followers, trying to help him, caught a Louisiana black baby bear for the President to shoot, but he refused. The thought of shooting a bear that was tied to a tree did not seem sporting, so he spared the life of the baby bear and set it free.

    A famous political cartoonist for the Washington Star, Mr. Clifford Berryman, drew a cartoon titled. Drawing the Line in Mississippi, which used the story of the President refusing to shoot the bear.

    The cartoon in the Washington Star showed Teddy Roosevelt, gun in hand, with his back turned on a pretty baby bear. Morris Michtom, owner of a Brooklyn toy store, got the idea from the cartoon and make a toy bear. Planning to use it only as a display, he placed the bear in his toy store window, and next to it placed a copy of the cartoon from the newspaper. To Michtom's surprise, he was surrounded by customers eager to buy it. He asked for and received President Roosevelt's permission to use his name for the bears that he and his wife made, and the Teddy Bear was born! Michtom soon made Teddy bears by the thousands. The money from selling Teddy bears made him, in 1903, form the Ideal Toy Company.

    Many people prefer eating out instead of cooking at home. A change appears to be taking place, though, and millennials are leading the way. According to one survey, more young people are starting to cook at home for three basic reasons: They can save money, eat healthy and waste less food.

    Popular TV chefs are also getting millennials excited about learning some basic cooking skills. Many millennials view cooking as a form of entertainment and self-expression. They proudly post pictures of their cooking creations on Facebook or Instagram, and invite friends over to share the cooking experience.

    Many millennials have also found ways to avoid wasting food. After roasting a chicken, they put the leftover bones in their freezer instead of the garbage can. Later, they use the bones to make chicken stock which is an important ingredient in many dishes.

    They also hate throwing out fruit that's too old. To avoid that situation, they bake ripe fruit like berries and bananas for 15 minutes at 175 degrees C. Then they freeze it overnight. After that, they place the fruit in plastic bags and store it their freezer for later use.

    Now any millennials only eat at restaurants that have excellent food-waste policies. These servants use every part of the vegetables they buy, including their stems and roots, in dishes. They also use beef, chicken and pork bones to make their own stock.

    Millennials also reduce food waste by only buying what they require. Before going to a market, they write down what they need and don't buy anything else. They say they won't purchase more food than they can consume.

    A Latin phrase beloved by every old-fashioned British schoolmaster was mens sana in corpora sano—a healthy mind in a healthy body. Greater physical activity is associated with better mental, as well as physical health. And it might also be linked to greater worker productivity, and thus faster economic growth. That is the conclusion of a new report from a European think tank — RAND.

    The RAND study looks at different measures: absenteeism (when workers take time off for illness) and presenteeism (when they turn up for work but are less productive because of sickness). The latter measure was self-reported by employees, who were asked whether their work was negatively affected by health issues. The survey suggests that between 3 and 4.5 working days each year are lost as a consequence of workers being physically inactive. This is between 1.3% and 2% of annual working time. Most of this was down to presenteeism.

    Another potential gain from improved fitness is reduced health-care costs. In America, where health care is often provided through employment-based systems, firms could benefit. RAND estimates that total American health savings could be $6bn a year by 2025. But the study's authors conclude that if people met certain exercise targets, global GDP could be around 0.17-0.24% higher by 2050. Nothing to laugh at in a world of slowing growth.

    How to encourage workers to become more active? Rewards are useful but only if they have conditions; giving all employees free gym membership does not seem to work. Another RAND Europe study examined an experiment in which workers were each given an Apple watch, payable in instalments (分期付款) at a discounted price—but only to those who agreed to have their physical activity monitored. Monthly repayments depended on how much exercise they took.

    The problem is that many people are too optimistic about their health, ignoring the risks they face. This means that participation in workplace exercise plans tends to be low, around 7% in the sample studied by RAND. Firms are not the only ones that can encourage a healthier lifestyle; friends and families are likely to be more important. But businesses can play a bigger role.

    If RAND is right, this may bring them financial benefits. Company taskmasters may yet grow fond of an adapted saying: mens sana in corporate sano.

Don't ignore (忽略) the difference teenagers can make.

John Michael Thomas, 14, Florida

When John Michael Thomas decided to honor his friend and classmate Elizabeth Buckley, who died from cancer, he remembered how much she loved peacocks (孔雀).

He wanted to build a life-sized peacock fountain (喷泉) in Elizabeth's favorite park in the city. He thought it could be a place for people to relax and be inspired.

John Michael raised $52,000 to build the fountain.

Barrett England, 13, Utah

The wheels began to turn for Barrett England when he heard about Karma Bike shop, a place where young people can earn free bikes by reading and performing community (社区) service.

Barrett visited Karma's owner with his idea: He would collect and repair used bikes and donate them to the shop.

He expected to get about 10 donated bikes. In the end, Barrett received 39.

Zachary Blohm, 15, Wisconsin

The 25-year-old playground at an elementary school near Milwaukee, Wis. was so small that only 70 of its 575 students could play on it at a time.

That's when Zachary Blohm saved the day. He and some volunteers wanted to build a huge playground. To raise money, Zac planned T-shirt and bake sales, sold tickets and more. He held monthly money-raising events for more than a year. Overall, he collected $130,000 — enough to finish his project.

Jack Zimmerman, 16, New Jersey

For some people, finding a meal is as simple as opening the refrigerator. For more than 366,000 hungry kids in New Jersey, it's not that easy.

That fact didn't sit well with Jack Zimmerman, who organized a drive to lessen childhood hunger in his state. His goal: create 40,000 packaged meals that could be donated to those in need.

On game day, Jack and his volunteers started their work. After the final count, the team had packaged 47, 124 meals—well above Jack's goal.