A new study finds almost one third of the world's population is overweight. Since 1980, obesity rates(肥胖率)in children and adults have doubled in 73 countries, making people more worried. And rates are increasing in many other countries. Obesity is increasing faster in children than adults in many nations, including Algeria, Turkey and Jordan, the report said. But the world's weight problem is growing in both rich and poor countries alike. Researchers say an increasing number of people are dying of related health problems in what they called a "disturbing global public health problem."

    Researchers studied health information from 1980 through 2015. They examined obesity rates, average weight gain in 195 countries. They found that obesity rates are three times greater among youth and young adults in countries like China, Brazil and India. Almost 108 million children and more than 600 million adults were found to be overweight. Egypt had the highest number of overweight adults in 2015. Vietnam had the least. In the same year, the United States had the highest number of overweight children, and Bangladesh had the least.

    Yet hunger remains a problem in many areas. The United Nations said that almost 800 million people, including 300 million children, go to bed hungry each night. Experts said poor diets and lack of physical activity are mainly to blame for the rising numbers of overweight people.

    Growing populations have led to rising obesity rates in poor countries. Often, poor people will eat processed(加工的) foods instead of choosing a diet rich in vegetables.

    The London-based Overseas Development Institute studied the price of food in five countries: Britain, Brazil, China, Mexico and South Korea. It found that the cost of processed foods like ice cream and hamburgers has fallen since 1990. But the cost of fresh fruits and vegetables has gone up.

    Opened in 1847, the London Zoo is the world's oldest scientific zoo. Today it houses over 760 different species of animal and is the only zoo in London where you can experience big animals.

    Explore the “Into Africa” exhibit (展览) where you can come face to face with some of Africa's most unusual animals including hunting dogs, or try “Meet The Monkeys” an exciting walk-through experience. Other top exhibits include the Butterfly Paradise, where you can enjoy many species of butterfly as they fly around you.

    Make sure you don't miss feeding time at the Penguin Beach and find out more about these popular creatures from the zoo's experienced keepers. Penguin Beach, with a very large pool and underwater viewing areas, allows visitors to be close to the penguins like never before.

    Built in 2013, Tiger Territory is a great experience taking visitors deep into the world of these wonderful creatures.

    Rainforest Life is London's only living rainforest, where visitors can meet a variety of beautiful rainforest species including. In the all-new “Night Life” area you will discover the bats, and rats.

    With over 12,000 animals to see and incredible animal displays taking place throughout the day (including feeds and keeper talks), no visitor leaves disappointed. Learn more about London Zoo in our Interview with a Zoo Keeper on our London Pass Blog.

    You can visit the London Zoo for free with a London Pass—a fantastic saving of £23 for adults and over £16 for children. Children aged 3-4 will be charged on entrance fee for London Zoo.

    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.

    Amsterdam is a special city. There are many places you should not miss during your visit. Here is our list of the best.

    Amsterdam canal ring

    The city old centre is formed from canal rings, which give you the feeling of space, freedom and peace. Walk through these canal streets or better—take a trip by renting a boat yourself. Another way to explore the Venice of the North is to take a ride on a bicycle. Any way you decide for - enjoy this city.

    The National Maritime Museum

    The Maritime Museum is an attractive place to visit, especially with children. With many attractions in it, this colourful and enjoyable museum will help you understand the history of the Netherlands—a small nation which was one of the world's greatest sea powers.

Amsterdam Brown Cafe

    When you enter Amsterdam old cafes called Brown, at first it will seem too much from the past and too crowded, but the atmosphere is unique. Relax and watch - most of people around will be locals. Feel like one of them—the real Amsterdammers.

    Civic Guards Gallery

    This gallery is filled with old paintings from the Dutch Golden Age. The exhibited canvas may be not always the masterpieces of art, but these group portraits of Amsterdam citizens and their wives are an exquisite (精致的) document of the Dutch civilization and culture centuries ago.

    To avoid waiting lines we advise you to buy your tickets in advance online through our Amsterdam attractions and museums tickets webpage.

    Batteries can power anything from small sensors to large systems. While scientists are finding ways to make them smaller but even more powerful, problems can arise when these batteries are much larger and heavier than the devices themselves. University of Missouri (MU) researchers are developing a nuclear energy source that is smaller, lighter and more efficient.

    "To provide enough power, we need certain methods with high energy density (密度)", said Jae Kwon, assistant professor of electrical and computer engineering at MU. ''The radioisotope (放射性同位素) battery can provide power density that is much higher than chemical batteries."

    Kwon and his research team have been working on building a small nuclear battery, presently the size and thickness of a penny, intended to power various micro systems (MNEMS). Although nuclear batteries can cause concerns, Kwon said they are safe.

    "People hear the word 'nuclear' and think of something very dangerous." he said. "However, nuclear power sources have already been safely powering a variety of devices, such as pace-makers, space satellites and underwater systems."

    His new idea is not only in the battery's size, but also in its semiconductor (半导体). Kwon's battery uses a liquid semi conduct or rather than a solid semiconductor.

    "The key part of using a radioactive battery is that when you harvest the energy, part of the radiation energy can damage the lattice structure (晶体结构) of the solid semiconductor." Kwon said, "By using a liquid semiconductor, we believe we can minimize that problem."

    Together with J. David Robertson, chemistry professor and associate director of the MU Research Reactor, Kwon is working to build and test the battery. In the future, they hope to increase the battery's power, shrink its size and try with various other materials. Kwon said that battery could be thinner than the thickness of human hair.

    I.M. Pei, the Chinese-American, who was regarded as one of the last great modernist architects, has died at the age of 102.

    Although he worked mostly in the United States, Pei will always be remembered for a European project: His redevelopment of the Louvre Museum in Paris in the 1980s. He gave us the glass and metal pyramid in the main courtyard, along with three smaller pyramids and a vast subterranean (地下的) addition to the museum entrance.

    Pei was the first foreign architect to work on the Louvre in its long history, and initially his designs were fiercely opposed. But in the end, the French—and everyone else—were won over. Winning the fifth Pritzker Architecture Prize in 1983, he was thought as giving the 20th century "some of its most beautiful inside spaces and outside forms … His talent and skill in the use of materials approach the level of poetry."

    After studying architecture at the Massachusetts Institute of Technology and Harvard, Pei set up his own architectural practice in New York in 1955.

    Designing the John F. Kennedy Presidential Library & Museum in 1964 established him as a name. His East Building of the National Gallery of Art in Washington in 1978 changed people's ideas of a museum. The site was an odd trapezoid (梯形) shape. Pei's solution was to cut it in two. The resulting building was dramatic, light and elegant—one of the first crowd-pleasing cathedrals of modern art.

    Though known as a modernist, and notable for his forms based on arrangements of simple geometric (几何的) shapes, he once urged Chinese architects to look more to their architectural tradition rather than designing in a western style.

    In person, I.M. Pei was good-humored, charming and unusually modest. His working process was evolutionary, but innovation (创新) was never an intended goal.

    "Stylistic originality is not my purpose," he said. "I want to find the originality in the time, the place and the problem."