Exercise may help to safeguard the mind against depression through previously unknown effects on working muscles, according to a new study involving mice.

    Mental health experts have long been aware that even mild, repeated stress can contribute to the development of depression and other mood disorders in animals and people. Scientists have also known that exercise seems to cushion against depression. But precisely how exercise, a physical activity can lessen someone's risk for depression, a mood state, has been mysterious. So for the new study, researchers at the Karolinska Institute in Stockholm studied the brains and behavior of mice in a complicated and novel fashion.

    We can't ask mice if they are feeling cheerful or in low spirits. Instead, researchers have pictured certain behaviors that indicate depression in mice. If animals lose weight, stop seeking out a sugar solution when it's available — because, probably, they no longer experience normal pleasures — or give up trying to escape from the cold-water zone just freeze in place, they are categorized as depressed. And in the new experiment, after five weeks of frequent but low-level stress, such as being lightly shocked, mice displayed exactly those behaviors. They became depressed.

    The scientists could then have tested whether exercise blunts (延缓) the risk of developing depression after stress by having mice run first. But, frankly, from earlier research, they wanted to know how, so they bred pre-exercised mice. A wealth of earlier research by these scientists and others had shown that aerobic exercise, in both mice and people, increases the production within muscles of an enzyme (酶) called PGC-1alpha. The Karolinska scientists suspected that this enzyme somehow creates conditions within the body that protect the brain against depression. Then, the scientists exposed the animals, which without exercising, were in high levels of PGC-1alpha to five weeks of mild stress. The mice responded with slight symptoms of worry. But they did not develop depression. They continued to seek out sugar and fought to get out of the cold-water zone. Their high levels of PGC-1alpha appeared to make them depression-resistant. Finally, to ensure that these findings are relevant to people, the researchers had a group of adult volunteers complete three weeks of frequent endurance training, consisting of 40 to 50 minutes of moderate cycling or jogging. The scientists conducted muscle biopsies (活体检查) before and after the program and found that by the end of the three weeks, the volunteers' muscle cells contained substantially more PGC-1alpha than at the study's start. The finding of these results, in the simplest terms, is that “you reduce the risk of getting depression when you exercise,” said Maria Lindskog, a researcher at the Karolinska Institute.

    Schools across the world are trying to come up with solutions to keep students active. Some are replacing traditional classroom chairs with exercise balls or standing desks. At Ward Elementary School in Winston, North Carolina students have adopted a new program that requires riding fixed bikes while reading.

    'Read and Ride' is the creation of school counselor Scott Ertl, who came up with the idea while he was exercising and reading at the gym. Believing it would be a fun way to convince students to become more active, he placed one in the corner of his classroom and encouraged them to use it during independent reading classes.

    It was so popular that Ertl decided to add more bikes and offer the Read and Ride program to the entire school. Today Ward Elementary has a dedicated exercise room filled with bikes that can be used by students while completing their daily reading assignments.

    Besides making reading more fun, the program also helps students exercise at a comfortable pace without the pressure that comes with regular sports-related activities. It is also a perfect way to release energy during days when the weather is not helpful to outdoor activities.

    Most importantly, however, are the program's academic benefits. A year after Read and Ride was introduced at Ward Elementary School, students actively involved in the program demonstrated an astonishing 83% reading proficiency. Those that had not taken advantage of the exercise bikes tested at a much lower, 41%.

    Though the substantial improvement in academic achievement cannot all be attributed to programs like Read and Ride, experts believe they are a significant contributor. That's because studies have shown that physical activity stimulates（刺激） brain cells and helps prepare it for learning. As word of the difference made by this easy to execute exercise program spreads, don't be surprised to find schools across the country adopt “Read and Ride” for their students.

D

Preparing Cities for Robot Cars

    The possibility of self-driving robot cars has often seemed like a futurist's dream, years away from materializing in the real world. Well, the future is apparently now. The California Department of Motor Vehicles began giving permits in April for companies to test truly self-driving cars on public roads. The state also cleared the way for companies to sell or rent out self-driving cars, and for companies to operate driverless taxi services. California, it should be noted, isn't leading the way here. Companies have been testing their vehicles in cities across the country. It's hard to predict when driverless cars will be everywhere on our roads. But however long it takes, the technology has the potential to change our transportation systems and our cities, for better or for worse, depending on how the transformation is regulated.

    While much of the debate so far has been focused on the safety of driverless cars(and rightfully so), policymakers also should be talking about how self-driving vehicles can help reduce traffic jams, cut emissions(排放) and offer more convenient, affordable mobility options. The arrival of driverless vehicles is a chance to make sure that those vehicles are environmentally friendly and more shared.

    Do we want to copy — or even worsen — the traffic of today with driverless cars? Imagine a future where most adults own individual self-driving vehicles. They tolerate long, slow journeys to and from work on packed highways because they can work, entertain themselves or sleep on the ride, which encourages urban spread. They take their driverless car to an appointment and set the empty vehicle to circle the building to avoid paying for parking. Instead of walking a few blocks to pick up a child or the dry cleaning, they send the self-driving minibus. The convenience even leads fewer people to take public transport — an unwelcome side effect researchers have already found in ride-hailing(叫车) services.

    A study from the University of California at Davis suggested that replacing petrol-powered private cars worldwide with electric, self-driving and shared systems could reduce carbon emissions from transportation 80% and cut the cost of transportation infrastructure(基础设施) and operations 40% by 2050. Fewer emissions and cheaper travel sound pretty appealing. The first commercially available driverless cars will almost certainly be fielded by ride-hailing services, considering the cost of self-driving technology as well as liability and maintenance issues(责任与维护问题). But driverless car ownership could increase as the prices drop and more people become comfortable with the technology.

    Policymakers should start thinking now about how to make sure the appearance of driverless vehicles doesn't extend the worst aspects of the car-controlled transportation system we have today. The coming technological advancement presents a chance for cities and states to develop transportation systems designed to move more people, and more affordably. The car of the future is coming. We just have to plan for it.

    If you are travelling in Britain, besides so many world-class things to see and do in London, planning a day trip away from it can also be worthwhile.

    Stonehenge

    Stonehenge consists of a group of huge standing stones. The 5,000-year-old stones are one of the world's biggest mysteries that no one has figured out yet. While exploring Stonehenge, you can imagine wildly and decide for yourself how the stones came to be there and why. Although you can't touch the stones, you can walk among them and feel the changes of seasons.

    Windsor

    Most people visit Windsor to see Windsor Castle, where the Queen spends most of her time. The castle itself could keep you busy for days. The best way to appreciate Windsor Castle is to approach via the Long Walk, a straight road where there are no cars, but you might see some deer.

    Oxford

    Oxford is best known for its world-famous university. The large student population keeps the atmosphere young and fresh, though there's no shortage of history if you want it. 30 colleges make up the university itself. A tour of the colleges is a must—Harry Potter fans will recognize various locations used in the movies.

    Bath

    Founded by the Romans, who used the area's springs to create a spa retreat（水疗中心）, Bath's now the best tourist attraction of Southwest England. Visitors never miss the Roman Bath Complex, which is divided into four main parts—the Bath House, the Sacred Spring, the Roman Temple and the museum, which displays fascinating finds from the historical ruins of the city.

    If you have the opportunity to visit some places in New Zealand, then the list below is our recommendation.

    Fiordland National Park

    This park is part of the South Westland World Heritage Area and is New Zealand's largest national park and one of the largest in the world. The scenery in Fiordland is nothing short of extremely beautiful, with steep mountains, wild waterfalls, and abundant rain forests. Being able to come back and forth in its deep bay attracts most of the visitors.

    The area has some of the world's greatest walks including the world famous Milford Track, which was described as the finest walk in the world in the early twentieth century.

    Abel Tasman National Park

    Abel Tasman may be New Zealand's smallest national park, but the attractions are huge. Located in one of New Zealand's sunniest spots, the area also has the best beaches in the country.

    The popular Abel Tasman Walk is a great way to see this park. It takes 3-5 days to complete. Sea taxis are also available and can drop you off at any number of beaches within the park.

    Rotorua

    Accessible from New Zealand's biggest city, Auckland, Rotorua is famous for its volcanic activities. Rotorua is also famous for its plentiful lakes which are great for swimming and fishing. The surrounding area contains plenty of native bushes and some famous walks.

    Rotorua is also the best area in the country to experience and learn about Maori culture.

    Mt Cook National Park

    Mt Cook as well as the surrounding area is an alpine(高山的) park within the World Heritage listed in South Westland. The biggest peaks in all of Australasia are here. The park doesn't contain many trees or plants due to the altitude. Walks range from a two­hour walk to difficult tracks suitable for experienced mountaineers only.

    A helicopter or plane ride gives visitors excellent views of the mountains with the option of landing at the top of Tasman Glacier, a true permanent snow­covered alpine environment.

The World's Largest Insect

    This giant insect can be used as a toy.

    A child ties one end of a string to a stick and the other end around the "neck" of an insect. Holding the stick, the child lets the insect go. With a loud whirring sound, the insect takes off, pulling the string in a large curve over the child's head. The child laughs as the stick jumps around.

    The child is African, and the toy is the African Goliath beetle, the largest insect in the world.

    The Goliath is a true insect because it has six legs and a body that is divided into three parts. Like all beetles, it has two pairs of wings. The front pair are thick and stiff and protect the back pair, which are soft. It is these soft back wings that make the beetle fly forward. They also cause the loud whirring sound the beetle makes when it flies. To steer, the beetle twists and turns its legs the same way you steer a bike by turning its front wheel.

    African children often use the Goliath beetle as a toy. Although it is over 15 centimeters long, it is quite harmless.