Traffic problems are an everyday concern in many cities, including Washington, D. C. A growing number of Washingtonians are turning to bicycles to get to and from work. In fact, the number of commuters who use bicycles has doubled in the city since 2007.

    Ralph Buehler teaches urban planning at the Virginia Polytechnic Institute and State University，popularly known as Virginia Tech. He has written a book about urban biking, called City Cycling. He says there is a reason why urban bike tiding is now becoming more popular.

    “Over the last 60 to 70 years, cities in America have been adapted to the automobile.”

    “Most cities took advantage of the money coming for the interstate (洲际)highway system, from the federal government, starting in 1956. There was a 90 percent federal match(补贴)so the cities only had to put up 10%. It was very tempting.(临时的).”

    In the years after World War Two, many Americans moved to suburban communities, just outside major cities, They decided to travel great distances to and from work in exchange for a home in the suburbs. Their cars became a symbol of freedom.

    But today, many people believe they can save money by living in the city.

    Greg Billing is with the Washington Area Bicyclist Association. “When a person makes a change from using a car to using a bike, he/she is saving anywhere between 8 or$9,000 a year.”

    Ralph Buehler says governments save money when people use bicycles. “Building bicycling facilities(设施) is much cheaper than building and maintaining road facilities or public transport.”

    Washington, D.C has also taken steps to protect bike riders. It approved a safe passing law and created areas on the road between cars and bikes.

    The United States Census Bureau says 4% of the city's workers ride to work by bike. The only city on the East Coast with more bike commuters is New York.

    Eating too much fatty food, exercising too little and smoking can raise your future risk of heart disease．But there is another factor that can cause your heart problems more immediately: the air you breathe.

    Previous studies have linked high exposure (暴露）to environmental pollution to an increased risk of heart problem, but two analyses(分析) now show that poor air quality can lead to heart attack or stroke (中风）within as little as a few hours after exposure．In one review of the research, scientists found that people exposed to high levels of pollutants (污染物）were up to 5% more likely（可能的） to suffer a heart attack within days of exposure than those with lower exposure．A separate study of stroke patients showed that even air that the U．S．Environmental Protection Agency (EPA) considers to be of “moderate” (良好）quality and relatively safe for our health can raise the risk of stroke as much as 34% within 12 to 14 hours of exposure.

    The authors of both studies stress（强调）that these risks are relatively（相对的）small for healthy people and certainly modest compared with other risk factors such as smoking and high blood pressure．However, it is important to be aware of these dangers because everyone is exposed to air pollution regardless of lifestyle choices．So stricter regulation（规章制度）by the EPA of pollutants may not only improve environmental air quality but could also become necessary to protect public health.

    There are two great trends on parents bringing up children today．First，children are now praised to an unbelievable degree．As Dorothy Parker once joked，American children aren't raised；they are motivated．Children are constantly told how special they are．The second is that children are honed(磨砺) to an unimaginable degree．Parents spend much more time than in past generations on their children's development．

    These two great trends—greater praise and greater honing—combine in close ways. Parents shower their kids with affection，but it is intermingled with the desire to help their children achieve success．Parents are happy when their child studies hard，practices hard，wins first place，gets into a famous college．

The wolf of conditional love is hidden in these homes．The parents feel they love their children in all circumstances．But the children often think differently．They feel that childhood is a performance—on the athletic field，in school and beyond．The shadowy presence of conditional love produces a fear，the fear that there is no completely safe love．

    Meanwhile，children who are uncertain of their parents' love develop a great hunger for it. This conditional love is1ike an acid that affects children's criteria to make their own decisions about their own colleges，majors and careers．At key decision-points，they unconsciously imagine how their parents will react．

    These children tell their parents those things that will bring praise and hide the parts of their lives that won't. Studies suggest that children who receive conditional love often do better in the short run．They can be model students．But they suffer in the long run. They come to hate their parents．They are so influenced by fear that they become afraid of risk．

    Parents today are less likely to demand obedience(顺从) with explicit rules and lectures．But they are more likely to use love as a tool to exercise control. But parental love is supposed to ignore achievement. It's meant to be an unconditional support -a gift that can not be bought and cannot be earned．

    A sunflower is a sunflower. A mobile phone is a mobile phone. But can you combine the two to do something for your local environment? As early as next year it may well be possible. When you have finished with your mobile phone you will be able to bury it in a garden or a plant pot and wait for it to flower.

    A biodegradable (生物所能分解的) mobile phone was, this month, introduced by scientists. It is hoped that the new type of phone will encourage consumers to recycle.

    Scientists have come up with a new material over the last five years. It looks like any other plastic and can be hard or soft, and is able to change shape. Over time it can also break down into the soil without giving out any poisonous chemicals. British researchers used the new material to develop a phone cover that contains a sunflower seed. When this new type of cover turns into waste, it forms fertilizers. These feed the seed and help the flower grow.

    Engineers have designed a small transparent (透明的) window to hold the seed. They have made sure it only grows when the phone is throw n away. “We've only put sunflower seeds into the covers so far. But we are working with plant experts to find out which flowers would perform best. Maybe we could put roses in next time.” said one scientist.

    As phone technology is developing so quickly, people are constantly throwing their mobiles away. This means manufacturers are under pressure to find ways of recycling them. Some 650 million mobile phones have been sold this year. Most of them will be throw n away within two years, adding plastic, heavy metal and chemical waste to the environment. A biodegradable cover can offer some relief for nature, according to the scientists.

    “The seed comes out and the flower grows in the pot so you don't have to concern yourself with the phone when you have finished using it,” said Kerry Kirwan. She leads the research team, which is based at the University of Warwick in Britain.

    Imagine putting a seed in a freezer, waiting 30,000 years, and then taking the seed out and planting it. Do you think a flower would grow?

    Amazingly, scientists have just managed to do something very similar. They found the fruit of an ancient plant that had been frozen underground in Siberia—a region covering central and eastern Russia—for about 31,800 years. Using pieces of the fruit, the scientists grew plants in a lab. The new blooms have delicate white petals. They are also the oldest flowering plants that researchers have ever revived from a deep freeze.

    “This is like regenerating a dinosaur from tissues of an ancient egg,'' said Jane Shen-Miller, a biologist of University of California, Los Angeles.

    The plant has a long history. Back when mammoths and woolly rhinoceroses walked on the land, an Arctic ground squirrel buried seeds and fruits in an underground chamber near the Kolyma River in northeastern Siberia. The ground became pennafrost, a layer of soil that stays frozen for a long time.

    Recently, Russian scientists dug out the old squirrel hole and found the plant remains 38 meters below the surface. Back at the lab, the team fed nutrients to tissue from three of the fruits to grow shoots. Then the scientists transferred the shoots to pots filled with soil. The plants produced seeds that could be used to grow even more of them.

    It's important for scientists to know that plant tissues can still be revived after being frozen for a long time. That's because many researchers are trying to preserve the seeds of modem plants by freezing them and then storing them in giant lockers at various spots around the globe. One such endeavor, an underground facility in Norway, is called the Svalbard Global Seed Vault. It stores hundreds of thousands of frozen seeds. If a plant ever goes extinct, scientists could bring it back by taking its seeds from the Svalbard or other storage lockers.

    "No one knows how long they are able to live for, but freezing is basically the format for many plant conservation attempts nowadays," Jane Shen-Miller said. It's a good thing that at least some plants are tough enough to survive in the experience.

    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.