How the Grand Canyon (大峡谷) was created remains one of the geology's greatest mysteries. Some evidence suggests that the process was a gradual one in which the Colorado River (which runs through the canyon) slowly cut deeper and deeper into the ground over millions of years. But volcanic rock samples taken from the canyon now suggest that the canyon was down-cut instead.

    Down-cutting is when a flood of water rushes over a landscape (地形) with enough force to cut deeply into the ground and leaves behind a canyon. Such a flood is usually released when a natural or man-made dam (堤坝) bursts.

    Robert Webb, a research geologist, says natural dams seem to have formed and broken across the Colorado River several times during the last million years. The dams were built when lava(熔岩) from the eruptions of nearby volcanoes flowed into the river. The lava hardened into hard rocks and blocked the river, causing it to back up and form a lake. Each time the lake grew so huge that it broke the rock dam, releasing a flash flood that furthered the down-cutting process and deepened the canyon.

    Down-cutting is not just an earthly event. Satellite photos sent back from Mars suggest that the process has happened there, too, say many other researchers.

    The photos, taken by the Mars Global Surveyor, indicate that an enormous lake existed on Mars 3.5 billion years ago. The lake spilled into a large nearby hole. One edge of the hole broke, releasing a flash flood that quickly carved out a grand canyon.

    The existence of down-cutting on Mars is just one more piece of evidence that the cold, dry planet was once warm and wet.

    While the U.S. is still debating about getting rid of the penny, Sweden is rapidly moving towards abolishing (to end) currency altogether. Though this may sound radical (过激的), it is a natural evolution in this digital society.

    Sweden, which was the first European country to introduce banknotes in 1661, has just been working harder to convince its residents that digital payments are a safer alternative to carrying cash.

    Over the years, the idea has gained popularity with residents, especially the younger generation that is much more comfortable with technology. Today many banks don't even have ATMs and some have stopped handling cash altogether!

    Tickets to ride public buses in most Swedish cities can only be bought via cell phones. Numerous businesses are also moving towards accepting only digital payments. Even the homeless that sell street paper to make ends meet have to start accepting this mode of payment!

    But despite its growing popularity, some people don't like this radical idea. They include the homeless, elderly people as well as those living in rural areas who are still uncomfortable with mobile phones and computers. But the officials are confident that in the very near future, they will be able to convince everyone to move this safe and more cost-effective payment system.

    Sweden is not the only country trying to abolish paper currency and coins. The movement is rapidly gaining ground in Denmark and Finland as well. In 2014，Israel announced a three-step plan to go cashless and just last week the vendors (小贩) of a popular street in Sydney declared they would stop accepting currency from customers. Whether this phenomenon spreads remains to be seen. But one thing is for sure-With increasingly advanced payment systems being introduced every day, pulling out cash is rapidly becoming “uncool”.

    A psychologist walked around a room while teaching stress management to the audience. As she raised a glass of water, everyone expected they'd be asked the “half empty or half full” question. Instead, with a smile on her face, she inquired. “How heavy is this glass of water?”

    Different answers are called out from the audience.

    She replied, “The absolute weight doesn't matter. It depends on how long I hold it. If I hold it for a minute, it's not a problem. If I hold it for an hour, I'll have an ache in my arm. If I hold it for a day, my arm will feel numb and paralyzed. In each case, the weight of the glass doesn't change, but the longer I hold it, the heavier it becomes.”

    She continued. “The stresses and worries in life are like that glass of water. Think about them for a while and nothing happen. Think about them a bit longer and they begin to hurt you. And if you think about them all day long, you will feel paralyzed and be incapable（无能力的）of doing anything.”

    It's important to remember to let go of your stresses. As early in the evening as you can, put all your burdens down. Don't carry them through the evening and into the night.

    Remember to put the glass down!”

    Comments:

    Aye Chan Aung－February 27, 2017 at 11:37am

    Short but valuable! It clearly teaches me how to deal with stresses.

    Nelson Malicdem－February 28, 2017 at 8:23 pm

    Wow! Thank the author and the one who submitted the article. I am experiencing a challenge when I read this. It gives me peace. What exactly is in the article is what I am doing. My burden actually paralyzes me without my knowing it. I put down the glass of water that I am holding. Thank you so much!

    Environmentalists said our planet was bound to die. Now one man says they are wrong. “Everyone knows the planet is in bad shape,” thundered a magazine article last year. “Species are being driven to die out at record rates, and the rivers are so poisonous that fish are floating on the surface, dead.”

    But there's growing belief that what everyone takes for granted is wrong: Things are actually getting better. A new book is about to overturn our most basic assumptions about the world's environment. Rivers, seas, rain and the atmosphere are all getting better.

    The total amount of forests in the world is not declining. The Skeptical Environmentalist by Bjorn Lomborg, professor of statistics at the University of Aarhus in Denmark, is an attack on the misleading claims of environmental groups, and the “bad news” culture that makes people believe everything is getting worse.

    Now the attacks are increasingly coming from left-wing environmentalists such as Lomborg, a former member of Greenpeace. The accusation is that, although the environment is improving, green groups — with profits of hundreds of millions of pounds a year — are using scare tactics (战术) to gain donations. Lomborg's book doesn't deny global warming — probably the biggest environmental threat — but destroys almost every other environmental claim with many official statistics.

    The Worldwatch Institute claims that deforestation(采伐森林) has been speeding over the last 30 years. Buy Lomborg says that is simply rubbish. Since the dawn of agriculture the world has lost about 20% of its forest cover, but in recent decades the forest area's depleting has come to a stop. According to UN figures, the area of forests has remained almost steady, at about 30% of total land area, since 1940s. Forests in countries such as the US, UK and Canada have actually been expanding over the past 40 years. Despite all the warnings the Amazon rainforest has only shrunk by about 15%.

    Nor are all our species dying out. Some campaigners claim that 50% of all species will have died out within 50 years. But other studies show only 0.08% of species are dying out each year. Conservation efforts have been successful. Whales are no longer threatened and the bald eagle is off the endangered list.

    Environmental groups claim that many of the improvements are the results of their campaigns. Stephen Tindale, director of Greenpeace UK, said, “There are important examples, such as acid rain and ozone, where things weren't as bad as predicted, and that's because our behavior changed.”

Amsterdam Destination Guide

    Amsterdam is one of the most popular travel destinations in the world, famous for its beautiful canals, top art museums, cycling culture and so on. It is the capital and most populous city in the Netherlands and often referred to as the “Venice of the North” because of its expansive system of bridges and canals. Here are some of the key points to remember as you plan your trip to Amsterdam.

    Must-See Attractions

    Most visitors begin their Amsterdam adventure in the Old Centre, which is full of traditional architecture, shopping centers, and coffee shops. You'll also want to check out Amsterdam's Museum Quarter in the South District, which is great for shopping at the Albert Cuyp Market and having a picnic in the Vondel park. The top museums to visit there are the Rijks musuem, the Ann Frank House, and the Van Gogh Museum.

    If You Have Time

    There are several other unique districts in Amsterdam, and you should try to explore as many of them as time allows. The Canal Ring is a UNESCO World Heritage Site that was originally built to attract wealthy home owners and is a center for celebrity spotting and nightlife today. The Plantage area has most of the city's museums, including the Jewish Historical Museum, the Scheepvaart Museum, and the botanical gardens.

    Money Saving Tips

    Unless you really want to see the tulips (郁金香) blooming, avoid booking between mid-March and mid-May. This is when hotel and flight prices rise.

    Look for accommodations in Amsterdam's South District, where rates are generally cheaper than in the city center.

    Buy train tickets at the machine instead of the counter to save a bit of money.

    Instead of hiring a tour guide, hop on a canal boat. They're inexpensive and will give you a special point of view of the city.

    Check out our homepage to view price comparisons for flights, hotels, and rental cars before you book.

    The largest genetic study of mosquitoes has found their ability to resist insecticides(杀虫剂) is evolving rapidly and spreading across Africa, putting millions of people at higher risk of contracting malaria(疟疾).

British scientists who led the work said mosquitoes' growing resistance to control tools such as insecticide-treated bed nets and insecticide spraying, which have helped cut malaria cases since 2000, now threatens "to disturb malaria control" in Africa.

    "Our study highlights the severe challenges facing public efforts to control mosquitoes and to manage and limit insecticide resistance," said Martin Donnelly of the Liverpool School of Tropical Medicine, who worked on the study with a team from Britain's Wellcome Trust Sanger Institute.

    Latest World Health Organization (WHO) data show that 216 million people were infected last year with the malaria parasite(寄生虫), which is transmitted by blood-sucking Anopheles mosquitoes. The disease killed 445,000 people in 2016, and the majority of them were children in sub-Saharan Africa.

    To understand how mosquitoes are evolving, the researchers sequenced the DNA of 765 wild Anopheles mosquitoes taken from 15 locations across eight African countries. Their work, published in the journal Nature on Wednesday, created the largest data resource on natural genetic variation for any species of insect.

    Analyzing the data, the scientists found that the Anopheles gamblae mosquitoes(冈比亚疟蚊)were extremely genetically diverse compared with most other animal species. This high genetic diversity enables rapid evolution, they said, and helps to explain how mosquitoes develop insecticide resistance so quickly.

    The data also showed the rapid evolution of insecticide resistance appeared to be due to many previously unknown genetic variants(变体)within certain genes. The scientists said these genetic variants for insecticide resistance were not only emerging independently in different parts of Africa, but were also being spread across the continent by mosquito migration.

    Michael Chew, an expert at Britain's Wellcome Trust global health charity which helped fund the research, said the finds underlined the importance of pushing scientific research ahead to control malaria.

Global efforts to control malaria through effective vaccine, insecticides and the best drug combinations require urgent, united action by scientists, drug companies, governments and the WHO.