Dujiangyan is the oldest man-made water system in the world, and a wonder in the development of Chinese science. Built over 2,200 years ago in what is now Sichuan Province in Southwest China, this amazing engineering achievement is still used today to irrigate over 6,000 square kilometres of farmland, take away floodwater and provide water for 50 cities in the province.

    In ancient times, the region in which Dujiangyan now stands suffered from regular floods caused by overflow from the Minjiang River. To help the victims of the flooding, Li Bing, the region governor, together with his son, decided to find a solution. They studied the problem and discovered that the river most often overflowed when winter snow at the top of the nearby Mount Yulei began to melt as the weather warmed.

    The simplest fix was to build a dam, but this would have ruined the Minjiang River. So instead Li designed a series of channels built at different levels along Mount Yulei that would take away the floodwater while leaving the river flowing naturally. Better still, the extra water could be directed to the dry Chengdu Plain, making it suitable for farming.

    Cutting the channels through the hard rock of Mount Yulei was a remarkable accomplishment as it was done long before the invention gunpowder and explosives. Li Bing found another solution. He used a combination of fire and water to heat and cool the rocks until they cracked and could be removed. After eight years of work, the 20-metre-wide canals had been carved through the mountain.

    Once the system was finished, no more floods occurred and the people were able to live peacefully and affluently. Today, Dujiangyan is admired by scientists from around the world because of one feature. Unlike modern dams where the water is blocked with a huge wall, Dujiangyan still lets water flow through the Minjiang River naturally, enabling ecosystems and fish populations to exist in harmony.

    The surface of Venus（金星）has never seemed very hospitable. Temperatures change around 470℃（900℉）, the result of a runway greenhouse effect，and the pressure of its atmosphere, thick with carbon dioxide and sulfuric acid, is some 90 times that of Earth's. Lead（铅）would flow like water on Venus, and water cannot have existed in liquid form for perhaps a billion years.

    Now NASA'S Magellan spacecraft seems to have found one more horror in the nasty landscape: active volcanoes. Last week the space agency released the first detailed map of Venus and the most dramatic images ever made of its surface. The picture offer the best evidence to date that a planet once assumed dead is actually a lively pot of geological change.

    The most amazing image is of Venus's second tallest mountain, Maat Mons, which rises 8km（5 miles）. Most of the planet's many peaks, including 9.5-km-（6-mile-） high Maxwell Montes, look bright in the radar pictures Magellan takes from its orbit above the permanent could cover. That means they are strong reflectors of radar waves. But Maat Mons is dark; like the Stealth bomber, it absorbs much of the radar falling on it.

    This interesting fact, say project scientists, is a strong hint that the mountains has recently been covered with lava. Rock that sits on the surface of mountaintops appears to weather quickly in the hot，chemically reactive atmosphere, creating a soil that is rich in iron sulfide（硫化铁）• It is this mineral, the scientists believe, that can easily be seen on radar. If Maat Mons doesn't have any, it has probably been resurfaced, perhaps within the past few years.

    Such resurfacing has undoubtedly taken place in Venus lowlands: earlier images of the planet showed vast areas that are remarkably free of craters（火山坑）.That would be easy to explain on a Planet like Earth, where cratering from meteor strikes is erased by steady erosion. But while there is some evidence of wind erosion on Venus, the best explanation for the lack of cratering is periodic lava flow. Magellan has found direct evidence of such flows, including domelike upwellings and hardened streamed of rock trailing down the sides of Venusian peaks. There are also signs of other geologic activities, including dramatic faulting and several distinct incidents of mountain building. But the evidence can't indicate whether they really occurred millions of years ago. The case for active Venusian volcanoes is not yet proved, but Magellan, which is now well into its second complete survey of the planet's surface, may eventually settle the issue.

    Are you a social media addict? Are you always checking your smart phone to see how many "likes" you've received for your latest post? Maybe you feel comforted by the sound that someone has sent you a message?

    Don't worry, you're not alone. We check our phones an average of 150 times a day, and around 30% of the total time spent online is devoted to social media. Some experts now fear this habit could be damaging our mental health.

    This is something particularly bothering young adults, according to a study from the University of Pittsburgh. It found the more they used social media, the more likely they were to be depressed. In tests, those people who checked social media frequently were 2.7 times more likely to be depressed compared to those who spent most of their time generally surfing the Internet, who had just 1.7 times the risk.

    Some of us certainly feel sad when we're ignored on social media sites, or when we see someone else having a better time than us. But depression is a more serious condition and clinical psychologist, Abigael San, recently told the BBC that ,"It's a real issue, and it's been getting significantly worse over the last 5﹣6 years. You can get so hooked that it takes you away from your real relationships. "However, Abigael does admit that social media is more likely to worsen pre﹣existing issues than directly cause them.

    Other research by the University of Glasgow found that teenagers are affected by the 24﹣hour demands of their social media accounts. It found that those with higher levels of emotional investment in social media, and who use it at night, were more likely to feel depressed and anxious.

    Despite these warning signs, why do some of us continue to keep clicking? Well, I suppose we all want to be liked and we don't want to miss out on a conversation that's taking place online. But we need to know when to switch off our virtual online world and connect with the real world instead.

    Columbus made four voyages to the west between 1492 and 1504 in his vain（徒劳的）search for a sea route to Asia. The mystery of why he failed to find it haunted（萦绕心头的,耿耿于怀的） him and filled him with sadness.

    Wherever he went to Cuba（古巴）,Puerto Rico（波多黎各）,Jamaica（牙买加）,South America, Panama（巴拿马）,down the coast of Central America—it was always the same story. Instead of golden palaces, there were grass huts and palm-leaf tents. Instead of silk-robed merchant princes, he found "Indians" who did not have so much as a shirt on their backs.

    When Columbus explored the West Indies in 1493,he heard tales of a fierce Indian tribe（凶狠的印第安部落） who literally devoured（吞食） its defeated enemies after a battle. These people were called by many names in the area, including Calina, Canima, Carib, and Caniba. Columbus recorded the name of the American natives as Canibales in Spanish, a word which came to refer, within a few years, to any eater of human flesh（食人部落,食人族）.In the similar fashion, the word Caribbean, a title for the sea as well as for the region, came into English.

    At times Columbus knew that this new land was not China, not Japan, not the Spice Islands. He seemed to accept it as a part of the earth that the geographers of Europe had never heard of before. It was another world—and he called it exactly that—but Columbus also insisted until he died that land he had reached was an unknown part of Asia.

Things to Do in Atlanta

    Need a run-down of the top things to do next month? Here is what's going on in Atlanta.

    In the Mood

    Date: November 22 through November 26，2018

    Time: 2:00pm～5:30pm

    Phone: 770-916-2800

    If you love the music of the 1940s，then here's what you need to do this Sunday. Go to a 1940s musical show at Cobb Energy Performing Arts Centre. The music of Glenn Miller has a distinctive sound. No need to ask me twice. Are you "In the Mood"?

    Party With the Penguins

    Date: November 20 through November 25, 2018

    Time:11:00 am～2:00 pm

    Phone: 404-581-4000

    Celebrate Penguin Awareness Day at Georgia Aquarium's annual Party With the Penguins. The party will feature fun activities, including the chance to see an African penguin up close and learn how to help protect this endangered species.

    Callanwolde Arts Festival

    Date: November 21 through November 22, 2018

    Time:10:30 am～5:30 pm

    Phone: 404-872-5338

    Located at Callanwolde Fine Arts Center, this event is a festival for artists, and by artists, letting them have a voice in the creation and operations of the festival. If you are of the artistic persuasion or enjoy a creative scene, don't miss out.

    Foolio's Hoodilly Storytime

    Date: November 21 through November 27, 2018

    Time:1:00 pm～4:30 pm

    Phone: 404-523-3141

    We make up a brand-new story every week. Come and enjoy a new story each time at Dad's Garage Theatre. Little ones will get to help provide key parts of the story and even add in their own jokes. Interactive and out-of-the-ordinary fun for kids and parents!

Humans' overconsumption(过度消费) of resources is a leading contributor to global climate change, says University of Arizona researcher Sabrina Helm. Therefore, it's increasingly important to understand the choices consumers make and how those decisions affect the health of a planet with limited resources. In a new study, published in the journal Young Consumers, Helm and her colleagues explore how materialistic values influence pro-environmental behaviors in millennials(千禧一代), who are now the nation's most influential group of consumers. 

The researchers focused on two main categories of pro-environmental behaviors: reduced consumption, which includes actions like repairing instead of replacing older items; and "green buying," or purchasing products designed to limit environmental impacts. The researchers also looked at how engaging in pro-environmental behaviors affects consumer well-being.

More materialistic participants, the researchers found, were unlikely to engage in reduced consumption. However, materialism did not seem to have an effect on their likelihood of practicing "green buying." That's probably because "green buying," unlike reduced consumption, still offers a way for materialists to fulfill their desire to get new items, Helm said.

Study participants who reported having fewer materialistic values were much more likely to engage in reduced consumption. Consuming less was, in turn, linked to higher personal well-being and lower psychological suffering. Green buying—which may have some positive environmental effects, although to a smaller degree than reduced consumption—was not found to improve consumer well-being, Helm said.

The take-home message for consumers: "The key is to reduce consumption and not just buy green stuff. Having less and buying less can actually make us more satisfied and happier," Helm said. "If you have a lot of stuff, you have a lot on your mind," she said. "For example, it requires maintenance and there's a lot of burdens of ownership, and if you relieve yourself of that burden of ownership, most people report feeling a lot better and freer."

Helm and her colleagues additionally looked at how materialism affects millennial consumers' proactive financial behaviors, such as budgeting and saving. Examining financial behaviors alongside pro-environmental behaviors provides a picture of how young adults proactively deal with resource limitations in two contexts: environmental and financial, Helm said.

As expected, Helm and her colleagues found that those who reported having more materialistic values engaged in fewer proactive financial behaviors than their less materialistic counterparts(对应的人). The researchers also found that, consistent with previous studies, proactive financial behaviors were associated with better personal well-being, life satisfaction and financial satisfaction, as well as lower psychological suffering.

Understanding how materialistic values impact consumer behaviors, and how those behaviors in turn affect personal and environmental well-being, is important, Helm said. However, she acknowledges that for many consumers, shifting behaviors to be more financially proactive and consume less will be challenging.