The St. Louis Post-Dispatch reported that the St. Louis Outlet Mall is expanding its restrictions on unaccompanied teenagers. In 2006, a parental-escort (陪同)policy was established: on Fridays and Saturdays starting at 6 p.m., anyone under 17 that isn't accompanied by a guardian who is at least 21 years old will be kicked out of the mall. It was around this time that other malls around the U.S. likewise banned unaccompanied teens during certain evening hours.

Starting from this Friday, the St. Louis Outlet Mall is pushing its parental-escort rule back to 3 p.m. on Fridays and Saturdays. Similarly, the Mall of America expanded its parental-escort policy during the recent holiday shopping season. Normally, the policy bans kids under 16 without guardians(监护人) from 4 p.m. until closing time just on Fridays and Saturdays. But because of a fight in the mall involving dozens of young people that took place on Dec. 18, 2012—- a weekday, the policy was broadened to include peak 2013 holiday shopping hours, including Thanksgiving Day and all of the Christmas week.

    Teen disturbances in other malls may cause more shopping centers to introduce or expand parental-escort policies. The Indianapolis Star noted that two incidents in 2013 in area shopping centers raised the possibility that Indianapolis malls might need to consider banning unaccompanied teenagers.

   Obviously, such bans are aimed at stopping violence and other outbursts involving teenagers. More importantly, from a purely business perspective, these bans aim to attract shoppers who might otherwise be hesitant to go to the mall because of concerns about violence and outbursts involving teenagers. The restrictions allow mall security officers to systematically kick out a group of people that are considered to be loud, thuggish and bad for business overall. But they attract much criticism from online communities. Some argue that teens have the right to shop without a guardian. “Not all teens are disrespectful and troublemakers,” Pamela Chapman wrote. “In fact, it's been my experience that most are good kids.”

Again, the biggest influence on stricter mall policies for teens seems to be that they're just plain good for business. Malls reported strong sales growth after they first carried out the policies six years ago. “We've had some success with the parental-escort policy, and families like shopping out here together,” the manager of the St. Louis Outlet Mall told the St. Louis Post-Dispatch . If there's one rule in retail, it's this—- if a small initiative proves successful in boosting sales, then it's all but guaranteed that a larger initiative will follow.

    Antarctica(南极洲)'s melting ice, which has caused global sea levels to rise by at least 13.8 millimeters over the past 40 years, was thought to primarily come from the unstable West Antarctic Ice Sheet(WAIS). Now, scientists have found that the East Antarctic Ice Sheet (EAIS)—considered largely unaffected by climate change—may also be melting at an unexpectedly rapid speed.

    The WAIS, whose base is below sea level, has long been considered the most likely to break down. Besides gravity, a deep current of warm water slips beneath the sheet, melting it from below until it becomes a floating shelf at risk of breaking away. In contrast, extreme cold and a base mostly above sea level are thought to keep the EAIS relatively safe from warm waters.

    But as greenhouse gases warm much of the planet, driving stronger polar winds, some scientists think warm water carried by a circular current will start to invade East Antarctica's once unassailable ice. A cooperation of more than 60 scientists last year, published in Nature, estimated that the EAIS actually added about 5 billion tons of ice each year from 1992 to 2017.

    Eric Rignot of the University of California, Irvine, and colleagues combined 40 years of satellite imagery and climate modeling and found that overall Antarctica now sends six times more ice into the sea each year than it did in 1979, with the majority coming from West Antarctica. But East Antarctica was responsible for more than 30% of Antarctica's contribution to the 13.8-millimeter sea level rise over the past 40 years. “The more we look at this system the more we realize this is fragile,” Rignot says. “Once these glaciers become unstable there is no red button to press to stop it.”

    Rignot hopes the study brings greater attention to a part of Antarctica that has traditionally been understudied. Helen Fricker, a glaciologist (冰川学家) in California, agrees. “We need to monitor the entire Antarctica and we just can't do that without international cooperation.”

    When Casey Waletich, the director of safety and operations at the Hillsboro School District in Oregon, decided to start a campaign against bullying (欺凌）in his district, he knew he had to get the students on board.

   "We knew that this had to be a student-led effort. The days of having schools do things without the involvement of the students are over，"Mr. Waletich says.

    So he got a group of students together and asked them how they would like to do things. The resulting campaign," Rethink, Redefine, Where Do You Stand?" was launched in October 2014.

    The Hillsboro campaign is just one example of how schools nationwide are increasingly turning to students to develop-anti-bullying movements designed to not just discourage bulling, but also to encourage students to get involved.

    In 2013, some 20 percent of high school students reported experiencing bullying, according to federal data on Stop Bulling gov. The figure jumps to 28 percent when middle school students are included. Some 70 percent of young people say they have witnessed bullying.

    In response to these issues, anti-bullying campaigns in which students have a central role are being conducted across the country. From West Jordan, Utah(where students participated in a three-year character-building program to stop bullying), to Lisbon, Iowa, and Goodrich, Mich, school officials report that their students are taking ownership.

   "This year I've noticed our students are already thinking about what they need to do to make Sunset Ridge an accepting, safe environment." Said Julie Scherzinger, a guidance councilor at Sunset Ridge Middle School in West Jordan." Students come up to me and ask if anyone needs help"

   "There are many reasons why having students at the center is most

important." Says Ron Avi Astor, a professor in social development at the University of Southern California in Los Angeles." Bullying takes place when adults are absent. The kids see and hear more and can go and inform adults when they aren't there to respond immediately"

   "Teaching kids to step up when someone is being bullied teaches them how to be responsible citizens." Ron Avi Astor added.

    If you're a cycling lover, you will have to pay a lot of attention to your bicycle and maintain it well, for bicycle parts are exposed to wear and tear (磨损) over time and you have to examine the bicycle to see if there are any signs of wearing such as scratches, dents (凹陷) etc. Sometimes, a part may not work because it has exceeded its life expectancy. Sometimes, you will need to find replacement parts for it to keep up the performance of the bicycle.

    Different parts of a bicycle will wear at different rates so it is very important that you have a basic understanding about the role played by each part. One of the most important parts of the bicycle is the frame. You will need to choose a frame that lasts for a very long time. Of course, you will see some paint scratches after some time. When you're selecting a frame, you have to think about the material. Aluminium (铝) frames will not rust easily, but they have a higher chance to dent. Steel frames will be hard to dent, but you will need to make sure they get a good paint job so that they won't rust.

    Wheels also experience a lot of wear and tear and you should go for a professional seller when you want to buy wheels. There are different types of wheels that you can buy, like Zipp wheels that provide more aerodynamic efficiency (空气动力学效能). Investing in new tyres instead of going for used is a good idea because you will be able to get more use out of it. The same goes for chain as there's a higher chance of a used chain breaking. You may also experience shifting problems. However, some parts of bicycles such as pedals can be used for a long time and you can find different styles.

    Other parts that you can buy used are seats, handlebars and the stem. When you are buying handlebars, you have to see if there are any dents or if they have been bent out of shape. There shouldn't be any cracks in the seat post or the handlebars. There are many shops where you can buy parts, so you will have to check the references to see how customers respond to them before you buy anything.

    The full moon climbs over the eastern horizon (地平线) and hangs like a huge orange globe in the sky. A few hours later, the moon is overhead but seems to have changed. The huge orange globe has become a small silver disk. What has happened? Why has the orange color disappeared? Why does the moon seem so much smaller and farther away now that it is overhead?

    The moon appears orange on the horizon because we view it through the dust of the atmosphere. The overhead moon does not really shrink (缩小) as it moves away from the horizon. Our eyes inform us that the overhead moon is farther away. But in this position the moon is actually closer to our eyes than when it is near the horizon.

    The change in size is a trick our eyes and minds play on us. When the moon is low in the sky, we can compare its size with familiar objects. It is easy to see that the moon is much larger than trees or buildings, for example. When the moon is high in the sky, however, it is hard to compare it with objects on earth. Compared to the vastness of the sky, the moon seems small.

    There is another reason why the moon seems to shrink. We are used to staring at objects straight ahead of us. When an object is difficult to see, our eyes have to try to focus on it. When we move our heads back to look up, we will try hard again. Looking at something from an unaccustomed position can fool you into believing an object is smaller or farther away than it is. However, scientists do not yet understand completely why the moon seems to shrink as it rises in the sky.

Washington, D.C. Bicycle Tours

Cherry Blossom Bike Tour in Washington, D.C.

    Duration Tour

    This small group bike tour is a fantastic way to see a world-famous cherry trees with beautiful flowers of Washington, D.C. Your guide will provide a history lesson about the trees and the famous monuments where they blossom. Reserve your spot before availability — the cherry blossoms—disappear!

Washington Capital Monuments Bicycle Tour

    Duration: 3 hours (4 miles)

    Join a guided bike tour and view some of the most popular monuments in Washington, D.C. Explore the monuments and memorials on the National Mall as your guide shares unique facts and history at each stop. Guided tour includes bike, helmet, cookies and bottled water.

Capital City Bike Tour in Washington, D.C.

    Duration: 3 hours

    Morning or Afternoon, this bike tour is the perfect tour for D.C. newcomers and locals looking to experience Washington, D.C.in a healthy way with minimum effort. Knowledgeable guides will entertain you with the most, interesting stories about Presidents, Congress, memorials, and parks. Comfortable bikes and a smooth tour route(路线)make cycling between the sites fun and relaxing.

Washington Capital Sites at Night Bicycle Tour

    Duration: 3 hours(7miles)

    Join a small group bike tour for an evening of exploration in the heart of Washington, D.C. Get up close to the monuments and memorials as you bike the sites of Capitol Hill and the National Mall. Frequent stops are made for photo taking as your guide offers unique facts and history. Tour includes bike, helmet, and bottled water. All riders are equipped with reflective vests and safety lights.