Some unwelcome visitors from North America have been turning up in the waters off the coast of Great Britain.

    North American lobsters (龙虾) have been found in the North Sea (between Great Britain and Northwest Europe), far from their own habitat. The lobsters usually live along the eastern coast of Canada and the United States.

    It is impossible that the lobsters could have made the 5,600-kilometre journey on their own. They were probably brought to Britain and then got away from containers. Some of the lobsters that were caught had elastic bands (松紧带) holding their legs shut, like lobsters that are kept in containers in stores or restaurants.

    Many may have been “set free” from some ships passing through the area. Sometimes passengers order a live lobster from a tank in the dining room and then ask the waiter to throw it overboard instead of cooking it.

    According to official records, 26 North American lobsters have been caught in waters off Great Britain since 1988. However, it is believed many more have been found but not reported.

    It is against the law to let North American lobsters come into British waters. If they settle down in European waters, it would be bad for the local lobsters. The two live in the same place and eat the same food. But North American lobsters are larger, stronger and more aggressive (好斗的) than European lobsters, and they produce young more quickly.

    As a result, they could take food and space away from the local lobsters, and from other types of shellfish that live in the same area. These lobsters may also carry diseases that could harm the local lobsters.

    Unlike most other holidays, the history of April Fools' Day. Sometimes called All Fools' Day, is not as the totally clear. The only point in time that can be agreed on as the beginning of this tradition was 1582,in France. Before that year, the New Year was celebrated for eight days, beginning  on March 25.The reform of the calendar celetxration reached the highest point on April l_With the riform of the calendar under Charles 1X,the Gregorian calendar (公历, 阳历）was introduced, and New Year's Day was moved to January 1.

    However, because in those days communications were not as developed as they are today, many people did not receive the news for several years. Some people refused to accept the new calendar and continued to celebrate the New Year on April, These backward people were considered “foots” by other peopk. They were often sent on “fools” errands (徒劳无益的工作)or were made the taragets of jokes.

    This developed, over time, into a tradition of playing a trick on someone on the first day of April. The tradition eventully spread to England and Scotland in the eightreenth century. It was later introduced to the American colonies of both the Britain and Francc.April Fools' Day thus developed into an  international fun feast,so to speak,with different nationalities specializing in their own kind of humor at the expense of their friends and families.

    Most people know precious gemstones (宝石) by their appearances. An emerald flashes deep green, a ruby seems to hold a red fire inside, and a diamond shines like a star. It's more difficult to tell where the gem was mined, since a diamond from Australia or Arkansas may appear the same to one from the Democratic Republic of the Congo. However, recently, a team of scientists has found a way to identify a gemstone's origin.

    Beneath the surface of a gemstone, on the tiny level of atoms and molecules（分子）, lie clues (线索) to its origin. At this year's meeting of the Geological Society of America in Minneapolis, Catherine McManus reported on a technique that uses lasers (激光) to clarify these clues and identify a stone's homeland. McManus directs scientific research at Materialytics, in Killeen, Texas. The company is developing the technique. “With enough data, we could identify which country, which mining place, even the individual mine a gemstone comes from,” McManus told Science News.

    Some gemstones, including many diamonds, come from war-torn countries. Sales of those “blood minerals” may encourage violent civil wars where innocent people are injured or killed. In an effort to reduce the trade in blood minerals, the U.S. government passed law in July 2010 that requires companies that sell gemstones to determine the origins of their stones.

    To figure out where gemstones come from, McManus and her team focus a powerful laser on a small sample of the gemstone. The technique is called laser-induced breakdown spectroscopy. Just as heat can turn ice into water or water into steam, energy from the laser changes the state of matter of the stone. The laser changes a miniscule part of the gemstone into plasma, a gas state of matter in which tiny particles（微粒）called electrons separate from atoms.

    The plasma, which is superhot, produces a light pattern. (The science of analyzing this kind of light pattern is called spectroscopy.) Different elements produce different patterns, but McManus and her team say that gemstones from the same area produce similar patterns. Materialytics has already collected patterns from thousands of gemstones, including more than 200 from diamonds. They can compare the light pattern from an unknown gemstone to patterns they do know and look for a match. The light pattern acts like a signature, telling the researchers the origin of the gemstone.

    In a small test, the laser technique correctly identified the origins of 95 out of every 100 diamonds. For gemstones like emeralds and rubies, the technique proved successful for 98 out of every 100 stones. The scientists need to collect and analyze more samples, including those from war-torn countries, before the tool is ready for commercial use.

    Scientists like Barbara Dutrow, a mineralogist from Louisiana State University in Baton Rouge, find the technique exciting. “This is a basic new tool that could provide a better fingerprint of a material from a particular locality,” she told Science News.

    The new mayor of Hillsdale, Michigan, is a man of the people, ready to listen to their problems, but only until 6 p.m. Then he has to do his homework. Michael Sessions, 18, beat former mayor Douglas Ingles, 51, by just two votes and became the new mayor of Hillsdale. He is America's youngest mayor.

    As Sessions was too young to enter the election in the spring of 2005, he registered to vote on Sept, 22, one day after his 18-year-old birthday. The day after that he started his write-in campaign, which means he should persuade voters to remember his name and write it by hand on the voting ballots（选票）.

    To help get his name known, Sessions earned＄700 by selling apples over the summer. He spent the money on posters and put them on the Hillsdale's lawns.

    Sessions' month-long campaign included going door to door, explaining his ideas of the town's future in the kitchens of his neighbors. "They'd look at me, and say‘How old are you again? How much experience do you have?' And I say ‘I'm still in high school', " he said. Sessions promised Hillsdale's voters he would renew local economy. “I was hopeful the whole time, ” he explained. One day he spent so long out on the streets knocking on the doors that he ended up in a hospital emergency room.

    Sessions said that his schoolwork will not get in the way of his job as a mayor. “From 7:50 a.m. to 2:30p.m., I'11 be a student. From 3 to 6, I'11 be the mayor of Hillsdale," he said.

    “He did a very brave thing that couldn't have been easy for him to do, "said Jack Vettel, a councilman in Hillsdale, a city of 8,200 about 75 miles southwest of Detroit. "He does care about this town. He's been here all his life.”

    Sessions will receive＄3, 600 a year during this four-year term, and will work out of his bedroom since the town does not provide the mayor with an office.

    New Zealand's chief conservation (环保) officer, Lou Sanson, caused an argument in October by suggesting that it should be time to start charging tourists for entering national parks. New Zealanders are keen fans of these parks. Many would be annoyed at having to pay. But many also worry about the incoming foreign tourists who have been seeking the same fun.

    In 2016 New Zealand hosted 3.5m tourists from overseas; by 2022 more than 4.5m are expected every year — about the same as the country's population. Tourism has become the biggest export. The national parks, which make up about one-third of the country, are a huge draw. About half of the foreign tourists visit one. They are keen to experience the natural beauty promised by the country's "100% Pure New Zealand" advertising campaign (and shown off in the film adaptations of "The Lord of the Rings" and "The Hobbit", which were shot in New Zealand's breath-taking wilderness).

    But for every happy foreign couple posting for a selfie next to a tuatara (楔齿蜥) there is a New

    Zealander who remembers the way things used to be — when you could walk the tracks without running into crowds at every clearing. Many locals now wonder why their taxes, as they see it, are paying for someone else's holiday. Mr. Sanson would seem to agree. Entry fees could be used to upgrade facilities such as car parks and trails. A charge could also help reduce numbers at some of the popular locations by making it cheaper to use lesser-known, but no less beautiful, trails far away from home.

    Some are not so sure it would work. Hugh Logan, a former chief of conservation for the government who now runs a mountain climbing club, worries it would cost too much to employ staff to take money from hikers at entrances. It would also be difficult to prevent tourists from entering the parks without paying.

    Some argue that it would be easier to charge visitors a "conservation tax" when they enter the country. The Green Party, the third-largest in parliament (议会), says that adding around NZ$18 ($12.50) is still acceptable to foreign tourists. But some travel companies don't quite agree with the idea. They note that tourists already contribute around NZ$1.1bn through the country's 15% sales tax. Better, such firms say, to use foreign tourists' contribution to this tax for the protection of the parks.

    Among the fiercest critics of a charge are those who point out that free access to wilderness areas is an important principle for New Zealanders. It is documented in a National Parks Act (法案) which inspires almost constitution-like devotion among the country's nature-lovers. Mr. Sanson has a rocky path ahead.

    Runners never forget crossing the finishing line at their first marathon, and that will be especially true for Mike Kohler. When Kohler crossed the starting line in Fargo last Saturday, he thought he was going to run 13.1 miles, his first half marathon. Six hours later, he had "mistakenly” completed his first full marathon, 26.2 miles.

    Kohler, a 26-year-old plumber (水管工) who now lives in West Fargo, had lined up for the half marathon that he hoped to complete in 150 minutes. He didn't realize he was in a starting fence with the full marathoners. Several miles later, Kohler began to realize he was on the course for the full marathon. "The 8-mile mark was when I figured out that I had made a mistake," he said. "Between then and 13.1, I debated with myself about what I should do."

    At some point — he doesn't remember when — he doubled down on the distance. "After I decided I was going to keep going, the thought of quitting didn't come back. Run, walk, or crawl, I wanted to finish," he said.

    Until Saturday, Kohler's longest race was a 10-kilometer run, just over 6 miles. Even the most casual marathoners do a training run of 18 miles before the race. From his experience, he said he learned one thing: sometimes people can do more than they think they can.

    After his long race, he went right back to work, put in a 10-hour day and then boarded a flight to Scotland for a vacation. "I was pretty sore, but I found the more I kept moving, the less sore I was, so I tried my best to go about life normally — minus running,” Kohler said from Glasgow. "I needed a break from that for a bit."

    Not for too long, though. He's already considering the Bemidji Blue Ox Marathon in October.