In recent years, remote-sensing technologies have become ordinary in archaeological fieldwork（实地考察）. Such tools for excavation produce rapid results and cause no damage to archaeological sites. They are highly accurate and usually cost effective. Here are three of the modern archaeologist's most trusted remote-sensing tools.

    As the simplest of the remote-sensing techniques that archaeologists use, aerial（空中的）photography allows experts to see aspects of a site that may be invisible from the ground, such as the way in which something such as a town, garden, or building is arranged and traces of old walls and roads. The technique involves taking photographs with conventional cameras and filming from airplanes, helicopters, hot-air balloons, or other airborne vehicles.

    Geographic Information System (GIS) contains a large amount of field data archaeologists typically collect in and around excavation sites. While in the field, archaeologists use GIS on their computers to make and manage detailed site maps, and they can combine the results of remote-sensing tests with maps of the region created with the aid of Global Positioning System. Resulting maps sort the most archeologically promising areas and display these sites three-dimensionally.

    Ranging in size from small handled models that one places against the ground to larger ones that one across a site, Ground Penetrating Radar (GPR) devices use low-power radio waves to detect changes underground. Unlike traditional radar, which broadcasts into the air and uses a dish to focus the returned waves, GPR uses a small but sensitive receiver placed directly against the ground. Depending on their needs, archaeologists can adjust radio frequencies upward for shallow sites or downward for deeper areas, though GPR devices produce the greatest definition（清晰度）when reading depths of three feet or less.

    You've probably heard people expressing alarm about the spread of 'fake news' – stories that look like news articles but describe things that never happened. Fake news is written to attract attention, to trick people so they will look foolish, or to work as satire (讽刺) making a point about society. But regardless of the source's motivation, spreading fake news embarrasses you and harms others, so follow these steps to ensure you only share real news.

    Check its grammar

    Legal news sites check their grammar carefully, so articles with many errors are usually fake. Also watch out for sentences written in all capital(大写的) letters and the use of multiple exclamation points(感叹号) at the ends of sentences. These are designed to bring about an emotional reaction, but they aren't considered professional, so trustworthy publications don't use them.

    Read the whole article

    Even in real news articles, headlines sometimes overstate or simplify the point of the article. Before reacting, read the article carefully to make sure you understand the whole context. Sometimes the claims of fake news articles become unreasonable as the article goes on.

    Consider the source

    If you've never heard of the publication, check the 'About' section on its website. Fake news sites often lack such a page, provide little information or even admit that they are fake. Also check an online article's URL; if it ends with '.com.co', it's probably a fake news site.

    Check the support

    Does the article support its claims with quotations and citations(引用)from experts? If not, don't trust it. If so, you should still look up those sources and make sure they actually say what the article claims. There are also websites, such as snopes.com, that will tell you whether the facts in online articles are accurate.

    While elephants born without tusks (长牙)are not unheard of，they normally form just 2 to 6 percent of the population. However, that is not the case at Mozambique's Gorongosa National Park, where an astonishing 33 percent of female elephants born after the country's civil war ended in 1992 are tuskless. While that may appear to be just a coincidence, Joyce Poole, an elephant behavior expert, has another theory. The researcher thinks we may be witnessing unnatural evolution of the species due to the constant hunting of elephants for valuable ivory.

    Poole says before the country's 15-year-long civil war, the 100,000-acre park was home to over 4,000 elephants. However, by the time the conflict ended in 1992, about 90 percent of them had been killed for ivory to help finance weapons (武器)and meat to feed the soldiers. Of the less than 200 survivors, over 50 percent of adult females had no tusks. Therefore, it is not surprising that the park's tuskless elephant population has grown greatly.

    This is not the first time researchers have observed a great change in the population of elephants. At Zambia's South Luangwa National Park and Lupande Game Management Area， areas which were heavily hunted in the 1970s and 1980s, 35% of elephants 25 years or older and 13% of those younger than 25 are now without tusks. A 2008 study published found that the number of tuskless females at the Ruaha National Park in Tanzania went from 10.5 percent in 1969 to almost 40 percent in 1989, largely due to illegal hunting for ivory.

    The recent ban on ivory in both the US and China should help get rid of, or at least reduce, elephant hunting. However, scientists are not sure how long it will take for elephants with a higher rate of tuskless females, to change the trend.

    It was an autumn day, and 1 was standing in the kitchen, hanging my head over the counter and trying to figure out how many calories were in a bowl of homemade yogurt and fruit. And I felt annoyed.

    I was 16, and my best friend and I had gone to our first Weight Watchers meeting. It was the trend in the mid-1980s, and even though I was an athlete, like many teen girls, I didn't necessarily like what I saw in the mirror. But after a week or so of recording every meal and snack and calculating the calories, I had had enough. I went back to my routine of chowing whatever I wanted, running and skiing, and let that be that. And it's still pretty much what I do; as long as the workouts are regular and the food is whole and balanced, my body's set point hasn't varied for years.

    The weight loss trend of three decades ago−full of scales and counting calories−has fallen away. Now fasting is popular. The ways to keep fit vary: on the 5:2 diet a person eats for five days and fasts for two days each week, while the 18:6 refers 10 fasting for 18 hours and then eating within a six-hour window each day.

    In this issue, Associate Editor Mark Barna tries to understand the science behind the fasting plans. Researchers have found that animals like monkeys age more slowly after years of eating less, and in the lab in humans, they saw improvements in a number of signs that indicate risk of some hard to cure diseases. The hope for healthy weight loss isn't over yet, but at least now the calculators don't have to be out at every meal.

    Hacking isn't just for computers and smart phones. According to a study, scientists have found a way to hack a plant's genes in order to make it use sunlight more quickly. Someday, the results could increase the number of food produced around the world.

    Scientists used tobacco plants in the study because it is easy to change the plants^' genes. Hacked plants are larger than normal plants.

    Photosynthesis is the word used to describe how plants use sunlight, water and carbon dioxide to make their own food. Scientists say this is a very slow process. Plants use less than 1 percent of the energy. But by hacking a plant's genes, the scientists were able to increase the amount of leaf growth on plants between 14 and 20 percent. Scientists hacked the plant's protective system. Normally, this system starts when a plant gets too much sunlight. When the plant senses the light, it creates more leaves. When the plant is in shade, the protective system is turned off. But the process is slow.

    The new study sped up the process by changing the plant's genes, the protective system turned on and off more quickly than normal. As a result, leaf growth on the plants scientists used in the study increased. Leaf growth on two plants increased by 20 percent, while leaf growth on a third plant increased by 14 percent. Scientists conducted the study on tobacco plants. But they think the genetic changes would produce the same results in corn and rice.

    Agriculture professor Tala Awanda said the study makes sense, but cautioned the yield（产量）might not be quite so high for conventional food crops. Still, she added in an email, "this study remains a breakthrough,"

    Many of us know about Russia's Lake Baikal from our textbooks, or by listening to Chinese singer Li Jian's hit song, Lie Baikal. But over the past decade, the world's deepest freshwater lake has been in the spotlight for an extreme sport.

    Each March since 2005, about 150 people from around the world sign up for the Baikal Ice Marathon. They come to explore the lake's breathtaking beauty and challenge themselves in unpredictable conditions. The 26-mile (41.84-kilometers) journey starts on the lake's eastern shore. In March, the ice is a meter thick and iron-hard. Runners cross this frozen surface, finishing on the western side of the lake.

    Known as the "blue eye of Siberia", Lake Baikal has exceptionally clear waters. This means its ice is almost perfectly transparent (透明的). "Seen from above, a runner on the ice looks as if he or she were jogging through space." The New York Times noted.

    The landscape might be beautiful, but it's also harsh. Strong winds blast (侵袭) across the lake and frostbite can occur within half an hour. Runners say the cold climate is what draws them. They want to test their limits.

    "When you are in such an environment, you don't have cars around you, and you don't have the noise around. I think these extreme races allow you to be alone with nature." Alicja Barahona, a 64-year-old runner from the US, told ABC news.

    The location offers some strange and unique characteristics for this marathon. The finishing line is visible from the start, but the endless white offers no progress markers. The race also ends with little fanfare (隆重的欢迎). Tourists crowding the ice are mostly addicted to snapping selfies (自拍) and just ignore the runners.

    For some runners, the absence of spectators makes the race more challenging, because it's lonely. They must fight with themselves. "You are alone on Baikal. It is your race. You are alone with yourself. All you need to do is to defeat yourself." Veronique Messina, a French runner, told the Telegraph.