Love to sink into your chairs and relax when you get to school? Then you will not be happy to hear that schools all over the world are seriously considering exchanging traditional desks for ones with no seats at all — Yes, that means you will be encouraged to stand through those already too long math and science lessons! Why would anyone even think of putting kids to such cruelty? Experts say it improves their health and helps fight obesity. While that may seem a little far-fetched (牵强的), the officials at the few schools around the world seem to agree.

    Among them are educators from the College Station Independent School District in Texas, who recently completed aweek-long experiment involving 480 students across three elementary schools. The 374 kids that agreed to participate in the study were provided with adevice that helped record step count and calorie consumption over the entireperiod.

    All 25 teachers involved in the study reported that students appeared to be more alert and concentrate better, when allowed to stand. The one thing that did surprise the researchers was that younger kids were more willing to stay standing than kids in higher grades. They believe this may have something to do with the fact that after years ofbeing asked to “sit still”, older kids have a harder time adjusting to this unexpected freedom.

    American schools are not the only ones reporting success with stand-up desks. Four Catholic schools in Perth,Australia, which have been testing them since October 2013, have seen similar results. In May 2014, Grove House Primary School in Bradford, West Yorkshire,became Europe's first test one, with a seven-week trial that involved the useof desks made by Ergotron in their fifth-grade classrooms. While official results are not out yet, early reactions from both teachers and students, have been extremely encouraging.

    The findings of these studies and othersdone previously, all seem to mean that allowing kids to move around in classrooms is a win-win for students and teachers — it helps kids get healthier and provides educators with a more engaged audience.

    Superfast double­decker (双层) trains will be taking passengers from London to six big cities in the UK by 2033. The first phase (阶段) linking London to the West Midlands with a connection to HS1 is expected to open in 2026, and the second  phase to Manchester and Leeds in 2032.

    The government set out a plan for the high­speed rail network in 2012. When the project is finished, it will take less time to get to London from major cities like Birmingham, Manchester and Leeds. Traveling at a speed of up to 250 mph, passengers will be able to come and go from Birmingham to London in 49 minutes, reducing the journey time by almost half from one hour and 24 minutes.

    A journey from Birmingham to Leeds will be reduced from two hours to 57 minutes and a journey from Manchester to London will be reduced from two hours and 8 minutes to one hour and 8 minutes.

    “HS2  is an  important  part of transport's  low­carbon future,” Transport  Secretary Justine Greening said. Some people aren't happy about the plan, though. HS2 will cost around ￡33 billion. It will also be built near some towns and villages, disturbing the people that live there.

    But the Chancellor of the Exchequer (财政大臣) George Osborne thinks it will help build the future for Britain. “It's a long­term decision，” he said.

    HS2 is designed for everything around the needs of the passengers. It will provide a new and exciting travel experience. There will be plenty of room, intelligent ticketing, a good service and high quality comfort and access to trains. This is a transport network for the new century and beyond.

    Dry Ice is a unique substance which has many uses. Essentially, dry ice is frozen CO2. The first report of what we now call dry ice came from the French chemist Charles Thilorier in 1834. In 1924, the Drylee Corporation of America named the solid form of CO2 as "Dry Ice", which is what it is popularly called today.

    At normal atmospheric pressure, CO2changes directly from solid to gas. It skips the liquid phase（阶段）which makes regular ice wet. Frozen CO2is also much colder than regular ice. But regular ice freezes at 32 degrees Fahrenheit, CO2 changes from gas to solid at -109.3 degrees Fahrenheit. This extremely cold temperature makes it very dangerous to handle with bare hands. It can cause frostbite in a very short period of time.

    Dry ice has been used for a variety of purposes throughout the past century. Its primary use is to refrigerate food when electrical refrigeration isn't available. Through the process of sublimation (when CO2 changes from solid to gas), it can maintain cold food for a long time.

    If you've ever been to a play and seen heavy fog on the ground, it is likely that you have seen dry ice in action. This effect can be achieved because CO2 is heavier than air, so evaporated （挥发的）CO2 will sink and accumulate on the ground.

    Another interesting use for this substance is to bait（诱杀）insects like mosquitoes. These insects have sensors which guide them to CO2. They find the high concentration of CO2 in dry ice quite attractive.

    Mars has long been a mystery for human beings. We have been looking for evidence of life on Mars. In the 1960s scientists guessed that the polar ice cap of Mars was made of frozen CO2. More recent observations have shown that while the topmost layer consists of frozen CO2, the most of it is probably regular frozen water.

    "A photograph that one has taken of oneself, typically with a smart phone or webcam and uploaded to a social media website" is the definition of "selfie" in the Oxford English Dictionary. In fact, it wasn't even in the dictionary until August of last year. It earned its place there because people are now so obsessed with (对……痴迷) selfies—we take them when we try on a new hat, play with our pets or when we meet a friend whom we haven't seen in a while.

    But is there any scientific explanation for this obsession? Well, you should probably ask James Kilner, a neuroscientist(神经系统科学家) at University College London.

    Through our lifetime we become experts at recognizing and interpreting other people's faces and facial expressions. In contrast, according to Kilner, we have a very poor understanding of our own faces since we have little experience of looking at them—we just feel them most of the time.

    This has been proved in previous studies, according to the BBC.

    Kilner found that most people chose the more attractive picture. This suggests that we tend to think of ourselves as better-looking than we actually are. To further test how we actually perceive our own faces, Kilner carried out another study. He showed people different versions of their own portrait—the original, one that had been edited to look less attractive and one that was made more attractive—and asked them to pick the version which they thought looked most like them. They chose the more attractive version.

    But what does it say about settles? Well, isn't that obvious? Selfies give us the power to create a photograph—by taking it from various angles, with different poses, using filters (滤色镜) and so on—that better matches our expectations with our actual faces.

    "You suddenly have control in a way that you don't have in non-virtual(非虚拟的) interactions," Kilner told the Canada-based CTV News. Selfies allow you "to keep taking pictures until you manage to take one you're happy with", he explained.

    Hotshot jet pilots are no match for cliff swallows. The birds rocket over bridges and skim over lakes, rushing forward at accelerations that would knock an Air Force. By tracking these contests with high-speed cameras, a new study gives the first, in-depth peek into avian aerodynamics (鸟类空气力学) in the wild. "The findings may even provide insight into how to design better micro air vehicles-tiny drones. This technology will be brilliantly useful," says biomechanics expert Jim Usherwood of the United Kingdom's Royal Veterinary College in Hatfield. "High-resolution field studies like this have never been done before for birds."

    For cliff swallows, the trouble starts when they return from wintering in South America to their summer homes in North America. After arrival, they seek out their old mud nests—usually located under concrete bridges and freeways-and start rebuilding their homes. But rather than hunt down a fresh supply of mud, some swallows prefer stealing supplies from their more hardworking neighbors. Others take things further and will even lay an egg or two in their neighbor's nest before taking off.

    Battles in the air follow if the invaders are caught in the act, and a new study takes advantage of these fights to learn how birds perform high-speed maneuvers (演习). The team placed three cameras along a North Carolina lake crossed by a highway bridge that houses several cliff swallow nests and waited for the battles to commence.

The team was surprised to learn that most of the time, chasers copied the move of fleeing invaders. Swallows also pull very hard turns to escape an enemy, with one extreme case reaching 7.8 gravity. Fighter pilots usually pass out at about 5 or 6 gravity, which is why these experiments have earned interest, and partial funding, from the Office of Naval Research. The Navy may use the findings to build better guidance systems for micro air vehicles. However, the swallows' biomechanics are complex, and now the team is simply trying to collect a few tricks.

    Imagine your body is like the house you live in. Every day, your family creates rubbish. The rubbish builds up until it is put out for the weekly garbage collection.

    Now, say you put three bags of garbage out, but because one of the collectors was away sick, only two bags are collected. You take the leftover bag inside to be put out again next week. The following week you put on another three bags, plus the leftover bag from last week. But again, only two bags are collected. Imagine this cycle is repeated over the following weeks.

    This is a simple description of what happens to your body when your kidneys (肾脏) don't work efficiently. Your body is not thoroughly emptied of waste products. Other areas of the body such as blood pressure and red blood cell production are affected and the insidious process that may lead to kidney failure begins.

    It's not uncommon for people to lose up to 90% of their kidney function before developing any symptoms. There may be no warning signs. This makes early detection (诊查)difficult.

    Kidney's main job is to remove toxins (毒素) and unwanted water from our blood. Every day our kidneys clean an average of 200 litres of blood. Kidney failure may be a gradual and silent process, going unnoticed because there is no obvious pain.

    Research shows that more than 35% of the patients requiring dialysis (透析) do not see a kidney specialist before they have to do so. Some risk factors for kidney disease such as age and genetic make-up are out of our control; however, some changes in lifestyle may help prevent kidney damage. Two major risk factors for kidney disease, diabetes (糖尿病) and high blood pressure, have been on the rise over the last few decades. Both conditions are chiefly affected by being overweight and not getting enough exercises, which are the potential (潜在的) risk factors for the kidney disease.