Everyone is familiar with white fat, which serves as an energy warehouse. Many mammals also have brown fat, which has the unique ability to produce heat.

Brown fat is sometimes mistaken for a type of gland (腺), which it resembles more than white fat. It varies in color from dark red to tan. When the animal is exposed to a cold environment, the color darkens. In contrast to white fat, brown fat has numerous nerves which provide sympathetic stimulation (刺激) to the fat cells.

Brown fat is most noticeable in newborn animals, wrapped round the central organs to keep them warm. In human infants it occupies up to 5% of body weight, then declines gradually. Certain quantities of brown fat can be discovered in adult humans, especially when they are exposed to cold temperatures. Most of brown fat in adults is located in the lower neck.

Exposure to cold leads to sympathetic stimulation of brown fat cell. As in white fat, sympathetic stimulation promotes hydrolysis (水解) of triglyceride (甘油三酸脂), with release of fatty acids. In contrast to other cells, including white fat cells, brown fat cells express UCP1, which gives the cell’s mitochondria (线粒体) an ability to produce heat rather than ATP. Within brown fat cells, most fatty acids are immediately combined with oxygen in mitochondria and a large amount of heat is produced.

There is only about50gof brown fat in the neck region and it switches on and off throughout the day as it’s exposed to different temperatures or if you exercise or eat. But this capacity is much greater in young children compared with adolescents and adults.

The challenge is now to use the knowledge to find out what might switch on brown fat. If it is switched on, we can benefit from it. Brown fat produces lots of heat by burning calories. Unlike white fat, brown fat does not expand our ageing waistlines. And that’s why the race is on to find out more about brown fat, and how humans could use it to our advantage, though we would waste energy unnecessarily, and we would sweat a lot and forever be opening windows.

 If you look outside, you probably will see some kind of insect. If your first instinct is to kill it, take a moment to think about all of the benefits insects provide to the environment.

  Entomologists, scientists who study insects, estimate that there are more than 800,000 species of insects found throughout the world. Only a few hundred of these insects are considered harmful. Mosquitoes, for example, are considered harmful. They bite humans and other animals, and their bites can cause skin pain and spread disease. Desert locusts also are considered harmful because they destroy crops causing billions of dollars in damage each year.

  However, the number of helpful insect species far outweighs the number of harmful species. Some insects make up a vital part of the food chain. Many different birds, reptiles, fish and even plants eat insects. There are also about 500 insects that people in various parts of the world eat. These insects are considered delicious food and prized for their high protein, mineral, and vitamin content. Other insects produce valuable commercial products such as silk, wax, and honey.

  Of all the insects, perhaps the most important are those that travel from flower to flower and pollinate(授粉) the plants they visit. Agriculture around the world would be very different without the bees, butterflies, moths, flies and wasps that pollinate many crops. In fact, nearly one-third of the food you eat depends on plants that are pollinated by insects!

  While it is true that some species of insects harm or annoy us, you should not automatically reach for the bug spray when you come across an insect. You may be destroying one of the hundreds of thousands of insects that provides many benefits to human beings.

  A technology company is developing a lie detector app for smartphones that could be used by parents, teachers—and even Internet daters.

   The app measures blood flow in the face to assess whether or not you are telling the truth. Its developers say that it could be used for daters wanting to see if somebody really is interested in them. Parents could use it on their children to see if they are lying and teachers could work out which of their pupils are honest.

   The app is being developed by Toronto startup NuraLogix and the software is called Transdermal Optical Imaging. The idea is that different human emotions create different facial blood flow patterns that we have no control over. These patterns change if we are telling the truth or telling a lie.

   Using the footage(拍摄的片段)from the smartphone camera, the software will see the changes in skin colors and compare them to standardized results. A study from last year found that anger was associated with more blood flow and redness while sadness was associated with less of both.

   Developmental neuroscientist (神经病学家) Kang Lee, who has been researching the field for 20 years, said. "It could be very useful, for example, for teachers. A lot of our students have math anxiety hut they do not want to tell us. because that's embarrassing." bee remarked that the technology would not replace lie detectors used in a court of law. He said, "They warn the accuracy to he extremely high, like genetic tests, so a one-in-a-million error rate. Our technique won't be able to achieve an extremely high accuracy level, so because of that I don't think it's useful for the courts." He added that it would be a few years before the app is available to consumers.

C

Hospital emergency rooms have to treat fingers all the time. Without treatment, a bad cut can lead to permanent damage. But how should a person know when a bleeding cut is serious enough to require medical attention? We asked Dr. Tim Brown, a doctor of the emergency department.

First, the medical term for a cut or tear in the skin is a laceration(撕裂伤). The length is usually not as important as the depth. He says a long cut on a finger can likely be treated without a visit to a doctor if the wound is not very deep. "If you have a short but deep laceration where there's been a structure underneath that's been damaged -- a tendon, a nerve, a blood vessel -- it may, in fact, need professional attention."

Some injuries -- like a fingertip that gets cut off -- might even require surgery to repair. "That requires a specialist to either file down the bone or reattach the fingertip. More often, filing down the bone is what is done because reattaching a fingertip is often not successful."

How a wound bleeds can be a sign of how serious it is. Minor cuts usually produce what is known as venous bleeding. This means the blood flows steadily from the injury. The bleeding will often stop when pressure is put on the wound. In most cases holding direct pressure with a clean cloth for four to five minutes should stop the bleeding. With a cut finger, holding the hand above the heart can reduce the loss of blood. But if a cut appears to be pumping blood out with some force, this may be a sign of arterial(动脉) bleeding. This kind of injury should be treated by a medical professional as soon as possible.

Even a cut that does not require medical attention must be kept clean to prevent infection. Small cuts should be cleaned gently with clean water. Use a washcloth to clean the area if the wound is dirty. Cuts should be covered with a clean, dry bandage.

Since the Internet has come into homes, the daily life has never been the same again. But the thing that worries most of us is that we can get viruses from the Internet. But can we catch viruses on our cell phones? A new study in the journey Science says yes, but the spread of such mobile software that can bring harm to our cell phones won’t reach dangerous levels until more cell phones are on the same operating system.

Computers are easily attacked by viruses because they share data, especially over the Internet. Of course, nowadays, more people are using their cell phones more and more frequently. They use them for emailing, text messaging and downloading troublesome ring tones, etc. so it is obvious that cell phone viruses are a threat , as well.

Scientists used nameless call data from more than six million cell phone users to help model a possible outbreak. And they concluded that viruses that spread from phone to phone by Bluetooth are not muc h concerned, because users have to be in close physical relation for their phones to “see” one another. However, viruses that spread through multimedia messaging services can move much faster, because they can come in disguise (伪装), such as a cool tune sent by a friend. The good news is that to be effective, these viruses need their victims to all use the same operating system, which not enough of us do. Because there is no Microsoft operating system for mobile phones, yet. Thank goodness.

   B

     Many people have long dreamed of being able to fly around as simply as riding a bicycle.  Yetthe safety and strength of a flying bike was always a big problem.Over the past 10 years, developments in technology have moved the dream of personal flying vehicles closer to reality. Now, two groups of inventors say such vehicles may be available very soon.

      Grant Stapleton from Malloy Aeronautics says the Hoverbike, which is able to get in and out of small spaces very quickly, will be a truly personal flying vehicle.  "It can be moved across continents very quickly because it can be folded and packed," he adds.

      Mr. Stapleton says safety was the company's main concern when developing the Hoverbike. He ays the designers solved the safety issue by using overlapping rotors  (折叠旋翼)  to power the vehicle. The company is testing both a one-third size model and a full-size prototype  (原型)  of the Hoverbike.

     Inventors say their Hoverbike will most likely be used first by the police and emergency rescue teams.

     In New Zealand,  the Martin Aircraft Company is also testing a full-size prototype of its personal flying bike, called Jetpack. It can fly for more than 30 minutes, up t0 1,000 meters high and reach a speed of 74 kilometers per hour.

     Peter Coker is the CEO of Martin Aircraft Company.  He said Jetpack "is built around safety from the start, " In his words, "reliability is the most important part of it.  We have safety built into the actual structure itself, very similar to a Formula One racing car. "

     Jetpack uses a gasoline-powered engine that produces two powerful jet streams.  Mr. Coker says it also has a parachute (降落伞) that can be used should there be an emergency. "It opens at a very low altitude and actually saves both the aircraft and the pilot in an

emergency," he adds.

C

       Whether or not you believe Professor Stephen Hawkingˈs alarming theory that building a “strong” artificial intelligence (AI) could lead to the end of the human race, it’s clear that AI is reaching the point where soon it will affect almost every aspect of how we work with computers. We must get used to computers that talk back.

       Last year, investment bank Deep Ventures attracted much media attention when it announced that it had appointed an AI computer to its board of directors to help make important business decisions. What actually happened was that the company used a program called VITAL to analyse potential investments (授资) in different businesses. But VITAL doesnˈt attend board meetings or vote — it’s just a program. While itˈs not quite the evil robot we see in science fiction movies, it shows us how far computers and AI have advanced.

       Soon AI systems will be driving our vehicles, interpreting our facial expressions as we perform complex tasks, translating our voices into different languages and building other machines for us in factories around the world. But they wonˈt look like us or pretend to be human.

       In the new film Ex Machina, a computer scientist is asked to assess whether a beautiful human-looking robot called Ava has human intelligence. I wonˈt spoil the film for you, but it occurred to me that one of the reasons we believe other human beings are conscious and have intelligence is that we’re told they are all .the time. Indeed, if you stopped believing other people have minds, you would quickly find yourself unable to function in the world.

       Google’s Eric Schmidt argues that we shouldnˈt worry about AI, and that we need instead to redesign our education systems so that we learn how to get on with the machines. As powerful computer-based intelligences continue developing, we must let go of the belief that only humans have intelligence and consciousness. Just as we have accepted the reality that the self-awareness that makes minds possible exists within the animal world, we may soon accept that it can also exist within the machine world.

Learning about the environment is very important. There are many good books that will help you learn. To get started, ask your teacher or a librarian for some suggestions. You can also look at some good websites with information about the environment and climate change. Climate change may be a big problem, but there are many little things we can do to make a difference.

Driving a car or using electricity is not wrong. We just have to be smart about it. Some people use less energy by carpooling. For example, four people can ride together in one car instead of driving four cars to work. Whenever we use electricity, we put greenhouse gases(气体) into the air. By turning off lights, the television and the computer when they aren’t needed, you can help a lot.

Don’t buy products that use too much energy. Some products, like certain cars, are made specially to save energy. These don’t pollute as much, either. Products like computers, TVs, and VCRs with the ENERGY STAR label(标签)R are made to save energy. Buying products with these labels will help protect the environment.

Buy recyclable products instead of (代替) non-recyclable ones. Recyclable products are usually made out of things that have already been used. It usually takes less energy to make recyclable products than to make new ones. So when you go shopping, look for the recycle mark on the package—three arrows that make a circle.The less energy we use, the better.

D

Strange fingertips

We all know well the prune-like fingers we get when we are in the bath. Most people think it’s caused by water making the skin in our fingers bigger. In fact it could be an evolutionary (进化的)feature caused by a reaction in our body’s central nervous system. Rather than the skin getting bigger, fingertips actually shrink when they wrinkle(起皱纹), because the blood vessels(血管) inside them contract. The lines could have evolved in our ancestors as they collected food from wet vegetation or streams.

Dr Tom Smulders wanted to test the theory suggested by Mark Changizi in 2011, which said that wrinkled fingers were an evolutionary adaptation. Like treads on tyres, Changizi said that wrinkles served the function of removing water from between the fingers and objects, making it easier to pick things up.

Perfect student project

Smulders saw that it should be easy to prove that wrinkled fingers were better at gripping in wet conditions and it was an ideal student project. He explains, “We had the idea of timing how long it takes to move marbles from one container to another, between thumb and index finger. The people in the experiment did that underwater or not underwater, with wrinkled fingers or not wrinkled fingers – so one person did all four conditions.”

They found that people are in fact better at moving objects from underwater with wrinkled fingers than with normal fingers.

Adaptation to environment

Whether that means that wrinkled fingers are an adaptation is open to question; it could be a side effect of something that evolved for a different reason. The research suggests that there may be a loss of sensitivity in our hands, which explains why our fingers return to their normal state when not under water.

  It has often been suggested that the ocean, rather than space ,is the true final frontier. From the extremely high pressure that threatens human lives to unknown geography that can injure people and machines alike, various things make sending human explorers hazardous. The deepest section of the ocean is the Marianas Trench, which begins at 20,000 feet. It has points where the depth approaches seven miles and the pressure reaches eight tons per square inch. That’s why the Marianas Trench remains largely unexplored to this day.

       Even knowing about all of the difficulties, however, some scientists feel the draw of the ocean’s depths. The environment, unfriendly though it may be to man, is friendly to others, allowing for the development of quite a few creatures not found anywhere else on the planet. The first exploration of the Marianas Trench’s floor took place in 1960. Since then, the cost of sending people back has been seen as too great.

       The goal, then, has been to find a way to learn about this frontier without risking the lives of explorers. One way that scientists have discovered new information is through the use of sonar. As sonar technology — a sound-based method of determining surroundings — has improved, scientists have been able to get more accurate maps of the ocean’s floor.

       Another method of exploration that has become more common in recent years is to use machines that have no people working inside them. These include underwater cameras and robots. The latter have become increasingly common in recent years.

       Although most of the robots used so far have been attached to a larger device with people aboard, the day when the robots can move independently may not be far off. As technology is being advanced, it seems quite likely that automatic robots will become more competent ocean floor explorers than humans.