You can tell a lot about people by looking at their hair – not just whether they brush, spray or blow-dry. Scientists have found a way to use hair to figure out where a person is from and where that person has been. The finding could help solve crimes, among other useful applications.

    Water is central to the new technique. The liquid makes up more than half an adult human's body weight. Our bodies break water down into hydrogen(氢) and oxygen. Atoms of these two elements end up in our tissues, fingernails, and hair.

    But not all water is the same. Hydrogen and oxygen atoms can vary in how much they weigh. In the case of hydrogen, for example, there are three types according to their weights. Each type is called a hydrogen isotope（同位素）. And depending on where you live, tap water contains different isotopes.

    Can hair record this information? That's what James R. Ehleringer, an environmental chemist at the University of Utah, wondered. To find it out, he and his colleagues collected hair from hair stylists in 65 cities across the United States. Even though people drink a lot of bottled water these days, the researchers have found that people's hair has the same isotopes as found in local tap water. That's probably because people usually cook their food with the local water.

    Authorities can now use the information to analyze hair samples from criminals or crime victims and narrow their search for clues. For example, one hair sample used in Ehleringer's study came from a man who had moved from San Francisco to Salt Lake City. As his hair grew, it reflected his change in location.

    Do you know an outstanding junior high or high school teacher, coach, guidance counselor, librarian，or headmaster? Nominate (提名)that special teacher you'll always remember and give him/her the chance to be recognized in a famous national magazine through "Educators of the Year Contest"!

Prizes

    Cash awards will be given to those from across the country who are given the honor of Educators of the Year. Besides, your winning essays will also be published in our magazine.

Guidelines

    We will only consider essays written by teens, and nominations must be for junior high or high school educators only. Elementary school educators are not suitable.

    Convince us your educator is special. Tell us about his or her style of teaching, his or her role in school activities, and community service. What has your educator done for the entire school, your class, for you or another student? Give examples with specific details. Keep your essay between 200 and 1,000 words. Remember to include the first and last name, position, and school of your educator in your essay.

Don't forget to submit (提交)your essays through our website. You can also read our submission guidelines for more information on this website.

The Deadline

    The deadline for submitting your essays is December 30. Your essays are accepted and will appear in our magazine all over the year. Winners will be made public after the January issue is published.

    The smallest kids on Earth are much smaller than you or your baby brother or sister. They're even smaller than the hairs on your head. We call them “NanoPutians”(纳米小人). Also known as NanoKids, the NanoPutians aren't real people. They are actually tiny molecules (分子) made to look a little bit like people.

    James Tour invented the NanoPutians as a way to teach kids about nanoscience, which refers to the study of things that are smaller than about 100 or 200 nanometers. “The exact size is less important than the possible applications of working with such tiny things,” Tour says, “Nanoscience is the study and development of the small so that it will affect the large.”

One of the goals of the research is to control individual atoms. Carbon, hydrogen, oxygen, and other types of atoms are the building blocks of the universe. They make up planets, rocks, people, trees, CDs — all the stuff out there. “Most things that people build come together in a top-down way”, Tour says. If you want to make a table, for instance, you cut down a big tree, make wooden boards, and hammer them together. Nature, on the other hand, builds things from the bottom up. When atoms join together they make molecules. Each molecule has a certain shape, and a molecule's structure determines what it can do. Molecules can make them come together to make a cell — or a tree.

    Tour and his co-workers turned these molecular structures into cartoon figures and made an animated(动画的) science video about the little people, set it to music and started showing it to kids in school while talking about how exciting research on small things can be.

    “Learning about the NanoKids has opened up a world of possibility for real kids who ordinarily would rather not study biology, chemistry or physics.” Tour says. When you look closely enough, the really small can be really cool.

    It's no secret that your personal characteristics directly affect how you interact with the world-but you might be surprised at just how deep it goes. Experts think that your personality can even affect how you exercise and influence what sports are suitable for you.

    Highly Sensitive

    Highly sensitive people may be more uncomfortable with group exercise classes or team sports where they feel their every move is being observed. Additionally, they may feel more upset over an ineffective or poor workout, says researcher Elaine Aron.

For such people, individual or non-competitive activities like biking, running and hiking are ideal.

    Type A Personality

    Type A individuals often have an "all or nothing approach" to exercise. This personality type is known for sticking closely to their plan, not to mention being super competitive. However, this can cause them to stick too closely to a fitness routine, which means they might try to push past an injury.

    To get better exercise results, Type A people need to be aware that following an exercise plan too strictly may limit their progress. They should be more flexible and listen to their body, especially when they are in pain.

    Type B Personality

    This laid-back group may get too lazy about their exercise plan, which prevents them from seeing results. They are often less willing to devote enough time and energy to their fitness goals, especially if exercise is something that makes them anxious.

    Type B individuals succeed in creative and co-operative environments, so team sports and group gym classes may be perfect.

    Remember, there are plenty of ways you can adapt a fitness plan to suit your needs, regardless of your characteristics. Just keep in mind what you like.

    We don't know how different our future will be in the future. We can only try to imagine it.

    At first we think about human relationship. In the year 2050, we will use computers almost every day. We will be making new friends through the Internet—even our husbands or wives will be met in this way. It will be much faster and easier for us. On the other hand, our relationships with people won't be as important as they are today—we will feel a little lonely.

    Computers will also help us in many other activities in 2050.For example, they will be used by the children at school to make their learning easier. In addition, there will be much more other machines which will play a similar role as computers, like robots which will do the housework for us.

    Spending holidays will also be completely different. Traveling to other planets or to the moon will be available for everyone. Means of transport will, of course, change, too. We will be using solar­powered cars, which will be much more environmentally friendly.

    We could expect that the faster technological progress would lead to a more polluted environment. But it isn't true. We will pay more attention to protecting the environment. And, scientists will probably find cures for many dangerous diseases, like cancer or AIDS. Therefore, our surroundings as well as health will be in better condition.

    Although we can't predict the exact changes which will be made in the world, we often think about them. We worry about our and our children's future; we have expectations, hopes as well as fears. But I think we should be rather optimistic about our future. We should be happy and believe good things will happen.

Robots have long been drawing inspiration from animals, with the creation of robot dogs or snake-shaped robots. And yet, the field of robotics is far less enthusiastic about the other kind of living things—plants. Barbara Mazzolai, an Italian roboticist owes this to a misconception about plant behavior: that they cannot move or think. "It's not true at all, " she says. To challenge this view, Dr Mazzolai and her team recently launched a machine called "FiloBot", a robot based on a climbing species. 

To survive, a climbing plant must switch between several different behaviors. In forest environments, it must first grow out of the soil and travel along the ground in search of a support to hold onto, such as a nearby tree. Once a support is located, though, the plant fixes itself around the object and then growing towards the light. To choose the best angle to grow upwards, a climbing plant uses its shoots(芽) to receive information about light and gravity. 

FiloBot has sensors on its main shoot. It can 3D-print its body with plastic and grow at a controllable rate. These functions, researchers found, enabled FiloBot to cross gaps, and find things to attach to. The lack of heavy on-board computing device means that it is light and requires minimal care, while its slow pace means that it doesn't disturb things around it, making it possible to move through a complex, unseen environment, or monitoring disaster sites. 

For now, FiloBot is still being tested. Its tendrils(卷须) have not left the laboratory. Still, it has already been employed in deconstructing plant behaviour. For example, it was long assumed that climbing plants find their supports by growing towards shade, though the exact mechanism was unclear. FiloBot could imitate this behaviour by detecting far-red light, which is typical of shaded areas, providing clues to how plants do it. 

Dr Mazzolai hopes that such projects will inspire other roboticists to take their cues from plants and develop completely new technologies.