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.

    What is it that makes people laugh? More than two thousand years ago the ancient Greek philosopher Aristotle defined (定义) jokes as the pleasure that results from a feeling of triumph(胜利) by showing we're better than someone else in a certain way. According to Aristotle and many other philosophers，all jokes depend mainly on showing inferiority in another person or group of persons—that is，putting it clearly，on showing that they are worse off than ourselves. Jokes raise our good opinion of ourselves at someone else's expense.

Showing how much better than other people we are is only one reason we like jokes. Someone may also use a joke to express their anger or their cruelty or any other kind of action that is not acceptable to us. We feel free to laugh when we hear about someone sliding on a banana skin. The joke lets us express those attitudes which are usually unacceptable to society. This is probably the reason why some of the jokes，especially those involving cruelty，are so popular with certain people.

    Besides，all jokes depend on our enjoyment of laughing at something that is strange and out of place because it's different from things which are happening around it. The same situation can be either sad or pleasant，depending entirely on how strange and out of place it is. If a girl in a bathing suit falls into a swimming pool，we don't laugh because nothing unusual has happened. But if a man in a smart suit falls in，the situation is at once unusual in a pleasant way and we laugh. A good joke-teller will always try to build up a situation in which one thing is expected until something unexpected suddenly happens，and so we laugh.

Model Railroading

    Would you like to know a fun way to learn about math? Well, you can do that with model railroading. Yes, it's true. You can learn about many school topics without using a school book. Besides that, there are many other benefits that model railroading brings us as well. In this article, we will discuss just a few of those benefits of model railroading.

Patience and problem solving skills

    When you build a model railroad, you have to plan your railroad out. You have to decide where the tracks (轨道) will go, where to put buildings, where to put streets and any other things you would like to add to your model railroad. Also, you have to think about any problems you may have with the design you choose. How will you make railroad crossings? How will you design hills, mountains, and rivers? Deciding on what to do with your model railroad takes a lot of thought and patience, but it is not as difficult as you may think.

Building skills

    With model railroading, you learn how to put together plastic models of buildings. Also, you can learn how to build a table for your design, or make scenery for the geography of your design. Your model railroad runs on electricity, so you learn about electronics as well. These are skills that not only help you build a model railroad; these skills will help you all throughout life.

Fun for family and friends

    Different from many video games, model railroading is a social hobby that lets you communicate with family and friends. This is because you have to communicate with family and friends as you build and run your model railroad. By spending time with the people in your life you love and care about, you learn to become closer and care more for each other. This is one of the best parts of model railroading as a hobby. Of course, the best part about model railroading is running the trains. Watching the trains run around the track and make all the sounds and do all the things that real trains do gives people hours of enjoyment. Also, there is great satisfaction in the fact that you, your family, and your friends built the model railroad.

    I hope you can learn to enjoy model railroading and experience all the benefits you just read about and many others. Happy railroading!

    Although the idea of "zero emission net carbon-positive, sustainable (可持续)" development was promoted worldwide, most cities are at a loss what to do or even some have objected to it. But in Liuzhou, a city in southern China, attitudes could not be more different.

    The Liuzhou Municipality Urban Planning Bureau has signed up Italian architect Stefano Boeri, the father of the forest city movement, to build a self-contained community for up to 30, 000 people. He is the go-to man for such projects thanks to the success of his "vertical forests", two residential (住宅的) towers. Completed in 2014, they remove up to 17.5 tons of soot (煤烟) from the air each year, and a year later one of them was named Best Tall Building Worldwide.

    The Liuzhou project is a much more ambitious undertaking, however. Its homes, hospitals, hotels, schools and offices will be built on a 340-acre site in what Boeri calls the first attempt to create an "urban environment that is really trying to find a balance with nature". Its 100 species of plant life are expected to absorb almost 10, 000 tons of carbon dioxide and 57 tons of pollutants per year, while at the same time producing 900 tons of life-giving oxygen.

    Although the architects haven't published the cost of the forest city, the Milan towers cost only five percent more than traditional skyscrapers.

    The construction of his forest city at Liuzhou is set to begin in 2020, and there is still a great deal of planning and research required before a projected completion date can be set. However, Boeri remains optimistic about the project and has confidence in the soundness of his vision: "I really think that bringing forests into the city is a way to deal with global warming."

    The World's Best Hearing Aid Value Under $200, the Doctor's Choice for Advanced Hearing Aid Technology

    How can a hearing aid cost less than $200?

    When you buy a hearing aid, be sure to choose a pair that every bit of it is as good as one that sells for $2500 or more.

    Although great progress has been made in Advanced Hearing Aid Technology, those cost reductions or falls in prices have not passed on to you­Until Now.

    The MDHearingAid PRO has been carefully tested by leading ENT (Ear, Nose and Throat) physicians and audiologists (听力学家) who have totally agreed that the sound quality and output in many cases is better than more expensive hearing aids.

    Since Medicare and most private insurance do not cover hearing aids, ENT surgeon Dr. Cherukuri designed a game­changing solution without sacrificing the quality of components that you can actually afford.

    "I recommend them to my patients with hearing loss."

—Amy S.Audiologist Indiana

    "I have had this aid two days and all I can say is WOW!"

—Terrsa H.,Grove, NJ

    "It is so much better than the $3000 hearing aid I had been using for years."

—Robert C. South Bend

    The fact is, you don't need to pay high prices for a medical-grade FDA registered hearing aid, MDHearingAid PRO is a high performance hearing aid that works right out of the box with no time-consuming "adjustment" appointments. You can conveniently access a hearing specialist online or by phone­even after the sale. No other company provides such extensive support. Over 75000 satisfied customers agree. Now that you know, why pay more?

    Try it at home within our 45-Day Risk-Free Trail (免费试用).

    If you are not completely satisfied, simply return it within that time period and we will give back your money for a 100% of your purchase price.

    800-475-7618

    Use Code: DB91

    For a year supply of Free Batteries and Free Shipping

    GetMDHearingAid.com

    To have a successful job interview, you need to make good preparations beforehand. Here are some suggestions on what you should do before the interview.

    ⑴Find out as much as you can about the company. What goods or services do they provide? How long has it been founded? Read articles about it. Talk with people who work there. Perhaps you can look at the company website, or find some information on the Internet.

    ⑵Be sure of the time of the interview, the place and the person you'll see.

    ⑶Think about the kind of questions that the employer might ask. Write out questions and possible answers.

    ⑷Rehearse the interview with family members or friends. They can ask you questions from the list you've prepared and you can try to answer.

    ⑸Dress properly. Don't be too formal or too informal. Choose your clothes, shoes.

    ⑹Wash. Make sure that you are clean, and that your teeth have been freshly brushed.