We brush our teeth daily, but do you know everything you need to know about dental care and hygiene? Believe it or not, there is a lot more than most people realize. Luckily, here are several apps that can help you.

●Brush DJ

    You should brush your teeth for full two minutes as recommended by dentists, but that time can be difficult to judge. Many recommend you listen to music, because many songs are just around two minutes in length. Brush DJ has loads of great tunes that will get you into the two­minute habit. There are both songs to listen to, and videos to watch, and you'll find a variety of awesome tunes.

●Orasphere

    It's recommended that Orasphere videos be used by dentists for their patients, so they can learn about procedures. Those who do use these videos say that the software can greatly decrease the amount of time it takes to explain procedures to patients.

●American Dental Association(ADA)

    Everything you ever wanted to know about your teeth, and then some, can be found on the American Dental Association(ADA) website. You'll find loads of great articles that have the latest news about dentistry（牙科）. Those interested in dental careers will find plenty of information to head them in the right direction, and there's even a section devoted to public dental programs, including Give Kids a Smile and Fluoride in Water.

●DDS GP

    Here is more presentation software that explains all types of dental procedures. This is helpful for dentists to have, because they can better explain procedures to their patients.

●Dentistry IQ

    You can find information for dentists, hygienists, assistants, office managers, and more at Dentistry IQ. You can also get information about new products, clinical practices, and much more. In addition, you can learn about career opportunities, the most recent practices, and a whole lot more.

    Two thieves came to a house to steal something, they dug a hole in the wall of the house.

    There lived many mice in the house. The woman in the moonlight saw a mouse crawl (爬行) into the house. “Look! In comes one,” she said to the man in the house. He was so frightened that he hurriedly crawled out of the house and said to the one waiting outside, “She found me when I was just in.” But the thief outside didn't believe him, so he said, “Let us two try to crawl into the house together.” At that time two mice happened to crawl into the house, too. The woman saw the mice and shouted, “In come two, catch them!” The two thieves were terribly frightened. The man in the house said, “You saw them come in but where are they? I will catch them tonight.” The two thieves started running away at once.

    The two thieves wanted to make it clear whether they had been found or not the night before. The next day they acted as men selling sweet potatoes and came before the house. The man and the woman were ploughing in their fields. The rein (缰绳) broke and the woman came home for a rope. She saw two men selling sweet potatoes and wanted to buy some. She picked out two which looked like mice. At the time the man couldn't wait for her any longer in the fields and he ran back from the fields to hurry her up. The woman showed the sweet potatoes to the man and said, “How they look like the two of last night.” The man said, “I asked you to fetch a rope, why don't you hurry for it?” The two thieves ran away very quickly without their sweet potatoes.

    Contrary to popular belief, people who sleep six to seven hours a night live longer, and those who sleep eight hours or more die younger, according to the latest study ever conducted on the subject. The study, which has tracked the sleeping habits of 1.1 million Americans for six years, weakens the advice of many sleep doctors who have long recommended that people get eight or nine hours of sleep every night.

    “There's an old idea that people should sleep eight hours a night, which has no more scientific basis than the gold at the end of the rainbow,” said Daniel Kripke, professor of psychiatry（精神病学）at the University of California at San Diego who led the study published in a recent copy of JAMA Psychiatry.

    The study was not designed to answer why sleeping longer may be harmful or whether people could extend their lifespan by sleeping less.

    But Kripke said it was possible that people who slept longer tended to suffer from short-term absence of sleeping, a condition where weak breathing puts stress on the heart and brain. He also stressed that the need for sleep was similar to that for food, where getting less than people want may be better for them.

    The study quickly caused warnings and criticism（批评）, with some sleep experts saying that the main problem of America's sleep habits was deprivation（剥夺）, not sleeping too much.

    “None of this says sleep kills people,” said Daniel Buysse, a psychiatrist at the university of Pittsburgh Medical Center.

    “You should sleep as much as you need to feel awake, alert and attentive the next day,” Buysse added. “I'm much more concerned about people short-changing themselves on sleep than people sleeping too long.”

    “Sleeplessness produces a variety of health consequences that were not measured in the study,” critics said.

    Scientists are studying different foods, and they will see which foods protect us from cancer(癌症), and which cause it. It is known that a healthy diet(饮食) will help keep a healthy body weight, which can also decrease the risk(风险) of many types of cancer.

    Fruit and vegetables

    Fruit and vegetables are an important part of a healthy diet. They can decrease the risk of some cancer types like mouth and throat cancer. They are a good source of many important nutrients such as vitamin A, vitamin C, vitamin E, and are an excellent source of fiber.

    Our advice

    Try to get plenty of fruit and vegetables in your diet. Eating fruit and vegetables with a variety of colors will help you get many kinds of vitamins and minerals, as the chemicals that give these foods their colors are good for you.

    Meat

    Eating lots of red and processed meat can increase(增加) your risk of stomach cancer. Red meat includes all fresh and frozen beef, pork and lamb. Processed meat includes ham, bacon and sausage. White meat, such as chicken, is unlikely to increase your risk of cancer.

    Our advice

    Eat smaller and fewer parts of red and processed meat. Try using beans or peas instead of meat in your diet. When you cook meat, use low-temperature methods.

    Fat

    Fat is a necessary part of our diet but high-fat diet can increase our risk of cancer, heart disease and other diseases. Meat is higher in saturated fat(饱和脂肪) and eating too much saturated fat may increase your risk of breast cancer.

    Our advice

    Try not to eat too much fatty foods. In particular, try to cut down on saturated fat contained in fatty meat, biscuits, and butter. Try to avoid frying foods in lots of oil.

    Studying the DNA of 300 mice has flagged up genes which have been linked to hereditary (遗传的) sight loss for the first time. Researchers say because mice's genes are so similar to humans', their findings could lead to the treatment of more genetic diseases.

    Scientists at the University of California, Davis studied information from a data bank of mice's genetic material. They found 347 genes linked to eye problems, with just 86 of them having been studied in the past.

    Only around 50 to 75 percent of hereditary eye diseases in human can be explained with present science. The researchers believe these hundreds of new genes found in mice could be a key to explaining-and therefore being able to treat the other 25-50 percent.

    "This is extremely valuable for people with hereditary eye disease," said researcher Professor Ala Moshiri. "All researchers are going to start using these data. In the past, we knew the problem was there but we didn't know where to look. Now eye centers can call back patients and screen them for these new genes. We expected that more and more of these genetic diseases will be treatable." Also, the fact is that more than 60 percent of eye problems at birth are ones resulting from the baby's parents!

    Thanks to data from the International Mouse Phenotyping Consortium (IMPC), which is trying to work out what every single gene in a mouse is responsible for, with the aim of translating it to humans, scientists are moving closer to figuring out all genetic causes of blindness. To do this, scientists separate a single gene from other ones at a time and then observe what effect it has on the mouse for a long time. This has so far been done more than 7,000 times and has achieved great success. Researchers are now working alongside eye care centers in Texas and Iowa in order to compare the mice's genes to those of patients.

    Volunteering abroad is a great way to help others, improve your skills and become a more confident, independent person. If you are interested in volunteering abroad, here are some places to go.

    Australia

    If you seek a life on the beach, in a great climate with friendly people, Australia might be your best bet. With thousands of volunteers already signing up to leave for Australia during the holidays, it will be a very popular option.

    Brazil

    This vast country has some great opportunities on offer and is especially popular this year. A lot of volunteer work is available in Brazil centers on conservation and ecological projects. With the world's largest rainforest in Brazil, of which huge part is in danger, there are lots of different jobs you can do.

    Kenya

    Kenya is the destination for those seeking an African experience. Generally volunteers in Kenya work in orphanages (孤儿院) or with local children living in slums (贫民窟). There is a great demand for volunteers in Africa because many people live in poverty, so if you truly feel like making a difference to a community, Kenya should be at the top of your list.

    Costa Rica

    Golden sandy beaches, clear coastlines and beautiful cities are what Costa Rica is all about. Because of its small size, you can see a lot of the country in just a short time. You can really make the most of your time as a volunteer. A lot of work is needed with wildlife and ecological work, so if you want to look after turtles (海龟) on the beach, Costa Rica could be just the place for you.