How fit are your teeth? Are you lazy about brushing them? Never fear: An inventor is on the case. An electric toothbrush senses how long and how well you brush, and it lets you track your performance on your phone.

    The Kolibree toothbrush was exhibited at the International Consumer Electronics Show in Las Vegas this week. It senses how it is moved and can send the information to an Android phone or iPhone via a Bluetooth wireless connection.

    The toothbrush will be able to teach you to brush right (don't forget the insides of the teeth!) and make sure you're brushing long enough. “It's kind of like having a doctor actually watch your brushing on a day-to-day basis,” says Thomas Serval, the French inventor.

    The toothbrush will also be able to talk to other applications(应用) on your phone, so developers could, for example, create a game controlled by your toothbrush. You could score points for beating monsters(怪物) among your teeth. “We try to make it smart but also fun,” Serval says.

    Serval says he was inspired by his experience as a father. He would come home from work and ask his kids if they had brushed their teeth. They said “yes,” but Serval would find their toothbrush heads dry. He decided he needed a brush that really told him how well his children brushed.

    The company says the Kolibree will go on sale this summer, for $99 to $199, depending on features. The U.S. is the first target market.

    Serval says that one day, it'll be possible to replace the brush on the handle with a brushing unit that also has a camera. The camera can even examine holes in your teeth while you brush.

    Almost every machine with moving parts has wheels, yet no one knows exactly when the first wheel was invented or what it was used for. We do know, however, that they existed over 5,500 years ago in ancient Asia.

    The oldest known transport wheel was discovered in 2002 in Slovenia. It is over 5,100 years old. Evidence suggests that wheels for transport didn't become popular for a while, though. This could be because animals did a perfectly good job of carrying farming tools and humans around.

    But it could also be because of a difficult situation. While wheels need to roll on smooth surfaces, roads with smooth surfaces weren't going to be constructed until there was plenty of demand for them. Eventually, road surfaces did become smoother, but this difficult situation appeared again a few centuries later. There had been no important changes in wheel and vehicle design before the arrival of modem road design.

    In the mid-1700s, a Frenchman came up with a new design of road—a base layer (层) of large stones covered with a thin layer of smaller stones. A Scotsman improved on this design in the 1820s and a strong, lasting road surface became a reality. At around the same lime, metal hubs (the central part of a wheel) came into being, followed by the pneumatic tyre(充气轮胎) in 1846. Alloy wheels were invented in 1967, sixty years after the appearance of tarmacked roads (柏油路). As wheel design took off, vehicles got faster and faster.

    Have you ever lost your direction? Then you might find satellite navigation(satnav) systems(卫星定位系统) helpful.

    A satnav system uses groups of satellites. They send information to a receiver(接收器), such as your smartphone. Then they can find where you are.

The earliest satnav system is the Global Positioning System(GPS) of the United States. The US has put 24 satellites into space to make sure GPS can locate(定位) a person correctly and globally. Likewise, Russia's GLONASS and European Union's Galileo can also work globally.

    But China is catching up, building its own BeiDou Navigation Satellite System. BeiDou is China's homegrown satnav system, reported Xinhua. It was set up in 2000, when China sent BeiDou's first navigation experiment satellite into space. With it, China became the third country to build a satnav system after the US and Russia.

    BeiDou can find you wherever you are. It helps you go faster by finding shortcuts(捷径) and using correct directions. When you are in trouble and call the police, they will know exactly where you are if you have a cellphone that uses BeiDou.

    Today, there are more than 20 BeiDou satellites above our heads. And the system is able to offer open services to the Asia-Pacific region(亚太地区).

    In November, China plans to send more BeiDou-3 satellites into space. BeiDou-3's position accuracy(准确度) is less than five meters, Ran Chengqi, a senior designer of the satellite navigation system, told China Daily.

    By 2020, BeiDou is planned to have 35 satellites and begin serving globally, reported Xinhua.

    Many leading AI researchers think that in a matter of decades, artificial intelligence will be able to do not merely some of our jobs, but all of our jobs, forever transforming life on Earth.

    The reason why many reject this as science fiction is that we've traditionally thought of intelligence as something mysterious that can only exist in biological organisms, especially humans. But such an idea is unscientific.

    From my point of view as a physicist and AI researcher, intelligence is simply a certain kind of information-processing performed by elementary particles(基本粒子) moving around, and there is no law of physics that says one can't build machines more intelligent than us in all ways. This suggests that we've only seen the tip of the intelligence iceberg and that there is an amazing potential to unlock the full intelligence that is potential in nature and use it to help humanity.

    If we get it right, the upside is huge. Since everything we love about civilization is the product of intelligence, amplifying (扩大) our own intelligence with AI has the potential to solve tomorrow's toughest problems. For example, why risk our loved ones dying in traffic accidents that self-driving cars could prevent or dying of cancers that AI might help us find cures for? Why not increase productivity through automation (自动化) and use AI to accelerate our research and development of affordable sustainable (可持续的) energy?

    I'm optimistic that we can develop rapidly with advanced AI as long as we win the race between the growing power of our technology and the knowledge with which we manage it. But this requires giving up our outdated concept of learning form mistakes. That helped us win the race with less powerful technology: We messed up with fire and then invented fire extinguishers (灭火器), and we messed up with cars and then invented seat belts. However, it's an awful idea for more powerful technologies, such as nuclear weapons or superintelligent AI— where even a single mistake is unacceptable and we need to get things right the first time.

How Room Designs Affect Our Work and Feelings

    Architects have long had the feeling that the places we live in can affect our thoughts, feelings and behaviors. But now scientists are giving this feeling an empirical（经验的，实证的） basis. They are discovering how to design spaces that promote creativity, keep people focused and lead to relaxation.

    Researches show that aspects of the physical environment can influence creativity. In 2007, Joan Meyers-Levy at the University of Minnesota, reported that the height of a room's ceiling affects how people think. Her research indicates that higher ceilings encourage people to think more freely, which may lead them to make more abstract connections. Low ceilings, on the other hand, may inspire a more detailed outlook.

    In additions to ceiling height, the view afforded by a building may influence an occupant's ability to concentrate. Nancy Wells and her colleagues at Cornell University found in their study that kids who experienced the greatest increase in greenness as a result of a family move made the most gains on a standard test of attention.

    Using nature to improve focus of attention ought to pay off  academically, and it seems to, according to a study led by C. Kenneth Tanner, head of the School Design & Planning Laboratory at the University of Georgia. Tanner and his team found that students in classrooms with unblocked views of at least 50 feet outside the window had higher scores on tests of vocabulary, language arts and maths than did students whose classrooms primarily overlooked roads and parking lots.

    Recent study on room lighting design suggests than dim（暗淡的） light helps people to loosen up. If that is true generally, keeping the light low during dinner or at parties could increase relaxation. Researchers of Harvard Medical School also discovered that furniture with rounded edges could help visitors relax.

    So far scientists have focused mainly on public buildings. "We have a very limited number of studies, so we're almost looking at the problem through a straw（吸管）," architect David Allison says. "How do you take answers to very specific questions and make broad, generalized use of them? That's what we're all struggling with."

How to make the most of your time with your host family

Living and studying abroad can be a meaningful and enriching experience. And living with a host family is one of the best ways to immerse (沉浸) yourself in the culture. {#blank#}1{#/blank#}Here are some tips on making the most of your time with your host family.

{#blank#}2{#/blank#}You have to understand that host families are doing it just because they want to give a kid the opportunity to live abroad. They are willingly changing their lives so you can experience this! With their support, things become easier.

Many people struggle to feel comfortable with their host families at first. This is a completely normal feeling! You've just left everything you've known for years behind to start a new life. It's okay to be confused. {#blank#}3{#/blank#}While you may know the language, some expressions can be hard to understand at first. Be patient with yourself and remember that you will adapt but it will take some time.

Feeling at home can be difficult at the beginning. That's why spending time in common areas is necessary. If you spend all your time in your room, it's going to be hard to feel like you belong. Joining in everyday activities with your host family will help you create a family bond. For example, some families like having dinner together on weekends. Make time for those moments.{#blank#}4{#/blank#}

Communication is key. If you are unsure about something, ask! It's normal to know few customs and habits at first, so instead of doing things blindly, just ask. Your host family will understand and help you. {#blank#}5{#/blank#}When you are out with your host family, ask them about these, and keep learning them when you are on your own!

A. The language barrier can also be a struggle.

B. Showing gratitude will take you a long way.

C. Keep in mind that when in Rome, do as the Romans do.

D. Then, you'll have chances to expose yourself to their language.

E. It's also normal not to know a lot about unspoken social rules of the country.

F. Not only will they appreciate it but you will also feel like a part of their world.

G. However, living with a foreign family can be difficult and adapting to it can take some effort.