America is a mobile society. Friendships between Americans can be close and real, yet disappear soon if situations change. Neither side feels hurt by this. Both may exchange Christmas greetings for a year or two, perhaps a few letters for a while—then no more. If the same two people meet again by chance, even years later, they pick up the friendship. This can be quite difficult for us Chinese to understand, because friendships between us flower more slowly but then may become lifelong feelings, extending (延伸) sometimes deeply into both families.

    Americans are ready to receive us foreigners at their homes, share their holidays, and their home life. They will enjoy welcoming us and be pleased if we accept their hospitality (好客) easily, but truly can't manage the time to do a great deal with a visitor outside their daily routine. They will probably expect us to get ourselves from the airport to our own hotel by bus. And they expect that we will phone them from there. Once we arrive at their homes, the welcome will be full, warm and real. We will find ourselves treated hospitably.

    Another difficult point for us Chinese to understand Americans is that although they include us warmly in their personal everyday lives, they don't show their politeness to us if it requires a great deal of time. This is usually the opposite of the practice in our country where we may be generous with our time. Sometimes, we, as hosts, will appear at airports even in the middle of the night to meet a friend. We may take days off to act as guides to our foreign friends. The Americans, however, express their welcome usually at homes,

    For the Americans, it is often considered more friendly to invite a friend to their homes than to go to restaurants, except for pure business matters. So accept their hospitality at home!

    When your pen is broken, the batteries (电池) in your toys run out, or you have some leftover food, what will you do with these things? You will probably throw them all into one bin. But actually, all of these pieces of rubbish need to be sorted (分类) separately.

    Rubbish sorting is a big problem worldwide. In recent years, some Chinese cities have been working hard on it. Shanghai has worked with Alipay to create a "green account (账户)" service. Account owners get points by correctly sorting their rubbish. Through the Alipay app, they can exchange the points for milk, phone cards or other products. The city is asking all people living there to sort their rubbish into four groups: wet, recyclable, harmful and dry.

    Wet waste is something you don't want but that pigs can eat. Plastics, glass, paper and other things that can be reused are recyclable waste. Harmful waste includes things like medicine, batteries and bulbs. Finally, any waste that's not wet, recyclable or harmful will go in the "dry waste" bin.

    Many other Chinese cities are also sorting their rubbish in this way. For example, Shenzhen has been doing this since 2012. Students there also receive waste-sorting guidebooks that they must study.

    In fact, there are still many workers specially working for sorting rubbish by hand in China. There is still a long way to go. But it's never too late for every Chinese to learn how to sort rubbish properly and protect the environment.

    If you don't sort your rubbish, all of it will go to a landfill (垃圾填埋场) and be buried together.

    These landfills can take up much ground that could be used for planting. The electronic waste you throw away, such as batteries or used mobile phones, can cause pollution. Other pieces of rubbish, like the metal part of a pen, can be used to make other things if they are properly recycled.

    Attitudes toward new technologies often fall along generational lines. That is, generally, younger people tend to outnumber older people on the front end of a technological change. It is not always the case, though. When you look at attitudes toward driverless cars, there doesn't seem to be a clear generational divide. The public overall is split on whether they'd like to use a driverless car. In a study last year, of all people surveyed, 48 percent said they wanted to ride in one, while 50 percent did not.

    The fact that attitudes toward self-driving cars appear to be so steady across generations suggests how transformative the change to driverless cars could be. Not everyone wants a driverless car now-and no one can get one yet—but among those who are open to them, every age group is similarly involved.

    Actually, this isn't surprising. Whereas older generations are sometimes reluctant to adopt new technologies, driverless cars promise real value to these age groups in particular. Older adults, especially those with limited mobility or difficulty driving on their own are one of the classic use-cases for driverless cars.

    This is especially interesting when you consider that younger people are generally more interested in travel-related technologies than older ones.

    When it comes to driverless cars, differences in attitude are more pronounced based on factors not related to age. College graduates, for example, are particularly interested in driverless cars compared with those who have less education: 59 percent of college graduates said they would like to use a driverless car compared with 38 percent of those with a high-school diploma or less.

    Where a person lives matters, too. More people who lived in cities and suburbs said they wanted to try driverless cars than those who lived in rural areas.

    While there's reason to believe that interest in self-driving cars is going up across the board, a person's age will have little to do with how self-driving cars can become mainstream. Once driverless cars are actually available for sale, the early adopters will be the people who can afford to buy them.

    Scientists at the University of Oxford have developed new artificial intelligence(AI) software to recognize and follow up the faces of chimpanzees(黑猩猩)in the wild. The new software will allow researchers and wildlife conservationists to significantly cut back on time spent analyzing videos, according to the new paper published in Science Advances.

    For species(物种)like chimpanzees which have complex social lives and live for many years, getting photos of their behavior taken from short-term field research can only tell us so much," says Dan Schofield, researcher and DPhil student at Oxford University's Private Models Lab, School of Anthropology. "By taking advantage of the power of machine learning to unlock large video files, it makes it possible to measure behavior over the long term."

    The computer model was trained using over 10 million images(影像):from Kyoto University s Primate Research Institute(PRI) video files of wild chimpanzees in Guinea, West Africa. The new software is the first to continuously track and recognize individual a wide range of poses, performing with high accuracy in difficult conditions such as low lighting and poor image quality.

    "Access to this large video file has allowed us to use deep neural networks to train models to a degree that was previously not possible," says Arsha Nagrad, co-auther of the study and DPhil student at the Department of Engineer Science, University of Oxford." Additionally, our new software differs from previous primate face recognition software in that it can be applied to videos with limited manual intervention(人工干预), saving hours of time."

    The technology can be potentially used to monitor species for conservation Although the present application focuses on chimpanzees, the AI software provided will be applied to other species, and help drive the adoption of AI systems to solve(解决)a range of problems in the wildlife sciences.

According to a study published this week, habitual napping (打盹) appears to be associated with a large brain volume in adults although experts stressed that further research was needed. It reduces the cost caused from the lost time and the fatigue-related errors. The work followed previous studies that suggested a brief doze could improve people's ability to learn.

Arianna Huffington, a co-founder of Huff Post and the founder and chief executive of Thrive Global, said, "Given the latest science on the effectiveness of napping and the clear link between employees feeling well rested and their productivity, it's long past time that businesses embrace short naps at work."

Some businesses, including Thrive Global, have already introduced facilities for employees to take naps. Google introduced sleep pods as far back as 2014 and companies like Nike and Ben & Jerry's introduced nap rooms. The practice has even been adopted by the NHS, with a growing number of hospitals introducing sleep pods for staff in an effort to help them get more rest. Employees, it seems, are enthusiastic. Sean Greenwood, of Ben & Jerry's, said, "If a quick nap gets employees more involved and creative, we're happy to provide that for our team members."

Unfortunately, the practice of napping still suffers from our collective concept that sleep equals weakness and laziness. However, the performance-enhancing benefits of naps have been no secret to many leaders throughout history. It also gives the higher-ups the chance to acknowledge the 24/7 culture and come up with top-down solutions that encourage workers to take care of themselves in and out of work.

While sleep experts stressed that a daytime doze could be beneficial, they said it was crucial to get enough shut-eye at the end of a day. It is the late stage of sleep, sometimes missed by early risers, that strengthens the nerve circuits that make for learning and memory, allowing the brain to make and consolidate new neutral connections. Additionally, prioritizing sufficient sleep during the regular nightly sleep period is essential for overall well-being.

Online classes began to be popularized just a few decades ago. They are advertised as a way for adults to finish their education and students to learn the material at their own pace—it is far more suitable for people with busy schedules.

But after being enrolled in an online course last fall semester, I came to realize online classes were merely a means to fulfil course requirements.

First of all, students lack the desire to learn, and they simply complete their assignments to receive credit for a passing grade rather than genuinely engage with the course material.

As online courses tend to have more than 100 students, most of the assignments are short and simple. They are not designed for students to interact with the material in depth but designed to be graded casily to accommodate such a large number of students.

Perhaps the biggest disadvantage of taking an online class is the absence of face-to-face interaction between the teacher and their students. Live sessions are infrequent and are often scheduled during the middle of the day when students have to attend other classes or work. The office hours of the professor may also be during inconvenient times for many students as well. Most interaction with the professor has to be through email which is often impersonal. It is nearly impossible for students to build a relationship with their professor.

There is also little interaction amongst students. It can be harder for students to create study groups and form relationships with their peers.

Online classes also require either a computer or laptop and a reliable internet connection. Not all students have access to these types of resources, whether it is for financial or other reasons, and some students can be put at a disadvantage.

Offering online classes certainly helps students who would otherwise not be able to attend classroom sessions. However, they fail to provide a genuine education with an emphasis on convenience rather than critical thinking. We need restructured online classes in which students can have a learning experience that will actually provide quality education.