We may think we're a culture that gets rid of our worn technology at the first sight of something shiny and new, but a new study shows that we keep using our old devices (装置)well after they go out of style. That's bad news for the environment—and our wallets—as these outdated devices consume much more energy than the newer ones that do the same things.

    To figure out how much power these devices are using, Callie Babbitt and her colleagues at the Rochester Institute of Technology in New York tracked the environmental costs for each product throughout its life—from when its minerals are mined to when we stop using the device. This method provided a readout for how home energy use has evolved since the early 1990s.Devices were grouped by generation. Desktop computers, basic mobile phones, and box-set TVs defined 1992.Digital cameras arrived on the scene in 1997.And MP3 players, smart phones, and LCD TVs entered homes in 2002, before tablets and e-readers showed up in 2007.

    As we accumulated more devices, however, we didn't throw out our old ones.“The living-room television is replaced and gets planted in the kids' room, and suddenly one day, you have a TV in every room of the house,” said one researcher. The average number of electronic devices rose from four per household in 1992 to 13 in 2007.We're not just keeping these old devices—we continue to use them. According to the analysis of Babbitt's team, old desktop monitors and box TVs with cathode ray tubes are the worst devices with their energy consumption and contribution to greenhouse gas emissions (排放)more than doubling during the 1992 to 2007 window.

    So what's the solution (解决方案)?The team's data only went up to 2007,but the researchers also explored what would happen if consumers replaced old products with new electronics that serve more than one function, such as a tablet for word processing and TV viewing. They found that more on-demand entertainment viewing on tablets instead of TVs and desktop computers could cut energy consumption by 44%.

    Many people spend more than four hours per day on We Chat, and it is redefining the word “friend.” Does friending someone on social media make him or her your friend in real life?

    Robin Dunbar, a professor at Oxford University, found that only 15, of the 150 Facebook friends the average user has, could be counted as actual friends and only five as close friends. We Chat may show a similar pattern.

    Those with whom you attended a course together, applied for the same part-time job, went to a party and intended to cooperate but failed take up most of your WeChat friends. In chat records, the only message may be a system notice, “You have accepted somebody's friend request”. Sometimes when seeing some photos shared on “Moments”, you even need several minutes to think about when you became friends. Also, you may be disturbed by mass messages (群发信息) sent from your unfamiliar “friends”, including requests for voting for their children or friends, links from Pinduoduo.com (a Chinese e-commerce platform that allows users to buy items at lower prices if they purchase in groups) and cookie-cutter (千篇一律的) blessings in holidays.

    You would have thought about deleting this type of “friends” and sort out your connections. But actually you did not do that as you were taught that social networking is valuable to one's success. Besides, it would be really awkward if they found that you have unfriended them already. Then, you keep increasing your “friends” in social media and click “like” on some pictures that you are not really interested. But the fact is that deep emotional connections do not come with the increasing number of your friends in social media.

    If the number of your friends reaches 150, maintaining these relationships can be tough to you, and sometimes even will make you anxious. According to Robin Dunbar, 150 is the limit of the number of people with whom one can maintain stable social relationships.

    In the four months since I last posted articles on my blog, I've been spending a lot of time studying Chinese. I wanted to pass the HSK. From the beginning of my program, the HSK was the end goal of my Chinese learning this year. Luckily, I passed it and now I have one and a half months to go home and stay with my family.

It's really exciting to learn Chinese in an environment where I can study very fast. What's more, I can see my own progress in different ways. When I got here eight and a half months ago, I only knew a few of the 150 words tested in the HSK 1.However, until now, I've taken and passed the 2500­word HSK 5.

    I remember a time around January. I thought my Chinese had reached the point where I was comfortable in my day­to­day conversations. So my progress would slow down greatly. However, it turned out that I was totally wrong. The conversations I can have now far surpass(超过) the ones I was having in January.

    Today I hit a language­learning landmark(里程碑) that was particularly exciting for me: I finished reading Harry Potter and the Sorcerer's Stone in Chinese. It might not seem that exciting, but it was for me because it's the first full book I've read in Chinese. And it's the third language I've read Harry Potter in. I'm especially proud because I spent about seven months reading the first 35 pages, but in the last month and a half, I managed to read about 150 pages. My next challenge is to read a novel written by a Chinese author, rather than one that I've already read many times in English!

    Hopefully, I'll be able to keep up my language­learning progress over the next month and a half, because I know I'll probably never have another opportunity to learn a language like this.

    Do you want to learn a new language？If you do, go to the country where people speak it and learn it from the locals.

Babies made from three people approved in UK

    Babies made from two women and one man have been approved by the UK's fertility regulator. The historic and controversial move is to prevent children from being born with deadly genetic diseases.

    Doctors in Newcastle—who developed the advanced form of In Vitro Fertilization or IVF (人工授精)—are expected to be the first to offer the procedure and have already appealed for donor eggs. The first such child could be born, at the earliest, by the end of 2017.

    Some families have lost multiple children to incurable mitochondrial (线粒体的) diseases, which can leave people with insufficient energy to keep their heart beating.

    The diseases are passed down from only the mother, so a technique using a donor egg as well as the mother's egg and father's sperm has been developed.

    The resulting child has a tiny amount of their DNA from the donor, but the procedure is legal and reviews say it is ethical (伦理的) and scientifically ready.

    "It is a decision of historic importance," said Sally Cheshire, chairwoman of the Human Fertilisation and Embryology Authority (HFEA). "I'm sure patients will be really pleased by what we've decided today."

    But some scientists have questioned the ethics of the technique, saying it could open the door to genetically-modified (转基因) 'designer' babies.

    The HFEA must approve every clinic and every patient before the procedure can take place. Three-person babies have been allowed only in cases where the risk of a child developing mitochondrial disease is very high.

    Prof Mary Herbert, from the Newcastle Fertility Centre, said, "It is enormously pleasing that our many years of research in this area can finally be applied to help families affected by these devastating diseases".

    "Now that we are moving forward towards clinical treatments, we will also need donors to donate eggs for use in treatment to prevent affected women transmitting disease to their children."

    Prof Sir Doug Turnbull, the director of the Welcome Centre for Mitochondrial Research at Newcastle University, said, "We are delighted by today's decision. We will also provide long-term follow up of any children born."

    NHS England has agreed to fund the treatment costs of the first trial of three-person IVF for those women who meet the HFEA criteria, as long as they agree to long-term follow up of their children after they are born.

Round and Round They Go

Space is becoming more crowded. On December 3, a Falcon 9 rocket made by SpaceX thundered into the sky. On board were 64 small satellites, more than any American company had launched before in one go. They have a variety of uses, from space-based- radar to the monitoring of radio-frequency- emissions.

These objects are part of the latest breed of low-Earth-orbit (LEO) satellites. This launch is just taste of what is planned. SpaceX and OneWeb, a communications firm, plan to launch satellites in their thousands, not hundreds. The pair are set to double the total number of satellites in orbit by 2027.

That promises to change things dramatically on Earth. LEO satellites can bring internet connectivity to places where it is still unavailable or unaffordable. This will also be a lasting source of new demand for the space economy. Morgan Stanley, a bank, projects that the space industry will grow from $350 billion in 2016 to more than $1. I trillion by 2040. New internet satellites will account for a half this increase.

For that to happen, however, three worries must be overcome. Debris(碎片)is the most familiar concern. As long ago as 1978, Donald Kessler, a scientist at NASA, proposed situation in which, when enough satellites were packed into low-Earth orbits, any collision could cause a chain reaction which would eventually destroy all space craft in its orbital plane(平面). The syndrome which bears Mr. Kessler's name weighs heavily on the minds of executives at the new satellite firms. Debris could cause entire tracts(广阔的一片) of space to be unusable for decades.

Solutions exist. One is to grab malfunction satellites and pull them down into Earth's atmosphere. Another is to monitor space more intensively for debris; a US Air Force programme called Space Fence is due to start in 2019. But technology is only part of the answer. Rules are needed to govern the safe disposal(清除) of old satellites from low-Earth orbit. The United States' Federal Communications Commission is revising its regulations with this in mind. Other countries should follow suit.

Cyber-security is a second, long-standing worry. Hackers could take control of a satellite and seal intellectual property, redirect data flows or cause a collision. The satellite industry has been slow to respond to such concerns. But as more of the world's population comes to rely on the infrastructure of space for access to the internet, the need for action intensifies.

The third issue follows from the first two. If a simple mistake or a cyber-attack can cause a chain reaction which wipes out hundreds of billions of dollars of investment, who is liable? Underwriters(保险商) are studying the plans of firms that wish to operate large numbers of satellites. But there is a long way to go before the risks are well understood, let alone priced.

As space becomes more commercialized mind-bending prospects open up: packages moved across the planet in minutes by rocket rather than by plane, equipment sent to other small planets, passengers launched into orbit and beyond. All that and more may come, one day. But such activities would raise the same questions as LEO satellites do. They must be answered before the space economy can truly develop.

A team of biologists (生物学家) recently studied wildlife in the forests of northern Ecuador. While doing so, they made a surprising discovery: a Mindo harlequin toad (明多斑足蟾). The creature hadn't been seen alive in 30 years. The scientists couldn't believe their eyes. "It took our brains a while to believe it was a Mindo harlequin toad," says Melissa Costales, a conservation biologist from University of New Brunswick.

The Mindo harlequin is the latest harlequin toad species "to come back from the dead," says Costales. Since 2003, eight others have been found, three of them in Ecuador.

Until recently, 13 of the 25 species of harlequin toads in Ecuador had gone unseen since the 1980s or early 1990s. Scientists thought most of them had been killed by a disease called chytrid (壶菌). This illness is especially harmful to the harlequin toad.

Costales says the Mindo harlequin toad may have developed a resistance (抵抗力) to the disease. That would explain the toad's reappearance. And it could spell good news for other harlequins. Since discovering the first one, Costales's team has found five more. They were all tested for chytrid. None had the disease. But that doesn't mean the survival of the species is guaranteed (保证), Costales says. The harlequin toad is still endangered.

Costales is developing a conservation plan with a zoology museum in Ecuador. She wants to make sure the Mindo harlequin toad doesn't fall back into extinction. "Each rediscovery gives us a second chance to develop better conservation plans," she says. "Not every day do we have the chance to rediscover a species that we believed to be extinct."