Energy independence. It has a nice ring to it. Doesn't it? If you think so, you're not alone, because energy independence has been the dream of American president for decades, and never more so than in the past few years, when the most recent oil price shock has been partly responsible for kicking off the great recession.

    “Energy independence” and its rhetorical (修辞的) companion “energy security” are, however, slippery concepts that are rarely though through. What is it we want independence from, exactly?

    Most people would probably say that they want to be independent from imported oil. But there are reasons that we buy all that oil from elsewhere.

    The first reason is that we need it to keep our economy running. Yes, there is a trickle（涓涓细流）of biofuel available, and more may become available, but most biofuels cause economic waste and environmental destruction.

    Second, Americans have basically decided that they don't really want to produce all their own oil. They value the environmental quality they preserve over their oil imports from abroad. Vast areas of the United States are off-limits(禁止) to oil exploration and production in the name of environmental protection. To what extent are Americans really willing to endure the environmental impacts of domestic energy production in order to cut back imports?

    Third, there are benefits to trade. It allows for economic efficiency, and when we buy things from places that have lower production costs than we do, we benefit. And although you don't read about this much, the United States is also a large exporter of oil products, selling about 2 million barrels of petroleum products per day to about 90 countries.

    There is no question that the United States imports a great deal of energy and, in fact, relies on that steady flow to maintain its economy. When that flow is interrupted, we feel the pain in short supplies and higher prices, At the same time, we derive(得到，获得) massive economic benefits when we buy the most affordable energy on the world market and when we engage in energy trade around the world.

    Rainforests, it turns out, are not created equal. Take the Amazon rainforest, an area that covers about 7 million square kilometers. But within that huge expanse are all kinds of ecological zones, and some of these zones, says Greg Asner, are a lot more crowded than others.

    “Some forests have many species of trees,” he said, “others have few. Many forests are unique from others in terms of their overall species composition…” And all of these different small areas of forest exist within the giant space that is the Amazon Rainforest.

    So Asner, using the signature technique called airborne laser-guided imaging spectroscopy, began to map these different zones from the air. “By mapping the traits of tropical forests from above,” he explains, “we are, for the first time, able to understand how forest composition varies geographically.”

    The results show up in multicolored maps, with each color representing different kinds of species, different kinds of trees, the different kinds of chemical they are producing and using, and even the amount of biodiversity, the animal and plant species that live within each zone.

    Armed with this information, Asner says decision-makers now have “a first-time way to decide whether any given forest geography is protected well enough or not. If not, then new protections can be put in place to save a given forest from destruction.”

    Asner says the information is a great way for decision-makers to develop a “cost-benefit ratio type analysis.”  Conservation efforts can be expensive, so armed with this information, government leaders can ensure they are making the most of their conservation dollars by focusing on areas that are the most biologically diverse or unique.

    The next step, Asner says, is to take his project global, and to put his eyes even higher in the sky, on orbital satellites. “The technique we developed and applied to map Peru is ready to go global.” Asner said. “We want to put the required instrumentation on an Earth-orbiting satellite, to map the planet every month, which will give the best possible view of how the world's biodiversity is changing, and where to put much needed protections.

    A fourth-grade teacher allowed one of her students to shave her head in the schoolyard, after bullies（仗势欺人者）teased him about his own short buzz cut（短寸头发型）. Tori Nelson got the idea after noticing that Matthew Finney, a shy boy from her homeroom at Winlock Miller Elementary School in Washington state, was standing outside his classroom crying and wearing a winter hat.

    Ms. Nelson could see the back of his neck had been shaved, and since Matthew usually had very thick brown curly hair, she realized that he'd had a haircut over the weekend. She asked him what was wrong, and he said he'd gotten a buzz cut for the summer. But this morning, a fifth grader on the bus made fun of him, and he didn't want to come to class and get teased by other kids. Ms Nelson tried to convince Matthew to come inside, but since school rules prohibit kids from wearing hats indoors he refused – explaining that he was afraid of showing his haircut to the other children in case they also made fun of him.

    Finally I said: "If you take off your hat and come to class, I'll let you give me a buzz cut, too," 'Ms Nelson told Yahoo Parenting. I figured it's just hair, and mine is already short anyway. I might as well get it shorter in time for the warm weather.'

    Matthew excitedly took her up on the offer, and Ms Nelson and another teacher gathered all the fourth graders together during break time. A school employee brought in scissors, which Matthew used to the cheers of his classmates, excitedly watching as his teacher's hair fell away onto the ground in the schoolyard.

    'It was a lot of fun for the kids, and it helped Matthew feel better about himself,' said Ms Nelson.' You have to do what it takes to reach children. Teaching isn't just about reading and writing, it's about self-esteem and accepting differences.'

    The month of March was a milestone for supporters of renewable energy in the U.S. For the first time, wind and solar power accounted for more than 10% of the country's electricity—up from less than 1% at the turn of the century. And total wind and solar power-plant capacity(发电量) is expected to grow more than 30% over the course of this year and next, according to the Energy Information Administration.

    Such forecasts have led many scientists and policymakers to think that moving a large part of the nation's power supply to renewable sources—as cities from Miami Beach to Salt Lake City have promised to do—may not be as far-fetched as once thought. But like any debate, there are dissenters, including those inside the federal government. Their argument is that the nation demands an uninterrupted supply of electricity and cannot count on sun, wind and natural gas to provide it. “You need solid hydrocarbons(固体碳氢化合物) on-site for rising peak demand,” Environmental Protection Agency administrator Scott Pruitt said on Fox Business in May, referring to the importance of coal as a power source.

    Many experts say the government's concern fails to account for how the power grid(电网) has improved in recent decades. Utility companies(公共事业公司) have developed innovative ways to move electricity from place to place to account for variation in weather. Battery technology can store power for use when renewable sources cannot operate, meaning solar power can be used on days when the sun doesn't shine. And the nation's vast supply of natural gas can be turned into usable energy with the flick of a switch.

    “I don't think 5 or 10 years ago I'd be comfortable telling you we could not sacrifice reliability when we're going to have 35% of our energy come from wind,” said Ben Fowke, CEO of the utility company Xcel Energy, at a recent conference. “I'm telling you, I'm very comfortable with that today.”

    Indeed, many parts of the country are already close to that reality. In some regions, like Iowa and Kansas, renewable energy supplies more than 25% of the electricity. The market has shifted so far in favor of natural gas and renewable energy that even the most concerted federal effort is unlikely to stop its growth. Any attempt to slow the growth of wind and solar will face strong pushback. “If anyone wants to do away with it,” Republican Senator Chuck Grassley told Yahoo News of the federal government's potential cuts to wind energy, “he'll do it over my dead body.”

    But the federal government could slow the acceleration—and with billions of dollars in private and public investments at risk, the pace of change matters. Decisions made today will shape the future of the nation's energy grid for decades to come.

    Angel Garcia Crespo is a computer engineer at Carlos III University of Madrid in Spain. His group has invented a new way for deaf-blind people to “watch” TV. The idea for the technology grew out of previous work by his group. The team had already worked on making audiovisual(视听的) materials accessible to people with either vision or hearing disabilities. But the group wanted to help people with both challenges. So they asked some deaf-blind people what would help.

    In addition to relying on their sense of touch to communicate, deaf-blind people can also get and send information with a Braille line. The Braille system uses patterns of raised dots to stand for letters and numbers. A Braille line is an electronic machine with a changeable Braille display. Dots rise up or drop down based on the information sent to the machine.

    Now the new system changes TV signals to data a Braille line can use. “The key to the system is the possibility of using subtitles(字幕) to collect TV information, " Garcia Crespo explains. "Subtitles travel with the image(影像) and the audio in electromagnetic waves we don't see. But an electronic system can keep those waves."

    First, a computer program, or app, pulls out the subtitles and visual descriptions from the broadcast signal. The system then combines the information and changes both into data for Braille.

    Now another app gets to work, which sends the data out to people's Braille lines on demand. “This is done in real time, in less than a second, " Garcia Crespo says. This lets a deaf-blind person "watch" TV as it's broadcast. The system will work with various Braille lines, as long as there's a bluetooth connection available. Now, the system is only used in Europe, and it should soon be available in the US.

    Recently, some Chinese experts advise people to be more careful about making a "V" gesture (手势) while taking a photo, because the fingerprints may be stolen.

    It is possible. If the distance between the person and a smartphone is less than half a meter, the possibility of the fingerprint being stolen will be bigger. Having fingerprints stolen can cause a lot of difficulty, as they are used in many things, including ID cards, passports and online payments. So it's a must to pay attention to their protection and avoid them being spread on the Internet.

    This kind of discussion was first raised by a Japanese research center, the National Institute of Informatics.

    ZengQiaoyi, 19, who likes sharing selfies (自拍) on WeChat, said she is also worried about it. She said she seldom posts pictures with "V" gestures and most pictures she shares are made to be not so clear by certain software. "I blur backgrounds in selfies, hoping to hide my location," she added.

    Tan Tieniu, a scientist, said at the 2016 China National Computer Congress that using fingerprints instead of passwords or voice identification is far from safe, compared with face recognition (辨认).

    But a police officer from Jiangsu province, said locals don't need to be overly anxious, because the cameras of many cellphones are not clear enough, and the shooting distance of most photos taken by cameras is too far.