Blind people usually possess one advantage over other people who can see. Their sense of hearing is far more acute. Bats, whose sight is poor, use a sound location system to help them avoid blocks in the dark. They send out pulses of sound waves, pitched at 50,000 cycles per second, far above the limits of the human ear, which can hear sounds up to frequencies of about 20,000 cycles per second. As the echoes bounce back off obstacles such as trees and walls, the bats are able to take proper action.

    The first steps to help blind people to see with sound are based on exactly the same principle. The sound is given off by an ultrasonic (超声的) torch, whose shape is different from a normal electric torch. It is double-barreled. It works in a similar way to a sonar (声呐) unit on a warship or submarine. The unit's transmitter sends out pulses of ultrasonic waves at the same frequency as the bat and the receiver picks up the returning echoes. Because these are still above the frequency at which the human ear can pick them up. The echoes are filtered (过滤) through circuits that turn them into “bleeps” which can be clearly heard before passing them into headphones.

    This means that a person holding the torch can point it ahead of him and scan the area for obstacles over a range of about 25 feet. If there are no return echoes coming through the headphones, then there is nothing in the way. If echoes do come back, then the closer the obstruction the faster the succession of bleeps and the deeper the pitch of each bleep. With practice, the torch could help a blind person to lead a more normal life.

    At present, the experimental ultrasonic torch requires a shoulder bag to carry the batteries, cables for the power supplies and earphones, as well as the torch itself. Fortunately, reducing the size of the electronic equipment is progressing and it should not be long before the whole set-up can be reproduced in a form small enough to fit into a pair of glasses. The wearer would face in the direction he wanted to check, and lift or lower his head just as a sighted person would.

    When you cross deep water driving too fast, you risk splashing water up into the air box and having it get sucked into the internal engine, which is more common than you think. There are a few steps you should take to clear the water out before you try to start it:

    ⒈First, drain the fuel tank, fuel lines and the oil. While it's draining, put a fan on the wiring and dry it out. Remove and clean the carburetor (化油器).

    ⒉Take the plugs out of the engine and turn it over to force any water out. Water will come out with the oil. Add oil to the engine and turn it over again, without the plug in. Let it sit for a while, then observe the oil to tell if there's any water in it (it will look like a white milky substance if there is water mixed with the oil). If it's there, drain it again and start over until there is little or no white showing in the oil.

    ⒊Now re-install the spark plug, add gas, then try to start the engine. You should have a can of ether (乙醚) handy just in case it's stubborn, but don't use too much. If it starts, let it run for a few minutes without making it work faster.

    ⒋After it runs for several minutes, shut it off, drain the oil and change the filter(过滤网). Run it again for a few minutes then shut it off and checks again for milky colored oil. If you have none, you should be good to go.

    ⒌If you cannot start the engine, you may have already ruined it and you will probably need to seek a professional to repair it, or, more likely, you'll have to replace it.

    Captain America and Blackpanther were about to defend Earth from the criminal Thanos when Kevin Foley first noticed something was wrong. Foley, a 46-year old information-technology worker from Kyle, Texas, was heading into the theater to see Avengers: Infinity War when he realized he was having trouble breathing normally. The same symptom struck again during another movie the following night, but more severe this time. Once the cast on the second film rolled, Foley took action: he looked at his wristwatch. It was a bigger step than you might imagine, because Foley was wearing an Apple Watch equipped with medical sensors and experimental software to track basic functions of his heart. And the watch was worried. It had, according to the display, detected signs of an irregular heartbeat.

    Before long, Foley was in an emergency room, where doctors hooked him up to an ECG(心电图), which showed that he was in atrial fibrillation(心房颤动), an irregular heartbeat that can lead to blood clots(血栓), stroke and other potentially disastrous diseases. Foley spent the next few days in the hospital while doctors worked to return him to a normal heart rhythm eventually turning to a procedure called electrical cardioversion to shock his heart back to normal. Foley is doing fine now. But he believes that, if not for the warning on his watch, he might not have sought help in time. “I would have never known,” he says.

    Foley and his watch were part of an experiment run by Apple and Stanford's medical school. But beginning Dec. 6, anyone can get an on-the-fly heart checkup, assuming they've paid $399 or more for an Apple Watch. That's when Apple will launch a software update that turns its latest model, called the Series 4, into a personal ECG, thanks to an innovative new sensor. Though less complicated than hospital ECG machines, the watch version can still provide basic information and warnings of potential risks worthy of a closer look by a medical professional.

    For Apple, this new ECG-on-your-wrist is its biggest bet yet that personal technology will inevitably include personal health. Along with competitors, Apple has already offered fitness functions, such as apps to track the steps you've walked. But with the new ECG scan, Apple is moving straight into medical aspects of heath, a distinction underlined by the fact it sought and received Food and Drug Administration clearance for the clearance for the heart monitor.

    Are you looking for some new and exciting places to take your kids to? Try some of these places:

    Visit art museums. They offer a variety of activities to excite your kids' interest. Many offer workshops for making hand-made pieces, traveling exhibits, book signings(签名) by children's favorite writers, and even musical performances and other arts.

    Head to a natural history museum. This is where kids can discover the past from dinosaur models to rock collections and pictures of stars in the sky. Also, ask what kind of workshops and educational programs are prepared for kids and any special events that are coming up.

    Go to a Youtheater. Look for one in your area offering plays for child and family visitors. Pre-show play shops are conducted by area artists and educators where kids can discover the secret about performing arts. Puppet (木偶) making and stage make-up are just a couple of the special offerings you might find.

    Try hands-on science. Visit one of the many hands-on science museums around the country. These science play-lands are great fun for kids and grown-ups alike. They'll keep your child mentally and physically active the whole day through while pushing buttons, experimenting, and building. When everyone is tired, enjoy a fun family science show, commonly found in these museums.

    Wellington: Huawei has started a rugby-themed media campaign in a bid to win over New Zealand's public after the country's security agency blocked the Chinese technology giant's equipment from being used in a nationwide Internet network.

    "5G without Huawei is like rugby without New Zealand," ads in New Zealand's two largest newspapers read alongside a photo of players competing in a ball. Large posters also appeal to the country's love of the sport. In November, New Zealand's Government Communications Security Department (GCSD) told Spark it couldn't use equipment from Huawei-the world's largest telecommunication equipment company—in the building of its 5G network because an unspecific "significant network security risk was identified". Spark is now in the process of seeing if it can make changes to prevent those risks, although GCSD has declined to publicly say how that would happen.

    Huawei's newspaper ad goes on to argue the decision would mean less advanced technology and higher prices for New Zealand customers. The ads come after the company last month publicly offered to only use New Zealand, rather than Chinese, staff to build the network—in a bid to ease fears—and called for an urgent meeting with the government, denying (否认) there had been any wrongdoing.

    Western spy agencies have increasingly raised security concerns about Huawei—China's largest telecommunications company-over what they say are possible links to the Chinese government, with the United States reportedly pressing Five Eyes intelligence network allies (同盟国) to avoid the company. Australia and Canada were the first countries to ban Huawei from a building of 5G networks.

The company has repeatedly denied accusations.

    New Zealand's top politicians have repeatedly denied the GCSD decision was influenced by other Western powers and say it's about the particular technology being suggested, not China. They have also denied suggestions New Zealand's diplomatic ties with China have been tense over the decision, with the official promotion of a major China—New Zealand tourism project now postponed.

More than 100 scientists traveled to faraway places to collect wild crop seeds in an effort to help battle climate change. The scientists have been likened to the hero of the Indiana Jones movies. Like him, they had to face blood-sucking creatures and fierce tigers. Some-times, they had to use elephants for transportation because they couldn't find any other means of transportation.

A report on the project was published last week. It described the results of a six-year search to collect thousands of wild seeds. The seeds could be important in feeding a growing human population at a time when rising temperatures are affecting crop production in some areas.

The scientists traveled on foot, by four-wheeled vehicles, boat and riding horses and they even rode elephants to reach faraway areas. They collected 4,644 seed samples of 371 wild relatives of 28 crops. Many of those wild relatives are said to be endangered.

The Crop Trust, a nonprofit organization that works to save different kinds of crops, was directing the project. The group was working in partnership with Britain's Royal Botanic Gardens and Millennium Seed Bank. Additional financial support came from Norway. The project is believed to be the largest organized international effort yet to collect and protect crops' wild relatives.

Some relatives of widely grown crops have developed so they can survive usual and severe conditions such as low rainfall, flooding, extreme temperatures and poor soils. Scientists say the wild crops offer a largely unused source of diversity for protecting crops against climate change.

Some crops are threatened because of destruction of forests, conflict and expanded cities. Experts say losing this diversity could endanger food security around the world. A United Nations report says that food supplies are under severe threat. The report notes that the number of animal and plant species are quickly disappearing as the world deals with how to feed a rising population.