Thousands of persons in Peru are suffering from the disease cholera. Medical experts say it is the first time in their century that cholera has reached the western part of the world. The Untied States Centers for disease Control says the kind of cholera has been spreading throughout the world since 1961. It was discovered that year in Indonesia. Since the first case in Peru, more than sixteen thousand people have been affected and about one hundred have died.

    Cholera is caused by polluted food and water. People become infected (传染 ) when they eat the polluted food or drink the polluted water. If untreated immediately, they may die within hours. Most victims however , can be saved. treatment includes drugs and replacement of body fluids ( 液体) directly into the blood.

    Medical researchers have developed a vaccine ( 菌苗) medicines to protect against cholera. But the vaccine is only about 50% effective. And it protects against cholera for only about six months. Medical experts say the best way to fight cholera is to prevent it. They also say people should not eat uncooked food or food that has not been cooked long enough. People who live in areas where cholera has been found should wash their hands before eating and cooking. They should drink only water that has been boiled or made pure with chemicals.

    Imagine that you're looking at your company-issued smartphone and you notice an e-mail from Linkedln: “These companies are looking for candidates like you!” You aren't necessarily searching for a job, but you're always open to opportunities, so out of curiosity, you click on the link. A few minutes later your boss appears at your desk. “We've noticed that you're spending more time on Linkedln lately, so I wanted to talk with you about your career and whether you're happy here,” she says. Uh-oh.

     It's an awkward scene. Attrition (损耗) has always been expensive for companies, but in many industries the cost of losing good workers is rising, owing to tight labor markets. Thus companies are making greater efforts to predict which workers are at high risk of leaving ,so that managers can try to stop them. Methods range from electronic monitor to well-designed analyses of employees' social media lives.

     Some of this work may be a reason to let employees to quit. In general, people leave their jobs because they don't like their boss, don't see opportunities for promotion or growth, or are offered a higher pay; these reasons have held steady for years.

    New research conducted by CEB, a Washington-based technology company, looks not just at why workers quit but also at when. “We've learned that what really affects people is their sense of how they're doing compared with other people in their peer group, or with where they thought they would be at a certain point in life, says Brian Kropp, who heads CEB's HR practice. “We've learned to focus on moments that allow people to make these comparisons.”

Technology also provides clues about which star employees might be eyeing the exit. Companies can tell whether employees using work computers or phones are spending time on (or even just opening e-mails from) career websites, and research shows that more firms are paying attention to these things. Large companies have also begun searching for badge swipes (浏览痕迹)—- employees' use of an ID to enter and exit the building or the parking garage—to identify patterns that suggest a worker may be interviewing for a job.

    Tiny Countries You Never knew Existed

    Sao Tome and Principe

    Sao Tome and Principe off Africa's west coast is only 372 square miles, but it has Impressive, undamaged nature, rich in biodiverse species. The amazing needle-like volcanic peak Pico Cao Grande rises 1,000 feet into the air. The islands are home to only around 200,000 people today.

    San Marino

    Only 23 square miles with a population of just 34,000, the little-known country of San Marino, surrounded by Italy, is the world's fifth smallest country. With the UNESCO World Heritage Site of Mount Titano, the country is said to be the oldest republic in the world.

    Dominica

    Dominica covers only 290 square miles, with some of the best diving in the Caribbean, including the UNESCO World Heritage Site of volcanic Morme Trois Pitons National Park. In Dominica, you'll see rainforests, waterfalls, and coastal views. The island is also home to the only remaining population of the Kalinago, who are part of the island's 74, 900 inhabitants.

    Kiribati

    This Pacific island country 33 coral islands is 313 square-miles, but it's the only country in the world to fall into all four hemispheres (半球). The country's 109, 000 residents live in only 21 of the islands see this tropical paradise before it is no longer--rising seas are threatening to swallow the country whole.

    A new study shows students who write notes by hand during lectures perform better on exams than those who use laptops.

    Students are increasingly using laptops for note-taking because of speed and legibility(清晰度).But the research has found laptop users are less able to remember and apply the concepts they have been taught.

    Researchers performed experiments that aimed to find out whether using a laptop increased the tendency to make notes "mindlessly" by taking down word for word what the professors said

    In the first experiment, students were given either a laptop or pen and paper .They listened to the same lectures and were told to use their usual note-taking skills. Thirty minutes after the talk, they were examined on their ability to remember facts and on how well they understood concepts.

    The researchers found that laptop users took twice as many notes as those who wrote by hand. However, the typists performed worse at remembering and applying the concepts. Both groups scored similarly when it came to memorizing facts.

    The researchers' report said, "While more notes are beneficial, if the notes are taken mindlessly, as is more likely the case on a laptop, the benefit disappears."

    In another experiment aimed at testing long-term memory, students took notes as before but were tested a week after the lecture. This time, the students who wrote notes by hand performed significantly better on the exam.

    These two experiments suggest that handwritten notes are not only better for immediate learning and understanding, but that they also lead to superior revision in the future.

    You're probably used to the regular upgrades in our cell-phone networks. There was 2G, which came along in 199l, replaced with 3G in 2001, followed by 4G in 2009. Now we're hearing about the coming of 5G.

    But 5G is a much bigger leap than before. 5G, of course, is much faster than 4G in the real world and a 5G phone in a 5G city will enjoy Internet speeds between 9 and 20 times as fast. The arrival of 5G also means enormous leaps forward in capacity－so much that every cell-phone plan will offer cheap, truly unlimited Internet access. "The consequences of that are huge," says Sherif Hanna, Qualcomm's director of 5G marketing. For example, apps will no longer degrade (降低) your video quality or postpone downloading when you're out of Wi-Fi range. In fact, you'll probably prefer to do your downloads when you're on cellular (使用流量) because 5G will be much faster than whatever service you've got at home or work.

    "However, not everyone is excited by the 5G development. The new standard gets its speed partly by using existing transmission(传输) frequencies more efficiently and partly by using the millimeter wave range. That's a big, juicy line of radio frequencies that are currently underused because millimeter wave is really hard to use," Hanna says.

    These frequencies are much higher than anything we've used for the cellular, which means they can offer unbelievable speed－but at the cost of range. Millimeter wave cellular towers have to be about 500 feet apart. Cell carriers not only will have to upgrade all their cell transceivers (called small cells) but will install(安装) a lot more of them as well.

    That's why the millimeter wave flavor of 5G, the superfast coverage, will be available only in densely populated cities such as New York and San Francisco. In suburban and rural areas, 5G will bring a speedup of "only" nine times faster.