The expression “a thirst for knowledge" may soon have a new meaning for millions of people who have no way to get clean water. Researchers have developed a book with specially treated pages that can turn dirty water into clean and drinkable water. They say their invention could improve the lives of many in the developing world.

    About 700 million people around the world are at risk of disease or even death because their drinking water is not clean. The water is polluted by harmful bacteria.

    The book contains 25 pages. Each page is about one millimeter thick. The pages contain very small particles (微粒) of silver. The pages can be used as filters（过滤器）to remove harmful microorganisms (微生物) that can pollute drinking water. The filter kills the organisms that pass throughit.

    Pictures on the pages show the dangers of dirty water and how to use the book for those unable to read. The pages aremade of filter paper. They are designed to be torn from the book. Water can bepoured through the paper to be cleaned.

    Ms. Dankovich, the inventor, says eachpage can treat up to 100 liters of water. She recently presented her invention at the meeting of the American Chemical Society in Boston, Massachusetts. She was asked whether she had considered adding classic literature on the book's pages.

    "The idea of classic texts—that's of interest maybe later. We have discussed a little bit more exciting text. But we really haven't had the time to go through that part," she says.

    Teri Dankovich and another researcher tested the drinkable book in Bangladesh, Ghana and South Africa. The tests proved to be successful.

    Water for Life, a non-government alorganization, has provided financial support for the project.

    A recent study led by researchers from the National University of Singapore (NUS) has found a clear link between the color of a taxi and its accident rate. An analysis of 36 months of detailed taxi, driver and accident data from two fleets of yellow and blue taxis in Singapore suggested that yellow taxis have fewer accidents than blue taxis. The higher visibility (能见度） of yellow makes it less difficult for drivers to avoid getting into accidents with yellow taxis, leading to a lower accident rate.

    The study was led by Prof Ho. To test whether there was a relationship between the color of a taxi and the number of accidents the taxi had, the research team analysed data collected by the largest taxi company in Singapore. The researchers found that yellow taxis have about 6. 1 fewer accidents per 1,000 taxis per month.

    They also studied the economic effect of changing the color of the entire fleet of taxis to yellow. The Singapore taxi company involved in the study owns about 16,700 taxis in a ratio (比例) of one yellow to three blue taxis. If a commercial decision is made to switch from blue to yellow taxis, 76. 6 fewer accidents will occur per month or 917 fewer accidents per year.

    Assuming an average repair cost of $1,000 per car and a downtime of six days, the color of all taxis to yellow could produce an annual saving of $2 million.

    “We are eager to continue to validate (证实) the findings of our study by looking at the use of yellow in other types of public transport, such as school buses. For example, we hope to compare the accident rates of yellow school buses against those of other colors to find out if yellow is indeed a safer color for school buses. Besides, we' re also interested to look at private-hire vehicles and do a comparison of the accident rates of vehicles that are of different colors explained Prof Ho.

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    Written in the first chapter of the book Pride and Prejudice is an extraordinary sentence of which even a person who has had only a brief look upon the book will not fail to receive a deep impression — It is a truth universally acknowledged that a single man in possession of a good fortune must be in want of a wife. In terms of Sherlock Holmes, we'd better alter the sentence into “It is a fact universally accepted by readers throughout the world that an excellent book in possession of our famous detective Sherlock Holmes is undoubtedly a masterpiece of all times.” Perhaps this is one of the most obvious explanations for the unrivaled popularity of “Holmes series” in the field of detective stories. Overwhelmed by the recommendations provided by my friends, I decided to take a look on this Sherlock Holmes and the Duke's Son originally published by Oxford University Press.

    As a whole, this book is about a case concerning the Duke's missing son. Arthur, the Duke's son, was found out in a certain morning to have disappeared, accompanied with which was also the disappearance of the German teacher. The school master Dr. Huxtable then turned to the famous detective of the time Sherlock Holmes for help. Realizing how tough and important the case is, Holmes immediately made up his mind to accept the case and followed Dr. Huxtable back to Mackleton by train. Having formed a rough idea about the whole matter, Holmes probed into the case immediately and had a careful investigation of the entire area shortly after the arrival, during the process of which he discovered the body of the German teacher Heidegger. Finally, primarily due to his prominent ability as a detective, he managed to unravel the mystery.

    Having once started reading this fiction, I was completely immersed in the mysterious story. At the beginning, unlike other detective stories, this story first delineates the client's strange behavior at length to indicate the severity of the incident in order to attract the readers to continue reading it. As is known to all, vivid depiction is essential to detective stories as it makes the story more authentic and attractive. Therefore, trying to present a “real world” to his readership, Sir Arthur Conan Doyle, author of the original “Holmes series”, has skillfully arranged the plots of the whole story from the perspective of Dr. Watson, a friend of Homes'. In this way, he elaborately (精心)depicted every scene and character in the book. Apart from the special start, the ending of the whole story, being dramatic but reasonable, is certainly an outstanding one. After all, except the author himself, who knows that the Duke's seemingly ordinary secretary is in fact the Duke's bastard(私生子)? In addition, who knows that the Duke actually has already been acquainted with the whole thing before Holmes solves this complicated problem? Yet, surprising as it is, this ending seems so natural that it fits all the plots of the story perfectly well. Closing my eyes, I can even “see” the story happening just like watching a film.

    As far as I am concerned, nothing is more admirable and surprising in the hero Sherlock Homes than his profound knowledge which has certainly assisted him a lot when he was studying the case. Take the bicycle tyres for instance, Holmes is capable of recognizing 42 different varieties of bicycle tyres. Except for his illimitable knowledge, Holmes also specializes in arranging the facts in order and then finding the fact leading him to a great discovery or even the truth itself. In this case, after getting rid of unrelated facts, Sherlock Homes eventually grasped the clue and discovered the amazing fact.

    Needless to say, as a world-renowned masterpiece, Sherlock Holmes and the Duke's Son has attracted and is still charming numerous readers from all corners of the world and people from all walks of life. The “Holmes series” has already set up a standard against which all the following detective fictions are measured. Sherlock Holmes, beyond all doubt, has been a name firmly rooted in people's memories. Although Dr. Watson's closing The Case Book of Sherlock Holmes in 1927 was a great pity to the readers, the discontinuance of the entire “Holmes series” may have actually added to the legendary stature of Sherlock Holmes.

    The stories we share with one another are important. They show wisdom and provide inspiration. They are important to our development. But sometimes people choose not to tell.

    Consider the negative effects of not sharing a story in the news: People are wondering if public health officials are holding back too much information about the recent outbreak of Ebola.

    There is a danger in holding back stories that ought to be told. Bobette Buster said it like this, “The fact is that history has shown us that stories not told can become like a dangerous genie (妖怪) left in a bottle. When they are finally uncorked, their power to destroy is set free.”

    There are a number of reasons why we hide parts of our story: they often show our weaknesses or expose our disadvantages; they require courage and strength to share; and of course, there are some stories that should be kept secret—especially those that embarrass someone else.

    Most of us have two selves: the one we display on the outside and the one we actually are on the inside. And the better we get at hiding the stories that show our true selves, the more damage we may be causing to ourselves and to others.

    Honesty and openness is important: It proves we are trustworthy. It displays we are human. We are not perfect or better. It highlights the importance of hard work and personal development. Hard work may not allow us to overcome our disadvantages completely. But with hard work, we do not have to be limited to our mistakes.

    Does this mean we admit every weakness, every disadvantage, and every secret regret to everybody we meet? No, of course not. There is a time and a place and a certain level of relationship necessary for some stories to be told in an appropriate manner.

    British writer John Donne once said: “No man is an island; every book is a world.” As an enthusiastic reader, I can't agree with the latter part of the sentence more. Every summer, I endeavor to find some peaceful places where I can attack some classics without being disturbed. Thomas Hardy wants to live far from the madding crowd. I am no friend to chaos, either.

    I read George Orwell's 1984 in a New England beachside cottage with no locks on the doors, no telephones or televisions in the rooms. 1984 is a good book that needs deep reflection. Attempting Sound and Fury lying on the bed of a poorly-occupied motel, however, was less fruitful: I made it through one and a quarter volumes, but then my eyelids were so heavy that I couldn't keep them open.

    But this summer I find myself at a loss. I'm not quite interested in J.D.Salinger, say, or Frankenstein. There's always War and Peace which I've covered some distance several times, only to get bogged down in the “War” part, set it aside for a while, and realize that I have to start over from the beginning again, having forgotten everyone's name and social rank. How appealing to simply fall back on a favorite—once more into The Call of the Wild or Alice in the Wonderland, which feels almost like cheating, too exciting and too much fun to properly belong to serious literature.

    And then there's John Steinbeck's The Grapes of Wrath. This title does not amaze but confuse. We're never short of sour grapes, but we've never heard of angry grapes. Anyway grapes are my favorite fruit of summer. These stone fruits can always make me feel cheerful and peaceful all at once.

    THREE years ago Jenny Salgado, a Dominican shop assistant, moved to Highland town, a neighborhood of Baltimore. When she arrived the shop she works in, it was one of only a few Spanish businesses. Now there are many more. "It's good now if you speak Spanish," she smiles.

    Baltimore has been losing people for 60 years. To address this, its mayor, Stephanie Rawlings-Blake, wants to make it the most immigrant-friendly city in the world. Its libraries provide Spanish-language exercise classes. To help those with no papers, the city is introducing micro-loans (小额贷款) which require no credit checks; city police would no longer routinely check the immigration status of citizens or enforce any federal immigration law unless required to. The then governor, Martin O'Malley made it possible for illegal immigrants to get driving licenses.

    Such welcoming policies are spreading. Such cities as Cleveland, Dayton and Philadelphia all eagerly try to please immigrants. Rick Snyder, the governor of Michigan, has asked the federal government to offer 50,000 visas to people who agree to live in Detroit. His administration has made it easier for skilled migrants to get professional licenses.

    When a city's population falls, both tax receipts and services fall. Half-deserted neighborhoods breed (滋生) crime, driving yet more people to leave. No city has escaped this death circle without attracting new residents, says Steve Tobocman of Global Detroit.

    Several studies suggest that when immigrants arrive, crime goes down, schools improve and shops open up. In Detroit, immigrants living near the tiny separate city of Hamtramck have formed local watches to guard against thieves. Their neighborhoods are not just safer; they are also among the only places where it is as easy to buy fresh vegetables as drugs and alcohol.

    But attracting new immigrants to the cities which most need them is hard, argues Audrey Singer of the Brookings Institution. They care about the same things as everyone else: safe streets, good schools and jobs. Cities which have lost population for decades struggle with all of these.