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西安市儿童医院胃病胃肠正规吗?怎么样飞度【动态新闻网】

楼主:飞度新闻权威医院 时间:2019年04月21日 06:10:42 点击:0 回复:0
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Science and Technology Flying snakes Slithering through the air科技 飞蛇 空中滑行Fancy aerodynamics explain why some snakes are good gliders奇特的气体力学解释了为什么一些蛇善于飞行MANY animals have mastered the trick of gliding through the forest canopy. Flying frogs stretch the webbing between the toes of their enlarged feet. Some lizards sp elongated ribs covered in flaps of skin. And the colugo, a strange South-East Asian mammal, can travel as much as 70 metres (230 feet) between trees by sping a membrane of skin that connects its limbs. Despite a lack of obvious body parts that can double up as a decent pair of wings, some snakes, too, can glide for remarkable distances.许多动物掌握在林冠中滑行的技巧。青蛙在飞行时展开它的脚蹼;一些蜥蜴展开皮肤软组织下的细长肋骨;猴猫,一种生长在东南亚的哺乳动物,通过伸展连接四肢的薄膜在树中滑行多达70米(230英尺)。尽管身体明显缺少一部分,如一对能够拍打且适于滑行的翅膀,一些蛇也能飞行很远。To discover how snakes manage it Jake Socha of Virginia Tech and his colleagues conducted a series of test flights with paradise tree snakes, a mildly venomous variety found in parts of Asia. They launched the snakes from the top of a 15-metre tower and used four cameras to construct 3-D images of the animals trajectories. The results, just published in Bioinspiration and Biomimetics, show not only that flying snakes are surprisingly good aviators but also that they employ some complex aerodynamic tricks.为了查明蛇类如何成功的飞行很远,维吉尼亚理工学院的Jake Socha和其同事用一些天堂树蛇做了一系列的飞行试验,这是一种毒性适中的蛇,它生长在亚洲部分地区。研究人员使树蛇从15米高的塔顶端飞行,过程中使用了4个摄影机拍摄蛇滑行的轨迹,以拍摄成三维立体图像。不久前在生物灵感和仿生学上发布的结果显示:飞蛇的飞行不仅令人叹为观止,并且飞行过程中使用了一些在空气动力方面的很复杂的技巧。A paradise tree snake flattens its body into an aerofoil-like shape that can provide a degree of lift before it takes off from a branch by jumping upwards. It then falls at a steep angle and starts undulating from side to side. As it gains speed its glide path becomes shallower, allowing it to cover a greater distance. The researchers found some snakes could glide for 24 metres.天堂树蛇展平它的躯体,使其形成机翼般的形状,这可以使它在借助树干弹跳前产生一定的提升力。然后它急剧下降并且不停地摆动身体。随着下降速度的增加,下滑道变得越来越浅,这使树蛇滑翔很长一段路程。研究人员发现一些树蛇可滑翔24米。The 3-D analysis showed the snakes take up a staggered posture when gliding, with their bodies angled upwards at about 25° to the oncoming air and their heads slightly higher than their tails. Dr Socha says this orientation seems to provide the creatures with an aerodynamic advantage. As a result of it, the wake of air forced backwards by one segment of the snakes undulating body may provide extra lift to the segment behind in the sidewinding glide. Flying fish rely on a similar flow of accelerated air from their pectoral fins to provide lift to their smaller pelvic fins. Indeed, it is possible that the effect works both ways, and that rearward segments provide lift to those in front.对三维立体图像的分析表明:树蛇滑翔过程中摆动着身体,躯体向上抬,与迎面的空气呈25度角,头部稍微高于尾部。Socha士表示在空气动力学角度上来讲,这样的身体趋向可能会对飞行的树蛇产生推助的作用。这样,摆动树蛇的身体的前半部分擦过的空气尾流可对侧风滑行的后半部分起到提升的作用。同样,飞鱼借助胸鳍所产生的加速气流,就可以对较小的腹鳍产生一定的提升作用。事实上,反过来也可能产生这种效果,即后半部分可为前半部分起到提升作用。The snakes are also surprisingly manoeuverable and have been seen to turn in mid-air. To find out if this might be deliberate, Dr Socha limited their view from the tower so that they could see only straight ahead when they launched themselves. Once airborne, and thus able to observe trees to the side of their glide-paths, some of the snakes turned towards them.树蛇的飞行技巧也也令人叹为观止。人研究人员观察到它们在飞行途中可以变向。为了探明树蛇是否故意发出这一行为,Socha士限制了树蛇在飞行时的视野,目的是让他们在起飞时只能向前看。一起飞,这些树蛇就可以看到滑行路径两旁的树,一些就转变方向朝树木飞去。Dr Socha, who studies the relationship between form and function in animals, was partly funded in his snake research by Americas Defence Advanced Research Projects Agency, which said it was interested in the science but obviously wonders about military applications.研究动物的构成和功能的Socha 士在对蛇进行研究时得到了美国国防发展研究项目的资助,它称它对这部分科学很感兴趣,但也明显质疑是否可以将这部分科学应用到军事领域。Dr Socha does not expect to see snakelike drones in the skies soon. However, the ability to slither through holes, to swim and to climb trees and rocks, as well as to glide between elevated features of the landscape, is an attractive mixture for designers of robotic vehicles. The staggered-wing effect, in which the front of the body helps to provide lift for the back, may also be of interest to aircraft engineers. In the long term, then, the worlds battlefields may see machines that resemble some peoples worst nightmares, slithering as they do towards the enemy both on the ground and through the air.Socha士并未预期蛇形般的遥控飞机即将腾空出世,然而,设计集各种功能于一身的交通工具-全部自动化,能够滑穿孔洞,穿行在水中,爬得大树和岩石,滑行在凹凸不平的风景中-对于设计师来说,很具吸引力。摆动的双翼所产生的效果-机身的前半部分可为后半部分增加提升力,对飞机工程师来说也可能颇感兴趣。从长远来看,在世界战场可以看到那些出现在一些人的噩梦里的飞机,在陆地和空中滑翔,攻打敌人。 /201301/22Business.商业。Libraries and e-books图书馆和电子书Literary labours lent文学劳动力已借出The uncertain economics of lending virtual books难以预料的实体书借阅经济LIKE a tired marriage, the relationship between libraries and publishers has long been reassuringly dull. E-books, however, are causing heartache. Libraries know they need digital wares if they are to remain relevant, but many publishers are too wary of piracy and lost sales to co-operate. Among the big six, only Random House and HarperCollins license e-books with most libraries. The others have either denied requests or are reluctantly experimenting. In August, for example, Penguin will start a pilot with public libraries in New York.就像是一个令人疲惫的婚姻,图书馆和出版商之间长期存在着无聊的关系。然而,电子书的出现引起了它们的心痛。图书馆知道,如果它们想保持自己存在的价值,就需要数字化的设备,但对于许多出版商而言,由于在盗版和失去销量问题上太过谨慎的态度,而不予合作。在最大的六家出版商中,只有兰登书屋和哈珀?柯林斯出版社授予了绝大多数图书馆电子书的许可。其它出版社或是拒绝了这项要求,或是在勉强进行试用。例如,在八月份,企鹅出版社将在纽约的公共图书馆开始试验。Publishers are wise to be nervous. Owners of e-ers are exactly the customers they need: book-lovers with money (neither the devices nor broadband connections come cheap). If these wonderful people switch to borrowing e-books instead of buying them, what then?出版商感到紧张是明智的。电子阅读器的所有者们恰恰是他们需要的顾客:有钱(而既不是设备或是便宜的宽带连接)的爱书人。如果这些了不起的人们由借阅电子书而变为购买电子书,将会怎样呢?Electronic borrowing is awfully convenient. Unlike printed books, which must be checked out and returned to a physical library miles from where you live, book files can be downloaded at home. Digital library catalogues are often browsed at night, from a comfy sofa. The files disappear from the device when they are due (which means no late fees, nor angst about lost or damaged tomes).电子借阅非常方便。与印刷版书籍不同,电子书籍文件在家就可以下载,而不需要去离家几英里外的实体图书馆借阅和还书。人们常在晚上在舒适的沙发里浏览数字图书馆目录。当文件到期时,它们将自动从设备上消失(这意味着没有滞纳金,也无需担心丢失或损坏煌煌巨著)。Awkwardly for publishers, buying an e-book costs more than renting one but offers little extra value. You cannot resell it, lend it to a friend or burn it to stay warm. Owning a book is useful if you want to savour it repeatedly, but who s ;Fifty Shades of Grey; twice?这对出版商而言却很尴尬。购买一本电子书比租用一本的花费更多,然而带来的收益增加却相当微小。你不能把电子书二次售出或是借给朋友,甚至不能将它烧了以取暖。如果你想重复品味一本书,那么拥有一本书是非常好的,但谁愿意读第二遍《格雷的50道阴影》?E-lending is not simple, however. There are lots of different and often incompatible e-book formats, devices and licences. Most libraries use a company called OverDrive, a global distributor that secures rights from publishers and provides e-books and audio files in every format. Some 35m titles were checked out through OverDrive in 2011, and the company now sends useful data on borrowing behaviour to participating publishers. Yet publishers and libraries are worried by OverDrives market dominance, as the company can increasingly dictate fees and conditions.然而电子借阅并不简单。电子书的格式、设备和许可之间有极大不同,并常常不能互相兼容。大多数图书馆所采用的是OverDrive公司提供的电子书,这家全球性经销商确保了来自出版商的版权,并提供所有格式的电子书和音频文件。2011年,高达三亿五千万的条目通过OverDrive公司借出,这家公司现在正通过输出借阅行为相关的有用数据参与到出版商中来。OverDrive的市场占有率让出版商和图书馆担忧,因为这家公司可以提高授权费用和条件。Publishers were miffed when OverDrive teamed up with Amazon, the worlds biggest online bookseller, last year. Owners of Amazons Kindle e-er who want to borrow e-books from libraries are now redirected to Amazons website, where they must use their Amazon account to secure a loan. Amazon then follows up with library patrons directly, letting them know they can ;Buy this book; when the loan falls due.去年,当OverDrive公司与世界上最大的在线图书销售商——亚马逊合作之后,出版商们有点恼火。亚马逊Kindle阅读器的所有者们现在如果想从图书馆借阅电子书,就将被带入到亚马逊的网站上,在那里,他们必须使用他们的亚马逊账户来为他们的借阅提供担保。亚马逊还进一步与图书馆的老主顾们直接交涉,告诉他们若是借阅过期,则他们可以直接;购买这本书;。This arrangement nudged Penguin to end its deal with OverDrive earlier this year. The publishers new pilot involves 3M, a rival distributor that does not yet support the Kindle. ;Ultimately Amazon wants to control the library business,; says Mike Shatzkin, a publishing consultant.这一约定迫使企鹅出版社在今年早些时候终止了它和OverDrive的合约。这家出版商的新合作者包括3M公司,OverDrive的竞争对手之一,一家尚未持Kindle的经销商。;亚马逊最终想控制图书馆事务。;出版业咨询师麦克?肖特金说。Library users-nearly 60% of Americans aged 16 and older, according to Pew, an opinion researcher-are a perfect market for Amazon. It woos them by making loans on the Kindle uniquely easy. Late last year Amazon also unveiled its Kindle Owners Lending Library, which lets its best customers (called ;Amazon Prime; members) borrow free one of thousands of popular books each month.根据民意调查研究机构皮尤的数据,16岁以上并占美国人口数近60%的图书馆使用者,是亚马逊最好的市场。它通过在Kindle上极其便利的借阅程序,从而取悦了他们。去年晚些时候,亚马逊还推出了Kindle所有者的借阅图书馆,这个图书馆允许亚马逊最好的客户(被称为;亚马逊会员;的成员)每月在上千本畅销书中免费借阅一本。Library boosters argue that book borrowers are also book buyers, and that libraries are vital spaces for ers to discover new work. Many were cheered by a recent Pew survey, which found that more than half of Americans with library cards say they prefer to buy their e-books. But the report also noted that few people know that e-books are available at most libraries, and that popular titles often involve long waiting lists, which may be what inspires people to buy.图书馆的持者认为,借阅图书者也就是购买图书者,而图书馆则是这些读者发现新作品的重要根据地。许多人为皮尤研究机构最近的调查而感到欢欣鼓舞,这项调查发现,超过一半拥有图书馆卡的美国人说,他们更喜欢购买他们的电子书。但是这项报告也指出,几乎没有人知道电子书在大多数图书馆都是可借阅的,而那些畅销书籍常常有着很长的等候借阅名单,这也许将促进人们的购买行为。So publishers keep tweaking their lending arrangements in search of the right balance. Random House raised its licensing prices earlier this year, and HarperCollins limits libraries to lending its titles 26 times. Penguin plans to keep new releases out of libraries for at least six months, and each book will expire after a year. Hachette is engaged in some secret experiments, and the others are watching with bated breath. In Britain the government will soon announce a review of the matter. The story of the library e-book is a nail-biter.因此出版商在不断微调他们的借阅合约以找到最恰当的平衡点。兰登书屋在今年早些时候提高了授权价格,哈珀?柯林斯出版社限制图书馆借阅条目的次数为26次。在企鹅出版社的计划中,新书从出版后到进入图书馆,至少要等六个月的时间,且一年后就到期。阿歇特出版社正在进行一些秘密实验,而其它出版社则在屏息观望。在英国,政府不久将宣布一份这一事项的报告。电子图书馆的故事实在是一个令人高度紧张的故事。 201208/193681The inquisition had succeeded in stifling one of the most humane voices in the climate of increasing paranoia.宗教裁判所已成功地抑制这增加偏执氛围中最具人性感觉的一种声音。But it wasnt just religious scholarship that the inquisition repressed.但宗教裁判所压抑的不只是宗教学术。Professor Jose Louis Marcelo is the guardian of a unique text, one that shows how the inquisition invented the dark art of thought control.何塞·路易斯·马塞洛教授是《卫报》的一位独特的记者,他展示了宗教裁判所如何发明了思想控制黑暗的艺术。So you covered the pages up?所以你覆盖了这一页?What are the methods did they?他们是有什么方法?So these are dangerous ideas.这些都是危险的想法。Wow, incredible!哇,不可思议! 注:听力文本来源于普特201302/224425

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