南方医科大学北滘医院割包皮大河咨询

明星资讯腾讯娱乐2019年07月19日 06:18:55
0评论
Science and technology科学和技术Computer vision计算机模拟视觉Eye robot你是我的眼Poor eyesight remains one of the main obstacles to letting robots loose among humans.放手让机器人在人类社会自由活动仍存在重大障碍—它们看不清楚。But it is improving, in part by aping natural vision.然而人工视能正在逐渐提高,途径之一就是模拟自然视觉。ROBOTS are getting smarter and more agile all the time.机器人的反应总是在变得越来越灵活,动作也越来越敏捷。They disarm bombs, fly combat missions, put together complicated machines, even play football.它们会拆卸炸弹、驾驶战斗机执行任务、组装复杂机械,甚至还会踢足球。Why, then, one might ask, are they nowhere to be seen, beyond war zones, factories and technology fairs?那么,人们不禁要问,为什么除了在战场、工厂和科技产品展销会,生活中都看不到机器人的踪影呢?One reason is that they themselves cannot see very well.一个原因就是它们自己眼神不大好。And people are understandably wary of purblind contraptions bumping into them willy-nilly in the street or at home.机器人跟睁眼瞎差不多,要是把它们弄到大街上,或者摆在家里,搞不好就没头没脑地把人给撞了——对这玩意儿谨慎一点也是人之常情。All that a camera-equipped computer sees is lots of picture elements, or pixels.装有摄像头的计算机能看到的一切,仅仅是大量的图像元素,又称像素。A pixel is merely a number reflecting how much light has hit a particular part of a sensor.像素只不过是一个数值,反映照到传感器某个部位的光线亮度是多少。The challenge has been to devise algorithms that can interpret such numbers as scenes composed of different objects in space.困难在于,要编写出一套计算程序,可以把这些数字再现为空间中不同物体构成的景象。This comes naturally to people and, barring certain optical illusions, takes no time at all as well as precious little conscious effort.这一切对于人类来说,只是一种本能—除非出现某些错觉—立杆而见影,在意识上可谓不费吹灰之力。Yet emulating this feat in computers has proved tough.然而事实明,在计算机上模拟人的这一天赋实非易事。In natural vision, after an image is formed in the retina it is sent to an area at the back of the brain, called the visual cortex, for processing.自然视觉的过程是:视网膜成像后,图像被传送到大脑后部叫做视觉皮层的地方,在那里进行信息处理。The first nerve cells it passes through react only to simple stimuli, such as edges slanting at particular angles.图像经过的第一组神经元只能对简单的视觉刺激作出反射,例如物体朝某些角度倾斜的边缘。They fire up other cells, further into the visual cortex, which react to simple combinations of edges, such as corners.第一组神经元又将兴奋传给视觉皮层更深处的神经元,这些神经细胞可以对简单的物体轮廓作出反应,例如空间中的角落。Cells in each subsequent area discern ever more complex features, with those at the top of the hierarchy responding to general categories like animals and faces, and to entire scenes comprising assorted objects.越往后,神经元能识别的图像特征越复杂,最高级别神经区域可以对动物和脸等总体类别作出反应,最后将包罗万象的场景整合到一起。All this takes less than a tenth of a second.而整个过程只需要不到十分之一秒。The outline of this process has been known for years and in the late 1980s Yann LeCun, now at New York University, pioneered an approach to computer vision that tries to mimic the hierarchical way the visual cortex is wired.很早以前,人们就已经了解这一过程的大致情形。二十世纪80年代末,现就职于纽约大学的雅安?勒存率先涉足计算机视觉研究,试图模拟人脑视觉皮层内神经元层层递进的布线方式。He has been tweaking his convolutional neural networks ever since.从那时起,他就一直在调整和改良他的卷积神经网络。Seeing is believing眼见为实A ConvNet begins by swiping a number of software filters, each several pixels across, over the image, pixel by pixel.卷积神经网络首先用几个软件滤光器,对图像逐一像素地进行扫描,每个滤光器只能通过几个像素。Like the brains primary visual cortex, these filters look for simple features such as edges.就像大脑的初级视觉皮层,这些滤光器只负责收集物体边缘等简单图像特征。The upshot is a set of feature maps, one for each filter, showing which patches of the original image contain the sought-after element.结果得到一组特征图,每一张特征图对应一个滤光器,显示出原始图像中的哪些块包含要筛选到的要素。A series of transformations is then performed on each map in order to enhance it and improve the contrast.随后,每一张特征图都要进行一系列调整,以提高它的画质、改善它的明暗对比度。Next, the maps are swiped again, but this time rather than stopping at each pixel, the filter takes a snapshot every few pixels.接下来,对这些特征图再次进行扫描,但这一次,滤光器不会在像素上逐一停留,而是每几个像素快拍一次。That produces a new set of maps of lower resolution.这样,得到一组新的分辨率较低的特征图。These highlight the salient features while reining in computing power.这些步骤凸显图像最显著的特征,同时对计算资源进行严格控制。The whole process is then repeated, with several hundred filters probing for more elaborate shapes rather than just a few scouring for simple ones.然后,将整个过程重复一遍,用几百个滤光器探查更为精细的物体形状,而不是随便扫视一些简单的形状。The resulting array of feature maps is run through one final set of filters.由此得到的特征图阵列,被输送经过最后一组滤光器。These classify objects into general categories, such as pedestrians or cars.它们可以对物体进行大体归类—是行人还是汽车等等。Many state-of-the-art computer-vision systems work along similar lines.许多尖端计算机视觉模拟系统都采用类似的原理运行。The uniqueness of ConvNets lies in where they get their filters.卷积神经网络的独特之处在于它们的滤光器已经做得登峰造极。Traditionally, these were simply plugged in one by one, in a laborious manual process that required an expert human eye to tell the machine what features to look for, in future, at each level.以往,滤光器只是一个接一个地接通。这一过程由手工完成,极为繁琐,需要一名专家全程用肉眼观察,然后向机器下达指令,告诉它下一步检索什么样的特征。That made systems which relied on them good at spotting narrow classes of objects but inept at discerning anything else.于是,依靠手动操作滤光器的计算机视觉系统,可以识别的物体类别十分有限,而无法分辨其他更多的东西。Dr LeCuns artificial visual cortex, by contrast, lights on the appropriate filters automatically as it is taught to distinguish the different types of object.相比之下,勒存士的人工视觉皮层,可以在按照设定程序识别不同类型的物体时,自动接通相应的滤光器。When an image is fed into the unprimed system and processed, the chances are it will not, at first, be assigned to the right category.把一张图像输入他的系统进行处理,如果这个系统没有预先存储任何资料,第一次使用时体统有可能会把这张图像错误归类。But, shown the correct answer, the system can work its way back, modifying its own parameters so that the next time it sees a similar image it will respond appropriately.但是,告诉它正确之后,系统将重新识别图像,并修改自身的参数,以便下一次再看到类似的图像,可以做出恰当的回应。After enough trial runs, typically 10,000 or more, it makes a decent fist of recognising that class of objects in unlabelled images.经过足够的试运行之后——通常需要进行1万次以上——要在未经标示的图像上识别那一类物体,卷积神经网络可以完成得相当出色。This still requires human input, though.然而,这个阶段还是需要人类对其进行信息输入。The next stage is unsupervised learning, in which instruction is entirely absent.下一个阶段为无监督学习,在这个过程中没有任何人的指导。Instead, the system is shown lots of pictures without being told what they depict.是的,向勒存的计算机视觉系统展示大量图片,不告诉系统图上画的是什么。It knows it is on to a promising filter when the output image resembles the input.如果输出的图像和输入的图像几乎一样,系统就知道自身的滤光器升级了。In a computing sense, resemblance is gauged by the extent to which the input image can be recreated from the lower-resolution output.在计算机学上,两张图片是否相像的判断标准是,像素较低的输出图像可以在多大程度上复原为输入的图像。When it can, the filters the system had used to get there are retained.一旦可以还原,为系统所用而达到这种效果的滤光器就被保留下来。In a tribute to natures nous, the lowest-level filters arrived at in this unaided process are edge-seeking ones, just as in the brain.在这个体现自然界智能的过程中,在无人辅助阶段,滤光器达到的最初等级为物体边缘搜索,正如人脑中的情形一样。The top-level filters are sensitive to all manner of complex shapes.最高等级的滤光器各种光怪陆离的形状都十分敏感。Caltech-101, a database routinely used for vision research, consists of some 10,000 standardised images of 101 types of just such complex shapes, including faces, cars and watches.加州理工101是进行视觉研究常规使用的数据库,它存储了约1万幅标准化图像,描述101类和标准化图像复杂程度相当的物体形状,包括脸、汽车和手表等。When a ConvNet with unsupervised pre-training is shown the images from this database it can learn to recognise the categories more than 70% of the time.当给事先经过无人监督训练的卷积神经网络展示这个数据库中的图像时,它可以通过学习辨认图像的类别,成功几率超过70%。This is just below what top-scoring hand-engineered systems are capable of—and those tend to be much slower.而最先进的手动视觉系统可以做到的也只比这个高一点点—并且它们的辨认速度往往慢得多。This approach which Geoffrey Hinton of the University of Toronto, a doyen of the field, has dubbed deep learning need not be confined to computer-vision.勒存的方法多伦多大学的杰弗里?希尔顿是该领域的泰斗,他将这一方法命名为深度学习不一定局限于计算机视觉领域。In theory, it ought to work for any hierarchical system:language processing, for example.理论上,该方法还可以用在任何等级系统当中,譬如语言处理。In that case individual sounds would be low-level features akin to edges, whereas the meanings of conversations would correspond to elaborate scenes.在这种情况下,音素就是语言识别的初级特征,相当于模拟视觉中的物体边缘,而对话的含义则相当于复杂场景。For now, though, ConvNet has proved its mettle in the visual domain.然而,目前卷积神经网络已经在视觉领域大显神威。Google has been using it to blot out faces and licence plates in its Streetview application.谷歌一直在街道实景应用程序中使用该系统,识别人脸和车牌,对其进行模糊处理。It has also come to the attention of DARPA, the research arm of Americas Defence Department.它还引起了美国国防部高等研究计划局的注意。This agency provided Dr LeCun and his team with a small roving robot which, equipped with their system, learned to detect large obstacles from afar and correct its path accordingly—a problem that lesser machines often, as it were, trip over.他们为勒存士和他的团队提供了一个漫游机器人,给它装上卷积神经网络系统后,这个机器人学会了探测远处的大型障碍物,并相应地纠正行进路线—可以说,没有安装该系统的机器人通常都会在这个问题上绊住。The scooter-sized robot was also rather good at not running into the researchers.这个漫游机器人只有小孩玩的滑板车那么大,却还相当有眼色:它不会撞向研究人员。In a selfless act of scientific bravery, they strode confidently in front of it as it rode towards them at a brisk walking pace, only to see it stop in its tracks and reverse.研究人员们发扬科学家舍身忘我的大无畏精神,做了一个实验:当机器人步履轻盈地向他们开过来时,他们突然昂首阔步迎面冲向机器人。结果发现,机器人半路停下并转向。Such machines may not quite yet be y to walk the streets alongside people, but the day they can is surely not far off.当然,这类机器人要走上街头与人为伍,或许还略欠火候。但是,它们可以自由行走那一天想必已经不远了。 /201302/224210

Business E-ers Turning the page商业 电纸书 微软和Bamp;N相逢一笑泯恩仇Microsoft and Barnes amp; Noble write their own love story微软和Barnes amp; Noble共写爱情故事。LAST July Barnes amp; Noble gave a presentation to the antitrust division of Americas Department of Justice. In slide after slide, the bookseller laid into Microsoft. The software giant, it thundered, was guilty of ;anti-competitive behaviour; in demanding royalties from makers of mobile devices (such as the Nook, Barnes amp; Nobles e-er) that used Android, Googles open-source mobile operating system. The bookseller sniffed that Microsoft owned only ;trivial; patents and reminded the department of the software companys past trespasses against competition.去年七月Barnes amp; Noble向美国司法部反托拉斯部门做了一个演示。Barnes amp; Noble的每张幻灯片都在攻击微软。它怒斥微软这家软件巨头违法,因为微软向生产使用安卓(谷歌的手机开源操作系统)移动设备的厂商收取专利使用费是;反竞争行为;(例如Barnes amp; Noble的电子书阅读器Nook)。Barnes amp; Noble讥讽微软只拥有一些不重要的专利并向提醒司法部微软以往的反竞争行为。Nine months later, the bookworms and the geeks are the best of friends. On April 30th Barnes amp; Noble said it was creating a subsidiary, called NewCo for now, into which it would put Nook and its ;college; business, which has 641 bookshops on American campuses. Microsoft is putting up 0m for 17.6% of NewCo. People will be able to buy and e-books through a Nook application for Windows 8, a new incarnation of Microsofts operating system that is due to appear in a few months. Microsoft will pay NewCo an advance of 0m over three years for such purchases, plus 5m over five years to buy content and develop technology. The squabbles over patents have been settled: Microsoft is giving Barnes amp; Noble a licence for the Nook and will get royalties in return. For now at least, the Nook will remain an Android, not Windows, device.九个月后,书虫和极客成为了最好的朋友。4月30日,Barnes amp; Noble宣布成立名为NewCo的分公司,该公司主营Nook和在美国校园拥有641家书店的;高校;业务部。微软注资3亿美元,拥有17.6的股份。人们将能通过WIN8版Nook应用购买和阅读电子书。WIN8是微软的新版操作系统,将在数月后问世。微软将会提前付1.8亿美元的三年使用费,并付额外的1.25亿美元用于之后五年的内容购买和技术开发。专利之争已经平息:微软给予Barnes amp; Noble的Nook许可并获得专利使用费。最起码就目前而言,Nook将仍然是安卓阵营成员而非windows成员。The agreement values NewCo at .7 billion, more than twice Barnes amp; Nobles market capitalisation before it was announced. The booksellers share price rose by 50% on the day of the deal—which tells you what investors think of the dead-tree end of the trade. The alliance should bring Barnes amp; Noble not only cash but also new ers of digital books and magazines, especially outside the ed States. In the fourth quarter of 2011, according to Tom Mainelli of IDC, a research firm, Barnes amp; Noble accounted for one-fifth of the 7m e-ers shipped in America—against a mighty three-quarters for Amazon, maker of the Kindle (see chart). But Barnes amp; Noble shipped no Nooks elsewhere, which helps explain why it had only 14% of the global market. Via the Nook app, non-Americans will also be able to leaf through Barnes amp; Nobles digital catalogue.协议中将NewCo估价为17亿美元,超过协议公布前Barnes amp; Noble市值的两倍。协议达成当天Barnes amp; Noble股价上涨50%,这表明投资者对这个实体书过时行业的看法。两公司联合不仅仅给Barnes amp; Noble带来资金还要带来新的电子书刊读者,尤其是美国外的读者。调查机构IDC的Tom Mainelli表示,2011年第四季度美国市场新推出的七百万的电子书阅读器中,Barnes amp; Noble占有五分之一,而Kindle的生产商亚马逊囊括了四分之三(见图)。但是Barnes amp; Noble只在美国销售Nook,这也解释了为什么它只拥有14%全球市场。通过Nook应用,其他国家的居民也可以浏览Barnes amp; Noble的电子产品目录。Microsoft is in effect buying a second bash at a market where it made an early but unsuccessful start. It launched its own e-er software all of 12 years ago. The deal with Barnes amp; Noble, bringing lots of content with it, may give people an extra reason to buy Windows 8 tablets (a likelier choice for e-ing than smartphones, laptops or desktops) when they appear.实际上这是微软在早期打入电纸书市场失败后的第二次尝试。12年前,微软就曾发布过自己的电纸书软件。这次与 Barnes amp; Noble的协议又加入了诸多内容,这使得上市后购买WIN 8平板电脑的人们多了一个理由(就电子阅读来说平板电脑是比智能手机,笔记本或台式机更好的选择)。The bundling of Barnes amp; Nobles college business into NewCo indicates a hope that a fair few of these customers will be students. Allen Weiner of Gartner , another research firm, suggests that through campus bookshops Barnes amp; Noble could sell Windows devices pre-loaded with course material. Of course, others are after students dollars too. Apple recently started selling interactive digital textbooks for the iPad, far and away the biggest-selling tablet (among its publishing partners is Pearson, part-owner of The Economist). But Mr Weiner points out that Microsoft and Barnes amp; Noble have some advantages. Lots of students write notes and essays with Microsofts Office software, which is not available on the iPad. And although Amazon sells and rents a lot of paper textbooks, it has not done much with digital ones.Barnes amp; Noble的大量高校业务融入NewCo,这意味着多数客户有望是学生。调查机构高德纳公司的Allen Weiner暗示通过校园书店,Barnes amp; Noble可以销售预先装有课程材料的Windous设备。当然其他公司也对大学生市场虎视眈眈。苹果公司最近开始为其卖得最好的平板电脑ipad销售互动电子书(合作出版社之一是Pearson,也是经济学人的股东之一)。但是Weiner指出微软和Barnes amp; Noble有优势,许多学生使用微软的office软件做笔记,写文章,而ipad上却没有这一软件。而且尽管亚马逊销售出租大量纸质教材,却并没有过多涉及电子版教材。The tie-up with Barnes amp; Noble makes three of a kind for Microsoft: cheap deals with struggling but established partners in markets where it is weak and sees a chance to do much better. In it struck an agreement with Yahoo! in online search. Last year Nokia became the prime conduit for Windows in smartphones. With Barnes amp; Noble it is having another stab at e-ing. Unlike the books on the Nook, this tale is still being written.与Barnes amp; Noble公司的合作关系是微软完成了第三项同类合作:在表现不佳有大量上升空间市场里以廉价的合同和经营不佳但在业内已树起口碑的公司签约合作。年,微软与雅虎就网上搜索达成协议。去年,诺基亚成为windows智能手机的最佳渠道。而与Barnes amp; Noble合作,则可以打入电子阅读市场。不像Nook上的电子书那样,这个故事依旧在继续。 /201301/220218

Samba and churro both started out as the homegrown musical styles of the black workers and migrants who’d moved to Rio.桑巴和奇诺都是作为搬到里约热内卢的黑人工人和移民的本土风格音乐。The songs of the early Samba singers dealt with the realities of everyday life in the city.早期的桑巴歌手应对的是日常生活城市中的现实。In the early days, musicians faced not only prejudice but harassment.在早期,音乐家面临的不仅是偏见而且还有骚扰。In 1928, the first so-called “Samba School” opened in Rio, the club where musicians and composers could meet, rehearse and plan their activities for the city’s annual pre-Lent carnival, though the authorities banned blackand mix-race carnival groups from parading through downtown, predominantly white Rio.1928年,第一家所谓的“桑巴学校”在里约热内卢开放,尽管当局禁止狂欢嘉年华团体以白人为主的混合种族在市中心游行,然而在这家俱乐部里音乐家和作曲家可以为城市的年度嘉年华会面,排练和计划他们的活动。注:听力文本来源于普特 201212/217942

  

  Business商业Energy Transfer bids for SunocoETP竞购SunocoPut that in your pipe纳入油管中A pipeline deal to exploit Americas fast-changing energy landscape美国能源局势快速多变,一桩油气管道交易抓住了契机NODDING donkeys, offshore platforms, refineries and filling stations are the bits of the oil industry you can see. A vast and largely invisible network of underground pipes joins them all together. It is worth a lot, which is why Energy Transfer Partners (ETP) said it would pay .3 billion for Sunoco on April 30th. It hopes to pull together two networks and shift more of Americas booming oil and gas output.抽油机,海上钻井平台,炼油厂还有加油站,你看见的这些只是石油工业的冰山一角。把它们连在一起的是一个庞大且几乎隐形的地下管网。它价值不菲,正因如此 ETP 公司于4月30日表示,愿意出价53亿美元收购 Sunoco 公司。美国国内的石油和天然气产量正快速增长,ETP 希望通过合并两家公司的管网,以输送更多油气产品。ETP is ambitious. Last year its parent company, Energy Transfer Equity, agreed to buy Southern Union and its gas-pipeline network for .7 billion.The latest deal will make ETP the countrys second-biggest pipeline firm, behind Kinder Morgan, after the latters merger with El Paso is concluded later this year.ETP 公司踌躇满志。去年其母公司 ETE 同意出价57亿美元,收购 Southern Union 公司及其天然气管网。最新的收购将使ETP成为全美第二大油气管道公司。Kinder Morgan 公司并购 El Paso 之后排名第一,其交易今年晚些时候完成。Sunoco comes with storage facilities, 4,900 filling stations and the remains of a refining business that it is trying to spin off in a joint venture with Carlyle, a private-equity firm. But the pipelines are the main attraction. ETP currently operates 17,500 miles (28,160km) of the arteries that transport gas and natural-gas liquids such as propane and butane. Adding Sunocos 6,000 miles, built to carry crude oil and refined products, will reduce ETPs reliance on gas. After the deal, 30% of its revenues will come from oil.收购带来了 Sunoco 公司的储油设施、4900个加油站以及一家炼油厂的剩余资产。Sunoco 打算把这些剩余资产剥离出来投入一家合资公司,该合资公司由ETP和私募股权公司Carlyle共同投资。但最诱人的部分是油气管道。ETP目前运营的油气管道干线达17500英里(约28160公里)。这些干线用于输送天然气以及丙烷、丁烷等液化天然气。加上 Sunoco 运输原油和精炼产品的6000英里管道,ETP对天然气输送业务的依赖程度将降低。交易完成后,ETP 30%的收入将来自石油输送业务。This is important. In a few years shale gass share of Americas total gas output has gone from almost nothing to around a fifth. It will account for much more in the years to come. This changes the logistics of energy delivery, says Ronald J. Barone of UBS, a bank. Shale gas is much more widely distributed than the conventional sort. It is also more scattered than the ports through which imported gas arrives.这一点意义重大。近年来,在美国天然气总产量中,页岩气的比例几乎从零上升至五分之一。今后几年,这一比例将进一步提高。瑞士联合的 Ronald J. Barone 认为,能源运输的物流方式由此改变。与传统天然气相比,页岩气的分布更广泛。与进口天然气的港口位置相比,页岩气的分布也更普遍。The more shale gas America uses, the more local the energy business becomes. Deliveries from gas basins in the south-west to the markets of the heavily populated Atlantic seaboard in the north-east are dwindling. The development of the Marcellus shale is displacing long-distance supplies with gas from Pennsylvania, Ohio and West Virginia.页岩气用得越多,美国的能源业务就越趋本地化。从西南天然气盆地到东北严重污染的大西洋沿岸,天然气输送量正在缩减。Marcellus 页岩气的开发利用开始取代宾夕法尼亚、俄亥俄以及西弗吉尼亚的远距离天然气供应。Transporting gas still brings big and stable revenues. But diversifying into oil makes sense too. Americas oil pipelines are largely unfettered by the rigid regulations that govern gas-pipeline tariffs. So transporting gloopy oil is far more profitable than shifting lighter-than-air gas.天然气运输带来的收入仍然丰厚,而且稳定。但业务扩展到输油领域也很有意义。在美国,输气管道要缴纳的关税被法规严格规定,而输油管道几乎没有这种束缚。因此,与输送比空气还轻的天然气相比,输送粘稠的石油收益要高得多。And the oil business is looking peachy. A barrel of West Texas Intermediate fetches around 0, even as gas prices recently hit a ten-year low. This has encouraged gas producers to scurry after oil in liquid-rich shale beds such as the Bakken in North Dakota. To do this, they use the same rigs and techniques, such as fracking and horizontal drilling, as they use for gas. Within a few years the Bakken and other shale beds could be producing up to 3m barrels of oil a day, reckon optimists. That is around a third of current imports.原油业务看起来也相当不错。尽管最近天然气的价格跌至十年来的低点,每桶WTI 原油价格仍在100美元上下徘徊。受此刺激,天然气生产商急忙去含油丰富的页岩层里寻找石油,如北达科他的贝根页岩层。他们用同样的钻井和技术,如水力压裂和水平钻井去找油。乐观估计,几年内贝根及其他页岩层的产能将升至日产三百万桶原油。这相当于目前原油进口量的三分之一。Owning the pipes that make all this possible should be lucrative. America has long failed to invest in pipes, since investors assumed that the country would continue to rely on imports. So there is too little capacity in many places where it is now needed. And American buyers are clamouring for more oil from Canada, which will also need pipes. Targets like Sunoco are rare. ETP was wise to swoop on it.拥有油气管道使所有这些想法成为可能,并有利可图。由于投资者认为美国将持续依赖进口石油,长期以来都未在油气管道上进行投资。因此许多地方几乎没有油气输送能力,而现在需要管道。美国买家也在呼吁增加加拿大石油的进口量,这同样也需要管道。Sunoco 这种收购对象少之又少,ETP一举拿下可谓明智。 /201210/203038。

  

  Why Is It So Difficult To Spot A Plane In The Air?为什么定位空中的飞机如此难?How many times have you heard a jet plane going over, looked up to see it, but not been able to find it even though you were looking toward where the sound was coming from? Well, this moment of science is going to tell you why you couldnt find it?有多少次你听到一架喷气式飞机飞过,抬起头去看它,即使你朝着声音传来的地方望去,却仍然无法找到它?那么这次科学时刻将会告诉你为什么你找不到它。Sometime during your life you might have been told that the plane wasnt with the sound because it was traveling faster than the speed of sound. It might have been, but it didnt have to be going that fast in order to appear to be separated from the sound.在你生活中的某个时候,你可能被告知看到的飞机和听到的声音是不在同时出现的,这是因为光的传播速度比声音快。它可能是这样的,但它没有必要为了同声音分离而飞的那么快。The reason the jet appeared to be apart from the noise it was making was simply that sound travels a lot more slowly than light–about a million times more slowly. For quick review, at sea level sound travels about seven-hundred-fifty miles per hour, light travels at 186,000 miles per second.喷气式飞机之所以和它产生的噪音相分离,是因为声音传播速度比光速慢一百万倍。简单回顾一下,在海平面上,声音的传播速度大约是每小时750英里,而光速则是每秒186,000英里。Commercial jets normally fly at about thirty-thousand feet. From that height it takes sound about thirty seconds to reach earth. Light gets here in only about four one-hundred-thousandths of a second, or for practical purposes,instantaneously.商用喷气式飞机一般在30,000英尺的高空飞行。从那个高度,声音传送到地面需要30秒的时间,而光到达地面仅仅需要4/100,000秒,实际上就是瞬间到达。A plane travelling at six-hundred miles an hour goes five miles in the thirty seconds it takes for the sound to reach you. By the time the sound from the plane reaches your ears, the plane is five miles from where that sound originated. So, when you look toward the sound, the plane is not there anymore.一架每小时飞行600英里的飞机在30秒中飞行了5英里,而声音传到你所在的地方需要30秒。在这30秒的时间里,声音从飞机传到你的耳朵里,而飞机离声音发出的地方已经有了5英里的距离。所以,当你朝声音发出的地方望去的时候,飞机早已不在那里了 /201207/190501

  

  Business The economics of Groupon The dismal scoop on Groupon商业 团购网的经济学 团购网站惨淡的独家新闻A micro-economist assesses Groupon微观经济学家评估团购网站GrouponON OCTOBER 24th Groupon says it will start its ;roadshow;.Groupon声称将于10月24日开始;路演;。The social-media sensation, which offers online coupons for bargains at local shops and restaurants, is planning an initial public offering later this year.这个曾一时轰动的社交媒体,提供当地商店和餐馆特价商品的在线优惠券,计划今年晚些时候进行首次公开招股(IPO)。Valuations as high as billion were until recently bandied around, but that now seems wildly optimistic.直到最近才有消息称该公司市值高达200亿美元,但是现在看起来有点过于乐观,Groupon will lose 0m on revenues of .69 billion in 2011, predicts Benchmark, a consultancy. That is an ocean of red ink.邦仕马克(Benchmark)咨询公司预测Groupon公司2011将亏损2.8亿美元,年收入为16.9亿美元。这是巨大的亏损。Groupon started with a nifty idea. Its website offered a ;daily deal; whereby consumers could buy a product or service very cheaply if a minimum number of people signed up.Groupon公司源于一个奇妙的想法。该网站提供一个;每日交易;,如果购买的人数达到最低要求,那么消费者可以非常便宜地购买一件商品或一项务。People would nag their friends to come to the same bar or shop. The merchant would get new customers. Groupon would take a cut.人们就会要求他们的朋友去相同的酒吧或商店,商店就会有新的消费者,Groupon也从中分一杯羹。For merchants, this model has big advantages.这种模式对于商店来说有巨大的优势。They are advertised on Groupons phenomenally popular website. This is especially useful for new businesses that no one has heard of.他们在Groupon表面上受到大众欢迎的网站上刊登广告,这对无人知晓的新商业来说特别有用。Groupon helps merchants manage capacity, too.Groupon公司也帮助商家控制数量。For example, a restaurant might sell vouchers that are redeemable only on Tuesdays, thus filling tables on a quiet night.比方说,某餐馆出售的抵用券只能在星期二使用,这样就能使原本生意冷清的周二晚上爆满。Or a Pilates studio might use vouchers to manage class sizes.或者某个普拉提健身房通过使用抵用券控制课程人数多少。Once a client has paid for the voucher, the studio collects the fee even if she is hung-over and doesnt turn up.一旦客户付抵用券,即使客户延迟且不来参加普拉提课程,健身房也会收到这笔费用。Groupon also allows merchants to charge different people different prices for the same product.Groupon同样允许商家在出售同样商品时,对不同客户收取不同的费用。A student might buy theatre tickets on Groupon for half price. A businessman with no time to shop around online might buy the same tickets for full price.学生可以在Groupon网站上以半价购买电影票,而没有时间在网上闲逛的商务人士可能以全价购买相同的电影票。Without Groupon, it is harder for the theatre to find out what people are willing to pay.如果没有Groupon的话,电影院很难发现什么样的人原意付。It could charge both punters full price, in which case the student may stay at home.如果都是收取全价的话,那么学生就会待在家里不去看电影了;Or it could charge both the lower price, in which case it makes less money.如果都是收取半价的话,那样电影院赚的就少了。Groupon created a new market.Groupon创造了一个新的市场。This is a boon to consumers, but confers no lasting ;first-mover; advantage on Groupon.这对消费者来说是福利,但是对于Groupon来说并没有持续;先发制人;的优势。Its business model is unpatentable and simple to replicate, so there are aly more than 20 copycats.Groupon的商业模式没有获得专利,而且模仿起来很简单,因此已经出现超过20个模范者。Groupon aspires to be global, but the markets it serves are intensely local.Groupon渴望全球化,但是它务的市场却非常本地化。Internet selling is best suited to ;experience goods;.网络营销最适合;已经体验过的商品;。These are goods and services the quality of which you cannot judge until you experience them, such as haircuts and Thai meals, so there is no advantage in having a bricks-and-mortar shop for people to browse in. (In North America 83% of Groupons deals fall into this category.)这些商品和务的质量只有在你购买之后你才能判断,比如理发、泰国食物,因此,如果网站上供人浏览的只有传统实体企业,那么毫无优势可言(Groupon在北美83%的交易都是这些类别)。The trouble with experience goods is that generally you cannot separate manufacture from delivery: you cannot cook a meal in Guangzhou and eat it in New York.大家体验过的商品存在一个问题,那就是通常你无法将生产与运输分开:你不可能在广州烹调,然后在纽约享用。So for Groupon, each city is a separate market. (Big ones, such as London, are subdivided into regions.)因此,对于Groupon来说,每个城市都是一个独立的市场(诸如伦敦这样的大城市又划分为区域)。In each neighbourhood, it must vie with copycats to sign up merchants. Its marketing costs are expected to be a painful 8m this year. This is why it loses money.在每个街区,Groupon都要与模仿者竞争登记商家。Groupon的营销成本将会达到9.58亿美元,这正是其亏本的原因。A final woe: the Groupon model is open to abuse.最后的悲哀就是,这种模式公开被滥用。Nicole Peters, an avid online shopper, describes how she bought a massage via one of Groupons rivals.网上购物狂妮可?彼得斯(Nicole Peters)描述她是如何从Groupon竞争对手哪里购买一项务的。The day before the appointment, the massage firm e-mailed her to say it had gone bust.在预约日的前一天,公司发邮件给她说公司破产了。Ms Peters also bought a voucher for several pairs of mens underpants. When she logged onto the suppliers website, there were only huge pairs or bright pink ones available.彼得斯女士还购买了几条男士内裤的兑换券,当她登录供应商的网站时,只有大号的裤子和明亮粉红的裤子。She says she will never shop this way again.她说,她以后再也不会通过这种方式购物了。Groupons webpage includes a guide to avoiding arguments with merchants, which suggests such tiffs are common.Groupon的网页中包括如何避免与商家扯皮的指南,这就意味着这样的口角事件很常见。In short, Groupon is still the king of online discounts.总之,Groupon仍然是网购折扣的领军者。But with so many pretenders around, it may be unwise to pay a premium for its shares.但是随着模仿者的异军突起,为了购买其股票而付佣金就显得不明智了。On October 19th the firm was reportedly considering scaling back its IPO.据报道,10月19日,Groupon考虑相应缩减首次公开募股的规模。 /201212/216129

  Saturn’s apparently peaceful appearance is due to a haze of high level ammonia in the upper atmosphere,土星明显和平的外表是由于在大气层的上方朦胧的高浓度氨所致,by looking deep into Saturn in the infrared, using the planet’s own internal heat as a light source,通过用红外线深入地观察土星,利用星球的内部热量作为光源,Cassini has revealed the planet’s true nature.卡西尼号已经揭示了这颗星球的真实性质。The winds on Saturn vary dramatically from the equator to the pole and in fact, at the equator we have huge winds,土星上不同的风剧烈地从赤道到北极,事实上,在赤道附近我们有非常强烈的风势,we’re getting close to 900 miles an hour now, and get a speed of sound in that planet.我们越来越接近每小时900英里,现在已经得到在这颗行星一种声音的速度。The winds are stronger at Saturn than they’re in Jupiter, and that’s a surprise,土星的风比在木星要强烈,这是一个惊喜,because the two planets are rather similar in terms of basic composition,因为这两个行星在基本成分上相当类似,they’re both gas giants and yet Saturn has less sunlight to power the winds, and winds are stronger.他们都是气体巨星,但土星较少的阳光可以影响风势,所以风力更强劲。Try explaining the 6-sided vortex at the North Pole.试着解释在北极的六面漩涡。Saturn has a hexagon, it’s some kind of a wave, but it’s a permanent wave.土星有一个六边形,它是一种波,但这是一个永久的波。It’s been there since voyager discovered it back in 1980.自1980年“航行者”号发现它后已经一直存在。So this is just one more example of how atmosphere features which are basically nothing but gas.所以这只是一个例子,大气特征基本上除了气体没有什么。They last forever on these giant planets.它们将永远在这些巨大的行星上持续。注:听力文本来源于普特201206/186013。

  

  When Europes been peppered with uncertainty the whole year. And Monti was always a technocratic government that came in with a specific mandate. Then of course, Italys a democracy, said you will step aside and theres an election. Could come back as a politician. Maybe not. I think the fear is who could replace him. But I think hes done an excellent job and hes steadied the ship. But he did say he would step aside after a year, done certain measures.今年一整年内欧洲经济充满不确定性因素。蒙蒂政府是临危受难,肩负特殊使命的技术专家政府。当然,意大利是一个民主国家,蒙蒂即将辞职,将进行新的一轮选举。这一次可能是由政治家来担当此重任吗?可能不会。我想,人们担心的是,谁能够取代蒙蒂?因为我认为,他的工作非常出色,稳定了局势。但是他曾说过,在采取了一定措施后的一年后他要辞职。Now heres the question. Is it the issue of Monti stepping aside when he was sort of the steady hand on Italys unsteady finances, if you like? Or is it respective Berlusconi coming back that really has people worried? Because the bond markets, we see the yield rising on the 10-year Italian bonds as it seems that stock markets plummet in Milan.现在的问题是,蒙蒂目前已成为意大利不稳定财政的坚定领导人时,他真的要退出政府吗,你希望这样吗?或者,人们真正担心的是贝卢斯科尼再次掌权。因为,虽然债券市场的10年长期意大利国债收益正在增加,米兰的股票市场看起来却在大幅下跌。Yes, but its a one-day wonder that you saw the euro come off this morning, bounced right back. These markets are incredibly volatile and theres not much to do. So people are obviously to sell the story. Yes, of course, theres a few of them may replace him. Technocratic government did what the markets liked, gave us certainty but as I said, this is a democracy and democracies create uncertainty. And so wholl replace him? We dont know. But I think this big story moves on to Spain, the ESM and whether the ECBs going to start printing or not.是的,但是这只是一天的奇迹,今早欧元开始好转,有所反弹。毫无疑问,市场是易变波动的,有时候,人们有心无力。因此,人们很容易被说,是的,当然能取代蒙蒂的人不多。技术型政府可以采取任何市场喜欢的措施,给我们带来确定性。但是,如我已经说过的,这是一个民主国家,民主就会产生不确定性。因此,对于,谁能取代蒙蒂,无人所知。但是,我认为,现在欧洲现在的大问题已经转移到了西班牙,额外西班牙货币以及欧洲中央是否启动印制?OK. Now thats an interesting one. 2013 looming as I was saying before. Does that mean were going to have a full-on Spanish bailout in the early months of next year?是的。是让人感兴趣的问题。2013将至,这是否意味着,明年的最初几个月,将进行西班牙全面救市?I think could come even late this year. I think if it wasnt for the fiscal cliff and the market changing its focus over tension onto the US, we would have pressurized aly Spain into coming to the ESM, which as you know, ESM stands for Extra Spanish Money. So it shouldnt be a surprise when they confirm.我想可以要到明年晚些时候。我认为,如果不是到财政悬崖,以及市场将压力焦点转向美国,我们不会迫于压力,让西班牙采用额外西班牙货币,你知道,ESM的意思。如果此事得以确定,也在意料之中。Rather the European stability.只要欧元区能够稳定。Yes, absolutely.是的,绝对如此。Might even have gotten lost in the alphabet soup aly that EU’s created to try and solve the eurozone crisis. Well, what about credit rating cuts for some of these countries, notably just going back to the issue of Italy and the face of so much uncertainty? This is going to make it very difficult for these countries to try to cut their enormous amount of debt of debt-to-GDP, cut their budgets. And if they do get downgraded, will their debt becomes more expensive.也许问题都能够在这一缩写词语中得到解决,欧盟创造该词语以试图解决欧元区危机。不过,这几个国家的信用评级下调情况如何?特别是,刚才谈到的意大利问题,我们又如何面对这么多不确定性?这些国家试图减少债务率(债务占国内生产总值的比重)债务以及减少预算,都将变得非常艰难。如果他们的信用评级下调,那么他们的债务将变得格外昂贵。Well, not in the case weve seen of France. They got downgraded with, again, a one-day wonder. They sold off and French yields are straight back down again. The problem is if your debt-to-GDP starts rising but you think austeritys the answer, and you do austerity but growth starts to plummet, then you need more austerity and then growth goes down. And thats the Greek situation we’ve got ourselves in for. So Id say just ignore the rating agencies and try to do the right thing. Get growth going and dont overdo the austerity.是的,不过我们看到法国的情况例外。法国被降级了,不过这也是一天之内的奇迹。他们的股票低价抛光,法国再次收回了收益。问题在于,如果债务率开始上升,但是你却认为只有采取紧缩政策,并且你实施了紧缩政策,但是增长急剧下降,于是,你需要采取更多的紧缩,增长继续衰减。这就是我们让自己陷入希腊危机的原因所在。因此,我宁愿大家暂时忽略评级机构,而专注于做正确的事情:让经济增长,不要过于倚重紧缩政策。 201212/217889

  The tool you and I would call was daydreaming, but he gets it called thought experiment because he is Einstein.你和我管它叫白日梦,但是他就是称它为思想实验,因为他是爱因斯坦。In his office, the patent office, looking out of window and he imagined a man working on a roof.在他专利局的办公室里,他从窗口望去,他想象着在屋顶工作的一个人。And he begins to wonder what would happen if one of those men would fall off the roof.他开始想像如果其中一个男人会从屋顶上跌下来的情境。And then he had the happiest thought of his life, the inspiration of the ages.然后他有了的人生中最快乐的思想, 年龄的灵感。He had a vision the man would not actually be feeling his own weight.他曾经想那人不会感到自己的体重。He will be weightless. And then he imagined if you are in an elevator and somebody cuts the cord.他将是无重的。然后他想象如果是在电梯里,有人剪断绳索的情境。What happens to you?你会发生什么?You fall but the elevator falls at the same rate you do, so you are weightless inside the elevator. So then Einstein got it.你在下坠但电梯和你的速率是相同的,所以你处于失重而爱因斯坦有了结论。Its though the gravity has been switched off. Whats really going on?虽然引力已经关闭。这究竟是怎么一回事?The reason is no such a thing as gravitational pull.原因是没有所谓的引力。The earth has curved the space around me and space is pushing me into this chair. Space itself can be curved.在我身边的是地球弯曲的空间,空间推动我到这把椅子上。空间本身是可以弯曲的。注:听力文本来源于普特201203/176192

  • 当当分类佛山治早泄那家医院好
  • 佛山人民医院不孕不育科
  • 佛山市顺德区均安医院治疗阳痿早泄度中文
  • 时空互动佛山最好的割包皮医院
  • 豆瓣新闻顺德区妇幼保健院男科专家
  • 佛山市第四人民医院包皮手术多少钱
  • 顺德区伦教治疗前列腺疾病哪家医院最好医苑分享
  • 当当常识佛山新世纪看男科怎么样
  • 佛山市南海区里水医院包皮手术怎么样
  • 佛山医院看男科怎么样天涯优惠
  • 三水中医院男科咨询
  • 城市信息佛山割包皮过长的医院
  • 顺德区新世纪医院正规吗康泰资讯佛山包皮包茎过长手术费用
  • 佛山男科医院尿科
  • 佛山哪家医院治疗男科最好
  • 佛山市顺德区均安医院男科专家挂号
  • 咨询对话佛山医院网上预约系统
  • 顺德区乐从医院医院男科
  • 佛山市南海区里水医院治疗前列腺炎多少钱
  • 勒流医院在哪里
  • 祖庙石湾张槎桂城街道看前列腺炎好吗
  • 好养生佛山市妇幼保健院看前列腺炎好吗
  • 最新优惠广东省佛山新世纪医院男科挂号豆瓣诊疗
  • 顺德新世纪不孕不育收费好不好大河活动佛山看不孕不育有那些医院
  • 58健康佛山看男科找哪家医院快乐网
  • 佛山人民医院是几甲
  • 佛山市中医院男科咨询
  • 佛山医院做包皮手术多少钱
  • 顺德中医院在哪
  • 南方医科大学顺德医院不孕不育收费好不好
  • 相关阅读
  • 佛山市顺德区中医院在哪
  • 泡泡生活顺德区勒流医院要预约吗
  • 佛山治疗阳痿早泄
  • 百科分享佛山一院泌尿外科
  • 三水人民医院泌尿科咨询58诊疗
  • 佛山人民医院男科医院
  • 预约专家佛山新世纪医院看泌尿科怎么样
  • 三水区妇幼保健院泌尿科咨询
  • 佛山哪个医院治疗尖锐湿疣最权威
  • 百姓中文顺德区中医院治疗前列腺疾病多少钱新华社区
  • 责任编辑:光明热点

    相关搜索

      为您推荐