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2020年01月25日 07:55:05来源:家庭医生优惠

  • Bringing The Dead Back To Life? Is it possible to bring the dead back to life? Maybe not, but scientists at Penn State University have done the next best thing. They found a tiny bacterium thats been trapped miles below Greenland ice sheets for the past 120,000 years.起死回生?有可能起死回生吗?也许不能,但宾夕法尼亚州立大学的科学家做了差不多的事情。他们在格陵兰岛冰原的地下几十英里处发现了一种12万年以前的极小细菌。After months of incubation, the bacterium woke up and began reproducing. Before long, the ancient organism was once again thriving. Now dont be alarmed. Unlike what may happen in a science fiction thriller, the bacterium isnt some deadly microbe thats going to turn us all into zombies.经过了数月的培育,细胞已经复苏并开始繁殖。很快,古生物再次繁荣起来。现在不要惊慌。与科幻惊悚片里场景可不一样,这些细菌并不是那种会把我们变成僵尸的致命细菌。Apparently, its a very small, simple microbe not very different from billions of others that have lived on earth. Whats interesting about the microbe is: A) how it managed to survive for so long beneath the ice; and B) what it suggests about the possibility of life on other planets.显然,这是种非常微小,简单的生物,它与地球上其它数十亿的细菌并无太大区别。这种微生物的有趣之处在于:首先,它如何能在久冰层下面存活那么久;其次,它的存在表明其他星球上可能存在生命。The researchers think that the bacteriums small size might have helped it survive in microscopic, watery veins in ice crystals. Being small may also have helped the microbe absorb nutrients more efficiently.研究人员认为,这种细菌能够存活在冰晶纹理的潮湿细缝里可能是由于它体积微小的缘故。体积小可能也会帮助微生物更充分地吸收营养物质。As for life on other planets, scientists have long suspected that if there is life out there, it might exist buried far beneath a planets barren surface. So every time scientists find a microbe able to survive under extreme conditions on Earth, it raises the hope that the same might be the case in other worlds.至于其他星球上是否存在生命,科学家们早就抱有怀疑:如果外太空有生命存在,那么它可能深埋在某个星球贫瘠的表层下。因此,每当科学家们发现新出现一种微生物能在极端的地球环境下生存,那么在其他星球上出现同样情况的可能性就更大。201212/216649。
  • Science and Technology科学技术Palaeontology古生物学Splay-footed, not flat-footed八字足,而非平足A new fossil shows that evolution does not always mean change一个新的化石表明:进化并不总是意味着改变Then and now过去与现在WHEN a coelacanth, a type of lobe-finned fish once considered the missing link between fish and amphibians, was found off the coast of South Africa in 1938, it came as a shock to palaeontologists.以前人们一度认为一种叫做腔棘鱼的鳍鱼是鱼类和两栖类之间缺少的环节,1938年当腔棘鱼在南非海岸沿海被发现时,古生物学家对它的出现大感震惊。Until then, the most recent traces of such a creature had been in rocks dating from the last days of the dinosaurs, 65m years ago.在此之前,这种动物最近的遗迹出现在6500万年前恐龙时代后期的岩层中。It was, in its way, as surprising as if a live Tyrannosaurus had been found hiding in an obscure part of Montana.而它这次的出现方式,就好像一个活生生的霸王龙属被发现藏身在蒙大拿州的模糊地带一样令人惊讶。Now the same experience is hitting palaeontologists again—but this time in reverse. Instead of finding a living fossil identical to an ancient beast, they have found a real fossil identical to a modern one.现在,同样的经历再次让古生物学家碰上了,不过这次相反。他们不是找到了一个与古兽相同的活化石”,而是找到了一个跟现代兽类相同的真正化石。The fossil in question, a 100m-year-old specimen from north-east Brazil, belongs to the genus Schizodactylus.所讨论的的化石采自巴西东北部,是一亿年前的标本,属于节肢动物类。These are large, carnivorous, cricket-like insects whose feet splay out wildly in different directions.这类节肢动物是大型类似板球的食肉昆虫,其足向不同方向伸展开来。Modern Schizodactylus use their feet like snowshoes, to help them remain stable as they travel over sandy terrain in search of prey.现代节肢动物在沙地爬行寻找猎物时用它们雪鞋般的脚来帮助身体保持稳定。If the new fossil—whose discovery has just been published in ZooKeys by Sam Heads of the Illinois Natural History Survey and Léa Leuzinger of the University of Fribourg, in Switzerland—were merely similar to modern splay-footed insects, the find would not be particularly surprising:如果新化石其发现刚由伊利诺斯州自然史调查的负责人山姆和瑞士弗里堡大学的李?劳伊辛格发表在《动物图谱》上仅是类似现代的八字足昆虫,那么这个发现不会特别令人惊讶:it simply demonstrates a phenomenon called evolutionary stasis, in which a specific type of body form hangs around for a long time.它只是明了一种被称为进化停滞的现象,在这种现象中特定类型的体型存留很长一段时间了。What is surprising is just how static Schizodactylus has been.令人惊讶的是节肢动物停止进化竟有这么久了。Evolutionary stasis is fairly common at the higher levels of the Linnaean system of biological classification.在林耐生物分类系统的高等类别中进化停滞现象是相当普遍的。Natural selection hits on a good design.自然选择的图案都是最好的。That design is then adopted in slightly different forms by species after species.然后,这种图案就被一个接一个的物种以略有不同的形式所采纳。The shelled bodies of turtles, for example, evolved between 250m and 200m years ago, while the body plans of scorpions have been around for more than 400m years.例如,海龟的壳体是在2.5~2.0亿年前进化的,而蝎子的体型方案已超过4亿年的历史。That does not mean, however, that a zoologist would mistake a 200m-year-old turtle or a 400m-year-old scorpion for any species now alive.然而这并不意味着一个动物学家会弄错2亿岁的海龟或是4亿岁的蝎子属于现在存活的何种物种。What is remarkable about the new find is that it is so similar to modern animals that it can be assigned to an existing genus—the lowest level of Linnaean classification above a species—rather than just to some higher taxonomic group.新发现引人注目的是它与现代动物如此相似,以致它可以被列入现有生物分类种类,而不是只被列入某一更高等的分类组。That is rare indeed.这的确罕见。Even the modern coelacanth, on closer examination, had to be put in a different genus from any known fossil.经过仔细观察,甚至就连现代腔棘鱼都必须得归类于不同于任何已知化石的种类。Clearly the body plan of Schizodactylus is not merely good, but optimal, at least for the environment the animal lives in.显然,节肢动物的体型方案不仅是最好的,也是最佳的,至少对这种动物生活的环境而言是如此。Alas for Schizodactylus, the sandy deserts it prefers have retreated from north-eastern Brazil and its optimality there has vanished.唉,对节肢动物来说,它所喜爱的沙质沙漠已经从巴西东北部退却,它在那里的最佳体态已经消失。But its discovery shows better what this part of the world was like 100m years ago—and also illustrates an important point about evolution that is often forgotten in biologists understandable focus on the development of novelty. The first rule of natural selection is: If it aint broke, dont fix it.”但它的发现恰好说明这部分的大千世界跟1亿年前的样子很象,也说明了进化论的一个重点,而这点在生物学家关注理解新颖性的发展时往往被遗忘了。自然选择的第一条规则是:如果没坏,就不要修理它。” 点击此处下载本期经济学人讲解PDF与音频字幕 /201303/228974。
  • Ironically, to possibly revive some form of life on Mars, we need to introduce the same conditions that are threatening life here on earth. To establish human societies on Mars with significant industrial capacity. They could create these green house gases there. Warm the planet, it would cause the water thats frozen into soil to start melting out, running again in the streams and riverbeds of Mars filling the lakes and putting water vapour into the atmosphere. And water vapour is green house gas.讽刺的是,为了使火星重燃生命,我们需要引进一些条件,而这些条件在地球上却会威胁生命。为了利用强大的工业生产力在火星上建立人类社会,可能会在这里产生温室气体,从而将火星变暖。火星变暖就会导致冻在土里的冰层融化成水,重新汇聚成河流在火星上流淌,然后填满湖泊,将水蒸发到大气中。水蒸气就相当于温室气体。Mars would have an environment suitable for life, suitable for plants, trees, grasses insects. But before we can export cars, factories and other polluters to Mars, we need to get there and it wont be easy. We go to Mars, we are constrained by the position of the planets around the Sun. The Mars is our nearest neighbor. Its still very far away. At their closest, the earth and Mars are over 34 million miles from one another. And since the two planets move in different orbits at different speeds they are usually even further apart. A manned voyage to Mars will have to be time just right. The window of opportunity to go from earth to Mars or from Mars to earth opens up only once every two years.火星上应该有适合生命存在的环境,适于植物,树木,草和昆虫生长的环境。但是在我们引进汽车,工厂还有其它污染源前,我们需要确保安全抵达火星,这并不容易。我们要去火星,但我们被局限在环绕太阳公转的行星上。火星是我们最近的邻居,但仍然很遥远。即使靠的最近,但火星和地球之间的距离仍有3千4百万英里。因为这两个行星分别以不同的速度在不同的轨道上公转,他们经常会越离越远。人类登陆火星的时机需要把握准确。从火星到地球或者从地球到火星的最佳时机每两年才出现一次。So a trip to mars might involve taking six months to get there, and then staying on Mars for two years. Part of preparing to sent humans tomorrows is to test our equipment and procedures here on earth.因此一次火星之旅需要花六个月时间在路上,然后还需在火星上呆2年。送人类上火星的部分准备工作是在地球上测试设备和程序。Its safe to say that one day soon we will go to Mars. If you wanna be among the first humans to go, the time to prepare yourself is now, which is exactly what the Mars Society is doing.可以很有把握的说很快我们就会去火星。如果你想成为第一批去火星的人,那么现在就得准备了,这也正是火星协会正在做的。The Mars Society is an international organization of people committed to furthering the exploration and ultimately settlement of Mars.火星协会是一个志在进一步探索火星,最终在火星上建立定居点的国际性组织。The first step to going to Mars is acting as if you are aly there.去火星的第一步:表现地就像你已经在火星上一样。 原文译文属!201208/194203。
  • Its an incredible idea. But most experts now believe that todays birds are the direct descendants of ancient dinosaurs.这是一个很不可思议的观点。但是大多数专家认为今天的鸟类是古代恐龙的直系后代。So does that mean birds actually are dinosaurs?这么说鸟类是恐龙?Yes. Absolutely.是的,当然。How can you be sure about that?你怎么如此肯定?You have evidence from the skeletal anatomy. You have evidence from the shape of the eggs and the microstructure of the eggshell, the discovery about a wealth of feathered dinosaurs, animals that are unquestionably dinosaurs and yet have feathers. They looked just like the feathers on modern birds.你能从骨骼解剖图里找到据,从卵的形状、卵壳在扫描电镜下的微观结构找到据。发现大量长有羽毛的动物,毫无疑问这种动物就是恐龙,长有羽毛的恐龙。他们看起来就像现代的鸟类。Its a discovery that revolutionizes the way we see dinosaurs. Even some tyrannosaurs were feathered. But the relationship between birds and dinosaurs can tell us much more than simply what they may have looked like.这个发现彻底改变了我们对恐龙的看法。有些霸王龙竟然也长有羽毛。鸟和恐龙的关系会为我们揭开更多奥秘,而不是仅仅展示外貌上的相似。So does this mean that we can use living birds to help us understand dinosaurs?那么这意味着我们能利用活着的鸟类帮助我们了解恐龙吗?Absolutely. You know you have 10,000 living species of birds that are providing you an enormous amount of information that you can use to understand the biology of the ancient dinosaurs.当然。你也知道世界上有10000种鸟类,这就为我们研究古代恐龙的生物学提供了大量的信息。Its quite amazing. But it also makes a certain degree of sense when really you look at them.这太令人惊奇了。但当你真正观察它们的时候,在一定程度上也合情理。If we want to learn about how the ancient dinosaurs moved and even how quickly they ran, few animals can tell us more than ostriches. They evolved on an early branch of the avian family tree. And like dinosaurs they are related to, they are large, bipedal and flightless.如果我们想要了解古代恐龙如何运动,了解他们跑得多快,那就没什么能比鸵鸟带来更多信息。鸵鸟是由早期的鸟类家族分进化而来。正如与之关系密切的恐龙一样,鸵鸟个头巨大,两足且不能飞翔。I have some living dinosaurs here to take a look at.我这儿有一些活恐龙可供观察。Hello, ladies.嗨,女士们。Theyre all ladies, are they?他们都是雌恐龙,是吗?Yes. Yes. They are a bit more manageable when they are females.是的,是的。雌恐龙才更容易控制。原文译文属!201210/203166。
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