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2019年08月23日 01:53:27来源:快问指南

Don: Holy guayule,Yale.唐:神圣的灰白银胶菊,雅艾尔。Yael: Holy what?雅艾尔:神圣的什么?Don: Guayule. Its a desert-dwelling shrub from the Southwest.唐:灰白银胶菊。它是一种生长在西南部沙漠中的灌木。Yael: What about guayule? I never even heard of it.雅艾尔:灰白银胶菊是什么样的?我从来没听过。Don: Several things. One of the most important features of the guayule plant is that it is a source of natural latex, ideal for making gloves and other natural rubber products used in the medical industry. But unlike the more common latex extracted from rubber trees, latex from guayule plants does not contain the proteins that cause severe allergic reactions in some people.唐:有几件事你应该了解一下。灰白银胶菊最重要的特点是它能分泌天然乳胶,是制造手套以及其它医疗工厂使用的橡胶制品的理想原料。但是跟常见的那些从橡胶树上提取的乳胶不同,从灰白银胶菊中提取的乳胶中没有会使人产生严重过敏反应的蛋白质。Yael: Nice.雅艾尔:不错。Don: But thats not all. Crop researchers have discovered that the guayule plant is a potentially valuable source of energy. After the latex is extracted from the plant, youre left with the ground up stems and branches—called “bagasse.” Bagasse from guayule contains about as much potential energy per pound as charcoal. USDA chemists are working to develop efficient methods to convert bagasse into ethanol and other consumer y products. Guayule has a few advantages as a source for biofuel. One is that it grows and thrives in the desert. That means it can grow in areas where other crops cant. Guayule shrubs can also be harvested year round, and require very little fertilizer or chemicals to grow. On top of that, the latex extraction process uses only water, no harsh solvents, so the process of producing latex and bagasse is relatively clean.唐:还不止这些呢。研究者们还发现银胶菊是一种很有开发前景的能源。当你把乳胶从植物里提取出来后,就会剩下一大堆银胶菊的秸秆,我们称为“甘蔗渣”。每磅甘蔗渣里含有的能量和每磅木炭一样多。美国农业部的化学家正在研发一种有效的方法,以便把这些甘蔗渣转化成乙醇和其他可供消费的产品。作为生物燃料,银胶菊有一些优势。其中一项就是他在沙漠中茁壮的生长,这就表示了它能在其他生物无法生存的环境中存活。银胶菊灌木一年就能收获吗?它全年都能收获,且只需要一点点肥料和化学药剂。除此之外,银胶菊的乳胶提取工艺只需要水就够了,不需要严格的溶剂。所以生产乳胶和甘蔗渣的过程是比较清洁的。Yael: That does sound promising. ILL look forward to hearing more about guayule in the future.雅艾尔:那听起来的确很有前途,我期望以后能多了解一些银胶菊的知识。Don: I suspect we will.唐:我猜会有机会的。201305/240321。

  • Don, why are you slouching?唐,为啥你无精打采?Dont you know its bad for you?你不知道这对你不好?Did you know that about 200 tons of debris strike the Earth every day?你知道每天大约200吨的碎片来到地球?So I was thinking!所以我在思考。Although most of this stuff burns up in the atmosphere, the resulting dust still settles and adds tothe Earths mass.虽然这些东西中的大部分在大气中烧掉了,但是烧完后的灰尘仍然沉淀并增添地球的质量。Thats about half a million tons per year!大约每年有50万吨。All right, but what does all this have to do with your posture?好的,但是所有这些与你的仪态有啥关系呢?So if the earth keeps accumulating mass, doesnt that mean that the Earths gravitational pull hasbeen increasing?所以如果地球持续累积其质量,那不是意味着地球的引力也正在增加?After all, gravity is directly proportional to mass.毕竟,引力与质量是成比例的。Are you saying you cant sit up straight because gravity is stronger now than it used to be?你说你不能笔直端坐是因为地球引力比以前更强了?Admit it, Yael;l–its a good one.承认这一点吧,这是件好事。Earths mass in metric tons is approximately six followed by twenty-one zeroes.地球的质量按照公制吨位来衡量大约是6后面加21个0。So assuming thatyour estimate is correct, and the Earth accumulates a half a million tons of debris every year.所以假设你的估计是正确的,并且每年地球积累50万吨的碎片。This means that in the sixty million years since dinosaurs existed the Earth would have accumulatedapproximately thirty trillion tons of meteoric debris.这意味着自从恐龙存在以来的6000万年,地球已经积累了大约30万亿吨的流星碎片。Thats thirteen zeroes.那是13个0。The point is that a number with thirteen zeroes is minuscule relative to a number with twenty-four zeroes.关键是13个零相对24个零而言是非常小的。While thirty trillion tons sounds impressive, it is nothing compared to the Earths total mass.虽然30万亿吨听起来很震撼,但是它与地球总的质量相比还是微不足道的。So it s definitely not all that extra gravity thats making you slouch所以很明确的是额外的重力不会使得你无精打采。 201408/321643。
  • How animals perceive time动物如何感知时间?Slo-mo mojo慢动作的魔力Small creatures with fast metabolisms see the world like an action replay小生物可能拥有快速代谢系统,眼中的世界就想慢动作回放。Sep 21st 2013 |From the print editionFLIES live shorter lives than elephants. Of that there is no doubt. But from a fly’s point of view, does its life actually seem that much shorter? This, in essence, was the question asked by Kevin Healy of Trinity College, Dublin, in a paper just published in Animal Behaviour. His answer is, possibly not.苍蝇的寿命比大象短。这是毫无疑问的。但是从苍蝇的角度来说,它的生命真的有那么短暂吗?这是都柏林圣三一学院的Kevin Healy在《动物行为》上发表的论文中提出的问题的本质所在。他的回答可能是否定的。Subjective experience of time is just that—subjective. Even individual people, who can compare notes by talking to one another, cannot know for certain that their own experience coincides with that of others. But an objective measure which probably correlates with subjective experience does exist. It is called the critical flicker-fusion frequency, or CFF, and it is the lowest frequency at which a flickering light appears to be a constant source of illumination. It measures, in other words, how fast an animal’s eyes can refresh an image and thus process information.对时间的主观经验就是主观的。即使是能与彼此交谈对照时间的人类也不能确定他们跟别人的经验相同。但是,客观的测量与主观的经验确实有关系。这就是所谓的临界闪烁融合频率,简称CFF,这是闪烁的光作为照明固定光源的最低频率。换句话说,测量动物眼睛刷新图像的速度然后处理信息。For people, the average CFF is 60 hertz (ie, 60 times a second). This is why the refresh-rate on a television screen is usually set at that value. Dogs have a CFF of 80Hz, which is probably why they do not seem to like watching television. To a dog a TV programme looks like a series of rapidly changing stills.对人类来说,平均的CFF是60赫兹(即,每秒六十次)。这是通常设置的电视屏幕刷新率。眼睛的刷新率是80赫兹,这可能是它们不看电视的原因。对来说,电视节目看起来像一系列快速变化的幻灯片。Having the highest possible CFF would carry biological advantages, because it would allow faster reaction to threats and opportunities. Flies, which have a CFF of 250Hz, are notoriously difficult to swat. A rolled up newspaper that seems to a human to be moving rapidly appears to them to be travelling through treacle.有最快速的CFF会拥有生物学优势,因为这意味着面对威胁或者机会时会有更快的反应速度。苍蝇的CFF是250赫兹,很难被拍死。在人类看来迅速落下的一卷报纸在苍蝇看来就想是慢动作。Mr Healy reasoned that the main constraints on an animal’s CFF are its size and its metabolic rate. Being small means signals have less far to travel in the brain. A high metabolic rate means more energy is available to process them. A literature search, however, showed that no one had previously looked into the question.Healy先生推断,动物CFF的主要限制来自于其体型及其新陈代谢速度。体型小意味着大脑中信号传递速度快。高代谢率意味着更多的能量处理信息。然而,一个文献检索显示之前没人研究过这个问题。Fortunately for Mr Healy, this search also showed that plenty of people had looked at CFF in lots of species for other reasons. Similarly, many other people had looked at the metabolic rates of many of the same species. And size data for species are ubiquitous. All he had to do, therefore, was correlate and repurpose these results. Which he did.幸运的是,对Healy先生来说,很多人为了别的原因也研究了许多物种的CFF。同样的,许多人也研究了许多上述物种的新陈代谢速率。物种体型大小的数据到处都是。这么一来,他需要做的就是关联并重新利用这些结果。他这么做了。To simplify matters he looked only at vertebrates—34 species of them. At the bottom end of the scale was the European eel, with a CFF of 14Hz. It was closely followed by the leatherback turtle, at 15Hz. Tuataras clocked in at 46Hz. Hammerhead sharks tied with humans, at 60Hz, and yellowfin tuna tied with dogs at 80Hz. The top spot was occupied by the golden-mantled ground squirrel, at 120Hz. And when Mr Healy plotted his accumulated CFF data against both size and metabolic rate (which are not, it must be admitted, independent variables, as small animals tend to have higher metabolic rates than large ones), he found exactly the correlations he had predicted.为了简化问题,他只看34种脊柱动物。CFF最低的是欧洲鳗鲡,只有14赫兹。紧随其后的是棱皮龟,有15赫兹。锤头鲨跟人类一样,是60赫兹,黄鳍金鱼跟一样是80赫兹。最高的是地鼠,有120赫兹。当Healy先生将他的CFF数据跟体型和新陈代谢速率联系起来,他发现了相关性完全符合其预测。(必须承认,体型和新陈代谢速率不是独立的变量,小动物的新陈代谢速率比大型动物更快)The upshot is that his hypothesis—that evolution pushes animals to see the world in the slowest motion possible—looks correct. Flies may seem short-lived to people, but from a dipteran point of view they can thus live to a ripe old age. Remember that next time you try (and fail) to swat one.他的假设是进化可能让动物更慢的速度看世界,结果看起来这个假设是对的。苍蝇对人类来说似乎很短命,但是从苍蝇的角度来说,它们能活得很长。记得下次拍死一个,可能拍不到哦。 /201309/259021。
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