What Are Calluses And How Are They Formed

What Are Calluses And How Are They Formed?皮肤上的茧是如何形成的？人体皮肤由于劳动过程长期摩擦造成皮肤表皮细胞坏死而形成的，主要出现于手掌、足掌等部位。

长时间的受到磨檫,组织细胞的老死,角质层的严重受损形成手茧．Most of us are familiar with calluses.These extra-tough patches of skin are generally quite useful–we might even say handy–because they act like a kind of natural armor, protecting areas of skin that get an unusual amount of wear and tear. Have you ever wondered exactly what a callus is, or how it forms on your skin?Callus formation is triggered by pressure or abrasion. The heel of your foot as it rubs inside your shoe, or the palm of your hand if you’re doing a lot of manual labor are good examples of this.While it might feel like a callus is something extra, added to your skin, it’s actually just a build-up of what’s already there.Here’s How It WorksYour skin has a number of layers of different types of cells.The outermost is a layer of hardened, dead cells. This top layer is usually about twenty-five cells thick, and it constantly replaces itself as the outermost cells flake off to be replaced by new hardened, dead cells underneath.All About FrictionIf your skin is subject to an unusual amount of friction, this layer of dead cells increases. New dead cells are added faster than the old ones slough away. This can build up the outer layer from twenty-five cells thick to over a hundred cells thick. You’ve grown a callus.While calluses are generally useful, if the process continues unchecked a callus can thicken into a cone-shaped structure called a corn. These super calluses can be quite painful, and may require the attention of a doctor.译文对于“老茧”，我们都很熟悉。

这些皮肤上突出的硬皮是很有用的，也可以说是方便，因为他们扮演着保护常磨损皮肤的天然盔甲的角色。

你是否思考过什么是老茧？他又是怎样形成的？老茧是由压力和摩擦而形成。

脚后跟的茧是由其在鞋里摩擦而形成，正如手茧是在大量的劳动过程中形成。

尽管看起来似乎是皮肤上多出的部分，然而事实是已经存在的皮肤角质的累积。

形成过程皮肤是由若干层不同类型的皮肤构成。

表层是一些坏死的硬细胞，通常有25个细胞那么厚，表层细胞不断的脱落，取而代之的是下层硬的坏死细胞，由此而完成自我更替过程。

一切皆由摩擦引起假如皮肤受到不寻常量的摩擦，这层坏死细胞将会增加，新的坏死细胞增长速度比旧细胞脱落的速度快，这就致使皮肤表层的厚度增加到100个细胞那么厚，由此，老茧便形成。

虽然一般来讲，茧是有益的，但如不控制其过程，老茧厚度就会增加到被称作鸡眼的锥形结构，那样就会很疼，甚至需要去看医生。

Ocean Heat海洋热量Ya?l: I hear a lot about global warming, but how do scientists take the Earth’s temperature?Don: Great question. Most of the excess heat trapped by greenhouse gasses like carbon dioxide ends up in the oceans.That’s because the earth’s oceans are kind of like a giant sponge that can hold a lot of heat for a long time.Y: The oceans are also huge–in fact, they cover most of the planet, and some parts of the oceans are warmer and some are colder. So it’s not like you can just stick a thermometer in somewhere and say, “OK, that’s the ocean’s temperature.”D: Of course not. Scientists take thousands of temperature readings from different parts of the oceans. They use a combination of heat sensitive satellites and thousands of floats that directly measure the temperature of ocean water at various depths. Together, these instruments allow scientists to calculate an average ocean temperature.Y: It’s an ongoing process, and scientists are always trying to get more accurate measurements. But they’ve found that the oceans have in fact been warming at a rate that corresponds with how much heat scientists think has been trapped by greenhouse gasses.D: This may not sound too bad; as long as the oceans are absorbing most of the extra heat, why worry? But higher ocean temperatures cause icebergs and ice shelves to melt, which raises sea level. And warmer oceans could affect weather patterns in ways that scientists don’t fully understand.Y:So, warming of the oceans affects us all.Ya?l: 我听到很多关于与全球变暖的事情，但科学家们是怎么测量地球温度呢？Don: 问得好。

温室里的大多余热象二氧化碳之类气体的都被海洋吸收了。

这是因为地球就象一块巨大的海绵，可以长时间容纳大量的热量。

Y: 实际上海洋是很大的，它占据了地球大部分的面积。

海洋有的地方比较暖和，而有的地方比较寒冷。

所以并不是那样，你拿个温度计随便测量某个地方的温度，然后说，“好了，这就是海洋的温度”。

D: 当然不是那样。

科学家们会在海洋的不同区域测量无数次温度。

他们把热敏感卫星和许多直接测量不同深度的海水温度的漂浮物结合起来。

这些工具让科学家们计算出一个平均海温。

Y: 这是一个持续的过程，科学家们一直试图做更精确的测量。

但他们发现，海洋变暖的速度其实与科学家们认为被温室所困住的气体的多少成比例的。

D: 这听起来也许不是太糟糕，只要是海洋吸收掉大部分多余的热量，为什么要担心呢？但较高的海洋温度会造成冰山和冰架融化，这引起了海平面上升。

变暖的海洋可能会以一种科学家不理解的方式影响天气。

Y: 因此，海洋变暖影响着我们每一个人。

The Habitable Zone宇宙生命奥秘适居带(HZ)是天文学上给一种空间的名称，指的是那里的情况有利于生物的存在，或许可以发现像地球这样的生命体。

有两种区域是有可能的，一个是在行星系内，另一个则存在于星系之中。

在适合的区域内的行星和天然卫星是最佳的候选者，这些地球外的生命有能力生活在类似我们的环境下。

天文学家相信生命最可能发生在像太阳系这样的星周盘适居带(CHZ)和大星系的星系适居带 (GHZ)内。

适居带也许是指"生命带"、"绿带"或"Goldilocks带"(因为既不太热也不太冷，就是刚好)。

在我们的太阳系，适居带被认为从0.95天文单位延伸至1.37天文单位。

Y: Do you think there's life on other planets Don?D: It seems perfectly reasonable that there would be Yaël. what with how unfathomably large the universe is.Don't you think？Y:I do.But then again, life is a tricky thing. So much has to fall into place for the conditions for life as we know it to be possible.For instance, a planet has to be just the right distance from the star it revolves around.D:How is that?Y:If it’s too close to its star, the heat from th e star would cause any water on the planet to boil away. If it’s too far away, the opposite problem occurs: the cold temperature would cause water to freeze. The range of distance from a star that will allow water to remain a liquid is called the habitable zone.D:So we Earthlings are lucky I guess that we are just the right distance away from the sun.Y:Very lucky it seems.In 2007, scientists discovered the first two Earth-like planets outside our solar system that appear to be located near or within their star’s habitable zone. Previously discovered planets have had masses more akin to Jupiter’s. The planets orbit the same star and are known as Gliese 581c and Gliese 581d.D:Wow,so there is other life out there?Y:Not so fast, upon further investigation, it seems that Gliese 581d may be the only one of the two actually in the habitable zone, and its orbit seems to take it in and out of the zone. Not to mention as I said, a lot of factors must come into play for life to exist. Being within the habitable zone is just one of them.译文Y:Don，你认为其他行星上会有生命存在吗？D:似乎完全有理由相信有生命存在。