【一起来听写】nova日志

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10.4
Listen to part of a lecture in a biology class.
Okay! Now I want to talk about an animal that has a fascinating set of defense mechanisms and that’s the octopus, one of the unusual creatures that live in the sea. The octopus is prey to many species, including humans, so how does it escape the predators? Well, let me back up here a second. Anyone ever heard of Proteus?
Proteus was god in Greek mythology who would change form. He could make himself look like a lion or a stone or a tree, anything you wanted and he could go through a whole series of changes very quickly. Well, the octopus is the real world version of Proteus. Just like Proteus, the octopus can go through all kinds of incredible transformations. And it does this in three ways: by changing color, by changing its texture, and by changing its size and shape.
For me, the most fascinating transformation is when it changes its color. It’s a normal skin color, the one it generally presents, is either red or brown or even grey and its speckled with dark spots. But when it wants to blend in with its environment to hide from its enemies, it can take on the color of its mediate surroundings, the ocean floor, a rock, a piece of coral, whatever? Charles?
Do we know how that works, I mean how they change colors?
Well, we know that the reaction that takes place is not chemical in nature. The color changes are executed by two different kinds of cells in the octopus’ skin, mainly by color cells on the skin surface called chromatophores.
chromatophores consist of tiny sacks filled with color dye. There might be a couple hundred of these color sacks per square millimeter of the octopus’ skin, and depending on the species, they can come in as many as five different colors. Each one of these sacks is controlled by muscles. If the muscles are relaxed, the sack shrinks and all you see is a little white point. But if the muscles contract, then the sack expands, and you can see the colors. And by expanding different combinations of these colors sacks to different degrees, the Octopus can create all sorts of colors. Yes? Elizabeth?
And just with various combinations of those five colors, they can recreate any color in their environment?
Well, they can no doubt create a lot with just five colors, but you are right, may be they can’t mimic every color around them, so that is where the second kind of cell comes in. Just below the chromatophores is a layer of cells that reflect light from the environment, and these cells help the octopus create a precise match with the colors that surround them. The colors from the color sacks are supplemented with colors that are reflected from the environment, and that’s how they are able to mimic colors with such precision. So that’s how octopuses mimic colors. But they don’t just mimic the colors in their environment; they can also mimic the texture of objects in their environment. They have these little projections on their skin that allow them to resemble various textures. The projections are called papillae. If the octopus wants to have a rough texture, it rises the papillae, if they want to have a smooth texture flattens out the papillae,
so it can acquire a smooth texture to blend in with the sandy bottom of the sea. So the octopus has the ability to mimic both the color and the texture of its environment. As it truly amazing how well it can blend in with its surroundings, you can easily swim within a few feet of an octopus and never see it.
I read that they often hide from the predators by squirting out a cloud of ink, or something like that.
Yes, the octopus can release a cloud of ink if it feels threatened. But it doesn’t hide behind it, as it generally believed, the ink cloud is... it serves to distract a predator while the octopus makes its escape. Now there is a third way the octopuses can transform themselves to blend in with or mimic their environment, and that’s by changing their size and shape, at least their apparent size. The muscular system of the octopus enables it to be very flexible to assume all sorts of shapes of postures. So it can contract into the shape of a little round stone and sit perfectly still on sea floor. Or it can nestle up in the middle of a plant and take the shape of one of the leaves. Even Proteus would be impressed I think.

Octopus 章鱼
Proteus 多变的人，普罗西斯-希腊海神
Chromatophores 色素细胞
squirting 喷出，注射
Papillae 乳头状突起


10.5
Scientist investigating a popular herbal treatment for enlarged prostate, saw palmetto, have concluded it is no more effective than a placebo.
But the conclusion comes from a study included hundreds of men in their forties and order.
As men age, the prostate often gets larger. The prostate surrounds the urethra, which carries urine from the bladder to the penis. And enlarged prostate can impede the flow of urine, causing a variety of symptoms. There are prescription drugs which can ease symptoms but many men prefer the “natural” alternative: an extract from the saw palmetto tree, native to the American Southeast.
It’s actually a very complex extract. It has quite a number of different chemicals and molecules within it, several of which are plausible agents to affect the way a man urinates, to even shrink the prostate. Doctor G of Washington university medical school in Saint Louis, is one of the co-author of a paper describing a new study on the effectiveness of saw palmetto.
The men in the study were randomly assigned to two groups, one got progressively larger doses of saw palmetto and the other group got a placebo – dummy pill. It was a double-blind study neither the participants nor staff knew who was getting which.
They filled out a standard questionnaire used by the urologists to assess prostate enlargement. It includes questions like, how many times did you need to get up to urinate at night, how often did you experience frequency, urgency, and the sense of incomplete bladder emptying. This is a standard symptom score that has been used for close to 20 years.
By the end of the study, actually about 16 months, A says the symptoms scores improved for both group of men. But there was no difference in magnitude of symptom score improvement between placebo and saw palmetto.
And increasing the dose of saw palmetto didn’t make any difference. Some critics found fault with a previous study that found no benefit to saw palmetto, saying the dosages were too low.
Saw palmetto is safe and thanks to the so-called placebo effect, it does improve symptoms, but A says it doesn’t address more serious prostate conditions. Such as urinary tract infections, complete inability to urinate or even the need to have surgery. The drugs we have significantly reduce a man’s chance of ever experiencing those, in addition to improving his symptoms.
He says that since saw palmetto does not require a prescription, he notes that patients who use the herbal supplements might not see a doctor. That raises the risk that much more serious problems, like the early stages of prostate cancer, might go undiagnosed.
Prostate 前列腺
saw palmetto 蔡氏菠萝榈
urethra 尿道
Urine 尿
bladder 膀胱
penis 阴茎
symptoms 症状 ease减轻
Dummy 虚拟的
urologists 泌尿科医生