题目内容
Scientists who believe cell phones are dangerous have been throwing out hypotheses to explain away the negative results. Maybe something about the【1】animals raised their rates of cancer or sperm problems, so【2】the exposed animals didn't seem to be harmed. Maybe the studies should have used pulsed,【3】radiation rather than a continuous beam, the better to【4】the way we actually use mobile phones. Maybe it matters【5】the lab animals are zapped【6】in a device like a Ferris wheel or while【7】around in cages. On the other hand, if these details do【8】, maybe that in itself is significant.
Scientists who【9】claims that cell-phone radiation is causing an epidemic of brain cancer【10】that there isn't any mechanism.【11】textbook biophysics, only radiation that has enough energy to ionize molecules—that is, knock off electrons—can【12】cancer. Cell phones don't【13】energy great enough to ionize molecules in living cells. Their【14】is "far below the cancer energy threshold,"【15】physicist Robert Park of the University of Maryland, who often【16】junk science. But whenever he makes that【17】in his What's New e-newsletter, he gets【18】with angry responses insisting there are other ways low-energy radiation can【19】"I don't like cell phones and I don't like writing about cell phones," says Park,【20】the damned issue just won't go away. "
(1)
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In this sense it is true that it is the duty of society to create conditions in which such men can live. For whatever the value of any individual contribution, the general body of work is of immense value to everyone. But of course things are not so formal, in reality. There is not society on the one hand and these individuals on the other. In ordinary living, and in his work, the contributor shares in the life of his society, which often affects him both in minor ways and in ways sometimes so deep that he is not even aware of them. His ability to make his work public depends on the actual communication system: the language itself, or certain visual or musical or scientific conventions, and the institutions through which the communication will be passed. The effect of these on his actual work can be almost infinitely variable. For it is not only a communication system outside him; it is also, however original he may be, a communication system which is in fact part of himself. Many contributors make active use of this kind of internal communication system. It is to themselves, in a way, that they first show their conceptions, play their music and present their arguments. Not only as a way of getting these clear, in the process of almost endless testing that active composition involves. But also, whether consciously or not, as a way of putting the experience info a communicable form. If one mind has grasped it, then it may be open to other minds.
In this deep sense, the society is in some ways already present in the act of composition. This is always very difficult to understand, but often, when we have the advantage of looking back at a period, we can see, even if we cannot explain, bow this was so. We can see how much even highly original individuals had in common, in their actual work, and in what is called their "structure of feeling", with other individual workers of the time, and with the society of that time to which they belonged. The historian is also continually struck by the fact that men of this kind felt isolated at the very time when in reality they were beginning to get through. This can also be noticed in our own time, when some of the most deeply influential men feel isolated and even rejected. The society and the communication are there, but it is difficult to recognize them, difficult to be sure. (670)
Creative artists and thinkers achieve communication by ______.
A．According toB．Due toC．In contrast withD．With regard to
Which of the following historical events does NOT directly help to stimulate the rising of
The need for solar electricity is clear. It is safe, ecologically sound, efficient, continuously available, and it has no moving parts. The basic problem with the use of solar photo-voltaic devices is economic, but until recently very little progress has been made toward the development of low-cost photo-voltaic devices. The larger part of the research funding has been devoted to study of single-crystal silicon solar cells, despite the evidence, including that of the leading manufacturers of crystalline silicon, that the technique holds little promise. The reason for this pattern is understandable and historical. Crystalline silicon is the active element in the very successful semiconductor industry, and virtually all of the solid state devices contain silicon transistors and diodes. Crystalline silicon, however, is particularly unsuitable to terrestrial solar cells.
Crystalline silicon solar cells work well and are successfully used in the space program, where cost is not an issue. While single-crystal silicon had been proven in extraterrestrial use with efficiencies as high as 18 percent, and other more expensive and scarce materials such as gallium arsenide can have even higher efficiencies, costs must be reduced by a factor of more than 100 to make them practical for commercial use. Besides the fact that the starting crystalline silicon is expensive, 95 percent of it is wasted and does not appear in the final device. Recently, there have been some imaginative attempts to make polycrystalline and ribbon silicon, which are lower in cost than high-quality single-crystals; but to date the efficiencies of these apparently lower-cost arrays have been unacceptably small. Moreover, these materials are cheaper only because of the introduction of disordering in crystalline semiconductors, and disorder degrades the efficiencies of crystalline solar cells.
This dilemma can be avoided by preparing completely disordered or amorphous materials. Amorphous materials have disordered atomic structure as compared to crystalline materials; that is, they have only short-range order rather than the long-range periodicity of crystals. The advantages of amorphous solar ceils are impressive. Whereas crystals can be grown as wafers about four inches in diameter, amorphous materials can be grown over large areas in a single process, whereas crystalline silicon must be made 200 micron of the proper amorphous materials in necessary. Crystalline silicon solar cells cost in excess of $ 100 per square foot, but amorphous films can be created at a cost of about 50 cents per square foot.
Although many scientists were aware of the very low cost of amorphous solar cells, they felt that they could never be manufactured with the efficiencies necessary to contribute significantly to the demand for electric power. This was based on a misconception about the feature which determines efficiency. For example, it is not the conductivity of the material in the dark which is relevant, but only the photo-conductivity, that is, the conductivity in the presence of sunlight.
Already, solar cells with efficiencies well above 6 percent have been developed using amorphous materials, and further research will doubtlessly find even less costly amorphous materials with higher efficiencies. (499)
The author is primarily concerned with ______.
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