共查询到20条相似文献，搜索用时 23 毫秒
1.
Smith KR 《Science (New York, N.Y.)》1978,201(4356):609-611
Present accounts of U.S. energy consumption are incomplete in two ways: they include neither the direct military uses of nuclear energy nor the mostly military, nonfuel uses of uranium. Preliminary estimates indicate that significant distortions are created in the data on U.S. nuclear energy consumption patterns as a result of these omissions. 相似文献
2.
Smith RJ 《Science (New York, N.Y.)》1982,216(4541):30-34
Early this year, the U.S. land-based force of nuclear missiles became vulnerable to a preemptive attack by the Soviet Union, as the Soviets deployed a large number of highly accurate warheads on their own missiles. They first demonstrated this capability in 1977. Since then, U.S. missile vulnerability has come to assume great importance in superpower relations. Western observers have portrayed the Soviet achievement as a sign of aggression, and made missile vulnerability into a symbol of declining American military strength. The government has proposed a vast military buildup of nuclear weapons, supposedly made necessary by this new threat. But the public is increasingly skeptical, and support for some form of arms control is growing. The first article in this series examines how the United States learned of the Soviet accuracy, and why it caused such great alarm. The next article will examine the Reagan Administration's response to this threat. 相似文献
3.
Perceived risk, trust, and the politics of nuclear waste 总被引：1，自引：0，他引：1
The Department of Energy's program for disposing of high-level radioactive wastes has been impeded by overwhelming political opposition fueled by public perceptions of risk. Analysis of these perceptions shows them to be deeply rooted in images of fear and dread that have been present since the discovery of radioactivity. The development and use of nuclear weapons linked these images to reality and the mishandling of radioactive wastes from the nation's military weapons facilities has contributed toward creating a profound state of distrust that cannot be erased quickly or easily. Postponing the permanent repository and employing dry-cask storage of wastes on site would provide the time necessary for difficult social and political issues to be resolved. 相似文献
4.
Marshall E 《Science (New York, N.Y.)》2000,289(5478):382-383
Anthrax bacterium, once the deadly scourge of goat-hair workers, has become the bane of the U.S. defense establishment. Without infecting a single soldier, it has created a logistical headache for the Pentagon, as military contractors have fallen far short of supplying a vaccine that will protect all troops and be acceptable to health authorities. Last week military officials were forced to beat a hasty retreat in their current efforts, raising the hackles of legislators who already had serious doubts about the program. 相似文献
5.
The accompanying article of Horo witz et al. concluded with the view that the COSPAR recommendations re garding Mars should be adjusted to re flect new environmental information. Specifically, it was concluded that viable terrestrial microorganisms which are transported to Mars inside solid components in sealed spaces have a low probability of being released to the sur face or atmosphere, and that, if any are released, they are not likely to in fect the planet. We suggest, in addition, that both the COSPAR recommenda tions and U.S. planetary quarantine policy should be altered to take into account past and continuing Soviet prac tice regarding the. exploration of Mars and Venus. No amount of analysis by COSPAR, or of costly, self-imposed restrictions by the U.S. on its own planetary exploration program, can reduce the probability of contamination of either Venus or Mars below what the Soviets have already made it, or will make it as they continue their large planetary effort. All that U.S. policy can accomplish is to insure that U.S. efforts do not significantly increase the probability above that level. Any rec ommended policy which would require the U.S. to apply significantly more stringent restrictions is illogical in that, in effect, the U.S. would be asked to increase greatly the cost and complexity of its planetary program without achieving any significant reduction in the probability of actual contamination. There exists some parallelism be tween the problem of planetary quaran tine and that of radioactive fallout from atmospheric nuclear testing, al though the desirable solution to the quarantine problem is not merely to stop all activity. Both are multilateral problems, and individual national policy necessarily must reflect the policy of other nations. Thus, the real questions that must be faced by COSPAR, and by the U.S., are, (i) What is the prob able number of viable terrestrial micro organisms alreadyr transported to Venus and to Mars? and (ii) What is the to tal number to be expected in the next decade or so from foreseeable Soviet efforts alone? Then COSPAR can rec ommend, and the U.S. can decide, that the total U.S. contribution should be equal to some specified fraction of the total present and future Soviet contribu tion. This approach in turn suggests that every effort should be made to induce the Soviets to supply additional de tails on the Zond 2 and Venus 3 mis sion and trajectory and, particularly, on the procedure used for sterilizing the components and assembly of both space craft. With such information, the proba ble number of viable terrestrial microor ganisms deposited on Venus and Mars could be estimated well enough to per mit a. realistic quantitative analysis of what U.S. policy and practice should be. However, if more complete informa tion on Soviet practice cannot be ob tained, then, it seems to us, the U.S. has no logical alternative but to per mit greater engineering freedom in lander delivery technique and to ac cept gaseous and other nonthermal sterilization procedures, where neces sary, in its own program. By relying on the demonstrated U.S. spacecraft reliability to insure that the U.S. con tribution to planetary contamination will remain significantly less than the Soviet contribution, we could reduce significantly the cost and time required to carry out serious scientific investiga tions of the surfaces of Venus and Mars. 相似文献
6.
Makarov EM Makarova OV Urlaub H Gentzel M Will CL Wilm M Lührmann R 《Science (New York, N.Y.)》2002,298(5601):2205-2208
Major structural changes occur in the spliceosome during its activation just before catalyzing the splicing of pre-messenger RNAs (pre-mRNAs). Whereas changes in small nuclear RNA (snRNA) conformation are well documented, little is known about remodeling of small nuclear ribonucleoprotein (snRNP) structures during spliceosome activation. Here, human 45S activated spliceosomes and a previously unknown 35S U5 snRNP were isolated by immunoaffinity selection and were characterized by mass spectrometry. Comparison of their protein components with those of other snRNP and spliceosomal complexes revealed a major change in protein composition during spliceosome activation. Our data also suggest that the U5 snRNP is dramatically remodeled at this stage, with the Prp19 complex and other factors tightly associating, possibly in exchange for other U5 proteins, and suggest that after catalysis the remodeled U5 is eventually released from the postsplicing complex as a 35S snRNP particle. 相似文献
7.
The safety goals of the U.S. Nuclear Regulatory Commission 总被引：1，自引：0，他引：1
D Okrent 《Science (New York, N.Y.)》1987,236(4799):296-300
In August 1986, after 6 years of effort, the U.S. Nuclear Regulatory Commission adopted a Policy Statement on safety goals for nuclear power reactors. The commission's qualitative goals state that individual members of the public should be provided a level of protection from the consequences of nuclear power plant operation such that they bear no significant additional risk to life and health, and societal risks to life and health from nuclear power should be comparable to or less than the risks of generating electricity by viable competing technologies and should not be a significant addition to other societal risks. The commission's safety goal Policy Statement also includes quantitative design objectives. 相似文献
8.
美国军事司法禁止强制性自证其罪规则,与"米兰达规则"有着本质区别。尽管二者在法源上相同,但建立的规则不同。美国军事司法禁止强制性自证其罪规则确立了禁止刑讯逼供原则、预先告知原则和非法证据排除规则,但虐囚事件充分暴露了美国军事司法禁止强制性自证其罪规则的本质。 相似文献
9.
Multiple copies of a gene that encodes human U1 small nuclear RNA were introduced into mouse C127 cells with bovine papilloma virus as the vector. For some recombinant constructions, the human U1 gene copies were maintained extrachromosomally on the viral episome in an unrearranged fashion. The relative abundance of human and mouse U1 small nuclear RNA varied from one cell line to another, but in some lines human U1 RNA accounted for as much as one-third of the total U1. Regardless of the level of human U1 expression, the total amount of U1 RNA (both mouse and human) in each cell line was nearly the same relative to endogenous mouse 5S or U2 RNA. This result was obtained whether measurements were made of total cellular U1 or of only the U1 in small nuclear ribonucleoprotein particles that could be precipitated with antibody directed against the Sm antigen. The data suggest that the multigene families encoding mammalian U1 RNA are subject to some form of dosage compensation. 相似文献
10.
海南省热带农业废弃物资源化利用状况及对策 总被引：1，自引：1，他引：0
海南终年可以进行农业生产,以至终年均有大量农业废弃物产生。文章阐述海南省热带农业废弃物资源化利用状况及存在的问题,提出海南省热带农业废弃物资源化利用的对策,其目的在于促进海南省热带农业废弃物资源化利用水平的提高。 相似文献
11.
T R LaPorte 《Science (New York, N.Y.)》1978,201(4350):22-28
The article argues that insufficient attention has been paid to the operational aspects of the U.S. radioactive waste management system when it grows to the scale necessary to handle wastes produced by a fully deployed plutonium economy. Without such information, many of the unsettling speculations which have become part of the public debate and are summarized herein cannot be clearly addressed. The article then outlines the types of information necessary to begin estimating the costs and consequences of radioactive waste management. Finally, an index of social exposure to radioactive hazard is proposed to improve the basis for policy decisions in this area. 相似文献
12.
Our foregoing analysis of the role of a comprehensive test ban leads us to the following conclusions. 1) A CTB by itself will have little direct effect on the arms race between the superpowers. It would not hinder their nuclear arms production and deployment nor would it necessarily present a significant obstacle to the development of new nuclear weapons systems, despite limiting the development of new nuclear warhead designs. It can hardly make a dent in the destructive capability of the superpowers or in their ability to step up the pace of the arms race. 2) The chief merits of a CTB reside in the political sphere. It would help promote detente and could help to escalate interest in arms control agreements of broader scope. But in neither of these effects would it be as significant as a successful SALT (strategic arms limitation talks) agreement. The CTB also lingers as a piece of unfinished business since the signing of the LTB in 1963. The question can be and has been raised, "If the superpowers are serious about arms control, why have they not accepted the CTB, which is simple in concept and in form and is also free of serious military risks?" Such doubts about the sincerity of the superpowers' willingness to limit their own arms development will persist as long as there is no CTB. Substantial agreement at SALT would lessen some of this effect too, but would not eliminate it completely. 3) Recent progress in seismic identification has been impressive, and other means of obtaining technical intelligence about nuclear testing have probably also improved greatly. In addition, research on the technical means of on-site inspection has demonstrated its limited effectiveness. Therefore, the role of on-site inspections as an added deterrent to cheating on a CTB has diminished substantially. This is not to say that detection and identification of all nuclear tests is possible now, or ever, but only that on-site inspection would add very little to the other technical means now available for verification. 4) It will become increasingly difficult in the United States to oppose the CTB on the basis of risks that accompany possible Soviet evasion of a treaty that does not include the right of onsite inspection. The opposition to a CTB is now likely to shift to the more direct argument that nuclear testing is important to keep pace with continuing worldwide technical and military developments. The justification for U.S. testing is only in part because of advances in Soviet nuclear technology per se. Those opposing a CTB may argue that it makes little sense, and may even be courting danger, to freeze nuclear technology alone and that banning nuclear tests should await an agreement that copes with all military research and development and all qualitative improvements in weapons systems. This directly confronts the argument that the unique virtue of a CTB is that it provides a simple and feasible first step in the very complicated problems of controlling military technology. 5) The mutual deterrence of the superpowers will not be compromised if a CTB agreement is reached and one side or the other clandestinely violates such an agreement. The state of nuclear technology in both countries is mature, and the destructive capability of their nuclear arsenals can be easily maintained. Whatever small improvements can come as a consequence of clandestine testing would hardly affect the strategic balance. 6) It seems unlikely that China and France will agree to stop testing in the near future. These countries refused to join the nonproliferation treaty, which did not affect their nuclear programs, and it is doubtful that, proceeding from military considerations alone, they would join a CTB. Their nuclear programs are still not mature, and a CTB would freeze their positions of inferiority with respect to the superpowers. There may, however, be wider political and security arrangements to induce them to participate. Cessation of tests by the other nuclear powers might serve as an inducement to China and France to refrain from testing. 7) The key near-nuclear powers, such as Japan, India, and Israel, are much more concerned with the military activities of their neighbors than they are with those of the superpowers. The modest nuclear restraints that a CTB imposes on the superpowers are hardly likely to have a direct impact on the approach of these countries to their own security. However, for these critical near-nuclear countries a CTB may be much more acceptable than the nonproliferation treaty. A CTB would not prohibit the production of fissionable material, the development of nuclear weapons technology short of testing, nor the stockpiling of untested nuclear weapons, and is therefore less restrictive. Consequently, these powers may be willing to ratify a CTB, but not the nonproliferation treaty. On the other hand, the CTB may provide them with a ready excuse for not succumbing to the pressure to ratify the nonproliferation treaty, if indeed they need excuses or would bow to such pressure. 8) A CTB is of very little added, direct significance to other nonnuclear powers who have already ratified or are about to ratify the nonproliferation treaty. It may only lessen their pique about the treaty's being highly discriminatory-the treaty imposes no restraints on the nuclear weapons programs of the nuclear powers, while the CTB restricts all parties to the agreement. 9) Peaceful nuclear explosions do not now show great promise and significance for economic development. What can be done with peaceful explosions can often be done by other means, although possibly at a slightly higher cost. On the other hand, making allowance for peaceful explosions greatly complicates a CTB. A useful approach to the problem of banning military tests but not foregoing indefinitely the use of peaceful explosions might, therefore, be to ban all nuclear explosions for a period of several years and to stipulate in the agreement that in that time there would be negotiations on how peaceful explosions may be controlled in a way that would not jeopardize the CTB. 相似文献
13.
Nuclear weapons that are safe and secure, reliable, survivable, and effective will be a critical element of this nation's deterrent for the foreseeable future. The existence of these weapons reflects the tension that exists between the United States and the Soviet Union. Nuclear test bans will not reduce or eliminate nuclear weapons or this tension. Imprudent nuclear test bans, however, could impair the viability of this vital element of U.S. security. New, more restrictive test limitations would not enhance our national security. They do not address the two most important issues-namely, major reductions in strategic and conventional forces of both the Soviet Union and the United States, and a widespread lessening of tension between our two countries. In fact, it is conceivable that the diversion of political attention from arms reduction efforts and the distrust generated by test-ban verification problems could actually increase tensions between the two countries. We believe that more restrictive test limitations or a nuclear test ban should be considered only as part of an integrated and comprehensive approach to arms control. We must reduce the numbers of the most destabilizing weapons and the overall size of the strategic arsenals through negotiations. A restrictive test ban may be a proper last step in our quest for nuclear arms control and a stable peace, but it would, in our opinion, be an imprudent first step. Further test limitations will be consistent with increased stability and decreased tension between the United States and the Soviet Union only if they are instituted after major stabilizing reductions are made in the strategic nuclear and conventional forces of both countries. 相似文献
14.
本文将美国和苏联自50年代以来的农业生产进行了初步的比较研究。总的讲来,苏联的农业落后于美国.除自然条件和某些技术外,最主要的原因是苏联的农业政策和组织管理都过于刻板,过份强调集中计划而忽略生产者的自决权.文章最后提及近年来苏联对农业进行改革已初见成效.只要坚持改革,苏联的农业前景将有所改观。 相似文献
15.
刘军荣 《湖南农业大学学报(自然科学版)》2013,(5):120-124
二战后美国经济周期波动发生显著变化。相比二战之前，美国经济周期扩张期拉长，衰退期缩短，二者之间形成剪刀差。经济周期长度、扩张期跨度和紧缩期跨度的离散度远远大于战前。二战后至今，美国经济中周期出现（朱格拉周期）呈拉长的趋势，扩张期远远长于衰退期，中周期（朱格拉周期）和短周期（基钦周期）的波幅经历了从小到大的阶段性变化。 相似文献
16.
张滢 《农业图书情报学刊》2019,31(7):56-65
由日本汽车制造商丰田公司于20世纪中叶创建的Just in Time（JIT）（即时供应）几十年来一直是生产和库存管理的领先理念。美国的图书馆越来越多地将这种理念应用于管理馆藏和服务工作。这与几个世纪以来使用的更传统的Just-in-case （JIC）（备需供应）模型不同。从馆藏选择、馆藏建设、馆藏开发到现在的馆藏服务,分析描述图书馆馆藏专业活动的术语的演变,反映了图书馆在不同的时间建设馆藏的方法。 JIT馆藏建设服务已经在美国的大多数图书馆中得到应用。什么是JIT馆藏服务以及它是如何应用的？本文通过美国图书馆的实践描述了JIT模型。 相似文献
17.
Concentrations of I(131) in the thyroids of deer from Washington, Colorado, and Maryland, and of caribou from Alaska were measured after the resumption of nuclear weapon tests by the U.S.S.R. on 1 September 161. Maximum concentrations occurred nearly 2 months after the first nuclear test and then decreased at an effective half-time of about 15 days. Thyroids from Washington and Colorado deer showed the highest concentrations, thyroids from Alaskan caribou the lowest. 相似文献
18.
U.S. trade policy since the end of World War II has rested on two pillars: a multilateral approach to trade agreements and a commitment to rules rather than results. Support for each principle is rapidly eroding because of, among other things, record trade deficits and pessimism about the effects of exchange rate movements on trade flows. In fact, however, U.S. trade deficits are largely "homemade," and trade flows are responsive to changes in exchange rates. The U.S. has played a leadership role in promoting freer trade on a multilateral basis. Adoption of any one of a number of recently proposed alternative trade policy frameworks would be counter to that role. 相似文献
19.
Malakoff D 《Science (New York, N.Y.)》2000,288(5475):2300-2301
A congressional report released this week details dozens of sometimes clumsy attempts by foreign agents to obtain nuclear secrets from U.S. nuclear scientists traveling abroad, ranging from offering scientists prostitutes to prying off the backs of their laptop computers. The report highlights the need to better prepare traveling researchers to safeguard secrets and resist such temptations, say the two lawmakers who requested the report and officials at the Department of Energy, which employs the scientists. 相似文献
