Cost of space-based laser ballistic missile defense

Orbiting platforms carrying infrared lasers have been proposed as weapons forming the first tier of a ballistic missile defense system under the President's Strategic Defense Initiative. As each laser platform can destroy a limited number of missiles, one of several methods of countering such a system is to increase the number of offensive missiles. Hence it is important to know whether the cost-exchange ratio, defined as the ratio of the cost to the defense of destroying a missile to the cost to the offense of deploying an additional missile, is greater or less than 1. Although the technology to be used in a ballistic missile defense system is still extremely uncertain, it is useful to examine methods for calculating the cost-exchange ratio. As an example, the cost of an orbiting infrared laser ballistic missile defense system employed against intercontinental ballistic missiles launched simultaneously from a small area is compared to the cost of additional offensive missiles. If one adopts lower limits to the costs for the defense and upper limits to the costs for the offense, the cost-exchange ratio comes out substantially greater than 1. If these estimates are confirmed, such a ballistic missile defense system would be unable to maintain its effectiveness at less cost than it would take to proliferate the ballistic missiles necessary to overcome it and would therefore not satisfy the President's requirements for an effective strategic defense. Although the method is illustrated by applying it to a space-based infrared laser system, it should be straightforward to apply it to other proposed systems.     

寡糖作为生物农药在微生物病害防治中的作用机理

植物在与病原菌的长期相互作用中,逐渐发育出自我防御响应体系,当受到微生物病原菌侵染时,会启动防御相关基因表达,产生的防御反应使植物免受微生物病害感染。这种防御响应是通过植物细胞表面上的受体蛋白与病原菌激发子相互结合,使寄主植物识别侵染微生物,并通过信号传导网络在细胞内传递感染信息,启动抗性基因表达,产生防御反应。研究证明,寡糖能够作为外源性激发子诱导植物产生防御响应,因此,寡糖作为生物农药在微生物病害防治中具有十分重要的作用。     

Uncertainties in building a strategic defense

Building a strategic defense against nuclear ballistic missiles involves complex and uncertain functional, spatial, and temporal relations. Such a defensive system would evolve and grow over decades. It is too complex, dynamic, and interactive to be fully understood initially by design, analysis, and experiments. Uncertainties exist in the formulation of requirements and in the research and design of a defense architecture that can be implemented incrementally and be fully tested to operate reliably. The analysis and measurement of system survivability, performance, and cost-effectiveness are critical to this process. Similar complexities exist for an adversary's system that would suppress or use countermeasures against a missile defense. Problems and opportunities posed by these relations are described, with emphasis on the unique characteristics and vulnerabilities of space-based systems.     

An industry picture of u.s. Science policy

With regard to promoting the competitiveness of U.S. industry, federal science policy is performing unevenly. Federally supported basic research is not well aligned with industrial needs, although the National Science Foundation's Engineering Research Centers and similar programs are improving matters. Large-scale federal undertakings in science and technology, such as the Apollo program and now the Strategic Defense Initiative, actually tend to divert resources away from commercial research and development. Needed are federal and industrial leaders who will work together to serve the interests of both competitive industry and efficient government in the United States.     

哈茨木霉菌T6对茄子幼苗根部防御酶系的研究

以茄子的不同抗、感黄萎病品种为材料,研究苗期感染黄萎病菌后,根部组织内防御酶系的活性变化。结果表明:经哈茨木霉T6处理的不同抗、感茄子品种幼苗根系的PAL、POD、PPO和SOD存在明显变化,4种酶活性与对照相比均有一定程度的升高,但抗病品种的酶活性增加幅度高于感病品种。证明茄子根系经诱导后可产生植保素等相关物质参与抵抗黄萎病。     

Natural philosophy in the constitution

The natural philosophers who wrote the U.S. social contract held the advancement of science to be the supreme exercise of citizen sovereignty. The rising nation, in the late 19th century, established the seat of that sovereignty in its universities. Today those institutions have come to be regarded as contract research centers at the service of the federal government. Research contracts in support of the proposed Strategic Defense Initiative are pressed on them against the consensus of the scientific community that holds this "Star Wars" enterprise to be technically infeasible. The time has come to reconstruct the relation between the federal government and university science in the spirit of our social contract.     

Public health. Surveillance and privacy

Surveillance is the radar of public health. It has provided the foundation for public health planning, intervention, and prevention. Important ethical issues regarding privacy--the extent to which name-based reporting violates the trust and assumptions made about how personal medical information will be treated--are raised by public health surveillance. This policy forum looks at the contexts of differing responses from the public health communities and general public to surveillance efforts.     

沈阳地区人工增雨天气系统及作业时机

采用数理统计、归类分析沈阳地区人工增雨案例。结果表明,增雨天气系统主要有东北冷涡、高空槽、华北低压、高压后部和冷锋云系。增雨的适宜高度在云层的中上部约3 000～6 000 m,增雨时机要在雷达监测下,系统移动缓慢或稳定维持且处于发展或成熟阶段。稳定深厚云层宜飞机增雨,不稳定移动快宜火箭高炮增雨。     

基于天基信息的农业物流综合服务平台架构设计

阐述了天基信息服务平台构建涉及的地理信息、遥感和导航技术(3S技术)、云计算和天基信息服务技术。针对现代农业物流需求和发展趋势,借助天基信息提供的货源、位置、时间等信息的优势,提出了一种基于天基信息的农业物流综合服务平台设计方案,包括系统的架构设计和各组成系统的功能,最后讨论了该方案的特点和优势。     

Air pollution surveillance systems

Atmospheric surveillance is necessary in order to identify airborne pollutants, to establish ambient concentrations of these pollutants, and to record their trends and patterns. Air pollutants may occur in the form of gases, liquids, and solids, both singly and in combination. Gaseous pollutants make up about 90 percent of the total mass emitted to the atmosphere with particulates and aerosols accounting for the remaining 10 percent. Small particulates are of particular importance because they may be in the respirable size range. These small particles may contain biologically active elements and compounds. Furthermore, they tend to remain in the atmosphere where they interfere with both solar and terrestrial infrared radiation, which may affect climate on a global basis.     

基于GIS的建设用地批后视频监管系统研究

[目的]建设用地批后监管工作一直是国土资源管理的薄弱环节,解决缺乏动态监管的有效途径和技术,引起的信息获取速度慢、共享程度低等问题.[方法]对目前GIS技术和视频监控技术进行了研究,将GIS技术和视频监控技术相结合,应用于建设用地批后监管信息系统中.[结果]研究了基于GIS的建设用地批后视频监控系统的功能特点、整体架构的设计以及实现该系统的思路.[结论]创新了国土资源执法的监管方式,改进了传统监管方式的不足,实现了由被动执法向主动防范的转变.     

冷锋云系的多普勒雷达反射率因子特征总结

[目的]总结冷锋云系的多普勒雷达反射率因子特征。[方法]从反射率因子特征上来研究冷锋云系,利用2002～2007年哈尔滨新一代天气雷达资料,总结了冷锋云系的反射率因子特征。[结果]冷锋所产生的云总体上说呈带状,但其间云体有间隙,且强度分布不均匀;多数移动快的冷锋为长而窄的回波带,移动缓慢的冷锋或弱冷锋,则呈宽广的片状或片絮状回波;面积大的冷锋云系通过测站基本都可以分析出径向速度由西北风转为西南风;随着月份的不同,反射率因子特征也有很大的变化。在冬季,冷锋云表现为层状云,反射率因子特征非常弱,一般面积较大,呈片状,但结构松散,回波间有间隙,其中夹杂着几块比较强的回波;在冷锋两侧易产生强度大的对流单体回波,一般会随着整体云带移动,移速、移向基本一致;干冷锋移过时,易局地产生强对流,以对流云为主,回波面积较小,一般从径向速度图中分析不出风向转变,但单体的强度特征明显,一般有＂三体散射＂、＂旁瓣＂、＂弱回波区＂特征,具有超级单体的特征。[结论]该研究为多普勒雷达在黑龙江省监测灾害天气的应用上起到了积极作用。     

博兴县冰雹灾害分析与防御对策

利用博兴县冰雹灾害历史资料,通过分类统计的方法,确定了冰雹灾害的多发区,找出了高空低涡横槽是造成冰雹灾害的主要影响天气系统,分析了博兴县冰雹灾害的年、月、日分布和发生规律及冰雹天气的主要侵袭路径,从工程类和非工程类6个方面提出了博兴县防御冰雹灾害的措施;通过开展防雹作业前后雹灾面积对比,对博兴县人工防雹作业效果进行评估;利用雷达观测资料,结合当地经验,提出了高炮人工防雹作业效益的计算方法。     

技术性贸易壁垒对中国农产品出口的影响——基于“一带一路”国家的实证分析

采用2004—2018年的数据对“一带一路”沿线国家的农产品技术性贸易壁垒(简称TBT)现状及其对我国农产品出口的影响进行实证分析发现:(1)西亚地区的TBT通报最为活跃,对乳制品、肉制品等食品标准要求严格;东南亚国家其次,关注酒精饮料的标签设计,以及新鲜水果、家禽等产品的检验检疫、运输方式等;南亚、中东欧和独联体地区相对较少;(2)TBT每提高1个百分点,我国向“一带一路”国家的农产品出口额将减少0.003个百分点。建议建立“一带一路”农产品TBT数据库,推进农产品技术标准互认和磋商机制,引导企业内外兼修积极应对TBT。     

黄芪多糖提高鸡抗氧化作用对免疫功能的影响

本实验观察了黄芪多糖 (APS)对正常雏鸡血清中GSH -Px、SOD活性及MDA含量的影响。在不同日龄 (5d、 14d、 2 5d)、不同APS剂量 (0、 2 5、 5、 10mg/只 )水平下 ,以点眼滴鼻、皮下注射、肌肉注射的不同给药方式使用APS后 ,各试验组血清GSH -Px、SOD活性均表现显著升高 (p <0 0 5 ) ,MDA含量均表现显著降低 (p <0 0 5 )。表明APS可提高鸡的抗氧化作用 ,提示APS可通过增强免疫器官中GSH -Px、SOD活性提高免疫防御和免疫监视。     

森林空气负离子及其主要影响因子的研究进展

空气负离子被称为"空气维生素和生长素",对人体健康十分有益.随着森林旅游事业的蓬勃发展,森林空气负离子的研究逐步成为热点问题之一.本文从森林空气负离子的概念、产生机理、影响森林空气负离子的主要环境因子、空气负离子在森林旅游区的应用等方面进行了综述,探讨了未来空气负离子研究与开发的重点方面.目的是促进森林空气负离子的研究与发展.     

人工增雨指挥实时显示平台的设计和实现

随着气候变暖趋势日益明显,人工增雨作业在开发云水资源以及防灾减灾中起到了越来越重要的作用。国家投入大量资源装备增雨作业的同时也给人工影响天气工作提出了新的考验,即安全、科学、高效的开展人工增雨作业。为了提高辽宁省人工影响天气工作的科学性、管理的规范性,建立了人工增雨实时显示平台。平台提供实时的雷达、卫星、数值预报、飞机监控等多种手段,有效地对当前天气变化进行监测并提供警报,满足了人工增雨作业科学决策、合理规划、安全指挥等方面提出的要求。     

土壤进气值和发泡点测定方法的研究

应用土壤电导率与基模吸力的关系,判断和测定了土壤的进气值,采用改进后的砂型漏斗装置测定了土壤的发泡点。对脱水过程中3个不同剖面层次土壤进气值和发泡点的测定结果表明,耕作表层(A p)土壤的进气值和发泡点分别为1.343和5.880 kPa;淋溶淀积过渡层(AB)土壤的进气值和发泡点分别为2.597和4.116kPa;埋藏表层(A b)土壤的进气值和发泡点分别为0.451和6.076 kPa。由此可见,土壤的进气值与发泡点的数值明显不同,进气值与发泡点是2个不同的概念。     

雷电资料在一次强雷暴天气分析中的应用

利用山东省雷电资料配合多普勒雷达多种产品(如基本反射率、径向速度、垂直累积液态含水量等)回波图像及自动站、Micaps资料,采用统计和对比分析的方法,对2008年8月26日青岛地区的雷暴天气过程进行分析,找出闪电活动与雷达强度回波及降水的关系。结果表明,闪电发生频数较雷达回波强度在时间序列上有一定的超前性;在雷达回波发展的不同阶段,闪电发生的位置与雷达强回波位置大多相同,有时偏离;降水回波辐合区,闪电活动相对频繁,这对雷暴等强对流天气过程预警工作有一定的参考价值。