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.     

Toll-like receptor signaling pathways

Members of the Toll-like receptor (TLR) family recognize conserved microbial structures, such as bacterial lipopolysaccharide and viral double-stranded RNA, and activate signaling pathways that result in immune responses against microbial infections. All TLRs activate MyD88-dependent pathways to induce a core set of stereotyped responses, such as inflammation. However, individual TLRs can also induce immune responses that are tailored to a given microbial infection. Thus, these receptors are involved in both innate and adaptive immune responses. The mechanisms and components of these varied responses are only partly understood. Given the importance of TLRs in host defense, dissection of the pathways they activate has become an important emerging research focus. TLRs and their pathways are numerous; Science's Signal Transduction Knowledge Environment's TLR Connections Map provides an immediate, clear overview of the known components and relations of this complex system.     

Hemolin: an insect-immune protein belonging to the immunoglobulin superfamily

Insects have an efficient defense system against infections. Their antibacterial immune proteins have been well characterized. However, the molecular mechanisms by which insects recognize foreignness are not yet known. Data are presented showing that hemolin (previously named P4), a bacteria-inducible hemolymph protein of the giant silk moth Hyalophora cecropia, belongs to the immunoglobulin superfamily. Functional analyses indicate that hemolin is one of the first hemolymph components to bind to the bacterial surface, taking part in a protein complex formation that is likely to initiate the immune response.     

RNA silencing: the genome's immune system

Genomes are databases sensitive to invasion by viruses. In recent years, a defense mechanism has been discovered, which turns out to be conserved among eukaryotes. The system can be compared to the immune system in several ways: It has specificity against foreign elements and the ability to amplify and raise a massive response against an invading nucleic acid. The latter property is beginning to be understood at the molecular level.     

试论知识产品生产过程中的社会关系

现代社会生产过程不仅是一个物质产品的生产、分配、交换、消费的过程，而且是一个知识产品的生产、分配、传播、应用的过程:不仅存在着人与人之问在物质产品的生产、分配、交换、消费过程中所形成的社会关系，而且存在着人与人之间在知识产品的生产、分配、传播、应用过程中所形成的社会关系。随着我国社会主义市场经济的发展，人们在知识产品生产过程中所形成的社会关系，将由计划经济体制下的无偿性、问接性和无利性，向市场经济体制下的有偿性、直接性和互利性的方向转变。     

Autoimmune diseases: the failure of self tolerance

The ability to discriminate between self and nonself antigens is vital to the functioning of the immune system as a specific defense against invading microorganisms. Failure of the immune system to "tolerate" self tissues can result in pathological autoimmune states leading to debilitating illness and sometimes death. The induction of autoimmunity involves genetic and environmental factors that have focused the attention of researchers on the trimolecular complex formed by major histocompatibility complex molecules, antigen, and T cell receptors. Detailed molecular characterization of these components points to potential strategies for disease intervention.     

挥发性有机化合物在植物适应胁迫及生理生态中的作用

挥发性有机化合物(volatile organic compounds,VOCs)是具有低分子量和高蒸气压的亲脂性液体。按来源划分,VOCs可分为人为源和植物源,而植物源是全球大气中VOCs的最大来源。植物VOCs释放受生物和非生物因素影响,它们在大气化学反应、人体健康和植物生理生态中具有重要作用。然而,对于植物VOCs释放受复合环境条件的影响及在生理生态方面的作用尚缺乏全面了解。本研究概述了植物VOCs的合成途径,重点阐述了单一及复合环境因素对VOCs种类及释放量的影响,同时归纳了VOCs在生理生态方面的作用。发现:植物VOCs合成途径已经明确,但其调控的分子机制有待进一步探究。昆虫啃食、高温、干旱、高二氧化碳浓度可降低组成型VOCs (如异戊二烯)释放,增加储存型VOCs (如蒎烯、柠檬烯)释放,同时诱导新的化合物(如绿叶挥发物, GLVs)合成并释放;复合环境对VOCs释放影响是复杂的,有待进一步探索。VOCs在植物防御食草动物或吸引食草动物天敌、介导植物间信号转导、抗氧化、抗旱和增强植物耐热性等方面发挥作用,未来将探究植物VOCs在生态系统中的更多作用。参96     

防崩岗护水土护坡技术应用研究

防崩岗护水土网草护坡是一种新型结构体系。通过介绍其结构体系特征及其保护水土流失的工作原理，来描述其结构组成，上中下3部分的功能和构造。提出了现阶段绳网护坡结构体系所承受的外部荷载设计计算方法，现阶段应使用的规范标准和护坡绳网的设计。建立了用护坡上桩的抗拔力来平衡体系外部荷载的计算模型，使其与土坡紧密结合，形成完整的结构体系，保证该体系内力与外部荷载的平衡。通过介绍网草护坡设计施工流程，阐述不同坡度护坡的设计施工方法、基本内容和应用范围，提及使用本方法在施工上可能遇到的问题和处理措施。用经济指标对比来展示该型护坡相对传统做法表现在设计、施工上的3大优势，体现该护坡所具有的明显造价优势、适用性优势和生态优势。     

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。     

玉米虫害诱导基因启动子在拟南芥中的活性分析

植物在感知到虫害信号后会经过复杂的转录调控,开启防御基因的表达。这一过程大多受到茉莉酸信号途径的调控,现有的相关研究主要集中在双子叶模式植物拟南芥中,在单子叶植物玉米中是否具有相似的转录调控模式目前尚不清楚。为了探索这一问题,从被玉米螟咬食和150 μmol/L JA处理12 h的RNAseq玉米文库中获得两个同时受诱导的基因,Zm281和ZmPal,重点对其启动子的诱导活性进行了分析。结果表明,这两个玉米启动子在未受JA处理的拟南芥中不能启动GUS报告基因的表达,但是在茉莉酸诱导后GUS报告基因受到强烈诱导,且在各组织器官中均有表达。该结果表明受虫咬后诱导表达的基因同时受JA的诱导,可为研究JA诱导虫害应答的分子机理奠定基础。     

Application of a web-based remote agro-ecological monitoring system for observing spatial distribution and dynamics of Bactrocera dorsalis in fruit orchards

Improving fruit farm profitability through integrated pest management (IPM) programs is always an important issue to modern agriculture systems. In order to enhance IPM programs against Bactrocera dorsalis, an automatic infield monitoring system is required to efficiently capture long-term and up-to-the-minute environmental fluctuations in a fruit farm. In this study, a remote agro-ecological monitoring system built upon wireless sensor networks has been developed to provide precision agriculture (PA) services with large-scale, long-distance, long-term, scalable, and real-time infield data collection capabilities. Historical data with spatial information is available through a web-based decision support program built upon a database. Pest population forecast results are also provided so that farmers and government officials would be able to accurately respond to infield variations. Compared with the previous version of the system, various useful functions have been added into the system, and its accuracy has been improved when measuring different parameters in the field. The system could provide a valuable framework for farmers and pest control officials to analyze the relations between population dynamics of the fruit fly and meteorological events. Based on the analysis, a better insect pest risk assessment and accurate decision-making strategy can be made as an aid to PA against B. dorsalis.     

Improving the health of the global poor

We analyzed the technical basis for a major global program to reduce disease among the poor. Effective interventions exist against the few diseases which most account for excess mortality among the poor. Achieving high coverage of effective interventions requires a well-functioning health system, as well as overcoming a set of financial and nonfinancial constraints. The annual incremental cost would be between $40 billion and $52 billion by 2015 in 83 low-income and sub-Saharan African countries. Such a program is feasible and would avoid millions of child, maternal, and adult deaths annually in poor countries.     

植物系统获得性抗性研究进展

植物系统获得性抗性(Systemic Acquired Resistance,SAR)是一种能够诱导植物持续抵御病原微生物侵害的一种防御机制。SAR需要信号分子水杨酸(Salicylic Acid,SA)参与,并与能够提高抗性的病程相关蛋白(PR)的积累有关。通过对模式植物拟南芥的研究发现,异分支酸合成酶途径是合成SA的主要途径。正调控因子NPR1与转录因子TGA相互作用,诱导防卫基因表达,进而激发SAR反应。最新研究表明,脂质分子有可能是SAR反应中的移动信号分子。这些研究结果有助于进一步了解SAR反应。     

Editing at the crossroad of innate and adaptive immunity

Genetic information can be altered through the enzymatic modification of nucleotide sequences. This process, known as editing, was originally identified in the mitochondrial RNA of trypanosomes and later found to condition events as diverse as neurotransmission and lipid metabolism in mammals. Recent evidence reveals that editing enzymes may fulfill one of their most essential roles in the defense against infectious agents: first, as the mediators of antibody diversification, a step crucial for building adaptive immunity, and second, as potent intracellular poisons for the replication of viruses. Exciting questions are raised, which take us to the depth of the intimate relations between vertebrates and the microbial underworld.     

苏丹管道沿线膨胀土的危害性分析

介绍了苏丹黑格里格油田至苏丹港长输原油管道沿线自然概况,研究了管道沿线膨胀土的分布规律及工程特性,给出了塑性指数、体积变化、膨胀压力和膨胀潜势的关系及苏丹管道膨胀土的主要物理力学性质指标统计结果,指出要充分认识膨胀土对管道的潜在危害性,并提出了具体设计和施工措施。     

Expression Comparisons of Pathogenesis-Related (PR) Genes in Wheat in Response to Infection/Infestation by Fusarium,Yellow dwarf virus (YDV) Aphid-Transmitted and Hessian Fly

Expression profiles of ten pathogenesis-related (PR) genes during plant defense against Fusarium, Yellow dwarf virus (YDV) aphid-transmitted and Hessian fly (Hf) were compared temporally in both resistant and susceptible genotypes following pathogen infection or insect infestation. Quantitative real-time PCR (qRT-PCR) revealed that PR1, PR2, PR3, PR5, PR6, PR8, PR9, and PR15 appeared to be induced or suppressed independently in response to Fusarium, YDV aphid-transmitted or Hf during the interactions. The PR gene(s) essential to defense against one organism may play little or no role in defense against another pathogen or pest, suggesting the alternative mechanisms may be involved in different interactions of wheat-Fusarium, wheat-YDV aphid-transmitted and wheat-Hf. However, strong up- or down-regulation of PR12 and PR14 encoding low molecular membrane acting protein, defensin and lipid transfer protein (LTP), respectively, had been detected after either pathogen infection or insect infestation, therefore showed broad responses to pathogens and insects. It was postulated that low molecular proteins such as defensins and LTPs might play a role in the early stages of pathogenesis in the signaling process that informs plants about the attack from biotic stresses. In addition, a synergistic action between different PR genes might exist in plants to defense certain pathogens and insects on the basis of comprehensive expression profiling of various pathogenesis-related genes revealed by qRT-PCR in this study.     

二维工程图形中相切关系分析及计算机编码方法

相切约束从位置关系上来说是一种较复杂的约束，多数相切约束存在多解情况，从多解中确定出和原来图形相符的解是图形参数化系统能否正确进行尺寸驱动的关键。为此，在深入研究二维工程图形中常见相切位置关系的基础上，结合矢量叉积的概念，给出了一种确定图元相切位置关系的方法。     

几丁寡糖在木霉菌生物防治中的作用

木霉菌是重要的植物病害生防菌,在与植物病原真菌的拮抗过程中可产生一种特殊的化合物——几丁寡糖,几丁寡糖在木霉菌生防中具有多种生物功能。从真菌细胞壁和节肢动物外骨胳中分离的几丁寡糖,可充当化学激发子、诱导植物产生抗性、激发植物的防御系统、提高植物的抗病性。     

Buckminsterfullerane: the inside story

The stereoisomers of fully reduced buckminsterfullerene C(60)H(60) have been investigated with the molecular mechanics program MM3. Although it might be expected that chemical reduction would deliver all of the hydrogens to the outside, the symmetric structure produced in this way is predicted to be highly strained. Moving just one hydrogen to the inside is predicted to decrease the energy by 53 kilocalories (kcal) per mole. Putting additional hydrogens on the inside further lowers the predicted energy (depending on the steric relations between them). The miniimum energy isomer is predicted to have ten hydrogens inside with C(1) symmetry and to have an energy 400 kcal/mol less than that of the all-outside isomer. These results suggest that a process which could achieve isomerization would produce a mixture of isomers, most of which with ten hydrogens on the inside.     

Adaptability of the u.s. Industrial relations system

An industrial relations system describes the basic values, laws, institutions, and organizational practices that govern employment relationships. To be effective, an industrial relations system must be well matched to its economic and social environment and able to meet the strategic needs of employers, the workforce, and the larger society. The current state of American industrial relations is assessed against these criteria. The general proposition advanced is that the U.S. system of industrial relations that grew out of the New Deal labor legislation of the 1930s performed effectively from the 1940s through the 1960s. Pressures for change on the system began to build through the 1970s because of changes in the economic and technological environment and in the strategic behavior and needs of the parties. These pressures erupted in the early 1980s to produce a period of experimentation and fundamental change in union-management relations. The critical question in industrial relations today is whether the process of adaptation will be sustained and expanded to cover a broader range of employment relationships.