Insecticide resistance and vector control

Insecticide resistance has been a problem in all insect groups that serve as vectors of emerging diseases. Although mechanisms by which insecticides become less effective are similar across all vector taxa, each resistance problem is potentially unique and may involve a complex pattern of resistance foci. The main defense against resistance is close surveillance of the susceptibility of vector populations. We describe the mechanisms of insecticide resistance, as well as specific instances of resistance emergence worldwide, and discuss prospects for resistance management and priorities for detection and surveillance.     

含硼钢中硼的存在形式及控制研究

南京钢铁股份有限公司在生产含硼钢S355J-3-B过程中,铸坯裂纹发生率较高。根据钢种成分,采用化学分析、拉曼光谱和场发射透射电镜等手段研究了含硼钢S355J-3-B中硼的存在形式。全硼质量分数为15×10-6,酸溶硼质量分数为9×10-6。拉曼光谱和透射电镜观察下发现了BN析出物。热力学计算表明:含硼钢的冶炼应先加Al充分脱氧后,再加入Ti脱氮,最后加入B。连铸的矫直阶段,细小的BN粒子钉扎奥氏体晶界,是铸坯表面微裂纹产生的重要原因,而Ti元素的加入对提高含硼钢的高温热塑性有利。而且提高Ti含量后,S355J-3-B铸坯裂纹发生率由10%降低到3%。     

Approaches to vector control: new and trusted. 4. Appropriate technology for vector control: impregnated bed nets, polystyrene beads and fly traps

There are social, economic and entomological problems with conventional insecticidal spraying methods for vector control. There is therefore interest in alternative technologies, especially the impregnation of bed nets with pyrethroid insecticides against malaria vectors. This method is cheap, socially acceptable and effective where bed nets are already widely used and where malaria transmission is not very intense. In holoendemic areas, and where people consider bed nets unaffordable, there are still unanswered questions. Whether pyrethroid resistance will be selected in anophelines also deserves more attention than it has so far attracted. Where Culex mosquitoes breed in confined sites such as pit latrines, the application of floating layers of polystyrene beads is a long-lasting and effective control method. There is increasing evidence that house flies are important agents in the mechanical transmission of diarrhoea due to Shigella. Simple fly traps can be an effective way of controlling house fly populations and this deserves comprehensive testing in tropical countries.     

按转子磁链定向矢量的智能控制

对按转子磁链定向的矢量控制系统进行了智能控制研究.根据矢量控制的特点,充分运用计算机丰富的逻辑判断和数值运算功能对控制系统进行设计,不仅可以实现模拟控制器的数字化,而且可以突破模拟控制器参数为定值的局限.重点介绍了根据系统的变量变化趋势来确定数字调节器参数的变化规则,同时对于各个不同的调节规律,采用不同的控制策略,使得系统具有更好的动、静态性能指标,更强的鲁棒性.最后通过仿真和实验证明了本文理论的正确性.     

交流变频矢量控制系统的自适应逆控制

针对一般矢量控制系统存在的动、静态转矩电流与磁场电流的耦合问题,在分析磁场定向偏差对系统性能影响的基础上,首次引入自适应逆控制策略的控制方案,并分析了方案的控制特点.理论分析及仿真实验表明,该控制策略可以有效地解决一般矢量控制系统存在的转矩与磁场耦合对系统性能造成的影响,提高系统动、静态性能.     

Malaria vaccine: roadblocks and possible solutions

Malaria remains the most prevalent and devastating parasitic disease worldwide. Vaccination is considered to be an approach that will complement other strategies for prevention and control of the disease in the future. In the last 10 years, intense studies aimed at the development of a malaria vaccine have provided important knowledge of the nature of the host immunological mechanisms of protection and their respective target antigens. It became well established that protective immune responses can be generated against the distinct stages of Plasmodium. However, in general, protective immune responses are directed at stage-specific antigens. The elucidation of the primary structure of these antigens made possible the generation of synthetic and recombinant proteins that are being extensively used in experimental immunizations against the infection. Today, several epitopes of limited polymorphism have been described and protective immunity can be generated by immunization with them. These epitopes are being tested as primary candidates for a subunit vaccine against malaria. Here we critically review the major roadblocks for the development of a malaria vaccine and provide some insight on how these problems are being solved.     

Computational methods in molecular diversity and combinatorial chemistry

(+)-MK-801 is known to be a specific non-competitive antagonist of N-methyl-D-aspartate (NMDA) receptors. However, besides having an anticonvulsant effect, this compound possesses a central sympathomimetic effect and an anxiolytic-like action, raising the possibility that (+)-MK-801 might affect monoamine uptake systems. To elucidate this possibility, we investigated the effects of (+)-MK-801 on monoamine transporters expressed in HEK cells. (+)-MK-801 significantly inhibited the uptake of all three monoamine transporters in a dose-dependent manner and the inhibitions were competitive with respect to monoamines. The Ki values of (+)-MK-801 on the norepinephrine, dopamine and serotonin transporters were 3.2 microM, 40 microM and 43 microM, respectively. In addition, (-)-MK-801, a less potent antagonist of NMDA receptors, also inhibited monoamine transporters with a similar potency as that of (+)-MK-801. These results clearly indicate that MK-801, a non-competitive antagonist of NMDA receptors, competitively inhibits monoamine transporters without stereoselectivity.     

变频矢量控制系统入侵检测技术

针对采用以太网控制自动化技术(EtherCAT)工业总线的感应电机交-直-交变频矢量控制系统的入侵检测技术进行了研究. 首先通过对EtherCAT总线协议进行深度解析, 结合目前为止已经发现的EtherCAT工业总线常见协议漏洞, 提取协议数据包的关键特征并构建EtherCAT总线协议入侵检测规则库, 采用三维指针链表树作为针对EtherCAT总线协议规则库的检索数据结构; 其次, 根据感应电机交-直-交变频矢量控制系统的物理模型, 进行模型参数仿真计算, 并根据仿真计算值, 构建矢量控制模型入侵特征的最小二乘支持向量机(least square support vector machine, LSSVM)分类器, 使用混沌粒子群优化(choatics particle swarm optimization, CPSO)算法对分类器的参数进行优化, 二者共同构成了CPSO-LSSVM入侵检测分类算法. 异常数据包在被分类后, 会被传递给Suricata入侵检测引擎进行精确规则匹配; 最后为该入侵检测系统搭建物理实验环境, 经过测试, 本文中的交-直-交变频矢量控制模型仿真结果动态性能良好, 与实际矢量控制系统参数的波形变化趋势相近. 通过抽取KDD Cup99测试数据集中的一部分对该入侵检测系统实施DOS攻击、R2L、U2R以及PROBING攻击行为, 验证该入侵检测系统的有效性.      

变频矢量控制系统入侵检测技术

针对采用以太网控制自动化技术(Ether CAT)工业总线的感应电机交-直-交变频矢量控制系统的入侵检测技术进行了研究.首先通过对Ether CAT总线协议进行深度解析,结合目前为止已经发现的Ether CAT工业总线常见协议漏洞,提取协议数据包的关键特征并构建Ether CAT总线协议入侵检测规则库,采用三维指针链表树作为针对Ether CAT总线协议规则库的检索数据结构;其次,根据感应电机交-直-交变频矢量控制系统的物理模型,进行模型参数仿真计算,并根据仿真计算值,构建矢量控制模型入侵特征的最小二乘支持向量机(least square support vector machine,LSSVM)分类器,使用混沌粒子群优化(choatics particle swarm optimization,CPSO)算法对分类器的参数进行优化,二者共同构成了CPSO-LSSVM入侵检测分类算法.异常数据包在被分类后,会被传递给Suricata入侵检测引擎进行精确规则匹配;最后为该入侵检测系统搭建物理实验环境,经过测试,本文中的交-直-交变频矢量控制模型仿真结果动态性能良好,与实际矢量控制系统参数的波形变化趋势相近.通过抽取KDD Cup99测试数据集中的一部分对该入侵检测系统实施DOS攻击、R2L、U2R以及PROBING攻击行为,验证该入侵检测系统的有效性.     

Two-laboratory collaborative study on identification of mycobacteria: molecular versus phenotypic methods

Previous studies have indicated that the conventional tests used for the identification of mycobacteria may (i) frequently result in erroneous identification and (ii) underestimate the diversity within the genus Mycobacterium. To address this issue in a more systematic fashion, a study comparing phenotypic and molecular methods for the identification of mycobacteria was initiated. Focus was given to isolates which were difficult to identify to species level and which yielded inconclusive results by conventional tests performed under day-to-day routine laboratory conditions. Traditional methods included growth rate, colonial morphology, pigmentation, biochemical profiles, and gas-liquid chromatography of short-chain fatty acids. Molecular identification was done by PCR-mediated partial sequence analysis of the gene encoding the 16S rRNA. A total of 34 isolates was included in this study; 13 of the isolates corresponded to established species, and 21 isolates corresponded to previously uncharacterized taxa. For five isolates, phenotypic and molecular analyses gave identical results. For five isolates, minor discrepancies were present; four isolates remained unidentified after biochemical testing. For 20 isolates, major discrepancies between traditional and molecular typing methods were observed. Retrospective analysis of the data revealed that the discrepant results were without exception due to erroneous biochemical test results or interpretations. In particular, phenotypic identification schemes were compromised with regard to the recognition of previously undescribed taxa. We conclude that molecular typing by 16S rRNA sequence determination is not only more rapid (12 to 36 h versus 4 to 8 weeks) but also more accurate than traditional typing.     

Flexibases: a way to enhance the use of molecular docking methods

Specially expanded databases containing three-dimensional structures are created to enhance the utility of docking methods to find new leads, i.e., active compounds of pharmacological interest. The expansion is based on the automatic generation of a set of maximally dissimilar conformations. The ligand receptor system of methotrexate and dihydrofolate reductase is used to demonstrate the feasibility of creating flexibases and their utility in docking studies.     

Malaria: recent immunological acquisitions and therapeutic prospects

Malaria remains one of the major health problems in many tropical countries. The asymptomatic carrier status is common and about 100% of the children in highly endemic areas have Plasmodium falciparum parasitaemia at any given time. Consequently a case definition based on the mere presence of parasites in the blood is non-informative in terms of measuring morbidity. Acquired clinical and parasitological immunity develop progressively over several years after repeated exposure to infection. Protection is acquired first again death or severe clinical disease, but protection against infection is never complete, moreover it is still not known why some infections are mild an some fatal. Although virulence markers on the parasite have not been identified with certainty, there are some indications that parasites differ in virulence. The genetic composition of human many also play a role in the defence against the parasite, so the immune mechanisms responsible for the acquired immunity remain uncertain. In fact, an infection by Plasmodium falciparum induces a variety of immune responses, including humoral and cellular, which can be specific or non-specific responses, some of which are protective, but against which the parasite has evolved effective escape measures. Vaccines has proven a most effective measure to control infectious diseases, but no consistently effective vaccine has yet developed against a human parasitic disease. A malaria vaccine aimed at disrupting the parasites life cycle at one or more of the three stages (sporozoite or pre-erythrocytic stage, asexual blood or erythrocytic stage, and sexual or sporogonic stage) might be a long-term solution.     

Features and control methods of the galvanneal furnace

The recent rapid developments in the automobile industry have demanded the extensive use of galvannealed(GA)steel sheets.In particular,the development of lightweight automobiles is putting increasingly higher requirements on the strength of GA steel sheets.The galvanneal furnace,which is used for processing galvannealed steel sheets,is typically composed of the induction heating section,holding section and fog cooling section.This paper described the structural characteristics of each component of the galvanneal furnace,and analyzed temperature control methods of the galvanneal furnace that are important for the successful production of high-strength GA steel sheets for automotive applications.     

Computation of molecular electrostatics with boundary element methods

In continuum approaches to molecular electrostatics, the boundary element method (BEM) can provide accurate solutions to the Poisson-Boltzmann equation. However, the numerical aspects of this method pose significant problems. We describe our approach, applying an alpha shape-based method to generate a high-quality mesh, which represents the shape and topology of the molecule precisely. We also describe an analytical method for mapping points from the planar mesh to their exact locations on the surface of the molecule. We demonstrate that derivative boundary integral formulation has numerical advantages over the nonderivative formulation: the well-conditioned influence matrix can be maintained without deterioration of the condition number when the number of the mesh elements scales up. Singular integrand kernels are characteristics of the BEM. Their accurate integration is an important issue. We describe variable transformations that allow accurate numerical integration. The latter is the only plausible integral evaluation method when using curve-shaped boundary elements.     

矢量控制技术在冷轧生产线中的应用

交流鼠笼式异步电机是目前冷轧生产线上最常用的传动执行电机.介绍了交流异步电机矢量控制的基本原理,针对冷轧生产线工艺控制的要求和特点,分析了传动系统基于矢量控制技术的特殊应用.工程实践证明,矢量控制技术在冷轧生产线上的应用完全满足系统控制要求.     

Obstetric risk: evaluation of existing indices and criteria

OBJECTIVES: To study the validity of the most common systems for evaluating obstetric risk in a random representative sample of pregnant Andalusian women. DESIGN: Crossover study of 1852 pregnancies of over 28 weeks and in which the women gave birth in the public hospitals of Andalusia (C.I. 95%, 7.5% accuracy). Information came from the maternity and neonatal clinical records and from a home visit after the birth. Sensitivity, specificity and predictive values of each cut suggested by the author in each system evaluated was calculated. Systems were compared with ROC curves. PARTICIPANTS: Andalusian women who gave birth in public hospitals. Measurements and main results. Obstetric risk was evaluated with the Nesbitt and Aubry (ASMI), Hobel, Coopland and IROM indices, with the criteria used in Malaga West District, and Bull's proposals for English general practitioners. The validity of the predictions was studied for premature birth, low birth-weight, the CIR, hypoxia in the new-born, pathological birth and lengthy hospital stays of mother and child. The low predictive power of the indices studied was demonstrated. The best were the Hobel, Coopland and IROM indices. The indices had greater predictive power than the referral criteria: this, appreciating the different philosophies underlying the systems which, independently of their validity, determine the number of pregnant women at risk. CONCLUSIONS: Since defining a pregnant woman as at risk is not innocuous, the research showed the importance of constructing systems, or at least validating existing ones, for the target community.