雌激素对脑缺血保护作用的分子机制

许多临床及基础研究显示雌激素对脑缺血具有保护作用, 它能通过多种途径增加缺血区的血流量, 减少再灌注损伤, 有利于残存的神经元恢复功能。本文主要从分子机制方面阐述, 雌激素能抑制缺血区肿瘤坏死因子-α(TNF-α)等炎性细胞因子及粘附分子的表达;能作用于钙通道抑制钙离子超载和兴奋性氨基酸释放;诱发BCL-2 等抗凋亡蛋白的表达, 而且各途径之间关系密不可分。明确雌激素对脑缺血保护作用的确切机制, 将更好地指导其临床应用。     

对反措中“主变断路器失灵跳各侧”做法的改进建议

对《广东省电力系统继电保护反事故措施2007版》中提出当220kV母线故障,且主变220kV侧开关失灵时,要求联跳主变各侧开关的做法进行探讨,提出了一种新的二次接线方法。     

The lysine-rich C-terminal repeats of the centromere-binding factor 5 (Cbf5) of Kluyveromyces lactis are not essential for function

The gene coding for the centromere-binding factor 5 (CBF5) of Kluyveromyces lactis has been isolated by hybridization of a Saccharomyces cerevisiae CBF5 DNA probe to a K. lactis library. The amino acid sequence of KlCbf5 is highly homologous, 88% identity, to ScCbf5, but also to the rat protein Nap57 (64% identity). The main difference between both yeast proteins and the rat protein is the presence of a lysine-rich domain with KKE/D repeats in the C-terminal part of the protein. These repeats are thought to be involved in binding of the protein to microtubules. Deletion of the KKE/D domain in KlCbf5 however, has no discernible effect on growth on rich medium, sensitivity to the microtubule-destabilizing drug benomyl or segregation of a reporter plasmid. On the other hand, insertion of two leucine residues adjacent to the KKE domain increases the loss rate of a reporter plasmid. In both yeasts complementation of a lethal CBF5 disruption with the heterologous gene results in a slight increase in benomyl sensitivity. A possible role of CBF5 in chromosome segregation will be discussed. © 1998 John Wiley & Sons, Ltd.     

A Survey on the Control Lyapunov Function and Control Barrier Function for Nonlinear-Affine Control Systems

This survey provides a brief overview on the control Lyapunov function (CLF) and control barrier function (CBF) for general nonlinear-affine control systems. The problem of control is formulated as an optimization problem where the optimal control policy is derived by solving a constrained quadratic programming (QP) problem. The CLF and CBF respectively characterize the stability objective and the safety objective for the nonlinear control systems. These objectives imply important properties including controllability, convergence, and robustness of control problems. Under this framework, optimal control corresponds to the minimal solution to a constrained QP problem. When uncertainties are explicitly considered, the setting of the CLF and CBF is proposed to study the input-to-state stability and input-to-state safety and to analyze the effect of disturbances. The recent theoretic progress and novel applications of CLF and CBF are systematically reviewed and discussed in this paper. Finally, we provide research directions that are significant for the advance of knowledge in this area.      

DOA estimation based on fourth order cumulant beamforming for nonuniform linear array of DIFAR sonobuoys

The Directional Frequency Analysis and Recording (DIFAR) sonobuoy has been widely used in underwater target localization because it can capture more information than the Low Frequency Analysis and Recording (LOFAR) omnidirectional sonobuoy. Recently, array processing for fields of DIFAR sonobuoys has attracted considerable attention in order to enhance the direction of arrival (DOA) estimation performance and accuracy. DIFAR sonobuoys may become irregularly spaced due to the deployment method and the drift experienced once deployed, resulting in a nonuniform array. In this paper, we demonstrate the fourth-order cumulant beamforming (FOC-BF) technique to estimate the DOA for a nonuniform linear array of DIFAR sonobuoys. FOC-BF was compared with the conventional beamforming (CBF) through simulation works. The results show that FOC-BF provides better spatial spectrum with lower sidelobes than CBF. Furthermore, FOC-BF provides superior DOA estimation accuracy over CBF at very low signal to noise ratios (SNR).     

基于并行Bloom过滤器组的深度数据包检测算法

针对基于软件、硬件的深度数据包检测存在处理速度慢或规则集更新困难等方面的局限性,提出一种在多核平台上基于并行Bloom过滤器组的深度数据包检测算法。算法中首先将规则集按规则的长度分组,构造一个并行Bloom过滤器组,组中每个计数式 Bloom过滤器表示特定规则长度的规则集。为了减少执行过程中的冲突概率和计算量,构造了高性能的哈希函数,然后基于多核平台的并行处理能力使用并行编程实现了该算法。理论分析和实验结果表明该算法是一种时空高效的算法。     

基于CBF的分布式元组空间叉积算法

针对分布式报文分类算法内存消耗大、可扩展性差的问题,提出分布式元组空间叉积算法。该算法采用独立域搜索引擎与树状多级聚合网络的分类结构,在聚合节点使用计数型布鲁姆过滤器(CBF)加速搜索,利用剪枝技术降低CBF内存消耗。仿真结果表明,对于 5×104条规模的9域规则库,聚合网络总内存消耗被控制在60 Kb内,该算法的查找速度达到100 Mp/s,且具有良好的可扩展性。