华南中小流域设计暴雨洪水同频率检验与重现水平推算

暴雨洪水同频率假定是否成立和暴雨洪水遭遇概率分布是中小流域设计洪水计算的依据,为检验其合理性,采用鉴江上游曹江流域典型强降水流域1967—2013年逐时暴雨洪水观测资料,分析了华南中小流域最大面雨量R和对应场次最大洪峰流量Q的边缘分布和联合分布的遭遇概率,并推算其设计重现水平。研究结果表明：暴雨和洪水同频遭遇概率较小;对于特定设计频率,洪峰流量与流域面雨量的遭遇概率随流域面雨量增大而增大;流域面雨量和洪峰流量的遭遇条件概率显示存在着多种防洪风险管理选择;相对于“或”联合重现期和“且”重现期,二次重现期更准确地反映R-Q组合的风险率。     

提高高频晶闸管di/dt耐量的研究

为提高高频晶闸管的动态指标和高频性能，通过实验分析和理论推导，研究了工艺参数和设计参数对高频晶闸管ｄｉ／ｄｔ耐量的影响。实验结果表明：较低的一扩浓度，较薄的基区宽度以及用高能电子辐照控制少子寿命，有利于提高ｄｉ／ｄｔ耐量。通过对相同工艺三种不同阴极图形的８００Ａ、１０ｋＨｚ高频晶闸管ｄｉ／ｄｔ的研究，论证了合理确定辅助晶闸管面积对提高ｄｉ／ｄｔ的重要性，并指出，在大面积高频晶闸管中设计二级放大门极，有利于提高ｄｉ／ｄｔ耐量。     

一类不可微多目标规划的 Kuhn-Tucker 充分条件

对局部Ｌｉｐｓｃｈｉｔｚ函数引进了广义凸性的概念，讨论了一类不可微多目标规划的ＫｕｈｎＴｕｃｋｅｒ最优充分性条件．     

比较两组样本均值的随机加权法

利用随机加权法给出了两组相互独立的样本均值比较的假设检验,这种检验并不要求被检样本分布一定是正态的,同时证明在适当条件下所用的估计比通常的正态逼近具有更高的精度。     

一种新的基于假设的自然推理系统

本文在介绍自动定理证明的历史和分析自然推理研究的现有成果的基础上,提出了用以实现启发式自然推理系统HNDS的确定性推理算法。并设计了用作推理基本手段的假设机制。本系统采用知识库系统的软件结构,面向标准形式的命题逻辑和一阶谓词逻辑,对系统定理能给出清晰的类人证文过程。HNDS系统基于的推理算法理论上是合理的和完备的,这主要因为系统结合了自然推理与消解原理,并首创了量词逐层Skolem化的策略。     

一种预测蛋白质二级结构的简便方法

以“广义摆动假说”为理论基础,从基因密码子的第二位碱基入手,把氨基酸——“词”简并成核苷酸——“语言”,可直接预测蛋白质的二级结构,从对一些蛋白质的预测结果可见,准确度与Chou-Fasman法相近。     

Alzheimer's disease: fundamental and therapeutic aspects

Alzheimer's disease is the most common type of progressive and debilitating dementia affecting aged people. In some early — as well as late-onset familial cases, a genetic linkage with chromosomes 14, 21 (early-onset) or 19 (late-onset) has been indicated. Furthermore, a direct or indirect role has been attributed to normal or structurally altered amyloid -protein (concentrated in senile plaques) and/or excessively phosphorylated tau protein (located in neurofibrillary tangles). Degeneration of cholinergic neurons and concomitant impairment of cortical and hippocampal neurotransmission lead to cognitive and memory deficits. Several compounds are being tested in attempts to prevent and/or cure Alzheimer's disease, including tacrine, which has very modest efficacy in a sub-group of patients, and new acetylcholinesterase inhibitors. Pilot experiments have also been launched using nerve growth factor (NGF) to prevent or stabilize the processes of cholinergic pathway degeneration. Alternatively, antioxidants, free radical scavengers and/or non steroidal anti-inflammatory agents may be screened as potential therapies for neurodegenerative diseases induced by multiple endogenous and/or exogenous factors. The recent use of transgenic mice, in parallel with other genetic, biochemical and neurobiological systems, in vivo and/or in vitro (cell cultures), should accelerate the discovery and development of specific drugs for the treatment of Alzheimer's disease.     

Genetic and molecular approaches to synthesis and action of the yeast killer toxin

Summary The K1 killer toxin ofSaccharomyces cerevisiae is a secreted, virally-coded protein lethal to sensitive yeasts. Killer yeasts are immune to the toxin they produce. This killer system has been extensively examined from genetic and molecular perspectives. Here we review the biology of killer yeasts, and examine the synthesis and action of the protein toxin and the immunity component. We summarise the structure of the toxin precursor gene and its protein products, outline the proteolytic processing of the toxin subunits from the precursor, and their passage through the yeast secretory pathway. We then discuss the mode of action of the toxin, its lectin-like interaction with a cell wall glucan, and its probable role in forming channels in the yeast plasma membrane. In addition we describe models of how a toxin precursor species functions as the immunity component, probably by interfering with channel formation. We conclude with a review of the functional domains of the toxin structural gene as determined by site-directed mutagenesis. This work has identified regions associated with glucan binding, toxin activity, and immunity.     

Cubature Kalman probability hypothesis density filter based on multi-sensor consistency fusion①

The GM-PHD framework as recursion realization of PHD filter is extensively applied to multi-target tracking system .A new idea of improving the estimation precision of time-varying multi-target in non-linear system is proposed due to the advantage of computation efficiency in this paper .First, a novel cubature Kalman probability hypothesis density filter is designed for single sensor measure -ment system under the Gaussian mixture framework .Second , the consistency fusion strategy for multi-sensor measurement is proposed through constructing consistency matrix .Furthermore, to take the advantage of consistency fusion strategy , fused measurement is introduced in the update step of cubature Kalman probability hypothesis density filter to replace the single-sensor measurement .Then a cubature Kalman probability hypothesis density filter based on multi-sensor consistency fusion is proposed .Capabilily of the proposed algorithm is illustrated through simulation scenario of multi-sen-sor multi-target tracking .     

重组白细胞介素-13及其受体对小鼠胚胎成纤维细胞增殖及表型转化的影响

将常规培养的NIH3T3细胞分为实验组和对照组,实验组加入80μg/L IL-13,作用24h后进行以下实验:使用RT-PCR技术检测NIH3T3细胞中IL-13Rα1、IL-13Rα2及α-SMA基因的表达;使用MTT法检测NIH3T3细胞的增殖率.研究结果表明:实验组NIH3T3细胞,胞体呈梭型,突起生长迅速,相互交织成网状,与对照组相比形态发生了明显的改变;MTT法测定显示,实验组NIH3T3细胞的增殖率与对照组相比显著增加,差异显著(P0.01);RT-PCR检测IL-13Rα2及α-SMA基因的表达量均显著增加,而IL-13Rα1表达量变化不大.本研究表明IL-13Rα2在成纤维细胞上的表达与其增殖和转型具有直接的相关性,IL-13可直接作用于成纤维细胞并可能以IL-13Rα2为起点发挥致肺纤维化作用.