层状介质中三维物体重构的对比源反演算法

对比源反演（CSI）算法将反演问题转化为求解成本泛函的极小值问题,从而形成重构对比源和对比度的迭代序列。开发了一种三维CSI算法对层状介质中的三维物体进行重构,该算法是对二维对比源反演算法的推广。该算法无须正演计算,亦无须人为地选择正则化参数,反演过程更稳定。CSI的每一次迭代过程均采用快速Fourier变换技术计算并矢Green函数算子及其共轭算子,确保了该算法在三维层状介质情况下的高效率。复杂模型的反演结果说明,CSI算法对重构层状介质中的任意三维异常体是非常有效的。     

有限单元法 并行稀疏静力学和本征值求解

有限单元法（FEM）及其软件是求解大型工程应用的最有效工具之一。在这类应用问题中，有效的方程和本征值求解器扮演着至关重要的角色。稀疏矩阵及其求解技术已经足够成熟并在商用软件中实现。然而，截至目前，关于稀疏系数方程求解、Lanczos域分解或FEM并行计算的详细介绍的书籍尚不多见。     

Potassium conductances in hippocampal neurons blocked by excitatory amino-acid transmitters

Excitatory amino acids mediate fast synaptic transmission in the central nervous system through the activation of at least three distinct ionotropic receptors: N-methyl-D-aspartate (NMDA), the alpha-amino-3-hydroxy-5-methyl-isoxasole-4-propionate (AMPA)/quisqualate (QUIS) and the kainate subtypes (for reviews, see refs 1, 2). They also activate the additional QUIS 'metabotropic' receptor (sensitive to trans-1-amino-cyclopentyl-1,3-dicarboxylate, ACPD) linked to inositol phospholipid metabolism. We have used hippocampal slice cultures to study the electrophysiological consequences of the metabotropic response. We find that activation of an ACPD-sensitive QUIS receptor produces a 'slow' excitation of CA3 pyramidal cells, resulting from depression of a Ca2(+)-dependent K+ current and a voltage-gated K+ current. Combined voltage-clamp and microfluorometric recordings show that, although these receptors can trigger an increase in intracellular Ca2+ concentration, suppression of K+ currents is independent of changes in intracellular Ca2+. These effects closely resemble those induced by activating muscarinic acetylcholine receptors in the same neurons and suggest that excitatory amino acids not only act as fast ionotropic transmitters but also as slow neuromodulatory transmitters.     

Radiation hybrid map of the mouse genome.

Radiation hybrid (RH) maps are a useful tool for genome analysis, providing a direct method for localizing genes and anchoring physical maps and genomic sequence along chromosomes. The construction of a comprehensive RH map for the human genome has resulted in gene maps reflecting the location of more than 30,000 human genes. Here we report the first comprehensive RH map of the mouse genome. The map contains 2,486 loci screened against an RH panel of 93 cell lines. Most loci (93%) are simple sequence length polymorphisms (SSLPs) taken from the mouse genetic map, thereby providing direct integration between these two key maps. We performed RH mapping by a new and efficient approach in which we replaced traditional gel- or hybridization-based assays by a homogeneous 5'-nuclease assays involving a single common probe for all genetic markers. The map provides essentially complete connectivity and coverage across the genome, and good resolution for ordering loci, with 1 centiRay (cR) corresponding to an average of approximately 100 kb. The RH map, together with an accompanying World-Wide Web server, makes it possible for any investigator to rapidly localize sequences in the mouse genome. Together with the previously constructed genetic map and a YAC-based physical map reported in a companion paper, the fundamental maps required for mouse genomics are now available.     

VRM动态响应特性的研究

随着负载运算性能的提高,对供电的开关变换器电压调节模块(Voltage Regulator Module,VRM)提出了越来越高的要求,快速的负载响应性能就是被高度关注的性能之一.本文分析了影响VRM动态特性的因素,分类介绍了目前用于提高负载动态响应特性的方法,并对各类方法的优点与缺点进行论述.     

Induction of formation of presynaptic terminals in neuroblastoma cells by synapsin IIb

The synapsins are a family of closely related phosphoproteins (termed synapsins Ia, Ib, IIa and IIb) associated with synaptic vesicles and implicated in the short-term regulation of neurotransmitter release from nerve endings. During development, expression of the synapsins correlates temporally with synapse formation, but there has been no direct evidence that they are involved in synaptogenesis. Here we report that overexpression of synapsin IIb in the neuroblastoma x glioma hybrid clonal cell line NG108-15 leads, during cell differentiation, to marked increases in the number of neuritic varicosities and in the numbers of small clear vesicles and large dense core vesicles per varicosity, as well as to the appearance of synapse-like cell-cell contacts. Thus, synapsin IIb may be involved in the regulation of synapse formation and, as a result, in long-term neuronal signalling.     

略谈寓英美文化教育于英语教学

英语语言的学习离不开对英美文化的了解。本文主要从文化与语言的关系方面探讨寓英美文化教育于英语教学,即英美文化与词汇教学、听说教学、阅读教学和写作教学的关系。     

浅析城市水资源管理及利用

针对城市水环境污染严重、城市水利设施不完善、水资源管理缺乏经济学观念的状况，提出一系列强化城市水资源管理及利用的措施。