Intraclonal generation of antibody mutants in germinal centres

The generation and selection of somatic antibody mutants are key elements of acquired immunity, essential for the affinity maturation of antibody responses dependent on T cells. The mutants are generated through a mechanism that introduces point mutations at high rate into rearranged variable (V) region genes in the course of cell proliferation. Their appearance coincides with the generation of germinal centres, which are characterized by oligoclonal B-cell proliferation and have been suggested to be the microenvironment in which antibody mutants are generated. We report here direct evidence for this hypothesis. Rearranged V-region genes were amplified from the genomic DNA of cells picked from individual germinal centres. The sequence analysis of these genes revealed that most represent cells of distinct B-cell clones which expanded locally, generating somatic antibody mutants at high rate. By contrast, antigen-induced proliferation of B cells at another site, periarteriolar lymphocyte sheath-associated foci, was not associated with somatic hypermutation.     

冷轧钢带表面缺陷在线检测及系统的计算机接口

讨论了一种冷轧钢带表面缺陷在线检测系统的基本组成和原理，该系统能测量钢带的宽度，检测边裂、孔洞和重皮等缺陷。研究了采用存储器地址映像技术和双体ＲＡＭ总线切换技术设计的计算机接口，该接口能使数据的计算机输入和处理并行工作，省去了数据输入占用ＣＰＵ的时间，解决了实时检测系统高速数据的计算机输入和处理存在的时间冲突的难题。     

一种评价自动目标检测算法性能的方法

提出一种自动目标检测算法性能的评价方法，设计了一种实景目标背景图像合成方法，由此可以得到满足测试目标检测算法性能的要求且度量参数调整方便的测试图像集，确定了１６个图像质量度量指标，建立了性能评价的响应函数模型，采用因子分析、多元相关回归分析和Ｌｏｇｉｓｔｉｃ回归分析方法，研究算法性能与图像度量的统计关系，实验表明，所提出的目标检测算法性能评价方法是合理的。     

Regulation of p34CDC28 tyrosine phosphorylation is not required for entry into mitosis in S. cerevisiae.

Progression from G2 to M phase in eukaryotes requires activation of a protein kinase composed of p34cdc2/CDC28 associated with G1-specific cyclins. In some organisms the activation of the kinase at the G2/M boundary is due to dephosphorylation of a highly conserved tyrosine residue at position 15 (Y15) of the cdc2 protein. Here we report that in the budding yeast Saccharomyces cerevisiae, p34CDC28 also undergoes cell-cycle regulated dephosphorylation on an equivalent tyrosine residue (Y19). However, in contrast to previous observations in S. pombe, Xenopus and mammalian cells, dephosphorylation of Y19 is not required for the activation of the CDC28/cyclin kinase. Furthermore, mutation of this tyrosine residue does not affect dependence of mitosis on DNA synthesis nor does it abolish G2 arrest induced by DNA damage. Our data imply that regulated phosphorylation of this tyrosine residue is not the 'universal' means by which the onset of mitosis is determined. We propose that there are other unidentified controls that regulate entry into mitosis.     

FMS建模和形式化验证

提出了一种FMS的建模方法,此方法是基于时间自动机模型。运用模型检查工具UPPAAL来进行建模,仿真和验证。由于时间的因素被考虑到建模方法中,因此FMS的调度和控制问题可以被集成到这个模型中。在系统的行为被控制的同时,可以保证系统的性能指标。从而最优调度和最优控制可以得到检查和验证。     

The Theory of Adaptation of the Nervous System

The explanation and simulation of the natural and artificial intelligence are the central goals of the studies of Neuroscience, Psychology, Artificial Intelligence and Cognitive Science. This paper first gives an introduction to the core topics and approaches in the study. Then, GAF--a general adaptive framework for neural system is proposed. Interdisciplinary discussions around the adaptation of the human nervous system are presented. Rules describing the theory of adaptation of the nervous system are provided.     

Hsp90 chaperones protein folding in vitro.

The heat-shock protein Hsp90 is the most abundant constitutively expressed stress protein in the cytosol of eukaryotic cells, where it participates in the maturation of other proteins, modulation of protein activity in the case of hormone-free steroid receptors, and intracellular transport of some newly synthesized kinases. A feature of all these processes could be their dependence on the formation of protein structure. If Hsp90 is a molecular chaperone involved in maintaining a certain subset of cellular proteins in an inactive form, it should also be able to recognize and bind non-native proteins, thereby influencing their folding to the native state. Here we investigate whether Hsp90 can influence protein folding in vitro and show that Hsp90 suppresses the formation of protein aggregates by binding to the target proteins at a stoichiometry of one Hsp90 dimer to one or two substrate molecule(s). Furthermore, the yield of correctly folded and functional protein is increased significantly. The action of Hsp90 does not depend on the presence of nucleoside triphosphates, so it may be that Hsp90 uses a novel molecular mechanism to assist protein folding in vivo.