Protein folds: molecular systematics in three dimensions

Advances in methods of structure determination have led to the accumulation of large amounts of protein structural data. Some 500 distinct protein folds have now been characterized, representing one-third of all globular folds that exist. The range of known structural types and the relatively large fraction of the protein universe that has already been sampled have greatly facilitated the discovery of some unifying principles governing protein structure and evolutionary relationships. These include a highly skewed distribution of topological arrangements of secondary-structure elements that favors a few very common connectivities and a highly skewed distribution in the capacity of folds to accommodate unrelated sequences. These and other observations suggest that the number of folds is far fewer than the number of genes, and that the fold universe is dominated by a small number of giant attractors that accommodate large numbers of unrelated sequences. Thus all basic protein folds will likely be determined in the near future, laying the foundation for a comprehensive understanding of the biochemical and cellular functions of whole organisms.     

塔里木盆地前震旦-石炭纪构造与地层组合特征

通过对塔里木盆地前震旦-石炭纪构造演化与地层组合特征的分析研究,将该盆地构造和地层系统划分为2大组合系统5个构造-地层组合.前震旦系为混合片麻岩、浅变质岩组成的地台基底,震旦纪发生板内裂陷形成坳拉槽,早寒武世-奥陶纪和石炭纪是盆地两次大的海侵期,沉积了富含烃类的碳酸盐岩建造,志留-泥盆纪为克拉通边缘隆升阶段,发育浅海相碎屑岩及碳酸盐岩建造.     

评述西方文化进化论的新进展

作为一种文化唯物主义理论,在西方流行的“文化进化论”中有一些成分值得中国地域文化研究加以批判借鉴。其中,“文化生态学”和“文化进化能量法”以及“新进化论”等学说,均在一定的程度上与唯物史观有所契合,对我们解剖中国地域文化的异同提供了某种基本视角。     

Notable diversity in hemoglobin expression patterns among species of the deep-sea clam, <Emphasis Type="Italic">Calyptogena</Emphasis>

The deep-sea clams Calyptogena nautilei and C. tsubasa, which live in the cold-seep area at a depth of 3570 m in the Nankai Trough, Japan, have abundant hemoglobins (Hbs) in erythrocytes, similar to other Calyptogena species. We determined the cDNA-derived amino acid sequences of Hbs from two Calyptogena species. C. tsubasa was found to contain two dimeric Hbs, Hb I consisting of 145 amino acid residues and Hb II with 137 residues, similar to known Hbs from C. soyoae and C. kaikoi. Sequence identity was over 90% among the orthologous chains of Calyptogena Hbs. On the other hand, surprisingly, C. nautilei contained two monomeric Hbs, Hb III containing 141 residues and Hb IV with 134 residues. In addition, Hbs III and IV showed only 33–42% sequence identity with Hbs I and II from other Calyptogena species. The distal (E7) histidine, one of the functionally important residues of the heme protein, is replaced by glutamine in all Hb chains of Calyptogena species. A phylogenetic analysis indicated that C. nautilei Hb III is closer to Hb I from other Calyptogena species. We suppose that a Hb gene was duplicated at least three times in an immediate ancestor of Calyptogena and, presumably depending on physiological conditions different Hb sets are being expressed: dimeric Hbs I and II in C. soyoae, C. kaikoi and C. tsubasa, and monomeric Hbs III and IV in C. nautilei. Received 13 May 2003; received after revision 5 June 2003; accepted 12 June 2003     

Power-Based Arbitrary Decisional Actions in the Resolution of MIS Project Issues: A Project Manager's Action Research Perspective

As a management information systems (MIS) project manager and an action researcher, the author examined, over time, the influence on information system development (ISD) of the informal sociopolitical organizational actions. The paper reports two cases of action research findings concerning the effect on ISD project implementation processes of power-based arbitrary decisional actions in bureaucratic environments. The research focused on the relationship of such unilateral actions to the interconnected subprocesses of deliberate and conscious attempts by the ISD project members to define and resolve system implementation issues. A suggested conceptual framework for the issue-resolution processes (IRP's) and obstacle-coping processes (OCP's) is based on the author's IRP/OCP-related behavioral constructs and theoretical models dealing with soft-systems issues, especially appreciative system theory and soft-systems methodology, and innovative flexible, "complementarist" (Sinn, 1998) or pluralist problem-solving approaches.     

概念组织进化:图尔明对科学理性问题的解决

现代西方科学哲学从上世纪二三十年代的逻辑经验主义向当代的自然主义与实践哲学的转变,背后实现的是对逻辑经验主义的理论预设的超越。就范导这一超越所遵循的路线和依据而言,图尔明的超前于科学哲学主流的工作占有独特地位。     

投影寻踪动态聚类模型

投影寻踪聚类模型在多因素聚类分析中被广泛应用并取得了满意的效果,然而,该模型还存在诸如密度窗宽参数取值经验确定等不足,有待改进提高.本文针对投影寻踪聚类模型的不足,首次把投影寻踪的思想和动态聚类方法结合起来构造投影指标,基于免疫进化算法,建立了投影寻踪动态聚类新模型.新模型一方面在整个运算过程中毋需人为给定参数,聚类结果客观、明确,另一方面,它还具有稳定性好、操作简便等特点.洪水分类的实际应用表明,投影寻踪动态聚类模型切实可行,取得了很好的效果,在多因素聚类分析领域具有广阔的应用前景.     

对科技创新促进产业创新的哲学探析

科技创新与产业创新二者皆具生态进化特性，科技创新促进产业创新在区域内具有其内在的一些表征：共生进化的统一性、投资的高风险性、区域产业发展的非平衡性等。科技创新在产业创新上的价值体现不仅是其本身的表现，还负荷着科学精神、科技创新文化等内在的价值作用。科技创新促进产业创新，产业创新为科技创新增活力。不断优化区域科技创新的环境与系统。提高以自主创新的核心创新能力，促进与产业创新的共生进化与优化。     

一个快速进化的microRNA家族

microRNAs(miRNAs)是长约22nt的非编码RNA,它可通过降解mRNA或抑制其翻译来调控基因。本文简要介绍了miRNAs的研究背景,阐述了通过比较近缘物种中非保守的miRNA基因来研究miRNAs分子进化的理由。我们的研究结果证实miRNA基因会受到达尔文正选择的影响,发生快速的进化。这一结果将为我们了解非蛋白编码基因的功能与进化提供崭新的视角。     

武器装备体系结构演化仿真研究

受经费和生产能力的限制,武器装备建设过程呈现渐进发展的特点。科学的建设计划方案成为实现武器装备体系结构优化的重要条件。从武器装备的体系层次出发,提出了武器装备体系结构演化仿真的概念,明确了体系结构演化仿真的使命任务及总体思路。在分析了武器装备体系演化过程的主要影响因素、确定了基本优化思路的基础上,提出了体系结构演化仿真的优化指标。最后,从顶层设计的角度提出了软件系统的功能模型。