大肠杆菌和枯草杆菌的L-ter 到起始密码子的距离分析

基于第一ATG规则，分别对确定基因和不确定基因的L-ter到起始密码子(ATG、GTG或TTG)的距离和L-ter到起始密码子下游紧邻的ATG的距离进行统计，结果表明：L-ter到起始密码子的距离主要分布在20个氨基酸以内；在以第一ATG和第一GTG为起始密码子的基因中，L-ter到起始密码子下游紧邻的ATG是L-ter到起始密码子平均距离的4～5倍。这些可能是起始密码子的重要位置特征，也说明了少数基因以GTG起始的原因．对于不满足第一ATG、GTG规则的基因，分析了L-ter到起始密码子之间出现ATG、GTG和TTG的比率，发现大肠杆菌的不确定基因与确定基因之间有较大的差别，而枯草杆菌的差别不大．     

概率内积空间的拓扑性质及其应用

本文证明了[1]中给出的概率内积空间上的拓扑是可度量化的及其它一些良好性质     

基于内积和边界差的骨架结构提取

为提高骨架提取算法的适用性,提出一种新型的骨架提取算法.通过对对象的边界元素按照空间距离顺序标号,求出对象内部像素的边界差,由边界差得到8连通的骨架分层.为提高算法的处理速度,提出前向分层和反向跟踪两个过程的骨架细化方法,用向量差Vd和长宽比(LWR)两个参数及支持向量机(SVM)分类器对冗余的骨架分支进行剪枝处理.试验结果表明,该算法提取的骨架具有很好的连通性,尤其适用于提取对象狭长区域的骨架线.     

Vague集间新距离的分析和定义

Vague集的相似度量是Vague集在各个应用领域中的关键技术．根据相似工程学原理,指出一个相似度量必须满足的约束条件,提出一种改进的Vague集相似度量公理化定义,然后引入一种新的Vague集相似度量方法,并证明它满足这些公理化条件,最后,用实例说明其应用以及该方法的有效性和直观性．     

基于熵理论的加权马氏距离及其应用

分析了加权马氏距离判别分析中的权值问题,提出了用熵理论来确定加权马氏距离中权值的方法。实证分析显示基于熵理论的加权马氏距离要优于基于主成分的加权马氏距离。     

空间极值距离的一个不等式及其应用

本文在讨论空间极值距离的基础上,建立了一个关于极值面积的不等式,并由此建立了关于空间K—Q·C映照的一个偏差定理。所得的结果可以看做Ahlfors关于平面相应结果在空间中的推广形式。     

基于证据间距离和不确定性度量的证据组合方法

针对Dempster组合公式无法组合冲突证据的问题,提出了一种证据组合的权重分配方法.该方法充分考虑证据间的关系和证据本身的特性,用证据间距离度量证据间的不一致程度,用证据的不确定度来度量证据本身的不确定性;在此基础上扩展了文献[7]提出的权重确定准则,认为证据组合规则既要考虑使组合后证据与各源证据间的距离和尽量小,也要注重降低组合后证据本身的不确定性.最后根据新的准则给出了权重因子的确定算法和证据组合方法.算例表明,该方法改进了文献[7]权重分配方法的结果,且使权重分配更加灵活.     

基于类内和类间距离的粗粒度并行AP聚类算法

近邻传播(Affinity Propagation,AP)聚类是基于数据点间消息传递的算法,主要通过数据间的相似度实现聚类.与传统的聚类方法相比,AP聚类无需事先给定聚类数目就可实现聚类,因此具有快速高效的优点,然而在处理高维复杂数据集时存在随着聚类效率提升而准确度不高的问题.为改善AP聚类算法的效率和精度,提出基于类内和类间距离的粗粒度并行AP聚类算法——IOCAP.首先引入粒度思想将初始数据集划分成多个子集;其次对各子集结合类内和类间距离进行相似度矩阵的改进计算,最后基于MapReduce模型实现改进后的并行AP聚类.在真实数据集上的实验表明,IOCAP算法在大数据集上有较好的适应性,能在保持AP聚类效果的同时有效地提升算法精度.     

基于Kendall秩相关系数的稳健马氏距离及其应用

在聚类分析或判别分析问题中,人们通常使用距离来度量观测的相似程度。其中,马氏距离考虑了数据之间的相关性,并可以消除量纲,从而得到了广泛应用。但在异常值存在时,马氏距离估计不够稳健。因此,构造稳健的马氏距离具有重要应用价值。本文基于Kendall秩相关系数来估计稳健的马氏距离,同时通过数值模拟,将稳健的马氏距离与传统马氏距离进行比较。结果表明在异常值存在时,稳健估计的马氏距离所得结果优于传统马氏距离。     

极坐标系下的点到直线距离公式及其应用

试图解决在极坐标系下如何求点到直线的距离问题，然后举例说明点到直线的距离公式的用途     

Homology between human bladder carcinoma oncogene product and mitochondrial ATP-synthase

More than 10 different dominant transforming genes (oncogenes) have been identified in human tumours. A human bladder carcinoma oncogene, closely related in sequence to retroviral transforming genes, is split into four exons; the first encodes the N-terminal 37 residues of p21, a protein of unknown function. The oncogene is activated by a single point mutation (guanine to thymine) resulting in the change glycine to valine at position 12 of p21 (refs 3, 4). We report here that the amino acid sequence surrounding this residue is highly homologous to the beta-subunit of mitochondrial and bacterial ATP-synthase in the region of the polypeptide that is believed to contribute to nucleotide binding. Thus, p21 may form part of an enzyme that uses purine nucleotides in catalysis. This is consistent with the finding that an equivalent murine oncogene product binds GTP.     

蛋白质编码区碱基分布与终止密码子的关系

对11种具有不同G C含量的微生物基因组蛋白质编码区进行统计分析，结果显示蛋白质编码区3个密码子位碱基分布具有明显的不对称性，与终止密码子对应的一些单、双核苷酸出现的频率很低，由此得出结论：终止密码子对编码区碱基的使用起重要限制作用．     

Association between an oncogene and an anti-oncogene: the adenovirus E1A proteins bind to the retinoblastoma gene product

One of the cellular targets implicated in the process of transformation by the adenovirus E1A proteins is a 105K cellular protein. Previously, this protein had been shown to form stable protein/protein complexes with the E1A polypeptides but its identity was unknown. Here, we demonstrate that it is the product of the retinoblastoma gene. The interaction between E1A and the retinoblastoma gene product is the first demonstration of a physical link between an oncogene and an anti-oncogene.     

Domain structure of human glucocorticoid receptor and its relationship to the v-erb-A oncogene product

The interaction of steroids with their nuclear receptors induces a cascade of regulatory events that results from the activation of specific sets of genes by the hormone/receptor complex. Steroids, either acting alone or possibly synergistically with other growth factors, can influence the DNA synthesis and proliferation of specific target cells, initiate developmental pathways and activate expression of the differentiated phenotype. Moreover, steroid hormones have been implicated in abnormal growth regulation both in tumours and tumour-derived cell lines. The identification of complementary DNAs encoding the human glucocorticoid receptor (hGR) predicts two protein forms (alpha and beta; 777 and 742 amino acids long, respectively) which differ at their carboxy termini. We report here that both forms of the receptor are related, with respect to their domain structure, to the v-erb-A oncogene product of avian erythroblastosis virus (AEV), which suggests that steroid receptor genes and the c-erb-A proto-oncogene are derived from a common primordial regulatory gene. Therefore, oncogenicity by AEV may result, in part, from the inappropriate activity of a truncated steroid receptor or a related regulatory molecule encoded by v-erb-A. This suggests a mechanism by which transacting factors may facilitate transformation. We also identify a short region of hGR that is homologous with the Drosophila homoeotic proteins encoded by Antennapedia and fushi tarazu.     

The ras oncogene product p21 is not a regulatory component of adenylate cyclase

Harvey (Ha-MSV) and Kirsten (Ki-MSV) murine sarcoma viruses induce tumours in animals and transform various cells in culture because of the expression of the ras oncogene product, p21 (ref. 1). Proto-oncogenes homologous with these genes are highly conserved evolutionarily and activated ras oncogenes have been detected in many human cancers. Whether c-ras oncogenes are directly responsible for human carcinogenesis is uncertain; however, it is clear that p21 mediates virus-induced transformation, although by an unknown mechanism. Epithelial and fibroblast cell lines transformed with Ha-MSV and Ki-MSV express p21 (ref. 8) and exhibit reduced adenylate cyclase activity. Like the guanine nucleotide regulatory proteins, Ns and Ni, which mediate stimulation and inhibition, respectively, of adenylate cyclase, p21 is a membrane-associated GTP binding protein, which exhibits GTPase activity. These similarities suggest that p21 and the adenylate cyclase regulatory proteins are related in cellular function, and that p21 depresses adenylate cyclase by inhibiting the activity of Ns or acting as Ni. We have therefore now examined the structural and functional similarities between p21 and Ns and Ni and find no evidence that p21 regulates adenylate cyclase activity by acting as one of these regulatory proteins.     

正七边形与单形的位似距离

引进了与凸体间Banach—Mazur距离相关的位似距离的概念，证明了平面上正七边形与其面积最大内接单形之间的位似距离近似为2．0489。     

天体距离的测定

介绍了太阳系和其它星系内天体之间距离的测定方法．     

Structural differences between a ras oncogene protein and the normal protein

One of the most commonly found transforming ras oncogenes in human tumours has a valine codon replacing the glycine codon at position 12 of the normal c-Ha-ras gene. To understand the structural reasons behind cell transformation arising from this single amino acid substitution, we have determined the crystal structure of the GDP-bound form of the mutant protein, p21(Val-12), encoded by this oncogene. We report here the overall structure of p21(Val-12) at 2.2 A resolution and compare it with the structure of the normal c-Ha-ras protein. One of the major differences is that the loop of the transforming ras protein that binds the beta-phosphate of the guanine nucleotide is enlarged. Such a change in the 'catalytic site' conformation could explain the reduced GTPase activity of the mutant, which keeps the protein in the GTP bound 'signal on' state for a prolonged period time, ultimately causing cell transformation.