布朗运动与扩散方程

引入差分方程研究布朗运动，会发现极限情况下的布朗运动所遵循的偏微分方程就是数学物理方程中的扩散方程。如果在扩散方程推导的教学中，将本文内容介绍给学生，会使学生对自然界的统一性，对描述随机现象与描述必然现象两类数学模型之间的内在联系有进一步的认识。     

预蠕变—塑性的本构描述及其实验验证

基于热力学相容的本构模型并合理地定义广义时间标度，得到了描述蠕变，塑性及其交互作用的统一型本构方程。进而通过对蠕变、塑性及其交互作用过程中材料内部子结构及其变化的分析，将材料的强化分解为对应于累积非弹性变形的强化和由蠕变变形导致的附加强化。对对高温环境二维应力路径下３１６不锈钢的预蠕变－塑性变形过程进行了分析，取得了与Ｏｈａｓｈｉ等的实验数据相吻合的结果。     

充液航天器试验的三维数值分析

对自旋充液航天器地面气浮台试验的动力学特性进行了分析和计算。以刚体系统的动量矩定理和流体运动的基本方程为基础，考虑液体晃动、涡旋、重力、离心力及Ｃｏｒｉｏｌｉｓ力等因素的影响，并运用Ｐｆｅｉｆｆｅｒ推广的关于流体均匀涡旋运动的理论，导出了液体晃动的边值问题和流固耦合旋转系统运动的联立微分方程组。运用边界元方法求解了重力场中部分充液偏置贮箱内液体晃动的三维边值问题，并将系统运动的联立微分方程组交换后化为广义特征值问题来求解。从而求得液体晃动的能量耗散率和系统的章动时间常数。     

A binding site for the T-cell co-receptor CD8 on the alpha 3 domain of HLA-A2

Adhesion measurements between CD8 and 48 point mutants of HLA-A2.1 show that the CD8 alpha-chain binds to the alpha 3 domain of HLA-A2.1. Three clusters of alpha 3 residues contribute to the binding, with an exposed, negatively charged loop (residues 223-229) playing a dominant role. CD8 binding correlates with cytotoxic T-cell recognition and sensitivity to inhibition by anti-CD8 antibodies. Impaired alloreactive T-cell recognition of an HLA-A2.1 mutant with reduced affinity for CD8 is not restored by functional CD8 binding sites on an antigenically irrelevant class I molecule. Therefore, complexes of CD8 and the T-cell receptor bound to the same class I major histocompatibility complex molecule seem to be necessary for T-cell activation.     

Nonlinear forecasting as a way of distinguishing chaos from measurement error in time series

An approach is presented for making short-term predictions about the trajectories of chaotic dynamical systems. The method is applied to data on measles, chickenpox, and marine phytoplankton populations, to show how apparent noise associated with deterministic chaos can be distinguished from sampling error and other sources of externally induced environmental noise.     

New Sivapithecus humeri from Pakistan and the relationship of Sivapithecus and Pongo

New humeri of two species of the Miocene hominoid Sivapithecus are described from near Chinji in Pakistan from between approximately 9 and 11 Myr ago. Sivapithecus, a middle and late Miocene hominoid from Turkey and Indo-Pakistan, is overall unlike any living hominoid, although facial-palatal similarities to the extant orangoutan, Pongo, have been used to support a hypothesis of close relationship. Living hominoids have postcranial similarities assumed to be shared derived, among them features of the proximal humerus. However, the new Sivapithecus proximal humeri differ from those of living hominoids, supporting an alternative hypothesis in which Sivapithecus and Pongo are not closely related. It is not clear how to choose between these incompatible hypotheses.     

Genetic mapping of chronic childhood-onset spinal muscular atrophy to chromosome 5q11.2-13.3

SPINAL muscular atrophy (SMA) describes a group of heritable degenerative diseases that selectively affect the alpha-motor neuron. Childhood-onset SMAs rank second in frequency to cystic fibrosis among autosomal recessive disorders, and are the leading cause of heritable infant mortality. Predictions that genetic heterogeneity underlies the differences between types of SMA, together with the aggressive nature of the most-severe infantile form, make linkage analysis of SMA potentially complex. We have now analysed 13 clinically heterogeneous SMA families. We find that 'chronic' childhood-onset SMA (including intermediate SMA or SMA type II, and Kugelberg-Welander or SMA type III) is genetically homogeneous, mapping to chromosomal region 5q11.2-13.3.     

Retinal degeneration in the rd mouse is caused by a defect in the beta subunit of rod cGMP-phosphodiesterase

Mice homozygous for the rd mutation display hereditary retinal degeneration and the classic rd lines serve as a model for human retinitis pigmentosa. In affected animals the retinal rod photoreceptor cells begin degenerating at about postnatal day 8, and by four weeks no photoreceptors are left. Degeneration is preceded by accumulation of cyclic GMP in the retina and is correlated with deficient activity of the rod photoreceptor cGMP-phosphodiesterase. We have recently isolated a candidate complementary DNA for the rd gene from a mouse retinal library and completed the characterization of cDNAs encoding all subunits of bovine photoreceptor phosphodiesterase. The candidate cDNA shows strong homology with a cDNA encoding the bovine phosphodiesterase beta subunit. Here we present evidence that the candidate cDNA is the murine homologue of bovine phosphodiesterase beta cDNA. We conclude that the mouse rd locus encodes the rod photoreceptor cGMP-phosphodiesterase beta subunit.