Prediction of sites under adaptive evolution in flavin-containing monooxygenases: Selection pattern revisited

Flavin-containing monooxygenase (FMO), like cytochrome P450 (CYP), is a monooxygenase that uses the reducing equivalents of NADPH to reduce one atom of molecular oxygen to water, while the other atom is used to oxidize the substrate. Recently, it was shown that some CYP isoforms have been subject to positive selection. However, it is unknown whether the highly conserved phase I detoxification enzyme, FMO, has undergone similar positive Darwinian selection. We used maximum-likelihood models of codon substitution, evolutionary fingerprinting, and cross species comparison to investigate the occurrence of adaptive evolution in FMO sequences. We used recent genomic data from a range of species, including vertebrates and invertebrates. We present the evidence for the occurrence of adaptive evolution in mammalian FMO 3, 4, 5, and fugu FMOs but not in mammalian FMO 1, FMO 2, frog FMOs, other fish FMOs and invertebrate FMOs. The sites under adaptive evolution were significantly associated with the insertion domain in mammalian FMO 5. We identified specific amino acid sites in FMOs 3–5 that are likely targets for selection based on the patterns of parallel amino acid change. The most likely role of adaptive evolution is the repair of mutations that permitted optimal NADP+ binding and improved catalytic efficiency. The occurrence of positive selection during the evolution of phase I detoxification enzymes such as FMOs 3–5 and fugu FMO suggests the occurrence of both high selection pressure acting on species within their unique habitats and significant changes in intensity and direction (forms of xenobiotics and drugs) resulting from changes in microhabitat and food.     

Comprehensive optimal control on seismic response of a single-tower self-anchored suspension bridge

Earthquake may cause severe damage to all kinds of bridge such as the falling down of the girder; therefore,effective measures should be employed to control the seismic displacement. In this paper,the method of comprehensive optimal control,com-bined with analytic hierarchy process,is employed to investigate the seismic response control of the Nanjing Jiangxinzhou Bridge,which is a single-tower self-anchored suspension bridge (SSSB). Also,3-dimensional nonlinear seismic response analyses are con-ducted. Three types of practical connection measures for seismic response control of SSSB are investigated,and the optimal pa-rameters of the connection devices are achieved by this method. Results show that both the elastic connection devices and the damp-ers with rational parameters can reduce the seismic displacement of the bridge effectively,but the elastic connection devices will in-crease the seismic force of the tower. When all factors are consid-ered,the optimal measure is by using the elastic connection devices and the dampers together. These results can provide references for seismic response control of SSSBs.     

弹性碰撞的图示分析法

通过引入牵连动量和相对动量等物理量,用图示分析法研究了弹性碰撞.研究结果表明,该方法可以形象而直观地描述弹性碰撞的过程和结果,对弹性碰撞的理论研究和实际应用都有重要的意义.     

《数值分析》课程教学改革探讨

介绍《数值分析》教学中存在的教学内容多与教学课时少、重理论轻实践和教学手段与考核方式单一等问题.针对这些问题,我们在《数值分析》课程教学中提出相应的教学内容、教学手段和考核方式的改进措施.     

Earliest record of megaphylls and leafy structures, and their initial diversification

Evolutionary changes in the structure of leaves have had far-reaching effects on the anatomy and physiology of vascular plants, resulting in morphological diversity and species expansion. People have long been interested in the question of the nature of the morphology of early leaves and how they were attained. At least five lineages of euphyllophytes can be recognized among the Early Devonian fossil plants (Pragian age, ca. 410 Ma ago) of South China. Their different leaf precursors or "branch-leaf complexes" are believed to foreshadow true megaphylls with different venation patterns and configurations, indicating that multiple origins of megaphylls had occurred by the Early Devonian, much earlier than has previously been recognized. In addition to megaphylls in euphyllophytes, the laminate leaf-like appendages (sporophylls or bracts) occurred independently in several distantly related Early Devonian plant lineages, probably as a response to ecological factors such as high atmospheric CO 2 concentrations. This is a typical example of convergent evolution in early plants.     

基于f可调δ-P1近似的生物组织光学特性参数的解析

呈现一种基于可调f参数的δ-P1近似理论,结合自适应遗传算法和非线性曲线拟合,获得生物组织光学特性参数(吸收系数、散射系数和各向异性因子)的多步非线性优化算法;其中关键步骤是第一步采用自适应遗传算法精确地确定自由程,而优化用到数据来源于蒙德卡洛模拟(MC).结果表明,结合可调f参数的δ-P1近似理论,采用以自适应遗传为主的算法可以大大减少生物组织光学特性参数的估计误差.     

一类非线性差分方程组的全局渐近稳定性

对一类非线性差分方程组的正解的收敛性进行了研究,当函数if和gi(i=1,2,4,5)满足一定的条件时,证明了该方程组有唯一的正平衡解且是全局渐近稳定的.     

语音识别门禁系统关键技术所究

通过对语音识别技术的原理进行分析,结合特定人语音识别技术在门禁系统中的具体应用,从语音信号的预处理、信号端点检测、特征信号的提取到识别策略的算法等关键技术上进行研究,从技术角度阐明了该系统在理论上的合理性和可行性,并通过实验说明系统在噪声干扰的情况下性能没有明显的下降.     

基于ORB的无线JMS消息系统的研究与设计

在无线互联网时代的21世纪,移动计算与应用已成为新的技术发展方向和应用热点.企业应用移动化为用户提供了高粘度的、实时的、全方位的信息服务.为基于J2ME的移动应用提供一套完整可靠的JMS消息服务,叙述了基于ORB的无线JMS消息系统的结构、功能,并给出了设计方案.