非线性再生散度随机效应模型的极大似然估计及EM算法

非线性再生散度随机效应模型是指数族非线性随机效应模型和非线性再生散度模型的推广和发展．通过视模型中的随机效应为假想的缺失数据和应用Metropolis-Hastings（MH）算法,提出了模型参数极大似然估计的Monte-Carlo EM（MCEM）算法,并用模拟研究和实例分析说明了该算法的可行性．     

嗅觉系统神经网络模型的模拟与动力学特性分析

在哺乳动物嗅觉系统的拓扑结构及生理实验的基础上建立了一套非线性动力学神经网络模型．此模型在模拟嗅觉神经系统方面有着突出的优点,同时在信号处理以及模式识别中表现出了奇异的混沌特性．着重描述了K系列模型的非线性动力学特性,并通过数值模拟进行分析．     

非线性再生散度随机效应模型的极大似然估计及随机逼近算法

非线性再生散度随机效应模型包括了非线性随机效应模型和指数族非线性随机效应模型等．通过视模型中的随机效应为假想的缺失数据和应用Metropolis-Hastings(简称MH) 算法,提出了模型参数极大似然估计的随机逼近算法．模拟研究和实例分析表明了该算法的可行性．     

带一个参数的四阶边值问题的一个变号解

讨论了带一个参数的非线性四阶狄利克雷边值问题变号解的存在性．在非线性项满足一定条件时,通过利用一些新的概念如O-有界锥和O-正算子,我们得到该边值问题至少存在一个变号解．     

非线性自食种群动力系统的稳定性

本文讨论了一类主要由昆虫自食引起的非线性种群动态模型的稳定性．首先给出确定性模型,并着重讨论其一个特殊情形．通过在参数空间中辨识稳定域的边界,可以相对直观地分析种群动态．对于随机模型,是利用在确定性模型中加入对数尺度下的正态随机项形成的,该模型具有较好的统计性质,便于将现实的非线性时间序列数据引进系统中来．     

描述神经元相互作用的非线性动力学方程的解析解

神经系统是由大量神经元构成的非线性动力系统,动力学行为十分复杂ＦＨＮ模型提供了在该系统中观察时间周期振荡这种非线性现象的实验证据．本文利用扰动法从理论上求出了ＦＨＮ模型所给出的非线性动力学方程的解析解,为进一步深入研究神经系统的动力学行为提供了理论依据     

一类具有非线性控制和基层具有饱和吸收率的恒化器藻类模型

本文通过对藻类的增长率和基层的吸收率提出有生物意义的表达式,研究了一类具有非线性控制藻类恒花器模型．用定性理论证明了非线性控制可以使变产量的恒化器模型有一个全局渐进稳定的正平衡点．     

非线性森林发展系统研究进展

就近年来国内外对非线性森林发展系统的研究进展做一综述，介绍了一些非线性森林发展系统模型，分析了非线性森林系统的研究结果。     

一具有非线性发生率传染病模型的稳定性和霍普夫分支

在这篇文章中,我们研究了一具有非线性发生率的传染病模型．该模型经历了鞍结点分支和霍普夫分支．我们对模型的霍普夫分支进行了详细的分析,得知该霍普夫分支是超临界的．此外,我们给出了支持理论分析的数值模拟．     

非线性年龄结构种群发展方程解的存在唯一性

本文讨论非线性年龄结构种群动力系统,证明了方程的解的存在唯一性．     

Covarion structure in plastid genome evolution: a new statistical test

Covarion models of molecular evolution allow the rate of evolution of a site to vary through time. There are few simple and effective tests for covarion evolution, and consequently, little is known about the presence of covarion processes in molecular evolution. We describe two new tests for covarion evolution and demonstrate with simulations that they perform well under a wide range of conditions. A survey of covarion evolution in sequenced plastid genomes found evidence of covarion drift in at least 26 out of 57 genes. Covarion evolution is most evident in first and second codon positions of the plastid genes, and there is no evidence of covarion evolution in third codon positions. Therefore, the significant covarion tests are likely due to changes in the selective constraints of amino acids. The frequency of covarion evolution within the plastid genome suggests that covarion processes of evolution were important in generating the observed patterns of sequence variation among plastid genomes.     

发育重演律与生物进化

发育重演律是生物个体发育的一般规律,该规律认为生物个体的发育是类囊胚不断形成和演化的过程,并认为生物进化亦是类囊胚不断形成和演化的过程.因类囊胚层级不断增加而导致的生物体结构复杂程度提高的演化为纵向进化,而不能提高生物体复杂程度的演化为横向演化,生物的纵向进化具有周期性.生物种系进化与个体发育之间具有严格的对应关系,一个物种经历的纵向进化的周期数与该物种所属个体完成发育所经历的细胞分化的周期数相等.     

Relationships among Teachers’ Knowledge and Beliefs Regarding the Teaching of Evolution: A Case for Turkey

The research study investigated the possible associations among science and biology teachers?? knowledge and belief variables concerning teaching evolution in science and biology classes. Specifically, this study examined how a set of variables including teachers?? understanding of evolution and nature of science (NOS) is related to the set of variables including teachers?? acceptance of evolution and perceptions of teaching evolution (i.e., perceptions of the necessity of addressing evolution in their classrooms, perceptions of the factors that impede addressing evolution in their classrooms, and personal science teaching efficacy beliefs regarding evolution). Data were collected from science and biology teachers through administration of Evolution Content Knowledge Test, Measure of Acceptance of the Theory of Evolution, Nature of Science as Argument Questionnaire and Teachers?? Perceptions of Teaching Evolution Scale. Canonical correlation analysis findings suggested that teachers who had thorough understanding of evolution and NOS were likely to both accept the scientific validity of evolution and believe the necessity of addressing evolution in the classrooms. On the other hand, teachers with thorough understanding of evolution and NOS did not necessarily believe that they have a stronger sense of self-efficacy beliefs regarding teaching evolution and that there are fewer obstacles to addressing evolution in the classroom. The research is significant in that it provides empirical evidence clarifying the interactions between teachers?? understanding and beliefs in teaching evolution. Implications for science teacher education are discussed.     

Perspective: reverse evolution

For some time, the reversibility of evolution was primarily discussed in terms of comparative patterns. Only recently has this problem been studied using experimental evolution over shorter evolutionary time frames. This has raised questions of definition, experimental procedure, and the hypotheses being tested. Experimental evolution has provided evidence for multiple population genetic mechanisms in reverse evolution, including pleiotropy and mutation accumulation. It has also pointed to genetic factors that might prevent reverse evolution, such as a lack of genetic variability, epistasis, and differential genotype-by-environment interactions. The main focus of this perspective is on laboratory studies and their relevance to the genetics of reverse evolution. We discuss reverse evolution experiments with Drosophila, bacterial, and viral populations. Field studies of the reverse evolution of melanism in the peppered moth are also reviewed.     

体内连续进化技术的研究进展

实验室进化是遗传育种、提高微生物性能的重要方式。近几十年来,实验室进化的方法快速发展,应用也越来越广泛,但是常见的菌株进化策略以及针对特定蛋白的进化存在突变过程不连续,需要多轮操作、工作量大等缺点。微生物突变和筛选技术的进步促进了体内连续进化的发展,大大提高了实验室进化的效率。体内连续进化技术实现了体内突变,完美地把突变与筛选相结合,以最少的人工干预进化出特定表型。文中总结了近年来在微生物底盘中开发的基因组范围的体内连续进化技术,以及独立于基因组的针对特定蛋白的体内连续进化技术,主要对这些技术实现体内连续突变的原理及其相关应用进行了介绍。在此基础上,分析了现有技术的优缺点,并对体内连续进化技术的发展进行了展望。     

Thoughts on the cultural evolution of man. Developmental imprinting and transgenerational effect

The biological evolution of man stopped since it has been conveyed to the objects, created by man. This paper introduces the concept of "conveyed evolution". Being part of the cultural evolution, the conveyed evolution is a continuation of the biological one. There are several similarities between the laws of biological and conveyed evolution, albeit the differences are important as well. Some laws of the conveyed evolution are described here. The conveyed evolution has man-made repair mechanisms (medicine, protection of environment) which defend man from harm. Man's fragility limits the progress of conveyed evolution. However, artificial compounds or environmental pollutants which are provoked by the conveyed evolution induce chemical (hormonal) imprinting in the developmental critical periods, which is transmitted to the progeny generations (transgenerational effect). This could cause evolutionary alterations without mutation.     

A field guide for teaching evolution in the social sciences

The theory of evolution by natural selection has begun to revolutionize our understanding of perception, cognition, language, social behavior, and cultural practices. Despite the centrality of evolutionary theory to the social sciences, many students, teachers, and even scientists struggle to understand how natural selection works. Our goal is to provide a field guide for social scientists on teaching evolution, based on research in cognitive psychology, developmental psychology, and education. We synthesize what is known about the psychological obstacles to understanding evolution, methods for assessing evolution understanding, and pedagogical strategies for improving evolution understanding. We review what is known about teaching evolution about nonhuman species and then explore implications of these findings for the teaching of evolution about humans. By leveraging our knowledge of how to teach evolution in general, we hope to motivate and equip social scientists to begin teaching evolution in the context of their own field.     

The evolution of plant development

There has been much recent interest in the evolution of plant development and especially in trying to understand the developmental genetic basis of morphological evolution. Significant progress has been made in understanding the evolution of floral organization and the mechanisms that might underlie the evolution of compound leaves and inflorescence morphology. These advances are reinforcing the idea that phenotypic evolution can proceed via changes at few loci of large effect and that promoter evolution may be an important and frequent mechanism.     

Muslims and evolution: a study of Pakistani physicians in the United States

This study investigated the views of Pakistani-American medical doctors regarding biological evolution. We used a mixed-methods approach, chiefly consisting of a short interview that presented evolution in the contexts of microbial, animal, and human evolution; evolution's acceptability or unacceptability to Muslims; and evolution's relevance to medicine. The participants were 23 doctors attending a convention in the United States. Fourteen participants accepted evolution, three rejected evolution, and six held other views. While a majority of participants indicated that they accepted evolution, a slightly smaller plurality accepted human evolution. A majority of participants, including some who did not wholly accept or reject evolution, thought that one could mutually accept evolution and also believe in Allah. Nearly every participant, including two who rejected evolution, thought that evolution was relevant to medicine. We find that participants assigned a plurality of meanings to the theory that depended on interactions between a participant’s perception of religion, science, medicine, and a host of other cultural influences. This study is the first of a collection of studies carried out by the authors, who collected data with the same instrument in five other countries with significant populations of Muslim doctors and medical students.