The adaptive significance of sexuality

A theory of sexuality and polymorphism is proposed in which diversity at the molecular level is the adaptive response of multicellular organisms to the challenge of microparasites that have smaller genomes, shorter generation times and which can evolve more quickly than their hosts. The theory has implications for genetically homogenized crops and other cultivated plants as well as for immunology. A different function of sexuality is proposed for microorganisms that reproduce both asexually and sexually. Several possible experimental tests are discussed. Mathematical modelling techniques are outlined qualitatively and compared with game-theoretical methods which may be interpreted as simplifications of population dynamics of polymorphic host-parasite populations are referenced.     

Quantitative genetic models of sexual selection

Quantitative genetic models of sexual selection have disproven some of the central tenets of both the handicap mechanism and the 'sexy son' hypothesis. These results suggest that the 'good genes' approach to sexual selection may generally lead to erroneous results. Runaway sexual selection seems possible under a wide variety of circumstances. Quantitative genetic models have revealed runaway processes for sexually selected attributes expressed in both sexes and for attributes of parental care. Furthermore, the runaway could occur simultaneously in a series of populations that straddle an environmental gradient. While the models support the feasibility of runaway processes, empirical studies are needed to evaluate whether runaways actually happen. Estimates of critical genetic parameters are particularly needed, as well as measures of natural and sexual selection acting on the same population. The models also show that sexual selection has tremendous potential to produce population differentiation, particularly in epigamic traits. Differentiation is promoted by indeterminancy of evolutionary outcome, transient differences among populations during the final slow approach to equilibrium, sampling drift among equilibrium populations, and the tendency of sexual selection to amplify geographic variation arising from spatial differences in natural selection. Recent work with two- and three-locus models of sexual selection has produced results that parallel the results of the polygenic models. Thus the feature of indeterminate equilibria (outcome dependent on initial conditions) is common to both types of model.     

Theories that narrate the world: Ronald A. Fisher's mass selection and Sewall Wright's shifting balance

Theories are composed of multiple interacting components. I argue that some theories have narratives as essential components, and that narratives function as integrative devices of the mathematical components of theories. Narratives represent complex processes unfolding in time as a sequence of stages, and hold the mathematical elements together as pieces in the investigation of a given process. I present two case studies from population genetics: R. A. Fisher's “mas selection” theory, and Sewall Wright's shifting balance theory. I apply my analysis to an early episode of the “R. A. Fisher – Sewall Wright controversy.”     

基于结构元方法的矿井机械模糊可靠性分析

应用模糊结构元理论,对矿井可修复机械设备可靠性中的有效度进行研究.首先,定义了模糊可靠度、模糊维修度和模糊有效度,并应用结构元理论对其进行表示.提出了相关的运算定理,在此基础上,再运用结构元理论对模糊有效度进行表示.之后,提出了正序,该序为全序.最后,用算例计算模糊有效度,通过正序对有效度进行比较.结果表明,运用模糊有...     

Projection of population structure in China using least squares support vector machine in conjunction with a Leslie matrix model

China is a populous country that is facing serious aging problems due to the single‐child birth policy. Debate is ongoing whether the liberalization of the single‐child policy to a two‐child policy can mitigate China's aging problems without unacceptably increasing the population. The purpose of this paper is to apply machine learning theory to the demographic field and project China's population structure under different fertility policies. The population data employed derive from the fifth and sixth national census records obtained in 2000 and 2010 in addition to the annals published by the China National Bureau of Statistics. Firstly, the sex ratio at birth is estimated according to the total fertility rate based on least squares regression of time series data. Secondly, the age‐specific fertility rates and age‐specific male/female mortality rates are projected by a least squares support vector machine (LS‐SVM) model, which then serve as the input to a Leslie matrix model. Finally, the male/female age‐specific population data projected by the Leslie matrix in a given year serve as the input parameters of the Leslie matrix for the following year, and the process is iterated in this manner until reaching the target year. The experimental results reveal that the proposed LS‐SVM‐Leslie model improves the projection accuracy relative to the conventional Leslie matrix model in terms of the percentage error and mean algebraic percentage error. The results indicate that the total fertility ratio should be controlled to around 2.0 to balance concerns associated with a large population with concerns associated with an aging population. Therefore, the two‐child birth policy should be fully instituted in China. However, the fertility desire of women tends to be low due to the high cost of living and the pressure associated with employment, particularly in the metropolitan areas. Thus additional policies should be implemented to encourage fertility.     

牵引供电SCADA系统故障树分析研究

应用灰门故障树分析方法对牵引供电SCADA系统的可靠性进行了研究。简要介绍了灰门故障树分析方法的基本理论和牵引供电SCADA系统的基本结构;建立了牵引供电SCADA系统的故障树;用概率灰数描述部件的故障概率,用灰门代替传统逻辑门来描述部件间的联系,用故障测度描述部件的故障程度。对所建立的故障树进行了定量的计算。结果表明,应用灰门故障树分析方法的计算结果是可行有效的。     

Innovators and imitators in innovation diffusion modelling

We examine the theoretical underpinnings of the Bass innovation diffusion model and show that, contrary to the present understanding in the literature, it does not describe the behavioural theory of an innovator-imitator dichotomy within the adopting population as was intended. Rather, this model describes the behaviour of a homogeneous population in which it is assumed that product adoption occurs as a result of exposure to a news source or from the binary interaction between adopters and non-adopters. We provide an alternative framework in which the innovator-imitator explanation of diffusion is explicitly incorporated. In the so-called two-compartment model the innovators and imitators constitute two distinct but interacting subpopulations. However, the added structural complexity cannot be supported by the available diffusion data, resulting in unsatisfactory model estimation results. This suggests that the innovator-imitator population dichotomy assumed to underlie the present understanding of the innovation diffusion process may be inappropriate. Replacing it with the assumption of a homogeneous population could have potentially important implications for new product advertising strategies.     

大气折射的研究进展

介绍了近几年大气折射映射函数研究的进展、以及几个常用的映射函数。对如今广泛地应用在空间测量技术中的几种映射函数做出评述。讨论了目前在无线电波段中广泛使用的NMF模型的优点和不足之处,提出了改进方向。列出了近几年上海天文台发展的大气折射母函数方法,以及由此导出的大气折射解析解;并分析了大气折射母函数方法引出的大气延迟新连分式映射函数,以及天文大气折射的映射函数方法的优点;指出了光学波段测距精度改进的途径。结合探空气球资料,讨论了大气模式对大气折射计算的影响。     

Population genetic structure and mating system evolution in freshwater pulmonates

Freshwater gastropods (Basommatophora and Prosobranchia) harbor a variety of mating systems. In particular, apomictic parthenogenesis in prosobranchs and self-fertilization in the hermaphrodite pulmonates may be viable alternatives to outcrossing sexuality in a number of species. The coexistence of different mating systems in extant populations provides opportunities to examine the forces directing their evolution. We review the models analyzing and predicting genetic variability in subdivided populations, with an emphasis on the effects of inbreeding. Population genetic data on freshwater pulmonates are examined in the context of selfing rates and the loss of variability under selfing. Furthermore, the genetic and demographic factors thought to influence mating system evolution are considered, and we highlight the different approaches available to estimate mating system parameters, in particular the selfing rate. Recent population biological studies on polyploid species (Bulinus truncatus, Ancylus fluviatilis) indicate that selfing is the predominant mating system. These studies have contributed to a deeper understanding of conceptual issues in the evolution of selfing rates. Throughout, we emphasize the need for further carefully designed studies.     

Subjectivity and emotion in scientific research

A persistent puzzle for philosophers of science is the well-documented appeal made by scientists to their aesthetic emotions in the course of scientific research. Emotions are usually viewed as irremediably subjective, and thus of no epistemological interest. Yet, by denying an epistemic role for scientists’ emotional dispositions, philosophers find themselves in the awkward position of ignoring phenomena which scientists themselves often insist are of importance. This paper suggests a possible solution to this puzzle by challenging the wholesale identification of emotion with subjectivity. The proposed method is a naturalistic and externalist one, calling for empirical investigation into the intersubjective processes by which scientists’ emotional dispositions become refined and attuned to specific objects of attention. The proposal is developed through a critical discussion of Michael Polanyi’s theory of scientific passions, as well as plant geneticist Barbara McClintock’s celebrated “feeling for the organism.”     

MIMO-OFDM系统中基于变分Bayes EM算法的联合符号检测与鲁棒Kalman信道跟踪

基于变分Bayes期望最大化VBEM(variational Bsayes expectation maximization)算法和Turbo原理,提出了快时变信道条件下MIMO-OFDM系统中的联合符号检测与信道估计算法.在VBEM框架下,信号检测和信道估计分别由修正的列表球形译码算法和软输入Kalman算法完成,检测器和估计器分别考虑了信道和检测信号的估计误差协方差矩阵.当信道时变剧烈时,存在较大检测误差的数据在软输入Kalman算法中引入异常值(outliers),由于Kalman算法对于异常值的敏感性,系统会在错误传播的影响下出现误码平台.为削弱异常值的影响,利用鲁棒统计理论设计了VBEM框架下改进的鲁棒软输入Kalman算法,该算法能在出现异常值的条件下保持较好的信道跟踪能力.仿真结果表明:在快速时变多径信道条件下,文中设计的鲁棒VBEM算法优于传统的VBEM算法和EM算法.     

Identifying the conformational state of bi-liganded haemoglobin

While most researchers agree on the global features of cooperative ligand binding to haemoglobin (Hb), the internal mechanisms remain open to debate. This is not due to inaccurate measurements, but is rather a consequence of the cooperative ligand binding that decreases the equilibrium populations of the partially liganded states and makes observation of the transitions between these substates more difficult. For example, the equilibrium population of the doubly liganded tetramers is typically less than 5% of the total Hb. As a result many models with widely varying mechanisms may fit the oxygen equilibrium curve, but may not be consistent with observations of other parameters, such as ligand-binding kinetics or subunit association equilibria. The wide range of methods and models has led to divergent conclusions about the properties of specific substates. One notable debate concerns the properties of the doubly liganded forms. The simple two-state model predicts a shift in the allosteric equilibrium based on the number of ligands bound, but not on their distribution within the tetramer. From studies of dimer-tetramer equilibria of various pure and hybrid forms, it was concluded that a tetramer with two ligands bound on the same α β dimer (species 21, an asymmetric hybrid) shows an enhanced tetramer stability, similar to singly liganded Hb, relative to the other three types of doubly liganded tetramers which resemble the triply liganded forms [Ackers et al. (1992), Science 255: 54–63]. The implications of this model and the relevant experiments will be reviewed here. Received 27 April 1998; received after revision 17 July 1998; accepted 10 August 1998     

Novelty,coherence, and Mendeleev’s periodic table

Predictivism is the view that successful predictions of “novel” evidence carry more confirmational weight than accommodations of already known evidence. Novelty, in this context, has traditionally been conceived of as temporal novelty. However temporal predictivism has been criticized for lacking a rationale: why should the time order of theory and evidence matter? Instead, it has been proposed, novelty should be construed in terms of use-novelty, according to which evidence is novel if it was not used in the construction of a theory. Only if evidence is use-novel can it fully support the theory entailing it. As I point out in this paper, the writings of the most influential proponent of use-novelty contain a weaker and a stronger version of use-novelty. However both versions, I argue, are problematic. With regard to the appraisal of Mendeleev’ periodic table, the most contentious historical case in the predictivism debate, I argue that temporal predictivism is indeed supported, although in ways not previously appreciated. On the basis of this case, I argue for a form of so-called symptomatic predictivism according to which temporally novel predictions carry more confirmational weight only insofar as they reveal the theory’s presumed coherence of facts as real.     

Seeking representations of phenomena: Phenomenological models

A distinction is made between theory-driven and phenomenological models. It is argued that phenomenological models are significant means by which theory is applied to phenomena. They act both as sources of knowledge of their target systems and are explanatory of the behaviors of the latter. A version of the shell-model of nuclear structure is analyzed and it is explained why such a model cannot be understood as being subsumed under the theory structure of Quantum Mechanics. Thus its representational capacity does not stem from its close link to theory. It is shown that the shell model yields knowledge about the target and is explanatory of certain behaviors of nuclei. Aspects of the process by which the shell model acquires its representational capacity are analyzed. It is argued that these point to the conclusion that the representational status of the model is a function of its capacity to function as a source of knowledge and its capacity to postulate and explain underlying mechanisms that give rise to the observed behavior of its target.     

基于平均增益模型的连续型(1+1)进化算法计算时间复杂性分析

连续型进化算法的计算时间复杂性分析是进化计算理论研究的一项公开难题,目前相关研究成果较少.针对连续型(1+1)EA,基于适应值差函数提出了平均增益模型及其分析方法,给出了平均计算时间的计算理论,为算法的计算时间复杂性分析提供了依据.在此基础上,研究还选取了学术界关注的球形函数作为研究对象,分别推导了变异步长满足标准正态分布和均匀分布的连续型(1+1)EA在优化球形函数时的平均增益,并估算出了它们的平均计算时间.理论分析说明:1)两种算法的计算时间复杂性都是指数级的;2)在给定相同精度和初始适应值差的前提下,采用均匀分布变异算子的算法其寻优速度优于采用标准正态分布变异算子的算法.进一步地,通过数值实验对理论分析结果进行了验证,结果表明平均增益模型分析是有效的.     

Ambivalent effect of protein binding on computed distributions of metal ions complexed by ligands in blood plasma.

Although the absolute concentrations of metal complexes in blood plasma are controlled by protein binding, the percentage distribution of transition metal ions amongst low molecular weight ligands is not. Thus, computer simulations which omit protein equilibria can nevertheless afford reliable information about such metals in the biofluid.     

One hundred years of Weyl’s (unfinished) unified field theory

In 1918, H. Weyl proposed a unified theory of gravity and electromagnetism based on a generalization of Riemannian geometry. In spite of its elegance and beauty, a serious objection was raised by Einstein, who argued that Weyl’s theory was not suitable as a physical theory . According to Einstein, the theory led to the prediction of a “second clock effect”, which has not been observed by experiments as yet. We briefly revisit this point and argue that a preliminary discussion on the very notion of proper time is needed in order to consider Einstein’s critical point of view. We also point out that Weyl theory is basically incomplete in its original version and its completion may lead to a rich and interesting new approach to gravity.     

煤矿瓦斯事故致因分析及模型构建

统计我国2008年煤矿安全事故原因,说明煤矿瓦斯事故是造成人员伤亡和财产损失的重大原因。分析煤矿瓦斯事故的发生机理,给出其特点及演化规律,从概率的角度阐述瓦斯事故高发的原因。据此构建煤矿瓦斯事故致因理论模型,并提出防范煤矿瓦斯事故再次发生的有效对策和措施,为煤矿安全管理和决策提供重要依据。     

Holism, physical theories and quantum mechanics

Motivated by the question what it is that makes quantum mechanics a holistic theory (if so), I try to define for general physical theories what we mean by `holism'. For this purpose I propose an epistemological criterion to decide whether or not a physical theory is holistic, namely: a physical theory is holistic if and only if it is impossible in principle to infer the global properties, as assigned in the theory, by local resources available to an agent. I propose that these resources include at least all local operations and classical communication. This approach is contrasted with the well-known approaches to holism in terms of supervenience. The criterion for holism proposed here involves a shift in emphasis from ontology to epistemology. I apply this epistemological criterion to classical physics and Bohmian mechanics as represented on a phase and configuration space respectively, and for quantum mechanics (in the orthodox interpretation) using the formalism of general quantum operations as completely positive trace non-increasing maps. Furthermore, I provide an interesting example from which one can conclude that quantum mechanics is holistic in the above mentioned sense, although, perhaps surprisingly, no entanglement is needed.