Quantitative genetic models of sexual selection

Summary Quantitative genetic models of sexual selection have disporven 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. Quantittive 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^36–38,58. Thus the feature of indeterminate equilibria (outcome dependent on initial conditions) is common to both types of model.     

南水北调东线工程调水期洪泽湖水质变化规律分析

为了解南水北调东线工程调水期间洪泽湖水质变化,基于2013—2020年洪泽湖调水期水质监测数据,采用Daniel趋势检验分析水质年变化趋势,通过空间插值得出各湖区水质分布规律,并进一步用主成分分析法分析水质主要污染类型。结果表明：2013—2020年洪泽湖调水期水质在合格至轻度污染之间,TP和TN为主要超标因子;时间上水质有变好趋势,空间上过水区水质最差,但有转好趋势,而成子湖区和溧河洼区有所恶化;污染类型以富营养化污染为主,氮磷营养盐影响较大;水质污染以入湖河流输入和建设用地增加人类活动的污染为主要来源,还伴有偶发污染事故;时间上洪泽湖对东线输水的综合水质有改善趋势,建议进一步加强相关污染防治工作,保护洪泽湖水环境,保障南水北调东线工程输水水质安全。     

Error rates in quadratic discrimination with constraints on the covariance matrices

In multivariate discrimination of several normal populations, the optimal classification procedure is based on quadratic discriminant functions. We compare expected error rates of the quadratic classification procedure if the covariance matrices are estimated under the following four models: (i) arbitrary covariance matrices, (ii) common principal components, (iii) proportional covariance matrices, and (iv) identical covariance matrices. Using Monte Carlo simulation to estimate expected error rates, we study the performance of the four discrimination procedures for five different parameter setups corresponding to standard situations that have been used in the literature. The procedures are examined for sample sizes ranging from 10 to 60, and for two to four groups. Our results quantify the extent to which a parsimonious method reduces error rates, and demonstrate that choosing a simple method of discrimination is often beneficial even if the underlying model assumptions are wrong.The authors wish to thank the editor and three referees for their helpful comments on the first draft of this article. M. J. Schmid supported by grants no. 2.724-0.85 and 2.038-0.86 of the Swiss National Science Foundation.     

湖北省经济可持续发展动态分析

搜集了湖北省1998～2002年国民经济发展的有关数据，按照可持续发展的要求，建立了经济可持续发展的多层次指标体系；借助基于主成分分析的建模方法，就实现湖北省经济、资源、环境之间协调发展的问题进行了研究，建立了湖北省经济、资源、环境可持续发展的数学模型，并利用统计软件SPSS和EXCEL对模型进行了求解，对模型的结果进行了分析和讨论．     

基于主成分分析的建筑空调系统传感器故障检测

在已经建立的建筑空调系统仿真器的基础上,针对系统的温度、湿度、流量传感器提出了一种基于主成分分析的传感器故障诊断方法.该方法根据系统正常的历史运行数据建立数理统计模型,通过传感器实际测量数据与正常数据阵在故障子空间投影的比较,对传感器的故障进行检测.仿真试验表明,该方法能够诊断出固定偏差和漂移故障,为进一步研究传感器的故障诊断提供了必要的基础.     

工程机械零件的可靠性优化设计

通过对机械产品可靠性的评价,分析了传统设计方法与可靠性设计方法在设计思想、设计原理上的区别.运用可靠性理论与最优化设计技术,提出了机械零部件的可靠性优化设计方法.在满足可靠度约束及结构几何约束的条件下,以体积最小作为优化目标函数进行可靠性优化设计,得到了比常规设计更为合理的设计结果.     

双向微积-连续分部积分研究

应用微积恒等变形规律，提出双向微积一连续分部积分公式，可以快速的解决一类高次多项式与指数函数、三角函数乘积的积分问题．     

杜诗中"自"字与诗中的"二元主体"世界

杜甫在诗中喜用“自”字。在其诗中，“自”字可以当代词，也可以当介词。当它作为代词，指代物的时候，诗中的“物”成为和人一样的独立的主体，拥有了独立的情感和意志，诗中世界成为了“二元主体”的世界。诗中空灵澄明的意境得以深化，诗歌的艺术空间得以拓展。这种物的独立和海德格尔诗学中所推崇的人与物的“敞开”，有殊途同归之妙。略有不同的是，杜甫对国家和百姓的不能忘怀，使得他的个人意志虽然在某些时候弱化，但始终没有丧失，这使他和海德格尔诗学中那完全“自在生存的人”是不同的。但这也正是他的伟大之处。     

加权主成分分析法在公路网综合评价中的应用

城市公路网的分析与评价对于公路网规划项目开发、实施决策具有重要的理论价值和现实意义．建立了基于加权主成分分析法的公路网综合评价模型，并给出了评价案例评价结果表明，利用加权主成分分析法评价公路网可以将主成分分析法的客观分析和层次分析法的主观分析有机地结合起来，其评价结果更加全面、更加符合客观实际情况。