Assessing population differentiation and isolation from single-nucleotide polymorphism data

Summary. We introduce a new, hierarchical, model for single-nucleotide polymorphism allele frequencies in a structured population, which is naturally fitted via Markov chain Monte Carlo methods. There is one parameter for each population, closely analogous to a population-specific version of Wright's F _ST , which can be interpreted as measuring how isolated the relevant population has been. Our model includes the effects of single-nucleotide polymorphism ascertainment and is motivated by population genetics considerations, explicitly in the transient setting after divergence of populations, rather than as the equilibrium of a stochastic model, as is traditionally the case. For the sizes of data set that we consider the method provides good parameter estimates and considerably outperforms estimation methods analogous to those currently used in practice. We apply the method to one new and one existing human data set, each with rather different characteristics—the first consisting of three rather close European populations; the second of four populations taken from across the globe. A novelty of our framework is that the fit of the underlying model can be assessed easily, and these results are encouraging for both data sets analysed. Our analysis suggests that Iceland is more differentiated than the other two European populations (France and Utah), a finding which is consistent with the historical record, but not obvious from comparisons of simple summary statistics.     

语言技能及其在教学中的相互作用

语言教学的目的是开发所有语言资源 ,并将这些资源传授给语言学习者 ,使他们能够正确地表达自己的思想。随着社会的进步和科技的发展 ,传统的教学手段已无法满足教学改革的需要 ,急需找到适合已有的各种交流系统的教学手段。本文首先对语言的四个基本技能进行深入的分析 ,然后探讨了采用现代技术的教学手段的可能性 ,最后就如何发展外语教学 ,提出了一些观点和建议     

News Framing and Cueing of Issue Regimes: Explaining Clinton's Public Approval in Spite of Scandal

During the period of exceedingly critical news coverage surroundingthe Monica Lewinsky debacle, President Bill Clinton's job approvalratings were at some of the highest levels they reached duringhis tenure in office. Given this public response, many pollsters,pundits, and scholars argued that news coverage of the scandalmust have been largely irrelevant to the public. Our view countersthese claims by advancing a theory that recognizes that citizens'political preferences are influenced substantially by framesand cues provided by news media. To test our ideas, we drawupon three types of data, all from January 1993 to March 1999:(a) a longitudinal content analysis of major news media, (b)a time-trend of opinion polls on presidential job approval,and (c) monthly estimates of real disposable personal income,seasonally adjusted. Analyses reveal that news media emphasisupon and framing of certain issue regimes—to the framingof the scandal in terms of the strategic motives of conservativeelites.     

Policy experiments with a paper industry model

A simulation model of the paper industry is briefly described, as is the manner in which the model was developed. The model was built in order to carry out a series of simulation experiments. The purpose of these experiments was to compare the effectiveness of a number of sets of alternative policies, which had been devised with the objective of ameliorating the effect on the industry of demand fluctuations. In addition, the experiments were intended to detect potential supply dislocations likely to be created anywhere in the system as a result of employing the policies under test. Both the experiments themselves, and the results obtained from them, are described and discussed.     

The Implication of Wife's Occupational Attainment for Husband's Class Identification*

Drawing upon research indicating that the subjective class identifications of working wives are to a considerable extent the result of their own occupational attainments, this study seeks to determine if husbands of working wives also derive perceptions of status from their wives' occupational attainments. Regression analysis is conducted on a subset of husbands of working wives in three General Social Surveys gathered from 1973 to 1975. A husband's level of subjective class identification is unaffected by the occupational achievements of his working wife. If husbands and wives derive perceptions of status from different sources, then they may not perceive themselves as sharing the same level of status in society.     

THE CONTROL OF EXTERNALITIES IN A GROWING URBAN ECONOMY

The received theory of externality control, which implicitly assumes that both the social marginal damage and marginal treatment cost schedules will remain fixed during the time any policy is operative, concludes that an effluent tax and an auction of rights to emit pollutants in the amount of a given emissions standard will be equally efficient in meeting that standard. We show that urban growth causes shifts in both schedules. These shifts in turn substantially increase the welfare loss from a fixed effluent tax relative to that from an auction market with a fixed number of licenses.     

Contextual influences on personnel policies and programs: an explanatory model

There has been a general absence of research to explain why personnel policies develop in organizations. This article has two objectives: (a) development of a theoretically relevant scheme for clustering personnel policies for analytic purposes, and (b) presentation of an explanatory model suggesting how contextual influences shape these policies.     

The distribution of random determinants

The exact distribution of |Δn| where Δn is a random determinant with independent and identically distributed exponential elements is given for the cases n = 2 and 3. From the investigation of the behaviour of the density functions for these cases it is conjectured that for any fixed n, the probability density of |Δn| for large values of the argument is the same as the density of (Y/n)ⁿ, where Y is a gamma random variable.