How psychological stress in the workplace influences presenteeism propensity: A test of the Demand–Control–Support model

The aim of this study is to examine the influence of the sources of psychological stress at work assumed by the Demand–Control–Support (DCS) model on presenteeism propensity. Research propositions are derived from the dynamic version of the Demand–Control model, to which we added the dimension of social support, which is part of the DCS model. Data were obtained from a large representative sample consisting of 1609 public and private sector workers living in the Canadian province of Québec, who responded to a questionnaire, administered using computer-assisted interviewing over a 3-month period in 2007–2008. The results indicate that the combination of low decision authority and high supervisor's support attenuates the positive relationship between job demands and presenteeism propensity within a 10-year time frame of exposure to a new job.     

Sysmex血细胞分析仪检测中血小板参数不显示的原因分析

Sysmex血细胞分析仪是医院临床检验常规仪器。用于白细胞,红细胞,血小板及其相应参数的检测。由于其在检测过程中存在血小板参数不显示的现象,本文通过分析其不显示的原因,提示临床检验工作者努力减少血小板参数不显示的现象,从而提高血小板参数的检出率及准确率。     

Effect of Bilateral and Unilateral Plantarflexor Muscle Fatigue on Blind Navigation Precision and Gait Parameters

Abstract

The objective was to evaluate the impact of bilateral and unilateral fatigue of the plantarflexor muscles on blind navigation. Thirty-eight young adults walked 8-m without vision before fatigue (pre-fatigue), then fatigued either one or both of their plantarflexor muscles by performing isometric contractions. After each fatigue, two blind navigation trials were performed (post-fatigue trials 1 and 2). Results revealed no effect of bilateral muscle fatigue on navigation precision and gait parameters. Unilateral muscle fatigue led to longer linear distance travelled during post-fatigue trial 2 compared to pre-fatigue and to a change in angular deviation between pre- and post-fatigue. In general, results suggest that participants were able to make adaptive changes to counter muscle fatigue during blind navigation.     

基于Flanker、Stroop和Simon多重冲突驱动的认知控制机制

认知控制是维持和调整多任务目标导向的加工策略,而基于多任务冲突的认知控制是一般领域上还是特定领域上,即一种冲突是否会影响另一种冲突的解决,已有研究并没有得到统一的结论。本研究运用事件相关电位（ERP）方法考察了同一任务中不同类型冲突（Stroop、Simon和Flanker冲突）驱动认知控制调节的脑机制。数据显示：各冲突都出现了一致性效应和冲突适应性效应;实验中每种冲突的上一个trial只与该类冲突的当前trial的交互效应显著,而与其他类型冲突的当前trial的交互效应不显著;几乎所有冲突都发现了P300、N450、SP成分一致性效应。结果表明：在不同类型冲突驱动条件下,人脑能够同时监控并解决不同类型的冲突;冲突驱动的认知控制系统以局部的控制方式工作;人脑是基于多冲突驱动的认知控制系统的灵活性和某类型冲突所特有的控制机制来解决冲突,且冲突解决机制是相互独立、互不干扰的。     

Latent variable modeling in heterogeneous populations

Common applications of latent variable analysis fail to recognize that data may be obtained from several populations with different sets of parameter values. This article describes the problem and gives an overview of methodology that can address heterogeneity. Artificial examples of mixtures are given, where if the mixture is not recognized, strongly distorted results occur. MIMIC structural modeling is shown to be a useful method for detecting and describing heterogeneity that cannot be handled in regular multiple-group analysis. Other useful methods instead take a random effects approach, describing heterogeneity in terms of random parameter variation across groups. These random effects models connect with emerging methodology for multilevel structural equation modeling of hierarchical data. Examples are drawn from educational achievement testing, psychopathology, and sociology of education. Estimation is carried out by the LISCOMP program.Presidential address delivered at the Psychometric Society meetings in Los Angeles, USA and Leuven, Belgium, July 1989. The research was supported by Grant No. SES-8821668 from the National Science Foundation and by Grant No. OERI-G-86-003 from the Office for Educational Research and Improvement, Department of Education. I thank Leigh Burstein, Mike Hollis, Linda Muthén, and Albert Satorra for helpful discussions and Tammy Tam, Jin-Wen Yang, Suk-Woo Kim, and Lynn Short for computational assistance. Designs were created by Arlette Collier, Rita Ling and Jennifer Edic-Bryant.     

RESEARCH ON THE DIFFERENCE BETWEEN GENERALIZATION AND MAINTENANCE IN EXTRA-THERAPY RESPONDING1

Many authors have reported that the development of programs for producing durable extra-therapy responding lags behind the development of programs for producing initial behavior change. In Experiment I, responding was recorded continuously in both the therapy and extra-therapy settings. The results showed that one child did not generalize to the extra-therapy setting, but that other children did. However, for the children who generalized, extra-therapy responding was not maintained. Therefore, in Experiment II two variables affecting the durability of extra-therapy responding were assessed and found to be influential: (a) the use of partial reinforcement schedules in the original treatment environment; and (b) the presence of noncontingent reinforcers in the extra-therapy environment. The results suggest that there are two distinct parameters of extra-therapy responding: generalization and maintenance. A technology for producing durable extra-therapy responding is discussed in terms of different treatment procedures required for different deficits in extra-therapy responding.     

Marginal maximum likelihood estimation of item parameters: Application of an EM algorithm

Maximum likelihood estimation of item parameters in the marginal distribution, integrating over the distribution of ability, becomes practical when computing procedures based on an EM algorithm are used. By characterizing the ability distribution empirically, arbitrary assumptions about its form are avoided. The Em procedure is shown to apply to general item-response models lacking simple sufficient statistics for ability. This includes models with more than one latent dimension.Supported in part by NSF grant BNS 7912417 to the University of Chicago and by SSRC (UK) grant HR6132 to the University of Lancaster.We are indebted to Mark Reiser and Robert Gibbons for computer programming. David Thissen clarified a number of points in an earlier draft.     

东莨菪碱所致记忆障碍的脑内突触机制

研究问题是东莨菪碱所致记忆障碍的脑内突触机制,在东莨菪碱所致记忆障碍模型上定量分析屯小鼠海马ＣＡ３区ＧｒａｙＩ突触界面结构参数的变化。     

On structural models for analyzing change

The recommendation to base the analysis of multi-wave data upon explicit models for change is advocated. Several univariate and multivariate models are described, which emerge from an interaction between the classical test theory and the structural equation modeling approach. The resulting structural models for analyzing change reflect in some of their parameters substantively interesting aspects of intra- and interindividual change in follow-up studies. The models are viewed as an alternative to an ANOVA-based analysis of longitudinal data, and are illustrated on data from a cognitive intervention study of old adults (Bakes et al , 1986). The approach presents a useful means of analyzing change over time, and is applicable for purposes of (latent) growth curve analysis when analysis of variance assumptions are violated (e.g., Schaie & Hertzog, 1982; Morrison, 1976).