Accounting for Uncertainty in Heteroscedasticity in Nonlinear Regression

Toxicologists and pharmacologists often describe toxicity of a chemical using parameters of a nonlinear regression model. Thus estimation of parameters of a nonlinear regression model is an important problem. The estimates of the parameters and their uncertainty estimates depend upon the underlying error variance structure in the model. Typically, a priori the researcher would not know if the error variances are homoscedastic (i.e., constant across dose) or if they are heteroscedastic (i.e., the variance is a function of dose). Motivated by this concern, in this paper we introduce an estimation procedure based on preliminary test which selects an appropriate estimation procedure accounting for the underlying error variance structure. Since outliers and influential observations are common in toxicological data, the proposed methodology uses M-estimators. The asymptotic properties of the preliminary test estimator are investigated; in particular its asymptotic covariance matrix is derived. The performance of the proposed estimator is compared with several standard estimators using simulation studies. The proposed methodology is also illustrated using a data set obtained from the National Toxicology Program.     

Lagrange multiplier unit root test in the presence of a break in the innovation variance

We show that the Lagrange multiplier (LM) unit root test exhibits size distortions when a break in the innovation variance exists but is ignored. We develop a modified LM unit root test that is based on a generalized least-squares transformation of the original series. The asymptotic null distribution of the new modified LM unit root test is derived. Finite-sample simulation evidence shows that the modified LM unit root test maintains its size and has reasonable power against the trend stationary alternative.     

Methodological Validation of Quality of Life Questionnaire for Coal Mining Groups-Indian Scenario

Maslow’s hierarchy-of-needs theory has been used to predict development of Quality of Life (QOL) in countries over time. In this paper an attempt has been taken to derive a methodological validation of quality of life questionnaire which have been prepared for the study area. The objective of the study is to standardize a questionnaire tool to assess the QoL of residents in a problem area in India. From a pre tested 16 parameter questionnaire tool factorial validity were established to extract three domains and were mapped in accordance to Abraham Maslow’s Hierarchy of Needs theory. Out of these 16 parameters 13 were found relevant. Then a new tool was conceptualized with 13 pre selected parameters and other parameters were pooled from existing tool and reviews to form a 36 parameter tool. Factor analysis was done to extract the domains. Reliability of the tool was also tested to find the relation between the domains of QoL. Then the quality of life of the study area was interpreted to find the distribution of respondents among the categories of QoL. 70% of respondents reported to have average quality of life. The tool was found to be highly reliable and valid.     

人机系统中作业者心理负荷问题研究综述及展望

心理负荷既是效率问题,更重要的是安全问题。由于机器自动化、知识经济和信息社会的快速发展,效率问题得到有效的解决,而人的心理健康以及职业安全问题则日益突出,造成这种状况的根本原因就是沉重的心理负荷。从20世纪70年代以来,众多研究者力图去定义心理负荷,后来发现只能下＂操作化定义＂。以威肯斯（C.D.Wickens,1984,2002）为代表的一些研究者找到了更有效的研究方法,即通过模型去进行测评研究。后来的研究不再把心理负荷作为纯效率问题,而是作为身心健康问题进行研究。本文认为,心理负荷的测评应该成为安全职业适应性的核心内容。     

On coupling particle filter trajectories

Particle filters are a powerful and flexible tool for performing inference on state-space models. They involve a collection of samples evolving over time through a combination of sampling and re-sampling steps. The re-sampling step is necessary to ensure that weight degeneracy is avoided. In several situations of statistical interest, it is important to be able to compare the estimates produced by two different particle filters; consequently, being able to efficiently couple two particle filter trajectories is often of paramount importance. In this text, we propose several ways to do so. In particular, we leverage ideas from the optimal transportation literature. In general, though computing the optimal transport map is extremely computationally expensive, to deal with this, we introduce computationally tractable approximations to optimal transport couplings. We demonstrate that our resulting algorithms for coupling two particle filter trajectories often perform orders of magnitude more efficiently than more standard approaches.     

Migration,Poverty, and Risk of HIV Infection: An Application of Social Capital Theory

A majority of current HIV/AIDS interventions are designed primarily after individual-based public health models and pay little attention to the socioeconomic environment in which HIV transmission occurs. This article focuses on outlining how migration acts as a conduit for disease transmission in South Africa and then proposes a macro-level prevention model based on social capital theory, thus then supplementing current prevention literature. It is based on the argument that social disruption and stresses from migration lead to sexual interactions during the migration periods that amplify the risk of HIV transmission among migrants.     

线上绘图教学法在系统解剖学神经系统中的应用研究

系统解剖学是重要的医学基础课,但是由于解剖学需要记忆的内容较多,学生无法精确掌握正常人体结构的立体形态,无法构建完整的医学知识构架.为了帮助学生理解记忆,在教学中引入绘图教学法.绘图教学法结合其他记忆方法,应用于系统解剖学神经系统线上教学中,使复杂枯燥的神经系统内容简单化、具体化,对学生学习神经系统有很大帮助,该研究旨在为神经系统教学方法提供一点借鉴.     

一个低视力孩子随班就读的叙事研究

本文采取叙事研究的方法,通过一个低视力孩子对自身随班就读经历和抉择的自叙,探讨影响随班就读有效性的因素.研究表明:随班就读的政策落实有待加强;融洽的同伴和师生关系给予个体积极的支持;支持环境的创设给予个体更多参与的机会;改革评价方式以减轻个体负担;教育施与受关系应和谐;应高效利用普校的丰富资源.     

构建动态多维的外语教学评价体系

现有的外语教学评价体系各有侧重,不能全面体现多元评价与发展评价的基本原则。依据当代评价理论、建构主义学习理论和“以人为本”教育理念,遵循效度原则、信度原则、全面性原则和可持续发展原则,构建了动态多维的外语教学评价体系,该体系体现了评价的互动性、历时性、融合性与多维性特征,对外语教学中评价的实施具有理论指导意义。