A new quantitative method for assessing sleepiness: The alpha attenuation test

Abstract

Sleepiness interferes with the ability of night-workers and shiftworkers to safely and effectively perform their jobs, and has been increasingly recognized as a major cause of industrial and transportation accidents. Current methods for the assessment of physiological sleepiness levels, such as the Multiple Sleep Latency Test (MSLT) have several limitations and are particularly impractical in field or occupational studies. In this study, the effectiveness of the Alpha Attenuation Test (AAT) for the quantification of sleepiness has been evaluated and compared to the MSLT during a 40-h sleep deprivation protocol. The AAT, a 12-min eye closed/open protocol, is a quantitative method based on the fact that EEG alpha (8-12 Hz) activity tends to increase with eyes open as individuals get sleepier, while it decreases with eyes closed. In this validation study, the AAT proved to be a sensitive measure of sleepiness induced by sleep deprivation, and it also correlated well with the MSLT. Relative to the MSLT, the AAT has the advantages of being objective, minimally intrusive, and more practical especially in industrial or field studies.     

高校英语专业口语教学主要问题研究

口语是英语专业基础课程之一,与听、读、写、译具有同等重要的地位。笔者结合多年英语专业口语教学实际,从教材适用性、教师口语水平、学生态度和水平测试四个方面分析了高校英语专业口语教学中存在的主要问题,说明了英语专业学生口语能力难以快速提高的症结所在,目的是引导教师和学生加强对口语课教学的反思和研究。     

A test for the parametric form of the variance function in a partial linear regression model

We consider the problem of testing for a parametric form of the variance function in a partial linear regression model. A new test is derived, which can detect local alternatives converging to the null hypothesis at a rate n^-1/2$n^{-1/2}$ and is based on a stochastic process of the integrated variance function. We establish weak convergence to a Gaussian process under the null hypothesis, fixed and local alternatives. In the special case of testing for homoscedasticity the limiting process is a scaled Brownian bridge. We also compare the finite sample properties with a test based on an L²$L^2$-distance, which was recently proposed by You and Chen [2005. Testing heteroscedasticity in partially linear regression models. Statist. Probab. Lett. 73, 61–70].     

基于VAR模型的四川经济增长与投资消费关系实证研究

选取1990-2010年四川省经济数据,运用格兰杰因果检验、VAR模型和脉冲响应分析等方法对四川省经济增长与投资消费之间的关系进行了实证研究,结果表明：不论时间长短,投资水平对经济增长和消费水平的影响相对显著,而经济增长和消费水平在短期内对其他两项的影响不显著。     

论大学英语词汇教学

英语语言学家威尔金斯对词汇的定义和最新颁布的《大学英语课程教学要求(》试行)对大学英语词汇教学的要求,都阐释了词汇在大学英语教学中的重要性。文章介绍了现阶段大学英语教学的情况,并通过调查分析,发现以大学英语四、六级考试为目的的大学英语词汇教学的弊病,提出科学的词汇教学方法,并对词汇教学与大学英语教学之间的关系进行了阐释。     

Estimating probabilities from invariant permutation distributions

Summary We introduce variance reduction techniques as general tools for estimating probabilities from invariant permutation distributions. The paper discusses importance sampling, antithetic sampling and control variates sampling as alternatives to uniform Monte Carlo sampling for estimating exact critical values orP-values in a broad class of permutation tests. Results may be extended to permutation confidence intervals and linear rank tests. An asymptotic theory is provided for each proposed variance reduction method. Invited paper at the Conference held in Bologna, Italy, 27–28 May 1993, on ?Statistical Tests: Methodology and Econometric Applications?.     

A test of the normality assumption in ordered probit model

This paper presents a Lagrange multiplier test of the normality assumption underlying the ordered probit model. The test is presented both for the standard ordered probit model and a version in which censoring is present in the dependent variable. The test is then compared to normality tests proposed here compares favorably to tests based on artificial regression techinques.     

A monte carlo comparison of tests based on the durbin-watson statistic with other autocorrelation tests in dynamic models

This paper examines the sampling properties of a number of serial correlation tests in dynamic linear models which include one or two lags of the dependent variable. Among the tests considered are the Durbin-Watson (DW) bounds test, modified versions of the DW proposed recently by King and Wu and Inder, Durbin's m test, Inder's point optimal test and a Hausman type test. Sampling designs include models with one or two lags of the dependent variable. The m, Hausman, and Inder's tests have the best performance, while Inder's modified DW test appears to be better than the other DW based tests. Results also suggest that tests are less powerful and more sensitive to design parameters in models with higher dynamics, with the DW-based tests being the most sensitive.     

Bootstrapping a consistent nonparametric goodness-of-fit test

In this paper, we employ the parametric bootstrap to approximate the finite sample distribution of a goodness-of-fit test statistic in Fan (1994). We show that the proposed bootstrap procedure works in that the bootstrap distribution conditional on the random sample tends to the asymptotic distribution of the test statistic in probability. A simulation study demonstrates that the bootstrap approximation works extremely well in small samples with only 25 observations and is very robust to the value of the smoothing parameter in the kernel density estimation.     

地方保护主义和地区间贸易壁垒的检验性分析

随着市场经济的发展,贸易作为经济运行中的一个环节,其重要性越来越凸现出来,而阻碍贸易正常进行的地方保护主义和贸易壁垒对宏观经济的良性发展起到了消极的作用。准确把握我国地方保护主义和地区间贸易壁垒的现状意义重大。本文基于国务院发展研究中心发展战略和区域经济研究部与北京大学光华管理学院所作的“地区间经济联系障碍的调查问卷”,对前期回收的有效样本,运用统计检验分析的方法,就当前地方保护和贸易壁垒的存在性以及企业的不同类型是否与其面临的地方保护和贸易壁垒有程度上的关联等问题做了相关研究,认为企业的规模和所有制性质对企业面临的地方保护和贸易壁垒基本没有程度上的影响;同时,统计分析结果还表明目前国内地区间贸易壁垒偏重于无形和隐形的形式。