Do Drivers of Small Cars Take Less Risk in Everyday Driving?

Previously reported observed data on risky everyday driving are brought together and reanalyzed in order to focus on the relation between risky driving and the size of the car being driven, as indicated by car mass. The measures of risky driving include separation between vehicles in heavy freeway traffic and speed on a two lane road. Observed seat belt use provides a third measure of driver risk. Confounding effects arising from the observed association between car mass and driver age are taken into account by segmenting the data into three driver age groups. Driver risk taking is found to increase with increasing car mass for each of these three aspects of everyday driving. The implications of these results with respect to driver fatality rates are discussed in terms of a simple model relating observed risky driving to the likelihood of involvement in a severe crash.     

定位误差的简明计算研究

主要阐述了定位误差的基本概念和分析计算方法，并举例说明其运用.     

Women's Scientific Employment and Family Formation: A Longitudinal Perspective

We focus here on the retention of highly qualified women scientists in science‐based employment in England and Wales. Using linked Census records from the Longitudinal Study 1971–1991 we show that women's education and employment rates in science, engineering and technology increased somewhat, although some fields show persistently low representation. We then compare retention in employing women with health‐related degrees with that of women with degrees in science, engineering and technology, showing that the latter group has markedly lower retention rates. Those who stay on in science‐based employment have children later than other types of graduate and their rates of non‐motherhood are higher. Four‐fifths of women in health‐related occupations were mothers, compared to only two‐fifths in science, engineering and technology. Our findings have implications for policymakers who wish to make best use of the knowledge base: attention should be paid to retention, as well as the more usual focus on qualifications and recruitment. The findings also suggest the potential for institutionally based theories to explain why highly qualified women have such low retention rates in science‐based employment.     

从尘埃里开出花来——论张爱玲小说中的“居室经验”

以文本细读为研究方法,分析了张爱玲小说中具有古旧风韵的“居室经验”,指出其“居室经验”具体体现为败落的家庭生活场景、旧势家族的“礼仪道德”以及冰冷的人情感受,所以,“居室经验”是张爱玲小说中最有意味的部分,也是其民间姿态的一种坚守方式。     

A new class of measurement-error models,with applications to dietary data

Measurement-error modelling occurs when one cannot observe a covariate, but instead has possibly replicated surrogate versions of this covariate measured with error. The vast majority of the literature in measurement-error modelling assumes (typically with good reason) that given the value of the true but unobserved (latent) covariate, the replicated surrogates are unbiased for latent covariate and conditionally independent. In the area of nutritional epidemiology, there is some evidence from biomarker studies that this simple conditional independence model may break down due to two causes: (a) systematic biases depending on a person's body mass index, and (b) an additional random component of bias, so that the error structure is the same as a one-way random-effects model. We investigate this problem in the context of (1) estimating distribution of usual nutrient intake, (2) estimating the correlation between a nutrient instrument and usual nutrient intake, and (3) estimating the true relative risk from an estimated relative risk using the error-prone covariate. While systematic bias due to body mass index appears to have little effect, the additional random effect in the variance structure is shown to have a potentially important effect on overall results, both on corrections for relative risk estimates and in estimating the distribution of usual nutrient intake. However, the effect of dietary measurement error on both factors is shown via examples to depend strongly on the data set being used. Indeed, one of our data sets suggests that dietary measurement error may be masking a strong risk of fat on breast cancer, while for a second data set this masking is not so clear. Until further understanding of dietary measurement is available, measurement-error corrections must be done on a study-specific basis, sensitivity analyses should be conducted, and even then results of nutritional epidemiology studies relating diet to disease risk should be interpreted cautiously.     

Transformations for Smooth Regression Models with Multiplicative Errors

We consider whether one should transform to estimate nonparametrically a regression curve sampled from data with a constant coefficient of variation, i.e. with multiplicative errors. Kernel-based smoothing methods are used to provide curve estimates from the data both in the original units and after transformation. Comparisons are based on the mean-squared error (MSE) or mean integrated squared error (MISE), calculated in the original units. Even when the data are generated by the simplest multiplicative error model, the asymptotically optimal MSE (or MISE) is surprisingly not always obtained by smoothing transformed data, but in many cases by directly smoothing the original data. Which method is optimal depends on both the regression curve and the distribution of the errors. Data-based procedures which could be useful in choosing between transforming and not transforming a particular data set are discussed. The results are illustrated on simulated and real data.     

再谈汉日翻译中的几个问题——再与迟军先生商榷

针对迟军先生于1990年在《日语学习与研究》第3期上发表的“试析《试析〈汉译日基础教程〉的误译》”一文，从如下几个方面与迟军先生再商榷：一、译文要符合语言的规范和表达习惯；二、译文不应使用过于陈旧的词汇或表达方式；三、译文的句组、语段脉络要清楚易懂；四、译文要符合日语语法规范。     

卫星信道基带残留误码分布特性拟合与模拟

卫星通信信道的基带残留误码特性直接影响上层通信协议的性能。通过对卫星通信系统仿真,提取基带误码图案,将基带误码分布图案通过误码持续期发生概率密度分布、误码持续期长度概率密度分布来表征。在典型的卫星通信系统参数条件下,拟合表明经过有噪莱斯衰落信道的误码持续期发生概率接近广义极值分布;经过高斯噪声信道的误码持续期发生概率密度、误码持续期长度概率密度接近负二项式分布。在此基础上完成的卫星基带信道硬件模拟器能够为通信协议的测试提供方便、可信的信道基带特性模拟。     

农业生产与经济增长关系的均衡分析

为探讨我国农业生产与经济增长之间的关系,选取1978-2006年我国历年农业产值和国内生产总值序列进行协整检验,结果表明我国农业生产与经济增长之间存在着长期稳定的动态均衡关系,农业产值每增加1%,将促进经济增长2.12%;误差修正模型表明,农业生产的短期变化对经济增长有显著的正效应,如果本期的经济增长偏离长期均衡值,那么到下一时期这一偏离度将有8%得以纠正;Granger因果关系检验表明,农业生产对经济增长具有短期效应,经济增长对农业生产具有长期促进作用;脉冲响应函数分析和方差分解的结果进一步表明,农业生产对经济增长的贡献较显著。     

Linear Discriminant Analysis of Multivariate Spatial–Temporal Regressions

Abstract.  We consider classification of the realization of a multivariate spatial–temporal Gaussian random field into one of two populations with different regression mean models and factorized covariance matrices. Unknown means and common feature vector covariance matrix are estimated from training samples with observations correlated in space and time, assuming spatial–temporal correlations to be known. We present the first-order asymptotic expansion of the expected error rate associated with a linear plug-in discriminant function. Our results are applied to ecological data collected from the Lithuanian Economic Zone in the Baltic Sea.