Conditional Functional Principal Components Analysis

Abstract.  This work proposes an extension of the functional principal components analysis (FPCA) or Karhunen–Loève expansion, which can take into account non-parametrically the effects of an additional covariate. Such models can also be interpreted as non-parametric mixed effect models for functional data. We propose estimators based on kernel smoothers and a data-driven selection procedure of the smoothing parameters based on a two-step cross-validation criterion. The conditional FPCA is illustrated with the analysis of a data set consisting of egg laying curves for female fruit flies. Convergence rates are given for estimators of the conditional mean function and the conditional covariance operator when the entire curves are collected. Almost sure convergence is also proven when one observes discretized noisy sample paths only. A simulation study allows us to check the good behaviour of the estimators.     

美国高技术城市成功因素探析

美国高技术城市的成功是多种因素综合作用的结果。大学、尤其是高水平的研究型大学不仅是重要的研发资源,而且是高技术企业高素质劳动力和潜在的创业者的主要来源。风险投资为高技术企业注入资金,参与运营,起着积极的推动作用。美国联邦政府的国防开支和其他领域的研发开支、州政府的诸多举措均有力地推动了高技术城市的发展。城市的集聚效应也发挥了明显的作用,是讨论美国高技术城市成功不可或缺的重要因素。此外,美国高技术城市生活质量在吸引高素质人才方面的优势也不容忽视。     

The effects of job displacement on job quality: Findings from the Wisconsin Longitudinal Study

This study examines the extent to which job displacement divides the career experiences for a cohort of workers. Previous studies of job displacement find nontrivial economic losses for displaced workers, but the effects of displacement on “non-economic” properties of jobs have been largely overlooked. Results using the Wisconsin Longitudinal Study indicate that workers who were displaced have lower levels of occupational status, job authority, and employer-offered pension and health insurance than they would have had had they not been displaced. Difference-in-differences estimates, which control for temporally-invariant unobserved heterogeneity, are generally larger than cross-sectional estimates; still, there is a close correspondence of estimates across a range of methodological approaches attesting to the robustness of the estimates in the face of various technical assumptions and model specifications. Effects of displacement on job quality also exhibit conditioning by gender, education, occupation, and industry: while less educated, blue collar and manufacturing workers experience significant losses for employer-offered benefits, more educated, upper white collar and non-manufacturing workers experience significant losses for occupational status, job autonomy, and job authority.     

目击事件对目击证人记忆的错误信息效应研究

通过操作误导事件后的信息这一变量,考察有无误导事件后的信息对目击证人原始事件记忆效果的影响,以及目击证人对自己回答的自信心方面的影响。实验结果表明:(1)误导事件后的信息使被试对原始事件产生错误记忆;(2)误导事件后的信息对主体问题没有影响,但对情境问题的影响达到显著水平;(3)是否接受误导事件后的信息与目击证人的自信之间没有相关,但是不同的问题类型以及是否回答正确,与目击证人的自信有密切关系。     

大学生考研热透析

文章分析了当前考研热中考生的各种动机和心态，并从端正学风、班风、校风的角度分析了大学生考研对考研生本人的积极作用以及对考研生所在班集体的积极的影响作用，指出了目前考研热中存在的一些问题。     

基于面板数据的中国农业信贷绩效研究

文章基于面板数据,利用固定效应估计法和随机效应估计法,对我国在1999年至2002年间农业信贷的绩效作出实证研究。研究结果表明,我国农业信贷配置机制应作进一步的调整,以便提高农业信贷的绩效,支持农业发展。     

Effects of non-normality on the power function in a one-way random model

The effects of non-normality on type-I and type-II errors in a one-way random model are investigated for moderate departures from normality. It is found that the probabilities of both errors are more sensitive to the kurtosis of between group effects than that of within group effects.     

The Management of Risk: Application to the Welding Industry

The management of health risk in the welding industry is considered based on a discussion of the major sources of harm to welders arising from their employment (e.g., accidents and inhalation of fumes and gases). It is shown that present methods neither enable the assessment of the societal and human costs involved, nor permit the specific association of delayed health effects to occupational fume exposures. Reported accidents usually occur early in the working experience and contribute to a large number of working days lost, while fume exposures may contribute to a reduction in life quality which is poorly defined. It is concluded that risk management can only be attempted after much more information is made available concerning the origin, nature, and duration of health effects, especially as related to individual welding technologies and applications.     

NEIGHBOUR ANALYSIS WITH ADJUSTMENT FOR INTERPLOT COMPETITION

In field experiments involving a large number of experimental plots, a neighbour analysis can be used to control environmental variation by estimating the trend within blocks. The effect of interplot competition is another important source of variation which has an influence on the estimation of treatment contrasts. To reduce the effect of the variation from these sources and to improve the precision of comparison between treatments, a spatial model is proposed for incorporating both trend effect and interplot competition. It is a modification to the residual maximum likelihood neighbour analysis of Gleeson & Cullis (1987) using the two neighbouring treatment effects to estimate interplot competition. A real example is used to illustrate this methodology. The results indicate that the extended model gives no appreciable difference in standard error of mean differences compared with the model taking into account the trend effect only. However, the rankings of estimated treatment means do differ. More research using both real and simulated data is required before such models that incorporate trend and competition effects can be confidently recommended.     

变离心力场中等截面冷却通道的流量计算和实验研究

本文用数值计算得到的数据集，回归出在变离心力场下，等截面管流由于热阻力引起的变密度流流量减少公式，并用热平衡法在旋转试验台上测量了加热条件下通道内的加热量和平均流速．由实验数据集回归出的流量减少公式与数值计算结果相符．