Effects of repetition and consistency of personalization treatments on response rate in mail surveys

One unequivocal finding of past research has been that follow-ups improve response rates in mail surveys. Several ways to construct sophisticated data collection systems using follow-ups in combination with other response-improving techniques are discussed, giving rise to the issue of whether repetition of techniques in each follow-up is more effective than single use in the first mailing. Two experiments were conducted to examine the effects of repeated versus single implementation of personalization of the outside envelope. A consistent use of personalization procedures in each mailing obtained a higher response rate than an inconsistent one, consisting of personalization of the first mailing with impersonal follow-ups. A second experiment showed repeated personalization to be more effective than repeated impersonal mailings.     

Fe3O4负载纳米TiO2的微乳液法制备与表征

采用油酸/正丁醇/NaOH溶液制备了Fe3O4负载纳米TiO2.用微乳体系制备出纳米二氧化钛前驱体,然后由表面活性剂稳定和保护的纳米粒子在氢键吸附等作用力下包覆于Fe3O4载体的表面.用热重-差热分析、扫描电镜(SEM)、红外光谱法和X-射线衍射(XRD)对其结构进行分析.SEM和XRD的结果表明,所制得TiO2粒子为锐钛矿晶型,粒径为15 nm左右,呈球形分布于Fe3O4表面.用分光光度法测得TiO2的包覆率为34.2%.     

从晚清到“五四”——近现代报刊在中国现代儿童观生成中的作用

中国现代儿童观的生成走过了从晚清到"五四"的历史阶段,梁启超等对儿童重要性的张扬,使儿童走出了成人高大背影的遮掩;周作人、鲁迅"儿童本位"论的提出,完成了具有现代品格的儿童观的塑造,而这一过程的得以顺利进行,则借助于<清议报>、<新青年>等报刊的合力扶持.     

"五四"女作家笔下"贤妻良母"的新内涵

"贤妻良母"曾一度被看成是封建女性的代名词.冰心、陈衡哲等"五四"女作家根据自己的人生体验,理智、谨慎地对民族、文化、历史进行审视和反省,扬弃了传统的女性角色.她们对女性标准人格和角色定位做出了准确把握,从思想基础、自身修养和社会尊重等三个方面赋予了贤妻良母新内涵,在文化观念方面为女性解放创造了良好条件.     

Nd:GdYVO4与Nd:YVO4的激光倍频特性比较

在相同实验条件下,采用V型折叠腔对比了Nd:GdYVO4和Nd:YVO4两种晶体的腔内倍频特性。利用KTP腔内倍频,在泵浦功率为6.71W时分别获得了1.69W和1.46W的稳定倍频绿光输出,光-光转换效率分别达到25.2%和21.8%。比较得出,由于Nd:GdYVO4晶体良好的导热性,在大功率激光泵浦条件下,Nd:GdYVO4/KTP获得了更好的倍频激光输出。     

“五四”前后北京大学世界语传播概述

世界语(Esperanto)清末传入中国,但真正在中国得到推广却是在“五四”新文化运动时期。北京大学作为新文化运动及“五四”运动的摇篮,对于世界语这种外来语进行了不遗余力的宣传推广,并走出校园,到民众中进行宣传,从而为世界语运动在中国的开展奠定了基础。“五四”新知识分子的世界主义观念则是世界语在中国得以大力推广并形成社会运动的思想基础。     

大学英语四级统考效应浅析

大学英语四级考试是大学英语教学过程中的辅助手段，它会对大学英语教学起着积极有益的促进作用和消极有害的反拨作用。从四级考试效应分析中，我们发现考生的四级考试成绩与他们时真实水平不相符。我们要充分利用考试的积极效应来改进大学英语的教学方式、提高我们的大学英语教学水平。     

Gaussian models for degradation processes-part I: Methods for the analysis of biomarker data

We present two stochastic models that describe the relationship between biomarker process values at random time points, event times, and a vector of covariates. In both models the biomarker processes are degradation processes that represent the decay of systems over time. In the first model the biomarker process is a Wiener process whose drift is a function of the covariate vector. In the second model the biomarker process is taken to be the difference between a stationary Gaussian process and a time drift whose drift parameter is a function of the covariates. For both models we present statistical methods for estimation of the regression coefficients. The first model is useful for predicting the residual time from study entry to the time a critical boundary is reached while the second model is useful for predicting the latency time from the infection until the time the presence of the infection is detected. We present our methods principally in the context of conducting inference in a population of HIV infected individuals.     

五四时期马克思主义传播历史特点平议

五四时期马克思主义传播有三个突出特点 :不是没有真理性的强意识形态化 ,而是具有符合中国反帝反封建斗争需要的彻底革命性 ,是马克思主义作为真正揭示中国革命规律的思想武器被中国人民接受 ;不是对外排斥一切文化、对内拒绝自我更新 ,而是具有科学的开放性 ,对外积极吸收其他文化优秀成分 ,对内不断自我更新 ;不是排斥知识分子 ,也不是强迫知识分子向落后的农民认同 ,而是具有主体的大众性 ,以具有初步共产主义思想的知识分子为桥梁 ,迅速与工人运动相结合并影响农民运动 ,从而实现了以中国人民为实践主体。     

The Double Gaussian Approximation for High Frequency Data

Abstract High frequency data have become an important feature of many areas of research. They permit the creation of estimators in highly non‐parametric classes of continuous‐time models. In the context of continuous semi‐martingale models, we here provide a locally parametric ‘double Gaussian’ approximation, to facilitate the analysis of estimators. As in Mykland and Zhang (Econometrica, 77, 2009, p. 1403), the error in the approximation can be offset with a postasymptotic likelihood correction. The current approximation is valid in large neighbourhoods, permitting a sharp analysis of estimators that use local behaviour over asymptotically increasing numbers of observations.