微乳液聚合制备聚丙烯酰胺及聚N-异丙基丙烯酰胺超细微粒

研究了琥珀酸双（２－乙基己酯）磺酸钠（ＡＯＴ）、甲苯（Ｔ）、乙酰胺（ＥＭ）、丙烯酰胺（ＡＭ）、Ｎ－异丙基丙烯酰胺（ＮＩＰＡＭ）、Ｎ,Ｎ－亚甲基双丙烯酰胺（ＢＩＳ）、水组成的六种微乳液体系,以电导法和目视法测定了其相区临界点电导率,并绘制了各自的拟三元相图;以偶氮二异丁腈（ＡＩＢＮ）为引发剂,在微乳液中制备了聚丙烯酰胺及聚Ｎ－异丙基丙烯酰胺超细微粒．用ＩＲ谱对其进行了验证,以扫描电镜观察了其外部结构特征,测得微粒平均粒径为０．０５～０．１０μｍ．实验表明,可在微乳液中制备ＰＡＭ及ＰＮＩＰＡＭ超细微粒．     

The Singularity of the Information Matrix of the Mixed Proportional Hazard Model

This paper presents new identification conditions for the mixed proportional hazard model. In particular, the baseline hazard is assumed to be bounded away from 0 and ∞ near t = 0. These conditions ensure that the information matrix is nonsingular. The paper also presents an estimator for the mixed proportional hazard model that converges at rate N^−1/2.     

“A＋N”的认知研究

文章从认知语言学的角度出发,对＂A＋N＂结构进行全面的考察,包括原型理论、构式、隐喻、成分意义等。指出＂,A＋N＂结构从一个侧面反映了人类认知的体验基础,以及认知遵循的从简单到复杂、从客观到主观的基本规律,而隐喻则是人类认识不断深化的重要机制之一。隐喻具有突破语义限制的作用,其产生的结果可使＂A＋N＂的意义固化,从而形成习语和惯用语。     

Nonparametric covariate adjustment for receiver operating characteristic curves

The accuracy of a diagnostic test is typically characterized using the receiver operating characteristic (ROC) curve. Summarizing indexes such as the area under the ROC curve (AUC) are used to compare different tests as well as to measure the difference between two populations. Often additional information is available on some of the covariates which are known to influence the accuracy of such measures. The authors propose nonparametric methods for covariate adjustment of the AUC. Models with normal errors and possibly non‐normal errors are discussed and analyzed separately. Nonparametric regression is used for estimating mean and variance functions in both scenarios. In the model that relaxes the assumption of normality, the authors propose a covariate‐adjusted Mann–Whitney estimator for AUC estimation which effectively uses available data to construct working samples at any covariate value of interest and is computationally efficient for implementation. This provides a generalization of the Mann–Whitney approach for comparing two populations by taking covariate effects into account. The authors derive asymptotic properties for the AUC estimators in both settings, including asymptotic normality, optimal strong uniform convergence rates and mean squared error (MSE) consistency. The MSE of the AUC estimators was also assessed in smaller samples by simulation. Data from an agricultural study were used to illustrate the methods of analysis. The Canadian Journal of Statistics 38:27–46; 2010 © 2009 Statistical Society of Canada     

Smoothed empirical likelihood confidence intervals for the relative distribution with left‐truncated and right‐censored data

The study of differences among groups is an interesting statistical topic in many applied fields. It is very common in this context to have data that are subject to mechanisms of loss of information, such as censoring and truncation. In the setting of a two‐sample problem with data subject to left truncation and right censoring, we develop an empirical likelihood method to do inference for the relative distribution. We obtain a nonparametric generalization of Wilks' theorem and construct nonparametric pointwise confidence intervals for the relative distribution. Finally, we analyse the coverage probability and length of these confidence intervals through a simulation study and illustrate their use with a real data set on gastric cancer. The Canadian Journal of Statistics 38: 453–473; 2010 © 2010 Statistical Society of Canada     

China's energy inefficiency: A cross-country comparison

This paper constructs a total-factor energy technical efficiency index using the data envelopment analysis (DEA) method following the total factor productivity framework. We then compare energy technical efficiency across 156 countries from 1980 to 2007. The results show that China's energy efficiency considerably trails other countries’ although it has made significant gains within the last 28 years. Further analysis indicates that scale inefficiency rather than pure technical efficiency contributes to China's energy inefficiency.     

A generalized Fleming and Harrington's class of tests for interval‐censored data

The class $G^{\rho,\lambda }$ of weighted log‐rank tests proposed by Fleming & Harrington [Fleming & Harrington (1991) Counting Processes and Survival Analysis, Wiley, New York] has been widely used in survival analysis and is nowadays, unquestionably, the established method to compare, nonparametrically, k different survival functions based on right‐censored survival data. This paper extends the $G^{\rho,\lambda }$ class to interval‐censored data. First we introduce a new general class of rank based tests, then we show the analogy to the above proposal of Fleming & Harrington. The asymptotic behaviour of the proposed tests is derived using an observed Fisher information approach and a permutation approach. Aiming to make this family of tests interpretable and useful for practitioners, we explain how to interpret different choices of weights and we apply it to data from a cohort of intravenous drug users at risk for HIV infection. The Canadian Journal of Statistics 40: 501–516; 2012 © 2012 Statistical Society of Canada     

Making hermeneutics explicit: how QCA supports an insightful dialogue between theory and cases

Typically, qualitative comparative analysis (QCA) is praised for its hermeneutic dialogue between theory and empirical cases. However, in reporting research with QCA, these hermeneutic processes will usually not be illustrated. This paper aims at showing clear how QCA induces this dialogue between theory and data. As an illustrative example, I use a research situation dealing with a genuine research question of Legislative Studies: the causes of party unity. Using the classical dichotomous and the MV-QCA approach, the paper mainly shows how to deal productively with contradictory theoretical statements and how stepping from simpler to more complex models adds explanation while still making clear further routes to improve insights into the substantive research topic: both theoretically and empirically. Finally, non-observed configuration (‘logical remainders’) will be used to simplify the resulting theory, and its theoretical and empirical plausibility will be evaluated. The whole paper makes explicit how the QCA approach forces researchers to reveal the dialogue between theory and cases – just as it was intended by the inventor of this analytical tool.     

Vertical foodweb structure of freshwater zooplankton assemblages estimated by stable nitrogen isotopes

Although theoretical foodweb models predict the presence of only three to four trophic categories, estimation of “potential” vertical foodweb structure from species lists and inferred feeding interactions suggest that as many as 7 trophic categories can occur in the pelagic foodwebs of North American glaciated lakes. A compilation of data on the nitrogen isotopic composition of zooplankton from 46 Canadian Shield lakes suggested the average existence of one “realized” trophic category in addition to that of filter-feeding, herbivorous cladocerans. When phytoplankton, planktivorous invertebrates, and plantivorous and piscivorous fish are included, the vertical foodweb structure in the pelagic zones of these lakes are greater than those hypothesized from some theoretical models.