Robust estimator design with an emphasis balance between performance and robustness

From a number of ML estimators (typically unbiased) of practical interest which include the variance for a Gaussian distribution, the standard deviation for a Laplace distribution, the variance for a Rayleigh distribution and a “spread parameter” for a Cauchy distribution, we design robust estimators according to an emphasis balance between normalized performance and normalized robustness. We measure performance with inverted MSE and robustness with a differential geometric approach.     

分数阶微分方程初值问题解的存在性

利用Leray-Schauder度理论,证明了Caputo和Remann-Liouville分数阶微分方程初值问题解的存在性。     

从微分方程的角度谈共振

本文以一道物理问题—数学摆的微小震动为例,结合质点的振动理论,建立微分方程,并且根据其解的形式,说明共振现象发生的原因。然后,针对与共振相关的生活问题和灾难问题,提出预防措施.     

Teacher classroom interactions and behaviours: Indications of bias

In some recent studies, researchers have measured teacher implicit bias and some have shown that teacher bias predicts student academic outcomes. Currently, however, how bias is portrayed to individual students is largely unknown. In this exploratory qualitative study, observations totalling 4 h per participant were undertaken with ten secondary, six intermediate, and four primary teachers in New Zealand. We utilised a thematic analysis approach to identify three themes: “differential nonverbal behaviours”, “differential academic interactions” and “differential reactions under the same conditions” that captured teachers' classroom interactions. Our findings suggested that teachers’ differential behaviours were mediating teacher bias. This was because teacher bias was recorded in every classroom; however, teachers displayed biased behaviours to varying degrees. Bias was displayed through various nonverbal and academic interactions, and some teachers portrayed their bias by treating some students differently when the situation for all students was the same.     

一类高阶超越亚纯函数系数微分方程解的增长性

研究了一类微分方程f（k）＋A（z）f＊＋B（z）f=0亚纯解的增长性,其中A（z）,B（z）为有限级的超越亚纯函数,F为有限级亚纯函数.研究了微分方程亚纯解的不动点与超级,得到了进一步的结果.     

应用型本科院校《常微分方程》课程教学改革的思考

根据应用型本科院校的培养目标,结合当前《常微分方程》课程学时不足、课程内容与结构体系相对滞后、过分强调知识的系统性、教学模式固定、教学手段单一等现状,在教育理念、课程内容、教学方法以及教学手段等方面提出一系列的改革措施,以促进大学生独立思考能力和创新能力的培养,提高课堂教学质量,达到培养高素质应用型人才的目的。     

论差异机会平等与政府民生政策的实施

差异机会平等是指社会成员之间的生存与发展机会的不完全相等性,存在程度上的差别。政府的各项民生政策的实施要以差异机会平等为前提,要高扬自由、平等理念,确立自致性、能力本位的价值取向;完善公平公正的体制机制,大力发展教育尤其是基础教育事业,把促进公平作为国家基本教育政策。     

TBZ在MWCNT—DHP膜修饰电极上的电化学分析研究

在pH：2．0的B—R（Britton—Robinson）的缓冲溶液中,对制备的多壁碳纳米管,双十六烷基磷酸（MwcNT—D船）膜修饰电极进行了循环伏安法（CV）表征;分别研究了涕必灵（1BZ）在裸玻碳电极（GcE）和MWCNT—DHP膜修饰电极上的电化学行为,采用微分脉冲伏安法（DTV）,以MWCNT—DHP膜修饰电极为工作电极,建立了一个简单、快速、灵敏的涕必灵电化学分析检测体系;并结合固相萃取技术,测定了环境水中涕必灵含量,检测限达到2．0×10-8mol·L-1,平均回收率为97．28％-99．40％,RSD为1．3％～2．8％（n=6）。     

Estimation of MIMIC Model Parameters with Multilevel Data

The purpose of this simulation study was to assess the performance of latent variable models that take into account the complex sampling mechanism that often underlies data used in educational, psychological, and other social science research. Analyses were conducted using the multiple indicator multiple cause (MIMIC) model, which is a flexible and effective tool for relating observed and latent variables. The data were simulated in a hierarchical framework (e.g., individuals nested in schools) so that a multilevel modeling approach would be appropriate. Analyses were conducted accounting for and not accounting for the nested data to determine the impact of ignoring such multilevel data structures in full structural equation models. Results highlight the differences in modeling results when the analytic strategy is congruent with the data structure and what occurs when this congruency is absent. Type I error rates and power for the standard and multilevel methods were similar for within-cluster variables and for the multilevel model with between-cluster variables. However, Type I error rates were inflated for the standard approach when modeling between-cluster variables.     

Is academic tracking related to gains in learning competence? Using propensity score matching and differential item change functioning analysis for better understanding of tracking implications

This study analyzes gains in cognitive components of learning competence with respect to cohorts based on ability tracking in a Czech longitudinal study. Propensity score matching is used to form parallelized samples of academic and non-academic track students and to eliminate the effect of selective school intake. We applied regression models on the total scores to test for the overall track effect. Furthermore, we analyze scores and gains on the subscores and check for differential item functioning in Grade 6 and in change to Grade 9. While after 3 years, no significant difference between the two tracks was apparent in the total learning competence score, we did, however, find significant differences in some subscores and in the functioning of some items. We argue that item-level analysis is important for deeper understanding of the tracking implications and may provide the basis for more precise evidence-based decisions regarding the tracking policy.