Exploring gender gap and school differential effects in mathematics in Chilean primary schools

ABSTRACT

Despite the systematic recognition of large gender gaps in favour of boys in mathematics performance in Chile, the role of schools in explaining this gap has been comparatively underresearched. This paper analyses a longitudinal dataset to explore within- and between-school variation of Chilean primary schools in promoting attainment and progress of girls and boys. In order to reflect the hierarchical nature of the educational data, multilevel modelling is used, with 163,044 students, nested within 3,355 schools, within 310 municipalities to fit raw, contextualised attainment, and value-added models. The weak evidence indicative of gender differential school effect in progress in Chilean primary schools was interpreted as non-substantive. However, differences in effectiveness played a significant role, as girls progressed more than boys in less effective schools, but the opposite was true in more effective schools. Finally, the study concludes that the Chilean gender gap needs to be addressed mainly beyond schools.     

一类多滞量微分方程非负周期解的存在性

利用Leray—Schauder不动点定理，研究了一类多滞量微分方程非负周期解的存在性，得到了一些新的结果并改进了相应的结论．     

无穷时滞泛函微分方程的稳定性

本文改进了文[1]关于无穷时滞泛函微分方程零解一致渐近稳定的定理5,所得结果包含了这一定理及文[2]的定理2。     

60例结核性和新型隐球菌性脑膜炎临床分析

目的：探讨结核性和新型隐球茵性脑膜炎的临床表现、脑脊液和神经影像学鉴别要点。方法：回顾性总结2002年4月至21304年5月收治的31例结核性脑膜炎和29例新型隐球菌性脑膜炎的临床表现、脑脊液及神经影像学特点。结果：结核性脑膜炎多急性起病，发热多在38．50C以上（64．5％），脑脊液蛋白明显升高伴糖和氯化物降低；新型隐球菌性脑膜炎多亚急性起病，进展性头痛，颅高压症状明显，脑脊液压力高，蛋白质轻度升高而葡萄糖明显降低，病原学检查阳性率高。二者神经影像学差异大。结论：根据临床表现和脑脊液常规检查可初步鉴别两种脑膜炎，影像学可提供脑膜或脑实质受累的证据，确诊有赖于及时进行脑脊液病原学检查。     

线性非自治时滞微分方程解的振动性

本文讨论了线性非自治时滞微分方程 x′(t)+sum from i=1 to n p_i(t)x(t-τ_i(t))=0的解的振动性,给出所有解振动的充分条件,改进了文[1,2]的结果.     

A new broadband differential phase shifter fabricated using a novel CRLH structure

Broadband phase shifters are mostly proposed and fabricated based on the scheme proposed by Shiffman, which uses a coupled line with far ends connected together and a uniform transmission line to give a differential phase shift. Based on the unique dispersion property of the composite right/left-handed (CRLH) metamaterial structure, a new configuration is presented in this paper for fabricating the broadband differential phase shifter, which employs a novel CRLH metamaterial structure as one of the differential phase-shift arms, instead of the conventional coupled line. The new circuit can achieve a phase shift of 90° in an operational bandwidth as broad as one octave and its phase deviations are quite small. An original design of the novel broadband phase shifter is presented, in which the artificial CRLH structure was implemented by microstrip quasi-lumped elements. Both the simulated and measured results of the 90° broadband differential phase shifter are presented.     

微小位移检测仪表的设计开发

目前,国内常用的差动变压器式传感器测微仪有指针式和数字式两种,但是存在诸如高精度测量范围小、零位调节不方便、功能单一和通用性差等问题．本文介绍了一种以89C51单片机为核心,采用现有的差动变压器式传感器测头的多功能、智能化测微仪．它具有高精度、智能化、多功能化、操作方便、性能稳定等特点．     

关于微分中值定理"中值点"的个数问题

在微分中值定理“中值点”存在的基础上,进一步研究微分中值定理“中值点”的个数问题.     

差动变压器式位移传感器的设计与实现

分析了LVDT的工作原理、结构组成及特点,和LVDT信号处理芯片AD598的工作原理,重点分析了使用AD598芯片设计的应用电路的调试过程。在传统位移传感器上使用AD598芯片,提高了测量精度且功耗小,工作可靠性高,在测试过程中电压和位移基本上符合比例关系。     

四阶椭圆变分不等式的微分形式及有限元法的收敛阶

本文通过引入L~2(Ω)→H~1。(Ω)∩ΩH~2(Ω)的连续可逆线性算子A,讨论了固支和简支障碍曲率约问题和平均束问题的变分形式和微分形式,证明了其等价性。然后利用等价的微分形式,讨论了固支障碍问题非协调Adini元逼近及固支和简支带平均曲率约束问题的混合有限元逼近的收敛阶,在只需解u∈H~3(Ω)的正则性条件下,得到其收敛阶为: