Does class-size reduction close the achievement gap? Evidence from TIMSS 2011

Policies about reducing class size have been implemented in the US and Europe in the past decades. Only a few studies have discussed the effects of class size at different levels of student achievement, and their findings have been mixed. We employ quantile regression analysis, coupled with instrumental variables, to examine the causal effects of class size on 4th-grade mathematics achievement at various quantiles. We use data from 14 European countries from the 2011 sample of the Trends in International Mathematics and Science Study (TIMSS). Overall, there are no systematic patterns of class-size effects across quantiles. Class-size effects are generally non-significant and uniform at different achievement levels, which suggests that in most European countries class-size reduction does not have an impact on student achievement and does not close the achievement gap. However, combined estimates across countries indicate that high achievers may benefit more from class-size reduction.     

Very long-term retention of the control of variables strategy following a brief intervention

Middle school students (n = 354) were tested for their understanding of the control of variables strategy (CVS) 2.5 years after participating in a study comparing three different interventions for teaching CVS. The key finding was that the pattern of effects observed in the 4^th grade continued to be observed in the 6^th grade. This was because (a) students who had mastered CVS in the 4^th grade were likely to continue to perform at mastery levels in the 6^th grade whereas (b) the learning of students who had not mastered CVS in 4^th grade was independent of the teaching intervention they had received in the 4^th-grade study. These findings demonstrate that a brief intervention of direct instruction in CVS can produce long-lasting learning of the principle of controlling variables.     

中外区域经济政策的比较及其对西部大开发的启示

中国的区域经济政策与其他国家实施的区域经济政策相比,在政策目标、政策的制定与实施和政策内容方面有很大差异。西方发达国家的区域经济政策在长期的实践中已具有了一定的规律。本文旨在通过对西欧、美国、日本及一些亚洲国家与中国在区域经济政策上的比较,从中总结出对我国西部大开发中制定和实施区域经济政策的启示。     

渔船备件费用的灰色预测模型及应用

备件是渔船的必需品,渔船备件费用预测是渔业公司管理的难题之一。本文基于灰色理论对渔船备件费用进行了预测,计算结果表明,灰色预测模型算法简单,精度较高,是一种较为理想的预测方法。     

试论考研大学生的心理顾虑及调试策略

随着我国高等教育的发展和就业形势的日益严峻,越来越多的大学生加入了考研大军。但是,面对考研,很多学生难以下定决心,有的虽然决定考研,也存在诸多心理顾虑。本文对考研大学生存在的心理顾虑及其产生原因进行了剖析,并提出了积极的调试策略,以帮助大学生走出顾虑,坚定考研信心。     

基于遥感的渭河关中地区生态景观格局变化研究

基于遥感（RS）和地理信息系统（GIS）技术,以1978年-2007年的LandsatMSS／TM／ETM影像为数据源,综合运用数理统计和景观生态学理论和方法,对渭河流域关中地区1978年-2007年生态景观格局动态变化进行了研究。结果表明：渭河流域关中地区各景观类型都发生了不同程度的消长变化,耕地斑块面积减少,但分离度和破碎度增加;草地和林地斑决面积增加,破碎度和分离度减小;居民工矿建设用地面积显著增加;未利用土地斑块面积有所减少。从景观格局变化来看,渭河流域关中地区景观斑块分布趋于破碎化,破碎度指数ZA0．9127下降为0．8755;景观多样性指数和景观均匀度指数均在20世纪90年代有所增加,分别增长了2．72％和2．71％,之后锐减,2000年达到最低后逐渐有所回升;景观优势度也在20世纪90年代有所增加,后逐渐减小。说明近期研究区生态景观的异质性有所改进,生态景观格局处于快速调整并趋于稳定发展阶段。     

Company related variables and their impact on the NPD outcome in the context of international markets in Finnish high-technology companies

While much research has been directed at the variables critical to successful R&D of new products on the one hand and high-technology products on the other, much less work has been directed at those factors crucial to the success of these products when the firm enters the international marketplace. This study surveys Finnish high-technology firms and variables related to the properties of the company and their association with successful versus unsuccessful attempts to enter the international marketplace. Relationship between firm characteristics – type of industry, size of the company, background of key personnel, export intensity and experience in product launches – and success/failure in the product launches is investigated. The generalizability of the findings is also discussed.     

浅谈如何抓好施工现场质量管理的重要环节

一个优质的建设工程是通过施工前期的质量管理和施工过程的质量管理来实现的,而现场质量管理是施工过程中质量管理的重要组成部分。因此,切实抓好施工现场质量管理是创造优良工程的关键。在施工现场质量管理中,样板管理、施工过程质量监控管理、质量验评管理是现场质量管理的重要环节,实践证明重视和抓好这些环节,能促使工程质量收到较好的效果。     

日语叠词的构词及词性琐谈

叠词在现代日语中数量多且构词及词性复杂,并因是具有栩栩如生地表达语义效果及意境的语言现象,而被广泛应用着。所以,为能准确、恰当、自然而巧妙地使用叠词,就必须了解叠词的构词及词性。