Strategic aspects of children’s numerosity judgement

A previous study (Luwel, Verschaffel, Onghena, & De Corte, 2000) revealed that 2^nd and 6^th graders use at least 3 different kinds of strategies for determining different numerosities of blocks presented in square grids: (a) an addition strategy by means of which (groups of) blocks are counted (and added), (b) a subtraction strategy in which the number of empty squares is subtracted from the total number of blocks in the grid (i.e. the anchor), and (c) an estimation strategy, whereby the number of blocks is determined in a quick but imprecise way. Although 6^th as well as 2^nd graders used the clever subtraction strategy, the majority of 2^nd graders had serious trouble with the correct determination of the anchor, resulting in huge numerosity judgement errors. Since this finding seriously complicated the testing of a number of hypotheses in that study, we replicated the above study but presented the children information about the grid size. This manipulation led to a substantial increase in the proportion of appropriate subtraction strategy users and made it possible to investigate the effect of several subject and task variables on the frequency, accuracy, and adaptiveness with which the different strategies were applied. Results are discussed in terms of the conceptual framework of Lemaire and Siegler (1995) regarding strategic change.     

LM317集成稳压电路在LED显示电路中的应用

三端可调型正电压输出稳压电路LM317在LED显示电路中可以替代LED显示器的限流电阻．这种接法在驱动合适数目的LED时．具有独特的优点．     

在加强本科院校建设中如何体现自己的办学特色

高等院校要实现可持续发展，必须树立“正确定位，办出特色”的办学理念，必须树立人才培养质量是生命线的办学思想，必须加强科学研究能力，走科研兴校之路，必须营造良好的校园氛围。     

青年大学生素质塑造探析

青年学生是民族的未来，应将如何学习做人放在首位，加强科学文化知识的学习，积极参加各项文化体育活动，踊跃投身社会实践，时刻准备着为社会主义现代化建设做出贡献。     

Hybrid heuristic and mathematical programming in oil pipelines networks： Use of immigrants

We solve the problem of petroleum products distribution through oil pipelines networks. This problem is modelled and solved using two techniques: A heuristic method like a multiobjective evolutionary algorithm and Mathematical Programming. In the multiobjective evolutionary algorithm, several objective functions are defined to express the goals of the solutions as well as the preferences among them. Some constraints are included as hard objective functions and some are evaluated through a …     

Effects of kindergarten retention for at-risk children’s psychosocial development

Kindergarten retention is a popular practice for children who are considered unready for primary school. However, past research has not yet succeeded to find consistent, strong empirical evidence supporting the practice. In the current study, kindergarten repeaters’ development in nine psychosocial domains is compared with that of equally at risk but (1) continuously promoted age-mates and (2) promoted age-mates who repeated first grade instead. Analysing data from a large-scale longitudinal study using propensity score matching and multilevel modelling, the findings reveal no harm of kindergarten retention for at-risk children’s long term psychosocial development. Rather, we find that, relative to equally at-risk but continuously promoted children, kindergarten repeaters benefit from retention with respect to higher levels of well-being, and peer relations, and lower levels of hyperactivity, aggression and asocial behaviour. Compared to similar children who were promoted but who were retained in first grade instead, kindergarten repeaters are found to benefit more from retention with respect to higher levels of well-being, self-confidence, attitude to work and independent behaviour, and lower levels of hyperactivity.     

谢桥煤矿综采放顶煤开采的实践与认识

谢桥矿在集团公司率先在C13-1煤层突破“三软”高瓦斯的禁区,实验综采放顶煤开采方法,成功开采了12个综放面,生产原煤1 524万t,其间在2001年建成集团公司第一个150万t综采队,产量,效率,效益,安全等方面取得了不断提高的效果,为我矿及集团公司开采C13-1煤层开辟了一条新的途径;主要是在概述本矿应用综采放顶煤技术的基础上,重点总结、分析了八年来综采放顶煤的技术成果,提出了综采放顶煤技术需要解决的一些问题及建议,为进一步优化综采放顶煤技术提供一定的依据.     

汽轮机冷凝器污垢自转塑料纽带连续清洗节能技术

本介绍了作对水垢-汽轮机冷凝器真空度影响状况的调查及其水垢引起的经济损失估计，叙述了自转塑料纽带的连续清洗和传热强化原理，试验表明自转塑料扭带的连续清洗能力能够满足冷凝器污垢清洗的要求，并且兼有幅度为9％-15％的传热强化作用，长时间的考核试验运行没有发现扭带对钢管壁的磨损问题，计算分析说明连续清洗纽带对提高机组真空度、出力和增产增效的作用显。     

Transition from high school to university: a person-centered approach to academic achievement

Although a vast body of studies regarding the variables related to students’ achievement exists, only a handful has investigated how these variables combine and interact together. Such an investigation might make it possible to more accurately illustrate the heterogeneity of students enrolling in university and assess the impact of this diversity on academic achievement. The current study focused on the person-centered approach and investigated the possibility of determining significant subgroups of freshmen in the very first week of the academic year in the Belgian educational context. Using k-mean clustering, 2178 freshmen were classified according to their past performance, socioeconomic status, study choice process, and academic self-efficacy beliefs at the beginning of the first year at university. Analyses of variance were also conducted to analyze the relationship between these student clusters and academic achievement outcomes. Six distinct profiles of students were identified representing different combinations of achievement predictors. Results revealed different odds of success among these profiles. The implications of our approach to the understanding of the heterogeneity of freshmen and the first-year achievement process are discussed.     

论新历史主义的理论旨趣及其文化影响

新历史主义之"新",在于它是一种将历史文本化,用文化阐释的方式解读历史的理论,它关注的重心不再是由实在事件构成的"历史",而是由话语符号构成的文本和贯穿于文本之中的"文化",因而对其更为准确的描述应是"历史文化主义"。相对于原来带有实证主义色彩的历史主义而言,它将一种对于文学而言的外在性历史视角,转化为文化场域内历史文本与文学文本的互文关系。这种研究方法一方面通过将历史文本化,历史首先被视为一种文本的建构而非客观的存在,动摇了历史叙述中那种根深蒂固的语言透明性,使外在性的历史以"文本—文化"的方式转化成了内在性的历史;另一方面通过在文学文本和历史文本之间建立起互文关系,将形式方法扩展到了文化领域,将原有的文学文本之间的互文转化成了一种文学与历史之间的"跨文体互文",新历史主义在一定意义上打破了形式主义、结构主义等研究方法的纯内在性。这种泛文本化的思想方法为文化研究开辟了道路,形成了一种文化诗学、历史诗学。但这种文本化的方式依然存在着两方面的困境:其一是使文学理论研究中的二元对立的否定性结构更为显著;其二是使"历史"被抽空了丰富性的内核,成了空洞的概念。新历史主义的这种困境也是文学理论尝试以二元对立的共时性结构来批判实证主义、经验主义,重建一种文本自律性的理论体系这一尝试的最终困境。新历史主义使文学理论走到了"文学之外",却没能使文学研究以一种新的方式真正地走到"文化之外"、"文本之外",新历史主义者依然没能走出杰姆逊意义上的"语言的牢笼",将一切泛文本化实际上否定了文学有任何超越文本之外的现实价值。