Numerical competence in young children and in children with mathematics learning disabilities

A longitudinal study was conducted on 82 children to investigate, firstly the numerical competence of young children and the predictive value of (pre)-numerical tests in kindergarten, and, secondly, whether children's knowledge of the numerical system and representation of the number size is related to their computation and logical knowledge and to their counting skills. In an additional cross-sectional study on 30 children with a clinical diagnosis of mathematical learning disability (MLD) of 8,5 years, age- and ability-matched with 2 × 30 children the same parameters of numerical competence were assessed. The longitudinal data showed individual differences in numerosity, as well as the relationship between a delay in arithmetics in grade l and problems on numerosity in kindergarten. In the cross-sectional results some evidence was found for the independence of numerical abilities in MLD-children. About 13% of them had still severe pre-numerical processing deficits (in number sequence production, cardinality skills and logical knowledge) in grade 3. About 67% had severe difficulties in executing calculation procedures and a lack of conceptual knowledge. A feature of 87% of the MLD-children was severe translation deficits, with a significantly worse knowledge of number words compared with the knowledge of Arab numerals. Finally a severe deficit in subitizing was found to be present in 33% of the MLD children. On a group level the processing deficits were linked to understanding numerosity, since the ability-matched younger children and the MLD-children had the same pre-numerical and numerical profile. Implications for the assessment of mathematical disabilities and the value of TEDI-MATH® as an instrument in this process are discussed.     

关于等厚干涉条纹数目的讨论

大学物理中,计算等厚干涉形成的条纹数目时,经常采用计算相邻两明(暗)纹的间隔数,然后条纹间隔数即等于条纹数。多年的教学实践表明采用上述方法计算明、暗条纹数,物理意义不很清晰,特别是学生不易掌握。文中提出了采用加强和减弱条件计算明、暗条纹数的方法,该方法意义明确,学生更易于接受。     

P_n、C_n和S_n的r(2)点染色

提出了图的r(2)点染色的概念,研究了路Pn、环Cn、星Sn的r(2)点染色问题,并得到了它们的r(2)点色数.     

支配数为2的图的最小特征值

主要考虑简单图,其特征值定义为它的邻接矩阵的特征值.在所有给定阶数且支配数为2的连通图中,完全刻画了最小特征值达到极小的图.     

A 10 Year Collaboration—Still Going Strong,Ulrich's and ISSN

Collaboration between Ulrich's and the National Serials Data Program began more than ten years ago. Today the names have changed but this partnership continues to benefit publishers, libraries, and vendors who provide access to electronic serials. Many challenges are presented by differences in the metadata collected. A commitment to common goals and sharing metadata has made the partnership work.     

智能网号码携带业务的研究

从上个世纪末到本世纪初，智能网技术得到了迅猛发展和广泛应用，它不但给成千上万的用户带来方便，而且为运营商带来了无限商机。本文以如何使用智能网技术实现号码携带业务为例，系统地介绍了智能网技术运用方法。     

关于联图P_n∨C_n的邻点可区别的均匀全染色

一个图G的全染色被称为邻点可区别的如果满足图G中任意两个相邻点所关联的元素所染的色的集合不同.一个图的邻点可区别的全染色被称为均匀的如果满足任意两色所染元素的数目之差的绝对值不超过1.本文研究了联图P_n∨C_n的邻点可区别的均匀全染色并证明它满足邻点可区别的均匀全染色猜想.     

漳州明代状元林震的《墓志铭》与《行状》

有关明朝状元林震的生平资料,过去所知甚少。最近从福建省南靖县船场镇星光村鼎寮社林春荣先生保存的《泰昌堂西河弘仕祖派族谱》中,发现了《林震墓志铭》和《行状》。林震生于洪武二十一年(1388年)七月一日,卒于正统十三年(1448年)六月十一日,1439年致仕。     

二维联系数及其应用

从系统工程可靠性出发,我们用一种新型的系统分析理论——集对分析,提出集对分析的二维联系数以及其性质,并利用二维联系数的性质探讨系统工程中串联与并联的可靠度的计算公式,从而比较简单方便地解决了系统工程中关于串联与并联的可靠性的问题．