Reconceptualising educational assessment in South Africa — testing times for teachers

This paper explores some of the problems arising when Continuous Assessment (CA) is grafted onto established pedagogic practices. It focuses on three issues: teachers' restricted understandings of assessment, teachers' emphasis on criteria that demonstrate concern with social control, and some of the problems connected with peer assessment. Two vignettes derived from fieldwork associated with a project to improve the quality of primary education are used to raise the issues. We argue that the development of desired practices is hampered above all by tacit values in tension with those underpinning the new curriculum. These values, together with the complexity of curriculum design, create serious problems of manageability and interpretation, which can only be addressed through detailed interactive in-service training, aimed at reconceptualising teachers' notions of assessment.     

Seeking Nettle Textiles – Utilizing a Combination of Microscopic Methods for Fibre Identification

Bast fibres have been commonly used as a textile material in Northern Europe since Neolithic times. However, the process of identifying the different species has been problematic, and many important questions related to their cultural history are still unanswered. For example, a modified Herzog test and the presence of calcium oxalate crystals have both been used in identification. In order to generate more reliable results, further research and advancement in multi-methodological methods is required. This paper introduces a combination of methods which can be used to identify and distinguish flax (Linum usitatissimum), hemp (Cannabis sativa), and stinging nettle (Urtica dioica). The research material consisted of reference fibres and 25 fibre samples obtained from 12 textiles assumed to be made of nettle. The textiles were from the Finno-Ugric and Historical Collections of The National Museum of Finland. The fibre samples were studied by observing the surface characteristics and cross sections with transmitted light microscopy, and by using a modified Herzog test with polarized light, in order to identify the distinguishable features in their morphological structures. The study showed that five out of 25 samples were cotton, 16 nettle, one flax, and one hemp. Findings from two samples were inconsistent. The results show that it is possible to distinguish common north European bast fibres from each other by using a combination of microscopic methods. Furthermore, by utilizing these combined methods, new and more reliable information could be obtained from historical ethnographic textiles, which creates new vistas for the interpretation of their cultural history.     

Volterra积分方程解的存在性

建立了Volterra积分方程存在三个非负解的一些标准，并给出了结论的具体运用．问题的证明中运用了LeggettWilliams不定点理论．     

Numerical method to determine mechanical parameters of engineering design in rock masses

INTRODUCTION The historical development of research in rockmechanics has yielded numerous useful and work-able theories. The Coulomb Criterion (1772) andMohr’s Hypothesis (1990) both provide easy andeffective methods for determining mechanical pa-rameters such as rock strength. R.E. Goodmanformulated the equation of mesh and non-meshjoints construction. Other researchers conductedexperiments on different types of rock masses withspecific, unique properties, to solve increasinglyc…     

New insights into brazilwood lake pigments manufacture through the use of historically accurate reconstructions

A multi-analytical approach for the study of brazilwood and its lake pigments was carried out based on historically accurate reconstructions. Recipes for brazilwood lakes from the fifteenth century technical text Livro de como se fazem as cores and the Winsor & Newton nineteenth century colourman's archive were reproduced and compared. Both primary sources allowed for the successful preparation of brazilwood lake pigments with colours that vary from light pink to dark red. The main steps and ingredients for the manufacture of these pigments were common in both sources, particularly the addition of Al³⁺ in the form of alum, and calcium carbonate (chalk). Reconstructions revealed that the latter acts as a pH buffer and filler, controlling the pH at which the lake pigment precipitates. The main difference between the two sources is that the nineteenth century recipes give the quantities for all ingredients, the precise temperatures and time, and achieved higher relative pigment yields (75% versus 45%). Full chemical characterisation of the reconstructions provided detailed information on the individual steps in the pigment manufacture and revealed that the presence of calcium sulphate dihydrate (gypsum) in the final pigment was a result of its formation in situ. Infrared, reflectance, and fluorescence spectroscopy proved to be essential and complementary techniques: while infrared was used to characterise additives and binders, reflectance and fluorescence data were fundamental for identifying the chromophore. The pigments and paints produced can now be used as standards for the identification and investigation of brazilwood lake pigments found in artworks.     

从词义角度谈现在进行时言外之意

英语时态形式与意义不一致的现象是广大英语学习者在英语应用中很容易产生错误的地方。时态的意义和用法并不能以时态形式笼统解释。现在进行时不表示"正在进行"的原因正是动词本身的词义所决定的。根据词义,动词有静态动词和动态动词之分,现在进行时除表示"现在正在进行"的行为动作以外,还包括表示"过去"、"将来"、"渐进"、"重复"、"临时"、"描述"等意义。     

爱因斯坦对布朗运动的解释与现代统计动力学

回顾爱因斯坦对布朗运动的统计解释.介绍用连续时间随机行走模型对布朗运动粒子行为进行描述,与爱因斯坦的结论进行了比较而得出结论:由连续时间随机行走模型得出的结论比爱因斯坦的结论更具有一般性.     

VUHZ电磁液位监测系统在连铸机上的应用

VUHZ电磁液位传感器在世界各大钢厂占有非常重要的份额,性能稳定,使用简单便于维护。本文从电气硬件设定和PLC程序软件两个方面介绍VUHZ液位监测系统在结晶器液位控制方面正确使用。     

放射性物位计在连续重整装置的应用

催化剂再生系统是连续重整装置反再部分的核心环节。在催化剂再生和循环的过程中需要准确检测催化剂的物位,为控制系统提供可靠参数。放射性物位计就是一种能准确检测设备中催化剂物位的仪表。本文介绍了放射性物位计的工作原理、配置方法和防护事项。同时,结合国产连续重整工艺,介绍了放射性物位计在连续重整中的设置和标定。