Getting remedial mathematics students to prefer homework with 20% and 40% more problems: An investigation of the strength of the interspersing procedure

High school students in remedial mathematics classes were exposed to three pairs of mathematics computation assignments. Three of the assignments served as control assignments and contained 15 target problems (i.e., three‐digit by two‐digit multiplication problems). Students were also exposed to three paired experimental assignments that contained either 15 (0% more), 18 (20% more), or 21 (40% more) equivalent target problems. Each experimental assignment was also lengthened by interspersing additional one‐digit by one‐digit problems following every third target problem. After exposure to each pair of assignments, students reported which of the two assignments (control or experimental) would require the most time and effort to finish, which was most difficult, and which assignment they would prefer to do for homework. Across all three assignment pairs, significantly more students rated the experimental assignment more favorably for time, effort, and difficulty and chose the experimental assignment for homework. These results extend previous research on interspersing additional brief tasks by showing that this procedure has sufficient strength to get students to prefer homework assignments with 20% and 40% more target problems. © 2000 John Wiley & Sons, Inc.     

Methodological considerations for the 3D measurement of the X-factor and lower trunk movement in golf

It is believed that increasing the X-factor (movement of the shoulders relative to the hips) during the golf swing can increase ball velocity at impact. Increasing the X-factor may also increase the risk of low back pain. The aim of this study was to provide recommendations for the three-dimensional (3D) measurement of the X-factor and lower trunk movement during the golf swing. This three-part validation study involved; (1) developing and validating models and related algorithms (2) comparing 3D data obtained during static positions representative of the golf swing to visual estimates and (3) comparing 3D data obtained during dynamic golf swings to images gained from high-speed video. Of particular interest were issues related to sequence dependency. After models and algorithms were validated, results from parts two and three of the study supported the conclusion that a lateral bending/flexion-extension/axial rotation (ZYX) order of rotation was deemed to be the most suitable Cardanic sequence to use in the assessment of the X-factor and lower trunk movement in the golf swing. The findings of this study have relevance for further research examining the X-factor its relationship to club head speed and lower trunk movement and low back pain in golf.     

Medical Fellows Tell Stories of Application: A Grounded Theory on the Dynamics of Transfer

In this exploratory study, researchers collected and analyzed physician's stories of how they had applied what they had learned from a medical fellowship. We describe and explain the patterns shown in five cases of application. Based on these cases we form a theory of transfer for autonomous professionals learning an open skill. The findings support the claim that transfer is a dynamic process. We view transfer as part of a continuous learning and motivational process extending to a learner's past and projecting into a learner's future. The theory, in brief, is that professionally oriented learners follow an iterative constructive pattern of application when applying knowledge: learners perceive the usefulness of an idea, become ready to use the notion, make the application, and learn from its implementation. We also briefly describe practical and theoretical implications of the theory.     

Environmental Education in Primary Education: status and trends in southern and eastern Africa

This study presents the results of an international comparative study (based on secondary analysis techniques) into the status of environmental education (EE) in primary education in 10 southern and eastern African countries. The study concludes that the current provisions for EE in primary education in the countries sampled are insufficient for the comprehensive development of national programmes. The major barriers to the further development ofEE include inadequate provisions for EE in education policy, deficiencies in teacher training in EE and a lack of instructional materials. The study recommends that the most important step towards improving the status of EE in primary education in the region is the inclusion of EE in education policy, combined with the development of a mechanism that would facilitate policy implementation.     

Trinucleotide repeats and neuropsychiatric disorders

Expansions of trinucleotide repeats at the level of genomic DNA are increasingly recognized as a cause of a number of neuropsychiatric disorders. Triplet repeat disorders are commonly classified into two groups, those with moderate CAG expansions that result in a polyglutamine stretch in the gene products and those with very long expansions, usually non-CAG, that are not translated. The triplet repeat intergeneration and intra-generational instability, and genetic anticipation characterize disorders. Most of the diseases caused by expanded CAG repeat share common features, which include neurodegeneration, a dominant pattern of inheritance and widespread expression of the gene products with neuronal loss restricted to distinct subset of neurons. Neurodegenerative changes associated of CAG expansion disorders is explained in terms of intra and extra cellular aggregation of mutant gene products, the insoluble nature of the protein(s) being attributed to the presence of polyglutamine stretches, hence their neurotoxic effects. methods based on poymerase chain reaction have become handy in the diagnosis of these genetic disorders. Progress in transgenic animal models for these disorders will be critical for understanding the progress of these disorders and for testing new therapeutic strategies.     

Characteristics of character usage in Chinese Web searching

The use of non-English Web search engines has been prevalent. Given the popularity of Chinese Web searching and the unique characteristics of Chinese language, it is imperative to conduct studies with focuses on the analysis of Chinese Web search queries. In this paper, we report our research on the character usage of Chinese search logs from a Web search engine in Hong Kong. By examining the distribution of search query terms, we found that users tended to use more diversified terms and that the usage of characters in search queries was quite different from the character usage of general online information in Chinese. After studying the Zipf distribution of n-grams with different values of n, we found that the curve of unigram is the most curved one of all while the bigram curve follows the Zipf distribution best, and that the curves of n-grams with larger n (n = 3–6) had similar structures with β-values in the range of 0.66–0.86. The distribution of combined n-grams was also studied. All the analyses are performed on the data both before and after the removal of function terms and incomplete terms and similar findings are revealed. We believe the findings from this study have provided some insights into further research in non-English Web searching and will assist in the design of more effective Chinese Web search engines.     

Enhancing classroom management through proactive rules and procedures

This article presents an overview of classroom rule establishment and implementation within a proactive management strategy. Characteristics of classroom rules such as wording and means of presentation are included, and the intended nature and function of rules is discussed. It was concluded that rules do not work in isolation and therefore should be used in conjunction with an overall classroom management plan. Suggesitions for future research and practice are provided.     

析出硬化粉末冶金不锈钢

高硬度不锈钢的使用需求在快速增长.尽管析出硬化不锈钢具有高强度,但在粉末冶金(PM)中使用的并不多.可通过加入在时效过程形成金属问沉淀的成份如铜、铌对这些合金进行强化.析出硬化级不锈钢的耐腐蚀性能可与铬镍级(300系列)相媲美.本文提出了两种析出硬化不锈钢粉末的物理性质和微观结构:17-4PH,一种高铬马氏体析出硬化不锈钢,优化条件后应用于粉末冶金中;另一种是在析出反应中使用铜的新型低铬(12w/o)合金.这种新型合金(410LCu)被视为满足高强度和中等耐腐蚀性的要求的低成本选择.     

Electrokinetic focusing and filtration of cells in a serpentine microchannel

Focusing cells into a single stream is usually a necessary step prior to counting and separating them in microfluidic devices such as flow cytometers and cell sorters. This work presents a sheathless electrokinetic focusing of yeast cells in a planar serpentine microchannel using dc-biased ac electric fields. The concurrent pumping and focusing of yeast cells arise from the dc electrokinetic transport and the turn-induced ac∕dc dielectrophoretic motion, respectively. The effects of electric field (including ac to dc field ratio and ac field frequency) and concentration (including buffer concentration and cell concentration) on the cell focusing performance were studied experimentally and numerically. A continuous electrokinetic filtration of E. coli cells from yeast cells was also demonstrated via their differential electrokinetic focusing in a serpentine microchannel.