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991.
Dr Jim Woolnough 《Research in Science Education》2000,30(3):259-267
This paper describes a laboratory-based program in physics designed to help students build effective links between the mathematical
equations used to solve problems in mechanics and the real world of moving objects. Through the analysis of straight line
graphs derived from their own data students have been able to achieve a considerable development towards a concept of slope,
or gradient, and how it relates to the concept of proportionality, but they continue to demonstrate a great resistance to
applying their mathematical knowledge to physics. A model designed to help us apply current research ideas to this problem
is described. The work described in this paper was carried out at Dickson College, a government senior secondary college (Years
11 and 12) in the Australian Capital Territory, where the author taught physics and biology. 相似文献
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This paper presents a longitudinal study, from kindergarten to secondgrade, which aims to examine the relationship between morphologicalanalysis, phonological analysis and learning to read. Three phonologicalawareness tasks, five derivational and four inflectional subtests wereadministered to fifty children at each of the three levels. Evolution ofperformance was analyzed through the three years. Data showed that withthe exception of two subtests, performance increased from kindergarten tofirst grade and from first grade to second grade, without reaching ceilingperformance in second grade, at least for morphological subtests. Linksbetween morphological and phonological analyses were very strong: inparticular, syllable segmentation was highly correlated with themorphological subtests in kindergarten while phonemic segmentation wascorrelated with morphological subtests in first and second grade. Therewere also strong links between morphological analysis and reading.Regression analyses showed that while phonological awarenessexplained a major part of variance in first grade, both phonologicaland morphological scores explained significant part of variance of bothdecoding and comprehension reading scores in second grade. Thus, thislongitudinal study contributes to the evidence of a link between bothphonological and morphological analysis and learning to read French. 相似文献
995.
The aims of this study were to investigate the energy build-up and dissipation mechanisms associated with using an arm swing in submaximal and maximal vertical jumping and to establish the energy benefit of this arm swing. Twenty adult males were asked to perform a series of submaximal and maximal vertical jumps while using an arm swing. Force, motion and electromyographic data were recorded during each performance and used to compute a range of kinematic and kinetic variables, including ankle, knee, hip, shoulder and elbow joint powers and work done. It was found that the energy benefit of using an arm swing appears to be closely related to the maximum kinetic energy of the arms during their downswing, and increases as jump height increases. As jump height increases, energy in the arms is built up by a greater range of motion at the shoulder and greater effort of the shoulder and elbow muscles but, as jump height approaches maximum, these sources are supplemented by energy supplied by the trunk due to its earlier extension in the movement. The kinetic energy developed by the arms is used to increase their potential energy at take-off but also to store and return energy from the lower limbs and to "pull" on the rest of the body. These latter two mechanisms become more important as jump height increases with the pull being the more important of the two. We conclude that an arm swing contributes to jump performance in submaximal as well as maximal jumping but the energy generation and dissipation sources change as performance approaches maximum. 相似文献
996.
Gérald Séguin 《Journal of The Franklin Institute》1980,309(3):179-189
A sequence of metrics {DN} is said to be additive and matched to a discrete memoryless channel (DMC) if DN is the sum on its coordinates of N single letter metrics and if the maximum likelihood decoder for sequences of length N is a minimum DN-distance decoder. Necessary and sufficient conditions on the transition probabilities of a DMC for the existence of a sequence of additive metrics matched to it are given. In the case of the binary channel these are shown to be equivalent to the channel being symmetric. Explicit transition probabilities are given for a large class of ternary DMCs with an associated sequence of additive matched metrics. The problem solved here may be considered a generalization of the problem of finding the DMCs matched to the Lee metric solved by Chiang and Wolf in 1971 (2). 相似文献
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