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71.
72.
A binary approach to data storage and retrieval is introduced. It views the data base as a two-dimensional matrix that relates entities to all possible values the attributes of these entities may take. As such, it provides a unified solution to the two conflicting types of data base transactions—operational and managerial. An analytical investigation of the feasibility of binary storage and a compression method for reducing meaningless areas of the matrix are presented. Storage efficiencies of binary and conventional inverted file methods are compared and evaluated. An analysis of retrieval considerations associated with the binary matrix is given, particularly the issue of going from high to low orders of compression. Results of these analyses indicate that the binary data base's efficiency increases with increases in query complexity. Future research directions are sited and discussed.  相似文献   
73.
Dilute, intragastric infusions of carbohydrate stimulate saccharin intake. To determine whether this effect is due to an associative process, a yoked control was employed. One group of rats was trained in the conventional fashion: they received carbohydrate (maltodextrin) infusions whenever they drank saccharin. Whenever these rats were infused with carbohydrate, yoked rats were infused with the same amount of carbohydrate. In an experiment in which saccharin was available continuously, carbohydrate infusions stimulated saccharin intake in conventionally trained rats but not in yoked rats. In a subsequent experiment, in which rats were offered saccharin for only 2.5 h/day, carbohydrate infusions stimulated intake in conventionally trained and in yoked rats. However, when these rats were switched to continuous saccharin availability, saccharin intake declined in yoked rats but remained elevated in conventionally trained rats. Thus, carbohydrate infusions stimulate saccharin intake via an associative process.  相似文献   
74.
The purpose of this study was to identify the extent to which intrinsic student factors such as cognitive learning style, learning strategies, motivation and statistics anxiety, as well as certain demographic factors, predict performance on a research design and analysis course (RDAIIA) in the Department of Psychology at the University of the Witwatersrand, South Africa, with a view to developing future interventions for improving student performance. Using a sample of eighty students, it was established that the factors most predictive of RDA performance were secondary school performance (p < 0.0001) and age (p = 0.0106). Excluding demographic factors, self-efficacy (p < 0.0001), help-seeking (p = 0.0531) and a reflective learning style (p = 0.0071) were also found to be predictive. Performance also differed between students who had completed Mathematics on the higher grade in secondary school and those who had completed standard grade (p = 0.016). These findings present both possible directions and substantial challenges for future performance-intervention strategies.  相似文献   
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