The theory of recombination of gaseous ions     

Leonard B. Loeb  Lauriston C. Marshall 《Journal of The Franklin Institute》1929,208(3):371-388

The bearing of the recent results of Marshall on the theory of recombination of gaseous ions is discussed. It is shown, by solution of the Brownian movement equation for two ions of opposite sign, in a gas, that the average relative displacement in a time π is little influenced by the attractive forces, except for distances of the order of magnitude of 10^?5 cm. or less, at ordinary temperatures. This conclusion, that in general the motion of the ions relative to each other is largely one of random diffusion, is in good agreement with the interpretation forced by Marshall's study of the variation of the coefficient of recombination α with time and concentration of ions. This also indicates that the theoretical approach of Langevin to the solution of the recombination problem is untenable, while that of Thomson is justified. The theory, of Thomson is discussed and, is compared with observation. It appears to fit qualitatively as accurately as the facts are known.It is then shown how the success of any theoretical treatment is limited due to our ignorance of the nature of the mass of the ion, a condition which, however, enables us to understand the very small range of variation of α among the different gases.  相似文献   

Economic considerations influencing instructional technology. A brief commentary and decision rules     

W. Patrick Leonard 《Performance Improvement》1983,22(7):26-27

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The more things change the more things change     

Leonard Finkelman 《Metascience》2015,24(3):409-412

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Space and Enclosure in Cooper and Peckinpah: Regeneration in the Open Spaces     

Leonard Engel 《Journal of American culture (Malden, Mass. : 2003)》1991,14(2):86-94

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Teaching machine technology: The state of the art     

Leonard C. Silvern 《Educational technology research and development : ETR & D》1962,10(3):204-217

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Selecting the retail price: Some comments on an unavoidable decision     

Leonard Shatzkin 《Publishing Research Quarterly》1997,13(3):103-109

This article explores the judgments employed in the getting of productive retail prices.  相似文献   

Learning from our own lessons: pre-service teachers’ narratives of teaching as an experiment     

Megan H. Wickstrom  Stephanie Wilm  Emily Mills  Alexis Johnson  Nicole Leonard  Raegan Larberg 《Educational Action Research》2018,26(1):42-58

Pre-service teachers need to develop habits of mind that allow them to grow as new teachers. This article describes an elementary mathematics methods course in which teaching as an experiment was used a framework for pre-service teachers to participate in action research by developing learning goals, observing and analyzing student thinking, hypothesizing and enacting teaching strategies, and reflecting on the effectiveness of a lesson. Through analysis of reflections and lesson plans, the article explores three groups of pre-service teachers’ reflections on teaching as well as their confidence across the semester. By treating lessons as experiments, the pre-service teachers were able to develop appropriate teaching responses over time as well as gain confidence in their abilities.  相似文献   

An experimental test of an extended discretion laboratory approach for university general biology     

William H. Leonard 《科学教学研究杂志》1989,26(1):79-91

This was an experiment to test the extended discretion laboratory approach (ED) versus a guided-inquiry (GI) approach for teaching biology in a university setting. It had previously been found productive in a high-school setting. The approach provides considerably less specific procedure for the students to follow than did a guided-inquiry approach and required relatively high independence. Four hundred sixty-nine students taking university introductory biology were randomly assigned to using either the ED learning approach or one characterized as guided inquiry for one semester. Three measures were taken to verify that instructional treatments followed the two approaches. All indicated qualitative and quantitative differences between ED and GI approaches in the direction predicted by the operational definitions. The criterion variables were (1) student scores on a multiple-choice laboratory exam, (2) student scores on laboratory reports, and (3) student scores on six laboratory quizzes given during the semester. The only criterion variable which showed significant differences between groups (laboratory-report scores) also showed significant group-by-instructor interaction. The hypothesis of no difference therefore stood unrejected for all criterion variables. Since the ED approach appears to produce equivalent learning gains in understanding of biology laboratory concepts compared to a guided-inquiry approach, this approach should still be considered for laboratory teaching, because it purports to train for discretionary use of resources during instruction in addition to the conventional development of laboratory concepts.  相似文献   

The Development of Affiliative and Agonistic Social Patterns in Differentially Reared Monkeys   总被引：1，自引：0，他引：1  

Michael W. Andrews  Leonard A. Rosenblum 《Child development》1994,65(5):1398-1404

Bonnet macaques that had been reared from 3 to 6 months of age in experimental environments that appeared to adversely affect their ability to separate from mother to explore a novel physical environment in dyadic assessments shortly after the rearing experience were tested during late adolescence, an average of 2.5 years later, under conditions of increasing unfamiliarity and complexity of the social milieu. 6 monkeys, the low-foraging-demand (LFD) group, were reared by mothers having constant easy access to food during the experimental rearing period. Another 6 monkeys, the variable-foraging-demand (VFD) group, were reared by mothers having a foraging task that varied between easy and difficult in 2-week blocks during the experimental rearing period. Although no treatment group differences were evident during the initial rearing period, during subsequent social challenges VFD monkeys exhibited a diminished capacity for affiliative social engagement relative to LFD monkeys and were socially subordinate to LFD monkeys.  相似文献   

THE CONCEPT OF FUNDAMENTAL EDUCATIONAL CHANGE     

Leonard J. Waks 《Educational theory》2007,57(3):277-295

A bstract .  In this essay, Leonard Waks contributes to a reconceptualization of "fundamental educational change." By distinguishing sharply between educational change at the organizational and the institutional levels, Waks shows that the mechanisms of change at these two levels are entirely different. He then establishes, by means of a conceptual argument, that fundamental educational change takes place not at the organizational, but rather at the institutional level. Along the way Waks takes Larry Cuban's influential conceptual framework regarding educational change as both a starting point and target of appraisal.  相似文献