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71.
72.
Dynamic retinoscopy has suggested that near vision may be more acute than far vision during early infancy. To test this, acuity thresholds were determined by presenting square wave gratings in a preference paradigm to 1- and 2-month-old human infants at 4 viewing distances. Gratings were paired with unpatterned fields; direction of first fixation was the dependent measure. Infants exhibited the same acuity at each of the distances at which gratings were presented. The results were interpreted as compatible with the fact that considerable optical defocusing does not seriously affect a visual system, such as the infant's, that is sensitive only to low spatial frequencies. 相似文献
73.
W. Frank Hull IV Walter H. Lemke Jr. 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1978,24(1):53-64
While off-campus educational programs grow in number and in importance in American higher education, little systematic research has been conducted concerning their effectiveness and intellectual and developmental impact. The project described here compared students in three categories: those studying abroad; those studying off-campus in this country; and those who remained on their home campus. The implications of the findings of the research suggest that a rethinking of existing programs is appropriate, if off-campus educational programs are to realize their full potential. The authors offer concrete suggestions toward restructuring these programs.
Zusammenfassung Obwohl Bildungsprogramme ausserhalb der Universität in der amerikanischen Hochschulbildung an Anzahl und Bedeutung zunehmen, wurde deren Fruchtbarkeit und geistige und entwicklungsmässige Auswirkung kaum systematisch untersucht. Das hier geschilderte Projekt vergleicht Studenten dreier Kategorien: im Ausland studierende, im Lande ausserhalb der Universität studierende und solche, die in ihrem heimischen Universitätsbetrieb geblieben sind. Die Ergebnisse der Untersuchung legen die Folgerung nahe, es sei angebracht, bei eingeführten Programmen zu überdenken, ob die Bildungsprogramme ausserhalb der Universität ihre Möglichkeiten voll ausschöpfen sollen. Die Verfasser machen konkrete Vorschläge für eine Neugestaltung dieser Programme.
Résumé Tandis que l'importance et le nombre des programmes d'éducation en dehors des universités s'accroît dans l'enseignement supérieur aux Etats-Unis, peu de recherche systématique a été effetué en ce qui concerne leur efficacité et leur impact intellectuel et de développement. Le projet décrit ici a comparé des étudiants de trois catégories: ceux qui étudient à l'étranger, ceux qui étudient hors des universités à l'intérieur du pays et ceux qui sont restés dans leurs universités d'origine. Les implications des conclusions de la recherche suggèrent qu'il convient de repenser les programmes existants, si les programmes d'éducation hors des universités doivent réaliser tout leur potentiel. Les auteurs présentent des suggestions concrètes quant à la restructuration de ces programmes.相似文献
74.
75.
76.
It is often desirable to represent carrier distribution systems by networks so that analysis can be made to predict the behavior of these systems. Modeling of two canonical carrier distribution systems, the star-shaped system and the parallel-wire system by networks was carried out in this paper. The representation is given in terms of lumped parameters when the lengths of the carrier lines are short and it is given in terms of lumped and distributed parameters when the lengths of the carrier lines are long. 相似文献
77.
Robert H. Ennis 《Instructional Science》1974,3(3):285-298
Summary Definitions, I have suggested, have both a function and a form. The function pursued and the form used should depend on the situation and on the term being defined. In the situation described at the outset, Mr. Beta should probably have seen to it that a stipulation of some sort was given-just in order to get on with the task at hand. The stipulation might have been based upon a true reported definition-or it might not-depending on political considerations and the linguistic flexibility of the people concerned. Since no one involved could plausibly have been trying to embody a program in a definition of dough, a programmatic definition was not appropriate in that situation.Several different forms for a definition of dough might reasonably have been used, but in this case the old reliable classification form was probably best, because of its completeness, neatness, and brevity. Two reasonable alternatives are the equivalent-expression form and the range form. The synonym, example-nonexample, and operational forms were probably not appropriate.My main point is that there is not just one way to define. I hope that my delineation of some major possibilities and variations will help those who read this article to be flexible in handling problems of definition when they arise; and they arise more often than most people realize.An ealier draft of this article was presented at a colloquium at the University of Illinois in honor of Professor B. Othanel Smith at his retirement. 相似文献
78.
Walter Hahn Helmut Skowronek H. J. Butcher Hans-Martin Müller-Wolf J. C. Cairns Michael Angermaier Maureen Woodhall Ha Wun Sung Oskar Anweiler John A. Smyth Gilbert de Landsheere Gaby Venstermans Erika Voigt Anza Amen Lema David Wolsk Robert O. Berdahl 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1974,20(1):83-107
79.
In this paper, the stability equation method is applied to the analysis of nonlinear systems with characteristics equations having complex coefficients. Three types of systems are studied: those with unstable open-loop poles, unstable characteristics roots or an equal number of open-loop poles and zeros. 相似文献
80.