Polynomial Root Clustering

A sequence of tests on derived polynomials to be strictly Hurwitz polynomials is shown to be equivalent to a given (typically real) polynomial having all its zeros in an open sector, symmetric with respect to the real axis, in the left half-plane. The number of tests needed is at most 1 + ?(ln k)/(ln 3)?, where k is the integer associated with the central angle π/k of the sector. An extension of this result on the sector as a region of root clustering is given which shows that only a limited number of tests are needed to verify that the roots are clustered in a region composed as the intersection of a set of primative (sector-like) regions. The results reported evolve from application of a collection of mappings on the complex plane defined by a particular collection of Schwarz-Christoffel transformations.     

Infant visual acuity as a function of viewing distance.

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.     

Radial localization of odors by human newborns.

To study sensitivity to radial location of an odor source, 20 human newborns, ranging from 16 to 130 hours of age, were presented with a small amount of ammonium hydroxide. The odor source was placed near the nose slightly to the left or right of midline, with its position randomized over repeated trails. Direction of headturn with respect to the odor location and diffuse motor activity were scored from the videotape recordings of the newborns' behavior. It was found that as a group, the newborns turned away from the odor source more frequently than they turned toward it. The tendency to turn away from the odor was stronger in infants who displayed less motor activity after the response. Newborns also exhibited a right bias in the direction of the head movements. It is concluded that a spatially appropriate avoidance response is present in the neonate and that the newborn is innately sensitive to the radial location of an odor.     

The relative efficacy of vestibular-proprioceptive stimulation and the upright position in enhancing visual pursuit in neonates.

48 healthy neonates born to multiparae were randomly assigned to view a moving stimulus either in the horizontal or the upright position, with or without added vestibular stimulation and with or without pacifier sucking. The infant was shown a moving black line inside a strictly controlled visual environment provided by an apparatus which permitted horizontal and upright positioning and displacement of the infant. Visual tracking was recorded by a concealed TV camera positioned at a constant distance and angle from the infants' eyes in both positions. Quality of tracking during each of 4 trials was scored on a 7-point scale. Results indicate that vestibularproprioceptive stimulation provided to the infant either horizontally or semivertically significantly enhanced his visual tracking, whereas the upright position did not. Pacifier sucking also improved his performace.     

Problématique dans l'apprentissage de la mathématique

Sans résumé     

Research findings and administrative implications for off-campus higher education

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.

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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.

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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.