1000 resultados para Méthode adaptative


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The term visual field corresponds to the angular field of view that is seen by the eyes when they are fixed on a point straight-ahead. In neurological patients--e.g. stroke, trauma, or tumour patients--visual field function can be restricted, depending on lesion site and size. In contrast, the term "functional visual field" describes the area of visual field responsiveness under more ordinary viewing conditions. The visual exploration, i.e. the capacity to explore and analyze our visual world, is dependent on the integrity of the visual system and the oculomotor system which has to move the fovea from one object of interest to the next. In this paper, we present a new method to assess the functional visual field, conceptualized as the area that a patient actively scans with eye movements to detect predefined targets placed on everyday scenes. This method allows us to compare three levels of visual field function: (a) the spatial distribution of successful search (hits, i.e. which targets did the patient find?), (b) the spatial distribution of fixations (i.e. where did the patient preferentially search for targets?), and (c) the retinotopic level (i.e. the visual field assessed by perimetry). By integrating these three levels, one can evaluate functional outcomes of visual field disorders. Of particular importance is the question of how a patient compensates for a visual field loss with appropriate eye movements. A further clinical application of this method is the comparison of pre- with post-treatment data. Patients with visual field disorders usually undergo specific exploration trainings, aimed at enhancing the number and amplitude of saccades towards the region of the visual field deficit. The first experiences and clinical application with this method are presented here.

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à l'usage de la jeunesse Israélite par L.-M. Lambert

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par Léon Fridman

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• Premise of the study: Because not all plant species will be able to move in response to global warming, adaptive evolution matters largely for plant persistence. As prerequisites for adaptive evolution, genetic variation in and selection on phenotypic traits are needed, but these aspects have not been studied in tropical species. We studied how plants respond to transplantation to different elevations on Mt. Kilimanjaro, Tanzania, and whether there is quantitative genetic (among-seed family) variation in and selection on life-history traits and their phenotypic plasticity to the different environments. • Methods: We reciprocally transplanted seed families of 15 common tropical, herbaceous species of the montane and savanna vegetation zone at Mt. Kilimanjaro to a watered experimental garden in the montane (1450 m) and in the savanna (880 m) zone at the mountain’s slope and measured performance, reproductive, and phenological traits. • Results: Plants generally performed worse in the savanna garden, indicating that the savanna climate was more stressful and thus that plants may suffer from future climate warming. We found significant quantitative genetic variation in all measured performance and reproductive traits in both gardens and for several measures of phenotypic plasticity in response to elevational transplantation. Moreover, we found positive selection on traits at low and intermediate trait values levelling to neutral or negative selection at high values. • Conclusions: We conclude that common plants at Mt. Kilimanjaro express quantitative genetic variation in fitness-relevant traits and in their plasticities, suggesting potential to adapt evolutionarily to future climate warming and increased temperature variability.

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Fil: Daule, Gabriela. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Fil: Daule, Gabriela. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación; Argentina.

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Les méthodes d'optimisation statiques(c'est-a-dire des systemes dont les parametres n'.évoluent pas avec le temps) peuvent se diviser en deux grandes classes : les méthodes directes et les méthodes indirectes. Les premieres ocalisent le vecteur optimum par des mouvements tratégiques dans l'espace correspondant. Elles nécessitent la connaissance de la valeur de la fonction critere a chaque point, mais non la forme algébrique, ni ses dérivées.

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Dans le problème de la synthèse d'une machine séquentielle, on peut, grosso modo, distinguer trois étapes : le passage des données du système à construire à la représentation tabulée (table de fluence ou table des phases, dans le cas d'un système asynchrone);le codage des états internes de cette table (de façon,dans le cas d'une machine synchrone, à obtenir si possible une décomposition en sous-machines, et,dans le cas d'une machine asynchrone, de façon à éviter les phénomènes de courses et d'aléas); enfin,l'écriture des équations et le dessin du schéma logique de la machine (en essayant par exemple de minimaliser le nombre de composants nécessaires à la. réalisation du circuit).

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People in industrial societies carry more and more portable electronic devices (e.g., smartphone or console) with some kind of wireles connectivity support. Interaction with auto-discovered target devices present in the environment (e.g., the air conditioning of a hotel) is not so easy since devices may provide inaccessible user interfaces (e.g., in a foreign language that the user cannot understand). Scalability for multiple concurrent users and response times are still problems in this domain. In this paper, we assess an interoperable architecture, which enables interaction between people with some kind of special need and their environment. The assessment, based on performance patterns and antipatterns, tries to detect performance issues and also tries to enhance the architecture design for improving system performance. As a result of the assessment, the initial design changed substantially. We refactorized the design according to the Fast Path pattern and The Ramp antipattern. Moreover, resources were correctly allocated. Finally, the required response time was fulfilled in all system scenarios. For a specific scenario, response time was reduced from 60 seconds to less than 6 seconds.

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La détermination directe des caractéristiques de cisaillement des bétons par des essais universels est un problème qui reste encore une préoccupation majeure des chercheurs. La plupart des études disponibles consistent à appliquer un couple de torsion à un cylindre creux ayant un rapport épaisseur/rayon le plus faible possible. Ceci pour pouvoir élaborer un critère lié au comportement du matériau et non de la structure (Fourd et al. 1982). Cependant, ces essais peuvent présenter des dispersions liées aux problèmes de fragilité à la rupture ou de non homogénéité du matériau au sein de la paroi (Gotuwka et al. 1999). Pour cela, un dispositif expérimental original a été utilisé et qui consiste en la création de deux zones de contrainte nulle par l’emplacement de corps déformables au moment du coulage de l’éprouvette. De nouvelles conditions aux frontières sont créées permettant de transformer la sollicitation de compression en cisaillement plan sur une zone bien déterminée. L’utilisation de cette technique permet la détermination de l’influence de l’inclinaison du plan de rupture sur le comportement du béton en cisaillement. Le dispositif permet d’assurer la perpendicularité NOvEMBRE 2012 5 des génératrices du cylindre ainsi que la répartition et l’homogénéité des contraintes.