La recherche sur l'apprentissage opérant chez le nourrisson : un parallèle avec l'état général de la question chez l'humain

Summary : Operant conditioning in infants : a parallel wiih the general situation in humans. Research on infants' operant behaviours has followed the methodological model devised to study behaviours of other species, in dissimilar contexts. The need to identify discrete and repetitive responses reinforced by discrete stimuli in order to meet wiih the demands of a response rate analysis, greatly limits the range of possible target-behaviours. Moreover, the control variables elaborated for the human contexts have little in common with those used with animais. In the first case, the variables are part of an ecological reinforcement paradigm, appropriate for exploration and problem solving settings. The temporary and differential reinforcing qualities of ecological stimuli have favoured the study of infants' perceptual and cognitive processes, without actually increasing our knowledge about learning processes per se. Therefore, it appears preferable to depart from the sole dependency on response rate changes as index of learning, and to study other behaviours that can be measured and analysed differently. Still, it is important to work, beforehand or in concomitance, on a conceptual frame-work that will go beyond the simple stage of post-hoc explanation. Research could be enlarged by the study of contingency conditions in a less usual perspective, particularly in terms of an analysis of the sufficiency and necessity of behaviours, and also of conjugale and synchrohous reinforce-ment. We examine the question of intra-individual behavioural variability, while distinguishing induced variability front reinforced variability. Thèse less studied concepts seem crucial to the opérant model. Key words : human opérant behaviour, opérant conditioning, contingency.Résumé La recherche sur les comportements opérants chez le nourrisson a suivi le modèle méthodologique mis au point pour étudier les comportements d'autres espèces. La nécessité d'identifier des réponses discrètes et répétitives, renforcées par des stimulus discrets, de façon à satisfaire les exigences d'une analyse de taux des réponses, limite la gamme des conduites cibles. De surcroît, les variables de contrôle dans les situations mises au point avec le nourrisson et l'humain en général ont peu en commun avec celles des situations utilisées avec l'animal. Dans le premier cas, ces variables s'insèrent dans un paradigme de renforcement écologique, aux effets temporaires, propre aux situations d'exploration et de solution de problème. Aussi convient-il de se départir de cette dépendance sur les seuls changements de taux comme indice d'apprentissage et étudier, dans des conditions de contingence moins habituelles, d'autres conduites qui se prêtent à des types de mesures et d'analyses différents. L'étude de la variabilité intra-individuelle des conduites, en distinguant la variabilité induite de la variabilité renforcée, est également cruciale pour le modèle opérant. Mots clés : conduites opérantes humaines, conditionnement opérant, contingence.Malcuit Gérard, Pomerleau Andrée, Lamarre Ginette. La recherche sur l'apprentissage opérant chez le nourrisson : un parallèle avec l'état général de la question chez l'humain. In: L'année psychologique. 1988 vol. 88, n°2. pp. 257-282

Specific inhibitors of HCV polymerase identified using an NS5B with lower affinity for template/primer substrate

The interaction of the hepatitis C virus (HCV) RNA-dependent RNA polymerase with RNA substrate is incompletely defined. We have characterized the activities of the HCV NS5B polymerase, modified by different deletions and affinity tags, with a routinely used homopolymeric substrate, and established apparent affinities of the various NS5B constructs both for the NTP and the template/primer substrates. We identified a uniquely tagged HCV NS5B RNA polymerase construct with a lower affinity (higher K(m)) than mature HCV NS5B for template/ primer substrate and highlighted the use of such a polymerase for the identification of inhibitors of NS5B activity, particularly inhibitors of productive RNA binding. The characterization of specific benzimidazole-5-carboxamide-based inhibitors, identified in a screening campaign, revealed that this class of compounds was non-competitive with regard to NTP incorporation and had no effect on processive elongation, but inhibited an initiation phase of the HCV polymerase activity. The potency of these compounds versus a panel of different NS5B polymerase constructs was inversely proportional to the enzymes’ affinities for template/primer substrate. The benzimidazole-5-carboxamide compounds also inhibited the full-length, untagged NS5B de novo initiation reaction using HCV 3′-UTR substrate RNA and expand the diversifying pool of potential HCV replication inhibitors

La pointe de l'iceberg : une étude pancanadienne sur la reconnaissance des acquis extrascolaires /

Comprend des références bibliographiques (pages 85-86

Réparation de poésie no 13 : Assembling

The 13th edition of this Quebec collective’s annual publication comprises Mail Art projects by 59 artists from ten countries. The works, which may include short poetic texts, employ drawing, collage, silkscreening, photocopying, painting and digital imagery; some incorporate objects, postcards or recycled, printed material. Themes include biotechnology, territory, daily life, happiness, violence, the family and the events of September 11, 2001. Texts in English, French, Italian and Spanish