3,713 research outputs found

    Quantum Stochastic Processes: A Case Study

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    We present a detailed study of a simple quantum stochastic process, the quantum phase space Brownian motion, which we obtain as the Markovian limit of a simple model of open quantum system. We show that this physical description of the process allows us to specify and to construct the dilation of the quantum dynamical maps, including conditional quantum expectations. The quantum phase space Brownian motion possesses many properties similar to that of the classical Brownian motion, notably its increments are independent and identically distributed. Possible applications to dissipative phenomena in the quantum Hall effect are suggested.Comment: 35 pages, 1 figure

    Educational Research in Educational Practice: Predictors of Use

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    This study investigates the predictors of school practitioners’ (N = 2,425) use of educational research. The suggested model explained significantly but modestly the infrequent use of educational research by practitioners. Of the four factors in the study, “opinions about research” had the most explanatory power. The results are discussed in connection with existing knowledge about school practitioners’ use of educational research and implications for further research and practice

    From Preferred to Actual Mate Characteristics: The Case of Human Body Shape

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    The way individuals pair to produce reproductive units is a major factor determining evolution. This process is complex because it is determined not only by individual mating preferences, but also by numerous other factors such as competition between mates. Consequently, preferred and actual characteristics of mates obtained should differ, but this has rarely been addressed. We simultaneously measured mating preferences for stature, body mass, and body mass index, and recorded corresponding actual partner's characteristics for 116 human couples from France. Results show that preferred and actual partner's characteristics differ for male judges, but not for females. In addition, while the correlation between all preferred and actual partner's characteristics appeared to be weak for female judges, it was strong for males: while men prefer women slimmer than their actual partner, those who prefer the slimmest women also have partners who are slimmer than average. This study therefore suggests that the influences of preferences on pair formation can be sex-specific. It also illustrates that this process can lead to unexpected results on the real influences of mating preferences: traits considered as highly influencing attractiveness do not necessarily have a strong influence on the actual pairing, the reverse being also possible

    Flavonoids accumulate in cell walls, middle lamellae and callose-rich papillae during an incompatible interaction between Xanthomonas campestris pv. malvacearum and cotton

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    Interactions between cotton cotyledons and #Xanthomonas campestris pv. #malvacearum were examined. During an incompatible interaction, fluorescence microscopy revealed that flavonoid compounds accumulated within 10 h after inoculation. Electron micrographs showed ultrastructural modifications of cells that exhibited an intense fluorescence suggesting the presence of flavonoids. Phenol-like molecules were produced by cells of infection sites and were found in paramural areas within papillae enriched with callose and in host cell walls and middle lamellae. Histochemistry showed that peroxidase activity and terpenoids were detected in the infected resistant plants, 4 and 48 h after inoculation, respectively. In contrast, no changes in the deposits of lignin, suberin, and catechin were seen in either the infected susceptible or resistant lines. We suggest that early flavonoid accumulation is associated with the hypersensitive reaction of cotton cotyledons to #X. campestris pv. #malvacearum. The activity of wall-bound peroxidases may play a role in the incorporation of flavonoids in cell walls and paramural papillae. (Résumé d'auteur

    Isolement de linolénate de méthyle, un nouveau composé fongitoxique des feuilles d'arachide (Arachis hypogaea L.) infectées par Puccinia arachidis Speg.

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    Le linolénate de méthyle a été isolé de feuilles d'arachide infectées naturellement par #Puccinia arachidis$. Ce produit est un composé fongitoxique nouvellement identifié chez l'arachide. Sa purification, sa caractérisation et son activité fongitoxique sont décrites et son rôle dans les réactions de défense de l'hôte contre la rouille est discuté. (Résumé d'auteur

    Interactions insectes-plantes

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    Etiology of severe childhood pneumonia in the Gambia, West Africa, determined by conventional and molecular microbiological analyses of lung and pleural aspirate samples.

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    Molecular analyses of lung aspirates from Gambian children with severe pneumonia detected pathogens more frequently than did culture and showed a predominance of bacteria, principally Streptococcus pneumoniae, >75% being of serotypes covered by current pneumococcal conjugate vaccines. Multiple pathogens were detected frequently, notably Haemophilus influenzae (mostly nontypeable) together with S. pneumoniae
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