429 research outputs found

    Unitary nn-designs via random quenches in atomic Hubbard and Spin models: Application to the measurement of R\'enyi entropies

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    We present a general framework for the generation of random unitaries based on random quenches in atomic Hubbard and spin models, forming approximate unitary nn-designs, and their application to the measurement of R\'enyi entropies. We generalize our protocol presented in [Elben2017: arXiv:1709.05060, to appear in Phys. Rev. Lett.] to a broad class of atomic and spin lattice models. We further present an in-depth numerical and analytical study of experimental imperfections, including the effect of decoherence and statistical errors, and discuss connections of our approach with many-body quantum chaos.Comment: This is a new and extended version of the Supplementary material presented in arXiv:1709.05060v1, rewritten as a companion paper. Version accepted to Phys. Rev. A. Minus sign corrected in Eq (5

    Quantum simulation and optimization in hot quantum networks

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    Towards a codification of practical knowledge

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    International audienceAs practical knowledge seems to have a central place in organisational issues, we focus on possibilities to study and formalize it. From an unusual theoretical perspective, we view practical knowledge as embodied knowing which only is only manifest through action in a particular situation. Although this knowledge is largely implicit, we try to make what is 'articulable' explicit. After highlighting the stakes involved in the codification of practices, we review the ontological and epistemological assumptions underlying the method developed. It is founded on participant observation, a video recording of a situated subjective perspective and an ex post interview using this perspective to aid an actor to make part of his/her practical knowledge explicit. We present its implementation within research on polar expeditions in order to understand how an experienced actor deals with risks. In conclusion, we point out (1) the importance of this kind of data in knowledge management, (2) some lines of further research

    Réduire les risques alimentaires : un exemple d'évaluation économique

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    Diffusion du document : INRA Unité d'Economie et Sociologie rurales 65 rue de Saint-Brieuc 35042 Rennes Cedex (FRA)On constate une montée de la demande des consommateurs envers des produits alimentaires plus sûrs du point de vue de la santé humaine. Divers accidents récents comme l'encéphalopathie spongiforme bovine sont venus renforcer cette demande. Afin d'évaluer ces risques, une enquête exploratoire a été conduite dans la région de Rennes auprès de 311 personnes. Il s'agissait de tester la possibilité d'utiliser la méthode d'évaluation contingente dans un tel contexte. Les résultats obtenus sont encourageants, montrant que la méthode peut être mise en œuvre sans trop de problèmes. Il apparaît qu'il existe une acceptation à payer d'environ 4 à 6 % du prix des produits selon que l'on considère les fruits et légumes, ou la viande. Toutefois, on constate que les critères d'apparence restent déterminants dans les choix du consommateur

    Measuring treatment satisfaction in MS: Is the Treatment Satisfaction Questionnaire for Medication fit for purpose?

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    BACKGROUND: The Treatment Satisfaction Questionnaire for Medication (TSQM) was designed to assess patient treatment satisfaction in chronic diseases. Its performance has not been examined in multiple sclerosis (MS). The 14 items of the TSQM cover four domains: Effectiveness, Side Effects, Convenience, and Global Satisfaction. OBJECTIVE: To evaluate performance of the TSQM in patients with relapsing MS, using data collected from the TENERE study (NCT00883337), in which 324 patients received oral teriflunomide or subcutaneous interferon beta-1a for ⩾48 weeks. METHODS: Five measurement properties were examined using traditional psychometric methods: data completeness, scale-to-sample targeting, scaling assumptions, reliability (including test-retest), and construct validity (internal: item-level scaling success, confirmatory factor analysis, and exploratory factor analysis; external: convergence, discrimination, and group differences). RESULTS: There were few ( 0.90). Internal validity tests supported item groupings. Correlations supported convergent and discriminant construct validity; hypothesis testing supported group differences validity. CONCLUSION: This investigation found the TSQM to be a useful tool, exhibiting good psychometric measurement properties in patients with relapsing MS in the TENERE study
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