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Equivalent linearization consists in replacing a nonlinear system with an equivalent linear one whose parameters are tuned with regard to the minimization of a suitable function. In particular, the Gaussian equivalent linearization expresses the properties of an equivalent linear system in terms of the mean vector and the covariance matrix of the responses, which are the unknowns of the optimization problem in a spectral approach. Even though the system has been linearized, the resulting set of equations is nonlinear. The computational effort in this method pertains to the solution of a possibly large set of nonlinear algebraic equations involving integrals and inversions of full matrices. This work proposes to develop and apply an asymptotic expansion-based method to facilitate and to improve the statistical linearization for large nonlinear structures. The proposed developments demonstrate that for slightly to moderately coupled nonlinear systems, the equivalent linearization can be applied with an appropriate modal approach and eventually seen as a convergent series initiated with the stochastic response of a main decoupled linear system. With this method, the computational effort is attractively reduced, the conditioning of the set of nonlinear algebraic equations is improved and inversion of full transfer matrices and repeated integrations are avoided. The paper gives a formal description of the method and illustrates its implementation and performances with the computation of stationary responses of nonlinear structures subject to coherent random excitation fields. [ABSTRACT FROM AUTHOR]

Abstract: The use of normal modes of vibration in the analysis of structures with non-proportional damping reduces the size of the resulting set of governing equations, but does not decouple them. A common practice consists in decoupling the equations by disregarding the off-diagonal elements in the modal damping matrix. Recently, an approximation based on an asymptotic expansion of the modal transfer matrix has been proposed in a deterministic framework to partially account for off-diagonal terms, but still with a set of uncoupled equations. This paper aims at extending this method in a stochastic context. First the mathematical background is introduced and the method is illustrated with a simple example. Then its relevance is demonstrated within the context of the structural analysis of a large and realistic structure. [Copyright &y& Elsevier]

Abstract: Objectives: To assess physician compliance with guidelines for surgical antimicrobial prophylaxis practices and to identify factors associated with non-compliance. Patients and method: In a prospective study of patients admitted for clean or clean contaminated surgery from February 1 to April 28, 2008, we assessed appropriateness of surgical antimicrobial prophylaxis indication (recommended and prescribed or not recommended and not prescribed) and administration (antimicrobial choice, dose, timing and duration). Overall compliance was achieved if all criteria of indication and administration were met. The overall non-compliance rate was estimated and was used as a dependent variable in a multivariate logistic regression analysis to identify factors associated with non-compliance. Results: In a total of 481 practices evaluated, appropriateness of indication and administration of surgical prophylaxis were respectively 83% and 56%. The overall compliance rate to guidelines for surgical antimicrobial prophylaxis was 37%. In a multivariate regression analysis, prescription of antimicrobial prophylaxis by a surgeon (RR: 3.4; CI 95%: 1.6–7.5), clean-contaminated surgery (RR: 2.2; CI 95%: 1.4–3.7), traumatology surgery (1.87; 1.1–3.3), digestive surgery (3.7; 1.8–7.5) and head or neck-related surgery (11.4; 2.3–56.3) were independent factors associated with non-compliance to guidelines for surgical antimicrobial prophylaxis. Conclusion: This study confirmed previous findings on the impact of the type of surgery and the wound class contamination on the overall compliance rate. Furthermore, non-compliance was related to surgeon prescriptions. The compliance should be improved by specific measures after professional feedback. [Copyright &y& Elsevier]

Introduction Le traitement préventif des reviviscences de paludisme à Plasmodium vivax préconisé par l’OMS est la primaquine à la dose de 15 mg/j pendant 14 jours. Mais en raison d’une augmentation du nombre de reviviscences post traitement notamment en Asie du sud-est, le CDC préconise depuis 2006 l’utilisation de primaquine à la dose de 30 mg/j. En France, les cas importés de paludisme à P . vivax sont traités à cette posologie selon l’avis du Haut Conseil de la santé publique en 2008. Cette augmentation de posologie ne semble pas justifiée en Guyane et expose potentiellement à la survenue plus fréquente d’effets indésirables à la dose de 30 mg/j. L’objectif de cette étude était de comparer l’efficacité de deux posologies de primaquine (15 vs 30 mg/j pendant 14 jours) pour la prévention des reviviscences de P . vivax de l’adulte dans notre hôpital du 01/01/2007 au 01/08/2016. Matériels et méthodes Pour repérer les cas de reviviscence, nous avons exploré la base de données du laboratoire de parasitologie et le dossier médical de chacun des patients, en considérant la période de 6 mois à partir de la date du traitement par primaquine. Les cas survenant au-delà de 6 mois en zone d’endémie ont été considérés comme des nouvelles infections. Une description par courbe de Kaplan-Meier a été effectuée pour comparer la survenue d’évènements selon le dosage de primaquine utilisé. Un test du log rank a été utilisé pour comparer les deux groupes de traitement. Résultats Le nombre de patients inclus était de 464, âgés de 35 (± 12) ans, avec un sex-ratio H/F de 3,5. Ils étaient 236 à avoir reçu 15 mg/j, et 228 à avoir reçu 30 mg/j de primaquine. Les patients ont été traités à la dose de 15 mg/kg avant 2011, et 30 mg/kg après 2011. Le nombre de reviviscences était de 26 (11,0 %) et de 27 (11,8 %) à 15 et 30 mg/j, respectivement. Le test du log rank ne met pas en évidence de différence entre les deux groupes ( p = 0,76). Conclusion Ces résultats préliminaires ne montrent pas de différence d’efficacité entre les posologies de primaquine à 15 mg/j et 30 mg/j pendant 14 jours pour des cas d’infections à Plasmodium vivax survenus en Guyane. [ABSTRACT FROM AUTHOR]