Impact of outpatient neuraminidase inhibitor treatment in patients infected with influenza A(H1N1)pdm09 at high risk of hospitalization: an Individual Participant Data (IPD) meta-analysis

Background: While evidence exists to support the effectiveness of neuraminidase inhibitors (NAIs) in reducing mortality when given to hospitalized patients with A(H1N1)pdm09 virus infection, the impact of outpatient treatment on hospitalization has not been clearly established. We investigated the impact of outpatient NAI treatment on subsequent hospitalization in patients with A(H1N1)pdm09 virus infection. Methods: We assembled general community and outpatient data from 9 clinical centers in different countries collected between January 2009 and December 2010. We standardized data from each study center to create a pooled dataset and then used mixed-effects logistic regression modeling to determine the effect of NAI treatment on hospitalization. We adjusted for NAI treatment propensity and preadmission antibiotic use, including “study center” as a random intercept to account for differences in baseline hospitalization rate between centers. Results: We included 3376 patients with influenza A(H1N1)pdm09, of whom 3085 (91.4%) had laboratory-confirmed infection. Eight hundred seventy-three patients (25.8%) received outpatient or community-based NAI treatment, 928 of 2395 (38.8%) with available data had dyspnea or respiratory distress, and hospitalizations occurred in 1705 (50.5%). After adjustment for preadmission antibiotics and NAI treatment propensity, preadmission NAI treatment was associated with decreased odds of hospital admission compared to no NAI treatment (adjusted odds ratio, 0.24; 95% confidence interval, 0.20–0.30). Conclusions: In a population with confirmed or suspected A(H1N1)pdm09 and at high risk of hospitalization, outpatient or community-based NAI treatment significantly reduced the likelihood of requiring hospital admission. These data suggest that community patients with severe influenza should receive NAI treatment

Impact of neuraminidase inhibitors on influenza A(H1N1)pdm09‐related pneumonia: an individual participant data meta‐analysis

BACKGROUND: The impact of neuraminidase inhibitors (NAIs) on influenza‐related pneumonia (IRP) is not established. Our objective was to investigate the association between NAI treatment and IRP incidence and outcomes in patients hospitalised with A(H1N1)pdm09 virus infection. METHODS: A worldwide meta‐analysis of individual participant data from 20 634 hospitalised patients with laboratory‐confirmed A(H1N1)pdm09 (n = 20 021) or clinically diagnosed (n = 613) ‘pandemic influenza’. The primary outcome was radiologically confirmed IRP. Odds ratios (OR) were estimated using generalised linear mixed modelling, adjusting for NAI treatment propensity, antibiotics and corticosteroids. RESULTS: Of 20 634 included participants, 5978 (29·0%) had IRP; conversely, 3349 (16·2%) had confirmed the absence of radiographic pneumonia (the comparator). Early NAI treatment (within 2 days of symptom onset) versus no NAI was not significantly associated with IRP [adj. OR 0·83 (95% CI 0·64–1·06; P = 0·136)]. Among the 5978 patients with IRP, early NAI treatment versus none did not impact on mortality [adj. OR = 0·72 (0·44–1·17; P = 0·180)] or likelihood of requiring ventilatory support [adj. OR = 1·17 (0·71–1·92; P = 0·537)], but early treatment versus later significantly reduced mortality [adj. OR = 0·70 (0·55–0·88; P = 0·003)] and likelihood of requiring ventilatory support [adj. OR = 0·68 (0·54–0·85; P = 0·001)]. CONCLUSIONS: Early NAI treatment of patients hospitalised with A(H1N1)pdm09 virus infection versus no treatment did not reduce the likelihood of IRP. However, in patients who developed IRP, early NAI treatment versus later reduced the likelihood of mortality and needing ventilatory support

Évaluation du transfert radiatif dans le coeur d'un Réacteur à Eau Pressurisée (REP) lors de la phase de renoyage d'un Accident de Perte de Réfrigérant Primaire (APRP)

We developped a method of resolution of radiative transfer inside a medium of vapor-droplets surrounded by hot walls, in order to couple it with a simulation of the flow at the CFD scale. The scope is the study of the cooling of the core of nuclear reactor following a Loss Of Coolant Accident (LOCA). The problem of radiative transfer can be cut into two sub problems, one concerning the evaluation of the radiative properties of the medium and a second concerning the solution of the radiative transfer equation. The radiative properties of the droplets have been computed with the use of the Mie Theory and those of the vapor have been computed with a Ck model. The medium made of vapor and droplets is an absorbing, anisotropically scattering, emissive, non grey, non homogeneous medium. Hence, owing to the possible variations of the flow properties (diameter and volumetric fraction of the droplets, temperature and pressure of the vapor), the medium can be optically thin or thick. Consequently, a method is required which solves the radiative transfer accurately, with a moderate calculation time for all of these prerequisites. The IDA has been chosen, derived from the well-known P1-approximation. Its accuracy has been checked on academical cases found in the literature and by comparison with experimental data. Simulations of LOCA flows have been conducted taking account of the radiative transfer, evaluating the radiative fluxes and showing that radiative transfer influence cannot be neglectedOn développe une méthode de résolution du transfert radiatif au sein d'un milieu vapeur-gouttelettes entouré de parois chaudes, en vue d'un couplage avec une résolution de l'écoulement à l'échelle de la CFD. Le domaine d'application considéré est l'étude du refroidissement du coeur d'une centrale nucléaire suite à un Accident de Perte de Réfrigérant Primaire (APRP). Le problème du transfert radiatif se découpe en deux sous-problèmes, l'un concernant l'évaluation des propriétés radiatives du milieu et le second la résolution du transfert radiatif. Les propriétés radiatives ont été calculées avec la théorie de Mie pour les gouttelettes et le modèle C-k pour la vapeur d'eau. On obtient un milieu absorbant, diffusant anisotrope, émissif, non gris et non homogène. De plus, compte tenu de la grande gamme possible des propriétés de l'écoulement (diamètre et concentration des gouttelettes, température et pression de la vapeur), le milieu peut être optiquement fin ou optiquement épais. Il faut donc une méthode de résolution du transfert radiatif efficace pour toutes les conditions observées dans un APRP et ayant un temps de calcul raisonnable en vue du couplage avec les autres modes de transferts. La méthode IDA, dérivée de l'approximation P1, a été choisie. Son niveau de précision a été validé sur des cas tests académiques et une expérimentation. Des simulations en condition APRP ont ensuite été effectuées, permettant d'évaluer les flux rayonnés et confirmant que le transfert radiatif n'est pas négligeable dans cet acciden

Taking Accurate Account of Radiative Heat Transfer for the Simulation of Core Reflooding

International audienceThe reflooding of the reactor core during a loss-of-coolant accident (LOCA) in a pressurized water reactor is a rather complex conjugate heat transfer situation. In the mist flow regime downward from the quench front, the rod wall can reach temperatures up to 1400 K, and radiative heat transfer can play a significant role. The present study concerns the accurate numerical computation of radiative heat transfer throughout a subchannel with LOCA representative flow conditions resolved at a computational fluid dynamics–scale spatial discretization thus allowing the large gradients of two-phase-flow properties to be determined. The accuracy of several methods to solve the radiative transfer equations has been compared both in canonical test cases and in low-pressure LOCA conditions. The role of radiative transfer is obvious in all variables including those related to the dynamics of the flow. Analysis of the gap between the present estimation and a standard correlation has been performed. It leads to the conclusion that radiative transfer can be taken into account accurately by correlation as soon as well-defined radiative properties are considered. The transfer is very sensitive to droplet size and concentration and can be as large as the convective heat transfer

Evaluation du transfert radiatif dans un cœur de Réacteur à Eau Pressurisée (REP) lors de la phase de re-noyage d’un Accident de Perte de Réfrigérant Primaire (APRP)

National audienceDes études basées sur l’utilisation de la CFD ont été menée s dans le contexte de la phase de renoyage d’un Accident de Perte de Réfrigérant Primaire (APRP) d’une centrale nucléaire. Le logiciel Neptune_CFD permet de simuler des écoulements diphasiques avec transfert de masses et d’énergie. Le transfert radiatif entre les crayons du cœur du réacteur nucléaire et le milieu environnant, formé de vapeur et de gouttelettes, a notamment été étudié à l’aide d’une méthode IDA, dérivée de l’approximation P1. Ces études ont permis de montrer que, dans les configurations étudiées, le transfert radiatif contribue à hauteur d’environ 20% aux transferts de masse et d’ énergie

Evaluation du transfert radiatif dans un cœur de Réacteur à Eau Pressurisée (REP) lors de la phase de re-noyage d’un Accident de Perte de Réfrigérant Primaire (APRP)

National audienceDes études basées sur l’utilisation de la CFD ont été menée s dans le contexte de la phase de renoyage d’un Accident de Perte de Réfrigérant Primaire (APRP) d’une centrale nucléaire. Le logiciel Neptune_CFD permet de simuler des écoulements diphasiques avec transfert de masses et d’énergie. Le transfert radiatif entre les crayons du cœur du réacteur nucléaire et le milieu environnant, formé de vapeur et de gouttelettes, a notamment été étudié à l’aide d’une méthode IDA, dérivée de l’approximation P1. Ces études ont permis de montrer que, dans les configurations étudiées, le transfert radiatif contribue à hauteur d’environ 20% aux transferts de masse et d’ énergie

Effective thermal conductivity of open cell foams for gas-solid reactors.

International audienc

Réduction de modèle thermique par Méthode d'Identification Modale (MIM) pour déterminer la température de surface des composants de machine de fusion

National audienceUne méthode de réduction de modèle par Méthode d’Identification Modale a été mise en place afin de simuler la température de surface de composants face au plasma dans les machines de fusion. Une des difficultés à la mise en place de cette méthode est la prise en compt e d’un flux de chaleur très hétérogène sur la surface du composant. La méthode permet de fournir la température de surface transitoire du composant en un temps très réduit par rapport à des méthodes de référence de type éléments finis (MEF) (12 000 fois plus vite) pour une erreur en température de l’ordre de quelques pourcents

Inverse Radiation Problem with Infrared Images to Monitor Plasma-Facing Components Temperature in Metallic Fusion Devices

International audienceInfrared (IR) diagnostics are used to measure plasma-facing components (PFC) surface temperature in fusion devices. However, the interpretation of such images is complex in all-reflective environments because of unknown emissivity and multiple reflections issues. In order to assess these challenges an iterative inversion method based on a fast photonic model, the radiosity method, has been developed. The radiosity method is based on strong hypotheses including all diffuse surfaces. The inversion method allows retrieving the true surface temperature of PFC in two steps: a step of the target emissivity estimation in a baking scene and the use of the emissivity map to retrieve the temperature of metallic components with errors up to 3% during a plasma scenario

Adhesive bond testing between composite laminates by laser shockwave loading

"Assembling materials by adhesive bonding has several advantages compared to other joining methods such as the use of fasteners or welding. Fasteners require drilling holes in the parts to be joined and both fastening and welding require significant investment in machinery. For metals, welded joints also generally produce a mechanically weaker heat affected zone. Adhesive bonding also has significant advantages for polymer-matrix composites. Drilling through composites has the drawback of cutting load-bearing fibers with adverse effects of possible delamination and excessive tool wear. It may also be economically advantageous to bond several small parts to make a large structure instead of having it co-cured. However, for all materials, the use of adhesive bonding for loadbearing structures is impeded by the absence of reliable nondestructive methods that can guarantee the strength of the joint, and in particular are able to very reliably identify the presence of near zerostrength \u201ckissing bonds\u201d [1]. Kissing bonds are undetectable by conventional ultrasonic inspection since the return echo from the interface in the pulse-echo technique does not depend upon the bond strength and only requires mechanical contact between the adherends. This is also the case for the transmitted echo. Although there have been many attempts to develop other ultrasonic approaches, such as using waves that propagate essentially along the bond line, none of these approaches has succeeded in detecting a weak bond other than those that are weakened by defects such disbonds or porosity [1-3]. These defects can be detected by the well established ultrasonic inspection technique and in the case of porosity, also by x-ray radiography. Among possible causes of weak bonds are contamination of surfaces prior to bonding, inadequate surface preparation, degradation of the adhesive from improper storage, and inadequate mixing ratio for two-part adhesives. In all these cases, there can be good mechanical contact without defects, combined with poor mechanical strength, undetectable by established ultrasonic inspection techniques. Ultrasonic techniques only apply weak stresses to the bond line and such weak stresses cannot reveal characteristics that are only apparent by applying significant stresses, like in destructive tests. Therefore, a reliable technique to identify such weak bonds requires application of a strong tensile stress across the bond line. A convenient approach that has been previously studied for evaluating the dhesion of coatings to their substrate and fibers to their matrix uses a pulsed laser to generate a large amplitude wave (shockwave) that propagates throughout the material [4-9]. This wave, being initially in compression, is converted by reflection on the back surface of the sample into a strong tensile wave that can pry apart the sample and disbond the assembly. This approach has been more recently extended to proof testing of adhesive bonds between carbon-epoxy laminates [10,11]. To probe bond strength, higher and higher tensile stress loading is applied by increasing the laser pulse energy step by step. A \u201cgood\u201d joint will be unaffected under a given stress level whereas a weaker one will be damaged, allowing this method to evaluate the bond strength. The principle of the method is described next in more detail. We then describe how the ethod is implemented, the instrumentation that has been developed and the fabrication of weak bond test specimens. Finally we present some results and indicate erspectives and future developments.Peer reviewed: YesNRC publication: Ye