Upscaling Fractured Heterogeneous Media: Permeability and Mass Exchange Coefficient

In order to optimize oil recuperation, to secure waste storage, CO2 sequestration and describe more precisely many environmental problems in the underground, we need to improve some homogenization methods that calculate petrophysical parameters. In this paper, we discuss the upscaling of fluid transport equations in fractured heterogeneous media consisting of the fractures themselves and a heterogeneous porous matrix. Our goal is to estimate precisely the fluid flow parameters like permeability and fracture/matrix exchange coefficient at large scale. Two approaches are possible. The first approach consists in calculating the large-scale equivalent properties in one upscaling step, starting with a single continuum flow model at the local scale. The second approach is to perform upscaling in two sequential steps: first, calculate the equivalent properties at an intermediate scale called the ”unit scale,” and, second, average the flow equations up to the large scale. We have implemented the two approaches and applied them to randomly distributed fractured systems. The results allowed us to obtain valuable information in terms of sizes of representative elementary volume associated to a given fracture distribution

Environmental stressors may cause equine herpesvirus reactivation in captive Grévy’s zebras (Equus grevyi)

Equine Herpesviruses (EHV) are common and often latent pathogens of equids which can cause fatalities when transmitted to non-equids. Stress and elevated glucocorticoids have been associated with EHV reactivation in domestic horses, but little is known about the correlation between stress and viral reactivation in wild equids. We investigated the effect of an environmental stressor (social group restructuring following a translocation event) on EHV reactivation in captive Grévy’s zebras (Equus grevyi). A mare was translocated by road transport from Zoo Mulhouse, France, to join a resident group of three mares in Tierpark Berlin, Germany. We used an indirect sampling method to assess the frequency of EHV shedding for 14 days immediately after the translocation event (termed the ‘experimental period’). The results were compared with those from two control periods, one preceding and one subsequent to the experimental period. In addition, we measured fecal glucocorticoid metabolite (fGCM) concentrations daily in all individuals from 6 days before, to 14 days after translocation. We found significantly higher EHV shedding frequencies during the experimental period, compared to each of the two control periods. All animals showed significantly elevated fGCM concentrations, compared to fGCM levels before translocation. Finally, we found that an increase in fGCM concentration was significantly associated with an increased likelihood of EHV shedding. Although the small number of animals in the study limits the conclusions that can be drawn from the study, taken together, our results support the hypothesis that environmental stressors induce viral reactivation in wild equids. Our results suggest that potentials stressors such as group restructuring and translocation should be considered in the management of zoological collections to reduce the risk of fatal EHV infections in novel hosts. Moreover, environmental stressors may play an important role in EHV reactivation and spread in wild equid populations

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Etude expérimentale sur cobaye (Cavia aperea) de l'efficacité de deux vaccins contre la pseudotuberculose

La pseudotuberculose est une maladie infectieuse ubiquiste affectant de nombreuses espèces animales et responsable de nombreuses épizooties en parcs zoologiques. Ses manifestations frustes et jamais pathognomoniques rendent les traitements illusoires. Or très peu de moyens de prophylaxie médicale existent. Une expérimentation a donc été menée sur 60 cobayes afin de tester l'efficacité de 2 vaccins. L'épreuve virulente a été réalisée à l'aide de deux sérotypes de Yersinia pseudotuberculosis isolés sur des cas confirmés en zoos. L'étude clinique, bactériologique, lésionnelle et sérologique des animaux si elle a pu mettre en évidence une séroconversion et des tendances quant à la protection clinique mais n'a pas permis de démontrer statistiquement l'efficacité de l'un ou l'autre des vaccins.NANTES-Ecole Nat.Vétérinaire (441092302) / SudocSudocFranceF

Suivi du comportement sexuel chez 3 espèces de primates non-humains du genre Nomascus

Cette étude s’inscrit dans un suivi à long terme des effets d’un contraceptif progestatif sur le comportement reproducteur. Peu de données étant disponibles, un suivi de la reproduction, au préalable de l’implantation, est donc essentiel afin de définir des indicateurs comportementaux. Un échantillonnage par individu focal et un suivi hormonal sont effectués de manière concomitante sur 3 groupes de primates non-humains du genre Nomascus (N. siki, N. leucogenys et N. gabriellae). Les groupes sont constitués respectivement de (1) 1 mâle et sa progéniture : une femelle adulte, un mâle subadulte et un jeune ; (2) un mâle adulte, une femelle adulte et sa progéniture femelle adulte ; (3) un couple d’adultes, une femelle subadulte et un jeune. Le suivi comportemental, se déroulant sur 3 h, 15 minutes par individu, 5 jours par semaine de février à avril 2015, vise à repérer des différences dans le comportement de la femelle au cours du temps et si les variations observées sont en relation avec les variations hormonales. Au cours de ces 123 heures 45 minutes d'observations, des comportements sexuels ont pu être observés chez 2 des 3 groupes de Nomascus durant les 9 semaines d’observations. Au sein du groupe leucogenys, la plus jeune femelle émet 64 invitations et 1 accouplement tandis que la seconde émet 10 invitations et 1 présentation. Aucune différence significative dans le comportement n’est observée pour la femelle du groupe leucogenys. De plus il semble que l’émission des comportements reproducteurs n'est pas dépendante du niveau hormonal (corrélation de Spearman). Chez le groupe gabriellae, les deux femelles ont exprimé des comportements sexuels, 30 invitations et 10 accouplements et 3 présentations ont été émis par la femelle suivie hormonalement. La femelle subadulte a effectué 3 présentations. Il n’y a pas de différence significative dans le nombre ou la durée des interactions émises par la femelle N. gabriellae ni en fonction du temps ni en fonction du récepteur, cependant, la femelle interagit significativement plus (fréquence et durée) avec le mâle durant 3 des 9 semaines que le reste du temps (test de wilcoxon, p = 0,02268 et p = 0,001745). C’est lors de ces 3 semaines que les comportements reproducteurs ont été observés. L’expression des comportements reproducteurs n’est pas indépendante des niveaux hormonaux (corrélation de Spearman, p = 4,065.10-4). Au regard des résultats, il existe une indépendance relative entre les comportements reproducteurs et le contrôle hormonal. Il semble donc important de dissocier les comportements sexuels reproducteurs et sociaux. Un suivi comportemental de la reproduction est possible par l’observation de comportements sexuels discriminants. Cependant ces résultats sont à relativiser, car les observations n’ont porté que sur 5 % de la durée totale d’un cycle. De plus les comportements sexuels sont de courte durée et peuvent facilement échapper à l’observateur. Enfin un faible nombre de femelles et de cycles suivis (n = 2) ne permet pas de s’affranchir des variations individuelles. Pour cela il est nécessaire d’augmenter l’échantillonnage de femelles et de cycles.Je souhaite remercier l’ensemble des soigneurs du Parc zoologique et botanique de Mulhouse en particulier les soigneurs des secteurs lémuriens, le Dr J. Y. Georges pour son aide dans l’analyse des données et son savoir-faire

An efficient finite volume discretization to simulate flows on 3D discrete fracture network for transient flow analysis and equivalent permeability upscaling

The organization of natural fracture networks induces flow paths that control fluid flows in reservoirs. Taking into account all heterogeneities is computationally very costly, therefore, equivalent multi-porosity and multi-permeability models have to be used. We present an innovating discretization procedure allowing to simulate flow on 3D Discrete Fracture Networks involving over 100.000 fractures. We then demonstrate how to improve the computation of an equivalent permeability tensor by combining analytical and clever-meshed numerical solutions