Homogénéisation de la perméabilité d'un milieu fracturé anisotrope et rôle de la perméabilité transverse des fractures

Ce papier a pour but de proposer une méthodologie d'estimation de la perméabilité macroscopique d'un milieu fracturé dans un cadre anisotrope quelconque en présence à la fois de micro-fractures mais aussi de fractures traversant le volume élémentaire représentatif. On adopte un modèle darcéen fictif pour représenter l'écoulement dans une fracture. Alors que la perméabilité tangentielle peut être fournie par référence à un écoulement de Poiseuille, on montre que le choix de la perméabilité transverse n'est pas intrinsèque : il est nécessaire que celle-ci soit faible dans le cas de fractures traversantes et plutôt élevée dans le cas de micro-fractures. On propose finalement des mises en oeuvre numériques ainsi qu'une comparaison avec des calculs sur réseaux explicites en 2D

Electron energy loss spectroscopy determination of Ti oxidation state at the (001) LaAlO3/SrTiO3 interface as a function of LaAlO3 growth conditions

At the (001) interface between the two band-insulators LaAlO3 and SrTiO3, a high-mobility electron gas may appear, which has been the object of numerous works over the last four years. Its origin is a subject of debate between the interface polarity and unintended doping. Here we use electron energy loss 'spectrum images', recorded in cross-section in a scanning transmission electron microscope, to analyse the Ti3+ ratio, characteristic of extra electrons. We find an interface concentration of Ti3+ that depends on growth conditions.Comment: 6 page

Approche d'homogénéisation des matériaux à microstructures complexes: Cas des bétons recyclés

Dans ce travail, nous revisitons dans un premier temps le problème d'Eshelby ([1]) pour des inhomogénéités composites de type ""motif morphologique représentatif"" ([2]). Le cas des inhomogénéités composites ou non ellipsoïdales a été déjà traité sous forme analytique pour des motifs à sphères concentriques ([3]), sous forme semi-analytique pour des motifs à ellipsoides confocaux ([4]) ou encore sous forme numérique pour des cas plus complexes ([2],[5]). Pour ce dernier cas, nous proposons un modèle numérique qui, moyennant une reformulation de la condition aux limites, permet de résoudre le problème de l'inhomogénéité avec un coût de calcul moindre que les méthodes classiques de résolution numérique du problème d'Eshelby sur un domaine supposé très grand. Dans un second temps, nous présentons une approche d'estimation des propriétés mécaniques effectives des milieux hétérogènes dans le cadre des motifs morphologiques composites complexes, cadre dans lequel, à défaut d'une solution analytique, le recours à une résolution numérique par éléments finis s'avère indispensable. Pour ce faire, le modèle éléments finis établi dans un premier temps a été couplé à un code d'homogénéisation pour rendre compte des propriétés mécaniques macroscopiques des matériaux à microstructures complexes comme les bétons recyclés ([6]) dont l'approche micromécanique conduit au problème de l'inhomogénéité composite. En application aux bétons recyclés justement, les propriétés mécaniques effectives de ces matériaux ont été déduites à partir des informations recueillies sur leurs microstructures grâce notamment à la nanoindentation (nature et propriétés mécaniques des granulats, des ITZ, du vieux mortier,...). L'effet des paramètres comme la fraction volumique des granulats recyclés ou de celui du vieux mortier dans le granulat recyclé sur les propriétés macroscopiques ont été aussi évalués. Enfin une confrontation avec les résultats expérimentaux est présentée en vue d'une validation du modèle. Bétons recyclés: bétons à base de granulats recyclés. Références [1] J. D, Eshelby. The Determination of the Elastic Field of an Ellipsoidal Inclusion, and Related Problems. Proc. R. Ser. A241 (A), 376-396. (1957). [2] André Zaoui. Structural Morphology and Constitutive Behaviour of Microheterogeneous Materials. BookTitle : Continuum Micromechanics. Editor : P. Suquet. Springer(1997). [3] Eveline Herve and Andre Zaoui. n-Layered inclusion-based micromechanical modelling.International Journal of Engineering Science (31) 1-10. (1993). [4] H.L.Duan and J. Wang and Z.P. Huang and Y.Zhong. Stress fields of a spheroidal inhomogeneity with an interphase in an infinite medium under remote loading. Proc. R. Soc. A (461) 1055-1080 (2005). [5] Fengjuan Chen and Igor Sevostianov and Albert Giraud and Dragan Grgic. Evaluation of the effective elastic and conductive properties of a material containing concave pores. Int. Jour. of Eng. Science (97) 60-68 (2015). [6] Paula Folino and Hernãn Xarguay. Recycled aggregate concrete-Mechanical behavior under uniaxial and triaxial compression. Construction and Building Materials (56) 21-31. (2014). Approche d'homogénéisation des matériaux à microstructures complexes: Cas des bétons recyclé

Assessing renal graft function in clinical trials: Can tests predicting glomerular filtration rate substitute for a reference method?

Assessing renal graft function in clinical trials: Can tests predicting glomerular filtration rate substitute for a reference method?BackgroundIn clinical trials, comparison of renal graft function needs a rigorous determination of glomerular filtration rate (GFR). Since reference methods to measure GFR cannot be easily implemented, a number of tests predicting GFR are usually used. However, little is known about their validity in renal transplant patients. We aimed to compare the performances of six GFR tests with inulin clearance in this population.MethodsFive hundred consecutive inulin clearances performed in 294 renal transplant recipients with stable renal function were retrospectively selected. For each of them, we computed six estimates: the 24-hour creatinine clearance, the Cockcroft-Gault, Walser, Jelliffe, Nankivell, and Levey formulas. Their respective performance was assessed by correlation (simple linear regression), accuracy (dispersion of true error), and agreement (Bland and Altman method).ResultsEach GFR test closely correlated with inulin clearance (P < 0.0001). Comparisons between pairs of GFR tests did not show any significant difference in accuracy between the Levey, Jelliffe, and Walser formulas. Conversely, each of these formulas demonstrated a significant lower dispersion (P < 0.005) than the others. Nevertheless, all GFR tests displayed considerable lack of agreement with limits of agreement over 40mL/min/1.73m2 apart. The proportion of predicted GFR differing from inulin clearance by ± 10mL/min/1.73m2, ranged from 34% for the Jelliffe formula to 53% for the Nankivell's one.ConclusionNone of these formulas seems to be able to safely substitute for inulin clearance. In clinical trials, renal graft function should be preferably assessed using a reference method of GFR measurement

Intranasal sufentanil versus intravenous morphine for acute severe trauma pain: A double-blind randomized non-inferiority study.

BACKGROUND: Intravenous morphine (IVM) is the most common strong analgesic used in trauma, but is associated with a clear time limitation related to the need to obtain an access route. The intranasal (IN) route provides easy administration with a fast peak action time due to high vascularization and the absence of first-pass metabolism. We aimed to determine whether IN sufentanil (INS) for patients presenting to an emergency department with acute severe traumatic pain results in a reduction in pain intensity non-inferior to IVM. METHODS AND FINDINGS: In a prospective, randomized, multicenter non-inferiority trial conducted in the emergency departments of 6 hospitals across France, patients were randomized 1:1 to INS titration (0.3 μg/kg and additional doses of 0.15 μg/kg at 10 minutes and 20 minutes if numerical pain rating scale [NRS] > 3) and intravenous placebo, or to IVM (0.1 mg/kg and additional doses of 0.05 mg/kg at 10 minutes and 20 minutes if NRS > 3) and IN placebo. Patients, clinical staff, and research staff were blinded to the treatment allocation. The primary endpoint was the total decrease on NRS at 30 minutes after first administration. The prespecified non-inferiority margin was -1.3 on the NRS. The primary outcome was analyzed per protocol. Adverse events were prospectively recorded during 4 hours. Among the 194 patients enrolled in the emergency department cohort between November 4, 2013, and April 10, 2016, 157 were randomized, and the protocol was correctly administered in 136 (69 IVM group, 67 INS group, per protocol population, 76% men, median age 40 [IQR 29 to 54] years). The mean difference between NRS at first administration and NRS at 30 minutes was -4.1 (97.5% CI -4.6 to -3.6) in the IVM group and -5.2 (97.5% CI -5.7 to -4.6) in the INS group. Non-inferiority was demonstrated (p < 0.001 with 1-sided mean-equivalence t test), as the lower 97.5% confidence interval of 0.29 (97.5% CI 0.29 to 1.93) was above the prespecified margin of -1.3. INS was superior to IVM (intention to treat analysis: p = 0.034), but without a clinically significant difference in mean NRS between groups. Six severe adverse events were observed in the INS group and 2 in the IVM group (number needed to harm: 17), including an apparent imbalance for hypoxemia (3 in the INS group versus 1 in the IVM group) and for bradypnea (2 in the INS group versus 0 in the IVM group). The main limitation of the study was that the choice of concomitant analgesics, when they were used, was left to the discretion of the physician in charge, and co-analgesia was more often used in the IVM group. Moreover, the size of the study did not allow us to conclude with certainty about the safety of INS in emergency settings. CONCLUSIONS: We confirm the non-inferiority of INS compared to IVM for pain reduction at 30 minutes after administration in patients with severe traumatic pain presenting to an emergency department. The IN route, with no need to obtain a venous route, may allow early and effective analgesia in emergency settings and in difficult situations. Confirmation of the safety profile of INS will require further larger studies. TRIAL REGISTRATION: ClinicalTrials.gov NCT02095366. EudraCT 2013-001665-16

Loss of memory CD4+ T-cells in semi-wild mandrills (Mandrillus sphinx) naturally infected with species-specific simian immunodeficiency virus SIVmnd-1

Simian immunodeficiency virus (SIV) infection is found in a number of African primate species and is thought to be generally non-pathogenic. However, studies of wild primates are limited to two species, with SIV infection appearing to have a considerably different outcome in each. Further examination of SIV-infected primates exposed to their natural environment is therefore warranted. We performed a large cross-sectional study of a cohort of semi-wild mandrills with naturally occurring SIV infection, including 39 SIV-negative and 33 species-specific SIVmnd-1-infected animals. This study was distinguished from previous reports by considerably greater sample size, examination of exclusively naturally infected animals in semi-wild conditions and consideration of simian T-lymphotropic virus (STLV) status in addition to SIVmnd-1 infection. We found that SIVmnd-1 infection was associated with a significant and progressive loss of memory CD4(+) T-cells. Limited but significant increases in markers of immune activation in the T-cell populations, significant increases in plasma neopterin and changes to B-cell subsets were also observed in SIV-infected animals. However, no increase in plasma soluble CD14 was observed. Histological examination of peripheral lymph nodes suggested that SIVmnd-1 infection was not associated with a significant disruption of the lymph node architecture. Whilst this species has evolved numerous strategies to resist the development of AIDS, significant effects of SIV infection could be observed when examined in a natural environment. STLVmnd-1 infection also had significant effects on some markers relevant to understanding SIV infection and thus should be considered in studies of SIV infection of African primates where present.The International Centre for Medical Research, Franceville, Gabon is funded by the Gabonese Government, Total-Gabon and the French Foreign Ministry. E. J. D. G. was funded by a PhD studentship provided by the Wellcome Trust and F. S. by the Biotechnology and Biological Sciences Research Council. Additional travel funds for E. J. D. G. and F. S. were provided by Hughes Hall, Cambridge and the Charles Slater Fund, respectively

Gut dysbiosis during influenza contributes to pulmonary pneumococcal superinfection through altered short-chain fatty acid production

Secondary bacterial infections often complicate viral respiratory infections. We hypothesize that perturbation of the gut microbiota during influenza A virus (IAV) infection might favor respiratory bacterial superinfection. Sublethal infection with influenza transiently alters the composition and fermentative activity of the gut microbiota in mice. These changes are attributed in part to reduced food consumption. Fecal transfer experiments demonstrate that the IAV-conditioned microbiota compromises lung defenses against pneumococcal infection. In mechanistic terms, reduced production of the predominant short-chain fatty acid (SCFA) acetate affects the bactericidal activity of alveolar macrophages. Following treatment with acetate, mice colonized with the IAV-conditioned microbiota display reduced bacterial loads. In the context of influenza infection, acetate supplementation reduces, in a free fatty acid receptor 2 (FFAR2)-dependent manner, local and systemic bacterial loads. This translates into reduced lung pathology and improved survival rates of double-infected mice. Lastly, pharmacological activation of the SCFA receptor FFAR2 during influenza reduces bacterial superinfection

Transition numérique et pratiques de recherche et d’enseignement supérieur en agronomie, environnement, alimentation et sciences vétérinaires à l’horizon 2040.

Pour citer ce document:Barzman M. (Coord.), Gerphagnon M. (Coord.), Mora O. (Coord.),Aubin-Houzelstein G., Bénard A., Martin C., Baron G.L, Bouchet F., Dibie-Barthélémy J., Gibrat J.F., Hodson S., Lhoste E., Moulier-Boutang Y., Perrot S., Phung F., Pichot C., Siné M., Venin T. 2019. Transition numérique et pratiques de recherche et d’enseignement supérieur en agronomie, environnement, alimentation et sciences vétérinaires à l’horizon 2040.INRA, France, 161pagesTransition numérique et pratiques de recherche et d’enseignement supérieur en agronomie, environnement, alimentation et sciences vétérinaires à l’horizon 2040

Measuring universal health coverage based on an index of effective coverage of health services in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

© 2020 Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license Background: Achieving universal health coverage (UHC) involves all people receiving the health services they need, of high quality, without experiencing financial hardship. Making progress towards UHC is a policy priority for both countries and global institutions, as highlighted by the agenda of the UN Sustainable Development Goals (SDGs) and WHO's Thirteenth General Programme of Work (GPW13). Measuring effective coverage at the health-system level is important for understanding whether health services are aligned with countries' health profiles and are of sufficient quality to produce health gains for populations of all ages. Methods: Based on the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019, we assessed UHC effective coverage for 204 countries and territories from 1990 to 2019. Drawing from a measurement framework developed through WHO's GPW13 consultation, we mapped 23 effective coverage indicators to a matrix representing health service types (eg, promotion, prevention, and treatment) and five population-age groups spanning from reproductive and newborn to older adults (≥65 years). Effective coverage indicators were based on intervention coverage or outcome-based measures such as mortality-to-incidence ratios to approximate access to quality care; outcome-based measures were transformed to values on a scale of 0–100 based on the 2·5th and 97·5th percentile of location-year values. We constructed the UHC effective coverage index by weighting each effective coverage indicator relative to its associated potential health gains, as measured by disability-adjusted life-years for each location-year and population-age group. For three tests of validity (content, known-groups, and convergent), UHC effective coverage index performance was generally better than that of other UHC service coverage indices from WHO (ie, the current metric for SDG indicator 3.8.1 on UHC service coverage), the World Bank, and GBD 2017. We quantified frontiers of UHC effective coverage performance on the basis of pooled health spending per capita, representing UHC effective coverage index levels achieved in 2019 relative to country-level government health spending, prepaid private expenditures, and development assistance for health. To assess current trajectories towards the GPW13 UHC billion target—1 billion more people benefiting from UHC by 2023—we estimated additional population equivalents with UHC effective coverage from 2018 to 2023. Findings: Globally, performance on the UHC effective coverage index improved from 45·8 (95% uncertainty interval 44·2–47·5) in 1990 to 60·3 (58·7–61·9) in 2019, yet country-level UHC effective coverage in 2019 still spanned from 95 or higher in Japan and Iceland to lower than 25 in Somalia and the Central African Republic. Since 2010, sub-Saharan Africa showed accelerated gains on the UHC effective coverage index (at an average increase of 2·6% [1·9–3·3] per year up to 2019); by contrast, most other GBD super-regions had slowed rates of progress in 2010–2019 relative to 1990–2010. Many countries showed lagging performance on effective coverage indicators for non-communicable diseases relative to those for communicable diseases and maternal and child health, despite non-communicable diseases accounting for a greater proportion of potential health gains in 2019, suggesting that many health systems are not keeping pace with the rising non-communicable disease burden and associated population health needs. In 2019, the UHC effective coverage index was associated with pooled health spending per capita (r=0·79), although countries across the development spectrum had much lower UHC effective coverage than is potentially achievable relative to their health spending. Under maximum efficiency of translating health spending into UHC effective coverage performance, countries would need to reach $1398 pooled health spending per capita (US$ adjusted for purchasing power parity) in order to achieve 80 on the UHC effective coverage index. From 2018 to 2023, an estimated 388·9 million (358·6–421·3) more population equivalents would have UHC effective coverage, falling well short of the GPW13 target of 1 billion more people benefiting from UHC during this time. Current projections point to an estimated 3·1 billion (3·0–3·2) population equivalents still lacking UHC effective coverage in 2023, with nearly a third (968·1 million [903·5–1040·3]) residing in south Asia. Interpretation: The present study demonstrates the utility of measuring effective coverage and its role in supporting improved health outcomes for all people—the ultimate goal of UHC and its achievement. Global ambitions to accelerate progress on UHC service coverage are increasingly unlikely unless concerted action on non-communicable diseases occurs and countries can better translate health spending into improved performance. Focusing on effective coverage and accounting for the world's evolving health needs lays the groundwork for better understanding how close—or how far—all populations are in benefiting from UHC. Funding: Bill & Melinda Gates Foundation