Utilisation d'un algorithme d'interpolation de données irrégulièrement réparties pour l'estimation et la compensation de mouvement dans une séquence d'images

Dans ce papier, nous présentons une nouvelle modélisation du mouvement. Cette modélisation est issue d'une technique d'interpolation à partir d'échantillons irréguliers. Elle permet à partir d'un nombre limité de vecteur-échantillons de construire un champ dense de vecteurs. L'optimisation des paramètres liés aux vecteur-échantillons conduit à un champ dense de vecteurs minimisant l'erreur de compensation. Des résultats en terme de qualité de compensation en mouvement et en terme de codage sont donnés

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/)

2,2 '-biphosphinines and 2,2 '-bipyridines in homoleptic dianionic group 4 complexes and neutral 2,2 '-biphosphinine group 6 d(6) metal complexes: Octahedral versus trigonal-prismatic geometries

International audienceOne geometric and electronic structure of formally d(6) tris-biphosphinine [M(bp)(3)](q) and tris-bipyridine [M(bPY)(3)](q) complexes were studied by means of DFT calculations with the B3LYP functional. In agreement with the available experimental data, Group 4 dianionic [M(bp)(3)](2-) complexes (1P-3P for M=Ti, Zr, and Hf, respectively) adopt a trigonal-prismatic (TP) structure, whereas the geometry of their nitrogen analogues [M(bpy)(3)](2-)(1N-3N) is nearly octahedral (OC), although a secondary minimum was found for the TP structures (1N'-3N'). The electronic factors at work in these systems are discussed by means of an MO analysis of the minima, MO correlation diagrams, and thermodynamic cycles connecting the octahedral and trigonal-prismatic limits. In all these complexes, pronounced electron transfer from the metal center to the lowest lying pi* ligand orbitals makes the d(6) electron count purely formal. However, it is shown that the bp and bpy ligands accommodate the release of electron density from the metal in different ways because of a change in the localization of the HOMO, which is a mainly metal-centered orbital in bp complexes and a pure pi* ligand orbital in bpy complexes. The energetic evolution of the HOMO allows a simple rationalization of the progressive change from the TP to the OC structure on successive oxidation of the [Zr(bp)(3)](2-) complex, a trend in agreement with the experimental structure of the monoanionic complex. The geometry of Group 6 neutral complexes [M(bP)(3)] (4P and 5P for M=Mo and W, respectively) is found to be intermediate between the TP and OC limits, as previously shown experimentally for the tungsten complex. The electron transfer from the metal center to the lowest lying pi* ligand orbitals is found to be significantly smaller than for the Group 4 dianionic analogues. The geometrical change between [Zr(bP)(3)](2-) and [W(bp)(3)] is analyzed by means of a thermodynamic cycle and it is shown that a larger ligand-ligand repulsion plays an important role in favoring the distortion of the tungsten complex away from the TP structure

HYPERBAR, Applicabilité de la technologie Haute Pression en Biotechnologie

International audienceLa technologie des hautes pressions isostatiques est bien connue en agroalimentaire, car elle permet de réduire la charge bactérienne et virale de produits alimentaires. Pourtant en 2006, elle était encore complètement inconnue du monde pharmaceutique où cette technologie constituerait un facteur clé de compétitivité pour la production de vaccins. C’est pourquoi le groupe Mérial a fait appel à l’expertise technologique et scientifique du réseau de technologie des hautes pressions du CNRS. Labellisé par Lyonbiopôle fin 2006, le projet FUI « HYPERBAR », porté par Mérial, le Laboratoire Unité de Biologie Structurale des Interactions entre Virus et cellule Hôte de l’Université de Grenoble, le réseau des Hautes Pressions du CNRS et Top Industrie, le projet HYPERBAR se proposait d’évaluer la faisabilité d’inactivation de bactéries et de virus d’intérêt vaccinal et d’évaluer également la solubilisation et le repliement de protéines recombinantes à destinée pharmaceutique. Dans le même temps, la faisabilité de réalisation d’un équipement haute pression de qualité pharmaceutique était étudiée

Selective spectral modulation of strongly coupled spins with an echo top refocusing pulse in PRESS sequences.: Selective Modulation of Strongly Coupled Spins

International audienceThe double spin echo is the basis of the point resolved spectroscopy (PRESS) sequence. In this study we sought to investigate the effects of a broadband 180° pulse - incorporated in the PRESS sequence at the location of the first echo (gPRESS) - on the citrate resonances, chosen as a model of strongly coupled spin system. A significant signal modulation generated by the additional 180° pulse was predicted with simulations and observed experimentally in the citrate resonances. No effects were observed on the singlet resonance of glycine and the weakly coupled resonances of lactate. The phenomenon observed in gPRESS was attributed to the off-diagonal Hamiltonian elements responsible for a coherence transfer occurring throughout the evolution periods. The results of this study show that it is necessary to assess the effects of broadband 180° pulses on strongly coupled spin systems, since these pulses can selectively modify the spectral shape of strongly coupled resonances

D/H diffusion in serpentine

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Deuterium‑hydrogen inter-diffusion in chlorite

International audienceInteractions between aqueous fluids and rocks occur in a broad range of contexts ranging from hydrothermal alteration veins to regional metamorphism. Tracking these processes and understanding their reaction kinetics require a precise knowledge of the diffusion of water in rocks, and of isotope fractionation in major minerals, such as chlorite. Deuterium‑hydrogen exchange between Mg-rich chlorite and water (D2O) was experimentally investigated using a belt press over the temperature range of 315–650 °C at pressures of 1.5 GPa and 3 GPa. Both chloritite chip and chlorite powder were used. D/(D + H) ratios in chlorite grains were mapped using Raman spectroscopy. Deuterium‑hydrogen exchange proceeded by deuterium‑hydrogen inter-diffusion in chlorite (lattice diffusion). As chlorite is a phyllosilicate, i.e. an anisotropic mineral, diffusion coefficients were determined for crystallographic directions parallel and perpendicular to the silicate layers (perpendicular and parallel to the c* axis, respectively). Arrhenius relations for deuterium‑hydrogen inter-diffusion coefficients were derived from the new dataset. Activation energy (E) is comprised between 215 ± 21 (1σ) kJ/mol (perpendicular to the c* axis) and 194 ± 21 kJ/mol (parallel to the c* axis). Log10(D0) is −2.2 ± 1.3 m2/s for diffusion in the direction perpendicular to the c* axis and −4.5 ± 1.3 m2/s for diffusion parallel to it. The bulk diffusion law derived from a combination of our data with data from Graham et al. (1987) yields E = 176 ± 8 kJ/mol and log10(D0) = −5.1 ± 0.4 m2/s

Drying behavior of a single droplet of milk protein suspension

Thèse CIFRE confidentielle => pour plus d'info contacter Romain Jeantet et Pierre Schuck : UMR 1253 Science et Technologie du Lait et de l'Oeuf. STLO, (Institut supérieur des sciences agronomiques, agroalimentaires, horticoles et du paysage), Centre de recherche de Rennesabsen

Shape, shell, and vacuole formation during the drying of a single concentrated whey protein droplet

International audienceThe drying of milk concentrate droplets usually leads to specific particle morphology influencing their properties and their functionality. Understanding how the final shape of the particle is formed therefore represents a key issue for industrial applications. In this study, a new approach to the investigation of droplet−particle conversion is proposed. A single droplet of concentrated globular proteins extracted from milk was deposited onto a hydrophobic substrate and placed in a dry environment. Complementary methods (high-speed camera, confocal microscopy, and microbalance) were used to record the drying behavior of the concentrated protein droplets. Our results showed that whatever the initial concentration, particle formation included three dynamic stages clearly defined by the loss of mass and the evolution of the internal and external shapes of the droplet. A new and reproducible particle shape was related in this study. It was observed after drying a smooth, hemispherical cap-shaped particle, including a uniform protein shell and the nucleation of an internal vacuole. The particle morphology was strongly influenced by the drying environment, the contact angle, and the initial protein concentration, all of which governed the duration of the droplet shrinkage, the degree of buckling, and the shell thickness. These results are discussed in terms of specific protein behaviors in forming a predictable and a characteristic particle shape. The way the shell is formed may be the starting point in shaping particle distortion and thus represents a potential means of tuning the particle morphology.Anglai

High pressure stability of Cs6C60.

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