Finite-temperature properties of frustrated classical spins coupled to the lattice

We present extensive Monte Carlo simulations for a classical antiferromagnetic Heisenberg model with both nearest ($J_1$) and next-nearest ($J_2$) exchange couplings on the square lattice coupled to the lattice degrees of freedom. The Ising-like phase transition, that appears for $J_2/J_1>1/2$ in the pure spin model, is strengthened by the spin-lattice coupling, and is accompanied by a lattice deformation from a tetragonal symmetry to an orthorhombic one. Evidences that the universality class of the transition does not change with the inclusion of the spin-lattice coupling are reported. Implications for ${\rm Li_2VOSiO_4}$, the prototype for a layered $J_1{-}J_2$ model in the collinear regime, are also discussed.Comment: 6 pages and 8 figure

Ising transition driven by frustration in a 2D classical model with SU(2) symmetry

We study the thermal properties of the classical antiferromagnetic Heisenberg model with both nearest ($J_1$) and next-nearest ($J_2$) exchange couplings on the square lattice by extensive Monte Carlo simulations. We show that, for $J_2/J_1 > 1/2$, thermal fluctuations give rise to an effective $Z_2$ symmetry leading to a {\it finite-temperature} phase transition. We provide strong numerical evidence that this transition is in the 2D Ising universality class, and that $T_c\to 0$ with an infinite slope when $J_2/J_1\to 1/2$.Comment: 4 pages with 4 figure

Prévalence des neuropathies optiques dans le syndrome d'apnée du sommeil

MONTPELLIER-BU Médecine UPM (341722108) / SudocMONTPELLIER-BU Médecine (341722104) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Maladie rénale chronique et troubles neurocognitifs

International audienceChronic kidney disease (CKD) affects 25% of people aged over 70 years. Cognitive impairment (CI) is frequent in patients with CKD and affects 30% to 60% of patients treated by hemodialysis. The link between CKD and CI is explained by common risk factors, such as hypertension and diabetes, but also by CKD-specific risk factors through vascular, degenerative, and toxic mechanisms. In patients with non-dialyzed CKD, albuminuria is more strongly linked to CI occurrence than glomerular filtration rate. Vascular dementia is the main cause of CI in patients with CKD, but incidence of Alzheimer's disease has also been found higher in patients with end-stage of kidney disease than in the general population. Executive functions, orientation and attention are the most frequently affected cognitive domains in patients with CKD. Occurrence of CI in older patients with CKD could be prevented by controlling blood pressure or the use of anticoagulant drugs in case of atrial fibrillation, which is particularly frequent in patients with CKD, in order to prevent cerebrovascular lesions. Nephrological care could also influence the occurrence of neurological complications. Anticholinesterasic drugs and memantine should be used with caution in patients with CKD, because most of these drugs accumulates in case of low glomerular filtration rate. Due to the poor prognosis of patients with CI and end-stage of kidney disease treated by dialysis or kidney transplantation, a cognitive assessment should be proposed to older patients with severe CKD in order to discuss the initiation and the type of renal replacement therapy with both patients and caregive

Using machine learning algorithms to link volumetric water content to complex dielectric permittivity in a wide (33-2000 MHz) frequency band for hydraulic concretes

This paper focuses on the development and validation of an innovative method for estimating volumetric water content in concrete mixtures. A supervised learning method (support vector machine) has been used to resolve the inverse problem, i.e., generate in-laboratory calibration curves correlating the controlled water content in various concrete mixtures with the frequency-dependent complex dielectric permittivity originating from the coaxial electromagnetic transition line. An extrapolation procedure using a frequency-power-law model has been developed and validated for estimating the complex permittivity over a broad frequency bandwidth. Implementation of this extrapolation method allows considering various physical phenomena (i.e., polarisation versus water content) that typically affect the dielectric behaviour of concrete as a function of frequency. The two-step estimation procedure (involving extrapolation and support vector regression methods) proposed in this paper has been validated on a wide array of moisture-controlled concrete specimens in the laboratory. The procedure helps building calibration curves that rely on both complex effective permittivity and volumetric water content, taking into consideration the frequency dependence

Mini-entretiens multiples : un outil pour la réforme de l’accès aux études en santé en France

Introduction : Depuis la loi de santé de 2019, les modalités d’accès aux études en maïeutique, médecine, odontologie et pharmacie comportent des épreuves écrites et, pour une partie des étudiants, au moins une épreuve orale. Les mini-entretiens multiples (MEM) permettent d’évaluer les capacités de communication, l’empathie ou les capacités de travail en groupe et sont moins biaisés que les entretiens individuels traditionnels. Cet article propose une revue narrative de la littérature afin d’évaluer la faisabilité des MEM dans le contexte français. Méthodes : Cet article de synthèse s’appuie sur une recherche bibliographique à partir de la base PubMed avec le mot clé « Multiple Mini Interview ». Les articles sélectionnés devaient traiter au moins une des questions suivantes relatives aux MEM : organisation, acceptabilité, compétences évaluées, prédiction des performances. Résultats : Les MEM ont été utilisés pour la sélection des candidats à de nombreuses filières en santé et dans de nombreux pays. Les résultats obtenus aux MEM à l’admission sont corrélés aux performances obtenues lors des stages cliniques et des ECOS durant le cursus universitaire. Cependant, certaines caractéristiques des candidats peuvent influer les résultats obtenus (âge, facteurs socio-économiques) et les MEM mobilisent de nombreux évaluateurs pour leur mise en œuvre. Conclusion : Les MEM sont une modalité d’évaluation reproductible et validée pour la sélection des étudiants en santé, en complément de l’évaluation des aptitudes cognitives. Ils devraient être largement utilisés pour la sélection des étudiants en santé en France, depuis la réforme de l’accès aux études en santé

Acoustic techniques for concrete evaluation: improvements, comparisons and consistency

In civil engineering, the testing of structures allows a large number of chemical, mechanical and micro–macro structural parameters to be determined. Within the scope of ultrasonic Non-Destructive Testing (NDT), which is often used to evaluate concrete, many different techniques can be employed to generate, propagate, and receive the ultrasound waves, and to process the corresponding signals. The SENSO project, developed by nine partners, provided an opportunity to test a large number of principles related to the material’s characteristics and properties. Concerning the acoustic techniques, the first approach was based on linear propagation with bulk waves and surface waves, or with backscattered waves. The second method involved nonlinear analysis using wave modulation. One aim of the SENSO project was to compare these different techniques, in order to select that having the most promising performance in the laboratory, before transferring the measurement techniques to the field. The objectives were to evaluate the porosity, degree of saturation, modulus of elasticity and compressive strength of concrete. In the present paper, the measurement techniques and measured parameters are presented, together with the improvements developed within the context of the SENSO project. The methodology used to classify and select the ultrasonic techniques is described. It takes into account the sensitivity of the method to changes in the material and associates measurement uncertainties. Finally, the most significant results to evaluate porosity, mechanical characteristics and degree of saturation of various concretes, are developed. The consistency of the results of the measurements is analysed. The advantages and drawbacks of each technique are discussed

Fault-Tolerant and Dynamic Service Discovery System

Délivrabl

Procalcitonin and C-Reactive Protein for Bacterial Infection Diagnosis in Elderly Patients After Traumatic Orthopedic Surgery

International audienceBackground: Biomarkers prove valuable for diagnosing post-operative bacterial infection, but data in elderly patients is scarce. Here we analyze how procalcitonin and C-reactive protein (CRP) perform for bacterial infection diagnosis after traumatic orthopedic surgery in elderly patients.Methods: We included all patients admitted to our perioperative geriatrics unit after traumatic orthopedic surgery. Patients on antibiotics, presenting preoperative bacterial infection, or without procalcitonin measurement were excluded. Clinical and biological data were collected prospectively. Medical charts were reviewed by 3 experts blinded to biomarker results to assess bacterial infection diagnosis. Areas under the curve (AUC) and 90%-specificity thresholds were analyzed for baseline procalcitonin and CRP levels and relative variations.Results: Analysis included 229 patients (median age 86 years, hip fracture 83%), of which 40 had bacterial infection (pneumonia [n=23], urinary tract infection [n=8]; median delay to onset: two days post-admission). For bacterial infection diagnosis, the computed AUCs were not significantly different (procalcitonin-baseline 0.64 [95%CI 0.57-0.70]; procalcitonin-relative variation 0.65 [0.59-0.71]; CRP-baseline 0.68 [0.61-0.74]; CRP-relative variation 0.70 [0.64-0.76]). The 90%-specificity thresholds were 0.75 µg/L for procalcitonin-baseline, +62% for procalcitonin-variation, 222 mg/L for CRP-baseline, +111% for CRP-variation.Conclusions: Diagnostic performances of procalcitonin and CRP were not significantly different. Baseline levels and relative variations of these biomarkers showed little diagnostic value after traumatic orthopedic surgery in elderly patients