Réduction du conditionnement pour les problèmes de discrétisation microlocale

Dans cet article, nous analysons les propriétés de conditionnement des systèmes linéaires venant de la discrétisation microlocale. Ces systèmes utilisent des fonctions de base localement oscillantes pour modéliser des problèmes de propagation d'onde en régime harmonique. Ces problèmes étant très mal conditionnés, nous proposons d'abord une analyse de la difficulté en terme de \emph{sur-discrétisation} ; celle-ci créant des ondes évanescentes. La première solution que nous regardons est de projeter le problème sur l'espace orthogonal à ces modes. Nous faisons cela sur un problème modèle mais ça n'est pas une solution satisfaisante pour des systèmes de taille importante. Nous proposons alors de transformer le système à l'aide d'une base d'ondelettes. Il apparaît que cette transformation différencie fortement les gros coefficients des petits. Ceci nous permet de réaliser un filtrage de la matrice transformée pour obtenir un système réduit qui est bien conditionné. Il s'agit ici d'un usage non classique des ondelettes puisqu'elles agissent dans le domaine spectral. Nous obtenons finalement une méthode qui n'utilise qu'un degré de liberté par longueur d'onde environ pour simuler des problèmes de diffraction

Canagliflozin and renal outcomes in type 2 diabetes and nephropathy

BACKGROUND Type 2 diabetes mellitus is the leading cause of kidney failure worldwide, but few effective long-term treatments are available. In cardiovascular trials of inhibitors of sodium–glucose cotransporter 2 (SGLT2), exploratory results have suggested that such drugs may improve renal outcomes in patients with type 2 diabetes. METHODS In this double-blind, randomized trial, we assigned patients with type 2 diabetes and albuminuric chronic kidney disease to receive canagliflozin, an oral SGLT2 inhibitor, at a dose of 100 mg daily or placebo. All the patients had an estimated glomerular filtration rate (GFR) of 30 to <90 ml per minute per 1.73 m2 of body-surface area and albuminuria (ratio of albumin [mg] to creatinine [g], >300 to 5000) and were treated with renin–angiotensin system blockade. The primary outcome was a composite of end-stage kidney disease (dialysis, transplantation, or a sustained estimated GFR of <15 ml per minute per 1.73 m2), a doubling of the serum creatinine level, or death from renal or cardiovascular causes. Prespecified secondary outcomes were tested hierarchically. RESULTS The trial was stopped early after a planned interim analysis on the recommendation of the data and safety monitoring committee. At that time, 4401 patients had undergone randomization, with a median follow-up of 2.62 years. The relative risk of the primary outcome was 30% lower in the canagliflozin group than in the placebo group, with event rates of 43.2 and 61.2 per 1000 patient-years, respectively (hazard ratio, 0.70; 95% confidence interval [CI], 0.59 to 0.82; P=0.00001). The relative risk of the renal-specific composite of end-stage kidney disease, a doubling of the creatinine level, or death from renal causes was lower by 34% (hazard ratio, 0.66; 95% CI, 0.53 to 0.81; P<0.001), and the relative risk of end-stage kidney disease was lower by 32% (hazard ratio, 0.68; 95% CI, 0.54 to 0.86; P=0.002). The canagliflozin group also had a lower risk of cardiovascular death, myocardial infarction, or stroke (hazard ratio, 0.80; 95% CI, 0.67 to 0.95; P=0.01) and hospitalization for heart failure (hazard ratio, 0.61; 95% CI, 0.47 to 0.80; P<0.001). There were no significant differences in rates of amputation or fracture. CONCLUSIONS In patients with type 2 diabetes and kidney disease, the risk of kidney failure and cardiovascular events was lower in the canagliflozin group than in the placebo group at a median follow-up of 2.62 years

Résolution hautes fréquence d'équations intégrales par une méthode de discrétisation microlocale

Ce travail a consisté en la présentation et la validation d'une nouvelle méthode ayant pour thème la simulation de la propagation d'ondes. Le problème analysé est celui de la diffraction d'ondes en régime harmonique par des obstacles tridimensionnels quelconques. Pour modéliser ces phénomènes, nous nous sommes intéressés aux équations intégrales. La méthodes proposée a pour objectif de les utiliser à hautes fréquences en réduisant la complexité du calcul et surtout en stockage mémoire. Son originalité réside en une approche en deux temps de la solution cherchée. Dans un premier temps, on utilise une discrétisation microlocale. Dans un second temps, on propose une transformation par ondelettes. L'approche microlocale, qui repose sur l'usage systèmatique d'une localisation en espace et en direction de propagation, conduit à inverser des matrices creuses mais très mal conditionnées. Pour surmonter cette difficulté, nous aovns considéré la seconde approche qui consiste à opérer un filtrage par ondelettes. Ces approximations se sont avérées particulièrement efficaces pour diminuer le remplissage et la taille des matrices issues de la résolutions d'équations intégrales.Le développement et la mise au point d'un code ont été effectués au CERMICS-INRIA Sophia-Antipolis. La vérification de la validité de notre code s'appuie sur des calculs de surface équivalente radar. Des résultats numériques encourageants sont présentés pour des obstacles convexes et non-connexes.La méthode est ensuite étendue aux opérateurs pseudo-différentiels et Fourier-intégraux. Ils interviennent dans le cas de milieux hétérogènes et anisotropes

The Relationship between Philippine Population, Remittances, Foreign Direct Investment, and Trade Openness on its Gross Domestic Product

The Philippine economy is regarded as one of the leading emerging markets, although many issues remain unsettled. The country experienced ups and downs in its economic growth through different administrations and policies that affected its various determinants. In the past decades, the Philippines has focused on changing the country’s economic standing. Policymakers and researchers are interested in improving the country’s economic performance by identifying leading driving forces. This study will analyze the relationship between Population, Remittances, Foreign Direct Investment, and Trade Openness on Gross Domestic Product. It would specifically investigate the nature of the relationship between the variables to guide policymakers in prioritizing indicators that would generate the most growth. This paper aims to understand these relationships in the Philippine context from 2005-2020. The results of the adjusted regression model show that GDP has a relationship with TO and Remittances, which rejects the null hypothesis. Remittances accept the null hypothesis, making it an insignificant variable in the model. It also shows that FDI positively correlates with GDP, while Population and TO affect GDP negatively. In the four assumptions mentioned in the methodologies, only one stayed true in the variables used in a Philippine setting: As remittances increase, GDP also increases. Furthermore, these observations confirm that Population and TO affect the economic growth of the Philippines negatively. The researchers recommend that the Philippine government create policies to improve the FDI attractiveness of the Philippines, encourage employment for OFWs, and create more economic opportunities for the growing population

Direct in-depth determination of a complex magnetic configuration in an exchange-coupled bilayer with perpendicular and in-plane anisotropy

International audienc

Structure, morphology and magnetism of an ultra-thin [NiO/CoO]/PtCo bilayer with perpendicular exchange bias

International audienceElectronic and magnetic properties of nanoscale materials are closely related to the atomic arrangement at the interface shared by different chemical elements. A very precise knowledge of the surface/interface structure is then essential to properly interpret the new properties coming out. Of a particular interest is the relationship between structure, morphology and magnetic properties of exchanged-coupled interfaces in ferromagnetic (FM) and antiferromagnetic (AF) materials. The interaction at the AF/FM interface modifies the magnetic switching properties of the FM film, which turn out to be a usefull property on new magnetic devices technology. We present here an investigation of the buried exchange-coupled interface [NiO/CoO]/[PtCo] grown on a Pt(111) single crystal. The magneto-optical Kerr effect reveals a strong coupling at the interface, by an increasing coercivity, and a spin reorientation of the FM film when ordering occurs in the AF layer. The combination of grazing incidence X-ray diffraction, X-ray reflectivity and soft X-ray resonant magnetic scattering yields a comprehensive description of the system

Depth Magnetization Profile of a Perpendicular Exchange Coupled System by Soft-X-Ray Resonant Magnetic Reflectivity

The magnetic profile across the interface of a perpendicular exchange coupled [NiO/CoO]3/Pt-Co/ Pt(111) system is investigated. The magneto-optic Kerr effect reveals a strong coupling between the antiferromagnetic (AFM) oxide and the ferromagnetic (FM) Pt-Co layer, by an increasing coercivity and a rotation of the easy magnetization axis of the FM layer along the AFM spins. Soft x-ray resonant magnetic reflectivity is used to probe the spatial distribution of the out-of-plane magnetization inside the oxide above its ordering temperature. It extends over 1 nm and exhibits a change of sign