Spatial quantile predictions for elliptical random fields

International audienceIn this work, we consider elliptical random fields. We propose some spatial quantile predictions at one site given observations at some other locations. To this aim, we first give exact expressions for conditional quantiles, and discuss problems that occur for computing these values. A first affine regression quantile predictor is detailed, an explicit formula is obtained, and its distribution is given. Direct simple expressions are derived for some particular elliptical random fields. The performance of this regression quantile is shown to be very poor for extremal quantile levels, so that a second predictor is proposed. We prove that this new extremal prediction is asymptotically equivalent to the true conditional quantile. Through numerical illustrations, the study shows that Quantile Regression may perform poorly when one leaves the usual Gaussian random field setting, justifying the use of proposed extremal quantile predictions

Parametric information geometry with the package Geomstats

We introduce the information geometry module of the Python package Geomstats. The module first implements Fisher-Rao Riemannian manifolds of widely used parametric families of probability distributions, such as normal, gamma, beta, Dirichlet distributions, and more. The module further gives the Fisher-Rao Riemannian geometry of any parametric family of distributions of interest, given a parameterized probability density function as input. The implemented Riemannian geometry tools allow users to compare, average, interpolate between distributions inside a given family. Importantly, such capabilities open the door to statistics and machine learning on probability distributions. We present the object-oriented implementation of the module along with illustrative examples and show how it can be used to perform learning on manifolds of parametric probability distributions

Density hardening plasticity and mechanical aging of silica glass under pressure: A Raman spectroscopic study

In addition of a flow, plastic deformation of structural glasses (in particular amorphous silica) is characterized by a permanent densification. Raman spectroscopic estimators are shown to give a full account of the plastic behavior of silica under pressure. While the permanent densification of silica has been widely discussed in terms of amorphous-amorphous transition, from a plasticity point of view, the evolution of the residual densification with the maximum pressure of a pressure cycle can be discussed as a density hardening phenomenon. In the framework of such a mechanical aging effect, we propose that the glass structure could be labelled by the maximum pressure experienced by the glass and that the saturation of densification could be associated with the densest packing of tetrahedra only linked by their vertices

Síntesis de controladores difusos microprogramados

En este artículo se describe un método de síntesis de controladores difusos basado en una arquitectura predeterminada y parametrizada, y en un conjunto de herramientas informáticas. El resultado de la síntesis es un circuito compuesto de bloques aptos para ser descritos en VHDL, a nivel de transferencias entre registros, y de macrocélulas compilables.Eje: Procesamiento distribuido y paralelo. Tratamiento de señalesRed de Universidades con Carreras en Informática (RedUNCI

Síntesis de controladores difusos microprogramados

En este artículo se describe un método de síntesis de controladores difusos basado en una arquitectura predeterminada y parametrizada, y en un conjunto de herramientas informáticas. El resultado de la síntesis es un circuito compuesto de bloques aptos para ser descritos en VHDL, a nivel de transferencias entre registros, y de macrocélulas compilables.Eje: Procesamiento distribuido y paralelo. Tratamiento de señalesRed de Universidades con Carreras en Informática (RedUNCI

Computed Analysis of Three-Dimensional Cone-Beam Computed Tomography Angiography for Determination of Tumor-Feeding Vessels During Chemoembolization of Liver Tumor: A Pilot Study

The purpose of this study was to evaluate computed analysis of three-dimensional (3D) cone-beam computed tomography angiography (CTA) of the liver for determination of subsegmental tumor-feeding vessels (FVs). Eighteen consecutive patients underwent transarterial chemoembolization (TACE) from January to October 2008 for 25 liver tumors (15 hepatocellular carcinomas [HCCs] and 10 neuroendocrine metastases). Anteroposterior projection angiogram (two-dimensional [2D]) and 3D cone-beam CTA images were acquired by injection of the common hepatic artery. Retrospectively, FVs were independently identified by three radiology technologists using a software package (S) that automatically determines FVs by analysis of 3D images. Subsequently, three interventional radiologists (IRs) independently identified FVs by reviewing the 2D images followed by examination of the 3D images. Finally, the “ground truth” for the number and location of FVs was obtained by consensus among the IRs, who were allowed to use any imaging―including 2D, 3D, and all oblique or selective angiograms―for such determination. Sensitivities, durations, and degrees of agreement for review of 2D, 3D, and S results were evaluated. Sensitivity of 3D (73%) was higher than 2D (64%) images for identification of FVs (P = 0.036). The sensitivity of S (93%) was higher than 2D (P = 0.02) and 3D (P = 0.005) imaging. The duration for review of 3D imaging was longer than that for 2D imaging (187 vs. 94 s, P = 0.0001) or for S (135 s, P = 0.0001). The degree of agreement between the IRs using 2D and 3D imaging were 54% and 62%, respectively, whereas it was 82% between the three radiology technologists using S. These preliminary data show that computed determination of FVs is both accurate and sensitive

Relationship between in-shoe pressure measurements and fear of falling among noncommunity- dwelling elderly: a pilot study

Objectives: To investigate the relationship between fear of falling indicators and pedobarographic variables among non-communitydwelling elderly. Methods: Twenty-seven volunteers were recruited and assigned to three groups according to their level of fear of falling estimated using the Short FES-I score. The in-shoe foot pressure data were collected while walking 10 meters. The relative peak and mean force in different foot regions, functional gait tasks feature, and center of pressure displacement were measured. A Kruskal- Wallis test was performed to assess the differences between groups. Results: The anterior-posterior displacement of pressure center was significantly different across the groups during weight acceptance and single limb advancement phases. The different pressure regions showed significant differences in relative mean (p=0.006) and peak forces (p=0.004) in hindfoot. The relative peak force was different for a hallux (p=0.042), a first metatarsal head (p=0.026), and a hindfoot (p=0.038). Conclusions: In-shoe pressure measurement while walking may be important when assessing the risk and the fear of falling among elderly

Procédé pour conférer un caractère hydrophobe à une matière solide cellulosique ou amylacée

L'invention concerne un procédé pour conférer un caractère hydrophobe à une matière solide cellulosique ou amylacée, du type dans lequel on greffe un corps gras sur les fonctions alcool de la matière cellulosique ou amylacée. Selon l'invention, on réalise le greffage (a) en mettant la matière cellulosique ou amylacée en suspension dans une phase liquide composée d'un acide gras ou d'un ester d'acide gras, (b) en agitant le milieu hétérogène en présence d'un catalyseur basique pour réaliser une mise en contact des phases, (c) et en soumettant le milieu hétérogène à une irradiation micro-ondes de façon à le porter à une température comprise entre 150 DEG C et 210 DEG C pendant une durée comprise entre 30 secondes et 30 minutes. Le procédé de l'invention permet de rendre hydrophobe une matière cellulosique ou amylacée sans utilisation de solvants toxiques

Thermal ablation of ultrasound and non-contrast computed tomography invisible primary and secondary liver tumors: targeting by selective intra-arterial lipiodol injection

PURPOSETo evaluate the technical feasibility and outcomes of thermal ablation following selective intra-arterial lipiodol injection (SIALI) for targeting primary and secondary liver tumors invisible on ultrasound (US) and non-contrast computed tomography (CT).METHODSThis retrospective study included 18 patients with 20 tumors (67% male, mean age 60.8 ± 12.1 years). The 20 tumors included 15 liver metastases and 5 hepatocellular carcinomas. All patients underwent single-session SIALI and subsequent CT-guided thermal ablation. The primary outcome was a technical success, defined as visualization of the tumor after SIALI and successful thermal ablation. Secondary outcomes were local recurrence rate and procedure-related complications.RESULTSThe median tumor size was 1.5 (1–2.5) cm. In addition, SIALI was performed with a median volume of 3 (1–10) mL of lipiodol resulting in intra-tumoral iodized oil accumulation in 19 tumors and negative imprint with iodized oil accumulation of the surrounding liver parenchyma in 1 tumor. The technical success rate was 100%. No local occurrence was observed at a mean follow-up time of 3 ± 2.5 years.CONCLUSIONSIALI to tag liver tumors not visible with US and non-contrast CT before percutaneous ablation is highly feasible and has a high success rate for the treatment of both primary and secondary liver tumors