Influence of model errors on some spatial analysis methods

The purpose of this article is ta study the influence of model errors on the performances of some spatial analysis methods. We present a unification of both the concerned methods and perturbations . This leads to a general expression of the estimation error on the sources bearings as a functon of both the perturbation and the method. This expression, calculated at the first order and in the non-asymptotic case, is then derived for each method and each perturbation .Nous étudions dans cet article l'influence d'erreurs de modèle sur le performances de certaines méthodes d'analyse spatiale. Une unification de methodes ainsi que des perturbations considérés nous permet de donner une formule générale pour l'erreur d'estimation des directions d'arrivées, en fonction de la perturbation et de la méthode utilisée. Cette formule, obtenue au premier ordre et dans le cas non-asymptotique, est ensuite dérivée pour chaque méthode et pour chaque perturbatio

Comparison of both the propagator and the Weiss-Friedlander methods

The purpose of this article is to compare two methods for the self-calibration of a distorted array. These methods allow to estimate both the array shape and the bearing angles. The first one uses the properties of the propagator The second one uses successive projections, on the bearing angles subspace and then on the array geometrical parameters subspace ; it is based on the MD-Music algorithm . We take a particular interest in the validity domains and in the limitations of both methods.Nous comparons dans cet article deux methodes pour l'auto-calibration d'une antenne déformée. Il s'agit de deux méthodes qui permettent d'estimer conjointement la forme de l'antenne et les directions d'arrivée des fronts d'ondes. La première utilise les propriétés du propagateur. La seconde utilise des projections successives tantôt sur le sous-espace des directions d'arrivées, tantôt sur le sous-espace des paramètres géométriques de l'antenne; elle repose sur l'algorithme MD-Music. Nous méttons notamment en évidence les domaines d'application et les limitations de ces deux méthode

Diagnosis of economic and financial risks in the enterprises activity

Polymer electrolytes containing poly(ethylene imine) (PEI) and lithium bis(trifluoromethylsulfonyl) imide (LiTFSI) can serve as model electrolytes for electrochromic devices. Such electrolytes were characterized by differential scanning calorimetry, conductivity, and viscosity measurements. The glass transition temperature (T-g) and viscosity of the PEI-LiTESI electrolytes have minima at a [N]:[Li] ratio of 100:1. Both T-g and viscosity increased at high salt concentrations. The temperature dependences of ionic conductivity and viscosity followed an Arrhenius equation with parameters depending only weakly on the salt concentration. The fluid behavior of the electrolytes could be reconciled with the Bingham plastic model with parameters being functions of salt concentration

Editorial: Engineered Nanoporous Materials for Chemical Sensors and Biosensors

Abstract not availableAbel Santos, Lluis F. Marsal and Tushar Kumeri

Autofluorescence of stingray skeletal cartilage: hyperspectral imaging as a tool for histological characterization

Tessellated cartilage is a distinctive composite tissue forming the bulk of the skeleton of cartilaginous fishes (e.g. sharks and rays), built from unmineralized cartilage covered at the surface by a thin layer of mineralized tiles called tesserae. The finescale structure and composition of elasmobranch tessellated cartilage has largely been investigated with electron microscopy, micro-computed tomography and histology, but many aspects of tissue structure and composition remain uncharacterized. In our study, we demonstrate that the tessellated cartilage of a stingray exhibits a strong and diverse autofluorescence, a native property of the tissue which can be harnessed as an effective label-free imaging technique. The autofluorescence signal was excited using a broad range of wavelengths in confocal and light sheet microscopy, comparing several sample preparations (fresh; demineralized and paraffin-embedded; non-demineralized and plastic-embedded) and imaging the tissue at different scales. Autofluorescence varied with sample preparation with the signal in both plastic- and paraffin-embedded samples strong enough to allow visualization of finescale (≥ 1 μm) cellular and matrix structures, such as cell nuclei and current and former mineralization fronts, identifiable by globular mineralized tissue. A defined pericellular matrix (PCM) surrounding chondrocytes was also discernible, described here for the first time in elasmobranchs. The presence of a PCM suggests similarities with mammalian cartilage regarding how chondrocytes interact with their environment, the PCM in mammals acting as a transducer for biomechanical and biochemical signals. A posterior analysis of hyperspectral images by an MCR-ALS unmixing algorithm allowed identification of several distinct fluorescence signatures associated to specific regions in the tissue. Some fluorescence signatures identified could be correlated with collagen type II, the most abundant structural molecule of cartilage. Other fluorescence signatures, however, remained unidentified, spotlighting tissue regions that deserve deeper characterization and suggesting the presence of molecules still unidentified in elasmobranch skeletal cartilage. Our results show that autofluorescence can be a powerful exploratory imaging tool for characterizing less-studied skeletal tissues, such as tessellated cartilage. The images obtained are largely comparable with more commonly used techniques, but without the need for complicated sample preparations or external staining reagents standard in histology and electron microscopy (TEM, SEM)

New Development in the core yarns manufacture

A new mechanism for the regulation of feeding tension of elastic filaments has been developed, in cooperation with a reputable manufacturer of textile machinery, to obtain “core spun” yarns. This device reduces, of a very significant form, the coefficient of variation of the elongation of the yarn and, consequently, the fabrics obtained with this yarns are more regular appearance. This mechanism is fundamental when the new spools of T-400, with diameter and weight superiors to the standard size, are processed.Postprint (published version

ISUOG Safety Committee updated recommendation on use of respirators by practitioners undertaking obstetric and gynecological ultrasound in context of SARS-CoV-2 Omicron variant of concern

status: publishe

Engineering of hybrid nanoporous anodic alumina photonic crystals by heterogeneous pulse anodization

In this study, we present an advanced nanofabrication approach, so-called ‘heterogeneous pulse anodization’ (HPA), in which galvanostatic stepwise and apodized sinusoidal pulse anodizations are combined in a single process. This novel anodization method enables the precise optical engineering of the characteristic photonic stopbands (PSBs) of nanoporous anodic alumina photonic crystals (NAA-PCs). The resulting structures are hybrid PCs (Hy-NAA-PCs) composed of distributed Bragg reflectors (DBRs) and apodized gradient-index filters (APO-GIFs) embedded within the same PC structure. The modification of various anodization parameters such as anodization period, relative and total anodization time, structural arrangement of PCs within Hy-NAA-PCs, and pore widening time allows the fine-tuning of the PSBs’ features (i.e. number, position and bandwidth of central wavelength) across the spectral regions. The effects of these fabrication parameters are systematically assessed, revealing that the positions of the characteristic transmission bands of Hy-NAA-PCs are highly controllable. Our study provides a comprehensive rationale towards the development of unique Hy-NAA-PCs with controllable optical properties, which could open new opportunities for a plethora of applications.Siew Yee Lim, Cheryl Suwen Law, Lluis F. Marsal and Abel Santo