Search results for " attenuation"
showing 10 items of 65 documents
Diagnostic accuracy of non-invasive tests for advanced fibrosis in patients with NAFLD : an individual patient data meta-analysis
2021
ObjectiveLiver biopsy is still needed for fibrosis staging in many patients with non-alcoholic fatty liver disease. The aims of this study were to evaluate the individual diagnostic performance of liver stiffness measurement by vibration controlled transient elastography (LSM-VCTE), Fibrosis-4 Index (FIB-4) and NAFLD (non-alcoholic fatty liver disease) Fibrosis Score (NFS) and to derive diagnostic strategies that could reduce the need for liver biopsies.DesignIndividual patient data meta-analysis of studies evaluating LSM-VCTE against liver histology was conducted. FIB-4 and NFS were computed where possible. Sensitivity, specificity and area under the receiver operating curve (AUROC) were c…
Prevalence, predictors, and severity of lean nonalcoholic fatty liver disease in patients living with human immunodeficiency virus
2020
Abstract Background The burden of nonalcoholic fatty liver disease (NAFLD) is growing in people living with human immunodeficiency virus (HIV). NAFLD is associated with obesity; however, it can occur in normoweight (lean) patients. We aimed to investigate lean NAFLD in patients living with HIV. Methods We included patients living with HIV mono-infection from 3 prospective cohorts. NAFLD was diagnosed by transient elastography (TE) and defined as controlled attenuation parameter ≥248 dB/m, in absence of alcohol abuse. Lean NAFLD was defined when a body mass index was <25 kg/m2. Significant liver fibrosis was defined as TE ≥7.1 kPa. The presence of diabetes, hypertension, or hyperlipid…
Statistical Analysis of Macroseismic Data for a better Evaluation of Earthquakes Attenuation Laws
2020
In this work we propose a statistical approach, based on the joint analysis of macroseismic data of Italian seismic events of the last two centuries, with which we obtain simultaneously maximum likelihood estimates of attenuation laws and coordinates of hypocenters. Our first results encourage us to use in the future more complex models, with a larger number of historical earthquakes.
Controlled attenuation parameter and alcoholic hepatic steatosis: Diagnostic accuracy and role of alcohol detoxification.
2018
Background & Aims: Controlled attenuation parameter (CAP) is a novel non-invasive measure of hepatic steatosis, but it has not been evaluated in alcoholic liver disease. Therefore, we aimed to validate CAP for the assessment of biopsy-verified alcoholic steatosis and to study the effect of alcohol detoxification on CAP. Methods: This was a cross-sectional biopsy-controlled diagnostic study in four European liver centres. Consecutive alcohol-overusing patients underwent concomitant CAP, regular ultrasound, and liver biopsy. In addition, we measured CAP before and after admission for detoxification in a separate single-centre cohort. Results: A total of 562 patients were included in the s…
Genetic determinants of heel bone properties: genome-wide association meta-analysis and replication in the GEFOS/GENOMOS consortium
2014
Quantitative ultrasound of the heel captures heel bone properties that independently predict fracture risk and, with bone mineral density (BMD) assessed by X-ray (DXA), may be convenient alternatives for evaluating osteoporosis and fracture risk. We performed a meta-analysis of genome-wide association (GWA) studies to assess the genetic determinants of heel broadband ultrasound attenuation (BUA; n = 14 260), velocity of sound (VOS; n = 15 514) and BMD (n = 4566) in 13 discovery cohorts. Independent replication involved seven cohorts with GWA data (in silico n = 11 452) and new genotyping in 15 cohorts (de novo n = 24 902). In combined random effects, meta-analysis of the discovery and repli…
Can loss of sensory attenuation be accurately demonstrated using two effectors simultaneously?
2015
Sir, Recently, Parees and colleagues (2014) compared patients with functional (psychogenic) movement disorders and healthy subjects who were asked to match a force delivered to their left finger by pressing on it directly, or by operating a joystick to press down on it, with the other hand. They observed that healthy subjects generated more force than required when pressing directly on their finger (compared with using the joystick), whereas patients did not. They interpreted and discussed this result as a loss of sensory attenuation that typically occurs in healthy subjects during self-generated movements and suggested by return, that it illustrates an altered sense of agency for the patie…
Application of low intensity ultrasonics to cheese manufacturing processes.
2002
Ultrasound has been used to non-destructively assess the quality of many foods such as meat, fish, vegetables and dairy products. This paper addresses the applications of low intensity ultrasonics in the cheese manufacturing processes and highlights the areas where ultrasonics could be successfully implemented in the future. The decrease of ultrasonic attenuation during the renneting process can be used to determine the optimum cut time for cheese making. The ultrasonic velocity increases during maturation for those types of cheese that become harder during this manufacturing stage, thus being an indicator of the maturity degree. Moreover, ultrasonic measurements could be linked to sensory …
Measurement of the velocity and attenuation of fourth sound in helium II
1979
The velocity and the attenuation of fourth sound have been measured in liquid helium at temperatures between 0.8 K and the λ point, along the vapor pressure curve. The measurements were made using the resonance technique and the helium was contained between small pores in packed powder specimens. From the velocity, it could be determined that the sound propagates under “adiabatic” conditions. According to theory, the attenuation of fourth sound consists of two contributions: surface losses due to heat exchange with the resonator body and volume losses due to dissipative processes associated with the viscosity coefficients η and ζ3. The results of our attenuation measurements are in agreemen…
Overview of radiation induced point defects in silica-based optical fibers
2019
International audience; Silica-based optical fibers, fiber-based devices and optical fiber sensors are today integrated in a variety of harsh environments associated with radiation constraints. Under irradiation, the macroscopic properties of the optical fibers are modified through three main basic mechanisms: the radiation induced attenuation, the radiation induced emission and the radiation induced refractive index change. Depending on the fiber profile of use, these phenomena differently contribute to the degradation of the fiber performances and then have to be either mitigated for radiation tolerant systems or exploited to design radiation detectors and dosimeters. Considering the stro…
The Fatty Liver Assessment in Germany (FLAG) cohort study identifies large heterogeneity in NAFLD care
2020
Background & Aims NAFLD is a growing health concern. The aim of the Fatty Liver Assessment in Germany (FLAG) study was to assess disease burden and provide data on the standard of care from secondary care. Methods The FLAG study is an observational real-world study in patients with NAFLD enrolled at 13 centres across Germany. Severity of disease was assessed by non-invasive surrogate scores and data recorded at baseline and 12 months. Results In this study, 507 patients (mean age 53 years; 47% women) were enrolled. According to fibrosis-4 index, 64%, 26%, and 10% of the patients had no significant fibrosis, indeterminate stage, and advanced fibrosis, respectively. Patients with advanced fib…