Search results for " Transient"
showing 10 items of 191 documents
Regional cerebral blood flow (rCBF) changes following local brain compression in the cat.
1968
Antivitamin K Drugs in Stroke Prevention
2014
Among the different subtypes of ischaemic strokes, almost 20 % are of cardiac origin. Different are the causes of cardioembolic stroke, but the most common is the atrial fibrillation, a supraventricular arrhythmia. Appropriate use of antiplatelet drugs and anticoagulants after transient ischaemic attack (TIA) or ischaemic stroke depends on whether the underlying cause is cardioembolic or of presumed arterial origin. Adequate antiplatelet therapy is recommended for secondary prevention after cerebral ischaemia of presumed arterial origin, whether for patients with TIA and ischaemic stroke of cardiac origin, mainly due to atrial fibrillation. Vitamin K antagonists (VKAs) are highly effective …
Air pollution and stroke. A new modifiable risk factor is in the air
2019
Abstract Evidence from epidemiological studies has demonstrated that outdoor air pollution is now a well-known major problem of public health, mainly in low and middle income countries. Contrasting with myocardial infarction , there are few data on the association of air pollution and stroke. Methods We propose a narrative literature review of the effects and the underlying biological mechanisms of short- and long-term exposure to air pollutants on stroke risk and mortality, using the following key-words: stroke, cerebrovascular events, ischemic and haemorrhage stroke, transient ischaemic attack , mortality, air pollution and air pollutants. Results Twenty-one papers were selected. Air poll…
Single Event Transients and Pulse Quenching Effects in Bandgap Reference Topologies for Space Applications
2016
An architectural performance comparison of bandgap voltage reference variants, designed in a $0.18~\mu \text {m}$ CMOS process, is performed with respect to single event transients. These are commonly induced in microelectronics in the space radiation environment. Heavy ion tests (Silicon, Krypton, Xenon) are used to explore the analog single-event transients and have revealed pulse quenching mechanisms in analogue circuits. The different topologies are compared, in terms of cross-section, pulse duration and pulse amplitude. The measured results, and the explanations behind the findings, reveal important guidelines for designing analog integrated circuits, which are intended for space appli…
Population Properties of Compact Objects from the Second LIGO-Virgo Gravitational-Wave Transient Catalog
2021
Abbott, R., et al. (LIGO and Virgo Collaboration)
Search for Gravitational Waves Associated with Gamma-Ray Bursts Detected by Fermi and Swift during the LIGO-Virgo Run O3a
2022
Abbott, R., et al. (LIGO and VIRGO Collaboration)
Liver stiffness quantification in biopsy-proven nonalcoholic fatty liver disease patients using shear wave elastography in comparison with transient …
2021
Purpose: This study prospectively assessed the performance of liver stiffness measurements using point shear-wave elastography (p-SWE) in comparison with transient elastography (TE) in patients with biopsy-proven nonalcoholic fatty liver disease (NAFLD). Methods: Fifty-six consecutive adult patients with a histological diagnosis of NAFLD prospectively underwent TE and p-SWE on the same day. The median of 10 measurements (SWE-10), the first five (SWE-5), and the first three (SWE-3) measurements were analyzed for p-SWE. Liver biopsy was considered as the reference standard for liver fibrosis grade. Receiver operating characteristic (ROC) curves and areas under the ROC curves (AUROCs) were cal…
Partial Discharges in HVDC Cables - The Effect of the Temperature Gradient During Load Transients
2021
The paper investigates the role of the space charge accumulation phenomena in the inception of Partial Discharges (PD) in a defect within the bulk of the dielectrics of a High Voltage Direct Current (HVDC) cable. It is widespread accepted that the number of PD occurring in an HVDC cable during its lifetime is largely less than that under AC voltage stress. This is essentially due to higher values of the voltage between the conductor and the screen needed to trigger PD under a steady DC voltage than the same value under AC stress. Nevertheless, due to the dependency of the electrical conductivity of the insulation on the electric field and temperature, PD in HVDC cables is strongly influence…
Photocycle of point defects in highly- and weakly-germanium doped silica revealed by transient absorption measurements with femtosecond tunable pump.
2022
AbstractWe report pump-probe transient absorption measurements addressing the photocycle of the Germanium lone pair center (GLPC) point defect with an unprecedented time resolution. The GLPC is a model point defect with a simple and well-understood electronic structure, highly relevant for several applications. Therefore, a full explanation of its photocycle is fundamental to understand the relaxation mechanisms of such molecular-like systems in solid state. The experiment, carried out exciting the sample resonantly with the ultraviolet (UV) GLPC absorption band peaked at 5.1 eV, gave us the possibility to follow the defect excitation-relaxation dynamics from the femto-picosecond to the nan…
Flow and sediment transport process in vegetated beds: experimental investigation in laboratory flumes
2017
The uncertainty regarding the interpretation of sediment transport phenomena during the transients determines some limitations in mathematical modeling of scouring process. But, quantitative estimate of sediment transport processes is important, especially in river-control engineering and water management projects. To this aim, literature (among others Hoffmans and Booji, 1993; Chrisochoides et al., 2003) shows it is necessary to well predict the flow velocity field, the eddy-viscosity and the bed shear stress in order to make correct calculations in simulating the bed-load transport and the development of scour hole in time. Particularly, the role of turbulent structures, developing within…