Search results for "DOPPLER"

Tomography of the SN 1987A ejecta and AGN core-shifts with high-precision astrometry

2017

Esta tesis trata dos temas muy distintos: (1) el estudio de las estructuras y movimientos propios de los chorros de los núcleos activos de galaxias (AGN) que componen la muestra S5 del casquete polar, por medio de astrometría global de alta precisión con la técnica de interferometría de muy larga base (VLBI); y (2) la reconstrucción tomográfica (i.e., 3D) de la emisión molecular de la parte interna de la supernova SN 1987A y su comparación con modelos de explosión de supernovas. En la primera parte, presentamos el análisis astrométrico diferencial llevado a cabo para todas las fuentes de la muestra S5 del casquete polar. Se consigue aplicar por primera vez a 43 GHz la técnica de astrometría…

A range of pulses commonly used for human transcranial ultrasound stimulation are clearly audible.

2021

The effects of optimizing blood inflow in the pedicle on perforator flap survival: A pilot study in a rat model

2020

Background Perforator flaps have led to a revolution in reconstructive surgery by reducing donor site morbidity. However, many surgeons have witnessed partial flap necrosis. Experimental methods to increase inflow have relied on adding a separate pedicle to the flap. The aim of our study was to experimentally determine whether increasing blood flow in the perforator pedicle itself could benefit flap survival. Methods In 30 male Lewis rats, an extended posterior thigh perforator flap was elevated and the pedicle was dissected to its origin from the femoral vessels. The rats were assigned to three groups: control (group I), acute inflow (group II) and arterial preconditioning (group III) dep…

Non-invasive determination of cardiac output by transesophageal Doppler ultrasound-clinical application and validation

2003

The authors describe the development and validation of a device using transesophageal (TE) Doppler ultrasound to provide continuous and noninvasive monitoring of cardiac output (CO) and related parameters. In intubated and artificially ventilated patients who underwent pulmonary artery catherization for hemodynamic monitoring, CO was determined by the esophageal Doppler ultrasound probe and compared to the results obtained simultaneously by means of thermodilution. A very close correlation was found between the results (r=0.99), with a standard estimate of error less than 5% as well as good reproducibility (r=0.96 and r=0.98). >

A non-stationary one-ring scattering model

2013

This paper introduces a non-stationary one-ring scattering model in which the mobile station (MS) can move along a straight line from the ring's center to the border of the ring. This movement results in a time-variant angle-of-arrival (AOA), which is modeled by a stochastic process. We derive the first-order density of the AOA process in closed form. Subsequently, a closed-form expression is provided for the local power spectral density (PSD) of the channel. We also formulate the local autocorrelation function (ACF) of the complex channel gain in integral form, from which a highly accurate closed-form approximation is derived. Furthermore, the average Doppler shift and the Doppler spread o…

Severity of Asymptomatic Carotid Stenosis and Risk of Ipsilateral Hemispheric Ischaemic Events: Results from the ACSRS Study

2005

Objectives. This study determines the risk of ipsilateral ischaemic neurological events in relation to the degree of asymptomatic carotid stenosis and other risk factors. Methods. Patients (n = 1115) with asymptomatic internal carotid artery (ICA) stenosis greater than 50% in relation to the bulb diameter were followed up for a period of 6-84 (mean 37.1) months. Stenosis was graded using duplex, and clinical and biochemical risk factors were recorded. Results. The relationship between ICA stenosis and event rate is linear when stenosis is expressed by the ECST method, but S-shaped if expressed by the NASCET method. In addition to the ECST grade of stenosis (RR 1.6; 95% CI 1.21-2.15), histor…

Ultrafast optics in coherently spinning molecules

2020

This thesis reports on the study of unidirectional rotation of molecules and focuses on the rotational Doppler effect occuring in the course of third-harmonic generation in coherently spinning molecules.The rotational Doppler effect appears when a circularly polarized wave interacts with an anisotropic rotating object. During the interaction, an exchange of angular momentum and energy between the field and the object occurs, leading to a frequency shift of the wave. In this work, the frequency shift of the third-harmonic generated in unidirectionaly rotating molecules has been observed. An anlytical model developped in the mansucript forsees four kinds of frequency shifts depending on the m…

RUOLO DELL’ECOCOLOR DOPPLER TISSUTALE NELLA VALUTAZIONE DELLA CARDIOTOSSICITÀ DA CHEMIOTERAPICI

2010

R E L A Z I O N I T R A I N D I C E  D I R E S I S T E N Z A I N T R A PA R E N C H I M A L E R E N A L E E D E N S I TA’ VA S C O L A R E R E T I N …

2022

MONITORAGGIO ECO-COLORDOPPLER DEL RENE TRAPIANTATO.NOSTRA ESPERIENZA

2005

Introduzione: La metodica ultrasonografica, come è noto, scevra da complicanze, ripetibile, non invasiva ed altamente tollerata dal paziente, consente un attento monitoraggio sia delle caratteristiche anatomomorfologiche del graft (ATN,rigetto,intossicazione da farmaci,infarto),sia l’immediata diagnosi di complicanze post-operatorie (raccolte fluide perirenali, idronefrosi,trombosi vascolari).L’integrazione con power-colordoppler consente altresì il corretto monitoraggio delle condizioni di perfusione d’organo, desunte dai dati connessi alla valutazione seriata delle resistenze parenchimali. Materiali e metodi: La casistica è limitata agli ultimi tre anni di attività su un gruppo di 22 pazi…