Search results for "doppler"
showing 10 items of 637 documents
A Comprehensive Ultrasonographic Assessment of Pediatric and Adolescent Varicocele Can Improve Surgical Results.
2020
<b><i>Purpose:</i></b> Undetected refluxing venous systems could cause persistence/recurrence of varicoceles in patients undergoing varicocelectomy. Color Doppler ultrasound (CDUS) is an important tool in the diagnosis and follow-up of varicocele, and could be successfully used to detect a venous reflux in the iliac-deferential district, usually involved in the recurrence/persistence of varicocele. <b><i>Materials and Methods:</i></b> We compared 2 historical series of patients treated with Palomo laparoscopic varicocelectomy between 1994 and 2018. In group 1, preoperative scrotal CDUS was obtained, while in group 2, additional inguinal CDUS w…
Robust Communications for the Underwater Internet of Things
2023
In recent years, the emergence of numerous applications and activities involving the underwater world have given rise to a new class of technologies that takes the name of Internet of Underwater Things (IoUT). Submarine activities such as remote control, pollution monitoring, data collection, disaster detection or even early warning and assisted navigation are just some of the main applications that require the use of underwater communication systems capable of providing connectivity between static and mobile nodes deployed at different depths. Generally, underwater communications employ audio signals which can propagate relatively far but are also significantly affected by Doppler distorti…
Qualitative and quantitative evaluation of solitary thyroid nodules with contrast-enhanced ultrasound: initial results
2005
To assess the feasibility of contrast-enhanced ultrasound (CEUS) of the thyroid gland and to evaluate the potential of this method for characterising solitary thyroid nodules.18 patients affected by solitary thyroid nodules (size range: 0.6 to 3.6 cm; mean: 1.8 cm) confirmed by surgery (nine papillary carcinomas, four follicular carcinomas, three hyperplasias, one follicular adenoma and one Plummer’s adenoma) underwent pulse inversion US at low M.I. (0.06 to 0.08) after i.v. injection of a 2.4-mL bolus of SonoVue. Baseline echogenicity and the dynamic enhancement pattern of each nodule, in comparison with adjacent thyroid parenchyma, were assessed. Signal intensity values on grey-scale imag…
Analysing longitudinal turbulence intensity in vegetated channels
2007
Vegetation altering hydrodynamic conditions of an open channel flow controls the exchanges of sediment, nutrients and contaminants. In this paper the turbulence structure of open-channel flow over a flexible grass vegetation is investigated. Velocity measurements were carried out, in a rectangular flume, using a 2D-ADV (Acoustic Doppler Velocimeter) for different values of stem concentration, water discharge, and bed slope. The experimental results showed that: 1) the maximum value of the longitudinal turbulence intensity occurs at a water depth close to the bent vegetation height; 2) the turbulence intensity damps for increasing values of the stem concentration; 3) above the vegetation hei…
Utilidad del color doppler, power doppler y el contraste sonográfico en el diagnóstico por imagen del cáncer de próstata localizado
2012
Objetivos: 1º. Estudiar el rendimiento diagnóstico de la ecografía transrectal en escala de grises, power doppler y del contraste sonográfico en el diagnóstico precoz por imagen del cáncer de próstata localizado. 2º. Comparar la rentabilidad diagnóstica de la biopsia prostática aleatoria con la biopsia ecodirigida mediante power doppler y contraste sonográfico, en el diagnóstico precoz por imagen del cáncer de próstata localizado. Material y métodos: Se diseñó un estudio epidemiológico prospectivo y transversal de ámbito provincial, para estudiar el rendimiento diagnóstico de la ecografía transrectal en escala de grises (EG), Power Doppler (PD) y del contraste sonográfico (CS) en el diagnós…
A combination of umbilical artery PI and normalized blood flow volume in the umbilical vein: Venous–arterial index for the prediction of fetal outcome
2008
Abstract Objective The objective was to assess the diagnostic power of the umbilical venous–arterial index (VAI) as a combination of the pulsatility index in the umbilical artery and the normalized blood flow volume in the umbilical vein for the prediction of poor fetal outcome. Study design This was a prospective clinical study in which the umbilical artery PI (UAPI), the normalized umbilical vein blood volume flow rate ( n UV; ml/min/kg estimated fetal body weight), the venous–arterial index (VAI; n UV/UAPI), and the pulsatility index (PI) in the umbilical artery (UA), uterine artery (utA), middle cerebral artery (MCA), and aorta were determined in 181 fetuses once (at between 17 and 41 w…
Performance Analysis of Sweep-Spread Carrier (S2C) Modulation for Underwater Communications
2022
In the last decades, underwater acoustic communications have seen a growing development with a variety of research as well as commercial applications, dealing with channel distortions, multipath and Doppler effects typical underwater channels. A very robust modulation able to guarantee connectivity in harsh environments (where spectral efficient solutions such as OFDM can be prevented) is the so called sweep-spread carrier (S2C) modulation, which is based on the usage of a linearly time-varying carrier. Underwater modems based on S2C modulations have been patented and successfully adopted in real-world deployments. In this paper, we analyze the performance of S2C both in simulation and infi…
Velocity estimation in wideband mobile stations equipped with multiple antennas
2009
©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Article also available from publisher: http://dx.doi.org/10.1109/VETECS.2009.5073907 A new method is proposed for estimating the velocity of wideband mobile stations (MSs) equipped with multiple antennas. The MS speed is determined using the well-known relationship between the direction-of-arrivals (DOAs) and the Doppler frequency shifts experienced by the mult…
Structural-relaxation phenomena in As–S glasses as probed by combined PAL/DBAR technique
2015
Abstract Experimental techniques exploring phenomena of positron–electron interaction, namely the positron annihilation lifetime spectroscopy and Doppler broadening of annihilation radiation, are shown to be very informative tools to study radiation- and thermally-induced phenomena in chalcogenide glasses of binary As–S system. Time-dependent processes of free-volume voids agglomeration (expansion), fragmentation (refining) and disappearing (contraction) are identified as main stages of physical aging in S-rich glasses, while a competitive channel of coordination topological defects formation associated with void charging becomes significant in a vicinity of near-stoichiometric glass compos…
Experiments and predictions of the transition of the flow pattern with impeller clearance in stirred tanks
2001
In the present work, the double- to single-loop flow pattern transition in a stirred vessel equipped with a Rushton turbine is investigated by Laser Doppler anemometry (LDA). In particular, the clearance at which such transition occurs is assessed by comparing axial velocity profiles underneath the impeller. Computational fluid dynamics (CFD) simulations of the same system are carried out, by employing the 'inner-outer' fully predictive computation strategy. The comparison of predicted results with the experimental data collected shows that the transition is well reproduced by simulations. A good agreement on the mean velocities is also observed but for the impeller discharge stream angle t…