Search results for " ultrasonic"
showing 10 items of 344 documents
ASSOCIATION OF RENAL RESISTIVE INDEX WITH MARKERS OF EXTRARENAL VASCULAR CHANGES IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS
2016
Introduction: Recent data suggest that renal hemodynamic parameters obtained by duplex Doppler sonography, especially the intrarenal resistive index (RRI), may be associated with systemic vascular changes. However, limited and conflicting data exist about the relationship between aortic stiffness and RI in autoimmune diseases, like systemic lupus erythematosus (SLE). Aim: To evaluate the relationship between RRI and arterial stiffness, assessed by aortic pulse wave velocity (aPWV), and between RRI and carotid atherosclerosis, evaluated by intima-media thickness (IMT) measurement in patients with SLE. Methods: In this cross-sectional study, we enrolled 39 SLE subjects (mean age 39 years) tha…
The decision process in forward-masked intensity discrimination: evidence from molecular analyses.
2009
In a two-interval forced-choice intensity discrimination task presenting a fixed increment, the level of the forward masker in interval 1 and interval 2 was sampled independently from the same normal distribution on each trial. Mean and standard deviation of the distribution were varied. Correlational analyses of the trial-by-trial data revealed different decision strategies depending on the relation between mean masker level and standard level. If the two levels were identical, listeners tended to select the interval containing the higher-level masker, behaving like an energy detector at the output of a temporal window of integration. For mean masker level higher than the standard level, m…
Low-Frequency Therapeutic Ultrasound with Varied Duty Cycle: Effects on the Ischemic Brain and the Inner Ear
2009
Sonothrombolysis is a promising modality for acute stroke treatment. In vitro data suggest a duty cycle dependence of sonothrombolytic efficacy of low-frequency applications. The aim of our study was to examine its impact on safety issues in a rat model of middle cerebral artery occlusion. Rats were exposed to transcranial 60-kHz ultrasound with varied duty cycles. To determine effects on the inner ear, the acoustic threshold was determined in additional healthy animals (acoustic evoked potentials). A short duty cycle (20%) resulted in significant adverse effects (ischemic volume, hemorrhage, functional outcome), which was not observed in longer duty cycle (80%). Continuous-wave insonation …
Detrimental Effects of 60 kHz Sonothrombolysis in Rats with Middle Cerebral Artery Occlusion
2008
Recent studies have raised concerns about the safety of low frequency ultrasound in transcranial therapeutic application in cerebral ischemia. This study was designed to evaluate safety aspects and potential deleterious effects of low frequency, 60 kHz ultrasound in treatment of experimental middle cerebral artery occlusion (MCAO) in rats. Forty-five male Wistar rats were submitted to either temporary (90 min; groups I and II) or permanent MCAO (groups III and IV) using the suture technique. All animals received recombinant tissue plasminogen activator (rt-PA) starting 90 min after the beginning of occlusion. Groups I and III were additionally treated with 60 kHz ultrasound (time average ac…
Clinical significance of abdominal lymphadenopathy in chronic liver disease
2002
Abstract The possibility of assessing the relationship of ultrasound (US)-detected abdominal lymphadenopathy with etiology, biochemical findings, and histologic data in patients with chronic liver disease was evaluated. US examination of the upper abdomen was performed in 321 consecutive patients with various chronic liver disorders and 56 control patients. The prevalence of lymphadenopathy in chronic liver disease was 38%. This prevalence varied according to etiology of liver disease, from 50% in chronic hepatitis C virus (HCV) to less than 10% in alcoholicc cirrhosis and hepatitis B-virus (HBV)-related chronic liver disease. Patients with lymphadenopathy showed significantly higher serum …
Effects of Steatosis on Hepatic Hemodynamics in Patients with Metabolic Syndrome
2015
The aim of our study was to assess the hemodynamic changes in hepatic and splenic circulation using B-mode ultrasonography and color Doppler ultrasonography, in a population of patients with metabolic syndrome divided with respect to the presence or absence of steatosis diagnosed by ultrasonography. One hundred forty-one patients were included in the study. The severity of non-alcoholic fatty liver disease was classified as mild, moderate or severe. Visceral fat thickness, longitudinal diameter of the spleen, diameter of the portal vein, mean maximum portal vein flow velocity, hepatic artery and splenic artery resistivity indexes and hepatic vein flow phasicity were measured. Non-alcoholic …
Numerical study for a new methodology of flaws detection in train axles
2013
Train loads and travel speeds have increased over time, requiring more efficient non-destructive inspection methods. Railway axles are critical elements; despite being designed to last more than 20 years several cases of premature failure have been recorded. Train axles are inspected regularly, but the limits associated to the traditional inspection technologies create a growing interest towards new solutions. Here a novel non-destructive inspection method of in-service axles based on non-contact data collection is presented. The propagation of surface waves, generated by a thermo-elastic laser source, is investigated using a finite element method based on dynamic explicit integration. Coup…
Loudness changes induced by a proximal sound: loudness enhancement, loudness recalibration, or both?
2007
The effect of a forward masker on the loudness of a target tone in close temporal proximity was investigated. Loudness matches between a target and a comparison tone at the same frequency were obtained for a wide range of target and masker levels. Contrary to the hypothesis by Scharf, Buus, and Nieder [J. Acoust. Soc. Am. 112, 807-810 (2002)], these matches could not be explained by an effect of the masker on the comparison loudness, which was measured by loudness matches between the comparison and a fourth tone separated in frequency from the comparison and the masker. The data thus demonstrate that a forward masker has an effect on the loudness of a proximal target. The results are compat…
Structural study of gallium oxynitrides prepared by ammonolysis of different oxide precursors
2009
International audience; A comparative structural study has been carried out on gallium oxynitride powders using XRD and Raman spectroscopy. Gallium oxynitrides have been prepared by ammonolysis of either NiGa2O4 ternary oxide or the citrate method-derived amorphous oxide. Their crystal chemistry is different and appears to be influenced by the nature of the oxide precursor: whereas gallium oxynitride obtained from amorphous gallium oxide crystallizes with the common wurtzite structure, gallium oxynitride obtained from NiGa2O4 crystallizes with an original structure that we have identified as the carborundum II (B6) structure type or 6H-SiC. As far as we know, this is the first 6H-SiC struct…
Influence of pressure on ultrasonic cavitation activity in room temperature ionic liquids: An electrochemical study
2019
Abstract This paper provides proofs of the respective contributions of dissolved gases and solvent vapor on cavitation activity in sonoreactors. This activity can be detected by electrochemistry because the fluctuating events measured at the electrode surface are only linked to physical effects of cavitation. As ionic liquids present very low volatilities, their vaporization is reduced, and cavitation bubbles only depend on the presence of gases. Then, cavitation activity may be trigged by reactor atmosphere control. Applying severe depression within an irradiated ionic liquid medium contributes to removing dissolved gases, thus quenching cavitation activity. A specific sonoelectrochemical …