Search results for "Low velocity"
showing 10 items of 231 documents
Energy harvesting by waste acid/base neutralization via bipolar membrane reverse electrodialysis
2020
Bipolar Membrane Reverse Electrodialysis (BMRED) can be used to produce electricity exploiting acid-base neutralization, thus representing a valuable route in reusing waste streams. The present work investigates the performance of a lab-scale BMRED module under several operating conditions. By feeding the stack with 1 M HCl and NaOH streams, a maximum power density of ~17 W m−2 was obtained at 100 A m−2 with a 10-triplet stack with a flow velocity of 1 cm s−1, while an energy density of ~10 kWh m−3 acid could be extracted by a complete neutralization. Parasitic currents along feed and drain manifolds significantly affected the performance of the stack when equipped with a higher number of t…
Clinical-anamnestic and instrumental data in outpatients suffering from venous disease
1995
The authors studied 200 consecutive outpatients with symptoms due to venous disease of the lower limbs. All the patients underwent anamnestic, clinical and instrumental evaluation (c.w. Doppler velocimetry and strain-gauge plethysmography). The results of this study showed that some anamnestic and clinical data are significantly related to venous disease detected by instrumental techniques. The superficial and deep vein hypertension were, instead, correlated to oral contraceptive use.
Ticlopidine in the Treatment of Multiple Atherosclerotic Arteriopathy: a Strain Gauge Plethysmography and Döppler Spectrum Analysis Evaluation
1987
The effect of ticlopidine was compared with flunarizine in patients with iliac–femoral and / or femoral–popliteal arteriosclerotic arteriopathy accompanied by lesions of the cervical arteries of no haemodynamic significance. In the lower limbs, plethysmography (strain gauge measurements) and Döppler ultrasonography integrated by spectral analysis of the cervical arteries showed qualitative and quantitative improvements of the regional haematic flow. Side-effects were negligible which suggests that ticlopidine is useful in the treatment of multiple arteriosclerotic arteriopathy.
THE ACCELERATING JET OF 3C 279
2012
Analysis of the proper motions of the subparsec scale jet of the quasar 3C 279 at 15 GHz with the Very Long Baseline Array shows significant accelerations in four of nine superluminal features. Analysis of these motions is combined with the analysis of flux density light curves to constrain values of Lorentz factor and viewing angle (and their derivatives) for each component. The data for each of these components are consistent with significant changes to the Lorentz factor, viewing angle, and azimuthal angle, suggesting jet bending with changes in speed. We see that for these observed components Lorentz factors are in the range Γ = 10-41, viewing angles are in the range = 0.°1-5.°0, and in…
Efficiency of a digital particle image velocimetry (DPIV) method for monitoring the surface velocity of hyper-concentrated flows
2018
Digital particle image velocimetry records high resolution images and allows the identification of the position of points in different time instants. This paper explores the efficiency of the digital image-technique for remote monitoring of surface velocity and discharge measurement in hyper-concentrated flow by the way of laboratory experiment. One of the challenges in the application of the image-technique is the evaluation of the error in estimating surface velocity. The error quantification is complex because it depends on many factors characterizing either the experimental conditions or/and the processing algorithm. In the present work, attention is devoted to the estimation error due …
Dynamic cerebrovascular autoregulation in patients prone to postural syncope: Comparison of techniques assessing the autoregulation index from sponta…
2021
Abstract Three approaches to the assessment of cerebrovascular autoregulation (CA) via the computation of the autoregulation index (ARI) from spontaneous variability of mean arterial pressure (MAP) and mean cerebral blood flow velocity (MCBFV) were applied: 1) a time domain method (TDM); 2) a nonparametric method (nonPM); 3) a parametric method (PM). Performances were tested over matched and surrogate unmatched pairs. Data were analyzed at supine resting (REST) and during the early phase of 60° head-up tilt (TILT) in 13 subjects with previous history of postural syncope (SYNC, age: 28 ± 9 yrs.; 5 males) and 13 control individuals (noSYNC, age: 27 ± 8 yrs.; 5 males). Analysis was completed b…
Sympathetic Vasomotor Response of the Radial Artery in Patients With Diabetic Foot Syndrome
2003
OBJECTIVE—Neurophysiological assessment of the peripheral autonomic system is characterized by various limitations. An alternative approach to laser Doppler and venous plethymography is the assessment of the sympathetic vasomotor response of the radial artery obtained by continuous wave Doppler sonography. Nomogram data have been established and demonstrate the temporary disappearance of diastolic flow after coughing or deep inspiration. RESEARCH DESIGN AND METHODS—We assessed the sympathetic vasomotor response in 25 patients (mean age 64 years, range 43–76) with diabetic foot syndrome. The Doppler data were correlated with nerve conduction studies of the median and peroneal nerve, the exte…
Changes in the cerebrovascular effects of endothelin-1 and nicardipine after experimental subarachnoid hemorrhage.
1993
The role of endothelium-related factors in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH) has gained interest since the discovery of endothelin-1 (ET-1). We have examined, before and after SAH, the responsiveness of the cerebrovascular bed of the goat to ET-1, the sources of Ca2+ in ET-1-induced responses, and the ability of the Ca2+ entry blocker nicardipine to counteract them. Before SAH, injection of ET-1 into the cerebral circulation increased cerebrovascular resistance, thereby producing dose-dependent reductions in cerebral blood flow (CBF), which were prevented by nicardipine. In isolated middle cerebral arteries, ET-1 induced concentration-dependent contr…
Deep vein thrombus formation induced by flow reduction in mice is determined by venous side branches.
2013
Interaction between vascular wall abnormalities, inflammatory leukocytes, platelets, coagulation factors and hemorheology in the pathogenesis of deep vein thrombosis (DVT) is incompletely understood, requiring well defined animal models of human disease. METHODS AND RESULTS: We subjected male C57BL/6 mice to ligation of the inferior vena cava (IVC) as a flow reduction model to induce DVT. Thrombus size and weight were analyzed macroscopically and sonographically by B-mode, pulse wave (pw) Doppler and power Doppler imaging (PDI) using high frequency ultrasound. Thrombus size varied substantially between individual procedures and mice, irrespective of the flow reduction achieved by the ligatu…
The Long-Term Effect of Sevoflurane on Neuronal Cell Damage and Expression of Apoptotic Factors After Cerebral Ischemia and Reperfusion in Rats
2006
We investigated the long-term effects of sevoflurane on histopathologic injury and key proteins of apoptosis in a rat hemispheric ischemia/reperfusion model. Sixty-four male Sprague-Dawley rats were randomly assigned to Group 1 (fentanyl and N2O/O2; control) and Group 2 (2.0 vol% sevoflurane and O2/air). Ischemia (45 min) was produced by unilateral common carotid artery occlusion plus hemorrhagic hypotension (mean arterial blood pressure 40 mm Hg). Animals were killed after 1, 3, 7, and 28 days. In hematoxylin and eosin-stained brain sections eosinophilic hippocampal neurons were counted. Activated caspase-3 and the apoptosis-regulating proteins Bax, Bcl-2, Mdm-2, and p53 were analyzed by i…