In this study we determined mean-average wall shear stress values in the common carotid artery and assessed if there is a difference in mean-average WSS between: 1) patients with bilateral carotid bifurcation disease and 2) similar-aged volunteers with no evidence of disease. Sixteen patients with bilateral disease of the carotid bifurcation, and 8 volunteers were included in the study. Magneti...

We noninvasively evaluated the effects of nicardipine on cerebral vascular responses to hypocapnia and blood flow velocity in the middle cerebral artery of 10 patients aged 17-60 (mean +/- SD 46.1 +/- 11.8) years. During fentanyl/diazepam/nitrous oxide anesthesia, mean blood flow velocity in the middle cerebral artery was measured and cerebral vascular reactivity to hypocapnia induced by hyperv...

Asymptotic reductions of the Fanno model for one-dimensional turbulent compressible flow of a perfect gas in a long tube are investigated. Conservation laws are derived using the multiplier method for a nonlinear wave equation and a nonlinear diffusion equation for the mean velocity and a nonlinear diffusion equation for the mean pressure. Two conserved quantities for the mean velocity are obta...

Transcranial Doppler ultrasound monitoring of cerebral blood flow velocity (CBFV) was performed on 17 children (age range 8 days to 6 years) with pyogenic meningitis. Serial measurements of the peak systolic, end diastolic, mean flow velocity, and resistance index (equal to peak systolic velocity minus end diastolic velocity divided by peak systolic velocity) were obtained over the period of th...

Abstract Background: Transcranial Doppler ultrasonography results have not been previously studied in among Iranian sickle cell anemia patients. The present study was performed to evaluate the pattern of intracranial flow velocities among Iranian children with sickle cell anemia and the hematological parameters that can affect the time-averaged mean of maximum velocity in major intracranial...

Background: Beta-thalassemia intermedia (BTI) is a type of hemoglobinopathy with an increased risk of cerebrovascular accidents, and transcranial cerebral Doppler ultrasonography (TCD) through determining the mean cerebral blood flow velocity (CBFV) can serve to predict the risk of a developing stroke. This study aims to compare patients with beta-thalassemia intermedia and healthy individuals ...

BACKGROUND The pulsatility index (PI) and resistive index (RI) are used as markers of peripheral vascular resistance. Recently intrarenal PI and RI were introduced for the evaluation of the severity of acute and chronic renal failure, as well as for the diagnosis of renal artery stenosis and kidney graft rejection. In the present study, we evaluated intrarenal PI and RI in patients with essenti...

This study investigates cerebral blood flow (CBF) velocity in humans before, during, and after 24 h of 6 degree head-down tilt (HDT), which is a currently accepted experimental model to simulate microgravity. CBF velocity was measured by use of the transcranial Doppler technique in the right middle cerebral artery of eight healthy male subjects. Mean CBF velocity increased from the pre-HDT upri...

OBJECTIVES This study investigated the velocity distribution across the natural mitral valve. BACKGROUND Information about the blood velocity distribution across the mitral valve is of interest in basic fluid dynamic studies of the natural mitral valve and is needed for precise cardiac output estimates by Doppler echocardiography. METHODS The velocity distribution across the mitral valve wa...

In the developing flow region of a plunging jet, the verynear field (i.e. (x-x1)/d1 < 5) is strongly affected by the entrapment process at the impingement. New quantitative results show that, although the distributions of void fraction and mean velocity have smooth shapes, the flow is highly fluctuating and unstable. At a given location in the mixing layer, the probability distribution function...