BACKGROUND The purpose of the present study was to determine the role of autonomic neural control of dynamic cerebral autoregulation in humans. METHODS AND RESULTS We measured arterial pressure and cerebral blood flow (CBF) velocity in 12 healthy subjects (aged 29+/-6 years) before and after ganglion blockade with trimethaphan. CBF velocity was measured in the middle cerebral artery using tra...

BACKGROUND Conventional Doppler parameters are unreliable for estimating left ventricular (LV) filling pressures in hypertrophic cardiomyopathy (HCM). This study was undertaken to evaluate flow propagation velocity by color M-mode and early diastolic annular velocity (Ea) by tissue Doppler 2 new indices of LV relaxation, combined with mitral E velocity for estimation of filling pressures in HCM...

This paper deals with a theoretical investigation of heat and mass transfer with thermal radiation analysis on hydromagnetic peristaltic Prandtl fluid model with porous medium through an asymmetric tapered vertical channel under the influence of gravity field. Analytical results are found for the velocity, pressure gradient, pressure rise, frictional force, temperature and concentration. The in...

In this paper, an upper bound approach is used to analyze the tube extrusion process through rotating conical dies with large mandrel radius. The material under deformation in the die and inside the container is divided to four deformation zones. A velocity field for each deformation zone is developed to evaluate the internal powers and the powers dissipated on all frictional and velocity disco...

this paper describes the effects of induced magnetic field and partial slip on the peristaltic flow of a couple stress fluids in an asymmetric channel. the two dimensional equation of couple stress fluid are simplified by making the assumptions of long wave length and low reynolds number. the exact solutions of reduced momentum equation and magnetic force function have been computed in wave fra...

The flow field associated with the passage of the turbulent spot in a 3–D duct with streamline divergence under zero pressure gradients was investigated and displayed as contour plots of the velocity perturbation in plan and elevation view of the spot. It suggests that, streamline divergence has no strong effect on the internal structure of the spot and eddies and their propagation in the downs...

This paper presents an incompressible smoothed particle hydrodynamics (SPH) model to simulate wave propagation in a free surface flow. The Navier-Stokes equations are solved in a Lagrangian framework using a three-step fractional method. In the first step, a temporary velocity field is provided according to the relevant body forces. This velocity field is renewed in the second step to include t...

abstract   background: postural instability has been identified as a potential precursor of falls in elderly subjects. postural stability in quiet stance is commonly assessed with center of pressure (cop) measures. the purpose of this study was to determine testretest reliability and minimal detectable change (mdc) for the center of pressure (cop) measures in the elderly subjects.   methods: ei...

The effects of supine bicycle exercise on the input impedance of the ascending aorta were studied in thirteen male subjects undergoing cardiac catheterization, but in whom no cardiovascular disease was found. Ascending aortic flow velocity and pressure were recorded simultaneously from a multisensor catheter with an electromagnetic flow velocity probe and a pressure sensor mounted at the same l...

There are two main approaches for pore pressure estimation: geological using basin modeling and geophysical using seismic velocity. In this paper, seismic velocity was used for pore pressure estimation. The impact of the input data quality in terms of signal-to-noise ratio (SNR) and frequency bandwidth on the accuracy of seismic velocity analysis and, ultimately, the reliability of pore pressur...