INTRODUCTION Serial monitoring of patients participating in clinical trials of carotid artery therapy requires noninvasive precision methods that are inexpensive, safe and widely available. Noninvasive ultrasonic duplex Doppler velocimetry provides a precision method that can be used for recruitment qualification, pre-treatment classification and post treatment surveillance for remodeling and r...

A new method of acquiring simultaneously the signal and reference channels used for interferometric planar Doppler velocimetry is proposed and demonstrated. The technique uses frequency division multiplexing (FDM) to facilitate the capture of the requisite images on a single camera, and is suitable for time-averaged flow measurements. Furthermore, the approach has the potential to be expanded t...

Photonic Doppler velocimetry (PDV) has rapidly become a standard diagnostic for measuring velocities in dynamic compression research. While free surface velocity measurements are fairly straightforward, complications occur when PDV is used to measure a dynamically loaded sample through a window. Fresnel reflections can severely affect the velocity and time resolution of PDV measurements, especi...

OBJECTIVES To describe the nature of flow velocity waveforms from fetal middle and distal venous pulmonary branches in the second half of normal pregnancy in relation to gestation, and to test repeatability and interrelationships of flow velocity waveform recordings from proximal, middle and distal venous pulmonary branches. DESIGN Cross-sectional study. SUBJECTS/METHODS A total of 111 norm...

A periodic shading mechanism (about 0.5 s period) is believed to be used by flagellated algae to detect light direction. Time changes in the orientation of a population of Haematococcus pluvialis under positive photoaxis conditions (cell samples were stimulated alternatively by two diametrically opposed beams of actinic light), have been investigated by analysing the Doppler shifts of laser lig...

Non-destructive measurements by laser Doppler velocimetry is employed to study unsteady flow in a hollow drum filled with liquid. The drum is suddenly accelerated from rest or is suddenly decelerated from a steady rotation to rest. Pure water and glycerin-water mixtures are used as the test liquid in which polyethylenelatex particles are mixed as the light scattering tracer. The boundary layer ...

arious techniques have been utilized for the asVsessment of mitral valve prosthesis function in man. Of the external methods, phonocardiography, fluoroscopy, and echocardiography have been most frequently employed. Routine cardiac catheterization, including pressure measurement and left ventriculography, supplies important data but does not directly estimate blood flow through the d c i a l val...

An experimental method for the determination of the flow-tracing fidelity of a scattering aerosol used in laser Doppler velocimeters was developed with particular reference to the subsonic turbulence measurements. The method employs the measurement of the dynamic response of a flow-seeding aerosol excited by acoustic waves. The amplitude and frequency of excitation were controlled in order to s...

Force sensors are at the heart of different technologies such as atomic force microscopy or inertial sensing. These sensors often rely on the measurement of the displacement amplitude of mechanical oscillators under applied force. The best sensitivity is typically achieved when the force is alternating at the mechanical resonance frequency of the oscillator, thus increasing its response by the ...