The attenuation of a plane acoustic wave incident on a flat impedance surface in a sheared and viscous fluid is investigated numerically and asymptotically. Predictions of various boundary models of impedance surfaces in shear flow are tested by comparing their predicted reflection coefficient. It is found that viscosity has a significant effect, reducing the reflection of upstream propagating ...

Light-wave propagation in a randomly scattering but uniformly and coherently amplifying optical medium is analysed for the statistics of the coefficient of reflection r(l) that may now exceed unity, hence super-reflection. Uniform coherent amplification is introduced phenomenologically through a constant negative imaginary part added to the otherwise real dielectric constant of the medium, assu...

Mean and pulsatile components of hemodynamic load are related to cardiovascular disease. Vascular growth factors play a fundamental role in vascular remodeling. The links between growth factors and hemodynamic load components are not well described. In 3496 participants from the Framingham Heart Study third generation cohort (mean age: 40 9 years; 52% women), we related 4 tonometry-derived meas...

Mean and pulsatile components of hemodynamic load are related to cardiovascular disease. Vascular growth factors play a fundamental role in vascular remodeling. The links between growth factors and hemodynamic load components are not well described. In 3496 participants from the Framingham Heart Study third generation cohort (mean age: 40±9 years; 52% women), we related 4 tonometry-derived meas...

Active boundary surfaces intended to control reverberation or other characteristics of enclosed sound fields have often been investigated using plane wave tubes. This paper presents an analysis of actively terminated semi-infinite and finite-length plane wave tubes to provide needed clarification of the effects of these surfaces. By considering relationships between complex pressure-amplitude r...

The ultrasonic attenuation coefficient of a fluid or solid material is an acoustic parameter routinely estimated in nondestructive evaluation (NDE) and biological tissue characterization. In this paper, a new measurement and analysis technique for estimating the attenuation coefficient as a function of frequency for a fluid or solid is described. This broadband technique combines two establishe...

OBJECTIVE Beta-blocking therapy is the standard therapy in non-operated Marfan patients, however its efficacy after entire aortic replacement is unknown. The aim of this study was to describe the influence of (nearly) entire aortic replacement and beta-blocking therapy on blood pressure and wave reflections in Marfan patients. METHODS Four Marfan patients (mean age 31+/-3 years) and 8 age mat...

Radar inference of the bulk properties of glacier beds, most notably identifying basal melting, is, in general, derived from the basal reflection coefficient. On the scale of an ice sheet, unambiguous determination of basal reflection is primarily limited by uncertainty in the englacial attenuation of the radio wave, which is an Arrhenius function of temperature. Existing bed-returned power alg...

This paper concerns amplitude-preserving kinematically equivalent offset continuation (OC) operators. I introduce a revised partial differential OC equation as a tool to build OC operators that preserve offset-dependent reflectivity in prestack processing. The method of characteristics is applied to reveal the geometric laws of the OC process. With the help of geometric (kinematic) construction...

The main goal is to analyze the influence of cracks on azimuthal variations amplitude. We restrict our investigation a single set vertical, circular, and flat cavities aligned along horizontal axis. Such are embedded in either transversely isotropic background with vertical symmetry axis (VTI) or surroundings. employ effective medium theory obtain orthotropic VTI homogenised medium, respectivel...