In this article, interleaved finite difference time domain methods are developed for the purpose of simulating the dynamics of the acoustic bore, using, as a starting point, an impedance formulation of wave propagation in an acoustic tube; attention is focused here on modeling of viscothermal and radiation losses in the time domain. In particular, in contrast to other methods, the bore, includi...

This study seeks to explain mechanisms responsible for the contour of pressure and flow waves and the pattern of vascular impedance in human systemic arteries. Pulsatile pressure and flow were recorded from the ascending aorta of seven patients undergoing open heart surgery and from the ascending aorta and other arteries of 17 patients at diagnostic catheterization. Ascending aortic pressure/fl...

Photomultipliers are fast, sensitive and low noise light detectors which operate across the ultraviolet–optical–near infra red region of the electromagnetic spectrum. Sensitivity is determined by the composition of the photocathode layer in which incident photons excite photoelectrons and the thickness of this layer. Incident light is partially reflected from and partially transmitted through t...

This study seeks to explain mechanisms responsible for the contour of pressure and flow waves and the pattern of vascular impedance in human systemic arteries. Pulsatile pressure and flow were recorded from the ascending aorta of seven patients undergoing open heart surgery and from the ascending aorta and other arteries of 17 patients at diagnostic catheterization. Ascending aortic pressure/fl...

A tracking impedance estimation technique was developed to follow the changes in total respiratory impedance (Zrs) during slow total lung capacity maneuvers in six anesthetized and mechanically ventilated BALB/c mice. Zrs was measured with the wave-tube technique and pseudorandom forced oscillations at nine frequencies between 4 and 38 Hz during inflation from a transrespiratory pressure of 0-2...

The oscillatory flow of blood through a stenosed artery is investigated in this paper in presence of magnetic field. The laminar, incompressible, fully developed, Newtonian flow of blood in an artery having mild stenosis is numerically studied under the action of transverse magnetic field and the numerical results are obtained for the oscillatory flow of blood using Shooting method. It is assum...

This study seeks to explain mechanisms responsible for the contour of pressure and flow waves and the pattern of vascular impedance in human systemic arteries. Pulsatile pressure and flow were recorded from the ascending aorta of seven patients undergoing open heart surgery and from the ascending aorta and other arteries of 17 patients at diagnostic catheterization. Ascending aortic pressure/fl...

Measurements and predictions have been made of the absorption coefficient and the surface acoustic impedance of poroelastic plates clamped in a large impedance tube and separated from the rigid termination by an air gap. The measured and predicted absorption coefficient and surface impedance spectra exhibit low frequency peaks. The peak frequencies observed in the absorption coefficient are clo...

BACKGROUND Retention of airway secretions is a common and serious problem in ventilated patients. Treating or avoiding secretion retention with mucus thinning, patient-positioning, airway suctioning, or chest or airway vibration or percussion may provide short-term benefit. METHODS In a series of laboratory experiments with a test-lung system we examined the role of ventilator settings and lu...

This paper presents two key technology components required for the development of a self-powered, wireless, active acoustic liner system. The envisioned system consists of a tunable Helmholtz resonator for acoustic impedance boundary condition modification and an acoustic energy reclamation module as a system power supply. The common electroacoustic element for both of these components is an el...