Harold Richard Stewart

Author:

Harold Charles Stewart

ISBN #:

0407138803

Author:

Harold Charles Stewart

ISBN #:

0407138811

Author:

Harold Charles Stewart

ISBN #:

0407155031

Author:

Harold Charles Stewart

ISBN #:

0407155015

Author:

Harold Charles Stewart

ISBN #:

0407155023

Author:

Harold D. Stewart

ISBN #:

0819456896

Author:

Harold D. Stewart

ISBN #:

0819461512

Author:

Harold Stewart

ISBN #:

0804818940

US Patent:

50529340, Oct 1, 1991

Filed:

Apr 20, 1990

Appl. No.:

7/513269

Inventors:

Ronald F. Carey - Columbia MD
Bruce A. Herman - Rockville MD
Ronald A. Robinson - Germantown MD
Harold F. Stewart - Nashville TN
Richard G. Hoops - Potomac MD
George H. Douglas - Mt. Airy MD

Assignee:

The United States of America as represented by the Department of Health
and Human Services - Washington DC

International Classification:

G09B 2378
A61B 800

US Classification:

434268

Abstract:

Apparatus is provided to serve as a phantom for evaluation of prosthetic valves and cardiac ultrasound procedures, wherein a controlled pulsatile flow of a blood-mimicking fluid is passed through a multi-chambered region into which are mounted mitral and aortic valves and adjustably positionable ultrasound transducers. A low friction, drive which involves very low levels of extraneous vibrational inputs, is provided with adjustment of both the volume flow rate of blood-mimicking fluid moved in each operational pulse with further control provided by relatively easily adjusted screws to selectively regulate the systolic and diastolic times of the pulsatile flow generated by a bellows arrangement. Windows made of silicone elastomer material presenting both tissue-equivalent impedance for ultrasound transmission and tissue-equivalent attenuation of the ultrasound are provided in controlled thickness to permit detailed observation of valvular flow parameters of interest, e. g. , flow velocity distributions observed in the transesophogeal and apical directions.

US Patent:

41332121, Jan 9, 1979

Filed:

Oct 31, 1977

Appl. No.:

5/847022

Inventors:

Bruce A. Herman - Rockville MD
Harold F. Stewart - Rockville MD

Assignee:

The United States of America as represented by the Secretary of the
Department of Health, Education & Welfare - Washington DC

International Classification:

G01H 312

US Classification:

73647

Abstract:

A system and technique for determining the total radiated ultrasonic power output from a diagnostic ultrasound device having an output transducer includes a water chamber having a parabolic reflector. The transducer is mounted on the chamber at a location so that acoustic power from the transducer is focussed by the parabolic reflector to a first thermistor chip mounted in the chamber on a sound-absorbing rubber plate. The rise in temperature of the thermistor chip due to sound absorption changes its resistance. The thermistor chip is connected in one leg of a Wheatstone bridge. A reference thermistor chip is mounted on the rubber plate away from the ultrasonic beam and is connected in an opposite leg of the bridge. Starting from a null setting of the bridge, the output of the bridge after a suitable "response time" is in accordance with the acoustic energy delivered by the transducer.

US Patent:

51388715, Aug 18, 1992

Filed:

Apr 6, 1990

Appl. No.:

7/505268

Inventors:

Stephen M. Retta - Hyattsville MD
Jean Rinaldi - Silver Spring MD
Ronald Carey - Columbia MD
William A. Herman - Silver Spring MD
T. Whit Athey - Rockville MD
Bruce A. Herman - Rockville MD
Harold Stewart - Nashville TN

Assignee:

The United States of America as represented by the Department of Health
and Human Services - Washington DC

International Classification:

G01M 320

US Classification:

73 38

Abstract:

An apparatus and method for evaluating the permeability of membrane articles, particularly condoms and gloves, is designed to quantify physiologic conditions which exist during use of the articles. Permeability is determined by monitoring fluorescent microspheres of approximately the size of HIV which pass through the membrane articles.