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Biomedical subjects

E Kresch

Publications and source records attributed to E Kresch.

8 recordsLinked to original sources
PubMed1972

Cross-sectional shape of collapsible tubes.

In order to quantify the collapse phenomenon in veins, this paper presents a mathematical analysis of the cross-sectional shape of a flexible tube as its internal pressure varies. Quantitative results are presented in terms of the physical parameters of the tube, such as wall thickness and Young's modulus. It is assumed that the tube is thin walled, that no stretching occurs, that the cross-sectional shape is elliptical when the transmural pressure is zero, and that the longitudinal prestress is zero. The equations were solved on a digital computer which displayed the cross-sectional shapes on an oscilloscope, which were then photographed. A selection of these photographs is presented. Curves are shown which give the cross-sectional area and compliance as functions of transmural pressure. Other curves are shown which are useful for interpolation, and for use in the experimental determination of the physical parameters which may otherwise be difficult or impossible to measure accurately.

Biomechanical Phenomena↗
PubMed1970

On the possibility of nonthermal biological effects of pulsed electromagnetic radiation.

Two mechanisms for the interaction of alternating electrical fields with biological tissue are the development of heat, via i(2)R losses, and field-induced force effects, via differences in passive electrical properties. It has been shown that for continuous wave (CW) fields in media of physiologic electrical conductivity, the development of heat (>1 degrees C) always precedes the possible appearance of a field-induced force effect. Using pearl-chain formation as a model effect and experimentally demonstrating that its time constant varies inversely as the square of the electrical field strength, we show that a pulsed field has no greater ability than a CW field of equal rms field strength to produce a field-induced force effect. Thus, the statement above for CW fields can be broadened to include pulsed fields of any description. By relating incident power density to electric field strength in tissue, we show that the American National Standards Institute's radiation protection guide obviates the production of genetic effects in man, if they exist, via field-induced force effects.

Electric Conductivity↗
PubMedDate not supplied

A computerized hospital maintenance system.

The Biomedical Instrumentation Department at Thomas Jefferson University Hospital maintains most of the clinical equipment owned by the hospital and provides support to six other hospitals, as well. In order to document these services, a computerized support system has been developed. This system maintains the inventory of equipment, documents the occurrence of repair and preventive maintenance procedures, generates lists of items due for maintenance and inspection, and prints reports and summaries of all activities performed by department staff. The system was designed for ease of use and requires a minimum of training for personnel who use it.

Computers↗