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Biomedical subjects

J W Steadman

Publications and source records attributed to J W Steadman.

7 recordsLinked to original sources
PubMed1976

Renal dialysis membrane leak detector.

A leak developing in the membrane separating the blood from the dialysate in an artificial kidney machine requires immediate corrective action. The earliest possible action is desirable in order to minimize patient blood loss. This makes system sensitivity to hemoglobin concentration an important design criteria for blood leak detectors. The leak detector described in this paper matches the spectral properties of hemoglobin to those of the detector in order to achieve a maximum sensitivity while minimizing false alarms. The paper describes the instrumentation and circuitry as well as test results of simulated and clinical trials of the detection system.

Humans↗
PubMed1975

An analysis of the time course of gustatory neural adaptation in the rat.

Neural responses were recorded from the rat chorda tympani nerve following stimulation of the tongue with several concentrations of NaCl. These responses were integrated using a fast time constant (47 ms), and the time course of the decline in neural discharge from the peak of the transient response was computer analyzed. The time course of the adaptation process was described by a constant term and two exponentially decaying components, which most likely reflect the existence of two separate mechanisms contributing to the adaptation process in taste. The constant term and the amplitude of the second gradual exponential decay were correlated with NaCl concentration, whereas the amplitude of the initial rapidly declining exponential component was independent of stimulus intensity. The initial transient response of the chorda tympani nerve may be a function of the rate of stimulus adsorption, whereas the gradual second decline in the neural response may reflect an adaptive mechanism of the taste receptor cell.

Adaptation, Physiological↗
PubMed1975

Dangerous-electricity annunciator and detector.

Investigations into electrical accidents in hospitals have shown that the hazards are usually associated with the simultaneous use of two or more instruments. Recognizing this, several groups have written safety standards which limit the allowable potential difference between any two conductors near or connected to the patient. Implementing such a standard may be difficult since there may be a large number of such conductors and they must be tested using all combinations of two conductors. A simple scanning circuit using programmable operational amplifiers (PRAMs) and MOS digital circuitry makes the series of safety checks quickly and efficiently. The design includes both the ability to detect dangerous conditions and a digital annunciator to indicate which of the many leads being checked simultaneously is at fault. The scanning rate is rapid enough to allow the detection of dangerous transients. Preliminary results indicate that this portable, battery operated device is useful in providing an electrically safe environment for patients.

Accident Prevention↗