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Biomedical subjects

J A Clark

Publications and source records attributed to J A Clark.

At least 145 records · Page 8Linked to original sources
PubMed1978

The use of grafted polynomials and dummy variables in analyzing time series data.

Describes an innovative statistical method for analyzing single-S time series data. The S and data in the paper were selected from a larger study which applied operant conditioning to ambulation problems of severely handicapped patients and used positive verbal reinforcement. The method described is a variation of traditional multiple regression analysis described elsewhere as "grafted polynomials" (Draper & Smith, 1967; Fuller, Note 1). An extensive explanation of the use of dummy variables also is provided.

Conditioning, Operant↗
PubMed1977

Pollution indicator bacteria associated with municipal raw and drinking water supplies.

A total of 3819 bacterial cultures isolated from municipal water samples were identified using a combination of Enterotubules and confirmatory media. Frequency distributions for the different genera or groups of bacteria were similar for raw water and drinking water isolations, except for Escherichia organisms which doubled their frequency in raw water. Differences between the membrane filter (MF) and presence-absence (P-A) test with regard to types of organisms isolated were limited to Klebsiella organisms which were preferentially cultured from MF plates. Members of the genus Enterobacter were isolated more than twice as frequently as any of the other coliform genera dealt with in this study. Aeromonas organisms were detected almost as often as such individual genera as Escherichia, Citrobacter, or Klebsiella. Although non-lactose fermenting colonies (false-negatives) of the coliform genera would not be detected by the MF technique, their lack of detection would likely be offset by the Aeromonas colonies (false-positives). At least 25% of the coliform isolates were either anaerogenic or non-lactose fermenters and would therefore go undetected by the most probably number (MPN) technique.

Bacteria↗
PubMed1977

Voice controlled wheelchair.

A voice recognition and control system for use by quadriplegics and other severely physically disabled individuals in controlling a wheelchair has been developed and tested. Several wheelchair compatible features are included in the design--low power consumption (approximately 20 watts), small size (10"x11"x14"), low weight (approximately 22 lb), and no need for wheelchair modification (existing joystick control cable plugs directly into this system). The current system uses an eight word vocabulary (e.g., "forward," "slower," "right,") and a feedback control system to maintain the chair speed and direction. A recognition rate of more than 90% has been attained in laboratory tests with experienced speakers. Future system improvements are planned to increase the recognition rate and practical utility of the chair. The results of laboratory tests with normal and quadriplegic subjects indicate that voice commands are potentially a useful and practical means of wheelchair control. The effects of environmental noise are investigated and found to be minimally deleterious.

Biomedical Engineering↗
PubMed1976

Personality deviancy and prison incarceration.

This investigation was designed to study personality differences among prison inmates that could be attributed to the number of felony offenses and the length of incarceration. MMPI profiles of 93 inmates of a medium security prison were obtained and analyzed. Special attention was directed to the five MMPI variables K, D, PD, SC, and MA. These five variables taken collectively successfully differentiated first offenders from repeaters and short-term from long-term inmates. The results support the hypothesis that increased incarceration has a harmful effect upon personality.

Antisocial Personality Disorder↗
PubMed1975

The effect of tryptophan and a tryptophan/5-hydroxytryptophan combination on indoles in the brains of rats fed a tryptophan deficient diet.

Rats maintained on a tryptophan deficient diet had reduced brain and serum tryptophan and brain 5-hydroxyindolacetic acid levels compared to controls. 5-Hydroxytryptophan and L-tryptophan administered to these deficient rats in a combination (5:95) produced a greater elevation of indolamines and tryptophan in the brain than either amino acid alone. In rats maintained on a normal diet the urinary output of 3-hydroxykynurenine was considerably reduced by treatment with the combination of amino acids as compared to tryptophan treatment. 5-Hydroxytryptophan reduced the induction of kynurenine synthesis in the liver produced by tryptophan, implying that it is capable of inhibiting the enzyme tryptophan pyrrolase in vivo. It is suggested that the possession by 5-hydroxytryptophan of tryptophan pyrrolase inhibitory properties may make the administration of the combination a better treatment of depressed patients exhibiting an indolamine deficit than either amino acid alone.

3-Hydroxyanthranilic Acid↗