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Biomedical subjects

J Powell

Publications and source records attributed to J Powell.

At least 289 records · Page 16Linked to original sources
PubMed1970

Sequelae of neonatal jaundice.

A total of 371 newborn infants falling into 3 groups, non-haemolytic jaundice, haemolytic jaundice, and non-jaundiced controls, have been reassessed in the 6th year of life as regards neurological, audiological, and psychological function. Neurological handicap was concentrated among the infants of low birth weight and was not related to jaundice, apart from one case of athetoid cerebral palsy with deafness. No other cases of perceptive deafness were discovered. Intelligence testing on the Stanford Binet scale showed no relation between depth of jaundice and I.Q.These findings support the majority of reports in the literature that reduction in intelligence does not occur in non-haemolytic jaundiced babies with serum bilirubin below about 20 mg./100 ml. In haemolytic jaundice slight doubt remains. There is no indication for changing present standards for exchange transfusion.

Anemia, Hemolytic↗
PubMed1970

Positive reinforcement and suppression from the same occurrence of the unconditioned stimulus in a positive conditioned suppression procedure.

Responding of rats was maintained on a variable-interval schedule of food reinforcement. The same response also produced a blinking light followed by electrical brain stimulation according to a fixed-interval schedule. This conjoint schedule produced two behavioral changes. First, instead of a steady rate of responding throughout the session, which would be characteristic of the variable interval food schedule alone, responding between occurrences of the light-brain stimulation pairings became positively accelerated and thus was more characteristic of the fixed-interval schedule of these pairings. Second, food responding was suppressed during the light that preceded brain stimulation. These results indicate that positive reinforcement and suppression resulted from the same occurrence of the light-brain stimulation combination. This finding suggests that stimuli such as conditioned reinforcers that precede an unconditioned reinforcer may have a suppressive effect upon responding in their presence that is being maintained by another reinforcer.

Journal Article↗
PubMed1969

Behavioral engineering: the use of response priming to improve prescribed self-medication.

A major problem in outpatient treatment has been the extreme irregularity with which patients use medication prescribed for them. As a new approach to resolving this problem, a portable operant apparatus was developed based on response priming and escape reinforcement. The apparatus sounded a tone at the time that a pill was to be taken. When the user turned a knob to terminate the tone, the apparatus delivered the pill into the user's hand. The apparatus was evaluated with six normal adults using a medically inert pill. A greater proportion of the pills were taken by each subject when using the special apparatus as compared with the use of a portable alarm timer or the usual wristwatch. These results demonstrate a new approach for increasing the regularity of self-administration of medicines.

Journal Article↗
PubMed1969

Conditioned suppression as a sensitive baseline for social facilitation.

The key pecking of pigeons maintained on a variable-interval schedule of food reinforcement was suppressed during occasional presentations of a warning stimulus paired with electric shock. On alternate sessions, a co-actor pigeon was visible in an adjoining chamber where it emitted the same food-reinforced key peck during the warning stimulus that signalled shock for the subject. With no shock and at low shock intensities, where the subject's responding was not suppressed or suppressed only slightly, the co-actor had little effect. At the higher shock intensities, where the subject's responding was reduced by at least 40%, the response rate during the warning stimulus was consistently higher when the co-actor was present. One explanation of these results assumes a special relationship between social stimuli and aversive stimuli in which the presence of another animal reduces emotional reactions and thereby allows operant responses to increase. This was not the case here because the mere presence of the co-actor did not maintain social facilitation. Rather, the present results, taken in conjunction with previous findings, suggest that changes in social and non-social variables which affect the rate of food-reinforced responding may produce proportionately larger changes in responding when that responding is suppressed by aversive stimulation than when it is not.

Journal Article↗
PubMed1968

Behavioral engineering: the reduction of smoking behavior by a conditioning apparatus and procedure.

Recent findings from animal conditioning studies have revealed methods of reducing responses to a very low level with a minimum of aversive by-products. These findings were incorporated into the design of a cigarette case that automatically locked itself for a period of time after a cigarette was removed from it. The next cigarette could be taken at the end of the interval, which was signalled by distinctive stimuli. Five heavy smokers were allowed to become accustomed to using the case. Then, the duration for which the case was locked was gradually increased over a period of weeks to about 1 hr. Smoking gradually decreased to the target level of about one-half of a package of cigarettes per day. Control procedures showed that specific features of the apparatus were responsible for the reduction of smoking. The results indicated that this apparatus was sufficiently effective, convenient, and acceptable to smokers to constitute a practical procedure for reducing smoking to the level considered medically safe. The procedure may also have potential for reducing other habit-forming or addictive behaviors.

Journal Article↗
PubMed1968

The effects of shock as a punisher for cigarette smoking.

An attempt was made to reduce the cigarette smoking of three subjects by means of a special cigarette case that delivered aversive shock when opened. The number of cigarettes smoked was recorded by a counter in the cigarette case. The validity of the counter readings as a measure of smoking was obtained by a specially designed participant-observer technique. It was found that the rate of smoking decreased as a function of the intensity of the shock. Also, the smoking returned to its previously unpunished level after the shock punisher was discontinued. Both of these findings confirm the results of laboratory studies of punishment of simpler responses and extends them to more complex responses in a naturalistic situation. Surprisingly, the duration for which the apparatus was worn also decreased as a function of the intensity of the shock. This finding reveals that this aversive shock technique produced avoidance behavior that prevents the technique from having extensive applicability for eliminating smoking. The same limitation may apply to the use of aversive shock for eliminating other undesirable behaviors.

Journal Article↗
PubMed1967

A rat chamber and electrode procedure for avoidance conditioning.

A method was developed for studying the reactions of rats to aversive shock. The distinctive features were the design of the chamber and a method of restraint that allowed the use of surface electrodes to deliver the shock. Advantages of this method were: (1) accurate specification of the shock actually received by the rat; (2) elimination of all unauthorized escape or avoidance reactions; (3) elimination of the shock scramblers and floor grids required with foot-shock; and, (4) rapid acquisition of performance under various avoidance procedures and various frequencies of shock delivery.

Animals↗
PubMed1966

Plaque enhancement of enteroviruses by magnesium chloride, cysteine, and pancreatin.

Wallis, Craig (Baylor University College of Medicine, Houston, Tex.), Fred Morales, Joycelyn Powell, and Joseph L. Melnick. Plaque enhancement of enteroviruses by magnesium chloride, cysteine, and pancreatin. J. Bacteriol. 91:1932-1935. 1966.-Plaque formation of 21 echoviruses (types 1-6, 9, 13, 15-19, 23-26, 29-32) and 8 coxsackieviruses (B1-6, A7, and A9) was enhanced by increased concentrations of MgCl(2), l-cysteine, and pancreatin in agar overlay medium. In most cases, cationic and anionic polymers (diethylaminoethyl dextran, dextran sulfate, or protamine sulfate) were ineffective. All strains of poliovirus and group B coxsackieviruses were enhanced under agar by MgCl(2). Five of the eight coxsackieviruses tested were also enhanced by cysteine or pancreatin. Certain enteroviruses, which have been difficult to assay by plaque method, can now be quantified effectively by incorporation of additives such as MgCl(2), cysteine, or pancreatin into the overlay medium.

Chlorides↗