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Biomedical subjects

D Perkins

Publications and source records attributed to D Perkins.

53 records · Page 3Linked to original sources
PubMed1983

A refutation of the hypothesis of the superfidelity of caricatures relative to photographs.

The experiment was designed to test the hypothesis that caricatures, relative to photographs, are 'superfaithful' carriers of information for facial recognition. Subjects were shown fifteen picutres of people's faces and were then asked to pick those same people out of a set of fifty-four pictures. There were three sets of pictures: caricatures, profile-view photographs, and three-quarter-view photographs. There were nine groups of subjecs: for three groups the exposure and test stimuli were in the same medium, for six groups the test stimuli were in one of the media not previously seen. Points were scored for the number of people correctly identified and the number of false positives. Facial recognition within medium was very good, but was seriously disrupted by any medium shift, especially those involving caricatures. It is argued that the superfidelity of caricature may be manifest only when the task involves recognition of actual persons rather than their pictures.

Face↗
PubMed1981

Medical student attitudes toward geriatric medicine and patients.

This study examines the influence of factual knowledge of the aged, general attitudes toward the aged, and personal contact with the aged on first-year medical students' attitudes toward geriatric patients and geriatric medicine. Entering medical students indicated a preference for working with younger patients rather than aged patients. Students' attitudes toward the aged were associated positively with their knowledge of the aged, but their interest in geriatric medicine did not appear to be affected significantly by knowledge of, attitudes toward, or personal contact with the aged. The results suggest that factors beyond those considered in this study may need to be examined if there is to be an increase in the number of physicians wishing to care for the elderly.

Aged↗
PubMed1980

Fluoride resistance and adherence of selected strains of Streptococcus mutans to smooth surfaces after exposure to fluoride.

The fluoride resistance and smooth surface adherence characteristics of Streptococcus mutans were examined using tooth model and radioactive cell assays. Resistance to 600 ppmF by S. mutans isolated from the plaque of radiation-induced xerostomia patients receiving daily topical applications of a caries preventive 1% NaF gel was transient. Resistance induced in vitro in two strains of S. mutans by exposure to gradually increasing levels of NaF was apparently permanent. Smooth surface adherence by both fluoride-sensitive and -resistant strains of S. mutans 6715 in a tooth model system was slightly diminished by 1% NaF gel. Fluoride-resistant strains retained 89 to 93% of their adherence capability in 600 ppmF, as determined by the cell radiolabeling assay.

Adhesiveness↗
PubMed1980

Choice of timeout during response-independent food schedules.

Rats' lever pressing terminated visual or auditory stimuli associated with fixed-time or variable-time schedules of food delivery and produced a timeout period during which food delivery could not occur. Lever pressing during a timeout period reinstated the food-associated stimuli and again permitted food delivery according to the fixed-time or variable-time schedules. The mean interfood interval ranged from 1 minute to 16 minutes (variable-time schedules) or 32 minutes (fixed-time schedules); the timer controlling schedule intervals did not stop during timeout periods. The percentage of session time spent in timeout increased when the mean interfood intervals were lengthened and decreased when the mean interfood intervals were shortened. Timeouts were initiated most frequently about half way between successive food deliveries (fixed-time schedules) or after 15 seconds or more had lapsed since the last food delivery (variable-time schedules). Elimination of food delivery increased the percentage of session time spent in timeout, and elimination of the timeout contingency decreased lever press rates. When timeout was produced only when the lever was held in the depressed position, little time was spent in timeout. The main determinants of timeout initiation and termination appeared to be the rate of food delivery, freedom of movement during timeout, and the stimulus change associated with initiation and termination of timeout.

Journal Article↗
PubMed1978

Pathogenesis of papain-induced emphysema in the hamster.

In an effort to determine the mechanism of papain action in causing an emphysema-like lesion in hamsters, the number and types of cells and the activities of two lysosomal enzymes in the lung were determined after papain exposure. Three and four weeks after a 3-h exposure to an aerosol of 3% papain the following alterations in lung structure and function were observed: (1) the mean linear intercept, or average distance between adjacent alveoli, was increased; (2) the internal surface area declined; (3) the dynamic compliance was elevated at low breathing frequencies. The numbers of cells present free in the lung increased from a control value of 2.0 +/- 0.2 x 10 (6) to 6.6 +/- 0.5 x 10 (6) 5 days after exposure. The free beta-glucuronidase, alysosomal enzyme, likewise increased over threefold during the first 3 days after exposure. These results are consistent with the hypothesis that papain induces an inflammatory-type responses, and this may be in part responsible for inducing the lesion.

Animals↗
PubMed1977

Mammary tuberculosis: a rare modern disease.

Tuberculosis of the breast has become a rare disease since the advent of antituberculous chemotherapy. The incidence of tuberculous mastitis at Vanderbilt Hospital for the last two decades was 0.025% of surgically treated breast disease. This probably reflects its prevalence in economically developed parts of the world. The pathologic diagnosis of mammary tuberculosis may be difficult. The only diagnostic proof is the demonstration of tubercle bacilli by microscopic smear of culture. Numerous cases have been incorrectly reported as mammary tuberculosis because of nonadherence to this criterion. Definite guidelines for treating breast tuberculosis are not available and may never become so because of its rarity. Drug therapy has been successful and should be tried in all cases. Adequate surgical removal is inevitably corrective of the local disease. Surgically treated patients should receive antituberculous drugs before and after their operations.

Adult↗
PubMed1977

Effects of fixed-ratio sample and choice response requirements upon oddity matching.

Three pigeons were trained on oddity matching in which either 1, 4, 8, 16, or 32 sample-key observing responses were required to turn off the sample stimuli and turn on the comparison stimuli. Oddity accuracy increased when the observing-response requirement was raised and decreased when the requirement was lowered. Next, while the observing requirement was maintained at one response, the number of responses required to the comparison stimuli was either 1, 4, 8, 16, or 32. Under these conditions, choice was defined as the comparison that first accumulated the required number of responses. In general, increasing the comparison-response requirement decreased accuracy and lowering the comparison requirement increased accuracy. The fixed-ratio observing requirements appeared to facilitate control by stimuli serving an instructional function.

Journal Article↗
PubMed1974

Effects of response-produced stimuli upon conditional discrimination performance.

In zero-delay matching procedures the performance of three groups of pigeons was examined when exteroceptive stimuli, response-produced stimuli associated with the completion of either of two fixed ratios, or a compound of exteroceptive and response-produced stimuli were available as samples. Exteroceptive samples were found to control a higher level of matching accuracy than response-produced samples, while compound samples controlled a higher level of accuracy than did exteroceptive samples alone. When all subjects were placed on a transfer procedure, during which the previously used red and green samples were replaced by horizontal and vertical lines, the availability of sample-specific fixed-ratios facilitated acquisition of the task.

Journal Article↗
PubMed1969

Fauna of Catal Hüyük: evidence for early cattle domestication in Anatolia.

Analysis of the remains of cattle from Catal Hüyük indicates that cattle were domesticated in Anatolia by 5800 B.C., and strongly suggests that they were probably domestic at least 500 years earlier. This is the earliest known evidence for the domestication of cattle in the Near East.

Age Determination by Skeleton↗
PubMedDate not supplied

Careers: to be forgotten or managed?

Managers need new skills to plan their own careers and health services organisations will benefit from attending to the career opportunities available to their staff, according to Dr Alison Baker and Dr David Perkins.

Administrative Personnel↗