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Biomedical subjects

J E Powers

Publications and source records attributed to J E Powers.

7 recordsLinked to original sources
PubMed1991

Solitary retinal astrocytoma.

Astrocytic hamartomas are typically white, well-circumscribed, elevated lesions arising in single or multiple areas of the retina and epi- or peripapillary optic nerve. These lesions are most commonly associated with tuberous sclerosis and less commonly associated with neurofibromatosis. However, solitary retinal or optic nerve astrocytomas can be found in normal individuals. This paper reviews the case of a 48-year-old white female who presented with a solitary retinal astrocytoma of the right eye, without any other physical or ocular disorder. The histopathological and clinical appearance and course of astrocytomas, its differential diagnosis from other retinal and optic nerve lesions, and its association with tuberous sclerosis are discussed.

Astrocytoma↗
PubMed1982

Evaluating Doppler devices using a moving string test target.

Two moving string test targets have been developed and used to characterize ultrasound Doppler instrumentation. The characteristics investigated were sample volume size and location in space, amplitude sensitivity to Doppler shift, and resolution of Doppler direction. The tests were performed on a combined echo/Doppler instrument and on an annular array system. The procedures can be carried out routinely in the clinical laboratory to ensure that the instrument is working properly or as an aid for correct interpretation of acquired data.

Auscultation↗
PubMed1979

Reliability and validity of the Group Embedded Figures Test for a grade school sample.

Data on validity of the Group Embedded Figures Test for 22 sixth grade students (9 boys and 13 girls) were obtained. 50 wk. later all subjects were individually screened on the Portable Rod-and-Frame Test and after a period of 2 more weeks, when they were retested on the embedded figures, data on reliability were obtained. Long-term coefficients of stability of .80 and .71 for the 9 boys and 13 girls, respectively, were obtained. Coefficients of internal consistency ranged from .83 to .98 for boys and girls. Coefficients reflecting both construct and concurrent validity were -.60 and .00 for boys and girls, respectively. Customary sex differences with respect to field-dependence--independence were not observed for these small samples.

Child↗
PubMed1977

Field dependence--independence and performance with the passive transformation.

An investigation of the influence of children's levels of field dependence-independence on their performance with the passive transformation is presented. Eighty 6th graders classified as field dependent or field independent were presented with sentence-question combinations, each in either the active or passive voice, and numbers of correct responses were recorded. Results showed that field-independent subjects performed better over-all than did field-dependent subjects. The three-way interaction of field dependence-independence, sentence voice, and question voice was also significant. Field-dependent subjects performed significantly more poorly on the active-passive and passive-active combinations than on the active-active and passive-passive combinations. There were no significant differences among the four treatments within the field-independent subjects. Thus field-dependent subjects had greatest difficulty with combinations requiring them to isolate the essential elements of a sentence and use them in a different form; field-independent subjects did not experience this difficulty.

Aptitude↗