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D T Freeman
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ABSTRACT: A neural network simulator was used to create a connectionist model for the recognition of the peak of wave V of the brain stem auditory evoked potential (BAEP) test. Wave forms were selected from BAEPs performed in the last four years at the University of Pittsburgh Presbyterian University Hospital (PUH). The ipsilateral and contralateral wave forms were digitized and then sampled at 0.1 msec intervals using linear interpolation. The resulting amplitudes were normalized to the range less than -1, 1 greater than. The normalized amplitudes were used as the initial activation values for the processing elements of the input layer. The desired outputs (the target locations for wave V) were determined by adjusting the latencies recorded by the physician interpreter for any distortion in the digitizing process. The location of wave V was represented in the output layer by setting the output element which correspond to the target location and its immediate neighbors to high activation levels and all the remaining output units to zero activity. Two network architectures, differing only in the hidden unit layer, with 40 and 16 hidden units respectively, were used. The networks were trained using standard back-propagation. Several trials from different starting points were performed for each architecture. The training set was composed of the wave forms resulting from the stimulation of 50 ears. The best network, found after 60 epochs (3000 presentations) was able to correctly identify 17 out of 20 cases (85%) from a set of test cases which were independent from the training set.
Proceedings / the ... Annual Symposium on Computer Application [sic] in Medical Care. Symposium on Computer Applications in Medical Care 02/1991;
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ABSTRACT: This cross-sectional study of urban, Nigerian civil servants found that age, body mass index, alcohol drinking and high socioeconomic status were all positively and independently related to blood pressure among 438 males. Among 121 females, only body mass index was significantly related to blood pressure.
Journal of Human Hypertension 05/1990; 4(2):82-4. · 2.80 Impact Factor
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ABSTRACT: In this study, we examined the relationship of two common genetic markers in black populations, sickle cell trait and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, to cardiovascular risk factors. The subjects were Nigerian civil servants in Benin City, Nigeria. We measured blood pressure, height, weight, sickle cell hemoglobin, G-6-PD, proteinuria, microalbuminuria and fasting serum cholesterol, high-density lipoprotein cholesterol (HDL), triglycerides, apoprotein (APO) AI, and APO B. Data were collected on age, alcohol consumption, cigarette smoking, job status, and years lived in an urban area. There were 257 males (3 SS hemoglobin, 73 AS, 181 AA) and 69 females (23 AS, 46 AA). In comparing cardiovascular risk factors, males differed only in percent of smokers (31.5 in AS vs. 17.8 in AA, P less than 0.01). Among females, only high-density lipoprotein (HDL) cholesterol differed (61.5 mg/dl in AS vs. 52.4 in AA, P less than 0.01). We hypothesize that females with sickle cell trait are more likely to use oral contraceptives than nontrait females. If so, the high-estrogen oral contraceptives available in Nigeria could elevate HDL. G-6-PD deficiency status among males (52 deficient, 207 nondeficient) and females (1 deficient, 5 carriers, 65 nondeficient) was not related to any of the cardiovascular risk factors. We conclude that sickle cell hemoglobin trait and G-6-PD deficiency are not useful genetic markers for risk factors for cardiovascular disease.
Genetic Epidemiology 02/1990; 7(3):211-8. · 3.44 Impact Factor
