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Biomedical subjects

D M Hawkins

Publications and source records attributed to D M Hawkins.

28 records · Page 2Linked to original sources
PubMed1976

Effects of breast-feeding practice on the post-partum endometrium.

Inactive endometrial patterns occur frequently in the post-partum period and their occurrence is modified by the breast-feeding practice. An abnormal endometrium pattern, viz., cystic hyperplasia, may occur more frequently in non-lactating women and in patients using oestrogens, especially long-acting preparations, for lactation suppression. Post-ovulatory endometrial patterns in lactating women occur infrequently during the puerperium. The implications of these findings are discussed.

Adult↗
PubMed1975

Epidemiology of rheumatic heart disease in black shcoolchildren of Soweto, Johannesburg.

A survey to determine the prevalence of rheumatic heart disease (R.H.D.) in Black children was conducted in the creeches and primary schools of the South Western Townships of Johannesburg (Soweto). A total of 12 050 Black children were examined by 10 cardiologists in May to October 1972. The overal prevalence rate of R.H.D. was 6.9 per 1000, with a peak rate of 19.2 per 1000 in children of the seventh school grade. The maximal age incidence was 15-18 years and there was a female preponderance of 1 6:1. A rise in prevalence occurred with increasing family size. Most children (92%) were asymptomatic, and in 82.5% R.H.D. was diagnosed for the first time during the school survey. The commonest valve lesion was mitral regurgitation, which was present in 93% and occurred as an isolated lesion in 47.5%. Lancefield's group A beta-haemolytic streptococcus was isolated from the throats of 52 per 1000 Soweto children. The auscultatory features of a non-ejection systolic click and late systolic murmur were prevalent (13.9 per 1000) and had several epidemiological factors in common with R.H.D. A comprehensive preventative campaign is urgently needed in South Africa, directed at both primary and secondary prophylaxis of R.H.D. The socioeconomic status of the community must be improved if optimal prevention is to be achieved.

Adolescent↗
PubMedDate not supplied

QSAR with few compounds and many features.

Fitting quantitative structure-activity relationships (QSAR) requires different statistical methodologies and, to some degree, philosophies depending on the "shape" of the data matrix. When few features are used and there are many compounds, it is a reasonable expectation that good feature subset selection may be made and that nonlinearities and nonadditivities can be detected and diagnosed. Where there are many features and few compounds, this is unrealistic. Methods such as ridge regression RR, PLS, and principal component regression PCR, which abjure feature selection and rely on linearity may provide good predictions and fair understanding. We report a development of ridge regression for the underdetermined case by using generalized cross-validation to choose the ridge constant and perform F-tests for additional information. Conventional regression diagnostics can be used in followup to identify nonlinearities and other departures from model. We illustrate the approach with QSAR models of four data sets using calculated molecular descriptors.

Algorithms↗