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Biomedical subjects

P S Singh

Publications and source records attributed to P S Singh.

9 recordsLinked to original sources
PubMed2000

A study of energy and effective atomic number dependence of the exposure build-up factors in biological samples.

A theoretical method is presented to determine the gamma-radiation build-up factors in various biological materials. The gamma energy range is 0.015-15.0 MeV, with penetration depths up to 40 mean free paths considered. The dependence of the exposure build-up factor on incident photon energy and the effective atomic number (Zeff) has also been assessed. In a practical analysis of dose burden to gamma-irradiated biological materials, the sophistication of Monte Carlo computer techniques would be applied, with associated detailed modelling. However, a feature of the theoretical method presented is its ability to make the consequences of the physics of the scattering process in biological materials more transparent. In addition, it can be quickly employed to give a first-pass dose estimate prior to a more detailed computer study.

Models, Biological↗
PubMed1991

Prevalence & spectrum of congenital malformations in a prospective study at a teaching hospital.

A prospective survey for congenital malformations at birth, at a teaching hospital, over a period of two and half years on 9405 consecutive single births has shown that prevalence of major congenital malformations in live births was 1.6 per cent and in still births 16.4 per cent. There was no significant difference in the prevalence of congenital malformations between Hindus (2.0%) and Muslims (2.7%) but amongst Muslims with consanguinity the prevalence of congenital malformation was 4.6 per cent compared to 2.3 per cent in non-consanguineous Muslim spouses (P less than 0.05). Open neural tube defect was the single most common anomaly (31.7% of all malformations) occurring at a rate of 4.7 per 1000 single births, with equal prevalence of anencephaly and meningomyelocoele. Case control study showed that history of concomitant medical illness, drug intake during the first trimester, threatened abortion, hydramnios and pre-eclamptic toxaemia in the current pregnancy were significantly associated with the occurrence of congenital malformations.

Congenital Abnormalities↗