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K O'Brien

Publications and source records attributed to K O'Brien.

At least 145 records · Page 8Linked to original sources
PubMed1977

Monte Carlo calculations of the energy response of lithium dosemeters to high energy electrons (less than 30 MeV).

Monte Carlo calculations of the energy response of LiF dosemeters have been carried out to help resolve the discrepancy between the measurements of Holt, Edelstein and Clark (1975) and those of Paliwal and Almond (1975) and others. It is concluded that the assumptions used by Holt et al. are largely responsible. They assume, in converting energy deposition in an air-filled ionization chamber to energy deposition in water, that as electrons penetrate a medium they are monoenergetic and the energy is given by Harder's expression (ICRU 1972). The assumption gives poor results as the stopping power for electrons in air is strongly energy dependent, and the energy spectrum has been significantly broadened. The Monte Carlo calculations are also used to criticize the electron cavity theories of Almond and McCray (1970), Burlin, Snelling and Owen (1969) and Holt et al. (1975), and to suggest as an alternative a slightly modified version of the Bragg-Gray theorem.

Electrons↗
PubMed1976

Ebstein's anomaly. Genetic study of 26 families.

The families of 26 patients with Ebstein's anomaly were examined. There were 120 first-degree relatives, 100 of whom were living, and 93 of these were examined. Information was available on 14 of the 20 who had died. No case of Ebstein's anomaly was found among the first-degree relatives, but 2 had ventricular septal defects and another, who died at 7 months, was said to have had congenital heart disease. In more distant relatives there were 6 with congenital heart disease, including 2 with ventricular septal defects and 2 with Fallot's tetralogy.

Ebstein Anomaly↗
PubMed1976

Long-term hemodialysis for patients over 50.

Hemodialysis can hodl end-state renal failure at bay and enable patients to lead a relatively normal life-regardless of their age. In a 10 year retrospective study of 574 patients, the 154 patients over 50 had about the same survival rates as younger persons for the first three years of dialysis. After that, the older patients had higher mortality. Patients who dialyzed themselves at home-with a relative or friend to help-had much better results than those who were dialyzed at the center. This in part reflects the selection process, since patients with severe medical problems usually weren't allowed to try self-dialysis. Older patients did particularly well on home dialysis, which was attributed to their maturity and dependability. Older patients with cardiac instability may require carefully monitored dialysis at the center and frequent blood transfusions. In general, though, patients over 50 needed fewer transfusions and fewer days in the hospital than younger patients.

Aged↗
PubMed1975

Association of secundum atrial septal defect with abnormalities of atrioventricular conduction or left axis deviation. Genetic study of 10 families.

A genetic analysis was made of 10 families in which the propositi had a secundum atrial septal defect associated with abnormal atrioventricular conduction (first, second, or third degree heart block) or unexplained left axis deviation or a combination of these conduction disturbances. Diagnostic information was available on 51 (81%) of the first degree relatives. Three of the families appeared to be examples of a new syndrome which, with variable expression, was inherited as a non-sex-linked autosomal dominant. The main features were a secundum atrial septal defect; disease of the conducting tissue, which in some cases was progressive; unexplained left axis deviation; and unexpected death. These families did not seem to be examples of the Holt-Oram syndrome, for the upper limbs were clinically and radiologically normal in the 19 members examined. The importance of recognizing this syndrome is the occurrence of progressive disease of the conducting tissue and the risk of sudden death. When, therefore, unexplained left axis deviation or prolonged atrioventricular conduction is found in association with a secundum atrial septal defect all available relatives should be examined. In the remaining seven families there was only one affected first degree relative out of 39 examined. He was the son of one of the propositi and had paroxysmal coronary sinus rhythm with an intact atrial septum.

Adolescent↗