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Simple methods for calculating activity of a parent-progeny system.

ABSTRACT: Based on the original work of Rutherford (Radio-activity, 1905) and Bateman (Proc Camb Philos Soc 15:423-427, 1910), the authors designed two schemes consisting of explicit equations as simple methods for accurately obtaining activity of 90Sr and 90Y before they reach secular equilibrium. Application of the methods to the 90Sr/90Y system where 90Sr and 90Y are not in equilibrium will substantially reduce the time needed for determining activity of 90Sr because neither sequential measurements of 90Sr or 90Y (up to about 2 weeks) nor waiting for 90Sr and 90Y to reach equilibrium (more than 3 weeks) will be needed. We also implemented the explicit equations for decay/ingrowth correction of progeny's activity and applied them to the 95Zr/95Nb system. Using the equations, the authors corrected activity concentrations of 95Nb to a designated reference time from the activity concentrations measured from samples at different times, for instance, 2, 8, 15, and 29 days after a reference time. During those measurement times, 95Nb and 95Zr were not in equilibrium. The corrected 95Nb activity concentrations were within an accuracy of - 10%.

SUBMITTER: Wei C

PROVIDER: S-EPMC6980259 | biostudies-literature | 2019 Sep

REPOSITORIES: biostudies-literature

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Simple methods for calculating activity of a parent-progeny system.

Wei Cong C Garnick Kelly K Scott Thomas T Wetherby Anthony A

Journal of radioanalytical and nuclear chemistry 20190901 2

Based on the original work of Rutherford (Radio-activity, 1905) and Bateman (Proc Camb Philos Soc 15:423-427, 1910), the authors designed two schemes consisting of explicit equations as simple methods for accurately obtaining activity of 90Sr and 90Y before they reach secular equilibrium. Application of the methods to the 90Sr/90Y system where 90Sr and 90Y are not in equilibrium will substantially reduce the time needed for determ ...[more]

PMID: 31983798

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Project description:BACKGROUND:Symptom clusters are conventionally distilled into a single score using composite scoring, which is based on the mathematical assumption that all symptoms are equivalently related to outcomes of interest; this may lead to a loss of important variation in the data. OBJECTIVES:This article compares two ways of calculating a single score for a symptom cluster: a conventional, hypothesis-driven composite score versus a data-driven, reduced rank regression score that weights the symptoms based on their individual relationships with key outcomes. METHODS:We conducted a secondary analysis of psychoneurological symptoms from a sample of 356 low-income mothers. Four of the psychoneurological symptoms (fatigue, cognitive dysfunction, sleep disturbance, and depressed mood) were measured with the Center for Epidemiological Studies Depression Scale; the fifth (pain) was measured using an item from the Medical Outcomes Study 12-item Short Form Health Survey (SF-12). Mothers' function was measured using the 12-item Short Form Health Survey. The composite score was calculated by summing standardized scores for each individual psychoneurological symptom. In contrast, reduced rank regression weighted the individual symptoms using their respective associations with mothers' function; the weighted individual symptom scores were summed into the reduced rank regression symptom score. RESULTS:The composite score and reduced rank regression score were highly correlated at .93. The cluster of psychoneurological symptoms accounted for 53.7% of the variation in the mothers' function. Depressed mood and pain accounted for almost all the explained variation in mothers' function at 37.2% and 15.0%, respectively. DISCUSSION:The composite score approach was simpler to calculate, and the high correlation with the reduced rank regression score indicates that the composite score reflected most of the variation explained by the reduced rank regression approach in this data set. However, the reduced rank regression analysis provided additional information by identifying pain and depressed mood as having the strongest association with a mother's function, which has implications for understanding which symptoms to target in future interventions. Future studies should also explore composite versus reduced rank regression approaches given that reduced rank regression may yield different insights in other data sets.

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Simple methods for calculating activity of a parent-progeny system.

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Simple methods for calculating activity of a parent-progeny system.

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