Retention half times in the skeleton of plutonium and Sr-90 from above-ground nuclear tests: A retrospective study of the Swiss population

Plutonium and Sr-90 are considered to be among the most radiotoxic nuclides produced by the nuclear fission process. In spite of numerous studies on mammals and humans there is still no general agreement on the retention half time of both radionuclides in the skeleton in the general population. Here we determined plutonium and Sr-90 in human vertebrae in individuals deceased between 1960 and 2004 in Switzerland. Plutonium was measured by sensitive SF-ICP-MS techniques and Sr-90 by radiometric methods. We compared our results to the ones obtained for other environmental compartments to reveal the retention half time of NBT fallout Pu-239 and Sr-90 in trabecular bones of the Swiss population. Results show that plutonium has a retention half time of 40 +/- 14 years. In contrast Sr-90 has a shorter retention half time of 13.5 +/- 1.0 years. Moreover Sr-90 retention half time in vertebrae is shown to be linked to the retention half time in food and other environmental compartments. These findings demonstrate that the renewal of the vertebrae through calcium homeostatic control is faster for Sr-90 excretion than for plutonium excretion. The precise determination of the retention half time of plutonium in the skeleton will improve the biokinetic model of plutonium metabolism in humans. (C) 2010 Elsevier Ltd. All rights reserved.

Time of ruin in a risk model with generalized Erlang (n) interclaim times and a constant dividend barrier

In this paper we analyze the time of ruin in a risk process with the interclaim times being Erlang(n) distributed and a constant dividend barrier. We obtain an integro-differential equation for the Laplace Transform of the time of ruin. Explicit solutions for the moments of the time of ruin are presented when the individual claim amounts have a distribution with rational Laplace transform. Finally, some numerical results and a compare son with the classical risk model, with interclaim times following an exponential distribution, are given.

Sign of the Times, September-November 2012

Newsletter produced by Deaf Services Commission of Iowa

Life Times, Winter 2004

The IPERB newsletter is published by the Public Employment Relations Board. The opinions expressed should not be considered official opinions of the Iowa PERB.

Life Times, Winter 2005-2006

The IPERB newsletter is published by the Public Employment Relations Board. The opinions expressed should not be considered official opinions of the Iowa PERB.

Life Times, Winter 2008-2009

The IPERB newsletter is published by the Public Employment Relations Board. The opinions expressed should not be considered official opinions of the Iowa PERB.

Life Times, Winter 2007-2008

The IPERB newsletter is published by the Public Employment Relations Board. The opinions expressed should not be considered official opinions of the Iowa PERB.

Life Times, Summer 2007

The IPERB newsletter is published by the Public Employment Relations Board. The opinions expressed should not be considered official opinions of the Iowa PERB.

Life Times, Winter 2006-2007

The IPERB newsletter is published by the Public Employment Relations Board. The opinions expressed should not be considered official opinions of the Iowa PERB.

Life Times, Summer 2006

The IPERB newsletter is published by the Public Employment Relations Board. The opinions expressed should not be considered official opinions of the Iowa PERB.

Sign of the Times, December 2012-January 2013

Newsletter produced by Deaf Services Commission of Iowa

Relaxivity of Gd-based contrast agents on X nuclei with long intrinsic relaxation times in aqueous solutions.

The relaxivity of commercially available gadolinium (Gd)-based contrast agents was studied for X-nuclei resonances with long intrinsic relaxation times ranging from 6 s to several hundred seconds. Omniscan in pure 13C formic acid had a relaxivity of 2.9 mM(-1) s(-1), whereas its relaxivity on glutamate C1 and C5 in aqueous solution was approximately 0.5 mM(-1) s(-1). Both relaxivities allow the preparation of solutions with a predetermined short T1 and suggest that in vitro substantial sensitivity gains in their measurement can be achieved. 6Li has a long intrinsic relaxation time, on the order of several minutes, which was strongly affected by the contrast agents. Relaxivity ranged from approximately 0.1 mM(-1) s(-1) for Omniscan to 0.3 for Magnevist, whereas the relaxivity of Gd-DOTP was at 11 mM(-1) s(-1), which is two orders of magnitude higher. Overall, these experiments suggest that the presence of 0.1- to 10-microM contrast agents should be detectable, provided sufficient sensitivity is available, such as that afforded by hyperpolarization, recently introduced to in vivo imaging.

Sign of the Times, November 2013 - February 2014

Newsletter produced by Deaf Services Commission of Iowa