Dissipation in ferrofluids: Mesoscopic versus hydrodynamic theory

Part of the field dependent dissipation in ferrofluids occurs due to the rotational motion of the ferromagnetic grains relative to the viscous flow of the carrier fluid. The classical theoretical description due to Shliomis uses a mesoscopic treatment of the particle motion to derive a relaxation equation for the non-equilibrium part of the magnetization. Complementary, the hydrodynamic approach of Liu involves only macroscopic quantities and results in dissipative Maxwell equations for the magnetic fields in the ferrofluid. Different stress tensors and constitutive equations lead to deviating theoretical predictions in those situations, where the magnetic relaxation processes cannot be considered instantaneous on the hydrodynamic time scale. We quantify these differences for two situations of experimental relevance namely a resting fluid in an oscillating oblique field and the damping of parametrically excited surface waves. The possibilities of an experimental differentiation between the two theoretical approaches is discussed.Comment: 14 pages, 2 figures, to appear in PR

A Screening Study of Thyroid Cancer and Other Thyroid Diseases among Individuals Exposed in Utero to Iodine-131 from Chernobyl Fallout

Background: Like stable iodine, radioiodines concentrate in the thyroid gland, increasing thyroid cancer risk in exposed children. Data on exposure to the embryonic/fetal thyroid are rare, raising questions about use of iodine 131 (I-131) in pregnant women. We present here estimated risks of thyroid disease from exposure in utero to I-131 fallout from the Chernobyl nuclear accident

ENSURING OF RADIATION PROTECTION DURING WORKS ON TRANSFORMATION OF THE OBJECT SHELTER INTO ECOLOGICALLY SAFE SYSTEM. BIOPHYSICAL MONITORING OF THE PERSONNEL INTERNAL EXPOSURE DOSES

Given paper, states the ensuring of the interpretation of the basic radiation protection principles, relative to the works at the Object Shelter (OS). Analysis of the factors of radiation situation at the OS is figured out. Functioning at the present time individual dose monitoring (IDM) system at the OS is describe. The system is based on the methods of biophysical monitoring. A series of the results, obtained during internal exposure individual dose monitoring of the personnel is presented. It is mentioned, that implementation of the internal exposure dose biophysical monitoring system (during the works on transformation of the OS into ecologically safe system) allows:  provide adequate level of the IDM of the internal exposure dose (the level is corresponds to the present day requirements of the radiation protection); develop the recommendations on selection of individual means of protection of respiratory tract; ensure determination of the parameters of radioactive air contamination in the work areas; and, provide the optimal planning of dose load to the personnel

Review of methods and computer codes for interpretation of bioassay data

International audienc

The work of the CONRAD task group 5.2: Research studies on biokinetic models

The objective of this Task Group is the coordination of research studies on biokinetic models and the evaluation of the implications of new biokinetic models on dose assessment and safety standards. For this the new ICRP models, which will be used for a revision of ICRP Publications 30, 54, 68 and 78, are implemented into six different computer codes in five European countries and quality assured by intercomparison procedures. The work has started with the implementation of the new ICRP Alimentary Tract Model. New systemic models and the new NCRP wound model will follow. The work also includes the evaluation of experimental results in terms of formulation by the new model structures and a quality assurance of model formulation. © The Author 2007. Published by Oxford University Press. All rights reserved