Aircrew dosimetry by means of experimental measurements and calculations: results obtained during the year 2003.

The results of measurements performed during the year 2003 onboard aircraft, mostly during regular commercial flights of the Czech Airlines (CSA) are presented. The studies were performed during more than 30 individual flights, several dosemeters and equipments were used for both neutron and non-neutron components of the onboard radiation field. CSA colleagues submitted us for all flights with navigation data necessary for the calculation of onboard aircraft crew exposure with transport codes EPCARD and CARI.

Radiation affects binding of Fpg repair protein to an abasic site containing DNA.

During the base excision repair of certain DNA lesions, the formamidopyrimidine-DNA glycosylase (Fpg) binds specifically to the DNA region containing an abasic (AP) site. Is this step affected by exposure to ionizing radiation? To answer this question, we studied a complex between a DNA duplex containing an analogue of an abasic site (the 1,3-propanediol site, Pr) and a mutated Lactococcus lactis Fpg (P1G-LlFpg) lacking strand cleavage activity. Upon irradiation of the complex, the ratio of bound/free partners decreased.

DNA radiolysis in DNA-protein complexes: a stochastic simulation of attack by hydroxyl radicals.

Purpose: To propose an improved version of RADACK, a stochastic simulation of radiolytic attack on DNA, that takes into account the reactivity of each amino acid of a specifically bound protein with hydroxyl radicals. To apply it to the natural lactose operator-repressor complex taking advantage of recently reported structures. To compare the obtained probabilities of DNA strand break induction with those calculated with the previous versions and with an experimental pattern of strand break probabilities.

Stochastic simulation of gamma radiolysis of acidic ferrous sulfate solution at elevated temperatures.

The effect of temperature on the oxidation of Fe2+ in the gamma radiolysis of acidic ferrous sulfate solutions has been modelled using the stochastic IRT method, incorporating simulated electron track structures. There is an 11% increase in the Fe3+ yield in aerated 0.4 M H2SO4 solution on going from 298 to 573 K (25 to 300 degrees C).

Microdosimetric characteristics of the clinical proton beams at JINR, Dubna.

High-energy proton radiotherapy beams give rise to secondary heavy charged particles with elevated linear energy transfer (LET), which contribute to the dose in a patient. This contribution to the characteristics of radiotherapy proton beams was experimentally studied by means of a LET spectrometer based on a track detector. The spectrometer permits LET spectra to be established in the region above 10 keV.