Mjerenje radona u vodi radi predviđanja potresa u Sloveniji

Radon (222Rn) concentration in water of several thermal springs was measured with the aim of obtaining a correlation with the seismic activity of the region. Though a qualitative correlation was found for a spring with deep water circulation, we are far from being able to predict either the time or the place of an earthquake. An additional study with more relevant sampling sites and more frequent water analyses would be necessary to achieve this.Mjerili smo količinu radona (222Rn) u vodi iz više izvora radi utvrđivanja moguće korelacije sa seizmičkom aktivnosti u Sloveniji. Iako smo našli kvalitativnu korelaciju za jedan izvor s dubokim kruženjem vode, nismo još u mogućnosti predvidjeti mjesto ili vrijeme potresa. Za to su potrebna proširena mjerenja na više mjesta i sa češćim uzorkovanjem vode

Dependence of radon levels in Postojna Cave on outside air temperature

Postojna Cave is the largest of 21 show caves in Slovenia. The radon concentration there was measured continuously in the Great Mountain hall from July 2005 to October 2009 and ranged from about 200 Bq m<sup>−3</sup> in winter to about 3 kBq m<sup>−3</sup> in summer. The observed seasonal pattern of radon concentration is governed by air movement due to the difference in external and internal air densities, controlled mainly by air temperature. The cave behaves as a large chimney and in the cold period, the warmer cave air is released vertically through cracks and fissures to the colder outside atmosphere, enabling the inflow of fresh air with low radon levels. In summer the ventilation is minimal or reversed and the air flows from the higher to the lower openings of the cave. Our calculations have shown that the effect of the difference between outside and cave air temperatures on radon concentration is delayed for four days, presumably because of the distance of the measurement point from the lower entrance (ca. 2 km). A model developed for predicting radon concentration on the basis of outside air temperature has been checked and found to be successful

Re-entrant ferroelectricity in liquid crystals

The ferroelectric (Sm C$^*$) -- antiferroelectric (Sm C$^*_A$) -- reentrant ferroelectric (re Sm C$^*$) phase temperature sequence was observed for system with competing synclinic - anticlinic interactions. The basic properties of this system are as follows (1) the Sm C$^*$ phase is metastable in temperature range of the Sm C$^*_A$ stability (2) the double inversions of the helix handedness at Sm C$^*$ -- Sm C$^*_A$ and Sm C$^*_A$% -- re-Sm C$^*$ phase transitions were found (3) the threshold electric field that is necessary to induce synclinic ordering in the Sm C$^*_A$ phase decreases near both Sm C$^*_A$ -- Sm C$^*$ and Sm C$^*_A$ -- re-Sm C$^*$ phase boundaries, and it has maximum in the middle of the Sm C$^*_A$ stability region. All these properties are properly described by simple Landau model that accounts for nearest neighboring layer steric interactions and quadrupolar ordering only.Comment: 10 pages, 5 figures, submitted to PR

EFFECTIVE DOSE FOR REAL POPULATION EXPOSED TO INDOOR RADON IN DWELLINGS OF THE FORMER URANIUM MINE AREA KALNA (EASTERN SERBIA)

This paper deals with calculated effective doses that members of real population received from radon gas and its short lived progeny during air inhalation in their dwellings at field site Kalna in Eastern Serbia. There are two crucial parameters in effective dose calculation: Dose Conversion Factor (DCF) for particular subjects (including real gender, age and physical activity level) and indoor concentration of radon and its short lived progeny in field area. According to the results of indoor radon measurements in the area of former uranium mine, Kalna, the effective dose for this real population was estimated by using the dosimetric lung model, developed by authors according ICRP Publication 66. Authentic software was developed for determination of effective dose per unit inhaled activity of radon progeny, DCF expressed in unit [mSv/WLM]. The results, obtained according to ICRP 66 dosimeter lung model, were compared with results calculated according to ICRP Publication 65. The dosimetric results were, also, compared and discussed with epidemiological approach data, according to UNSCEAR

The peculiarities of cross-correlation between two secondary precursors - radon and magnetic field variations, induced by stress transfer changes

A model of precursor manifestation mechanisms, stimulated by tectonic activity and some peculiarities of observer strategy, whose main task is the effective measurement of precursors in the spatial area of their occurrence on the Earth's daylight, are considered. In particular, the applicability of Dobrovolsky's approximation is analyzed, when an unperturbed medium (characterized by the simple shear state) and the area of tectonic activity (local inhomogeneity caused by the change only of shear modulus) are linearly elastic, and perturbation, in particular, surface displacement is calculated as a difference of the solutions of two independent static problems of the theory of elasticity with the same boundary condition on the surface. Within the framework of this approximation a formula for the spatial distribution (of first component) of magnetic field variations caused by piezomagnetic effect in the case of perturbed regular medium, which is in simple shear state is derived. Cogent arguments in favor of linear dependence between the radon spatial distribution and conditional deformation are obtained. Changes in magnetic field strength and radon concentrations were measured along a tectonomagnetic profile of the total length of 11 km in the surroundings of the "Academician Vernadsky" Station on the Antarctic Peninsula (W 64{\deg}16', S 65{\deg}15'). Results showed a positive correlation between the annual surface radon concentration and annual changes of magnetic field relative to a base point, and also the good coincidence with theoretical calculation.Comment: 27 pages, 11 figures, 3 tables (a substantially revised and extended edition; v3 -- some analysis of recent publications added

Molecular simulation of chevrons in confined smectic liquid crystals

Chevron structures adopted by confined smectic liquid crystals are investigated via molecular dynamics simulations of the Gay-Berne model. The chevrons are formed by quenching nematic films confined between aligning planar substrates whose easy axes have opposing azimuthal components. When the substrates are perfectly smooth, the chevron formed migrates rapidly towards one of the confining walls to yield a tilted layer structure. However, when substrate roughness is included, by introducing a small-amplitude modulation to the particle- substrate interaction well-depth, a symmetric chevron is formed which remains stable over sufficiently long runtimes for detailed structural information, such as the relevant order parameters and director orien- tation, to be determined. For both smooth and rough boundaries, the smectic order parameter remains non-zero across the entire chevron, implying that layer identity is maintained across the chevron tip. Also, when the surface-stabilised chevron does eventually revert to a tilted layer structure, it does so via surface slippage, such that layer integrity is maintained throughout the chevron to tilted layer relaxation process. </p

Slovenian approach in managing exposure to radon at workplaces

Radon was surveyed in all the kindergartens and schools, major hospitals, water plants, wineries, spas, in a number of other public buildings, and karst caves with emphasis on the Postojna Cave (Slovenia). In addition to radon, also the concentration of radon short-lived decay products, equilibrium factor between radon and decay products, and unattached fraction of decay products have been monitored. Effective doses were calculated and used as a criterion to require remediation