Time filter

Source Type

Yaroshevich M.I.,Research and Production Association Typhoon
Izvestiya - Atmospheric and Ocean Physics | Year: 2016

It is especially important to know the character and the intensity level of tropical cyclone (TC) activity when the system for estimating the cyclonic danger and risk is formed. During seasons of increased cyclonic activity, when several TCs are simultaneously active, the total energy effect of the cyclone group joint action is not estimated numerically. Cyclonic activity is as a rule characterized by the number of TCs that occur in the considered zone. A variant of the criterion, according to which relative cyclonic activity is estimated, is presented. © 2016, Pleiades Publishing, Ltd.

Vives I Batlle J.,Belgian Nuclear Research Center | Sazykina T.G.,Research and Production Association Typhoon | Kryshev A.,Research and Production Association Typhoon | Monte L.,ENEA | Kawaguchi I.,Japan National Institute of Radiological Sciences
Radiation and Environmental Biophysics | Year: 2012

An inter-comparison of five models designed to predict the effect of ionizing radiation on populations of non-human wildlife, performed under the IAEA EMRAS II programme, is presented and discussed. A benchmark scenario 'Population response to chronic irradiation' was developed in which stable generic populations of mice, hare/rabbit, wolf/wild dog and deer were modelled as subjected to chronic low-LET radiation with dose rates of 0-5 × 10 -2 Gy day -1 in increments of 10 -2 Gy day -1. The duration of exposure simulations was 5 years. Results are given for the size of each surviving population for each of the applied dose rates at the end of the 1st to 5th years of exposure. Despite the theoretical differences in the modelling approaches, the inter-comparison allowed the identification of a series of common findings. At dose rates of about 10 -2 Gy day -1 for 5 years, the survival of populations of short-lived species was better than that of long-lived species: significant reduction in large mammals was predicted whilst small mammals survive at 80-100 % of the control. Dose rates in excess of 2 × 10 -2 Gy day -1 for 5 years produced considerable reduction in all populations. From this study, a potential relationship between higher reproduction rates and lower radiation effects at population level can be hypothesized. The work signals the direction for future investigations to validate and improve the predictive ability of different population dose effects models. © 2012 Springer-Verlag.

Sazykina T.G.,Research and Production Association Typhoon | Kryshev A.I.,Research and Production Association Typhoon
Journal of Environmental Radioactivity | Year: 2016

A dynamic mathematical model is formulated, predicting the development of radiation effects in a generic animal population, inhabiting an elemental ecosystem 'population-limiting resource'. Differential equations of the model describe the dynamic responses to radiation damage of the following population characteristics: gross biomass; intrinsic fractions of healthy and reversibly damaged tissues in biomass; intrinsic concentrations of the self-repairing pool and the growth factor; and amount of the limiting resource available in the environment. Analytical formulae are found for the steady states of model variables as non-linear functions of the dose rate of chronic radiation exposure. Analytical solutions make it possible to predict the expected severity of radiation effects in a model ecosystem, including such endpoints as morbidity, mortality, life shortening, biosynthesis, and population biomass. Model parameters are selected from species data on lifespan, physiological growth and mortality rates, and individual radiosensitivity. Thresholds for population extinction can be analytically calculated for different animal species, examples are provided for generic mice and wolf populations. The ecosystem model demonstrates a compensatory effect of the environment on the development of radiation effects in wildlife. The model can be employed to construct a preliminary scale 'radiation exposure-population effects' for different animal species; species can be identified, which are vulnerable at a population level to chronic radiation exposure. © 2015.

Sazykina T.G.,Research and Production Association Typhoon | Kryshev A.I.,Research and Production Association Typhoon
Radiation and Environmental Biophysics | Year: 2011

The peculiarities of radiation response in animals at low environmental temperatures are analyzed in the context of radiation safety of the Arctic/Northern wildlife. The paper includes a data review on radiation effects in cold environments based on international and Russian publications since 1948, which forms a supplement to the EPIC and FREDERICA data collections. In homoiothermic and heterothermic animals, imbalances in thermoregulation caused by ionizing radiation are discussed, which increase energy loss of animals, and decrease their fitness to the Arctic/Northern climate. In poikilothermic animals, both radiation damage and recovery are temperature dependant, their rates being slow in the cold environment. At low temperatures, radiation damage of biological tissues is conserved in hidden form; when the temperature of poikilothermic animal rises to a normal level, radiation injury is developed rapidly similar to acute dose response. Additionally, a mathematical model is described, demonstrating the combined effects of chronic radiation exposures and seasonal temperature variations on a fish population. Computer simulations show that at the same level of irradiation, the overall radiation damage to Arctic/Northern poikilothermic fish is higher than that to the fish from warm climate. Considering the peculiarities of radiation effects in the cold climate, the Arctic/Northern fauna might be expected to be more vulnerable to chronic radiation stress compared to temperate fauna. In the case of acute radiation exposure during winter periods, hibernation of heterothermic and cooling of poikilothermic animals may provide temporary protection from acute radiation effects. © 2010 Springer-Verlag.

Ingel L.Kh.,Research and Production Association Typhoon | Macosco A.A.,Russian Academy of Sciences
Doklady Earth Sciences | Year: 2014

For the first time, we analytically calculated the linear disturbances induced by inhomogeneities of the gravity force field in a stratified rotating medium. The interaction of a geostrophic current with gravity force anomalies in the model considered here can lead to notable generation of eddy disturbances. We analyzed the physical mechanism of the generation of these disturbances. © Pleiades Publishing, Ltd., 2014.

Ingel' L.K.,Research and Production Association Typhoon
Technical Physics | Year: 2013

Attention is given to an as yet unexplored mechanism of convective instability in two-component media, such as sea water. In general, different substances (for example, heat and salt) are transfered by flows in such media with different velocities depending on their diffusion rate. Therefore, situations with partial segregation of these substances giving rise to convective instability may arise. © 2013 Pleiades Publishing, Ltd.

Sazykina T.G.,Research and Production Association Typhoon | Kryshev A.I.,Research and Production Association Typhoon
Journal of Environmental Radioactivity | Year: 2016

Lower threshold dose rates and confidence limits are quantified for lifetime radiation effects in mammalian animals from internally deposited alpha-emitting radionuclides. Extensive datasets on effects from internal alpha-emitters are compiled from the International Radiobiological Archives. In total, the compiled database includes 257 records, which are analyzed by means of non-parametric order statistics. The generic lower threshold for alpha-emitters in mammalian animals (combined datasets) is 6.6·10−5 Gy day−1. Thresholds for individual alpha-emitting elements differ considerably: plutonium and americium - 2.0·10−5 Gy day−1; radium – 2.1·10−4 Gy day−1. Threshold for chronic low-LET radiation is previously estimated at 1·10−3 Gy day−1. For low exposures, the following values of alpha radiation weighting factor wR for internally deposited alpha-emitters in mammals are quantified: wR(α) = 15 as a generic value for the whole group of alpha-emitters; wR(Pu) = 50 for plutonium; wR(Am) = 50 for americium; wR(Ra) = 5 for radium. These values are proposed to serve as radiation weighting factors in calculations of equivalent doses to non-human biota. The lower threshold dose rate for long-lived mammals (dogs) is significantly lower than comparing with the threshold for short-lived mammals (mice): 2.7·10−5 Gy day−1, and 2.0·10−4 Gy day−1, respectively. The difference in thresholds is exactly reflecting the relationship between the natural longevity of these two species. Graded scale of severity in lifetime radiation effects in mammals is developed, based on compiled datasets. Being placed on the severity scale, the effects of internal alpha-emitters are situated in the zones of considerably lower dose rates than effects of the same severity caused by low-LET radiation. RBE values, calculated for effects of equal severity, are found to depend on the intensity of chronic exposure: different RBE values are characteristic for low, moderate, and high lifetime exposures (30, 70, and 13, respectively). The results of the study provide a basis for selecting correct values of radiation weighting factors in dose assessment to non-human biota. © 2016 Elsevier Ltd

Sazykina T.G.,Research and Production Association Typhoon | Kryshev A.I.,Research and Production Association Typhoon
Radiation and Environmental Biophysics | Year: 2012

A generic population model is formulated for radiation risk assessment of natural biota. The model demonstrates that effects of radiation on the population survival do not follow directly the effects on individual organisms. Dose rates resulting in population extinction can be analytically calculated. Besides individual radiosensitivity, two key parameters were found to determine the survival potential of a population under chronic radiation stress: the ratio "biomass losses/biomass synthesis", and the lump amount of limiting resource in the environment. A benchmark scenario "Population response to chronic irradiation" developed within the IAEA Programme EMRAS II was calculated for generic populations of mice, hare/rabbit, wolf/wild dog, and deer/goat chronically exposed to different levels of ionizing radiation. In the conditions of the benchmark scenario, model populations survived normally (>90% of the control value) at dose rates below the following levels: 3 mGy day -1 for wolf/wild dog; 10 mGy day -1 for deer/goat; 14 mGy day -1 for hare/rabbit; and 20 mGy day -1 for mice. The model predictions showed a relatively high survival potential of short-lived and productive species such as mice. At the same time, populations of long-lived animals with slow and radiosensitive reproduction such as wolf/wild dog were candidates to extinction at chronic exposures above 5 mGy day -1. Recovery of short-lived and productive species took a much shorter time compared with long-lived and slow reproductive species. © Springer-Verlag 2012.

Kryshev A.I.,Research and Production Association Typhoon | Sazykina T.G.,Research and Production Association Typhoon
Radiation and Environmental Biophysics | Year: 2015

The objective of the present paper was application of a model, which was originally developed to simulate chronic ionizing radiation effects in a generic isolated population, to the case of acute exposure, and comparison of the dynamic features of radiation effects on the population survival in cases of acute and chronic exposure. Two modes of exposure were considered: acute exposure (2–35 Gy) and chronic lifetime exposure with the same integrated dose. Calculations were made for a generic mice population; however, the model can be applied for other animals with proper selection of parameter values. In case of acute exposure, in the range 2–11 Gy, the population response was in two phases. During a first phase, there was a depletion in population survival; the second phase was a recovery period due to reparation of damage and biosynthesis of new biomass. Model predictions indicate that a generic mice population, living in ideal conditions, has the potential for recovery (within a mouse lifetime period) from acute exposure with dose up to 10–11 Gy, i.e., the population may recover from doses above an LD50 (6.2 Gy). Following acute doses above 14 Gy, however, the mice population went to extinction without recovery. In contrast, under chronic lifetime exposures (500 days), radiation had little effect on population survival up to integrated doses of 14–15 Gy, so the survival of a population subjected to chronic exposure was much better compared with that after an acute exposure with the same dose. Due to the effect of “wasted radiation”, the integrated dose of chronic exposure could be about two times higher than acute dose, producing the same effect on survival. It is concluded that the developed generic population model including the repair of radiation damage can be applied both to acute and chronic modes of exposure; results of calculations for generic mice population are in qualitative agreement with published data on radiation effects in mice. © 2014, Springer-Verlag Berlin Heidelberg.

Ingel L.K.,Research and Production Association Typhoon | Makosko A.A.,Russian Academy of Sciences
Izvestiya - Atmospheric and Ocean Physics | Year: 2015

Linear disturbances induced by gravity-field inhomogeneities in a horizontal stratified flow with a vertical shear are calculated analytically. In addition to being dependent on the amplitude of these inhomogeneities, disturbances depend strongly on their horizontal scales, background flow velocity, stratification, and Coriolis parameter. The most important governing dimensionless parameters are the Froude number (the ratio of inertial forces and buoyancy) and the Burger number (the ratio of the effect of rotation to the effect of stratification). The analytical solutions derived show that the influence of inhomogeneities of the gravitational field on atmospheric flows can be significant in some cases. Physical generation mechanisms of these disturbances are analyzed. © 2015, Pleiades Publishing, Ltd.

Loading Research and Production Association Typhoon collaborators
Loading Research and Production Association Typhoon collaborators