Characteristics of thunderstorm centers during the development of mesoscale convective systems over the south of Western Siberia

In this work, estimates of thunderstorm activity during the passage of mesoscale convective complexes (MCC) in the south of Western Siberia for 2016–2019 were obtained. When analyzing the trajectories of the MCC movement, it was revealed that it passes from the southwest to the northeast. The duration of the thunderstorm activity generated by the MCC is on average about 9 hours. At the same time, the duration of thunderstorm activity less than 4 hours was not noted. average area of a thunderstorm center ~ 5700 km2. The average distance covered by a thunderstorm is ~ 470 km. According to WWLLN, the number of lightning strikes is ~ 530

Gas dynamics of stationary supersonic gas jets with inert particles exhausting into a medium with low pressure

Issues related to the development of tools for mathematical modeling of stationary supersonic flows of an ideal compressible gas with inert particles are considered. A mathematical model is constructed that describes the flow of an inviscid compressible gas with inert particles in a jet flowing from an axisymmetric nozzle into a flooded space. Provided that the flow is supersonic along one of the spatial coordinates, the Euler equations are hyperbolic along this coordinate. For numerical calculations of the gas flow field, the finite volume method and the marching method are used. For integration over the marching direction, the three-step Runge–Kutta scheme is used. The procedure for calculating the flows includes the reconstruction of the values of the desired functions on the faces of the control volumes from the average values over the control volumes and the solution of the problem of the decay of an arbitrary discontinuity (the Riemann problem). The Lagrangian method of test particles is used to describe the dispersed phase. The effects of the reverse influence of particles on the flow of the carrier gas are not taken into account. The effects of viscosity and rarefaction of the gas flow are taken into account only when the gas interacts with particles. Calculation of the trajectories of inert particles is carried out in a known flow field of the carrier gas. The motion trajectories of discrete inclusions in jet flows with strong underexpansion are presented. The influence of the particle size and the coordinates of the particle entry point into the flow on the features of their transfer by the jet stream are discussed. Efficient means of numerical simulation of stationary supersonic flows of an ideal compressible gas with particles in nozzles and jets have been developed. The calculation results are of interest for studying supersonic gas suspension flows around bodies and for calculating oblique shock waves

Analysis of spatio-temporal variability of lightning activity and wildfires in Western Siberia during 2016-2021

This research compares the spatial and temporal variability of lightning activity associated with wildfires in several natural geographical zones ofWestern Siberia from 2016–2021. The study was based on the World Wide Lightning Location Network (WWLLN) and The Fire Information for Resource Management System (FIRMS) for the warm (April–October) season. It was revealed that areas of hotspots and lightning activity most often coincide in the southwestern part of the territory (near Khanty-Mansiysk and Tyumen), in the mountain regions (Kuznetsk Alatau, Altai), and in the northern part of Kazakhstan. Maximum values of lightning occur in July for the whole territory of Western Siberia, and maximum values of hotspots occur in April in the central and southern regions of Western Siberia. Despite the largest number of fires in the south of the territory, the probability of ignition from lightning over the whole warm season is higher in the northern parts ofWestern Siberia; it reaches up to 30%. Thus, the revealed lightning–fire association allows us to better understand this process in the region that will be useful in the prediction of the potential fire danger in different natural zones

Group analysis and renormgroup symmetries

An original regular approach to constructing special type symmetries for boundary value problems, namely renormgroup symmetries, is presented. Different methods of calculating these symmetries, based on modern group analysis are described. Application of the approach to boundary value problems is demonstrated with the help of a simple mathematical model.Comment: 17 pages, RevTeX LATeX file, to appear in Journal of Mathematical Physic

Kisspeptin-mediated regulation of testicular activity of rats under the effect of gold nanoparticles

З’ясовано особливості впливу наночастинок золота на функціональну активність сім’яників щурів різного віку. За інтраперитонеального уведення наночастинок золота в дозі 0,1 мг/100 г маси тіла гістологічна структура сім’яника залишається в межах норми. Встановлено пригнічувальний вплив нанозолота на ендокринну та сперматогенну активність сім’яників дорослих тварин, хоча змін морфометричних параметрів у молодих тварин не виявлено. За дії нанорозмірного золота активація кіспептинергічної системи гіпоталамуса шляхом інтрацеребровентрикулярного уведення кіспептину в бічний шлуночок мозку не викликає підвищення функціональної активності сім’яників тварин обох вікових груп. Блокування кіспептин-опосередкованої регуляції посилює пригнічувальний вплив нанозолота, при цьому в сім’яниках з’являються морфологічні ознаки пригнічення сперматогенезу. Вплив нанорозмірного золота на регуляцію активності сім’яників не залежить від віку тварини. Наші дані свідчать, що наночастинки золота порушують систему регуляторних взаємодій репродуктивної системи самців щурів, що необхідно брати до уваги у подальшому практичному застосуванні цих наноматеріалів. З’ясовано особливості впливу наночастинок золота на функціональну активність сім’яників щурів різного віку. За інтраперитонеального уведення наночастинок золота в дозі 0,1 мг/100 г маси тіла гістологічна структура сім’яника залишається в межах норми. Встановлено пригнічувальний вплив нанозолота на ендокринну та сперматогенну активність сім’яників дорослих тварин, хоча змін морфометричних параметрів у молодих тварин не виявлено. За дії нанорозмірного золота активація кіспептинергічної системи гіпоталамуса шляхом інтрацеребровентрикулярного уведення кіспептину в бічний шлуночок мозку не викликає підвищення функціональної активності сім’яників тварин обох вікових груп. Блокування кіспептин-опосередкованої регуляції посилює пригнічувальний вплив нанозолота, при цьому в сім’яниках з’являються морфологічні ознаки пригнічення сперматогенезу. Вплив нанорозмірного золота на регуляцію активності сім’яників не залежить від віку тварини. Наші дані свідчать, що наночастинки золота порушують систему регуляторних взаємодій репродуктивної системи самців щурів, що необхідно брати до уваги у подальшому практичному застосуванні цих наноматеріалів. There are a variety of biomedical applications of nanoparticles. They can be used as drug carriers, anti-tumor agents, biosensors and modulators of immune response. But full-scale real clinical application of nanomaterials requires a great deal of information on their safety and biotoxicity. Even traditionally harmless materials, like gold, can obtain toxic features when scaled to the nanosize. In vitro studies showed that nanoparticles can be geno- and cytotoxic, but their effects on the body as a whole remain largely a mystery. To shed some light on this, our study focused on the reproductive toxicity of nanomaterials. We synthesized 10–15 nm gold nanoparticles through the reduction of sodium tetrachloroaurate (III) in an alkaline medium with the addition of sodium polyphosphate as a stabilizing agent. Next, these particles were administered intraperitoneally to young and old rats for 10 days. To test functional capabilities of the testes, we injected kisspeptin-10 or its antagonist peptide-234 intracerebroventricularly. These substances are known to stimulate or inhibit the central component of the hypothalamic-pituitary-gonadal axis respectively. After the routine histological procedures, we measured the diameter of seminiferous tubules and the nuclear cross-sectional area of Sertoli cells as markers of testicular spermatogenic activity and a cross-sectional area of the Leydig cells’ nuclei as a marker of testicular steroidogenesis. We found that injections of nanogold caused no significant changes in the young animals. At the same time, morphometric parameters of adult animals were significantly lower compared to control, although we observed no pathological changes in the tissue. Combined administration of gold nanoparticles and kisspeptin showed that the stimulatory effect of the latter was not observed at all. This is a specific feature of toxicants called “endocrine disruptors”. Moreover, we found morphological signs of testicular degeneration, which are characteristic of the low-testosterone state. Simultaneous injections of gold and peptide-234 resulted in the highest degree of testicular functional downregulation, regardless of age. Taken as a whole, our data indicates that gold nanoparticles disrupt the regulatory network of the hypothalamic-pituitary-gonadal axis, possibly due to direct action on the interstitial cells and spermatogenic epithelium.

Kisspeptin-mediated regulation of testicular activity of rats under the effect of gold nanoparticles

There are a variety of biomedical applications of nanoparticles. They can be used as drug carriers, anti-tumor agents, biosensors and modulators of immune response. But full-scale real clinical application of nanomaterials requires a great deal of information on their safety and biotoxicity. Even traditionally harmless materials, like gold, can obtain toxic features when scaled to the nanosize. In vitro studies showed that nanoparticles can be geno- and cytotoxic, but their effects on the body as a whole remain largely a mystery. To shed some light on this, our study focused on the reproductive toxicity of nanomaterials. We synthesized 10–15 nm gold nanoparticles through the reduction of sodium tetrachloroaurate (III) in an alkaline medium with the addition of sodium polyphosphate as a stabilizing agent. Next, these particles were administered intraperitoneally to young and old rats for 10 days. To test functional capabilities of the testes, we injected kisspeptin-10 or its antagonist peptide-234 intracerebroventricularly. These substances are known to stimulate or inhibit the central component of the hypothalamic-pituitary-gonadal axis respectively. After the routine histological procedures, we measured the diameter of seminiferous tubules and the nuclear cross-sectional area of Sertoli cells as markers of testicular spermatogenic activity and a cross-sectional area of the Leydig cells’ nuclei as a marker of testicular steroidogenesis. We found that injections of nanogold caused no significant changes in the young animals. At the same time, morphometric parameters of adult animals were significantly lower compared to control, although we observed no pathological changes in the tissue. Combined administration of gold nanoparticles and kisspeptin showed that the stimulatory effect of the latter was not observed at all. This is a specific feature of toxicants called “endocrine disruptors”. Moreover, we found morphological signs of testicular degeneration, which are characteristic of the low-testosterone state. Simultaneous injections of gold and peptide-234 resulted in the highest degree of testicular functional downregulation, regardless of age. Taken as a whole, our data indicates that gold nanoparticles disrupt the regulatory network of the hypothalamic-pituitary-gonadal axis, possibly due to direct action on the interstitial cells and spermatogenic epithelium

Microscopic Calculation of Total Ordinary Muon Capture Rates for Medium - Weight and Heavy Nuclei

Total Ordinary Muon Capture (OMC) rates are calculated on the basis of the Quasiparticle Random Phase Approximation for several spherical nuclei from 90^Zr to 208^Pb. It is shown that total OMC rates calculated with the free value of the axial-vector coupling constant g_A agree well with the experimental data for medium-size nuclei and exceed considerably the experimental rates for heavy nuclei. The sensitivity of theoretical OMC rates to the nuclear residual interactions is discussed.Comment: 27 pages and 3 figure