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On antiperiodic boundary value problem for a semilinear differential inclusion of a fractional order q. The investigation of control systems with nonlinear units forms a complicated and very important part of contemporary mathematical control theory and harmonic analysis, which has numerous applications and attracts the attention of a number of researchers around the world. In turn, the development of the theory of differential inclusions is associated with the fact that they provide a convenient and natural tool for describing control systems of various classes, systems with discontinuous characteristics, which are studied in various branches of the optimal control theory, mathematical physics, radio physics, acoustics etc. One of the best approaches to the study of this kind of problems is provided by the methods of multivalued and nonlinear analysis, which are distinguished as very powerful, effective and useful. However, the solving of these problems within the frameworks of existing theories is often a very difficult problem, since many of them find sufficiently adequate description in terms of differential equations and inclusions with fractional derivatives. The theory of differential equations of fractional order originates from the ideas of Leibniz and Euler, but only by the end of the XX century, interest in this topic increased significantly. In the 70s - 80s, this direction was greatly developed by the works of A.A. Kilbas, S.G. Samko, O.I. Marichev, I. Podlubny, K.S. Miller, B. Ross, R. Hilfer, F. Mainardi, H. M. Srivastava. Notice that the research in this direction will open up prospects and new opportunities for the studying of non-standard systems that specialists encounter while describing the development of physical and chemical processes in porous, rarefied and fractal media. It is known that a periodic boundary value problem is one of the classical boundary value problems of differential equations and inclusions. At the same time, in recent years, along with periodic boundary value problems, antiperiodic boundary value problems are of great interest due to their applications in physics and interpolation problems. In this paper, we study an antiperiodic boundary value problem for semilinear differential inclusions with Caputo fractional derivative of order q in Banach spaces. We assume that the nonlinear part is a multivalued map obeying the conditions of the Caratheodory type, boundedness on bounded sets, and the regularity condition expressed in terms of measures of noncompactness. In the first section, we present a necessary information from fractional analysis, Mittag -- Leffler function, theory of measures of noncompactness, and multivalued condensing maps. In the second section, we construct the Green's function for the given problem, then, we introduce into consideration a resolving multivalued integral operator in the space of continuous functions. The solutions to the boundary value problem are fixed points of the resolving multioperator. Therefore, we use a generalization of Sadovskii type theorem to prove their existence. Then, we first prove that the resolving multioperator is upper semicontinuous and condensing with respect to the two-component measure of noncompactness in the space of continuous functions. In a proof of a main theorem of the paper, we show that a resolving multioperator transforms a closed ball into itself. Thus, we obtain that the resolving multioperator obeys all the conditions of the fixed point theorem and we prove the existence of solutions to the antiperiodic boundary value problem.

Globodera rostochiensis is one of the 100 most dangerous invasive species in Russia, causing significant damage to agriculture. In Russia, this nematode was first founded in Kaliningrad Region in 1949. In this study, we used ensemble modeling (ESDM) methods to predict the potential distribution of G. rostochiensis in Russia and found that with changes in global climate and land use in the future, there would be a tendency to expand the range in two directions - from the south to the north and from the west to the east. The history of the distribution of the species on the territory of Russia, the current and potential ranges of the species from 2020 to 2100 with a step of 20 years in the implementation of various models and scenarios of climate change and land use are presented. Information on native range, features of biology, signs of host plant damage and injuriousness of G. rostochiensis , methods of pathotypes identification, invasion vectors, and control measures are shown. The predicted ranges of the species are important for the development of measures to minimize future invasion of G. rostochiensis and their negative consequences

Models of ecological niches of stellate sturgeon ( Acipenser stellatus Pallas, 1771) in the northern part of the Caspian Sea based on long-term monitoring data (1992-2006) are presented. The analysis of the results of the study of the long-term patterns of the spatial distribution of alien species of polychaete Hediste diversicolor , mollusc Abra ovata and crustaceans are reported. Estimates of the effect of abiotic and biotic factors on the formation of ecological niches of the stellate sturgeon in the eastern and western regions of the northern part of the Caspian Sea are presented. Graphical schemes of the spatial distribution of stellate sturgeon in different years of monitoring in the plane of two main components (PCA) are given. It is shown that the salinity of water and the density of crustaceans are the leading factors for constructing models of ecological niches.

Abstract— The results of the analysis of the genetic variability of parthenogenetic Darevskia rostombekowi (Darevsky, 1957) species using four microsatellite-containing loci are presented. Based on 118 records with geographical coordinates of the presence of this species in Transcaucasia, the maps of potential range were created. The analysis of the genetic structure of populations demonstrated that despite the established multiclonality (seven clonal lines in four populations), D. rostombekowi was formed as a result of a single act of hybridization between closely related bisexual species. The predicted distribution of D. rostombekowi using the modelling of potential range revealed new suitable habitats, where the presence of the species has not been reported previously. The results of this study and the absence of multiple acts of hybridization during the formation of these clones may indicate a regression of population size of the species. Consequently, the estimation of the conservation status of this parthenogenetic species seems to be justified.

In parthenogenetic hybrid Darevskia armeniaca species, the development of early oogenesis and early meiosis were analyzed. It has been shown for the first time that the number of synаptonemal complexes (SCs) of bivalents during the stages of early pachуtena–diplotena of the meiotic prophase 1 is constantly equal to the haploid number, 19. The SC karyotype is presented. The results of comparative molecular–cytogenetic (C/CMA3/DAPI) analysis of the mitotic chromosomes (2n = 38: 34A + 2m + Zw-sex chromosomes) of parthenogenetic females and of the meiotic Zw-sex chromosomes (n = 19 bivalents) of a male D. armeniaca specimen with sex inversion have been presented. Finally, the results obtained demonstrate the absence of premeiotic endoreplication of chromosomes, standard early stages of meiosis, and the formation of the haploid number of SC-bivalents (n = 19) of homeological chromosomes in D. armeniaca.

Parthenogenetic species of Caucasian rock lizards of the genus Darevksia are important evidence for reticulate evolution and speciation by hybridization in vertebrates. Female-only lineages formed through interspecific hybridization have been discovered in many groups. Nevertheless, critical mechanisms of oogenesis and specifics of meiosis that provide long-term stability of parthenogenetic species are still unknown. Here we report cytogenetic characteristics of somatic karyotypes and meiotic prophase I nuclei in the diploid parthenogenetic species Darevskia unisexualis from the new population "Keti" in Armenia which contains an odd number of chromosomes 2n = 37, instead of the usual 2n = 38. We revealed 36 acrocentric chromosomes and a single metacentric autosomal chromosome, resulting from Robertsonian translocation. Comparative genomic hybridization revealed that chromosome fusion occurred between two chromosomes inherited from the maternal species, similar to another parthenogenetic species D. rostombekowi. To trace the chromosome behaviour in meiosis, we performed an immunocytochemical study of primary oocytes' spread nuclei and studied chromosome synapsis during meiotic prophase I in D. unisexualis based on analysis of synaptonemal complexes (SCs). We found meiotic SC-trivalent composed of one metacentric and two acrocentric chromosomes. We confirmed that the SC was assembled between homeologous chromosomes inherited from two parental species. Immunostaining of the pachytene and diplotene nuclei revealed a mismatch repair protein MLH1 loaded to all autosomal SC bivalents. Possible mechanisms of meiotic recombination between homeologous chromosomes are discussed.

In yttrium aluminum garnet (YAG) crystals containing terbium and cerium impurities, along with the main EPR signals of Tb3+ and Се3+ ions located in the dodecahedral sites of the YAG lattice in a regular environment, EPR lines with a lower (several percent) intensity were observed. They also belong to the paramagnetic centers of terbium and cerium, but are characterized by slightly altered parameters—the initial level splitting for non-Kramers Tb3+ ions and g-factors for Се3+ ions. It is shown that the nature of such centers and their number can be explained by the presence of YAl antisite defects, i.e. yttrium ions in the octahedral aluminum positions, in the environment of Tb3+ and Се3+.

The results of experiments on natural distribution of seeds of the giant hogweed (Heracleum sosnowskyi Manden.) in the winter period are presented. It was found that viable seeds are preserved on the umbrellas of this alien plant in winter. Falling of single seeds during the winter period is not much different from falling of seeds in the summer–autumn period. It was shown that seeds under the influence of various factors, in particular, under the influence of strong gusts of wind, can move up to 5 m from the mother plant. It was revealed that the seeds are also able to move together with broken umbrellas over distances many times greater than the distances of the natural scattering of single seeds. Experimental observations on the movement of umbrellas at a distance of 40 ± 9 m for 15 min suggest that the range of movement of umbrellas can be hundreds of meters on a flat surface of icy roads. The high germination of seeds left on the umbrellas allowed us to conclude that measures to control Sosnowsky’s hogweed should include the destruction of dead plants with seeds until a stable snow cover is formed.

The article explores the problems and prospects of further reforming and improving financial support for social protection of the population in Ukraine. The modern problems of financing the sphere of social protection of the population in Ukraine are identified and ways to overcome them are outlined. The analysis of expenses of the consolidated budget of Ukraine for education in 2010-2018 is carried out. It has been revealed that the most significant source of financing for healthcare institutions is the funds of state and local budgets, while funds received from other sources are only an additional financial resource. Therefore, the main form of financial support for the health sector is budget financing. It is determined that the source of financing social security is the budget and extrabudgetary sources. The types of sources of financing social security are given. It is proved that one of the significant obstacles to the effective implementation of social policy in our country is the insufficient level of its financial support, combined with the irrational planning, distribution and inefficient use of available financial resources. The dynamics of the size of the main state social standards of Ukraine in 2014-2019 is presented. An analysis of the data showed that the size of the minimum pension in Ukraine is several times less than the value of the minimum consumer basket, which is the basis for determining the level of the living wage and, in fact, the level of the living wage. Such an imbalance indicates an extremely low level of social protection of the country's population. A set of measures is proposed to solve the problems of financing the sphere of social protection of the population in Ukraine. The main directions of ensuring high-quality social protection of the population of Ukraine are determined.

We consider the problem for a functional differential inclusion of fractional order with a general initial condition expressed in the form of an operator inclusion in a Banach space. At the beginning of the paper, an introduction is presented in which the relevance of the study is substantiated, then preliminary information from fractional analysis, the theory of measures of noncompactness and condensing mappings, as well as some information from multivalued analysis are given. In the second subsection, we state the problem and its solution on the basis of the theory of condensing multivalued mappings. In the last subsection, we give an example of a particular case of the solved problem, in the case of an antiperiodic boundary condition.

In crystals of yttrium orthoaluminate doped with the 151Eu isotope, Eu2+, Cr3+, Gd3+, and Мо3+ paramagnetic centers are detected. The fine structure parameters of the spin Hamiltonian are determined or refined for these centers. The orientation behavior of previously unobserved forbidden transitions is considered for the Cr3+ centers. It is shown that two Mo3+ signals that are detected in magnetic fields directed parallel to the crystallographic axes do not belong to different molybdenum centers, but are two intradoublet transitions of the same center.

The article presents the analysis of the influence of anthropogenic conditions on the dynamics of life forms of meadow plants using the indices of the average number and stability of life forms based on data from long-term monitoring of Zalidov meadows of Kaluga region. It is shown that regular mowing leads to an increase in rod-root plants and an abundance of economically insignificant species. With regular moderate grazing, the number of long root-growing life forms increases, and the abundance of high-value plant species increases. It has been established that for rational use of Zalidov meadows, haying and pasture regimes should be alternated. The issues of the applicability of the indices used to identify general trends in the development of the meadow community depending on anthropogenic impact are discussed.

Protection of the containment integrity is one of the key objectives pursued in managing a severe accident at an NPP. Possible hydrogen inflammation in the containment can be regarded as the most dangerous threat for the containment integrity. Inert state of a steam–air–hydrogen mixture can be secured by maintaining a high steam concentration. With a steam concentration above 55%, the mixture is in an non-flammable state whatever the concentrations of its other components. The containment reinforced concrete walls lined with metal sheets behave as heat sinks with a very high thermal inertia. Heat removal through walls may have a significant influence on the mixture composition in the containment or in its individual part (especially if the rooms have comparatively small volumes) if part of steam from the mixture undergoes long-term condensation, as a result of which its concentration in the mixture decreases. The article presents an investigation, by means of detailed modeling, of the heat transfer processes through the walls of containment rooms with a view to reveal factors that are of importance in considering hydrogen challenge. It is found that the wall surface area to the room volume ratio is a factor having an effect on the formation of dangerous hydrogen-containing mixture compositions. It is shown that the wall heat absorption capacity decreases only slightly in the course of an accident. In rooms with a small volume, there may be a real risk that the medium in them may quite quickly lose its inertness as a result of heat removal through the walls. The possibility of a detonation mixture to form is not even excluded. In the case of a severe accident, there will be a risk of dangerous hydrogen-containing mixture compositions formation in small rooms within the containment irrespectively of the strategies implemented for the containment’s main rooms unless special measures and means are taken, e.g., application of accident management strategies or installation of hydrogen recombiners.

Based on the analysis of the forward current-voltage characteristics of the p-InSb–n-CdTe heterojunction fabricated by a method of pulsed laser deposition, the existence of two charge injection mechanisms was experimentally confirmed. At relatively small external bias voltages (0.03 V < U < 0.15 V), the current is in a satisfactory agreement with the expression I ~ exp(qU/ηkT) with the ideality factor η = 1. Above 0.18 V, the current-voltage characteristic obeys the law I ~ U3/2 followed by an attainment to the linear section (the cut-off voltage of current is 0.47 V). A theoretical model of current transport is given taking into account the peculiarities of the heterojunction band discontinuity, leading to the origination of inversion layer near the interface.

Open access to occurrence records of the most dangerous invasive species in a standardised format have important potential applications for ecological research and management, including the assessment of invasion risks, formulation of preventative and management plans in the context of global climate and land use changes in the short and long perspective. The striped field mouse (Apodemus agrarius Pallas, 1771) is a common species in the temperate latitudes of the Palaearctic. Due to land use and global climate changes, several waves of expansion of the range of this species have been observed or inferred. By intrusion into new regions, the striped field mouse has become an alien species there. Apodemus agrarius causes significant harm to agriculture and is one of the most important pests of grain crops. In tree nurseries, A. agrarius destroys seeds of valuable tree species and gnaws at the bark of saplings of broadleaf species and berry bushes. It is one of the most epidemiologically important rodents, involved in the circulation of the causative agents of haemorrhagic fever with renal syndrome (HFRS) and many other zoonotic infections. The foregoing allows us to classify the striped field mouse as a dangerous invasive alien species in the expanding part of the range. A lot of data accumulated for this species are of interest from both ecological and applied points of view. The accumulation and aggregation of data on the occurrence records of A. agrarius is relevant for the study of ecology, biogeography and construction of the spatial distribution and ecological niche models in the context of global climate change. We have created a dataset of 1603 occurrence records of this species, collected from 1936 to December 2020 by various zoologists, previously published or original. These records relate to a significant part of the striped field mouse’s range in Russia (1264 records) and neighbouring countries (339 records). The dataset shows the position of the northern and central parts of A. agrarius range, the disjunction of the range in Transbaikalia and isolated populations in the north of the range. The data were obtained in different formats from literature, indicating different degrees of accuracy of geographic coordinates and with several variations of the species' name. In the process of aggregating and fixing errors, we created a set of georeferenced occurrence records, adopted a controlled vocabulary, removed duplicates and standardised the format of records using unified data structure. We examined the dataset for inconsistencies with the taxonomic position of A. agrarius and removed the incorrect records. This paper presents the resulting dataset of A. agrarius occurrence records in the territory of Russia and neighbouring countries in a standardised format. This is a validated and comprehensive dataset of occurrence records of A. agrarius, including both our own observations and records from literature. This dataset is available for extension by other researchers using a standard format in accordance with Darwin Core standards. In different countries, there are a lot of occurrence records for the striped field mouse, but the overwhelming part of them is presented in separate literary sources, stored in the form of maps and in zoological collections. Prior to this project, such information was not available to a wide range of researchers and did not allow the use of these spatial data for further processing by modern methods of analysis, based on geographic information systems (GIS technologies). The created dataset combines species occurrence records of many Soviet zoologists who studied the distribution of the striped field mouse over a significant part of its recent range, in Russia and neighbouring countries (within the former USSR). The final set of records was created by combining the species occurrence records using a uniform data structure, checking geographic coordinates and removing duplicate and erroneous records. The dataset expands the available information on the spatial and temporal distribution of the dangerous invasive species in Russia and neighbouring countries of the former USSR (Estonia, Latvia, Lithuania, Belarus, Ukraine, Moldova, Georgia, Azerbaijan, Kazakhstan and Kyrgyzstan).

Background Caucasian rock lizards of the genus Darevskia are unique taxa, including both bisexual and parthenogenetic species. The parthenogenetic species have originated as a result of natural hybridisation between females and males of different bisexual species. The species involved in interspecific hybridisation are called parental. However, sympatric zones (SZ) of unisexual and bisexual rock lizards of the Caucasus are still poorly studied, although they are very important for understanding the role of hybrid individuals of different origin in reticulate evolution. This paper presents the location of the SZs of parthenogenetic and their parental bisexual rock lizards of the genus Darevskia in Armenia and adjacent territories of Georgia and Nagorno-Karabakh. We summarised the locations of the SZs identified from 1957 to the present, based on our field survey data gathered in 2018-2019 and records from publications and museum collections. This dataset includes 39 SZs of three types: SZ of parental bisexual species, SZ of parental species with unisexual species and SZ of the parthenogenetic species. For each zone, species composition, geographical and altitudinal distribution are presented. New records expand our knowledge of the geographical and altitudinal distribution of SZs in these species and provide additional data for understanding the mechanisms of reticulate evolution and hybridogeneous speciation in the past, present and future. New information The new records, including geographical and altitudinal distributions of three types of SZs, are presented, which expand the previously-known list to 39 locations of contact zones for parthenogenetic and its bisexual parental species of rock lizards of the genus Darevskia in Armenia and the adjacent territories of Georgia and Nagorno-Karabakh.

Problems in tax administration, especially direct taxation, are one of the most important challenges for the taxation system of Armenia. The high level of the informal sector further affects the effective functioning of the system and the replenishment of the state budget. In this regard, there is a need for reforms in direct taxation presented in this article. The research objective is to evaluate possible effects of abolishment of proft tax in the Armenian economy. For this purpose, we approached the neoclassical dynamic general equilibrium model presented in expanded form and in discrete time. Impact assessment of the reforms in corporate taxation system in Estonia and Georgia was also based on the same model. Therefore, after the effects of the abolishment of proft tax in the Armenian economy are assessed, a comparative analysis of the results observed with those of Estonia and Georgia will be conducted. The model calculates the effect of changes in income tax rates on government revenues, capital per unit of labor, level of consumption and output in the country. The article also presents the parameterization of the model considering the specifcs of the Armenian economy. The study has revealed that reforming the taxation system for organizations in Armenia will lead to an increase in the general welfare of the population, net investments and aggregate output. At the same time the tax revenues of the state budget of Armenia will decrease by 3.92%. The results of the study will allow the government of Armenia to apply a new approach to taxing the profts of organizations. It will lead to an increase in the transparency of business, a decrease in the level of corruption and the concealment of the profts.

Electron paramagnetic resonance of rhombic Eu2+ centers in single crystals of Lu3Al5O12 doped with europium ions with the natural isotope abundance was studied. Parameters of the hyperfine and quadrupole interactions of 151Eu and 153Eu isotopes of these centers were determined.

The results of recent studies on invasions of alien species in the Holarctic are given in a review format. Most of these studies were presented at the Fifth International Symposium “Invasions of Alien Species in the Holarctic,” which was held in Russia in 2017. For this review, we used recent publications in the Russian Journal of Biological Invasions and other journals. The main trends in studies of invasions of alien species in the Holarctic are highlighted.

The crystals of yttrium–aluminum garnet with an admixture of iron and cerium have been studied by the method of wideband EPR spectroscopy. Resonance absorption of microwave radiation in the frequency range 220–300 GHz was detected. Based on the experimental data set, it is concluded that the signals belong to the Mo3+ ion, which is included in the crystals as an uncontrolled impurity. A straightforward method was used to measure the splitting in a zero field between the Kramers doublets |±1/2〉 and |±3/2〉 (261.6 ± 0.5 GHz). The calculated angular and frequency-field dependences of the EPR spectra are in good agreement with the experiment.

The bivalve Dreissena polymorpha (Pallas, 1771) was shown to significantly decrease the biomass of cyanoprokaryotes in water collected from Lake Mikolajskoe (Poland) including potentially toxic species Cylindrospermopsis raciborskii (Woloszynska) Seenayya et Subba Raju. However, the mollusks increased the biomass of large filaments of green algae which are of low nutritional quality for zooplankton.

The experimental results of studying the temperature dependence of the optical transmission spectra of silicate glasses containing CdSxSe1–x semiconductor nanocrystals are presented. The dependence of the band-gap energy temperature coefficient on the average nanocrystallite size is found. The possibility of the practical application of silicate glasses containing semiconductor nanocrystals as optical thermometers and optical filters is shown.

The purpose of this study was to determine how zebra mussels affected cladoceran community structure under eutrophic conditions. We conducted a mesocosm study where we manipulated the presence of zebra mussels and the presence of large-bodied Daphnia (Daphnia magna and Daphnia pulicaria). We also conducted a complimentary life-table experiment to determine how water from the zebra mussel treatment affected the life history characteristics of the cladoceran species. We anticipated that small- and large-bodied cladoceran species would respond differently to changes in algal quality and quantity under the effects of zebra mussels. Large-bodied Daphnia successfully established in the zebra mussel treatment but failed to grow in the control. We did not observe positive relationships between food concentrations and cladoceran abundances. However, the phosphorus content in the seston indicated that food quality was below the threshold level for large-bodied cladocerans at the beginning of the experiment. We believe that zebra mussels quickly enhanced the phosphorus content in the seston due to the excretion of inorganic phosphorus, thus facilitating the development of large-bodied Daphnia. In conclusion, our results suggest that zebra mussels can alter the phosphorus content of seston in lakes and this can affect the dynamics of crustacean zooplankton.

The population diversity of the frit fly Meromyza saltatrix from Poland, Mongolia, and several regions of the Russian Federation was analyzed by morphometric and molecular data on the mtDNA locus COI. Two phenotypes that correspond to two haplogroups (19 haplotypes) were identified by the absence or presence of black setae on the lower surface of the genae. A remarkable clinal variability among populations was demonstrated by the total area and area of the projecting part of the anterior processes of postgonites (APP), which play a critical role in the success of male copulation. Each parameter analyzed divided populations into four groups. Close populations with a natural barrier vary in the total area of the anterior process of the postgonite. We found an increased number of mutations including transversions in frit flies from Mongolia. Populations from Zvenigorod, South Ural Nature Reserve, and Mongolia might be of a later origin. The presence of particular haplogroup in the West European population of M. saltatrix with black setae, which is a unique feature of West European species of Meromyza, and their similarity to the Crimean population by the morphometrics of the APP is an indication of the possible isolation of this population in southern Europe during Quaternary glaciations with subsequent expansion to the northern part of the geographical area.

The results of analysis of the frequencies of t-alleles and heterozygous +/t individuals of house mice of different subspecies (musculus, bactrianus, tataricus, wagneri, and gansuensis) are presented for the natural populations inhabiting eight cities and five regions of Russia and adjacent countries of Eastern Europe and Asia. It is shown that the frequencies of t-alleles are 0.18 ± 0.03 in small samples (1–30 individuals) and 0.09 ± 0.06 in medium-sized samples (31–60 individuals). The factors that reduce the frequencies of t-alleles in natural populations and the mechanisms that prevent invasion and fixation of t-mutant alleles in the Mus musculus genome are discussed.

Phosphorus and nitrogen concentrations in the trophogenic zone in lakes are main factors determining the trophic state of lakes. The goal of this work was to assess the impacts of enrichment of lake water with nutrients, as well as the presence of large crustaceans, Dreissena polymorpha and fish on the process of phosphorus regeneration by zooplankton (rotifers and crustaceans) in experimental mesocosms. The experiment was carried out for 32 days and consisted of 12 treatments, each replicated in triplicate. The mesocosms were filled with 270 L of natural pelagic water from the eutrophic Lake Mikolajskie and kept on the shore of the lake. Fish did not to have any impact on phosphorus regeneration rates in any of the treatments, whereas the presence of bivalves increased phosphorus regeneration rates. Phosphorus regeneration rates did not affect phosphorus sedimentation in any of the treatments, but the loss of total phosphorus and its increased regeneration rates resulted in markedly decreasing turnover times of phosphorus in all treatments of the experiment. Nutrient enrichment mainly affected phosphorus regeneration by phytophagous and predatory crustaceans and had no impact on phosphorus regeneration by rotifers when large Cladocera were absent. Processes of phosphorus regeneration and uptake included in internal phosphorus cycling were under strong influence of biological factors, which acted quickly, through the changing trophic structure of zooplankton communities, which in turn changed the flow of phosphorus in trophic chains.

One of the main objectives of severe accident management at a nuclear power plant is to protect the integrity of the containment, for which the most serious threat is possible ignition of the generated hydrogen. There should be a monitoring system providing information support of NPP personnel, ensuring data on the current state of a containment gaseous environment and trends in its composition changes. Monitoring systems’ requisite characteristics definition issues are considered by the example of a particular power unit. Major characteristics important for proper information support are discussed. Some features of progression of severe accident scenarios at considered power unit are described and a possible influence of the hydrogen concentration monitoring system performance on the information support reliability in a severe accident is analyzed. The analysis results show that the following technical characteristics of the combustible gas monitoring systems are important for the proper information support of NPP personnel in the event of a severe accident at a nuclear power plant: measured parameters, measuring ranges and errors, update rate, minimum detectable concentration of combustible gas, monitoring reference points, environmental qualification parameters of the system components. For NPP power units with WWER-440/270 (230) type reactors, which have a relatively small containment volume, the update period for measurement results is a critical characteristic of the containment combustible gas monitoring system, and the choice of monitoring reference points should be focused not so much on the definition of places of possible hydrogen pockets but rather on the definition of places of a possible combustible mixture formation. It may be necessary for the above-mentioned power units to include in the emergency operating procedures measures aimed at a timely heat removal reduction from the containment environment if there are signs of a severe accident phase approaching to prevent a combustible mixture formation in the containment.