bluuebunny/crossref_metadata_2025 huggingface dataset:
Black Hole and Dark Matter in the Synchronous Coordinate System
Authors: Meyerovich B. E
Published: April 2024

The static state of a black hole in interaction with dark matter is considered in the synchronous coordinate system. Just as in Schwarzschild coordinates, in synchronous coordinates there exists a regular static spherically symmetric solution of the system of Einstein and Klein–Gordon equations that describes the state of matter extremely compressed by its own gravitational field. There is also no constraint on the mass. There also exist two gravitational radii with the boundary conditions at which the solutions are not unique. In contrast to Schwarzschild coordinates, in synchronous coordinates the determinant of the metric tensor and the component g11(r) do not become zero at the gravitational radii. In synchronous coordinates, in contrast to Schwarzschild coordinates, in the spherical layer between the gravitational radii the signature of the metric tensor is not violated. In synchronous coordinates the Einstein and Klein–Gordon equations are reduced to a system of the second (rather than fourth) order. The solutions were obtained analytically, so that no numerical calculations were required. The gravitational mass defect in the λψ4 model was determined. The total mass of matter turns out to be thrice the Schwarzschild mass determined by a remote observer when compared with Newtonian gravity.
On the Theory of Nucleation of Ionic Salts from Aqueous Solution
Authors: Veshchunov M. S
Published: April 2024

The theory of nucleation of ionic salts from aqueous solution is critically analyzed and further developed in two limiting cases of sparingly and highly soluble strong electrolytes. In the case of sparingly soluble colloids with a relatively large screening length (compared to the radius of the critical nucleus), the classical nucleation theory is modified by taking into account the influence of the critical nucleus charge on the nucleation rate, which was disregarded in earlier models. In the opposite limit of highly soluble colloids which are characterized by a relatively small screening length, the influence of the critical nucleus charge on the nucleation rate can be neglected with good accuracy. However, the discrepancy with earlier models, mainly related to the value of the pre-exponential factor, can reach several orders of magnitude.
YBaCo4O7 + x (x = 0, 0.1) System: From Antiferromagnetism to Ferromagnetism
Authors: Kazey Z. A. , Markina M. M. , Snegirev V. V. , Stolyarenko M. S.
Published: April 2024

The modification of magnetic and elastic properties of YBaCo4O7 +x(x= 0, 0.1) cobaltites at a slight controlled deviation from stoichiometry (x) has been investigated. The magnetic properties of stoichiometric YBaCo4O7demonstrate nontrivial behavior, which is inconsistent with the generally accepted notion of phase transitions with long-range magnetic order. Only magnetic moment ΔM=MFC–MZFCinduced by an external magnetic field (an analog of thermoremanent magnetization) exhibits anomalies at magnetic phase transition temperaturesTN1andTN2that coincide with those of Young’s modulus anomalies, whereas in the magnetic susceptibility curves taken in the FC and ZFC modes, phase transitions are not discerned. Ata small off-stoichiometry (x= 0.1), induced moment ΔMrises by an order of magnitude and a residual ferromagnetic moment of about 10–3μBarises in the magnetization curves. Two scenarios of the cobalt subsystem magnetic behavior with increasing part of cobalt ions Co3+have been discussed. It has been found that when YBaCo4O7 +xcobaltites deviate from stoichiometry, the evolution of their magnetic properties is similar to that observed at the transition from Y-based to Ca-based cobaltite.
Optimization of Feedback-Loop Parameters in Thulium Optical Clocks at Synchronous Comparison
Authors: Tregubov D. O. , Provorchenko D. I. , Mishin D. A. , Kolachevskiy N. N. , Golovizin A. A.
Published: April 2024

Synchronous comparison of optical clocks using phase-coherent clock lasers makes it possible to determine the difference (ratio) of clock transition frequencies, which is not limited by the total noise of lasers in use. A detailed simulation of the comparison of two thulium optical clocks is performed using synchronous interrogation of atoms by the radiation of a common clock laser. Some critical parameters have been determined, specifically: the residual noncorrelated frequency and amplitude noises of test pulses and reading noises, which may deteriorate the comparison stability. At the same time, it is demonstrated that this way is insensitive to fluctuations in the number of atoms, calibration of feedback-loop parameters, individual ejections in measurement cycles, and fluctuations of laboratory magnetic field.
On the Possibility of Controlling the Second Harmonic Radiation of the Free Electron Laser Using the Second Harmonic of the Undulator Field
Authors: Zhukovskiy K. V.
Published: April 2024

The second harmonic radiation of a single-pass free electron laser (FEL) and its dependence on the second harmonic of the undulator field are investigated. In analysis of properties of materials, the nonlinear generation of the second harmonic as a response to radiation is an important effect. In this context, the second harmonic generation of the radiation source (FEL) is undesirable since it masks the signal being analyzed. Conversely, in other cases, the second harmonic radiation of the FEL can be useful as radiation with a higher frequency. We investigate the possibility of suppression (or, conversely, enhancement) of the FEL second harmonic power depending on the phase and strength of the second harmonic of the FEL undulator field. The proposed approach is independent in principle of the radiation frequency. We consider examples of LCLS and PAL-XFEL in the X-ray range and SPARC and LEUTL in the visible range. The more effective influence of the undulator field harmonic in operation with narrow electron beams is demonstrated.
On the Exact Solution for a Luttinger Liquid with Repulsion and a Single Point Impurity
Authors: Afonin V. V , Petrov V. Yu
Published: April 2024

The expression for the conductance of a 1D channel, which has been obtained using the well-known exact solution, is analyzed. It is shown that in the case of strong electron—electron interaction, the slowest (linear in frequency) asymptotics of the conductance is determined by the behavior of electron—electron interaction in the region of transition from 1D to 3D motion realized near the impurity.
Antiferromagnetic Excitonic Insulator
Authors: Val'kov V. V
Published: April 2024

The effective the two-band Hamiltonian is obtained for iridium oxides with account for strong electron correlations (SEC) and the spin–orbit interaction. The intraatomic electron correlations in iridium ions induce the formation of Hubbard fermions (HF) filling the states in the valence band. Another consequence of SEC is associated with the emergence of the antiferromagnetic (AFM) exchange interaction between HF in accordance with the Anderson mechanism. As a result, a long-range antiferromagnetic order is established in the system, and in the conditions of band overlapping, the intersite Coulomb interaction induces a phase transition to the excitonic insulator (EI) state with a long-range AFM order. The system of integral self-consistent equations, the solution to which determines the excitonic order parameter components Δi, j(k), sublattice magnetization M, Hubbard fermion concentration nd, and chemical potential μ, is obtained using the atomic representation, the method of two-time temperature Green’s functions, and the Zwanzig–Mori projection technique. The symmetry classification of AFM EI phases is performed, and it is shown that in the nearest neighbor approximation, state Δi, j(k) with the s-type symmetry corresponds to the ground state, while the phases with the d- and p-symmetries are metastable.
Structural Disorder, Specific Heat, and Magnetic Transitions in Cu2FeBO5
Authors: Gokhfel'd Yu. S , Kazak N. V , Bel'skaya N. A , Molokeev M. S , Gudim I. A , Kondrat'ev O. A , Eremin E. V , Knyazev Yu. V , Velikanov D. A
Published: April 2024

Cu2FeBO5 ludwigite single crystals have been grown from a solution–melt by spontaneous crystallization. Using the X-ray diffraction method, the crystal structure has been resolved in detail. Cations in sites M2, M3, and M4 have turned out to be structurally disordered. It has been found that oxygen atoms are disordered in one of five nonequivalent sites (O4). As can be seen from Mössbauer spectroscopy data, Fe3+ ions occupy four nonequivalent sites with different distortions of coordination octahedra. In the temperature range 40 K ≤ T ≤ 300 K, the spectra represent a superposition of quadrupole doublets. Static susceptibility measurements have revealed two magnetic features at T1 = 35 K and T2 = 20 K and spin-glass effects. Specific heat measurements in the interval 4–300 K have not discovered magnetic-transition-related anomalies.
Effect of Heating on the Generation and Properties of Platicons in High-Q Optical Microresonators
Authors: Lobanov V. E.
Published: April 2024

Pumping a high-Q optical microresonator by an external laser is inevitably associated with thermal effects. They have a significant impact on the dynamics of nonlinear processes in such structures, including the generation of optical frequency combs and dissipative solitons. The generation process and the properties of bright solitons in such heated microresonators with anomalous group velocity dispersion (GVD) have been well studied, and a number of methods have been developed to minimize the effect of thermal processes. However, for dark solitons or platicons excited at normal GVD, these issues have been studied significantly less. In this work, the properties of platicons in heated microresonators are analyzed, and it is shown that in the case of “positive” thermal effects, when the direction of the thermal shift of the resonance frequencies of a microresonator coincides with the direction of the nonlinear shift, the widest high-energy platicons with the duration close to the round trip time in the resonator are stable. In the case of “negative” thermal effects, narrow low-energy platicons remain stable. Moreover, in microresonators with “negative” thermal effects, the interaction between cubic nonlinear and thermal processes can ensure the generation of platicons without special techniques required in other cases.
Zeeman Splitting of Excitons in GaAs/AlGaAs Quantum Wells in the Faraday Geometry
Authors: Grigor'ev F. S. , Chukeev M. A. , Lovtsyus V. A. , Efimov Yu. P. , Eliseev S. A.
Published: April 2024

The Zeeman splitting in the GaAs/AlGaAs heterostructure is investigated experimentally. Numerical analysis performed for the wavefunctions of exciton states, which takes into account the bands of heavy holes, light holes, and the band split by the spin–orbit interaction, is the quantitative agreement with experimental data both for an exciton with a heavy hole and for that with a light hole. It is shown that for explaining the experimental values of the Zeeman splitting in the quantum well under investigation, it is necessary to take into account both the Coulomb interaction and the contribution from the three bands in the valence band. The effect of screening of exciton states by a 2D gas of electrons with concentration n ≈ 109 cm–2 is described. Numerical calculations are performed for a large range of quantum well widths and aluminum concentrations in barriers; the chart of the dependence of the effective g factor on these parameters is plotted for magnetic field B = 5 T.
Measurement Sensitivity of the Optically Detected Magnetic Resonance for a Single NV– Center in Diamond
Authors: Kukin N. S. , Muradova A. R. , Nikitin A. K. , Bukhtiyarov A. A. , Semenov P. A. , Vasil'ev A. N. , Kargin N. I. , Smirnova M. O. , Terent'ev S. A.
Published: April 2024

The spectra of the optically detected magnetic resonance for single NV– centers have been experimentally studied in two solid-state samples in the range of hyperfine interactions between the electron spin and the nitrogen nucleus spin in the same NV– center. This study has been aimed at reaching a maximal microwave frequency resolution in the experimental setup used. For measurements, two low-nitrogen (no higher than 50 ppb) diamond single-crystal samples have been grown. Measured time T*2 of the spin decoherence in NV– centers was about 2 μs in one sample and 20 μs in the other. For both samples, the spectrum of the optically detected magnetic resonance for the hyperfine splitting of a single NV– center and 14N atom has been taken and investigated. The resolution in these samples has been estimated at a level of 3.5 and 0.18 MHz, respectively. It has been noted that the resolution of the spectrum improves with increasing time T*2 of the spin decoherence of the single NV– center.
Ghost Fiber Optic Endoscopy with Several Single-Pixel Detectors in the Object Arm
Authors: Balakin D. A. , Belinskiy A. V.
Published: April 2024

We describe a new method for the formation of optical ghost images, in which radiation in the object arm is detected by several detectors. The advantage of the proposed method is demonstrated, which is the smaller number of illumination patterns required for reconstructing the object image as compared to traditional schemes of ghost imaging. We propose variants of algorithms for measurement reduction to the form relevant to the imaging of the object of investigation, which are aimed at improvement of the performance of the computing component of the endoscope. The fiber-optic version of ghost imaging considered here is suitable for investigating hard-to-reach abdomens and organs of human organism, which permit the introduction of a thin fiber-optic bundle, thus extending its applicability as compared to traditional optic endoscopic methods.
Spin Pumping by a Moving Domain Wall at the Interface of an Antiferromagnetic Insulator and a Two-Dimensional Metal
Authors: Mal'shukov A. G.
Published: April 2024

A domain wall (DW) which moves parallel to a magnetically compensated interface between an antiferromagnetic insulator (AFMI) and a two-dimensional (2D) metal can pump spin polarization into the metal. It is assumed that localized spins of a collinear AFMI interact with itinerant electrons through their exchange interaction on the interface. We employed the Keldysh formalism of Green’s functions for electrons which experience potential and spin-orbit scattering on random impurities. This formalism allows a unified analysis of spin pumping, spin diffusion and spin relaxation effects on a 2D electron gas. It is shown that the pumping of a nonstaggered magnetization into the metal film takes place in the second order with respect to the interface exchange interaction. At sufficiently weak spin relaxation this pumping effect can be much stronger than the first-order effect of the Pauli magnetism which is produced by the small nonstaggered exchange field of the DW. It is shown that the pumped polarization is sensitive to the geometry of the electron’s Fermi surface and increases when the wave vector of the staggered magnetization approaches the nesting vector of the Fermi surface. In a disordered diffusive electron gas the induced spin polarization follows the motion of the domain wall. It is distributed asymmetrically around the DW over a distance which can be much larger than the DW width.
CHRONIC DYSREGULATION OF GLUTAMATERGIC TRANSMISSION IN THE HIPPOCAMPUS OF KRUSHINSKY–MOLODKINA RATS INDUCED BY REPEATED EPILEPTIFORM SEIZURES
Authors: Aleksandrova E. P. , Ivlev A. P. , Kulikov A. A. , Nikitina L. S. , Glazova M. V. , Chernigovskaya E. V.
Published: April 2024

Temporal lobe epilepsy is characterised by the development of associated neurological and psychiatric disorders. One of the possible causes is obviously a disturbance in the balance of the excitatory and inhibitory neurotransmitter systems of the hippocampus. Chronic abnormalities in the molecular mechanisms of regulation of hippocampal glutamatergic system activity in temporal lobe epilepsy are currently poorly understood. In the present study, we used Krushinsky–Molodkina (KM) rats subjected to repeated audiogenic seizures to simulate temporal lobe epilepsy. Molecular mechanisms of regulation of glutamate production by hippocampal neurons were analysed one week after the end of short-term (14 seizures) and long-term (21 seizures) kindling. In the hippocampus of КM rats, kindling results in activation of ERK1/2 kinases as well as activation of the transcription factor CREB and increased expression of the transcription factor Fra1, glutaminase and the vesicular glutamate transporters VGLUT1 and 2, that is proteins responsible for glutamate production. These data indicate increased activity of glutamatergic hippocampal neurons persisting for a week at rest after the completion of the last audiogenic stimulation. Enhanced expression of mGluR1 glutamate receptors, whose activation is known to result in Ca2+ release and increased excitotoxicity, is also shown. Long-term enhancement of glutamatergic transmission induced by repeated epileptiform seizures is not only responsible for further epileptogenesis, but may also underlie the development of neurodegenerative complications.
THE CATALYTIC PROPERTIES OF LACTATE DEHYDROGENASE IN SKELETAL MUSCLES AND LIVER OF THE MARSH FROG (PELOPHYLAX RIDIBUNDUS) DEPEND ON ITS ECOLOGICAL AND GEOGRAPHICAL LOCATION
Authors: Rabadanova Z. G. , Dzhafarova A. M.
Published: April 2024

The marsh frog (Pelophylax ridibundus) has a widespread distribution range, which is due to a variety of adaptations that contribute to the development of tolerance to a wide range of physicochemical environmental factors. Of particular interest are the adaptations of these animals to different levels of oxygen in mid- and high-altitude conditions. In this work, a comparative analysis of the kinetic parameters of lactate dehydrogenase (LDH) in the liver of marsh frogs living in the mountainous and lowland regions of Dagestan was carried out. Animals caught in their habitats were decapitated, the liver and calf muscles were isolated, and they were placed in liquid nitrogen. In the laboratory, the selected tissues were homogenized and mitochondria-free cytosol was obtained by differential centrifugation, in which LDH activity was determined. It was found that LDH activity is significantly higher in the tissues of frogs from mountainous regions: by 42.4% in the muscles and 2.38 times in the liver (p 0.05). The high efficiency of catalysis is ensured due to significant changes in the catalytic parameters of the enzyme: an increase in Vmax (50.9% in muscles and 70% in the liver (p 0.05)) and a decrease in Km. (45.9% in muscles and 69% in liver, (p 0.05)). A more pronounced difference, compared to muscles, between LDH activity in the liver of foothill and lowland populations of frogs suggests that the sensitivity of liver LDH to changes in oxygen tension is higher. The vector of a number of other kinetic parameters of LDH (Ki, Sopt, Δ) in the liver of animals from mountainous landscapes is absolutely opposite to that of skeletal muscles. High activity and modifications of the catalytic properties of LDH in the tissues of marsh frogs living in mid-mountain areas may play an important role in the adaptation of these animals to conditions of oxygen deficiency.
TWO NEW SPECIES OF BRISTLETAILS OF THE FAMILY MACHILIDAE (MICROCORYPHIA) FROM THE ALTAI MOUNTAINS
Authors: Kaplin V. G.
Published: April 2024

Two new species of the bristletail family Machilidae are described: Ditrigoniophthalmus ongudaensis sp. n. and Allopsontus altaicus sp. n. The former, D. ongudaensis sp. n., differs from the known species of the genus Ditrigoniophthalmus Kaplin 1979 by the club-shaped paired ocelli, the relative lengths of the abdominal styli and urocoxites VIII and IX, and the basal and terminal portions of the penis in the male. Allopsontus altaicus sp. n. belongs to the subgenus Anisopsontus Mendes 1990 and is especially similar to the following four consubgeners: A. ciliatus (Wygodzinsky 1970), A. tekelensis Kaplin 2015, A. lineatus Kaplin 2002 and A. zinchenkoi Kaplin 2019. Yet, A. altaicus sp. n. differs in the number of articles of the ovipositor, the number of digging spines on its anterior and posterior gonapophyses, the number of rosette-shaped sensilla on the anterior femora of the male, the width to length ratios of paired ocelli in both sexes, the length to width ratios of the last article of the labial palps.
LITTORAL ICHTHYOFAUNA OF MATUA ISLAND, KURIL ISLANDS
Authors: Zheleznyak M. Yu.
Published: April 2024

As part of the XXI Kamchatka-Kuril expedition of the Russian Geographical Society, with the assistance of the Russian Federation Ministry of Defense, a survey of the littoral ichthyofauna of Matua Island was carried out in 2017. Fishes were caught by hand under stones in tidal pools and with a net during low tide. Fishing was performed in three areas: Cape Klyuv, Cape Yurlova, and Dvoynaya Bay. The fish caught were fixed in 6% formalin. Laboratory processing was carried out: the total length TL was measured with an accuracy of 1 mm, weighed with an accuracy of 0.1 g. Representatives of the families Cottidae, Hexagrammidae, Liparidae, Pholidae, Stichaeidae, Zoarcidae were found in the littoral areas. The size characteristics of the family representatives discovered, and the areas and depth of their capture were presented. In the littoral zone, we found a number of species previously not recorded from this area in the literature. The species compositions of the littoral ichthyofauna of Paramushir Island, Matua Island, Iturup Island, Shikotan Island and Kunashir Island were compared. Only the Stippled gunnel, Rhodymenichthys dolichogaster and the Frog sculpin, Myoxocephalus stelleri were found shared by all those islands. The ichthyofauna of Matua Island shows the greatest similarity to that of Paramushir Island.
NEW DATA ON THE DISTRIBUTION AND ISOTOPIC CHARACTERISTICS OF WOOLLY MAMMOTH REMAINS, MAMMUTHUS PRIMIGENIUS (PROBOSCIDEA, ELEPHANTIDAE), IN THE LATE PLEISTOCENE OF THE MINUSINSK DEPRESSION (SOUTH SIBERIA)
Authors: Malikov D. G. , Svyatko S. V. , Pyrayev A. N. , Kolobova K. A. , Ovchinnikov I. Yu. , Malikova E. L.
Published: April 2024

Radiocarbon dating of woolly mammoth remains from the Minusinsk Depression allows for the patterns of its distribution in southern Siberia in the Late Pleistocene to be specified. In the south of Siberia, mammoths are shown to have been most abundant in cold periods, the species having reached its maximum abundance in LGM. So far, there is no single mammoth record that would confidently refer to the warm time interval. During the warm intervals of the Late Pleistocene, the environment in southern Siberia could possibly have not favorable for the permanent habitation of the species Mammuthus primigenius. In general, the mammoths from the Minusinsk Depression retain species-specific features of the content of carbon and nitrogen stable isotopes (δ13C and δ15N) in bone collagen compared to other large herbivores. They show the highest δ15N values with the lowest δ13C, vs reindeer that, on the contrary, demonstrate the lowest δ15N values and a high δ13C. The isotopic signal of other herbivorous mammal species lies between the values of mammoths and reindeer. A comparison of the obtained data on carbon and nitrogen stable isotopes (δ13C and δ15N) of the woolly mammoth remains from the Minusinsk Depression with similar parameters in animals from the north of eastern Siberia reveals significant differences. One of the possible reasons may lie in differences in the diet of animals of the Minusinsk Depression from mammoths of other populations. However, similar trends, i.e. a relatively lower δ15N and higher δ13C content in the Late Pleistocene, are characteristic of both reindeer and woolly rhinoceroses of the Minusinsk Depression. This suggests that the differences in the carbon and nitrogen isotope composition in the Minusinsk Depression mammoths from those from the northern territories are due not only to the type of food, but also to a slightly different isotopic background of the region, associated with the local environment.
Heterometallic Carboxylate Complexes with {Co2Ln} and {Co2Li2} Metal Cores: Synthesis, Structures, and Magnetic Properties
Authors: Rubtsova I. K. , Nikolaevskii S. A. , Eremenko I. L. , Kiskin M. A.
Published: April 2024

The results of studying the heterometallic trinuclear {CoLn} and tetranuclear {CoLi2} carboxylate coordination compounds are systematized. The methods of the syntheses are discussed, and the structures and magnetic properties are considered
Grassland Monitoring Based on Geobotanical, Ground, Spectrometric and Satellite Data
Authors: Botvich I. Yu. , Kononova N. A. , Emelyanov D. V. , Pisman T. I.
Published: April 2024

The study assessed the possibility of grassland monitoring based on various spectral vegetation indices (NDVI, ClGreen, NDRE, NDMI) calculated according to Sentinel-2 satellite data during the 2018 growing season. Geobotanical studies and collection of ground-based spectrophotometry data were carried out simultaneously, at the same time of day, and were used as an additional stage of haymaking monitoring. It was possible to identify grasslands and determine the date of mowing based on ground and satellite spectrometric data. A drop in the indices (NDVI, clGreen, NDRE, NDMI) was observed on the date of mowing (25.07.2018). The possibility of grassland interpretation based on the NDVI index was proven reliable. It was shown that the dates of mowing determined according to satellite data were in good agreement with the ground dates of mowing (July 25th and August 27th). The spatial distribution maps of the NDVI index of grasslands according to Sentinel-2 satellite data for certain dates (June 18th, July 10th, and August 27th) were drawn. The resulting maps make it possible to identify grasslands and mowing dates in large areas.
Application of Landsat-8 Satellite Data to Predict Ore Mineralization for the Northern Territories on the Example of the Central Part of the Maloural Zone (The Polar Urals)
Authors: Ivanova J. N. , Nafigin I. O.
Published: April 2024

A new approach was developed during this study. It is focused on identifying probabilistic zones of increased fracturing (zones with a high density of lineaments), considered as a predictive feature for the localization of ore mineralization in the central part of the Malouralskaya zone (part the Polar Urals). This area is promising for the identification of ore occurrences of the polymetallic type (Fe, Cu, Cu–Zn, Au–Cu). Density maps of lineaments were built basis on the developed approach. In addition, predictive schemes for the distribution of highly permeable rock zones and promising areas for the polymetallic mineralization was identified, taking into account geological information, the distribution of mineral resources, and the outcome of remote sensing data processing. The last is based on identifying structures by manual and automatic approaches and their integration using the theory of fuzzy logic. Morphostructure maps were obtained from Landsat-8 data. These maps show that the known polymetallic ore occurrences in the region (Cu, Cu–Zn, Cu–Pb–Au, Fe–Ti–V, Cu–Pt) are located along the perimeter of a large morphostructure of the 1st order, or near extended tectonic structures for up to 20 km with mainly NE and less often NW trends. We identified six prospective zones by comparing remote sensing results with the geological map of the studied territory and known ore occurrences. The highlighted areas showed spatial consistency with several known polymetallic ore occurrences.
Optical Characteristics of Aerosol and Carbon Monoxide Content in the Atmosphere over the Irkutsk Region and Buryatia in 2010–2021
Authors: Rodionova N. V.
Published: April 2024

Seasonal and interannual variations of the aerosol optical depth (AOD) and the total carbon monoxide content in the atmospheric column have been determined by measurements of the MODIS and MOPITT instruments of the Terra satellite for several cities of the Irkutsk region and Buryatia with high level of atmospheric pollution for the period 2010–2021. For Irkutsk, a decrease of AOD interannual value from 0.278 in 2012 to 0.14 in 2020 with a general negative trend is shown. However, in 2021, the interannual AOD value for Irkutsk increased to 0.22. For Irkutsk, a negative trend of interannual variations in the total CO content in the atmospheric column is shown. When comparing the long-term seasonal variations of AOD according to ground measurements by CIMEL photometer in Tory (Buryatia), and the OMI/Aura satellite data, it was shown the proximity of AOD values for the summer and autumn seasons and a significant excess of AOT according to satellite data over ground measurements for the spring months. The largest Spearman correlation coefficient between ground and satellite measurements of AOD belongs to 2021 and is equal to ρs = 0.64.
Satellite Monitoring of Desertification in the Transitional Natural-Geographical Zone of the Volgograd Region
Authors: Silova V. A.
Published: April 2024

The northern part of the Volgograd Volga region is located in the transition zone from the Small Syrt to the Caspian lowland. This zone is characterized by a change in climatic conditions towards a decrease in the amount of precipitation and soil conditions, expressed in the transition from steppe to semi-desert soil types. This condition of the lands is due to the peculiarities of the physical and geographical conditions of the transition zone and the influence of economic activity. As a result of monitoring, it becomes possible to monitor the processes of their degradation, leading to a drop in soil fertility. The use of monitoring results will make it possible to plan measures to neutralize the consequences of their degradation. The main results of studies of degraded lands in the Volgograd Volga region were obtained on the basis of satellite images of Landsat 7, 8 over a twenty-year period. Based on the study of the dynamics of changes in areas subject to degradation, geoinformation mapping of degraded lands was carried out in the period from 1984 to 2020. Degradation assessment is carried out using geoinformation analysis tools and Earth remote sensing data in the research area. At the same time, changes in the area of degradation foci with a projective coverage of less than 10% were revealed, their spatial distribution was established, and the change in such an area over the period of research was established. The role of satellite images in the monitoring system is to timely establish changes in the state of the studied territory, including vegetation (projective cover), determine their area and spatial location, as well as clarify the geometric characteristics of research objects that can be identified on the displayed raster. The analysis of the state of the lands is carried out by the projective vegetation cover, which is most likely established by the tone of the image as the main characteristic of the satellite images raster and is identified into individual objects under study. Currently, due to the aridity of the climate on the territory of the Volgograd Volga region, low natural soil fertility, abnormal economic load, the process of land degradation continues (Tkachenko, Koshelev, 2019). Degradation foci with a projective coverage of less than 10% average over 150 thousand hectares. The growth of the area of such degradation sites is established in 1984, 1995, 1999, 2004, 2007, 2018, 2020 years . The area of degradation sites in the study area in some years exceeded 300 thousand hectares, which is 100% higher than the average for the entire time of research. In this regard, monitoring of the Volgograd Volga region is of great importance for the timely detection of land degradation processes in arid conditions and the development of measures for their rehabilitation.
Application of the Model of a Spatially-Hierarchical Quadtree with Truncated Branches to Improve the Accuracy of Image Classification
Authors: Dostovalova А. М.
Published: April 2024

The article considers the problem of increasing the accuracy of the classification of satellite image samples under the assumption that their samples are independent. The increase in accuracy was achieved by additional processing of the image as a spatially hierarchical quadtree, which is a type of random Markov field. A modification of this model was proposed – a spatially hierarchical quadtree with truncated branches. For the original and modified models, we compared the classification results of a real radar image characterized by a large amount of noise. The classification accuracy was estimated as the proportion of correctly classified pixels within the selected homogeneous areas. It has been established that within the framework of the modified model, homogeneous areas of images are more correctly classified by transferring the properties of accumulated images of the same region to them. The modified model makes it possible to obtain a classification result of higher accuracy than the original one when processing noisy images, while having less resource intensity.
Identification of Zones of Hydrothermally Altered Rocks Using WorldView-2 Data at the Talman Site (Talmanskaya Area, South-Eastern Transbaikal, Russia)
Authors: Ishmukhametova V. T. , Nafigin I. O. , Ustinov S. A. , Lapaev D. S. , Minaev V. A. , Petrov V. A.
Published: April 2024

The work is aimed at the practical application of satellite imagery data for the selection of promising areas for geological exploration in conditions of medium-low mountain relief and a sharply continental climate. The results of processing and analysis of WorldView-2 data within the Talmanskaya area are presented in order to identify zones of hydrothermal-metasomatic changes in rocks that are promising for the identification of gold-polymetallic mineralization. The choice of the study area is due to sufficient geological knowledge and the absence of technogenic formations that affect the result of processing satellite imagery materials. To increase the spectral information content of the WorldView-2 data, the spectral channel ratio method was used, as a result of which a pseudo-color RGB composite was created that displays the spectral characteristics of objects on the Earth’s day surface, in particular, minerals of the oxide/hydroxide group containing transitional iron ions (Fe3+ and Fe3+/Fe2+). Comparison of the results of processing satellite data along with geological information made it possible to identify spectral anomalies as indicators of the presence of near-ore changes, which are an important search criterion for hydrothermal deposits.
Investigation of the Possibilities of H-α Decomposition for Dual Polarization in Radar Monitoring of Afforestation
Authors: Dmitriev A. V. , Chimitdorzhiev T. N. , Kirbizhekova I. I. , Nomshiev Zh. D.
Published: April 2024

Assessment of the processes of afforestation and restoration of forests after fires is relevant for a significant territory of Russia, including the problem of carbon neutrality. The paper considers the possibilities of radar monitoring of the afforestation process based on the Cloud-Pottier decomposition of L-band data time series with dual polarization. Preliminary segmentation is based on the minimum values of the radar backscatter over the entire observation period. This makes it possible to distinguish treeless areas and sparsely wooded areas into a separate class, both existing before the start of the study and formed later. Next, Cloud-Pottier polarimetric decomposition is performed to obtain the parameters H (entropy) and α (scattering angle) and form time series from them. Studies have shown the principal possibility of afforestation dynamics monitoring on the H-α plane, where the points of the test areas form characteristic time tracks. A mature dense forest, whose characteristics are considered permanent, was used as a reference for estimating the changes rate on the H-α plane.
Dependence of the Vegetation of Winter Crops on the Relief and Soils in the East of the Stavropol Region
Authors: Doroshenko V. V.
Published: April 2024

In total, 7.444 fields with a total area of 857.9 thousand hectares were mapped on the territory of five eastern arid regions of the Stavropol Territory. As of 2021, arable land occupies more than 55% of the study area and is located mainly in its western part. Winter crops occupy 4.693 fields with a total area of more than 487 thousand hectares (56.9% of the total field area). Mapping of the contours of the fields was carried out on the basis of satellite images “Sentinel-2” (“natural colors”). The morphometric characteristics of the fields were calculated on the basis of the SRTM3 DEM. Mask of winter crops for the period 2011–2021 and weekly composites with data on the NDVI value for spring (March–May) were obtained using the Vega-Science service. The areas of the fields identified according to remote sensing data are comparable with official statistics. The fields are located on lands with a steepness of up to 5°, the steepness of 1°–2° prevails (about 90% of the total area). Most fields have a predominant southern exposure, there are no fields with a northern exposure. There are 13 kinds of soils on the territory of the study area, chestnut deep soils predominate. Average NDVI for March–May 2011–2021 It shows the highest values in fields located on meadow soils, the lowest NDVI values are observed on salt flats and salt marshes. It was revealed that the NDVI value decreases with increasing field size, the optimal field size is up to 150 hectares. The highest NDVI values were found in fields with a steepness of 1°–2°, southern exposure and meadow, chestnut and light chestnut soils. The influence of annual precipitation amounts on the NDVI value is analyzed.
Application of the Landsat-8 Data Set and the Digital Elevation Model SRTM to Prediction Gold-Polymetallic Mineralization to the Central Part of the Malouralskaya Zone, the Polar Urals
Authors: Ivanova J. N. , Nafigin I. O.
Published: April 2024

For the first time for the central part of the Malouralskaya zone of the Polar Urals, a new approach to processing data from remote sensing of the Earth was applied. The data were obtained using the Landsat-8 spacecraft. It consists in integration hydrothermal alteration propagation patterns and lineament density maps. They are based on the results of statistical processing of remote sensing data and digital elevation model SRTM (The Shuttle Radar Tpography Mission). The work was carried out in order to identify morphological features and patterns, features of the deep structure and identify promising areas of localization of gold-polymetallic mineralization in the study area. As a result of the study, it was found that areas promising for the gold-polymetallic type of mineralization in the central part of the Malouralskaya zone are localized within trans-regional fault zones, crossing favorable horizons and structures, and controlling ore mineralization, morphostructures, complicated by radial discontinuous faults of the 1st order NE and NW direction with a length of up to 30 km, as well as zones of increased indices II and III, less often hydroxide-(Al–OH, Mg–OH) and carbonate-containing minerals.
Study the Possibility of Precipitation Intensity Recovery from MTVZA-GYa Measurements
Authors: Sazonov D. S.
Published: April 2024

In this paper, we present an algorithm for restoring rain rate over the ocean according to the data of the microwave sounder MTVZA-GYa. The basis of the developed algorithm is the ALG'85 regression model, in which the scattering index on the high-frequency radiometric channel (~90 GHz) is used to estimate the intensity of precipitation. In this work, the scattering index was simulated based on the MTVZA-GYa data and compared with the GPM IMERG reanalysis data. To restore the rain rate, it is proposed to use a polynomial of the fourth degree. The obtained quantitative estimates show that the spread of RMS reaches 50%, and the correlation coefficient does not exceed 0.75. The qualitative comparison indicates a significant difference between the restored rain rate and the GPM IMERG data and the presence of a shift in the precipitation area. As a result of the analysis, it was concluded that one of the reasons may be the incorrect convergence of the beams of the radiation patterns for various frequency channels of the MTVZA-GYa device.
Use of Deep Learning and Cloud Services for Mapping Agricultural Fields on the Example on the Base of Remote Sensing Data of the Earth
Authors: Ermolaev N. R. , Yudin S. A. , Belobrov V. P. , Vedeshin L. A. , Shapovalov D. A
Published: April 2024

In recent years, research has been conducted in scientific institutions of the Ministry of Agriculture of the Russian Federation and the Russian Academy of Sciences on the introduction into practice of new technologies for the use of aerospace information in agriculture. The article, using the example of the Stavropol Territory, considers the possibility of using cloud services such as google earth engine (GEE) and Kaggle machine learning systems for mapping agricultural (agricultural) fields using deep learning methods based on remote sensing data. Median images of the Sentinel 2 space system for the 2022 growing season were used as data for the selection of training and validation samples. The total volume of the prepared training and training samples was 3998 images. One of the problems for researchers and manufacturers in the field of agricultural is the lack of centralized and verified sources of geospatial data. Deep learning methods are able to solve this problem by automating the task of digitizing the geometries of agricultural fields based on remote sensing data. One of the limitations in the widespread use of deep learning is its high demand for computing resources, which are not yet always available to a researcher or manufacturer in the field of agricultural. The paper describes the process of preparing the necessary data for working with a neural network, including correction and obtaining satellite images using the Google earth engine platform, their further standardization for training a neural network in the Kaggle service, and its further use locally. As part of the study, a neural network of the U-net architecture was used. The final classification quality was 97%. The threshold of division into classes according to the classification results was established empirically and amounted to 0.62. The proposed approach made it possible to significantly reduce the requirements for the local use of PC computing power. All the most resource-intensive processes related to the processing of satellite images were performed in the GEE system, and the learning process was transferred to the resources of the Kaggle system. The proposed combination of cloud services and deep learning methods can contribute to a wider spread of the use of modern technologies in agricultural production and scientific research.
Digital phased antenna array transceiver with multibeam radiation pattern
Authors: Guoming Lu , Zakharov P. N. , Korolev A. F.
Published: April 2024

A transceiver has been designed for the digital generation of a multibeam radiation pattern in this work. The transceiver consists of a transmitter and receiver, both are integrated on a single printed circuit board. The transceiver provides the formation of multiple beams in the far field of the radiation zone. The experimental measurement of the multibeam radiation pattern of a phased antenna array with a digital pattern synthesis was carried out.
Domain wall drift in single crystal plates with complex magnetic anisotropy
Authors: Mekhonoshin D. S. , Pamyatnykh L. A.
Published: April 2024

Numerical 2D simulating of static and dynamic structures of magnetic domain walls in a thick single-crystal plate-(111) with crystalline cubic and induced uniaxial magnetic anisotropy was performed. The domain wall drift in a low-frequency harmonic magnetic field was established, and the dynamic deformation of domain wall structure was revealed.
Growth and electron transport characteristics of epitaxial thin strontium iridate films
Authors: Moskal I. E. , Nagornykh K. E. , Petrzhik A. M. , Kislinsky Yu. V. , Konstantinyan K. I. , Shadrin A. V. , Ovsyannikov G. A.
Published: April 2024

The results of a study of epitaxial thin films of strontium iridate with the compositions Sr2IrO4 and SrIrO3 obtained by laser ablation and direct current cathode sputtering, respectively, are presented. Data on the growth technology, crystal structure, electrophysical parameters are given, and the activation energy for low-defect dielectric Sr2IrO4 films is calculated.
Synchrotron radiation-based works at the Novosibirsk research center
Authors: Zolotarev K. V. , Ancharov A. I. , Vinokurov Z. S. , Goldenberg B. G. , Darin F. A. , Kriventsov V. V. , Kulipanov G. N. , Cooper K. E. , Legkodymov A. A. , Lyubas G. A. , Nikolenko A. D. , Ten K. A. , Tolochko B. P. , Sharafutdinov M. R. , Shmakov A. N. , Levichev E. B. , Piminov P. A. , Zhuravlev A. N.
Published: April 2024

The Center for Collective Use “Siberian Center for Synchrotron and Terahertz Radiation” provides users from various organizations with the opportunity to use modern analytical techniques using synchrotron radiation beams for a wide range of research work. At present, the general direction of the development of new techniques is focused on the development of new original approaches to the use of synchrotron radiation.
On regularities of the formation of fractal structure on the surface of metal films of different thickness
Authors: Ivanov D. V. , Antonov A. S. , Kuz’min N. B. , Sdobnyakov N. Yu. , Afanasiev M. S.
Published: April 2024

The surface morphology of nanosized copper and nickel films on mica is studied using a scanning tunneling microscope. Altitude parameters and fractal dimension are determined for copper and nickel films of different thicknesses. The characteristic sizes of structural agglomerates for copper and nickel films are indicated depending on the thickness. The choice of the film thickness and the conditions for its production makes it possible to formulate recommendations for the development of the technology of “growing” structures with a given surface morphology.
Methods to increase the threshold pulsed magnetic field which causes destruction of a steel inductor under repeated impact
Authors: Russkikh P. A. , Boltachev G. Sh. , Paranin S. N.
Published: April 2024

Methods of increasing the pulsed magnetic field with an amplitude of about 40 T, which the cylindrical thick-walled inductor made of 30ХГСА steel can withstand without destruction under repeated impact, are considered. The methods include changing the material parameters, magnetic pulse characteristics, inner radius, creating a profile of resistivity decreasing from the inner surface deep into the material.
Investigation of electrophysical and mechanical parameters of piezoceramic materials for cartridge-type deformable mirrors
Authors: Toporovsky V. V. , Samarkin V. V. , Kudryashov A. V. , Galaktionov I. V. , Malykhin A. Yu. , Panich А. A.
Published: April 2024

We investigated electrophysical and mechanical parameters of the piezoceramic materials based on lead zirconate titanate. In correspondence with obtained data, modules with multilayer actuators with cross-section area of 4 × 4 mm, nominal displacement up to 4.3 µm and capacitance of the element with 12 nF for cartridge-type deformable mirror were produced.