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A new method for wireless byte-by-byte optical transmission of a digital signal multiplexed by the value of orbital angular momentum (OAM) of electromagnetic wave is presented. The transmitter is a round array of coherent laser beams formed by splitting original narrow-band laser radiation into eight channels. Data transmission channels with different OAM values are formed through interference combining of eight coherent laser beams in the far diffraction zone. The amplitude and phase of these beams vary proportionally to the values of Fourier images of information signals coming from the programmable controller to the amplitude and phase modulators of the round array of laser beams. The wave field propagates in space and comes at the input of the receiving telescope. To demultiplex the signal, the sorter of OAM modes is used. It comprises beam splitters, vortex phase plates, focusing lenses, photodetectors, and a comparator. The sorter distributes the incoming radiation into eight channels, which differ in the OAM values in the range from -3 to +4. Upon the processing, the structure of a digital signal byte is reconstructed at the vortex phase plates at the photodetectors inputs. The combining of eight laser beams in the comparator yields the complete structure of the transmitted digital signal. A conceptual diagram of an experimental setup implementing this method is proposed. The possibility of its practical implementation is demonstrated through numerical simulation. Some technical methods improving the efficiency of the method are suggested, and the advantages of the method are described.

Dependence on time and conditions of propagation of a laser beam integral (radius and displacement of the energy center) and local (intensity at a point) parameters was determined numerically. The obtained functions were expanded into a trigonometric Fourier series, and the precision of expansion was assessed. The mathematical models are presented as software applications, using which the dependence of the frequency of spectral components on the wind speed and the inner turbulence scale were derived. The results of the study can be used in the design of adaptive optics systems, in particular, for formulation of requirements for frequency of correction for atmospheric distortions, which is one of the main characteristics of laser beam control unit.

Results of a laboratory experiment with a laser beam propagated in an artificially created turbulence are analyzed. Methods are described which transform a sequence of video frames with recorded intensity distribution into characteristics of laser radiation. As a result of the expansion of time-dependent functions into a trigonometric Fourier series, the frequency of parameter variations was determined and requirements for the operating speed of an adaptive system designed to compensate for distortions were formulated.

The article analyzes the quality of collections of experimental vibrational-rotational energy levels and transitions of the main isotopologue of the water molecule placed in the information system (IS) W@DIS. Software for automatic support of the quality of the collection of energy levels and transitions when loading new data sources was created. This software performs sequential double filtering using the latest version of empirical energy levels, as well as quasi-empirical energy levels. A brief description of the introduced quasi-empirical energy levels and their role in updating the quality of data is given. Statistical data on each of the collections are presented, subsets of collections suitable for decomposition of expert wave numbers and lower-level energies are distinguished.

The data of the group and component composition of the ethanol extract of brown coal from the Tulgan deposit of brown coal in the South Ural basin are presented. It is shown by means of liquid chromatography, 13C NMR (CPMAS) spectroscopy, FT-IR spectroscopy, gas chromatography-mass spectrometry (GCMSD) that the extract contains: saturated and unsaturated hydrocarbons, alcohols, aromatic compounds, carboxylic acids and phenols. The following biologically active substances have been identified: 1-docosene; gamma-tocopherol; octadecanoic acid; ferruginol; eicosane; sugiol; beta-amyrin, concentrated mainly in the nonsaponifying fraction of the ethanol extract

This article presents the results of the permafrost research of the Oka Plateau in the Eastern Sayan Ridge. The complex of scientific research works carried out in the Sentsa River valley involved parametric drilling, geothermal regime observations in boreholes, cryolithological analysis of unconsolidated sediments, and petrographic studies of ground ice, as well as its structural and genetic features. It was established that the geological section down to 45 m consists of clays, clayey silts, silts and sands with ice interlayers and lenses. Permafrost thickness in the Sentsa River valley does not exceed 44 m, and a mean annual ground temperature at a depth of 10 m ranges from -1.1 to -2.1 °C. The parameters of the structure of ground ice indicate its segregation and injection origin. The stable multi-year positive trend in the mean annual air temperature on the Oka Plateau contributes to a gradual increase of the frozen sediments temperature in the layer of annual heat fluctuation, the destruction of ice-mineral frost mounds and the lowering of the surface.

The article presents the results of a study of the patterns and causes of heterogeneity in the cessation of runoff in October and the first half of November in the upper reaches of the mountain rivers of the Upper Kolyma. Three levels of heterogeneity were identified. The first level is associated with the diversity of geological terranes in the study area. The highest runoff values (annual layer, runoff modules in September and in the first winter month of October) are found in the area of the Viliginsky terrane which lithodynamic complex is dominated by tuffaceous rocks. The lowest values are observed in the Inyali-Debinsky terrain, where clayey and siliceous shales prevail. The second level of heterogeneity is expressed in the duration of runoff after the onset of the winter low water period, which varies from several days to 45 days. This is determined by the recharge of groundwater due to the melting of ice at the base of the seasonally thawed layer (STL). Consequently, the heterogeneity of this level is an indicator of water saturation of seasonally aquiferous sediments near the riverbed and of the ice content of the base of the seasonal aquifer. The third level of heterogeneity reflects the presence or absence of a water-absorbing talik above the hydrometric alignment.

The analysis of satellite imagery and field data allowed a reconstruction of gradual glacier shrinkage in the Tavan-Bogd transboundary massif (Altai) from the maximum of the Little Ice Age to 2024. Information on the glaciers has been obtained for the maximum of the Little Ice Age and the years 1968, 1977, 1989, 2000, 2010, 2020, and 2024. Since the Little Ice Age maximum, the area of the Tavan-Bogd glaciers decreased by 49 % whereas the firn line increased in altitude by 149 m, on average. An estimated volume of the glaciers decreased by 69.1-75.7 %. A vertical range of glaciation reduced by 330 m. Glacier shrinkage is accelerating which has manifested itself for the fronts of large valley glaciers after 2010, and for the total glaciation area since 2020, when area losses began to average 1.6 % per year. Contrasts in the aspect distribution of glaciers have increased, which may reflect an increase in the incoming solar radiation. Valley glaciers remain dominant in area, but their share in the total area has decreased. Accelerated glacier shrinkage appears to be a delayed response to an abrupt rise in summer temperatures during the 1990s.

Aufeis are widespread in the permafrost zone. Morphometric characteristics are indicators of the aufeis dynamics and can be used in theoretical research and for practical purposes. Their assessment is associated with technical difficulties, significant time and labor costs when using contact field methods. In this paper, we propose a technique for determining the area and volume of aufeis by aerial photography using post-processing of data from global navigation satellite systems. It makes it possible to achieve centimeter accuracy in determining altitude and plan coordinates. The areas and volumes of the object on the dates of surveys were calculated based on the data of field work at the Anmangyndinskaya aufeis during 2021-2023. A total of 21 aerial photographs were processed during both the formation and melting periods of aufeis using unmanned aerial systems and materials from high-precision ground geodetic profiles. The maximum ice volume varied from 6.71 million m³ on 30.03.2023 to 5.17 million m³ on 24.03.2022, and amounted to 5.41 million m³ on 24.05.2021. The calculated weighted average of ice thickness varies from 0.50 to 1.69 m. The mean error in determining the average aufeis thickness by aerial photography compared to ground-based geodetic measurements is 11 % after identifying and adjusting for the systematic error. A comparative analysis of the aufeis area was performed using Sentinel-2 satellite images and aerial photography. The error in determining the area using space images during the snow-free period is 11 %, and during the period of snow cover - 38 %.

Mark Mikhailovich Shatz, Candidate of Geographical Sciences, passed away on September 23, 2024, at the age of 81, after a long serious illness. He worked at the Melnikov Permafrost Institute in Yakutsk for several decades where he became a renowned specialist in the fields of regional geocryology, remote sensing of permafrost regions, and northern geoenvironmental studies. Dr. Shatz will be remembered as a remarkable permafrost researcher.