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Blazars are active galactic nuclei (AGN) with relativistic jets whose non-thermal radiation is extremely variable on various timescales 1 – 3 . This variability seems mostly random, although some quasi-periodic oscillations (QPOs), implying systematic processes, have been reported in blazars and other AGN. QPOs with timescales of days or hours are especially rare 4 in AGN and their nature is highly debated, explained by emitting plasma moving helically inside the jet 5 , plasma instabilities 6 , 7 or orbital motion in an accretion disc 7 , 8 . Here we report results of intense optical and γ-ray flux monitoring of BL Lacertae (BL Lac) during a dramatic outburst in 2020 (ref.  9 ). BL Lac, the prototype of a subclass of blazars 10 , is powered by a 1.7 × 10 8  M Sun (ref.  11 ) black hole in an elliptical galaxy (distance = 313 megaparsecs (ref.  12 )). Our observations show QPOs of optical flux and linear polarization, and γ-ray flux, with cycles as short as approximately 13 h during the highest state of the outburst. The QPO properties match the expectations of current-driven kink instabilities 6 near a recollimation shock about 5 parsecs (pc) from the black hole in the wake of an apparent superluminal feature moving down the jet. Such a kink is apparent in a microwave Very Long Baseline Array (VLBA) image. Analysis of the optical and γ-ray flux monitoring of the blazar BL Lacertae during its outburst in 2020 shows the existence of quasi-periodic oscillations in the relativistic jet with cycles as short as 13 h.

The acoustical pollution in conditions of urban territories is rapidly increasing and causing a negative impact to the population and to the staff of industrial enterprises. The sources of environmental noise generations are analyzed. Transport and industrial plants may be considered as the main noise sources in the city environment. New results of research of environmental noise in urban conditions before, during and after COVID-19 period on the Samara region of Russia are presented. Experimental results of noise measurements caused by traffic movement and industrial enterprises operation are discussed. Comparison of results of environmental noise measurements in urban conditions before and during COVID-19 period shows that transport noise level was reduced, but the industrial noise level was almost the same, especially in low frequency range. Approaches to reduction of increased environmental noise levels in urban conditions are suggested.

Evolution of SARS-CoV-2 in immunocompromised hosts may result in novel variants with changed properties. While escape from humoral immunity certainly contributes to intra-host evolution, escape from cellular immunity is poorly understood. Here, we report a case of long-term COVID-19 in an immunocompromised patient with non-Hodgkin’s lymphoma who received treatment with rituximab and lacked neutralizing antibodies. Over the 318 days of the disease, the SARS-CoV-2 genome gained a total of 40 changes, 34 of which were present by the end of the study period. Among the acquired mutations, 12 reduced or prevented the binding of known immunogenic SARS-CoV-2 HLA class I antigens. By experimentally assessing the effect of a subset of the escape mutations, we show that they resulted in a loss of as much as ~1% of effector CD8 T cell response. Our results indicate that CD8 T cell escape represents a major underappreciated contributor to SARS-CoV-2 evolution in humans. Here, the authors report accelerated intrahost evolution of SARS-CoV-2 in an immunocompromised patient with non-Hodgkin’s lymphoma with 318 days long COVID-19, and show that changes in the viral genome resulted in escape from T cellular immune response.

The objective of these studies was to determine the dependence of the distribution of the microwave field into a grain layer and the efficiency of energy transfer from the magnetron into the grain layer, via a waveguide, on the moisture content. The subject of the research was a semicircular waveguide with slot radiators that supply a microwave field to the grain surrounding the waveguide. The change in the directional diagram of the microwave field in the longitudinal direction of the waveguide was studied using CST Microwave Studio 2019 software. It was found that the change in the moisture content of the processed grain leads to a significant change in both the radiation and total efficiency values of the waveguide. For instance, the radiation efficiency of the waveguide decreases by 15.1% (from 68.729 dB to 58.294 dB) when the moisture content of the processed grain increases from 14% to 26%. The total radiation efficiency also decreases (from 11.27 dB to 21.7 dB). In this case, not only the value of the radiation efficiency but also the shape of its dependence on the magnetron radiation frequency change. The results of this study enable the formulation of a requirement for a selective approach to the alignment of emitting waveguides depending on the moisture content of the processed grain. Data were obtained on the change in the Q-factor for resonators in which grain layers are processed, depending on the variation in grain moisture content. The research results suggest that when designing microwave convective zones for grain processing, the quality factor of the resonator should not be considered as the primary parameter. The main focus should be on maximizing the radiation efficiency of the waveguides.

The microwave field is used for drying and disinfecting grains during the pre-sowing seed treatment. The use of a microwave field in these installations leads to an increase in their productivity and a decrease in the energy consumed by them. In grain dryers, where the grain moves in a dense layer without being loosened, one of the challenges in using microwave fields is ensuring sufficient uniformity of the field distribution. In this article, waveguide design options that introduce microwave radiation into the grain layer are discussed. The objective of this study was to use application software to find the optimum type of transmitter from the three options presented. A mathematical simulation of the electromagnetic field distribution was performed with the use of CST Microwave Studio software 2019 in order to evaluate and compare horn-type, rectangular, and semicircular waveguides. The data on the standing wave ratio and radiation efficiency of these types of waveguides have been reported. The specific features of the microwave electromagnetic field distribution and radiation power in the output of these waveguides have been described. The results of mathematical simulations revealed that semicircular waveguides with slot-type radiators are preferable for processing dense grain layers.

Analysis of a great number of works allows concluding that many types of GTE and GTU nozzles can be divided into 3 main groups and 3 intermediate (composite) groups. The developed general classification of atomizers with descriptions of their operating principles, advantages and disadvantages is used to select a type of device for development. The most promising type chosen from descriptions given in the paper is the one with atomization of fuel by high-speed air flow.

During the drought season agronomic crops get into a critical situation when a lack of moisture and nutritional chemicals may lead to a wilt of plants and crop loss. For preventing of the following situation it is proposed to apply liquid ameliorants in the process of subsurface tillage which can accumulate moisture in a soil. The introduction of ameliorants offered to carry out work on liquid ameliorants directly into the root soil layer, to create favorable conditions for the development of the plant. Also, when making soil ameliorants preventing the leaching of their streams generated from rainfall and meltwater. Experimental studies have shown that zero tillage with simultaneous application of liquid ameliorants (in the process of experiment was used urea-ammonium nitrate) can increase soil moisture at cultivation depth from 22 to 47%. Moisture of soil determined after two months after cultivation and applying of liquid ameliorants according to the National Standard 28268-89 \"Soils. Methods for determination of moisture, maximum hydroscopic moisture and moisture of steady plant fading\". In this case, received values of filtration filters and soil porosity show qualitative soil cultivation for crop growing.

We consider the discrete Dirichlet boundary value problem for a discrete elliptic pseudodifferential equation in the quadrant and study its solvability in discrete counterparts of the Sobolev–Slobodetskii space. The study is based on a special factorization of the elliptic symbol. We compare the solutions to the discrete Dirichlet problem and its continuous counterpart.

Environmental noise impact is increasing every year and may cause serious negative problems for inhabitants of urban territories and for specially protected natural areas. Industrial noise is one of the main noise sources of the urban territories of modern towns. On the territory of Togliatti city of Russia the part of the Middle Volga Integrated Biosphere Reserve is located. Results of analysis of environmental noise sources on the territory of north industrial unit of Togliatti city are considered. Methods of analysis of environmental noise in Russia are analysed. Results of measurements of environmental noise in the zone of north industrial unit of Togliatti city are presented. Practically in all noise measuring the exceeding noise values were determined. Measurement results of noise characteristic directly in the territories of industrial enterprises are showing that the main noise sources, especially in low frequency range, are power plants. Noise map of the territory of the north industrial unit of Togliatti city have been developed. In total, it is possible to make a conclusion about the existing of real problem of increased noise impact of industrial enterprises to the population.

The scientific article considers the impact of the error of circular control methods on assessing the quality of anti-erosion soil tillage on slope lands. The applied control methods are implemented in scientifically based designs of technical control facilities that can provide high measuring accuracy of the parameters, when profiling the soil surface for different slopes of the agricultural landscape of slope lands. It was found that the device error along the measurement path is negligible, since it is theoretically possible to set the scanning angle of 60 or more degrees, while the radial error is restrained, which does not allow setting such limits of angles even when the device arm length is 0.5 m. On the bases of the results of analytical studies, we obtained a graph of changes of the surface width being measured after the passage of the working part, depending on the scanning angle when the mechanism vibrates. The analysis of the graph allows us to conclude that in order to scan the underlying surface in case the working part width of the anti-erosion machine is known or can be predicted within the acceptable error values, it is necessary to change the radius of the scanned circle by changing the arm length. For example, when working part width is less than 0.5 meters, you can use any circle radii. If the width of soil tillage - from 0.5 meters to 1 meter, the circle radius should be more than 0.7 m and the scanning angle should be less than 50 degrees. When the width of the working part of more than 1 meter the circle radius should be about 3 meters that slightly complicates the design of the device since the diameter reaches almost 6 meters.