Inverse exciton spin orientation due to trion formation in modulation doped quantum wells

Time-resolved and time-integrated circularly polarized photoluminescence of excitons and trions in external magnetic fields up to 10 T has been studied in undoped and n-type doped quantum well structures based on ZnSe. In an undoped structure, a circular polarization of photoluminescence induced by magnetic fields corresponded to the Boltzmann distribution of excitons on Zeeman sublevels. The inverse spin orientation of excitons is observed in doped samples with a carrier density of $3 \times 10^{10}$ cm$^{-2}$ and higher. Model calculations show that the reason for the inverse spin orientation is the effective depletion of the lowest-exciton Zeeman sublevel as a result of the spin-dependent formation of trions. The trion formation time as a result of exciton-electron binding was determined as 2 ps. This is noticeably shorter than the characteristic time of the exciton-photon interaction. The observed effect can be considered as a way of spin manipulation by electric fields.Comment: 5 pages,5 figure

Groups of S-units in hyperelliptic fields.

In this paper we calculate groups of S-units in hyperelliptic fields

S-units in hyperelliptic fields

In this note we represent some results about computation of the group of S-units in hyperelliptic fields. These results can have various applications, in particular in hyperelliptic cryptosystems

From the Laser Plume to the Laser Ceramics

The main stages of preparation of ceramic active elements of solid-state lasers are considered. The physical principles of laser synthesis of nanopowders are described. The features and processes taking place during compaction and compacts sintering are specified. Also we report on the investigation of characteristics of highly transparent ceramics on the basis of nanopowders synthesized in laser plume. It is shown that this approach enables to increase the “orange peel” formation threshold in the ceramics with strongly disordered crystalline structure. It opens the road to relatively simple synthesis technology from oxide materials and application of this ceramics as the gain media with oscillation efficiency higher than 50% and also leads to simplification of the synthesis technology of magnetoactive ceramics and to production of highly transparent YAG samples without the use of sintering heterovalent additives

About one discrete analog of Hausdorff semi-continuity of suitable mapping in a vector combinatorial problem with a parametric principle of optimality ("from Slater to lexicographic")

multicriteria linear combinatorial problem is considered, principle of optimality of which is defined by a partitioning of partial criteria onto groups with Slater preference relation within each group and the lexicographic preference relation between them. Quasistability of the problem is investigated. This type of stability is a discrete analog of Hausdorff lower semicontinuity of the many-valued mapping that defines the choice function. A formula of quasistability radius is derived for the case of metric $l_\infty.$ Some conditions of quasistability are stated as corollaries

Reducing the dose of mineral fertilizers using organomineral bionutrients

The results of work on the creation of a line of complex bionutrients mainly of organomineral synthesis and biological origin, based on physical methods of activation of known and long-used in agricultural practice products of metabolism of living organisms (animals- microorganisms- annelids), which, due to the activation of metabolic processes in plants, would enhance the immune status of plants and improve metabolic processes, thereby reducing the need for chemical pesticides and mineral fertilizers. The aim of the work was to study the effectiveness of the use of a bionutrient based on a combination of activated humates and organo-mineral compounds in a field experiment on winter wheat at various levels of mineral nutrition. It was found that the combined use of mineral fertilizers and bionutrients increased the yield of winter wheat by 22-23%. According to the impact on the yield of winter wheat, the use of bionutrients in the dry year of 2022 guaranteed and more effectively replaced the use of mineral fertilizers. With an increase in the dose of mineral fertilizers in winter wheat grain, the content of gluten and protein increased. A similar increase in the content of gluten and protein was noted in winter wheat grain treated with a bionutrient preparation. The combined use of NPK and bionutrient caused the highest content of gluten and protein in winter wheat grain. The use of the bionutrients contributed to an increase in ear productivity, improved overwintering and plant survival during the growing season, and increased plant resistance to Swedish fly infestation

Many-body corrections to the nuclear anapole moment II

The contribution of many-body effects to the nuclear anapole moment were studied earlier in [1]. Here, more accurate calculation of the many-body contributions is presented, which goes beyond the constant density approximation for them used in [1]. The effects of pairing are now included. The accuracy of the short range limit of the parity violating nuclear forces is discussed.Comment: 18 pages, LateX2e, 7 figure

Explanatory models for tick-borne disease incidence (Astrakhan rickettsial fever and Crimean-Congo hemorrhagic fever)

Introduction. The study focuses on methods providing mathematical substantiation of discrepancies between actual incidence rates of Astrakhan rickettsial fever (ARF) and Crimean-Congo hemorrhagic fever (CCHF) and predicted rates due to the indirect impact of weather conditions during the current epidemic season. The purpose of the study was to develop explanatory models for ARF and CCHF incidence using satellite monitoring (remote sensing) data and to present the results of their practical evaluation in the Stavropol Territory and Astrakhan Region. Materials and methods. The materials included climate data provided by the Space Research Institute of the Russian Academy of Sciences as well as epidemiological data on CCHF and ARF incidence from 2005 to 2021. The explanatory models incorporated the Bayes theorem and Wald sequential analysis. All the calculations were completed using the Microsoft Excel 2010-based program developed by the authors. Results. It has been found that the greatest indirect effect on development of the CCHF epidemiological situation is produced by the normalized difference vegetation index and relative air humidity in June-July in the Stavropol Territory and by the maximum, minimum and average air temperature in October as well as the minimum air temperature in July in the Astrakhan Region. ARF incidence rates depend on the indirect effect of the annual average and average annual maximum temperature, maximum temperature and the normalized difference vegetation index in April-July. The match between explanatory model-based results and prediction model-based results ranged within 46.2-100%. Discussion. In addition to projecting incidence rates, which could be reached with the observed values of climatic factors in the current year, the explanatory models can be used for indirect verification of prediction models and for identification of factors causing differences in results. Conclusion. The practical evaluation of explanatory models confirms the prospects and benefits of the study that should be continued, involving other regions highly endemic for tick-borne infections

A method of storing vector data in compressed form using clustering

The development of the machine learning algorithms for information search in recent years made it possible to represent text and multimodal documents in the form of vectors. These vector representations (embeddings) preserve the semantic content of documents and allow the search to be performed as the calculation of distance between vectors. Compressing embeddings can reduce the amount of memory they occupy and improve computational efficiency. The article discusses existing methods for compressing vector representations without loss of accuracy and with loss of accuracy. A method is proposed to reduce error by clustering vector representations using lossy compression. The essence of the method is in performing the preliminary clustering of vector representations, saving the centers of each cluster, and saving the coordinate value of each vector representation relative to the center of its cluster. Then, the centers of each cluster are compressed without loss of accuracy, and the resulting shifted vector representations are compressed with loss of accuracy. To restore the original vector representations, the coordinates of the center of the corresponding cluster are added to the coordinates of the displaced representation. The proposed method was tested on the fashion-mnist-784- euclidean and NYT-256-angular datasets. A comparison has been made of compressed vector representations with loss of accuracy by reducing the bit depth with vector representations compressed using the proposed method. With a slight (around 10 %) increase in the size of the compressed data, the absolute value of the error from loss of accuracy decreased by four and two times, respectively, for the tested sets. The developed method can be applied in tasks where it is necessary to store and process vector representations of multimodal documents, for example, in the development of search engines