Nonmonotonic Decay of Nonequilibrium Polariton Condensate in Direct-Gap Semiconductors

Time evolution of a nonequilibrium polariton condensate has been studied in the framework of a microscopic approach. It has been shown that due to polariton-polariton scattering a significant condensate depletion takes place in a comparatively short time interval. The condensate decay occurs in the form of multiple echo signals. Distribution-function dynamics of noncondensate polaritons have been investigated. It has been shown that at the initial stage of evolution the distribution function has the form of a bell. Then oscillations arise in the contour of the distribution function, which further transform into small chaotic ripples. The appearance of a short-wavelength wing of the distribution function has been demonstrated. We have pointed out the enhancement and then partial extinction of the sharp extra peak arising within the time interval characterized by small values of polariton condensate density and its relatively slow changes.Comment: 20 pages, LaTeX 2.09; in press in PR

Post-Quantum Group Key Agreement Scheme

Progress in quantum technologies forces the development of new cryptographic primitives that are resistant to attacks of an adversary with a quantum computer. A large number of key establishment schemes have been proposed for two participants, but the area of group post-quantum key establishment schemes has not been studied a lot. Not so long ago, an isogeny-based key agreement scheme was proposed for three participants, based on a gradual increase in the degree of the key. We propose another principle for establishing a key for a group of participants using a tree-structure. The proposed key establishment scheme for four participants uses isogeny of elliptic curves as a mathematical tool

Innovative and technological development of the regions during the period of economic instability

Currently, the world economy has entered a period of unsteady development, characterized by the aggravation of problems that cannot be solved within the framework of existing equipment, technologies, management methods, etc. These problems are caused by the completion of the 5th technological order and the birth of the 6th, as well as the beginning of the 4th Industrial Revolution. The existing world experience convincingly proves that during periods of economic transformations caused by changes in technological structures, innovative development in the direction of innovative advance is a priority. The countries that have embarked on the path of advanced innovative development are the leaders of economic growth, ensuring the economic well-being and high quality of life of their peoples. For the enterprises of the domestic industry, which retains a significant innovative potential, the strategy of advanced innovation is virtually no alternative. The article examines the state of innovation and technological development of Russian regions during the period of economic instability. Attention is paid to the peculiarities of innovative growth of regions. Based on statistical data, the analysis of the main indicators reflecting the innovative activity of enterprises in the country’s industry is carried out. The main regional problems hindering innovative development are identified and a number of priority measures necessary for decision-making in the field of innovation promotion are proposed

Angle-resonant stimulated polariton amplifier

We experimentally demonstrate resonant coupling between photons and excitons in microcavities which can efficiently generate enormous single-pass optical gains approaching 100. This new parametric phenomenon appears as a sharp angular resonance of the incoming pump beam, at which the moving excitonic polaritons undergo very large changes in momentum. Ultrafast stimulated scattering is clearly identified from the exponential dependence on pump intensity. This device utilizes boson amplification induced by stimulated energy relaxation

Комплексный анализ процессов интеграции информационных технологий в медицинские организации

Nowadays Information Technologies (IT) are taking more and more stable position in the process of work organization in various companies, and particularly among medical organizations. Present-day scientific society has already begun to research the topic of IT integration particularities into the Health organizations. Current article is focused on this issue. Our team has planned and provided a systematic review to understand which barriers can appear in different medical centers during implementation of the innovative IT into working process. The review has been fulfilled according to the designed protocol based on the actual recommendations of Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. In the course of the workflow we have explored 2050 articles complied with the requirements. As a result, 23 key publications have been chosen and analyzed in detail. After considering the list of issues and barriers associated with the IT Implementation into hospitals and medical centers have been highlighted and described. We have classified them to notional clusters depending on the reasons of their appearance as well. In addition our team has defined the list of practical recommendations following which the result of the IT integration will be improved, but the risk of a negative outcome in the future can be eliminated.На современном этапе технологического развития информационные технологии (ИТ) закономерно занимают стабильную позицию в организации работы различных предприятий, в частности медицинских организаций. В мировом научном сообществе все больше внимания уделяется особенностям интеграции ИТ в медицинскую среду, на этом вопросе и сфокусировано внимание авторов данной статьи. Нашим научным коллективом был спланирован и проведен систематический обзор, целью которого было получить ответ на поставленный исследовательский вопрос: с какими проблемами могут столкнуться организации здравоохранения в процессе внедрения новых медицинских информационных технологий? Выполнение обзора осуществлялось по разработанному протоколу исследования в соответствии с актуальными рекомендациями Preferred Reporting Items for Systematic Reviews and Meta-Analyses: The PRISMA Statement. В ходе последовательно проведенных этапов работы из 2050 обнаруженных статей было отобрано 23 ключевых статьи и проведен их детальный анализ. В итоге были выделены, классифицированы и описаны барьеры, препятствующие успешному внедрению ИТ в учреждения здравоохранения. Кроме того, составлен список практических рекомендаций, выполнение которых, вероятно, приведет к повышению уровня внедрения технологии, а также позволит снизить риск непринятия технологии в долгосрочном периоде

Long-lived charged multiple-exciton complexes in strong magnetic fields

We consider the charged exciton complexes of an ideal two-dimensional electron-hole system in the limit of strong magnetic fields. A series of charged multiple-exciton states is identified and variational and finite-size exact diagonalization calculations are used to estimate their binding energies. We find that, because of a hidden symmetry, bound states of excitons and an additional electron cannot be created by direct optical absorption and, once created, have an infinite optical recombination lifetime. We also estimate the optical recombination rates when electron and hole layers are displaced and the hidden symmetry is violated.Comment: 12 pages + 2 PostScript figures, Revtex, Submitted to Phys. Rev. Let

Theory of neutral and charged exciton scattering with electrons in semiconductor quantum wells

Electron scattering on both neutral ($X$) and charged ($X^-$) excitons in quantum wells is studied theoretically. A microscopic model is presented, taking into account both elastic and dissociating scattering. The model is based on calculating the exciton-electron direct and exchange interaction matrix elements, from which we derive the exciton scattering rates. We find that for an electron density of $10^9 {\rm cm}^{-2}$ in a GaAs QW at $T=5K$, the $X^-$ linewidth due to electron scattering is roughly twice as large as that of the neutral exciton. This reflects both the $X^-$ larger interaction matrix elements compared with those of $X$, and their different dependence on the transferred momentum. Calculated reflection spectra can then be obtained by considering the three electronic excitations of the system, namely, the heavy-hole and light-hole 1S neutral excitons, and the heavy-hole 1S charged exciton, with the appropriate oscillator strengths.Comment: 18 pages, 12 figure

Development of Algorithm for Identification of Brucellosis Agent Cultures Using MALDI-TOF Mass-Spectrometry

Given are the results of direct protein profiling of brucella strain collection using matrix laser desorption/ionization time-of-flight mass-spectrometry (MALDI-TOF MS). Standardized is the method for brucellosis agent culture disinfection and subsequent assessment. Obtained are 59 representative protein profiles of six major species ( B. melitensis, B. abortus, B. canis, B. ovis, B. neotomae ), which are included into electronic database of mass-spectra, integrated in Biotyper v 3.0 software (Bruker Daltonics, Germany). Analysis of mass-spectra of brucella strains under investigation revealed 17 genus-specific fragments within the mass range of 2000-20000 Da, the combination of which can be used for Brucella spp . identification. In addition, described are the fragments, specific for certain brucella species and strains, promising as markers for intraspecific differentiation. Based on the data received developed is a standardized algorithm of identification and differentiation of brucellosis agent cultures applying MALDI-TOF mass spectrometry

Evaluation of the Analytical Capabilities of MALDI-TOF Mass Spectrometry in the Molecular Typing of <i>Bacillus anthracis</i>

The aim of the work was to compare the discriminating capacity of the canSNP13 genotyping and MALDI‑TOF mass spectrometry methods based on the results of the study of anthrax pathogen strains belonging to the two main genetic lines A and B.Materials and methods. 73 Bacillus anthracis strains from the collection of microorganisms of the Stavropol Research Anti-Plague Institute of the Rospotrebnadzor were investigated. Protein profiling was carried out using a Microflex mass spectrometer, data processing – in the environment of the statistical programming language “R”.Results and discussion. It has been experimentally confirmed that the proposed approach for differentiating proteotypes of B. anthracis strains with a discrimination index of 0.952 exceeds the one for the canSNP typing method and is comparable to the discrimination index for the MLVA31 method. The correlation of the results of strain clustering during typing by MALDI-TOF mass spectrometry and canSNP genotyping reaches 95 % as regards the division into the main genetic lines A and B. The studied strains of anthrax microbe, which mostly fall under phylogenetic groups of lineage A, represent more than a dozen protein profiles, which may be due to differences in the level of protein expression in strains of each canSNP genotype. MALDI-TOF mass spectrometry makes it possible to obtain the results comparable with genetic tests, has a better discriminating capacity compared to canSNP typing, and is easier to perform