Quantum memory for light via stimulated off-resonant Raman process: beyond the three-level Lambda-scheme approximation

We consider a quantum memory scheme based on the conversion of a signal pulse into a long-lived spin coherence via stimulated off-resonant Raman process. For a storing medium consisting of alkali atoms, we have calculated the Autler-Townes resonance structure created by a strong control field. By taking into account the upper hyperfine states of the D1 optical transition, we show important deviations from the predictions of the usual three-level Lambda-scheme approximation and we demonstrate an enhancement of the process for particular detunings of the control. We estimate the memory efficiency one can obtain using this configuration.Comment: 8 pages, 6 figure

High frequency polarization switching of a thin ferroelectric film

We consider both experimentally and analytically the transient oscillatory process that arises when a rapid change in voltage is applied to a $Ba_xSr_{1-x}TiO_3$ ferroelectric thin film deposited on an $Mg0$ substrate. High frequency ($\approx 10^{8} rad/s$) polarization oscillations are observed in the ferroelectric sample. These can be understood using a simple field-polarization model. In particular we obtain analytic expressions for the oscillation frequency and the decay time of the polarization fluctuation in terms of the material parameters. These estimations agree well with the experimental results

Electromagnetically induced transparency in inhomogeneously broadened Lambda-transition with multiple excited levels

Electromagnetically induced transparency (EIT) has mainly been modelled for three-level systems. In particular, a considerable interest has been dedicated to the Lambda-configuration, with two ground states and one excited state. However, in the alkali-metal atoms, which are commonly used, hyperfine interaction in the excited state introduces several levels which simultaneously participate in the scattering process. When the Doppler broadening is comparable with the hyperfine splitting in the upper state, the three-level Lambda model does not reproduce the experimental results. Here we theoretically investigate the EIT in a hot vapor of alkali-metal atoms and demonstrate that it can be strongly reduced due to the presence of multiple excited levels. Given this model, we also show that a well-designed optical pumping enables to significantly recover the transparency

О ВОЗМОЖНОСТИ МЕЖДИСЦИПЛИНАРНОЙ ИНТЕГРАЦИИ РУССКОГО ЯЗЫКА И ХИМИИ В СТАРШИХ КЛАССАХ ОБЩЕОБРАЗОВАТЕЛЬНОЙ ШКОЛЫ

A study in the field of interdisciplinary interference of the Russian language and chemistry in high school.Проведено исследование в области междисциплинарной интеграции русского языка и химии в старших классах общеобразовательной школы

Local cellular immune response in chronic periodontitis

Microflora of the oral cavity forms a biofilm that induces response of immune system at the mucous membranes. Transition to periodontal lesion is provided by certain classes of resident mucosal immune cells and inflammatory/immune cells migrating to the periodont. In periodontal diseases, Th1, Th2, Th17, Treg are detected. T regulatory cells (Tregs) are proven to comprise the main anti-inflammatory cell population. Th17 cells and Treg cells play an important role in osteoclast differentiation. IL-17 secreted by Th17 cells affects osteoclastogenesis and may induce macrophages to enhance the local inflammatory response. In this regard, the aim of our work was to identify the local immune cells in oral cavity which are associated with severity of chronic generalized periodontitis. The oral cavity cells from 58 persons aged 38-65 years of both sexes in their mature age with a diagnosis of «chronic periodontitis» were examined by means of flow cytofluorometry. When determining levels of CD64+CD16+CD14- neutrophils in the patients with periodontitis of different severity, a statistically significant increase of this cell population was revealed upon development of this disease. In mild cases of periodontitis, a significant increase of relative CD64+CD16+CD14-  neutrophil contents was revealed (Me = 36.16%, p < 0.05) compared to the control group (Me = 7.7%, Q0.25 = 2.4%, Q0.75 = 12%). When assessing relative numbers of CD14+ monocytes in periodontitis of various severity, we revealed a significant increase in the number of these cells in severe cases. When studying levels of regulatory T lymphocytes (CD4+CD25+CD127low) in periodontitis of different severity, we revealed significantly decreased amounts of this cell population during development of the disease. In mild cases of periodontitis, a decreased level of CD4+CD25+CD127low cells (p < 0.05, Me = 1356 cells/ml) was revealed, as compared with control group (Me = 10666 cells/ml). Although the concentration of CD4+CD25+CD127low (Me = 4709 cells/ml) in the patients with moderate periodontitis was higher than the values in milder cases, the range of the main values was comparable and lower, than in control group. In severe periodontitis, a significantly decreased concentration of regulatory T lymphocytes was revealed (Me = 2637 cells/ml). These results confirm the anti-inflammatory regulatory function of Tregs. Understanding the osteo-immune mechanisms of bone remodeling control will help to understand the pathophysiology of accelerated bone loss observed in severe chronic periodontitis

Метрологическое обеспечение газовых калориметров и анализаторов числа Воббе

The paper describes research on metrological assurance of such measuring instruments as gas calorimeters and Wobbe index analysers. The purpose of the performed research is development of reference materials for gases with certified value of net volume-basis calorific value traceable to Russian state primary standard. Input set of candidate gases is hydrogen, methane, ethane and propane, as well as the target uncertainty of lower volumetric combustion energy value equal to 0,3 % – both were selected basing on results of metrological characteristics analysis of calorimetric equipment. The certified value of lower volumetric combustion energy is traceable to the State Primary Standard of combustion energy, specific combustion energy and volumetric combustion energy units GET 16. The certified value of selected gases and the uncertainty of this value were estimated with usage of comparing calorimeters for the combustion of high- and low-calorie gases «USVG» and «USNG» included in GET 16. Results obtained during investigational study and reference materials characterisation confirmed the stated accuracy. The continuance in prospect may allow development of reference materials for gas imitating mixtures of natural and casing-head gases as well as include Wobbe index in the list of certified characteristics.В статье рассматриваются вопросы метрологического обеспечения средств измерений – газовых калориметров и анализаторов числа Воббе. Цель проведенного исследования – разработка стандартных образцов газов с аттестованным значением низшей объемной энергии сгорания, прослеживаемым к государственному первичному эталону. Исходные чистые газы-кандидаты – водород, метан, этан и пропан, а также целевая неопределенность значения низшей объемной энергии сгорания – 0,3 %, были выбраны на основе результатов анализа метрологических характеристик парка калориметрического оборудования. Аттестованное значение низшей объёмной энергии сгорания прослеживается к государственному первичному эталону единиц энергии сгорания, удельной энергии сгорания и объемной энергии сгорания ГЭТ 16. Аттестованное значение для выбранных газов и его неопределенность были оценены с применением эталонных калориметров-компараторов для сжигания высоко- и низкокалорийных газов «УСВГ» и «УСНГ» из состава ГЭТ 16. Результаты, полученные в ходе экспериментальных исследований и характеризации стандартных образцов, подтвердили заявленные показатели точности. Продолжение исследований позволит в перспективе разработать стандартные образцы газовых смесей-имитаторов природного, попутного и других газов, а также включить число Воббе в список аттестуемых характеристик

Ferroelectric Nanotubes

We report the independent invention of ferroelectric nanotubes from groups in several countries. Devices have been made with three different materials: lead zirconate-titanate PbZr1-xTixO3 (PZT); barium titanate BaTiO3; and strontium bismuth tantalate SrBi2Ta2O9 (SBT). Several different deposition techniques have been used successfully, including misted CSD (chemical solution deposition) and pore wetting. Ferroelectric hysteresis and high optical nonlinearity have been demonstrated. The structures are analyzed via SEM, TEM, XRD, AFM (piezo-mode), and SHG. Applications to trenching in Si dynamic random access memories, ink-jet printers, and photonic devices are discussed. Ferroelectric filled pores as small as 20 nm in diameter have been studied

АНАЛИЗ И ДИАГНОСТИКА УРОВНЕЙ УЧЕБНО-ИНФОРМАЦИОННЫХ УМЕНИЙ СТУДЕНТОВ 1-ОГО КУРСА ЕСТЕСТВЕННО-НАУЧНОГО ФАКУЛЬТЕТА 2018–2019 ГОДА

This article diagnoses and analyzes the educational and information skills of first-year students. В данной статье диагностируются и анализируются учебно-информационные умения студентов первого курса.