Steep anomalous dispersion in coherently prepared Rb vapor

Steep dispersion of opposite signs in driven degenerate two-level atomic transitions have been predicted and observed on the D2 line of 87Rb in an optically thin vapor cell. The intensity dependence of the anomalous dispersion has been studied. The maximum observed value of anomalous dispersion [dn/dnu ~= -6x10^{-11}Hz^{-1}] corresponds to anegative group velocity V_g ~= -c/23000.Comment: 4 pages, 4 figure

Trust in distance learning during the COVID-19 pandemic: Evaluation of the quality of education of students and teachers of Russian universities

Introduction. The widespread transition of higher education institutions to distance learning during the COVID-19 pandemic contributed to a decrease in education quality ratings. These trends, against the background of forecasts of an increase in the share of “distance learning” in the educational process, may initiate an increase in social tension, as well as a decrease in the level of trust in the activities of authorities that do not fully ensure the maintenance of the quality of education in the new conditions. Aim. The aim of the article was to assess the quality of education in the context of distance learning, to analyse the consequences of the transformation of the practices of interaction between a teacher and a student. Methodology and research methods. An all-Russian comprehensive sociological study was conducted using the following methods: questionnaires and focus groups. The first wave of the study was a survey of students of higher educational institutions of economic orientation from 14 regions of the Russian Federation (the sample population was 6,500 students). During the second wave, the following projects were implemented: 1) a survey of students of economic universities from 17 regions of the Russian Federation (sample population = 7600); 2) a survey of teachers of the Financial University (sample population = 520); 3) focus groups with students. Results and scientific novelty. The results obtained allow the authors to draw the following conclusions: the remote format of classes during the quarantine restrictions did not cause a sharp drop in the quality of education. Meanwhile, students’ preferences demonstrate a commitment to the traditional form of education. The factors that shape the readiness of students for distance education (course of study, budget/contract form, direction of training) are identified. The main problem is related to the lack of face-to-face communication, which is interpreted by the authors not so much as an objective limitation of the remote format of work, but as a subjective unavailability, low adaptation of pedagogical and communicative practices to remote online interaction. The study showed the strengthening of the role of informal network interactions that ensure the filling of the information vacuum in conditions of uncertainty, the formation of trust. Practical significance. The research results and conclusions can be used for further theoretical and practical developments in this area, and can also become the basis for the preparation of methodological recommendations to reduce the negative consequences of the introduction of distance learning and improve the quality of education in the new environment.Введение. Повсеместный переход высших учебных заведений на дистанционное обучение в период пандемии способствовал снижению оценок качества образования. Данные тенденции на фоне прогнозов увеличения доли «дистанта» в образовательном процессе могут инициировать рост социальной напряженности, а также снижение уровня доверия к деятельности органов власти, которые не в полной мере обеспечивают поддержание качества образования в новых условиях. Цель статьи заключалась в оценке качества образования в условиях дистанционного обучения, анализе последствий трансформации практик взаимодействия педагога и студента. Методология и методы. Проведено всероссийское комплексное социологическое исследование с применением следующих методов: анкетирование и фокус-группы. Первая волна исследования представляла собой опрос студентов высших учебных заведений экономической направленности из 14 регионов Российской Федерации (выборочная совокупность составила 6 500 обучающихся). В период второй волны были реализованы: 1) опрос студентов вузов экономической направленности из 17 регионов Российской Федерации (выборочная совокупность = 7 600); 2) опрос преподавателей Финансового университета (выборочная совокупность = 520); 3) фокус-группы со студентами. Результаты и научная новизна. Полученные результаты позволяют сделать следующие выводы: дистанционный формат проведения занятий в период карантинных ограничений не вызвал резкого падения оценок качества образования. Но при этом студенты демонстрируют приверженность к традиционной форме обучения. Выявлены факторы, формирующие удовлетворенность студентов дистанционным обучением (курс обучения, бюджетная/контрактная форма, направление подготовки). Основная проблема связана с недостатком очного общения, что интерпретируется авторами не столько как объективное ограничение дистанционного формата работы, сколько как субъективная неготовность, низкая адаптация педагогических и коммуникативных практик к удаленному онлайн взаимодействию. Исследование показало усиление роли неформальных сетевых взаимодействий, обеспечивающих заполнение информационного вакуума в условиях неопределенности, формирование доверияПрактическая значимость. Полученные результаты и сделанные на их основе выводы могут быть использованы для дальнейших теоретических и практических разработок в данной сфере, а также могут стать основой для подготовки методических рекомендаций по снижению негативных последствий внедрения дистанционного обучения и повышению качества образования в новых условиях.The current research was carried out based on the results of studies carried out at the expense of budgetary funds under the state assignment of the Financial University under the Government of the Russian Federation.Исследование выполнено по результатам исследований, выполненных за счет бюджетных средств по государственному заданию Финансового университета при Правительстве РФ

Modelling of stratification and mixing of a gas mixture under the conditions of a severe accident with intervention of mitigating measures

International audienceOne of the objectives of the ERCOSAM-SAMARA projects was to assess capabilities of the current computational tools to predict the evolution of gas distribution in the containment under conditions relevant to a severe accident with hydrogen release. Various Lumped Parameter (LP) and CFD codes were used for the planning calculation, and pre- and post-test analyses. The planning calculations provided useful information for determining the most appropriate configurations, initial and boundary conditions used in the experiments. Pretest calculations were performed for nearly all the tests, using nominal initial and boundary conditions provided in the test protocols, which resulted in discrepancies for the pressurisation rate, due to a large (and unexpected) sensitivity of the results to the initial conditions. In general, all the codes were able to capture the stratification build-up. Regarding the last phase of the tests, the pressure trends were properly reproduced and the effectiveness of various mitigation devices on gas mixing was properly represented although large discrepancies remain between calculations and measurements. Finally, post-test simulations were carried out using the actual initial and boundary conditions, and making use of the knowledge on various phenomena acquired in the pre-test analyses. Although in general pressure and gas distribution evolution could be properly represented, various discrepancies between simulations and data show that the representation of some phenomena would require additional analysis and refined modelling

Heterodyne determination of the width of the emission lines of injection lasers in the beat frequency stabilization regime

A servo system was used to lock the beat frequency of injection lasers operating under conditions of self-stabilization of single-frequency emission in an anomalously wide continuous tuning range. The width of the beat spectrum was found to be ~500 Hz