Magnetic field study of exciton nonradiative broadening excitation spectra in GaAs/AlGaAs quantum wells

Exciton excited states in the quantum well are studied via their effect on the nonradiative broadening of the ground exciton resonance. Dependence of the nonradiative broadening of the ground exciton state on the photon energy of additional laser excitation was measured. Applying magnetic field up to 6 T, we could trace the formation of Landau levels and evolution of the exciton states of size quantization in a 14-nm GaAs/AlGaAs quantum well. Sensitivity of the technique allowed for observation of the second exciton state of size quantization, unavailable for conventional reflectance and photoluminescence spectroscopy. Our interpretation is supported by the numerical calculation of the exciton energies of the heavy-hole and light-hole subsystems. The numerical problems were solved using the finite-difference method on the nonuniform grid. The ground Landau level of the free electron-hole pair was observed and numerically analysed. In addition to energies of the excited states, electron hole distances and exciton-light interaction constant was investigated using the obtained in the numerical procedure exciton wave functions

Toward an Ecological Perspective of Interethnic Ideologies: Moderation Effects of Ethnic Density on Relationships between Interethnic Ideologies and Intergroup Bias

Introduction. In this exploratory study, we examined several interethnic ideologies held by individuals (assimilation, colorblindness, multiculturalism, and polyculturalism) from a social ecological perspective. We examined moderation effects of neighborhood ethnic density (ED) on relationships between interethnic ideologies and intergroup bias towards various minority ethnic groups in the Russian context. Intergroup bias was assessed as a composite score of bias toward four ethnic groups who have different cultural distances from the Russian mainstream population: Chechens, Belarusians, Uzbeks, and Chinese. Method. We obtained a gender balanced sample of ethnic Russians from the Central Federal District of Russia (N = 359) comprising of 47% women and 53% men. The measures were used in a Russian translation by an adaptation using the back-translation and cognitive interviews. Multiple regression analysis was used to test the relationships. Results. The results showed that high perceived neighborhood non-Russian ED weakened negative relations between intergroup bias and ideologies that purportedly accept cultural diversity (multiculturalism and polyculturalism). On the other hand, for interethnic ideologies those purportedly reject cultural diversity, high perceived neighborhood non-Russian ED weakened the positive relations between intergroup bias and assimilation and strengthened the negative relations between intergroup bias and colorblindness. Summary and Conclusions. The pattern of results suggests that the relationship between attitudes and intergroup bias may change based on the perceived ethnic composition of the local area and frequency of contacts. Although our findings are relatively novel they support the emerging view that attitudes and intergroup relations need to be studied from a social ecological context

Неотложная рентгенэндоваскулярная тромбаспирация при ишемическом кардиоэмболическом инсульте

A case report of successful intravascular aspiration in a patient with acute cardioembolic stroke is presented. Non-occlusive critical thrombosis of the extracranial segment of the left internal carotid artery with distal total embolization of the medial cerebral artery was verified. During the intervention, the dislocation of thrombotic masses into the supraclinoid segment occurred.Представлено клиническое наблюдение успешной внутрисосудистой аспирации у пациента с острым ишемическим инсультом кардиоэмболического генеза. Верифицирован неокклюзивный критический тромбоз экстракраниального сегмента левой внутренней сонной артерии с дистальной тотальной эмболизацией средней мозговой артерии. В ходе проведения вмешательства произошла дислокация тромботических масс в супраклиноидный сегмент

Digital smile design: selecting the optimal program for students

the article presents an analysis of programs that allow you to make a digital smile design. As a result of the study, the Visagi-Smile program was chosen as the most suitable for introduction into the teaching process of the dental faculty.В статье представлен анализ программ, позволяющих осуществить цифровой дизайн улыбки. В результате проведенного исследования выбрана программа Visagi-Smile, как наиболее подходящая для внедрения в процесс обучения студентов стоматологического факультет

Applying digital technologies and “gold ratio” principle for evaluating the abrasion of the front teeth group

Based on the “golden ratio” principle, the article considers the possibility of using photometric analysis and computer technology to diagnose tooth abrasion. Based on the analysis of a number of scientific articles on the introduction of digital technologies in dentistry at present, approaches to their use in the practice of a dentist are analyzed. The applications of the ideal proportion in various fields and its integration into the modern diagnosis of patients with a dental profile are investigated. The study obtained the results of a photoanalysis of patients and an assessment of their dental status, in particular, the pathology under consideration.На основании правила “золотого сечения” в статье рассматривается возможность применения фотометрического анализа и компьютерных технологий для диагностики стираемости зубов. На материале анализа ряда научных статей, посвященным внедрению цифровых технологий в стоматологию в настоящее время, анализируются подходы к применению их в практике врача стоматолога-терапевта. Исследуются применения идеальной пропорции в различных областях и ее интеграция в современную диагностику пациентов стоматологического профиля. В ходе исследования получены результаты фото-анализа пациентов и оценка их стоматологического статуса, в частности, рассматриваемой патологи

Electrocardiographic diagnostics of cardiovascular pathology in athletes of youth sports schools

Objective: to evaluate the data of cardiac screening to identify cardiac pathology and determine sports participation among in athletes of Youth Sports Schools in five districts of St. Petersburg. Materials and methods: 9847 young athletes (average age 13.8 ± 4.9 years, 6127 men) were included in the study during 8 months. Clinical protocol uncluded the collection of complaints, anamnesis, family anamnesis, physical examination, ECG in 12 leads. If necessary, Holter monitoring, echocardiography, and an exercise test were performed. Results: typical ECG changes were registered in 60.4% of athletes, borderline in 0.05% and pathological in 3.69%. All athletes with pathological changes were excluded from the training and competitive process for the period of in-depth medical examination. In the end, two athletes were not allowed to continue participation in sport (2 with stressful ventricular arrhythmias). There was not any lethal outcomes for the entire period of the study. Conclusions: cardiological screening using the routine ECG method remains the main tool for identifying a possible pathological substrate and assessing the risk of sudden cardiac death. Early detection of cardiac arrhythmias and conduction disturbances allow to take measures to prevent sudden cardiac death

Evaluation of the Effectiveness of VEGF Effect on the Regeneration of the Anterior Tracheal Surface in the Early Postoperative Period

Background. Violation of the regeneration of the tracheal wall after undergoing reconstructive surgeries remains an urgent problem of modern surgery. One of the reasons for the violation of the regeneration processes is insufficient blood supply to the organ. Finding new ways to improve blood flow is a promising area of research.Aim. To evaluate the effectiveness of VEGF effect on the regeneration of the anterior tracheal surface in the early postoperative period.Materials and methods. The study included 60 male Wistar rats at the age of 10 months. All animals underwent tracheal reconstructive surgery; the animals were divided into three groups: group 1 – without medicinal film, group 2 – with prolonged-release medicinal film, group 3 – with prolonged-release medicinal film containing VEGF. The sampling of histological material was carried out on days 3, 7 and 21 of the study, using morphometry to determine the thickness of the tracheal wall, the thickness of the postoperative scar, the area of the surgical intervention zone, the area of the vessels, the ratio of the thickness of the postoperative scar to the wall thickness trachea and the ratio of the area of the vessels to the area of the surgical intervention zone.Results. It was revealed that when exposed to a long-acting medicinal film containing VEGF, significant histological changes occurred on day 7 of the study. In groups 1 and 2, healing occurred by day 21 and was accompanied by defects of the mucous membrane and cartilage. On day 7 in group 3, there was a complete epithelialization of the tracheal wall, an increase in the number of newly formed vessels and glands in the area of surgical intervention. Healing was carried out with a thin postoperative scar without defects in all layers of the tracheal wall.Conclusion. The results obtained indicate the stimulating effect of VEGF on the regeneration of the tracheal wall in the early postoperative period after undergoing reconstructive surgery. The use of VEGF reduces the time of postoperative wound healing and preserves the anatomical structure of the tracheal wall