Refraction laws for two-dimensional plasmons

Despite numerous applications of two-dimensional plasmons for electromagnetic energy manipulation at the nanoscale, their quantitative refraction and reflection laws (analogs of Fresnel formulas in optics) have not yet been established. This fact can be traced down to the strong non-locality of equations governing the 2d plasmon propagation. Here, we tackle this difficulty by direct solution of plasmon scattering problem with Wiener-Hopf technique. We obtain the reflection and transmission coefficients for 2d plasmons at the discontinuity of 2d conductivity at arbitrary incidence angle, for both gated and non-gated 2d systems. At a certain incidence angle, the absolute reflectivity has a pronounced dip reaching zero for gated plasmons. The dip is associated with wave passage causing no dynamic charge accumulation at the boundary. For all incidence angles, the reflection has a non-trivial phase different from zero and $\pi$

Life Histories of the Etnos Concept in Eurasia : An introduction

Peer reviewedPostprin

Ultralow-noise terahertz detection by p-n junctions in gapped bilayer graphene

Graphene shows a strong promise for detection of terahertz (THz) radiation due to its high carrier mobility, compatibility with on-chip waveguides and transistors, and small heat capacitance. At the same time, weak reaction of graphene's physical properties on the detected radiation can be traced down to the absence of band gap. Here, we study the effect of electrically-induced band gap on THz detection in graphene bilayer with split-gate p-n junction. We show that gap induction leads to simultaneous increase in current and voltage responsivities. At operating temperatures of ~25 K, the responsivity at 20 meV band gap is from 3 to 20 times larger than that in the gapless state. The maximum voltage responsivity of our devices at 0.13 THz illumination exceeds 50 kV/W, while the noise equivalent power falls down to 36 fW/Hz^0.5. These values set new records for semiconductor-based cryogenic terahertz detectors, and pave the way for efficient and fast terahertz detection

Migrants' Social-Cultural Adaptation Strategies from Central Asia in the Ural Megalopolis

The article states that that the majority of the immigrants continue to be foreigners in the culture of the Ural megalopolis, adhering to the lifestyle, traditions, and culture established in the country of origin. Two main strategies of migrants' sociocultural adaptation have been revealed: passive autarky (30.0%) and integrative (60.0%). The authors make the assumption that these people are more than the representatives of the first group integrated into Russian culture and are focused on long-term living in the Urals, despite the desire (40.0% of respondents) to return to their homeland. There is a lack of full assimilation of migrants in the host culture. Basically, there is no rejection of ties with Russian culture, but there is a willingness of the part of migrants to keep only their native culture. This was indicated by 10.0% of the surveyed migrants. The study revealed a new trend in the migrant environment - the desire to solve the problems that have arisen among migrants, with the help of compatriots who have remained in the country of origin through social networks. The research has revealed that there is the need to improve the social and legal support of migrants from the host community. If there is confidence in their legal security, then it motivates the migrant to comply with the norms of the Russian legislation and avoid cases of violation of their rights.В статье говорится о том, что по своему стилю жизни и культуре большая часть эмигрантов продолжает оставаться иностранцами в культуре уральского мегаполиса, придерживаясь стиля жизни, традиций, культуры, сложившихся в стране исхода. Выявлены две основные стратегии социокультурной адаптации мигрантов: пассивная автаркия (30,0%) и интегративная (60,0%). Авторы делают предположение о том, что именно эти люди в большей степени, чем представители первой группы, интегрированы в русскую культуру и ориентированы на длительное проживание на Урале, несмотря на желание (40,0% респондентов) вернуться на Родину. Полная ассимиляция мигрантов в принимающей их культуре практически не имеет места быть. В основном, отказа от связей с русской культурой не происходит, но существует готовность части мигрантов придерживаться лишь своей культуры. На это указало 10,0% опрошенных мигрантов. Исследование выявило новый тренд в мигрантской среде – стремление решать проблемы, возникшие у мигрантов, с помощью соотечественников, оставшихся в стране исхода посредством социальных сетей. В статье делается вывод о необходимости улучшения социально-правовой поддержки мигрантов со стороны принимающего сообщества. Если присутствует уверенность в своей правовой защищенности, то это мотивирует мигранта к соблюдению норм российского законодательства и избегать случаев нарушения своих прав

Tunnel field-effect transistors for sensitive terahertz detection

The rectification of electromagnetic waves to direct currents is a crucial process for energy harvesting, beyond-5G wireless communications, ultra-fast science, and observational astronomy. As the radiation frequency is raised to the sub-terahertz (THz) domain, ac-to-dc conversion by conventional electronics becomes challenging and requires alternative rectification protocols. Here we address this challenge by tunnel field-effect transistors made of bilayer graphene (BLG). Taking advantage of BLG's electrically tunable band structure, we create a lateral tunnel junction and couple it to an antenna exposed to THz radiation. The incoming radiation is then down-converted by the tunnel junction nonlinearity, resulting in high-responsivity (> 4 kV/W) and low-noise (0.2 pW/$\sqrt{\mathrm{Hz}}$}) detection. We demonstrate how switching from intraband Ohmic to interband tunneling regime can raise detectors' responsivity by few orders of magnitude, in agreement with the developed theory. Our work demonstrates a potential application of tunnel transistors for THz detection and reveals BLG as a promising platform therefor

Up-to-date opportunities of cervical lymph nodes ultrasound investigation in patients, suffering from oral cavity cancer

Background. Incidence of oral cancer in Russia is 4.52 and mortality – 2.44. Head and neck cancer is characterized by the high risk of development of metastases in regional lymph nodes. Lymph nodes status exerts influence on the treatment plan and appears to be the major predictive factor. Regional metastases result into two-fold decrease of five-year survival. Therefore, evaluation and treatment of metastatic lymph nodes is of prime importance. Objective. The aim of this manuscript was to illustrate and summarize publications devoted to modern methods of ultrasound evaluation of cervical lymph node status in patients with squamous cell carcinoma of the oral cavity. Results. Numerous studies have demonstrated, that standard ultrasound investigation (in B-mode) is characterized by high sensitivity and specificity (specificity varies from 71.0 to 96.4 %, and specificity – from 46.6 to 91.0 %, according to different studies). In addition, ultrasound efficiency exceeds that of CT. Accuracy of ultrasound as the method of cervical lymph node investigation has increased after implementation of such methods, as elastography and elastometry (this techniques allow to achieve sensitivity of 98.1 % and specificity of 100 %)