Observation of exchange Coulomb interactions in the quantum Hall state at nu=3

Coulomb exchange interactions of electrons in the nu=3 quantum Hall state are determined from two inter-Landau level spin-flip excitations measured by resonant inelastic light scattering. The two coupled collective excitations are linked to inter-Landau level spin-flip transitions arising from the N=0 and N=1 Landau levels. The strong repulsion between the two spin-flip modes in the long-wave limit is clearly manifested in spectra displaying Coulomb exchange contributions that are comparable to the exchange energy for the quantum Hall state at nu=1. Theoretical calculations within the Hartree-Fock approximation are in a good agreement with measured energies of spin-flip collective excitations.Comment: 5 pages, 3 figures, to appear in PRB Rapid Communication

Spin Polarizations at and about the Lowest Filled Landau Level

The spin polarization versus temperature at or near a fully filled lowest Landau level is explored for finite-size systems in a periodic rectangular geometry. Our results at $\nu=1$ which also include the finite-thickness correction are in good agreement with the experimental results. We also find that the interacting electron system results are in complete agreement with the results of the sigma model, i.e., skyrmions on a torus have a topological charge of $Q \ge 2$ and the Q=1 solution is like a single spin-flip excitation. Our results therefore provide direct evidence for the skyrmionic nature of the excitations at this filling factor.Comment: 4 pages, REVTEX, and 4 .ps files, To be published in Europhysics Letter

The key role of smooth impurity potential in formation of hole spectrum for p-Ge/Ge_{1-x}Si_x heterostructures in the quantum Hall regime

We have measured the temperature (0.1 <= T <= 15 K) and magnetic field (0 <= B <= 12 T) dependences of longitudinal and Hall resistivities for the p-Ge_0.93Si_0.07/Ge multilayers with different Ge layer widths 10 <= d_w <= 38 nm and hole densities p_s = (1-5)10^11 cm^-2. Two models for the long-range random impurity potential (the model with randomly distributed charged centers located outside the conducting layer and the model of the system with a spacer) are used for evaluation of the impurity potential fluctuation characteristics: the random potential amplitude, nonlinear screening length in vicinity of integer filling factors nu = 1 and nu = 2 and the background density of state (DOS). The described models are suitable for explanation of the unusually high value of DOS at nu = 1 and nu = 2, in contrast to the short-range impurity potential models. For half-integer filling factors the linear temperature dependence of the effective QHE plateau-to-plateau transition width nu_0(T) is observed in contrast to scaling behavior for systems with short-range disorder. The finite T -> 0 width of QHE transitions may be due to an effective low temperature screening of smooth random potential owing to Coulomb repulsion of electrons.Comment: Accepted for publication in Nanotechnolog

New mechanism of solution of the kTkT-problem in magnetobiology

The effect of ultralow-frequency or static magnetic and electric fields on biological processes is of huge interest for researchers due to the resonant change of the intensity of biochemical reactions although the energy in such fields is small. A simplified model to study the effect of the weak magnetic and electrical fields on fluctuation of the random ionic currents in blood and to solve the $k_BT$ problem in magnetobiology is suggested. The analytic expression for the kinetic energy of the molecules dissolved in certain liquid media is obtained. The values of the magnetic field leading to resonant effects in capillaries are estimated. The numerical estimates showed that the resonant values of the energy of molecular in the capillaries and aorta are different: under identical conditions a molecule of the aorta gets $10^{-9}$ times less energy than the molecules in blood capillaries. So the capillaries are very sensitive to the resonant effect, with an approach to the resonant value of the magnetic field strength, the average energy of the molecule localized in the capillary is increased by several orders of magnitude as compared to its thermal energy, this value of the energy is sufficient for the deterioration of the chemical bonds.Comment: 10 pages, Accepted to the Journal Central European Journal of Physic

Electron-phonon scattering at the intersection of two Landau levels

We predict a double-resonant feature in the magnetic field dependence of the phonon-mediated longitudinal conductivity $\sigma_{xx}$ of a two-subband quasi-two-dimensional electron system in a quantizing magnetic field. The two sharp peaks in $\sigma_{xx}$ appear when the energy separation between two Landau levels belonging to different size-quantization subbands is favorable for acoustic-phonon transitions. One-phonon and two-phonon mechanisms of electron conductivity are calculated and mutually compared. The phonon-mediated interaction between the intersecting Landau levels is considered and no avoided crossing is found at thermal equilibrium.Comment: 13 pages, 8 figure

Intrinsic Terahertz Plasmons and Magnetoplasmons in Large Scale Monolayer Graphene

We show that in graphene epitaxially grown on SiC the Drude absorption is transformed into a strong terahertz plasmonic peak due to natural nanoscale inhomogeneities, such as substrate terraces and wrinkles. The excitation of the plasmon modifies dramatically the magneto-optical response and in particular the Faraday rotation. This makes graphene a unique playground for plasmon-controlled magneto-optical phenomena thanks to a cyclotron mass 2 orders of magnitude smaller than in conventional plasmonic materials such as noble metals.Comment: to appear in Nano Letter

FORMATION OF CELLULAR STRUCTURES FOR MODELING AND EXPERIMENTAL EVALUATION OF PROPERTIES OF ADDITIVE MANUFACTURING PRODUCTS

The technique of modeling and experimental evaluation of effective physical and mechanical properties of additive manufacturing products obtained by layer-by-layer laser synthesis on the basis of powder alloys 07X18H12M2 (analog AISI 316L) and 08XN53BMTYU (analog Inconel 718), with the formation of cellular structures in them, is presented.Представлена методика моделирования и экспериментальной оценки эффективных физико.механических свойств изделий аддитивного производства, полученных методом послойного лазерного синтеза на базе порошковых сплавов 07Х18Н12М2 (аналог AISI 316L) и 08ХН53БМТЮ (аналог Inconel 718), с помощью формирования в них ячеистых структур.Исследование проведено в рамках государственного задания Министерства образования и науки Российской Федерации, проект № 11.6682.2017/8.9

ВНУТРИПУЗЫРНАЯ ТЕРАПИЯ РАКА МОЧЕВОГО ПУЗЫРЯ: СОВРЕМЕННОЕ СОСТОЯНИЕ ПРОБЛЕМЫ

Intravesical chemo/immunotherapy is a constituent of combination treatment for bladder cancer and widely used after transurethral resection of the tumor. The goal of intravesical therapy is to reduce the risk of a recurrence and progression of the disease, by exerting a direct cytotoxic effect on malignancy. The unique properties of the bladder make it possible to constantly improve the existing local therapy options and to develop novel ones, such as intravesical electrophoresis, local hyperthermia, gene therapy, and the use of penetrants and magnetic particles. The given review combines the physicochemical and pharmacokinetic properties of drugs, the histoarchitectonic features of the bladder, the present and future of intravesical therapy.Внутрипузырная химио-/иммунотерапия является составной частью комплексного лечения рака мочевого пузыря и широко применяется после трансуретральной резекции опухоли. Цель интравезикальной терапии состоит в снижении риска развития рецидива и прогрессии заболевания за счет прямого цитотоксического воздействия на злокачественное новообразование. Уникальные свойства мочевого пузыря позволяют постоянно совершенствовать существующие и создавать новые методы местного лечения, такие как внутрипузырный электрофорез, локальная гипертермия, генная терапия, применение веществ-пенетрантов и магнитных частиц. Представленный обзор объединяет физико-химические свойства и фармакокинетическую характеристику лекарств, особенности гистоархитектоники мочевого пузыря, настоящее и будущее внутрипузырной терапии

Комплексный подход к выбору терапии у пациентов с остеоартритом при первичном обращении к врачу. Консенсус экспертов (обзор литературы и резолюция)

Osteoarthritis (OA) is the most common pathology of the musculoskeletal system and is a serious medical and social problem. OA is of particular importance in elderly and senile people due to the high frequency of comorbid pathology. Pain relief is a priority in the formation of individual therapeutic programs for patients with OA, starting from their first request for medical assistance. At the same time, due to the ambiguity of existing clinical recommendations, most experts note a number of difficulties in prescribing treatment for patients with OA.The article presents a consensus position of experts regarding a complex approach to the choice of therapy in patients with OA at the initial visit to the doctor. The article discusses: current clinical guidelines for the management of patients with OA; most common problems in the management of patients with OA in real clinical practice; goals of treatment strategies for OA taking into account the risk factors for its progression; an algorithm of pain relief during initial treatment in patients with OA; prevention of OA exacerbations with the use of basic structure-modifying drugs; recommendations for the choice of non-steroidal anti-inflammatory drugs.According to experts, a rational approach to the treatment of OA is based on the combined use of non-drug and pharmacological methods with constant monitoring of therapy regimens and side effects. These recommendations can be considered disease-modifying strategies that in many cases allow improving functional status and achieving long-term remission in patients with OA.Остеоартрит (ОА) – наиболее распространенная патология опорно-двигательного аппарата, являющаяся серьезной медико-социальной проблемой. Особое значение ОА приобретает у лиц пожилого и старческого возраста из-за высокой частоты коморбидной патологии. Купирование болевого синдрома является приоритетным при формировании индивидуальных терапевтических программ для пациентов с ОА, начиная с момента их первичного обращения за медицинской помощью. Вместе с тем из-за неоднозначности существующих клинических рекомендаций большинство экспертов отмечают ряд сложностей при назначении лечения больным ОА.В статье представлена согласованная позиция экспертов, касающаяся комплексного подхода к выбору терапии у пациентов с ОА при первичном обращении к врачу. Рассмотрены имеющиеся на сегодняшний день клинические рекомендации по ведению пациентов с ОА, наиболее часто возникающие проблемы при курации больных ОА в реальной клинической практике, цели лечебных стратегий при ОА с учетом факторов риска его прогрессирования, алгоритм лечения боли у пациентов с ОА при первичном обращении и профилактики обострений ОА с использованием базисных структурно-модифицирующих препаратов, рекомендации по выбору нестероидных противовоспалительных препаратов.По мнению экспертов, рациональный подход к терапии ОА основан на комбинированном использовании немедикаментозных и фармакологических методов при постоянном мониторинге режимов терапии и побочных эффектов. Данные рекомендации можно рассматривать как болезнь-модифицирующие стратегии, позволяющие во многих случаях улучшить функциональный статус и добиться длительной ремиссии у пациентов с ОА