Temperature-driven single-valley Dirac fermions in HgTe quantum wells

We report on temperature-dependent magnetospectroscopy of two HgTe/CdHgTe quantum wells below and above the critical well thickness $d_c$. Our results, obtained in magnetic fields up to 16 T and temperature range from 2 K to 150 K, clearly indicate a change of the band-gap energy with temperature. The quantum well wider than $d_c$ evidences a temperature-driven transition from topological insulator to semiconductor phases. At the critical temperature of 90 K, the merging of inter- and intra-band transitions in weak magnetic fields clearly specifies the formation of gapless state, revealing the appearance of single-valley massless Dirac fermions with velocity of $5.6\times10^5$ m$\times$s$^{-1}$. For both quantum wells, the energies extracted from experimental data are in good agreement with calculations on the basis of the 8-band Kane Hamiltonian with temperature-dependent parameters.Comment: 5 pages, 3 figures and Supplemental Materials (4 pages

Temperature-induced topological phase transition in HgTe quantum wells

We report a direct observation of temperature-induced topological phase transition between trivial and topological insulator in HgTe quantum well. By using a gated Hall bar device, we measure and represent Landau levels in fan charts at different temperatures and we follow the temperature evolution of a peculiar pair of "zero-mode" Landau levels, which split from the edge of electron-like and hole-like subbands. Their crossing at critical magnetic field $B_c$ is a characteristic of inverted band structure in the quantum well. By measuring the temperature dependence of $B_c$, we directly extract the critical temperature $T_c$, at which the bulk band-gap vanishes and the topological phase transition occurs. Above this critical temperature, the opening of a trivial gap is clearly observed.Comment: 5 pages + Supplemental Materials; Phys. Rev. Lett. (accepted

The conditions of injury when playing hockey

The article presents data from modern foreign and domestic scientific sources about the most common injuries when playing hockey, as well as measures to prevent injuries in this sport

Pain development and analgesia in athletes with ankle joints and ligaments injury

The pain feeling in athletes results from nociceptive and antinociceptive systems activity. Mostly pain follows injuries. Ankle joints and ligaments injury is one of the most often trauma. Pain intensity directly depends on the number of injured structures and the degree of the injury. Besides that pain intensity depends upon various factors such as gender and age. The history of injuries can increase the risk of repeated injuries and pain may become chronic. Psycho-emotional experiences during the competition can lead to pain without physical injuries. Anesthesia is important aspect in athletes’ life and it must be effective. Not all currently available medication are approved by the World Anti-Doping Agency. Every year “WADA Prohibited List” is reviewed and every athlete must follow it. The permitted and most effective methods of pain relief for joints and ligaments injury are cooling aerosols, non-steroidal anti-infl ammatory drugs and kinesio taping. Each of these methods has its own characteristics

Post-stroke incontinence of urine and feces: phenomenology, pathogenesis, principles of therapy

The paper presents neuroepidemiological data on the prevalence of post-stroke incontinence. Detailed questions the Central regulation of urination and defecation in norm and its violation in the context of acute and chronic cerebral ischemia. The described polymorphism of clinical manifestations of the syndrome of overactive bladder on the basis of the localization and the severity of ischemic damage to the cerebral centres of urination and defecation. First described the role of interhemispheric asymmetry and dominance of individual centers of urination in forecasting the course of the processes of reorganization of brain function and restore normal regulation of the pelvic organs in restorative and residual periods of ischemic stroke. For the first time describes the mechanisms of influence of different structure anticholinergics and p-sympathomimetic of Mirabegron on the basis of their points of application in the links 4 reflex retention of urine. The stages of the further study of pharmacological correction of post-stroke fecal incontinence.В работе представлены нейроэпидемиологические данные по распространенности постинсультного недержания мочи и кала. Детально изложены вопросы центральной регуляции акта мочеиспускания и дефекации в норме и ее нарушения в условиях острой и хронической церебральной ишемии. Описан полиморфизм клинических проявлений синдрома гиперактивного мочевого пузыря исходя из локализации и степени выраженности ишемического повреждения церебральных центров мочеиспускания и дефекации. Впервые описана роль межполрарной асимметрии и доминантности отдельных центров мочеиспускания в прогнозировании течения процессов реорганизации функции головного мозга и восстановления нормальной регуляции тазовых органов в восстановительном и резидуальном периодах ишемического инсульта. Впервые описаны механизмы влияния различных по строению антихолинергических средств и р-симпатомиметика мирабегрона, исходя из их точек приложения в звеньях 4-х рефлексов удержания мочи. Определены этапы дальнейшего изучения медикаментозной коррекции постинсультного недержания кала

Rehabilitation after stroke. The role of drug therapy

Of 400,000 strokes occuring in Russia every year, 75% are first and 25% repeated. The majority of cases (about 89%) are ischemic stroke, 17% are intracerebral hemorrhage, and about 3% - subarachnoid hemorrhage [10]. According to European studies, in every 100 000 of people there are 600 people who survived stroke, of which 60% remain disabled. Due to population aging the incidence of stroke is growing. Stroke prevention (including recurrent strokes) and rehabilitation of those who survived stroke has become an actual medical and social problem