On the microscopic theory of the exciton ring fragmentation

The description is presented for the dependence of the indirect exciton condensate density at the ring as a function of the polar angle at zero temperature with the involvement of the processes of formation and recombination of the excitons. In particular, starting from the quasi one-dimensional Gross-Pitaevskii equation with a spatially uniform generating term, we derive an exact analytical solution yielding the fragmentation of an exciton ring which is probably observed in the experiments.Comment: 4 pages, 1 figure. The preprint has been brought into accord with the journal's varian

Опыт применения азелаиновой кислоты в терапии больных акне

Treatment of acne is one of the important problems of modern dermatology. The goal of the research. The study of clinical efficacy and safety of the 15% azelaic acid in the form of Azelik-gel in the treatment of patients with papulo-pustular acne, mild to moderate in severity. Material and methods. Open comparative study of 8 weeks, which was attended by 75 patients. To assess the safety and efficacy of the therapy was performed clinical and biochemical blood and urine tests, evaluation of dermatological status, measurement of pH, moisture and oiliness of skin and analysis of DLQI. Results. 82% of patients receiving the Azelik-gel, marked clinical improvement or significant improvement. Conclusions. The results of the study indicate a high level of safety and tolerability of the Azelik-gel and obtained clinical results have shown its therapeutic efficacy in the treatment of papulo-pustular acne mild to moderate in severity.Лечение акне является одной из актуальных проблем современной дерматологии. Цель исследования. Изучение клинической эффективности и безопасности лекарственного препарата Азелик (15% гель азелаиновой кислоты) в терапии больных папуло-пустулезными акне легкой и средней степени тяжести. Материал и методы. Открытое сравнительное исследование продолжительностью 8 недель, в котором приняли участие 75 пациентов. Для оценки безопасности и эффективности проводимой терапии выполняли клинические и биохимические исследования крови и мочи, оценку дерматологического статуса, измерение рН, сальности и влажности кожи лица и анализ ДИКЖ. Результаты. у 82% больных, получающих гель Азелик, отмечено клиническое выздоровление или значительное улучшение. Выводы. Результаты проведенного исследования указывают на высокий уровень безопасности и хорошую переносимость геля Азелик, а полученные клинические результаты показали его терапевтическую эффективность в лечении папуло-пустулезной формы акне легкой и среднетяжелой степени

Long-lived magnetoexcitons in 2D-fermion system

The paper addresses the experimental technique that, when applied to a 2D-electron system in the integer quantum Hall regime with filling factor ν = 2 (the Hall insulating state), allows resonant excitation of magnetoexcitons, their detection, control of an ensemble of long-lived triplet excitons and investigation of their radiationless decay related to exciton spin relaxation into the ground state. The technique proposed enables independent control of photoexcited electrons and Fermi-holes using photoinduced resonance reflection spectra as well as estimate with a reasonable degree of accuracy the resulting density of photoinduced electron-hole pairs bound into magnetoexcitons. The mere existence of triplet excitons was directly established by inelastic light scattering spectra which were analyzed to determine the value of singlet-triplet exciton splitting. It was found that the lifetimes of triplet excitons conditioned by electron spin relaxation in highly perfect GaAs/AlGaAs heterostructures with highly mobile 2D electrons are extremely long exceeding 100  μs at T < 1 K. The paper presents a qualitative explanation of the long-spin relaxation lifetimes which are unprecedented for translation-invariant 2D systems. This enabled us to create sufficiently high concentrations of triplet magnetoexcitons, electrically neutral excitations following Bose–Einstein statistics, in a Fermi electron system and investigate their collective properties. At sufficiently high densities of triplet magnetoexcitons and low temperatures, T < 1 K, the degenerate magnetofermionic system exhibits condensation of the triplet magnetoexcitons into a qualitatively new collective state with unusual properties which occurs in the space of generalized moments (magnetic translation vectors). The occurrence of a condensed phase is accompanied with a significant decrease in the viscosity of the photoexcited system, which is responsible for electron spin transport at macroscopic distances, as well as with the effects of threshold enhancement of the system response to the external action of the electromagnetic field and emergence of a new intensive radiative recombination channel

Anisotropic physical properties of single crystal U2Rh2Sn in high magnetic fields

We report on the crystal and magnetic structures,magnetic, transport, and thermal properties of U2Rh2Sn single crystals studied in part in high magnetic fields up to 58 T. The material adopts a U3Si2 related tetragonal crystal structure and orders antiferromagnetically below TN 25 K. The antiferromagnetic structure is characterized by a propagation vector k 0,0,1 2 . The magnetism in U2Rh2Sn is found to be associated mainly with 5f states. However, both unpolarized and polarized neutron experiments reveal at low temperatures in zero field non negligible magnetic moments also on Rh sites. U moments of 0.50 2 amp; 956;B are directed along the tetragonal axis while Rh moments of 0.06 4 amp; 956;B form a noncollinear arrangement confined to the basal plane. The response to applied magnetic field is highly anisotropic. Above amp; 8764;15 K the easy magnetization direction is along the tetragonal axis. At lower temperatures, however, a stronger response is found perpendicular to the c axis. While for the a axis no magnetic phase transition is observed up to 58 T, for the field applied at 1.8 K along the tetragonal axis we observe above 22.5 T a field polarized state. A magnetic phase diagram for the field applied along the c axis is presented

Acoustic signatures of the phase transitions in the antiferromagnet U2Rh2Sn

We report on ultrasound measurements in a single crystal of the antiferromagnet U2Rh2Sn as a function of temperature and magnetic field. We find pronounced anomalies in the sound velocity at the N el temperature, 25 K, and at the field induced spin flop like transition at 22.5 T, which points to a strong magnetoelastic coupling. Additionally, we find that in the paramagnetic regime the temperature dependence of the magnetic susceptibility and the field dependences of the magnetization and sound velocity of transverse acoustic waves can be well described assuming a localized character of the 5f electrons. Using this premise, the crystal electric field scheme of U2Rh2Sn has been determine