Low-field diffusion magneto-thermopower of a high mobility two-dimensional electron gas

The low magnetic field diffusion thermopower of a high mobility GaAs-heterostructure has been measured directly on an electrostatically defined micron-scale Hall-bar structure at low temperature (T = 1.6 K) in the low magnetic field regime (B < 1.2 T) where delocalized quantum Hall states do not influence the measurements. The sample design allowed the determination of the field dependence of the thermopower both parallel and perpendicular to the temperature gradient, denoted respectively by Sxx (longitudinal thermopower) and Syx (Nernst-Ettinghausen coefficient). The experimental data show clear oscillations in Sxx and Syx due to the formation of Landau levels for 0.3 T < B < 1.2 T and reveal that Syx is approximately 120 times larger than Sxx at a magnetic field of 1 T, which agrees well with the theoretical prediction.Comment: 4 pages, 4 figure

Evaluation OF adherence to various treatment methods among osteoarthritis patients

This article describes the results of questioning which was carried out in 2007 — 2008 years in order to estimate adherence to various treatment methods among the patients with knee and hip osteoarthritis (OA). The 54 patients were randomly selected and questioned in 9 general practices in the city of Yekaterinburg and in the Sverdlovsk region. The analysis of demographic data has confirmed relation between OA and gender (88,8% of participants were females) and increased body mass index (average BMI was 32±6,8 kg/m2) as risk factors of OA. Statistically significant connection has been found out between age of 55 and older and increased adherence to local thermal procedures (Cl 0,07-0,73), fangotherapy and medical baths (Cl 0,07-0,96). The majority of patients preferred to use medical interventions several times a month or as needed, meanwhile adherence to daily treatment was low. Revealed data demonstrate high level of NSAID usage as in tablets, as in topical forms, and also high adherence to topical treatment in general. Participants have demonstrated relatively low adherence to weight reduction and exercises, but parapharmaceutics and complementary medicines are very popular. Moreover, significant amount (31,1%) of ungrounded X-ray examinations of knee joints has been found out. Thus, research has shown that diagnostics and treatment of OA in primary care are far from optimal; this situation can be caused by the outdated clinico-organizational standards, insufficient interaction between physicians and patients, and also with difficulties in behavioural stereotypes change and preference of more simple, cheap and accessible methods of treatment among OA patients.В статье описываются результаты анкетирования, которое проводилось в 2007-2008 гг. для оценки приверженности пациентов с остеоартритом (OА) коленных и тазобедренных суставов к различных методам лечения. Всего проанкетировано 54 пациента, наблюдающихся у 9 врачей общей практики г. Екатеринбурга и Свердловской области. Анализ демографических данных и индекса массы тела респондентов подтверждает значение ожирения как фактора риска 0А (средний ИМТ 32±6,8 кг/м2) и преимущественное развитие заболевания у лиц женского пола (88,8% респондентов). Обнаружена статистически достоверная связь между увеличением возраста респондентов и повышением частоты использования тепловых процедур (ДИ 0,07- 0,73), грязелечения и лечебных ванн (ДИ 0,07-0,96). Выявлено, что предпочитаемая частота использования большинства медицинских вмешательств — несколько раз в месяц или по потребности, при этом к ежедневному лечению приверженность низкая. Получены данные о высокой частоте использования НПВП как внутрь, так и местно, а также высокой приверженности к локальным средствам лечения в целом. К снижению веса и гимнастике пациенты продемонстрировали относительно низкую приверженность, при этом средства народной медицины и парафармацевтики пользуются высокой популярностью. Кроме того, в результате анкетирования выявлено значительное количество необоснованных рентгенографий коленных суставов (31,1%). В целом исследование продемонстрировало, что диагностика и лечение ОА в первичном звене далеки от оптимальных, что может быть связано с устаревшими клинико-организационными стандартами, недостаточным взаимодействием между врачами и пациентами, а также с трудностями в изменении поведенческих стереотипов и предпочтением пациентами более простых, дешевых и доступных методов лечения

Harmonic decomposition to describe the nonlinear evolution of stimulated Brillouin scattering

An efficient method to describe the nonlinear evolution of stimulated Brillouin scattering(SBS) in long scale-length plasmas is presented in the limit of a fluid description. The method is based on the decomposition of the various functions characterizing the plasma into their long- and short-wavelength components. It makes it possible to describe self-consistently the interplay between the plasmahydrodynamics,stimulated Brillouin scattering, and the generation of harmonics of the excited ion acoustic wave(IAW). This description is benchmarked numerically in one and two spatial dimensions [one dimensional (1D), two dimensional (2D)], by comparing the numerical results obtained along this method with those provided by a numerical code in which the decomposition into separate spatial scales is not made. The decomposition method proves to be very efficient in terms of computing time, especially in 2D, and very reliable, even in the extreme case of undamped ion acoustic waves. A novel picture of the SBS nonlinear behavior arises, in which the IAWharmonics generation gives rise to local defects appearing in the density and velocity hydrodynamics profiles. Consequently, SBS develops in various spatial domains which seem to be decorrelated one from each other, so that the backscattered Brillouin light is the sum of various backscatteredwaves generated in several independent spatial domains. It follows that the SBSreflectivity is chaotic in time and the resulting time-averaged value is significantly reduced as compared to the case when the IAWharmonics generation and flow modification are ignored. From the results of extensive numerical simulations carried out in 1D and 2D, we are able to infer the SBSreflectivity scaling law as a function of the plasma parameters and laser intensity, in the limit where the kinetic effects are negligible. It appears that this scaling law can be derived in the limit where the IAWharmonics generation is modeled simply by a nonlinear frequency shift

Critical Strain Region Evaluation of Self-Assembled Semiconductor Quantum Dots

A novel peak finding method to map the strain from high resolution transmission electron micrographs, known as the Peak Pairs method, has been applied to In(Ga) As/AlGaAs quantum dot (QD) samples, which present stacking faults emerging from the QD edges. Moreover, strain distribution has been simulated by the finite element method applying the elastic theory on a 3D QD model. The agreement existing between determined and simulated strain values reveals that these techniques are consistent enough to qualitatively characterize the strain distribution of nanostructured materials. The correct application of both methods allows the localization of critical strain zones in semiconductor QDs, predicting the nucleation of defects, and being a very useful tool for the design of semiconductor device

Роль витаминов-антиоксидантов в этиологии ревматоидного артрита

There is evidence that insufficient intake of antioxidants may increase the risk of autoimmune inflammatory diseases, including rheumatoid arthritis (RA). Also, lower plasma concentrations of antioxidant vitamins can be a sign of their heavy expenditure to suppress inflammatory processes in the preclinical stage of RA. This article provides an overview of modern studies that have assessed a relationship between the incidence of RA and serum levels or dietary intake of vitamins A, E, C and beta-carotene. Case-control studies have revealed that α-tocopherol and β-cryptoxanthin have a protective effect and their high plasma levels are associated with the decreased incidence of RA. An inverse relationship has been also found between the dietary intake of carotenoids and vitamin C and the risk of RA. At the same time, larger prospective cohort studies have failed to confirm the relationship between the levels of consumption of the major antioxidant vitamins and the risk of RA. The currently available data on the role of antioxidant vitamins in the development of RA remains controversial. Conceivably, sufficient intake of the vitamins has no self-protective activity against RA, but serves as a marker for a healthier lifestyle that lowers the risk of many diseases, including autoimmune disorders.По некоторым данным, недостаточное потребление антиоксидантов может повышать риск развития аутоиммунных воспалительных заболеваний, в том числе ревматоидного артрита (РА). Кроме того, пониженная концентрация витаминов-антиоксидантов в плазме может быть связана с их интенсивным расходованием на подавление воспалительных процессов в доклиническую стадию РА. В настоящей статье представлен обзор современных исследований, в которых оценивалась связь между заболеваемостью РА и сывороточным уровнем, или диетическим потреблением, витаминов А, Е, С и бета-каротина. В исследованиях случай-контроль установлено, что альфа-токоферол и бета-криптоксантин обладают защитным эффектом и их высокие концентрации в плазме ассоциированы со снижением заболеваемости РА. Также была показана обратно пропорциональная зависимость между потреблением каротиноидов и витамина С и риском развития РА. В то же время в более крупных проспективных когортных исследованиях взаимосвязь уровня потребления основных витаминов-антиоксидантов и риска возникновения РА не подтверждена. Имеющиеся данные о роли витаминов-антиоксидантов в развитии РА противоречивы. Возможно, достаточное потребление витаминов не оказывает самостоятельного защитного действия в отношении развития РА, но является маркером более здорового образа жизни, при котором уменьшается вероятность многих заболеваний, в том числе аутоиммунных

The seasonal cycle of the greenhouse gas balance of a continental tundra site in the Indigirka lowlands, NE Siberia

International audienceCarbon dioxide and methane fluxes were measured at a tundra site near Chokurdakh, in the lowlands of the Indigirka river in north-east Siberia. This site is one of the few stations on Russian tundra and it is different from most other tundra flux stations in its continentality. A suite of methods was applied to determine the fluxes of NEE, GPP, Reco and methane, including eddy covariance, chambers and leaf cuvettes. Net carbon dioxide fluxes were unusually high, compared with other tundra sites, with NEE=?92 g C m?2 yr?1, which is composed of an Reco=+141 g C m?2 yr?1 and GPP=?232 g C m?2 yr?1. This large carbon dioxide sink may be explained by the continental climate, that is reflected in low winter soil temperatures (?14°C), reducing the respiration rates, and short, relatively warm summers, stimulating high photosynthesis rates. Interannual variability in GPP was dominated by the frequency of light limitation (Rg ?2), whereas Reco depends most directly on soil temperature and time in the growing season, which serves as a proxy of the combined effects of active layer depth, leaf area index, soil moisture and substrate availability. The methane flux, in units of global warming potential, was +28 g C-CO2e m?2 yr?1, so that the greenhouse gas balance was ?64 g C-CO2e m?2 yr?1. Methane fluxes depended only slightly on soil temperature and were highly sensitive to hydrological conditions and vegetation composition

Presence of nanoplastics in rural and remote surface waters

It is now established that microplastics are a pervasive presence in aquatic and terrestrial ecosystems. The same is assumed to be true for nanoplastics but data are lacking due to technical difficulties associated with sample analysis. Here, we measured nanoplastics in waterbodies at two contrasting sites: remote Siberian Arctic tundra and a forest landscape in southern Sweden. Nanoplastics were detected in all sampled Swedish lakes (n = 7) and streams (n = 4) (mean concentration = 563 µg l−1) and four polymer types were identified (polyethylene, polyvinyl chloride (PVC), polypropylene, polyethylene terephthalate). In Siberia nanoplastics were detected in 7/12 sampled lakes, ponds and surface flooding, but only two polymer types were detected (PVC and polystyrene) and concentrations were lower (mean 51 µg l−1). Based on back-calculation of air mass trajectories and particle dispersion, we infer that nanoplastics arrive at both sites by aerial deposition from local and regional sources. Our results suggest that nanoplastics may be a near-ubiquitous presence even in remote ecosystems

Vertical-external-cavity surface-emitting lasers and quantum dot lasers

The use of cavity to manipulate photon emission of quantum dots (QDs) has been opening unprecedented opportunities for realizing quantum functional nanophotonic devices and also quantum information devices. In particular, in the field of semiconductor lasers, QDs were introduced as a superior alternative to quantum wells to suppress the temperature dependence of the threshold current in vertical-external-cavity surface-emitting lasers (VECSELs). In this work, a review of properties and development of semiconductor VECSEL devices and QD laser devices is given. Based on the features of VECSEL devices, the main emphasis is put on the recent development of technological approach on semiconductor QD VECSELs. Then, from the viewpoint of both single QD nanolaser and cavity quantum electrodynamics (QED), a single-QD-cavity system resulting from the strong coupling of QD cavity is presented. A difference of this review from the other existing works on semiconductor VECSEL devices is that we will cover both the fundamental aspects and technological approaches of QD VECSEL devices. And lastly, the presented review here has provided a deep insight into useful guideline for the development of QD VECSEL technology and future quantum functional nanophotonic devices and monolithic photonic integrated circuits (MPhICs).Comment: 21 pages, 4 figures. arXiv admin note: text overlap with arXiv:0904.369

Measurement of the Longitudinal Spin Transfer to Lambda and Anti-Lambda Hyperons in Polarised Muon DIS

The longitudinal polarisation transfer from muons to lambda and anti-lambda hyperons, D_LL, has been studied in deep inelastic scattering off an unpolarised isoscalar target at the COMPASS experiment at CERN. The spin transfers to lambda and anti-lambda produced in the current fragmentation region exhibit different behaviours as a function of x and xF . The measured x and xF dependences of D^lambda_LL are compatible with zero, while D^anti-lambda_LL tends to increase with xF, reaching values of 0.4 - 0.5. The resulting average values are D^lambda_LL = -0.012 +- 0.047 +- 0.024 and D^anti-lambda_LL = 0.249 +- 0.056 +- 0.049. These results are discussed in the frame of recent model calculations.Comment: 13 pages, 7 figure