Poloidal inhomogeneity of the particle fluctuation induced fluxes near of the LCFS at lower hybrid heating and improved confinement transition at the FT-2 tokamak

This paper deals with the new spectral and microturbulence experimental data and their analysis, which show, that the radial electric field Er generated at the LH heating (LHH) in the FT-2 is high enough to form the transport barriers. The ETB is formed when LHH is switched off. The radial fluctuation-induced EB drift flux densities near LCFS in SOL are measured at two different poloidal angles. For this purpose two Langmuir probes located at low and high field sides of the torus are used. Registration of the poloidal and radial components of the electric field and density fluctuations at the same time during one discharge permits to measure the poloidal asymmetry of the transport reduction mechanism of the radial and poloidal particle fluxes in the SOL. The absolute E(~) fluctuation levels show dependence on the sign of Er shear. The modification of the microscale turbulence by the poloidal Er x B rotation shear EB at the L - H transition near LCFS is also studied by X-mode fluctuation Reflectometry. The new data were obtained by spatial spectroscopic technique.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

Structural and transport properties of GaAs/delta<Mn>/GaAs/InxGa1-xAs/GaAs quantum wells

We report results of investigations of structural and transport properties of GaAs/Ga(1-x)In(x)As/GaAs quantum wells (QWs) having a 0.5-1.8 ML thick Mn layer, separated from the QW by a 3 nm thick spacer. The structure has hole mobility of about 2000 cm2/(V*s) being by several orders of magnitude higher than in known ferromagnetic two-dimensional structures. The analysis of the electro-physical properties of these systems is based on detailed study of their structure by means of high-resolution X-ray diffractometry and glancing-incidence reflection, which allow us to restore the depth profiles of structural characteristics of the QWs and thin Mn containing layers. These investigations show absence of Mn atoms inside the QWs. The quality of the structures was also characterized by photoluminescence spectra from the QWs. Transport properties reveal features inherent to ferromagnetic systems: a specific maximum in the temperature dependence of the resistance and the anomalous Hall effect (AHE) observed in samples with both "metallic" and activated types of conductivity up to ~100 K. AHE is most pronounced in the temperature range where the resistance maximum is observed, and decreases with decreasing temperature. The results are discussed in terms of interaction of 2D-holes and magnetic Mn ions in presence of large-scale potential fluctuations related to random distribution of Mn atoms. The AHE values are compared with calculations taking into account its "intrinsic" mechanism in ferromagnetic systems.Comment: 15 pages, 9 figure

Role of turbulence and electric fields in the formation of transport barriers and the establishment of improved confinement in tokamak plasmas through inter-machine comparison

Over the past decade new regimes of tokamak operation have been identified, whereby electrostatic and magnetic turbulence responsible for anomalous transport, can be externally suppressed, leading to improved confinement. Although turbulence measurements have been performed on many confinement devices, the insight gained from these experiments is relatively limited. To make further progress in the understanding of plasma turbulence in relation to improved confinement and transport barriers, an extensive experimental and theoretical research programme should be undertaken. The present INTAS project investigates the correlations between on the one hand the occurrence of transport barriers and improved confinement in the tokamaks TEXTOR & T-10 and Tore Supra as well as on the smaller-scale tokamaks FT-2, TUMAN-3M and CASTOR, and on the other hand electric fields, modified magnetic shear and electrostatic and magnetic turbulence using advanced diagnostics with high spatial and temporal resolution. This is done in a strongly coordinated way and exploiting the complementarity of TEXTOR and T-10 and the backup potential of the other tokamaks, which together have all the relevant experimental tools and theoretical expertise. Advanced theoretical models and numerical simulations are used to check the experimental results.За останні десять років було отримано нові режими роботи токамаків, у яких електростатична і магнітна турбулентність, відповідальна за аномальний перенос, могла заглушатися шляхом зовнішнього впливу, і тим самим досягалося поліпшене утримання. Незважаючи на те, що дослідження турбулентності проводилися на багатьох установках, розуміння цих процесів залишається досить обмеженим. Для досягнення подальшого прогресу в розумінні плазмової турбулентності з погляду поліпшеного утримання і транспортних бар'єрів необхідні інтенсивні експериментальні і теоретичні дослідження. Проект INTAS спрямовано на з'ясування кореляції між виникненням транспортних бар'єрів і поліпшеного утримання в токамаках TEXTOR, Т-10 і Tore Supra, а також у токамаках малих розмірів ФТ-2, ТУМАН-3М и CASTOR, з одного боку, і електричними полями, модифікованим магнітним широм і електростатичною і магнітною турбулентністю, з іншого боку, з використанням передових діагностичних засобів з високим просторовим і тимчасовим розділенням. Дослідження проводяться з високим ступенем координації робіт і використанням взаємодоповнюваності установок TEXTOR і Т-10, і можливостей інших токамаків, що в сукупності забезпечить необхідну експериментальну і теоретичну перевірку. Для перевірки експериментальних результатів буде використано нові теоретичні моделі і чисельне моделювання.В последние десять лет были получены новые режимы работы токамаков, в которых электростатическая и магнитная турбулентность, ответственная за аномальный перенос, могла подавляться путём внешнего воздействия, и тем самым достигалось улучшенное удержание. Несмотря на то, что исследования турбулентности проводились на многих установках, понимание этих процессов остаётся весьма ограниченным. Для достижения дальнейшего прогресса в понимании плазменной турбулентности с точки зрения улучшенного удержания и транспортных барьеров необходимы интенсивные экспериментальные и теоретические исследования. Проект INTAS направлен на выяснение корреляции между возникновением транспортных барьеров и улучшенного удержания в токамаках TEXTOR, Т-10 и Tore Supra, а также в токамаках малых размеров ФТ-2, ТУМАН-3М и CASTOR, с одной стороны, и электрическими полями, модифицированным магнитным широм и электростатической и магнитной турбулентностью, с другой стороны, с использованием передовых диагностических средств с высоким пространственным и временным разрешением. Исследования проводятся с высокой степенью координации работ и использованием взаимодополняемости установок TEXTOR и Т-10, и возможностей других токамаков, что в совокупности обеспечит необходимую экспериментальную и теоретическую проверку. Для проверки экспериментальных результатов будут использованы новые теоретические модели и численное моделирование

Structural and functional changes of the heart in patients with chronic ischemic heart failure, associated with renal dysfunction

Kidney disease is a frequent complication of congestive heart failure (CHF) and may contribute to the progression of ventricular dysfunction. Regardless of the degree of heart failure, chronic kidney disease (CKD) increases the risk of death and cardiac decompensation. Left ventricular hypertrophy (LVH) is a known parameter of cardiac remodelling and has a higher prevalence and incidence among people with impaired kidney function. LVH is an early subclinical marker of cardiovascular disease and heart failure risk, and is probably an intermediary step in the pathway leading from kidney dysfunction to heart failure and its complications. The effects of CKD on other left ventricular and myocardial parameters, however, have been less characterized. The aim of the study was to examine the structural and functional changes, geometric remodeling of the heart in patients with ischemic chronic heart failure, being hospitalized, according to the presence of renal dysfunction. Materials and methods. The study involved 333 patients with ischemic CHF (277 men and 56 women, mean age 59,3±9,4 years). The functional class of heart failure was assessed on the recommendations of the New York Heart Association (NYHA). The etiology of heart failure in 288 (86.5%) patients had a combination of coronary artery disease and essential hypertension, in 45 (13.5%) – only CAD. 1 FC of heart failure was diagnosed in 9 (2.7%) patients, 2 FC - in 106 (31.8%), 3 FC - in 199 (59.8%) and 4 FC - 19 (5.7%) patients. Diabetes was in 61 (18.3%), myocardial infarction history was in 240 (72.1%) patients. Depending on the glomerular filtration rate, patients were divided into 3 groups: 72 with normal GFR (>90 ml/min/1.73m2), 218 with a slight decrease in GFR (60-90 ml/min/1.73m2) and 43 with moderate reduced GFR (<60 ml/min/1.73m2). Echocardiography was performed using the General Electric VIVID 3 system (General Electric Healthcare, USA) with the 2.5–3.5 MHz transducer and Doppler technique. Descriptive statistics are presented as mean±standard deviation for continuous variables and as percentages for categorical variables. Depending on the distribution of the analyzed parameters used unpaired Student's t-test or U-Mann-Whitney test. Comparisons among all groups for baseline clinical variables were performed with the Pearson χ2 or Fisher exact test for categorical variables. Differences considered reliable for values of p<0,05. Results. In patients with ischemic CHF as far as reduction of GFR, an increase in left atrial diameter (p=0.006), end-diastolic size (p=0.03), end-systolic size (p=0.003) end-diastolic (p=0.03) and end-systolic volumes (p=0.02). Analysis of ejection fraction showed a significant reduction in the progression of renal dysfunction: from 55,1±14,5% in GFR over 90 ml/min/1,73m2 to 46,3±14,6% with a GFR less than 60 ml/min/1.73 m2. LV hypertrophy was registered in 63 (87.5%) with normal renal function, in 202 (92.7%) with mild dysfunction and in 42 (97.7%) patients with moderate renal dysfunction. In the analysis of LV remodeling in patients with heart failure and normal renal function revealed the prevalence of concentric hypertrophy - in 45.8%. In mild decrease GFR stored value for concentric hypertrophy in 50% of cases. However, at lower eGFR less than 60 ml/min/1,73m2 dominated eccentric hypertrophy - in 55.8%, concentric hypertrophy in 41.9% and no patient with normal geometry. After analyzing the distribution of patients by type of violation diastolic function in patients with ischemic CHF, depending on the level of GFR, we can conclude that in normal renal function in 48.6% reported pseudonormal type, 36.1% - a abnormal of relaxation, 4.2% - restrictive type. In patients with mild to moderate decrease in GFR revealed a gradual deterioration in diastolic function as increase the proportion of more serious disorders: pseudonormal (56.9% and 60.5%, respectively) and restrictive type (3.7% and 9.3%, respectively). Conclusion. In patients with ischemic CHF decrease in GFR accompanied by structural adjustment in the form of an increase in the diameter of the left atrium, left ventricle, both in diastole and systole. The presence of renal dysfunction is associated with increased left ventricular myocardium index, the development of maladaptive remodeling of the left ventricle, as increase in patients with eccentric hypertrophy and diastolic function deterioration dominated pseudonormal and restrictive type. Thus, the progressive decrease GFR in patients with ischemic chronic heart failure accompanied geometric and hemodynamic transformation that leads to severe diastolic dysfunction

Age features of myocardial remodeling in men with ischemic chronic heart failure and renal dysfunction

In recent years, medicine has faced the problem of "dual epidemic" of heart and kidney failure. Regardless of the degree of heart failure, chronic kidney disease increases the risk of death and cardiac decompensation. Left ventricular hypertrophy (LVH) is a well known option of cardiac remodeling and it has higher prevalence among people with impaired renal function. Types of myocardial remodeling identify mortality risk of patients with cardiovascular complications. We know that gender and age are important risk factors for cardiovascular disease. However, in most studies structural remodeling of the myocardium was analyzed without sex and age characteristics. The aim of research is to study the age features of the formation of different types of myocardial remodeling in men with ischemic chronic heart failure and renal dysfunction. Materials and methods. To investigate the age characteristics of cardiac remodeling in men with ischemic chronic heart failure and renal dysfunction structural and functional remodeling of left ventricular myocardium was studied in 277 men (mean age 58,1±9,3 years) using Doppler echocardiography. Depending on the glomerular filtration rate, patients were divided into 3 groups: 58 with normal GFR (>90 ml/min/1.73m2), 182 with a slight decrease in GFR (60-90 ml/min/1.73m2) and 37 with moderately reduced GFR (<60 ml/min/1.73m2). Echocardiography was performed using the General Electric VIVID 3 system (General Electric Healthcare, USA) with the 2.5–3.5 MHz transducer and Doppler technique. Descriptive statistics are presented as mean±standard deviation for continuous variables and as percentages for categorical variables. Depending on the distribution of the analyzed parameters unpaired Student's t-test or U-Mann-Whitney test were used. Comparisons among all groups for baseline clinical variables were performed with the Pearson χ2 or Fisher exact test for categorical variables. Differences were considered reliable for values of p<0,05. Results. Based on the results of our study in 58 (20.9%) men renal dysfunction was not found, in 182 (65.8%) slight decrease and in 37 (13.3%) moderate reduction of renal function were found. To determine the effect of age on remodeling, we divided all the patients into two age groups: 60 years (middle age) - 166 (59.9%) and men older than 60 years (old age) - 111 (40.1%) people. When comparing the groups of middle-aged and elderly it was found that normal renal function was in 45 (27.1%) and 13 (11.7%) persons, respectively (χ2=11,2; p=0.0008), light kidney dysfunction was in 108 (65.1%) and 74 (66.7%) persons, respectively (χ2=0,8; p=0.78), moderate dysfunction was in 13 (7.8%) and 24 (21.6%) people, respectively (χ2=10,9; p=0.0009). In analyzing the types of LV remodeling in patients with heart failure and mild decrease in GFR normal geometry (9.3% vs. 2,7%; χ2=3,07; p=0.08), concentric remodeling (2.8% vs. 5,4%; χ2=0,82; p=0.37), concentric hypertrophy (44.4% vs. 40,5%; χ2=0,27; p=0.6), eccentric hypertrophy (43.5% vs. 51,4%; χ2=10,8; p=0.29) were revealed. However, at lower eGFR less than 60ml/min/1,73m2 in single patients normal geometry and concentric remodeling were revealed, concentric hypertrophy (23.1% vs. 50%; χ2=2,54; p=0.11), eccentric hypertrophy (76.9% vs. 50%; χ2=2,54; p=0.11). Thus, their data are consistent with the other studies, where the change in LV geometry in patients with chronic heart failure with progressive decline in renal function was revealed in favor of decrease of patients with the normal type of geometry, concentric remodeling and increase of patients with eccentric as one of the most unfavorable type of remodeling. Conclusion. In men with ischemic chronic heart failure in middle age in 7.8% and in old age in 21.6% of cases a moderate decrease in renal function is found. In men with ischemic chronic heart failure, regardless of age eccentric and concentric remodeling of the left ventricle occur equally often, in moderate decrease in renal function in middle age category concentric LV hypertrophy dominates and in elderly men eccentric and concentric hypertrophy are found equally common. Perspective is considered to take into account gender-age features of myocardial remodeling with a view to the appointment of a differentiated approach in the treatment of patients with ischemic chronic heart failure and renal dysfunction