Rapid directional alignment of velocity and magnetic field in magnetohydrodynamic turbulence

We show that local directional alignment of the velocity and magnetic field fluctuations occurs rapidly in magnetohydrodynamics for a variety of parameters. This is observed both in direct numerical simulations and in solar wind data. The phenomenon is due to an alignment between the magnetic field and either pressure gradients or shear-associated kinetic energy gradients. A similar alignment, of velocity and vorticity, occurs in the Navier Stokes fluid case. This may be the most rapid and robust relaxation process in turbulent flows, and leads to a local weakening of the nonlinear terms in the small scale vorticity and current structures where alignment takes place.Comment: 4 pages, 6 figure

Polymorphism of gene of IL-8 cytokine in acute pancreatitis complicated with peritonitis

This study has assessed the possible association of IL-8 (-251А/Т) polymorphism with clinical course of pancreatogenic peritonitis and suggests that the identification of genetic polymorphism of IL-8 (-251A/T) may be informative and serve as an additional criterion to predict both the clinical course and outcome of pancreatogenic peritonitis.Te studium zostało przeprowadzone w celu określenia możliwego związku miedzy genetycznym polimorfem cytokiny IL-8 (-251А/Т), a jego wpływu na warianty klinicznego przebiegu ostrego zapalenia trzustki, skomplikowanego zapaleniem otrzewnej i może dostarczać informacyji i służyć jak dodatkowe kryterium prognozowania

Деякі аспекти підготовки фахівців з радіотехніки в сучасних умовах

The problem of experts preparing in radio engineering specialists' in modem environment has been discussed. The education plan is analysed and the improvement ways of experts preparing is proposed.Обсуждаются проблемы подготовки специалистов направления радиотехники в современных условиях. Анализируется содержание учебного плана, предлагаются пути улучшения подготовки специалистов.Обговорюються проблеми підготовки фахівців напряму радіотехніка в сучасних умовах. Аналізується наведений навчальний план, пропонуються шляхи покращення підготовки фахівців

Magnetic Reconnection As An Element Of Turbulence

In this work, recent advances on the study of reconnection in turbulence are reviewed. Using direct numerical simulations of decaying incompressible two-dimensional magnetohydrodynamics (MHD), it was found that in fully developed turbulence complex processes of reconnection locally occur (Servidio et al., 2009, 2010a). In this complex scenario, reconnection is spontaneous but locally driven by the fields, with the boundary conditions provided by the turbulence. Matching classical turbulence analysis with a generalized Sweet-Parker theory, the statistical features of these multiple-reconnection events have been identified. A discussion on the accuracy of our algorithms is provided, highlighting the necessity of adequate spatial resolution. Applications to the study of solar wind discontinuities are reviewed, comparing simulations to spacecraft observations. New results are shown, studying the time evolution of these local reconnection events. A preliminary study on the comparison between MHD and Hall MHD is reported. Our new approach to the study of reconnection as an element of turbulence has broad applications to space plasmas, shedding a new light on the study of magnetic reconnection in nature

Spatio-temporal behavior of magnetohydrodynamic fluctuations with cross-helicity and background magnetic field

We study the spatiotemporal behavior of the Elsässer variables describing magnetic and velocity field fluctuations, using direct numerical simulations of three-dimensional magnetohydrodynamic turbulence. We consider cases with relatively small, intermediate, and large values of a mean background magnetic field and with null, small, and high cross-helicity (correlations between the velocity and the magnetic field). Wavenumber-dependent time correlation functions are computed for the different simulations. From these correlation functions, the decorrelation time is computed and compared with different theoretical characteristic times: the local nonlinear time, the random-sweeping time, and the Alfvénic time. It is found that decorrelation times are dominated by sweeping effects for low values of the mean magnetic field and for low values of the cross-helicity, while for large values of the background field or of the cross-helicity and for wave vectors sufficiently aligned with the guide field, decorrelation times are controlled by Alfvénic effects. Finally, we observe counterpropagation of Alfvénic fluctuations due to reflections produced by inhomogeneities in the total magnetic field. This effect becomes more prominent in flows with large cross-helicity, strongly modifying the propagation of waves in turbulent magnetohydrodynamic flows.Fil: Lugones, Rodrigo. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Dmitruk, Pablo Ariel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Mininni, Pablo Daniel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física de Buenos Aires; ArgentinaFil: Pouquet, A.. University of Colorado; Estados UnidosFil: Matthaeus, W. H.. University of Colorado; Estados Unido

Coronal heating distribution due to low-frequency wave-driven turbulence

The heating of the lower solar corona is examined using numerical simulations and theoretical models of magnetohydrodynamic turbulence in open magnetic regions. A turbulent energy cascade to small length scales perpendicular to the mean magnetic field can be sustained by driving with low-frequency Alfven waves reflected from mean density and magnetic field gradients. This mechanism deposits energy efficiently in the lower corona, and we show that the spatial distribution of the heating is determined by the mean density through the Alfven speed profile. This provides a robust heating mechanism that can explain observed high coronal temperatures and accounts for the significant heating (per unit volume) distribution below two solar radius needed in models of the origin of the solar wind. The obtained heating per unit mass on the other hand is much more extended indicating that the heating on a per particle basis persists throughout all the lower coronal region considered here.Comment: 19 pages, 5 figures. Accepted for publication in Ap

Features of cytokine spectrum in chronic urticarial

Urticaria is a serious medical and social problem due to its high prevalence, lack of unified approaches to diagnosis and treatment, with high financial costs for therapy and rehabilitation. Long-term recurrent course of the disease, resistance to traditional methods of therapy lead to a significant decrease in the quality of life of patients with chronic urticaria. Itching accompanying this disease leads to deterioration in the patient’s general well-being, frequent sleep disturbances and, as a result, significant decrease in working capacity. Up to the present moment, etiopathogenesis of urticaria is a complex challenge due to the multivector nature of cytokine response, interference of protides of the complement system, patterns of kininbradykinin interference, peculiar expression of the immune response. The problem of current population is lipotrophy – chronic, heterogeneous, cytokine mediating, progressive inflammatory disease attributed by abnormal accumulation of excessive adipose tissue. Adipose tissue, being a sporadic organ of endocrine system secretes multiple hormone-like substances, mediators, cytokines and chemokines which have been given a common name, i.e., adipokines or adipocytokines. True signs of destructive parenchymal changes of liver in the form of increasing bilirubin and AST, decreasing level of vitamin D in patients with chronic recurrent urticarial in presence of obesity have been revealed during the study performed. The action of cytokines, as mediators of intercellular interaction is closely related to the physiological and pathophysiological responses of the body with modulation of both local and systemic defense mechanisms. It is assumed that the cytokine status of patients with chronic urticaria is dominated by cytokines that increase allergic inflammation of the skin. Analysis of 12 T regulatory biomarker concentrations revealed increased concentrations of IL-10, IL-19, IL-20, IL-27, IL-35, IFNλ2 and IFNλ1 in blood serum of patients with chronic urticaria. It was found that in the group of patients with chronic urticaria and increased body mass index (BMI), the level of all investigated T regulatory cytokines is lower than in the patients with normal BMI, except for IL-10. Decreased levels of biologically active IFN I (α/β) and, especially, IFN II (γ) types of blood leukocytes in patients with chronic urticaria were revealed. The levels of 12 Treg cytokines were determined in blood serum of patients with chronic urticaria, showing trend for imbalance of Treg cytokines: IL-10, IL-19, IL-20, IL-27, IL-35, IFNλ2 and IFNλ1