Scaling law for the heating of solar coronal loops

We report preliminary results from a series of numerical simulations of the reduced magnetohydrodynamic equations, used to describe the dynamics of magnetic loops in active regions of the solar corona. A stationary velocity field is applied at the photospheric boundaries to imitate the driving action of granule motions. A turbulent stationary regime is reached, characterized by a broadband power spectrum $E_k\simeq k^{-3/2}$ and heating rate levels compatible with the heating requirements of active region loops. A dimensional analysis of the equations indicates that their solutions are determined by two dimensionless parameters: the Reynolds number and the ratio between the Alfven time and the photospheric turnover time. From a series of simulations for different values of this ratio, we determine how the heating rate scales with the physical parameters of the problem, which might be useful for an observational test of this model.Comment: 12 pages, 4 figures. Astrophysical Journal Letters (in press

Energy spectrum of turbulent fluctuations in boundary driven reduced magnetohydrodynamics

The nonlinear dynamics of a bundle of magnetic flux ropes driven by stationary fluid motions at their endpoints is studied, by performing numerical simulations of the magnetohydrodynamic (MHD) equations. The development of MHD turbulence is shown, where the system reaches a state that is characterized by the ratio between the Alfven time (the time for incompressible MHD waves to travel along the field lines) and the convective time scale of the driving motions. This ratio of time scales determines the energy spectra and the relaxation toward different regimes ranging from weak to strong turbulence. A connection is made with phenomenological theories for the energy spectra in MHD turbulence.Comment: Published in Physics of Plasma

Local plasmons contribution into photocurrent of Au/GaAs surface barrier structure with Au nanoparticles on interface

Au/SiO₂ core-shell nanoparticles have been used to increase the photocurrent in the surface barrier structure Au/GaAs. The method for theoretical calculation of interaction between light and the system of ordered nanoparticles placed on the surface barrier structures has been proposed. Local plasmons excited in the nanoparticles produce additional carriers due to scattering, prolonged interaction with semiconductor and enhanced evanescent electromagnetic field, thus they increase the photocurrent

Стратегия с замыканием в задаче оптимального гарантированного управления линейной системой

This paper deals with an optimal control problem for a linear discrete system subject to unknown bounded disturbances with the control goal being to steer the system with guarantees to a given target set while minimizing a given cost function. We define an optimal control strategy with one correction time instant, meaning taking into account information about one future state of the object, and propose an efficient numerical method for constructing it.Рассматривается задача оптимального управления линейной дискретной системой с неизвестными ограниченными возмущениями, которую требуется за конечное время перевести с гарантией на терминальное множество, обеспечивая при этом минимум гарантированного значения заданного критерия качества. Определяется оптимальная стратегия управления с замыканием, где под замыканием понимается учет информации об одном будущем состоянии объекта; предлагается эффективный алгоритм ее построения

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

Turbulence in the Solar Atmosphere: Manifestations and Diagnostics via Solar Image Processing

Intermittent magnetohydrodynamical turbulence is most likely at work in the magnetized solar atmosphere. As a result, an array of scaling and multi-scaling image-processing techniques can be used to measure the expected self-organization of solar magnetic fields. While these techniques advance our understanding of the physical system at work, it is unclear whether they can be used to predict solar eruptions, thus obtaining a practical significance for space weather. We address part of this problem by focusing on solar active regions and by investigating the usefulness of scaling and multi-scaling image-processing techniques in solar flare prediction. Since solar flares exhibit spatial and temporal intermittency, we suggest that they are the products of instabilities subject to a critical threshold in a turbulent magnetic configuration. The identification of this threshold in scaling and multi-scaling spectra would then contribute meaningfully to the prediction of solar flares. We find that the fractal dimension of solar magnetic fields and their multi-fractal spectrum of generalized correlation dimensions do not have significant predictive ability. The respective multi-fractal structure functions and their inertial-range scaling exponents, however, probably provide some statistical distinguishing features between flaring and non-flaring active regions. More importantly, the temporal evolution of the above scaling exponents in flaring active regions probably shows a distinct behavior starting a few hours prior to a flare and therefore this temporal behavior may be practically useful in flare prediction. The results of this study need to be validated by more comprehensive works over a large number of solar active regions.Comment: 26 pages, 7 figure

Адсорбционная активность сырья водно-болотных растений Западной Сибири

In order to find effective sorbents of herbal origin, we’ve studied adsorption properties of aerial dry raw materials of 31 marsh-water, medical perspective, plant species. It was found that 8 of those 31 exercises adsorption activity (Shpagnum species).С целью поиска эффективных сорбентов растительного происхождения изучены адсорбционные свойства сухого сырья 31 вида широко распространенных в Западной Сибири водно-болотных растений. Для 8 из них установлены выраженные адсорбционные свойства (мхи рода сфагнум), что позволяет отнести их к числу перспективных видов для получения эффективных сорбентов

КОЛИЧЕСТВЕННАЯ ОЦЕНКА НЕРВНО-МЫШЕЧНЫХ НАРУШЕНИЙ НА ОСНОВЕ ТЕКСТУРНОГО АНАЛИЗА ИЗОБРАЖЕНИЙ МАГНИТНО-РЕЗОНАНСНОЙ ТОМОГРАФИИ

Results on development of the basic concept of the medical image analysis methodology are presented. The techniques used in the research are based on adaptation and utilization of the gene-ralized image features for quantitative interpretation of muscles on nuclear magnetic resonance im-ages.Предлагаются результаты исследований по использованию базовой концепции методики ана-лиза медицинских изображений посредством адаптации универсальных дескрипторов изображений и их использования для количественной интерпретации областей мышц на изображениях магнитно-резонансной томографии