Self consistent kinetic simulations of SPT and HEMP thrusters including the near-field plume region

The Particle-in-Cell (PIC) method was used to study two different ion thruster concepts - Stationary Plasma Thrusters (SPT) and High Efficiency Multistage Plasma Thrusters (HEMP-T), in particular the plasma properties in the discharge chamber due to the different magnetic field configurations. Special attention was paid to the simulation of plasma particle fluxes on the thrusters channel surfaces. In both cases, PIC proved itself as a powerful tool, delivering important insight into the basic physics of the different thruster concepts. The simulations demonstrated that the new HEMP thruster concept allows for a high thermal efficiency due to both minimal energy dissipation and high acceleration efficiency. In the HEMP thruster the plasma contact to the wall is limited only to very small areas of the magnetic field cusps, which results in much smaller ion energy flux to the thruster channel surface as compared to SPT. The erosion yields for dielectric discharge channel walls of SPT and HEMP thrusters were calculated with the binary collision code SDTrimSP. For SPT, an erosion rate on the level of 1 mm of sputtered material per hour was observed. For HEMP, thruster simulations have shown that there is no erosion inside the dielectric discharge channel.Comment: 14 pages, 11 figures This work was presented at 21st International Conference on Numerical Simulation of Plasmas (ICNSP'09

Swelling and mechanical properties of alginate hydrogels with respect to promotion of neural growth

Soft alginate hydrogels support robust neurite outgrowth, but their rapid disintegration in solutions of high ionic strength restricts them from long-term in vivo applications. Aiming to enhance the mechanical stability of soft alginate hydrogels, we investigated how changes in pH and ionic strength during gelation influence the swelling, stiffness, and disintegration of a three-dimensional (3D) alginate matrix and its ability to support neurite outgrowth. Hydrogels were generated from dry alginate layers through ionic crosslinks with Ca(2+) (<=10 mM) in solutions of low or high ionic strength and at pH 5.5 or 7.4. High- and low-viscosity alginates with different molecular compositions demonstrated pH and ionic strength-independent increases in hydrogel volume with decreases in Ca(2+) concentrations from 10 to 2 mM. Only soft hydrogels that were synthesized in the presence of 150 mM of NaCl (Ca-alginateNaCl) displayed long-term volume stability in buffered physiological saline, whereas analogous hydrogels generated in NaCl-free conditions (Ca-alginate) collapsed. The stiffnesses of Ca-alginateNaCl hydrogels elevated from 0.01 to 19 kPa as the Ca(2+)-concentration was raised from 2 to 10 mM; however, only Ca-alginateNaCl hydrogels with an elastic modulus <=1.5 kPa that were generated with <=4 mM of Ca(2+) supported robust neurite outgrowth in primary neuronal cultures. In conclusion, soft Ca-alginateNaCl hydrogels combine mechanical stability in solutions of high ionic strength with the ability to support neural growth and could be useful as 3D implants for neural regeneration in vivo

Buckling of Cylindrical Shells of Variable Thickness, Loaded by External Uniform Pressure

From the mathematical standpoint one has a partial&nbsp; differential equation with variable coefficients. Perturbation procedure gives the possibilityfor an analytical solution of this eigenvalue problem. Self-adjoint equations and Padé approximants are used for improving the obtained results

The subpopulation of microglia sensitive to neurotransmitters/neurohormones is modulated by stimulation with LPS, interferon-γ, and IL-4

Recently, neurotransmitters/neurohormones have been identified as factors controlling the function of microglia, the immune competent cells of the central nervous system. In this study, we compared the responsiveness of microglia to neurotransmitters/neurohormones. We freshly isolated microglia from healthy adult C57Bl/6 mice and found that only a small fraction (1-20%) responded to the application of endothelin, histamine, substance P, serotonin, galanin, somatostatin, angiotensin II, vasopressin, neurotensin, dopamine, or nicotine. In cultured microglia from neonatal and adult mice, a similarly small population of cells responded to these neurotransmitters/neurohormones. To induce a proinflammatory phenotype, we applied lipopolysaccaride (LPS) or interferon-gamma (IFN-{gamma}) to the cultures for 24 h. Several of the responding populations increased; however, there was no uniform pattern when comparing adult with neonatal microglia or LPS with IFN-{gamma} treatment. IL-4 as an anti-inflammatory substance increased the histamine-, substance P-, and somatostatin-sensitive populations only in microglia from adult, but not in neonatal cells. We also found that the expression of different receptors was not strongly correlated, indicating that there are many different populations of microglia with a distinct set of receptors. Our results demonstrate that microglial cells are a heterogeneous population with respect to their sensitivity to neurotransmitters/neurohormones and that they are more responsive in defined activation states

МЕДИКО-ЕКСПЕРТНІ КРИТЕРІЇ ОБМЕЖЕННЯ ЖИТТЄДІЯЛЬНОСТІ ПРИ НАСЛІДКАХ ПЕРЕНЕСЕНОГО ІНСУЛЬТУ

Purpose: to adapt “International classification of functioning, limitation of vital functions and health” (ICFH) focusing for the inspection of patients with the consequences of the prior stroke. Materials and Methods. In the angyoneurology separation of the Brovary Central Hospital a study is undertaken 110 patients with theconsequences of stroke, capable of working age. All patients passed a standard clinical neurological inspectionand testing after ICFH.Results: factors are certain, the criteria of limitation of vital functions are worked out in the main spheres of life. It is well- proven that adaptation of ICFH allows to apply it at expert diagnostics, to formulation of correct  clinical, functional diagnosis, gives an opportunity to estimate potential and efficiency of rehabilitation measures for patients with the consequences of the prior stroke.Conclusions: 1. Application of ICFH gives an opportunity bjectively to estimate the state of patients, rehabilitation potential and efficiency of realization of rehabilitation measures for patients with the consequences of the prior stroke.2. The use of the criteria of limitation of vital functions worked out by us will allow to improve quality medico-social examination of patients that suffered a stroke, and to optimize further researches new going near the rehabilitation of this category of patients and adaptation in society.Мета: адаптувати Міжнародну класифікацію функціонування, обмеження життєдіяльності та здоров’я (МКФ) для використання при обстеженні хворих із наслідками перенесеного інсульту.Матеріали і методи. У ангіоневрологічному відділенні Броварської центральної лікарні проведено дослідження 110 хворих працездатного віку із наслідками перенесеного інсульту. Всі хворі пройшли стандартне клінічне неврологічне обстеження і тестування за МКФ.Результати. Визначено чинники, розроблено критерії обмеження життєдіяльності у головних сферах життя. Доведено, що адаптація МКФ дозволяє застосовувати її при експертній діагностиці, формулюванні правильного клінічного, функціонального діагнозу, дає можливість оцінити потенціал і ефективність реабілітаційних заходів у хворих із наслідками перенесеного інсульту.Висновки. 1. Застосування МКФ дає змогу об’єктивно оцінити стан хворих, реабілітаційний потенціал і ефективність проведення реабілітаційних заходів у хворих із наслідками перенесеного інсульту.2. Використання розроблених нами критеріїв обмеження життєдіяльності дозволить підвищити якість медико-соціальної експертизи хворих, які перенесли інсульт, а подальші дослідження оптимізувати нові підходи до реабілітації цієї категорії хворих та адаптації в суспільстві

Spontaneous Ca(2+) transients in mouse microglia

Microglia are the resident immune cells in the central nervous system and many of their physiological functions are known to be linked to intracellular calcium (Ca2+) signaling. Here we show that isolated and purified mouse microglia-either freshly or cultured-display spontaneous and transient Ca2+ elevations lasting for around ten to twenty seconds and occurring at frequencies of around five to ten events per hour and cell. The events were absent after depletion of internal Ca2+ stores, by phospholipase C (PLC) inhibition or blockade of inositol-1,4,5-trisphosphate receptors (IP3Rs), but not by removal of extracellular Ca2+, indicating that Ca2+ is released from endoplasmic reticulum intracellular stores. We furthermore provide evidence that autocrine ATP release and subsequent activation of purinergic P2Y receptors is not the trigger for these events. Spontaneous Ca2+ transients did also occur after stimulation with Lipopolysaccharide (LPS) and in glioma-associated microglia, but their kinetics differed from control conditions. We hypothesize that spontaneous Ca2+ transients reflect aspects of cellular homeostasis that are linked to regular and patho-physiological functions of microglia

Satellite microglia display spontaneous electrical activity uncorrelated with activity of the attached neuron

Microglia are innate immune cells of the brain. We have studied a subpopulation of microglia, called satellite microglia. This cell type is defined by a close morphological soma-to-soma association with a neuron, indicative of a direct functional interaction. Indeed, ultrastructural analysis revealed closely attached plasma membranes of satellite microglia and neurons. However, we found no apparent morphological specializations of the contact and biocytin injection into satellite microglia showed no dye-coupling with the apposed neuron or any other cell. Likewise, evoked local field potentials or action potentials and postsynaptic potentials of the associated neuron did not lead to any transmembrane currents or non-capacitive changes in the membrane potential of the satellite microglia in the cortex and hippocampus. Both satellite and non-satellite microglia, however, showed spontaneous transient membrane depolarizations which were not correlated with neuronal activity. These events could be divided into fast and slow rising depolarisations, which exhibited different characteristics in satellite and non-satellite microglia. Fast and slow rising potentials differed with regard to voltage dependence. The frequency of these events was not affected by application of TTX, but fast rising event frequency decreased after application of GABA. We conclude that microglial cells show spontaneous electrical activity uncorrelated with the activity of adjacent neurons

Radio-frequency discharges in Oxygen. Part 1: Modeling

In this series of three papers we present results from a combined experimental and theoretical effort to quantitatively describe capacitively coupled radio-frequency discharges in oxygen. The particle-in-cell Monte-Carlo model on which the theoretical description is based will be described in the present paper. It treats space charge fields and transport processes on an equal footing with the most important plasma-chemical reactions. For given external voltage and pressure, the model determines the electric potential within the discharge and the distribution functions for electrons, negatively charged atomic oxygen, and positively charged molecular oxygen. Previously used scattering and reaction cross section data are critically assessed and in some cases modified. To validate our model, we compare the densities in the bulk of the discharge with experimental data and find good agreement, indicating that essential aspects of an oxygen discharge are captured.Comment: 11 pages, 10 figure

ПРОБЛЕМНО–ОРІЄНТОВАНА ОСВІТА

The article for the purpose of effective integration into the European educational space, adduces the problems of modern education inUkraine. It is noted that the effective professional formation of a student of Medical University is possible into accouat the characterogical, etnocultural features of personality and from the development of the country.В статті, з метою ефективної інтеграції в Європейський освітній простір,  окреслені проблеми сучасної освіти в Україні. Визначено, що ефективне професійне формування студента медичного університету можливе з врахуванням характерологічних, етнокультуральних особливостей особистості та є невідривним від розвитку країни