Stable multiple-charged localized optical vortices in cubic-quintic nonlinear media

The stability of two-dimensional bright vortex solitons in a media with focusing cubic and defocusing quintic nonlinearities is investigated analytically and numerically. It is proved that above some critical beam powers not only one- and two-charged but also multiple-charged stable vortex solitons do exist. A vortex soliton occurs robust with respect to symmetry-breaking modulational instability in the self-defocusing regime provided that its radial profile becomes flattened, so that a self-trapped wave beam gets a pronounced surface. It is demonstrated that the dynamics of a slightly perturbed stable vortex soliton resembles an oscillation of a liquid stream having a surface tension. Using the idea of sustaining effective surface tension for spatial vortex soliton in a media with competing nonlinearities the explanation of a suppression of the modulational instability is proposed.Comment: 4 pages, 3 figures. Submitted to Journal of Optics A. The proceedings of the workshop NATO ARW, Kiev 2003 Singular Optics 200

Cleaning graphene : a first quantum/classical molecular dynamics approach

Graphene outstanding properties created a huge interest in the condensed matter community and unprecedented fundings at the international scale in the hope of application developments. Recently, there have been several reports of incomplete removal of the polymer resists used to transfer as-grown graphene from one substrate to another, resulting in altered graphene transport properties. Finding a large-scale solution to clean graphene from adsorbed residues is highly desirable and one promising possibility would be to use hydrogen plasmas. In this spirit, we couple here quantum and classical molecular dynamics simulations to explore the kinetic energy ranges required by atomic hydrogen to selectively etch a simple residue, a CH3 group, without irreversibly damaging the graphene. For incident energies in the 2-15 eV range, the CH3 radical can be etched by forming a volatile CH4 compound which leaves the surface, either in the CH4 form or breaking into CH3+H fragments, without further defect formation. At this energy, adsorption of H atoms on graphene is possible and further annealing will be required to recover pristine graphene.Comment: 9 figures, 27 page

LIPID PROFILE OF BLOOD SERUM, LIPID PEROXIDATION AND NITROXiDERGIC SYSTEM OF VETERANS OF THE AFGHAN CONFLICT WITH EARLY FORMS OF CHRONIC BRAIN ISCHEMIA

A determination of lipid profile, indices of lipid peroxidation and ergic system in veterans and civilians with early forms of chronic brain ischemia. The data confirming the presence of oxidative stress at cellular membranes showed high antioxidant activity and ergic systems are more pronounced in veterans with DEP-I, which may reflect the growth of nerve tissue hypoxia in the progression of chronic cerebrovascular insufficiency in the background of post-stress disorder

GROWTH OF BIOLOGICAL MARKERS OF AGING AND ALLOSTASIS IN VETERANS OF THE AFGHAN WAR CONFLICT WITH EARLY FORMS OF CHRONIC BRAIN ISCHEMIA

We investigated the rate of biological aging, the levels of stress hormones and regulatory cytokines in Afghan war veterans and civilians with early forms of chronic brain ischemia. The study established acceleration of aging according to biological age indicators, earlier clinical onset of early forms of chronic cerebrovascular diseases associated with the processes of posttraumatic disregulation of cerebral and systemic vascular tone, the accumulation of "allostatic load” in the form of hypercortisolemia, growth regulator and angiogenic cytokines in veterans of the Afghan conflict

New materials based on polylactide modified with silver and carbon ions

An integrated study of poly-L-lactide (PL) synthesis and the physicochemical properties of film surfaces, both modified by silver and carbon ion implantation and also unmodified PL surfaces, has been carried out. Surface modification was done using aMevva-5.Ru metal ion source with ion implantation doses of 1·1014, 1·1015 and 1·1016 ion/cm2. Material characterization was done using NMR, IRS, XPS and AFM. The molecular weight (MW), micro-hardness, surface resistivity, and limiting wetting angle of both un-implanted and implanted samples were measured. The results reveal that degradation of PL macromolecules occurs during ion implantation, followed by CO or CO2 removal and MW decrease. With increasing implantation dose, the glycerol wettability of the PL surface increases but the water affinity decreases (hydrophobic behavior). After silver and carbon ion implantation into the PL samples, the surface resistivity is reduced by several orders of magnitude and a tendency to micro-hardness reductionis induced

The association study of polymorphic variants of hypothalamic-pituitary-adrenal system genes (AVPR1B, OXTR) and aggressive behavior manifestation: a focus on social environment

Considering a multifactorial nature of developing aggression, the present study is aimed to estimate both the genetic- and haplotype-based effects of the OXTR and AVPR1B genes and gene-by-environment interactions in developing A

Observation of attraction between dark solitons

We demonstrate a dramatic change in the interaction forces between dark solitons in nonlocal nonlinear media. We present what we believe is the first experimental evidence of attraction of dark solitons. Our results indicate that attraction should be observable in other nonlocal systems, such as Bose-Einstein condensates with repulsive long-range interparticle interaction

Collapse arrest and soliton stabilization in nonlocal nonlinear media

We investigate the properties of localized waves in systems governed by nonlocal nonlinear Schrodinger type equations. We prove rigorously by bounding the Hamiltonian that nonlocality of the nonlinearity prevents collapse in, e.g., Bose-Einstein condensates and optical Kerr media in all physical dimensions. The nonlocal nonlinear response must be symmetric, but can be of completely arbitrary shape. We use variational techniques to find the soliton solutions and illustrate the stabilizing effect of nonlocality.Comment: 4 pages with 3 figure

ЧАСТО БОЛЕЮЩИЕ ДЕТИ. ВЗГЛЯД ФИЗИОТЕРАПЕВТА

The prevention of frequent respiratory infections in children is one of the urgent issues of modern pediatrics. At present the range of non-drug technologies of prevention of acute respiratory infections (ARI) in children has considerably increased due to the appearance of new effective methods of physical rehabilitation. The article gives a literary review of the main methods of drug prevention of frequent ARI in childhood applied in practical healthcare on the modern stage.Профилактика частых респираторных инфекций у детей является одной из актуальных проблем современной педиатрии. В настоящее время спектр немедикаментозных технологий для профилактики острых респираторных инфекций (ОРИ) у детей значительно расширился за счет возникновения новых эффективных методов физической реабилитации. В статье представлен литературный обзор основных методов немедикаментозной профилактики частых ОРИ в детском возрасте, используемых в практическом здравоохранении на современном этапе

Controls on the composition and lability of dissolved organic matter in Siberia's Kolyma River basin

High-latitude northern rivers export globally significant quantities of dissolved organic carbon (DOC) to the Arctic Ocean. Climate change, and its associated impacts on hydrology and potential mobilization of ancient organic matter from permafrost, is likely to modify the flux, composition, and thus biogeochemical cycling and fate of exported DOC in the Arctic. This study examined DOC concentration and the composition of dissolved organic matter (DOM) across the hydrograph in Siberia's Kolyma River, with a particular focus on the spring freshet period when the majority of the annual DOC load is exported. The composition of DOM within the Kolyma basin was characterized using absorbance-derived measurements (absorbance coefficienta330, specific UV absorbance (SUVA254), and spectral slope ratio SR) and fluorescence spectroscopy (fluorescence index and excitation-emission matrices (EEMs)), including parallel factor analyses of EEMs. Increased surface runoff during the spring freshet led to DOM optical properties indicative of terrestrial soil inputs with high humic-like fluorescence, SUVA254, and low SRand fluorescence index (FI). Under-ice waters, in contrast, displayed opposing trends in optical properties representing less aromatic, lower molecular weight DOM. We demonstrate that substantial losses of DOC can occur via biological (∼30% over 28 days) and photochemical pathways (>29% over 14 days), particularly in samples collected during the spring freshet. The emerging view is therefore that of a more dynamic and labile carbon pool than previously thought, where DOM composition plays a fundamental role in controlling the fate and removal of DOC at a pan-Arctic scale