The influenza virus neuraminidase inhibitor produced by Staphylococcus aureus

The glycoproteinic complex has been isolated from the Staphylococcus aureus culture fluid possessing an activity inhibiting influenza virus neuraminidase. Two fractions have been further purified containing different monosugars components, the first one has been shown to contain mannose, glucose, rhamnose, glucosamine, and galactosamine, while rhamnose is absent in the second fraction, A component of fraction 1 inhibits the neuraminidase activity and at the same time enhances the virus hemagglutinating activity more strongly comparing to the fraction 2. Some chemical modifications of the substances of the fractions studied (periodate oxidation, protease pretreatment, and delipidization) prove the carbohydrate component of the complex to be responsible for its antineuraminidase activity. The protease pretreatment decreases twice the antineuraminidase activity of the fraction 2 having no influence on this activity of the fraction 1.З культурального середовища золотистого стафілокока (S. aureus) виділено гліколіпопротеїновий комплекс з активністю, що гальмує ней рамінідазу вірусу грипу. Очищено дві фракції з різним вмістом моносахаридів. Показано, що фракція І міс­тить манозу, глюкозу, рамнозу, глюкозамін та галактозамін; друга – всі ці моносахариди, крім рамнози. Речовина з фракції 1 гальмує нейрамінідазну активність та одночасно посилює гемаглютинативну активність вірусу значно сильніше, ніж речовина з фракції 2. Ряд хімічних модифікацій вивчених речовин (перйодатне окислення, обробка протеазою та деліпідизація) підтверджують роль вуглеводного компонента комплексу у здійсненні його антинейрамінідазної дії; обробка протеазою вдвічі знижує антинейрамінідазну активність фракції 2, не впливаючи на таку ж активність фракції 1.Из культуральной среды S. aureus выделен гликолипопротеиновый комплекс с активностью, ингибирующей нейраминидазную активность вируса гриппа. Получены две фракции с различным содержанием моносахаридов, первая из которых включает маннозу, глюкозу, рамнозу, глюкозамин и галактозамин; вто­рая – все эти моносахариды, кроме римнозы. Вещество, содержащееся во фракции I, ингибирует нейраминидазную активность и в то же время усиливает гемагглютинирующую активность вируса гриппа значительно более выражению, чем вещество из фракции 2. Ряд химических модификаций изучаемых фракций (перйодатное окисление, обработка протеазой и делипидизация) доказывает роль углеводного компонента ком­плекса в его антинейраминидазной активности; при этом обработка протеазой вдвое снижает антинейраминидазную активность фракции 2, не влияя на подобную активность фракции 1

The quantum dilogarithm and representations quantum cluster varieties

We construct, using the quantum dilogarithm, a series of *-representations of quantized cluster varieties. This includes a construction of infinite dimensional unitary projective representations of their discrete symmetry groups - the cluster modular groups. The examples of the latter include the classical mapping class groups of punctured surfaces. One of applications is quantization of higher Teichmuller spaces. The constructed unitary representations can be viewed as analogs of the Weil representation. In both cases representations are given by integral operators. Their kernels in our case are the quantum dilogarithms. We introduce the symplectic/quantum double of cluster varieties and related them to the representations.Comment: Dedicated to David Kazhdan for his 60th birthday. The final version. To appear in Inventiones Math. The last Section of the previous versions was removed, and will become a separate pape

Some Aspects of Rotational and Magnetic Energies for a Hierarchy of Celestial Objects

Celestial objects, from earth like planets to clusters of galaxies, possess angular momentum and magnetic fields. Here we compare the rotational and magnetic energies of a whole range of these celestial objects together with their gravitational self energies and find a number of interesting relationships. The celestial objects, due to their magnetic fields, also posses magnetic moments. The ratio of magnetic moments of these objects with the nuclear magnetic moments also exhibits interesting trends. We also compare their gyromagnetic ratio which appears to fall in a very narrow range for the entire hierarchy of objects. Here we try to understand the physical aspects implied by these observations and the origin of these properties in such a wide range of celestial objects, spanning some twenty orders in mass, magnetic field and other parameters.Comment: 12 pages, 37 equation

Kinks in the Presence of Rapidly Varying Perturbations

Dynamics of sine-Gordon kinks in the presence of rapidly varying periodic perturbations of different physical origins is described analytically and numerically. The analytical approach is based on asymptotic expansions, and it allows to derive, in a rigorous way, an effective nonlinear equation for the slowly varying field component in any order of the asymptotic procedure as expansions in the small parameter $\omega^{-1}$, $\omega$ being the frequency of the rapidly varying ac driving force. Three physically important examples of such a dynamics, {\em i.e.}, kinks driven by a direct or parametric ac force, and kinks on rotating and oscillating background, are analysed in detail. It is shown that in the main order of the asymptotic procedure the effective equation for the slowly varying field component is {\em a renormalized sine-Gordon equation} in the case of the direct driving force or rotating (but phase-locked to an external ac force) background, and it is {\em the double sine-Gordon equation} for the parametric driving force. The properties of the kinks described by the renormalized nonlinear equations are analysed, and it is demonstrated analytically and numerically which kinds of physical phenomena may be expected in dealing with the renormalized, rather than the unrenormalized, nonlinear dynamics. In particular, we predict several qualitatively new effects which include, {\em e.g.}, the perturbation-inducedComment: New copy of the paper of the above title to replace the previous one, lost in the midst of the bulletin board. RevTeX 3.

Crystallization of the ordered vortex phase in high temperature superconductors

The Landau-Khalatnikov time-dependent equation is applied to describe the crystallization process of the ordered vortex lattice in high temperature superconductors after a sudden application of a magnetic field. Dynamic coexistence of a stable ordered phase and an unstable disordered phase, with a sharp interface between them, is demonstrated. The transformation to the equilibrium ordered state proceeds by movement of this interface from the sample center toward its edge. The theoretical analysis dictates specific conditions for the creation of a propagating interface, and provides the time scale for this process.Comment: 8 pages and 3 figures; to be published in Phys. Rev. B (Rapid Communications section

Anisotropic dark energy stars

A model of compact object coupled to inhomogeneous anisotropic dark energy is studied. It is assumed a variable dark energy that suffers a phase transition at a critical density. The anisotropic Lambda-Tolman-Oppenheimer-Volkoff equations are integrated to know the structure of these objects. The anisotropy is concentrated on a thin shell where the phase transition takes place, while the rest of the star remains isotropic. The family of solutions obtained depends on the coupling parameter between the dark energy and the fermion matter. The solutions share several features in common with the gravastar model. There is a critical coupling parameter that gives non-singular black hole solutions. The mass-radius relations are studied as well as the internal structure of the compact objects. The hydrodynamic stability of the models is analyzed using a standard test from the mass-radius relation. For each permissible value of the coupling parameter there is a maximum mass, so the existence of black holes is unavoidable within this model.Comment: 12 pages, 6 figures, final manuscript, Accepted for publication in Astrophysics & Space Scienc

Four-fermion interaction from torsion as dark energy

The observed small, positive cosmological constant may originate from a four-fermion interaction generated by the spin-torsion coupling in the Einstein-Cartan-Sciama-Kibble gravity if the fermions are condensing. In particular, such a condensation occurs for quark fields during the quark-gluon/hadron phase transition in the early Universe. We study how the torsion-induced four-fermion interaction is affected by adding two terms to the Dirac Lagrangian density: the parity-violating pseudoscalar density dual to the curvature tensor and a spinor-bilinear scalar density which measures the nonminimal coupling of fermions to torsion.Comment: 6 pages; published versio

Magnetism in Dense Quark Matter

We review the mechanisms via which an external magnetic field can affect the ground state of cold and dense quark matter. In the absence of a magnetic field, at asymptotically high densities, cold quark matter is in the Color-Flavor-Locked (CFL) phase of color superconductivity characterized by three scales: the superconducting gap, the gluon Meissner mass, and the baryonic chemical potential. When an applied magnetic field becomes comparable with each of these scales, new phases and/or condensates may emerge. They include the magnetic CFL (MCFL) phase that becomes relevant for fields of the order of the gap scale; the paramagnetic CFL, important when the field is of the order of the Meissner mass, and a spin-one condensate associated to the magnetic moment of the Cooper pairs, significant at fields of the order of the chemical potential. We discuss the equation of state (EoS) of MCFL matter for a large range of field values and consider possible applications of the magnetic effects on dense quark matter to the astrophysics of compact stars.Comment: To appear in Lect. Notes Phys. "Strongly interacting matter in magnetic fields" (Springer), edited by D. Kharzeev, K. Landsteiner, A. Schmitt, H.-U. Ye

Photon mixing in universes with large extra-dimensions

In presence of a magnetic field, photons can mix with any particle having a two-photon vertex. In theories with large compact extra-dimensions, there exists a hierachy of massive Kaluza-Klein gravitons that couple to any photon entering a magnetic field. We study this mixing and show that, in comparison with the four dimensional situation where the photon couples only to the massless graviton, the oscillation effect may be enhanced due to the existence of a large number of Kaluza-Klein modes. We give the conditions for such an enhancement and then investigate the cosmological and astrophysical consequences of this phenomenon; we also discuss some laboratory experiments. Axions also couple to photons in the same way; we discuss the effect of the existence of bulk axions in universes with large extra-dimensions. The results can also be applied to neutrino physics with extra-dimensions.Comment: 41 pages, LaTex, 6 figure

Interacting new agegraphic viscous dark energy with varying GG

We consider the new agegraphic model of dark energy with a varying gravitational constant, $G$, in a non-flat universe. We obtain the equation of state and the deceleration parameters for both interacting and noninteracting new agegraphic dark energy. We also present the equation of motion determining the evolution behavior of the dark energy density with a time variable gravitational constant. Finally, we generalize our study to the case of viscous new agegraphic dark energy in the presence of an interaction term between both dark components.Comment: 12 pages, accepted for publication in IJTP (2010