2,093 research outputs found

    Global gyrokinetic simulations of intrinsic rotation in ASDEX Upgrade Ohmic L-mode plasmas

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    Non-linear, radially global, turbulence simulations of ASDEX Upgrade (AUG) plasmas are performed and the nonlinear generated intrinsic flow shows agreement with the intrinsic flow gradients measured in the core of Ohmic L-mode plasmas at nominal parameters. Simulations utilising the kinetic electron model show hollow intrinsic flow profiles as seen in a predominant number of experiments performed at similar plasma parameters. In addition, significantly larger flow gradients are seen than in a previous flux-tube analysis (Hornsby et al {\it Nucl. Fusion} (2017)). Adiabatic electron model simulations can show a flow profile with opposing sign in the gradient with respect to a kinetic electron simulation, implying a reversal in the sign of the residual stress due to kinetic electrons. The shaping of the intrinsic flow is strongly determined by the density gradient profile. The sensitivity of the residual stress to variations in density profile curvature is calculated and seen to be significantly stronger than to neoclassical flows (Hornsby et al {\it Nucl. Fusion} (2017)). This variation is strong enough on its own to explain the large variations in the intrinsic flow gradients seen in some AUG experiments. Analysis of the symmetry breaking properties of the turbulence shows that profile shearing is the dominant mechanism in producing a finite parallel wave-number, with turbulence gradient effects contributing a smaller portion of the parallel wave-vector

    Sinusoidal cells and cytokine response in the tetrachloromethane-induced hepatotoxicity and an approach to its correction

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    High occurence of liver diseases (toxic, viral hepatitis, liver failure, cirrhosis) requires urgent search of new methods for management of the hepatobiliary diseases. At the present time, the role of immune mechanisms in pathogenesis of diffuse toxic liver damage is not finally clarified. The model of toxic hepatitis induced by carbon tetrachloride (CCl4) is widely known, but this approach allows us to perform complex evaluation and develop the methods for adequate correction of liver disorders in experimental model, which is not always feasible in clinical setting. To design a model of diffuse toxic liver damage, the CCl4 oil solution was used, having been administered intraperitoneally to experimental animals, at a single dose of 50 mg per 100 g body mass. Aiming for correction of toxic liver damage, the injections of aminophthalhydrazide (APH) to experimental animals were carried out intramuscularly at the dose of 2 mg/kg over the terms of experiment. An evaluation of the role of sinusoidal cells (SC) and cytokine production at the local and systemic level were carried out in the model of toxic liver damage caused by CCl4 and its correction by APH treatment. In the course of developing diffuse toxic liver damage induced by CCl4, the production of proinflammatory cytokines TNFα, IL-1α and IL-18 was enhanced at the local level, whereas an increase in TNFα concentration was observed in blood plasma. Following aminophthalhydrazide (APH) administration, the concentrations of proinflammatory cytokines (TNFα and IL-18) decreased at system level, along with locally decreased levels of IL-6 and IFNγ. Changes in the functional state of immunocompetent cells, which include sinusoidal cells (SC), have a significant impact on the development of pathological processes in the liver. The results of our study presume that, over the early periods of toxic impact upon liver tissue, the number of SCs increases both due to influx of blood monocytes and mature macrophages from the peritoneal cavity that enter the injury site directly via mesothelial layer. The SCs provide phagocytosis of damaged hepatocytes and contribute to resolution of the inflammatory process. Modulation of the macrophage activities by APH contributes to increased amounts of SCs at the early stages, and stabilizes their quantities after 2 weeks of APH injections. Change in the numbers of liver SCs during toxic damage affects the production of cytokines. A direct effect of APH upon the SCs may change the production of regulatory factors and compensate the insufficient rate of recovery processes after the toxic damage. © 2019, SPb RAACI

    Ferromagnetic Polarons in La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3

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    Unrestricted Hartree-Fock calculations on La0.5Ca0.5MnO3 and La0.33Ca0.67MnO3 in the full magnetic unit cell show that the magnetic ground states of these compounds consist of 'ferromagnetic molecules' or polarons ordered in herring-bone patterns. Each polaron consists of either three or five Mn ions separated by O- ions with a magnetic moment opposed to those of the Mn ions. Ferromagnetic coupling within the polarons is strong while coupling between them is relatively weak. Magnetic moments on the Mn ions range between 3.8 and 3.9 Bohr magnetons in La0.5Ca0.5MnO3 and moments on the O- ions are -0.7 Bohr magnetons. Each polaron has a net magnetic moment of 7.0 Bohr magnetons, in good agreement with recently reported magnetisation measurements from electron microscopy. The polaronic nature of the electronic structure reported here is obviously related to the Zener polaron model recently proposed for Pr0.6Ca0.4MnO3 on the basis of neutron scattering data.Comment: 4 pages 5 figure

    Retention of Two-Band Superconductivity in Highly Carbon-Doped MgB2

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    Tunneling data on MgB_{1.8}C_{0.2} show a reduction in the energy gap of the pi-bands by a factor of two from undoped MgB2 that is consistent with the Tc reduction, but inconsistent with the expectations of the dirty limit. Dirty-limit theory for undoped MgB2 predicts a single gap about three times larger than measured and a reduced Tc comparable to that measured. Our heavily-doped samples exhibit a uniform dispersion of C suggestive of significantly enhanced scattering, and we conclude that the retention of two-band superconductivity in these samples is caused by a selective suppression of interband scattering.Comment: 4 pages, 4 figures; added one figure, added one reference, minor changes to the text, manuscript accepted for publication as a Phys. Rev. B Rapid Communicatio

    Electronic Structure and Valence Band Spectra of Bi4Ti3O12

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    The x-ray photoelectron valence band spectrum and x-ray emission valence-band spectra (Ti K _beta_5, Ti L_alpha, O K_alpha) of Bi4Ti3O12 are presented (analyzed in the common energy scale) and interpreted on the basis of a band-structure calculation for an idealized I4/mmm structure of this material.Comment: 6 pages + 7 PostScript figures, RevTex3.0, to be published in Phys.Rev.B52 (Oct.95). Figures also available via anonymous ftp at ftp://ftp.physik.uni-osnabrueck.de/pub/apostnik/BiTiO

    A self-interaction corrected pseudopotential scheme for magnetic and strongly-correlated systems

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    Local-spin-density functional calculations may be affected by severe errors when applied to the study of magnetic and strongly-correlated materials. Some of these faults can be traced back to the presence of the spurious self-interaction in the density functional. Since the application of a fully self-consistent self-interaction correction is highly demanding even for moderately large systems, we pursue a strategy of approximating the self-interaction corrected potential with a non-local, pseudopotential-like projector, first generated within the isolated atom and then updated during the self-consistent cycle in the crystal. This scheme, whose implementation is totally uncomplicated and particularly suited for the pseudopotental formalism, dramatically improves the LSDA results for a variety of compounds with a minimal increase of computing cost.Comment: 18 pages, 14 figure

    Observation of Two Resonant Structures in e+e- to pi+ pi- psi(2S) via Initial State Radiation at Belle

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    The cross section for e+e- to pi+ pi- psi(2S) between threshold and \sqrt{s}=5.5 GeV is measured using 673 fb^{-1} of data on and off the \Upsilon(4S) resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the pi+ pi- psi(2S) invariant mass distribution, one at 4361\pm 9\pm 9 MeV/c2 with a width of 74\pm 15\pm 10 MeV/c2, and another at 4664\pm 11\pm 5 MeV/c2 with a width of 48\pm 15\pm 3 MeV/c2, if the mass spectrum is parameterized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.Comment: 10 pages, 5 figures, 2 tables, version to appear in Phys. Rev. Let

    Study of B -> D** l nu with full reconstruction tagging

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    We report a study of semileptonic B decays to P-wave D** mesons. Semileptonic decay to D*_2 meson is observed for the first time and its product branching ratio is measured to be Br(B+ -> anti-D*0_2 l+nu) x Br(anti-D*0_2 -> D- pi+) = 0.22 +- 0.03(stat.) +- 0.04(syst.)%. The result is obtained using the fully reconstructed B tags from a data sample that contains 657 millions BB-bar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+ e- collider.Comment: 12 pages, 4 figures, submitted to PRD(RC

    Time-dependent CP Asymmetries in B0KS0ρ0γB^0\to K^0_S\rho^0\gamma Decays

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    We report the first measurement of CP-violation parameters in B^0 -> K_S^0\rho^0\gamma decays based on 657 million B\bar B pairs collected with the Belle detector at the KEKB asymmetric-energy collider. We measure the time-dependent CP violating parameter S_{K_S^0\rho^0\gamma}= 0.11 +/- 0.33(stat.)^{+0.05}_{-0.09}(syst.). We also obtain the effective direct CP violating parameter A_eff=0.05 +/- 0.18(stat.) +/- 0.06(syst.) for m_{K_S\pi^+\pi^-}<1.8 GeV/c^2 and 0.6 GeV/c^2<m_{\pi^+\pi^-}<0.9 GeV/c^2.Comment: 6 pages, 3 figures, to be submitted to PR
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