988 research outputs found

    Viscosity in the excluded volume hadron gas model

    Full text link
    The shear viscosity η\eta in the van der Waals excluded volume hadron-resonance gas model is considered. For the shear viscosity the result of the non-relativistic gas of hard-core particles is extended to the mixture of particles with different masses, but equal values of hard-core radius r. The relativistic corrections to hadron average momenta in thermal equilibrium are also taken into account. The ratio of the viscosity η\eta to the entropy density s is studied. It monotonously decreases along the chemical freeze-out line in nucleus-nucleus collisions with increasing collision energy. As a function of hard-core radius r, a broad minimum of the ratio η/s0.3\eta/s\approx 0.3 near r0.5r \approx 0.5 fm is found at high collision energies. For the charge-neutral system at T=Tc=180T=T_c=180 MeV, a minimum of the ratio η/s0.24\eta/s\cong 0.24 is reached for r0.53r\cong 0.53 fm. To justify a hydrodynamic approach to nucleus-nucleus collisions within the hadron phase the restriction from below, r  0.2r~ \ge ~0.2 fm, on the hard-core hadron radius should be fulfilled in the excluded volume hadron-resonance gas.Comment: 12 pages, 3 figure

    Renormalization group study of the four-body problem

    Full text link
    We perform a renormalization group analysis of the non-relativistic four-boson problem by means of a simple model with pointlike three- and four-body interactions. We investigate in particular the unitarity point where the scattering length is infinite and all energies are at the atom threshold. We find that the four-body problem behaves truly universally, independent of any four-body parameter. Our findings confirm the recent conjectures of Platter et al. and von Stecher et al. that the four-body problem is universal, now also from a renormalization group perspective. We calculate the corresponding relations between the four- and three-body bound states, as well as the full bound state spectrum and comment on the influence of effective range corrections.Comment: 11 pages, 6 figures; v2: revised and published versio

    Reduced-order models of the Martian atmospheric dynamics

    Get PDF
    In this paper we explore the possibility of deriving low-dimensional models of the dynamics of the Martian atmosphere. The analysis consists of a Proper Orthogonal Decomposition (POD) of the atmospheric streamfunction after first decomposing the vertical structure with a set of eigenmodes. The vertical modes were obtained from the quasi-geostrophic vertical structure equation. The empirical orthogonal functions (EOFs) were optimized to represent the atmospheric total energy. The total energy was used as the criterion to retain those modes with large energy content and discard the rest. The principal components (PCs) were analysed by means of Fourier analysis, so that the dominant frequencies could be identified. It was possible to observe the strong influence of the diurnal cycle and to identify the motion and vacillation of baroclinic waves

    Vitamin D as One of Predicators of the Stable Viral Response to Antiviral Therapy in Patients with Chronis Hepatitis С

    Full text link
    Chronic hepatitis C (CHC) it is not exceptionally medical problem but a significant social and economic threat, taking into account the unfavorable consequences of this disease: cirrhosis and hepatocellular carcinoma. And as a result - the high level of disability. In the article are presented the results of examination of 41 patients with chronic hepatitis C, with 1 genotype, who received the antiviral therapy (AVT). All patients underwent determination of the level of 5-hydroxycholeсalсeferol (25-OH vit D3), vitamin D and also the study of IL-28B polymorphism as the one of predicators of response to AVT. It was demonstrated, that in patients with hepatitis was observed the deficit of 25-OH vit D3 and general vitamin D. It was established, that in patients with the normal 25-OH vit D3 level SVR (stable viral response) was observed in 1,4 times more often than in patients with deficit of 25-OH vit D3. That is the level of 25-OH vit D3 can be considered as a predicator of SVR to AVT

    Persistent currents in multicomponent Tomonaga-Luttinger liquid: application to mesoscopic semiconductor ring with spin-orbit interaction

    Full text link
    We study persistent currents in semiconductor ballistic rings with spin-orbit Rashba interaction. We use as a working model the multicomponent Tomonaga-Luttinger liquid which arises due to the nonparabolic dispersion relations of electrons in the rings with rather strong spin-orbit coupling. This approach predicts some new characteristic features of persistent currents, which may be observed in experimental studies of semiconductor ballistic rings.Comment: 13 pages, 8 figure
    corecore