30,172 research outputs found

    No association of CTLA-4 polymorphisms with susceptibility to Behcet disease

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    Background: Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) is a key negative regulator of T lymphocytes and has been shown to be associated with a number of autoimmune diseases. The present study was performed to assess the association between CTLA-4 polymorphisms and Behcet disease (BD) in Chinese patients. Methods: Two hundred and twenty-eight BD patients and 207 controls were analysed for four single nucleotide polymorphisms (SNPs) (21661A/G, 2318C/T, + 49G/A and CT60G/A) in the CTLA-4 gene by PCR-restriction fragment length polymorphism (RFLP) analysis. The association between SNP +49A/G and BD in Chinese population as well as other ethnic groups was analysed by meta-analysis. Results: No association could be detected between CTLA-4 SNPs or haplotypes and BD. Also, no association was observed between CTLA-4 polymorphisms and BD subgroups, stratified by clinical features. A meta-analysis showed that there was no heterogeneity between studies (p = 0.60, I-2 = 0%) and that CTLA-4 SNP + 49 was not associated with BD (overall effect: Z = 0.26, p = 0.79). Conclusion: This study and a meta-analysis failed to demonstrate any association between the tested CTLA-4 polymorphisms and B

    A Sino-German 6cm polarisation survey of the Galactic plane IX. HII regions

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    Large-scale radio continuum surveys provide data to get insights into the physical properties of radio sources. HII regions are prominent radio sources produced by thermal emission of ionised gas around young massive stars. We identify and analyse HII regions in the Sino-German 6cm polarisation survey of the Galactic plane. Objects with flat radio continuum spectra together with infrared and/or Halpha emission were identified as HII regions. For HII regions with small apparent sizes, we cross-matched the 6cm small-diameter source catalogue with the radio HII region catalogue compiled by Paladini and the infrared HII region catalogue based on the WISE data. Extended HII regions were identified by eye by overlaying the Paladini and the WISE HII regions onto the 6cm survey images for coincidences. The TT-plot method was employed for spectral index verification. A total of 401 HII regions were identified and their flux densities were determined with the Sino-German 6cm survey data. In the surveyed area, 76 pairs of sources are found to be duplicated in the Paladini HII region catalogue, mainly due to the non-distinction of previous observations with different angular resolutions, and 78 objects in their catalogue are misclassified as HII regions, being actually planetary nebulae, supernova remnants or extragalactic sources that have steep spectra. More than 30 HII regions and HII region candidates from our 6cm survey data, especially extended ones, do not have counterparts in the WISE HII region catalogue, of which 9 are identified for the first time. Based on the newly derived radio continuum spectra and the evidence of infrared emission, the previously identified SNRs G11.1-1.0, G20.4+0.1 and G16.4-0.5 are believed to be HII regions.Comment: version after some minor corrections and language editing, full Table 2 - 5 will appear in CDS, accepted for publication in A&

    On Singularity Formation of a Nonlinear Nonlocal System

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    We investigate the singularity formation of a nonlinear nonlocal system. This nonlocal system is a simplified one-dimensional system of the 3D model that was recently proposed by Hou and Lei in [13] for axisymmetric 3D incompressible Navier-Stokes equations with swirl. The main difference between the 3D model of Hou and Lei and the reformulated 3D Navier-Stokes equations is that the convection term is neglected in the 3D model. In the nonlocal system we consider in this paper, we replace the Riesz operator in the 3D model by the Hilbert transform. One of the main results of this paper is that we prove rigorously the finite time singularity formation of the nonlocal system for a large class of smooth initial data with finite energy. We also prove the global regularity for a class of smooth initial data. Numerical results will be presented to demonstrate the asymptotically self-similar blow-up of the solution. The blowup rate of the self-similar singularity of the nonlocal system is similar to that of the 3D model.Comment: 28 pages, 9 figure

    Kondo effect in coupled quantum dots with RKKY interaction: Finite temperature and magnetic field effects

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    We study transport through two quantum dots coupled by an RKKY interaction as a function of temperature and magnetic field. By applying the Numerical Renormalization Group (NRG) method we obtain the transmission and the linear conductance. At zero temperature and magnetic field, we observe a quantum phase transition between the Kondo screened state and a local spin singlet as the RKKY interaction is tuned. Above the critical RKKY coupling the Kondo peak is split. However, we find that both finite temperature and magnetic field restore the Kondo resonance. Our results agree well with recent transport experiments on gold grain quantum dots in the presence of magnetic impurities.Comment: 4 pages, 5 figure

    Analytical solutions of the lattice Boltzmann BGK model

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    Analytical solutions of the two dimensional triangular and square lattice Boltzmann BGK models have been obtained for the plain Poiseuille flow and the plain Couette flow. The analytical solutions are written in terms of the characteristic velocity of the flow, the single relaxation time Ï„\tau and the lattice spacing. The analytic solutions are the exact representation of these two flows without any approximation.Comment: 10 pages, no postscript figure provide

    Eigenvalues of Ruijsenaars-Schneider models associated with An−1A_{n-1} root system in Bethe ansatz formalism

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    Ruijsenaars-Schneider models associated with An−1A_{n-1} root system with a discrete coupling constant are studied. The eigenvalues of the Hamiltonian are givein in terms of the Bethe ansatz formulas. Taking the "non-relativistic" limit, we obtain the spectrum of the corresponding Calogero-Moser systems in the third formulas of Felder et al [20].Comment: Latex file, 25 page

    Enhanced b→sgb\to sg Decay, Inclusive η′\eta^\prime Production, and the Gluon Anomaly

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    The experimental hint of large B→η′+XsB\to \eta^\prime + X_s is linked to the b→sb\to s penguins via the gluon anomaly. Using running αs\alpha_s in the η′\eta^\prime-gg-gg coupling, the standard b→sg∗b\to sg^* penguin alone seems insufficient, calling for the need of dipole b→sgb\to sg at 10% level from new physics, which could also resolve the Bs.l.{\cal B}_{s.l.} and charm counting problems. The intereference of standard and new physics contributions may result in direct CP asymmetries at 10% level, which could be observed soon at B Factories.Comment: 12 pages, revtex, 3 figs. (version to appear in Phys. Rev. Lett.
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