583 research outputs found

    Assessing the effect of lens mass model in cosmological application with updated galaxy-scale strong gravitational lensing sample

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    By comparing the dynamical and lensing masses of early-type lens galaxies, one can constrain both the cosmological parameters and the density profiles of galaxies. We explore the constraining power on cosmological parameters and the effect of the lens mass model in this method with 161 galaxy-scale strong lensing systems, which is currently the largest sample with both high resolution imaging and stellar dynamical data. We assume a power-law mass model for the lenses, and consider three different parameterizations for γ\gamma (i.e., the slope of the total mass density profile) to include the effect of the dependence of γ\gamma on redshift and surface mass density. When treating δ\delta (i.e., the slope of the luminosity density profile) as a universal parameter for all lens galaxies, we find the limits on the cosmological parameter Ωm\Omega_m are quite weak and biased, and also heavily dependent on the lens mass model in the scenarios of parameterizing γ\gamma with three different forms. When treating δ\delta as an observable for each lens, the unbiased estimate of Ωm\Omega_m can be obtained only in the scenario of including the dependence of γ\gamma on both the redshift and the surface mass density, that is Ωm=0.3810.154+0.185\Omega_m = 0.381^{+0.185}_{-0.154} at 68\% confidence level in the framework of a flat Λ\LambdaCDM model. We conclude that the significant dependencies of γ\gamma on both the redshift and the surface mass density, as well as the intrinsic scatter of δ\delta among the lenses, need to be properly taken into account in this method.Comment: Accepted for publication in MNRAS; 17 pages, 5 figures, 2 table

    The appearance of a merging binary black hole very close to a spinning supermassive black hole

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    The mass and distance of a binary black hole (BBH) are fundamental parameters to measure in gravitational-wave (GW) astronomy. It is well-known that the measurement is affected by cosmological redshift, and recent works also showed that Doppler and gravitational redshifts could further affect the result if the BBH coalesces close to a supermassive black hole (SMBH). Here we consider the additional lensing effect induced by the nearby SMBH on the measurement. We compute the null geodesics originating within 1010 gravitational radii of a Kerr SMBH to determine the redshift and magnification of the GWs emitted by the BBH. We find a positive correlation between redshift and demagnification, which results in a positive correlation between the mass and distance of the BBH in the detector frame. More importantly, we find a higher probability for the signal to appear redshifted and demagnified to a distant observer, rather than blueshifted and magnified. Based on these results, we show that a binary at a cosmological redshift of zcos=(102101)z_{\rm cos}=(10^{-2}-10^{-1}) and composed of BHs of (1020)M(10-20)M_\odot could masquerade as a BBH at a redshift of zcos1z_{\rm cos}\sim1 and containing BHs as large as (44110)M(44-110)M_\odot. In the case of extreme demagnification, we also find that the same BBH could appear to be at zcos>10z_{\rm cos}>10 and contain subsolar-mass BHs. Such an effect, if not accounted for, could bias our understanding of the origin of the BHs detected via GWs

    Basic Public Cultural Services Problems  and Countermeasure Analysis in Rural

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    Overall balanced development of urban and rural culture is an important part of the current public cultural service system, it is one of the basic means of promoting social development. This article from the perspective of the outstanding problems of the rural public cultural service, analyses the basic reasons which restrict the development of the rural public culture, then proposed to strengthen and improve the countermeasure thinking of rural public cultural services

    Improving immunogenicity and safety of flagellin as vaccine carrier by high-density display on virus-like particle surface

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    Flagellin is a protein-based adjuvant that activates toll-like receptor (TLR) 5. Flagellin has been actively explored as vaccine adjuvants and carriers. Preclinical and clinical studies find flagellin-based vaccines have a risk to induce systemic adverse reactions potentially due to its overt activation of TLR5. To improve safety and immunogenicity of flagellin as vaccine carriers, FljB was displayed at high densities on hepatitis b core (HBc) virus-like particle (VLP) surface upon c/e1 loop insertion. FljB-HBc (FH) VLPs showed significantly reduced ability to activate TLR5 or induce systemic interleukin-6 release as compared to FljB. FH VLPs also failed to significantly increase rectal temperature of mice, while FljB could significantly increase rectal temperature of mice. These data indicated systemic safety of FljB could be significantly improved by high-density display on HBc VLP surface. Besides improved safety, FH VLPs and FljB similarly boosted co-administered ovalbumin immunization and FH VLPs were found to induce two-fold higher anti-FljB antibody titer than FljB. These data indicated preserved adjuvant potency and improved immunogenicity after high-density display of FljB on HBc VLP surface. Consistent with the high immunogenicity, FH VLPs were found to be more efficiently taken up by bone marrow-derived dendritic cells and stimulate more potent dendritic cell maturation than FljB. Lastly, FH VLPs were found to be a more immunogenic carrier than FljB, HBc VLPs, or the widely used keyhole limpet hemocyanin for nicotine vaccine development with a good local and systemic safety. Our data support FH VLPs to be a potentially safer and more immunogenic carrier than FljB for vaccine development

    Evidence for Dirac Fermions in a honeycomb lattice based on silicon

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    Silicene, a sheet of silicon atoms in a honeycomb lattice, was proposed to be a new Dirac-type electron system similar as graphene. We performed scanning tunneling microscopy and spectroscopy studies on the atomic and electronic properties of silicene on Ag(111). An unexpected 3×3\sqrt{3}\times \sqrt{3} reconstruction was found, which is explained by an extra-buckling model. Pronounced quasi-particle interferences (QPI) patterns, originating from both the intervalley and intravalley scattering, were observed. From the QPI patterns we derived a linear energy-momentum dispersion and a large Fermi velocity, which prove the existence of Dirac Fermions in silicene.Comment: 6 pages, 4 figure
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