481 research outputs found

    Membrane-associated heparan sulfate is not required for rAAV-2 infection of human respiratory epithelia

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    BACKGROUND: Adeno-associated virus type 2 (AAV-2) attachment and internalization is thought to be mediated by host cell membrane-associated heparan sulfate proteoglycans (HSPG). Lack of HSPG on the apical membrane of respiratory epithelial cells has been identified as a reason for inefficient rAAV-2 infection in pulmonary applications in-vivo. The aim of this investigation was to determine the necessity of cell membrane HSPG for efficient infection by rAAV-2. RESULTS: Rates of transduction with rAAV2-CMV-EGFP3 in several different immortalized airway epithelial cell lines were determined at different multiplicities of infection (MOI) before and after removal of membrane HSPG by heparinase III. Removal of HSPG decreased the efficacy of infection with rAAV2 by only 30–35% at MOI ≀ 100 for all of respiratory cell lines tested, and had even less effect at an MOI of 1000. Studies in mutant Chinese Hamster Ovary cell lines known to be completely deficient in surface HSPG also demonstrated only moderate effect of absence of HSPG on rAAV-2 infection efficacy. However, mutant CHO cells lacking all membrane proteoglycans demonstrated dramatic reduction in susceptibility to rAAV-2 infection, suggesting a role of membrane glycosaminoglycans other than HSPG in mediating rAAV-2 infection. CONCLUSION: Lack of cell membrane HSPG in pulmonary epithelia and other cell lines results in only moderate decrease in susceptibility to rAAV-2 infection, and this decrease may be less important at high MOIs. Other cell membrane glycosaminoglycans can play a role in permitting attachment and subsequent rAAV-2 internalization. Targeting alternative membrane glycosaminoglycans may aid in improving the efficacy of rAAV-2 for pulmonary applications

    Parton Energy Loss with Detailed Balance

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    Stimulated gluon emission and thermal absorption in addition to induced radiation are considered for an energetic parton propagating inside a quark- gluon plasma. In the presence of thermal gluons, stimulated emission reduces while absorption increases the parton's energy. The net effect is a reduction of the parton energy loss. Though decreasing asymptotically as T/ET/E with the parton energy, the relative reduction is found to be important for intermediate energies. The modified energy dependence of the energy loss will affect the shape of suppression of moderately high pTp_T hadrons due to jet quenching in high-energy heavy-ion collisions.Comment: 4 pages in RevTex with 1 postscript figure. Some typos are corrected and new comments are adde

    A study on the anomaly of pp over π\pi ratios in Au+AuAu+Au collisions with jet quenching

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    The ratios of p/πp/\pi at large transverse momentum in central Au+AuAu+Au collisions at RHIC are studied in the framework of jet quenching based on a next-to-leading order pQCD parton model. It is shown that theoretical calculations with a gluon energy loss larger than the quark energy loss will naturally lead to a smaller p/πp/\pi ratios at large transverse momentum in Au+AuAu+Au collisions than those in p+pp+p collisions at the same energy. Scenarios with equal energy losses for gluons and quarks and a strong jet conversion are both explored and it is demonstrated in both scenarios p/πp/\pi ratios at high pTp_T in central Au+AuAu+Au collisions are enhanced and the calculated ratios of protons over pions approach to the experimental measurements. However, pˉ/p{\bar p}/p in the latter scenario is found to fit data better than that in the former scenario.Comment: 20 pages, 13 figures; revised version; accepted for publication in Journal of Physics

    The MUSE-Wide Survey: Survey Description and First Data Release

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    We present the MUSE-Wide survey, a blind, 3D spectroscopic survey in the CANDELS/GOODS-S and CANDELS/COSMOS regions. Each MUSE-Wide pointing has a depth of 1 hour and hence targets more extreme and more luminous objects over 10 times the area of the MUSE-Deep fields (Bacon et al. 2017). The legacy value of MUSE-Wide lies in providing "spectroscopy of everything" without photometric pre-selection. We describe the data reduction, post-processing and PSF characterization of the first 44 CANDELS/GOODS-S MUSE-Wide pointings released with this publication. Using a 3D matched filtering approach we detected 1,602 emission line sources, including 479 Lyman-α\alpha (Lya) emitting galaxies with redshifts 2.9â‰Čzâ‰Č6.32.9 \lesssim z \lesssim 6.3. We cross-match the emission line sources to existing photometric catalogs, finding almost complete agreement in redshifts and stellar masses for our low redshift (z < 1.5) emitters. At high redshift, we only find ~55% matches to photometric catalogs. We encounter a higher outlier rate and a systematic offset of Δ\Deltaz≃\simeq0.2 when comparing our MUSE redshifts with photometric redshifts. Cross-matching the emission line sources with X-ray catalogs from the Chandra Deep Field South, we find 127 matches, including 10 objects with no prior spectroscopic identification. Stacking X-ray images centered on our Lya emitters yielded no signal; the Lya population is not dominated by even low luminosity AGN. A total of 9,205 photometrically selected objects from the CANDELS survey lie in the MUSE-Wide footprint, which we provide optimally extracted 1D spectra of. We are able to determine the spectroscopic redshift of 98% of 772 photometrically selected galaxies brighter than 24th F775W magnitude. All the data in the first data release - datacubes, catalogs, extracted spectra, maps - are available on the website https://musewide.aip.de. [abridged]Comment: 25 pages 15+1 figures. Accepted, A&A. Comments welcom

    Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18

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    Combining the precise parallaxes and optical photometry delivered by Gaia's second data release (Gaia DR2) with the photometric catalogues of PanSTARRS-1, 2MASS, and AllWISE, we derive Bayesian stellar parameters, distances, and extinctions for 265 million stars brighter than G=18. Because of the wide wavelength range used, our results substantially improve the accuracy and precision of previous extinction and effective temperature estimates. After cleaning our results for both unreliable input and output data, we retain 137 million stars, for which we achieve a median precision of 5% in distance, 0.20 mag in V-band extinction, and 245 K in effective temperature for G<14, degrading towards fainter magnitudes (12%, 0.20 mag, and 245 K at G=16; 16%, 0.23 mag, and 260 K at G=17, respectively). We find a very good agreement with the asteroseismic surface gravities and distances of 7000 stars in the Kepler, the K2-C3, and the K2-C6 fields, with stellar parameters from the APOGEE survey, as well as with distances to star clusters. Our results are available through the ADQL query interface of the Gaia mirror at the Leibniz-Institut f\"{u}r Astrophysik Potsdam (gaia.aip.de) and as binary tables at data.aip.de. As a first application, in this paper we provide distance- and extinction-corrected colour-magnitude diagrams, extinction maps as a function of distance, and extensive density maps, demonstrating the potential of our value-added dataset for mapping the three-dimensional structure of our Galaxy. In particular, we see a clear manifestation of the Galactic bar in the stellar density distributions, an observation that can almost be considered a direct imaging of the Galactic bar.Comment: 25 pages, 23 figures + appendix, accepted for publication in A&A. Data (doi:10.17876/gaia/dr.2/51) are available through ADQL queries at gaia.aip.d

    Pathway to the Square Kilometre Array - The German White Paper -

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    The Square Kilometre Array (SKA) is the most ambitious radio telescope ever planned. With a collecting area of about a square kilometre, the SKA will be far superior in sensitivity and observing speed to all current radio facilities. The scientific capability promised by the SKA and its technological challenges provide an ideal base for interdisciplinary research, technology transfer, and collaboration between universities, research centres and industry. The SKA in the radio regime and the European Extreme Large Telescope (E-ELT) in the optical band are on the roadmap of the European Strategy Forum for Research Infrastructures (ESFRI) and have been recognised as the essential facilities for European research in astronomy. This "White Paper" outlines the German science and R&D interests in the SKA project and will provide the basis for future funding applications to secure German involvement in the Square Kilometre Array.Comment: Editors: H. R. Kl\"ockner, M. Kramer, H. Falcke, D.J. Schwarz, A. Eckart, G. Kauffmann, A. Zensus; 150 pages (low resolution- and colour-scale images), published in July 2012, language English (including a foreword and an executive summary in German), the original file is available via the MPIfR homepag

    Cold Nuclear Matter Effects on Dijet Productions in Relativistic Heavy-ion Reactions at LHC

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    We investigate the cold nuclear matter(CNM) effects on dijet productions in high-energy nuclear collisions at LHC with the next-to-leading order perturbative QCD. The nuclear modifications for dijet angular distributions, dijet invariant mass spectra, dijet transverse momentum spectra and dijet momentum imbalance due to CNM effects are calculated by incorporating EPS, EKS, HKN and DS param-etrization sets of parton distributions in nucleus . It is found that dijet angular distributions and dijet momentum imbalance are insensitive to the initial-state CNM effects and thus provide optimal tools to study the final-state hot QGP effects such as jet quenching. On the other hand, the invariant mass spectra and the transverse momentum spectra of dijet are generally enhanced in a wide region of the invariant mass or transverse momentum due to CNM effects with a feature opposite to the expected suppression because of the final-state parton energy loss effect in the QGP. The difference of EPS, EKS, HKN and DS parametrization sets of nuclear parton distribution functions is appreciable for dijet invariant mass spectra and transverse momentum spectra at p+Pb collisions, and becomes more pronounced for those at Pb+Pb reactions.Comment: 10 pages, 11 figure

    A Generalized Fluctuation-Dissipation Theorem for Nonlinear Response Functions

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    A nonlinear generalization of the Fluctuation-Dissipation Theorem (FDT) for the n-point Green functions and the amputated 1PI vertex functions at finite temperature is derived in the framework of the Closed Time Path formalism. We verify that this generalized FDT coincides with known results for n=2 and 3. New explicit relations among the 4-point nonlinear response and correlation (fluctuation) functions are presented.Comment: 34 pages, Revte

    Spallation Neutron Production by 0.8, 1.2 and 1.6 GeV Protons on various Targets

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    Spallation neutron production in proton induced reactions on Al, Fe, Zr, W, Pb and Th targets at 1.2 GeV and on Fe and Pb at 0.8, and 1.6 GeV measured at the SATURNE accelerator in Saclay is reported. The experimental double-differential cross-sections are compared with calculations performed with different intra-nuclear cascade models implemented in high energy transport codes. The broad angular coverage also allowed the determination of average neutron multiplicities above 2 MeV. Deficiencies in some of the models commonly used for applications are pointed out.Comment: 20 pages, 32 figures, revised version, accepted fpr publication in Phys. Rev.
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