319 research outputs found

    Cooperative Evaluation of Inner Mongolia, PRC, Grassland Germplasm in the Western USA

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    Replicated dryland studies were established at three USDA, NRCS, Plant Materials Centers in the USA northern intermountain west by Chinese and American scientists. Forty-six Asian and 16 USA grasses, legumes, and shrubs were included. These plantings were evaluated for vigor, percent stand, and foliage height in 1994 and 1995, and for biomass production in 1995. Generally, USA grasses outperformed Asian grasses, while Inner Mongolian legumes show the highest potential for use in the intermountain west

    Lack of Rbl1/p107 Effects on Cell Proliferation and Maturation in the Inner Ear

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    Loss of postnatal mammalian auditory hair cells (HCs) is irreversible. Earlier studies have highlighted the importance of the Retinoblastoma family of proteins (pRBs) (i.e., Rb1, Rbl1/p107, and Rbl2/p130) in the auditory cells’ proliferation and emphasized our lack of information on their specific roles in the auditory system. We have previously demonstrated that lack of Rbl2/p130 moderately affects HCs’ and supporting cells’ (SCs) proliferation. Here, we present evidence supporting multiple roles for Rbl1/p107 in the developing and mature mouse organ of Corti (OC). Like other pRBs, Rbl1/p107 is expressed in the OC, particularly in the Hensen’s and Deiters’ cells. Moreover, Rbl1/p107 impacts maturation and postmitotic quiescence of HCs and SCs, as evidenced by enhanced numbers of these cells and the presence of dividing cells in the postnatal Rbl1/p107−/− OC. These findings were further supported by microarray and bioinformatics analyses, suggesting downregulation of several bHLH molecules, as well as activation of the Notch/Hes/Hey signaling pathway in homozygous Rbl1/p107 mutant mice. Physiological assessments and detection of ectopic HC marker expression in postnatal spiral ganglion neurons (SGNs) provided evidence for incomplete cell maturation and differentiation in Rbl1/p107−/− OC. Collectively, the present study highlights an important role for Rbl1/p107 in OC cell differentiation and maturation, which is distinct from other pRBs

    Group descent algorithms for nonconvex penalized linear and logistic regression models with grouped predictors

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    Penalized regression is an attractive framework for variable selection problems. Often, variables possess a grouping structure, and the relevant selection problem is that of selecting groups, not individual variables. The group lasso has been proposed as a way of extending the ideas of the lasso to the problem of group selection. Nonconvex penalties such as SCAD and MCP have been proposed and shown to have several advantages over the lasso; these penalties may also be extended to the group selection problem, giving rise to group SCAD and group MCP methods. Here, we describe algorithms for fitting these models stably and efficiently. In addition, we present simulation results and real data examples comparing and contrasting the statistical properties of these methods

    Centrality dependence of charged-particle pseudorapidity distributions from d+Au collisions at sqrt(s_{NN})=200 GeV

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    Charged-particle pseudorapidity densities are presented for the d+Au reaction at sqrt{s_{NN}}=200 GeV with -4.2 <= eta <= 4.2$. The results, from the BRAHMS experiment at RHIC, are shown for minimum-bias events and 0-30%, 30-60%, and 60-80% centrality classes. Models incorporating both soft physics and hard, perturbative QCD-based scattering physics agree well with the experimental results. The data do not support predictions based on strong-coupling, semi-classical QCD. In the deuteron-fragmentation region the central 200 GeV data show behavior similar to full-overlap d+Au results at sqrt{s_{NN}}=19.4 GeV.Comment: 4 pages, 3figures; expanded discussion of uncertainties; added 60-80% centrality range; added additional discussion on centrality selection bia

    Scanning the phases of QCD with BRAHMS

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    BRAHMS has the ability to study relativistic heavy ion collisions from the final freeze-out of hadrons all the way back to the initial wave-function of the gold nuclei. This is accomplished by studying hadrons with a very wide range of momenta and angles. In doing so we can scan various phases of QCD, from a hadron gas, to a quark gluon plasma and perhaps to a color glass condensate.Comment: 8 pages, 6 figures, proceedings of plenary talk at Quark Matter 2004 conferenc

    High Pt Hadron Spectra at High Rapidity

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    We report the measurement of charged hadron production at different pseudo-rapidity values in deuteron+gold as well as proton+proton collisions at sqrtsNNsqrt{s_{NN}} = 200GeV at RHIC. The nuclear modification factors RdAuR_{dAu} and RcpR_{cp} are used to investigate new behaviors in the deuteron+gold system as function of rapidity and the centrality of the collisions respectively.Comment: Nine pages 4 figures to be published in the QM2004 Proceedings, typos corrected and one reference adde

    Evolution of the nuclear modification factors with rapidity and centrality in d+Au collisions at $\sqrt{s_{NN}} = 200 GeV

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    We report on a study of the transverse momentum dependence of nuclear modification factors RdAuR_{dAu} for charged hadrons produced in deuteron + gold collisions at sNN=200\sqrt{s_{NN}}= 200GeV, as a function of collision centrality and of the pseudorapidity (η=0,1,2.2,3.2\eta = 0,1,2.2,3.2) of the produced hadrons. We find significant and systematic decrease of RdAuR_{dAu} with increasing rapidity. The midrapidity enhancement and the forward rapidity suppression are more pronounced in central collisions relative to peripheral collisions. These results are relevant to the study of the possible onset of gluon saturation at RHIC energies.Comment: Four pages, four figures. Published in PRL. Figures 1 and 2 have been updated, and several changes made to the tex

    Nuclear Stopping in Au+Au Collisions at sqrt(sNN) = 200 GeV

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    Transverse momentum spectra and rapidity densities, dN/dy, of protons, anti-protons, and net--protons (p-pbar) from central (0-5%) Au+Au collisions at sqrt(sNN) = 200 GeV were measured with the BRAHMS experiment within the rapidity range 0 < y < 3. The proton and anti-proton dN/dy decrease from mid-rapidity to y=3. The net-proton yield is roughly constant for y<1 at dN/dy~7, and increases to dN/dy~12 at y~3. The data show that collisions at this energy exhibit a high degree of transparency and that the linear scaling of rapidity loss with rapidity observed at lower energies is broken. The energy loss per participant nucleon is estimated to be 73 +- 6 GeV.Comment: 5 pages, 4 figure

    Quark Gluon Plasma an Color Glass Condensate at RHIC? The perspective from the BRAHMS experiment

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    We review the main results obtained by the BRAHMS collaboration on the properties of hot and dense hadronic and partonic matter produced in ultrarelativistic heavy ion collisions at RHIC. A particular focus of this paper is to discuss to what extent the results collected so far by BRAHMS, and by the other three experiments at RHIC, can be taken as evidence for the formation of a state of deconfined partonic matter, the so called quark-gluon-plasma (QGP). We also discuss evidence for a possible precursor state to the QGP, i.e. the proposed Color Glass Condensate.Comment: 32 pages, 18 figure
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