310 research outputs found

    Lobate Lac Scale (Paratachardina pseudolobata Kondo and Gullan) Invades from Oahu into Neighbor Islands: Statewide Survey in Hawaii

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    In Hawaii, lobate lac scale was rst detected on weeping banyan on Oahu in 2012. Since then, we have con rmed that lobate lac scale infests over 110 plant species in Hawaii, mainly ornamental and landscape plants in urban areas. The major impacts on host plants are dieback of twigs and branches, thinning of foliage, and death of the entire plant in some species. Given the frequency of in- terisland transportation of goods and people, it is likely that lobate lac scale spread to neighbor islands since its discovery on Oahu. We started this survey in January 2016 covering all major neighbor islands in Hawaii: Hawaii, Maui, Kauai, Molokai, and Lanai. Lobate lac scale was detected in Kona in May 2016, the rst con rmed incidence of this pest on a neighbor island outside of Oahu. Lobate lac scale was detected in Lihue in January 2017, the rst con rmed incidence of this pest on Kauai. With contribution from Hawaii Department of Agriculture, lobate lac scale was detected on Maui in May 2016. No lobate lac scale was detected on Molokai and Lanai in our survey. Inter-island shipping of nursery plants was considered the key route for the spread of lobate lac scale from Oahu to neighbor islands

    Caspase Activation Is Required for T Cell Proliferation

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    Triggering of Fas (CD95) by its ligand (FasL) rapidly induces cell death via recruitment of the adaptor protein Fas-associated death domain (FADD), resulting in activation of a caspase cascade. It was thus surprising that T lymphocytes deficient in FADD were reported recently to be not only resistant to FasL-mediated apoptosis, but also defective in their proliferative capacity. This finding suggested potentially dual roles of cell growth and death for Fas and possibly other death receptors. We report here that CD3-induced proliferation and interleukin 2 production by human T cells are blocked by inhibitors of caspase activity. This is paralleled by rapid cleavage of caspase-8 after CD3 stimulation, but no detectable processing of caspase-3 during the same interval. The caspase contribution to T cell activation may occur via TCR-mediated upregulation of FasL, as Fas-Fc blocked T cell proliferation, whereas soluble FasL augmented CD3-induced proliferation. These findings extend the role of death receptors to the promotion of T cell growth in a caspase-dependent manner

    Electronic Specific Heat of La_{2-x}Sr_{x}CuO_{4}: Pseudogap Formation and Reduction of the Superconducting Condensation Energy

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    To examine the so-called small pseudogap and the superconducting (SC) condensation energy U(0), the electronic specific heat Cel was measured on La_{2-x}Sr_{x}CuO_{4} up to ~120K. In samples with doping level p (=x) less than ~0.2, small pseudogap behavior appears in the \gamma (=Cel/T) vs. T curve around the mean-field critical temperature for a d-wave superconductor Tco (=2*\Delta_{0}/(4~5)k_B), where \Delta_{0} is the maximum gap at T<<Tc. The condensation energy U(0) is largely reduced in the pseudogap regime (p< ~0.2). The reduction of U(0) can be well reproduced by introducing an effective SC energy scale \Delta_{eff}=\beta*p*\Delta_{0} (\beta=4.5) instead of \Delta_{0}. The effective SC energy scale is discussed in relation to the coherent pairing gap formed over the nodal Fermi arc.Comment: 8page

    Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm

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    The PHENIX experiement has measured the electron-positron pair mass spectrum from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions from light meson decays to e^+e^- pairs have been determined based on measurements of hadron production cross sections by PHENIX. They account for nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair yield remaining after subtracting these contributions is dominated by semileptonic decays of charmed hadrons correlated through flavor conservation. Using the spectral shape predicted by PYTHIA, we estimate the charm production cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which is consistent with QCD calculations and measurements of single leptons by PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables. Submitted to Physics Letters B. v2 fixes technical errors in matching authors to institutions. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Inclusive cross section and double helicity asymmetry for \pi^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton

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    The PHENIX experiment presents results from the RHIC 2005 run with polarized proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at mid-rapidity. Unpolarized cross section results are given for transverse momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both lower and higher p_T. The cross section is described well for p_T < 1 GeV/c by an exponential in p_T, and, for p_T > 2 GeV/c, by perturbative QCD. Double helicity asymmetries A_LL are presented based on a factor of five improvement in uncertainties as compared to previously published results, due to both an improved beam polarization of 50%, and to higher integrated luminosity. These measurements are sensitive to the gluon polarization in the proton, and exclude maximal values for the gluon polarization.Comment: 375 authors, 7 pages, 3 figures. Submitted to Phys. Rev. D, Rapid Communications. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    System Size and Energy Dependence of Jet-Induced Hadron Pair Correlation Shapes in Cu+Cu and Au+Au Collisions at sqrt(s_NN) = 200 and 62.4 GeV

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    We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from {dijets} in Cu+Cu and Au+Au collisions at sqrt(s_NN) = 62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from \Delta\phi=\pi in central and semi-central collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.Comment: 464 authors from 60 institutions, 6 pages, 3 figures, 2 tables. Submitted to Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Measurement of high-p_T Single Electrons from Heavy-Flavor Decays in p+p Collisions at sqrt(s) = 200 GeV

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    The momentum distribution of electrons from decays of heavy flavor (charm and beauty) for midrapidity |y| < 0.35 in p+p collisions at sqrt(s) = 200 GeV has been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider (RHIC) over the transverse momentum range 0.3 < p_T < 9 GeV/c. Two independent methods have been used to determine the heavy flavor yields, and the results are in good agreement with each other. A fixed-order-plus-next-to-leading-log pQCD calculation agrees with the data within the theoretical and experimental uncertainties, with the data/theory ratio of 1.72 +/- 0.02^stat +/- 0.19^sys for 0.3 < p_T < 9 GeV/c. The total charm production cross section at this energy has also been deduced to be sigma_(c c^bar) = 567 +/- 57^stat +/- 224^sys micro barns.Comment: 375 authors from 57 institutions, 6 pages, 3 figures. Submitted to Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    High-pT pi^zero Production with Respect to the Reaction Plane in Au + Au Collisions at sqrt(s_NN) = 200 GeV

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    Measurements of the azimuthal anisotropy of high-\pT neutral pion neutral pion production in Au+Au collisions at sqrt(s_NN) = 200 GeV by the PHENIX experiment are presented. The data included in this paper were collected during the 2004 RHIC running period and represent approximately an order of magnitude increase in the number of analyzed events relative to previously published results. Azimuthal angle distributions of pi^0s detected in the PHENIX electromagnetic calorimeters are measured relative to the reaction plane determined event-by-event using the forward and backward beam-beam counters. Amplitudes of the second Fourier component (v_2) of the angular distributions are presented as a function of pi^0 transverse momentum p_T for different bins in collision centrality. Measured reaction plane dependent pi^0 yields are used to determine the azimuthal dependence of the pi^0 suppression as a function of p_T, R_AA (Delta phi,p_T). A jet-quenching motivated geometric analysis is presented that attempts to simultaneously describe the centrality dependence and reaction plane angle dependence of the pi^0 suppression in terms of the path lengths of hypothetical parent partons in the medium. This set of results allows for a detailed examination of the influence of geometry in the collision region, and of the interplay between collective flow and jet-quenching effects along the azimuthal axis.Comment: 344 authors, 35 pages text, RevTeX-4, 24 figures, 8 tables. Submitted to Physical Review

    Transverse-energy distributions at midrapidity in pp++pp, dd++Au, and Au++Au collisions at sNN=62.4\sqrt{s_{_{NN}}}=62.4--200~GeV and implications for particle-production models

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    Measurements of the midrapidity transverse energy distribution, d\Et/d\eta, are presented for pp++pp, dd++Au, and Au++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV and additionally for Au++Au collisions at sNN=62.4\sqrt{s_{_{NN}}}=62.4 and 130 GeV. The d\Et/d\eta distributions are first compared with the number of nucleon participants NpartN_{\rm part}, number of binary collisions NcollN_{\rm coll}, and number of constituent-quark participants NqpN_{qp} calculated from a Glauber model based on the nuclear geometry. For Au++Au, \mean{d\Et/d\eta}/N_{\rm part} increases with NpartN_{\rm part}, while \mean{d\Et/d\eta}/N_{qp} is approximately constant for all three energies. This indicates that the two component ansatz, dET/dη(1x)Npart/2+xNcolldE_{T}/d\eta \propto (1-x) N_{\rm part}/2 + x N_{\rm coll}, which has been used to represent ETE_T distributions, is simply a proxy for NqpN_{qp}, and that the NcollN_{\rm coll} term does not represent a hard-scattering component in ETE_T distributions. The dET/dηdE_{T}/d\eta distributions of Au++Au and dd++Au are then calculated from the measured pp++pp ETE_T distribution using two models that both reproduce the Au++Au data. However, while the number-of-constituent-quark-participant model agrees well with the dd++Au data, the additive-quark model does not.Comment: 391 authors, 24 pages, 19 figures, and 15 Tables. Submitted to Phys. Rev. C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are publicly available at http://www.phenix.bnl.gov/papers.htm
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