21 research outputs found

    Selection of strawberry cultivars with tolerance to Tetranychus urticae (Acari: Tetranychidae) and high yield under different managements.

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    Tetranychus urticae Koch (Acari: Tetranychidae) is considered the main pest of strawberry. Several factors can favor its development, among them the genotype susceptibility and cropping system. The aims of this study were to evaluate the agronomic performance of strawberry cultivars under different managements and to identify strawberry cultivars that meet tolerance to T. urticae and high fruit yield. Thirteen cultivars of strawberry ('Albion', 'Aleluia', 'Aromas', 'Camarosa', 'Camino Real', 'Campinas', 'Diamante', 'Dover', 'Festival', 'Seascape', 'Toyonoka', 'Tudla', and 'Ventana') under three managements (open field, low tunnel, and high tunnel) were evaluated. The T. urticae attack to different cultivars was influenced by managements, being low tunnel the one that provided higher infestations in the most evaluated cultivars. 'Camarosa' was the cultivar with the lower incidence of pest and 'Dover' had the higher infestation. The genotype most suitable for growing under different managements is the 'Festival' genotype, since it meets tolerance to T. urticae, high fruit yield, and phenotypic stability

    Identified hadron spectra at large transverse momentum in p+p and d+Au collisions at √sNN = 200 GeV

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    We present the transverse momentum (pT) spectra for identified charged pions, protons and anti-protons from p+p and d+Au collisions at . The spectra are measured around midrapidity (|y|/c with particle identification from the ionization energy loss and its relativistic rise in the time projection chamber and time-of-flight in STAR. The charged pion and proton + anti-proton spectra at high pT in p+p and d+Au collisions are in good agreement with a phenomenological model (EPOS) and with next-to-leading order perturbative quantum chromodynamic (NLO pQCD) calculations with a specific fragmentation scheme and factorization scale. We found that all proton, anti-proton and charged pion spectra in p+p collisions follow xT-scaling for the momentum range where particle production is dominated by hard processes (pT≳2 GeV/c). The nuclear modification factor around midrapidity is found to be greater than unity for charged pions and to be even larger for protons at 2T/c

    Proton-Λ correlations in central Au+Au collisions at √s\u3csub\u3eNN\u3c/sub\u3e = 200 GeV

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    We report on p−Λ,p− ¯Λ¯ ,¯p¯−Λ, and ¯p¯− ¯Λ¯ correlation functions constructed in central Au-Au collisions at √sNN=200 GeV by the STAR experiment at RHIC. The proton and lambda source size is inferred from the p−Λ and p− ¯Λ¯; correlation functions. It is found to be smaller than the pion source size also measured by the STAR experiment at smaller transverse masses, in agreement with a scenario of a strong universal collective flow. The ¯p¯− Λ and p− ¯Λ¯ correlation functions, which are measured for the first time, exhibit a large anticorrelation. Annihilation channels and/or a negative real part of the spin-averaged scattering length must be included in the final-state interactions calculation to reproduce the measured correlation function

    Energy dependence of charged pion, proton and anti-proton transverse momentum spectra for Au+Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV

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    We study the energy dependence of the transverse momentum (pT) spectra for charged pions, protons and anti-protons for Au+Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV. Data are presented at mid-rapidity (|y| < 0.5) for 0.2 < pT < 12 GeV/c. In the intermediate pT region (2 < pT < 6 GeV/c), the nuclear modification factor is higher at 62.4 GeV than at 200 GeV, while at higher pT (pT >7 GeV/c) the modification is similar for both energies. The p/pi+ and pbar/pi- ratios for central collisions at \sqrt{s_NN} = 62.4 GeV peak at pT ~ 2 GeV/c. In the pT range where recombination is expected to dominate, the p/pi+ ratios at 62.4 GeV are larger than at 200 GeV, while the pbar/pi- ratios are smaller. For pT > 2 GeV/c, the pbar/pi- ratios at the two beam energies are independent of pT and centrality indicating that the dependence of the pbar/pi- ratio on pT does not change between 62.4 and 200 GeV. These findings challenge various models incorporating jet quenching and/or constituent quark coalescence.Comment: 19 pages and 6 figure

    Transverse-momentum p\u3csub\u3et\u3c/sub\u3e correlations on (η,ϕ) from mean-p\u3csub\u3et\u3c/sub\u3e fluctuations in Au–Au collisions at √s\u3csub\u3eNN\u3c/sub\u3e = 200 GeV

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    We present first measurements of the pseudorapidity and azimuth (η, ϕ) binsize dependence of event-wise mean transverse-momentum ⟨pt⟩ fluctuations for Au–Au collisions at √sNN = 200 GeV. We invert that dependence to obtain pt autocorrelations on differences (η∆, ϕ∆) interpreted to represent velocity/temperature distributions on (η, ϕ). The general form of the autocorrelations suggests that the basic correlation mechanism is parton fragmentation. The autocorrelations vary rapidly with collision centrality, which suggests that fragmentation is strongly modified by a dissipative medium in the more central Au–Au collisions relative to peripheral or p–p collisions

    Hadronization geometry from net-charge angular correlations on momentum subspace (η,ϕ\eta,\phi) in Au-Au collisions at sNN=130\sqrt{s_{NN}} = 130 GeV

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    We present the first measurements of charge-dependent correlations on angular difference variables η1η2\eta_1 - \eta_2 (pseudorapidity) and ϕ1ϕ2\phi_1 - \phi_2 (azimuth) for primary charged hadrons with transverse momentum 0.15pt20.15 \leq p_t \leq 2 GeV/cc and η1.3|\eta| \leq 1.3 from Au-Au collisions at sNN=130\sqrt{s_{NN}} = 130 GeV. We observe correlation structures not predicted by theory but consistent with evolution of hadron emission geometry with increasing centrality from one-dimensional fragmentation of color strings along the beam direction to an at least two-dimensional hadronization geometry along the beam and azimuth directions of a hadron-opaque bulk medium.Comment: 8 pages, 4 figure

    Forward Neutral Pion Production in p + p and d + Au Collisions at √ sNN = 200 GeV

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    Measurements of the production of forward π0 mesons from p+p and d+Au collisions at √sNN=200  GeV are reported. The p+p yield generally agrees with next-to-leading order perturbative QCD calculations. The d+Au yield per binary collision is suppressed as η increases, decreasing to ∼30% of the p+p yield at ⟨η⟩=4.00, well below shadowing expectations. Exploratory measurements of azimuthal correlations of the forward π0 with charged hadrons at η≈0 show a recoil peak in p+p that is suppressed in d+Au at low pion energy. These observations are qualitatively consistent with a saturation picture of the low-x gluon structure of heavy nuclei

    Transverse-momentum ptp_t correlations on (η,ϕ)(\eta,\phi) from mean-ptp_{t} fluctuations in Au-Au collisions at sNN=\sqrt{s_{NN}} = 200 GeV

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    We present first measurements of the pseudorapidity and azimuth (η,ϕ)(\eta,\phi) bin-size dependence of event-wise mean transverse momentum fluctuations for Au-Au collisions at sNN=200\sqrt{s_{NN}} = 200 GeV. We invert that dependence to obtain ptp_t autocorrelations on differences (ηΔ,ϕΔ)(\eta_\Delta,\phi_\Delta) interpreted to represent velocity/temperature distributions on (η,ϕ\eta,\phi). The general form of the autocorrelations suggests that the basic correlation mechanism is parton fragmentation. The autocorrelations vary strongly with collision centrality, which suggests that fragmentation is strongly modified by a dissipative medium in the more central Au-Au collisions relative to peripheral or p-p collisions. \\Comment: 7 pages, 3 figure
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