685 research outputs found

    Effect of Diet on Mortality and Larval Duration in Chrysodeixis includens (Lepidoptera: Noctuidae)

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    Diet mediates many life history trade-offs and therefore is an important environmental component to consider. Because some organisms share food sources with humans, they encounter anthropogenic changes to their diet, such as genetically modified crops and chemical applications, which can contribute to additional complexity in their environment. To understand the effect of diet on the life history of the soybean looper, Chrysodeixis includens, we exposed larvae to several different food sources, including genetically modified soybean leaves and the pesticide spinosad. Significant differences in larval instar duration and timing of larval mortality among treatments were observed indicating that type of diet has complex effects on the life history of C. includens

    MesonNet 2013 International Workshop. Mini-proceedings

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    The mini-proceedings of the MesonNet 2013 International Workshop held in Prague from June 17th to 19th, 2013, are presented. MesonNet is a research network within EU HadronPhysics3 project (1/2012 -- 12/2014). The web page of the conference, which contains all talks, can be found at http://ipnp.mff.cuni.cz/mesonnet13Comment: 106 pages, 53 contributions. Mini-proceedings of the MesonNet 2013 International Workshop. Editors: K. Kampf, A. Kupsc, and P. Masjua

    Origin of the low-mass electron pair excess in light nucleus-nucleus collisions

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    We report measurements of electron pair production in elementary p+p and d+p reactions at 1.25 GeV/u with the HADES spectrometer. For the first time, the electron pairs were reconstructed for n+p reactions by detecting the proton spectator from the deuteron breakup. We find that the yield of electron pairs with invariant mass Me+e- > 0.15 GeV/c2 is about an order of magnitude larger in n+p reactions as compared to p+p. A comparison to model calculations demonstrates that the production mechanism is not sufficiently described yet. The electron pair spectra measured in C+C reactions are compatible with a superposition of elementary n+p and p+p collisions, leaving little room for additional electron pair sources in such light collision systems.Comment: 11 pages, 2 figures, \usepackage{epsfig

    Production of Sigma{\pm}pi?pK+ in p+p reactions at 3.5 GeV beam energy

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    We study the production of Sigma^+-pi^+-pK^+ particle quartets in p+p reactions at 3.5 GeV kinetic beam energy. The data were taken with the HADES experiment at GSI. This report evaluates the contribution of resonances like Lambda(1405$, Sigma(1385)^0, Lambda(1520), Delta(1232), N^* and K^*0 to the Sigma^+- pi^-+ p K+ final state. The resulting simulation model is compared to the experimental data in several angular distributions and it shows itself as suitable to evaluate the acceptance corrections properly.Comment: 15 pages, 5 figure

    An upper limit on hypertriton production in collisions of Ar(1.76 AGeV)+KCl

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    A high-statistic data sample of Ar(1.76 AGeV)+KCl events recorded with HADES is used to search for a hypertriton signal. An upper production limit per centrality-triggered event of 1.041.04 x 10310^{-3} on the 3σ3\sigma level is derived. Comparing this value with the number of successfully reconstructed Λ\Lambda hyperons allows to determine an upper limit on the ratio NΛ3H/NΛN_{_{\Lambda}^3H}/N_{\Lambda}, which is confronted with statistical and coalescence-type model calculations

    In-Medium Effects on K0 Mesons in Relativistic Heavy-Ion Collisions

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    We present the transverse momentum spectra and rapidity distributions of π\pi^{-} and KS0^0_S in Ar+KCl reactions at a beam kinetic energy of 1.756 A GeV measured with the spectrometer HADES. The reconstructed KS0^0_S sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental π\pi^{-} and KS0^0_S distributions to predictions by the IQMD model. The model calculations show that KS0^0_S at low tranverse momenta constitute a particularly well suited tool to investigate the kaon in-medium potential. Our KS0^0_S data suggest a strong repulsive in-medium K0^0 potential of about 40 MeV strength.Comment: 10 pages, 10 figures, accepted by Phys. Rev.

    The Λp\bf{\Lambda p} interaction studied via femtoscopy in p + Nb reactions at sNN=3.18 GeV\mathbf{\sqrt{s_{NN}}=3.18} ~\mathrm{\bf{GeV}}

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    We report on the first measurement of pΛp\Lambda and pppp correlations via the femtoscopy method in p+Nb reactions at sNN=3.18 GeV\mathrm{\sqrt{s_{NN}}=3.18} ~\mathrm{GeV}, studied with the High Acceptance Di-Electron Spectrometer (HADES). By comparing the experimental correlation function to model calculations, a source size for pppp pairs of r0,pp=2.02±0.01(stat)0.12+0.11(sys) fmr_{0,pp}=2.02 \pm 0.01(\mathrm{stat})^{+0.11}_{-0.12} (\mathrm{sys}) ~\mathrm{fm} and a slightly smaller value for pΛp\Lambda of r0,Λp=1.62±0.02(stat)0.08+0.19(sys) fmr_{0,\Lambda p}=1.62 \pm 0.02(\mathrm{stat})^{+0.19}_{-0.08}(\mathrm{sys}) ~\mathrm{fm} is extracted. Using the geometrical extent of the particle emitting region, determined experimentally with pppp correlations as reference together with a source function from a transport model, it is possible to study different sets of scattering parameters. The pΛp\Lambda correlation is proven sensitive to predicted scattering length values from chiral effective field theory. We demonstrate that the femtoscopy technique can be used as valid alternative to the analysis of scattering data to study the hyperon-nucleon interaction.Comment: 12 pages, 11 figure

    Baryonic resonances close to the Kbar-N threshold: the case of Sigma(1385)^+ in pp collisions

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    We present results of an exclusive measurement of the first excited state of the Sigma hyperon, Sigma(1385)^+, produced in p+p -> Sigma^+ + K^+ + n at 3.5 GeV beam energy. The extracted data allow to study in detail the invariant mass distribution of the Sigma(1385)^+. The mass distribution is well described by a relativistic Breit-Wigner function with a maximum at m_0 = 1383.2 +- 0.9 MeV/c^2 and a width of 40.2 +- 2.1 MeV/c^2. The exclusive production cross-section comes out to be 22.27 +- 0.89 +- 1.56 +3.07 -2.10 mu b. Angular distributions of the Sigma(1385)^+ in different reference frames are found to be compatible with the hypothesis that 33 % of Sigma(1385)^+ result from the decay of an intermediate Delta^{++} resonance.Comment: 12 pages; 12 figures; submitted to PR
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