8,894 research outputs found

    Charge-dependent anisotropic flow studies and the search for the Chiral Magnetic Wave in ALICE

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    Theoretical calculations have shown the possibility of P-violating bubbles in the QCD vacuum, which in combination with the strong magnetic field created in off-central heavy-ion collisions lead to novel effects such as the Chiral Magnetic Effect (CME) and the Chiral Separation Effect (CSE). A coupling between the CME and the CSE produces a wave-like excitation called the Chiral Magnetic Wave (CMW). The CMW produces a quadrupole moment that always has the same sign and is therefore present in an average over events. In this talk we present a series of charge-dependent anisotropic flow measurements in Pb--Pb collisions at sNN\sqrt{s_{NN}} = 2.76 TeV in ALICE, using two- and three-particle correlators with unidentified hadrons. The relation of these measurements to the search for the CMW is discussed.Comment: 4 pages, 4 figures, Proceedings of XXIV International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2014), May 19-24, 2014, Darmstad

    Teflon-packed flexible joint

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    Teflon-packed flexible joint separates the movement of the shaker from the liquid nitrogen hose during the ground testing of cryogenic zero-g equipment. The joint allows the hose to lie on the floor in a stationary position as the shaker moves back and forth, thus, the hose is not subject to violent motion

    Does Active Management Benefit Endowment Returns?

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    We conduct a longitudinal analysis of the NACUBO Commonfund Study of Endowments (NCSE) results from 2006-2013 to evaluate if active management is related to higher endowment returns in U.S. equities over time. We also analyze the data to evaluate the endowment characteristics that are related to higher levels of performance over time.We find that active management for endowments is significantly positively related to higher returns net of fees from U.S. equity allocations over the evaluation period. In addition, endowments with CIOs or OCIOs are better able to earn incremental positive returns from active management than those without. Larger endowments are better able to earn incremental positive returns from active management than the smallest endowments but the effect appears to diminish as endowments increase in size

    Ozone Contamination in Aircraft Cabins. Appendix B: Overview papers. Flight 8 planning to avoid high ozone

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    The problem of preventing cabin ozone from exceeding a given standard was investigated. Statistical analysis of vertical distribution of ozone is summarized. The cost, logistics, maintenance, ability to forecast ozone, and avoiding high ozone concentrations are presented. Filtering approaches and the requirements to remove ozone toxicity are discussed

    New insight into short wavelength solar wind fluctuations from Vlasov theory

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    The nature of solar wind (SW) turbulence below the proton gyroscale is a topic that is being investigated extensively nowadays. Although recent observations gave evidence of the dominance of Kinetic Alfv\'en Waves (KAW) at sub-ion scales with ω<ωci\omega<{\omega_{ci}}, other studies suggest that the KAW mode cannot carry the turbulence cascade down to electron scales and that the whistler mode (i.e., ω>ωci\omega>\omega_{ci}) is more relevant. Here, we propose to study key properties of the short wavelength plasma modes under realistic SW conditions, typically βiβe1\beta_i\gtrsim \beta_e\sim 1 and for high oblique angles of propagation 80ΘkB<9080^\circ\leq \Theta_{\bf kB}<90^\circ as observed from the Cluster data. The linear properties of the plasma modes under these conditions are poorly known, which contrasts with the well-documented cold plasma limit and/or moderate oblique angles of propagation (ΘkB<80\Theta_{\bf kB} <80^\circ). Based on linear solutions of the Vlasov kinetic theory, we discuss the relevance of each plasma mode (fast, Bernstein, KAW, whistler) in carrying the energy cascade down to electron scales. We show, in particular, that the shear Alfv\'en mode extends at scales kρi1k\rho_i\gtrsim1 following either a whistler mode (ω>ωci\omega>\omega_{ci}) or a KAW mode (with ω<ωci\omega<\omega_{ci}) depending on the anisotropy k/kk_\parallel/ k_\perp. This contrasts with the well-accepted idea that the whistler branch develops as a continuation at high frequencies of the fast magnetosonic mode. We show, furthermore, that the whistler branch is more damped than the KAW one, which makes the latter a more relevant candidate to carry the energy cascade down to electron scales. We discuss how these new findings may facilitate resolution of the controversy concerning the nature of the small scale turbulence, and we discuss the implications for present and future spacecraft wave measurements in the SW.Comment: 11 pages, 12 figures, submitted to Astrophysical Journa

    Radiation processes around accreting black holes

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    Accreting sources such as AGN, X-ray binaries or gamma-ray bursts are known to be strong, high energy emitters. The hard emission is though to originate from plasmas of thermal and/or non-thermal high energy particles. Not only does this emission allow to probe the unique properties of the matter in an extreme environment, but it also has a crucial backreaction on the energetics and the dynamics of the emitting medium itself. Understanding interactions between radiation and matter has become a key issue in the modelling of high energy sources. Although most cross sections are well known, they are quite complex and the way all processes couple non-linearly is still an open issue. We present a new code that solves the local, kinetic evolution equations for distributions of electrons, positrons and photons, interacting by radiation processes such as self-absorbed synchrotron and brems-strahlung radiation, Compton scattering, pair production/annihilation, and by Coulomb collisions. The code is very general and aimed to modelled various high energy sources. As an application, we study the spectral states of X-ray binaries, including thermalization by Coulomb collisions and synchrotron self-absorption. It is found that the low-hard and high-soft states can be modelled with different illumination but the same non-thermal acceleration mechanism.Comment: 4 pages, 2 figures, proceedings of the SF2A conference 200

    Energy Loss and Flavor Dynamics from Single Particle Measurements in PHENIX

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    The transverse momentum spectra, yields, and ratios of charged pions, protons, and antiprotons have been studied up to 5 GeV/c in pTp_T in 5 different centrality classes in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV. These results are compared and contrasted with the observables calculated in recombination models of hadronization. They are also used to examine the color charge dependence of parton energy loss in the medium.Comment: 4 pages, 6 figures, to appear in the Proceedings of Quark Matter 200

    The x-ray corona and jet of cygnus x-1

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    Evidence is presented indicating that in the hard state of Cygnus X-1, the coronal mag- netic field might be below equipartition with radiation (suggesting that the corona is not powered by magnetic field dissipation) and that the ion temperature in the corona is significantly lower than what predicted by ADAF like models. It is also shown that the current estimates of the jet power set interesting contraints on the jet velocity (which is at least mildly relativistic), the accretion efficiency (which is large in both spectral states), and the nature of the X-ray emitting region (which is unlikely to be the jet).Comment: 8 pages, 1 figure. Accepted for publication in Journal of Modern Physics D, Proceedings of HEPRO II conference, Buenos Aires, Argentina, October 26-30, 200
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