20,713 research outputs found

    Understanding chemical evolution in resolved galaxies -- I The local star fraction-metallicity relation

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    This work studies the relation between gas-phase oxygen abundance and stellar-to-gas fraction in nearby galaxies. We first derive the theoretical prediction, and argue that this relation is fundamental, in the sense that it must be verified regardless of the details of the gas accretion and star formation histories. Moreover, it should hold on "local" scales, i.e. in regions of the order of 1 kpc. These predictions are then compared with a set of spectroscopic observations, including both integrated and resolved data. Although the results depend somewhat on the adopted metallicity calibration, observed galaxies are consistent with the predicted relation, imposing tight constraints on the mass-loading factor of (enriched) galactic winds. The proposed parametrization of the star fraction-metallicity relation is able to describe the observed dependence of the oxygen abundance on gas mass at fixed stellar mass. However, the "local" mass-metallicity relation also depends on the relation between stellar and gas surface densities.Comment: 10 pages, 4 figures. Matches accepted version (significant typo corrected

    The Importance of Asymptotic Freedom for the Pseudocritical Temperature in Magnetized Quark Matter

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    Although asymptotic freedom is an essential feature of QCD, it is absent in effective chiral quark models like the Nambu--Jona-Lasinio and linear sigma models. In this work we advocate that asymptotic freedom plays a key role in the recently observed discrepancies between results of lattice QCD simulations and quark models regarding the behavior of the pseudocritical temperature TpcT_{\rm pc} for chiral symmetry restoration in the presence of a magnetic field BB. We show that the lattice predictions that TpcT_{\rm pc} decreases with BB can be reproduced within the Nambu--Jona-Lasinio model if the coupling constant GG of the model decreases with BB and the temperature. Without aiming at numerical precision, we support our claim by considering a simple ansatz for GG that mimics the asymptotic freedom behavior of the QCD coupling constant 1/αsln(eB/ΛQCD2)1/\alpha_s \sim \ln (eB/\Lambda^2_{QCD}) for large values of BB.Comment: 5 pages, 4 figures. This version matches the published on

    Development of casein micellar pediatric formulations

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    Poster presented at the 1st European Conference on Pharmaceutics. 13-14 April 2015, Reims, France."The current need for medicines specifically designed for children, which consider ease of administration, dose flexibility, palatability, safety of excipients, stability and therapeutic equivalency of pediatric dosage forms, has driven the development of pediatric drug formulations. In the present work casein (CN) based micellar formulations are evaluated as vehicles for the oral delivery of pediatric drugs, since caseins are nontoxic, biodegradable, GRAS materials and nanoencapsulation of drugs can improve their bioavailability. Chemical crosslinking of casein by carbodiimide (EDC) has been studied as an approach to improve the stability of the CN micelles and to tailor drug release."Fundação para a Ciência e a Tecnologia, Portugal (Research grant PTDC/DTPFTO/1057/2012

    Tanaka-Tagoshi Parametrization of post-1PN Spin-Free Gravitational Wave Chirps: Equispaced and Cardinal Interpolated Lattices For First Generation Interferometric Antennas

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    The spin-free binary-inspiral parameter-space introduced by Tanaka and Tagoshi to construct a uniformly-spaced lattice of templates at (and possibly beyond) 2.5PN2.5PN order is shown to work for all first generation interferometric gravitational wave antennas. This allows to extend the minimum-redundant cardinal interpolation techniques of the correlator bank developed by the Authors to the highest available order PN templates. The total number of 2PN templates to be computed for a minimal match Γ=0.97\Gamma=0.97 is reduced by a factor 4, as in the 1PN case.Comment: 9 pages, 8 figures, 3 tables, accepted for publication in Phys. Rev.

    Rejection Properties of Stochastic-Resonance-Based Detectors of Weak Harmonic Signals

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    In (V. Galdi et al., Phys. Rev. E57, 6470, 1998) a thorough characterization in terms of receiver operating characteristics (ROCs) of stochastic-resonance (SR) detectors of weak harmonic signals of known frequency in additive gaussian noise was given. It was shown that strobed sign-counting based strategies can be used to achieve a nice trade-off between performance and cost, by comparison with non-coherent correlators. Here we discuss the more realistic case where besides the sought signal (whose frequency is assumed known) further unwanted spectrally nearby signals with comparable amplitude are present. Rejection properties are discussed in terms of suitably defined false-alarm and false-dismissal probabilities for various values of interfering signal(s) strength and spectral separation.Comment: 4 pages, 5 figures. Misprints corrected. PACS numbers added. RevTeX

    Thermodynamics and Phase Structure of the Two-Flavor Nambu--Jona-Lasinio Model Beyond Large-N_c

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    The optimized perturbation theory (OPT) method is applied to the SU(2)SU(2) version of the Nambu--Jona-Lasinio (NJL) model both at zero and at finite temperature and/or density. At the first nontrivial order the OPT exhibits a class of 1/N_c corrections which produce nonperturbative results that go beyond the standard large-N_c, or mean-field approximation. The consistency of the OPT method with the Goldstone theorem at this order is established, and appropriate OPT values of the basic NJL (vacuum) parameters are obtained by matching the pion mass and decay constant consistently. Deviations from standard large-N_c relations induced by OPT at this order are derived, for example, for the Gell--Mann-Oakes-Renner relation. Next, the results for the critical quantities and the phase diagram of the model, as well as a number of other thermodynamical quantities of interest, are obtained with OPT and then contrasted with the corresponding results at large N_c.Comment: 29 pages, 20 figures, revtex. Minor corrections. In press Phys. Rev.

    A new species of killifish (Pisces, Cyprinodontidae) from the chilean Altiplano

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    Ce travail décrit #Orestia chungarensis n. sp., un poisson Cyprinodontidae du lac Chungara (Altiplano chilien). #O. chungarensis n. sp. est élancé à flancs gris et ventre blanc avec des bandes verticales marron sombre. Il est caractérisé par ses grands yeux, sa bouche petite et protactile, ses mandibules dirigées vers le haut et ses nageoires pectorales petites comportant peu de rayons. Il vit dans les herbiers de #Myriophyllumelatinoides des zones littorales peu profondes de la partie ouest du lac. Il se nourrit principalement d'Amphipodes et de Chironomidae. Par ses caractéristiques morphologiques, #O. chungarensis ressemble à #O. gracilis$. (Résumé d'auteur

    P-248 Futility and utility of two-stage hepatectomy

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    Meeting abstract in the European-Society-for-Medical-Oncology (ESMO) 21st World Congress on Gastrointestinal Cancer.info:eu-repo/semantics/publishedVersio

    Experimental realization of the Yang-Baxter Equation via NMR interferometry

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    The Yang-Baxter equation is an important tool in theoretical physics, with many applications in different domains that span from condensed matter to string theory. Recently, the interest on the equation has increased due to its connection to quantum information processing. It has been shown that the Yang-Baxter equation is closely related to quantum entanglement and quantum computation. Therefore, owing to the broad relevance of this equation, besides theoretical studies, it also became significant to pursue its experimental implementation. Here, we show an experimental realization of the Yang-Baxter equation and verify its validity through a Nuclear Magnetic Resonance (NMR) interferometric setup. Our experiment was performed on a liquid state Iodotrifluoroethylene sample which contains molecules with three qubits. We use Controlled-transfer gates that allow us to build a pseudo-pure state from which we are able to apply a quantum information protocol that implements the Yang-Baxter equation.Comment: 10 pages and 6 figure
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