2,856 research outputs found

    Particle yields in heavy ion collisions and the influence of strong magnetic fields

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    It is expected that the magnetic field in the surface of magnetars do not exceed 101510^{15} G. However, in heavy ion collisions, this value is expected to be much higher. We investigate the effects of a magnetic fields varying from 101810^{18}, to 102010^{20} G in strange matter (composed of uu, dd and ss quarks). We model matter as a free gas of baryons and mesons under the influence of an external magnetic field. We study the effects of such strong fields through a χ2\chi^2 fit to some data sets of the STAR experiment. For this purpose we solve the Dirac, Rarita-Schwinger, Klein-Gordon and Proca equations subject to magnetic fields in order to obtain the energy expressions and the degeneracy for spin 1/2, spin 3/2, spin 0 and spin 1 particles, respectively. Our results show that a field of the order of 101910^{19} G produces an improved fitting to the experimental data as compared to the calculations without magnetic field.Comment: 20 pages, 16 figures, 4 table

    Landau parameters for isospin asymmetric nuclear matter based on a relativistic model of composite and finite extension nucleons

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    We study the properties of cold asymmetric nuclear matter at high density, applying the quark meson coupling model with excluded volume corrections in the framework of the Landau theory of relativistic Fermi liquids. We discuss the role of the finite spatial extension of composite baryons on dynamical and statistical properties such as the Landau parameters, the compressibility, and the symmetry energy. We have also calculated the low lying collective eigenfrequencies arising from the collisionless quasiparticle transport equation, considering both unstable and stable modes. An overall analysis of the excluded volume correlations on the collective properties is performed.Comment: 24 pages, 6 figure

    Volume geodesic distortion and Ricci curvature for Hamiltonian dynamics

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    We study the variation of a smooth volume form along extremals of a variational problem with nonholonomic constraints and an action-like Lagrangian. We introduce a new invariant describing the interaction of the volume with the dynamics and we study its basic properties. We then show how this invariant, together with curvature-like invariants of the dynamics, appear in the expansion of the volume at regular points of the exponential map. This generalizes the well-known expansion of the Riemannian volume in terms of Ricci curvature to a wide class of geometric structures, including all sub-Riemannian manifolds

    Intuitionistic logic as a connexive logic

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    We show that intuitionistic logic is deductively equivalent to Connexive Heyting Logic (CHL), hereby introduced as an example of a strongly connexive logic with an intuitive semantics. We use the reverse algebraisation paradigm: CHL is presented as the assertional logic of a point regular variety (whose structure theory is examined in detail) that turns out to be term equivalent to the variety of Heyting algebras. We provide Hilbert-style and Gentzen-style proof systems for CHL ; moreover, we suggest a possible computational interpretation of its connexive conditional, and we revisit Kapsner’s idea of superconnexivity

    Object Persistency for HEP data using an Object-Relational Database

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    We present an initial study of the object features of Oracle 9i - the first of the market-leading object-relational database systems that supports a true object model on the server side as well as an ODMG-style C++ language binding on the client side. We discuss how these features can be used to provide persistent object storage in the HEP environment

    Postmortem tissue distribution of morphine and its metabolites in a series of heroin related deaths

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    The abuse of heroin (diamorphine) and heroin deaths are growing around the world. The interpretation of the toxicological results from suspected heroin deaths is notoriously difficult especially in cases where there may be limited samples. In order to help forensic practitioners with heroin interpretation we determined the concentration of morphine (M), morphine‐3‐glucuronide (M3G) and morphine‐6‐glucuronide (M6G) in blood (femoral and cardiac), brain (thalamus), liver (deep right lobe), bone marrow (sternum), skeletal muscle (psoas) and vitreous humor in 44 heroin related deaths. The presence of 6‐monoacetylmorphine (6‐MAM) in any of the postmortem samples was used as confirmation of heroin use. Quantitation was carried out using a validated LC‐MS/MS method with solid phase extraction. We also determined the presence of papaverine, noscapine and codeine in the samples, substances often found in illicit heroin and that may help determine illicit heroin use. The results of this study show that vitreous is the best sample to detect 6‐MAM (100% of cases), and thus heroin use. The results of the M, M3G and M6G quantitation in this study allow a degree of interpretation when samples are limited. However in some cases it may not be possible to determine heroin/morphine use as in 4 cases in muscle (3 cases in bone marrow) no morphine, morphine‐3‐glucuronide or morphine‐6‐glucuronide was detected, even though they were detected in other case samples. As always postmortem cases of suspected morphine/heroin intoxication should be interpreted with care and with as much case knowledge as possible

    The Rarita-Schwinger Particles Under de Influence of Strong Magnetic Fields

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    In this work, we calculate the solutions of the Rarita-Schwinger equation with the inclusion of the eletromagnetic interaction. Our gauge and coupling prescription choices lead to Dirac-type solutions. One of the consequences of our results are the Landau level occupation of particles, quite different from the usual spin 1/2 particle system occupation numbers.Comment: 12 page

    Phosphorus Efficiency Of Bornean Rain Forest Productivity: Evidence Against The Unimodal Efficiency Hypothesis

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/117012/1/ecy20058661548.pd

    Effect of oil palm sustainability certification on deforestation and fire in Indonesia.

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    Many major corporations and countries have made commitments to purchase or produce only "sustainable" palm oil, a commodity responsible for substantial tropical forest loss. Sustainability certification is the tool most used to fulfill these procurement policies, and around 20% of global palm oil production was certified by the Roundtable on Sustainable Palm Oil (RSPO) in 2017. However, the effect of certification on deforestation in oil palm plantations remains unclear. Here, we use a comprehensive dataset of RSPO-certified and noncertified oil palm plantations (∌188,000 km2) in Indonesia, the leading producer of palm oil, as well as annual remotely sensed metrics of tree cover loss and fire occurrence, to evaluate the impact of certification on deforestation and fire from 2001 to 2015. While forest loss and fire continued after RSPO certification, certified palm oil was associated with reduced deforestation. Certification lowered deforestation by 33% from a counterfactual of 9.8 to 6.6% y-1 Nevertheless, most plantations contained little residual forest when they received certification. As a result, by 2015, certified areas held less than 1% of forests remaining within Indonesian oil palm plantations. Moreover, certification had no causal impact on forest loss in peatlands or active fire detection rates. Broader adoption of certification in forested regions, strict requirements to avoid all peat, and routine monitoring of clearly defined forest cover loss in certified and RSPO member-held plantations appear necessary if the RSPO is to yield conservation and climate benefits from reductions in tropical deforestation
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