2,867 research outputs found
Particle yields in heavy ion collisions and the influence of strong magnetic fields
It is expected that the magnetic field in the surface of magnetars do not
exceed G. However, in heavy ion collisions, this value is expected to
be much higher. We investigate the effects of a magnetic fields varying from
, to G in strange matter (composed of , and
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 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 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
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
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
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 Kapsnerâs idea of superconnexivity
Object Persistency for HEP data using an Object-Relational Database
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
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), morphineâ3âglucuronide (M3G) and morphineâ6âglucuronide (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 6âmonoacetylmorphine (6âMAM) in any of the postmortem samples was used as confirmation of heroin use. Quantitation was carried out using a validated LCâMS/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 6âMAM (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, morphineâ3âglucuronide or morphineâ6âglucuronide 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
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
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.
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 (âŒ188,000 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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