Strangeness production at finite temperature and baryon density in an effective relativistic mean field model

We study the strangeness production in hot and dense nuclear medium, by requiring the conservation of the baryon density, electric charge fraction and zero net strangeness. The hadronic equation of state is investigated by means of an effective relativistic mean field model, with the inclusion of the full octet of baryons and kaon mesons. Kaons are considered taking into account of an effective chemical potential depending on the self-consistent interaction between baryons. The obtained results are compared with a minimal coupling scheme, calculated for different values of the anti-kaon optical potential and with non-interacting kaon particles. In this context, we also consider the possible onset of the kaon condensation for a wide range of temperatures and baryon densities.Comment: 13 pages, 6 figure

Nonlinear statistical effects in relativistic mean field theory

We investigate the relativistic mean field theory of nuclear matter at finite temperature and baryon density taking into account of nonlinear statistical effects, characterized by power-law quantum distributions. The analysis is performed by requiring the Gibbs conditions on the global conservation of baryon number and electric charge fraction. We show that such nonlinear statistical effects play a crucial role in the equation of state and in the formation of mixed phase also for small deviations from the standard Boltzmann-Gibbs statistics.Comment: 9 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:1005.4643 and arXiv:0912.460

Nonextensive statistical effects in the hadron to quark-gluon phase transition

We investigate the relativistic equation of state of hadronic matter and quark-gluon plasma at finite temperature and baryon density in the framework of the nonextensive statistical mechanics, characterized by power-law quantum distributions. We study the phase transition from hadronic matter to quark-gluon plasma by requiring the Gibbs conditions on the global conservation of baryon number and electric charge fraction. We show that nonextensive statistical effects play a crucial role in the equation of state and in the formation of mixed phase also for small deviations from the standard Boltzmann-Gibbs statistics.Comment: 13 pages, 10 figure

Strangeness thermodynamic instabilities in hot and dense nuclear matter

We explore the presence of thermodynamic instabilities and, consequently, the realization of a pure hadronic phase transition in the hot and finite baryon density nuclear matter. The analysis is performed by means of an effective relativistic mean-field model with the inclusion of hyperons, Δ-isobars, and the lightest pseudoscalar and vector meson degrees of freedom. The Gibbs conditions on the global conservation of baryon number and zero net strangeness in symmetric nuclear matter are required. Similarly to the liquid–gas phase transition, we show that a phase transition, characterized by mechanical instabilities (due to fluctuations on the baryon number) and chemical-diffusive instabilities (due to fluctuations on the strangeness number), can take place for a finite range of Δ-meson coupling constants, compatible with different experimental constraints. The hadronic phase transition, which presents similar features to the quark-hadron phase transition, is characterized by different strangeness content during the mixed phase and, consequently, by a sensible variation of the strange anti-particle to particle ratios

Quantum thermodynamic instabilities in compact stars

We study the existence of thermodynamic instabilities in the nuclear equation of state relative to the high density regime reached in the central core of compact stars. In the framework of a relativistic mean-field theory, we analyze the asymmetric nuclear properties in beta-equilibrium, including hyperons and Delta-isobar degrees of freedom. We investigate a finite density phase transition characterized by pure hadronic matter with the presence of mechanical instability (relative to the fluctuation of baryon number) and of chemical-dffusive instability (relative to the fluctuation of electric charge concentration). We find that, in the presence of thermodynamic instabilities, two hadronic phases with dfferent values of electric charge content may coexist, with several phenomenological consequences in the physics of compact stars

Nonlinear Nuclear Equation of State and Thermodynamical Instabilities in Warm and Dense Nuclear Matter

We study a nonlinear nuclear equation of state in the framework of a relativistic mean field theory. We investigate the possible thermodynamic instability in a warm and dense asymmetric nuclear medium where a phase transition from nucleonic matter to resonance dominated Δ matter can take place. Such a phase transition is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fluctuations on the isospin concentration) in asymmetric nuclear matter. Similarly to the liquid-gas phase transition, the nucleonic and the Δ-matter phase have a different isospin density in the mixed phase. In the liquid-gas phase transition, the process of producing a larger neutron excess in the gas phase is referred to as isospin fractionation. A similar effects can occur in the nucleon-Δ matter phase transition due essentially to a negative Δ-particles excess in asymmetric nuclear matter. In this context, we investigate also the effects of power law effects, due to the possible presence of nonextensive statistical mechanics effect

Chemical and mechanical instabilities in high energy heavy-ion collisions

We investigate the possible thermodynamic instability in a warm and dense nuclear medium where a phase transition from nucleonic matter to resonance-dominated Delta-matter can take place. Such a phase transition is characterized by both mechanical instability (fluctuations on the baryon density) and by chemical-diffusive instability (fuctuations onthe isospin concentration) in asymmetric nuclear matter. Similarly to the liquid-gas phase transition, the nucleonic and the Delta-matter phase have a different isospin density in the mixed phase. In the liquid-gas phase transition, the process of producing a larger neutron excess in the gas phase is referred to as isospin fractionation. A similar effects can occur in the nucleon-Delta matter phase transition due essentially to a Delta- excess in the Delta-matter phase in asymmetric nuclear matter. In this context, we study the hadronic equation of state by means of an effective quantum relativistic mean field model with the inclusion of the full octet of baryons, the Delta-isobar degrees of freedom, and the lightest pseudoscalar and vector mesons. Finally, we will investigate the presence of thermodynamic instabilities in a hot and dense nuclear medium where phases with different values of antibaryon-baryon ratios and strangeness content may coexist. Such a physical regime could be in principle investigated in the future high-energy compressed nuclear matter experiments where will make it possible to create compressed baryonic matter with a high net baryon density

Power-law quantum distributions in protoneutron stars

We investigate the bulk properties of protoneutron stars in the framework of a relativistic mean field theory based on nonextensive statistical mechanics, originally proposed by C. Tsallis and characterized by power-law quantum distributions. We study the relevance of nonextensive statistical effects on the β-stable equation of state at fixed entropy per baryon, for nucleonic and hyperonic matter. We concentrate our analysis in the maximum heating and entropy per baryon s = 2 stage and T ≈ 40 ÷ 80 MeV. This is the phase, at high temperature and high baryon density, in which the presence of nonextensive effects may alter more sensibly the thermodynamical and mechanical properties of the protoneutron star. We show that nonextensive power-law effects could play a crucial role in the structure and in the evolution of the protoneutron stars also for small deviations from the standard Boltzmann-Gibbs statistics

Nonextensive statistical effects in protoneutron stars

We investigate the bulk properties of protoneutron stars in the framework of a relativistic mean field theory based on nonextensive statistical mechanics, characterized by power-law quantum distributions. We study the relevance of nonextensive statistical effects on the beta-stable equation of state at fixed entropy per baryon, in presence and in absence of trapped neutrinos, for nucleonic and hyperonic matter. We show that nonextensive statistical effects could play a crucial role in the structure and in the evolution of the protoneutron stars also for small deviations from the standard Boltzmann-Gibbs statistics.Comment: 9 pages, 7 figure

PERFIL MICROBIOLÓGICO DE QUINDINS

Quindim is a typical Brazilian sweet and being a food that requires manual preparation, there are factors that contribute to its contamination by pathogenic microorganisms. The foodborne disease (FBD's) are caused by micro-organisms capable of generating food infections and food poisoning, have a clear clinical characteristic determined by demonstrations gastrointestinal such as diarrhea, abdominal pain, nausea, vomiting, accompanied by fever or not . The aim of this study is to detect micro organisms in quindins, according to the norms established by ANVISA RDC number 12. We analyzed 10 samples of 4 different establishments, by microbiological identification methods and biochemistry. Tests were positive for Salmonella spp., Staphylococcus aureus, Bacillus cereus and Escherichia coli. With this, it is concluded that the quindins were unfit for consumption. Therefore, the microbiological examination of foods and quality control are necessary, since the manipulation, storage, exposure and care sanitary toilet to food ingestion by the consumer, in order to avoid infections and intoxications associated with pathogenic microorganisms.Quindim é um doce tipicamente brasileiro e por ser um alimento que exige preparação manual, há fatores que contribuem para a sua contaminação por micro-organismos patogênicos. As doenças transmitidas por alimentos (DTA"™s) são ocasionadas por micro-organismos capazes de gerar infecções alimentares e intoxicações alimentares, apresentam um quadro clí­nico bem caracterí­stico, determinado por manifestações gastro intestinais como diarréia, dor abdominal, náuseas, vômitos, acompanhados de febre. O objetivo deste estudo é detectar micro-organismos em quindins, de acordo com as normas estabelecidas pela RDC nº 12 da ANVISA. Foram analisadas 10 amostras de 4 estabelecimentos diferentes, pelos métodos de identificação microbiológica e bioquí­mica. Os testes apresentaram-se positivos para Salmonella spp., Staphylococcus aureus, Bacillus cereus e Escherichia coli. Com isto, conclui-se que os quindins encontravam-se impróprios para consumo. Portanto, a análise microbiológica dos alimentos e o controle de qualidade se fazem necessários, desde a manipulação, armazenamento, exposição e o cuidado higiênico sanitário até a ingestão do alimento pelo consumidor final, a fim de se evitar infecções e intoxicações associadas à micro-organismos patogênicos