Chiral symmetry restoration in excited hadrons, quantum fluctuations, and quasiclassics

In this paper, we discuss the transition to the semiclassical regime in excited hadrons, and consequently, the restoration of chiral symmetry for these states. We use a generalised Nambu-Jona-Lasinio model with the interaction between quarks in the form of the instantaneous Lorentz-vector confining potential. This model is known to provide spontaneous breaking of chiral symmetry in the vacuum via the standard selfenergy loops for valence quarks. It has been shown recently that the effective single-quark potential is of the Lorentz-scalar nature, for the low-lying hadrons, while, for the high-lying states, it becomes a pure Lorentz vector and hence the model exhibits the restoration of chiral symmetry. We demonstrate explicitly the quantum nature of chiral symmetry breaking, the absence of chiral symmetry breaking in the classical limit as well as the transition to the semiclassical regime for excited states, where the effect of chiral symmetry breaking becomes only a small correction to the classical contributions.Comment: RevTeX4, 20 pages, 4 Postscript figures, uses epsfig.sty, typos correcte

Chiral symmetry and excited baryons

An approach to baryons in the framework of the microscopic Generalized Nambu-Jona-Lasinio chiral potential quark model is considered and quite general arguments are given in favor of effective restoration of chiral symmetry in excited baryons.Comment: LaTeX2e, 5 pages, uses jetpl.cls (included), to appear in JETP Let

Dark quark domains

Formation of stable domains filled with strongly correlated coherent quark matter is discussed in general terms and is exemplified further in the framework of the Generalised Nambu-Jona-Lasinio model. It is argued that such domains, if exist in the Universe, appear dark to an external observer.Comment: LaTeX2e, 5 pages, uses jetpl.cls (included), to appear in JETP Let

Renormalization Group Approach to Einstein Equation in Cosmology

The renormalization group method has been adapted to the analysis of the long-time behavior of non-linear partial differential equation and has demonstrated its power in the study of critical phenomena of gravitational collapse. In the present work we apply the renormalization group to the Einstein equation in cosmology and carry out detailed analysis of renormalization group flow in the vicinity of the scale invariant fixed point in the spherically symmetric and inhomogeneous dust filled universe model.Comment: 16 pages including 2 eps figures, RevTe

Symmetry and magnetically driven ferroelectricity in rare-earth manganites RMnO3 (R=Gd, Tb, Dy)

This work investigates the magnetically driven ferroelectricity in orthorhombic manganites RMnO3 (R=Gd, Dy or Tb) from the point of view of the symmetry. The method adopted generalizes the one used to characterize the polar properties of displacive modulated structures to the case of an irreducible magnetic order parameter. The symmetry conditions for magnetically induced ferroelectricity are established and the Landau-Devonshire free energy functionals derived from general symmetry considerations. The ferroelectric polarisation observed in DyMnO3 and TbMnO3 at zero magnetic field is explained in terms of the symmetry of a reducible magnetic order parameter. The polarisation rotation induced in these compounds by external magnetic fields and the stabilization of a ferroelectric phase in GdMnO3 are accounted for by a mechanism in which magnetization and polarization are secondary order parameters that are not directly coupled but compete with each other through their coupling to competing primary modulated order parameters.Comment: Article submitted to Physical Review B, 39 page

Febre Amarela: revisão e situação epidemiológica atual no Brasil

Desde Janeiro de 2017, foram reportados 1563 casos suspeitos de Febre Amarela, sendo confirmados 629 casos, dos quais foram confirmadas 232 mortes devido a doença. A Febre Amarela é uma doença febril hemorrágica, sendo endêmica de regiões tropicais da África e América do Sul. Nos dias atuais, tem apresentado aumento significativo em sua incidência no Brasil, com repercussões e impactos importantes na saúde pública do país. Neste artigo são descritas as causas de Febre Amarela, bem como sua epidemiologia, progressão, os métodos diagnósticos, tratamento e prevenção da doença, de forma a promover atualização epidemiológica e direcionar futuras pesquisas na área. Método: Foram utilizados dados do Pubmed, SciELO, Medline e de fontes governamentais, referentes a Febre Amarela, que datam de 2002 à 2018. Na coleta do dados foram utilizados os seguintes descritores: Febre Amarela, Aedes, Arbovírus, Flavivirus.Since January 2017, there have been at least 1563 suspected cases of Yellow Fever, 629 confirmed cases and 232 confirmed deaths. Yellow fever is a viral hemorrhagic disease endemic to the tropical parts of Africa and South America. At the present time, it has presented a significant increase in its incidence in Brazil, with important repercussions and impacts on the public health. This review paper outlines the causes of yellow fever, as well as the disease epidemiology, progression, diagnosis, treatment and prevention. We conclude by reporting on the current epidemic in Brazil and future directions for research. Method: Data from Pubmed, SciELO, Medline and government sources concerning Yellow Fever were used, dating from 2002 to 2018. In the collection of the data the following descriptors were used: Yellow-fever, Aedes, Arbovirus and Flavivirus

Magnetic superspace groups and symmetry constraints in incommensurate magnetic phases

Although superspace formalism has become the standard approach for the analysis of structurally modulated crystals, it has remained during the last thirty years almost unexplored as a practical tool to deal with magnetic incommensurate structures. This situation has recently changed with the development of new computer tools for magnetic phases based on this formalism. In this context we show here that, as in the case of nonmagnetic incommensurate systems, the concept of superspace symmetry provides a simple, efficient and systematic way to characterize the symmetry and rationalize the structural and physical properties of incommensurate magnetic materials. The method introduces significant advantages over the most commonly employed method of representation analysis for the description of the magnetic structure of a crystal. But, more importantly, in contrast with that method, it consistently yields and classifies all degrees of freedom of the system. The knowledge of the superspace group of an incommensurate magnetic material allows to predict its crystal tensor properties and to rationalize its phase diagram, previous to any appeal to microscopic models or mechanisms. This is especially relevant when the properties of incommensurate multiferroics are being studied. We present first a summary of the superspace method under a very practical viewpoint particularized to magnetic modulations. Its relation with the usual representation analysis is then analyzed in detail, with the derivation of important general rules for magnetic modulations with a single propagation vector. The power and efficiency of the formalism is illustrated with various selected examples, including some multiferroic materials

Changes in the red giant and dusty environment of the recurrent nova RS Ophiuchi following the 2006 eruption

We present near-infrared spectroscopy of the recurrent nova RS Ophiuchi (RS Oph) obtained on several occasions after its latest outburst in 2006 February. The 1–5 μm spectra are dominated by the red giant, but the H i, He i and coronal lines present during the eruption are present in all our observations. From the fits of the computed infrared spectral energy distributions to the observed fluxes, we find Teff= 4200 ± 200 K for the red giant. The first overtone CO bands at 2.3 μm, formed in the atmosphere of the red giant, are variable. The spectra clearly exhibit an infrared excess due to dust emission longward of 5 μm; we estimate an effective temperature for the emitting dust shell of 500 K, and find that the dust emission is also variable, being beyond the limit of detection in 2007. Most likely, the secondary star in RS Oph is intrinsically variable

Host Immune Response to Mosquito-Transmitted Chikungunya Virus Differs from That Elicited by Needle Inoculated Virus

Mosquito-borne diseases are a worldwide public health threat. Mosquitoes transmit viruses or parasites during feeding, along with salivary proteins that modulate host responses to facilitate both blood feeding and pathogen transmission. Understanding these earliest events in mosquito transmission of arboviruses by mosquitoes is essential for development and assessment of rational vaccine and treatment strategies. In this report, we compared host immune responses to chikungunya virus (CHIKV) transmission by (1) mosquito bite, or (2) by needle inoculation.Differential cytokine expression was measured using quantitative real-time RT-PCR, at sites of uninfected mosquito bites, CHIKV-infected mosquito bites, and needle-inoculated CHIKV. Both uninfected and CHIKV infected mosquitoes polarized host cytokine response to a TH2 profile. Compared to uninfected mosquito bites, expression of IL-4 induced by CHIKV-infected mosquitoes were 150 fold and 527.1 fold higher at 3 hours post feeding (hpf) and 6 hpf, respectively. A significant suppression of TH1 cytokines and TLR-3 was also observed. These significant differences may result from variation in the composition of uninfected and CHIKV-infected mosquito saliva. Needle injected CHIKV induced a robust interferon-gamma, no detectable IL-4, and a significant up-regulation of TLR-3.This report describes the first analysis of cutaneous cytokines in mice bitten by CHIKV-infected mosquitoes. Our data demonstrate contrasting immune activation in the response to CHIKV infection by mosquito bite or needle inoculation. The significant role of mosquito saliva in these earliest events of CHIKV transmission and infection are highlighted

Enhanced magneto-optical oscillations from two-dimensional hole-gases in the presence of Mn ions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)We investigated the effects of nearby Mn ions on the optical properties of two-dimensional hole-gases confined in InGaAs/GaAs quantum wells. We observed energy oscillations on both the averaged emission and the spin-splitting energies, whereas the first one presents maxima at all integer filling factors, and the second one, solely at odd-filling factors. The strength of the oscillations clearly increases with the Mn concentration. Furthermore, considering the relatively low-mobility of our structures, the oscillations are surprisingly strong and robust, persisting up to relatively high temperatures and excitation intensities. (C) 2011 American Institute of Physics. [doi:10.1063/1.3601477]9825Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Ministry of Education and Science of Russian Federation [RNP 2.2.2.2/4737, 2.2.2.2/11107]Civilian Research and Development Foundation [RUXO-001-NN-06/BP1M01]Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Ministry of Education and Science of Russian Federation [RNP 2.2.2.2/4737, 2.2.2.2/11107]Civilian Research and Development Foundation [RUXO-001-NN-06/BP1M01