Dynamical light vector mesons in low-energy scattering of Goldstone bosons

We present a study of Goldstone boson scattering based on the flavor SU(3) chiral Lagrangian formulated with vector mesons in the tensor field representation. A coupled-channel channel computation is confronted with the empirical s- and p-wave phase shifts, where good agreement with the data set is obtained up to about 1.2 GeV. There are two relevant free parameters only, the chiral limit value of the pion decay constant and the coupling constant characterizing the decay of the rho meson into a pair of pions. We apply a recently suggested approach that implements constraints from micro- causality and coupled-channel unitarity. Generalized potentials are obtained from the chiral Lagrangian and are expanded in terms of suitably constructed conformal variables. The partial-wave scattering amplitudes are defined as solutions of non-linear integral equations that are solved by means of an N/D ansatz.Comment: 15 pages, 8 figures, typos corrected, accepted for publication in Physics Letters

Reducing sample variance: halo biasing, non-linearity and stochasticity

Comparing clustering of differently biased tracers of the dark matter distribution offers the opportunity to reduce the cosmic variance error in the measurement of certain cosmological parameters. We develop a formalism that includes bias non-linearities and stochasticity. Our formalism is general enough that can be used to optimise survey design and tracers selection and optimally split (or combine) tracers to minimise the error on the cosmologically interesting quantities. Our approach generalises the one presented by McDonald & Seljak (2009) of circumventing sample variance in the measurement of $f\equiv d \ln D/d\ln a$. We analyse how the bias, the noise, the non-linearity and stochasticity affect the measurements of $Df$ and explore in which signal-to-noise regime it is significantly advantageous to split a galaxy sample in two differently-biased tracers. We use N-body simulations to find realistic values for the parameters describing the bias properties of dark matter haloes of different masses and their number density. We find that, even if dark matter haloes could be used as tracers and selected in an idealised way, for realistic haloes, the sample variance limit can be reduced only by up to a factor $\sigma_{2tr}/\sigma_{1tr}\simeq 0.6$. This would still correspond to the gain from a three times larger survey volume if the two tracers were not to be split. Before any practical application one should bear in mind that these findings apply to dark matter haloes as tracers, while realistic surveys would select galaxies: the galaxy-host halo relation is likely to introduce extra stochasticity, which may reduce the gain further.Comment: 21 pages, 13 figures. Published version in MNRA

The braking indices in pulsar emission models

Using the method proposed in a previous paper, we calculate pulsar braking indices in the models with torque contributions from both inner and outer accelerating regions, assuming that the interaction between them is negligible. We suggest that it is likely that the inverse Compton scattering induced polar vacuum gap and the outer gap coexist in the pulsar magnetosphere. We include the new near threshold vacuum gap models with curvature-radiation and inverse Compton scattering induced cascades, respectively; and find that these models can well reproduce the measured values of the braking indices.Comment: A&Ap accepted, or at http://vega.bac.pku.edu.cn/~rxxu/publications/index_P.ht

Seeing Star Formation Regions with Gravitational Microlensing

We qualitatively study the effects of gravitational microlensing on our view of unresolved extragalactic star formation regions. Using a general gravitational microlensing configuration, we perform a number of simulations that reveal that specific imprints of the star forming region are imprinted, both photometrically and spectroscopically, upon observations. Such observations have the potential to reveal the nature and size of these star forming regions, through the degree of variability observed in a monitoring campaign, and hence resolve the star formation regions in distant galaxies which are too small to be probed via more standard techniques.Comment: 7 pages, 8 figures, ApJ accepte

Quark mass dependence of the Ds0∗(2317)D_{s0}^*(2317)

We determine the quark mass dependence - light and heavy - of the $D_{s0}(2317)$ properties, such as, mass, coupling to $DK$, scattering lengths and compositeness, from a global analysis of $DK$ energy levels from LQCD. In particular, we analyze the HSC energy levels for $DK$ scattering in $I=0$ for different boosts and two pion masses. The formalism is based in the local hidden-gauge interaction of Weinberg-Tomozawa type which respects chiral and heavy quark spin symmetries, supplemented by a term that takes into account the $DK$ coupling to a bare $c\bar{s}$ component. The isospin violating decay of the $D_{s0}(2317)\to D_{s}^+\pi^0$ is also evaluated

Quasar Microlensing: when compact masses mimic smooth matter

The magnification induced by gravitational microlensing is sensitive to the size of a source relative to the Einstein radius, the natural microlensing scale length. This paper investigates the effect of source size in the case where the microlensing masses are distributed with a bimodal mass function, with solar mass stars representing the normal stellar masses, and smaller masses (down to $8.5\times 10^{-5}$M$_\odot$) representing a dark matter component. It is found that there exists a critical regime where the dark matter is initially seen as individual compact masses, but with an increasing source size the compact dark matter acts as a smooth mass component. This study reveals that interpretation of microlensing light curves, especially claims of small mass dark matter lenses embedded in an overall stellar population, must consider the important influence of the size of the source.Comment: 6 pages, to appear in ApJ. As ever, quality of figures reduce

On the calibration of the relation between geometric albedo and polarimetric properties for the asteroids

We present a new extensive analysis of the old problem of finding a satisfactory calibration of the relation between the geometric albedo and some measurable polarization properties of the asteroids. To achieve our goals, we use all polarimetric data at our disposal. For the purposes of calibration, we use a limited sample of objects for which we can be confident to know the albedo with good accuracy, according to previous investigations of other authors. We find a new set of updated calibration coefficients for the classical slope - albedo relation, but we generalize our analysis and we consider also alternative possibilities, including the use of other polarimetric parameters, one being proposed here for the first time, and the possibility to exclude from best-fit analyzes the asteroids having low albedos. We also consider a possible parabolic fit of the whole set of data.Comment: Accepted by MNRA

The first confirmation of V-type asteroids among the Mars crosser population

The Mars crossing region constitutes a path to deliver asteroids from the Inner Main Belt to the Earth crossing space. While both the Inner Main Belt and the population of Earth crossing asteroids contains a significant fraction of asteroids belonging to the V taxonomic class, only two of such V-type asteroids has been detected in the Mars crossing region up to now. In this work, we searched for asteroids belonging to the V class among the population of Mars crossing asteroids, in order to support alternative paths to the delivery of this bodies into the Earth crossing region. We selected 18 candidate V-type asteroids in the Mars crossing region using observations contained in the Sloan Digital Sky Survey Moving Objects Catalog. Then, we observed 4 of these candidates to take their visible spectra using the Southern Astrophysical Research Telescope (SOAR). We also performed the numerical simulation of the orbital evolution of the observed asteroids. We confirmed that 3 of the observed asteroids belong to the V class, and one of these may follow a path that drives it to an Earth collision in some tens of million years

Projeto Rondon no município de Caridade – CE: avaliação dos resultados obtidos com as feiras da saúde

Trabalho apresentado no II Congresso Nacional do PROJETO RONDON, realizado em Florianópolis, SC, no período de 23 a 25 de setembro de 2015 - Universidade Federal de Santa Catarina.A Organização Mundial de Saúde (OMS) classifica as condições de saúde em agudas e crônicas, tendo a Hipertensão Arterial Sistêmica (HAS) e o Diabetes Mellitus (DM) como condições crônico-degenerativas de saúde. Assim, tais patologias recebem atenção especial do sistema de saúde, haja vista a alta prevalência das complicações cardiovasculares, cerebrovasculares, nefrológicas e visuais oriundas dessas doenças. Nesse sentido, essas afecções e seus agravos necessitam de ações efetivas de promoção e prevenção da saúde. A Feira da Saúde foi uma das oficinas do Centro Universitário de Patos de Minas – UNIPAM durante o Projeto Rondon de Janeiro/2015 - Operação Mandacaru em Caridade - CE. As ações basearam-se na realização de um circuito de atendimento, no qual o paciente foi acolhido e devidamente identificado e a seguir, foram coletadas e registradas, em uma ficha própria desenvolvida para a feira, informações de saúde desses indivíduos. Ao final do circuito, cada pessoa atendida apresentou esse instrumento a um rondonista. Após a avaliação dos dados encontrados na ficha, o membro da equipe dialogou com o paciente, dando ênfase em orientações que, de acordo com as evidências científicas, reduzem a mortalidade, como uma alimentação saudável, a prática regular de atividade física, a redução ou abolição do consumo de bebidas alcóolicas, tabaco e outras drogas e a utilização correta de medicamentos para o controle da Hipertensão Arterial e do Diabetes Mellitus. Ao longo da realização do Projeto Rondon no município, esta oficina foi desenvolvida quatro vezes, em Caridade e nos distritos de São Domingos e Ipueira dos Gomes, ultrapassando o número de 250 indivíduos atendidos. Desses, 135 tiveram suas fichas sorteadas aleatoriamente para a avaliação do perfil dos pacientes acolhidos nas feiras de saúde. Dentre os resultados obtidos, perceberam-se nitidamente os hábitos de vida desfavoráveis para o aparecimento e a progressão das doenças crônicas, sendo relevante citar o percentual elevado de pacientes com sobrepeso e obesidade e o sedentarismo, este último observado através dos mais de 80% dos pacientes que não praticavam nenhuma atividade física. Portanto, acredita-se que as Feiras da Saúde foram de suma importância para a conscientização da população desse município para o autocuidado orientado através de hábitos de vida saudáveis

Structurally altered capsular polysaccharides produced by mutant bacteria

Structurally altered capsular polysaccharides are produced by mutant bacteria. These polysaccharides are isolated by selecting a wild type bacterial strain and a phage producing degradative enzymes that have substrate specificity for the capsular polysaccharides produced by the wild type bacteria. Phage-resistant mutants producing capsular polysaccharides are selected and the structurally altered capsular polysaccharide is isolated therefrom