Cluster Structures with Machine Learning Support in Neutron Star M-R relations

Neutron stars (NS) are compact objects with strong gravitational fields, and a matter composition subject to extreme physical conditions. The properties of strongly interacting matter at ultra-high densities and temperatures impose a big challenge to our understanding and modelling tools. Some difficulties are critical, since one cannot reproduce such conditions in our laboratories or assess them purely from astronomical observations. The information we have about neutron star interiors are often extracted indirectly, e.g., from the star mass-radius relation. The mass and radius are global quantities and still have a significant uncertainty, which leads to great variability in studying the micro-physics of the neutron star interior. This leaves open many questions in nuclear astrophysics and the suitable equation of state (EoS) of NS. Recently, new observations appear to constrain the mass-radius and consequently has helped to close some open questions. In this work, utilizing modern machine learning techniques, we analyze the NS mass-radius (M-R) relationship for a set of EoS containing a variety of physical models. Our objective is to determine patterns through the M-R data analysis and develop tools to understand the EoS of neutron stars in forthcoming works.Comment: Contribution to the XLIV Brazilian Workshop on Nuclear Physics, Brazi

Stellar equilibrium configurations of white dwarfs in the f(R,T)f(R,T) gravity

In this work we investigate the equilibrium configurations of white dwarfs in a modified gravity theory, na\-mely, $f(R,T)$ gravity, for which $R$ and $T$ stand for the Ricci scalar and trace of the energy-momentum tensor, respectively. Considering the functional form $f(R,T)=R+2\lambda T$, with $\lambda$ being a constant, we obtain the hydrostatic equilibrium equation for the theory. Some physical properties of white dwarfs, such as: mass, radius, pressure and energy density, as well as their dependence on the parameter $\lambda$ are derived. More massive and larger white dwarfs are found for negative values of $\lambda$ when it decreases. The equilibrium configurations predict a maximum mass limit for white dwarfs slightly above the Chandrasekhar limit, with larger radii and lower central densities when compared to standard gravity outcomes. The most important effect of $f(R,T)$ theory for massive white dwarfs is the increase of the radius in comparison with GR and also $f(R)$ results. By comparing our results with some observational data of massive white dwarfs we also find a lower limit for $\lambda$, namely, $\lambda >- 3\times 10^{-4}$.Comment: To be published in EPJ

GRB 170817A-GW170817-AT 2017gfo and the observations of NS-NS, NS-WD and WD-WD mergers

The LIGO-Virgo Collaboration has announced the detection of GW170817 and has associated it with GRB 170817A. These signals have been followed after 11 hours by the optical and infrared emission of AT 2017gfo. The origin of this complex phenomenon has been attributed to a neutron star-neutron star (NS-NS) merger. In order to probe this association we confront our current understanding of the gravitational waves and associated electromagnetic radiation with four observed GRBs originating in binaries composed of different combinations NSs and white dwarfs (WDs). We consider 1) GRB 090510 the prototype of NS-NS merger leading to a black hole (BH); 2) GRB 130603B the prototype of a NS-NS merger leading to massive NS (MNS) with an associated kilonova; 3) GRB 060614 the prototype of a NS-WD merger leading to a MNS with an associated kilonova candidate; 4) GRB 170817A the prototype of a WD-WD merger leading to massive WD with an associated AT 2017gfo-like emission. None of these systems support the above mentioned association. The clear association between GRB 170817A and AT 2017gfo has led to introduce a new model based on on a new subfamily of GRBs originating from WD-WD mergers. We show how this novel model is in agreement with the exceptional observations in the optical, infrared, X- and gamma-rays of GRB 170817A-AT 2017gfo.Comment: version accepted for publication in JCAP. Missing references adde

Plantas Alimentícias Não Convencionais & Saúde.

Esta cartilha apresenta as principais PANC que podemos incluir em nossa alimentação, ressaltando seus benefícios à saúde e informações sobre as técnicas de cultivo e como usá-las na sua cozinha

Fatores de risco para a transmissao vertical do HIV-1 e a influencia da terapia antirretroviral (ARV) no desfecho gestacional

In the absence of intervention, the rate of vertical transmission of HIV can range from 15-45%. With the inclusion of antiretroviral drugs during pregnancy and the choice of delivery route this amounts to less than 2%. However ARV use during pregnancy has generated several questions regarding the adverse effects of the gestational and neonatal outcome. This study aims to analyze the risk factors for vertical transmission of HIV-1 seropositive pregnant women living in Rio Grande and the influence of the use of ARVs in pregnancy outcome. Among the 262 pregnant women studied the rate of vertical transmission of HIV was found to be 3.8%. Regarding the VT, there was a lower risk of transmission when antiretroviral drugs were used and prenatal care was conducted at the referral service. However, the use of ART did not influence the outcome of pregnancy. However, initiation of prenatal care after the first trimester had an influence on low birth weight, as well as performance of less than six visits increased the risk of prematurity. Therefore, the risk factors analyzed in this study appear to be related to the realization of inadequate pre-natal and maternal behavior.Na ausência de intervenção, as taxas de transmissão vertical do HIV podem variar de 15-45%. Com a inserção dos antirretrovirais durante a gestação e a escolha da via de parto estas taxas chegam a menos de 2%. No entanto o uso de ARV na gestação tem gerado várias duvidas quanto aos efeitos adversos causados ao desfecho gestacional e ao neonato. Este estudo objetiva analisar os fatores de risco da transmissão vertical do HIV-1 em gestantes soropositivas atendidas na cidade do Rio Grande e a influência do uso do ARV no desfecho gestacional. Entre as 262 gestantes estudadas a taxa de transmissão vertical do HIV encontrada foi de 3,8%. Em relação à TV, foi observado menor risco de transmissão quando esta havia feito uso de antirretrovirais e o pré-natal era realizado no serviço de referência. Entretanto, o uso de ARV não influenciou negativamente o desfecho gestacional. No entanto, o inicio do pré-natal após o primeiro trimestre teve influencia sobre o baixo peso ao nascer, assim como a realização de menos de seis consultas aumentou o risco de prematuridade. Portanto, os fatores de risco analisados neste estudo parecem estar relacionados à realização não adequada do pré-natal e ao comportamento materno

A Geometric Variational Approach to Bayesian Inference

We propose a novel Riemannian geometric framework for variational inference in Bayesian models based on the nonparametric Fisher-Rao metric on the manifold of probability density functions. Under the square-root density representation, the manifold can be identified with the positive orthant of the unit hypersphere in L2, and the Fisher-Rao metric reduces to the standard L2 metric. Exploiting such a Riemannian structure, we formulate the task of approximating the posterior distribution as a variational problem on the hypersphere based on the alpha-divergence. This provides a tighter lower bound on the marginal distribution when compared to, and a corresponding upper bound unavailable with, approaches based on the Kullback-Leibler divergence. We propose a novel gradient-based algorithm for the variational problem based on Frechet derivative operators motivated by the geometry of the Hilbert sphere, and examine its properties. Through simulations and real-data applications, we demonstrate the utility of the proposed geometric framework and algorithm on several Bayesian models

Barras de cereais contendo alto teor de proteína de soja e isoflavonas na avaliação do perfil lipídico de indivíduos dislipidêmicos.

A dislipidemia é um problema de saúde pública devido a sua estreita relação com doenças cardiovasculares. A partir disso, estratégias farmacológicas e não-farmacológicas têm sido aplicadas. Entre elas está o desenvolvimento de alimentos funcionais que visem modificação do perfil lipídico. A ANVISA permite a alegação: O consumo diário de no mínimo 25 g de proteína de soja pode ajudar a reduzir o colesterol. O objetivo deste trabalho foi desenvolver um alimento tipo barra de cereais, contendo basicamente ingredientes derivados de soja e utilizá-lo em estudo clínico com indivíduos dislipidêmicos, para avaliar o efeito sobre o perfil lipídico, glicose e índices antropométricos. METODOLOGIA: Foram feitos inúmeros testes em laboratório de combinações dos ingredientes de soja (flocos, proteína texturizada, proteína isolada e soja torrada natural) até atingir características sensoriais desejáveis e no mínimo 25 g de proteína e ± 80 mg de isoflavonas em 100g de produto. Foi coletado sangue, antes e após 45 dias de consumo de 3 barras de soja/dia, de 25 indivíduos com colesterol total (CT) >200 mg/dL ou TG> 150 mg/dL e maiores de 18 anos. As análises de CT, HDL, TG e glicose foram realizadas utilizando metodologia automatizada. O LDL foi calculado. Foram medidos circunferência abdominal, peso, altura, para cálculo do IMC. RESULTADOS: Obteve-se barras de soja com ±30 g de proteína e ±100 mg de isoflavonas em 100g de produto. Não houve diminuição significativa (p0,05) nos parâmetros avaliados. No entanto, houve uma tendência de diminuição do nível de TG (±13%) e aumento do HDL (± 7%) após 45 dias de consumo. CONCLUSÃO: É possível produzir barras de soja com alto teor de proteínas e isoflavonas. Seus efeitos sobre o perfil lipídico devem ser estudados por mais tempo e população maior, pois apresentaram ótimas tendências de regularização dos níveis de TG e HDL