Model Atmospheres for Irradiated Giant Stars: Implications for the Galactic Center

Irradiation of a stellar atmosphere by an external source (e.g. an AGN) changes its structure and therefore its spectrum. Using a state-of-the-art stellar atmosphere code, we calculate the infrared spectra of such irradiated and transformed stars. We show that the original spectrum of the star, which is dominated by molecular bands, changes dramatically when irradiated even by a low-luminosity AGN ($L_{\rm X} = 10^{33}$ erg s$^{-1}$), becoming dominated by atomic lines in absorption. We study the changes in the spectrum of low-mass carbon- and oxygen-rich giant stars as they are irradiated by a modest AGN, similar to the one at the Galactic center (GC). The resulting spectra are similar to those of the faintest S-cluster stars observed in the GC. The spectrum of a star irradiated by a much brighter AGN, like that powered by a tidally disrupted star, is very different from that of any star currently observed near the GC. For the first time we have discovered that the structure of the atmosphere of an irradiated giant changes dramatically and induces a double inversion layer. We show that irradiation at the current level can explain the observed trend of CO band intensities decreasing as a function of increasing proximity to Sg $A^{*}$. This may indicate that (contrary to previous claims) there is no paucity of old giants in the GC, which coexist simultaneously with young massive stars.Comment: Submitted to ApJ; typo in name correcte

Dark energy, non-minimal couplings and the origin of cosmic magnetic fields

In this work we consider the most general electromagnetic theory in curved space-time leading to linear second order differential equations, including non-minimal couplings to the space-time curvature. We assume the presence of a temporal electromagnetic background whose energy density plays the role of dark energy, as has been recently suggested. Imposing the consistency of the theory in the weak-field limit, we show that it reduces to standard electromagnetism in the presence of an effective electromagnetic current which is generated by the momentum density of the matter/energy distribution, even for neutral sources. This implies that in the presence of dark energy, the motion of large-scale structures generates magnetic fields. Estimates of the present amplitude of the generated seed fields for typical spiral galaxies could reach $10^{-9}$ G without any amplification. In the case of compact rotating objects, the theory predicts their magnetic moments to be related to their angular momenta in the way suggested by the so called Schuster-Blackett conjecture.Comment: 5 pages, no figure

Application of the response surface method to optimize alkali activated cements based on low-reactivity ladle furnace slag

Steel-making slags, resulting from basic oxygen furnaces or electric arc furnaces are heavily applied in the construction industry, as an aggregate for pavements or concrete. Although possessing a significant crystalline content, it is expected that, if properly milled, the reactivity of these slags can increase up to a point when they are viable to produce alkaline cements. The aim of this study was the application of a response surface method to design the experimental work required to optimise the composition of an alkaline cement based on ladle furnace slag, a specific type of steel slag (SG). Fly ash (FA) was also added, in a precursor role, and the activation was achieved with an alkaline solution prepared with sodium silicate (SS) and sodium hydroxide (SH). The factors/variables considered were the activator index X = SS/(SS + SH), the precursor index Y = SG/(SG + FA) and the SH concentration (Z). The output variables were the unconfined compression strength and the flexural strength, after 7 and 28 days curing. Results indicate that the activator index (X) was the most influential variable, followed by the precursor index (Y). Microstructural analysis of selected pastes was also performed, using scanning electron microscopy and energy dispersive spectroscopy. The ideal composition obtained for the alkaline cement was the mixture constituted by X = 0.75, Y = 0.5 and Z = 10 (activator: 75% SS and 25% SH; precursor: 50% SG and 50% FA; SH concentration = 10 molal). This mixture achieved 8.70 MPa of flexural strength and 44.25 MPa of compressive strength which is reasonable for the required application (soil stabilisation)

SpikingLab: modelling agents controlled by Spiking Neural Networks in Netlogo

The scientific interest attracted by Spiking Neural Networks (SNN) has lead to the development of tools for the simulation and study of neuronal dynamics ranging from phenomenological models to the more sophisticated and biologically accurate Hodgkin-and-Huxley-based and multi-compartmental models. However, despite the multiple features offered by neural modelling tools, their integration with environments for the simulation of robots and agents can be challenging and time consuming. The implementation of artificial neural circuits to control robots generally involves the following tasks: (1) understanding the simulation tools, (2) creating the neural circuit in the neural simulator, (3) linking the simulated neural circuit with the environment of the agent and (4) programming the appropriate interface in the robot or agent to use the neural controller. The accomplishment of the above-mentioned tasks can be challenging, especially for undergraduate students or novice researchers. This paper presents an alternative tool which facilitates the simulation of simple SNN circuits using the multi-agent simulation and the programming environment Netlogo (educational software that simplifies the study and experimentation of complex systems). The engine proposed and implemented in Netlogo for the simulation of a functional model of SNN is a simplification of integrate and fire (I&F) models. The characteristics of the engine (including neuronal dynamics, STDP learning and synaptic delay) are demonstrated through the implementation of an agent representing an artificial insect controlled by a simple neural circuit. The setup of the experiment and its outcomes are described in this work

Methane aromatization in a fluidized bed reactor: Parametric study

Methane aromatization is a promising technology for the transformation of natural gas into liquid products, but suffers from the problem of catalyst deactivation by coke. A two-zone fluidized bed reactor has been proposed as a tool to counteract the catalyst deactivation, by providing continuous catalyst regeneration in the same vessel where the main reaction is carried out. This work shows the effect of the main operating conditions (carburization temperature, reaction temperature, carburization time, nature of regenerating agent and feed flow and height of the hydrocarbon entry point). Optimal reduction time and temperature were 1 h and 350°C. Best conversion and selectivity were achieved at 700°C without catalyst deactivation in the TZFBR

A formação acadêmica de pessoas com deficiência nas escolas públicas do Estado de Goiás, para que esta seja inserida no mercado de trabalho.

O presente estudo teve por objetivo analisar a educação inclusiva do Colégio Estadual Felismina Cardoso Batista, localizado no município de Campos Belos – Goiás, especificamente no tocante a Formação Acadêmica de Pessoas com Deficiência para que estas sejam Inseridas no Mercado de Trabalho. A educação é um direito assegurado na Constituição Federal brasileira para todos os alunos, que deve ser assegurada pelas redes de ensino, sem nenhum tipo de distinção. A problemática fundamentou-se em analisar se as práticas pedagógicas utilizadas para atender aos educandos com deficiência contribuem na formação dos mesmos para que estes sejam inseridos no mercado de trabalho. Tivemos como apoio teórico estudiosos que fazem referência ao tema dessa pesquisa. Para atender aos objetivos e ao problema investigativo, elencamos o enfoque qualitativo tipo descritivo como meio de analise para chegar ao resultado. Os participantes desse estudo foram os professores regentes de sala de aula, coordenadores, gestor e professores de apoio a educação inclusiva. Também contribuiu com essa pesquisa as Secretários Municipais de Educação e de Saúde e três empresários do município de Campos Belos – Goiás. Ademais, os resultados obtidos apontam para a necessidade de uma organização nas ações de formação continuada dos professores, principalmente no que tange a aplicação de práticas pedagógicas diferenciadas que possam de fato favorecer a aprendizagem dos educandos com deficiência

Altered circadian rhythm and metabolic gene profile in rats subjected to advanced light phase shifts

The circadian clock regulates metabolic homeostasis and its disruption predisposes to obesity and other metabolic diseases. However, the effect of phase shifts on metabolism is not completely understood. We examined whether alterations in the circadian rhythm caused by phase shifts induce metabolic changes in crucial genes that would predispose to obesity. Three-month-old rats were maintained on a standard diet under lighting conditions with chronic phase shifts consisting of advances, delays or advances plus delays. Serum leptin, insulin and glucose levels decreased only in rats subjected to advances. The expression of the clock gene Bmal 1 increased in the hypothalamus, white adipose tissue (WAT), brown adipose tissue (BAT) and liver of the advanced group compared to control rats. The advanced group showed an increase in hypothalamic AgRP and NPY mRNA, and their lipid metabolism gene profile was altered in liver, WAT and BAT. WAT showed an increase in inflammation and ER stress and brown adipocytes suffered a brown-to-white transformation and decreased UCP-1 expression. Our results indicate that chronic phase advances lead to significant changes in neuropeptides, lipid metabolism, inflammation and ER stress gene profile in metabolically relevant tissues such as the hypothalamus, liver, WAT and BAT. This highlights a link between alteration of the circadian rhythm and metabolism at the transcriptional level

Protein malnutrition impairs the immune response and influences the severity of infection in a hamster model of chronic visceral leishmaniasis

Leishmaniasis remains one of the world's most devastating neglected tropical diseases. It mainly affects developing countries, where it often co-exists with chronic malnutrition, one of the main risk factors for developing the disease. Few studies have been published, however, on the relationship between leishmaniasis progression and malnutrition. The present paper reports the influence of protein malnutrition on the immune response and visceral disease development in adult hamsters infected with Leishmania infantum fed either standard or low protein diets. The low protein diet induced severe malnutrition in these animals, and upon infection with L. infantum 33% had severe visceral leishmaniasis compared to only 8% of animals fed the standard diet. The infected, malnourished animals showed notable leukocyte depletion, mild specific antibody responses, impairment of lymphoproliferation, presence of parasites in blood (16.67% of the hamsters) and significant increase of the splenic parasite burden. Animals fed standard diet suffered agranulocytosis and monocytopenia, but showed stronger specific immune responses and had lower parasite loads than their malnourished counterparts. The present results show that protein malnutrition promotes visceral leishmaniasis and provide clues regarding the mechanisms underlying the impairment of the immune system.This work was funded by project PI10/00829 from the Fondo de Investigación Sanitaria, http://www.isciii.es/. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.S