The Infrared-X-ray continuum correlation in Active Galactic Nuclei

The correlation between the soft X-ray and near infrared emission from AGN is analysed using composite models by the code SUMA. We find new evidences for differences in ranges of parameters which characterize the NLR of Seyfert galaxies and LINERs. Results obtained by modelling the Einstein and the ROSAT samples of galaxies are in full agreement. In order to fit the infrared and X-ray continua, an eta factor is defined, which accounts for the emitting area of the cloud. If the infrared emission is due to bremsstrahlung and comes from the same cloud producing the soft X-rays, the eta values obtained from both emissions must be the same. Therefore, if eta_IR < eta_soft-X there must be a strong contribution of soft X-rays from the active centre. From the eta values we expect to identify the objects that could present strong variability. \Comment: 11 pages,13 figures, in press in MNRAS. in press in MNRA

UV Continuum, Physical Conditions and Filling Factor in Active Galactic Nuclei

The narrow line region of active galaxies is formed by gas clouds surrounded by a diluted gas. Standard one-dimensional photoionization models are usually used to model this region in order to reproduce the observed emission lines. Since the narrow line region is not homogeneous, two major types of models are used: (a) those assuming a homogeneous gas distribution and a filling factor less than unity to mimic the presence of the emitting clouds; (b) those based on a composition of single-cloud models combined in order to obtain the observed spectra. The first method is largely used but may induce to misleading conclusions as shown in this paper. The second one is more appropriate, but requires a large number of observed lines in order to limit the number of single models used. After discussing the case of an extragalactic HII region, for which the ionizing radiation spectrum is better known, we show that 1-D models for the narrow line region with a filling factor less than unit do not properly mimic the clumpiness, but just simulates an overall lower density. Multi-cloud models lead to more reliable results. Both models are tested in this paper, using the emission-line spectra of two well-known Seyfert galaxies, NGC 4151 and NGC 1068. It is shown that ionizing radiation spectra with a blue bump cannot be excluded by multi-cloud models, although excluded by Alexander et al. (1999, 2000)using homogeneous models with a filling factor less than unity.Comment: 23 pages, 7 figures. Accepted for Publication in Ap

Vitamin K as a diet supplement with impact in human health: current evidence in age-related idseases

Vitamin K health benefits have been recently widely shown to extend beyond blood homeostasis and implicated in chronic low-grade inflammatory diseases such as cardiovascular disease, osteoarthritis, dementia, cognitive impairment, mobility disability, and frailty. Novel and more efficient nutritional and therapeutic options are urgently needed to lower the burden and the associated health care costs of these age-related diseases. Naturally occurring vitamin K comprise the phylloquinone (vitamin K1), and a series of menaquinones broadly designated as vitamin K2 that differ in source, absorption rates, tissue distribution, bioavailability, and target activity. Although vitamin K1 and K2 sources are mainly dietary, consumer preference for diet supplements is growing, especially when derived from marine resources. The aim of this review is to update the reader regarding the specific contribution and effect of each K1 and K2 vitamers in human health, identify potential methods for its sustainable and cost-efficient production, and novel natural sources of vitamin K and formulations to improve absorption and bioavailability. This new information will contribute to foster the use of vitamin K as a health-promoting supplement, which meets the increasing consumer demand. Simultaneously, relevant information on the clinical context and direct health consequences of vitamin K deficiency focusing in aging and age-related diseases will be discussed.info:eu-repo/semantics/publishedVersio

Occupational exposure to Aflatoxin B1 in Portuguese swine farms

In 1987, the International Agency for Research on Cancer concluded that there was sufficient evidence for carcinogenicity of naturally occurring aflatoxins in humans. Regarding occupational exposure to this chemical agent, farmers and other agricultural workers present a higher risk due to airborne aflatoxin via inhalation of dust. This study was carried out in 7 swine farms located at the district of Lisbon, Portugal. Blood samples were collected from a total of 11 workers. In addition, a control group (n = 25) was included that conducted administrative tasks in an educational institution without any type of agricultural activity. Results obtained suggest that occupational exposure to AFB1 by inhalation occurs and represents an additional risk in this occupational setting that need to be recognized, assessed and, most important, prevented

An assessment and application of turbulence models for hypersonic flows

The current approach to the Accurate Computation of Complex high-speed flows is to solve the Reynolds averaged Navier-Stokes equations using finite difference methods. An integral part of this approach consists of development and applications of mathematical turbulence models which are necessary in predicting the aerothermodynamic loads on the vehicle and the performance of the propulsion plant. Computations of several high speed turbulent flows using various turbulence models are described and the models are evaluated by comparing computations with the results of experimental measurements. The cases investigated include flows over insulated and cooled flat plates with Mach numbers ranging from 2 to 8 and wall temperature ratios ranging from 0.2 to 1.0. The turbulence models investigated include zero-equation, two-equation, and Reynolds-stress transport models

Experiments in square lattice with a common treatment in all blocks

O Instituto Agronômico de Campinas vem, há muitos anos, utilizando, nos seus ensaios de milho, reticulados quadrados com k² tratamentos em blocos de k + 1 parcelas, sendo a parcela extra de cada bloco cultivada com um cultivar padrão (variedade ou híbrido), não incluído entre os k² tratamentos originais. Conclui-se, pois, que esses delineamentos incluem k² + 1 tratamentos, em blocos de k + 1 parcelas. O presente trabalho deduz fórmulas para a análise da variância desses delineamentos, e para a estimação das médias ajustadas de tratamentos. Fórmulas para a variância de diversos contrastes são deduzidas. Finalmente, apresenta-se um exemplo, detalhadamente analisado, de um ensaio em reticulado quadrado com k² = 25, e 4 repetições ortogonais, instalado corn 26 cultivares, em blocos de 6 parcelas.This paper deals with a generalization of square lattice designs, with k² treatments in blocks of k + 1 plots, the extra plot in each block receiving a standard treatment, the same for all blocks. The new design leads to lower variances for contrasts between adjusted treatment mean

Benchmarking of Monte Carlo Flux simulations of electrons in CO2

Electron velocity distribution functions (EVDFs) in CO2 obtained by means of the Monte Carlo Flux (MCF) method are compared with results from two-term and multi-term Boltzmann solvers. The MCF method provides detailed calculations of the EVDF through a highly efficient variance reduction technique. Benchmark calculations of Legendre polynomial coefficients of the EVDF expansion are reported for a wide range of reduced electric fields (E/N), showing excellent agreement with multi-term solutions. Rate coefficients of inelastic processes calculated from two-term Boltzmann solvers differ significantly, up to 70%, from MCF and multi-term solutions, due to the anisotropy of the EVDF. An extension of the method to consider the thermal distribution of the background gas is also presented. This extension, together with an accurate description of the population of rotationally and vibrationally excited states, provides excellent agreement with measured transport coefficients at low E/N. A good agreement is obtained at moderate E/N between experimental values of dissociation rate coefficients and MCF calculations after careful consideration and analysis of several cross sections data sets.</p

Benchmarking of Monte Carlo flux simulations of electrons in CO2

Electron velocity distribution functions (EVDFs) in CO2 obtained by means of the Monte Carlo flux (MCF) method are compared with results from two-term and multi-term Boltzmann solvers. The MCF method provides detailed calculations of the EVDF through a highly efficient variance reduction technique. Benchmark calculations of Legendre polynomial coefficients of the EVDF expansion are reported for a wide range of reduced electric fields (E/N), showing excellent agreement with multi-term solutions. Rate coefficients of inelastic processes calculated from two-term Boltzmann solvers differ significantly, up to 70%, from MCF and multi-term solutions, due to the anisotropy of the EVDF. An extension of the method to consider the thermal distribution of the background gas is also presented. This extension, together with an accurate description of the population of rotationally and vibrationally excited states, provides excellent agreement with measured transport coefficients at low E/N. A good agreement is obtained at moderate E/N between experimental values of dissociation rate coefficients and MCF calculations after careful consideration and analysis of several cross sections data sets