Brownian motion of black holes in stellar systems with non-Maxwellian distribution for the stars field

A massive black hole at the center of a dense stellar system, such as a globular cluster or a galactic nucleus, is subject to a random walk due gravitational encounters with nearby stars. It behaves as a Brownian particle, since it is much more massive than the surrounding stars and moves much more slowly than they do. If the distribution function for the stellar velocities is Maxwellian, there is a exact equipartition of kinetic energy between the black hole and the stars in the stationary state. However, if the distribution function deviates from a Maxwellian form, the strict equipartition cannot be achieved. The deviation from equipartition is quantified in this work by applying the Tsallis q-distribution for the stellar velocities in a q-isothermal stellar system and in a generalized King model.Comment: Presented at XXVI Int. Astronomical Union General Assembly, Symp. 238, Prague, Czech Republic, Aug 21-25 200

Gravity with extra dimensions and dark matter interpretation: A straightforward approach

Any connection between dark matter and extra dimensions can be cognizably evinced from the associated effective energy-momentum tensor. In order to investigate and test such relationship, a higher dimensional spacetime endowed with a factorizable general metric is regarded to derive a general expression for the stress tensor -- from the Einstein-Hilbert action -- and to elicit the effective gravitational potential. A particular construction for the case of six dimensions is provided, and it is forthwith revealed that the missing mass phenomenon may be explained, irrespective of the dark matter existence. Moreover, the existence of extra dimensions in the universe accrues the possibility of a straightforward mechanism for such explanation. A configuration which density profile coincides with the Newtonian potential for spiral galaxies is constructed, from a 4-dimensional isotropic metric plus extra-dimensional components. A Miyamoto-Nagai \emph{ansatz} is used to solve Einstein equations. The stable rotation curves associated to such system are computed, in full compliance to the observational data, without fitting techniques. The density profiles are reconstructed and compared to that ones obtained from the Newtonian potential.Comment: 13 pages, 6 figure

Multi-messenger particles as a probe for UHECR luminosity

Very-high energy (GeV-TeV) gamma rays in the universe suggest the presence of an accelerator in the source. Neutrinos and gamma rays are intriguing astrophysical messengers. Multi-messenger particle emission produced by interactions of cosmic rays with radiation fields and interstellar matter is a probe of luminosity of sources of cosmic rays with EeV energies, known as Ultra-High Energy Cosmic Rays (UHECRs). This work estimates the neutrino flux and suggests that gamma-ray emission is primarily caused by cosmic-ray interactions during propagation. As energy loss processes occur, secondary fluxes are generated, primarily by pion decay. We provide UHECR luminosity of galaxies from multi-messenger particles. These findings not only highlight the potential of certain galaxies as sources of UHECR, but also underscore the intricate interplay of various astrophysical processes within them. By understanding the luminosity patterns and multi-messenger particle emissions, we can gain valuable insights into the environmental conditions, acceleration mechanisms, and other intrinsic properties that position these galaxies as candidates for UHECR production.Comment: 10 pages, 4 figure

Hybrid fruits for Improving health—A comprehensive review.

Several species of hybrid fruits, such as citrus, grapes, blueberries, apples, tomatoes, and lingonberries among others, have attracted scientific attention in recent years, especially due to their reported antioxidant and anti-inflammatory properties. The bagasse, leaves, bark, and seeds of these hybrid fruits have large amounts of polyphenols, such as flavonoids, which act as potent antioxidants. Several studies have been carried out in cellular models of neurotoxicity of the extract of these fruits, to document the beneficial effects for human health, as well as to prove its antiproliferative effect in cancer cells. In the present review, through a synthesis of existing information in the scientific literature, we demonstrate that hybrid fruits are a source of antioxidant and bioactive compounds, which act in the inhibition of diseases such as cancer, diabetes, and inflammatory and neurodegenerative diseases, and consequently improving human health.artigo n. 219

Características espectrais da radiação solar em Igarapé-Açu, PA: variáveis associadas a respostas biológicas.

São apresentados resultados preliminares da caracterização espectral da radiação solar na região nordeste do Estado do Pará, realizada mediante espectroradiômetro portátil (LI-1800, Li-Cor), no município de Igarapé-Açu, PA. São abordadas as seguintes variáveis, que interferem de modo diferenciado em processos de crescimento e desenvolvimento em plantas: radiação ultravioleta A (UV-A); radiação ativa ao pigmento azul (RAA); radiação ativa na fotossíntese (RAF); radiação no infra-vermelho próximo (IVP); e razão vermelho/vermelho extremo (V:Ve). Foi observado que, dentro de cada faixa espectral estudada, há pouca variabilidade ao longo do ano, em sua contribuição relativa à radiação total, sendo apenas observadas variações marcantes em seus valores absolutos. V:Ve exibiu valores crescentes acompanhando classes de irradiância total (IT), variando entre 1,28 (±0,03) para IT400 W m-2.Disponível o artigo completo em CD