New coupled quintessence cosmology

A component of dark energy has been recently proposed to explain the current acceleration of the Universe. Unless some unknown symmetry in Nature prevents or suppresses it, such a field may interact with the pressureless component of dark matter, giving rise to the so-called models of coupled quintessence. In this paper we propose a new cosmological scenario where radiation and baryons are conserved, while the dark energy component is decaying into cold dark matter (CDM). The dilution of CDM particles, attenuated with respect to the usual $a^{-3}$ scaling due to the interacting process, is characterized by a positive parameter $\epsilon$, whereas the dark energy satisfies the equation of state $p_x=\omega \rho_x$ ($\omega < 0$). We carry out a joint statistical analysis involving recent observations from type Ia supernovae, baryon acoustic oscillation peak, and Cosmic Microwave Background shift parameter to check the observational viability of the coupled quintessence scenario here proposed.Comment: 7 pages, 7 figures. Minor corrections to match published versio

Low-energy neutrinos at off-axis from a standard beta-beam

We discuss a scenario to extract up to 150 MeV neutrinos at a standard beta-beam facility using one and two detectors off-axis. In particular we show that the high-energy component of the neutrino fluxes can be subtracted through a specific combination of the response of two off-axis detectors. A systematic analysis of the neutrino fluxes using different detector geometries is presented, as well as a comparison with the expected fluxes at a low-energy beta-beam facility. The presented option could offer an alternative way to perform low-energy neutrino experiments.Comment: 9 pages, 6 figure

Is the transition redshift a new cosmological number?

Observations from Supernovae Type Ia (SNe Ia) provided strong evidence for an expanding accelerating Universe at intermediate redshifts. This means that the Universe underwent a transition from deceleration to acceleration phases at a transition redshift $z_t$ of the order unity whose value in principle depends on the cosmology as well as on the assumed gravitational theory. Since cosmological accelerating models endowed with a transition redshift are extremely degenerated, in principle, it is interesting to know whether the value of $z_t$ itself can be observationally used as a new cosmic discriminator. After a brief discussion of the potential dynamic role played by the transition redshift, it is argued that future observations combining SNe Ia, the line-of-sight (or "radial") baryon acoustic oscillations, the differential age of galaxies, as well as the redshift drift of the spectral lines may tightly constrain $z_t$, thereby helping to narrow the parameter space for the most realistic models describing the accelerating Universe.Comment: 12 pages, 5 figures. Some discussions about how to estimate the transition redshift have been added. New data by Planck and H(z) data have been mentioned. New references have been adde

Mosca-da-carambola.

Mosca-da-carambola. Características. Hospedeiros. Inimigos naturais. Danos. Ações preventivas e de controle.bitstream/item/95908/1/CPAF-AP-2006-mosca-carambola.pd

Gerenciamento de riscos das nanotecnologias: aplicações do método GMP-RAM ao ciclo PDCA.

Resumo: Apesar dos nanomateriais já estarem presentes em grandes linhas de Pesquisa e Desenvolvimento e à disposição dos consumidores, ainda não existem metodologias consolidadas para o Gerenciamento de Risco associado ao ciclo de vida e ao uso intensivo desses novos materiais. Neste cenário, o presente trabalho propõe o emprego e adequação do Método GMP-RAM para o caso das nanotecnologias em diversas dimensões, associados ao ciclo PDCA para a avaliação, mitigação e minimização do risco encontrado. Dessa forma, pode-se concluir que as duas metodologias associadas são favoráveis para a quantificação do risco e tomadas de decisão por meio do plano de ação proposto, caso a caso