The Evolution of the Baryon Distribution in the Universe from Cosmological Simulations

The evolution of the baryon distribution in different phases, derived from cosmological simulations, are here reported. These computations indicate that presently most of baryons are in a warm-hot intergalactic (WHIM) medium (about 43%) while at z = 2.5 most of baryons constitute the diffuse medium (about 74%). Stars and the cold gas in galaxies represent only 14% of the baryons at z = 0. For z < 4 about a half of the metals are locked into stars while the fraction present in the WHIM and in the diffuse medium increases with a decreasing redshift. In the redshift range 0 < z < 2.5, the amount of metals in the WHIM increases from 4% to 22% while in the diffuse medium it increases from 0.6% to 4%. This enrichment process is due essentially to a turbulent diffusion mechanism associated to mass motions driven by supernova explosions. At z = 0, simulated blue (late type) galaxies show a correlation of the oxygen abundance present in the cold gas with the luminosity of the considered galaxy that agrees quite well with data derived from HII regions.Comment: 12 pages, 6 figures, to be published in IJMP

Evolution of the Phase-Space Density of Dark Matter Halos and Mixing Effects in Merger Events

Cosmological N-body simulations were performed to study the evolution of the phase-space density Q = rho/sigma^3 of dark matter halos. No significant differences in the scale relations Q ~ sigma^(-2.1) or Q ~ M^(-0.82) are seen for "cold" or "warm" dark matter models. The follow up of individual halos from z = 10 up to the present time indicate the existence of two main evolutionary phases: an early and fast one (10 > z > 6.5), in which Q decreases on the average by a factor of 40 as a consequence of the randomization of bulk motions and a late and long one (6.5 > z > 0), in which Q decreases by a factor of 20 because of mixing induced by merger events. The study of these halos has also evidenced that rapid and positive variations of the velocity dispersion, induced by merger episods, are related to a fast decrease of the phase density Q.Comment: 6 pages, accepted by MNRA

The elastoplastic analysis of planar frames for large displacements by mathematical programming

Imperial Users onl

Cost accounting vs. throughput accounting: answer to the lean production's demands

A produção enxuta tem provocado mudanças significativas nas empresas, mudanças estas que não vêm sendo acompanhadas pelos sistemas de gestão econômica, desenvolvidos sobre pressupostos equivocados da produção em massa que defendem que as otimizações locais isoladas resultam na otimização global da empresa. Deste modo, pode-se afirmar que a contabilidade de custos não é capaz de prover as informações necessárias à correta tomada de decisão nas empresas enxutas. Por outro lado, constata-se uma coerência entre os princípios da produção enxuta e os pressupostos que sustentam a contabilidade de ganhos da Teoria das Restrições. Sendo assim, o objetivo deste artigo é apresentar argumentos que respaldem estas afirmações, bem como justifiquem a necessidade da utilização da contabilidade de ganhos como base teórica para a proposta de um método de gestão econômica para a produção enxuta.Lean production has provoked significant changes in companies. These changes have not being followed by the economic management systems, which are developed based on mistaken assumptions made by mass production which argues that isolated local optimizations can lead to the global optimization of the company. In this way, it can be affirmed that cost accounting cannot provide the necessary information for decision making in lean companies. On the other hand, consistency is evidenced between the principles of the lean production and the assumptions that support the throughput accounting of the Theory of Constraints. Therefore, the objective of this article is to present arguments that corroborate these assertions and justify the necessity for the use of the throughput accounting as a theoretical basis for the proposal of an economic management method for lean production.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES

On the cosmological effects of the Weyssenhoff spinning fluid in the Einstein-Cartan framework

The effects of non-Riemannian structures in Cosmology have been studied long ago and are still a relevant subject of investigation. In the seventies, it was discovered that singularity avoidance and early accelerated expansion can be induced by torsion in the Einstein-Cartan theory. In this framework, torsion is not dynamical and is completely expressed by means of the spin sources. Thus, in order to study the effects of torsion in the Einstein-Cartan theory, one has to introduce matter with spin. In principle, this can be done in several ways. In this work we consider the cosmological evolution of the universe in the presence of a constant isotropic and homogeneous axial current and the Weyssenhoff spinning fluid. We analyse possible solutions of this model, with and without the spinning fluid.Comment: Work presented at the 7th Alexander Friedmann International Seminar on Gravitation and Cosmology, Joao Pessoa, Brazil, 29 Jun - 5 Jul 2008. No figures, 5 pages. New version with dynamical equation corrected, new reference and a brief comparison with its experimental bound

First record of the Bicoloured-spined Porcupine Coendou bicolor (Tschudi, 1844) for Brazil

While travelling as part of the protected area management activities undertaken by the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio) in the state of Acre, four records of porcupines (Coendou spp.) were gathered: two for Coendou bicolor and two for Coendou prehensilis. The records for Coendou bicolor are the first for Brazil while the records for Coendou prehensilis present the state of Acre as a potential region of sympatry between C. bicolor and C. prehensilis

Selection and application of graphical and numerical statistical tools by prospective primary school teachers

Teaching statistics in the early years requires that teachers at this school level develop skills to analyze small collections of data. Given a collection of quantitative data (12 observations), in this paper we looked at how students and prospective primary school teachers select and make appropriate graphs and identify and determine statistical measures suitable for summarizing the data, including the interpretation of the third quartile. The study involved 50 students who were attending the 2nd year of the Basic Education Bachelor’s program at a university in northern Portugal. The collected data correspond to the answers given by the students in a formal examination in a Probability and Statistics course. An analysis of the answers showed that the students had difficulties in both the selection and application of statistical methods, which were more pronounced when they had to identify the appropriate graphs to represent the data and to determine the quartiles and to interpret the third quartile, and less pronounced in the case of determining other statistical measures

Inflation Targeting in Brazil: Shocks, Backward-Looking Prices, and IMF Conditionality

This paper examines the recent evolution of monetary policy since the adoption of formal inflation targeting in Brazil. We argue that the new policy framework has been subject to a severe test in its first years of existence, represented by external shocks - oil prices, and increased international financial volatility. Moreover, we examine some selected issues that deserve due consideration given their importance to the conduct of monetary policy. The first issue is the presence of a substantial portion of prices with backward-looking adjustment, a fact that affects monetary policy reaction since it reduces the efficiency of domestic interest rates in controlling inflation. The second addresses the question of how inflation targets should be monitored in a country that has an ongoing economic program with the International Monetary Fund. This last issue is particularly important when considering the effects of shortening monitoring horizons on the variability of inflation and output.