Effect of the Canting of Local Anisotropy Axes on Ground-State Properties of a Ferrimagnetic Chain with Regularly Alternating Ising and Heisenberg Spins

The effect of the canting of local anisotropy axes on the ground-state phase diagram and magnetization of a ferrimagnetic chain with regularly alternating Ising and Heisenberg spins is exactly examined in an arbitrarily oriented magnetic field. It is shown that individual contributions of Ising and Heisenberg spins to the total magnetization basically depend on the spatial orientation of the magnetic field and the canting angle between two different local anisotropy axes of the Ising spins.Comment: 3 pages, 3 figure

H\"older mean applied to Anderson localization

The phase diagram of correlated, disordered electron systems is calculated within dynamical mean-field theory using the H\"older mean local density of states. A critical disorder strength is determined in the Anderson-Falicov-Kimball model and the arithmetically and the geometrically averages are found to be just particular means used respectively to detect or not the Anderson localization. Correlated metal, Mott insulator and Anderson insulator phases, as well as coexistence and crossover regimes are analyzed in this new perspective.Comment: 6 pages, 6 figures: Phys. Rev. B 76, 035111 (2007

Mercado e comercialização na ovinocultura de corte no Brasil.

Resumo: O objetivo deste artigo é apresentar os dados relativos ao mercado e à comercialização da carne ovina no Brasil. Especificamente destacam-se os principais estados produtores, a questão da importação, os preços praticados, a estrutura agrária brasileira como um fator significativo para análise deste setor produtivo e o mercado internacional da ovinocultura. Para tanto são utilizados dados do Instituto Brasileiro de Geografia e Estatística, da Organização das Nações Unidas para Agricultura e Alimentação e outras fontes secundárias especializadas no setor. Os países com o maior rebanho ovino no mundo são China, Índia e Austrália, respectivamente, e a produção de carne ovina está concentrada majoritariamente no continente asiático (52%). Os dados demonstram que o Brasil possui o rebanho ovino concentrado em alguns estados da região Nordeste e no Rio Grande do Sul, os preços aos produtores têm se mantido estáveis no último ano com uma leve tendência de alta, que há uma tendência para o desenvolvimento da indústria de abate e de processamento e, como consequência, uma aproximação ao mercado consumidor. No entanto, conclui-se que persistem entraves organizacionais que impedem o desenvolvimento do setor e que precisam ser superados com urgência. Abstract: The aim of this paper is to present data on the market and the commercialization of sheep meat in Brazil. Specifically we highlight the major producing states, the issue of importation, the prices, the Brazilian agrarian structure as a significant factor for the analysis of this sector and the international market. To achieve this goal, the data were provided by the Brazilian Institute of Geography and Statistics and by the United Nations Food and Agriculture and other specialized secondary sources. Countries with the largest sheep flock in the world are China, India and Australia, respectively, and the meat production is mainly concentrated in Asia (52%). The data show that Brazilian sheep flock are concentrated in a few states in the Northeast and Rio Grande do Sul, the producer prices have remained stable over the last year with a slight upward trend, there is a tendency for the development of slaughter and processing industry and, as a consequence, an approximation to the consumer market. However, it is concluded that organizational obstacles remain and hinder the development of the sector and they must be overcome urgently

Detectability of the First Cosmic Explosions

We present a fully self-consistent simulation of a synthetic survey of the furthermost cosmic explosions. The appearance of the first generation of stars (Population III) in the Universe represents a critical point during cosmic evolution, signaling the end of the dark ages, a period of absence of light sources. Despite their importance, there is no confirmed detection of Population III stars so far. A fraction of these primordial stars are expected to die as pair-instability supernovae (PISNe), and should be bright enough to be observed up to a few hundred million years after the big bang. While the quest for Population III stars continues, detailed theoretical models and computer simulations serve as a testbed for their observability. With the upcoming near-infrared missions, estimates of the feasibility of detecting PISNe are not only timely but imperative. To address this problem, we combine state-of-the-art cosmological and radiative simulations into a complete and self-consistent framework, which includes detailed features of the observational process. We show that a dedicated observational strategy using $\lesssim 8$ per cent of total allocation time of the James Webb Space Telescope mission can provide us up to $\sim 9-15$ detectable PISNe per year.Comment: 9 pages, 8 figures. Minor corrections added to match published versio

Using gamma regression for photometric redshifts of survey galaxies

Machine learning techniques offer a plethora of opportunities in tackling big data within the astronomical community. We present the set of Generalized Linear Models as a fast alternative for determining photometric redshifts of galaxies, a set of tools not commonly applied within astronomy, despite being widely used in other professions. With this technique, we achieve catastrophic outlier rates of the order of ~1%, that can be achieved in a matter of seconds on large datasets of size ~1,000,000. To make these techniques easily accessible to the astronomical community, we developed a set of libraries and tools that are publicly available.Comment: Refereed Proceeding of "The Universe of Digital Sky Surveys" conference held at the INAF - Observatory of Capodimonte, Naples, on 25th-28th November 2014, to be published in the Astrophysics and Space Science Proceedings, edited by Longo, Napolitano, Marconi, Paolillo, Iodice, 6 pages, and 1 figur