Deflationary Models Driven by Matter Creation

A nonsingular deflationary cosmology driven by adiabatic matter creation is proposed. In this scenario there is no preinflationary stage as happens in conventional inflationary models. Deflation starts from a de Sitter spacetime characterized by an arbitrary time scale $H_{I}^{-1}$, which also pins down an initial value for the temperature of the universe. The model evolves continuously towards a slightly modified Friedman-Robertson-Walker universe. The horizon and other well known problems of the standard model are then solved but, unlike in microscopic models of inflation, there is no supercooling and subsequent reheating. Entropy generation is concomitant with deflation and if $H_{I}^{-1}$ is of the order of the Planck time, the present day value of the radiation temperature is deduced. It is also shown that the ``age problem'' does not exist here. In particular, the theoretically favored FRW flat model is old enough to agree with the observations even given the high values of $H_{o}$ suggested by recent measurements.Comment: 17 pages, 2 figures(available from the authors), uses LATE

Periódicos de Oporto, públicos de la ciudad : la construcción de la identidad editorial y las audiencias

The three Oporto daily newspapers O Comércio do Porto, O Primeiro de Janeiro and Jornal de Notícias were founded during the XIX century and steadily grew in prestige and respect amongst the national Portuguese press. These papers began as local and ideological projects supported by political parties and a powerful commercial association but gradually evolved to more comprehensive newspapers with a wider range of lectors. Each particular profile was built through editorial policies which led to strategies of audience identification, underlined by the charisma of their owners and directors. The aim of this study is to identify the engagement processes with readers in their early days and the methodology will rely on sources such as newspapers contents and some other specialized publications. The key moments of evolution in Comércio, Janeiro and Notícias will be tracked by the adaptation to the modernization challenges according to reports, newspapers and some senior journalists’ testimoniesLos periódicos de Oporto O Comércio do Porto, O Primeiro de Janeiro y Jornal de Notícias, surgieron en el siglo XIX y gradualmente se tornaron títulos nacionales de prestigio. Inicialmente dos de ellos eran proyectos ideológicos de partidos políticos locales y el tercero tenía el respaldo de la asociación comercial, pero con el tiempo fueron evolucionando hacia modelos de información más anchos, ampliando el círculo de lectores. El perfil informativo de cada uno se construyó en articulación con públicos específicos y a través de la promoción de procesos de identificación, reforzada por la acción de propietarios y directores carismáticos. El objetivo de este estudio es identificar estas características editoriales y procesos de conquista del público en sus primeras etapas, según una metodología basada en el contenido de los periódicos y publicaciones especializadas. Los momentos clave de la transformación serán identificados por los periódicos, informes y testimonios de periodista

Ising model with spins S=1/2 and 1 on directed and undirected Erd\"os-R\'enyi random graphs

Using Monte Carlo simulations we study the Ising model with spin S=1/2 and 1 on {\it directed} and {\it undirected} Erd\"os-R\'enyi (ER) random graphs, with $z$ neighbors for each spin. In the case with spin S=1/2, the {\it undirected} and {\it directed} ER graphs present a spontaneous magnetization in the universality class of mean field theory, where in both {\it directed} and {\it undirected} ER graphs the model presents a spontaneous magnetization at $p = z/N$ ($z=2, 3, ...,N$), but no spontaneous magnetization at $p = 1/N$ which is the percolation threshold. For both {\it directed} and {\it undirected} ER graphs with spin S=1 we find a first-order phase transition for z=4 and 9 neighbors.Comment: 11 pages, 8 figure