Accretion of Small Satellites and Gas Inflows in a Disc Galaxy

Galaxy interactions can have an important effect in a galaxy's evolution. Cosmological models predict a large number of small satellites around galaxies. It is important to study the effect that these small satellites can have on the host. The present work explores the effect of small N-body spherical satellites with total mass ratios in the range approx 1:1000-1:100 in inducing gas flows to the central regions of a disc galaxy with late-type morphology resembling the Milky Way. Two model galaxies are considered: barred and non-barred models; the latter one is motivated in order to isolate and understand better the effects of the satellite. Several circular and non-circular orbits are explored, considering both prograde and retrogade orientations. We show that satellites with such small mass ratios can still produce observable distortions in the gas and stellar components of the galaxy. In terms of gas flows, the prograde circular orbits are more favourable for producing gas flows, where in some cases up to $60% of the gas of the galaxy is driven to the central region. We find, hence, that small satellites can induce significant gas flows to the central regions of a disc galaxy, which is relevant in the context of fuelling active galactic nuclei.Comment: Accepted for publication in MNRA

The Impact of Unemployment on Individual Well-Being in the EU. CEPS ENEPRI Working Papers No. 29, 1 July 2004

Among the working-age population, one of the most damaging individual experiences is unemployment. Many previous studies have confirmed the devastating effects of unemployment on individual well-being, both pecuniary and non-pecuniary. Using the data from the European Community Household Panel survey, this paper examines the factors that affect unemployed workers’ well-being with respect to their situations in their main vocational activity, income, housing, leisure time and health in Europe. The research finds that unemployment substantially reduces an individual’s satisfaction levels with his or her main vocational activity and finance, while it greatly increases his or her satisfaction levels with leisure time. With respect to health, it has a small negative effect. Unemployment duration also has a small, negative impact on individual well-being, suggesting that unemployment has a lasting and aggravating effect throughout the spells of unemployment, contradicting the theory of adaptation

Nonlinear monetary policy rules: some new evidence for the US

This paper dreives optimal monetary policy rules in setups where certainty equivalence does not hold because either central bank preferences are not quadratic, and/or the aggregate supply relation is nonlinear. Analytical results show that these features lead to sign and size aymmetries, and nonlinearities in the policy rule. Reduced-form estimates indicate that US monetary policy can be characterized by a nonlinear policy rule after 1983, but not before 1979. This finding is consistent with the view that the Fed`s inflation preferences during the Volcker-Greenspan regime differ considerably from the ones during the Burns-Miller regime

Hybrid model predictive control for freeway traffic using discrete speed limit signals

HYCON2 Show day - Traffic modeling, Estimation and Control 13/05/2014 GrenobleIn this paper, two hybrid Model Predictive Control (MPC) approaches for freeway traffic control are proposed considering variable speed limits (VSL) as discrete variables as in current real world implementations. These discrete characteristics of the speed limits values and some necessary constraints for the actual operation of VSL are usually underestimated in the literature, so we propose a way to include them using a macroscopic traffic model within an MPC framework. For obtaining discrete signals, the MPC controller has to solve a highly non-linear optimization problem, including mixed-integer variables. Since solving such a problem is complex and difficult to execute in real-time, we propose some methods to obtain reasonable control actions in a limited computation time. The first two methods (-exhaustive and -genetic discretization) consist of first relaxing the discrete constraints for the VSL inputs; and then, based on this continuous solution and using a genetic or an exhaustive algorithm, to find discrete solutions within a distance of the continuous solution that provide a good performance. The second class of methods split the problem in a continuous optimization for the ramp metering signals and in a discrete optimization for speed limits. The speed limits optimization, which is much more time-consuming than the ramp metering one, is solved by a genetic or an exhaustive algorithm in communication with a non-linear solver for the ramp metering. The proposed methods are tested by simulation, showing not only a good performance, but also keeping the computation time reduced.Unión Europea FP7/2007–201

Climate refugees

The denomination of individuals affected by ecological migrations has often changed since the problem was first identified in 1985. In consideration of the subjective component, they are referred to as refugees, displaced persons or emigrant s; in consideration of the reason that triggers their displacement, they are named environmental, ecological or climatic. The nine variants which result from the combination of these two sets of words conform the standard terminology in the matter. In part icular, the use of the term ‘refugees’ seems to claim a correspondence with that of ‘political refugees’, and the adjective ‘climatic’ seems to impose a financial responsibility on the developed economies

La conciencia poética del lector adolescente, clave para la formación lectora

El autor de trabajo plantea la formación poética de los alumnos de educación secundaria obligatoria a partir de los textos que ellos mismos leen o escriben en distintos foros y soportes. Así mismo reflexiona sobre el papel que debe desempeñar la conciencia poética del adolescente para su formación lectora.The author aims at the role of the poetic consciousness in the formation of the teenager's reading. At the same time, he conceives that formation in high school education starting from the texts students produce and read in different situations and media

Industrial Change, Immigration, and Community Development: An Overview of Europeans and Latinos

The industrial forces and conditions of Massachusetts that awaited and attracted European immigrants were vastly different from those encountered by the more recent wave of Latino immigrants. This study seeks to compare and clarify what those forces and conditions were at three different times, especially in the small mill towns of Lowell, Lawrence, and Holyoke. The objective is to delineate a historical backdrop to allow an understanding of the present situation of Latinos in those cities and, to some extent, within the commonwealth of Massachusetts

Del no-lugar al cronotopos, pasando por el vestíbulo de la estación de Atocha

La estación de Atocha, por el sólo hecho de ser una estación de trenes, queda, teóricamente, dentro de la categoría que Marc Augé (1992/2000) designó como no-lugares. Augé (1992/2000) caracterizó los no-lugares como espacios carentes de historia e historias, imposibles de apropiar, que nacen de la sobremodernidad, período que comienza a finales del siglo pasado y que se caracteriza por una aceleración y exceso de acontecimientos, de espacios y un achicamiento del planeta. A través de la fotografía, asumiendo el punto de vista de Joan Fontcuberta (1990, 2009), hemos intentado buscar indicadores suficientes para entender la relación que hay entre un supuesto "no-lugar" y quienes lo transitan. Sin embargo, esta relación va más allá de una simple categoría. Hemos recurrido a la noción de cronotopos acuñada por Mijail Bajtín (1975/1989) y hemos intentado ofrecer otra mirada a las numerosas configuraciones que se pueden establecer entre las personas y los espacios. Hemos elaborado una tabla de Tipos de configuraciones espaciotemporales en un espacio concreto, en la que Cronotopoi (estables vs. efímeros) y Significación (lugar vs. no-lugar) se ponen en juego. A partir de esta tabla, hemos analizado algunos de los resultados que encontramos a lo largo de los casi cinco meses que estuvimos fotografiando el vestíbulo de Atocha y hemos hallado que las personas nos ubicamos en los espacios de diferentes modos, apropiándolos de formas peculiares que, como es lógico, van más allá de nuestras categorías de análisis.The Atocha station, by the mere fact of being a train station, is theoretically characterized by Marc Auge (1992/2000) as a non-place. Auge (1992/2000) characterizes these non-places as spaces devoid of any history or stories, impossible to appropriate, and that arise from supermodernity, a period that began at the end of the last century and is characterized by an acceleration and excess of events, spaces, and a shrinking of the planet. Through photography, according to Joan Fontcuberta's (1990, 2009) point of view, we have tried to find sufficient indicators in order to understand the relationship between a supposed "non-place" and the people that pass through it. However, this relationship goes beyond just a simple category. We have used the notion of chronotope, a concept introduced by Mikhail Bakhtin (1975/1989), in order to offer another point of view for the many configurations that can be established between people and spaces. We have developed a table of Types of Space-Time Configurations in a Specific Space, in which Chronotopoi (stable vs. ephermal) and Significance (non-place vs. place) are brought into play. From this table, we discuss some of the results found during the nearly five months that we were taking pictures of the Atocha station lobby, and we have found that people are located in spaces in different ways, appropriating in many peculiar ways, of course, beyond our categories of analysis