Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties

Understanding the nature of spiral structure in disk galaxies is one of the main, and still unsolved questions in galactic astronomy. However, theoretical works are proposing new testable predictions whose detection is becoming feasible with recent development in instrumentation. In particular, streaming motions along spiral arms are expected to induce azimuthal variations in the chemical composition of a galaxy at a given galactic radius. In this letter we analyse the gas content in NGC 6754 with VLT/MUSE data to characterise its 2D chemical composition and H$\alpha$ line-of-sight velocity distribution. We find that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of tangentially-slower, radially-outward (tangentially-faster, radially-inward) streaming motions of metal-rich (poor) gas over a large range of radii. These results show direct evidence of gas radial migration for the first time. We compare our results with the gas behaviour in a $N$-body disk simulation showing spiral morphological features rotating with a similar speed as the gas at every radius, in good agreement with the observed trend. This indicates that the spiral arm features in NGC 6754 may be transient and rotate similarly as the gas does at a large range of radii.Comment: 8 pages, 4 figures, accepted for publication in ApJL 2016 September 2

A Framework to Evaluate Software Developer’s Productivity The VALORTIA Project

Currently, there is a lack in companies developing software in relation to assessing their staff’s productivity before executing software projects, with the aim of improving effectiveness and efficiency. QuEF (Quality Evaluation Framework) is a framework that allows defining quality management tasks based on a model. The main purpose of this framework is twofold: improve an entity’s continuous quality, and given a context, decide between a set of entity’s instances on the most appropriate one. Thus, the aim of this paper is to make this framework available to evaluate productivity of professionals along software development and select the most appropriate experts to implement the suggested project. For this goal, Valortia platform, capable of carrying out this task by following the QuEF framework guidelines, is designed. Valortia is a platform to certify users' knowledge on a specific area and centralize all certification management in its model by means of providing protocols and methods for a suitable management, improving efficiency and effectiveness, reducing cost and ensuring continuous quality.Ministerio de Ciencia e Innovación TIN2013-46928-C3-3-

Formation of asymmetric arms in barred galaxies

ABSTRACTWe establish a dynamical mechanism to explain the origin of the asymmetry between the arms observed in some barred disc galaxies, where one of the two arms emanating from the bar ends is very well defined, while the second one displays a ragged structure, extending between its ridge and the bar. To this purpose, we study the invariant manifolds associated with the Lyapunov periodic orbits around the unstable equilibrium points at the ends of the bar. Matter from the galaxy centre is transported along these manifolds to the periphery, forming this way the spiral arms that emanate from the bar ends. If the mass distribution in the galaxy centre is not homogeneous, because of an asymmetric bar with one side stronger than the other, or because of a non-centred bulge, the dynamics about the two unstable Lagrange points at the ends of the bar will not be symmetric as well. One of their invariant manifolds becomes more extended than the other, enclosing a smaller section and the escaping orbits on it are fewer and dispersed in a wider region. The result is a weaker arm and more ragged than the one at the other end of the bar

Coherent carrier dynamics in semiconductor superlattices

We investigate the coherent dynamics of carriers in semiconductor superlattices driven by ac-dc electric fields. We solve numerically the time-dependent effective-mass equation for the envelope function. We find that carriers undergo Rabi oscillations when the driving frequency is close to the separation between minibands.Comment: REVTEX (6 pages) and 3 figures (PostScript). Accepted in Physics Letters

Corso, un buldog con ansiedad por separación

Se describe un caso de ansiedad por separación en un Buldog Francés macho de 1,7 años de edad. Sus dueños acuden a la consulta, ya que Corso destroza todo cuando se queda solo en casa. En un primer momento fue el salón, en donde fue necesario realizar obras de reparación de los destrozos provocados por el paciente. En la actualidad es un pasillo, su nueva ubicación cuando está solo. El tratamiento se compuso de tres partes: terapia farmacológica consistente en Trankimazin 1mg 1/24h y Fluoxetina 20mg 1/24h, la modificación de su entorno y una modificación de conducta, facilitada por el propio tratamiento farmacológico. Siete meses después, tras varios seguimientos, Corso es dado el alta, prolongándole el tratamiento farmacológico de Fluoxetina, media dosis durante un mes más.Privateering is described to a case of separation anxiety in a French Bulldog of 1,7 years, called Corso. The owners go to the clinic because Corso destroys everything when left alone at home. Initially was the living room where they had to make repairs of damage caused by Corso. Currently is a corridor, its new location when left alone. Treatment consisted of three parts: first the pharmacological treatment Trankimazin 1mg 1/24h and Fluoxetina 20mg 1/24h, then changing his environment and also a behavior modification helped by the pharmalogical treatment. Seven months later, and after several follow-ups, Corso was medical discharged but the pharmacological treatment was maintained for a month with half dose of Fluoxetina

On the source of Faraday rotation in the jet of the radio galaxy 3C120

The source of Faraday rotation in the jet of the radio galaxy 3C120 is analyzed through Very Long Baseline Array observations carried out between 1999 and 2007 at 86, 43, 22, 15, 12, 8, 5, 2, and 1.7 GHz. Comparison of observations from 1999 to 2001 reveals uncorrelated changes in the linear polarization of the underlying jet emission and the Faraday rotation screen: while the rotation measure (RM) remains constant between approximately 2 and 5 mas from the core, the RM-corrected electric vector position angles (EVPAs) of two superluminal components are rotated by almost 90 degrees when compared to other components moving through similar jet locations. On the other hand, the innermost 2 mas experiences a significant change in RM -- including a sign reversal -- but without variations in the RM-corrected EVPAs. Similarly, observations in 2007 reveal a double sign reversal in RM along the jet, while the RM-corrected EVPAs remain perpendicular to the jet axis. Although the observed coherent structure and gradient of the RM along the jet supports the idea that the Faraday rotation is produced by a sheath of thermal electrons that surrounds the emitting jet, the uncorrelated changes in the RM and RM-corrected EVPAs indicate that the emitting jet and the source of Faraday rotation are not closely connected physically and have different configurations for the magnetic field and/or kinematical properties. Furthermore, the existence of a region of enhanced RM whose properties remain constant over three years requires a localized source of Faraday rotation, favoring a model in which a significant fraction of the RM originates in foreground clouds.Comment: 12 pages, 11 figures; Accepted for publication in Ap

Random Topologies and the emergence of cooperation: the role of short-cuts

We study in detail the role of short-cuts in promoting the emergence of cooperation in a network of agents playing the Prisoner's Dilemma Game (PDG). We introduce a model whose topology interpolates between the one-dimensional euclidean lattice (a ring) and the complete graph by changing the value of one parameter (the probability p to add a link between two nodes not already connected in the euclidean configuration). We show that there is a region of values of p in which cooperation is largely enhanced, whilst for smaller values of p only a few cooperators are present in the final state, and for p \rightarrow 1- cooperation is totally suppressed. We present analytical arguments that provide a very plausible interpretation of the simulation results, thus unveiling the mechanism by which short-cuts contribute to promote (or suppress) cooperation

Tourism, Competitiveness and Economic Growth: A New Analytical Model

This study reviews the theories relating to competitiveness and the indicators used for its measurement on the one hand and the studies that relate tourism and growth on the other, with the purpose of establishing the links that exist between both concepts. This enables a model to be defined in which some factors that affect tourism competitiveness combine with capital and work to determine economic growth. The provision of inherited tourism resources, together with the provision of productive resources, and the links between them are the determining elements of the capacity of an economy to produce and therefore to grow

Methodology for the damage assessment of vehicles exposed to flooding in urban areas

Within urban areas, humans carry out a great diversity of activities, and some of them require the use of vehicles. Floods, especially in urban areas, can generate significant tangible direct damages to vehicles themselves and to the urban elements in case of loss of stability and collision, which cannot be dismissed. In this paper, after a state-of-the-art review on damage curves for vehicles, a methodology to assess the direct economic impact for vehicles exposed to flooding has been described, and applied within a study carried out in the framework of the BINGO H2020 EU Project. Only three different studies focused on damages to vehicles in contact with floodwater have been found. Contrasting damage curves for vehicles are found when comparing the three approaches, however, the ones proposed by the U.S. Army Corps of Engineers (USACE) offer a high level of completeness and accuracy. Moreover, USACE''s development is the most current research and all the steps for the development of the damage curves are comprehensively described. Finally, after the description of a detailed methodology for flood damage mapping for vehicles, a procedure to evaluate the Expected Annual Damage for vehicles is offered