The effect of radial migration on galactic disks

We study the radial migration of stars driven by recurring multi-arm spiral features in an exponential disk embedded in a dark matter halo. The spiral perturbations redistribute angular momentum within the disk and lead to substantial radial displacements of individual stars, in a manner that largely preserves the circularity of their orbits and that results, after 5 Gyr (~40 full rotations at the disk scalelength), in little radial heating and no appreciable changes to the vertical or radial structure of the disk. Our results clarify a number of issues related to the spatial distribution and kinematics of migrators. In particular, we find that migrators are a heavily biased subset of stars with preferentially low vertical velocity dispersions. This "provenance bias" for migrators is not surprising in hindsight, for stars with small vertical excursions spend more time near the disk plane and thus respond more readily to non-axisymmetric perturbations. We also find that the vertical velocity dispersion of outward migrators always decreases, whereas the opposite holds for inward migrators. To first order, newly arrived migrators simply replace stars that have migrated off to other radii, thus inheriting the vertical bias of the latter. Extreme migrators might therefore be recognized, if present, by the unexpectedly small amplitude of their vertical excursions. Our results show that migration, understood as changes in angular momentum that preserve circularity, can affect strongly the thin disk, but cast doubts on models that envision the Galactic thick disk as a relic of radial migration.Comment: 10 pages, 12 figures. ApJ in pres

El progresismo pedagógico y el libro de texto.

Sin resume

Corruption scandals, press reporting, and accountability. Evidence from Spanish mayors.

We analyse the effects of local corruption on electoral outcomes with Spanish data. Based upon press reports published between 1996 and 2009, we are able to construct a novel database on corruption scandals and news related to bribe-taking in exchange for amendments to land use plans. Our data show that local corruption scandals first emerged during the 1999-2003 term, but that they peaked just before the 2007 elections. We estimate an equation for the incumbents vote share at this electoral contest and find the average vote loss after a corruption scandal to be around 4%, and the effect to be greater for cases receiving wide newspaper coverage (up to 9%). The effects found for the 2003 elections are much lower. When we consider cases in which the incumbent has been charged with corruption and press coverage has been extensive the vote loss can rise to 12%. However, press reports have a negative impact on the vote even when no judicial charges have been brought.voting, corruption, accountability

Corruption scandals, press reporting, and accountability. Evidence from Spanish mayors

We analyse the effects of local corruption on electoral outcomes with Spanish data. Based upon press reports published between 1996 and 2009, we are able to construct a novel database on corruption scandals and news related to bribe-taking in exchange for amendments to land use plans. Our data show that local corruption scandals first emerged during the 1999-2003 term, but that they peaked just before the 2007 elections. We estimate an equation for the incumbent’s vote share at this electoral contest and find the average vote loss after a corruption scandal to be around 4%, and the effect to be greater for cases receiving wide newspaper coverage (up to 9%). The effects found for the 2003 elections are much lower. When we consider cases in which the incumbent has been charged with corruption and press coverage has been extensive the vote loss can rise to 12%. However, press reports have a negative impact on the vote even when no judicial charges have been brought.voting, accountability, corruption

Physiological Plasticity of Neural-Crest-Derived Stem Cells in the Adult Mammalian Carotid Body

Adult stem cell plasticity, or the ability of somatic stem cells to cross boundaries and differentiate into unrelated cell types, has been amatter of debate in the last decade. Neural-crest-derived stem cells (NCSCs) display a remarkable plasticity during development. Whether adult populations of NCSCs retain this plasticity is largely unknown. Herein, we describe that neural-crest-derived adult carotid body stem cells (CBSCs) are able to undergo endothelial differentiation in addition to their reported role in neurogenesis, contributing to both neurogenic and angiogenic processes taking place in the organ during acclimatization to hypoxia. Moreover, CBSC conversion into vascular cell types is hypoxia inducible factor (HIF) dependent and sensitive to hypoxiareleased vascular cytokines such as erythropoietin. Our data highlight a remarkable physiological plasticity in an adult population of tissue-specific stem cells and could have impact on the use of these cells for cell therapy.ERC Starting Grant: CBSCsMinisterio de Economía y Competitividad SAF2013-48535-P and SAF2016-80412-

Análisis de las redes sociales en el Servicio de Deportes del Campus María Zambrano

ste trabajo es un análisis de información y los gustos de los usuarios de las redes sociales del Servicio de Deportes, con el fin de conocer el camino por el que debe seguir para mejorar sus objetivos y llegar a conocer lo que los usuarios quieren recibir del servicio.Grado en Publicidad y Relaciones Pública

Low Speed Re-Fuelling of Unmanned Aerial Vehicles Using the Drogue System

Unmanned Aerial Vehicles (UAV) are being required to be used in more and more complex situations with larger payloads for extended periods of time. Increasing the expectations and operating ceiling requires increased amounts fuel, that thus limits the potential payloads. This dichotomy has led to the quest for more fuel efficient UAVs; however, when designs are improved then their expectations are increased further. In manned aircraft this can be achieved by in-flight re-fuelling. This research is focused on the process of re-fuelling a UAV at low speeds and the aerodynamics considerations and problems it potentially brings. Practical conclusions to these concerns are addressed and recommendations for future research are identified

Do Mergers Spin up Dark Matter Halos?

We use a large cosmological N-body simulation to study the origin of possible correlations between the merging history and spin of cold dark matter halos. In particular, we examine claims that remnants of major mergers tend to have higher-than-average spins, and find that the effect is driven largely by unrelaxed systems: equilibrium dark matter halos show no significant correlation between spin and merger history. Out-of-equilibrium halos have, on average, higher spins than relaxed systems, suggesting that the virialization process leads to a net decrease in the value of the spin parameter. We find that this decrease is driven by the internal redistribution of mass and angular momentum that occurs during virialization, a process that is especially efficient during major mergers, when high angular momentum material is pushed beyond the virial radius of the remnant. Since such redistribution likely affects the angular momentum of baryons and dark matter unevenly, our findings question the common practice of identifying the specific angular momentum content of a halo with that of its embedded luminous component. Further work is needed to elucidate the true relation between the angular momentum content of baryons and dark matter in galaxy systems assembled hierarchically.Comment: Accepted for publication in MNRAS Letters, 5 pages, 3 figures. One table and more statistical tests added but conclusions are unchange

Cognitive Plasticity in Young-Old Adults and Old-Old Adults and Its Relationship with Successful Aging

The general objective of this study was to analyze cognitive plasticity as a variable related to successful aging in a group of young-old adults and old-old adults using the Auditory Verbal Learning Test—Learning Potential (AVLT-LP). Method: A total of 569 persons, with mean age 76.67 years (379 between the ages of 65 and 80 years, and 190 older than age 80). They were assessed with a socio-health questionnaire, with the AVLT-LP, and with the Spanish version of the Mini Mental State Examination. Results: The results showed significant differences on the test, in favor of the younger group, while the over 80 group gave poorer performance and showed less cognitive plasticity. With relation to gender, slight differences appeared in favor of the women, on the first four test trials, but not on the last two, nor in delayed recall or cognitive plasticity. As for cognitive status, the results showed significantly better task performance levels in healthy elders, as well as greater plasticity. Nonetheless, certain persons with high plasticity were also found among those with cognitive impairment. Conclusions: The data obtained here offers evidence for the importance of cognitive plasticity in elders and its relation to longevity and successful aging. It also provides information about the influence of variables like age, gender and cognitive status on a verbal memory and plasticity assessment task that is in wide use today