Understanding chemical evolution in resolved galaxies -- I The local star fraction-metallicity relation

This work studies the relation between gas-phase oxygen abundance and stellar-to-gas fraction in nearby galaxies. We first derive the theoretical prediction, and argue that this relation is fundamental, in the sense that it must be verified regardless of the details of the gas accretion and star formation histories. Moreover, it should hold on "local" scales, i.e. in regions of the order of 1 kpc. These predictions are then compared with a set of spectroscopic observations, including both integrated and resolved data. Although the results depend somewhat on the adopted metallicity calibration, observed galaxies are consistent with the predicted relation, imposing tight constraints on the mass-loading factor of (enriched) galactic winds. The proposed parametrization of the star fraction-metallicity relation is able to describe the observed dependence of the oxygen abundance on gas mass at fixed stellar mass. However, the "local" mass-metallicity relation also depends on the relation between stellar and gas surface densities.Comment: 10 pages, 4 figures. Matches accepted version (significant typo corrected

An intrinsic Proper Generalized Decomposition for parametric symmetric elliptic problems

We introduce in this paper a technique for the reduced order approximation of parametric symmetric elliptic partial differential equations. For any given dimension, we prove the existence of an optimal subspace of at most that dimension which realizes the best approximation in mean of the error with respect to the parameter in the quadratic norm associated to the elliptic operator, between the exact solution and the Galerkin solution calculated on the subspace. This is analogous to the best approximation property of the Proper Orthogonal Decomposition (POD) subspaces, excepting that in our case the norm is parameter-depending, and then the POD optimal sub-spaces cannot be characterized by means of a spectral problem. We apply a deflation technique to build a series of approximating solutions on finite-dimensional optimal subspaces, directly in the on-line step. We prove that the partial sums converge to the continuous solutions, in mean quadratic elliptic norm.Comment: 18 page

Linking tourism, retirement migration and social capital

A general trend in the study of international retirement migration has been the increased attention paid to the social contacts and network connections of the migrants in both the destination and the origin areas. These studies have examined the extent to which migrants build social relationships with their neighbours and the host society while also maintaining social links with their countries of origin, addressing the central role that leisure travel plays in sustaining increasingly dispersed social networks and maintaining the social capital of these networks and of the individuals involved in them. Using a case study approach to examine British retirement migration to Spain, we explore the relevance of transnational social networks in the context of international retirement migration, particularly the intensity of bidirectional visiting friends and relatives (VFR) tourism flows and the migrants' social contacts with friends and/or family back in their home country. Building on the concept of social capital and Putnam's distinction between bonding and bridging social capital, we propose a framework for the analysis of the migrants' international social networks. The results of a study conducted based on a sample of 365 British retirees living in the coast of Alicante (Spain) show both the strength of the retirees' international bonding social capital and the role of 'VFR's travel and communication technologies in sustaining the migrants' transnational social practices and, ultimately, their international bonding social capital. It also provides evidence for the reinforcing links between tourism-related mobility and amenity-seeking migration in later life. © 2013 © 2013 Taylor & Francis

New challenges for the definition of functional geographies

Studies from both Eurostat and the OECD shortly before the 2020/2021 Census ‘round’ concluded with one recommended approach to defining functional geographies (FGs). The question of which method to use in defining FGs for official statistics and policy has been superceded by challenging questions about the data to use for these definitions. One major concern stems from the decline of full Census-taking around the world, and in particular the reduced collection of the commuting data usually central to definitions of FGs. A more acute issue is that the 2020/2021 Census ‘round’ coincided with the Covid pandemic so that in many countries any commuting data collected reflects a brief and probably unique moment in time (eg. a total ‘lockdown’ in some countries). Defining FGs for official statistics and policy in the mid-2020s would ideally use data on ‘new normal’ patterns of commuting. Countries without a full register system or a new Census lack the necessary highly granular commuting data. This has led to increasing interest in the potential of call data from mobile phones as a surrogate for commuting data. This paper draws on research in Spain on the specific example of using data from mobiles to define a set of FGs. The approach taken is to evaluate the limits to the utility of mobile phone data by identifying a list of issues arising when using mobile phone data as a surrogate for Census commuting data, especially when seeking to define FGs

Homogenization of the one-dimensional wave equation

We present a method for two-scale model derivation of the periodic homogenization of the one-dimensional wave equation in a bounded domain. It allows for analyzing the oscillations occurring on both microscopic and macroscopic scales. The novelty reported here is on the asymptotic behavior of high frequency waves and especially on the boundary conditions of the homogenized equation. Numerical simulations are reported

Promoting dignified end-of-life care in the emergency department: a qualitative study

Background: Preservation of a dying person’s dignity in the emergency department (ED) is fundamental for the patient, his/her relatives and healthcare professionals. The aim of this study was to explore and interpret physicians’ and nurses’ experiences regarding conservation of dignity in end-of-life care in dying patients in the ED. Methods: A qualitative study based on the hermeneutic phenomenological approach, was carried out in the emergency department of two general hospitals. A total of 16 nurses and 10 physicians participated in the study. Data collection included 12 individual in-depth interviews and 2 focus groups. Results: The findings revealed that two themes represent the practices and proposals for the conservation of dignity in the emergency department: dignified care in hostile surroundings and the design of a system focused on the person’s dignity. Conclusion: Dignifying treatment, redesigning environmental conditions, and reorienting the healthcare system can contribute to maintaining dignity in end-of-life care in the ED

Nature or nurture? Clues from the distribution of specific star formation rates in SDSS galaxies

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reservedThis work investigates the main mechanism(s) that regulate the specific star formation rate (SSFR) in nearby galaxies, cross-correlating two proxies of this quantity -- the equivalent width of the \Ha\ line and the (u−r) colour -- with other physical properties (mass, metallicity, environment, morphology, and the presence of close companions) in a sample of ∼82500 galaxies extracted from the Sloan Digital Sky Survey (SDSS). The existence of a relatively tight `ageing sequence' in the colour-equivalent width plane favours a scenario where the secular conversion of gas into stars (i.e. `nature') is the main physical driver of the instantaneous SSFR and the gradual transition from a `chemically primitive' (metal-poor and intensely star-forming) state to a `chemically evolved' (metal-rich and passively evolving) system. Nevertheless, environmental factors (i.e. `nurture') are also important. In the field, galaxies may be temporarily affected by discrete `quenching' and `rejuvenation' episodes, but such events show little statistical significance in a probabilistic sense, and we find no evidence that galaxy interactions are, on average, a dominant driver of star formation. Although visually classified mergers tend to display systematically higher EW(Hα) and bluer (u−r) colours for a given luminosity, most galaxies with high SSFR have uncertain morphologies, which could be due to either internal or external processes. Field galaxies of early and late morphological types are consistent with the gradual `ageing' scenario, with no obvious signatures of a sudden decrease in their SSFR. In contrast, star formation is significantly reduced and sometimes completely quenched on a short time scale in dense environments, where many objects are found on a `quenched sequence' in the colour-equivalent width planeFinancial support has been provided by projects AYA2010-21887-C04-03 (former Ministerio de Ciencia e Innovación, Spain) and AYA2013-47742-C4-3-P (Ministerio de Economía y Competitividad), as well as the exchange programme ‘Study of Emission-Line Galaxies with Integral-Field Spectroscopy’ (SELGIFS, FP7-PEOPLE-2013-IRSES-612701), funded by the EU through the IRSES scheme. YA is also supported by the Ramón y Cajal programme (RyC-2011-09461), currently managed by the Ministerio de Economía y Competitividad (still cutting back on the Spanish scientific infrastructure

Inside the metropolis: the articulation of Spanish metropolitan areas into local labor markets

In this article, we delimit local labor markets (LLMs) in order to analyze the internal structure and organization of Spanish metropolitan areas. LLMs are defined as self-contained and cohesive areas in terms of commuting flows. Unlike the conventional approach to polycentrism based on the analysis of commuting flows that begins with the identification of subcenters, our analytical strategy does assume any a priori structure and is compatible with the relationship between places of work and residence having other locational and spatial organization patterns. The analysis is performed at three different scales of detail linked to three self-containment levels for the LLMs delimited and three population groups (total, males, and females). The results show that metropolitan areas are complex, fuzzy, multidimensional spaces, where the conditions of spatial organization are manifested in different ways depending on the parameters and variables used.This work was supported by the Spanish Ministry of Economy and Competitiveness [grant numbers CSO2011-29943-C03-01, CSO2011-29943-C03-02, CSO2014-55780-C3-1-P, and CSO2014-55780-C3-2-P (National R&D&I Plan)]