Inertial waves in rapidly rotating flows: a dynamical systems perspective

An overview of recent developments in a wide variety of enclosed rapidly rotating flows is presented. Highlighted is the interplay between inertial waves, which have been predicted from linear inviscid considerations, and the viscous boundary layer dynamics which result from instabilities as the nonlinearities in the systems are increased. Further, even in the absence of boundary layer instabilities, nonlinearity in the system often leads to complicated interior flows due to subcritical instabilities, Eckhaus bands and heteroclinic dynamics. The ensuing spatio-temporally complex dynamics is analysed in terms of equivariant dynamical systems, providing a general perspective for the wide range of dynamics involved.Postprint (author's final draft

Social Mobility and Demand for Redistribution. A Comparative Analysis

The literature on preferences for redistribution has paid little attention to the effect of social mobility on the demand for redistribution, which is in contrast with the literature on class-voting, where studies on the effect of social mobility has been very common. Some works have addressed this issue but no systematic test of the hypotheses connecting social mobility and preferences has been done. In this paper we use the diagonal reference models to estimate the effect of origin and destination class on preferences for redistribution in a sample of European countries using data from the European Social Survey. Our findings indicate that social origin matters to a little extent to explain preferences, as newcomers tend to adopt the preferences of the destination class. Moreover, we have found only limited evidence supporting the acculturation hypothesis and not support for the status maximization hypothesis. Furthermore, the effect of social origin varies largely between countries. In a second step of the analysis we investigate what are the national factors explaining this variation. The empirical evidence we present leads to conclude that high rates of upward social mobility sharply reduce the effect of social origin on preferences for redistributionUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Small aspect ratio Taylor-Couette flow: onset of a very-low-frequency three-torus state

The nonlinear dynamics of Taylor-Couette flow in a small aspect ratio annulus (where the length of the cylinders is half of the annular gap between them) is investigated by numerically solving the full three-dimensional Navier-Stokes equations. The system is invariant to arbitrary rotations about the annulus axis and to a reflection about the annulus half-height, so that the symmetry group is SO(2)×Z2. In this paper, we systematically investigate primary and subsequent bifurcations of the basic state, concentrating on a parameter regime where the basic state becomes unstable via Hopf bifurcations. We derive the four distinct cases for the symmetries of the bifurcated orbit, and numerically find two of these. In the parameter regime considered, we also locate the codimension-two double Hopf bifurcation where these two Hopf bifurcations coincide. Secondary Hopf bifurcations (Neimark-Sacker bifurcations), leading to modulated rotating waves, are subsequently found and a saddle-node-infinite-period bifurcation between a stable (node) and an unstable (saddle) modulated rotating wave is located, which gives rise to a very-low-frequency three-torus. This paper provides the computed example of such a state, along with a comprehensive bifurcation sequence leading to its onset.Postprint (published version

Nonlinear and detuning effects of the nutation angle in precessionally-forced rotating cylinder flow

The flow in a rapidly rotating cylinder forced to precess through a nutation angle a is investigated numerically, keeping all parameters constant except a, and tuned to a triadic resonance at a = 1º. When increasing a, the flow undergoes a sequence of well- characterized bifurcations associated with triadic resonance, involving heteroclinic and homoclinic cycles, for a up to about 4º. For larger a, we identify two chaotic regimes. In the first regime, with a between about 4º and 27º, the bulk flow retains remnants of the helical structures associated with the triadic resonance, but there are strong nonlinear interactions between the various azimuthal Fourier components of the flow. For the larger a regime, large detuning effects lead to the triadic resonance dynamics being completely swamped by boundary layer eruptions. The azimuthal mean flow at large angles results in a large mean deviation from solid-body rotation and the flow is characterized by strong shear at the boundary layers with temporally chaotic eruptions.Postprint (author's final draft

La circulación monetaria en los territorios interiores del norte de la península ibérica durante los primeros años del alto imperio romano

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Public employment and regional redistribution in Spain

We study the determinants, beyond the process of decentralisation, of the regional allocation of public jobs by the Central Government and the increase in the number of public employees at the Regional Governments in Spain during 1990-1999. Using standard panel data econometric procedures we show that the Central Government might have been increasing the number of public jobs in those regions with lower levels of GDP per capita. Also we show that the number of public employees is larger in those regions in which there has been a coincidence between the political orientation of the ruling parties in the Regional and Central Governments. Finally, we find that political variables might explain part of the increase in the number of public employees in the Regional Governments, together with the process of decentralisation and GDPpc.Public Employment; Regional Redistribution; Fiscal Policy Instruments

Una Experiencia de enseñanza centrada en el aprendizaje

En este trabajo presentamos una experiencia de implantación de una asignatura combinando diversas metodologías de aprendizaje activo: flipped classroom con JiTT (Just in Time Teaching), uso del portafolio reflexivo y autoevaluación. Los resultados obtenidos demuestran que este tipo de metodologías favorecen la implicación del alumno en su aprendizaje de manera continua, permitiéndole adquirir las competencias de la asignatura. Además, una correcta planificación de las actividades les permite abordarlas en el tiempo previsto para la asignatura y no sobrecarga de trabajo al profesorado incluso con grupos numerosos. Los resultados parciales disponibles de la evaluación continua son muy positivos, así como la opinión de los alumnos sobre la metodología y su propio aprendizaje.SUMMARY -- In this work we describe the implementation of a course that combines several active learning methodologies: flipped classroom with JiTT (Just in Time Teaching), reflective portfolio and self-assessment. Our results show that the use of this kind of methodologies benefits the continuous involvement of the students in their learning process, allowing them to achieve the competences of the course. Besides, a correct planning of the activities permits the students to approach them in the expected time and does not increase the workload of professors, even when working with large groups. Only partial results of the continuous assessment process are available, but they are very positive, as well as the opinions collected from students about the methodology and their own learning process

Roadmap for optical tweezers

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAMOptical tweezers are tools made of light that enable contactless pushing, trapping, and manipulation of objects, ranging from atoms to space light sails. Since the pioneering work by Arthur Ashkin in the 1970s, optical tweezers have evolved into sophisticated instruments and have been employed in a broad range of applications in the life sciences, physics, and engineering. These include accurate force and torque measurement at the femtonewton level, microrheology of complex fluids, single micro- and nano-particle spectroscopy, single-cell analysis, and statistical-physics experiments. This roadmap provides insights into current investigations involving optical forces and optical tweezers from their theoretical foundations to designs and setups. It also offers perspectives for applications to a wide range of research fields, from biophysics to space explorationEuropean Commission (Horizon 2020, Project No. 812780

Financial innovation for a sustainable economy

Climate change and its management and mitigation are unquestionably among the main risks facing our society in the coming decades. The financial sector plays a key role in this challenge, firstly because of its exposure and the consequent capital shocks if this risk crystallises, and secondly because it has the task of financing the investments needed to transform our economy into a sustainable one. This article reviews various initiatives under way in the private financial sector to introduce the variable “sustainability” into its decision-making process in order to achieve a balance sheet with a smaller carbon footprint (transformation of stock) and to develop a business strategy aligned with responsible investment principles and international standards (transformation of flow). We analyse the innovations emerging along the path to sustainable finance, looking particularly at: 1) new suppliers and services in the market, 2) the creation of sustainability-linked financial instruments, 3) the adaptation of financial risk management policies, and 4) the interaction of technological progress with climate change.El cambio climático, su gestión y mitigación, constituye sin duda uno de los elementos de riesgo más importantes que afrontará nuestra sociedad en las próximas décadas. El sector financiero desempeña un papel fundamental en este reto, tanto por su exposición y las consiguientes implicaciones patrimoniales que pueden derivarse de la materialización de este riesgo como por su labor canalizando las inversiones necesarias para transformar nuestra economía en un modelo sostenible. En este artículo se revisan distintas iniciativas que están teniendo lugar en el sector financiero privado en el proceso de introducción de la variable «sostenibilidad» en la toma de decisiones, con el objetivo tanto de lograr un balance con una menor huella de carbono (transformación del stock) como de desarrollar una estrategia de negocio alineada con unos principios responsables acordes con los compromisos internacionales (transformación del flujo). Se analizan las innovaciones que están surgiendo en el camino hacia unas finanzas sostenibles en relación con 1) la aparición de nuevos proveedores y servicios en los mercados, 2) la creación de nuevos productos financieros con criterios de sostenibilidad, 3) la adaptación de la política de gestión de riesgos financieros, y 4) las interacciones entre los avances tecnológicos y el cambio climático