Explosive Synchronization Transitions in Scale-free Networks

The emergence of explosive collective phenomena has recently attracted much attention due to the discovery of an explosive percolation transition in complex networks. In this Letter, we demonstrate how an explosive transition shows up in the synchronization of complex heterogeneous networks by incorporating a microscopic correlation between the structural and the dynamical properties of the system. The characteristics of this explosive transition are analytically studied in a star graph reproducing the results obtained in synthetic scale-free networks. Our findings represent the first abrupt synchronization transition in complex networks thus providing a deeper understanding of the microscopic roots of explosive critical phenomena.Comment: 6 pages and 5 figures. To appear in Physical Review Letter

Consumo de alimentos de la población sonorense: tradición versus internacionalización

Las comidas tradicionales sonorenses y las comidas étnicas internacionales ya forman parte del bagaje gastronómico del consumidor regional. En esta investigación se busca conocer cuáles son las características y preferencias de consumo de ambos tipos de comida, a fin de establecer el posible efecto de desplazamiento de una sobre la otra. Para alcanzar este objetivo se ha efectuado un análisis de tipo exploratorio con base en un cuestionario de gustos y preferencias gastronómicas dirigido a consumidores. También se apoya en entrevistas a profundidad con amas de casa para identificar las comidas que se reconocen como típicas dentro del acervo culinario sonorense y aquellas que se consideran de reciente introducción. El estudio conforma uno de los primeros trabajos que analizan, en forma conjunta, las comidas étnicas internacionales y las comidas tradicionales sonorenses

Structure of Triadic Relations in Multiplex Networks

Recent advances in the study of networked systems have highlighted that our interconnected world is composed of networks that are coupled to each other through different "layers" that each represent one of many possible subsystems or types of interactions. Nevertheless, it is traditional to aggregate multilayer networks into a single weighted network in order to take advantage of existing tools. This is admittedly convenient, but it is also extremely problematic, as important information can be lost as a result. It is therefore important to develop multilayer generalizations of network concepts. In this paper, we analyze triadic relations and generalize the idea of transitivity to multiplex networks. By focusing on triadic relations, which yield the simplest type of transitivity, we generalize the concept and computation of clustering coefficients to multiplex networks. We show how the layered structure of such networks introduces a new degree of freedom that has a fundamental effect on transitivity. We compute multiplex clustering coefficients for several real multiplex networks and illustrate why one must take great care when generalizing standard network concepts to multiplex networks. We also derive analytical expressions for our clustering coefficients for ensemble averages of networks in a family of random multiplex networks. Our analysis illustrates that social networks have a strong tendency to promote redundancy by closing triads at every layer and that they thereby have a different type of multiplex transitivity from transportation networks, which do not exhibit such a tendency. These insights are invisible if one only studies aggregated networks.Comment: Main text + Supplementary Material included in a single file. Published in New Journal of Physic

Aprendizaje de conceptos complejos en Oceanografía a través del diseño de aplicaciones en Matlab: Una estrategia para motivar al alumnado e introducirlo en la programación

Este trabajo pretende resolver un problema detectado en el alumnado de la asignatura Oceanografía Física del Grado en Ciencias del Mar. Dicho problema está relacionado con la dificultad del alumnado actual para sentirse motivado ante el aprendizaje de conceptos complejos en Física, Química y Matemáticas así como adquirir las competencias y capacidades asociadas a dicho concepto. Se ha escogido un concepto complejo: la obtención del flujo geostrófico en el océano. El trabajo presenta un cuestionario inicial de evaluación previa tras la explicación del concepto en una clase magistral, el posterior desarrollo de una sesión de aprendizaje utilizando simulaciones virtuales y programación en Matlab así como un cuestionario final para evaluar el grado de satisfacción así como de adquisición de conocimientos y competencias tras realizar la actividad para así poder extraer conclusiones de su actividad. Aunque los cuestionarios y la sesión no se podrán aplicar hasta el curso académico 2016-17, esperamos que mejore significativamente el aprendizaje en clase, cree un ambiente favorable entre el alumnado para utilizar las nuevas tecnologías y la programación y pueda aplicarse posteriormente a otros conceptos de esta u otras asignaturas.Universidad de Alicant

Optimizing tip-surface interactions in ESR-STM experiments

Electron-spin resonance carried out with scanning tunneling microscopes (ESR-STM) is a recently developed experimental technique that is attracting enormous interest on account of its potential to carry out single-spin on-surface resonance with subatomic resolution. Here we carry out a theoretical study of the role of tip-adatom interactions and provide guidelines for choosing the experimental parameters in order to optimize spin resonance measurements. We consider the case of the Fe adatom on a MgO surface and its interaction with the spin-polarized STM tip. We address three problems: first, how to optimize the tip-sample distance to cancel the effective magnetic field created by the tip on the surface spin, in order to carry out proper magnetic field sensing. Second, how to reduce the voltage dependence of the surface-spin resonant frequency, in order to minimize tip-induced decoherence due to voltage noise. Third, we propose an experimental protocol to infer the detuning angle between the applied field and the tip magnetization, which plays a crucial role in the modeling of the experimental results.Comment: 10 pages, 5 Figure

Bibliografìa Argentina del género Prochilodus (Pisces: Curimatidae)

Fil: López, Hugo Luis. División Zoología Vertebrados, Museo de La Plata, UNLPFil: Bonetto, Argentino A.. Museo Argentino de Ciencias Naturales Bernardino Rivadavia; Buenos AiresFil: Gómez, Sergio E.. División Zoología Vertebrados, Museo de La Plata, UNLPFil: Protogino, Lucila Cristina. División Zoología Vertebrados, Museo de La Plata, UNL

Mechanical Isolation of Highly Stable Antimonene under Ambient Conditions

Using mechanical exfoliation combined with a controlled double step transfer procedure we demonstrate that single layers of antimony can be readily produced. These flakes are not significantly contaminated upon exposure to ambient conditions and they do not react with water. DFT calculations confirm our experimental observations and predict a band gap of 1.2-1.3 eV (ambient conditions) for single layer antimonene, which is smaller than that calculated under vacuum conditions at 0 K. Our work confirms antimonene as a highly stable 2D material with promising relevant applications in optoelectronics.Comment: main paper: 5 pages, 4 figures supporting: 9 pages, 7 figures, Advanced Materials, 201

Comparison between two-fluid model simulations and particle image analysis & velocimetry (PIV) results for a two-dimensional gas-solid fluidized bed

This work compares simulation and experimental results of the hydrodynamics of a two-dimensional, bubbling air-fluidized bed. The simulation in this study has been conducted using an Eulerian–Eulerian two-fluid approach based on two different and well-known closure models for the gas–particle interaction: the drag models due to Gidaspow and Syamlal & O'Brien. The experimental results have been obtained by means of Digital Image Analysis (DIA) and Particle Image Velocimetry (PIV) techniques applied on a real bubbling fluidized bed of 0.005 m thickness to ensure its two-dimensional behaviour. Several results have been obtained in this work from both simulation and experiments and mutually compared. Previous studies in literature devoted to the comparison between two-fluid models and experiments are usually focused on bubble behaviour (i.e. bubble velocity and diameter) and dense-phase distribution. However, the present work examines and compares not only the bubble hydrodynamics and dense-phase probability within the bed, but also the time-averaged vertical and horizontal component of the dense-phase velocity, the air throughflow and the instantaneous interaction between bubbles and dense-phase. Besides, quantitative comparison of the time-averaged dense-phase probability as well as the velocity profiles at various distances from the distributor has been undertaken in this study by means of the definition of a discrepancy factor, which accounts for the quadratic difference between simulation and experiments The resulting comparison shows and acceptable resemblance between simulation and experiments for dense-phase probability, and good agreement for bubble diameter and velocity in two-dimensional beds, which is in harmony with other previous studies. However, regarding the time-averaged velocity of the dense-phase, the present study clearly reveals that simulation and experiments only agree qualitatively in the two-dimensional bed tested, the vertical component of the simulated dense-phase velocity being nearly an order of magnitude larger than the one obtained from the PIV experiments. This discrepancy increases with the height above the distributor of the two-dimensional bed, and it is even larger for the horizontal component of the time-averaged dense-phase velocity. In other words, the results presented in this work indicate that the fine agreement commonly encountered between simulated and real beds on bubble hydrodynamics is not a sufficient condition to ensure that the dense-phase velocity obtained with two-fluid models is similar to that from experimental measurements on two-dimensional bedsThis work has been partially funded by the Spanish Government (ProjectDPI2009-10518) and the Autonomous Community of Madrid (ProjectS2009/ENE-1660). Their supports are greatly appreciatedPublicad