Flow networks: A characterization of geophysical fluid transport

We represent transport between different regions of a fluid domain by flow networks, constructed from the discrete representation of the Perron-Frobenius or transfer operator associated to the fluid advection dynamics. The procedure is useful to analyze fluid dynamics in geophysical contexts, as illustrated by the construction of a flow network associated to the surface circulation in the Mediterranean sea. We use network-theory tools to analyze the flow network and gain insights into transport processes. In particular we quantitatively relate dispersion and mixing characteristics, classically quantified by Lyapunov exponents, to the degree of the network nodes. A family of network entropies is defined from the network adjacency matrix, and related to the statistics of stretching in the fluid, in particular to the Lyapunov exponent field. Finally we use a network community detection algorithm, Infomap, to partition the Mediterranean network into coherent regions, i.e. areas internally well mixed, but with little fluid interchange between them.Comment: 16 pages, 15 figures. v2: published versio

Conflicting sociabilities and residential alienation. The Rental housing discomforts in settlements popular consolidated from Lima Sur

El texto aborda el submercado de alquileres en asentamientos populares consolidados de Lima sur, a partir de los malestares de sus inquilinos; para ello se emplean los conceptos sociológicos de sociabilidad y subjetividad. Mediante el primer concepto, se describe cómo este sistema habitacional está generando relaciones altamente conflictivas. Mediante el segundo concepto se aborda cómo la experiencia del inquilinato se vive como alienación residencial. Se concluye mostrando cómo la experiencia residencial de los inquilinos nos presenta la peor cara de la densificación habitacional y se proponen algunas recomendaciones de política pública.In this article we discuss the submarket of rental housing, based on the discomforts of this tenure regime in consolidated popular settlements in southern Lima; from the concepts of sociability and subjectivity. Through the first concept, we describe how this housing system is generating highly conflictive relationships. The second concept addresses how that tenancy experience is lived as residential alienation. We finish showing how the residential experience of the tenants presents us the worst side of densification. At last, we propose some recommendations for public policy

Extracting Hα\alpha flux from photometric data in the J-PLUS survey

We present the main steps that will be taken to extract H$\alpha$ emission flux from Javalambre Photometric Local Universe Survey (J-PLUS) photometric data. For galaxies with $z\lesssim0.015$, the H$\alpha$+[NII] emission is covered by the J-PLUS narrow-band filter $F660$. We explore three different methods to extract the H$\alpha$ + [NII] flux from J-PLUS photometric data: a combination of a broad-band and a narrow-band filter ($r'$ and $F660$), two broad-band and a narrow-band one ($r'$, $i'$ and $F660$), and a SED-fitting based method using 8 photometric points. To test these methodologies, we simulated J-PLUS data from a sample of 7511 SDSS spectra with measured H$\alpha$ flux. Based on the same sample, we derive two empirical relations to correct the derived H$\alpha$+[NII] flux from dust extinction and [NII] contamination. We find that the only unbiased method is the SED fitting based one. The combination of two filters underestimates the measurements of the H$\alpha$ + [NII] flux by a 28%, while the three filters method by a 9%. We study the error budget of the SED-fitting based method and find that, in addition to the photometric error, our measurements have a systematic uncertainty of a 4.3%. Several sources contribute to this uncertainty: differences between our measurement procedure and the one used to derive the spectroscopic values, the use of simple stellar populations as templates, and the intrinsic errors of the spectra, which were not taken into account. Apart from that, the empirical corrections for dust extinction and [NII] contamination add an extra uncertainty of 14%. Given the J-PLUS photometric system, the best methodology to extract H$\alpha$ + [NII] flux is the SED-fitting based one. Using this method, we are able to recover reliable H$\alpha$ fluxes for thousands of nearby galaxies in a robust and homogeneous way.Comment: 11 pages, 14 figures. Minor changes to match the published versio

Optimizing the search for resources by sharing information: Mongolian gazelles as a case study

We investigate the relationship between communication and search efficiency in a biological context by proposing a model of Brownian searchers with long-range pairwise interactions. After a general study of the properties of the model, we show an application to the particular case of acoustic communication among Mongolian gazelles, for which data are available, searching for good habitat areas. Using Monte Carlo simulations and density equations, our results point out that the search is optimal (i.e., the mean first hitting time among searchers is minimum) at intermediate scales of communication, showing that both an excess and a lack of information may worsen it. © 2013 American Physical Society.R. M.-G. is supported by the JAEPredoc program of CSIC. R. M.-G. and C. L. acknowledge support from MICINN (Spain) and FEDER (EU) through Grant No. FIS2007-60327 FISICOS. J. M. C. and T. M. were supported by a U.S. National Science Foundation grant (ABI 1062411).Peer Reviewe

Temperature dependence of the E2h phonon mode of wurtzite GaN/AlN quantum dots

Raman scattering has been used to study the temperature dependence of the frequency and linewidth of the E2h phonon mode of GaN/AlN quantum dot stacks grown on 6H-SiC. The evolution of the nonpolar phonon mode was analyzed in the temperature range from 80 to 655 K for both quantum dots and barrier materials. The experimental results are interpreted by comparison with a model that takes into account symmetric phonon decay and the different thermal expansions of the constituents of the heterostructure. We find a small increase in the anharmonic parameters of the phonon modes in the heterostructure with respect to [email protected] [email protected] [email protected]

Twitter, partisan use and institutional use: Comparative analysis between the profiles of Moncloa, Madrid City Council and their ruling parties

This paper seeks to compare and analyse the differences in the use of Twitter that, Partido Popular, as a traditional political party, and Ahora Madrid, as a new political party, make of the institutional channels for the public institutions that they administer. In addition, the present study analyses three different periods in the electoral process: the pre-campaign, campaign and post-campaign during the Spanish general elections of December 20th, 2015 in order to see if the election periods caused changes in their communications on Twitter. The sample consists of four cases divided into two groups for content analysis. On one hand, the Government’s Twitter profile (@desdelamoncloa) and of its ruling party, Partido Popular (@ppopular), comprise the old political group, while the Madrid City Council (@Madrid) and its ruling party, Ahora Madrid (@AhoraMadrid), are integrated into the new political group. Additionally, word clouds provide a visual representation of the main terms used by each group. The study results show which group uses and better leverages Twitter’s potential, in that Partido Popular and Moncloa have clearer differences between party and institutional channels, while Ahora Madrid and the Madrid City Council do not seem to be as clear about the difference between the two concepts and use the party channel as the city council channel. However, the results demonstrate that the new political profile leverages Twitter’s potential more.El presente trabajo analiza las diferencias de uso de Twitter por parte de dos partidos políticos españoles, Partido Popular, como partido tradicional, y Ahora Madrid, como nuevo partido, así como la utilización de los canales institucionales de los entes públicos que estos partidos presiden a nivel nacional y local, respectivamente. Los resultados muestran usos y aprovechamientos diferentes de las potencialidades de Twitter. El estudio se realizó en tres periodos electorales diferenciados: precampaña, campaña y post-campaña de las elecciones generales del 20 de diciembre de 2015, para examinar también cambios de comportamiento en la comunicación en Twitter en el periodo electoral. La muestra consta de cuatro casos divididos en dos grupos para el análisis de contenido. Por un lado, el perfil en Twitter del Gobierno (@desdelamoncloa) y el del partido gobernante, el Partido Popular (@ppopular) constituyen el grupo de la vieja política. Por otro lado, el Ayuntamiento de Madrid (@madrid) y su partido gobernante, Ahora Madrid (@AhoraMadrid), se integran dentro del grupo de nueva política. Además, unas nubes de palabras presentarán visualmente las principales ideas enviadas por los perfiles. Los resultados indican que Partido Popular y Moncloa mantuvieron un uso diferenciado entre los canales de partido y los institucionales, mientras que en el caso de Ahora Madrid y el Ayuntamiento de Madrid se constataron usos concluyentes y no diferenciados entre el canal del partido y el institucional. Además, se observa que los perfiles de la nueva política aprovechan más las potencialidades de Twitter

Biological protein precipitation: a green process for the extraction of cucumisin from melon (Cucumis melo L. inodorus) by-products

Cucumisin (CUC) from industrial melon by-products was separated for the first time through biological precipitation using carrageenan (CRG). This approach could represent a cost-effective and environmentally friendly process for the industries, avoiding the use of expensive equipment and toxic salts or solvents, such as butanol and ethanol. In this study, biological precipitation of proteins from melon by-products using CRG was studied and compared with conventional precipitation with ammonium sulphate. Different methods were applied for the identification and characterization of isolated proteins, including SDS-PAGE gel, FPLC and proteolytic activity assays. The isolated CUC confirmed a molecular weight of 68 kDa and showed highly stable proteolytic (PA) and milk-clotting (MCA) activities in a wide range of CaCl2 (20 to 60 mM), pH (5 to 7) and temperatures (30 to 85 ºC). Melon peel extract demonstrated to possess significant PA (4.24 U/mg protein) and MCA (191.50 MCU/mg protein), but such values were increased by ammonium sulphate precipitation (1.60 and 2.06-folds, respectively), and specially a noticeable increment was observed by biological precipitation with 2.11 and 17.65-folds, respectively, demonstrating the capability to be an effective strategy to isolate and purify CUC, allowing a yield of 0.17 g CUC/100 g of by-products and keeping its biological properties.info:eu-repo/semantics/publishedVersio

Temporal Griffiths Phases

Disorder is an unavoidable ingredient of real systems. Spatial disorder generates Griffiths phases (GPs) which, in analogy to critical points, are characterized by a slow relaxation of the order parameter and divergences of quantities such as the susceptibility. However, these singularities appear in an extended region of the parameter space and not just at a (critical) point, i.e. there is generic scale invariance. Here, we study the effects of temporal disorder, focusing on systems with absorbing states. We show that for dimensions $d \geq 2$ there are Temporal Griffiths phases (TGPs) characterized by generic power-law spatial scaling and generic divergences of the susceptibility. TGPs turn out to be a counterpart of GPs, but with space and time playing reversed roles. TGPs constitute a unifying concept, shedding light on the non-trivial effects of temporal disorder.Comment: 4 pages, 3 figures; Accepted in PR

Crystallization and melting of bacteria colonies and Brownian Bugs

Motivated by the existence of remarkably ordered cluster arrays of bacteria colonies growing in Petri dishes and related problems, we study the spontaneous emergence of clustering and patterns in a simple nonequilibrium system: the individual-based interacting Brownian bug model. We map this discrete model into a continuous Langevin equation which is the starting point for our extensive numerical analyses. For the two-dimensional case we report on the spontaneous generation of localized clusters of activity as well as a melting/freezing transition from a disordered or isotropic phase to an ordered one characterized by hexagonal patterns. We study in detail the analogies and differences with the well-established Kosterlitz-Thouless-Halperin-Nelson-Young theory of equilibrium melting, as well as with another competing theory. For that, we study translational and orientational correlations and perform a careful defect analysis. We find a non standard one-stage, defect-mediated, transition whose nature is only partially elucidated.Comment: 13 Figures. 14 pages. Submitted to Phys. Rev.

The GALANTE Photometric System

This paper describes the characterization of the GALANTE photometric system, a seven intermediate- and narrow-band filter system with a wavelength coverage from 3000 $\r{A}$ to 9000 $\r{A}$ . We describe the photometric system presenting the full sensitivity curve as a product of the filter sensitivity, CCD, telescope mirror, and atmospheric transmission curves, as well as some first- and second-order moments of this sensitivity function. The GALANTE photometric system is composed of four filters from the J-PLUS photometric system, a twelve broad-to-narrow filter system, and three exclusive filters, specifically designed to measure the physical parameters of stars such as effective temperature $T_{\rm eff}$, $\log(g)$, metallicity, colour excess $E(4405-5495)$, and extinction type $R_{5495}$. Two libraries, the Next Generation Spectral Library (NGSL) and the one presented in Ma\'iz Apell\'aniz & Weiler (2018), have been used to determine the transformation equations between the Sloan Digital Sky Survey ($\textit{SDSS}$) $\textit{ugriz}$ photometry and the GALANTE photometric system. We will use this transformation to calibrate the zero points of GALANTE images. To this end, a preliminary photometric calibration of GALANTE has been made based on two different $\textit{griz}$ libraries ($\textit{SDSS}$ DR12 and ATLAS All-Sky Stellar Reference Catalog, hereinafter $\textit{RefCat2}$). A comparison between both zero points is performed leading us to the choice of $\textit{RefCat2}$ as the base catalogue for this calibration, and applied to a field in the Cyg OB2 association.Comment: Accepted in MNRA