Star formation in Seyfert galaxies

An analysis of the IRAS data for a sample of classical (optically selected) Seyfert galaxies is presented. The IRAS fluxes at 25 micron, 60 micron, and 100 micron are found to be uncorrelated or only very weakly correlated with the UV/Optical continuum flux and the near and mid IR flux at 3.5 and 10 microns. To investigate the possibility that star formation accounts for the far IR flux, the IRAS measurements for the Seyfert galaxies are compared to IRAS observations of a sample of normal spiral galaxies, and a sample of Starburst galaxies. It is shown that the far IR luminosities and far IR colors of Seyfert galaxies are indistinguishable from those of the Starburst galaxies. Besides, normal galaxies are an order of magnitude less luminous than both the Seyfert and the Starburst galaxies. This indicates that star formation produces the bulk of the far infrared emission in Seyfert galaxies

Condensation in an Economic Model with Brand Competition

We present a linear agent based model on brand competition. Each agent belongs to one of the two brands and interacts with its nearest neighbors. In the process the agent can decide to change to the other brand if the move is beneficial. The numerical simulations show that the systems always condenses into a state when all agents belong to a single brand. We study the condensation times for different parameters of the model and the influence of different mechanisms to avoid condensation, like anti monopoly rules and brand fidelity.Comment: Accepted in: International Journal of Modern Physics

Moving embedded lattice solitons

It was recently proved that isolated unstable "embedded lattice solitons" (ELS) may exist in discrete systems. The discovery of these ELS gives rise to relevant questions such as the following: are there continuous families of ELS?, can ELS be stable?, is it possible for ELS to move along the lattice?, how do ELS interact?. The present work addresses these questions by showing that a novel differential-difference equation (a discrete version of a complex mKdV equation) has a two-parameter continuous family of exact ELS. The numerical tests reveal that these solitons are stable and robust enough to withstand collisions. The model may apply to the description of a Bose-Einstein condensate with dipole-dipole interactions between the atoms, trapped in a deep optical-lattice potential.Comment: 13 pages, 11 figure

Los sistemas de barrancos del sur del Estado de México: Análisis geográfico

En el anexo se encuentra una tabla de especies vegetales en el sur del Estado de México correspondientes al año 2014En el siglo pasado, los sistemas de barrancos eran considerados como lugares sin ninguna función e importancia, por lo que, algunos de éstos han sido impactados por la influencia directa e indirecta de las actividades humanas. En la actualidad, los estudios multidisciplinarios de estos ambientes han tomado relevancia como una estrategia de conservación y protección. Ciencias como la Geografía, Ecología, Geología, Sociología y la Antropología Social, han enfocado algunas de sus investigaciones a estos espacios, sobre todo por sus paisajes, biodiversidad, recursos naturales y majestuosidad de sus profundidades. Mediante trabajo de campo, técnicas de teledetección y aplicación de herramientas de sistemas de información geográfica fueron identificados y representados de forma cartográfica los sistemas de barrancos que forman una parte de la Provincia Fisiográfica de la Sierra Madre del Sur, en la porción correspondiente al territorio del Estado de México, esto con el propósito de analizar los procesos ambientales y sociales que interactúan en los sistemas, así como establecer propuestas de conservación y aprovechamiento sustentable. La investigación se sustentó en los principios de la geografía, la geografía ambiental, la geografía del paisaje, la teoría general de sistema y fundamentos teóricos asociados con el concepto de barrancos. Los resultados obtenidos demuestran que en los sistemas de barrancos hay varios ambientes (ecosistemas) que socio-culturalmente representan una reserva de recursos naturales, utilizados por la sociedad con fines agrícolas, alimentarios, medicinales, ornamentales, ceremoniales, forrajeros, para construcción y como combustible. Además desempeñan funciones ecológicas, ambientales, climáticas y paisajísticas

Synthesis and characterization of silver vanadates thin films for photocatalytic applications

Silver vanadates thin films were deposited by a hybrid deposition system combining laser ablation and thermal evaporation. A high purity vanadium target was ablated using the third harmonic of a Nd:YAG laser whereas high purity silver pellets were evaporated. The as-deposited thin films were subjected to thermal treatments at 400 °C to obtain crystalline films. For films without Ag amorphous V2O5 thin films were deposited and as the Ag is incorporated in the material different silver vanadates were obtained. The effect of the silver load on the composition, structure, optical properties, surface morphology and photocatalytic response of the deposited films was studied. The film composition, determined by X-ray photoelectron spectroscopy, reveals Ag contents from 5.5 to 18.9 at.%. The crystalline phases formed were identified by micro-Raman Spectroscopy; the results indicate the formation of three silver vanadates depending on the silver content. The morphology was observed using scanning electron microscopy, the filmś surface changes from a smooth surface to belts covering the surface and finally Ag nanoparticles are observed at the higher Ag contens. Optical properties determined from UV–vis reveal the presence of the surface plasmon signal in films containing silver. The films were tested in the photocatalytic degradation of Malachite Green dye reaching maximum degradations degrees close to 53% under solar irradiation. Reactive species trapping experiments suggest that O2 − produced by the O2 reduction via the photogenerated electrons drives the photodegradation mechanismCB-168827 CB-240998 F. Gonzalez-Zavala thanks to CONACyT for the PhD and Beca Mixta grants, and also to the SIEA-UAEM for the beca movilidad para estudios avanzados 2016. E. Rodríguez-Castellón thanks to project CTQ2015-68951-C3-3-R of Ministerio de Economía y Competitividad (Spain) and FEDER funds