Evidence of chaotic modes in the analysis of four delta Scuti stars

Since CoRoT observations unveiled the very low amplitude modes that form a flat plateau in the power spectrum structure of delta Scuti stars, the nature of this phenomenon, including the possibility of spurious signals due to the light curve analysis, has been a matter of long-standing scientific debate. We contribute to this debate by finding the structural parameters of a sample of four delta Scuti stars, CID 546, CID 3619, CID 8669, and KIC 5892969, and looking for a possible relation between these stars' structural parameters and their power spectrum structure. For the purposes of characterization, we developed a method of studying and analysing the power spectrum with high precision and have applied it to both CoRoT and Kepler light curves. We obtain the best estimates to date of these stars' structural parameters. Moreover, we observe that the power spectrum structure depends on the inclination, oblateness, and convective efficiency of each star. Our results suggest that the power spectrum structure is real and is possibly formed by 2-period island modes and chaotic modes

Source identification for mobile devices, based on wavelet transforms combined with sensor imperfections

One of the most relevant applications of digital image forensics is to accurately identify the device used for taking a given set of images, a problem called source identification. This paper studies recent developments in the field and proposes the mixture of two techniques (Sensor Imperfections and Wavelet Transforms) to get better source identification of images generated with mobile devices. Our results show that Sensor Imperfections and Wavelet Transforms can jointly serve as good forensic features to help trace the source camera of images produced by mobile phones. Furthermore, the model proposed here can also determine with high precision both the brand and model of the device

Image Science And Model Didcatico

RESUMEN El objetivo de la investigación es determinar las concepciones respecto a la ciencia de un grupo de cinco docentes de educación básica en una institución oficial, y su influencia con el modelo didáctico que implementan en la enseñanza y el aprendizaje de las ciencias naturales. Para identificar y analizar las concepciones y su relación con el modelo didáctico, se sigue un método de investigación cualitativa descriptiva, se definen como categorías de análisis: imagen de ciencia, metodología de la enseñanza, teoría del aprendizaje y modelo didáctico; se emplean técnicas en la recolección de la información como: la observación de las prácticas, la entrevista semiestructurada y la encuesta utilizando el cuestionario o Inventario de Creencias Pedagógicas y Científicas de los Profesores INPECIP diseñado y validado por Porlán et al. (1997). Los resultados obtenidos muestran una correspondencia entre concepciones epistemológicas y su relación con el modelo didáctico en la enseñanza de las ciencias. ABSTRACT The objective of this research is to determine the conceptions about the science of a group of five primary school teachers in a public institution, andhis influence with the didactic model implemented in the teaching and learning of science. To identify and analyze the concepts and their relationship to the teaching model, it follows a descriptive qualitative research method, are defined as categories of analysis: images of science, teaching methods, learning theory and teaching model, techniques are used in collection of information such as: observation of practices, the semistructured interview and the survey using the questionnaire or Belief Inventory Educational and Scientific INPECIP Teachers designed and validated by Porlán et al. (1997). The results show a correspondence between epistemological and its relation to the didactic model for teaching science

Edge detection algorithm based on fuzzy logic theory for a local vision system of robocup humanoid league

Este artículo presenta el desarrollo de un algoritmo para la extracción de bordes basado en la teoría de lógica difusa, mediante el cual es posible reconocer las marcas de un campo de juego para la liga humanoide de RoboCup. El algoritmo propuesto describe la creación de un sistema de inferencia difuso que permite evaluar la relación existente entre los pixeles de una imagen, encontrando así las variaciones en los niveles de gris para una vecindad de pixeles específica. Posteriormente se plantea la implementación del método OTSU para binarizar la imagen obtenida en el proceso difuso y así generar una imagen que contiene solo los bordes extraídos, validando el algoritmo en imágenes de la liga humanoide. Luego se analizan los resultados obtenidos evidenciando el buen desempeño del algoritmo, considerando que el tiempo de procesamiento de la propuesta es tan solo el 35% más del tiempo necesario en métodos tradicionales, mientras que los bordes extraídos son unos 52% menos susceptibles al ruido.At this paper we shown the development of an algorithm to perform edges extraction based on fuzzy logic theory. This method allows recognizing landmarks on the game field for Humanoid League of RoboCup. The proposed algorithm describes the creation of a fuzzy inference system that permit evaluate the existent relationship between image pixels, finding variations on grey levels of related neighbor pixels. Subsequently, it shows an implementation of OTSU method to binarize an image that was obtained from fuzzy process and so generate an imagecontaining only extracted edges, validating the algorithm with Humanoid League images. Later, we analyze obtained results that evidence a good performance of algorithm, considering that this proposal only takes an extra 35% processing time that will be required by traditional methods, whereas extracted edges are 52% less noise susceptible

Polarisation Patterns and Vectorial Defects in Type II Optical Parametric Oscillators

Previous studies of lasers and nonlinear resonators have revealed that the polarisation degree of freedom allows for the formation of polarisation patterns and novel localized structures, such as vectorial defects. Type II optical parametric oscillators are characterised by the fact that the down-converted beams are emitted in orthogonal polarisations. In this paper we show the results of the study of pattern and defect formation and dynamics in a Type II degenerate optical parametric oscillator for which the pump field is not resonated in the cavity. We find that traveling waves are the predominant solutions and that the defects are vectorial dislocations which appear at the boundaries of the regions where traveling waves of different phase or wave-vector orientation are formed. A dislocation is defined by two topological charges, one associated with the phase and another with the wave-vector orientation. We also show how to stabilize a single defect in a realistic experimental situation. The effects of phase mismatch of nonlinear interaction are finally considered.Comment: 38 pages, including 15 figures, LATeX. Related material, including movies, can be obtained from http://www.imedea.uib.es/Nonlinear/research_topics/OPO

Desarrollo para la comercialización y ventas nacionales e internacionales I CEDECOM "CTI TECHNICAL SERVICES"

El desarrollo de este proyecto surgió de la necesidad que se presenta en la empresa de generalizar el conocimiento que se debe de tener acerca de las implicaciones existentes en los procesos de importación que se deben llevar a cabo en México con el fin de agilizar los procesos logísticos de la empresa. Uno de los principales objetivos de este proyecto estuvo enfocado en encontrar la manera de plasmar el proceso de importación de mercancías y explicarlo de una forma lo más entendible y sencillo posible, esto con el fin de que cualquier persona (que tenga o no conocimientos previos acerca de este tema) pueda comprenderlo a su totalidad y le sea útil para tener una idea más amplia acerca de los trámites y procesos necesarios para lograr un correcto despacho aduanero en México. La manera en la que se logró explicar con mayor detalle este proceso, fue realizando un diagrama de flujo en el que se explican todos los procedimientos que se deben llevar a cabo con el fin de completar una importación al territorio mexicano; este diagrama fue hecho específicamente para la empresa, por lo que está adaptado a la forma en la que esta usualmente realiza sus importaciones, especificando paso a paso los procedimientos a realizarse, el encargado de cada procedimiento y los tiempos aproximados que se deben destinar para completar cada uno de los pasos a seguir. De igual manera, con el fin de lograr una adaptación lo más enfocada posible a este proyecto, se trabajó previamente en un análisis de información de distintos aspectos de la empresa, como lo son: situación actual de la empresa, principales productos importados sus especificaciones, rutas logísticas que se utilizan y la manera en la que actualmente llevan a cabo sus procesos aduanales en México.ITESO, A.C

Looking the void in the eyes - the kSZ effect in LTB models

As an alternative explanation of the dimming of distant supernovae it has recently been advocated that we live in a special place in the Universe near the centre of a large void described by a Lemaitre-Tolman-Bondi (LTB) metric. The Universe is no longer homogeneous and isotropic and the apparent late time acceleration is actually a consequence of spatial gradients in the metric. If we did not live close to the centre of the void, we would have observed a Cosmic Microwave Background (CMB) dipole much larger than that allowed by observations. Hence, until now it has been argued, for the model to be consistent with observations, that by coincidence we happen to live very close to the centre of the void or we are moving towards it. However, even if we are at the centre of the void, we can observe distant galaxy clusters, which are off-centre. In their frame of reference there should be a large CMB dipole, which manifests itself observationally for us as a kinematic Sunyaev-Zeldovich (kSZ) effect. kSZ observations give far stronger constraints on the LTB model compared to other observational probes such as Type Ia Supernovae, the CMB, and baryon acoustic oscillations. We show that current observations of only 9 clusters with large error bars already rule out LTB models with void sizes greater than approximately 1.5 Gpc and a significant underdensity, and that near future kSZ surveys like the Atacama Cosmology Telescope, South Pole Telescope, APEX telescope, or the Planck satellite will be able to strongly rule out or confirm LTB models with giga parsec sized voids. On the other hand, if the LTB model is confirmed by observations, a kSZ survey gives a unique possibility of directly reconstructing the expansion rate and underdensity profile of the void.Comment: 20 pages, 9 figures, submitted to JCA

High-pressure theoretical and experimental study of HgWO4

This is an Author's Accepted Manuscript of an article published in Lopez-Solano, J.; Rodriguez-Hernandez, P.; Muñoz, A.; Santamaria-Perez, D. et al.(2011). High-pressure theoretical and experimental study of HgWO4. High Pressure Research. 31(1):58-63. doi:10.1080/08957959.2010.521735HgWO 4 at ambient pressure is characterized using a combination of ab initio calculations, X-ray diffraction and Raman scattering measurements. The effect of low pressure and temperature on the structural stability is analysed. Extending our ab initio study to the range of higher pressures, a sequence of stable phases up to 30GPa is proposed. © 2011 Taylor & Francis.We thank J.M. Menendez for his help in the use of the GIBBS code. This work has been supported by the Spanish MEC under Projects MAT2007-65990-C03-01/03, MAT2010-21270-C04-03/04 and CSD-2007-00045 and by the "Vicerrectorado de Innovacion y Desarrollo de la UPV" (PAID-05-2009 through project UPV2010-0096). We gratefully acknowledge computational time provided by the "Red Espanola de Supercomputacion" at the supercomputer "Atlante". S. R. acknowledges financial support from the "Vicerrectorado de Investigacion de la UPV" through grant PAID-02-09-3085.Lopez-Solano, J.; Rodriguez-Hernandez, P.; Muñoz, A.; Santamaria-Perez, D.; Manjón Herrera, FJ.; Ray, S.; Gomis Hilario, O.... (2011). High-pressure theoretical and experimental study of HgWO4. High Pressure Research. 31(1):58-63. https://doi.org/10.1080/08957959.2010.521735S5863311Manjón, F. J., & Errandonea, D. (2009). Pressure-induced structural phase transitions in materials and earth sciences. physica status solidi (b), 246(1), 9-31. doi:10.1002/pssb.200844238Errandonea, D., Manjón, F. J., Garro, N., Rodríguez-Hernández, P., Radescu, S., Mujica, A., … Tu, C. Y. (2008). Combined Raman scattering andab initioinvestigation of pressure-induced structural phase transitions in the scintillatorZnWO4. Physical Review B, 78(5). doi:10.1103/physrevb.78.054116Ruiz-Fuertes, J., López-Moreno, S., Errandonea, D., Pellicer-Porres, J., Lacomba-Perales, R., Segura, A., … González, J. (2010). High-pressure phase transitions and compressibility of wolframite-type tungstates. Journal of Applied Physics, 107(8), 083506. doi:10.1063/1.3380848Lacomba-Perales, R., Errandonea, D., Martinez-Garcia, D., Rodríguez-Hernández, P., Radescu, S., Mujica, A., … Polian, A. (2009). Phase transitions in wolframite-typeCdWO4at high pressure studied by Raman spectroscopy and density-functional theory. Physical Review B, 79(9). doi:10.1103/physrevb.79.094105Manjón, F. J., López-Solano, J., Ray, S., Gomis, O., Santamaría-Pérez, D., Mollar, M., … Muñoz, A. (2010). High-pressure structural and lattice dynamical study ofHgWO4. Physical Review B, 82(3). doi:10.1103/physrevb.82.035212Kresse, G., & Hafner, J. (1993). Ab initiomolecular dynamics for liquid metals. Physical Review B, 47(1), 558-561. doi:10.1103/physrevb.47.558Kresse, G., & Furthmüller, J. (1996). Efficient iterative schemes forab initiototal-energy calculations using a plane-wave basis set. Physical Review B, 54(16), 11169-11186. doi:10.1103/physrevb.54.11169Blöchl, P. E. (1994). Projector augmented-wave method. Physical Review B, 50(24), 17953-17979. doi:10.1103/physrevb.50.17953Perdew, J. P., Ruzsinszky, A., Csonka, G. I., Vydrov, O. A., Scuseria, G. E., Constantin, L. A., … Burke, K. (2008). Restoring the Density-Gradient Expansion for Exchange in Solids and Surfaces. Physical Review Letters, 100(13). doi:10.1103/physrevlett.100.136406Monkhorst, H. J., & Pack, J. D. (1976). Special points for Brillouin-zone integrations. Physical Review B, 13(12), 5188-5192. doi:10.1103/physrevb.13.5188Blanco, M. A., Francisco, E., & Luaña, V. (2004). GIBBS: isothermal-isobaric thermodynamics of solids from energy curves using a quasi-harmonic Debye model. Computer Physics Communications, 158(1), 57-72. doi:10.1016/j.comphy.2003.12.001Kresse, G., Furthmüller, J., & Hafner, J. (1995). Ab initioForce Constant Approach to Phonon Dispersion Relations of Diamond and Graphite. Europhysics Letters (EPL), 32(9), 729-734. doi:10.1209/0295-5075/32/9/005Wahl, R., Vogtenhuber, D., & Kresse, G. (2008). SrTiO3andBaTiO3revisited using the projector augmented wave method: Performance of hybrid and semilocal functionals. Physical Review B, 78(10). doi:10.1103/physrevb.78.104116Jeitschko, W., & Sleight, A. W. (1973). The crystal structure of HgMoO4 and related compounds. Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 29(4), 869-875. doi:10.1107/s056774087300347

A Performance Analysis Framework for WiFi/WiMAX Heterogeneous Metropolitan Networks Based on Cross-Layer Design

The communication between network nodes within different protocol domains is often regarded simply as a black box with unknown configuration conditions in the path. We address network heterogeneity using a white box approach and focus on its interconnection processes. To achieve this purpose, a Performance Analysis Framework (PAF) is proposed which is composed of the formalization of the latter using process algebra (PA) and the corresponding teletraffic performance models. In this contribution, we target the IEEE 802.16 and IEEE 802.11 protocols. For the teletraffic models, we extend previous models for such scenario with the inclusion of the following protocol operational parameters (metrics): bit error rate (BER), packet error ratio (PER), and packet length (pl). From the framework teletraffic models, the optimal packet length (OPL), end to end throughput, delay, and packet loss are obtained. The PAF outperforms previous modeling solutions in terms of delay and throughput relative to NS3 simulation results. </jats:p

Daily monitoring of TeV gamma-ray emission from Mrk 421, Mrk 501, and the Crab Nebula with HAWC

We present results from daily monitoring of gamma rays in the energy range $\sim0.5$ to $\sim100$ TeV with the first 17 months of data from the High Altitude Water Cherenkov (HAWC) Observatory. Its wide field of view of 2 steradians and duty cycle of $>95$% are unique features compared to other TeV observatories that allow us to observe every source that transits over HAWC for up to $\sim6$ hours each sidereal day. This regular sampling yields unprecedented light curves from unbiased measurements that are independent of seasons or weather conditions. For the Crab Nebula as a reference source we find no variability in the TeV band. Our main focus is the study of the TeV blazars Markarian (Mrk) 421 and Mrk 501. A spectral fit for Mrk 421 yields a power law index $\Gamma=2.21 \pm0.14_{\mathrm{stat}}\pm0.20_{\mathrm{sys}}$ and an exponential cut-off $E_0=5.4 \pm 1.1_{\mathrm{stat}}\pm 1.0_{\mathrm{sys}}$ TeV. For Mrk 501, we find an index $\Gamma=1.60\pm 0.30_{\mathrm{stat}} \pm 0.20_{\mathrm{sys}}$ and exponential cut-off $E_0=5.7\pm 1.6_{\mathrm{stat}} \pm 1.0_{\mathrm{sys}}$ TeV. The light curves for both sources show clear variability and a Bayesian analysis is applied to identify changes between flux states. The highest per-transit fluxes observed from Mrk 421 exceed the Crab Nebula flux by a factor of approximately five. For Mrk 501, several transits show fluxes in excess of three times the Crab Nebula flux. In a comparison to lower energy gamma-ray and X-ray monitoring data with comparable sampling we cannot identify clear counterparts for the most significant flaring features observed by HAWC.Comment: 18 pages, 10 figures, accepted for publication in The Astrophysical Journa