Effect of extinction on the high-energy optical response of photonic crystals

An analysis of the optical response of photonic crystals in the high-order band energy range is herein presented. High and abruptly fluctuating specular reflectance is predicted for perfect lattices at those energies even in the absence of any photonic gap or pseudogap. As optical extinction is gradually introduced, it is possible to reproduce experimental results found in the literature and which have recently been the subject of an intense debate. Band structure calculations demonstrate that extinction is extraordinarily amplified in the high-energy range and is responsible for the features so far observed in that range in real crystalsConsejo Superior de Investigaciones Científicas 2005AR0070Universidad de Buenos Aires ANPCYT-BID 802Agencia Nacional de Promoción Científica y Tecnológica OC-AR03-14099Ministerio de Educación y Ciencia MAT2005-0302

Towards a full understanding of the growth dynamics and optical response of self-assembled photonic colloidal crystal films

Recent advances in the comprehension of the growth dynamics of colloidal crystal films opens the door to rational design of experiments aiming at fabricating lattices in which the density of intrinsic defects is minimized. Since such imperfections have a dramatic effect on scattered light of wavelength smaller than the lattice constant, the evaluation of the experimental optical response at those energy ranges, based on the comparison to rigorous calculations, is identified as the most sensitive guide to accurately evaluate the progress towards the actual realization of defect-free colloidal crystals.Ministerio de Ciencia y Educación MAT200503028Consejo Superior de Investigaciones Científicas 2005AR007

Interplay between crystal-size and disorder effects in the high-energy optical response of photonic crystal slabs

Experimental reflectance spectra have been obtained for colloidal crystals whose widths ranged from one to several sphere monolayers, and their features in the higher order band energy range have been reproduced theoretically. In order to fit the measured data, optical extinction has been introduced in the theoretical model, which accounts for structure imperfections and disorder, the main sources of losses in an actual measurement. A complex spectrum in the high frequency region is observed even for one ordered monolayer, being this peak structure gradually modified as more layers are piled up. This allowed us to identify which peaks are reminiscent of the optical reflectance features of a single close-packed layer and which are the result of building up a three dimensional periodicity. A clear correlation between the amount of extinction introduced in the fitting and the slab width has been found, which demonstrates that wider real crystals produce less diffusely scattered light. At the same time, we find that the optical response of thinner crystals is more robust against the introduction of extinction than that of thicker ones, for which the effect is dramatic.Consejo Superior de Investigaciones Científicas 2005AR0070Universidad de Buenos Aires ANPCYT-BID 802Agencia Nacional de Promoción Científica y Tecnológica OC-AR03-14099Ministerio de Ciencia y Educación MAT2005-0302

Physical origin of the high energy optical response of three-dimensional photonic crystals

The physical origin of the optical response observed in three-dimensional photonic crystals when the photon wavelength is equal or lower than the lattice parameter still remains unsatisfactorily explained and is the subject of an intense and interesting debate. Herein we demonstrate for the first time that all optical spectra features in this high energy region of photonic crystals arise from electromagnetic resonances within the ordered array, modified by the interplay between these resonances with the opening of diffraction channels, the presence of imperfections and finite size effects. AU these four phenomena are taken into account in our theoretical approach to the problem, which allows us to provide a full description of the observed optical response based on fundamental phenomena as well as to attain fair fittings of experimental results.Consejo Superior de Investigaciones Científicas 2005AR0070Universidad de Buenos Aires ANPCYT-BID 802Agencia Nacional de Promoción Científica y Tecnológica OC-AR03-14099Ministerio de Ciencia y Educación MAT2005-0302

Software público, libre, abierto, gratuito, privativo y comercial para la innovación y mejora de la calidad en la docencia, investigación, gestión y asistencia

The public free software (now renamed as open software) is the basis of the open source software (OSS) project. This initiative promotes the use of open standards and platform-independent accessibility. Many OSS products are free or low cost, which allows their deployment even in the absence of large economic resources (developing countries, schools, etc.). Besides, their source code can be modified, adapted and optimized by anyone, since it is public. Nevertheless, the OSS may also have drawbacks. Thus, its development may not be as orderly and hierarchical as the privative software is, and may not have an appropriate funding. This may jeopardize the ease of use and coherence of the final product, increasing the transition, training and technical support costs. Besides, it must be taken into account that there is also commercial open software, as well as free privative software. In any case, the excellence of the software may be independent of such variables. Thus, the best strategy is the coexistence and free competition of all kinds of software. This will allow a quality improvement and an innovation enhancement, which will benefit the education, research, management and assistance at the university in particular and at the whole society in general.El software público libre es el fundamento del movimiento de software de fuente abierta (OSS). Éste puede facilitar el uso de estándares abiertos, con accesibilidad independiente de plataforma informática. El bajo coste o gratuidad de muchos productos OSS permite su implantación cuando los recursos económicos son escasos (países en desarrollo, escuelas, etc.). Además, su código se puede modificar, adaptar y mejorar por cualquiera, ya que es público. No obstante, el OSS también puede presentar inconvenientes. Así, su desarrollo puede no ser tan ordenado y jerárquico como el del software privativo y puede no tener una financiación apropiada. De este modo, puede verse comprometida la facilidad de uso y coherencia del producto final. Ello puede incrementar los costes de transición, entrenamiento y soporte técnico. Por otra parte, conviene recordar que existe software libre comercial y software privativo gratuito. En cualquier caso, la excelencia del software puede ser independiente de dichas variables. Por tanto, la mejor estrategia es la coexistencia y libre competencia de todo tipo de software. Así se puede conseguir una mejora de calidad y una potenciación de la innovación, que beneficie a la docencia, investigación, gestión y asistencia universitarias en particular, así como a la sociedad en general

Análisis de la capacidad explicativa de las pruebas de detección de talento en el rendimiento en competición de jóvenes triatletas

El objetivo es establecer la relación entre las pruebas de detecciónde talentos de la federación española de triatlón (FETRI) y los resultadosobtenidos en el campeonato de España del mismo año. La muestrafue formada por 489 triatletas federados (342 hombres, 147 mujeres, 271junior y 218 cadetes). Las variables independientes han sido las pruebasque conforman el proceso de detección de talentos de la FETRI: 100m denatación estilo libre, 1000m de natación estilo libre, 400m lisos, 1000mlisos, y se ha utilizado como variable dependiente el puesto obtenido en elCampeonato de España de triatlón. Se implementó un análisis de componentesde varianza (p<0,05), usando procedimientos de mínimos cuadrados(Varcomp) y de máxima verosimilitud (GLM) y un análisis de generalizabilidad.Los resultados indican que el modelo es significativo (p=0,0251)y que tres variables resultan significativas para explicar el puesto obtenidoen el campeonato de España de triatlón (natación de 100 y 1000 metros ycarrera de 1000 metros), sin embargo ninguna de sus interacciones resultasignificativa, así como tampoco la carrera de 400 metros. El modelo presentaun excelente nivel de fiabilidad (e2 = 1) y de generalizabilidad (Φ = 1).En conclusión, el resultado en el Campeonato de España no encuentra unaexplicación satisfactoria a través de las pruebas de detección de talentosmarcadas por la FETRI por lo que una posible solución sería mantenerlas pruebas que han mostrado una alta capacidad explicativa, y sustituir aaquellas otras que no tienen esa capacidad por la realización de otras máscercanas al modelo de rendimiento del triatlón

On the processing time for detection of Skype traffic

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. [P. M. Santiago del Río. J. Ramos, J. L. García-Dorado, J. Aracil, A. Cuadra-Sánchez, and M. Cutanda-Rodríguez, "On the processing time for detection of Skype traffic", in 7th International Wireless Communications and Mobile Computing Conference, IWCMC 2011, p. 1784 - 1788The last few years have witnessed VoIP applications gaining a tremendous popularity and Skype, in particular, is leading this continuous expansion. Unfortunately, Skype follows a closed source and proprietary design, and typically uses encryption mechanisms, making it very difficult to identify its presence from a traffic aggregate. Several algorithms and approaches have been proposed to perform such task with promising results in terms of accuracy. However, such approaches typically require significant computation resources and it is unlikely that they can be deployed in nowadays high-speed networks. In this light, this paper focuses on cutting the processing cost of algorithms to detect Skype traffic. We have conveniently tuned a previous well-validated algorithm and we have assessed its performance. To this end, we have used real traces from public repositories, from a Spanish 3G operator, and synthetic traces. Our results show that a single process can detect Skype traffic at 1 Gbps rates reading replayed real traces directly from a NIC. Even more, 3.7 Gbps are achieved reading from traces previously allocated in memory using a single process and 45 Gbps using 16 concurrent processes. This fact paves the way for 10 Gbps processing in commodity hardware

Educación y cooperación para el desarrollo mediante estándares universales de accesibilidad

II FORO «IBEROAMÉRICA EN LA ESCENA ECONÓMICA INTERNACIONAL: INVERSIONES Y EDUCACIÓN PARA EL DESARROLLO». UNIVERSIDAD REY JUAN CARLOS, MADRID (ESPAÑA), 14 DE DICIEMBRE DE 200

Accesibilidad a Internet: requisitos para la calidad en la docencia e investigación

A good Internet platform for teaching and research must be accessible, independently of the computer platform used, language and other peculiarities (personal or external). This work analyzes the current limitations of Internet access, as well as the potentialities that would represent an access being truly independent of the computer platform, discapacities, availability and speed of access, language and legislation. Thus, the benefits for a more accesible network for lecturing and investigation, overcoming the geographic location or possible discapacity, would be immediate and would have a broad impact spectrum. A more accesible Internet would enhace not only the dissemination of the information, approaching us to the 'global village', but also others aspects like university principles and values that sould be considered: an improvement of the equality of opportunities and the access to the culture and the education, that are the basis of the progress and the individual and collective liberties.Una buena plataforma de docencia e investigación en la red debe ser accesible, independientemente del entorno informático, idioma y condicionantes( personales o externos). Es este trabajo se analizan, por una parte, las limitaciones actuales que se presentan en el acceso a Internet, y por otra las potencialidades que tendría un acceso un acceso independiente de las plataforma informáticas, discapacidades, disponibilidad y velocidad de acceso, idioma y legislación. Así, los beneficios para la docencia y la investigación de una red más accesible, por encima de la localización geográfica o posible discapacidad, serán inmediatos y redundaría en otros campos. Una Internet más accesible abriría una nueva vía no sólo para la difusión de la información, acercándonos a la 'aldea global', sino también para otros aspectos de lo que entenderemos como principios y valores universitarios y que deben ser considerados: una mejora en la igualdad de oportunidades y en el acceso a la cultura y la formación, que son las bases del progreso y de las libertades tanto individuales como colectivas