Tecnologías de telecomunicación y educación a distancia en los estados unidos (EE.UU.)

Este artículo pretende describir el uso y las implicaciones de las tecnologías de telecomunicación en la enseñanza a distancia norteamericana. Se ofrece un descripción de la oferta y la demanda de la programación por satélite y cable, las posibles causas del aumento de cursos a distancia en universidades y los contenidos de algunos programas, varias propuestas conceptuales sobre diseños de cursos, y modelos de enseñanza y transmisión en educación a distancia electrónica. Se realiza un examen de la literatura sobre la efectividad instruccional de las tecnologías de telecomunicación y sobre los papeles del profesor a distancia y del tutor. Se discute también el futuro de las tecnologías de telecomunicación

Aprendizaje con la internet: una aproximación critica

En los últimos años, la Internet ha experimentado un crecimiento espectacular y los responsables de la educación de los países desarrollados preconizan su incorporación a todos los niveles de enseñanza. Este articulo propone una reflexión sobre la Internet desde perspectivas que incluyen el análisis de sus implicaciones socioeconómicas y la descripción de las teorías de aprendizaje y resultados de investigación que sustentan su aplicación en el terreno educativo. Él articulo igualmente invita a la consideración de los factores coyunturales que pueden determinar el éxito de tal aplicación

Teletrabajo y recursos humanos en el sector asegurador

Màster de Direcció d'Entitats Asseguradores i Financeres, Universitat de Barcelona, Facultat d'Economia i Empresa, Curs: 2011-2012, Tutor: Pedro Ribes PrecklerEl presente estudio ofrece un análisis global del teletrabajo, considerando que se trata de una modalidad de trabajo que cada vez presenta una mayor penetración en todo tipo de empresa y de sector. Se exponen sus características más importantes, definición y tipología, su evolución y desarrollo en diferentes países, su situación actual a nivel legal y tecnológico. También se realiza un análisis de sus beneficios y desventajas, tanto a nivel de las empresas, como de los empleados y la comunidad. Como objetivo principal del estudio se realiza un enfoque del teletrabajo desde la función de los Recursos Humanos, entendiendo la influencia y la importancia de este departamento para la implantación a las organizaciones de un proyecto de esta magnitud

Valoració del paisatge submarí generat per enclavaments de bioconstruccions, algues esciòfiles i fanerògames marines del sector sud del Golf de València (Mediterrani Occidental)

Els enclavaments de coral·ligen són importants per ser punts calents de biodiversitat a més de ser roques biogèniques pròpies del Mediterrani. Per totes les característiques especials que presenta es du a terme l’estudi del paisatge submarí al sector sud del Golf de València. S’ empren diferents tècniques tal i com l’índex de rugositat del substrat, per a l’avaluació de la complexitat topogràfica, les diferències d’alçada entre les bio concrecions i reconeixements visuals. Aquestes mesures s’han pogut dur a terme en 4 de les 8 localitzacions mostrejades. Els resultats obtinguts han estat les diferències en la complexitat topogràfica entre unes localitzacions i altres i les diferències d’alçades predominants entre unes zones i altres. A més, es poden observar variacions entre les diferents localitzacions tal i com alçada de la vora, relacionada amb l’antiguitat del coral·ligen i la grandària d’aquest.The coralligenous assemblages are important as they are considered biodiversity hot spots in addition to be biogenetic rocks exclusives from Mediterranean Sea. Due to these special characteristics an underwater landscape study is made in a South sector of Valencian Gulf. In order to attain this study, different techniques are used just like Rugosity Index, height differences and visual recognition. These measurements have been made in 4 out of 8 locations studied. The results obtained have been the topographic complexity differences comparing locations and the height differences predominant in distinct locations. Moreover, some differences can be observed in the various locations studied just like edge height which is related with the age and size of the coralligenous.Borrás Palomares, AI. (2016). Valoració del paisatge submarí generat per enclavaments de bioconstruccions, algues esciòfiles i fanerògames marines del sector sud del Golf de València (Mediterrani Occidental). Universitat Politècnica de València. http://hdl.handle.net/10251/75910TFG

Photoelectrochemical water splitting with ITO/WO3/BiVO4/CoPi multishell nanotubes fabricated by soft-templating in vacuum

A well-established procedure for the photoelectrochemical (PEC) splitting of water relies on using porous electrodes of WO3 sensitized with BiVO4 as a visible scavenger photoanode semiconductor. In this work, we propose an evolved photoelectrode fabricated by a soft-template approach consisting of supported multishell nanotubes (NTs). These NTs are formed by a concentric layered structure of indium tin oxide (ITO), WO3, and BiVO4, together with a final film of cobalt phosphate (CoPi) co-catalyst. Photoelectrode manufacturing is easily implemented at large scale and combines thermal evaporation of single crystalline organic nanowires (ONWs), magnetron sputtering (for ITO and WO3), solution dripping, and electrochemical deposition processes (for BiVO4 and CoPi, respectively) plus annealing under mild conditions. The obtained NT electrodes depict a large electrochemically active surface and outperform by more than one order of magnitude the efficiency of equivalent planar-layered electrodes. A thorough electrochemical analysis of the electrodes under blue and solar light illumination demonstrates the critical role of the WO3/BiVO4 Schottky barrier heterojunction in the control of the NT electrode efficiency and its dependence on the BiVO4 outer layer thickness. Oxygen evolution reaction (OER) performance was maximized with the CoPi electrocatalyst, rendering high photocurrents under one sun illumination. The reported results demonstrate the potential of the soft-template methodology for the large area fabrication of highly efficient multishell ITO/WO3/BiVO4/CoPi NT electrodes, or other alternative combinations, for the photoelectrochemical splitting of water.Comment: Manuscript: 39 pages, 8 figures and 1 table. SI: 15 pages, 9 figures and 1 tabl

The impact of User-Browser Interaction on web performance

© ACM 2013. This is the author's version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in ACM, In Proceedings of the 28th Annual ACM Symposium on Applied Computing (pp. 695-702). http://dx.doi.org/10.1145/2480362.2480497The user interaction with the current web contents is a major concern when defining web workloads in order to precisely estimate system performance. However, the intrinsic diffi- culty to represent this behavior in a workload model leads many research works to still use workloads non representative of the current web navigations. In contrast, in previous works we demonstrated that the use of an accurate workload model that considers user’s dynamism when navigating the web clearly affects system performance metrics. In this paper we analyze, for the first time, the effect of considering the User-Browser Interaction (UBI) as a part of user’s dynamic behavior on web workload characterization in performance studies. To this end, we evaluate a typical e-commerce scenario and compare the obtained results for different UBI behaviors, such as the use of the back button and parallel browsing originated by using browser tabs or opening new windows when surfing a website.This work has been partially supported by the Spanish Ministry of Science and Innovation under grant TIN-2009-08201.Peña Ortiz, R.; Gil Salinas, JA.; Sahuquillo Borrás, J.; Pont Sanjuan, A. (2013). The impact of User-Browser Interaction on web performance. ACM. https://doi.org/10.1145/2480362.2480497

Construint l'escola entre tots

Onzenes Jornades de Foment de la Investigació de la FCHS (Any 2005-2006

Superhydrophobic supported Ag-NPs@ZnO-nanorods with photoactivity in the visible range

In this article we present a new type of 1D nanostructures consisting of supported hollow ZnO nanorods (NRs) decorated with Ag nanoparticles (NPs). The 3D reconstruction by high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) electron tomography reveals that the Ag NPs are distributed along the hollow interior of the ZnO NRs. Supported and vertically aligned Ag-NPs@ZnO-NRs grow at low temperature (135 °C) by plasma enhanced chemical vapour deposition on heterostructured substrates fabricated by sputtered deposition of silver on flat surfaces of Si wafers, quartz slides or ITO. The growth mechanisms of these structures and their wetting behavior before and after visible light irradiation are critically discussed. The as prepared surfaces are superhydrophobic with water contact angles higher than 150°. These surfaces turn into superhydrophilic with water contact angles lower than 10° after prolonged irradiation under both visible and UV light. The evolution rate of the wetting angle and its dependence on the light characteristics are related to the nanostructure and the presence of silver embedded within the ZnO NRs. ÂEuropean Union NMP3-CT-2006- 032583Ministerio de Ciencia e Innovación MAT2010-21228, MAT2010-18447, CSD2008-00023Junta de Andalucía P09-TEP-5283, CTS-518

Key factors in web latency savings in an experimental prefetching system

Although Internet service providers and communications companies are continuously offering higher and higher bandwidths, users still complain about the high latency they perceive when downloading pages from the web. Therefore, latency can be considered as the main web performance metric from the user's point of view. Many studies have demonstrated that web prefetching can be an interesting technique to reduce such latency at the expense of slightly increasing the network traffic. In this context, this paper presents an empirical study to investigate the maximum benefits that web users can expect from prefetching techniques in the current web. Unlike previous theoretical studies, this work considers a realistic prefetching architecture using real traces. In this way, the influence of real imple- mentation constraints are considered and analyzed. The results obtained show that web prefetching could improve page latency up to 52% in the studied traces. ©Springer Science+Business Media, LLC 2011De La Ossa Perez, BA.; Sahuquillo Borrás, J.; Pont Sanjuan, A.; Gil Salinas, JA. (2012). Key factors in web latency savings in an experimental prefetching system. Journal of Intelligent Information Systems. 39(1):187-207. doi:10.1007/s10844-011-0188-xS187207391Balamash, A., Krunz, M., & Nain, P. (2007). Performance analysis of a client-side caching/prefetching system for web traffic. Computer Networks, 51(13), 3673–3692.Bestavros, A. (1995). Using speculation to reduce server load and service time on the www. In Proc. of the 4th ACM international conference on information and knowledge management. Baltimore, USA.Bestavros, A., & Cunha, C. (1996). Server-initiated document dissemination for the WWW. In IEEE data engineering bulletin. [Online]. Available: http://citeseer.ist.psu.edu/viewdoc/summary?doi=10.1.1.128.266 . Accessed 29 November 2011.Bouras, C., Konidaris, A., & Kostoulas, D. (2004). Predictive prefetching on the web and its potential impact in the wide area. In World Wide Web: Internet and web information systems (Vol. 7, No. 2, pp. 143–179). The Netherlands: Kluwer Academic.Changa, T., Zhuangb, Z., Velayuthamc, A., & Sivakumara, R. (2008). WebAccel: Accelerating web access for low-bandwidth hosts. Computer Networks, 52(11), 2129–2147.Davison, B. D. (2002). The design and evaluation of web prefetching and caching techniques. Ph.D. dissertation, Rutgers University.de la Ossa, B., Gil, J. A., Sahuquillo, J., & Pont, A. (2007). Delfos: The oracle to predict next web user’s accesses. In Proc. of the IEEE 21st international conference on advanced information networking and applications. Niagara Falls, Canada.de la Ossa, B., Pont, A., Sahuquillo, J., & Gil, J. A. (2010). Referrer graph: A low-cost web prediction algorithm. In Proc. of the 25th ACM symposium on applied computing (pp. 831–838). doi: 10.1145/1774088.1774260 .de la Ossa, B., Sahuquillo, J., Pont, A., & Gil, J. A. (2009). An empirical study on maximum latency saving in web prefetching. In Proc. of the 2009 IEEE/WIC/ACM international conference on web intelligence (WI’09).Dom̀enech, J., Gil, J. A., Sahuquillo, J., & Pont, A. (2006a). DDG: An efficient prefetching algorithm for current web generation. In Proc. of the 1st IEEE workshop on hot topics in web systems and technologies (HotWeb). Boston, USA.Domènech, J., Gil, J. A., Sahuquillo, J., & Pont, A. (2006b). Web prefetching performance metrics: A survey. Performance Evaluation, 63(9–10), 988–1004.Domènech, J., Sahuquillo, J., Gil, J. A., & Pont, A. (2006c). The impact of the web prefetching architecture on the limits of reducing user’s perceived latency. In Proc. of the international conference on web intelligence. Piscataway: IEEE.de la Ossa, B., Gil, J. A., Sahuquillo, J., & Pont, A. (2007). Improving web prefetching by making predictions at prefetch. In Proc. of the 3rd EURO-NGI conference on next generation internet networks design and engineering for heterogeneity (NGI’07) (pp. 21–27).Duchamp, D. (1999). Prefetching hyperlinks. In Proc. of the 2nd USENIX symposium on internet technologies and systems. Boulder, USA.Fan, L., Cao, P., Lin, W., & Jacobson, Q. (1999). Web prefetching between low-bandwidth clients and proxies: Potential and performance. In Proc. of the ACM SIGMETRICS conference on measurement and modeling of computer systems (pp. 178–187).HTTP/1.1. [Online]. Available: http://www.faqs.org/rfcs/rfc2616.html . Accessed 29 November 2011.Kroeger, T. M., Long, D., & Mogul, J. C. (1997). Exploring the bounds of web latency reduction from caching and prefetching. In Proc. of the 1st USENIX symposium on internet technologies and systems. Monterrey, USA.Link prefetching in mozilla faq (2011). [Online]. Available: https://developer.mozilla.org/en/Link_prefetching_FAQ .Markatos, E., & Chronaki, C. (1998). A top-10 approach to prefetching on the web. In Proc. of INET. Geneva, Switzerland.Márquez, J., Domènech, J., Pont, A., & Gil, J. A. (2008). Exploring the benefits of caching and prefetching in the mobile web. In Second IFIP symposium on wireless communications and information technology for developing countries (WCITD 2008).Padmanabhan, V., & Mogul, J. C. (1996). Using predictive prefetching to improve World Wide Web latency. In Proc. of the ACM SIGCOMM conference. Stanford University, USA.Palpanas, T., & Mendelzon, A. (1999). Web prefetching using partial match prediction. In Proc. of the 4th international web caching workshop. San Diego, USA.Schechter, S., Krishnan, M., & Smith, M. D. (1998). Using path profiles to predict http requests. In Proc. of the 7th international World Wide Web conference. Brisbane, Australia.Teng, W., Chang, C., & Chen, M. (2005). Integrating web caching and web prefetching in client-side proxies. IEEE Transactions on Parallel and Distributed Systems, 16(5), 444–455