CRYPT4YOU y la utilidad de los MOOCs en la formación online en lengua española.

En los últimos dos años la formación online ha experimentado un auge significativo gracias al paradigma de formación denominado MOOC (Massive Open Online Course). Un MOOC simplifica la formación a distancia gracias a sus características de abierto, colaborativo, masivo y gratuito. Por desgracia en lengua española la utilización de este tipo de recurso formativo todavía es minoritaria. La presente investigación recoge una experiencia de innovación educativa en la que se destaca el diseño, implementación y difusión del primer MOOC en lengua española dedicado a la seguridad de la información por parte de la Universidad Politécnica de Madrid. Esta experiencia aborda las ventajas e inconvenientes de este tipo de recurso formativo, debatiendo aspectos vitales para la elaboración prolongada de cursos tipo MOOC, como son la interactividad y retroalimentación con los usuarios del curso o la forma más adecuada de representar el contenido docente. Todas estas cuestiones reciben respuesta en el MOOC Crypt4you, que con más de 10 meses de vida permite vislumbrar un gran éxito de este tipo de cursos en la formación, al menos en lengua española, de hispanohablantes. ABSTRACT In the last two years, online training has boomed thanks to significant training paradigm called MOOC (Massive Open Online Course). A MOOC simplifies remote training thanks to its open, collaborativend free mass features. Unfortunately, the use of this kind of learning resource in Spanish teaching is still a minority. This research includes an educational experience which emphasizes the design, implementation and dissemination of the first Spanish-language MOOC devoted to information security by the Technical University of Madrid. This experiment addresses the advantages and disadvantages of this kind of learning resource discussing critical issues for developing type MOOC prolonged courses, such as interactivity and feedback from users of the course or the most appropriate way of representing the educational content. All these questions are answered in the MOOC Crypt4you which, over its 10 months of life, can glimpse a great success of this type of training course, at least in Spanish, Spanish-speakers.

A scalable approach for content based image retrieval in cloud datacenter

The emergence of cloud datacenters enhances the capability of online data storage. Since massive data is stored in datacenters, it is necessary to effectively locate and access interest data in such a distributed system. However, traditional search techniques only allow users to search images over exact-match keywords through a centralized index. These techniques cannot satisfy the requirements of content based image retrieval (CBIR). In this paper, we propose a scalable image retrieval framework which can efficiently support content similarity search and semantic search in the distributed environment. Its key idea is to integrate image feature vectors into distributed hash tables (DHTs) by exploiting the property of locality sensitive hashing (LSH). Thus, images with similar content are most likely gathered into the same node without the knowledge of any global information. For searching semantically close images, the relevance feedback is adopted in our system to overcome the gap between low-level features and high-level features. We show that our approach yields high recall rate with good load balance and only requires a few number of hops.

Técnicas de Gamification para entregas de trabajos online: comprobaciones de la fase de análisis de la compilación

Este Trabajo de Fin de Grado (TFG) tiene el objetivo de aportar un sistema de enseñanza innovador, un sistema de enseñanza mediante el cual se consiga involucrar a los alumnos en tareas y prácticas en las que se adquieran conocimientos a la vez que se siente un ambiente de juego, es decir, que se consiga aprender de forma divertida. Está destinado al sistema educativo de la Escuela Técnica Superior de Ingenieros Informáticos de la Universidad Politécnica de Madrid, en concreto a las asignaturas relacionadas con los Procesadores de Lenguajes. La aplicación desarrollada en este trabajo está destinada tanto a los profesores de las asignaturas de Procesadores de Lenguajes como a los alumnos que tengan alguna relación con esas asignaturas, consiguiendo mayor interacción y diversión a la hora de realizar la tareas y prácticas de las asignaturas. Para los dos tipos de usuarios descritos anteriormente, la aplicación está configurada para que puedan identificarse mediante sus credenciales, comprobándose si los datos introducidos son correctos, y así poder acceder al sistema. Dependiendo de qué tipo de usuario se identifique, tendrá unas opciones u otras dentro del sistema. Los profesores podrán dar de alta, ver, modificar o dar de baja las configuraciones para los analizadores de los lenguajes correspondientes a las diferentes asignaturas que están configurados previamente en el sistema. Además, los profesores pueden dar de alta, ver, modificar o dar de baja los fragmentos de código que formarán los ficheros correspondientes a las plantillas de pruebas del analizador léxico que se les ofrece a los alumnos para realizar comprobaciones de las prácticas. Mediante la aplicación podrán establecer diferentes características y propiedades de los fragmentos que incorporen al sistema. Por otra parte, los alumnos podrán realizar la configuración del lenguaje, definido por los profesores, para la parte del analizador léxico de las prácticas. Esta configuración será guardada para el grupo al que corresponde el alumno, pudiendo realizar modificaciones cualquier miembro del grupo. De esta manera, se podrán posteriormente establecer las relaciones necesarias entre los elementos del lenguaje según la configuración de los profesores y los elementos referentes a las prácticas de los alumnos.Además, los alumnos podrán realizar comprobaciones de la parte léxica de sus prácticas mediante los ficheros que se generan por el sistema en función de sus opciones de práctica y los fragmentos añadidos por los profesores. De esta manera, se informará a los alumnos del éxito de las pruebas o bien de los fallos ocasionados con sus resultados, bien por el formato del archivo subido como resultado de la prueba o bien por el contenido incorrecto de este mismo. Todas las funciones que ofrece esta aplicación son completamente on-line y tendrán una interfaz llamativa y divertida, además de caracterizarse por su facilidad de uso y su comodidad. En el trabajo realizado para este proyecto se cumplen tanto las Pautas de Accesibilidad para Contenidos Web (WCAG 2.0), así como las propiedades de un código HTML 5 y CSS 3 de manera correcta, para así conseguir que los usuarios utilicen una aplicación fácil, cómoda y atractiva.---ABSTRACT---This Final Year Project (TFG) aims to contribute the educational system of the School of Computer Engineering at the Polytechnic University of Madrid, especially in subjects related with Language Processors. This project is an interactive learning system whose goal is to learn in an amusing environment. To realize this target, the system involves students, using environments of games in tasks and practices. The application developed in this project is designed for both professors of the subjects of Language Processors and students who have some relation to these subjects. This perspective achieve more interaction and a funny environment during the subject‘s tasks. The application is configured in order to the users can be identified by their credentials, checking whether the identification data are correct to have access to the system. According on what type of user is identified, they will have different options within the system. Professors will be able to register, modify or delete settings for the scanner of languages for all the subjects preconfigured in the system. Additionally, professors can register, show, modify or remove the code of the templates from scanner tests that are offered to students for testing the practical exercises. The professors may provide also different characteristics and properties of fragments incorporated in the system. Moreover, students can make the configuration of languages, getting in the systems by the administrators, for the scanner module of their practical exercises. This configuration will be saved for the group of the student. This model can also be changed by any group member. The system permits also establish later the relationships between the elements of language fixes by professors and elements developed by the students. Students could check the lexical part of their practical exercises through files that are created according to their practical options and the fragments added by professors. Thus students will be informed of success or failure in the uploaded files format and in the content of them. All functions provide by this application are completely on-line and will have a striking and funny interface, also characterized by its ease of use and comfort.The work reaches both the Web Content Accessibility Guidelines (WCAG 2.0), and the properties of an HTML 5 and CSS 3 code correctly, in order to get the users to get an easy, convenient application and attractive.

HispaVeg: a new online vegetation plot database for Spain

We describe a new online database, named HispaVeg, which currently holds data from 2663 vegetation plots of Spanish woodlands, scrublands and grasslands. Unlike other similar databases, a detailed description of the structure is stored with the floristic data of each plot (i.e., number and physiognomy of the vertical layers, cover values for each layer).Most of the vegetation plots are large rectangles (400 to 2000 square meters) with an average of 34 species per plot. The survey dates range from 1956 to present, with most of the records between 1964 and 1994. The elevation of the plots ranges from 0 to 2880, with most of the plots between 300 and 1500 m. HispaVeg is freely available to the scientific community. Users can query the online database, view printable reports for each plot and download spreadsheet-like raw data for subsets of vegetation plots.

Content Delivery System for Optimal VoD Streaming

The demand of video contents has rapidly increased in the past years as a result of the wide deployment of IPTV and the variety of services offered by the network operators. One of the services that has especially become attractive to the customers is real-time video on demand (VoD) because it offers an immediate streaming of a large variety of video contents. The price that the operators have to pay for this convenience is the increased traffic in the networks, which are becoming more congested due to the higher demand for VoD contents and the increased quality of the videos. As a solution, in this paper we propose a hierarchical network system for VoD content delivery in managed networks, which implements redistribution algorithm and a redirection strategy for optimal content distribution within the network core and optimal streaming to the clients. The system monitors the state of the network and the behavior of the users to estimate the demand for the content items and to take the right decision on the appropriate number of replicas and their best positions in the network. The system's objectives are to distribute replicas of the content items in the network in a way that the most demanded contents will have replicas closer to the clients so that it will optimize the network utilization and will improve the users' experience. It also balances the load between the servers concentrating the traffic to the edges of the network.

Las presentaciones de trabajo en lengua inglesa: una propuesta de curso on-line.

Desde la explosión de crecimiento de internet que comenzó en los años 90, se han ido creando y poniendo a disposición de los usuarios diversas herramientas para compartir información y servicios de diversas formas, desde el nacimiento del primer navegador hasta nuestros días, donde hay infinidad de lenguajes aplicables al ámbito web. En esta fase de crecimiento, en primer lugar, de cara a usuarios individuales, saldrían herramientas que permitirían a cada cual hacer su web personal, con sus contenidos expuestos. Más adelante se fue generando el fenómeno “comunidad”, con, por ejemplo, foros, o webs en las que había múltiples usuarios que disfrutaban de contenidos o servicios que la web ofreciese. Este crecimiento del mundo web en lo comunitario ha avanzado en muchas ramas,entre ellas, por supuesto, la educacional, surgiendo plataformas como la que es base del proyecto que a continuación se presenta, y herramienta básica y prácticamente ya imprescindible en la enseñanza universitaria: Moodle. Moodle es una herramienta diseñada para compatir recursos y diseñar actividades para el usuario potencial, complementando su aprendizaje en aula, o incluso siendo una vía autónoma de aprendizaje en sí misma. Se ha realizado un estudio sobre el estado de saludo de los contenidos que se exponen en Moodle, y se ha encontrado que una gran mayoría de los cursos que se pueden visitar tienen un gran número de carencias. Por un lado, hay pocos con material original explotado exclusivamente para el curso, y, si tienen material original, no se ha observado una especial atención por la maquetación. Por otro lado, hay muchos otros sin material original, y, en ambos casos, no se ha encontrado ningún curso que ofrezca material audiovisual exclusivo para el curso, presentando algunos en su lugar material audiovisual encontrado en la red (Youtube, etc). A la vista de estos hechos, se ha realizado un proyecto que intenta aportar soluciones ante estas carencias, y se presenta un curso procedente de diversas referencias bibliográficas, para la parte textual, y material audiovisual original e inédito que también se ha explotado específicamente para este curso. Este material ha sido por un lado vídeo, que se ha visionado, editado y subtitulado con software de libre distribución, y por otro lado, audio, que complementa un completo glosario que se ha añadido como extra al curso y cuyo planteamiento no se ha encontrado en ningún curso online de los revisados. Todo esto se ha envuelto en una maquetación cuidada que ha sido fruto del estudio de los lenguajes web html y CSS, de forma que, por un lado, el curso sea un lugar agradable en el que aprender dentro de internet, y por otro, se pudiesen realizar ciertas operaciones que sin estos conocimientos habrían sido imposibles, como la realización del glosario o la incrustación de imágenes y vídeos. A su vez, se ha tratado de dar un enfoque didáctico a toda la memoria del proyecto, de forma que pueda ser de utilidad a un usuario futuro que quisiese profundizar en los usos de Moodle, introducirse en el lenguaje web, o introducirse en el mundo de la edición de vídeo. ABSTRACT: Since the explosion of Internet growth beginning in the 90s, many tools have been created and made available for users to share information and services in various ways, from the birth of the first browser until today, where there are plenty of web programming languages. This growth stage would give individual users tools that would allow everyone to make an own personal website, with their contents exposed. Later, the "community" phenomenon appeared with, for example, forums, or websites where multiple users enjoyed the content or web services that those websites offered. Also, this growth in the web community world has progressed in many fields, including education, with the emerge of platforms such as the one that this project uses as its basis, and which is the basic and imperative tool in college education: Moodle. Moodle is a tool designed to share resources and design activities for the potential user, completing class learning, or even letting this user learn in an autonomous way. In this project a study on the current situation of the content present in Moodle courses around the net has been carried out, and it has been found that most of them lack of original material exploited exclusively for the courses, and if they have original material, there has been not observed concern on the layout where that material lies. On the other hand, there are many other with non original material, and in both cases, there has not been found any course that offers audio- visual material made specifically for the course, instead of presenting some audiovisual material found on the net (Youtube, etc). In view of these facts, the project presented here seeks to provide solutions to these shortcomings, presenting a course with original material exploited from various references, and unpublished audioevisual material which also has been exploited specifically for this course. This material is, on one hand, video, which has been viewed, edited and subtitled with free software, and on the other, audio, which complements a comprehensive glossary that has been added as an extra feature to the course and whose approach was not found in any of the online courses reviewed. All of this has been packaged in a neat layout that has been the result of the study of web languages HTML and CSS, so that first, the course was a pleasant place to learn on the internet, and second, certain operations could be performed which without this knowledge would have been impossible, as the glossary design or embedding images and videos. Furthermore, a didactic approach has been adopted to the entire project memory, so it can be useful to a future user who wanted to go deeper on the uses of Moodle, containing an intro into the web language, or in the world video editing.

Social and content hybrid image recommender system for mobile social networks

One of the advantages of social networks is the possibility to socialize and personalize the content created or shared by the users. In mobile social networks, where the devices have limited capabilities in terms of screen size and computing power, Multimedia Recommender Systems help to present the most relevant content to the users, depending on their tastes, relationships and profile. Previous recommender systems are not able to cope with the uncertainty of automated tagging and are knowledge domain dependant. In addition, the instantiation of a recommender in this domain should cope with problems arising from the collaborative filtering inherent nature (cold start, banana problem, large number of users to run, etc.). The solution presented in this paper addresses the abovementioned problems by proposing a hybrid image recommender system, which combines collaborative filtering (social techniques) with content-based techniques, leaving the user the liberty to give these processes a personal weight. It takes into account aesthetics and the formal characteristics of the images to overcome the problems of current techniques, improving the performance of existing systems to create a mobile social networks recommender with a high degree of adaptation to any kind of user.

Developing front-end Web 2.0 technologies to access services, content and things in the future Internet

The future Internet is expected to be composed of a mesh of interoperable web services accessible from all over the web. This approach has not yet caught on since global user?service interaction is still an open issue. This paper states one vision with regard to next-generation front-end Web 2.0 technology that will enable integrated access to services, contents and things in the future Internet. In this paper, we illustrate how front-ends that wrap traditional services and resources can be tailored to the needs of end users, converting end users into prosumers (creators and consumers of service-based applications). To do this, we propose an architecture that end users without programming skills can use to create front-ends, consult catalogues of resources tailored to their needs, easily integrate and coordinate front-ends and create composite applications to orchestrate services in their back-end. The paper includes a case study illustrating that current user-centred web development tools are at a very early stage of evolution. We provide statistical data on how the proposed architecture improves these tools. This paper is based on research conducted by the Service Front End (SFE) Open Alliance initiative.

Crowdsourcing malaria parasite quantification: an online game for analyzing images of infected thick blood smears

Background: There are 600,000 new malaria cases daily worldwide. The gold standard for estimating the parasite burden and the corresponding severity of the disease consists in manually counting the number of parasites in blood smears through a microscope, a process that can take more than 20 minutes of an expert microscopist’s time. Objective: This research tests the feasibility of a crowdsourced approach to malaria image analysis. In particular, we investigated whether anonymous volunteers with no prior experience would be able to count malaria parasites in digitized images of thick blood smears by playing a Web-based game. Methods: The experimental system consisted of a Web-based game where online volunteers were tasked with detecting parasites in digitized blood sample images coupled with a decision algorithm that combined the analyses from several players to produce an improved collective detection outcome. Data were collected through the MalariaSpot website. Random images of thick blood films containing Plasmodium falciparum at medium to low parasitemias, acquired by conventional optical microscopy, were presented to players. In the game, players had to find and tag as many parasites as possible in 1 minute. In the event that players found all the parasites present in the image, they were presented with a new image. In order to combine the choices of different players into a single crowd decision, we implemented an image processing pipeline and a quorum algorithm that judged a parasite tagged when a group of players agreed on its position. Results: Over 1 month, anonymous players from 95 countries played more than 12,000 games and generated a database of more than 270,000 clicks on the test images. Results revealed that combining 22 games from nonexpert players achieved a parasite counting accuracy higher than 99%. This performance could be obtained also by combining 13 games from players trained for 1 minute. Exhaustive computations measured the parasite counting accuracy for all players as a function of the number of games considered and the experience of the players. In addition, we propose a mathematical equation that accurately models the collective parasite counting performance. Conclusions: This research validates the online gaming approach for crowdsourced counting of malaria parasites in images of thick blood films. The findings support the conclusion that nonexperts are able to rapidly learn how to identify the typical features of malaria parasites in digitized thick blood samples and that combining the analyses of several users provides similar parasite counting accuracy rates as those of expert microscopists. This experiment illustrates the potential of the crowdsourced gaming approach for performing routine malaria parasite quantification, and more generally for solving biomedical image analysis problems, with future potential for telediagnosis related to global health challenges.

Using online presence to improve online collaborative learning

Social software tools have become an integral part of students? personal lives and their primary communication medium. Likewise, these tools are increasingly entering the enterprise world (within the recent trend known as Enterprise 2.0) and becoming a part of everyday work routines. Aiming to keep the pace with the job requirements and also to position learning as an integral part of students? life, the field of education is challenged to embrace social software. Personal Learning Environments (PLEs) emerged as a concept that makes use of social software to facilitate collaboration, knowledge sharing, group formation around common interests, active participation and reflective thinking in online learning settings. Furthermore, social software allows for establishing and maintaining one?s presence in the online world. By being aware of a student's online presence, a PLE is better able to personalize the learning settings, e.g., through recommendation of content to use or people to collaborate with. Aiming to explore the potentials of online presence for the provision of recommendations in PLEs, in the scope of the OP4L project, we have develop a software solution that is based on a synergy of Semantic Web technologies, online presence and socially-oriented learning theories. In this paper we present the current results of this research work.

e-MIR2: a public online inventory of medical informatics resources

Background. Over the last years, the number of available informatics resources in medicine has grown exponentially. While specific inventories of such resources have already begun to be developed for Bioinformatics (BI), comparable inventories are as yet not available for Medical Informatics (MI) field, so that locating and accessing them currently remains a hard and time-consuming task. Description. We have created a repository of MI resources from the scientific literature, providing free access to its contents through a web-based service. Relevant information describing the resources is automatically extracted from manuscripts published in top-ranked MI journals. We used a pattern matching approach to detect the resources? names and their main features. Detected resources are classified according to three different criteria: functionality, resource type and domain. To facilitate these tasks, we have built three different taxonomies by following a novel approach based on folksonomies and social tagging. We adopted the terminology most frequently used by MI researchers in their publications to create the concepts and hierarchical relationships belonging to the taxonomies. The classification algorithm identifies the categories associated to resources and annotates them accordingly. The database is then populated with this data after manual curation and validation. Conclusions. We have created an online repository of MI resources to assist researchers in locating and accessing the most suitable resources to perform specific tasks. The database contained 282 resources at the time of writing. We are continuing to expand the number of available resources by taking into account further publications as well as suggestions from users and resource developers.

Influence of the semantic content of urban sounds in the identity of outer spaces

This paper shows the influence of the semantic content of urban sounds in the subjective evaluation of outer spaces. The study is based on the analysis conducted in three neighboring and integrated urban spaces with a different form of social ownership in the city of Cordoba, Argentina. It shows that the type of sound source present at each site influence, by its semantic content, in the user´s identification and permanence in the place. The noise present in a soundscape is able to have a high semantic content, and therefore the sound has a particular meaning for the perceiver. Every particular social group influences the production of their own sounds and how they perceive them. This allows to consider the sound as one of the factors that define the sense of "place" or "no place" of a certain urban space. Evidently the sounds, and their ability to evoke and characterize the environment, cannot be ignored in the construction and recovery of anthropological sites. This urban culture is unique and specific to every society. Thepublic spaces, with their soundscape, are part of the construction of the urban identity of a city. It is shown that for identical general sound levels present in each of the spaces, the level of annoyance or discomfort, in relation to the subjective acoustic quality, is different. This is the result of the influence of semantic content of the sounds present in each urban space. Coinciding with other similar research, the level of discomfort or annoyance decreases as the presence of natural sounds such as water, the wind in the trees or the birds singing increases, even when the objective values of noise level of natural sounds are higher.

Architectures for Video-on-Demand content distribution in managed networks

La demanda de contenidos de vídeo ha aumentado rápidamente en los últimos años como resultado del gran despliegue de la TV sobre IP (IPTV) y la variedad de servicios ofrecidos por los operadores de red. Uno de los servicios que se ha vuelto especialmente atractivo para los clientes es el vídeo bajo demanda (VoD) en tiempo real, ya que ofrece una transmisión (streaming) inmediata de gran variedad de contenidos de vídeo. El precio que los operadores tienen que pagar por este servicio es el aumento del tráfico en las redes, que están cada vez más congestionadas debido a la mayor demanda de contenidos de VoD y al aumento de la calidad de los propios contenidos de vídeo. Así, uno de los principales objetivos de esta tesis es encontrar soluciones que reduzcan el tráfico en el núcleo de la red, manteniendo la calidad del servicio en el nivel adecuado y reduciendo el coste del tráfico. La tesis propone un sistema jerárquico de servidores de streaming en el que se ejecuta un algoritmo para la ubicación óptima de los contenidos de acuerdo con el comportamiento de los usuarios y el estado de la red. Debido a que cualquier algoritmo óptimo de distribución de contenidos alcanza un límite en el que no se puede llegar a nuevas mejoras, la inclusión de los propios clientes del servicio (los peers) en el proceso de streaming puede reducir aún más el tráfico de red. Este proceso se logra aprovechando el control que el operador tiene en las redes de gestión privada sobre los equipos receptores (Set-Top Box) ubicados en las instalaciones de los clientes. El operador se reserva cierta capacidad de almacenamiento y streaming de los peers para almacenar los contenidos de vídeo y para transmitirlos a otros clientes con el fin de aliviar a los servidores de streaming. Debido a la incapacidad de los peers para sustituir completamente a los servidores de streaming, la tesis propone un sistema de streaming asistido por peers. Algunas de las cuestiones importantes que se abordan en la tesis son saber cómo los parámetros del sistema y las distintas distribuciones de los contenidos de vídeo en los peers afectan al rendimiento general del sistema. Para dar respuesta a estas preguntas, la tesis propone un modelo estocástico preciso y flexible que tiene en cuenta parámetros como las capacidades de enlace de subida y de almacenamiento de los peers, el número de peers, el tamaño de la biblioteca de contenidos de vídeo, el tamaño de los contenidos y el esquema de distribución de contenidos para estimar los beneficios del streaming asistido por los peers. El trabajo también propone una versión extendida del modelo matemático mediante la inclusión de la probabilidad de fallo de los peers y su tiempo de recuperación en el conjunto de parámetros del modelo. Estos modelos se utilizan como una herramienta para la realización de exhaustivos análisis del sistema de streaming de VoD asistido por los peers para la amplia gama de parámetros definidos en los modelos. Abstract The demand of video contents has rapidly increased in the past years as a result of the wide deployment of IPTV and the variety of services offered by the network operators. One of the services that has especially become attractive to the customers is real-time Video on Demand (VoD) because it offers an immediate streaming of a large variety of video contents. The price that the operators have to pay for this convenience is the increased traffic in the networks, which are becoming more congested due to the higher demand for VoD contents and the increased quality of the videos. Therefore, one of the main objectives of this thesis is finding solutions that would reduce the traffic in the core of the network, keeping the quality of service on satisfactory level and reducing the traffic cost. The thesis proposes a system of hierarchical structure of streaming servers that runs an algorithm for optimal placement of the contents according to the users’ behavior and the state of the network. Since any algorithm for optimal content distribution reaches a limit upon which no further improvements can be made, including service customers themselves (the peers) in the streaming process can further reduce the network traffic. This process is achieved by taking advantage of the control that the operator has in the privately managed networks over the Set-Top Boxes placed at the clients’ premises. The operator reserves certain storage and streaming capacity on the peers to store the video contents and to stream them to the other clients in order to alleviate the streaming servers. Because of the inability of the peers to completely substitute the streaming servers, the thesis proposes a system for peer-assisted streaming. Some of the important questions addressed in the thesis are how the system parameters and the various distributions of the video contents on the peers would impact the overall system performance. In order to give answers to these questions, the thesis proposes a precise and flexible stochastic model that takes into consideration parameters like uplink and storage capacity of the peers, number of peers, size of the video content library, size of contents and content distribution scheme to estimate the benefits of the peer-assisted streaming. The work also proposes an extended version of the mathematical model by including the failure probability of the peers and their recovery time in the set of parameters. These models are used as tools for conducting thorough analyses of the peer-assisted system for VoD streaming for the wide range of defined parameters.

Nuevos métodos y herramientas para la creación y utilización de recursos multimedia en la educación

La educación y los entornos educativos están en constante evolución. Tanto alumnos como educadores cambian de hábitos, de maneras de aprender, de gustos, de dispositivos que manejan y de aplicaciones que usan regularmente entre otras cosas. Todos estos cambios vienen acompañados y fomentados en gran medida por la evolución paralela que experimenta la tecnología, tanto software en los programas utilizados, como hardware en los dispositivos y capacidades de éstos. La educación debe también adaptarse a estos cambios, tanto personales como tecnológicos y sacar el mayor provecho de ellos. El uso de Sistemas de Gestión del Aprendizaje está muy extendido en todos los centros educativos. Estos sistemas poseen un gran número de características y funcionalidades que permiten desde la aplicación de un modelo didáctico totalmente tradicional en el que el profesor imparte un contenido y los alumnos lo reciben a uno totalmente innovador en el que ocurren procesos totalmente diferentes. Por otro lado, el potencial que ofrecen los recursos multimedia no ha sido completamente aprovechado en la educación y supone una gran oportunidad. Esta tesis doctoral propone un conjunto de métodos y herramientas para la creación y el uso de recursos multimedia en la educación. Para ello el desarrollo de esta tesis parte de la definición de un modelo didáctico social, colaborativo y centrado en el alumno que servirá de hilo conductor y que integrará los diferentes y métodos y herramientas estudiados y desarrollados. En un primer paso se identifican varias herramientas y métodos para el aula, tales son la grabación de clases, donde se crea y posteriormente se mejora un carrito portátil de grabación que da muy buen resultado, las herramientas de grabación de screencast y la videoconferencia. Estas herramientas además se integran en una plataforma colaborativa dando lugar a una arquitectura completa y escalable que permite la realización de dichas actividades y la interconexión sencilla con el Sistema de Gestión del Aprendizaje. A continuación y ya en un entorno totalmente online se desarrolla una nueva plataforma de e-learning llamada Virtual Science Hub (ViSH) que consta de cuatro funcionalidades principales, red social, videoconferencia, repositorio educativo y herramienta de autor. En esta plataforma se aplicaron técnicas de recomendación proactiva tanto de recursos educativos como de otros usuarios similares. Por último se validó el modelo educativo completo usando algunas de las herramientas identificadas y desarrolladas en dos escenarios diferentes con gran éxito. Finalmente, esta tesis discute las conclusiones obtenidas a lo largo de la extensa investigación llevada a cabo y que ha propiciado la consecución de una buena base teórica y práctica para la creación de herramientas y métodos para la generación y el uso de recursos multimedia en la educación. ABSTRACT Education and learning environments are constantly evolving. Students and educators change the things their habits, their ways of learning, the things they like or the devices and applications that they use regularly among other things. All these changes are accompanied and fostered by the parallel evolution that technology experiences, both in the software programs used as in the hardware and capabilities of these devices. Education must also adapt to these changes, both personal and technological and get the most out of them. Learning Management Systems are widely used in all educational centers. These systems have a large number of features and functionalities. They allow from the implementation of a traditional teaching model in which the teacher gives content and students receive it to one absolutely innovative teaching model where totally different processes occur. Furthermore, the potential of multimedia resources has not been fully exploited in education and can be a great opportunity. This thesis proposes a set of methods and tools for the creation and use of multimedia in education. The development of this thesis starts with the definition of a social, collaborative and learner-centered model, that serves as a common thread and that integrates different tools and methods studied and developed. In a first step, several tools and methods for the classroom are identified, such as recording, where a portable kit is created and then improved giving very good results, screencast recording and videoconferencing. These tools also are integrated into a collaborative platform resulting in a complete, scalable architecture that enables the execution of such activities and a simple interconnection with the Learning Management System. In an fully online environment a new e-learning platform called Virtual Science Hub (ViSH) is created. It consists of four main features that combine and complement each other, social network, videoconferencing, educational repository and authoring tool. In this platform proactive recommendation of both educational resources and similar users is applied. In a last step the entire educational model using some of the tools identified and developed is successfully validated in two different scenarios. Finally, this thesis discusses the findings obtained during the extensive research carried out and has led to the achievement of a good theoretical and practical basis for the development of tools and methods for the generation and use of multimedia in education.

An Online Course on the History of Algorithms.

This paper describes the objectives, content, learning methodology and results of an online course on the History of Algorithms for engineering students at Polytechnic University of Madrid (UPM). This course is conducted in a virtual environment based on Moodle, with a student-centred educational model which includes a detailed planning of learning activities. Our experience indicates that this subject is highly motivating for students and the virtual environment facilitates competencies development