Towards a virtualized Internet for computer networking assignments

By combining virtualization technologies, virtual private network techniques and parameterization of network scenarios it is possible to enhance a networking laboratory, typically carried out in university laboratory premises using equipment located there, by interconnecting it to virtual networks running on the students own personal computers. This paper describes some experiences applying this model to create hands-on assignments for a large group of students in computer networking education

Colaboración de herramientas mediante interfaces basadas en Servicios Web: la aplicación de videoconferencia Marte

El documento detalla la arquitectura ideada dentro del proyecto europeo ECOSPACE para la interoperabilidad de las herramientas de los e-Profesionales, empleando una aproximación orientada a servicios. Cada aplicación de un entorno de trabajo colaborativo debe ofrecer interfaces basadas en servicios web; en particular aquí se contempla el caso de la videoconferencia, como ejemplo representativo de sistema de funcionalidades avanzadas. Adicionalmente, los distintos servicios pueden componerse y orquestarse para ofrecer otros de mayor complejidad; para demostrar la flexibilidad y potencia de esta solución, se incluye un ejemplo que involucra múltiples herramientas. Finalmente, se contempla la posibilidad de usar otro tipo de interfaces, más extendidas actualmente, pero que implicarían un cambio profundo en la arquitectura y, por tanto, en las aplicaciones

From Inflammation to the Onset of Fibrosis through A2A Receptors in Kidneys from Deceased Donors.

Pretransplant graft inflammation could be involved in the worse prognosis of deceased donor (DD) kidney transplants. A2A adenosine receptor (A2AR) can stimulate anti-inflammatory M2 macrophages, leading to fibrosis if injury and inflammation persist. Pre-implantation biopsies of kidney donors (47 DD and 21 living donors (LD)) were used to analyze expression levels and activated intracellular pathways related to inflammatory and pro-fibrotic processes. A2AR expression and PKA pathway were enhanced in DD kidneys. A2AR gene expression correlated with TGF-β1 and other profibrotic markers, as well as CD163, C/EBPβ, and Col1A1, which are highly expressed in DD kidneys. TNF-α mRNA levels correlated with profibrotic and anti-inflammatory factors such as TGF-β1 and A2AR. Experiments with THP-1 cells point to the involvement of the TNF-α/NF-κB pathway in the up-regulation of A2AR, which induces the M2 phenotype increasing CD163 and TGF-β1 expression. In DD kidneys, the TNF-α/NF-κB pathway could be involved in the increase of A2AR expression, which would activate the PKA-CREB axis, inducing the macrophage M2 phenotype, TGF-β1 production, and ultimately, fibrosis. Thus, in inflamed DD kidneys, an increase in A2AR expression is associated with the onset of fibrosis, which may contribute to graft dysfunction and prognostic differences between DD and LD transplants

Modelización de sistemas de comunicación de grupo

El trabajo desarrollado se centra en el estudio de los procesos y esquemas de comunicación que deben mantener grupos de personas interesadas en alcanzar objetivos comunes o desarrollar un trabajo en cooperación, con la particularidad de que la comunicación se realiza a través de un medio electrónico, el ordenador. La ausencia de herramientas y modelos adecuados para analizar y describir tales esquemas de comunicación en el entorno electrónico, es una de las causas que más ha dificultado el desarrollo de sistemas que satisfagan la demanda creciente de soporte para las actividades de comunicación en un grupo. Los sistemas de comunicación electrónica que en la actualidad están siendo utilizados masivamente, sobre todo en el entorno académico y de investigación (correo electrónico, conferencia electrónica, listas de distribución, etc.) y con un éxito considerable, responden a unos patrones básicos e informales, adecuados al tipo de comunicación no estructurada que se establece en este y otros entornos. Sin embargo, no proporcionan la suficiente flexibilidad como para responder a procesos de comunicación más estructurados, regulados de acuerdo al medio y en donde se conjuguen los elementos básicos de todo esquema de comunicación. Según este planteamiento, se establece en el trabajo de tesis un marco genérico para la descripción de los procesos de comunicación de grupo en un medio electrónico, que pueda ser utilizado para analizar, representar y especificar los distintos esquemas que se producen en situaciones plurales de comunicación y que cree asimismo unas bases genéricas sobre las que los grupos puedan adaptar y establecer sus formas de comunicación óptimas. El marco se expresa en un modelo que integra los objetos relevantes del dominio y sus interrelaciones. La conceptualización que da paso al modelo es posible ya que existen estructuras comunes que subyacen en las diversas situaciones o escenarios de comunicación. El modelo define una "actividad" como un proceso de intercambio de información dentro de un grupo que persigue objetivos comunes. En una actividad, las entidades comunicantes a las que se les asigna un rol, efectúan operaciones sobre los mensajes que se intercambian. El comportamiento del comunicante/rol está dirigido por unas reglas que le marcan qué operaciones puede ejecutar sobre qué mensajes. Una actividad concreta será el resultado de describir los detalles específicos de cada uno de los objetos siguiendo las pautas dadas en el esquema abstracto del modelo. Se obtiene así un grupo concreto que establece una determinada actividad de comunicación por medio de roles, mensajes, operaciones y unas reglas de coordinación. Analizado el modelo, se realiza a continuación una propuesta de arquitectura que integra los componentes del modelo en el marco distribuido de OSI. Se identifican entonces dos clases de entidades que soportarán la aplicación distribuida de la comunicación de grupo y que proporcionarán a los comunicantes la funcionalidad requerida: el Agente de Actividad y el Agente de Rol. El primero de ellos se encarga de supervisar y conducir el proceso global de comunicación en una actividad. El segundo está asociado al usuario y se comunica con él a través de un conjunto de primitivas. Se plantea una alternativa de diseño del agente de actividad de forma que se distribuye totalmente el conocimiento que mantiene, entre los distintos agentes de rol que realizan la función de soporte de los comunicantes. Este diseño requiere un conjunto de agentes inteligentes autónomos cooperando con el fin de cumplir una actividad. Cada agente de rol necesitaría entonces de una base de conocimiento propia que le permitiese tomar decisiones acerca de sus propias estrategias de comunicación y cooperación, basadas en sus responsabilidades de rol. Para ilustrar este diseño distribuido se realiza una implementación sobre un sencillo ejemplo, que muestra además, cómo técnicas de representación del conocimiento importadas desde el campo de la Inteligencia Artificial y conceptos de inteligencia distribuida, pueden proporcionar las bases para el desarrollo de sistemas de comunicación potentes y flexibles.---ABSTRACT---The present work is focused on the study of group communication processes and patterns that human beings hold when they are interested in reaching common goals or in developing a cooperative work, having in mind that the communication is computer-based. The most important reason that have made difficult the develop of group communication systems supporting group activities is the lack of suitable tools and models for describing and analysing such communication patterns in the electronic environment. The current electronic communication systems are used, above all, in the academic and research environments (electronic mail, electronic conference, distribution lists, etc.). They only make up basic and informal patterns, adapted to a kind of unstructured communication typical in that environments. However, they do not provide enough flexibility as it is needed in more structured communication processes, regulated in accordance with the electronic media and using all the elements present in any communication scheme. In this thesis, it is established a generic framework for describing the electronic group communication processes. The framework can be used to analyze, represent and specify the different patterns that arise in different communication situations and also to créate a generic base to allow the groups to establish and adapt their optimal communication forms. The framework is expressed as a model which integrates the relevant domaindependent objects as well as their interrelations. The development of a conceptual model is possible because it has been recognized common structures laying in different communication situations. The model defines an "activity" as a process of information interchange among a group that have common goals. In an activity, the communicator entities play a role and execute operations on interchanged messages. The communicator/rol behaviour is conducted by rules that indícate which operations are to be performed on which messages. An activity instance will be the result of describing the specific details about each of the objects, following the abstract model scheme. In this way, it is obtained a concrete group that establish a specific communication activity by means of roles, messages, operations and coordination rules. An architectural approach is made that try to intégrate the model elements in the OSI distributed environment. Two classes of entities are identified that will serve of support for the distributed group communication application and they will provide the required functionality: the activity agent and the role agent. The former surveys and conducís the global communication process in an activity. The latter is refered to the user and communicates with him through a set of primitives. An activity agent design is proposed where a total distribution of the activity knowledge to all role agents involved in supporting the commumcator is performed. This design requires a number of autonomous intelligent agents cooperating with the aim of fulfilling an activity. Each of the role agents then need its own knowledgebase that allows to take decisions about its own communication and cooperation strategies based on its role responsabilities. To make clear the distributed design a prototype implementation is developed on a simple example and it illustrates that taking representation technics from Artificial Intelligence can provide the basis for powerful computer-based communication and coordination systems

Supporting handover between LTE video broadcasting and unicast streaming

The heterogeneity of the network poses new challenges on the paradigm of multimedia content distribution. Nowadays, different access technologies coexist in user terminals, so it is possible to improve the performance or avoid coverage problems by switching from one to another. This process is known as handover. In this work we have focused on vertical handover, which is the process of switching between different access technologies without losing connectivity. If a handover happens during a video streaming session, the session will need to adapt to the different channel conditions. This paper discusses the proposal of a new mechanism at the application level to support a handover between a unicast video streaming session and a video session based on LTE broadcasting

DASH Adaptation Algorithm Based on Adaptive Forgetting Factor Estimation

The wide adoption of multimedia service-capable mobile devices, the availability of better networks with higher bandwidths, and the availability of platforms offering digital content has led to an increasing popularity of multimedia streaming services. However, multimedia streaming services can be subject to different factors that affect the quality perceived by the users, such as service interruptions or quality oscillations due to changing network conditions, particularly in mobile networks. Dynamic Adaptive Streaming over HTTP (DASH), leverages the use of content-distribution networks and the capabilities of the multimedia devices to allow multimedia players to dynamically adapt the quality of the media streaming to the available bandwidth and the device characteristics. While many elements of DASH are standardized, the algorithms providing the dynamic adaptation of the streaming are not. The adaptation is often based on the estimation of the throughput or a buffer control mechanism. In this paper, we present a new throughput estimation adaptation algorithm based on a statistical method named Adaptive Forgetting Factor (AFF). Using this method, the adaptation logic is able to react appropriately to the different conditions of different types of networks. A set of experiments with different traffic profiles show that the proposed algorithm improves video quality performance in both wired and wireless environments

Reduced adenosine uptake and its contribution to signaling that mediates profibrotic activation in renal tubular epithelial cells: implication in diabetic nephropathy.

Altered nucleoside levels may be linked to pathogenic signaling through adenosine recep- tors. We hypothesized that adenosine dysregulation contributes to fibrosis in diabetic kid- ney disease. Our findings indicate that high glucose levels and experimental diabetes decreased uptake activity through the equilibrative nucleoside transporter 1 (ENT1) in proxi- mal tubule cells. In addition, a correlation between increased plasma content of adenosine and a marker of renal fibrosis in diabetic rats was evidenced. At the cellular level, exposure of HK2 cells to high glucose, TGF- β and the general adenosine receptor agonist NECA, induced the expression of profibrotic cell activation markers α -SMA and fibronectin. These effects can be avoided by using a selective antagonist of the adenosine A 3 receptor subtype in vitro. Furthermore, induction of fibrosis marker α -SMA was prevented by the A 3 receptor antagonist in diabetic rat kidneys. In conclusion, we evidenced the contribution of purinergic signaling to renal fibrosis in experimental diabetic nephropathy

A virtualized platform for analyzing LTE broadcast services

Nowadays, users are demanding access to video content anytime and anywhere. LTE broadcast services and video streaming services can reduce the resources used by telecommunication companies to give access to video content and open up new business opportunities. In this context, testbeds and simulation tools can help in the analysis of the different parameters that need to be considered in the deployment of video services based on LTE. In this paper, we describe the design and implementation of an open-source virtualized platform that supports both LTE broadcast services and video streaming services. The testbed is being used both over real LTE networks and LTE network emulations to analyze the performance of video streaming services and to validate new proposals

Alfa : método de lectura-escritura para adultos

Contiene: Guía didáctica; Bloque 1, primera parte; Bloque 1, segunda parte; Bloque 2, primera parte; y Bloque 2, segunda parteMétodo de lecto-escritura organizado en fichas de trabajo para alumnos del nivel de Alfabetización.MadridBiblioteca de Educación del Ministerio de Educación, Cultura y Deporte; Calle San Agustín 5 -3 Planta; 28014 Madrid; Tel. +34917748000; [email protected]