Abstract
Network operators have been reluctant to deploy IP multicast services mainly due to the lack of native control rover multicast groups. This lack of control does not only prevent operators from generating revenue from multicast-based services but also hinders regular network management. In this work we identified the network elements where admission control should be enforced for multicast session spawning over heterogeneous access networks. The architecture proposed uses existing AAA functionality to perform user identification and multicast session admission control. This control is made at the network layer with no protocol modifications. Three access networks were considered: xDSL, WiMAX and UMTS.

Abstract
Technological evolution is leading telecommunications toward all-IP scenarios, where multiple services are transported as IP packets. Among these services is the broadcast of video. A possible mechanism for broadcasting multiple video channels over IP is to use IP multicast, and let each client decide about the reception of a channel. The secure IP multicast specified by the IETF MSEC working group is a candidate solution for securing these broadcast services. In this paper we propose a new solution for supporting the broadcast of multiple video channels which can be accessed only by authorized users; besides, when a video channel is not visualized in the last mile its transmission is temporarily suspended, so that the cable can be used for other services such as standard Internet access.

Abstract
Learning objects are not a new concept, being currently produced either according to existent specifications, or in an ad hoc way. However, a system that can easily classify them for automatic storage is still missing In this article we propose a repository of learning objects which is capable of automatic classification and categorization based on a semantic organization. The classification is based on a text extraction mechanism which then uses text mining methods. We present a methodology for the initial clustering of objects, and a technique for maintaining the organization with continuous arrival of new objects.

Abstract
The general available tools for analyzing interactions in online discussion forums appear to be insufficient to characterize groups of medium/large dimensions, as they are limited to provide general information of participation, access statistics and message posting. Our research contributes for analyzing and characterizing asynchronous online interactions applying the Social Network Analysis methodology, by providing e-learning platforms with an interactive graph - the iGraph - that illustrates, and analyses, students' interactions. In a graphical interface embedded in an open source learning management system we combine real-time graphs and numerical indicator to provide the educator with a more thorough understanding of relations between course participants. Preliminary results indicate that the iGraph enables an insightful characterization of the interactions between actors and their participations in discussion forums.

Abstract
In this paper we present the architecture of RTPM, a middle-ware framework aimed at supporting the development and management of information systems for high-speed public transportation systems. The framework is based on a peer-to-peer overlay infrastructure with the main focus being on providing a scalable, resilient, reconfigurable, highly available platform for real-time and QoS computing. Copyright 2008 ACM.

Abstract
AGILMAT is a web application designed to help students learn Mathematics, with focus on high-school algebra and calculus drills. A modular and extensible architecture and a wizard-based configuration interface decoupled from the system core are major design features of AGILMAT. The drill expressions are specified by grammars and constraints imposed by default profiles and user options, so that AGILMAT may support distinct learning levels and stages. The core system uses symbolic manipulation and automated reasoning to provide correct answers for the drills. The paper shows how AGILMAT may be used to create and customize drills automatically.