Abstract
The usage of information and communication technologies has been growing among students and teachers. In order to improve the use of the Internet as a tool to support teaching and learning it is necessary to understand the Internet usage habits of students. Thus, a study was conducted with 1397 students from five schools of the Polytechnic of Porto. The data was collected through an online questionnaire abd was analized by age range, gender and scientific field. In this paper,gender differences are analyzed and presented in 3 dimensions: type of Internet usage, communication tools and the role of the Internet tools in education.

Abstract
In these days the learning experience is no longer confined within the four walls of a classroom. Computers and primarily the Internet have broadened this horizon by creating a way of delivering education that is known as eLearning. In the meantime, the Internet or, more precisely, the Web is heading towards a new paradigm where the user is no longer just a consumer of information and becomes an active part in the communication. This two-way channel where the user takes the role of the producer of content triggered the appearance of new types of services such as Social Networks, Blogs and Wikis. To seize this second generation of communities and services, educational vendors are willing to develop eLearning systems focused on the new and emergent users needs. This paper describes the analysis and specification of an eLearning environment at our School (ESEIG) towards this new Web generation, called PEACE - Project for ESEIG Academic Environment. This new model relies on the integration of several services controlled by teachers and students such as social networks, repositories, libraries, e-portfolios and e-conference systems, intelligent tutors, recommendation systems, automatic evaluators, virtual classrooms and 3D avatars.

Abstract

Abstract
The linear lambda calculus, where variables are restricted to occur in terms exactly once, has a very weak expressive power: in particular, all functions terminate in linear time. In this paper we consider a simple extension with natural numbers and a restricted iterator: only closed linear functions can be iterated. We show properties of this linear version of Godel's T using a closed reduction strategy, and study the class of functions that can be represented. Surprisingly, this linear calculus offers a huge increase in expressive power over previous linear versions of T, which are 'closed at construction' rather than 'closed at reduction'. We show that a linear T with closed reduction is as powerful as T.

Abstract
System L I is a linear ?-calculus with numbers and an iterator, which, although imposing linearity restrictions on terms, has all the computational power of Gödel's System I. System LI owes its power to two features: the use of a closed reduction strategy (which permits the construction of an iterator on an open function, but only iterates the function after it becomes closed), and the use of a liberal typing rule for iterators based on iterative types. In this paper, we study these new types, and show how they relate to intersection types. We also give a sound and complete type reconstruction algorithm for System LI. © 2010 Springer Science+Business Media, LLC.

Abstract
Technological evolution is leading telecommunications to all-IP networks where multiple services are transported as IP packets. Among these are the group communications services with confidentiality requirements. Secure IP multicast may be used to secure the broadcast of video channels. However, in scenarios such as cable TV where the concept of video channel and bundle are present, groups are very large, and users switch very rapidly between channels (zapping), a sort of problems still need to be addressed. The solution proposed in this paper addresses these problems. For that purpose, a centralized form of secure group communications is proposed also used to transmit, not data, but group cryptographic material. Threes types of cryptographic keys are used. End systems use this material to decrypt the data sent by the content providers.