Abstract
We show that the full PCF language can be encoded in L-rec, a syntactically linear lambda-calculus extended with numbers, pairs, and an unbounded recursor that preserves the syntactic linearity of the calculus. We give call-by-name and call-by-value evaluation strategies and discuss implementation techniques for L-rec, exploiting its linearity.

Abstract
This chapter proposes a novel concept towards the deployment of a networked 'Media Ecosystem'. The proposed solution is based on a flexible cooperation between providers, operators, and end-users, finally enabling every user first to access the offered multimedia services in various contexts, and second to share and deliver his own audiovisual content dynamically, seamlessly, and transparently to other users. Towards this goal, the proposed concept provides content-awareness to the network environment, network- and user context-awareness to the service environment, and adapted services/content to the end user for his best service experience possible, taking the role of a consumer and/or producer. © 2011 Springer-Verlag Berlin Heidelberg.

Abstract
With the ongoing increase of the network technologies' diversity and the integration of the user level applications, the legacy-style content-independent configuration of the security mechanisms cannot yields in efficient security solutions farther. Our work aims to contribute on the design of auto-reconfigurable (adaptive) security services that are capable to satisfy the application's security level required with minimal network resources' usage. In this paper we propose a new networkcentric security architecture design that relies on the current network security conditions and content-aware mechanisms. The architecture main functional blocks and the corresponding relationships are defined. This architecture shall supply three inter-domain composite user security services, named "public traffic", "secret content" and "private communication", as well as, attack source traceback and distributed access control functionalities.

Abstract
IPTV services consist of multiple video channels grouped in bundles, such as sports, movies or generic bundles; users typically subscribe multiple bundles, including the generic bundle. Secure IP multicast can be used to implement IPTV services, but it still has problems to be addressed. Current solutions require high computational power in video channel zapping situations, lack support for groups sourced at the users, and present a weak support for admission control in IP multicast for both sources and receivers in dynamically configured environments. This work proposes a new, secure and efficient IPTV solution that, cumulatively: (a) enforces individual access control to groups of real-time IPTV video channels; (b) enforces IP multicast admission control for both multicast senders and receivers; (c) supports user generated videos; (d) generates low signaling overheads; (e) does not introduce perceivable delays, particularly in video channel zapping situations. Moreover, this solution can be easily integrated in the IPTV architectures being developed by ETSI and ITU-T.

Abstract
Users increasingly own, and use, multiple computing devices. To be able to access their personal data, at any time and in any device, users usually need to create replicas in each device. Managing these multiple replicas becomes an important issue. In this paper we present the FEW Phone File System, a data management system that combines mobile and cloud storage for providing ubiquitous data access. To this end, our system takes advantage of the characteristics of mobile phones for storing a replica of a user's personal data, thus allowing these devices to be used as personal and portable file servers. As users tend to always carry their mobile phone with them at all times, these replicas are the basis for providing high data availability, and keeping replicas automatically synchronized. Our system also uses other replicas located in web servers and cloud storage systems, to reduce the volume of data stored, and transferred to/from mobile phones, by maintaining only the information needed to obtain them.

Abstract
Signal interference and packet collisions are typically viewed as negative factors that hinder wireless communication networks. When security is the primary concern, signal interference may actually be very helpful. Starting with a stochastic network model, we are able to show that packet collisions caused by jamming nodes can indeed be used effectively to attain new levels of secrecy in multiterminal wireless environments. To this effect, we propose a practical jamming protocol that uses the well-known request-to-send/clear-to-send (RTS/CTS) handshake of the IEEE 802.11 standard as a signaling scheme. Various jammer selection strategies are investigated depending on the position of source, destination, and jamming nodes. The goal is to cause asmuch interference as possible to eavesdroppers that are located in unknown positions, while limiting the interference observed by the legitimate receiver. To evaluate the performance of each strategy, we introduce and compute a measure for the secure throughput. Our results show that jamming can increase the levels of secrecy significantly albeit at a substantial cost in terms of energy efficiency.