Programs are more distributed and concurrent today than ever before, and structural communications are at the core. Constructing and debugging such programs are hard due to the lack of formal specifications and verifications of concurrency. Recent advances in type systems allow us to specify the structures of communications as session types, thus enabling static type checking of the usages of communication channels against protocols. The soundness of session type systems implies communication fidelity and absence of deadlock. This work proposes to formalize multiparty dependent session types as an expressive and practical type discipline for enforcing communication protocols. The type system is formulated in the setting of multi-threaded λ-calculus with inspirations from multirole logic. It is sound, and it provides linearity and coherence guarantees entirely statically. The type system supports recursion and polymorphism. The formulation is particularly suitable for practical implementation, and this work provides such a runtime implementation.

Estágio realizado na Novabase e orientado pelo Eng.º Pedro Faúlha / Tese de mestrado integrado. Engenharia Informátca e Computação. Faculdade de Engenharia. Universidade do Porto. 2008

No description available.

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (leaves 103-110). Also available via the World Wide Web.

Thesis (M.S.)--Villanova University, 2007. / Computer Science Dept. Includes bibliographical references.

Thesis (MS)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Brock LaMeres. Includes bibliographical references (leaves 44-47).

Behavior analysts refer to a decrease in response rate following repeated, contingent presentations of a reinforcing stimulus as a product of satiation. Other evidence suggests that these decreases may often be due to habituation to the sensory properties of the reinforcing stimulus. The investigation reported here sought to determine whether decreases in operant responding by 3 adults with developmental disabilities were due to satiation or habituation. During baseline, participants placed poker chips into a container, and no reinforcement was available. Within subsequent phases, participants received diet lemon-lime soda on a fixed-ratio (FR) schedule of reinforcement. In one condition, the color of the soda was constant throughout the session, and in another condition food coloring was added several minutes into the session. Results for at least 2 participants indicated that: (a) soda functioned as a reinforcer for placing poker chips in the can; (b) response rates decreased within the session to baseline levels; and (c) response rates increased following a change in the color of the soda within the session. Results for the third participant were less clear. The results support the argument made by other researchers that the terms habituation (a weakening of a behavior following contact with the reinforcing stimulus) and stimulus specificity (a strengthening of a behavior following a change in the reinforcing stimulus) may be more appropriate descriptors of within-session changes in responding. The factors associated with habituation and satiation, as well as both basic and applied research examples, are discussed.

High data rate wireless packet data networks have made real-time IP based services available through mobile devices. At the same time, differences in the characteristics of radio technologies (802.11/WiFi and 3G networks) make seamless handoff across heterogeneous wireless networks difficult. Despite this, many believe that the ultimate goal of next generation networks (often referred to as the fourth generation) is to allow convergence of such dissimilar heterogeneous networks. Supporting voice over Internet Protocol in next-generation wireless systems is thought by some to require support for mobility and quality of service features. Currently a mobile node can experience interruptions or even sporadic disconnections of an on going real-time session due to handovers between both networks of different types and networks of the same type. Many tests have already been done in this area and one may wonder why it is worth spending even more time investigating it? This thesis focuses on the important problem of providing session security despite handovers between networks (be they operated by the same operator or different operators and be they the same link technologies or different). One of the goals in this thesis is to investigate how an ongoing speech session can continue despite a change in transmission media1. Additionally, a number of security threats that could occur due to the handover will be identified and presented. Finally, the most suitable solution to address these threats will be tested in a real environment. Eventual shortcomings and weaknesses will be identified and presented; along with suggestions for future work.  1 When utilizing IP over carriers such as wired Ethernet, WLAN, and 3G. / Trådlösa hög-hastighets datanät har möjliggjort appliceringen av realtids tjänster på mobil utrustning över IP. Samtidigt har skillnaderna i de olika radioteknologierna (802.11/WiFi och 3G näten) introducerat nya problem med att upprätthålla trådlösa kommunikationen tvärs den heterogena trådlösa accessen. Många tror att slutmålet för nästa generations nätverk (ofta refererade som fjärde generationens nätverk) är att tillåta konvergensen av dessa olika heterogena nätverk. Stödet för Voice over Internet Protokollet (VoIP) i nästa generations trådlösa nät tror somliga kräver ett inslag av kombination mellan mobilitet samt upprätthållandet av kvaliteten. För närvarande kan den mobila noden (MN) råka ut för störningar och även sporadiska avbrott av en pågående realtidssessionen på grund av övergångar mellan samma eller olika typer av medier. Många tester har redan gjorts inom det här området och man kan fråga sig varför det är värt att lägga ner ännu mer tid på att undersöka det här? Det här examensarbetet fokuserar på det viktiga problemet som handlar om att kunna erbjuda sessions säkerhet trots övergångar mellan näten (oavsett om dessa drivs av samma eller olika operatörer samt oavsett om de är av samma eller olika nätverks typ). Ett av målen för det här examensarbetet är att undersöka hur en pågående talsession behålls vid byte av transmissionsmedia2. Vidare kommer olika säkerhetsaspekter och hot som kan tänkas uppstå vid bytet att identifieras och presenteras. Slutligen kommer den mest lämpade lösningen till problemet att testas i verklig miljö. Eventuella brister och svagheter kommer att identifieras och redovisas i slutet av rapporten tillsammans med förslag på framtida arbete. 2 Då man nyttjar IP bärare som trådbundet Ethernet, WLAN och 3G.

The switched telephony network was designed for voice calls. Expansion of datacommunication has lead to a wide range of experimentation to create new services. Theses services take place outside the network. When adding new services we currently encounter problems due to limitations of the simple devices at end points. Theo Kanter has proposed a new model to remove these limitations; this model is called “Adaptive Personal Mobile Communication”. The model consists of several components in the application layer of ISO standard. This model is based on peer to peer connections and the purpose of this model is to move services from within the networks to end point devices and avoid using central servers within the network. The Session Initiation Protocol (SIP) for establishing multimedia sessions allows us to move the point of integration for multimedia service integration out to the end-points. This project concerns the implementing of a prototype of this model as an SIP extension along with it evaluation. SIP offer addressing, naming, and localization of resources in this project. This report presents different design alternatives for XSP as an SIP extension, and the chosen model presents as a result of comparing of these design alternatives.

This master thesis is the documented work of the construction process and testing of a three hour laboratory session in mathematics aimed at high school level students. The purpose of the thesis was to create an interesting laboratory session for the science education center ”The House of Science” that could be used as a part of their regular program directed to schools. The thesis explores the possibilities for how one can construct a laboratory session on the topic ”molecular symmetry” as well as the underlying pedagogical theories used to describe learning processes in creative contexts. A model for such a session is proposed, an evaluation is conducted and its results and implications are appropriately discussed. An important review of the mathematical background of symmetries, group theory and linear representations of finite groups was written and can be found in the appendices.