A arquitetura IP Multimedia Subsystem, proposta pelo consórcio 3rd Generation Partnership Project como base para o suporte à convergência entre telefonia móvel e a Internet, define uma série de elementos arquiteturais, entre os quais, o componente Call Session Control Function e o protocolo Session Initiation Protocol. Session Initiation Protocol é um protocolo da camada de aplicação utilizado para estabelecer, modificar e terminar sessões multimídia entre dispositivos. Em redes baseadas na arquitetura IP Multimedia Subsystem, o Session Initiation Protocol é o responsável pela comunicação entre dispositivos e a rede, e entre os componentes responsáveis pelo gerenciamento de sessão. Nos últimos anos, estudos detectaram degradação de desempenho em redes baseadas na arquitetura IP Multimedia Subsystem em função das características centralizadas do Session Initiation Protocol e dos componentes de gerenciamento de sessão. Este trabalho apresenta uma arquitetura distribuída para redes baseadas em IP Multimedia Subsystem, tendo como fundamento o paradigma de computação paralela baseado em espaço de tuplas onde os servidores são organizados em uma rede P2P, com objetivo de prover uma infraestrutura escalável e tolerante a falhas. A validação da arquitetura em termos de desempenho e escalabilidade se deu através de modelagem formal e simulação com Redes de Petri Coloridas. / The IP Multimedia Subsystem architecture, proposed by the 3rd Generation Partnership Project consortium as basis to support the convergence between mobile networks and the Internet, defines a set of architectural elements, among them, the Call Session Control Function and the Session Initiation Protocol. The Session Initiation Protocol is an application layer protocol used to establish, modify and terminate sessions between devices. On the IP multimedia subsystem based network, the Session Initiation Protocol play a key role on the communication between devices and the network, and between session management components. In the last years, studies have detected a performance bottleneck on IP multimedia subsystem networks due to centralized characteristic of the Session Initiation Protocol and in Session Control components. This work shows a distributed architecture for IP Multimedia Subsystem networks based on the tuple space paradigm, and the servers structured in a P2P network, aiming to achieve a scalable and fault-tolerant infrastructure. The validation of the architecture on the performance and scalability took place through the Coloured Petri Net formal modeling and simulation.

O uso de técnicas e métodos formais contribui para o desenvolvimento de sistemas confiáveis. No entanto, apesar do rigor obtido, em geral, é necessário que essas técnicas sejam complementadas com atividades de teste e validação. Deve-se ressaltar que o custo para eliminar erros encontrados nas etapas iniciais de desenvolvimento é menor do que quando esses erros são encontrados nas fases posteriores. Dessa forma, é essencial a condução de atividades de VV&T - Verificação, Validação e Teste - desde as primeiras fases de desenvolvimento. Critérios de teste, como uma forma sistemática de avaliar e/ou gerar casos de teste de qualidade e, dessa forma, contribuir para aumentar a qualidade da atividade de teste, têm sido investigados para o teste de especificação de Sistemas Reativos. A técnica Redes de Petri Coloridas tem sido constantemente utilizada para a especificação do aspecto comportamental de Sistemas Reativos. Apesar de existirem diversas técnicas de análise, um aspecto não considerado é a cobertura alcançada, visto que, em geral, a aplicação exaustiva não é viável devido ao alto custo. Considerando a relevância do estabelecimento de métodos sistemáticos para o teste e validação dessas especificações, este trabalho propõe a aplicação do critério de teste Análise de Mutantes para o teste de Redes de Petri Coloridas. Neste trabalho foram almejados três objetivos principais, os quais podem ser divididos em estudos teóricos, estudos empíricos e automatização. No contexto de estudos teóricos, foi realizada a definição e embasamento teórico para possibilitar a aplicação da Análise de Mutantes no contexto de Redes de Petri Coloridas. Além disso, investigaram-se mecanismos genéricos para a descrição e geração de mutantes. Definiu-se um algoritmo para a geração de casos de teste baseado na Análise de Mutantes. No contexto de estudos empíricos, foram conduzidos estudos de caso para avaliar a aplicabilidade e eficácia dos resultados teóricos obtidos. Finalmente, no contexto de automatização, foram desenvolvidas ferramentas de apoio à aplicação da Análise de Mutantes. / The usage of formal methods and techniques contributes to the development of highly reliable system, but, in spite of the achieved rigour, these techniques must be complemented with testing and validation activities. It should be highlighted that the cost to eliminate errors found in the early phases of development is smaller than when those errors are found in the later phases. Therefore, the accomplishment of VV&T activities - Verification, Validation and Test - starting at the first development phases is essential. Testing criteria, as a systematic way to evaluate and/or generate test cases, contributing, therefore, to improve the quality of the test activity, have been proposed for testing reactive systems specifications. A technique that has been steadily employed for specifying the behavioural aspect of reactive systems is the coloured Petri nets. Although there are several analysis and validation techniques, a usually neglected aspect is the achieved coverage, given that, in general, the exhaustive application is not feasible due to its high cost. Considering the relevance of establishing systematic methods for the test and validation of coloured Petri nets based specification, this work proposes the investigation of the viability of applying Mutation Testing to test coloured Petri nets. In this work three main goals were pursued, which can be grouped in: theoretical studies, empirical studies and tool development. In the context of theoretical studies, it was accomplished the definition of theoretical concepts to enable the application of Mutant Analysis in the context of coloured Petri nets. Moreover, a mutation-based algorithm was defined to generate test sequences for Petri nets. In the context of empirical studies, case studies were carried out to evaluate the applicability and effectiveness of the achieved theoretical results. Finally, in the context of tool development, tools for supporting the application of Mutation Testing were developed.

Coloured final states are ubiquitous at hadron colliders such as the Large Hadron Collider (LHC). Therefore understanding high energy perturbative quantum chromodynamics (QCD) at these experiments is essential not only as a test of the Standard Model, but also because these processes form the dominant background to many searches for new physics. One such `standard candle' is the production of a dilepton pair in association with dijets. Here we present a new description of this final state (through the production of a Z⁰ boson and γ*). This calculation adds to the fixed-order accuracy the dominant logarithms in the limit of large partonic centre-of-mass energy to all orders in the strong coupling αs. This is achieved within the framework of High Energy Jets. This calculation is made possible by extending the high energy treatment to take into account the multiple t-channel exchanges arising from Z⁰ and gamma* -emissions off several quark lines. The correct description of the interference effects from the various t-channel exchanges requires an extension of the subtraction terms in the all-order calculation. We describe this construction and compare the resulting predictions to a number of recent analyses of LHC data. The description of a wide range of observables is good, and, as expected, stands out from other approaches in particular in the regions of large dijet invariant mass and large dijet rapidity spans. In addition we also present the application of the High Energy Jets framework to two new experimental scenarios. Firstly, we show a comparison of High Energy Jets matched to the ARIADNE parton shower to an ATLAS study of gap activity in dijet events. We see that our description agrees well with the data throughout and in many distributions gives the best theoretical description. This shows the extra logarithmic corrections are essential to describe data already in LHC Run I. Secondly, we present a study of Z⁰/γ* plus dijets at 100 TeV. We compare the behaviour of the high energy logarithmic enhancements to the QCD perturbative series at 7 TeV and 100 Tev and see that at any high energy hadronic Future Circular Collider (FCC) the effects described by our resummation become significantly more important.

The Atlantic salmon (Salmo salar) lifecycle is punctuated by distinct ontogenic stages which are routinely manipulated commercially by photoperiod regimes to enable year-round production. As such, light plays a critical role throughout the production cycle, however, it remains poorly characterised and light spectrum and intensity have not been defined optimally yet. This thesis was therefore set out to test the effects of narrow bandwidth light (Blue-λ(max) 444 nm, Green-λ(max) 523 nm, Red-λ(max) 632 nm and White) and intensity in freshwater (FW). Fry-parr development, out-of-season smoltification and ocular and vertebral health were examined as was the long-term effects of FW light regimes on seawater (SW) growth and muscle structure. In addition, the impact of photoperiod regimes on out-of-season smolts following transfer to SW was investigated. 
 Major findings from the trials conducted show that light spectrum and intensity influence parr development with lower intensities performing better than higher intensities. Both the initiation and duration of smoltification was impacted by spectrum. Importantly, this doctoral work showed that daily changes in light intensity, from low during the scotophase to high during the photophase applied for the duration of a standard out-of-season smoltification regime was capable of providing a sufficient cue for the induction of smoltification. Historic FW light exposure impacted SW performance and post-transfer SW photoperiod had significant impact upon growth and maturation development. Results based on changes to the gonadosomatic index provide important guidance for suitable post-transfer photoperiods for smolt transferred to SW around the winter solstice. Importantly, from the parameters tested, exposure to different spectrum or light intensities did not adversely affect vertebral or ocular health. 
 This thesis did not only focus on the physiological effects of light but also aimed to characterise better the pathways involved in light perception and integration. To do so, the neural response to both broad spectrum white light, darkness and Red and Blue light was investigated through deep brain insitu-hybridisation and high throughput sequencing (NGS) of the pituitary gland. Results showed substantial spectral and light/dark changes in the both the deep brain and pituitary transcriptome. Overall, this research provides both scientifically interesting and commercially relevant guidance for the optimisation of lighting systems for use in captive salmon aquaculture. Major findings from the trials conducted show that light spectrum and intensity influence parr development with lower intensities performing better than higher intensities. Both the initiation and duration of smoltification was impacted by spectrum. Importantly, this doctoral work showed that daily changes in light intensity, from low during the scotophase to high during the photophase applied for the duration of a standard out-of-season smoltification regime was capable of providing a sufficient cue for the induction of smoltification. Historic FW light exposure impacted SW performance and post-transfer SW photoperiod had significant impact upon growth and maturation development. Results based on changes to the gonadosomatic index provide important guidance for suitable post-transfer photoperiods for smolt transferred to SW around the winter solstice. Importantly, from the parameters tested, exposure to different spectrum or light intensities did not adversely affect vertebral or ocular health. This thesis did not only focus on the physiological effects of light but also aimed to characterise better the pathways involved in light perception and integration. To do so, the neural response to both broad spectrum white light, darkness and Red and Blue light was investigated through deep brain insitu-hybridisation and high throughput sequencing (NGS) of the pituitary gland. Results showed substantial spectral and light/ dark changes in the both the deep brain and pituitary transcriptome. Overall, this research provides both scientifically interesting and commercially relevant guidance for the optimisation of lighting systems for use in captive salmon aquaculture.

A arquitetura IP Multimedia Subsystem, proposta pelo consórcio 3rd Generation Partnership Project como base para o suporte à convergência entre telefonia móvel e a Internet, define uma série de elementos arquiteturais, entre os quais, o componente Call Session Control Function e o protocolo Session Initiation Protocol. Session Initiation Protocol é um protocolo da camada de aplicação utilizado para estabelecer, modificar e terminar sessões multimídia entre dispositivos. Em redes baseadas na arquitetura IP Multimedia Subsystem, o Session Initiation Protocol é o responsável pela comunicação entre dispositivos e a rede, e entre os componentes responsáveis pelo gerenciamento de sessão. Nos últimos anos, estudos detectaram degradação de desempenho em redes baseadas na arquitetura IP Multimedia Subsystem em função das características centralizadas do Session Initiation Protocol e dos componentes de gerenciamento de sessão. Este trabalho apresenta uma arquitetura distribuída para redes baseadas em IP Multimedia Subsystem, tendo como fundamento o paradigma de computação paralela baseado em espaço de tuplas onde os servidores são organizados em uma rede P2P, com objetivo de prover uma infraestrutura escalável e tolerante a falhas. A validação da arquitetura em termos de desempenho e escalabilidade se deu através de modelagem formal e simulação com Redes de Petri Coloridas. / The IP Multimedia Subsystem architecture, proposed by the 3rd Generation Partnership Project consortium as basis to support the convergence between mobile networks and the Internet, defines a set of architectural elements, among them, the Call Session Control Function and the Session Initiation Protocol. The Session Initiation Protocol is an application layer protocol used to establish, modify and terminate sessions between devices. On the IP multimedia subsystem based network, the Session Initiation Protocol play a key role on the communication between devices and the network, and between session management components. In the last years, studies have detected a performance bottleneck on IP multimedia subsystem networks due to centralized characteristic of the Session Initiation Protocol and in Session Control components. This work shows a distributed architecture for IP Multimedia Subsystem networks based on the tuple space paradigm, and the servers structured in a P2P network, aiming to achieve a scalable and fault-tolerant infrastructure. The validation of the architecture on the performance and scalability took place through the Coloured Petri Net formal modeling and simulation.

Increasing focus is being placed on fair assessment practices in South Africa. Most psychological tests used in this country were designed and developed in other countries. Research has shown that when using these tests on a different target population, it is important to determine the suitability of the test for that population. This involves investigating reliability, validity and possible sources of bias. It is equally important to have local normative data with which scores can be compared and interpreted. Research in this area has been limited. The purpose of this study was to undertake such research by evaluating a widely used test, the Raven's Coloured Progressive Matrices (RCPM), and its existing norms, for Zulu children in South Africa. The study also aimed to provide raw data, which could be used to assist with the compilation of local norms. The test was administered to a convenience sample of 522 primary school children between the ages of 5 and 12 years old. The sample was divided into two groups to represent two different geographical locations: rural and urban. The sample consisted of 284 rural children and 237 urban children. There were 263 males and 259 females in the sample. Findings indicated good test reliability for this sample. Test validity however could not be confirmed as possible sources of bias at the content and item levels were shown. Age had a significant effect on performance, but level of education appeared to be the strongest predictor of performance on the RCPM for this sample. Significant gender differences were found. There was a tendency for males to outperform females on the test. Location had a significant effect on scores, where urban children performed better than rural children. Comparison of Zulu sample scores with those produced by the British standardisation sample, revealed a large discrepancy in performance between the two different cultural groups. The Zulu sample mean scores were significantly lower than the British mean scores. These findings highlight the need for locally developed normative data. The validity of the test for the sample requires further investigation. Results indicate that test adaptation may be required for Zulu children. / Thesis (M.A.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

No abstract available. / Thesis (M.A.)-University of Natal, Durban, 1974.

This study aims to explore how young coloured girls, aged 16-17, give meaning to sexuality. Coloured girls’ are often marginalised in South African research and debate around gender and sexuality. This study focuses on coloured girls in two different social and economic contexts in Durban. The one context is Wentworth which remains a predominantly coloured working class area. The other is a middle class former white area in Glenwood Durban. The study draws on qualitative research using interview methods to focus on eight girls in these two areas. Three of the girls emerged from Glenwood whilst five others live in Wentworth. The aim of the study was to understand the ways in which class impacted on their meanings of sexuality. Gender, race and class are intertwined social constructs which assist in the formulation of sexual identities. This study investigated the similarities and differences between the two groups of coloured girls. They differed in relation to: their mindsets regarding everyday life, for example the girls from Glenwood interacted with boys from all four racial groups and had a better understanding of their different cultures. The girls from Wentworth found boys from racial groups other than coloured more attractive due to lack of knowledge of them. Thus the girls from Glenwood were open to multi-racial relationships whilst the girls from Wentworth were afraid to do so, as they would be subject to ridicule from the community. In Wentworth ones status is defined by clothing, cash and cars and in order for these young girls to be successful in this community they must affiliate themselves with boys/men who can provide such things; even if they come at a high price. In this study the girls were similar in that they all wanted to be independent, wanted to finish school, find good jobs, and buy their own cars, thus we see the feminine agency of coloured girls from two different socio-economic contexts. / Thesis (M.Ed.)-University of KwaZulu-Natal, Edgewood, 2011.

Over the past decade, the ubiquity of business processes and their need for ongoing management in the same manner as other corporate assets has been recognized through the establishment of a dedicated research area: Business Process Management (or BPM). There are a wide range of potential software technologies on which a BPM o®ering can be founded. Although there is signi¯cant variation between these alternatives, they all share one common factor { their execution occurs on the basis of a business process model { and consequently, this ¯eld of technologies can be termed Process-Aware Information Systems (or PAIS). This thesis develops a conceptual foundation for PAIS based on the results of a detailed examination of contemporary o®erings including work°ow and case han- dling systems, business process modelling languages and web service composition languages. This foundation is based on 126 patterns that identify recurrent core constructs in the control-°ow, data and resource perspectives of PAIS. These patterns have been used to evaluate some of the leading systems and business process modelling languages. It also proposes a generic graphical language for de¯ning exception handling strategies that span these perspectives. On the basis of these insights, a comprehensive reference language { newYAWL { is developed for business process modelling and enactment. This language is formally de¯ned and an abstract syntax and operational semantics are provided for it. An assessment of its capabilities is provided through a comprehensive patterns-based analysis which allows direct comparison of its functionality with other PAIS. newYAWL serves as a reference language and many of the ideas embodied within it are also applicable to existing languages and systems. The ultimate goal of both the patterns and newYAWL is to improve the support and applicability of PAIS.

Denial-of-service attacks (DoS) and distributed denial-of-service attacks (DDoS) attempt to temporarily disrupt users or computer resources to cause service un- availability to legitimate users in the internetworking system. The most common type of DoS attack occurs when adversaries °ood a large amount of bogus data to interfere or disrupt the service on the server. The attack can be either a single-source attack, which originates at only one host, or a multi-source attack, in which multiple hosts coordinate to °ood a large number of packets to the server. Cryptographic mechanisms in authentication schemes are an example ap- proach to help the server to validate malicious tra±c. Since authentication in key establishment protocols requires the veri¯er to spend some resources before successfully detecting the bogus messages, adversaries might be able to exploit this °aw to mount an attack to overwhelm the server resources. The attacker is able to perform this kind of attack because many key establishment protocols incorporate strong authentication at the beginning phase before they can iden- tify the attacks. This is an example of DoS threats in most key establishment protocols because they have been implemented to support con¯dentiality and data integrity, but do not carefully consider other security objectives, such as availability. The main objective of this research is to design denial-of-service resistant mechanisms in key establishment protocols. In particular, we focus on the design of cryptographic protocols related to key establishment protocols that implement client puzzles to protect the server against resource exhaustion attacks. Another objective is to extend formal analysis techniques to include DoS- resistance. Basically, the formal analysis approach is used not only to analyse and verify the security of a cryptographic scheme carefully but also to help in the design stage of new protocols with a high level of security guarantee. In this research, we focus on an analysis technique of Meadows' cost-based framework, and we implement DoS-resistant model using Coloured Petri Nets. Meadows' cost-based framework is directly proposed to assess denial-of-service vulnerabil- ities in the cryptographic protocols using mathematical proof, while Coloured Petri Nets is used to model and verify the communication protocols using inter- active simulations. In addition, Coloured Petri Nets are able to help the protocol designer to clarify and reduce some inconsistency of the protocol speci¯cation. Therefore, the second objective of this research is to explore vulnerabilities in existing DoS-resistant protocols, as well as extend a formal analysis approach to our new framework for improving DoS-resistance and evaluating the performance of the new proposed mechanism. In summary, the speci¯c outcomes of this research include following results; 1. A taxonomy of denial-of-service resistant strategies and techniques used in key establishment protocols; 2. A critical analysis of existing DoS-resistant key exchange and key estab- lishment protocols; 3. An implementation of Meadows's cost-based framework using Coloured Petri Nets for modelling and evaluating DoS-resistant protocols; and 4. A development of new e±cient and practical DoS-resistant mechanisms to improve the resistance to denial-of-service attacks in key establishment protocols.