Petri nets are named in honor of Dr. Carl A. Petri for his famous Ph.D dissertation of general net theory in 1962. A substantial amount of work utilizing and modifying the Petri nets has been done since then, and they have turned out to be very useful in the study of asynchronous concurrent systems. The liveness and reachability problems are considered to be some of the major problems in Petri net theory.Since the structure of a Petri net can be regarded as sets of places and transitions form a graphical point of view, this thesis is concerned with utilizing the results of graph theory to investigate the liveness in terms of deadlock problems of a special subclass of Petri nets, free-choice Petri nets. As a subclass of Petri nets, the class of free-choice Petri nets possesse relatively strong analysis properties. This is especially true of complete free-choice Petri nets. We show in particular that any system which can be modeled by a general Petri net can also be modeled by a free-choice Petri net. / Department of Computer Science

Bibliography: leaves 177-191. This thesis uses a new type of extended time Petri net to model and analyse command and control decision processes. A comprehensive review of existing time Petri net structures is given. This concludes with the introduction of time Petri net structure that incorporates the most commonly used time structures. This extended time Petri net structure is then used in the definition of the basic modelling blocks required to model command and control decision processes. This basic modelling block forms the basis of the direct analysis techniques that are introduced in the thesis.

Effective command and control is crucial to both military and non-military environments. Accurate representations of the processes associated with the inter and intra activities of nodes or agencies of such systems is essential in the analysis of command and control. One of the most important things is to be able to model the decision processes. These are the parts of the system that make decisions and then guide the direction of other elements in the system overall. This thesis uses a new type of extended time Petri net to model and analyse command and control decision processes. A comprehensive review of existing time Petri net structures is given. This concludes with the introduction of a time Petri net structure that incorporates the most commonly used time structures. This extended time Petri net structure is then used in the definition of the basic modelling blocks required to model command and control decision processes. This basic modelling block forms the basis of the direct analysis techniques that are introduced in the thesis. Due to the transient nature of the systems being modelled and the measures of interest a new type of measure is introduced, the mean conditional first hitting reward. This measure does not currently appear to be part of the stochastic process literature. Explicit procedures are given to determine the hitting probabilities and mean conditional first hitting reward for decision process models and discrete, continuous and semi-Markov chains. Finally the some extensions of the decision process sub-class are considered. / Thesis (Ph.D.) - University of Adelaide, Dept. of Applied Mathematics, 2001

Bibliography: leaves 145-156 / viii, 156 leaves ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 1992

Thesis (Ph. D.)--University of Adelaide, Dept. of Applied Mathematics, 1992. / Includes bibliographical references (leaves 145-156).

Thesis (Ph.D)-- University of Adelaide, Dept. of Applied Mathematics, 2001. / Bibliography: leaves 177-191.

[No abstract available] / Science, Faculty of / Chemistry, Department of / Graduate

La mucoviscidose est une maladie génétique caractérisée par une inflammation pulmonairepersistante du poumon résultant d’un recrutement massif de polynucléaires neutrophiles quisécrètent trois protéases à sérine, l’élastase leucocytaire, la protéase 3 et la cathepsine G. Ledéséquilibre de la balance protéases/antiprotéases au site inflammatoire contribue à la protéolyse dutissu pulmonaire et provoque à terme l’insuffisance respiratoire des patients. Les stratégiesthérapeutiques utilisant des inhibiteurs endogènes n’ont pas abouti aux résultats espérés et n’ontciblé que l’élastase soluble. Nous avons étudié l’activité et la régulation des protéases duneutrophile dans les expectorations des patients atteints de mucoviscidose Nous avons démontrél’importance des pièges neutrophiliques extracellulaires (NETs) dans leur séquestration, ce quiexplique leur résistance à l’inhibition et en conséquence leur pouvoir de destruction du tissupulmonaire. Nous avons également démontré qu’un traitement par la DNase facilite l’action desinhibiteurs ce qui ouvre de nouvelles stratégies de thérapie anti-inflammatoire. / No summary available

O Chikungunya é um vírus reemergente que causa uma doença caracterizada por uma artralgia incapacitante que afeta milhares de pessoas. A resposta inata contra este vírus é bem descrita pela participação de macrófagos, células dendríticas e células NK, porém há poucos trabalhos que demonstram o papel dos neutrófilos nesta infecção. As Neutrophil Extracellular Traps (NETs) constituem uma rede de DNA complexada a enzimas antimicrobianas que foram descritas por combaterem diversos patógenos. Porém, não há trabalhos que demonstram sua importância em infecção por Chikungunya. Nosso objetivo foi investigar se há produção de NETs na infecção por Chikungunya, descrever seus mecanismos e demonstrar sua importância in vitro e in vivo. Observamos que neutrófilos murinos e humanos incubados com Chikungunya são capazes de produzir NETs via Toll-Like 7 e produção de espécies reativas de oxigênio. Estas NETs foram capazes de capturar o vírus e impedir sua infecção in vitro. Mais além, animais infectados com Chikungunya e tratados com rhDNAse apresentam maior carga viral e são mais suscetíveis à infecção, demonstrando sua importância in vivo. Por fim, pacientes diagnosticados em fase aguda de infecção por Chikungunya possuem elevados níveis de NETs correlacionados com uma alta carga viral. / Chikungunya is a reemerging virus which causes a disease characterized by an incapacitanting arthralgia and affects thousands of people. Innate response against this virus is well described by participation of macrophages, dendritic cells and NK cells, however few works demonstrate the roe of neutrophils in this infection. Neutrophils Extracellular Traps are a web of DNA complexed with antimicrobial enzymes which were described for fighting against many pathogens. However, there are no works which demonstrate its relevance in Chikungunya infection. Our objective was to evaluate if there is release of NETs in Chikungunya infection, describe its mechanisms and demonstrate its relevance in vitro and in vivo. We observed that mouse and human neutrophils incubated with Chikungunya are able to produce NETs via Toll-Like 7 and reactive oxygen species production. These NETs were able to capture the virus and inhibit its infection in vitro. Moreover, animals infected with Chikungunya virus and treated with rhDNAse demonstrated higher viral load and are more susceptible to the infection, showing its importance in vivo. Lastly, patients diagnosed during acute infection of Chikungunya infection have high levels of NETs correlated with a high viral load.

O Chikungunya é um vírus reemergente que causa uma doença caracterizada por uma artralgia incapacitante que afeta milhares de pessoas. A resposta inata contra este vírus é bem descrita pela participação de macrófagos, células dendríticas e células NK, porém há poucos trabalhos que demonstram o papel dos neutrófilos nesta infecção. As Neutrophil Extracellular Traps (NETs) constituem uma rede de DNA complexada a enzimas antimicrobianas que foram descritas por combaterem diversos patógenos. Porém, não há trabalhos que demonstram sua importância em infecção por Chikungunya. Nosso objetivo foi investigar se há produção de NETs na infecção por Chikungunya, descrever seus mecanismos e demonstrar sua importância in vitro e in vivo. Observamos que neutrófilos murinos e humanos incubados com Chikungunya são capazes de produzir NETs via Toll-Like 7 e produção de espécies reativas de oxigênio. Estas NETs foram capazes de capturar o vírus e impedir sua infecção in vitro. Mais além, animais infectados com Chikungunya e tratados com rhDNAse apresentam maior carga viral e são mais suscetíveis à infecção, demonstrando sua importância in vivo. Por fim, pacientes diagnosticados em fase aguda de infecção por Chikungunya possuem elevados níveis de NETs correlacionados com uma alta carga viral. / Chikungunya is a reemerging virus which causes a disease characterized by an incapacitanting arthralgia and affects thousands of people. Innate response against this virus is well described by participation of macrophages, dendritic cells and NK cells, however few works demonstrate the roe of neutrophils in this infection. Neutrophils Extracellular Traps are a web of DNA complexed with antimicrobial enzymes which were described for fighting against many pathogens. However, there are no works which demonstrate its relevance in Chikungunya infection. Our objective was to evaluate if there is release of NETs in Chikungunya infection, describe its mechanisms and demonstrate its relevance in vitro and in vivo. We observed that mouse and human neutrophils incubated with Chikungunya are able to produce NETs via Toll-Like 7 and reactive oxygen species production. These NETs were able to capture the virus and inhibit its infection in vitro. Moreover, animals infected with Chikungunya virus and treated with rhDNAse demonstrated higher viral load and are more susceptible to the infection, showing its importance in vivo. Lastly, patients diagnosed during acute infection of Chikungunya infection have high levels of NETs correlated with a high viral load.