Despite the growing importance of both destination image and event tourism, a research gap exists when the two fields are combined. Destination image and event tourism have been subject to separate research efforts in the tourism field, however there has been little evidence of research in how events can affect destination image. The thesis attempts to address the research gap that currently exists by using Canberra, the National Capital of Australia and two annual events in the Capital - Stegbar Canberra 400 and Floriade 2002 as case studies. The thesis illustrates the importance of destination image in regard to the destination selection process, the meaning and measurement of image and the growing interest in event tourism. Several studies have illustrated that destination images do influence tourists' behaviour and subsequently decision making (Hunt 1975). Image, among other variables can be the deciding factor in choosing one destination over another. In spite of the importance of this research line, several authors recognise a lack of an agreed way of conceptualising destination image. A conceptual framework of destination image was developed by Echtner and Ritchie (1991) which forms the foundation of the thesis. Although the framework has its flaws, it has been pointed out that the Echtner and Ritchie Destination Image Framework has been useful in the assessment of destination images. Importantly, how events can be used to influence the image of a destination is put forward. Canberra and its image, being the focus of the study, is discussed in detail with reference also to Tamworth and Sydney. Although much of the research into event tourism has focused on the economic benefits that events can provide to a destination, the effect an event can have on the destination image has not been well demonstrated. Research on Canberra has indicated various studies in regard to the perceptions Australians have of the destination, community attitudes towards Canberra and event related research, however the effect that events have on Canberra's image has not been addressed. The thesis incorporates studies of events to measure the effect that they have on the image of a destination. The two main studies were conducted in conjunction with the Centre of Tourism Research (CTR) at the University of Canberra. Two events, held annually in the National Capital, were the focus of the research - Stegbar Canberra 400 and Floriade 2002. Event attendees at the two events were the target sample consisting of both locals and interstate visitors to Canberra. Two key questions related to destination image were added to the existing questionnaires and were the focus of the research. Primary research commenced in June 2002 and concluded November 2002. Destination image responses were derived from both the Stegbar Canberra 400 and Floriade 2002. Results indicated that event attendees regard the two events as being very positive in respect to the destination image of Canberra. The Top 15 responses from both studies also indicate a positive correlation between events and the destination image of Canberra. The Top 15 image responses from the events indicated that events do have an influence on the image of the destination with many event related characteristics appearing in the Top 15 image responses. This was further emphasised when the results from the two events were compared to that of 'Australians' Perceptions of their National Capital' (Richards 2002). General destination images in all three studies were mentioned however Stegbar Canberra 400 and Floriade 2002 image responses were more events driven. The Perceptions study illustrated more unique characteristics of the National Capital along with National attractions. Further, the image results derived from Stegbar Canberra 400 and Floriade illustrates the notion of 'multiple' images that a destination may possess. It is postulated that events have a Life Cycle, and that their influence on destination image varies according to their life cycle stage. It was found that events that lay in the introduction stage of the life cycle have more varied image results that are directly related to the event itself. On the other hand, events that reside in the maturity stage possess strong images related more to the destination itself as opposed to the event. These 'older' events become synonymous with the destination and therefore images are associated with the destination. In conclusion, the research has illustrated that events do have an impact on the image or images of a destination. In this case, the image of Canberra was subject to influence from both Stegbar Canberra 400 and Floriade 2002 event attendees.

Les plantes actinorhiziennes appartiennent à 8 familles d'angiosperme et forment une symbiose fixatrice d'azote avec l'actinomycète du sol Frankia qui aboutit à la formation de nodules au niveau du système racinaire de la plante. Le nodule actinorhizien est considéré comme une racine latérale modifiée car i) il provient de divisions des cellules du péricycle situées en face du pôle de xylème, ii) il possède un méristème apical et un système vasculaire central et iii) chez certaines espèces comme Casuarina glauca une racine nodulaire est produite à l'apex de chaque lobe nodulaire. L'auxine, et notamment le transport d'influx, est impliquée dans la mise en place de la racine latérale. Nous avons donc identifié des gènes de transporteurs d'influx d'auxine chez la plante actinorhizienne C. glauca et étudié le rôle du transport d'influx au cours de la mise en place du nodule actinorhizien.<br />Deux gènes de la famille AUX-LAX codant des transporteurs d'influx d'auxine ont été identifiés C. glauca. Les profils d'expression des gènes CgAUX1 et CgLAX3 sont très conservés entre C. glauca et Arabidopsis thaliana. De plus, des analyses fonctionnelles par complémentation de mutants d'A. thaliana ont mis en évidence une équivalence entre CgAUX1 et AtAUX1. Nos études suggèrent également qu'il existe une divergence fonctionnelle au sein de la famille AUX-LAX.<br />Nous avons analysé le rôle de ces gènes au cours de la mise en place de la symbiose. Notre étude montre que le gène CgAUX1 est exprimé dans les cellules infectées tout au long de l'infection. De plus, le rôle du transport d'influx d'auxine dans le mécanisme d'infection a été confirmé par l'utilisation d'un inhibiteur du transport d'influx. Par ailleurs, le gène CgAUX1 est exprimé dans le primordium de racine latérale mais pas dans le primordium nodulaire. Cela suggère que ces deux organes présentent des différences dans leur programme de développement.<br />Afin d'identifier les mécanismes agissant en aval du transport d'influx d'auxine, nous avons étudié le rôle d'AtLAX3 chez Arabidopsis. Nous avons montré qu'un certain nombre de gènes de remodelage de la paroi sont induits par l'auxine de façon dépendante d'AtLAX3 au cours de l'émergence de la racine latérale. Nous avons cherché à identifier des gènes de remodelage de la paroi qui pourraient être impliqués dans l'infection par la bactérie Frankia de façon dépendante de CgAUX1. Cg12 qui code une protéase de type subtilisine spécifiquement exprimée dans les cellules infectées pourrait être une cible de la signalisation auxinique dépendante de CgAUX1.<br />Nos résultats suggèrent que le transport d'influx d'auxine est impliqué dans la mise en place du nodule actinorhizien chez C. glauca.

Le système de FitzHugh-Nagumo stochastique est un modèle qualitatif pour la propagation de l'influx nerveux dans un neurone. Ce système lent-rapide s'écrit εdxt = (xt - xt3 + yt) dt + √εσ1 dWt(1), dyt = (a - bxt - cyt) dt + σ2 dwt(2) où a, b et c sont des réels, ε est un petit réel positif, σ1 et σ2 sont deux réels positifs représentant l'intensité du bruit, Wt(1) et Wt(2) sont deux mouvements browniens standards indépendants. Dans cette thèse, nous étudions d'abord le système déterministe associé (σ1 = σ2 = 0) et montrons qu'il est excitable. Nous regardons ensuite le cas particulier où b = 0. Dans ce cas, le comportement au voisinage du point d'équilibre est le même que celui d'un autre modèle, celui de Morris-Lecar. Nous étudions alors la loi du temps de sortie de ce voisinage. Dans le cas général, après avoir mis en évidence trois principaux régimes, nous montrons des résultats généraux sur la distribution du nombre de petites oscillations N entre deux spikes consécutifs en introduisant une chaîne de Markov. Puis nous étudions le cas particulier du régime de bruit faible.

We present the first characterization of K+ optimization of N uptake and metabolism in an NH4+-tolerant species, tropical lowland rice (cv. IR-72). 13N radiotracing showed that increased K+ supply reduces futile NH4+ cycling at the plasma membrane, diminishing the excessive rates of both unidirectional influx and efflux. Pharmacological testing showed that low-affinity NH4+ influx may be mediated by both K+ and non-selective cation channels. Suppression of NH4+ influx by K+ occurred within minutes of increasing K+ supply. Increased K+ reduced free [NH4+] in roots and shoots by 50-75%. Plant biomass was maximized on 10 mM NH4+ and 5 mM K+, with growth 160% higher than 10 mM NO3--grown plants, and 220% higher than plants grown at 10 mM NH4+ and 0.1 mM K+. Unlike in NH4+-sensitive barley, growth optimization was not attributed to a reduced energy cost of futile NH4+ cycling at the plasma membrane. Activities of the key enzymes glutamine synthetase (GS) and phosphoenolpyruvate carboxylase (PEPC) were strongly stimulated by elevated K+, mirroring plant growth and protein content. Improved plant performance through optimization of K+ and NH4+ is likely to be of substantial agronomic significance in the world’s foremost crop species.

We present the first characterization of K+ optimization of N uptake and metabolism in an NH4+-tolerant species, tropical lowland rice (cv. IR-72). 13N radiotracing showed that increased K+ supply reduces futile NH4+ cycling at the plasma membrane, diminishing the excessive rates of both unidirectional influx and efflux. Pharmacological testing showed that low-affinity NH4+ influx may be mediated by both K+ and non-selective cation channels. Suppression of NH4+ influx by K+ occurred within minutes of increasing K+ supply. Increased K+ reduced free [NH4+] in roots and shoots by 50-75%. Plant biomass was maximized on 10 mM NH4+ and 5 mM K+, with growth 160% higher than 10 mM NO3--grown plants, and 220% higher than plants grown at 10 mM NH4+ and 0.1 mM K+. Unlike in NH4+-sensitive barley, growth optimization was not attributed to a reduced energy cost of futile NH4+ cycling at the plasma membrane. Activities of the key enzymes glutamine synthetase (GS) and phosphoenolpyruvate carboxylase (PEPC) were strongly stimulated by elevated K+, mirroring plant growth and protein content. Improved plant performance through optimization of K+ and NH4+ is likely to be of substantial agronomic significance in the world’s foremost crop species.

>Magister Scientiae - MSc / The influx of infecteds into a population plays a critical role in HIV transmission. These infecteds are known to migrate from one region to another, thereby having some interaction with a host population. This interactive mobility or migration causes serious public health problems. In a very insightful paper by Shedlin et al. [51], the authors discover risk factors but also beneficial factors with respect to fighting human immunodeficiency virus (HIV) transmission, in the lifestyles of immigrants from different cultural backgrounds. These associated behavioral factors with cross-cultural migrations have not received adequate theoretical a attention. In this dissertation we use the compartmental model of Bhunu et al. [6] to form a new model of the HIV epidemic, to include the effect of infective immigrants in a given population. In fact, we first produce a deterministic model and provide a detailed analysis. Thereafter we introduce stochastic perturbations on the new model and study stability of the disease-free equilibrium (DFE) state. We investigate theoretically and computationally how cross-cultural migrations and public health education impacts on the HIV transmission, and how best to intervene in order to minimize the spread of the disease. In order to understand the long-time progression of the disease, we calculate the threshold parameter, known as the basic reproduction number, R0. The basic reproduction number has the property that if R0 is sufficiently small, usually R0 < 1, then the disease eventually vanishes from the population, but if R0 > 1, the disease persists in the population. We study the sensitivity of the basic reproduction number with respect to model parameters. In this regard, if R0 < 1, we show that the DFE is locally asymptotically stable. We also show global stability of the DFE using the Lyapunov method. We derive the endemic equilibrium points of our new model. We intend to counteract the negative effect of the influx of infecteds into a population with educational campaigns as a control strategy. In doing so, we employ optimal control theory to find an optimal intervention on HIV infection using educational campaigns as a basic input targeting the host population. Our aim is to reduce the total number of infecteds while minimizing the cost associated with the use of educational campaign on [0, T ]. We use Pontryagin’s maximum principle to characterize the optimal level of the control. We investigate the optimal education campaign strategy required to achieve the set objective of the intervention. The resulting optimality system is solved numerically using the Runge-Kutta fourth order method. We present numerical results obtained by simulating the optimality system using ODE-solvers in MATLAB program. We introduce randomness known as white noise into our newly formed model, and discuss the almost sure exponential stability of the disease-free equilibrium. Finally, we verify the analytical results through numerical simulations.

Le système de FitzHugh-Nagumo stochastique est un modèle qualitatif pour la propagation de l’influx nerveux dans un neurone. Ce système lent-rapide s’écrit εdxt = (xt - xt3 + yt) dt + √εσ1 dWt(1), dyt = (a - bxt - cyt) dt + σ2 dwt(2) où a, b et c sont des réels, ε est un petit réel positif, σ1 et σ2 sont deux réels positifs représentant l’intensité du bruit, Wt(1) et Wt(2) sont deux mouvements browniens standards indépendants. Dans cette thèse, nous étudions d’abord le système déterministe associé (σ1 = σ2 = 0) et montrons qu’il est excitable. Nous regardons ensuite le cas particulier où b = 0. Dans ce cas, le comportement au voisinage du point d’équilibre est le même que celui d’un autre modèle, celui de Morris-Lecar. Nous étudions alors la loi du temps de sortie de ce voisinage. Dans le cas général, après avoir mis en évidence trois principaux régimes, nous montrons des résultats généraux sur la distribution du nombre de petites oscillations N entre deux spikes consécutifs en introduisant une chaîne de Markov. Puis nous étudions le cas particulier du régime de bruit faible. / The stochastic FitzHugh-Nagumo equations is a qualitative model for the dynamics of neuronalaction potential. This slow-fast system is written εdxt = (xt - xt3 + yt) dt + √εσ1 dWt(1), dyt = (a - bxt - cyt) dt + σ2 dwt(2) where a, b and c are real numbers, ε is a small positive real number, σ1 et σ2 are two positivereal number representing the intensity of noise, Wt(1) et Wt(2) are two standard Brownian motion independent.In this thesis, we first study the associated deterministic system (σ1 = σ2 = 0) and we show this system is excitable. Then we are interested in the particular case b = 0. In this case, the behaviorin the neighborhood of the equilibrium is the same as the Morris-Lecar model. We study the law ofthe exit time of this neighborhood. In the general case, we show there are three main regimes. Westudy the distribution of the number of small oscillations N between two consecutive spikes using a substochastic Markov chain. Then we obtain results in the case of the weak-noise regime.

Until the introduction of administration boards in 1972-1973, the responsibility for administering the urban black townships in "white" South Africa was vested with the municipalities as agents of the Department of Bantu Administration and Development. The establishment of administration boards to replace the municipalities' Non-European Affairs Departments reflected the determination of the Department of Bantu Administration and Development to secure tighter direct control over the implementation of policy, particularly that affecting influx control and labour regulation. The decision to end municipal control was made after the report of the Van Rensburg Inter-Departmental Committee of Inquiry into Control Measures, which reported in 1967. The report's concern that influx control was not working as intended, coupled with doubts about the political autonomy of Opposition controlled municipalities, which dated back to the 1950s, were the major reasons for the introduction of administration boards.

Please read the abstract in the section 00front of this document / Thesis (DPhil (Medical Immunology))--University of Pretoria, 2006. / Immunology / unrestricted

The non-uniform distribution of the plant growth regulator (phytohormone) auxin is known to mediate many fundamental processes in plant development. Auxin is transported through the plant body either via vascular pathways or from cell to cell by specialized polar auxin transport machinery. This machinery consists of a balanced system of passive diffusion combined with the activities of auxin influx and efflux carriers. This work is focused on the processes that are involved in the uptake of auxin into plant cells. On the basis of molecular-biological and biochemical characterization, the function as an auxin influx carrier was confirmed for PaLAX1 protein from wild cherry (Prunus avium). The sequences of isolated cDNA of the PaLAX1 gene and of its protein product are highly similar to both the cDNAs and the corresponding protein products of the AUX1/LAX-type genes, coding for putative auxin influx carriers in model plant A. thaliana. On the level of organs and single cells, we have shown that the overproduction of PaLAX1 in transgenic lines resulted in an increase of the content of native auxin indole-3-acetic acid as well as of the uptake of synthetic auxin, 2,4-dichlorophenoxyacetic acid. Further, the mechanism of action of putative auxin influx inhibitors 1-naphthoxyacetic acid (1-NOA),...