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    Open Access
    A comparative study of selected aspects of corporate liability of directors under Swiss and South African law
    (2008) Mueller, Dominique Chantal; Rademeyer, Conrad
    Corporate liability of directors is a current issue all over the world due to the financial failures of corporations in the United States and Europe in the past years. The current proceedings in Switzerland against former directors of Swissair, who are accused of having caused the grounding of the airline in October 2001, attracts not only the attention of the Swiss public but also the interest of the neighbouring countries. In this dissertation I will first point out the relevant principles of the Swiss corporate law dealing with liability of directors and then compare the legal situation in Switzerland with the legal situation in South Africa. As the analysis of the whole corporate liability issue would go beyond the scope of this dissertation I will focus on Article 754 of the Swiss Code of Obligations (organ liability) and compare it with the South African grounds of liability of directors for breach of their fiduciary duties and their duty of care and skill.
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    Open Access
    Spatial and temporal variability in Acacia population dynamics
    (2008) Staver, A Carla; Bond, William J; February, Edmund C
    Variability in fire, herbivory, and climate facilitate the coexistence of trees and grasses in savannas and impact upon savanna structure, which also varies substantially both spatially and temporally. These features can shape savannas at an ecosystem and even at a global scale, but mechanisms for the effects of fire, herbivory, and climate variability on tree cover are often demographic at the tree population level. Sapling growth in particular has repeatedly been shown to be the limiting step, or 'bottleneck', in the establishment of trees in savannas. I set out to investigate how spatial and temporal variability in fire, herbivory, and climate shape population dynamics of a suite of common African savanna trees, the Acacia, in a landscape context. I carried out my field work in Hluhluwe iMfo lozi Park in KwaZulu Natal, South Africa, during 2006 and 2007. Fire, herbivory, and the grass layer were primary determinants of distributions and co-occurrence of Acacia species. They primarily affected saplings, indicating that sapling survival may determine distributions of adults. Moreover, communities were structured by species' direct interactions with fire and herbivory, rather than by competitive interactions with each other. Spatial heterogeneity in fire and herbivory resulted in an ecologically diverse suite of Acacia species. Even within the environments in which different species occurred, both fire and herbivory had the ability to directly suppress Acacia sapling growth and limit establishment of adult trees. Sapling growth and maturation, rather than seedling establishment or sapling mortality, appeared to be the limiting step. A herbivore exclusion experiment showed that at mesic sites, where growth rates were higher, browsing and fire acted together to limit sapling growth, while at semi-arid sites, ii browsing or fire alone was sufficient to prevent saplings growmg. Reductions in browsing resulted in increases in sapling growth, indicating that variability in herbivore pressure impacts adult establishment and tree population dynamics. A long-term study of establishment of Acacia trees using age estimation of adults via dendrochronology indicated that tree recruitment is not continuous at local or landscape scales. A. karroo recruitment occurred within the last 20 years during periods without fire on a local scale; however, on a landscape scale, decreases in fire frequency were linked to periods of drought. I was unable to link recruitment of A. nilotica and A. nigrescens directly to climate, fire or herbivore population records, but recruitment of both species appeared to have stopped in the 1970s. In mesic areas, dominance seemed to be shifting from A. nilotica to A. karroo, while in semi-arid areas, large A. nigrescens trees are not being replaced. This suggests that major shifts in species dominance and even savanna structure are characteristic of these savannas. Savannas are highly variable systems that are not adequately described by equilibrium ecology models. Non-equilibrium dynamics must form a more fundamental part both of theoretical savanna ecology and of savanna management.
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    Open Access
    Development of a prototype for user-driven email classification
    (2008) Wessels, David Johann; Marsden, Gary
    Enormous volumes of email are proliferated around the world every day, and a significant number of users believe that a large proportion of their time is being wasted dealing with the resultant inbox 'flooding'. This research studies existing email classification techniques which aim to reduce the burden of the burgeoning inbox. It then develops the first iteration of a prototype which makes use of sender-assisted classification techniques, having used HCI investigative techniques to develop a set of improvements to existing email clients. This prototype is then evaluated. The suggested improvements are incorporated into a second prototype based on the recommendations from the first prototype.
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    Open Access
    Solitons,spatiotemporal choas and synchronization in arrays of damped driven nonlinear oscillators
    (2008) Robinson,WML; Barashenkov, Igor; Alexeeva, Nora
    We explore periodic and chaotic motion in a soliton-bearing chain of nonlinear oscillators and study the effect of disorder on the spatiotemporal chaos. The chain we consider consists of torsionally coupled, damped, parametrically driven pendulums. We show that the amplitudes of the pendulums satisfy a system of equations in slow time, the "nonlinear Schrodinger (NLS) oscillators". The evolution of the chain of NLS oscillators is simulated numerically. Simulating the homogeneous chain, we demonstrate the existence of periodically oscillating solitons, the period-doubling sequence of transitions to temporal chaos and the degeneration into spatiotemporal chaos for larger driving strengths. ~ext, we explore the effect of introducing weak disorder in the simplest form, a single impurity, into the chain. We describe how a long impurity can induce a pinned soliton to form and prevent spatiotcmporal chaos, synchronizing the oscillators in the chain. Lastly, we study chains with several impurities in various configurations. Cases considered include chains with multiple impurities of different strengths, equal equidistant impurities (both long and short), and equal impurities which are positioned randomly along the chain. vVe show that all the previously reported features of the continuous NLS equation are reproduced in the dynamics of the discrete chain. Our results indicate that the dominant structures of the spatiotemporal chaos are unstable solitons. We show how spatiotemporally chaotic motion can be suppressed by disordering the chain through the inclusion of one or more impurities, synchronizing the oscillators. A comprehensive analysis of chains with identical equidistant long impu- rities reveals an unexpectedly complex relationship between the number and strength of impurities and the dynamics observed. As a result of disordering the positions of impurities, we find that oscillatiug solitons form between impurities when the gaps are large enough. The oscillations may be periodic or chaotic. Equidistant short impurities may also stabilize the chain. We conclude that for a 8et of irnpuritie8 to prevent spatiotemporal chaos from emerging in the array, the intervals between the impurities should be sufficiently small, and the stre11gth of the impuritic8 should be sufficiently large. The required number and strength of impurities depends on the oscillator parameters and the initial condition of the chain.
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    Open Access
    Urban livelihood
    (2021) Schmidt, Carl; Ewing, Kathryn
    Problem statement The CBD of Cape Town is found within the walled-in mountainous valley, commonly referred to as the City Bowl. Market forces are pushing small-scale businesses/craftsperson's from this economically vibrant area with very few affordable retail / workspace opportunities on offer. The residential component of the CBD has a similar set of problems with market forces. There are too few housing opportunities for the middle- and lower-income groups. Market forces perpetuate the narrative of developing housing opportunities for these income groups on the periphery of the metropole, far from economic activity. The Research Question How can underutilised state-owned properties along a key movement route in the Cape Town City Bowl be reimagined to promote economic diversity and inclusion? Proposed Goal Titled “Urban Livelihoods”, this project sets out to reimagine the economic centre of Cape Town, with inclusive, well-located housing and economic opportunities. Proposed Solution This project explores how we can stitch new designs into the existing fabric of the City Bowl of Cape Town, using well-located parcels of land and available buildings. Key well located state-owned sites are identified within economically vibrant neighbourhoods. These sites will be reimagined to envisage inclusive residential and economic opportunities within the CBD of Cape Town. Methods The researcher gathered information from interviews, site visit observations, mapping and sketching the CBD. This information was curated and formed the basis for the designs that followed. Design Conclusion The creative element of this project inspires an urban design framework to reinvigorate stagnant land or buildings and strategies to harness the productive energies of a city. Through these mechanisms, vibrant spaces will open and foster thriving communities. If these frameworks and strategies can be achieved, maintained, and yield inclusive growth then the project is a success