Place Identification : A Comparative Study

Place identification is the methodology of automatically detecting spatial regions or places that are meaningful to a user by analysing her location traces. Following this approach several algorithms have been proposed in the literature. Most of the algorithms perform well on a particular data set with suitable choice of parameter values. However, tuneable parameters make it difficult for an algorithm to generalise to data sets collected from different geographical locations, different periods of time or containing different activities. This thesis compares the generalisation performance of our proposed DPCluster algorithm along with six state-of-the-art place identification algorithms on twelve location data sets collected using Global Positioning System (GPS). Spatial and temporal variations present in the data help us to identify strengths and weaknesses of the place identification algorithms under study. We begin by discussing the notion of a place and its importance in location-aware computing. Next, we discuss different phases of the place identification process found in the literature followed by a thorough description of seven algorithms. After that, we define evaluation metrics and compare generalisation performance of individual place identification algorithms and report the results. The results indicate that the DPCluster algorithm performs superior to all other algorithms in terms of generalisation performance.

Species-based and community-level approaches to conservation prioritization

One major reason for the global decline of biodiversity is habitat loss and fragmentation. Conservation areas can be designed to reduce biodiversity loss, but as resources are limited, conservation efforts need to be prioritized in order to achieve best possible outcomes. The field of systematic conservation planning developed as a response to opportunistic approaches to conservation that often resulted in biased representation of biological diversity. The last two decades have seen the development of increasingly sophisticated methods that account for information about biodiversity conservation goals (benefits), economical considerations (costs) and socio-political constraints. In this thesis I focus on two general topics related to systematic conservation planning. First, I address two aspects of the question about how biodiversity features should be valued. (i) I investigate the extremely important but often neglected issue of differential prioritization of species for conservation. Species prioritization can be based on various criteria, and is always goal-dependent, but can also be implemented in a scientifically more rigorous way than what is the usual practice. (ii) I introduce a novel framework for conservation prioritization, which is based on continuous benefit functions that convert increasing levels of biodiversity feature representation to increasing conservation value using the principle that more is better. Traditional target-based systematic conservation planning is a special case of this approach, in which a step function is used for the benefit function. We have further expanded the benefit function framework for area prioritization to address issues such as protected area size and habitat vulnerability. In the second part of the thesis I address the application of community level modelling strategies to conservation prioritization. One of the most serious issues in systematic conservation planning currently is not the deficiency of methodology for selection and design, but simply the lack of data. Community level modelling offers a surrogate strategy that makes conservation planning more feasible in data poor regions. We have reviewed the available community-level approaches to conservation planning. These range from simplistic classification techniques to sophisticated modelling and selection strategies. We have also developed a general and novel community level approach to conservation prioritization that significantly improves on methods that were available before. This thesis introduces further degrees of realism into conservation planning methodology. The benefit function -based conservation prioritization framework largely circumvents the problematic phase of target setting, and allowing for trade-offs between species representation provides a more flexible and hopefully more attractive approach to conservation practitioners. The community-level approach seems highly promising and should prove valuable for conservation planning especially in data poor regions. Future work should focus on integrating prioritization methods to deal with multiple aspects in combination influencing the prioritization process, and further testing and refining the community level strategies using real, large datasets.

Memory Meanders : Place, Home and Commemoration in an Ex-Rhodesian Diaspora Community

Memory Meanders is an ethnographic analysis of a postcolonial migrant community, white former Rhodesians, who have emigrated from Zimbabwe to South Africa after Zimbabwe s independence in 1980. An estimated 100 000 whites left the country during the first years of independence. Majority of these emigrants settled in South Africa. In recent years President Mugabe s land redistribution program has inflicted forced expulsions and violence against white farmers and black farm workers, and instigated a new wave of emigration. Concerning the study of Southern Africa, my research is therefore very topical. In recent years there has been a growing concern to study postcolonialism as it unfolds in the lived realities of actual postcolonies. A rising interest has also been cast on colonial cultures and white colonials within complex power relationships. My research offers insight to these discussions by investigating the ways in which the colonial past affects and effects in the present activities and ideas of former colonials. The study also takes part in discussing fundamental questions concerning how diaspora communities socially construct their place in the world in relation to the place left behind, to their current places of dwelling and to the community in dispersal. In spite of Rhodesia s incontestable ending, it is held close by social practices; by thoughts and talks, by material displays, and by webs of meaningful relationships. Such social memory practices, I suggest, are fundamental to how the community understands itself. The vantage points from which I examine how the ex-Rhodesians reminisce about Rhodesia concern ideas and practices related to place, home and commemoration. I first focus on the processes of symbolic investment that go into understanding place and landscape in Rhodesia and ask how the once dwelled-in places, iconic landscapes and experiences within places are reminisced about in diaspora. Secondly, I examine how home both as a mundanely organized sphere of everyday lives and as an idea of belonging is culturally configured, and analyze how and if homes travel in diaspora. In the final ethnographic section I focus on commemorative practices. I first analyze how food and culturally specific festive occasions of commensality are connected to social and sensual memory, considering the unique ways in which food acts as a mnemonic trigger in a diaspora community. The second example concerns the celebration of a centenary of Rhodesia in 1990. Through this case I describe how the mnemonic power of commemoration rests on the fact that culturally meaningful experiences are bodily re-enacted. I show how habitual memory connected to performance is one example of how memory gets passed-on in non-textual ways.