Rule-based interactive assisted reinforcement learning
- Authors: Bignold, Adam
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Reinforcement Learning (RL) has seen increasing interest over the past few years, partially owing to breakthroughs in the digestion and application of external information. The use of external information results in improved learning speeds and solutions to more complex domains. This thesis, a collection of five key contributions, demonstrates that comparable performance gains to existing Interactive Reinforcement Learning methods can be achieved using less data, sourced during operation, and without prior verifcation and validation of the information's integrity. First, this thesis introduces Assisted Reinforcement Learning (ARL), a collective term referring to RL methods that utilise external information to leverage the learning process, and provides a non-exhaustive review of current ARL methods. Second, two advice delivery methods common in ARL, evaluative and informative, are compared through human trials. The comparison highlights how human engagement, accuracy of advice, agent performance, and advice utility differ between the two methods. Third, this thesis introduces simulated users as a methodology for testing and comparing ARL methods. Simulated users enable testing and comparing of ARL systems without costly and time-consuming human trials. While not a replacement for well-designed human trials, simulated users offer a cheap and robust approach to ARL design and comparison. Fourth, the concept of persistence is introduced to Interactive Reinforcement Learning. The retention and reuse of advice maximises utility and can lead to improved performance and reduced human demand. Finally, this thesis presents rule-based interactive RL, an iterative method for providing advice to an agent. Existing interactive RL methods rely on constant human supervision and evaluation, requiring a substantial commitment from the advice-giver. Rule-based advice can be provided proactively and be generalised over the state-space while remaining flexible enough to handle potentially inaccurate or irrelevant information. Ultimately, the thesis contributions are validated empirically and clearly show that rule-based advice signicantly reduces human guidance requirements while improving agent performance.
- Description: Doctor of Pholosophy
- Authors: Bignold, Adam
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Reinforcement Learning (RL) has seen increasing interest over the past few years, partially owing to breakthroughs in the digestion and application of external information. The use of external information results in improved learning speeds and solutions to more complex domains. This thesis, a collection of five key contributions, demonstrates that comparable performance gains to existing Interactive Reinforcement Learning methods can be achieved using less data, sourced during operation, and without prior verifcation and validation of the information's integrity. First, this thesis introduces Assisted Reinforcement Learning (ARL), a collective term referring to RL methods that utilise external information to leverage the learning process, and provides a non-exhaustive review of current ARL methods. Second, two advice delivery methods common in ARL, evaluative and informative, are compared through human trials. The comparison highlights how human engagement, accuracy of advice, agent performance, and advice utility differ between the two methods. Third, this thesis introduces simulated users as a methodology for testing and comparing ARL methods. Simulated users enable testing and comparing of ARL systems without costly and time-consuming human trials. While not a replacement for well-designed human trials, simulated users offer a cheap and robust approach to ARL design and comparison. Fourth, the concept of persistence is introduced to Interactive Reinforcement Learning. The retention and reuse of advice maximises utility and can lead to improved performance and reduced human demand. Finally, this thesis presents rule-based interactive RL, an iterative method for providing advice to an agent. Existing interactive RL methods rely on constant human supervision and evaluation, requiring a substantial commitment from the advice-giver. Rule-based advice can be provided proactively and be generalised over the state-space while remaining flexible enough to handle potentially inaccurate or irrelevant information. Ultimately, the thesis contributions are validated empirically and clearly show that rule-based advice signicantly reduces human guidance requirements while improving agent performance.
- Description: Doctor of Pholosophy
Seeds, soils and moisture : ecophysiology to inform mine site restoration in arid zones
- Authors: Duncan, Corrine
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Mining in arid regions of Australia is followed by restoration and rehabilitation efforts. However, attempts to reintroduce many woody plant species have been unsuccessful. Water is the key limiting resource to plant growth and seed germination in arid zones. In this thesis, I investigated ecophysiological processes that may help improve recruitment across novel arid landscapes. I tested seed traits and dormancy cues of eight keystone plants and found that six of them had non-dormant, rapidly germinating seeds; a trait we propose is an adaptation to the region’s unpredictable rainfall. To identify the germination niche of species, I incubated seeds under different temperatures and water potentials, and found drought avoidance to be an important survival strategy for arid species. I collected soil samples to compare biophysicochemical properties of reconstructed soils to remnant ecosystems, and found that the distribution of clay content in the reconstructed soils did not mirror the remnant soils, compromising their ability to sustain perennial vegetation. I also monitored soil moisture and found that soil reconstruction reduces rainfall infiltration and retention, and subsequently increases evaporation. The synthesis of these results demonstrate some of the limitations to successful restoration in these systems, such as (1) unknown dormancy cues and poor seed longevity, (2) infrequent and episodic plant recruitment due to water limitation, and (3) reduced hydrological function of reconstructed soils. The failure to reinstate hydrological function is the major constraint to ecological restoration in this arid zone. Nonetheless, results from this study suggest that restoration is possible through more strategic use of seed, careful selection of drought tolerant species, and increasing soil moisture. Further failures to reinstate ecosystem function and community dynamics in arid zones with reconstructed soils can be prevented by understanding the edaphic constraints to plant establishment, and ameliorating conditions to mimic ecohydrological processes in remnant ecosystems.
- Description: Doctor of Philosophy
- Authors: Duncan, Corrine
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Mining in arid regions of Australia is followed by restoration and rehabilitation efforts. However, attempts to reintroduce many woody plant species have been unsuccessful. Water is the key limiting resource to plant growth and seed germination in arid zones. In this thesis, I investigated ecophysiological processes that may help improve recruitment across novel arid landscapes. I tested seed traits and dormancy cues of eight keystone plants and found that six of them had non-dormant, rapidly germinating seeds; a trait we propose is an adaptation to the region’s unpredictable rainfall. To identify the germination niche of species, I incubated seeds under different temperatures and water potentials, and found drought avoidance to be an important survival strategy for arid species. I collected soil samples to compare biophysicochemical properties of reconstructed soils to remnant ecosystems, and found that the distribution of clay content in the reconstructed soils did not mirror the remnant soils, compromising their ability to sustain perennial vegetation. I also monitored soil moisture and found that soil reconstruction reduces rainfall infiltration and retention, and subsequently increases evaporation. The synthesis of these results demonstrate some of the limitations to successful restoration in these systems, such as (1) unknown dormancy cues and poor seed longevity, (2) infrequent and episodic plant recruitment due to water limitation, and (3) reduced hydrological function of reconstructed soils. The failure to reinstate hydrological function is the major constraint to ecological restoration in this arid zone. Nonetheless, results from this study suggest that restoration is possible through more strategic use of seed, careful selection of drought tolerant species, and increasing soil moisture. Further failures to reinstate ecosystem function and community dynamics in arid zones with reconstructed soils can be prevented by understanding the edaphic constraints to plant establishment, and ameliorating conditions to mimic ecohydrological processes in remnant ecosystems.
- Description: Doctor of Philosophy
Taking fire, making fire : settler colonial understandings of Aboriginal fire practices in Victoria, Australia
- Authors: McMaster, Sarah
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: In the State of Victoria, Australia, fire has a political dimension that is as vigorous and enduring as its physical presence. This thesis argues that in Victoria, European explorers and settler colonists persistently treated and depicted Aboriginal fire skills and practices in ways that were politically advantageous to themselves, and disadvantageous to Aboriginal peoples. Drawing from nineteenth century diaries, letters, recollections, newspaper articles and official records, this work uses Foucauldian theories to analyse the discourses that shaped and made possible the newcomers’ understandings of Aboriginal fire practices. It argues that explorers and settler colonists sought to replace Aboriginal peoples as Victoria’s fire managers and to restrict the opportunities Aboriginal peoples had to determine burning regimes. They did this physically, by prohibiting, and limiting attempts by Aboriginal peoples to continue precolonial fire practices. They also did it discursively, creating knowledge which constituted the practices as antiquated and incompatible with colonial enterprises, and by forming their own identity as expert settler Victorians, legitimately at home on the land. This thesis stresses that relationships of power between Aboriginal and European peoples were multidimensional and argues that in maintaining a position of dominance, the newcomers variously appropriated, emulated, feared and revered Aboriginal fire practices. It further argues that these efforts to disturb Aboriginal peoples using fire were fuelled only partially by the settler colonial perceptions that Aboriginal-managed fires presented unacceptable physical risks to humans and their assets. Efforts to disturb existing practices were additionally prompted by the newcomers’ political need to effect their seizure of territory, by demonstrating that it was they, not Aboriginal peoples, who controlled fire in Victoria. Drawing from settler colonial theory about the enduring nature of colonising structures and discourse, this thesis suggests that caution is needed to ensure the state’s contemporary use of Aboriginal fire practices does not further perpetuate settler colonial patterns of dominance and control.
- Description: Doctor of Philosophy
- Authors: McMaster, Sarah
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: In the State of Victoria, Australia, fire has a political dimension that is as vigorous and enduring as its physical presence. This thesis argues that in Victoria, European explorers and settler colonists persistently treated and depicted Aboriginal fire skills and practices in ways that were politically advantageous to themselves, and disadvantageous to Aboriginal peoples. Drawing from nineteenth century diaries, letters, recollections, newspaper articles and official records, this work uses Foucauldian theories to analyse the discourses that shaped and made possible the newcomers’ understandings of Aboriginal fire practices. It argues that explorers and settler colonists sought to replace Aboriginal peoples as Victoria’s fire managers and to restrict the opportunities Aboriginal peoples had to determine burning regimes. They did this physically, by prohibiting, and limiting attempts by Aboriginal peoples to continue precolonial fire practices. They also did it discursively, creating knowledge which constituted the practices as antiquated and incompatible with colonial enterprises, and by forming their own identity as expert settler Victorians, legitimately at home on the land. This thesis stresses that relationships of power between Aboriginal and European peoples were multidimensional and argues that in maintaining a position of dominance, the newcomers variously appropriated, emulated, feared and revered Aboriginal fire practices. It further argues that these efforts to disturb Aboriginal peoples using fire were fuelled only partially by the settler colonial perceptions that Aboriginal-managed fires presented unacceptable physical risks to humans and their assets. Efforts to disturb existing practices were additionally prompted by the newcomers’ political need to effect their seizure of territory, by demonstrating that it was they, not Aboriginal peoples, who controlled fire in Victoria. Drawing from settler colonial theory about the enduring nature of colonising structures and discourse, this thesis suggests that caution is needed to ensure the state’s contemporary use of Aboriginal fire practices does not further perpetuate settler colonial patterns of dominance and control.
- Description: Doctor of Philosophy
The impacts of climate change on trade and foreign direct investment flows
- Authors: Barua, Suborna
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: A growing body of climate economics research suggests that climate change affects production, prices, distribution structures, investments and national income. Studies further describe international trade and climate related investments as key activities in climate impact mitigation and adaptation. However, despite its increasing relevance, the empirical link between climate change and international trade and investment remains largely unexplored. This thesis investigates the climate change impacts on trade and foreign direct investment (FDI) flows using static and dynamic panel estimations covering 102 countries. The modelling uses temperature and precipitation variability to separately evaluate changes in international trade from 1962 to 2014, and in FDI inflows from 1995 to 2014. The trade impacts estimations consider exports of total merchandise, agriculture and six agricultural sectors; while controlling for income, comparative advantage, productivity, domestic and trade policies, and climate zones. The FDI impacts modelling evaluates total and sectoral inflows, while controlling for income, market size, infrastructure, openness, financial development, the global financial crisis and climate zones. Results show that climate change significantly affects both exports and FDI inflows. In particular, temperature affects merchandise exports, negatively at the global and developing country level, and positively in high-income countries. Agricultural exports are negatively affected by temperature. At the sectoral level, oil-seeds and dairy are mostly affected. Precipitation effects are limited and mostly negative for agriculture. The FDI world aggregate flows respond mostly positively to both temperature and precipitation, and static estimations indicate a FDI positive response in developing countries. Furthermore, FDI sectoral estimations indicate a differentiated response. Findings could inform the formulation of trade and investment policies, at the national and global level, in consideration to the differential impacts of climate change across sectors, regions and economic status. Furthermore, these estimates could be used in projections considering climate change as a determinant of trade and investment flows.
- Description: Doctor of Philosophy
- Authors: Barua, Suborna
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: A growing body of climate economics research suggests that climate change affects production, prices, distribution structures, investments and national income. Studies further describe international trade and climate related investments as key activities in climate impact mitigation and adaptation. However, despite its increasing relevance, the empirical link between climate change and international trade and investment remains largely unexplored. This thesis investigates the climate change impacts on trade and foreign direct investment (FDI) flows using static and dynamic panel estimations covering 102 countries. The modelling uses temperature and precipitation variability to separately evaluate changes in international trade from 1962 to 2014, and in FDI inflows from 1995 to 2014. The trade impacts estimations consider exports of total merchandise, agriculture and six agricultural sectors; while controlling for income, comparative advantage, productivity, domestic and trade policies, and climate zones. The FDI impacts modelling evaluates total and sectoral inflows, while controlling for income, market size, infrastructure, openness, financial development, the global financial crisis and climate zones. Results show that climate change significantly affects both exports and FDI inflows. In particular, temperature affects merchandise exports, negatively at the global and developing country level, and positively in high-income countries. Agricultural exports are negatively affected by temperature. At the sectoral level, oil-seeds and dairy are mostly affected. Precipitation effects are limited and mostly negative for agriculture. The FDI world aggregate flows respond mostly positively to both temperature and precipitation, and static estimations indicate a FDI positive response in developing countries. Furthermore, FDI sectoral estimations indicate a differentiated response. Findings could inform the formulation of trade and investment policies, at the national and global level, in consideration to the differential impacts of climate change across sectors, regions and economic status. Furthermore, these estimates could be used in projections considering climate change as a determinant of trade and investment flows.
- Description: Doctor of Philosophy
The making and placing of a personal view : Questions of place
- Authors: Farago, Anna
- Date: 2019
- Type: Text , Thesis , Masters
- Full Text:
- Description: The Making and Placing of a Personal View: Questions of Place uses various making methods to explore both the artist’s and others personal connection to place. The research investigates the intersection of memory, identity, and place. Memory is what informs personal history and collective futures. Identity, for the artist is as daughter, sister, mother, wife, friend, crafter, artist, woman and now widow. For others involved in the research, it is as Indigenous Elders, rangers and locals connected to specific sites. Place as which grounds and locates memories and landscapes that preoccupy the creative works. Memory and identity is explored materially through making, connecting art to place using craft’s historical connection with domestic and natural environments. Using the postmodern feminist geography of Doreen Massey, place is a site of flow and routes, rather than origins and roots. The relation between art and Massey’s notion of place is investigated as sympathetic to craft as a feminine epistemology. The creative work created comprises of four large textile patchworks, a series of small embroideries, and a pair of gouache paintings. The making of three large patchwork banner works were informed by conversational interviews conducted with Indigenous and non-Indigenous rangers. The banner works were installed for the duration of a weekend in Darebin Parklands in Alphington, Victoria in 2016 and at Pigeon House Mountain Didthul, Morton National Park, NSW in 2017. Performative and documentation photographs and videos were created in response to these installations. In addition a hand-stitched patchwork was slowly constructed over a year of grief and then used as a cloak and protective cloth in directed performative photos shot in the garden and on the roof of the artist’s home.
- Description: Masters by Research
- Authors: Farago, Anna
- Date: 2019
- Type: Text , Thesis , Masters
- Full Text:
- Description: The Making and Placing of a Personal View: Questions of Place uses various making methods to explore both the artist’s and others personal connection to place. The research investigates the intersection of memory, identity, and place. Memory is what informs personal history and collective futures. Identity, for the artist is as daughter, sister, mother, wife, friend, crafter, artist, woman and now widow. For others involved in the research, it is as Indigenous Elders, rangers and locals connected to specific sites. Place as which grounds and locates memories and landscapes that preoccupy the creative works. Memory and identity is explored materially through making, connecting art to place using craft’s historical connection with domestic and natural environments. Using the postmodern feminist geography of Doreen Massey, place is a site of flow and routes, rather than origins and roots. The relation between art and Massey’s notion of place is investigated as sympathetic to craft as a feminine epistemology. The creative work created comprises of four large textile patchworks, a series of small embroideries, and a pair of gouache paintings. The making of three large patchwork banner works were informed by conversational interviews conducted with Indigenous and non-Indigenous rangers. The banner works were installed for the duration of a weekend in Darebin Parklands in Alphington, Victoria in 2016 and at Pigeon House Mountain Didthul, Morton National Park, NSW in 2017. Performative and documentation photographs and videos were created in response to these installations. In addition a hand-stitched patchwork was slowly constructed over a year of grief and then used as a cloak and protective cloth in directed performative photos shot in the garden and on the roof of the artist’s home.
- Description: Masters by Research
The molecular characterisation of shigella spp. from Papua New Guinea and Pacific Island Nations
- Authors: Malau, Elisheba
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: In Papua New Guinea (PNG) and other low-middle income countries (LMICs) in Oceania, diarrhoea remains a leading cause of hospitalisation and death in children <5 years old; and is an important cause of illness in older children and adults. Shigella is one of four leading causes of diarrhoea globally and is likely a major cause of diarrhoea in Oceanic LMICs, particularly PNG. A survey was conducted among parents of children with diarrhoea in the PNG highlands, demonstrating limited access to, and application of, sanitation and hygiene; likely contributing to the transmission of Shigella and other pathogens in PNG. To better understand Shigella in Oceanic LMICs, multiple analyses of isolates from within PNG (n=38), far-northeastern Australia, and from travellers returning to Australia from Oceanic LMICs with shigellosis (n=34) were conducted. Antimicrobial susceptibility (by disc diffusion), detection of virulence genes by polymerase chain reaction (PCR) were conducted on all isolates, and whole genome sequencing (WGS) conducted on 63 isolates. Shigella spp. were commonly resistant to two or more classes of first-line antibiotics, with resistance more common in post-2010 relative to pre-2010 isolates. WGS was used to verify PCR detection of virulence genes, determine whether resistance could be predicted genetically, and conduct phylogenetic analysis of Shigella spp. in Oceania. WGS surpassed PCR in the detection of virulence genes, but correlated poorly with phenotypic antimicrobial resistance. Phylogenetic analysis revealed the intra- and inter-country relatedness. Three phylogenetic groups of S. flexneri co-exist in Oceanic LMICs (and far-northeastern Australia), the result of multiple incursions. Two lineages of S. sonnei were detected, one circulating in PNG and New Caledonia, and the other in various other countries including Fiji; with no geographical overlap of the two S. sonnei lineages. Incursions of Shigella into the Oceanic LMICs occur regularly, and are likely to occur again. This study provides evidence of the need for, and potential approach to, expanded surveillance of Shigella in the region.
- Description: Doctor of Philsophy
- Authors: Malau, Elisheba
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: In Papua New Guinea (PNG) and other low-middle income countries (LMICs) in Oceania, diarrhoea remains a leading cause of hospitalisation and death in children <5 years old; and is an important cause of illness in older children and adults. Shigella is one of four leading causes of diarrhoea globally and is likely a major cause of diarrhoea in Oceanic LMICs, particularly PNG. A survey was conducted among parents of children with diarrhoea in the PNG highlands, demonstrating limited access to, and application of, sanitation and hygiene; likely contributing to the transmission of Shigella and other pathogens in PNG. To better understand Shigella in Oceanic LMICs, multiple analyses of isolates from within PNG (n=38), far-northeastern Australia, and from travellers returning to Australia from Oceanic LMICs with shigellosis (n=34) were conducted. Antimicrobial susceptibility (by disc diffusion), detection of virulence genes by polymerase chain reaction (PCR) were conducted on all isolates, and whole genome sequencing (WGS) conducted on 63 isolates. Shigella spp. were commonly resistant to two or more classes of first-line antibiotics, with resistance more common in post-2010 relative to pre-2010 isolates. WGS was used to verify PCR detection of virulence genes, determine whether resistance could be predicted genetically, and conduct phylogenetic analysis of Shigella spp. in Oceania. WGS surpassed PCR in the detection of virulence genes, but correlated poorly with phenotypic antimicrobial resistance. Phylogenetic analysis revealed the intra- and inter-country relatedness. Three phylogenetic groups of S. flexneri co-exist in Oceanic LMICs (and far-northeastern Australia), the result of multiple incursions. Two lineages of S. sonnei were detected, one circulating in PNG and New Caledonia, and the other in various other countries including Fiji; with no geographical overlap of the two S. sonnei lineages. Incursions of Shigella into the Oceanic LMICs occur regularly, and are likely to occur again. This study provides evidence of the need for, and potential approach to, expanded surveillance of Shigella in the region.
- Description: Doctor of Philsophy
The molecular epidemiology of influenza in Cambodia
- Authors: Suttie, Annika
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Avian influenza viruses (AIVs) represent a risk to the health of humans and animals. The prevalence of AIVs in live bird markets in Cambodia is among the highest in the world, being detected in 45.5% of tested poultry in 2015. To better understand the potential risk presented by AIVs, this thesis investigated the genetic characteristics of AIVs circulating in Cambodia between 2014 to 2018; focusing on subtypes that pose the greatest risk to human and animal health (H5, H7 and H9). Highly pathogenic (HP) H5N1 clade 2.3.2.1c viruses and low pathogenic H9N2 BJ/94-like h9-4.2.5 clade viruses were the most frequently detected subtypes, and circulate endemically in Cambodia’s domestic poultry. Co-infections were detected and facilitated the production of two novel reassortant H5N1 AIVs with single genes from H9N2 viruses. Additionally, numerous intrasubtypic reassortment events were detected for H5 and H9 AIVs. This is concerning as reassortment events can rapidly produce novel viruses of public health risk. Phylogenetic analyses showed some genes of the Cambodian H5, H7 and H9 AIVs clustered with zoonotic viruses, suggesting a common origin. There are parallels between H5N1 and H9N2 AIVs detected in Cambodia and Vietnam, likely facilitated through the illegal trade of live poultry and/or the migration of wild birds. Molecular analyses showed H9 AIVs have major markers associated with adaptation to mammals; though during the study period the only human AIV cases were the result of HP H5N1. Molecular markers of resistance to adamantine antivirals was observed in 3% of H5 and 41% of H9 AIVs; however, both subtypes remain susceptible to first line antiviral treatment, neuraminidase inhibitors. The data presented in this thesis demonstrates that circulation of Cambodian AIVs represents a risk for the emergence of novel viruses. Interventions are urgently needed to mitigate the threat posed to poultry and humans.
- Description: Doctor of Philosophy
- Authors: Suttie, Annika
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Avian influenza viruses (AIVs) represent a risk to the health of humans and animals. The prevalence of AIVs in live bird markets in Cambodia is among the highest in the world, being detected in 45.5% of tested poultry in 2015. To better understand the potential risk presented by AIVs, this thesis investigated the genetic characteristics of AIVs circulating in Cambodia between 2014 to 2018; focusing on subtypes that pose the greatest risk to human and animal health (H5, H7 and H9). Highly pathogenic (HP) H5N1 clade 2.3.2.1c viruses and low pathogenic H9N2 BJ/94-like h9-4.2.5 clade viruses were the most frequently detected subtypes, and circulate endemically in Cambodia’s domestic poultry. Co-infections were detected and facilitated the production of two novel reassortant H5N1 AIVs with single genes from H9N2 viruses. Additionally, numerous intrasubtypic reassortment events were detected for H5 and H9 AIVs. This is concerning as reassortment events can rapidly produce novel viruses of public health risk. Phylogenetic analyses showed some genes of the Cambodian H5, H7 and H9 AIVs clustered with zoonotic viruses, suggesting a common origin. There are parallels between H5N1 and H9N2 AIVs detected in Cambodia and Vietnam, likely facilitated through the illegal trade of live poultry and/or the migration of wild birds. Molecular analyses showed H9 AIVs have major markers associated with adaptation to mammals; though during the study period the only human AIV cases were the result of HP H5N1. Molecular markers of resistance to adamantine antivirals was observed in 3% of H5 and 41% of H9 AIVs; however, both subtypes remain susceptible to first line antiviral treatment, neuraminidase inhibitors. The data presented in this thesis demonstrates that circulation of Cambodian AIVs represents a risk for the emergence of novel viruses. Interventions are urgently needed to mitigate the threat posed to poultry and humans.
- Description: Doctor of Philosophy
The nature of professional small business advisor knowledge and the knowledge transmission process : A regional Australian perspective
- Authors: Labas, Alan
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis specifically examines the relationship between professional business advisor (PBA) knowledge and the knowledge transmission actions undertaken by such advisors when addressing the knowledge requirements of businesses, specifically Regional Australian small businesses. The thesis adopts a qualitative research approach to explore perceptions of individuals who provide advisory services to small businesses, within the context of Regional Australia. The analysis undertaken is a practical application of the critical realist research paradigm to explain how human agency, social structures, and mechanisms interact in the process of creating a knowledge transmission event by PBAs. The conceptual framework developed in this thesis brings together key concepts from scholarly research disciplines of knowledge management, information management, communications, services marketing and business advice. The conceptual framework reflects the research aims and provides the basis for the research methodology. The framework is of a unique critical realist research design that allows the study to progress through sequential world views. Each world view allows the continual broadening of the reality being studied, enabling more focused answers to the research questions posed. This study focuses on PBAs who service small businesses operating in four inner regional and two outer regional locations within the State of Victoria. Over the six regions, a total of 29 face-to-face interviews were conducted, along with one focus group in each region. The findings from this database, using the conceptual framework as a guide, identified a complex, heterogeneous, open environment in which PBA knowledge transmission occurs. This research process recognises PBAs as social structures with causal powers whose knowledge stock is the primary mechanism through which these powers are exercised to generate a knowledge transmission event. A significant conclusion emerges that PBA tacit (and not explicit) knowledge is a conditional mechanism which gate-keeps whether the PBA knowledge transmission event is enacted.
- Description: Doctor of Philosophy
- Authors: Labas, Alan
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis specifically examines the relationship between professional business advisor (PBA) knowledge and the knowledge transmission actions undertaken by such advisors when addressing the knowledge requirements of businesses, specifically Regional Australian small businesses. The thesis adopts a qualitative research approach to explore perceptions of individuals who provide advisory services to small businesses, within the context of Regional Australia. The analysis undertaken is a practical application of the critical realist research paradigm to explain how human agency, social structures, and mechanisms interact in the process of creating a knowledge transmission event by PBAs. The conceptual framework developed in this thesis brings together key concepts from scholarly research disciplines of knowledge management, information management, communications, services marketing and business advice. The conceptual framework reflects the research aims and provides the basis for the research methodology. The framework is of a unique critical realist research design that allows the study to progress through sequential world views. Each world view allows the continual broadening of the reality being studied, enabling more focused answers to the research questions posed. This study focuses on PBAs who service small businesses operating in four inner regional and two outer regional locations within the State of Victoria. Over the six regions, a total of 29 face-to-face interviews were conducted, along with one focus group in each region. The findings from this database, using the conceptual framework as a guide, identified a complex, heterogeneous, open environment in which PBA knowledge transmission occurs. This research process recognises PBAs as social structures with causal powers whose knowledge stock is the primary mechanism through which these powers are exercised to generate a knowledge transmission event. A significant conclusion emerges that PBA tacit (and not explicit) knowledge is a conditional mechanism which gate-keeps whether the PBA knowledge transmission event is enacted.
- Description: Doctor of Philosophy
The relationship between business incubator services and the psychological capital of tenants
- Authors: Ollerenshaw, Alison
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Business incubators (BI) provide a supportive environment for new tenant businesses to grow to independence. Incubators offer characteristic services including (a) space, physical resources, and infrastructure; (b) business support services, (c) networking; and, (d) structured selection, entry, and exit. Despite the global growth in incubator facilities, complemented by extensive research, knowledge gaps remain. Little research has examined the relationship between the characteristic services at incubators and tenants’ psychological capital; a higher-order construct representing an individual’s positive psychological state of development that includes hope, efficacy, resilience, and optimism. Preliminary examination of the characteristic services at business incubators show analogies with interventions for developing psychological capital. Two research studies were designed to examine these relationships. In the first study, survey (n = 30) and interview data (n = 12) were collected from incubator tenants to examine the existence of a relationship between the four characteristic services at business incubators and tenants’ psychological capital, their hope, efficacy, resilience, and optimism. The survey data confirmed the existence of a relationship between three incubator services – space, physical resources, and infrastructure, business support services, and networking – and tenants’ psychological capital. Tenants’ narrative experiences confirmed that these same three incubator services support tenants’ hope, efficacy, resilience, and optimism. This finding implies that the three incubator services contribute to, and augment tenants’ positive psychological states, which is then manifest in their positive behaviours and attitudes towards their business. To further elucidate these relationships a second study was conducted. Data from surveys (n = 75) and interviews (n = 28) with incubators managers also confirmed that space, physical resources, and infrastructure, business support services, and networking were analogous with methods that support tenants’ hope, efficacy, resilience, and optimism. These findings infer that incubator managers are not only instrumental in delivering these three characteristic services at incubators but are integral in optimising these services to benefit tenants’ hope, efficacy, resilience, and optimism. This current research provides robust evidence that three characteristic services at incubators are associated with tenants’ psychological capital, hope, efficacy, resilience, and optimism. These research findings are novel, and the implications for the incubator industry wide-ranging, with evidence indicating that the three characteristic services at incubators are analogous with interventions that support tenants’ psychological capital, and that incubator staff are integral to the delivery of these characteristic services. New directions for the incubator industry are proposed that include establishing a consistent approach to delivering the characteristic services at incubators that support incubator tenants’ businesses, and their positive psychological development.
- Description: Doctor of Philosophy
- Authors: Ollerenshaw, Alison
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Business incubators (BI) provide a supportive environment for new tenant businesses to grow to independence. Incubators offer characteristic services including (a) space, physical resources, and infrastructure; (b) business support services, (c) networking; and, (d) structured selection, entry, and exit. Despite the global growth in incubator facilities, complemented by extensive research, knowledge gaps remain. Little research has examined the relationship between the characteristic services at incubators and tenants’ psychological capital; a higher-order construct representing an individual’s positive psychological state of development that includes hope, efficacy, resilience, and optimism. Preliminary examination of the characteristic services at business incubators show analogies with interventions for developing psychological capital. Two research studies were designed to examine these relationships. In the first study, survey (n = 30) and interview data (n = 12) were collected from incubator tenants to examine the existence of a relationship between the four characteristic services at business incubators and tenants’ psychological capital, their hope, efficacy, resilience, and optimism. The survey data confirmed the existence of a relationship between three incubator services – space, physical resources, and infrastructure, business support services, and networking – and tenants’ psychological capital. Tenants’ narrative experiences confirmed that these same three incubator services support tenants’ hope, efficacy, resilience, and optimism. This finding implies that the three incubator services contribute to, and augment tenants’ positive psychological states, which is then manifest in their positive behaviours and attitudes towards their business. To further elucidate these relationships a second study was conducted. Data from surveys (n = 75) and interviews (n = 28) with incubators managers also confirmed that space, physical resources, and infrastructure, business support services, and networking were analogous with methods that support tenants’ hope, efficacy, resilience, and optimism. These findings infer that incubator managers are not only instrumental in delivering these three characteristic services at incubators but are integral in optimising these services to benefit tenants’ hope, efficacy, resilience, and optimism. This current research provides robust evidence that three characteristic services at incubators are associated with tenants’ psychological capital, hope, efficacy, resilience, and optimism. These research findings are novel, and the implications for the incubator industry wide-ranging, with evidence indicating that the three characteristic services at incubators are analogous with interventions that support tenants’ psychological capital, and that incubator staff are integral to the delivery of these characteristic services. New directions for the incubator industry are proposed that include establishing a consistent approach to delivering the characteristic services at incubators that support incubator tenants’ businesses, and their positive psychological development.
- Description: Doctor of Philosophy
The role of Zn2+ in insulin signalling and muscle atrophy
- Authors: Maier, Michelle
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Zn2+ is a broadly utilised ion in biology that has important catalytic, structural and regulatory roles within the cell. Zn2+ distribution in cells is maintained by zinc transporters, Zips and ZnTs, and disruptions in levels of Zn2+ have been associated with insulin resistance and muscle atrophy disorders. Zn2+ and reactive oxygen species (ROS) interact through inhibition of protein tyrosine phosphatases and ROS-mediated oxidation of the metal-binding metallothioneins (Mts) causing release of bound Zn2+, however the precise mechanisms are unclear. In the first study of this thesis addition of inhibitors of ROS-generating enzymes, superoxide dismutase 1 (SOD1) and NADPH oxidase 1 (NOX1) showed that only SOD1 inhibition increased short-term insulin-mediated Zn2+ release and increased the expression of Mt1 and 2. These results may suggest that ROS, in particular O2- accumulation through inhibition of SOD1, plays a role in insulin-mediated Zn2+ release. Inhibiting SOD1 prevents the conversion of O2- to H2O2 causing an accumulation of O2- in the cell which oxidises Mts to release Zn2+, thereby increasing Zn2+ levels within the cell. Manipulation of the expression of the zinc transporter Zip-7 has previously been shown to modulate cell signalling and glucose metabolism in C2C12 skeletal muscle cells, warranting further investigation into the role of Zn2+ within insulin signalling. Reducing Zip-7 expression when NOX1 was inhibited caused a decrease in Mt2 expression in response to insulin suggesting an interaction between insulin, Zip-7 and NOX1 activity but this requires further investigation. Skeletal muscle atrophy is a clinical symptom of insulin resistance and diabetes. Muscle atrophy is associated with increases in circulating glucocorticoid levels and accumulation of Zn2+ in muscle. This study investigates if Zn2+ homeostasis is disrupted in glucocorticoid-induced atrophy using C2C12 skeletal muscle cells treated with Dexamethasone (DEX) and iv insulin. Results demonstrate DEX-induced atrophy significantly increased the gene expression of the Mt1&2 and decreased glycogen accumulation when treated with insulin. Both confocal microscopy and flow cytometry showed significant increases in free cellular Zn2+ after DEX treatment. Notably, free Zn2+ levels observed with confocal microscopy increased after insulin treatment in control cells but decreased in DEX treated cells. Total cellular Zn2+ was increased by DEX treatment. This demonstrates that DEX causes Zn2+ accumulation in muscle cells and disrupts both Zn2+ homeostasis through blocking insulin-induced Zn2+ release, and insulin-induced glycogen synthesis. This raised the question of whether the same effects of atrophy on Zn2+ homeostasis apply to other cell systems. To investigate this, we examined adipose cells given that these too are involved in insulin resistance and muscle atrophy disorders. In this study we found similar increases in mRNA abundance of Mt1 & 2. Confocal microscopy revealed that DEX treatment caused changes in the distribution of free Zn2+ within peri-nuclear and cytosolic regions of the cell upon stimulation with insulin. Furthermore, investigation into morphometric changes using Oil Red O staining and particle analysis through Coherent Anti-Stokes Ramen Spectrophotometry (CARS) microscopy showed changes in cell and lipid droplet size consistent with reduced lipid turnover in DEX treated cells. These results highlight a potential mechanistic role for Zn2+ in the development of atrophy in 3T3-L1 adipocytes where increased free Zn2+ and its redistribution in cells may inhibit lipid metabolism downstream of insulin signalling. These findings show that insulin-induced Zn2+ release is disrupted by glucocorticoids and this is associated with insulin resistance. Restoring control of Zn2+ homeostasis, possibly through controlling oxidation or manipulating Zn2+ levels directly, may prove beneficial in metabolic disease states such as diabetes.
- Description: Doctor of Philosophy
- Authors: Maier, Michelle
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Zn2+ is a broadly utilised ion in biology that has important catalytic, structural and regulatory roles within the cell. Zn2+ distribution in cells is maintained by zinc transporters, Zips and ZnTs, and disruptions in levels of Zn2+ have been associated with insulin resistance and muscle atrophy disorders. Zn2+ and reactive oxygen species (ROS) interact through inhibition of protein tyrosine phosphatases and ROS-mediated oxidation of the metal-binding metallothioneins (Mts) causing release of bound Zn2+, however the precise mechanisms are unclear. In the first study of this thesis addition of inhibitors of ROS-generating enzymes, superoxide dismutase 1 (SOD1) and NADPH oxidase 1 (NOX1) showed that only SOD1 inhibition increased short-term insulin-mediated Zn2+ release and increased the expression of Mt1 and 2. These results may suggest that ROS, in particular O2- accumulation through inhibition of SOD1, plays a role in insulin-mediated Zn2+ release. Inhibiting SOD1 prevents the conversion of O2- to H2O2 causing an accumulation of O2- in the cell which oxidises Mts to release Zn2+, thereby increasing Zn2+ levels within the cell. Manipulation of the expression of the zinc transporter Zip-7 has previously been shown to modulate cell signalling and glucose metabolism in C2C12 skeletal muscle cells, warranting further investigation into the role of Zn2+ within insulin signalling. Reducing Zip-7 expression when NOX1 was inhibited caused a decrease in Mt2 expression in response to insulin suggesting an interaction between insulin, Zip-7 and NOX1 activity but this requires further investigation. Skeletal muscle atrophy is a clinical symptom of insulin resistance and diabetes. Muscle atrophy is associated with increases in circulating glucocorticoid levels and accumulation of Zn2+ in muscle. This study investigates if Zn2+ homeostasis is disrupted in glucocorticoid-induced atrophy using C2C12 skeletal muscle cells treated with Dexamethasone (DEX) and iv insulin. Results demonstrate DEX-induced atrophy significantly increased the gene expression of the Mt1&2 and decreased glycogen accumulation when treated with insulin. Both confocal microscopy and flow cytometry showed significant increases in free cellular Zn2+ after DEX treatment. Notably, free Zn2+ levels observed with confocal microscopy increased after insulin treatment in control cells but decreased in DEX treated cells. Total cellular Zn2+ was increased by DEX treatment. This demonstrates that DEX causes Zn2+ accumulation in muscle cells and disrupts both Zn2+ homeostasis through blocking insulin-induced Zn2+ release, and insulin-induced glycogen synthesis. This raised the question of whether the same effects of atrophy on Zn2+ homeostasis apply to other cell systems. To investigate this, we examined adipose cells given that these too are involved in insulin resistance and muscle atrophy disorders. In this study we found similar increases in mRNA abundance of Mt1 & 2. Confocal microscopy revealed that DEX treatment caused changes in the distribution of free Zn2+ within peri-nuclear and cytosolic regions of the cell upon stimulation with insulin. Furthermore, investigation into morphometric changes using Oil Red O staining and particle analysis through Coherent Anti-Stokes Ramen Spectrophotometry (CARS) microscopy showed changes in cell and lipid droplet size consistent with reduced lipid turnover in DEX treated cells. These results highlight a potential mechanistic role for Zn2+ in the development of atrophy in 3T3-L1 adipocytes where increased free Zn2+ and its redistribution in cells may inhibit lipid metabolism downstream of insulin signalling. These findings show that insulin-induced Zn2+ release is disrupted by glucocorticoids and this is associated with insulin resistance. Restoring control of Zn2+ homeostasis, possibly through controlling oxidation or manipulating Zn2+ levels directly, may prove beneficial in metabolic disease states such as diabetes.
- Description: Doctor of Philosophy
Three-dimensional numerical study on the batter instability mechanism of Maddingley Brown Coal Open Pit, Victoria, Australia using PLAXIS 3D
- Authors: Zhao, Lei
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: With the increased size of excavation due to long-term open cut mining, batter instability has become a major geo-hazard in Victorian Brown Coal Open Pits where facilitate some largest brown coal mining operations in the world. Block failure is a unique failure mode in Victorian brown coal mines, which is often associated with cracks and rainfall. Maddingley Brown Coal Mine (MBC) is located in Bacchus Marsh, Victoria, Australia. Slope instability has also been a major geo-problem since the open pit mining commenced in MBC in 1940s. Making clear the cracking mechanism and the correlations between rainfall and batter instability have important implications in better understanding and predicting batter failures in Victorian brown coal mines. In this research, three-dimensional geologic models were developed to investigate the mechanism of brown coal batter instability. The finite element program encoded in Plaxis 3D was employed to conduct the complex two-phase (fluid-solid) coupled numerical simulations. The results revealed the cracking mechanism of coal batter and the effects of rainfall on batter stability. It was found that the brown coal batter with overburden tends to lead a circular critical path while the batter after overburden removal shows a trend of block sliding as interpreted by the shear and tensile strains simulated. The existence of joints and the hydrostatic water pressure in the joints could adversely affect the stability of brown coal batter towards block failure. Precipitation can increase the deformation, excess pore pressure, total pore pressure, active pressure and decrease the matric suction, and thereby decrease the shear strength, effective stress, and batter stability. The results from the three-dimensional hydro-mechanically coupled finite element study were well agreed with the field monitored data, theoretical calculations, and Victorian brown coal mining experience.
- Description: Doctor of Philosophy
- Authors: Zhao, Lei
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: With the increased size of excavation due to long-term open cut mining, batter instability has become a major geo-hazard in Victorian Brown Coal Open Pits where facilitate some largest brown coal mining operations in the world. Block failure is a unique failure mode in Victorian brown coal mines, which is often associated with cracks and rainfall. Maddingley Brown Coal Mine (MBC) is located in Bacchus Marsh, Victoria, Australia. Slope instability has also been a major geo-problem since the open pit mining commenced in MBC in 1940s. Making clear the cracking mechanism and the correlations between rainfall and batter instability have important implications in better understanding and predicting batter failures in Victorian brown coal mines. In this research, three-dimensional geologic models were developed to investigate the mechanism of brown coal batter instability. The finite element program encoded in Plaxis 3D was employed to conduct the complex two-phase (fluid-solid) coupled numerical simulations. The results revealed the cracking mechanism of coal batter and the effects of rainfall on batter stability. It was found that the brown coal batter with overburden tends to lead a circular critical path while the batter after overburden removal shows a trend of block sliding as interpreted by the shear and tensile strains simulated. The existence of joints and the hydrostatic water pressure in the joints could adversely affect the stability of brown coal batter towards block failure. Precipitation can increase the deformation, excess pore pressure, total pore pressure, active pressure and decrease the matric suction, and thereby decrease the shear strength, effective stress, and batter stability. The results from the three-dimensional hydro-mechanically coupled finite element study were well agreed with the field monitored data, theoretical calculations, and Victorian brown coal mining experience.
- Description: Doctor of Philosophy
Time experience and judgement in depression : A theory of isomorphic general relativity (TIGR)
- Authors: Kent, Lachlan
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis presents studies assessing aspects of time experience and judgement in depression. It focuses on a phenomenon called time dilation, which is the perception of slow temporal flow in conscious experience. This thesis by publication explains a novel theory of time dilation in depression, called the Theory of Isomorphic General Relativity (TIGR), and elaborates this theory to propose a general framework for consciousness and cognition according to timescale. The final outcome is a dual-pronged theory of time consciousness and the experience of time dilation in depression that has the same form as Einstein’s (1920) general theory of relativity. The thesis begins with a published paper called “Duration perception versus perception duration: A proposed model for the consciously experienced moment” (Kent, 2019). This paper defines temporal flow in conscious experience in terms of an interval of time perception known as the ‘experienced moment’ (Wittmann, 2011). In this paper, I reviewed evidence for a view of time dilation in depression that is distinct from either immediate sensory integration or working memory (WM) activity. The thesis continues with a second published paper called “Time dilation and acceleration in depression” (Kent, Van Doorn, & Klein, 2019) that reviews the literature specific to time perception in depression, and meta-analytically tests the preceding definition of time dilation within the experienced moment. This paper also details the experimental methodology used and proposes the TIGR as a descriptive and explanatory theory of time perception. xx The third published paper, “Bayes, time perception, and relativity: The central role of hopelessness” (Kent, Van Doorn, Hohwy, & Klein, 2019), formulates and tests the TIGR in a time perception experiment using the methodology outlined in the second paper. The time judgement and experience data of 64 participants, with and without sub-clinical symptoms of depression, were analysed using a statistical version of a Bayesian prediction error minimisation framework called ‘distrusting the present’ (Hohwy, Paton, & Palmer, 2016). The results showed that hopelessness was associated with slower time experience, while arousal was associated with faster time experience. The paper also supported the use of a relative difference equation to model these effects. This relative difference equation has the same general form as a basic general relativity equation used to calculate time dilation due to gravity, called the Schwarzschild metric (Schwarzschild, 1916). The fourth paper, “Time perception in depression: A perceived delay cues feelings of hopelessness” (Kent, Van Doorn, Hohwy, & Klein, under review), is under review by the journal Acta Psychologica. It looks more closely at the experimental effect reported in the third paper to explore the clinical implications of an increase in hopelessness caused by a brief time production task. The analysis showed that a particular sub-factor of the Beck Hopelessness Scale (BHS) called ‘feelings of hopelessness’ was more affected than other facets of hopelessness (Beck, Weissman, Lester, & Trexler, 1974). The fifth paper, “Systema temporis: A time-based dimensional framework for consciousness and cognition” (Kent, Van Doorn, & Klein, under review), is currently under review by the journal Consciousness and Cognition. In this paper, we extend elements of the TIGR related to consciousness in the first four papers xxi to argue that time consciousness can be used to systematise aspects of consciousness and cognition. The paper proposes a hierarchical framework that reflects the commonly-conceived structure of memory, intelligence, and emotional intelligence. This framework integrates aspects of consciousness including experience, wakefulness, and self-consciousness. The final paper, submitted to the journal Personality and Social Psychology Review and entitled “Systema psyches: A time-based framework for consciousness, cognition and related psychological and social theories” (Kent, Van Doorn, & Klein, submitted) extends the ‘Systema Temporis’ paper to incorporate extended timeframes and theories of social cognition including personality, cognitive and moral development, and personal values. The analysis suggests that time consciousness is also a facet of collective experience and so, in framing the closing discussion around time dilation in depression, the thesis concludes that the TIGR extends beyond the narrow domain of individual psychopathology to incorporate timescales of collective memory and human evolution.
- Description: Doctor of Philosophy
- Authors: Kent, Lachlan
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: This thesis presents studies assessing aspects of time experience and judgement in depression. It focuses on a phenomenon called time dilation, which is the perception of slow temporal flow in conscious experience. This thesis by publication explains a novel theory of time dilation in depression, called the Theory of Isomorphic General Relativity (TIGR), and elaborates this theory to propose a general framework for consciousness and cognition according to timescale. The final outcome is a dual-pronged theory of time consciousness and the experience of time dilation in depression that has the same form as Einstein’s (1920) general theory of relativity. The thesis begins with a published paper called “Duration perception versus perception duration: A proposed model for the consciously experienced moment” (Kent, 2019). This paper defines temporal flow in conscious experience in terms of an interval of time perception known as the ‘experienced moment’ (Wittmann, 2011). In this paper, I reviewed evidence for a view of time dilation in depression that is distinct from either immediate sensory integration or working memory (WM) activity. The thesis continues with a second published paper called “Time dilation and acceleration in depression” (Kent, Van Doorn, & Klein, 2019) that reviews the literature specific to time perception in depression, and meta-analytically tests the preceding definition of time dilation within the experienced moment. This paper also details the experimental methodology used and proposes the TIGR as a descriptive and explanatory theory of time perception. xx The third published paper, “Bayes, time perception, and relativity: The central role of hopelessness” (Kent, Van Doorn, Hohwy, & Klein, 2019), formulates and tests the TIGR in a time perception experiment using the methodology outlined in the second paper. The time judgement and experience data of 64 participants, with and without sub-clinical symptoms of depression, were analysed using a statistical version of a Bayesian prediction error minimisation framework called ‘distrusting the present’ (Hohwy, Paton, & Palmer, 2016). The results showed that hopelessness was associated with slower time experience, while arousal was associated with faster time experience. The paper also supported the use of a relative difference equation to model these effects. This relative difference equation has the same general form as a basic general relativity equation used to calculate time dilation due to gravity, called the Schwarzschild metric (Schwarzschild, 1916). The fourth paper, “Time perception in depression: A perceived delay cues feelings of hopelessness” (Kent, Van Doorn, Hohwy, & Klein, under review), is under review by the journal Acta Psychologica. It looks more closely at the experimental effect reported in the third paper to explore the clinical implications of an increase in hopelessness caused by a brief time production task. The analysis showed that a particular sub-factor of the Beck Hopelessness Scale (BHS) called ‘feelings of hopelessness’ was more affected than other facets of hopelessness (Beck, Weissman, Lester, & Trexler, 1974). The fifth paper, “Systema temporis: A time-based dimensional framework for consciousness and cognition” (Kent, Van Doorn, & Klein, under review), is currently under review by the journal Consciousness and Cognition. In this paper, we extend elements of the TIGR related to consciousness in the first four papers xxi to argue that time consciousness can be used to systematise aspects of consciousness and cognition. The paper proposes a hierarchical framework that reflects the commonly-conceived structure of memory, intelligence, and emotional intelligence. This framework integrates aspects of consciousness including experience, wakefulness, and self-consciousness. The final paper, submitted to the journal Personality and Social Psychology Review and entitled “Systema psyches: A time-based framework for consciousness, cognition and related psychological and social theories” (Kent, Van Doorn, & Klein, submitted) extends the ‘Systema Temporis’ paper to incorporate extended timeframes and theories of social cognition including personality, cognitive and moral development, and personal values. The analysis suggests that time consciousness is also a facet of collective experience and so, in framing the closing discussion around time dilation in depression, the thesis concludes that the TIGR extends beyond the narrow domain of individual psychopathology to incorporate timescales of collective memory and human evolution.
- Description: Doctor of Philosophy
To Wandiligong : a visual journey through memory, time, space, light, landscape and fourteen layers of glass
- Authors: Murray, Kathleen
- Date: 2019
- Type: Text , Thesis , Masters
- Full Text:
- Description: This research project examines the process of conceptualisation and its effects on the development of layers of meaning in a visual context. It explores a journey over time, within an observed environment. It explores the conceptual processes which, like a physical journey, runs through many landscapes. Memory and emotion, analysis and observation, recording and interpretation and as a final destination, the practical application in the making of the pictures. This exegesis compares the differences between the theoretical stances artists have taken in the pursuit of creating work based on the depiction of the landscape. It considers a variety of approaches to image and meaning and determines the effect of disruption as it relates to art practice over centuries and to my own practice. Throughout the work there is an exploration of the different forms of disruption on the landscape, from colonisation through to the visual effects of a changing climate. Consideration is given to the similarities and differences between the practices of visual art and communication design particularly in relation to the role of the audience. The process of research and experimentation in the making of 16 digitally augmented inkjet print, photographic images and an accompanying story map drawing of the journey is described. This involved the investigation of the conceptual development processes and approaches in relation to landscape imagery and the effect of a changing climate on their visual outcomes. The results of my experimentation in capturing images through drawing and photography using graphite pencils and paper and a camera, in a car moving through the landscape, are described. This is followed by a description of my experimentation of the use of a disruptive digital drawing application on photographic images located within an iPad and how the resulting images were conceptualised and created.
- Description: Masters by Research
- Authors: Murray, Kathleen
- Date: 2019
- Type: Text , Thesis , Masters
- Full Text:
- Description: This research project examines the process of conceptualisation and its effects on the development of layers of meaning in a visual context. It explores a journey over time, within an observed environment. It explores the conceptual processes which, like a physical journey, runs through many landscapes. Memory and emotion, analysis and observation, recording and interpretation and as a final destination, the practical application in the making of the pictures. This exegesis compares the differences between the theoretical stances artists have taken in the pursuit of creating work based on the depiction of the landscape. It considers a variety of approaches to image and meaning and determines the effect of disruption as it relates to art practice over centuries and to my own practice. Throughout the work there is an exploration of the different forms of disruption on the landscape, from colonisation through to the visual effects of a changing climate. Consideration is given to the similarities and differences between the practices of visual art and communication design particularly in relation to the role of the audience. The process of research and experimentation in the making of 16 digitally augmented inkjet print, photographic images and an accompanying story map drawing of the journey is described. This involved the investigation of the conceptual development processes and approaches in relation to landscape imagery and the effect of a changing climate on their visual outcomes. The results of my experimentation in capturing images through drawing and photography using graphite pencils and paper and a camera, in a car moving through the landscape, are described. This is followed by a description of my experimentation of the use of a disruptive digital drawing application on photographic images located within an iPad and how the resulting images were conceptualised and created.
- Description: Masters by Research
Tropical cyclone tracks in CMIP5 models : statistical assessment and future projections
- Authors: Bell, Samuel
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Tropical cyclones (TCs) can have devastating social and economic impacts on coastal communities situated all around the globe. The impact of anthropogenic induced climate change on TC activity has attracted widespread scientific interest over the past decade, resulting in the development of a variety of approaches for TC projection in climate models. However, many uncertainties remain, including those associated with the TC detection algorithm and climate model inter-dependencies that impact projection results. This thesis seeks to address these uncertainties, as well as filling several knowledge gaps in the literature such as limited TC projection studies in the Southern Hemisphere and a global need for regional-scale TC track density projections. The independent TC detection and tracking algorithm utilised in this thesis is first evaluated to determine if it can simulate a realistic TC track climatology in reanalysis data. By way of cluster analysis, model-detected and observed TC tracks are compared and objective criteria for a consistent “TC track” definition are established. Regional-scale TC track projections are then examined in each TC basin around the globe. The exact methodology of cluster analysis in each basin is slightly modified to accommodate basin-scale differences in track climatology but generally follows a cluster assessment of TC tracks in observations, historical climate simulations and future climate projections using results from the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Regional impacts of the El Niño Southern Oscillation (ENSO) on TC tracks are also examined in current- and future-climates. Projection results are found to be supportive of existing studies, especially in the North Pacific and the Southern Hemisphere. Isolation of TC tracks into clusters indicated that the regional dominance of ENSO is well simulated by the CMIP5 models. Several regional changes in TC activity are noted and attributed to projected changes in the large-scale environment, and changes in ENSO-specific conditions.
- Description: Doctor of Philosophy
- Authors: Bell, Samuel
- Date: 2019
- Type: Text , Thesis , PhD
- Full Text:
- Description: Tropical cyclones (TCs) can have devastating social and economic impacts on coastal communities situated all around the globe. The impact of anthropogenic induced climate change on TC activity has attracted widespread scientific interest over the past decade, resulting in the development of a variety of approaches for TC projection in climate models. However, many uncertainties remain, including those associated with the TC detection algorithm and climate model inter-dependencies that impact projection results. This thesis seeks to address these uncertainties, as well as filling several knowledge gaps in the literature such as limited TC projection studies in the Southern Hemisphere and a global need for regional-scale TC track density projections. The independent TC detection and tracking algorithm utilised in this thesis is first evaluated to determine if it can simulate a realistic TC track climatology in reanalysis data. By way of cluster analysis, model-detected and observed TC tracks are compared and objective criteria for a consistent “TC track” definition are established. Regional-scale TC track projections are then examined in each TC basin around the globe. The exact methodology of cluster analysis in each basin is slightly modified to accommodate basin-scale differences in track climatology but generally follows a cluster assessment of TC tracks in observations, historical climate simulations and future climate projections using results from the Coupled Model Intercomparison Project Phase 5 (CMIP5) models. Regional impacts of the El Niño Southern Oscillation (ENSO) on TC tracks are also examined in current- and future-climates. Projection results are found to be supportive of existing studies, especially in the North Pacific and the Southern Hemisphere. Isolation of TC tracks into clusters indicated that the regional dominance of ENSO is well simulated by the CMIP5 models. Several regional changes in TC activity are noted and attributed to projected changes in the large-scale environment, and changes in ENSO-specific conditions.
- Description: Doctor of Philosophy
"Beyond home and sex?" : Gender and sexuality in Elizabeth Moon's
- Authors: O'Sullivan, Jennifer
- Date: 2018
- Type: Text , Thesis , Masters
- Full Text:
- Description: Historically, fantasy fiction has tended to present sexuality and gender in a conservative light. Contemporary authors in this genre have the opportunity to imagine worlds in which they can critique these norms and offer new and subversive alternatives. Elizabeth Moon’s work has been seen by some readers and critics (Mains, et al, Bach) to challenge conservative gender roles, and while in some areas this is evident, a critical reading of her Paksworld series through a feminist lens reveals that her work is still largely restricted by normative notions of gender and heteronormative contexts and ideals. In this thesis I argue that while Moon’s female characters are allowed a certain amount of autonomy, they are still often repressed by those around them, silenced, or subject to male dominance and/or sexual violence. Those women in the novels who achieve a position of social, political or spiritual power are forced to make choices between roles: for example, between being a warrior and a mother, and are not allowed to ‘have it all’. Moon does subvert some familiar feminine tropes – her fantasy princesses for example avoid being married against their will, and her female warriors are more complex than simply being ‘sheroes’. Utilising masculinities and disability theory, I also analyse Moon’s treatment of men and masculinity. While Moon presents several familiar male fantasy tropes, she also portrays some surprisingly subversive men. These men are forced to reimagine and reinterpret their own masculine identities by having to confront ageing, disability, mutilation and loss of personal power while negotiating traditionally masculine homo-social environments. Finally, I argue that Moon’s presentation of sexuality in the Paksworld series is problematic and conservative in that very few of her characters are having pleasurable, consensual sex, especially not outside traditional marriage structures. Furthermore, the Paksworld series is largely heteronormative, with same-sex desire identified predominantly with a character who is presented as an antagonist to Paks. Paks herself is asexual, and I argue that Moon uses this as a way to avoid dealing with the issue of female sexual desire rather than an opportunity to explore asexuality as a valid sexual preference or identity. Overall, I argue that despite some subversive elements, Moon’s characters are still largely restricted by conservative expectations of genre, culture, gender and sexuality.
- Description: Masters by Research
- Authors: O'Sullivan, Jennifer
- Date: 2018
- Type: Text , Thesis , Masters
- Full Text:
- Description: Historically, fantasy fiction has tended to present sexuality and gender in a conservative light. Contemporary authors in this genre have the opportunity to imagine worlds in which they can critique these norms and offer new and subversive alternatives. Elizabeth Moon’s work has been seen by some readers and critics (Mains, et al, Bach) to challenge conservative gender roles, and while in some areas this is evident, a critical reading of her Paksworld series through a feminist lens reveals that her work is still largely restricted by normative notions of gender and heteronormative contexts and ideals. In this thesis I argue that while Moon’s female characters are allowed a certain amount of autonomy, they are still often repressed by those around them, silenced, or subject to male dominance and/or sexual violence. Those women in the novels who achieve a position of social, political or spiritual power are forced to make choices between roles: for example, between being a warrior and a mother, and are not allowed to ‘have it all’. Moon does subvert some familiar feminine tropes – her fantasy princesses for example avoid being married against their will, and her female warriors are more complex than simply being ‘sheroes’. Utilising masculinities and disability theory, I also analyse Moon’s treatment of men and masculinity. While Moon presents several familiar male fantasy tropes, she also portrays some surprisingly subversive men. These men are forced to reimagine and reinterpret their own masculine identities by having to confront ageing, disability, mutilation and loss of personal power while negotiating traditionally masculine homo-social environments. Finally, I argue that Moon’s presentation of sexuality in the Paksworld series is problematic and conservative in that very few of her characters are having pleasurable, consensual sex, especially not outside traditional marriage structures. Furthermore, the Paksworld series is largely heteronormative, with same-sex desire identified predominantly with a character who is presented as an antagonist to Paks. Paks herself is asexual, and I argue that Moon uses this as a way to avoid dealing with the issue of female sexual desire rather than an opportunity to explore asexuality as a valid sexual preference or identity. Overall, I argue that despite some subversive elements, Moon’s characters are still largely restricted by conservative expectations of genre, culture, gender and sexuality.
- Description: Masters by Research
100 years of annual reporting by Australian Red Cross : Accountability amidst wars, disasters and loss of life
- Authors: Langton, Jonathan
- Date: 2018
- Type: Text , Thesis , PhD
- Full Text:
- Description: Purpose: This critical interpretive and historical case study of Australian Red Cross extends from the organisation’s beginning in 1914 through to the present day. The overarching purpose is to reveal and analyse the annual reporting practices of one of Australia’s oldest and most important humanitarian organisations in the discharge of accountability over the course of a century. Design/methodology/approach: A Political Economy of Accounting theoretical framework guides the content analysis and interpretation of findings. Background: While the review of literature acknowledges the annual report as a crucial element in the discharge of accountability, studies investigating the evolution of annual reports of International nongovernmental development and humanitarian aid organisations (INGDHOs) over extended periods of time appear to be absent from the literature. Findings: The annual reports were found to be responsive to the changing social, political, economic and institutional environment, casting doubt on any claims to objectivity in organisational management’s disclosures, including assertions regarding unadulterated adherence to its Fundamental Principles. Furthermore, sources of pressure from the wider environmental context impacted upon the development of accountability regimes and shaped the way in which organisational management reported to stakeholders. These regimes evidence the alignment of mission preservation and emotive disclosures with strategic priorities. Implications: This study extends understandings of how INGDHOs discharge accountability through annual reporting practices. It provides a more holistic framework for understanding the role of accountability in organisational management reporting, the development of accountability regimes and the implications for organisational and social functioning. Originality/value (significance): The contribution is distinctive not only for the context and extensive period covered, but also for the significant institutional setting of Australian Red Cross – encompassing deep social, political, economic and institutional changes. This adds to the extant literature and provides significant insights into the contested interplay between annual reporting practices and accountability regimes.
- Description: Doctor of Philosophy
- Authors: Langton, Jonathan
- Date: 2018
- Type: Text , Thesis , PhD
- Full Text:
- Description: Purpose: This critical interpretive and historical case study of Australian Red Cross extends from the organisation’s beginning in 1914 through to the present day. The overarching purpose is to reveal and analyse the annual reporting practices of one of Australia’s oldest and most important humanitarian organisations in the discharge of accountability over the course of a century. Design/methodology/approach: A Political Economy of Accounting theoretical framework guides the content analysis and interpretation of findings. Background: While the review of literature acknowledges the annual report as a crucial element in the discharge of accountability, studies investigating the evolution of annual reports of International nongovernmental development and humanitarian aid organisations (INGDHOs) over extended periods of time appear to be absent from the literature. Findings: The annual reports were found to be responsive to the changing social, political, economic and institutional environment, casting doubt on any claims to objectivity in organisational management’s disclosures, including assertions regarding unadulterated adherence to its Fundamental Principles. Furthermore, sources of pressure from the wider environmental context impacted upon the development of accountability regimes and shaped the way in which organisational management reported to stakeholders. These regimes evidence the alignment of mission preservation and emotive disclosures with strategic priorities. Implications: This study extends understandings of how INGDHOs discharge accountability through annual reporting practices. It provides a more holistic framework for understanding the role of accountability in organisational management reporting, the development of accountability regimes and the implications for organisational and social functioning. Originality/value (significance): The contribution is distinctive not only for the context and extensive period covered, but also for the significant institutional setting of Australian Red Cross – encompassing deep social, political, economic and institutional changes. This adds to the extant literature and provides significant insights into the contested interplay between annual reporting practices and accountability regimes.
- Description: Doctor of Philosophy
A comparative analysis of domestic violence against women in Australia and Bangladesh : government policies, legislation and organisational responses
- Authors: Rahman, Nasrin
- Date: 2018
- Type: Text , Thesis , PhD
- Full Text:
- Description: This is a comparative study of Domestic Violence (DV) between Australia (Victoria) and Bangladesh. It examined the interrelationship between factors which contribute to DV, government policies and legislation developed to deal with DV, and organisational responders (police and DV Crisis Support Services) implementing strategies and remedies in the policies and legislation. A comparative country case study strategy was adopted utilising triangulation of methods of data collection including an analysis of the countries’ respective policies and legislation and conducting in-depth interviews with key responder personnel. The conceptual framework identified policies and legislation as Steering Media, which influenced a society’s beliefs embedded in the Lifeworld, and which guided the actions of responders to DV in the two different countries’ Systems. Differences and similarities were found between the two countries. The main common factor was the identification of gender inequality as an underlying factor causing DV. Some social and cultural factors exist in both countries such as poverty. Some factors were specific to Australia, such as the consumption of alcohol; and in Bangladesh, such as dowry and dependency on men. Of significance is that gender equality is enshrined in the Bangladeshi Constitution, while Australia relies on legislation that could potentially be changed to disadvantage women. Differences revealed include identification of victims and perpetrators, with Bangladesh specifically naming women and children as victims but never the perpetrator and Australia (Victoria) naming any family member as victim or perpetrator. Also, responders deal with DV victims and perpetrators differently according to the policies and legislation of both countries. This research has implications for both theory and practice in both countries. The findings have potential to contribute to changes in policy and legislation related to DV as well as in the practice level by responders across both countries, learning from each other in the process.
- Description: Doctor of Philosophy
- Authors: Rahman, Nasrin
- Date: 2018
- Type: Text , Thesis , PhD
- Full Text:
- Description: This is a comparative study of Domestic Violence (DV) between Australia (Victoria) and Bangladesh. It examined the interrelationship between factors which contribute to DV, government policies and legislation developed to deal with DV, and organisational responders (police and DV Crisis Support Services) implementing strategies and remedies in the policies and legislation. A comparative country case study strategy was adopted utilising triangulation of methods of data collection including an analysis of the countries’ respective policies and legislation and conducting in-depth interviews with key responder personnel. The conceptual framework identified policies and legislation as Steering Media, which influenced a society’s beliefs embedded in the Lifeworld, and which guided the actions of responders to DV in the two different countries’ Systems. Differences and similarities were found between the two countries. The main common factor was the identification of gender inequality as an underlying factor causing DV. Some social and cultural factors exist in both countries such as poverty. Some factors were specific to Australia, such as the consumption of alcohol; and in Bangladesh, such as dowry and dependency on men. Of significance is that gender equality is enshrined in the Bangladeshi Constitution, while Australia relies on legislation that could potentially be changed to disadvantage women. Differences revealed include identification of victims and perpetrators, with Bangladesh specifically naming women and children as victims but never the perpetrator and Australia (Victoria) naming any family member as victim or perpetrator. Also, responders deal with DV victims and perpetrators differently according to the policies and legislation of both countries. This research has implications for both theory and practice in both countries. The findings have potential to contribute to changes in policy and legislation related to DV as well as in the practice level by responders across both countries, learning from each other in the process.
- Description: Doctor of Philosophy
A conceptual framework for a theory of liquidity
- Authors: Culham, James
- Date: 2018
- Type: Text , Thesis , Masters , PhD
- Full Text:
- Description: This study contributes to the understanding of liquidity in two ways. First, it considers the multifaceted nature of liquidity and its relationship with money. Second, it constructs a conceptual framework for a theory of liquidity. The first contribution is achieved by clarifying and categorising the various forms of liquidity to identify those overlooked by the existing literature. The second contribution consists of a realist critique of the literature on liquidity and money to highlight the strengths and weaknesses of each theoretical approach. The study reflects on the attempts to analyse liquidity using moneyless models of perfect barter with the assumption that every commodity exhibits perfect saleability; an assumption that removes any need for a medium of exchange and, moreover, crowds out all other forms of liquidity. It is concluded that, because liquidity is a social and monetary phenomenon, it cannot be analysed with models populated by a representative agent consuming a single commodity. Furthermore, this conclusion is not altered by the introduction of ‘financial frictions’, which are fundamentally at odds with the nature of money. Instead, the clarification of the nature of liquidity forms the basis for an interpretation of Keynes’s theory of liquidity preference that emphasises its reliance on liquidity in general, not money in particular. The study introduces the terms redemption liquidity and exchange liquidity to explain the trade-off that underpins the theory of liquidity preference. Properly interpreted, the theory of liquidity preference can then address many of the deficiencies prevalent in the dominant theories of the rate of interest. The study therefore has implications for monetary policy and asset pricing.
- Description: Doctor of Philosophy
- Authors: Culham, James
- Date: 2018
- Type: Text , Thesis , Masters , PhD
- Full Text:
- Description: This study contributes to the understanding of liquidity in two ways. First, it considers the multifaceted nature of liquidity and its relationship with money. Second, it constructs a conceptual framework for a theory of liquidity. The first contribution is achieved by clarifying and categorising the various forms of liquidity to identify those overlooked by the existing literature. The second contribution consists of a realist critique of the literature on liquidity and money to highlight the strengths and weaknesses of each theoretical approach. The study reflects on the attempts to analyse liquidity using moneyless models of perfect barter with the assumption that every commodity exhibits perfect saleability; an assumption that removes any need for a medium of exchange and, moreover, crowds out all other forms of liquidity. It is concluded that, because liquidity is a social and monetary phenomenon, it cannot be analysed with models populated by a representative agent consuming a single commodity. Furthermore, this conclusion is not altered by the introduction of ‘financial frictions’, which are fundamentally at odds with the nature of money. Instead, the clarification of the nature of liquidity forms the basis for an interpretation of Keynes’s theory of liquidity preference that emphasises its reliance on liquidity in general, not money in particular. The study introduces the terms redemption liquidity and exchange liquidity to explain the trade-off that underpins the theory of liquidity preference. Properly interpreted, the theory of liquidity preference can then address many of the deficiencies prevalent in the dominant theories of the rate of interest. The study therefore has implications for monetary policy and asset pricing.
- Description: Doctor of Philosophy
A new perceptual dissimilarity measure for image retrieval and clustering
- Authors: Shojanazeri, Hamid
- Date: 2018
- Type: Text , Thesis , PhD
- Full Text:
- Description: Image retrieval and clustering are two important tools for analysing and organising images. Dissimilarity measure is central to both image retrieval and clustering. The performance of image retrieval and clustering algorithms depends on the effectiveness of the dissimilarity measure. ‘Minkowski’ distance, or more specifically, ‘Euclidean’ distance, is the most widely used dissimilarity measure in image retrieval and clustering. Euclidean distance depends only on the geometric position of two data instances in the feature space and completely ignores the data distribution. However, data distribution has an effect on human perception. The argument that two data instances in a dense area are more perceptually dissimilar than the same two instances in a sparser area, is proposed by psychologists. Based on this idea, a dissimilarity measure called, ‘mp’, has been proposed to address Euclidean distance’s limitation of ignoring the data distribution. Here, mp relies on data distribution to calculate the dissimilarity between two instances. As prescribed in mp, higher data mass between two data instances implies higher dissimilarity, and vice versa. mp relies only on data distribution and completely ignores the geometric distance in its calculations. In the aggregation of dissimilarities between two instances over all the dimensions in feature space, both Euclidean distance and mp give same priority to all the dimensions. This may result in a situation that the final dissimilarity between two data instances is determined by a few dimensions of feature vectors with relatively much higher values. As a result, the dissimilarity derived may not align well with human perception. The need to address the limitations of Minkowski distance measures, along with the importance of a dissimilarity measure that considers both geometric distance and the perceptual effect of data distribution in measuring dissimilarity between images motivated this thesis. It studies the performance of mp for image retrieval. It investigates a new dissimilarity measure that combines both Euclidean distance and data distribution. In addition to these, it studies the performance of such a dissimilarity measure for image retrieval and clustering. Our performance study of mp for image retrieval shows that relying only on data distribution to measure the dissimilarity results in some situations, where the mp’s measurement is contrary to human perception. This thesis introduces a new dissimilarity measure called, perceptual dissimilarity measure (PDM). PDM considers the perceptual effect of data distribution in combination with Euclidean distance. PDM has two variants, PDM1 and PDM2. PDM1 focuses on improving mp by weighting it using Euclidean distance in situations where mp may not retrieve accurate results. PDM2 considers the effect of data distribution on the perceived dissimilarity measured by Euclidean distance. PDM2 proposes a weighting system for Euclidean distance using a logarithmic transform of data mass. The proposed PDM variants have been used as alternatives to Euclidean distance and mp to improve the accuracy in image retrieval. Our results show that PDM2 has consistently performed the best, compared to Euclidean distance, mp and PDM1. PDM1’s performance was not consistent, although it has performed better than mp in all the experiments, but it could not outperform Euclidean distance in some cases. Following the promising results of PDM2 in image retrieval, we have studied its performance for image clustering. k-means is the most widely used clustering algorithm in scientific and industrial applications. k-medoids is the closest clustering algorithm to k-means. Unlike k-means which works only with Euclidean distance, k-medoids gives the option to choose the arbitrary dissimilarity measure. We have used Euclidean distance, mp and PDM2 as the dissimilarity measure in k-medoids and compared the results with k-means. Our clustering results show that PDM2 has perfromed overally the best. This confirms our retrieval results and identifies PDM2 as a suitable dissimilarity measure for image retrieval and clustering.
- Description: Doctor of Philosophy
- Authors: Shojanazeri, Hamid
- Date: 2018
- Type: Text , Thesis , PhD
- Full Text:
- Description: Image retrieval and clustering are two important tools for analysing and organising images. Dissimilarity measure is central to both image retrieval and clustering. The performance of image retrieval and clustering algorithms depends on the effectiveness of the dissimilarity measure. ‘Minkowski’ distance, or more specifically, ‘Euclidean’ distance, is the most widely used dissimilarity measure in image retrieval and clustering. Euclidean distance depends only on the geometric position of two data instances in the feature space and completely ignores the data distribution. However, data distribution has an effect on human perception. The argument that two data instances in a dense area are more perceptually dissimilar than the same two instances in a sparser area, is proposed by psychologists. Based on this idea, a dissimilarity measure called, ‘mp’, has been proposed to address Euclidean distance’s limitation of ignoring the data distribution. Here, mp relies on data distribution to calculate the dissimilarity between two instances. As prescribed in mp, higher data mass between two data instances implies higher dissimilarity, and vice versa. mp relies only on data distribution and completely ignores the geometric distance in its calculations. In the aggregation of dissimilarities between two instances over all the dimensions in feature space, both Euclidean distance and mp give same priority to all the dimensions. This may result in a situation that the final dissimilarity between two data instances is determined by a few dimensions of feature vectors with relatively much higher values. As a result, the dissimilarity derived may not align well with human perception. The need to address the limitations of Minkowski distance measures, along with the importance of a dissimilarity measure that considers both geometric distance and the perceptual effect of data distribution in measuring dissimilarity between images motivated this thesis. It studies the performance of mp for image retrieval. It investigates a new dissimilarity measure that combines both Euclidean distance and data distribution. In addition to these, it studies the performance of such a dissimilarity measure for image retrieval and clustering. Our performance study of mp for image retrieval shows that relying only on data distribution to measure the dissimilarity results in some situations, where the mp’s measurement is contrary to human perception. This thesis introduces a new dissimilarity measure called, perceptual dissimilarity measure (PDM). PDM considers the perceptual effect of data distribution in combination with Euclidean distance. PDM has two variants, PDM1 and PDM2. PDM1 focuses on improving mp by weighting it using Euclidean distance in situations where mp may not retrieve accurate results. PDM2 considers the effect of data distribution on the perceived dissimilarity measured by Euclidean distance. PDM2 proposes a weighting system for Euclidean distance using a logarithmic transform of data mass. The proposed PDM variants have been used as alternatives to Euclidean distance and mp to improve the accuracy in image retrieval. Our results show that PDM2 has consistently performed the best, compared to Euclidean distance, mp and PDM1. PDM1’s performance was not consistent, although it has performed better than mp in all the experiments, but it could not outperform Euclidean distance in some cases. Following the promising results of PDM2 in image retrieval, we have studied its performance for image clustering. k-means is the most widely used clustering algorithm in scientific and industrial applications. k-medoids is the closest clustering algorithm to k-means. Unlike k-means which works only with Euclidean distance, k-medoids gives the option to choose the arbitrary dissimilarity measure. We have used Euclidean distance, mp and PDM2 as the dissimilarity measure in k-medoids and compared the results with k-means. Our clustering results show that PDM2 has perfromed overally the best. This confirms our retrieval results and identifies PDM2 as a suitable dissimilarity measure for image retrieval and clustering.
- Description: Doctor of Philosophy
Abnormalities in T cell lineages from patients with Langerhans cell histiocytosis
- Authors: Mitchell, Jenée
- Date: 2018
- Type: Text , Thesis , PhD
- Full Text:
- Description: Langerhans cell histiocytosis (LCH) is a rare inflammatory disease characterised by lesions containing CD1a+ myeloid lineage ‘LCH’ cells. Other immune cells such as T cells are also present within LCH lesions and the cytokine milieu suggests T cell activation. T cells have an established role in regulating cellular immunity and there is already evidence that multiple T cell lineages are enriched in LCH lesions, implying that they may have a role in LCH pathogenesis. Foxp3+ regulatory T cells (Tregs) and the immune suppressive cytokine, transforming growth factor beta (TGF-
- Description: Doctor of Philosophy
- Authors: Mitchell, Jenée
- Date: 2018
- Type: Text , Thesis , PhD
- Full Text:
- Description: Langerhans cell histiocytosis (LCH) is a rare inflammatory disease characterised by lesions containing CD1a+ myeloid lineage ‘LCH’ cells. Other immune cells such as T cells are also present within LCH lesions and the cytokine milieu suggests T cell activation. T cells have an established role in regulating cellular immunity and there is already evidence that multiple T cell lineages are enriched in LCH lesions, implying that they may have a role in LCH pathogenesis. Foxp3+ regulatory T cells (Tregs) and the immune suppressive cytokine, transforming growth factor beta (TGF-
- Description: Doctor of Philosophy