UQ Theses Collection (RHD) - UQ staff and students only - UQ eSpace

The role of summer dormancy in improving survival of temperate perennial pasture grasses in drought-prone environments

Norton, Mark Roger — 2008-11-21T00:00:00Z

The poor survival of perennial pasture grasses is a major constraint to agricultural systems where summers are characterised by long, severe droughts and high temperatures. The search for grasses with superior tolerance to these conditions has resulted in a re-awakening of interest in the summer dormancy trait leading to the recent release of several summer dormant cultivars. This has led to renewed questioning about the nature of summer dormancy particularly as the definition of the trait is unclear. Therefore, this research has aimed to strengthen understanding of summer dormancy in the pasture grasses Dactylis glomerata L. (cocksfoot), Festuca arundinacea Schreb. (tall fescue) and Phalaris aquatica L. (phalaris) by studying two cultivars contrasting in the expression of summer dormancy from each species. A range of field trials in the south of France aimed to identify key physiological mechanisms whereby summer dormancy enhances survival over long, dry summers by concentrating on the effects of different levels of summer water supply and plant maturity. Field trials in that region also compared and evaluated several methods to measure the intensity of summer dormancy and developed a new method based on herbage production from irrigated summer culture. Growth chamber trials with small pots studied the relationship between temperature and the expression of summer dormancy by comparing the growth response to a range of temperatures of two cohorts of plants contrasting in exposure to conditions aimed to induce summer dormancy. Finally, winter research conducted in pots in the glasshouse subjected plants to drying cycles to study dehydration tolerance and avoidance and related these to the expression of the summer dormancy which had been observed in the summer field studies. The component mechanisms of summer dormancy were clearly expressed under full summer irrigation by reproductive plants which had been vernalised and although present in younger, spring-sown plants they were approx. 40% less intense while the tall fescue cv only expressed dormancy if subjected to prior drought. Expression began in late spring/early summer and included growth cessation and herbage senescence resulting in substantially less summer evapotranspiration in the dormant tall fescue and cocksfoot swards compared to their summer active counterparts. The dormant cocksfoot under drought dehydrated to -6.7 MPa and even under irrigation dehydration to -3 MPa occurred . In contrast, under irrigation the dormant tall fescue and phalaris cvs remained hydrated. Dehydrin expression increased in all cvs as water deficit intensified but while expression declined after a storm in the non-dormant cvs (in response to increased water status), levels remained uniformly high in the three dormant cvs. The summer dormant tall fescue maintained full sward cover after summer droughts of 116 and 144 days whereas cover in the summer active cv fell by approx. 25%. Similar sward loss (22%) occurred in a summer active cocksfoot, in contrast to the summer dormant cv after a 144 day drought. No survival advantage for the summer dormant cv was measured in phalaris although this seemed to be due to unique field trial site characteristics. Five methods for summer dormancy measurement varying according to summer water availability, i.e., full irrigation, mid-summer storm and complete drought, and assessment method, viz., herbage production measurement or visual estimation of herbage senescence, were compared and evaluated. A method using the herbage harvested from irrigated summer culture was developed. Summer dormancy is best measured under non-limiting moisture, because assessing the trait under complete drought can result in false scores, e.g. Medly cocksfoot was moderately dormant under drought (6/10), but non-dormant under full summer irrigation or after a storm (1-2/10). Dormancy was scored equally well by measuring herbage production or by visually assessing the level of herbage senescence. The examination of the effect of temperature on summer dormancy questioned whether dormancy is independent of temperature or is simply a decline in growth in response to high summer temperatures. In cocksfoot the decline associated with summer dormancy (approx. 100%) was independent from any which occurred as a result of high temperatures. In tall fescue, despite indications that dormancy was a separate effect it was not possible to definitively separate the effects of rising temperature from prior dormancy induction suggesting the need for further research. Inconsistent and inconclusive results occurred in phalaris suggesting that small pot culture is inappropriate for studying dormancy in this species. Subjecting plants to drying cycles in a winter glasshouse environment demonstrated that dehydration tolerance, dehydration avoidance and summer dormancy are separate responses able to be independently expressed. In cocksfoot and tall fescue two highly dehydration-avoiding cvs also expressed high levels of dormancy in summer as reproductive plants although a summer active cocksfoot was also highly dehydration-avoiding. In contrast, the highly summer dormant phalaris cvs showed no greater levels of dehydration avoidance/tolerance than much less dormant cvs. The research has identified key mechanisms of drought survival as being component, defining characteristics of summer dormancy and has also demonstrated robust screening methods to extend utilisation of the trait in plant improvement.

The role of suppressors of cytokine signalling (SOCS) in prolactin action

Tam, Sau Ping — 2007-08-24T18:20:17Z

The role of synapse formation on motoneuron survival during embryonic development

Banks, Glen B. — 2011-08-09T00:00:00Z

The role of the Activator Protein-2 transcription factor family in human skin and its appendages

Popa, Claudia — 2007-08-24T18:10:45Z

The Role of the Internet in the Lives of People with Traumatic Brain Injury

Jennifer Egan — 2010-06-17T00:00:00Z

Psychosocial factors represent complex and enduring challenges for people with a traumatic brain injury (TBI), their families and health and rehabilitation systems, particularly in relation to social isolation, change/loss of role and identity issues. Traditional rehabilitation approaches to psychosocial issues target cognitive rehabilitation and psychological adjustment of the individual with a TBI, which reflect the medical model of health. However, the International Classification of Functioning, Disability and Health (ICF) ushers a new era in TBI research and practice, which advances the conceptualisation of disability, to include the impact of environmental factors. The ICF identifies the Internet as one such environmental factor, which has the potential to facilitate or impede social participation of people with a disability. Empirical studies suggest the potential of the Internet to empower people with disabilities, via opportunities for social connection; social support; social role participation and identity experimentation. However, research has focused on people with sensory, physical, and mental health issues, with little known of the potential of the Internet for people with a TBI. This area of deficit warrants investigation, in view of the potential of the Internet to address many dimensions of psychosocial concern following TBI. This study explores the role of the Internet in the lives of people with a TBI, with a focus on the potential of the Internet to influence psychosocial recovery. Psychosocial recovery is conceptualised as the reconstruction of a positive identity, as found in subjective accounts of people with a TBI (Lewington, 1996), and strongly supported in the mental health consumer literature. Using a social constructionist approach, this study explores how people with a TBI use the Internet and how they make meaning of their Internet experience. This approach acknowledges the socially situated nature of Internet use and validates the subjective accounts of people with a TBI, whose perspectives are underrepresented in the rehabilitation literature. This study also trials the method of email-facilitated qualitative interviewing, to address face-to-face interviewing barriers, relating to cognitive-linguistic impairments (Lloyd, Gatherer, & Kalsy, 2006; Paterson & Scott-Findley, 2002). Thus, the Internet is the focus of the enquiry and the mediator of the method. The findings highlight the positive potential of the Internet to facilitate social participation for people with a TBI. Participants reported that features such as asynchronicity, reduced cues and anonymity made the Internet an accessible and usable technology, for social connection; social support; social role participation and identity reconstruction. A major theme emerging from the data was control of self, which this study conceptually linked to identity reconstruction and psychosocial recovery. Findings allayed concerns regarding the negative potential of the Internet to increase social isolation of vulnerable people, as participants regarded face-to-face relationships as more fulfilling than online friendships, supporting classic communication theories (Rice, 1987; Rice & Love, 1987), which propose that the Internet is a less personal medium than face-to-face communication, due to the feature of reduced cues. The findings of the method indicated that email facilitated qualitative interviewing addressed face-to-face interviewing barriers related to cognitive linguistic impairments; mobility factors; chronic health issues and environmental stimuli. Most participants indicated that asynchronicity, reduced cues, and anonymity facilitated control of communication, cognition and identity, thus enabling interview participation. The method had also advantages for the researcher, including time for reflection and the ability to yield richer data than in face-to-face contexts. However, the method was resource intensive, requiring information technology proficiency, familiarly with the impact of cognitive-linguistic impairments in online contexts and counselling experience. In addition, ethical guidelines required the involvement of a support person for the emotional protection of participants. This study makes two contributions to knowledge. One contribution relates to the potential of the Internet as an ICF environmental factor to address long-term psychosocial concerns, in addition to positively influencing psychosocial recovery from TBI, as reported by participants. This study contributes to a new era of research, which considers the impact of environmental factors on the experience of TBI, as framed by the ICF. The second contribution relates to the method of email facilitated qualitative interviewing, which advances knowledge of interviewing barriers for people with a TBI and addresses calls for innovative methods with this population. The findings of the method bring into question long held assumptions about the capacity of people with a TBI to participate in research and have implications for research design in qualitative and quantitative methodologies.

The role of the judge in civil trials : a comparison of German and Australian processes

Gregory, Shannon Therese — 2012-10-10T13:31:21Z

The role of the national government in facilitating innovation within the tourism industry: a case from Norway

Mei, Xiang Ying — 2012-09-05T20:35:10Z

THE ROLE OF THE PLANT CELL WALL ON THE BIOACCESSIBILITY AND BIOAVAILABILITY OF ANTHOCYANINS AND PHENOLIC ACIDS RELEASED FROM FRUITS AND VEGETABLES.

Anneline Padayachee — 2012-06-28T00:00:00Z

Fruits and vegetables are well known sources of vitamins, minerals and fibre as well as polyphenolic compounds and other phytonutrients. Extensive research into the chemoprotective benefits of plant-based foods has found that such compounds and their metabolites have antioxidant, anti-inflammatory and/or anti-carcinogenic properties. Whilst the health benefits associated with high dietary intake of fruit and vegetable polyphenols is a well researched field, the role of the plant cell wall on the bioaccessibility of these compounds is not. Polyphenolic and other nutrient compounds are located within the vacuole of plant cells surrounded by a lipid membrane and thereby separated from the plant cell wall which encapsulates the cell. In order for polyphenols and other nutrients to be bioavailable (i.e. absorbed during digestion through the gastrointestinal tract), they must first become bioaccessible (i.e. released from the plant cell ready to be absorbed by the body). In order for nutrients to be bioaccessible, the plant cell wall needs to be breached with the consequent possibility of binding between nutrients and plant cell walls. This thesis explores the nature of interactions between plant cell walls and two important classes of polyphenolic phytonutrients, anthocyanins and phenolic acids. The main structural constituent of the fruit and vegetable cell wall is cellulose, which is surrounded by a matrix of pectin and hemicelluloses, and at times lignin. Lignin directly affects the textural and palatability qualities of plant foods, and is generally not present in large amounts in fruits and vegetables. Cellulose fibres are tough and insoluble, and hence able to resist substantial force and provide support to the plant cells, whilst pectin increases the flexibility through formation of a co-extensive network with the rigid cellulose fibre network. The degree of methyl esterification (DE) of carboxyl groups is commonly used to differentiate pectins and to control network formation. The role of cell walls in polyphenol bioaccessibility has not been researched extensively. Rupture of the cell wall during mastication or processing (e.g. pureeing or juicing) results in polyphenols being released from the cell vacuole with consequent contact with cell walls for the first time, with the potential for binding interactions to occur. The human upper gastrointestinal tract (stomach and small intestine (S.I.) is unable to digest plant cell walls. Therefore if polyphenols bound to plant cell walls at the point of ingestion are not released from the cell wall material during transit through the gastric and small intestinal digestive phases, they will be carried by the cell walls to the large intestine where they may be released by bacterial fermentation of cell wall polymers and potentially further metabolised by bacteria before being either absorbed or excreted. This research fills several major gaps in current knowledge by: 1) identifying potential mechanisms for polyphenol-plant cell wall interactions; 2) assessing the bioaccessibility of polyphenols in a real vegetable system; and 3) examining the release of plant cell wall-bound polyphenols during gastric and S.I. digestion and the potential delivery of polyphenols to the colon. The extent of anthocyanin and phenolic acid interaction with cell wall components was investigated by monitoring the rate of polyphenol depletion from diluted purple carrot juice concentrate in the presence of pure cellulose or cellulose-pectin composites containing either low DE or high DE pectins, produced by the bacterium Gluconacetobacter xylinus. Binding of anthocyanins to plant cell wall components seems to be a 2-stage process with initially (1 hour) a limited amount (13-18%) of anthocyanins bound to the surface of the cellulose or cellulose-pectin composite. Whilst anthocyanins bound to both cellulose and pectin, more were bound to pectin. With prolonged exposure (7 days) to cell wall material, a gradual increase in anthocyanin binding occurred with approximately 35% binding to cellulose and the high DE composite and up to 80% binding to the low DE composite. This may be due to anthocyanins stacking on top of a base layer. Support for localised deposition of anthocyanins was found from confocal microscopy which showed apparent local high concentrations of anthocyanins alongside regions with much less, if any, bound anthocyanins. There does not seem to be molecular selectivity as depletion from solution of individual anthocyanin molecules is similar throughout the binding process. Phenolic acid depletion from solution in the presence of model cell walls also occurred. However unlike anthocyanins, more phenolic acids were bound to the pure cellulose initially than to the cellulose-pectin composites. Phenolic acid depletion was rapid, with approximately 20% phenolic acids binding to cell wall components within the first hour. This gradually increased to approximately 35% (low DE composite) and 50% (high DE composite and pure cellulose) over 14 days contact time. Additionally phenolic acid depletion from different concentrations of diluted purple carrot juice concentrate was similar indicating that cell walls may have a limited saturation level for binding phenolic acids. Conversely, doubling the concentration of free anthocyanins available led to at least twice as much binding with cell wall components. This indicates that whilst anthocyanin binding is slow, it may not be limited by available binding sites. Extrapolation of data from these model systems to carrot puree suggests that significant amounts of anthocyanins and phenolic acids could bind to the plant cell wall, potentially restricting their bioavailability in the S.I. In order to ascertain the potential extent of polyphenol delivery to the large intestine via plant fibre in a real food system, polyphenols bound to cell wall material in a black carrot puree were subjected to simulated gastric and small intestinal digestion. It was found that the majority of available hydrophilic polyphenols derived from black carrots bound to the PCW matter with only ~ 36 % of the total phenolic acids (~ 1.2 mg/g puree) and 30 % of anthocyanins (1.3 mg/g puree) in the black carrot puree being released into the liquid phase. Approximately 30 % of the bound phenolic acids and anthocyanins could be extracted with acidified methanol. However, only <5 % of anthocyanins and phenolic acids were released during simulated gastric and small intestinal digestion. This is in agreement with results from the model cell wall system where the majority of bound polyphenols remained bound after simulated gastric and small intestinal digestion indicating that the binding mechanism between polyphenols and cell wall components is sufficiently strong to resist pH changes during the digestive process. This may be due to a 3-phase mechanism with initial random binding of anthocyanins and phenolic acids to cellulose fibres followed by further deposition of anthocyanins and phenolic acids, finally resulting in penetration into the internal cavity of the fibre of at least some polyphenols. As almost all polyphenols bound to cell wall components remain bound during simulated gastric and small intestinal digestion, they would be expected to be delivered to the large intestine where fermentation and metabolism by gut bacteria can occur. The extent of release and uptake of polyphenols bound to cell walls by gut bacteria fermentation and the effect on large bowel health should be addressed in future studies.

The role of the short stature homeobox-containing gene in skeletal growth and development

Munns, Craig Frank John — 2007-08-24T00:00:00Z

The role of the ubiquitin protein ligase, Nedd4-2, in neuronal development

Prudence Donovan — 2012-03-28T00:00:00Z

Correct ontogeny of the nervous system is reliant upon exquisite regulation of exogenous growth factors and their cellular reception. Integration of a myriad of signalling pathways during the development of the nervous system results in up to 100 billion nerve cells differentiating and migrating to take the their place in the elegant neuronal network that underpins brain homeostasis. The importance of such receptor ligand interactions to the proper initiation of neuronal differentiation, outgrowth and innervation has been demonstrated using a variety of structure- function studies, analysis of knockout animal models, protein-protein interactions and behavioural studies. Despite this, at present, knowledge concerning how such a vast array of signalling pathways are coordinately regulated to achieve the appropriate temporal and spatial regulation of neurogenic proteins is deficient. Modulation of the functional protein output of cell can be regulated by ubiquitination. Attachment of ubiquitin to a target protein is a post-translation modification carried out primarily by ubiquitin protein ligases that bind to consensus motifs on target proteins and conjugate ubiquitin chains to lysine residues within that protein. This process is known to label proteins for recycling or degradation in the proteasome. Thereby providing a mechanism for the removal and attenuation of a proteins signalling potential-when and where it is required. Such a modification is rapid and provides regulation of a protein that is context dependent and easily reversible, therefore providing a on/off switching mechanism, appropriate to the formation complex networks, as seen during neuronal development. Nedd4-2 is an ubiquitin protein ligase that is developmentally regulated; the protein was first identified from a subtractive cDNA library as developmentally down-regulated transcript in the brain. The expression of Nedd4-2 peaks at the time of neurogenesis and is maintained at significantly lower levels in the adult brain. Presently, the knowledge concerning the regulation of Nedd4-2, protein recruitment by Nedd4-2 and how this regulates neuronal development is lacking. Early studies of protein recruitment by Nedd4-2 indicated that it binds to target proteins through a consensus PY motif, despite a small list of proteins being identified and characterized as targets of Nedd4-2 mediated proteolytic degradation; the role of Nedd4-2 has largely not been characterized in the mammalian brain. Therefore, the key focus of this thesis was to examine the role of Nedd4-2, in neuronal development by defining and pinpointing where and how Nedd4-2 influences initiation of neurite development,differentiation and survival. The work presented in this thesis addresses this by establishing the importance of Nedd4-2 expression in regulating neurite outgrowth in PC12 cells. Studies presented here indicate that Nedd4-2 acts to negatively regulate neurite development in PC12 cells, furthermore it is demonstrated that neurogenic proteins such as NGF and Ras differentially regulate Nedd4-2. This work was extended into an in vivo model, made possible by the generation of Nedd4-2 knockout mice. These studies demonstrated the importance of Nedd4-2 in maintaining homeostasis, indicating that complete abrogation of Nedd4-2 expression is peri-natal lethal. Histological assessment of key brain regions developing at this time indicates that the absence of Nedd4-2 is accompanied by deranged development of cortical areas in the brain. To gain insight into molecular mechanisms that mediate the phenotype observed in both the in vitro and in vivo modelling of Nedd4-2 during development an in silico screen was performed to develop a definitive list of putative binding candidates, this revealed the extent of the potential role for Nedd4-2 in regulating biological processes. Most notably, it was shown that PY containing proteins are enriched in pathways that regulate axon guidance receptors and the cytoskeleton. Of this list, it was demonstrated for the first time that Nedd4-2 binds to the axon guidance receptor, Neogenin and that Neogenin is ubiquitinated most likely in a Nedd4-2 dependent manner, highlighting the importance of Nedd4-2 in regulating the cell surface expression of proteins. Furthermore, prediction of the Nedd4-2 interactome led to the identification and characterization of MAP2 as a novel Nedd4-2 binding protein. These studies gave rise to the novel observation that Nedd4-2 is a potent regulator of the neuronally expressed MAP2 and indicate that Nedd4-2 can effect the differentiation and branching behaviour of nascent neurons possibly through destabilization of tubulin polymerization. Taken together this thesis demonstrates that Nedd4-2 is an important negative or rate-limiting regulator of neuronal differentiation and development in the embryonic brain, dorsal root ganglia and in PC12 cells. Furthermore, it is suggested that ubiquitin-mediated regulation of Nedd4-2 ligands such as MAP2 and Neogenin may be the effectors of the phenotype observed in the Nedd4- 2 knockout mice. This thesis also contributes to the broader understanding of how complex and convergent signalling networks are discretely regulated to achieve proper development and homeostasis.

The Role of Tissue Inhibitor of Metalloproteinases-3 (TIMP-3) in Haematopoiesis

Yi Shen — 2011-03-23T00:00:00Z

Haematopoietic stem cells (HSC) give rise to haematopoietic progenitor cells (HPC) which terminally differentiate into all blood cell types. HSC can reconstitute the haematopoietic system following damage and reside in specific micro-domains of the bone marrow (BM) known as niches. HSC niches are preferentially located at the interface between the bone and BM (endosteum) and are abundant in long bones. Molecules expressed in these niches provide the extrinsic cues that control HSC quiescence, self-renewal or differentiation by asymmetric division. Many proteins found in these niches are involved in the egress of HSC into the blood during mobilisation. These proteins include proteases such as neutrophil elastase, cathepsin-G and matrix metalloproteinases (MMP), as well as their inhibitors, α1-antitrypsin (serpina1) and tissue inhibitor of metalloproteinases (TIMP)-1 to -4. TIMP-3 is a less studied member of the TIMP family. It not only regulates MMP activity but also the activity of sheddases (and thus plays a role in cytokine maturation), prevents vascular endothelial growth factor binding to its receptor 2, inhibits cancer proliferation and can cause sorsby fundus dystrophy. Despite its many interesting functions, TIMP-3’s role in haematopoiesis and mobilisation has not been well documented. By qRT-PCR and reverse zymography, I have determined that TIMP-3 mRNA is expressed at a 10-fold higher level at the endosteum when compared to central BM. Multipotent stromal cells (MSC), endothelial cells and mature osteoblasts (OB) expressed high levels of TIMP-3. Erythroid progenitors, megakaryocyte progenitors and mature megakaryocytes expressed TIMP-3 mRNA at much lower levels than stromal cells, while all other haematopoietic cells expressed extremely low to undetectable levels of TIMP-3 mRNA. Immunohistofluorescence on paraffin embedded bone sections with a rabbit anti-human TIMP-3 antibody (which cross-reacts with mouse TIMP-3) validated TIMP-3 protein expression in endothelial cells, OB and megakaryocytes. Interestingly, TIMP-3 mRNA and protein expression decreased with granulocyte-colony stimulating factor induced mobilisation. To investigate TIMP-3 function, human TIMP-3 (huTIMP-3) cDNA was over-expressed in mouse HSC via retroviral transduction using MND-X-IRES-eGFP (MXIE) retroviral vector. In mice transplanted with HSC transduced with MXIE retroviral vector containing huTIMP-3 cDNA, the frequency of B-cells and T-cells over-expressing huTIMP-3 were significantly reduced in blood and BM when compared to mice transplanted with HSC transduced with control empty vector. Conversely, the frequency of huTIMP-3 expressing myeloid cells was significantly higher in the blood, BM and spleen. Blood leukocytes and splenocytes of mice over-expressing huTIMP-3 in haematopoietic cells exhibited significantly greater colony forming ability. The presence of huTIMP-3 also increased Lineage-Sca-1+Kit+ stem cell proliferation both in vivo and in vitro. Interestingly as well, long term over-expression of huTIMP-3 resulted in calcification of bones with markedly decreased BM content and ultimately death.

The role of Tomosyn in insulin-regulated GLUT4 trafficking

Widberg, Charlotte Heidi. — 2011-12-22T00:00:00Z

The role of trust in community acceptance of urban water management schemes: A social-psychological model of the characteristics and determinants of trust and acceptance

Victoria Ross — 2010-06-04T00:00:00Z

Given the important role that trust plays in acceptance of water management schemes, the current research investigated the characteristics and determinants of trust by developing a social-psychological model of trust in the area of water management and reuse. The research advanced a theoretical understanding of trust by using social identity theory and the relational model of trust as a framework and providing a systematic examination of the relationships between the variables in the hypothesised trust model. The proposed trust model was tested across three potentially different perceived risk contexts; low, medium and high. Analysis through path modelling provided strong support for the hypothesised model. In all three contexts trust in the water authority was a significant predictor of acceptance of the water management scheme, and risk perceptions mediated the relationship between trust and acceptance. In other words higher levels of trust in the authority were associated with lower perceptions of risk, which were in turn associated with higher levels of acceptance. In Study 4, which was set in the high perceived risk context of the proposed indirect potable reuse scheme in Toowoomba, perceptions of risk had the strongest direct effect on acceptance of the scheme, and the trust, risk and acceptance relationship was stronger than it was in the other studies. The relational variables of procedural fairness, identification with one’s community, ingroup membership of the water authority and a social bond (shared values) with the water authority were all found to impact on trust, either directly or indirectly. In addition, the instrumental variable of the credibility of the authority (measured as technical competence and a lack of vested interests) was found to have a significant impact on trust. Taken together, the results provide support for social identity theory and the relational model of trust as a framework for understanding trust in authorities. The results are also consistent with literature that suggests that the relational and instrumental models of trust are not incompatible (e.g., Edwards & Kidd, 2003; Tyler & Kramer, 1996). The findings from this research program clearly have a practical application for improving acceptance of water management schemes. The combined results demonstrate the importance of trust in the water authority in reducing perceived risk and thus increasing acceptance of schemes. The results highlight the need for water authorities and policy makers to build public trust through procedural fairness, building a sense of the water authority as a member of the community, and through demonstrating technical competence and concern for the interests of the public.

The Role of Ultraviolet Radiation in Molecular Pathways to Melanoma

Hacker, Elke — 2008-11-21T00:00:00Z

A great deal of cancer research is aimed at describing the precise mechanisms that allow cells to become transformed. Many genes have been associated with melanoma and the majority of the functions of these genes pertain to three pathways Ras/Raf/MAPK, Ink4a/Cdk4-cyclin/pRb and ARF/Mdm2/p53. Over-expression of Hras in melanocytes, combined with a single neonatal UVR dose is sufficient to induce melanoma in pigmented mice. These lesions were small in situ cutaneous melanomas. To assess the role of the pRb pathway in melanoma mice, over expressing Hras were combined with activated Cdk4 mutants. These animals develop melanoma spontaneously, with a penetrance of 58%, which rose to 83% after neonatal ultraviolet radiation (UVR). Furthermore, the entire UVRtreated cohort that developed melanoma had multiple cutaneous lesions and 92% had metastatic tumours. In this model Hras activation alone is sufficient to predispose melanocytes to UVR-induced transformation, while mutant Cdk4 is more important for tumour progression, producing larger more aggressive, metastatic melanomas. To further assess the Ink4a/Cdk4-cyclin/pRb pathway in this disease a melanocytespecific deletion of the Rb1 gene was constructed. This model allowed for the culturing of Rb1-null melanocytes. Rb1-null melanocytes were studied and found to proliferate more rapidly than controls and to have a decreased requirement for mitogens. Expression arrays were performed to identify differences between the small in situ TPras lesions and those more aggressive Cdk4[superscript]R24C/R24C/TPras melanomas. We observed up regulation of Tcfeb, Ednrb, Tcfap2b and Gpr155 and down regulation of Plagl1 in Cdk4[superscript]R24C/R24C/TPras lesions. The overlay of expression and aCGH analysis showed dysfunction of various genes that are involved in regulating p53 and DNA repair pathways in the Cdk4[superscript]R24C/R24C/TPras tumours (Plagl1, Abcc10, Hsp90aa1 and Htatip). We also observed aberrations of several genes that regulate p21 (E2F2 and Htatip) and identified several potential markers of melanoma progression (Pax7, Dpp3, cdc42, Fgf22, Nme2, Esm1, Ednrb, Mum1 and Notch4). We also identified several genetic changes in Cdk4[superscript]R24C/R24C/TPras tumours that were specific to either UVR-induced or spontaneously derived lesions and identified a number of candidate genes (Hsp90aa1, Gzmk, Esm1, Bop1, Rapgef3, Htatip and Dpp3). This study has identified numerous novel candidate genes and also confirmed the importance of various melanoma-associated genes in this disease.

The role of universities in the development of regional innovation systems in Australia

Gunasekara, Chrys. — 2007-08-24T00:00:00Z

THE ROLE OF UNPLANNED HUMAN SETTLEMENTS IN LAND COVER CHANGE: A CASE STUDY OF THE CHYULU HILLS SQUATTERS- KENYA

Grace Muriuki — 2011-03-21T00:00:00Z

Investigations in this thesis advance our understanding on the role of unplanned human settlements in land cover change. Despite its complexity, the fundamental causes of land cover change are well known, and comprise biophysical, economic, policy/institutional and demographic factors. Of these, population growth and migration are implicated as the most significant. In future almost all land cover change will occur in rural areas which are experiencing rapid increases in population and migration, already a critical concern for conservation programs worldwide. Squatters are immigrants who illegally establish residence in areas deemed unsettled or with poorly-defined tenure. Their land use decisions tend to be risk-minimization strategies, influenced by their socio-economic characteristics and lack of long-term stakes in the land they occupy. This reduces their motivation to invest in and conserve resources, and they often become exceptional land degraders. In order to reduce their impact on landscapes and minimise the conflicts associated with their settlements, there is need for targeted research on their role in land cover change. I contribute knowledge to this problem using the Chyulu Hills as a case study. First, I reviewed current knowledge on migration and land cover change and the influential structural constructs that guide research in this field. Based on this review, I evaluated the dynamics of squatter migration to the Chyulu Hills, and the history of conflicts of squatters with the protected areas. Combining community surveys with statistical analysis, I revealed the proximate and underlying causes of the migration. I found that squatter movements to Chyulu Hills were widespread and long term, and that squatters are drawn from all over Kenya. Household socioeconomic and policy-related factors such as provision of schools, land tenure security and issuance of free land had a strong influence on squatter migration. Land and settlement policies were also implicated in migration and squatting. Most significantly, I established a high prevalence of secondary migration, where squatters migrated repeatedly to maximise their livelihood opportunities. The responsiveness of squatters to policy stimuli highlighted its potential to regulate or influence squatter mobility in rural landscapes. Next, I combined remote sensing/GIS tools, community surveys and landscape metrics to evaluate the rates and patterns of land cover change in the Chyulu Hills between 1967 and 1999, a period of high squatter migration. I found rapid changes in land cover over the 32 years of squatter settlements. The total proportion of native vegetation (dense forests, open forests and shrublands) decreased from 91% to 36%. In the same period, dense forests declined by 8.7% while cultivation expanded by approximately 40%. I explained these changes in the context of policy and management of land and the protected areas of Tsavo and Chyulu Hills. Squatter problems were related to land alienation during the British colonization of Kenya. I found preferential patterns of village establishment in or near dense forests. Landscape fragmentation confirmed the spontaneous nature of squatter settlements, and it is not clear yet how these transformations might affect the wildlife that uses it as a dispersal area. The community knowledge of the patterns and processes of land cover change, assessed using an adapted semi-quantitative tool known as proportional piling, agreed well with quantitative GIS measures of land cover change. Following this, I tested alternative postulates of the role of biophysical, household socioeconomic, access and institutional factors in the variation in remnant vegetation in villages in Chyulu Hills. Using Generalised Linear Models, model averaging and hierarchical partitioning analyses, I selected the best set of models within a 95% confidence interval, and ranked the relative importance of the explanatory factors in the variation in remnant vegetation. I found that squatter presence and their associated characteristics of short stays in villages, larger households and younger household heads were the most significant factors in remnant vegetation variations. This was supported by results of hierarchical partitioning. I then analyzed the policy on management of squatters and protected areas. For the most part, squatter management is ad hoc and reactionary, biased towards urban squatters, and largely limited to site and services improvements. I argued that this arose from a multiplicity of governance institutions and policies for natural resource management with overlapping mandates, rigid conservation management paradigms, and lack of provisions for participatory engagement of all stakeholders. I proposed the promotion of enabling policy environments that embrace participatory opportunities supported by building squatter human and social capital. Long-term land use planning should consider alternative livelihood sources that are less dependent on land as viable opportunities for reducing landscape changes and conflicts associated with squatters in rural areas. I recommend further research that integrates a broader spectrum of exogenous and contextual factors such as national policies, droughts and pandemics such as HIV/AIDS that influence household socioeconomics in rural land cover change. I also propose predictive studies that build potential future scenarios and that utilise finer temporal and spatial resolutions.

The roles of manganese and manganese transport systems in the response to oxidative stress in Neisseria gonorrhoeae and Streptococcus pneumoniae

Tseng, Hsing-Ju (Hilda) — 2007-08-24T00:00:00Z

The "rules of engagement": Social conventions surrounding the communication of criticism

Carla Jeffries — 2012-04-27T00:00:00Z

Criticism is important because it carries the potential for growth and positive change. Criticism holds the potential to identify weaknesses and suboptimal behaviours and, if acknowledged and integrated, can lead to the positive transformation of an individual or a group. Despite the therapeutic benefits of criticism, communicating critical feedback is a difficult behaviour. Criticism is frequently experienced as threatening and, when delivered or “taken” badly, can lead to a cascade of negative consequences (damaged self-esteem, hurt, conflict, withdrawal). Because it carries so much potential for hurt, the delivery of negative feedback is bounded by complex codes of etiquette. The present thesis aims to provide the first comprehensive map of these “rules of engagement” and to explore their psychological underpinnings and consequences. Chapter 2 describes the extant literature pertaining to the communication of interpersonal criticism. It then presents a survey study (N = 849) examining the extent to which people view the communication of criticism as more or less appropriate across various targets and in various contexts. We found evidence that respondents calibrate their feedback as a function of (a) the psychological resilience of the target, (b) whether the target is mutable, (c) whether the target deserves punishment, and (d) whether the target lies outside or within the boundary of one’s extended self. The effects are robust across age and gender. Cross-cultural differences in the endorsement of some rules were identified. Chapter 3 presents a study (N = 263) that disentangles the extent to which the withholding of negative feedback is motivated by a desire to protect the self as opposed to a desire to protect the target from the damaging social consequences of criticism. We found that participants provided more negative essay feedback if they thought that their assessments were anonymous than if they anticipated providing feedback face-to-face with the essay writer. Feedback was most negative when the feedback was not to be delivered to the essay writer at all. This effect only emerged among participants who were low in self-liking (but was unrelated to perceptions of self-competency). Manipulations of the self-esteem of the essay writer had no effect at all on evaluations. The data lend strong support for a self-protection motive and more modest support for an other-protection motive for withholding negative feedback. Chapter 4 presents two studies investigating the normative protection of low status groups from criticism. Study 1 (N = 816) identified the “David and Goliath” rule – the tendency for people to perceive members of “David” groups (groups with low power or status) as more “off-limits” to criticism than “Goliath” groups (groups with high power or status). We identified the existence of the David and Goliath rule across five national samples (Study 1). However the rule was endorsed more strongly in Western than in Chinese cultures, an effect mediated by cultural differences in power distance. Study 2 (N = 302) identified the psychological underpinnings of this rule in an Australian sample. Lower social dominance orientation (SDO; Pratto, Sidanius, Stallworth, & Malle, 1994) was associated with greater endorsement of the rule, an effect mediated through the differential attribution of stereotypes. Specifically, those low in SDO were more likely to attribute traits of warmth and incompetence to David versus Goliath groups, a pattern of stereotypes that was related to the protection of David groups from criticism. In Chapter 5, three studies investigated whether men and women are viewed as more or less appropriate to criticize. In Studies 1 (N = 502) and 2 (N = 129) we identified the tendency for people in both community and student samples to view women as more “off-limits” to criticism than men; coined the gender rule. This effect was moderated by participant gender with male participants endorsing the gender rule to a greater extent than female participants. Study 3 (N = 163) demonstrated that the gender rule is not a broad brush tendency with all women receiving protection from criticism. Consistent with work on stereotype content, both male and female targets occupying communal roles (high warmth-low competence) received less negative feedback than male and female targets in agentic roles (low warmth-high competence). These differences in performance evaluations could not be explained by differences in performance expectations or endorsement of benevolent or hostile sexism. In sum, this thesis demonstrates that there are rules that govern the delivery of criticism. We argue that the ironic consequence of “protecting” certain individuals and groups against criticism is that these people and groups are not given the same opportunities to learn and grow from their mistakes. The potential for miscommunication – and the perverse implications of withholding criticism – are discussed in Chapter 6.

The scalability and validity of four visual perceptual instruments : a comparison using the Rasch Measurement Model

Brown, G. Ted — 2007-08-24T00:00:00Z

The Science and Policy of Greenhouse Gas Management: A study of Australian and British stakeholder understanding, demands and expectations within the anthropogenic climate change discourse

Graham Farebrother — 2011-11-15T00:00:00Z

This study examines the science and policy interactions of greenhouse gas management (GHG) in Australia and the UK. It takes an historic approach, detailing how human recognition of Earth System impacts developed. As perturbations to different aspects of the Earth System were increasingly recognised, concerns grew for the sustainability of the natural world, and consequently for the sustainability of the economic system that underpins human societies. Over time, impacts and problems of increasing complexity have been identified, and it has become evident that an ad hoc manner of economic advance cannot be perpetuated. Much global and nation state effort is currently dedicated to designing and implementing policies to mitigate and manage the expected far-reaching impacts associated with anthropogenic climate change (ACC). The ACC discourse has progressed rapidly in recent times. Speculation of human interference in the Earth’s climate began in the 19th century; this speculation progressed into warnings in the 1930s, followed by quantitative measurements of atmospheric perturbation in the 1950s. Fears of anthropogenic disruption to the Earth System in the form of climate change have since resulted in international agreements, underpinned by concepts of sustainable development, and the precautionary principle. During the second half of the 20th century, civil society grew in strength and adopted a more powerful role in decision making processes and governance within many nation states; a process that has been actively encouraged through the activities of the United Nations. This change, in conjunction with a growing Green ethic, driven by the observation of environmental damage and impacts, has enveloped many aspects of human activity. As the level of industrialisation has increased in both scope and geographic range, environmental impacts have grown from local to regional to global and, with the onset of predictive computer modelling, bleak scenarios of future conditions have ensued. A growing knowledge base pertaining to various aspects of ACC has merged with both the expectations of an increasingly more powerful civil society, and an increasingly pervasive Green ethic. Following the introduction of the United Nations Framework Convention on Climate Change in 1992, GHG management has been at the fore of global and nation state policy discussions. The ACC discourse has since become increasingly embroiled with issues of sustainability; equity between developed and developing countries; and, the maintenance and promotion of the economic positions of various developed countries and trading blocs. Because of the broad association of GHGs with a variety of human activities, the discourse is seen by many as an umbrella cause. The goal of reducing anthropogenic GHG perturbation of the atmosphere has been coopted to heighten the awareness of many environmental and social problems, and to underpin the promotion of a range of vested interests. To understand the role of science in the development of GHG management policies, this study examines stakeholder understanding, perceptions, and expectations of both climate change science and mitigation policies. Interviews conducted in the UK and Australia, that targeted vocal and affected stakeholders, suggested that a high level of expectation is associated with the outcomes of GHG management policies; beyond the direct minimisation of climate interference, other environmental and societal improvements are expected. The ACC discourse is associated with a broad swath of issues that are found within contemporary society and deemed to be in need of resolution. The discourse is not only linked to existing and well known issues such as tropical rainforest deforestation, developing country poverty alleviation, biodiversity decline, and waste management but also to emerging problems including resource decline, rampant consumerism, falling human health standards, environmental degradation, and low levels of societal wellbeing. These associations are shown to be strong even when stakeholders have limited knowledge of, or even regard for, the underlying science of ACC. As a consequence of these many and varied associations, that have different sets of emphases from different elements of civil society, and in different locations, instigating universally acceptable GHG management policy is suggested as being problematic. Findings from this research suggest that if a greater focus on quantifiable environmental and societal improvement was a component of localised GHG management policies, then their acceptance and uptake by civil society would be eased and enhanced. The study shows that many less than ideal conditions and norms have developed within different societies and that a focal point is widely recognised as being useful or even necessary to help identify and rectify such problems. At both local and global levels, because of its direct association with Earth System impacts and the links to unsustainable forms of human behaviour, GHG management could be such a focal point if it is appropriately used.

The search for meaning in music education: Reflections on difference and practice.

Cuskelly, James Martin — 2008-11-21T00:00:00Z

This thesis investigates issues of meaning in music and the ways in which music education can be organised and delivered to maximise the experience of meaning for students. Two key questions are pursued within this thesis. Firstly, what is the nature of meaning in music, both as it is reported by educators and students, and evidenced in the literature? Secondly, in what ways can music education curriculum be organised to maximise this experience of meaning for students, specifically in the core areas of listening, composing and performing? In recognizing the various ways in which concepts of musical meaning are employed within music education and in an attempt to clarify and more accurately define what is intended when referring to meaning in music, three specific terms-signification, responsification and socialification-are suggested. The use of these terms also provides important points of reference throughout the discussion. Employing an autobiographical and phenomenological approach alongside a critical analysis of music education philosophies, this study investigates the lived experiences of teachers and students in terms of meaning in music. The inclusion of personal histories-my own and the stories of the students whom I teach-within the methodological framework provides a unique vehicle for the capture of data given the highly personalised nature of much of the material to hand. Further, a consideration of the lived experience of teachers and students in light of contemporary research and thinking serves to firmly anchor the discussion within the educational context. This research has found that issues of meaning are layered, multifaceted and interrelated, that there are numerous elements that contribute to meaning and that what is significant in music may be diverse, varying from individual to individual, from group to group. Musical meaning may be highly personalized and /or culturally delineated, and meaning in music may not remain static; it may vary across experiences or over time. This research has identified particular practices and approaches which significantly influence the development of meaning in music; such educative practices are worthy of sustained consideration by those within the field.

THE SELF EVALUATION MAINTENANCE MODEL IN ADOLESCENT SIBLING AND TWIN RELATIONSHIPS

Blakeley-Smith, Anita Maria — 2008-11-21T00:00:00Z

The project was designed to examine how nontwin and twin sibling adolescents deal with situations of competition and comparison between them. Using the Self Evaluation Maintenance Model (Tesser, 1988) as a framework, this project explored the reactions and strategies that adolescent nontwin and twin adolescents employ in order to maintain a positive selfevaluation. In addition, the potential mediating factors of sibling relationship quality and perceptions of differential parental treatment on adolescents reactions to competition and comparison to their self esteem was also investigated. Three studies were conducted. All three studies investigated the relevance of the SEM model to understanding nontwin and twin adolescents reactions to situations of competition and comparison, but employed different methodologies and samples. Study 1 involved both members of the sibling pair completing a questionnaire that included their emotional and behavioural reactions to selfgenerated situations of competition and comparison, counterbalanced by closeness, relevance and performance. In this study, closeness referred to either a sibling or friend comparator. Four hundred and sixty (232 pairs of) same sex nontwin and twin adolescents aged between 13 and 17 took part in Study 1. The results revealed that both sibling nontwin and twin adolescents were motivated to maintain a positive self evaluation. In line with the SEM model, both the comparison and reflection processes were evident for emotional reactions. However, closeness of the competitor did not interact with selfrelevance of the task to affect performance as predicted. Self evaluation was enhanced when both nontwin and twin adolescents were outperformed on tasks of low rather than high self relevance, indicating the presence of the reflection process. However, nontwin adolescents reported being more positive about being outperformed by their sibling than their friend suggesting that siblings may consider their friendships to be the closer relationship to them. Closeness of the competitor did not affect positive reactions to competition and comparison for twin adolescents. For negative emotional reactions and behavioural reactions, closeness of the competitor did not interact with relevance to affect performance for either nontwin or twin adolescents as predicted. Birth order was found to affect self evaluation, even in twin relationships. Both younger nontwin and twin adolescents were more able to preserve self evaluation when outperformed by their older sibling, while older nontwin and twin adolescents found being outperformed by their younger sibling to be particularly difficult. Zygosity effects were only found for positive but not negative emotional reactions. Contrary to expectations, perceptions of differential parental treatment did not mediate emotional reactions to self esteem for adolescents. Sibling relationship quality did not mediate emotional reactions to self esteem for nontwin adolescents. When outperformed by their twin, sibling relationship conflict and sibling relationship warmth was found to mediate emotional reactions to self esteem for monozygotic twins and dizygotic twins respectively. A subsample of Study 1 participants completed Study 2. The participants in Study 2 were one hundred and six (53 pairs of) nontwin and twin same sex adolescents. Study 2 explored nontwin and twin adolescent siblings emotional reactions to situations of competition and comparison in an experiential context, again using the SEM model (Tesser, 1988) as a framework. Sibling pairs were asked to orally discuss situations where they had competed with or compared themselves to their sibling/twin, to view themselves completing this discussion and then to complete a series of questions relating to Tessers (1988) SEM model. Subjects completed the same questions for each of the four SEM conditions, counterbalanced by performance on the task and relevance of the task. As adolescents only competed against a close competitor (i.e. their sibling), the relevance of the task was the determining factor as to whether the processes of reflection and comparison would be utilised. The comparison and reflection processes were indicated for both positive and negative emotional reactions for nontwin and twin adolescents. Unlike Study 1, birth order, zygosity effects and mediating effects of sibling relationship quality were not found. Study 3 involved comparison of nontwin and twin adolescents in terms of self evaluation maintenance within the framework of the SEM model in both the retrospective and experiential context. In this study, closeness was assessed in terms of genetic similarity. Monozygotic twins showed the most positive emotional reactions to performance against their twin than dizygotic twins and siblings in both contexts. For retrospectively recalled situations, siblings, rather than twins, reported the most negative reactions to being outperformed on highly self relevant tasks compared to monozygotic and dizygotic twins. This project found that the SEM model (Tesser, 1988) provided a more valid framework for explaining both twin and nontwin adolescent siblings self evaluation maintenance than a strictly social comparison approach. The results of all three studies were interpreted as being generally consistent with the SEM model. The results contribute new insights into differences in self evaluation maintenance between nontwin and twin adolescent siblings and provide direction for future research into the potential role of birth order, sibling relationship quality and attachment in adolescents self evaluation maintenance.

The sensory biology and feeding behaviour of sawfish

Barbara Wueringer — 2011-04-13T00:00:00Z

The family of pristid sawfish face a global crisis, with all species listed as critically endangered on the IUCN Redlist. One characteristic that all species have in common may also be a major factor contributing to their decline; the elongated rostrum that bears lateral teeth (the ‘saw’). As the saw becomes easily entangled in fishing gear and is also a valuable trophy, sawfish are regularly taken as by-catch. However, the use of the saw has never been studied. My objective is to identify the importance of the saw during prey manipulation, and to assess the relative importance of three sensory modalities (vision, electroreception and mechanoreception) in the same context. The morphology of the rostrum of pristid sawfish was analysed and compared to rhinobatid shovelnose rays and the extinct sclerorhynchid sawfish, as these three families are monophyletic. Comparison of the internal structure of the rostrum in the three taxa indicates that in pristids the anterior portion of the rostrum lengthened, which results in a slimmer construction than that of the sclerorhynchid rostrum. Moreover, pristid rostral teeth grow continuously from the base, whereas sclerorhynchids possess functional rostral teeth and dormant replacement teeth. Characteristics of the pristid rostrum are interpreted as adaptations to reduce weight and therefore potentially allow fast lateral swipes of the rostrum during food manipulation. Contrary to other batoids, the atlanto-occipital joint of pristids allows free movement of the cranium in all directions. Feeding observations of juvenile freshwater sawfish Pristis microdon lead to the establishment of an ethogram in the context of prey manipulation. Results indicate that an average feeding event that leads to the successful ingestion of a fish is comprised of five behaviours, of which at least one includes the use of the saw. However, freshwater sawfish use their saw during prey manipulation in three distinctive behaviours. Comparison of the two dimensional sensory array of the electroreceptive ampullae of Lorenzini in rhinobatids and pristids reveals how the elongation of the rostrum may have expanded the food spectrum of pristids: the total number of ampullary pores distributed ventrally on the head and rostrum of the pristid Anoxypristis cuspidata (490.3 ± 68.7) equals that of the rhinobatids Glaucostegus typus (452.0 ± 162.8) and Aptychotrema rostrata (461.5 ± 17.7). However, A. cuspidata possesses more than seven times the number of pores on the dorsal surface of the rostrum (297.1 ± 56.6 pores) than the rhinobatids (A. rostrata 40.7 ± 2.3 pores, G. typus 24.9 ± 5.1 pores), indicating that pristids can potentially sense the electric field of prey in the water column. One retina of a juvenile freshwater sawfish P. microdon was analysed in a retinal wholemount. The density distribution of photoreceptors shows several peaks mediating acute vision, which is comparable to the retina of a white tip reef shark Triaenodon obseus. These peaks may help sawfish to maneouvre structurally complex habitats, such as mangrove roots in rivers in order to hide from predators. Peaks in the rod and cone density of the temporal region may be useful during prey manipulation with the rostrum. Detailed knowledge of sawfish biology is crucial for maintaining optimal health of these endangered species in captivity and alleviating future fishing pressure.

The significance of ecological tolerance to fragmentation : foraging and nesting by birds in rainforest

Smyth, Anita K — 2012-11-28T13:13:51Z

The significance of enterotoxigenic E.coli as a cause of pre-weaning piglet diarrhoea in North Vietnam

Do, Ngoc Thuy — 2007-08-24T00:00:00Z

The significance of Listeria monocytogenes in eggs and egg products

Esteban, Raquel. — 2007-08-24T00:00:00Z

THE SILENCING OF DISSENT IN THE AUSTRALIAN JEWISH COMMUNITY

Salom, Margot F. — 2008-11-21T00:00:00Z

This thesis explores the experiences of Jewish peace activists in Sydney, Australia, who actively dissent from the mainstream Jewish community by expressing criticism of the oppression of the Palestinian people by various Israeli governments. Although some literature from the United States addresses the phenomenon of the silencing of dissent in the Jewish community, to date there has been very little research interest in the subject of dissent in the Australian Jewish community. This study sought to investigate the issue of dissent in the Australian Jewish community by examining the experiences of Jewish peace activists within an ethno-religious mainstream. Respondents were drawn from two Jewish peace groups in the Sydney metropolitan area. Data was generated by means of a questionnaire, which was sent to potential respondents at the time of the initial selection process. A series of semistructured, in-depth interviews followed, based on those questions and subsequent responses. The findings reveal that peace activists included in this research feel that there exists a subtle expectation/constraint within the Jewish community that disallows criticism of the Israeli government. Indeed, the majority of respondents revealed that they have personally experienced some form of silencing of their opinions and the majority of respondents either keep silent or avoid situations that would expose their views. This research also examines how Jewish peace activists perceive their identification as Jews in view of the attempts to silence their dissenting views. A majority of those interviewed agreed that they regard their activism as an expression of their Jewish identity and that they link their political stance with Jewish ethics related to justice and human rights.

The Sintering Behaviour of Al-Mg-Si-Cu-(Sn) Powder Metallurgy Alloys

Enda Crossin — 2010-03-01T00:00:00Z

The current, commercially available, press and sinter Al-Mg-Si-Cu alloys are based on wrought or cast alloy compositions and have not been tailored for the press and sinter process. The limited development of the Al-Mg-Si-Cu alloys for the press and sinter process can be partly attributed to a poor understanding of the effects of processing conditions on the sintering behaviour. The primary objective of this work was to investigate and understand the effects of processing conditions on the sintering behaviour of Al-Mg-Si-Cu-(Sn) alloys. Dilatometry was used in conjunction with other experimental techniques to elucidate and understand the expansion and shrinkage events that occur during the liquid-phase sintering of Al-Mg-Si-Cu-(Sn) powder metallurgy alloys. Samples were uni-axially pressed from elemental metal powder blends, de-waxed, and then sintered in a horizontal push-rod dilatometer to record the dimensional changes in the pressing direction. The processing conditions examined included the alloy composition, temperature, green density and atmosphere. A liquid forms during heating due to reactions between the alloying elements and the aluminium. This liquid is initially non-wetting on the oxide layer of the aluminium particles, resulting in separation of the particles, which is manifested by expansion of the sample. The oxide is reduced as sintering progresses, alleviating the non-wetting conditions. When more liquid forms, further expansion occurs, despite the improved wetting conditions. It is proposed that atmospheric oxygen and/or nitrogen can react with the liquid, forming a solid phase (‘shell’) at the liquid-vapour interfaces. These shells prevent the liquid from wetting the particles, resulting in further expansion and preventing shrinkage. Unbalanced diffusivities (the Kirkendall effect) between the aluminium and silicon contribute to the expansion. A mechanism is proposed to account for the transition to shrinkage, whereby the shells at the liquid-vapour interface rupture when there is a rapid increase in the volume of contained liquid. The liquid then flows out and over the shells, onto the aluminium substrate, causing shrinkage. Magnesium and nitrogen delay the transition to shrinkage by facilitating nitride shell formation at the solid-liquid interface. Silicon and tin cause an earlier transition to shrinkage by increasing the liquid volume. In addition, tin promotes shrinkage by segregating to the liquid-vapour interfaces, limiting the thickness of the shells at the liquid-vapour interfaces. The two dominant liquid-phase shrinkage mechanisms during the sintering of Al-Mg-Si-Cu-(Sn) alloys are rearrangement and pore-filling. Contact-flattening is not a dominant shrinkage mechanism, but may occur concurrently with the other mechanisms. If contact flattening occurs, a decrease in the pressure of isolated pores increases the total shrinkage rate. Nitrogen increases the shrinkage rate during rearrangement by restricting grain-growth. Magnesium increases the shrinkage rate during rearrangement by reducing the solid-liquid interface energy. Magnesium and nitrogen are essential for the formation of nitride within isolated pores, which decreases the pore pressure and increases the contribution of contact-flattening on the total shrinkage rate. Silicon reduces the beneficial influence of magnesium during rearrangement by diluting the magnesium content in the liquid. Silicon increases the pore-filling rate due to an increase in the liquid volume. Magnesium increases the pore-filling rate by facilitating aluminium nitride formation within isolated pores and by increasing the pore-filling. Tin additions can decrease the pore-filling rate due to its segregation to the liquid-vapour interface, limiting the consumption of nitrogen within isolated pores.

The sintering of a-alumina reinforced aluminium alloy matrix composites

Miller, David N. — 2007-08-24T00:00:00Z

The Sintering of maraging steel with phosphorous additions

Thorpe, Adam — 2011-09-20T00:00:00Z

The smoooth muscle cell cytoskeleton and regulation of phenotype

Worth, Nathalie Francoise — 2011-09-23T00:00:00Z

The social and political construction of Fijian identity and knowledge : a postcolonial perspective

Dabea, Samuela Bogitini — 2007-08-24T17:45:18Z

The social construction of economic man : the genesis, spread, impact and institutionalisation of economic ideas

MacKinnon, Lauchlan A.K. — 2008-11-21T00:00:00Z

The social construction of pedagogic discourse in health and physical education : a study of the writing of the national statement and profile 1992-1994

Sara,Glover. — 2007-08-24T17:43:06Z

The social context of familial child sexual abuse: the mother's perspective

Porter, Janet — 2008-11-21T00:00:00Z

This thesis examines the experiences of mothers whose children have been sexually abused by a male adult family member. It explores the relationships between the effect of biographical and social factors on mothers' perceptions and their experiences on learning of their children's sexual abuse. It also includes interrelated aims: a)to identify implications from the research for the development and extension of qualitative research methodology, and b)to develop and extend the understanding of the mothers' role in the sexually abusive situation. The mothers' perspectives and how they experienced the phenomenon of the sexual abuse of their child are central to the study. Historically the mother has been marginal to empirically based research while central to explanations regarding the causes and responsibility for the sexually abusive situation. Increasingly as the extent of sexual abuse as a social problem has been realised, the mother's role has been seen as central in the support of her children after the disclosure. In the literature, however, the lack of empirical research relating to the mother's experiences results in adherence to general prescriptive knowledges about motherhood. The primacy of the mothers' narratives in this study is therefore emphasised. Thirty mothers participated in the study and were a self selecting sample. They were contacted through social workers, self referral through other participants, and a private agency. The study combined quantitative and qualitative approaches. Quantitative approaches allowed the collection of socio-economic, demographic data and characteristics of the sexually abusive situation. This data was used to compare findings within and between cases and between this study and others reported in the literature. The interview guide was used as a prompt sheet rather than a structure of the interview process. The interview data contained the mothers' perceptions of their life experiences and how these affected their responses and reactions to events and relationships before and after disclosure of the abuse. This study, however, differed from much of the previous research in using qualitative approaches and in encouraging mothers to discuss what was of importance to them. The focus throughout the study was on the mothers' subjective realities and how they changed over time, as they attempted to make sense of their role in the establishment and maintenance of the abusive situation. The mothers were able to report their experiences in their own way, and were able to make their own links between ideas and perceptions which were not structured by the research process. The thirty transcripts were sorted and analysed using NUD*IST, a computer software programme for manageing non numerical, unstructured data. From the mothers' narratives four regularities and processes were noted: childhood socialisation in the family of origin, courtship and marriage, relationship to the abuser, and the disclosure of the abuse. Within each of these regularities and processes, similarities and differences were identified in relation to a number of themes and sub themes as the mothers reconstructed their experiences. The study focuses on how they experienced: the disclosure process; their relationship to the abuser, the child and perception of the abuser/child relationship; and who caused and was responsible for the perpetration of the abuse. The mothers' life experiences within different family and social contexts impacted on them in various ways. All the mothers contended, however, that for the abuser to sexually abuse the child in secret required not only the manipulation of the child but also the manipulation of others in the family and social environment. The primacy given to the mothers' experiences gives an alternative perspective to the understanding of the environments and processes involved in the maintenance and establishment of the sexually abusive situation and the mothers' role. Their accounts are local, contextualised and grounded in their life experiences. Their experiences are used as a basis for a critical analysis of family systems theory. A tentative theoretical development has also been presented using concepts from chaos theory and Foucault in a heuristic way. This study has implications for workers in the areas of investigation and therapeutic intervention. The mothers' perspectives challenge views presented in the literature about the culpability or powerlessness of the mother. Their experiences of the sexually abusive environment and processes involved, give insight into the manipulative and controlling strategies of the abusers. While the findings have limited generalisability, the methodological approach, analytical processes and extension of the theoretical understanding could be applied to other areas of social science research.

The social human : between essence and existence

Sebastien Cazaudehore — 2012-06-19T00:00:00Z

The sociality of healing Engaging Southern Sudanese refugees resettling in an Australian context a model of social healing

Westoby, Peter Ralph — 2008-11-21T00:00:00Z

Within the thesis the author examines how Southern Sudanese refugees understand healing as a social process in a resettlement context within Australia. This examination has led the author to explore first how do we understand the distress of refugees, and second, what are the social processes that facilitate healing? The author builds on the argument that if healing is at least partly a social process then the re-building of a social world for refugees is critical for recovery. Social healing is the metaphor used as a way of describing this process and a new model of intervention. The key argument of the dissertation is that contrary to much of the literature, the distress exhibited by Sudanese refugees is related more to resettlement issues than to the experiences of violence that caused their refugee status. Broadly speaking, their distress is located in the social milieu of their resettlement. It follows from this that the primary goal of intervention should be based on a model of the social that is developed in this thesis. This model differs from current intervention models in two principle ways: (i) instead of being therapeutically oriented to the individual, it requires the identification of social healing across three spheres of culture, community and power; and (ii) rather than focusing on the professional/ client relationship, intervention needs to be dialogically based on the agency of the Southern Sudanese communitys attempt to make sense of their agonistic new location in Australia. The analysis is used to tentatively theorize social healing. The author also aims to build an archive of the subjective experience of refugee distress and their aspirations for and performances of social healing. The model of social healing developed builds on the emerging critique of a psycho-social discourse as it relates to refugees in a resettlement context that represents and problematizes refugees in certain ways. The author argues that the contemporary psycho-social approach, embedded in a therapeutic discourse, constitutes refugees in particular ways that draw on a dominant paradigm that is therapeutically, individually and technically oriented. This dissertation interrupts this discursive practice through drawing on several critical intellectual traditions (anthropology, philosophy and sociology) and also through empirical work with Southern Sudanese refugees that supports the intellectual critique. The distress of Southern Sudanese refugees is made sense of through an alternative paradigm (to the dominant psychological, therapeutic and individually orientated one), through using key concepts such as cultural trauma, social trauma and social distress. These concepts orient the reader towards the collective, the social and refugee agency. Conversely a new social model of healing is then developed that explores the spheres and resources of, albeit disrupted, yet still existing, culture, community and power within the context of a dialogical and elicitive approach to intervention. The new social model provides a new map and new contours for building theory and identifying practice implications that draw on refugee emic perspectives, endogenous resources and insider action in a resettlement context. The dissertation has used an elicitive approach to research. The research methodology parallels the social model of healing articulated. Interviews, dialogue workshops and participant observation have been used to gain empirical and participant data. At the heart of the methodology is an elicitive process of dialogue that provides the opportunity for a mutual journey of discovery in re-building a social world of Southern Sudanese refugees within the spheres of: culture through for example, [re]orienting and [re]cycling cultural practice; community through for example, [re]creating bonding and bridging social capital, dealing with conflict, socializing suffering; and power through contesting political (structural and post-structural) dynamics linked to citizen rights, formal organized power, and engagement with the settlement and welfare industry. Overall the dissertation is a useful contribution to the ongoing debates about psycho-social and moral-political work with refugee communities within multicultural contexts.

The social organisation of independent writing in an early years classroom

Christina Ruth Davidson — 2012-07-17T00:00:00Z

The social-servicescape : influence of other customers on customers present

Tombs, Alastair. — 2007-08-24T00:00:00Z

The sociocultural genesis of mediational means and the construction of identities in the language other than English (LOTE) classroom

Hirst, Elizabeth Wyshe — 2007-08-24T00:00:00Z

The Song of Songs which was Solomon's : an intertextual typology of its reception

Graham White — 2007-08-24T00:00:00Z

The sorption isotherm properties of limonene-ß-cyclodextrin complex powder

Comino, Penelope Ruth — 2007-08-24T18:50:16Z

The soybean nodulation inhibitory factor SDI

Lin, Yu-hsiang — 2012-08-13T00:00:00Z

The Space and Performance of Virtual Reality

Neal Harvey — 2010-06-15T00:00:00Z

In this dissertation’s study of virtual reality (VR), I focus my attention on two prominent types of VR: real virtualities and virtual realities. I argue that both are composed of performative acts of spatial production and that through the study of those acts, researchers can isolate and describe the difference between these two tropes of virtual reality. My thesis focuses on Henri Lefebvre’s theorisation of social space as the most detailed and appropriate spatial theory for such a process while Victor Turner’s liminal theory of social and ritual performance provides the necessary performative methodology to complement Lefebvre’s. My use of these theories allows researchers to identify the difference between social spaces that produce new spaces and practices, and those which reinforce the spatial paradigm that generated them. The process of identifying these differences further clarifies Lefebvre’s complicated description of social space, but it also provides a platform for researchers to distinguish between the two different types of virtual reality. Through a detailed examination of three ostensibly different examples of VR, I argue that virtual realities ought to be considered primarily as realities made virtual while real virtualities should be discussed as virtualities made real. In doing so this thesis advances the study and application of Lefebvrean thought whilst opening up new directions for virtuality studies. I have chosen to explore three case studies that, through their difference, foreground their spatial and performative nature. By focusing on distinctly different and atypical case studies, I highlight the methodology described in this project and its suitability (or otherwise) for discussing VR. Focusing firstly on Google, I explore the virtual reality of the World Wide Web, perhaps the most ubiquitous example of a virtual reality. The sheer pervasiveness, uptake and constant evolution of the World Wide Web means that it requires constant academic attention. Google is the page through which a staggering 53.3% of Web users access the Internet and to say that most people are actually browsing Google’s web instead of the actual web is by no means an under statement. Google, like all other search engines, has its own formula for determining results and rankings for search queries. Google is not, as many people would like to think, an objective map of the Internet. It relies so heavily on users’ data in relation to their search query (which pages they click on, how long they spend there, whether they click back) that apart from the virtual algorithms that it uses to articulate the process Google could be said to be constituted solely by the real world practices of its users. Secondly I explore an example of the other type of VR, a real virtuality. Though the Gothic cathedral may not traditionally fall under the rubric of virtuality studies, the building itself provides an excellent example of the interaction of space and performance required to bring into existence that which was not there before. The Gothic cathedral is a concrete resolution of the actual/virtual dialectic and provides a unique opportunity to test my methodology’s ability to describe both types of VR and highlight the distinction between them. Whereas much of what constitutes virtuality studies centres on what I am calling the virtualisation of reality (online chat rooms, virtual banking, etc) – spaces that represent virtual others of real world entities, the Gothic cathedral represents the reverse of this: the realisation of a virtuality. The Gothic cathedral is unique in the context of this thesis for it is first and foremost a physical building rather than an onscreen other. It is a real virtuality in this thesis because, while concrete, there are some aspects of its reality that remain essential rather than formal and are dependent upon parishioners’ performance in order to be made ‘real.’ The final case study of this project represents the future usefulness of my methodology. In following up the work on exploring the suitability of describing a Gothic cathedral alongside Google, the last chapter of my dissertation explores the suitability of describing theatrical space as a VR. Similar to the Google chapter, this chapter focuses on a digital VR tool recently developed by Joanne Tompkins at the University of Queensland called the Online Theatre Project. The Online Theatre Project (OTP) represents a unique approach to the documentation, digital conceptualisation and archival problems that present themselves to a working theatre company in its everyday practice. The OTP is a server-based modeling and archival tool that allows users to draw, model and design their theatre production in real-time and then house their data on a remotely accessible server. Any notional description of theatrical space is necessarily a slippery one, given the relative youth of such studies and this project positions itself in this ever evolving debate by suggesting that the Online Theatre Project actually provides a description of what theatrical space entails where others have not. This thesis argues that VR space is dependent upon a constant spatial and performative production process. It illustrates how Lefebvre’s conceptualisation of the production process is most suitable for describing that production process and argues that re-imagining Lefebvre’s definition with the assistance of Turner’s everyday performative theory of liminality affords researchers the chance to differentiate between real virtualities and virtual realities. In doing so this thesis advances the study of VR, by proving that it is possible to discuss such complicated subjects in spatial and performative terms instead of the dominant real or un-real ones. Further, I outline the necessary adaptation of Lefebvre’s spatial triad that can be undertaken to prove its usefulness in many other aspects of VR studies.

The spacing effect in inductive learning

Zulkiply, Norehan — 2012-09-03T00:00:00Z

The spatial structure of the island economy of Indonesia : an inter-regional input-output study

Muchdie. — 2010-10-18T00:00:00Z

The Specification and Refinement of Timed Processes

Mahony, Brendan Patrick — 2008-11-21T00:00:00Z

The use of predicate transformers to model the action of sequential programs has allowed the construction of a refinement calculus for expressing the formal verification of the top-down development of sequential programs. It is shown that predicate transformers may also be used to model real-time processes. The notions of precondition and postcondition in the sequential refinement calculus are replaced by the notions of assumption and effect. In this way the formal development of real-time processes may also be expressed within the refinement calculus. Notations are developed for the specification and implementation of real-time processes within the framework of the refinement calculus. Several case-studies are presented to demonstrate the utility of this approach.

The spectroscopic properties of melanin

Riesz, Jennifer Jean — 2008-11-21T00:00:00Z

Melanin exhibits a broadband absorbance spectrum that appears to be unique amongst func- tional biomolecules. Explaining the origin of this spectrum is one of the primary challenges facing this field. Three main theories have been proposed: 1) The optical density is due to scattering, 2) Melanin is an amorphous semiconductor which then naturally exhibits broad- band absorbance, or 3) Melanin has a large amount of chemical heterogeneity (or disorder) which leads to a broadband absorbance spectrum through superposition of the absorbance spectra of many species (the chemical disorder model). We discuss these models and the experimental evidence for each. We report direct experimental evidence that the optical density is not a consequence of scattering processes, and is due to true absorbance. Distin- guishing between the two remaining explanations leads us to a discussion of the molecular structure of melanin, an issue which remains unresolved. We include a literature review, summarising the important structural findings for melanins, and conclude that the evidence suggests that melanin consists of a heterogeneous collection of small oligomers, which points towards the chemical disorder explanation for broadband absorbance. We caution, however, that the amount of chemical disorder obviously prevalent in this system is often neglected in discussions of the structure of melanin. We show that the oscillator strengths of melanin and its fundamental components are naturally explained by the chemical disorder model, as are their emission and excitation spectra and their radiative quantum yields. We show that the emission properties of melanin are not consistently reported in the literature, which is in part due to the strong re-absorption that occurs in this system, and we emphasise the im- portance of correcting for this effect in any measurement of the fluorescence of melanin. The emission properties of synthetic pheomelanin are reported, and are found to be different to those for eumelanin, suggesting different energy dissipation processes for these pigments. We also report a careful study of the spectroscopic properties of DHICA (5,6-dihydroxyindole-2- carboxylic acid), a key melanin monomer, and propose, based on these results, that proton transfer processes contribute to energy dissipation in this molecule. The radiative yield of melanin is measured to be extremely small (< 0.1%), which is consistent with melanins biological role as a photoprotectant, and suggests that non-radiative energy dissipation pro- cesses are very important for melanin. As a result of this finding we measure the vibronic structure of eumelanin related molecules using inelastic neutron scattering and accurately assign the vibrational modes using density functional theory calculations. This provides an important first step towards understanding the non-radiative processes in melanin energy dissipation and its biological functionality.

The spectroscopy of trivalent lanthanoid ions in organic hosts

Flanagan, Bernadine Mary. — 2007-08-24T00:00:00Z

The spiritual teachings of Prabhat Ranjan Sarkar : descriptive philosophy and critical comparisons

Kang, Chris — 2008-10-07T18:04:13Z