1,201 results for Doctoral, 2013

  • Increased intake of vegetables, herbs and fruit : effects on bone in postmenopausal women : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Nutritional Science, Massey University, Manawatu, New Zealand

    Gunn, Caroline Ann (2013)

    Doctoral thesis
    Massey University

    Dietary approaches to address bone loss at midlife usually involve supplementation or fortification. We aimed to investigate a food based approach to reduce bone turnover in post-menopausal (PM) women in two studies. In the first study, we investigated whether daily inclusion of specific vegetables attributed with bone resorbing inhibiting properties was feasible. We hypothesised increased intake of fruit/vegetables to ≥9 servings/day would lower potential renal acid load (PRAL) significantly (~20mEq/day) and increase urine pH (0.5 pH units) sufficiently to affect bone markers. The results of the first study confirmed the feasibility of daily inclusion of specific vegetables, reduction in renal acid load and increased urine pH. The subsequent Scarborough Fair Study (SF) used a randomised, active comparator design to increase specific vegetable/herb/fruit intake in two groups (A and B) of 50 PM women, from ≤ 5 servings/day to ≥ 9 servings/day for 3 months while a control group consumed their usual diet (n=43). Primary outcome variables were plasma bone markers which were assessed at baseline, six weeks and twelve weeks. Secondary outcome variables were plasma inflammation markers including adiponectin, urinary electrolytes (calcium, magnesium, potassium and sodium) and dietary intake assessed at baseline and 12 weeks and urinary pH assessed twice weekly. Increased intake of vegetables/herbs/fruit reduced P1NP and CTX (osteopenia) in Group B (SF) and urinary calcium loss in both intervention groups A and B (SF) with reduced PRAL. Adiponectin, tumour necrosis factor, interleukin 6 and 10 reduced in all groups. This study showed the SF vegetables/herbs/fruit may influence bone turnover and inflammatory markers. Few human intervention studies demonstrate reduction in plasma bone resorption markers with diet. Even fewer studies demonstrate reduction without supplementation with calcium, vitamin D, alkaline substrates, concentrated extracts or consumption of large quantities of a single functional food. The SF vegetables/herbs/fruit may protect against high bone turnover and subsequent bone loss in women with osteopenia and may have possibilities as an adjuvant to pharmaceutical therapies or a holistic dietary approach to reduce bone turnover and bone loss. Trial registration ACTRN 12611000763943

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  • Short circuit co-evolution by the perfect parasites : antifreeze glycoproteins in Antarctic fish leeches (Hirudinea, Piscicolidae) : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Zoology at Massey University

    Kolb, Jürgen Bertram (2013)

    Doctoral thesis
    Massey University

    Antifreeze glycoproteins (AFGPs) play an important role in biochemical adaptation to supercooled waters and hence in the survival of notothenioid fish in Antarctica. These fishes have a well developed parasitic epifauna, which in turn is also exposed to freezing conditions. In order to retain their association with Antarctic fishes as the environment progressively cooled during the Miocene, leeches as fish-associated ectoparasites had either (i) to evolve a short circuit mechanism to acquire the necessary life-saving chemical compounds from their host, (ii) to adapt their own genome to confer protection from freezing, or (iii) to develop a combined tactic unique to their parasitic life strategy according to requirements during ontogenesis. I have found that Antarctic leeches (Hirudinea, Piscicolidae), that feed on a variety of notothenioid fish species, contain antifreeze compounds at the cellular level. I present evidence that strongly indicates an absorption pathway of AFGPs in the parasitic organisms from the fish blood as source. The physiological processes of AFGPs uptake from the intestine and circulatory distribution by haemolymph would be analogous to those enabling the fish hosts to distribute these peptides by blood within their bodies, as fish absorb AFGPs through the gut after production in the pancreas. The analysis of protein chemical structures in leech material revealed characteristics typical of fish AFGPs. Further, there are high capacities for freezing point suppression in vivo, thus biological activity of antifreeze proteins in the leech parasites Cryobdella antarctica and Cryobdella levigata. A combination of this thermal hysteresis (TH) with a specific bi-pyramidal ice crystal growth has been observed, which is typical for fish AFGPs. This confirms the presence not only of functional antifreeze macromolecules but also of true AFGPs in these parasite species. Finally, to trace the potential origin of these proteins to leech genomic information, mRNA molecules were successfully detected in C. levigata, as the intermediate step necessary for any de novo AFGP biosynthesis. These results suggest the possibility of a vi horizontal gene transfer (HGT) event in this host-parasite system and if proven would mark a further record of such a gene transfer for antifreeze molecules in Antarctica but for the first time outside the surface sea ice zone. I conclude that Antarctic fish leeches have developed a novel means of an evolutionary shortcut by co-opting mechanisms for survival in supercooled waters from their hosts in the form of biochemical exploitation and possibly in addition by HGT. To the best of my knowledge, the use of functional AFGPs after digestive absorption would represent the first example in the animal kingdom of an instantly effective adaptive advantage provided by another species under natural conditions in a quasi short circuit co-evolution. I also present results from a first survey on the leech fauna in the Ross Sea across nine species of Antarctic fishes and report one new host record for C. antarctica and three new leech-host associations for C. levigata. Finally, one new species belonging to the Piscicolidae is described, Megapodibdella kirsteni, gen. et sp. nov., from the Antarctic eelpout Lycodichthys dearborni.

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  • Maternal exercise during pregnancy affects the rat musculoskeletal system and indices of energy metabolism : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatū, New Zealand

    Rosa, Brielle Vastola (2013)

    Doctoral thesis
    Massey University

    The developmental origins of health and disease hypothesis postulates that environmental cues perceived by the developing organism during early life program long-term health outcomes. A series of studies were undertaken to examine the developmental programming effects of maternal exercise during pregnancy on offspring musculoskeletal health and energy metabolism using a rat model. Firstly, an exercise that did not cause a potentially confounding stress response in the exercising animal was identified. Secondly, pregnant dams then performed this exercise and its effects on fetal growth and the maternal stress response were quantified. Finally, the offspring of dams that exercised throughout pregnancy were allowed to grow to maturity, and the effects of maternal exercise on their musculoskeletal health and energy metabolism were assessed. Throughout these experiments, body composition was assessed by dual- energy X-ray absorptiometry, and tibial parameters were measured using peripheral quantitative computed tomography. Maternal stress was quantified by measurement of faecal corticoid metabolites. Serum concentrations of the fully and undercarboxylated forms of the bone-derived hormone osteocalcin, and expression of genes related to osteocalcin carboxylation, were measured to explore their role in the response of offspring bone and energy metabolism to maternal exercise. Two exercise types, rising to an erect bipedal stance and tower climbing, were initially tested in non-pregnant rats. Both rapidly caused changes in the tibias of exercised animals without inducing stress. In pregnant rats, both exercises increased fetal growth relative to controls, and neither caused a physiological stress response in the dams. Since rising to an erect bipedal stance had the greater effect on fetal growth, it was selected for use in the final study in which the offspring were grown to maturity. Maternal exercise throughout pregnancy was associated with sex-dependent changes in the bone and body composition of the mature offspring. Male offspring of exercised dams had increased adiposity and serum undercarboxylated osteocalcin concentrations, while offspring of both genders had lower volumetric bone mineral density at the tibial diaphysis, relative to controls. These results suggest that maternal exercise has long- term effects on the musculoskeletal system and energy metabolism, and that undercarboxylated osteocalcin may play a role in these effects.

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  • Moral uncertainty and contemporary children's fantasy fiction : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in English at Massey University, Albany Campus, New Zealand

    Lochead, Anne (2013)

    Doctoral thesis
    Massey University

    This thesis studies the interplay between mythos (story) and ethos (ethical character) in contemporary children’s fantasy fiction. In recent decades, this relationship has been complicated by two contradictory, but related, ethical tendencies. Postmodernism characteristically resists unitary accounts of morality, celebrating pluralism. Within the last twenty years, however, there has been a groundswell of interest in rethinking ethics and retrieving values from endemic moral uncertainty, often referred to as an ethical turn. This thesis contends that children’s fantasy fiction has evolved into a literature that creatively engages with this contradiction, simultaneously refusing moral certainties and demanding unflinching ethical values. This evolution is explored by comparing a selection of children’s fantasy fiction published from 1995 to 2012 with earlier exponents of this genre as well as other literary texts. The analysis is conducted through a framework of expanding ethical horizons, starting with a focus on personal contexts and then progressing to the social, political, and ideological. The thesis employs an inter-textual method. Ethical concepts are teased out by bringing literary texts into dialogue with each other and exploring links between them. Ideas from critical theory are then used to extend the trajectory of the ethical themes suggested by the fictions. Through this method, themes and texts are woven into an ethical narrative about children’s fantasy. This thesis approaches storytelling as a portal into the imagination where writers, readers and protagonists actively forge moral meaning. Traditionally, stories rich in symbol not only entertained their audiences, but also encapsulated their societies’ moral values. When society is presented metaphorically, familiar assumptions are estranged, enabling readers to see the world anew and imaginatively reconstruct their worldviews. In recent children’s fantasies, both child protagonists and child readers are required to be moral thinkers. This demonstrates a shift, not only in how ethical dilemmas are contended with today, but, by addressing children as ethical subjects, in how much moral agency is attributed to children. Children’s fantasy is a rich and layered genre particularly suited to engaging with contemporary ethical dilemmas and uncertainties. This thesis affirms its role in exploring ethical meaning and action and transmitting positive values in a climate of moral uncertainty. Emerging from this fiction, and incongruous to both postmodern consumerist society and postmodern suspicion of categorical moral imperatives, is an ethics of self-transcendent love.

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  • Development of methodologies for the characterisation of biochars produced from human and animal wastes : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Institute of Agriculture and Environment, College of Sciences, Massey University, Palmerston North, New Zealand

    Wang, Tao (2013)

    Doctoral thesis
    Massey University

    Biochar is charcoal made from waste biomass and intended to be added to soil to improve soil function and reduce emissions from the biomass caused by natural degradation to CO2. Biochar technology has many environmental benefits, such as carbon (C) sequestration, waste management, soil improvement and energy production. High quality biosolids (e.g., low in heavy metals) and animal wastes represent an adequate feedstock for production of biochars. Wide variation in biochar properties, dependent on feedstocks, process conditions and post-treatments, lead to large uncertainties in predicting the effects of biochar application on the surrounding ecology, and the productivity of particular crops under specific pedoclimatic conditions. It is essential to well-characterise biochars prior to its incorporation into soils. Therefore, the aims of this thesis were (i) to investigate the C stability and nitrogen (N) and phosphorus (P) availability in biochars produced from municipal and animal organic wastes at different pyrolysis temperatures; and (ii) to develop simple and robust methods for characterisation of C stability and nutrient availability in biochars. Two types of feedstock, (i) a mixture (1:1 dry wt. basis ratio) of alum-treated biosolids (from anaerobic digestion of sewage, ~5% dry wt. of Al) and eucalyptus wood chips (BSe), and (ii) a mixture (1:1 dry wt. basis ratio) of cattle manure (from a dairy farm) and eucalyptus wood chips (MAe), were used to produce biochars at four different pyrolysis temperatures (highest heating temperature: 250, 350, 450, and 550°C). The stability of C in charred materials increased as pyrolysis temperature increased, as proved by the increase of aromaticity and the decrease of atomic H to organic C (H/Corg) ratio, volatiles to (volatiles + fixed C) ratio, C mineralisation rate and % K2Cr2O7 oxidisable C. According to the IBI Guidelines (IBI 2012), an upper H/Corg ratio limit of 0.7 is used to distinguish biochar samples from other carbonaceous biomass based on the consideration of C stability. According to this classification system, MAe-450 and MAe-550 biochars complied with this specific C stability requirement; this was also the case of BSe-450 and BSe-550 when their H values were corrected to eliminate the contribution of inorganic H from Al oxy-hydroxides. Both organic H (Horg) and Corg forms were used in the calculation of this index instead of their total amounts, as the latter would also include their inorganic C or H forms – which can represent a considerable amount of C or H in ash-rich biochars – and these do not form part of the aromatic structure. Therefore, various methods, including titration, thermogravimetric analysis (TGA), acid fumigation and acid treatment with separation by filtration, were compared to quantify the carbonate-C in biochars. Overall, the titration approach gave the most reliable results as tested by using a CaCO3 standard (average recovery>96% with a relative experimental error MAe biochars> BSe biochars > Sechura phosphate rocks (SPR). Plant availability of P in biochars could be predicted from the amount of P extracted in 2% formic acid extractable P (FA-P). In addition, resin-P was considered as a useful test for characterising P bioavailability in soils fertilised with P-rich biochars. However, more investigations with a wider range of soils and biochars are needed to confirm this. Pyrolysis temperature played a minor role on P availability in biochars produced below 450°C compared to the influence of the type of feedstock. This was supported by the results on (i) plant P uptake, (ii) 2% formic acid extraction, and (iii) successive resin P extractions. The availability of P in biochars produced at 550°C decreased noticeably compared with that in lower temperature biochars. The Hedley P fractionation procedure was also carried out to examine the forms and transformation of P in biochar after its application into soils under the influence of plant growth. Generally, biochar P contributed to the readily available resin-P and moderately available NaOH-Pi fractions, and some equilibrium likely existed between these two fractions, both of which provided P for plant uptake. In a plant-sandy soil system, depletion of P in resin-P and NaOH-Pi fractions was attributed to plant uptake rather than conversion into less available P forms (e.g. from NaOH-Pi to H2SO4-P). High-ash biochars with high P concentrations could be potential slow-release P sources with high-agronomic values. To determine appropriate agronomically effective rates of application and avoid the risk of eutrophication associated with biochar application, it is recommended to determine available P using 2% formic acid extraction in biochars, so that dose, frequency and timing of application are correctly established. All the information obtained in this thesis will support the future use of the biochar technology to recycle nutrients and stabilise carbon from agricultural and municipal organic wastes of good quality.

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  • Remediation of New Zealand sheep dip sites using biochar and phytoextraction technologies : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Institute of Agriculture and Environment, College of Sciences, Massey University, Palmerston North, New Zealand

    Gregory, Samuel (2013)

    Doctoral thesis
    Massey University

    The practice of sheep dipping, which subjected livestock to inorganic and organic agricultural pesticides to eradicate pests such as lice and keds, is a historic practice; sheep dipping is no longer practiced in New Zealand today. Animals would be submerged in solid structures known as dips containing chemicals such as arsenicals and organochlorines with the leftover solution pumped onto surrounding soil. The use of pesticides such as these is now banned by law due to their persistence in the environment. Today an estimated 50,000 contaminated sheep dip sites exist in New Zealand representing perhaps the countries’ most significant, but understated, environmental challenge. To determine whether this historic agricultural practice had led to contamination of the environment, an investigation into the extent of contamination resulting from sheep dipping at a known historic dip site in Te Mahia, New Zealand was carried out. Characterisation of the site by arsenic soil concentration mapping revealed that 500 m2 of agricultural land has been contaminated with this metalloid and that arsenic exists at varying high concentrations through the soil profile. Environmental risk from these historic pesticides was established by analysing plant and water samples below the dip site. Staple Maori food varieties such as watercress were significantly contaminated with arsenic while water samples taken from the stream below the dip returned spiked arsenic concentrations. Based on this, it was justified that arsenic/organochlorine contamination would need to be managed to reduce their effect on these food sources. The design of a coupled remediation strategy using phytoextraction and biochar was utilized to reduce remediation times and is the basis of this thesis. Contaminated soil from the site was removed and amended with two types of biochar produced from willow feedstock. These biochars, known as 350°C and 550°C biochar were added into the soil at application rates of 30 t ha-1 and 60 t ha-1. During a series of 180 d glasshouse trials, the phytoextraction of arsenic into Lolium perenne (ryegrass) shoot tissue was analysed along with growth parameters of shoot and root biomass and corresponding response to arsenic at the molecular level. In soil; microbial activity, soil bacterial community, organochlorine concentration, and element dynamics were analysed as a function of biochar amendment. Soil microbial activity, analysed using the dehydrogenase assay (DHA), was significantly increased (P<0.05) in chlorophyll content in response to the total arsenic concentration in ryegrass shoot tissue grown on contaminated soil. The observed increases in activity of SOD, APX and steady CAT activity is suggested to be efficiently catalysing the production of harmful ROS in this soil. A 6-month field investigation into the effect of biochar amendment on the extraction of arsenic into a high biomass crop (Salix sp) resulted in significant increases of arsenic in stem biomass as a function of biochar amendment. When data was extrapolated to predict results of a long-term field trial and scale under willow treatment (stem) it was calculated that over 67.7 g of arsenic could be extracted in soils amended with 350°C biochar compared to 5.9 g extracted under control treatment. This could result - assuming a similar rate of extraction with time - in levels of arsenic concentration in soils reaching background concentrations in as little as 6 years, a reduction in remediation times of 92%.

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  • Properties of oil-in-water emulsions and ice creams made from coconut milk : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Science at Massey University, New Zealand.

    Chalermnon, Naiyawit (2013)

    Doctoral thesis
    Massey University

    Coconut milk (CM) containing coconut oil extracted from the endosperm (meat) of coconut fruit is not stable and undergoes a rapid separation into a creaming layer at the top and a serum phase at the bottom. In this study, coconut milk was separated into coconut cream (CC) and coconut skim milk (CSM). The ability of proteins in CM, CC and CSM to form and stabilise oil-in-water (O/W) emulsions containing coconut oil was investigated. The unstable nature of coconut oil droplets in CM was found to be due to types of proteins adsorbed on the surface of oil droplets, which were predominantly 11S globulins, known to be hydrophobic and salt soluble proteins. The oil droplets stabilised by 11S globulins in CM and CC were larger in size and highly flocculated, probably due to hydrophobic interaction, thus resulting in rapid creaming and phase separation, compared to those stabilised by proteins (e.g. water-soluble albumins) in CSM. Smaller droplet size with less droplet flocculation and slower phase separation was obtained when emulsions were prepared with a predominance of proteins present in CSM. The CSM-based emulsions were relatively more stable but they were only able to provide short-term stability against phase separation. The results suggest that the ability of proteins (both globulins and albumins) in CM to stabilise the emulsion oil droplets was not high because these proteins did not seem to posses the ability to provide steric and electrostatic stabilisation to the emulsion droplets stabilised by them. An addition of small molecule surfactants, particularly a water-soluble surfactant of Tween 80, induced the formation of smaller droplets in the CM- and CSM-based emulsions, thereby improving their emulsion stability to a certain extent. However, the addition of oil-soluble small molecule surfactants (e.g. mono- and diglycerides and/or partially unsaturated mono- and diglycerides) in the absence of Tween 80 caused a significant increase in droplet size of emulsions prepared from CSM. In contrast, this phenomenon was not observed in emulsions made from CM. The formation and properties of coconut milk ice creams differing in the concentration of CSM proteins, as well as ratios of solid fat-to-liquid oil (blends of coconut oil and sunflower oil) were also investigated. The differences in those variables were found to have a significant influence on the properties and stability (particle size, flow properties, droplet flocculation) of ice cream mixes as well as the characteristics of ice creams, such as overrun, melt resistance and shape retention. Several instrumental analyses, including size measurement, flow behaviour and small-deformation oscillatory tests, showed the presence of an agglomerated structural network in ice creams based on CSM containing oil blends as well as in ice creams based on dairy milk. From the findings, the agglomerated fat structural network in the CSM-based ice creams containing the suitable solid fat content at 68% could change ice creams with a slow melting rate and the more ability to retain their shape during melting compared with those of the dairy milk-based ice cream and ice creams made directly from CM. Overall the results suggest that coconut milk proteins do not possess the properties of proteins suitable for making very small droplets as well as stable emulsions against phase separation, particularly 11S globulins that are one of the major constituent proteins in coconut milk. However, albumins, which are the predominant proteins in coconut skim milk, may be suitable for use as the surface-active proteins for making smaller emulsion droplets in coconut oil-in-water emulsions, but their concentration needs to be increased for use probably by membrane filtration or freeze drying after removal of some carbohydrates from coconut skim milk.

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  • Motivation and high-stakes certification assessment : secondary school students' perceptions : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Education at Massey University, Manawatu, New Zealand

    Chapman, Jan Erica (2013)

    Doctoral thesis
    Massey University

    Senior secondary students’ future social and economic well-being is significantly affected by their performance in high-stakes certification assessment. Motivation plays a key role in students’ academic performance. In light of the dearth of literature examining students’ motivation in high-stakes certification assessment, in the domain of English, and from the students’ perspective, this study examined Year 12 students’ motivation to achieve the National Certificate of Educational Achievement (NCEA) level 2 English achievement standards over the period of an academic year. A contemporary person-in-context perspective was adopted in recognition that motivation is influenced by the interplay of personal, social, and contextual variables. A mixed methods research methodology was employed in this longitudinal two-phased study. In the first phase participants completed a series of questionnaires, and in the second phase a subsample of the participants was interviewed. Students’ motivation was examined primarily through the lens of self-determination theory. Self-efficacy, attribution theory, goal theories, and interest were also drawn on to explain facets of students’ motivation. Findings indicate that most students expected to pass a number of NCEA level 2 English achievement standards and they believed it was important to pass these. Most valued English for utility reasons. Students’ interest in English varied markedly across different aspects of the English programme. Gender differences in students’ motivation were not apparent in relation to students’ motivation-related attitudes. External and introjected regulation were the most prevalent types of motivation influencing students’ performance in NCEA English. However, their impact was not as detrimental as theory and research would have predicted. Teachers played a pivotal role in many students’ motivation to achieve, especially in relation to feedback, expectations, and student-teacher relationships. Past performance was also an important influence. Difficulties with or a dislike of aspects of English and academic demands from other school subjects were identified as negatively impacting on students’ motivation to achieve in English. Overall, students’ motivation was found to be complex, dynamic, multidimensional, and situation dependent. Matthew effects were particularly evident for high and low achievers, highlighting the bi-directional relationship between motivation and achievement. Implications for educators and researchers are discussed.

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  • The Role of Epigenetics in Amphibian Regeneration

    Taylor, Amy Janet (2013)

    Doctoral thesis
    University of Otago

    Up until recently, epigenetic mechanisms for epimorphic regeneration have not been studied. Epigenetic mechanisms present a possible method for control over the regeneration process and an explanation as to why some animals possess regenerative abilities and others do not. This thesis provides evidence for a role for histone acetylation and DNA methylation in amphibian regeneration. Results from this thesis show that histone deacetylase (HDAC) enzymes and consequently histone hypoacetylation are needed for successful regeneration with X. laevis tadpoles, treated with HDAC inhibitors, failing to regenerate tails and limbs. HDACs are also shown to be necessary for A. mexicanum tail regeneration however HDAC inhibition only slows limb regeneration in A. mexicanum. HDAC inhibition is shown not to affect limb or tail development in X. laevis but to slow development in A. mexicanum. Direct measurement of HDAC activity in X. laevis is consistent with the results of HDAC inhibitor treatment, with increased HDAC activity being associated with regeneration success in X. laevis. Regeneration competent tadpoles show increased HDAC activity with amputation and regeneration incompetent refractory stage tadpoles show a decrease in HDAC activity with amputation. HDAC activity is possibly associated with the BMP and Notch signalling pathways as well as retinoic acid signalling. Global DNA methylation is also measured in X. laevis. Low levels of DNA methylation are shown to be associated with regeneration success following amputation, with regeneration competent tadpoles showing lower levels of methylation than refractory stage tadpoles. This is consistent with the illustrated variable regenerative response to methyltransferase inhibitor treatment in regeneration competent tadpoles treated after amputation. It is also consistent with the increased regenerative success seen when refractory stage tadpoles are treated with a methyltransferase inhibitor. The evidence presented in this thesis illustrates the importance of epigenetic mechanisms in vertebrate regeneration. This research may have important implications for medical research.

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  • Fetal alcohol spectrum disorder diagnosis and intervention: An investigation of professional practice in New Zealand

    Bagley, Kerryn (2013)

    Doctoral thesis
    University of Otago

    Fetal alcohol spectrum disorder (FASD) is an umbrella term used to describe a range of neurodevelopmental and physical impairments associated with prenatal alcohol exposure. It is a brain-based disability which manifests in behavioural symptoms and cognitive deficits that adversely impact on the affected individual and their family. While FASD has been acknowledged as a disorder since the 1970s, it remains poorly understood in the New Zealand context, and does not attract much support from health and allied health services. Meanwhile, the normalization of alcohol in New Zealand culture affects the ways in which FASD is approached and perceived by medical specialists and lay people alike. This thesis investigates the ways in which professionals within health, allied health and social service systems in New Zealand encounter, approach and manage FASD and cases of suspected FASD. It examines the circumstances surrounding diagnosis of and intervention for FASD in New Zealand, and the factors that inform professional practice in these two fields. It questions how FASD fits within specific professional practice contexts, how social and cultural forces influence the actions of professionals, and what barriers may exist in FASD-related practice. It aims to provide a nuanced analysis of how FASD is currently handled, and suggests potential strategies for achieving more effective service provision for FASD. The research presented in this thesis is theoretically and methodologically grounded in applied medical anthropology, involving extensive participant- observation fieldwork in health and allied health training contexts in New Zealand and internationally. Over thirty in-depth semi-structured interviews were carried out with health, allied health and social service professionals in New Zealand. This data has been subjected to a thematic analysis that informs the scope of the research discussion, and provides the basis for my conclusions. Based on this data, my research suggests that professionals do indeed come into contact with cases of prenatal alcohol exposure in their work, and that many have developed innovative strategies for assisting individuals with confirmed or suspected FASD, but continue to face systemic and social barriers to achieving best practice in this area.

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  • Covariates in Pharmacometrics

    Lagishetty, Chakradhar (2013)

    Doctoral thesis
    University of Otago

    Understanding the variability in drug response forms an important aspect of pharmacometrics. Various biological, statistical, clinical and mathematical concepts need to be considered to reach a unified decision point to understand and quantify sources of variability. This current work involves studies on methodological and clinical exploratory evaluation of covariates in the context of pharmacometrics. Studies have been conducted using theoretic approaches on the design of pharmacokinetic (PK) studies for latent covariates, use of a reduction in random between subject variability as a covariate selection criterion and evaluated methods to handle non-ignorable nuisance covariates. Exploratory studies were also conducted in a clinical & experimental framework for identification of suitable metrics of organ function as covariates to predict drug clearance. Part I of this thesis includes methodological evaluation of covariates with Chapters 2, 3 and 4. Part II involves clinical exploratory evaluation of covariates with Chapters 5 and 6. Chapter 2 involved studies on the design of pharmacokinetic studies for latent covariates. The motivating context for this work was from a single nucleotide polymorphism (SNP) believed to influence clearance. This led to exploration of the concept of latent covariates which can have uncertainty in both their distribution and frequency. Simulation studies were conducted in both linear regression and nonlinear mixed effects modelling (NLMEM) frameworks assuming both even and uneven frequencies of the covariate. The designs for latent covariates were evaluated assuming continuous, ordinal and nominal distribution of covariates. Initially, the designs were evaluated in a theoretic framework using linear regression. Then, these were evaluated in a NLMEM framework assuming direct influence of latent covariate or indirect influence of latent covariate via another observable continuous covariate on parameter of interest. It was observed that continuous models performed better than categorical models. A covariate selection criterion was evaluated in Chapter 3. In pharmacometric analysis, a reduction in random between subject variability is used as part of standard criteria for selection of a covariate. The covariate is not selected if it failed to reduce random between subject variance (BSVR) in the model. Studies were conducted in a simulation framework to assess nested covariate models (NCM) and not nested covariate models (NNCM). Further, covariate-η interaction models were explored but were found to be marginally important. NCMs were found to be more robust to model misspecification than NNCMs which may not result in a reduction in BSVR. Chapter 4 explores analysis methods for handling nuisance covariates. The frequency with which a covariate occurs is important when interpreting its effect size. Covariates like genotypes and concomitant medication are sometimes present at low frequencies or as rare events. Due to alpha error inflation, estimates of their effect size may be false. These are termed nuisance covariates. If ignoring the covariate influences bias in parameter estimates then these covariates were considered non-ignorable. Simulation studies were conducted to assess various methods for dealing with nuisance and non-ignorable covariates. It was found that addition of a fixed effect parameter for the non-ignorable nuisance covariate handled it effectively but that this coefficient should not be used for inference purposes. The use of Box-Cox transformation of η and case deletion were considered but found to be less effective. Chapter 5 involved experimental work to quantify metrics of ageing. It is believed that variability would be better predicted with more reliable metrics of ageing such as biological age (BA) rather than chronological age (CA). It is proposed in this thesis that BA indices can be derived from the markers of ageing such as leucocyte telomere length (LTL) and/or its associated SNPs as modifiers on CA. A pilot study was conducted in healthy volunteers to obtain blood samples to collect DNA from young and older participants of either sex. An assay for LTL was implemented using a published qPCR assay and measured values of LTL in young and older subjects. SNP genotyping for selected SNPs was performed using Taqman® custom made probes. This chapter deals with the pilot clinical study and assay implementations. These assays were able to be implemented reliably so that they can be reasonably used for intended clinical exploratory studies. Initial findings found an association between LTL and CA that was similar to literature reports. Chapter 6 deals with evaluation of metrics of BA for predicting kidney function. Additional blood samples were procured from an on-going clinical study. This study included pharmacokinetic data on 51Cr-EDTA as a kidney filtration marker. Using a population pharmacokinetic approach the available BA metrics were evaluated to predict 51Cr-EDTA clearance. The BA markers were compared against CA and estimated creatinine clearance as negative and positive controls respectively for predicting kidney function. It was found that BA markers did not perform better than CA and both performed worse than estimated creatinine clearance as a covariate for 51Cr-EDTA clearance. So, to conclude, various methodological studies were performed which included design of studies for latent covariates, to assess BSVR as a covariate selection criterion and to assess methods for handling often missing and low frequency covariates as may be present in some genetic studies. In addition, these covariates were also considered and evaluated in a clinical study of ageing. Further work on covariates for estimating clearance changes due to ageing are required.

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  • Transgelin: Discovering its Role in Prostate Cancer Progression

    Samalia, Priya Darshni (2013)

    Doctoral thesis
    University of Otago

    Prostate cancer is the most commonly diagnosed cancer and the second highest cancer causing mortality amongst men in the Western world. The best possible prognosis for prostate cancer lies in early detection and therefore treatment of prostate cancer. Unfortunately, treatments are limited with significant associated morbidity. The need to develop better diagnostic and prognostic indicators and to identify new therapies are thus needed. Cancer causes disruption of cytoskeletal actin filaments and associated actin-binding proteins. Actin-binding proteins thus provide a potential diagnostic and therapeutic target. Transgelin is a 22 kD transformation and shape-change sensitive actin-binding protein, that forms actin cross-links which increase filament rigidity and bundle filaments into stress fibres. Using RT-PCR and Western blot analysis transgelin was shown to be expressed in non cancerous whole prostate tissue and in normal prostate epithelial cell isolates grown in culture conditions; transgelin was immunolocalised to both epithelial and stromal components of benign prostate tissue. Screening of cDNA libraries showed a significant downregulation of transgelin expression during prostate cancer progression. Transgelin expression was significantly downregulated in prostate cancer cell lines compared to normal prostate epithelial cells by real-time RT-PCR and Western blot. Transgelin expression was also reduced in clinical samples of prostate tissue compared to matched normal tissue by real-time RT-PCR. These results suggested a role of transgelin in the molecular regulation of prostate carcinogenesis and its potential role as a tumour suppressor. In order to elucidate the role of transgelin downregulation in the initiation of prostate carcinogenesis RNAi technology was employed. Functional inactivation of transgelin in normal prostate epithelial cells was achieved by designing siRNA duplexes targeted to transgelin mRNA. Prostate epithelial cells with at least a two-fold reduction in transgelin mRNA expression did not gain a proliferative advantage, anchorage-independent growth, increased wound healing ability or increased expression of MMP9 compared to control cells; suggesting that transgelin was not a key initiator of carcinogenesis. The TGF-β1 signaling pathway plays a tumour suppressive role in healthy prostate cells by the inhibition of cell proliferation and induction of apoptosis. As prostate cancer progresses prostate cancer cells become unresponsive to the tumour suppressive effects of TGF-β1. TGF-β1 therefore provides a putative anticancer target. Optimal TGF-β1 signaling requires an intact cytoskeleton for the recruitment of intracellular signal transduction of Smad proteins. Incubation of prostate epithelial cells with TGF-β1 induced transgelin expression. This response was attenuated in prostate cancer cell lines. These observations suggest that TGF-β1 maintains its own tumour suppressive properties by promoting a stable cytoskeleton. Additionally this response occurred independent of the Ras-MEK-ERK pathway. In conclusion, the work presented here provides evidence that transgelin expression is downregulated during prostate cancer progression. Transgelin downregulation may be an early event in the carcinogenic process however its loss alone is insufficient to invoke the hallmarks of cancer. Expression of transgelin is induced by incubation with TGF-β1 and this response is attenuated in prostate cancer cell lines. Transgelin is involved in the structural maintenance of the cytoskeleton as well as in signal transduction.

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  • Sonic hedgehog acts via Smoothened to stimulate neurite growth in gonadotropin-releasing hormone neurons

    Tan, Chew Ling (2013)

    Doctoral thesis
    University of Otago

    Gonadotropin-releasing hormone (GnRH) neurons are the central regulators of reproduction in vertebrates. GnRH cell bodies reside in the basal forebrain, and most extend long neurites in the caudal direction to terminate in the median eminence (ME) within the medial basal hypothalamus (MBH), the site of hormone secretion. Using immunohistochemistry, in vitro culture and in vivo genetic deletion strategies, my thesis investigated the role of a morphogen, Sonic Hedgehog (Shh) in the growth of GnRH neurites to the MBH across development. Dual label immunohistochemistry revealed that Shh was present in the basal forebrain, specifically in the preoptic area (POA), ventral hypothalamic neuroepithelium (VHN) and ventromedial hypothalamus (VMH) between embryonic day 14.5 (E14.5) and E16.5, when GnRH neurite extension is at its peak. At E14.5, both GnRH cell bodies and GnRH neurites were found to be within or close to the Shh-expressing domain in the basal forebrain. The coincidence of Shh and GnRH neurons in the basal forebrain suggests that Shh may signal to these embryonic GnRH neurons to regulate their development. To investigate this, a transgenic mouse line with the Shh receptor, Smoothened (Smo) deleted specifically from GnRH neurons (GnRH-Smo) was generated by using Cre-loxP technology. GnRH-Smo mice displayed normal GnRH cell body distributions, as there was no change in GnRH cell count or distribution pattern along the anterior- posterior or the medio-lateral axis in the basal forebrain between WT and KO mice. However, GnRH-Smo mice showed a significant decrease in GnRH innervation of the MBH at E18.5, but the innervation density was restored to WT levels by P0. This suggests that GnRH neurons suffer a delay in neurite growth when Shh/Smo signaling is abolished during their development. An acute brain slice preparation was adapted to examine the downstream signaling mechanisms by which Shh affects GnRH neurite growth. Preliminary data indicate that Shh activates the non-canonical pathway via phospho-activation of Src family kinase in developing GnRH neurons. This observation is consistent with a local role of Shh signaling in the growth of neurites, where it is envisioned that Shh acts via Smo to activate a Src-dependent signaling cascade to stimulate GnRH neurite growth. Finally, I tested the functional significance of the Smo-deletion-dependent perturbed GnRH neurite development on the activity of the GnRH neuronal network. Female GnRH-Smo mice underwent puberty despite an approximately 30% delay in GnRH innervation of the MBH during development. This is not surprising since GnRH innervation of MBH was restored by birth in GnRH-Smo KO mice and a previous study has shown that only ~25% of the normal number of GnRH neurons is sufficient to drive the reproduction axis. Taken together, the experiments performed for this thesis demonstrate that embryonic GnRH neurons use Shh for their development, and that Shh stimulates GnRH neurite growth by potentially acting through a non-canonical Shh signaling pathway. These studies provide further understanding of the molecular mechanisms by which GnRH nerve terminals arrive at the MBH, and identify an additional neuronal population whose neurites utilise Shh/Smo signaling for their development.

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  • The effect of anti-poverty and in-work tax credits for families on self-rated health in parents in New Zealand: A cohort study of 6,900 participants of the Survey of Family, Income and Employment

    Pega, Frank (2013)

    Doctoral thesis
    University of Otago

    Background Some social protection interventions are promoted as policy tools for addressing the social determinants of health to improve individual and population health and health equity. However, there is considerable controversy over whether publicly funded financial credits have a positive, a negative or no effect on health status in adults in high-income countries. Family Tax Credit (FTC) is a publicly funded financial credit intervention designed to increase income in families living in or at risk of poverty in New Zealand (anti-poverty intervention). In-work Tax Credit (IWTC) is a financial credit intervention that provides additional income to adults in families receiving social assistance (or in low-paid employment) for taking up (or staying in) paid employment (welfare-to-work intervention). This thesis estimates the effect of the FTC and IWTC interventions on self-rated health (SRH) in parents in New Zealand. Rather than analysing cross-sectional data, this thesis uses a cohort study design and fixed effects regression methods to better infer causal effects from observational data. Methods Seven waves of data (Waves 1 to 7, 2002-09) were extracted from the Survey of Family, Income and Employment (N = 29,790) and restricted to a balanced panel of working-age (19 to 64 years) parents in families over two or more consecutive waves (N = 6,900). Linear fixed effects regression analyses were conducted, estimating the association of change in FTC and IWTC with change in SRH at the individual level in the study sample over the short term. These analyses controlled for all time-invariant confounding and adjusted for measured time-varying potential confounding. The exposure variables were eligibility for FTC and IWTC and the amount of FTC and IWTC that the family of an eligible participant was entitled to. The outcome variable was SRH. Potential time-varying confounding variables were the equivalised gross total annual family income (minus FTC or IWTC), family type, number of dependent children in the family and employment status. Subsidiary analyses were conducted to estimate the effect of FTC and IWTC on SRH, where the outcome variable lagged behind the exposure variable by longer periods, and on two other health outcomes (psychological distress and current tobacco smoking), as well as to test for effect modification by ethnicity and level of income. Results The best estimate for a change in SRH one year after becoming eligible for FTC was a small, statistically non-significant increase of 0.013 in score over the short term [95% confidence interval (CI) -0.011 to 0.037]. An increase by $1,000 in FTC amount was also not associated with any discernible change in SRH (effect estimate -0.009, 95% CI -0.057 to 0.039). Likewise, neither becoming IWTC-eligible (effect estimate 0.003, 95% CI -0.020 to 0.027), nor an increase by $1,000 in IWTC amount (effect estimate 0.000, 95% CI -0.008 to 0.008) were associated with any discernible change in SRH. Subsidiary analyses also found no effect of FTC and IWTC eligibility and amount, when SRH lagged behind the exposure variables by a longer period. No effect of FTC and IWTC was found on the two other health outcomes, psychological distress and current tobacco smoking. Finally, no evidence for effect modification by ethnicity and level of income was found. Conclusions This thesis found no discernible effects of FTC or IWTC eligibility and amount on SRH at the individual level, over the short term. No previous studies have investigated the effect of anti-poverty tax credits on parental health. Five studies of welfare-to-work tax credits in the United States found no evidence for an effect of these credits on health status, except for inconclusive evidence on smoking favouring a reduction. This previous evidence for the United States was generally consistent with the finding from this thesis for New Zealand. Strengths of this thesis include its relatively good classification and measurement of the exposure variables and strong control of confounding. Limitations included some risk of bias from misclassification and mismeasurement of the exposure, outcome and confounding variables, likely towards a null finding. The internal validity of the study was judged to be strong, but the thesis had risk of bias from misclassification of the exposure. This study cautions health sector policy makers against investing in anti-poverty and welfare-to-work financial credit interventions to improve adult general health status and health equity in New Zealand and comparable high-income countries. Future research should investigate the effect of FTC and IWTC over the longer term, including the effect of a regime of treatment with FTC and IWTC over several consecutive waves.

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  • Momentum Trading Strategies in Financial Markets

    Tajaddini, Reza (2013)

    Doctoral thesis
    University of Otago

    My thesis consists of three essays investigating sources of profits to price momentum and related trading strategies in financial markets. Although each essay can stand independently, the methods used in them overlap and their concepts are closely interrelated. My first essay (Chapter 2) examines price momentum in emerging currency markets. I find that long-short momentum strategies gain about 1–3% per annum after actual transaction costs. These results are similar to, but more volatile than, those already published for major currencies. My findings contrast starkly with those of the only other comprehensive paper published in the very limited literature in this area. Contrary to published results in major currencies, I find that emerging market currency momentum strategies typically borrow in high interest rate currencies and invest in low interest rate currencies. Also, as the domestic interest rates of the base currency rise in the cross section, momentum profits fall and the return attribution shifts from the short position to the long position. My second essay (Chapter 3) examines price and earnings momentum in the New Zealand stock market, with careful attention paid to the crisis period and to transaction costs. A feature of this study is the first application of a realistic practitioner trading technique to combined momentum strategies. I am the first to look at the interrelationship between fund size, turnover, trading frequency, and exposure to ex-ante alphas in this context. My results confirm the existence of both price and earnings momentum in the New Zealand equity market. The best strategy I find outperforms the benchmark by 100 basis points per annum after a careful consideration of transaction costs. Although the 2007–2009 crisis significantly increased transaction costs in general, the earnings momentum strategy and the combined momentum strategies perform better net of transaction costs during this period than during the non-crisis periods. This unexpected result is explained by lower turnover of the momentum strategies during the crisis period leading, in turn, to lower transaction costs and also (I hypothesize) better performance of the earnings momentum strategy during periods of increased information uncertainty. My third essay (Chapter 4) brings together the ideas in the first two essays and introduces a new post-macroeconomic-announcement drift (POMAD) trading strategy in currencies—analogous to the well-known post-earnings-announcement drift in equities. Although the POMAD strategies are profitable on average over the entire sample, and price momentum strategies are generally unprofitable on average, I show that price momentum profits are related to POMAD profits in the major currency markets. I find that profits to both POMAD and price momentum strategies are time varying, that the full impact of news is incorporated only slowly into currency prices, and that price momentum and my POMAD trading strategies are all profitable in major currencies during the recent crisis period. Among my macroeconomic variables, the consumer price index is the least influential variable, while industrial production, trade balances, and the unemployment rate are the most influential.

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  • The Antitumour Properties of Endophytic Fungi from Marine Plants in Malaysia

    Ariffin, Siti Alwani (2013)

    Doctoral thesis
    University of Otago

    Endophytes from marine plants have not been widely explored, and their bioactive compounds have not been well documented. In the present study, 64 endophytic fungi were isolated from 2 Malaysian marine plants (Pandanus odoratissimus and Nypa fruticans) and 6 seaweed species (Turbinaria conoides, Caulerpa lentifera, Caulerpa racemosa, Padina australis, a variant of Caulerpa racemosa, and Sargassum oligocystum). The endophytic extracts were tested for their cytotoxic activity against seven human cancer cell lines. Out of the 64 extracts tested, 49 (77%) of them were able to inhibit cancer cell lines. Eight of the endophytic extracts that were potent (IC50 = ≤0.1 µg ml-1) against colon (DLD-1) and lung (NCI-H1299) cancer cell lines were further tested for their effects on a normal human fibroblast (D551) and liver (WRL-68) cell lines. Cytotoxic effects were not observed in these latter two cell lines. Among the 8 active extracts, 3 (S1, S2 and P12) with significant traces of metabolites were selected for identification of the bioactive compounds using a dereplication technology. Consequently, 3 known and 12 unknown compounds were determined using the rapid technique. The structures were elucidated by 1H NMR and confirmed by x-ray crystallographic data. Of the known compounds, S1-1 was a monoclinic red crystal, P12-1 was a monoclinic yellow crystal and compound P12-2 was a pale yellow amorphous product. They were identified as bostrycin (S1-1), globosuxanthone A (P12-1) and 1-hydroxy-2 methylanthraquinone (P12-2). Bostrycin and globosuxanthone A exhibited moderate cytotoxicity against colon cancer cell line (IC50 0.9 and 3.25 μg ml-1) and lung cancer cell line(IC50 2.5 and 2.3 μg ml-1 respectively). However, 1-hydroxy-2 methylanthraquinone was not active against the tested cancer lines. This is the first report on globosuxanthone A being isolated from a marine endophytic fungus. The twelve unknown compounds from extract S2 displayed peptidic characteristics such as an α proton signal and a huge molecular weight (1012-1950 Da) but remain unidentified. The structures of the active compounds in S2 extract which are responsible for the bioactivity therefore are not able to be elucidated. The sequence analysis of internal transcribed spacers ITS1 and ITS4, and phylogenetic analysis identified the three isolates to be ascomycetes designated as Phomopsis sp (S1) and Hypocrea jecorinasp (S2 and P12). Further examination focussed on the molecular mechanism of action of the endophytic extract S2. Extract S2 induced apoptosis in colon cancer cells (DLD-1 and HCT 116) through an extrinsic pathway and was activated by the caspase 3 and 8 cascade. The activation of caspases 3 and 8 were further confirmed with the use of the generic caspase inhibitors Z-VAD-FMK, Z-DEVD-FMK and Z-IETD-FMK. Co-incubation of inhibitors with treated cells significantly (p0.05) in the body and organ weights between the control and the treated group was observed. Pathologically, neither gross abnormalities nor histopathological (HE staining) changes were observed in liver. Haematological analysis and clinical blood chemistry revealed no toxic effects of the extract. The level of total cholesterol in treated males with 100 and 400 mg kg-1 significantly (p<0.05) antioxidant activity through increased levels of superoxide dismutase (SOD) and glutathione peroxidase (GPX) enzymes in serum, liver and kidney. The research findings from the present study show the potential of natural marine products particularly in Malaysia as a source of new and novel therapeutic entities. Marine endophytic fungi could be a good potential source of anticancer drugs as several can provide extracts that are potent and safe, thus deserving further extensive investigation.

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  • Sock fabrics: The effect of fibre type, yarn type and fabric structure on selected properties

    Van Amber, Rebecca Ruth (2013)

    Doctoral thesis
    University of Otago

    Socks are garments which contribute to maintaining the thermal neutrality of the foot, protecting it from blisters, and providing a cushion to absorb energy due to frequent impact. Properties of socks have been investigated previously, most often for comfort, sport or military purposes. The type of fibre used in socks has been a focal point, with differences detected in properties often attributed to the superior characteristics of one fibre type over another. The focus on fibre type has been such that the effects of other sock components (e.g. yarn and fabric structure) have often been overlooked. One reason the effect of fibre type, yarn structure and fabric structure on sock properties is not fully understood is due to the design of experiments which are such to preclude these characteristics to be separated from one another. The difference between this study and previous work is the use of sock fabrics where the manufacturing has been carefully controlled, ensuring that only the variables of interest differ among the fabrics. Three common fibre types (acrylic, fine wool, mid micron wool), yarn structures (single ply, high-twist, low-twist) and fabric structures (single jersey, half-terry, terry) were selected as variables, and the 3 x 3 x 3 experimental design resulted in 27 sock fabrics. Thus, the aim of this thesis was to investigate the effect of fibre type, yarn structure and fabric structure on thermal and moisture properties, frictional properties, compression and recovery from compression of sock fabrics. Standard test methods were used where appropriate. Frictional properties and compression were determined using adapted versions of methods previously reported. Fabric structure dominated most selected properties, with terry fabrics being thickest, most thermally resistant when dry, most absorbent, most resistant to water vapour transfer and most conductive to heat transfer when damp. Single jersey fabrics had the lowest coefficient of static and dynamic friction, half-terry had the highest. Half-terry fabrics retained the greatest percentage of their original thickness during compression, however single jersey fabrics had the best compression to recovery ratio. When the amount of energy absorbed was standardised for fabric thickness, only the number of compression cycles and whether the fabric was dry or damp had measurable effects. Dry fabrics had a better compression to recovery ratio and absorbed more energy than damp fabrics. Friction between fabric and a synthetic skin was affected most by the applied load, with a higher load resulting in a greater frictional force, and higher coefficients of static and dynamic friction. The overall effect of yarn on properties was less than fabric structure, with small but significant effects on the coefficient of static friction, compression to recovery ratio, thermal resistance and liquid absorption capacity. The effect of fibre type was also minimal, with differences detected among fibre types typically less than differences detected among the fabric structures. The most important effect of fibre was on the static frictional force and coefficient of static friction of damp fabrics, with fabrics composed of fine wool exhibiting lowest friction, and acrylic fabrics the highest.

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  • Magnesium as a biomaterial: Calcium phosphate coatings for corrosion control

    Shadanbaz, Shaylin (2013)

    Doctoral thesis
    University of Otago

    Magnesium (Mg) was originally developed as a degradable metallic biomaterial for orthopaedic application in the mid 1800s. The theory behind the use of a biodegradable metal is that it would allow the complete elimination of the orthopaedic device after healing, removing the need for a second surgery for implant removal. Additionally, Mg exhibits a high strength to weight ratio and an elastic modulus similar to bone, which are favourable characteristics for optimal fracture fixation and healing. These properties also minimise complications such as stress shielding and the resultant osteopenia. Although, investigations of Mg as orthopaedic implants were hindered by its highly reactive nature and unpredictable corrosive behaviour. However, recent technological advancements in the processing, manufacture, and modification of Mg have warranted renewed interest in Mg as a biomaterial. The main focus of this study is using a novel coating method to control Mg corrosion, whilst maintaining or improving the biocompatibility of the material. To address this aim, the calcium phosphates (CaP), brushite and monetite, were developed as coatings on Mg. These coatings were then assessed both in vitro and in vivo for corrosion and biocompatibility . The initial investigations were carried out using in vitro techniques to assess the suitability of these coatings for advancement to in vivo assessment. Both the brushite and monetite coating showed corrosion protection in a range of physiological solutions exhibiting mass loss ranges of 4.39-6.39% and 2.76- 4.39% respectively over 28 days compared to the uncoated range of 5.1%- 10.1%. In vitro biocompatibility tests using a murine fibroblastic cell line (L929) and a human osteosarcoma cell line (SaOS-2) assessed the proliferation/viability of cells on the coatings using a standard LIVE/DEAD® assay. Western blotting was also used to identify the bone markers, osteopontin, osteonectin, osteocalcin, and bone-sialo protein. ALP activity was also used to assess the osteopotentive properties of the coatings. The results indicated good biocompatibility for both the brushite and monetite coatings when compared to uncoated Mg and inert titanium. The in vitro findings supported the further investigation of the coatings in an in vivo environment. Accordingly, a small animal model, the Lewis rat, was selected for preliminary corrosion and biocompatibility investigation in a subcutaneous environment. In these investigations, the brushite- and monetite-coated Mg displayed enhanced corrosion protection compared to an uncoated control, more so in the case of the latter coating. The range of mass loss seen between uncoated, brushite and monetite coated were 2.46-7.11%, 1.89-5.14% and 1.42-3.78% respectively. No differences were seen in the inflammatory responses to coated Mg samples when compared to uncoated samples, supporting their biocompatibility in an in vivo location. The corrosion and biocompatibility data further validated the exploration of these coatings in a bony location in a larger animal model. Accordingly, the Romney-Cross sheep was selected for the evaluation of brushite and monetite coatings in both cortical and cancellous bone. The data obtained was conflicting and provided varied support for the use of brushite and monetite coatings for fracture fixation applications. The coatings, when compared to uncoated controls, provided no significant corrosion protection in cancellous bone although some initial protection was apparent in a cortical location. Moreover, the biocompatibility of the coated Mg paralleled the uncoated controls. However, the relationships between the assessed parameters (corrosion, bone-implant contact, bone deposition, and hydrogen production) suggest and support the further consideration of these coatings for fracture fixation applications.

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  • The Mission of the Triune God: Trinitarian Missiology in the Tradition of Lesslie Newbigin

    Dodds, Adam (2013)

    Doctoral thesis
    University of Otago

    In this thesis I investigate trinitarian missiology in the tradition of Lesslie Newbigin. As one of the most important missiologists of the twentieth century, Newbigin is well known for being a successful missionary to India and for catalysing missionary engagement with modern Western culture. Theologically, Newbigin is also significant for pioneering a trinitarian missiology. It has been fifty years since Newbigin called for the development of an explicitly trinitarian missiology, and this work is a response to that call. As a theologian and missiologist, Newbigin’s chief contribution was not in systematically expositing a topic, but in prophetically discerning the ‘signs of the times’ in order to chart a course forward. Consequently, I set out to examine Newbigin’s trinitarian missiology, and then I go beyond Newbigin to construct a systematic theological trinitarian missiology. Thus, this study falls neatly into two Parts. Part One examines the main contours of Newbigin’s missiology from his mission to India (chapter one) and his mission to modernity (chapter two). Then in chapter three I examine in detail Newbigin’s trinitarian missiology in Trinitarian Doctrine for Today’s Mission and The Open Secret, noting the influences on Newbigin, the historical development in his thought and the content of his account of the mission of the Triune God. Part One forms the foundation for Part Two. In Part Two I develop a constructive and systematic trinitarian missiology that builds on Newbigin’s trinitarian missiology presented in Part One. I first focus on the doctrine of the Trinity proper and its relevance for the theology of mission by discussing the Triune being of the missionary God (chapter four). Mission originates in the Triune being of God, the being that is constituted in a communion of loving relations. As love is not incidental but intrinsic to who God is, so mission ad extra flows freely out of God’s trinitarian being. God is a missionary God. In chapter five I develop an explicitly trinitarian account of the mission of the Son and the mission of the Holy Spirit, examining the central features of their respective missions in relation to each other and in relation to the missio ecclesiae. God seeks communion with His wayward creation and establishes in Christ by the Spirit a living echo of that divine communion: the Church. In chapter six I develop a trinitarian account of the missionary Church and the Church’s mission. The Church exists in Christ, by the Spirit, for the Father. She is constituted in and by God’s mission, being Christologically and Pneumatologically determined. Consequently, the Church is missionary by nature. There is a missionary dimension to all she does, and she possesses a call to intentional missionary activity: communicating the gospel to the ends of the earth. Finally, I will offer a conclusion summarising the contribution of this thesis and indicating how further work in trinitarian missiology might proceed (chapter seven). In this thesis I intend to provide a systematic account of the central features of the mission of the Triune God in the tradition of Lesslie Newbigin. In doing so I will demonstrate the necessity of a Christian missiology being thoroughly trinitarian, and the abiding significance of Newbigin’s writings for continued missiological reflection for the purpose of serving the call of the Church to mission.

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  • Soldiers' Foodways: Historical Archaeology of Military Comestibles in the Waikato Campaign of the New Zealand Wars

    Simmons, Alexandra Lee (2013)

    Doctoral thesis
    University of Otago

    Food is an essential part of human existence and directly linked to the cultural behaviour of individuals, groups, and institutions. In their commentary on food studies, Mintz and Du Bois (2002, p. 8) noted that war has been relatively neglected as a research focus. This thesis investigates British and colonial soldiers’ comestibles during the Waikato campaign of the New Zealand Wars, a regional conflict that commenced in 1863. It is the first major investigation that has been carried out on this subject in New Zealand and one of the few investigations worldwide on soldiers’ comestibles during a war. The thesis addressed three questions: what did soldiers eat and drink during the campaign; how was food security ensured; and what foodways practices indicated status. The questions address themes that are at the core of foodways research (Dery 1997, Bray 2003, Cool 2006, Andersen and Moltsen 2007, Peres 2008, and Eichelberger 2010). Food security was of specific interest because the Waikato campaign followed the disastrous Crimean War and took place during a time of British military supply system reform. Cognitive archaeology and middle-range theory guided the research process. A middle-range methodological approach was used to address the research questions in three distinct data sources—the official records, eyewitness accounts, and the archaeological record. Each source was compiled as an independent record of comestibles using the same criteria; a middle-range technique used by Binford (1987), Leonie and Crosby (1987), Leonie and Potter (1988) and Smith (1996). The criteria were based on underlying food culture rule sets (Leach 2008, 2010). The rule sets were modified and used to construct a food culture research framework that addressed the range of data available in the sources. The framework structured the investigation. Among the findings was evidence that the War Office supply and transportation system reforms had little impact on food systems during the campaign in New Zealand. More unusual findings included the link between food security and luxury foods (a finding not identified in the military food research of Dery 1997, Cool 2006, or Eichelberger 2010). The research also indicated a variety of food practices were used to indicate status. Many of the foodways were embodied in the mess system—a system of hierarchal separation. For example, the mess building or tent was a daily visual reminder of the military hierarchy, e.g. commissioned officers’ messes, sergeants’ messes, enlisted men’s messes. Military hierarchy is directly linked to military control and discipline. The ideas and hypotheses presented are pertinent to future archaeological investigations at military sites in New Zealand and overseas. The research methodology and the foodways research framework also have applications for comestible research at other sites such as railway camps, abandoned towns, mining camps, as well as for regional analysis of foodways at contemporary pre-historic sites.

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