12,490 results for Doctoral

  • Aspects of the population biology and ecology of the New Zealand cancer crab, Cancer novaezelandiae (Jacquinot, 1853) :

    Chatterton, Thomas David (1990)

    Doctoral thesis
    University of Otago

    190 leaves :ill. ; 30 cm. Includes bibliographical references. University of Otago department: Zoology

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  • The transformation of Alexander's court : the kingship, royal insignia and eastern court personnel of Alexander the Great

    Collins, Andrew William (2008)

    Doctoral thesis
    University of Otago

    x, 272 leaves ; 30 cm. Includes bibliographical references. University of Otago department: Classics.

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  • Microstructural evolution under non-steady state deformation in mid-crustal ductile shear zones

    Cross, Andrew James (2015)

    Doctoral thesis
    University of Otago

    Ductile shear zones localise tectonic stresses and accommodate plate motions in the middle to lower crust and mantle, and control the strength of much of the Earth. Despite a common assumption that ductile shear zones deform under nominally steady-state conditions, changes in stress and strain rate are anticipated during shear zone formation and localisation, and in mid-crustal shear zones which are periodically loaded from above by earthquakes. Here, the microstructural response to changes in stress and strain rate is explored with particular emphasis on the evolution of grain size, crystallographic fabric and dominant deformation mechanism. A broad range of techniques have been applied, including electron backscatter diffraction (EBSD), titanium-in-quartz (TitaniQ) thermobarometry, numerical modelling of grain size evolution and Griggs apparatus experimentation. For context, quartzofeldspathic mylonites of the Alpine Fault zone (AFZ) of New Zealand have been studied and are used to relate numerical and laboratory studies to nature. During shear around rigid garnet porphyroclasts, quartz in the AFZ mylonites undergoes grain size reduction by dynamic recrystallisation in response to increasing stresses and strain rates adjacent to a porphyroclast. Meanwhile, quartz [c]-axes reveal increasing amounts of slip on rhomb and prism planes. These results are replicated in the laboratory by shear of quartz around alumina piston asperities, during which prismslip becomes dominant and resistant to subsequent replacement as stresses reduce. Recrystallised quartz grain sizes in the AFZ mylonites are consistent with differential stresses of ~50 MPa, which are well replicated by finite element models using quartz rheological data. Quartz deformation in the AFZ mylonites ceased at around 500_C, as recorded by the preservation of grain boundary migration microstructures and titanium-in-quartz concentrations, which appear well equilibrated due to rapid grain boundary migration during deformation. Rates of grain size increase downshear of garnet porphyroclasts far exceed laboratory-measured rates of static annealing. This discrepancy probably reflects the additional contribution of internal strain-energy driven grain boundary migration to surface-energy driven grain growth, enhancing grain growth rates in favourably oriented grains at the expense and ‘elimination’ of unfavourably oriented grains. In experiments simulating rapid strain rate changes analogous to mid-crustal seismic stress cycling, plagioclase aggregates undergo rapid dynamic recrystallisation during a strain rate increase, and are remain weakened long after strain rates and stresses return to ambient levels. The longevity and degree of mechanical weakening depend on the rate of grain growth to re-establish steady-state conditions, and the dominant deformation mechanism. If dislocation creep is dominant throughout a strain rate perturbation, no mechanical weakening is observed. However, if grain size sensitive processes of diffusion creep and grain boundary sliding dominate, mechanical weakening is achieved. Grain size reduction in response to a stress increase is inferred to cause weakening of a crystallographic fabric through enhanced grain boundary sliding, though fabric weakening appears slow. In numerical models of grain growth during a postseismic stress and strain rate drop, rapid rates of grain growth are required to re-establish microstructural steady-state conditions on timescales equivalent to typical earthquake recurrence intervals. Despite this, dynamic grain growth rates calculated for natural AFZ quartz are sufficiently rapid to allow at least a partial return to steady-state during a typical 300-year AFZ interseismic period.

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  • Let the "Dirty" Women Speak: The Agency and Divergent Aspirations of Devadasis and Development Interventions in Karnataka, India

    Aaron, Nicole (2015)

    Doctoral thesis
    University of Otago

    In this dissertation, I examine the relationships between development organisations and religious beneficiaries through an ethnographic exploration of devadasi women in rural North Karnataka, India. Contemporary devadasis are both religious and poor. As Hindu, Dalit women, they are dedicated to the goddess Yellamma by their mothers, and practice sex work to support themselves economically. Their histories are bound up in colonial interventions and reform movements, but their pre-colonial histories are largely unknown. The early twentieth-century saw a rise in debates around the “woman question”, largely centred on “respectability” and “morality”, which had significant consequences for devadasis, who were slowly forced out of the temples, where they are said to have once acted as priestesses. The process of this transition out of the temples is unclear, but today’s devadasis are seen by NGOs and reformers to be nothing more than prostitutes—understood to be “dirty” women lacking respect. Since 1982, the devadasi practice has been criminalised in Karnataka, and the government has implemented reform and rehabilitation schemes purportedly to help the women out of sex work. Additionally, the rise in HIV/AIDS amongst the group has led to an increase in development interventions, seeking to mitigate both HIV/AIDS and poverty. Through the influence of these reform and development interventions, I argue that the devadasi practice is changing, and the women’s identities are changing. Utilising life stories of devadasis, interviews with staff of development organisations, focus groups between the two, and participant observation over the course of twelve months, this thesis seeks to reveal how devadasi women use their new identities to negotiate poverty with the organisations trying to help them. I argue that, while these new identities have previously been portrayed negatively, we may detect the agency of devadasis in the various narratives they use to get what they need from these organisations. Moreover, while these organisations advance their own religious beliefs onto the devadasis, the religious importance of the devadasi practice continues to be seen as irrelevant and/or superstitious. The findings from this research indicate that development organisations are patronising towards devadasis and uninterested in listening to them. Consequently, I demonstrate that divergent aspirations emerge between development interventions and what devadasis express as their needs, which prevents interventions from being effective in this context. Development organisations do not tend to consider devadasi paddhati (tradition) in development interventions. This research contributes to existing scholarship in religion and development, through an analysis of the divergent aspirations that exist between religious beneficiaries and development interventions. Using postfeminist theory, I explore alternative conceptions of agency, which recognise the difference that exists between devadasis and their desires. I also examine how postdevelopment theory provides a space for understanding the place of religion in development and focuses on agency and subjectivity as priorities when carrying out development interventions. In doing so, I employ a method of “speaking with” (Nagar and Geiger 2007) devadasis to argue that devadasis display agency through speech, where they are able to negotiate poverty. Depending on their particular needs and their assessment of their most beneficial course of action, they will choose either to express their exploitation or to boast of their empowerment.

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  • An investigation of droplet evaporation characteristics in an ultrasound environment

    Protheroe, Michael Desmond

    Doctoral thesis
    Auckland University of Technology

    This study investigates and quantifies the effect of an imposed ultrasound field on the evaporation of water droplets in, for example, humidifiers used in medical respiratory treatments. The purpose of the ultrasound field is to accelerate the droplet evaporation process. This would have benefits in terms of improved efficiencies, more compact equipment sizes and better process controllability. A preliminary investigation was carried out to identify the most promising mechanisms for the effect of the imposed ultrasound field on the evaporating droplets – this being the enhancement of the normal mass and heat transfer processes involved. From this, theoretical models of normal and ultrasound enhanced droplet evaporation were developed to predict the rates of water evaporation and also changes to the droplet size distribution during evaporation. An experimental investigation was carried out to measure water droplet evaporation rates and changes to the droplet size distribution under normal and ultrasound enhanced conditions. It was found that the ultrasound field improved droplet evaporation rates in all cases tested, even at very low power levels. Improvements varied from 1 – 30%. An increase in the strength of the ultrasound field increased the improvement in evaporation rate. However, air flow above a certain threshold diminished this improvement by disrupting the ultrasound field. Investigation of the changes to the droplet size distribution indicated that at high ultrasound power levels and low air flow rates a significant amount of droplet coalescence occurred which caused the droplet distribution for the remaining droplets to shift to much larger droplet sizes. Results from theoretical models compared well to the experimental results for most experimental conditions. Differences between model and experiment occurred for the very small droplet sizes and where the effect of the ultrasound field caused maximum droplet coalescence and heating of the air and these areas warrant further future investigation. It was concluded that the ultrasound enhancement of water droplet evaporation does occur by enhancing the heat and mass transfer processes involved, that improvements in evaporation rate up to 30% could be achieved and that this could be applied to medical respiratory equipment to improve its operation and efficiency.

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  • Participation, urbanism and power

    Bond, Sophie (2007)

    Doctoral thesis
    University of Otago

    xiii, 312 leaves :ill. ; 30 cm. Includes bibliographical references. "July 2007". University of Otago department: Geography.

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  • An examination of East Polynesian population history

    Chapman, Patrick Maurice (1998)

    Doctoral thesis
    University of Otago

    xii, 252 p. :ill., maps ; 30 cm. Includes bibliographical references. "March 1998." University of Otago department: Anthropology.

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  • Teachers and dance in the classroom : So, do I need my tutu?

    Buck, Ralph (2003)

    Doctoral thesis
    University of Otago

    [x], 350 leaves :ill., maps ; 30 cm. Includes bibliographical references. University of Otago department: Education. "21 July 2003"

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  • The efficiency of adaptive cluster sampling

    Brown, Jennifer A. (1996)

    Doctoral thesis
    University of Otago

    xiii, 197 leaves :ill. ; 30 cm. Includes bibliographical references. University of Otago department: Mathematics and Statistics. "January 1996."

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  • Who is God for us? : images of God in a group of Roman Catholic lay women in Aotearoa New Zealand

    Betz, Mary Agnes Ann (2003)

    Doctoral thesis
    University of Otago

    xix, 317 leaves :ill. (some col.), maps ; 30 cm. Includes bibliographical references. University of Otago department: Theology and Religious Studies. "28 November 2003"

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  • Role of iron, siderophores and iron regulation in the Epichloё festucae - Lolium perenne symbiosis

    Forester, Natasha Talei (2015)

    Doctoral thesis
    University of Otago

    Ferric iron-chelating siderophores are produced by microorganisms to compete for and sequester iron, an essential but potentially toxic micronutrient. Epichloё festucae, a filamentous fungus that is mutualistically associated with the grass Lolium perenne, occupies apoplastic spaces between the plant’s shoot cells and relies upon host nutrients to survive. E. festucae synthesises two siderophores, epichloënin A and ferricrocin (FC). A non-ribosomal peptide synthetase SidN was previously found to be required for the biosynthesis of epichloënin A, for iron uptake, for normal colony growth under iron-starved conditions and for normal mutualistic associations of E. festucae with L. perenne. Little else is known about the mechanisms governing iron metabolism in E. festucae or the role of iron in maintaining E. festucae - grass associations. To explore siderophore biosynthesis and iron regulation in E. festucae, iron-related genes were identified and fungal mutants were generated. These mutants, deficient in either siderophore biosynthesis (ΔsidA, ΔsidC, and ΔsidN) or iron regulation (ΔsreA and ΔhapX) were characterised and their phenotypes analysed in culture and in planta. The sidA gene encodes the L-ornithine-N5-oxygenase SidA, an enzyme shown to be required for the biosynthesis of both siderophores. The sidC gene encodes an NRPS enzyme, SidC that assembles FC, a siderophore that was only found in mycelial fractions. Mass spectrometry data indicated that epichloënin A and FC are synthesised under low and high iron availabilities, respectively. Intriguingly, the findings of significant quantities of epichloënin A in mycelial fractions of the wild-type strain Fl1 (WT), combined with the observation that ΔsidN colonies lacked iron-dependent pigmentation suggested that epichloënin A functions in intracellular iron management, in addition to extracellular iron uptake. In the presence of iron, increased ferricrocin production and vacuolar-iron uptake occurred in ΔsidN compared to WT cultures, suggesting an increased intracellular iron pool in the ΔsidN colonies that might fuel the observed increase in aerial hyphal growth. Iron starvation impaired growth of all siderophore mutants in culture, but could be repaired by supplementing iron-deprived media with FC, which was shown to be required for aerial hyphal growth. Iron-bound ferriepichloënin A could not recompense for the loss of FC, and repressed ΔsidN colony growth in excess, suggesting that epichloënin A modulates iron accessibility intracellularly. The ΔsidN fungi grew profusely in hosts around meristematic tissues and correlated with a host-stunting phenotype, which could only be induced by loss of SidN (and epichloënin). These results suggest interplay between siderophores in moderating in planta fungal growth, which might prevent over-colonisation of important host organs such as meristems whose development affect plant architecture. The sreA and hapX genes encode two iron-responsive transcription factors that are involved in regulating iron homeostasis in E. festucae under iron-sufficient and -deficient conditions, respectively. Gene expression analyses showed an iron-dependent mutual control mechanism exists between SreA and HapX, and an alternative splicing mechanism may control SreA activity. Loss of SreA resulted in growth defects and de-repression of siderophore biosynthesis in the presence of iron, while loss of HapX raised FC levels during iron deficiency indicating repressor functions of these proteins. Associations of regulatory mutants with L. perenne were not stably maintained long term and hyphae displayed atypical morphology. The ΔsreA fungi could induce chlorosis during low iron supply to host plants indicating that ΔsreA mutants compete with the host for iron. E. festucae appears to have a tightly regulated iron management system for balancing growth and survival, preventing over-competition for iron in the intercellular niche thus promoting mutualistic associations. Mutations that interfere with Epichloë iron management negatively impact iron-dependent fungal growth and can destabilise mutualistic plant - fungal associations to the detriment of either symbiotic partner.

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  • Exploring the development of biological literacy in Tanzanian junior secondary school students

    Juma, Zawadi Richard (2015)

    Doctoral thesis
    Victoria University of Wellington

    Internationally, scientific literacy is a major goal of science education in the twenty first century. In Tanzania, where there is a widespread lack of public understanding about major health issues, biological literacy is needed so that people can make decisions about the socio-scientific issues that confront them. To that end, the Tanzanian school curriculum aims to connect students’ understandings of Biology to their everyday lives but few studies have been conducted that show whether these aims have been achieved, especially in junior secondary school. This ethnographic case study investigates the ways in which the junior secondary school Biology curriculum in Tanzania supports or constrains the development of biological literacy and how institutional context, particularly as it relates to urban and rural schools, influences the delivery of the Biology curriculum. Teachers’ and Year Four students’ of secondary schools views about school Biology were sought in the course of this study and the issues that emerged were analysed using social constructivist and social constructionist theoretical frameworks. Data were collected through student questionnaires, student focus group interviews, teacher interviews, and classroom observations. The research sites included rural and urban schools, and government and private schools. The findings suggest that the Biology curriculum and the ways it is delivered do not adequately address the students’ needs and therefore is unlikely to enable them to become biologically literate. Rural schools are less well equipped than urban schools to deliver the curriculum and teachers and students face bigger challenges. A key finding was that Tanzanian young people have a strong desire to learn more about reproductive Biology and health issues but these are not prioritised in the current curriculum. In light of these findings, curriculum changes are recommended to provide learning opportunities for students to gain biological knowledge and skills that are relevant to their daily lives.

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  • Family Language Policies of Refugees: Ethiopians and Colombians in New Zealand

    Revis, Melanie Sandra (2015)

    Doctoral thesis
    Victoria University of Wellington

    There has been a surprising dearth of research on language maintenance and shift in New Zealand over the last decade. This thesis addresses this gap by examining incipient patterns of language maintenance and shift in families in two refugee communities in Wellington. Earlier research suggests that immigrants may maintain their ethnic languages in spite of societal factors pressuring language shift for up to three generations. By then, however, language shift is often completed, with the third generation using the majority language only (Fishman 1991). In a largely monolingual country such as New Zealand, this shift may be accomplished in only two generations (Holmes et al. 1993). Understanding the language dynamics at the micro level that eventually lead to language maintenance or shift requires more research into actual language use among family members than traditional methods provide. This investigation therefore uses ethnographic observations, semi-structured interviews and recordings of naturally-occurring interactions between mothers and their children to highlight the challenges involved in transmitting a minority language. Using Spolsky’s (2004) tripartite model of language policy, I investigate family language beliefs, practices, and management in the refugee-background Ethiopian and Colombian communities. The Amharic-speaking Ethiopian community consists mostly of first and second generation members. They first settled in New Zealand in the 1990s and now display awareness of the challenges of maintaining their language. Most Ethiopian parents consider it their responsibility to teach their children Amharic in the home and many have introduced explicit language policies to promote Amharic use. These families exhibit an ‘impact belief’ (De Houwer 1999) which links their positive beliefs about Amharic with their management of family language practices. Nevertheless, in some cases children subvert and contest explicit language management and become primary agents of language shift. Supporting the parents’ efforts, the Ethiopian Orthodox Church provides a social space where Amharic may be used backed by an explicit policy which requires all members to use the language when at church. This policy provides valuable institutional support and cultural capital for Amharic and contributes to the vitality of the language in Wellington. The Colombian community has had a relatively shorter stay in Wellington, with the first members arriving as recently as 2008. Colombian mothers want to transmit Spanish and many seem confident that their children will maintain the language. In particular, they consider the Colombian variety of Spanish to be a source of pride and a core value (Smolicz 1992), as many participants closely link this variety to their Colombian identity. They further capitalise on the prestige of Spanish as a world language that motivates them to use it even outside their ethnic community. However, few families have put in place explicit language policies to use Spanish in the home; instead, many regard it as a more urgent concern that their children learn English. Overall, despite the community members’ positive attitudes towards their ethnic languages, their efforts to transmit these languages appear to be constrained by the fact that English is invested with considerable cultural capital (Bourdieu 1977) in New Zealand. English acquisition often takes priority, particularly for many newly arrived Colombian families. The participants’ refugee experiences, length of residence in New Zealand and the societal status of their ethnic languages seem influential factors on the degree of control they assume over their children’s language practices. Families also dynamically adapt their language policies to the circumstances, for example by introducing an explicit minority language policy after their children have acquired what they consider to be enough English. Despite a strong desire for their children to continue speaking the ethnic language, the parents have many other (non-linguistic) responsibilities and they frequently lack knowledge about “success strategies” for minority language transmission. Moreover, the children often take significant agency by introducing English into the home domain, in some cases even influencing other family members to use it, and thus initiating language shift. The detailed interactional data in this research provides insight into the different ways parents have instantiated their varying language policies and negotiated home language choice with their children. In sum, this research provides insight into language transmission efforts at the family level, and, using data from observations, interviews and recordings of mother-child interaction, describes in detail the unfolding of language maintenance dynamics. The thesis presents valuable insight into the underlying beliefs about Amharic and Spanish, the role of explicit language management strategies, parental socialisation and discourse styles and children’s agency. As the first such research covering two recent refugee communities it will hopefully assist the individual families to socialise their children in a way that enables them to become proficient minority language speakers. This will ensure a linguistically rich future for New Zealand.

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  • Being musical : teachers, music and identity in early childhood education in Aotearoa/New Zealand

    Bodkin, Sally (2004)

    Doctoral thesis
    University of Otago

    ix, 294 leaves ; 30 cm. Includes bibliographical references. University of Otago department: Music.

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  • The Southland variety of New Zealand English : postvocalic /r/ and the bath vowel

    Bartlett, Christopher Mark (2002)

    Doctoral thesis
    University of Otago

    xiii, 177 leaves :ill. ; 30 cm. Includes bibliographical references. University of Otago department: Anthropology. "13 December 2002" -- T.p.

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  • Designing oligoarginine-associated PECA nanoparticles for enhanced cellular uptake

    Chiu, Jasper Ze Siong (2015)

    Doctoral thesis
    University of Otago

    Introduction: Polymeric nanoparticles can be used as carriers to improve oral bioavailability of therapeutic peptides or proteins. These polymeric carriers can be formulated with cell-penetrating peptides such as oligoarginine to further enhance uptake. Such a combined formulation could deliver bioactive effectively, using less oligoarginine than required for effective cell permeation using oligoarginine alone. The aims of this study were to formulate poly(ethylcyanoacrylate) (PECA) nanoparticles with oligoarginine, characterize the resulting nanoparticles and investigate their in vitro uptake. Methods: PECA nanoparticles were produced by in situ polymerization in a water-in-oil microemulsion. Various oligoarginines were dissolved in the aqueous phase of the microemulsion prior to the addition and polymerization of monomers, to produce different oligoarginine-associated nanoparticles. The resultant nanoparticles were characterized for size and zeta potential in ultra-pure water and the cell incubating medium (Hanks Balanced Salt Solution, HBSS). The nature of the association between oligoarginines and nanoparticles was investigated by MALDI-TOF mass spectrometry. The uptake of the oligoarginine-associated nanoparticles, loaded with a fluorescent probe, by Caco-2 cells was investigated using fluorescence-activated cell sorting (FACS) and confocal imaging. Uptake studies were conducted in both undifferentiated cells and fully differentiated cell monolayers. The uptake of radiolabeled oligoarginine nanoparticles by Caco-2 cells was quantified by scintillation counting and the accumulation of nanoparticles on the cell surface was evaluated with a mathematical simulation model. Results: PECA nanoparticles formulated with di-arginine-histidine (RRH) and tetra-arginine-histidine with an aminocaproic acid spacer (R4acaH) were cationic (zeta potential of +35 and +33.5 mV, respectively) and approximately 200 nm in diameter. Mass spectrometric studies revealed that RRH was covalently tagged to the PECA nanoparticles via histidine but R4acaH was not. Because these RRH-tagged nanoparticles aggregated in HBSS, poloxamer-407 surfactant was added to stabilize the colloidal system. However, the addition of surfactant was found to neutralize the positive zeta potential of the nanoparticles. RRH-tagged nanoparticles associated with a higher proportion of undifferentiated Caco-2 cells after 2 h incubation than unmodified nanoparticles and confocal imaging showed that they were mainly located on the cell surface. Association of RRH-tagged nanoparticles in fully differentiated Caco-2 cell monolayers was not increased compared to that of unmodified nanoparticles. The accumulation trend of PECA nanoparticles on the cell surface predicted by a mathematical simulation model was consistent with the cellular experimental data. Conclusions: PECA nanoparticles associated covalently with RRH via histidine anchoring to produce cationic nanoparticles, which were neutralized in the presence of surfactant. These nanoparticles adhered to undifferentiated Caco-2 cells to a greater extent than unmodified PECA nanoparticles. However, scintillation counting data revealed that the greater tendency to adhere did not result in greater uptake of the RRH-tagged nanoparticles in fully differentiated Caco-2 cell monolayers, which was consistent with the findings of flow cytometry. Mathematical simulation modelling was able to predict the low accumulation of the nanoparticles at the bio-interface but did not account for the adherence tendency of the nanoparticles and the initial contact adherence that occurred during convection mixing upon introduction of the formulation to the cells. Further surface characterization of the RRH-tagged nanoparticles is required to gain deeper insight into the nature of the interaction at the cellular bio-interface. Although fluorescence analysis (such as FACS and confocal imaging) was able to quantify the proportion of cells associated with the polymeric nanoparticles and verify internalization, scintillation counting data complemented the cellular association with invaluable information on the proportion of nanoparticles associated with the cells. Therefore, these techniques should be used together to critically assess cellular association and uptake.

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  • Investigation of the Factors that Limit the Shelf Life of Fresh Chilled Pasteurized Milk

    Alothman, Mohammad (2015)

    Doctoral thesis
    University of Otago

    The stated shelf life of fresh chilled pasteurized milk (FCPM) in New Zealand is 14 days, which although considered long enough to meet the needs of the domestic market, limits its export potential. The shelf life of FCPM is usually limited by the growth of microorganisms including Gram-positive spore-forming bacteria that survive the pasteurization process and psychrotrophic Gram-negative bacteria (particularly Pseudomonas sp.) that can re-contaminate the milk during bottling. During growth, microorganisms produce different combinations and concentrations of volatile organic compounds (VOCs) in FCPM, some of which are perceived as off-flavours and influence the sensory quality and shelf life of FCPM. The total number of microorganisms in milk is used as a broad indicator of quality by the dairy industry. However, FCPM containing high microbial numbers can be palatable, while FCPM with lower microbial numbers can be rejected by consumer depending on the activity of the contaminating microbes. Therefore, to ensure the production of FCPM with an export potential (i.e., shelf life > 14 days), a better understanding of the effect of microorganisms (types and numbers) on the sensory quality and the shelf life of FCPM is required. The present study was comprised of 5 experiments that covered three broad tasks. The first task focused on studying changes in the microbial population and the VOC composition (using proton transfer reaction – mass spectrometry (PTR-MS)) in three types of FCPM, namely whole fresh chilled pasteurized milk (WFCPM), high protein – calcium fortified milk (HP-Ca), and skim (Trim) milk during extended storage for up to 26 days (Chapter 4). This experiment was followed by two sensory studies which examined the relationship between changes in the microbial quality, the VOC composition, and the sensory quality of FCPM during storage using firstly a consumer based method (Chapter 5) and then a trained descriptive panel (Chapter 6). The experimental work was concluded by two inoculation studies (Chapter 7 and 8), which investigated the spoilage potential of a number of microorganisms, isolated from aged FCPM (3-21 days) and inoculated into FCPM as either pure or mixed cultures of microorganisms. It was found that post pasteurization contamination (PPC) with Gram-negative bacteria is what primarily limits the shelf life of FCPM in New Zealand. In the absence of PPC, the milk maintained a good quality and had a shelf life of beyond 14 days. The initial microbial population in FCPM was mainly comprised of spore-forming bacteria, however, Gram-negative psychrotrophic microorganisms dominated the microbial population as the milk aged. The different species and numbers of microorganisms entering the milk via PPC caused batch-to-batch and within batch variations in the shelf life of FCPM, due to differences in their initial numbers at the time of contamination, growth rates, and spoilage potential. Owing to this variation in the species and numbers of microorganisms in the milk, it was determined that storage time correlated poorly with VOC and the end of shelf life. Rather, microbial numbers correlated well with increases in VOC concentrations and the end of shelf life which was determined at an estimated rejection threshold (RjT) by consumers occurring when microbial numbers exceeded > 107 CFU.mL-1. The RjT (end of shelf life) was defined as when a unanimous decrease in consumers’ preference occurred due to changes in the sensory characteristics of FCPM. At the same RjT, significant changes in the signal intensities for a number of spoilage-related volatile mass ions occurred in the headspace of FCPM (p≤0.05), including m/z 33, 45, 47, 61, 63, 71 and 89, which were tentatively identified as being methanol, acetaldehyde, ethanol, acetic acid, dimethyl sulfide, butanoic acid or 2-pentanol respectively. Extended storage of WFCPM (26 days) resulted in significant changes in a number of the key sensory characteristics of the milk determined by descriptive sensory analysis namely cheesy odour, cultured odour, barny odour, cheesy flavour, cultured flavour, creamy flavour, sweet taste, mouth coating, sweet after swallow, and creamy after swallow (p≤0.05). These changes had a weak relationship with the microbial quality due to the low number of microorganisms detected in WFCPM throughout the storage period. However, a better relationship between changes in the sensory characteristics and the VOC composition of WFCPM was found suggesting that the contaminating microorganisms had strong spoilage potential despite their occurrence at low numbers. Inoculating FCPM with microorganisms isolated from aged FCPM showed that microorganisms varied in their ability to grow in FCMP at 4.5 °C ± 0.5 and to cause changes in its VOC composition (i.e., had differing spoilage potential). In addition, inoculating milk with different combinations of mixed bacterial cultures of two strains of Pseudomonas fluorescens and Chryseobacterium sp. resulted in VOC composition that is similar but not equal to that inoculated with pure cultures of the dominating bacteria. This could be ascribed to the interaction (competition and/or synergism) that occurs between bacteria during growth. In conclusion, in the absence of post pasteurization contamination FCPM had a shelf life (time before RjT), which exceeded 14 days. However, depending on the spoilage potential of the contaminating microorganisms, PPC could result in changes in the VOC composition and the sensory quality of the FCPM that result in its rejection by consumers if microbial numbers exceeded approximately 107 CFU.mL-1 regardless of the storage time. Preliminary trials carried out in the bottling plant identified a number of potential sources of PPC and it is suggested that eliminating these potential sources will enable the production of milk, which consistently has a shelf life exceeding 14 days.

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  • The Moriori. The integration of Arboriculture and Agroforestry in an East Polynesian Society

    Maxwell, Justin James (2015)

    Doctoral thesis
    University of Otago

    The Chatham Islands were a challenging environment for East Polynesian colonisers. The successful long term settlement of these islands can be attributed to the first people applying and adapting Polynesian strategies to the colonisation of an unfamiliar environment. Previous studies have suggested that settlement and subsistence practices were entirely focused upon the collection of wild plants and fauna, throughout the Moriori sequence with a heavy dietary reliance on one marine species, the New Zealand fur seal (Arctocephalus forsteri). This interpretation is not consistent with the results of this research. In this thesis a holistic multi-proxy research design is used to identify terrestrial plant use by Moriori and the landscape modification which is associated with the introduction of East Polynesian subsistence practices. The primary data sets employed are the ethnographic and historical accounts of Moriori subsistence, archaeological investigations of the broad-leaved forests and associated sites, anthracological and palynological analyses to identify past vegetation regimes and the anthropogenic effects, and to date when humans began to modify the environment. The results suggest that after an initial period of rapid population growth, even though marine mammals were still available in large numbers, the first settlers began to modify the environment to increase terrestrial production. It is argued that the environmental changes occurred in part to increase the productivity of wild plants, particularly bracken fern (Pteridium esculentum). The most important change to the vegetation was the intentional introduction and management of the mainland New Zealand endemic tree Corynocarpus laevigatus. The broad-leaved forests, a previously under-researched component of Moriori subsistence, are shown to have been actively managed by Moriori. They were an integral component of the subsistence practices in the ‘late’, post-1650AD, Moriori sequence. The introduction and cultivation of Corynocarpus laevigatus was essential to the long term colonisation of the Chatham Islands in the absence of the standard tropical East Polynesian cultigens.

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  • Life history and distribution of mysid species in a large open estuary

    Bierschenk, Beate Monika (2015)

    Doctoral thesis
    University of Otago

    In the highly dynamic environment of an estuary, environmental factors such as salinity, temperature, light and hydrodynamics as well as biogenic factors such as predator/prey interactions influence the population dynamics of estuarine species. The aim of my study was to explore the potential for resource partitioning between four commonly co-existing estuarine mysid species, Tenagomysis chiltoni, Tenagomysis novae-zealandiae, Tenagomysis macropsis, and Gastrosaccus australis, by investigating their life histories, seasonalities and distributions within an estuary. Mysid samples were collected along the shoreline (water depth: 0.5 – 0.6 m) of the Taieri Estuary (South Island, New Zealand) using a sweep net and in the deeper water (water depth: 4 – 6 m) with a set of 3 drift nets. A lateral segregation in the estuary was found between the two hyperbenthic species, T. chiltoni and T. novae-zealandiae, and the two benthopelagic species, G. australis and T. macropsis with hyperbenthic mysids mainly occurring in the shallow waters along the estuary shoreline and benthopelagic species in deeper central-channel waters. The life cycle and breeding dynamics of all four mysid species were similar to those described in the literature for other temperate estuarine mysid species, although the breeding period in the study estuary was noticeably shorter than in estuaries of lower latitudes in New Zealand and elsewhere. The observed seasonal migrations and life-stage specific segregation between adults and juveniles may reduce competition, inter-specific predation, and cannibalism by allowing different life stages to utilise the same habitats or food sources, but at different times. Water temperature seems to play a key role for the timing of the breeding season, abundance, and reproductive effort, whereas salinity, total suspended solids and phytoplankton biomass (measured as chlorophyll a) were associated with the distribution of the mysid species. Thus, the spatial distribution of these four mysid species within the Taieri Estuary reflects the complex linkages and interactions between favourable temperature and salinity conditions, food availability and reproduction. As a consequence of confirming the lateral and longitudinal segregation of species and life history stages within the estuary, the question arose of how relatively small aquatic organisms, such as mysids, orient themselves in a large three-dimensional body of moving water. Therefore the role of turbulence as an orientation aid was investigated in a flume tank experiment, using Gastrosaccus australis as the test organism. The mysids actively tracked areas of shear, when turbulence was present, but favoured reduced flow in the absence of turbulence. These different swimming responses might be an adaptation of G. australis to its pelagic habitat. By moving to reduced flow areas in an absence of mid-water turbulence, mysids could avoid seaward displacement. Change in riverine management such as by water abstraction, damming for hydropower plants, or extreme weather events associated with climate change will impact distribution, densities and population dynamics of the resident mysid species in estuaries. These changes in abundance or, in the worst case scenario, even the loss of mysid species could potentially have severe consequences for estuarine food webs, which may result in decreased food availability and therefore impact the nursery function of estuaries for commercial fish species.

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  • Screening for Antisocial Development

    Tyler-Merrick, Gaye Margaret (2014)

    Doctoral thesis
    University of Canterbury Library

    Teachers report that there are an increased number of students engaging in persistent antisocial behaviour in their classrooms. Teachers need to identify these students early because if there is early identification then there is the potential for early intervention, which in turn may prevent negative long-term outcomes for these students as well as long-term costs to society. The aims of this study were (1) develop a psychometrically sound, cost effective, three-step multiple gating behaviour screening procedure that teachers could use in their kindergarten/classroom so that they could identify those students at-risk of antisocial development, (2) examine if the third gate of this procedure was necessary for the accurate identification of these students, and (3) could such a screening procedure be adapted for classroom teacher use in New Zealand kindergartens and schools. Forty eight teachers from three kindergartens and 10 primary/intermediate schools volunteered for the study, of which 34 teachers completed all three gates of the screening procedure. Results indicate the three gate screening procedure was easily adapted for kindergarten and classroom use with, at Gate 3, teachers’ self-recording 30 direct observations of a nominated and control student during their normal teaching lesson with good accuracy. All three gates were effective in identifying those students at-risk of antisocial development but Gates 1 and 2 were the most effective in terms of accuracy, time and resourcing. The teachers found the three gate procedure manageable, required very little training and did not interrupt classroom routine or schedules. The implications of these findings are discussed.

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