11,859 results for Doctoral

  • Augmented Community Telerehabilitation Intervention to Improve Outcomes for People With Stroke. ACTIV: A Randomised Controlled Trial and Qualitative Enquiry

    Saywell, Nicola Lesley

    Doctoral thesis
    Auckland University of Technology

    For people to achieve and maintain the best possible outcomes after stroke, a level of rehabilitation input is required that cannot be met by current services. Telerehabilitation, the provision of rehabilitation at a distance using telecommunication technology, has been proposed as a way to extend the reach of rehabilitation, particularly to those for whom geography, poverty or disability preclude easy access to rehabilitation facilities. The difficulty with many potential modes of delivering telerehabilitation, is that they are expensive and complex, requiring significant technical input for satisfactory use. The use of readily-accessible telecommunication technology (landline telephones or mobile phones) to deliver stroke rehabilitation remotely was mooted as a possible solution, based on findings of feasibility and acceptability of use, in a number of small-scale studies in other populations. The idea was investigated using a systematic review, which showed that while mobile phones were almost ubiquitous in New Zealand, there had been minimal investigation of their use in stroke rehabilitation. A novel intervention was developed, based on the literature review and the clinical experience of the research team. Augmented Community Telerehabilitation Intervention (ACTIV) is a structured 6-month programme, delivered by physiotherapists using a combination of face-to-face sessions, telephone contact and text message reminders to support rehabilitation for people following stroke after standard rehabilitation has ended. A randomised controlled trial was undertaken, to compare the effectiveness of ACTIV with a usual care control, to improve outcomes for people with stroke. Measures of physical function and self-efficacy were taken immediately after ACTIV and 6-months after the end of the programme. A qualitative enquiry was also undertaken with a sample of those who had completed ACTIV, to explore the participant experience. The results of the trial showed that ACTIV improved physical function in people undertaking ACTIV as long as they undertook at least 50% of the programme. However, the significant improvement in physical function immediately after the programme was not sustained 6-months after cessation. A significant improvement was found in participation immediately after ACTIV, which also was not sustained at 6-months post-intervention. The qualitative enquiry showed that despite the first impression of ACTIV not being proper physiotherapy, there was a strong message that participants felt they had not been left to struggle alone and gained a number of benefits from the therapeutic relationship they developed with the physiotherapist during ACTIV. Participants also communicated strong feelings of making progress and a very clear impression of knowing what they wanted from rehabilitation. This was not the participant-generated goals, decided with the physiotherapists at the start of the programme, but a desire to keep on making small forward steps towards normality. Findings from the ACTIV study showed that a small input can make a significant difference for people after stroke but that the longed for behaviour-change leading to absolute independence from any support may be an unrealistic expectation. ACTIV may need to be extended in partnership with non-governmental agencies to continue a level of support that ensures benefits are maintained.

    View record details
  • New Zealand year 10 students' out-of-school reading and its recognition, support and use for engagement within English classrooms.

    Ladbrook, Judine (2016)

    Doctoral thesis
    The University of Auckland Library

    Four issues in reading in New Zealand (NZ) secondary schools are inequitable achievement, a decline in adolescent book reading for pleasure, a lag in boys??? performance and, in international comparisons, NZ 15 year-olds are less confident using digital text. Out-of-school book reading is strongly related to academic achievement with motivation crucial. But, reading motivation declines in adolescence. Research suggests adolescents can exhibit literacy capabilities with digital text beyond their traditional text capabilities. This, plus the demand for ???new literacies,??? has led to calls to reconceptualise school literacy. Studies demonstrated NZ 15 year-olds lacking information processing skills, but integrating digital technologies into pedagogy had barriers. NZ research gaps include exploring adolescents??? reading motivations, out-of-school reading including digital text, and group differences. Whether English teachers embrace broad text definitions, which texts they value, and whether they know what students read to give them profitable visibilities, are under-researched areas. Using a broad text definition, this thesis asked, ???What do NZ Year 10 students read out-of-school and is this reading recognised, supported and used for engaging students in learning within English classrooms???? Sub-questions explored gender and socio-economic differences and students??? reading motivation. Questions concerning teacher knowledge of students??? out-of-school reading, the value placed on different texts and which were visible in programmes, guided the English programmes??? investigation. Data were collected in three large central-urban co-educational schools representing different socio-economic communities, from 190 Year 10 students and 24 English teachers. Students completed a survey including a motivation questionnaire. In each school, frequent readers and high digital-text-users completed a 14-day diary activity and a focus group conversation. Teachers completed a survey and three were interviewed. Results showed 81% of students reading books ???recently??? but 41% reading infrequently, with socio-economic and gender differences. Curiosity and recognition motivated reading, showing a teacher role. Social-networking and researching were central digital activities but students required information literacy assistance. Extensive-reading programmes needed improvements and teachers chose time-honoured texts with digital text featuring minimally. Implications include time investments to connect with and motivate students??? out-of-school page and digital reading, professional learning around motivational knowledge and digital texts, and text access within schools.

    View record details
  • Methodologies for assessing domestic hens' preferences for sounds

    Jones, Amy Rebecca (2011)

    Doctoral thesis
    University of Waikato

    A series of five experiments assessed the effects of different sounds on the choice behaviour of domestic hens and chicks using a range of procedures. The first experiment compared the effects of white noise on hens’ performance under multiple-concurrent schedules with those of other sounds (an alarm call, the sounds of hens feeding and a food call) with the same subjects. The sound was shown to bias responding of hens away from the keys associated with all sounds and the magnitude of this bias was largest for white noise and the food call. Different to the other sounds, white noise suppressed the responding of hens when it was present, thus confounding response allocation. In Experiment 2, a concurrent-chains procedure was used to assess hens’ preferences for the same sounds used in Experiment 1. Sound was associated with one terminal-link and hens made a choice between sound and no sound alternatives in the absence of sound. The direction of noise biases from responding in the initial-links was the same across hens for one sound only (food call) but the magnitude of these biases varied. This was different from Experiment 1 but terminal-link responding was suppressed in the presence of sound, as in Experiment 1. Terminal-link entry pauses also tended to be longer in terminal-links that contained most sounds but the effect was greater with white noise and the food call. A conditioned place preference procedure was used in Experiment 3 to assess chicks’ preferences for places associated with sounds, in the absence of reinforcement or sound. Baseline preferences were assessed by measuring time spent in each compartment of a 3-compartment chamber. Groups of chicks were then conditioned to either food or a sound by being confined in one compartment. The chicks’ post-conditioning test sessions showed a significant conditioned place preference towards the area associated with food and away from the area associated with white noise. This experiment showed that the conditioned place preference procedure could be used to assess the conditioning effects of sound and food on domestic hen chicks and confirms the results found with white noise. As all previous experiments identified sounds that were only not preferred, Experiment 4 attempted to make a preferred sound for hens by associating a pure tone with food. Preference for this tone was assessed in the same manner as Experiment 1. The direction of preferences across subjects was inconsistent, thus this experiment was not successful. One possible reason for the inconsistent results could have been the use of a pure tone. Experiments 1 and 2 showed that white noise and the food call affected responding of hens and so it was thought possible that associating these sounds with food would increase preferences towards them. Thus, Experiment 5 used the same procedure as Experiment 4 to associate food with white noise and a food call. Two training phases, one with food and one without food, increased noise biases away from the keys associated with sound during the preference assessment. It was theorised that the training phase made sound unpredictable and the hens no longer had control over its presence or absence, therefore making the sound less preferred and more aversive. Overall, the results of this thesis suggest that white noise is an aversive stimulus for domestic fowl and that concurrent schedules and the conditioned place preference procedure could be used with other species to assess their preferences for environmental stimuli, which would provide information that may aid in improving their welfare.

    View record details
  • The Chemokine-binding Proteins Encoded by Bovine Papular Stomatitis Virus and Parapoxvirus of Red Deer in New Zealand: Molecular and Functional Characterization

    Sharif, Saeed (2017)

    Doctoral thesis
    University of Otago

    Poxviruses are large DNA viruses that infect a wide range of animals including humans. During the course of evolution, these complex viruses have gained an extensive repertoire of immunomodulatory genes to evade host immune responses in order to enhance their own survival. One of these immunomodulators is a secreted soluble chemokine-binding protein (CBP) which has no known mammalian homologue. Chemokines are a large family of chemotactic proteins that regulate recruitment of leukocytes to sites of infection or inflammation, as well as homeostatic migration of leukocytes through lymphoid organs. Members of the chemokine family are classified as CXC, CC, C and CX3C based on the arrangement of cysteine residues at the N terminus. The majority of the known chemokines fall into either the CXC or the CC classes. In general, CXC chemokines are potent chemoattractants of neutrophils or lymphocytes, whereas CC chemokines are chemoattractants for monocytes. The CBP genes have been identified in Orthopoxviruses and Leporipoxviruses, as well as Parapoxviruses (PPVs) that includes Orf virus (ORFV), and genes encoding putative CBPs have been identified in Pseudocowpox virus (PCPV), Bovine papular stomatitis virus (BPSV) and Parapoxvirus of red deer in New Zealand (PVNZ). Previous studies have demonstrated the structural and functional activity of ORFV-CBP, however, there is little known about the CBPs of the other PPVs. This study describes the characterization of CBPs secreted by two less-studied members of the PPVs; BPSV and PVNZ. BPSV and PVNZ infect cattle and red deer, respectively, and induce superficial pustular skin lesions and lesions of the oral mucosa. Further PVNZ infects the velvet of antlers. In the case of BPSV infections, the immunity is short lived, a phenomenon that could be related to the immunomodulators encodes by the virus. In chapter two, the molecular properties of BPSV and PVNZ CBPs are described. Mass spectrometry revealed that the BPSV-CBP is a homodimeric polypeptide with a MW of 82.4 kDa, and sequence analysis showed around 40% identity and 70% similarity between the CBPs of BPSV and ORFV at the amino acid level. Moreover, structural modelling based on the crystal structure of the orf virus CBP, predicted a similar beta-sheet sandwich for both proteins, suggesting that like ORFV-CBP, BPSV-CBP may have broad-spectrum chemokine binding properties. PVNZ, unlike other PPVs, express three distinct CBPs (namely 112.0, 112.3 and 112.6). The CBPs of PVNZ112.0 and PVNZ112.3 have 46% identity and cluster together, while PVNZ112.6-CBP has only about 30% identify with the other PPV-CBPs and falls into a separate branch of phylogenetic tree. It seems that multiple PVNZ-CBPs have arisen by a process of duplication and divergence from a common ancestral gene. Although sequence analysis of the PVNZ-CBPs showed a moderate degree of identity (30-40%) with the ORFV-CBP, it predicted a conserved structural core for PVNZ-CBPs, suggesting a certain chemokine-binding activity for these viral proteins. Chapter three describes a comprehensive chemokine-binding screen of BPSV-CBP and the PVNZ-CBPs by surface plasmon resonance (SPR) assay. The SPR results showed high-affinity binding of the BPSV-CBP to a wide-range of inflammatory murine chemokines within the CXC, CC and XC classes. Murine cells and mice were used in subsequent studies to characterise the in vitro and in vivo functions of BPSV-CBP. The SPR assay also revealed that each PVNZ-CBP has a unique chemokine-binding profile. In general, PVNZ-CBP 112.3 binds to CXC chemokines selectively, while PVNZ-CBP 112.6 has strong binding affinity with CC chemokines. Remarkably, PVNZ-CBP 112.0 had no or weak binding against most of the chemokines tested. The spectrum of the inflammatory chemokines targeted by the CBPs of BPSV and PVNZ suggest that like orf virus, these Parapoxviruses target inflammation as a strategy to subvert immune cell activation and recruitment to infected tissue. In chapter four, murine neutrophils and monocytes were used in transwell migration assays to investigate the in vitro effects of BPSV-CBP on chemokine-induced chemotaxis. Mature neutrophils were differentiated from a mouse promyelocytic (MPRO) cell line and shown as Ly-6Ghi CD11bhi cells that express the chemokine receptor CXCR2. After optimizing the neutrophil migration in response to CXCL1, CXCL2, and CCL3 chemokines, the BPSV-CBP was shown to cause a significant reduction in cell migration at a molar ratio of chemokine-to-CBP of 1:4, 1:1 and 1:1 respectively. Moreover using monocytes derived from mouse bone marrow cells cultured in the presence of M-CSF, and characterized as CD115+ CD11b+ Gr-1+ cells, BPSV-CBP potently inhibited their migration towards skin-related inflammatory chemokines CC2, CCL3, and CCL5 at the molar ratio of chemokine-to-CBP of 1:1, 1:1, and 1:0.5, respectively. Finally, a lipopolysaccharide (LPS)-induced murine inflammatory skin model was applied to evaluate the in vivo impact of the BPSV-CBP. Histological examination, in conjunction with a myeloperoxidase (MPO) assay of skin samples, revealed that intradermal injection of the BPSV-CBP reduced the influx of neutrophils (Gr-1+ MHC-II+) into the inflamed sites at 12 h post LPS injection. Moreover, the BPSV-CBP reduced infiltration of MHC-II+ monocyte/dendritic cells into inflamed skin. Overall, this study showed that the BPSV-CBP is an antagonist for a wide range of chemokines, and can inhibit the migration of inflammatory immune cells both in vitro and in vivo. These findings suggest that the CBP could be important in virulence and pathogenesis of BPSV infections. Importantly, the broad binding properties of the CBPs suggest that they may have therapeutic value as anti-inflammatory drugs.

    View record details
  • An analysis of National Certificate of Educational Achievement chemistry courses in terms of curriculum, pedagogy and assessment: With comparison to the International Baccalaureate Diploma

    Tewkesbury, Michelle (2017)

    Doctoral thesis
    Victoria University of Wellington

    New Zealand has seen significant change in curriculum and qualification frameworks in recent years. The implementation of the National Certificate of Educational Achievement (NCEA) from 2002 and a revised national curriculum in 2007 have underpinned the forces of change. However, preceding its implementation, the NCEA qualification sparked controversy both in the education literature and general media. This controversy around the NCEA continues. Classroom-based evidence on the impact of the NCEA on teaching and learning has a significant role in informing policy, and this work aimed to make such a contribution. As a number of secondary schools in this country offer alternative senior school qualifications, this invited the opportunity to compare the phenomenon of teaching chemistry to Years 12 and 13 students under two structurally different qualification frameworks. The overarching research question investigated in this study was: In the context of NCEA and International Baccalaureate Diploma (IBD) chemistry courses in New Zealand secondary schools, how do teachers manage the tension between learning, teaching, and assessment? Teachers’ views and practices were explored through inquiry questions relating to the following: Teaching the content and procedural knowledge of chemistry (referring to curriculum and pedagogy); and their approaches to assessment. Qualitative research was undertaken from a comparative case study within an interpretive paradigm. Two case schools offered both NCEA and IB Diploma qualifications, and one case school NCEA only. A total of ten participants from the three case schools were interviewed, and short sequences of lessons taught by the participant teachers were also observed. Following the coding of the interview data, emergent themes provided direction for the simple statistical analysis of national NCEA results data. Manageability of courses and their assessment, feeling accountable for high grade outcomes, and the wish for subject specific professional development were areas that teachers of both NCEA and IBDP noted as factors that concerned them. The influence of high-stakes assessment was seen in the teaching methods used in the case schools towards preparing students to attain these qualifications. It was evident from the interviews that participants had much more to say about their teaching of NCEA than they did for the IB Diploma qualification. The imbalance in the collected data, with more being related to the NCEA, was interpreted as arising from issues related to the achievement standard structure of this qualification. The impact of the NCEA on teaching and assessment of chemistry in Years 12 and 13 was found to be significant. NCEA achievement standards were seen to be the default curriculum (rather than the New Zealand Curriculum), and drove course designs in the three case schools. Extrinsic motivation from NCEA credits and grades were considered by the teachers to be key factors in students’ approaches to learning. Courses were designed to maximise grades, and teachers identified the time spent on rehearsal leading up to internal assessment as a concern. When mapped to the New Zealand Curriculum, it was evident that curricular holes in NCEA courses existed; in particular with regard to nature of science and investigation learning objectives. In the case schools, coherence of chemistry as a discipline was compromised in NCEA courses, with implications for students understanding. The performance of schools is evidently being judged, by both government and the media through the publication of league tables of NCEA grade data. This seems to be driving chemistry learning in directions that are counter to international directions in curriculum reform. Based on the findings of this study, several recommendations are made. Attention should be paid to supporting (and resourcing) full implementation of the New Zealand Curriculum, with a focus on subject specific professional development for teachers. The relationship between the New Zealand Curriculum and the NCEA needs addressing; the achievement structure of the NCEA as it currently exists, is coming at a high cost in terms of compromising pedagogy and subject connectedness. Issues of the reliability and validity of NCEA assessment also exist, suggesting that review of current implementation and assessment policy, including that relating to the conduct of national examinations, need review.

    View record details
  • Dimensions of ???Quality??? In The Case Of Foreign Degree Awarding Institutes of Sri Lanka: A Multiple Stakeholder Perspective

    Amugoda K Dona Wickramasinghe, MN (2015)

    Doctoral thesis
    The University of Auckland Library

    The provision of quality higher education is of critical importance for the economy of a developing country like Sri Lanka. This research considering the quality issues of the foreign degree awarding institutes of Sri Lanka investigates the dimensions of quality in relation to these institutes from a multiple stakeholder perspective. The central argument of this thesis is that it is necessary to understand what constitutes as quality in order to improve it. Thus, the study is aimed to identify various understandings of quality in relation to these institutes and their consequences to various stakeholders of these institutes. The study identifies key definitions, purposes and practices associated with the term quality. The students??? and the professionals??? perceptions of how these institutes implement and maintain the key quality criteria and the key issues arriving from the various understandings of quality are also investigated from the receiver country???s perspective. The study adopted a mix of vertical case study and mixed methods approach and worked within a pragmatic paradigm. A questionnaire survey, semi structured interviews and documentary data served as sources of data. The perceptions of students, lecturers and senior managers of five selected foreign degree awarding institutes of Sri Lanka and the officials of three government higher education organizations were sought to achieve the research objectives. The findings revealed a variety of definitions of quality and also various meanings to these definitions, indicating the elusive nature of quality. It was revealed that quality is shaped by external factors such as economy, culture, gender and social class. The different viewpoints of these stakeholders also created confusion, discrepancies and many challenges to quality in these institutes. The findings revealed that the quality of these institutes analysed are neither up to the standards of the government universities of Sri Lanka nor to the standards of their home universities. The way that some of these institutes studied, implemented and maintained quality did not resemble their claimed definitions, purposes and practices of quality, and these mismatches brought out several consequences to the stakeholder groups, while also making a negative impact on the higher education sector of Sri Lanka. The study provided recommendations to the key stakeholder groups to overcome these identified issues of quality.

    View record details
  • Childhood food allergy in the New Zealand context: An exploration of trends, prevalence, risk factors, and the impact on quality of life

    McMilin, Colleen (2015)

    Doctoral thesis
    The University of Auckland Library

    Although food allergy has been extensively described, diagnosed, managed and researched, many questions still linger. For over 2000 years scientists have sought to understand the effects of food on the human body. Hippocrates, the Father of Medicine, had recognition that food can cause illnesses, disease and health concerns for some people. In 1906, Dr Clemens von Pirquet suggested the use of the word ???allergy??? to describe an inappropriate reaction to food or other substances not typically harmful or bothersome. Researchers are just beginning to recognise potential influences on the development and progression of food allergy. The prevalence and incidence rates of food allergies worldwide have been the subject of much debate in recent decades due to what many observe as a dramatic increase in childhood food allergies. A food allergy touches the life of not only the individual diagnosed but also their family, friends, health care providers, food producers, retailers, and schools. The epidemiology of food allergy in New Zealand has been incompletely described and there is minimal published data that allows for any estimation of the disease burden caused by food allergy in New Zealand. Aims Although New Zealand has a high prevalence of asthma, the epidemiology of other atopic disease has not been studied. Based on other studies completed around the world and the data available in New Zealand this thesis set out to better understand: (1) temporal trends in food allergy; (2) prevalence of peanut allergy and risk factors for peanut allergy; and (3) the impact of childhood food allergy on quality of life. Methods To meet the objectives of this thesis four projects made up of five studies were completed. Each project utilised a different data set to allow comparisons to be made of data from New Zealand with that which has been reported from other countries and to provide several perspectives on how food allergies are impacting New Zealand children. 1) To determine whether Emergency Department presentations can be used to describe temporal trends in food allergy presentations an audit was completed for all emergency department (ED) presentations from 1988 to 2011 of children (0 to 14 years old) to the public hospital ED in the Auckland District Health Board (ADHB) region, for which the ICD codes ???anaphylaxis, unspecified??? or ???allergy, unspecified???, were assigned. 2) The new knowledge learnt from project one was then applied to the National Minimum Dataset (NMDS), a national collection of public and private hospital discharge information, temporal trends in emergency department (ED) presentations for food-related acute allergic reactions from 1988 to 2011 of children (0 to 14 years old) were investigated. 3) Utilising data from the Growing Up in New Zealand cohort study the prevalence of peanut allergy and factors associated with the presence of peanut allergy at age two years were investigated. 4) The impact of food allergy on quality of life was investigated through the use of reflexive photography, photo elicitation, and the autodriven interview with food allergic children and their families. Results Understanding Administrative Coding of Emergency Department Visits for Unspecified Acute Allergic Reactions The aim of this project was to determine the proportion of ED visits coded as ???anaphylaxis, unspecified??? or ???allergy, unspecified??? that are food-related allergic reactions. Food-related acute allergic reactions account for 29% of hospital presentations that were assigned a discharge code for ???anaphylaxis, unspecified??? or ???allergy, unspecified in the ADHB. The ED presentation rate with food-related allergic reactions from 2004-2011 was almost twice as high as that which occurred from 1988-1995 (RR=1.98, 95%CI 1.10-3.72). By contrast, ED presentation rates for non-food-related allergic reactions did not change over these years. This apparent increase in New Zealand is consistent with observations using comparable data sources reported from Australia and the United States. Hospital Presentations Due to Acute Allergic Reactions Related to Food Between 1988 and 2011, 3,735 children 0 to 14 years old presented to a New Zealand hospital with an acute allergic reaction identified by ICD-9-CMA-II codes 692.5 (contact dermatitis and other eczema due to food in contact with), 693.1 (Dermatitis due to food taken internally), 995.0 (Anaphylactic reaction due to unspecified food), 995.3 (Allergy, unspecified), and 995.60-995.69 (Anaphylactic reaction due to food unspecified and specified). An average yearly increase of 8% in hospital presentations due to acute allergic reactions (p=<0.001). Peanut Allergy in the New Zealand Context Based on parental reported data collected from Growing Up in New Zealand, a contemporary longitudinal birth cohort study, 162 (2.1%) children were identified as peanut allergic. Within this cohort, factors associated with the development of a peanut allergy were categorized based on the measurement of child, family & wider influences on disease in early childhood as defined by: child characteristics, proximal social environments, distal social environments, and macro environmental factors. The odds of having parental reported peanut allergy at age two years were increased for boys, children diagnosed with eczema since 9 months, children whose mother had a history of atopic disease (eczema, hay fever, or food allergy), and mothers who identified as being of Asian ethnicity. The odds of having parental reported peanut allergy at age two years were decreased for children who had never tried nuts or peanuts, or whose mothers had no secondary qualifications or secondary school/NCEA 1-4. Impact of Food Allergy on New Zealand Families The impact a food allergy has on a family is influenced by environment and includes four levels home, school, community, and beyond the community. This is due, in part, to the amount of control a food allergic family has within these environments. The ability to control the environment gradually decreases as a food allergic family moves away from the home. Based on the impact a food allergy has on the food allergic family, three outcomes of living with a food allergy are evident responsibility, exclusion, and resilience. The lessons learned from these families can be used to guide other food allergic families through education and advocacy. Based on the family???s description of the impact of a food allergy on their quality of life and management strategies, there is a need for consistent national school policy focused on food allergies and the provision of education and training to hospitality workers. These changes could positively impact food allergic families at multiple environmental levels. Discussion Consistent with what has been reported from several other countries the prevalence of childhood food allergy appears to have increased in recent decades. The rate of parental self-report of peanut allergy in New Zealand is similar to other countries. In New Zealand, children of male gender or who have eczema are at increased, and those who have never tried nuts or peanuts by age two years were at decreased risk of parental reported peanut allergy. In New Zealand children of atopic mothers or mothers of Asian ethnicity are at increased risk and children of less educated mothers are at decreased risk of parental reported peanut allergy. A food allergy impacts all members of a food allergic family based on the level of control within various environments. Food allergy is a complex condition and this thesis provides insight into the current state of food allergy in New Zealand.

    View record details
  • Complementarity modelling of investment in electricity generation capacity

    Jackson, P. R. (2015)

    Doctoral thesis
    University of Canterbury Library

    Complementarity formulations offer the opportunity to thoroughly investigate and clarify the problem of investment in electricity generation capacity. While complementarity has been traditionally used in the sphere of imperfect competition, we demonstrate it also can play a fundamental role in perfectly competitive situations. We demonstrate that our approach offers richer understanding than the traditional linear programming approach. We attempt no judgement as to the practical benefit of our approach, as the benefits themselves depend on the data of the specific counter-factual used. The disadvantages of our approach are somewhat clearer. We acknowledge that the formulations that result are computationally challenging and that the various standard solution methods available for complementarity problems may not actually represent efficient solution methods for such problems. Nevertheless, we adopt the complementarity framework, as ours is a purely theoretical thesis, designed to explore the potential of a unique solution approach to an oft-solved problem. Complementarity theory provides an environment for developing theoretical formulations that, in many cases, resolve directly from an optimisation problem, but it is also free to include other conditions where required. After a brief introduction and literature review, Chapter 1 considers the finer detail of traditional solution approaches, including the use of screening curves, linear programming, and a related complementarity problem. Screening curves were traditionally used in the times of central planning to describe the optimal trade-off between technologies in terms of utilisation, and with the addition of a Load Duration Curve, the optimal capacity of each technology. We explore various representations of the LDC and discuss how these interact with investment conditions and how market clearing procedures are viewed in their context. We show, with the use of an example, that LP approaches are incapable of accurately defining key system performance measures such as the Loss of Load Probability, without either “guidance” from the modeller or through the use of a significant number of load classes or slices. Furthermore, we show that supposedly perfectly competitive models produce prices that are either inconsistent with the perfect competition they are predicated on, or inconsistent with the optimal capacity suggested by the model. Our investigation identifies the reason for this deficiency. Optimal trade-offs have a useful theoretical function, but they also emphasise the nature of the technological choice, and ultimately when the trade-off is with a notional shortage technology, they describe the nature of the total capacity choice. But the screening curve approach quickly succumbs to complexity, and is often replaced by optimisation in the form of linear programming, in which a significant number of constraints could be more easily expressed. Nevertheless, the screening curve concept has some conceptual advantages that we can integrate into the analysis, namely the determination of utilisation levels corresponding to optimal technological trade-offs. Knowing that the traditional LP approach does not accurately reflect the relative timing of investment and operation decisions, or produce solutions that are independent of the LDC definition, we consider the integration of screening curve logic. By way of resolving the downsides of the LP approach, we develop a complementarity formulation that combines the LP solution with the logic of screening curves to derive a problem representation that enables an accurate and consistent solution to the simple problem. In doing so, we make clear that screening curves, per se, are not the motivation, but the vehicle for determining an optimal representation of the system. Complicating the investor’s decision processes are several technological issues, the relevance of which might vary from market to market, but should be considered. Chapter 3 describes a nonexhaustive range of typical problem extensions that would challenge screening curve analysis and how our basic approach can be adapted to include these. This is important for several reasons. Firstly, it is important we demonstrate the overall extensibility of the approach. Secondly, each extension involves discussion of both the extension itself, which in many cases is represented can be accommodated by additional constraints or altered objectives in the underlying optimisation problem, but also the way in which these extensions impact on the definition of the optimal system representation. In deriving the optimal system representation, we develop duality based pseudo-screening curves to describe optimal trade-offs in particular situations or scenarios. By way of example, we consider the relatively standard fare of cost structure generalisation, capacity inflexibility, energy limits and storage, and finally the formulation and interpretation of configurable technologies as non-linear notional technologies. In Chapter 4 we refocus on load. We consider demand response in two forms: the short-term demand response that typically requires investment and can be written as a technology, and the wider type of demand response that comes as a result of adjusting consumption patterns and substitutions. By nature, the latter response is based on longer term considerations and, in the spirit of the investment problem, we develop an approach to including this response in a fashion that excludes this form of demand response from behaving as a marginal technology in the electricity market. We then consider reliability using an endogenous augmented LDC formulation. Finally, we present a formulation and investment analysis of intermittent generation based on a chronological load and generation pattern. This case requires the introduction of an additional level of dynamic LDC generation, and the maintenance of a dynamic mapping between the LDC and the chronological load pattern. No discussion of investment is complete without consideration of risk and uncertainty, and it is therefore important to demonstrate how this can be addressed in our formulation, and what the consequences of risk are. We begin by properly defining these terms before expanding the formulation to consider how risk could be implemented. Our over-arching approach is to develop the framework in accordance with the principles of Ralph & Smeers (2011), including contract market, whose clearance defines the market price of risk endogenously. We distinguish between the perspective of portfolio optimisation based on investor preferences and the perspective of risk constraints using an objective function that combines the expected profits of the firm with a CVaR measure. Uncertainty is presented as a distinct concept. Our presentation focuses on various conjectures and the implications they have for the optimal investment condition. Throughout the thesis, we use the structure of complementarity models as this is both convenient and the basis of much prior research into similar questions. However, complementarity solution methods per se are not the focus of this research, and we refer the reader to those texts listed for a detailed explanation of the theoretical properties and solution methods associated with complementarity problems. We felt it important to be able to describe the problem within a single framework rather than an ad hoc collection of algorithms, and aim to show that, even though decomposing the problem and using algorithms may be more effective than standard complementarity solvers, complementarity formulations can be implemented for a wide variety of purposes.

    View record details
  • Nuclear New Zealand: New Zealand's nuclear and radiation history to 1987

    Priestley, Rebecca Katherine (2010)

    Doctoral thesis
    University of Canterbury Library

    New Zealand has a paradoxical relationship with nuclear science. We are as proud of Ernest Rutherford, known as the father of nuclear science, as of our nuclear-free status. Early enthusiasm for radium and X-rays in the first half of the twentieth century and euphoria in the 1950s about the discovery of uranium in a West Coast road cutting was countered by outrage at French nuclear testing in the Pacific and protests against visits from American nuclear-powered warships. New Zealand today has a strong nuclear-free identity – a result of the New Zealand Nuclear Free Zone, Disarmament and Arms Control Act of 1987 that prohibited nuclear weapons and nuclear warships in the country’s land, air and water – that can be traced back to the first protests against nuclear weapons in the 1940s. This thesis is based on the supposition that the “nuclear-free New Zealand” narrative is so strong and such a part of the national identity that it has largely eclipsed another story, the pre-1980s story of “nuclear New Zealand”. New Zealand’s early embracing of and enthusiasm for nuclear science and technology needs to be introduced into our national story. This thesis aims to discover and reveal that history: from the young New Zealand physicists seconded to work on the Manhattan Project; to the plans for a heavy water plant at Wairakei; prospecting for uranium on the West Coast of the South Island; plans for a nuclear power station on the Kaipara Harbour; and the thousands of scientists and medical professionals who have worked with nuclear technology. Put together, they provide a narrative history of nuclear New Zealand. Between the “anti-nuclear” voices, already well told in many histories of nuclear-free New Zealand, and the “pro-nuclear” voices revealed in this thesis, options were considered and decisions made. This thesis shows that the people with decision-making power tended to make practical decisions based on economics and national interest when it came to deciding whether or not to adopt a certain piece of nuclear technology or whether or not to participate in projects or ventures with international agencies. This eventually led to a nuclear-free policy – focused on weapons, nuclear-powered ships and waste – that since the legislation was enacted in 1987 has been interpreted ever more widely by politicians and the public to include nuclear power, uranium prospecting and many other applications of nuclear technology.

    View record details
  • Detection of Large Holocene Earthquakes in the Sedimentary Record of Wellington, New Zealand, Using Diatom Analysis

    Cochran, Ursula Alyson (2002)

    Doctoral thesis
    Victoria University of Wellington

    New Zealand is situated on the boundary between the Pacific and Australian tectonic plates. The Wellington region lies near the southern end of the Hikurangi subduction zone and within a zone of major, active strike-slip faults. Wellington's paleoseismic and historic records indicate that large surface rupture earthquakes have occurred on these faults in the past. Development of a complete record of past large earthquakes is a high priority for the region because of the risk posed by occurrence of large earthquakes in the future. The existing paleoseismic record has been derived predominantly from studies of fault trench stratigraphy, raised beach ridges and offset river terraces. The sedimentary record of lakes and coastal waterbodies is a source of information that has not been used specifically for paleoseismic purposes in the region. Therefore investigation of Wellington's sedimentary record is used in this thesis to make a contribution to the paleoseismic record. Holocene sedimentary sequences are studied from three small, low elevation, coastal waterbodies: Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri. Sequences of between 200 and 650 cm depth were collected using a hand-operated coring device. Sedimentology and diatom microfossil content were analysed and interpreted to enable reconstruction of paleoenvironment at each site. Radiocarbon dating was used to provide chronologies for the sequences that are aged between 5000 and 7500 calibrated years before present (cal. years BP). Diatom analysis is the main tool used to reconstruct paleoenvironment and detect evidence for occurrence of past large earthquakes. To aid reconstruction of sedimentary sequences used in this project, as well as coastal sequences in New Zealand in general, a coastal diatom calibration set was constructed using 50 sites around New Zealand. Modern diatom distribution and abundance, and associated environmental variables are analysed using ordination and weighted averaging techniques. Detrended correspondence analysis arranges species according to salinity preferences and divides sites clearly into waterbody types along a coastal gradient. This analysis enables reconstruction of waterbody type from fossil samples by passive placement onto ordination diagrams. Weighted averaging regression of calibration set samples results in a high correlation (r2jack=0.84) between observed and diatom inferred salinity, and enables salinity preferences and tolerances to be derived for 100 species. This confirms for the first time that species' preferences derived in the Northern Hemisphere are generally applicable to diatoms living in the coastal zone of New Zealand. Weighted averaging calibration and the modern analogue technique are used to generate quantitative estimates of paleosalinity for fossil samples. Paleoenvironmental reconstructions of Taupo Swamp, Okupe Lagoon and Lake Kohangapiripiri indicate that each waterbody has been isolated from the sea during the late Holocene. Isolation has been achieved through interplay of sediment accumulation causing growth of barrier beaches, and coseismic uplift. Ten distinct transitions between different paleoenvironments are recognised from the three sequences. These transitions involve changes in relative sea level or water table level often in association with catchment disturbance or marine influx events. All transitions occur suddenly and are laterally extensive and synchronous within each waterbody. Quantitative estimates of paleosalinity and waterbody type are used to differentiate between large and small magnitude changes in paleoenvironment. Five transitions involve large amounts of paleoenvironmental change and provide evidence for earthquakes occurring at approximately 5200, approximately 3200, and approximately 2300 cal. years BP. Five other transitions are consistent with the effects of large earthquakes occurring at approximately 6800, 2200, approximately 1000, approximately 500 cal. years BP and 1855 AD but do not provide independent evidence of the events. Environmental transitions at Lake Kohangapiripiri clarify the timing of rupture of the Wairarapa Fault by bracketing incompatible age estimates derived from two different sites on the fault. The oldest environmental transitions recognised at Taupo Swamp and Okupe Lagoon both occur at approximately 3200 cal. years BP indicating that western Wellington was uplifted at this time. Environmental transitions are recorded at all three study sites at approximately 2300 cal. years BP indicating that the entire western and central Wellington region experienced coseismic uplift at this time. Because of the distance between sites this apparent synchroneity implies that several faults in the region ruptured at a similar time. Investigation of sedimentary sequences contributes to the existing paleoseismic record by providing additional estimates of timing for past large earthquakes, enabling estimation of the areal extent of the effects of past earthquakes, and by highlighting periods of fault rupture activity in the late Holocene.

    View record details
  • "Where the Nightmares End and Real-Life Begins": Radical Unreliability in Sydney Bridge Upside Down

    Clayton, Hamish (2017)

    Doctoral thesis
    Victoria University of Wellington

    The unreliable narrator is one of the most contested concepts in narrative theory. While critical debates have been heated, they have tended to foreground that the problem of the unreliable narrator is epistemological rather than ontological: it is agreed that narrators can be unreliable in their accounts, but not how the unreliable narrator ought to be defined, nor even how readers can be expected in all certainty to find a narration unreliable. As the wider critical discourse has looked to tighten its collective understanding of what constitutes unreliability and how readers understand and negotiate unreliable narration, previously divided views have begun to be reconciled on the understanding that, rather than deferring to either an implied author or reader, textual signals themselves might be better understood as the most fundamental markers of unreliability. Consequently, taxonomies of unreliable narration based on exacting textual evidence have been developed and are now widely held as indispensable. This thesis argues that while such taxonomies do indeed bring greater interpretive clarity to instances of unreliable narration, they also risk the assumption that with the right critical apparatus in place, even the most challenging unreliable narrators can, in the end, be reliably read. Countering the assumption are rare but telling examples of narrators whose reliability the reader might have reason to suspect, but whose unreliability cannot be reliably or precisely ascertained. With recourse to David Ballantyne’s Sydney Bridge Upside Down, this thesis proposes new terminological distinctions to account for instances of such radical unreliability: namely the ‘unsecured narrator’, whose account is therefore an ‘insecure narration’. Ballantyne’s novel, published in 1968, has not received sustained critical attention to date, though it has been acclaimed by a small number of influential critics and writers in Ballantyne’s native New Zealand. This thesis argues that the novel’s long history of neglect is tied to the complexities of its radically unreliable narration. With social realism the dominant mode in New Zealand literature from the 1930s to the 60s, the obligation of the writer to accurately render—and critique—local conditions with mimetic accuracy was considered paramount. Even those critics to have argued the novel’s importance often maintain, largely or in part, a social realist view of the book’s significance. Doing so, however, fundamentally elides the complexity of the novel’s narrative machinery and to deeply ironic ends: for, this thesis argues, Sydney Bridge Upside Down deploys its insecure narration as a complaint against the limits of social realism practised in New Zealand. Its unsecured narrator, Harry Baird, slyly overhauls realist reference points with overtly Gothic markers and cunning temporal dislocations to thus turn social realism’s desire for social critique back on itself via radical unreliability.

    View record details
  • Assessing the Vulnerability and Resilience of the Philippines to Disasters

    Yonson, Rio (2017)

    Doctoral thesis
    Victoria University of Wellington

    Some of the world’s most destructive disasters occurred in the Philippines, and a number of these happened in recent years. In 2011, 2012, and 2013, tropical cyclones Washi, Bopha, and Haiyan, respectively, left a staggering trail of over 8,000 deaths, as well as huge damages to assets and livelihoods. In 2009, tropical cyclones Ketsana and Pharma brought massive riverine floods, with a total damage and loss equivalent to 2.7% of the country’s GDP. This dissertation is an endeavour to measure disaster impacts and welfare risk, and to identify factors affecting vulnerability and resilience in different spatial scales in the Philippines. The first of four chapters is an extensive literature survey on the economic vulnerability and economic resilience to disasters. This serves as a prelude to the succeeding three empirical studies contained in Chapters 3 to 5. Chapter 3 aims to measure tropical cyclone-induced fatalities in the Philippine provinces, and identifies the factors that shape people’s vulnerability. It also quantifies the relative importance of hazard, exposure, and socioeconomic vulnerability in influencing fatalities. Chapter 4 is a household level study that quantitatively establishes the linkages between floods and diseases in the floodplains of a highly-urbanized city in the Philippines (Cagayan de Oro), and provides an estimate on the public finance implications of flood-induced diseases to the Philippine urban areas, and on the additional economic burden on affected households. Chapter 5 measures socioeconomic resilience and welfare risk from riverine flood disasters, and systematically quantifies the effectiveness of a menu of region-specific disaster risk reduction and management measures.

    View record details
  • Particle Swarm Optimization and Fuzzy C-means for Domain-independent Noisy Image Segmentation

    Mirghasemi, Saeed (2017)

    Doctoral thesis
    Victoria University of Wellington

    Image segmentation is considered to be one of the foremost image analysis techniques for high-level real-world applications in computer vision. Its task is to change or simplify the representation of an image in order to make it easier to understand or analyze. Although image segmentation has been studied for many years, evolving technology and transformation of demands make image segmentation a continuing challenge. Noise as a side effect of imaging devices is an inevitable part of images in many computer vision applications. Therefore, an important topic in image segmentation is noisy image segmentation which requires extra effort to deal with image segmentation in the presence of noise. Generally, different strategies are needed for different noisy images with different levels/types of noise. Therefore, many approaches in the literature are domain-dependent and applicable only to specific images. A well-recognized approach in noisy image segmentation uses clustering algorithms, among which Fuzzy C-Means (FCM) is one of the most popular. FCM is unsupervised, efficient, and can deal with uncertainty and complexity of information in an image. Dealing with uncertainties is easier with the fuzzy characteristic of FCM, and complexity of information is being taken care of by utilizing different features in FCM, and also combining FCM with other techniques. Many modifications have been introduced to FCM to deal with noisy image segmentation more effectively. Common approaches include, adding spatial information into the FCM process, addressing the FCM initialization problem, and enhancing features used for segmentation. However, existing FCM-based noisy image segmentation approaches in the literature generally suffer from three drawbacks. First, they are applicable to specific domains and images, and impotent in others. Second, they don’t perform well on severely noisy image segmentation. Third, they are effective on specific type and level of noise, and they don’t explore the effect of noise level variation. Recently, evolutionary computation techniques due to their global search abilities have been used in hybridization with FCM, mostly to address FCM stagnation in local optima. Particle Swarm Optimization (PSO) is particularly of interest because of its lower computational costs, easy implementation, and fast convergence, but its potential in this area has not been fully investigated. This thesis develops new domain-independent PSO-based algorithms for an automatic non-supervised FCM-based segmentation of severely noisy images which are capable of extracting the main coherent/homogeneous regions while preserving details and being robust to noise variation. The key approach taken in the thesis is to explore the use of PSO to manipulate and enhance local spatial and spatial-frequency information. This thesis introduces a new PSO feature enhancement approach in wavelet domain for noisy image segmentation. This approach applies adaptive wavelet shrinkage using evaluation based on FCM clustering performance. The results show great accuracy in the case of severe noise because of the enhanced features. Also, due to adaptivity, no parameter-tuning is required according to the type or volume of noise, and the performance is consistent under noise level variation. This thesis presents a scheme under which a fusion of two different denoising algorithms for more effective segmentation is possible. This fusion retains the advantages of each algorithm while leaving out their drawbacks. The fusion scheme uses the noisy image segmentation system introduced above and anisotropic diffusion, the edge-preserving denoising algorithm. Results show greater accuracy and stability in comparison to the individual algorithms on a variety of noisy images. This thesis introduces another PSO-based edge-preserving adaptive wavelet shrinkage system using wavelet packets, bilateral filtering, and a detail-respecting shrinkage scheme. The analysis of the results provide a comparison between the two feature enhancement systems. The first system uses wavelets and the second uses wavelet packets as a domain to enhance features for an FCM-based noisy image segmentation. Also, the highest segmentation accuracy among all the algorithms introduced in this thesis on some benchmarks belong to this system.

    View record details
  • Social networks, identity and contexts : a narrative ethnography of a group of College English (CE) teachers’ social learning process amid the research discourse.

    Zeng, Wei (2017)

    Doctoral thesis
    University of Canterbury Library

    This research is a narrative ethnography about a group of College English (CE) teachers working at a university in China. As one of them, I, together with my CE colleagues, lived and told our stories of dealing with the increasing research demand from the workplace. I sought to explore how our workplace mediated the social process of our learning during educational change. The research is conceptualized within the theoretical framework of community of practice and draws on social network perspective. It also adopts a poststructuralist perspective to present the dynamic socio-cultural process of how these teachers experienced and made meaning of various discourses about their teaching, researching and personal lives. The discourses from the workplace, the social context and teachers themselves make these CE teachers’ social networks and identities a site of ambivalence and struggles. Entrenched in a lower-status department, CE teachers struggled with various meanings of knowledge: the officially-valued research, the teaching-research, linguistics/western literature research, non-linguistics/western literature research, quantitative research and qualitative research. They also grappled with competing duties from both the workplace and the family. The research delves into CE teachers’ lived experiences, offering implications for enhancing CE teachers’ learning as well as international understanding of academics who might experience similar educational change. Finally, the study contributes to advancement of social learning theories, in particular, the theory of community of practice and social network theories.

    View record details
  • Advocacy for Using Evidence in Public Health Nutrition Policy Making

    Field, Penelope Anne (2014)

    Doctoral thesis
    University of Otago

    Do advocates for using evidence make a difference? A case study of public health nutrition policymaking in New Zealand. There is a growing body of evidence supporting interventions that will effectively address nutrition-related non-communicable disease. However, researchers and other stakeholders often despair that such evidence is not informing government policy. The emerging field of ‘evidence-informed’ policy addresses the question, ‘What works?’ to improve the use of evidence in policymaking. This thesis aims to contribute to this enquiry by exploring how advocates for the use of evidence can make a difference. Advocacy can connect science, society and politics and build ‘multiple footbridges’ between the worlds of decision makers and those who generate evidence. A theoretical model for advocacy for evidence use was developed following an extensive literature review. The model was evaluated against a rival explanation in a policy case study of food marketing to children. Data were collected by interviews with senior members of the New Zealand public health nutrition policy community, documentary analysis and field notes. Results indicate that current policymaking systems are ad hoc and non-deliberate, informal relationships are the primary channel by which evidence informs bureaucrats’ decision making and the powerful role of meta-level policy is largely unknown. Major determinants of advocacy activity are access to resources and the opportunities presented by political timing. Concurrently the trend for sovereign government to be replaced by governance mechanisms and a government agenda to give science a greater role in policymaking are shifting established policy processes. These factors, together with a growing realisation that public health nutrition policymaking needs a paradigm shift, are creating opportunities for advocacy for the use of evidence. The findings of this research lead to the conclusion that public health nutrition policy processes will deliver better outcomes when the ‘idea’ of using evidence is actively advocated. Politically aware advocacy should enhance evidence use when it brings about shifts in meta-level policy, policymaking processes and relationships across the policy community.

    View record details
  • Coherent Frequency Conversion from Microwave to Optical Fields in an Erbium Doped Y2SiO5 Crystal: Towards the Single Photon Regime

    Fernandez Gonzalvo, Xavier (2017)

    Doctoral thesis
    University of Otago

    In the context of quantum information technologies superconducting qubits (SQs) are very attractive devices for the manipulation of quantum states, and present themselves as one of our best candidates to build a quantum processor. They couple naturally to microwave photons, for which suitable quantum memories or a long distance propagation channel don’t exist. A way around these limitations is to turn these microwave photons into optical ones by building a quantum frequency converter: a device by which the frequency of a photon can be changed while preserving its non-classical correlations. Then, optical fibres could be used to link distant SQ-based devices together, facilitating the creation of a network of quantum computers. Moreover, SQs could then be coupled to quantum memories compatible with photons at optical frequencies, which are the most well developed kind of quantum memories at the present time. This thesis explores the possibility to convert single microwave photons into optical photons using erbium doped in a yttrium orthosilicate crystal (Er3+:Y2SiO5). Er3+:Y2SiO5 is a good candidate because it has a naturally occurring optical transition near 1536 nm close to the point where silica optical fibres show their minimum loss. A microwave transition can be found in two different ways: one way is to use the 167 isotope of erbium, which is the only stable isotope that shows hyperfine splitting as it has non-zero nuclear spin. The hyperfine structure of the ground state of 167Er3+:Y2SiO5 spans over about 5 GHz. The other possibility is to use the other stable isotopes of erbium and Zeeman split their ground state using an external magnetic field. A microwave transition near 5 GHz can be achieved with moderate magnetic fields due to the high ?-factors of Er3+:Y2SiO5. The physical process of interest is a three wave mixing process involving two fields at optical frequencies and one field at microwave frequencies. In order to boost the efficiency of the frequency conversion process the Er3+:Y2SiO5 crystal is placed inside a microwave and an optical resonator. The problem is first explored from the theoretical point of view, where a nonlinear coefficient Λ(2) is derived (analogous to the ?(2) often used in nonlinear optics), and the interaction between cavity modes and the nonlinear medium is studied. It is predicted that with a sample cooled down to millikelvin temperatures total frequency conversion between microwave and optical fields can be achieved. A preliminary hole burning spectroscopy experiment is performed with the objective of reconstructing the hyperfine structure of the excited state of 167Er3+:Y2SiO5, but the complexity of the problem makes it too difficult to achieve this goal. Then a series of experiments are shown, aimed at determining whether or not frequency conversion at the single photon level is achievable using the even isotopes of erbium in a magnetic field. These experiments are based in the Raman heterodyne spectroscopy technique, which is used in combination with electron paramagnetic resonance and optical absorption spectroscopy. In all experiments the sample is cooled down to cryogenic temperatures near 4 K. A first experiment shows that the frequency conversion process exists in Er3+:Y2SiO5, in a setup where only a microwave resonator is used, but not an optical one. A second experiment is performed in a similar setup, this time presenting a quantitative study of the properties of the frequency conversion process, and its comparison with the theoretical model previously derived. A third experiment is performed, which incorporates an optical cavity to the system. The interaction between the erbium ions and the optical cavity introduces a whole new range of experimental complications, which are studied and discussed. Then, the frequency conversion signal is studied anew, showing an unexpected highly non-linear scaling behaviour with the input powers. A hypothesis explaining this unexpected behaviour is given, referring to stray optical absorption in the inhomogeneous line of Er3+:Y2SiO5 (and in particular 167Er3+:Y2SiO5), which can be bleached out under certain circumstances due to spectral hole burning effects. The overall maximum frequency conversion efficiency observed is of 3 × 10^−4 per Watt of pump laser power. While this value is still far from the target several ways of improvement are proposed, including cooling down the system to millikelvin temperatures, increasing the dopant concentration and modifying the geometry of the resonators.

    View record details
  • Measurements and modelling of eutrophication processes in Lake Rotoiti, New Zealand

    von Westernhagen, Nina (2010)

    Doctoral thesis
    University of Waikato

    Deterioration of water quality is a common problem for aquatic systems globally, which is accelerated by factors such as urban settlement, farming, forestry and recreation. Spatial variability of water quality in these systems hinders a more advanced understanding of their dynamics, to better enable strategies to be developed to combat their deterioration. Understanding the drivers for spatial variability is fundamentally important for predicting how lake ecosystems will respond to management scenarios and which management actions are most likely to be successful to improve lake health. Through a field study in a morphologically diverse lake in New Zealand, and the application of a lake ecosystem model, this study examined the spatial and temporal variability of phytoplankton biomass and made a detailed consideration of the performance of three-dimensional lake ecosystem models. To gain insight in the spatial variability in phytoplankton productivity, surface phytoplankton productivity measurements were carried out at three stations in morphologically complex Lake Rotoiti, North Island, New Zealand, with the objective of defining variations between sites and seasons, and the dominant environmental drivers of these variations. There was no overarching statistical relationship between measured environmental variables and primary productivity or specific production. Inorganic nutrient concentrations at the surface of the shallow station were low throughout the whole year but at the other two stations they showed a typical pattern for monomictic lakes of higher levels during winter mixing and declining concentrations during thermal stratification. The high variability between the three sites indicates that it is important to account for local differences in productivity in morphologically diverse lakes, and that whole-lake productivity estimates may vary greatly depending on the location and depth at which measurements are made. To gain understanding of the spatial variability, a higher resolution three-dimensional (3D) model, ELCOM-CAEDYM, was used to simulate the time-varying horizontal and vertical variations in water quality over one year (May 2004-May 2005). The main inflow to Lake Rotoiti arises via the Ohau Channel from adjacent eutrophic Lake Rotorua. Highly spatially resolved field data were collected monthly to validate the model performance for simulations of temperature, dissolved oxygen and chlorophyll a. The model was configured to simulate a geothermal heat source in the deepest part of the main lake basin. Model simulations of temperature, dissolved oxygen and chlorophyll a were highly correlated with measurements of these variables but simulations of spatial variations in nutrient concentration showed relatively low correlation coefficient values, in particular at a station located in a shallow embayment. An examination of the behaviour of a conservative tracer introduced into the major inflow of Lake Rotoiti, the Ohau Channel, confirmed previous findings that this inflow could enter the lake as a surface inflow, interflow or underflow, depending on temperature gradients between the inflow and the lake water column. The results showed that ELCOM-CAEDYM is capable of reproducing highly spatially resolved field data in a complex, geothermally-influenced lake, and can provide important insights into the fate of heat and constituents in major inflows. A wall to divert Ohau Channel water directly towards the outflow of Lake Rotoiti was implemented in August 2008. Based on parameter values calibrated for the time period before the inflow diversion (May 2004-May 2005), ELCOM-CAEDYM was applied to the post-diversion wall period of August 2008-August 2009. The model showed good fit with observed data for temperature, dissolved oxygen and chlorophyll a, but the model showed a poor fit when simulations were compared with in situ nutrient concentrations at all stations. Simulations with ELCOM-CAEDYM suggest that model accuracy may be improved when a simplified dynamic sediment diagenesis model is available. This could provide for less sensitivity to sediment nutrient release rates of the model and better model fit to in situ data. Ecosystem modelling is likely to play an increasingly important role in lake management and scientific understanding of lake processes as computer speed increases and models undergo further refinements. The model development is in a phase of relative maturity in which water quality simulations provide an efficient and rational tool to compare water quality outcomes and cost effectiveness of lake improvement techniques, to provide for preservation and improvement in water quality in the future.

    View record details
  • Food webs in the lower Waikato River and the role of hydrogeomorphic complexity

    Pingram, Michael Alister (2014)

    Doctoral thesis
    University of Waikato

    Large rivers are fundamental to human societies and consequently their ecosystems have come under increasing pressure from a range of developments and uses. Despite this, there is still a major knowledge gap understanding food webs supporting fisheries of large river ecosystems. Quantifying the contributions of carbon sources that support food webs is an important and growing field of ecological research, with implications for future management and rehabilitation of large rivers. I reviewed theoretical concepts addressing carbon flow in large river food webs where organic matter from floodplains (Flood Pulse Concept), local aquatic sources (Riverine Productivity Model), or leakage from upstream processing of terrestrial organic matter (River Continuum Concept) can fuel secondary production. Recent empirical evidence highlights the importance of autochthonous carbon, especially in the form of benthic algae and phytoplankton, to food webs in a variety of large rivers along with a range of secondary carbon sources that can assume importance depending on temporal and spatial variation in hydrogeomorphic conditions. The geographic spread of studies addressing carbon flow in large river food webs is steadily increasing, although information remains sparse on temperate Southern Hemisphere rivers and long-term data sets on carbon flow are generally lacking. I measured natural abundances of stable carbon (δ13C) and nitrogen (δ15N) isotopes to quantify spatial and temporal patterns of carbon flow through aquatic food webs in the lowland section of New Zealand’s longest river, the Waikato River. Zones of potential ecological importance influencing carbon transfer along the lower Waikato River were identified using a combination of (i) high-frequency, along-river water quality measurements collected during four seasons and (ii) river channel morphology data derived from aerial photos. A multivariate statistical approach was developed to identify three hydrogeomorphic zones shaped by the physical complexity and channel character of constituent river reaches, and characterised by shifts, sometimes transitional, of physico-chemical variables. Changes in water clarity, chlorophyll fluorescence and specific conductance were driven by tributary inflows and tidal influence. Carbon flow estimated using the mixing model IsoSource supported predictions of the Riverine Productivity Model, with autochthonous algae and biofilms (phytomicrobenthos) the most important basal carbon sources contributing to consumer biomass in all three zones. These sources were often supported by C3 aquatic macrophytes and allochthonous C3 riparian plants. However, the relative importance of organic carbon sources appeared to change depending on season and zone, likely in response to variations in water temperature and flow, particularly in the unconstrained zone of the lower river. It was also demonstrated that to draw robust conclusions, consideration must be given to quantifying the isotopic signatures of organisms lower in the food web, as these can change significantly between sampling times and hydrogeomorphic zones. Tributary confluences can be hotspots for biological production and provide novel carbon sources from donor sub-catchments in large river systems. Littoral food webs and water quality were compared between two main stem habitats (constrained and unconstrained hydrogeomorphic zones) and tributary junctions representing those fed by streams, lakes and wetlands during seasonal low flows when these habitats were likely to be most different. δ13C and δ15N isotopes were then employed using the Bayesian statistics R package Stable Isotope Analysis in R (SIAR) to estimate carbon flow through food webs and also to estimate measures of trophic structure. Pathways were also tested using analysis of fish stomach contents. SIAR mixing models confirmed that autochthonous benthic carbon was the most important carbon source to littoral food webs in all habitats. Riparian carbon appeared to be the most important secondary carbon source to fish consumers, and estimates of its contribution were often greater in tributary junctions compared to fish of the same species in the main stem. Trophic patterns of fish species collected in both the main stem and tributary junctions were similar amongst habitats, as were community metrics estimated using stable isotope signatures and SIAR. This study demonstrates that, while they may add to the lateral complexity of the riverscape, permanently connected habitats such as tributary junctions do not necessarily contribute to overall food web complexity. In this study tributary junctions tended to be steep-sided, and complex littoral habitats containing woody debris and macrophytes were typically rare, potentially limiting the development of more complex food webs. These results contribute to the ever-improving data regarding food web ecology in large rivers, particularly with regard to carbon flow, and the role played by lateral habitats and hydrogeomorphic zones in shaping these processes. This study also provides information and recommendations that provide direction for future research and management actions aimed at aiding the rehabilitation of the lower Waikato River, its riverscape and biological communities.

    View record details
  • Teacher Education ICT Appropriation Model TEAM: A Model for ICT Appropriation in Early Childhood Initial Teacher Education

    Merry, Rosina (2017)

    Doctoral thesis
    University of Waikato

    Early childhood initial teacher education programmes are only beginning to use information and communication technology (ICT) as part of their curriculum. There is limited research or practice knowledge about how student teachers learn to use ICT for pedagogical purposes. This doctoral study investigated how student teachers might be supported to appropriate and integrate ICT into their developing teaching practice. The study endeavours to understand the experiences of student teachers and practising early childhood teachers. The 230 student teachers in the study were from one university in New Zealand that offers early childhood initial teacher education (ITE). The study utilised interpretative, qualitative methodology. Data were collected over two years with two cohorts of student teachers who were engaged in online discussions in the course of their ITE studies. Thirty-three practising early childhood teachers participated in semi-structured interviews. The online discussions and the interviews provided the material for analysis. Analysis took the form of thematic analysis. The key outcome from this study is the development of the Teacher Education ICT Appropriation Model (TEAM). This is a theoretical model for what is needed to support student teacher and teacher use of ICT. The model is underpinned by a sociocultural view of learning and acknowledges and responds to the social nature of teaching and learning. The model includes key elements – subjective norms, relational trust, ICT cultural tools and enjoyment – as central to creating a sociocultural pedagogical place and space for ICT use. It also takes into account the influence of policy, curriculum and assessment on teaching and learning. Findings indicate these elements are all interrelated in the successful development of effective pedagogy. The thesis argues that, when curriculum takes a sociocultural perspective on learning, ITE must do so as well. This means that, where ITE includes introducing tertiary students to teaching with and through ICT, sociocultural elements must be taken into account and frame up ITE. This thesis sets out just such a frame.

    View record details