Doctoral Theses

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The Doctoral Theses collection contains digital copies of AUT doctoral theses deposited with the Library since 2004 and made available open access. All theses for doctorates awarded from 2007 onwards are required to be deposited in Tuwhera Open Theses unless subject to an embargo.

For theses submitted prior to 2007, open access was not mandatory, so only those theses for which the author has given consent are available in Tuwhera Open Theses. Where consent for open access has not been provided, the thesis is usually recorded in the AUT Library catalogue where the full text, if available, may be accessed with an AUT password. Other people should request an Interlibrary Loan through their library.

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    Insulinaemia During Pregnancy and Implications for the Dietary Management of Gestational Diabetes Mellitus
    (Auckland University of Technology, 2024) Goedeke, Sylvia Michelle
    Amid the global obesity and type 2 diabetes epidemic, insulin resistance among women of child-bearing age continues to increase. Pregnancy is a natural state of insulin resistance and increased insulin secretion. When the physiological changes of pregnancy are superimposed on pre-existing insulin resistance, metabolic changes associated with pregnancy can become exaggerated. This can lead to an environment characterised by nutrient excess and inflammation, which is associated with adverse pregnancy conditions such as gestational diabetes mellitus (GDM) and foetal overgrowth. In the field of diabetes research, i.e. as a context separate from pregnancy, there has been growing interest in chronically elevated insulin, termed hyperinsulinaemia, and the role it plays in the aetiology of various cardiometabolic conditions. In this context, according to The Kraft Model of Hyperinsulinaemia, an elevated fasting and/or post-glucose load (100-gram glucose) plasma insulin response may be one of the earliest indicators for the development of type 2 diabetes later in life. While these concepts cannot be directly applied to pregnancy, it is likely that many women of child-bearing age will enter pregnancy with pre-existing insulin resistance and hyperinsulinaemia. As such, this may lead to further exaggerated changes in maternal metabolism (i.e. in the form of glucose, lipids, amino acids, and inflammatory markers). Moreover, since women who experience adverse pregnancy outcomes such as GDM appear to exist on a more adverse track toward later life chronic metabolic diseases, it is hypothesised that identifying hyperinsulinaemia (according to The Kraft Model) during pregnancy may aid in identifying these at-risk women sooner in pregnancy. Such early identification could provide an opportunity to enhance lifestyle management to mitigate the exaggeration of metabolic changes associated with pregnancy. The overarching aim of this body of work was to investigate the relationship between insulin response patterns during pregnancy and adverse pregnancy outcomes. A further aim was to explore current dietary advice for the management of GDM. To investigate this aim, the first study was a systematic review (15 articles from 11 randomised controlled trials (RCTs), n = 3,614 participants) to extend knowledge on dietary interventions during pregnancy that may be effective for reducing the risk of adverse perinatal outcomes linked to maternal metabolic dysfunction (Chapter 3). The primary outcomes were neonatal cord blood insulin, c-peptide, and adiposity as markers of foetal hyperinsulinaemia and overnutrition. Findings demonstrated an overall protective effect of lifestyle-based interventions (including nutrition, physical activity, behaviour change, and monitoring) with elements of personalisation and dietary advice based on low glycaemic load (GL) approaches for reducing neonatal adiposity. Maternal insulin response patterns and the prevalence of hyperinsulinaemia (applying the Kraft algorithm) according to varying degrees of glucose tolerance were then investigated in an observational study (Chapter 4). For this study, a historical dataset, dated mid-1970s to early-1990s, of results from presumed pregnant women (n = 926) who underwent three-hour oral glucose tolerance tests (OGTTs, 100-gram glucose load) with insulin assays was examined. Demographic information available included only participant age, weight, height, and date of testing. Further medical information and gestational age at time of testing was not available. Almost a third (31%) of the women with normal glucose tolerance demonstrated a delayed peak hyperinsulinaemia pattern (Kraft pattern III). Among the women with GDM (2010 American Diabetes Association criteria), the prevalence of Kraft pattern III hyperinsulinaemia was 75%. Kraft pattern IV hyperinsulinaemia was only observed in 3% of participants, the majority of which were categorised as GDM (GDM vs. normal: n = 13, 6% vs. n = 9, 1.5%; p<0.001). To further explore the relationship between early pregnancy insulin response patterns and changes later in gestation, a case series of four pregnant women living in New Zealand was conducted (Chapter 5). Participants underwent an OGTT (75-gram glucose, 2-hour) at ≤ 14 weeks’ gestation. Insulin response patterns were defined using a modified version of the Kraft algorithm to include four plasma insulin and glucose samples from the OGTT (fasting and 30-, 60-, and 120-minutes post oral glucose). Glycaemic measures, weight gain, foetal growth, dietary and lifestyle changes, and obstetric outcomes were examined throughout pregnancy. Two cases presented with Kraft pattern IIB hyperinsulinaemia early in pregnancy. For both of these women, difficulty during labour was observed (shoulder dystocia and surgically assisted delivery for Case #1, and emergency caesarean section for Case #4). A protective effect of healthy lifestyle choices to limit gestational weight gain (GWG) was postulated. The final component of this research explored the current lifestyle management of GDM pregnancies by maternity-based health professionals in New Zealand in a qualitative study (Chapter 6). Key barriers to providing dietary advice included limited accessibility of health services, service delivery issues, fragmentation and conflicting information across health providers and alternative information sources (e.g. internet-based), and gaps in nutrition guidelines and clinical resources. Collectively, this body of work demonstrated the potential significance of using insulin response patterns to recognise hyperinsulinaemia early in the gestational period. Several gaps in care were highlighted around the dietary management of women during early gestation at risk of GDM and those later in pregnancy once diagnosed. Recognising a spectrum of insulin response patterns may help to identify metabolic dysfunction much sooner in pregnancy than current screening programmes. Earlier identification of women with such an increased risk could further enhance dietary and lifestyle management to be more proactive and personalised. Further research into this area could help inform the development of early screening tools for women with a higher risk of adverse outcomes and guide treatment decisions. In practice, a better understanding of metabolic phenotypes may aid in progressing therapeutic dietary advice to become more targeted and personalised for better maternal and offspring outcomes.
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    Alkali Activated Materials (AAMs) as Concrete Repair Materials
    (Auckland University of Technology, 2023) Mohd Yusslee, Eddy Mohd Fairuz
    Alkali Activated Materials (AAMs) is a new cement technology utilizing waste products to produce cementitious binders. The main precursors are activated with an alkali activator for the hardening process. The reaction between precursors and alkali activator will create hydrated gels of calcium aluminate silicate hydrates, C-A-S-H and/or sodium aluminate silicate hydrates, N-A- S-H for binding phases. FA and GGBFS contain a high amount of silica and alumina in their chemical components, thus making them suitable sources as aluminosilicate precursors for cement binders. AAMs are traditionally employed in the two-part system where the activator is liquid and activated dry precursor powder. However, it has handling problems due to corrosive activators that may affect worker safety, besides some performance issues such as rapid setting time and higher shrinkage issues that limit their application at real-site construction. Including ordinary Portland cement (OPC) mixed with aluminosilicate precursors, also known as hybrid, is an effort to modify the engineering properties of the dry mixture materials in one-part AAMs (dry activator system) in this study, diversifying its potential application. One-part AAMs technology mainly focuses on concrete product purposes as an alternative to conventional OPC-based cementitious. A hybrid one-part AAMs mortar is being developed to reduce dependency on OPC in the form of mortar and cut the OPC volume as low as possible. Interestingly, the mechanical strength of the hybrid one-part AAMs mortar developed in this research is comparable to the OPC concrete, providing extra added value where no coarse aggregate is used, which the construction sector responsible for the waning of natural resources and environmental imbalances due to mining activities/rock excavations. In this studies, all mortar samples were tested in the laboratory with controlled room temperature (18 – 22°C) and relative humidity, RH > 90%, to comply with EN1504–3:2005 standard, part 3: structural and non-structural concrete repair materials. The novel mix design formulation confirms it successfully replaces 30% of OPC volume with industrial by-product precursors as the first step in diminishing reliance on the OPC and another effort to reduce clinker production, reuse waste products, and control CO2 emissions. Nevertheless, using a less reactive alkaline activator with a low concentration level is beneficial for a cheaper cost, lower health risks and is not harmful to the environment. The hybrid one-part AAMs mortar in this study has mechanical strength that complies with European standards, EN-1504 specifications for Class R4 – Structural concrete repair materials. It has also had improved pore volume structures that reduce the porosity level – main drawbacks for one-part AAMs system while providing better engineering properties and durability for long-term applications. One-part AAMs repair mortar as new innovative construction materials achieved another milestone as an effort to improve the construction sector towards the goal of sustainable construction to keep global warming increased to no more than 1.5 Celsius as called for in the Paris Agreement – emissions need to be reduced by 45% by 2030 and reach net zero by 2050 and also particularly for the zero carbon target in New Zealand - for domestic targets under the Climate Change Response Act (CCRA) Net zero emissions of all greenhouse gas (GHG) emissions other than biogenic methane by 2050.
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    Exploring Tertiary Students’ Mathematical Modelling Experiences: Insights for Practice
    (Auckland University of Technology, 2023) Spooner, Kerri
    The purpose of this study is to investigate tertiary student learning experiences for mathematical modelling. This study is based in New Zealand and involves three different tertiary modelling courses. For students participating in these modelling courses, this was their first time studying modelling at tertiary level. This study uses Interpretive Description as the methodology to look at the student experience with the aim of establishing a better understanding of student experiences with mathematical modelling, the role the lecturer plays in these experiences, and how any new insights can better inform teaching practices. This study aims: to provide new insights and understandings of the student perspective to inform and advance tertiary teaching practices; to gain a deeper understanding of the lecturer’s role in the student experience; to contribute to the general discussion on how to provide rich student learning experiences in mathematical modelling; and to inform the general discussion for students to be able to contribute to society through mathematical modelling. One overarching theme and three subthemes were constructed from the data. The overarching theme pushing our boundaries, captures how all students had experiences that are new, unfamiliar, and outside their normal range of experiences with mathematics while mathematically modelling. Subtheme one, moving forward on our own, captures how students needed to learn how to move forward on their own in order to make progress. Moving forward involved taking responsibility, both individually and as a group, to actively find ways forward. Subtheme two, being moved forward, focusses on the use of resources and the lecturer’s role in moving students forward, while also enabling student groups to work independently of the lecturer. Subtheme three, going forward together as a collective, captures the interwoven and collective nature of learning to mathematical model. This research shows how modelling is a change of culture for students and the lecturer has a role to play. This research presents nuances of the dynamics between independent student work and the lecturer’s role. The findings of this study suggest students can undertake modelling without the lecturer or teacher being present if they have prepared for the experience beforehand and have access to appropriate resources. Lecturer behaviours that help students to take responsibility for their own modelling process include: providing students with material to refer to; using facilitatory questions/prompts aligned with the modelling process; and creating environments for students to share their thoughts and workings. Lecturer support needs to allow for students to experience struggle, explore, be creative and become self-reliant. Experiencing these key student behaviours allows students to move from being uncertain to finding direction and thus take responsibility and ownership for their own modelling process. Implications of this research for general mathematics education practices include the suggestion of lecturers and teachers incorporating connecting mathematics to context as a normal part of their teaching practice and develop a learning environment where being uncertain and the need for exploration is a normal part of learning mathematics.
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    Digital Financial Services: Unveiling the Collective Potential in Rural Landscape of India
    (Auckland University of Technology, 2024) Sharma, Himanshu
    Access to financial services not only has the potential to ignite economic prospects but also supports human development. The progress of information and communication technologies (ICTs) has significantly improved the accessibility, security, speed, and affordability of financial services, all thanks to the advent of ICTs. Prior research has predominantly centred on the implementation, deployment, and adoption of digital financial services (DFS), but the aim of this study diverges from this established focus. This qualitative and interpretive research examines how individuals in rural areas leverage DFS to achieve life goals. The research fieldwork of this study focuses on rural areas in the Uttar Pradesh (UP) state of India. Data collection using ethnographic techniques is conducted in seven villages within two districts of UP state: Gautam Buddha Nagar (GBN) and Bulandshahr (BS). The sample comprises thirty-six interviews, serving as the data set for the thematic analysis guided by an inductive-abductive reasoning approach. This blended method is embraced to identify core themes and extract novel insights into the role of DFS’s contribution to people’s lives. The thematic analysis revealed three core themes. The first two themes of this study contribute to existing knowledge about the instrumental role of DFS in expanding an individual's economic opportunities and financial literacy. The third theme challenges the conventional DFS perspective. It emphasises the DFS's potential to cultivate a pro-social environment where individuals share DFS resources, such as knowledge, skills, and applications. The mapping of core themes with extant theories unveils a conceptual DFS use continuum, symbolising two interrelated poles: the personal use of DFS and the collective use of DFS. Theoretical insights indicate that DFS can facilitate the development of a collaborative support system through the involvement of active DFS users in the closely-knit fabric of social networks. This study has practical implications, particularly for banking institutions to understand the social capital dynamics, identify active DFS users within communities across their operational zones, and offer them specialised training programmes to strengthen the DFS ecosystem.
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    Interference Mitigation in D2D-enabled Heterogeneous Cellular Networks
    (Auckland University of Technology, 2023) Kamruzzaman, Md
    Device-to-Device (D2D) communication is a promising technology for next generation cellular networks. The D2D communication is being considered for the LTE Advanced standards in 3GPP Release 12, as Proximity Services (ProSe) continue to be part of current 5G or beyond cellular networks to support diverse applications. To fulfil the QoS requirements and to overcome the challenges of beyond 5G (B5G) cellular networks, D2D communication plays an important role. However, to maximize the performance gain of D2D communication, there are many open challenges that need to be addressed. One of the main factors that influence the performance of D2D communication in cellular heterogeneous networks (HetNets) is interference management. Transmission mode selection, resource allocation, power control and small cell deployment strategies are key factors that contribute to interference for D2D communication in cellular HetNets. In this thesis, an empirical investigation of the key factors influencing interference for D2D communication in cellular HetNets is described and its results are reported. In the investigation, the key performance-limiting factors are identified and measured by simulation as well as analytically. A new mode selection technique for improving D2D performance in HetNets is reported. The effect of various key performance-limiting factors, including DUEs positions and Signal-to-interference plus noise ratio (SINR) are analysed. Transmission mode is selected based on D2D user equipment (DUE), cellular user equipment (CUE) and evolved Node-B (eNB) locations and their mutual distances. The proposed mode selection scheme provides better outage probability and sum rate for D2D communication. Another main contribution of this thesis is the development of a new dynamic algorithm for interference management in D2D-enabled cellular HetNets. Various parameters for defining mutual interference within the 3-tier cellular network are defined and their effects on system performance are investigated. Achieved small cell density, transmission power control and device locations help to manage interference leading to higher outage probability and system throughput. A machine learning (ML)-based power control and resource allocation for interference management in a D2D-enabled cellular network is found to have a significant effect on achieving higher throughput and better quality of service (QoS). A deep Q-network (DQN) based deep reinforcement learning (DRL) algorithm is proposed to optimize resource allocation where D2D acts as an agent and take decision independently based on learned optimal policy from the environment. D2D-enabled cellular network design and deployment strategies are outlined and recommendations are made for various system design scenarios.
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