Doctoral Theses

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Synthetic Studies Towards the Spirocyclic Imine Moiety of Cyclic Imine Marine Toxins
(ResearchSpace@Auckland, 2024-07-31) Ma, Chao; Brimble, Margaret; Li, Freda
Dinoflagellate-produced marine toxins, a class of cyclic imines, form the core of various pharmaceutically relevant natural products featuring a spirocyclic imine motif. These toxins are classified into three subgroups based on their imine ring sizes: 5,6-spirocyclic imines (e.g., portimine A (7a)), 6,6-spirocyclic imines (e.g., kabirimine (6)), and 7,6-spirocyclic imines (e.g., pinnatoxin G (2g)). The spirocyclic imine moiety is the key pharmacophore driving their diverse bioactivities, and synthesising this moiety is crucial for structure-activity relationship studies and the eventual total synthesis of these natural products. This study provides a convergent exo-selective Diels-Alder approach to access various spirolactams bearing the desired anti relative stereochemistry present in the cyclic imine marine toxins. It was revealed that the reactivity and diastereoselectivity of the Diels-Alder cycloadditions were significantly influenced by the protecting groups incorporated on the dienophile/diene (P and R), the ring size of the α-exo-methylene lactam dienophiles (n = 0-2), the side chain length of the substituent on dienes (m = 1-3), and the types of dienes (X). The 6,6-spirocyclic core 428 of kabirimine (6) was prepared from the Diels-Alder cycloaddition between α-exo-methylene lactam 139h and silyloxydiene 410d followed by the regioselective vinyl group installation. Alternatively, a tandem Diels-Alder/Stille coupling reaction sequence was employed, requiring the use of bromodiene 91g to effect a Diels-Alder cycloaddition with α-exo-methylene lactam 139g. The use of chiral methyl α-exo-methylene lactams 139h and 139g in Diels-Alder cycloadditions proceeded with a complete diastereocontrol to afford (6S,7R)-spirolactams 352a and 342a as the only isomer albeit bearing the opposite stereochemistry to kabirimine (6). This study established a robust platform for constructing the spirocyclic core of portimine A (7a) and kabirimine (6), paving the way for stereoselective synthesis of the more functionalised spirocyclic core of other cyclic imine natural products (e.g. pinnatoxin G (2g)).
Objects Detection and Tracking Using mmWave Technologies
(ResearchSpace@Auckland, 2025-04-01) Huang, Xu; Nitish, Patel; Wang, Kevin I-Kai
Smart sensing systems have been a significant focus in the industrial community. With the integration of intelligent sensors, controlling buildings and factories autonomously has become both economical and straightforward. However, the central concern in this field remains to identify effective detecting and tracking mechanisms to make real-time decisions and overcome environmental challenges. Therefore, millimeter-wave radar technology (mmWave) has garnered enormous attention from researchers worldwide. The design of efficient object detection, tracking and classification models based on mmWave technology emerges as a possible solution to the challenges of smart sensing systems. This study presents several strategies for detecting, tracking, and classifying multi-objects. These methodologies have been developed to overcome some significant obstacles in smart sensing systems, including accuracy and computing constraints. In the first phase of this research, we developed a small and fast object detection and tracking system for indoor applications. The system operates on an embedded platform in real time with high accuracy. One of the most common challenges of sensing technology is ensuring portability and scalability due to computing constraints. To overcome this challenge, we propose a system with two efficient clustering algorithms for rapid processing and high accuracy. The Recursive Kalman Filter (RKF) tracking algorithm also helps reduce algorithmic complexity and computation time. We evaluated the proposed method through several real indoor scenarios based on a Raspberry Pi platform, demonstrating its effectiveness. The subsequent phase of this research proposes a multisensor-based fusion system for indoor object detection and tracking. The system employs two noise reduction stages to distinguish cluster groups and remove noise effectively. The proposed data fusion method effectively estimates the transformation of the data alignment, synchronizes the results, and visualizes object information acquired using one radar on another. The tracking algorithm with data association accurately tracks multiple objects simultaneously. We demonstrated the proposed system's effectiveness and advantages over commonly used methods in scenarios involving occlusions and weak data due to sensors returning weak signals or being lost from the sensor's view by low signal reflections. This fusion system consisting of dual sensors has the potential to improve tracking accuracy significantly. In the final phase of our research, we proposed an identification and classification system that utilizes mmWave radar and deep learning. The point cloud data undergoes processing using a refined density-based clustering algorithm to accurately extract ground truth in 3D space. We used a bi-directional long short-term memory (BiLSTM) network trained with center loss added to the softmax loss to recognize the identities of objects and address the scattered features issue. A Random Forest layer predicted a binary output identifying intruders or insiders. We evaluated our proposed system through a comparative experiment against existing architectures in the literature. We extended the sensing technology into a dynamic platform and examined the potential of mmWave radar sensors in robotic navigation for indoor object avoidance and navigation purposes due to the increasing demand for such services. The performance of the proposed strategies was evaluated and tested within practical operating limits throughout the thesis. Although the proposed object detection and tracking mechanisms offer a promising alternative to the currently established methods, there is still potential for improvement in future work concerning theory and application.
The Involuntary Swindler: Readdressing the Impostor Phenomenon
(ResearchSpace@Auckland, 2025-03-29) Barker, Tessa; Peterson, Elizabeth
In the 1970s, the impostor phenomenon (IP) was coined to describe a self-perpetuating, internal experience of feeling like an intellectual phony, which was reported primarily amongst a select population of white, middle- to upper-class high-achieving women (Clance & Imes, 1978). Since its introduction, the IP has gained significant traction in academic and lay communities, leading to various interpretations of what it actually is within the literature. Recently, concerns have been raised by scholars and laypersons alike regarding the conceptualisation and utility of the IP, alongside a noticeable gap in research addressing these concerns. Accordingly, this thesis aims to contribute to the advancement of IP theory by exploring the conceptualisation of the IP within and across academic and lay domains. To accomplish this, I conducted two primary studies as part of an exploratory mixed-methods research design. The first explores the understanding of the IP within the academic domain, and the second in the lay domain. This thesis then compares and integrates the findings from both studies and, in valuing both domains, considers what may be needed to move the research field forward. The research shows that academic and lay circles discuss conceptual factors and framing variables related to the IP in different ways. This variation likely contributes to the increasing ambiguity of the IP concept and the expansion of its conceptual boundaries. In addressing this issue, this thesis offers a contemporary conceptual framework that clearly distinguishes the core concepts of the IP from framing variables. This effort aims to refine the concept and help future researchers develop a comprehensive understanding of the topic that resonates with both scholarly and general audiences. It is hoped that this shift could aid in identifying individuals most affected by the IP and inform interventions through more targeted approaches.
Synthetic Applications of The Chitin-Derived Platforms Dihydroxyethyl Acetamidofuran (Di-HAF) and 3-Acetamido-5-Furfuryl Aldehyde (3A5F)
(ResearchSpace@Auckland, 2024-08) Neville, Jessica Christina; Sperry, Jonathan; Leitao, Erin
Chitin (79) is the second most abundant biopolymer on earth and a reservoir of biologically fixed nitrogen. Chitin (79) is one of the main components (20 – 30%) of crustacean shells. With an estimated six to eight million tonnes of crustacean shell waste produced yearly, converting chitin (79) into value-added compounds is desirable. As Di-HAF (101) and 3A5F (103) are easily synthesised from the monomer of chitin (79), ¬N¬-acetylglucosamine (80), these N-containing bio-based platforms could be used to synthesise an abundance of N-compounds in procedures independent of the Haber process. To begin, we demonstrated the first use of Di-HAF (101) as a chiral pool synthon in synthesising epi-leptosphaerin (266). Silylation of Di-HAF (101) gave TBDMS Di-HAF (308), which, upon photooxygenation, produced 3-acetamido-5-methoxy butenolide 309. A one-pot selective C5 reductive deoxygenation and desilylation then furnished epi-leptosphaerin (266) as a single diastereomer. Di-HAF (101) was silylated at the primary alcohol to give TBDMS Di-HAF (391) and then subjected to an Achmatowicz rearrangement to afford pyranone 393, retaining the biomass-derived stereocentre. From here, several Haber-independent 2-aminosugars and related pyranones were accessible. Additional reactions of Di-HAF (101) were investigated. A Paternò–Büchi cycloaddition of Di-HAF (101) did not give the desired dioxabicyclo[3.2.0]heptene 431a/b or 432a/b. Instead, a photoinitiated Achmatowicz rearrangement occurred, giving pyranone 390. Unexpectedly, an oxa-Pictet-Spengler reaction of Di-HAF (101) afforded difurylmethylpropane 500 rather than the anticipated furo[3,2-c]pyran 499. Finally, hydrogenation of Di-HAF (101) at atmospheric pressure gave 2,4-disubstituted tetrahydrofuran 433a/b (dr 1:1). Increasing the pressure improved the diastereomeric ratio to 1:0.5. Some investigations on the applications of 3A5F (103) towards the bio-based synthesis of penidilamine (512) were conducted. Reductive deoxygenation of 3A5F (103) gave 5-methylfuran 513. Photooxidation to 3-acetamido-5-methoxy-5-methylbutenolide 514, followed by selective C5 reductive deoxygenation, furnished 3-acetyl-5-methylbutenolide 515. Subsequent attempts at deacetylation were unsuccessful, thus, we were unable to complete the synthesis of penidilamine (512). 3A5F (103) was also used as a platform in a proposed synthesis of fritenolides D (532) and E (533). A modified Julia olefination with 2-(tridecylsulfonyl)benzo[d]thiazole (546) produced unstable vinyl furan 547. The reduction of vinyl furan 547 to 535 was unsuccessful, with only degradation occurring. Additional attempts at C-C bond formation using alternate methods were fruitless. However, when a Stetter reaction was attempted, instead of the desired 1,4-dicarbonyl 565, furfuryl ethyl ester 566 formed unexpectedly. The scope of this oxidative esterification was explored, and Haber-independent 4-amido-2-carboxylates were prepared.
Local scour mechanism around monopile foundations subjected to cyclic lateral vibration
(ResearchSpace@Auckland, 2025) Yao, Zishun; Melville, Bruce W; Shamseldin, Asaad Y; Guan, Dawei
Offshore wind turbines usually experience large numbers of lateral cyclic vibrations induced by winds and waves in their service life. The local scour process and vibrations will likely occur simultaneously in the field, threatening the stability of the monopile foundation of Offshore Wind Turbines (OWTs). However, traditional studies mainly focus on local scour around static monopile foundations. The local scour mechanism around monopile foundations subjected to cyclic lateral vibration remains unclear. To address this research gap, the study reported herein was undertaken. The study is an experimental investigation of motions of sand particles around vibrating monopile foundations and subsequent examination of the local scour mechanism under different hydrodynamic conditions. Firstly, a sandbox experimental system was developed to analyse the characteristics of sand motion under cyclic lateral vibration, considering factors such as backfilling sand and saturated conditions. Subsequent experiments focused on the local scour process under current-only and combined wave-current conditions. In current-only conditions, the local scour development characteristics and equilibrium scour depth in different flow intensities are analysed. Additionally, the influence of vibration direction on the local scour is investigated. Lastly, the local scour mechanism around monopile foundations subjected to cyclic lateral vibration under combined wave-current conditions is investigated. The coupling effects of vibration, waves, and currents on local scour process and equilibrium scour depth around the foundation are studied. To quantify the hydrodynamic intensity induced by waves and currents, considering the influence of sediment grain size, a new dimensionless parameter named the undisturbed friction velocity-based Froude number (Fr*) is proposed. Furthermore, equations for predicting equilibrium scour depth around vibrating monopile foundations under current-only and combined wave-current conditions are proposed. In summary, this thesis represents a pioneering effort to systematically investigate the interaction between piles and soil, as well as the local scour mechanism around monopile foundations subjected to cyclic lateral vibration under complex environmental conditions. The findings significantly enhance our understanding of the local scour issues surrounding monopile foundations for OWTs and hold promise for improving foundation design and enhancing scour protection measures in offshore engineering practices.
‘Talk about constitutional government in New Zealand’: New Zealand’s Constitution in Hansard, 1854-2020
(ResearchSpace@Auckland, 2025-03-26) Woodman, V. K. G.; Curtin, Jennifer; Kemp, Geoff
New Zealand (NZ) is a constitutional iconoclast. It is one of three states without a single, written constitution, has no supreme law, and is an unitary, unicameral system in which parliamentary sovereignty is a central constitutional principle. Because NZ’s whole constitution could perhaps be changed by simple parliamentary majority, this thesis describes the history of constitutional thought, as expressed by NZ’s MPs in the 536,079,187 words of Hansard compiled between 1854 and 2020. I ask three questions of the debates: what is NZ’s constitution? What is and is not constitutional, and what sort of actions and institutional arrangements does this entail? Have these understandings changed over time, and how? To answer these questions, I created an archival “soak and poke” method using computational assistance to locate and quantitatively describe Hansard data, and to select tracts of material for qualitative, historical analysis. I find that MPs largely understand NZ’s constitution as flexible and unwritten, and favour only gradual, evolutionary changes. What they regard as constitutional or not depends on both prevailing—and often inherited British—beliefs about a proposal, and the process used to pursue it. There is a long history of debate constitutionalism that prioritises collective self-restraint, obtaining parliamentary supermajorities, consensual legislative strategies, and non-binding electoral or plebiscitary approval for constitutional change proposals. In addition, MPs prefer a form of parliamentary sovereignty that I term “House sovereignty”, i.e. that the ultimate power should rest with elected representatives. There have been challenges posed to House sovereignty by Governors, Legislative and Provincial Councillors, the judiciary, the Treaty of Waitangi, legal rights protections, and popular sovereignty measures. Yet most MPs will not tolerate any counterfoils to House sovereignty that are not of their own making, or which could unequivocally bind their future actions. The House historically justified this because of its popular basis, and MPs continue to insist that they should be the guardians of NZ’s constitution. Though many acknowledge the danger of this position, most nonetheless believe it best for politicians to decide what is constitutional, and that concentrated constitutional power is the best guarantee of responsive government, and protection for citizens.
Afar in the Desert: Mapping an Identity for South Africa’s 1820 Settler Descendants
(ResearchSpace@Auckland, 2024) Young, Christopher Michael; Hipkins, Gavin; Crowley, Lisa
The area known as the Eastern Cape of South Africa holds constant reminders of the destruction wrought by colonisation. Is it possible to map the experience of the descendants of the 1820 British settlers in South Africa, while still acknowledging the irreparable damage done to the Indigenous way of life by their ancestors? By charting the experience of the community that identifies itself as 1820 settler descendants through an investigation into personal stories, artefacts and landscape, this research attempts to recognise the contradictions that lie at the heart of this community; uncovering what it might mean to be an 1820 settler descendant in contemporary South African culture and the globalised diaspora. Specifically, it explores whether there is a role for contemporary art to actively consider the interplay between history and responsibility, race and reconciliation; creating a space between public resistance and personal healing. The British critical theorist Annie Coombes describes reparation as a generational process, recognising that there remains much for white South Africans to apologise for. However, because South Africa’s Truth and Reconciliation Commission (TRC) was focused more on the dissolution of apartheid and less on the acts of colonialism that preceded it, the settler descendants still struggle to understand how to make reparations for actions that took place over 200 years ago. The pain of transformation is palpable within their community; producing “glimpses of a past that no longer seems to be ‘ours.’’ While for many years the stories and histories of South Africa’s Indigenous people were suppressed, contorted, hidden and manipulated for the purposes of maintaining colonial dominance, now the settler experience is seen as no longer relevant, creating a sense of invisibility and social decline amongst the ever-dwindling descendant community, reflected in the government’s policy of land reform. They are facing a struggle to retain and record their personal history, and to find relevance and meaning in a rapidly changing society. The question of how settler descendants reconcile their past and present – and more importantly, how they can be given permission to do so, despite historical atrocities – is central to this thesis. As a first generation South African born to British parents, who immigrated in 1968, my identity has been partly formed by the British influence. However, I also have a half-sister who is Khoisan (the first people of the land) and is now based in England. As such, I am keenly aware of the cycles of colonisation and the way this impacts generations. For this reason, my research considers three main areas: the intersection between memory, history and self from a postcolonial and decolonial perspective; the connection between photography and identity; and the way in which landscape can become a means for artists to portray the connection between the external and the internal, the past and the present. Using this framework, I have created artworks that utilise photography and video to explore the layers of experience, memory and trauma that exist within the 1820 descendant communities in South Africa and New Zealand. My works explore how image-making can indeed become a means of sense-making; of recognising feelings of loss but also making necessary reparations. Photography, which is inextricably bound up with memory, is an ideal way to help facilitate this process. In the words of British cultural historian Annette Kuhn, “The language of memory does seem to be above all a language of images… acts of remembering often bring forth thoughts and feelings that seem hard to explain in any rational way.” This research aims to recognize and inscribe the stories of the settlers and their descendants, however controversial; to reflect both the struggles and traumas of the past and reveal some hope for the future.
Understanding unmet need and addressing access to eye health services in Aotearoa New Zealand
(ResearchSpace@Auckland, 2025-03-25) Rogers, Jaymie Tingkham; Ramke, Jacqueline; Harwood, Matire; Kandel, Himal; Black, Joanna
Background The leading causes of vision impairment have effective interventions, but differential access to eye health services mean some population groups experience worse eye health. Inequity in eye health has historically received little attention in New Zealand. Aim The overarching aim was to assess vision impairment and access to eye health services in New Zealand. Methods Four complementary mixed-methods studies were undertaken. First, a systematic scoping review summarised the extent of evidence on vision impairment and access to eye health services in New Zealand. The remaining studies were within a project that provided cost-subsidised eye examinations and treatment to adults from an underserved community. The second study explored eye health and previous eye health service use of this cohort. The third evaluated the impact of spectacle correction on vision related quality of life at three and 12-months after spectacle correction. Lastly, a qualitative study explored barriers and facilitators of accessing eye care. Results The scoping review highlighted that most evidence on access to eye health services in New Zealand focused on cataract or diabetic retinopathy, with Māori and Pacific people consistently underserved; few studies focused on uncorrected refractive error. A total of 242 adults (63% female, median age 64 years) participated in the community-based study (60% Pacific people, 25% Māori), most of whom had distance or near vision impairment and half of whom (53%) reported never previously accessing optometry care. Most vision impairment was caused by uncorrected refractive error (85%), yet three-quarters of participants reported never having had custom-made spectacles (73%). Among the 207 people dispensed spectacles, quality of life was significantly higher at three-months, and this was maintained at 12-months. Cost was a major barrier to accessing eye care, while patient-provider communication was an important facilitator. Conclusion Ethnic disparity in access to eye care is evident in New Zealand. This research uncovered considerable unmet need for refractive error correction in an underserved community, largely due to prohibitive cost of seeking care, while correcting this refractive error significantly improved quality of life. Equity-focused strategies are required to achieve universal health coverage for eye health, including financial protection for those unable to access eye care.
Lanthanum Carbonate-Based Adsorbents for Low-Level Phosphate Treatment
(ResearchSpace@Auckland, 2024-07) Li, Jing; Yu, Wei; Young, Brent; Li, Bing
Phosphorus (P) pollution is a widespread environmental concern worldwide. Excessive phosphate discharge can trigger eutrophication, negatively affecting the aquatic ecosystems, economic development and human health. The low threshold of 0.02 mg P/L for inducing eutrophication in water bodies challenges conventional technologies to effectively remove phosphate. Adsorption technology is widely recognized for its high capacity for low-level phosphate removal. However, the reduced adsorption capacity of adsorbents at low phosphate concentrations results in high costs, posing an impediment to the control of eutrophication. This project aims to develop lanthanum (La) carbonate-based adsorbents suitable for low-level phosphate removal. Indeed, La carbonate exhibited an excellent adsorption capacity at low phosphate concentrations. Exploration of the adsorption mechanism revealed the importance of the ion exchange capacity of the adsorbent for low-level phosphate removal. To further enhance the adsorption capacity and reduce costs, the Fe modification strategy was proposed. It was demonstrated that the conversion of Fe(II) to Fe(III) during the synthesis process could transfer electrons to the adjacent La active site, which optimized its electronic structure and enhanced electron transfer between phosphate and La, thereby facilitating phosphate adsorption. Additionally, Fe modification also enhanced the adsorbent's resistance to dissolved organic matter in real water due to the weaker coordination ability of Fe than La. Further, magnetic La/Fe carbonate was prepared using inexpensive magnetite as the carrier and Fe source, exhibiting the high adsorption capacity, excellent separability and low cost. The study also demonstrated that metal ligands species and amount and surface-active metal sites coverage caused a decrease in adsorption capacity of La-based adsorbents. The study clarifies the primary mechanism involved in La carbonate-based adsorbents-bound phosphate at low levels, reveals the advantages of the Fe modification strategy for phosphate removal, and provides a possible way to develop adsorbents for low-level phosphate removal.
Investigating the Role of Distinct α-synuclein Strains in Different α-synucleinopathies
(ResearchSpace@Auckland, 2024-11-11) Wiseman, James Alexander; Curtis, Maurice; Dieriks, Birger Victor; Murray, Helen
α-synuclein (α-Syn) is a structurally complex protein that is central to the pathogenesis of Parkinson’s disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA), which are collectively known as α-synucleinopathies. How the pathogenic misfolding of this single protein precipitates three pathologically and clinically distinct disease phenotypes remains enigmatic. The prevailing hypothesis posits that α-Syn is capable of adopting a multitude of unique 3D conformations, which are known as strains. These distinct strains are thought to drive the disease-specific misfolding and propagation of α-Syn in different α-synucleinopathies, giving rise to their heterogeneity. This thesis sought to comprehensively interrogate the differential biochemical properties of patient-derived α-Syn from the human brain affected with PD and MSA. Multiplex immunohistochemistry with epitope-specific α-Syn antibodies revealed that α-Syn aggregate structures in pathologically burdened regions of the human brain with PD and MSA look dramatically different and exhibit distinct cell type-specific and subcellular arrangements. N-terminus immunolabelling identified novel populations of perinuclear, microglial, astrocytic, and neuronal lysosomal α-Syn aggregates in the human brain with PD, that are not detected by other canonical α-Syn antibodies. Multiplex immunolabelling revealed that antibodies targeting α-Syn phosphorylated at the serine 129 residue significantly underestimate the actual α-Syn pathology load across α-synucleinopathies. Biochemical analysis of α-Syn with proteinase K demonstrated that N-terminus immunoreactive inclusion structures in PD, and oligodendroglial inclusions in MSA, are more susceptible to proteolysis compared to mature PD Lewy pathology and MSA neuronal inclusions, respectively. High-resolution confocal microscopy was utilised to study the intracellular and intranuclear architecture of oligodendroglial and neuronal α-Syn inclusions in MSA and characterise their pathological maturation. Finally, seed amplification assays were used to demonstrate distinct aggregation kinetics in neuropathologically confirmed PD and MSA cases, affirming the ability of these assays to reliably discriminate between α-synucleinopathies. In addition, these data demonstrate the enhanced seeding potential of MSA patient-derived α-Syn compared to PD α-Syn. The multifaceted investigation of α-Syn in this thesis highlights that the pathological misfolding and propagation of this protein in PD and MSA is disease-specific. It subsequently demonstrates that disease-specific α-Syn species represent distinct conformational strains. Collectively, this thesis sets the stage for more refined diagnostic techniques and, with further ultrastructural analysis of these unique α-Syn strains, provides a platform for more targeted therapeutic strategies for treating α-synucleinopathies.
RISC-V System-on-Chip in Practice: Investigating its Innovation and Customisation across various Application Scenarios
(ResearchSpace@Auckland, 2024) Zhong, Xinchao; Ma, Sean; Sham, Bruce
This thesis explores the implementation and versatility of RISC-V architecture across a range of specialized applications, demonstrating its significant potential in industrial measurement, automotive control, wireless communication, and digital signal processing. The research introduces five distinct applications of RISC-V technology, each within a different domain, showcasing the architecture's adaptability and efficiency. To the best of our knowledge, this is the first research on RISC-V's applications in respective fields. In Chapter 3, a pico-second timing System-on-Chip is developed for magnetostrictive displacement sensors, utilizing 180 nm CMOS technology to achieve a time resolution of 156 ps. Chapter 4 details the design of a RISC-V-based system-on-chip for motorcycle engine control units, incorporating advanced sensor interfaces to improve engine performance and reduce system costs. Chapter 5 discusses the application of RISC-V in mobile payment systems using visible light communication, enhancing transaction security and data processing capabilities. Furthermore, the chapter presents a system-on-chip for electronic toll collection that integrates multiple communication technologies. Chapter 6 introduces a high-precision PWM DAC design as a peripheral to RISC-V, achieving notable resolution improvements for industrial sensors. Finally, Chapter 7 examines the integration of RISC-V into joint source-channel coding systems, employing advanced error-correction and machine learning algorithms to enhance communication reliability and efficiency. The findings underscore RISC-V’s customization and flexibility, proving its suitability for diverse applications that demand high precision, security, and cost-efficiency. This thesis not only expands the academic understanding of RISC-V technology but also sets the stage for its future exploration and integration into emerging technological fields.
Online Feminist Collective Action: A Linguistic Analysis of Stance in the Egyptian Twittersphere
(ResearchSpace@Auckland, 2025) AbdelBaky, Engy Farouk; Buckingham, Luoisa; Showden, Carisa
This dissertation examined how 18 Egyptian feminist activists affiliated with the Egyptian Twittersphere navigated their stance towards women-related issues. It also explored the nature of their communities and the nature of their activism. The study employs a purpose-built dataset compiled using Python scripts to scrape all the tweets available from a selected group of Egyptian feminist Twitter accounts between 2009 and 2020. The study identified the themes they addressed in their Twitter accounts and how the activists negotiate their individualist, relational, and collectivist feminist voices when engaging with these topics. Data were manually coded and thematically analysed using Triandis’ (1998) Individualist/ collective framework and then linguistically analysed to identify stance linguistic devices using Hyland’s (2005) stance model. The study also drew on Downing and Roush’s (1985) analytical approach to feminist identity development. Together these frameworks enabled insight into how these accounts reported the lived (and memorised) experiences of Egyptian feminists in this timespan. Findings showed that these Egyptian feminists discussed multiple aspects of their identities as Egyptian feminists in the Twittersphere, including issues around activism, women, and the use of hashtags, to report and combat sexual harassment while expressing their Egyptian feminist identities. These feminists mainly focused on collectivist themes and oriented their feminist identity development towards “active commitment” (Moradi et al., 2002). The most frequently used linguistic stance device was singular self-mentions, which testifies to the individualist aspect of their feminist identity. The coexistence between the collectivist and the individualist shows complex understandings of their identities as Egyptian feminists. Their second highest stance device is neutral “attitude markers, " highlighting a subtle need for validation and approval. Egyptian identification was an important factor that influenced how the feminist activists related to different themes, attitudes, and potential actions.
Older Chinese Migrants in Auckland City: Language, Coping Strategies, and Well-Being
(ResearchSpace@Auckland, 2025) Chen, Yingqiu (Mac) ; Buckingham, Louisa ; Wang, Danping
This study examines the language challenges, life routines and well-being of older Chinese migrants in Auckland, New Zealand. The study has three objectives: (1) to explore the specific language challenges participants encounter in their daily lives; (2) to identify the impact of these language challenges on their overall well-being (physical, psychological, and social well-being); (3) to uncover the coping strategies they employ to cope with the language challenges and support their well-being. The qualitative study design draws on data compiled over a period of six months from 18 older Chinese immigrants living in Auckland. The research instruments encompassed a combination of a questionnaire, two rounds of interviews, and three rounds of go-alongs. The data were analysed using a hybrid approach of thematic analysis and content analysis facilitated by NVivo 12. The study identified three domains in which the older migrants encountered language challenges: interpersonal communication, instructive activities of daily living (hereafter IADL) for participants' ability to function in society (e.g., taking a walk, shopping, banking), and civic engagement (e.g., political elections). I established that language challenges within IADLs exhibited a stratification of complexities related to the venues' specificities and tasks involved. Language challenges were found to have negative effects on participants' physical (e.g., the considerable stamina needed for routine matters such as taking a bus), psychological (e.g., embarrassment, emotional suppression, loneliness, social anxiety), and social (e.g., limited social interaction opportunities, social isolation) well-being. Finally, the study identified three aspects of coping strategies that participants developed to respond to these language challenges, namely problem-focused coping (e.g., taking English courses, using technology), emotion-focused coping (e.g., seeking support from family members, ethnic communities, institutions), and meaning-focused coping (embracing the mindset of “let-it-be” and “no-difference”). The employment of these strategies sustain participants' overall well-being. The study concludes with theoretical, methodological, and practical implications.
Automatic Detection and Quantification of Chemicals of Interest Utilizing Deep Learning Algorithms in Electrochemical Biosensors
(ResearchSpace@Auckland, 2024-03-12) Esmaeili, Fatemeh; Wang, Alan; Plank, Natalie; Unsworth, Charles
Nanomaterial-based aptasensors are crucial for detecting small biological entities. Effective signal processing methods are essential for improving biosensor performance by enhancing the identification and quantification of target analytes. This thesis investigates signals from three electrochemical aptamer-based sensors, each featuring distinct receptors, analytes, and signal lengths. The ultimate objective of this study is the automated detection and quantification of target analytes within the sensor-recorded signals, resembling a classification task. In order to achieve this objective, the thesis explores evolutionary pathways. The initial classification task involves identifying and quantifying specific analyte concentrations across six distinct classes, ranging from zero presence to 10 µM. Subsequently, a second classification task was designed to differentiate abnormal from normal data segments, detecting the presence or absence of analytes in the sample. When detected, this task further aims to identify the specific analyte and quantify its concentration. Data scarcity presented a significant challenge, necessitating the use of data augmentation techniques. An initial approach involved scaling data augmentation to address limited original data availability. Long short-term memory (LSTM) networks were utilized for analyte concentration prediction, with systematic variations for fine-tuning in network configuration and data augmentation quantity showing notable impact on model performance. Consequently, building upon the findings from the previous step, an automatic anomaly detection method, utilizing autoencoder-based prediction models, was introduced in a semi-supervised learning approach. Autoencoder networks and kernel density estimation (KDE) helped detect anomalies, although uncertainties persist regarding segment length's impact on model performance. In the concluding phase, a data augmentation technique using conditional variational autoencoders was introduced to address data scarcity within deep learning algorithms. Recurrent-based networks were developed for signal extrapolation to ensure consistent signal lengths, and short-term Fourier transform (STFT) preprocessing was explored. Seven deep learning classification models (GRU, unidirectional LSTM (ULSTM), bidirectional LSTM (BLSTM), ConvGRU, ConvULSTM, ConvBLSTM, and CNN) were developed, demonstrating the effectiveness of preprocessing methods in improving neural network performance for analyte identification and quantification. Overall, this study contributes to automated analyte detection and quantification using aptasensors, offering practical data augmentation methods, signal reconstruction, and insights into unknown datasets. The introduced classification model provides inspiration for novel methodologies.
Reaction Kinetics Studies on the Autoxidation of Bitumen
(ResearchSpace@Auckland, 2024) Herrington, Philip Raymond; Henning, Theunis FP
The oxidation of paving grade bitumens during handling, asphalt mix manufacture and subsequently over many years in the field in road surfacings, leads to hardening and eventual cracking and other forms of surfacing failure. Bitumen is essentially a very complex mixture of hydrocarbons, but there are features of the way in which bitumen oxidizes that are unexpected and don’t align with the conventional free radical chain mechanism of hydrocarbon oxidation- known as autoxidation. Basic information on the rate of oxidation and how this is affected by both the concentration of oxygen present and that of the reactive species in the bitumen, is lacking. Such information is needed to help begin to understand the reaction mechanism and find effective antioxidant compounds. The work presented in this thesis is one of the few studies in this area and the first detailed report of bitumen oxidation rate concentration dependencies over the whole reaction pathway (i.e. in both the fast and linear regions) and apparently the first to report reaction rate dependencies for the formation of hydroxyl and sulphoxide products. In contrast to most studies on the oxidation of bitumen, experiments were conducted at a realistic in-service road temperature of 50 °C, which necessitated very long reaction times but avoided potential artefacts and changes in the reaction mechanism that could occur at unrealistically high temperatures. Specific objectives of the work were: I. To develop and validate methodologies to enable measurement of the reaction rate of bitumen at different concentrations and with different oxygen concentrations. Measurements were made using bitumen solutions in two different solvents and thin solid films. The main assumptions/hypotheses underlying the experimental methods used to measure the bitumen and oxygen concentration rate dependencies were investigated and found to be valid: (a) The carbonyl group concentration is a good measure of the overall extent of reaction. (b) The carbonyl peak area measured by infrared spectroscopy is directly proportional to carbonyl group concentration (Beer’s law). (c) Under the conditions used oxygen diffusion into bitumen solutions and solid films was rapid and diffusion effects could be ignored. (d) Under the conditions used the solvents could be considered inert. (e) For oxygen, Henry’s law was found to apply to both bitumen solutions and solid films. II. To measure how the reaction rate depended on the available concentration of oxygen and bitumen reactive species. The results of the experiments showed that the overall bitumen oxidation rate (based on the carbonyl formation rate) depended on bitumen and oxygen concentrations [B] and [O2] to the power of 1.2 and 0.5 respectively. The formation of sulphoxide and hydroxyl groups (the other major reaction products) also showed oxygen dependence, and this was also approximately half order in oxygen concentration. III. To determine if the measured bitumen and oxygen concentration rate dependencies varied over the course of the reaction (i.e. in both fast and linear rate regions). Notably the dependency of the rate on reactant concentration remained the same in both the fast and linear regions of the reaction. IV: To compare the experimentally determined rate dependencies to those expected from bitumen oxidation mechanisms proposed in the literature. The findings were inconsistent with the currently “standard” reaction mechanism for bitumen autoxidation (the Dual-Sequential mechanism) and show that it is probably not an accurate model for bitumen oxidation. The rate dependency findings, together with the observed lack of an induction period and the evidence for the presence of natural radical inhibitors (confirming previous research), are also inconsistent with a conventional free radical chain mechanism and point to the primary oxygen uptake step being a complex non-radical chain process.
The food environment and student dietary behaviour determinants in an urban Chinese university: implication for healthy eating
(ResearchSpace@Auckland, 2024) Li, Xingbo; Roy, Rajshri; Braakhuis, Andrea; Wall, Clare
Unhealthy diets increase the risk of various metabolic issues, especially among university students. The food environment has been implicated in creating an obesogenic generation, but little evidence was found in a Chinese university context. In this thesis, we aimed to understand the environmental and personal determinants of dietary behaviour among Chinese university students. Our systematic review identified 11 studies on how the food environment impacted student dietary behaviours, but in Western university settings only. Taste, availability, price, and nutrition literacy substantially influenced students’ dietary behaviours. We used the Chinese Nutrition Environment Measurement Survey for Stores (C-NEMS-S), a validated tool, to audit the food service context, food availability, and healthier options in an urban Chinese university food environment. A total of 52 outlets were audited in three on-campus canteens and further categorized into eight subtypes. Total C-NEMS-S scores (P = 0.0024) and food availability scores for starchy tubers (P < 0.001), dry beans (P < 0.001), vegetables (P = 0.0225), and fruits (P < 0.001) were significantly different across food outlet subtypes. The digital ethnography study built on the food environment audit. It aimed to explore how environmental factors influenced and were perceived by Chinese university students. We collected 90 days’ video, audio, graphic, and textual data on every eating occasion from 10 participants at Hebei Medical University. Thematic analysis identified three major thematic categories: social and environmental, food-related, and intrapersonal determinants. Students’ dietary behaviours were substantially influenced by interpersonal factors and food accessibility both on campus and at home. Diet interventions might target modifiable determinants, including increased healthy food availability and nutrition knowledge and skills to promote diet autonomy. Developing a comprehensive, reliable, and valid food environment audit tool would thoroughly contextualize the food environment lived by Chinese university students. Controlled diet interventions, quantification of diet intake, and diet quality assessment are warranted to evaluate the effectiveness of interfering with modifiable determinants. Findings of this thesis could inform university and government policymakers on healthy eating guidelines for university students, provided that further research evidence is synthesized from diverse university settings in China.
Towards Improved Volcano Monitoring via Automatic Classification of Continuous Tremor
(ResearchSpace@Auckland, 2024) Steinke, Bastian; Jolly, Art; Cronin, Shane
Machine Learning provides new means to detect previously unknown patterns in volcano-seismic signals. Some of these patterns may be precursors to eruption, or change of volcanic activity state. This is particularly interesting for ‘wet’ volcanic systems such as Whakaari (White Island), which regularly produce steam-explosions that are difficult to predict. An unsupervised classifier based on Self-Organising Maps was trained on tremor data recorded at Whakaari to understand changes in seismicity throughout different phases of volcanic unrest. The prototype classifier distinguishes between quiescent and unrest signals, focussing the temporal resolution of periods of enhanced hazard. This provides insights into the mechanisms driving individual unrest episodes. The analysis also highlighted the presence of subtle seismic patterns, which were interpreted to reflect a magma intrusion event and subsequent growth of a lava dome. Visualisation of the periodic characteristics of the signal allowed earlier detection of this than most other current monitoring techniques. This discovery may benefit monitoring at other volcanoes where similar subtle, periodic signals are observed. In order to improve our understanding of the link between parameters that best describe continuous tremor and volcanic processes, their temporal evolution (‘feature dynamics’) are extracted from a high-resolution 100 Hz seismic signal. This was achieved via High Performance Computing. Different visualisation approaches highlight the numerical existence of pre-defined classes of tremor. Hypothesis and correlation testing helped to extract a small number of interpretable features that efficiently describe tremor classes. This is an improvement on classifiers that work with unknown parameters, or approaches using reduced seismic data as input. Automatic selection of tremor classes was coherent with volcanic regimes manually defined in the literature and also expands existing classification schemes for transient volcanic earthquakes. This study provides a promising start on a journey toward identifying and systematically categorising continuous tremor observed at volcanoes worldwide.
Node Classification on Graph Data with Global Learning
(ResearchSpace@Auckland, 2025) Zhu, Yonghua; Witbrock, Michael; Amor, Robert
Node classification is a core task in graph-based machine learning, where the goal is to predict labels or categories for nodes in a graph, leveraging the relational structure and attributes of the data. To enhance the expressiveness of node representations, various Graph Neural Networks (GNNs) have been proposed to aggregate information from neighbouring nodes, conducting message-passing within local receptive fields, a process also referred to as local learning. However, the suboptimal nature of the available graph structure, often characterized by noisy edges or missing edges, generally negatively affects the performance of node classification. To address this issue, this dissertation explores node classification by considering relations among all nodes, referred to as global learning, and further investigates opportunities and challenges for its application across different scenarios. -We introduce Chain of Propagation Prompting (CPP) to enhance the expressiveness of node representations while reducing the dependency on label information. CPP involves designing a simple message-passing pattern, which we incorporate into node representations using graph contrastive learning. This simple pattern prompts multi-head self-attention-based layers to globally capture more complex patterns while minimizing their reliance on label information. Additionally, we implement majority voting to enhance the predictive confidence of multiple heads. -We introduce Robust Node Classification under Graph and Label Noise (RNCGLN) to improve the robustness of node classification when both graph and label noise are present. By integrating local graph learning and global graph learning, RNCGLN can provide comprehensive information to enhance node classification performance. Additionally, we develop graph and label self-improvement modules to improve and supplement the quality of supervisory information. Consequently, RNCGLN leverages self-training and pseudo-label techniques to facilitate two self-improvement processes in an end-to-end learning framework. -We introduce a Flexible-pass Filter-based Graph Transformer (FFGT) to resist adversarial attacks on graph data. Leveraging self-attention's ability to capture arbitrary graph filters, our self-attention layers with three heads capture multi-frequency representations across low-frequency, hybrid-frequency, and high-frequency ranges. Additionally, we designed graph learning and fusion modules to improve self-attention effectiveness in capturing designed information, yielding a flexible-frequency representation. Consequently, FFGT shows consistent resistance to adversarial perturbation in multiple datasets and against diverse adversarial attacks. We conducted theoretical analyses and numerical evaluations of our proposed methods using diverse graph data. The experimental results show that our methods, leveraging global learning strategies, consistently outperform traditional Graph Neural Networks (GNNs) based on local learning. This superior performance is demonstrated across various scenarios, including diverse graph datasets, graph noise, label noise, and multiple adversarial attacks. Additionally, our theoretical analysis validates the effectiveness of each proposed method in addressing these challenges. Together, these findings confirm that our methods enhance expressiveness, improve robustness to noise, and strengthen resilience against adversarial attacks.
Cross-scale resilience for organisations: A study of three geographic regions
(ResearchSpace@Auckland, 2024) Bhardwaj, Varun; Wolfgramm, Rachel; Tisch, Daniel; Newth, Jamie
Cross-scale resilience requires organisations to move beyond a firm-level interpretation of resilience and embrace complex dynamics in social-ecological systems (Williams et al., 2021). A social-ecological system is a self-organising assembly of physical, biological and geographical elements moving through phases of an adaptive cycle (Gunderson & Holling, 2012). Cross-scale resilience is the ability of organisations to work in harmony with social-ecological systems. However, organisational literature on sustainability prioritises organisational resilience at the expense of social-ecological parameters. The literature is largely silent on how feedback effects across nested social-ecological systems shape organisations attempts to become more ecologically sustainable. Acknowledging that organisations’ attempts to achieve ecological sustainability are influenced by the geographical, biological and physical characteristics of their region and their position in global society, the research question explored the interactions between social-ecological systems and organisations implicating cross-scale resilience. Data collection involved semi-structured interviews. A total of 73 interviews were conducted with farmers involved in dairying and horticulture settings across 10 countries including India, New Zealand and Malawi among others. In order to identify both barriers to cross-scale resilience and farmers attempts across regions to become more ecologically sustainable, 42 interviews from three geographic regions were selected for thematic analysis. An analysis of the barriers identified revealed that focal-scale bias by those prioritising organisational outcomes hampers cross-scale resilience. An analysis of the attempts identified revealed that monitoring slow variables such as biodiversity and proactively enhancing functional redundancy and response diversity fosters cross-scale resilience. By combining focal-scale bias and attention to slow changes, two distinct organisational profiles were identified, ‘focal-’ and ‘cross-scale organising’. Six case studies were constructed illustrating cross-scale and focal-scale organising across three geographic regions.
Why do Outcomes of Critical Congenital Heart Disease in New Zealand Differ by Ethnicity?
(ResearchSpace@Auckland, 2025) Watkins, Simone Amy Jennifer; Bloomfield, Frank; Gentles, Tom; Percival, Teuila; Ward, Kim
Critical congenital heart disease (CCHD) are life-threatening inborn structural heart abnormalities. Indigenous Māori and Pacific CCHD survival is inferior to European infants in New Zealand (NZ). Knowledge of why ethnic disparity in CCHD survival occurs in NZ is sparse. Therefore, this research aims to understand the contributors of inequitable infant survival in CCHD by ethnic group to inform healthcare advances in NZ. A multi-ethnic, multisource grounded theory was applied, intertwining Indigenous (Kaupapa Māori), Pacific (Talanoa) and Western worldviews, underpinned by the dialectical pluralism philosophical paradigm. Three sources informed the grounded theory: 1. A scoping review and a systematic integrative literature review; 2. A national retrospective cohort study of CCHD cases (excluding terminations) over 14 years with survival and Cox regression analysis and 3. An interview study of CCHD parent and healthcare professional experiences, with transcripts assessed for key concepts. The theory of navigating the disjuncture of a narrowly responsive healthcare system is presented. The scoping and systematic review revealed a dearth of NZ knowledge and unequal CCHD mortality risk burdens by ethnic groups. The cohort analysis (n = 1,039) confirmed inequitable CCHD survival by ethnicity with multivariable analysis identifying independent drivers to explain this difference: specific cardiac diagnoses; lower birthweight; comfort care management, and higher levels of deprivation. The interview study (n = 57 interviews, n = 25 parents, n = 20 healthcare professionals) identified three categories: 1) Minoritised groups experience disparate healthcare quality; 2) healthcare systems are under-resourced to provide equitable support for the differential needs of grieving parents, and 3) healthcare systems could engage minoritised families more optimally in shared decision making. Professionals seem positioned to acknowledge and support equitable changes in healthcare. Results suggest inequities in CCHD infant survival by ethnic group in NZ are attributed to disparate upstream health determinants and healthcare systems mediating differential quality experiences. Updates in health equity policy and practice are recommended if parity in infant survival for all is to be achieved. Increasing the knowledge base into mechanisms underlying broader inequities and interventions to reduce disparities is warranted.

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