Science: Theses and Dissertations

Permanent URI for this collection

https://ir.canterbury.ac.nz/handle/10092/841

Browse

Now showing 1 - 20 of 4860

Open Access
A Potability Risk Model for Drinking Water Self-suppliers In the Waitaha Canterbury Region
(2023) Blake-Manson, Hugh
Access to potable water is a fundamental requirement for maintaining human health. An estimated 13% or 666,000 New Zealanders – classed as Drinking Water Self-suppliers (DWSS) are entirely responsible for their stand-alone drinking water supplies potability, with tacit oversight from national agencies. This research develops an innovative data-driven model to evaluate DWSS relative risk in terms of the drinking water hazards, source exposure and social vulnerability across the 45,300 km2, Waitaha Canterbury region of New Zealand. Over 23,000 individual DWSS sites were identiﬁed, supplying c. 62,400 domiciled people. Of these c. 18,000 reside in the higher vulnerability health related demographic cohorts. In this region, and as a result of geological processes, readily accessible groundwater and surface water is aligned along west-east braided freshwater systems. These natural water systems also support intensive land use practices particularly across 7,500 km2 of low relief ‘plains’ including intensive animal grazing, wastewater disposal and industrial development with DWSS interspersed between. Utilising publicly available data, the ﬁrst relative risk assessment at a 22km2 grid scale was completed, with the ability to also assess risk at each DWSS site. When considering DWSS, 4,016 or c. 17.4% (10,843) people may consume microbiological contaminants above the New Zealand Drinking Water Standards maximum acceptable value (MAV) and c. 12.1% above organic MAV. 154 DWSS or c. 0.7% are estimated to consume water above all four of the hazard group MAVs. There are limited DWSS “consumer facing” practical and cost eﬀective point of use (PoU) water quality monitoring solutions. A novel, DWSS centred time-quality-cost framework conﬁrmed that while there are adequate sensor systems available globally, microbiological based technologies still require greater than 8 hours for conﬁrmation of pathogen presence or absence. This is inadequate given ingestion can result in rapid onset of illness and long term negative health impacts such as organ injury. A treatment system with microbial and chemical barriers remains the most eﬀective current solution. There is value in undertaking targeted DWSS site inspections to conﬁrm source water quality and check the water system against sanitary guidelines. DWSS residents’ privacy and security should be prioritised as part of any inspection.
Open Access
Healthcare technology adoption: a social-organisational perspective
(2024) Watson, Jake Marshall
The medical technology industry, valued at almost a trillion dollars annually, holds significant societal and individual impacts, where advancements are crucial for improving healthcare outcomes. However, the adoption of new healthcare technologies has a success rate of only 30-60%, highlighting a substantial challenge. This is particularly important given the current strain on healthcare because of underfunding, overworking, and an ageing workforce. It is evident from previous research that sufficient healthcare technology plays a pivotal role in addressing this problem. Moreover, previous frameworks pay little attention to socio-organisational factors. Therefore, the current research aims to explore how socio-organisational factors impact healthcare technology adoption. A sequential mixed methods exploratory design constituted of two phases was employed. Firstly, archival data was thematically analysed to explore general barriers and enablers of healthcare technology adoption. Secondly, a quantitative survey was administered to healthcare professionals to which regression and t-test analyses were performed. Data was collected on organisational and social aspects of HCT adoption, including relevant relationships, communication, and innovation culture. Moreover, enablers such as patient outcomes, usability, co-design, and workload accommodations were assessed as well. Results from thematic analysis found seven themes, these were: relationships, the nature of clinical work, the psychology of clinicians, culture, communication, training, and technology characteristics. Qualitative analyses gleaned further insight, proving relationships as a key predictor of technology adoption success. Results also revealed differences in importance between hardware and software regarding communication and training. This thesis highlights the necessity of encompassing socio-organizational factors in HCT adoption studies. For practitioners it demonstrates the importance of considering relationships, co-design, and targeting effective communication and training at specific modalities of technology.
Open Access
The effect of dosage of citric acid on cough thresholds
(2024) Tan, Gladys Li Yue
Purpose: Citric acid cough reflex testing (CRT) has been used within the clinical swallowing examination to evaluate laryngeal sensation and infer silent aspiration risk. Cough thresholds are defined solely by the concentration of citric acid that evokes coughing. Coughing is evoked by reduction in pH levels in the laryngeal environment, which occurs with higher doses of the same citric acid concentrations, suggesting that the amount of citric acid might be important to factor into threshold definitions. Furthermore, citric acid doses vary across CRT protocols, depending on factors such as the nebuliser and dosimeter used, differences in number of discrete inhalations across protocols, individual variation in respiratory patterns during tidal breathing. This study investigates the effect of citric acid dosage on evoked cough response. Methods: 16 healthy participants (23-79 years, eight men) attended two sessions spaced exactly a week apart. Citric acid doses of 0.1 to 1.9mol/L were inhaled in 0.2mol/L increments via a mouthpiece attached to a jet nebuliser and dosimeter. Each concentration of acid was inhaled once for the protocol of one session and six times for the protocol of the other session for a six-fold dosage. Both protocols included an initial saline practice dose and four placebo doses at regular intervals. A three-minute break and mandatory sip of water were taken after each step of the protocols. Natural cough threshold (NCT) across two cough threshold definitions (i.e. first C2 and consistent C2) and UTC at these cough thresholds were measured. A paired t-test for first C2 and a permutation t-test for consistent C2 were used to compare results across both protocols. Results: Cough thresholds were higher in the one-inhalation than the six-inhalation protocol for first C2 (mean difference 0.36mol/L, 95% CI [0.09, 0.63], p = 0.01) and consistent C2 (mean difference 0.55mol/L, 95% CI [0.09, 1], p = 0.02). Participants also displayed other airway protection behaviours throughout both protocols e.g. swallows, throat clears, change of respiratory patterns. There was no difference in UTC rating at cough threshold for first C2 (p = 0.49) and consistent C2 (p = 0.24) across both protocols. Conclusion: Airway sensitivity was increased with more inhalations of the same concentrations of citric acid. This implies that dosage may influence cough response when aspects of respiration are not controlled. This highlights that current definitions of cough threshold are insufficient to accurately indicate airway sensitivity, signifying the need to include both parameters of concentration and dosage. Until then, comparison of results from CRT protocols that differ in citric acid dosage delivered needs to be made with caution.
Open Access
Turgor Regulation in Phytophthora Zoospores
(2024) Sergent, Madison
Oomycetes are significant pathogens responsible for causing various plant and animal diseases, including root rot, potato blight, and kauri dieback, which can lead to substantial biodiversity and economic losses. Their infection strategy includes the production of asexual zoospores, which can play a crucial role in their spread to neighbouring plants and animals. Recent research has highlighted turgor regulation, the ability to control internal hydrostatic pressure, in asexual encysted zoospores of the oomycete Achlya bisexualis. This mechanism potentially enables spores to withstand environmental stresses, thereby increasing their longevity and infectivity. The objective of this study is to investigate whether turgor regulation is also present in the encysted and swimming zoospores, and hyphae of another more destructive oomycete, Phytophthora nicotianae, which affects agricultural plants globally. The encysted zoospores, swimming zoospores and hyphae were osmotically shocked with sorbitol, sucrose and sodium chloride at varying concentrations ranging from 0.1 – 0.7 M and morphological changes were investigated using differential interference contrast (DIC) microscopy. Plasmolysis in encysted zoospores was observed post osmotic shock in osmoticum solutions of concentrations > 0.3 M. After initial plasmolysis the protoplast deplasmolysed, indicative of a recovery of turgor. The rate of de-plasmolysis was dependent on the solute concentration used to impart the osmotic shock, with higher concentrations taking longer. In most cases the protoplast volume had returned to that prior to the shock within 60 minutes. After turgor recovery the encysted zoospores were viable with more than 82.5% germinating to form germ tubes. Swimming zoospores, which do not contain a cell wall were able to resist hypo-osmotic shock, likely due to their water expulsion vacuoles. However, swimming zoospores burst upon hyper-osmotic shock, suggesting that there is no mechanism in the wall-less spores to decrease cellular osmotic potential, either through mechanisms involving metabolism or membrane transport. This suggests a key difference in the physiology of swimming wall-less spores and encysted spores. No plasmolysis of P. nicotianae hyphae was observed in hyphae after an osmotic shock, but rounding and widening of the hyphal tip was present. Forty-five minutes after osmotically shocking the hyphae they had returned to their normal morphology at the tips. A better understanding of turgor regulation in Phytophthora zoospores means that we may be better able to address their longevity and infectivity, potentially improving disease management, agricultural yields, and the conservation of native species.
Open Access
Costly commitment signals and their impact on employability.
(2023) Leckie, Jess
Employment is crucial for people with substance abuse disorders (SUDs) to support sobriety, yet the stigma against people with SUDs makes it challenging for them to secure employment. The present research sought to create opportunities for people with SUDs to help themselves, by focusing on a cost-effective intervention to improve employability. Consequently, the current research applied costly signal theory (CST). CST suggests that individuals can enhance credibility by engaging in actions that could incur significant costs, effectively signalling their commitment to a certain behaviour, in this instance sobriety. In study 1, 2 potential employees were detailed to participants (N = 196), one candidate used a costly signal, and the other did not. Participants were tasked with evaluating how problematic potential employees could be, as well as selecting one for employment. Results indicated that a costly signal had an influence on the perception of how problematic an employee would be, particularly when the candidate was presented first. Most importantly, participants employed candidates who used costly signals at a significantly higher rate. Study 2 attempted to investigate the practical implementation of costly signals of sobriety, however, was unable to recruit sufficient participants as the majority of interested participants were excluded due to having to disclose violent criminal convictions. Future research should consider the impact of disclosure timing and if costly signals could influence additional aspects of the lives of people with SUDs, such as in housing, education, and healthcare.
Open Access
Evaluating extreme precipitation within extra-tropical cyclones over the Southern Hemisphere.
(2024) McErlich, Cameron
Extreme precipitation has numerous impacts, such as flooding, damage to infrastructure, availability of food and water, and changes in insurance costs. Understanding the causes and behaviour of these extremes is important, as extreme precipitation is predicted to become both more intense and more frequent in the future. An atmospheric feature associated with extreme precipitation are extra-tropical cyclones. Cyclones are key components of the atmospheric general circulation due to their ability to transport large quantities of heat, moisture, and momentum. The baroclinic instability, which feeds cyclones, largely balances the planetary budgets of energy and moisture at mid-latitudes. In this thesis, precipitation extremes are examined within cyclones across the Southern Hemisphere, and the underlying processes driving extreme precipitation within cyclones are investigated. ERA5 reanalysis output is used in a mean sea level pressure cyclone tracking scheme to identify cyclone centres and tracks. A cyclone compositing framework is used to provide a cyclone-centred perspective by examining data within 2000 km of each identified cyclone centre. Before using ERA5 to determine extreme precipitation and its drivers, we assess its suitability for cyclone compositing and investigate an appropriate threshold for extreme precipitation. ERA5 is initially compared with the WindSat dataset to assess the representation of cyclones within ERA5. WindSat is not assimilated into ERA5 and provides an independent assessment of ERA5’s quality. Compared to WindSat, ERA5 shows comparable spatial structures but underestimates total column water vapour by up to 5% and cloud liquid water by up to 40%. ERA5 also underestimates precipitation in the warm sector by up to 15%, but overestimates precipitation in the cold sector by up to 60%. This potentially suggests that cloud parameterisations are biased within ERA5. Despite these biases ERA5 shows a strong correlation with WindSat across the cyclone lifecycle, indicating its suitability for use in further cyclone compositing analysis. ERA5 is also assessed globally to determine a threshold for extreme precipitation to use within the cyclone composites. This threshold is required to change spatially depending on the latitude/longitude of the cyclone, as an extreme in one region might not correspond to an extreme in another. By grouping precipitation based on how often it rains, we develop a new framework for assessing global precipitation. This framework finds a strong relationship identified between the frequency of wet days and the intensity distribution of precipitation on those days, even though it connects spatially disparate regions of the globe. This key result is also observed in a number of gauge, satellite and reanalysis precipitation datasets, and is not just a product of how precipitation is represented within ERA5. This reinforces the value of ERA5 in precipitation related studies. Next, we apply the wet-day frequency regions within the cyclone compositing framework to assess extreme precipitation. Precipitation intensity distributions are used to mask cyclone composites based on 90th and 98th percentile thresholds, which change depending on the wet-day frequency. This novel methodology provides a way of quantitatively assessing precipitation extremes within a cyclone compositing framework. When cyclones are in a phase of strengthening before peak intensity, extreme precipitation occurs more often. A higher proportion of precipitation is determined as extreme during this period. The spatial extent of extreme precipitation is also found to be constrained around the cyclone centre compared to non-extreme precipitation, though extreme precipitation still displays a good spatial correlation with non-extreme precipitation. Finally, we investigate the underlying processes causing extreme precipitation within cyclones and how they relate to both large-scale and convective precipitation. Overall, large-scale precipitation predominates and is most commonly found in the comma cloud region. Convective precipitation is weaker overall but more frequent in drier regions of the cyclone. During periods of extreme precipitation events, large-scale precipitation becomes even more dominant across the cyclone composite, but weakens as the cyclone decays. Vertical velocity strongly influences large-scale precipitation regardless of cyclone strength, though correlation weakens after peak intensity is reached. For extreme precipitation this correlation is more moderate and absent during the decay phase, suggesting that a further driver such as water vapour is also important for extreme large-scale precipitation. Convective available potential energy and integrated water vapour flux do not exhibit a spatial correlation with convective precipitation. However, a strong correlation between convective available potential energy and convective precipitation is observed during extreme precipitation. This potentially suggests CAPE is a necessary condition for extreme precipitation but is not capable of producing the rainfall on its own.
Open Access
How to make a mapmaker : a social and technical study of digital geography.
(2024) Garcia, David
The networked and digital production of geographical knowledge in contemporary times is dependent on the labour and participation of online volunteers who create and share global geographical projects like OpenStreetMap (OSM). This practice of free and open mapping – often framed as crowdsourcing – is due to the social and technical nature of mapping. OSM, together with other kinds of participatory mapping and Geographic Information Systems (GIS), is celebrated as the democratisation of Geography and the development of individuals – especially those in the Global South – into mapmaking citizens in a seemingly inevitable digital world. However, the critical and political aspects of the making of such digital geography are usually ignored due to the ongoing illusion of mapping as a neutral and objective practice. It is also due to a broader colonial culture of searching for new frontiers and new worlds, especially in the geographical disciplines, which usually regard OSM as neogeography. From a native perspective, this PhD thesis takes on the challenge of studying such coloniality of digital geography in terms of context, discourse, and subjects by investigating the situations, factors, and alternatives involving the production of free and open-source maps by volunteer communities like that of OSM and related groups, especially those dealing with crises. To dive into the topic, this research studied the mapmakers through critical autoethnography, supported by wayfinding and storywork, and found out that mapmakers live highly social and politicised lives online and offline; while being influenced by complex factors such as education, precarity, attention, and recreation; and reproducing a cartographic, geospatial, and surveillant culture. In other words, the author of this PhD thesis studied digital coloniality by becoming a mapmaker, hence the title of the work, “How to Make a Mapmaker”. This thesis, mostly written through creative nonfiction, claims that participatory mapping, now done more digitally, is historically and presently intertwined with colonial projects as a method of collecting intelligence from Native and Indigenous peoples, with limited opportunities for resistance. Decolonisation is ultimately about the return of stolen land, which is often not the focus of participatory mapping communities under Western hegemony. I observed that participatory mapping, by focusing on individualism and uncritically revealing geographical knowledge to the public and the Internet, are incommensurable with and may be detrimental to collective struggles for decolonisation in both the Third World like the Philippines and settler colonies such as the United States and New Zealand. Also, amid such recolonisation of places like the Pacific, I emphasised the importance of hope and stories, which are also maps.
Open Access
Barriers and supports to the use of research by human resources practitioners in New Zealand.
(2024) O'Sullivan, Z. M.
The research-practitioner gap has been long established within the field of organisational psychology and has implications for both the relevance of the field and the efficacy of Human Resources (HR). However, although there are many recommendations from researchers about how to address this gap, these recommendations are based on the perspectives of researchers, not HR practitioners. Research also suggests a difference in research utilisation across domains of HR practice, however, the reasons for this difference have not been explored. To address this gap in the literature, the present study interviewed 15 HR practitioners within New Zealand about their perspective on research, their use of research across domains, and the barriers and supporting factors to use of research. It utilised theoretical sampling and semi-structured qualitative interviews to identify these barriers and supports to research use. The findings of the study support previous research’s findings regarding the impact of academic language and restrictions on organisational resources, but also demonstrate the factors influencing practitioners’ relationship with research, factors motivating and prompting research use and how practitioners interact with research, and tensions present within participants. Based on these results a new typology for categorising practitioners is proposed, and recommendations for increasing HR practitioners’ utilisation of research are provided.
Open Access
Exploring employee green behaviours in Aotearoa New Zealand organisations : a qualitative comparative case study.
(2024) Steyn, Josie
Organisations globally are urged to embrace environmental sustainability responsibility in light of their potential positive impact on mitigating climate change. In Aotearoa New Zealand, the government’s introduction of environmental policies has prompted organisations to integrate such policies into their purpose, vision, mission, and activities. However, the success of these environmental sustainability efforts relies on individual employees attitudes and behaviours. The current study aims to explore the multi-level factors that influence the adoption of employee green behaviours within the context of Aotearoa New Zealand’s current climate and environmental policies, utilising the Abilities-Motivation-Opportunities Theory as a theoretical framework. Employing an exploratory, qualitative, comparative case-study approach, 12 semi-structured interviews were conducted across two case organisations. Reflexive thematic analysis revealed five factors that were common across organisational levels: Individualism, Alignment, Perceptions of Authenticity, Motivation, and Facilitation. This study contributes to the existing literature examining employee green behaviours, and provides direction for future research. Furthermore, it provides practical applications for organisations wishing to encourage their employees in adopting green behaviours to collectively achieve organisational green goals and enhance their environmental sustainability efforts.
Open Access
A comprehensive review of publications about kelp and fucoids from New Zealand and subsequent experiments on the early life stages of Hormosira banksii.
(2023) Edmunds, Nicolette Rene
Kelp (Laminariales) and fucoids (Fucales) are canopy-forming macroalgae that cover ca. 25% of the world’s coastlines, including many rocky coastlines throughout New Zealand. Marine forests, dominated by kelp and fucoids, are highly biodiverse and productive ecosystems that provide ecosystem functions, such as nutrient and carbon sequestration and habitat for marine species. However, seismic uplift, urbanization, warming, heatwaves, invasive species, eutrophication, coastal darkening, sedimentation, and elevated grazing pressure have reduced their vertical and horizontal distributions, globally and in New Zealand, motivating calls for protection and restoration. Kelp and fucoids have been studied in New Zealand since the 1930s but their research has not yet been systematically reviewed. Here I reviewed published kelp and fucoid research from New Zealand using Scopus searches, and extracted data about spatial locations, elevations, temporal patterns, study species, and study topics (Chapter 2). Data extractions from 430 papers showed that most kelp and fucoids were studied in central New Zealand, in the shallow subtidal zone (<30 m), over relatively short time scales (<2 years) and predominately in a single summer season. Furthermore, most studies were done on a multi-species community level typically showing distribution and abundance data. Ecklonia radiata and Durvillaea antarctica were the most studied kelp and fucoid species, respectively. I also identified a key research gap arising from few published studies on the early life history of fucoids – a research topic that is important for future protection and restoration projects. The systematic review was therefore followed by factorial laboratory experiments to determine optimal conditions to induce gamete release and grow zygotes of fucoids (Chapter 3). Experiments focused on reducing contaminants and specifically test for the relative importance of (a) temperature and heat stress on gamete release, (b) gamete solution-concentration and substrate types, slope, and rugosity on zygote settlement and (c) temperature, shading, fertilization, and competition with diatoms (through GeO2 addition) on germling growth and sizes. The first experiments compared propagule release between Hormosira banksii and other fucoids, but only Hormosira successfully produced zygotes that grew successfully on different substrates. Hormosira was therefore studied in follow-up experiments. First, I found that the release of Hormosira gametes and settlement of zygotes was greatest (when pooled over crossed test factors) at high zygote solution concentration (this single factor explained 10% of the data variability), at short stress duration of the parents (7%), at high temperature stress of the parents (6%), and when the slope of substrate slides was zero (2%) (there was no effects of slide rugosity). Second, in a longer 6-week zygote growth experiment, I found that germling densities were greater in fertilized aquaria (this single factor explained 21% of the data variability), without addition of GeO2 (8%, supposed to inhibit competing diatoms), and on Hardiflex substrates (7%, compared to slide substrates). However, adding shade cloth at two different temperatures (18 vs. 23°C) did not affect densities. Third, I found that factorial analysis on germling sizes was relative similar to the described analysis on densities. Finally, when evaluated across the different factorial experiments, only few higher order interactions were significant, and the significant interactions explained little of the data-variability, mainly varying in magnitude - not direction. This result suggests that effects on early life stages of Hormosira, by different environmental stressors, generally are additive. In conclusion, my work identified (a) key gaps to stimulate new kelp and fucoid research, e.g., associated with early life histories and restoration, and (b) environmental conditions that maximize success of early Hormosira life stages, which could improve future restoration aimed to rebuild and restore decimated intertidal Hormosira beds.
Open Access
The impact of employee and organisational purpose alignment : improving employee wellbeing and engagement through purpose congruence.
(2024) Morris, Conway
Organisational purpose has been found to hold an abundance of benefits for employees and the organisation alike, including improved motivation, longevity, life and job satisfaction, meaning, engagement, wellbeing, organisational resilience, long-term financial performance, higher customer satisfaction, reduced turnover intention and more. However, issues with the conceptualisation of purpose arise due to the inconsistency of constructs and scales utilised in this area. Additionally, it is unclear how a sense of purpose at work and views of organisational purpose interact to influence employee outcomes. The present study firstly distinguishes between perceived organisational purpose and sense of purpose at work. Secondly, it investigates the direct effects of perceived organizational purpose and its four internal dimensions of POPContribution, POPAuthenticity, POPGuidance, and POPInspiration, and individual sense of purpose at work on mental wellbeing and engagement. Thirdly, it looks at the effect of varying congruence and discrepancy levels with perceived organisational purpose and sense of purpose at work on the outcomes variables of mental wellbeing and engagement. An online survey with 202 working professionals was conducted, with polynomial regression and response surface methodology being used to explore the analysis. The highest levels of mental wellbeing and engagement were observed when there was congruence at high levels with perceived organisational purpose and sense of purpose at work, while the lowest levels of mental wellbeing were found when congruence was at low levels. Sense of purpose at work overall was found to be a much stronger predictor of mental wellbeing and engagement relative to perceived organisational purpose. The study underscores the importance of alignment between individual and organisational purpose in the workplace to maximise outcomes for employees.
Open Access
Engineering geology and geomorphology of the Coronet Peak landslide at Arthurs Point, Queenstown, New Zealand.
(2023) Rozmus, Kuba
The Coronet Peak Landslide (CPL) is located on the western edge of the Arrowtown Basin in Central Otago, in the lower South Island, New Zealand. Urban growth in key towns within Central Otago, like Queenstown is expanding, with the use of flat glacial-alluvial terraces being used up. The expansion has now reached areas characterised by new developments being located on steeper schist slopes, with increased geotechnical issues. The slopes within the Queenstown area are susceptible to instability due to a number of factors, most importantly lithology, foliation attitude, and rock/soil mass weakening linked to deglaciation. There are numerous documented large landslides in the region, and pressures for urban expansion have forced developments onto the lower slopes of these large landslides, such as the CPL. Understanding the associated hazard and risk of developing these large landslides is critical, as urban growth in the region is expected to continue for the foreseeable future. The primary objective of this thesis is to characterize the geomorphology of the CPL, specifically focusing on Arthurs Point. An additional objective is to characterize the slope debris of the CPL at Arthurs Point, referred to as chaotic schist debris. This research investigates the geomorphology and geotechnical properties of the landslide debris through geomorphic mapping using high-resolution imagery from lidar (2016 & 2021), recent aerial imagery (2021), and historical imagery (1956), alongside geotechnical subsurface investigations. This study uses eight 15 m deep boreholes, five 3 m deep test pits, and 12 piezometers, that provide the opportunity to characterise the slope material in detail. This research provides a detailed understanding of the slope material within the lower slope of the CPL at Arthurs Point, as previous investigations did not have access to high-resolution imagery. The CPL is a deep-seated gravitational slope deformation (DSGSD) characterized by multiple geomorphic zones with distinct features that result in differential instability of the slope. Although these large geomorphic features are considered to be relatively stable, under specific conditions, such as climatic changes, fluvial-glacial processes and human activity, secondary landslides associated with DSGSD can transform into catastrophic failure. There have been no recent documented large-scale failures within the CPL, but it is evident from the geomorphology that secondary landslide events have occurred on the toe in the past. Based on distinct surface morphologies across the CPL at Arthurs Point revealed by geomorphic mapping, the landslide is divided into four geomorphic zones: (A) the headscarp zone, characterised by distinct sackung features; (B) the main landslide body comprised of a hummocky topography; (C) the Shotover River reactivation, interpreted to be the most recent reactivation; and (D) the eastern reactivation with complex drainage and undulating, hummocky topography. No significant changes were identified between 1956 and 2021, however, comparison of the images over this time confirmed that zone C (the Shotover reactivation zone) is the most recently active zone due to current river scour and erosion of the toe of the zone. This study re-zones the previously mapped zone B of the CPL, and splits zone B1 into zone A (the headscarp zone) and zone B (the main landslide body zone). While no significant movement was observed over the 65 years, different geomorphic features are identified with the different sets of data between the recent lidar (2016/2021) and the 1956 aerial image. Due to changes in land cover and human modification of the slope, geomorphic features such as scarps, drainage paths, and other linear features, interpreted to be soil creep features, are more easily identifiable in the 1956 aerial image as opposed to in the lidar imagery. Geotechnical subsurface investigations of the chaotic schist debris at Arthurs Point show significant geotechnical variations of the material, with a large grading distribution of the material as well as a complex shallow groundwater system. Displaced competent schist blocks >10 m were identified in the field within a finer gravelly and silty micaceous matrix. Particle size distribution tests undertaken on one borehole (BH08) show the chaotic debris soil to be well and gap graded, with an average curvature coefficient, Cc, of 0.7 [ranging from 0.1–1.8] and an unconformity coefficient, Cu, of 27.6 [14–36]. Shallow perched groundwater is confined to the northwestern portion of Arthurs Point Woods development, with an average depth to groundwater of 2.32 m and an average pressure head of 9.7 m. Altogether, this study suggests that the Arthurs Point Woods residential development is placed in an unfavourable location within the toe of CPL based on the surface morphology, within a chaotic debris material that is weak and has a complex perched shallow groundwater system. Highly fissile, steeply overturned, and deformed schist was identified within the lower portion of the development, within the toe zone of CPL at Arthurs Point, suggesting stress relief and deep-seated gravitational processes. To ensure a comprehensive understanding of the subsurface conditions, additional geotechnical investigations should be carried out inside and beyond the boundaries of the development to fully understand the characteristics of the entire slope as well as the groundwater conditions. The combination of geomorphic mapping using current and historical imagery demonstrates that portions of DSGSDs can be identified and zones based on surface morphology and activity. However, ensuring the long-term stability for safe development on these slopes requires extensive site-specific geotechnical investigations due to their complexity.
Open Access
Differential diagnosis of pre-swallow pooling : a diagnostic dilemma.
(2023) Dragicevich, Dijana Maree
Accurate assessment and diagnosis of swallowing disorders is key to providing appropriate intervention. Selection of treatment relies on our diagnostic methodology. If incorrect treatment is selected, then swallowing disorders may not improve. Pre-swallow pooling is a feature of dysphagia that can cause aspiration before or during swallowing. It is presumed to be caused by two different pathophysiological impairments. One is presumed to be a motor impairment, which causes poor bolus containment as a result of oral weakness. This leads to some or all of the bolus entering the pharynx prior to purposeful propulsion of the bolus in the mouth. The other is presumed to be a sensory impairment whereby reduced sensation in the mouth causes a delay or absence of the pharyngeal swallowing response, after the bolus is propelled into the pharynx. However, assessment and diagnosis of pre-swallow pooling is poorly defined in the literature. In clinical practice, observations on videofluoroscopic swallowing studies are used to distinguish between poor bolus containment and delayed pharyngeal swallowing. However, videofluoroscopic swallowing studies allow for observation of biomechanics and cannot provide information regarding a sensory or motor impairment. Therefore, this PhD program investigated the phenomenon of pre-swallow pooling in stroke, to understand how it is differentiated into either poor bolus containment or delayed pharyngeal swallowing and whether a sensory and motor cause of pre-swallow pooling can be established. This PhD program of research involved four studies and a scoping review. The scoping review findings were included within the literature review for continuity. This identified a large variation of the terms used to describe pre-swallow pooling, the measurement methods, and the methods by which to differentiate poor bolus containment from delayed pharyngeal swallowing. Study one was a normative study on 60 healthy participants. This study evaluated normative and reliability data of a novel oral sensory threshold measurement, and posterior lingual-palatal pressure measurement and the relationship between them. Electrical stimulation was used to establish sensory thresholds in the mouth including the lips, tongue and faucial palate. Whilst lingual-palatal pressure norms have previously been reported, there is scant data on the posterior position that includes both isometric lingual-palatal pressure and lingual-palatal pressure during swallowing. The relationship between both physiological measures has not previously been investigated. Results suggest that there is some preliminary evidence that these tools can be used to determine a motor or sensory cause of pre-swallow pooling. Study two was the first study to evaluate the agreement of speech pathologists’ current methods for distinguishing poor bolus containment from delayed pharyngeal swallowing. This study evaluated inter- and intra-rater reliability of speech pathologist’s current practice in the diagnosis of poor bolus containment and delayed pharyngeal swallowing using videofluoroscopic swallowing studies. Thirty videofluoroscopic thin fluid swallows with five of those appearing twice, were presented via an online survey to examine agreement both between and within raters. Definitions of poor bolus containment and delayed pharyngeal swallowing were provided to one of two groups to evaluate whether this information increased reliability. Reliability was poor for inter and intra-rater reliability for both the group with, and the group without, definitions. This indicated that our current methodology for determining poor bolus containment from delayed pharyngeal swallowing is unreliable. Further, the addition of definitions to guide speech pathologists in determining one from the other did not increase agreement, suggesting that the application or interpretation of measures is too subjective. Study three was an exploratory study to determine whether distinct groups could be formed based on the physiological data obtained by the oral sensory threshold and posterior lingual-palatal pressure measurements. As there is no “gold-standard” for determining the difference between poor bolus containment and delayed pharyngeal swallowing, cluster analysis methodology was used to identify clusters that could be differentiated into one of potentially 3 groups. The groups were proposed to include a sensory group, a motor group, and a sensory-motor group. The aim was then to evaluate these groups against speech pathologists’ diagnosis of poor bolus containment and delayed pharyngeal swallowing in an attempt to determine whether a sensory and motor cause of pre-swallow pooling could be differentiated by clinicians. However, due to inconsistencies in speech pathologists’ diagnosis of poor bolus containment and delayed pharyngeal swallowing, this could not be completed. Since distinct groups could be established via cluster analysis, it is likely that evidence for a sensory and motor cause of pre-swallow pooling exists, however, our current methods for determining this is flawed. The final study evaluated the groups identified by the cluster analysis against common swallowing measures including oral transit time (OTT), stage transition duration (STD) and the Penetration-Aspiration Scale (PAS). Due to small numbers, most of the statistical methodology could not be applied, and results were presented descriptively. This research addressed the need for more consistent terminology to describe the two causes of pre-swallow pooling and improved methods for distinguishing between poor bolus containment and delayed pharyngeal swallowing. There is evidence that subjects who have pre-swallow pooling following a stroke can be separated into those who have both a sensory and motor impairment and those who have a motor impairment alone. However, there remains no evidence for linking poor bolus containment with a motor impairment and delayed pharyngeal swallowing with a sensory impairment. New methodologies for determining the cause of pre-swallow pooling are required to ensure correct selection of dysphagia intervention and optimise rehabilitation outcomes.
Open Access
Stimulation of murine ovarian cancer cell line ID8 clusters by ascitic fluid, observation of changes in cell behaviour, protein expression and post-translational modifications.
(2023) Papali’i, Noah
Epithelial ovarian cancer (EOC) has an exceedingly high mortality rate. Patients often are in the advanced stages of the disease at diagnosis due to lack of noticeable symptoms, and one of the first symptoms that patients present with is ascites. Ascites is a build-up of fluid in the peritoneal cavity due to loss of balance between fluid drainage and retention caused by leakiness of the peritoneal membrane. Ascitic fluid contains a mixture of different growth factors and cytokines which have the potential to change cell behaviour and correlate with survival, malignancy and efficacy of anti-cancer drugs. This study is interested in the effect that ascites has on the protein expression and post translational phosphorylation of ovarian cancer cells, both monolayer experiments and a more biologically relevant model using 3D non-adherent cell cluster cultures were run to confirm results were due to ascites treatment and not culture method. Murine ovarian cancer cell line ID8 cultured as both 3D cell aggregates and 2D monolayers were treated with ascites, the cell morphology, proliferation, proteins expressed and levels of phosphorylation for tyrosine and serine residues were compared to a control using methods such as 1D SDS-PAGE, western blot, and MALDI-TOF MS. We found that human high-grade serous ovarian cancer patient-derived ascitic fluid treatment has a significant effect on EOC model ID8 cell survival, and protein expression within floating cell clusters. Additionally, proliferation was significantly increased within cell monolayers. Protein expression change is potentially due to overexpression of glycolytic enzymes phosphoglycerate kinase 1 and alpha enolase, suggesting that constituents within ascitic fluid may act to trigger the Warburg effect commonly seen in cancer tumours. Later stage (more metastasised) ovarian cancer patient-derived ascites was suggested to favour an increase to ID8 cell cluster malignancy. Future studies are needed to determine the significance of MALDI-TOF MS findings within this experiment to determine the biological relevance to the population of human ovarian cancer patients as a whole.
Open Access
Residual meta-analysis : delay and probability discounting.
(2023) Gregoriadis, R. H.
Discounting is a fundamental process in human and non-human decision making. Although various quantitative models have been proposed to describe how people make trade-off decisions between reward magnitude, and delay or probability, there is no definitive answer as to the best model. Based on studies conducted in the past 25 years, a residual meta-analysis was conducted to provide a comprehensive evaluation of six prominent models of discounting. Two-parameter generalised-hyperbola and exponential models described delay and probability discounting very well, but systematic residual patterns were evident in the pooled residuals of all models. The bounded nature of the present value scale was excluded as a confound, and neither best-fitting model could be identified as the true model underlying the data. A weighted function suggested that a hyperboloid-constant sensitivity composite may better describe the decline of subjective present value. Notably, the same underlying functional form was identified for delay and probability discounting. Together, these findings suggest a novel model is required, that re-examines how delay (or odds-against) and reward magnitude are scaled, so that the true underlying discount function is accurately described.
Open Access
Industrial and organizational psychology and professional ethics in Aotearoa New Zealand.
(2023) Pond, Shane
The New Zealand Psychological Society’s Ethics Code describes the ethical principles that guide all Psychologists working in New Zealand. However, there is no research on whether the Code is adequate for industrial/organizational (IO) psychologists. This research explores the experiences of IO psychologists working in New Zealand and their perception of the Codes’ ability to achieve its three stated purposes. Structured interviews conducted explored the experiences of 12 IO psychologists working in New Zealand and thematic analysis was used to analyze their responses. Findings suggested that the Code in some cases fails to fulfill its purposes for IO psychologists. Issues include lack of guidance for the unique ethical dilemmas that IO psychologists experience. These findings suggest that there is a need to consider how the relevance of the Code is contingent on the differences between domains of psychology, and how the approach to managing ethics for IO psychologists practicing in New Zealand could be improved to better support and guide their ethical decision-making.
Open Access
Hierarchical reinforcement learning for the game of Othello.
(2023) Chang, Timothy
My thesis is about using hierarchical reinforcement learning to create a game playing AI to play the game of Othello, evaluating its strengths and weaknesses in this domain and providing more insight into hierarchical reinforcement learning. The game of Othello is an abstract strategy board game. There is an 8 × 8 board and there are two players, the white player and the black player. Each player takes turns to place one counter of their colour on the board. There are restrictions and rules about how and where counters can be placed. When counters are placed, they change the colour of other counters to be the same as the player that placed the counter. Counters are never removed from the board. The objective of the game is to have more counters of one's colour on the board than one's opponent when no more counters can be placed. (because the board has been filled or because the rules prevent either player from placing more counters on the board) Board games like Othello have long been topics for AI research as they require intelligent behaviour and writing a program to play well is a very difficult task. Computers are currently much better at playing abstract strategy games like Othello or Chess than humans. However, games like Othello still provide a good way to create or evaluate AI algorithms. As such, Othello is still being used as an environment for AI research. Playing Othello (or other similar sorts of games) at a strong level requires the player (be it human or computer) to have intelligent behaviour that makes actions based on the current state of the game. This presents a challenge for artificial intelligence. For example, a computer called "Deep Blue"[9] was created to defeat the world champion at the game of Chess. It required many hours of long work to develop the algorithms and software which eventually led to "Deep Blue" defeating the then reigning chess grandmaster Gary Kasparov. There are many different ways of making AI to play games like Othello. One is to use a search algorithm such as alpha-beta pruning[21] to find the best move. A search algorithm is an algorithm that looks into and analyses the possible futures of a game and then makes moves using the information it has gathered by looking into the game's potential future. Then there are other methods, such as constructing a set of rules that determine how the AI makes moves, (rule-based) statistical sampling (monte-carlo methods) and machine learning.
Open Access
Visual working memory : the roles of space-based, object-based, and feature-based attention within the same task.
(2023) Roscherr, Caitlin Megan
Visual working memory (VWM) is limited to approximately four items. Space-based, object-based, and feature-based attention have all been shown to enhance VWM. However, to our knowledge, no studies have examined them within a single task. In three experiments, we examined the effects of these three types of attention using a change detection task. In each experiment, participants saw a spatial cue, followed by a memory display consisting of four coloured circles. After a retention interval, a memory probe would appear. The task was to determine whether the probe matched the colour of a stimulus in the memory display. In Experiment 1, the memory stimuli were four different coloured circles and were grouped by task-irrelevant background rectangles. The probe stimulus could appear in the cued location, in the other end of the cued rectangle, or in a different rectangle of equal distance. Accuracy was higher in the cued location compared to both the same-rectangle location and the different-rectangle location, indicating a spatial attention effect. Accuracy was also higher in the same-rectangle location than in the different-rectangle location, suggesting an object effect. In Experiment 2, we additionally grouped two of the memory stimuli by colour, and the cue always indicated one of the colour grouped stimuli. The results showed that the stimuli with the grouped colour were responded to more accurately than the stimuli with ungrouped colours. Furthermore, for the stimuli sharing the same colour, there was no difference in performance regardless of whether the probed stimulus was cued or not, or within the same object as the cue or in a different object from the cue. These findings indicate a perceptual grouping by colour effect with no evidence of spatial or object-based effects. Experiment 3 further examined whether the spatial attention effect, or its absence in Experiment 2, was masked by the colour grouping effect due to the cue always appeared at the location of a grouped stimulus. We tested this hypothesis by manipulating the relationship between the location of the cue and that of a colour grouped stimulus so that the cue indicated the location of a grouped stimulus in some trials (cue-grouped), and the location of an ungrouped stimulus in other trials (cue-ungrouped). Among other results, the most important finding was a colour grouping effect with no spatial effect in the cue-grouped condition, but a colour grouping effect and a spatial attention effect in the cue-ungrouped condition. This pattern of data suggests that the absence of the spatial effect in the present study was due to spatial attention capturing both the cued stimulus and the same-coloured stimuli when the cue appeared at the location of a grouped stimulus. Taken together, these experiments clarify the conditions under which different attentional effects on VWM manifest, and how space-based, object-based and feature-based attentional effects work together within the same task to enhance VWM performance.
Open Access
Hydrogeology of the Eastern Southland Plains, New Zealand
(2001) Durie, Michelle Anne
The Eastern Southland Plains is situated between the Oreti and Mataura Rivers, and the area of approximately 45 km2 under investigation in this study includes the Morton Mains, Waimatua, and Kapuka coalfields. Farming is the principal land use in the region, particularly dairying, and groundwater resources are utilised widely. This thesis provides a detailed investigation of the Early Quaternary and Gore Lignite Measures aquifer systems by delineating the hydrogeological setting, groundwater trends and fluctuations, groundwater yields and water chemistry issues with specific reference to potability.
Open Access
Sediment and soil erosion and possible remediation scenarios in Governors Bay, New Zealand.
(2023) Evans, Joshua David
High rates of sedimentation in Governors Bay, Whakaraupō, New Zealand have led to the expansion of mesotidal mudflat and shallowing of the bay. This has been identified as a significant issue for local mana whenua, recreational activities, and fishing in the bay. Previous research has identified that this sediment is most likely drawn from the catchment immediately surrounding Governors Bay. This study aims to identify the source of the sediment in Governors Bay, better constrain its location within Governors Bay, and provide solutions in the form of possible remediation scenarios to enact to reduce erosion rates across the catchment. This was achieved through the acquisition and analysis of an 84 cm sediment core in Governors Bay as well as 36 sediment samples from the catchment to determine sediment provenance. This information was combined with InVEST sediment delivery ratio modelling software to identify areas of greatest concern in terms of sediment erosion as well as the land use types which contribute the most to sediment erosion and the types which can best be used to prevent it. Geochemical, total organic carbon and grainsize analysis of the sediment core and samples from the catchment identify the primary sediment source entering the bay as being that found below the 200 m contour in the catchment. This area corresponds to loess and loess colluvium stratigraphy and loess derived soils. Modelling of sediment erosion in the catchment suggests that the highest rates of erosion are found on hill slopes with grassland cover and in areas of urban development. Areas with the lowest rates of sediment erosion are found to be those with relatively flat topography and native forest cover. A remediation scenario is proposed to restore native forest to Governors Bay. The initial focus is suggested to be areas of grassland below the 200 m contour, with simultaneous removal of pests and weeds that would threaten native forest growth. Focus can then shift to reforesting the entire catchment in native forest over the long term apart from urban development. This scenario provides an effective option to reduce overall sediment erosion rates in the catchment, slow the expansion of the mesotidal mudflat to near natural growth levels, and to restore and prolong the cultural health of Governors Bay as well as securing future accessibility to the waters of the bay for the local community.