Science: Theses and Dissertations

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  • ItemOpen Access
    Lonely on limestone? A conservation genomics study of the Gentianella calcis complex.
    (2024) Eastman-Densem, Robb William
    Naturally fragmented or rare ecosystems are important components of terrestrial plant biodiversity. Unfortunately, many are also threatened through anthropogenic activities leading to increased extinction risk for their flora. In Aotearoa / New Zealand, the limestone areas of the eastern South Island / Te Waipounamu are a naturally fragmented and rare ecosystem of particular concern as they contain many highly threatened plant taxa. To assist with the ongoing conservation management of limestone endemic plants in New Zealand, the overall aim of this thesis was to explore patterns of genetic diversity and connectivity within a group of threatened limestone gentians (subspecies of Gentianella calcis and G. astonii) as well as investigate the interspecific taxonomic delimitation of G. calcis and G. astonii and infraspecific taxonomic delimitation of G. calcis. In Chapter 2, using Single Nucleotide Polymorphisms (SNPs) from 174 G. calcis and G. astonii samples genotyped through genotyping-by-sequencing (GBS), I aimed to determine the amount of genetic diversity in each subspecies and sampled population of G. calcis and G. astonii, assess the extent of genetic connectivity among them, and understand the geographic structuring of genetic diversity and its relationship to the environment. I show that all taxa are characterised by high population structure and limited genetic connectivity, with the presence of three main genetic groups corresponding to the South Canterbury and North Otago, Waipara, and North Canterbury and Marlborough regions. Although Isolation-By-Distance appeared to explain the observed patterns of genetic connectivity, potential adaptation to local climate and habitat soils was also seen. Patterns of observed heterozygosity potentially reflect past demographic histories as well as the effects of polyploidy-induced paralogy in some SNPs. Based on these findings, I designate conservation Management Units to assist with current and future conservation of G. calcis. DiscoSNP-RAD represents a novel SNP discovery approach that claims to not require the same parameter optimisation as other commonly used programs such as Stacks. There are very few published comparisons of its output to other SNP discovery programs, however, illustrating the need for empirical studies. Considering these factors, in Chapter 3 I aimed to assess the importance of using similarity-based parameters in SNP discovery by comparing both SNP discovery methods (i.e. Stacks and DiscoSNP-RAD) in terms of RAD loci assembled, data error, and population genetic inferences (e.g., estimates of population structure and genetic diversity). While both approaches provided similar patterns of population structure, estimates of genetic diversity and pairwise Fst differed between the two approaches. Using sample replicates, I show that this is likely due to increased SNP error in the DiscoSNP-RAD dataset, potentially reflecting a greater proportion of paralogy-induced SNPs caused by lower user control over the formation of RAD loci. Despite this, considering it has faster run-time and does not need extensive parameter optimisation, I suggest DiscoSNP-RAD is still a useful SNP discovery program. In Chapter 4, synthesising the learnings from Chapter 2 and Chapter 3, I make populationspecific management recommendations for each Gentianella calcis population along with taxonomic delimitation recommendations using knowledge of the genetic patterns in G. calcis and G. astonii. Considering that to date no conservation genetics or genomics studies have considered limestone plants in New Zealand at the population level, this research represents an important step towards the integration of genomic data into their conservation management.
  • ItemOpen Access
    Applying behavioural science to understand and support biosecurity risk assessments.
    (2024) Bain, Dominic
    Invasive species threaten the health, safety, sustainability, wellbeing, and prosperity of Aotearoa New Zealand. A key function of the biosecurity system is to comprehensively assess the risks posed by invasive species. This study investigated the psychological dimensions of biosecurity risk assessments and explored potential targets and mechanisms for improvement. Twenty participants were recruited from Aotearoa New Zealand’s biosecurity workforce. Policy capturing, multiple-criteria decision analysis, and the behaviour change wheel were used as investigative frameworks. Results from the policy capturing analysis indicated that risks to economic, environmental, sociocultural, and te ao Māori values all significantly increased participants’ perception of invasive species’ overall biosecurity risk. Risks to economic values had the largest effect and risks to sociocultural and te ao Māori values had the smallest effects. Results from multiple-criteria decision analysis indicated that participants consciously allocated the most importance to risks to economic values followed by risks to environmental, then sociocultural, and then te ao Māori values. Results from the behaviour change wheel analysis indicated that participants were motivated to incorporate te ao Māori values into their biosecurity risk assessments but perceived that they lacked the capability and opportunity to do so. Key intervention targets and mechanisms were discussed to address these areas and support comprehensive biosecurity risk assessments.
  • ItemOpen Access
    Does a dimensionally-gated reselection process restrict the entry of visual features into working memory?
    (2023) Williamson, Kieran James
    Visual working memory (VWM) is a limited-capacity cognitive system that allows us to maintain and manipulate visual information over a brief period of time. It plays a critical role in many cognitive functions, including visual search, problem-solving, and decisionmaking. While the importance of VWM is not disputed, a critical issue addressed in research is whether visual objects bind all their component features during VWM entry or if task-relevant features are prioritised for representation. In a recent study, Zhu et al. (2022) proposed that attended sensory information does not automatically enter VWM, but instead is subject to an additional reselection process that determines whether items are selected for VWM entry. Furthermore, they suggested that reselection operates using a dimensional memory filter, such that when an individual feature value (e.g., red) is selected for entry into VWM, all attended feature values within the same feature dimension (e.g., all colours) automatically enter VWM. Across three experiments, we systematically investigated these hypotheses by conceptually replicating two of Zhu et al.’s experiments, while incorporating modifications to address our concerns about their methodology. In Experiment 1, we investigated Zhu et al.’s proposal that a reselection process operates to restrict the entry of features into VWM. We assessed whether the irrelevant colour of a target object captured more attention than a new colour when it appeared as a distractor singleton in an orthogonal visual search task. We found that this was the case, indicating that the irrelevant colour of the target object was held in VWM, contrary to the key result that Zhu et al. cited to support reselection. In Experiments 2 and 3, we investigated Zhu et al.’s claim that VWM consolidation operates via a dimensional memory filter. Specifically, we assessed whether memorising the colour of a fixation cross would cause the task-irrelevant colour of a target object to enter VWM. To determine whether this colour entered VWM, we measured its interference in an orthogonal shape change detection task. Experiment 2 used a 700 ms ISI, while in Experiment 3, we reduced the ISI to 100 ms. Unlike Zhu et al., who only reported trials where shape was consistent between displays, we included trials where shape changed between displays in our analysis and included trials in which the shape probe matched the memorised fixation colour. In Experiments 2 and 3, we found evidence that the target colour had entered VWM, consistent with a dimensional memory filter. However, we also found that the fixation colour had a stronger impact on shape change detection than the target colour, a finding that was not explicitly predicted by Zhu et al. Overall, our results align more closely with predictions from object-file theory (Kahneman et al., 1992) and event-file theory (Hommel, 1998, 2004), which propose object-specific binding occurs during encoding, and objectspecific benefits and costs emerge during object retrieval and review. The facilitation we observed when features were consistent between displays could reflect objectspecific repetition benefits, while the interference we observed when features partially changed between displays may indicate partial repetition costs.
  • ItemOpen Access
    Freedom from exposure to intimate partner violence in early childhood and emotional regulation during middle childhood, among pacific childhood growing up in Aotearoa/New Zealand.
    (2023) Hakeemi, Humaira
    Background: Studies have consistently demonstrated that children exposed to intimate partner violence (IPV) are at a higher risk of experiencing behavioural, physical, and emotional problems. Recent findings from a longitudinal study revealed that within the Pacific Islands Families (PIF) cohort, 41% of mothers identified themselves as either victims or perpetrators of IPV, highlighting the prevalence of such violence in the lives of children. Emotional regulation plays a critical in a child's development and well-being, emphasising the importance of investigating early childhood experiences to understand the factors that shape emotional health and identify protective measures. This study significantly contributes to a deeper understanding of the unique needs and experiences of Pacific children, thereby facilitating the development of targeted interventions tailored to this specific population. Given that PIF communities often contend higher rates of IPV compared to other demographic groups, this study aims to illuminate the distinct challenges they confront. Research Aim: The purpose of this study was to examine the relationship between freedom from exposure to IPV during early childhood (2-years) and emotional regulation during middle childhood (9-years), among Pacific children growing up in Aotearoa/New Zealand. Methods: This study utilized the PIF study, a longitudinal birth cohort study providing comprehensive data on the development of Pacific children in New Zealand. The study’s participants consisted of Pacific infants born at Middlemore Hospital in Auckland between March 15 to December 17, 2000. A total of participants completed both the IPV questionnaire and the internalising problems questionnaire. IPV exposure in children was assessed using mothers' reports at the 2-year measurement wave, while internalising problems were evaluated based on reports from mothers, teachers, and children at the 9- year measurement wave. Additionally, the study examined a child's report at the 9-year measurement wave to explore potential factors, such as substance exposure and bullying, in the relationship between IPV exposure and internalising problems. Result: While the study did not find a direct association between mother-reported IPV exposure and subsequent internalising problems, it did yield several significant findings. Children self-reported significantly higher rates of internalising problems than anticipated, with the severity of violence exposure notably impacting these rates. Specifically, children who reported symptoms were 2.2 times more prevalent among those whose mothers reported severe violence. Furthermore, mothers reported higher rates of internalising problems compared to children in a US-based standardization sample. This study also identified that children who had experienced bullying were at a 1.45 times increased risk of internalising problems, a pattern consistently reported by the children themselves. Additionally, the findings from this study indicated that children with access to any form of substance were found to be at a 3.27 times higher risk for internalising problems when compared to children without substance use. Despite the sample’s diversity, this study did not reveal any influences of cultural orientation on the relationships between preschool physical IPV exposure and middle childhood internalising problems. Implication: It is important to interpret these results within the existing literature and acknowledge the study’s limitations. The recruitment strategy used in the PIF study may restrict the generalizability of the results, given that the study’s participants were restricted to infants born at Middlemore Hospital and within the PIF study regions. It is possible that individuals from other regions in New Zealand may experience internalising problems differently. The relatively small sample size of 623 participants in this study could also affect the generalizability of the results, potentially yielded different outcomes with a larger sample. Previous research has produced varied results concerning the association between IPV exposure and children’s internalising problems, with some studies demonstrating significant associations and others showing no significant effects. This complexity underscores the necessity for further investigation to gain a more profound understanding of the underlying mechanisms and potential moderating factors involved.
  • ItemOpen Access
    Response biases in visual processing: the effect of similarity and attention on judgments of sameness.
    (2023) Humphries, Ailsa M.
    It is well known that humans exhibit biased behaviours. Research suggests that both perceptual and cognitive biases arise from adaptive solutions to situations in which decisions must be made in the absence of complete information. These biases result from the operation of heuristics, or mental shortcuts, that evolved to keep us safe; to orient us towards friend and away from foe. While some biases are considered negative, leading to prejudice and discrimination, many are not; they are simply interesting tendencies that are worth studying to better understand information processing. Research in visual comparison tasks has identified two key biases. The spatial congruency bias (SCB) is a relative bias, with a greater tendency to judge objects as “same” if they are presented at the same location compared with a different location; and the overall bias (OB) is the average bias across all trials, that varies with overall display similarity and the degree to which analytic processing is required. Studying these biases will help with understanding the visual processing mechanisms that underlie object comparison, a fundamental task in our everyday activities. In two studies, signal detection theory was used to measure response bias and calculate the SCB and OB in visual comparison tasks that required judging whether two objects were the same or different. Each trial consisted of two sequential displays (S1 and S2). Each display contained a 3x3 grid with a target object in the middle row and two distractor objects, one in the top row and one in the bottom row. Participants judged whether the shape and/or position of a target object was the same or different in S1 and S2. There were two key manipulations common to both studies. Firstly, within every experiment the relative location of the grid between S1 and S2 was manipulated to assess the SCB. The grid was in the same location from S1 to S2 on half the trials and a different location on the remaining trials. Secondly, between experiments, the similarity of the distractor objects was manipulated with respect to the task relevant feature (i.e., their shape in the shape judgement task and their position in the position judgment task). The distractor objects either remained the same from S1 to S2 on most trials (high similarity) or they changed from S1 to S2 on all trials (low similarity). Study 1 was designed to investigate how location and display similarity affect response biases, and how those effects differ for position judgements versus shape judgements. Previous research has focused on investigating the SCB in judgments of object features such as shape and colour. In the first two experiments the task moved beyond feature comparisons, requiring comparison of the local position of the target (a black dot) with displays that had high similarity (Experiment 1) or low similarity (Experiment 2). The next two experiments directly compared the SCB and OB in position judgments versus shape judgments in within-subjects designs using letter stimuli; again, displays had high similarity (Experiment 3) or low similarity (Experiment 4). Together, the results of these experiments revealed that the SCB is a general phenomenon that applies to both position and shape comparisons, and is consistent regardless of stimulus type (dot or letter). Further, the SCB was weakened and the OB shifted more towards “different” when similarity was low, and the OB was shifted more towards “same” in position versus shape comparisons. The pattern of results suggests the SCB indexes the operation of a visual heuristic that is linked to the privileged nature of location and is evoked more often when similarity is high. Furthermore, as attentional selection requirements increase, due to the nature of the task and/or differences between displays, the tendency for “different” response increases. Study 2 was designed to determine whether an attentional mechanisms account, in which bias is modulated via adjustments to attentional zoom, or an overlap measure account, in which bias is modulated via an interaction between the number of differences and the threshold for a “different” response, is more parsimonious as an explanation for the effect of similarity on response bias. Previous research has indicated that the extent of attentional focus is adjusted to optimise target selection when the position of the target is predictable. In four experiments the position of the target letter was manipulated in the shape comparison task: it either remained in the same position from S1 to S2 or changed position, and this manipulation was either predictable (Experiments 5 and 7) or unpredictable (Experiment 6 and 8). Further, distractor similarity again varied from high (Experiments 5 and 6) to low (Experiments 7 and 8). The results revealed that reduced similarity affects response bias when either distractor shape or target position changes, and the predictability of target position only modulates bias when distractor similarity is low. The pattern of results suggests that mechanisms inherent in the overlap measure account provide a sufficient explanation for variation in response bias when holistic processing is possible, and that attentional mechanisms play an important role when analytic processing is required. In summary, a complex interaction between multiple factors influences response bias in visual comparisons. The SCB manifests as a result of the privileged nature of location which underpins a key heuristic, “same-location = same-object”, and the strength with which this heuristic is evoked varies with overall display similarity and attentional zoom settings. Visual similarity influences both the operation of the heuristic and the overall tendency for a “different” response via an interaction between the overlap measure, a “difference count” from the direct comparison of two displays, and the threshold for a “different” response, that develops on the basis of the heterogeneity of differences across multiple trials. Both biases are further modulated by attentional mechanisms that operate to adjust attentional zoom settings when experience with the task and/or displays indicates that analytic processing is optimal.
  • ItemOpen Access
    The application of the slope stability probability classification system to opencast mining in the Waikato Coal Measures, New Zealand
    (2000) Campbell, Richard Nathan
    A major factor in successful and economic opencast coal production is the ability to develop an understanding of the engineering behaviour of the overburden rock that must be removed to expose the economic material. The Waikato Coal Region is New Zealand's largest coal producing area, the majority of which is extracted by opencast methods. The Slope Stability Probability Classification (SSPC) system of Hack (1998) has been applied to the problem of slope stability assessment within the Waikato Coal Measures, which are the basal formation of the predominantly transgressive Te Kuiti Group, of which the economic coal commonly occurs at the base of the coal measure Ethologies. The research undertaken concentated on the Rotowaro and Maramarua Coalfields, which are located in the central and northern sectors of the Waikato Coal Region respectively. Many of the best known and well documented rock mass classification systems were originally designed for the classification of rock masses in which civil engineering tunnels and caverns are to be excavated, and are thus not well suited to the classification of surface excavations and opencast mining applications. Many of the geotechnical classifications that have been applied to the engineering of slopes in opencast mines (i.e. SMR and MRMR) are adapted versions of Bieniawski's (1973) original RMR system and as such contain input parameters that may not be applicable to slope stability. The SSPC system is one of the few geotechnical classification systems that has been developed specifically for the application to slope engineering. The engineering geological field data was collected from 22 scanline surveys in the Township and Gunclub Pits and along the Township Northern Highwall in the Rotowaro Coalfield and the Kopuku Pit in the Maramarua Coalfield. Laboratory testing data was collected to characterise the Waikato Coal Measure lithologies, in terms of strength (UCS), triaxial, durability, swelling and sonic velocity. The resultant data has been applied to the SSPC system and the rock mass cohesion, friction angle and rock mass strength output results have been compared to those of the SMR, MRMR and Modified Hoek-Brown Failure Criterion in an effort to test the previously untrialed (in the mining environment) SSPC system against the results obtained from these better known and evaluated classification systems. The SSPC system produced comparable design rock mass values (cohesion, friction angle and rock mass strength) to the other classification systems with the additional feasibility design tools of the orientation-independent and orientation-dependent stability analysis. The orientation-independent stability function of the SSPC has proved to be a useful design tool for identifying the maximum stable batter height for a particular batter angle in terms of probability of failure. The orientation dependent stability analysis has also proven to be a powerful tool for identifying which batter orientations (dip-directions) are preferable in terms of acceptable probability of failure for both the sliding and toppling failure mechanisms. After assessing the applicability of the SSPC system to coal mining in the Waikato Coal Measures the SSPC system was applied to a orientated and geotechnically logged drill hole as a test of its use as a feasibility assessment tool. The drill hole case study illustrated the usefulness of the SSPC as a feasibility design tool, and provided a similar estimation of the rock mass cohesion friction angle and rock mass strength parameters as complex and time consuming numerical analysis. The stability probability functions determined the maximum stable batter heights and dip angles based on the acceptable probability of failure. The orientation dependent stability analysis identified which of the proposed batter orientations had a higher than acceptable probability of failure and thus should be avoided.
  • ItemOpen Access
    Aspects of the social behaviour and management of African antelope at Orana Park, Christchurch
    (1991) Cameron, Elissa Z.
    Sitatunga (Tragelaphus spekei), Waterbuck (Kobus ellipsiprymnus), Scimitar­ horned Oryx (Oryx dammah), Springbok (Antidorcas marsupialis) and Addra Gazelle (Gazella dama) were studied in captivity from November, 1989 to December, 1990 at Orana Park, Christchurch. All species are of different taxonomic groups, and come from a wide range of habitats. Three of these species (Sitatunga, Scimitar-horned Oryx and Addra Gazelle) are little studied in their wild habitats. Captivity provides many opportunities for studying animals from inaccessible habitats without the logistic problems of research in the wild, for testing theoretical hypotheses, and for studying species management for conservation. The principle objectives of the study were to examine aspects of social behaviour, daily activity, and grouping patterns and to devise optimal management strategies. The social and expressive behaviours of the species were recorded. I present some behaviours that have never before been described in these species. Behaviours described include general behaviours, threat and dominance displays, fighting, submission, courtship, mother-young interactions, play and alarm behaviours. Daily activity patterns were similar to wild patterns of daily activity and were related to the feeding ecology of the species. Predator disturbance on Scimitar-horned Oryx caused an increase in vigilance behaviour at the expense of feeding, lying and maintenance behaviours. Daily activity patterns of Scimitar­ horned Oryx were also affected by temperature and weather conditions. Although behaviour patterns were different for each species, the patterns were influenced by a number of proximal factors. Species from open habitats tended to associate closely, whereas species from closed habitats associated loosely, and females associated more closely than males and calves. I hypothesised that the differences were because of different anti-predator strategies and, in the case of males compared to females, relative aggression. In Scimitar-horned Oryx I found that predator disturbance caused an increase in association, whereas increased aggression caused a decrease in association, supporting the hypotheses that association patterns are largely affected by anti-predator strategies and relative aggression. Near linear dominance hierarchies existed in Sitatunga, Scimitar-horned Oryx, and Waterbuck. Social rank value was correlated with aggression in all species. In Scimitar-horned Oryx the presence or absence of horns affected social rank value due to the impaired fighting ability caused by loss of horns, but horn size did not effect social rank. Management was studied in all species by relating previous work to the ideals of management. Recommendations were made suggesting how animals may be better exhibited to enhance their welfare and suitability for reintroduction to the wild. Sitatunga were chosen as a case study as problems of enclosure design were evident. The presence of water and cover increased the amount of time Sitatunga spent in view. It was suggested that a swamp-like enclosure, with viewer observation from above, would enhance both the animals' comfort and the education potential of the enclosure.
  • ItemOpen Access
    The effects of temperature and emersion on the respiratory physiology of the New Zealand lobster Jasus edwardsii in air and water
    (1999) Pritchard, Michelle M.
    The New Zealand lobster Jasus edwardsii is the basis of a major seafood industry, where the majority of lobsters caught are exported alive. There is a lack of physiological information regarding the design, management, transport and holding of live lobsters. The main aim of this study is to understand the effect of temperature and emersion on the respiratory physiology of the New Zealand lobster. Resting oxygen consumption increased with acute temperature change. When Jasus edwardsii was exposed to 5°C lobsters experienced a cold coma. Diurnal rhythm had no effect on the resting oxygen consumption. Lobsters did not show metabolic temperature compensation, actually showed reverse or paradoxical compensation i.e. lowered M0 2 after 2 weeks in a cooler environment. There was an initial decrease in oxygen consumption at 5°C, 12°C and 18°C following aerial exposure, this was followed by a partial recovery at 12°C and 18°C. Resting aerial oxygen consumption increased with temperature. L-Lactate and ammonia had accumulated in the haemolymph of lobsters at the end of each emersion period. Hence lobsters still rely on anaerobic metabolism even at temperatures as low as 5°C in air. There was a initial decrease in Pa0 2 and the oxygen content of the haemolymph when lobsters were emersed. pH initially decreased at all three temperatures and then tended to stabilize. Lactate steadily accumulated in the haemolymph at the three temperatures. The haemocyanin oxygen affinity increased during prolonged emersion (measured in vitro at a constant pH). This increase was probably due to a rise in lactate concentration of the haemolymph. Oxygen coductance of the gills decreased on emersion at 12°C but was partially restored between 4 and 24 hours. However, the rate oxygen consumption of lobsters during emersion was not affected by the quantity of water in the branchial chamber. Thus it is concluded that the major factor leading to restoration of MO2 in air is lactate-induced increase in the affinity of haemocyanin for oxygen. This study developed the understanding of the effects of temperature on the metabolism of the New Zealand lobster Jasus edwardsii in air and water. The information in this study is useful to the design and management of future lobster holding facilities.
  • ItemOpen Access
    Biology of Spelungula cavernicola Forster (Gradungulidae), a New Zealand cave-dwelling spider
    (1993) McLachlan, Andrew R. G.
    Spelungula cavernicola, New Zealand's largest and only protected native spider, was studied for one year in caves in the Honeycomb Hill System, Oparara Valley, near Karamea, South Island. These spiders were found mainly in complete darkness within 10 or 20 m of a cave entrance, but were also present deep in the caves. The numbers of spiders recorded through the year showed little temporal variation except when juveniles emerged from egg sacs. Some short-term variation in numbers may be due to migration in and out of sites, or variable search effort, or both. Spiderling emergence from egg sacs may be seasonal,. but size class data suggest that the timing. of emergence differed between years. The hypothesis that Spelungula lives only one year_ was refuted using size-class data. All size-classes of animals were present all year, and except for newly emerged spiderlings, occurred in uniform proportions, giving evidence of overlap of generations. Two estimates of longevity from size-class data are 3 years and 5 years, which may be underestimates because adult longevity could not be estimated. A preliminary investigation of habitat selection of Spelungula was made using multiple logistic regression of 84 random cave sites. Presence of cave wetas was a significant variable, whereas, passage size, light, water, temperature, humidity, presence of other animals, and distance to cave entrance were not. The implications of these results for conservation management are discussed.
  • ItemOpen Access
    Co-seismic disturbance of alluvial fans
    (2001) Cole, Peter Roger
    A series of alluvial fan models were built using a mixture of sand and water on an adjustable flume base, capable of reproducing normal faults and shallow anticlinal folding across the width of the fan. The surface of the fans was measured and photographed at regular intervals and comments recorded. Field studies gathered evidence of exposure to a risk of flooding to some occupants and to public services on the Waiho River Fan on the West Coast of New Zealand. Further field evidence found a soil age anomaly on the Fox/Cook Fan leading to a reconsideration of the fault/fan processes involved at that location. The modelling results indicate that just as significant, if not more so, to river flow behaviour across alluvial fans is the content of bedload sediment rather than the dislocation and initial riverbed level change of the primary channels, following a seismic event. The results also suggest that there is a high likelihood of a major avulsion of the Waiho River as a result of co­seismic influences on the river fan and as a consequence, an appreciable risk to life and property at Franz Josef Glacier from the Waiho River after movement of the Alpine Fault. The modelling results also support the hypothesis that rather than a surface expression as a fault scarp, the Alpine Fault is causing the ground beneath the Fox/Cook fan to fold, creating an alluvial 'island' and forcing the river to entrench into ever deepening channels.
  • ItemOpen Access
    Voice hearing in dissociative identity disorder: a qualitative investigation using interpretative phenomenological analysis
    (2024) Wilson, Miceál C.
    Individuals diagnosed and undergoing treatment for dissociative identity disorder (DID) typically report hearing voices in the absence of any external source, yet this experience is not well understood. This thesis used interpretative phenomenological analysis to investigate the lived experience of voice hearing in the context of the therapy journeys of 12 individuals with DID. Study One (n = 6) broadly resulted in four group experiential themes: ‘voices are communication from different parts of the self with independent identities’, ‘voices emerged as a response to traumatic life events’, ‘voice hearing has negative impacts’, and ‘therapy has offered insights’. A second study (n = 6) explored voice hearing in relation to sense of self and resulted in two group experiential themes: ‘voices are communication of dissociative identities’, and ‘voices diverge from personal ‘owned’ thoughts’. The results of both studies support the notion that the experience of hearing complex, person-like voices may reflect the experience of dissociative fragmentation of self into ‘parts’. Additionally, voices may sometimes be experienced as thought-like, yet will often be differentiated by their unbiddenness, their disconnection from one’s own thoughts, and their ‘not-me’ quality. The findings of this study provide a means for furthering steps in treatment development, and a basis for future investigations.
  • ItemOpen Access
    Avoidant/restrictive food intake disorder (ARFID) in New Zealand: clinical characteristics, psychosocial impact, perceived contributing factors and treatment
    (2024) Wells, Georgia Rose
    There are six aims of this exploratory mixed methods research. Aim one is to compare the demographic information of each group including age, gender and ethnicity. Aim two is to compare the clinical characteristics of each group including the age of eating disorder onset and recovery status. Aim three is to compare the groups in terms of reported medical and mental health disorder experiences. Aim four is to describe and compare the groups perceptions of factors which contributed to the development of their eating disorder. Aim five is to compare and describe the differences in the psychosocial impacts experienced by each group and aim six is to describe whether each group accessed treatment and if so, describe the nature and duration of treatment and their satisfaction with the treatment quality they received. The findings of this research will be presented, along with supporting literature in the following order: Chapter one of this thesis aims to outline the literature surrounding eating disorders broadly, including definitions, common comorbid disorders, prevalence, impact, aetiology, prevalence and risk factors specific to children and adolescents. Chapter two of this thesis is an overview of Avoidant/restrictive food intake disorder (ARFID), its proposed subtypes, its development as a diagnostic criteria, ARFID presentation in children, common comorbidities, prevalence, aetiology, treatment and the impact of ARFID. Chapter three of this thesis discusses the methodologic approach including the study design, ontology and epistemology as well as the methods of this thesis sub-study including study design, participants and materials. Chapter four outlines the qualitative results. This is divided into six parts, with one part answering each aim of this sub-study. This chapter also outlines the quantitative results which is divided into three parts, answering aims four, five and six of this thesis sub-study. Chapter five discusses the results together including their importance, limitations and direction for future studies. Although this research has been conducted in a population over the age of 16, research from child and adolescent populations is commonly referenced. The inclusion of research from both adult and child/adolescent populations is due to the nature of ARFID being a disorder more common in children and therefore, more research is conducted in these populations. A substantial amount of literature surrounding eating disorders and ARFID in children/adolescents is also included due to the nature of the degree being child and family psychology.
  • ItemOpen Access
    Investigating the detection sensitivity of the mismatch response in normal hearing adults: a study using complex tones with high ecological validity, in the application of validation of infant hearing aid fittings
    (2024) Liu, Xu
    Background: Permanent congenital hearing impairment has a high prevalence and can negatively impact the development of the auditory cortex, especially during the critical first few years of life. To address this, worldwide initiatives have implemented newborn hearing screenings and early intervention programs, enabling the diagnosis and fitting of hearing aids in children as young as two months old. At such an early age, where subjective feedback is limited or unavailable, objective validation tools become crucial. Amongst current and emerging electrophysiological objective tools, most focus on assessing audibility of aided speech sounds. The Mismatch Response (MMR) on the other hand, is notable for its ability to assess both audibility and discrimination of speech sounds. MMRs can be recorded in sleeping or awake infants and exhibit a high response detection rate (>90%) based on recent data but for coarse discrimination tasks. This study aims to determine the response detection rate for of MMRs when the differences between speech-like sounds are more subtle. Design: MMRs were measured in 13 normal hearing adults, using an optimised 4-deviant paradigm in response to complex tones (CTs) with a centre frequency representative of the first formant of five common English vowels, in the frequency range of 536 Hz to 753 Hz. Results: Objective response detection analyses using the Hotelling’s T2 statistical method revealed that the detection rate of MMR for stimulus pairs with approximately 20 Hz spectral difference was low (40% or lower). Conversely, for most stimulus pairs with a spectral difference exceeding 80 Hz, the detection rates were notably higher, at 80% or above. Conclusion: A spectral difference of 20 Hz between CTs is too small to elicit reliably detectable MMRs at the level of the individual listener, although some elements of natural speech are characterised by such small spectral cues. However, when the difference limen between the CTs was at least 80 Hz we found an MMR detection sensitivity that might be considered acceptably high for the clinical setting.
  • ItemOpen Access
    The carrying capcities [i.e. capacities] of huts and tracks inside Mount Cook National Park
    (1995) Druce, Daniel Matthew Ishtar
    The social carrying capacities of huts and tracks inside Mount Cook National Park are explored within the contexts of current approaches to the management of natural areas. Data was collected, during March and April 1995, from 391 questionnaires, at four sites; the Blue Lakes, Hooker Valley, Mueller Hut and Hooker Hut. Due to the physical constraints on access, each track was seen to offer different recreational opportunities. A review of the carrying capacity literature provides the theoretical basis for this research. Theories of perceived crowding, social norms and frameworks for managing natural areas are seen to emphasise 'change' in settings rather than restrictions of use. Results indicate that perceived crowding is an appropriate method for defining social carrying capacity in recreation areas. The use of social norms did not define acceptable levels of use. Analysis of perceived crowding found that the Hooker Valley and Mueller Hut had exceeded their social carrying capacities. Yet users still reported high levels of enjoyment from all four sites. It was suggested that this was due to coping behaviours being utilised in 'crowded' situations. Results are applied within the Limits of Acceptable Change planning framework. This places subjective limits of acceptable change within the study sites and examines how these limits could be measured in Mount Cook National Park.
  • ItemOpen Access
    Response of micro-eukaryote and slime mould communities to land use change and pine invasion in Aotearoa
    (2024) Cox, George R.
    Soil micro-eukaryotes are a highly diverse group that drive key biogeochemical cycles and regulate the communities of other soil microorganisms, yet their responses to ecosystem changes in Aotearoa New Zealand are unknown. Micro-eukaryote communities are highly responsive to changes in soil conditions such as soil moisture and carbon availability, with these community level responses often differing from those of other soil biota. Human activity has changed many ecosystems in Aotearoa with the shift from native beech (Nothofagus sp.) to open shrublands, and now to exotic pine forests being one of the most notable. These large-scale changes in plant community composition have impacted animal, bacterial, and fungal communities within the soil, in addition to changing soil abiotic factors like nutrient ratios. This thesis aims to test the impacts of land use change and particularly pine invasion on soil micro-eukaryote communities in Aotearoa, to fill this research gap. I extracted soil DNA from 33 sites in the Molesworth Recreation Reserve, with the sites being split between mountain beech (Nothofagus cliffortiodies) forest, native dominated grass-/shrublands, and invasive pine stands. A general eukaryote primer was used to generate OTUs (operational taxonomic units) via DNA metabarcoding to reveal the community level changes of micro- eukaryotes between different vegetation types. Slime moulds, a subgroup of micro-eukaryotes, were surveyed and cultured from these same sites to supplement the sequencing data. DNA metabarcoding revealed that shrubland sites had significantly higher OTU richness and effective diversity than pine sites. Community dissimilarity (beta diversity) was also higher in shrubland sites than either beech or pine sites. The soil micro-eukaryote communities of all sites were dominated by the Cercozoa, with the Apicomplexa, Ciliophora, and Amoebozoa also identified as key soil micro-eukaryote groups in Aotearoa. The collected slime moulds did not significantly differ in diversity or community composition between vegetation types but did reveal multiple novel sequences and the detection of four species in Aotearoa for the first time. The slime mould communities of these sites were dominated by the genus Didymium, with most other slime moulds belonging to the family Physaraceae. Land use change and pine invasion do impact the soil micro-eukaryote communities of Aotearoa, with pine invasion into shrublands leading to a reduction in micro-eukaryote diversity. However, these changes may be returning the soil micro-eukaryote community to a more natural state, as beech and pines forests shared similar levels of diversity. The community level responses of micro-eukaryotes to anthropogenic changes differ from those seen in other soil biota where beech forest usually hosts the most diverse communities. Further work should be done to identify the specific drivers of change in these micro-eukaryote communities. The taxonomy of the collected but unidentified slime moulds should be investigated further to either complete online sequence database or reveal novel taxa.
  • ItemOpen Access
    Ion implantation in β-Ga2O3 thin films
    (2024) Sinclair, Andrew
    As silicon devices are pushed to their physical limit, there is currently significant academic and commercial interest in wide band gap, and ultra wide band gap semiconductors which can operate at high power densities. One such semiconductor, β-Ga2O3, is seeing significant attention in recent years due to its high band gap (4.5 - 4.9 eV), and breakdown field (8 MV/cm) which makes it a desirable material for the manufacture of high power devices and photoelectronic devices operating in the deep ultraviolet (UV) region. n-type doping of β-Ga2O3 can be increased through the use of ion implantation with Si, Ge, and Sn substituting Ga in the crystal. Monte Carlo simulations of Si, Ge, and Sn implantation in β-Ga2O3 were undertaken to determine an implantation procedure that would result in a uniform dopant concentration of 1 × 1018 cm−3 and 1 × 1019 cm−3. This implantation procedure was used to implant Si into six thin films of Ga2O3, including two grown by Molecular Beam Epitaxy (MBE) on MgO (100) substrates, two by MBE on c-plane Al2O3 (c-Al2O3) substrates, and two grown by the sol-gel process on c-Al2O3. The implanted thin films underwent thermal annealing over a temperature range from 950 ◦C to 1100 ◦C to restore damage resulting from the implantation process. The effect of annealing on the electrical, optical, and material properties of the samples was examined using UV - Vis transmission spectroscopy, X-ray Diffraction (XRD) crystallography, Atomic force Microscopy (AFM), and Hall effect measurements. Electrical measurements indicated Si implantation failed to produce conducting thin films. Results of XRD measurements and UV-Vis transmission measurements indicate that this is likely due to the diffusion of Mg and Al in the substrates into the β-Ga2O3 films, which prevents the activation of Si by occupying Ga sites.
  • ItemOpen Access
    Investigating the mental health of autistic trans youth in Aotearoa New Zealand
    (2024) Jones, Harry M.
    Youth who identify as either transgender or Autistic are part of highly stigmatised minority communities that suffer many inequities in mental health and wellbeing. In the face of marginalisation, Autistic trans communities are resilient, vibrant, and embody solidarity. International research with Autistic trans youth has observed them to be at greater risk of anxiety, depression, and suicidality than the general youth population, and to have poorer mental health than their allistic trans peers. Previous research has shown that Autistic and trans communities in Aotearoa New Zealand each experience poorer mental health than the general population, however no studies have explored the experiences of Autistic trans communities who are likely to be at increased risk of psychological distress. The current thesis explored the mental health experiences of Autistic trans youth in Aotearoa New Zealand using mixed methods. In Study 1, quantitative data from Counting Ourselves, a community-led health survey for trans people, was analysed to describe the mental health of Autistic trans youth (n = 432) and compare this to their allistic trans peers (n = 564). In Study 2, qualitative analysis of interviews with Autistic trans youth (N = 13) was undertaken to facilitate a richer understanding of their mental health and determinants of this. Following a community-based approach to research, the current thesis included community perspectives in the research design, methods, language use, and interpretation of the research. In Study 1, Autistic trans youth were observed to have poor self-rated mental health and life satisfaction, and high rates of loneliness, psychological distress, and suicidality. Both Autistic and allistic trans youth had poor outcomes across measures. It was found that Autistic trans youth had poorer mental health then their allistic trans peers across some measures including self-rated mental health, psychological distress, and lifetime suicidality. These results suggest that Autistic trans youth comprise a group at increased risk of negative mental health experiences. In Study 2, reflexive thematic analysis detailed four themes and 19 subthemes related to the mental health experiences of Autistic trans youth, highlighting determinants of mental health including societal stigma, community connection, family acceptance, self-acceptance, and self- authenticity. The first theme was Identity Journeys, which had four subthemes: Conformity is Detrimental, Identity Self-Awareness Allows Understanding and Acceptance, Benefits of Self- Understanding and Self-Acceptance, and Grief for What Life Could Have Been. This theme described how interviewees underwent a journey through painful conformity experiences toward self-authenticity as they came to awareness and acceptance of being Autistic and trans. The second theme was Finding Acceptance, which had four subthemes: Community Connection is Valuable, Ups and Downs of Acceptance and Rejection, Family Attitudes and Reactions are Important, and Family Should Be a Source of Acceptance. This theme described the importance of acceptance, and how interviewees’ mental health was impacted by others’ reactions toward their identities. The third theme was Societal Stigma, which had eight subthemes: Difficulties Living in Cisgender Neurotypical Society, Harmful Experiences of Hateful Incidents, Continual Expectations of Negativity, Lucky Not to Be Rejected, Masking for Safety and Social Fit, Managing Disclosure of Identities, Societal Misunderstanding of Identities, and Support Systems are Lacking. This theme described the myriad of ways that ableist and transphobic attitudes shaped interviewees’ interactions with society, leading to them feeling unwelcome and expecting to encounter negativity. The last theme was Inner Experiences, which had three subthemes: Identity Links to Mental Health Experiences, Gender Incongruence Distress and Relief, and Communication and Connection Difficulties. This theme described the links interviewees made between their Autistic and trans identities and their internal mental health experiences. Overall, this research indicates that Autistic trans youth in Aotearoa New Zealand face high levels of societal stigma and challenges to their mental health, which contribute to their position as a group at increased risk of negative mental health experiences. The data from this research can be used to inform pathways to better support Autistic trans youth and work toward improving mental health inequities.
  • ItemOpen Access
    The relationship between shame and voice hearing in dissociative identity disorder: a phenomenological exploration
    (2024) Ball, Rebecca Jane
    Through a qualitative phenomenological approach, this study aimed to explore how people with dissociative identity disorder (DID) made sense of their lived experiences of shame in relation to hearing voices (auditory verbal hallucinations). Six participants in treatment for DID at a specialist trauma unit in a psychiatric hospital were interviewed using a semi- structured proforma designed to assess experiences of hearing voices, experiences of the emotion shame, and the relationship between these two variables. Four superordinate themes emerged from the Interpretative Phenomenological Analysis: complex relationship with voices, evolution of shame and voices, voices shame and are shameful, and internal and external retreat. The results of this study were compared with current literature on shame and voice hearing, with many points of similarity found, including with McCarthy-Jones’ (2017) theoretical model of voice hearing. Overall findings suggest that voice hearers have a dynamic relationship with their voices, experience various forms of shame in relation to their voices and in the content of their voices, and respond primarily through avoidance strategies. Aspects of the role of shame in an etiological pathway to voice hearing require further investigation.
  • ItemOpen Access
    Literacy lead teachers’ experiences of a transition to a structured approach to literacy in primary schools across New Zealand
    (2024) Collier, Lisa Anne
    This qualitative research investigated the transition to a structured approach to literacy at primary schools in New Zealand. Six participants took part in semi-structured interviews answering questions around the process, barriers, facilitators and outcomes. The interview transcripts were analysed using reflexive thematic analysis. Six themes were established, with sub themes also detailed. The themes were: Systems failure in literacy | “I’ve ditched the guilt and I’ve handed it over to the government”; Educator driven transformation | “...I’ve gone in, and really gone down the rabbit hole…”; Supporting the transition | “... it’s about influencing”; Workload issues | ‘Juggling all of the plates’ is challenging; Collegial support | “...we’ve fed off each other.”; and Learner success | ‘Empowering’. Participants overwhelmingly spoke about the benefits of implementing this approach, despite experiencing a journey that was challenging at times. The themes were discussed in relation to implementation science frameworks. Practical implications were then listed, to support schools in their journey of transitioning to a structured approach to literacy.
  • ItemOpen Access
    The impact and management of visitor noise on zoo-housed black-capped capuchins (Cebus apella)
    (2024) Herrmann, Kelly
    Zoos provide an opportunity to educate visitors about species and conservation, raise awareness and funding for animals, and facilitate research opportunities. However, the constant presence of visitors at zoos can have a wide range of effects on animal behaviour, which may be used to assess individual welfare. Specifically, zoo visitor noise and activity have been shown to alter animal behaviour negatively. However, few options have been explored to mitigate these effects. Here, I investigated the efficacy of quiet signs at zoos on reducing visitor sound and activity levels at four primate enclosures at Willowbank Wildlife Reserve in Ōtautahi/Christchurch, New Zealand. I found that visitor sound was significantly reduced at three of the four enclosures, and visitor activity level was only reduced at one enclosure. I then measured black-capped capuchin (Cebus apella) behaviour and enclosure use in relation to visitor variables such as noise and activity over time. Ōur results suggest that black-capped capuchin behaviour is highly variable, with alertness, allogrooming, and feeding/foraging/drinking being affected most strongly by visitor characteristics (p-values < 0.05). Autogrooming, locomotion, playing, and resting were not significantly affected by visitors or ecological variables such as weather. We also found variation in behavioural changes between individuals. Although it was not significant, our data showed that the capuchins reduced their distance from the visitor viewing area when there were more visitors (Chapter 3). We found no effect of visitor sound or activity levels on capuchin space use. These findings suggest that visitor sound and activity levels can be reduced using signs to minimise the effect of visitors on capuchin behaviour. When assessing the impact of visitors on zoo-housed animals in the future, more detailed visitor characteristics, such as sound and activity, should be included. More research is needed on the efficacy of quiet signs in zoos and how to maximise their effectiveness.