Science: Theses and Dissertations

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Open Access
Parent experiences and perspectives on children’s cochlear implant processes and support services.
(2023) Jones, Nicholas Ross
Aims: The purpose of this study was to develop a greater understanding of parental experiences and perspectives throughout the paediatric cochlear implant (CI) process and support services in New Zealand. Additionally, the research aimed to identify areas of this process that could be improved in order to support parents to make more informed decisions regarding cochlear implantation in the future. It is hoped the findings will help strengthen, develop and improve the overall paediatric CI process and provision of support services. Methods: A 38-item survey was developed using the Qualtrics™ online software utilising quantitative and qualitative methodology. The development of the survey was based on questionnaires used in research by Bhamjee et al. (2019), Dev et al. (2018) and O’Neill et al. (2004). The anonymous online survey incorporated closed- and open-set questions and was fully completed by 41 parents of children aged 0 to 15 with CIs. Open-set survey responses were thematically analysed by using thematic analysis guidelines developed by Braun and Clarke (2006). Results: The study investigated various aspects related to the paediatric CI process, the challenges the parents faced and the support they received. The survey results suggested that parents are convinced CIs play a critical role in supporting communication, social and educational development. Parents reported their challenges and concerns including fears about the CI surgery, the success of the implant, and the impact it would have on their child’s education and employment prospects. Notable findings were the need for better communication and emotional support for parents throughout the CI process, and also the need for improved collaboration among support services and increased availability of information and resources to help them navigate the paediatric CI process effectively. Conclusion: Parents play a vital role in the CI process, bridging the gap between health professionals and their children. Parental and family involvement have been found to significantly improve speech and language outcomes. Parents in the survey indicated the importance of parental support networks and the value of sharing experiences. The study emphasises the importance of early intervention and access to support services, and the necessity of equipping parents with the knowledge and resources they need, including providing support for their emotional well-being. This will help to ensure the best possible outcomes for children with CIs. By understanding and addressing these parents’ experiences and perspectives of the CI process in New Zealand, it is hoped future parents will be able to make more informed decisions regarding cochlear implantation.
Open Access
The geology of the McDonald downs and Waikari district, North Canterbury
(1949) Schofield, J. C.
Open Access
Eruption sequence and petrogenesis of the Te Onepoto (Taylors Mistake) flank cone system, Lyttelton Volcanic Complex, Te Pātakao- Rākaihautū (Banks Peninsula), Aotearoa-New Zealand.
(2023) Overwater, Geneva Kathleen
Flank cone eruptions on active volcanic complexes often pose a greater hazard to people and infrastructure than eruptions from central vents. The Lyttelton Volcanic Complex (LVC), Te Pātaka-o-Rākaihautū (Banks Peninsula), on the east coast of the Te Wai Pounamu (South Island), Aotearoa, New Zealand erupted from 12.6 – 10.4 Ma through main central cones and dike fed flank cones. The Te Onepoto (Taylors Mistake) flank cone on the LVC, exposed in a 1200 m2 cliff and shore platform within the inter-tidal zone shows extreme facies variability within a small area on the cone. Large clinopyroxenes (<2 cm in size) are inherent to all facies. This thesis adopts a volcanic facies based approach paired with an in depth textural and geochemical analysis of clinopyroxenes across the flank cone facies to track processes occurring throughout the Te Onepoto (Taylors Mistake) flank cone system from the magmatic to the volcanic realm. Detailed field observations provide the foundations of the study for volcanic facies interpretations, revealing five facies and two sub-facies: scoriaceous, strombolian-style pyroclastic fall (scTb facies); phreatomagmatic lapilli-tuff (msT facies); fluidal, hawaiian-strombolian hybrid pyroclastic fall (mmTb facies); hawaiian-style flow-banded lava (fbL facies), which includes a blocky hyaloclastite (bTb sub-facies) and a fluidal peperite (cTb sub-facies); and an intrusive dike (In facies). The eruptive sequence began with an explosive strombolian eruption of due to rapid ascent of a volatile-rich magma with simultaneous phreatomagmatic explosions when seawater entered the vent. A viscous plug developed at the top of the conduit, causing the hawaiian-strombolain hybrid eruptions. An explosive eruption occurred (deposition of cTb sub-facies matrix material), followed by hawaiian-style effusion of flow banded lava. This lava encountered wet-sediment on the flank of the cone and mingled to form the peperite and quenched non-explosively to form the hyaloclastite. Lastly a dike intrusion cut through the flank cone deposits. It is presumed the flank cone erupted in an inter- tidal environment. Petrographic microscopy shows that all flank cone facies display a mineral assemblage of plagioclase, clinopyroxene, olivine and Fe-Ti oxides, with a lower crystallinity for the strombolian facies at the beginning of the sequence (3.6 – 10.4%) and a higher crystalinity from the eruption of the fbL facies onwards (22.7 – 27.4%). Backscattered electron (BSE) images of clinopyroxenes with textures of interest from each facies were generated by scanning electron microscopy (SEM) and selected clinopyroxenes displaying zoning were analysed by electron probe microanalysis (EPMA). Whole-rock compositions were measured by X-ray fluorescence (XRF). Clinopyroxene compositions and geothermobarometers show that the Te Onepoto (Taylors Mistake) clinopyroxenes are all of similar composition (En31.28-46.57Fs8.90-31.33Wo33.31- 46.57) crystallising from genetically similar magmas in the lower crust. Although the clinopyroxenes are compositionally similar, textural analysis determines nine types each associated with varying magmatic processes: type-1 megacrysts and type-2 phenocrysts are anhedral, with mineral and melt inclusions that reflect rapid growth rates across the magma system. Type-3 phenocrysts are euhedral, void of any mineral inclusions and have normally zoned rims, reflecting low-undercooling and entrainment into a more evolved magma. Type-4 phenocrysts are oscillatory zoned and resorbed, reflecting recharge and magma convection. Type-5 groundmass clinopyroxenes are skeletal to subhedral reflecting high to moderate undercooling in the conduit respectively. Type-6 groundmass clinopyroxenes are oscillatory zoned, reflecting moderate undercooling. Type-7 clinopyroxene forms a mantle on olivine groundmass minerals due to recharge. Type-8, clinopyroxenes crystallised from the residual melt in plutonic lithics and type-9, un-zoned clinopyroxenes in plutonic lithics are indicative of cumulate compaction and melt segregation processes. Additionally, a group of Cr-rich clinopyroxenes were identified in the fbL facies which reflect the most primitive clinopyroxenes that were erupted. With the addition of clinopyroxene-whole rock equilibrium relationships and the interpretations of clinopyroxene textures, I present a three-phase petrogenetic model fed by a deep common magma source (perhaps the mantle) for the magma erupted at the Te Onepoto (Taylors Mistake) flank cone. The first phase is cumulate compaction, melt segregation and strombolian to phreatomagmatic eruptions. The second phase follows the same magmatic pathway by recharge, cumulate disintegration and hawaiian eruption of flow banded lava and wet-sediment and water interaction on the cone. The final phase involves magma recharge through a new pathway, convective mixing and intrusion. The origins of clinopyroxenes change from autocrystic in the first stage to antecrystic for the final stages of magmatism and volcanism. This research highlights the capability for magma chamber processes operating within mature alkali-basalt volcanic complexes to diversify the eruptive styles and associated hazards posed by a single flank cone. In addition, it shows that the surrounding environment can alter the eruptive styles to be more explosive and hazardous via lava-water interaction both in the vent and on the flanks of the cone.
Open Access
How therapists conceptualize and communicate treatment boundaries to clients within the therapeutic relationship : a qualitative investigation of current psychotherapy practice.
(2023) Myles, Amy Justine
This qualitative study investigated therapists’ perspectives on treatment boundaries in psychotherapy, what discussions with clients are like and any perceived differences for traumatised clients. Five female clinical psychologists participated in semi-structured interviews and a interpretative phenomenological analysis of the data revealed five superordinate themes: foundations of the therapeutic frame; communication considerations and complex clients; preferences from training and confidence from experience; exploring perspectives with curiosity; sensing the need. Results suggested healthy boundaries create a comfortable frame in which clients can safely explore the reasons therapy was sought and that boundaries are challenged and amended more for traumatised clients due to the perceived need for support being greater. Early training was shown to influence therapists’ understanding of treatment boundaries with confidence in how to articulate them to clients increasing with experience. Implicit over explicit processes were relied on to a greater extent when considering a client’s baseline understanding of interpersonal boundaries. Suggestions for practice are discussed. Mentalisation was used as the theoretical underpinning for this thesis given its foundational stance on effective interpersonal communication and relevance to interpersonal difficulties stemming from childhood trauma.
Open Access
Men in prison for family violence : comparing incident rates for those with violence, sexual, and breach of protection offences.
(2023) Carey, Shontell
There has been limited prior research on men imprisoned for family harm. The goal of the present study was to examine whether family harm offenders differed based on their lead offence type (violence, breach of protection order, and sexual) in terms of their adaptation to incarceration in New Zealand. Specifically, we wanted to see if those with breach of protection orders engaged in more prison incidents and misconducts (and earlier in their sentence) than those with a violence or sexual offence. We also planned to examine if results were similar for Māori and non-Māori. Our sample included men who were incarcerated between 2016 and 2020 for a family harm offence (N = 7,561) and we analysed administrative data provided by Ara Poutama Department of Corrections (COBRA). Men with sexual offences were significantly older, with fewer prior convictions and lower static risk (RoC*RoI), were less likely to be gang members and had longer prison sentences. Men with breach offences had higher static risk and were older than those with violent offences. Survival analyses showed that violent and breach offenders had significantly greater incident rates than sexual offenders, and time to incidents was consistently lowest for breach offenders. Cox regression analyses (which included age, RoC*RoI score, gang affiliation, and previous conviction count as covariates) showed that Māori breach offenders had significantly lower incident rates (all incidents, violent perpetrator, violent victim, and self-harm) compared to Māori violence offenders, whereas incident rates were similar for non-Māori breach and violent offenders. Although time to incidents was shortest for breach offenders, as predicted, the lower incident rates for breach compared to violence offenders for Māori was unexpected and could be investigated in future research. Overall, results of this study show men with breach, violence, or sexual family harm offences differ in their adaptation to incarceration as shown by incident rates, which could help to inform policy for managing these men while in prison.
Open Access
The Pukeko
(1965) Tunnicliffe, Geoffrey Arnold
Open Access
Feeling of knowing accuracy and metamemory functioning in participants with dissociative tendencies.
(2023) Moss, Jordan
The purpose of this study was to explore whether there were significant differences in a non-clinical sample of high and low dissociators regarding their metamemory beliefs and functioning. The satisfaction and ability scales of Multifactorial Memory Questionnaire (MMQ) and the Dissociative Beliefs about Memory Questionnaire (DBMQ) were used to measure metamemory beliefs and Hart’s (1965) Feeling of Knowing (FOK) paradigm was utilised to measure the accuracy of their FOK judgements. The key research objectives were to determine whether 1) higher dissociative tendencies were associated with more negative beliefs around memory, 2) higher dissociative tendencies were linked to more negative FOK appraisals and a tendency to underestimate recognition performance, 3) those with higher dissociative tendencies would have less accurate FOK judgements, and 4) inclusion of trauma/threat related word-pairs would result in more negative FOK judgements and lower FOK accuracy for higher dissociative tendencies. Results found sufficient evidence to suggest a link between dissociation and metamemory functioning was present where there was likely pathological dissociation. While this study did use the inclusion of trauma/threat related word-pairs in its design, there was insufficient evidence to confirm that those with higher tendencies were more likely to make negative FOK appraisals and have lower FOK accuracy when presented with these stimuli. Directions for further research are outlined in discussion.
Open Access
Carbon and nitrogen stocks in soil and biomass in high-nutrient environments.
(2023) Veale, Darryl Andrew
New Zealand native vegetation as well as Pinus radiata are often established in high-nutrient environments adjacent to agricultural land as well as in environments where Treated Municipal Wastewater (TMW) is irrigated onto land. This vegetation has been demonstrated to effectively reduce the negative environmental effects of nutrients and contaminants that would otherwise enter surface and groundwater. However, as yet, there is a lacuna of knowledge on the carbon stocks in and under these vegetation types. Potentially, the aboveground carbon storage in the biomass may be offset by a depletion in soil carbon. This thesis sought to determine the soil carbon stocks under areas adjacent to high nutrient agricultural soil as well as areas receiving TMW. Six sites were selected representing a range of soil orders. Two planted riparian plots, adjacent to critical sources areas and four sites irrigated with TMW were sampled to determine effects of high nutrient farm runoff and high nutrient effluent on soil properties and interaction with above ground biomass. Results from the two areas receiving farm runoff indicated no change in soil carbon irrespective of planted species type or pasture. Above ground biomass stocks were significantly increased in planted areas relative to pasture. Mānuka biomass represented a 20% (24.1 t ha⁻¹) increase in carbon stocks in Lake Waikare and a 23% (12.5 t ha⁻¹) increase in Lake Wairarapa. Mixed vegetation species in Lake Waikare had the most significant net gain in sequestered carbon with a 117% (109 t ha⁻¹) increase compared to pasture. The application of TMW in Duvauchelle at 1000mm yr⁻¹ increased above ground native biomass C stocks by 24% compared to unirrigated control species with no depletion of soil carbon. TMW irrigation at <1,300 mm ha⁻¹ yr⁻¹ in Invercargill had no deleterious effect on soil carbon or significant change on the carbon to nitrogen ratio. TMW application rate of >5,000mm yr⁻¹ resulted in significant (50%) SOC depletion in Levin compared to unirrigated control soils. Establishing vegetation in high nutrient environments results in a net increase in total above and below ground C stocks. Native New Zealand vegetation growth may be accelerated by the application of TMW, however, soil organic matter may be depleted through priming and increased leaching at rates >5,000mm ha⁻¹ yr⁻¹. This may present an opportunity to increase the amount of land where TMW could be applied. Further studies should determine the effect of the effluent on C stocks of mature native forest ecosystems measuring soil C stocks and tree growth over time.
Open Access
Occupational stress, burnout, and resilience in audiologists. Investigating whether resilience is a moderating or a mediating variable between stress and burnout in audiologists
(2023) Karmacharya, Rakshya
Objective: This study aimed to investigate the mediating and moderating role of resilience in the relationship between stress and burnout. The stress factors used in this study included work-life conflict, interprofessional relationships, workload & demands, clinical tasks & protocols, and physical health. Design: A online questionnaire consisting of the Audiology Occupational Stress Questionnaire, the Professional Quality of Life Version 4, the Connor-Davidson Resilience Scale (CD-RISC-10), and a series of demographic variables. Study sample: The sample consisted of 204 audiologists originating from New Zealand, the United States of America, Israel, India, the United Kingdom, Malaysia, South Africa, Australia, Hong Kong, Ireland, Singapore, Canada, and Zimbabwe. Results: The main findings suggest that resilience moderates the relationship between work-life conflict and burnout (p = 0.03) specifically for audiologists who have higher levels of resilience (p = 0.02). A significant negative relationship was found between inter-professional relationships and burnout (r = -0.15, p = 0.02). No other mediating or moderating effects of resilience were observed in the relationship between the other stress factors and burnout. Conclusions: Our study findings suggest that resilience might not act as an overall global buffer however, it does reduce the effect of some workplace stressors such as work-life conflict on burnout. Further research is required to determine the factors that contribute to resilience in audiologists. Likewise, identifying other factors that moderate or mediate the relationship between stress and burnout would help develop interventions that focus on audiologists' health and well-being.
Open Access
Magneto-optical properties of lanthanide doped nanocrystals
(2023) Martin, Jamin Luke Bruce
Lanthanide-doped nanocrystals have attracted considerable interest in recent years due to a plethora of potential applications such as dual-modal detection and therapy of cancer cells, stimulators in optogenetics, energy harvesting elements of solar cells and quantum information processing. While these applications are promising, their use is hindered by a lack of understanding of fundamental physical properties. This thesis focuses on improving the understanding of one such lanthanide doped nanocrystal, KY3F10, through the use of high-resolution infra-red spectroscopy with magnetic fields of up to 4 T, and site-selective laser fluorescence and excitation for both probing the electronic structure and energy transfer dynamics in KY3F10. X-ray diffraction of multiple lanthanide ions doped into KY3F10 is presented (Nd3+, Sm3+, Eu3+, Dy3+, Ho3+, Er3+/Yb3+); it is shown that for lighter ions, the formation of KY3F10 is limited, with even moderate concentrations of Nd3+ quenching the growth process entirely. Site-selective laser fluorescence measurements and crystal-field analysis of KY3F10:Eu3+ are presented and show that the ion resides in a similar environment to the bulk crystal. High-resolution infra-red absorption Zeeman spectra are presented for KY3F10 nanocrystals doped with Nd3+ and Er3+, it is shown magnetic isotropy dictates the presence of observable splittings and that Zeeman splittings are far more sensitive to changes in the magnitude of the crystal-field than the electronic energy levels. A crystal-field fit is also presented using data obtained for KY3F10:Nd3+. In addition to electronic energy levels obtained from absorption and fluorescence, the isotropic magnetic-field splittings are included in the crystal-field. The resulting parameters accurately account for the Zeeman interaction, including non-linear effects and predict isotropic splittings not included in the dataset. A superposition model analysis and sensitivity analysis of the crystal-field parameters indicate structural differences may cause differences in the bulk- and nanocrystals, and that non-superposable interactions play an important role in the determination of the B__ parameter in KY3F10. Additionally, as part of this investigation of Zeeman interactions in nanocrystals, Zeeman infra-red absorption spectra of KY3F10 doped with ytterbium/erbium, dysprosium and holmium were analysed. The use of splittings, particularly in dysprosium doped KY3F10, is discussed for use as a magnetic field sensor. Energy transfer dynamics for KY3F10 nanocrystals doped with samarium are also analysed. Concentration-dependent fluorescence transients indicate energy transfer mechanisms that are dipole-quadrupole in nature. The inferred energy transfer rate is also considerably faster than what is reported in comparable hosts, and an argument based on the crystal structure is presented as a cause. In addition to the work on KY3F10 nanocrystals, lanthanide-doped Y2SiO5 microcrystals, which are of interest as a crystal host in quantum information processing applications were synthesised. These were prepared using the solution combustion, solid state and sol-gel synthesis techniques. Of these, the sol-gel method yields the most reliable and high-quality X2 phase Y2SiO5 microcrystals. Absorption and laser site-selective fluorescence measurements of Nd3+, Eu3+ and Er3+ doped material, performed at cryogenic temperatures, indicate that the as-grown microcrystals are of high optical quality with inhomogeneously broadened optical linewidths that are comparable to bulk crystals at similar dopant concentrations.
Open Access
Evaluation of airway protection using citric acid cough testing.
(2023) Darrock, Keri Louise
In the event of airway invasion, coughing is instigated in attempt to clear the misdirected material. Sensory receptors in the airway identify material that has entered (i.e., aspiration), with disruption to the ability to detect invasion or damage to the communicating pathways resulting in silent aspiration. In the absence of a response to aspiration, individuals are at increased risk of morbidity and mortality. Cough testing enables examination of airway sensitivity by irritating sensory receptors to evoke coughing. Methods of cough testing seek to replicate activation of the receptors in response to aspiration. This research programme aimed to increase the scientific rigour of cough testing by examining factors relating to the administration of the test and interpretation of results. The research programme was guided by a scoping review of the cough testing literature within the field of swallowing. From the review, a methodologic study was developed to enhance our understanding of the effect of citric acid presentation order on cough thresholds. A second study was conducted through use of an online survey to further our understanding on the integration of cough testing results in the clinical management of patients with swallowing disorders. The scoping review explored and documented how cough testing has been used since its translation from the respiratory field into the field of swallowing. The use of cough testing was known to have increased with methodological variability evident across publications. Two independent reviewers completed all aspects of the review. Fifty-seven studies were identified that utilised 59 distinct cough testing protocols. Wide variation in practice was demonstrated across protocols. The review highlighted a need for greater understanding of the implications of different cough testing methods. This is needed to determine the methods that most closely mimic a cough response to aspiration, as well as to prevent inconsistency in the interpretation of results. Further exploration of safety is also required to ensure optimal methods for reducing risk of infection and lung inflammation (bronchoconstriction). Citric acid was identified to be a commonly used aerosol to evoke coughing in protocols. When using multiple strengths (concentrations) of citric acid, they are typically provided in an ascending order (i.e., from low to high concentrations). A major limitation of cough testing is the potential influence of previous exposure to cough evoking aerosols on airway sensitivity, with an attenuation of cough response possible with repeated exposure. Changes in response have been documented across repeated sessions, suggesting that this presentation order does not control for aspects of attenuation to the stimuli. Therefore, the impact of presentation order required exploration, to refine methods of cough testing and determine the instability previously seen in sensitivity thresholds. The first study in this programme of research examined the effect of ascending and descending presentation orders of citric acid on cough thresholds. Healthy participants (n=22) attended two sessions, receiving nine citric acid concentrations in ascending order in one session, and in descending order for the other. No significant differences were identified for natural (NCT) and suppressed (SCT) citric acid cough thresholds or ratings of urge-to-cough (UTC) across conditions. However, the novel design of this study revealed limitations of current methods of testing that have not been shown previously. The results highlight a need to examine the current definition of a cough sensitivity ‘threshold’, before evaluating the impact of presentation order on NCT and SCT in separate sessions. Thus, further investigation is warranted before the finding of stable thresholds across ascending and descending presentation orders can be interpreted with confidence. When used in clinical practice, cough testing is conducted as an adjunct to the clinical swallowing evaluation (CSE), providing information on the integrity of airway sensation and patient risk of silent aspiration. Diet recommendations have been shown to be more restrictive with use of cough testing. However, the specific role played by cough testing results in these decisions remains unclear due to multiple uncontrolled factors in previous research. Therefore, this survey study examined the influence of cough testing results and aspiration pneumonia risk factors on diet recommendations, while controlling for patient characteristics. An online survey was sent to speech and language therapy clinicians working in dysphagia management. Two patient cases were presented that differed only in their presence of risk factors known to be predictive of development of aspiration pneumonia (oral hygiene, smoking status and complexity of medical history). For each patient case there were three assessment scenarios: CSE information only; CSE information plus a ‘pass’ result to cough testing; and CSE information plus a ‘fail’ result to cough testing. Clinicians were required to select one of four diet recommendations for each scenario: baseline diet, modified diet, nil-by-mouth, or ‘other’. Clinicians were also asked to provide their management plans and rationale. Ninety-seven data sets were used in the final analysis. Findings demonstrated that a ‘fail’ result led to the most restrictive recommendations, with less restrictive recommendations given with a ‘pass’ result and when only CSE information is given. Aspiration pneumonia risk factors were shown to influence decision making, with the low-risk patient more likely to be recommended a less restrictive diet. In summary, the scoping review highlighted wide variability in the implementation of cough testing. Also identifying lung function monitoring and methods of solution preparation as key considerations in the administration of cough testing. The results of the methodological study suggest that citric acid presentation order does not affect thresholds, but further studies investigating methodological aspects of cough testing are required before application of this finding can be confirmed with use of specific cough testing protocols. The use of lung function testing alongside cough testing enabled the safety of the protocol to be confirmed but required significant respiratory effort particularly in older participants. Exploration of the interpretation of results revealed that a ‘fail’ cough test result led to more restrictive and cautious patient management. The presence of aspiration pneumonia risk factors also influenced decisions with more restrictive recommendations given for the ‘high-risk’ patient. However, the finding that the patient management decisions made when provided with only CSE information are very similar to patient management decisions made for a ‘pass’ result suggests that patient airway safety is often assumed, despite an absence of information directly relating to risk of silent aspiration. These novel findings require ongoing exploration, with more questions raised around the impact of other methodological choices, and clinicians’ potential assumption of safety in the absence of information around airway sensitivity. Future research should continue to examine questions around the administration and interpretation of cough testing, but there is a need for specific guidance for exploring airway sensitivity in the field of swallowing. Collation of current knowledge would encourage greater consistency in the field, and enable unanswered questions to be highlighted, whilst also ensuring the most appropriate use of methods are used in cough testing to mimic an aspiration event and evaluate silent aspiration risk.
Open Access
Menaquinone biosynthesis in Gram-positive bacteria : probing the conservation of allostery in MenD.
(2023) Klein, Michelle
Menaquinone is a biomolecule involved in various important functions across the kingdoms of life, including acting as the sole electron carrier in the respiratory processes in Gram-positive bacteria. Little is known about the regulatory mechanisms within Gram-positive bacteria that control menaquinone biosynthesis, despite their potential to be utilised in bioengineering to design bacterial strains with increased menaquinone production capabilities or the development of new drugs targeting pathogens. Recently, menaquinone biosynthesis in Mycobacterium tuberculosis and subsequently the Gram-positive bacterium Staphylococcus aureus was identified to be regulated via feedback inhibition. The enzyme 2-succinyl-5-enolpyruvyl-6-hydroxy- 3-cyclohexadiene-1-carboxylate synthase (MenD), which catalyses the first irreversible step in the classical menaquinone synthesis pathway, was discovered to be allosterically inhibited by a downstream product of the pathway: 1,4-dihydroxy-2-naphthoic acid (DHNA). To investigate how conserved this feedback inhibition is amongst Gram-positive bacteria, DHNA inhibition of the MenD from the generally recognised as safe food bacteria Lactococcus lactis and Bacillus subtilis, as well as the pathogen Listeria monocytogenes was studied. The three enzymes were recombinantly expressed and purified, followed by characterisation of their thermal stabilities and enzyme kinetics. They were found to bind to (Kd: 2.6–18.0 μM) and be inhibited by DHNA (IC50: 4.7–12.9 μM). The three MenD were structurally characterised by X-ray crystallography, solving the first structure of MenD from L. lactis, and the first cofactor-bound structure of MenD from L. monocytogenes. The MenD orthologs possess similar tertiary structures and were identified to predominantly exist as tetramers. Attempts to obtain DHNA-bound MenD structures were unsuccessful. However, comparison to the DHNA-bound structure of M. tuberculosis MenD suggests partial preservation of the allosteric DHNA-binding site. Additionally, DHNA was identified to inhibit B. subtilis and L. lactis in their growth, with the growth of B. subtilis rescued by menaquinone-4 supplementation. Together these findings indicate menaquinone biosynthesis via the classical menaquinone pathway could be commonly regulated via feedback inhibition across Gram-positive bacteria.
Open Access
Dysphagia post-stroke : a prospective study on evolution, characterisation and skill-based swallowing training.
(2023) Vallet, Marion Emmanuelle Madeleine Lucile
With reported incidence of 12.2 million people worldwide in 2019, stroke is the world’s second-leading cause of death and the third-leading cause of death and disability combined in the world (Feigin et al., 2021). Among the common disabilities, with a prevalence of 45-65% (Khedr et al., 2021; Martino et al., 2005), oropharyngeal dysphagia has major consequences on quality of life of patients and caregivers, and is associated with substantial costs for the healthcare system. However, little is known about the course of its recovery, and relationships between initial presentation and symptom resolution. Based on increased understanding of the contribution from both the brainstem and supratentorial structures for swallowing initiation and modulation, recent literature has identified distinct patterns of pathophysiological deficits that may involve not only a strength but also a skill component, responsible for impaired motor planning and execution (Ng et al., 2021). These preliminary findings suggest that variability in recovery of swallowing function following stroke may be subserved by pathophysiological deficits specific to lesion site. Moreover, they challenged the historical assumption of weakness being the main deficit underlying dysphagia, and the main treatment target. Following on from previous research from Ng et al. (2021), this research program addresses the gaps in the literature in respect to the relationship between acute presentation and long-term evolution of dysphagia post stroke (DPS), and further investigates the effects of a swallowing skill-based training on swallowing and quality of life in patients with chronic DPS. Study 1 was a prospective, observational study designed in two parts. The first aimed to document the presentation and evolution of dysphagia in the first six months following stroke. The second aimed to characterise swallowing impairments in acute stroke patients according to the pathophysiological mechanisms: submental muscle weakness (strength deficit) or lack of precision in muscle contraction (skill deficit). Further, this study evaluated how dysphagic characterisation predicts long-term outcomes. Sixty consecutive adult participants (mean age 73.3  14.1 [29 – 101], gender ratio [M:F] 1.4:1) were recruited in a tertiary acute hospital at a mean time of 2.8 days  1.5 days after a first-ever acute stroke, following a positive dysphagia screening. Participants were followed longitudinally for six months, with data collected at five timepoints. Sociodemographic and stroke typology data, occurrence of pneumonia, readmission rate and mortality, as well as nutritional data using FOIS and the IDDSI-FDS, were collected during patient interviews or chart reviews. The average length of stay (LoS) in the acute hospital was 7.6  5.6 days. On discharge, 45% of participants were consuming modified diet with IDDSI-FDS 5.9  2.8, and 20% had enteral nutrition. The average length of tube feeding was 16 days. Seventy percent were admitted to a rehabilitation hospital with a mean LoS of 29.1  21.8 days. During the follow up period, 20% of all participants were readmitted, and the rate of pneumonia and mortality was 23% and 8%, respectively. At six months, place of residence was home for 82% and hospital-level care for 13%, while 2% were patients in the rehabilitation hospital. One participant remained fed enterally via gastrostomy (2%) while 11% had a FOIS <7 and IDDSI-FDS<8, reflecting some level of modified intake. Six percent (n=3) of participants were still undergoing dysphagia management by a speech- language therapist, one participant for active rehabilitation, two for texture management. Multivariate analyses were conducted to identify prognostic factors for poor clinical outcomes at discharge and at six months. Patients with more severe stroke (NIHSS on admission) were more likely to be discharged to rehabilitation hospital. No other variables of interest were identified to predict the occurrence of pneumonia, mortality, readmission, residence, or diet level. Twenty-two participants of the sample consented to be further evaluated to characterise dysphagia. A cranial nerve assessment, objective tests of functional oral intake (TOMASS and TWST), and a self-assessment of swallowing-related quality of life (SWAL-QOL) were completed. Muscle strength and contraction accuracy components of the suprahyoid muscles were assessed using surface electromyography (sEMG) coupled with a biofeedback device (BiSSkiT) during saliva swallowing and jaw opening tasks. Each SWAL-QOL parameter was significantly influenced by stroke laterality and swallowing temporal errors. After six months, TOMASS scores were within the range of normal for 32% of participants and 15% for the TWST. Mixed effect models revealed that TOMASS number of swallows increased significantly between three and six months (+0.61, p=0.03). Using multiple linear regression analysis, significant influence of stroke site on TOMASS number of swallows (p=0.02) and TWST swallowing capacity (p=0.04) were found. A significant influence of swallowing temporal (p=0.04) and amplitude (p=0.002) errors were also found on TWST ingestion time. The results of mixed effect models analysis revealed a significant effect of time point on the sEMG variables. Specifically, effortful hit rate increased significantly between 10 days and one month (p=0.04), swallowing temporal error and hit rate from admission to six months (p<0.01), and jaw opening hit rate between three and six months and from admission to six months (p=0.04). Right strokes were significant predictors of decreased swallowing precision (hit rate) (p=0.03). Subcortical involvement was a significant predictor of decreased jaw opening precision (temporal errors) compared to cortical strokes (p=0.005). The second part of this research program (Study 2) was an exploratory, interventional study investigating the effectiveness of a swallowing skill-based training on swallowing and quality of life for individuals with persistent dysphagia in the chronic stage of recovery, six months post stroke. Designed as a case series on an A-B-A design, the protocol included two baseline measures across two weeks, followed by a two-week treatment period, and two follow-up periods (two weeks and two months apart, respectively). Participants who completed the first study were eligible if they presented persistent dysphagia six months after their stroke. Of a possible 13 participants, four consented to participate and were recruited. During the two-week treatment period, one-hour daily sessions involved a swallowing skill-based training protocol, using sEMG paired with biofeedback. Clinical and swallowing outcome measures included patient’s reported dysphagia (EAT-10) and quality of life (SWAL-QOL). The TOMASS and TWST provided clinical measures of ingestive swallowing of solids and fluids, respectively, and a cranial nerve examination was completed, along with physiological swallowing measures of strength and skill derived from the sEMG device coupled with the BiSSkiT software. Additional measures were collected to inform on swallowing biomechanics using videofluoroscopy (hyoid excursion, pharyngeal residue ratio [PRR], penetration- aspiration scale [PAS], duration of laryngeal vestibule closure [LVC] and upper oesophageal segment [UES] opening) and durational parameters using sEMG (premotor time [PMT], preswallow time [PST], total duration of contraction [TDC]). Descriptive statistics showed increased SWAL-QOL scores following treatment for all participants. Although they all demonstrated some level of functional improvement based on clinical outcomes (TOMASS, TWST, sEMG temporal measures of PMT, PST and TDC), the results were inconclusive in the absence of distinct patterns of change. In terms of strength and skill measures, swallowing temporal precision improved in half of the participants, and swallowing amplitude in all of them; jaw-opening temporal precision improved for one third and amplitude in one half of participants. With respect to VFSS, only one participant was able to undergo the assessment, and results were reported descriptively. This study offers a preliminary and novel step in exploring the nature and evolution of strength and skill deficits underlying dysphagia. It suggests that distinct pathophysiological deficits of swallowing strength and skill may be influenced by stroke characteristics. It also provides preliminary evidence that swallowing temporal error may influence functional water swallowing and quality of life, suggesting that pathophysiological mechanisms of strength and skill may influence functional recovery of swallowing following a stroke. These findings support the need for development of differential diagnostic tools to better identify patients at risk of developing chronic dysphagia based on their pathophysiological deficits. They also provide reason enough to further explore these pathophysiological mechanisms with studies on larger samples to develop targeted rehabilitation approaches. This should greatly improve the effectiveness of our interventions by producing long- term effects on swallowing and thus on the quality of life of individuals following a stroke.
Open Access
The Gibbston slide, Kawarau Valley, Central Otago
(1986) Johnson, James Douglas
The Gibbston Slide is a large, complex, deepseated dip slope failure in highly anisotropic schist. An investigation to assess the impact that the formation of a 30m deep reservoir across the toe would have on the stability of the slide mass has been undertaken. Field investigations, including detailed geological and geomorphological mapping, supplemented by some drillhole and surface monitoring information, allowed zoning of the slide mass in terms of its surface and subsurface characteristics. This has enabled the development of a failure model. A comprehensive test programme was undertaken, using a ring shear apparatus which was able to be both stress controlled and strain controlled, to investigate the response of various engineering soils within the slide mass to changes in strain rate, shear stress and effective normal stress. Aspects of stick-slip behaviour have also been investigated. As a result of this research programme a method for predicting the performance of an existing slope failure has been developed.
Open Access
A comparative study of personality patterns of Maori and pakeha children as revealed by the Rorschach technique
(1951) Malcolm, Yvonne
Open Access
Assessment of risk on the Kepler Track, Fiordland.
(2002) Ferrick, Bree
With the increase in use of New Zealand's mountain terrain there is a growing need to identify and manage the hazards that exist. This study investigates the potential for integrated risk assessment to be undertaken in remote mountainous environments using methods of aerial photo and contour map interpretation, field studies, climate data analysis and GIS on the Kepler Track, Fiordland. The study presents an opportunity to gauge the applicability of GIS in remote regions relatively devoid of empirical data. Fieldwork and analysis of previous research identified three main forms of hazard on the Kepler; that of avalanche, landslide and exposure. The study identified fourteen avalanche paths in the alpine traverse of Mt Luxmore, characterised by steep, gully type starting zones and N-NW aspects. The estimated recurrence interval of avalanching is 0.3-Syrs. Six zones of exposure were mapped on N-NW aspects and exposed ridgelines. These have the greatest estimated frequency of up to 15 times per year. Potential landslide failure zones were delineated using GIS. The identified 33 zones were characterised by steep slopes along drainage channels and by frequency of landsliding estimated at l.6yr⁻¹ in summer and 0.7yr⁻¹ in winter. Using the estimated frequencies a risk index of overall risk for the individual hazards was developed. The risk index identified the variation in risk level with season, the greatest risk being from exposure. GIS then provided a means to assess and integrate risk to create risk maps for the track in both winter and summer seasons. The management implications of these findings are outlined. There is potential for GIS to be employed in risk assessment of remote alpine areas and although the application of GIS was limited in this study, it now provides a basis on which to assess the use of GIS in delineation of hazard zones from future events.
Open Access
Lanthanide-doped potassium yttrium fluoride nanoparticles : spectroscopy, thermometry and crystal field analyses.
(2022) Solanki, Pratik Singh
Mixed metal fluoride nanoparticles of the MYF family (M=Na, K, and Ba) are an excellent choice as the host for lanthanide-doped upconverting nanomaterials since they are able to accommodate rare earth ions at the Y³⁺ sites. Moreover, these fluoride materials have relatively low phonon energies, thereby minimising non-radiative relaxation, ensuring good fluorescence quantum efficiencies for the principal emitting levels. However, despite many studies, reports on the corresponding fluoride nanomaterials are minimal, describing the detailed optical properties such as the effect of optimum pump wavelength on optical properties and the excited-state dynamics for lanthanide-doped nanoparticles, low-temperature optical spectroscopy, which is crucial in order to enhance their optical performance for further technological applications. Therefore, the work of this thesis is dedicated to understanding and tackling these challenges with mixed metal fluoride nanoparticles based on the KYF family. In the first experimental studies, we investigated the effect of infrared laser excitation wavelength and core@shell nanoarchitectures on up-conversion fluorescence and luminescence thermometry of Yb³⁺/Er³⁺ co-doped KY₃F₁₀ upconverting nanoparticles. High-resolution Yb³⁺ excitation spectra were measured by monitoring the Er³⁺ ⁴S₃/₂→⁴I₁₅/₂, ⁴F₉/₂→⁴I₁₅/₂ upconversion fluorescence, with the highest fluorescence yield obtained at 10254 cm⁻¹ (975 nm) for both core and core-shell nanoparticles. We observed a five-fold increment in Er³⁺ upconversion intensity using resonant excitation compared to excitation at 980 nm for both nanoparticles. The maximum thermal sensitivity of 1.51 %·K⁻¹ (300 K) and temperature uncertainty of 0.113 K for KY₃F₁₀:Yb³⁺/Er³⁺ core nanoparticles were achieved by tuning the excitation wavelength to 975 nm in resonance with optical transitions of the Yb³⁺ ion. It was found that core@shell nanoarchitectures and laser excitation wavelength had no evident influence on thermometric performance except enhancement in the upconversion emission intensity. Secondly, we studied upconversion fluorescence and colour tunability properties of Er³⁺/Yb³⁺ codoped β−KYF₄ and β−NaYF₄ nanoparticles by tuning the laser excitation wavelength. The Yb³⁺ ²F₇/₂→²F₅/₂ absorption spectra exhibit absorption maxima at 10237 cm⁻¹ (977 nm) for β−NaYF₄ and 10267 cm⁻¹ (974 nm) for β−KYF₄ nanoparticles. The Er³⁺ upconversion fluorescence spectra consist of the ²H₁₁/₂, ⁴S₃/₂, and ⁴F₉/₂→⁴I₁₅/₂ transitions for either 974, 977 or 980 nm laser excitation in both materials. We observed an enhancement in the upconversion intensity by a factor of up to 20 for β−KYF₄ and 1.5 fold for β−NaYF₄ under resonant excitation compared with off-resonant excitation at 980 nm. The CIE chromaticity coordinates of β−KYF₄ nanoparticles are (0.6836, 0.3151) with a highest red colour purity of 99.70% (centred at 617 nm) along with colour coordinate temperature (CCT) value (4700 K) were in good agreement to coordinate of National Television System Committee (NTSC). The absolute upconversion quantum yields are 1.18% and 2.34% under low power density (1.65 W.cm⁻²). Furthermore, we explored phase-dependent fluorescence and thermometry properties of cubic (α) and hexagonal (β) phases of KYF₄:Yb/Er upconverting nanoparticles. The Yb³⁺ absorption spectra of these two nanoparticles exhibit similar absorption maxima at 10268 cm⁻¹ (974 nm). The green and red fluorescence of the hexagonal phase (β) was around 100 and 2000 times more intense than that of the cubic (α) phase of KYF₄:Yb/Er nanoparticles. The red to green ratio (R/G) was 50:1 and 2:1 for the β−KYF₄:Yb/Er and α−KYF₄:Yb/Er nanoparticles. Using the FIR technique from the thermally coupled ²H₁₁/₂ and ⁴S₃/₂ levels, a very high thermal sensitivity of 2.039 and 1.655 %·K⁻¹ at physiological temperature was achieved for α−KYF₄:Yb/Er and β−KYF₄:Yb/Er nanoparticles. In addition, the high sensitivity of α− KYF₄:Yb/Er can be explained using the classical Judd-Ofelt (J-O) theory. Finally, high-resolution spectroscopy and a crystal field analysis was conducted for KY₃F₁₀: Er³⁺ nanoparticles and K₂YF₅: Er³⁺ microparticles. A total of 49 crystal-field energy levels, distributed amongst 13 multiplets of the Er³⁺ ion, have been deduced for the C₄ᵥ point group symmetry site of the Er³⁺ ion-doped KY₃F₁₀ nanoparticles. A parametrised, single-electron crystal-field calculation provides an excellent approximation to the experimental data with optimised crystal fit parameters that are comparable to the bulk KY3F10:Er³⁺ crystal. Simulated spectra, based upon wave-functions derived from the crystal-field calculations, unequivocally demonstrate that excited state absorption is the predominant upconversion mechanism in this material– agreeing well with upconversion excitation spectra obtained for Yb³⁺ co-doped samples. Similarly, we constructed an energy level scheme for 39 crystal-field states amongst 7 multiplets of the Er³⁺+ ion, which have been deduced for the C2v point group symmetry site of Er³⁺ ion doped K₂YF₅ microparticles. Furthermore, a comprehensive crystal-field model for Er³⁺ ion doped K₂YF₅ microparticles through the use of experimental energy levels was deduced from absorption and fluorescence spectroscopy.
Open Access
Social behaviour in early childhood : the role of inhibitory control and normative beliefs.
(2023) Breen, Rose Charlotte Athena
This study examined the effects of inhibitory control and normative beliefs about aggression and prosocial behaviour on aggression and prosocial behaviour in early childhood (ages 2-5). The extent to which normative beliefs about aggression moderated the relationship between inhibitory control and aggression was also explored. As part of a larger study, children (63) from three different preschools in Christchurch New Zealand completed computer-administrated tasks measuring inhibitory control. Beliefs about aggression were assessed using vignettes enacted with either toy figures or computer animated videos where children were encouraged to respond to each enacted scenario. A teacher rated measure was used to assess children’s aggression and prosocial behaviour. Inhibitory control was significantly associated with reactive physical aggression while normative beliefs about aggression was significantly associated with proactive physical aggression. Age was also found to have significant associations with inhibitory control and normative belief factors. No significant moderating relationship was found between inhibitory control, normative beliefs about aggression and aggression. This study highlights the differential associations of factors associated with aggression.
Open Access
The utility of PERMA wellbeing elements to predict sleep quality, nutrition, and bedtime procrastination among university students.
(2023) Lionnet, Shauna
University students are a ‘high risk’ population in terms of adverse outcomes, often reporting poor sleep quality, poor wellbeing, and poor nutrition; all of which are crucial to establishment and maintenance of good mental and physical health and positive academic outcomes. Additionally, university students tend to experience moderate bedtime procrastination; a behaviour linked to increased risk of depression, anxiety, and stress. The overarching aim of the current study was to examine the PERMA wellbeing predictors of sleep, nutrition, and bedtime procrastination in first-year psychology students. To address this, 327 first-year Psychology students from the University of Canterbury completed a battery of questionnaires administered via an online survey to assess their sleep quality, nutrition, bedtime procrastination, and wellbeing. Results indicated that participants had high rates of poor sleep quality, poor nutrition, moderate bedtime procrastination, and relatively good wellbeing. In terms of wellbeing predictors, sleep quality was predicted by positive emotion, nutrition was predicted by accomplishment, and bedtime procrastination was found to be predicted by engagement. These results provide novel findings and support for, as well as expansion of, existing research in the fields of wellbeing, sleep, nutrition, and bedtime procrastination. The current study contributes further to our understanding of these relationships in addition to informing targeted interventions that may lead to improved sleep quality, bedtime procrastination, nutrition, and wellbeing outcomes for university students.
Unknown
Standing in both worlds : exploring hapū-led biosecurity management at Whareponga.
(2023) Gibson, Jade
Initially, my research set out to investigate the role of marae and hapū in managing biosecurity threats, such as myrtle rust and pest species, within their rohe. However, as I progressed my focus shifted from examining their practices to exploring my own whakapapa and the extent of my responsibility in supporting marae, hapū and iwi in managing biosecurity threats on whenua Māori. Using my personal experience, I explore how kaupapa Māori research can be conducted to support biosecurity management at a marae/hapū level. Through my own journey and reflections, this research provides valuable insights for those interested in conducting environmental kaupapa Māori research at a marae-hapū level. Through determining why biosecurity is important to the whānau and working with them to explore management practices that may reduce the impact caused by myrtle rust and pest species at Whareponga, I uncover a process through which kaupapa Māori research can be conducted with a biosecurity lens. This research provides a template for other researchers, consultants, government authorities, whānau, and any individuals who have a desire to work alongside Māori, and to do so meaningfully.