Science: Theses and Dissertations

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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.
Open Access
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.
Open Access
Spatial and temporal distribution of foraminifera in Te Whakaraupō/Lyttelton Harbour.
(2023) Doyle, Olivia
Foraminiferal assemblages can be used to interpret the depositional environment and age of past sediments, and track changes in modern sediments. This study investigated the spatial distribution of foraminifera across the intertidal sediments in Te Whakaraup􀇀/Lyttelton Harbour to determine what species and assemblages were associated with certain environmental parameters. This research also sampled the foraminifera at two locations across a calendar year with the aim of tracking the life cycles of Ammonia aoteana and Trochammina inflata. Surface samples for the spatial distribution study were collected across seven locations in the harbour, with samples from across the tidal profile (MHWS through to MLW) collected at each where possible. The foraminifera from each station were counted and grouped into four clusters based on the relative species abundance, using a Bray-Curtis Q-mode analysis. The environmental parameters from each station (grain size distribution, organic matter content, and tidal elevation were the primary factors considered) were matched to each cluster. A higher proportion (>4%) of organic matter led to Textulariida species, with the tidal elevation determining whether Entzia macrescens or T. inflata dominated. In areas with less organic matter, the dominant sediment grain size determined the prevalence of Ammonia aoteana, with the species preferring a sandier sediment over silt. To determine the life spans and cycles of T. inflata and A. aoteana, samples were collected each calendar month. Four replicates were taken as well as a sample for sediment analysis, of a surface sample and one from 9-10cm depth. No samples had sufficiently high proportions of living foraminifera to calculate life spans. The fluctuations of density and relative proportions of the both species were used to interpret potential blooms. Changes in A. aoteana appeared to be due to changes in temperature, but changes in T. inflata could not be clearly linked to a single environmental change. Due to patchiness between replicates, with significant variation in total abundance of foraminifera, fluctuations in density were not always sufficient evidence of variation. However despite density changes between replicates, relative abundance stayed similar between them. This supports continued use of relative abundance of foraminifera for studies when replication is not present, but cautions the use of interpretations drawn from total foraminiferal abundance if replicates are not used.
Open Access
Detection of cloud phase using ceilometer observations in New Zealand and the Southern Ocean.
(2023) Whitehead, Luke
Supercooled liquid water (SLW) clouds are commonly observed in the Southern Hemisphere but are poorly represented in current climate models. Due to signal attenuation, satellite borne lidar observations of SLW are biased, so surface-based measurements are needed for understanding the distribution of SLW cloud for the purposes of model evaluation. The use of depolarization lidar to measure atmospheric volume depolarization ratio (VDR) is a common technique in classifying cloud phase (liquid or ice). Unfortunately, such lidars are uncommon and not suited to remote and extended measurement campaigns. This thesis is focused on identifying whether ceilometers (simple, low-power lidars) can be utilized to quantify SLW occurrence over the Southern Hemisphere, particularly the Southern Ocean. Previous work has established a technique to detect supercooled liquid water containing clouds (SLCC) from ceilometer retrievals, using a supervised machine learning model. Utilizing a depolarization lidar training dataset from Davis Station, Antarctica, that study trained an eXtreme Gradient Boosting (XGBoost) model on a set of copolarized attenuated backscatter peak properties. However, no warm liquid water clouds (WLCC) were present in the Antarctic training dataset, limiting the transferability of that model (hereafter named G22-Davis) to other regions where WLCC is present. In this study, we apply and evaluate G22-Davis on a 9-month Micro Pulse Lidar (MPL) dataset collected in Christchurch, New Zealand, a mid-latitude site. After building a reference VDR cloud phase mask, we found that G22-Davis performed relatively poorly at SLCC detection with an accuracy of 0.62. Unsurprisingly, G22-Davis often misclassified WLCC as SLCC. We then trained a new model, G22-Christchurch, to perform SLCC detection on the same set of co-polarized attenuated backscatter peak properties. G22-Christchurch performed well, with accuracy scores as high as 0.89. To interpret the model results, we analysed feature importance scores and found that using only peak temperature, width and prominence (defined as the difference between the peak height and the surrounding baseline) as inputs, our model could perform equally well as the original model. Additionally, further instrument deployments were carried out in Invercargill, New Zealand and on the RV Tangaroa Antarctic voyage to make detailed measurements of cloud occurrence in and around the Southern Ocean. These lidar and ceilometer datasets will be useful in future work to study SLW cloud occurrence in the Southern Hemisphere.
Open Access
Modelling wilding pine spread.
(2023) Hughes, Elliott
Invasive pines pose a threat to biodiversity in New Zealand, but our understanding of the dynamics of invasions and the factors that retard or accelerate spread is limited. We consider the past models of wilding pine spread and develop a new model of pine invasion. We show that many prior models feature parameter estimates which are not biologically supported and rely on a conjecture to obtain an asymptotic spread speed of invasive pine populations, the main output of these models. Our new approach uses partial differential equations to model an invasion, as opposed to past integrodifference matrix equation or cellular automa models. We show that invasions are almost static for a significant period of time before rapidly accelerating to spread at a constant rate. Furthermore we show that this lag is robust to spatial heterogeneity in parameters such as growth rates, carrying capacities, or tree fecundities. Our work suggests that prior methods for estimating invasion speeds may not accurately predict spread and are sensitive to assumptions about the distribution of parameters. However, we present alternatives and suggest directions for further research.
Open Access
Initiation and mechanisms of rock slope failures during the 2016 Mw 7.8 Kaikōura earthquake, New Zealand.
(2023) Singeisen, Corinne Sibylle
Earthquake-induced landslides are among the most consequential secondary hazards of large earthquakes. In recent years, numerous fatalities and large economic loss resulted from coseismic landslides triggered by the 2008 Wenchuan earthquake in China and the 2015 Gorkha earthquake in Nepal. In order to improve the management of hazard and risk from coseismic landslides in the future, it is crucial to develop an in-depth understanding of the factors controlling their initiation and failure mechanisms. The 2016 Mw 7.8 Kaikōura earthquake triggered thousands of landslides across varying topography, geology, and fault domains. Investigations of landslides triggered by this well-documented event can thus reveal valuable insights into the controls on coseismic landslide initiation and failure mechanisms. multi-method site characterisation including 3D pixel tracking in pre- and post earthquake aerial imagery, geomorphic mapping, rock mass characterisation, geophysical ground investigations and a geotechnical borehole, I developed engineering geological ground models for selected individual sites in Lower Cretaceous Torlesse greywacke and Neogene siltstone. Analysis of a landslide in Neogene massive siltstone illustrates the role of high persistence bedding planes in generating large translational rockslides, while failures in Torlesse greywacke rock mass, with its closely spaced but low-persistence joints, do not appear to follow traditional failure mechanism models. Based on engineering geological ground models, I developed a conceptual framework of coseismic failure in Torlesse greywacke and proposed a ‘joint-step-path’ failure mechanism in which rupture surface propagation occurs along pre-existing, but low-persistence joints through multiple degrees of kinematic freedom. This mechanism appears to control the failure evolution in three main stages - incipient, transitional and rock avalanching - regardless of the tectonic domain and site-specific dominant discontinuity sets that might affect the extent and style of deformation. Hazard increases for a hillslope when it transitions from the metastable stage to incipient failure and avalanching. To quantify these transitions between failure stages, I analysed coseismic displacement and strain for six landslides in Torlesse greywacke rock mass. This information could potentially serve as a useful tool because many coseismic regional-scale pseudo-physics-based susceptibility models require some displacement threshold above which the slope is assumed to transition into a landslide. For slopes at the incipient and transitional stage, 1D maximum total strain appears to be closely correlated with source area slope angle. Based on these results, I develop the ‘transitional slope strain index’ (TSSI) that combines 1D maximum total strain with source slope angle. Although the predictiveness of TSSI is currently limited due to the number of sites included for its derivation, with the addition of more observational data, TSSI could serve as a useful tool for assessing the likelihood that a slope will transition into a more mobile, and therefore more hazardous, rock avalanche. Dynamic numerical back-analysis of the initiation of two landslides in Torlesse greywacke was used to investigate and test hypotheses based on field and remote sensing observations. The results confirmed that landslide susceptibility in Torlesse greywacke is strongly influenced by slope angle, rock mass jointing and joint strength and that the joint-step-path failure mode is controlling displacement in these slopes. The results also showed that coseismic failure initiation is strongly dependent on the amplitude and duration of the ground motion used as the input for the simulations. The mechanism of failures can be reproduced using a random Voronoi joint network and adopting residual joint strength parameters. Overall, the model results lend weight to the joint-step-path failure mechanism hypothesis. This thesis highlights the role of failure mechanism in coseismic landslide hazard and risk and contributes to an in-depth understanding of physical processes leading to failure initiation. Notable outcomes include the new ‘joint-step-path’ failure mechanism for highly jointed rock masses such as Torlesse greywacke and the ‘transitional slope strain index’ TSSI that links permanent slope deformation to the likelihood of rock avalanche failure. Such incremental improvements in the understanding of coseismic landslide hazard, based on detailed multimethod site investigations, can help to inform regional forecasting efforts and, ultimately, improve resilience to coseismic landslides in New Zealand and abroad.
Open Access
The transition between sand and mixed sand and gravel beaches in northern Pegasus Bay
(2000) Pescini, Jacob Mark
This thesis examines the morphosedimentary characteristics of a transition between sand and mixed sand and gravel beaches in northern Pegasus Bay. Northern Pegasus Bay is situated on the central east coast of the South Island of New Zealand, and is distinctive because it contains both sand and mixed sand and gravel beaches. For two thirds of its length, Pegasus Bay is composed of sand sizes sediments. In the northern third of Pegasus Bay the beach sediments are composed of a mixture of sands and gravels. Sand and mixed sand and gravel beaches have been described in the literature as exhibiting vastly different morphologies, primarily due to the sizes of sediment forming these beaches. While mixed sand and gravel beaches are rare on a world scale, they are a common occurrence along the east coast of New Zealand. This thesis examines the morphological and sedimentological transition between these two beach types. Description of the sedimentary transition was based on 34 foreshore sediment samples at 9 locations over a length of 13.4km. Morphological differences were examined through beach profiling of the same nine locations and examination of previous beach profiles within the study area. The sediment analysis revealed that the sedimentological transition results from the interaction of the amount of sand supplied from the Ashley River and the size of the gravels within the mixed sand and gravel sediments supplied from the Kawai and Waipara rivers. The interaction between the sediments is the primary control on the morphology of the beaches, which exhibit a marked variation along the coastline. The control of the varying sediment populations was identified as being especially pronounced following storms in Pegasus Bay, where the beaches show marked differences in their responses to such events.
Open Access
The coastal morphology and processes of Rarotonga, Cook Islands
(1993) Watkins, Jackson Jason Gregory
This thesis investigates the coastal morphology and processes of Rarotonga, Cook Islands. Field research was undertaken in Rarotonga, between January and April 1993. This investigation was conducted at differing spatial scales and levels of Intensity. In order to obtain a wide understanding of the coastal environment of Rarotonga, two phases of inter-related field research were conducted. The first phase circumnavigated the coast of Rarotonga, conducting general observations and measurements of .a series of beach parameters including slope, width and sediment characteristics, and lagoon parameters including water depth, width of the reef flat and sediment characteristics. These general observations led to the development of three classification systems for the coastal environment of Rarotonga that categorise different beaches based on the various coastal parameters observed. The second phase of field research was undertaken at two sites that exhibit different beach and lagoon morphologies. The characteristics of breaking waves, waves that have reformed on the reef flat and waves that break on the shore were observed. Recordings of water levels and current velocities were undertaken on the reef flat in an attempt to establish any relationships that exists between wave action on the reef crest and process characteristics on the reef flat. Results indicate that beach and lagoon morphology and sediment characteristics are spatially diverse around the coast of Rarotonga. Processes of water circulation within the lagoons are highly variable and complex due to the generation of 'alternative' current flows which interact with the dominant flows, causing irregularities in circulation. The alternative currents result from the interaction of a number of processes, primarily variations in lagoon geometry, wave and wind characteristics and orientation of reef structure. The nature and magnitude of coastal processes differ considerably around the island, due to variability in the modification of waves by the reef structure. Low energy processes experienced at the study areas are not the'· dominant processes of beach and lagoon development, instead more infrequent high energy events are thought to be responsible.
Open Access
Geomorphic evolution of the South Bay coast, Kaikoura
(2002) Boorer, Suzanne Marie
This thesis examines the development of the beach and coastal hinterland of South Bay, Kaikoura. This beach is a mixed sand and gravel system that has a history of progradation, an unusual feature of such a beach type. Research on the northern and southern bays of the Kaikoura coast by McLean (1970) described highly unusual longshore sediment patterns based on the sediment textural properties of the beach (variation series). The sequence in the northern bay was later analysed by Dawe (1997) who coupled sedimentary studies with a study of the geomorphology of the area to describe the Late Quaternary development of the northern part of the Kaikoura coastal plain. My research examines and explores the variation series of South Bay and links the sequences in the two bays. The sequences are shown to be similar and complementary in that one of three rivers (the Kowhai River), that are the principal sources of beach sediments has 'switched' back and forth between the two bays from time to time. Beach sediments in South Bay were sampled and analysed in order to provide further detail about the variation series originally described by McLean (1970). A distinctive sequence of beach ridges and an associated coastal lagoon has been described from fieldwork, air photo interpretation and mapping. Three explanations of how the coastline and lagoon may have developed are presented and it is noted that further research dating the sequence is required in order to clarify the chronological and geomorphologic development.
Open Access
Post-earthquake beach response, Napier, New Zealand
(1985) Single, Martin Bernard
The study concerns the effects of tectonic changes to mixed sand and gravel beaches. Many of the beaches in New Zealand subjected to increasing pressures of human usage, are of this beach type and have an active tectonic history. The Napier beaches have been examined to establish the changes caused by the Hawke's Bay earthquake of 1931. The interaction between the base level change and the beach changes were examined to determine the degree to which the present beach morphology is a response to the tectonic vertical displacement. The evidence of coastal change in Napier before and after the 1931 earthquake was examined to define the morphological characteristics of the pre-earthquake beaches. A model of the response was then derived from an analysis of the difference between the present beaches and the pre-earthquake ones. This information was used in the derivation of a general model for estimating mixed sand and gravel beach profile response to tectonic uplift. Post-earthquake changes will occur in two stages. Primarily the beach will be uplifted, translating the shoreline seawards to a distance dependent on the amount of uplift and the shape of the nearshore profile. The second stage of the post-earthquake change will be as a response to the adjustment. The beach will erode until the pre-earthquake form is re-established.
Open Access
The interaction of inversion development and katabatic winds : implications for air pollution in Christchurch
(2000) Johnstone, Samuel James
This thesis aims to assess the role and interaction of stability and katabatic flows in Christchurch's air pollution problem. The determination of the spatial and temporal characteristics of inversion development and katabatic winds, how they interact in the stable boundary layer and their implications for air pollution in Christchurch is the prime focus. An extensive meteorological monitoring network was established in and around Christchurch to achieve these aims. This included surface based stations and towers located at Jade Stadium and Greers Road. The field study of this research contributed to the Christchurch Air Pollution Study (CAPS), involving the University of Canterbury, NIWA, Environment Canterbury, Landcare Research, University of Auckland and Karlsruhe University, in which air pollution monitoring and vertical profiling, were carried out during July. The dataset used for this thesis includes surface . and tower measurements, tethered balloon profiles, SODAR and ambient pollution concentrations over the winter of 2000 with special observation nights during the month of July. The monitoring campaign was a success despite meteorological conditions during the winter study period not being typical, with the warmest July on record occurring. Of the meteorological conditions found to govern pollution events in Christchurch, the correlations between air pollution and stability and airflow the most significant. Large temporal and spatial variations were found in the inversion strength in the lower atmosphere around Christchurch, which can be related to the land use of the area, with the height of the urban canopy and sky view factor the main contributing elements. The application of a 'wind vector model' (enclosed on disc) and stability wind roses identifies the complex nature of the wind field and occurrence ofkatabatic winds during high pollution nights. The following phenomena are also discussed; the interaction between katabatic winds originating from the Port Hills and Canterbury Plains; the effect of windspeed within the flow and impact of advection on the lower atmosphere. A variety of methods were used in the analysis, including isochrone maps, vertical profiles and a RAMS model simulation. Case studies of these phenomena demonstrate the significant impact katabatic winds have on the lower atmosphere over Christchurch, generally increasing the inversion strength and hence further limiting air pollution dispersion. It is vital that the processes involved in creating Christchurch's air pollution problem, are accurately documented and understood, to ensure that appropriate air quality management techniques are used by the local environmental authorities. In this regard, this research has aimed to help improve the understanding of the processes involved and how they interact in creating Christchurch's air pollution problem.
Open Access
Surfactant Bioreporters : investigating bacterial viscosin expression in response to protozoan predation.
(2023) Kear, Evan
The coincidental evolution theory proposes that the selective force of predation may result in the emergence of pathogens, as organisms gain increasingly antagonistic characteristics which may also act as virulence factors in an alternative environment. The primary interaction between amoeba and bacteria is one of predation, with amoeba being found coexisting with bacteria in almost every environment. It has previously been stipulated that this interaction provides a ‘training ground’ for emergent pathogens. Thus, the interaction between bacteria and amoeba is of high interest. A coevolved Pseudomonas fluorescens SBW25 strain named ‘Volcano’ expresses the genes for the potent biosurfactant viscosin at higher rates in the presence of Acanthamoeba and displays greater resistance to predation. The tools typically used to investigate such interactions are limited in their resolution, averaging the expression metric for large amounts of biomass. However, cellular expression is expected to be heterogeneous throughout a population due to factors such as microenvironment, non-clonality of cells, colony aggregation and the inconsistent grazing patterns of amoebae. To overcome this limitation, a suite of plasmid based bioreporters were developed. These plasmids, named pSBR for Surfactant BioReporter, produce a fluorescent signal when the viscosin gene viscA is expressed in P. fluorescens SBW25. Using these tools, the previous observation that surfactant expression increases in response to Acanthamoeba predation was confirmed. However, in this work the response of the ancestral strain matched that of Volcano, a result that was unexpected and may be the result of yet to be explained regulatory features which have diverse effects on the expression measuring techniques. Additionally, an investigation into a P. fluorescens SBW25 luxR homologue (PFLU0925) showed that a mutation in Volcano occurs in a DNA binding helix-turn-helix motif, and is likely to impact the downstream activity of the gene. Based on this, a hypothesised regulatory pathway for viscosin biosynthesis is presented in which the product of PFLU0925 negatively regulates the viscosin operon. Ultimately, the successfully construction and application of the SBR plasmids present an invaluable technique to investigate the intricacies and dynamics of viscosin expression in P. fluorescens SBW25. The observations made here validate the need for single cell methods when investigating complex single celled interactions.
Open Access
Computations with Wang tiles.
(2023) Hogan, Stephanie
In this thesis, we explore the concept of Wang tiles, which are polygons with colours on their edges. A set of such tiles can be used to tile the plane by placing the tiles side by side such that corresponding edges have the same colour. Rotations and reflections are not allowed. We discuss the history of Wang tiles and examine two methods for carrying out computations with them. One method simulates a Turing machine and the other uses ‘signals’. We present multiple new tile sets of square, hexagonal, and octagonal Wang tiles which are used to perform computations. To the best of our knowledge, these are the first examples of octagonal Wang tile sets and dihedral Wang tile sets. Additionally, we present two proofs establishing that our new square tile sets for addition and computing the Fibonacci sequence uniquely tile the plane. Furthermore, we disprove previous claims of unique tilings for three square tile sets used for addition, computing the Fibonacci sequence, and computing the prime numbers.
Open Access
The fruit loop : how multi-nodal interstices of food commons can aid in building community resilience.
(2023) de Almeida e Silva, Claudia
One in five children in Aotearoa New Zealand are living in households with severe to moderate food insecurity. Literature has well established the relationship between food insecurity and people of low-socioeconomic areas. The COVID-19 pandemic and the on-going increase in the price of food has highlighted how fragile the food system is nationally. Alternative food networks, such as community gardens, have taken on much of the burden for aiding local food security, but there is only so much that they can do alone. This study aimed to understand how to move beyond the limitations of community gardens by looking at how multi-nodal food interstices of food commons could aid in building community resilience. The research used a case study of The Fruit Loop, a multi-nodal food interstice project being developed in Ōtautahi-Christchurch. Semi-structured interviews were also undertaken with the residents of Bromley, a low socio-economic neighbourhood in Ōtautahi. The interviews sought to understand the current experiences of food access in the community, what people’s limitations to growing their own food were, and what desires and concerns residents had for the Fruit Loop. The key findings were 1) that the Bromley community has limited food access due to time and transport; 2) growing food was restricted by limited confidence, knowledge, time, and resources; 3) the main concerns for the Fruit Loop were related to people’s lack of trust in the community alongside their perceptions of aesthetics and socially acceptable behaviour; and 4) the Fruit Loop would aid the food resilience in Bromley. Recommendations were made for the Fruit Loop to consider a sub-committee of Bromley residents, an institutional partnership for management of the Loop, and to utilise the Mauri Ora Holistic Wellbeing toolkit. This study adds to the research on socio-spatial relationships with urban food resilience.
Open Access
The growth and reproductive biology of the half crab Petrolisthes elongatus Milne Edwards 1837
(2000) Hannam, Eden
The focus of this thesis is the growth and reproductive strategies of the Half-crab, Petrolisthes elongatus around the Kaikoura Peninsula. Breeding in P. elongatus is seasonal and egg-bearing females are found during summer months, the breeding cycle was studied over the August 1998 until March 1999. The first eggs are deposited in September, and there are no egg bearing females within the population by March. Females are able to produce two broods a year, with their ovaries maturing while they carry their first brood. Moulting does not occur between broods, and egg development appears accelerated in the second brood suggesting some temporal difference. Recordings of the mating behaviour of P. elongatus revealed that interactions prior to mating are brief. There is no moulting prior to mating, no mate guarding behaviour, and mating itself is brief. Eggs are laid immediately after mating. Examination of the reproductive organs show differences in the gonopore aperture. The female opening appears plugged, while the male hinged. Morphological studies reveal the detail of the male pleopods which suggest adaptation for spermatophoric tape transfer. The fifth pereopod was also examined, exposing its complex structure used for grooming and its similarity to the fifth pereopods in other anomurans. Attempts to record the interval and increment of P. elongatus moulting failed due to high mo1iality. Moulting appeared negative at times particularity in colder weather. The need for supplemental feeding was reinforced as P. elongatus was not able to maintain itself in laboratory conditions with filter feeding alone. The few surviving crabs suggest that moult increment is approximately the same across all size ranges, meaning that the percentage moult increase reduced as crabs got bigger. Using the allometic equation on population samples there appeared to be no major phase changes or sexual dimorphism with the exception of female abdomen size, which showed both phase and dimorphism change. In conclusion the mating and growth of Petrolisthes elongatus confirms its placement with the grouping c!nomura. Its similarity in morphology and lack of mating behaviour suggest a relationship to other members of this grouping.
Open Access
The motives behind presenteeism : a study comparing differences self-identified chronic condition status and the motives for presenteeism.
(2023) Campbell, Hannah Rachel
The impact of presenteeism within the workplace has been established. However, the impact of chronic condition status- no, mental, physical or both, is less known. To investigate these differences, 299 participants from across the globe participated in an online multi-item survey that focused on group differences in chronic health status for presenteeism, its associations between approach and avoidance motives, and their associations with social support and psychosocial safety climate. The results found a significant difference between those with both mental and physical conditions level of presenteeism. The results established that having physical or both chronic health conditions raised the likelihood of engagement in avoidance-motivated presenteeism. Social support indicated a significant negative relationship with avoidance motives, and PSC established a significant positive relationship with approach motives. These findings suggest that having both chronic physical and mental health conditions influences the likelihood of engaging in avoidance-motivated presenteeism and could benefit from perceived social support within the workplace.
Open Access
The drivers and composition of microbial communities associated with Pisolithus spp. sporocarps.
(2023) Arkhangelskaya, Antonina
Pisolithus spp. are ectomycorrhizal fungi that can grow in harsh acidic environments such as mines sites, geothermal soils and road verges all over the world. In New Zealand, their distribution is restricted to geothermal areas of Taupō Volcanic Zone of the North Island where they grow in association with Kunzea tenaucaulis and Leptospermum scoparium. Researchers have found diverse microbial communities inhabiting Pisolithus fruit bodies growing in geothermal areas in Yellowstone National Park, although the role these microorganisms play in fungal life cycle is not clear. This research explored the composition, diversity and the ecological drivers that shape the microbial community structure of Pisolithus spp. sporocarps in the Taupō Volcanic Zone (TVZ). Various factors such as soil metal composition, Pisolithus phylogeny and soil microbial community structure were all investigated as possible drivers of the microbial community structure. The microbial communities and chemistry of 29 Pisolithus sporocarps and adjacent soil samples from three sampling locations from the TVZ were analysed. Microbial community composition was determined via Illumina MiSeq next generation sequencing, and metal content of soils and sporocarps was analysed via ICP-MS. Identification of Pisolithus species via Sanger sequencing proved to be challenging and additional RFLP analysis was needed for the majority of Pisolithus samples. Patterns of bacterial distribution within Pisolithus sporocarps resembled patterns of bacterial distribution in adjacent soils but with different relative abundances. Proteobacteria dominated Pisolithus spp. sporocarps accounting for 21 – 85.5 % of bacterial reads, whereas soils were dominated by Actinobacteria (17.4 – 70 %). Chloroflexi were significantly more abundant in soils. Archaea from Thermoplasmatota and Crenarchaeota phyla were detected only in soils, but not in Pisolithus sporocarps. Pisolithus intrasporocarp microbiomes were dominated by bacterial genera Staphylococcus, Thermus in all three sampling locations (Kuirau Park, Craters-of-the-Moon and Rotokawa). Mycobacterium spp. and bacteria from Burkholderia-Paraburkholderia-Caballeronia cluster were abundant in many Pisolithus sporocarps. Thermus spp. were not detected in soils which might suggest they find refuge from acidic environment within Pisolithus spp. sporocarps where they are enriched. Pisolithus spp. sporocarps from Taupō Volcanic Zone of New Zealand were shown to harbor diverse microbial communities. However, a lack of taxonomic diversity of the collected Pisolithus specimens restricted an assessment being made to whether sporocarp phylogeny was a microbial community driver. Of the other factors investigated, sampling location was found to explain more variance in microbial community composition than source (soil or sporocarp), which suggests that physicochemical properties of different sites within Taupō Volcanic Zone play more important role than the source of these communities. This observation may in part be attributed to the metal content of the soil, which explained some of the variance in microbial community dissimilarities in soils.