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Identifying Heterogeneity in SAR Data with New Test Statistics
No full textThis paper presents a statistical approach to identify the underlying roughness characteristics in synthetic aperture radar (SAR) intensity data. The physical modeling of this kind of data allows the use of the Gamma distribution in the presence of fully developed speckle, i.e., when there are infinitely many independent backscatterers per resolution cell, and none dominates the return. Such areas are often called “homogeneous” or “textureless” regions. The GI0 distribution is also a widely accepted law for heterogeneous and extremely heterogeneous regions, i.e., areas where the fully developed speckle hypotheses do not hold. We propose three test statistics to distinguish between homogeneous and inhomogeneous regions, i.e., between gamma and GI0 distributed data, both with a known number of looks. The first test statistic uses a bootstrapped non-parametric estimator of Shannon entropy, providing a robust assessment in uncertain distributional assumptions. The second test uses the classical coefficient of variation (CV). The third test uses an alternative form of estimating the CV based on the ratio of the mean absolute deviation from the median to the median. We apply our test statistic to create maps of p-values for the homogeneity hypothesis. Finally, we show that our proposal, the entropy-based test, outperforms existing methods, such as the classical CV and its alternative variant, in identifying heterogeneity when applied to both simulated and actual data
Fabrication and Characterisation of a Carbon Nanotube Field Effect Transistor Aptasensor Platform
No full textCarbon nanotube field effect transistors (CNT FETs) are known to be viable platforms for aptasensors, a type of biosensor. Little work has been done in determining the relationship between the CNT network and aptasensor sensitivity. This is partly due to the unavailability of fabrication methods to control CNT network semiconducting purity, CNT bundling, and CNT coverage. CNT FETs will have electrical properties which are related to their semiconducting purity and their network morphologies, specifically the amount of CNT bundling and CNT network coverage. It is expected that for unbundled CNT networks that at certain semiconducting purities and network densities that metallic-semiconducting (m-s) junctions will dominate conduction. These m-s junctions are known to be important to aptasensor sensitivity.In this thesis a new automated atomic force microscopy (AFM) analysis method to characterize CNT bundling and network coverage has been developed. The automated AFM analysis method uses a custom written MATLAB program which fits the height histograms of the images to Gaussian peaks. The positions and areas of the Gaussian peaks can be used to calculate average CNT bundle diameter and coverage. The automated AFM analysis method has been demonstrated to be able to the determine average CNT bundle diameters in CNT networks of various morphologies, which can be used to determine the presence of any CNT bundling in the networks. The average bundle diameters characterized by the automated method were found to be lower than the true average bundle diameters determined from manual tracing. Although automated analysis does not determine true average bundle diameter the average bundle diameters determined form automated analysis were found to be related to the true average bundle diameter and therefore can be used to compare across networks. The automated AFM analysis method has also been demonstrated to be able to estimate CNT network coverage. The automated method does not provide the true coverage of the CNTs as it includes broadening of the CNTs due to the AFM tip but does provide a value which will depend on network coverage allowing for comparison between networks of different CNT densities.Various rounds of CNT network deposition have been performed with the intent of depositing unbundled CNT networks of varying CNT coverage and semiconducting purity. The fabrication rounds have been characterized using the new automated AFM analysis method. It has been found that unbundled CNTs can be deposited using aqueous surfactant CNT dispersions purchased from NanoIntegris, IsoNanotubes, deposited onto SiO2 functionalized with poly-L-lysine (PLL) as an adhesive for the CNTs. This method of deposition was found to be unable to deposit CNTs at a uniform and controlled coverage due to the coffee-ring effect, an effect that causes the dispersed CNTs to travel to the edge of a drying drop. It was also found that this deposition method is unable to deposit metallic CNTs from metallic IsoNanotubes solution, possibly due to the different surfactants used to disperse the metallic CNTs. It was found that a variation on the deposition method which involves doing deposition in a humid environment has allowed for better coverage control, and for metallic CNTs to be deposited at greater densities. Deposition of a network of 90% semiconducting CNTs followed by a network of 99% semiconducting CNTs has been demonstrated which may be able to be used to vary semiconducting purity.Raman spectroscopy has been performed on the CNT networks made from various semiconducting purities: 99.9% semiconducting, 90% semiconducting, and 99% semiconducting with 90% metallic CNT spiking. Raman spectroscopy has been able to verify the CNT diameter ranges given by the supplier, 1.2 nm to 1.7 nm. Raman spectroscopy has also been able to verify network uniformity in terms of coverage and amount of bundling that had been characterized by AFM. Peaks associated with metallic CNTs have been identified in the G-bands with two laser energies, 2.41 eV and 1.96 eV, which are resonant with mostly semiconducting and mostly metallic CNTs respectively. These peaks have been able to confirm the addition of metallic CNTs for the 99% semiconducting networks which have been spiked with 90% metallic CNTs but more work is needed to correlate the peaks to actual metallic network purity.Finally, CNT FETs fabricated from the CNT networks have been characterized electrically and used for sensing of adenosine and phenylalanine. It was found that the CNT FET characteristics of the 99.9% and the 90% networks did not vary significantly. Both had low subthreshold swings when gated using an ionic liquid gate, below 100 mV/dec. It was found that in some cases subthreshold swings were higher due to the presence of bundling in the networks. Both 99.9% and 90% semiconducting CNT FETs have been using for the sensing of adenosine, and both showed a maximum response at an adenosine concentration of 100 pM. Current responses at the 100 pM adenosine additions ranged from 1 nA to 30 nA with no differences in current response seen based on the CNT purity. Networks made with 90% semiconducting CNTs have also been demonstrated for the detection of phenylalanine.The maximum response for phenylalanine sensing was at a phenylalanine concentration of 8.5 μM, and in this case current responses at the addition were between 1 nA and 6 nA. The differences in the sensitivity of the adenosine and phenylalanine sensing are likely due to differences in the aptamer structures.</p
Multi-target Genetic Programming for Nutrient Assessment in Fish
No full textThe Cyber-Marine project aims to maximise the utility of commercial fish by using Artificial Intelligence (AI) supported tools and non-invasive chemical methods to assess their nutrient content. Vibrational Spectroscopy has proven to be a reliable method to determine molecular characteristics of a product. Particularly, it has gained prominence in evaluating the nutrient level of produce through statistical modelling techniques, such as Partial Least Squared regression (PLSR). This thesis investigates the use of Machine Learning (ML) to relate spectral data of fish with their nutrient levels. Within ML algorithms, Genetic Programming for symbolic regression (GPSR) emerges as a notable approach, producing models that exhibit generalisability and interpretability. As an extension of GPSR, multi-tree GP (MTGP), provides a platform that can simultaneously train models for several nutrients or bioactive components. In this thesis, significant enhancements and modifications are made to key aspects of MTGP, including its evolutionary process, by the introduction of new genetic operator, and the evaluation function, through the use of a distance metric. These are designed not only to leverage the relationship between the spectral information and bioactive components, but also to optimise the interplay between different target variables thereby maximising the capabilities of the algorithm.</p
Understanding Causes of Water Quality Decline in an Aotearoa New Zealand Ecosanctuary through Paleoenvironmental Analysis
No full textLake eutrophication, specifically as a result of anthropogenic activity and industrial land management, is a significant global and local issue, impacting water quality in lakes worldwide. In Aotearoa New Zealand, eutrophication is widely acknowledged and increasingly being recognised as a critical issue. Short monitoring records, which typically only begin after a lake has started to deteriorate, prevent us from understanding the triggers of eutrophication and therefore requirements for lake restoration. Employing paleolimnological techniques allows for the reconstruction of high-resolution time-series data and is the only approach permitting extensive investigation and analysis of lake and catchment ecosystem change where historical data or oral histories are unavailable. This thesis focuses on Rotokare, a eutrophic lake in Te-Ika-a-Māui/the North Island located within a stable, forested catchment, and uses paleolimnological techniques with particular consideration of how changing landuse has impacted water quality. This thesis aimed to establish if Rotokare has always existed in a highly eutrophic state, or if not, if poor water quality was triggered by changing land management or an alternative catchment disturbance. Reconstruction was achieved via a multi-proxy approach, incorporating hyperspectral imaging, cladocera sampling, micro-XRF scanning, eDNA analysis, geochemistry, palynology, and temperature modelling.Water quality at Rotokare experienced pronounced changes around ~1970 CE, transitioning from a stable lake characterised by low productivity and biomass to a system dominated by cyanobacteria blooms, high productivity and biomass, and changing in-lake communities. The timing of this transition was unusual as it did not correlate well with human activity in the Taranaki region. The pre-human environment was dominated by mature forest, with vegetation communities undergoing slight changes following Māori arrival at ~1400 CE, demonstrating some subsistence horticulture in the catchment. Following European arrival (~1880 CE), vegetation communities underwent further modification, with some reduction in sub-canopy tree populations. Similarly, minimal evidence of intensive farming (post-1950 CE) was found in the lake sediment. This suggests that, unlike many lakes in Aotearoa, the onset of poor water quality at Rotokare was triggered by changes in the catchment unrelated to changes in land management. Both fertiliser (superphosphate) application and sudden sediment influxes (e.g., following storm events) are unlikely triggers for observed poor water quality. The introduction of Eurasian perch in 1900 CE is the probable trigger for poor water quality, with the fish disturbing in-lake communities and increasing turbidity. However, an observed rise in temperature from ~1950 CE onwards is likely entrenching poor water quality and contributes to the severity of algal blooms. This research demonstrates that water quality degradation can occur even in lakes with relatively pristine catchments, demonstrating the impact of the introduction of new species to ecosystems.</p
Coupled atmosphere-ocean response of the southwest Pacific to deglacial changes in Atlantic meridional overturning circulation
No full textThe last glacial termination was characterised by millennial-scale episodes of warming and cooling that appear offset between the hemispheres. It has been proposed that this bi-polar seesaw is the result of climate system feedbacks. A key debate, which remains unresolved, concerns the relative roles of the atmosphere and oceans in transmitting these climate responses between the hemispheres. In this study we present quantitative climate proxy data to show that air temperatures in New Zealand, as recorded by mountain glaciers, tracked millennial-scale warming and cooling of local surface temperatures of the adjacent Tasman Sea throughout the last glacial termination. Both realms were dominated by warming between 18 ka and 12 ka, interrupted by a multi-centennial to millennial-scale cooling event centred on 14 ka, coincident with the Antarctic Cold Reversal. Reconciling our climate proxy evidence with a transient climate model simulation of the glacial termination, we find that the timing and amplitude of temperature changes are consistent with changing Atlantic meridional overturning circulation (AMOC). The southwest Pacific region displays a particularly sensitive response to AMOC intensity changes, despite its far-field situation from the North Atlantic. This sensitivity represents the combined impact of fast-acting oceanic teleconnections and regional atmosphere-ocean response associated with changes to the southern westerly winds. Our findings highlight that recent hypotheses promoting the role of southern westerlies as a critical component of deglaciation may be complementary to, rather than competitive with, the bipolar seesaw paradigm
Ko Wai Mātou
No full textLandscapes are an integral component for the identity of people. The Māori people express an interconnectedness between land and people that form one's identity. Mātauranga Māori; the traditional indigenous knowledge of the Maori people originates from the natural world (Te Taiao), where mountains, rivers, lakes, forests and place are essential within Māori identity (Turangawaewae).Since the first British ships arrived at Aotearoa/New Zealand, traditional Māori knowledge has degraded in both theory and practice due to the ongoing dominance of western society. Western development continuously degrades the health of the natural environment. Forests and waterways to this day are cleared and buried for the urban expansion of modern cities. This constant alteration of the natural landscape diminishes the cultural connection Māori once had with the natural landscape and is only becoming scarcer with time.Mātauranga Māori is slowly growing within the landscape architecture field as a progressive way forward to honour Te Tiriti o Waitangi. Throughout this research Māori knowledge is used to facilitate an innovative approach in representing Māori values within landscape architecture design. Māori focused frameworks and methods are investigated to provide a strong connection between Māori principles and the natural landscape. It is with intention that the design framework within this study can be replicated and aid designers with clarity regarding Māori representation.Running its course below the urban infrastructure of Wellington City, Waimapihi Stream was once rich in resources for the local lwi (Tribe) of Te Whanganui a Tara (Wellington) before being buried over a century ago due to the demand of settler development. The Waimapihi stream still holds a significant amount of cultural value to the local lwi of Te Whanganui a Tara and this research will look at opportunities to represent this cultural significance through landscape design and Mātauranga Māori led frameworks to increase the awareness and importance of this buried waterway.This design-led research investigates Mātauranga Māori design principles and multifunctional green and blue spaces to reclaim Waimapihi as an important part of Wellington's dense urban landscape. It does that by approaching the waterway with a case study research and investigation of the pre-colonial past and bi-cultural relationship of Aotearoa {New Zealand). It finds that by reinstating Wellington's pre-colonial past within a colonial urban environment will provide cultural connection to the natural landscape within an otherwise unrepresented urban sprawl while providing the wider Wellington communities with the health and well-being benefits derived from green and blue infrastructure.</p
Me pēhea te hāpai i te hauora o ngā taiohi o Taranaki mā te mātauranga Māori? How do effective mātauranga Māori initiatives for taiohi in Taranaki contribute to their well-being?
No full textThis research proposal aims to investigate the influence of effective mātauranga Māori initiatives on the well-being of taiohi (youth aged 16-24) in the region of Taranaki. Recognising the significance of Indigenous knowledge systems and cultural practices in nurturing the next generation, this study seeks to understand how these initiatives contribute to the overall wellbeing of taiohi. By exploring the specific components and approaches of mātauranga Māori initiatives, this research aims to shed light on their potential to empower taiohi, strengthen their cultural identity, and enhance their overall holistic development. The findings of this study will not only contribute to the existing body of knowledge on Indigenous education and well-being but also provide insights for educators, and community leaders in designing and implementing effective initiatives for taiohi in Taranaki.</p
The Politics of Presence in the 2023 Election: Descriptive, Symbolic and Substantive Respresentation
No full textNo description supplie
The Socio-Legal History of The Rotorua Township Agreement - Trick or Treaty?
No full textThis thesis aimed to analyse and discuss the socio-legal history of an agreement made between Ngāti Whakaue and the Crown known as the Rotorua Township Agreement, which is one of several regional agreements or treaties that the colonial (Government) and iwi Māori negotiated after the Treaty of Waitangi in the later nineteenth century. After the signing of the Treaty of Waitangi in 1840, there were three iwi in Aotearoa who entered into distinct treaties with the Crown: Ngāti Whakaue of Rotorua, Tūhoe of Te Urewera and Ngāti Maniapoto of the King Country. Though the focus of this thesis is Ngāti Whakaue and the Rotorua Township Agreement (1880), it will be revealed that the Crown used these regional agreements to deceive Māori located in the Central North Island into believing they possessed sovereignty over their lands when, in hindsight, they did not. Do these regional treaties count under New Zealand or international law? This critical question was thoroughly examined in this thesis. The central focus of this thesis is the Rotorua Township Agreement. In the late 1870s, the Government wanted to create a township that would become a geothermal and cultural attraction for international tourism. In 1880, the local chiefs of Ngāti Whakaue and Te Arawa signed an agreement with Judge Francis Dart Fenton to set up the township of Rotorua. Was this agreement a trick or a treaty? The Rotorua Township Agreement will be compared to similar agreements or treaties made with Tūhoe (Urewera District Native Reserve Act 1896) and Ngāti Maniapoto (Te Ōhākī Tapu 1882-1885). The final analysis of this research compared these three agreements or treaties and the socio-legal histories of these three iwi. This comparative analysis aims to assist Ngāti Whakaue, whose Treaty claim remains unsettled, to reach a similar deal as Tūhoe and Ngāti Maniapoto, who have successfully settled their Treaty claims in recent years. With the recent change in New Zealand Government, the Treaty of Waitangi is now more under threat than ever. Therefore, all New Zealanders, Māori and non-Māori, need to unite and support iwi such as Ngāti Whakaue in their efforts to settle their claims and regain their ‘tino rangatiratanga’ promised them under Te Tiriti o Waitangi. A Māori proverb, or ‘whakataukī’ states: ‘Ahakoa ngā uaua, kia manawanui!’ – ‘Despite the hardships, be strong-hearted’.</p
Improving current wasp management towards eradication
No full textSocial insects are successful and globally significant invaders. Compared to ongoing suppression, eradication is seen as an ideal solution and cost-effective in the long term. Wasp eradication is a worthy target but with current technologies and approaches it may be a difficult one to achieve. In this thesis, I analysed both past and present approaches to invasive species management to identify ways to improve our current wasp management toward the goal of nationwide eradication of invasive social wasps in Aotearoa New Zealand.The success of eradication attempts is not guaranteed and identifying key factors that could influence the success of such management programs would be beneficial. In Chapter 2, I analysed 239 historical and recent insect eradication attempts to identify predictors of eradication failure. I found that sociality is a significant predictor of eradication failure. The data suggested that more recent eradication attempts experience higher rates of success but that the increasing duration of a program is associated with reduced odds of success. The target species' host range and the geographic setting of the invasion were also found to be significant. Cited reasons for eradication failure highlighted the importance of effective control methods, management, and monitoring systems, as well as garnering adequate social and political support. Social acceptance and support for pest management programs are essential to success. In Chapter 3, I spoke to local stakeholders to explore their perceptions of current wasp management and what attempting eradication means for them. I interviewed 13 local stakeholders involved in 7 pest management projects across Aotearoa New Zealand. Q-method analysis identified two major perspectives across the participants. An ambitious perspective emerged where eradication of wasps was the target, and any control method deemed effective could be used to achieve that goal. The second perspective identified agreed that wasps must be managed but were characterised as more holistically minded and less accepting of control methods perceived to have negative impacts or side effects. Education and engagement were highlighted as essential to increase local support for future wasp management. Emphasis not just on technical but social and cultural aspects of wasp eradication is key to management success.Effective control methods are paramount to successful pest management of invasive pests. Understanding why some treatments fail is important to improve management practices. In Chapter 4, I investigated how a common wasp control method could be improved to maximise wasp control. The toxic bait Vespex® was used to control invasive wasps across 64ha of forest near Hanmer Springs, Aotearoa New Zealand. The median reduction in nest traffic at treatment nests was 96.5%. Logistic regression analysis suggests that larger wasp nests, nests further from bait stations, and more isolated nests exhibited lower rates of mortality after baiting. At surviving nests, beta regression analysis suggested that declines in nest traffic were less severe with increasing distance to the nearest bait, but more severe with increasing nest size. Bait uptake varied considerably across bait stations and wasp nests were spatially aggregated, both likely due to aspects of environmental conditions.Understanding and considering potential unintended negative consequences of pest management is critical when attempting eradication. In Chapter 5, I investigated the potential negative impacts of toxic baits used widely in current invasive wasp management on a non-target species the Wellington tree wētā (Hemideina crassidens). In laboratory settings, wētā exposed to bait containing the active ingredient fipronil at all concentrations (0.1%, 0.01%, and 0.001% by mass respectively) experienced significantly higher rates of mortality (70%-90%) compared to control baits (10%) after 2 weeks. A follow-up field study looked to investigate how bait presence may impact wētā survival in a more realistic baiting scenario. Wētā box occupancy was monitored over the course of a simulated wasp baiting program at two forest sites, with bait stations placed within 30cm of half of the boxes. Analysis showed that wētā box occupancy was not significantly affected by bait presence. Additional research will be needed to truly estimate the impact of current wasp management on wētā populations though simple steps may be taken to reduce nontarget effect. In this thesis, I show that social insects are particularly challenging to eradicate. Before undertaking any eradication attempt it is important to consider both logistical and biological aspects of managing a species incursion. Ensuring pest management actions are supported by local stakeholders is critical to project success. Engagement and collaboration are needed to develop effective pest management programs. Research conducted here identifies avenues to improve current management techniques to increase efficiency and efficacy while reducing non-target impacts. These improvements would serve to increase the chance of eradication success by more effectively reducing pest populations but also increasing the social acceptance of the program.</p
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