UC Research Repository

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The UC Research Repository collects, stores and makes available original research from postgraduate students, researchers and academics based at the University of Canterbury.

 

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ItemOpen Access
Navigating politics and trade : how New Zealand's Free Trade Agreements with the United Kingdom and European Union impact Māori economic agents.
(2024) Russell, Cassidy
The nature of the relationship between trade and politics is an area of extensive discussion within academic literature. Trade is often seen as a beneficial agreement between parties; however, what impact, if any, does the political climate impose on trading partnerships? With this in mind, it is essential to understand how this relationship may impact smaller economies, such as Indigenous economic agents, who are subjected to the changes made in the international trade landscape by more significant political and economic powers. Māori, the focus group of this research, are the Indigenous peoples of New Zealand. To date, limited scholarly research has been conducted on political decisions affecting Māori economic agents, presenting a relatively unexplored area of literature. This thesis aims to help fill this void and establish to what extent political or politicised trade decisions shape Māori economic agents’ ability to trade. Two independent approaches are used: a critical discourse analysis employing Fairclough’s framework and an analysis of interviews conducted with the political and academic elite in this field. Qualitative and quantitative research techniques are used within these frameworks to answer the research objective. Interestingly, the impact of politicised trade on Māori economic agents differed depending on the context in which it was examined. At a domestic level, politicised trade is found to positively impact Māori trade outcomes, while from an international perspective, there are concerns their trading opportunities will be harmed. However, this research highlights that greater inclusion of Māori voices in trade decisions will limit these negative impacts and create further opportunities for beneficial growth in trade. This thesis aims to bring the Māori economy into the spotlight, showcasing the attention this area of exploration deserves and to provide discourse that may positively affect Māori economic agents and their wider community.
ItemOpen Access
Investigation of the Lactococcus cremoris (SK11) PIII-type PrtP cell-envelope proteinase as a template for substrate tailored CEP-based construct design.
(2024) Walker, Matt
Cell-envelope proteinases of lactic acid bacteria catalyse the first step in the proteolytic system. They break down proteins from the surrounding media into polypeptides, which are transported via the cells peptide transport system into the cell for further processing. To date, research suggests that changes in the physicochemical properties of residues within the active site region of cell-envelope proteinases are responsible for differences in experimentally determined proteolytic profiles. PrtP’s are a type of cell-envelope proteinase and are ideal templates for engineering tailored substrate specificity. I have focused on the PIII-type PrtP from Lactococcus cremoris, which has multiple domains, including an enzymatically active protease domain (PR domain). This research investigates whether there are non-conserved residues, particularly within the PR domain, that can be targeted to modify substrate specificity or catalytic activity. This is desirable because it will identify residues that can be targeted in protein engineering tailored to specific substrates. For example, to hydrolyse proteins that comprise plant-based milks. Using multiple sequence alignments and visualization of AlphaFold models, four residues within the PR domain that may be important for substrate specificity or catalytic activity are identified. Surprisingly, during this analysis an extended duplicate region within the PIII-type enzymes cell wall spanning domain was identified that may be a defining characteristic of PIII-type PrtPs. Given that the PIII-type PrtP from Lactococcus cremoris has recently been suggested as a promising template for site directed engineering of bespoke CEP-based constructs this work undertook bioinformatic analysis of this protein and attempted to express and purify constructs of this protein. Limitations including fragmentation of the construct and aggregation prior to size exclusion chromatography resulted in being unable to purify useful amounts of the constructs for use in characterization. In conclusion, potentially promising residues of PIII-type PrtP from Lactococcus cremoris that could be used for substrate tailored protein engineering were identified, as well as confirming the catalytic site residues. This information can be used by others to engineer PIII-type PrtP enzymes by substituting these residues to alter the catalytic activity and/or substrate specificity of the protein. This could have commercial utility by developing active constructs with specific substrate specificity that can be used, for example, in manufacturing of dairy alternatives, which had a market value of over US$2.4 Billion in 2023. Other important applications are as diverse as enrichment of foods via the generation of bioactive compounds and the development of enzymes that can break down waste for use in bioremediation efforts.
ItemOpen Access
Connecting Canterbury : the role of economic networks linking pastoral Canterbury and the colonial world.
(2024) Pattie, Jock
Colonial Canterbury is characterised by its association with New Zealand’s wool industry in its earliest days, and the wealth that grew from this industry is the foundation upon which modern Canterbury has built its sense of identity. Sheep farms in Canterbury predate even the arrival of the Canterbury Association in the region, as in the 1840s a few dozen Europeans leasing land directly from Ngai Tahu established farms and sheep runs on Banks Peninsula and around what would become Christchurch. After organised settlement began following the establishment of Christchurch in 1850, European settlers established hundreds of farms across the region, kickstarting an agricultural and pastoral industry that has persisted to this day. The economic networks that facilitated the establishment of this industry had many levels, encompassing everything from the roads and railways that linked the interior of the region to the ports, to the agents who organised the shipping, insurance and sale of wool in London. By supplementing the array of scholarship in existence with a selection of primary material, this thesis will seek to show how the varied facets of colonial Canterbury’s economy were connected to the demands and influences of the wider Imperial economy within which it was set. This thesis does not attempt to explain specific methods by which Cantabrian colonial industries were organised and run, nor does it try to determine how successful these industries were in creating wealth for individuals. Rather, this paper seeks to link together many disparate aspects of the economy that acted to facilitate the continued expansion of the colony, the steady flow of produce out of it into the imperial market, and the supply of necessary supplies from the Imperial centre to the colonial periphery. Particular attention will be given to the impact various parts of the network had on influencing each other, Detailing how the demand for raw materials to fuel the Industrial Revolution kickstarted the expansion of sheep farming to Australasia, which in turn demanded infrastructure to move wool out of the colony, and finally how stock agents and finance supplied the necessary capital to have made the development of Canterbury possible.
ItemOpen Access
Feeling safe to speak up : the role of leader behaviours and psychological safety in the formal hierarchical context of New Zealand legal practice.
(2024) Clarke, Emma Jane
This PhD research investigates the role of psychological safety in the relationship between leadership and employee wellbeing, and aims to advance our understanding of how leaders can foster a psychologically safe climate and enhance wellbeing in formal hierarchical work contexts. This research explores how psychological safety improves employees’ desire to continue working in high-demand, high-stress workplaces and to provide deeper insight into employee turnover and retention in the context of New Zealand legal practice. Psychological safety is defined as a belief among team members who respect and trust each other that they are safe to take interpersonal risks, make mistakes, and address issues without fear of being rejected by their leader and fellow team members. Law firms often have a formal hierarchical structure, which is characterised by significant power differences and control mechanisms that can prevent employees from raising concerns with their leaders about issues in the workplace. The present research contributes to legal practice by highlighting the important role that leaders play in hierarchical workplaces where turnover is high, particularly among early career women, and where many lawyers suffer from poor wellbeing. Three empirical studies were conducted with two data collections. A quantitative survey approach was used for data collection in the first study and interviews were conducted for the second and third studies. Survey results show that psychological safety is a mechanism through which leadership influences employee wellbeing (Study 1). Leaders who develop high-quality relationships with employees by displaying vulnerability and through role modelling capabilities and emotional regulation skills; who address wellbeing issues fairly and promptly; and who provide regular and timely feedback, help to improve perceptions of psychological safety and employee wellbeing (Study 2). When leaders provide employees with access to resilience-enabling resources, while fostering a climate of psychological safety, this contributes to a greater desire to continue working in high-demand roles, particularly for women (Study 3). This study uncovered gendered differences connected to strategies for coping with high workload and stress, as well as differing views on the factors that influence lawyers to leave legal practice. The research presented in this thesis has multidisciplinary applications and demonstrates that when leaders behave in a way that counteracts the barriers brought on by formal hierarchical structures, perceptions of psychological safety will improve and positively influence employee wellbeing and retention. To reduce dysfunctional turnover, leaders should focus on supporting employee resilience, while developing a learning culture where employees feel comfortable voicing their concerns and ideas without the fear of retribution.
ItemOpen Access
Modelling and adaptive control of quadrotor unmanned aerial vehicles
(2023) Morris, Daniel
Unmanned aerial vehicles (UAVs) have the potential for use in a number of high-precision applications, including industrial inspection and precision agriculture. Quadrotor UAVs are one of the most commonly used UAV platforms, as they are agile, lightweight and relatively inexpensive. A significant limitation of current quadrotor UAV flight control systems is their inability to adapt to changing flight conditions, as well as their inflexibility to changing airframe properties. Conventional methods utilise linearised or simplified models of flight dynamics which have limited capacity to respond to changing system parameters, and use control methods that are limited to low accuracy applications or to specific flight conditions. The development of a generalised, flexible flight control system for quadrotor UAVs would allow for a greater range of applications across a wide range of airframes, from specialist to civilian UAVs. This work investigates the development of such a flight control system. Firstly, a nonlinear dynamics model of a quadrotor UAV was developed. This dynamics model used a quaternion orientation representation; the majority of existing models use an Euler angle representation, which have known singularities, whereas using a quaternion representation allows for singularity-free orientation representation as well as more efficient computation. The dynamics model was developed in a minimal sense, with the core dynamics effects derived from first principles. The model was then parametrised into 13 parameters, using a lumped parameter approach as the initial model was structurally non-identifiable. Unmodelled non-ideal dynamics effects were included by augmenting each dynamic axis with a parameter representing the total dynamic impact of unmodelled effects on that axis. The dynamics model developed includes aerodynamic drag effects modelled using the Rayleigh drag equation. There is little consensus in the literature on how best to model aerodynamic drag for a multirotor UAV, so an experimental study of the drag behaviour of a quadrotor airframe was conducted. A quadrotor airframe was mounted at a range of pitch and yaw angles in a wind tunnel, and the drag forces on the airframe were measured across a range of wind speeds. The results of this study showed that a Rayleigh drag model accurately models the UAV’s aerodynamic drag behaviour. An experimental flight platform was then developed to allow for physical data collection. This platform consisted of a standard cross configuration quadrotor airfarme, with Hall effect sensors added to measure the angular velocities of the propellers. The Hall effect sensors and inertial measurement unit used were calibrated against known reference values, using test fixtures designed for each sensor, and their signal-to-noise ratios (SNRs) were derived, with all sensors having SNRs greater than 25 dB. Ground truth flight data was obtained using a motion capture system, and required the implementation of synchronisation between the onboard sensor clock and the external motion capture clock. A modified form of the IEEE 802.11 clock synchronisation protocol was implemented, with an infrared LED used to obtain a 20 Hz synchronisation pulse with the motion capture system. Next, identification of the model’s parameters was investigated. Parameter identification methods for UAV systems in the literature are typically applied prior to flight operations, whereas this thesis considers the use of such methods during flight operations to allow for online tuning and adaptation to changing flight conditions. Four common white-box parameter identification methods were implemented and were applied to both synthetic data and experimental flight data in an open-loop control configuration. Error metrics for the performance of each method were defined, including a definition of pose error that captured both the overall desired behaviour of the airframe, as well as including the quaternion orientation representation. Application of the parameter identification methods to the synthetic data showed that Levenberg-Marquardt gradient descent had the best performance, including when synthetic noise was added to the simulated data, with this method yielding pose errors 75% smaller than the other methods at SNRs down to 20 dB. Levenberg-Marquardt gradient descent was also the most performant method on the experimental flight data, with median quaternion distance errors below 0.3 rad, but maximum distance errors comparable to the experimental flight envelope. Finally, a nonlinear model predictive control system that incorporated both the nonlinear dynamics model and online parameter identification was developed. A novel cost function based upon the pose error metric was used to prioritise trajectory tracking, with comparison with a standard quadratic cost function showing that the pose error cost function gave better tracking performance and was better able to track target quaternion orientations. The controller was tested on synthetic flight trajectories, including airframe parameter changes and external wind disturbances, and was shown to maintain accurate trajectory tracking when subjected to these conditions, although the controller’s high computation cost prevented its use in an experimental setting.