2,896 results for ResearchSpace@Auckland, 2016

  • Tsunami Inland Structures Interaction and Impact of Floating Debris

    Shafiei Amraei, Seyedreza (2016)

    Doctoral thesis
    The University of Auckland Library

    Civil engineers have long known that large forces from tsunamis can be imposed on coastal structures. This was made obvious by the recent 2011 Japan tsunami, which also emphasised that the risk of tsunami damage is no less significant than the risk of earthquake damage. New Zealand, due to its exposed location, is also at high risk of tsunami impact by local-, regional-, and distant-source tsunamis. Although some efforts have been made to determine tsunami loads on structures, there are still discrepancies among the limited number of published design guidelines. Data on actual tsunami loads on structures are rare, hence physical modelling of the interaction between a tsunami and a structure is vital to explore the problems associated with tsunami impact, and thereby to improve the existing knowledge of tsunami engineering. This study comprises an experimental investigation of tsunami bore interaction with structures located near coastlines. Specific aims of the study were accomplished by investigation of: (1) the impact of a tsunami bore on a square prism structure having different orientations to the flow direction; (2) the impact of a tsunami bore on a cylindrical structure; (3) the effect of structure stiffness on tsunami bore impact; (4) the impact of a tsunami bore on an elevated structure, in which a square prism structure base was raised at different elevations above the ground (???base elevation???); (5) the tsunami-borne debris impact on structures through development of a new technique, utilising a smart debris device; (6) factors affecting debris impact forces. The experiments were conducted in a 14m long, 1.2m wide and 0.8m deep wave flume, separated from a reservoir using an automatic gate. The gate was designed to rapidly release water into the flume to simulate a tsunami bore. Measurements were made of the bore heights and velocities, based on which an empirical equation, with the basic form of the gravity wave velocity equation, is proposed for calculating the bore propagation velocity. For all structures, forces and moments were measured at the base of the structure, using a multi-axis load cell. For forces and pressures exerted on a square structure, a square prism with 300mm??300mm cross-section and 600mm height was made from acrylic sheets. The vertical distribution of bore induced pressure was measured on the front face of the square prism. The effect of structure orientation on the forces and pressures was investigated, with the structure???s front wall oriented at 30??, 45??, 60??, 90?? and 135?? to the flow direction. The bore induced forces were theoretically computed assuming that the total stream-wise force is due to the hydrostatic force plus the hydrodynamic force, and the upward force is due to the buoyancy only; the results were validated using the experimental data. Drag coefficients for the square prism at different orientations ranged from 1.15 to 1.65. For forces and pressures exerted on a cylindrical structure, a cylinder with 300mm outer diameter and 600mm height was made from acrylic. The vertical and angular distributions of bore induced pressure were measured on the front face of the cylindrical structure perpendicular to the flow direction, and at 30??, 45??, 60??, 90?? and 135?? to its original alignment. Similarly to the square prism, the bore induced forces were computed and validated using the experimental data, giving a drag coefficient of 0.65. For forces and pressures exerted on different structure stiffnesses, four different square prism structures, each with 300mm??300mm cross-section and 600mm height, were made from various thicknesses of acrylic sheets. Deflection of the top of the square prism structures was measured, with the deflection angles ranging from 0.01?? to 6?? with respect to the flume vertical axis. The structure deflection increased with decreasing stiffness of the structure. The vertical distribution of the pressure was not affected by varying the structure stiffness. Also, the bore induced forces measured at the structures??? bases had similar magnitudes for different stiffnesses. The results demonstrated that the bore induced pressure and forces are independent of the structure stiffness. However, this conclusion is valid only when the effect of P-delta is not significant (i.e. for small P value), and should be validated for more significant effect of P-delta (i.e. for large P value) by adding gravity load on the structure. For forces and pressures on elevated structures, the square prism structure was raised above the flume floor at base elevations of 50mm, 70mm and 90mm. Pressure exerted on the underside of the structure base was also measured and the horizontal pressure distribution was investigated. The magnitudes of the bore induced pressures on the underside of the structure base decreased with increasing base elevation. The stream-wise and upward forces due to the bore both decreased with increasing base elevation. Elevating the structure reduced the stream-wise force by up to 50% of that for a non-elevated structure. Also, the upward force for an elevated structure was significantly smaller than that for a non-elevated structure. Empirical equations are presented, to give guidance for the preliminary design of elevated structures under tsunami bore impact. For impact forces of tsunami-borne debris, an accelerometer-equipped disc-shaped smart debris device was used for direct measurement of the acceleration of the debris collision with the structure. An image processing technique was used to detect the angle of the debris at the instant of impact, and subsequently to resolve the acceleration data to horizontal and vertical directions. The measured acceleration data were converted to force using the impulse-momentum formula. The debris impact experiments were conducted for various bore velocities and various debris masses (550, 800 and 1000 g). The debris impact force was found to be a function of the debris mass, velocity, contact duration, and additional mass of entrained water. Additionally, the debris impact force was measured at the structure base, validating the results from the smart debris device. An equation was developed for the debris impact velocity, for a known distance between the location of debris pick-up by a tsunami and the structure. The debris velocity equation was validated using the experimental debris velocities obtained from integration of the measured acceleration data. For factors affecting the debris impact forces, evaluative experiments were carried out by varying debris shape (disc- and box-shaped debris), debris rigidity (rigid and deformable box-shaped debris), and structure stiffness. The results were used to modify the basic impulse-momentum formula by the addition of coefficients that take into account the added mass, the debris impact velocity, the debris shape, deformability of the debris, and stiffness of the structure. The results of this study give practitioners the ability to better analyse the tsunami bore impact on coastal structures. Most importantly, this study provides guidance for the preliminary design of structures that may be impacted by a tsunami bore, including estimation of the total stream-wise force, upward force, and floating debris impact force. Also, this study addresses a major knowledge gap in the design for tsunami impact on structures with different stiffnesses, and structures elevated above the ground.

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  • Automated Residential Demand-Side Management Strategies

    Croft, Aaron (2016)

    Doctoral thesis
    The University of Auckland Library

    There is growing evidence that climate change is becoming one of the major issues facing mankind within the next century. In this context, the electricity sector has been receiving increasing attention over the past decade due to the large amount of carbon it emits. Demand-side management - controlling overall power demand - has been heralded as a potential solution to this problem and while it is common in industry today, residential demand response remains elusively untapped. This is because residential electricity consumers are generally unwilling to sacrfice comfort for often meagre incentives, and the difficulty of controlling such a complex system increases its cost. This work specifically targets these barriers to adoption, proposing an entire demand- side management topology, control algorithm, and novel way of viewing controllable loads. To start, a uni ed load model is introduced which sees all controllable loads represented as batteries with time-varying power and energy values bounded by consumer comfort limits. Then, an algorithm called NES (Net Energy Stored) control is introduced that controls loads modelled in this fashion using a simple, scalable control system. The algorithm operates without making any predictions, greatly enhancing its ability to respond to unexpected events such as reserve provision, real-time pricing, unpredictable local generation, and the load profiles of diverse, human consumers. A practical system was built on low-cost microcontrollers and the algorithm was implemented thereon. A method of validating demand response algorithms is also proposed in this thesis, employing a Monte-Carlo simulation of 100 statistically representative 7-house New Zealand communities using a bottom-up load modelling tool based on large behavioural studies. Several scenarios were explored, covering electric vehicle adoption, varying allowable temperature deviation in hot water cylinders and different wind generation profiles. Then an optimal scenario operating with perfect foresight was implemented as a Mixed Integer Program and used as a benchmark. Both the optimal savings and performance of NES control varied significantly across the 100 communities and across the scenarios, notably performing very well in the most volatile scenarios. On average, NES control obtained 57.4% of the theoretical optimal savings assuming the use of existing residential loads. Increasing the allowable temperature range of hot water cylinders using a mixing valve on the output allowed NES control to extract significantly more savings relative to the uncontrolled case, extracting 68.2% of the optimal benefits if the water temperature is allowed to fluctuate between 55-85 C. At 30% electric vehicle adoption Net Energy Stored (NES) extracts 66.4% of the optimal value. Under different wind profiles NES extracts between 38.8% and 66.0%, showing its sensitivity to the timing and magnitude of wind power. Combining the extremes of all of these scenarios, NES control achieves 63.6% of the optimal results. NES performs marginally worse under a real-time pricing scheme, with 48.2% of the optimal savings extracted in the status quo situation and 56.3% with all technologies combined. Overall these results are promising because NES control does not make any predictions of load, price or wind while its benchmark is afforded `perfect foresight'. Furthermore NES control has been successfully implemented on an ultra-low-cost, ultra-low-bandwidth embedded communications system which performed almost identically over a networked control system as it did in simulation. NES control is therefore a low-cost, readily implementable solution that is well suited to the complex problem of residential demand-side management.

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  • Approaches to Describe and Quantify Uncertainty in Bio-physical Agricultural Computer Simulation Models

    Meenken, Esther (2016)

    Doctoral thesis
    The University of Auckland Library

    The objective was to explore the definition, sources, quantification, and management of uncertainty in bio-physical agricultural deterministic computer simulation models (crop models). One aim was to provide recommendations from a formalised statistical viewpoint on management of uncertainty for a small pool of crop model researchers in New Zealand. These researchers face unique issues with models that describe temperate, island-based conditions. An equally important goal was to identify ways to provide predictions complete with uncertainty bounds beyond those offered by sensitivity analysis. Given these objectives, my focus was on a single model. Section I proposes an uncertainty evaluation (UE) framework to explore how the combined components of a crop model contribute to the overall output uncertainty. Tools to curate information, diagnose the most important sources of uncertainty, and identify UE objectives have been developed. The framework links qualitative and quantitative analysis through a review of techniques for generating and analysing data from such models. Although many elements considered appear in the literature, amalgamation into a united framework is an original contribution. In Section II a detailed description of a case-study model that simulates wheat development is provided. This model provides a concrete foundation by which to demonstrate the UE framework, and illustrates the nature of crop models as constructs upon which mechanistic understanding of real-world systems continues to develop. A theoretical addition to a recent model that combines physiological and genetic characteristics of wheat is proposed based on laboratory based experimental work, reducing structural uncertainty. Finally, Section III is centred on the analysis of simulated data. In particular, it addressed the desire to provide credible intervals for state-space model estimates. This was achieved through fitting a probabilistic Bayesian hierarchical model with MCMC, a general form of data assimilation that recursively updates state predictions based on available data. Credible bounds of both an observed and a latent state variable were estimated for the case-study model. Finally, I summarise how these three sections tie together to resolve research objectives. I discuss the benefits of this research, recommendations and limitations, and propose directions for future work.

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  • Alternate motor pathways for upper limb control: Implications for noninvasive brain stimulation after stroke

    McCambridge, Alana (2016)

    Doctoral thesis
    The University of Auckland Library

    Descending pathways other than the lateral corticospinal tract may play a role in the recovery of upper limb function after stroke. Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that has shown the potential to improve motor function of the upper limb. This thesis investigated the neurophysiological and behavioural effects of motor cortex (M1) tDCS on control of the upper limb in healthy adults and chronic stroke patients. The effects of various tDCS electrode montages on corticomotor excitability were examined, with an emphasis on the proximal upper limb. Transcranial magnetic stimulation (TMS) was used to infer corticomotor excitability of crossed, uncrossed, and transcallosal motor pathways, cervical propriospinal neurons, and intracortical inhibition in M1. The first three experiments examined the effects of dual-hemisphere tDCS on the excitability of propriospinal neurons, separate motor pathways, and upper limb coordination. Dual-hemisphere tDCS modulated subcortical excitability to cervical propriospinal neurons, and transcallosal inhibition. The electrode montage anodal tDCS (a-tDCS) was examined in two experiments with healthy adults and in the final thesis experiment with chronic stroke patients. The effects of a-tDCS varied in healthy adults. The variability of tDCS after-effects on motor evoked potentials were correlated with an individual???s preferential recruitment of early vs late indirect (I)-waves. In another experiment, it was revealed that short-interval paired-pulse TMS can be used to examine intracortical inhibition on uncrossed motor projections to the proximal upper limb. This novel TMS paradigm provides new opportunities to investigate the role of the ipsilateral M1 during movement. In the final experiment, the interhemispheric imbalance model for chronic stroke was challenged. Anodal tDCS of the contralesional M1 was hypothesised to improve motor function of chronic stroke patients that may rely on alternate motor pathways for upper limb control. Motor function of the paretic arm was positively affected by contralesional a-tDCS for patients who had greater spasticity. By identifying novel biomarkers this may help individualise tDCS protocols for future clinical trials.

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  • He Ana, He Whakairo: Examining M??ori Belief of Place Through the Archaeological Context of Rock Art

    O'Regan, Gerard (2016)

    Doctoral thesis
    The University of Auckland Library

    There is a historical tension between archaeologically and traditionally informed M??ori perspectives in the management of M??ori archaeological heritage. A central concern is the extent to which past beliefs that M??ori held about particular places can be examined by archaeological methods and therefore factored into archaeological assessments of sites. This research investigated the extent to which such beliefs can be archaeologically recognised in two of New Zealand???s most notable rock art localities. It proposed that the way M??ori conceived of places may be archaeologically visible in the positioning of the marks they made. A multi-scalar examination of the archaeological context of the rock art localities involved re-evaluation of imagery and test excavations at rock shelters, and reviews of the surrounding archaeological, historical and land use histories. These provided an understanding of the formational processes that have resulted in the surviving archaeological record. This in turn provided the basis to assess the contexts of rock art and the extent to which spatial patterns of association indicative of past belief can be demonstrated as contributing to that formation. In a few cases where the spatial arrangements of rock art figures and other features did allow ancestral associations to be suggested and a ritual deposit to be recognised, these were considered in relation to insights of a traditional M??ori view informed by ethnographic and ethnohistorical accounts. More generally, however, preservation issues at one or more of the different spatial scales confounded the demonstration of such patterns. Comparison between the Taup?? and South Canterbury study areas demonstrate how those issues impact on the record, and how the application of current archaeological assessment practices are unlikely to provide the scope to scientifically demonstrate the role of belief in shaping that record. The tension arising from how archaeological method can factor belief into assessments of such M??ori heritage places is likely, then, to remain unresolved. Key words: M??ori, Rock art, Archaeological context, Heritage assessment, Opihi, Taup??.

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  • Cobalt(III) Complexes Containing Analogues of Bioactive Anticancer Compounds

    Mistry, Meet (2016)

    Doctoral thesis
    The University of Auckland Library

    Since the discovery of cisplatin as a potent anticancer agent, transition metal complexes have played a significant role in the development of new anticancer compounds. The anticancer potential of cobalt complexes has been extensively studied over the last three decades, and much time has been devoted to understanding their mechanisms of action. After understanding the Co(III)/Co(II) reduction activation mechanism, several Co(III) complexes of bioactive anticancer agents have been investigated as potential hypoxia activated prodrugs. Furthermore, after the initial use of nitrogen mustard, several bioactive compounds and their analogues have been investigated as ligands to develop hypoxia activated Co(III) complexes. This thesis describes syntheses and characterisation of Co(III) complexes that have been designed using structural analogues of bioactive anticancer compounds. Chapter 1 gives an overview of the prodrug strategy in cancer therapy, prodrug design using a trigger and an effector unit, and different mechanisms for prodrug activation. Several examples of Co(III) complexes are given, which have been investigated as potential prodrugs to target tumour hypoxia. There are three different parts to this research. Chapters 2, 3 and 4 describe the syntheses and characterisation of Co(III) complexes designed using ligands, which are structural analogues of bioactive anticancer compounds. Chapter 2 describes syntheses of dipeptide analogues of bortezomib, a proteasome inhibitor that is currently being used for the treatment for multiple myeloma. The Co(III)-dipeptide complexes were also analysed for their possible use as hypoxia activated prodrugs in Chapter 2. Chapter 3 includes the continuation to the previous investigation by Ware et al. on Co(III)-cyclen complex using 8-hydroxyquinoline (8HQ) as a model cytotoxin. Efforts were made to establish a synthetic route to introduce a porphyrin derivative into prodrug design, with the aim of improving tumour cell targeting properties of the prodrug complex. Chapter 4 describes syntheses of two polypyridyl carboxamide ligands, PDPA and MID(AMP)2, and syntheses of their Co(III) complexes. PDPA and MID(AMP)2, are structural analogues of PMAH, Py3PH2, which are carboxamide ligands containing a similar metal-binding domain as bleomycins. The experimental procedures are detailed in Chapter 5.

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  • Task Complexity, Affective Factors, and Pre-task Planning: Effects on L2 Writing Production

    Rahimi, Muhammad (2016)

    Doctoral thesis
    The University of Auckland Library

    Two studies were conducted to investigate the role of task complexity and affective factors, and task complexity and pre-task planning conditions, in L2 writing production. Two writing tasks with varying degrees of complexity in relation to the reasoning demands and the number of elements were designed and validated. Upperintermediate English language learners were invited to participate in this study on a voluntary basis. In Study 1, one group of the learners (n = 60) performed a simple and a complex version of an argumentative writing task, and their writing production was measured in terms of syntactic complexity, accuracy, lexical complexity, and fluency (CALF), as well as the organisation, content, and overall written text quality. In Study 2, one group of the learners (n = 40) performed the simple and complex tasks under 10-minute pre-task planning and another group (n = 40) under no-pre-task planning conditions. The learners' writing production was compared using the same measures employed in Study 1. In Study 1, increasing task complexity led to a significant desirable change in one dimension of both syntactic and lexical complexity, had a significant adverse effect on accuracy and fluency, and led to the enhancement of L2 content, organisation, and writing quality. As regards the mediating role of motivation and anxiety, significant moderate negative associations were found between some dimensions of maladaptive approaches to learning and some measures of L2 writing production in the complex writing task performance. Conversely, significant moderate positive correlations were found between some aspects of adaptive approaches to learning and some measures of L2 writing production in the complex L2 writing task performance. In Study 2, a similar trend was found for the effect of increasing task complexity along the level of reasoning and the number of elements as in Study 1. The impact of 10-minute pre-task planning on L2 writing production was significantly favourable for one dimension of syntactic complexity and fluency. There were no significant effects on accuracy and lexical complexity. Nonetheless, significant positive changes for content, organisation, and writing quality were found. The findings lend partial support to the Cognition Hypothesis and the Trade-Off Hypothesis; other theoretical, methodological, and pedagogical implications are also discussed.

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  • Practical Output Regulation of Non-Minimum Phase Nonlinear Systems

    Postelnik, Leron (2016)

    Doctoral thesis
    The University of Auckland Library

    This thesis focuses on the output regulation of control-affine time-invariant non-minimum phase nonlinear systems, specifically regarding the output tracking of time-varying signals in the presence of system uncertainty. Much of the published output regulation theory for this class of system faces significant barriers to practical application. The more practical approaches, which are not limited by these same barriers, have seen limited application to practical systems within the literature. Three such approaches ??? the kth-order approximate output regulator, the kth-order robust output regulator, and the stable system centre based sliding mode control approach ??? are herein applied to two case studies in order to both provide additional examples of their application to physically meaningful systems and to gain further insight into the strengths and weaknesses of each approach in regard to practical application e.g. when facing various forms of system uncertainty. Furthermore, a novel "approximate stable system centre" approach was developed and shown to provide improved tracking performance over the standard stable system centre approach under certain conditions. The two case studies considered are the spherical inverted pendulum, which is a more complex system compared to the standard SISO inverted pendulum on a cart commonly used a benchmark nonlinear system, and the two-wheeled balancing robot, which serves as a direct practical application in the area of mobile robotics. Simulations were conducted for the 2D position control of the spherical inverted pendulum and the 2D forward and yaw speed control of the two-wheeled robot in the presence of parametric and unstructured uncertainty. Measurement noise and delay was additionally considered in the two-wheeled robot simulations. Experimental testing was also conducted for the straight-line position control of the two-wheeled robot. Overall, the kth-order robust output regulator provided the most accurate steady state tracking under most conditions considered, but suffered from poor transient response. The kth-order approximate output regulator gave the fastest transient response, but only provided acceptable steady state performance under low levels of uncertainty. The approximate stable system centre approach provided a well-balanced performance under most conditions, but was the most sensitive to the presence of system delays due to use of the sliding mode controller.

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  • Pilvax: a novel peptide antigen delivery strategy for the generation of vaccines

    Wagachchi, Dasun (2016)

    Doctoral thesis
    The University of Auckland Library

    There has been a shift in vaccine development from being based on killed or attenuated whole microorganisms to smaller, more specific subunit vaccines, including peptides. However, peptides by themselves are often poorly immunogenic, necessitating the need for an adjuvant or a specialised delivery system. A novel peptide delivery strategy, Pilvax, was developed in this thesis by expressing peptides within the serotype M1 group A streptococcus (GAS) pilus structure on the surface of Lactococcus lactis. In GAS, each fully assembled pilus structure consists of approximately 50-100 Spy0128 pilin subunits that are covalently linked by isopeptide bond formation. Genetically engineering a peptide into the Spy0128 subunit will result in the expression of hundreds of repeated copies of the peptide on a single pilus and thousands of copies across the surface of the bacterium. The complete GAS pilus structure can be expressed and assembled on the surface of L. lactis, a non-pathogenic bacterium which has generally recognised as safe (GRAS) status. L. lactis is a promising antigen delivery vehicle, having been used to deliver numerous vaccine candidate antigens to both mucosal and systemic sites. Six loop regions and the N-terminus of the Spy0128 pilin were selected as possible sites where a peptide could be engineered into. However, peptides could only be engineered into two of the loop regions without affecting the polymerisation of the pilus on the surface of L. lactis. To show proof of principle, a peptide consisting of ovalbumin from positions 323 to 339 (OVA323-339) was engineered between the ??E and ??F loop of Spy0128 and the peptide-linked pilus was expressed on the surface of L. lactis. Incorporation of OVA323-339 into the pilus structure was demonstrated by Western blot analyses of cell wall proteins and by flow cytometry. Intranasal immunisation of mice with L. lactis expressing pilus-linked OVA323-339 results in production of both a systemic and mucosal antibody response against ovalbumin. The feasibility of using Pilvax to deliver a structural epitope was then investigated. The J14 peptide, a chimeric peptide derived from the carboxy-terminal C-repeat region of the GAS M protein, was chosen to be engineered into Pilvax. The peptide contains a conformationally restricted B cell epitope fused to coil-promoting moieties from the yeast GCN4 protein to maintain the original coiled-coil structure. The J14 peptide engineered between the ??E and ??F loop of Spy0128 showed incorporation of J14 into pili, expressed on the surface of L. lactis, as demonstrated by Western blot analyses of cell wall proteins. However, intranasal immunisation of mice with L. lactis expressing pilus-linked J14 only induced a weak J14-specific antibody response and the antibodies elicited could not recognise and bind the native M protein. This suggests that the alpha-helical conformation of J14, required for the peptide to be an effective vaccine candidate, is disrupted when it is engineered into a loop region of Spy0128. Thus, Pilvax may provide an alternative strategy to allow safe and effective delivery of vaccine peptides to mucosal sites, but may be limited to conformation-independent peptides.

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  • The Impact of a Medical Curriculum on Motivation and Well-being Among Medical Students

    Lyndon, Mataroria (2016)

    Doctoral thesis
    The University of Auckland Library

    Aim The aim of this thesis was to determine the impact of critical aspects of a medical curriculum on motivation and well-being, and how these constructs affect academic achievement among medical students. Method A multi-methods approach incorporating systematic review and quantitative and qualitative studies was undertaken. More specifically, this approach included reviewing the literature of motivation and well-being among medical students; exploring motivation and well-being by year level of a curriculum and admissions criteria (qualitative study); evaluating the effect of a medical curriculum on motivation and well-being over time (longitudinal study); examining motivation and well-being among ethnic groups (cross-sectional study); evaluating a change of medical curriculum on motivation and well-being (cross-sectional comparative study); and investigating associations between motivation, well-being and academic achievement (person-oriented approach). Results The systematic review found valuable associations between the constructs of motivation and well-being that were moderated by demographic and curriculum variables. Furthermore, it indicated a relationship may exist between motivation, well-being and academic achievement. The qualitative study found clear differences in student expression between admissions criteria and year level, suggesting that the curriculum and sociocultural influences are mediators of motivation and wellbeing. Furthermore, changes in motivation and well-being occur longitudinally, which differ by year level of the curriculum and admissions criteria. The cross-sectional study found differences in motivation and well-being among indigenous and ethnic minority medical students. The comparative cohort study found no significant differences in motivation and well-being between cohorts of medical students under traditional and revised curricula; however, differences were found among students in their clinical years of training. Finally, associations between motivation and wellbeing were observed, which had a relationship with academic achievement over time. Conclusion A medical curriculum has an impact on motivation and well-being, which differs by year level, admissions criteria, and ethnicity. Furthermore, a relationship exists between motivation and well-being, and academic achievement. These findings have implications for student recruitment and retention, student equity and curriculum development, and highlights the challenges of facilitating learning environments and curricula that support optimal forms of motivation and enhance well-being for all students.

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  • A Study in the Performance of Sediment Retention Ponds

    Farjood, Arash (2016)

    Doctoral thesis
    The University of Auckland Library

    This thesis describes a laboratory experimental study to investigate performance of a scale model of a sediment retention pond, with the aim of improving the understanding of the effect of physical design features on its hydraulic performance and sediment removal performance. The experiments were conducted using a 1:10 scale model of a field sediment retention pond. Several configurations of the model pond with different widths of inlet, design of outlet, and location, number and type of baffles were examined. All of the experiments were conducted at steady state condition with fixed flow rates. Tracer experiments, using Rhodamine WT tracer dye, formed the majority of the experiments, from which residence time distribution curves (RTDs) were obtained and analysed. In addition, the tracer dye was visually observed to identify the zones of short-circuiting. Sediment removal performance was evaluated for a number of pond configurations, by measuring water turbidity at the outlet. The turbidity was caused by addition of a representative sediment (silica flour) to the pond. Velocity fields were also measured for inspecting the effect of spatial velocity variations on sediment removal performance. In addition to physical modelling, a CFD technique was employed for numerical investigation of pond configurations with different length-to-width ratio and bank slopes. The results showed that reducing the width of the inlet (to 85% of pond???s width) to avoid the shallow water over the sloping side walls, and modifying the outlet to avoid disrupting the flow streamlines, both improved hydraulic performance. Installation of submerged solid baffles, and different types of porous baffles, further increased the pond???s hydraulic performance, albeit to different degrees. Sediment removal performance was also increased when baffles were incorporated. Comparison of hydraulic performance and sediment removal performance indicated a strong correlation between these two measures. In addition, the data collected from the tracer experiments were scrutinised, and a new index was developed for quantification of the hydraulic performance of ponds and wetlands. The results of CFD modelling showed that pond configurations with aspect ratio of 5:1 or larger, and (for a given aspect ratio) with a bank slope of 2:1, had higher hydraulic performances. This research is the first to extensively investigate details and locations of baffles for improving hydraulic performance of sediment retention ponds. It can provide useful information for improving the performance of ponds by altering their design. In addition, a new index was developed for ponds and wetlands, which can contribute to a more enhanced analysis of hydraulic performance in ponds and wetlands of different layouts and configurations.

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  • The genetic determinants of vigour control and precocity by pear (Pyrus communis L.) rootstocks

    Knaebel, Mareike (2016)

    Doctoral thesis
    The University of Auckland Library

    The growth habits of fruit trees have a significant influence on their efficiency in commercial production. Small tree stature allows high-density plantings and therefore more efficient land use, while minimising the length of the trees??? juvenile period means the orchard becomes profitable sooner. Vigour control and precocity are therefore two of the most important traits in commercial pear production. Dwarfing rootstocks are used to reduce the size of the scion and enable precocious flowering in many perennial cultivars. Currently there is a lack of Pyrus rootstocks that are vigour-controlling and precocity-inducing. The development of such a rootstock is a major focus in pear rootstock breeding. Marker assisted selection (MAS) could help to shorten this time consuming and costly breeding process. The aim of this PhD project was to examine the genetic determinants of vigour control and early flowering conferred to a scion by Pyrus rootstocks. A segregating population of 421 F1 seedlings from a P. communis ???Old Home??? x ???Louise Bonne de Jersey??? (OHxLBJ) cross was grafted with clonal ???Doyenne du Comice??? scions and used as the core experimental material for this project. High-density genetic maps were constructed for pear using two different high throughput genotyping tools, the Infinium?? II 9K apple/pear SNP array and the genotyping-by-sequencing (GBS) approach. QTLs influencing expression of scion vigour and precocity were detected on linkage groups (LG)5 and LG6 of OH and LG6 of LBJ. The LG5 QTL was found in the same genomic region as the dwarfing (DW1) QTL identified in the ???M9??? apple rootstock. The alignment of the QTL loci of apple and pear showed a high synteny between both loci and may help to identify candidate genes in both genera. The ease of vegetative propagation, a crucial trait for rootstock breeding, was assessed in rooting experiments and small effect QTLs were identified. These results will help to understand the genetic control of vegetative propagation in pear, and may assist in developing markers for MAS for this complex trait.

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  • A law and development perspective on services liberalisation in the Pacific Island Countries with particular reference to tourism

    Chan, Yok (2016)

    Doctoral thesis
    The University of Auckland Library

    Pacific island governments embraced the concept of reciprocal free trade agreements in the late 1990s in response to shifts in their historical relationships with their major donors and the ascendancy of neoliberal globalisation as the dominant model of development. Since then, they have placed a great deal of faith in this model as a pathway to sustainable development to generate economic growth, employment and as a means to achieve development goals such as poverty alleviation. The thesis examines whether international economic treaties and trade rules constrain development strategies and policy choices of the fourteen Pacific Island Countries (PICs). The thesis focuses on services liberalisation with special reference to tourism services, using as its analytical framework the theory of ???Three Moments??? in law and development doctrine, as advanced in 2006 by Trubek and Santos in The New Law and Economic Development: A Critical Appraisal. Using this framework, it examines the interface of two competing paradigms of development - neoliberalism and the Right to Development. The thesis also explores how the liberalisation efforts on trade in services have been rationalised and advanced at the international level through the General Agreement on Trade in Services (GATS) and at the regional level through the negotiations of regional free trade agreements such as the Economic Partnership Agreement (EPA) and the Pacific Agreement on Closer Economic Relations (PACER Plus), and the implications for policy and regulatory decisions at the national level in the PICs, especially those who are members of the World Trade Organization. The thesis supports two main conclusions. First, the prevailing neoliberal model of development, embodied in the Second Moment of Law and Development, is not appropriate for the PICs in their pursuit of sustainable development. Second, there are signs of a possible shift towards a Third Moment in the region, but this potential is constrained by the instruments of international economic law, as well as political pressure from the PICs??? key trading partners who are also major donors.

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  • Regulatory and Non-Regulatory Influential Factors for Earnings Management by Real Estate Investment Trusts

    Liang, Jian (2016)

    Doctoral thesis
    The University of Auckland Library

    This research investigates how non-regulatory, and regulatory factors influence the Earnings Management (EM) by Real Estate Investment Trusts (REITs). The regulatory factors pertain to the REITs??? regulatory regimes. The non-regulatory factors include the composition of property portfolios, the choice of the security structure, the 2007 global financial crises (GFC), EM persistence and the trade-off between different EM measurements. This study is based on quantitative methodology, and it uses an unbalanced panel database with information of REITs from major REIT markets from 2000 to 2013. This research extends and modifies models from existing literature to estimate the EM measurements of REITs. Static and dynamic panel data models are used in empirical tests. Treatment effect estimators are employed to analyse the impact of security structure choice and REITs??? conversion on EM. This research provides the following findings: (1) The variances of the proportions of different types of property in the property portfolio held by New Zealand Listed property portfolios have a significant impact on the magnitudes of using various EM approaches. (2) The 2007 GFC has changed the EM behaviour of the U.S equity REITs. (3) Compared to unstapled Australian REITs, stapled Australian REITs engage in EM activities in a greater magnitude. (4) The measurements of EM activities in the current accounting period react to their own value in the previous accounting period and the measurements of other EM activities in the previous accounting period in different manners. (5) Listed real estate corporations change their EM behaviour to prepare for their REIT conversion. Listed real estate corporations are different from REITs in regard to their EM behaviour. (6) The magnitudes of accrual EM activities are found to be positively correlated with the abnormal volatilities of the leverage ratio and the dividend pay-out ratio. (7) The incentive for REITs to comply with the requirements for leverage ratio and dividend pay-out ratio significantly impacts the magnitudes of EM measurement. These results contribute to the understanding of information asymmetry, efficient market hypothesis and corporate governance in the context of REITs. The findings enhance investors??? and policymakers??? knowledge of the disclosure of financial information for REITs and may assist in improving transparency in REIT markets.

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  • Robust Control of Nonlinear Systems: Sliding mode and Non-monotonic Approaches

    Nasiri Minab, Alireza (2016)

    Doctoral thesis
    The University of Auckland Library

    The field of robust controller design for nonlinear systems has been an important area of research in the control community over the past few decades. Lyapunov based control design methods have developed into an established class of procedures for robust control design. This dissertation initially applies the standard Lyapunov function approach to design an adaptive sliding mode controller (SMC). Next, the non-monotonic Lyapunov approach, which is a variant of the classical Lyapunov approach, is utilised to design a robust controller for discrete-time nonlinear systems represented by a Takagi-Sugeno (T-S) fuzzy model. An adaptive scheme of designing SMC for the affine class of multiple input multiple output (MIMO) nonlinear systems with norm bounded uncertainties is proposed during the first stage of the research. The proposed adaptive SMC does not require a priori knowledge of the bounds of uncertainties and therefore offers significant advantages over non-adaptive schemes of SMC design. Next, this controller is developed to be fault tolerant for actuator faults. The actuator fault is represented by a multiplicative factor of the control signal which reflects the loss of actuator effectiveness. The design of the controller is based on the assumption that the maximum loss level of actuator effectiveness is known. The effectiveness of the proposed controllers is demonstrated considering a two-link robot manipulator. The stability analysis and stabilisation of discrete-time nonlinear systems described by T-S fuzzy models are investigated and new design procedures are proposed in the second stage of this thesis. The stability analysis of T-S fuzzy models and subsequently the controller design are often carried out through the Lyapunov method. This leads to some inherent inequalities in which the nonlinear membership functions are excluded from the final analysis and synthesis conditions. As a result the stability conditions, which are often constructed in the form of linear matrix inequalities (LMIs), become only sufficient (conservative). To reduce this conservatism, the assumption of monotonic decrease of Lyapunov function has been relaxed giving a new approach to the control design known as the non-monotonic Lyapunov approach, where the Lyapunov function is no longer required to decrease in each successive time step (i.e., Vt+1 < Vt ). Instead, small local growth is allowed but ultimately it converges to zero. In recent years, various researchers have used the k-samples variations approach (i.e., Vt+k

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  • Effect of Statins on the Surgical Stress Response in Colorectal Surgery

    Singh, Primal (2016)

    Doctoral thesis
    The University of Auckland Library

    Major colorectal surgery leads to a significant physiological stress response that is associated with postoperative morbidity and prolonged patient recovery. Statins are a widely used class of cholesterollowering drugs with useful pleiotropic effects that are relevant to abdominal surgery. Despite considerable experimental evidence, the clinical evidence of their benefits in the setting of abdominal surgery is limited to retrospective and observational studies. The aims of this thesis was to examine the correlation of the surgical stress response to postoperative morbidity following major colorectal surgery and explore the novel concept of whether statins can attenuate this response and improve clinical outcomes after surgery. Chapter one discusses the basis of the surgical stress response, introduces the concept of statins and presents the evidence demonstrating their surgically relevant benefits. Chapter two explores the association between postoperative inflammation and morbidity after colorectal surgery by presenting a meta-analysis which shows C-reactive protein levels in the early postoperative period correlate with the development of anastomotic leakage and have a useful negative predictive value. Chapter three presents a retrospective study which demonstrates the relationship between patient-reported functional recovery and morbidity following colonic surgery using the surgical recovery score questionnaire and shows it closely correlates with postoperative complications and their severity. In chapter four, a retrospective review of patients undergoing elective colectomy is presented and shows patients on statins during the perioperative period achieved equivalent outcomes for complications and functional recovery despite significantly higher perioperative risk and had a significantly lower rate of anastomotic leak. Chapter five is a systematic review which critically appraises the available clinical studies on the use of statins in abdominal surgery and shows the various benefits demonstrated, particularly for inflammatory and infective outcomes. This leads to a placebo-controlled, randomised clinical trial presented in chapter six which shows that perioperative oral simvastatin therapy in patients undergoing major elective colorectal surgery leads to a significant reduction in inflammatory markers in the early postoperative period but no difference in complications or functional recovery. Therefore, the addition of perioperative simvastatin therapy cannot be recommended as a routine for patients undergoing major elective colorectal surgery.

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  • Sense Shaping Place: Interaction of Planning Actor???s Values in Social- Ecological Resilience: Case Study of Urbanizing Coastal Rural Communities in Pontian, Malaysia.

    Azizui, Muhammad Farid Azizul (2016)

    Doctoral thesis
    The University of Auckland Library

    Drawing on the literature from bioregional planning that encapsulates theories on place, stewardship and conservation, this study explores the dynamics in the interaction between the various planning actors and how this contributes to the resilience of socio-ecological systems (SESs). Using the urbanizing coastal rural communities of Pontian as a case study, I have employed a mixed-methods approach to examine the sense of place held by three distinct planning actor groups involved in the local land use planning activities. The groups are Local Active Community, Civic and Institution, and Environmental and Cultural Advocacy. I analyzed qualitative interviews as well as quantitative surveys to elicit the sense of place structure across groups, the relationship between structures and stewardship attitudes and behaviors, and examined how these characteristics might shape the trajectories of landscape change. This study extends the examination of the people-place relationship and its impacts on resilience, as prior place research has focused on sense of place at the individual level but is limited when assessing group level outcomes. A number of distinctions were found. The sense of place structure was found to be comprised of four traits; place dependence, place identity, place attachment and community attachment. The latter appeared to emerge separately. The structure patterns were similar across groups in the survey, however, a more nuanced description in the interviews revealed that the place structure for each of the first two groups emphasized social and community aspect of place, while the latter emphasized functional aspect of place dependency. The relationship between sense of place, stewardship and visions was far more complex than reported in the literature, where stewardship was divided between affirmative and non-supportive attitudes towards rural landscape change. In contrast, in this study ???place dependence??? correlated with ???concerned but supporting attitude??? and was characteristic of the first two groups. The qualitative findings specified that this variability between groups is linked to specific worldviews and motivations and visions that are layered in social, cultural and political backgrounds. Multiple pathways to sustainability were observed from different place conception and attitudes among the groups, based on analysis that is grounded in a model of SES and resilience. The insights were critiqued in a bioregional planning context and justify further research on sense of place as an integrative concept for understanding societal impacts on ecosystems in a complex, rapidly changing world. Keywords: bioregional planning, sense of place, environmental stewardship, socialecological resilience, landscape change.

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  • Biogeography and Taxonomy of Razor Clams (Bivalvia: Solenidae)

    Saeedi, Hanieh (2016)

    Doctoral thesis
    The University of Auckland Library

    This dissertation describes the taxonomy, biodiversity, biogeography, and current and future predicted distributions of deep-burrowing razor clams of the family Solenidae. Solen species have often been misidentified due to the high similarity in their shell morphology. Principal component analysis (PCA) and discriminant analysis showed that species could not be separated based on the morphometric measurements of the anterior adductor scar length, ligament length, and shell width to shell length ratio. Thus, geometric shape analysis, and DNA-barcoding techniques are recommended to further study the phylogeny and evolution of Solenidae. A bimodal global species richness pattern was discovered resulting from a higher Solenidae species richness at the edges of the tropics than near the equator. This contrasts with the unimodal latitudinal species richness pattern reported so far in most marine taxa with high species richness in the Tropics. There was a non-linear relationship between the Solenidae species richness and mean sea surface temperature values in each 5?? latitude band. The mid-latitude peaks in richness support the hypothesis of speciation in response to temperature variation near the edges of the tropics. Cluster analysis of Solenidae species distribution showed 13 biogeographic regions with no species occurring in polar regions. Most (50-100%) of the species were endemic to, i.e. only occurred in their geographic regions. Suitable environments for Solenidae species were predicted using species distribution modelling techniques based on environmental factors. Maximum Entropy (MaxEnt) was applied to predict the distribution of Solenidae species at present and thus the species??? potential geographic ranges under future climate change scenarios. Distance to land and depth were the most important variables in determining Solenidae distribution. Species distribution models predicted that all species in the northern hemisphere would shift northward, and southern species southward, under future climate change. Models also predicted that 50% of the species would expand their distribution ranges, about 28% would not change their distribution, and about 22% would shrink their distribution ranges under future climate warming. Climate change will likely lead to distribution range changes in Solenidae species richness mostly in the southern hemisphere, especially in Australia.

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  • The Effect of Musical Aptitude: Perceiving and Producing Mandarin Lexical Tones By Non-Native Speakers of Chinese

    Zhu, Jingzhi (2016)

    Doctoral thesis
    The University of Auckland Library

    This study explores the effect of musical aptitude as a combination of innate musical aptitude and learned/trained musical aptitude in tonal perception and tonal production by non-native speakers of Chinese. The study aims to discover whether the musical aptitude of non-native speakers of Chinese helps in their perception and production of Mandarin lexical tones at different stages of learning. Mandarin uses tones to lexically distinguish word meanings, and therefore learning these tones is essential to communication in the language. A number of studies have found that those learning Mandarin as a foreign language have difficulty in perceiving and producing Mandarin lexical tones (Klein, Zatorre, Mikner & Zhao, 2001; Wang et al., 2001a; 2003; Lee et al., 2009). In order to tackle this problem and therefore improve Mandarin learners??? learning, researchers have attempted to detect the source of this difficulty. Seven factors were identified, three linguistic factors and four sociolinguistic factors. The former included the categorical nature of tone, the phonetic cues for tone, and the context-dependent nature of tone sandhi; the latter factors included the learners??? language experience in the form of bilingualism, the learner???s age, foreign language anxiety and the impact of gender (Chao, 1968; Brown, 1980; Hassler et al., 1985; Xu, 1997; Peretz & Coltheart, 2003; Wee, 2008). Among the seven factors, the phonetic cues of Mandarin lexical tones and learners??? learning experience in the form of bilingualism remained underspecified in prior studies, and hence became two of the research aims in this study. The findings of the small body of research into another underspecified factor affecting learners??? perception and production of Mandarin lexical tones, learners??? musical aptitude, have been inconsistent: some investigators found little or no relationship between musical aptitude and L2 learning of tone (e.g. Peoppel, 2001; Anvari et al., 2002), while other investigators have found such a relationship to exist (e.g. Zatorre et al., 2002; Slev & Miyake, 2006; Wong et al., 2007). In order to provide more conclusive evidence in regard to the three above mentioned underspecified factors affecting learners??? perception and production of Mandarin lexical tones, the current study provides a more rigorous and precise research design than those adopted in previous studies. During the first stage of the longitudinal study forty-five non-native speakers of Chinese enrolled in the Chinese Stage I course at the University of Auckland were administered a questionnaire, and then tested using an innate MA test, a Mandarin lexical tone listening test (for perception), and a Mandarin lexical tone speaking test (for production). The eleven participants who continued into the later stage of the study again took each of these tests twelve weeks later at the end of their first semester of study. A comparison of the findings of the tests revealed that musical aptitude, defined as a combination of innate musical aptitude and learned/trained musical aptitude, did help non-native speakers of Chinese in their perception and production of Mandarin lexical tones in the early stage of their learning. Particularly, pitch in musical aptitude provided the most advantage in learners??? tonal perception, and melody in musical aptitude provided the most advantage in their tonal production. Concurrently, in addition to musical aptitude, learners??? language experience in form of bilingualism also played a role in their tonal perception and production. However, the findings also revealed that as learners??? tonal training in the formal classroom setting increased, the impact of observed musical aptitude on learners??? tonal perception and production became less over time. These findings overall indicate that while musical aptitude may help non-native speakers of Chinese in their perception and production of Mandarin lexical tones during the early stage of their learning, it may not necessarily be as important during the later stages of their learning. This thesis concludes with important insights and significant theoretical, methodological, and pedagogical contributions from this research on the relationship between musical aptitude and Mandarin tones.

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  • Metabolomics and proteomics investigations of Alzheimer???s disease and related conditions

    Xu, Jingshu (2016)

    Doctoral thesis
    The University of Auckland Library

    Alzheimer???s disease (AD) causes the commonest form of dementia, and remains the largest unmet medical need in neurology. The cause of AD is largely unknown and to date, there are no treatments with proven disease-modifying actions. Substantial evidence has accumulated to support an important association between type-2-diabetes (T2D) and AD. Specifically, the vasculopathy aspects of T2D and AD have gained significant scientific attention, with a potential link being atherosclerosis. This study aimed to improve understanding of the molecular basis of AD pathogenesis, with focus on vascular mechanisms. Case-control studies were performed in ex-vivo rabbit aortic tissue, and postmortem brain tissue from patients. Specifically, we aimed to generate a detailed molecular profile representative of pathogenetic processes in aortic tissue from a rabbit model of atherosclerosis, and brain from AD patients. Furthermore, we aimed to measure and compare molecular changes in seven structurally and functionally distinct brain regions, to improve understanding of disease distribution in the human brain. I performed parallel proteomic analyses and metabolic profiling studies: target tissues were analysed by iTRAQ-proteomics and tissue metabolites profiled by gas-chromatography-mass-spectrometry and liquid-chromatography-mass-spectrometry. We derived a detailed description of molecular changes in human AD brain at both protein and metabolite levels, and generated quantitative protein and metabolite profiles from seven distinct brain regions. AD brain exhibited clear evidence of global perturbations in phospholipid content and defects in energy-producing mechanisms, the latter characterised by impaired glycolytic pathway and TCA cycle enzymes and metabolites, with concomitant activation of the pentose-phosphate and polyol pathways. Compared to severely affected brain regions (hippocampus and entorhinal cortex), the least affected brain region (cerebellum) exhibited molecular signatures indicative of earlier disease processes and activation of molecular defence mechanisms: these included better-preserved systems for protein folding, protein degradation, and A??-clearance, and lesser activation of the immune response and oxidative phosphorylation. I concluded that: accumulation of free glucose, sorbitol and fructose in AD brain is a probable cause of decreased cerebral glucose uptake as observed in patients; glycosylated proteins/lipids, interacting with relevant receptors may promote vasculopathy in atherosclerosis, T2D and AD; and, in the latter, different brain regions undergo molecular damage at different rates.

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