939 results for Doctoral, 2012

  • An Approach to Embedding ITSs into Existing Systems

    Amalathas, Sagaya Sabestinal (2012)

    Doctoral thesis
    University of Canterbury Library

    Intelligent Tutoring Systems (ITSs) have proven their effectiveness in many domains, but very few attempts have been made to embed them with existing systems. This area of research has a lot of potential in providing life-long learning and work place training. This PhD project makes several significant contributions. This is the first attempt to embed a Constraint-Based Tutor (CBT) with an existing system, in order to investigate the benefits of providing on-the-job training. We also propose a framework for embedded ITSs, and develop DM-Tutor (Decision-Making Tutor) embedded with the MIS for palm oil. DM-Tutor is the first ITS for the domain of oil palm plantation decision making, and was developed in the ASPIRE authoring system. Our hypothesis was that DM-Tutor embedded with the MIS for palm oil would provide effective instruction and training for oil palm plantation decision making. We also wanted to investigate the role of feedback messages in helping to provide effective training.

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  • Foraging behaviour of female Weddell seals (Leptonychotes weddellii) during lactation: new insights from dietary biomarkers

    Lenky, Crystal (2012)

    Doctoral thesis
    University of Canterbury Library

    Despite extensive studies on Weddell seals (Leptonychotes weddellii) in McMurdo Sound since the 1960s, uncertainty still remains regarding female foraging habits during the lactation period. Based on their large body mass at the start of lactation and large relative mass loss at the end, the current hypothesis is that Weddell seals fast or feed to a neglible extent during lactation. However, this hypothesis has not been fully tested to date, as evidence for foraging is indirect and is based primarily on dive behaviour. The work presented in this thesis describes the development of a new dietary method, the biomarker method, and its application for studying the foraging behaviour of female Weddell seals during lactation. Biomarkers were used to (1) monitor the onset of feeding in individual animals, and (2) determine what prey females were feeding on using characteristic/taxon-specific biomarker patterns. Proton nuclear magnetic resonance spectroscopy (1H NMR) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays were developed to detect and quantify dietary biomarkers in biological samples, mainly tissues, serum and plasma. Trimethylamine N-oxide, arsenobetaine, dimethylsulfoniopropionate, homarine and glycine betaine were first measured in thirty-three prey and potential prey species of Weddell seals collected from the Ross Sea and McMurdo Sound regions of Antarctica. These same compounds were then measured in the plasma of twelve female Weddell seals over the lactation period at the Hutton Cliffs seal colony, McMurdo Sound in 2006. Time-depth recorders monitored seal dive activity over the same period. The data obtained from both NMR and LC-MS/MS assays showed that biomarkers in Antarctic species varied both in content and concentration. The compound homarine, which occurs primarily in cephalopods, is suitable for distinguishing between major food groups of known prey of Weddell seals (i.e., fishes versus cephalopods). DMSP, a compound that occurs primarily in fish common in McMurdo Sound (e.g., Trematomus bernacchii and Pagothenia borchgrevinki) but not in significant amounts in Dissostichus mawsoni or Pleuragramma antarcticum, two main prey items for Weddell seals, may also be a suitable biomarker for distinguishing between major and minor prey types. The detection of plasma TMAO, AsB and homarine indicated that 75% of Weddell seals studied fed during lactation. The presence of these three compounds indicates the seals were preying upon a combination of fish and cephalopods. Two lactating females started foraging as early as 9 to 12 days postpartum and elevated biomarker levels were concurrent with increased dive activity. The onset of foraging and dive behaviour amongst individuals was highly variable; however, the results suggests that the number of females who feed during lactation may be more prevalent and initiated at an earlier stage than previously thought. This may have implications for future reproductive success given effects of climate change on sea ice abundance and resource availability. Overall, the work presented in this thesis provides new insights into the foraging behaviour of female Weddell seals during lactation and has added to the current knowledge of the biomarker distribution within the Antarctic ecosystem.

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  • Ameliorating Systematic Errors in Full-Field AMCW Lidar

    Godbaz, John Peter (2012)

    Doctoral thesis
    University of Waikato

    This thesis presents an analysis of systematic error in full-field amplitude modulated continuous wave range-imaging systems. The primary focus is on the mixed pixel/multipath interference problem, with digressions into defocus restoration, irregular phase sampling and the systematic phase perturbations introduced by random noise. As an integral part of the thesis, a detailed model of signal formation is developed, that models noise statistics not included in previously reported models. Prior work on the mixed pixel/multipath interference problem has been limited to detection and removal of perturbed measurements or partial amelioration using spatial information, such as knowledge of the spatially variant scattering point spread function, or raytracing using an assumption of Lambertian reflection. Furthermore, prior art has only used AMCW range measurements at a single modulation frequency. In contrast, in this thesis, by taking multiple measurements at different modulation frequencies with known ratio-of-integers frequency relationships, a range of new closed-form and lookup table based inversion and bounding methods are explored. These methods include: sparse spike train deconvolution based multiple return separation, a closed-form inverse using attenuation ratios and a normalisation based lookup table method that uses a new property we term the characteristic measurement. Other approaches include a Cauchy distribution based model for backscattering sources which are range-diffuse, like fog or hair. Novel bounding methods are developed using the characteristic measurement and attenuation ratios on relative intensity, relative phase and phase perturbutation. A detailed noise and performance analysis is performed of the characteristic measurement lookup table method and the bounding methods using simulated data. Experiments are performed using the University of Waikato Heterodyne range-imager, the Canesta XZ-422 and the Mesa Imaging Swissranger 4000 in order to demonstrate the performance of the lookup table method. The lookup table method is found to provide an order of magnitude improvement in ranging accuracy, albeit at the expense of ranging precision.

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  • Investigation into the functional nature of Frc locus conditioning fructan levels in onion

    Revanna, Roopashree (2012)

    Doctoral thesis
    University of Canterbury Library

    Frc, a major gene on chromosome 8, conditions fructan levels in onions (Allium cepa L). In order to assist genetic dissection of this locus, this study aimed to determine the factors influencing varying fructan levels in high- and low-fructan genotypes. Mapping families were developed and analysed to study the genetic architecture for the fructan trait, and to check the association of the identified variables with the Frc locus. To facilitate reliable and practicable sugar assays in onions, a newly-adapted high-throughput microplate enzymatic assay was validated in this study. The reliability of using leaf sugars as a representative of bulb sugars in a mapping population was studied. Microplate enzymatic sugar assays were carried out on a segregating onion cross to validate the use of maltases in sugar analysis, and the results obtained were validated against HPLC-PAD. Sucrose measured in microplates employing maltases as the hydrolytic enzyme was in agreement with HPLC-PAD results. Maltase enzymes specifically hydrolysed sucrose in onions, providing an alternate tool in place of expensive sugar assay kits. Use of the microplate-enzymatic assay provided a rapid, cheap and practicable method for sugar analysis in onion. Differences in carbohydrate content, sucrose metabolising enzyme activities and their expression levels were monitored in developing leaf blades and leaf bases of four high- and four low-fructan genotypes. The variation in fructan accumulation between high- and low-fructan genotypes was due to the variation in sucrose metabolism. SPS expression and activity did not vary between high- and low-fructan genotypes. Acid invertase and 1-SST showed significant variation in their activities between the two fructan groups. Post-transcriptional and translational regulation of AI and 1-SST respectively, are suggested. Mapping populations analysed for non-structural carbohydrates showed very wide segregation for fructan (80 to 600 g kg⁻¹) and other NSC content, and were well-suited for detailed genetic and physiological analysis. Single marker analysis was carried out to study the association between the combined enzyme activity (CEA; acid invertase + 1-SST) and the Frc markers. Significant association between CEA and Frc markers has suggested genes regulating acid invertases or 1-SST or both underlie Frc. Leaf blade NSC did not correlate with bulb sugars and thus cannot be used as a phenotypic marker for early selection of bulb NSC traits.

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  • An investigation into ambulatory blood pressure measurement

    Hai, Lan (2012-05-23)

    Doctoral thesis
    Auckland University of Technology

    Hypertension is one of the most common cardiovascular diseases threatening people's health worldwide. Although, hypertension itself is rarely an acute problem, it increases the risk of cardiovascular events and kidney diseases. Recent studies have shown that the end-organ damage associated with hypertension is more strongly correlated with ambulatory blood pressure monitoring (ABPM) than with traditional clinic BP measurements. Currently, the ambulatory, cuff-based devices are predominantly based on automatic techniques which are inherently motion-sensitive. The other devices which claim to compensate for motion artefacts measure the arterial pressure at the wrist and are less accurate than cuff-based measurement. This research aims to develop a cuff-based ABPM technique which can measure BP accurately during their daily lives. The primary objective of this research is to investigate two major issues related to ABPM technique: (1) the theory of oscillometric BP measurement method used in most of ABPM device; (2) the method to compensate for the noises during the measurement. This thesis introduces for the first time a 3D finite element (FE) model which simulates the entire oscillometric BP measurement process. The model is validated by both arm simulator and clinical results. The brachial artery closure process and the factors of arm material properties in BP measurement are discussed. The model indicates that the nonlinearity of brachial artery plays the key role in oscillometric BP measurement. It also offers a new explanation of the common phenomenon: overestimation in the elderly and underestimation in the younger. Since BP pulse, arm motion and environmental tremors all lead to the upper arm skin stretches, it is anticipated that the strain distribution due to these causes is unique for different arm motion. This thesis also describes the design of a piezoelectric strain sensor array and the relevant method for eliminating the noises and determining the subject’s BP. A FE model, whose geometry is obtained from Visible Human Body dataset, is established to study surface strain distribution during different arm motions. Referring to its results, the piezoelectric sensor array is designed and used in the clinical experiments. Using the obtained signals, a generalized input-output configuration of the designed measurement system is developed. The transfer functions of the system are determined through empirical equations. Using the developed method, the device is able to detect the arm motions, compensate for the noises and determine patients’ BP. The results can be used as a guide for developing a new type of ABPM device insensitive to artefacts.

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  • The Post-LGM Evolution of Milford Sound, Fiordland, New Zealand: Timing of Ice Retreat, the Role of Mass Wasting & Implications for Hazards

    Dykstra, Jesse Leif (2012)

    Doctoral thesis
    University of Canterbury Library

    The plate-boundary Alpine Fault runs immediately offshore of the popular tourist destination of Milford Sound, which is visited by more than half a million tourists each year. Glaciers retreated from the fiord between ~24-16 ka, leaving behind a legacy of extreme topography, including some of the world's highest sea cliffs, which tower nearly 2 km above the fiord. Visitors come to view the spectacularly steep and rugged landscape, with many cruising the fiord by boat. This project utilizes surface exposure dating (TCND) of glacially modified surfaces, to gain further insight into the glacier retreat history of Milford Sound. Exposure dates from strategic locations near the entrance to the fiord indicate that the main trunk glacier had retreated about 9 km from its peak LGM position by ~18 ka. Additional TCND and calibrated Schmidt Hammer data from a range of positions within the Milford catchment provide strong evidence that the main trunk glacier receded rapidly after about 18 ka, retreating a further 16 km to a position near the present-day confluence of the Tutoko and Cleddau rivers, by ~16 ka. Available seismic reflection data suggest that post-glacial sediment infill has been strongly influenced by massive deposits of rock avalanche debris. New high-resolution bathymetric and seismic reflection data reveals the presence of at least 18 very large post-glacial rock avalanche deposits which blanket ~40% of the fiord bottom. Geomorphic mapping and field investigation reveal the presence of at least ten additional very large to giant terrestrial landslide deposits in the lower Milford catchment; radiocarbon and surface exposure dating indicate that these events occurred during the Holocene, between ~9-1 ka. Ages of six of these deposits are in agreement with published rupture dates on the southern on-shore portion of the Alpine Fault.

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  • Hidden Terminal Detection in Wide-Area 802.11 Wireless Networks

    Raynel, Scott McKenzie (2012)

    Doctoral thesis
    University of Waikato

    The hidden terminal problem is an important issue in wireless networks based on the CSMA medium access control scheme. Hidden terminals pose a complex challenge to network operators trying to identify the underlying cause of performance issues. This thesis describes new methods for the detection and measurement of the hidden terminal problem in wireless networks based on commodity hardware and software platforms. These new methods allow network operators to identify areas of a network where hidden terminals are likely to exist; detect instances of the hidden terminal problem occurring; and estimate the total impact hidden terminals are having on the performance of the network. A new framework for measurement of wireless networks is described which provides a new approach to wireless measurement on Linux based wireless routers. The new framework is used to implement the methods and they are deployed across an operational commercial wireless network and are shown to be useful.

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  • Mathematical Modelling of Cancer Cell Population Dynamics

    Daukšte, Liene (2012)

    Doctoral thesis
    University of Canterbury Library

    Mathematical models, that depict the dynamics of a cancer cell population growing out of the human body (in vitro) in unconstrained microenvironment conditions, are considered in this thesis. Cancer cells in vitro grow and divide much faster than cancer cells in the human body, therefore, the effects of various cancer treatments applied to them can be identified much faster. These cell populations, when not exposed to any cancer treatment, exhibit exponential growth that we refer to as the balanced exponential growth (BEG) state. This observation has led to several effective methods of estimating parameters that thereafter are not required to be determined experimentally. We present derivation of the age-structured model and its theoretical analysis of the existence of the solution. Furthermore, we have obtained the condition for BEG existence using the Perron- Frobenius theorem. Amathematical description of the cell-cycle control is shown for one-compartment and two-compartment populations, where a compartment refers to a cell population consisting of cells that exhibit similar kinetic properties. We have incorporated into our mathematical model the required growing/aging times in each phase of the cell cycle for the biological viability. Moreover, we have derived analytical formulae for vital parameters in cancer research, such as population doubling time, the average cell-cycle age, and the average removal age from all phases, which we argue is the average cell-cycle time of the population. An estimate of the average cell-cycle time is of a particular interest for biologists and clinicians, and for patient survival prognoses as it is considered that short cell-cycle times correlate with poor survival prognoses for patients. Applications of our mathematical model to experimental data have been shown. First, we have derived algebraic expressions to determine the population doubling time from single experimental observation as an alternative to empirically constructed growth curve. This result is applicable to various types of cancer cell lines. One option to extend this model would be to derive the cellcycle time from a single experimental measurement. Second, we have applied our mathematical model to interpret and derive dynamic-depicting parameters of five melanoma cell lines exposed to radiotherapy. The mathematical result suggests there are shortcomings in the experimental methods and provides an insight into the cancer cell population dynamics during post radiotherapy. Finally, a mathematical model depicting a theoretical cancer cell population that comprises two sub-populations with different kinetic properties is presented to describe the transition of a primary culture to a cell line cell population.

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  • Water Performance Benchmarks for New Zealand: Understanding Water Consumption in Commercial Office Buildings

    Bint, Lee Ellen (2012)

    Doctoral thesis
    Victoria University of Wellington

    There is an increasing amount of literature outlining the issues underlying water shortages and restrictions to come in most regions of New Zealand. The problem is not helped by rising demands and climatic changes, as well as both a lack of measured data, and a lack of any demand-side incentives. No attempt has been made to assess how the users of commercial buildings are consuming potable water. There are no benchmarks for water performance in buildings, hindering attempts to improve water efficiency. This study investigated the water use in 93 Auckland and Wellington commercial office buildings. The data collected from both survey level water audits (on-site investigations, historic billing analysis) and full water audits (water monitoring), were used to develop market-based water performance benchmarks, and a Water Efficiency Rating Tool (WERT). This was done to understand water consumption in these buildings, and to determine the feasibility of using performance based data for the development of a water benchmarking system. The principal results were in the form of both a benchmarking index system, and the WERT. The benchmarking study found that Net Lettable Area (NLA) was the most statistically and pragmatically appropriate driver for water use. lt also found that, due to the distinct difference in tariff structures and incentives between Auckland and Wellington, different benchmarks for the two regions (Auckland 'Typical' use 0.76m³ / m² / year, and Wellington 'Typical' use 1.03m³ / m² / year) were required. The WERT calculates a building Water Use Index (WUI- m³ / m² / year) , estimates its end-use disaggregation, and provides recommendations through outlining the financial viability of implementing specific water efficiency measures. This tool utilised six design criteria to ensure target market usability: accuracy (demonstrated at ±8. 5%) ; relevance and realism; practicality; promotion of understanding and action; objectivity; and effective communication. Further recommendations included satisfying some of the many knowledge gaps present in the New Zealand water industry concerning office building water use. These included: introducing a national legislative or standard document providing guidelines on demand-side management of water; investigation into changing tariff structures to include a volumetric charge for all building types to increase individual awareness and education of water use; research into the durability of water meters; and expanding the research to include other New Zealand regions.

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  • Inter-regionalism of nation-states: Asia-Europe Meeting (ASEM) as a case-study

    LAI, Suetyi (2012)

    Doctoral thesis
    University of Canterbury Library

    Writing a thesis is like writing a story book, this book is a story of the 17-year-old Asia-Europe Meeting (ASEM). It serves as a case-study of inter-regionalism, one of the newest cooperative mechanism in today’s international arena. Among a variety of cooperative frameworks, namely, multilateral global governance, effective multilateralism, regionalism, regionalisation, inter-regionalism is much less explored. This research determines how the rise of inter-regionalism influences the actors in the international arena and vice-versa. The key actors in inter-regionalism and their interaction are explored. Existing studies in the field of inter-regionalism in general and on the ASEM process in particular have been theory-led. There is a significant deficit of empirically-driven research in the field. In order to comprehensively understand inter-regionalism and the ASEM process, this research incorporates a substantial empirical focus. An unprecedented array of primary data is used. A variety of quantitative and qualitative data collection and analysis methods are employed to generate this unique and comprehensive empirical analysis of ASEM. Ultimately, this thesis demonstrates the persistent state-centrism and lack of actorness of regions and regional organisations as independent actors in the ASEM process. Nation-state remains the primary actor in inter-regionalism; yet, they turn to bilateralism when more concrete cooperation or affairs have to be handled. The proliferation of sideline meetings, although as by-product, becomes one of ASEM’s key added-value to international relations. The empirical analysis also finds that inter-regional fora like ASEM offer participants regular information and views updates and promote socialisation among government officials in the official track and among the involved individual from civil society in the unofficial track.

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  • Decoloured Bloodmeal Based Bioplastic

    Low, Aaron (2012)

    Doctoral thesis
    University of Waikato

    Renewable and compostable bioplastics can be produced from biopolymers such as proteins. Animal blood is a by-product from meat processing and is rich in protein. It is dried into low value bloodmeal and is used as animal feed or fertiliser. Previous work has shown that bloodmeal can be converted into a thermoplastic using water, urea, sodium dodecyl sulphate (SDS), sodium sulphite and triethylene glycol (TEG). This material is currently being commercialised as Novatein Thermoplastic Protein (NTP) and studies are working on improving its properties through production of composites and blends. In addition further studies are working on understanding its molecular structure before and after thermoplastic processing by utilising various analytical techniques. A specific area identified for improvement is its colour and smell. NTP is black in colour and has an offensive odour which means its current potential applications are limited to agriculture and waste disposal. Approximately 30 to 40% of plastics are used in short life span applications such as packaging and using bioplastics in these applications would be advantageous because of their compostability. To increase NTP’s possible range of applications to common applications such as packaging and increase its acceptance from consumers, its colour and odour must be removed without compromising its mechanical properties. Oxidative treatment methods for removing colour and odour from red blood cell concentrate (RBCC), modified red blood cell concentrate (mRBCC) and bloodmeal were investigated using hydrogen peroxide, peracetic acid (PAA), sodium hypochlorite, sodium chlorite, sodium chlorate and chlorine dioxide. Treatment effect on protein molecular weight, crystallinity, thermal stability, solubility, product colour and smell were investigated. Treating RBCC and mRBCC required multiple processing steps, had high water contents (67% and 93% respectively), foamed during treatment with peroxides and the protein was prone to hydrolysis. Bloodmeal contained 95% solids and was less sensitive to hydrolysis. The best decolouring and deodorising results were obtained by treating bloodmeal with 5% PAA. Using this novel treatment method, decolouring was completed within five minutes and produced a powder which was 67% white based on the RGB colour scale. Protein molecular weight was unaffected by PAA concentration, with a number average molecular weight ranging between 190-223 kDa for 1-5% PAA treated bloodmeal. However, its crystallinity decreased from 35% to 31-27% when treated with 1-5% PAA. Treating bloodmeal with 1-5% PAA also reduced the protein’s thermal stability, glass transition temperature (225°C down to 50°C) and increased its solubility from 11% to 85% in 1% SDS solution at 100°C. 3-5% PAA treated bloodmeal powder was extruded using different combinations of water, TEG, glycerol, SDS, sodium sulphite, urea, borax, salt and sodium silicate at concentrations up to 60 parts per hundred parts bloodmeal (pphBM). Partially consolidated extrudates and fully consolidated injection moulded samples were obtained using a combination of water, TEG and SDS. 4% PAA treated bloodmeal produced the best extruded and injection moulded samples and was chosen for investigating the effects of water, TEG and SDS concentration on consolidation and specific mechanical energy input (SME) as well as product colour and mechanical properties. Analysis of variance (ANOVA) showed SDS was the most important factor influencing ability to be extruded because it detangled protein chains and allowed them to form new stabilising interactions required for consolidation. The best extruded sample, which was 98% consolidated and 49% white, contained 40 pphBM water, 10 pphBM TEG and 6 pphBM SDS. TEG had the greatest effect on the product’s mechanical properties and colour after injection moulding because of its plasticisation effect. ANOVA showed TEG contributed 30.5% to changes in Young’s modulus, 66.9% to strain, 39.7% to toughness, 0.1% to UTS and 38.1% to colour. However, SDS also contributed 8.1% to changes in Young’s modulus, 13.7% to strain, 15.2% to toughness, 12.5% to UTS, 0.5% to colour. Initial water content contributed 19.7% to Young’s modulus, 1.0% to strain, 0.6% to toughness, 30.0% to UTS and 29.9% to colour. The best injection moulded sample was produced using 50 pphBM water, 20 pphBM TEG and 3 pphBM SDS. This produced a material which was 39% white, which had an almost transparent yellow/orange colour with a tensile strength of 4.62 MPa, Young’s modulus 85.48 MPa, toughness 1.75 MPa and 82.62% strain. The mechanical properties of the product manufactured in this study were comparable to those of NTP, but the product was mostly decoloured, allowing it to be easily pigmented and without an offensive odour.

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  • A Cascade Analysis for the IceCube Neutrino Telescope

    Hickford, Stephanie Virginia (2012)

    Doctoral thesis
    University of Canterbury Library

    IceCube is the largest operating neutrino observatory. An array of photomultiplier tubes deployed throughout a cubic kilometre of the Antarctic ice at the South Pole detect the Cherenkov radiation from neutrino-nucleon interactions. IceCube is capable of detecting neutrinos over a large energy range. The physics manifesto includes dark matter searches, cosmic ray observation, all sky point source searches, and particle physics parameter constraints. Astrophysical neutrinos are expected to originate from hadronic interactions in some of the most energetic regions in the Universe. The detection of high energy astrophysical neutrinos will provide direct information about the astrophysical sources that produced them. This thesis concentrates on the cascade channel for neutrino detection. Two separate studies are performed; a high energy cascade analysis and a parameterisation of the production of muons within hadronic cascades. The experimental data for the cascade analysis was taken by IceCube from April 2008 to May 2009 when the first 40 IceCube strings were deployed and operational. The analysis was designed to isolate the astrophysical neutrino signal from the atmospheric and muon background. Fourteen cascade-like events were observed, on a background of 2.2 ⁺⁰·⁶ ₋₀·₈ atmospheric neutrino events and 7.7 ± 1.0 atmospheric muon events. This gives a 90% confidence level upper limit of ΦlimE²≤ 7.46 × 10⁻⁸ GeVsr⁻¹s⁻¹cm⁻² , assuming an E⁻² spectrum and a neutrino flavour ratio of 1 : 1 : 1, for the energy range 25.12 TeV to 5011.87 TeV. Decay of hadronic particles in cascades produces muons. If the muons are energetic enough they can significantly alter the topology of the cascade and hence the reconstruction of the event in an analysis. The production of high energy muons within hadronic cascades was simulated and parameterised using Pythia and GEANT simulation programs.

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  • Microseismicity in the central Southern Alps, Westland, New Zealand

    Boese, Carolin (2012)

    Doctoral thesis
    Victoria University of Wellington

    Present-day seismicity associated with the central Alpine Fault and the zone of active deformation and rock uplift in the central Southern Alps is reported in this thesis. Robust hypocentre locations and magnitude estimates for ~2300 earthquakes have been obtained analysing 18 months of data from the Southern Alps Microearthquake Borehole Array (SAMBA), designed for this study. The earthquakes are distributed between the Alpine Fault and the Main Divide Fault zone and confined to shallow depths (90% of events ≤12.2 km). The thickness of the seismogenic zone follows lateral variations in crustal resistivity: earthquake hypocentres are restricted to depths where resistivities exceed 390 Ω m. Rocks at greater depth are interpreted to be too hot, too fluid-saturated, or too weak to produce detectable earthquakes. A low-seismicity zone extends between the Whataroa and Wanganui rivers at distances 15–30 km southeast of the fault, which is concluded to be a relatively strong, unfractured block that diverts deformation around it. A new magnitude scale is developed incorporating the effects of frequency-dependent attenuation, which enables magnitudes to be calculated consistently for earthquakes of different sizes and frequency contents. Focal mechanism solutions for 379 earthquakes exhibit predominantly strike-slip mechanisms. Inversion of these focal mechanisms to determine the prevailing tectonic stress field reveals a maximum horizontal compressive stress direction of 115±10°, consistent with findings from elsewhere in South Island. The 60° angle between the strike of the Alpine Fault and the direction of maximum horizontal compressive stress suggests that the Alpine Fault is poorly oriented in an Andersonian sense. Earthquake swarms of at least 10 events with similar waveforms frequently occur within the region, of which some were remotely triggered by two major South Island earthquakes. Focal mechanisms of the largest event in each swarm (ML≤2.8) reveal at least one steeply-dipping nodal plane (≥50°) and one well-oriented nodal plane in the tectonic stress field. The swarms exhibit a distinctly different inter-event time versus duration pattern from that of typical mainshock-aftershock sequences. The triggered seismicity commences with the passage of the surface waves, continues for ~5 and ~2 days, and is followed by a quiescence period of approximately equal length. Remotely triggered swarms occur delayed by several hours and their delay and locations are consistent with fluid diffusion from a shallow fluid reservoir. Estimated peak dynamic stresses (≥0.09 MPa) imposed by the surface waves are comparable to observations of triggering thresholds (>0.01 MPa) elsewhere. The triggered swarms have no apparent differences from the background swarms, and appear to have been clock-advanced. Tectonic tremor in the vicinity of the Alpine Fault coincides with a low-velocity, high-attenuation zone at depth. The tremor occurs at the downdip extension of the Alpine Fault and in the region where bending of the Australian and Pacific plates is largest at depths spanning 12–49 km. Similarities with tremor occurring on the San Andreas Fault near Cholame in terms of tremor duration, depth, spatial extent and amplitude distribution, imply property variations in the lower crust and upper mantle along the strike of the Alpine Fault.

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  • Mathematical Modelling of Cancer Cell Population Dynamics

    Daukste, Liene (2012)

    Doctoral thesis
    University of Canterbury Library

    Mathematical models, that depict the dynamics of a cancer cell population growing out of the human body (in vitro) in unconstrained microenvironment conditions, are considered in this thesis. Cancer cells in vitro grow and divide much faster than cancer cells in the human body, therefore, the effects of various cancer treatments applied to them can be identified much faster. These cell populations, when not exposed to any cancer treatment, exhibit exponential growth that we refer to as the balanced exponential growth (BEG) state. This observation has led to several effective methods of estimating parameters that thereafter are not required to be determined experimentally. We present derivation of the age-structured model and its theoretical analysis of the existence of the solution. Furthermore, we have obtained the condition for BEG existence using the Perron-Frobenius theorem. A mathematical description of the cell-cycle control is shown for one-compartment and two-compartment populations, where a compartment refers to a cell population consisting of cells that exhibit similar kinetic properties. We have incorporated into our mathematical model the required growing/aging times in each phase of the cell cycle for the biological viability. Moreover, we have derived analytical formulae for vital parameters in cancer research, such as population doubling time, the average cell-cycle age, and the average removal age from all phases, which we argue is the average cell-cycle time of the population. An estimate of the average cell-cycle time is of a particular interest for biologists and clinicians, and for patient survival prognoses as it is considered that short cell-cycle times correlate with poor survival prognoses for patients. Applications of our mathematical model to experimental data have been shown. First, we have derived algebraic expressions to determine the population doubling time from single experimental observation as an alternative to empirically constructed growth curve. This result is applicable to various types of cancer cell lines. One option to extend this model would be to derive the cell cycle time from a single experimental measurement. Second, we have applied our mathematical model to interpret and derive dynamic-depicting parameters of five melanoma cell lines exposed to radiotherapy. The mathematical result suggests there are shortcomings in the experimental methods and provides an insight into the cancer cell population dynamics during post radiotherapy. Finally, a mathematical model depicting a theoretical cancer cell population that comprises two sub-populations with different kinetic properties is presented to describe the transition of a primary culture to a cell line cell population.

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  • IR Studies of the Zirconia-Water Interface

    Scholz, Jan (2012)

    Doctoral thesis
    University of Otago

    The aim of the present work was to contribute to an understanding of the reactivity of hydroxylated zirconia surfaces towards hydration and anion adsorption. IR spectroscopy was used to characterise the structure and bonding of surface functional groups and interfacial water molecules, to study slow surface reconstruction processes and to obtain insights into the specific adsorption of chloride, sulphate, phosphate and tungstate ions. To account for the structural diversity of the zirconia-water interface and hence its spectral complexity, both zirconia nanoparticle films and structurally related materials including crystalline zirconyl chloride n-hydrates, zirconia hydro gels and aqueous zirconia sols were studied spectroscopically. Thermal and isothermal dehydration and humidity-controlled hydration studies of zirconyl chloride octahydrate, zirconia hydro gels and zirconia nanoparticle films as well as anion adsorption studies to zirconia nanoparticle films from aqueous solutions under static conditions were conducted. Further, X-ray single crystal, thermogravimetric, mass spectrometric and calorimetric data as well as electrophoretic mobility measurements were used to infer additional structural information. Vibrational data for hydroxylated zirconia polymorphs, crystalline hydrogen chloride n-hydrates and size-selected water clusters was employed for spectral assignments. The characteristic vibrational signature of stoichiometric zirconyl chloride n-hydrates was obtained and assignments for vibrational modes of discrete Cl-•••H+-O, Cl-H•••O, O•••H+•••O, O-H•••O and Zr-(OH2)3 groups are given. H2O52+- and H3O2--like entities were evident in zirconyl chloride octa and -hexahydrate. A hydrolysis mechanism for the reaction of H2O(g) and HCl(aq) with Zr4+ sites in Zr-O-Zr groups is proposed (chemisorption). The formation of a strongly H-bonded network of surface-bound water molecules at the zirconia surface was observed (physisorption), and the role of continuous yet slow Zr-O-Zr bond cleavage in the formation of a gel-like surface layer is highlighted. The loss in crystallinity of the zirconia surface led to a gradual increase in the positive net surface charge of zirconia particles. The latter seems to be accountable for the embedding of chloride ions into the network of surface-bound water molecules; and a specific chloride adsorption mechanism is suggested. Sulphate, phosphate and tungstate adsorption studies to zirconia nanoparticle films revealed binding motifs of the oxoanions at pH 3 and 1; and their adsorption affinities were compared in view of considerable differences in Langmuir equilibrium constants, Kads.

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  • Synthesis and study of Quaternary Nitrogen Surfactants

    Jordan, Deborah Kay (2012)

    Doctoral thesis
    University of Otago

    The effect of head group modification on the solubility and antimicrobial potency of some quaternary nitrogen surfactants (QNSs) was investigated. Using high yielding Menshutkin reactions, a homologous series of monomeric, dimeric and polymeric QNSs based on aliphatic ammonium and aromatic pyridinium head groups were synthesised. The hydrophilicity of the head groups was increased via hydroxymethyl addition and decreased using ethyl substitution. The tails used were saturated, straight alkyl chains ranging from 6 to 22 carbons in length. The hydrophobicity of the QNSs was established by calculating their predicted partition coefficient in an octanol/water mix (Log P) and by measuring their critical micelle concentration (cmc). As anticipated, the QNSs with longer alkyl tails were more hydrophobic with lower cmc and increased Log P values. Alterations to the head groups showed predictable results for all head groups except the hydroxymethyl addition on the pyridinium head group. The Log P value predicted an increased hydrophilicity, while the cmc suggested an increased hydrophobicity. This difference (lower cmc) was postulated to be due to decreased repulsion of the head groups allowing for micellisation at lower concentrations. This theory was supported by crystal structure analysis which showed that the hydroxymethyl addition caused the QNSs to pack more closely. Measurement of limiting molar conductivity (Λo) also showed that the hydroxymethylpyrdinium compounds were unexpectedly less solvated than the unsubstituted counterparts, and the micelle size was increased by the presence of the hydroxymethyl group. This data as a whole suggested the hydroxymethyl group was not solely acting to decrease the hydrophobicity. The antimicrobial activity of each QNS was assessed against three Gram positive bacteria (Staphylococcus aureus, Listeria innocua, Bacillus subtilis); three Gram negative bacteria (Pseudomonas aeruginosa, Yersinia enterocolitica, Escherichia coli); a fungus (Aspergillus niger); and a yeast (Saccharomyces cerevisiae), using a minimum inhibitory concentration (MIC) assay. The longer chain compounds were generally found to be more effective against the bacteria with a cut-off seen in many cases at the hexadecyl derivative. The charge of the bacteria cell surface (ζ-potential) became increasingly positive at higher concentrations of QNS and transmission electron microscopy (TEM) showed that at concentrations above the MIC the cytoplasmic membrane had been compromised. These studies suggested the primary mode of action of the QNS against the bacteria was due to the attraction of the QNS to the cytoplasmic membrane of the bacterial cell which resulted in its destabilisation. Destabilisation of the bacterial cytoplasmic membrane occurred at lower concentration for QNSs with longer alkyl tails. It was therefore postulated that the hydrophobicity of a QNS could be used to predict its antimicrobial potency. However, when the MIC was related to Log P using a quantitative structure activity relationship (QSAR) it was demonstrated that the relationship was not linear, and that while parabolic and bilinear models provided a better approximation to the observed data no model sufficiently accounted for all the data. The research presented in this thesis has shown that the physical properties and antimicrobial activity of QNSs varies greatly with altered head group hydrophobicity. It has been demonstrated that very small changes to the head group can lead to unexpected physical properties which changes their interactions with micro-organisms. The antimicrobial action of these compounds has been shown to rely on the attraction of the cationic head group to the cytoplasmic membrane which is then destabilised by the alkyl tail. Findings from this project will help in the development of more potent QNSs and a greater understanding of the interaction of QNSs with cytoplasmic membrane.

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  • Design and Implementation of an Efficient and Scalable Software Distributed Shared Memory System

    Yu, Byung-Hyun (2012)

    Doctoral thesis
    University of Otago

    This thesis presents the design and implementation of our novel hybrid software DSM system. We call our system hybrid home-based EAC (HHEAC) since the system implements our novel exclusive access consistency model (EAC) based on the hybrid protocol of the homeless and home-based protocols. HHEAC guarantees only that shared variables inside a critical section are up to date before the accesses. Other shared variables outside a critical section are guaranteed to be up to date after the next barrier synchronisation. Our home-based DSM implementation is different from the previous implementations in that a home node does not receive any diffs from non-home nodes until the next barrier synchronisation. It is also different in that during a lock synchronisation required diffs are prefetched before the critical section, which reduces not only data traffic but also page faults inside the critical section. We also present a diff integration technique that can further unnecessary data traffic during lock synchronisation. This technique is especially effective in reducing data traffic for migratory applications. Finally, we develop a home migration technique that solves the wrong home assignment problem in the home-based protocol. Our technique is different from others in that an optimum home node is decided before updating a home node. To evaluate our system, we performed various experiments with well-known benchmark applications, including a novel parallel neural network application.The performance evaluation shows that HHEAC is more scalable than other DSM systems such as TreadMarks and removes the home assignment problem in the conventional home-based protocol.

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  • "Let Us Go to Him": The Story of Faith and the Faithfulness of Jesus in Hebrews

    Easter, Matthew Charles (2012)

    Doctoral thesis
    University of Otago

    This thesis investigates faith and the faithfulness of Jesus in Hebrews. Preceding studies have understated the christological dimension of faith or have made Jesus the object of faith. Furthermore, while Käsemann emphasized the corporate motif of the travelling people of God for Hebrews, most interpreters still operate with a largely individualistic concept of faith. I argue that faith in Hebrews is manifested in four dimensions: christological, eschatological, ethical, and ecclesiological. That is, faith is exemplified and enabled by Jesus (christological dimension), who in faith endured suffering to death (ethical) in hopes of postmortem life (eschatological). Humans exercise this faith by persevering with the travelling people of God (ecclesiological). I read Hebrews with an eye to story, and the thesis is organized with these narrative concerns in view. Chapter 2 lays the exegetical and philosophical foundations for such an approach to Hebrews, arguing that Hebrews operates with stories and that human identity is itself a story. Our treatment of Hebrews deals with the two narrative identities the author presents, which are laid out succinctly in Heb 10:39: “but we are not (story 1) of timidity unto destruction, but (story 2) of faith unto the preservation of the soul.” I discuss these two stories in parts 2 and 3 of the thesis. Part 2 of the thesis (chapters 3-5) addresses “the default human story.” We find that the default human story is characterized by unfaithfulness and concludes assuredly in death. Although God intended glory, honor, and dominion for humanity (Heb 2:6-8), we do not at present see this divine intention fulfilled. Instead, humans are shackled by a guilty conscience and are inherently unfaithful. The assured conclusion of death holds true even for Israel’s heroes of faith, who did not receive the promise and are not made perfect (11:13, 39-40). Although these chapters do not address faith per se they are necessary pieces to fill out the whole vision of the understanding of faith in Hebrews. To understand “faith” fully, we need to understand “unfaith.” Part 3 of the thesis (chapters 6-8) discusses the story rewritten in Christ. This story, lived out perfectly by Jesus, is characterized by faith in the face of death and concludes assuredly in postmortem life. Hebrews depicts Jesus in martyrological terms, whose faith is associated with endurance through suffering in hope of postmortem reward. The conclusion to the story of faith is assured because the pioneer of faith is also the perfecter who successfully realized life after death. Part 4 of the thesis (chapter 9) addresses how human beings exercise faith. The question of how a person first participates in the story of faith is difficult, since the author of Hebrews never speaks to this question directly. However, looking at how the author expects humans to exercise faith after they are “in” may offer a glimpse into the way humans can “get in.” I argue Jesus’ faithfulness in sacrifice enables humans to exercise faith, and we subsequently follow the model of Jesus’ faith (christological dimension), moving forward in hope of postmortem life (eschatological). In the present, faith entails endurance to the end (ethical), and this endurance likely involves suffering. Ultimately, we find that the author of Hebrews expects humans to join together with others being faithful (ecclesiological dimension), “going to Jesus outside the camp, bearing his reproach” (13:13).

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  • Regime Transition and Foreign Policy: The Case of Russia's Approach to Central Asia (1991-2008)

    Hazelton, Glen (2012)

    Doctoral thesis
    University of Otago

    In 1991, Russian embarked on an ambitious regime transition to transform the country from communism to democracy. This would be a massive transformation, demanding economic, political, institutional, and social change. It was also expected that the transition would result in significant foreign policy adaptation, as Russia’s identity, direction and fundamental basis for policy-making was transformed. However, it was an unknown quantity how transition in the domestic environment would interact with foreign policy and what the nature of these changes would be. This thesis examines the relationship between regime transition and Russia’s foreign policy. It begins with an examination of literature on regime transition and the types of changes that potentially impact policy-making in a democratising state. It then moves to examining the policy environment and its impact on the contours of policy in each of the Yeltsin and Putin periods, drawing links between domestic changes and their expression in foreign policy. How these changes were expressed specifically is demonstrated through a case study of Russia’s approach to Central Asia through the Yeltsin and Putin periods. The thesis finds clearly that a domestic transitional politics was a determining factor in the nature, substance and style of Russia’s foreign relations. Under Yeltsin, sustained economic decline, contested visions of what Russia’s future should be and where its interests lay, as well as huge institutional flux, competition, an unstructured expansion of interests, conflict, and the inability to function effectively led to an environment of policy politicisation, inconsistency, and turmoil. Tracing relations with Central Asia through this period demonstrates the challenges of transitional foreign policy. Although an apparent ‘consensus’ on a focus on ‘near abroad’ partners emerged in the wake of rising nationalism and political conflict in 1993, it was never consistently implemented. Continued uncertainty, division, and unrestrained political competition, meant Moscow never substantiated opportunities to maintain or increase its influence in the region. This situation changed drastically under Vladimir Putin. Economic recovery, greater agreement on identity and national interests, transformation of the institutional environment and the installation of a more managed, delegative form of democracy stabilised the policy-making context. The political system became more personalised and tightly controlled, while political liberalism and pluralism declined. A smaller range of actors influenced foreign policy and their involvement was more predictable and constructive, though less autonomous. Policy shifted from the previously reactive nature where it catered more to immediate political interests, to demonstrating greater coherence, consistency and long-term, strategic focus. The subsequent change in Russia’s policy towards Central Asia was signficant. Putin saw Russia’s relations with Central Asia as part of an integrated approach to the world. He refocused relations to target economic and security considerations; areas of primary Russian interest and in which he knew Russia had something to offer. The greater coordination of a range of foreign policy actors and the growth of resources at the state’s disposal allowed for more comprehensive strategies. Importantly, it also laid the basis for a more significant future Russian presence, even in spite of the challenges presented by the more vigorous external activity in the region following September 11. Ultimately, Putin’s domestic changes meant that regime transition came to matter less in the formulation and implementation of foreign policy and allowed Russia to pursue a more successful foreign policy in Central Asia.

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  • Dietrich Bonhoeffer's Spatially Structured Ecclesiology. Reconfiguring the Confession of Christ's Presence.

    Fergus, Donald Murdoch (2012)

    Doctoral thesis
    University of Otago

    From the beginning of his career Dietrich Bonhoeffer was invested in describing and then crafting a form of religious community that provided a way of being human, and a form of corporate sociality that was grounded in and grew out of the presence of the person of Jesus Christ. The sanctorum communio was that form of sociality. Bonhoeffer’s ecclesiology was the outcome of his relentless searching for a form of the church that could meet the challenges of National Socialism’s Third Reich and contribute meaningfully to the life of the German nation. A reading of Bonhoeffer reveals the widespread use of spatial metaphors or descriptors in the development of his ecclesiology. Bonhoeffer was always interested in the empirical church and a careful reading shows how his spatially structured ecclesiology underlies and supports the church’s Christological core and its communal nature, giving a concrete form to the ministry of the church in the culture in which it is embedded. Bonhoeffer’s ecclesiology serves to shape the way in which the church structures its confession of Christ’s presence in the world, while at the same time keeping a steady eye on the church as a creation and gift of God. The quest for a vibrant articulation of Christ’s presence becomes a persistent hermeneutic throughout Bonhoeffer’s writing. His robust doctrine of the church based on the images of place and space leads eventually to the form of the suffering servant, Jesus Christ. Collectively, the images build a compelling case for a form of sociality that brings the motifs of self-giving love and of dying and rising in Christ together to shape discipleship in Christ and the theological reflection on that discipleship. Bonhoeffer's use of spatial imagery places the church’s central acts of announcing and bearing witness to the word of God, and its celebration of the sacramental enactments of that word of promise and hope within a particular space in which the church is highly visible. Bonhoeffer called this ‘the living space [Lebensraum] of the visible church-community’. It is from within this living-space that the church is committed to pushing back the boundaries of life until the world is held by Jesus Christ, the Lord of Life.

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