11,873 results for Doctoral

  • A multi-criteria approach to the evaluation of food safety interventions.

    Dunn, Alexander Hiram (2015)

    Doctoral thesis
    University of Canterbury Library

    New Zealand faces a range of food safety hazards. Microbial hazards alone were estimated to cause over 2,000 years of lost healthy life in 2011 (Cressey, 2012) and $62m in medical costs and lost productivity in 2009 (Gadiel & Abelson, 2010). Chemical hazards are thought to be well managed through existing controls (Vannoort & Thomson, 2009) whereas microbial hazards are considered harder to control, primarily due to their ability to reproduce along the food production chain. Microbial hazards are thought to cause the majority of acute foodborne gastroenteritis. This research reviewed food safety literature and official documentation, and conducted 55 interviews, mostly with food safety experts from different stakeholder groups, to examine the food safety decision-making environment in New Zealand. This research explores the concept of the ‘stakeholder’ in the context of food safety decision-making and proposes an inclusive ‘stakeholder’ definition as any group which is able to affect, or be affected by, the decision-making process. Utilising this definition, and guided by interviews, New Zealand stakeholders in food safety decision-making were identified and classified as follows: •Regulators •Public health authorities •Food safety scientists/academics •Consumers •Māori •Food Businesses (further classified as): o Farmers o Processors o Food retailers o Exporters Interviews with stakeholders from these groups highlighted twelve criteria as being relevant to multiple groups during food safety intervention evaluation: •Effectiveness •Financial cost •Market Access •Consumer Perceptions •Ease of Implementation •Quality or Suitability •Quality of Science •Equity of Costs •Equity of Benefits •Workplace Safety •Cultural Impact •Animal Welfare There are a number of different ways to measure or assess performance on these criteria. Some are able to be quantitatively measured, while others may require the use of value judgements. This thesis used the Disability-Adjusted Life Year (DALY) metric for quantifying effectiveness during the testing of different MCDA models. This thesis reviews the MCDA process and the food safety specific MCDA literature. There are different ways of conducting MCDA. In particular, there are a large number of models available for the aggregation phase; the process of converting model inputs, in the form of criteria scores and weights, into model recommendations. This thesis has described and reviewed the main classes of model. The literature review and interview process guided the construction and testing of three classes of MCDA model; the Weighted Sum, Analytic Hierarchy Process (AHP) and PROMETHEE models. These models were selected due to their having different characteristics and degrees of complexity, as well as their popularity in the food safety and Health Technology Assessment (HTA) literature. Models were tested on the problem of selecting the most appropriate intervention to address the historic Campylobacter in poultry problem in New Zealand during the mid-2000s. Experimentation was conducted on these models to explore how different configurations utilise data and produce model outputs. This experimentation included: •Varying the format of input data •Exploring the effects of including/excluding criteria •Methods for sensitivity analysis •Exploring how data inputs and outputs can be elicited and presented using visual tools • Creating and using hybrid MCDA models The results of this testing are a key output of this thesis and provide insight into how such models might be used in food safety decision-making. The conclusions reached throughout this research phase can be classified into one of two broad groups: •Those relating to MCDA as a holistic process/methodology for decision-making •Those relating to the specific models and mathematical procedures for generating numerical inputs and outputs This thesis demonstrates that food-safety decision-making is a true multi-criteria, multi-stakeholder problem. The different stakeholders in food-safety decision-making do not always agree on the value and importance of the attributes used to evaluate competing intervention schemes. MCDA is well suited to cope with such complexity as it provides a structured methodology for the systematic and explicit identification, recording and aggregation of qualitative and quantitative information, gathered from a number of different sources, with the output able to serve as a basis for decision-making. The MCDA models studied in this thesis range from models that are simple and quick to construct and use, to more time consuming models with sophisticated algorithms. The type of model used for MCDA, the way these models are configured and the way inputs are generated or elicited can have a significant impact on the results of an analysis. This thesis has identified a number of key methodological considerations for those looking to employ one of the many available MCDA models. These considerations include: •Whether a model can accommodate the type and format of input data •The desired degree of compensation between criteria (i.e. full, partial or no compensation) •Whether the goal of an analysis is the identification of a ‘best’ option(s), or the facilitation of discussion, and communication of data •The degree of transparency required from a model and whether an easily understood audit trail is desired/required •The desired output of a model (e.g. complete or partial ranking). This thesis has also identified a number of practical considerations when selecting which model to use in food safety decision-making. These include: •The amount of time and energy required of stakeholders in the generation of data inputs (elicitation burden) •The degree of training required for participants •How data inputs are to be elicited and aggregated in different group decision-making environments •The availability of MCDA software for assisting an analysis Considering the above points will assist users in selecting a suitable MCDA model that meets their requirements and constraints. This thesis provides original and practical knowledge to assist groups or individuals looking to employ MCDA in the context of food-safety intervention decision-making. This research could also serve as a guide for those looking to evaluate a different selection of MCDA models.

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  • Morphosyntactic development of typically- and atypically-developing Bangla-speaking children.

    Sultana, Asifa (2015)

    Doctoral thesis
    University of Canterbury Library

    Aims: Verb morphology, arguably, is identified as an area of exceptional challenge for the language development of both young typically-developing children, and children with language difficulties (Leonard, 2014a; Rice & Wexler, 2001). The developmental patterns of verb acquisition are found to be strongly governed by the typological properties of the ambient language; often language errors found in fusional languages (e.g. English and German) are significantly different from those found in agglutinative languages (e.g. Turkish and Tamil) (cf. Phillips, 2010). Therefore, the purpose of the study was to explore the developmental trends in the acquisition of verb morphology in Bangla, a language with agglutinative features. The first objective was to examine the morphosyntactic development of typically-developing (TD) Bangla-speaking children with regard to three verb forms, namely the Present Simple, the Present Progressive and the Past Progressive. A second objective was to examine the development of the three verb forms among a group of children with language impairment (LI). Rationale: Since Bangla is spoken by a large population, the acquisition data of Bangla represents a significant number of people, and the findings from the acquisition studies, when considered for intervention purposes, serve a considerably large population. Also, given that the normative data of language acquisition is unavailable for Bangla which leads to the absence of a language-specific assessment and intervention for LI children, the present study is expected to have importance for Bangla-speaking contexts. Method: Before the main study commenced, a pilot study was conducted with 19 Bangla-speaking TD children aged between two and four (years) in order to explore the developmental characteristics of the verb forms and to evaluate the research instruments identified for the actual study. The main study included 70 TD children between 1;11 and 4;3 years who were recruited from six daycare centres of Dhaka, Bangladesh. The children participated in three elicitation tasks, each to elicit one verb form, and a 20-minute play session that yielded a spontaneous language sample from each child. The researcher scored children’s performances on the three tasks, and transcribed the language samples using transcription software (Systematic Analysis of Language Transcripts). The elicitation tasks were used to determine children’s mastery of the forms, whereas the language samples were used to calculate a set of language measures associated with morphological development. The study also included a group of nine children with LI between 3;11 and 9;4 years who participated in the same set of tasks as the TD children. These children were recruited from a special school in Dhaka. Findings: The results revealed that, for both TD and LI children, the Present Simple form was acquired with highest accuracy which was followed by the scores in the Present Progressive and the Past Progressive forms respectively. The error patterns indicated a qualitative progress even in children’s errors, which was consistent with the accuracy rates of the target forms. Based on the TD children’s performance on the three tasks, a developmental sequence for the three Bangla verb forms was proposed. Results also identified that Mean length of Utterance (MLU) did not have stronger associations with the tasks scores than did Age. Among the determinants tested, Bound Morpheme Type (BMT) was identified to have the strongest associations with the task scores. Analyses of the data from the LI children revealed a significant difference between the TD and the LI children on all three tasks and the other language measures. When compared against the proposed developmental stages, the children within the LI group were found to different in terms of their morphosyntactic capacities. A sub-group of LI children also did not conform to any stages of typical development. Conclusions: Results of the present study offer directions for future investigations in a wide range of areas of Bangla morphosyntax that need to be examined with both TD and LI children. Moreover, factors associated with language development that the present study did not examine (e.g. the role of input) also need to be addressed in future studies. Above all, there is a strong need for ongoing investigations in order to identify a comprehensive picture of morphosyntactic development of Bangla-speaking TD children, which can then lead to the assessment of a range of language impairments in Bangla.

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  • A spatial analysis of dengue fever and an analysis of dengue control strategies in Jeddah City, Saudi Arabia

    Alkhaldy, Ibrahim (2014)

    Doctoral thesis
    University of Canterbury Library

    Dengue fever poses a constant serious risk and continues to be a major public health threat in Saudi Arabia, particularly in the city of Jeddah where, since 2006, despite formally introduced Control Strategies, there has been a significant increase in the number of cases. International literature suggests that a range of variables can influence the persistence of dengue, including climatic conditions, the quality of the urban environment, socioeconomic status and control strategies. The overall aims of this research are to understand neighbourhood influences on the pattern of dengue fever across Jeddah City and to make a preliminary determination of the enabling factors for, and barriers to, the effective implementation of the Control Strategies for dengue fever in Jeddah City. A mixed methods research design using quantitative and qualitative data was used. Quantitative data were obtained from administrative sources for dengue fever cases and some of the spatial and temporal variables associated with them, but new variables were created for neighbourhood status and the presence of surface water. Qualitative data are drawn from key informant interviews with 15 people who were, or who had been, working on dengue fever Control Strategies. A qualitative descriptive analysis was based on pre- determined and emergent themes. The spatial and temporal analysis of the variables related to dengue fever in Jeddah City neighbourhoods revealed that neighbourhood status has a direct relationship with dengue fever cases, which is mediated through population density and the presence of non- Saudi immigrants. While there was no relationship with the presence of swamps, seasonal variations in the incidence of dengue were most pronounced in neighbourhoods of low socioeconomic status. The qualitative review of dengue Control Strategies indicated five themes: (1) workforce characteristics and capability, (2) knowledge about dengue fever in Saudi Arabia and Jeddah City, (3) operational strategies for dengue fever control in Jeddah City, (4) the progress of implementation, and (5) overall view of the Government strategies in Jeddah City. This analysis found that the Strategies were well regarded but that aspects of implementation were not always effective. Nevertheless, both quantitative and qualitative results showed the persistence dengue fever problems in Jeddah City neighbourhoods and suggested how cases might be controlled. The number of dengue fever cases in Jeddah City neighbourhoods could continue to rise if the direct and indirect variables affecting dengue fever at the neighbourhood level are not well controlled. Careful attention to the further monitoring of patterns of dengue and specific neighbourhood Control Strategies are recommended, and established Control Strategies need to be implemented as designed. Nonetheless, there is still a need to develop new approaches that can examine and address neighbourhood level issues of dengue fever control.

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  • The Influence of Music Congruence and Message Complexity on the Response of Consumers to Advertisements

    Seneviratne, Buddhakoralalage Leelanga Dananjaya (2015)

    Doctoral thesis
    University of Canterbury Library

    The overall aim of this study was to examine how the characteristics of two salient stimuli -music and message- of an audio advertisement influence the psychological state of consumers and how such a state subsequently determines their cognitive and affective responses to the advertisement. In achieving this aim, this study was guided by a combination of two cognitive resource utilisation theories, Limited Capacity Model of Motivated Mediated Message Processing (Lang, 2000) and Resource-Matching Hypothesis (Anand & Sternthal, 1989). In particular building upon inconsistency and load theories, this study proposed that certain stimulus characteristics prompted certain states of a consumer’s cognition. These two stimulus characteristics were the congruence of musical stimulus and the complexity of the message stimulus. The model then predicted the potential effect of these characteristics on certain psychological states (Psychological Discomfort and Cognitive Load) leading to affective (Attitude towards Advertisement) and cognitive (encoding, storage, and retention) responses. To empirically examine this model, an online experiment (using a 2 x 2 between-subject x 2 with-in subject mix design) was conducted, in which a mixed sample of 284 subjects was exposed to a set of audio advertisements especially designed for this study. Unfamiliar music in conjunction with a fictitious brand was used and the exposure level was maintained at low. ANCOVA, MANCOVA, two-stage hierarchical regression analysis, and Repeated-measures MANCOVA were administered to test the hypotheses presented in the conceptual model. Among major findings were that the multiple informational structures in a complex message positively influenced cognitive load, while congruent music was capable of attenuating the level of cognitive load. Incongruent music, on the other hand, was capable of generating a dissonance state experienced as psychological discomfort that in turn increased the level of cognitive load as a result of listener’s trying to resolve such a state. Both dissonance and cognitive load negatively influenced attitude towards advertisements, and the affect primacy of attitude formation appeared to be more applicable. Though high cognitive load clearly undermines encoding, storage, and retrieval processes, no evidence was found to support the Resource-matching Hypothesis. Furthermore, the findings suggested that the cognitive load offset by the congruent music would increase advertisement effectiveness by enabling its message to carry more information and by generating more favourable attitudes.

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  • Hydrodynamics and chemistry of silica scale formation in hydrogeothermal systems.

    Kokhanenko, Pavlo (2015)

    Doctoral thesis
    University of Canterbury Library

    The extraction of geothermal heat can cause precipitation of the minerals dissolved in geothermal fluid. Their deposition on the walls of wells and above-ground plant and in pores near reinjection wells, also known as mineral scaling, is one of the main obstacles to increasing the effectiveness of utilization of the limited geothermal resources. If not controlled properly it can result in accumulation of a significant amount of scale which obstructs pipes and reinjection wells and reduces the efficacy of heat exchangers. The most abundant mineral in geothermal fluid is silica and thus its precipitation can cause the highest scaling rate. While this dissertation is devoted to the study of silica scaling the results obtained may be applicable to other minerals with similar deposition mechanism. Oversaturated silica is known to precipitate from aqueous solution either by the direct chemisorption of single silicic acid molecules (monomers) or by forming colloidal particles suspended in the solution. These particles can subsequently be transported to, and attach onto, a wall. This process of colloidal silica deposition was previously recognised to cause much faster scaling than the direct deposition of silica monomers under typical geothermal plant conditions. While the chemical kinetics of silica polymerization and colloid formation are relatively well understood, transport of these colloids and their stability, which control their aggregation and attachment rates, on the other hand are not. Previous studies of the silica scaling process have identified prominent effects of geothermal brine hydrodynamics on the scaling rate. It was found to increase with the flow rate and particle size, thus suggesting the dominance of the advective (inertial) deposition of colloidal silica. However, this conclusion contradicted the present theory of particle transport in turbulent flows which argues the dominance of the diffusive transport for the relevant range of particle sizes (<1 μm). The development and continuing improvement of the anti-scaling measures required deeper understanding of the complex combination of the phenomena involved in the process of silica scaling. This was pursued in the present study using theoretical and experimental methods. First, the rate of colloidal silica transport from a turbulent flow onto the internal surface of a circular pipe, a cylinder and a flat plate were calculated using available analytical and numerical methods. The obtained theoretical transport rate was found to be about four orders of magnitude higher than the corresponding experimental scaling rate. The latter was determined in the previous studies to be 4.2·10-8 kg/s/m2 for silica colloids of 125 nm in diameter which corresponded to the dimensionless deposition velocity (the dimensionless deposition velocity is the scaling rate normalised by the particle mass concentration and friction velocity) of 1.2·10-6 for the dimensionless particle relaxation time of 2·10-4. Next, based on the standard DLVO theory of particle interactions and in the framework of the Smoluchowski approach the probability of colloidal silica particle attachment to a wall was found to be 10-6. Therefore, the theoretical scaling rate, calculated as a product of this probability and the above-mentioned transport rate was two orders of magnitude lower than the experimental scaling rate. This suggested that the implemented theoretical approach either underestimated particle transport rate or overestimated particle stability. Both possibilities are explored in this dissertation. In addition, the silica scaling rate was measured for a range of conditions: particle size from 20 to 60 nm, particle concentration 1600-10000 ppm, friction velocity from 0.09 to 0.18 m/s (Re = 9-50·103) and ionic strength from 30 to 80 mM, pH 8.1-9.5 and temperature from 25 to 44 °C. For this, laboratory experiments were designed and progressively modified in order to improve the repeatability of the results and to study the scaling process. In these experiments colloidal silica deposition onto the walls of mild steel pipe sections was studied with a recirculating flow rig with variable (but controllable) particle size, concentration, flow rate, pH and ionic strength of the solution. In addition, a parallel plate flow test section was designed and built which will provide better capabilities for the control over the hydrodynamic and test surface conditions in future experiments. The control over the chemical conditions was achieved by the use of the synthetic colloidal solutions. Two methods of their production – hydrolysis of either sodium metasilicate or active silicic acid – were employed. The influence of the synthesis conditions, ion content and pH on the long term behaviour of these colloidal solutions was investigated. The particle size data, obtained using dynamic light scattering (DLS) and verified by electron microscopy, was analysed and compared against the predictions of the current models of nanoparticle growth and stability. The kinetic aggregation was identified to be the dominant particle growth mechanism. Experimental data collected during the long-term observations of the particle growth allowed relationships between the aggregative stability and such parameters as the particle size, ion concentration and pH of the solution to be elucidated. In particular, the aggregative stability of 10-20 nm particles was found to be 108-1010 which is 7-9 orders of magnitude higher than the corresponding DLVO stability. It was also found to decrease with the increase of the particle size. This agreed with the theory of the colloid stabilization by steric interactions. Moreover, the model of the “gel” layer was used to explain the observed “anomalies” of the colloidal silica behaviour. The deposition experiments conducted with these synthetic colloidal solutions showed that the scaling rate increased with the particle size, flow rate and ionic strength (IS) of the solution. Thus, it was measured to be 9.7·10-9 kg/s/m2 for the 45 nm particles in a solution with IS = 0.05 M, which corresponded to the dimensionless deposition velocity of 6.6·10-8 for a dimensionless particle relaxation time of 2.2·10-6. The scaling rate was calculated for these conditions by multiplying the corresponding transport rate and the actual attachment probability determined as an inverse of the experimental stability. It was found to agree with the experimental value within an order of magnitude. In addition, the observed increase of the scaling rate with the increase of particle size was explained by the compensation of the decreased rate of the particle transport by faster decrease of actual particle stability (increase in attachment probability). Therefore the contradiction between the theory and the experiment was resolved for the particles of 20 to 60 nm in diameter. Moreover, the observations of the dimensions and distribution of the scale elements formed in some of the present experiments strongly suggested the significance of the advective (inertial) mechanism of particle deposition. This and comparative analysis of other experimental and theoretical data suggested that the present theory may underestimate the convective transport of the particles onto a rough wall. Therefore, the hypothesis of the parallel-to-wall advective deposition of the nanoparticles onto the roughness/scale elements (not accounted in the current theory) was proposed. The corresponding mass transfer problem was solved analytically using experimentally found dimensions of the scale elements. The additional transport was found to decrease the above-stated discrepancy between the theoretical and experimental scaling rate for large (125 nm) particles by one order of magnitude. The remaining difference of one order of magnitude was speculated to be due to the underestimation of these particles attachment probability derived with the standard DLVO theory. The actual aggregative stability of the silica colloids larger than 60 nm in diameter and for a wider range of IS values is of interest for future experimental studies. An improved understanding of the interrelation between the chemical and hydrodynamic phenomena in the process of silica scaling and its dominant mechanisms was achieved in this dissertation. This allowed optimization of the present anti-scaling practices aimed to minimize the negative effects of mineral scaling on the operation of geothermal power stations. Besides the practical recommendations, which may ultimately help to increase the efficiency of geothermal power stations, the results of the present study may be of value in the fields of mass transfer and colloid science.

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  • Development and optimization of an in vitro process for the production of Oryctes nudivirus in insect cell cultures

    Pushparajan, Charlotte (2015)

    Doctoral thesis
    University of Canterbury Library

    The coconut rhinoceros beetle, an economically important pest of coconut and oil palms, is effectively managed by application of its natural pathogen, the Oryctes nudivirus (OrNV), which act as a bioinsecticide. While this approach offers an environment-friendly alternative to chemical pesticides, the current method of production in infected larvae suffers from inconsistencies in virus productivity and purity. While the anchorage-dependent DSIR-HA-1179 insect cell line has been identified as a susceptible and permissive host for OrNV and therefore would be suitable for the in vitro mass production of the virus, no attempts have been made toward the mass production of the virus, because of the technological challenges that working with DSIR-HA-1179 cells represent. Thus, the main objective of this research was to develop processes for the in vitro production of OrNV in the DSIR-HA-1179 cell line. Knowledge of the growth kinetics and metabolic properties of the host cell line in a chosen culture medium, as well as the selection of an appropriate infection strategy, form the basis for the rational development of bioreactor-based virus production processes. However, characterization of these properties in the DSIR-HA-1179 cell line has been virtually precluded, due to its strongly adherent growth characteristics and the lack of a reliable method to accurately dissociate and count cells grown in monolayers. Using TrypLE™ Express enzyme, a technique allowing the precise counting of cells was developed. The cell line was adapted to grow in four serum-supplemented culture media: TC-100, IPL-41, Sf-900 II and Sf-900 III, which were then individually screened for cell growth and virus production in 25 cm2 attached T-flask cultures. TC-100 supplemented with 10% fetal bovine serum was chosen as a suitable culture medium, based on its capacity for achieving a high cell yield and OrNV production. The cell line metabolism was characterized with respect to nutrient consumption and metabolites production in this culture medium. Glucose, along with glutamine were found to be the nutrients that were consumed faster and to a greater extent, while other amino acids were not consumed to a significant degree. The production of metabolites was characterized by non-production of lactate and ammonia, and production of alanine, as a non-toxic alternative to ammonia. The influence of cell density (CD) at time of infection (TOI) and multiplicity of infection (MOI) on OrNV production was evaluated in T-flask cultures that were infected at different CDs at the TOI and a range of MOIs. The CD at TOI was found to significantly influence OrNV yields, while MOI influenced the dynamics of infection. The cell density effect was found to exist for the DSIR-HA-1179/OrNV system with the progressive decline in cell-specific yield beginning at low cell densities. It was found that in order to maximize OrNV volumetric yield, a combination of MOI and CD at TOI should be selected that allows to keep the maximum cell density reached by the infected culture within a range between 5.0 and 7.0 x 105 viable cells/ml. The roller bottle system was evaluated for its potential to scale-up DSIR-HA-1179 cell growth and OrNV production, and culture parameters were optimized for the improvement of cell and virus yields. An inoculum density of 3.3 x 105 cells/ml and culture volume of 60 ml resulted in the highest cell yield of 1.5 x 106 cells/ml, in 490 cm2 roller bottles. It was found that an optimal infection strategy for roller bottle cultures, which represented the most efficient use of viral inoculum, involved infecting cells at a density of 5.0 x 105 cells/ml and at a MOI of 1. The resulting OrNV volumetric yield of 2.5 x108 TCID50/ml, improved significantly the viral yields obtained in attached T-flask cultures infected under similar conditions (6.8 x 107 TCID50/ml). The microcarrier system was also evaluated for culturing DSIR-HA-1179 cells and producing OrNV in spinner flask bioreactors. Three types of microcarriers (Cytodex-1, Cytodex-3 and Cultispher-G microcarriers) were screened for their ability to support DSIR-HA-1179 growth. Cells attached to Cytodex-1 and 3, but failed to attach to Cultispher-G microcarriers. The final cell density reached in microcarrier culture was dependent on bead type and concentration, and the cell to bead ratio. At an optimal bead concentration of 1 mg/ml and cell to bead ratio of 30, cells grew to a maximum density of 1.7 x 106 cells/ml on Cytodex-1, but only to 1.3 x 106 cells/ml on Cytodex-3 microcarriers. Since it supported higher cell yields, Cytodex-1 was chosen to study the kinetics of OrNV production in this system. Microcarrier cultures infected at a cell density of 5.0 x 105 cells/ml and a MOI of 1, produced OrNV at 1.4 x 108 TCID50/ml, which was higher than the yield obtained in T-flask cultures infected under similar conditions. A framework of knowledge on the physiology, metabolism and growth kinetics of the DSIR-HA-1179 insect cell line has been developed in this thesis. In addition, the feasibility of using roller bottles and microcarrier systems for the in vitro production of the virus has been ascertained. It is envisaged that these findings will contribute to the future development of a large-scale industrial process for the production of the OrNV biopesticide.

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  • Gold-based Nanomaterials: Spectroscopy, Microscopy and Applications in Catalysis and Sensing

    Adnan, Rohul (2015)

    Doctoral thesis
    University of Canterbury Library

    The birth of nanotechnology era has revolutionized materials science, catalysis and field of optoelectronics. Novel and unique phenomena emerge when material dimensions are reduced to ultra-small size regime and enter nanometre (2-100 nm) realm. Such novel materials are expected to replace bulk materials, offering lower cost of manufacturing and enabling progress in many areas such as solar cell, drug delivery, quantum communication and computing, catalysis and sensing applications. With the progress in nanomaterial synthesis and fabrication, the need for the state-of-art characterization techniques became obvious; such techniques help to establish a complete understanding of the nature and interactions of nanosized materials. In this thesis, the first part focuses on the synthesis of gold and ruthenium clusters, namely Au8, Au9, Au101, Ru3, Ru4 and AuRu3, using the well-established synthetic protocols in the literature. Apart from the standard lab-based characterization techniques such as nuclear magnetic resonance (NMR), UV-visible spectroscopy (UV-vis) and Fourier Transform Infra-red (FTIR), a less explored but useful technique far infra-red (far IR) spectroscopy, available at the Australian Synchrotron (AS), was employed to investigate the vibrational modes in these clusters. Peaks in the experimental far IR spectra were assigned unambiguously to specific vibrations by comparing with the ones generated via DFT calculations with the help of collaborators, group of Professor Gregory Metha, University of Adelaide. For the Au9 cluster, three significant gold core vibrations are observed at 157, 177 and 197 cm-1 in the experimental spectrum. In the case of the Ru3 cluster, only a single ruthenium core vibration is identified within the spectrum, at 150 cm-1 with the calculated force constant, k = 0.33 mdyne/Å. The Ru4 cluster exhibits two metal core vibrations at 153 and 170 cm-1 with force constants of 0.35 and 0.53 mdyne/Å, respectively. Substitution with a gold atom yielding a mixed metal AuRu3 cluster shifts the core transitions toward higher wavenumbers at 177 and 299 cm-1 with an increase in force constants to 0.37 and 1.65 mdyne/Å, respectively. This is attributed to the change in chemical composition and geometry of the metal cluster core. A combination of the DFT calculations and high quality synchrotron-based experimental measurements allowed the full assignment of the key transitions in these clusters. Next, these clusters were fabricated into heterogeneous catalysts by depositing on different metal oxide nanopowders. Synchrotron X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) studies were performed at the Australian Synchrotron and the Photon Factory synchrotron in Japan to investigate the electronic structure of Au8, Au9 and Au101 on TiO2 catalysts. The XPS analysis reveals that “as-deposited” Au8 and Au9 retain some un-aggregated clusters while Au101 show bulk-like gold. These findings are in line with TEM observations, where the aggregates (large particles, > 2 nm) of Au8, Au9 and Au101 are hardly seen under HRTEM. UV-visible diffuse reflectance spectroscopy (UV-vis DRS) studies show the absence of localised surface plasmon resonance (LSPR) peaks in these “as-deposited” clusters, suggesting they are below 2 nm in size. Importantly, the XAS spectrum of “as-deposited” Au9 clusters estimates that 60% of pure, un-aggregated Au9 clusters and 40% of bulk gold in the sample. Upon calcination under O2 and combined O2 and H2 (O2-H2), Au8, Au9 and Au101 clusters form larger nanoparticles (> 2 nm) with the appearance of LSPE peak in UV-vis DR spectra. In addition, majority of the phosphine ligands (that stabilise the gold core) dislodge and form phosphine oxide-like species by interacting with oxygen on the TiO2 surface. The third part focused on testing the catalytic performance of the supported Au8, Au9, Au101, Ru3, Ru4 and AuRu3 clusters on different TiO2, SiO2, ZnO and ZrO2 in benzyl alcohol oxidation. Au101-based catalysts display the highest catalytic activity with a turn-over frequency (TOF) up to 0.69 s-1. The high catalytic activity is attributed to the formation of large Au nanoparticles (> 2 nm) that coincides with the partial removal of capping ligands. Au8 and Au9 clusters which contain NO3- counter anions are found to be inactive in benzyl alcohol oxidation. Further work shows that the presence of NO3- species diminishes the catalytic activity. Monometallic ruthenium clusters, Ru3 and Ru4, are found to be inactive yet the bimetallic AuRu3 clusters are active in benzyl alcohol oxidation, suggesting the synergistic effect between ruthenium and gold metal. Investigation of catalytic testing parameters reveals that tuning selectivity of the product is possible through manipulating the reaction temperature. Finally, a joint experiment with Prof. Wojtek Wlodarski’s group at RMIT, Melbourne was undertaken to test the sensing ability of Au9 clusters for hydrogen detection. Au9 clusters were deposited onto radio-frequency (RF) sputtered WO3 films at two different concentrations; 0.01(S1) and 0.1(S2) mg/mL. It was found that the optimal temperatures for sensor S1 and S2 were 300 °C and 350 °C, respectively. The sensor with lower Au9 concentration (S1) displays a faster response and recovery time, and a higher sensitivity toward H2. HRTEM studies reveal that the sensor S1 contain a significant population of sub-5 nm Au nanoparticles which might be responsible for a faster rate of H2 adsorption and dissociation. The key finding in this study suggest that the addition of catalytic layer such as ultra-small Au9 clusters results in improved sensitivity and dynamic performance (response and recovery time) of H2 sensors. In summary, this thesis demonstrated that cluster-based nanomaterials have wide range of applications spanning from catalysis to sensing. Further improvements in material synthesis and use of multiple complimentary characterization techniques allowed better understanding of the nature of the key active species (metal nanoparticles) assisting design of catalysts and sensors with enhanced performance.

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  • Investigation and Prediction of the Sound Transmission Loss of Plywood Constructions

    Wareing, Robin Richard (2015)

    Doctoral thesis
    University of Canterbury Library

    The sound transmission loss of a range of plywood panels was measured to investigate the influence of the orthotropic stiffness of the plywood panels. The plywood panels were tested as single and also double leaf partitions, with a range of stud configurations. A new method was developed for predicting the sound transmission loss of single leaf partitions with both orthotropic and frequency dependent stiffness values. The sound transmission loss was evaluated for two significantly different sample sizes. The observed influence of the sample size on the measured sound transmission loss was profound. The construction of the partition was shown to significantly affect the influence of the sample size on the sound transmission loss. A qualitative analysis based on existing published research of the contributing factors is presented, and methods for adjusting the results for the small sample size for comparison with the large results were developed. The influence of a range of acoustic treatments of lightweight plywood partitions was investigated. The treatments involved internal viscoelastic materials and decoupled mass loaded barriers in various arrangements. The attachment between the treatment and the plywood panel was found to influence the sound transmission loss significantly. A prediction method based on published models was modified to allow the influence of the treatments to be included. Reasonable agreement was achieved between the predicted and measured results for a wide range of samples. A prediction method was developed that accounts for the influence of orthotropic, frequency dependent material parameters. This method utilised an adaptive, numerical integration method to solve an analytical formulation for the sound transmission loss. The influence of the finite sample size was accounted for using an expression for the finite panel radiation impedance. The finite panel radiation impedance was predicted analytically and an approximation was also presented. The presence of a significant source room niche was accounted for by applying an appropriate limit to the integration range of the angle of incidence. The prediction methods developed are compared with the measured transmission loss results from both the small and large test facilities. Good agreement was seen for some of the predicted results. Generally the agreement within the coincidence region was worse than for the rest of the transmission loss curve. The inclusion of orthotropic and frequency dependent stiffness values significantly improved the agreement within the coincidence region.

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  • The collectors : Naval, Army and Air Intelligence in the New Zealand Armed Forces during the Second World War

    Tonkin-Covell, John (2000)

    Doctoral thesis
    University of Waikato

    This thesis examines the performance of the intelligence collection organisations of the armed services of New Zealand during the Second World War. It considers the intelligence bodies of the Navy, the Army and the Air Force and looks at their growth, development and demise, and assesses their effectiveness as intelligence organisations. The question of how much New Zealand could be expected to achieve in the field of intelligence arises, not least because New Zealand was demographically small, had a long coastline and was geographically relatively remote. How much could New Zealand contribute to the Allied cause in intelligence terms is another issue, and what forms did any participation take? Were there lessons to be learned from the wartime experience (there were, but they went for the most part largely unheeded)? New Zealand, like other countries, had a fragmented approach to intelligence collection, making for a degree of complexity over a range of activity, despite the intelligence organisations being of modest size. The examination of the organisations in this thesis includes multi-service and multi-departmental dimensions along with the production of useful intelligence. Whether good use was made of intelligence collected is another matter. There was a substantial amount of liaison, contact and practice between departments of state as to various aspects of intelligence, the Organization for National Security and coastwatching being two notable areas. The overarching role and limitations of the Organization for National Security with regard to intelligence is explored, and the development of a combined intelligence centre examined. The participation of New Zealand signals intelligence organisations in the great Allied interception offensive is detailed, along with the mundane but fundamental task of coastal surveillance. The establishment and spectacular decline of the first local independent security service is traced. Both the intelligence and security aspects of the Army's operationally deployed units are covered, along with the growth of RNZAF air intelligence. The effectiveness of all of these organisations could hardly be expected to be uniform, and indeed it was not. Some bodies succeeded in their collection roles beyond expectations, others were reasonably effective, and two organisations failed dismally in different ways, for a number of reasons. If a pattern emerges at all, it is that small single service component-type intelligence sections collecting operational intelligence were the most effective New Zealand intelligence organisations. Operational focus and. operational requirements underlay the drive for successful collection. Most significant within the Allied context were the signals intelligence bodies. At the other end of the scale, larger co-operative interdepartmental New Zealand intelligence ventures failed to deliver projected results. New Zealand's armed forces had an interesting variety of intelligence contributions during the Second World War. Of these, the most effective organisations collected intelligence to meet directed operational requirements.

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  • El camino se hace caminando: Using Participatory Action Research to evaluate and develop Peace Education practice in a Secondary School in Northern Nicaragua

    Kertyzia, Heather (2015)

    Doctoral thesis
    University of Otago

    Peace education (PE) is included in the cross-curricular themes of the Nicaraguan curriculum, yet in the Secondary School in Northern Nicaragua (SSINN) where this research was conducted there was varied implementation by teachers. The SSINN was selected for this research due to particular problems with violence. Based on a critical and post-development theory perspective and using participatory action research (PAR) methodology, teachers, school psychologists and administrators were led through a facilitated process of reflection upon the culture of peace/violence in the SSINN and teacher practice. This was guided by the concepts of education about (content), for (skills and behaviours) and by peace (pedagogy). PAR is guided by a series of principles that allow for flexibility and response to participant needs. In this case SSINN educators and I engaged in a process of building trust, gathering reconnaissance data, developing action plans and taking action. This was guided by our unofficial motto ‘the path is made by walking’ (el camino se hace caminando), implying that we were learning as we worked together and the process had to be adaptable to new circumstances. Through workshops and coffee chats we evaluated staff definitions of a culture of peace, priorities in relation to peace values, behaviours and content, and teacher practice in regards to peace principles. As part of the reciprocal process, educators gave feedback and directed the research, which was designed to emphasize educator voice and minimize the neo-colonial imposition of values from outside actors. In this way I sought to balance critical theory’s need to take action for positive change with post-development theory’s prioritizing of local educator voice. The primary goals of the research were to develop an understanding of how PE was practised in the SSINN and, if the educators requested it, to provide support in taking positive action for change, while assessing the effectiveness of the PAR methodology. In the beginning the educators had differing definitions of a culture of peace, but they were very consistent in their ideas of what content, skills and values should be included in PE. Although they regularly mentioned problems that were directly relevant to students’ lives that should be addressed in the classroom, not all of the teachers were actively doing this. Due to a lack of resources, time, teacher stress and overcrowding, many teachers were unable to translate those ideas into action. Also due to those factors, many teachers fell into habits of traditional teaching practice that were inconsistent with peace pedagogy. Recognizing these issues, the teachers requested workshops on non-violent communication and conflict transformation in the hope that that knowledge would aid them to more positively manage behaviour. They also created and implemented an action plan. Although positive steps were taken, this was the first stage of a long-term process of change. Partnering with local non-governmental organizations (NGOs) has provided the possibility of the continuation of the process; nevertheless those NGOs have stated that they need continued external support. This flexible PAR methodology was effective at exploring and developing PE practice in the SSINN, and has the potential, if continued, to lead to fundamental positive change.

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  • A multi-modal device for application in microsleep detection

    Knopp, Simon James (2015)

    Doctoral thesis
    University of Canterbury Library

    Microsleeps and other lapses of responsiveness can have severe, or even fatal, consequences for people who must maintain high levels of attention on monotonous tasks for long periods of time, e.g., commercial vehicle drivers, pilots, and air-traffic controllers. This thesis describes a head-mounted system which is the first prototype in the process of creating a system that can detect (and possibly predict) these lapses in real time. The system consists of a wearable device which captures multiple physiological signals from the wearer and an extensible software framework for imple- menting signal processing algorithms. Proof-of-concept algorithms are implemented and used to demonstrate that the system can detect simulated microsleeps in real time. The device has three sensing modalities in order to get a better estimate of the user's cognitive state than by any one alone. Firstly, it has 16 channels of EEG (8 currently in use) captured by 24-bit ADCs sampling at 250 Hz. The EEG is acquired by custom-built dry electrodes consisting of spring-loaded, gold-plated pins. Secondly, the device has a miniature video camera mounted below one eye, providing 320 x 240 px greyscale video of the eye at 60 fps. The camera module includes infrared illumination so that it can operate in the dark. Thirdly, the device has a six-axis IMU to measure the orientation and movement of the head. These sensors are connected to a Gumstix computer-on-module which transmits the captured data to a remote computer via Wi-Fi. The device has a battery life of about 7.4 h. In addition to this hardware, software to receive and analyse data from the head-mounted device was developed. The software is built around a signal processing pipeline that has been designed to encapsulate a wide variety of signal processing algorithms; feature extractors calculate salient properties of the input data and a classifier fuses these features to determine the user's cognitive state. A plug-in system is provided which allows users to write their own signal processing algorithms and to experiment with different combinations of feature extractors and classifiers. Because of this flexible modular design, the system could also be used for applications other than lapse detection‒any application which monitors EEG, eye video, and head movement can be implemented by writing appropriate signal processing plug-ins, e.g., augmented cognition or passive BCIs. The software also provides the ability to configure the device's hardware, to save data to disk, and to monitor the system in real time. Plug-ins can be implemented in C++ or Python. A series of validation tests were carried out to confirm that the system operates as intended. Most of the measured parameters were within the expected ranges: EEG amplifier noise = 0.14 μVRMS input-referred, EEG pass band = DC to 47 Hz, camera focus = 2.4 lp/mm at 40 mm, and total latency < 100 ms. Some parameters were worse than expected but still sufficient for effective operation: EEG amplifier CMRR ≥ 82 dB, EEG cross-talk = -17.4 dB, and IMU sampling rate = 10 Hz. The contact impedance of the dry electrodes, measured to be several hundred kilohms, was too high to obtain clean EEG. Three small-scale experiments were done to test the performance of the device in operation on people. The first two demonstrated that the pupil localization algorithm produces PERCLOS values close to those from a manually-rated gold standard and is robust to changes in ambient light levels, iris colour, and the presence of glasses. The final experiment demonstrated that the system is capable of capturing all three physiological signals, transmitting them to the remote computer in real time, extracting features from each signal, and classifying simulated microsleeps from the extracted features. However, this test was successful only when using conventional wet EEG electrodes instead of the dry electrodes built into the device; it will be necessary to find replacement dry electrodes for the device to be useful. The device and associated software form a platform which other researchers can use to develop algorithms for lapse detection. This platform provides data capture hardware and abstracts away the low-level software details so that other researchers are free to focus solely on developing signal processing techniques. In this way, we hope to enable progress towards a practical real-time, real-world lapse detection system.

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  • Electronic Conduction in Disordered Carbon Materials

    Cheah, Chun Yee (2015)

    Doctoral thesis
    Victoria University of Wellington

    Graphene, consisting of a single layer of carbon atoms, is being widely studied for its interesting fundamental physics and potential applications. The presence and extent of disorder play important roles in determining the electronic conduction mechanism of a conducting material. This thesis presents work on data analysis and modelling of electronic transport mechanisms in disordered carbon materials such as graphene. Based on experimental data of conductance of partially disordered graphene as measured by Gómez-Navarro et al., we propose a model of variable-range hopping (VRH) – defined as quantum tunnelling of charge carriers between localized states – consisting of a crossover from the two-dimensional (2D) electric field-assisted, temperature-driven (Pollak-Riess) VRH to 2D electric field-driven (Skhlovskii) VRH. The novelty of our model is that the temperature-dependent and field-dependent regimes of VRH are unified by a smooth crossover where the slopes of the curves equal at a given temperature. We then derive an analytical expression which allows exact numerical calculation of the crossover fields or voltages. We further extend our crossover model to apply to disordered carbon materials of dimensionalities other than two, namely to the 3D self-assembled carbon networks by Govor et al. and quasi-1D highly-doped conducting polymers by Wang et al. Thus we illustrate the wide applicability of our crossover model to disordered carbon materials of various dimensionalities. We further predict, in analogy to the work of Pollak and Riess, a temperature-assisted, field-driven VRH which aims to extend the field-driven expression of Shklovskii to cases wherein the temperatures are increased. We discover that such an expression gives a good fit to the data until certain limits wherein the temperatures are too high or the applied field too low. In such cases the electronic transport mechanism crosses over to Mott VRH, as expected and analogous to our crossover model described in the previous paragraph. The second part of this thesis details a systematic data analysis and modelling of experimental data of conductance of single-wall carbon nanotube (SWNT) networks prepared by several different chemical-vapour deposition (CVD) methods by Ansaldo et al. and Lima et al. Based on our analysis, we identify and categorize the SWNT networks based on their electronic conduction mechanisms, using various theoretical models which are temperature-dependent and field-dependent. The electronic transport mechanisms of the SWNT networks can be classed into either VRH in one- and two-dimensions or fluctuation-assisted tunnelling (FAT, i.e. interrupted metallic conduction), some with additional resistance from scattering by lattice vibrations. Most notably, for a selected network, we find further evidence for our novel VRH crossover model previously described. We further correlate the electronic transport mechanisms with the morphology of each network based on scanning electron microscopy (SEM) images. We find that SWNT networks which consist of very dense tubes show conduction behaviour consistent with the FAT model, in that they retain a finite and significant fraction of room-temperature conductance as temperatures tend toward absolute zero. On the other hand, SWNT networks which are relatively sparser show conduction behaviour consistent with the VRH model, in that conductance tends to zero as temperatures tend toward absolute zero. We complete our analysis by estimating the average hopping distance for SWNT networks exhibiting VRH conduction, and estimate an indication of the strength of barrier energies and quantum tunnelling for SWNT networks exhibiting FAT conduction.

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  • Investigating the mode of action of tuberculosis drugs using hypersensitive mutants of Mycobacterium smegmatis

    Campen, Richard Laurence (2015)

    Doctoral thesis
    Victoria University of Wellington

    Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB), is the leading cause of death and disease by a bacterial pathogen worldwide. The growing incidence of drug resistant TB, especially multi-drug resistant TB highlights the need for new drugs with novel modes of action. Current treatment of TB involves a multi-drug regimen of four drugs including isoniazid and rifampicin, both of which were discovered over 40 years ago. Bedaquiline is one of the first novel TB drugs to enter clinical trials since the discovery of rifampicin, and has shown excellent activity against drug resistant TB. Although isoniazid and rifampicin are well established anti-TB drugs, significant gaps in knowledge regarding their modes of action exist. Furthermore, little information on the mode of action of the novel drug bedaquiline is known beyond its primary target. Characterisation of drug mode of action facilitates rational modifications of drugs to improve the treatment of TB. The aim of this study was to identify novel aspects of the modes of action of isoniazid, rifampicin, and bedaquiline by characterising drug hypersensitive mutants of M. smegmatis mc²155. A sub-saturated M. smegmatis mc²155 transposon mutant collection with 1.1-fold genome coverage (7680 mutants) was constructed, with this collection estimated to contain mutations in 73.2% of all genes capable of maintaining a transposon insertion (non-essential genes). A high-throughput assay was developed for screening the collection, and mutants related to known drug mode of action were identified for isoniazid (ahpC and eccCa₁) and bedaquiline (atpB). Additionally, known mechanisms of drug inactivation were identified for isoniazid (nudC), rifampicin (arr and lspA), and bedaquiline (mmpL5). The finding that transposon mutants of nudC are hypersensitive to isoniazid independently validated the recent discovery of the role of NudC in basal isoniazid resistance by Wang et al. (2011). The remaining genes identified in this thesis represent potentially novel aspects of the modes of action or resistance mechanisms of these drugs. Cross-sensitivity to other drugs indicated that the mechanism of sensitivity was drug specific for the mutants examined. Differential-sensitivity testing against drug analogues revealed that Arr is involved in resistance to the rifampicin analogue rifapentine as well, indicating that Arr can detoxify rifapentine similar to rifampicin. The nudC mutant showed increased sensitivity to a range of isoniazid analogues, indicating that it can detoxify these analogues similar to the parent compound. Interestingly six analogues were found to be less active against the nudC mutant than expected. A number of overexpression strains were tested against these six analogues; a nudC overexpression strain, and a strain overexpressing inhA, the primary target for isoniazid. Overexpression of nudC as well inhA increased the resistance of WT to isoniazid, but failed to increase resistance to three of the analogues, NSC27607, NSC33759, and NSC40350. Isoniazid is a prodrug and is activated by the peroxidase/catalase enzyme KatG. Overexpression of katG resulted in increased isoniazid sensitivity, as well as increased sensitivity to NSC27607, NSC33759, and NSC40350. Together these results suggest that NSC27607, NSC33759, and NSC40350 are activated by KatG, but that InhA is not the primary target. Additionally the inability of NudC overexpression to confer resistance suggests these analogues are not acting via a NAD adduct, the mechanism by which isoniazid inhibits InhA. These results suggest that there are other toxic metabolites being produced by KatG activation of these three analogues. In conclusion, characterisation of mutants identified in a high-throughput assay for drug hypersensitivity identified genes involved in the modes of action or resistance mechanisms for isoniazid, rifampicin, and bedaquiline. Additionally, a number of novel genes were identified that have no known connections to the known modes of action or resistance mechanisms for these drugs. Further testing of a nudC mutant revealed three isoniazid analogues that appear to inhibit growth of M. smegmatis mc²155 independent of InhA, the primary target of isoniazid. This study has successfully demonstrated that screening for drug hypersensitivity can generate novel information on drug mode of action and resistance mechanisms. This information can ultimately be used to help drive the development of new drugs, and improve treatment of TB.

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  • 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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  • Safe, effective, and patient-specific glycaemic control in neonatal intensive care.

    Dickson, Jennifer Launa (2015)

    Doctoral thesis
    University of Canterbury Library

    Very premature infants often experience high blood sugar levels as a result of incomplete metabolic development, illness, and stress. High blood sugar levels have been associated with a range of worsened outcomes and increased mortality, but debate exists as to whether high blood sugar levels are a cause of, or marker for, these worsened outcomes. Insulin can be used to lower blood sugar levels, but there is no standard protocol for its use in neonates, and the few clinical studies of insulin use in neonatal intensive care are relatively small and/or have resulted in high incidence of dangerously low blood sugar levels. Hence, there is a need for a safe and effective protocol for controlling blood sugar levels to a normal range in order that potential clinical benefits can be successfully studied in this clinical cohort. This thesis adapted a glucose-insulin model successfully used in adult intensive care for the unique physiology and situation of the very premature infant. The model aims to reflect known physiology. As such, sources and disposal of glucose and insulin within the body are examined using both published data and unique data sets from a study here in New Zealand. In addition, the absorption of glucose from milk feeds is examined. This glucose-insulin physiological model is then used alongside statistical forecasting to develop a protocol for selecting an appropriate insulin dose based on targeting of likely outcomes to a specified target normal range. The protocol is tested in silico using virtual trials, and then clinically implemented, with results showing improved performance over current clinical practice and other published studies. In particular, ~77% of blood glucose is observed within the specified target range across the cohort, and there has been no incidence of dangerously low blood glucose levels. This protocol is thus safe and effective, accounting for inter- and intra- patient variability, and thus enabling patient-specific care.

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  • Progesterone and the striatal 6-hydroxydopamine model of Parkinson’s disease

    Perry, James Colin (2015)

    Doctoral thesis
    University of Canterbury Library

    Parkinson’s disease (PD) is a common neurodegenerative disorder that is characterised by akinesia, muscular rigidity, and postural instability, due primarily to the loss of dopaminergic neurons in the substantia nigra and depletion of upstream dopamine in the striatum. Current dopaminergic treatments reduce motor symptoms, but have diminishing benefits as the disease progresses. Treatment with the neuroactive steroid natural progesterone (PROG) improves outcomes in many experimental models of brain injury due to its pleiotropic mechanisms of neuroprotection, many of which may also benefit PD. This thesis investigated the influence of PROG on motor impairments in the unilateral intrastriatal 6-hydroxydopamine (6-OHDA) lesion model of PD in rats. We established a PD-like impairment with a d-amphetamine induced rotation test at day 7 after large lesions and then administered PROG (4 mg/kg or 8 mg/kg) once daily for 7 days starting at day 8. Both PROG doses markedly improved the primary outcome measure, forelimb akinesia on the adjusting steps test, with improvement sustained for six weeks after treatment had stopped. In a second study the beneficial influence of PROG (8 mg/kg) on akinesia was replicated for rats with large lesions and was extended to rats with small lesions so that the latter rats were now similar to sham operated controls. We also found that PROG modestly improved postural instability of the ipsilateral forelimb on the postural instability test, and sensorimotor integration on the whisker test, but did not improve skilled reaching accuracy on a single-pellet reaching task, forelimb use asymmetry on the cylinder test, sensory neglect on the corridor test, or rotation bias after apomorphine. Furthermore, PROG did not change striatal tyrosine hydroxylase density when assessed in rats with large lesions. This study has provided the most thorough examination to date regarding PROG’s influence on motor skills in an animal model of PD. Furthermore, this study has produced novel evidence of the beneficial effects of PROG treatment on forelimb akinesia. These initial promising findings suggest that PROG is an effective therapy for akinesia and thus provides an impetus to further investigate PROG’s efficacy for the treatment of PD.

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  • Development of an aluminium filled epoxy insert using perfactory rapid prototyping technique and electroless nickel plating for low volume plastic injection moulding

    Rajaguru, Janaka Chandraguptha (2015)

    Doctoral thesis
    University of Waikato

    In this research, a rapid tool for low volume production plastic injection moulding is designed, developed, and tested on an injection moulding machine. The tool is designed as a cavity insert of injection mould for plastic parts by an indirect rapid tooling approach. The plastic part is modelled in a CAD system and then built using a Perfactory rapid prototyping (RP) technique. Then a layer of nickel-phosphorous alloy is deposited on the prototype by electroless plating. This nickel plated RP model is then used as a casting pattern. A cavity insert, which is produced by using aluminium filled epoxy resin with the nickel plated casting pattern, is fabricated in a mould base for injection moulding. Experimental testing on the cavity insert using an injection moulding machine show that the tool is producing quality parts without any noticeable deterioration of the surface. The number of shots completed using the cavity insert is more than 600. Applying electroless nickel plating on the casting pattern made of rapid prototyping material was successful. It was found that pre-treatment processes are crucial. In addition, the rapid prototyping material cannot be plated with nickel without palladium activation and stannous sensitising. Results show that the deposited layer is uniform and composed of both nickel and phosphorous. The surface properties of the nickel and phosphorous deposit enhance the plated layer performance due to their low surface roughness and high lubrication characteristics. Moreover, the nickel-phosphorous layer also improves the surface hardness of the cavity insert since it is left on the cavity after the removal of the casting pattern. The cavity insert was installed on an industrial injection moulding machine for trials. Results show that the cavity insert performs well with Polyethylene at 170˚C at an injection pressure in the range of 80 ~ 100 bar. There are no signs of wear and tear on the cavity insert up to 620 shots. However, when the injection pressure is over 120 bar, cracks start developing in the cavity insert followed by catastrophic fracture. This research has shown that manufacturing an indirect rapid tooling using electroless nickel plating for low volume production of plastic injection mouldings is feasible for Perfactory produced RP models. The cavity insert can be fabricated using commonly available low cost materials within 48 hours.

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  • Aspects of the biology of some New Zealand echinoderms : feeding, growth and reproduction in the asteroids, Patiriella regularis (Verrill, 1867) and Coscinasterias calamaria (Gray, 1840).

    Crump, Robin (1969)

    Doctoral thesis
    University of Otago

    192 leaves :illus. ; 30 cm. Bibliography: p.138-147. The author's "The flight response in Struthiolaria papulosa giges Sowerby", reprinted from the New Zealand journal of marine and freshwater research, v.2, no.3, Sept., 1968, in pocket. University of Otago department: Zoology

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  • A Transcriptomic Examination of Sexual Differentiation in Zebrafish, Danio rerio

    Lee, Stephanie Ling Jie (2015)

    Doctoral thesis
    University of Otago

    Zebrafish sex determination and sexual differentiation is complex. Neither sex chromosomes, major sex-determining genes nor universal sex-linked markers have been identified, and a variety of environmental factors can influence sex ratios. It is thus unsurprising that the molecular pathways underpinning zebrafish sexual development remain poorly understood. A few key genes such as, SRY-box containing gene 9a (sox9a), anti-Müllerian hormone (amh), cytochrome P450, family 19, subfamily A, polypeptide 1a (cyp19a1a) are known to play roles in zebrafish gonadal differentiation. However, at this time, there are many more questions than answers about sex determination and differentiation in this ubiquitious, and immensely well-studied, species. As with many other vertebrates, sex hormone treatment can induce sex reversal of gonadal phenotype and sexual behaviour in zebrafish. In this study, we take advantage of hormonal manipulation of sex in developing zebrafish and RNA-Seq to unravel the unknown genetic pathways that underlie sex determination and sexual differentiation. We conducted global transcriptomic profiling of juvenile zebrafish brains and gonads at two important developmental stages in gonadal differentiation: (1) juvenile ovary-to-testis transformation (40 days post fertilization) and (2) the completion of testicular and ovarian differentiation (60 days post fertilization). Gene expression profiles from 17α-methyltestosterone masculinised juvenile zebrafish were also compared with untreated zebrafish to improve understanding of androgenic effects on zebrafish sexual differentiation pathways. To our knowledge, this is the first study profiling transcriptome-wide sex dimorphic gene expression in teleost brains during gonadal differentiation. We identified modest sex differences in developing zebrafish brains; 33 and 185 sex dimorphic genes were identified in the brains of 40 dpf and 60 dpf zebrafish respectively. Methyltestosterone treatment significantly altered expression patterns at both timepoints. We observed a total of 1,554 genes differentially expressed between control female brains and MT-treated brains at 40 dpf. 1,379 genes were differentially expressed between 40 dpf male brains and 40 dpf MT-treated brains. At 60 dpf, 728 genes exhibited differential expression between control female brains and MT-treated brains. Interestingly, significantly fewer genes (269) were differentially expressed between control male brains and MT-treated brains at 60 dpf. In contrast, we observed extensive sex differences in zebrafish gonadal transcriptomes. A total of 5,039 genes were sexually dimorphic at 40 dpf. 2,502 and 2,537 genes were up-regulated in transforming testes and juvenile ovaries respectively. At 60 dpf, we identified 4,190 testis-biased genes and 4,267 ovary-biased genes. Many of the sex dimorphic genes identified have no previous links with gonadal differentiation. Despite accelerated testicular development in MT-treated zebrafish, the numbers of differentially expressed genes identified when control ovaries were compared to control testes or MT-treated testes were similar. We identified 5,237 differentially expressed genes between 40 dpf juvenile ovaries and 40 dpf MT-treated testes. 7,513 genes were differentially expressed between ovaries and MT-treated testes at 60 dpf. There were considerably fewer differences between control testes and MT-treated testes. While 1,222 genes were differentially expressed between control testes and MT-treated testes at 40 dpf, only 20 genes separated the transcriptomes of 60 dpf control testes and MT-treated testes. It appears that androgen-induced masculinization shares key molecular regulators with normal testicular differentiation. A pair of rec8 genes were up-regulated in control testes and MT-treated testes. Testis-biased Rec8 expression was previously reported in mammals. Rec8 is required for sister chromatid cohesion, formation of synaptonemal complexes and homologous recombination during meiosis. To elucidate the functional significance of rec8 genes in testicular development, we characterized rec8 genes in adult zebrafish. Sequence homology, synteny and phylogenetic relationships between the zebrafish rec8 genes were explored in silico. Analysis of rec8a and rec8b gene expression in adult zebrafish confirmed testis-biased expression. Our work sets up a framework for which we can explore further functional testing of zebrafish rec8 genes using morpholino knockdown and CRISPR/Cas knockout technologies.

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  • Rubisco's chiropractor: a study of higher plant Rubisco activase

    Keown, Jeremy Russell (2015)

    Doctoral thesis
    University of Canterbury Library

    Rubisco activase operates as the chaperone responsible for maintaining the catalytic competency of Ribulose 1,5-bisphophate carboxylase oxygenase (Rubisco) in plants. Rubisco is notoriously inefficient, rapidly self-inactivating under physiological conditions. Rubisco activase uses the power released from the hydrolysis of ATP to power a conformational change in Rubisco, reactivating it. Rubisco activase has been previously shown to form a large range of species in solution; however, little has been done to relate the size of oligomeric species and physiological activity. In this thesis data is presented from a range of biophysical techniques including analytical ultracentrifugation, static light scattering, and small angle X-ray scattering combined with activity assays to show a strong relationship between oligomeric state and activity. The results suggest that small oligomers comprising 2-4 subunits are sufficient to attain full specific activity, a highly unusual property for enzymes from the AAA+ family. Studies utilising a number of Rubisco activase variants enabled the determination of how Rubisco and Rubisco activase may interact within a plant cell. A detailed characterisation of the α-, β-, and a mixture of isoforms further broadened our knowledge on the oligomerisation of Rubisco activase. Of particular importance was the discovery of a thermally stable hexameric Rubisco activase variant. It is hoped that these findings may contribute to development of more heat tolerant Rubisco activase and lead research into more drought resilient crop plants.

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