13,074 results for Doctoral

  • Reservoir computing approaches to EEG-based detection of microsleeps.

    Ayyagari, Sudhanshu (2017)

    Doctoral thesis
    University of Canterbury Library

    Long-haul truck drivers, train drivers, and commercial airline pilots routinely experience monotonous and extended driving periods in a sedentary position, which has been associated with drowsiness, microsleeps, and serious accidents. Consequently, the detection and preferably prediction of the microsleeps in subjects working in these high-risk occupations is very important to workplace safety. Therefore, the aim of this project was EEG-based characterization and early detection of microsleeps during a sustained attention task. The overall approach was to identify reliable physiological cues of lapses of sustained attention and microsleeps, to develop a microsleep system which could be used to detect, or better yet, predict the onset of microsleeps in real time and trigger an alert to rouse the user from an impending microsleep. The main motivation of this project was to develop a state-of-the-art lapse detection system by employing novel classifier schemes based on reservoir computing (RC), specifically echo state networks (ESNs) with cascaded-leaky-integrator-neurons and liquid state machines (LSM) to increase current benchmark performances on microsleep detection. This is the first project and study to have implemented and evaluated EEG-based microsleep detection using RC models for the characterization and detection of microsleeps from the underlying EEG. Moreover, the novelty of the ESN-based cascaded-leaky-integrator neuron approach is in its simplicity (as networks with only 8 or less neurons could achieve optimal performance) and its superior microsleep detection performance. In this research, previously collected behavioral EEG data from fifteen healthy male, non-sleep-deprived volunteers performing a 1D-visuomotor tracking task for 1 hour, was used to form classifier models capable of detecting microsleeps with second-scale resolution. The performance of the microsleep detector was measured both in terms of its ability to detect the lapses-of-responsiveness states and microsleep states (in 1-s epochs). The previous lapse detection benchmark performance on this data, used a simple linear discriminant analysis (LDA)-based classifier, fitted with a meta-learner model. This LDA-based system reported the best performance in terms of its mean phi correlation (φ) = 0.39± 0.06, receiver operator characteristics. An epoch length of 2 s and an overlap window of 1 s (50%) between successive epochs were used in the analysis (AUC-ROC) = 0.86 ± 0.03, and precision recall (AUC-PR) = 0.43± 0.09. Models based on EEG power spectra, and power in the traditional bands, were used to detect the changes in the EEG during microsleeps. Normalized EEG epochs with z-scores > 30 were excluded from analysis, resulting in rejection of 8.3% of the epochs. This process was referred to as data pruning. Reduced features from 6 independent feature reduction schemes including, principal components analysis (PCA), kernel PCA (KPCA), probabilistic PCA (PPCA), symmetric neighbourhood embedding (SNE), Nearest neighbour embedding (NNE), and stochastic proximity embedding (SPE) were passed as an input to the classifier models. Classifier models evaluated included the RC-based models including the ESNs with sigmoidal neurons, cascaded ESNs with leaky-integrator neurons and LSMs. The RC-based models were compared to other standard classifier models, such as, support vector machines with polynomial kernel (SVMP), LDA, spiky neural networks (SNN), and k-nearest neighbour (KNN) classifiers. Best microsleep detection was achieved using cascaded ESNs with cascaded-leaky-integrator neurons and 50-60 PCs from PCA of the overall 544 power spectral features. This configuration resulted in φ = 0.51 ± 0.07 (mean ± SE), AUC-ROC = 0.88 ± 0.03, and AUC-PR = 0.44 ± 0.09. LSM-based detectors had a lower performance of φ = 0.42 ± 0.06, AUC-ROC = 0.83 ± 0.03, and AUC-PR = 0.43±0.06, compared to the cascaded-leaky-ESN approach. The PCA-based feature reduction modules showed the highest overall performances of the 6 feature-reduction schemes evaluated. This high performance of PCA-modules was found on all classifier schemes. PPCA-based methods followed the PCA schemes in terms of the best microsleep detection performances. Analysis also showed that creating multiple microsleep detection models (ensemble learning) and combining them to form an overall detector resulted in an improvement in performance over a single classifier model. Microsleep detection was also found to have higher accuracy than the other metrics of flatspots, video microsleeps and definite microsleeps. To study the effect of pruning the data, performances were determined for the classifiers when presented with unpruned data in its entirety for training. Performance was compared with a previous study which used a long short-term memory (LSTM) recurrent neural network (RNN) for which φ = 0.38 ± 0.07, AUC-ROC = 0.84 ± 0.02, and AUC-PR = 0.41 ± 0.08). Similar to the pruned datasets, ESNs with cascaded-leaky-integrator neuron models outperformed all the other classifier schemes and set a new benchmark for EEG-based microsleep detection of φ = 0.44 ± 0.06, AUC-ROC = 0.88 ± 0.04, and AUC-PR = 0.45 ± 0.09. This performance, albeit lower than for the pruned datasets, is deemed the best overall performance for microsleep detection as it was for the full behavioural dataset. In summary, the cascaded-leaky-integrator-ESN approach has provided a new benchmark performance for microsleep detection, which is significantly higher (p = 0.012) than by all previous approaches. Notwithstanding, the performance of these EEG‐based microsleep detection systems is still considered to be modest. Further research is needed to identify additional cues in the EEG leading to devices capable of more accurate detection and prediction of microsleeps.

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  • Research Data Management: An Exploration of the Data Librarian Role in New Zealand Research Organisations

    Ohaji, Isaac Kenechukwu (2016)

    Doctoral thesis
    Victoria University of Wellington

    Modern research practice has been affected by disruptive developments involving technological advancements, for example e-Research and Open Access. These developments imply changes both in the way research is conducted as well as the way research outcomes are communicated. This has huge benefits as well as challenges. The need for researchers to understand how to undertake high quality research in the digital era and how to manage voluminous research data has become critical. To this end, academic librarians, as longstanding custodians of memory institutions and stakeholders to learning and teaching, may play a role in developing this understanding. The study was guided by a model developed from Abbott’s (1988) The System of Professions and the literature. Placed within the constructivist worldview the study adopted a case research approach to explore the dimensions of the data librarian role in four universities and five Crown Research Institutes in New Zealand. The interviewees comprised library managers, library and information professionals, repository managers, researchers and an Information and Technology Services manager. Data from the literature and an exploratory study of five e-Research experts in two Australian universities, and the analysed 43 data librarian position information from relevant websites were triangulated to provide a filter to help interpret the interview data. The Data Librarian Role Blueprint (the Blueprint) emerged from the findings of the study in its three main areas. First, there are factors from national, organisational, research and motivational contexts whose relationships at the level of their components may influence the data librarian role positively or negatively. In terms of performing the role: it was mostly taken to be at the institutional level with subject librarians preferred to be in the role; it has identifiable responsibilities and requirements; and as a specialist individual role, it can exist short-term for purpose of training librarians and in the future when the need or responsibility grows. Finally, training needs for the role were identified in eight areas and the most commonly preferred option to address them was learning on the job through personal and organisational opportunities. There are benefits from the study. For the library and information professionals and those interested in supporting research data management the Blueprint provides a theoretical understanding of the role. The findings are also beneficial to the library and e-Research communities by contributing to the literature in the area and enabling library schools to modernise their curriculum to ensure that graduates relevant to researchers’ needs are produced. However, as the study adopted a single case research design, the findings may not be generalised beyond the case institutions in the study. But, they may provide insight into research data management efforts in places where supporting e-Research and research data management is at infancy or does not yet have any national or institutional direction. Furthermore, the Blueprint may find application or prove to be useful in related research areas.

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  • "Still we live on" : the transfiguration of colonial indentured labour photographs in Mauritius.

    Harrington-Watt, Kathleen (2016)

    Doctoral thesis
    University of Canterbury Library

    Over the last four years I have spent many hours and days researching and viewing the photographic portraits of the Indentured Labour Immigrants of Mauritius (1864 - 1914). My initial engagement with these images felt more like a confrontation with the British Empire and the colonial footprint placed upon its subjects. However, now as I come to the end of this research project and return to my initial thoughts and feelings about the archives, I have noticed that slowly and unwittingly my experience and understanding of these photographs has dramatically shifted from the adversarial stance of where I began. This became most apparent to me when recently presenting a paper on the Indentured Labour Portraits at a visual ethnography conference in Paris. The reactions of the audience to the photographs were reminiscent of my own initial critical colonial perspective. Although my paper at this conference presented a visual methodology that encouraged us to see beyond the negative impressions and assumptions of the colonial archive, the audience nevertheless remained focused on the power of Empire emanating from them. They commented on how hard it was to look at the faces of the labourers and some viewers could not bear to gaze at them for any length of time. Others fixated on the expression of the labourer and their eyes, believing they could sense what the labourer was feeling at the moment the photograph was taken. They described sensing the labourer as scared, frightened, intimidated, and helpless. A feeling of anger and disgust also imbued their comments, thrust clearly at the feet of colonialism. I found these comments unsettling because, for me, four years later, I see and feel different things when I look at the photographs. I have not forgotten their historical beginnings, nor the significance of the colonial construction of this photographic archive, yet what I see more persuasively is the individual story of the labourer. I imagine their trials and tribulations both in India before they came to Mauritius and once they arrived and worked as a labourer on the sugar plantation. I also think about the following generations of their descendants, and all the traditions and rituals they have passed on over time. At the same time, I am in awe of the remarkable endeavour of the photographic system, the photographers, their assistants, and the colonial authority that managed to create such images at such an early period in photography’s history. While reflecting on the conference audience reactions, I felt pangs of guilt for having thoughts of admiration for an exploitative system and for daring to see past the domineering nature of the colonial imprint. My shift in thinking and perspective of the Indentured Labour Portraits has occurred after a long and involved ethnographic encounter with the archives, the images, and the people to whom these photographs have the greatest meaning: the descendants of the indentured labourers. So what does this all mean in relation to my thesis? When I ask myself this question I realise that my own process of engagement with the Indentured Labour Portraits of Mauritius has circled upon itself; the theoretical approaches I have chosen to rely upon are validated by my own research processes, and through a prolonged and in-depth engagement with the photographs, their many dimensions and complex relationships have come to the fore. In essence, by approaching them ethnographically, the controlling purview of their colonial construction has given way to additional knowledge and alternative viewpoints. As such, the ambit of this thesis is not only the social life of the Indentured Labour Portraits, it is also an exploration of how we experience and research photographs, particularly historical images found within colonial archives. Therefore, this thesis is both an introduction and explanation of a valuable colonial photographic archive, as well as a theoretical inquiry into how we engage with photographs in archival research. I do not wish to emphasise one over the other, but rather present them as new sources of knowledge that have emerged from an involved and in-depth study of the photographs and their social world. This thesis represents the Indentured Labour Portrait Archive as found and informed by their Mauritian origin and context. The title of this thesis "Still we live on" – The Transfiguration of Colonial Indentured Labour Photographs in Mauritius, refers to the resilience of the Indentured Labourers and their descendants and the role the Indentured Labour Photographs play in continuing the indentured labour story in Mauritius. The words 'still we live on' come from Deepchand C. Beeharry's novel That Others Might Live (1976). Throughout this thesis I use inserts from Beeharry’s novel as an introduction for most chapters to help keep present the voice of the indentured labourers. Beeharry’s novel deconstructs the imperialist notion of the indentured labourer as the helpless bearer of history, creating a narrative that historicises the indentured labourer as having agency and influence upon their future, and is therefore a powerful source of lyrical text. I use the term 'transfiguration' in the title to signpost the changing form of the Indentured Labour Photographic Portraits from objects of colonial control and exploitation to treasured objects of veneration and honour. Although this thesis is primarily textual, the Indentured Labour Portraits are at the forefront of this dissertation. The prominence of the photographs will be visually displayed at various points throughout this work. A photographic collage will commence each chapter, reminding the reader that it is the encounter with these images that informs this research. Throughout this thesis, I rely upon the photographs to facilitate their own form of engagement and interaction with the reader. There have been many people and organisations involved throughout this research project – most importantly, the descendants of the indentured labourers depicted in these photographs. I hope that this project adds to their continuing curiosity and drive to understand their history and origins.

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  • Interpreting the early Ottoman music repertiore on the oud and nay as recorded in the Ali Ufki and Demetrius Cantemir collections.

    Gemmill, Jonathan (2016)

    Doctoral thesis
    University of Canterbury Library

    In order to inform my own performance on the Middle Eastern lute, the oud, and the flute, the nay, this study aims to discover how court music played in Constantinople4 in the sixteenth century, may have sounded. Is it possible to recreate an authentic performance practice for this repertoire? If this is an achievable goal, how should one approach such a task? Due to the continuity of the maqam music traditions that are in existence today, we do not have to totally recreate an entirely lost and forgotten art. The first thing to undertake is the search for any contemporary musical styles that are linked to the music discussed here. The connections to early Ottoman art music can be found in the current living musical traditions of Persian, East Arabic and Turkish maqam music. These genres will therefore, be thoroughly investigated in order to draw out any stylistic traits of performance practice that are related to early Ottoman music. This study also attempts to bring together aspects contained in the contemporary Turkish, Iranian and Eastern Arabic art music traditions, in order to reassemble aspects of these three modern genres and to create a style of performance practice that unites these three parts into a musical whole. This study is limited to maqam music, that is, the classical art music of the Middle East and Central Asia. The area of maqam music is enormous, and is one of the world’s longest, continuous musical traditions. This study is limited to the Eastern maqam music that is from the fifteenth to sixteenth centuries. The reason for the focus on this period is due to it being a particularly pivotal era in the evolution of the maqam music from this period is the ancestor of today’s Turkish, Arabic and Persian art music. There has been reasonably thorough scholarly attention paid to the Medieval Islamic period and the modern period (nineteenth to twenty-first centuries). Also, Walter Feldman and Eugenia Popescu Judetz have focussed on the seventeenth and eighteenth centuries, and have covered these periods extensively. This study aims to extend the research on the maqam in the fifteenth to sixteenth centuries.

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  • Imagining India as a spiritual place: life-journeys of western spiritual practitioners in Pondicherry.

    Ganguly, Tuhina (2016)

    Doctoral thesis
    University of Canterbury Library

    This thesis is a critical engagement with the ways in which India continues to be constructed as a spiritual place in global imaginaries and transnational discourses of spirituality. Ground in ethnographic fieldwork among primarily North American and Western European spiritual practitioners settled in India, specifically Pondicherry, home to Sri Aurobindo ashram, this research situates their relocation to India within the historical-political trajectories which have constructed the trope, “spiritual India”. The expatriate spiritual practitioners’ narratives of relocating to India offer an antimodernist critique of technological and industrial progress in Western society which, they believe, has led to the destruction of nature, culture, and religion. At the same time, they create India as the site of invoking nostalgia for a premodern lost past of ancient spirituality. This thesis argues and demonstrates that their antimodernism as a response of and to the discontents of modernity is in fact thoroughly modern, albeit exemplifying an alternative modernity. This argument is based on the following: First, the alternative in the form of supposedly premodern India is in itself a modern creation available in the here-and-now due to colonialism, Orientalism, and Indian nationalism (including teachings of religious leaders or gurus). Second, while there is a strong anticonsumerist stance in expatriate spiritual practitioners’ narratives, the romantic turn toward other faiths represents a different kind of consumerism. Third, the alternative proposed is not a return to the glorious past, rather, it is a forward looking vision, following the model of biological evolutionism, in which the modern “ethic of authenticity” finds its full fruition by reconnecting the individual to a divinised world of interconnected authentic selves. Drawing on cross-disciplinary perspectives from Sociology, Anthropology, and Religious Studies on issues of transnational movement of people, global political asymmetries, and modernity, this research contributes to the understanding of spatial and identitarian politics in a global world.

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  • Towards a more effective dispute settlement system in tax treaties.

    Salehifar, Alireza (2016)

    Doctoral thesis
    University of Canterbury Library

    For several years Article 25 of the Model Tax Convention of the Organisation for Economic Co-operation and Development on Income and on Capital (the OECD Model Tax Convention), and Article 25 of the United Nations Model Double Taxation Convention between Developed and Developing Countries (the UN Model Tax Convention) had relied only on a negotiation-based Mutual Agreement Procedure (MAP) as the only mechanism for the resolution of disputes arising from a tax treaty. The MAP, thus, refers to the process of mutual negotiation between tax administrations of the two treaty partners of a Double Tax Agreement (DTA). In this respect, the above model tax conventions have instructed that treaty partners should “endeavour” to resolve their tax disputes through the MAP. Thus, the model tax conventions did not contain any binding legal instrument which could require the treaty partners to finally reach an agreement for the resolution of tax disputes. As a result of this, serious questions have been raised as to the efficiency of the MAP in recent years, leading the OECD to openly acknowledge that there are situations in which cases could not be satisfactorily decided under the MAP process. In order to improve the function of the MAP mechanism, the OECD, in 2008, and the UN Tax Committee, in 2011, have introduced a binding ad hoc arbitration clause in Article 25(5) of their respective model tax conventions. However, the OECD and UN model tax conventions have recognised a very limited role for arbitration in resolving tax treaty disputes. If the treaty partners, during a MAP process, fail to come to an agreement about certain issues within a specific period of time, only then, those unresolved issues can be submitted to arbitration. Arbitration is, therefore, seen as an extension of the MAP process, not as a stand-alone and independent instrument for the resolution of cross-border tax disputes. After establishing that the inclusion of the current arbitration clauses in the OECD and UN model tax conventions have not assuaged the tensions created by divergent interpretation or application of rules espoused in DTAs, this thesis examines possible techniques for improving the dispute resolution system of DTAs and makes suggestions to improve that process.

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  • Te whakarauora reo nō tuawhakarere. Giving our children what we missed out on : Māori language revitalisation for Māori/English bilingualism.

    Martin, Rachel (2016)

    Doctoral thesis
    University of Canterbury Library

    Te reo Māori, the Indigenous language of Aotearoa/New Zealand, is endangered: consequently, it is striving to achieve intergenerational transmission within a dominant English speaking society. This thesis focuses on the relationship between language and identity and the historical and contemporary contexts that have shaped the lives of eight iwi Māori participants and their children, who are living in the realities of this situation. When interviewed, these participants all had children aged between 0 and 5 years and all understood the importance of te reo Māori intergenerational transmission. This thesis seeks to answer the following broad research question: “What emerges from the narratives as Māori parents seek to revitalise Māori language with their children?” Using a Kaupapa Māori theoretical approach and an Indigenous narrative inquiry method, parents’ narratives were gathered and emerging themes were formed from these. Using Benham’s (2007) Indigenous narrative framework for analysis, these emerging themes were first placed into three features: ecological, sociocultural, and institutional. These three features were then scanned for the interrelationships across all three features and further analysed to thereby create a fourth feature, interrelationships. The key findings from this research are that intergenerational te reo Māori is not only about passing on language: it is also about healing intergenerational historical trauma, racial assumptions and stereotypes, which all arise from the legacy of colonisation. These aspects need to be addressed as part of developing both reo Māori communities of support and cultural and spiritual wellbeing so whānau can develop resistant and resilient language identities for living in a contemporary world. Due to high language loss in Ngāi Tahu tribal region (located in the South Island), succession planning is required at all language levels. Rather than relying on institutional knowledge, it is te reo Māori relationships and mentoring systems that will sustain and encourage the use of te reo Māori. This research shows that whānau living the reality of being Māori/English bilinguals have followed a pathway handed down from their ancestors: a pathway which has created a new dynamic way to be bilingual in a contemporary world. The unique contribution of this thesis is to present this pathway in a new model based on these participants’ narratives. This model demonstrates the key roles of whakapapa and rangatiratanga in establishing normalisation of te reo Māori in the home, hapū, iwi, community and civic society. Parents’ experiences and knowledges are valuable as they have led the way in language revitalisation. It is hoped that these research findings and the resulting model will assist Ngāi Tahu with future planning for intergenerational te reo Māori.

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  • The affective element in primary school music education : school music programmes and their influence on children’s attitudes to music.

    Paul, Nicolette (2016)

    Doctoral thesis
    University of Canterbury Library

    tance of monitoring and assessing the development of children’s musical achievement is acknowledged, a prevailing truism for the inclusion of music in the curriculum is to enable children to experience the joy of music. The most significant data on students’ attitude to music arises from the National Education Monitoring Project (NEMP) music survey, administered to samples of Year 4 and Year 8 students four times between 1995 and 2010. That apart, there has been a lack of research into students’ attitudes to music in New Zealand. This study explores the characteristics of four Christchurch primary schools’ music programmes that were identified as examples of best practice. Sources of data include student attitude surveys and semi-structured interviews with key members of staff. In order for data to be compared meaningfully with NEMP data, students in Years 4 and 8 completed a survey with a section replicating the NEMP music survey. Data were also collected on the reasons for and extent of student participation in musical opportunities in and out of school. The range of opportunities provided at each school were aligned with a modified version of the taxonomy of the affective domain (Krathwohl, Bloom & Masia, 1964) to consider the theoretical potential of each school’s music programme to encourage students’ affective development along a continuum. Information collected in this study reveals diversity in how music is delivered to students across the four settings, with the provision of specialised programmes for able or motivated students and compulsory general music being a point of difference. Students at schools in which music was a compulsory component of the school’s curriculum demonstrated more positive attitudes than where music was an elective activity only. The study documents practices in schools following changes to curriculum, including the amalgamation of the arts and the introduction of National Standards. The outcomes suggest that opportunities to learn music may be linked to affective development in music and that there are benefits for both able and less able students when every child is engaged in the music programme.

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  • Model-based hemodynamic monitoring in critical care for improved diagnosis and treatment.

    Kamoi, Shun (2016)

    Doctoral thesis
    University of Canterbury Library

    Cardiac and circulatory dysfunction are leading causes of admission, cost, and mortality in the intensive care unit (ICU). However, choosing a suitable treatment is extremely difficult, as a wide range of complex and patient-specific dysfunction types are found. Furthermore, due to the limits and constraints on the currently obtainable data, a full, clear picture of patient state cannot be precisely delineated, which can result in misdiagnosis and incorrect treatment choices. To overcome this problem, cardiovascular parameters essential for correct diagnosis and treatment must be accurately estimated from clinically available measured data. Specifically, the volume of blood ejected from the heart per beat, known as stroke volume (SV), needs to be estimated from easily accessible measurements, such as blood pressure, as it is an important hemodynamic parameter for assessment of cardiovascular performance. This goal can be accomplished by “adding value” to existing clinical data using physiological models of the cardiovascular system. This research develops a novel aortic model and patient-specific hemodynamic parameter identification method for continuous and accurate estimation of SV using measurements commonly available in the ICU. Thus, SV can be acquired in a non-additionally invasive fashion. In addition, use of this SV measurement can enhance the diagnosis, treatment and therapeutic decision support of bedside clinicians. The aortic model developed in this thesis uses continuous aortic pressure waveform and pulse wave velocity (PWV) as inputs to estimate SV. The parameters within the aortic model are aortic characteristic impedance, aortic compliance, and systemic resistance, and are identified beat-to-beat. These parameters are used to compute blood flow and thus to estimate SV for every heartbeat. The SV estimation method is validated with two series of pig experiments involving administration of dobutamine and inducing septic shock, where direct and invasive measurement of SV is obtained for a gold standard comparator. In addition, SV is significantly changed throughout the experiment by modifying preload using various levels of positive end expiratory pressure, as well as fluid administration. The method developed is also compared against the PiCCO system from PULSION, a commercially available pressure-based SV estimation device that is currently considered the most accurate in the critical care. The Bland-Altman results from the porcine study showed clinically acceptable accuracy within approximately ± 30% by the developed model. The PiCCO system also showed similar accuracy compared with the direct SV measurement. However, the PiCCO system required multiple calibrations during the pig study, while the developed method only required one. This result suggests that the developed model and methods are more accurate and clinically useful, particularly when hemodynamic instability is present. Overall, the model developed in this research shows great potential for improving patient care in the ICU. The model offers key hemodynamic parameters for optimizing cardiovascular treatment. In particular, accurate titration of fluid, inotropes, and vasoactive drugs to patient specific responses are now possible. The overall methods and model can be generalized to outpatient management. The overall outcome provide new opportunities to reduce the cost of care, while improving quality. Adding value to existing measurements has not previously been proven in circulartory management. Hence, this research provides a template for further advances, particularly in the highly monitored critical environment.

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  • Mental health and factors related to mental health among Pakistani university students.

    Irfan, Uzma (2016)

    Doctoral thesis
    University of Canterbury Library

    This study investigated potential factors contributing to mental health in university students in Pakistan. The specific factors selected for investigation were fathers warmth, extraversion vs. introversion, self-esteem, and peer relationships. Two demographic factors, gender and socio-economic status (based on parental income), were also examined to determine potential relationships with mental health problems. A quantitative research design was utilized and data were obtained through participants completing five different standardized surveys. The participants were 314 undergraduate students from different departments, attending one university in Karachi. The age of participants ranged from 18 to 24 years, and 149 were female and 165 were male. The findings of this study revealed a positive correlation between extraversion and mental health, fathers warmth and mental health, and self-esteem and mental health, along with significant gender differences: male students reported more positive mental health levels than female students. There was also a trend for those students from the lowest parental income category to report lower mental health levels. Additionally, of the factors assessed, fathers warmth predicted most variabilityin mental health scores. These findings provide insights into students perception of their mental health and factors that maybe related to these self-reports. Such work highlights the importance of raising awareness of mental health among university students, their families, and university administration, particularly in cultures where these is potentially less acceptance of mental health problems. The findings should support the planning and development of effective interventions and strategies, not only for university students experiencing mental health problems, but also universityadministration: the influence of fathers warmth on mental health self-reports in this context suggests a need to consider parental involvement in effective interventions, for example. Findings are also discussed in terms of potential gender differences and cultural factors that influence students perceptions of their psychological well-being.

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  • In vitro selection and characterisation of iron-efficient potato cell lines

    Addae Boamponsem, Georgina (2016)

    Doctoral thesis
    University of Canterbury Library

    Iron (Fe) is an essential micronutrient involved in life-sustaining biochemical processes including photosynthesis, DNA synthesis and repair, antioxidative defence, hormone synthesis and respiration. Fe bioavailability, however, is a major constraint for crop production due to low Fe solubility resulting from multiple soil and /or biochemical stresses. Iron deficiency-induced chlorosis (IDC) is a widespread nutritional disorder in plants worldwide especially in calcareous soils. To reduce the economic impact of Fe-deficiency stress, it has become necessary to deploy in vitro tissue culture as a quick and cost-effective tool for developing stress-tolerant plants. The development of IDC-tolerant (Fe-efficient) plants presents an important means of alleviating IDC. The aim of the present study was to investigate the hypothesis that using in vitro selection, it would be possible to exploit somaclonal variation and the inherent ability of plants to evolve adaptive mechanisms under Fe-deficiency stress for the generation of novel Fe-efficient potato plant lines. To achieve this, an in vitro selection strategy was designed to generate putative Fe-efficient potato (Solanum tuberosum cv ‘Iwa’) cell lines and plants were regenerated from these cell lines. The Fe-efficient plant lines derived from these cell lines were characterised, using various morphological, biochemical and molecular parameters, regarding their responses to Fedeficiency under in vitro conditions. A two‐step direct selection scheme employing Fe deficiency (0-5 µM) as selective pressure was applied in generating novel Fe-efficient somaclonal variants. Fe-efficient callus cells were selected on half-strength Murashige and Skoog (MS) medium supplemented with 1.78 µM N₆-benzylaminopurine (BA), 3.22 µM α-naphthaleneacetic acid (NAA) and 0-5 µM FeNaEDTA. Shoot buds were regenerated from the calli exhibiting IDC tolerance when cultured on half-strength MS medium supplemented with 6.66 µM BA and 2.89 µM gibberellic acid (GA₃) and 35 plant lines were established. The IDC tolerance of the 35 plant lines was confirmed when they were grown on plant growth regulator-free medium supplemented with 0-5 µM FeNaEDTA. Using IDC scores as the evaluation criteria, 23% of the plant lines (8) could be regarded as Fe-efficient and 77% (27) as Fe-inefficient plant lines. The compact potato callus cultures produced were used to investigate more closely their responses to a short-term (1 month) and an extended period (3 months) of a Fe deficit or sufficiency in the culture medium. The morphological responses include visual chlorotic symptoms (yellowing), reduced fresh weight and area of growth covered by calli grown on Fe-deficient medium. A Fe deficit in the medium led to decreases in chlorophyll and carotenoid contents, reduction in activities of peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) enzymes accompanied with an increase in lipid peroxidation in calli. Exposure of calli to Fe deficiency enhanced ferric chelate reductase (FCR) activity, induced phenolic production and increased hydrogen peroxide (H₂O₂) generation. Histochemical staining of Fe showed that whereas Fe distribution in cells of calli cultured on Fe-deficient medium was sparse, Fe was widely distributed among actively dividing callus cells cultured on Fe-sufficient medium. The morphological and biochemical responses assessed were pronounced with prolonged exposure to Fe deficiency leading to severe chlorosis and/or death of cells in chlorosis-susceptible calli but chlorosis-tolerant calli cells maintained their greenness and viability. These findings have contributed to a better understanding of Fe nutrition in potato at the cellular level. The morphological, biochemical and molecular mechanisms conferring differential tolerance to Fe deficiency in two contrasting groups of potato plant lines established in this study were characterised. Fe-inefficient (INF) plant lines and control plants exhibited severe chlorosis when grown on a Fe-limiting medium, but Fe-efficient (EF) lines were tolerant to chlorosis. The EF plant lines were of shorter statures as far as stem height, root length, internodal distances were concerned compared to INF and control plants. Formation of lateral roots and root hairs was enhanced in EF plant lines compared to INF and control plants, suggesting that these might be morphological adaptations in the root of the EF plant lines in response to a deficit in Fe supply. There was a significantly positive correlation between chlorosis score and root length in control plants and INF plant lines, indicating that root length could contribute to IDC susceptibility. Furthermore, stem height was found to have a highly positive relationship with intermodal distance, leaf and root lengths in EF plant lines. Biochemically, IDC tolerance was linked to increased chlorophyll contents, FCR and POD enzyme activities in the leaves of EF plant lines. The absence of a similar adaptive strategy in leaves of INF lines could underpin their susceptibility to Fe deficiency conditions. FCR and POD activities in the roots of EF plant lines increased greatly while chlorophyll content decreased. The reverse was observed in the roots of INF plant lines, implying that the aforementioned responses contributed to Fe-efficiency at the root level. Increased POD activities in both roots and leaves of EF plant lines suggest that improved capacity to detoxify ROS plays a role to adapt to Fe deficiency stress. Leaf carotenoid content was highly variable among EF and INF plant lines but the carotenoid content decreased in the roots of EF compared to INF plant lines. It would seem that carotenoid content in the roots rather than the leaves might be a more suitable indicator for assessing differential tolerance to IDC. Fe deficiency resulted in the reduction in phenolic concentration in roots and leaves of IFN and some EF plant lines relative to control plants. However, 40-50% of the EF lines (A1, B2, E13) showed higher amounts of phenolics in roots and/or leaves. The findings suggest that IDC tolerance is related to improvement in ferric reductase ability, regulation of chlorophyll biosynthesis and enhancement of the antioxidant potentials. These parameters may serve as predictors for Fe-efficiency trait in plants. Transcriptional responses of both sets of potato plant lines provide evidence that ferritin (FER3) and the iron-regulated transporter (IRT1) play a role in the acquisition of iron from sources with low bioavailability mainly in the leaves and roots respectively. The A1 chlorosis-tolerant plant line exhibited characteristic Fe-efficiency responses of increased fer3 and irt1 transcripts in leaf and root organs. Significantly increased fer3 expression was detected in the leaves of a higher proportion (62%) of putative Fe-efficient lines than in roots (37.5%). IRT1 expression level was 20% significantly greater in roots than in leaves. IRT1 transcripts in the roots of 50% of the potential EF plant lines (A1, B2, B9, E3) was enhanced in response to Fe deficiency. Some IFN plants had higher values of gene expression compared to EF plants. In conclusion, a novel set of Fe-efficient and inefficient potato plant lines has been developed which can be useful in further research and breeding programs aiming at selecting IDC tolerant potato genotypes. Taken together, the results showed that 37.5% of the putative EF plant lines (A1, B2, B9) have both the capacity to elicit improved morphological and biochemical characteristics in responses to Fe-deficiency stress as well as to enhance the expression of Fe homeostasis-related genes. The in vitro selection approach used in this study can be applied for the selection of Fe-efficiency in other plant species.

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  • Quantifying the benefits from the spatial diversification of wind power in New Zealand.

    McQueen, Dougal (2016)

    Doctoral thesis
    University of Canterbury Library

    Wind power is one of the least cost forms of electricity generation, which along with the need to reduce carbon emissions, means that wind power capacity will certainly increase. The turbulent nature of wind and the passive reaction of wind turbines ensures that wind power is variable. The variability in power increases the requirement for system reserves to ensure power quality is maintained. Integration studies are undertaken to determine what impact wind power development will have on the power system and an often reached conclusion is that spatial diversification can alleviate some of the impacts. However, many of these studies fall short of quantifying the benefit of spatial diversification. To quantify that benefit requires models of wind power that are spatially and temporally consistent and congruent with other forms of generation and demand. In this thesis a wind power model is formed, starting with wind speed time-series from the European Centre for Medium-range Weather Forecasting reanalysis which are interpolated, scaled and imputed. The imputation requires a model of turbulence and a Wavelet Multi-resolution Analysis model is developed that accounts for the heteroskedasticity of wind while enforcing the correct temporal and spatial correlations. The wind speed time-series are transformed to power using wind power plant power curves. A Low Pass Filter is developed that accounts for the effect of spatial integration performed by Wind Power Plants. To demonstrate the benefit of spatial diversification in the New Zealand power system four scenarios are developed representing 2GW wind power portfolios. The scenarios are Compact, Disperse, Diverse, and Business As Usual (BAU). Metrics for reliability, variability, and predictability are defined that reflect the structure of the New Zealand Electricity Market. Reliability is assessed using the standard deviation of power. Variability is assessed using ramp rates over a 5 minute period which equates with the window used for reserves scheduling. Predictability is assessed using persistence forecast errors over 2 hour horizons which equates with the gate closure in the New Zealand Electricity Market. The conclusion is that a compact wind generation portfolio will exhibit lower reliability, a diverse portfolio will exhibit less variability, and a disperse portfolio will exhibit greater predictability. The BAU scenario shows that the existing portfolio of Wind Power Plants in New Zealand achieves some of the benefits of spatial diversification, however greater benefit could be achieved through careful planning. This thesis forms part of Research Aim 1.1.1 of the GREEN Grid project.

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  • Influence of inferential skills on the reading comprehension ability of adult Thai (L1) and English (L2) students.

    Srisang, Pawadee (2017)

    Doctoral thesis
    University of Canterbury Library

    The ability to make inferences from linguistic information (spoken and written discourse) is regarded as a significant factor in successful reading success. Although, this relationship has been researched with English first language/monolingual cohorts (see Cain, Oakhill, Barnes, & Bryant, 2001; Oakhill & Cain, 2012; Silva & Cain, 2015), there is a paucity of research on inferential skills in other languages as well as in bilinguals or second language learning contexts. Therefore, the present study focused on investigating inferential skills and reading comprehension in two different languages (Thai and English) within the same group of adult students at a college in Thailand. The primary objectives of this study, as reported in this thesis, were to examine the reciprocal relationships of inferential skills within Thai and English, and to investigate whether inferential skills can predict reading comprehension both within each language and across languages (Thai-L1 and English-L2). The study involved measures of inferential skills, reading comprehension, vocabulary and listening comprehension in Thai and English, following appropriate adaptation, piloting and revision. Raven’s Advanced Progressive Matrices test (short form) was also used to explore non verbal reasoning, and a questionnaire was used to provide background details about the participants and their views on reading comprehension strategies. Data collection was conducted at one campus of a university in Thailand. All ten measures were administered to a group of 220 Thai undergraduate students. The results demonstrated a significant inter-relationship between inferential skills in Thai (L1) and English (L2). Scores on the inferential tasks were also related to reading comprehension within the same language. Furthermore, the findings from hierarchical regression analyses indicated that the addition of inferential skill scores significantly increased the predictability of reading comprehension in the same language, after controlling for within-language vocabulary levels (and listening comprehension in the case of Thai) and non-verbal reasoning. Analyses across languages showed positive correlations between Thai inferential skills and English reading comprehension, and between English inferential skills and Thai reading comprehension. Hierarchical regression analyses indicated that the addition of English inferential skills scores predicted extra variability in Thai reading comprehension, after controlling for English and Thai language related skills and non-verbal reasoning measures, but the addition of Thai inferential skills scores did not influence the level of prediction of English reading comprehension after controlling for the same variables. The reading strategies questionnaire did not reveal a significant relationship with either the Thai or the English reading comprehension scores. However, relationships between self-reported reading comprehension strategies and inferential skills scores were found, though the correlations were relatively small. Overall, the findings are consistent with the ability to make inferences being an important component of successful text comprehension–although there is little evidence of awareness influencing performance among the current participants. The influence of inference making does not seem to be explained by more general language skills (such as vocabulary and listening comprehension), nor by more general (non-verbal) reasoning skills, and it has the potential to occur across languages (from English to Thai in the present study), although within language influences may be larger than between languages. These findings have both theoretical and practical implications, which are discussed in this thesis.

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  • Non-slagging entrained flow gasification of pyrolysis oil from radiata pine woody biomass.

    Abdul Patah, Muhamad Fazly (2016)

    Doctoral thesis
    University of Canterbury Library

    A pilot scale non-slagging entrained flow (EF) gasification system was developed to gasify biomass pyrolysis oil using oxygen as the gasification agent. The pyrolysis oil was derived from New Zealand radiata pine wood chips through a fast pyrolysis process. The oil was fed into the system through an external mix twin-fluid atomizer which is capable of generating fine oil droplets after impact with the oxygen gas. Gasification was conducted at atmospheric pressure while the operation temperatures were dependent on the heat generated from partial combustion of pyrolysis oil with oxygen upon leaving the atomizer. Cold model experiments were first performed to investigate the effect of pyrolysis oil and gas flow rates on atomization performance. The use of external mix atomizer in this work is advantageous as it allows superior control of atomization performance by independent adjustments of pyrolysis oil and oxygen flow rates. Results from this cold model experiments show both flow rates of pyrolysis oil and oxygen gas have distinct influence on the resulted spray characteristics and consequently gasification performance. Increase in pyrolysis oil flow rate has negative influence on spray characteristics as larger droplet size and less uniform spray are generated. On the other hand, atomization at high gas flow rate substantially improves spray characteristics by production of more uniform spray and smaller droplets. The combined effect of pyrolysis oil and gas flow rates is reflected by the gas-to-fuel ratio (GFR) where higher GFR values indicate higher atomization performance and therefore better spray characteristics. After the cold model experiments, entrained flow gasification of pyrolysis oil were conducted to investigate effects of different gasification conditions on producer gas composition, gas yield, tar species distributions and total tar content in the producer gas. When equivalence ratio (ER) was increased during gasification at constant oxygen flow rate, concentrations of H2, CO and CO2 in the producer gas changed in parabolic trends, which is unique compared to linear relationships usually reported in the literature. Below the critical ER value, the H2 and CO concentrations increase while the CO2 concentration decreases with increasing equivalence ratio. However when the equivalence ratio exceeds the critical value, the opposite trends are observed. The critical ER during gasification at oxygen feeding rate of 900 L/h occurred at equivalence ratio of 0.3. At this condition, the maximum concentrations of H2 and CO were at 22 vol% and 36 vol% respectively while the minimum concentration of CO2 was measured at 33 vol%. The changes in producer gas trends with equivalence ratio relates to the continuous improvements in the spray characteristics and increase in the process residence time as the equivalence ratio increases. At constant oxygen flow rate, higher ER value is obtained by decreasing pyrolysis oil feeding into the system, which corresponds to higher GFR value thus better spray characteristics. The decline in pyrolysis oil feeding also results production of less producer gas which reduces its velocity and consequently increases the process residence time. Investigation on influence of increasing oxygen flow rate during gasification at constant ER was also performed in which the oxygen flow rate was varied between 600 L/h, 900 L/h, 1500 L/h and 3000 L/h in separate sets of experiments. Results from these experiments proved that at a given ER, gasification with high oxygen flow rate is highly desirable due to the substantial improvements in the oil spray characteristics and mixing behaviour that consequently leads to better overall reaction kinetics in the system. In addition to that, increase in the gasification temperature during gasification at high oxygen flow rates also help drive the system closer to equilibrium state which favours H2 and CO concentrations in the product. Increase of oxygen flow rate from 900 L/h to 1500L/h during gasification was observed to shift the critical ER value from 0.3 to 0.5 at which the maximum H2 and CO concentrations were also increased from 22 vol% to 28 vol% and from 36 vol% to 41 vol% respectively. On the other hand CO2 concentration declined from 33 vol% to 27 vol% when the oxygen flow rate was increased. In general, at high ER values, higher oxygen and pyrolysis oil flow rates favour producer gas quality with higher concentrations of H2 and CO but lower concentrations of CO2. However, at low ER values, the producer gas from gasification at higher oxygen and pyrolysis oil flow rates consists of lower concentrations of H2 and CO but higher concentration of CO2. As the residence time increases at increasing equivalence ratio, pyrolysis oil conversion improves more rapidly during gasification at 1500 L/h than that at 900 L/h thus giving more rapid growth in H2 and CO concentrations in the producer gas. These results are related to the effects of varying oxygen and pyrolysis oil flow rates on both spay characteristics and residence time. From analysis of tar in the producer gas, it was found that the total tar content in the producer gas decreased as the equivalence ratio was increased. In all cases investigated in this work, light polyaromatic hydrocarbon (PAH) compounds form the largest fractions of the tar components which accounts up to 78 wt% of the total tar in the producer gas. Detailed investigation into the tar individual species revealed naphthalene as the single most abundant tar species in the system which contributed as much as 36 wt% of the total tar in the producer gas. Results from this analysis also confirm that the methods used for tar sampling and analyses adopted in this work are capable of capturing and analysing tar compounds in the producer gas.

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  • Thriving after trauma : a study of posttraumatic growth amongst resilient residents of Christchurch, New Zealand, after the 2010 and 2011 earthquakes.

    Smith, Rebekah (2015)

    Doctoral thesis
    University of Canterbury Library

    Research on responses to trauma has historically focused on the negative repercussions of a struggle with adversity. However, more recently, researchers have begun to examine posttraumatic growth: the positive psychological change that emerges from the struggle with a potentially traumatic event. Associations have been found between posttraumatic growth and greater peritraumatic distress, greater objective severity of trauma exposure, greater perceived stressfulness of events, social support, female gender, cognitive and behavioural responses to trauma, and personality measures. Posttraumatic growth has been measured typically in individuals with varying levels of posttraumatic stress disorder symptoms and other psychological difficulties, such as depression and anxiety. Although some theory and research posits that higher resilience would prohibit posttraumatic growth, no studies have examined posttraumatic growth in a resilient sample. The Canterbury earthquake sequence of 2010 and 2011 involved potentially traumatic events that saw the community struggle with a variety of challenges. However, in the midst of earthquake destruction, some positive initiatives emerged, driven by locals. The Gap Filler project (using city spaces left empty from fallen buildings for art and interactive community projects) and the Student Volunteer Army (groups of volunteers coordinated to help others in need) are examples of this. In this context, it seemed likely that posttraumatic growth was occurring and might be seen in individuals who were coping well with challenges. Culture is theorised to influence the posttraumatic growth process (Calhoun, Cann, & Tedeschi, 2010), and the nature of the trauma undergone is also likely to influence the process of growth. The current thesis measures posttraumatic growth quantitatively and qualitatively in a New Zealand sample. It measures and describes posttraumatic growth in a resilient population after the earthquake sequence of 2010 and 2011 in Canterbury, New Zealand. Findings are used to test current models of posttraumatic growth for individuals coping well after trauma and to elaborate on mechanisms proposed by models such as the comprehensive model of posttraumatic growth (Calhoun et al., 2010) and the organismic valuing theory of growth through adversity (Joseph & Linley, 2005). Correlates of posttraumatic growth are examined and likely supporting factors of posttraumatic growth are identified for this population. Study 1 used quantitative analysis to explore correlates of posttraumatic growth and found that greater posttraumatic growth related to greater peritraumatic distress, greater perceived stressfulness of earthquake events, greater objective stressfulness of earthquake events, greater difficulty with stressful life events, less satisfaction with social support, and female gender. Findings from Study 1 give important detail about the nature of distress included in the comprehensive model of posttraumatic growth (Calhoun et al., 2010) for this population. Levels of posttraumatic growth were lower than those in North American studies but similar to those in a Chinese study. The current sample, however, showed lower endorsement of Relating to Others than the Chinese study, perhaps because of cultural differences. Study 2 used qualitative analysis to examine the experience of posttraumatic growth in the sample. The theme of ‘a greater sense of community’ was found and adds to the comprehensive model of posttraumatic growth, in that an expression of posttraumatic growth (a greater connection with others) can inform ongoing social processing in the posttraumatic growth process. Having a formal or informal role in earthquake recovery appeared to influence self-concept and reflection; this elaborates on the influence of role on reflection in Calhoun et al.’s model. Findings illustrate possible mechanisms of the organismic valuing process theorised by Joseph and Linley (2005). Implications include the importance of providing opportunities for individuals to take on a role after a crisis, encouraging them to act to respond to difficulties, and encouraging them to meet personal needs for relatedness, competence, and autonomy. Finding positive aspects to a difficult situation, as well as acknowledging adversity, can be supported in future to help individuals process their traumas. As a society, we can help individuals cope with adversity by providing ways they can meet their needs for relatedness, competence, and autonomy. Community groups likely provide opportunities for members to act in ways that meet such needs. This will allow them to effectively act to meet their needs in times of crisis.

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  • Structural, dynamic and interaction studies of autophagy-related proteins.

    Ravichandran, Arvind Chand (2016)

    Doctoral thesis
    University of Canterbury Library

    Autophagy is a crucial cellular catabolic process that degrades unwanted cytoplasmic material (cargo) by engulfing the material into a double-membrane vesicle (autophagosome) and then presenting it to the lysosome. The work in this thesis explores interactions between the proteins involved in the autophagy pathway. Focal adhesion complex Interacting Protein of 200 kDa (FIP200) and autophagy related protein 13 (Atg13) are members of the autophagy initiation complex. Attempts were made to locate the region on FIP200 that binds the Atg13 by dividing FIP200 into six fragments of equal length and performing pull-down assays with Atg13. However, because of a false positive interaction observed for all six FIP200 fragments, binding between the Atg13- interaction region on FIP200 and Atg13 could not be identified. Pleckstrin homology domain-containing protein family member 1 (PLEKHM1) is a selective autophagy receptor that interacts with the autophagy-related protein 8 homologues (Atg8 proteins: LC3A, LC3B, LC3C and GABARAP, GABARAPL1, GABARAPL2). The affinity of PLEKHM1 for the LC3 family is higher than that for the GABARAP family of proteins. The Atg8 proteins are involved in tethering cargo to the autophagosome. The crystal structures of five human ATG8 proteins were solved in complex with a peptide with the sequence of the PLEKHM1 LC3-Interacting Region (LIR) to understand the structural basis of their differing binding affinities. These structures demonstrated that residues Arg28 and Glu17 of the GABARAP family proteins interact with Asn637 and Trp635 residues of the PLEKHM1 LIR peptide. However, these interactions were either weak or not present in the LC3 family proteins, suggesting that they may contribute to the higher binding affinity for the PLEKHM1 LIR observed with GABARAP proteins. In addition, a structural comparison of the human ATG8 proteins suggested that the “W-site” hydrophobic pocket, where Trp635 in PLEKHM1 binds, is deeper in GABARAP family proteins than in LC3 family proteins. Together, the structural analysis provided a rationale for varying binding affinities between GABARAP and LC3 family proteins. The serine/threonine-protein kinase ULK1, which is part of the autophagy initiation complex, also interacts with the Atg8 family proteins. Using surface plasmon resonance, molecular dynamic (MD) simulations, mutational analysis and X-ray crystallography, the interaction of the ULK1 LIR with GABARAP and LC3A was studied to understand the difference in the LIR interaction mechanism. Structural comparison of the LC3A and GABARAP proteins in their LIR-bound and unbound states showed that LC3A shows more variation in the structure of its “W-site” hydrophobic pocket between its bound and unbound states than the “W-site” of GABARAP. This was verified by MD simulations. Additionally, the MD simulations suggested an electrostatic interaction between LC3A Arg70 and ULK1 Met359. This was demonstrated by the decrease in binding affinity when Arg70 was mutated to leucine. In contrast, mutation of Arg67 (which is equivalent to Arg70 in LC3A) to leucine did not have any effect on LIR binding. Overall, this work provides key insights into the differences in the mechanisms of interaction demonstrated by the GABARAP and LC3 family proteins, which is an initial step towards understanding the different functions of the members of the two human ATG8 subfamilies (GABARAP and LC3).

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  • Impacts of volcanic ash on surface transportation networks : considerations for Auckland City, New Zealand.

    Blake, Daniel Mark (2016)

    Doctoral thesis
    University of Canterbury Library

    Volcanic eruptions can cause a variety of impacts on critical infrastructure through a multitude of accompanying hazards. Impacts from volcanic ash can be highly disruptive, widespread and longlasting, with substantial consequences for society. With a growing worldwide population and associated expansion of complex critical infrastructure networks in volcanically active areas, volcanic risk assessments are more important than ever. However, there are many challenges, particularly as research developments in the discipline are relatively recent; many opportunities for improved understanding remain. Transportation is arguably the most crucial type of critical infrastructure during volcanic eruptions as it may be required for a variety of response and recovery activities, including the maintenance and restoration of all other critical infrastructure. In long-lasting eruptions, people may live with volcanic ash for months to years and use transportation networks affected by ash on a daily basis. Although there are many observations of surface transportation impacts following previous eruptions, vulnerability data has been largely qualitative and there has been a lack of reliable quantitative data, particularly to assess network functionality. Advancing our understanding of volcanic ash vulnerability will enhance management strategies and improve the resilience of transportation networks. This thesis provides quantitative empirical results for vulnerability assessments of volcanic ash impacts on surface transportation, primarily through laboratory experimentation under controlled conditions that investigate three key impact types: 1) skid resistance on ash-covered roads and airfields, 2) road marking coverage by volcanic ash, and 3) visibility in airborne volcanic ash. Surface transportation functionality for thin (mm-cm) ash deposits forms the primary focus of this research due to limited existing knowledge, and as thin deposits often cover extensive areas and are readily re-suspended with potential repeated disruption. Various ash characteristics (e.g. thickness, particle size, soluble components, and ash wetness) are investigated in laboratory studies to assess the implications of different hazard intensity metrics on surface transportation functionality, with a focus on the transportation network in Auckland, New Zealand. Laboratory findings are used to identify thresholds for particular impacts, which are subsequently used to refine existing, and propose new, fragility functions for surface transportation and volcanic ash. Recommendations for clean-up and other mitigation measures to deal with volcanic ash on surface transportation networks are also suggested. Finally, new and previous impact findings are applied to a scenario focused on a hypothetical eruption in the Auckland Volcanic Field, New Zealand. Here, Level-of-Service metrics are developed to describe the disruption encountered by transportation end-users when networks are affected by volcanic ash, effectively providing a measure of transportation vulnerability. Overall, the findings of the thesis allow improvements to future volcanic impact and risk assessments and guide the development of resilient transportation infrastructure in volcanically active areas.

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  • Tax dispute systems design : international comparisons and the development of guidance from a New Zealand perspective.

    Jone, Melinda (2016)

    Doctoral thesis
    University of Canterbury Library

    Dispute systems design (DSD) refers to a deliberate effort to identify and improve the way an organisation addresses conflict by decisively and strategically arranging its dispute resolution processes. A number of principles have been put forward by various DSD practitioners for best practice in effective DSD. These principles emanate from the six fundamental DSD principles proposed by the seminal theorists Ury, Brett and Goldberg in Getting Disputes Resolved: Designing Systems to Cut the Costs of Conflict in 1988. To date, tax dispute resolution is an area that has not been extensively examined utilising DSD principles. However, with the recent trend of some tax authorities towards employing interests-based dispute resolution procedures, namely, various forms of alternative dispute resolution (ADR) processes, the application of DSD principles in the context of tax dispute resolution arguably warrants greater research. The purpose of this study is to develop the application of DSD principles in the particular context of tax dispute resolution. Utilising a comparative case study methodology, 14 DSD principles drawn from the literature have been used to evaluate the effectiveness of the design of the current tax dispute resolution processes of the jurisdictions of New Zealand (NZ), Australia, the United Kingdom (UK) and the United States (US). Through comparing the DSD evaluations conducted, this study has sought to develop a set of tax DSD principles to be adapted by tax administrations and used in either developing new or improving existing tax dispute resolution systems. Semi-structured interviews with 30 selected stakeholders in NZ have then been conducted in order to externally evaluate the tax DSD principles developed and also consider whether adaption of the principles is required in the context of the NZ tax dispute resolution procedures. The findings from the case studies indicate that the 14 DSD principles from the literature can generally be applied in the tax dispute resolution context without significant substantive modification. The interview findings suggest that the overarching design principle which must be borne in mind in the design of any tax dispute resolution system is that the system must be fair and perceived as fair. However, there is insufficient support from the interviews to justify any concrete changes being made to the tax DSD principles developed from the case studies. Thus, the interview findings are limited to the making of suggestions for certain modifications to the tax DSD principles potentially being made. Therefore, further research is necessary in order to confirm or refute the suggested changes. The interview findings further indicate that the tax DSD principles developed do not require adaptation specifically for NZ. Although, this may in part be due to the sample of participants interviewed being drawn only from NZ. Against the background of the overarching design principle of fairness, this study has a wide ranging applicability to tax administrations and their stakeholders in developing or improving their tax dispute resolution systems.

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  • Non-invasive monitoring of peripheral oxygen extraction and perfusion using photoplethysmography.

    Khan, Musabbir (2016)

    Doctoral thesis
    University of Canterbury Library

    In the intensive care unit (ICU), cardiovascular disease and sepsis are major drivers of morbidity, mortality, and cost. Microcirculatory dysfunction during sepsis and cardiac failure is known to significantly impair perfusion in major organs and peripheral tissues, resulting in poor patient outcome if not corrected early. Arterial oxygen saturation (SaO2), venous oxygen saturation (SvO2), and their difference, or oxygen extraction (O2E), in association with blood flow, are key parameters necessary to assess tissue perfusion. Although, SaO2 can be reliably estimated by non invasive optical technologies, such as pulse oximetry in terms of SpO2, there are no established, easy, or non-invasive methods to assess SvO2, and thus O2E. Therefore, real-time, low-cost, and non-invasive assessment of SvO2, O2E, and blood flow could significantly advance the diagnosis, management, and of care sepsis or cardiovascular disease in the ICU. This research focuses on the development of a novel pulse oximeter based concept to non invasively and more completely assess tissue perfusion in peripheral extremities, such as the finger. A transmittance pulse oximeter sensor was used as the basis of a device to estimate and monitor peripheral SvO2, O2E, and blood flow changes. Robustness of perfusion assessment methods at various digit skin temperatures was also investigated to improve accuracy and define the limits of sensor accuracy. A custom built pulse oximeter (PO) device and graphical user interface (GUI) were developed to access and acquire all photoplethysmograph (PPG) signals, including the raw PPG signals. A two stage digital filter system was implemented to extract useful signals from the PPG. Time and frequency domain methods, including peak-trough detection algorithms, were developed to analyse the PPG data and estimate parameters, such as SaO2 and heart rate. This system was thus used as the basis for developing SvO2 and blood flow monitoring methods, and also the investigation of temperature effects on PPG measurements. A study was conducted with healthy adult volunteers (n = 20) to investigate the effect of a range of digit skin temperatures on pulse oximeter performance using a transmittance pulse oximeter sensor. It was hypothesized that cold digits can significantly reduce PPG signal quality and the resulting accuracy of SpO2 measurements, due to the likely reduction in blood flow of the periphery at these temperatures. PPG data were recorded at cold, normal, and baseline skin temperatures, using the PO system as well as a commercial pulse oximeter for reference. Results show warm skin temperatures improved PPG signal quality up to 64.4% compared to baseline, and provided SpO2 estimation of 96.5[96.1 – 97] % in the expected range for healthy adults. At baseline conditions, the majority of subjects showed a good PPG signal and expected SpO2 estimate of 95.8[93.2 – 96.8] %. PPG signal quality degraded significantly up to 54.0% at cold conditions and SpO2 estimates of 88.5[87.1 – 92.8] % were unreliable when compared to baseline. The main outcome is a tri-linear model quantifying PPG signal quality as a function of temperature, suggesting warm skin temperature conditions (approximately 33°C) should be maintained for reliable transmittance pulse oximetry. In circulatory dysfunction, peripheral blood flow can be reduced, adding error to assessment of SvO2 and O2E using typical models and assumptions. Relative volumetric blood flow change assessments using the PO sensor were performed in a study using 7 human adult volunteers. The signal amplitude of the high frequency PPG component, which is related to the pulsatile arterial blood flow, was used as an indicator of blood flow change. A vascular Doppler ultrasound sensor was used as a reference measurement. Changes in blood flow conditions were induced by a series of vascular occlusion tests. Good correlation (R2 = 0.69) and trend agreement was obtained between median PPG amplitude and Doppler ultrasound velocity, particularly at normal and clinically important low flow conditions. Thus, PPG amplitude monitoring can be a potential surrogate or alternative to vascular Doppler ultrasound based blood velocity monitoring, and can provide continuous and reliable measurements, ensuring flow conditions can be included in assessing SvO2. A novel artificial pulse generation system (APG) was developed to cause low frequency and low pressure modulations of venous blood in the finger using a pneumatic digit cuff. The APG system used a feedback controlled pressure regulator and solenoid valve to inflate/deflate the pressure cuff. This system was designed to exploit the significant arterial-venous compliance difference and make the peripheral venous blood pulsatile, while having negligible impact on arterial blood flow. Ten healthy human adults were recruited for proof-of-concept testing of this device. Modulation ratio (R) values derived from the artificially modulated PPG signals were used to estimate venous oxygen saturation (SpvO2) using an empirical calibration equation developed for arterial blood. Conventional empirical calibration model estimated arterial and venous saturations of 96.95[96.1 – 97.4] % and 93.15[91.1 – 93.9] % agree with published literature values. Median O2E was 3.6%, with a statistically significant and expected difference (p = 0.002) between pairs of measurements in each subject. The APG system in association with the pulse oximeter device to assess SvO2 was then validated in a clinical study with healthy adult volunteers (n = 8). A range of physiologically realistic SvO2 values were induced using vascular occlusion tests. Gold standard, arterial and venous blood gas measurements were used as reference measurements. Modulation ratios related to arterial and venous systems were determined using a frequency domain analysis of the PPG signals. A strong, linear correlation (R2 = 0.95) was found between estimated venous modulation ratio and measured SvO2, providing a calibration curve relating measured modulation ratio of venous blood to oxygen saturation. Median venous and arterial oxygen saturation accuracies from paired measurements were 0.29% and 0.65%, respectively, showing good accuracy of the pulse oximeter system. Investigations also revealed the empirical calibration model used to estimate SpaO2 cannot be used estimate SpvO2 because of the difference in optical absorption caused by artificial perturbations. In particular, there is a significant difference in gradient between the SpvO2 estimation model (SpvO2 = 111 – 40.5*R) and the empirical SpaO2 estimation model of (SpaO2 = 110 – 25*R). The main outcome of this study presents a novel pulse oximeter based calibration model that can be used to assess peripheral SvO2, and thus O2E, using the device developed in this work. Overall, this thesis successfully develops and demonstrates a non-invasive, pulse oximeter based method to assess peripheral tissue perfusion in terms of SaO2, SvO2, O2E and volumetric blood flow changes. This novel sensor may potentially detect peripheral perfusion alterations in real-time during microvascular and/or overall circulatory dysfunction, such as in sepsis or cardiac failure. Future work will follow the application of the novel sensor in a comprehensive clinical study with a larger, more diverse, cohort.

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  • Current and future risks of radionuclide contamination to New Zealand’s food supply.

    Pearson, Andrew James (2016)

    Doctoral thesis
    University of Canterbury Library

    Identifying current and future food contamination risks is an important component of ensuring food security. Exposure to ionising radiation through dietary intake of radionuclides poses a potential source of food safety concern to New Zealand. Identifying and addressing current levels of exposure and future sources is necessary to ensure food security. An analytical survey of 40 common foods in the New Zealand diet was undertaken to establish current ranges for important radionuclides, including those of anthropogenic and natural origin. The derived activity concentrations for the thirteen radionuclides analysed were used to undertake dietary exposure modelling for ionising radiation doses to different age and gender groups of the New Zealand population. Exposure to naturally occurring radionuclides, in particular polonium-210, is the predominant source of the dose to the population, with seafood in the diet being the primary contributor to this dose. Anthropogenic radionuclides in contrast are present at only trace activity concentrations and present a low dietary exposure to ionising radiation dose. Exposure to caesium-137 and polonium-210 through seafood was identified as a source of near-term risk to increase the dietary burden to ionising radiation. Seafood samples from different species and harvested from different coastal regions were surveyed to determine the variability in activity concentrations. Activity concentrations of caesium-137 were low and showed little variation between regions. However, polonium-210 activities in shellfish were significantly higher than in other seafood types and displayed large variation between species. A dietary exposure model for seafood consumers identified the short-term risks from anthropogenic radionuclide exposure through seafood as a result of oceanic transport of caesium-137 are minimal in comparison to the dose of natural polonium 210 in these foods. The agricultural use of phosphate fertilisers containing radium-226 impurities was examined as a potential source for a long-term increase to the dietary ionising radiation burden. Analysis of phosphate ore and fertiliser samples identified a range of radium-226 activity concentrations. Radium-226 activity concentrations in agricultural soils, and also unexpectedly radium-228, appear to have increased considerably against values reported in the 1970s. Soil partitioning results showed that the radium-226 is predominantly bound in non-labile fractions and is unlikely to be available for crop uptake. Crop uptake in a number of common agricultural and horticultural crops was analysed to establish the dietary implications of an increase in soil radium-226 activity concentrations. The calculated concentration ratios correlate well with international default values for estimating crop uptake. Analysis of the concentration ratio in foliage at a site with a gradient of soil radium-226 established no increase in the crop activity concentration occurred. As a result, long-term loading of soil with radium-226 is unlikely to present a dietary risk. This conclusion was confirmed through conservative forecasting of the increased dose of radium-226 that might occur at current soil loading rates based on current fertiliser activity concentrations. The forecast model calculated that the increase to dietary ionising radiation burden is unlikely to reach thresholds requiring regulatory intervention for close to two millennia. Both short- and long-term radiological risks to New Zealand food security are considered minimal. New Zealand is currently well insulated from the risks of radiological exposure through the diet.

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