837 results for Doctoral, 2017

  • 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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  • 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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  • Late Quaternary vegetation and climate history reconstructed from palynology of marine cores off southwestern New Zealand

    Ryan, Matthew Thomas (2017)

    Doctoral thesis
    Victoria University of Wellington

    Little is known about how mid-latitude Southern Hemisphere terrestrial vegetation responded during glacial terminations and the warmer phases of the Late Quaternary, especially beyond the last glacial cycle where records are commonly fragmentary and poorly-dated. The timing, magnitude and sequence of environmental changes are investigated here for terminations (T) I, II and V and their subsequent warm interglacials of MIS 1, 5e and 11 by direct correlation of terrestrial palynomorphs (pollen and spores) and marine climate indicators in marine piston cores MD06-2990/2991 recovered from the East Tasman Sea, west of South Island, New Zealand. The climate there is strongly influenced by the prevailing mid-latitude westerly wind belt that generates significant amounts of orographic rainfall and the proximity of the ocean which moderates temperature variability. Chronological constraint for the cores is provided by δ¹⁸O stratigraphy, radiocarbon chronology and the identification of two widespread silicic tephra horizons (25.6 ka Kawakawa/Oruanui Tephra (KOT); ~345 ka Rangitawa Tephra (RtT)) sourced from the central North Island. Similar vegetation changes over the last two glacial cycles at MD06-2991 and in the adjacent nearby on land record of vegetation-climate change from Okarito Bog permit transfer of the well resolved Marine Isotope Stage (MIS) chronology to Okarito for the pre radiocarbon dated interval (~139-28 ka). Placing both sequences on a common age scale nonetheless assumes there is minimal lag between pollen production and final deposition on the seafloor. However, the timing of Late Pleistocene palynomorph events and KOT between independently dated marine and terrestrial sedimentary sequences are found in this study to be indistinguishable, which supports the direct transfer of terrestrially derived ages to the marine realm and vice versa. Vegetation change in southwestern New Zealand is of similar structure during T-I and T-II, despite different amplitudes of forcing (i.e., insolation rise, CO₂ concentrations). In a climate amelioration scenario, shrubland-grassland gave rise to dominantly podocarp-broadleaf forest taxa, with accompanying rises in mean annual air temperature (MAAT) estimated from Okarito pollen typically synchronous with nearby ocean temperatures. The T-II amelioration commenced after ~139 ka in response to increasing boreal summer insolation intensity, with prominent ocean-atmosphere warming over the period from ~133-130 ka. In contrast, northern mid-high latitude paleoclimate records display cooling over Heinrich Stadial 11 (~135-130 ka), and are prominently warm from ~130-128 ka, while southwestern New Zealand and the adjacent ocean displays cooling. Such millennial-scale climate asynchrony between the hemispheres is most likely a result of a systematic, but non-linear re-organisation of the ocean-atmosphere circulation system in response to orbital forcing. The subsequent MIS 5e climatic optimum in Westland was between ~128-123 ka, with maximum temperatures reconstructed in the ocean and atmosphere of 2.5°C and 1.5°C higher than present. Similarities revealed between land and sea pollen records in southwestern New Zealand over the last ~160 ka offer confidence for assessing vegetation and climate for older intervals, including T-V/MIS 11, for which no adjacent terrestrial equivalents currently exist. Vegetation change over T-V is similar to T-II and T-I, with southern warming antiphased with northern mid-high latitude cooling. Tall trees and the thermophilous shrub Ascarina lucida define interglacial conditions in the study region between ~428-396 ka. East Tasman Sea surface temperatures rose in two phases; 435-426 ka (MIS 12a-MIS 11e) and 417-407 ka (MIS 11c climatic optimum), reaching at least ~1.5-2°C warmer than present over the latter. Similarly, Ascarina lucida dominance over MIS 11c is akin to that displayed during the early Holocene climatic optimum (11.5-9 ka) in west-central North Island, where MAAT average ~3°C higher today. This contrasts markedly with the dominance of the tall tree conifer Dacrydium cupressinum for the Holocene (MIS 1) and last interglacial (MIS 5e) in southwestern New Zealand. Biogeographic barriers are proposed to have inhibited the migration of species from more northerly latitudes better adapted to warmer climatic conditions over MIS 5e and MIS 11.

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  • Orisa-Shakespeare: A study of Shakespeare Adaptations Inspired by the Yoruba Tradition

    Balogun, Olalekan Is’haq (2017)

    Doctoral thesis
    Victoria University of Wellington

    This thesis combines creative practice with critical analysis to intervene in the field of post-colonial Shakespeare where, for over a generation, the process of adaptation has been presented as one of the main strategies by which Shakespeare’s ambiguous legacy in successor cultures can be both confronted and manipulated. Scholars often use the term “writing back” to designate a set of adaptations which challenge the cultural capital that Shakespeare privileges. By linking Yoruba spirituality in its political and cultural terms to the wider field of the relation between Africa, African writers and theatre makers and Shakespeare, the thesis proposes a new sub-field or genre of adaptations, “Orisa-Shakespeare,” rooted in Yoruba traditions. The thesis argues that, written in Nigeria and the Yoruba global diaspora, this set of adaptations are not necessarily challenging the Shakespeare canon but addressing their own societies, thus “writing forward.” The thesis examines the cultural and political significance of this bourgeoning body of adaptations of Shakespeare through the lens of Yoruba epistemology and its aesthetic principles. The thesis is broadly divided into two parts: an exegesis of selected adaptations of Shakespeare as case studies of post-colonial works that reflect and integrate Yoruba creative and performative idioms and translate them into dramaturgy; and an original play, Emi Caesar! in which core elements of Shakespeare’s Julius Caesar are transplanted into the complex, violent world of Yoruba politics of the mid-19th century, as a parable for contemporary Nigeria politics where factionalism (specifically tribal/ethnic bigotry) works against the integrity and security of the society. In the context that the thesis proposes, the present has constant recourse to the past, especially the ancestors, and engages in rituals which create ongoing, living links between human beings and the realm of the Yoruba Gods (Orisa).The outcomes are the documentation of a uniquely Yoruba theory of literary creativity, a new play based on Julius Caesar, and an original contribution to the broad field of postcolonial (Shakespeare) adaptations scholarship.

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  • Early to middle Eocene calcareous nannofossils of the SW Pacific: Paleobiogeography and paleoclimate

    Shepherd, Claire Louise (2017)

    Doctoral thesis
    Victoria University of Wellington

    Earth’s climate underwent a long-term warming trend from the late Paleocene to early Eocene (~58–51 Ma), with global temperature reaching a sustained maximum during the Early Eocene Climatic Optimum (EECO; 53–50 Ma). Geochemical proxies indicate tropical or warm subtropical sea-surface temperature (SST) conditions in middle and high latitudes in the early Eocene, implying a very low latitudinal temperature gradient. This study investigates whether calcareous nannofossil assemblages in the southwest (SW) Pacific provide evidence of these conditions at middle latitudes in the early to middle Eocene, particularly during the EECO. Specifically, this study documents the biogeographic changes of warm- and cold-water nannofossil species along a paleolatitudinal transect through the EECO to track changes in water masses/ocean circulation at that time. Early to middle Eocene calcareous nannofossil assemblages were examined from four sites along a latitudinal transect in the SW Pacific, extending from Lord Howe Rise in the north to Campbell Plateau in the south and spanning a paleolatitude of ~46–54°S. All of the sections studied in this project span nannofossil zones NP10–16 (Martini, 1971). The data indicate up to three regional unconformities through the sections: at mid-Waipara, Deep Sea Drilling Project (DSDP) Site 207 and 277, part or all of Zone NP10 (lower Waipawan) is missing; at Sites 207 and 277 a possible hiatus occurs within NP12 (upper Waipawan–lower Mangaorapan); and at all sites part or all of Zone NP15 (lower Bortonian) is missing. Results of this study indicate that nannofossil assemblages in the SW Pacific are more similar to floras at temperate to polar sites rather than those at tropical/subtropical sites. However, variations in the relative abundance of key species in the SW Pacific are broadly consistent with the trends seen in the geochemical proxy records: an increase in warm-water taxa coincided with the EECO, corroborating geochemical evidence for a temperature maximum in the SW Pacific during this interval. The increase in the abundance and diversity of warm-water taxa and decrease in the abundance of cool-water taxa through the EECO supports previous suggestions that a warm-water mass (northward of the proto-Tasman Front) extended to ~55°S paleolatitude during this interval in response to enhanced poleward heat transport and intensification of the proto-East Australian Current. At the southernmost site, DSDP Site 277, a relatively short-lived influx of warm-water taxa at ~51 Ma suggests that warm waters expanded south at this time. However, greater diversity and abundance of warm-water taxa throughout the EECO at DSDP Site 207, suggests that the proto-East Australian Current exerted greater influence at this latitude for a longer duration than at Site 277. An increase in the abundance of cool-water taxa and decrease in diversity and abundance of warm-water taxa at all sites is recorded following the termination of the EECO. This corresponds with the contraction of the proto-Tasman Front due to weakened proto-East Australian Current flow and associated amplification of the proto-Ross Gyre. Previous estimates of SSTs from geochemical proxies in the SW Pacific during the EECO indicate that there was virtually no latitudinal temperature gradient and temperatures were tropical to subtropical (>20°C). However, nannofossil data from this study indicate warm temperate conditions (~15–20°C) during the EECO, suggesting that a reduced latitudinal gradient was maintained through this interval, which is in agreement with climate models.

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  • Thresholds, Text Coverage, Vocabulary Size, and Reading Comprehension in Applied Linguistics

    Larson, Myq (2017)

    Doctoral thesis
    Victoria University of Wellington

    The inextricable link between vocabulary knowledge and reading comprehension is incontrovertible. However, questions remain regarding the nature of the interaction. One question which remains unresolved is whether there is an optimum text coverage, or ratio of known to unknown words in a text, such that any deleterious effects of the unknown words on reading comprehension are minimised. A related question is what vocabulary size would a reader need to have in order to achieve the optimum text coverage for a given text or class of texts. This thesis addresses these questions in three ways. First, a replication and expansion of a key study (Hu & Nation, 2000)1 was performed. In that study, 98% text coverage was found to be optimal for adequate reading comprehension of short fiction texts when reading for pleasure. To replicate that study, equivalent measures of reading comprehension were collected from a more homogeneous group of participants at a university in northern Thailand (n = 138), under stricter conditions and random assignment to one of three text coverage conditions, to verify the generalisability of the results. The original study was also expanded by measuring reader characteristics thought to contribute to reading comprehension, such as vocabulary size, l1 and l2 literacy, and reading attitudes, in an effort to improve the explainable reading comprehension variance. In order to more accurately calculate the text coverage a reader experiences for a particular text, both the vocabulary profile of the text and the vocabulary size of the reader must be known as precisely as possible. Therefore, to contribute to the question of vocabulary size, changes such as measuring item completion time and varying the order of item presentation were made to the VST (P. Nation & Beglar, 2007) to improve its sensitivity and accuracy. This may ultimately lead to increased precision when using text coverage to predict reading comprehension. Finally, l2 English vocabulary size norms were established to supplement the diagnostic usefulness of the VST. Data were collected through an online version of the VST created for this thesis from primarily self-selected participants (n 1:31 105) located in countries (n 100) around the world representing several l1 and age groups. Analysis of the data collected for this thesis suggest that text coverage explains much less reading comprehension variance than previously reported while vocabulary size may be a more powerful predictor. An internal replication of Hu and Nation (2000) found errors in the calculation of optimum text coverage and in the reported size of the effect on reading comprehension. A critical review of the theoretical foundations of the text coverage model of reading comprehension found serious flaws in construct operationalisation and research design. Due to these flaws, most research which has purported to measure the effect of text coverage on reading comprehension actually measured the effect of an intervening variable: readers’ vocabulary size. Vocabulary size norms derived from data collected through an online version of the VST appear to be reliable and representative. Varying item presentation order appears to increase test sensitivity. Despite a moderate effect for l1 English users, item completion time does not seem to account for any variance in vocabulary size scores for l2 English learners. Based on the finding that vocabulary size may explain both reading comprehension and text coverage, the putative power of text coverage to predict reading comprehension is challenged. However, an alternative measure which may offer greater power to predict reading comprehension, the VST, has been modified and made available online. This version of the VST may provide greater sensitivity and ease of use than the offline, paper-based version.

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  • A Quarter Acre Pavlova Paradise Lost? The Role of Preferences and Planning in Achieving Urban Sustainability in Wellington, New Zealand

    Dodge, Nadine (2017)

    Doctoral thesis
    Victoria University of Wellington

    This thesis investigates the scope for compact development to accommodate population growth in Wellington, New Zealand. The topic is particularly significant for New Zealand as the great majority of the population lives in urban areas, historical development has been dominated by low density urban form, and transport and urban form are two of the main domains in which the country can reduce its carbon emissions. The influence of urban planning and residents’ preferences on achieving sustainable outcomes is investigated. Historical and current planning rules and transport policies in the City are analysed to determine their influence on the provision of compact development. Wellington’s transport policy shows a pattern of path dependency: historical decisions to favour car oriented investment have driven subsequent transport investments and influenced the ease of using different transport modes. Planning policies show a similar pattern of path dependency: planning rules enacted in the 1960s endure in present planning despite being packaged with different justifications and regulatory regime. Current planning rules severely restrict infill development in most existing neighbourhoods, which reduces the availability of housing in accessible medium density neighbourhoods and likely increases the cost of this type of housing. A stated choice survey was conducted of 454 residents of Wellington City to investigate the extent to which there is an unmet demand for compact development and alternatives to car travel. The survey held presentation mode constant across two completion modes (internet and door to door with tablet completion), allowing the impacts of recruitment and completion mode to be examined. Survey recruitment mode appeared to influence both response rates and the representativeness of the survey, while completion mode appeared to have little or no impact on survey responses. Using the stated choice survey results, a latent class model was developed to examine the preferences of residents and the trade-offs they are willing to make when choosing where to live. This type of model allows for the identification of preference groups as a means of understanding the diversity of preferences across the population. The study found that there is an unmet demand for medium density, accessible housing, but that affordability is a barrier for households to choose this type of housing. There was also an unmet demand for walking and cycling, with more residents currently driving than would prefer to use this mode, and more residents preferring to walk and cycle to work than currently use these modes. The ability to use a desired travel mode appears to be related to the neighbourhood in which a person lives, with residents of medium and high density neighbourhoods being more likely to use their preferred travel mode. This study also modelled future development trajectories for Wellington based on demand for housing, neighbourhood and transport attributes. This preference based growth model was contrasted with the City’s plan for development over the next 30 years. Comparing the two scenarios, the planning based trajectory performed better than the demand based scenario in terms of both carbon emissions and achieving compact development.

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  • The Environmental Regulation of Marine Carbon Capture and Storage in New Zealand: Principles, Barriers and Gaps

    Severinsen, Gregory (2017)

    Doctoral thesis
    Victoria University of Wellington

    This thesis concerns the regulation of a technology called carbon capture and storage (CCS). The technology is one way to mitigate anthropogenic climate change, by capturing carbon dioxide (CO2) emissions at point sources (such as power or industrial plants) and injecting them into deep underground geological formations. Specifically, the thesis looks at the framework of public environmental law that is needed for CCS in New Zealand where injection occurs offshore in its coastal marine area and exclusive economic zone. The thesis concludes that, when tested against existing principles in New Zealand's environmental law and the requirements of international law, current provisions in domestic law contain both significant barriers and gaps. These barriers must be removed and gaps must be filled. The thesis identifies three broad features of New Zealand's law that give rise to a range of barriers and that need to be addressed. First, there is substantial uncertainty as to how existing provisions would apply to CCS. Greater certainty is needed. Secondly, the classification of CCS as a form of marine dumping presents a significant barrier. The technology needs to be classified differently, and more positively. Thirdly, the law contains a general prohibition on considering the effects of activities on climate change. This may prevent CCS being deployed in practice, and needs to be reconsidered. New Zealand's existing law also contains three potential gaps, which must be filled. First, there is a dearth of CCS-specific regulatory and policy provisions within existing regimes such as the Resource Management Act 1991. This means operators and regulators would be operating in a regulatory and policy vacuum. Decisions may be inconsistent, fail to impose appropriate environmental standards, or fail to give appropriate weight to relevant considerations. Secondly, there are limitations in the ability of existing regimes to regulate the positive effects of activities – such as climate change mitigation - to ensure that they are actually achieved. Thirdly, existing law does not facilitate the kind of targeted and comparative decision-making process needed for CCS. This means that it does not provide an effective process for resolving tensions between competing resource interests in the sub-seabed.

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  • Negotiating multiple identities in educational contexts: Stories of Tamil Heritage Language Users as Multilingual Malaysians

    Sithraputhran, Thilegawathy (2017)

    Doctoral thesis
    Victoria University of Wellington

    Malaysia is a multilingual and multicultural society comprising of ethnic Malays (dominant group) followed by ethnic Chinese, Indians and other indigenous groups. The national language is Malay and English is the second language. Heritage languages such as Mandarin and Tamil are used as the language of instruction in some primary schools. This study explores how a group of Tamil Heritage Language Users from Tamil primary schools (THLU-Ts) at a private university recounted maneuvering through their multilingual world during their early lives at Tamil primary school, at state secondary school (Malay) and then at a private university (English). Nine first year undergraduate participants were selected from a private university in Malaysia where English is the medium of instruction. They were selected as THLU-Ts based on two criteria. Firstly, they were ethnic Tamils and secondly, they had completed six years of primary education at Tamil primary school. I used photovoice interviews to construct their narratives. The participants, prompted by photographs they brought as artefacts, described their language experiences in a multilingual setting. The participants’ voices were storied into narratives based on three narrative inquiry strategies of broadening, burrowing and restorying. Two in-depth interviews were conducted over a six month period and these were video-taped and transcribed. The interview transcript from each first interview contributed to a narrative summary or story. This was a general description of the participant and events (broadening stage). The second interview was held towards the end of the semester. During the second interview, participants were asked to reflect on their narrative summaries (which had been distributed earlier) and comment on them. I sought data to reexamine the existing data (burrowing stage) before rewriting a complete and coherent story (restorying) for each participant. This story was also individually reviewed by each participant. Data analysis was an iterative process that included storying and coding. I identified three broad themes and then examined them in the light of relevant literature. This analysis allowed me to understand how the THLU-Ts shaped their identities during social interactions with different linguistic communities in Malaysia, including THLU-Ms (ethnic Tamils from national primary schools) and non-Tamils (Malays and Chinese). Initially, THLU-Ts faced challenges as they transitioned to secondary school coming from a Tamil- medium primary school. At secondary school, they had to adjust to a Malay linguistic environment for the first time. As their proficiency in Malay grew, they felt they were accepted as authentic members of the academic community. When they entered the English-medium university, there was pressure to develop proficiency in English. They repositioned themselves once again and made deliberate language choices during social interaction with other linguistic communities. When the findings were viewed through Blommaert’s sociolinguistic scales, it was apparent that participants scaled languages depending on the value assigned to each one (Malay, English and Tamil). This reflected the way language was used in society. As powerful multilinguals who invested in a multilingual repertoire, participants displayed linguistic accommodation. These findings suggest a need for educators and policy makers to reassess the role and importance of HL education. Currently, the Malaysian education policy is silent on its commitment to HL education in Malaysia. Yet, this research supports the One Malaysia concept which stresses unity in diversity and encourages educational policies to take a pro-multilingual stance.

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  • You are not worth the risk: The ethics of statistical discrimination in organisational selection of applicants

    Scholes, Vanessa (2017)

    Doctoral thesis
    Victoria University of Wellington

    Your job application is rejected unseen because you ticked a box admitting you smoke. The employer screened out applicants who ticked the 'smoker' box, because she had read empirical studies that suggest smokers, as a group, are a higher productivity risk than non-smokers. What distinctive ethical concerns inhere in the organisational practice of discriminating against applicants on the basis of group risk statistics? I argue that risk-focussed statistical discrimination is morally undesirable due to the lack of respect for applicants as unique autonomous agents. However, I argue further that the decision-making context affects the morality of this discrimination. Other things being equal, the morality of statistical discrimination varies depending on the purpose of the organisation, the level of detail in the discrimination, and whether the discrimination is transparent to applicants and includes some benefit for applicants. Because organisations may have good reason to use risk-focussed statistical discrimination when assessing applicants, I present some recommendations for decision-makers to mitigate the lack of respect for applicants as individual agents. Organisational decision-makers can focus on the extent to which the statistical data they use comprise i) factors that feature efforts and achievements of the applicant; ii) dynamic rather than static factors; and iii) data drawn from the applicant’s own history and actions over time.

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  • Design foundations: Towards a model of style grammar in creative drawing

    Sweo, Jennie (2017)

    Doctoral thesis
    Victoria University of Wellington

    A style grammar is a principled rule set that governs the organization of very complex ideas. It allows for the examination of underlying structures which are often times obscured. Style grammars have been developed for many fields such as writing, fashion and architecture but to date there is no style grammar for creative drawing. The research identifies the necessary visual features and core traits associated with each feature towards developing such a model for creative drawings. Then operational measures are defined using the computer to extract and measure the core traits of those features towards developing a model of style grammar in drawing. These visual features include line, tone, and depth. Core traits include line length, line width, line expressiveness, local tone, global tone, texture, pattern, outline, shape, and position. A multidimensional scaling (MDS) using input from 27 subjects, 10 art experts and 17 novices, supported the overall list of visual features and added the dimension of smudge to the list. A second MDS sort discusses issues with images and large art categorical sorts from the standpoint of both human perception and machine measures that were obtained using feature extraction. It was concluded from the results of the second MDS that large art categories were too broad to be useful in evaluating measures to develop the model. Further analysis was run using only drawings from three artists, two impressionists to compare similarity and one expressionist for dissimilarity to determine if the machine measures of the core traits of the visual features were able to differentiate smaller groupings of consistent drawing styles. Using the computer allowed for systematic and objective procedures to be used to obtain measures. The multinomial logistic regression showed high significance for all the traits except marginal significance for line length and no significance for depth. Binomial logistic regressions run on each pair of artists showed high significance for all the traits except depth. The combined positive results of the first MDS card sort and the binomial and multinomial regression analysis provide proof of concept and offer strong support towards the development of a model of style grammar for creative drawings. Implications for teaching drawing using the identified visual features and core traits are offered. The outcomes and analysis provided in this research currently support a general practice rule in design reuse and intelligent borrowing that suggests first smudge, then depth, then tone, and then line quality are the most significant elements to use for style comparison. Discussions for future research including improved measures and other types of perception testing are provided towards further development of the model.

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  • Narrating connections and boundaries : constructing relatedness in lesbian known donor familial configurations.

    Surtees, Nicola Jane (2017)

    Doctoral thesis
    University of Canterbury Library

    In a time of unprecedented possibilities for intimate life, lesbian known donor reproduction is an emerging form of kinship practice. While experienced as unique to the biographies of particular lesbian couples, known donors and their partners, practices of relatedness occur against the background of neoliberal discourses, processes of normalisation and legislative frameworks that are increasingly responsive to the rights claims of lesbian parents. This thesis investigates this phenomenon in contemporary New Zealand. Examining the meanings attached to cultural constructs such as ‘kinship’, ‘family’, ‘parenthood’, ‘motherhood’ and ‘fatherhood’, the thesis illustrates how familial boundaries and sets of relations are narratively constructed. The research draws on interviews with 60 women and men across 21 lesbian known donor familial configurations at different stages of forming family through known donor insemination, focusing in depth on nine core family narratives. Participants included lesbian parents and parents to be, gay and heterosexual known donors, and partners of donors. The thesis argues that participants are innovative in conformity and through constraint. Although the participants live amid the same dominant heteronormative public narratives, they are differently normative. They pursue different familial scenarios, which creates different possibilities for lesbian couple and parenting selves and identities relative to donors and their partners. The picture emerging suggests donors and partners remain supplementary to lesbian couples. How their status is expressed is a central theme of the thesis that demonstrates the power of neoliberal agendas of personal responsibility, freedom, agency and choice. Tensions between a sense of empowerment and constraint in family-building activities are closely linked to these agendas. Contributing to debates about the operation of homonormativity in a neoliberal context, this thesis explores the discursive power of heteronormative family models and the implications of this for innovation in the intimate lives of same-sex and heterosexual subjects.

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  • Numerical modelling of groundwater - surface water interactions with the Double-Averaged Navier-Stokes Equations.

    Dark, A. L. (2017)

    Doctoral thesis
    University of Canterbury Library

    The ability to model groundwater and surface water flows as two interacting components of a single resource is highly important for robust catchment management. Existing methods for spatially-distributed numerical modelling of flow in connected river-aquifer systems treat rivers and aquifers as separate sub-domains, with different governing equations for the flow in each. Mass-fluxes exchanged between the sub-domains are modelled using one of several coupling methods, which do not accurately represent the physics of the flow across the interface between the surface and subsurface flows. This can be problematic for model stability and mass conservation. This thesis investigates the feasibility of modelling interacting surface water and groundwater flows in a single domain, using a single system of equations. It is shown that the governing equations in existing numerical models for river and aquifer flow can be derived from the Navier-Stokes Equations. A time- and space-averaged form of Navier-Stokes Equations, the Double-Averaged Navier-Stokes (DANS) Equations, can be used to model both groundwater and surface water flows. The volume- averaging process allows the porous medium to be represented as a continuum. A novel two-dimensional numerical model is developed from the DANS Equations to simulate flows in connected groundwater and surface water systems. The DANS equations are solved using the finite-volume method. The model simulates two-dimensional flow in a vertical slice. This allows the horizontal and vertical velocity components and pressure to be modelled over the depth of a stream and the underlying aquifer or hyporheic zone. The model does not require the location of the interface between surface and subsurface flows to be specified explicitly: this is determined by the spatial distribution of hydraulic properties (permeability and porosity). The numerical model handles the transition between laminar and turbulent flows using an adaptive damping approach to modify the terms in a single-equation turbulence model, based on a locally-defined porous Reynolds number, Rep. This approach removes the need to specify a priori whether flows in any part of the domain are laminar or turbu lent. Turbulent porous media flows can be simulated. The model is verified for porous-media and clear-fluid flows separately, before being used to simulate coupled groundwater - surface water flow scenarios. For porous-media flows with low Rep the numerical model results agree exactly with Darcy’s Law. The value of Rep at which the model results begin to deviate from Darcy’s Law is consistent with published values. For turbulent clear-fluid flows the time-averaged velocity and turbu lent kinetic energy (TKE) results from the numerical model are ver ified against a RANS model and published data. A good match is achieved for both velocity and TKE. Energy grade-line slopes for free-surface flows simulated in the numerical model are a reasonably good match to equivalent results to the one-dimensional hydraulic model HEC-RAS. Idealised river-aquifer interaction experiments are conducted in a lab- oratory flume to provide verification data for the numerical model. An innovative combination of optical flow measurement and refractive- index-matched transparent soil is used to measure two-dimensional velocities and turbulent statistics in laboratory flow scenarios that simulate flow in both losing and gaining streams, and the underlying connected porous layer. The “gaining stream” laboratory scenario is replicated using the numerical model. The model simulates the key features of the mean flow well. Turbulent statistics deviate substantially from the laboratory results where vertical velocities across the surface-subsurface interface are high, but are a better match elsewhere. The “losing stream” laboratory results are unable to be reproduced with the numerical model. Results for a similar scenario with lower outflow velocities are presented. These results are qualitatively consistent with the laboratory results. The numerical model is expected to perform better in simulations of field-like conditions that involve less extreme gradients than the laboratory scenarios.

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  • Gender, class and modernity : reproductive agency in urban India.

    Kohli, Ambika (2017)

    Doctoral thesis
    University of Canterbury Library

    The decreasing female child sex ratio in contemporary India is often linked to the small family norm. However, the decline of sex ratio has raised interesting questions regarding women’s involvement in decision making in the context of female-foeticide and managing family size. Are women victims or actors while making their reproductive choices? What are their reproductive interests, and how do they achieve them? This study investigates how urban-middle class women from Delhi and Haryana make reproductive decisions in regards to family formation in modern urban neoliberal society. Motherhood, abortions, and gender relations are discussed with reference to the main themes of son-preference, increasing social status of daughters, family planning, family building strategies, reproductive health and well-being. Further, because of the prevalence of son-preference it is crucial to understand what kind of status daughters are accorded in contemporary urban Indian society. This study addresses this by looking at participants’ differing perceptions and expectations for their daughters and sons, and in particular how daughters are treated. The status of daughters is documented through an examination of current forms of gender discrimination against them, and also the different kinds of opportunities that they are provided by their parents. These issues are explored through a qualitative study of the reproductive decision making of 45 educated married urban middle-class mothers from Delhi and Yaumuna Nagar (region of Haryana), India. Snowballing was used to recruit participants, and the fieldwork was carried out during two visits to India. I chose Delhi and Haryana because both of these regions have collective and patriarchal family structures. For instance, in these regions joint families are quite common among the middle-class and fathers or a male family member are often the head of the family. Furthermore, Delhi and Haryana have a low female child sex ratio, as recorded in the 2011 census, but have shown slight improvement in comparison to 2001 figures. Therefore, this study will provide insights into how women practice their reproductive agency in highly collective and patriarchal settings of their affinal families. These families are in the process of rapid socio-cultural changes, including change in gender roles and opportunities for daughters. I will examine women’s decision making process, including practices of negotiating and resistance strategies they develop. xvi I will then discuss how women engage with different forms of modern, spiritual and traditional technologies in order to maintain their reproductive health and well-being, and how they attempt to give birth to a son while maintaining the norm of small family size. This will suggest that society and technology are mutually constitutive. Finally, I will explore how social transformation has influenced the gender relationships which are discussed in relation to daughters’ improving status and also the different forms of discrimination currently used against them. However, throughout the research the patriarchal nature of urban neoliberal Indian society and the idea that a man is needed to support a woman and for her protection has been highlighted.

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  • Young People’s Experience of Post-Separation Fathering Where the Father has been Violent to the Mother

    Nelson, Pamela (2017)

    Doctoral thesis
    Victoria University of Wellington

    My intention in undertaking this research was to examine young people’s experiences of living with their father following parental separation where their father has been violent to their mother. To date there is little knowledge of children’s post-separation experiences of fathering or of the parenting abilities of partner abusive men. This study takes a feminist approach and is informed by scholarship on family issues, childhood studies and the sociology of the child. The study was guided by hermeneutic phenomenology and thematic analysis was used to analyse the data. Twenty young people aged 18 to 26 took part in the study and face to face interviews were carried out over a one year period. The findings revealed that some fathers were overly punitive in their parenting style with a number of fathers continuing to be physically and/or emotionally abusive to their children. Authoritarian or permissive parenting practices were also identified and a number of fathers were shown to be neglectful, making little effort to bond with their children or provide quality care. In cases where fathers were unable to accept the break-up and move on this was also shown to have an adverse effect on their ability to parent effectively including an inability to co-operate with children’s mothers. In contrast, the majority of mothers were shown to be central to children’s lives undertaking most of the caring responsibilities. Mothers also recognised children’s changing needs as they grew older, encouraged autonomy, and contributed to children’s social development and maturity by trusting their judgement. However, this was not necessarily a protective factor against difficulties that participants have experienced as young adults. A time-share or full-time arrangement was revealed as being the most problematic for children although weekend contact could also pose a risk where pre-separation violence towards children had been severe. The study concluded that a safe outcome for children will require a shift away from a father’s right to contact, emphasising instead children’s right to a life free from abuse.

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  • Carbon and root system architecture : key regulators in nitrogen uptake in Lolium perenne L. and Brassica napus L.

    Guo, Qianqian (2017)

    Doctoral thesis
    University of Canterbury Library

    Nitrogen (N) is an essential macronutrient that limits plant yield and productivity. In order to increase crop yield, considerable amounts of nitrogenous fertilizers are applied to agriculture systems each year. However, about 25-70% of the applied fertilizer in ecosystem has been leached and released to the environment, in the form of NO, N₂O and NH₃, aggravating environmental pollution. Therefore, increasing nitrogen use efficiency in agriculture systems is essential to maintain the food production while alleviating the deleterious environmental effects of applied N. The mechanisms linking C/N balance to N uptake and assimilation are central to plant responses to changing soil nutrient levels. Defoliation and subsequent regrowth of pasture grasses both impact C partitioning, thereby creating a significant point of interaction with soil N availability. Using defoliation as an experimental treatment, the dynamic relationships between plant carbohydrate status and NO₃⁻-responsive uptake systems, transporter gene expression and N assimilation were investigated in Lolium perenne. High- and low-affinity NO₃⁻ uptake were reduced in an N-dependent manner in response to a rapid and large shift in carbohydrate remobilization triggered by defoliation. This reduction in NO₃⁻ uptake was rescued by an exogenous 1% glucose supplement, confirming the carbohydrate-dependence of NO₃⁻ uptake. The regulation of NO₃⁻ uptake in response to the perturbation of plant C/N was associated with changes in expression of the nitrate high-affinity transporter LpNRT2.1b. Furthermore, NO₃⁻ assimilation appears to be regulated by the C/N balance, implying a mechanism that signals the availability of C metabolites for NO₃⁻ uptake and assimilation at the whole-plant level. This study also shows that cytokinins are involved in the regulation of nitrogen acquisition and assimilation in response to the changing C/N ratio. Root architecture is also a crucial component that impacts the capacity of plants to access nutrients and water. By using the recently developed package RootNav, comprehensive morphological changes in root system architecture in response to different N sources were investigated in Brassica napus. In order to avoid a light-induced morphological and physiological responses affecting whole plant growth, an existing solid agar vertical-plate system was modified so that to allow roots to be shielded from light without sucrose addition and the emerging shoot to be grown without direct contact with the medium, thereby mimicking more closely the environmental conditions in nature. The results of 10-days-old B. napus seedlings showed that total root length, LR density and root exploration area decreased with increasing external NO₃⁻ concentrations from 0.5 mM to 10 mM. The application of 0.5 mM NO₃⁻ induced more branching in the root system relative to the treatments with higher N concentrations (5 mM and 10 mM). The proportion of biomass allocation occupied by roots was greater in the low NO₃⁻ treatment relative to the high NO₃⁻ treatments, reflecting the fact that plants invested more resources in their roots when nutrient uptake from the environment was limited. In treatments of increasing NH₄⁺ concentration from 0.5 mM to 10 mM, primary root length, total root length, LR branching zone, LR density and root exploration area were reduced. These results indicated that NH₄⁺ toxicity usually leads to a stunted root system in B. napus, whereas a low concentration of NH₄⁺ is an optimal nitrogen resource for plant growth. Increasing L-glutamate concentration from 0.01 mM to 0.1 mM suppressed primary root length, whilst the LR branching zone did not change in the different L-glutamate treatments, suggesting that L-glutamate even at micromolar level could arrest primary root growth and LR branching in B. napus. By using in situ ¹⁵N isotope labelling, morphological and molecular phenotypes generated pharmacologically were employed to investigate whether the impacts of contrasting root traits are of functional interest in relation to N acquisition. Brassica napus L. were grown in solid medium containing 1 mM KNO3 and treated with cytokinin, 6-benzylaminopurine, the cytokinin antagonist (PI-55), or both in combination. The contrasting root traits induced by PI-55 and 6-benzylaminopurine were strongly related to ¹⁵N uptake rate. Large root proliferation led to greater ¹⁵N cumulative uptake rather than greater ¹⁵N uptake efficiency per unit root length. This relationship was associated with changes in C and N resource distribution between the shoot and root, and in expression of BnNRT2.1. The root/shoot biomass ratio was positively correlated with ¹⁵N cumulative uptake, suggesting the functional utility of root investment for nutrient acquisition. These results demonstrate that root proliferation in response to external N is a behaviour which integrates local N availability and systemic N status in the plant. In conclusion, using two major economic forage species, L. perenne and B. napus, this thesis illuminates the impacts of carbon and root system architecture on N uptake. This work contributes to our understanding of the mechanisms regulating N uptake and will help further in efforts to improve nitrogen use efficiency.

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  • Integrated response as a process for enhancing the incident command system

    Fakuade, Dolapo (2017)

    Doctoral thesis
    University of Canterbury Library

    The devastating societal impacts of disruptive events have emphasised the need for more effective and unified emergency response arrangements. While policies that guide strategies, measures or approaches are not lacking in the emergency sector, they tend to be inadequate for response and relatively ineffective during response to large-scale or unprecedented events. This research critically examines theoretical bases and practice systems for emergency response, in order to identify useful community functions which can be integrated with emergency management response. The aim is to develop an integrated response framework that can be adopted to improve response to disruptive events. The data for this research were gathered through case study analyses of communities in Christchurch, which provided context for and helped define the scope of community functions required for emergency response. Data were also collected in semi-structured interviews and focus group sessions with different community groups and organisations, emergency management professionals, and officials working in Christchurch City Council. The analysis indicates that relevant functions exist within communities, and that four types of community functions can be used for improving emergency management response. Community functions identified were seen to possess relationships, interactions and qualities lacking in the emergency sector; characteristics that are essential for operational command and control response processes. The major research outcome is the development of a framework that integrates community functions with command and control structure as a contribution to improving response to disruptive events.

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  • Understanding Tsunami hazard knowledge and preparedness : before and after the 2010 Tsunami in Mentawai (Indonesia)

    Panjaitan, Berton Suar Pelita (2017)

    Doctoral thesis
    University of Canterbury Library

    This thesis is about the people from the Mentawai Islands (in Indonesia) in the context of disaster risk reduction. It results from a curiosity to deeply explore the tsunami hazard knowledge existing before the 2010 Mentawai tsunami occurred, and current tsunami preparedness. It also provides theoretical frameworks and key research concepts in relation to the issues. In order to understand the picture of Mentawai in the past and the present, the thesis also includes how the tsunami vulnerability progression has been formed. The progression presents from the era of solitary lives of the people, the era of destroying the traditional beliefs and tools, and up to the current era when the people live in unsafe locations. In order to obtain a full picture of the topics, a qualitative case study was designed with the consideration of how to plot and to show a number of illuminating facts. The people’s reflections and perspectives on their tsunami hazard knowledge before the 2010 tsunami occurred and devastated the islands, and their current tsunami preparedness, were examined. There were a number of substantial facts showing how the research participants captured, shared, and internalized explicit knowledge on tsunami hazards into their tacit knowledge. These processes occurred with little support from the district government and local non-government organizations, and were further impacted by their low socio-economic and educational status. The processes of the knowledge internalization were obviously influenced by their traditional beliefs and personal perceptions. Thus, the implications of the internalization were also different when it came to anticipating tsunami waves. Subsequently, the 2010 tsunami also brought different impacts to the participants. In the context of current measures, tsunami preparedness is applied differently at various levels, even though the people have experienced the 2010 tsunami. At the individual level, the participants mostly ignore their own preparedness, although some of the participants have specific personal efficacy and protective behaviour to avoid tsunami waves. At the household level, some would most likely leave their household members to save themselves, while others would try to help their family members. At the sub-village (dusun) level, the people tend to abandon the evacuation processes. Meanwhile, at the district level, although some important documents exist for the district government to follow, tsunami preparedness measures are less prioritized. The last parts of the study are how the local community of Mentawai can increase their capacity to encounter potential tsunamis. In the absence of modern technologies, the community has a number of traditional strategies to anticipate hazards and various opportunities to reduce their vulnerability. Developing coping capacity is essential for the people through implementing community early warning systems. These systems will provide risk knowledge, strategies to monitor the surroundings, understandable warning communication, and qualified response capability in the event of a tsunami. For the longer term, the leaders and the community need to work hand in hand to create an adaptive mechanism for living in Mentawai. This will be achieved by utilizing and reutilizing their traditional tools and strategies, and taking any opportunity to improve their livelihoods, and consequently, their coping and adaptive capacities to deal with tsunamis.

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  • Estimating leaf area index from airborne laser scanning.

    Pearse, Grant Dennis (2017)

    Doctoral thesis
    University of Canterbury Library

    Leaf area index (LAI) quantifies the amount of leaf surface area per unit ground area. LAI in forest ecosystems regulates the upper limit of possible light interception, atmospheric gas exchange, and primary production. These properties make LAI one of the most important ecophysiological variables with a wide range of potential applications. In the context of forests managed for production, knowledge of LAI offers the potential to align management activities with fundamental biophysical properties. For example, LAI offers the potential to precisely target and monitor management activities such as fertiliser application or disease control. Despite the potential benefits knowledge of LAI offers, usage is seldom seen outside of research applications. A key reason for this is the difficulty in obtaining LAI measurements over large areas, with field based optical methods largely constrained to use under uniform, diffuse sky conditions. Remote sensing of LAI offers one potential solution to obtain large-scale estimates of LAI. However, promising spectral-based approaches have been shown to have limited usefulness for forests with high LAI such as intensively managed coniferous plantations. Airborne laser scanning (ALS) data (lidar) offers enhanced ability to estimate LAI in a range of forest types with a high degree of accuracy, but the optimum methods for estimating LAI from lidar are not well established. This thesis aims to develop and demonstrate a method for estimating LAI from lidar in New Zealand’s intensively managed Pinus radiata D. Don forests. To accomplish this, two distinct areas of research are addressed. First, this thesis addresses the need for acquiring a large number of LAI field measurements covering a range of stand conditions in order to calibrate ALS-LAI models. This was accomplished by validating the use of the newly developed LAI-2200C (LI-COR Biosciences Inc., Lincoln, NE, USA). This instrument allows measurement of LAI under clear sky conditions through the application of a model to correct for the impact of scattered light on gap fraction estimates. This thesis presents the first in situ comparison of LAI measurements acquired under diffuse and clear sky conditions in a coniferous forest. These results were obtained by repeatedly measuring LAI in plots of pure P. radiata in New Zealand. In addition, the thesis presents the first assessment of the importance of acquiring accurate needle spectra to parameterise the scattering correction model. These values were acquired using newly developed methods that allow accurate spectra to be acquired from needle-leaved species via spectroradiometer. The thesis also addresses the stability of needle optical properties with respect to position in the canopy, abaxial and adaxial measurements, and variability between individual trees. The second part of this thesis used a large number of LAI measurements made possible by the new instrumentation to address key questions on the topic of estimating LAI from lidar. To date, most ALS-LAI research has been divided between establishing empirical or physical links between lidar metrics and LAI. This has resulted in a proliferation of proposed methods and lidar metrics for estimating LAI, and few studies have compared these approaches. In addition, factors known to impact ALS-LAI estimation such as the choice of plot parameters have gone relatively unexplored, as has the use of new statistical learning approaches. This thesis attempts to offer the first simultaneous assessment of the optimum combination of lidar metrics, plot parameters, and modelling approaches for estimating LAI from ALS lidar data in P. radiata forests. Results from the instrument validation suggest that the scattering correction model performs well in coniferous forests. Overall, clear sky LAI measurements were higher on average than diffuse sky measurements. However, there was evidence that this difference resulted from a reduction in erroneous readings obtained from the largest outer sensor ring under diffuse sky conditions. Traditionally, data from this part of the instrument have been error-prone and there was some evidence that clear sky LAI measurements offer increased accuracy by reducing scattering induced error across the range of zenith angles observed by the instrument. The method used to obtain spectroradiometer measurements from needle-leaved specimens was well suited to collecting accurate needle reflectance and transmittance for use in the scattering correction model. Use of these values improved agreement between clear and diffuse sky LAI measurements and reduced the magnitude of the largest differences at the extremes of the range. The results demonstrated that P. radiata spectra did not differ significantly with canopy position and were reasonably stable between trees. Measured P. radiata needle spectra are presented as part of this thesis and values are suggested for future users of the LAI-2200C scattering correction model in this forest type. Overall, use of measured spectra in combination with masking of outer ring data allowed LAI to be measured under both clear and diffuse sky conditions; however, clear sky conditions offered considerable reductions in the maximum potential measurement error resulting from changes in sky condition over time and between sensor locations. Results presented in the second part of this thesis demonstrate that LAI can be accurately estimated from lidar data in P. radiata forests. A key finding from this work was that use of standard approaches developed for use in other forest types produced some of the worst models of all those trialled, indicating that successful ALS-LAI estimation in P. radiate depends on careful selection of lidar metrics, plot parameters, and modelling approach. Specifically, results showed that (1) metrics that form a proxy for gap fraction by computing the ratio of returns above and below a chosen height threshold (ratio metrics) were key predictors of LAI; (2) choice of height threshold for ratio metrics strongly impacted model performance and P. radiata appeared to require higher thresholds than other forest types; (3) the concept of a variable height threshold was beneficial in accommodating differences in tree height across plots and led to improved estimates of LAI; (4) a larger fixed plot radius generally improved model performance; (5) use of a variable plot radius linked to instrument view distance was better than any fixed radius trialled; (6) metrics linking lidar penetration to the Beer-Lambert law were only marginally less accurate than empirical models and showed strong predictive ability. This approach may offer a means of estimating LAI without calibration by inverting the Poisson model using gap fraction from lidar and an empirical projection coefficient. Finally, the research found a high level of correlation present between lidar metrics, strongly emphasising the need for modelling approaches robust to these effects. Regularised regression via the elastic net was found to be a useful method for providing both variable and model selection in high-dimensional space while accounting for the presence of high correlation between metrics. Results from models produced by the random forests algorithm were similar to results from elastic net but provided some useful insights into variable importance.

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  • Travelling with the Spirit: Pentecostal Migration Religiosity Between Ghana and Australia

    Dennis, Dorcas (2017)

    Doctoral thesis
    Victoria University of Wellington

    The desire to migrate to foreign lands is widespread within contemporary Ghana. Among the Ghanaians, there is a growing sense that migrating overseas requires spiritual empowerment. Evidence of this development can be seen in the emergence of “passport and visa industries” that depend on the activities of a multitude of religious agents and ritual experts. Correspondingly, Ghanaian religious agents are now constantly generating new strategies designed to meet prospective migrants’ demands. The practice of enlisting the help of religious agents and practices for the purpose of international migration is having a marked effect on the Ghanaian religious landscape in two key ways: first, it has created a demand for religious agents who possess the power to solve migration-related spiritual problems; second, in response to this demand, Ghana's purveyors of spiritual powers have shaped their practices to inspire and enable migration. Using data from extensive fieldwork among members of the Church of Pentecost (CoP) and Power Chapel (PC) in Ghana and Australia, this thesis offers an account of the role of religious narratives and rituals in the experience of Ghanaians migrating abroad, and among Ghanaian migrants in Australia. The thesis argues that the present preoccupation with overseas migration, and its interconnection with religion, is creating a migration religiosity (MR) that inspires and enhances migrations, and which forms the basis for migrants’ extension of Ghanaian religions from the so-called global-South to the global-North. This MR operates in each phase of the migration experience. In the homeland, prospective migrants use MR to facilitate their international travel. On the journey, MR is the source of spiritual protection and safety. MR continues and takes on new roles as migrants use it in meeting new conditions and experiences in their new land. Migrants’ reliance on MR for place-making as they settle into their new lives in the diaspora motivates them to create worshiping Cells. These Cells become the setting in which Ghanaian migrants reformulate their religious traditions, and from which they launch proselytizing practices or reverse missions to the host community.

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