2,665 results for ResearchSpace@Auckland, Modify

  • Life and living in advanced age: A cohort ctudy in New Zealand - Te puawaitanga o nga tapuwae kia ora tonu, LILACS NZ: Study protocol

    Hayman, Karen; Kerse, Ngaire; Dyall, Lorna; Kepa, M; Teh, Ruth; Wham, C; Wright-St Clair, V; Wiles, Janine; Keeling, S; Connolly, Martin; Wilkinson, TJ; Moyes, Simon; Broad, Joanna; Jatrana, S (2012)

    Journal article
    The University of Auckland Library

    Background The number of people of advanced age (85 years and older) is increasing and health systems may be challenged by increasing health-related needs. Recent overseas evidence suggests relatively high levels of wellbeing in this group, however little is known about people of advanced age, particularly the indigenous M??ori, in Aotearoa, New Zealand. This paper outlines the methods of the study Life and Living in Advanced Age: A Cohort Study in New Zealand. The study aimed to establish predictors of successful advanced ageing and understand the relative importance of health, frailty, cultural, social & economic factors to successful ageing for M??ori and non-M??ori in New Zealand.

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  • Sedimentology and formation of lagoonal platform reef islands in Huvadhoo Atoll, Maldives

    Liang, Yiqing (2016)

    Doctoral thesis
    The University of Auckland Library

    Sediment samples from the reef platform and island cores were collected from two lagoonal reef islands in Huvadhoo Atoll, Maldives, in order to investigate island evolution and building processes in a region where detailed sedimentary and chronology data do not yet exist. The chronostratigraphy of the study islands was resolved using sedimentary data from field samples, combined with radiocarbon ages of sediments and ground penetrating radar records of the island subsurface. Further, this study is the first to apply scanning electron microscopy and elemental mapping in the evaluation of single constituent dating of Halimeda spp. in order to investigate its suitability for inferring depositional chronology on reef islands. Chronostratigraphic results indicate that the lagoonal reef islands on Huvadhoo Atoll formed around 3000 years ago and reached their current dimensions by 350 cal yr BP. A three-phase model of island evolution was developed in relation to mid-Holocene sea-level rise, which presents the first incidence of island building over multiple phases of sea-level change in the Indian Ocean. Medium-scale (decadal) shoreline sediment redistribution identified from morphological field mapping and satellite imagery provide clues to the building processes that occurred during island evolution, and suggest frequent reworking of island sediments over the course of island building. Similar compositional properties of reef flat and island sediments suggest a reef-island link and that the study islands are still being maintained by their surrounding reefs at present. The formation of the lagoonal reef islands in Huvadhoo Atoll during various stages of sea-level change, along with the potential for shoreline adjustment and evidence of contemporary reef connectivity, suggest enhanced resilience of Maldivian reef islands in response to projected sea-level rise.

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  • Kindness Matters: Investigating the mental and physical health benefits of self-compassion in diabetes

    Friis, Anna (2016)

    Doctoral thesis
    The University of Auckland Library

    Mood disturbances among diabetes patients are both common and problematic, compounding emotional suffering and potentially leading to complications in physical health. Despite high prevalence, however, current treatment options for the management of depression are limited; evidence for psychosocial interventions that concurrently improve both psychological and physiological health metrics is sorely lacking. The work presented in the context of this thesis sought to address this deficit by investigating the mental and physical health benefits of self-compassion in diabetes patients through a series of theoretical, cross-sectional, and experimental studies. The primary aims of this programme of study were to establish: (1) whether selfcompassion predicts better mental and physical health outcomes among diabetes patients and, if so, (2) whether a self-compassion intervention improved these outcomes for patients. The first contribution (Study 1) reviewed the literature pertaining to depression and low mood among diabetes patients and presented a theoretical rationale suggesting that self-compassion is well-suited to the challenges of diabetes selfmanagement, and that enhancing this characteristic should have psychological, behavioural, and physiological benefits. Study 2, a cross-sectional study conducted primarily with Type 1 diabetes patients then tested some of these hypothesized relationships. Analysis showed (1), that diabetes-specific distress was a better predictor of HbA1c than depression and (2), that self-compassion moderated the link between diabetes-specific distress and HbA1c such that the link between distress and poorer metabolic outcomes was weakened among those with greater trait selfcompassion. In Study 3, the effects of a brief self-compassion induction on mood and motivation to undertake a common health behaviour were tested in a laboratory study among healthy participants. While the self-compassion intervention improved mood, results were not consistent with the notion that self-compassion, compared to selfcriticism, would positively improve behavioural motivation, Thus, the final study (Study 4), a randomized controlled trial, tested the effects of a more substantial and standardized ???dose??? of self-compassion training ??? mindful self-compassion. Analyses showed that the eight-week training intervention improved both psychological and physiological outcomes, with reductions in depression, distress, and HbA1c in the intervention arm; effects were sustained at three months follow-up. Taken together, these studies are the first to demonstrate that self-compassion both predicts and causes reductions in depression and diabetes-specific distress among diabetes patients while concurrently improving metabolic outcomes. The RCT provides further evidence that self-compassion is a characteristic that can be developed with training. However, while highlighting the relevance of self-compassion to a patient population that often struggles with mood issues and related complications, further work is required to understand the pathways by which benefits might be exerted; effects on behavioural motivations in the laboratory study were not clearly evident. Overall, while self-compassion may be an important clinical aid for assisting patients more effectively cope with the distress of their condition, further work is required to better understand mediating psychological, behavioural, and biological pathways.

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  • Improving adherence and asthma outcomes in school aged children with asthma

    Chan, Amy (2016)

    Doctoral thesis
    The University of Auckland Library

    Asthma is one of the most common chronic conditions in children. Effective treatments are available, the most important of which are inhaled corticosteroids, which reduce morbidity and mortality. Despite the availability of effective preventive therapies, asthma control continues to be poor, primarily due to poor adherence. Interventions have been developed to improve adherence; however, changes have been modest, or not sustained. Where there have been significant increases in adherence, these have not translated to improvements in outcomes. A novel approach to adherence support is needed. Electronic monitoring devices (EMDs) have risen to prominence over the last decade, assuming an important role in adherence measurement and intervention. The ability of EMDs to provide objective, real-time data and user feedback places EMDs at the forefront of contemporary adherence interventions. This thesis discusses adherence in chronic disease, specifically asthma, and the role of EMDs in adherence promotion. Studies using EMDs to improve adherence in asthma have shown improvements in adherence, but the link to outcomes has been inconclusive. This thesis presents the main findings from a randomised controlled trial (RCT) investigating the use of an EMD in children with asthma. The results from this trial provide the first unequivocal evidence of the beneficial effects of EMDs on clinical outcomes. It provides a direction for future adherence research, focusing on the effect of EMDs on clinical outcomes, beyond adherence promotion. This thesis also presents the first performance and patient acceptability data for EMDs in children. The positive findings highlight the potential for EMDs to be used outside of the research setting, though key issues of quality control, usability and cost-effectiveness need to be addressed before EMDs can be integrated into practice. Other factors influencing adherence are also discussed. This study found associations between higher adherence and female sex, Asian ethnicity, smaller household size and a younger age at diagnosis. These findings can help identify those at risk of nonadherence to help target adherence interventions. This thesis highlights areas of knowledge growth and areas where questions remain unanswered. It provides a platform for future research, presenting new possibilities for improving medication adherence and clinical outcomes

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  • Korea???s Growing Role(s) on the World Stage ??? South Korean Identity and Global Foreign Policy in the Early 21st Century

    Flamm, Patrick (2017)

    Doctoral thesis
    The University of Auckland Library

    South Korea is usually seen as a ???shrimp amongst whales???, a minor player with limited agency in regional and global affairs. After colonization, the Korean War, national division and decades of military rule in the 20th century, however, South Korea today contributes to international peace and security with its peacekeeping troops and has successfully promoted its ???green growth??? vision of sustainable development. The rising status of Korea begs the question about related changes in the South Korean identity or ???sense of self??? in the world. In the respective International Relations and Korean Studies literatures this question has not yet been fully addressed beyond hopes for South Korea to be a future cornerstone of the liberal international order. Further, a wide variety of ???identity??? conceptualizations has been leading to ???definitional anarchy??? as well as ???confusion and analytical ambiguity??? in the study of identity in general and South Korean international identity in particular. This thesis presents a theoretically rigorous and empirically rich approach for the inquiry into state identity through the utilization of conceptual tools from symbolic-interactionist role theory as a contribution to the research on state identity and foreign policy. By focusing on South Korean agency and domestic self-identification practices, the empirical analysis at hand is able to provide a comprehensive account of the various identity narratives and role conceptions at play in South Korea???s global engagement in peacekeeping and climate diplomacy, complementing more systemic identity approaches such as the literature on norms and socialization. It argues that in the cases of peacekeeping and climate diplomacy South Korea???s identity as an international actor has been dominated by practices of self-identification that locate the country at the brink of advanced countries, aspiring to lead the rest of the world on the basis of the Korean developmental experience, but with the overall objective to maintain national autonomy in a changing regional and global context. Finally, this study is a contribution to the Korean Studies literature on how South Korea confronts globalization on the level of identity and politics.

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  • Super Resolution Imaging of Cardiac Ventricular Myocyte Calcium Handling Systems

    Hou, Yufeng (2016)

    Doctoral thesis
    The University of Auckland Library

    The ventricular cardiac myocyte is the most prominent cell of the heart by volume and weight and is responsible for the contractive force necessary to pump blood around the body. Operation of the ventricular myocyte centre occurs through the coupling of electrical activity and the subsequent mechanical contraction, a process known as excitation contraction coupling (EC Coupling). EC coupling centre around the precise handling of both extracellular and internal calcium ion stores in a process called calcium induced calcium release (CICR). This process is dependent on the precise nanometer scale arrangement of the Ryanodine receptor (RyR) protein within the SR membrane which act as the primary calcium release channel for the SR calcium stores. This thesis aims to investigate the ryanodine receptor and associated structures using super resolution imaging modality to investigate nanoscale changes in structural distribution. Section one focuses on the imaging of the Z disc ??? the region of localisation for RyR release sites. Results show thicknesses of z disc were measured at 100 nm with transverse arrangement showing all fibril cores being within a unified 500 nm distance band. The second section demonstrates the distribution of RyR proteins in transverse rat cardiac myocyte tissue sections. Results demonstrated a large variation in cluster sizes with approximate exponential distribution. Mean cluster size was 63 RyR with mean edge to edge separation of 130 nm in general agreement with previous confocal data. Colocalisation of RyR with the T-tubule ??? SR crosslinking protein JPH showed a high level of colocalisation compared with an idealised colocalisation simulation of RyR vs RyR (61% vs 78%). Data is consolidated with diffraction limited data highlighting the detection falloff at smaller cluster sizes. The final section investigated differences in human RyR distribution for normal, idiopathic dilated cardiomyopathy, and rat cells. Results showed little change in cluster size distribution between all three cases, however a change in nearest adjacent neighbour distances were observed. A reduction in colocalisation between JPH and RYR is further seen in humans as compared with rats. These results highlight the subtle structural features seen in the arrangement of RyR clusters, and how super resolution imaging provides greater clarity and additional details on top of the previous attempts at analysis with conventional microscopes.

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  • Economic evaluation of an exercise-counselling intervention to enhance smoking cessation outcomes: The Fit2Quit trial

    Leung, W; Roberts, V; Gordon, LG; Bullen, Christopher; McRobbie, H; Prapavessis, H; Jiang, Yannan; Maddison, R (2017)

    Journal article
    The University of Auckland Library

    In the Fit2Quit randomised controlled trial, insufficiently-active adult cigarette smokers who contacted Quitline for support to quit smoking were randomised to usual Quitline support or to also receive ???10 face-to-face and telephone exercise-support sessions delivered by trained exercise facilitators over the 24-week trial. This paper aims to determine the cost-effectiveness of an exercise-counselling intervention added to Quitline compared to Quitline alone in the Fit2Quit trial.Within-trial and lifetime cost-effectiveness were assessed. A published Markov model was adapted, with smokers facing increased risks of lung cancer and cardiovascular disease.Over 24??weeks, the incremental programme cost per participant in the intervention was NZ$428 (US$289 or ???226; purchasing power parity-adjusted [PPP]). The incremental cost-effectiveness ratio (ICER) for seven-day point prevalence measured at 24-week follow-up was NZ$31,733 (US$21,432 or ???16,737 PPP-adjusted) per smoker abstaining. However, for the 52% who adhered to the intervention (???7 contacts), the ICER for point prevalence was NZ$3,991 (US$2,695 or ???2,105 PPP-adjusted). In this adherent subgroup, the Markov model estimated 0.057 and 0.068 discounted quality-adjusted life-year gains over the lifetime of 40-year-old males (ICER: NZ$4,431; US$2,993 or ???2,337 PPP-adjusted) and females (ICER: NZ$2,909; US$1,965 or ???1,534 PPP-adjusted).The exercise-counselling intervention will only be cost-effective if adherence is a minimum of ???7 intervention calls, which in turn leads to a sufficient number of quitters for health gains.Australasian Clinical Trials Registry Number ACTRN12609000637246.

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  • E-cigarettes for the management of nicotine addiction

    Knight-West, O; Bullen, Christopher (2016-08)

    Journal article
    The University of Auckland Library

    In this review, we discuss current evidence on electronic cigarettes (ECs), a rapidly evolving class of nicotine delivery system, and their role in managing nicotine addiction, specifically in helping smokers to quit smoking and/or reduce the amount of tobacco they smoke. The current evidence base is limited to three randomized trials (only one compares ECs with nicotine replacement therapy) and a growing number of EC user surveys (n=6), case reports (n=4), and cohort studies (n=8). Collectively, these studies suggest modest cessation efficacy and a few adverse effects, at least with the short-term use. On this basis, we provide advice for health care providers on providing balanced information for patients who enquire about ECs. More research, specifically well-conducted large efficacy trials comparing ECs with standard smoking cessation management (eg, nicotine replacement therapy plus behavioral support) and long-term prospective studies for adverse events, are urgently needed to fill critical knowledge gaps on these products.

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  • News exposure predicts anti-Muslim prejudice

    Shaver, JH; Sibley, Christopher; Osborne, Daniel; Bulbulia, J (2017)

    Journal article
    The University of Auckland Library

    News coverage of Islamic extremism is reigniting debates about the media's role in promoting prejudice toward Muslims. Psychological theories of media-induced prejudice date to the 1950's, and find support from controlled experiments. However, national-scale studies of media effects on Muslim prejudice are lacking. Orthogonal research investigating media-induced prejudice toward immigrants has failed to establish any link. Moreover, it has been found that people interpret the news in ways that confirm pre-existing attitudes, suggesting that media induced Muslim prejudice in liberal democracies is unlikely. Here, we test the association between news exposure and anti-Muslim prejudice in a diverse national sample from one of the world's most tolerant societies, where media effects are least likely to hold (N = 16,584, New Zealand). In support of media-induced Islamophobia, results show that greater news exposure is associated with both increased anger and reduced warmth toward Muslims. Additionally, the relationship between media exposure and anti-Muslim prejudice does not reliably vary with political ideology, supporting claims that it is widespread representations of Muslims in the news, rather than partisan media biases, that drives anti-Muslim prejudice.

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  • Searching for standards in the NCEA: Assessing musical performance

    McPhail, Graham (2008)

    Journal article
    The University of Auckland Library

    In this paper it is argued that the theory and practice of standardsbased assessment within the context of the National Certificate of Educational Achievement (NCEA) has not been clearly articulated for teachers. The difficulty of specifying and promulgating standards in appropriate forms and the lack of clarity present in the support materials and training provided for teachers are examined. Through the analysis of an internally assessed Music Achievement Standard currently available in the NCEA, it will be argued that standards can be neither definitively described nor easily assessed, but that a credible standard is reliant on a number of components. It is the combination of these components that is significant if standards are to function effectively in summative contexts, particularly for high stakes national qualifications. The support materials and training music teachers received during the introduction of the NCEA lacked clarity and this has resulted in a weak link in the chain of components required for a robust assessment system. Teachers need access to quality support materials and the opportunity for on-going professional development in relation to standardsbased assessment.

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  • Engagement and recruitment of M??ori and non-M??ori people of advanced age to LiLACS NZ

    Dyall, Lorna; Kepa, M; Hayman, Karen; Teh, Ruth; Moyes, Simon; Broad, Joanna; Kerse, Ngaire (2013-04)

    Journal article
    The University of Auckland Library

    Life and Living in Advanced Age: A Cohort Study in New Zealand (LiLACS NZ) aims to determine the predictors of successful advanced ageing and understand the trajectories of wellbeing in advanced age. This paper reports recruitment strategies used to enrol 600 M??ori aged 80-90 years and 600 non-M??ori aged 85 years living within a defined geographic boundary.

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  • Design of optimized hypoxia-activated prodrugs using pharmacokinetic/pharmacodynamic modeling

    Foehrenbacher, A; Secomb, TW; Wilson, William; Hicks, Kevin (2013-12-27)

    Journal article
    The University of Auckland Library

    Hypoxia contributes to resistance of tumors to some cytotoxic drugs and to radiotherapy, but can in principle be exploited with hypoxia-activated prodrugs (HAP). HAP in clinical development fall into two broad groups. Class I HAP (like the benzotriazine N-oxides tirapazamine and SN30000), are activated under relatively mild hypoxia. In contrast, Class II HAP (such as the nitro compounds PR-104A or TH-302) are maximally activated only under extreme hypoxia, but their active metabolites (effectors) diffuse to cells at intermediate O2 and thus also eliminate moderately hypoxic cells. Here, we use a spatially resolved pharmacokinetic/pharmacodynamic (SR-PK/PD) model to compare these two strategies and to identify the features required in an optimal Class II HAP. The model uses a Green's function approach to calculate spatial and longitudinal gradients of O2, prodrug, and effector concentrations, and resulting killing in a digitized 3D tumor microregion to estimate activity as monotherapy and in combination with radiotherapy. An analogous model for a normal tissue with mild hypoxia and short intervessel distances (based on a cremaster muscle microvessel network) was used to estimate tumor selectivity of cell killing. This showed that Class II HAP offer advantages over Class I including higher tumor selectivity and greater freedom to vary prodrug diffusibility and rate of metabolic activation. The model suggests that the largest gains in class II HAP antitumor activity could be realized by optimizing effector stability and prodrug activation rates. We also use the model to show that diffusion of effector into blood vessels is unlikely to materially increase systemic exposure for realistic tumor burdens and effector clearances. However, we show that the tumor selectivity achievable by hypoxia-dependent prodrug activation alone is limited if dose-limiting normal tissues are even mildly hypoxic.

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  • Likelihood of residential aged care use in later life: a simple approach to estimation with international comparison

    Broad, Joanna; Ashton, Toni; Gott, Caryl; McLeod, H; Davis, Peter; Connolly, Martin (2015-08)

    Journal article
    The University of Auckland Library

    In New Zealand (NZ), place of death among decedents aged 65+ years has been reported as residential aged care (RAC, 38%), acute hospital (34%) or elsewhere (28%). However, lifetime risk of use of RAC (or nursing homes) is unknown. A simple method of estimation is demonstrated for NZ and Australia, with comparisons to other countries.Deaths of RAC residents in acute hospitals were estimated for NZ from four separate studies and added to deaths occurring in RAC, to derive the likelihood of using RAC after age 65 years. Academic and other sources were searched for comparative reports.An estimated 18% of RAC residents died in acute hospital in NZ. When added to those who died in RAC, the proportion using RAC for late-life care was estimated at over 47% (66% if aged 85+ years). Of 12 US reports, the median report was 41%. Elsewhere, Finland was 47%, UK 28%, Australia 34% to 53%, and Germany 22% & 26%.Simple estimation using existing data demonstrates that RAC in late life is common.Late-life care services will continue to evolve. Monitoring RAC utilisation is necessary for informed debate about palliative care provision in RAC, use of hospital by RAC residents and for planning and policy setting.

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  • Early response in cognitive-behavior therapy for syndromes of medically unexplained symptoms

    Kleinst??uber, Maria; Lambert, MJ; Hiller, W (2017-05-25)

    Journal article
    The University of Auckland Library

    BACKGROUND: Early dramatic treatment response suggests a subset of patients who respond to treatment before most of it has been offered. These early responders tend to be over represented among those who are well at termination and at follow-up. Early response patterns in psychotherapy have been investigated only for a few of mental disorders so far. The main aim of the current study was to examine early response after five therapy-preparing sessions of a cognitive behavior therapy (CBT) for syndromes of medically unexplained symptoms (MUS). METHODS: In the context of a randomized, waiting-list controlled trial 48 patients who suffered from ???3 MUS over ???6??months received 5 therapy-preparing sessions and 20 sessions of CBT for somatoform disorders. They completed self-report scales of somatic symptom severity (SOMS-7??T), depression (BDI-II), anxiety (BSI), illness anxiety and behavior (IAS) at pre-treatment, after 5 therapy-preparing sessions (FU-5P) and at therapy termination (FU-20??T). RESULTS: The current analyses are based on data from the treatment arm only. Repeated measure ANOVAs revealed a significant decrease of depression (d??=??0.34), anxiety (d??=??0.60), illness anxiety (d??=??0.38) and illness behavior (d??=??0.42), but no change of somatic symptom severity (d??=??-0.03) between pre-treatment and FU-5P. Hierarchical linear multiple regression analyses showed that symptom improvements between pre-treatment and FU-5P predict a better outcome at therapy termination for depression and illness anxiety, after controlling for pre-treatment scores. Mixed-effect ANOVAs revealed significant group*time interaction effects indicating differences in the course of symptom improvement over the therapy between patients who fulfilled a reliable change (i.e., early response) during the 5 therapy-preparing sessions and patients who did not reach an early reliable change. Demographic or clinical variables at pre-treatment were not significantly correlated with differential scores between pre-treatment and FU-5P (-.23???????r???????.23). CONCLUSIONS: Due to several limitations (e.g., small sample size, lack of a control group) the results of this study have to be interpreted cautiously. Our findings show that reliable changes in regard to affective-cognitive and behavioral variables can take place very early in CBT of patients with distressing MUS. These early changes seem to be predictive of the outcome at therapy termination. Future studies are needed in order to replicate our results, and to identify mechanisms of these early response patterns in somatoform patients. TRIAL REGISTRATION: ISRCTN. ISRCTN17188363 . Registered retrospectively on 29 March 2007.

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  • Understanding the Attributes of Implementation Frameworks to Guide the Implementation of a Model of Community-based Integrated Health Care for Older Adults with Complex Chronic Conditions: A Metanarrative Review

    McKillop, Ann; Shaw, J; Sheridan, Nicolette; Gray, CS; Carswell, Peter; Wodchis, WP; Connolly, Martin; Denis, J-L; Baker, GR; Kenealy, Timothy (2017-06-27)

    Journal article
    The University of Auckland Library

    Many studies have investigated the process of healthcare implementation to understand better how to bridge gaps between recommended practice, the needs and demands of healthcare consumers, and what they actually receive. However, in the implementation of integrated community-based and integrated health care, it is still not well known which approaches work best.We conducted a systematic review and metanarrative synthesis of literature on implementation frameworks, theories and models in support of a research programme investigating CBPHC for older adults with chronic health problems.Thirty-five reviews met our inclusion criteria and were appraised, summarised, and synthesised. Five metanarratives emerged 1) theoretical constructs; 2) multiple influencing factors; 3) development of new frameworks; 4) application of existing frameworks; and 5) effectiveness of interventions within frameworks/models. Four themes were generated that exposed the contradictions and synergies among the metanarratives. Person-centred care is fundamental to integrated CBPHC at all levels in the health care delivery system, yet many implementation theories and frameworks neglect this cornerstone.The research identified perspectives central to integrated CBPHC that were missing in the literature. Context played a key role in determining success and in how consumers and their families, providers, organisations and policy-makers stay connected to implementing the best care possible.All phases of implementation of a new model of CBPHC call for collaborative partnerships with all stakeholders, the most important being the person receiving care in terms of what matters most to them.

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  • All-optical photoacoustic and laser-ultrasonic imaging in heterogeneous tissue

    Johnson, Jami (2017)

    Doctoral thesis
    The University of Auckland Library

    Elastic waves are used across a broad spectrum in medicine to non-invasively probe and image tissues up to centimeters deep. Ultrasonic (US) imaging is the most well-known modality used to image acoustic density and velocity contrasts. US is useful for imaging overall structure in tissue, however, acoustic contrasts are relatively low in biological tissue. In contrast, optical properties are highly specific, but imaging with light is typically limited to depths of about 1mm. Therefore, we aim to create images of both acoustic and optical properties centimeters deep in tissue non-invasively. Laser-induced acoustic waves are generated by the absorption of nanosecond pulses of laser light by biological tissue. The transient thermoelastic expansion that results propagates as a pressure wave. The wavelength of the source laser can be tuned such that absorption occurs either primarily at the tissue surface, generating a laser-ultrasound (LUS) wave, or deep inside to create photoacoustic (PA) waves due to absorption by embedded tissue chromophores. LUS waves can be thought of as mini-explosions at the tissue surface, much like the man-made explosions used by seismologists to image the subsurface of the earth. Likewise, PA waves are analogous to mini-earthquakes, originating from below the surface and propagating to the boundary where they are detected. We obtain optical absorption properties by inverting for the location of PA sources, and structural images by reconstructing the location of LUS scattering/reflection. The reconstruction methods utilized for PA and LUS are accordingly inspired by seismology. Reverse-time migration is adapted for reflection-mode LUS imaging to improve the imaging aperture and reduce artifacts. The velocity model is optimized in the LUS reconstruction, and subsequently applied to reconstruct PA images with time-reversal. Laser-generated PA and LUS waves are broadband, allowing for high-resolution images to be reconstructed. Detection using contacting piezoelectric transducers allows real-time imaging with high sensitivity, however, the frequency bandwidth is relatively narrow. Optical detectors provide an alternative to piezoelectric transducers when a small sensor footprint, large frequency bandwidth, or non-contacting detection is required. We introduce a fully non-contact gas-coupled laser acoustic detector (GCLAD) for medical imaging that utilizes optical beam deflection. We describe the underlying principles of GCLAD and derive a formula for quantifying the surface displacement from a remote, line-integrated GCLAD measurement. We quantify the surface displacement with GCLAD in a LUS experiment, which shows 94% agreement to line-integrated data from a commercial laser-Doppler vibrometer point detector. We further demonstrate the feasibility of PA imaging of an artery-sized absorber using GCLAD 5:8 cm from a phantom surface. Additionally, we advance all-optical imaging techniques using a laser-Doppler vibrometer point-detector. While previous reflection-mode all-optical systems use a confocal source and detection beam, we introduce nonconfocal acquisition to obtain angle-dependent data. We demonstrate that nonconfocal acquisition with a single source improves the signal-to-noise of low-amplitude PA and LUS signals using a normal-moveout processing technique. Incorporating multiple sources in this geometry allows us to apply reverse-time migration to reconstruct LUS images. We demonstrate this methodology with both a numerical model and tissue phantom experiment to image a steep-curvature vessel with a limited aperture 2 cm beneath the surface. Nonconfocal imaging demonstrates improved focusing by 30% and 15% compared to images acquired with a single LUS source in the numerical and experimental LUS images. PA images are straightforward to acquire with the all-optical system by tuning the source wavelength or the surface properties, which we reconstruct with time reversal. Therefore, we demonstrate broadband high-resolution PA and LUS imaging with this all-optical system. Subsequently, we demonstrate PA and LUS imaging of atherosclerotic plaque ex vivo. We apply our nonconfocal PA and LUS acquisition and reconstruction techniques to a fixed human carotid artery embedded in an agar tissue phantom. The LUS image provides structural information about acoustic contrasts, in which we distinguish between the layers of the artery wall and detect calcification. PA imaging is sensitive to optical absorbers, such as lipids and hemoglobin. In this ex vivo example, we image a synthetic absorber analogous to hemoglobin in the artery. We compare our nonconfocal LUS approach to confocal LUS imaging, and see a significant improvement in contrast and resolution, and reduce the appearance of artifacts. Further, we observe that LUS aids in the interpretation of PA images, specifically to identify reflection artifacts. We validate our results with both x-ray computed tomography and histology. Finally, we introduce a method for removing reflection artifacts in PA imaging altogether. We adapt a method known as Marchenko imaging developed for two-way imaging problems in seismology to the PA source inversion problem. Iterative convolutions of PA data with nonconfocal LUS predicts reflection artifacts, which we subtract from the PA image. We eliminate dominant artifacts in numerical data using a single iteration of the Marchenko scheme. Overall, we present novel methods for all-optical PA and LUS imaging including instrumentation, acquisition, image processing, and reconstruction. We present a new non-contact optical detector for medical imaging. We demonstrate unconventional experimental methods, combined with powerful imaging methods inspired by seismology to improve the resolution and contrast of LUS images and reduce artifacts in PA and LUS imaging. Furthermore, we demonstrate the potential for all-optical PA and LUS imaging to address the clinical need for non-invasive, multi-component imaging of vulnerable atherosclerotic plaque.

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  • Diet, nutrition, and growth in the temperate rocky reef fish Girella tricuspidata (Girellidae)

    Salewski, Tabea (2017)

    Doctoral thesis
    The University of Auckland Library

    This thesis investigated the relationship between nutritional ecology and growth in the marine reef fish Girella tricuspidata (Girellidae) found in northern New Zealand and temperate eastern Australia. The aim was to establish how diet, nutrition, and temperature affect the demography of the species/population, and in particular to test two hypotheses. The Temperature-Constraint Hypothesis predicts that digestion of algal foods in marine herbivorous fish is constrained by temperature at higher latitudes, and therefore restricts growth, whereas the Temperature-Size Rule predicts that temperature determines growth rate. This thesis investigated the effects of changes in diet and nutrition on growth and longevity between two populations of Girella tricuspidata, and how diet and nutrient intake were scheduled across the year in relation to growth and reproduction. The aim was also to identify the strategies omnivorous fishes on a mainly herbivorous diet employ to survive on a diet considered nutritionally poor and difficult to digest. Spatial differences in growth between populations were analysed to examine the effects of nutrition and temperature on growth. Two populations (coastal and offshore, about 50 km apart) were sampled in the Outer Hauraki Gulf in north-eastern New Zealand. Diet analysis of stomach content samples revealed an omnivorous diet, with fish ingesting a wide array of food items. The diet consisted mainly of small epiphytic Rhodophyta, Abroteia suborbicularis in particular, complemented by a considerable amount of animal material. Epiphytes on Carpophyllum maschalocarpum varied in abundance seasonally, but the pattern differed between two coastal sampling locations, indicating that epiphytes are available throughout the year. Ulva species (Chlorophyta), which are ususally considered to be the preferred food, were also ingested but were not a dominant dietary item. Seasonal changes in diet compositions were mainly due to the seasonal appearance of salps, which formed a major part of the diet between spring and autumn. Salps appeared slightly earlier in stomach contents of fish offshore, where abundances peaked earlier in the season due to the hydrology of the Hauraki Gulf. When salps were not available fish increased their intake of other animal matter such as crustaceans. Nutrient analysis (carbon, nitrogen, lipid, ash) of stomach contents revealed that diet items differed in nutrient compositions and that diet composition varied between locations and seasons. However G. tricuspidata mixed diet items so that the nutrient composition remained nearly constant throughout the year and was similar for both populations. The condition factor based on gutted weight remained nearly constant throughout the year, but increased slightly in spring based on the total weight, a pattern associated with gonad development. Spawning peaked in December. Nutrient demand was expected to increase during spawning time in spring, but relative gut content mass and nutrient composition remained constant in both populations, indicating consistent nutrient intake throughout the year. Intake of salps, which contain high lipid levels needed for reproduction, increased during spawning time. Relative gut length varied between seasons in both populations, and coastal fish had longer guts in relation to body length than offshore fish. G. tricuspidata is a long-lived temperate reef fish that displays an asymptotic growth pattern. Annual increments in sagittal otoliths revealed 54 years of age for the oldest fish, an offshore specimen, representing the maximum-recorded age reported for G. tricuspidata. The oldest fish caught from the coastal population was 44 years. Otolith chronologies showed that increment widths reflected increased growth during warmer years, while colder years resulted in increment widths narrower than average. Growth increment width indices correlated strongly with summer sea surface temperatures. There was a significant difference in growth rate between the coastal and offshore populations, but not between sexes. Calculations of the reparameterized von Bertalanffy growth function parameters showed that coastal fish grew faster as juveniles. Population growth curves crossed at about seven years. Coastal fish reached their adult size at about 13 years and offshore fish at 18 years. Coastal fish had smaller mean adult sizes (291.5 mm SL) than offshore fish (326.3 mm SL). The determining factor was most likely microhabitat. Juvenile coastal fish spend their first two years exclusively inside Whangateau Harbour before moving to the open coast, and adult fish also spend time inside the Harbour. Summer sea surface temperatures are about 2.9??C warmer inside Whangateau Harbour than along the coast and at the offshore location. This study suggests that G. tricuspidata selectively feed on protein-rich algae and also employ a complementary feeding strategy gaining the majority of their energy from epiphytic algae. Epiphytic algae are complemented with animal matter rich in protein and lipid. Data on resource availability, nutrition, and digestion was inconsistent with the Temperature-Constraint Hypothesis. Rather, temperature variation influenced growth variation over the spatial scale of the study, and temperature differences between habitats were most likely the factor driving observed growth variation between the two populations, thereby supporting the Temperature-Size Rule.

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  • Supramolecular thermoplastics and thermoplastic elastomer materials with self-healing ability based on oligomeric charged triblock copolymers

    Voorhaar, Lenny; Diaz, MM; Leroux, F; Rogers, S; Abakumov, AM; Van Tendeloo, G; Van Assche, G; Van Mele, B; Hoogenboom, R (2017-05-26)

    Journal article
    The University of Auckland Library

    Supramolecular polymeric materials constitute a unique class of materials held together by non-covalent interactions. These dynamic supramolecular interactions can provide unique properties such as a strong decrease in viscosity upon relatively mild heating, as well as self-healing ability. In this study we demonstrate the unique mechanical properties of phase-separated electrostatic supramolecular materials based on mixing of low molar mass, oligomeric, ABA-triblock copolyacrylates with oppositely charged outer blocks. In case of well-chosen mixtures and block lengths, the charged blocks are phase separated from the uncharged matrix in a hexagonally packed nanomorphology as observed by transmission electron microscopy. Thermal and mechanical analysis of the material shows that the charged sections have a Tg closely beyond room temperature, whereas the material shows an elastic response at temperatures far above this Tg ascribed to the electrostatic supramolecular interactions. A broad set of materials having systematic variations in triblock copolymer structures was used to provide insights in the mechanical properties and and self-healing ability in correlation with the nanomorphology of the materials.

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  • One-pot synthesis of charged amphiphilic diblock and triblock copolymers via high-throughput Cu(0)-mediated polymerization

    Voorhaar, Lenny; Hoogenboom, R (2017-08)

    Journal article
    The University of Auckland Library

    Block copolymers containing functionalized monomers, for example those containing charged groups, can be used for many purposes, one of which is the design of polymeric supramolecular materials based on electrostatic interactions. In this paper the synthesis of diblock copolymers and ABA-triblock copolymers containing poly(n-butyl acrylate) as a first or middle block and poly(2-(dimethylamino)ethyl acrylate), poly(1-ethoxyethyl acrylate) and poly(1-ethoxyethyl-2-carboxyethyl acrylate) as second or outer blocks, resulting in block copolymers that can contain positive or negative charges, is reported. The polymerizations were performed and optimized via one-pot sequential monomer addition reactions via Cu(0)-mediated polymerization using an automated parallel synthesizer. Different initiators, monomer concentrations and polymerization times were tested. While a bromide-containing initiator led to the best results for most monomers, when polymerizing 2-(dimethylamino)ethyl acrylate the use of a chloride-containing initiator was necessary. Due to the slower polymerization using this initiator, a longer polymerization time was needed before addition of the second monomer. Using the optimized conditions, the diblock and triblock copolymers could be synthesized with good control over molecular weight and dispersities around 1.1 were obtained.

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  • Early Writers in Northern Communities: Ways Teachers Might View and Reflect on Writers??? Representations

    Parr, Judith (2017)

    Journal article
    The University of Auckland Library

    ???What did I write???? is the title of a seminal book (Clay, 1975), illustrating how we can learn what children know about print, in part, from their representations. Children???s writing is socially and culturally situated; play is one context shown to help develop the use of symbol systems. A framing with several lenses is designed and applied to illustrate to teachers ways to consider the samples of early writing accompanying the play of young children in remote Northern communities in Canada. There is consideration of how information could be used to inform and optimize educative actions in such learning contexts.

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