2,714 results for ResearchSpace@Auckland, Modify

  • An Indoor Wireless Wi-Fi Energy Harvesting System with Super Capacitor Backup

    Abd Kadir, Ermeey (2017)

    Doctoral thesis
    The University of Auckland Library

    Currently, researchers are highly interested in finding alternative methods of powering lowpower wireless devices. One of the promising methods is radio frequency energy harvesting (RFEH). The harvesting system, which is a combination of a rectenna, a power processing circuit and an energy storage device, harvests available radio energy in the atmosphere of the wireless devices. This thesis focusses on the system design, analysis, and measurement of a RFEH system which operates in an indoor environment. The thesis is divided into three major parts. The first part is about approximating the amount of incident power received on the surface of a harvesting antenna. Previously, received power at a harvesting antenna location is determined using the Friis equation in which the equation considers antenna gains, the output power of a transmitting antenna, and the transmittingreceiving antenna distance. The distance between the antennae is related to the free space loss, and it is used in estimating the received power. For the thesis, the approximation of incident power on the harvesting antenna is investigated further by considering the antenna dimensions, its elevation from the reference plane, which is the ground level, its distance to the transmitter, and misalignments. These three factors contribute to the characterization of the amount of power that could be supplied at the output of the harvesting antenna. The ray-based model is the approach selected for determining the incident power, and the three factors are added into a general transmitter-receiver model to approximate the incident power characteristics. A full simulation study is conducted, and it is found that the results obtained from the analytical analysis and simulations are in good agreement. The second part of the thesis is about developing a new bridgeless rectification circuit for an indoor Wi-Fi energy harvesting system. The proposed circuit is dedicated for impedance matching and voltage boosting for an indoor Wi-Fi energy harvesting system. The impedance matching is achieved by an LCL T-network in parallel with an inductive branch; such an arrangement can boost the input voltage level entering the rectifier diode by the combined effect of a T-network and bipolarity charging of the output capacitor. The return loss equation and an estimated value of matching circuit parameters are obtained analytically. There are three different modes for the voltage boosting process at two different input cycles. The power converting process is modelled, analysed, and relevant equations are derived. For simulation purposes, the dimension of the bridgeless rectifier circuit input port is designed using a co-planar waveguide arrangement where from the measurement, the impedance is 52.5 ??. Low return loss at 2.45 GHz is presented by proper circuit analysis and design. Practical measurement results based on an AC power source with an output impedance of 50 ?? also verified that the proposed circuit could function as an impedance matching and voltage boosting converter circuit with the aid of two additional low-voltage boost modules attached to the output of the bridgeless rectifier circuit as a load. It has demonstrated that the output voltage of the final energy buffering supercapacitor of 1800 ??F can be approximately charged up to around 3 V for about an hour when the input power of the AC source is set at -30 dBm (1 ??W). The third major part of this thesis is about a power processing circuit for an indoor Wi-Fi energy harvesting system. The complete power processing circuit is for an indoor energy harvesting system. The circuit is used to convert power from high-frequency AC to DC and stored in a supercapacitor bank for driving low power wireless sensors. The circuit is modelled using an equivalent circuit which is analysed mathematically. In the analysis, the need for matching the antenna and the rectifier input impedance is highlighted. The proposed circuit can work with an incident power as low as -50 dBm. The final RF to the dc conversion efficiency of the proposed system is consistently within 30% at -20 dBm input power. The practical results demonstrated that the efficiency of the harvesting system is higher than previous multi-band radio frequency energy harvesters. This research has created some outstanding methods and results for an indoor Wi-Fi radio frequency energy harvesting system, especially in approximating the incident power at a harvesting antenna, proposing a bridgeless rectification circuit, and developing a power processing circuit. The contribution will be useful for further research and application of the RF energy harvesting systems in the near future.

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  • Contact phenomena in the Serbian community in New Zealand: The language of the first-generation bilinguals

    Mincic-Obradovic, K (2017)

    Doctoral thesis
    The University of Auckland Library

    This thesis investigates the Serbian-English contact situation in New Zealand. It examines the language of 37 late bilinguals born in Serbia, who have been living in New Zealand for approximately ten to twenty years. Data for the analysis was collected in the 2004-2013 period, and comprises e-mail, text and Skype messages. Starting from Matras' (2009) functional approach, based on the view that language is a social activity and that communication is goal-driven, the study looks at the replication of English lexical matter items (MAT-replication) and their integration into Serbian, as well as at constructions which use Serbian lexemes but are modelled on English language patterns (PAT-replication). It investigates how the process of replication from English emerges in bilingual repertoires in New Zealand Serbian, and what factors contribute to this process. This study endorses Matras' argument that bilinguals, who have the repertoires of two languages at their disposal, exploit both of their languages, and make the most effective use of their full bilingual repertoire. This is particularly visible where lexical insertions are used consciously to achieve special conversational effects. Analysis shows that Serbian remains the pragmatically dominant language of first-generation Serbian immigrants in New Zealand, and supplies both the matrix and the morpho-syntactic frame. English is becoming stronger over time, and both MAT- and PAT-replications become more frequent. There is also an increase in innovations which are result of malfunctions in language selection, such as the borrowing of English-origin discourse markers, the loss of case markings in Serbian nouns, and failure to assign Serbian case markings to replicated English nouns. The study confirms that observed changes very much reflect creativity of individual participants, and that social factors have an important role in facilitating propagation of innovations in this bilingual community.

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  • Functional analysis of candidate flowering time genes from the model legume Medicago truncatula

    Che, Chong (2017)

    Doctoral thesis
    The University of Auckland Library

    Flowering at optimal times promotes the success of plant sexual reproduction and agronomic productivity and yield. Legumes are the second most important group of crop plants, but their flowering gene networks are less well understood than in the Brassicaceae and Poaceae. Medicago truncatula (Medicago) is a legume model plant with powerful genetic resources and which flowers in response to long day length and vernalisation (winter cold) conditions. A putative Medicago Polycomb Repressive Complex 2 (PRC2) subunit VERNALISATION2 (MtVRN2) was characterised previously in the Putterill laboratory, whose mutation led to early flowering. This indicated that MtVRN2 represses the transition to flowering in Medicago, opposite to VRN2 function in Arabidopsis thaliana (Arabidopsis). In addition, candidate floral integrator and homeotic genes had elevated expression in the Mtvrn2 mutant. An attempt was made to further characterise MtVRN2 function by analysing a candidate protein interactor CURLY LEAF (CLF, a candidate PRC2 member) using yeast two hybrid and pull down assays and selected candidate target genes (FLOWERING LOCUS Ta1, APETALA1, AGAMOUS-LIKE11 and SEPALLATA3b) using Chromatin Immunoprecipitation (ChIP)-PCR. In addition, a second candidate PRC2 member Medicago EMBRYONIC FLOWER2 (EMF2) was aimed to be functionally characterised. Third, the function of six candidate flowering genes related to SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) and FRUITFULL (FUL), some with elevated expression in the Mtvrn2 mutant, was examined by ectopic expression in Arabidopsis. The results of ChIP-PCR using transgenic Medicago plants overexpressing epitope HA-tagged MtVRN2 showed that MtVRN2 did not appear to bind directly to the selected candidate target genes. The protein interaction studies suggested that MtVRN2 might not physically interact with MtCLF via their VEFS and C5 domains respectively. The investigation of the cDNA clones of three MtEMF2-like genes revealed several different potential coding sequences from the annotated genomic sequence. Functional analysis revealed that MtEMF2 did not appear to play the same role as AtEMF2 in flowering time control. Three MtFUL genes and three MtSOC1 genes were identified in Medicago, as opposed to one of each in Arabidopsis. The overexpression of these six genes in Arabidopsis indicated the potential role of three of them, MtFULa, MtFULb and MtSOC1a in flowering time control because they accelerated Arabidopsis flowering.

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  • A Multi-scale Investigation of the Joint Tissue Response to Impact Induced Injury

    Workman, Joshua (2017)

    Doctoral thesis
    The University of Auckland Library

    A bovine patellae model of early osteoarthritis was used to investigate the multiscale response of articular cartilage to impact induced injury, and how this response differed in tissue showing early signs of degeneration. An impact testing rig was designed, constructed and validated. Following this, the mechanical response of articular cartilage with increasing levels of degeneration was investigated. The resultant reaction force from the cartilage decreased as the amount of degeneration present increased. The elasticity of the collision also decreased with level of degeneration, indicating that collisions with more degenerate cartilage lose more energy. It was determined that articular cartilage with only mild degeneration was more vulnerable to high levels of macro-scale damage than healthy tissue. There were no significant changes in mechanical properties during earlystage degeneration, but there are subtle structural changes such a decreased brillar interconnectivity which lead to a large increase in tissue vulnerability. In healthy articular cartilage, the matrix contains a highly interconnected network of collagen brils which are effective in halting the progression of fissures. In mild degeneration, there is a loss of transverse connectivity between brils, leading to a reduced crack arresting ability. These nano-level structural changes have a large influence on the propagation of fissures through the matrix, allowing them to travel through to the sub-chondral bone. In mildly degenerate articular cartilage the peri-cellular matrix is disrupted, reducing its ability to provide a mechanical transition between chondrocyte and surrounding matrix. This lead to ~260% more dead cells in mildly degenerate G1 cartilage after impact injury compared to healthy G0. In a linear regression model, the coeffcient of restitution, percent cell death and macroscopic Outerbridge level of degeneration were able to account for 94.5% of the variation in cartilage tissue vulnerability to impact damage. This research has contributed to a deeper understanding of the link between biologically mediated micro-anatomical and physiological changes, vulnerability to injury and potential initiation of post-traumatic osteoarthritis. The earliest stages of disease initiation cause the tissue to have a sharp increase in vulnerability to severe damage with a high possibility to hasten development of full depth osteoarthritis.

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  • Investigating the Climatic and Oceanographic Drivers of Spatial and Temporal Variation in Coastal Turbidity and Sedimentation

    Seers, Blake (2017)

    Doctoral thesis
    The University of Auckland Library

    Turbidity and sediment input in the coastal environment are greatly affected by human activities on land. Understanding the climatic, oceanographic and environmental drivers of temporal and spatial variability in coastal turbidity and sediment ux is key to understanding these processes and predicting how they may be affected by climate change. This thesis analysed monitoring data on coastal turbidity and sediment trap rates in the Hauraki Gulf to investigate how these spatio-temporal patterns relate to meteorological and oceanographic variables along an estuarine to open-coast gradient. These relationships were initially explored using a multivariate approach, and then quanti ed using a bayesian hierarchical framework with spline components. This model was developed along with two software packages to provide a predictive framework for analysing environmental monitoring data, with an emphasis on reproducibility and transparency. Turbidity declined along the estuarine to open-coast gradient. The primary driver of turbidity at the exposed open-coast regions was recent wave conditions that resuspend sediment, whereas tidal currents and daily rainfall are the primary drivers of turbidity at the harbour and estuarine sites respectively. The rate of fine sediment (< 63??) accumulation in traps was largely governed by processes that resuspend bottom sediments, primarily wind-generated waves and tides within harbour regions, and ocean swells on the open coast. Surprisingly, there was little to no relationship with rainfall suggesting that sediment traps should not be used to document terrestrial sediment introduction on subtidal reefs. The strong coupling found between meteorological and oceanographic factors, and coastal turbidity and sediment ux highlight a number of mechanisms whereby coastal turbidity will likely change as a result of climate change. Overall, turbidity is likely to decrease based on predictions of increased offshore winds and drier conditions throughout this region. However, more frequent and intense extreme weather events will likely result in unprecedented, transient increases in turbidity, creating a highly variable coastal turbidity environment. These effects on turbidity will likely be exacerbated by sea level rise and increasing coastal erosion, therefore improvements in land management practices and coastal protection are essential to offset the likely impacts of climate change on coastal turbidity.

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  • Autonomic reflex control of dominant pacemaker location and impulse propagation in the right atrium

    Ashton, Jesse (2016)

    Doctoral thesis
    The University of Auckland Library

    Reflex vagal control is a fundamental component of the autonomic regulation of heart rate, and loss of function in the vagal reflex arc is a negative prognostic indicator of cardiovascular health. Vagal activation can cause rapid and profound heart rate slowing and a concomitant caudal shift of the impulse origin within the sino-atrial node (SAN). The research presented in this thesis furthers our understanding of the mechanisms that contribute to pacemaker shift in the SAN. This advance has been accomplished through mapping impulse propagation in the right atrium (RA) during reflex activation with higher precision than previously achieved. For the first time, high-resolution extracellular and optical mapping techniques have been employed in a rat arterially perfused working heart-brainstem preparation (WHBP). Autonomic reflex pathways in the WHBP were kept intact, which enabled stimulation of the baroreceptor reflex under tightly controlled conditions, free of the confounding effects of anaesthetic agents on neural function. TheWHBP spontaneously produced eupneiclike phrenic nerve activity, characteristic of adequate oxygenation of the brainstem, and central cardiorespiratory coupling was preserved. The baroreflex was activated systematically by applying pressure challenges of increasing magnitude. Distinct dominant pacemaker (DP) regions with preferential conduction pathways were identified and related to the underlying distribution of cholinergic nerves fluorescently labelled using antibodies. There is a wide-spread notion that the DP is the SAN region with the highest intrinsic rate, and that ACh-induced pacemaker shift occurs when cells in the central node slow, allowing caudal pacemaker cells less sensitive to ACh to assume control at a higher rate. Our findings for the baroreflex onset are not consistent with this view. Baroreflex induced caudal DP shifts were synchronous with substantial increases in cycle length (CL). On the other hand, rostral pacemaker shifts during baroreflex recovery were coincident with small decreases in CL. We also observed competitive pacemaker activity between rostral and caudal regions immediately before DP shifts in recovery, but during onset only subthreshold depolarisation was detected in the rostral pacemaker region. Activation spread from caudal pacemaker sites through distinct conduction pathways to the crista terminalis (CT), but propagation toward the rostral SAN was slow. Taken together, these results are consistent with low safety factor for electrical propagation in the rostral SAN during baroreflex and suggest caudal DP shift occurs as a result of failure of central pacemaker cells to drive activation in surrounding myocardium. To probe this mechanism further, we compared baroreflex results to responses recorded during stimulation of peripheral chemoreceptors with arterial injection of KCN and homogeneous stimulation of muscarinic (M2) receptors with an arterial bolus of carbachol (CCh). The dynamics of DP shift during onset and recovery of chemoreflex activation were comparable to that recorded during baroreflex responses, but larger fluctuations in CL and DP shifts were seen in synchrony with inspiratory motor drive, consistent with enhanced respiratory coupling as a result of the hypoxic stimulus. Compared to baroreflex and chemoreflex responses, CCh induced more gradual changes in CL, and DP shifts during onset and recovery occurred with small changes in CL that were not significantly different. This result led us to hypothesise that the speed of onset of cholinergic stimulation is an important factor in determining whether DP shift occurs due to failure of impulse propagation from the central SAN. To test this hypothesis, we explored changes in the dynamics of DP shift following inhibition of If with the HCN-channel specific blocker ivabradine (IVB). Post-IVB, baseline CL increased on average by ???19%, indicating effective If inhibition in the SAN. The onset of CL responses to reflex and CCh stimulation was faster post-IVB, with a shorter time to maximum CL. There was a trend toward larger increases in CL with DP shifts during onset and recovery but this was not significant over all stimulation methods. The trend was most evident for CCh responses, where the range of CL increases with DP shift was augmented. In some reflex responses, the increase in CL was attenuated post-IVB and caudal DP shifts did not occur or occurred with small changes in CL later in the response, suggesting IVB could have altered reflex function. Here, our findings show If acts to buffer the rate slowing effects of cholinergic stimulation and thereby modulates the timing of DP shift during periods of increasing CL. Lastly, we attempted to develop a toxic cardiomyopathy model of atrial structural remodelling in order to assess the effects of SAN fibrosis on reflex control of pacemaker function in the WHBP. We delivered single isoprenaline injections on two consecutive days across a dosage range from 150 to 340 mg kg???1. In vivo cardiac cine-MRI demonstrated a slightly lower left ventricular (LV) ejection fraction at 340 mg kg???1 compared to control (66% vs. 71%), and less contraction of the LV lumen at end systole. Measurements of LV pressure at this dose showed an elevation of mean change in diastolic pressure compared to control (9.58 vs. 3.54 mmHg). Picrosirius red staining of collagen in LV tissue sections showed patchy interstitial fibrosis which was not present on sections from control samples. Our results are consistent with the development of ventricular dysfunction and structural remodelling after isoprenaline injection, but the very low mortality rate observed (5%) suggests the effects of isoprenaline in the juvenile rats used here are more moderate than those reported for adult rats. In conclusion, we have completed the first high-resolution analysis of SAN function during vagal reflex activity in a strictly controlled preparation with intact autonomic reflex pathways. Our most novel finding is that reflex-induced caudal DP shift is not driven by rate entrainment alone and appears instead to be the result of failure of impulse propagation from the central SAN. We hypothesise that the DP is therefore the region with the highest intrinsic rate in the SAN that has the capacity to drive electrical activity in the surrounding atrial myocardium.

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  • HbA1c as a marker of prediabetes: a reliable screening tool or not?

    Sequeira, Ivana; Poppitt, Sally (2017-04-03)

    Journal article
    The University of Auckland Library

    Increasing global prevalence of type 2 diabetes (T2D) has resulted in concerted efforts to improve predictors for development of this obesity-related disorder. Establishing markers that identify prediabetes, an intermediary state of glycaemia above that of healthy individuals but below frank T2D, is an important focus. International cut offs have long been based on the 2 h WHO-defined oral glucose tolerance test (OGTT), but more recent use of the quicker and cheaper marker of glycated haemoglobin (HbA1c) has become widespread in clinical practice and public health. The definition of people with prediabetes in turn has expanded from those with impaired glucose tolerance (IGT) to include individuals with impaired fasting glucose (IFG) and/or raised HbA1c. Whilst HbA1c has been recommended since 2010 for both T2D and prediabetes screening, concerns have been raised over validity particularly for identifying those who will later develop T2D. Depending on criteria, HbA1c may identify only 50% with abnormal OGTT or misclassify those with normal physiology. Models predicting average time intervals for progression to T2D from prediabetes are commonly limited by ethnic, racial and gender differences, and different criteria further result in variable estimates of prediabetes prevalence and impact those eligible for lifestyle interventions. Whilst HbA1c may provide a good marker of frank T2D, some recommend its use in prediabetes only in conjunction with fasting plasma glucose (FPG). This review updates current opinion on HbA1c as an effective screening method for categorising high-risk prediabetic individuals and those requiring fast track into lifestyle modification programs.

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  • Kicking at the Habitus: Exploring staff and student ???readings??? of a socially critical physical education teacher education (PETE) programme

    Philpot, Roderick (2016)

    Doctoral thesis
    The University of Auckland Library

    While social justice and equity are themes foregrounded in many initial teacher education (ITE) programmes, there are a myriad of ways in which ITE draws attention to inequities and supports future teachers with the skills, knowledge and desire to address these issues. Critical pedagogy, with roots steeped in critical theory and the emancipatory literature of Paulo Freire is an orientation to ITE that privileges such aims. This thesis examines how critical pedagogy is understood and enacted by physical education teacher education (PETE) teacher educators in a single PETE programme that is underpinned by a critical orientation, and also the sense that the students in the programme have made of the critical pedagogies they encounter. At one level this thesis is an attempt to understand the enactment and subsequent reading of critical approaches to PETE. At a deeper level this research has the emancipatory aims of producing physical education (PE) teachers who aspire to, and who are equipped with, the required skills and dispositions for foregrounding social justice in their own teaching. In this thesis I draw on critical theory, specifically the work of Paulo Freire, Jurgen Habermas and Pierre Bourdieu, to illustrate both the synergy and tensions associated with the enactment of critical pedagogies by several teacher educators who teach within a single ITE programme. The teacher educators??? varying understandings and subsequent enactments of critical pedagogy ensure that their students are exposed to numerous critical approaches. At the same time, the encounters between individual student biographies and multiple, often unique, critical approaches, have led to uncertainty within students in their ability to coherently explain what critical pedagogy is, and how they could teach from a critical perspective. Each student claims that critical approaches in the PETE programme have made a difference, yet it is a different difference for each student. Complex life histories have served to filter the sense that students have made of the PETE programme. Some students understand critical pedagogy as taking action against structural injustices. These students have the eyes to recognise, and the will to address, some issues of social inequity, most often those issues they have encountered through their own lives. Other students conceive of critical pedagogy as a process of problematising knowledge and reflecting on their own teaching.

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  • Human gastric slow wave activity redefined through high-resolution mapping

    Berry, Rachel (2016)

    Doctoral thesis
    The University of Auckland Library

    Gastric contractions are initiated, propagated and coordinated by underlying rhythmic bioelectrical potentials termed slow waves. Slow waves propagate through the musculature via conduction networks comprised of specialised cells, and act in combination with the enteric nervous system to regulate peristalsis. Disordered slow wave activity has been associated with the pathophysiology of several motility disorders, and occurs as a result of the abnormal function of, or disruption to these specialised cells and their distribution pathways. This thesis aimed to: i) define regional variations in slow wave characteristics in the distal stomach, identified during previous high resolution (HR) mapping research, ii) explore the consequences of disruption to the bioelectrical conduction pathways and removal of the primary gastric pacemaker, and iii) develop new laparoscopic recording arrays with a view to increasing coverage and accuracy of slow wave mapping. The investigation of slow wave characteristics in the distal stomach was performed using HR mapping techniques and flexible printed circuit (FPC) electrode arrays. The arrays were positioned on the antrum and used to detect significant increases in the velocity (3.3 ?? 0.1 mm s-1 vs 7.5 ?? 0.6 mm s-1; p0.05) and amplitude (1.7 ?? 0.2 vs 1.6 ?? 0.6 mV; p>=0.05) of slow wave cycles was unaffected, however velocity increased significantly (3.8 ?? 0.8 vs 12.5 ?? 0.8 mm s-1; p=0.01) following surgery. These data show that primary pacemaker removal and disruption of slow wave conduction networks causes dysrhythmic activation and propagation patterns. These may resolve naturally or potentially lead to the development of gastric motility disorders. HR mapping of a previous LSG patient reporting ongoing pain, acid reflux and food intolerance 15-months postoperatively revealed a persistent ectopic pacemaker in the antral region of the sleeve. Slow waves were found to consistently propagate around an area conduction block, and were of a higher velocity (12.6 ?? 4.8 mm s-1) than anticipated. However, frequency (2.2 ?? 0.01 cpm) and amplitude (2.3 ?? 1.9 mV) were within normal ranges. The results suggest that pain, reflux and food intolerance following LSG may be associated with a deviation from normal bioelectrical activity patterns occurring following removal of the gastric pacemaker. The increasing adoption of minimally invasive procedures for the treatment of gastrointestinal (GI) diseases prompted the development of a laparoscopic device capable of recording slow wave activity directly from the serosal surface of the target organ. This device improved on previous designs with a larger coverage area and a greater number of electrodes; a larger field of electrodes is particularly relevant when attempting to characterise dysrhythmias, and reduce error when calculating the direction and velocity of slow waves. Simultaneous recordings from the improved design and a FPC array in pigs were identical in frequency (2.6 cpm; p>0.05). Activation patterns and velocities were also consistent (8.9 ?? 0.2 vs 8.7 ?? 0.1 mm s-1; p>0.05). Device and reference amplitudes were comparable (1.3 ?? 0.1 vs 1.4 ?? 0.1 mV; p>0.05), although the device signal to noise ratio (SNR) was higher (17.5 ?? 0.6 vs 12.8 ?? 0.6 dB; p<0.01). Slow wave activity was also recorded and mapped from the corpus of a human patient and was within the known physiological range for human gastric slow waves (frequency 2.7 ?? 0.03 cpm), amplitude 0.8 ?? 0.4 mV, velocity 2.3 ?? 0.9 mm s-1). The laparoscopic device achieved high-quality gastric serosal slow wave recordings and demonstrated its potential for documenting slow wave characteristics in patients with gastric dysmotility disorders. The work within this thesis presents a series of advances that enhance our investigation and understanding of gastric slow waves. It is anticipated that these novel mapping tools, combined with improved knowledge of both normal and dysrhythmic activity will progress clinical diagnoses and patient treatment options.

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  • Site-specific effects of loading on the osteochondral tissues of the equine distal metacarpus

    Turley, Sean (2016)

    Doctoral thesis
    The University of Auckland Library

    The distal end of the third metacarpal bone is among the most highly loaded sites in the equine appendicular skeleton, and a common site of injury and degeneration. The objective of this thesis was to investigate site-specific changes in the microstructure and mechanical properties of the osteochondral tissues of the distal third metacarpal in response to in vivo loading, and how such changes may precede lesion development in the palmar region. Osteochondral tissue changes were evaluated in terms of mechanical and morphological parameters, including in athletically trained horses. Mechanical testing included indentation testing to determine cartilage modulus, and impact testing. Tissue morphology was assessed using bright field microscopy and differential interference contrast microscopy to view thick osteochondral sections in a full hydrated state. Regions of higher in vivo loading were associated with thinner calcified cartilage, reduced cartilage mechanical properties, and greater cement line rugosity and subchondral bone volume fraction. High subchondral bone volume fraction, high cement line rugosity, and reduced cartilage mechanical properties were identified as possible precursors of degenerative change in the articular cartilage of the palmar region. The progression of repetitive overload-induced lesions in the palmar aspect of the third metacarpal of Thoroughbred racehorses was documented from initial microcrack formation through to severe subchondral bone collapse. Extensive levels of microdamage were frequently concealed beneath outwardly intact hyaline cartilage. Notably, fibrous repair tissue was found at the articular surface in cases where subsidence of the subchondral bone had occurred, suggesting a repair response aimed at maintaining articular surface congruity. However, there was some evidence to suggest that this repair tissue was vulnerable to mechanical disruption when exposed to continued loading. This thesis makes a contribution to the literature by: (i) Providing detailed information on site-specific adaptations in osteochondral morphology and mechanical properties in relation to load, including in athletically trained animals; (ii) Identifying osteochondral changes that may predispose towards degeneration; (iii) Documenting the morphological progression of damage accumulation and lesion development in the palmar aspect of racing Thoroughbreds; and (iv) Presenting detailed images of the aforementioned lesions in the full context of the joint tissue complex, spanning from the articular surface to the subchondral bone.

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  • Childhood outcomes in children at risk of neonatal hypoglycaemia

    Burakevych, Nataliia (2016)

    Doctoral thesis
    The University of Auckland Library

    Aim The aims of this thesis are to (1) describe growth and neurodevelopmental outcomes of children born at risk of neonatal hypoglycaemia, a common condition that may be associated with adverse neurodevelopmental outcome; (2) investigate methods used for data collection in paediatric longitudinal studies; and (3) determine the relationships between glycaemic response to neonatal hypoglycaemia, its treatment, and later neurodevelopmental outcome. Methods Prospective study of children born at risk of neonatal hypoglycaemia at Waikato hospital (2006-2010), the CHYLD study. Intermittent blood and continuous interstitial glucose concentrations were recorded in the neonatal period. Hypoglycaemia (blood glucose concentration <2.6 mmol/l) was treated with breast milk, formula, dextrose gel, and intravenous dextrose. At 2 and 4.5 years??? corrected age children were assessed for neurodevelopmental and general health status. Caregivers completed questionnaires about the medical history and social-emotional health of their children. Children???s hospital records were accessed and preschool screening data was obtained from the Before School Check programme. Findings Children in our study lived in more deprived areas compared to the national average, and approximately a third had neurosensory impairment at both 2 and 4.5 years. Neurodevelopmental outcomes were not related to neonatal risk factors. We identified problems with several of the methods commonly used for follow-up assessments. Caregivers could not accurately recall previous hospital admissions at the 4.5 year assessment when compared to hospital records. Referral criteria for developmental and emotional health problems were not applied consistently in the Before School Check, and children who had problems often missed out on screening. In addition, assessment of motor function at 2 years was not predictive of motor difficulties at 4.5 years. We found that treatment of neonatal hypoglycaemia was associated with different glycaemic responses in the six hour period after hypoglycaemia, and the rate of change in glucose concentrations was related to later neurodevelopmental outcome. Conclusions Our findings in an at-risk cohort of children with high impairment rates will help researchers and clinicians to plan future studies, draw attention to some limitations of the New Zealand preschool screening programme, and guide future research on treatment of neonatal hypoglycaemia to improve later outcomes.

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  • Volumetric characterisation of contracting cardiac trabeculae

    Cheuk, Ming (2017)

    Doctoral thesis
    The University of Auckland Library

    Experimental studies performed on isolated cardiac muscle are crucial for understanding the mechanisms of heart contraction. Not only do they reveal the sub-cellular processes that occur during a normal contraction, but also the changes that occur with disease. An understanding of these processes is crucial for the prevention and treatment of heart diseases. Experimental studies are usually performed on samples of different shapes and sizes, requiring that volume dependent measurements such as force and heat-rate be normalised to crosssectional area or volume in order to compare data between samples. However, many research groups are limited to estimating the shape and size of trabeculae by assuming an elliptic cylindrical geometry of the muscle. This simplification falls short when the cross sections of the muscle cannot be appropriately modelled by an ellipse. The accuracy also varies considerably depending on how the muscle is mounted. This thesis addresses the problem of normalisation by using optical coherence tomography (OCT) to image the 3D volume of the trabecula during an experiment, and by quantifying the cross-sectional areas and volume of the tissue using an image processing pipeline. An additional challenge arises from the non-uniform strain commonly developed during contraction, which is accompanied by irregular deformation of the volume. To measure this deformation, the OCT was extended to image a contracting trabecula, by synchronising the capture of cross-sectional images with the stimulation of the muscle. This approach allowed the collection of the first volumetric quantification of trabecular surface geometry during contraction. To further analyse the strain field developed during contraction, transmission images of the muscle were captured, and muscle deformation quantified using digital image correlation (DIC). Measurements of volume and strain during contraction were combined with measurements of force, length, heat-rate, and sarcomere length in a single experiment in order to demonstrate the ability to collect and synchronise measurements across all modalities. The instrumentation and analysis methods developed in this thesis promise to provide greater insight into the mechanical and energetic properties and function of living samples of cardiac muscle tissue, in both health and disease.

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  • Flow condensation of CO2 in a horizontal tube at low temperatures

    Li, P (2016)

    Doctoral thesis
    The University of Auckland Library

    Carbon dioxide (CO2) has been recognised as a low-cost, high efficiency and non-toxic natural refrigerant suitable as a substitution for CFCs and HCFCs in the low-temperature circuits of cascade or volatile secondary refrigeration systems. Due to the unique thermophysical properties of CO2 when working in the high reduced pressure conditions of these systems, existing correlations fail to predict flow condensation heat transfer rates accurately, and new models need to be developed for the design and optimisation of CO2 condensers. An experimental study was conducted to measure the heat transfer rate of CO2 flow condensation for mass fluxes ranging from 100 to 500kg/m2-s, at saturation temperatures of -10, -5 and 0??C under a wide range of vapour qualities inside a horizontal 4.73mm inner diameter tube. An open-loop test rig was used which featured a high stability of the coolant temperature. Experimental results showed that the effects of mass flux and vapour quality on the rate of heat transfer were more significant in annular flows than in stratified flows, and that high mass fluxes and vapour qualities resulted in high heat transfer rates. Experimental results also showed that decreasing the saturation temperature significantly increased the heat transfer rate in annular flows compared to flow condensation in stratified flows. A new model for CO2 flow condensation inside horizontal tubes was proposed which included criteria for flow regime transition and empirical correlations to predict the heat transfer rate in each regime. The transition was predicted by Soliman???s Froude number which was fitted to the published experimental observations of transition between CO2 two-phase flow regimes. Two semi-analytical correlations were fitted to the experimental data, one for annular and the other for stratified flows. The proposed model was evaluated against a CO2 flow condensation databank, which included the heat transfer measurement points from references in the open literature and the present experimental study. Comparison results showed the current model successfully predicted the data points with an average absolute deviation of 7%.

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  • Rethinking the Philosophical Approach to Higher Education in Ghana

    Amuzu, Delali (2017)

    Doctoral thesis
    The University of Auckland Library

    This study investigates how higher education [H.E] at a university level in Ghana can serve a public purpose (the common good of society). The study uses a qualitative mode of inquiry with a critical studies approach. It further utilises autobiography to investigate what it means to be educated in Ghana ??? this approach locates the researcher in the study. An extended literature review is utilised to illustrate the main features of historical development of H.E in Ghana. Semi-structured interviews were employed to help gather empirical data in order to answer questions as to how H.E in Ghana is elitist; the alternative means of funding H.E in Ghana; and the possible future of H.E in Ghana. Given that the framework of Ghana???s H.E is a legacy of the British colonial heritage, broad based anti-colonial persuasions of Franz Fanon, Kwame Nkrumah, Aim?? C??saire, Leopold Sedar Senghor and Marcus Garvey were utilised. Specifically, the anti-colonial theorisation by Simmons and Dei (2012), which draws from the works of the above-mentioned theorists was adopted as a framework to argue that Western notions of H.E dislocate the highly schooled Ghanaian historically, spiritually, aesthetically, socio-politically and ethically. The thesis finds that the basis for conceptualising an ???educated??? person in Ghana is the acquisition of European values and outlooks. Further, whereas the main feature of traditional African H.E focuses on the cultivation of ethical values to nurture character in order to enhance a person???s humanity, the greater possibilities for employability is the main concentration of Ghanaian universities. Even though the extent of elitism in Ghanaian universities has reduced, the pre-eminence given to Western worldviews and perspectives and the restricted access to medical sciences and business programmes remain strands of elitism. The study reveals the need for universities to generate useable knowledge through a connection between H.E institutions and society to enhance the prospects of funding. The future possibilities of H.E are both bleak and bright depending on the trajectory universities adopt. Overall, the findings suggest that for H.E to serve a public purpose in Ghana, it must be localised and based on Ghanaian/African epistemological, ontological and axiological worldviews.

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  • Chemoattraction in New Zealand scampi (Metanephrops challengeri): Identifying effective baits to develop a potting fishery

    Major, Robert (2017)

    Doctoral thesis
    The University of Auckland Library

    New Zealand scampi (Metanephrops challengeri) is a commercially important deep-water lobster species that is caught by bottom trawling on areas of muddy seafloor on the continental shelf below 300 m in areas around New Zealand. Bottom trawling is a fishing method that typically produces high levels of bycatch and is associated with extensive benthic habitat damage. Pots (also known as creels or traps) tend to have a lower environmental impact when used as an alternative harvesting method to trawling in a number of crustacean fisheries, and may have potential application for scampi. A key component of pot fisheries are effective and economic baits. Therefore, the aim of the research presented in this thesis was to identify effective baits for a scampi potting fishery, by firstly understanding the chemically-mediated food search behaviour of scampi. To achieve this aim the research followed a framework previously identified in the literature;1) characterising the phases of food search behaviour of scampi (presented in Chapter 2); 2) investigating the effect of different hydrodynamic regimes on this behaviour (presented in Chapter 3), and 3) utilising a binary-choice flume to compare the attractiveness of different potential baits (presented in Chapter 4). Additionally, a field experiment was undertaken to assess how baits influenced the operation of pots targeting scampi, especially in terms of their interaction with pot design and the resulting bycatch (presented in Chapter 5). The results of the research showed that the time scampi spent during each of the phases of chemically-mediated food search behaviour was highly variable regardless of the bait tested. However, scampi are more efficient at searching for food in turbulent versus laminar flow conditions. The New Zealand pilchard (Sardinops neopilchardus) baits were identified as being more attractive to the scampi than a number of alternative natural seafood baits. Homogenised pilchard tissue that was diluted (1 & 10% by wet weight) and set in an alginate binder were as attractive to scampi as both the natural pilchard tissue and a positive control to which scampi have previously been conditioned to respond to. This suggests that artificial baits utilising diluted fish tissue may be a practical approach for reducing the amount of fish that would be required for baits in developing a potting fishery for scampi. The advances in the understanding of scampi behaviour made by this research highlight that scampi are likely to feed on a range of food items, and are likely to be more efficient searching for food during periods of higher tidal flow associated with greater turbulence near the seafloor. The results of the potting study showed that the type of bait used did not affect the quantity of composition of the bycatch caught in pots, and that bycatch can be reduced in pots through appropriate pot design and spatially targeted fishing. Overall the results of this research provide a valuable foundation for advancing the potential for developing a more environmentally benign potting fishery for New Zealand scampi.

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  • 3D printed conducting polymer microstructures as an ultra-low velocity flow sensor

    Devaraj, Harish (2016)

    Doctoral thesis
    The University of Auckland Library

    To develop devices for improving the quality of life such as handheld electronics, artificial muscles, lab-on-chip devices, etc., the quest for future smart materials has led to increasing interest in Conducting Polymers (CPs). Recent technological advancements have already exploited the many advantages of CPs, but to further their usability, we require a reliable and robust means of fabricating CPs at micrometric scales. This research work focusses on demonstrating these fabricated CP micro-structures??? applicability in biomedical applications and, more specifically, as a means of sensing and measuring air flow levels observed during neonatal resuscitation. In this thesis, I present a reliable means of fabricating three-dimensional CP microstructures, in particular focusing on fabricating hair-like microstructures from Poly(3,4-ethylenedioxythiophene) Poly(styrene sulfonate), referred to as PEDOT:PSS. A 3D printer was developed with capabilities of producing microscopic patterns and structures using miniaturized pipettes for dispensing the CP material. A Graphical user interface was also developed to allow human interface with the microstructure printer. A novel flow sensor prototype was developed using PEDOT:PSS micro-hairs, where these micro-hairs act as microscopic switches which open and close in response to air flow. By using an array of micro-hairs that respond to specific flow velocities, a discrete digital output flow sensor was demonstrated. A means of improving the sensitivity of the flow sensor to lower flow velocities was also demonstrated by printing the micro-hairs within a narrow convergent-divergent flow channel. To improve the understanding of the flow sensor???s response to air flow by simulating the Fluid-structure interactions (FSI), a robust mathematical model was developed. Based on Lattice Boltzmann equations for simulating the fluid flow in a 3D domain and beam theory for simulating large deflections, the model was exclusively coded in MATLAB. Using dimensional transformations to minimize the computational costs, a mixed 2D and 3D simulation for the developed FSI model is presented. Using the FSI model, a final sensor prototype was developed specifically to be compatible with the target neonatal resuscitator device. Apart from being capable of measuring the ultra-low velocity flows experienced during neo-natal resuscitation to meet the demands of the target application, this prototype sensor was designed to be portable with the capability of reading out flow levels directly integrated with the sensor. Furthermore, the portable sensor was also developed with a disposable architecture to improve medical compatibility. By successfully demonstrating the capabilities of fabricating CPs in micrometric scales and using these microstructures as a suitable means of sensing air flow through the development of an ultra-low velocity flow sensor, the suitability of using CP microstructures in real world applications has been demonstrated.

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  • What happens at work goes home: Investigating secondary traumatic stress and social support among the partners of New Zealand's Police, Fire, Ambulance and Defence Personnel

    Alrutz, Anna Stowe (2017)

    Doctoral thesis
    The University of Auckland Library

    Police, fire, ambulance and defence force personnel (responders) risk experiencing dangerous activities, traumatic events and the development of post-traumatic stress disorder. In turn, spouses/partners (partners) of these responders risk developing secondary traumatic stress (STS) as they are exposed vicariously to the trauma through communication with their responders. The research aimed to address the question: How do the partners of NZ defence and emergency responders respond to work stress experienced by their responder? The study used six research questions and six hypotheses to identify resources and barriers towards effective management of STS. A mixed methods approach assessed the experience of STS among the partners of New Zealand???s (NZ) responders. Using this approach the researchers interviewed participants prior to survey data collection and again after the survey to facilitate interpretation and incorporate feedback. After pilot-testing, the anonymous online survey was made available nationwide. The survey measured STS in partners, perceived stigma towards help-seeking, partner resilience and relationship satisfaction. The survey asked if the defence and emergency responder???s organisation invited partners to events, offered inductions, or offered informational resources to manage stress. Partners were asked who they turned to when dealing with stressful situations experienced by their responder. The survey concluded with open-ended questions about organisational engagement with the partners and responders. Themes were identified from analysis of the qualitative responses given by the 835 partners of NZ responders. A hypothesised model was produced and tested using multiple regression (n=664) which led to the creation of a structural equation model (SEM) (n=547) to describe interactions between resources and barriers. The study found that 20???35% of partners experience significant symptoms of STS and almost half feel unsupported when managing stressful issues experienced by their responders. Positive organisational communication benefits partners and reduces psychosocial risks. The thematic analyses endorsed increasing partner self-efficacy and encourages organisations to identify partner accessible resources. Triangulating the results obtained from these mixed methods highlights challenges faced by partners of defence and emergency responders and suggest how direct organisational engagement with the partners of their employees could reduce risks associated with secondary exposure to trauma.

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  • Gendered Academic Careers: A Comparison of Indonesia and New Zealand

    Toyibah, Dzuriyatun (2017)

    Doctoral thesis
    The University of Auckland Library

    This thesis aims to describe and better understand the gender gap in academic careers in Jakarta (Indonesia) and Auckland (New Zealand). The thesis is intended to measure and explain the operation of the gender gap, while also interrogating the construction of such indices as essentially Western in their assumptions. For example, The Global Gender Gap Report (World Economic Forum, 2015), rates New Zealand 10/145 and Indonesia, 92/145 of countries surveyed. A review of the global rankings shows a patterning of Western and non-Western countries and clearly invites deficit-based explanations in terms of development, culture, religion. As an Indonesian woman, such patterning also invites unease and disquiet. While I have experienced the everyday processes that produce the gender gap in academia and societally, I am also aware of the complexities and countervailing elements that reports like The Global Gender Gap Report might miss. One result of unease with a simple notion of the gender gap index, is to enrich research through the use of mixed methods, combining qualitative and quantitative approaches. This thesis explores and contextualises issues around the gender gap in academic careers, by using mixed methods across institutional cases based in Jakarta and Auckland. The methods used include: (i) secondary research, including analysis of promotion policies; (ii) an autoethnographic account, in which I discuss issues of gender, marriage, religion, patriarchy, motherhood, class, and social status; (iii) a quantitative analysis of differing datasets drawn from Indonesian and New Zealand institutions, using descriptive statistics, binary and ordinal regression; (iv) the non-comparability of datasets and of quantitative analysis reinforced my decision to include qualitative approaches in the mix of methods. Accordingly, I interviewed 30 academics in Auckland and Jakarta. The main findings of the research are: (i) It confirms the literature that male domination in academia is hidden and female academics who are mothers are marginalised. For academics who are also mothers, there is a collective understanding that the barriers are significant; (ii) Racial discrimination exists, but is largely invisible. Participants of colour acknowledged it and indeed had experienced it, though other participants, in the same universities, believed that it no longer occurred. Arguably, gender and race are rendered invisible in academic careers under a neo-liberal system, especially when using statistical analysis, as such elements are considered non-meritocratic factors; (iii) Understanding the academic gender gap in Indonesia is better framed by considering the fact that career progression follows civil servant regulation, and is not perceived as very prestigious in terms of income. Rather, being an academic, according to some Indonesian academics, is about a ???calling??? and devotion to knowledge development; (iv) On the other hand, studies in liberal, Western countries emphasise that family life, children, and domestic work are serious problems for female academics. To be single or childfree is considered to enhancefemale academic careeradvancement. In conclusion, comparing the scale of the gender gap index between liberal countries such as New Zealand and non-liberal countries such as Indonesia is very challenging due to cultural and structural differences. My research underscores that it is important to measure women???s conditions beside indicators developed in the Gender Gap Index (economic participation and opportunity, educational attainment, health and survival and political empowerment). It is necessary to include indicators which are accepted in all cultures and nations, such as the index of happiness, life satisfaction; indicators must align with desires and hopes for the future. Critique is essential to create the conditions for transformative change but that change should align with individual and collective aspirations.

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  • Review of: Conny Kristel, De Oorlog van Anderen. Nederlanders en Oorlogsgeweld, 1914 - 1918. Amsterdam, De Bezige Bij, 2016

    Abbenhuis, Maartje (2017-03)

    Journal article
    The University of Auckland Library

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  • The Microbiology of Septic Arthritis in Young Auckland Children

    Boom, MVD; Webb, Rachel; Lennon, DR; Crawford, H; Freeman, J; Castle, J; Mistry, R (2016-12-01)

    Conference item
    The University of Auckland Library

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