12,115 results for 2000, University of Canterbury Library

  • Generation and structural characterisation of transient gaseous species.

    Atkinson, Sandra Jane (2015)

    Doctoral thesis
    University of Canterbury Library

    Gas electron diffraction (GED) is a technique that has been developed to study the molecular structure of species in the gas phase. This thesis focuses on the reconstruction of the Canterbury GED apparatus (moved from Edinburgh, UK) and the requirements for modifying the apparatus to incorporate a mass spectrometer (MS) so diffraction and MS data can be obtained within a single experiment. The combined GED-MS system has been identified in previous work in the Masters group as a necessary development for studying the structure of short-lived species generated in situ. This is particularly true for the study of ketene, which as shown in this thesis, can be generated from several precursors as part of a multiple product pyrolysis system. While GED data for ketene generated from acetic anhydride has been refined, the species formed from the pyrolysis of Meldrum’s acid were determined to be too difficult to deconvolute without additional experimental data from MS. A computational study of possible ketene derivatives that could be studied with a GED-MS apparatus is also presented. Lastly, this thesis details a structural study of the gas-phase structures of tris(chloromethyl)amine and a family of substituted disilane systems which have been determined in the gas phase for the first time. A comprehensive GED, Raman spectroscopy and ab initio study have been undertaken for tris(chloromethyl)amine [N(CH2Cl)3] which is shown to have a different structure in the solid and gas phase. Further work in the form of a molecular dynamics investigation has been identified as necessary to describe the low amplitude motion of one of the CH2Cl groups in the gas phase to allow for the GED refinement to be completed. The work on the substituted disilane systems X3SiSiXMe2 (X = F, Cl, Br, I) and X3SiSiMe3 (X = H, F, Cl, Br) demonstrates the effect of increased halogen substitution on the electronic effects of the disilanes, and the effect that the methyl groups have as larger halogens increase the steric bulk of the system.  

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  • A Study on the Usability of Hand-Held and Wearable Head-Mounted Displays in Clinical Ward Rounds.

    Yakubu, Muhammad Nda (2015)

    Masters thesis
    University of Canterbury Library

    In this thesis research, we investigate the usability of hand-held display (Tablet PC) and wearable head-mounted display (Google Glass) interfaces and their effect on doctor-patient interaction during clinical ward round in the hospital. We looked at existing literature to identify existing research about our topic. Using a User Centered Interaction Design process we developed a prototype hybrid system that used both a hand-held and head-mounted display. An evaluation of this prototype with a hand-held system and a paper based interface was performed in a simulated patient room with 20 doctors and 5 patients. The participants were observed, surveyed, and interviewed about their experiences. Generally, the patients had a high satisfaction rate and felt the interfaces were not causing the doctors to lose focus on them. The doctors found the hand-held display by itself and existing paper-based interface to be the most usable and least distracting interfaces for accessing patient information during clinical ward rounds.

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  • Preparation of monolayer tethers via reduction of aryldiazonium salts.

    Lee, Lita (2015)

    Doctoral thesis
    University of Canterbury Library

    This thesis describes the preparation of surface-attached monolayer tethers from electroreduction of aryldiazonium ions using a protection-deprotection strategy. Monolayers of ethynylphenyl, carboxyphenyl, aminophenyl and aminomethylphenyl were prepared. Glassy carbon (GC) and pyrolysed photoresist film (PPF) surfaces were modified electrochemically and characterised by redox probe voltammetry. The monolayer tethers were coupled with electro-active ferrocenyl (Fc) and nitrophenyl (NP) groups for the indirect electrochemical estimation of the surface concentration. Film thickness measurement was carried out using an atomic force microscopy (AFM) depth profiling technique. The surface concentration and film thickness measurement results were consistent with the formation of monolayer films after removal of the protecting groups. Preparation of mixed monolayers was studied using three different modification strategies: i) grafting from a solution containing two different protected aryldiazonium ions, ii) sequential grafting of two different protected aryldiazonium ions, and iii) grafting of protected aryldiazonium ions followed by removal of the protecting group and reaction of an amine or carboxylic acid derivative directly with the GC surface. The composition of the mixed layer prepared using the first method is difficult to control, whereas the possibility of multilayer formation cannot be discounted using the second method. Multilayer formation is unlikely using the third method. The electrocatalysis of oxygen reduction at mixed monolayer films was investigated briefly. The origin of the two reduction peaks frequently observed for electroreduction of aryldiazonium ions at carbon surfaces was studied. Electroreduction was carried out at GC and HOPG surfaces. The reduction peak at the more positive potential is surface sensitive, while the peak at the more negative potential is not. However, both reduction peaks lead to deposition of films and it is tentatively proposed that the more positive peak corresponds to reduction at a ‘clean’ GC electrode, and the more negative peak corresponds to reduction at the already grafted layer.

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  • Analysis, development and management of glucose-insulin regulatory system for out of hospital cardiac arrest (ohca) patients, treated with hypothermia.

    Sah Pri, Azurahisham (2015)

    Doctoral thesis
    University of Canterbury Library

    Hyperglycaemia is prevalent in critical care and increases the risks of further complications and mortality. Glycaemic control has shown benefits in reducing mortality. However, due in parts to excessive metabolic variability, many studies have found it difficult to reproduce these results. Out-of-Hospital Cardiac Arrest (OHCA) patients have low survival rates and often experience hyperglycaemia. However, these patients belongs to one group who has shown benefit from accurate glycaemic control (AGC), but can be highly insulin resistant and variable, particularly on the first two days of stay. Hypothermia is often used to treat post-cardiac arrest patients or out of hospital cardiac arrest (OHCA) and these same patients often simultaneously receive insulin. In general, it leads to a lowering of metabolic rate that induces changes in energy metabolism. However, its impact on metabolism and insulin resistance in critical illness is unknown, although one of the adverse events associated with hypothermic therapy is a decrease in insulin sensitivity and insulin secretion. However, this decrease may not be notable in the cohort that is already highly resistant and variable. Hence, understanding metabolic evolution and variability would enable safer and more accurate glycaemic control using insulin in this cohort. OHCA patients were undergone preliminary analysis during cool and warm, which includes insulin sensitivity (SI), blood glucose (BG), and exogenous insulin and dextrose. Patients were analysed based on overall cohort, sub-cohorts, and 6 and 12 hour time block. Generally, the results show that OHCA patients had very low metabolic activity during cool period but significantly increased over time. In contrast, BG is higher during cool period and decreased over time. The analysis is equally important as the controller development since it provides scientific evidence and understanding of patients’ physiology and metabolic evolution especially during cool and warm. Model-based methods can deliver control that is patient-specific and adaptive to handle highly dynamic patients. A physiological ICING-2 model of the glucose-insulin regulatory system is presented in this thesis. This model has three compartments for glucose utilisation, effective interstitial insulin and its transport, and insulin kinetics in blood plasma, with emphasis on clinical applicability. The predictive control for the model is driven by the patient-specific and time-varying insulin sensitivity parameter. A novel integral-based parameter identification enables fast and accurate real-time model adaptation to individual patients and patient condition. Stochastic models and time-series methods for forecasting future insulin sensitivity are presented in this thesis. These methods can deliver probability intervals to support clinical control interventions. The risk of adverse glycaemic outcomes given observed variability from cohort-specific and patient-specific forecasting methods can be quantified to inform clinical staff. Hypoglycaemia can thus be further avoided with the probability interval guided intervention assessments. Simulation studies of STAR-OHCA control trials on ‘virtual patients’ derived from retrospective clinical data provided a framework to optimise control protocol design in-silico. Comparisons with retrospective control showed substantial improvements in glycaemia within the target 4 - 7 mmol/L range by optimising the infusions of insulin. The simulation environment allowed experimentation with controller parameters to arrive at a protocol that operates within the constraints found earlier during patient analysis. Overall, the research presented takes model-based OHCA glycaemic control from concept to proof-of-concept virtual trials. The thesis employs the full range of models, tools and methods to optimise the protocol design and problem solution.

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  • Herschel-ATLAS/GAMA: SDSS cross-correlation induced by weak lensing

    Gonzalez-Nuevo, J.; Lapi, A.; Negrello, M.; Danese, L.; De Zotti, G.; Amber, S.; Baes, M.; Bland-Hawthorn, J.; Bourne, N.; Brough, S.; Bussmann, R.S.; Cai, Z-Y.; Cooray, A.; Driver, S.P.; Dunne, L.; Dye, S.; Eales, S.; Ibar, E.; Ivison, R.; Liske, J.; Loveday, J.; Maddox, S.; Michalowski, M.J.; Robotham, A.S.G.; Scott, D.; Smith, M.W.L.; Valiante, E.; Xia, J-Q. (2014)

    Journal Articles
    University of Canterbury Library

    We report a highly significant (> 10 ) spatial correlation between galaxies with S350μm > 30mJy detected in the equatorial fields of the Herschel Astrophysical Ter- ahertz Large Area Survey (H-ATLAS) with estimated redshifts & 1.5, and SDSS or GAMA galaxies at 0.2 6 z 6 0.6. The significance of the cross-correlation is much higher than those reported so far for samples with non-overlapping redshift distribu- tions selected in other wavebands. Extensive, realistic simulations of clustered sub-mm galaxies amplified by foreground structures confirm that the cross-correlation can be explained by weak gravitational lensing (μ < 2). The simulations also show that the measured amplitude and range of angular scales of the signal are larger than can be ac- counted for by galaxy-galaxy weak lensing. However, for scales . 2 arcmin, the signal can be reproduced if SDSS/GAMA galaxies act as signposts of galaxy groups/clusters with halo masses in the range 1013.2–1014.5M⊙. The signal detected on larger scales appears to reflect the clustering of such halos.

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  • The Economics of Markets

    Evison, D.C. (2014)

    Conference Contributions - Other
    University of Canterbury Library

    There is a large and growing market for chemical pulp in our region (New Zealand’s existing markets). The demand is tied to consumer products that have increasing demand with increasing wealth, and there appears to be a lot of future growth. 22 years of waiting for the solid wood sector to become vibrant and internationally competitive has not yielded the desired result. Declining log prices have not encouraged investment. We need to figure out how to start expansion with pulp as the driver and we need to be able to think of overall profitability of the sector.

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  • Reduction of fouling in falling-film evaporators by design

    Morison, K.R. (2014)

    Conference Contributions - Published
    University of Canterbury Library

    Falling-film evaporators are widely used for the concentration of liquid foods, especially milk prior to spray drying. Given that an evaporator is a heat exchanger, it is often assumed that fouling is similar in heat exchangers and evaporators. This paper describes a number of features of falling-film evaporators that have been studied in recent years, and hence it seeks to show that attention to design detail should lead to lower rates of fouling. Typically fouling is due to poor liquid distribution to the tubes, which leads to drying of the milk films, or causes increases in viscosity to the point where flow stops. The minimum flow rates required to ensure wetting of tubes and flow into the tubes have been established but distributor holes must be correctly sized and drilled to give equal flow to all evaporator tubes. Blockage of distributor holes during operation can be avoided by installation of filters. Vapour flows from flashing or from unequal evaporation in the multiple passes of the same effect can interfere with the liquid flow from distributor plates but this can be overcome by the installation of vapour tubes in distributor plates. When correctly designed and fabricated, it is likely that falling film evaporators can operate in excess of 20 hours without excessive fouling or bacterial growth.

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  • Experimental studies on cyclic behaviour of steel base plate connections considering anchor bolts post tensioning

    Borzouie, J.; MacRae, G.; Chase, G.J.; Clifton, C. (2014)


    University of Canterbury Library

    This paper presents the experimental tests on cyclic behaviour of the base plate connections that are connected to the foundation with and without fully post tensioned anchor rods. The main aim is to evaluate these connections that are designed with available design procedures from the low damage aspect. Also, the effect of post tensioning on the seismic performance of this type of connection is presented. To characterize the base plate connection damageability, each column base was designed for a particular major inelastic deformation mode such as anchor rod yielding, yielding of the column, or column and base plate yielding. It is shown that considered joints are not able to be categorized as “a low damage”. Also, post tensioning of the base plate increases the rotational stiffness of the base, and results in more ductility of the column with low axial force

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  • Predation risk and the evolution of odours in island birds

    Thierry, Aude (2014)

    Doctoral thesis
    University of Canterbury Library

    It is only recently that studies have explored the use of olfaction in birds. Birds are now known to use odour cues for navigation, and locating food. Odours produced by the birds themselves can also function in nest recognition and even mate choice. The odours of most birds stem from the preen wax produced by the uropygial or preen gland. The wax is comprised of a complex mixture of esters and volatiles, and is known to vary in some species with age, sex, season, or environmental conditions. Its function has been associated with feather maintenance, but it may also play a role in sexual selection and chemical communication. In this thesis, I used the preen gland and its preen wax to perform comparative studies on the evolution of odours between island birds and their continental relatives. I used the birds of the Oceania region as a model system, where most passerines originated from continental Australia but have colonised numerous surrounding islands such as New Zealand and New Caledonia. As islands generally lack mammalian predators, and have less parasites and less interspecific competition than continents, these differences in environmental conditions likely shaped functional differences in the preen gland and its products. I measured the size of the preen gland and collected preen wax from a variety of forest passerines in Australia, New Zealand and New Caledonia. I found that island birds have larger preen glands and therefore likely produce more preen wax than their continental relatives. I also found that the preen wax composition differed among species, with a shift to birds on islands producing disproportionately lighter and more volatile compounds. I suggest that selection favoured the gain of more volatile molecules in island birds as they were released from the constraint to camouflage their odours that is imposed by mammalian predators on continental areas. It is possible that this also allowed greater communication through olfactory channels in island birds, and such communication is enhanced through the use of more volatile compounds. To support this hypothesis I showed that the South Island robin (Petroica australis) was able to detect and react to the odour of a conspecific (odours produced by preen wax) in the absence of any visual cues. From a conservation perspective, increased volatility of the preen waxes of island birds might place them at increased risk from introduced mammalian predators that use olfaction to locate their prey. However, in both laboratory tests using Norway rats (Rattus norvegicus), a common exotic predator, and in field trials using rodent tracking tunnels, I found only limited evidence to suggest the odour of island birds places them at greater risk, and more experiments are needed to test this hypothesis. Finally, my findings of more conspicuous odours in island birds suggest new avenues of research for their conservation, including whether island species that seem especially prone to predation have preen waxes (and thus odours) that are also especially attractive to exotic mammalian predators. Conservation programmes to protect endangered island birds may even benefit from considering whether olfactory cues can be minimised as a method of reducing predation risk.

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  • Composite slab effects on beam-column subassemblies: Further development

    Chaudhari, T.; MacRae, G.A.; Bull, D.; Chase, J.G.; Hobbs, M. (2014)


    University of Canterbury Library

    Composite slab construction is gaining popularity in New Zealand. These slabs may influence the beam column joint subassemblies as they exposed to earthquake induced shaking. However several design issues with composite slabs need to be addressed so that they can be used to their full advantage in design. These relate to the ability to consider the slab effect on the beam design strength, the likely statistical variation of beam and slab under strong seismic shocks that will affect the column joint demand and the resistance of the panel zone. In this paper, the experimental test setups are described which considers slab isolation, beam overstrength, full depth slab around the column, low damage connection, and demand on the panel zone. A new concept of slab confinement using a shear key will be presented to form a force transfer mechanism to avoid failure of concrete either in crushing or spalling. Also the development of a non-prying sliding hinge joint low damage connection and its performance under composite slab is discussed. The outcome of this will be useful to develop simple design recommendations for the New Zealand steel standard.

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  • Intenzív osztályon ápolt betegek szoros vércukorszabályozása

    Benyo, B.; Homlok, J.; Ilyes, A.; Szabo Nemedi, N.; Shaw, G.M.; Chase, J.G. (2014)

    Conference Contributions - Other
    University of Canterbury Library

    Invited presentation, abstract made of presentation notes by organisers - Thus, the presentation IS the abstract

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  • 3D printing of porous media at the microstructural scale

    Dimartino, S.; Fee, C.J.; Nawada, S.; Clucas, D.; Huber, T.; Gordon, A.; Dolamore, F. (2014)

    Conference Contributions - Other
    University of Canterbury Library

    What is superficially referred to as ‘packing quality’, a myriad of geometrical parameters governing the interrelations between pores, has only been measured post-hoc in the form of separation efficiency. While several computational studies of chromatography bed microstructures have explored the effects of various packing parameters on dispersion, experimental replication and model validation has remained elusive. Additive manufacturing, or 3D printing, offers the opportunity to manufacture porous media composed of micro-structural elements of different shapes and sizes, and to precisely locate and orient them within the bed. For example, spherical beads with a narrow size distribution can be constructed individually at desired locations within the bed, allowing the creation of specific packing arrangements, i.e. perfectly ordered lattices or random packing mimicking conventionally packed chromatography columns. Further opportunities are to create geometric elements with different shapes or sizes and place them at individual locations within the same bed. Alternatively, the structural focus can shift from the solid-phase to the mobile phase, with the design of complex flow channels within a monolithic bed. These observations led us to propose the use of 3D printing as both a chromatography column production method and as a tool to enable fundamental studies of packed bed microstructures. The main challenges to this approach include achieving sufficient printing resolution to compete with current media in terms of theoretical plate height and developing materials that have appropriate internal porosity and surface functionalities to enable high binding capacity and specificity. Other challenges are as for conventional media, for example good swelling properties, low non-specific adsorption, and the absence of toxicity and leaching. Here, we show examples of progress made to date in creating 3D printed chromatography columns. These include i) micro-structural analyses of columns containing porous beds with a variety of lattice arrangements and channel structures, printed at a maximum current printing resolution of 16 µm and ii) comparison of residence time distributions and flow characteristics for a range of columns, including several printed with different integrated flow distributors and column cross-sections. We demonstrate reasonable fidelity between printed and designed columns and identify current limitations with regard to resolution. Finally, we compare packed beds incorporating deliberately introduced imperfections within packing lattices, including a ‘line defect’ that runs the length of the column and a ‘cluster defect’ consisting of localized voids at various locations within the packing. Experimentally determined reduced plate heights are compared with computational fluid dynamics flow studies.

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  • Engineering Surface Traces for Self-Propulsion of Droplets

    Ng, V.; Nock, V.; Sellier, M. (2015)

    Conference Contributions - Other
    University of Canterbury Library

    Self-propulsion of droplets may facilitate automated synthesis and analysis of small liquid samples in lab-on-a-chip applications1. Building upon previous work by our group2, this research aims to improve the mechanism of self-propulsion by means of prolonging the hydrophilicity of polydimethylsiloxan (PDMS) surface traces, as well as investigate the geometrical limits of trace patterning. To engineer a more sustainable hydrophilic surface, we investigated the grafting of polyvinylpyrrolidone (PVP) on plasma-activated PDMS traces. Our findings show a sustained hydrophilicity for >10 days with PVP. However, self-propulsion for a 1 mm treated channel was observed only on the same day as treatment. Using these optimized conditions we show propulsion of droplets up an incline and discuss how this can be used to determine the propulsion energy.

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  • Supporting Asian immigrant English language learners : teachers’ beliefs and practices.

    Che Mustafa, Mazlina (2015)

    Doctoral thesis
    University of Canterbury Library

    This phenomenological study explores the beliefs and practices of New Zealand early childhood teachers in supporting English acquisition for Asian immigrant English language learners (ELLs). The focus of the study is on the analysis of early childhood teachers’ beliefs about how they can support English acquisition among Asian immigrant ELLs and how these beliefs influence the teachers’ practices in early childhood education (ECE) settings. The theoretical framework of this research draws on a range of sociocultural perspectives, including (i) the sociocultural positions initially defined by Lev Vygostky (1978), (ii) the notion of guided participation articulated by Barbara Rogoff (2003), (iii) theories of second language acquisition discussed by Lantolf and Thorne (2000), and by Krashen (1982, 1985), and (iv) acculturation as addressed by Berry (2001). The main participants of this study were seven early childhood teachers and six Asian immigrant ELLs from two ECE centres. Four Asian parents participated in interviews to ascertain the parents’ perspectives about their children’s learning of English and their maintenance of home language. Research methods for the teachers included observations and semi-structured pre- and post-observation interviews. For each centre, observations were carried out over a six week period which enabled a series of snapshots of how the teachers supported the ELLs as they acquired English. The findings were analysed using thematic analysis, and presented three themes: English dominance, social cultural adaptation, and guided participation. These themes impacted the learning experiences of the Asian immigrant ELLs and other children attending the ECE as well as the teaching approaches of the early childhood teachers. The findings revealed that there were dissonances between the teachers’ beliefs and their practices, as well as variation between individual teachers’ beliefs and practices. Because of a significant increase in the number of ELLs in New Zealand ECE centres, it is important for early childhood teachers to understand the emphasis upon sociocultural theories in the ECE curriculum, so that they can effectively apply these theories to their practices. This study will provide a basis from which to consider how early childhood teachers in New Zealand can draw upon sociocultural perspectives to better support ELLs as they acquire English, while valuing and supporting their linguistic and cultural backgrounds.

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  • The Potential for Augmented Reality to Bring Balance betweenthe Ease of Pedestrian Navigation and the Acquisition of Spatial Knowledge

    Wen, James (2014)

    Doctoral thesis
    University of Canterbury Library

    Being completely lost in an unfamiliar environment can be inconvenient, stressful and, at times, even dangerous. Maps are the traditional tools used for guidance but many people find maps difficult to use. In recent years, new tools like outdoor Augmented Reality (AR) have become available which allow virtual navigation cues to be directly overlaid on the real world, potentially overcoming the limitations of maps. However, it has been hypothesized that lower effort invested in processing navigation guidance may lead to diminished spatial knowledge (SK) thereby making users of such navigation tools far more vulnerable to getting lost should the tools fail for any reason. This thesis explores the research question of how AR and maps compare as tools for pedestrian navigation guidance as well as for SK acquisition and if there is a potential for AR tools be developed that would balance the two. We present a series of studies to better understand the consequences of using AR in a pedestrian navigation tool. The first two studies compared time-on-task performance and user preferences for AR and Map navigation interfaces on an outdoor navigation task. The results were not aligned with expectations, which led us to build a controlled testing environment for comparing AR and map navigation. Using this simulated setting, our third study verified the assumption that AR can indeed result in more efficient navigation performance and it supported the hypothesis that this would come at the cost of weaker SK. In our fourth study, we used a dual task design to compare the relative cognitive resources required by map and AR interfaces. The quantitative data collected indicated that users could potentially accept additional workload designed to improve SK without incurring significantly more effort. Our fifth and final study explored an interface with additional AR cues that could potentially balance navigation guidance with SK acquisition. The contributions of this thesis include insights into performance issues relating to AR, a classification of user types based on navigation tool usage behavior, a testbed for simulating perfect AR tracking in a virtual setting, objective measures for determining route knowledge, the capacity that pedestrian navigation tool users may have for performing additional tasks, and guidelines that would be helpful in the design of pedestrian navigation tools.

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  • High-Rate Space-Time Block Codes in Frequency-Selective Fading Channels

    Chu, Alice Pin-Chen (2012)

    Masters thesis
    University of Canterbury Library

    The growing popularity of wireless communications networks has resulted in greater bandwidth contention and therefore spectrally efficient transmission schemes are highly sought after by designers. Space-time block codes (STBCs) in multiple-input, multiple-output (MIMO) systems are able to increase channel capacity as well as reduce error rate. A general linear space-time structure known as linear dispersion codes (LDCs) can be designed to achieve high-data rates and has been researched extensively for flat fading channels. However, very little research has been done on frequency-selective fading channels. The combination of ISI, signal interference from other transmitters and noise at the receiver mean that maximum likelihood sequence estimation (MLSE) requires high computational complexity. Detection schemes that can mitigate the signal interference can significantly reduce the complexity and allow intersymbol interference (ISI) equalization to be performed by a Viterbi decoder. In this thesis, detection of LDCs on frequency-selective channels is investigated. Two predominant detection schemes are investigated, namely linear processing and zero forcing (ZF). Linear processing depends on code orthogonality and is only suited for short channels and small modulation schemes. ZF cancels interfering signals when a sufficient number of receive antennas is deployed. However, this number increases with the channel length. Channel decay profiles are investigated for high-rate LDCs to ameliorate this limitation. Performance improves when the equalizer assumes a shorter channel than the actual length provided the truncated taps carry only a small portion of the total channel power. The LDC is also extended to a multiuser scenario where two independent users cooperate over half-duplex frequency-selective channels to achieve cooperative gain. The cooperative scheme transmits over three successive block intervals. Linear and zero-forcing detection are considered.

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  • Collateral exposure: the additional dose from radiation treatment

    Fricker, Katherine (2012)

    Masters thesis
    University of Canterbury Library

    For patients receiving radiation therapy, there is a risk of developing radiation induced carcinomas, especially if they have a long life expectancy. However, radiotherapy is not the only contributor of radiation exposure to healthy tissue. With the introduction of highly conformal treatment techniques comes the increase in pretreatment imaging necessary to accurately target tumour volumes and consequently, radiation exposure to healthy tissue. In this work the radiation dose delivered to radiosensitive organs from a number of treatment planning techniques was evaluated and the risk of radiation induced cancer was assessed. MOSFET detectors and Gafchromic film were used to measure the accumulative concomitant dose to the thyroid and contralateral breast from early stage breast carcinoma radiotherapy and to the contralateral testis from seminoma radiotherapy, with dose contributions from CT imaging for treatment planning, pretreatment imaging (CBCT) and treatment delivery peripheral dose. To the author's knowledge this is the first work investigating the total concomitant treatment related dose and associated risk to these treatment sites. Peripheral dose contributed the largest concomitant dose to the healthy tissue, measuring up to 0.7, 1.0 and 5.0 Gy to the testis, thyroid and contralateral breast, respectively. The highest testicular, thyroid and contralateral breast carcinoma risk was found to be 0.4, 0.2 and 1.4%, respectively. In conclusion, the risk of radiation induced carcinoma to the assessed radiosensitive tissues was found to be minimal, however, when considering treatment techniques and/or introducing pretreatment imaging protocols, the dose to the normal tissue should be kept as low as reasonably achievable.

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  • Structure and function of food webs in acid mine drainage streams

    Hogsden, Kristy Lynn (2013)

    Doctoral thesis
    University of Canterbury Library

    Acid mine drainage (AMD) is a significant environmental issue worldwide, which often causes severe contamination and marked species losses in receiving streams. However, little is known about how this stress alters food webs and ecosystem function. I conducted a literature review, which revealed that AMD-impacted streams generally had depauperate benthic communities dominated by a few tolerant species and impaired ecosystem processes. Next, using survey and experimental-based approaches, I investigated food web structure and energy flow in these highly stressed streams, which typically have low pH (< 3), high concentrations of dissolved metals (Al, Fe), and substrata coated with metal hydroxide precipitates, on the South Island, New Zealand. Inputs of AMD caused substantial loss of consumers and reduced the overall number of links between species generating small and simplified food webs, with few invertebrates and no fish. Comparative analysis of food webs from a survey of 20 streams with either anthropogenic or natural sources of acidity and metals, indicated that anthropogenic sources had a stronger negative effect on food web properties (size, food chain length, number of links); an effect driven primarily by differences in consumer diversity and diet. However, the presence of fewer trophic levels and reduced trophic diversity (detected using isotopic metrics), were common structural attributes in AMD-impacted webs along a pH gradient, regardless of impact level. Furthermore, complementary dietary analyses of consumer gut contents and stable isotope signatures (δ13C and 15N) confirmed that primary consumers fed generally on basal resources and that there were few predatory interactions, which reflected low densities of small-bodied chironomids. This suggests that food quantity was unlikely to limit primary consumers but that reduced prey availability may be an additional stressor for predators. In these radically re-structured food webs, trophic bottlenecks were generated at the primary consumer level and energy flow to higher consumers was disrupted. However, streams still retained some limited function, including slow leaf litter breakdown, which provided detrital resources and supported the small food webs. Overall, my findings have furthered our understanding of these highly stressed stream ecosystems by providing new insights into interactions among species and trophic levels that structure food webs and enable function.

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  • A correlational study of cough sensitivity to citric acid and radiographic features of airway compromise

    Moore, Sara Louise (2012)

    Masters thesis
    University of Canterbury Library

    Patients with an impaired reflexive cough response are at increased risk of pneumonia. This study examined the correlation between cough sensitivity to citric acid and radiographic features of airway compromise. Eighty patients referred for a radiographic assessment of swallowing at an acute hospital over an 8-month period participated in the study. Nebulised citric acid diluted in 0.9% sodium chloride was inhaled through a facemask at four concentrations to assess cough sensitivity. These data were then compared to Penetration Aspiration Scale scores based on radiographic swallowing studies. There was a statistically significant correlation between cough response/lack of response and the radiographic features of airway compromise; that is, patients who had a weak or absent response to inhalation of citric acid were also likely to aspirate silently during radiographic assessment. Sensitivity for identifying absent cough was found to be high at all 4 concentrations (0.750, 0.833, 0.941, 1.000), however specificity was consistently quite low (0.344, 0.456, 0.238, 0.078). The significant findings of this research suggest that clinicians adopting cough reflex testing into their clinical practice will have a reliable screen for silent aspiration at bedside. Clinicians will be able to identify patients who require instrumental assessment and are at high risk of pneumonia. This will likely, in turn, decrease length and cost of hospital admissions as well as decrease aspiration pneumonia related morbidities.

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  • God wills it? A comparison of Greek and Latin theologies of warfare during the Medieval period.

    Newman, Timothy John (2013)

    Masters thesis
    University of Canterbury Library

    The history of the Church’s participation in, and attitudes towards warfare have been well-documented in several fields of research. The development of the doctrine of just war and the medieval crusades within Western Christianity, have been the subject of a considerable amount of scholarship. There has also recently been an increasing amount of research done by historians, theologians and political theorists comparing the status of warfare within the Christian and Islamic traditions. However, the current state of the historiography is focused almost entirely on Western Christianity, and does not address in any depth the attitudes toward warfare present in Eastern Christianity within the Byzantine Empire in the Middle Ages. This thesis seeks to address this historiographical imbalance by comparing the development of the Eastern and Western Church’s positions on warfare throughout the medieval period. The thesis examines the factors that led to the divergence of the two Churches’ attitudes towards warfare, and the development and impact of their differing theologies during the medieval period. It is argued that the fundamental point of divergence between the Eastern and Western Church’s attitude to warfare is linguistic and theological in nature. The linguistic differences between the Greek and Latin Churches, led to different theological interpretive frameworks regarding the subject of warfare. These different fundamental theological assumptions would lead the two Churches down different developmental paths and would prevent the development or acceptance of Western theories of just war and holy war in the Eastern Church.

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