47 results for Conference poster, 2008

  • Distributions of gene tree branch lengths under coalescence

    Degnan, J.; Kubatko, L. (2008)

    Conference poster
    University of Canterbury Library

    In Bayesian phylogenetic inference, commonly used prior distributions for branch lengths are the uniform, exponential, and gamma distributions. We derive the exact distributions of branch lengths of gene trees under a fixed species tree using the coalescent model. We find that the distributions of branch lengths depend on both the shape and branch lengths of the species tree, which depend on the population genetic parameters of ancestral population sizes and divergence times. Distributions of branch lengths are formed by mixtures depending on the ancestral populations in which coalescent events occur (coalescent histories). For some sets of moderately short branches, these mixtures can lead to distributions of branch lengths which are not well approximated by uniform, exponential, or gamma distributions, thus suggesting that a prior based on a mixture of distributions might be more appropriate for inferring branch lengths on some gene trees.

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  • An Ultra-Cheap Grid Connected Inverter for Small Scale Grid Connection

    Ghimire, P.; Wood, A.R. (2008)

    Conference poster
    University of Canterbury Library

    This paper reports on the development of a cheap and simple grid connected inverters. It is intended for an integration of a small power photo-voltaic or wind turbine to a grid at low cost. The proposed inverter uses the single cycle control technique, which reduces switching complexity and forces the current waveform to match the voltage waveform. The control circuit operation for unity power factor output is explained. The method is simulated on PSCAD program for single phase system. The simulation output exhibits excellent performance with few components. The paper only considers the current wave-shaping control of the inverters and does not discuss other aspects of control such as maximum power point tracking. The simulations are compared with the prototype waveforms.

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  • Estimating Uncertainty in Wildlife Population Estimates

    Brown, J.A.; McDonald, L.; Robinson, T. (2008)

    Conference poster
    University of Canterbury Library

    Estimating an index of animal population size from simple counts can be very challenging. If indices are to be compared among years to assess trend there must be some consistency in what fraction of the population the index is measuring. Variation in population indices among years may be due to variation in the size of the population but it may also be due to variation in counting procedure, in animal detection and, for migratory and foraging animals, in the proportion of the total population available to be counted. We discuss two case-studies of animal counts where we attempt to quantify this extra variation, or uncertainty, using Monte Carlo simulation. In the first case-study we assess uncertainty in penguin population indices from counts, and in the second, we assess uncertainty in migratory bird counts from braided rivers in New Zealand.

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  • ComposAR: An Intuitive Tool for Authoring AR Applications

    Seichter, H.; Looser, J.; Billinghurst, M. (2008)

    Conference poster
    University of Canterbury Library

    This paper introduces ComposAR, a tool to allow a wide audience to author AR and MR applications. It is unique in that it supports both visual programming and interpretive scripting, and an immediate mode for runtime testing. ComposAR is written in Python which means the user interface and runtime behavior can be easily customized and third-party modules can be incorporated into the authoring environment. We describe the design philosophy and the resulting user interface, lessons learned and directions for future research.

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  • Nitrogen dioxide exposure inside and outside of primary schools

    Holland, K.; Kingham, S. (2008)

    Conference poster
    University of Canterbury Library

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  • Augmented Assembly using a Mobile Phone

    Hakkarainen, M.; Billinghurst, M.; Woodward, C. (2008)

    Conference poster
    University of Canterbury Library

    We present a mobile phone based augmented reality (AR) assembly system that enable users to view complex models on their mobile phones. It is based on a client-server architecture, where complex model information is located on a PC, and a mobile phone with the camera is used as a thin client access device to this information. With this system users are able to see an AR view that provides step by step guidance for a real world assembly task. We also present results from a pilot user study evaluating the system, showing that people felt the interface was intuitive and very helpful in supporting the assembly task.

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  • Clinical Data Validation of an improved, physiologically relevant Critical Care Glycaemic Control Model

    Pretty, C.G.; Parente, J.; Razak, N.; Lin, J.; LeCompte, A.J.; Shaw, G.M.; Hann, C.E.; Chase, J.G. (2008)

    Conference poster
    University of Canterbury Library

    Introduction: Stress induced hyperglycaemia is prevalent in critical care. Tight glycaemic control is associated with significantly improved clinical outcomes. Providing tight control is difficult due to evolving patient condition and drug therapies. Model-based/derived methods (e.g. SPRINT) have shown significant mortality reductions. This research validates an improved metabolic control model and its parameters based on predictive capability for use in real-time glycaemic control.

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  • MEGA : complete sample

    Cseresnjes, P.; Bergier, A.; Crotts, A.P.S.; de Jong, J.; Kuijken, K.H.; Baltz, E.A.; Widrow, L.M.; Brogt, E. (2008)

    Conference poster
    University of Canterbury Library

    MEGA (Microlensing Exploration of the Galaxy and Andromeda) surveyed a roughly 1 deg2 field in central M31 where the magnitude and variation of microlensing optical depth is suspected to be greatest. These observations were concentrated in 1999- 2003, but with extended coverage spanning 1997-2007 (continuing now at sparse cadence). The imaging observations were performed primarily on the 2.5-meter Isaac Newton Telescope (INT), the Kitt Peak National Observatory (KPNO) 4-meter and MDM Observatory 2.4-meter and 1.3-meter telescopes. The current work signifies our merging of these four datasets into a single time sequence.

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  • In vivo effects of hyperosmotic perilymph perfusion on hair cell and neural potentials

    O'Beirne, G.A.; Patuzzi, R.B. (2008)

    Conference poster
    University of Canterbury Library

    The effect of osmotic bias on cochlear potentials was investigated by perfusion of scala tympani with a modified artificial perilymph. The mean osmolality of the artificial perilymph was increased by around 15% (from 303 ± 6 mOsm/kg H2O to 349 ± 1 mOsm/kg H2O) by addition of sucrose. OHC function was assessed using Boltzmann analysis of the low-frequency CM. Neural thresholds and waveforms were monitored at multiple frequencies, and spontaneous neural noise was monitored via a round-window electrode. The 2-minute perfusions caused a 6 ± 4% increase in the maximal CM amplitude, indicating an increase in OHC basolateral permeability, and an 8 ± 1% increase in MET sensitivity, which may reflect a decrease in OHC axial stiffness. The operating-point shifts recorded were more variable: in healthy animals, the hyperosmotic perfusions caused initial operating point shifts towards scala vestibuli of around 1 – 2 meV that were either followed by a brief undershoot towards scala tympani, or initiated a longer-lasting scala tympani operating point shift. Nonetheless, these operating point shifts were smaller than expected, resulting in a less than ±2 meV deviation from the starting point. Neural thresholds during the perfusion fell (by 20 – 30 dB at 22 kHz), and recovered with a time course consistent with the predicted perilymphatic sucrose concentrations at the corresponding BM place for each frequency. The mechanism of the changes observed with these hyperosmotic perfusions is not known, but its effects were not consistent with a simple movement of the reticular lamina towards scala vestibuli. Other data (Marcon and Patuzzi, in preparation) indicate the CAP threshold shifts during these perfusions are most likely mechanical in origin. The experimental results from the guinea pig are compared with simulated perfusions carried out in a mathematical model of cochlear regulation based on the ionic transport mechanisms and motile properties of the outer hair cells.

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  • Clinical supervisor characteristics valued by practising speech-language therapists

    Mataiti, H.; McAuliffe, M.J.; Tillard, G. (2008)

    Conference poster
    University of Canterbury Library

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  • Influence of auditory distraction upon intelligibility ratings in dysarthria

    McAuliffe, M.J.; Good, P.V.; O'Beirne, G.A.; LaPointe, L.L. (2008)

    Conference poster
    University of Canterbury Library

    Communication exchange occurs under a variety of adverse listening conditions. Research has demonstrated that the intelligibility of both normal and synthesised speech declines significantly in noise; however, it is not currently known if the intelligibility of dysarthric speech is similarly affected. To investigate the affect of increasing background noise levels on intelligibility, 56 female listeners rated the intelligibility of dysarthric and control speakers under various conditions of auditory distraction including: (1) no noise, (2) +3 dB signal-to-noise ratio (SNR), (3) 0 dB SNR, and (4) -3 dB SNR. Multi-talker babble was digitally mixed with the speech samples of the dysarthric and control speakers to produce the three SNR conditions. Intelligibility was rated using direct magnitude estimation. Results of the study revealed that the intelligibility ratings of the control group decreased significantly as SNR decreased. Unexpectedly, the intelligibility ratings of the dysarthric group were similar across all conditions of auditory distraction. It is possible that the effort required to attend to the dysarthric speech samples served to obviate the effects of auditory distraction. Alternatively, the findings may reflect a measurement effect with listeners restricted in their ratings due to the overall severity of the dysarthric group.

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  • Development of Passive Treatment Systems for Treating Acid Mine Drainage at Stockton Mine

    McCauley, C.; O'Sullivan, A.D.; Weber, P.; Trumm, D. (2008)

    Conference poster
    University of Canterbury Library

    Acid mine drainage (AMD) at Stockton Coal Mine emanates from the oxidation of pyrite within carbonaceous mudstones during mining, which subsequently releases acidity resulting in metals leaching from overburden. Water chemistry and flow were monitored at numerous seeps at Stockton. Manchester Seep, which daylights at the toe of an overburden embankment, was chosen to conduct research pertaining to development of passivetreatment systems for neutralizing acidity and sequestering metals in AMD. Median dissolved metal concentrations were 62.9 mg/L Fe, 32.5 mg/L Al, 0.0514 mg/L Cu, 0.175 mg/L Ni, 0.993 mg/L Zn and 0.00109 mg/L Cd. Sulphate-reducing bioreactors were chosen as the most feasible passive treatment technology for remediation of Manchester Seep AMD. Chemical and geotechnical parameters, including hydraulic conductivity, were determined for mixtures of organic and alkaline waste products suitable for use as bioreactor substrates. Seven mesocosm-scale bioreactors were fed aerated AMD (collected from Manchester Seep) in a laboratory for nearly four months. Bioreactors incorporating mussel shells performed the best and were capable of sequestering >0.80 mol metals/m3 substrate/day (or neutralising acidity at rates >66 g CaCO3/m2/day) while removing >98.2% of metals. Tracer studies were later conducted on two bioreactor systems containing the same substrate composition but different reactor shapes. Results will be applied to reactor models to better ascertain the relationship between reactor hydraulics and treatment performance. Pilot-scale treatment schemes incorporating three treatment stages were recently constructed to treat a portion of Manchester Seep AMD. The first stage consists of a sedimentation basin to remove sediment. The second stage includes three bioreactors in parallel to test treatment effectiveness of different substrate mixtures, depths and hydraulic configurations. Data derived from the lab study were used to optimise these designs. The final treatment stage consists of three different aerobic wetland configurations operated in parallel to compare their effectiveness at providing oxygenation and tertiary treatment of metals (primarily Fe) from bioreactor effluent.

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  • Growth of microalgal-bacterial biomass on primary treated wastewater

    Turner, S.J.; Biswas, K.; Valigore, J.M.; O'Sullivan, A.D. (2008)

    Conference poster
    University of Canterbury Library

    The use of microalgae as an economically viable feedstock for biofuel production requires development of efficient methods for growth and harvest of biomass. Here we describe a preliminary investigation of the growth and settling characteristics of microalgal-bacterial biomass using primary treated wastewater from the Christchurch Wastewater Treatment Plant (CWTP) as a nutrient source. Sequencing batch reactors (SBRs) were established using a mixture of oxidation pond and primary treated wastewater from CWTP. Microalgal-bacterial flocs were developed by systematically discarding the non-settleable material (supernatant) and retaining settleable solids within the reactors. Subsequent addition of activated sludge (AS) improved the settleability of the biomass but resulted in development of anaerobic conditions and increased the ammonia, COD, and TSS concentrations in reactor supernatants. Analysis of 16S ribosomal RNA (rRNA) gene clone libraries prepared from settleable and suspended (supernatant) fractions revealed distinct differences in the bacterial community structure. Settled biomass was dominated by Firmicutes (45%) of which 80% were members of the Clostridia. Proteobacteria were also abundant (39%) and included, in order of dominance, the γ- (20%) β- (10%), and α- (8%) classes. In contrast, the supernatant community was dominated by β- Proteobacteria (60%) followed by Firmicutes (26%). Further studies are planned to verify these results and determine the possible bioflocculation role of Proteobacteria in this context.

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  • MARS: Colour x-rays of people

    Butler, A.P.H.; MARS-CT Team (2008)

    Conference poster
    University of Canterbury Library

    Goal: To produce a poster for New Zealand high schools explaining a new form of medical imaging. Background: The MARS team has developed an novel x-ray scanner which produces three dimensional spectroscopic x-ray images of small animals and pathology specimens. The scanner, dubbed MARS (Medipix All Resolution System), has been built by University of Canterbury physicists and engineers. The scanner uses the Medipix photon processsing x-ray detector. It is now being used by the radiology department of the University of Otago, Christchurch to establish clinical applications. Method: To convey the difference between traditional medical x-ray systems and spectroscopic systems we used the analogy of observing patterns in a stained glass windows using visible light. To present our initial results, MARS images are shown next to conventional non-spectroscopic CT images. Colour was chosen to display the spectroscopic nature of the MARS images. Results: The poster will be used for the “Medical Imaging Outreach Kit”. The kit also contains a short video on the MARS project and equipment for demonstrating a range of radiation physics. Conclusion: The analogy of colour is felt to be useful for for explaining spectroscopy. It is accurate as the spectroscopic information in x-rays is equivalent to colour for visible light, except in a different part of the electromagnetic spectrum. In future we will solicit feedback from high school teachers and from the outreach program's speakers to further refine our explanation of the MARS technology.

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  • The role of auditory feedback in speech production

    Katseff, S.; Houde, J.F. (2008)

    Conference poster
    University of Canterbury Library

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  • Research Initiatives for Developing Passive-Treatment Technologies for Ameliorating Acid Mine Drainage in New Zealand

    McCauley, C.A.; O'Sullivan, A.D.; Weber, P.A.; Trumm, D.A.; Brough, A.K.; Milke, M.W. (2008)

    Conference poster
    University of Canterbury Library

    Water chemistry was monitored monthly for ten months from an acid mine drainage (AMD) seep emanating at Stockton Coal Mine within the Mangatini watershed in New Zealand. Metal concentrations of the seep water were Fe (4.31-146 mg/L), Al (7.43-76.7 mg/L), Cu (0.0201-0.0669 mg/L), Ni (0.0629-0.261 mg/L), Zn (0.380-1.39 mg/L), Cd (0.000540-0.00134 mg/L) and Pb (0.0049-0.0056 mg/L), pH was 2.49-3.34 and total acidity (pH 8.3) was 78.5-626 mg/L as CaCO3. Water chemistry signature prompted laboratory mesocosm studies measuring the effectiveness of sulfate-reducing bioreactors (SRBRs) for generating alkalinity and sequestering metals. Alkaline materials utilized in the SRBRs included industrial waste products such as mussel shells, nodulated stack dust (NSD) derived from the cement industry, and limestone. Organic substrate materials included post peel, a by-product from fence post manufacture, Pinus radiata bark and compost. Seven SRBRs comprised of varying substrate mixes received aerated AMD for nearly four months. AMD was sourced from the pond that collected the seep water. The SRBR containing NSD successfully removed all metals, but effluent was caustic with pH>9. Bioreactors consisting of 20-30% mussel shells were most successful at immobilizing metals and generating circumneutral effluent. Systems containing mussel shells sequestered more than 0.8 moles of metals/m3 of substrate/day at stable operating conditions and yielded effluent concentrations (removal efficiencies) of 0.120-3.46 mg/L Fe (96.5-99.8%), 0.0170-0.277 mg/L Al (99.5-99.9%), 99.7->99.9%), 99.7%), < 0.00005 Cd (>98.3->98.9%) and <99.7%). The system consisting of limestone as the only alkalinity generating material was less effective (15.4-64.3 mg/L Fe). Results from duplicate systems but different reactor shapes indicated reactor dimensions influence flow characteristics and therefore treatment efficacy.

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  • Cell proliferative and radioprotective properties of bioactive Salvia sclareoides extracts

    Ruivo, D; Silva, FVM; Rauter, AP; Justino, J; Goulart, M (2008-11)

    Conference poster
    The University of Auckland Library

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  • What drives bacterial community structure in stream biofilms?

    Roberts, Kelly; Lear, Gavin; Turner, Susan; Lewis, Gillian (2008-08-17)

    Conference poster
    The University of Auckland Library

    BACKGROUND The microorganisms within biofilms are the key basal trophic level within most freshwater systems. However, microbial structure, function and succession in natural stream systems remain poorly understood. This research characterises the biofilm community structure of stream biofilms experiencing different anthropogenic impacts and how they change over time. Our aim is describe the changes in bacterial biofilm communities over time and to investigate what drives these changes.

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  • Human Activities Modify Bacterial Diversity in Stream Benthic Biofilm Communities

    Lewis, Gillian; Roberts, Kelly; Turner, Susan; Lear, Gavin (2008-06-01)

    Conference poster
    The University of Auckland Library

    This study tests the hypothesis that human impact is an important driver of stream biofilm bacterial population diversity. The seasonal bacterial composition of biofilm in 4 streams with different levels of human impact was determined over 2 years. Bacterial diversity derived from 16S rDNA clone libraries, shows both between stream differences and seasonal transitions in bacterial occurrence and population dominance at a class and genus level. Diversity analysis calculated on pooled seasonal data (class level identification) shows that while composition of the populations are different there is a similar level of both bacterial richness and bacterial diversity in each stream. Trends in bacterial occurrence suggest that the most degraded stream were dominated by cyanobacteria, the mid range impact streams by aeromonads and gamma proteobacteria, while the unimpacted stream showed both high diversity and no dominance by any particular class.

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  • An Approach for Evaluating Robustness of Edge Operators using Real-World Driving Scenes

    Al-Sarraf, Ali; Vaudrey, Tobi; Klette, Reinhard; Woo, Young Woon (2008)

    Conference poster
    The University of Auckland Library

    Conference Details: 2008 23rd International Conference Image and Vision Computing New Zealand Lincoln University, Christchurch, 26-28 November 2008. http://www.lvl.co.nz/ivcnz2008/ Over the past 20 years there have been many papers that compare and evaluate di erent edge operators. Most of them focus on accuracy and also do comparisons against synthetic data. This paper focuses on real-world driver assistance scenes and does a comparison based on robustness. The three edge operators compared are Sobel, Canny and the under-publicized phase-based Kovesi-Owens operator. The Kovesi- Owens operator has the distinct advantage that it uses one pre-selected set of parameters and can work across almost any type of scene, where as other operators require parameter tuning. The results from our comparison show that the Kovesi-Owens operator is the most robust of the three, and can get decent results, even under weak illumination and varying gradients in the images. Keywords: edge operators, edge robustness evaluation, Kovesi-Owens, phase operators

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