280 results for Conference poster

  • Radiofrequency ablation of osteoid osteoma - aiming for zero recurrence

    Doyle, Anthony; Graydon, A; French, JG; Hanlon, M (2016-04-30)

    Conference poster
    The University of Auckland Library

    Over a 13 year period, a single radiologist (AJD) performed radiofrequency ablation (RFA)of osteoid osteoma in 32 patients. The lesions were located mostly in the lower extremities (femur N=15, tibia N=9) and spine (N=5). Lesion size varied from 4 to 18 mm, average 10 mm. Patient age ranged from 5 to 23 years, average 14 years. All but two had RFA as their primary treatment, with two treated after surgical excision had resulted in recurrence. CT guidance was used for all procedures, performed under general anaesthetic. A variety of different radiofrequency generators and probes were used. No complications occurred. None of the patients showed any signs of recurrence and none required further intervention. Although the followup period varied (and a few patients were lost to followup after a few weeks), most of the patients were followed for at least 12 months post procedure, with maximum followup seven years. We conclude that, with careful technique, the recurrence rate for RFA of osteoid osteoma can approach zero. Details of technique are discussed in the poster itself.

    View record details
  • The potential of urban forests to mitigate atmospheric CO2 concentrations

    Weissert, Lena; Salmond, Jennifer; Schwendenmann, Luitgard (2013)

    Conference poster
    The University of Auckland Library

    The urban population in New Zealand is expected to increase significantly over the next years. Urban areas are generally large sources of anthropogenic carbon dioxide (CO2) emissions. However, attempts to quantify atmospheric CO2 concentrations and fluxes have suggested that densily vegetated urban areas may absorb sufficient quantities of anthropogenic CO2 to act as a local sink. Consequently, urban greening programs now form an important part of many urban climate change mitigation policies globally as well as in New Zealand. However, knowledge about the direct contribution of urban vegetation on atmospheric CO2 concentrations is still limited and measurements scarce. This paper examines the methods used to date to estimate / measure carbon pools and CO2 fluxes from urban vegetation and soils (collectively known as urban forests) and aggregates currently available results. Results from the northern hemisphere show that carbon pools in urban forests were comparable to 3 ??? 60% of the annually released fossil fuel emissions, while photosynthetic uptake accounted for 0.3 ??? 2.6% of the total estimated emissions in urban areas. Whilst vegetation did not offset CO2 emissions on an annual basis in these scenarios, vegetative CO2 uptake resulted in significantly lower atmospheric CO2 concentrations in summer. However, the currently available results are related to a large degree of uncertainty due to the limitations of the applied methods, the limited number of urban areas studied and the temporal / spatial resolution of the fieldwork. This paper demonstrates that in order to effectively quantify and encorporate carbon fluxes from urban areas into annual CO2 budgets, future research needs to use a combination of methodologies and be aware of the scales of their studies. Thus, before investing in urban greening programs the potential of urban vegetation as a climate change mitigation measure needs to be further investigated, particularly for cities in the southern hemisphere.

    View record details
  • An optimal sampling schedule for neonates, infants & children receiving cefazolin +/- vancomycin for cardiopulmonary bypass

    Sturge, Jacqueline; Anderson, Brian; Holford, Nicholas (2016-08-22)

    Conference poster
    The University of Auckland Library

    Background: Dosing of prophylactic antibiotics in children during cardiopulmonary bypass (CPB) remains poorly defined. Pharmacokinetic (PK) studies can be improved using optimal design when sampling is limited, or multiple factors influence PK. We aimed to optimize a sampling schedule designed to determine cefazolin and vancomycin PK in children undergoing CPB. Methods: A one compartment distribution model for vancomycin and a three compartment distribution model for cefazolin was used with theory based allometric scaling and maturation to describe first-order elimination clearance. The CPB circuit was represented by an additional compartment. We assumed 60 subjects received cefazolin 50 mg.kg-1, with 50 of these subjects undergoing a procedure with CPB. We assumed 15 subjects also received 15 mg.kg-1 vancomycin. Optimal times for up to 8 samples per patient were estimated, ignoring CPB effects, using WinPOPT (University of Otago, New Zealand). Optimal sampling times for determination of CPB related changes were considered separately. Designs were selected based on relative standard errors (RSEs) for model parameters and comparison of criterions summarizing design efficiency. Results: Sample times were 0.001, 0.001, 0.108, 0.36, 1.05, 1.85 h following the first dose, and 0.36 and 2.5 h after the second dose, for With CPB subjects. Sample times were 0.127, 0.43, 0.43, 1.3, 3.18, 6, 6 h after the first dose and 6 h after the second dose, for Without CPB subjects. Five samples, taken directly from the CPB circuit, were required to adequately capture CPB related changes in CPB V and CL. RSE estimates of cefazolin, vancomycin and CPB circuit parameters for the final design were ??? 30%, with the exception of one of the cefazolin volumes (V2) for which RSEs were 49%. Conclusion: The sampling schedule may be used in the planning of a clinical study of children receiving cefazolin and vancomycin during CPB.

    View record details
  • Variability in soil CO2 efflux across distinct urban land cover types

    Weissert, Lena; Salmond, Jennifer; Schwendenmann, Luitgard (2015-04-14)

    Conference poster
    The University of Auckland Library

    As a main source of greenhouse gases urban areas play an important role in the global carbon cycle. To assess the potential role of urban vegetation in mitigating carbon emissions we need information on the magnitude of biogenic CO2 emissions and its driving factors. We examined how urban land use types (urban forest, parklands, sportsfields) vary in their soil CO2 efflux.We measured soil CO2 efflux and its isotopic signature, soil temperature and soil moisture over a complete growing season in Auckland, New Zealand. Soil physical and chemical properties and vegetation characteristics were also measured. Mean soil CO2 efflux ranged from 4.15 to 12 molm 2 s 1.We did not find significant differences in soil CO2 efflux among land cover types due to high spatial variability in soil CO2 efflux among plots. Soil (soil carbon and nitrogen density, texture, soil carbon:nitrogen ratio) and vegetation characteristics (basal area, litter carbon density, grass biomass) were not significantly correlated with soil CO2 efflux. We found a distinct seasonal pattern with significantly higher soil CO2 efflux in autumn (Apr/May) and spring (Oct). In urban forests and sportsfields over 80% of the temporal variation was explained by soil temperature and soil water content. The 13C signature of CO2 respired from parklands and sportsfields (-20 permil - -25 permil) were more positive compared to forest plots (-29 permil) indicating that parkland and sportsfields had a considerable proportion of C4 grasses. Despite the large intra-urban variability, our results compare to values reported from other, often climatically different cities, supporting the hypothesis of homogenization across urban areas as a result of human management practices.

    View record details
  • Lower Limb Estimation from Sparse Landmarks using an Articulated Shape Model

    Zhang, Ju; Hislop-Jambrich, J; Besier, Thor (2016-02-19)

    Conference poster
    The University of Auckland Library

    Rapid generation of lower limb musculoskeletal models is essential for patient-specific gait modeling. Motion-capture is a routine part of gait assessment but contains relatively sparse geometric information. We present an articulated statistical shape model of the lower limb that estimates realistic bone geometry, pose, and muscle attachment regions from seven commonly used motion-capture markers. Our method obtained a lower (p=0.02) surface error of 4.5 mm RMS compared to 8.5 mm RMS using standard isotropic scaling, and was more robust, converging in all 26 test cases compared to 20 for isotropic scaling.

    View record details
  • A case of overwhelming sepsis in splenectomised child

    Alkhudairi, Z; Wilson, E; Best, Emma (2015-03-19)

    Conference poster
    The University of Auckland Library

    View record details
  • Population Pharmacokinetics of Ethanol in Moderate and Heavy Drinkers

    Jiang, Y; Holford, Nicholas; Murry, DJ; Brown, TL; Milavetz, G (2015-10-07)

    Conference poster
    The University of Auckland Library

    Objectives: To investigate the effect of sex, age, and previous drinking history on ethanol pharmacokinetic parameters with the implementation of a rate dependent extraction model [1], which takes into account the change in hepatic first-pass extraction along with absorption rate and a body composition model that accounts for fat free mass and fat mass [2]. Methods: 108 moderate or heavy drinkers were dosed orally on 2 occasions to achieve a peak blood ethanol concentration of 0.65 g/L or 1.15 g/L using a randomized, crossover design. A total of 6025 breath measurements were obtained and converted into blood alcohol concentration by applying a blood: breath ratio of 2100:1. NONMEM 7.3.0 was used for data analysis. A semi-mechanistic rate dependent extraction model with zero-order input followed by first order absorption was utilized with V allometrically scaled by normal fat mass, Vmax allometrically scaled by total body weight and portal vein blood flow allometrically scaled by fat free mass. The effects of sex and age (21???34, 38???51, or 55???68 years of age) on V, Vmax, and Km; and the effect of drinking status (moderate or heavy drinkers) on Vmax and Km were explored. The covariate effect was considered to be statistically significant if the 95 % non-parametric bootstrap confidence interval of the fractional difference did not include 1. Results: The 95 % bootstrap confidence interval of fractional differences between groups in age, sex and ethanol consumption history all contain 1, indicating none of those covariates have significant effects on any ethanol disposition parameters. Conclusions: Age and sex were not regarded as significant predictors for ethanol disposition parameters after accounting for body size and composition. The results indicated a 19 % higher Vmax and 15 % lower Km for heavy drinkers compared with moderate drinkers, but the difference was not statistically significant.

    View record details
  • Similar estimates of contrast sensitivity and acuity from psychophysics and automated analysis of optokinetic nystagmus

    Dakin, Steven; Turnbull, Philip (2016-05-14)

    Conference poster
    The University of Auckland Library

    Although the contrast sensitivity function (CSF) is a particularly useful way of characterising functional vision, its psychophysical measurement relies on observers being able to make reliable perceptual reports. This can be challenging e.g. when testing children. Here we describe a system for measuring the CSF without observer-report using an automated analysis of optokinetic nystagmus (OKN), an oscillatory eye movement made in response to moving stimuli (here, spatial-frequency - SF - band-pass noise). We show that predicting perceived direction using the proportion of eye movements that are consistent with OKN in the stimulus direction allows us to make an unbiased estimate of contrast sensitivity across SF. We next compare CSFs of 25 observers derived using either OKN or perceptual report. Both approaches yield near-identical CSFs that capture subtle inter-observer variations in acuity (R=0.80, p< 0.0001) and contrast sensitivity (R=0.80, p< 0.0001) amongst observers with ostensibly normal vision. A trial-by-trial analysis reveals that, even when observers' perceptual report is at chance, there is a very high correlation between our OKN-derived measure and observers' perceptual report. This indicates that OKN and self-report are likely tapping into a common neural mechanism providing further support for the proposal that OKN is a valid alternative to the current gold standard measures of CSF based on perceptual report. We discuss how our approach can be paired with an efficient psychophysical method to derive rapid automated measures of the CSF and other measures of functional vision.

    View record details
  • Evaluation of liquefaction susceptibility using the critical state soil mechanics concept

    Orense, Rolando; Tan, Wei Yoong (2016-04-01)

    Conference poster
    The University of Auckland Library

    View record details
  • Persistent radial glial cells in the adult human and sheep SVZ differentially express Fatty Acid Binding proteins (FABPs)

    Dieriks, Birger; Dean, Justin; Faull, Richard; Curtis, Maurice (2014-07-07)

    Conference poster
    The University of Auckland Library

    View record details
  • The relation between the physico-chemical characteristics of thermal water and the nature of their siliceous sinter deposits

    Nicolau del Roure, C; Reich, M; Lynne, Bridget (2012-08-08)

    Conference poster
    The University of Auckland Library

    Siliceous sinters (hot spring rocks) form by evaporation of near-neutral, alkali-chloride silica-rich thermal waters. Their importance resides in their capacity for recording environmental conditions and their relation to the existence of a geothermal reservoir at depth. Previous studies have shown that sinter textures are commonly controlled by hydrodynamic conditions, whereas their mineralogy and chemistry is controlled by chemical composition of thermal waters. However, the effect of altitude, wind velocity and discharge rate are still poorly constrained. Here we present preliminary data of an experiment developed at the El Tatio geothermal field in northern Chile, designed to determine silica accumulation rates and textures developed in sinter, and their relationship to environmental and hydrodynamic conditions.

    View record details
  • FPGA based acceleration of FDAS module for pulsar search

    Wang, H; Sinnen, Oliver (2015-12-07)

    Conference poster
    The University of Auckland Library

    The Square Kilometre Array (SKA), currently in the pre-construction phase, will be the world largest telescope array for radio astronomy. The Fourier domain acceleration search (FDAS) is a sub-module of the Non-imaging Processing Pulsar Search Sub-element (NIP PSS) of SKA-MID Central Signal Processor (CSP) element. The total performance needed for FDAS module of up to 2000 beams is over 14Poperations/s. The huge scale of it is a strong computing challenge. In this work, the use of FPGAs to accelerate the FDAS module is studied, due to their high inherent parallelism and power efficiency. We study the impact of the relaxation of a number of FDAS factors and test them using a Terasic DE5 board. By applying all the relaxation methods, up to 93% FPGAs can be saved. Further, several optimization techniques are introduced to reduce the number of needed FPGAs.

    View record details
  • Explaining parallel computing to your grandmother: Drive-by learning for developing soft skills by communicating with a general audience

    Varoy, E; Aziz, M; Burrows, J; Sinnen, Oliver; Giacaman, Nasser (2016-05-23)

    Conference poster
    The University of Auckland Library

    View record details
  • First proteomic profiling of exosomes in rodent intestinal lymph

    Hong, Jiwon; Nachkebia, S; Tun, SM; Premkumar, R; Blenkiron, C; Windsor, John; Phillips, Anthony (2016-05-06)

    Conference poster
    The University of Auckland Library

    Introduction: Exosomes are released by many cell types and can be taken up by other cells. They may play an important role in cell-to-cell communication and disease pathogenesis. Exosomes derived from plasma or urine have been extensively studied, but that of intestinal lymph has not been reported due to the difficulty in obtaining these samples. Intestinal lymph is continuously draining from the intestine and enters the veins just before the heart and lungs. These organs may therefore be directly influenced by intestinal exosomes. Methods: Intestinal lymph was collected from a rodent experimental model of critical illness. Exosomes were isolated from the intestinal lymph using a commercially available exosome isolation kit. Particle size and concentration were determined by Nanosight. Proteomic profiling of lymph exosomes and its changes in critical illness were analysed by LC-MS. Results: The size and concentration of ???exosomes??? isolated from the intestinal lymph did not change significantly in the critical illness. The exosome preparation contained proteins previously identified in microparticles or exosomes (e.g. inter-alpha trypsin inhibitor), but also the highly abundant plasma proteins (e.g. complement C3, albumin). Common exosomal markers (e.g. TSG101, CD63) were not detected. Instead, substantial amounts of Apo B and A-I were found, indicating presumed co-isolation of chylomirons. Lymph chylomicrons are similar to size of ???exosomes???, and produced in high concentration from the intestine. Our study indicates the unexpected difficulty in isolating pure exosomes using a commercial kit in this unique fluid. Conclusion: This present study provides the first attempt at a proteomic profile of an exosome preparation from intestinal lymph. Collectively, multiple proteins were identified, but found to have come from both exosomes and chylomicrons. New purification methods will be needed to study pure isolates of each particle type in this unique fluid.

    View record details
  • What should be stored in Biobanks? Using computational modelling to unravel genotype to phenotype linkage

    Cooling, Michael; Atalag, Koray (2016-10-31)

    Conference poster
    The University of Auckland Library

    View record details
  • Gorgeous Gallery: residential aged care in New Zealand, in pictures

    Broad, Joanna (2015)

    Conference poster
    The University of Auckland Library

    View record details
  • Duration of intravenous antibiotics post-operatively in complicated appendicitis: is there a difference in complication rates?

    Chung, L; Paterson, J; Devathasan, J; MacCormick, Andrew (2017)

    Conference poster
    The University of Auckland Library

    View record details
  • Clinical prediction rules for appendicitis in adults: Which is best?

    Kularatna, M; Lauti, Melanie; Haran, C; MacFater, W; Sheikh, L; Huang, Y; McCall, J; MacCormick, Andrew (2017)

    Conference poster
    The University of Auckland Library

    View record details
  • Empirical liquefaction-induced lateral displacements relationship using Lidar data of the Canterbury earthquake sequence

    Wu, C; Orense, Rolando (2016-04-01)

    Conference poster
    The University of Auckland Library

    View record details
  • A trial of image-based dietary records to monitor intake and improve dietary habits, knowledge and behaviours in elite athletes

    Gemming, L; Simpson, A; Braakhuis, Andrea (2017-06-07)

    Conference poster
    The University of Auckland Library

    View record details