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- PublicationImage Quality in Attenuation-Based and Phase-Contrast-Based X-ray Imaging(CRC Press, 2018)This chapter provides an overviews the statistical decision theory and the associated objective image quality assessment. It focuses on the behavior of the noise propagation in computed tomography (CT) imaging systems, with and without in-line phase-contrast. The chapter analyzes the effect on noise of a widely used phase retrieval approach, based on the Transport of Intensity equation (TIE). It presents an approach, based on the noise power spectrum formalism, for quantifying noise in phase retrieved X-ray radiographs, as well as in phase-contrast computed tomography. Using this approach, in-line phase-contrast imaging in combination with a popular TIE-Hom phase retrieval algorithm has been analyzed and compared with conventional imaging in terms of the noise in the reconstructed projections and CT images. A gain factor has been introduced in order to evaluate the improvement of image quality, in terms of the variance of noise, due to phase retrieval.
- PublicationLinking Symbolic Interactionism and Grounded Theory Methods in a Research Design: From Corbin and Strauss' Assumptions to Action(Sage Publications, Inc, 2013)This article focuses on Corbin and Strauss' evolved version of grounded theory. In the third edition of their seminal text, 'Basics of Qualitative Research: Techniques and Procedures for Developing Grounded Theory', the authors present 16 assumptions that underpin their conception of grounded theory methodology. The assumptions stem from a symbolic interactionism perspective of social life, including the themes of meaning, action and interaction, self and perspectives. As research design incorporates both methodology and methods, the authors aim to expose the linkages between the 16 assumptions and essential grounded theory methods, highlighting the application of the latter in light of the former. Analyzing the links between symbolic interactionism and essential grounded theory methods provides novice researchers and researchers new to grounded theory with a foundation from which to design an evolved grounded theory research study.
- PublicationLong-Term Outcomes of On- Versus Off-Pump Coronary Artery Bypass Grafting(Elsevier Inc, 2018)BACKGROUND When comparing effects of on- versus off-pump coronary artery bypass grafting (CABG), it is important to assess the long-term clinical outcomes. However, most research conducted thus far has concentrated on short-term outcomes and ignored the long-term clinical outcomes, especially the 5-year outcomes of the largest randomized controlled trials. OBJECTIVES The aim of this systematic review and meta-analysis was to investigate the long-term clinical outcomes of on- versus off-pump CABG. METHODS To identify potential studies systematic searches were carried out using various databases. The search strategy included the key concepts of cardiopulmonary bypass AND off-pump AND long term OR 5-year outcomes. This was followed by a meta-analysis investigating mortality, incidence of myocardial infarction, incidence of angina, need for revascularization, and incidence of stroke. RESULTS Six studies totaling 8,145 participants were analyzed. In the on-pump group mortality was 12.3%, compared with 13.9% in the off-pump group. The odds ratio (OR) for this comparison was 1.16 (95% confidence interval [CI]: 1.02 to 1.32; p = 0.03; 13.9% vs. 12.3%). In contrast, there were no differences in the incidence of myocardial infarction (OR: 1.06: 95% CI: 0.91 to 1.25; p = 0.45; 8.4% vs. 7.9%), incidence of angina (OR: 1.09; 95% CI: 0.75 to 1.57; p = 0.65; 2.3% vs. 2.1%), need for revascularization (OR: 1.15; 95% CI: 0.95 to 1.40; p = 0.16; 5.9% vs. 5.1%), and the incidence of stroke (OR: 0.78; 95% CI: 0.56 to 1.10; p = 0.16; 2.2% vs. 2.8%). CONCLUSIONS Statistically, on-pump CABG appeared to offer superior long-term survival, although the clinical significance of this may be more uncertain.
- PublicationSpatial landscape utilisation by sheep and its relationship to individual productivity and health(AgResearch Grasslands, 2012)This study explores the relationship between individual animal performance, health and spatial landscape utilisation. Individual animals are known to vary in the way they use landscapes for grazing, camping and travelling activities. There is also clear evidence of variability in production traits between individual animals. However there are few studies linking these two traits and no known studies in sheep. To explore these issues a study is being undertaken in a 46 Ha paddock at Kirby Research Station, Armidale, NSW, Australia. 20 individuals from a mob of 346, 18-month-old fine wool merino wethers, were selected based on race order and weight and UNEtracker GPS collars attached to log their position at 5 minute intervals. The collars were deployed in mid-February 2012 and will remain on the wethers until mid-August 2012. Once a month the sheep will be brought back to the yards where they will be weighed, have mid-side dye-bands put in their wool and have individual faecal samples collected to perform a faecal worm egg count (WEC) for gastrointestinal nematodes followed by a pooled larval differentiation test.
- PublicationA review of the state of vegetation plot data in Western Australia in response to comments by Neil Gibson(Gebrueder Borntraeger Verlagsbuchhandlung, 2018)We respond to Neil Gibson's reply to our paper "Overview of plot-based classification approaches within Australia" where Gibson advised on the location of plot data held by the Western Australian Department of Biodiversity, Conservation, and Attractions (DBCA). Based on that advice we have tabulated the available vegetation plot data on DBCA's NatureMap site. NatureMap stores vegetation plot data as Excel files within data directories rather than in a unified database. We accessed 5,318 vegetation plots from 19 flora surveys sourced from NatureMap and a further 1144 from other government or university sources. In addition, we sourced a further 9,588 vegetation survey sites in a privately-held database. We updated the bioregional analyses of plots for WA, outlined in Gellie et al. 2018, using the combined plot data. It is likely additional data exists that would increase the plot density in Western Australian bioregions. Irrespective, our updated analysis of all the plots we located indicates the quantities are well below that required for either supervised or unsupervised vegetation classification, except for a few sub-bioregional areas. From a practical perspective, the plot data held by DCBA as Excel files are not readily available to external users. Few of the WA data are assigned cover or abundance scores with implications for statistical classification of vegetation types. Adopting a sampling protocol that conforms to a national standard would enhance plot data consistency for recording site and floristic attributes. WA DBCA data could more usefully be stored in a properly constructed centralised vegetation plot database containing government and non-government data maintained to agreed standards with protocols for ensuring plant taxonomy is maintained.