University of Melbourne Institutional Repository

    Consolidation effects on uplift capacity of shallow horizontal plate anchors in dilating sand

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    This paper examines the effect of consolidation on a shallowly embedded horizontal plate anchor in medium dense and dense sand using centrifuge tests, where the loading rate was varied over four orders of magnitude. The experimental results show a 4.8 to 5.5 times increase in anchor capacity as the consolidation condition changes from drained to undrained, driven by a steadily increasing negative excess pore pressure with increasing loading rate. At the highest loading rate, under undrained conditions, the measured maximum negative excess pore pressures reaches a steady limit suggesting the occurrence of cavitation. This increase in anchor capacity with non-dimensional displacement rate is captured using a ‘backbone curve’ interpretation framework that describes the change in capacity between the limiting values of drained and undrained anchor capacity. Calculation of drained anchor capacity is straightforward relative to the more challenging problem of calculating undrained capacity, particularly during cavitation. This was addressed separately through a numerical parametric study (pure undrained analysis) using a bounding surface soil model involving different water depths (cavitation potential), densities and embedment ratios. The numerical results are then systematised into a simple extended analytical solution to allow estimation of undrained anchor capacity under different densities and water depths

    Performing Te Whare Tapa Whā: building on cultural rights to decolonise prison theatre practice

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    Ngā Pātū Kōrero: Walls That Talk (2019) is a documentary theatre production staged by incarcerated men at Unit 8 Te Piriti at Auckland Prison in Aotearoa New Zealand. The performance was built around Te Whare Tapa Whā (The House of Four Sides) – a model of Māori health that participants engaged with as part of their therapy for being convicted of sex offences. This article discusses the use of masks in performance and the significance of Te Whare Tapa Whā as a dramaturgical device. What insights for decolonising prison theatre practices can be advanced by building on foundations of cultural rights

    Assimilation of the column-averaged CO2 concentrations from the Orbiting Carbon Observatory-2 (OCO-2) satellite data to improve our knowledge of Australian carbon flux estimates

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    © 2021 Yohanna Lesly Villalobos CortesExisting estimates of carbon fluxes for Australia primarily rely on process-based terrestrial ecosystem model simulations. Even though they are built to consider important ecosystem processes that control the exchange of CO2 between the land surface and the atmosphere, such as the connection between carbon uptake and water use by plants, their carbon flux exchange estimates are highly uncertain. Improving carbon flux estimates from global ecosystem models and its uncertainties is essential for advancing our understanding of the Earth system and carbon cycle-climate feedback. This dissertation contributes to solving this challenge through atmospheric data assimilation, also known as inverse modelling. The main structure of this thesis consists of three studies. The first study involved running a series of simulation experiments (OSSEs) to assess the potential of the Orbiting Carbon Observatory-2 (OCO-2) satellite retrievals to reduce the uncertainties in CO2 fluxes over Australia for 2015. In this study, we assumed that most of the uncertainties in the Australian carbon fluxes were driven by the net primary productivity estimated by the CABLE land surface model (Australian land biosphere model). After performing OSSEs, we found that Australian carbon flux uncertainties can be reduced by up to 90 percent at a grid-point resolution over productive ecosystems. Given that the first study showed promising results about the potential of OCO-2 data to constrain fluxes around Australia, the second study focused on the quantification of CO2 sources and sinks over the continent. The main results of this study suggest that Australia acted as a carbon sink of -0.41 +- 0.08 PgC/y compared to the prior estimate 0.09 +- 0.2 PgC/y (excluding fossil fuel emissions). Analysis of the seasonal variation of the posterior CO2 fluxes aggregated by bioclimatic regions shows that the savannas in northern Australia and the sparsely vegetated ecosystem in central Australia were the primary drivers of stronger carbon uptake in 2015. Examination of the enhanced vegetation index (EVI) indicates that the primary reason for the stronger posterior carbon uptake (relative to the prior) registered over the savanna ecosystem was due to an increase of vegetation productivity (positive EVI anomalies) caused by an anomalous increase of rainfall in summer period. Additionally, we found that a slight increase of carbon over areas with sparse vegetation (the largest ecosystem by area in Australia), was also driven by a slight increase in land productivity and had a substantial impact on the Australian carbon budget for 2015. Underestimation of the gross primary productivity flux simulated by the CABLE model over the savanna and sparsely vegetated ecosystem was also a contribution of why OCO-2 lead to a stronger carbon estimate in 2015. The final study was built upon the second study and focused on understanding the Australian carbon flux variability from 2015-2019 and evaluating how Australian semi-arid ecosystems responded to changes in rainfall and temperature anomalies. This study suggests the 2015 carbon sink's size over Australia increased in 2016 due to increased vegetation productivity in this period. Australia's 2016 carbon uptake contributed almost all the long-term mean terrestrial sink estimated for 2015-2019 (-0.33 +- 0.09 PgC/y). The ecosystems that most contributed to this carbon sink were savanna and sparsely vegetated regions driven by a higher than expected greenness in vegetation (expressed by positive EVI anomalies) strongly influenced by positive rainfall anomalies and negative air temperature anomalies

    Review article: A primer for clinical researchers in the emergency department: Part VII. Considering a research higher degree in emergency medicine: How does it work, where to start, what to consider

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    In this series we address important topics for clinicians who participate in research or are considering research as part of their career path in emergency medicine. While much emergency research is successfully done by clinicians without a research higher degree (RHD), undertaking a master's degree or doctorate allows a research topic to be pursued in greater depth. It also provides a solid basis for a future research career in terms of research quality, advanced skills, academic progression and track record, as well as eligibility for grants and RHD supervision. The decision to undertake a RHD is not an easy one, and requires consideration of the time and cost involved, as well as the impact on a clinician's life plans. However, the expertise provided through a RHD often ultimately complements clinical training and establishes an excellent foundation for future research and career. This article provides an overview of RHDs and what to consider before embarking on one

    Prevalence and progression of diabetic nephropathy in South Asian, white European and African Caribbean people with type 2 diabetes: A systematic review and meta-analysis.

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    AIMS: To conduct a systematic review and meta-analysis of published observational evidence to assess the difference in the prevalence and progression of diabetic nephropathy, and the development of end-stage renal disease (ESRD) in people from three different ethnic groups with type 2 diabetes (T2DM). MATERIALS AND METHODS: Relevant studies were identified in a literature search of MEDLINE, EMBASE and reference lists of relevant studies published up to May 2018. We decided a priori that there were no differences in the prevalence and progression of diabetic nephropathy, and the development of ESRD in the three ethnicities with T2DM. Pooled relative risks of microalbuminuria by ethnicity were estimated by fitting three random effects meta-analyses models. A narrative synthesis of the nephropathy progression in the studies was carried out. The review was registered in PROSPERO (CRD42018107350). RESULTS: Thirty-two studies with data on 153 827 unique participants were eligible for inclusion in the review. The pooled prevalence ratio of microalbuminuria in South Asian compared with white European participants was 1.14 (95% confidence interval [CI] 0.99, 1.32; P = 0.065), while for African Caribbean vs South Asian participants the pooled prevalence ratio was 1.08 (95% CI 0.93, 1.24; P = 0.327). Results for renal decline were inconsistent, with preponderance towards a high rate of disease progression in South Asian compared with white participants. The estimated pooled incidence rate ratio (IRR) for ESRD was significantly higher in African Caribbean vs white European participants: 2.75 (95% CI 2.01, 3.48; P < 0.001). CONCLUSION: The results of this review did not show a significant link between ethnicity (South Asian, white European and African Caribbean) and the prevalence of microalbuminuria; however, the IRR for ESRD in African Caribbean compared with white European participants was significantly higher. Further research is needed to explore the potential non-albuminuric pathways of progression to ESRD

    Challenges in creating dissectible anatomical 3D prints for surgical teaching

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    Three-dimensional (3D) printing, or additive manufacturing, is now a widely used tool in pre-operative planning, surgical teaching and simulator training. However, 3D printing technology that produces models with accurate haptic feedback, biomechanics and visuals for the training surgeon is not currently available. Challenges and opportunities in creating such surgical models will be discussed in this review paper. Surgery requires proper tissue handling as well as knowledge of relevant anatomy. To prepare doctors properly, training models need to take into account the biomechanical properties of the anatomical structures that will be manipulated in any given operation. This review summarises and evaluates the current biomechanical literature as it relates to human tissues and correlates the impact of this knowledge on developing high fidelity 3D printed surgical training models. We conclude that, currently, a printer technology has not yet been developed which can replicate many of the critical qualities of human tissue. Advances in 3D printing technology will be required to allow the printing of multi-material products to achieve the mechanical properties required

    Bio-nano Science: Better Metrics Would Accelerate Progress

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    An early step of evaluating a nanomaterial’s potential for biological applications is investigating its interactions with cells and biological fluids. These experiments generate complex data, which are summarized and analyzed through the use of metrics. Choosing appropriate metrics is thus critical to build a foundation for nanomaterial research. Unfortunately, several widely used metrics in the bio-nano scientific literature have significant issues and may not be delivering their intended insight. This perspective will label and discuss three problematic metrics in wide use within the field: Percentage Cell Association, used to measure the interaction strength between a cell and a nanoengineered material; Internalization Factor, used to measure the ability of a cell to internalize a nanoengineered system; and Detected Protein Abundance, used to analyze the composition of proteins that adsorb to a nanoengineered surface. We review the origin of each metric and explain why each fails to deliver the intended insight in the domain of bio-nano experiments. Finally, for each metric, we present alternative metrics that deliver the necessary insight while imposing little (or no) additional experimental burden. We hope that this perspective will increase the use of better metrics, improve reporting, and ultimately aid the transition of bio-nano science to a more quantitative field
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