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High-performance Electrolytes for Li-CO2 Batteries
No full textGlobal climate change caused by the rapid increase of carbon dioxide (CO2) emissions has stimulated intensive research on how to achieve CO2 conversion and utilization with high efficiency and low cost. Transformation of CO2 into other chemicals, accompanied by an additional energy input and possible environmental pollution, struggles to fully meet eco-efficient and environmentally sustainable demand. Rechargeable Li-CO2 batteries with high discharge potential (2.80 V vs. Li+/Li) and theoretical energy density (1876 Wh kg-1), based on the reversible redox reaction of 3CO2 + 4Li+ + 4e- ↔ 2Li2CO3 + C, provide a win-win solution to carbon neutrality and high-energy-density storage systems. In addition, it has been projected by NASA in the field of space exploration that uptake of Li-CO2 batteries would enable significant weight and cost savings for Mars exploration missions because 96% of the Martian atmosphere is CO2.Because of the sluggish CO2 reaction kinetics, however, and the presence of highly reactive *CO22- radicals during discharge, Li-CO2 batteries currently suffer from huge polarization potential, unstable electrode/electrolyte interfaces, and poor cyclability. Most previous efforts have been focused on bifunctional catalyst design for cathodes to reduce battery overpotential and protect lithium anode/cathode protection through electrolyte additives. Even so, the critical role of anions/solvents in the formation of a robust solid electrolyte interphase (SEI) layer on cathodes and the solvation structure have never been investigated.</p
Physical activity, sedentary behaviour and healthy eating in out of school hours care: an observational audit and pilot intervention
No full textBackgroundPromoting physical activity (PA) and healthy eating and limiting sedentary behaviour are important for the growth and development of children aged 5-12 years. Out of school hours care (OSHC) is a childcare setting which provides opportunities to promote child health behaviours, however, little is known about the health promoting environments of before school care settings. The aim of this thesis was, therefore, to better understand the PA, sedentary behaviour, and healthy eating environments of before school care; and promote healthy levels of these behaviours in OSHC services.MethodsThis thesis includes three studies which are presented as four research papers. Study one was a systematic review of the correlates of PA and sedentary behaviour in OSHC. Study two was a cross-sectional examination of the PA, sedentary behaviour and healthy eating environments of before school care programs. Study three used findings from the first two studies to co-create an OSHC intervention with stakeholders and end-users. The intervention was then pilot tested using a cluster randomised controlled trial (RCT) design.ResultsThe systematic review identified 18 cross-sectional studies reporting 116 PA and 64 sedentary behaviour correlates. The most frequently reported correlates of PA were child sex (males more active), staff engaging in PA, an absence of elimination games, and scheduling PA in daily programming. For sedentary behaviour the most frequently reported correlates were child sex (females more sedentary) and age (older children more sedentary).Study two included 49 observational visits across 25 before school care programs and collected accelerometry data for 654 child observation days. Child PA (accelerometry) data were analysed, and it was found that 17% of children (n = 112) reached the ≥ 15 minutes of moderate-to-vigorous intensity PA (MVPA) recommendation for before school care, with boys more active than girls. Children were more likely to meet the recommendation in services where staff promoted and engaged in PA; PA equipment was available; children were observed in child-led free play; and a written PA policy existed. Direct food observations showed that fruit was provided on 22% (n=11) of days and vegetables on 12% (n=6). Services with nutrition policies containing specific and measurable language on food provision were more likely to provide fruit (p = 0.027); and services that reported staff training for healthy eating provided more vegetables (p = 0.037).Study three focussed on the before and after school care programs of four OSHC services (intervention = 2 services; waitlist-control = 2 services). The co-created professional development program was found to be both feasible and acceptable. Post-intervention, there were no significant between group differences in changes in children meeting MVPA guidelines, however, small to medium effect sizes (d = 0.08 - 0.62) were detected. Frequency of fruit provision increased more in before school care intervention programs, and vegetables provision increased more in both before and after school care intervention programs.ConclusionsTo the candidate’s knowledge, this thesis is the first known research to assess the PA, sedentary behaviour and healthy eating environments of Australian before school care services; and to assess a co-created staff professional development program to improve these environments in OSHC services. The findings highlight modifiable practices at service and staff levels to improve child PA and healthy eating opportunities while attending OSHC. They also present a framework for a staff professional development program which is both feasible and acceptable. Larger intervention trials are recommended to further evaluate impacts on child PA and service food provision.</p
Essays on the Market Microstructure of Centralised and Decentralised Finance
No full textThis dissertation consists of three essays that examine trading costs and risks across two different market structures–centralised and decentralised finance–and the relationship between the two. The research provides empirical evidence on issues of increasing relevance for the trading of complex financial instruments such as derivatives and crypto-assets. Each essay addresses previously inconclusive research, offering insights for researchers, practitioners, and regulators to manage the costs and risks associated with trading in centralised and decentralised markets.The first essay examines the cost of trading large trades by reporting delays in centralised markets. Prior research left a significant gap in understanding the impact of delaying the information about large trades at the time they are reported. I contribute to both the theoretical framework and empirical literature by using a cleaner natural experiment in FTSE100 futures. The major finding is that reporting delays encourages informed trading and potentially increases information efficiency. This provides practical insights to regulators by suggesting a better market design for their exchanges and market participants, who are affected by the ability of informed traders to observe and anticipate price information in the block trading process.The second essay examines the cost of zero-fee trading in decentralised markets. There is a scarcity of empirical research on this issue, and I provide evidence contrasting prior theoretical studies. By using a cleaner natural experiment in Bitcoin spot pairs traded on Binance, I find evidence that such fees’ elimination encourages market makers to request higher premiums and discounts on limit orders, which in turn widens the bid-ask spread and, therefore, deteriorates liquidity. Notably, despite the removal of trading fees, total transaction costs increased for customers. This and the boost in the exchange market share raise concerns about price integrity and investors’ protection in the highly unregulated crypto environment. The study has significant implications for trading execution, risk management, and investment decision-making in crypto-asset markets and, therefore, should be relevant to regulators and policymakers interested in developing new Regulatory Technology (RegTech) solutions with computerised surveillance.The last essay examines trading risks in the relationship between centralised and decentralised finance. Specifically, it examines the extent to which the collapse of a traditional financial institution, a commercial bank holding investments in tokens, spreads microstructure contagion across digital markets. Prior literature finds no evidence of a meaningful impact the Silicon Valley Bank bankruptcy had on major financial markets and sectors. By applying a BEKK multivariate GARCH model to intraday data, I provide empirical evidence of volatility spillover effects across major stablecoins and Bitcoin, a market severely affected by the collapse. This essay links centralised and decentralised finance, showing the ways in which spillovers can occur between what seem to be separate realms of finance. The results of this research are, therefore, relevant to policymakers in both traditional and modern financial systems who are interested in avoiding the risk of financial contagion, as well as investors willing to defend their savings and balance their portfolios against market uncertainty.</p
CQUESST: A dynamical stochastic framework for predicting soil-carbon sequestration
No full textA document outlining the deterministic equations that underpin the RothC model. A document containing details about the dynamical model parameters. A document containing details of exploratory spatial data analyses undertaken to look for evidence of spatial structure in the soil-carbon measurements. A document containing details about the prior distributions used on the parameters in the Bayesian hierarchical model. A document outlining a sensitivity analysis performed on the prior distributions for key parameters in CQUESST. A document containing details of diagnostic tests performed on samples from Markov Chain Monte Carlo (MCMC) to indicate that chains are sampling from the stationary distribution and that samples provided good estimates of posterior distributions. Plots of prior and posterior distributions for parameters in CQUESST. A document containing a comparison of the results of CQUESST to those of simpler linear models. Code is available on GitHub at https://github.com/dpagendam/CQUESST and on the CSIRO Data Access Portal at https://doi.org/10.25919/rj6m-q614. A statistical framework we call CQUESST (Carbon Quantification and Uncertainty from Evolutionary Soil STochastics), which models carbon sequestration and cycling in soils, is applied to a long-running agricultural experiment that controls for crop type, tillage, and season. The experiment, known as the Millenium Tillage Trial (MTT), ran on 42 field-plots for 10 years from 2000–2010; here CQUESST is used to model soil carbon dynamically in six pools, in each of the 42 agricultural plots, and on a monthly time step for a decade. We show how CQUESST can be used to estimate soil-carbon cycling rates under different treatments. Our methods provide much-needed statistical tools for quantitatively inferring the effectiveness of different experimental treatments on soil-carbon sequestration. The decade-long data are of multiple observation types, and these interacting time series are ingested into a fully Bayesian model that has a dynamic stochastic model of multiple pools of soil carbon at its core. CQUESST’s stochastic model is motivated by the deterministic RothC soil-carbon model based on nonlinear difference equations. We demonstrate how CQUESST can estimate soil-carbon fluxes for different experimental treatments while acknowledging uncertainties in soil-carbon dynamics, in physical parameters, and in observations. An important outcome of our modeling is the inference of cropping-specific decay rates, with evidence suggesting that soil carbon decay-rates vary as a function of land management practices. CQUESST is implemented efficiently in the probabilistic programming language Stan using its MapReduce parallelization, and it scales well for large numbers of field-plots, using software libraries that allow for computation to be shared over multiple nodes of high-performance computing clusters.</p
Neural Parameter Estimation with Incomplete Data
No full textAdvancements in artificial intelligence (AI) and deep learning have led to
neural networks being used to generate lightning-speed answers to complex
questions, to paint like Monet, or to write like Proust. Leveraging their
computational speed and flexibility, neural networks are also being used to
facilitate fast, likelihood-free statistical inference. However, it is not
straightforward to use neural networks with data that for various reasons are
incomplete, which precludes their use in many applications. A recently proposed
approach to remedy this issue inputs an appropriately padded data vector and a
vector that encodes the missingness pattern to a neural network. While
computationally efficient, this "masking" approach can result in statistically
inefficient inferences. Here, we propose an alternative approach that is based
on the Monte Carlo expectation-maximization (EM) algorithm. Our EM approach is
likelihood-free, substantially faster than the conventional EM algorithm as it
does not require numerical optimization at each iteration, and more
statistically efficient than the masking approach. This research represents a
prototype problem that indicates how improvements could be made in AI by
introducing Bayesian statistical thinking. We compare the two approaches to
missingness using simulated incomplete data from two models: a spatial Gaussian
process model, and a spatial Potts model. The utility of the methodology is
shown on Arctic sea-ice data and cryptocurrency data.</p
A bundle of care interventions to improve self-management and quality-of-life of community dwelling patients living with indwelling urinary catheters
No full textBackground Living with an indwelling urinary catheter (IDC) can be a challenging and unexpected experience for patients, with some requiring long-term use. However, patients often lack adequate support in adjusting to life with an IDC and troubleshooting common catheter-related issues. Without appropriate education, patients frequently rely on readily available information or a trial-and- error approach to self-manage their catheters, which can lead to preventable complications and negatively impact their quality of life. IDC-related issues contribute to increased healthcare costs, preventable hospital presentations, unnecessary antibiotic use, and additional strain on an already overburdened healthcare system. The “Bundle-of-care interventions to improve self-management and quality-of-life of patients living with indwelling urinary catheters” (IQ-IDC) research project spawned from these increasing challenges experienced by patients and the care providers. Nurses are well-positioned to empower patients in effectively managing their IDCs by providing tailored education. However, due to a lack of awareness and confidence, nurses often focus primarily on clinical aspects of catheterisation, overlooking patients’ selfmanagement and psychosocial needs. Enhancing nurses’ knowledge and skills in delivering holistic care is crucial for minimising unnecessary hospital presentations and improving patient outcomes.Purpose The key objective of this doctoral component of the IQ-IDC project was to facilitate behavioural change among nurses by enhancing their Capability, Opportunity, and Motivation—the core components of the COM-B model—to enable them to deliver optimal care to patients with IDCs using digital technologies. This involved building their capabilities through education and training, creating opportunities through supportive systems and resources, and strengthening their motivation leading to the behaviour change required to transform their current practice.Methods To achieve the objective, a mixed method approach underpinned by the Capability, Opportunity, Motivation - Behaviour (COM-B) theoretical model was employed to develop, implement, and evaluate a co-designed intervention to enhance nurses’ knowledge and performance in supporting patients to self- manage their IDCs and prevent IDC-related problems. The progressive outputs of this study were reported in a series of peer-reviewed papers, which are: 1) A scoping review to understand the information needs of patients living with IDCs and the impact of existing educational interventions; 2) A systematic review to identify the subject matter, educational approaches and effectiveness of existing educational interventions for nurses regarding delivering optimum care to patients living with IDCs; 3) A study protocol outlining the IQ-IDC project’s rationale and methodology to ensure rigor, transparency and reproducibility; 4) Psychometric analysis of the Expanded Catheter Self-management (E-CSM) scale, detailing its development, psychometric evaluation in assessing essential aspects of urinary catheter self-management; 5) Psychometric testing of the Catheter Assessment, Management and Performance (CAMP) scale, describing its development, theoretical underpinnings, and effectiveness in detecting changes in nurses’ self-reported behaviour change following educational intervention; and 6) A co-design study evaluating the effectiveness of the spaced eLearning intervention delivered via a digital platform, assessing its impact on nurses', capability, opportunity, motivation and behaviour in I DC management.Results The scoping and systematic reviews in Papers 1 and 2 identified gaps in I DC selfmanagement education and highlighted the need to upskill nurses to provide optimal care. The reviews informed the development of the co-designed educational intervention (Protocol Paper), incorporating input from patients and nurses (Paper 3). Paper 4 and 5 revealed that the E-CSM and CAMP scales have strong psychometric properties demonstrating their usefulness in assessing patients’ self-management skills and nurses’ behaviour to support them. These scales provided a reliable tool of identifying educational needs and tailoring interventions for both groups.Finally, Paper 6 reported on the effects of the co-designed eLearning intervention for nurses delivered via the Qstream digital platform, using micro and spaced learning strategies and multimedia content to enhance engagement. Following the intervention, the composite mean knowledge score improved from 65.03 to 84.30 (pConclusion Outputs of this doctoral study included the development of a co-designed eLearning intervention that addresses knowledge and performance gaps in IDC management among nurses. Additionally, the E-CSM scale demonstrated effectiveness in predicting the IDC-related problems and supporting tailored interventions, while the CAMP scale provided a robust measure of nurses’ readiness and behaviour to improve their practice. Future studies may consider trialling these tools and the eLearning module in diverse clinical settings, including residential aged care facilities, and rural and remote area practice. By adopting participatory research methodologies and co-designing impactful interventions, this study provides valuable strategies to enhance outcomes for the patient, nurse, and healthcare system.</p
Co-constructing Career Progression: Identity Navigation of Women Academics and the Role of Decision-makers in STEM Academia
No full textThe abstract for this item has not been populated.</p
Maritime Port Geographies: Materiality, Labour, and Statecraft in Global Crisis Context
No full textThis paper surveys geographical research on ports, and traces three emerging directions: materiality, maritime labour, and statecraft. Amidst the rescaling of global value chains, the fragmentation of production, the rise of cargo-mobilities and accompanying labour regimes, researchers have emphasised containerisation, the rise of logistical systems, and the power of lead shipping firms in driving port interchangeability. Yet, multiple crises and challenges—climate change, pandemic disruptions, decarbonisation, geopolitical conflict, trade wars—impact both global shipping and the ports that sustain global capitalism. Furthermore, such crises widen the scope of research beyond the archetypal container port: to heterogeneous, mixed commodity ‘dirty’ ports of varying sizes and degrees of specialisation. In surveying the literature on maritime ports facilitating circulations of diverse materials and commodities, themes of materiality, maritime labour, and statecraft highlight the different, evolving roles played by ports in a crisis-ridden context. Not merely interchangeable nodes in speeded-up flows, ports are variously environmentally risky places; strategic sites for distributing the heterogeneous materials needed for decarbonisation and globalised production; spaces of regulation, enforcement and conflict; and infrastructural projections of state power—bargaining chips in geopolitical deal-making. Geographers are well-positioned to contribute distinctive insights into how diverse commodities, capital, and people are made to circulate through maritime ports to places beyond, and with what effects.</p
Discovery and Clinical Utility of Novel Prognostic Biomarkers in Gastroesophageal Cancer
No full textGastric, gastroesophageal junction, and oesophageal adenocarcinomas are amongst the most common and lethal cancers. Biomarkers of cancer are vital for prognostication of patient survival, prediction of response to treatment, and allow for a better understanding of tumour progression through a treatment course. Understanding clinical biomarkers could allow for novel treatment targets to be identified, or re-utilisation of current therapeutics. This thesis investigates known and potential new molecular and clinical biomarkers of gastroesophageal cancers and further assesses their clinical relevance.Chapter 1 introduces gastric, gastroesophageal junction and oesophageal adenocarcinomas (GOCs), focusing on current clinically relevant and experimental biomarkers explored in this thesis. Background information is provided on the urokinase plasminogen activator system (uPAS), epithelial to mesenchymal transition (EMT), human epidermal growth factor receptor 2 (HER2), tumour budding (TB) and the effects of patient nutrition status on GOCs.Chapter 2 details the uPAS, a proteolytic pathway resulting in the remodelling of extracellular matrices facilitating tumour invasions and metastasis. This includes an up-to-date review of the clinical relevance of uPAS in GOCs. uPAS activity is demonstrated widely in GOCs and is associated with adverse tumour features, poorer patient survival and has a potential role as both a circulating biomarker and therapeutic target.Tumour budding (TB) is a novel pathological predictive biomarker. Chapter 3 describes TB in a local cohort of GOC patients by histological and immunohistochemical investigation. Patients with GOC and high levels of TB are associated with a shorter disease-free survival, confirming previous findings with other GOC patient cohorts globally. For the first time, the expression of the urokinase plasminogen activator receptor (uPAR) and E-cadherin was explored on tumour buds (TBs) directly and each was independently shown to have prognostic potential. A novel score combining uPAR and E-cadherin identifying TBs with a mesenchymal-like phenotype (denoted as TBmes) was shown to be an independent GOC prognostic biomarker, better at detecting high risk patients than standard TB enumeration, or sole evaluation of uPAR or E-cadherin TB expression. The fact that TBmes are strongly associated with poor prognosis also enhances our understanding of the underlying mechanism of TB formation and the role of TBs in GOC metastasis. This paradigm is then explored more broadly within the tumour invasion front (Chapter 3 appendix), where the EMT status of tumour cells is also a strong prognostic factor of GOCs.Cancers demonstrate heterogeneity, changing over the patient’s cancer journey. Novel methods are required to more readily identify cancer progression, tumour treatment resistance and patient prognosis. In Chapter 4 human peripheral blood mononuclear cells (PBMCs) from patients with GOC and from healthy individuals were analysed for uPAR expression by comprehensive multicolour flow cytometry. Confirming earlier findings in other pathologies, the proportion of uPAR positive cells was greater than 90% of all monocytes (with significant differences seen between monocyte subsets from GOC) and less than 1% of all CD3+ T-lymphocytes across both cohorts. However, a significantly increased proportion of uPAR positive T-lymphocytes was observed in GOC patients compared to those from healthy individuals. This novel finding was associated with shorter time to radiological progression than low uPAR expressing T-lymphocytes in patients with metastatic GOC. PBMC uPAR expression was also explored in a cohort of head and neck cancer patients undergoing curative treatment (Chapter 4 appendix) for comparison to the GOC cohort.HER2 is a well-established biomarker of GOC, offering both prognostic and predictive information, including for standard therapeutic options. In Chapter 5, the association between HER2 expressing GOCs and the development of brain metastasis is established, demonstrating that patients with HER2 positive tumours have a higher rate of brain metastasis. This strongly suggests that patients with HER2 expression should be considered for additional brain imaging and an aggressive approach to their brain metastasis management.Chapter 6 explores the impact of the nutritional status of GOC patients in the peri-operative setting. There is often a significant delay in the diagnosis of GOCs, which adversely affects the baseline nutrition of patients. Pre-operative malnutrition is multifactorial, including but not limited to cancer related cachexia and mechanical obstruction, and can be further compounded by anti-cancer treatments. We demonstrate that changes in patient nutrition over the pre-operative period result in poorer patient survival. Two methods of assessing GOC patient malnutrition, reduction in weight loss and the clinically validated patient generated subjective global assessment, are associated with worse survival outcomes. The study demonstrates the important need to improve peri-operative nutrition for the long-term survival of patients.Chapter 7 addresses the main finding established in each chapter, synthesises this information within the current literature and identifies potential future research opportunities.</p
The Impact of Peri-Operative Nutritional Status on Survival in Gastroesophageal Adenocarcinoma
No full textIn patients with gastric, gastroesophageal junction or esophageal adenocarcinoma (GOC), peri-operative multimodal therapies have improved survival; however, prognosis remains underwhelming. Pre-operative nutritional decline and weight are linked with poorer patient outcomes. This study retrospectively analyzed the impact of peri-operative nutritional status (as assessed by patient-generated subjective global assessment, PG-SGA), and weight loss on the survival of patients undergoing curative surgery for GOC (2013 to 2022). Of the 148 patients who underwent surgery, PG-SGA and weight data were available for 107 (72%) and 121 (82%), respectively. At presentation, 44% (n = 47) of patients were well nourished, dropping to 17% (n = 18) post-operatively. Lower post-operative nutritional status correlated to worse overall survival (OS) (p 10%) was ubiquitously observed in 54% (n = 64) of patients, and this group had shorter OS (HR: 2.2; 95%CI: 1.2–4.1; p = 0.009). In conclusion, both nutritional decline and weight loss negatively impacted survival. Maintenance of nutritional status over the peri-operative period resulted in better outcomes. This study highlights the need for improved nutritional support during curative treatment in GOC.</p