https://hdl.handle.net/2123/8423 2026-06-04T13:16:57Z 2026-06-04T13:16:57Z Roffelsen, Pieter https://hdl.handle.net/2123/34244 2026-05-04T03:13:30Z 2025-08-21T00:00:00Z

Orbit data of q-difference Painlevé one over finite fields Roffelsen, Pieter This item includes data on orbit lengths of q-difference Painlevé one over finite fields as well as code used to generate and analyse it.

2025-08-21T00:00:00Z Cameron, Rosie https://hdl.handle.net/2123/33863 2025-08-01T05:01:22Z 2025-05-02T00:00:00Z

Focus group data: Instant feedback and mathematics self-efficacy Cameron, Rosie Transcripts from focus group discussions.

2025-05-02T00:00:00Z Lehrer, Gustav https://hdl.handle.net/2123/33819 2025-04-15T04:08:21Z 2025-01-01T00:00:00Z

Gordon Elliott (Tim) Wall, 11 March 1925–13 July 2023 Lehrer, Gustav G. E. (Tim) Wall was one of Australia’s leading algebraists, whose work intersected many of the important algebraic themes of his era (roughly 1960–95). This biographical memoir follows his life from his birth in 1925 in Adelaide, through his professional career, mostly at the University of Sydney, giving some details of his family, personal interactions and research.

2025-01-01T00:00:00Z Roberts, Lindon https://hdl.handle.net/2123/33803 2026-05-04T03:13:25Z 2025-01-01T00:00:00Z

Model Construction for Convex-Constrained Derivative-Free Optimization Roberts, Lindon We develop a new approximation theory for linear and quadratic interpolation models, suitable for use in convex-constrained derivative-free optimization (DFO). Most existing model-based DFO methods for constrained problems assume the ability to construct sufficiently accurate approximations via interpolation, but the standard notions of accuracy (designed for unconstrained problems) may not be achievable by only sampling feasible points, and so may not give practical algorithms. In this work, we demonstrate that linear regression models and underdetermined quadratic interpolation models (in the minimum Frobenius sense) can be made sufficiently accurate (in a sense appropriate for convex-constrained problems) using only feasible points. For the underdetermined quadratic interpolation case, we provide a simple procedure for constructing such feasible interpolation sets, providing a theoretical basis for practical and strictly feasible methods for constrained DFO.

2025-01-01T00:00:00Z Hare, Warren Roberts, Lindon Royer, Clément W. https://hdl.handle.net/2123/33625 2025-04-23T07:28:28Z 2025-01-01T00:00:00Z

Expected decrease for derivative-free algorithms using random subspaces Hare, Warren; Roberts, Lindon; Royer, Clément W. Derivative-free algorithms seek the minimum of a given function based only on function values queried at appropriate points. Although these methods are widely used in practice, their performance is known to worsen as the problem dimension increases. Recent advances in developing randomized derivative-free techniques have tackled this issue by working in low-dimensional subspaces that are drawn at random in an iterative fashion. The connection between the dimension of these random subspaces and the algorithmic guarantees has yet to be fully understood. In this paper, we develop an analysis for derivative-free algorithms (both direct-search and model-based approaches) employing random subspaces. Our results leverage linear local approximations of smooth functions to obtain understanding of the expected decrease achieved per function evaluation. Although the quantities of interest involve multidimensional integrals with no closed-form expression, a relative comparison for different subspace dimensions suggest that low dimension is preferable. Numerical computation of the quantities of interest confirm the benefit of operating in low-dimensional subspaces.

2025-01-01T00:00:00Z Bertram, C.D. Hancock, E.J. Macaskill, C. https://hdl.handle.net/2123/32566 2024-05-20T07:59:32Z 2024-05-20T00:00:00Z

RyRcode.zip Bertram, C.D.; Hancock, E.J.; Macaskill, C. A ZIP-file containing two Matlab m-files, constituting the code required to solve the equations listed in the paper "A model of pacemaker oscillations in lymphatic muscle cells: ryanodine receptor inclusion allows lengthened action potentials by two mechanisms"

2024-05-20T00:00:00Z Bertram, Christopher David https://hdl.handle.net/2123/32398 2024-03-20T23:35:38Z 2024-03-21T00:00:00Z

The lymphatic vascular system: does non-uniform lymphangion length limit flow-rate? Bertram, Christopher David The deposition consists of a ZIP-file containing data files in Matlab binary format containing the data plotted in Figures 3-8 and supplementary Figures S1-S10 of the paper 'The lymphatic vascular system: does non-uniform lymphangion length limit flow-rate?' by C.D. Bertram, published in 2024 in the ASME Journal of Biomechanical Engineering.

2024-03-21T00:00:00Z Hancock, Edward J. Macaskill, Charlie Bertram, Christopher D. https://hdl.handle.net/2123/31688 2023-09-19T23:19:14Z 2023-09-20T00:00:00Z

JGPcode.zip Hancock, Edward J.; Macaskill, Charlie; Bertram, Christopher D. ZIP-format file containing Matlab code for solution of the equations in the paper 'A dual-clock-driven model of lymphatic muscle cell pace-making to emulate knock out of Ano1 or IP3R', by Edward J. Hancock, Scott D. Zawieja, Charlie Macaskill, Michael J. Davis and Christopher D. Bertram, published in the Journal of General Physiology in 2023.

2023-09-20T00:00:00Z Allen, D.E. https://hdl.handle.net/2123/29110 2026-05-04T03:13:29Z 2022-01-01T00:00:00Z

Cryptocurrencies, Diversification and the COVID-19 Pandemic Allen, D.E. This paper features an analysis of cryptocurrencies and the impact of the COVID-19 pandemic on their effectiveness as a portfolio diversification tool and explores the correlations between the continuously compounded returns on Bitcoin, Ethereum and the S&P500 Index using a variety of parametric and non-parametric techniques. These methods include linear standard metrics such as the application of ordinary least squares regression (OLS) and the Pearson, Spearman and Kendall's tau measures of association. In addition, non-linear, non-parametric measures such as the Generalised Measure of Correlation (GMC) and non-parametric copula estimates are applied. The results across this range of measures are consistent. The metrics suggest that, whilst the shock of the COVID-19 pandemic does not appear to have increased the correlations between the cryptocurrency series, it appears to have increased the correlations between the returns on cryptocurrencies and those on the S&P500 Index. This suggests that investments in cryptocurrencies are not likely to offer key diversification strategies in times of crisis, on the basis of evidence provided by this crisis.

2022-01-01T00:00:00Z Nasreen, Zahra https://hdl.handle.net/2123/28387 2026-05-04T03:13:33Z 2022-01-01T00:00:00Z

The impact of the COVID-19 pandemic on tenants and operators in marginal housing forms: a reply to 'COVID-19 and precarious housing: paying guest accommodation in a metropolitan Indian city' by Marella et al Nasreen, Zahra

2022-01-01T00:00:00Z Allen, David E. McAleer, Michael https://hdl.handle.net/2123/28253 2026-05-04T03:13:24Z 2022-01-01T00:00:00Z

Trump's COVID-19 tweets and Dr. Fauci's emails Allen, David E.; McAleer, Michael The paper features an analysis of former President Trump's early tweets on COVID-19 in the context of Dr. Fauci's recently revealed email trove. The tweets are analysed using various data mining techniques, including sentiment analysis. These techniques facilitate exploration of content and sentiments within the texts, and their potential implications for the national and international reaction to COVID-19. The data set or corpus includes 159 tweets on COVID-19 that are sourced from the Trump Twitter Archive, running from 24 January 2020 to 2 April 2020. In addition we use Zipf and Mandelbrot's power law to calibrate the extent to which they differ from normal language patterns. A context for the emails is provided by the recently revealed email trove of Dr. Fauci, obtained by Buzzfeed on 1 June 2021 obtained under the Freedom of Information Act.

2022-01-01T00:00:00Z Yatim, S.A.M. Kim, P.S. https://hdl.handle.net/2123/26515 2026-05-04T03:13:25Z 2021-01-01T00:00:00Z

Effects of Movement Control Order on mitigating spread of COVID-19 in the early phase of the outbreak in Malaysia Yatim, S.A.M.; Kim, P.S. We propose a mathematical model to investigate the early outbreak of COVID-19 in Malaysia. The model emphasizes the role of the government's Movement Control Orders (MCOs) as population-wide lockdown measures and the potential benefit of mass testing on disease spread. We fit this model to the reported active COVID-19 cases to estimate model parameters. We also assume transmission rates change with respect to stages of MCOs and compare the differences in rates to assess the effectiveness of different levels of MCO restrictions. The estimated parameters match the observed data well, and our results suggest a slowing of the trajectory of COVID-19 outbreak in the country, indicating that the series of MCOs taken to counter COVID-19 transmission are having a significant positive effect.

2021-01-01T00:00:00Z Allena, D.E. McAleer, M. https://hdl.handle.net/2123/25832 2026-05-04T03:13:28Z 2021-01-01T00:00:00Z

Predicting COVID-19 Cases and Deaths in the USA from Tests and State Populations? Allena, D.E.; McAleer, M. School of Mathematics and Statistics, University of Sydney, Department of Finance, Asia University, Taiwan,The paper presents a novel analysis of the US spread of the SARS-CoV-2 causes the COVID-19 disease across 50 States and 2 Territories. Simple cross-sectional regressions are able to predict quite accurately both the total number of cases and deaths, which cast doubt on measures aimed at controlling the disease via lockdowns. Population density appears to play a significant role in transmission. This throws in sharp relief the relative e_ectiveness of the at-tempts to risk manage the spread of the virus by flattening the curve' (aka planking the curve) of the speed of transmission, and the effcacy of lockdowns in terms of the spread of the disease and death rates. The algorithmic tech-niques, results and analysis presented in the paper should prove useful to the medical and health professions, science advisers, and risk management and deficision making of healthcare by state, regional and national governments in all countries.

2021-01-01T00:00:00Z Fisher, Nicholas I. Trewin, Dennis J. https://hdl.handle.net/2123/25644 2026-05-04T03:13:32Z 2021-01-01T00:00:00Z

A proposal to enhance national capability to manage epidemics: The critical importance of expert statistical input including official statistics Fisher, Nicholas I.; Trewin, Dennis J. Given the high level of global mobility, pandemics are likely to be more frequent, and with potentially devastating consequences for our way of life. With COVID-19, Australia is in relatively better shape than most other countries and is generally regarded as having managed the pandemic well. That said, we believe there is a critical need to start the process of learning from this pandemic to improve the quantitative information and related advice provided to policy makers. A dispassionate assessment of Australia’s health and economic response to the COVID-19 pandemic reveals some important inadequacies in the data, statistical analysis and interpretation used to guide Australia’s preparations and actions. For example, one key shortcoming has been the lack of data to obtain an early understanding of the extent of asymptomatic and mildly symptomatic cases or the differences across age groups, occupations or ethnic groups. Minimising the combined health, social and economic impacts of a novel virus depends critically on ongoing acquisition, integration, analysis, interpretation and presentation of a variety of data streams to inform the development, execution and monitoring of appropriate strategies. The article captures the essential quantitative components of such an approach for each of the four basic phases, from initial detection to post-pandemic. It also outlines the critical steps in each stage to enable policy makers to deal more efficiently and effectively with future such events, thus enhancing both the social and the economic welfare of its people. Although written in an Australian context, we believe most elements would apply to other countries as well.

2021-01-01T00:00:00Z He J. Lin Y. Meng M. Li J. Yang J.Y.H. Wang H. https://hdl.handle.net/2123/25491 2026-04-22T03:37:06Z 2021-01-01T00:00:00Z

Construction of a human cell landscape of COVID-19 infection at single-cell level He J.; Lin Y.; Meng M.; Li J.; Yang J.Y.H.; Wang H. COVID-19 is now causing a global pandemic, there is a demand to explain the different clinical patterns between children and adults. To clarify the organs/cell types vulnerable to COVID-19 infection and the potential age-depended expression patterns of five factors (ACE2, TMPRSS2, MTHFD1, CTSL, CTSB) associated with clinical symptoms. In this study, we analyzed expression levels of five COVID-19 host dependency factors in multiple adult and fetal human organs. The results allowed us to grade organs at risk and also pointed towards the target cell types in each organ mentioned above. Based on these results we constructed an organ- and cell type-specific vulnerability map of the expression levels of the five COVID-19 factors in the human body, providing insight into the mechanisms behind the symptoms, including the non-respiratory symptoms of COVID-19 infection and injury. Also, the different expression patterns of the COVID-19 factors well demonstrate an explanation that the different clinical patterns between adult and children/infants.

2021-01-01T00:00:00Z Chin, Vincent Ioannidis, John P.A. Tanner, Martin A. Cripps, Sally https://hdl.handle.net/2123/24835 2026-05-04T03:13:28Z 2021-01-01T00:00:00Z

Effect Estimates of COVID-19 Non-Pharmaceutical Interventions are Non-Robust and Highly Model-Dependent Chin, Vincent; Ioannidis, John P.A.; Tanner, Martin A.; Cripps, Sally Objective: To compare the inference regarding the effectiveness of the various non-pharmaceutical interventions (NPIs) for COVID-19 obtained from different SIR models. Study design and setting: We explored two models developed by Imperial College that considered only NPIs without accounting for mobility (model 1) or only mobility (model 2), and a model accounting for the combination of mobility and NPIs (model 3). Imperial College applied models 1 and 2 to 11 European countries and to the USA, respectively. We applied these models to 14 European countries (original 11 plus another 3), over two different time horizons. Results: While model 1 found that lockdown was the most effective measure in the original 11 countries, model 2 showed that lockdown had little or no benefit as it was typically introduced at a point when the time-varying reproduction number was already very low. Model 3 found that the simple banning of public events was beneficial, while lockdown had no consistent impact. Based on Bayesian metrics, model 2 was better supported by the data than either model 1 or model 3 for both time horizons. Conclusions: Inferences on effects of NPIs are non-robust and highly sensitive to model specification. In the SIR modeling framework, the impacts of lockdown are uncertain and highly model dependent.

2021-01-01T00:00:00Z Duistermaat, Johannes (Hans) J. Joshi, Nalini https://hdl.handle.net/2123/8422 2026-05-04T03:04:17Z 2011-01-01T00:00:00Z

Okamoto's space for the first Painlevé equation in Boutroux coordinates Duistermaat, Johannes (Hans) J.; Joshi, Nalini We study the completeness and connectedness of asymptotic behaviours of solutions of the first Painlev ́e equation d^2 y/ dx^2 = 6 y^2 + x, in the limit x → ∞, x ∈ C. This problem arises in various physical contexts including the critical behaviour near gradient catastrophe for the focusing nonlinear Schrodinger equation. We prove that the complex limit set of solutions is non-empty, compact and invariant under the flow of the limiting autonomous Hamiltonian system, that the infinity set of the vector field is a repellor for the dynamics and obtain new proofs for solutions near the equilibrium points of the autonomous flow. The results rely on a realization of Okamoto’s space, i.e., the space of initial values compactified and regularized by embedding in CP2 through an explicit construction of nine blow-ups.

2011-01-01T00:00:00Z