Journal articles on the topic 'Dividends Australia Mathematical models'
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1
Klein, R. "An unified approach to meteorological modelling based on multiple-scales asymptotics." Advances in Geosciences 15 (March 18, 2008): 23–33. http://dx.doi.org/10.5194/adgeo-15-23-2008.
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Abstract. In 2003, the author suggested a mathematical framework for the derivation of reduced meteorological models at a Mathematics conference (5th ICIAM, Sydney, Australia), (Klein, 2004). The framework consists of (i) non-dimensionalization of the 3-D compressible flow equations on the rotating sphere, (ii) identification of universal non-dimensional parameters, (iii) distinguished limits between these and additional problem-specific parameters, and (iv) multiple scales expansions in the remaining small parameter ε. This parameter may be interpreted as the cubic root of the centripetal acceleration due to the Earth's rotation divided by the acceleration of gravity, see also Keller (1951), Eq. (10). For the mojority of reduced models of theoretical meteorology that we have come across, the approach allowed us to generate systematic derivations starting directly from the 3-D compressible flow equations on the rotating sphere. The framework's potential fully shows in multiscale interaction studies such as Klein (2006), in which we incorporated bulk microphysics closures for moist processes and derived scale interaction models for deep convection. Currently, we study the structure, evolution, and motion of Hurricane strength H1/H2 vortices (Mikusky, 2007), large-scale stratocumulus cloud decks, and planetary-synoptic scale interaction models which should be relevant for Earth System Models of Intermediate Complexity (EMICs). Here we summarize the general framework and use the example of quasi-geostrophic theory to demonstrate its application.
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Copper, J. K., and A. B. Sproul. "Comparative study of mathematical models in estimating solar irradiance for Australia." Renewable Energy 43 (July 2012): 130–39. http://dx.doi.org/10.1016/j.renene.2011.11.050.
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Amir, Rabah, Igor V. Evstigneev, Thorsten Hens, Valeriya Potapova, and Klaus R. Schenk-Hoppé. "Evolution in pecunia." Proceedings of the National Academy of Sciences 118, no. 26 (June 25, 2021): e2016514118. http://dx.doi.org/10.1073/pnas.2016514118.
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The paper models evolution in pecunia—in the realm of finance. Financial markets are explored as evolving biological systems. Diverse investment strategies compete for the market capital invested in long-lived dividend-paying assets. Some strategies survive and some become extinct. The basis of our paper is that dividends are not exogenous but increase with the wealth invested in an asset, as is the case in a production economy. This might create a positive feedback loop in which more investment in some asset leads to higher dividends which in turn lead to higher investments. Nevertheless, we are able to identify a unique evolutionary stable investment strategy. The problem is studied in a framework combining stochastic dynamics and evolutionary game theory. The model proposed employs only objectively observable market data, in contrast with traditional settings relying upon unobservable investors’ characteristics (utilities and beliefs). Our method is analytical and based on mathematical reasoning. A numerical illustration of the main result is provided.
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Rodriguez, Daniel F., Ali Malik, Nasser I. Abumustafa, and Arshad Jamal. "Explanatory Power of Selected Proxies in Predicting Stock Returns of Large U.K. Companies." International Journal of Business and Management 14, no. 4 (March 8, 2019): 72. http://dx.doi.org/10.5539/ijbm.v14n4p72.
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Predicting stock returns has been instrumental in our understanding of capital market structure. The validity of models, like the Capital Asset Pricing Model or the Gordon Growth Model, has influenced and contributed to building mathematical representations in predicting required return. Several studies attempted to explore different variables to determine the explanatory power of proxies in predicting stock return. For example, it is reported that dividends can explain up to 25% of the variance in returns. The explanatory power of dividends in the regression analysis showed a significant variation when the analysis follows time-series methodology. This study aims at examining the predicting power in the U.K. equity market by plugging into the regression model some of the variables conventionally measured in the Structural Equation Modeling. The study is quantitative and uses secondary data. The findings of this study suggest that the selected proxies, dividend growth, earnings per share, and beta exhibit weak explanatory power in predicting returns of large U.K. companies.
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Yarram, Subba Reddy. "Corporate governance ratings and the dividend payout decisions of Australian corporate firms." International Journal of Managerial Finance 11, no. 2 (April 7, 2015): 162–78. http://dx.doi.org/10.1108/ijmf-01-2013-0012.
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Purpose – The purpose of this paper is to examine the influence of corporate governance on the dividend payout decisions of Australian firms by considering two related objectives. First, it considers the role of corporate governance ratings (CGRs) on the decision to pay or not to pay dividends. Second, it considers the influence of CGRs on the average dividend payout level of Australian firms. Design/methodology/approach – The sample consists of 413 non-financial firms included in the All Ordinaries Index for the period 2004-2009. A logit model is employed to analyse the decision to pay or omit dividends. Similarly, tobit method is employed to analyse the factors influencing the dividend payout level of Australian firms. To control for unobserved heterogeneity, this study employs random effects panel logit and panel tobit models. Findings – This study finds that CGRs have a significant positive influence on the decision to pay dividends and on the average dividend payout level of Australian firms. Similarly, the present study finds support for signalling hypothesis as profitability has a significant positive influence and a loss dummy has a significant negative influence on the dividend payout decisions of Australian firms. The study also finds support for the life cycle hypothesis as growth opportunities have a significant negative impact on the average dividend payout level of Australian firms. This study finds no conclusive evidence of the existence of dividend tax clientele in Australia. Research limitations/implications – Dividends provide a complementary governance role consistent with the “outcomes model” of the agency cost theory as proposed by La Port et al. (2000). Practical implications – The findings have implications for corporate governance policies. Principle-based governance mechanisms work as well as the rule-based governance mechanisms in an environment characterized by high levels of investor protection and well-developed stock markets. Companies that are well governed may limit the opportunities for managers to expropriate shareholders and thus governance may reduce the contracting costs associated with compensation policies. Originality/value – This is the first study that examines the influence of governance on dividend policy using the CGRs developed by the WHK Horwath/University of Newcastle. Findings are robust and account for unobserved heterogeneity as random effects panel models are employed.
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Kowerski, Mieczysław. "The Geographical, Economic and Legal Regionalization of the Changes in Dividend Payments in the World." Barometr Regionalny. Analizy i Prognozy 18, no. 1 (September 14, 2022): 39–65. http://dx.doi.org/10.56583/br.722.
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The dynamic growth of nominal and real values of dividends paid in the world, observed since the last quarter of the twentieth century, is determined by the companies with the largest capitalization. However, the increase in global dividend payments is not the same in all countries and is subject to geographical, economic and legal regionalization. It is also disturbed by economic fluctuations (especially the 2008 crisis) and, more recently, by the COVID-19 pandemic. The paper, using the data from the survey of Janus Henderson Investments, analyses changes in dividend payments in geographical (continents) economic (countries with a similar level of economic development) and legal (countries with similar legal systems) regions by the 1,200 largest companies in the world between 2009 and 2021. Linnear trend models taking into account the COVID-19 pandemic in the world and in separate regions and subregions, as well as the panel partial adjustment model of dividends vs. GDP, were estimated. The conducted research confirmed the impact of different forms of regionalization on the rate of dividend payments by the world’s largest companies. In the years 2009–2021 dividend payments in Australia and Asia grew the fastest. COVID-19 significantly reduced dividend payments in 2020 in Europe. Dividend payments in emerging markets countries grew faster than in developed markets countries and COVID-19 did not significantly reduce payouts on emerging markets. However, it is the developed markets that still provide the vast majority of dividends. The common law system is more favorable to dividend payments.
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Klepikova, O., J. Danylchuk, and T. Zagray. "Information and analytical technologies in trading enterprise management." 101, no. 101 (December 30, 2021): 113–23. http://dx.doi.org/10.26565/2311-2379-2021-101-11.
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The article considers economic and mathematical methods and information technologies for managing the processes of trade enterprise. Economic and mathematical models for solving warehousing logistics problems, stochastic and statistical models of inventory management, models of optimal management and queuing systems are analyzed. Flexible tools are used to increase the efficiency of trade enterprise management and timely decision-making. The tools combine the use of mathematical models, a simulation model and information-analytical technologies. The study was carried out in three stages. The simulation model is designed in the software iThink. The simulation model was used to forecast sales, incomes, expenses and profit, processes of goods purchases, which take into account the factors of seasonality and the rest of production both in a warehouse and in the enterprise as a whole. The efficiency indicators of the enterprise are calculated and the possibility of payroll depending on income and dividends to owners is analyzed. An investment project has been designed in the software «Alt-Invest». This project analyzes the possibility of opening a new store with regard for financial activities, the development of a business plan for an investment project, the preparation of financial feasibility study, and the assessment of the impact of external factors and internal parameters on the overall effectiveness of the project. A comparative assessment is carried out in order to select the most promising project option. ABC-XYZ scenario was designed in the software platform Loginom. Using this analysis, the product range was divided into groups depending on the revenue and financial capabilities of the enterprise.
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Lee, S. H., S. Vigneswaran, and K. Bajracharya. "Phosphorus transport in saturated slag columns: experiments and mathematical models." Water Science and Technology 34, no. 1-2 (July 1, 1996): 153–60. http://dx.doi.org/10.2166/wst.1996.0367.
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Excessive phosphorus (P as orthophosphate) is one of the major pollutants in natural water that are responsible for algal blooms and eutrophication. P removal by slag is an attractive solution if the P sorption capacity of slag is significant. To design an efficient land treatment facility, basic information on the behaviour of P in the media-water environment is required. In this study, detailed column experiments were conducted to study the P transport under dynamic condition, and mathematical models were developed to describe this process. The column experiments conducted with dust and cake waste products (slag) from a steel industry as adsorbing indicated that they had higher sorption capacity of P than that of a sandy loam soil from North Sydney, Australia. P transport in the dust and cake columns exhibited characteristic S-shaped or curvilinear breakthrough curves. The simulated results from a dynamic physical nonequilibrium sorption model (DPNSM) and Freundlich isotherm constants satisfactorily matched the corresponding experimental breakthrough data. The mobility of P is restricted by the adsorbents and it is proportional to the sorption capacity of them.
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Razali, K., J. Amin, GJ Dore, MG Law, and HCV Projections Working Group. "Modelling and calibration of the hepatitis C epidemic in Australia." Statistical Methods in Medical Research 18, no. 3 (November 26, 2008): 253–70. http://dx.doi.org/10.1177/0962280208094689.
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Hepatitis C virus (HCV) infection in Australia is predominantly transmitted through injecting drug use. A reduction in the heroin supply in Australia in late 2000 and early 2001 may have impacted the number of injecting drug users (IDUs) and the number of new hepatitis C infections. This paper updates estimates of HCV incidence between 1960 and 2005 and models long-term sequelae from infection. Outcomes among those with HCV were also recently assessed in a linkage study assessing cancer and causes of death following HCV diagnosis in New South Wales. Linkage study outcomes have been used here to calibrate modelled outcomes. Mathematical models were used to estimate HCV incidence among IDUs, migrants to Australia from high HCV-prevalence countries, and other HCV exposure groups. Recent trends in numbers of IDUs were based on indicators of injecting drug use. A natural history of HCV model was applied to estimate the prevalence of HCV in the population. Model predicted endpoints that were calibrated against the NSW linkage data over the period 1995—2002 were: (i) incident hepatocellular carcinoma (HCC); (ii) opioid overdose deaths; (iii) liver-related deaths; and (iv) all-cause mortality. Modelled estimates and the linkage data show reasonably good calibration for HCC cases and all-cause mortality. The estimated HCC incidence was increased from 70 cases in 1995 to 100 cases in 2002. All-cause mortality estimated at 1000 in 1995 increased to 1600 in 2002. Comparison of annual opioid deaths shows some agreement. However, the models underestimate the rate of increase observed between 1995 and 1999 and do not entirely capture the rapid decrease in overdose deaths from 2000 onwards. The linkage data showed a peak of overdose deaths at 430 in 1999 compared to 320 estimated by the models. Comparison of observed liver deaths with the modelled numbers showed poor agreement. A good agreement would require an increase in liver deaths from the assumed 2 to 5% per annum following cirrhosis in the models. Mathematical models suggest that HCV incidence decreased from a peak of 14,000 infections in 1999 to 9700 infections in 2005, largely attributable to a reduction in injecting drug use. The poor agreement between projected and linked liver deaths could reflect differing coding of causes of deaths, underestimates of the numbers of people with cirrhosis following HCV, or underestimates of rates of liver death following cirrhosis. The reasonably good agreement between most of the modelled estimates with observed linkage data provides some support for the assumptions used in the models.
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Markova, Olga Mikhailovna. "Application of mathematical modeling in creating investment portfolio of commercial bank." Vestnik of Astrakhan State Technical University. Series: Economics 2019, no. 4 (December 16, 2019): 112–19. http://dx.doi.org/10.24143/2073-5537-2019-4-112-119.
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The article touches upon the most urgent problem of creating the stock portfolio
of a commercial bank, where studying the strategies and tools of the bank’s investment activity and using mathematical models for its assessment help to identify the relationship between profitability and the risk of investing in securities. As a result of applied analysis and modeling of the portfolio structure, the optimal portfolio option is selected, which corresponds to a given level of risk and profitability, as well as to the investment strategy chosen by the bank. There has been analyzed the portfolio structure with specified characteristics of risk and profitability, according to the statistics of previous years. The types of documents have been systematized according to the compliance with the strategy of managing the portfolio of profitability growth, liquidity and risk minimization. Using the models of Markowitz, Tobin and other researchers of probabilistic portfolio assessment through covariance indicators and a correlation coefficient, there have been found the values of return on assets that can change in one direction or have a multidirectional nature, and allow to calculate dependence between the values of return on securities in the portfolio. There have been considered the following models: a portfolio model based on calculating the level of stock returns of LUKOIL JSC, Novatek JSC, Yandex; a portfolio model that includes risk-free assets with the highest level of reliability (government short-term bonds, federal loan bonds); capital asset pricing model which describes dependency between the risk and the required profitability. Based on these calculations there has been inferred the possibility of developing specific areas of the banking business in the field of securities transactions, including: saving funds (providing protection against inflation); capital growth (focus on the securities that have the potential for growth in market value); profitability (purchasing securities in order to obtain dividends on shares and interest on debt securities); liquidity (investments into financial tools that can be sold at any time at favorable prices); risk minimization. The results of the conducted analysis of correlation and regression of the securities portfolio have revealed the most preferred types of securities for growing profitability that are in the bank's portfolio: shares of the Russian oil company LUKOIL, the Russian gas company Novatek, Yandex cIA, as well as the federal loan bonds (based on the terms of calculating history dynamics since May 1, 2018 up to May 1, 2019)
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LAKSMI, PUTU IKA OKTIYARI, KOMANG DHARMAWAN, and LUH PUTU IDA HARINI. "PERAMALAN KUNJUNGAN WISATAWAN MENGGUNAKAN MODEL ARMAX DENGAN NILAI KURS DAN EKSPOR-IMPOR SEBAGAI FAKTOR EKSOGEN." E-Jurnal Matematika 3, no. 4 (November 28, 2014): 138. http://dx.doi.org/10.24843/mtk.2014.v03.i04.p076.
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Forecasting is science to estimate occurrence of the future. This matter can be conducted by entangling intake of past data and place to the next period with a mathematical form. This research aims to estimate the number of foreign tourists visiting Bali models using autoregressive moving average exogenous (ARMAX). The data used in this study is the number of tourists in Australia and the number of tourists in the RRC as a variable Y, and foreign currency exchange rate AUD, Chinese Yuan, and Export Import as the X factor from the period July 2009 to July 2014. In the analysis can be obtained in the best ARMAX models of the number of tourists in Australia is ARMAX(1,2,2) and the best model of the number of tourists in the RRC does not exist because the data for the ARMAX model parameters tourists no significant RRC.
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Lau, Henry. "Monitoring Quality of Components by Fuzzy Control Principle." International Journal of Reliability, Quality and Safety Engineering 05, no. 02 (June 1998): 133–45. http://dx.doi.org/10.1142/s0218539398000145.
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A fuzzy expert system uses fuzzy logic control,1 which is based on a "superset" of Boolean logic that has been extended to handle the concept of "partial truth." It replaces mathematical models with models that are built from a number of rules with fuzzy variables such as output temperature, and fuzzy terms such as extremely hot, fairly cold. A fuzzy expert system has been implemented in a plastic moulding shop in Australia for monitoring dimensional quality of output products. Because these plastic parts are used as assembly components for production of gear boxes, their dimensional accuracy is of utmost importance. This paper presents the implementation of this monitoring system adopting a graphical and non-mathematical approach, and examines the application of fuzzy control systems in quality control. Practical examples with descriptions of how the fuzzy rules are shown and the operations of the fuzzy inference engine are covered.
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Law, Helen. "Why do adolescent boys dominate advanced mathematics subjects in the final year of secondary school in Australia?" Australian Journal of Education 62, no. 2 (July 23, 2018): 169–91. http://dx.doi.org/10.1177/0004944118776458.
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In Australia, many students, especially girls, choose not to study advanced mathematics in Year 12 even though their schools offer relevant subjects. Previous studies have rarely examined, using nationally representative samples of Australian students, the extent to which teenage educational experiences and occupational expectations influence gender differences in later pursuits of advanced mathematics subjects. To fill this gap, I use multilevel logistic regression models to analyse the data from the 2003 cohort of the Longitudinal Survey of Australian Youth. My results show that students’ mathematics achievement, occupational expectations and self-assessed mathematical competence are crucial in explaining why boys are considerably more likely than girls to enrol in advanced mathematics subjects. The gender gap would decrease greatly if girls were as likely as boys to perform well in mathematics, to aspire to mathematically intensive careers and to have more confidence in their mathematical abilities when they were 15 years old.
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Benke, Kurt K., and Nathan J. Robinson. "Quantification of Uncertainty in Mathematical Models: The Statistical Relationship between Field and Laboratory pH Measurements." Applied and Environmental Soil Science 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/5857139.
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The measurement of soil pH using a field portable test kit represents a fast and inexpensive method to assess pH. Field based pH methods have been used extensively for agricultural advisory services and soil survey and now for citizen soil science projects. In the absence of laboratory measurements, there is a practical need to model the laboratory pH as a function of the field pH to increase the density of data for soil research studies and Digital Soil Mapping. The accuracy and uncertainty in pH field measurements were investigated for soil samples from regional Victoria in Australia using both linear and sigmoidal models. For samples in water and CaCl2 at 1 : 5 dilutions, sigmoidal models provided improved accuracy over the full range of field pH values in comparison to linear models (i.e., pH < 5 or pH > 9). The uncertainty in the field results was quantified by the 95% confidence interval (CI) and 95% prediction interval (PI) for the models, with 95% CI < 0.25 pH units and 95% PI = ±1.3 pH units, respectively. It was found that the Pearson criterion for robust regression analysis can be considered as an alternative to the orthodox least-squares modelling approach because it is more effective in addressing outliers in legacy data.
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Robson, Edward, and Vinayak V. Dixit. "Constructing a Database for Computable General Equilibrium Modeling of Sydney, Australia, Transport Network." Transportation Research Record: Journal of the Transportation Research Board 2606, no. 1 (January 2017): 54–62. http://dx.doi.org/10.3141/2606-07.
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In the search for benefits to justify transport projects, economic appraisals have increasingly incorporated the valuation of impacts to the wider economy. Computable general equilibrium (CGE) models provide a framework to estimate these impacts by simulating the interactions of urban economies and transport networks. In CGE models, households and firms are represented by microeconomic behavioral functions, and markets adjust according to prices. As markets both inside and outside the transport network are taken into account, a wide variety of measures that can assist in economic appraisals can be extracted. However, urban CGE models are computationally burdensome and require detailed, spatially disaggregate data. This paper discusses the methodology used to develop a database, including an input–output table, for the calibration of an urban CGE model for Sydney, Australia. Official and publicly available data sources were manipulated by using a number of mathematical and statistical techniques to compile a table for 249 regions and 20 sectors across Sydney. Issues, such as determining the appropriate level of aggregation, generating incomplete data, and managing conflicting data, that other input–output table developers may encounter when constructing multiregional tables were addressed in the study. The table entries themselves were mapped and explored, as they provide a useful study of the spatial economy of Sydney. Future work will focus on streamlining the construction of input–output tables and incorporating new data sources.
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Robin, Libby. "Uncertain Seasons in the El Niño Continent: Local and Global Views." Australia, no. 28/3 (January 15, 2019): 7–19. http://dx.doi.org/10.7311/0860-5734.28.3.02.
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As global climate change shifts seasonal patterns, local and uncertain seasons of Australia have global relevance. Australia’s literature tracks extreme local weather events, exploring ‘slow catastrophes’ and ‘endurance.’ Humanists can change public policy in times when stress is a state of life, by reflecting on the psyches of individuals, rather than the patterns of the state. ‘Probable’ futures, generated by mathematical models that predict nature and economics, have little to say about living with extreme weather. Hope is not easily modelled. The frameworks that enable hopeful futures are qualitatively different. They can explore the unimaginable by offering an ‘interior apprehension.’
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Rahimi, Iman, Amir H. Gandomi, Panagiotis G. Asteris, and Fang Chen. "Analysis and Prediction of COVID-19 Using SIR, SEIQR, and Machine Learning Models: Australia, Italy, and UK Cases." Information 12, no. 3 (March 3, 2021): 109. http://dx.doi.org/10.3390/info12030109.
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The novel coronavirus disease, also known as COVID-19, is a disease outbreak that was first identified in Wuhan, a Central Chinese city. In this report, a short analysis focusing on Australia, Italy, and UK is conducted. The analysis includes confirmed and recovered cases and deaths, the growth rate in Australia compared with that in Italy and UK, and the trend of the disease in different Australian regions. Mathematical approaches based on susceptible, infected, and recovered (SIR) cases and susceptible, exposed, infected, quarantined, and recovered (SEIQR) cases models are proposed to predict epidemiology in the above-mentioned countries. Since the performance of the classic forms of SIR and SEIQR depends on parameter settings, some optimization algorithms, namely Broyden–Fletcher–Goldfarb–Shanno (BFGS), conjugate gradients (CG), limited memory bound constrained BFGS (L-BFGS-B), and Nelder–Mead, are proposed to optimize the parameters and the predictive capabilities of the SIR and SEIQR models. The results of the optimized SIR and SEIQR models were compared with those of two well-known machine learning algorithms, i.e., the Prophet algorithm and logistic function. The results demonstrate the different behaviors of these algorithms in different countries as well as the better performance of the improved SIR and SEIQR models. Moreover, the Prophet algorithm was found to provide better prediction performance than the logistic function, as well as better prediction performance for Italy and UK cases than for Australian cases. Therefore, it seems that the Prophet algorithm is suitable for data with an increasing trend in the context of a pandemic. Optimization of SIR and SEIQR model parameters yielded a significant improvement in the prediction accuracy of the models. Despite the availability of several algorithms for trend predictions in this pandemic, there is no single algorithm that would be optimal for all cases.
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White, DH, and PJ Bowman. "Economics of feeding energy-based supplements to grazing ewes before mating in order to increase the reproduction rate of a wool-producing flock." Australian Journal of Experimental Agriculture 27, no. 1 (1987): 11. http://dx.doi.org/10.1071/ea9870011.
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The financial wisdom of feeding energy-based supplements to ewes before mating to increase fecundity was evaluated using mathematical models of sheep production systems. It was concluded that, for a wool-producing enterprise in southern Australia, feeding supplements to ewes pre-mating is likely to be highly unprofitable. This is partly because relatively few ewes would have extra ova and also because multiple embryos and lambs have a lower probability of survival than single embryos and lambs. Further more, the extra lambs reared would be associated with an increase in grazing pressure which would necessitate a reduction in either stocking rate or in ewe liveweight at mating and thus fecundity in the subsequent season.
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REGAN, D. G., J. G. WOOD, C. BENEVENT, H. ALI, L. WATCHIRS SMITH, P. W. ROBERTSON, M. J. FERSON, C. K. FAIRLEY, B. DONOVAN, and M. G. LAW. "Estimating the critical immunity threshold for preventing hepatitis A outbreaks in men who have sex with men." Epidemiology and Infection 144, no. 7 (November 13, 2015): 1528–37. http://dx.doi.org/10.1017/s0950268815002605.
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SUMMARYSeveral outbreaks of hepatitis A in men who have sex with men (MSM) were reported in the 1980s and 1990s in Australia and other countries. An effective hepatitis A virus (HAV) vaccine has been available in Australia since 1994 and is recommended for high-risk groups including MSM. No outbreaks of hepatitis A in Australian MSM have been reported since 1996. In this study, we aimed to estimate HAV transmissibility in MSM populations in order to inform targets for vaccine coverage in such populations. We used mathematical models of HAV transmission in a MSM population to estimate the basic reproduction number (R0) and the probability of an HAV epidemic occurring as a function of the immune proportion. We estimated a plausible range forR0of 1·71–3·67 for HAV in MSM and that sustained epidemics cannot occur once the proportion immune to HAV is greater than ~70%. To our knowledge this is the first estimate ofR0and the critical population immunity threshold for HAV transmission in MSM. As HAV is no longer endemic in Australia or in most other developed countries, vaccination is the only means of maintaining population immunity >70%. Our findings provide impetus to promote HAV vaccination in high-risk groups such as MSM.
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THOMAS, EMMA G., HANNAH E. BARRINGTON, KAMALINI M. LOKUGE, and GEOFFRY N. MERCER. "MODELLING THE SPREAD OF TUBERCULOSIS, INCLUDING DRUG RESISTANCE AND HIV: A CASE STUDY IN PAPUA NEW GUINEA’S WESTERN PROVINCE." ANZIAM Journal 52, no. 1 (July 2010): 26–45. http://dx.doi.org/10.1017/s1446181111000587.
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AbstractHigh tuberculosis (TB) prevalence in Papua New Guinea (PNG) is a serious public health concern. The epidemic in this region is exacerbated by the presence of drug-resistant TB strains as well as HIV infection. This presents a public health threat not only locally but also to Australia due to the high potential for cross-border transmission between PNG’s Western Province and the Australian Torres Strait Islands. We present two mathematical models of TB in the Western Province: a simple model of the underlying TB dynamics, and a detailed model which accounts for the additional effects of HIV and drug resistance. The detailed model is used to make quantitative predictions about the impact of expanding the TB case detection rate under the Directly Observed Treatment, Short-course treatment regimen. This paper provides a framework for future investigation into the economic costs and public health benefits of potential TB interventions in this region, with the eventual aim of providing recommendations to guide policy makers in both PNG and Australia.
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Nogueira Reis, Pedro M., and Marion Gomes Augusto. "Determinants Of Firm Terminal Value: The Perspective Of North American And European Financial Analysts." International Business & Economics Research Journal (IBER) 13, no. 4 (June 30, 2014): 793. http://dx.doi.org/10.19030/iber.v13i4.8687.
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Company valuation models attempt to estimate the value of a company in two stages: (1) comprising of a period of explicit analysis and (2) based on unlimited production period of cash flows obtained through a mathematical approach of perpetuity, which is the terminal value. In general, these models, whether they belong to the Dividend Discount Model (DDM), the Discount Cash Flow (DCF), or RIM (Residual Income Models) group, discount one attribute (dividends, free cash flow, or results) to a given discount rate. This discount rate, obtained in most cases by the CAPM (Capital asset pricing model) or APT (Arbitrage pricing theory) allows including in the analysis the cost of invested capital based on the risk taking of the attributes. However, one cannot ignore that the second stage of valuation that is usually 53-80% of the company value (Berkman et al., 1998) and is loaded with uncertainties. In this context, particular attention is needed to estimate the value of this portion of the company, under penalty of the assessment producing a high level of error. Mindful of this concern, this study sought to collect the perception of European and North American financial analysts on the key features of the company that they believe contribute most to its value. For this feat, we used a survey with closed answers. From the analysis of 123 valid responses using factor analysis, the authors conclude that there is great importance attached (1) to the life expectancy of the company, (2) to liquidity and operating performance, (3) to innovation and ability to allocate resources to R&D, and (4) to management capacity and capital structure, in determining the value of a company or business in long term. These results contribute to our belief that we can formulate a model for valuating companies and businesses where the results to be obtained in the evaluations are as close as possible to those found in the stock market.
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Ellahi, Rahmat. "Special Issue on Symmetry and Fluid Mechanics." Symmetry 12, no. 2 (February 13, 2020): 281. http://dx.doi.org/10.3390/sym12020281.
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This Special Issue invited researchers to contribute their original research work and review articles on “Symmetry and Fluid Mechanics” that either advances the state-of-the-art mathematical methods through theoretical or experimental studies or extends the bounds of existing methodologies with new contributions related to the symmetry, asymmetry, and lie symmetries of differential equations proposed as mathematical models in fluid mechanics, thereby addressing current challenges. In response to the call for papers, a total of 42 papers were submitted for possible publication. After comprehensive peer review, only 25 papers qualified for acceptance for final publication. The rest of the papers could not be accommodated. The submissions may have been technically correct but were not considered appropriate for the scope of this Special Issue. The authors are from geographically distributed countries such as the USA, Australia, China, Saudi Arabia, Iran, Pakistan, Malaysia, Abu Dhabi, UAE, South Africa, and Vietnam. This reflects the great impact of the proposed topic and the effective organization of the guest editorial team of this Special Issue.
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NDII, MEKSIANIS Z., ROSLYN I. HICKSON, and GEOFFRY N. MERCER. "MODELLING THE INTRODUCTION OF WOLBACHIA INTO AEDES AEGYPTI MOSQUITOES TO REDUCE DENGUE TRANSMISSION." ANZIAM Journal 53, no. 3 (January 2012): 213–27. http://dx.doi.org/10.1017/s1446181112000132.
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AbstractInfecting Aedes aegypti mosquitoes with the bacteria Wolbachia has been proposed as an innovative new strategy to reduce the transmission of dengue fever. Field trials are currently being undertaken in Queensland, Australia. However, few mathematical models have been developed to consider the persistence of Wolbachia-infected mosquitoes in the wild. This paper develops a mathematical model to determine the persistence of Wolbachia-infected mosquitoes by considering the competition between Wolbachia-infected and non-Wolbachia mosquitoes. The model has four steady states that are biologically feasible: all mosquitoes dying out, only non-Wolbachia mosquitoes surviving, and two steady states where non-Wolbachia and Wolbachia-infected mosquitoes coexist. The stability of the steady states is determined with respect to the key parameters in the mosquito life cycle. A global sensitivity analysis of the model is also conducted. The results show that the persistence of Wolbachia-infected mosquitoes is dominated by the reproductive rate, death rate, maturation rate and maternal transmission. For the parameter values where Wolbachia persists, it dominates the population, and hence the introduction of Wolbachia has great potential to reduce dengue transmission.
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Om, Dorji, Chompunooch Thamanukornsri, kado, and Montip Tiensuwan. "Application of Box-Jenkins Models to the Tourist Inflow in Bhutan." Journal of Mathematical Sciences & Computational Mathematics 3, no. 1 (October 4, 2021): 13–25. http://dx.doi.org/10.15864/jmscm.3102.
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Bhutan has now increasingly become a popular destination for many international tourists. Tourism in Bhutan is considered as one of the largest foreign earning industries. The number of tourist inflow in the country is increasing year by year. Forecasting is very necessary for administration and tourist agent for creating awareness and planning for the future development. It can also predict the future trends as accurately as possible and helps in staying one step ahead of the competition. This study aims to apply mathematical model for forecasting monthly tourist inflow from Malaysia, Singapore, China, USA, England, France, Germany, Thailand, Australia and Japan to Bhutan. The Box-Jenkins model is used to identify the parameters of Autoregressive integrated moving average (ARIMA) model of monthly tourist visited data of above mentioned countries in the period 2011-2015 obtained from Tourism Council of Bhutan. An Akaike's Information Criterion, Schwartz's Bayesian Criterion and estimate variance of white noise are used throughout to test for the identification of best fit model. Further, the periodogram analysis was used to confirm the seasonal period of the model. The results showed ARIMA model for Thai, Chinese, Malaysian and Japanese, while seasonal ARIMA for American, Australian, British, French, Singaporean and German. Further, seasonal ARIMA model was obtained as the best fit model for the overall data. These models are illustrated and could possibly forecast the monthly tourist inflow of one year ahead with acceptable accuracy.
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Kvartenko, Oleksandr, and Igor Prysiazhniuk. "Modeling the process of biological deferrization of underground waters in contact loading of bioreactor." Problems of Water supply, Sewerage and Hydraulic, no. 41 (December 9, 2022): 19–30. http://dx.doi.org/10.32347/2524-0021.2022.41.19-30.
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The conducted analysis of modern biotechnologies in the field of groundwater treatment showed that one of the development trends is the direction of biological iron removal, which has not only a long history and fundamentality of research into the physiology, ultrastructure and life mechanisms of ferrobacteria, but also a wide implementation of the method at water treatment plants in Europе, Australia, Canada, USA, Japan. The introduction of modern technological equipment at such stations calls for the need to forecast their work using methods of mathematical modeling of processes with their subsequent computer implementation. The work provides a brief analysis of existing mathematical models, most of which are based on the kinetics of enzymatic reactions and are presented as modifications of the Michaelis-Menten and Monod equations.
Despite the large number of studies on this topic, until now there is no comprehensive model that would take into account all the processes that take place in the contact loading of bioreactors, in contrast to the physicochemical mechanisms in the filtering process, for which modern multicomponent mathematical models have been developed.
The aim of the work is to development of a mathematical model of the kinetics of the process of biological iron removal groundwater in bioreactors and verification of its computer implementation with the data of experimental studies. The mathematical model is represented by the Cauchy problem for a nonlinear system of differential equations in partial derivatives of the first order. The system of the Cauchy problem consists of five equations with five unknown functions, which describe the distribution the concentration of ferrum cations, bacteria and the matrix structures in two phases (movable and immobilized) both in space and time The inverse influence of the characteristics of the process, in particular, the concentration of matrix structures in the inter-pore space, as well as characteristics of the medium with the help of coefficients of mass exchange and porosity, were taken into account. The model makes it possible to predict changes in cleaning efficiency depending on the duration of the filter cycle, filtration speed, Fe2+ concentration, the content of iron bacteria and their matrix structures in the interpore space, and to determine the optimal time of operation of the bioreactor between washings
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Zhang, N., D. K. Liu, J. M. Jeyakumaran, and L. Villanueva. "Modelling of dynamic characteristics of an automatic transmission during shift changes." Proceedings of the Institution of Mechanical Engineers, Part I: Journal of Systems and Control Engineering 216, no. 4 (June 1, 2002): 331–41. http://dx.doi.org/10.1177/095965180221600403.
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This paper describes modelling of the transient dynamics of an automatic transmission during gear changes. A brief introduction to the automatic transmission system and the dynamic characteristics of the transmission components during the gear changes are presented. Then, detailed mathematical models of a four-speed automatic transmission manufactured by BTR Automotive, Australia, are developed. A mode description method is used to describe the transient shifting process and a modular structure of the transmission system, which consists of a torque converter module, geartrain module, hydraulic system module and modules of clutches and bands, is presented. As an application, the developed simulation system is applied to investigate the transient performance of the automatic transmission during the 1–2 shift process. The output torque profiles predicted by the model simulation correlate very well with the experimental data measured from vehicle tests.
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Al Hinai, Adnan, Reza Rezaee, Ali Saeedi, and Roland Lenormand. "Permeability prediction from mercury injection capillary pressure: an example from the Perth Basin, Western Australia." APPEA Journal 53, no. 1 (2013): 31. http://dx.doi.org/10.1071/aj12003.
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For shale gas reservoirs, permeability is one of the most important and difficult parameters to determine. Typical shale matrix permeabilities are in the range of 10 microdarcy–100 nanodarcy, and are heavily dependent on the presence of natural fractures for gas transmissibility. Permeability is a parameter used to measure the ability of a rock to convey fluid. It is directly related to porosity and depends on the pore geometry features, such as tortuosity, pore shape and pore connectivity. Consequently, rocks with similar porosity can exhibit different permeability. Generally, permeability is measured in laboratories using core plugs. In some cases, however, it is difficult to obtain suitable core plugs. In these instances, other approaches can be used to predict permeability, which are chiefly based on mathematical and theoretical models. The approach followed in this peer-reviewed paper is to correlate permeability with capillary pressure data from mercury injection measurements. The theoretical and empirical equations, introduced in the literature for various conventional and unconventional reservoir rocks, have been used to predict permeability. Estimated gas shale permeabilities are then compared with results from transient and steady state methods on small pieces of rocks embedded in a resin disk. The study also attempts to establish a suitable equation that is applicable to gas shale formations and to investigating the relationship between permeability and porosity.
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Lydeamore, M. J., P. T. Campbell, W. Cuningham, R. M. Andrews, T. Kearns, D. Clucas, R. Gundjirryirr Dhurrkay, et al. "Calculation of the age of the first infection for skin sores and scabies in five remote communities in northern Australia." Epidemiology and Infection 146, no. 9 (May 8, 2018): 1194–201. http://dx.doi.org/10.1017/s0950268818001061.
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AbstractPrevalence of skin sores and scabies in remote Australian Aboriginal communities remains unacceptably high, with Group AStreptococcus(GAS) the dominant pathogen. We aim to better understand the drivers of GAS transmission using mathematical models. To estimate the force of infection, we quantified the age of first skin sores and scabies infection by pooling historical data from three studies conducted across five remote Aboriginal communities for children born between 2001 and 2005. We estimated the age of the first infection using the Kaplan–Meier estimator; parametric exponential mixture model; and Cox proportional hazards. For skin sores, the mean age of the first infection was approximately 10 months and the median was 7 months, with some heterogeneity in median observed by the community. For scabies, the mean age of the first infection was approximately 9 months and the median was 8 months, with significant heterogeneity by the community and an enhanced risk for children born between October and December. The young age of the first infection with skin sores and scabies reflects the high disease burden in these communities.
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GLASS, K., and N. G. BECKER. "Evaluation of measures to reduce international spread of SARS." Epidemiology and Infection 134, no. 5 (February 14, 2006): 1092–101. http://dx.doi.org/10.1017/s0950268806005863.
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Mathematical models are used to quantify the effect of border control measures in reducing the international spread of SARS. Border screening is shown to play a relatively minor role in reducing disease spread. Assuming detection rates similar to those reported for arrival screening in Australia, screening can detect up to 10% (95% CI 3–23) of infected travellers, and reduce the probability of a large outbreak by up to 7% (95% CI 2–17). Rapid reductions in the time to diagnosis and effective facilities for the isolation of cases are essential to ensure that there will not be a large outbreak, and each week of delay in responding to imported infection approximately doubles the total number of cases. While the control response is being developed in a currently uninfected region, border screening can provide up to one week's additional time in which to improve methods for early isolation of cases.
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Lambert, M. F., J. P. Whiting, and A. V. Metcalfe. "A non-parametric hidden Markov model for climate state identification." Hydrology and Earth System Sciences 7, no. 5 (October 31, 2003): 652–67. http://dx.doi.org/10.5194/hess-7-652-2003.
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Abstract. Hidden Markov models (HMMs) can allow for the varying wet and dry cycles in the climate without the need to simulate supplementary climate variables. The fitting of a parametric HMM relies upon assumptions for the state conditional distributions. It is shown that inappropriate assumptions about state conditional distributions can lead to biased estimates of state transition probabilities. An alternative non-parametric model with a hidden state structure that overcomes this problem is described. It is shown that a two-state non-parametric model produces accurate estimates of both transition probabilities and the state conditional distributions. The non-parametric model can be used directly or as a technique for identifying appropriate state conditional distributions to apply when fitting a parametric HMM. The non-parametric model is fitted to data from ten rainfall stations and four streamflow gauging stations at varying distances inland from the Pacific coast of Australia. Evidence for hydrological persistence, though not mathematical persistence, was identified in both rainfall and streamflow records, with the latter showing hidden states with longer sojourn times. Persistence appears to increase with distance from the coast. Keywords: Hidden Markov models, non-parametric, two-state model, climate states, persistence, probability distributions
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Baird, Mark E., Karen A. Wild-Allen, John Parslow, Mathieu Mongin, Barbara Robson, Jennifer Skerratt, Farhan Rizwi, et al. "CSIRO Environmental Modelling Suite (EMS): scientific description of the optical and biogeochemical models (vB3p0)." Geoscientific Model Development 13, no. 9 (September 25, 2020): 4503–53. http://dx.doi.org/10.5194/gmd-13-4503-2020.
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Abstract. Since the mid-1990s, Australia's Commonwealth Science Industry and Research Organisation (CSIRO) has been developing a biogeochemical (BGC) model for coupling with a hydrodynamic and sediment model for application in estuaries, coastal waters and shelf seas. The suite of coupled models is referred to as the CSIRO Environmental Modelling Suite (EMS) and has been applied at tens of locations around the Australian continent. At a mature point in the BGC model's development, this paper presents a full mathematical description, as well as links to the freely available code and user guide. The mathematical description is structured into processes so that the details of new parameterisations can be easily identified, along with their derivation. In EMS, the underwater light field is simulated by a spectrally resolved optical model that calculates vertical light attenuation from the scattering and absorption of 20+ optically active constituents. The BGC model itself cycles carbon, nitrogen, phosphorous and oxygen through multiple phytoplankton, zooplankton, detritus and dissolved organic and inorganic forms in multiple water column and sediment layers. The water column is dynamically coupled to the sediment to resolve deposition, resuspension and benthic–pelagic biogeochemical fluxes. With a focus on shallow waters, the model also includes detailed representations of benthic plants such as seagrass, macroalgae and coral polyps. A second focus has been on, where possible, the use of geometric derivations of physical limits to constrain ecological rates. This geometric approach generally requires population-based rates to be derived from initially considering the size and shape of individuals. For example, zooplankton grazing considers encounter rates of one predator on a prey field based on summing relative motion of the predator with the prey individuals and the search area; chlorophyll synthesis includes a geometrically derived self-shading term; and the bottom coverage of benthic plants is calculated from their biomass using an exponential form derived from geometric arguments. This geometric approach has led to a more algebraically complicated set of equations when compared to empirical biogeochemical model formulations based on populations. But while being algebraically complicated, the model has fewer unconstrained parameters and is therefore simpler to move between applications than it would otherwise be. The version of EMS described here is implemented in the eReefs project that delivers a near-real-time coupled hydrodynamic, sediment and biogeochemical simulation of the Great Barrier Reef, northeast Australia, and its formulation provides an example of the application of geometric reasoning in the formulation of aquatic ecological processes.
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McCallum, H. I., and G. R. Singleton. "Models to assess the potential of Capillaria hepatica to control population outbreaks of house mice." Parasitology 98, no. 3 (June 1989): 425–37. http://dx.doi.org/10.1017/s0031182000061515.
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SUMMARYPopulation outbreaks of house mice (Mus domesticus) occur periodically in the wheatlands of southeastern Australia. This paper uses mathematical models to assist in the evaluation of the potential of a nematode, Capillaria hepatica, as a biological control agent to reduce the severity of these ‘plagues’. C. hepatica is unique amongst helminths of mammals in that its eggs are released only upon the death of an infected host. The major goal of the modelling in this paper is to determine the impact of this feature on the population dynamics of the host-parasite interaction. Simple differential equation models are used to examine the general properties of the system and determine which population parameters are most crucial to the outcome of the interaction. These models are supplemented by age-structured models which investigate the initial behaviour of the system after introduction of the parasite. The necessity of host death for transmission is a strongly destabilizing factor, suggesting that C. hepatica cannot regulate most populations stably in the absence of strong resource limitation, although it has the potential to depress mouse populations below infection-free levels. Although C. hepatica influences mouse fecundity at lower burdens than it affects mortality, the age-structured models show that parasite-induced host death cannot be neglected. Because transmission requires host death, the parasite life-cycle operates on a time-scale similar to that of the hosts, and introduction of the parasite as early as possible in the development period of an outbreak will therefore be necessary to achieve substantial reductions in plague intensity.
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Vino, Thiripura, Gurmeet R. Singh, Belinda Davison, Patricia T. Campbell, Michael J. Lydeamore, Andrew Robinson, Jodie McVernon, Steven Y. C. Tong, and Nicholas Geard. "Indigenous Australian household structure: a simple data collection tool and implications for close contact transmission of communicable diseases." PeerJ 5 (October 26, 2017): e3958. http://dx.doi.org/10.7717/peerj.3958.
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Households are an important location for the transmission of communicable diseases. Social contact between household members is typically more frequent, of greater intensity, and is more likely to involve people of different age groups than contact occurring in the general community. Understanding household structure in different populations is therefore fundamental to explaining patterns of disease transmission in these populations. Indigenous populations in Australia tend to live in larger households than non-Indigenous populations, but limited data are available on the structure of these households, and how they differ between remote and urban communities. We have developed a novel approach to the collection of household structure data, suitable for use in a variety of contexts, which provides a detailed view of age, gender, and room occupancy patterns in remote and urban Australian Indigenous households. Here we report analysis of data collected using this tool, which quantifies the extent of crowding in Indigenous households, particularly in remote areas. We use these data to generate matrices of age-specific contact rates, as used by mathematical models of infectious disease transmission. To demonstrate the impact of household structure, we use a mathematical model to simulate an influenza-like illness in different populations. Our simulations suggest that outbreaks in remote populations are likely to spread more rapidly and to a greater extent than outbreaks in non-Indigenous populations.
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Xu, Xiaodong, and Huifeng Xu. "Investment-internal capital sensitivity, investment-cash flow sensitivity and dividend payment." China Finance Review International 9, no. 2 (May 20, 2019): 183–207. http://dx.doi.org/10.1108/cfri-06-2017-0103.
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Purpose On the basis of principal-agent and financing constraints theories, the purpose of this paper is to construct a unified research framework via mathematical models and to provide a logical and consistent explanation of the contradictory discovery of the relationship between dividend payment and I-CFO in the previous literature. Design/methodology/approach Establishing the economic mathematical models, this paper uses the comparative static analysis to figure out the equilibrium results, to further testify the conclusions, the authors initiate the empirical tests to make the discussion more realistic. Findings The authors observe that overinvestment caused by agency problems is the primary reason for I-C sensitivity when the investment expenditure is less than the internal capital; dividend payout suppresses the overinvestment caused by the agency problem, thus alleviating the investment’s dependence on the internal capital. However, underinvestment caused by the financing constraints is the primary cause of I-C sensitivity when the investment expenditure is greater than the internal capital. The payment of cash dividends increases the investment shortage caused by the financing constraints, thus increasing the sensitivity. Further, the authors explore the impact of dividend payments on I-CFO sensitivity. They argue that dividend payment is not an appropriate measure of financing constraints. Both I-CFO sensitivity and I-C sensitivity are functions of agency cost and information cost. Research limitations/implications This study provides a logical and consistent explanation of the contradictory discovery of the relationship between dividend payment and I-CFO in the previous literature and provides a clear framework and reference for future studies on the impact of financial constraints, agency cost on the investment’s dependence on the internal capital. Practical implications The theoretical model of this paper supports this differentiated mandatory dividend policy and provides reference and evidence for China's financing policies and dividend distribution policies. Originality/value This study theoretically and empirically analyzes and verifies the roles of agency cost and financial constraints on the determinants of I-C sensitivity for the first time. First, different from earlier literature, this paper puts forward I-C sensitivity as a new measure of investment’s dependence on internal capital, making the measurement more accurate. In the case of a firm with positive liquidity reserves, using the I-CFO sensitivity as a measure of external financing constraints could overestimate the firm’s financial constraints. Second, by constructing an economic static analysis framework, this study analyzes how I-C and I-CFO sensitivities change with the agency cost, the financing constraints and the dividend payment ratio. The research provides a basic framework and explanation on the contradictions of the earlier literature. The results are supposed to serve as a foundation for estimations of investment’s dependence on internal capital and should be embedded in general empirical tests in future research.
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Parsons, Scott A., and Robert A. Congdon. "Plant litter decomposition and nutrient cycling in north Queensland tropical rain-forest communities of differing successional status." Journal of Tropical Ecology 24, no. 3 (May 2008): 317–27. http://dx.doi.org/10.1017/s0266467408004963.
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Abstract:Soil processes are essential in enabling forest regeneration in disturbed landscapes. Little is known about whether litterfall from dominating pioneer species in secondary rain forest is functionally equivalent to that of mixed rain-forest litter in terms of contribution to soil processes. This study used the litterbag technique to quantify the decomposition and nutrient dynamics of leaf litter characteristic of three wet tropical forest communities in the Paluma Range National Park, Queensland, Australia over 511 d. These were: undisturbed primary rain forest (mixed rain-forest species), selectively logged secondary rain forest (pioneer Alphitonia petriei) and tall open eucalypt forest (Eucalyptus grandis). Mass loss, total N, total P, K, Ca and Mg dynamics of the decaying leaves were determined, and different mathematical models were used to explain the mass loss data. Rainfall and temperature data were also collected from each site. The leaves of A. petriei and E. grandis both decomposed significantly slower in situ than the mixed rain-forest species (39%, 38% and 29% ash-free dry mass remaining respectively). Nitrogen and phosphorus were immobilized, with 182% N and 134% P remaining in E. grandis, 127% N and 132% P remaining in A. petriei and 168% N and 121% P remaining in the mixed rain-forest species. The initial lignin:P ratio and initial lignin:N ratio exerted significant controls on decomposition rates. The exceptionally slow decomposition of the pioneer species is likely to limit soil processes at disturbed tropical rain-forest sites in Australia.
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Hui, Ben B., David P. Wilson, James S. Ward, Rebecca J. Guy, John M. Kaldor, Matthew G. Law, Jane S. Hocking, and David G. Regan. "The potential impact of new generation molecular point-of-care tests on gonorrhoea and chlamydia in a setting of high endemic prevalence." Sexual Health 10, no. 4 (2013): 348. http://dx.doi.org/10.1071/sh13026.
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Background Despite the availability of testing and treatment, bacterial sexually transmissible infections (STIs) continue to occur at endemic levels in many remote Indigenous communities in Australia. New generation molecular point-of-care (POC) tests have high sensitivity, comparable with conventional diagnostic tests, and have the potential to increase the impact of STI screening. Methods: We developed mathematical models of gonorrhoea (Neisseria gonorrhoeae) and chlamydia (Chlamydia trachomatis) transmission in remote Indigenous communities in Australia to evaluate screening and treatment strategies that utilise POC tests. Results: The introduction of POC testing with 95% sensitivity could reduce the prevalence of gonorrhoea and chlamydia from 7.1% and 11.9% to 5.7% and 8.9%, respectively, under baseline screening coverage of 44% per year. If screening coverage is increased to 60% per year, prevalence is predicted to be reduced to 3.6% and 6.7%, respectively, under conventional testing, and further reduced to 1.8% and 3.1% with the introduction of POC testing. Increasing screening coverage to 80% per year will result in a reduction in the prevalence of gonorrhoea and chlamydia to 0.6% and 1.5%, respectively, and the virtual elimination of both STIs if POC testing is introduced. Conclusions: Modelling suggests that molecular POC tests of high sensitivity have great promise as a public health strategy for controlling chlamydia and gonorrhoea. However, evaluation of the cost-effectiveness of POC testing needs to be made before widespread implementation of this technology can be considered.
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Sarker, Chandrama, Luis Mejias, Frederic Maire, and Alan Woodley. "Flood Mapping with Convolutional Neural Networks Using Spatio-Contextual Pixel Information." Remote Sensing 11, no. 19 (October 8, 2019): 2331. http://dx.doi.org/10.3390/rs11192331.
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Remote sensing technology in recent years has been regarded the most important source to provide substantial information for delineating the flooding extent to the disaster management authority. There have been numerous studies proposing mathematical or statistical classification models for flood mapping. However, conventional pixel-wise classifications methods rely on the exact match of the spectral signature to label the target pixel. In this study, we propose a fully convolutional neural networks (F-CNNs) classification model to map the flooding extent from Landsat satellite images. We utilised the spatial information from the neighbouring area of target pixel in classification. A total of 64 different models were generated and trained with a variable neighbourhood size of training samples and number of learnable filters. The training results revealed that the model trained with 3 × 3 neighbourhood sized training samples and with 32 convolutional filters achieved the best performance out of the experiments. A new set of different Landsat images covering flooded areas across Australia were used to evaluate the classification performance of the model. A comparison of our proposed classification model to the conventional support vector machines (SVM) classification model shows that the F-CNNs model was able to detect flooded areas more efficiently than the SVM classification model. For example, the F-CNNs model achieved a maximum precision rate (true positives) of 76.7% compared to 45.27% for SVM classification.
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Yuan, Gauthier, Hungerford, Ouwerkerk, Fletcher, and Laycock. "Modelling the Controlled Release of Toxins in a Rumen Environment." Proceedings 36, no. 1 (February 12, 2020): 89. http://dx.doi.org/10.3390/proceedings2019036089.
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Pimelea poisoning in grazing cattle, also known as St George or Marree Disease, has been a long-time pestilence for the pastoral industry throughout arid regions of inland Australia. The causative species Pimelea (Thymelaeaceae), native to Queensland, New South Wales and South Australia, have been confirmed, with the secondary metabolite simplexin, a daphnane orthoester, being extracted and identified as the principal toxin. Despite the lack of effective prevention or treatment for Pimelea poisoning, naïve calves have previously been demonstrated to develop detoxification capability following prolonged low-dose simplexin intake. A variety of composites are being fabricated by encapsulating Pimelea plant material or a crude extract in biodegradable and biocompatible polyesters, aiming to develop a sustained toxin release mechanism. Studies on screening potential rumen microflora able to decompose simplexin during rumen-fluid fermentation are being conducted simultaneously. In this project, a quantification method for simplexin within these biocomposites was developed and validated utilising solid-phase extraction combined with UHPLC-Q-Orbitrap MS/MS. Reliable simplexin measurement in matrices will allow investigations into the material composition, geometry and rumen microorganism’s effects on the controlled release kinetics of simplexin in vitro. The degradation patterns of toxin delivery systems when exposed to simulated rumen environments will also be thoroughly assessed on both microscopic and chemical scales. Mathematical models of the underlying mass transport mechanisms will ultimately be established through approaches ranging from simple empirical correlations to stochastic simulations, which hold the potential to facilitate future design, optimisation, and prediction of other intra-ruminal devices based on biodegradable polymers.
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Austin, Oshin Ola. "Advanced Control And Development of Hydro and Diesel Generator Hybrid Power System Models for Renewable Energy Microgrids." Journal La Multiapp 2, no. 3 (August 11, 2021): 16–32. http://dx.doi.org/10.37899/journallamultiapp.v2i3.383.
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The Nigerian power problem resulted to incessant and erratic supply of electricity and this has destroyed many industrial processes in the country. It has reduced productivity and has increased unemployment rate in the country to over 50million (this figure is over 70% of Nigerian youths). This has led many of the youths in the country to crime. It has led to the deaths of many innocent people in the country. As of 2016, the electricity energy consumption in the world from the world fact book revealed that the average power per capita (watts per person) in the United States is 1,377 Watts. In Canada, it is 1704 Watts per person and in South Africa; it is 445 Watts per person and in Australia, average power per capita (watts per person) is as high as 1,112 Watts. Whereas, the average electricity consumed in watts per person in Nigeria is just 14 Watts. Unfortunately, this has put the country in a rank of 189 out of 219 countries estimated. In this research work, a Hybrid Electric Power System (HEPS) which comprises Hydro Electric Power Plant (HEPP) and Diesel Generator (DG) was modelled and a control algorithm was established to improve the performance of the system. Hybrid power system mathematical and Simulink models were developed. The output power of the developed Simulink model was be optimized using optimum power point optimization techniques and control algorithms. Simulink models of the two components of the Hybrid Electric Power System were produced using MATLAB/Simulink software. The develop Simulink models was interconnected and final model was developed. The results obtained revealed that the problems associated with conventional methods of power generation was overcomed by the development of this renewable and non-renewable energy resources Hybrid Electric Power System (HEPS) models.
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da Silva, Graciane Fabiela, Edgar Teixeira de Souza Júnior, Rafael Nolibos Almeida, Ana Luisa Butelli Fianco, Alexandre Timm do Espirito Santo, Aline Machado Lucas, Rubem Mário Figueiró Vargas, and Eduardo Cassel. "The Response Surface Optimization of Supercritical CO2 Modified with Ethanol Extraction of p-Anisic Acid from Acacia mearnsii Flowers and Mathematical Modeling of the Mass Transfer." Molecules 27, no. 3 (January 31, 2022): 970. http://dx.doi.org/10.3390/molecules27030970.
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A widely disseminated native species from Australia, Acacia mearnsii, which is mainly cultivated in Brazil and South Africa, represents a rich source of natural tannins used in the tanning process. Many flowers of the Acacia species are used as sources of compounds of interest for the cosmetic industry, such as phenolic compounds. In this study, supercritical fluid extraction was used to obtain non-volatile compounds from A. mearnsii flowers for the first time. The extract showed antimicrobial activity and the presence of p-anisic acid, a substance with industrial and pharmaceutical applications. The fractionation of the extract was performed using a chromatographic column and the fraction containing p-anisic acid presented better minimum inhibitory concentration (MIC) results than the crude extract. Thus, the extraction process was optimized to maximize the p-anisic acid extraction. The response surface methodology and the Box–Behnken design was used to evaluate the pressure, temperature, the cosolvent, and the influence of the particle size on the extraction process. After the optimization process, the p-anisic acid yield was 2.51% w/w and the extraction curve was plotted as a function of time. The simulation of the extraction process was performed using the three models available in the literature.
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Bertone, E., K. O'Halloran, M. Bartkow, and K. Mann. "Autonomous intake selection optimisation model for a dual source drinking water treatment plant." Water Supply 18, no. 1 (June 16, 2017): 279–87. http://dx.doi.org/10.2166/ws.2017.111.
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Abstract The Mudgeeraba drinking water treatment plant, in Southeast Queensland, Australia, can withdraw raw water from two different reservoirs: the smaller Little Nerang dam (LND) by gravity, and the larger Advancetown Lake, through the use of pumps. Selecting the optimal intake is based on water quality and operators' experience; however, there is potential to optimise this process. In this study, a comprehensive hybrid (data-driven, chemical, and mathematical) intake optimisation model was developed, which firstly predicts the chemicals dosages, and then the total (chemicals and pumping) costs based on the water quality at different depths of the two reservoirs, thus identifying the cheapest option. A second data-driven, probabilistic model then forecasts the volume of the smaller LND 6 weeks ahead in order to minimise the depletion and spill risks. This is important in case the first model identifies this reservoir as the optimal intake solution, but this could lead in the long term to depletion and full reliance on the electricity-dependent Advancetown Lake. Both models were validated and proved to be accurate, and with the potential for substantial monetary savings for the water utility.
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Friend, Adrian J., Godwin A. Ayoko, Daniel Jager, Megan Wust, E. Rohan Jayaratne, Milan Jamriska, and Lidia Morawska. "Sources of ultrafine particles and chemical species along a traffic corridor: comparison of the results from two receptor models." Environmental Chemistry 10, no. 1 (2013): 54. http://dx.doi.org/10.1071/en12149.
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Environmental context Identifying the sources responsible for air pollution is crucial for reducing the effect of the pollutants on human health. The sources of the pollutants were found here by applying two mathematical models to data consisting of particle size distribution and chemical composition data. The identified sources could be used as the basis for controlling or reducing emissions of air pollution into the atmosphere. Abstract Particulate matter is common in our environment and has been linked to human health problems particularly in the ultrafine size range. In this investigation, the sources of particles measured at two sites in Brisbane, Australia, were identified by analysing particle number size distribution data, chemical species concentrations and meteorological data with two source apportionment models. The source apportionment results obtained by positive matrix factorisation (PMF) and principal component analysis–absolute principal component scores (PCA–APCS) were compared with information from the gaseous chemical composition analysis. Although PCA–APCS resolved more sources, the results of the PMF analysis appear to be more reliable. Six common sources were identified by both methods and these include: traffic 1, traffic 2, local traffic, biomass burning and two unassigned factors. Thus motor vehicle related activities had the greatest effect on the data with the average contribution from nearly all sources to the measured concentrations being higher during peak traffic hours and weekdays. Further analyses incorporated the meteorological measurements into the PMF results to determine the direction of the sources relative to the measurement sites, and this indicated that traffic on the nearby road and intersection was responsible for most of the factors. The described methodology that utilised a combination of three types of data related to particulate matter to determine the sources and combination of two receptor models could assist future development of particle emission control and reduction strategies.
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Morgan, Damian, and Joan Ozanne-Smith. "Drowning Risk Analysis Comparing Surf Bather Subgroups." Applied Sciences 11, no. 24 (December 17, 2021): 12047. http://dx.doi.org/10.3390/app112412047.
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The study assessed the utility of risk analysis for advancing knowledge on drowning risk factors. The setting was unintentional drowning of surf bathers in Australia. Bathers reported earlier exposure to selected risk factors (swimming ability, wave height associated with rip currents and surf bathing experience) and were observed for water exposure (in minutes). These data were then assembled in mathematical models. The analysis forecast relative drowning risk pertaining to risk markers representing selected surf bather subgroups (gender, age and water activity). Contextualized through previous study findings, comparison of results with a gold standard obtained from mortality data generated new surf bather drowning hypotheses suitable for future testing by rigorous analytical epidemiologic designs. The hypotheses were: (1) The male to female comparative surf bather drowning rate is explained primarily by differences in crude water exposure; (2) the association of cardio-vascular medical conditions with surf bather drowning is stronger for older surf bathers compared to younger surf bathers; and (3) other risk contributors to surf bather drowning are: Poorly calibrated perception of bathing ability (overconfidence) and use of alcohol. Nonetheless, drowning rates appear generally consistent with time exposure to water. The study findings may also support drowning prevention strategies targeting risk marker subgroups.
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Elghaish, Faris, M. Reza Hosseini, Saeed Talebi, Sepehr Abrishami, Igor Martek, and Michail Kagioglou. "Factors Driving Success of Cost Management Practices in Integrated Project Delivery (IPD)." Sustainability 12, no. 22 (November 16, 2020): 9539. http://dx.doi.org/10.3390/su12229539.
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Integrated project delivery (IPD) is a mode of project procurement recognised as facilitating superior project performance. However, this success is contingent on effective cost management practices that share cost data with all project stakeholders in an accurate, timely and transparent manner. Despite an extensive literature on aspects of cost management, none identifies the essential ingredients required of an effective cost management system, sufficiently robust to support successful IPD projects. Candidate cost management augmenting practices are drawn from the literature, and presented for scrutiny in questionnaire form, to fifty IPD experienced experts, based in the USA, UK and Australia. Findings reveal activity-based costing (ABC) to be effective at identifying overhead costs and creating accounting transparency. Similarly, earned value management (EVM), in combination with ABC, is effective at developing mathematical models for equitable risk-reward distribution. Moreover, web-based management systems, as supported by Building Information Modelling (BIM), are effective at generating trust and collaboration on which IPD success depends. A questionnaire survey using purposive sampling was conducted to assess the factors driving success of implementing IPD regarding cost management process. The contribution to knowledge made by this paper is in identifying requisite support mechanisms essential to elevate traditional cost management practices to the higher standard needed to ensure IPD delivery success.
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Evdokimov, Aleksey S. "Administrative and legal aspects of the development of a risk-oriented approach in Russia based on foreign practice." Gosudarstvo i pravo, no. 10 (2022): 116. http://dx.doi.org/10.31857/s102694520022612-4.
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The article discusses the current administrative and legal aspects of certain areas of reform of control and supervisory activities in the Russian Federation regarding the introduction of a risk-based approach, the process of its implementation and automation of this activity in comparison with foreign countries, including the countries of the British Commonwealth, the USA, Australia, etc. In the process of research, general scientific and particular scientific methods of cognition were applied: analytical, logical, mathematical, structural-functional, comparative-legal. The main contribution made by the authors in this article is the conclusion that it is necessary to develop legislation in the field of improving administrative and legal relations in the field of the state control system, supervision in general, and a separate direction for the modernization of this activity - a risk-based approach to the planning of ongoing inspections, in particular. The authors have developed a methodology for determining risk categories, and proposed mechanisms for its implementation in the Russian control and supervision doctrine as a basic organizational and legal principle that contributes to the qualitative development of a risk-based approach, the use of dynamic risk assessment models, and the transition to smart state regulation of the sphere of control and supervision.
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Kwon, Jisoo A., Georgina M. Chambers, Fabio Luciani, Lei Zhang, Shamin Kinathil, Dennis Kim, Hla-Hla Thein, et al. "Hepatitis C treatment strategies in prisons: A cost-effectiveness analysis." PLOS ONE 16, no. 2 (February 11, 2021): e0245896. http://dx.doi.org/10.1371/journal.pone.0245896.
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In Australian prisons approximately 20% of inmates are chronically infected with hepatitis C virus (HCV), providing an important population for targeted treatment and prevention. A dynamic mathematical model of HCV transmission was used to assess the impact of increasing direct-acting antiviral (DAA) treatment uptake on HCV incidence and prevalence in the prisons in New South Wales, Australia, and to assess the cost-effectiveness of alternate treatment strategies. We developed four separate models reflecting different average prison lengths of stay (LOS) of 2, 6, 24, and 36 months. Each model considered four DAA treatment coverage scenarios of 10% (status-quo), 25%, 50%, and 90% over 2016–2045. For each model and scenario, we estimated the lifetime burden of disease, costs and changes in quality-adjusted life years (QALYs) in prison and in the community during 2016–2075. Costs and QALYs were discounted 3.5% annually and adjusted to 2015 Australian dollars. Compared to treating 10% of infected prisoners, increasing DAA coverage to 25%, 50%, and 90% reduced HCV incidence in prisons by 9–33% (2-months LOS), 26–65% (6-months LOS), 37–70% (24-months LOS), and 35–65% (36-months LOS). DAA treatment was highly cost-effective among all LOS models at conservative willingness-to-pay thresholds. DAA therapy became increasingly cost-effective with increasing coverage. Compared to 10% treatment coverage, the incremental cost per QALY ranged from $497-$569 (2-months LOS), -$280–$323 (6-months LOS), -$432–$426 (24-months LOS), and -$245–$477 (36-months LOS). Treating more than 25% of HCV-infected prisoners with DAA therapy is highly cost-effective. This study shows that treating HCV-infected prisoners is highly cost-effective and should be a government priority for the global HCV elimination effort.
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Brennen, C. E., G. Keady, and J. Imberger. "A note on algal population dynamics." IMA Journal of Applied Mathematics 83, no. 4 (July 25, 2018): 783–96. http://dx.doi.org/10.1093/imamat/hxy010.
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Abstract This is a contribution to the special issue honoring the late John R. Blake of the University of Birmingham. All three authors had the pleasure of extensive technical interactions with John Blake during his career in the UK, USA and Australia and benefited both professionally and personally from his friendship. John’s work in developing fundamental mathematical solutions for Stokes’ flows and his application of those mathematical tools to analyses of microorganism locomotion led to special new insights into the world of small-scale swimming. This special issue devoted to John’s memory seems an appropriate occasion to present another fluid mechanical challenge associated with microorganisms, namely the dynamics of algal blooms. Though it is a special reduced-order model that is of limited practical value, John would have particularly enjoyed the analytical solution to the dynamics of algae that was presented by Rutherford Aris (1997, Reflections on Keats’ equation. Chem. Eng. Sci., 52, 2447–2455) in a somewhat eccentric paper. We revisit that solution in this paper and present an extension to Aris’ solution that includes sedimentation of the algae. We think that John would have enjoyed this solution and would, in all likelihood, have been able to expand upon it to include other features such as microorganism buoyancy variations (see, e.g. Kromkamp & Walsby 1990; Belov & Giles, 1997, Dynamical model of buoyant cyanobacteria. Hydrobiologia, 349, 87–97; Brookes & Ganf, 2001, Variations in the buoyancy response of Microcystis aeruginosa to nitrogen, phosphorus and light. J. Plankton Res., 23, 1399–1411), the death of algae (see, e.g. Serizawa et al., 2008a, Computer simulations of seasonal outbreak and diurnal vertical migration of cyanobacteria. Limnology, 9, 185–194; Reynolds, 1984, The Ecology of Freshwater Phytoplankton. Cambridge University Press), the swimming of algae (see, e.g. Pedley, 2016, Spherical squirmers: models for swimming micro-organisms. IMA J. Appl. Math., 81, 488–521) and other relevant hydrodynamic matters.
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Rujikiatkamjorn, Cholachat, and Buddhima Indraratna. "Analytical solution for radial consolidation considering soil structure characteristics." Canadian Geotechnical Journal 52, no. 7 (July 2015): 947–60. http://dx.doi.org/10.1139/cgj-2014-0277.
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A system of surcharge load combined with vertical drains to speed up consolidation of soft soil by reducing the drainage path is one of the most efficient and economical ground improvement techniques. In the field, conventional theories including smear zone have been commonly employed to predict the radial consolidation behaviour induced by vertical drains in soft clay. One of the key parameters in conventional analysis is the use of mean coefficient of volume compressibility and soil permeability, which are often assumed to be constant. The effect of drain installation on the soil compressibility of the in situ clay structure is often ignored. Laboratory testing has shown that the soil compressibility and permeability can vary nonlinearly over a considerable range of applied surcharge pressure, and both these properties can be affected during the drain installation. This study presents a mathematical model of radial consolidation via vertical drains incorporating the variations of soil compressibility and permeability as well as highlighting the effects of drain installation on those parameters. The main differences between the proposed and conventional models are elucidated, in terms of stress history and preloading (surcharge) pressure. The effects of preconsolidation pressure and the magnitude of applied preloading are examined through the dissipation of average excess pore pressure and associated settlement. Supported by experimental observations, the proposed theory is validated with field data of a selected case study in the town of Ballina, New South Wales, Australia.
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Iwanowicz, Damian. "Assessment of selected methods of estimating the maximum back-of-queue size on a signal-controlled intersection approach." Journal of Civil Engineering and Transport 4, no. 2 (December 31, 2022): 49–63. http://dx.doi.org/10.24136/tren.2022.008.
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The article presents the characteristics and evaluation of the accuracy of estimating the maximum length of the queue of vehicles at signalized intersections by commonly used methods in the world. The analyzes were based on the latest editions of the guidelines in the United States, Canada, Australia, Germany and Poland. In order to carry out accuracy analyzes, traffic tests were carried out at 5 intersection inlets in three different cities in Poland (Bydgoszcz, Torun, Warsaw), covering all phases of vehicle queue formation during individual periods of the signaling cycle (effective red and green signal). In total, the analysis had the results of tests from 81 hours of observation ~23,000 behaviors of vehicle drivers. Based on the analyzes it was found in particular: (1) slight differences in the construction of mathematical models of the considered calculation methods, with the exception of the US HCM model from 2016; (2) small errors in estimating the maximum queue length in unsaturated vehicle flow states (~3-5 vehicles/cycle and ~2-6 vehicles/15 minutes interval); (3) quite large errors in estimating the maximum queue length in saturated and oversaturated vehicle flow states (~11-16 vehicles/cycle and ~15-18 vehicles/15 minutes interval); (4) the main impact on estimation errors in oversaturation traffic states is not taking into account or incorrect determination of the 'so-called' initial queue length of the period preceding the analyzed period.
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Calma, Angelito. "The long and winding road." International Journal of Educational Management 31, no. 4 (May 8, 2017): 418–29. http://dx.doi.org/10.1108/ijem-09-2015-0122.
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Purpose The purpose of this paper is to provide an analysis of specific learning outcomes in an undergraduate commerce degree in a large research-intensive university in Australia. Design/methodology/approach It uses data collected from assurance of learning activities as part of Association to Advance Collegiate Schools of Business accreditation. A total of 267 assessments were marked using nine different rubrics in nine different subjects. It assessed six learning outcomes. Findings Results indicate that a number of skills deficits exist among commerce students’ application of mathematical tools, analysis of business issues or problems, demonstration and application of theories, models or concepts, describing alternative methods of analysis, and generating supported conclusions or solutions, and analysing the research of others. These findings tell us that there are a number of higher order thinking skills that students need to develop when they pursue a commerce degree. It also creates a challenge for universities to foster an environment where these skills are developed in the curriculum. Practical implications The wider implications to higher education include a reconsideration of the purpose of the commerce degree, the importance of feedback from various stakeholders (e.g. alumni, employers) to inform the commerce curriculum, and the range of learning experiences that develop these skills. More importantly, this study has identified specific skills deficits across the broad generic skills embedded in the commerce degree. It can assist academic staff and program managers in planning for future curriculum improvements as they see fit in the context of their own commerce programs. Originality/value This is a novel contribution in that it provides specific assessment of skills deficits in business undergraduate education.