1,720,998 research outputs found
Fishy tales: Behaviour of schooling fish escaping from terns
No full textThe aim of this study is to develop a better understanding of seabird foraging behaviour and the anti-predator behaviour of their prey. Studies of seabirds’ foraging and prey-capture behaviour, as it relates to the evasive and escape behaviour of schooling fish, are sparse. Our study was carried out at One Tree Reef on the southern end of the Great Barrier Reef, Australia. A school of hardyheads Pranesus capricornensis sheltered in the shallows over the sand flats in front of the research station for 14 non-consecutive days. In that time, Lesser Crested Terns Thalasseus bengalensis were observed for 10 hours from above the surface in 37 foraging bouts and for 40 minutes from underwater in at least one foraging bout. In each foraging bout, a single tern dived into the school. We found that terns on average dived at a rate of 0.67 ± 0.35 dives/minute from 4–5 m above the surface. The depth range of dives was 43–58 cm. Therefore, fish within 58 cm of the surface were potentially accessible. The total length of the hardyheads was 10–12 cm, which is within the size range useable by terns. Fish used flash expansion to escape diving terns and formed a vacuole around birds as they slowly ascended to the surface. This escape manoeuvre was effective about 80% of the time. The fish that were caught did not respond to the escape movements of the fish above them and, therefore, were isolated. Fish also used the C-startle response to escape terns underwater and in mid-air. The anti-predator manoeuvres of hardyheads are similar to those observed among Clupea spp. (herrings and sardines) and Ammodytes spp. (sand eels) escaping sub-surface predators. Hardyheads and sardines react in the same way to gannets Morus spp. and terns that plunge dive directly to their prey, partially confirming the prediction that results for plunge-diving gannets are generalisable to other gannets and boobies (Sula spp.), terns and gulls (Larus spp.), tropicbirds (Phaethon spp.), pelicans (Pelecanus spp.), and kingfishers (Alcedinidae).Full Tex
Financial investments in the global water market
Get PDFThis chapter examines the relationship between the water sector of the equity markets. It includes the world market and markets of different individual countries such as China, Hong Kong, Singapore, Germany, France, the UK, Brazil, Chile, and the US for the period 2001-2020. Investment returns and volatility of these markets are analyzed to understand investment decision-making in these water markets. The OLS and quantile regressions show that China, Hong Kong, Singapore, Germany, France, the UK, Brazil, Chile, and the US are positively related to the world market. The results confirm simultaneous interactions between the world market and the other nine markets. The ARMA (1,1)-GARCH (1,1) model shows a high degree of persistency in the conditional volatility of stock returns for these water markets which means "explosive" volatility. Moreover, the VAR analyses show that the nine markets positively and negatively affect the world market. The findings may assist the international institutions while deciding investment in water portfolios.Full Tex
Volatility spillovers in water exchange-traded funds
No full textWater is one of the planet's essential and extensively used resource. However, it is predicted that around 3.2 billion people will face severe water shortages by 2030. Hence, there is an urgent need to expand water utilities, water infrastructure, and water treatment plants to maximally protect water resources. Investment in water is essential for supporting this cause, and private funding is a way to meet the financial needs of the water industry. This study examines returns and volatility of four water exchange-traded funds (ETFs). Using the GARCH, EGARCH, and TGARCH models, this study shows the existence of persistence of volatility among the four water ETFs at the 1% level. The analyses and results of this study show important implications for investors and stakeholders, enabling them to make appropriate decisions.Full Tex
The determinants of capital structure: Evidence from the global water industry
No full textWater may be our most basic and precious resource. However, climate change and severe weather extremes affect water resources around the world in coming years. As changing climate had led to water shortages in many places, there is an urgently need to expand water utilities, water infrastructure and water treatment plants while protecting water resources as well. Thus, investment in water is critical and private funding is a proper way to meet the financial needs in the water industry. In this book chapter, we examine the determinants of capital structure of 72 private water companies (water utilities, water infrastructure and water treatment plants) that comprise the 4 water indices (WOWAX, S-NET, S&P and MSCI ACWI) over the world for the period of 2004-2014 using unbalanced panel (fixed effects) regression model for the financing decision focuses. The eight attributes' variables (Profitability, size, age, risk, free cash flows, tangibility asset, non-debt tax shield and growth opportunity) are used to explain the capital structure (Leverage, long-term debt to asset and short-term debt to asset. This study uses unbalanced panel (fixed effects) regression model. Our results show that these eight attributes' variables positively and negatively impact on capital structure at the 1%, 5% and 10% levels of significance, respectively. The findings would be useful to higher level executives of water companies' who may tend to favour optimal capital structure to increase the profitability and thus distribute more dividends to shareholders than other variables.Full Tex
Impact of solar and wind prices on the integrated global electricity spot and options markets: A time series analysis
No full textFollowing the liberalisation of the global electricity markets, spot and options markets have been established in many countries. Electricity pricing issues, coupled with increased concern regarding global warming and the greenhouse effect, represent the driving factors behind electricity price movements. Australia, Germany, the United States (US) and other countries worldwide have increasingly shifted their focus away from fossil fuels and towards energy generated from renewable sources, including solar and wind power. This paper examines the behaviour of the Australian, German and US electricity markets in terms of the impact of solar and wind pricing on the electricity spot and options markets for the period January 2006 to March 2018. Using a vector autoregression analysis, we examine both the direction of influence and the influence absorption through Granger causality testing, the impulse response function and forecast error variance decompositions. Our findings indicate that the electricity markets in Australia, Germany and the US are interdependent and related with regards to solar and wind price changes, meaning that the investigated electricity markets are influenced by movements in other electricity markets. The findings of this study are important for investors, energy analysts, government organisations and policymakers.Full Tex
Application of autoregressive integrated moving average modelling for the forecasting of solar, wind, spot and options electricity prices: The australian national electricity market
No full textThis study aims to develop autoregressive integrated moving average (ARIMA) models to predict the solar, wind, spot and options pricing over the next two years, with historical data being used in a univariate manner to understand market behaviour in terms of trends. The assessment is made in the context of the Australian National Electricity Market (ANEM). The ARIMA models predict the future values of the monthly solar, wind, spot and options prices for various Australian states using time-series data from January 2006 to March 2018. The results show increases from 30.46–40.42% for the spot electricity prices and from 14.80–15.13% for the options electricity prices in the ANEM with a two-year horizon. The results further show that wind prices are expected to increase by an average of 5.43%. However, the results also show that the average solar electricity prices will decrease by 67.7%.Full Tex
Impact of the nature of energy management and responses to policies regarding solar and wind pricing: A qualitative study of the australian electricity markets
No full textThe present study employed various qualitative techniques to investigate the nature and influence of policies and regulations concerning solar and wind pricing on the Australian electricity spot and options markets. The analysis was based on data gathered through interviews conducted with energy managers, chief executive officers and other significant personnel from the Australian electricity industry. The interviewees’ responses regarding the solar and wind policies of relevance to the Australian electricity markets were examined, and the thick and in-depth content data derived from the interviews were used to examine how their views and personal politics influenced pricing within the electricity markets. The results suggest that renewable energy policies lower the electricity prices, reduce the risks for investors and also result in larger deployment mechanisms.Full Tex
Assessing the effects of solar and wind prices on the australia electricity spot and options markets using a vector autoregression analysis
No full textThis paper examines the impact of solar and wind prices on the Australian electricity spot and options markets for the period January 2006 to March 2018. Using a vector autoregression analysis, we examine both the direction of influence and influence absorption through Granger causality testing, the impulse response function, and forecast error variance decompositions. We identify a unidirectional Granger causal relationship between the solar and wind electricity prices and the spot prices in New South Wales, Queensland, Victoria, and South Australia. The forecast results suggest that the solar and wind electricity prices reduce the spot and options electricity market prices. These results are important for energy policymakers and government organizations that support renewables, as their use not only decreases the wholesale spot prices, but also encourages initiatives to explore and switch to alternative energy sources, which tend to be more cost effective and environmentally friendly.Full Tex
Vedas and the Development of Arithmetic and Algebra
No full textProblem statement: Algebra developed in three stages: rhetorical or prose algebra, syncopated or abbreviated algebra and symbolic algebra-known as "school algebra". School algebra developed rather early in India and the literature now suggests that the first civilization to develop symbolic algebra was the Vedic Indians. Approach: Philosophical ideas of the time influenced the development of the decimal system and arithmetic and that in turn led to algebra. Indeed, symbolic algebraic ideas are deep rooted in Vedic philosophy. The Vedic arithmetic and mathematics were of a high level at an early period and the Hindus used algebraic ideas to generate formulas simplifying calculations. Results: In the main, they developed formulas to understand the physical world satisfying the needs of religion (apara and para vidya). While geometrical focus, logic and proof type are features of Greek mathematics, "boldness of conception, abstraction, symbolism" are essentially in Indian mathematics. From such a history study, a number of implications can be drawn regarding the learning of algebra. Real life, imaginative and creative problems that encourage risk should be the focus in student learning; allowing students freely move between numbers, magnitudes and symbols rather than taking separate static or unchanging view. A move from concrete to pictorial to symbolic modes was present in ancient learning. Real life practical needs motivated the progress to symbolic algebra. The use of rich context based problems that stimulate and motivate students to raise levels higher to transfer knowledge should be the focus of learning. Conclusion/Recommendations: The progress from arithmetic to algebra in India was achieved through different modes of learning, risk taking, problem solving and higher order thinking all in line with current emphasis in mathematics education but at rather early stage in human history.Griffith Sciences, Griffith School of EnvironmentFull Tex
Relationship between El Niño southern oscillation index and rainfall (Queensland, Australia)
No full textThis paper explores the relationship between El NiᯠSouthern Oscillation Index (SOI) and rainfall in South East Queensland. Several statistical models of the SOI and rainfall data are analysed including interactions. The results of the analyses show that although the SOI and rainfall can be predicted for short terms using time series analysis methods, mean squared error (MSE) and Theil's U showed that in comparison to persistence model forecasts may not be significantly better. Although the short term predictions may be worse, this does not mean that these cannot be used; rather, it shows that for different fitting and forecast periods, models can fail in predicting ahead. In fact weather forecasts can predict the short term rainfall well - but cannot predict monthly precipitation for two or three or more months ahead. In climate predictions the limit of predictability is reached when the standardised MSE reaches the climate variance (=1). All the rainfall models used in this study show an MSE well below 1, i.e. the models did not reach the limit of predictability.Griffith Sciences, Griffith School of EnvironmentFull Tex
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