Vista University

About: Vista University is a based out in . It is known for research contribution in the topics: Boron trifluoride & Higher education. The organization has 225 authors who have published 336 publications receiving 3345 citations.

Contributions to the mathematics of the nonstandard finite difference method and applications

Abstract: We formalize the transfer of essential properties of the solution of a differential equation to the solution of a discrete scheme as qualitative stability with respect to the properties. This permits us to motivate some rules (viz. on the order of the difference equation, on the renormalization of the denominator of the discrete derivative, and on nonlocal approximation of nonlinear terms) used in the design of nonstandard finite difference schemes. Extensions of some models are considered, and numerical examples confirming the efficiency of the nonstandard approach are provided. © 2001 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 17: 518–543, 2001

Measuring associations between working capital and return on investment

Abstract: The two conflicting goals of working capital management are profitability and liquidity. This article looks at return on investment as a measure of profitability and some traditional and more recently developed working capital concepts as liquidity measures. Associations were measured between profitability and the liquidity concepts by using chi-square analysis and stepwise forward regression. The statistical test results showed that a traditional working capital leverage ratio, current liabilities divided by funds flow, displayed the greatest associations with return on investment. Well-known liquidity concepts such as the current and quick ratios registered insignificant associations whilst only one of the newer working capital concepts, the comprehensive liquidity index, indicated significant associations with return on investment.

The relationship between land use and soil erosion in the communal lands near Peddie town, Eastern Cape, South Africa

Abstract: The origins and development of severe forms of erosion are traced in the communal villages located in a part of the dividing ridge between the Great Fish and Keiskamma rivers near Peddie town, Eastern Cape, South Africa. Progressive changes in land use and soil erosion distribution are reconstructed by analysing sequential aerial photographs of the area between 1938 and 1988. The distributions of the two phenomena are mapped and quantified at the different dates using PC ARC/INFO GIS. Observable soil erosion is confined to the communal lands at all the dates. Widespread abandonment of cultivated fields between 1965 and 1988 is noted as the most significant aspect of land use change in the communal lands. Gully initiation and intensification appear predominantly from the mid-1970s, coinciding with a period of extreme rainfall events. A close spatial correlation between abandoned cultivated land and severe gullies is identified. The research raises questions regarding both the cause for land abandonment and the reasons for its vulnerability to erosion. The observed land degradation is seen as the result of a complex interaction of social, economic and environmental factors which lead to land abandonment and its consequent erosion. Copyright © 2002 John Wiley & Sons, Ltd.

Debunking the myth of overgrazing and soil erosion

Abstract: What is overgrazing? Does it cause soil erosion? The recent debate from the ecological literature is reviewed as background to the debate on overgrazing and soil erosion. This debate stresses the need to view dryland grazing systems as dynamic ecosystems driven more by rainfall events than by livestock numbers. The case for soil erosion is then examined. Two case studies from communal rangelands in the Eastern Cape, South Africa, have cast doubts on the conventional wisdom that overgrazing leads to soil erosion. The first, a study of historical land-use change and erosion in a communal area, showed that the most intense erosion, taking the form of steeply dissected badlands, was associated with cultivated land that had been abandoned and reverted to grazing from the 1960s onwards. Such severe erosion was generally absent from land that had been under grazing since the 1930s. The second study demonstrated that erosion rates from communal grazing lands (‘overgrazed’) were only slightly higher than those from land under ‘optimal’ grazing, that is grazing at a level considered not to exceed the carrying capacity of the land. These results support the ecologist's contention that communal grazing systems do not necessarily degrade the range condition relative to management systems based on a notional carrying capacity. Copyright © 2004 John Wiley & Sons, Ltd.