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By E Y. Baafi

Artisanal and small-scale gold mining (ASSM) offers lucrative employment opportunities to the locals of most developing countries. The major drawback of ASSM is its adverse impacts on the environment resulting from improper mining and processing techniques. Papua New Guinea (PNG) has very active ASSM activities. The artisanal and small-scale gold mining in PNG provide employment at local and national levels and the sector is an important source for inflow of foreign exchange into rural communities. However, small-scale mining activities are associated with sensitive health and environmental issues. The process of recovering gold by retorting and heating the amalgam over an open fire is a dangerous health practice. This paper discusses artisanal and small-scale gold mining operations in PNG and their impacts on the local environment.

Jan 1, 2008

By R C. Owen, M A. Ward

The paper describes the application of New Zealand's environmental impact assessment procedures to a proposed gold and silver mine in the North Island of New Zealand. The project is described and a summary is provided of the statutory permits or consents that are required prior to operation of the project. Emphasis is given to the requirement for environmental impact assessment and the preparation of a formal environmental impact report. The company's approach to impact assessment is described, with examples of how this assessment and the identification of management alternatives influenced the engineering design of the project. This paper was prepared as a contribution to a working session of the International Association of Impact Assessment VII Annual Conference, July 1988.

Jan 1, 1988

Studies of the minor element content of sphalerite and pyrite have generally been concerned with individual deposits or localised groups of deposits. However, a small number of more regional investigations have been reported (e.g. Davidson, 1962; Groves and Loftus-Hills, 1968; Loftus-Hills and Solomon, 1967; Price, 1972; Bralia et al., 1979) which have used the minor element abundances to evaluate the petrogenesis and geological affinities of diverse ore types and to fingerprint metallogenic provinces (e.g. Ivanov, 1964). While generally held to be valid, some doubts have nevertheless been cast on the reliability of minor element abundances in petrogenetic deliberations (e.g. Mercer, This paper reports on the distribution of he. Cpl and Mn in sphalerite, and Co, Ni and Mn in pyrite, from sulphide mineral occurrences within the "eugeosynclinal" prism comprising the New England Region of north-eastern New South Wales and south- eastern Queensland (Fig. 1). The occurrences examined are representative of two well-defined styles of mineralisation (Stanton et al., 1974) within which clear patterns of ore-rock distribution give rise to specific metal associations (Herbert. 1977).

Jan 1, 1987

By Lauha E. A

The Goldstrike Mine is in Eureka County, Nevada, U.S.A., approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora Mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike subdistrict of the Carlin Trend, a northwest alignment of sediment hosted, disseminated gold deposits. The Carlin Trend includes over 15 major gold deposits with production, reserves and geological resources of approximately 65 million ounces of gold (Figure 1). In the Bluestar/Goldstrike subdistrict, there are seven major deposits; Betze, Lower Post, Post, Genesis, Bluestar, Purple Vein and Deep Star, plus numerous smaller deposits (Figure 2). Production, reserves and resources for the subdistrict are approximately 40 million ounces. Betze and Purple Vein are located on property controlled by Bamck Goldstrike Mines and Bluestar and Genesis on Newmont Gold property. Post, Lower Post, and Deep Star occur both on Barrick and Newmont Property.

Jan 1, 1991

By El-Ansary M

Estimation of in-situ resources and recoverable ore reserves for the Boddington Gold Mine feasibility study was done by applying an essentially "classical" ore reserve method. This relied completely on customized graphics-based computer software requiring close co-operation and interaction between geologists and mining engineers. All geological and mining outlines were interpreted and digitized manually. Classification of selectively mineable reserves into ore, marginal and waste categories was done using a method involving convolution, devised by Dr S Carras of the Systems Research Institute of Australia, and Mr R Hooper of Kinhill Stearns. The estimation process was complicated by the frequently conflicting requirements of the various joint venture partners. The resulting ore reserve figures therefore satisfied only the most general expectations of each partner.

Jan 1, 1987

Conventionally, a combined system consist- ing of a dry or wet pulverizer and kneading mac- hine is applied to the pretreatment of fine mat- erials for agglomeration, especially for pellet- izing. However, treatment cannot be expected to be satisfactory owing to the complexities of the process. A new process was developed to over- come the defects inherent in the conventional process. This new process treats certain fine materials having a moisture content somewhat lower than that suitable for pelletizing in a ball or rod mill. The mill is of special de- sign in which grinding and strong kneading are performed to give an extremely homogeneous ball- ing material with appropriate size distribution and pelletizing characteristics. The most serious problem in this process is the choking of sticky materials in the mill. A specially designed rubber lining was installed in the mill to overcome this trouble. This paper presents actual results from our iron ore pelletizing plant relating to the pelletization of other fine materials.

Jan 1, 1974

Silica-Kaolin Sand Wet Sizing The Bulgarian deposits of silica-kaolin sand are localised in the eastern part of the Danube plain. After wet separation the raw material yields two products - washed kaolin (different grades) and silica sand (different grades). The water washing technology includes: disintegration; spiral classification; hydrocyclone classification and dewatering of kaolin grades; hydroclassification; sizing using drum screens and dewatering of silica sand grades. Research and development program has started to improve the silica-kaolin sand separation in processing plants. Based on the raw material and tails characterisation data and the preliminary experiments using Derrick Stacksizer screening machines a silica-kaolin sand wet sizing technology was developed. The full-scale pilot flowsheet includes the following units: Derrick Stacksizer equipped with 0.43 mm opening Derrick Urethane Panel; 500 mm Flat bottom Hydrocyclone; Derrick Stacksizer equipped with 0.150 mm opening Derrick Urethane Panel; 100 mm Hydrocyclone and Derrick Dual Motor Linear Motion Machine equipped with 0.064 mm opening Derrick Pyramid Panel. The pilot-test data clearly demonstrate that the new silica-kaolin sand wet sizing technology is suitable for Bulgarian silica-kaolin raw material. There are possibilities to increase the silica sand recovery increasing the production of silica sand grade PK 0.16 and starting the production a new grade PK 0.10.

Sep 13, 2010

By M Ridd

The Pasminco Century Mine (PCML) is located 250 kilometres north-north-west of Mt Isa in Queensland. As one of the worldÆs largest zinc mines, PCML comprises mining and milling operations at Lawn Hill, concentrate filtering and shipping facilities at Karumba in the Gulf of Carpentaria, and a 304 km slurry pipeline connecting the two operations.Mineralisation at Century occurs in the upper part of the Lawn Hill formation and is comprised of siltstones, shale and sandstone. Pyrite occurs immediately above the mineralised sequence, and throughout the footwall carbonaceous shale forming the lower proportion of the deposit. Zinc predominantly occurs as sphalerite (ZnS) and lead as galena (PbS). These sulfides are very fine-grained and may oxidise rapidly upon exposure. The pyrite, sphalerite and galena are the main potential sources of acid rock drainage (ARD) or heavy metal leachate at the mine site.To minimise the generation of ARD in the waste rock dumps, they are constructed in a specific manner and waste rock is classified into the following three classes based on competence and acid forming/consuming capabilities:Class 1: Competent rock, non-acid forming or acid-consuming material. Class 2: Non-competent, non-acid forming or acid-consuming material. Class 3: Acid-forming material. The generalised Waste Rock Dump Design for current operations comprises an outer zone of Class 1 material and inner zone with Class 2 and 3 material. Limestone is the Class 1 material used for both its structural support and acid neutralising capacity. Reserves of limestone at the mine site are limited. Net acid generation (NAG) tests confirm that a mix of limestone and shales can be net acid consuming.Field based and laboratory based trials have been established at PCML to quantify blending levels of limestone and shale that will produce leachates both neutral in pH and low in metal/salt concentrations. This paper will discuss the first six months results (of a two-year sampling program) from the trials.

Jan 1, 2004

All companies and individuals who embark on a business venture incur costs. For the most part these costs can be conveniently categorised, firstly into capital and operating costs and then into the various elements of these major cost centres. Although the nature of expenditure naturally differs as between industries certain broad cost types are characteristic of all heavy industries. The capital costs of gaining access to an orebody, equipping a new mine, building a treatment plant and perhaps refining and smelting facilities are likened to capital expenditure by a manufacturer on new plant and equipment required for an expansion or new product innovation. Similarly the day to day costs of labour and materials employed in the running of a mining operation can be likened to similar costs in other heavy industry. There is another group of costs that are not so easily categorised. Most industries incur unavoidable costs that do not form part of the direct or capital costs of physical production. These costs include taxes and other payments to government and research expenditure. The mining industry has a particularly heavy burden of non-production costs and it is the objective here to highlight and analyse a few of them. These costs are exploration expenditure, infrastructure expenditure, royalties and income tax. This is not to suggest that these are the only major non-production costs that the mining industry needs to bear. The industry may incur significant costs for environment protection, land tenure maintenance and on liaising with Government on a wide variety of matters. It is for reasons of subject manageability that the list is confined to the four costs mentioned. For the mining industry, exploration and infrastructure expenditure, royalties and income tax have several distinguishing features. Firstly, they are generally proportionately large costs. Exploration and infrastructure expenditure for example, could well exceed mine development costs. Depending on how royalties are levied, they may be very high in relation to profits earned and many in fact exceed profits. Secondly, except for income tax, they are costs that are generally not payable by other industries. Exploration expenditure is in some respects comparable with industrial research and development. However, because mines are wasting assets exploration is necessary for survival, and it is likely to form a larger part of costs per dollar of profits or sales than R&D. It can therefore be said that exploration is of far more significance to the miner than R&D is to the typical industrial company. Furthermore, unlike exploration expenditure, R&D results are transportable and patents permitting, transferable. The infrastructure burden that miners must carry is unique to the industry. Whereas urbanised industry is not usually liable for the capital cost of power, water, transport, townships and community facilities, the miner must finance these projects himself. Neither the payment of royalties, nor of course, income tax are unique to the mining industry. Royalties are more properly described as a unique charge on some primary industries but however described, they are a charge that manufacturing and service industries do not have to pay. Whilst we all pay income tax, the mining industry's uniqueness derives from the special problem that the industry has in arriving at annual net income in view of the capital intensity of the industry, partly due to expenditure on infrastructure, the indefinite life of capital equipment and its unpredictable residual value, funds expended on exploration and long lead times associated with a mine development. The third distinguishing feature of these costs is that, with the possible exception of exploration expenditure, they are heavily influenced by the policies and actions of Government. As such the industry has a responsibility to promote the industry by emphasising its potential to improve national product including exports and by requesting that the Government provide for the industry in its long term planning and seek its co-operation to prevent the industry incurring inequitable penalties relative to other industries.Finally, exploration and infrastructure expenditure are significant because they are front-end charges on a project. When due allowance is given the time value of money and the deferment of income from a mining development to which they relate, exploration and infrastructure expenditure assume greater importance than the raw money expenditure suggests. For all these reasons, exploration and infrastructure expenditure, mining royalties and mining income tax are worthy of detailed study. This is the purpose of this paper. The objective is to examine the determinants that give rise to them and provide some thoughts on their impact on on-going and potential mining developments and, where relevant, to make some suggestions as to how they may be minimised.

Jan 1, 1977

By Alder KF

Nuclear power stations to be installed in Australia will be fuelled from Australian resources of raw materials. This will require the establishment of new manufacturing industries and the eventual expansion of established activities, especially in uranium mining and the preparation of precision metal products. This paper presents some predictions of the possible growth of nuclear power installations in Australia. These might amount to 4000 MWE by 1985 and 11,500 MWE by 1990 and towards the end of the century, about 50% of new generating plant might be nuclear. Predictions are given of the demands for materials (uranium and zirconium) and fuel manufacturing services for four reactor systems which might be considered in the programme. - The availability of raw materials and technical capability place Australia in a particularly good position to undertake the manufacture of nuclear fuel'; in addition to satisfying the domestic demand we should actively seek export markets for these products.

Jan 1, 1970

New South Wales mining legislation reinforces a systematic approach to safety management. It is now a requirement of all mines in the coal, metalliferous and quarrying sectors in NSW to prepare a Mine Safety Management Plan. The paper briefly outlines work currently being undertaken by the Safety Operations Branch of the NSW Department of Mineral Resources (DMR). The DMR is working proactively with NSW mines in the preparation and implementation of effective Mine Safety Management Plans. There is a growing realisation that a systematic approach to safety management, underpinned by the process of hazard identification, has real potential to improve safety in the workplace. The paper briefly describes the framework used in a current æmines education programÆ and its æduty of careÆ foundation. Particular attention is paid to the role of mining operators in the implementation of Mine Safety Management Plans and their expected behaviour in demonstrating compliance. One challenge is convincing some mining operators that they must adopt new ways of working. Safety Operations officers are often reminded of the need to translate Mine Safety Management Plans into practical safety systems during audits and inspections of mines and through investigations into accidents and incidents. To have a real effect on the mineÆs safety performance, using these systems must be a normal way of going about a dayÆs work for all persons who work at the mine: not a safety manual collecting dust on the mine managerÆs bookshelf. Mine Safety Management Plans are important to mining operators. Not only will positive involvement in the development and use of safety systems ensure they meet their obligations under mining legislation, but it will also help prevent themselves or their workmates being injured or killed.

Jan 1, 2002

By A Roshal

It is anticipated that many future uranium mines in Australia will be using the in situ leaching mining process. It is fair to say that close to one third of uranium production will be generated by this method, whilst the other two thirds will fall on the uranium generated from hard rock mining and other mining methods, such as traditional open cut mining. For other types of deposits the in situ leaching mining method will remain the best technological, commercial and environmental alternative. It is important to identify and prevent all risks involved in uranium mining. The expertise in this subject is limited. Over the years there was only one mine using the in situ leaching process for uranium extraction in Australia. Computer simulation of propagation of leachate during and after the uranium in situ leaching is a crucial factor, not only for addressing the environmental concerns, but also for the most efficient recovery of the deposit. The decontamination can be modelled for a period of up to 100 years, with the acid neutralisation forecast for a period of up to 400 years. The results of the modelling are paramount for definition of the reserves, efficiency of the mining method and the environmental impact statement. The accuracy of the hydrogeological modelling and carefully selected environmental management program enables a mining company to quantify and minimise the impact of the mining activities on the regional aquifer and to prevent environmental disasters. In the study, the completed hydrogeological model allowed the client, the authorities and the community to make an informed decision about the environmental impact of the in situ leaching of uranium. In particular, the model proved that neither during the mining, nor during the neutralisation the toxic elements would interact with the local catchment area.

Jan 1, 2008

Nuclear power stations to be installed in Australia will be fuelled from Australian resources of raw materials.This will require the establishment of new manufacturing industries and the eventual expansion of established activities, especially in uranium mining and the preparation of precision metal products.This paper presents some predictions of the possible growth of nuclear power installations in Australia.These might amount to 4000 MWE by 1985 and 11,500 MWE by 1990 and towards the end of the century, about 50 per cent of new generating plant might be nuclear.Predictions are given of the demands for materials (uranium and zirconium) and fuel manufacturing services for four reactor systems which might be considered in the programme.The availability of raw materials and technical capability place Australia in a particularly good position to undertake the manufacture of nuclear fuel; in addition to satisfying the domestic demand we should actively seek export markets for these products.

Jan 1, 1971

Amongst the Pacific Rim countries, Papua New Guinea (PNG) is the leader in new gold discoveries and developments leading to new production. PNG has shown a dramatic increase in gold production when taken from a base of about 600 000 ounces in 1984 to 1 160 000 ounces in 1986. 1987 is expected to produce about 1 500 000 ounces and new planned developments will give further large increases. PNG's leading position when compared with neighboring Pacific Rim countries is only partly due to its favorable geological setting along the "Rim of Fire" epithermal zone. More important have been well-thought-out mining development legislation and good administration as well as consistent taxation and royalty policies. A stable political environment and a track record of new mining developments over the last 15 years, both pre and post Independence in 1975, have also been important factors in encouraging the new developments. Early Portuguese explorers associated the New Guinea mainland with gold as early as 1525 but it was not un,11 1R77 that a small ill-fated gold rush gave the first recorded production at Laloki near Port Moresby. Modest but commercial discoveries were made in the outer islands and coastal mainland regions from 1888 to 1926. In 1922 William "Sharkeye" Park found gold at Edie Creek and this led to major discoveries at Wau and Bulolo which were the first large scale commercial gold Operations.

Jan 1, 1987

By D Trembath

"One of the key risks to the success of a mining operation is the accuracy of the estimates of both the economic mineral and any accompanying contaminants contained within the ore reserve. Misrepresenting the mineralogical characteristics of the ore reserve can result in considerable financial investment in an operation that is in fact uneconomic and/or carries a significant environmental risk. This in turn can result in an unplanned closure of the operation with associated financial, environmental and social legacy. One way to minimise this risk is to undertake high density resource sampling to gain a better understanding of the resource characteristics. However, such an approach is expensive, time-consuming and often impractical. The risk of not having an accurate model is typically assessed during a feasibility study utilising a Monte Carlo simulation method or some form of sensitivity analysis. Importantly, the error margins used in these types of analyses are often based on subjective or very general criteria such as ‘professional judgement’ or an ‘industry standard’. This presentation introduces a conditional simulation method for developing a range of mineralogical distribution models. Based broadly on the method outlined in Journel and Kyriakidis (2004) the proposed approach develops this work further. It combines a geostatistical analysis of the available data with automated mine design software to provide a rigorous method for assessing the confidence in the mineralogical characterisation of the ore reserve. The process is based on simulating possible mine plans based on the statistical characteristics of the available resource sample data. These plans are then assessed against high resolution resource models generated using a Sequential Gaussian Simulation method. The outcome is confidence intervals for important characteristics of the ore reserve estimate relative to the actual resource. These confidence intervals are an objective and transparent measure important for assessing closure risks and represent an improvement over common practice.CITATION:Trembath, D, 2016. A simulation approach for improving the assessment of closure risks, in Proceedings Life-of-Mine 2016 Conference , pp 36–38 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 28, 2016

By M Wilkes, C-Q Liu

Microbial oxidation of refractory sulphide ores (particularly gold and copper ores) are well-established techniques that are increasingly employed because of their low capital and operating costs and environmental benefits. CSIRO has established a multidivisional project, the æBioMineral Processing InitiativeÆ, with the goal of generating new and improved high temperature micro-organisms for biological oxidation of these refractory ores. The project is currently focused on the discovery/generation of novel hyperthermophiles for the bioleaching of copper from chalcopyrite. As part of this project we are investigating the practicalities of genetic modification of iron/sulphur oxidising micro-organisms. The molecular biology of iron/sulphur oxidising acidophiles is still in its infancy. This work is aimed at improving our knowledge of vectors, promoters, selectable markers, gene transfer and expression in these organisms. The Acidithiobacillus ferrooxidans genome is currently available and genomics is proceeding at a rate where in the next few years we can expect at least one or two relevant microbial genomes to be sequenced each year. New genes that impart useful characteristics to iron/sulphur oxidising acidophiles will be available from published genomes and the study of newly isolated hyperthermophiles. We need to be in a position to clone and express those genes. This paper will describe the isolation, transfer and expression of thiocyanate hydrolase genes in Escherichia coli and At. ferrooxidans. Most common antibiotics are not effective against iron/sulphur oxidising acidophiles. Also, the use of antibiotics or their resistance markers outside of a laboratory setting would not be appropriate. Resistance to thiocyanate should be a useful selectable marker, without implications for human or animal health. Additionally, thiocyanate resistant iron/sulphur oxidising acidophiles might have application in gold bio-oxidation plants in arid areas where reuse of contaminated tailings water is desirable. The cloning of thiocyanate genes in broad host range plasmids under the control of E. coli and At. ferrooxidans promoters and the expression and phenotypic effects in both species will be described.

Jan 1, 2002

By B Lyne

In 1990, the Queensland mining industry had come to the conclusion that new safety and health legislation based on risk identification and control was required if the mining industry was to be effectively and efficiently regulated. In particular stakeholders in the coal mining industry had arrived at this opinion after the industry had suffered a number of major underground explosions over the 14-year period between 1972 and 1986. Also by 1990, a general consensus had emerged across both the coal and metalliferous mining sectors that mining industry was over regulated and, more to the point this over regulation did not encourage industry to identify and address the underlying causes that had led to a cycle of major mining accidents in the state. The prevailing opinion was that the prescriptive legislation left the ownership of risk management with the regulator and not with the mine operator. This paper discusses the background to the development of the Queensland Coal Mining Safety and Health Act 1999 and the Mining and Quarrying Safety and Health Act 1999 and the progress made in improving safety and health since the statutes came into force on the 16 March 2001. The paper discusses the issues that had to be addressed during the development of the legislation including the interaction with other legislation based on based on risk management principles that either overly or interface with the mining legislation. The effect the underground explosion at Moura No 2 in 1994 had on the final content of the new legislation is also considered. Health is often the neglected twin of safety and health legislation and the paper previews the health surveillance system being proposed in Queensland to ensure that health of mine and quarry workers is afforded the same priority as their safety. By increasing the structured management of occupational health problems in our mines there is an opportunity to make significant improvements in mine safety In conclusion the paper reviews the results to date since the introduction of the new mining safety and health legislation in Queensland on the 16 March 2001. Progress has been made and more is yet to be achieved

Jan 1, 2003

Adsorption isotherms, zeta potential and coagulation techniques have been used to exa- mine the mechanism of metal activation on SiO2 and ZnS surfaces. The importance of surface nucleation or precipitation of metal hydroxide coatings is'established and identified-by characteristic charge reversal patterns. The significance of surface coatings in sulphide and non-sulphide flotation is discussed.

Jan 1, 1973

Over the past several years, copper prices have surged from under a dollar to over three dollars a pound. However, the long-run trend in real copper prices since at least the early 1970s has been sharply downward. While many now contend that the long-run trend in real copper prices is now upward, the result of structural changes in this market, others are sceptical. Nor is copper unique; the prices for a number of other metals, including aluminium, iron ore, lead, nickel and zinc, have followed similar patterns. This paper examines the forces behind short-run and long-run trends in metal prices. It first focuses on the short run, where it argues that shifts in demand are largely behind changes in prices. It then turns to the long run, where it concludes that production costs and supply largely govern price trends. Finally, it explores several implications of these findings, including those for diversification and market risk, for forecasting mineral prices, for assessing the growth of metal demand in China and elsewhere on metal prices, and for changes in the long-run price trends.

Jan 1, 2006

The implementation of robust, reliable and accurate sampling systems is the key to the successful management of any mineral processing plant. The representative sampling of a mineral processing plant is the only way to determine what is coming into the plant, what is going out as fi nal product and what is going to tails. In plants with high gravity gold components, where high recovery effort gravity circuits are installed, the use of a gravity recoverable gold (GRG) sampling system can assist in the online monitoring of the performance of the circuit. The typical installation location would be in CIP or fl otation feed (ie cyclone overfl ow), downstream of the gravity circuit. A GRG sampling system generally consists of the following equipment: true proportional, continuous drive, linear cross cut sampler, secondary vezin sampler operated on a timer, a batch centrifugal concentrator, and sample dewatering module. The operating philosophy of the GRG sampling system is that the primary sampler operates on a continuous basis, generating a constant stream of truly representative sample. Consep's H&S drive system is unique in its ability to be able to operate in a continuous mode, therefore enabling a continuous stream of representative sample to be generated. The primary sample stream reports to the secondary sampler. The secondary sampler operates on an intermittent basis (nominally ten minute interval), resulting in a relatively small sample volume per shift. Normally the sample volume would be ten to 15 L per shift. The secondary sample rejects stream reports back to the batch centrifugal concentrator. The sample generated from the secondary sampler can be dewatered using a Consep H&S dewatering module. This device produces a final sample that consists of separate filter cake and filtrate. These are suitable for taking directly to the laboratory. The continuous stream of truly representative secondary sampler rejects is passed through an appropriately sized Knelson Concentrator, typically a KCMD7, KCCD10 or KCCD12 sized unit. This unit recovers any available GRG from the stream. The Knelson Concentrator is also purged of its gravity concentrate at the end of the shift. This sample, which is nominally around 1 - 2.5 kg of concentrate, is also taken to the laboratory. At the end of the shift the client will have a measure of the gravity recoverable gold content of the target slurry stream, as well as a true representative sample of the complete stream. Through the addition of a Knelson Concentrator to an otherwise typical sample station, it is possible to generate a true measure of the performance of your gravity circuit. This will take the guess work out of the daily variation in gravity circuit gold recovery, as the site knows whether the changes are due to gravity circuit equipment performance, or due to the natural variation of ore GRG contents. Maintenance planning can also be designed around the system, as the site will have a composite sample to measure the performance of the circuit, therefore indicating where performance has dropped and maintenance is needed. This is an ABSTRACT ONLY. No paper was prepared for this presentation.

Aug 1, 2010