Modelagem de dados de entrada para simulação estocástica de lavra

Mine simulation depends on data that is both coherent and representative of the mining operation. This paper describes a methodology for modeling operational data which has been developed for mine simulation. The methodology has been applied to a case study of an open-pit mine, where the cycle times of the truck fleet have been modeled for mine simulation purposes. The results obtained have shown that once the operational data has been treated using the proposed methodology, the system variables have proven to be adherent to theoretical distributions. The research indicated the need jar tracking the origin of data inconsistencies through the development of a process to manage inconsistent data from the mining operation.

Evaluation of citrus somatic hybrids for tolerance to Phytophthora nicotianae and citrus tristeza virus

Somatic hybridization is a biotechnology tool that can be used in citrus breeding programs to produce somatic hybrids with the complete genetic combination of both parents. The goal of this work was to test the reaction of citrus somatic hybrids that may be useful as rootstocks to trunk and root infections caused by Phytophthora nicotianae van Breda de Haan (P parasitica Dastur) and to citrus tristeza virus (CTV). The somatic hybrids evaluated were `Caipira` sweet orange (Citrus sinensis L. Osbeck) + `Rangpur` lime (C. limonia Osbeck), `Caipira` sweet orange + `Cleopatra` mandarin (C. reshni hort. ex Tanaka), `Caipira` sweet orange + `Volkamer` lemon (C. volkameriana V Ten. & Pasq.), `Caipira` sweet orange + rough lemon (C. jambhiri Lush.), `Cleopatra` mandarin + `Volkamer` lemon, `Cleopatra` mandarin + sour orange (C. aurantium L.), `Rangpur` lime + `Sunki` mandarin (C. sunki (Hayata) hort. ex Tanaka), `Ruby Blood` sweet orange (C. sinensis L. Osbeck) + `Volkamer` lemon, `Rohde Red` sweet orange (C. sinensis L. Osbeck) + `Volkamer` lemon, and `Valencia` sweet orange + Fortunella obovata hort. ex Tanaka. For P. nicotianae trunk and root infection assays, plants of the somatic hybrids, obtained from 9-month semi-hardwood cuttings, were evaluated and compared with diploid citrus rootstock cultivars after mycelia inoculation in the trunk or spore infestation in the substrate, respectively. `Cleopatra` mandarin + sour orange, `Rangpur` lime + `Sunki` mandarin, `Cleopatra` mandarin + `Volkamer` lemon, `Ruby Blood` sweet orange + `Volkamer` lemon, `Rohde Red` sweet orange + `Volkamer` lemon, and `Caipira` sweet orange + `Volkamer` lemon had less trunk rot occurrence, whereas the somatic hybrids `Cleopatra` mandarin + `Volkamer` lemon, `Cleopatra` mandarin + sour orange, `Caipira` sweet orange + `Volkamer` lemon, and `Caipira` sweet orange + `Rangpur` lime were tolerant to root rot. For CTV assays, plants of the somatic hybrids along with tolerant and intolerant rootstocks were budded with a mild strain CTV-infected or healthy `Valencia` sweet orange budwood. Differences in average scion shoot length indicated that the hybrids `Cleopatra` mandarin + sour orange and `Valencia` sweet orange + Fortunella obovata were intolerant to CTV (c) 2007 Elsevier B.V. All rights reserved.

Instantaneous outbursts in underground coal mines: An overview and association with coal type

Instantaneous outbursts in underground coal mines have occurred in at least 16 countries, involving both methane (CH4) and carbon dioxide (CO2). The precise mechanisms of an instantaneous outburst are still unresolved but must consider the effects of stress, gas content and physico-mechanical properties of the coal. Other factors such as mining methods (e.g., development heading into the coal seam) and geological features (e.g., coal seam disruptions from faulting) can combine to exacerbate the problem. Prediction techniques continue to be unreliable and unexpected outburst incidents resulting in fatalities are a major concern for underground coal operations. Gas content thresholds of 9 m(3)/t for CH4 and 6 m(3)/t for CO2 are used in the Sydney Basin, to indicate outburst-prone conditions, but are reviewed on an individual mine basis and in mixed as situations. Data on the sorption behaviour of Bowen Basin coals from Australia have provided an explanation for the conflicting results obtained by coal face desorption indices used for outburst-proneness assessment. A key factor appears to be different desorption rates displayed by banded coals, which is supported by both laboratory and mine-site investigations. Dull coal bands with high fusinite and semifusinite contents tend to display rapid desorption from solid coal, for a given pressure drop. The opposite is true for bright coal bands with high vitrinite contents and dull coal bands with high inertodetrinite contents. Consequently, when face samples of dull, fusinite-or semifusinite-rich coal of small particle size are taken for desorption testing, much gas has already escaped and low readings result. The converse applies for samples taken from coal bands with high vitrinite and/or inertodetrinite contents. In terms of outburst potential, it is the bright, vitrinite-rich and the dull, inertodetrinite-rich sections of a coal seam that appear to be more outburst-prone. This is due to the ability of the solid coal to retain gas, even after pressure reduction, creating a gas content gradient across the coal face sufficient to initiate an outburst. Once the particle size of the coal is reduced, rapid gas desorption can then take place. (C) 1998 Elsevier Science.

Nitrogen relations of natural and disturbed plant communities in tropical Australia

Nitrogen relations of natural and disturbed tropical plant communities in northern Australia (Kakadu National Park) were studied. Plant and soil N characteristics suggested that differences in N source utilisation occur at community and species level. Leaf and xylem sap N concentrations of plants in different communities were correlated with the availability of inorganic soil N (NH4+ and NO3-). In general, rates of leaf NO3- assimilation were low. Even in communities with a higher N status, including deciduous monsoon forest, disturbed wetland, and a revegetated mine waste rock dump, levels of leaf nitrate reductase, xylem and leaf NO3 levels were considerably lower than those that have been reported for eutrophic communities. Although NO3- assimilation in escarpment and eucalypt woodlands, and wetland, was generally low, within these communities there was a suite of species that exhibited a greater capacity for NO3- assimilation. These high-NO3- species were mainly annuals, resprouting herbs or deciduous trees that had leaves with high N contents. Ficus, a high-NO3- species, was associated with soil exhibiting higher rates of net mineralisation and net nitrification. Low-NO3- species were evergreen perennials with low leaf N concentrations. A third group of plants, which assimilated NO3- (albeit at lower rates than the high-NO3- species), and had high-N leaves, were leguminous species. Acacia species, common in woodlands, had the highest leaf N contents of all woody species. Acacia species appeared to have the greatest potential to utilise the entire spectrum of available N sources. This versatility in N source utilisation may be important in relation to their high tissue N status and comparatively short life cycle. Differences in N utilisation are discussed in the context of species life strategies and mycorrhizal associations.

Virtual models of the HLA class I antigen processing pathway

Antigen recognition by cytotoxic CD8 T cells is dependent upon a number of critical steps in MHC class I antigen processing including proteosomal cleavage, TAP transport into the endoplasmic reticulum, and MHC class 1 binding. Based on extensive experimental data relating to each of these steps there is now the capacity to model individual antigen processing steps with a high degree of accuracy. This paper demonstrates the potential to bring together models of individual antigen processing steps, for example proteosome cleavage, TAP transport, and MHC binding, to build highly informative models of functional pathways. In particular, we demonstrate how an artificial neural network model of TAP transport was used to mine a HLA-binding database so as to identify H LA-binding peptides transported by TAP. This integrated model of antigen processing provided the unique insight that HLA class I alleles apparently constitute two separate classes: those that are TAP-efficient for peptide loading (HLA-B27, -A3, and -A24) and those that are TAP-inefficient (HLA-A2, -B7, and -B8). Hence, using this integrated model we were able to generate novel hypotheses regarding antigen processing, and these hypotheses are now capable of being tested experimentally. This model confirms the feasibility of constructing a virtual immune system, whereby each additional step in antigen processing is incorporated into a single modular model. Accurate models of antigen processing have implications for the study of basic immunology as well as for the design of peptide-based vaccines and other immunotherapies. (C) 2004 Elsevier Inc. All rights reserved.

Trialing wetlands to treat coal mining wastewaters in a low rainfall, high evaporation environment

The large number of wetlands treating mining wastewaters around the world have mostly been constructed in temperate environments. Wetlands have yet to be proven in low rainfall, high evaporation environments and such conditions are common in many parts of Australia. BHP Australia Coal is researching whether wetlands have potential in central Queensland to treat coal mining wastewaters. In this region, mean annual rainfall is < 650 mm and evaporation > 2 000 mm. A pilot-scale wetland system has been constructed at an open-cut coal mine. The system comprises six treatment cells, each 125 m long and 10 m wide. The system is described in the paper and some initial results presented. Results over the first fourteen months of operation have shown that although pH has not increased enough to enable reuse or release of the water, sulfate reduction has been observed in parts of the system, as shown by the characteristic black precipitate and smell of hydrogen sulfide emanating from the wetlands. These encouraging signs have led to experiments aimed at identifying the factors limiting sulfate reduction. The first experiment, described herein, included four treatments where straw was overlain by soil and the water level varied, being either at the top of the straw, at the top of the soil, or about 5 cm above the soil. The effect of inoculating with sulfate-reducing bacteria was investigated. Two controls were included, one covered and one open, to enable the effect of evaporation to be determined. The final treatment consisted of combined straw/cattle manure overlain with soil. Results showed that sulfate reduction did occur, as demonstrated by pH increases and lowering of sulfate levels. Mean pH of the water was significantly higher after 19 days; in the controls, pH was < 3.3, whereas in the treatments, pH ranged from 5.4 to 6.7. The best improvement in sulfate levels occurred in the straw/cattle manure treatment. (C) 1997 IAWQ. Published by Elsevier Science Ltd.

The occurrence of cancer in a cohort of New South Wales coal miners

To describe the incidence of cancer in coal miners in New South Wales (NSW) between 1973 and 1992, an inception cohort of all male coal industry employees who entered the industry between 1 January 1973 and 31 December 1992 was constructed from the medical examination records of the Joint Coal Board. This cohort was matched with the NSW State Cancer Registry to determine the occurrence and type of cancer. In the cohort of 23 630 men, 297 developed 301 primary cancers in the 20-year period of observation. The standardised incidence ratio (SLR) for all cancers was 0.82. Stomach cancer has been reported to be common in coal miners but the SIR for stomach cancer was not higher than average in this cohort. A cluster of non-Hodgkin's lymphoma has been reported in a NSW coal mine but an increased risk of this cancer was not evident in the industry as a whole. Similarly a cluster of cases of brain tumour has been reported. In this cohort, the SIR for brain tumour was 1.05 (95 per cent confidence interval (CI) 0.57 to 1.76) and a risk for brain tumour remains unconfirmed. The SIR for malignant melanoma was 1.13 (CI 0.90 to 1.39) altogether and 2.02 (CI 1.31 to 2.98) for those workers who started in an open-cut mine. Overall, there does not appear to be a general risk of cancer in the NSW coal industry. Open-cut miners have an increased risk of malignant melanoma, which may be related to their exposure to the sun at work.

Evaluation of molar and incisor bite force in indigenous compared with white population in Brazil

The purpose of this study was to deter-mine maximum bite force in molar and incisor regions in young Brazilian indigenous individuals, who have had a natural diet since birth, and compare the sample with white Brazilian individuals. To do this, individuals were paired one-to-one (same weight, height, and Class I facial pattern). A secondary purpose was to elucidate the relation between bite force and gender in both populations. Eighty-two Brazilians took part in this study. Participants were aged between 18 and 28 years and were divided into two groups: 41 Xingu indigenous individuals and 41 white Brazilian individuals, with 28 men and 13 women in each group. The inclusion criteria were: having complete dentition; normal occlusion; no neurological, psychiatric or movement disorders.; no reports of toothaches; having satisfactory periodontal health; absence of large facial skeletal alterations (typical Class II and Class III individuals); and no previous treatments using occlusal splints. To measure maximum bite force, a digital dynamometer model IDDK (Kratos-Equipamentos Industriais Ltda, Cotia, Sao Paulo, Brazil) was used, with a capacity of 1000 N, adapted for oral conditions. Assessments were made in the first molar (right and left) and central incisive regions. Results reveal that mean maximum bite forces in indigenous individuals of the right molar is 421 N, left molar 429 N and incisor region is 194 14 and for white individuals of the right molar is 410 N, left molar 422 N and incisor region is 117 N. Comparing indigenous with white individuals, maximal bite force showed a tendency of being greater in the indigenous group. It was observed that the incisor region showed statistical significance (p < 0.0005) but no significance was observed in the molar region. Moreover, indigenous men showed the highest bite force values. (C) 2007 Elsevier Ltd. All rights reserved.

Critical review of acid in situ leach uranium mining: 2. Soviet Block and Asia

The technique of in situ leach (ISL) uranium mining is well established in the USA, as well as being used extensively in Eastern Europe and the former Soviet Union. The method is being proposed and tested on uranium deposits in Australia, with sulphuric acid chemistry and no restoration of groundwater following mining. ISL mines in the former Soviet Union generally used acid reagents and were operated without due consideration given to environmental protection. At many former mine sites, the extent of groundwater contamination is significant because of high salinity, heavy metal and radionuclide concentrations compared with pre-mining and changes in the hydrogeological regime caused by mining. After the political collapse of the Soviet Union by the early 1990s, most uranium mines were shut down or ordered to be phased out by government policy. Programmes of restoration are now being undertaken but are proving technically difficult and hampered by a lack of adequate financial resources. The history and problems of acid ISL sites in countries of the former Soviet Union and Asia are presented in this study.

The effect of coal particle size on colorimetric analysis of roadway dust

Colorimetric analysis of roadway dust is currently a method for monitoring the incombustible content of mine roadways within Australian underground coal mines. To test the accuracy of this method, and to eliminate errors of judgement introduced by human operators in the analysis procedure, a number of samples were tested using scanning software to determine absolute greyscale values. High variability and unpredictability of results was noted during this testing, indicating that colorimetric testing is sensitive to parameters within the mine that are not currently reproduced in the preparation of reference samples. This was linked to the dependence of colour on particle surface area, and hence also to the size distribution of coal particles within the mine environment. (C) 2001 Elsevier Science Ltd. All rights reserved.

A multi-purpose rainfall simulator for field infiltration and erosion studies

This paper describes a rainfall simulator developed for field and laboratory studies that gives great flexibility in plot size covered, that is highly portable and able to be used on steep slopes, and that is economical in its water use. The simulator uses Veejet 80100 nozzles mounted on a manifold, with the nozzles controlled to sweep to and from across a plot width of 1.5 m. Effective rainfall intensity is controlled by the frequency with which the nozzles sweep. Spatial uniformity of rainfall on the plots is high, with coefficients of variation (CV) on the body of the plot being 8-10%. Use of the simulator for erosion and infiltration measurements is discussed.

The design of hazard risk assessment matrices for ranking occupational health risks and their application in mining and minerals processing

Two hazard risk assessment matrices for the ranking of occupational health risks are described. The qualitative matrix uses qualitative measures of probability and consequence to determine risk assessment codes for hazard-disease combinations. A walk-through survey of an underground metalliferous mine and concentrator is used to demonstrate how the qualitative matrix can be applied to determine priorities for the control of occupational health hazards. The semi-quantitative matrix uses attributable risk as a quantitative measure of probability and uses qualitative measures of consequence. A practical application of this matrix is the determination of occupational health priorities using existing epidemiological studies. Calculated attributable risks from epidemiological studies of hazard-disease combinations in mining and minerals processing are used as examples. These historic response data do not reflect the risks associated with current exposures. A method using current exposure data, known exposure-response relationships and the semi-quantitative matrix is proposed for more accurate and current risk rankings.

Quantifying stresses and support requirements in the undercut and production level drifts of block and panel caving mines

A numerical modelling strategy has been developed in order to quantify the magnitude of induced stresses at the boundaries of production level and undercut level drifts for various in situ stress environments and undercut scenarios. The results of the stress modelling were in line with qualitative experiential guidelines and a limited number of induced stress measurements documented from caving sites. A number of stress charts were developed which quantify the maximum boundary stresses in drift roofs for varying in situ stress regimes, depths and undercut scenarios. This enabled many of the experiential guidelines to be quantified and bounded. A limited number of case histories of support and support performance in cave mine drifts were compared to support recommendations using the NGI classification system, The stress charts were used to estimate the Stress Reduction Factor for this system. The back-analyses suggested that the NGI classification system might be able to give preliminary estimates of support requirements in caving mines with modifications relating to rock bolt length and the support of production level intersections. (C) 2002 Elsevier Science Ltd. All rights reserved.

Tree use, diet and home range of the koala (Phascolarctos cinereus) at Blair Athol, central Queensland

Free-ranging koalas (Phascolarctos cinereus) were monitored by means of radio-relocation in the area of Blair Athol Coal Mine and surrounding properties. Daytime tree use, home range and diet of these koalas was determined in spring and autumn, as was the leaf moisture composition of potential fodder species. Koalas used on average 93 (male koalas) and 56 (female koalas) trees during the period of observation, occupying home ranges of 135 and 101 ha respectively. Mean sightings per tree were 1.19 for both males and females and home-range sizes were not significantly different between sexes or seasons. Koalas were observed returning to previously used daytime roosting trees infrequently (

New arsenite-oxidizing bacteria isolated from Australian gold mining environments - Phylogenetic relationships

Nine novel arsenite-oxidizing bacteria have been isolated from two different gold mine environments in Australia. Four of these organisms grow chemolithoautotrophically with oxygen as the terminal electron acceptor, arsenite as the electron donor, and carbon dioxide-bicarbonate as the sole carbon source. Five heterotrophic arsenite-oxidizing bacteria were also isolated, one of which was found to be both phylogenetically and physiologically identical to the previously described heterotrophic arsenite oxidizer misidentified as Alcaligenes faecalis. The results showed that this strain belongs to the genus Achromobacter. Phylogenetically, the arsenite-oxidizing bacteria fall within two separate subdivisions of the Proteobacteria. Interestingly, the chemolithoautotrophic arsenite oxidizers belong to the alpha-Proteobacteria, whereas the heterotrophic arsenite oxidizers belong to the beta-Proteobacteria.