Comparison of DEM and experiment for a scale model SAG mill

Predictions of flow patterns in a 600-mm scale model SAG mill made using four classes of discrete element method (DEM) models are compared to experimental photographs. The accuracy of the various models is assessed using quantitative data on shoulder, toe and vortex center positions taken from ensembles of both experimental and simulation results. These detailed comparisons reveal the strengths and weaknesses of the various models for simulating mills and allow the effect of different modelling assumptions to be quantitatively evaluated. In particular, very close agreement is demonstrated between the full 3D model (including the end wall effects) and the experiments. It is also demonstrated that the traditional two-dimensional circular particle DEM model under-predicts the shoulder, toe and vortex center positions and the power draw by around 10 degrees. The effect of particle shape and the dimensionality of the model are also assessed, with particle shape predominantly affecting the shoulder position while the dimensionality of the model affects mainly the toe position. Crown Copyright (C) 2003 Published by Elsevier Science B.V. All rights reserved.

Critical comparison of Julius Kruttschnitt Mineral Research Centre (JKMRC) blast fragmentation models

Blast fragmentation can have a significant impact on the profitability of a mine. An optimum run of mine (ROM) size distribution is required to maximise the performance of downstream processes. If this fragmentation size distribution can be modelled and controlled, the operation will have made a significant advancement towards improving its performance. Blast fragmentation modelling is an important step in Mine to Mill™ optimisation. It allows the estimation of blast fragmentation distributions for a number of different rock mass, blast geometry, and explosive parameters. These distributions can then be modelled in downstream mining and milling processes to determine the optimum blast design. When a blast hole is detonated rock breakage occurs in two different stress regions - compressive and tensile. In the-first region, compressive stress waves form a 'crushed zone' directly adjacent to the blast hole. The second region, termed the 'cracked zone', occurs outside the crush one. The widely used Kuz-Ram model does not recognise these two blast regions. In the Kuz-Ram model the mean fragment size from the blast is approximated and is then used to estimate the remaining size distribution. Experience has shown that this model predicts the coarse end reasonably accurately, but it can significantly underestimate the amount of fines generated. As part of the Australian Mineral Industries Research Association (AMIRA) P483A Mine to Mill™ project, the Two-Component Model (TCM) and Crush Zone Model (CZM), developed by the Julius Kruttschnitt Mineral Research Centre (JKMRC), were compared and evaluated to measured ROM fragmentation distributions. An important criteria for this comparison was the variation of model results from measured ROM in the-fine to intermediate section (1-100 mm) of the fragmentation curve. This region of the distribution is important for Mine to Mill™ optimisation. The comparison of modelled and Split ROM fragmentation distributions has been conducted in harder ores (UCS greater than 80 MPa). Further work involves modelling softer ores. The comparisons will be continued with future site surveys to increase confidence in the comparison of the CZM and TCM to Split results. Stochastic fragmentation modelling will then be conducted to take into account variation of input parameters. A window of possible fragmentation distributions can be compared to those obtained by Split . Following this work, an improved fragmentation model will be developed in response to these findings.

Preliminary comparison of three lightcycler pcr assays for the detection of herpes simplex virus in swab specimens

Three Herpes Simplex Virus LightCycler polymerase chain reaction assays were compared for the detection of herpes simplex virus in 48 swab specimens. The assays comprised of one in-house assay and two commercial kits: the Artus HSV LC RealArt PCR kit and the Roche LightCycler HSV 1/2 Detection kit. On the whole, the three assays had comparable sensitivities. However, differentiation of herpes simplex virus types 1 and 2 by melting curve analysis was problematic in all assays. Overall, the results highlight the limitations of typing herpes simplex virus by melting curve analysis.

Accuracy of Mothers' Retrospective Reports of Smoking During Pregnancy: Comparison with Twin Sister Informant Ratings

Retrospective assessment of maternal smoking or substance use during pregnancy is sometimes unavoidable. The unusually close relationship of twin sister pairs permits comparison of self-report data versus co-twin informant data on substance use during pregnancy. Information about smoking during pregnancy has been gathered from a series of mothers from an Australian volunteer twin panel (576 women reporting on 995 pregnancies), supplemented in many cases by independent ratings of their smoking by twin sister informants (821 pregnancies). Estimates of the proportion of women who had never smoked regularly (56-58%), who had smoked but did not smoke during a particular pregnancy (16-21%), or who smoked throughout the pregnancy (16-18%), were in good agreement whether based on self-report or twin sister informant data. However, informants underreported cases who smoked during the first trimester but then quit (1-3% versus 7-9% by self-report). Women who smoked throughout pregnancy (by informant report) rarely denied a history of regular smoking (

Exact results for a tunnel-coupled pair of trapped Bose-Einstein condensates

A model describing coherent quantum tunnelling between two trapped Bose-Einstein condensates is discussed. It is not well known that the model admits an exact solution, obtained some time ago, with the energy spectrum derived through the algebraic Bethe ansatz. An asymptotic analysis of the Bethe ansatz equations leads us to explicit expressions for the energies of the ground and the first excited states in the limit of weak tunnelling and all energies for strong tunnelling. The results are used to extract the asymptotic limits of the quantum fluctuations of the boson number difference between the two Bose-Einstein condensates and to characterize the degree of coherence in the system.

Estimation of body fatness from body mass index and bioelectrical impedance: comparison of New Zealand European, Maori and Pacific Island children

Objective: To compare percentage body fat (%BF) for a given body mass index (BMI) among New Zealand European, Maori and Pacific Island children. To develop prediction equations based on bioimpedance measurements for the estimation of fat-free mass (FFM) appropriate to children in these three ethnic groups. Design: Cross-sectional study. Purposive sampling of schoolchildren aimed at recruiting three children of each sex and ethnicity for each year of age. Double cross-validation of FFM prediction equations developed by multiple regression. Setting: Local schools in Auckland. Subjects: Healthy European, Maori and Pacific Island children (n = 172, 83 M, 89 F, mean age 9.4 +/- 2.8(s. d.), range 5 - 14 y). Measurements: Height, weight, age, sex and ethnicity were recorded. FFM was derived from measurements of total body water by deuterium dilution and resistance and reactance were measured by bioimpedance analysis. Results: For fixed BMI, the Maori and Pacific Island girls averaged 3.7% lower % BF than European girls. For boys a similar relation was not found since BMI did not significantly influence % BF of European boys ( P = 0.18). Based on bioimpedance measurements a single prediction equation was developed for all children: FFM (kg) = 0.622 height (cm)(2)/ resistance +0.234 weight (kg)+1.166, R-2 = 0.96, s. e. e. = 2.44 kg. Ethnicity, age and sex were not significant predictors. Conclusions: A robust equation for estimation of FFM in New Zealand European, Maori and Pacific Island children in the 5 - 14 y age range that is more suitable than BMI for the determination of body fatness in field studies has been developed. Sponsorship: Maurice and Phyllis Paykel Trust, Auckland University of Technology Contestable Grants Fund and the Ministry of Health.

The egalitarian leader: A comparison of leadership in Australia and New Zealand

This article compares leadership in Australia and New Zealand based on data collected as a part of the GLOBE (Global Leadership and Organizational Behavior effectiveness) 62-nation culture and leadership project. Exploratory and confirmatory factor analyses were used to demonstrate that etic (universal) dimensions of 'Charismatic' and 'Self-Protective' leadership are evident in both cultures, but that the dimensions have emic (local) culturally determined manifestations. These emic manifestations were stronger in New Zealand than in Australia. Leadership effectiveness incorporated the negative emic dimension of 'Bureaucratic' leadership (both countries), and the positive emic dimension of 'Egalitarian leadership' in Australia and 'Team leadership' in New Zealand. Both models of leadership nonetheless represent styles of leadership based on egalitarian principles.

A comparison of model laws as a starting point for the development of an enforceable international consumer protection regime

This article is concerned primarily with an examination and comparison of select aspects of the model international consumer protection laws proposed by the United Nations (UN), the European Union (EU), and the Organisation for Economic Co-operation and Development (OECD), using the Trade Practices Act 1974 (Australia) as a basis for examination and comparison. As a secondary consideration, it also broadly examines the content of, and differences between, the model laws. The motive for this article is that any future enforceable international consumer protection regime (possibly in the form of an international treaty or convention) would need to take into account the UN, EU and OECD guidelines. A cross-comparison of those model laws, and a comparison of them with the consumer protection provisions of a well established national consumer protection law, should provide a useful starting point for the development of such a regime. The 'select aspects' of the model laws in question are the various provisions of those laws which could relate to situations involving the wrong delivery or non-delivery of goods.

A comparison of two methods for the calculation of accumulated oxygen deficit

The aim of this study was to compare accumulated oxygen deficit data derived using two different exercise protocols with the aim of producing a less time-consuming test specifically for use with athletes. Six road and four track male endurance cyclists performed two series of cycle ergometer tests. The first series involved five 10 min sub-maximal cycle exercise bouts, a (V) over dotO(2peak) test and a 115% (V) over dotO(2peak) test. Data from these tests were used to estimate the accumulated oxygen deficit according to the calculations of Medbo et al. (1988). In the second series of tests, participants performed a 15 min incremental cycle ergometer test followed, 2 min later, by a 2 min variable resistance test in which they completed as much work as possible while pedalling at a constant rate. Analysis revealed that the accumulated oxygen deficit calculated from the first series of tests was higher (P< 0.02) than that calculated from the second series: 52.3 +/- 11.7 and 43.9 +/- 6.4 ml . kg(-1), respectively (mean +/- s). Other significant differences between the two protocols were observed for (V) over dot O-2peak, total work and maximal heart rate; all were higher during the modified protocol (P

A comparison of the cycling performance of cyclists and triathletes

The aim of this study was to compare the cycling performance of cyclists and triathletes. Each week for 3 weeks, and on different days, 25 highly trained male cyclists and 18 highly trained male triathletes performed: (1) an incremental exercise test on a cycle ergometer for the determination of peak oxygen consumption ((V) over dot O-2peak), peak power output and the first and second ventilatory thresholds, followed 15 min later by a sprint to volitional fatigue at 150% of peak power output; (2) a cycle to exhaustion test at the (V) over dot O-2peak power output; and (3) a 40-km cycle time-trial. There were no differences in (V) over dot O-2peak, peak power output, time to volitional fatigue at 150% of peak power output or time to exhaustion at (V) over dot O-2peak power output between the two groups. However, the cyclists had a significantly faster time to complete the 40-km time-trial (56:18 +/- 2:31 min:s; mean +/- s) than the triathletes (58:57 +/- 3:06 min:s; P < 0.01), which could be partially explained (r = 0.34-0.51; P < 0.05) by a significantly higher first (3.32 +/- 0.36 vs 3.08 +/- 0.36 l . min(-1)) and second ventilatory threshold (4.05 +/- 0.36 vs 3.81 +/- 0.29 l . min(-1); both P < 0.05) in the cyclists compared with the triathletes. In conclusion, cyclists may be able to perform better than triathletes in cycling time-trial events because they have higher first and second ventilatory thresholds.

Identification and comparison of aerobic and denitrifying polyphosphate-accumulating organisms

Two laboratory-scale sequencing batch reactors (SBRs) were operated for enhanced biological phosphorus removal (EBPR) in alternating anaerobic-aerobic or alternating anaerobic-anoxic modes, respectively. Polyphosphate-accumulating organisms (PAOs) were enriched in the anaerobic-aerobic SBR and denitrifying PAOs (DPAOs) were enriched in the anaerobic-aerobic SBR. Fluorescence in situ hybridization (FISH) demonstrated that the well-known PAO, Candidatus Accumulibacter phosphatis was abundant in both SBRs, and post-FISH chemical staining with 4,6-diamidino-2-phenylindol (DAPI) confirmed that they accumulated polyphosphate. When the anaerobic-anoxic SBR enriched for DPAOs was converted to anaerobic-aerobic operation, aerobic uptake of phosphorus by the resident microbial community occurred immediately. However, when the anaerobic-aerobic SBR enriched for PAOs was exposed to one cycle with anoxic rather than aerobic conditions, a 5-h lag period elapsed before phosphorus uptake proceeded. This anoxic phosphorus-uptake lag phase was not observed in the subsequent anaerobic-aerobic cycle. These results demonstrate that the PAOs that dominated the anaerobic-aerobic SBR biomass were the same organisms as the DPAOs enriched under anaerobic-anoxic conditions. (C) 2003 Wiley Periodicals, Inc.

Quality of life assessment in the community-dwelling elderly: Validation of the Assessment of Quality of Life (AQoL) Instrument and comparison with the SF-36

Measurement of Health-Related Quality of Life (HRQoL) of the elderly requires instruments with demonstrated sensitivity, reliability, and validity, particularly with the increasing proportion of older people entering the health care system. This article reports the psychometric properties of the 12-item Assessment of Quality of Life (AQoL) instrument in chronically ill community-dwelling elderly people with an 18-month follow-up. Comparator instruments included the SF-36 and the OARS. Construct validity of the AQoL was strong when examined via factor analysis and convergent and divergent validity against other scales. Receiver Operator Characteristic (ROC) curve analyses and relative efficiency estimates indicated the AQoL is sensitive, responsive, and had the strongest predicative validity for nursing home entry. It was also sensitive to economic prediction over the follow-up. Given these robust psychometric properties and the brevity of the scale, AQoL appears to be a suitable instrument for epidemiologic studies where HRQoL and utility data are required from elderly populations. (C) 2003 Elsevier Science Inc. All rights reserved.

Comparison of the in vitro neuromuscular activity of venom from three Australian snakes (Hoplocephalus stephensi, Austrelaps superbus and Notechis scutatus): Efficacy of tiger snake antivenom

1. Tiger snake antivenom, raised against Notechis scutatus venom, is indicated not only for the treatment of envenomation by this snake, but also that of the copperhead (Austrelaps superbus ) and Stephen's banded snake (Hoplocephalus stephensi ). The present study compared the neuromuscular pharmacology of venom from these snakes and the in vitro efficacy of tiger snake antivenom. 2. In chick biventer cervicis muscle and mouse phrenic nerve diaphragm preparations, all venoms (3-10 mug/mL) produced inhibition of indirect twitches. In the biventer muscle, venoms (10 mug/mL) inhibited responses to acetylcholine (1 mmol/L) and carbachol (20 mumol/L), but not KCl (40 mmol/L). The prior (10 min) administration of 1 unit/mL antivenom markedly attenuated the neurotoxic effects of A. superbus and N. scutatus venoms (10 mug/mL), but was less effective against H. stephensi venom (10 mug/mL); 5 units/mL antivenom attenuated the neurotoxic activity of all venoms. 3. Administration of 5 units/mL antivenom at t(90) partially reversed, over a period of 3 h, the inhibition of twitches produced by N. scutatus (10 mug/mL; 41% recovery), A. superbus (10 mug/mL; 25% recovery) and H. stephensi (10 mug/mL; 50% recovery) venoms. All venoms (10-100 mug/mL) also displayed signs of in vitro myotoxicity. 4. The results of the present study indicate that all three venoms contain neurotoxic activity that is effectively attenuated by tiger snake antivenom.

Abnormalities of the PTH-vitamin D axis and bone turnover markers in children, adolescents and adults with cystic fibrosis: comparison with healthy controls

Abnormalities of calcium and vitamin D metabolism in cystic fibrosis (CF) are well documented. We tested the hypothesis that alterations in calcium metabolism are related to vitamin D deficiency, and that bone resorption is increased relative to accretion in patients with CF. Calcitropic hormones, electrolytes, osteocalcin (OC) and bone alkaline phosphatase (BAP), (markers of bone mineralisation), urinary deoxypyridinoline [total (t) Dpd, a marker of bone resorption] and lumbar spine bone mineral density (LS BMD), expressed as a z-score, were measured in 149 (81 M) CF and 141 (61 M) control children aged 5.3-10.99 years, adolescents aged 11-17.99 years and adults aged 18-55.9 years. Data were analysed by multiple regression to adjust for age. In patients, FEV1% predicted and CRP (as disease severity markers), genotype and pancreatic status (PS) were recorded. The distribution of PTH differed between groups (P