Effects of slurry rheology on industrial grinding performance

To determine the effect of slurry rheology on industrial grinding performance, 45 surveys were conducted on 16 full-scale grinding mills in five sites. Four operating variables - mill throughput, slurry density, slurry viscosity and feed fines content-were investigated. The rheology of the mill discharge slurries was measured either on-line or off-line, and the data were processed using a standard procedure to obtain a full range of flow curves. Multi-linear regression was employed as a statistical analysis tool to determine whether or not rheological effects exert an influence on industrial grinding, and to assess the influence of the four mill operating conditions on mill performance in terms of the Grinding Index, a criterion describing the overall breakage of particles across the mill. The results show that slurry rheology does influence industrial grinding. The trends of these effects on Grinding Index depend upon the rheological nature of the slurry-whether the slurries are dilatant or pseudoplastic, and whether they exhibit a high or low yield stress. The interpretation of the regression results is discussed, the observed effects are summarised, and the potential for incorporating rheological principles into process control is considered, Guidelines are established to improve industrial grinding operations based on knowledge of the rheological effects. This study confirms some trends in the effect of slurry rheology on grinding reported in the literature, and extends these to a broader understanding of the relationship between slurry properties and rheology, and their effects on industrial milling performance. (C) 2002 Elsevier Science B.V. All rights reserved.

Effect of aestivation on muscle characteristics and locomotor performance in the Green-striped burrowing frog, Cyclorana alboguttata

The Green-striped burrowing frog. Cyclorana alboguttata survives extended drought periods by burrowing underground and aestivating. These frogs remain immobile within cocoons of shed skin and Mucus during aestivation and emerge from their burrows upon heavy rains to feed and reproduce. Extended periods of immobilisation in mammals typically result in muscle atrophy and a decrease in muscle performance. We examined the effect of aestivation and hence prolonged immobilisation, on skeletal Muscle mass. in vitro muscle performance, and locomotor performance in C. alboguttata. Frogs were aestivated in soil for 3 months and were compared with control animals that remained active, were fed, and had a continual supply of water. Compared to the controls, the wet mass of the gastrocnemius. sartorius, gracilus major. semimembranosus. peroneus, extensor cruris, tibialis posticus and tibialis anticus longus of aestivators remained unchanged indicating no muscle atrophy. The in-vitro performance characteristics of the gastroenemius muscle were maintained and burst swimming speed Was Unaffected, requiring no recovery from the extended period of immobilisation associated with aestivation. This preservation of muscle size, contractile condition and locomotor performance through aestivation enables C. alboguttata to compress their life history into unpredictable windows of opportunity, whenever heavy rains occur.

Investigation of the effects of chrome ball charge on slurry rheology and milling performance

Ten surveys of the ball milling circuit at the Mt Isa Mines (MIM) Copper Concentrator were conducted aiming to identify any changes in slurry theology caused by the use of chrome balls charge, and the associated effect on grinding performance. Slurry theology was measured using an on-line viscometer. The data were mass balanced and analysed with statistical tools. Comparison of the rheogram demonstrated that slurry density and fines content affected slurry rheology significantly, while the effect of the chrome ball charge being negligible. Statistical analysis showed the effects of mill throughput and cyclone efficiency on the Grinding Index (a term describing the overall breakage). There was no difference in the Grinding Index between using the chrome ball charge and the ordinary steel ball charge. (C) 2002 Elsevier Science Ltd. All rights reserved.

High-performance L-band series and parallel switches using low-cost p-i-n diodes

Low-cost UHF-band p-i-n diodes are used to develop high-performance L-band series and parallel switches. To stop the rectification of large RF, signals, the diodes are biased at a large reverse-bias voltage. Parasitic elements of the diodes are tuned out using LC circuits in biasing circuits without increasing the size of the switches. (C) 2002 John Wiley Sons, Inc.

Performance measurement in child protection

The increasing use of performance measurement by government means that child protection services are under pressure to demonstrate effectiveness in protecting children from harm and efficiency in the use of public funds to help children and families. From a policy perspective, the way performance measurement is conceptualised and implemented can have major consequences for service delivery. This paper examines key issues raised in the literature about performance measurement, the context for its introduction in child protection, how the concepts of effectiveness and efficiency are dealt with, how client outcomes are defined, and assumptions about 'good performance'. An overview of performance measurement in child protection in Australia is provided. The paper argues that a critical approach to performance measurement in child protection can contribute to improved service delivery to clients.

Pro re nata medication for psychoses: an audit of practice in two metropolitan hospitals

Objective: To examine the use of pro re nata (PRN) (as needed) medication in hospitalized patients with psychotic disorders. Methods: Retrospective chart reviews were conducted at two large public psychiatry units situated in inner city general hospitals. Pro re nata medication prescription, administration and outcomes were examined during inpatient episodes of care for 184 consecutive admissions of patients diagnosed with a psychotic disorder. Patient demographics, diagnoses, and regularly prescribed medication were also recorded. All admissions were drawn from a three-month period from December 1998-February 1999. Results: The most prevalent diagnoses were schizophrenia related disorders (n = 111) and mania (n = 34). Substance use disorders (n = 49) were the most common comorbid dis-orders. Pro re nata medication was administered during the acute phase of 82% of admissions. Drugs prescribed Pro re nata were mostly typical antipsychotics, benzodiazepines and/or anti-cholinergics. Coprescription of typical antipsychotics PRN with regularly scheduled atypical antipsychotics was common (64%). Pro re nata medications accounted for 31% of the total antipsychotic dose and 28% of the total anxiolytic dose administered during acute treatment. Higher daily doses of PRN medication were given to manic patients, males, younger patients and those with substance use disorders. Pro re nata prescriptions usually specified a maximum daily dose (87%) but rarely gave indications for use (6%). Adminis-tration records frequently lacked a specified reason for use (48%) or a notation of outcome (64%). Unit staff noted medication-related morbidity in 37% of patients receiving PRN medication, compared to 3% of patients receiving only regularly scheduled medication. Extrapyramidal symptoms (EPS) were most frequently associated with administration of PRN haloperidol (Relative Risk vs other PRN medications = 5.61, 95% CI = 2.36-13.73). Conclusions: Pro re nata medications comprised a significant part of the treatment which psychotic patients received. The common practice of coprescribing PRN typical antipsychotics with scheduled atypical antipsychotics is potentially problematical since administration of PRN medication is associated with significant medication related morbidity. Preferential use of benzodiazepines as PRN agents may minimize this morbidity and foster subsequent compliance with regularly prescribed antipsychotics.

Skeletal muscle mitochondrial ATP production rate and walking performance in peripheral arterial disease

This study tested the hypotheses that skeletal muscle mitochondrial ATP production rate (MAPR) is impaired in patients with peripheral arterial disease (PAD) and that it relates positively to their walking performances. Seven untrained patients, eight exercise-trained patients and 11 healthy controls completed a maximal walking test and had muscle sampled from the gastrocnemius medialis muscle. Muscle was analysed for its MAPR in the presence of pyruvate, palmitoyl-L-carnitine or both, as well as citrate synthase (CS) activity. MAPRs were not different between untrained PAD and controls. In contrast, MAPRs (pyruvate) were significantly higher in trained PAD vs. controls. MAPR (pyruvate combinations) was also significantly higher in trained than untrained PAD muscle. MAPR and CS activity were highly correlated with walking performance in patients, but not in controls. These data do not support the hypothesis that isolated mitochondria are functionally impaired in PAD and demonstrate that the muscle mitochondrial capacity to oxidize carbohydrate is positively related to walking performance in these patients.

Standardised audit of hip fractures in Europe

The objectives of this study were to evaluate the outcomes of our patients admitted with hip fractures, and to benchmark these results with other hospitals, initially in Europe and subsequently in Australia. The Standardised Audit of Hip Fractures in Europe (SAHFE) questionnaires was used as the data gathering instrument. The participants were all patients admitted to Redcliffe Hospital with a fractured neck of femur prior to surgery. This paper reports the results of the first 70 consecutive patients admitted to Redcliffe Hospital with a fractured neck of femur from November 1st 2000. The main outcome measures were mobility, independence, residence prior to fracture; type of fracture and surgical repair; and time to surgery, survival rates and discharge destination. Results: 43 patients were admitted from home, but only 13 returned home directly from the orthopaedic ward. It is hoped that most of the 26 transferred to the rehabilitation ward will ultimately return home. 7 patients died, these were aged 82 to 102, and all had premorbid disease. Delays in surgery were apparent for 13 patients, mainly due to administrative problems. Conclusions: We support the recommendation in the Fifteenth Scottish Intercollegiate Guidelines Network Publication on the management of hip fractures, that all units treating this condition should enter an audit to evaluate their management. (author abstract)

Impact of leadership style and emotions on subordinate performance

This article examines whether the emotions of frustration and optimism mediate, fully or partially, the relationship between leadership style and subordinate performance in the context of structural equation modeling. The findings show that transformational leadership has a significant direct influence on frustration and optimism, with the negative influence of frustration having a stronger effect on performance than the positive influence of optimism. Frustration and optimism are found to have a direct influence on performance, and the emotions, frustration and optimism, fully mediate the relationship between transformational leadership and performance. Thus, the effect of transformational leadership style on performance is significant, but indirect. (C) 2002 Elsevier Science Inc. All rights reserved.

Debiasing the outcome effect: The role of instructions in an audit litigation setting

The outcome effect occurs where an evaluator, who has knowledge of the outcome of a judge's decision , assesses the quality of the judgment of that decision maker. If the evaluator has knowledge of a negative outcome, then that knowledge negatively influences his or her assessment of the ex ante judgment. For instance, jurors in a lawsuit brought against an auditor for alleged negligence are informed of an undetected fraud, even though an unqualified opinion was issued. This paper reports the results of an experiment in an applied audit judgment setting that examined methods of mitigating the outcome effect by means of instructions. The results showed that simply instructing or warning the evaluator about the potential biasing effects of outcome information was only weakly effective. However, instructions that stressed either (1) the cognitive non-normativeness of the outcome effect or (2) the seriousness and gravity of the evaluation ameliorated the effect significantly. From a theoretical perspective, the results suggest that there may both motivational and cognitive components to the outcome effect. In all, the findings suggest awareness of the outcome effect and use of relatively nonintrusive instructions to evaluators may effectively counteract the potential for the outcome bias.

Simulation of Oxford University Gun Tunnel performance using a quasi-one-dimensional model

The performance of the Oxford University Gun Tunnel has been estimated using a quasi-one-dimensional simulation of the facility gas dynamics. The modelling of the actual facility area variations so as to adequately simulate both shock reflection and flow discharge processes has been considered in some detail. Test gas stagnation pressure and temperature histories are compared with measurements at two different operating conditions - one with nitrogen and the other with carbon dioxide as the test gas. It is demonstrated that both the simulated pressures and temperatures are typically within 3% of the experimental measurements.

Quantification and stability of everolimus (SDZ RAD) in human blood by high-performance liquid chromatography-electrospray tandem mass spectrometry

We report here a validated method for the quantification of a new immunosuppressant drug, everolimus (SDZ RAD), using HPLC-tandem mass spectrometry. Whole blood samples (500 mul) were prepared by protein precipitation, followed by C-18 solid-phase extraction. Mass spectrometric detection was by selected reaction monitoring with an electrospray interface operating in positive ionization mode. The assay was linear from 0.5 to 100 mug/l (r(2) > 0.996, n = 9). The analytical recovery and inter-day imprecision, determined using whole blood quality control samples (n = 5) at 0.5, 1.2, 20.0, and 75.0 mug/l, was 100.3-105.4% and less than or equal to7.6%, respectively. The assay had a mean relative recovery of 94.8 +/- 3.8%. Extracted samples were stable for up to 24 h. Fortified everolimus blood samples were stable at -80 degreesC for at least 8 months and everolimus was found to be stable in blood when taken through at least three freeze-thaw cycles. The reported method provides accurate, precise and specific measurement of everolimus in blood over a wide analytical range and is currently supporting phase 11 and III clinical trials. (C) 2002 Elsevier Science B.V. All rights reserved.

Effect of the movement speed of resistance training exercises on sprint and strength performance in concurrently training elite junior sprinters

The aim of this study was to determine the effects of 7 weeks of high- and low-velocity resistance training on strength and sprint running performance in nine male elite junior sprint runners (age 19.0 +/- 1.4 years, best 100 m times 10.89 +/- 0.21 s; mean +/- s). The athletes continued their sprint training throughout the study, but their resistance training programme was replaced by one in which the movement velocities of hip extension and flexion, knee extension and flexion and squat exercises varied according to the loads lifted (i.e. 30-50% and 70-90% of 1-RM in the high- and low-velocity training groups, respectively). There were no between-group differences in hip flexion or extension torque produced at 1.05, 4.74 or 8.42 rad . s(-1), 20 m acceleration or 20 m 'flying' running times, or 1-RM squat lift strength either before or after training. This was despite significant improvements in 20 m acceleration time (P < 0.01), squat strength (P< 0.05), isokinetic hip flexion torque at 4.74 rad . s(-1) and hip extension torque at 1.05 and 4.74 rad . s(-1) for the athletes as a whole over the training period. Although velocity-specific strength adaptations have been shown to occur rapidly in untrained and non-concurrently training individuals, the present results suggest a lack of velocity-specific performance changes in elite concurrently training sprint runners performing a combination of traditional and semi-specific resistance training exercises.

Effect of periparturient diseases accompanied by excessive vulval discharge and weaning to mating interval on sow reproductive performance

Objective To evaluate the effect of periparturient disease accompanied by vulval discharge, and weaning-to-mating intervals, on sow fertility and litter size. Design Reproductive data were collected and analysed from 19 Hungarian swine herds over a 4 year period. Conception rates, farrowing rates and litter sizes of sows with periparturient disease accompanied by vulval discharge were used to evaluate the relationship between duration of vulval discharge and subsequent fertility and litter size. The possibility of interactions between weaning-to-mating intervals and duration of vulval discharges was investigated to determine if there was any effect on subsequent fertility and litter size. Results and conclusions Both parity 1 and parity 2 to 8 sows having had periparturient disease accompanied by vulval discharge in excess of 6 days duration had significantly (P < 0.001) lower subsequent fertility (conception, farrowing and adjusted farrowing rates) compared with sows of similar parity where the duration of vulval discharge was < 4 or 4 to 6 days. There was no difference in fertility rates between sows, in both parity categories, with vulval discharge for < 4 days compared with 4 to 6 days. A duration of vulval discharge in excess of 6 days in parity 1 sows significantly reduced litter size (total born and live-born) in subsequent farrowings, but not in parity 2 to 8 sows. There was no interaction between the duration of vulval discharge and post-weaning to mating intervals. However sows with weaning to mating intervals between 7 and 10 days had smaller (P < 0.001) subsequent litter sizes compared with 3 to 6 or 11 to 14 day intervals. It was concluded that the duration of vulval discharge in excess of 6 days was an indication of a severe persistent endometritis adversely affecting fertility of sows.