HPGR model verification and scale-up

This paper summarises test results that were used to validate a model and scale-up procedure of the high pressure grinding roll (HPGR) which was developed at the JKMRC by Morrell et al. [Morrell, Lim, Tondo, David,1996. Modelling the high pressure grinding rolls. In: Mining Technology Conference, pp. 169-176.]. Verification of the model is based on results from four data sets that describe the performance of three industrial scale units fitted with both studded and smooth roll surfaces. The industrial units are currently in operation within the diamond mining industry and are represented by De Beers, BHP Billiton and Rio Tinto. Ore samples from the De Beers and BHP Billiton operations were sent to the JKMRC for ore characterisation and HPGR laboratory-scale tests. Rio Tinto contributed an historical data set of tests completed during a previous research project. The results conclude that the modelling of the HPGR process has matured to a point where the model may be used to evaluate new and to optimise existing comminution circuits. The model prediction of product size distribution is good and has been found to be strongly dependent of the characteristics of the material being tested. The prediction of throughput and corresponding power draw (based on throughput) is sensitive to inconsistent gap/diameter ratios observed between laboratory-scale tests and full-scale operations. (C) 2004 Elsevier Ltd. All rights reserved.

Attitude change and the public-private attitude distinction

In this paper, we highlight the importance of the distinction between public and private attitudes in research on attitude change. First, we clarify the definitions of public and private attitudes by locating the researcher as a potential source of influence. In a test of this definition, we compare participant reports of potentially embarrassing behaviour and the study's importance between participants responding when a researcher has potential access to their reports (public condition), and participants whose reports the researcher has no potential access to (private condition). Participants high in public self-focus or low in defensive self-presentation reported the study to be more important in the public condition than the private condition. Further, participants in the public condition reported less frequency of engaging in embarrassing behaviours than those in the private condition, an effect not moderated by individual differences. We conclude that the public-private distinction is an essential element in attitude change theory.

Beyond winning and losing: Guidelines for evaluating high performance coaches

This paper proposes a three-step method of evaluating high performance coaches involving feedback from the athletes. First, data are collected using an instrument such as the Coaching Behavior Scale for Sport (CBS-S: Cote, Yardley, Hay, Sedgwick, & Baker, 1999). Second, a summary report is prepared with descriptive information regarding the frequency of behaviors demonstrated by the coach that can be compared to previous results or to a criterion measure. The third step involves appropriate personnel reviewing the report and subsequently providing guidance for individual coach development. This three-step appraisal method provides useful evaluative feedback to coaches and has been used in several sport programs in Canada, the United States, and Australia.

Small-scale randomized controlled trials need more powerful methods of mediational analysis than the Baron-Kenny method

Objective: To devise more-effective physical activity interventions, the mediating mechanisms yielding behavioral change need to be identified. The Baron-Kenny method is most commonly used. but has low statistical power and May not identify mechanisms of behavioral change in small-to-medium size Studies. More powerful statistical tests are available, Study Design and Setting: Inactive adults (N = 52) were randomized to either a print or a print-plus-telephone intervention. Walking and exercise-related social support Were assessed at baseline, after file intervention, and 4 weeks later. The Baron-Kenny and three alternative methods of mediational analysis (Freedman-Schatzkin; MacKinnon et al.: bootstrap method) were used to examine the effects of social support on initial behavior change and maintenance. Results: A significant mediational effect of social support on initial behavior change was indicated by the MacKinnon et al., bootstrap. and. marginally. Freedman-Schatzkin methods, but not by the Baron-Kenny method. No significant mediational effecl of social support on maintenance of walking was found. Conclusions: Methodologically rigorous intervention studies to identify mediators of change in physical activity are costly and labor intensive, and may not be feasible with large samples. The Use of statistically powerful tests of mediational effects in small-scale studies can inform the development of more effective interventions. (C) 2006 Elsevier Inc. All rights reserved.

Workplace justice, citizenship behavior, and turnover intentions in a union context: examining the mediating role of perceived union support and union instrumentality

This study examined the relationship between workplace justice afforded by the grievance system and the union outcomes of citizenship behavior and turnover intentions and the mechanisms that underpin these relationships. Respondents (N = 187) were members of a large public sector union in Singapore. Results revealed that perceived union support and union instrumentality fully mediated the relationship between the dimensions of workplace justice and citizenship behavior directed toward the union (OCBO) and citizenship behavior directed at other union members (OCBI). Union instrumentality partially mediated the procedural justice–turnover intentions relationship.

Majority versus minority influence and prediction of behavioral intentions and behavior

Two experiments examined the effects of majority and minority influence on attitude-consistent behavioral intentions. In the first experiment, when attitudes were changed via minority influence there was a greater likelihood to engage in an attitude-consistent behavioral intention than when attitudes were changed via majority influence. This suggests that minority influence leads to stronger attitudes (based on systematic processing) that are more predictive of behavioral intentions, while attitude change via majority influence is due to compliance through non-systematic processing. Further support for this interpretation comes from the finding that the amount of message-congruent elaboration mediated behavioral intention. When there was no attitude change, there was no impact on behavioral intention to engage in an attitude-consistent behavior. Experiment 2 explored the role of personal relevance of the topic and also included a real behavioral measure. When the topic was of low personal relevance, the same pattern was found as Experiment 1. When the topic was of high personal relevance, thus increasing the motivation to engage in systematic processing, attitudes changed by both a majority and minority source increased behavioral intention and actual behavior. The results are consistent with the view that both majorities and minorities can lead to different processes and consequences under different situations. © 2006 Elsevier Inc. All rights reserved.

Blurred edges look faint, and faint edges look sharp:The effect of a gradient threshold in a multi-scale edge coding model

A multi-scale model of edge coding based on normalized Gaussian derivative filters successfully predicts perceived scale (blur) for a wide variety of edge profiles [Georgeson, M. A., May, K. A., Freeman, T. C. A., & Hesse, G. S. (in press). From filters to features: Scale-space analysis of edge and blur coding in human vision. Journal of Vision]. Our model spatially differentiates the luminance profile, half-wave rectifies the 1st derivative, and then differentiates twice more, to give the 3rd derivative of all regions with a positive gradient. This process is implemented by a set of Gaussian derivative filters with a range of scales. Peaks in the inverted normalized 3rd derivative across space and scale indicate the positions and scales of the edges. The edge contrast can be estimated from the height of the peak. The model provides a veridical estimate of the scale and contrast of edges that have a Gaussian integral profile. Therefore, since scale and contrast are independent stimulus parameters, the model predicts that the perceived value of either of these parameters should be unaffected by changes in the other. This prediction was found to be incorrect: reducing the contrast of an edge made it look sharper, and increasing its scale led to a decrease in the perceived contrast. Our model can account for these effects when the simple half-wave rectifier after the 1st derivative is replaced by a smoothed threshold function described by two parameters. For each subject, one pair of parameters provided a satisfactory fit to the data from all the experiments presented here and in the accompanying paper [May, K. A. & Georgeson, M. A. (2007). Added luminance ramp alters perceived edge blur and contrast: A critical test for derivative-based models of edge coding. Vision Research, 47, 1721-1731]. Thus, when we allow for the visual system's insensitivity to very shallow luminance gradients, our multi-scale model can be extended to edge coding over a wide range of contrasts and blurs. © 2007 Elsevier Ltd. All rights reserved.

Scale and scope economies and the efficient vertical and horizontal configuration of the water industry:a survey of the literature

This paper surveys the literature on scale and scope economies in the water and sewerage industry. The magnitude of scale and scope economies determines the cost efficient configuration of any industry. In the case of a regulated sector, reliable estimates of these economies are relevant to inform reform proposals that promote vertical (un)bundling and mergers. The empirical evidence allows some general conclusions. First, there is considerable evidence for the existence of vertical scope economies between upstream water production and distribution. Second, there is only mixed evidence on the existence of (dis)economies of scope between water and sewerage activities. Third, economies of scale exist up to certain output level, and diseconomies of scale arise if the company increases its size beyond this level. However, the optimal scale of utilities also appears to vary considerably between countries. Finally, we briefly consider the implications of our findings for water pricing and point to several directions for necessary future empirical research on the measurement of these economies, and explaining their cross country variation.

Management of nut allergy influences quality of life and anxiety in children and their mothers

Nut allergy is known to impact on the quality of life (QoL) and anxiety of both the allergic child and their parents, but little is known about how the management of food allergy is associated with these variables. To investigate the impact of nut allergy on QoL and anxiety in mothers and children with nut allergy in order to identify management strategies that may influence these factors. Forty-one nut allergic children (age 6–16 yrs) and their mothers completed questionnaires to assess maternal and children’s QoL (PedsQL™, WHOQOL-BREF, FAQL-PB), anxiety (SCAS, STAI) and perceived stress scale (PSS). Children also completed a nut allergy specific QoL questionnaire. Demographic data, details of previous reactions, test results and management plans were collected using parent-report questionnaires and hospital notes. Children with nut allergy had poorer emotional (p = 0.004), social (p = 0.043), and psychological (p = 0.006) QoL compared to healthy normative data. Maternal and child QoL and anxiety were not influenced by the severity of previous reactions. Mother and child reported lower anxiety (p = 0.043 and p < 0.001 respectively) when the child was prescribed an epinephrine auto-injector. Anxiety was not associated with whether the child carried the auto-injector or whether they strictly avoided traces of nuts in foods. Prescribing auto-injectors is associated with reduced anxiety for food allergic children and their mothers, but is not associated with improved adherence with medical management or reduced risk-taking behavior.

Maternal cognitions, psychopathologic symptoms, and infant temperament as predictors of early infant feeding problems:a longitudinal study

Objective: The current study examined the contribution of prenatal and postnatal maternal core beliefs, self-esteem, psychopathologic symptoms, and postnatal infant temperament to the prediction of infant feeding difficulties. Method: Ninety-nine women completed questionnaires assessing their core beliefs, psychopathology, and self-esteem during pregnancy and at 6 months postpartum. At 6 months, mothers also rated their infant's temperament and feeding, and were observed feeding their infants. Results: Maternal reports of child feeding difficulties were predicted by higher levels of emotional deprivation and entitlement core beliefs and lower levels of self-sacrifice and enmeshment core beliefs during pregnancy. Postnatal social isolation core beliefs, lower maternal self-esteem, and more difficult infant temperament added significantly to the variance explained by prenatal factors. Maternal core beliefs, self-esteem, psychopathology, and infant temperament failed to significantly predict independent observations of child food refusal. Conclusion: Maternal cognitions are implicated in the development of maternal reports of feeding difficulty.

Well-Behavior, Well-Posedness and Nonsmooth Analysis

AMS subject classification: 90C30, 90C33.

Understanding the cycle of violence: An examination of bully and victim social roles in early childhood

The purpose of this study was to assess the prevalence of bullying and victimization in a metropolitan area. A cross-sectional study with kindergarten (n = 127) and first grade (n = 126) children was conducted in two Miami-Dade County Public Schools and three private schools in the same area. Bullying and victimization behavior and social acceptance were assessed through peer nomination and the mental health outcomes of depression and anxiety were assessed through children's self-report. Teachers and parents also completed a social behavior scale for each child. Three areas of analyses were conducted pertaining to membership classification of social roles and the social acceptance and mental health outcomes associated with those roles, reporter agreement within the social roles, and the psychometric properties of the Childhood Social Behavior Scale. Results showed an overall negative pattern of adjustment for children identified as a member of any of the negative social roles. Also, the results support a new analytic approach to the investigation of social roles. The implication of these findings for early identification, social policy, and effective prevention strategies are discussed. ^

Research on the influence of behavioral forces that motivate trader behavior and sentiment: A prospect theory exegesis

This study focuses on empirical investigations and seeks implications by utilizing three different methodologies to test various aspects of trader behavior. The first methodology utilizes Prospect Theory to determine trader behavior during periods of extreme wealth contracting periods. Secondly, a threshold model to examine the sentiment variable is formulated and thirdly a study is made of the contagion effect and trader behavior. ^ The connection between consumers' sense of financial well-being or sentiment and stock market performance has been studied at length. However, without data on actual versus experimental performance, implications based on this relationship are meaningless. The empirical agenda included examining a proprietary file of daily trader activities over a five-year period. Overall, during periods of extreme wealth altering conditions, traders "satisfice" rather than choose the "best" alternative. A trader's degree of loss aversion depends on his/her prior investment performance. A model that explains the behavior of traders during periods of turmoil is developed. Prospect Theory and the data file influenced the design of the model. ^ Additional research included testing a model that permitted the data to signal the crisis through a threshold model. The third empirical study sought to investigate the existence of contagion caused by declining global wealth effects using evidence from the mining industry in Canada. Contagion, where a financial crisis begins locally and subsequently spreads elsewhere, has been studied in terms of correlations among similar regions. The results provide support for Prospect Theory in two out of the three empirical studies. ^ The dissertation emphasizes the need for specifying precise, testable models of investors' expectations by providing tools to identify paradoxical behavior patterns. True enhancements in this field must include empirical research utilizing reliable data sources to mitigate data mining problems and allow researchers to distinguish between expectations-based and risk-based explanations of behavior. Through this type of research, it may be possible to systematically exploit "irrational" market behavior. ^

Evaluating the external validity of comorbid disorders in youth using rating scales and behavior observations

To evaluate the theoretical underpinnings of current categorical approaches to classify childhood psychopathological conditions, this dissertation examined whether children with a single diagnosis of an anxiety disorder (ANX only) and children with an anxiety diagnosis comorbid with other diagnoses (i.e., anxiety + anxiety disorder [ANX + ANX], anxiety + depressive disorder [ANX + DEP], and anxiety + disruptive disorder [ANX + EXT]) could be differentiated using external validation criteria of clinical phenomenology (i.e., levels of anxiety, depression, and internalizing, externalizing and total behavior problems). This study further examined whether the four groups could be differentiated in terms of their interaction patterns with their parents and peers, respectively. The sample consisted of 129 youth and their parents who presented to the Child Anxiety and Phobia Program (CAPP) housed within the Child and Family Psychosocial Research Center at Florida International University, Miami. Youth were between the ages of 8 and 14 years old. A battery of questionnaires was used to assess participants' clinical presentation in terms of levels of anxiety, depression, and internalizing and externalizing symptoms. Family and peer interaction were evaluated through rating scales and through behavior observation tasks. Statistics based on the parameter estimates of the structured equation models indicated that all the comorbid groups were significantly different from the pure anxiety disorder group when it came to depression indices of clinical phenomenology. Further, significant differences appeared mainly in terms of the ANX + DEP comorbid group relative to the other comorbid groups. In terms of Parent-child interaction the ANX + EXT and the ANX + DEP comorbid groups were differentiated from the pure anxiety disorder and ANX + ANX comorbid group when it came to the appraisal of the parent/child relationship by the parent, and the acceptance subscale according to the mother report. In terms of peer-child interaction the ANX + EXT and the ANX + DEP comorbid groups were statistically significantly different from the pure anxiety disorder only when it came to the positive interactions and the social skills as rated by mother. Limitations and future research recommendations are discussed.

A comparative analysis of self-determined evaluations of work performance and support needs by adults with mental retardation in supported work and in sheltered workshop environments

The purpose of this study was to determine if there was a difference in the self-determined evaluations of work performance and support needs by adults with mental retardation in supported employment and in sheltered workshop environments. The instrument, Job Observation and Behavior Scale: Opportunity for Self-Determination (JOBS: OSD; Brady, Rosenberg, & Frain, 2006), was administered to 38 adults with mental retardation from sheltered workshops and 32 adults with mental retardation from supported employment environments. Cross-tabulations with Chi-square tests and independent samples t-tests were conducted to evaluate differences between the two groups, sheltered workshop and supported work. Two Multivariate Analyses of Variance (MANOVAs) were conducted to determine the effect of work environment on Quality of Performance (QP) and Types of Support (TS) test scores and their subscales. ^ This study found that there were significant differences between the groups on the QP Behavior and Job Duties subscales. The sheltered workshop group perceived themselves as performing significantly better on job duties than the supported work group. Conversely, the supported work group perceived themselves to have better behavior than the sheltered workshop group. However, there were no significant differences between groups in their perception of support needs for the three subscales. ^ The findings imply that work environment affects the self-determined evaluations of work performance by adults with mental retardation. Recommendations for further study include (a) detailing the characteristics of supported work and sheltered workshops that support and/or discourage self-determined behaviors, (b) exploring the behavior of adults with mental retardation in sheltered workshops and supported work environments, and (c) analysis of the support needs for and understanding of them by adults with mental retardation in sheltered workshops and in supported work environments. ^