The influence of strontium on porosity formation in Al-Si alloys

Strontium modification is known to alter the amount, characteristics, and distribution of porosity in Al-Si castings. Although many theories have been proposed to account for these effects, most can be considered inadequate because of their failure to resolve contradictions and discrepancies in the literature. In an attempt to critically appraise some of these theories, the amount, distribution, and morphology of porosity were examined in sand-cast plates of Sr-free and Sr-containing pure Al, Al-l wt pet Si, and Al-9 wt pet Si alloys. Statistical significance testing was used to verify apparent trends in the porosity data. No apparent differences in the amount, distribution, and morphology of porosity were observed between Sr-free and Sr-containing alloys with no or very small eutectic volume fractions. However, Sr modification significantly changed the amount, distribution, and morphology of porosity in alloys with a significant volume fraction of eutectic. ne addition of Sr reduced porosity in the hot spot region of the casting, and the pores became well dispersed and rounded. This result can be explained by considering the combined effect of the casting design and the differences in the pattern of eutectic solidification between unmodified and Sr-modified alloys.

Issues in boys' education: A question of teacher threshold knowledges?

This paper explores the effects of specific teacher threshold knowledges about boys and gender on the implementation of a so-called 'boy friendly' curriculum at one junior secondary high school in Australia. Through semi-structured inter-views with selected staff at the school, it examines the normalizing assumptions and 'truth claims' about boys, as gendered subjects, which drive the pedagogical impetus for such a curriculum initiative. This research raises crucial questions about the need for the formulation of both school and governmental policy grounded in sound research-based knowledge about the social construction of gender and its impact on the lives of both boys and girls and their experiences of schooling. This is crucial, we argue, in light of the recent parliamentary report on boys' education in Australia which rejects gender theorizing and given the failure of key staff in the research school to interrogate the binary ways in which masculinity and femininity are socially constructed and institutionalized in schools through a particular 'gender regime'. While some good things are happening in the research school, the failure to acknowledge the social construction of gender means that ultimately the school's programs cannot be successful.

Towards an ethics of engagement in education in global times

Starting from the observation that patterns of educational inequality are widely known but largely invisible in public debates on education, this article argues for the importance of an ethics of education which challenges simple acceptance of 'things as they are'. It suggests possibilities for working with discourses of ethics, rights and citizenship in contingent and strategic ways, and argues for the importance of engaging ethically across difference in current global times. It proposes three interrelated dimensions for an ethics of engagement in education: an ethics of commitment to intellectual rigour; an ethics of civility; and an inter-human ethics of care.

Changes in use of disease-modifying anti-rheumatic drugs in Australia over the period 1992-2004

Purpose Evidence is growing that early use of disease-modifying anti-rheumatic drugs (DMARDs) and combinations of these drugs provide optimal care for people with rheumatoid arthirits. The aim of this study was to describe objectively the pattern of consumption of DMARDs in the Australian community (community-based prescribing, specialist and general practitioner) 1992-2004, and to compare this with prescribing patterns reported in other countries. Method Dispensing statistics from the Pharmaceutical Benefit Scheme (PBS-Australia's universal prescription subsidy scheme) were analysed and temporal trends evaluated. Drug consumption was calculated as the number of dispensed defined daily doses (DDD)/1000 inhabitants/day (WHO ATC/DDD classification 2005). Results The consumption of DMARDs in the Australian community increased steadily from 2.6 DDD/1000 inhabitants/ day in 1992 to 5.5 DDD/1000 inhabitants/day. Over the period 1992-2004, methotrexate (MTX) was the most commonly used DMARD (from 0.6 to 3.0 DDD/1000 inhabitants/day). Consumption of gold (parentcral and oral) and penicillamine declined during this time. The inclusion of leflunomide on the PBS in 2000 contributed to the increase in DMARD usage. Conclusion Use of DMARDs within the Australian community has increased in recent years, coinciding with the change in guidelines for therapy for rheumatoid arthritis (RA) to earlier use of DMARDs and the more common use of combinations. This study used DDD methodology to quantify trends for DMARD consumption and these trends are broadly consistent with international prescribing patterns assessed using different methodologies. Copyright (c) 2006 John Wiley & Sons, Ltd.

Ecology - Corals fail a test of neutrality

Ecologists continue to wrestle with a central question in biodiversity studies — the prediction of species’ distributions in various environments. A merger of different theories is the long-term prospect.

Fighting, anger, frustration and tears: Matthew's story of hegemonic masculinity

This paper draws on Matthew's story to illustrate the conflicting discourses of being a boy and being a student. Matthew is 12 years old and in Grade Six, his final year at Banrock Primary ( a K- 6 Australian State School). School is far from a happy place for Matthew - his tearful accounts of his combative relationships with his peers and his teacher highlight his emotional distress. The paper's analytic focus draws attention to some of the ways Matthew's harmful storylines of hegemonic masculinity are made possible through, in particular, his teacher's gendered philosophies and her strategies of individualism and control. In this regard, Matthew's story provides insight into the potentially counterproductive realities of teacher practice in relation to addressing issues of masculinity within the school environment. Against this backdrop, the paper stresses the importance of teachers drawing on a sound research-based framework of gender knowledges that can illuminate how masculinities are constructed, regulated and, indeed, transformed through the power relations of everyday social practice, including teacher practice.

'Please Mr Hay, what are my poss(abilities)?': Legitimation of ability through physical education practices

This paper provides two vignettes that draw on data from projects that interrogate how a student can be positioned by practices within physical education (PE) and directed by the PE teacher in relation to their valued or legitimated ability. Through the use of Pierre Bourdieu's conceptual tools of field, habitus and capital we investigate the complex legitimation processes that shape student poss(abilities) and that are situated in the space of the PE class. The first vignette is from the perspective of a student and draws on data from interviews, a journal, questionnaires and photos of her PE experiences in upper primary and lower secondary school. The second vignette focuses on teacher practices and his constitution of the field of a PE class highlighting the significance of teacher perspectives of 'ability' in informing assessment in senior secondary PE. Using these examples we discuss the symbolic violence that works against each student by positioning them as 'less able' or 'unable' despite their participation in a learning context. We argue that by not attending to the possible abilities of students that could have been recognized, developed and legitimated, and through the misuse of capital assignment by teachers, PE may well be counterproductive to students' ongoing engagement with the subject area and the espoused potential upon which such a subject area justifies itself.