Estimating mean exposures from censored data: exposure to benzene in the Australian petroleum industry

A retrospective assessment of exposure to benzene was carried out for a nested case control study of lympho-haematopoietic cancers, including leukaemia, in the Australian petroleum industry. Each job or task in the industry was assigned a Base Estimate (BE) of exposure derived from task-based personal exposure assessments carried out by the company occupational hygienists. The BEs corresponded to the estimated arithmetic mean exposure to benzene for each job or task and were used in a deterministic algorithm to estimate the exposure of subjects in the study. Nearly all of the data sets underlying the BEs were found to contain some values below the limit of detection (LOD) of the sampling and analytical methods and some were very heavily censored; up to 95% of the data were below the LOD in some data sets. It was necessary, therefore, to use a method of calculating the arithmetic mean exposures that took into account the censored data. Three different methods were employed in an attempt to select the most appropriate method for the particular data in the study. A common method is to replace the missing (censored) values with half the detection limit. This method has been recommended for data sets where much of the data are below the limit of detection or where the data are highly skewed; with a geometric standard deviation of 3 or more. Another method, involving replacing the censored data with the limit of detection divided by the square root of 2, has been recommended when relatively few data are below the detection limit or where data are not highly skewed. A third method that was examined is Cohen's method. This involves mathematical extrapolation of the left-hand tail of the distribution, based on the distribution of the uncensored data, and calculation of the maximum likelihood estimate of the arithmetic mean. When these three methods were applied to the data in this study it was found that the first two simple methods give similar results in most cases. Cohen's method on the other hand, gave results that were generally, but not always, higher than simpler methods and in some cases gave extremely high and even implausible estimates of the mean. It appears that if the data deviate substantially from a simple log-normal distribution, particularly if high outliers are present, then Cohen's method produces erratic and unreliable estimates. After examining these results, and both the distributions and proportions of censored data, it was decided that the half limit of detection method was most suitable in this particular study.

Ice and pulsed electromagnetic field to reduce pain and swelling after distal radius fractures

Objective: To examine the relative effectiveness of ice therapy and/or pulsed electromagnetic field in reducing pain and swelling after the immobilization period following a distal radius fracture.Methods: A total of 83 subjects were randomly allocated to receive 30 minutes of either ice plus pulsed electromagnetic field (group A); ice plus sham pulsed electromagnetic field (group B); pulsed electromagnetic field alone (group C), or sham pulsed electromagnetic field treatment for 5 consecutive days (group D). All subjects received a standard home exercise programme. A visual analogue scale was used for recording pain; volumetric displacement for measuring the swelling of the forearm; and a hand-held goniometer for measuring the range of wrist motions before treatment on days 1, 3 and 5.Results: At day 5, a significantly greater cumulative reduction in the visual analogue scores as well as ulnar deviation range of motion was found in group A than the other 3 groups. For volumetric measurement and pronation, participants in group A performed better than subjects in group D but not those in group B.Conclusion: The addition of pulsed electromagnetic field to ice therapy produces better overall treatment outcomes than ice alone, or pulsed electromagnetic field alone in pain reduction and range of joint motion in ulnar deviation and flexion for a distal radius fracture after an immobilization period of 6 weeks.

Subcultural capital and the female 'underclass'? A feminist response to an underclass discourse

It is often argued that economically marginalized young women occupy a school and post-school underclass, and that this underclass has a particular culture associated with it. Such views provoke a profound ambivalence in many of those who work with such young people. On the one hand, they are anxious to acknowledge the culture of the communities to which marginalized young women belong. On the other hand, they wish to avoid the pernicious implications of underclass theories that suggest disadvantage is the result of the culture and values of marginalized social groupings. This paper offers an overview and feminist critique of the structuralist and cultural or behaviourist strands of underclass theory. It focuses particularly on the work of Charles Murray, a major proponent of the culturalist perspective and the representation of the single mother in this discourse. It then considers how a less punitive theorization of marginalized cultures might be achieved by drawing on and adapting concepts from Pierre Bourdieu's sociology. The paper reflects on how such ideas might serve as a way of exploring how gender impacts on the forms of cultural capital available to young women in difficult economic circumstances.

If the Tasmanian Tiger were found, what should we do? An interdisciplinary guide to endangered species recovery

The Tasmanian tiger, or thylacine (Thylacinus cynocephalus), is a wolf-like carnivorous marsupial last reported in the 1930s in Tasmania, an island state of Australia. Although the species is likely extinct, sightings are reported annually. A fictional scenario is described in which a female thylacine with four pouched young is captured. This scenario is explored and an interdisciplinary approach to endangered species recovery is introduced. This approach is applicable to all endangered species recovery efforts and focuses on the principal dimensions of recovery: (1) orienting to the problem at hand and meeting it successfully; (2) understanding the recovery effort itself, its full context, and the required management (decision) process; (3) using a broad range of methods; and (4) integrating research results into a comprehensive recovery process (picture of the whole). By using this interdisciplinary approach, recovery can be systematically understood, best managed, and restoration prospects enhanced.

Empowering practitioners to critically examine their current practice

A Self-Assessment Manual (SAM) for early childhood practitioners has been developed around the previously reported framework (Raban, Waniganayake, Deans, Brown & Reynolds, 2003a), and this has been piloted in a number of early childhood settings. When engaging in self reflection using SAM, practitioners collaborate with mentors from the Early Childhood Consortium Victoria (ECCV) to consider their past, present and future professional experiences. This process empowers practitioners to critically examine their current practice and plan for their future professional development in a more systematic way. SAM is seen here to serve dual purposes: on the one hand, it is an evaluative instrument that can direct professional development of individual practitioners. On the other hand, it is a research tool aimed at identifying theoretical assumptions underpinning professional practice, and allows a longitudinal approach to mapping professional growth and development. Either way, it has the potential to enhance the quality of early childhood experiences for preschool children regardless of the settings in which they may find themselves. This paper presents a formative evaluation of this work and discusses its potential for professional development planning.

On-track to what? Foucauldian analysis of Victorian post-compulsory education policy

Current ideas of adolescent development portray a slow steady movement toward adulthood. These notions developed hand in hand with social practices that evolved in the latter half of the 19th century and contemporaneously with modernisation. During this period conceptions of adolescence included longer stays in school, organised leisure activities, juvenile justice policies and the protection of youth from child labour. Lesko (2001) works from a position that the modern age is defined by time, an understanding that events and change are meaningful in their occurrence in and through time. She examines adolescence as partaking of panoptical time which is condensed and commodified; a time framework that compels us - scholars, educators, parents, and teenagers - to attend to progress, precocity, arrest, or decline" (2001 p.41). Panoptical time can be used to explore how ideas of what is 'normal' development can be used to privilege particular ways of being an adolescent, to monitor who is deemed to be 'at risk' of not conforming to that model and to govern their behaviour. A Foucauldian analysis suggests the formation of 'at risk' identities reflects historically specific discourses. An understanding of how these and other discursive constructions are formed opens the way for resistance. This presentation explores the recent implementation of On-Track and On-Track Connect within Victorian government policy and explores the experience of a Local Learning and Employment Network in implementing the policy.