Prediction of chlorine and trihalomethanes concentration profile in bulk drinking water distribution systems from laboratory data

Nearly all drinking water distribution systems experience a "natural" reduction of disinfection residuals. The most frequently used disinfectant is chlorine, which can decay due to reactions with organic and inorganic compounds in the water and by liquid/solids reaction with the biofilm, pipe walls and sediments. Usually levels of 0.2-0.5 mg/L of free chlorine are required at the point of consumption to maintain bacteriological safety. Higher concentrations are not desirable as they present the problems of taste and odour and increase formation of disinfection by-products. It is usually a considerable concern for the operators of drinking water distribution systems to manage chlorine residuals at the "optimum level", considering all these issues. This paper describes how the chlorine profile in a drinking water distribution system can be modelled and optimised on the basis of readily and inexpensively available laboratory data. Methods are presented for deriving the laboratory data, fitting a chlorine decay model of bulk water to the data and applying the model, in conjunction with a simplified hydraulic model, to obtain the chlorine profile in a distribution system at steady flow conditions. Two case studies are used to demonstrate the utility of the technique. Melbourne's Greenvale-Sydenham distribution system is unfiltered and uses chlorination as its only treatment. The chlorine model developed from laboratory data was applied to the whole system and the chlorine profile was shown to be accurately simulated. Biofilm was not found to critically affect chlorine decay. In the other case study, Sydney Water's Nepean system was modelled from limited hydraulic data. Chlorine decay and trihalomethane (THM) formation in raw and treated water were measured in a laboratory, and a chlorine decay and THM model was derived on the basis of these data. Simulated chlorine and THM profiles agree well with the measured values available. Various applications of this modelling approach are also briefly discussed.

Researching social inequalities in education : towards a Bourdieuian methodology

The injustices of ‘allowing certain people to succeed, based not upon merit but upon the cultural experiences, the social ties and the economic resources they have access to, often remains unacknowledged in the broader society’ (Wacquant, 1998, p. 216). Cognizant of this, the authors argue that education requires researchers’ renewed examination and explanation of its involvement in the construction of social and economic differences. Specifically, they make the case for researchers to consider the theoretical work of Pierre Bourdieu, outlining what they understand by a Bourdieuian methodology, which is informed by socially critical and poststructural understandings of the world. Such methodology attempts to dig beneath surface appearances, asking how social systems work. By asking ‘whose interests are being served and how’ (Tripp, 1998, p. 37) in the social arrangements we find, Bourdieu can help us to ‘work towards a more just social order’ (Lenzo, 1995, p. 17).

Schooling and the production of social inequalities : what can and should we be doing?

To speak of an ideal is to lay claim to what ought or should be and to explain 'reality' as deviation. That is, ideals serve to provide direction towards some desired goal as well as judgment about how well a perceived reality approximates that desire. In more recent times, the postmodernist critique has provided its own 'reality check' on modernist ideals, challenging the notion that there is one best way to reach Utopian ends. The emergence of postmodern theories has signalled a general shift in 'the structure of feeling'1 from acquiescence to censure of the universal. But it is not as if there are no postmodern ideals. In these accounts, utopianism is more cogently understood as 'heterotopianisms'. While we are convinced by such critique, that there are diverse goals of value and pathways to reach them, we admit to some uneasiness about a 'postmodern pluralism' in which ideals have die potential to wash away into relativism, where one ideal is as good as the next and ways of achieving them are also equally regarded.

Maternal 25-hydroxyvitamin D concentration and offspring birth size : effect modification by infant VDR genotype

Background/Objectives: We tested the hypothesis that the relationship between maternal 25-hydroxyvitamin D (25-(OH)D) and offspring birth size differs according to offspring vitamin D receptor (VDR) genotype (Apa1, Bsm1, Fok1 or Taq1).

Subjects/Methods: Mothers of 354 singleton babies had serum 25-(OH)D concentration measured at 28–30 weeks of gestation and consented to measurement of their babies soon after birth. DNA was extracted from the babies’ Guthrie cards.

Results: There was evidence of effect modification by infant FokI genotype. Babies of deficient mothers had lower birth weight with FF or Ff, but not ff genotype (P-value for interaction after adjustment for potential confounding factors=0.02), but thicker subscapular and suprailiac skinfolds with ff, but not FF or Ff genotype (P=0.008 and 0.02, respectively). Sample size was insufficient to investigate effect modification by the other VDR polymorphisms.

Conclusions: These preliminary findings suggest that studies of maternal vitamin D status and birth size may need to take VDR genotype into account.

Mathematics curriculum reform : reproducing social inequalities

This book is essential reading for Australasian mathematics educators and other researchers with an interest in the history of mathematics curriculum, the culture of mathematics, gender, and social justice issues in mathematics. Drawing on the results of research conducted by the Educational Outcomes Research Unit at the University of Melbourne and historical documents, Richard Teese argues that the education system fails to diffuse the economic and cultural benefits assumed to flow from the completion of secondary schooling.

Integral approach and numerical improvement to calculate carbon concentration profiles in carburising

The carbon diffusion in steel, where the carbon diffusivity varies with the carbon content, was solved with the integral methods under the third boundary condition. The variation of carbon diffusivity in steel with the carbon content was described with two different functions, linear dependence and exponential dependence. The integral approximation for both cases was improved with the numerical computation to more accurately predict the carbon profiles. The integral solution is more accurate than the formulation based on the assumption of a constant diffusivity or those based on the assumption of a constant diffusivity and/or constant carbon content at part surface. It is also more easily used in practice than the numerical method to describe the carburising process and predict the carbon content at steel surface and carbon profiles in treated layer.

Vitamin D-fortified milk achieves the targeted serum 25-hydroxyvitamin D concentration without affecting that of parathyroid hormone in New Zealand toddlers

For young children, the level of vitamin D required to ensure that most achieve targeted serum 25-hydroxyvitamin D [25(OH)D] ≥50 nmol/L has not been studied. We aimed to investigate the effect of vitamin D-fortified milk on serum 25(OH)D and parathyroid hormone (PTH) concentrations and to examine the dose–response relationship between vitamin D intake from study milks and serum 25(OH)D concentrations in healthy toddlers aged 12–20 mo living in Dunedin, New Zealand (latitude 46°S). Data from a 20-wk, partially blinded, randomized trial that investigated the effect of providing red meat or fortified toddler milk on the iron, zinc, iodine, and vitamin D status in young New Zealand children (n = 181; mean age 17 mo) were used. Adherence to the intervention was assessed by 7-d weighed diaries at wk 2, 7, 11, 15, and 19. Serum 25(OH)D concentration was measured at baseline and wk 20. Mean vitamin D intake provided by fortified milk was 3.7 μg/d (range, 0–10.4 μg/d). After 20 wk, serum 25(OH)D concentrations but not PTH were significantly different in the milk groups. The prevalence of having a serum 25(OH)D <50 nmol/L remained relatively unchanged at 43% in the meat group, whereas it significantly decreased to between 11 and 15% in those consuming fortified study milk. In New Zealand, vitamin D intake in young children is minimal. Our findings indicate that habitual consumption of vitamin D-fortified milk providing a mean intake of nearly 4 μg/d was effective in achieving adequate year-round serum 25(OH)D for most children.

Correlates of socio-economic inequalities in women’s television viewing : a study of intrapersonal, social and environmental mediators

Introduction

Socio-economically disadvantaged women are at a greater risk of spending excess time engaged in television viewing, a behavior linked to several adverse health outcomes. However, the factors which explain socio-economic differences in television viewing are unknown. This study aimed to investigate the contribution of intrapersonal, social and environmental factors to mediating socio-economic (educational) inequalities in women's television viewing.
Methods

Cross-sectional data were provided by 1,554 women (aged 18-65) who participated in the 'Socio-economic Status and Activity in Women study' of 2004. Based on an ecological framework, women self-reported their socio-economic position (highest education level), television viewing, as well as a number of potential intrapersonal (enjoyment of television viewing, preference for leisure-time sedentary behavior, depression, stress, weight status), social (social participation, interpersonal trust, social cohesion, social support for physical activity from friends and from family) and physical activity environmental factors (safety, aesthetics, distance to places of interest, and distance to physical activity facilities).
Results

Multiple mediating analyses showed that two intrapersonal factors (enjoyment of television viewing and weight status) and two social factors (social cohesion and social support from friends for physical activity) partly explained the educational inequalities in women's television viewing. No physical activity environmental factors mediated educational variations in television viewing.
Conclusions

Acknowledging the cross-sectional nature of this study, these findings suggest that health promotion interventions aimed at reducing educational inequalities in television viewing should focus on intrapersonal and social strategies, particularly providing enjoyable alternatives to television viewing, weight-loss/management information, increasing social cohesion in the neighborhood and promoting friend support for activity.

Tackling health inequalities : what do senior managers think

Objective: To describe how New South Wales (NSW) Area Health Service Chief Executive Officers (CEOs) understood concepts of equity in the development of NSW Health's Equity Statement; CEO knowledge and interpretation of a given concept being one aspect of developing policy.

Design and Setting: This paper describes the process through which NSW Area Health Service CEOs were involved in developing the Equity Statement, specifically:

1. Briefings with individual CEOs on key issues and identification of possible difficulties and potential 'equity champions'.
2. A two-hour workshop to explore ('pre-mortem') why the proposed statement might fail.
3. CEO involvement in identifying strategies that promoted equity already operating locally.
4. C onsultations with selected individuals about the draft recommendations.
5. Feedback to CEOs.

The article provides a case study of consultative policy making by illustrating how participant knowledge can both inform and be strengthened by involvement in the policy development process.

Results: There was a high level of awareness among CEOs of health inequalities and an acceptance of their responsibility to address them. They saw three main ways of doing this: a) equity of resource allocation for health service delivery within and between regions; b) equity of access to health services based on need; and c) equity of health outcomes. CEOs felt that making the health system accountable for health outcomes would provide pressure for system-wide resource allocation changes. They recognised that factors substantially impacting on health outcomes were outside the control of the health system. Furthermore, finding a balance to which they could be held accountable was difficult. All CEOs saw ensuring needs-based access to services as a key area where they could potentially have an impact; and they specifically saw challenges in a conflict between equity and efficiency, marginalisation of special treatment for disadvantaged people, balancing investment in rescue services and prevention/early intervention, and developing a rational health financing system. The resulting policy has been broadly embedded within the NSW health system with strong local support.

Conclusion: The NSW Health and Equity policy was embedded because CEO leadership and acceptance of the policy enhanced local ownership.