Contrast enhancement of EPID images via difference imaging : a feasibility study

In this study, the feasibility of difference imaging for improving the contrast of electronic portal imaging device (EPID) images is investigated. The difference imaging technique consists of the acquisition of two EPID images (with and without the placement of an additional layer of attenuating medium on the surface of the EPID)and the subtraction of one of these images from the other. The resulting difference image shows improved contrast, compared to a standard EPID image, since it is generated by lower-energy photons. Results of this study show that, ¯rstly, this method can produce images exhibiting greater contrast than is seen in standard megavoltage EPID images and that, secondly, the optimal thickness of attenuating material for producing a maximum contrast enhancement may vary with phantom thickness and composition. Further studies of the possibilities and limitations of the di®erence imaging technique, and the physics behind it, are therefore recommended.

Aboriginal public health and education : has it made a difference in practice?

Over the years, public health in relation to Australian Aboriginal people has involved many individuals and groups including health professionals, governments, politicians, special interest groups and corporate organisations. Since colonisation commenced until the1980s, public health relating to Aboriginal and Torres Strait Islander people was not necessarily in the best interests of Aboriginal and Torres Strait Islander people, but rather in the interests of the non-Aboriginal population. The attention that was paid focussed more generally around the subject of reproduction and issues of prostitution, exploitation, abuse and venereal diseases (Kidd, 1997). Since the late 1980s there has been a shift in the broader public health agenda (see Baum, 1998) along with public health in relation to Aboriginal and Torres Strait Islander people (NHMRC, 2003). This has been coupled with increasing calls to develop appropriate tertiary curriculum and to educate, train, and employ more Aboriginal and Torres Strait Islander and non-Aboriginal people in public health (Anderson et al., 2004; Genat, 2007; PHERP, 2008a, 2008b). Aboriginal and Torres Strait Islander people have been engaged in public health in ways in which they are in a position to influence the public health agenda (Anderson 2004; 2008; Anderson et al., 2004; NATSIHC, 2003). There have been numerous projects, programs and strategies that have sought to develop the Aboriginal and Torres Strait Islander Public Health workforce (AHMAC, 2002; Oldenburg et al., 2005; SCATSIH, 2002). In recent times the Aboriginal community controlled health sector has joined forces with other peak bodies and governments to find solutions and strategies to improve the health outcomes of Aboriginal and Torres Strait Islander peoples (NACCHO & Oxfam, 2007). This case study chapter will not address these broader activities. Instead it will explore the activities and roles of staff within the Public Health and Research Unit (PHRU) at the Victorian Aboriginal Community Controlled Health Organisation (VACCHO). It will focus on their experiences with education institutions, their work in public health and their thoughts on gaps and where improvements can be made in public health, research and education. What will be demonstrated is the diversity of education qualifications and experience. What will also be reflected is how people work within public health on a daily basis to enact change for equity in health and contribute to the improvement of future health outcomes of the Victorian Aboriginal community.

A two-Dimensional finite volume method for variable density flow and solute transport through saturated-unsaturated media

Extensive groundwater withdrawal has resulted in a severe seawater intrusion problem in the Gooburrum aquifers at Bundaberg, Queensland, Australia. Better management strategies can be implemented by understanding the seawater intrusion processes in those aquifers. To study the seawater intrusion process in the region, a two-dimensional density-dependent, saturated and unsaturated flow and transport computational model is used. The model consists of a coupled system of two non-linear partial differential equations. The first equation describes the flow of a variable-density fluid, and the second equation describes the transport of dissolved salt. A two-dimensional control volume finite element model is developed for simulating the seawater intrusion into the heterogeneous aquifer system at Gooburrum. The simulation results provide a realistic mechanism by which to study the convoluted transport phenomena evolving in this complex heterogeneous coastal aquifer.

Towards making a difference through a university-TAFE partnership : mentoring potential teacher aides

Universities promote partnerships as an investment of social capital that may benefit communities. Mentoring of university students in schools has become key to induction of education workplace practices. One such arrangement is the mentoring of students from TAFE who endeavour to become teacher aides. However, there is no theoretical model for mentoring teacher aides and, similar to mentoring preservice teachers, such practices vary in quality and quantity. What are mentors’ perceptions of mentoring potential teacher aides within school settings? This mixed-method research involves a survey with extended responses. The aim is to determine practices and strategies for mentoring potential teacher aides (PTAs). Results indicated that PTAs require induction about the school culture and infrastructure, which includes ethics, values, operational plans, awareness of facilities and a range of other inductions that would aid the PTA’s work practices. Findings also revealed that many of the mentoring practices employed for preservice teachers may be used for mentoring PTAs in school settings. Indeed, mentors require personal attributes to facilitate the mentoring process. They also indicated outlining the education system requirements as fundamental to workplace operations. In addition, as most PTAs work with students in the classroom, the mentor’s pedagogical knowledge can further assist PTAs to develop an understanding of effective pedagogical practices, particularly for small groups or one-on-one sessions. Finally, a mentor’s modelling of practices and providing constructive feedback about the PTA’s practices can assist the development of workplace operations. In conclusion, the survey employed in this study may assist organisations to develop protocols of practice for workplace mentors. PTAs require mentors who are versed in effective mentoring practices that can more readily guide them towards success.

Tsunami alert : the difference a phone makes

As a new communication technology expands in a disadvantaged, rural area of a developing country, this process of change can radically affect the quality and volume of available information. Substantial growth has occurred in the telecommunication sector in Papua New Guinea (PNG) in the last three years. Mobile telephony is rapidly rolling out to rural and remote localities, following decades of inadequate service provision. The paper examines the introduction of mobile telephones into a rural village in PNG, and focuses on an example of changed information access afforded by the mobile telephone, through comparing the village’s experience of two tsunami alerts: one immediately prior to the introduction of mobile phone services in the area, and the other two years after mobile phone reception became available. The research demonstrates a key application of newly introduced information and communication technologies - to benefit disadvantaged, rural communities in emergency situations.

Difference in mosquito species (Diptera: Culicidae) and the transmission of Ross River Virus between coastline and inland areas in Brisbane, Australia

This study examined the distribution of major mosquito species and their roles in the transmission of Ross River virus (RRV) infection for coastline and inland areas in Brisbane, Australia (27°28′ S, 153°2′ E). We obtained data on the monthly counts of RRV cases in Brisbane between November 1998 and December 2001 by statistical local areas from the Queensland Department of Health and the monthly mosquito abundance from the Brisbane City Council. Correlation analysis was used to assess the pairwise relationships between mosquito density and the incidence of RRV disease. This study showed that the mosquito abundance of Aedes vigilax (Skuse), Culex annulirostris (Skuse), and Aedes vittiger (Skuse) were significantly associated with the monthly incidence of RRV in the coastline area, whereas Aedes vigilax, Culex annulirostris, and Aedes notoscriptus (Skuse) were significantly associated with the monthly incidence of RRV in the inland area. The results of the classification and regression tree (CART) analysis show that both occurrence and incidence of RRV were influenced by interactions between species in both coastal and inland regions. We found that there was an 89% chance for an occurrence of RRV if the abundance of Ae. vigifax was between 64 and 90 in the coastline region. There was an 80% chance for an occurrence of RRV if the density of Cx. annulirostris was between 53 and 74 in the inland area. The results of this study may have applications as a decision support tool in planning disease control of RRV and other mosquito-borne diseases.

(Dia)logics of difference : disability, performance & spectatorship

In this paper I examine the way artists with disabilities use performances in public spaces to encourage people to reflect on their own contribution to the construction of publics, or counter-publics, during and after the moment of encounter. I focus on Liz Crow’s Resistance on the Plinth. This is the title Crow gave her performance on the Forth Plinth in Trafalgar Square as part of Antony Gormley’s One and Other project in 2009. Described as a public art project presenting a portrait of the U.K., Gormley’s One and Other gave 2400 people selected at random via a lottery the chance to do whatever they chose for an hour on the vacant Forth Plinth in Trafalgar Square. In her hour, Crow chose to present herself in a Nazi uniform, in her wheelchair. In this paper, I discuss how Crow’s performance used a counterposition of images – the Nazi uniform, associated with eugenics and a desire to eliminate people who do not accord with the Arayan ‘norm’, counterposed with her wheelchair – to encourage passersby to “stop, look, think.” I examine how Crow used this counterposition to prevent passersby from attributing a single, stable, monologic meaning to the image – forestalling the risk that passersby would read the image as a Nazi on the Plinth – and instead draw passersby into a dialogue in which the impossibility of reconciling the contradictory images, ideologies and cultural logics Crow embodied encouraged people to continue thinking and talking about these cultural logics during and after the encounter.

Linear stern waves in finite depth channels

This paper formulates an analytically tractable problem for the wake generated by a long flat bottom ship by considering the steady free surface flow of an inviscid, incompressible fluid emerging from beneath a semi-infinite rigid plate. The flow is considered to be irrotational and two-dimensional so that classical potential flow methods can be exploited. In addition, it is assumed that the draft of the plate is small compared to the depth of the channel. The linearised problem is solved exactly using a Fourier transform and the Wiener-Hopf technique, and it is shown that there is a family of subcritical solutions characterised by a train of sinusoidal waves on the downstream free surface. The amplitude of these waves decreases as the Froude number increases. Supercritical solutions are also obtained, but, in general, these have infinite vertical velocities at the trailing edge of the plate. Consideration of further terms in the expansions suggests a way of canceling the singularity for certain values of the Froude number.

Reverse engineering and finite element analysis of a 3-wheeler automotive structure

Auto rickshaws (3-wheelers) are the most sought after transport among the urban and rural poor in India. The assembly of the vehicle involves assemblies of several major components. The L-angle is the component that connects the front panel with the vehicle floor. Current L-angle part has been observed to experience permanent deformation failure over period of time. This paper studies the effect of the addition of stiffeners on the L-angle to increase the strength of the component. A physical model of the L-angle was reversed engineered and modelled in CAD before static loading analysis were carried out on the model using finite element analysis. The modified L-angle fitted with stiffeners was shown to be able to withstand more load compare to previous design.

Generalised finite volume strategies for simulating transport in strongly orthotropic porous media

In this work two different finite volume computational strategies for solving a representative two-dimensional diffusion equation in an orthotropic medium are considered. When the diffusivity tensor is treated as linear, this problem admits an analytic solution used for analysing the accuracy of the proposed numerical methods. In the first method, the gradient approximation techniques discussed by Jayantha and Turner [Numerical Heat Transfer, Part B: Fundamentals, 40, pp.367–390, 2001] are applied directly to the

The mechanical heterogeneity of the hard callus influences local tissue strains during bone healing : a finite element study based on sheep experiments

During secondary fracture healing, various tissue types including new bone are formed. The local mechanical strains play an important role in tissue proliferation and differentiation. To further our mechanobiological understanding of fracture healing, a precise assessment of local strains is mandatory. Until now, static analyses using Finite Elements (FE) have assumed homogenous material properties. With the recent quantification of both the spatial tissue patterns (Vetter et al., 2010) and the development of elastic modulus of newly formed bone during healing (Manjubala et al., 2009), it is now possible to incorporate this heterogeneity. Therefore, the aim of this study is to investigate the effect of this heterogeneity on the strain patterns at six successive healing stages. The input data of the present work stemmed from a comprehensive cross-sectional study of sheep with a tibial osteotomy (Epari et al., 2006). In our FE model, each element containing bone was described by a bulk elastic modulus, which depended on both the local area fraction and the local elastic modulus of the bone material. The obtained strains were compared with the results of hypothetical FE models assuming homogeneous material properties. The differences in the spatial distributions of the strains between the heterogeneous and homogeneous FE models were interpreted using a current mechanobiological theory (Isakson et al., 2006). This interpretation showed that considering the heterogeneity of the hard callus is most important at the intermediate stages of healing, when cartilage transforms to bone via endochondral ossification.

Assembling dynamic repertoires of literate practices : teaching that makes a difference

This chapter considers how teachers can make a difference to the kinds of literacy young people take up. Increasingly, researchers and policy-makers see literacy as an ensemble of socio-cultural situated practices rather than as a unitary skill. Accordingly, the differences in what young people come to do with literacy, in and out of school, confront us more directly. If literacy development involves assembling dynamic repertoires of practices, it is crucial to consider what different groups of children growing up and going to school in different places have access to and make investments in over time; the kinds of literate communities from which some are excluded or included; and how educators make a difference to the kinds of literate trajectories and identities young people put together.

Probabilistic subgroup identification using Bayesian finite mixture modelling : a case study in Parkinson’s disease phenotype identification

This article explores the use of probabilistic classification, namely finite mixture modelling, for identification of complex disease phenotypes, given cross-sectional data. In particular, if focuses on posterior probabilities of subgroup membership, a standard output of finite mixture modelling, and how the quantification of uncertainty in these probabilities can lead to more detailed analyses. Using a Bayesian approach, we describe two practical uses of this uncertainty: (i) as a means of describing a person’s membership to a single or multiple latent subgroups and (ii) as a means of describing identified subgroups by patient-centred covariates not included in model estimation. These proposed uses are demonstrated on a case study in Parkinson’s disease (PD), where latent subgroups are identified using multiple symptoms from the Unified Parkinson’s Disease Rating Scale (UPDRS).