Correcting radiation survey data to account for increased leakage during intensity modulated radiotherapy treatments

Purpose Intensity modulated radiotherapy (IMRT) treatments require more beam-on time and produce more linac head leakage to deliver similar doses to conventional, unmodulated, radiotherapy treatments. It is necessary to take this increased leakage into account when evaluating the results of radiation surveys around bunkers that are, or will be, used for IMRT. The recommended procedure of 15 applying a monitor-unit based workload correction factor to secondary barrier survey measurements, to account for this increased leakage when evaluating radiation survey measurements around IMRT bunkers, can lead to potentially-costly over estimation of the required barrier thickness. This study aims to provide initial guidance on the validity of reducing the value of the correction factor when applied to different radiation barriers (primary barriers, doors, maze walls and other walls) by 20 evaluating three different bunker designs. Methods Radiation survey measurements of primary, scattered and leakage radiation were obtained at each of five survey points around each of three different radiotherapy bunkers and the contribution of leakage to the total measured radiation dose at each point was evaluated. Measurements at each survey point were made with the linac gantry set to 12 equidistant positions from 0 to 330o, to 25 assess the effects of radiation beam direction on the results. Results For all three bunker designs, less than 0.5% of dose measured at and alongside the primary barriers, less than 25% of the dose measured outside the bunker doors and up to 100% of the dose measured outside other secondary barriers was found to be caused by linac head leakage. Conclusions Results of this study suggest that IMRT workload corrections are unnecessary, for 30 survey measurements made at and alongside primary barriers. Use of reduced IMRT workload correction factors is recommended when evaluating survey measurements around a bunker door, provided that a subset of the measurements used in this study are repeated for the bunker in question. Reduction of the correction factor for other secondary barrier survey measurements is not recommended unless the contribution from leakage is separetely evaluated.

The role of immunoglobulins and their transporters in urogenital Chlamydial infections

Chlamydia trachomatis infections of the male and female reproductive tracts are the world's leading sexually transmitted bacterial disease, and can lead to damaging pathology, scarring and infertility. The resolution of chlamydial infection requires the development of adaptive immune responses to infection, and includes cell-mediated and humoral immunity. Whilst cluster of differentiation (CD)4+ T cells are known to be essential in clearance of infection [1], they are also associated with immune cell infiltration, autoimmunity and infertility in the testes [2-3]. Conversely, antibodies are less associated with inflammation, are readily transported into the reproductive tracts, and can offer lumenal neutralization of chlamydiae prior to infection. Antibodies, or immunoglobulins (Ig), play a supportive role in the resolution of chlamydial infections, and this thesis sought to define the function of IgA and IgG, against a variety of chlamydial antigens expressed during the intracellular and extracellular stages of the chlamydial developmental cycle. Transport of IgA and IgG into the mucosal lumen is facilitated by receptor-mediated transcytosis yet the expression profile (under normal conditions and during urogenital chlamydial infection) of the polymeric immunoglobulin receptor (pIgR) and the neonatal Fc receptor (FcRn) remains unknown. The expression profile of pIgR and FcRn in the murine male reproductive tract was found to be polarized to the lower and upper reproductive tract tissues respectively. This demonstrates that the two receptors have a tissue tropism, which must be considered when targeting pathogens that colonize different sites. In contrast, the expression of pIgR and FcRn in the female mouse was found to be distributed in both the upper and lower reproductive tracts. When urogenitally infected with Chlamydia muridarum, both male and female reproductive tracts up-regulated expression of pIgR and down-regulated expression of FcRn. Unsurprisingly, the up-regulation of pIgR increased the concentration of IgA in the lumen. However, down-regulation of FcRn, prevented IgG uptake and led to an increase or pooling of IgG in lumenal secretions. As previous studies have identified the importance of pIgR-mediated delivery of IgA, as well as the potential of IgA to bind and neutralize intracellular pathogens, IgA against a variety of chlamydial antigens was investigated. The protection afforded by IgA against the extracellular antigen major outer membrane protein (MOMP), was found to be dependent on pIgR expression in vitro and in vivo. It was also found that in the absence of pIgR, no protection was afforded to mice previously immunized with MOMP. The protection afforded from polyclonal IgA against the intracellular chlamydial antigens; inclusion membrane protein A (IncA), inclusion membrane proteins (IncMem) and secreted chlamydial protease-like activity factor (CPAF) were produced and investigated in vitro. Antigen-specific intracellular IgA was found to bind to the respective antigen within the infected cell, but did not significantly reduce inclusion formation (p > 0.05). This suggests that whilst IgA specific for the selected antigens was transported by pIgR to the chlamydial inclusion, it was unable to prevent growth. Similarly, immunization of male mice with intracellular chlamydial antigens (IncA or IncMem), followed by depletion CD4+ T cells, and subsequent urogenital C. muridarum challenge, provided minimal pIgR-mediated protection. Wild type male mice immunized with IncA showed a 57 % reduction (p < 0.05), and mice deficient in pIgR showed a 35 % reduction (p < 0.05) in reproductive tract chlamydial burden compared to control antigen, and in the absence of CD4+ T cells. This suggests that pIgR and secretory IgA (SIgA) were playing a protective role (21 % pIgR-mediated) in unison with another antigen-specific immune mechanism (36 %). Interestingly, IgA generated during a primary respiratory C. muridarum infection did not provide a significant amount of protection to secondary urogenital C. muridarum challenge. Together, these data suggest that IgA specific for an extracellular antigen (MOMP) can play a strong protective role in chlamydial infections, and that IgA targeting intracellular antigens is also effective but dependent on pIgR expression in tissues. However, whilst not investigated here, IgA targeting and blocking other intracellular chlamydial antigens, that are more essential for replication or type III secretion, may be more efficacious in subunit vaccines. Recently, studies have demonstrated that IgG can neutralize influenza virus by trafficking IgG-bound virus to lysosomes [4]. We sought to determine if this process could also traffic chlamydial antigens for degradation by lysosomes, despite Chlamydia spp. actively inhibiting fusion with the host endocytic pathway. As observed in pIgR-mediated delivery of anti-IncA IgA, FcRn similarly transported IgG specific for IncA which bound the inclusion membrane. Interestingly, FcRn-mediated delivery of anti-IncA IgG significantly decreased inclusion formation by 36 % (p < 0.01), and induced aberrant inclusion morphology. This suggests that unlike IgA, IgG can facilitate additional host cellular responses which affect the intracellular niche of chlamydial growth. Fluorescence microscopy revealed that IgG also bound the inclusion, but unlike influenza studies, did not induce the recruitment of lysosomes. Notably, anti-IncA IgG recruited sequestosomes to the inclusion membrane, markers of the ubiquitin/proteasome pathway and major histocompatibility complex (MHC) class I loading. To determine if the protection against C. muridarum infection afforded by IncA IgG in vitro translated in vivo, wild type mice and mice deficient in functional FcRn and MHC-I, were immunized, depleted of CD4+, and urogenitally infected with C. muridarum. Unlike in pIgR-deficient mice, the protection afforded from IncA immunization was completely abrogated in mice lacking functional FcRn and MHC-I/CD8+. Thus, both anti-IncA IgA and IgG can bind the inclusion in a pIgR and FcRn-mediated manner, respectively. However, only IgG mediates a higher reduction in chlamydial infection in vitro and in vivo suggesting more than steric blocking of IncA had occurred. Unlike anti-MOMP IgA, which reduced chlamydial infection of epithelial cells and male mouse tissues, IgG was found to enhance infectivity in vitro, and in vivo. Opsonization of EBs with MOMP-IgG enhanced inclusion formation of epithelial cells in a MOMP-IgG dose-dependent and FcRn-dependent manner. When MOMP-IgG opsonized EBs were inoculated into the vagina of female mice, a small but non-significant (p > 0.05) enhancement of cervicovaginal C. muridarum shedding was observed three days post infection in mice with functional FcRn. Interestingly, infection with opsonized EBs reduced the intensity of the peak of infection (day six) but protracted the duration of infection by 60 % in wild type mice only. Infection with EBs opsonized in IgG also significantly increased (p < 0.05) hydrosalpinx formation in the oviducts and induced lymphocyte infiltration uterine horns. As MOMP is an immunodominant antigen, and is widely used in vaccines, the ability of IgG specific to extracellular chlamydial antigens to enhance infection and induce pathology needs to be considered. Together, these data suggest that immunoglobulins play a dichotomous role in chlamydial infections, and are dependent on antigen specificity, FcRn and pIgR expression. FcRn was found to be highly expressed in upper male reproductive tract, whilst pIgR was dominantly expressed in the lower reproductive tract. Conversely, female mice expressed FcRn and pIgR in both the lower and upper reproductive tracts. In response to a normal chlamydial infection, pIgR is up-regulated increasing secretory IgA release, but FcRn is down-regulated preventing IgG uptake. Similarly to other studies [5-6], we demonstrate that IgA and IgG generated during primary chlamydial infections plays a minor role in recall immunity, and that antigen-specific subunit vaccines can offer more protection. We also show that both IgA and IgG can be used to target intracellular chlamydial antigens, but that IgG is more effective. Finally, IgA against the extracellular antigen MOMP can afford protection, whist IgG plays a deleterious role by increasing infectivity and inducing damaging immunopathology. Further investigations with additional antigens or combination subunit vaccines will enhance our understanding the protection afforded by antibodies against intracellular and extracellular pathogenic antigens, and help improve the development of an efficacious chlamydial vaccine.

The experience of being an advanced practice nurse within Australian acute care settings : a systematic review of qualitative evidence

Background There is a vast amount of international literature which, although agreeing on the need for advanced practice nurse roles, simultaneously debates and discusses the difficulties with nomenclature, definition and subsequent implementation of such roles. Due to this ambiguity it is difficult to equally compare evidence in this field across different countries. A context-specific systematic review on the qualitative evidence of the experience of being an advanced practice nurse in Australia has not been undertaken previously, however it is imperative for nursing managers and leaders to understand the complexities of advanced nursing roles in order to effectively utilise and retain these experienced and valuable nurses. With the creation of a national nursing regulating authority in 2010, it is timely to explore in-depth the experience of being an advanced practice nurse from a national perspective. Objective To identify the experience of being an advanced practice nurse working in Australian acute care settings. Inclusion criteria -Types of participants Registered nurses working in advanced practice roles in acute care settings throughout Australia. -Phenomena of interest The experience of being an advanced practice registered nurse working in an Australian acute care setting, as reported by the nurses themselves. -Types of studies Interpretive qualitative studies including designs such as phenomenology, grounded theory and ethnography. -Search strategy A three step search strategy was used to identify published and unpublished studies. The search process was conducted from August to October 2011 and considered published and unpublished studies from 1990 to October 2011. -Methodological quality Studies were appraised for methodological quality by two independent reviewers using the Joanna Briggs Qualitative Assessment and Review Instrument. -Data extraction Data was extracted from the papers included in the review using the standardised Joanna Briggs Institute Qualitative Assessment and Review Instrument data extraction tool. -Data synthesis Research findings were pooled using the Joanna Briggs Institute Qualitative Data and Review Instrument. Results Three published studies and one unpublished dissertation were included in the review. From these four studies, 216 findings were extracted, forming 18 categories which were then analysed to create six synthesised findings. Six meta-syntheses under the headings of expert knowledge, confidence, education, relationships, negative experiences and patient centred experience were formed from the findings. Conclusions The synthesised findings confirm that the experience of advanced practice nurses in Australian acute care settings is complex and greatly influenced personally and professionally by the organisation as well as the unpredictable nature of working with people.

Cloud computing : how does it differ from IT outsourcing and what are the implications for practice and research?

The purpose of this paper is to provide an evolutionary perspective of cloud computing (CC) by integrating two previously disparate literatures: CC and information technology outsourcing (ITO). We review the literature and develop a framework that highlights the demand for the CC service, benefits, risks, as well as risk mitigation strategies that are likely to influence the success of the service. CC success in organisations and as a technology overall is a function of (i) the outsourcing decision and supplier selection, (ii) contractual and relational governance, and (iii) industry standards and legal framework. Whereas CC clients have little control over standards and/or the legal framework, they are able to influence other factors to maximize the benefits while limiting the risks. This paper provides guidelines for (potential) cloud computing users with respect to the outsourcing decision, vendor selection, service-level-agreements, and other issues that need to be addressed when opting for CC services. We contribute to the literature by providing an evolutionary and holistic view of CC that draws on the extensive literature and theory of ITO. We conclude the paper with a number of research paths that future researchers can follow to advance the knowledge in this field.

Adapting an argumentation framework for online discourse analysis : a knowledge building approach

The use of online tools to support teaching and learning is now commonplace within educational institutions, with many of these institutions mandating or strongly encouraging the use of a blended learning approach to teaching and learning. Consequently, these institutions generally adopt a learning management system (LMS), with a fixed set of collaborative tools, in the belief that effective teaching and learning approaches will be used, to allow students to build knowledge. While some studies into the use of an LMS’s still identify continued didactic approaches to teaching and learning, the focus of this paper is on the ability of collaborative tools such as discussion forums, to build knowledge. In the context of science education, argumentation is touted as playing an important role in this process of knowledge building. However, there is limited research into argumentation in other domains using online discussion and a blended learning approach. This paper describes a study, using design research, which adapts a framework for argumentation that can be applied to other domains. In particular it will focus on an adapted social argumentation schema to identify argument in a discussion forum of N=16 participants in a secondary High School.

Do drinking and riding mix? Effects of legal doses of alcohol on balance ability in experienced motorcyclists

The appropriateness of applying drink driving legislation to motorcycle riding has been questioned as there may be fundamental differences in the effects of alcohol on these two activities. For example, while the distribution of blood alcohol content (BAC) levels among fatally injured male drivers compared to riders is similar, a greater proportion of motorcycle fatalities involve levels in the lower (0 to .10% BAC) range. Several psychomotor and higher-order cognitive skills underpinning riding performance appear to be significantly influenced by low levels of alcohol. For example, at low levels (.02 to .046% BAC), riders show significant increases in reaction time to hazardous stimuli, inattention to the riding task, performance errors such as leaving the roadway and a reduced ability to complete a timed course. It has been suggested that alcohol may redirect riders’ focus from higher-order cognitive skills to more physical skills such as maintaining balance. As part of a research program to investigate the potential benefits of introducing a zero, or reduced, BAC for all riders in Queensland regardless of their licence status, the effects of low doses of alcohol on balance ability were investigated in a laboratory setting. The static balance of ten experienced riders was measured while they performed either no secondary task, a visual search task, or a cognitive (arithmetic) task following the administration of alcohol (0; 0.02, and 0.05% BAC). Subjective ratings of intoxication and balance impairment increased in a dose-dependent manner; however, objective measures of static balance were negatively affected only at the .05% BAC dose. Performance on a concurrent secondary visual search task, but not a purely cognitive (arithmetic) task, improved postural stability across all BAC levels. Finally, the .05% BAC dose was associated with impaired performance on the cognitive (arithmetic) task, but not the visual search task, when participants were balancing, but neither task was impaired by alcohol when participants were standing on the floor. Implications for road safety and future ‘drink riding’ policy considerations are discussed.

Efficacy of proxy definitions for identification of fatigue/sleep-related crashes : an Australian evaluation

Fatigue/sleepiness is recognised as an important contributory factor in fatal and serious injury road traffic incidents (RTIs), however, identifying fatigue/sleepiness as a causal factor remains an uncertain science. Within Australia attending police officers at a RTI report the causal factors; one option is fatigue/sleepiness. In some Australian jurisdictions police incident databases are subject to post hoc analysis using a proxy definition for fatigue/sleepiness. This secondary analysis identifies further RTIs caused by fatigue/sleepiness not initially identified by attending officers. The current study investigates the efficacy of such proxy definitions for attributing fatigue/sleepiness as a RTI causal factor. Over 1600 Australian drivers were surveyed regarding their experience and involvement in fatigue/sleep-related RTIs and near-misses during the past five years. Driving while fatigued/sleepy had been experienced by the majority of participants (66.0% of participants). Fatigue/sleep-related near misses were reported by 19.1% of participants, with 2.4% being involved in a fatigue/sleep-related RTI. Examination of the characteristics for the most recent event (either a near miss or crash) found that the largest proportion of incidents (28.0%) occurred when commuting to or from work, followed by social activities (25.1%), holiday travel (19.8%), or for work purposes (10.1%). The fatigue/sleep related RTI and near-miss experience of a representative sample of Australian drivers does not reflect the proxy definitions used for fatigue/sleepiness identification. In particular those RTIs that occur in urban areas and at slow speeds may not be identified. While important to have a strategy for identifying fatigue/sleepiness related RTIs proxy measures appear best suited to identifying specific subsets of such RTIs.

Contracts

Contracting essentially involves an agreement between two parties in relation to a particular matter. When defined in this way, contracting has been occurring as a social practice since humans first bartered and conducted trade, and should be understood as both an economic as well as a social transaction. This entry explains key aspects of the sociology While contracting is commonly understood to be a market based transaction, Polyani famously argued that for most of recorded history commercial transactions were in fact secondary to social relationships. In other words, whenever economic transactions occurred, they were always in the context of reciprocal social relationships. Historically the primary mode of exchange may well have been based on social exchange and reciprocity, however with the rise of extensive industrialization in the 18th Century, the primary mode of exchange has led to more of a market based mode of exchange in developed countries, with the focus more about the economic transaction. As an agreement between two entities, contracting is an essential element to economic systems as it is the basis of most transactions, whether the agreement is verbal or written, explicit or implied. Contracting is thus a pervasive activity in our society, particularly between organizations, although individuals also engage in contracting. Typically, when discussing contracting, authors have either focused on the nature of the agreement itself, or on the governance arrangements in place to carry out the agreement.

Interfacial microstructure in Y1Ba2Cu3O7-δ high Tc superconductors

The microstructures of YBa2Cu3O7-δ ceramics prepared from freeze dried powders and containing an excess of CuO have been studied by analytical electron microscopy. Special attention has been paid to the interfacial microstructure. It was found that a liquid phase formed during sintering between 890°C and 920°C and this promoted grain growth and densification. Both clean grain boundaries and boundaries containing an amorphous intergranular film, which was rich in Cu, have been observed. Both CuO and BaCuO2 were present as secondary phases.

Buzz in motion pictures : what is buzz and how can marketing create it?

In the movie industry, the extraordinarily successful theatrical performance of certain films is largely attributed to buzz. Despite longstanding commentary about the role of buzz in successful movie marketing and the belief that it accelerates new product diffusion, limited scholarly evidence exists to support these assertions. This is primarily due to the lack of conceptual distinction of buzz from word-of-mouth, which is often used as the main basis for conceptualising buzz. However, word-of-mouth does not fully explain the buzz surrounding films such as 'Gone With The Wind', 'The Dark Knight' and 'Avatar'. Informed by valuable insights from key experts who have launched some of the most successful movies in box office history, as well as a range of moviegoers, this thesis developed a deeper understanding of what buzz is and how it is created. This thesis concludes that buzz is not the same as word-of-mouth.

The active site behaviour of electrochemically synthesised gold nanomaterials

Even though gold is the noblest of metals, a weak chemisorber and is regarded as being quite inert, it demonstrates significant electrocatalytic activity in its nanostructured form. It is demonstrated here that nanostructured and even evaporated thin films of gold are covered with active sites which are responsible for such activity. The identification of these sites is demonstrated with conventional electrochemical techniques such as cyclic voltammetry as well as a large amplitude Fourier transformed alternating current (FT-ac) method under acidic and alkaline conditions. The latter technique is beneficial in determining if an electrode process is either Faradaic or capacitive in nature. The observed behaviour is analogous to that observed for activated gold electrodes whose surfaces have been severely disrupted by cathodic polarisation in the hydrogen evolution region. It is shown that significant electrochemical oxidation responses occur at discrete potential values well below that for the formation of the compact monolayer oxide of bulk gold and are attributed to the facile oxidation of surface active sites. Several electrocatalytic reactions are explored in which the onset potential is determined by the presence of such sites on the surface. Significantly, the facile oxidation of active sites is used to drive the electroless deposition of metals such as platinum, palladium and silver from their aqueous salts on the surface of gold nanostructures. The resultant surface decoration of gold with secondary metal nanoparticles not only indicates regions on the surface which are rich in active sites but also provides a method to form interesting bimetallic surfaces.

The modulus of elasticity of steel - is it 200 GPa?

In cold-formed steel construction, the use of a range of thin, high strength steels (0.35 mm thickness and 550 MPa yield stress) has increased significantly in recent times. A good knowledge of the basic mechanical properties of these steels is needed for a satisfactory use of them. In relation to the modulus of elasticity, the current practice is to assume it to be about 200 GPa for all steel grades. However, tensile tests of these steels have consistently shown that the modulus of elasticity varies with grade of steel and thickness. It was found that it increases to values as high as 240 GPa for smaller thicknesses and higher grades of steel. This paper discusses this topic, presents the tensile test results for a number of steel grades and thicknesses, and attempts to develop a relationship between modulus of elasticity, yield stress and thickness for the steel grades considered in this investigation.

Writing the oriental woman : an examination of the representation of Japanese women in contemporary Australian crime fiction

This study considers the challenges in representing women from other cultures in the crime fiction genre. The study is presented in two parts; an exegesis and a creative practice component consisting of a full length crime fiction novel, Batafurai. The exegesis examines the historical period of a section of the novel—post-war Japan—and how the area of research known as Occupation Studies provides an insight into the conditions of women during this period. The exegesis also examines selected postcolonial theory and its exposition of representations of the 'other' as a western construct designed to serve Eurocentric ends. The genre of crime fiction is reviewed, also, to determine how characters purportedly representing Oriental cultures are constricted by established stereotypes. Two case studies are examined to investigate whether these stereotypes are still apparent in contemporary Australian crime fiction. Finally, I discuss my own novel, Batafurai, to review how I represented people of Asian background, and whether my attempts to resist stereotype were successful. My conclusion illustrates how novels written in the crime fiction genre are reliant on strategies that are action-focused, rather than character-based, and thus often use easily recognizable types to quickly establish frameworks for their stories. As a sub-set of popular fiction, crime fiction has a tendency to replicate rather than challenge established stereotypes. Where it does challenge stereotypes, it reflects a territory that popular culture has already visited, such as the 'female', 'black' or 'gay' detective. Crime fiction also has, as one of its central concerns, an interest in examining and reinforcing the notion of societal order. It repeatedly demonstrates that crime either does not pay or should not pay. One of the ways it does this is to contrast what is 'good', known and understood with what is 'bad', unknown, foreign or beyond our normal comprehension. In western culture, the east has traditionally been employed as the site of difference, and has been constantly used as a setting of contrast, excitement or fear. Crime fiction conforms to this pattern, using the east to add a richness and depth to what otherwise might become a 'dry' tale. However, when used in such a way, what is variously eastern, 'other' or Oriental can never be paramount, always falling to secondary side of the binary opposites (good/evil, known/unknown, redeemed/doomed) at work. In an age of globalisation, the challenge for contemporary writers of popular fiction is to be responsive to an audience that demands respect for all cultures. Writers must demonstrate that they are sensitive to such concerns and can skillfully manage the tensions caused by the need to deliver work that operates within the parameters of the genre, and the desire to avoid offence to any cultural or ethnic group. In my work, my strategy to manage these tensions has been to create a back-story for my characters of Asian background, developing them above mere genre types, and to situate them with credibility in time and place through appropriate historical research.

Review: "Breast cancer : can you prevent it?" by A. Lawson, J. Lawson. McGraw-Hill Book (1998)

While reviewing this book, I was not of the target audience. For example, there is a first chapter (presented as a case study, and integrated in an unconvincing manner into the remainder of the book) that obviously meant to soften the book for the lay person. In the third chapter, the authors provide their philosophical interpretation on the meaning of breasts for reasons that entirely escape me, and that have no relation to the book as a whole. Finally, there are potted histories of the heroics of ‘tireless’, ‘dedicated’ and ‘earnest’ epidemiologists, some of whom have nothing to do with breast cancer or the book at all. Despite this lack of focus, the authors give an honest and coherent account of the current state of breast cancer research from an epidemiological viewpoint...

Contemporary comment : is it time for Australia to adopt Circles of Support and Accountability (COSA)?

Circles of Support and Accountability (COSA) - an innovative process for reintegrating child sex offenders into the community after a period of incarceration - have not yet been firmly established in any Australian jurisdiction. This is the case despite their widespread use in Canada, the United Kingdom. and parts of the United States of America, and despite a growing body of research evidence that demonstrates their efficacy in reducing recidivism among child sex offenders. This Contemporary Comment outlines the emergence of COSA and the existing evidence in support of COSA. It argues that COSA should be piloted in Australia.