Inferring kangaroo phylogeny from incongruent nuclear and mitochondrial genes

The marsupial genus Macropus includes three subgenera, the familiar large grazing kangaroos and wallaroos of M. (Macropus) and M. (Osphranter), as well as the smaller mixed grazing/browsing wallabies of M. (Notamacropus). A recent study of five concatenated nuclear genes recommended subsuming the predominantly browsing Wallabia bicolor (swamp wallaby) into Macropus. To further examine this proposal we sequenced partial mitochondrial genomes for kangaroos and wallabies. These sequences strongly favour the morphological placement of W. bicolor as sister to Macropus, although place M. irma (black-gloved wallaby) within M. (Osphranter) rather than as expected, with M. (Notamacropus). Species tree estimation from separately analysed mitochondrial and nuclear genes favours retaining Macropus and Wallabia as separate genera. A simulation study finds that incomplete lineage sorting among nuclear genes is a plausible explanation for incongruence with the mitochondrial placement of W. bicolor, while mitochondrial introgression from a wallaroo into M. irma is the deepest such event identified in marsupials. Similar such coalescent simulations for interpreting gene tree conflicts will increase in both relevance and statistical power as species-level phylogenetics enters the genomic age. Ecological considerations in turn, hint at a role for selection in accelerating the fixation of introgressed or incompletely sorted loci. More generally the inclusion of the mitochondrial sequences substantially enhanced phylogenetic resolution. However, we caution that the evolutionary dynamics that enhance mitochondria as speciation indicators in the presence of incomplete lineage sorting may also render them especially susceptible to introgression.

Steps toward the validation of the Trendelenburg Test : the effect of experimentally reduced hip abductor muscle function on frontal plane mechanics

Objective: To investigate the validity of the Trendelenburg test (TT) using an ultrasound-guided nerve block (UNB) of the superior gluteal nerve and determine whether the reduction in hip abductor muscle (HABD) strength would result in the theorized mechanical compensatory strategies measured during the TT. Design: Quasi-experimental. Setting: Hospital. Participants: Convenience sample of 9 healthy men. Only participants with no current or previous injury to the lumbar spine, pelvis, or lower extremities, and no previous surgeries were included. Interventions: Ultrasound-guided nerve block. Main Outcome Measures: Hip abductor muscle strength (percent body weight [%BW]), contralateral pelvic drop (cPD), change in contralateral pelvic drop (Delta cPD), ipsilateral hip adduction, and ipsilateral trunk sway (TRUNK) measured in degrees. Results: The median age and weight of the participants were 31 years (interquartile range [IQR], 22-32 years) and 73 kg (IQR, 67-81 kg), respectively. An average 52% reduction of HABD strength (z = 2.36, P = 0.02) resulted after the UNB. No differences were found in cPD or Delta cPD (z = 0.01, P = 0.99, z = 20.67, P = 0.49, respectively). Individual changes in biomechanics showed no consistency between participants and nonsystematic changes across the group. One participant demonstrated the mechanical compensations described by Trendelenburg. Conclusions: The TT should not be used as a screening measure for HABD strength in populations demonstrating strength greater than 30% BW but should be reserved for use with populations with marked HABD weakness. Clinical Relevance: This study presents data regarding a critical level of HABD strength required to support the pelvis during the TT.

The relationship between hip abductor muscle strength and magnitude of pelvic drop following a 3 week strengthening protocol in non-specific low back pain patients.

Purpose: To examine the relationship between hip abductor muscle (HABD) strength and the magnitude of pelvic drop (MPD) for patients with non-specific low back pain (NSLBP) and controls (CON) prior to and following a 3-week HABD strengthening protocol. At baseline, we hypothesized that NSLBP patients would exhibit reduced HABD strength and greater MPD compared to CON. Following the protocol, we hypothesized that strength would increase and MPD would decrease. Relevance: The Trendelenburg test (TT) is a common clinical test used to examine the ability of the HABD to maintain horizontal pelvic position during single limb stance. However, no study has specifically tested this theory. Moreover, no study has investigated the relationship between HABD strength and pelvic motion during walking or tested whether increased HABD strength would reduce the MPD. Methods: Quasi-experimental with 3-week exercise intervention. Fifteen NSLBP patients (32.5yrs,range 21-51yrs; VAS baseline: 5.3cm) and 10 CON (29.5yrs,range 22-47yrs) were recruited. Isometric HABD strength was measured using a force dynamometer and the average of three maximal voluntary contractions were normalized to body mass (N/kg). Two-dimensional MPD (degrees) was measured using a 60 Hz camera and was derived from two retroreflective-markers placed on the posterior superior iliac spines. MPD was measured while performing the static TT and while walking and averaged over 10 consecutive footfalls. NSLBP patients completed a 3-week HABD strengthening protocol consisting of 2 open-kinetic-chain exercises then all measures were repeated. Non-parametric analysis was used for group comparisons and correlation analysis. Results: At baseline, the NSLBP patients demonstrated 31% reduced HABD strength (mean=6.6 N/kg) compared to CON (mean=9.5 N/kg: p=0.03) and no significant differences in maximal pelvic frontal plane excursion while walking (NSLBP:mean=8.1°, CON:mean=7.1°: p=0.72). No significant correlations were measured between left HABD strength and right MPD (r=-0.37, p=0.11), or between right HABD strength and left MPD (r=-0.04, p=0.84) while performing the static TT. Following the 3-week strengthening protocol, NSLBP patients demonstrated a 12% improvement in strength (Post:mean=7.4 N/kg: p=0.02), a reduction in pain (VAS followup: 2.8cm), but no significant decreases in MPD while walking (p=0.92). Conclusions: NSLBP patients demonstrated reduced HABD strength at baseline and were able to increase strength and reduce pain in a 3-week period. However, despite increases in HABD strength, the NSLBP group exhibited similar MPD motion during the static TT and while walking compared to baseline and controls. Implications: The results suggest that the HABD alone may not be primarily responsible for controlling a horizontal pelvic position during static and dynamic conditions. Increasing the strength of the hip abductors resulted in a reduction of pain in NSLBP patients providing evidence for further research to identify specific musculature responsible for controlling pelvic motion.

The diversity of interests in environmental governance : a challenge for the rule of law

The function of environmental governance and the principle of the rule of law are both controversial and challenging. To apply the principle of the rule of law to the function of environmental governance is perhaps even more controversial and challenging. A system of environmental governance seeks to bring together the range of competitive and potentially conflicting interests in how the environment and its resources are managed. Increasingly it is the need for economic, social and ecological sustainability that brings these interests – both public and private – together. Then there is the relevance of the principle of the rule of law. Economic, social and ecological sustainability will be achieved – if at all – by a complex series of rules of law that are capable of enforcement so as to ensure compliance with them. To what extent do these rules of law reflect the principle of the rule of law? Is the principle of the rule of law the formally unstated value that is expected to underpin the legal system or is it the normative predicate that directs the legal system both vertically and horizontally? Is sustainability an aspirational value or a normative predicate according to which the environment and its resources are managed? Let us deal sequentially with these issues by reviewing a number of examples that demonstrate the relationship between environmental governance and the rule of law.

Public health psychology : a conceptual and practical framework

Increasingly, the development of public health infrastructures requires psychology to reevaluate its contribution to public health at local, national and global levels. Already familiar to some psychologists, particularly those in community psychology and health promotion, the expansion of public health has implications for psychology in terms of knowledge/practice and working differently in multidisciplinary settings. In this article, I provide a critical overview of the implications of the historical and international development of health psychology and the changing nature of public health to strengthen the establishment of public health psychology. A conceptual and practical framework is proposed in which public health psychology theory, methods and practice are considered as well as its relevance to the health social sciences more generally.

Phylodynamic analysis of the emergence and epidemiological impact of transmissible defective dengue viruses

Intra-host sequence data from RNA viruses have revealed the ubiquity of defective viruses in natural viral populations, sometimes at surprisingly high frequency. Although defective viruses have long been known to laboratory virologists, their relevance in clinical and epidemiological settings has not been established. The discovery of long-term transmission of a defective lineage of dengue virus type 1 (DENV-1) in Myanmar, first seen in 2001, raised important questions about the emergence of transmissible defective viruses and their role in viral epidemiology. By combining phylogenetic analyses and dynamical modelling, we investigate how evolutionary and ecological processes at the intra-host and inter-host scales shaped the emergence and spread of the defective DENV-1 lineage. We show that this lineage of defective viruses emerged between June 1998 and February 2001, and that the defective virus was transmitted primarily through co-transmission with the functional virus to uninfected individuals. We provide evidence that, surprisingly, this co-transmission route has a higher transmission potential than transmission of functional dengue viruses alone. Consequently, we predict that the defective lineage should increase overall incidence of dengue infection, which could account for the historically high dengue incidence reported in Myanmar in 2001-2002. Our results show the unappreciated potential for defective viruses to impact the epidemiology of human pathogens, possibly by modifying the virulence-transmissibility trade-off, or to emerge as circulating infections in their own right. They also demonstrate that interactions between viral variants, such as complementation, can open new pathways to viral emergence.

Land use planning and the airport metropolis

Australian airports have emerged as important urban activity centres over the past decade as a result of privatisation. A range of reciprocal airport and regional impacts now pose considerable challenges for both airport operation and the surrounding urban and regional environment. The airport can no longer be managed solely as a specialised transport entity in isolation from the metropolis that it serves. In 2007 a multidisciplinary Australian Research Council Linkage Project (LP 0775225) was funded to investigate the changing role of airports in Australia. This thesis is but one component of this collaborative research effort. Here the issues surrounding the policy and practice of airport and regional land use planning are explored, analysed and detailed. This research, for the first time, assembles a distinct progression of the wider social, economic, technological and environmental roles of the airport within the Australian airport literature from 1914 – 2011. It recognises that while the list of airport and regional impacts has grown through time, treatment within practice and the literature has largely remained highly specialised and contained within disciplinary paradigms. The first publication of the thesis (Chapter 2) acknowledges that the changing role of airports demands the establishment of new models of airport planning and development. It argues that practice and research requires a better understanding of the reciprocal impacts of airports and their urban catchments. The second publication (Chapter 3) highlights that there is ad hoc examination and media attention of high profile airport and regional conflict, but little empirical analysis or understanding of the extent to which all privatised Australian airports are intending to develop. The conceptual and methodological significance of this research is the development of a national land use classification system for on-airport development. This paper establishes the extent of on-airport development in Australia, providing insight into the changing land use and economic roles of privatised airports. The third publication (Chapter 4) details new and significant interdependencies for airport and regional development in consideration of the progression of airports as activity centres. Here the model of an ‘airport metropolis’ is offered as an organising device and theoretical contribution for comprehending the complexity and planning of airport and regional development. It delivers a conceptual framework for both research and policy, which acknowledges the reciprocal impacts of economic development, land use, infrastructure and governance ‘interfaces’. In a timely and significant concurrence with this research the Australian Government announced and delivered a National Aviation Policy Review (2008 – 2009). As such the fourth publication (Chapter 5) focuses on the airport and urban planning aspects of the review. This paper also highlights the overall policy intention of facilitating broader airport and regional collaborative processes. This communicative turn in airport policy is significant in light of the communicative theoretical framework of the thesis. The fifth paper of the thesis (Chapter 6) examines three Australian case studies (Brisbane, Adelaide and Canberra) to detail the context of airport and regional land use planning and to apply the airport metropolis model as a framework for research. Through the use of Land Use Forums, over 120 airport and regional stakeholders are brought together to detail their perspectives and interactions with airport and regional land use planning. An inductive thematic analysis of the results identifies three significant themes which contribute to the fragmentation of airport and regional and land use planning: 1) inadequate coordination and disjointed decision-making; 2) current legislative and policy frameworks; and 3) competing stakeholder priorities and interests. Building on this new knowledge, Chapter 7 details the perceptions of airport and local, state and territory government stakeholders to land use relationships, processes and outcomes. A series of semi-structured interviews are undertaken in each of the case studies to inform this research. The potential implications for ongoing communicative practice are discussed in conclusion. The following thesis represents an incremental and cumulative research process which delivers new knowledge for the practical understanding and research interpretation of airport and regional land use planning practice and policy. It has developed and applied a robust conceptual framework which delivers significant direction for all stakeholders to better comprehend the relevance of airports in the urban character and design of our cities.

Background to the development of a curriculum for the history of “cyber” and “communications” security

For any discipline to be regarded as a professional undertaking by which its members may be treated as true “professionals” in a specific area, practitioners must clearly understand that discipline’s history as well as the place and significance of that history in current practice as well as its relevance to available technologies and artefacts at the time. This is common for many professional disciplines such as medicine, pharmacy, engineering, law and so on but not yet, this paper submits, in information technology. Based on twenty five elapsed years of experience in developing and delivering Cybersecurity courses at undergraduate and postgraduate levels, this paper proposes a rationale and set of differing perspectives for the planning and development of curricula relevant to the delivery of appropriate courses in the history of cybersecurity or information assurance to information and communications technology (ICT) students and thus to potential information technology professionals.

[Book Review] Urban Maps : Instruments of Narrative and Interpretation in the City by Richard Brook and Nick Dunn, Ashgate, Farham, United Kingdom, 2011, 250pp. ISBN 978-0-754676-5-77.

Urban maps discusses new ways and tools to read and navigate the contemporary city. Each chapter investigates a possible approach to unravel the complexity of contemporary urban forms. Each tool is first defined, introducing its philosophical background, and is then discussed with case studies, showing its relevance for the navigation of the built environment. Urbanism classics such as the work of Lynch, Jacobs, Venuti and Scott-Brown, Lefebrve and Walter Benjamin are fundamental in setting the framework of the volume. In the introduction cities and mapping are first discussed, the former are illustrated as ‘a composite of invisible networks devoid of landmarks and overrun by nodes’ (p. 3), and ‘a series of unbounded spaces where mass production and mass consumption reproduce a standardised quasi-global culture’ (p. 6).

Academic success in context-based chemistry : Demonstrating fluid transitions between concepts and context

Curriculum developers and researchers have promoted context-based programmes to arrest waning student interest and participation in the enabling sciences at high school and university. Context-based programmes aim for student connections between scientific discourse and real-world contexts to elevate curricular relevance without diminishing conceptual understanding. This interpretive study explored the learning transactions in one 11th grade context-based chemistry classroom where the context was the local creek. The dialectic of agency/structure was used as a lens to examine how the practices in classroom interactions afforded students the agency for learning. The results suggest that first, fluid transitions were evident in the student–student interactions involving successful students; and second, fluid transitions linking concepts to context were evident in the students’ successful reports. The study reveals that the structures of writing and collaborating in groups enabled students’ agential and fluent movement between the field of the real-world creek and the field of the formal chemistry classroom. Furthermore, characteristics of academically successful students in context-based chemistry are highlighted. Research, teaching, and future directions for context-based science teaching are discussed.

Comprehensive assessment of the fitness of older people for chemotherapy

Purpose: To present the results of a mixed-method study comparing the level of agreement of a two-phased, nurse-administered Comprehensive Geriatric Assessment (CGA) with current methods that assess the fitness for chemotherapy of older cancer patients. A nurse-led model of multidisciplinary cancer care based on the results is also described. Methods: The two phases comprised initial screening by a nurse with the Vulnerable Elders Survey-13 [VES-13], followed by nurse administration of a detailed CGA. Both phases were linked to a computerised algorithm categorising the patient as ‘fit’, ‘vulnerable’ or ‘frail’. The study determined the level of agreement between VES-13- and CGA-determined categories; and between the CGA and the physicians’ assessments. It also compared the CGA’s predictive abilities in terms of subsequent treatment toxicity; while interviews determined the acceptability of the nurse-led procedure from key stakeholders' perspectives. Results: Data collection was completed in December 2011. The results will be presented at the conference. A consecutive-series n=170 will be enrolled, 33% of whom are ‘fit’; 33% ‘vulnerable’; and 33% ‘too frail’ for treatment. This sample can detect, with 90% power, kappa coefficients of agreement of ≥ 0.70 or higher (“substantial agreement”). Fitness sub-group comparisons of agreement between the medical oncologist and the nurse assessments can detect kappa estimates of Κ ≥ 0.80 with the same power. Conclusion: The results have informed a nurse-led model of cancer care. It meets a clear need to develop, implement and test a nurse-led, robust, evidence-based, clinically-justifiable and economically-feasible CGA process that has relevance in national and international contexts.

Protein markers for Alzheimer disease in the frontal cortex and cerebellum

Objective: To compare proteins related to Alzheimer disease ( AD) in the frontal cortex and cerebellum of subjects with early-onset AD (EOAD) with or without presenilin 1 (PS1) mutations with sporadic late-onset AD ( LOAD) and nondemented control subjects. Methods: Immunohistochemistry, immunoblot analysis, and ELISA were used to detect and assess protein levels in brain. Results: In EOAD and to a lesser extent in LOAD, there was increased amyloid beta (Abeta) deposition (by immunohistochemistry), increased soluble Abeta (by immunoblot analysis), and specific increases in Abeta(40) and Abeta(42) ( by ELISA) in the frontal cortex and, in some cases, in the cerebellum. Surprisingly, immunoblot analysis revealed reduced levels of PS1 in many of the subjects with EOAD with or without PS1 mutations. In those PS1 mutation-bearing subjects with the highest Abeta, PS1 was barely, if at all, detectable. This decrease in PS1 was specific and not attributable solely to neuronal loss because amyloid precursor protein (APP) and the PS1-interacting protein beta-catenin levels were unchanged. Conclusions: This study shows that in the frontal cortex and cerebellum from Alzheimer disease patients harboring certain presenilin 1 mutations, high levels of amyloid beta are associated with low levels of presenilin 1. The study provides the premise for further investigation of mechanisms underlying the downregulation of presenilin 1, which may have considerable pathogenic and therapeutic relevance.

Establishment and characterisation of an open mini-thoracotomy surgical approach to an ovine thoracic spine fusion model

Background A large animal model is required for assessment of minimally invasive, tissue engineering based approaches to thoracic spine fusion, with relevance to deformity correction surgery for human adolescent idiopathic scoliosis. Here we develop a novel open mini–thoracotomy approach in an ovine model of thoracic interbody fusion which allows assessment of various fusion constructs, with a focus on novel, tissue engineering based interventions. Methods The open mini-thoracotomy surgical approach was developed through a series of mock surgeries, and then applied in a live sheep study. Customized scaffolds were manufactured to conform with intervertebral disc space clearances required of the study. Twelve male Merino sheep aged 4 to 6 years and weighing 35 – 45 kg underwent the abovementioned procedure and were divided into two groups of six sheep at survival timelines of 6 and 12 months. Each sheep underwent a 3-level discectomy (T6/7, T8/9 and T10/11) with randomly allocated implantation of a different graft substitute at each of the three levels; (i) polycaprolactone (PCL) based scaffold plus 0.54μg rhBMP-2, (ii) PCL-based scaffold alone or (iii) autograft. The sheep were closely monitored post- operatively for signs of pain (i.e. gait abnormalities/ teeth gnawing/ social isolation). Fusion assessments were conducted post-sacrifice using Computed Tomography and hard-tissue histology. All scientific work was undertaken in accordance with the study protocol has been approved by the Institute's committee on animal research. Results. All twelve sheep were successfully operated on and reached the allotted survival timelines, thereby demonstrating the feasibility of the surgical procedure and post-operative care. There were no significant complications and during the post-operative period the animals did not exhibit marked signs of distress according to the described assessment criteria. Computed Tomographic scanning demonstrated higher fusion grades in the rhBMP-2 plus PCL-based scaffold group in comparison to either PCL-based scaffold alone or autograft. These results were supported by histological evaluation of the respective groups. Conclusion. This novel open mini-thoracotomy surgical approach to the ovine thoracic spine represents a safe surgical method which can reproducibly form the platform for research into various spine tissue engineered constructs (TEC) and their fusion promoting properties.

Biological performance of a polycaprolactone-based scaffold plus recombinant human morphogenetic protein-2 (rhBMP-2) in an ovine thoracic interbody fusion model

Introduction. We develop a sheep thoracic spine interbody fusion model to study the suitability of polycaprolactone-based scaffold and recombinant human bone morphogenetic protein-2 (rhBMP-2) as a bone graft substitute within the thoracic spine. The surgical approach is a mini- open thoracotomy with relevance to minimally invasive deformity correction surgery for adolescent idiopathic scoliosis. To date there are no studies examining the use of this biodegradable implant in combination with biologics in a sheep thoracic spine model. Methods. In the present study, six sheep underwent a 3-level (T6/7, T8/9 and T10/11) discectomy with randomly allocated implantation of a different graft substitute at each of the three levels; (i) calcium phosphate (CaP) coated polycaprolactone based scaffold plus 0.54µg rhBMP-2, (ii) CaP coated PCL- based scaffold alone or (iii) autograft (mulched rib head). Fusion was assessed at six months post-surgery. Results. Computed Tomographic scanning demonstrated higher fusion grades in the rhBMP-2 plus PCL- based scaffold group in comparison to either PCL-based scaffold alone or autograft. These results were supported by histological evaluations of the respective groups. Biomechanical testing revealed significantly higher stiffness for the rhBMP-2 plus PCL- based scaffold group in all loading directions in comparison to the other two groups. Conclusions. The results of this study demonstrate that rhBMP-2 plus PCL-based scaffold is a viable bone graft substitute, providing an optimal environment for thoracic interbody spinal fusion in a large animal model.

The contribution of psychosocial factors to socioeconomic differences in food purchasing

In developed countries the relationship between socioeconomic position (SEP) and health is unequivocal. Those who are socioeconomically disadvantaged are known to experience higher morbidity and mortality from a range of chronic diet-related conditions compared to those of higher SEP. Socioeconomic inequalities in diet are well established. Compared to their more advantaged counterparts, those of low SEP are consistently found to consume diets less consistent with dietary guidelines (i.e. higher in fat, salt and sugar and lower in fibre, fruit and vegetables). Although the reasons for dietary inequalities remain unclear, understanding how such differences arise is important for the development of strategies to reduce health inequalities. Both environmental (e.g. proximity of supermarkets, price, and availability of foods) and psychosocial (e.g. taste preference, nutrition knowledge) influences are proposed to account for inequalities in food choices. Although in the United States (US), United Kingdom (UK), and parts of Australia, environmental factors are associated with socioeconomic differences in food choices, these factors do not completely account for the observed inequalities. Internationally, this context has prompted calls for further exploration of the role of psychological and social factors in relation to inequalities in food choices. It is this task that forms the primary goal of this PhD research. In the small body of research examining the contribution of psychosocial factors to inequalities in food choices, studies have focussed on food cost concerns, nutrition knowledge or health concerns. These factors are generally found to be influential. However, since a range of psychosocial factors are known determinants of food choices in the general population, it is likely that a range of factors also contribute to inequalities in food choices. Identification of additional psychosocial factors of relevance to inequalities in food choices would provide new opportunities for health promotion, including the adaption of existing strategies. The methodological features of previous research have also hindered the advancement of knowledge in this area and a lack of qualitative studies has resulted in a dearth of descriptive information on this topic. This PhD investigation extends previous research by assessing a range of psychosocial factors in relation to inequalities in food choices using both quantitative and qualitative techniques. Secondary data analyses were undertaken using data obtained from two Brisbane-based studies, the Brisbane Food Study (N=1003, conducted in 2000), and the Sixty Families Study (N=60, conducted in 1998). Both studies involved main household food purchasers completing an interviewer-administered survey within their own home. Data pertaining to food-purchasing, and psychosocial, socioeconomic and demographic characteristics were collected in each study. The mutual goals of both the qualitative and quantitative phases of this investigation were to assess socioeconomic differences in food purchasing and to identify psychosocial factors relevant to any observed differences. The quantitative methods then additionally considered whether the associations examined differed according to the socioeconomic indicator used (i.e. income or education). The qualitative analyses made a unique contribution to this project by generating detailed descriptions of socioeconomic differences in psychosocial factors. Those with lower levels of income and education were found to make food purchasing choices less consistent with dietary guidelines compared to those of high SEP. The psychosocial factors identified as relevant to food-purchasing inequalities were: taste preferences, health concerns, health beliefs, nutrition knowledge, nutrition concerns, weight concerns, nutrition label use, and several other values and beliefs unique to particular socioeconomic groups. Factors more tenuously or inconsistently related to socioeconomic differences in food purchasing were cost concerns, and perceived adequacy of the family diet. Evidence was displayed in both the quantitative and qualitative analyses to suggest that psychosocial factors contribute to inequalities in food purchasing in a collective manner. The quantitative analyses revealed that considerable overlap in the socioeconomic variation in food purchasing was accounted for by key psychosocial factors of importance, including taste preference, nutrition concerns, nutrition knowledge, and health concerns. Consistent with these findings, the qualitative transcripts demonstrated the interplay between such influential psychosocial factors in determining food-purchasing choices. The qualitative analyses found socioeconomic differences in the prioritisation of psychosocial factors in relation to food choices. This is suggestive of complex cultural factors that distinguish advantaged and disadvantaged groups and result in socioeconomically distinct schemas related to health and food choices. Compared to those of high SEP, those of lower SEP were less likely to indicate that health concerns, nutrition concerns, or food labels influenced food choices, and exhibited lower levels of nutrition knowledge. In the absence of health or nutrition-related concerns, taste preferences tended to dominate the food purchasing choices of those of low SEP. Overall, while cost concerns did not appear to be a main determinant of socioeconomic differences in food purchasing, this factor had a dominant influence on the food choices of some of the most disadvantaged respondents included in this research. The findings of this study have several implications for health promotion. The integrated operation of psychosocial factors on food purchasing inequalities indicates that multiple psychosocial factors may be appropriate to target in health promotion. It also seems possible that the inter-relatedness of psychosocial factors would allow health promotion targeting a single psychosocial factor to have a flow-on affect in terms of altering other influential psychosocial factors. This research also suggests that current mass marketing approaches to health promotion may not be effective across all socioeconomic groups due to differences in the priorities and main factors of influence in food purchasing decisions across groups. In addition to the practical recommendations for health promotion, this investigation, through the critique of previous research, and through the substantive study findings, has highlighted important methodological considerations for future research. Of particular note are the recommendations pertaining to the selection of socioeconomic indicators, measurement of relevant constructs, consideration of confounders, and development of an analytical approach. Addressing inequalities in health has been noted as a main objective by many health authorities and governments internationally. It is envisaged that the substantive and methodological findings of this thesis will make a useful contribution towards this important goal.