Segmentation of cone-beam CT using a hidden Markov random field with informative priors

Cone-beam computed tomography (CBCT) has enormous potential to improve the accuracy of treatment delivery in image-guided radiotherapy (IGRT). To assist radiotherapists in interpreting these images, we use a Bayesian statistical model to label each voxel according to its tissue type. The rich sources of prior information in IGRT are incorporated into a hidden Markov random field model of the 3D image lattice. Tissue densities in the reference CT scan are estimated using inverse regression and then rescaled to approximate the corresponding CBCT intensity values. The treatment planning contours are combined with published studies of physiological variability to produce a spatial prior distribution for changes in the size, shape and position of the tumour volume and organs at risk. The voxel labels are estimated using iterated conditional modes. The accuracy of the method has been evaluated using 27 CBCT scans of an electron density phantom. The mean voxel-wise misclassification rate was 6.2\%, with Dice similarity coefficient of 0.73 for liver, muscle, breast and adipose tissue. By incorporating prior information, we are able to successfully segment CBCT images. This could be a viable approach for automated, online image analysis in radiotherapy.

More than merely wicked : regulating sewage discharges and other unspeakable problems in environmental policy-making and planning

While the communicative turn in policy-making has encouraged the public deliberation of policy decisions it has arguably had a more limited impact on the ability of public processes to deal with wicked problems. Wicked policy problems are characterised by high levels of complexity, uncertainty and divergence of values. However, some wicked problems present the additional challenge of high levels of psychosocial sensitivity and verbal proscription. Because these unspeakable policy problems frequently involve a significant moral dimension, the regulation of intimate processes or bodies, and strong elements of abjection and symbolic pollution they are quite literally problems that we don’t like to think about or talk about. However, the potential environmental and social impacts of these problems require that they be addressed. In this paper I present the preliminary findings of a research project focussed on the idea of the unspeakable policy problem and how its unspeakable nature can impact upon public participation and policy and environmental outcomes.

Three-phase model of consumers' behaviours : a synthesis of the theory of planned behaviour, self-determination theory and planning

Using a longitudinal study, an overall behavioural model with three related phases (cognitive, motivational and volitional phase) across three studies was examined to identify the factors that most prominently drive consumer environmental behaviour. This thesis provides empirical evidence to support the behavioural model in an environmental consumption context and shows a new avenue for promoting consumer environmental behaviour.

Planning for sustainability of non motorised public transport in a developing city

Most large cities around the world are undergoing rapid transport sector development to cater for increased urbanization. Subsequently the issues of mobility, access equity, congestion, operational safety and above all environmental sustainability are becoming increasingly crucial in transport planning and policy making. The popular response in addressing these issues has been demand management, through improvement of motorised public transport (MPT) modes (bus, train, tram) and non-motorized transport (NMT) modes (walk, bicycle); improved fuel technology. Relatively little attention has however been given to another readily available and highly sustainable component of the urban transport system, non-motorized public transport (NMPT) such as the pedicab that operates on a commercial basis and serves as an NMT taxi; and has long standing history in many Asian cities; relatively stable in existence in Latin America; and reemerging and expanding in Europe, North America and Australia. Consensus at policy level on the apparent benefits, costs and management approach for NMPT integration has often been a major transport planning problem. Within this context, this research attempts to provide a more complete analysis of the current existence rationale and possible future, or otherwise, of NMPT as a regular public transport system. The analytical process is divided into three major stages. Stage 1 reviews the status and role condition of NMPT as regular public transport on a global scale- in developing cities and developed cities. The review establishes the strong ongoing and future potential role of NMPT in major developing cities. Stage 2 narrows down the status review to a case study city of a developing country in order to facilitate deeper role review and status analysis of the mode. Dhaka, capital city of Bangladesh, has been chosen due to its magnitude of NMPT presence. The review and analysis reveals the multisectoral and dominant role of NMPT in catering for the travel need of Dhaka transport users. The review also indicates ad-hoc, disintegrated policy planning in management of NMPT and the need for a planning framework to facilitate balanced integration between NMPT and MT in future. Stage 3 develops an integrated, multimodal planning framework (IMPF), based on a four-step planning process. This includes defining the purpose and scope of the planning exercise, determining current deficiencies and preferred characteristics for the proposed IMPF, selection of suitable techniques to address the deficiencies and needs of the transport network while laying out the IMPF and finally, development of a delivery plan for the IMPF based on a selected layout technique and integration approach. The output of the exercise is a planning instrument (decision tool) that can be used to assign a road hierarchy in order to allocate appropriate traffic to appropriate network type, particularly to facilitate the operational balance between MT and NMT. The instrument is based on a partial restriction approach of motorised transport (MT) and NMT, structured on the notion of functional hierarchy approach, and distributes/prioritises MT and NMT such that functional needs of the network category is best complemented. The planning instrument based on these processes and principles offers a six-level road hierarchy with a different composition of network-governing attributes and modal priority, for the current Dhaka transport network, in order to facilitate efficient integration of NMT with MT. A case study application of the instrument on a small transport network of Dhaka also demonstrates the utility, flexibility and adoptability of the instrument in logically allocating corridors with particular positions in the road hierarchy paradigm. Although the tool is useful in enabling balanced distribution of NMPT with MT at different network levels, further investigation is required with reference to detailed modal variations, scales and locations of a network to further generalise the framework application.

Imagining in the spatial design process

This thesis aims to expand our understanding of imagining in the spatial design disciplines of architecture and interior design. More than three decades after Lawson’s statement, the matter of “what goes on in a designer’s head”, or imagining and mental problem solving remains just as mysterious and just as pertinent, possibly more so given the social and environmental challenges facing humankind. The lines on a page, the small perspective sketches, the connection of lines and scrawled notes and other clues help us understand what may be going on in the mind of the architect or designer. However, how designers know that space intimately before it is built is not greatly understood and articulated – even by designers themselves. There is a gap in the market in terms of informed exploration of the thinking that occurs during the design process, and how this is translated into physical outcomes. In other words, what do we see in our mind’s eye during the design process? This thesis explores design thinking and design process; what we ‘see’ when we draw, what we ‘see’ when we design.

Incorporating spatial correlations into multispecies mean-field models

In biology, we frequently observe different species existing within the same environment. For example, there are many cell types in a tumour, or different animal species may occupy a given habitat. In modelling interactions between such species, we often make use of the mean field approximation, whereby spatial correlations between the locations of individuals are neglected. Whilst this approximation holds in certain situations, this is not always the case, and care must be taken to ensure the mean field approximation is only used in appropriate settings. In circumstances where the mean field approximation is unsuitable we need to include information on the spatial distributions of individuals, which is not a simple task. In this paper we provide a method that overcomes many of the failures of the mean field approximation for an on-lattice volume-excluding birth-death-movement process with multiple species. We explicitly take into account spatial information on the distribution of individuals by including partial differential equation descriptions of lattice site occupancy correlations. We demonstrate how to derive these equations for the multi-species case, and show results specific to a two-species problem. We compare averaged discrete results to both the mean field approximation and our improved method which incorporates spatial correlations. We note that the mean field approximation fails dramatically in some cases, predicting very different behaviour from that seen upon averaging multiple realisations of the discrete system. In contrast, our improved method provides excellent agreement with the averaged discrete behaviour in all cases, thus providing a more reliable modelling framework. Furthermore, our method is tractable as the resulting partial differential equations can be solved efficiently using standard numerical techniques.

Automated aerial inspection guidance with improved turn planning

Aerial inspection of pipelines, powerlines, and other large linear infrastructure networks has emerged in a number of civilian remote sensing applications. Challenges relate to automating inspection flight for under-actuated aircraft with LiDAR/camera sensor constraints whilst subjected to wind disturbances. This paper presents new improved turn planning strategies with guidance suitable for automation of linear infrastructure inspection able to reduce inspection flight distance by including wind information. Simulation and experimental flight tests confirmed the flight distance saving, and the proposed guidance strategies exhibited good tracking performance in a range of wind conditions.

Engaging young people : reflections from a participatory water planning exercise

While participatory processes have become an important part of water planning, young people are a particularly vulnerable group in terms of potential marginalisation and exclusion from effective participation. Including the views of young people in water planning is not simply a matter of bringing them into existing processes. Instead, processes must be modified to accommodate their needs and ways of expressing their views. Without these adjustments young people may simply move from being kept outside the process to a situation where although they are formally included, their claims are not taken seriously and they are not treated with equal respect. In this paper we reflect on the success of the community advisory committee, formed to develop the Gold Coast Waterfuture Strategy, in integrating the views of young people into their deliberations. Using Young's communicative democracy we highlight the challenges and opportunities presented by this approach, as articulated by both the young people involved and the adult participants, and specifically consider the how the elements of greeting, rhetoric and narrative were reflected in the committee process.

Managing growth in the sunshine states : urbanization and planning in Queensland and Florida

This paper compares the urbanization and planning in the two sunshine states of Florida and Queensland highlighting the similarities and differences, evaluates how effective the growth management programs have been, and examines the recent changes and the challenges they bring to the respective states.

Block models for improved earthwork allocation planning in linear infrastructure construction

Earthwork planning has been considered in this article and a generic block partitioning and modelling approach has been devised to provide strategic plans of various levels of detail. Conceptually this approach is more accurate and comprehensive than others, for instance those that are section based. In response to environmental concerns the metric for decision making was fuel consumption and emissions. Haulage distance and gradient are also included as they are important components of these metrics. Advantageously the fuel consumption metric is generic and captures the physical difficulties of travelling over inclines of different gradients, that is consistent across all hauling vehicles. For validation, the proposed models and techniques have been applied to a real world road project. The numerical investigations have demonstrated that the models can be solved with relatively little CPU time. The proposed block models also result in solutions of superior quality, i.e. they have reduced fuel consumption and cost. Furthermore the plans differ considerably from those based solely upon a distance based metric thus demonstrating a need for industry to reflect upon their current practices.

Agreement between temporal and spatial gait parameters from an instrumented walkway and treadmill system at matched walking speed

Background Commercially available instrumented treadmill systems that provide continuous measures of temporospatial gait parameters have recently become available for clinical gait analysis. This study evaluated the level of agreement between temporospatial gait parameters derived from a new instrumented treadmill, which incorporated a capacitance-based pressure array, with those measured by a conventional instrumented walkway (criterion standard). Methods Temporospatial gait parameters were estimated from 39 healthy adults while walking over an instrumented walkway (GAITRite®) and instrumented treadmill system (Zebris) at matched speed. Differences in temporospatial parameters derived from the two systems were evaluated using repeated measures ANOVA models. Pearson-product-moment correlations were used to investigate relationships between variables measured by each system. Agreement was assessed by calculating the bias and 95% limits of agreement. Results All temporospatial parameters measured via the instrumented walkway were significantly different from those obtained from the instrumented treadmill (P < .01). Temporospatial parameters derived from the two systems were highly correlated (r, 0.79–0.95). The 95% limits of agreement for temporal parameters were typically less than ±2% of gait cycle duration. However, 95% limits of agreement for spatial measures were as much as ±5 cm. Conclusions Differences in temporospatial parameters between systems were small but statistically significant and of similar magnitude to changes reported between shod and unshod gait in healthy young adults. Temporospatial parameters derived from an instrumented treadmill, therefore, are not representative of those obtained from an instrumented walkway and should not be interpreted with reference to literature on overground walking.

Storylines of institutional responses to climate change as a transformative stressor : the case of regional planning in South East Queensland, Australia

Institutional responses to climate change stresses through planning will require new and amended forms of governance. Institutional framing of change imperatives can significantly condition associated governance responses. This paper builds on scholarly conversations concerning the conceptual role of ‘storylines’ in shaping institutional responses to climate change through governance. It draws on conceptual perspectives of climate change as a ‘transformative stressor’, which can compel institutional transformation within planning. The concepts of storylines and transformative stressors are conceptually linked. The conceptual approach is applied to an empirical enquiry focused on the regional planning regime of South East Queensland (SEQ), Australia. This paper reports and examines three institutional storylines of responding to climate change through planning governance in SEQ. It concludes that the manifestation of climate change as a transformative stressor in SEQ prompted institutional transformation, leading to a dominant storyline focused on climate adaptation as an important facet of regional planning governance.

Multiple types of data are required to identify the mechanisms influencing the spatial expansion of melanoma cell colonies

Background The expansion of cell colonies is driven by a delicate balance of several mechanisms including cell motility, cell-to-cell adhesion and cell proliferation. New approaches that can be used to independently identify and quantify the role of each mechanism will help us understand how each mechanism contributes to the expansion process. Standard mathematical modelling approaches to describe such cell colony expansion typically neglect cell-to-cell adhesion, despite the fact that cell-to-cell adhesion is thought to play an important role. Results We use a combined experimental and mathematical modelling approach to determine the cell diffusivity, D, cell-to-cell adhesion strength, q, and cell proliferation rate, ?, in an expanding colony of MM127 melanoma cells. Using a circular barrier assay, we extract several types of experimental data and use a mathematical model to independently estimate D, q and ?. In our first set of experiments, we suppress cell proliferation and analyse three different types of data to estimate D and q. We find that standard types of data, such as the area enclosed by the leading edge of the expanding colony and more detailed cell density profiles throughout the expanding colony, does not provide sufficient information to uniquely identify D and q. We find that additional data relating to the degree of cell-to-cell clustering is required to provide independent estimates of q, and in turn D. In our second set of experiments, where proliferation is not suppressed, we use data describing temporal changes in cell density to determine the cell proliferation rate. In summary, we find that our experiments are best described using the range D = 161 - 243 ?m2 hour-1, q = 0.3 - 0.5 (low to moderate strength) and ? = 0.0305 - 0.0398 hour-1, and with these parameters we can accurately predict the temporal variations in the spatial extent and cell density profile throughout the expanding melanoma cell colony. Conclusions Our systematic approach to identify the cell diffusivity, cell-to-cell adhesion strength and cell proliferation rate highlights the importance of integrating multiple types of data to accurately quantify the factors influencing the spatial expansion of melanoma cell colonies.

On the beach : exploring the complex egalitarianism of the Australian beach

Australia, internationally, is known as a beach loving country, particularly in popular culture. The beach did not figure significantly in academic discussion before the 1980s when Fiske, Hodge, and Turner (1987, 54) researched the beach as a space of myth, seeing it as an integral part of the modern Australian identity. One common myth in Australia is that the beach is an equaliser, a place of multiple ethnicities, shapes, sizes, and genders (Dutton, 1985). I agree that the beach remains a significant aspect of Australian identity; however, limiting its meaning to a mythic space contributing to a homogenous national identity is not adequate. This paper will explore how Australian texts comment on or challenge the myth of the beach as an egalitarian space. I argue that recent Australian texts show a more complex, layered representation of this concept; and that the beach also in this respect can no longer be understood as a myth transcending difference.

The impact of spatial scales and spatial smoothing on the outcome of Bayesian spatial model

Discretization of a geographical region is quite common in spatial analysis. There have been few studies into the impact of different geographical scales on the outcome of spatial models for different spatial patterns. This study aims to investigate the impact of spatial scales and spatial smoothing on the outcomes of modelling spatial point-based data. Given a spatial point-based dataset (such as occurrence of a disease), we study the geographical variation of residual disease risk using regular grid cells. The individual disease risk is modelled using a logistic model with the inclusion of spatially unstructured and/or spatially structured random effects. Three spatial smoothness priors for the spatially structured component are employed in modelling, namely an intrinsic Gaussian Markov random field, a second-order random walk on a lattice, and a Gaussian field with Matern correlation function. We investigate how changes in grid cell size affect model outcomes under different spatial structures and different smoothness priors for the spatial component. A realistic example (the Humberside data) is analyzed and a simulation study is described. Bayesian computation is carried out using an integrated nested Laplace approximation. The results suggest that the performance and predictive capacity of the spatial models improve as the grid cell size decreases for certain spatial structures. It also appears that different spatial smoothness priors should be applied for different patterns of point data.