Approximate Methods For Otherwise Intractable Problems

Recent Monte Carlo methods have expanded the scope of the Bayesian statistical approach. In some situations however, computational methods are often impractically burdensome. We present new methods which reduce this burden and aim to extend the Bayesian toolkit further. This thesis is partitioned into three parts. The first part builds on the Approximate Bayesian Computation (ABC) method. Existing ABC methods often suffer from a local trapping problem which causes inefficient sampling. We present a new ABC framework which overcomes this problem and additionally allows for model selection as a by-product. We demonstrate that this framework conducts ABC inference with an adaptive ABC kernel and extend the framework to specify this kernel in a completely automated way. Furthermore, the ABC part of the thesis also presents a novel methodology for multifidelity ABC. This method constructs a computationally efficient sampler that minimises the approximation error induced by performing early acceptance with a low fidelity model. The second part of the thesis extends the Reversible Jump Monte Carlo method. Reversible Jump methods often suffer from poor mixing. It is possible to construct a “bridge” of intermediate models to facilitate the model transition. However, this scales poorly to big datasets because it requires many evaluations of the model likelihoods. Here we present a new method which greatly improves the scalability at the cost of some approximation error. However, we show that under weak conditions this error is well controlled and convergence is still achieved. The third part of the thesis introduces a multifidelity spatially clustered Gaussian process model. This model enables cheap modelling of nonstationary spatial statistical problems. The model outperforms existing methodology which perform poorly when predicting output at new spatial locations

Public Views About Reintegrating Child Sex Offenders via Circles of Support and Accountability (COSA): A Qualitative Analysis

© 2017 Taylor & Francis Group, LLC. Circles of Support and Accountability (COSA) have recently become part of the criminal justice landscape. However, little has been documented on public views about COSA. The existing research on this topic is entirely quantitative, providing no insight into the reasons behind public support for COSA. This study addresses this gap by analyzing comments made on four online forums following the announcement of Australia’s first COSA program. Findings suggest that community education should focus on a number of key messages about COSA to harness public support for this program. Recommendations are made about the content and delivery of these messages

Community-based approaches to sexual offender reintegration

Perpetration of sexual violence is widespread in Australia, creating long-term negative effects on wellbeing. Community safety is enhanced through reducing the risk of reoffending by those who have sexually offended. A key avenue to reducing risk of reoffending is a community-based program model that aims to reintegrate sexual offenders into the community. Understanding how community-based programs impact recidivism rates is therefore very important. In Australia, few programs that provide this support have been the subject of research. The research project Community-based approaches to sexual offender reintegration looked at two such community-based programs, and documented program characteristics that are key to supporting reintegration and reducing the risk of reoffending

Evidence and Architectural Competency within the Healthcare Procurement Ecosystem

Since the emergence of evidence-based design in the 1990s, much has been written about the role of systematically produced research for improving the quality of healthcare facilities. There has been comparatively little discussion, however, regarding the extent to which evidence may be seen to minimise a range of risks traditionally mitigated through the expertise of the architect. Drawing on our own fieldwork alongside relevant secondary literatures, this paper examines the effects of evidence on perceptions of architectural competency within healthcare procurement. While the availability of design-related evidence was not always observed to alter a design approach it did engender more profound forms of communication between stakeholders, enabling more meaningful interactions between the value orientations those stakeholders represent. In this way, we argue, the emergence of evidence-based design is less a challenge to the professional competency of the architect than a tool for validating this competency, couched in terms that stakeholders from other disciplines customarily recognise

Beyond homeliness: A photo-elicitation study of the ‘homely’ design paradigm in care settings

This paper examines perceptions of homeliness in palliative care environments through a photo-elicitation study involving 89 palliative care staff. The study finds that what is perceived as homely tends to exhibit a mutually exclusive relationship with a clinical antithesis. It also finds that antonymous or antithetical understandings of homeliness are as common as those based on actual attributes of homeliness. It is argued that a more nuanced understanding of the spatial and material constituents of homeliness is needed to make it a more realistic objective within the design and procurement of healthcare environments. It is also argued that the inverse relationship of homely and clinical environmental qualities could be translated into a design approach that aims to negotiate rather than negate their apparent mutual incompatibility

Designing for palliative care: Three ideas toward an architecture of generosity

Palliative care has a distinct philosophy that is not always reflected in the architecture created for it. From a study conducted to better understand the relationship of the built environment to patient and family experiences of palliative care, this article discusses the benefits of access to nature, the provision of semi-private spaces beyond the patient room, and environments that support the rituals of home. Research methods included semi-structured interviews, an online survey, and an architectural precedent study

Of time and tide : the complex impacts of climate change on coastal and underwater cultural heritage

The Intergovernmental Panel on Climate Change has documented wide-ranging changes to the world's coasts and oceans, with significant further change predicted. Impacts on coastal and underwater heritage sites, however, remain relatively poorly understood. The authors draw on 30 years of research into coastal and underwater archaeological sites to highlight some of the interrelated processes of deterioration and damage. Emphasising the need for closer collaboration between, on one hand, archaeologists and cultural resource managers and, on the other, climate and marine scientists, this article also discusses research from other disciplines that informs understanding of the complexity of the interaction of natural and anthropogenic processes and their impacts on cultural heritage.Publisher PDFPeer reviewe

Synthesis and characterisation of biocompatible organic-inorganic core-shell nanocomposite particles based on ureasils.

Organic-inorganic core-shell nanocomposites have attracted increasing attention for applications in imaging, controlled release, biomedical scaffolds and self-healing materials. While tunable properties can readily be achieved through the selection of complementary building blocks, synergistic enhancement requires management of the core-shell interface. In this work, we report a one-pot method to fabricate hybrid core-shell nanocomposite particles (CSNPs) based on ureasils. The native structure of ureasils, which are poly(oxyalkylene)/siloxane hybrids, affords formation of an organic polymer core via nanoprecipitation, while the terminal siloxane groups act as a template for nucleation and growth of the silica shell via the Stöber process. Through optimisation of the reaction conditions, we demonstrate the reproducible synthesis of ureasil CSNPs, with a hydrodynamic diameter of ∼150 nm and polydispersity 50 days. Selective functionalisation, either through the physical entrapment of polarity-sensitive fluorescent probes (coumarin 153, pyrene) or covalent-grafting to the silica shell (fluorescein isothiocyanate) is also demonstrated and provides insight into the internal environment of the particles. Moreover, preliminary studies using a live/dead cell assay indicate that ureasil CSNPs do not display cytotoxicity. Given the simple fabrication method and the structural tunability and biocompatability of the ureasils, this approach presents an efficient route to multifunctional core-shell nanocomposite particles whose properties may be tailored for a targeted application

Emerging organic contaminants in the river Ganga and key tributaries in the middle Gangetic Plain, India:Characterization, distribution & controls

The presence and distribution of emerging organic contaminants (EOCs) in freshwater environments is a key issue in India and globally, particularly due to ecotoxicological and potential antimicrobial resistance concerns. Here we have investigated the composition and spatial distribution of EOCs in surface water along a ∼500 km segment of the iconic River Ganges (Ganga) and key tributaries in the middle Gangetic Plain of Northern India. Using a broad screening approach, in 11 surface water samples, we identified 51 EOCs, comprising of pharmaceuticals, agrochemicals, lifestyle and industrial chemicals. Whilst the majority of EOCs detected were a mixture of pharmaceuticals and agrochemicals, lifestyle chemicals (and particularly sucralose) occurred at the highest concentrations. Ten of the EOCs detected are priority compounds (e.g. sulfamethoxazole, diuron, atrazine, chlorpyrifos, perfluorooctane sulfonate (PFOS), perfluorobutane sulfonate, thiamethoxam, imidacloprid, clothianidin and diclofenac). In almost 50% of water samples, sulfamethoxazole concentrations exceeded predicted no-effect concentrations (PNECs) for ecological toxicity. A significant downstream reduction in EOCs was observed along the River Ganga between Varanasi (Uttar Pradesh) and Begusarai (Bihar), likely reflecting dilution effects associated with three major tributaries, all with considerably lower EOC concentrations than the main Ganga channel. Sorption and/or redox controls were observed for some compounds (e.g. clopidol), as well as a relatively high degree of mixing of EOCs within the river. We discuss the environmental relevance of the persistence of several parent compounds (notably atrazine, carbamazepine, metribuzin and fipronil) and associated transformation products. Associations between EOCs and other hydrochemical parameters including excitation emission matrix (EEM) fluorescence indicated positive, significant, and compound-specific correlations between EOCs and tryptophan-, fulvic- and humic-like fluorescence. This study expands the baseline characterization of EOCs in Indian surface water and contributes to an improved understanding of the potential sources and controls on EOC distribution in the River Ganga and other large river systems