Drug diffusion from polymeric delivery devices : a problem with two moving boundaries

An existing model for solvent penetration and drug release from a spherically-shaped polymeric drug delivery device is revisited. The model has two moving boundaries, one that describes the interface between the glassy and rubbery states of polymer, and another that defines the interface between the polymer ball and the pool of solvent. The model is extended so that the nonlinear diffusion coefficient of drug explicitly depends on the concentration of solvent, and the resulting equations are solved numerically using a front-fixing transformation together with a finite difference spatial discretisation and the method of lines. We present evidence that our scheme is much more accurate than a previous scheme. Asymptotic results in the small-time limit are presented, which show how the use of a kinetic law as a boundary condition on the innermost moving boundary dictates qualitative behaviour, the scalings being very different to the similar moving boundary problem that arises from modelling the melting of an ice ball. The implication is that the model considered here exhibits what is referred to as ``non-Fickian'' or Case II diffusion which, together with the initially constant rate of drug release, has certain appeal from a pharmaceutical perspective.

Re-imagining static Utopias : unraveling the bat/human problem

The making of the modern world has long been fuelled by utopian images that are blind to ecological reality. Botanical gardens are but one example – who typically portray themselves as miniature, isolated 'edens on earth'. Whilst respected, heritage-laden institutions such as the Royal Botanical Gardens in Sydney, Australia promote such an idealised image they are now self-evidently also the vital ‘lungs’ of a crowded city as well as a critical habitats for threatened biodiversity (in this case notably flying foxes). In 2010 the 'Remnant Emergency Artlab' set out to alleviate this utopian hangover through a creative provocation called the 'Botanical Gardens ‘X-Tension’ - an imagined city-wide, distributed, network of 'ecological gardens' - in order to ask, what now needs to be better understood, connected and therefore ultimately conserved?

Heidegger's hippies : a dissenting voice on "the problem of the subject"

This is a deliberately contentious paper about the future of the socio-political sphere in the West based on what we know about its past. I argue that the predominant public discourse in Western countries is best characterised as one of selective forgetfulness; a semi-blissful, amnesiacal state of collective dementia that manifests itself in symbolic idealism: informationalism. Informationalism is merely the latest form of idealism. It is a lot like religion insofar as it causally relates abstract concepts with reality and, consequently, becomes confused between the two. Historically, this has proven to be a dangerous state of affairs, especially when elites becomes confused between ideas about how a society should work, and the way it actually does work. Central to the idealism of the information age, at least in intellectual spheres, is the so called "problem of the subject". I argue that the "problem of the subject" is a largely synthetic, destabilising, and ultimately fruitless theoretical abstraction which turns on a synthetically derived, generalised intradiscursive space; existentialist nihilism; and the theoretical baubles of ontological metaphysics. These philosophical aberrations are, in turn, historically concomitant with especially destructive political and social configurations. This paper sketches a theoretical framework for identity formation which rejects the problem of the subject, and proposes potential resources, sources, and strategies with which to engage the idealism that underpins this obfuscating problematic in an age of turbulent social uncertainty. Quite simply, I turn to history as the source of human identity. While informationalism, like religion, is mostly focused on utopian futures, I assert that history, not the future, holds the solutions for substantive problematics concerning individual and social identities. I argue here that history, language, thought, and identity are indissolubly entangled and so should be understood as such: they are the fundamental parts of 'identities in action'. From this perspective, the ‘problem of the subject’ becomes less a substantive intellectual problematic and more a theoretical red herring.

Understanding the role of knowledge in the practice of expert nephrology nurses in Australia

This paper, which is abstracted from a larger study into the acquisition and exercise of nephrology nursing expertise, aims to explore the role of knowledge in expert practice. Using grounded theory methodology, the study involved 17 registered nurses who were practicing in a metropolitan renal unit in New South Wales, Australia. Concurrent data collection and analysis was undertaken, incorporating participants' observations and interviews. Having extensive nephrology nursing knowledge was a striking characteristic of a nursing expert. Expert nurses clearly relied on and utilized extensive nephrology nursing knowledge to practice. Of importance for nursing, the results of this study indicate that domain-specific knowledge is a crucial feature of expert practice.

A proactive response to the mobbing problem : a guide for HR managers

This paper introduces the concept of workplace mobbing as a destructive organizational behaviour of psychological assaults perpetrated against the target causing them harm and loss of employment. The discussion is drawn from a three year Australian study of 212 self identified targets of workplace mobbing behaviours. The behaviours are typically covert with informal networks and friendship loyalties providing effective mechanisms for emotional abuse, including those arising from human resource management practices. This paper discusses the manipulation of informal sources of power, with the use of gossip, rumour, hearsay, and innuendo to discredit and demonise those targeted. The study explores some of the systemic reasons for these behaviours and identifies some of the contributing risk factors and suggests management practices that can minimise the harm caused.

The sample complexity of pattern classification with neural networks: the size of the weights is more important than the size of the network

Sample complexity results from computational learning theory, when applied to neural network learning for pattern classification problems, suggest that for good generalization performance the number of training examples should grow at least linearly with the number of adjustable parameters in the network. Results in this paper show that if a large neural network is used for a pattern classification problem and the learning algorithm finds a network with small weights that has small squared error on the training patterns, then the generalization performance depends on the size of the weights rather than the number of weights. For example, consider a two-layer feedforward network of sigmoid units, in which the sum of the magnitudes of the weights associated with each unit is bounded by A and the input dimension is n. We show that the misclassification probability is no more than a certain error estimate (that is related to squared error on the training set) plus A3 √((log n)/m) (ignoring log A and log m factors), where m is the number of training patterns. This may explain the generalization performance of neural networks, particularly when the number of training examples is considerably smaller than the number of weights. It also supports heuristics (such as weight decay and early stopping) that attempt to keep the weights small during training. The proof techniques appear to be useful for the analysis of other pattern classifiers: when the input domain is a totally bounded metric space, we use the same approach to give upper bounds on misclassification probability for classifiers with decision boundaries that are far from the training examples.

Quality and efficacy of the Indigenous Tutorial Assistance Scheme (ITAS) for university students

Designed as a 'supplementary' tuition scheme, the Indigenous Tutorial Assistance Scheme (hereafter referred to as ITAS) is a strategic initiative of the National Indigenous Education Policy (DEET, 1989). This paper seeks to contribute to the literature of the analysis of the quality and efficacy of ITAS. Currently, the delivery of ITAS to Indigenous students requires enormous administration and commitment by the staff of Indigenous education support centres. In exploring the essential but problematic provision of ITAS to Indigenous university students, this paper provides insights into significant aspects of our program that move beyond assumptions of student deficit, by researching the quality of teaching and learning through ITAS, analysing administrative workload, and sharing innovations to our program as a result of participatory research with important ITAS stakeholders.