No description available.

We are interested in examining the long-time decay rate of a passive scalar in two-dimensional flows. The focus is on the effect of boundary conditions for kinematically prescribed velocity fields with random or periodic time dependence. Scalar evolution is followed numerically in a periodic geometry for families of flows that have either a slip or a no-slip boundary condition on a square or plane layer subdomain D. The boundary conditions on the passive scalar are imposed on the boundary C of the domain D by restricting to a subclass invariant under certain symmetry transformations. The scalar field obeys constant (Dirichlet) or no-flux (Neumann) conditions exactly for a flow with the slip boundary condition and approximately in the no-slip case. At late times the decay of a passive scalar, for example temperature, is exponential in time with a decay rate gamma(kappa), where kappa is the molecular diffusivity. Scaling laws of the form gamma(kappa) ~ C*kappa^alpha for small kappa are obtained numerically for a variety of boundary conditions on flow and scalar, and supporting theoretical arguments are presented. In particular when the scalar field satisfies a Neumann condition on all boundaries, alpha ~ 0 for a slip flow condition; for a no-slip condition we confirm results in the literature that alpha ~ 1/2 for a plane layer, but find alpha ~ 2/3 in a square subdomain D where the decay is controlled by stagnant flow in the corners. For cases where there is a Dirichlet boundary condition on one or more sides of the subdomain D, the exponent measuring the decay of the scalar field is alpha ~ 1/2 for a slip flow condition and alpha ~ 3/4 for a no-slip condition. The scaling law exponents alpha for chaotic time-periodic flows are compared with those for similarly constructed random flows. Motivated by the theory of passive scalar field, in Part II of this work we extend the investigation of the evolution of passive scalar for the flows addressed specifically in Part I. Based on an ensemble averaging over random velocity fields, the theoretical results obtained confirm the scaling laws computed numerically for a single, long realisation of random flows. In analogy with Lebedev and Turitsyn (2004) and Salman and Haynes (2007) our results show very good agreement between such an ensemble theory and applications. In part III of our study, we expand upon the work set out in the previous parts of this thesis in terms of the polar-co-ordinate system. We analyse the structures of flows driven near to a corner with a link to Moffatt corner eddies. A long-time exponential decay rate gamma(kappa)=C*kappa^alpha has been obtained confirming our numerical and theoretical results predicted in Part I and Part II in this work. The exponent alpha is determined in a structure of Moffatt corner eddies.

No description available.

The aim of this research study is to assess the ability of the Theory of Planned Behaviour (TpB) to explain people’s intentions to interact interracially on a social level. It aims to understand the influence of students’ attitudes, perceptions of social norms and efficacy on these intentions. A questionnaire survey was administered to 226 students (37% White, 31% Black African, 27% Asian and 4% Coloured). The questionnaire was based on the standard format of the Theory of Planned Behaviour (Ajzen, 1991). The TpB model explained 35% of the variability in intention, providing support for its predictive power. The attitude, subjective norm and perceived behavioural control components of the model had good predictive ability demonstrating the usefulness of the model as a means to explain and predict intention to mix interracially. The results indicated that attitudes to mixing was the most powerful predictor of intention to mix inter-racially followed by perceived ability to effect this behaviour. Perception of social norms, while also statistically significant, was the least important factor. The findings suggest that the major obstacles to inter-racial interaction are intergroup attitudes and perceived inability to make such contacts.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

In some rural and remote locations in New South Wales and elsewhere in Australia, a limited range of radiographic examinations may be performed by nurses and general practitioners if there is no radiographer available. These so called remote x-ray operators are licensed under the New South Wales Radiation Control Act 1990. This study aimed to investigate the experiences and perceptions of remote x-ray operator radiography and examine the role of remote operators in New South Wales from the perspective of a cohort of rural radiographers and nurse and GP remote x-ray operators involved in frontline delivery of rural radiographic services. Methodology Semi-structured in-depth interviews were performed with twenty rural radiographers, ten rural nurses and seven rural general practitioners from various rural communities in New South Wales. Interview questions explored the informants’ knowledge, opinions and values, experience and behaviour, and attitudes and feelings in relation to remote x-ray operator radiography. Interviews were tape-recorded and transcribed. Data analysis was subsequently performed using an iterative process based on a modified grounded theory methodology. Data labelling and comparative analysis were carried out in parallel with data collection, allowing progressive modification of the interview theme list to ensure that theoretical saturation was achieved. Results Data analysis led to the emergence of three key concepts, together with their relevant themes and sub-themes. The primary key concept, ‘Dimensions of Practice’, was inclusive of the central precepts of remote x-ray operator radiography. It includes themes titled ‘Licence Conditions and Limitations’, ‘Competency Requirements’ and ‘Image Quality and Practice Standards’. The key concept of ‘Service Provision and Equity of Access’, represents the realities of clinical practice in the rural and remote health care setting. It includes themes of ‘Clinical Management and Decision Making’, ‘Access and Availability’, ‘Patient Expectations’ and ‘Commitment to Service’. The third key concept is ‘Professional Roles and Relationships’, which deals with the interactions that take place between individual practitioners and the factors that influence them. It encompasses the xii themes of ‘Boundary Delineation’, ‘Professional Status and Esteem’ and ‘Interprofessional Conflict and Collaboration’. Relationships between the key concepts, via their themes and sub-themes were also explored. Conclusions Analysis of the data led to the development of a conceptual model and a single story line that represent the perspectives of the study informants. Remote x-ray operator radiography takes place at the intersection of the occupational worlds of rural radiographers, nurses and general practitioners. Remote operators provide a valuable service that prevents rural residents having to travel to access minor radiographic examinations. However, the quality of the radiography they perform is below the standard expected of radiographers. Improvements in collaborative teamwork could improve the quality of service, although interprofessional communication is stifled by status and hierarchical relationships. The remote x-ray operator experience may inform the development of future models of health care. / PhD Doctorate

<p>A central theme in Pauline Melville’s novel, The Ventriloquist’s Tale, is the question of endogamy and exogamy, with the opposing alternatives embodied in Melville’s characters. This theme has received much attention in the critical commentaries generated by the novel, with a prevailing number of critics claiming that Melville proposes endogamy as the only option for indigenous communities to remain intact. However, such an argument overlooks the significant fact that Melville’s characters are always already the offspring of exogamous encounters, through which a multiplicity of boundaries have been permeated. Furthermore, the spatial motifs developed in the novel can be seen to undermine commonly accepted delimitations of supposedly homogenous groups, the nation-state constituting the prime example, and this in turn profoundly alters the notion of mixing. Consequently, contending that Melville even enters a debate on endogamy and exogamy stems from a predisposition to see the world in other terms than those Melville sets out in her novel. The nature of boundaries and borders in Melville’s fictitious world are therefore explored using Benedict Anderson’s Imagined Communities as a framework. This examination shows that the novel undermines the notion of the nation-state as a homogenous entity and reveals a global structure that dictates and drives interaction on a global scale. Consequently, instead of a debate on exogamy, we see in the novel an exploration and dismantling of notions of borders, boundaries and barriers between individuals and groups of people.</p>

A central theme in Pauline Melville’s novel, The Ventriloquist’s Tale, is the question of endogamy and exogamy, with the opposing alternatives embodied in Melville’s characters. This theme has received much attention in the critical commentaries generated by the novel, with a prevailing number of critics claiming that Melville proposes endogamy as the only option for indigenous communities to remain intact. However, such an argument overlooks the significant fact that Melville’s characters are always already the offspring of exogamous encounters, through which a multiplicity of boundaries have been permeated. Furthermore, the spatial motifs developed in the novel can be seen to undermine commonly accepted delimitations of supposedly homogenous groups, the nation-state constituting the prime example, and this in turn profoundly alters the notion of mixing. Consequently, contending that Melville even enters a debate on endogamy and exogamy stems from a predisposition to see the world in other terms than those Melville sets out in her novel. The nature of boundaries and borders in Melville’s fictitious world are therefore explored using Benedict Anderson’s Imagined Communities as a framework. This examination shows that the novel undermines the notion of the nation-state as a homogenous entity and reveals a global structure that dictates and drives interaction on a global scale. Consequently, instead of a debate on exogamy, we see in the novel an exploration and dismantling of notions of borders, boundaries and barriers between individuals and groups of people.

β – Tricalcium phosphate (β-TCP, Ca3(PO4)2) is a commonly used bone substitute material due to its biocompatibility and resorption. This study focused on the production of almost fully dense β-TCP ceramics with varying degrees of impurities (Ca/PO4 ratio, addition of 5% Mg). Three methods were used to produce the β-TCP ceramics, uniaxial pressing, slip-casting and isostatic pressing. In this study the isostatic pressing and sintering at 1150ºC for 20h and 15min, resulted in the densest β-TCP ceramics (97.7-99.2%). No significant differences of grain size and density could be detected between the samples produced with various compositions. These isostatically pressed samples sintered at 1150ºC were then dissolved in 0.08M aceticacid solution to simulate the in vivo resorption. It was found that the samples containing extra Mg dissolved slower. Attempts to determine the chemical composition of the grain boundaries were made without success. However, SEM observations of partly dissolved β-TCP ceramics revealed that the grain boundaries dissolved faster than the grains. The study was performed at the RMS foundation in Switzerland.

The transition fundions for the correlated random walk with two absorbing boundaries are derived by means of a combinatorial construction which is based on Krattenthaler's Theorem for counting lattice paths with turns. Results for walks with one boundary and for unrestricted walks are presented as special cases. Finally we give an asymptotic formula, which proves to be useful for computational purposes. (author's abstract) / Series: Forschungsberichte / Institut für Statistik