Left ventricular volume and valve gradient analysis using an Apple Macintosh computer

A description of a computer program to analyse cine angiograms of the heart and pressure waveforms to calculate valve gradients.

Virtual countries: Internet domain names and geographical terms

This paper examines the dispute between the Seattle company Virtual Countries Inc. and the Republic of South Africa over the ownership of the domain name address southafrica.com. The first part of the paper deals with the pre-emptive litigation taken by Virtual Countries Inc. in a District Court of the United States. The second part considers the possible arbitration of the dispute under the Uniform Domain Name Dispute Resolution Process of the Internet Corporation for Assigned Names and Numbers (ICANN) and examines the wider implications of this dispute for the jurisdiction and the governance of ICANN. The final section of the paper evaluates the Final Report of the Second WIPO Internet Domain Name Process.

The mechanical triggers of plaque rupture: Shear stress vs pressure gradient

The aim of this study was to evaluate the mechanical triggers that may cause plaque rupture. Wall shear stress (WSS) and pressure gradient are the direct mechanical forces acting on the plaque in a stenotic artery. Their influence on plaque stability is thought to be controversial. This study used a physiologically realistic, pulsatile flow, two-dimensional, cine phase-contrast MRI sequence in a patient with a 70% carotid stenosis. Instead of considering the full patient-specific carotid bifurcation derived from MRI, only the plaque region has been modelled by means of the idealised flow model. WSS reached a local maximum just distal to the stenosis followed by a negative local minimum. A pressure drop across the stenosis was found which varied significantly during systole and diastole. The ratio of the relative importance of WSS and pressure was assessed and was found to be less than 0.07% for all time phases, even at the throat of the stenosis. In conclusion, although the local high WSS at the stenosis may damage the endothelium and fissure plaque, the magnitude of WSS is small compared with the overall loading on plaque. Therefore, pressure may be the main mechanical trigger for plaque rupture and risk stratification using stress analysis of plaque stability may only need to consider the pressure effect.

Development of a transient gradient enhanced non local continuum damage mechanics model for masonry

Due to the advent of varied types of masonry systems a comprehensive failure mechanism of masonry essential for the understanding of its behaviour is impossible to be determined from experimental testing. As masonry is predominantly used in wall structures a biaxial stress state dominates its failure mechanism. Biaxial testing will therefore be necessary for each type of masonry, which is expensive and time consuming. A computational method would be advantageous; however masonry is complex to model which requires advanced computational modelling methods. This thesis has formulated a damage mechanics inspired modelling method and has shown that the method effectively determines the failure mechanisms and deformation characteristics of masonry under biaxial states of loading.

The transfer problem and the intertemporal terms of trade

In this paper the effects of a transfer on the intertemporal terms of trade are examined in the context of a simple two-country, two-period model. When intertemporal trade occurs because the two economies have different rates of time preference, a transfer improves the terms of trade of the paying country. Alternatively, when trade occurs owing to international differences in the endowments of goods over the two periods, the effect of a transfer depends on (a) the relationship between the interest rate and the rates of time preference of the two countries and (b) the relationship between their elasticities of intertemporal consumption substitution.

Improvising a future in the performing arts: The benefits of reframing performing arts entrepreneurship education in familiar terms

Improvisation is a central concept in any drama, theatre or performance studies degree. It is a critical skill, which helps performers learn to ‘make it up as they go along’, apply existing skills to new situations and environments, and, of course, adapt find the most effective or creative pathway towards a their aims. As such, the fact that improvisation is rarely listed as a core career competency — even for performing arts graduates, who can struggle to engage with entrepreneurial skill sets they will need to learn to manage their unpredictable portfolio careers when they are couched in business terms — is somewhat strange. This paper examines the benefits of reframing the administrative, management and entrepreneurial skills arts graduates need to navigate a complex, uncertain, constantly changing industrial landscape in terms of improvisation, play, and playful self - performance. It suggests that adding improvisation to our career training arsenal may be worthwhile, not just because it may assist graduates in navigating their way through a portfolio career, but because it may offer a more familiar, user- friendly terminology to assist graduates in understanding the need to develop administrative, management and entrepreneurial as well as artistic skills, and, in a sense, understand the similarities between the two sets of skills.

The prankster’s passion: Using theatrical terms to unpack players motivations in popular social performance

Amongst social players, the prank, as a social performance form, holds a lot of potential to impact on personal, relational and social status within a group or between one group and another group. More than simply showing off, a prank in the strictest definition of the term, is a social performance in which one player, a prankster, deploys mischief, trickery or deceit, to cause a moment of anxiety, fear or anger about a happening for another spectator-become-collaborating-player, a prankee – to enhance social bonds, entertain, or comment on a social, cultural or political phenomenon. During a prank, the prankster’s ability to be creative, clever or culturally astute, and the prankee’s ability to be duped, be a good sport, play along, or even play/pay the prankster back, both become fodder for other spectators and society to scrutinize. In Australia, pranking traditions are popular with many social groups, from the community-building pranks of footballers, bucks parties and ‘drop bear’ tales told to tourists, to the more controversial pranks of radio shock jocks, activists and artists. In this paper, I consider whether theatrical terms – theoretical terms from the stage such as actor, acting, objective, arc, performance, audience and emotion, such as those offered by Joseph Roach – are useful in understanding the passion some social players show for pranksterism. Are theatrical terms such as Roach’s as useful as analysts of social self-performance such as Erving Goffman suggest they are? Do they assist in understanding the personal actions, reactions and emotions of prankster and prankee? Do they assist in understanding the power relations between prankster and prankee? Do they assist in understanding the relation between the prank – be it an everyday prank amongst families, friends and coworkers, an entertainment program prank of the sort seen on Prank Patrol, Punked or Scare Tactics, or an activist pranks perpetrated by a guerrilla artist, ‘jammers’ or ‘hackers’ intent on turning dominant social systems back on themselves – the social players, and the public sphere in which the prank takes place? I reflect on how reading pranks as performances, by players, for highly participatory audiences, helps understand why they are so prevalent, and so recurrent across times, cultures and contexts, and also so controversial when not performed well enough – or when performed too well – prompting outrage from the prankster, prankee or society as passionate as any debate about a performance by players in a theatre.

Characterisation of head-hardened rail steel in terms of cyclic plasticity response and microstructure for improved material modelling

Stress- and strain-controlled tests of heat treated high-strength rail steel (Australian Standard AS1085.1) have been performed in order to improve the characterisation of the said material׳s ratcheting and fatigue wear behaviour. The hardness of the rail head material has also been studied and it has been found that hardness reduces considerably below four-millimetres from the rail top surface. Historically, researchers have used test coupons with circular cross-sections to conduct cyclic load tests. Such test coupons, typically five-millimetres in gauge diameter and ten‐millimetres in grip diameter, are usually taken from the rail head sample. When there is considerable variation of material properties over the cross-section it becomes likely that localised properties of the rail material will be missed. In another case from the literature, disks 47 mm in diameter for a twin-disk rolling contact test machine were obtained directly from the rail sample and used to validate ratcheting and rolling contact fatigue wear models. The question arises: How accurate are such tests, especially when large material property gradients exist? In this research paper, the effects of rail sampling location on the ratcheting behaviour of AS1085.1 rail steel were investigated using rectangular-shaped specimens obtained at four different depths to observe their respective cyclic plasticity behaviour. The microstructural features of the test coupons were also analysed, especially the pearlite inter-lamellar spacing which showed strong correlation with both hardness and cyclic plasticity behaviour of the material. This work ultimately provides new data and testing methodology to aid the selection of valid parameters for material constitutive models to better understand rail surface ratcheting and wear.