Biomechanical force displacement analysis of strength of fixation of tracker holding devices to bone in computer aided joint replacement

Computer aided joint replacement surgery has become very popular during recent years and is being done in increasing numbers all over the world. The accuracy of the system depends to a major extent, on accurate registration and immobility of the tracker attachment devices to the bone. This study was designed to asses the forces needed to displace the tracker attachment devices in the bone simulators. Bone simulators were used to maintain the uniformity of the bone structure during the study. The fixation devices tested were 3mm diameter self drilling, self tapping threaded pin, 4mm diameter self tapping cortical threaded pin, 5mm diameter self tapping cancellous threaded pin and a triplanar fixation device ‘ortholock’ used with three 3mm pins. All the devices were tested for pull out, translational and rotational forces in unicortical and bicortical fixation modes. Also tested was the normal bang strength and forces generated by leaning on the devices. The forces required to produce translation increased with the increasing diameter of the pins. These were 105N, 185N, and 225N for the unicortical fixations and 130N, 200N, 225N for the bicortical fixations for 3mm, 4mm and 5mm diameter pins respectively. The forces required to pull out the pins were 1475N, 1650N, 2050N for the unicortical, 1020N, 3044N and 3042N for the bicortical fixated 3mm, 4mm and 5mm diameter pins. The ortholock translational and pull out strength was tested to 900N and 920N respectively and still it did not fail. Rotatory forces required to displace the tracker on pins was to the magnitude of 30N before failure. The ortholock device had rotational forces applied up to 135N and still did not fail. The manual leaning forces and the sudden bang forces generated were of the magnitude of 210N and 150N respectively. The strength of the fixation pins increases with increasing diameter from three to five mm for the translational forces. There is no significant difference in pull out forces of four mm and five mm diameter pins though it is more that the three mm diameter pins. This is because of the failure of material at that stage rather than the fixation device. The rotatory forces required to displace the tracker are very small and much less that that can be produced by the surgeon or assistants in single pins. Although the ortholock device was tested to 135N in rotation without failing, one has to be very careful not to put any forces during the operation on the tracker devices to ensure the accuracy of the procedure.

AITPM Email Newsletter Volume 0905, June 2009 : President's Message

President’s Message Hello fellow AITPM members, Due to three colliding forces of nature I find myself writing this month’s message from home – today, I am still getting over a persistent virus that seemed to set in just after returning from Singapore a couple of weeks ago, which my diabetes won’t let me get away with too easily (no Kermit the Frog swine flu jokes please). Combine this with a very wet day in Brisbane – in fact the wettest for 20 years (how can we complain, except for flash flooding?). And in Queensland today is a state school teachers’ strike, so one half of our brood is over watching TV. Family snapshots aside, the biggest news for our industry of late is the $8.5 billion announced in the Federal Budget for transport infrastructure projects; many “shovel ready”, but some – and fortunate for our profession – desktop ready. This newsletter provides nationwide coverage on the transport infrastructure aspects of the Federal Budget. We’ll need a bit more time to carefully look at the ensuing State Budgets’ announcements. Regarding the federal budget announcements, I am pleased to see serious attention being paid to upgrading the M1 system – I hope to see a motorway standard facility connecting Adelaide to at least Rockhampton in my lifetime. But some other important roads are of course missing out in this particular budget. Various levels of commitment are being made to urban passenger rail – some project significant while others planning significant. Enhancement of suburban rail is important across the capitals and Australia’s medium sized cities such as the Gold Coast and Newcastle. Not much on road safety initiatives jumped out at me, but I believe it is implied in the large road projects and in some of the detail elsewhere. I do believe it’s about time a ‘Vision Zero’ style policy is adopted at the National level, since any death is unacceptable on the road, just as it is in any other workplace. So, overall some good news on building transport infrastructure to keep the economy purring during this recession, and strongly supporting it during future boom times. The other edge to the sword, of course, is that we tax payers will be paying a considerable amount for borrowings for these projects over a long period of time. I close again in reminding everyone again that AITPM’s flagship event, the 2009 AITPM National Conference, Traffic Beyond Tomorrow, is being held in Adelaide from 5 to 7 August. www.aitpm.com has all of the details about how to register, sponsor a booth, session, etc. Best regards all, Jon Bunker

The problem of measurement indeterminacy in complex neurobiological movement systems

In the study of complex neurobiological movement systems, measurement indeterminacy has typically been overcome by imposing artificial modelling constraints to reduce the number of unknowns (e.g., reducing all muscle, bone and ligament forces crossing a joint to a single vector). However, this approach prevents human movement scientists from investigating more fully the role, functionality and ubiquity of coordinative structures or functional motor synergies. Advancements in measurement methods and analysis techniques are required if the contribution of individual component parts or degrees of freedom of these task-specific structural units is to be established, thereby effectively solving the indeterminacy problem by reducing the number of unknowns. A further benefit of establishing more of the unknowns is that human movement scientists will be able to gain greater insight into ubiquitous processes of physical self-organising that underpin the formation of coordinative structures and the confluence of organismic, environmental and task constraints that determine the exact morphology of these special-purpose devices.

Promoting creativity in education : from policy to practice : an Australian perspective

In the 21st century, our global community is changing to increasingly value creativity and innovation as driving forces in our lives. This paper will investigate how educators need to move beyond the rhetoric to effective practices for teaching and fostering creativity. First, it will describe the nature of creativity at different levels, with a focus on personal and everyday creativity. It will then provide a brief snapshot of creativity in education through the lens of new policies and initiatives in Queensland, Australia. Next it will review two significant areas related to enriching and enhancing students’ creative engagement and production: 1) influential social and environmental factors; and 2) creative self-efficacy. Finally, this paper will propose that to effectively promote student creativity in schools, we need to not only emphasise policy, but also focus on establishing a shared discourse about the nature of creativity, and researching and implementing effective practices for supporting and fostering creativity. This paper has implications for educational policy, practice and teacher training that are applicable internationally.

21st Century politics : new faces/new spaces

Politics has been described as a man’s game and a man’s place. Further, the design of houses of politics also embeds this dominant masculine ethos. Traditional Chambers have been large with only limited seating arrangements ensuring that only privileged elite can participate and both officials and the public are located at some distance and separate from the elected officials. Such a Chamber ensures that Members need to face each other and the dominant interaction is adversarial. Within this system however, women have been able to carve out new spaces, or use existing ones in different ways, to become more involved with the mechanisms of parliament and provide alternative routes to leadership. In doing so, they have introduced elements of the private domain (nurturing, dialogue and inclusion) to the public domain. The way in which space is used is fundamental and its treatment has consequences for individuals, organizations and societies (Clegg and Kornberger 2006). Dale’s (2005) work emphasises the social character of architecture which recognises the impact which it has on the behaviours of individuals and nowhere is this more pertinent than the way the Australian Parliament House operates. This paper draws on the experiences of Australian parliamentarians to examine the way in which the new Australian Parliament House shapes the way in which the Australian political cultural norms and practices are shaped and maintained. It also seeks to explore the way the Members of Parliament (MPs) experience these spaces and how some MPs have been able to bring new ways of utilising the space to ensure it is more accommodating to the men and women who inhabit this building at the apex of Australia’s political life. In doing so, such MPs are seeking to ensure that the practices and processes of Australia’s political system are reflective of the men and women who inhabit this national institution in the beginning of the 21st century.

Magnitude and variability of loading on the osseointegrated implant of transfemoral amputees during walking

This study directly measured the load acting on the abutment of the osseointegrated implant system of transfemoral amputees during level walking, and studied the variability of the load within and among amputees. Twelve active transfemoral amputees (age: 54±12 years, mass:84.3±16.3 kg, height: 17.8±0.10 m) fitted with an osseointegrated implant for over 1 year participated in the study. The load applied on the abutment was measured during unimpeded, level walking in a straight line using a commercial six-channel transducer mounted between the abutment and the prosthetic knee. The pattern and the magnitude of the three-dimensional forces and moments were revealed. Results showed a low step-to-step variability of each subject, but a high subject-to-subject variability in local extrema of body-weight normalized forces and moments and impulse data. The high subject-to-subject variability suggests that the mechanical design of the implant system should be customized for each individual, or that a fit-all design should take into consideration the highest values of load within a broad range of amputees. It also suggests specific loading regime in rehabilitation training are necessary for a given subject. Thus the loading magnitude and variability demonstrated should be useful in designing an osseointegrated implant system better able to resist mechanical failure and in refining the rehabilitation protocol.

Whither culture? Australian horror films and the limitations of cultural policy

Cultural policy that attempts to foster the Australian film industry’s growth and development in an era of globalisation is coming under increasing pressure. Throughout the 2000s, there has been a substantial boom in Australian horror films led by ‘runaway’ horror film Saw (2004), Wolf Creek (2005), and Undead (2003), achieving varying levels of popularity and commercial success worldwide. However, emerging within a national cinema driven by public subsidy and valuing ‘quality’ and ‘cultural content’ over ‘entertainment’ and ‘commercialism’, horror films have generally been antithetical to these objectives. Consequently, the recent boom in horror films has occurred largely outside the purview and subvention of cultural policy. This paper argues that global forces and emerging production and distribution models are challenging the ‘narrowness’ of cultural policy – a narrowness that mandates a particular film culture, circumscribes certain notions of value and limits the variety of films produced domestically. Despite their low-culture status, horror films have been well suited to the Australian film industry’s financial limitations, they are a growth strategy for producers, and a training ground for emerging filmmakers.

Leadership construction : an exploratory case study of two exemplary female principals in urban primary schools in mainland China

Worldwide, education systems have undergone unprecedented change due to a variety of economic, social, and political forces (Limerick, Cunnington & Crowther, 2002). The People’s Republic of China (PRC) is no exception. Continuous educational reform at primary and secondary levels in Mainland China has created new challenges and accountabilities for school principals. The important role of principals in primary and secondary schools has been acknowledged in both policy documents and the broader literature (Central Committee of the Chinese Communist Party, 1985; F. Chen, 2005; Chu, 2003; W. Huang, 2005; T. Wang, 2003). Yet, most of the literature on primary and secondary school principals in Mainland China is prescriptive in nature, identifying from the perspectives of researchers and academics what principals should do and how they should enact leadership. Lacking in this research is an awareness of the daily practices and lived experiences of principals. Furthermore, within the small body of writing on primary and secondary school principals in Mainland China, gender is seldom given any attention. To date, only a small number of empirical studies have focused on female principals as a specific category of research (Zen, 2004; Zhong, 2004). This study aimed to explore the professional lives of two female exemplary school principals in urban primary schools in Mainland China. A qualitative exploratory case study was used. Semi-structured interviews with each individual female principal, with six teachers in each of the school sites and with the superintendent of each principal were conducted. Field observations and document analysis were also undertaken to obtain multiple insights about their leadership practices. The conceptual framework was based largely on the theory of Gronn (1999) and incorporated five core leadership practices (vision building, ethical considerations, teaching and learning, power utilisation, and dealing with risks and challenges) taken from the wider literature. The key findings of this study were twofold. Firstly, while the five leadership practices were evident in the leadership of the two principals, this study identified some subtle differences in the way they approached each of them. Secondly, contextual factors such as Chinese traditional culture, the contemporary societal context, and the school organisational context, in addition to the biographical experiences of each principal were significant factors in shaping the way in which they exercised their leadership practices in the schools.

Report to the Government 2.0 Taskforce : Project 4 - Copyright Law and Intellectual Property

This report is the primary output of Project 4: Copyright and Intellectual Property, the aim of which was to produce a report considering how greater access to and use of government information could be achieved within the scope of the current copyright law. In our submission for Project 4, we undertook to address: •the policy rationales underlying copyright and how they apply in the context of materials owned, held and used by government; • the recommendations of the Copyright Law Review Committee (CLRC) in its 2005 report on Crown copyright; • the legislative and regulatory barriers to information sharing in key domains, including where legal impediments such as copyright have been relied upon (whether rightly or wrongly) to justify a refusal to provide access to government data; • copyright licensing models appropriate to government materials and examples of licensing initiatives in Australia and other relevant jurisdictions; and • issues specific to the galleries, libraries, archives and museums (“GLAM”) sector, including management of copyright in legacy materials and “orphan” works. In addressing these areas, we analysed the submissions received in response to the Government 2.0 Taskforce Issues Paper, consulted with members of the Task Force as well as several key stakeholders and considered the comments posted on the Task Force’s blog. This Project Report sets out our findings on the above issues. It puts forward recommendations for consideration by the Government 2.0 Task Force on steps that can be taken to ensure that copyright and intellectual property promote access to and use of government information.

The influence of oblique viewing on axial and peripheral refraction for emmetropes and myopes

Refraction may be affected by the forces of lids and extraocular muscles when eye direction and head direction are not aligned (oblique viewing) which might potentially influence past findings on peripheral refraction of the eye. We investigated the effect of oblique viewing on axial and peripheral refraction. In a first experiment, cycloplegic axial refractions were determined when subjects' heads were positioned to look straight-ahead through an open-view autorefractor and when the heads were rotated to the right or left by 30° with compensatory eye rotation (oblique viewing). Subjects were 16 young emmetropes (18–35 years), 22 young myopes (19–36 years) and 15 old emmetropes (45–60 years). In a second experiment, cycloplegic peripheral refraction measurements were taken out to ±34° horizontally from fixation while the subjects rotated their heads to match the peripheral refraction angles (eye in primary position with respect to the head) or the eyes were rotated with respect to the head (oblique viewing). Subjects were 10 emmetropes and 10 myopes. We did not find any significant changes in axial or peripheral refraction upon oblique viewing for any of the subject groups. In general for the range of horizontal angles used, it is not critical whether or not the eye is rotated with respect to the head during axial or peripheral refraction.

Introduction : the global flow of creative ideas

In the era of late modernism, various pressures play a decisive role in shaping the texture and meaning of the world around us. Population, work, transportation, new technologies of information and communication, lifestyle cultures and other forces are increasingly mobile, and this in turn helps make for a new set of public and personal surroundings. Social life everywhere now appears to share more and more in an international (if not a global) order, even if inequality and stratification remain common inside territories and across territories. Still, the perception is that a particular cultural life is increasingly universal. More and more consumers come to share in its practices and products, with those products becoming more and more homogeneous. This standardization argument finds much support in the apparent internationalization of many elements of media, entertainment, leisure and lifestyle cultures, with cultural conglomerates determined to maximize their global market reach. Once upon a time, in order to understand the economic, political and cultural forces affecting citizens and society, it was mostly deemed sufficient to look within the boundaries of the nation-state. Over the past two decades, these same pressures of globalization have impacted on critical research, highlighting the methodological need to adopt an optic that is more cross-border and transcultural as a means of gaining greater understanding of cultural life.

Seismic performance of brick infilled RC frame structures in low and medium rise buildings in Bhutan

The construction of reinforced concrete buildings with unreinforced infill is common practice even in seismically active country such as Bhutan, which is located in high seismic region of Eastern Himalaya. All buildings constructed prior 1998 were constructed without seismic provisions while those constructed after this period adopted seismic codes of neighbouring country, India. However, the codes have limited information on the design of infilled structures besides having differences in architectural requirements which may compound the structural problems. Although the influence of infill on the reinforced concrete framed structures is known, the present seismic codes do not consider it due to the lack of sufficient information. Time history analyses were performed to study the influence of infill on the performance of concrete framed structures. Important parameters were considered and the results presented in a manner that can be used by practitioners. The results show that the influence of infill on the structural performance is significant. The structural responses such as fundamental period, roof displacement, inter-storey drift ratio, stresses in infill wall and structural member forces of beams and column generally reduce, with incorporation of infill wall. The structures designed and constructed with or without seismic provision perform in a similar manner if the infills of high strength are used.

Printmaking as an expanding field in contemporary art practice : a case study of Japan, Australia and Thailand

This thesis proposes that contemporary printmaking, at its most significant, marks the present through reconstructing pasts and anticipating futures. It argues this through examples in the field, occurring in contexts beyond the Euramerican (Europe and North America). The arguments revolve around how the practice of a number of significant artists in Japan, Australia and Thailand has generated conceptual and formal innovations in printmaking that transcend local histories and conventions, whilst paradoxically, also building upon them and creating new meanings. The arguments do not portray the relations between contemporary and traditional art as necessarily antagonistic but rather, as productively dialectical. Furthermore, the case studies demonstrate that, in the 1980s and 1990s particularly, the studio practice of these printmakers was informed by other visual arts disciplines and reflected postmodern concerns. Departures from convention witnessed in these countries within the Asia-Pacific region shifted the field of the print into a heterogeneous and hybrid realm. The practitioners concerned (especially in Thailand) produced work that was more readily equated with performance and installation art than with printmaking per se. In Japan, the incursion of photography interrupted the decorative cast of printmaking and delivered it from a straightforward, craft-based aesthetic. In Australia, fixed notions of national identity were challenged by print practitioners through deliberate cultural rapprochements and technical contradictions (speaking across old and new languages).However time-honoured print methods were not jettisoned by any case study artists. Their re-alignment of the fundamental attributes of printmaking, in line with materialist formalism, is a core consideration of my arguments. The artists selected for in-depth analysis from these three countries are all innovators whose geographical circumstances and creative praxis drew on local traditions whilst absorbing international trends. In their radical revisionism, they acknowledged the specificity of history and place, conditions of contingency and forces of globalisation. The transformational nature of their work during the late twentieth century connects it to the postmodern ethos and to a broader artistic and cultural nexus than has hitherto been recognised in literature on the print. Emerging from former guild-based practices, they ambitiously conceived their work to be part of a continually evolving visual arts vocabulary. I argue in this thesis that artists from the Asia-Pacific region have historically broken with the hermetic and Euramerican focus that has generally characterised the field. Inadequate documentation and access to print activity outside the dominant centres of critical discourse imply that readings of postmodernism have been too limited in their scope of inquiry. Other locations offer complexities of artistic practice where re-alignments of customary boundaries are often the norm. By addressing innovative activity in Japan, Australia and Thailand, this thesis exposes the need for a more inclusive theoretical framework and wider global reach than currently exists for ‘printmaking’.

Class language

How social class factors into linguistic practices and use, language change and loss has been a major theme in postwar sociolinguistics and ethnography of communication, language planning and sociology of language. Key foci of linguistic and sociological research include the study of social class in everyday language use, media and institutional texts. A further concern is to understand the relationship between social class stratification, intergenerational social reproduction, and language variation. Bourdieu’s model of linguistic habitus and cultural capital offers a broad theoretical template for examining these relations, even as they are complicated by forces of economic and cultural globalization, new media and identity formations.

Militarising the body politic : new media as weapons of mass instruction

As militarization of bodies politic continues apace the world over, as military organizations again reveal themselves as primary political, economic and cultural forces in many societies, we argue that the emergent and potentially dominant form of political economic organization is a species of neo-feudal corporatism. Drawing upon Bourdieu, we theorize bodies politic as living habitus. Bodies politic are prepared for war and peace through new mediations, powerful means of public pedagogy. The process of militarization requires the generation of new, antagonistic evaluations of other bodies politic. Such evaluations are inculcated via these mediations, the movement of meanings across time and space, between formerly disparate histories, places, and cultures. New mediations touch new and different aspects of the body politic: its eyes, its ears, its organs, but they are consistently targeted at the formation of dispositions, the prime movers of action.