Estimation of the depth focus from wavefront measurements

It is possible to estimate the depth of focus (DOF) of the eye directly from wavefront measurements using various retinal image quality metrics (IQMs). In such methods, DOF is defined as the range of defocus error that degrades the retinal image quality calculated from IQMs to a certain level of the maximum value. Although different retinal image quality metrics are used, currently there have been two arbitrary threshold levels adopted, 50% and 80%. There has been limited study of the relationship between these threshold levels and the actual measured DOF. We measured the subjective DOF in a group of 17 normal subjects, and used through-focus augmented visual Strehl ratio based on optical transfer function (VSOTF) derived from their wavefront aberrations as the IQM. For each subject, a VSOTF threshold level was derived that would match the subjectively measured DOF. Significant correlation was found between the subject’s estimated threshold level and the HOA RMS (Pearson’s r=0.88, p<0.001). The linear correlation can be used to estimate the threshold level for each individual subject, subsequently leading to a method for estimating individual’s DOF from a single measurement of their wavefront aberrations.

The role of cardiopulmonary signals in the dynamics of the eye's wavefront aberrations

Abstract—The role of cardiopulmonary signals in the dynamics of wavefront aberrations in the eye has been examined. Synchronous measurement of the eye’s wavefront aberrations, cardiac function, blood pulse, and respiration signals were taken for a group of young, healthy subjects. Two focusing stimuli, three breathing patterns, as well as natural and cycloplegic eye conditions were examined. A set of tools, including time–frequency coherence and its metrics, has been proposed to acquire a detailed picture of the interactions of the cardiopulmonary system with the eye’s wavefront aberrations. The results showed that the coherence of the blood pulse and its harmonics with the eye’s aberrations was, on average, weak (0.4 ± 0.15), while the coherence of the respiration signal with eye’s aberrations was, on average, moderate (0.53 ± 0.14). It was also revealed that there were significant intervals during which high coherence occurred. On average, the coherence was high (>0.75) during 16% of the recorded time, for the blood pulse, and 34% of the time for the respiration signal. A statistically significant decrease in average coherence was noted for the eye’s aberrations with respiration in the case of fast controlled breathing (0.5 Hz). The coherence between the blood pulse and the defocus was significantly larger for the far target than for the near target condition. After cycloplegia, the coherence of defocus with the blood pulse significantly decreased, while this was not the case for the other aberrations. There was also a noticeable, but not statistically significant, increase in the coherence of the comatic term and respiration in that case. By using nonstationary measures of signal coherence, a more detailed picture of interactions between the cardiopulmonary signals and eye’s wavefront aberrations has emerged.

The effect of presbyiopic vision corrections on nighttime driving performance

Purpose. To investigate the effect of various presbyopic vision corrections on nighttime driving performance on a closed-road driving circuit. Methods. Participants were 11 presbyopes (mean age, 57.3 ± 5.8 years), with a mean best sphere distance refractive error of R+0.23±1.53 DS and L+0.20±1.50 DS, whose only experience of wearing presbyopic vision correction was reading spectacles. The study involved a repeated-measures design by which a participant's nighttime driving performance was assessed on a closed-road circuit while wearing each of four power-matched vision corrections. These included single-vision distance lenses (SV), progressive-addition spectacle lenses (PAL), monovision contact lenses (MV), and multifocal contact lenses (MTF CL) worn in a randomized order. Measures included low-contrast road hazard detection and avoidance, road sign and near target recognition, lane-keeping, driving time, and legibility distance for street signs. Eye movement data (fixation duration and number of fixations) were also recorded. Results. Street sign legibility distances were shorter when wearing MV and MTF CL than SV and PAL (P < 0.001), and participants drove more slowly with MTF CL than with PALs (P = 0.048). Wearing SV resulted in more errors (P < 0.001) and in more (P = 0.002) and longer (P < 0.001) fixations when responding to near targets. Fixation duration was also longer when viewing distant signs with MTF CL than with PAL (P = 0.031). Conclusions. Presbyopic vision corrections worn by naive, unadapted wearers affected nighttime driving. Overall, spectacle corrections (PAL and SV) performed well for distance driving tasks, but SV negatively affected viewing near dashboard targets. MTF CL resulted in the shortest legibility distance for street signs and longer fixation times.

Australian construction industry KPIs

The Australian Construction Industry Forum (which is a peak industry association) and the Australian Procurement and Construction Council (which is a peak government organisation) have jointly agreed on a set of KPIs for the Australian Construction Industry. The goal of such a process is to work collaboratively in order to lift industry performance overall, and thereby bring about economic and social benefits to the industry and broader community. This paper seeks to underpin the process of KPI measurement by providing: an overview of international approaches to KPI measurement, summary of difficulties identified in performance measurement together with possible responses to these problems, and finally a discussion on the various methods for reporting KPIs. A number of findings throughout the paper, based on the review, made in order to advance the goal of performance measurement in the construction industry in Australia. Such findings would be relevant to other countries considering a KPI measurement process as well.

Integrated governance arrangements of airport-region urban infrastructure development : gaining insights from urban infrastructure development in the Brisbane airport region

Polarising the issue of governance is the increasingly acknowledged role of airports in regional economic development, both as significant sources of direct employment and as attractants of commerce through enhanced mobility (Vickerman, Spiekermann & Wegener 1999; Hakfoort, Poot & Rietveld 2001). Most airports were once considered spatially removed from their cities, but as cities have expanded their airports no longer sit distinct of the urban environment. This newfound spatial proximity means that decisions for land use and development on either city or airport land are likely to have impacts that affect one another in either or both the short- or long-term (Stevens, Baker and Freestone 2007). These impacts increase the demand for decision making to find ways of integrating strategies for future development to ensure that airport developments do not impede the sustainable growth of its city, and likewise that city developments do not impede the sustainable growth of its airport (Gillen 2006). However questions of how, under what conditions, and to what extent decision making integration might be suitable for “airport regions” are yet to be explored let alone answered.

The Simple Laws of Proportion

The Simple Laws of Proportion was shortlisted in the 2010 John Marsden Writing Prize for Young Australian Writers. It was subsequently published online by Express Media in December, 2010.

The Certainty of Yellow

Novel excerpt and discussion, as presented at the creative writing panel at Ignite! 2010

A green drought : the challenge of mentoring for Australian accounting academics

Purpose: The purpose of this paper is to expose the impact of the shortage of senior academics,particularly professors, in Australian accounting schools, to relate the way one school addressed this shortage through a mentoring scheme, and to challenge existing institutional arrangements.----------- Design/methodology/approach: This is a contextualised qualitative case study of a mentoring scheme conducted in an Australian accounting school. Data collected from semi-structured interviews, personal reflections and from Australian university web sites are interpreted theoretically using the metaphor of a “green drought”.---------- Findings: The mentoring scheme achieved some notable successes, but raised many issues and challenges. Mentoring is a multifaceted investment in vocational endeavour and intellectual infrastructure, which will not occur unless creative means are developed over the long term to overcome current and future shortages of academic mentors.---------- Research limitations/implications: This is a qualitative case study, which, therefore, limits its generalisability. However, its contextualisation enables insights to be applied to the wider academic environment. ----------Practical implications: In the Australian and global academic environment, as accounting professors retire in greater numbers, new and creative ways of mentoring will need to be devised. The challenge will be to address longer term issues of academic sustainability, and not just to focus on short-term academic outcomes.---------- Originality/value: A mentoring scheme based on a collegial networking model of mentoring is presented as a means of enhancing academic endeavour through a creative short-term solution to a shortage of accounting professors. The paper exemplifies the theorising power of metaphor in a qualitative study.

Who's afraid of the dark? Transpower New Zealand Ltd

On 12 June 2006, the lights went out in New Zealand’s largest city and major commercial centre, Auckland. Business was disrupted and many thousands of people inconvenienced. The unscheduled power cut was the latest in a series of electric power problems in New Zealand over the past decade. Attention turned to state-owned enterprise [SOE] Transpower, which was in charge of maintaining and developing New Zealand’s national electricity grid. The problem of 12 June was traced to two shackles in poor condition, small but essential parts of the electricity grid infrastructure. Closer examination of New Zealand’s electricity sector indicated these shackles were merely the tip of a power supply iceberg. Transpower’s Chief Executive, Ralph Craven, was now answerable to the Prime Minister for the issues creating the problems, and a workable solution to fix them. Transpower Chief Executive Ralph Craven needed to produce answers that went well beyond the problem of the two faulty shackles. The power crisis had brought to the fore wider issues of roles, responsibilities, and expectations in relation to the supply of electric power in New Zealand. Transpower was contending with these issues on a daily basis; however, the incident on 12 June publicly highlighted the urgent need for solutions that served the stakeholders in this critical industry.

Charity law reforms : overview of progress since 2001

In the UK, Singapore, Canada, New Zealand and Australia, as in many other jurisdictions, charity law is rooted in the common law and anchored on the Statute of Charitable Uses 1601. The Pemsel classification of charitable purposes was uniformly accepted, and together with a shared and growing pool of judicial precedents, aided by the ‘spirit and intendment’ rule, has subsequently allowed the law to develop along much the same lines. In recent years, all the above jurisdictions have embarked on law reform processes designed to strengthen regulatory processes and to statutorily define and encode common law concepts. The reform outcomes are now to be found in a batch of national charity statutes which reflect interesting differences in the extent to which their respective governments have been prepared to balance the modernising of charitable purposes and other common law concepts alongside the customary concern to tighten the regulatory framework.

Government : charity boundaries

The Preamble1 was the initial legislative statement of matters construed by government to constitute charitable purposes in a common law context. It provided an outline of what was to become the core agenda for government’s relationship with charity. The resulting implied partnership, as viewed by government, endured for four centuries and in many different cultural contexts across the common law world. During that period, judicial mediation on the balance to be struck between government interest in acquiring value for granting tax exempt privileges and the right of individuals to freely dispose of property in accordance with their particular altruistic wishes steadily broadened the range of purposes deemed to be charitable, the vagaries of donor choice often prevailing over government interest in acquiring value for tax exemption.

Modernising charity : steps to an alternative architecture for common law charity jurisprudence

This chapter addresses the question, how can the common law concept of charity law be modernised? There are difficulties with the present jurisprudential conception. The focus of the chapter is not on those difficulties, however, but rather on the development of an alternative architecture for common law jurisprudence. The conclusion to which the chapter comes is that charity law can be modernised by a series of steps to include all civil society organisations. It is possible if the ‘technical’ definition of charitable purpose is abandoned in favour of a contemporary, not technical concept of charitiable purpose. This conclusion is reached by proposing a framework, developed from the common law concept of charities, that reconciles into a cohesive jurisprudential architecture all of the laws applying to civil society organisations, not just charities. In this section, first the argument is contextualised in an idea of society and located in a gap in legal theory. An analogy is then offered to introduce the problems in the legal theory applying, not just to charities, but more broadly to civil society organisations. The substantive challenge of mapping an alternative jurisprudence is then taken in steps. The final substantive section conceptualises the changes inherent in a move beyond charities to a jurisprudence centred on civil society organisations and how this would bring legal theory into line with sectoral analysis in other disciplines.

Curriculum change in testing times

In these new, testing times, we need a new controlled rapid approach to curriculum change. Judy Smeed and TerrI Bourke explain.