Combining ganglion cell topology and data of patients with glaucoma to determine a structure-function map

PURPOSE: To introduce techniques for deriving a map that relates visual field locations to optic nerve head (ONH) sectors and to use the techniques to derive a map relating Medmont perimetric data to data from the Heidelberg Retinal Tomograph. METHODS: Spearman correlation coefficients were calculated relating each visual field location (Medmont M700) to rim area and volume measures for 10 degrees ONH sectors (HRT III software) for 57 participants: 34 with glaucoma, 18 with suspected glaucoma, and 5 with ocular hypertension. Correlations were constrained to be anatomically plausible with a computational model of the axon growth of retinal ganglion cells (Algorithm GROW). GROW generated a map relating field locations to sectors of the ONH. The sector with the maximum statistically significant (P < 0.05) correlation coefficient within 40 degrees of the angle predicted by GROW for each location was computed. Before correlation, both functional and structural data were normalized by either normative data or the fellow eye in each participant. RESULTS: The model of axon growth produced a 24-2 map that is qualitatively similar to existing maps derived from empiric data. When GROW was used in conjunction with normative data, 31% of field locations exhibited a statistically significant relationship. This significance increased to 67% (z-test, z = 4.84; P < 0.001) when both field and rim area data were normalized with the fellow eye. CONCLUSIONS: A computational model of axon growth and normalizing data by the fellow eye can assist in constructing an anatomically plausible map connecting visual field data and sectoral ONH data.

Contrast sensitivity changes due to glaucoma and normal aging: low-spatial-frequency losses in both magnocellular and parvocellular pathways

PURPOSE: To explore the effects of glaucoma and aging on low-spatial-frequency contrast sensitivity by using tests designed to assess performance of either the magnocellular (M) or parvocellular (P) visual pathways. METHODS: Contrast sensitivity was measured for spatial frequencies of 0.25 to 2 cyc/deg by using a published steady- and pulsed-pedestal approach. Sixteen patients with glaucoma and 16 approximately age-matched control subjects participated. Patients with glaucoma were tested foveally and at two midperipheral locations: (1) an area of early visual field loss, and (2) an area of normal visual field. Control subjects were assessed in matched locations. An additional group of 12 younger control subjects (aged 20-35 years) were also tested. RESULTS: Older control subjects demonstrated reduced sensitivity relative to the younger group for the steady (presumed M)- and pulsed (presumed P)-pedestal conditions. Sensitivity was reduced foveally and in the midperiphery across the spatial frequency range. In the area of early visual field loss, the glaucoma group demonstrated further sensitivity reduction relative to older control subjects across the spatial frequency range for both the steady- and pulsed-pedestal tasks. Sensitivity was also reduced in the midperipheral location of "normal" visual field for the pulsed condition. CONCLUSIONS: Normal aging results in a reduction of contrast sensitivity for the low-spatial-frequency-sensitive components of both the M and P pathways. Glaucoma results in a further reduction of sensitivity that is not selective for M or P function. The low-spatial-frequency-sensitive channels of both pathways, which are presumably mediated by cells with larger receptive fields, are approximately equivalently impaired in early glaucoma.

A naturally shaped silicone ventricle evaluated in a mock circulation loop : a preliminary study

Mock circulation loops are used to evaluate the performance of cardiac assist devices prior to animal and clinical testing. A compressible, translucent silicone ventricle chamber that mimics the exact size, shape and motion of a failing heart is desired to assist in flow visualization studies around inflow cannulae during VAD support. The aim of this study was therefore to design and construct a naturally shaped flexible left ventricle and evaluate its performance in a mock circulation loop. The ventricle shape was constructed by the use of CT images taken from a patient experiencing cardiomyopathic heart failure and used to create a 3D image and subsequent mould to produce a silicone ventricle. Different cardiac conditions were successfully simulated to validate the ventricle performance, including rest, left heart failure and VAD support.

Procurement selection in the public sector : a tale of two states.

The decision as to which procurement system to adopt is a complex and challenging task for clients of construction projects. Despite a plethora of tools and techniques available for selecting a procurement method, clients are still uncertain about what method to adopt for a given construction project to achieve success. This paper examines ‘how and why’ procurement methods are selected by public sector clients in Queensland (QLD) and Western Australia (WA). Findings from workshops with senior managers in procurement selection revealed that traditional lump sum methods (TLS) are preferred even though alternative forms could be better suited for a given project. Participants of the workshops agreed that alternative procurement forms should be considered for projects but an embedded culture of uncertainty avoidance meant the selection of TLS methods. It was perceived that only a limited number of contractors operating in the marketplace have the resources and experience to deliver projects using the non-traditional methods.

Enhancing Student Learning in Large Undergraduate Clasees by Using Audio-visual Case Studies

Critical skills such as identifying and appreciating issues that confront firms engaging in international business, and the ability to undertake creative decision-making, are considered fundamental to the study of International Business. It has been argued that using audio-visual case studies can help develop such skills. However, this is difficult due to a lack of Australian case studies. This paper reviews the literature outlining the advantages believed to result from the use of audio-visual case studies, describes a project implemented in a large cohort of students studying International Business, reports on a pilot evaluation of the project, and outlines the findings and conclusions of the survey.

Australian horror movies

The Australian horror film is a fascinating specimen. While a tradition has antecedents in the silent era of cinema, and at times has produced popular and commercially successful titles, Australian horror films have existed among the shadows of Australian cinema. Within a national cinema funded by public subsidy to foster a sense of national identity, emphasizing ‘quality’ cultural films and refusing to recognize popular movie genres in attempt to differentiate itself from Hollywood, generic and low-culture horror films have been in opposition to these objectives. Consequently, horror movies have been heavily marginalized within public funding environments and mainstream film culture, and either ignored or despised by mainstream critics. The chapter provides a historical introduction to Australian horror cinema before reviewing a selection of recent Aussie horror titles, namely: Wolf Creek, Undead, Black Water, Dying Breed, Lost Things, Prey, Cut, Rogue and Storm Warning.

Trends in National Party support

The National Party of Australia is under challenge. Will it be able to adapt and survive or will it become increasingly irrelevant in Australian politics? With population growth in some coastal and hinterland areas and decline in inland agricultural areas, the face of rural and regional Australia is changing. As a result, the National Party's traditional support is being eroded. Within the long-standing Coalition, the influence of the Nationals appears to be in decline, yet they continue to resist amalgamation with the Liberal Party.

Conceptual framework for managing knowledge of police deviance

This is a conceptual article on police deviance and its multi-faceted forms. It seeks to address the lack of an adequately formulated framework in the literature of the breadth and depth of police misconduct and corruption. The article argues for the use of a proposed ‘sliding scale’ of police deviance by examining the nature, extent and progression of police deviance and crime using research in Australia and Canada as illustrative case studies. This sliding scale is designed to research, capture and store, and hence extend the knowledge base of what constitutes police deviance at the level of the individual, the group and the organisational contexts of policing. As such, the conceptual framework is a robust yet flexible research tool and its utility as a sliding scale constitutes a step forward in advancing the knowledge on police deviance and criminality through adopting an integrated and holistic approach to managing such knowledge.

Assessing the safety of a velocity sourced series elastic actuator using the head injury criterion

The Velocity Sourced Series Elastic Actuator has been proposed as a method for providing safe force or torque based actuation for robots without compromising the actuator performance. In this paper we assess the safety of Velocity Sourced Series Elastic Actuators by measuring the Head Injury Criterion scores for collisions with a model head. The study makes a comparative analysis against stiff, high impedance actuation using the same motor without the series elastic component, showing that the series elastic component brings about a massive reduction in the chance of head injury. The benefits of a collision detection and safe reaction system are shown to be limited to collisions at low speeds, providing greater interaction comfort but not necessarily contributing to safety from injury.