An efficient algorithm for the detection of Eden

In this paper, a polynomial time algorithm is presented for solving the Eden problem for graph cellular automata. The algorithm is based on our neighborhood elimination operation which removes local neighborhood configurations which cannot be used in a pre-image of a given configuration. This paper presents a detailed derivation of our algorithm from first principles, and a detailed complexity and accuracy analysis is also given. In the case of time complexity, it is shown that the average case time complexity of the algorithm is \Theta(n^2), and the best and worst cases are \Omega(n) and O(n^3) respectively. This represents a vast improvement in the upper bound over current methods, without compromising average case performance.

Do drinking and riding mix? Effects of legal doses of alcohol on balance ability in experienced motorcyclists

The appropriateness of applying drink driving legislation to motorcycle riding has been questioned as there may be fundamental differences in the effects of alcohol on these two activities. For example, while the distribution of blood alcohol content (BAC) levels among fatally injured male drivers compared to riders is similar, a greater proportion of motorcycle fatalities involve levels in the lower (0 to .10% BAC) range. Several psychomotor and higher-order cognitive skills underpinning riding performance appear to be significantly influenced by low levels of alcohol. For example, at low levels (.02 to .046% BAC), riders show significant increases in reaction time to hazardous stimuli, inattention to the riding task, performance errors such as leaving the roadway and a reduced ability to complete a timed course. It has been suggested that alcohol may redirect riders’ focus from higher-order cognitive skills to more physical skills such as maintaining balance. As part of a research program to investigate the potential benefits of introducing a zero, or reduced, BAC for all riders in Queensland regardless of their licence status, the effects of low doses of alcohol on balance ability were investigated in a laboratory setting. The static balance of ten experienced riders was measured while they performed either no secondary task, a visual search task, or a cognitive (arithmetic) task following the administration of alcohol (0; 0.02, and 0.05% BAC). Subjective ratings of intoxication and balance impairment increased in a dose-dependent manner; however, objective measures of static balance were negatively affected only at the .05% BAC dose. Performance on a concurrent secondary visual search task, but not a purely cognitive (arithmetic) task, improved postural stability across all BAC levels. Finally, the .05% BAC dose was associated with impaired performance on the cognitive (arithmetic) task, but not the visual search task, when participants were balancing, but neither task was impaired by alcohol when participants were standing on the floor. Implications for road safety and future ‘drink riding’ policy considerations are discussed.

The impact of blur, illumination and distracters on tests related to driving performance

This thesis investigated a range of factors underlying the impact of uncorrected refractive errors on laboratory-based tests related to driving. Results showed that refractive blur had a pronounced effect on recognition of briefly presented targets, particularly under low light conditions. Blur, in combination with audio distracters, also slowed a participant's reactions to road hazards in video presentations. This suggests that recognition of suddenly appearing road hazards might be slowed in the presence of refractive blur, particularly under conditions of distraction. These findings highlight the importance of correcting even small refractive errors for driving, particularly at night.

Evaluating the impact of high risk foot training on undergraduate podiatry students

Background Diabetes is the leading cause of high risk foot (HRF) complications, admissions and lower limb amputation. Best practice training of podiatrists is known to have a beneficial impact on such outcomes; however, there has been a paucity of studies into undergraduate diabetes podiatry training. The primary aim of this paper was to investigate the changes in final year podiatry students’ confidence, knowledge and clinical practice in the management of HRF complications. Methods This was a prospective longitudinal study of final year podiatry students (n=25) at the Queensland University of Technology. All participants throughout 2011 undertook an intervention of a series of “hands on” HRF workshops, on-campus clinics and external clinical rotations. Outcome measures included customised confidence and knowledge surveys in HRF management across four time points. A timed simulated case scenario was used to evaluate changes in clinical practice at two time points. Friedman and Wilcoxon Signed Rank Tests were used to calculate differences between time points Results Overall improvements between the first and last time points were demonstrated in 20/21 confidence items (p<0.001), 12/27 clinical practice items (p<0.05) and 3/12 knowledge items (p<0.001). Although 8/12 knowledge items recorded high baseline scores of over 80%. Conclusions Overall, it appears student confidence and clinical practice improved with the introduction of designated HRF activities, whilst knowledge remained high. This suggests “hands on” practice and not didactic lectures improve students’ clinical confidence and practice. Results from the 2012 student cohort will also be presented at this conference.

A conceptualization of complexity in IS-driven organizational transformations

Organizational transformations reliant on successful ICT system developments (continue to) fail to deliver projected benefits even when contemporary governance models are applied rigorously. Modifications to traditional program, project and systems development management methods have produced little material improvement to successful transformation as they are unable to routinely address the complexity and uncertainty of dynamic alignment of IS investments and innovation. Complexity theory provides insight into why this phenomenon occurs and is used to develop a conceptualization of complexity in IS-driven organizational transformations. This research-in-progress aims to identify complexity formulations relevant to organizational transformation. Political/power based influences, interrelated business rules, socio-technical innovation, impacts on stakeholders and emergent behaviors are commonly considered as characterizing complexity while the proposed conceptualization accommodates these as connectivity, irreducibility, entropy and/or information gain in hierarchically approximation and scaling, number of states in a finite automata and/or dimension of attractor, and information and/or variety.

Hebbian reverberations in emotional memory micro circuits

The study of memory in most behavioral paradigms, including emotional memory paradigms, has focused on the feed forward components that underlie Hebb’s first postulate, associative synaptic plasticity. Hebb’s second postulate argues that activated ensembles of neurons reverberate in order to provide temporal coordination of different neural signals, and thereby facilitate coincidence detection. Recent evidence from our groups has suggested that the lateral amygdala (LA) contains recurrent microcircuits and that these may reverberate. Additionally this reverberant activity is precisely timed with latencies that would facilitate coincidence detection between cortical and sub cortical afferents to the LA.Thus, recent data at the microcircuit level in the amygdala provide some physiological evidence in support of the second Hebbian postulate.

Reliability and validity of physical fitness field tests for adults aged 55 to 70 years

The aim of this study was to examine the reliability and validity of field tests for assessing physical function in mid-aged and young-old people (55-70 y). Tests were selected that required minimal space and equipment and could be implemented in multiple field settings such as a general practitioner's office. Nineteen participants completed 2 field and I laboratory testing sessions. Intra-class correlations showed good reliability for the tests of upper body strength (lift and reach, R=.66), lower body strength (sit to stand, R=.80) and functional capacity (Canadian Step Test, R=.92), but not for leg power (single timed chair rise, R=.28). There was also good reliability for the balance test during 3 stances: parallel (94.7% agreement), semi-tandem (73.7%), and tandem (52.6%). Comparison of field test results with objective laboratory measures found good validity for the sit to stand (cf 1RM leg press, Pearson r=.68, p <.05), and for the step test (cf PWC140, r = -.60, p <.001), but not for the lift and reach (cf 1RM bench press, r=.43, p >.05), balance (r=-.13, -.18, .23) and rate of force development tests (r=-.28). It was concluded that the lower body strength and cardiovascular function tests were appropriate for use in field settings with mid-aged and young-old adults.

Endothelial precursor cells home to a vascularized tissue engineering chamber by application of the angiogenic chemokine CXCl12

Tissue engineering of vascularized constructs has great utility in reconstructive surgery. While we have been successful in generating vascularized granulation-like tissue and adipose tissue in an in vivo tissue engineering chamber, production of other differentiated tissues in a stable construct remains a challenge. One approach is to utilize potent differentiation factors, which can influence the base tissue. Endothelial precursor cells (EPCs) have the ability to both carry differentiation factors and home to developing vasculature. In this study, proof-of-principle experiments demonstrate that such cells can be recruited from the circulation into an in vivo tissue engineering chamber. CXC chemokine ligand 12 (CXCL12)/stromal cell-derived factor 1 was infused into the chamber through Alzet osmotic pumps and chamber cannulation between days 0 and 7, and facilitated recruitment of systemically inoculated exogenous human EPCs injected on day 6. CXCL12 infusion resulted in an eightfold increase in EPC recruitment, 2 (p = 0.03) and 7 days postinfusion (p = 0.008). Delivery of chemotactic/proliferation and/or differentiation factors and appropriately timed introduction of effective cells may allow us to better exploit the regenerative potential of the established chamber construct. © Copyright 2009, Mary Ann Liebert, Inc. 2009.

Reactive stepping behaviour in response to forward loss of balance predicts future falls in community-dwelling older adults

Background: a fall occurs when an individual experiences a loss of balance from which they are unable to recover. Assessment of balance recovery ability in older adults may therefore help to identify individuals at risk of falls. The purpose of this 12-month prospective study was to assess whether the ability to recover from a forward loss of balance with a single step across a range of lean magnitudes was predictive of falls. Methods: two hundred and one community-dwelling older adults, aged 65–90 years, underwent baseline testing of sensorimotor function and balance recovery ability followed by 12-month prospective falls evaluation. Balance recovery ability was defined by whether participants required either single or multiple steps to recover from forward loss of balance from three lean magnitudes, as well as the maximum lean magnitude participants could recover from with a single step. Results: forty-four (22%) participants experienced one or more falls during the follow-up period. Maximal recoverable lean magnitude and use of multiple steps to recover at the 15% body weight (BW) and 25%BW lean magnitudes significantly predicted a future fall (odds ratios 1.08–1.26). The Physiological Profile Assessment, an established tool that assesses variety of sensori-motor aspects of falls risk, was also predictive of falls (Odds ratios 1.22 and 1.27, respectively), whereas age, sex, postural sway and timed up and go were not predictive. Conclusion: reactive stepping behaviour in response to forward loss of balance and physiological profile assessment are independent predictors of a future fall in community-dwelling older adults. Exercise interventions designed to improve reactive stepping behaviour may protect against future falls.

STI-GMaS : an open-source environment for simulation of sexually-transmitted infections

Background Sexually-transmitted pathogens often have severe reproductive health implications if treatment is delayed or absent, especially in females. The complex processes of disease progression, namely replication and ascension of the infection through the genital tract, span both extracellular and intracellular physiological scales, and in females can vary over the distinct phases of the menstrual cycle. The complexity of these processes, coupled with the common impossibility of obtaining comprehensive and sequential clinical data from individual human patients, makes mathematical and computational modelling valuable tools in developing our understanding of the infection, with a view to identifying new interventions. While many within-host models of sexually-transmitted infections (STIs) are available in existing literature, these models are difficult to deploy in clinical/experimental settings since simulations often require complex computational approaches. Results We present STI-GMaS (Sexually-Transmitted Infections – Graphical Modelling and Simulation), an environment for simulation of STI models, with a view to stimulating the uptake of these models within the laboratory or clinic. The software currently focuses upon the representative case-study of Chlamydia trachomatis, the most common sexually-transmitted bacterial pathogen of humans. Here, we demonstrate the use of a hybrid PDE–cellular automata model for simulation of a hypothetical Chlamydia vaccination, demonstrating the effect of a vaccine-induced antibody in preventing the infection from ascending to above the cervix. This example illustrates the ease with which existing models can be adapted to describe new studies, and its careful parameterisation within STI-GMaS facilitates future tuning to experimental data as they arise. Conclusions STI-GMaS represents the first software designed explicitly for in-silico simulation of STI models by non-theoreticians, thus presenting a novel route to bridging the gap between computational and clinical/experimental disciplines. With the propensity for model reuse and extension, there is much scope within STI-GMaS to allow clinical and experimental studies to inform model inputs and drive future model development. Many of the modelling paradigms and software design principles deployed to date transfer readily to other STIs, both bacterial and viral; forthcoming releases of STI-GMaS will extend the software to incorporate a more diverse range of infections.

Executive function and postural instability in people with Parkinson’s disease

The specific aspects of cognition contributing to balance and gait have not been clarified in people with Parkinson’s disease (PD). Twenty PD participants and twenty age- and gender-matched healthy controls were assessed on cognition and clinical mobility tests. General cognition was assessed with the Mini Mental State Exam and the Addenbrooke’s Cognitive Exam. Executive function was evaluated using the Trail Making Tests (TMT-A and TMT-B) and a computerized cognitive battery which included a series of choice reaction time (CRT) tests. Clinical gait and balance measures included the Tinetti, Timed Up & Go, Berg Balance and Functional Reach tests. PD participants performed significantly worse than the controls on the tests of cognitive and executive function, balance and gait. PD participants took longer on Trail Making Tests, CRT-Location and CRT-Colour (inhibition response). Furthermore, executive function, particularly longer times on CRT-Distracter and greater errors on the TMT-B were associated with worse balance and gait performance in the PD group. Measures of general cognition were not associated with balance and gait measures in either group. For PD participants, attention and executive function were impaired. Components of executive function, particularly those involving inhibition response and distracters, were associated with poorer balance and gait performance in PD.

Your Loss is Our Gain

2 x 2.5 metre text based wall painting with a hidden automatic air freshener timed to spray every 60 seconds. The work formed part of a group exhibition that dealt with Humour,Politics and Art. It was part of a series of ongoing works made under the pseudonym Eve Roleston. Roleston is part of a trio of pseudonyms I use, the others being Ernesto Love, and Ernest Olove, to explore the research potential of the fictocritical in a visual arts practice.This forms part of an ongoing body of practice-led research undertaken in my PhD dealing with reconfiguring the relationship between art and politics.

The impact of litigation risk on the strategic timing of management earnings forecasts

This paper examines whether managers strategically time their earnings forecasts (MEFs) as litigation risk increases. We find as litigation risk increases, the propensity to release a delayed forecast until after the market is closed (AMC) or a Friday decreases but not proportionally more for bad news than for good news. Host costly this behaviour is to investors is questionable as share price returns do not reveal any under-reaction to strategically timed bad news MEF released AMC. We also find evidence consistent with managers timing their MEFs during a natural no-trading period to better disseminate information.

A review of pedestrian group dynamics and methodologies in modelling pedestrian group behaviours

Observations conducted by researchers revealed that the group interaction within crowds is a common phenomenon and has great influence on pedestrian behaviour. However, most research currently undertaken by various researchers failed to consider the group dynamics when developing pedestrian flow models. This paper presented a critical review of pedestrian models that incorporates group behaviour. Models reviewed in this paper are mainly created by microscopic modelling approaches such as social force, cellular automata, and agent-based method. The purpose of this literature review is to improve the understanding of group dynamics among pedestrians and highlight the need for considering group dynamics when developing pedestrian simulation models.

With budget cuts coming, ABC and SBS stand divided

Did SBS chief executive Michael Ebeid score a well-timed free kick or an own goal in his attack on the ABC this week? The ABC recently secured the free-to-air television rights for the Asian Cup football tournament to be held in Australia early next year, together with tonight’s match between the Socceroos and Japan. A lower bid by SBS – still in some circles fondly known as the “Soccer Broadcasting Service” – was rejected, dealing a significant blow to the smaller public broadcaster. The ABC was reportedly asked to make a bid by Football Federation Australia. The FFA presumably believes the ABC’s coverage will attract larger audiences to the game. This is despite SBS’s long-term success with the sport. It should not be forgotten, however, that while SBS has largely been defined by its long connection with the world game, ABC was the home of football from the late 1950s until the 1980s. But the stoush is only partly about football. It was surely no coincidence that it comes on the eve of the government’s formal announcement of the size of the cuts to public broadcasting...