Australian Research Council (ARC)

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This is a collection of ARC-funded research publications authored by Flinders academics.

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Now showing 1 - 20 of 89

Adabook and Multibook: adaptive boosting with chance correction
(2013-09) Powers, David Martin
There has been considerable interest in boosting and bagging, including the combination of the adaptive techniques of AdaBoost with the random selection with replacement techniques of Bagging. At the same time there has been a revisiting of the way we evaluate, with chance-corrected measures like Kappa, Informedness, Correlation or ROC AUC being advocated. This leads to the question of whether learning algorithms can do better by optimizing an appropriate chance corrected measure. Indeed, it is possible for a weak learner to optimize Accuracy to the detriment of the more reaslistic chance-corrected measures, and when this happens the booster can give up too early. This phenomenon is known to occur with conventional Accuracy-based AdaBoost, and the MultiBoost algorithm has been developed to overcome such problems using restart techniques based on bagging. This paper thus complements the theoretical work showing the necessity of using chance-corrected measures for evaluation, with empirical work showing how use of a chance-corrected measure can improve boosting. We show that the early surrender problem occurs in MultiBoost too, in multiclass situations, so that chance-corrected AdaBook and Multibook can beat standard Multiboost or AdaBoost, and we further identify which chance-corrected measures to use when.
Ancient DNA reveals elephant birds and kiwi are sister taxa and clarifies ratite bird evolution
(American Association for the Advancement of Science, 2014-05-23) Mitchell, Kieren J; Llamas, Bastien; Soubrier, Julien; Rawlence, Nicolas J; Worthy, Trevor; Wood, Jamie; Lee, Michael S Y; Cooper, Alan
The evolution of the ratite birds has been widely attributed to vicariant speciation, driven by the Cretaceous breakup of the supercontinent Gondwana. The early isolation of Africa and Madagascar implies that the ostrich and extinct Madagascan elephant birds (Aepyornithidae) should be the oldest ratite lineages. We sequenced the mitochondrial genomes of two elephant birds and performed phylogenetic analyses, which revealed that these birds are the closest relatives of the New Zealand kiwi and are distant from the basal ratite lineage of ostriches. This unexpected result strongly contradicts continental vicariance and instead supports flighted dispersal in all major ratite lineages. We suggest that convergence toward gigantism and flightlessness was facilitated by early Tertiary expansion into the diurnal herbivory niche after the extinction of the dinosaurs.
Apologies demanded yet devalued: Normative dilution in the age of apology
(Elsevier, 2015-07) Okimoto, Tyler Gene; Wenzel, Michael; Hornsey, Matthew J
Dramatic increases in the issuance of political apologies over the last two decades mean that we now live in the “age of apology”. But what does this surge in frequency mean for the effectiveness of intergroup apologies in promoting forgiveness? In the current research we propose a paradoxical “normative dilution” effect whereby behavioral norms increase the perceived appropriateness of an action while at the same time reducing its symbolic value. We experimentally manipulated the salience of the age-of-apology norm prior to assessing participant (N=128) reactions to past unjust treatment of ingroup prisoners of war by the Japanese during World War II. The apologetic norm increased victim group members’ desire for an apology in response to the harm. However, after reading the actual apology, the invocation of the norm decreased perceived apology sincerity and subsequent willingness to forgive. Thus, although apologetic trends may suggest greater contemporary interest in seeking reconciliation and harmony, their inflationary use risks devaluing apologies and undermining their effectiveness.
Application of polymer interlayers in silicon–carbon nanotube heterojunction solar cells
(WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2015-02-27) Yu, Le Ping; Tune, Daniel David; Shearer, Cameron; Shapter, Joseph George
We explore the use of polymers as a conducting interlayer within silicon–carbon nanotube heterojunction photovoltaics. Three types of devices have been fabricated and characterized including silicon–carbon nanotube, silicon–conducting polymer and silicon–conducting polymer–carbon nanotube. The conducting polymers studied were polyaniline, poly(3-hexylthiophene-2,5-diyl) and poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate). A thin conducting polymer interlayer significantly improves photovoltaic performance by creating a better depletion layer within the underlying silicon. With the addition of a top antireflection layer, a photovoltaic device, silicon-poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate)–carbon nanotube–poly(styrene) has been fabricated with a photovoltaic conversion efficiency of 8.7 %.
Asymmetries in attention as revealed by fixations and saccades
(Springer Verlag, 2014-06-21) Thomas, Nicole A; Loetscher, Tobias; Nicholls, Michael Elmo Richard
Neurologically normal individuals devote more attention to the left side; an asymmetry known as pseudoneglect, which reflects right hemisphere involvement in visuospatial attention. The role of eye movements in attentional asymmetries has received little consideration, particularly in terms of the greyscales task. Stimulus length, elevation, and presentation duration were manipulated, while monitoring eye movements during the greyscales task. Region of interest analyses compared time spent examining each quadrant of the stimulus. Further, saccades were examined in conjunction with fixations to gain an understanding of overall eye movement patterns. Scatterplots combining x-and y-coordinates illustrate mean eye position. Results demonstrated a comparison strategy was used, where the dark portions of each rectangle were fixated. Mean eye position was within the lower left quadrant. The left visual field was inspected most for the baseline condition. Interestingly, the lower visual field was examined most when duration, length, or elevation was manipulated. Eye movement patterns provide a possible explanation for why correlations are y not observed between visuospatial tasks. Different strategies, based on specific-task demands, are likely to be used, which in turn, engage separate aspects of visuospatial attention.
Attentional bias modification encourages healthy eating
(Elsevier, 2014-01) Kakoschke, Naomi; Kemps, Eva Bertha; Tiggemann, Marika
The continual exposure to unhealthy food cues in the environment encourages poor dietary habits, in particular consuming too much fat and sugar, and not enough fruit and vegetables. According to Berridge’s (1996) model of food reward, unhealthy eating is a behavioural response to biased attentional processing. The present study used an established attentional bias modification paradigm to discourage the consumption of unhealthy food and instead promote healthy eating. Participants were 146 undergraduate women who were randomly assigned to two groups: one was trained to direct their attention toward pictures of healthy food (‘attend healthy’ group) and the other toward unhealthy food (‘attend unhealthy’ group). It was found that participants trained to attend to healthy food cues demonstrated an increased attentional bias for such cues and ate relatively more of the healthy than unhealthy snacks compared to the ‘attend unhealthy’ group. Theoretically, the results support the postulated link between biased attentional processing and consumption (Berridge, 2009). At a practical level, they offer potential scope for interventions that focus on eating well.
Attentional Retraining Can Reduce Chocolate Consumption
(American Psychological Association, 2014-03) Kemps, Eva Bertha; Tiggemann, Marika; Orr, Jenna; Grear, Justine
There is emerging evidence that attentional biases are related to the consumption of substances such as alcohol and tobacco, and that attentional bias modification can reduce unwanted consumption of these substances. We present evidence for the first time that the same logical argument applies in the food and eating domain. We conducted two experiments which used a modified dot probe paradigm to train undergraduate women to direct their attention toward (‘attend’) or away from (‘avoid’) food cues (i.e., pictures of chocolate). In Experiment 1, attentional bias for chocolate cues increased in the ‘attend’ group, and decreased in the ‘avoid’ group. Experiment 2 showed that these training effects generalised to novel, previously unseen, chocolate pictures. Importantly, attentional re-training affected chocolate consumption and craving. In both experiments, participants in the ‘avoid’ group ate less chocolate in a so-called taste test than did those in the ‘attend’ group. Additionally, in Experiment 2, but not in Experiment 1, the ‘attend’ group reported stronger chocolate cravings following training, whereas the ‘avoid’ group reported less intense cravings. The results support predictions of cognitive-motivational models of craving and consumption that attentional biases play a causal role in consumption behaviour. Furthermore, they present a promising avenue for tackling unwanted food cravings and (over)eating. Keywords: food cues; attentional bias modification; dot probe task; consumption; craving
Averaging and linear programming in some singularly perturbed problems of optimal control
(Springer Verlag, 2014-06-11) Gaitsgory, Vladimir; Rossomakhine, Sergey
The paper aims at the development of an apparatus for analysis and construction of near optimal solutions of singularly perturbed (SP) optimal controls problems (that is, problems of optimal control of SP systems) considered on the infinite time horizon. We mostly focus on problems with time discounting criteria but a possibility of the extension of results to periodic optimization problems is discussed as well. Our consideration is based on earlier results on averaging of SP control systems and on linear programming formulations of optimal control problems. The idea that we exploit is to first asymptotically approximate a given problem of optimal control of the SP system by a certain averaged optimal control problem, then reformulate this averaged problem as an infinite-dimensional linear programming (LP) problem, and then approximate the latter by semi-infinite LP problems. We show that the optimal solution of these semi-infinite LP problems and their duals (that can be found with the help of a modification of an available LP software) allow one to construct near optimal controls of the SP system. We demonstrate the construction with two numerical examples.
Avifauna from the Teouma Lapita Site, Efate Island, Vanuatu, Including a New Genus and Species of Megapode
(University of Hawaii Press, 2015) Worthy, Trevor; Hawkins, Stuart; Bedford, Stuart; Spriggs, Matthew
The avifauna of the Teouma archaeological site on Efate in Vanuatu is described. It derives from the Lapita levels (3,000 â€“ 2,800 ybp) and immedi-ately overlying middens extending to âˆ¼2,500 ybp. A total of 30 bird species is represented in the 1,714 identiï¬ ed specimens. Twelve species are new records for the island, which, added to previous records, indicates that minimally 39 land birds exclusive of passerines were in the original avifauna. Three-fourths of the 12 newly recorded species appear to have become extinct by the end of Lapita times, 2,800 ybp. The avifauna is dominated by eight species of columbids (47.5% Minimum Number Individuals [MNI ]) including a large extinct tooth-billed pigeon, Didunculus placopedetes from Tonga, and a giant Ducula sp. cf. D. goliath from New Caledonia. Seabirds are rare despite the coastal location of the site. Fowl are important contributors to the Teouma avifauna, with the human-introduced Red Junglefowl Gallus gallus accounting for 15% MNI and present in all sampled layers. There are two species of megapodes (âˆ¼10% of MNI ), with the extant Vanuatu Megapode Megapodius layardi most abundant and represented at all levels in the deposits. A substantially larger extinct megapode, Mwalau walter-linii, n. gen., n. sp., is present only in the Lapita midden area, where it is rela-tively rare. This extinct species was larger than all extant megapodes but smaller than the extinct Progura gallinacea from Australia, with proportions most similar to those of Alectura, and was a volant bird. The remaining signiï¬ cant faunal component is rails, with four species present, of which Porphyrio melanotus was the most abundant. Rare but notable records include an undescribed large rail; a parrot, Eclectus sp. cf. E. infectus; a hornbill, Rhyticeros sp. cf. R. plicatus; and a coucal, Centropus sp. indet., all conservatively considered likely to be conspeciï¬ c with known taxa elsewhere in Melanesia.
A bittern (Aves: Ardeidae) from the Early Miocene of New Zealand
(Springer Verlag, 2013) Worthy, Trevor; Worthy, Jennifer P; Tennyson, Alan J D; Scofield, R Paul
Boundary restriction for negative emotional images is an example of memory amplification
(Sage Publications, 2015-04-02) Takarangi, Melanie K T; Oulton, Jacinta M; Green, Deanne M; Strange, Deryn
We investigated whether boundary restriction—misremembering proximity to traumatic stimuli—is a form of memory amplification and whether re-experiencing trauma plays a role in boundary restriction errors. In four experiments, subjects viewed a series of traumatic photographs. Later, subjects identified the photographs they originally saw among distracters that could be identical, close-up, or wide-angled versions of the same photographs. Subjects also completed measures of mood, analogue PTSD symptoms, phenomenological experience of intrusions, and processing style. Across experiments, subjects were more likely to incorrectly remember the photographs as having extended boundaries: boundary extension. Despite this tendency, the extent to which subjects re-experienced traumatic aspects of the photographs predicted how often they incorrectly remembered the photographs as having narrower boundaries: boundary restriction. Our data suggest that although boundary extension is more common, boundary restriction is related to individual differences in coping mechanisms post-trauma. These results have theoretical implications for understanding how people remember trauma.
Carbon-fiber amperometry in the study of exocytosis
(Humana Press: Springer, 2014) Duffield, Michael D; Raghupathi, Ravinarayan; Keating, Damien John
Our laboratory has utilized a non-invasive method of measuring the release of oxidizable molecules from cells, known as carbon-fiber amperometry.
Close to me: the effect of asymmetrical environments on spatial attention
(Taylor & Francis, 2014-03-26) Nicholls, Michael Elmo Richard; Roden, Sally; Thomas, Nicole A; Loetscher, Tobias; Spence, Charles J; Forte, Jason D
Attention can be captured by distractors and can affect performance. To examine whether asymmetrical distractors, such as a wall, affect spatial attention, Experiment 1 required participants (n = 20) to determine the relative length of pre-bisected lines when a temporary barrier was placed close to the left or right sides of the display. Post-hoc tests showed that attention was drawn towards left, but not right, walls. Experiment 2 (n = 18) sought to increase this effect using a solid brick wall rather than a temporary barrier. Instead of strengthening the result, no effect of barrier was observed. A non-effect was also observed in Experiment 3 (n = 18) when participants moved a cursor to the line's middle. Finally, Experiment 4 (n = 26) showed that asymmetrical barriers had no effect on visual search. While the data showed some evidence that attention is distracted by walls placed to the left, this effect is weak and task-specific.
Cohort Profile: The Australian Longitudinal Study of Ageing (ALSA)
(Oxford University Press, 2014-12-01) Luszcz, Mary Alice; Giles, Lynne Catherine; Anstey, Kaarin Jane; Browne-Yung, Kathryn; Walker, Ruth Ballance; Windsor, Timothy D
In response to the expressed need for more sophisticated and multidisciplinary data concerning ageing of the Australian population, the Australian Longitudinal Study of Ageing (ALSA) was established some two decades ago in Adelaide, South Australia. At Baseline in 1992, 2087 participants living in the community or in residential care (ranging in age from 65 to 103 years) were interviewed in their place of residence (1031 or 49% women), including 565 couples. By 2013, 12 Waves had been completed; both face-to-face and telephone personal interviews were conducted. Data collected included self-reports of demographic details, health, depression, morbid conditions, hospitalization, gross mobility, physical performance, activities of daily living, lifestyle activities, social resources, exercise, education and income. Objective performance data for physical and cognitive function were also collected. The ALSA data are held at the Flinders Centre for Ageing Studies, Flinders University. Procedures for data access, information on collaborations, publications and other details can be found at [http://flinders.edu.au/sabs/fcas/].
Collecting and conserving code: challenges and strategies
(Department of Media, Music, Communication and Cultural Studies, Macquarie University, Sydney, 2013) Swalwell, Melanie Lorraine; de Vries, Denise Bernadette
The collection and conservation of code is still in its infancy in Australia. Even where coded items do exist, they are almost completely invisible within local cultural institutions and archives. Born-digital heritage faces unique risks - the degradation of hardware and software, obsolete operating systems, and intellectual property laws that restrict digital preservation activities. Too often, governments and cultural institutions either fail to recognise the precarious situation of historic code-based media, or are not able to respond in an appropriate fashion, due to a lack of resources, know-how, or sometimes, will. After outlining some of the challenges - for institutions and researchers - of developing collections of games and other software, this article will detail two current research initiatives. The Play It Again project is conducting research into the largely unknown histories of 1980s game development in Australia and New Zealand, ensuring that local titles are documented, preserved and make it into national collections. The Australasian Heritage Software Database seeks to: draw together existing knowledge about locally-developed software, marshal a network of supporters, and develop an enabling discourse that supports research into histories of software and digital preservation. Whilst these projects do not provide complete solutions by any means, a local discourse about the importance of collecting and conserving code is emerging.
Combined effects of cognitive bias for food cues and poor inhibitory control on unhealthy food intake
(Elsevier BV, 2015-01-12) Kakoschke, Naomi; Kemps, Eva Bertha; Tiggemann, Marika
The present study aimed to investigate the combined effects of cognitive bias (attentional and approach biases) and inhibitory control on unhealthy snack food intake. Cognitive biases reflect automatic processing, while inhibitory control is an important component of controlled processing. Participants were 146 undergraduate women who completed a dot probe task to assess attentional bias and an approach-avoidance task to assess approach bias. Inhibitory control was measured with a food-specific go/no-go task. Unhealthy snack food intake was measured using a so-called “taste test”. There was a significant interaction between approach bias and inhibitory control on unhealthy snack food intake. Specifically, participants who showed a strong approach bias combined with low inhibitory control consumed the most snack food. Theoretically, the results support contemporary dual-process models which propose that behaviour is guided by both automatic and controlled processing systems. At a practical level, the results offer potential scope for an intervention that combines re-training of both automatic and controlled processing.
A computationally and cognitively plausible model of supervised and unsupervised learning
(Springer-Verlag, 2013-01-01) Powers, David Martin
The issue of chance correction has been discussed for many decades in the context of statistics, psychology and machine learning, with multiple measures being shown to have desirable properties, including various definitions of Kappa or Correlation, and the psychologically validated ΔP measures. In this paper, we discuss the relationships between these measures, showing that they form part of a single family of measures, and that using an appropriate measure can positively impact learning.
Cultural value vs culture's value
(Emerald Publishing Group, 2015) Meyrick, Julian; Barnett, Tully Sarah
The problem of culture’s value is assayed by David Throsby in his seminal book Economics and Culture when he puts forward the proposition “the economic impulse is individualistic, the cultural impulse is collective”. This proposition asserts, first, that there is behaviour which can be termed “economic” which reflects individual goals and which is portrayed in the standard model of an economy comprising self-interested individual consumers seeking to maximise their utility and self-interested producers seeking to maximise their profits […] secondly, that there is behaviour, distinguishable from economic behaviour […] which can be termed “cultural”; such behaviour reflects collective as distinct from individualistic goals, and derives from the nature of culture as expressing the beliefs, aspirations and identification of a group as defined above. Thus the cultural impulse can be seen as a desire for group experience or for collective production or consumption that cannot be fully factored out to the individuals comprising the group […] Whatever the artistic products produced and consumed, the processes of producing and consuming them can be seen not only as individual enterprise, but also as expressions of a collective will which transcends that of the individual participants involved.
Detection of CXCL13 transcript in hepatitis C virus-associated mixed cryoglobulinemia
(American Society of Hematology, 2015-02-05) Stempel, Andrew; Appukuttan, Binoy; Smith, Justine R
CXCL13 – also known as BLC in the mouse and BCA-1 in the human – is a chemokine with high selectivity for B lymphocytes. In seeking primers for detection of human CXCL13, we read the report by Sansonno et al. This work describes expression of CXCL13 in hepatitis C virus (HCV)-associated mixed cryoglobulinemia.
Distributions of Virus-Like Particles and Prokaryotes within Microenvironments
(Public Library of Science, 2016) Dann, Lisa M; Paterson, James; Newton, Kelly; Oliver, Rod L; Mitchell, James Gordon
Microbial interactions are important for ecosystem function, but occur at the microscale and so are difficult to observe. Previous studies in marine systems have shown significant shifts in microbial community abundance and composition over scales of micrometres to centimetres. This study investigates the microscale abundance distributions of virus-like particles (VLPs) and prokaryotes in the lower reaches of a river to determine the extent to which microscale microbial patchiness exists in freshwater systems. Here we report local hotspots surrounded by gradients that reach a maximum 80 and 107 fold change in abundance over 0.9 cm for prokaryotic and VLP subpopulations. Changes in prokaryotic and VLP hotspots were tightly coupled. There were no gradients at tens of centimetres across the boundary layers, which is consistent with strong mixing and turbulence-driven aggregation found in river systems. Quantification of the patchiness shows a marked asymmetry with patches 10 times greater than background common, but depletions being rare or absent in most samples. This consistent asymmetry suggests that coldspots depleted by grazing and lysis are rapidly mixed to background concentrations, while the prevalence of hotspots indicates persistence against disruption. The hotspot to coldspot relative abundance may be useful for understanding microbial river dynamics. The patchiness indicates that the mean- field approach of bulk phase sampling misses the microbially relevant community variation and may underestimate the concentrations of these important microbial groups.

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