ORCID Profile
0000-0003-2278-3766
Current Organisation
University of Tasmania
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Publisher: Informa UK Limited
Date: 23-04-2010
DOI: 10.1080/08927014.2010.482208
Abstract: The detrimental effect of biofilms on skin friction for near wall flows is well known. The diatom genera Gomphonema and Tabellaria dominated the biofilm mat in the freshwater open channels of the Tarraleah Hydropower Scheme in Tasmania, Australia. A multi-faceted approach was adopted to investigate the drag penalty for biofouled 1.0 m x 0.6 m test plates which incorporated species identification, drag measurement in a recirculating water tunnel and surface characterisation using close-range photogrammetry. Increases in total drag coefficient of up to 99% were measured over clean surface values for biofouled test plates incubated under flow conditions in a hydropower canal. The effective roughness of the biofouled surfaces was found to be larger than the physical roughness the additional energy dissipation was caused in part by the vibration of the biofilms in three-dimensions under flow conditions. The data indicate that there was a roughly linear relationship between the maximum peak-to-valley height of a biofilm and the total drag coefficient.
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.JDENT.2008.11.012
Abstract: Recent advances in digital photogrammetry have enabled a new approach to high resolution mapping of tooth surfaces. The aim of this study was to assess the accuracy and the precision of a new system using automatic digital stereo-photogrammetry combined with an experimental casting material and to measure tooth surface loss in a non-carious cervical lesion. A test object and tooth replicas incorporating optical texture obtained at baseline, one and 2 years were imaged with a pre-calibrated stereocamera. The stereoimagery was then processed with digital photogrammetric software to automatically generate digital surface models. Test object models were analysed for accuracy and precision and tooth surface models were aligned with point cloud analysis software and tooth surface loss determined. Replicas were mapped to an accuracy of (6+/-13)microm. The sensitivity of change detection on tooth replicas was 40 microm with change ranging from 40 to 70 microm per annum in a discrete part of the lesion. In the case examined, the change detection data were of sufficient accuracy and resolution to draw meaningful conclusions about the spatial distribution and quantum of tooth hard tissue loss. The results of this investigation suggest that annual change detection studies will provide a clearer picture of the pattern of tooth surface loss and, in combination with other analytical techniques, a more detailed explanation of the natural history of these lesions.
Publisher: Springer Science and Business Media LLC
Date: 08-01-2005
Publisher: Elsevier BV
Date: 04-2019
Publisher: Cambridge University Press (CUP)
Date: 02-1997
DOI: 10.1017/S0025315400033762
Abstract: Using video and image analysis techniques we analysed the response of swarms of the mysid Paramesopodopsis rufa to food and predatory attack. After food was added to the tank, mysid aggregations initially (up to 45 s) increased in volume. Subsequently volume decreased significantly until it was smaller than the initial level. After a period of ~12 h during which no food was added, the swarm expanded to near its original volume. These changes are interpreted as resulting from a need by in iduals to optimize food capture and protection. The pattern of volume changes in response to food was independent of aquarium size but the magnitude of the changes was reduced in a smaller tank. Predatory attacks on mysid swarms were simulated using a model fish which ‘swam’ a single pass along the tank driven by an electric motor. Models (latex-covered real preserved fish), represented two different attack styles: ambush (seahorse Hippoc us abdominalis ) and lunging (Australian salmon Arripis trutta ). ‘Swimming’ speeds resembled those measured for real fish i.e. 0·5–2·0 cm s -1 for seahorse and 15 cm s -1 for salmon. Again changes in swarm volume were recorded. No obvious response by the swarm to the approaching seahorse was apparent the aggregation simply parted to allow the fish through. No tailflips were seen among the mysids. The swarm resumed the original volume rapidly after the fish had passed. Approach of the salmon was evidently detected from further away, escape reactions were frequent and energetic, and tailflipping was common. After the fish had passed, it took longer for the original swarm volume to be restored. These results suggest that seahorse ambush techniques have evolved to minimize warning of the predator's approach. When the salmon ‘menaced’ the swarm at seahorse speeds, it appeared the mysids still reacted as though it was a ‘normal’ salmon attack so the fright response was not just a function of speed of attack. Dynamic changes in swarm volume seem to be a useful simple index of motivational state of in iduals.
Publisher: Springer Science and Business Media LLC
Date: 23-01-2019
DOI: 10.1038/S41598-018-37379-9
Abstract: Animal positions within moving groups may reflect multiple motivations including saving energy and sensing neighbors. These motivations have been proposed for schools of Antarctic krill, but little is known about their three-dimensional structure. Stereophotogrammetric images of Antarctic krill schooling in the laboratory are used to determine statistical distributions of swimming speed, nearest neighbor distance, and three-dimensional nearest neighbor positions. The krill schools swim at speeds of two body lengths per second at nearest neighbor distances of one body length and reach similarly high levels of organization as fish schools. The nearest neighbor position distribution is highly anisotropic and shows that Antarctic krill prefer to swim in the propulsion jet of their anterior neighbor. This position promotes communication and coordination among schoolmates via hydrodynamic signals within the pulsed jet created by the metachronal stroking of the neighboring krill’s pleopods. The hydrodynamic communication channel therefore plays a large role in structuring the school. Further, Antarctic krill avoid having a nearest neighbor directly overhead, possibly to avoid blockage of overhead light needed for orientation. Other factors, including the elongated body shape of Antarctic krill and potential energy savings, also may help determine the three dimensional spatial structure of tightly packed krill schools.
Publisher: Informa UK Limited
Date: 03-07-2018
Publisher: Informa UK Limited
Date: 03-1995
Publisher: Elsevier BV
Date: 03-2009
DOI: 10.1016/J.JDENT.2008.11.012
Abstract: Recent advances in digital photogrammetry have enabled a new approach to high resolution mapping of tooth surfaces. The aim of this study was to assess the accuracy and the precision of a new system using automatic digital stereo-photogrammetry combined with an experimental casting material and to measure tooth surface loss in a non-carious cervical lesion. A test object and tooth replicas incorporating optical texture obtained at baseline, one and 2 years were imaged with a pre-calibrated stereocamera. The stereoimagery was then processed with digital photogrammetric software to automatically generate digital surface models. Test object models were analysed for accuracy and precision and tooth surface models were aligned with point cloud analysis software and tooth surface loss determined. Replicas were mapped to an accuracy of (6+/-13)microm. The sensitivity of change detection on tooth replicas was 40 microm with change ranging from 40 to 70 microm per annum in a discrete part of the lesion. In the case examined, the change detection data were of sufficient accuracy and resolution to draw meaningful conclusions about the spatial distribution and quantum of tooth hard tissue loss. The results of this investigation suggest that annual change detection studies will provide a clearer picture of the pattern of tooth surface loss and, in combination with other analytical techniques, a more detailed explanation of the natural history of these lesions.
Publisher: Informa UK Limited
Date: 2005
Publisher: Elsevier BV
Date: 06-2001
DOI: 10.1016/S0022-0981(01)00265-9
Abstract: When feeding on mysid swarms (Paramesopodopsis rufa), juvenile Australian salmon (Arripis trutta) had higher rates of successful attacks when foraging in a group of six fish (55% total advances) than when foraging alone (39% total advances). Six schooling fish had lower approach rates than solitary fish (25% and 37% of total advances, respectively). This result indicated that schooling fish were better at reducing the confusion effect of swarming prey, resulting in more efficient feeding. In larger areas, schools achieved higher rates of successful attacks (19 prey/fish in the large tank, compared with 11 prey/fish in the smaller tank). There was no influence on the feeding success of in idual fish when changes were made to the number of prey presented to each fish. Nearest neighbour distances were smallest in the absence of prey, and increased with the introduction of prey and again in an attack sequence. Six fish schooled more cohesively than three fish, indicating increased benefits of schooling in larger groups that contribute to advanced vigilance and foraging techniques.
Publisher: Elsevier BV
Date: 06-2001
DOI: 10.1016/S0022-0981(01)00265-9
Abstract: When feeding on mysid swarms (Paramesopodopsis rufa), juvenile Australian salmon (Arripis trutta) had higher rates of successful attacks when foraging in a group of six fish (55% total advances) than when foraging alone (39% total advances). Six schooling fish had lower approach rates than solitary fish (25% and 37% of total advances, respectively). This result indicated that schooling fish were better at reducing the confusion effect of swarming prey, resulting in more efficient feeding. In larger areas, schools achieved higher rates of successful attacks (19 prey/fish in the large tank, compared with 11 prey/fish in the smaller tank). There was no influence on the feeding success of in idual fish when changes were made to the number of prey presented to each fish. Nearest neighbour distances were smallest in the absence of prey, and increased with the introduction of prey and again in an attack sequence. Six fish schooled more cohesively than three fish, indicating increased benefits of schooling in larger groups that contribute to advanced vigilance and foraging techniques.
Publisher: MDPI AG
Date: 17-09-2015
DOI: 10.3390/RS70911933
Publisher: Wiley
Date: 06-2008
Publisher: Cambridge University Press (CUP)
Date: 20-03-2003
DOI: 10.1017/S002531540300715XH
Abstract: Antarctic krill, Euphausia superba , normally live in social aggregations (schools) but rarely aggregate in laboratory tanks. In order to study the effect of stress on solitary living we tethered krill to wooden skewers and measured heart rate both when they were held isolated from conspecifics and when they were held at normal schooling distances (∼1 body length). Heart rate did not differ significantly with sex or body size. However, intermoult krill had a significantly lower heart rate than postmoult animals. When two in iduals were held at schooling distance, with one slightly higher in the water column than the other, the heart rate of the higher in idual slowed significantly (106–98 beats min −1 ), while that of the lower in idual remained the same. We interpret these results to mean that krill living solitarily are stressed but will respond to neighbouring in iduals by decreasing their metabolic rate and saving energy.
Publisher: International Union Against Tuberculosis and Lung Disease
Date: 21-06-2014
DOI: 10.5588/PHA.13.0091
Publisher: Wiley
Date: 06-2005
Publisher: Informa UK Limited
Date: 15-03-2010
DOI: 10.1080/08927011003699733
Abstract: The physical roughness of a surface changes when freshwater biofilms colonize and grow on it and this has significant implications for surfaces enclosing water conveying systems such as pipelines and canals. Plates with surfaces initially artificially roughened with varying grit size were deployed in an open channel system and biofilms were allowed to grow on the exposed surface. The plates were retrieved at intervals in time and their surfaces mapped using close range photogrammetry. For a fine grit surface (0.5-4 mm particles), diatom-dominated biofilms initially grew between the roughness elements they subsequently developed as a mat to create a physically smoother outer surface than the underlying rough surface. For a coarse grit surface (2-4 mm), biofilms colonized faster in one instance, larger clumps of biofilm were observed as transverse ripples across the plate.
Publisher: Wiley
Date: 05-2010
Publisher: Informa UK Limited
Date: 10-2016
Publisher: MDPI AG
Date: 28-11-2017
DOI: 10.3390/IJGI6120386
Publisher: Springer Science and Business Media LLC
Date: 08-01-2005
Publisher: Acoustical Society of America (ASA)
Date: 02-2002
DOI: 10.1121/1.1430682
Abstract: Movement of the external ear canal, associated with jaw motion, relative to the concha region of the pinna has been studied. Pairs of open-jaw and closed-jaw impressions were taken of 14 ears from 10 subjects. Three-dimensional coordinate data were obtained from the concha and the anterior surface of the canal using a reflex microscope. Proprietary area-based matching software was used to evaluate distortion of the two surfaces between the two jaw positions. The canal data from each pair were placed into the same coordinate system with their respective concha regions aligned. Difference maps of the canal data were used to demonstrate the amount of anterior–posterior (A–P), superior–inferior (S–I), and medial–lateral (M–L) movement, relative to the concha, that occurred between the open- and closed-jaw impressions. The concha regions did not undergo significant deformation. The canal regions underwent varying amounts of deformation with all canals conforming within an rms of 136 μm across the entire surface. The majority of canals underwent significant movement relative to the concha. M–L movement ranged from +2.0 to −3.8 mm eight canals moved laterally, five moved medially, and two showed no movement. S–I movement ranged from +3.7 to −2.7 mm nine canals moved inferiorly, two moved superiorly, and three showed no movement. A–P movement ranged between +7.5 and −8.5 mm, with five canals moving anteriorly, three posteriorly, and four in a mixed fashion. This study has shown the variability of canal movement relative to the concha and does not support previous reports that suggest that the ear canal only widens with jaw opening.
Publisher: Informa UK Limited
Date: 22-04-2018
Publisher: Elsevier BV
Date: 04-2010
Start Date: 1997
End Date: 1997
Funder: University of Tasmania
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: University of Sydney
View Funded ActivityStart Date: 2014
End Date: 2017
Funder: Forest & Wood Products Australia Limited
View Funded ActivityStart Date: 2010
End Date: 2012
Funder: Hydro Tasmania
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: Forest & Wood Products Australia Limited
View Funded ActivityStart Date: 2017
End Date: 2018
Funder: Interpine Group Limited
View Funded ActivityStart Date: 2018
End Date: 2018
Funder: Indufor Asia Pacific Limited
View Funded ActivityStart Date: 2010
End Date: 2012
Funder: Australian Research Council
View Funded ActivityStart Date: 2006
End Date: 2008
Funder: Hydro Electric Corporation
View Funded ActivityStart Date: 2006
End Date: 2008
Funder: Australian Research Council
View Funded ActivityStart Date: 2003
End Date: 2005
Funder: Australian Research Council
View Funded ActivityStart Date: 2003
End Date: 2005
Funder: Hydro Electric Corporation
View Funded Activity