153 results on '"Forsyth, David"'
Search Results
102. Improving animal welfare in wildlife shooting: The importance of projectile energy.
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Hampton, Jordan O., Adams, Peter J., Forsyth, David M., Cowled, Brendan D., Stuart, Ivor G., Hyndman, Tim H., and Collins, Teresa
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ANIMAL welfare , *KINETIC energy , *EUROPEAN rabbit , *THERMAL imaging cameras , *ACQUISITION of data - Abstract
ABSTRACT In wildlife shooting programs, the energy profile of the projectile or bullet (i.e., kinetic energy transferred to the animal), as distinct from caliber (projectile diameter), is an important factor for animal welfare. We examined the role of projectile energy in determining animal welfare outcomes for a typical European rabbit ( Oryctolagus cuniculus) sharpshooting program. We compared 2 projectiles of different energy profiles: low-energy 40-grain .22 long rifle rimfire (.22LR; 198 J) bullets and high-energy 40-grain .222 Remington® centerfire (.222R; 1,433 J) bullets, fired under similar conditions on 3 nights in September 2014, on a livestock grazing property near Broken Hill, New South Wales, southeastern Australia. We used a thermal-imaging camera to collect antemortem data from 500 rabbits that were shot at varying distance. We collected postmortem data via visual inspection from 482 rabbits that were killed. We used these data to compare 3 animal welfare parameters: wounding rate, duration of suffering, and ballistic injuries. We then used regression modeling to measure the effect of projectile type on these welfare parameters while accounting for shooting distance. All animal welfare parameters indicated that .222R projectiles were more humane than .22LR projectiles. When controlling for distance, for rabbits shot with a .22LR compared with a .222R, the odds of nonlethal wounding increased by a factor of 8 and noninstantaneous death increased by a factor of 9. All animal welfare parameters declined with increasing distance for both projectiles. Our results show that projectile energy and shooting distance were critical determinants of animal welfare outcomes in wildlife shooting programs. © 2016 The Wildlife Society. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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103. Dingoes can help conserve wildlife and our methods can tell.
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Nimmo, Dale G., Watson, Simon J., Forsyth, David M., Bradshaw, Corey J. A., and Frair, Jacqueline
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WILDLIFE conservation , *WILDLIFE management , *CONSERVATION biology , *DINGO , *TOP predators , *ENVIRONMENTAL monitoring , *ANIMAL behavior - Abstract
Management of apex predators is among the most controversial wildlife management issues globally. In Australia, some ecologists have advocated using the dingo, Canis dingo, as a tool for conservation management, due to evidence that they suppress invasive mesopredators., Hayward & Marlow ( Journal of Applied Ecology, 51, 2014 and 835) questioned the capacity of dingoes to provide benefits to native biodiversity due to their inability to eradicate foxes and cats. They also argued that indices of abundance commonly used in studies of mesopredator release by dingoes (namely, track-based indices) invalidate the conclusions of the studies. Hayward & Marlow caution conservation practitioners against incorporating dingoes into conservation programmes., Counter to their claims, we summarise research showing that the suppression of invasive mesopredators (cf. eradication) can enhance populations of native species and is therefore a meaningful conservation objective. We highlight literature supporting the hypothesis that dingoes suppress mesopredator abundance and activity, which in turn benefits native biodiversity., We show that Hayward & Marlow overlook many studies of carnivores that show track indices capture a large amount of the variation in the density of medium- and large-sized carnivores., Synthesis and applications. Practitioners cannot afford to wait to act given the perilous state of Australia's mammal species, and we argue that the evidence is sufficiently strong to justify managing dingoes for biodiversity conservation. [ABSTRACT FROM AUTHOR]
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- 2015
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104. Long-term and large-scale control of the introduced red fox increases native mammal occupancy in Australian forests.
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Robley, Alan, Gormley, Andrew M., Forsyth, David M., and Triggs, Barbara
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FORESTS & forestry , *PREDATION , *RED fox , *BIOLOGICAL invasions , *SPECIES diversity - Abstract
Management agencies commonly control non-native mammalian predators to protect native prey populations, but there are few robust examples of such control enhancing native prey populations. We conducted a 9-year landscape-scale management experiment to evaluate the benefits of controlling the invasive red fox ( Vulpes vulpes ) to low densities for three native ground-dwelling mammalian prey species—common brushtail possum ( Trichosurus vulpecula ), long-nosed potoroo ( Potorous tridactylus ) and southern brown bandicoot ( Isoodon obesulus )—in south-east Australian forests. We hypothesized that sustained and spatially extensive fox control would reduce fox abundance and increase occupancy, colonization and persistence rates for all three prey species in three treatment areas relative to three non-treatment areas. There was a substantial decline in bait take by foxes in treatment areas from 2005 to 2013, and fox abundances were much lower in treatment than non-treatment areas throughout the experiment. Occupancy rates of all three native prey species increased in treatment areas relative to non-treatment areas, although the magnitude of the increase varied with species, treatment area, and time. Colonization and persistence rates were not always positive for all species and all treatment areas. Our experiment demonstrates that foxes can be reduced to, and maintained at, low abundances and that this has a generally positive effect on the occupancy by small native mammalian prey species. [ABSTRACT FROM AUTHOR]
- Published
- 2014
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105. Four-wave mixing analyses for future ultrafast wavelength conversion at 0.64 Tb/s in a semiconductor optical amplifier.
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Kharraz, Osayd M., Ahmad, Harith, Forsyth, David I., Dernaika, Mohamad, Mohammad, Abu Bakar B., Zulkifli, Mohd Zamani B., Ismail, Mohd Faizal B., and Mohd Supa'at, Abu Sahmah B.
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SEMICONDUCTOR optical amplifiers , *WAVELENGTHS , *BIT error rate , *NONLINEAR optics , *OPTICAL amplifiers - Abstract
This paper describes numerical and analytical analyses relating to the use of nonlinear four-wave mixing in a semiconductor optical amplifier medium for anticipated wavelength conversion at ultrahigh data rates of 320 and 640 Gb/s. The proposed system guidelines and design show that a maximum wavelength shift of 30 nm can be achieved at 640 Gb/s, while still maintaining an acceptable bit error rate. In addition, the impact of the pump-probe ratio and semiconductor optical amplifier bias current are investigated and the results are reported. [ABSTRACT FROM AUTHOR]
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- 2014
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106. All-incoherent wavelength conversion in highly nonlinear fiber using four-wave mixing.
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Kharraz, Osayd M., Ahmad, Harith, Forsyth, David I., Dernaika, Mohamad, Zulkifli, Mohd Zamani B., Ismail, Mohd Faizal B., and Mohammad, Abu Bakar B.
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WAVELENGTHS , *FIBER optics , *BRAGG gratings , *LIGHT filters , *SIGNAL-to-noise ratio , *OPTICAL polarization - Abstract
This work describes efficient and polarization insensitive, all-incoherent four-wave mixing wavelength conversion achieved within a short length of highly nonlinear fiber medium, created by using both spectrally sliced pump and probe channels from a single-amplified spontaneous emission source coupled to two narrow-band Fiber Bragg grating (FBG) filters. This simple and cost-effective scheme is capable of generating a down-converted probe channel across a 17.2-nm wavelength span, while still maintaining a high conversion efficiency of around -22 dB and an optical-signal-to-noise ratio of ~21 dB. The effects of pump power, FBG detuning, and polarization are also reported. [ABSTRACT FROM AUTHOR]
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- 2014
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107. Enhanced image processing methods for GMR array inspections of multilayer metallic structures.
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Aldrin, John C., Motes, Doyle, Forsyth, David S., and Steffes, Gary
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IMAGE processing , *MAGNETORESISTANCE , *ENGINEERING inspection , *DETECTORS , *FATIGUE crack growth , *FASTENERS , *ALGORITHMS - Abstract
The objective of this paper is to present a comprehensive approach to image processing for Giant Magnetoresistive (GMR) array sensors with sheet current sources for the inspection of fatigue cracks in complex metallic structures. The approach incorporates optimal phase angle adjustment, array sensitivity compensation, fastener site identification, an adaptive edge evaluation and removal algorithm and a classification metric. Processing examples are presented that highlight the benefits of these algorithms for improving crack detection for challenging edge and fastener spacing conditions. [ABSTRACT FROM AUTHOR]
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- 2013
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108. Detection and Characterisation of an Endogenous Betaretrovirus in Australian Wild Deer.
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Huaman, Jose L., Pacioni, Carlo, Forsyth, David M., Pople, Anthony, Hampton, Jordan O., Carvalho, Teresa G., and Helbig, Karla J.
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FALLOW deer , *ENDOGENOUS retroviruses , *RETROVIRUS diseases , *GENOMICS , *INTRODUCED species , *DEER - Abstract
Endogenous retroviruses (ERVs) are the remnants of past retroviral infections that once invaded the host's germline and were vertically transmitted. ERV sequences have been reported in mammals, but their distribution and diversity in cervids are unclear. Using next-generation sequencing, we identified a nearly complete genome of an endogenous betaretrovirus in fallow deer (Dama dama). Further genomic analysis showed that this provirus, tentatively named cervid endogenous betaretrovirus 1 (CERV β1), has typical betaretroviral genome features (gag-pro-pol-env) and the betaretrovirus-specific dUTPase domain. In addition, CERV β1 pol sequences were detected by PCR in the six non-native deer species with wild populations in Australia. Phylogenetic analyses demonstrated that CERV β1 sequences from subfamily Cervinae clustered as sister taxa to ERV-like sequences in species of subfamily Muntiacinae. These findings, therefore, suggest that CERV β1 endogenisation occurred after the split of these two subfamilies (between 3.3 and 5 million years ago). Our results provide important insights into the evolution of betaretroviruses in cervids. [ABSTRACT FROM AUTHOR]
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- 2022
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109. Video Event Detection: From Subvolume Localization to Spatiotemporal Path Search.
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Tran, Du, Yuan, Junsong, and Forsyth, David
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SPATIOTEMPORAL processes , *OBJECT recognition (Computer vision) , *SEARCH algorithms , *VIDEO compression , *ROBUST control - Abstract
Although sliding window-based approaches have been quite successful in detecting objects in images, it is not a trivial problem to extend them to detecting events in videos. We propose to search for spatiotemporal paths for video event detection. This new formulation can accurately detect and locate video events in cluttered and crowded scenes, and is robust to camera motions. It can also well handle the scale, shape, and intraclass variations of the event. Compared to event detection using spatiotemporal sliding windows, the spatiotemporal paths correspond to the event trajectories in the video space, thus can better handle events composed by moving objects. We prove that the proposed search algorithm can achieve the global optimal solution with the lowest complexity. Experiments are conducted on realistic video data sets with different event detection tasks, such as anomaly event detection, walking person detection, and running detection. Our proposed method is compatible with different types of video features or object detectors and robust to false and missed local detections. It significantly improves the overall detection and localization accuracy over the state-of-the-art methods. [ABSTRACT FROM PUBLISHER]
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- 2014
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110. Guest Editors' Introduction to the Special Section on Computational Photography.
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Chakrabarti, Ayan, Sunkavalli, Kalyan, and Forsyth, David A.
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COMPUTATIONAL photography , *OPTICAL flow , *ARTIFICIAL intelligence , *PIXELS , *COMPUTER graphics - Abstract
An introduction is presented in which the editor discusses articles in the issue on the topics including introduce novel computational methods that exploit non-traditional sensors; propose novel sensors and acquisition systems; and leverage visual measurements made by unconventional sensors.
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- 2020
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111. Learning Image Similarity from Flickr Groups Using Fast Kernel Machines.
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Wang, Gang, Hoiem, Derek, and Forsyth, David
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IMAGE processing , *MACHINE learning , *SUPPORT vector machines , *HISTOGRAMS , *KERNEL functions , *FEATURE extraction , *EUCLIDEAN distance - Abstract
Measuring image similarity is a central topic in computer vision. In this paper, we propose to measure image similarity by learning from the online Flickr image groups. We do so by: Choosing 103 Flickr groups, building a one-versus-all multiclass classifier to classify test images into a group, taking the set of responses of the classifiers as features, calculating the distance between feature vectors to measure image similarity. Experimental results on the Corel dataset and the PASCAL VOC 2007 dataset show that our approach performs better on image matching, retrieval, and classification than using conventional visual features. To build our similarity measure, we need one-versus-all classifiers that are accurate and can be trained quickly on very large quantities of data. We adopt an SVM classifier with a histogram intersection kernel. We describe a novel fast training algorithm for this classifier: the Stochastic Intersection Kernel MAchine (SIKMA) training algorithm. This method can produce a kernel classifier that is more accurate than a linear classifier on tens of thousands of examples in minutes. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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112. Estimates of maximum annual population growth rates ( rm) of mammals and their application in wildlife management.
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Hone, Jim, Duncan, Richard P., and Forsyth, David M.
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ANIMAL populations , *WILDLIFE management , *ANIMAL population estimates , *WILDLIFE census , *WILDLIFE conservation , *ANIMAL ecology , *POPULATION biology , *BAYESIAN field theory - Abstract
1. The maximum annual population growth rate ( rm) is a critical parameter in many models of wildlife dynamics and management. An important application of rm is the estimation of the maximum proportion of a population that can be removed to stop population growth ( p). 2. When rm cannot be estimated in the field, one option is to estimate it from demographic data. We evaluate the use of the relationship between rm and female age at first reproduction (α), which is independent of phylogeny, to estimate rm. We first demonstrate that the relationship between field and demographic estimates of rm is unbiased. We then show that the relationship provides an unbiased and simple method to estimate rm using data for 64 mammal species. We also show that p declines exponentially as α increases. 3. We use the fitted relationship to estimate annual rm and p for 55 mammal species in Australia and New Zealand for which there are no field estimates of rm. The estimates differ by species but have low precision (wide 95% credible intervals CIs). Our estimate of rm for the Tasmanian devil Sarcophilus harrisii is high (0·6, 95% CI: 0·05–2·39) and suggests devils would become extinct if >0·34 of the population is removed annually (e.g. by facial tumour disease). Our estimate of rm (0·77, 95% CI: 0·71–1·05) for brushtail possum Trichosurus vulpecula is much greater than published estimates and highlights the need for further field estimates of rm for the species in New Zealand. 4. Synthesis and applications. Since rm has not been estimated in the field for the majority of mammal species, our approach enables estimates with credible intervals for this important parameter to be obtained for any species for which female age at first reproduction is known. However, the estimates have wide ... [ABSTRACT FROM AUTHOR]
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- 2010
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113. Quantifying Surface Deformation With the Edge of Light-Enhanced Visual Inspection.
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Zheng Liu, Genest, Marc, Forsyth, David S., and Marincak, Anton
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PREDICATE calculus , *MULTIPHASE flow , *TWO-phase flow , *PROTOTYPES , *INDUSTRIAL lasers , *PHYSICAL measurements - Abstract
Edge of Light (EOL) is a rapid enhanced visual inspection technique developed by the Institute for Aerospace Research, National Research Council Canada. One application of interest is the inspection of aircraft lap joints for pillowing deformation caused by hidden corrosion. The EOL technique provides an intuitive result, which is a representation of surface topography. However, a quantitative interpretation of the inspection results is still a challenge. In this paper, the quantification of surface deformation is investigated by using a laser-displacement sensor as a calibration tool. A procedure that implements the reconstruction of the deformed surface from EOL scanning is proposed. Experimental results obtained from a pillowing simulator and a service-retired aircraft lap joint are presented in this paper to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]
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- 2009
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114. Synthesis, characterization and electrochemistry of bis(3-aryl-6,6-dimethylcyclohexadienyl)ruthenium complexes
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Kirss, Rein U., Henriksen, Alexandra, Forsyth, David A., and Feighery, William
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INDUSTRIAL chemistry , *PLATINUM group , *ETHANES , *TRANSITION metals - Abstract
Abstract: Five bis(3-aryl-6,6-dimethylcyclohexadienyl)ruthenium complexes (4a–4e) are prepared by reactions between di-μ-chlorodichlorobis[(1–3η:6–8η)-2,7-dimethyl-octadienyl]diruthenium and the corresponding dienes. The larger aryl substituents increase the barrier to rotation in 4a–4e relative to bis(3-methyl-6,6-cyclohexadienyl)ruthenium (5b). The activation parameters were determined by line-shape analysis for the exchange process in 4a: ΔG † (183K), 8.0±0.2kcal/mol; ΔH †, 10.3kcal/mol; and ΔS †, 13cal/mol/K. The electronic effect of the aryl substituents on the cyclohexadienyl ligand on the oxidation potential of the complex are compared to the effect of methyl substituents. [Copyright &y& Elsevier]
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- 2006
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115. Adaptive Management Experiments in Vertebrate Pest Control in New Zealand and Australia.
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Parkes, John P., Robley, Alan, Forsyth, David M., and Choquenot, David
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WILDLIFE management , *RED fox , *WILDLIFE managers , *PEST control - Abstract
Government conservation agencies in New Zealand and the Australian state of Victoria spend 20% and 4%, respectively, of their annual budgets to manage a small part of the problem caused by introduced mammals. Managers' uncertainty about the optimal strategies for applying pest control has led to major differences in management practices within the single pest control programs in both countries. Monitoring under a trial-and-error approach has not removed uncertainty but has led managers to support the application of adaptive management for their pest control Control of brushtail possums (Trichosurus vulpecula) in New Zealand and red foxes (Vulpes vulpes) in Victoria, Australia, is conducted over large areas in many operations, but individual managers apply different control regimes based on the perceived benefits and opportunity costs. We report on the processes used to set up the first adaptive management experiments in pest control in New Zealand or Australia that combine the competing models approach (used when only a single management regime can be applied at one time) with an experimental approach (made possible when different management regimes are applied simultaneously in different places) with the aim of elucidating benefits and costs of the different strategies used to control the 2 pests. [ABSTRACT FROM AUTHOR]
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- 2006
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116. Matching Words and Pictures.
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Barnard, Kobus, Duygulu, Pinar, Forsyth, David, de Freitas, Nando, Beli, David M., and Jordan, Michael I.
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IMAGE processing , *MACHINE learning - Abstract
We present a new approach for modeling multi-modal data sets, focusing on the specific case of segmented images with associated text. Learning the joint distribution of image regions and words has many applications. We consider in detail predicting words associated with whole images (auto-annotation) and corresponding to particular image regions (region naming). Auto-annotation might help organize and access large collections of images. Region naming is a model of object recognition as a process of translating image regions to words, much as one might translate from one language to another. Learning the relationships between image regions and semantic correlates (words) is an interesting example of multi-modal data mining, particularly because it is typically hard to apply data mining techniques to collections of images. We develop a number of models for the joint distribution of image regions and words, including several which explicitly learn the correspondence between regions and words. We study multi-modal and correspondence extensions to Hofmann's hierarchical clustering/aspect model, a translation model adapted from statistical machine translation (Brown et al.), and a multi-modal extension to mixture of latent Dirichlet allocation (MoM-LDA). All models are assessed using a large collection of annotated images of real scenes. We study in depth the difficult problem of measuring performance. For the annotation task, we look at prediction performance on held out data. We present three alternative measures, oriented toward different types of task. Measuring the performance of correspondence methods is harder, because one must determine whether a word has been placed on the right region of an image. We can use annotation performance as a proxy measure, but accurate measurement requires hand labeled data, and thus must occur on a smaller scale. We show results using both an annotation proxy, and manually labeled data. [ABSTRACT FROM AUTHOR]
- Published
- 2003
117. Factors Preventing the Recovery of New Zealand Forests Following Control of Invasive Deer.
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Coomes, David A., Allen, Robert B., Forsyth, David M., and Lee, William G.
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BIOTIC communities - Abstract
There is currently great interest in restoring ecosystems affected by invasive organisms. In New Zealand, deer were introduced during the nineteenth century, causing dramatic changes to the understory composition and structure of some forests. Deer prefer to browse on short tree species, mostly associated with early successional stands and moist-fertile sites, but many tall tree species are browsed only when other food sources are scarce. The government has invested heavily in control programs aimed at reducing deer numbers and thereby restoring forests to something approaching their preinvasion composition and structure, but have met with only limited success. Based on a literature review, we give several examples of situations in which deer impacts may not be reversible, including the following: (1) palatable species remaining highly browsed even at low deer densities as a result of diet switching; (2) occupation of vacated niches by plant species not eaten by deer; (3) local extinction of seed sources; (4) fundamental alterations to successional pathways; (5) shifts in ecosystem processes; (6) other exotic animals becoming naturalized and weakening the effectiveness of single-species control; and (7) exotic plants weakening the effectiveness of single-species control. We consider the contributions that scientific research can make to effective forest restoration, including empirically based forest-dynamics models that place regeneration in the context of other processes, such as disturbance, soil fertility, and multiple invasive organisms. [ABSTRACT FROM AUTHOR]
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- 2003
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118. Fun with Computational Chemistry: Solving Spectral Problems Using Computed [sub 13]C NMR Chemical Shifts. A Comparison of Empirical and Quantum Mechanical Methods.
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Tilley, Leon J., Prevoir, Shawn J., and Forsyth, David A.
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MOLECULAR orbitals , *CHEMISTRY - Abstract
Analyzes the use of molecular orbit shift in computational chemistry. Comparison between empirical and quantum mechanical methods; Efforts to improve the problem-solving component of the advanced undergraduate spectroscopy course; Application of spectroscopy in forensic and environmental science.
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- 2002
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119. High predictability in introduction outcomes and the geographical range size of introduced Australian birds: a role for climate.
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Duncan, Richard P., Bomford, Mary, Forsyth, David M., and Conibear, Louise
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BIRDS , *HABITATS , *ECOLOGICAL assessment - Abstract
Summary 1.We investigated factors hypothesized to influence introduction success and subsequent geographical range size in 52 species of bird that have been introduced to mainland Australia. 2.The 19 successful species had been introduced more times, at more sites and in greater overall numbers. Relative to failed species, successfully introduced species also had a greater area of climatically suitable habitat available in Australia, a larger overseas range size and were more likely to have been introduced successfully outside Australia. After controlling for phylogeny these relationships held, except that with overseas range size and, in addition, larger-bodied species had a higher probability of introduction success. There was also a marked taxonomic bias: gamebirds had a much lower probability of success than other species. A model including five of these variables explained perfectly the patterns in introduction success across-species. 3.Of the successful species, those with larger geographical ranges in Australia had a greater area of climatically suitable habitat, traits associated with a faster population growth rate (small body size, short incubation period and more broods per season) and a larger overseas range size. The relationships between range size in Australia, the extent of climatically suitable habitat and overseas range size held after controlling for phylogeny. 4.We discuss the probable causes underlying these relationships and why, in retrospect, the outcome of bird introductions to Australia are highly predictable. [ABSTRACT FROM AUTHOR]
- Published
- 2001
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120. Long-term fertility control reduces overabundant koala populations and mitigates their impacts on food trees.
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Ramsey, David S.L., Watters, Freyja, Forsyth, David M., Wood, Matthew, Todd, Charles R., Molsher, Robyn, and Cassey, Phillip
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BIRTH control , *KOALA , *MAMMAL populations , *CATTLE fertility , *FOOD prices , *PLANT communities , *POPULATION density - Abstract
Overabundant herbivorous mammals can increase the mortality rates of preferred food species, causing long-term changes to plant communities. When lethal control of the herbivore is not possible, fertility control is often advocated as a management solution. There is, however, little empirical evidence that fertility control is a viable option for managing the impacts of open populations of polygynous mammals. We evaluated the effectiveness of two long-term fertility control programs implemented to reduce overabundant koala (Phascolarctos cinereus) populations and their impacts on preferred food trees (manna gum, Eucalyptus viminalis): one in Victoria (10 years) and one in South Australia (17 years). Fertility control reduced koala recruitment such that population densities more than halved at both sites. Mortality rates of manna gum trees were significantly reduced at one site, and trees with light or moderate defoliation recovered at both sites. Relationships between koala population density and canopy defoliation suggest that if management wishes to alleviate moderate browsing pressure then koala density should be maintained below 1.0 koala/ha. We conclude that population-level fertility control can significantly reduce overabundant koala populations and some of their impacts on food trees. Our empirical study demonstrates that long-term fertility control can reduce the undesirable impacts of open populations of polygynous mammals. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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121. Serosurveillance and Molecular Investigation of Wild Deer in Australia Reveals Seroprevalence of Pestivirus Infection.
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Huaman, Jose L., Pacioni, Carlo, Forsyth, David M., Pople, Anthony, Hampton, Jordan O., Carvalho, Teresa G., and Helbig, Karla J.
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PESTIVIRUS diseases , *DEER , *DOMESTIC animals , *VIRUS diseases , *HEMORRHAGIC diseases , *SEROPREVALENCE , *BOVINE viral diarrhea virus - Abstract
Since deer were introduced into Australia in the mid-1800s, their wild populations have increased in size and distribution, posing a potential risk to the livestock industry, through their role in pathogen transmission cycles. In comparison to livestock, there are limited data on viral infections in all wildlife, including deer. The aim of this study was to assess blood samples from wild Australian deer for serological evidence of exposure to relevant viral livestock diseases. Blood samples collected across eastern Australia were tested by ELISA to detect antigens and antibodies against Pestivirus and antibodies against bovine herpesvirus 1. A subset of samples was also assessed by RT-PCR for Pestivirus, Simbu serogroup, epizootic hemorrhagic disease virus and bovine ephemeral fever virus. Our findings demonstrated a very low seroprevalence (3%) for ruminant Pestivirus, and none of the other viruses tested were detected. These results suggest that wild deer may currently be an incidental spill-over host (rather than a reservoir host) for Pestivirus. However, deer could be a future source of viral infections for domestic animals in Australia. Further investigations are needed to monitor pathogen activity and quantify possible future infectious disease impacts of wild deer on the Australian livestock industry. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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122. A review of the damage caused by invasive wild mammalian herbivores to primary production in New Zealand.
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Latham, A. David M., Latham, M. Cecilia, Norbury, Grant L., Forsyth, David M., and Warburton, Bruce
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HERBIVORES , *EUROPEAN rabbit , *FALLOW deer , *PEST control , *KNOWLEDGE gap theory , *ECONOMIC impact , *INVASIVE candidiasis , *PASTURE management - Abstract
Wild mammalian herbivores can compete with domestic livestock and damage other types of production systems. We reviewed damage by wild mammalian herbivores, excluding rodents, to primary production in New Zealand and assessed whether primary producers alter stocking rates in response to changes in forage availability following pest control. Given the dearth of information on the damage caused by wild mammalian herbivores to many production systems, we primarily focused on their damage to agriculture. With the exception of the substantial damage that brushtail possums (Trichosurus vulpecula) and European rabbits (Oryctolagus cuniculus) cause, there are no quantitative estimates of pasture depletion by other wild mammalian herbivores on New Zealand farmland. Estimates of dry matter consumption by wild mammalian herbivores, converted to stock unit equivalents, suggest that several species can substantially reduce stocking rates when they occur on farmland. Quantitative data on the damage they cause to horticulture and silviculture are lacking, but damage to coniferous seedlings has been recorded for possums, wallabies (Notamacropus spp.), and some species of deer (Cervus spp., Rusa spp., and Dama dama). The process that primary producers use to decide whether to control wild mammalian herbivores includes complex social and economic factors, but quantitative information is important for weighing up the expected costs and benefits of pest control. However, it is unclear how primary producers manage livestock in response to increases in forage availability following pest control. The paucity of quantitative data on wild mammalian herbivore damage to production assets is a substantial knowledge gap. Key research priorities are (i) understanding how damage varies with pest density (critical information for effective pest management) and (ii) and how primary producers alter stocking rates following reductions in pest density. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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123. A refined model of body mass and population density in flightless birds reconciles extreme bimodal population estimates for extinct moa.
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Latham, A. David M., Latham, M. Cecilia, Wilmshurst, Janet M., Forsyth, David M., Gormley, Andrew M., Pech, Roger P., Perry, George L. W., and Wood, Jamie R.
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POPULATION density , *ANIMAL population density , *BIRDS , *PARAMETERS (Statistics) , *NUMBERS of species , *ESTIMATES - Abstract
Flightless birds were once the largest and heaviest terrestrial fauna on many archipelagos around the world. Robust approaches for estimating their population parameters are essential for understanding prehistoric insular ecosystems and extinction processes. Body mass and population density are negatively related for extant flightless bird species, providing a method for quantifying densities and population sizes of extinct flightless species. Here we assemble an updated global data set of body mass and population densities for extant flightless birds and estimate the relationship between these variables. We use generalised least squares models that account for phylogenetic relatedness and incorporate the effects of limiting factors (e.g. habitat suitability) on population density. We demonstrate the applicability of this allometric relationship to extinct species by estimating densities for each of the nine species of moa (Dinornithiformes) and generating a combined spatially explicit map of total moa density across New Zealand. To compare our density estimates with those previously published, we summed individual species' abundances to generate a mean national density of 2.02–9.66 birds km−2 for low‐ and high‐density scenarios, respectively. Our results reconcile the extreme bimodality of previous estimates (< 2 birds km−2 and > 10 birds km−2) and are comparable to contemporary densities of large herbivorous wild mammals introduced into New Zealand about 150 yr ago. The revised moa density has little effect on the harvest rates required to bring about extinction within 150–200 yr, indicating that rapid extinction was an inevitable response to human hunting, irrespective of the initial population of moa. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
124. Emerging RHDV2 suppresses the impact of endemic and novel strains of RHDV on wild rabbit populations.
- Author
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Ramsey, David S. L., Cox, Tarnya, Strive, Tanja, Forsyth, David M., Stuart, Ivor, Hall, Robyn, Elsworth, Peter, Campbell, Susan, and Knutie, Sarah
- Subjects
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RABBITS , *EUROPEAN rabbit , *VIRUS diseases , *AUSTRALIANS ,RABBIT diseases - Abstract
Multi‐strain, host‐disease dynamics describe a system where multiple strains of a pathogen compete for susceptible individuals of a single host. The theoretical properties of these systems have been well studied, but there are few empirical studies in wildlife hosts.We examined the impacts of two novel strains of rabbit haemorrhagic disease virus (RHDV) recently introduced into Australia, one inadvertently (RHDV2) and one deliberately for rabbit biocontrol (RHDV‐K5), by analysing long‐term monitoring data for introduced European rabbits Oryctolagus cuniculus from 18 sites throughout Australia. We examined population‐level impacts using rabbit spotlight counts pre‐ and post‐arrival of the two strains. We also analysed serological data to determine potential interactions among the introduced and existing field strains of RHDV, as well as a pre‐existing benign strain of calicivirus (RCV‐A1).Serological analyses suggested that RHDV2 arrived in Australia during spring 2014 and spread rapidly through the Australian rabbit population within 2 years. Following the establishment of RHDV2, rabbit abundance was reduced by an average of 60%, with impacts most pronounced in South and Western Australia. In contrast, the deliberate release of RHDV‐K5 had little impact on rabbit populations.Although RHDV2 has spread rapidly throughout Australia, our serological analyses do not support the observation that RHDV2 is rapidly replacing existing field strains of RHDV, as was previously reported in Australia and Europe. Nevertheless, RHDV2 has negatively impacted the ability of RHDV and RCV‐A1 to spread within rabbit populations, most likely due to its ability to infect juvenile rabbits, thereby removing them from the pool of susceptible individuals available to be infected by competing strains.Synthesis and applications. The impact of the release of a novel strain of rabbit haemorrhagic disease virus (RHDV‐K5) for rabbit biocontrol in Australia has been suppressed by the emergence of a competing strain, RHDV2. Hence, the success of further releases of similar RHDV strains for rabbit biocontrol appears doubtful. Despite this, RHDV2 has suppressed rabbit abundances by an average of 60%, with impacts most pronounced in South and Western Australia. Whether the incursion of RHDV2 leads to the competitive exclusion of other endemic RHDV strains remains to be resolved. However, the existence of partial cross‐immunity could allow some level of coexistence between RHDV2 and RHDV strains, at least in the medium term. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
125. B-scan technique for localization and characterization of fatigue cracks around fastener holes in multi-layered structures.
- Author
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Hopkins, Deborah, Datuin, Marvin, Aldrin, John, Warchol, Mark, Warchol, Lyudmila, Forsyth, David, Chimenti, Dale E., and Bond, Leonard J.
- Subjects
- *
FASTENERS , *FRACTURE of joints (Engineering) , *TESTING of joints (Engineering) , *FRACTURE mechanics , *NONDESTRUCTIVE testing , *ULTRASONIC testing , *MATERIAL fatigue , *SERVICE life - Abstract
The work presented here aims to develop and transition angled-beam shear-wave inspection techniques for crack localization at fastener sites in multi-layer aircraft structures. This requires moving beyond detection to achieve reliable crack location and size, thereby providing invaluable information for maintenance actions and service-life management. The technique presented is based on imaging cracks in “True” B-scans (depth view projected in the sheets along the beam path). The crack traces that contribute to localization in the True B-scans depend on small, diffracted signals from the crack edges and tips that are visible in simulations and experimental data acquired with sufficient gain. The most recent work shows that cracks rotated toward and away from the central ultrasonic beam also yield crack traces in True B-scans that allow localization in simulations, even for large obtuse angles where experimental and simulation results show very small or no indications in the C-scans. Similarly, for two sheets joined by sealant, simulations show that cracks in the second sheet can be located in True B-scans for all locations studied: cracks that intersect the front or back wall of the second sheet, as well as relatively small mid-bore cracks. These results are consistent with previous model verification and sensitivity studies that demonstrate crack localization in True B-scans for a single sheet and cracks perpendicular to the ultrasonic beam. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
126. Continental patterns in the diet of a top predator: Australia's dingo.
- Author
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Doherty, Tim S., Davis, Naomi E., Dickman, Chris R., Forsyth, David M., Letnic, Mike, Nimmo, Dale G., Palmer, Russell, Ritchie, Euan G., Benshemesh, Joe, Edwards, Glenn, Lawrence, Jenny, Lumsden, Lindy, Pascoe, Charlie, Sharp, Andy, Stokeld, Danielle, Myers, Cecilia, Story, Georgeanna, Story, Paul, Triggs, Barbara, and Venosta, Mark
- Subjects
- *
ANIMALS , *LIVESTOCK productivity , *BIOGEOGRAPHY , *ORYCTOLAGUS , *BIOCLIMATOLOGY - Abstract
Conserving large carnivores is controversial because they can threaten wildlife, human safety, and livestock production. Since large carnivores often have large ranges, effective management requires knowledge of how their ecology and functional roles vary biogeographically.We examine continental‐scale patterns in the diet of the dingo – Australia's largest terrestrial mammalian predator. We describe and quantify how dingo dietary composition and diversity vary with environmental productivity and across five bioclimatic zones: arid, semi‐arid, tropical, sub‐tropical, and temperate.Based on 73 published and unpublished data sets from throughout the continent, we used multivariate linear modelling to assess regional trends in the occurrence of nine food groups (arthropods, birds, reptiles, European rabbits Oryctolagus cuniculus, medium‐sized [25–125 kg] and large [169–825 kg] exotic ungulates [including livestock], and other small [<0.5 kg], medium‐sized [0.5–6.9 kg] and large [≥7 kg] mammals) in dingo diets. We also assessed regional patterns in the dietary occurrence of livestock and the relationship between dietary occurrence of rabbits and small, medium‐sized and large mammals.Dingoes eat at least 229 vertebrate species (66% mammals, 22% birds, 11% reptiles, and 1% other taxa). Dietary composition varied across bioclimatic zones, with dingo diets in the arid and semi‐arid zones (low‐productivity sites) having the highest occurrence of arthropods, reptiles, birds, and rabbits. Medium‐sized mammals occurred most frequently in temperate and sub‐tropical zone diets (high‐productivity sites), large mammals least in the arid and sub‐tropical zones, and livestock most in the arid and tropical zones. The frequency of rabbits in diets was negatively correlated with that of medium‐sized, but not small or large mammals.Dingoes have a flexible and generalist diet that differs among bioclimatic zones and with environmental productivity in Australia. Future research should focus on examining how dingo diets are affected by local prey availability and human‐induced changes to prey communities. [ABSTRACT FROM AUTHOR]
- Published
- 2019
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127. An Approximate Shading Model with Detail Decomposition for Object Relighting.
- Author
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Zhang, Hongyi, Liao, Zicheng, Karsch, Kevin, and Forsyth, David
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- *
IMAGE , *EXAMPLE , *OBJECT (Philosophy) , *EVALUATION , *RESEARCH - Abstract
We present an object relighting system that allows an artist to select an object from an image and insert it into a target scene. Through simple interactions, the system can adjust illumination on the inserted object so that it appears naturally in the scene. To support image-based relighting, we build object model from the image, and propose a perceptually-inspired approximate shading model for the relighting. It decomposes the shading field into (a) a rough shape term that can be reshaded, (b) a parametric shading detail that encodes missing features from the first term, and (c) a geometric detail term that captures fine-scale material properties. With this decomposition, the shading model combines 3D rendering and image-based composition and allows more flexible compositing than image-based methods. Quantitative evaluation and a set of user studies suggest our method is a promising alternative to existing methods of object insertion. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
128. Exploring mechanisms and origins of reduced dispersal in island Komodo dragons.
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Jessop, Tim S., Ariefiandy, Achmad, Purwandana, Deni, Imansyah, Jeri, Ciofi, Claudio, Benu, Yunias Jackson, Fordham, Damien A., Forsyth, David M., Mulder, Raoul A., and Phillips, Benjamin L.
- Subjects
- *
KOMODO dragon , *BIOTIC communities , *NATURAL selection , *ANIMAL mechanics , *BIOTELEMETRY , *ANIMAL introduction - Abstract
Loss of dispersal typifies island biotas, but the selective processes driving this phenomenon remain contentious. This is because selection via, both indirect (e.g. relaxed selection or island syndromes) and direct (e.g. natural selection or spatial sorting) processes may be involved, and no study has yet convincingly distinguished between these alternatives. Here, we combined observational and experimental analyses of an island lizard, the Komodo dragon (Varanus komodoensis, the world's largest lizard), to provide evidence for the actions of multiple processes that could contribute to island dispersal loss. In the Komodo dragon, concordant results from telemetry, simulations, experimental translocations, mark-recapture, and gene flow studies indicated that despite impressive physical and sensory capabilities for long-distance movement, Komodo dragons exhibited near complete dispersal restriction: individuals rarely moved beyond the valleys they were born/captured in. Importantly, lizard site-fidelity was insensitive to common agents of dispersal evolution (i.e. indices of risk for inbreeding, kin and intraspecific competition, and low habitat quality) that consequently reduced survival of resident individuals. We suggest that direct selection restricts movement capacity (e.g. via benefits of spatial philopatry and increased costs of dispersal) alongside use of dispersal-compensating traits (e.g. intraspecific niche partitioning) to constrain dispersal in island species. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
129. Model Benchmarking and Reference Signals for Angled-beam Shear Wave Ultrasonic Nondestructive Evaluation (NDE) Inspections.
- Author
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Aldrin, John C., Hopkins, Deborah, Datuin, Marvin, Warchol, Mark, Warchol, Lyudmila, Forsyth, David S., Buynak, Charlie, and Lindgren, Eric A.
- Subjects
- *
NONDESTRUCTIVE testing , *SHEAR waves , *THEORY of wave motion , *STRUCTURAL plates , *SIGNAL processing - Abstract
For model benchmark studies, the accuracy of the model is typically evaluated based on the change in response relative to a selected reference signal. The use of a side drilled hole (SDH) in a plate was investigated as a reference signal for angled beam shear wave inspection for aircraft structure inspections of fastener sites. Systematic studies were performed with varying SDH depth and size, and varying the ultrasonic probe frequency, focal depth, and probe height. Increased error was observed with the simulation of angled shear wave beams in the near-field. Even more significant, asymmetry in real probes and the inherent sensitivity of signals in the near-field to subtle test conditions were found to provide a greater challenge with achieving model agreement. To achieve quality model benchmark results for this problem, it is critical to carefully align the probe with the part geometry, to verify symmetry in probe response, and ideally avoid using reference signals from the near-field response. Suggested reference signals for angled beam shear wave inspections include using the 'through hole' corner specular reflection signal and the full skip' signal off of the far wall from the side drilled hole. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
130. Localization and characterization of fatigue cracks around fastener holes using spherically focused ultrasonic probes.
- Author
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Hopkins, Deborah, Datuin, Marvin, Aldrin, John, Warchol, Mark, Warchol, Lyudmila, and Forsyth, David
- Subjects
- *
FATIGUE crack growth , *SIGNAL processing , *CYCLIC loads , *CRACK propagation (Fracture mechanics) , *SHEAR waves - Abstract
Results are presented from laboratory experiments and simulations that demonstrate the ability to localize fatigue cracks around fastener holes using spherically focused ultrasonic probes for shear-wave inspections. For the experiments, fatigue cracks were created in aluminum plates in a testing frame under cyclic loading. With the exceptions of one specimen with a mid-bore crack and another with a "through" crack, the remaining specimens contain surface-breaking cracks. All of the specimens were inspected for the cracks intersecting the back wall, and some were flipped over and re-inspected with the crack intersecting the front surface. Parameter and variable sensitivity studies were performed using CIVA Simulation Software. In contrast to C-scans where detection and localization of small cracks can be very difficult, modeling and initial experimental results demonstrate that cracks can be accurately located in "True" B-scans (B-scans projected in the part along the beam path). Initial results show that small-amplitude diffracted/scattered signals from the crack tips and edges are essential in obtaining clear crack traces in the True B-scans. It is important therefore that experimental data be acquired with sufficient gain to capture the diffracted/scattered signals. In all of the cases studied here, saturating the high-amplitude specular reflections from the fastener hole and crack enhanced the crack trace in the True B-scans. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
131. Localization And Characterization of Fatigue Cracks Around Fastener Holes Using Spherically Focused Ultrasonic Probes.
- Author
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Hopkins, Deborah, Datuin, Marvin, Aldrin, John, Warchol, Mark, Warchol, Lyudmila, and Forsyth, David
- Subjects
- *
FATIGUE cracks , *FASTENERS , *ALUMINUM plates , *SIMULATION software , *ULTRASONIC equipment - Abstract
Results are presented from laboratory experiments and simulations that demonstrate the ability to localize fatigue cracks around fastener holes using spherically focused ultrasonic probes for shear-wave inspections. For the experiments, fatigue cracks were created in aluminum plates in a testing frame under cyclic loading. With the exceptions of one specimen with a mid-bore crack and another with a "through" crack, the remaining specimens contain surface-breaking cracks. All of the specimens were inspected for the cracks intersecting the back wall, and some were flipped over and re-inspected with the crack intersecting the front surface. Parameter and variable sensitivity studies were performed using CIVA Simulation Software. In contrast to C-scans where detection and localization of small cracks can be very difficult, modeling and initial experimental results demonstrate that cracks can be accurately located in "True" B-scans (B-scans projected in the part along the beam path). Initial results show that small-amplitude diffracted/scattered signals from the crack tips and edges are essential in obtaining clear crack traces in the True B-scans. It is important therefore that experimental data be acquired with sufficient gain to capture the diffracted/scattered signals. In all of the cases studied here, saturating the high-amplitude specular reflections from the fastener hole and crack enhanced the crack trace in the True B-scans. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
132. Model-based Inverse Methods for Sizing Cracks ofVarying Shape and Location in Bolt-hole Eddy Current (BHEC) Inspections.
- Author
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Aldrin, John C., Sabbagh, Harold A., Zhao, Liming, Sabbagh, Elias, Murphy, R. Kim, Keiser, Mark, Flores-Lamb, Jennifer, Forsyth, David S., Motes, Doyle, Lindgren, Eric A., and Mooers, Ryan
- Subjects
- *
EDDY currents (Electric) , *INVERSION (Geophysics) , *FRACTURE mechanics , *INSPECTION & review , *THICKNESS measurement , *SIGNAL processing - Abstract
A comprehensive approach is presented to perform model-based inversion of crack characteristics using bolt hole eddy current (BHEC) techniques. Data was acquired for a wide range of crack sizes and shapes, including mid-bore, corner and through-thickness crack types, and from both standard eddy current hardware and a prototype BHEC system with z-axis position encoding. Signal processing algorithms were developed to process and extract features from the 2D data sets, and inversion algorithms using VIC-3D generated surrogate models were used for inverting crack size. New model results are presented, which now address the effect of having a corner crack at an edge and a through crack adjacent to two edges. A two-step inversion process was implemented that first evaluates the material layer thickness, crack type and location, in order to select the most appropriate VIC-3D surrogate model for subsequent crack sizing inversion step. Inversion results for select mid-bore, through and corner crack specimens are presented where sizing performance was found to be satisfactory in general, but also depend on the size and location of the flaw. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
133. Eddy-Current NDE Inverse Problem with Sparse Grid Algorithm.
- Author
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Zhou, Liming, Sabbagh, Harold A., Sabbagh, Elias H., Murphy, R. Kim, Bernacchi, William, Aldrin, John C., Forsyth, David, and Lindgren, Eric
- Subjects
- *
EDDY currents (Electric) , *NONDESTRUCTIVE testing , *INVERSE problems , *ALGORITHMS , *PARAMETER estimation - Abstract
In model-based inverse problems, the unknown parameters (such as length, width, depth) need to be estimated. When the unknown parameters are few, the conventional mathematical methods are suitable. But the increasing number of unknown parameters will make the computation become heavy. To reduce the burden of computation, the sparse grid algorithm was used in our work. As a result, we obtain a powerful interpolation method that requires significantly fewer support nodes than conventional interpolation on a full grid. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
134. Nondestructive Damage Characterization of Complex Aircraft Structures by Inverse Methods: Advances in Multiscale Models.
- Author
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Murphy, R. Kim, Sabbagh, Harold A., Sabbagh, Elias H., Zhou, Liming, Bernacchi, William, Aldrin, John C., Forsyth, David, and Lindgren, Eric
- Subjects
- *
NONDESTRUCTIVE testing , *AIRFRAMES , *MULTISCALE modeling , *EDDY current testing , *ELECTRIC coils - Abstract
The use of coupled integral equations and anomalous currents allows us to efficiently remove 'background effects' in either forward or inverse modeling. This is especially true when computing the change in impedance due to a small flaw in the presence of a larger background anomaly. It is more accurate than simply computing the response with and without the flaw and then subtracting the two nearly equal values to obtain the small difference due to the flaw. The problem that we address in this paper involves a 'SplitD' probe that includes complex, noncircular coils, as well as ferrite cores, inserted within a bolt hole, and exciting both the bolt hole and an adjacent flaw. This introduces three coupled anomalies, each with its on 'scale.' The largest, of course, is the bolt hole, followed (generally) by the probe, and then the flaw. The overall system is represented mathematically by three coupled volume-integral equations. We describe the development of the model and its code, which is a part of the general eddy-current modeling code, VIC-3DR®. We present initial validation results, as well as a number of model computations with flaws located at various places within the bolt hole. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
135. Damage Localization Using Ultrasonic Methods in Multi-Layered Metallic Structures.
- Author
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Hopkins, Deborah, Datuin, Marvin, Aldrin, John, Forsyth, David, Warchol, Mark, and Warchol, Lyudmila
- Subjects
- *
ALUMINUM plates , *ULTRASONIC waves , *SURFACE cracks , *FASTENERS , *LAYER structure (Solids) , *REFLECTIONS - Abstract
Results are presented from a highly collaborative project that builds on previous research designed to improve ultrasonic (UT) localization of damage in mutli-layer metallic structures. One of the primary objectives of the project is to test existing acoustic models for cracks around fastener holes, and further develop a model as necessary to achieve the accuracy required for Air Force applications. For the first phase of the project, CIVA modeling results have been compared to ultrasonic measurements on aluminum plates with fatigue cracks and EDM notches at different locations around throughthickness holes. Variables include the diameter of the holes, length/width of notches/cracks, position of notches/cracks on the hole (angle with respect to the probe) and position in depth (surface, mid bore, backwall and through thickness). Baseline measurements have also been made on side-drilled and spherical-tip holes. Modeling challenges include accurately accounting for reflections arising from the cracks and the specimen geometry, mode conversion, contact conditions between fasteners and fastener holes, and reflection/transmission coefficients at interfaces between layers. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
136. Evaluating environmental, demographic and genetic effects on population-level survival in an island endemic.
- Author
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Purwandana, Deni, Ariefiandy, Achmad, Imansyah, M. Jeri, Ciofi, Claudio, Forsyth, David M., Gormley, Andrew M., Rudiharto, Heru, Seno, Aganto, Fordham, Damien A., Gillespie, Graeme, and Jessop, Tim S.
- Subjects
- *
ENDEMIC animals , *ANIMAL genetics , *LIZARD populations , *HABITATS , *KOMODO dragon , *ANIMAL species - Abstract
The population dynamics of island species are considered particularly sensitive to variation in environmental, demographic and/or genetic processes. However, few studies have attempted to evaluate the relative importance of these processes for key vital rates in island endemics. We integrated the results of long-term capture-mark-recapture analysis, prey surveys, habitat quality assessments and molecular analysis to determine the causes of variation in the survival rates of Komodo dragons Varanus komodoensis at 10 sites on four islands in Komodo National Park, Indonesia. Using open population capture-mark-recapture methods, we ranked competing models that considered environmental, ecological, genetic and demographic effects on site-specific Komodo dragon survival rates. Site-specific survival rates ranged from 0.49 (95% CI: 0.33-0.68) to 0.92 (0.79-0.97) in the 10 study sites. The three highest-ranked models (i.e. ΔQAIC c < 2) explained ∼70% of variation in Komodo dragon survival rates and identified interactions between inbreeding coefficients, prey biomass density and habitat quality as important explanatory variables. There was evidence of additive effects from ecological and genetic (e.g. inbreeding) processes affecting Komodo dragon survival rates. Our results indicate that maintaining high ungulate prey biomass and habitat quality would enhance the persistence of Komodo dragon populations. Assisted gene flow may also increase the genetic and demographic viability of the smaller Komodo dragon populations. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
137. Performance enhancement of pre-spectrum slicing technique for wavelength conversion.
- Author
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Kharraz, Osayd M., Ahmad, Harith, Mohammad, Abu Bakar B., Forsyth, David I., Dernaika, Mohamad, and Harun, Sulaiman W.
- Subjects
- *
WAVELENGTHS , *ENERGY conversion , *SIGNAL-to-noise ratio , *BRAGG gratings , *COST effectiveness - Abstract
This paper details a proposal and successful demonstration of an ultra-narrow and very high optical signal-to-noise ratio wavelength converted channel that was generated from an efficient ultra-narrow pre-spectrum sliced probe channel via four-wave mixing in a highly non-linear fiber medium. An array of narrowband fiber Bragg grating filters acted as a discriminative component to pre-spectrum slice the probe channel from backward amplified spontaneous emission, which, in turn, induced an additional fiber Bragg grating filtering mechanism within an erbium-doped fiber medium in a saturable configuration. A resultant optical signal-to-noise ratio of more than 70 dB in the probe channel gave rise to a 40 dB optical signal-to-noise ratio in the converted channel. These outcomes indicate the proposed scheme is highly suitable for practical, cost-effective wavelength conversion in any “pre-spectrum sliced” optical communication system. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
138. Model-based Inverse Methods for Bolt-holt Eddy Current (BHEC) Inspections.
- Author
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Aldrin, John C., Sabbagh, Harold A., Sabbagh, Elias, Murphy, R. Kim, Keiser, Mark, Forsyth, David S., and Lindgren, Eric A.
- Subjects
- *
EDDY current testing , *NONDESTRUCTIVE testing , *DATA analysis , *FRACTURE mechanics , *MATHEMATICAL models - Abstract
This work presents a comprehensive approach for model-based inversion of crack characteristics using eddy current nondestructive evaluation (NDE) and includes a demonstration using a bolt-hole eddy-current (BHEC) technique. Data were acquired using standard eddy current hardware for crack and notch samples of varying size and profile. The inversion results were found to be accurate within 10% for sizing the depth of through cracks and able to accurately bin mid-bore cracks by size. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
139. Causes and consequences of ground disturbance by feral pigs (Sus scrofa) in a lowland New Zealand conifer-angiosperm forest.
- Author
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Parkes, John P., Easdale, Tomás A., Williamson, Wendy M., and Forsyth, David M.
- Subjects
- *
WILD boar , *ECOLOGICAL impact , *FERAL pigeons , *SEEDLINGS - Abstract
The ecological impacts of feral pigs (Sus scrofa) are of concern in many places around the world. One noticeable impact is soil disturbance, although the causes and consequences are often unclear. We measured the effect of ground disturbance by feral pigs on seedling recruitment and soil ecology over 25 months on a forested riparian terrace at Waitutu, south Fiordland, New Zealand, and assessed the diet of pigs from the area from stomach contents of animals shot by hunters. Foraging by feral pigs for below-ground food disturbed between 7.4% and 12.4% of the soil. Pigs were seven times more likely to redisturb a site than to disturb a new site. Below-ground food items constituted a third of pigs' diet and were dominated by stag beetle larvae. Sites disturbed by feral pigs had shorter seedlings compared with undisturbed sites, but this was due to pigs' choice of sites rather than a consequence of the disturbance. Net temporal changes in density and height of seedlings were similarly slow in both disturbed and undisturbed sites. The basal respiration of microbes in soils recently disturbed by pigs was significantly higher than that for undisturbed soils. There was a suggestion that disturbed soils had higher ratios of fungi to bacteria than undisturbed soils (P = 0.06). This may reflect either disturbance favouring fungi over bacteria or selection of sites with more fungi or more of their main prey, the fungivorous stag beetle Dorcus helmsii. Our results indicate that pigs disturb soil primarily to forage for food and that the consequences of disturbance for seedling regeneration and soil ecology are limited or neutral. The consequences of ground disturbance and predation for populations of animal prey, such as the stag beetles, require further investigation. [ABSTRACT FROM AUTHOR]
- Published
- 2015
140. GMR sensing array technique validation study for the inspection of multi-layer metallic structures.
- Author
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Motes, Doyle, Aldrin, John C., Keiser, Mark, Steffes, Gary, and Forsyth, David S.
- Subjects
- *
MAGNETORESISTANCE , *ENGINEERING inspection , *FATIGUE crack growth , *STRUCTURAL engineering , *METALS testing , *DETECTORS , *MICROFABRICATION - Abstract
Giant Magnetoresistive (GMR) sensing arrays have been developed to detect fatigue cracks in thick, multi-layered metallic structures. As part of a program conducted by the U.S. Air Force Research Laboratory, fatigue crack specimens were fabricated to provide inspection targets for a GMR array. These specimens were mounted to simulate a wing structure and inspected using a Boeing Mobile Automated Scanner (MAUS). Probability of Detection (POD) from inspections and the results of capability studies are presented. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
141. Modeling of Semiconductor Optical Amplifier Gain Characteristics for Amplification and Switching.
- Author
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Mahad, Farah Diana, Sahmah, Abu, Supa'at, M., Idrus, Sevia Mahdaliza, and Forsyth, David
- Subjects
- *
MATHEMATICAL models , *SEMICONDUCTORS , *OPTICAL amplifiers , *SWITCHING circuits , *COMMUNICATION , *COMPUTER software , *SIMULATION methods & models - Abstract
The Semiconductor Optical Amplifier (SOA) is presently commonly used as a booster or pre-amplifier in some communication networks. However, SOAs are also a strong candidate for utilization as multi-functional elements in future all-optical switching, regeneration and also wavelength conversion schemes. With this in mind, the purpose of this paper is to simulate the performance of the SOA for improved amplification and switching functions. The SOA is modeled and simulated using OptSim software. In order to verify the simulated results, a MATLAB mathematical model is also used to aid the design of the SOA. Using the model, the gain difference between simulated and mathematical results in the unsaturated region is <1dB. The mathematical analysis is in good agreement with the simulation result, with only a small offset due to inherent software limitations in matching the gain dynamics of the SOA. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
142. Reliable Discrimination of 10 Ungulate Species Using High Resolution Melting Analysis of Faecal DNA.
- Author
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Ramón-Laca, Ana, Gleeson, Dianne, Yockney, Ivor, Perry, Michael, Nugent, Graham, and Forsyth, David M.
- Subjects
- *
MELTING points , *MAMMALS , *ARTIODACTYLA , *ECOSYSTEMS , *HIMALAYAN tahr , *COMPUTATIONAL biology - Abstract
Identifying species occupying an area is essential for many ecological and conservation studies. Faecal DNA is a potentially powerful method for identifying cryptic mammalian species. In New Zealand, 10 species of ungulate (Order: Artiodactyla) have established wild populations and are managed as pests because of their impacts on native ecosystems. However, identifying the ungulate species present within a management area based on pellet morphology is unreliable. We present a method that enables reliable identification of 10 ungulate species (red deer, sika deer, rusa deer, fallow deer, sambar deer, white-tailed deer, Himalayan tahr, Alpine chamois, feral sheep, and feral goat) from swabs of faecal pellets. A high resolution melting (HRM) assay, targeting a fragment of the 12S rRNA gene, was developed. Species-specific primers were designed and combined in a multiplex PCR resulting in fragments of different length and therefore different melting behaviour for each species. The method was developed using tissue from each of the 10 species, and was validated in blind trials. Our protocol enabled species to be determined for 94% of faecal pellet swabs collected during routine monitoring by the New Zealand Department of Conservation. Our HRM method enables high-throughput and cost-effective species identification from low DNA template samples, and could readily be adapted to discriminate other mammalian species from faecal DNA. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
143. Animal welfare science aids conservation.
- Author
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Hampton, Jordan O., Baker, Sandra E., Beausoleil, Ngaio J., Cattet, Marc, Forsyth, David M., McMahon, Clive R., Proulx, Gilbert, and Warburton, Bruce
- Subjects
- *
ANIMAL welfare , *SCIENCE , *STRUGGLE - Abstract
The article presents N. Sekar and D. Shiller overlooking a history of conservation-related animal welfare science and the integration of animal welfare science and conservation spans, and understanding and incorporating animal welfare science to benefit conservation efforts.
- Published
- 2020
- Full Text
- View/download PDF
144. Novel Picornavirus Detected in Wild Deer: Identification, Genomic Characterisation, and Prevalence in Australia.
- Author
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Huaman, Jose L., Pacioni, Carlo, Sarker, Subir, Doyle, Mark, Forsyth, David M., Pople, Anthony, Carvalho, Teresa G., and Helbig, Karla J.
- Subjects
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FALLOW deer , *RED deer , *WHOLE genome sequencing , *GENOMICS , *DOMESTIC animals , *DEER - Abstract
The use of high-throughput sequencing has facilitated virus discovery in wild animals and helped determine their potential threat to humans and other animals. We report the complete genome sequence of a novel picornavirus identified by next-generation sequencing in faeces from Australian fallow deer. Genomic analysis revealed that this virus possesses a typical picornavirus-like genomic organisation of 7554 nt with a single open reading frame (ORF) encoding a polyprotein of 2225 amino acids. Based on the amino acid identity comparison and phylogenetic analysis of the P1, 2C, 3CD, and VP1 regions, this novel picornavirus was closely related to but distinct from known bopiviruses detected to date. This finding suggests that deer/bopivirus could belong to a novel species within the genus Bopivirus, tentatively designated as "Bopivirus C". Epidemiological investigation of 91 deer (71 fallow, 14 sambar and 6 red deer) and 23 cattle faecal samples showed that six fallow deer and one red deer (overall prevalence 7.7%, 95% confidence interval [CI] 3.8–15.0%) tested positive, but deer/bopivirus was undetectable in sambar deer and cattle. In addition, phylogenetic and sequence analyses indicate that the same genotype is circulating in south-eastern Australia. To our knowledge, this study reports for the first time a deer-origin bopivirus and the presence of a member of genus Bopivirus in Australia. Further epidemiological and molecular studies are needed to investigate the geographic distribution and pathogenic potential of this novel Bopivirus species in other domestic and wild animal species. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
145. Comparative performance testing of SOA wavelength conversion techniques for future all-optical systems
- Author
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Mahad, Farah Diana, Supa’at, Abu Sahmah M., Idrus, Sevia Mahdaliza, and Forsyth, David
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SEMICONDUCTOR optical amplifiers , *WAVELENGTHS , *PERFORMANCE evaluation , *COMPARATIVE studies , *ELECTRONIC modulation , *SPECTRUM analysis - Abstract
Abstract: Wavelength conversion employing semiconductor optical amplifiers (SOAs) is currently one of the most attractive and promising wavelength conversion techniques for future all-optical systems. This paper investigates the comparative performances of the three most popular SOA wavelength conversion techniques; cross-gain modulation (XGM), cross-phase modulation (XPM) and four-wave mixing (FWM). The FWM wavelength converter is analyzed for two types of source; a CW and a novel spectrum-sliced source. All performances are analyzed in terms of shifted wavelength conversion efficiency, Q-factors and converted signal powers. The converters are modeled and simulated using OptSim software. It was found that XGM yields the highest conversion efficiency of 17dB, followed by XPM having 9dB. The FWM wavelength converter had the lowest conversion efficiency, around −0.7dB and −5.0dB for CW and spectrum-sliced sources respectively. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
146. Monitoring the ungulate prey of the Komodo dragon Varanus komodoensis: distance sampling or faecal counts?
- Author
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Ariefiandy, Achmad, Purwandana, Deni, Coulson, Graeme, Forsyth, David M., and Jessop, Tim S.
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PREDATION , *PREDATORY animals , *ENDANGERED species , *CERVUS timorensis , *KOMODO dragon - Abstract
Monitoring the abundances of prey is important for informing the management of threatened and endangered predators. We evaluated the usefulness of faecal counts and distance sampling for monitoring the abundances of rusa deer Rusa timorensis, feral pig Sus scrofa and water buffalo Bubalus bubalis, the three key prey of the Komodo dragon Varanus komodoensis, at 11 sites on five islands in and aroundKomodoNational Park, eastern Indonesia.We used species-specific global detection functions and cluster sizes (i.e. multiple covariates distance sampling) to estimate densities of rusa deer and feral pig, but there were too few observations to estimate densities of water buffalo. Rusa deer densities varied from from 2.5 to 165.5 deer/km2 with coefficients of variation (CVs) of 15-105%. Feral pig densities varied from 0.0 to 25.2 pigs/km2 with CVs of 25-106%. There was a positive relationship between estimated faecal densities and estimated population densities for both rusa deer and feral pig: the form of the relationship was non-linear for rusa deer, but there was similar support for linear and non-linear relationships for feral pig. We found that faecal counts were more useful when ungulate densities were too low to estimate densities with distance sampling. Faecal count methods were also easier for field staff to conduct than distance sampling. Because spatial and temporal variation in ungulate density is likely to influence the population dynamics of the Komodo dragon, we recommend that annual monitoring of ungulates in and around Komodo National Park be undertaken using distance sampling and faecal counts. The relationships reported here will also be useful for managers establishing monitoring programmes for feral pig, rusa deer and water buffalo elsewhere in their native and exotic ranges. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
147. Life-History and Spatial Determinants of Somatic Growth Dynamics in Komodo Dragon Populations.
- Author
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Laver, Rebecca J., Purwandana, Deni, Ariefiandy, Achmad, Imansyah, Jeri, Forsyth, David, Ciofi, Claudio, Jessop, Tim S., and Walker, Sean
- Subjects
- *
KOMODO dragon , *ANIMAL population density , *INBREEDING , *REPRODUCTION ,GROWTH research - Abstract
Somatic growth patterns represent a major component of organismal fitness and may vary among sexes and populations due to genetic and environmental processes leading to profound differences in life-history and demography. This study considered the ontogenic, sex-specific and spatial dynamics of somatic growth patterns in ten populations of the world's largest lizard the Komodo dragon (Varanus komodoensis). The growth of 400 individual Komodo dragons was measured in a capture-mark-recapture study at ten sites on four islands in eastern Indonesia, from 2002 to 2010. Generalized Additive Mixed Models (GAMMs) and information-theoretic methods were used to examine how growth rates varied with size, age and sex, and across and within islands in relation to site-specific prey availability, lizard population density and inbreeding coefficients. Growth trajectories differed significantly with size and between sexes, indicating different energy allocation tactics and overall costs associated with reproduction. This leads to disparities in maximum body sizes and longevity. Spatial variation in growth was strongly supported by a curvilinear density-dependent growth model with highest growth rates occurring at intermediate population densities. Sex-specific trade-offs in growth underpin key differences in Komodo dragon life-history including evidence for high costs of reproduction in females. Further, inverse density-dependent growth may have profound effects on individual and population level processes that influence the demography of this species. [ABSTRACT FROM AUTHOR]
- Published
- 2012
- Full Text
- View/download PDF
148. Simulation on semiconductor optical amplifier intensity noise reduction for future spectrum-sliced optical networks
- Author
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Mahad, Farah Diana, Supa’at, Abu Sahmah M., Idrus, Sevia Mahdaliza, and Forsyth, David
- Subjects
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OPTICAL amplifiers , *WAVELENGTH division multiplexing , *LOCAL area networks , *SIMULATION methods & models , *OPTICAL properties of semiconductors , *ELECTRIC noise - Abstract
Abstract: Spectrum-slicing techniques employing incoherent light are an economic, practical and therefore attractive solution for future all-optical networks, especially for wavelength-division multiplexing (WDM) transmission systems in local area networks (LAN). However, spectrum-sliced methods exhibit a large excess intensity noise factor that limits the performance of the system. In this paper, we investigate noise suppression of spectrum-sliced incoherent light using a saturated semiconductor optical amplifier (SOA). The system incorporating the noise reducing SOA is modeled and simulated using OptSim software, and the results are compared to practical schemes from the literature. Performance comparisons are made with two different broadband sources test-beds. The characteristics of the SOA gain saturation are also presented. In both cases, it is found that a high degree of intensity noise is suppressed by the use of the non-linear gain saturation characteristics of the SOA so as to achieve better system performance. The position of a modulator in the system is also investigated in order to greatly reduce the excess intensity noise. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
149. Do leaves of plants on phosphorus-impoverished soils contain high concentrations of phenolic defence compounds?
- Author
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Wright, David M., Jordan, Greg J., Lee, William G., Duncan, Richard P., Forsyth, David M., and Coomes, David A.
- Subjects
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PLANT-soil relationships , *PHOSPHORUS , *LEAVES , *PLANT ecology , *PHENOLS - Abstract
1. Prominent theories of plant defence have predicted that plants growing on nutrient-poor soils produce more phenolic defence compounds than those on richer soils. Only recently has the Protein Competition Model (PCM) of phenolic allocation suggested that N and P limitation could have different effects because the nutrients are involved in different cellular metabolic processes. 2. We extend the prediction of the PCM and hypothesize that N will have a greater influence on the production of phenolic defensive compounds than P availability, because N limitation reduces protein production and thus competition for phenylalanine, a precursor of many phenolic compounds. In contrast, P acts as a recyclable cofactor in these reactions, allowing protein and hence phenolic production to continue under low P conditions. 3. We test this hypothesis by comparing the foliar concentrations of phenolic compounds in (i) phenotypes of 21 species growing on P-rich alluvial terraces and P-depleted marine terraces in southern New Zealand, and (ii) 87 species growing under similar climates on comparatively P-rich soils in New Zealand vs. P-depleted soils in Tasmania. 4. Foliar P concentrations of plants from the marine terraces were about half those of plants from alluvial soils, and much lower in Tasmania than in New Zealand. However, foliar concentrations of N and phenolic compounds were similar across sites in both comparisons, supporting the hypothesis that N availability is a more important determinant of plant investment in phenolic defensive compounds than P availability. We found no indication that reduced soil P levels influenced plant concentrations of phenolic compounds. There was wide variation in the foliar N and P concentrations among species, and those with low foliar nutrient concentrations produced more phenolics (including condensed tannins). 5. Our study is the first trait comparison extending beyond standard leaf economics to include secondary metabolites related to defence in forest plants, and emphasizes that N and P have different influences on the production of phenolic defence compounds. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
150. Molecular Epidemiology and Characterization of Picobirnavirus in Wild Deer and Cattle from Australia: Evidence of Genogroup I and II in the Upper Respiratory Tract.
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Huaman, Jose L., Pacioni, Carlo, Sarker, Subir, Doyle, Mark, Forsyth, David M., Pople, Anthony, Hampton, Jordan O., Carvalho, Teresa G., and Helbig, Karla J.
- Subjects
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MOLECULAR epidemiology , *RNA replicase , *DEER , *GENETIC variation , *CATTLE , *RESPIRATORY infections - Abstract
Picobirnaviruses (PBVs) have been detected in several species of animals worldwide; however, data pertaining to their presence in Australian wild and domestic animals are limited. Although PBVs are mostly found in faecal samples, their detection in blood and respiratory tract samples raises questions concerning their tropism and pathogenicity. We report here PBV detection in wild deer and cattle from southeastern Australia. Through metagenomics, the presence of PBV genogroups I (GI) and II (GII) were detected in deer serum and plasma. Molecular epidemiology studies targeting the partial RNA-dependent RNA polymerase gene were performed in a wide range of specimens (serum, faeces, spleen, lung, nasal swabs, and trachea) collected from wild deer and cattle, with PCR amplification obtained in all specimen types except lung and spleen. Our results reveal the predominance of GI and concomitant detection of both genogroups in wild deer and cattle. In concordance with other studies, the detected GI sequences displayed high genetic diversity, however in contrast, GII sequences clustered into three distinct clades. Detection of both genogroups in the upper respiratory tract (trachea and nasal swab) of deer in the present study gives more evidence about the respiratory tract tropism of PBV. Although much remains unknown about the epidemiology and tropism of PBVs, our study suggests a wide distribution of these viruses in southeastern Australia. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
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