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Search Results: 1 - 10 of 309677 matches for " Andrew J. Heyward "
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Habitat Specialization in Tropical Continental Shelf Demersal Fish Assemblages
Ben M. Fitzpatrick, Euan S. Harvey, Andrew J. Heyward, Emily J. Twiggs, Jamie Colquhoun
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0039634
Abstract: The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types. The assemblage composition of demersal fish were assessed from baited remote underwater stereo-video samples (n = 304) collected from 16 depth and habitat combinations. Samples were collected across a depth range poorly represented in the literature from the fringing reef lagoon (1–10 m depth), down the fore reef slope to the reef base (10–30 m depth) then across the adjacent continental shelf (30–110 m depth). Multivariate analyses showed that there were distinctive fish assemblages and different sized fish were associated with each habitat/depth category. Species richness, MaxN and diversity declined with depth, while average length and trophic level increased. The assemblage structure, diversity, size and trophic structure of demersal fishes changes from shallow inshore habitats to deeper water habitats. More habitat specialists (unique species per habitat/depth category) were associated with the reef slope and reef base than other habitats, but offshore sponge-dominated habitats and inshore coral-dominated reef also supported unique species. This suggests that marine protected areas in shallow coral-dominated reef habitats may not adequately protect those species whose depth distribution extends beyond shallow habitats, or other significant elements of demersal fish biodiversity. The ontogenetic habitat partitioning which is characteristic of many species, suggests that to maintain entire species life histories it is necessary to protect corridors of connected habitats through which fish can migrate.
Novel Genetic Diversity Through Somatic Mutations: Fuel for Adaptation of Reef Corals?
Madeleine J. H. Van Oppen,Petra Souter,Emily J. Howells,Andrew Heyward,Ray Berkelmans
Diversity , 2011, DOI: 10.3390/d3030405
Abstract: Adaptation of reef corals to climate change is an issue of much debate, and often viewed as too slow a process to be of relevance over decadal time scales. This notion is based on the long sexual generation times typical for some coral species. However, the importance of somatic mutations during asexual reproduction and growth on evolution and adaptation ( i.e., cell lineage selection) is rarely considered. Here we review the existing literature on cell lineage selection and show that the scope for somatic mutations to arise in the coral animal and associated Symbiodinium is large. For example, we estimate that ~100 million somatic mutations can arise within a branching Acropora coral colony of average size. Similarly, the large population sizes and rapid turn-over times of in hospite Symbiodinium likely result in considerable numbers of somatic mutations. While the fate of new mutations depends on many factors, including ploidy level and force and direction of selection, we argue that they likely play a key role in the evolution of reef corals.
Using Age-Based Life History Data to Investigate the Life Cycle and Vulnerability of Octopus cyanea
Jade N. Herwig, Martial Depczynski, John D. Roberts, Jayson M. Semmens, Monica Gagliano, Andrew J. Heyward
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0043679
Abstract: Octopus cyanea is taken as an unregulated, recreationally fished species from the intertidal reefs of Ningaloo, Western Australia. Yet despite its exploitation and importance in many artisanal fisheries throughout the world, little is known about its life history, ecology and vulnerability. We used stylet increment analysis to age a wild O. cyanea population for the first time and gonad histology to examine their reproductive characteristics. O. cyanea conforms to many cephalopod life history generalisations having rapid, non-asymptotic growth, a short life-span and high levels of mortality. Males were found to mature at much younger ages and sizes than females with reproductive activity concentrated in the spring and summer months. The female dominated sex-ratios in association with female brooding behaviours also suggest that larger conspicuous females may be more prone to capture and suggests that this intertidal octopus population has the potential to be negatively impacted in an unregulated fishery. Size at age and maturity comparisons between our temperate bordering population and lower latitude Tanzanian and Hawaiian populations indicated stark differences in growth rates that correlate with water temperatures. The variability in life history traits between global populations suggests that management of O. cyanea populations should be tailored to each unique set of life history characteristics and that stylet increment analysis may provide the integrity needed to accurately assess this.
Hydrothermally synthesized α-Ba2P2O7
Carla Heyward,Matthew Mann,Joseph Kolis
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810043527
Abstract: Single crystals of α-Ba2P2O7, dibarium diphosphate, were obtained under hydrothermal conditions. The structure belongs to the diphosphate A2P2O7 series with A being an alkaline earth cation. α-Ba2P2O7 crystallizes isotypically with α-Sr2P2O7. All atomic sites have site symmetry m with the exception of two O atoms which reside on general positions. Both Ba2+ cations are coordinated by nine terminal O atoms from eclipsed diphosphate P2O7 anions to form a three-dimensional network throughout the structure.
The Global Crisis’ Impact upon China’s Rural Migrants
Sara Hsu,Shiyin Jiang,Halcott Heyward
Journal of Current Chinese Affairs , 2010,
Abstract: Towards the end of 2008, as the world economy slowed and export-demand declined due to the global financial crisis, news reports began to appear detailing the return of rural migrants in China to their provincial homes. It was reported that 20 million rural migrant workers were laid off, and social instability rose due to both economic hardship and to the withholding of the payment of wages. Over time, these circumstances have changed, due to both the Chinese government’s fiscal stimulus package and to those programmes that have been targeted specifically at assisting the country’s rural migrants. As a result, the situation for rural migrants is no longer dire; circumstances have been greatly ameliorated by proactive government policies. To confirm these results, in this paper we look both at the situation across China and briefly at a study carried out in Sichuan province.
Spatial and temporal variability of soil freeze-thaw cycling across Southern Alberta, Canada  [PDF]
Andrew J. Phillips, Nathaniel K. Newlands
Agricultural Sciences (AS) , 2011, DOI: 10.4236/as.2011.24051
Abstract: Soil freeze-thaw cycles play an important role in all aspects of agro-ecosystems, such as crop productivity, the evolution of the soil matrix, including trace-gas emissions. In regions that experience synoptic weather conditions throughout the winter, freeze-thaw cycles generally occur in one of two categories; seasonal or winter cycles. Current soil vegetation atmosphere models (SVAT’s) often include a heat-transport soil freeze-thaw algorithm, but lack detail on complex interactions between the main driving variables. Boundary conditions for these models are often based only on a few climate variables and typically lack regional context. A nested statistical analysis was applied to identify the optimal set of environmental variables (via a stepwise regression selection procedure) to track soil freeze-thaw dynamics. Historical data collected between the years 2006-2009, for 17 long-term climate stations distributed across southern Alberta Canada was utilized. Cross-correlation between wind speed and maximum air temperature identified Chinook-driven freeze-thaw events, with such interaction varying significantly across the region and by soil depth. Climate-soil interactions were most significant predictors of soil temperature during winter months. The seasonal freeze-thaw cycle is estimated to vary between 112 - 131 days, consisting of 12 - 20 winter cycles (1 cm depth), and 1-5 winter cycles (5 cm depth) with average lag time of 26 - 112 days. Freeze-thaw prediction was greatly improved when higher-order climate interaction terms were considered. Our findings highlight the importance for soil-water and more complex ecosystem, SVAT models to better resolve regional-driven climatic trends. Alongside improved representation of regional trends aimed at reducing model-based uncertainty, such efforts are expected to, in tandem, help advance the geostatistical design, and implementation of agroenvironmental monitoring systems that combine in-situ and satellite/remote-sensing derived estimates of near-surface soil moisture.
Emotions and Emotion Regulation in a Female Couple Undergoing in Vitro Fertilization Treatment  [PDF]
Tracey J. Devonport, Andrew M. Lane
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.46A1004
Abstract:

Research indicates that women undergoing In Vitro Fertilization (IVF) experience intense unwanted emotions, and that these emotions may result in the decision to abandon treatment. This case-study explored stressors, emotional responses and emotion regulation strategies of a female couple undergoing IVF procedures over a ten-week period. A mixed-method approach involved participants completing a daily open-ended diary and self-report scales to assess emotions and emotion regulation in relation to partner and self. Diary results indicated both partners experienced frequent stressors resulting from the IVF process, stressors that were intensified by perceptual and financial factors. Participants experienced a range of intense pleasant (e.g., happy, excited) and unpleasant emotions (e.g., depressed, anxious), and sought to down-regulate unpleasant emotions using a range of cognitive, behavioral, and social strategies. Questionnaire data indicated complementary styles of emotion regulation that appeared to help sustain pleasant emotions and down-regulate unpleasant emotions. Future research should test the effectiveness of interventions to help manage unwanted emotional responses to IVF treatment and corresponding regulatory efforts.

A Novel Approach for Sugarcane Yield Prediction Using Landsat Time Series Imagery: A Case Study on Bundaberg Region  [PDF]
Muhammad Moshiur Rahman, Andrew J. Robson
Advances in Remote Sensing (ARS) , 2016, DOI: 10.4236/ars.2016.52008
Abstract: Quantifying sugarcane production is critical for a wide range of applications, including crop management and decision making processes such as harvesting, storage, and forward selling. This study explored a novel model for predicting sugarcane yield in Bundaberg region from time series Landsat data. From the freely available Landsat archive, 98 cloud free (<40%) Landsat Thematic Mapper (TM) and Enhanced Thematic Mapper (ETM+) images, acquired between November 15th to July 31st (2001-2015) were sourced for this study. The images were masked using the field boundary layer vector files of each year and the GNDVI was calculated. An analysis of average green normalized difference vegetation index (GNDVI) values from all sugarcane crops grown within the Bundaberg region over the 15 year period identified the beginning of April as the peak growth stage and, therefore, the optimum time for satellite image based yield forecasting. As the GNDVI is an indicator of crop vigor, the model derived maximum GNDVI was regressed against historical sugarcane yield data, which showed a significant correlation with R2 = 0.69 and RMSE = 4.2 t/ha. Results showed that the model derived maximum GNDVI from Landsat imagery would be a feasible and a modest technique to predict sugarcane yield in Bundaberg region.
Estimating a Falsified Model  [PDF]
Andrew J. Buck, George M. Lady
Advances in Pure Mathematics (APM) , 2016, DOI: 10.4236/apm.2016.68040
Abstract: It is common econometric practice to propose a system of equations, termed the “structure,” estimate each endogenous variable in the structure via a linear regression with all of the exogenous variables as arguments, and then employ one of variety of regression techniques to recapture the coefficients in the (Jacobian) arrays of the structure. A recent literature, e.g., [1], has shown that a qualitative analysis of a model’s structural and estimated reduced form arrays can provide a robust procedure for assessing if a model’s hypothesized structure has been falsified. This paper shows that the even weaker statement of the model’s structure provided by zero restrictions on the structural arrays can be falsified, independent of the proposed nonzero entries. When this takes place, multi-stage least squares, or any procedure for estimating the structural arrays with the zero restrictions imposed, will present estimates that could not possibly have generated the data upon which the estimated reduced form is based. The examples given in the paper are based upon a Monte Carlo sampling procedure.
Epidural Blood Patch for Treatment of Postdural Puncture Headache in a Patient with Spinal Fusion and Recent Implantation of Intrathecal Pain Pump  [PDF]
Chistopher J. Burnett,Andrew J. White,Marius D. Vulcan
Open Journal of Anesthesiology (OJAnes) , 2013, DOI: 10.4236/ojanes.2013.33039
Abstract: We present an interesting case report of a 49-year-old female who presented with symptoms of post-dural puncture headache following implantation of an intrathecal pain pump. Her history was complicated by previous multi-level spinal fusion with hardware. The patient was evaluated and felt to be a candidate for epidural blood patch, which she elected to proceed with. Under fluoroscopic guidance epidural blood patch was successfully performed. Immediately following the procedure the patient noted significant improvement in the headache and six hours following the procedure was headache free and remained so at follow up three weeks later.
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