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Search Results: 1 - 10 of 11280 matches for " George Shedrawi "
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Digitise This! A Quick and Easy Remote Sensing Method to Monitor the Daily Extent of Dredge Plumes
Richard D. Evans, Kathy L. Murray, Stuart N. Field, James A. Y. Moore, George Shedrawi, Barton G. Huntley, Peter Fearns, Mark Broomhall, Lachlan I. W. McKinna, Daniel Marrable
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0051668
Abstract: Technological advancements in remote sensing and GIS have improved natural resource managers’ abilities to monitor large-scale disturbances. In a time where many processes are heading towards automation, this study has regressed to simple techniques to bridge a gap found in the advancement of technology. The near-daily monitoring of dredge plume extent is common practice using Moderate Resolution Imaging Spectroradiometer (MODIS) imagery and associated algorithms to predict the total suspended solids (TSS) concentration in the surface waters originating from floods and dredge plumes. Unfortunately, these methods cannot determine the difference between dredge plume and benthic features in shallow, clear water. This case study at Barrow Island, Western Australia, uses hand digitising to demonstrate the ability of human interpretation to determine this difference with a level of confidence and compares the method to contemporary TSS methods. Hand digitising was quick, cheap and required very little training of staff to complete. Results of ANOSIM R statistics show remote sensing derived TSS provided similar spatial results if they were thresholded to at least 3 mg L?1. However, remote sensing derived TSS consistently provided false-positive readings of shallow benthic features as Plume with a threshold up to TSS of 6 mg L?1, and began providing false-negatives (excluding actual plume) at a threshold as low as 4 mg L?1. Semi-automated processes that estimate plume concentration and distinguish between plumes and shallow benthic features without the arbitrary nature of human interpretation would be preferred as a plume monitoring method. However, at this stage, the hand digitising method is very useful and is more accurate at determining plume boundaries over shallow benthic features and is accessible to all levels of management with basic training.
Sediment and Turbidity Associated with Offshore Dredging Increase Coral Disease Prevalence on Nearby Reefs
F. Joseph Pollock, Joleah B. Lamb, Stuart N. Field, Scott F. Heron, Britta Schaffelke, George Shedrawi, David G. Bourne, Bette L. Willis
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0102498
Abstract: In recent decades, coral reef ecosystems have declined to the extent that reefs are now threatened globally. While many water quality parameters have been proposed to contribute to reef declines, little evidence exists conclusively linking specific water quality parameters with increased disease prevalence in situ. Here we report evidence from in situ coral health surveys confirming that chronic exposure to dredging-associated sediment plumes significantly increase the prevalence of white syndromes, a devastating group of globally important coral diseases. Coral health surveys were conducted along a dredging-associated sediment plume gradient to assess the relationship between sedimentation, turbidity and coral health. Reefs exposed to the highest number of days under the sediment plume (296 to 347 days) had two-fold higher levels of disease, largely driven by a 2.5-fold increase in white syndromes, and a six-fold increase in other signs of compromised coral health relative to reefs with little or no plume exposure (0 to 9 days). Multivariate modeling and ordination incorporating sediment exposure level, coral community composition and cover, predation and multiple thermal stress indices provided further confirmation that sediment plume exposure level was the main driver of elevated disease and other compromised coral health indicators. This study provides the first evidence linking dredging-associated sedimentation and turbidity with elevated coral disease prevalence in situ. Our results may help to explain observed increases in global coral disease prevalence in recent decades and suggest that minimizing sedimentation and turbidity associated with coastal development will provide an important management tool for controlling coral disease epizootics.
Unprecedented Mass Bleaching and Loss of Coral across 12° of Latitude in Western Australia in 2010–11
James A. Y. Moore, Lynda M. Bellchambers, Martial R. Depczynski, Richard D. Evans, Scott N. Evans, Stuart N. Field, Kim J. Friedman, James P. Gilmour, Thomas H. Holmes, Rachael Middlebrook, Ben T. Radford, Tyrone Ridgway, George Shedrawi, Heather Taylor, Damian P. Thomson, Shaun K. Wilson
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0051807
Abstract: Background Globally, coral bleaching has been responsible for a significant decline in both coral cover and diversity over the past two decades. During the summer of 2010–11, anomalous large-scale ocean warming induced unprecedented levels of coral bleaching accompanied by substantial storminess across more than 12° of latitude and 1200 kilometers of coastline in Western Australia (WA). Methodology/Principal Findings Extreme La-Ni?a conditions caused extensive warming of waters and drove considerable storminess and cyclonic activity across WA from October 2010 to May 2011. Satellite-derived sea surface temperature measurements recorded anomalies of up to 5°C above long-term averages. Benthic surveys quantified the extent of bleaching at 10 locations across four regions from tropical to temperate waters. Bleaching was recorded in all locations across regions and ranged between 17% (±5.5) in the temperate Perth region, to 95% (±3.5) in the Exmouth Gulf of the tropical Ningaloo region. Coincident with high levels of bleaching, three cyclones passed in close proximity to study locations around the time of peak temperatures. Follow-up surveys revealed spatial heterogeneity in coral cover change with four of ten locations recording significant loss of coral cover. Relative decreases ranged between 22%–83.9% of total coral cover, with the greatest losses in the Exmouth Gulf. Conclusions/Significance The anomalous thermal stress of 2010–11 induced mass bleaching of corals along central and southern WA coral reefs. Significant coral bleaching was observed at multiple locations across the tropical-temperate divide spanning more than 1200 km of coastline. Resultant spatially patchy loss of coral cover under widespread and high levels of bleaching and cyclonic activity, suggests a degree of resilience for WA coral communities. However, the spatial extent of bleaching casts some doubt over hypotheses suggesting that future impacts to coral reefs under forecast warming regimes may in part be mitigated by southern thermal refugia.
Dynamic Stability of Coral Reefs on the West Australian Coast
Conrad W. Speed, Russ C. Babcock, Kevin P. Bancroft, Lynnath E. Beckley, Lynda M. Bellchambers, Martial Depczynski, Stuart N. Field, Kim J. Friedman, James P. Gilmour, Jean-Paul A. Hobbs, Halina T. Kobryn, James A. Y. Moore, Christopher D. Nutt, George Shedrawi, Damian P. Thomson, Shaun K. Wilson
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0069863
Abstract: Monitoring changes in coral cover and composition through space and time can provide insights to reef health and assist the focus of management and conservation efforts. We used a meta-analytical approach to assess coral cover data across latitudes 10–35°S along the west Australian coast, including 25 years of data from the Ningaloo region. Current estimates of coral cover ranged between 3 and 44% in coral habitats. Coral communities in the northern regions were dominated by corals from the families Acroporidae and Poritidae, which became less common at higher latitudes. At Ningaloo Reef coral cover has remained relatively stable through time (~28%), although north-eastern and southern areas have experienced significant declines in overall cover. These declines are likely related to periodic disturbances such as cyclones and thermal anomalies, which were particularly noticeable around 1998/1999 and 2010/2011. Linear mixed effects models (LME) suggest latitude explains 10% of the deviance in coral cover through time at Ningaloo. Acroporidae has decreased in abundance relative to other common families at Ningaloo in the south, which might be related to persistence of more thermally and mechanically tolerant families. We identify regions where quantitative time-series data on coral cover and composition are lacking, particularly in north-western Australia. Standardising routine monitoring methods used by management and research agencies at these, and other locations, would allow a more robust assessment of coral condition and a better basis for conservation of coral reefs.
Venture Capital and Innovation in Europe  [PDF]
George Geronikolaou, George Papachristou
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.34058
Abstract: In this paper we search for evidence signifying whether VC activity is demand or supply stimulated. Namely, we examine whether innovation and entrepreneurship are fostered by Venture Capital (VC) investments or whether innovative entrepreneurship is a precondition of a VC involvement. Based on a European panel of VC investments, we test the direction of causality between VC and innovation (proxied by annual patent applications at the European Patents Office). We present evidence indicating that causality runs from patents to VC suggesting that, in Europe, innovation seems to create a demand for VC and not VC a supply of innovation. In this sense, innovative ideas seem to lack more than funds in Europe. We explain our findings on the basis of information asymmetry issues and irreversibility considerations of VC investments.
The Index of Invariant Subspaces of Bounded below Operators on Banach Spaces  [PDF]
George Chailos
Advances in Pure Mathematics (APM) , 2012, DOI: 10.4236/apm.2012.22018
Abstract: For an operator on a Banach space , let be the collection of all its invariant subspaces. We consider the index function on and we show, amongst others, that if is a bounded below operator and if , , then If in addition are index 1 invariant subspaces of , with nonzero intersection, we show that . Furthermore, using the index function, we provide an example where for some , holds .
General Markowitz Optimization Problems  [PDF]
George Stoica
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312A281
Abstract:

We solve two Markowitz optimization problems for the one-step financial model with a finite number of assets. In our results, the classical (inefficient) constraints are replaced by coherent measures of risk that are continuous from below. The methodology of proof requires optimization techniques based on functional analysis methods. We solve explicitly both problems in the important case of Tail Value at Risk.

A Spectral Integral Equation Solution of the Gross-Pitaevskii Equation  [PDF]
George Rawitscher
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410A3009
Abstract:

The Gross-Pitaevskii equation (GPE), that describes the wave function of a number of coherent Bose particles contained in a trap, contains the cube of the normalized wave function, times a factor proportional to the number of coherent atoms. The square of the wave function, times the above mentioned factor, is defined as the Hartree potential. A method implemented here for the numerical solution of the GPE consists in obtaining the Hartree potential iteratively, starting with the Thomas Fermi approximation to this potential. The energy eigenvalues and the corresponding wave functions for each successive potential are obtained by a spectral method described previously. After approximately 35 iterations a stability of eight significant figures for the energy eigenvalues is obtained. This method has the advantage of being physically intuitive, and could be extended to the calculation of a shell-model potential in nuclear physics, once the Pauli exclusion principle is allowed for.

Rethinking the Formal Methodology (II): Cognitive Content of Relativity (On the Centenary of General Relativity)  [PDF]
George Kirakosyan
International Journal of Astronomy and Astrophysics (IJAA) , 2016, DOI: 10.4236/ijaa.2016.61004
Abstract: An attempt to epistemological completion of formal-math theories of relativity is presented. Causal interpretations of SR and GR are suggested. The problem to physical gist of gravity is explained as a contradiction of cognition vs. intuition. Gravity phenomena are represented as unexplored peculiarity of basic particles. The gravity constant is deduced from the known parameters of the electron.
Small Scale Contractors in Africa’s Emerging Markets: The Case of South Africa  [PDF]
George Hove
Open Journal of Business and Management (OJBM) , 2016, DOI: 10.4236/ojbm.2016.44065
Abstract: In South Africa, the development of Small scale emerging contractors (SSECs) has become vital to bring about economic prosperity and the government has prioritised the advancement of SSECs as the vehicle towards achieving economic growth, development and job creation for previously disadvantaged people. This paper reviewed related construction studies on small scale contractors and highlighted unique roles and challenges as they relate to emerging construction businesses. The paper established that the main challenges affecting SSECs included finance, skills shortage, enabling environment and competition. Based on data analysis, it is imperative for the South African government to develop a clear and more comprehensive small business contracting policies that would enhance growth and profitability of Small scale emerging contractors.
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