5 results on '"Webb, M.A."'
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2. Digital mapping of a soil drainage index for irrigated enterprise suitability in Tasmania, Australia
- Author
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Kidd, D.B., Malone, B.P., McBratney, A.B., Minasny, B., and Webb, M.A.
- Subjects
Soil research ,Soil permeability -- Research ,Digital mapping -- Methods ,Drainage -- Research ,Agricultural industry ,Earth sciences - Abstract
An operational Digital Soil Assessment was developed to inform land suitability modelling in newly commissioned irrigation schemes in Tasmania, Australia. The Land Suitability model uses various soil parameters, along with other climate and terrain surfaces, to identify suitable areas for various agricultural enterprises for a combined 70000-ha pilot project area in the Meander and Midlands Regions of Tasmania. An integral consideration for irrigable suitability is soil drainage. Quantitative measurement and mapping can be resource-intensive in time and associated costs, whereas more 'traditional' mapping approaches can be generalised, lacking the detail required for statistically validated products. The project was not sufficiently resourced to undertake replicated field-drainage measurements and relied on expert field drainage estimates at ~930 sites (260 of these for independent validation) to spatially predict soil drainage for both areas using various terrain-based and remotely sensed covariates, using three approaches: (a) decision tree spatial modelling of discrete drainage classes; (b) regression-tree spatial modelling of a continuous drainage index; (c) regression kriging (random-forests with residual-kriging) spatial modelling of a continuous drainage index. Method b was chosen as the best approach in terms of interpretation, and model training and validation, with a concordance coefficient of 0.86 and 0.57, respectively. A classified soil drainage map produced from the 'index' showed good agreement, with a linearly weighted kappa coefficient of 0.72 for training, and 0.37 for validation. The index mapping was incorporated into the overall land suitability model and proved an important consideration for the suitability of most enterprises. Additional keywords: decision trees, digital soil mapping, land suitability, regression trees, random forests, soil drainage, spatial modelling. Received 25 March 2013, accepted 24 September 2013, published online 6 March 2014, Introduction Tasmania has a population of ~500000 people, with a cool temperate climate, and rainfall ranging from >500 mm [year.sup.-1] in the central Midlands to < 1800 mm [year.sup.-1] on [...]
- Published
- 2014
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3. Follicles, germinal centers, and immune mechanisms in primary biliary cirrhosis
- Author
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M.R.C.P. Gwilym J. Webb M.A. and F.R.C.P. Gideon M. Hirschfield Ph.D.
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Male ,Hepatology ,business.industry ,Liver Cirrhosis, Biliary ,Germinal center ,T-Lymphocytes, Helper-Inducer ,medicine.disease ,Article ,Primary biliary cirrhosis ,Immunology ,Medicine ,Humans ,Female ,business ,Immune mechanisms - Abstract
There is increasing interest in the role of T follicular helper (Tfh) cells in autoimmunity from the perspective of both their role in breach of tolerance and their effects on the natural history of disease progression. Indeed, the critical role of Tfh cells in autoimmunity is further highlighted based on their location in the germinal center (GC), a pathogenic hot spot for development of autoreactivity. To address the role of Tfh cells in primary biliary cirrhosis (PBC), we comprehensively evaluated the immunobiology of CXCR5+CD4+ Tfh cells in 69 patients with PBC, including a nested subgroup of 16 autoimmune hepatitis (AIH) and 20 healthy controls (HC), followed for one year. We report herein several key observations. Firstly, there was an increased frequency of circulating Tfh cells in patients with PBC compared to AIH (p < 0.05) and HC (p < 0.01). Second, the function of circulating Tfh cells from PBC patients, including IL-21 production (p < 0.05), the ability to promote B cell maturation and autoantibody production, were greater than HC. Third, the frequency of these cells was significantly decreased in UDCA responders compared to UDCA-treated non-responders, in both cross-sectional (p = 0.023) and longitudinal studies (p = 0.036),respectively. Indeed, similar increases of Tfh cells were noted in liver and spleen. In conclusion, these results significantly extend our understanding of lymphoid subpopulations in PBC and their relative role in disease expression. Our data also provide a novel biomarker for evaluation of the effectiveness of new therapeutic approaches.
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- 2014
4. Shake the disease
- Author
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Murray, Rob and Webb, M.A.
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General interest ,News, opinion and commentary - Abstract
Another fine article by Anne Kingston on multiple sclerosis (' 'Canada's disease,' ' Society, April 27). At the turn of the century, MS was called faker's disease. Eventually, radiology showed [...]
- Published
- 2015
5. Synchrotron x-ray fluorescence (SXRF) analysis of palaeofluid chemistry from the McArthur River uranium deposit, Athabasca Basin, Canada: results and implications.
- Author
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McCready A.J., Uranium production and raw materials for the nuclear fuel cycle: supply and demand, economics, the environment and energy security: Extended synopses, Vienna 20-Jun-0524-Jun-05 IAEA; OECD Nuclear Energy Agency; The World Nuclear Association; The Nuclear Energy Institute; UNECE, Annesley I.R., Bakker R.J., Cavell R.G., Cuney M., Derome D., Rickers K., Webb M.A., McCready A.J., Uranium production and raw materials for the nuclear fuel cycle: supply and demand, economics, the environment and energy security: Extended synopses, Vienna 20-Jun-0524-Jun-05 IAEA; OECD Nuclear Energy Agency; The World Nuclear Association; The Nuclear Energy Institute; UNECE, Annesley I.R., Bakker R.J., Cavell R.G., Cuney M., Derome D., Rickers K., and Webb M.A.
- Abstract
The 20 to 50 micron fluid inclusions investigated were either from inclusion-rich quartz or occurred as isolated inclusions in quartz. Solid phases included halite, phyllosilicates and haematite. All the inclusions contained Fe, Br and Sr along with a number of other elements, including U. Elements that are known to be present from microthermometry were either not detected (including Na and Cl) or only detected occasionally (K, Ca); SXRF is probably more suited to analysing elements with a heavier mass than these. The presence of U in the inclusions indicates that fluids trapped within the quartz were able to transport significant amounts of metals, including U and LREE. The presence of Ce could indicate that uranium was sourced from monazite. Uranium also occurred in inclusion-free quartzes, which could suggest that the ore-fluid was saturated with respect to uranium., The 20 to 50 micron fluid inclusions investigated were either from inclusion-rich quartz or occurred as isolated inclusions in quartz. Solid phases included halite, phyllosilicates and haematite. All the inclusions contained Fe, Br and Sr along with a number of other elements, including U. Elements that are known to be present from microthermometry were either not detected (including Na and Cl) or only detected occasionally (K, Ca); SXRF is probably more suited to analysing elements with a heavier mass than these. The presence of U in the inclusions indicates that fluids trapped within the quartz were able to transport significant amounts of metals, including U and LREE. The presence of Ce could indicate that uranium was sourced from monazite. Uranium also occurred in inclusion-free quartzes, which could suggest that the ore-fluid was saturated with respect to uranium.
- Published
- 2006
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