76 research outputs found

    The Palaeozoic metamorphic evolution of the Alpine External Massifs

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    The pre-Mesozoic metamorphic pattern of the External Massifs, composed of subunits of different metamorphic histories, resulted from the telescoping of Variscan, Ordovician and older metamorphic and structural textures and formations. During an early period, the future External Massifs were part of a peri-Gondwanian microplate evolving as an active margin. Precambrian to lower Palaeozoic igneous and sedimentary protoliths were reworked during an Ordovician subduction cycle (eclogites, granulites) preceding Ordovician anatexis and intrusion of Ordovician granitoids. Little is known about the time period when the microcontinent containing the future External Massifs followed a migration path leading to collision with Laurussia. Corresponding rock-series have not been identified. This might be because they have been eroded or transformed by migmatisation or because they remain hidden in the monocyclic areas. Besides the transformations which originated during the Ordovician subduction cycle, strong metamorphic transformations resulted from Variscan collision when many areas underwent amphibolite facies transformations and migmatisation. The different subunits composing the External Massifs and their corresponding P-T evolution are the expression of different levels in a nappe pile, which may have formed before Visean erosion and cooling. The presence of durbachitic magmatic rocks may be the expression of a large scale Early Variscan upwelling line which formed after Variscan lithospheric subduction. Late Variscan wrench fault tectonics and crustal thinning accompanied by high thermal gradients triggered several pulses of granite intrusions

    Theoretical characterization of a model of aragonite crystal orientation in red abalone nacre

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    Nacre, commonly known as mother-of-pearl, is a remarkable biomineral that in red abalone consists of layers of 400-nm thick aragonite crystalline tablets confined by organic matrix sheets, with the (001)(001) crystal axes of the aragonite tablets oriented to within ±\pm 12 degrees from the normal to the layer planes. Recent experiments demonstrate that this orientational order develops over a distance of tens of layers from the prismatic boundary at which nacre formation begins. Our previous simulations of a model in which the order develops because of differential tablet growth rates (oriented tablets growing faster than misoriented ones) yield patterns of tablets that agree qualitatively and quantitatively with the experimental measurements. This paper presents an analytical treatment of this model, focusing on how the dynamical development and eventual degree of order depend on model parameters. Dynamical equations for the probability distributions governing tablet orientations are introduced whose form can be determined from symmetry considerations and for which substantial analytic progress can be made. Numerical simulations are performed to relate the parameters used in the analytic theory to those in the microscopic growth model. The analytic theory demonstrates that the dynamical mechanism is able to achieve a much higher degree of order than naive estimates would indicate.Comment: 20 pages, 3 figure

    Stripe-Like Inhomogeneities, Spectroscopies, Pairing, and Coherence in the High-Tc Cuprates

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    It is found that the carriers of the high-T_c cuprates are polaron-like "stripons" carrying charge and located in stripe-like inhomogeneities, "quasi-electrons" carrying charge and spin, and "svivons" carrying spin and lattice distortion. This is shown to result in the observed anomalous spectroscopic properties of the cuprates. The AF/stripe-like inhomogeneities result from the Bose condensation of the svivon field, and the speed of their dynamics is determined by the width of the double-svivon neutron-resonance peak. Pairing results from transitions between pair states of stripons and quasi-electrons through the exchange of svivons. The obtained pairing symmetry is of the d_{x^2-y^2} type; however, sign reversal through the charged stripes results in features not characteristic of this symmetry. The phase diagram is determined by a pairing and a coherence line, associated with a Mott transition, and the pseudogap state corresponds to incoherent pairing.Comment: 13 pages, 8 figures; version including recent references, to be published in J. Phys. Chem. Solid

    Systematic tight-binding analysis of ARPES spectra of transition-metal oxides

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    We have performed systematic tight-binding (TB) analyses of the angle-resolved photoemission spectroscopy (ARPES) spectra of transition-metal (TM) oxides AMMO3_3 (M=M= Ti, V, Mn, and Fe) with the perovskite-type structure and compared the obtained parameters with those obtained from configuration-interaction (CI) cluster-model analyses of photoemission spectra. The values of ϵdϵp\epsilon_d-\epsilon_p from ARPES are found to be similar to the charge-transfer energy Δ\Delta from O 2p2p orbitals to empty TM 3d orbitals and much larger than ΔU/2\Delta-U/2 (UU: on-site Coulomb energy) expected for Mott-Hubbard-type compounds including SrVO3_3. ϵdϵp\epsilon_d-\epsilon_p values from {\it ab initio} band-structure calculations show similar behaviors to those from ARPES. The values of the pdp-d transfer integrals to describe the global electronic structure are found to be similar in all the estimates, whereas additional narrowing beyond the TB description occurs in the ARPES spectra of the dd band.Comment: 5 pages, 3 figure

    Crop Updates 2010 - Farming Systems

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    This session covers twenty papers from different authors: Pests and Disease 1. Preserving phosphine for use in Grain Storage Industry, Christopher R Newman, Department of Agriculture and Food Farming Systems Research 2. Demonstrating the benefits of grazing canola in Western Australia, Jonathan England, Stephen Gherardi and Mohammad Amjad, Department of Agriculture and Food 3. Buloke barley yield when pasture-cropped across subtropical perennial pastures, David Ferris, Department of Agriculture and Food, Phil Ward and Roger Lawes, CSIRO 4. Is pasture cropping viable in WA? Grower perceptions and EverCrop initiatives to evaluate, David Ferris, Tim Wiley, Perry Dolling, Department of Agriculture and Food, Philip Barrett-Lennard, Evergreen farming 5. Best-bet management for dual-purpose canola, John Kirkegaard, Susan Sprague, Hugh Dove and Walter Kelman, CSIRO, Canberra, Peter Hamblin, Agritech Research, Young, NSW 6. Pasture in cropping systems – with and without sheep, Brad Nutt and Angelo Loi, Department of Agriculture and Food 7. Can technology substitute for a lupin break? Wayne Parker, Department of Agriculture and Food 8. Canola row spacing with and without long term stubble retention on a sandy clay loam at Merredin, Glen Riethmuller, Department of Agriculture and Food 9. Impact of stubble retention on water balance and crop yield, Phil Ward1, Ken Flower2,3, Neil Cordingley2 and Shayne Micin1, 1CSIRO, Wembley, Western Australia, 2Western Australian No-Till Farmers Association, 3University of Western Australia Analysis and Modelling 10. Using POAMA rainfall forecasts for crop management in South-West WA, Senthold Asseng1, Peter McIntosh2,3, Mike Pook2,3, James Risbey2,3, Guomin Wang3, Oscar Alves3, Ian Foster4, Imma Farre4 and Nirav Khimashia1, 1CSIRO Plant Industry, Perth, 2CSIRO Marine and Atmospheric Research, Hobart, 3Centre for Australian Weather and Climate Research (CAWCR), A partnership between the Australian Bureau of Meteorology and CSIRO, Melbourne, 4Department of Agriculture and Food 11. Adaption to changing climates and variability – results of the Agribusiness Changing Climates regional workshop, Anderson W3, Beard D3, Blake J3, Grieve R1, Lang M3, Lemon J3, McTaggart R3, Gray D3, Price M2 and Stephens D3, 1Roderick Grieve Farm Management Consultants, 2Coffey International P/L, 3Department of Agriculture and Food 12. Farmers’ management of seasonal variability and climate change in WA, DA Beard, DM Gray, P Carmody, Department of Agriculture and Food 13. Is there a value in having a frost forecast for wheat in South-West WA? Imma Farre1, Senthold Asseng2, Ian Foster1 and Doug Abrecht3, 1Department of Agriculture and Food, CSIRO, Floreat, 2CSIRO Plant Industry, Perth 3Department of Agriculture and Food, Centre for Cropping Systems 14. Does buying rainfall pay? Greg Kirk, Planfarm Agricultural Consultants 15. Which region in the WA wheatbelt makes best use of rainfall? Peter Rowe, Bankwest Agribusiness 16. POAMA – the Predictive Ocean-Atmosphere Model for Australia, Guomin Wang and Oscar Alves, Centre for Australian Weather and Climate Research (CAWCR), A partnership between the Australian Bureau of Meteorology and CSIRO, Melbourne 17. Exploring the link between water use efficiency and farm profitability, Cameron Weeks, Planfarm and Peter Tozer, PRT Consulting Precision Agriculture 18. A plethora of paddock information is available – how does it stack up? Derk Bakker, Department of Agriculture and Food 18. Variable rate prescription mapping for lime inputs based on electromagnetic surveying and deep soil testing, Frank D’Emden, Quenten Knight and Luke Marquis, Precision Agronomics, Australia 19. Trial design and analysis using precision agriculture and farmer’s equipment, Roger Lawes, CSIRO Sustainable Ecosystems, Centre for Environment and Life Sciences, Floreat 20. Farmer perspectives of precision agriculture in Western Australia: Issues and the way forward, Dr Roger Mandel, Curtin Universit

    Concentration Dependent Ion Selectivity in VDAC: A Molecular Dynamics Simulation Study

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    The voltage-dependent anion channel (VDAC) forms the major pore in the outer mitochondrial membrane. Its high conducting open state features a moderate anion selectivity. There is some evidence indicating that the electrophysiological properties of VDAC vary with the salt concentration. Using a theoretical approach the molecular basis for this concentration dependence was investigated. Molecular dynamics simulations and continuum electrostatic calculations performed on the mouse VDAC1 isoform clearly demonstrate that the distribution of fixed charges in the channel creates an electric field, which determines the anion preference of VDAC at low salt concentration. Increasing the salt concentration in the bulk results in a higher concentration of ions in the VDAC wide pore. This event induces a large electrostatic screening of the charged residues promoting a less anion selective channel. Residues that are responsible for the electrostatic pattern of the channel were identified using the molecular dynamics trajectories. Some of these residues are found to be conserved suggesting that ion permeation between different VDAC species occurs through a common mechanism. This inference is buttressed by electrophysiological experiments performed on bean VDAC32 protein akin to mouse VDAC

    Crop updates 2006 - Farming Systems

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    This session covers nineteen papers from different authors: SOIL AND NUTRIENT MANAGEMENT 1. Invetigatingfertilitigating fertilier inve$tment, Wayne Pluske, Nutrient Management Systems 2. KASM, the potassium in Agricultural System Model,Bill Bowden and Craig Scanlan, DAWA Northam and UWA, School of Earth and Geographical Sciences 3. Long term productivity and economic benefits of subsurface acidity management from surface and subsurface liming, Stephen Davies, Chris Gazey and Peter Tozer, Department of Agriculture 4. Furrow and ridges to prevent waterlogging, Dr Derk Bakker, Department of Agriculture 5. Nitrous oxide emissions from a cropped soil in Western Australia, Louise Barton1, David Gatter2, Renee Buck1, Daniel Murphy1, Christoph Hinz1and Bill Porter2 1School of Earth and Geographical Sciences, The University of Western Australia, 2Department of Agriculture GROWER DECISIONS 6. Managing the unmanageable, Bill Bowden Department of Agriculture 7. Review of climate model summaries reported in Department of Agriculture’s Season Outlook, Meredith Fairbanks, Department of Agriculture 8. Mapping the frost risk in Western Australia, Nicolyn Short and Ian Foster, Department of Agriculture 9. .35 kg/ha.day and other myths, James Fisher, Doug Abrecht and Mario D’Antuono, Department of Agriculture 10. Gaining with growers – Lessons from a successful alliance of WA Grower Groups, Tracey M. Gianatti, Grower Group Alliance 11. WA Agribusiness Trial Network Roundup – 2005, Paul Carmody, Local Farmer Group Network, UWA 12. Drivers of no-till adoption, Frank D’Emdenabc, Rick Llewellynabdand Michael Burtonb,aCRC Australian Weed Management; bSchool of Agricultural and Resource Economics, UWA. cDepartment of Agriculture, dCSIRO Sustainable Ecosystems, Adelaide PRODUCTION SYSTEMS, PRECISION AGRICULTURE AND SUSTAINABILITY 13. Maintaining wheat and lupin yields using phase pastures and shielded sprayers to manage increasing herbicide resistance, Caroline Peek, Nadine Eva, Chris Carter and Megan Abrahams, Department of Agriculture 14. Analaysis of a wheat-pasture rotation in the 330mm annual rainfall zone using the STEP model, Andrew Blake and Caroline Peek, Department of Agriculture 15. Response to winter drought by wheat on shallow soil with low seeding rate and wide row spacing, Paul Blackwell1, Sylvain Pottier2and Bill Bowden1 1 Department of Agriculture; 2Esitpa (France) 16. How much yield variation do you need to justify zoning inputs? Michael Robertson and Greg Lyle, CSIRO Floreat, Bill Bowden, Department of Agriculture; Lisa Brennan, CSIRO Brisbane 17. Automatic guidance and wheat row position: On-row versus between-row seeding at various rates of banded P fertilisers, Tony J. Vyn1, Simon Teakle2, Peter Norris3and Paul Blackwell4,1Purdue University, USA; 2Landmark; 3Agronomy for Profit; 4 Department of Agriculture 18. Assessing the sustainability of high production systems (Avon Agricultural Systems Project), Jeff Russell and James Fisher, Department of Agriculture, Roy Murray-Prior and Deb Pritchard, Muresk Institute; Mike Collins, ex WANTFA, 19. The application of precision agriculture techniques to assess the effectiveness of raised beds on saline land in WA, Derk Bakker, Greg Hamilton, Rob Hetherington, Andrew Van Burgel and Cliff Spann, Department of Agricultur
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