576 research outputs found

    Geochemical zoning and early differentiation in the moon

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    The volatile elements (e.g., Rb, Pb, Tl, Bi, Cs) seem to have been depleted at the time of lunar accretion. Accordingly, it may be assumed that the moon initially accreted from refractory material. The good correlation between volatile/involatile element ratios (e.g., Cs/U, K/La, K/Zr) in both highland and maria samples means that element distribution in lunar crustal rocks is not governed by volatility differences. This and other evidence encourages the view that the moon was accreted homogeneously. A consequence of homogeneous accretion theories is that very efficient large-scale element fractionation is required to account both for the high near-surface concentrations of refractory elements (e.g., Th, U, REE, Zr, Ba, etc.) and for the Ca-Al-rich crust

    Experimental evidence for the relaxation coupling of all longitudinal 7Li magnetization orders in the superionic conductor Li10GeP2S12

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    This contribution addresses the experimental proof of the relaxation coupling of the 7Li (I = 3/2) longitudinal magnetization orders in the solid-state electrolyte Li10GeP2S12 (LGPS). This effect was theoretically described by Korb and Petit in 1988 but has not yet been shown experimentally. In a 2D-T1/spin-alignment echo (SAE) experiment, the inverse Laplace transformation of the spectral component over two time dimensions revealed the asymmetric course of the spin-lattice relaxation following from the coupling of all longitudinal orders. These observations were supported by Multi-quantum-filter experiments and by simulations of the 2D-T1/SAE experiment with a lithium spin system. Since the asymmetric relaxation effects are directly dependent on the velocities and degrees of freedom of ion motion they could be used especially in fast Li-ion conductors as a separation tool for environments with different mobility processes

    Social science to improve fuels management: A synthesis of research on collaboration

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    This document is part of the Fuels Planning: Science Synthesis and Integration Project, a pilot project initiated by the USDA Forest Service to respond to the need for tools and information useful for planning site-specific fuel (vegetation) treatment projects. The information addresses fuel and forest conditions of the dry inland forests of the Western United States: those dominated by ponderosa pine, Douglas-fir, dry grand fir/white fir, and dry lodgepole pine potential vegetation types. Information was developed primarily for application at the stand level and is intended to be useful within this forest type regardless of ownership. Portions of the information also will be directly applicable to the pinyon pine/juniper potential vegetation types. Many of the concepts and tools developed by the project may be useful for planning fuel projects in other forest types. In particular, many of the social science findings would have direct applicability to fuel planning activities for forests throughout the United States

    Humans, Fires, and Forests: Social science applied to fire management: workshop summary, Tucson, Arizona, January 28-31, 2003.

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    This summary of the January 26-28, 2003 workshop held in Tucson, Arizona, presents the record of the meeting. It includes the full text of the invited theme papers, the managerial and policy talks, annotated outlines of the breakout sessions and the closing, wrap-up presentation. It also includes a reflective after-the-workshop summary and synthesis paper. This record, however, is only one product of the meeting. In addition to the networking that occurred, researchers attending the workshop also committed to several on-going activities designed both to foster communications among scholars as well as to maximize the utility of social science research applied to fire management. Examples of such activities include: preparation of a social science expertise directory, development of a research framework to demonstrate how various work nodes are relating to one another and where there are still significant gaps, and planning for sessions at the July 2003 Natural Hazards workshop in Boulder, Colorado, and the 2004 ISSRM conference in Keystone, Colorado

    Cotunneling through a magnetic single-molecule transistor based on N\atC60

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    We present an experimental and theoretical study of a magnetic single-molecule transistor based on N@C60 connected to gold electrodes. Particular attention is paid to the regime of intermediate molecule-lead coupling, where cotunneling effects manifest themselves in the Coulomb-blockade regime. The experimental results for the differential conductance as a function of bias, gate voltage, and external magnetic field are in agreement with our analysis of the tunneling rates and provide evidence of magnetic signatures in single-N@C60 devices arising from an antiferromagnetic exchange interaction between the C60 spin and the nitrogen spin.Comment: Accepted for publication in PRB Rapid Com, 4 pages, 4 figures, with supplementary information (6 pages, 3 figures

    Theory for transport through a single magnetic molecule: Endohedral N@C60

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    We consider transport through a single N@C60 molecule, weakly coupled to metallic leads. Employing a density-matrix formalism we derive rate equations for the occupation probabilities of many-particle states of the molecule. We calculate the current-voltage characteristics and the differential conductance for N@C60 in a break junction. Our results reveal Coulomb-blockade behavior as well as a fine structure of the Coulomb-blockade peaks due to the exchange coupling of the C60 spin to the spin of the encapsulated nitrogen atom.Comment: 5 pages, 4 figures, v2: version as publishe

    Haemoprotozoan parasites of tortoises in southeast Queensland

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