5,568 research outputs found

    Temperature dependence of the phonon entropy of vanadium

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    The phonon density-of-states (DOS) of elemental vanadium was measured at elevated temperatures by inelastic neutron scattering. The phonon softening predicted by thermal expansion against the bulk modulus is much larger than the measured shifts in phonon energies. We conclude that the phonon anharmonicities associated with thermal expansion are largely canceled by effects from phonon-phonon scattering. Prior measurements of the heat capacity and calculations of the electronic entropy of vanadium are assessed, and consistency requires an explicit temperature dependence of the phonon DOS. Using data from the literature, similar results are found for chromium, niobium, titanium, and zirconium

    An Evaluation of Organizational and Experience Factors Affecting the Perceived Transfer of U.S. Air Force Basic Combat Skills Training

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    The United States Air Force is in a state of transformation. Due to ongoing operations in Iraq and Afghanistan, the focus of Basic Military Training is shifting to basic combat skills, or the skills needed to survive and operate in a hostile environment. In this study, basic combat skills training was evaluated using a number of training factors that potentially affect trainees’ perception of training transfer, or their ability to apply the skills they learned in training on the job or in a hostile environment. The analysis used structural equation modeling to evaluate the paths between each of the factors and perceived training transfer. Of the factors analyzed, transfer enhancing activities and perceived utility were found to positively influence perceived training transfer for all training types, while organizational support for training was positive for Law of Armed Conflict training only. Deployment experience was positive for weapons training, but negative for Self-Aid and Buddy Care. Realistic job preview was positively related to training transfer, but was only significant with respect to Self-Aid and Buddy Care training. The results of this research may help enhance basic combat skills training and do so at little or no cost

    Equal Consideration and Systematic Measurement Error in Hydroelectric Relicensing

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    Glyphosate Resistant Palmer amaranth (\u3ci\u3eAmaranthus palmeri\u3c/i\u3e) management late-season and POST-harvest in corn production systems

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    The objectives of this research were to evaluate control options for glyphosate resistant (GR) Palmer amaranth (Amaranthus palmeri) latelate-season in corn systems and POST-harvest for the prevention of seed production. Our results determined that the best late-season control methods were treatments tank-mixed with dicamba plus diflufenzopyr. These tank-mixtures improved control from 10 to 46% [percent] over treatments without the dicamba premix. Tankmixtures with dicamba plus diflufenzopyr that provided weed control \u3e [greater than] 96% 28 DAA included s-metolachlor plus glyphosate plus mesotrione and tembotrione plus thiencarbazone. For the prevention of POST-harvest GR palmer amaranth seed production, our results determined that paraquat provides excellent initial control of existing vegetation but regrowth can occur from larger plants. The addition of a residual herbicide may aid in controlling regrowth as well as preventing plant germination. All treatments provided enough control for the prevention of seed production. Through implementation of POST-harvest management practices, 1200 seed per m2 [meter squared] was prevented from replenishing the soil seed bank. There were no adverse affects on wheat yield. From these results, we can conclude that when practicing POST only weed management strategies, application timing is vital for the prevention of corn loss and that implementation of late-season weed management programs can effectively reduce weed seed rain, therefore reducing weed seed bank densities

    Renormalized parameters and perturbation theory for an n-channel Anderson model with Hund's rule coupling: Asymmetric case

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    We explore the predictions of the renormalized perturbation theory for an n-channel Anderson model, both with and without Hund's rule coupling, in the regime away from particle-hole symmetry. For the model with n=2 we deduce the renormalized parameters from numerical renormalization group calculations, and plot them as a function of the occupation at the impurity site, nd. From these we deduce the spin, orbital and charge susceptibilities, Wilson ratios and quasiparticle density of states at T=0, in the different parameter regimes, which gives a comprehensive overview of the low energy behavior of the model. We compare the difference in Kondo behaviors at the points where nd=1 and nd=2. One unexpected feature of the results is the suppression of the charge susceptibility in the strong correlation regime over the occupation number range 1 <nd <3.Comment: 9 pages, 17 figure

    Special studies of AROD system concepts and designs

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    Signal processing techniques for range and range rate measurements in airborne range and orbit determinatio

    Fermi Liquids and the Luttinger Integral

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    The Luttinger Theorem, which relates the electron density to the volume of the Fermi surface in an itinerant electron system, is taken to be one of the essential features of a Fermi liquid. The microscopic derivation of this result depends on the vanishing of a certain integral, the Luttinger integral ILI_{\rm L}, which is also the basis of the Friedel sum rule for impurity models, relating the impurity occupation number to the scattering phase shift of the conduction electrons. It is known that non-zero values of ILI_{\rm L} with IL=±π/2I_{\rm L}=\pm\pi/2, occur in impurity models in phases with non-analytic low energy scattering, classified as singular Fermi liquids. Here we show the same values, IL=±π/2I_{\rm L}=\pm\pi/2, occur in an impurity model in phases with regular low energy Fermi liquid behavior. Consequently the Luttinger integral can be taken to characterize these phases, and the quantum critical points separating them interpreted as topological.Comment: 5 pages 7 figure
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