1,177 research outputs found

    Analysis of the effectiveness of industrial R and D

    Get PDF
    The criteria used by private industry in evaluating and selecting proposed research and development projects for implementation, and also in determining which R and D facilities are to be acquired were investigated. Conceptual and practical issues inherent in any quantitative analysis of the contribution of R and D to economic growth were identified in order to assist NASA in developing approaches for analzying the economic implication of its own R and D efforts

    Perturbation of Tunneling Processes by Mechanical Degrees of Freedom in Mesoscopic Junctions

    Get PDF
    We investigate the perturbation in the tunneling current caused by non-adiabatic mechanical motion in a mesoscopic tunnel junction. A theory introduced by Caroli et al. \cite{bi1,bi2,bi3} is used to evaluate second order self-energy corrections for this non-equilibrium situation lacking translational invariance. Inelastic signatures of the mechanical degrees of freedom are found in the current-voltage I(V)I(V) characteristics. These give rise to sharp features in the derivative spectrum, d2I/dV2d^2I/dV^2.Comment: 22 pages LaTeX + 3 uuencoded PS picture

    The Canonical Model of a Singular Curve

    Full text link
    We give refined statements and modern proofs of Rosenlicht's results about the canonical model C' of an arbitrary complete integral curve C. Notably, we prove that C and C' are birationally equivalent if and only if C is nonhyperelliptic, and that, if C is nonhyperelliptic, then C' is equal to the blowup of C with respect to the canonical sheaf \omega. We also prove some new results: we determine just when C' is rational normal, arithmetically normal, projectively normal, and linearly normal.Comment: 28 pages, no figures, IV Congresso Iberoamericano de Geometria Complex

    Democratic cultural policy : democratic forms and policy consequences

    Get PDF
    The forms that are adopted to give practical meaning to democracy are assessed to identify what their implications are for the production of public policies in general and cultural policies in particular. A comparison of direct, representative, democratic elitist and deliberative versions of democracy identifies clear differences between them in terms of policy form and democratic practice. Further elaboration of these differences and their consequences are identified as areas for further research

    Spin polarization of the Ar* 2p−11/2 4s and 2p−11/2 3d resonant Auger decay

    Full text link
    The spin-resolved Auger decay of the Ar 2p−11/2 3d state was measured at moderate energy resolution and compared with the decay of the 2p−11/2 4s. The former shows a lower transferred spin polarization and a similar, if not higher, dynamical spin polarization, supporting the statement that a fully resolved spectrum is not a necessary condition for observing dynamical spin polarization. An interpretation of the spin polarization as configuration interaction induced effect in the final ionic state leads to partial agreement with our relativistic distorted wave calculation utilizing a 36 configuration state function basis set. Comparison of the experimental and numerical results leads to ambiguities for at least one Auger line. A hypothetical, qualitative interpretation is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58121/2/b7_17_012.pd

    New Experimental Limits on Macroscopic Forces Below 100 Microns

    Full text link
    Results of an experimental search for new macroscopic forces with Yukawa range between 5 and 500 microns are presented. The experiment uses 1 kHz mechanical oscillators as test masses with a stiff conducting shield between them to suppress backgrounds. No signal is observed above the instrumental thermal noise after 22 hours of integration time. These results provide the strongest limits to date between 10 and 100 microns, improve on previous limits by as much as three orders of magnitude, and rule out half of the remaining parameter space for predictions of string-inspired models with low-energy supersymmetry breaking. New forces of four times gravitational strength or greater are excluded at the 95% confidence level for interaction ranges between 200 and 500 microns.Comment: 25 Pages, 7 Figures: Minor Correction

    Ground State Vortex Lattice Structures in d-wave Superconductors

    Get PDF
    We show in a realistic dx2y2d_{x^{2}-y^{2}} symmetry gap model for a cuprate superconductor that the clean vortex lattice has discontinuous structural transitions (at and near T=0), as a function of the magnetic field BB along the c-axis. The transitions arise from the singular nonlocal and anisotropic susceptibility of the dx2y2d_{x^{2}-y^{2}} superconductor to the perturbation caused by supercurrents associated with vortices. The susceptibility, due to virtual Dirac quasiparticle-hole excitation, is calculated carefully, and leads to a ground state transition for the triangular lattice from an orientation along one of the crystal axis to one at 45o^o to them, i.e, along the gap zero direction. The field scale is seen to be 5 Tesla (Δ0/ta)2Φ0 \sim (\Delta_{0}/ta)^{2}\Phi_{0}, where Δ0\Delta_{0} is the gap maximum, tt is the nearest neighbour hopping, aa is the lattice constant, and Φ0\Phi_{0} is the flux quantum. At much higher fields (28T\sim 28T) there is a discontinuous transition to a centred square structure. The source of the differences from existing calculations, and experimental observability are discussed, the latter especially in view of the very small (a few degrees KK per vortex) differences in the ground state energy.Comment: To be published in Phys. Rev.
    corecore