1,771 research outputs found

    Interaction of united states objectives in space with those on earth program of policy studies in science and technology paper no. 2

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    Interaction of United States objectives in space with those on eart

    Science in national policy - a preliminary inquiry paper no. 1

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    Science in national polic

    Surgical Management of Spinal Epidural Disease: An Update

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    Management of spinal cord compression from metastatic malignant disease remains unsatisfactory. Results of surgical decompression are at best less than those of radiation therapy alone. However, new surgical approaches now focus on removing the anterior-situated tumor tissue which produces neural compression in about 85% of the cases. The results of these procedures that allow removal of the ventrally compressing tumor show significant improvement in the management of patients with spinal epidural disease. We review the surgical strategy of these new approaches and the attendant results

    Soft pion theorem for hard near threshold pion production

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    We prove new soft pion theorem for the near threshold pion production by a hard electromagnetic probe. This theorem relates various near threshold pion production amplitudes to the nucleon distribution amplitudes. The new soft pion theorem is in a good agreement with the SLAC data for F_2^p(W,Q^2) for W^2 < 1.4 GeV^2 and 7 < Q^2 < 30.7 GeV^2.Comment: 9 pages, revised version, more general analysi

    What explains the uneven take-up of ISO 14001 at the global level?: a panel-data analysis

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    Since its release in the mid-1990s, close to 37 000 facilities have been certified to ISO 14001, the international voluntary standard for environmental management systems. Yet, despite claims that the standard can be readily adapted to very different corporate and geographic settings, its take-up has been highly geographically variable. This paper contributes to a growing body of work concerned with explaining the uneven diffusion of ISO 14001 at the global level. Drawing from the existing theoretical and empirical literature we develop a series of hypotheses about how various economic, market, and regulatory factors influence the national count of ISO 14001 certifications. These hypotheses are then tested using econometric estimation techniques with data for a panel of 142 developed and developing countries. We find that per capita ISO 14001 counts are positively correlated with income per capita, stock of foreign direct investment, exports of goods and services to Europe and Japan, and pressure from civil society. Conversely, productivity and levels of state intervention are negatively correlated. The paper finishes by offering a number of recommendations to policymakers concerned with accelerating the diffusion of voluntary environmental standards

    On the Nucleon Distribution Amplitude: The Heterotic Solution

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    We present a new nucleon distribution amplitude which amalgamates features of the Chernyak-Ogloblin-Zhitnitsky model with those of the Gari-Stefanis model. This "heterotic" solution provides the possibility to have asymptotically a small ratio \hbox{GMn/GMp0.1\vert G_{M}^{n}\vert/G_{M}^{p}\le 0.1}, while fulfilling most of the sum-rule requirements up to the third order. Using this nucleon distribution amplitude we calculate the electromagnetic and weak nucleon form factors, the transition form factor γpΔ+\gamma p \Delta^{+} and the decay widths of the charmonium levels 3S1^3S_{1}, 3P1^3P_{1}, and 3P2^3P_{2} into ppˉp\bar p. The agreement with the available data is remarkable in all cases.Comment: 15 pages, RUB-TPII-21/92 Preprin

    Transverse momentum dependence of semi-inclusive pion production

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    Cross sections for semi-inclusive electroproduction of charged pions (π±\pi^{\pm}) from both proton and deuteron targets were measured for 0.2<x<0.50.2<x<0.5, 2<Q2<42<Q^2<4 GeV2^2, 0.3<z<10.3<z<1, and Pt2<0.2P_t^2<0.2 GeV2^2. For Pt<0.1P_t<0.1 GeV, we find the azimuthal dependence to be small, as expected theoretically. For both π+\pi^+ and π\pi^-, the PtP_t dependence from the deuteron is found to be slightly weaker than from the proton. In the context of a simple model, this implies that the initial transverse momenta width of dd quarks is larger than for uu quarks and, contrary to expectations, the transverse momentum width of the favored fragmentation function is larger than the unfavored one.Comment: 15 pages, 4 figures. Fit form changed to include Cahn effect Minor revisions. Added one new figur

    The Onset of Quark-Hadron Duality in Pion Electroproduction

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    A large data set of charged-pion electroproduction from both hydrogen and deuterium targets has been obtained spanning the low-energy residual-mass region. These data conclusively show the onset of the quark-hadron duality phenomenon, as predicted for high-energy hadron electroproduction. We construct several ratios from these data to exhibit the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark-to- pion production mechanisms.Comment: 11 pages, 3 figures, accepted in Phys. Rev. Lett. Tables adde

    Probing Short Range Nucleon Correlations in High Energy Hard Quasielastic pd Reactions

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    We show that the strong dependence of the amplitude for NNNN hard scattering on the collision energy can be used to magnify the effects of short range nucleon correlations in quasielastic pdpd scattering. Under specific kinematical conditions the effect of initial and final state interactions can be accounted for by rescaling the cross section calculated within the plane wave impulse approximation. The feasibility to investigate the role of relativistic effects in the deuteron wave function is demonstrated by comparing the predictions of different formalisms. Binding effects due to short range correlations in deuteron are discussed as well.Comment: 18 pages (LaTex) + 10 postscript figs (available on request
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