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
Interaction of United States objectives in space with those on eart
Surgical Management of Spinal Epidural Disease: An Update
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
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
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
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{}, 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 and the decay widths
of the charmonium levels , , and into .
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
Cross sections for semi-inclusive electroproduction of charged pions
() from both proton and deuteron targets were measured for
, GeV, , and GeV. For
GeV, we find the azimuthal dependence to be small, as expected
theoretically. For both and , the 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
quarks is larger than for 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
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
We show that the strong dependence of the amplitude for hard scattering
on the collision energy can be used to magnify the effects of short range
nucleon correlations in quasielastic 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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