8,919 research outputs found
Systems thinking: critical thinking skills for the 1990s and beyond
This pdf article discusses the need for teaching systems thinking and critical thinking skills. Systems thinking and systems dynamics are important for developing effective strategies to close the gap between the interdependent nature of our problems and our ability to understand them. This article calls for a clearer view of the nature of systems thinking and the education system into which it must be transferred. Educational levels: Graduate or professional
Solutions of the motion of synchronous satellites with arbitrary eccentricity and inclination
A first order, semianalytical theory for the long term motion of resonant satellites is presented. The theory is valid for all eccentricities and inclinations and for all commensurability ratios. The method allows the inclusion of all the zonal and tesseral harmonics as well as luni solar perturbations and radiation pressure. The method is applied to a synchronous satellite including only the J sub 2 and J sub 22 harmonics. Global, long term solutions for this problem, eccentricity, argument of perigee, and inclination are obtained
Timelike Compton scattering: exclusive photoproduction of lepton pairs
We investigate the exclusive photoproduction of a heavy timelike photon which
decays into a lepton pair, gamma p -> l+ l- p. This can be seen as the analog
of deeply virtual Compton scattering, and we argue that the two processes are
complementary for studying generalized parton distributions in the nucleon. In
an unpolarized experiment the angular distribution of the leptons readily
provides access to the real part of the Compton amplitude. We estimate the
possible size of this effect in kinematics where the Compton process should be
dominated by quark exchange.Comment: 31 pages, 17 figure
On baryon-antibaryon coupling to two photons
We discuss recent claims that may be described
by a generalized parton picture. We propose that quark-hadron duality provides
a justification for the effective dominance of the "handbag" diagram assumed in
recent literature, and that handbag diagrams may dominate phenomena in
kinematic regions far more extensive than that might be expected from pQCD
alone.Comment: 11 pages, 2 eps figures, minor modifications made, version to appear
on Phys. Lett.
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