24,797 research outputs found
Interplanetary scintillation in Jovian decametric radiation
Interplanetary scintillation in Jupiter decametric radiatio
A very low frequency radio astronomy observatory on the Moon
Because of terrestrial ionospheric absorption, very little is known of the radio sky beyond 10 m wavelength. An extremely simple, low cost very low frequency radio telescope is proposed, consisting of a large array of short wires laid on the lunar surface, each wire equipped with an amplifier and a digitizer, and connected to a common computer. The telescope could do simultaneous multifrequency observations of much of the visible sky with high resolution in the 10 to 100 m wavelength range, and with lower resolution in the 100 to 1000 m range. It would explore structure and spectra of galactic and extragalactic point sources, objects, and clouds, and would produce detailed quasi-three-dimensional mapping of interstellar matter within several thousand parsecs of the Sun
Near-field horizontal and vertical earthquake ground motions
Strong-motion attenuation relationships are presented for peak ground acceleration, spectral acceleration, energy density, maximum absolute input energy for horizontal and vertical directions and for the ratio of vertical to horizontal of these ground motion parameters. These equations were derived using a worldwide dataset of 186 strong-motion records recorded with 15 km of the surface projection of earthquakes between Ms = 5:8 and 7.8. The effect of local site conditions and focal mechanism is included in some of these equations
World-sheet Instantons via the Myers Effect and N=1^* Quiver Superpotentials
In this note we explore the stringy interpretation of non-perturbative
effects in N=1^* deformations of the A_{k-1} quiver models. For certain types
of deformations we argue that the massive vacua are described by Nk fractional
D3-branes at the orbifold polarizing into k concentric 5-brane spheres each
carrying fractional brane charge. The polarization of the D3-branes induces a
polarization of D-instantons into string world-sheets wrapped on the Myers
spheres. We show that the superpotentials in these models are indeed generated
by these world-sheet instantons. We point out that for certain parameter values
the condensates yield the exact superpotential for a relevant deformation of
the Klebanov-Witten conifold theory.Comment: 24 pages, JHEP, some small errors and typos correcte
From integrated to expedient: an adaptive framework for river basin management in developing countries
Water resource management / River basin management / Water allocation / Case studies / Africa South of Sahara / Great Ruaha River Basin
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