10,448 research outputs found
A Statistical Model of Magnetic Islands in a Large Current Layer
We develop a statistical model describing the dynamics of magnetic islands in
very large current layers that develop in space plasma. Two parameters
characterize the island distribution: the flux contained in the island and the
area it encloses. We derive an integro-differential evolution equation for this
distribution function, based on rules that govern the small-scale generation of
secondary islands, the rates of island growth, and island merging. Our
numerical solutions of this equation produce island distributions relevant to
the magnetosphere and corona. We also derive and analytically solve a
differential equation for large islands that explicitly shows the role merging
plays in island growth.Comment: 4 pages, 3 figure
SETI science working group report
This report covers the initial activities and deliberations of a continuing working group asked to assist the SETI Program Office at NASA. Seven chapters present the group's consensus on objectives, strategies, and plans for instrumental R&D and for a microwave search for extraterrestrial in intelligence (SETI) projected for the end of this decade. Thirteen appendixes reflect the views of their individual authors. Included are discussions of the 8-million-channel spectrum analyzer architecture and the proof-of-concept device under development; signal detection, recognition, and identification on-line in the presence of noise and radio interference; the 1-10 GHz sky survey and the 1-3 GHz targeted search envisaged; and the mutual interests of SETI and radio astronomy. The report ends with a selective, annotated SETI reading list of pro and contra SETI publications
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