Affine motion of 2d incompressible fluids surrounded by vacuum and flows in SL(2,R){\rm SL}(2,{\mathbb R})

The affine motion of two-dimensional (2d) incompressible fluids surrounded by vacuum can be reduced to a completely integrable and globally solvable Hamiltonian system of ordinary differential equations for the deformation gradient in ${\rm SL}(2,{\mathbb R})$. In the case of perfect fluids, the motion is given by geodesic flow in ${\rm SL}(2,{\mathbb R})$ with the Euclidean metric, while for magnetically conducting fluids (MHD), the motion is governed by a harmonic oscillator in ${\rm SL}(2,{\mathbb R})$. A complete classification of the dynamics is given including rigid motions, rotating eddies with stable and unstable manifolds, and solutions with vanishing pressure. For perfect fluids, the displacement generically becomes unbounded, as $t\to\pm\infty$. For MHD, solutions are bounded and generically quasi-periodic and recurrent.Comment: 60 pages, 7 figure

ECONOMIC VALUATION OF SOME WETLAND OUTPUTS OF MUD LAKE, MINNESOTA-SOUTH DAKOTA

The objective of this study was to estimate some economic values of Mud Lake, a managed, lacustrine wetland on the Minnesota-South Dakota border. Several outputs of Mud Lake were identified and an economic value was estimated for each. Flood control was valued at approximately $440 per acre, based on dollar damages prevented; water supply, using public utility revenues, was valued at$94 per acre; fish/wildlife habitat, recreation, and aesthetics were valued at about $21 per acre using the Contingent Valuation Method; and corrective expenditures were used to evaluate water quality at a negative per acre value of$180. When capitalized at 6 percent, the estimated total annual value of these four outputs is $6,250 per acre. These values can assist managers and policy makers in making decisions regarding the opportunity costs of Mud Lake management options or of wetland alterations or preservation. These snapshot values of Mud Lake "at the margin" are estimated under the assumption that all other wetlands and water resources in the region are unchanged.wetland, outputs, economic valuation, flood control, water supply, water quality, recreation, aesthetics, fish/wildlife habitat, contingent valuation method, Resource /Energy Economics and Policy, Land Economics/Use,

Ratiocination, Romanticism and Realism in the Detective Story: A Study of Poe, Doyle and Hammet

A thesis presented to the faculty of the School of Humanities at Morehead State University in partial fulfillment of the requirements for the Degree of Master of Arts by Timothy Jay Roberts on December 3, 1984