6,593 research outputs found

    Assisting Community Foundations with Branding, Standards, and Marketing: Lessons Learned

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    Michigan has been intentional about growing community foundations since the late 1980s. Local efforts have been supported by the Council of Michigan Foundations with funding from the W.K. Kellogg Foundation. FERA (Formative Evaluation Research Associates), an independent evaluation group, and Williams Group, a strategic communications firm, have documented growth, identified supports and obstacles, and developed lessons learned. This document is part of a larger set of lessons learned across multiple state-wide initiatives about community foundation growth

    Lorentz Space Estimates for the Ginzburg-Landau Energy

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    In this paper we prove novel lower bounds for the Ginzburg-Landau energy with or without magnetic field. These bounds rely on an improvement of the "vortex balls construction" estimates by extracting a new positive term in the energy lower bounds. This extra term can be conveniently estimated through a Lorentz space norm, on which it thus provides an upper bound. The Lorentz space L2,∞L^{2,\infty} we use is critical with respect to the expected vortex profiles and can serve to estimate the total number of vortices and get improved convergence results.Comment: 52 pages, 1 figur

    Compressible, inviscid Rayleigh-Taylor instability

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    We consider the Rayleigh-Taylor problem for two compressible, immiscible, inviscid, barotropic fluids evolving with a free interface in the presence of a uniform gravitational field. After constructing Rayleigh-Taylor steady-state solutions with a denser fluid lying above the free interface with the second fluid, we turn to an analysis of the equations obtained from linearizing around such a steady state. By a natural variational approach, we construct normal mode solutions that grow exponentially in time with rate like e^{t \sqrt{\abs{\xi}}}, where ξ\xi is the spatial frequency of the normal mode. A Fourier synthesis of these normal mode solutions allows us to construct solutions that grow arbitrarily quickly in the Sobolev space HkH^k, which leads to an ill-posedness result for the linearized problem. Using these pathological solutions, we then demonstrate ill-posedness for the original non-linear problem in an appropriate sense. More precisely, we use a contradiction argument to show that the non-linear problem does not admit reasonable estimates of solutions for small time in terms of the initial data.Comment: 31 pages; v2: updated grant informatio

    Passive scalars, moving boundaries, and Newton's law of cooling

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    We study the evolution of passive scalars in both rigid and moving slab-like domains, in both horizontally periodic and infinite contexts. The scalar is required to satisfy Robin-type boundary conditions corresponding to Newton's law of cooling, which lead to nontrivial equilibrium configurations. We study the equilibration rate of the passive scalar in terms of the parameters in the boundary condition and the equilibration rates of the background velocity field and moving domain.Comment: 27 page
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