C. J. Niche

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We address the study of decay rates of solutions to dissipative equations. The characterization of these rates is given for a wide class of linear systems by the decay character, which is a number associated to the initial datum that describes its behavior near the origin in frequency space. We then use the decay character and the Fourier Splitting method(More)
We address the decay of the norm of weak solutions to the 2D dissipative quasi-geostrophic equation. When the initial data θ0 is in L only, we prove that the L norm tends to zero but with no uniform rate, that is, there are solutions with arbitrarily slow decay. For θ0 in L ∩ L, with 1 ≤ p < 2, we are able to obtain a uniform decay rate in L. We also prove(More)
In this article, we prove two formulas for the topological entropy of an F-optical Hamiltonian flow induced by H ∈ C∞(M, R), where F is a Lagrangian distribution. In these formulas, we calculate the topological entropy as the exponential growth rate of the average of the determinant of the differential of the flow, restricted to the Lagrangian distribution(More)
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