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Cone Beam Computerized Tomography (CBCT) and Positron Emission Tomography (PET) Scans are medical imaging devices that require solving ill-posed inverse problems. The models considered come directly from the physics of the acquisition devices, and take into account the specificity of the (Poisson) noise. We propose various fast numerical schemes to compute(More)
Let (Xt, t ≥ 0) be an α-stable random walk with values in Z d. Let lt(x) = t 0 δx(Xs)ds be its local time. For p > 1, not necessarily integer, It = x l p t (x) is the so-called p-fold self-intersection local time of the random walk. When p(d − α) < d, we derive precise logarithmic asymptotics of the probability P [It ≥ rt] for all scales rt E [It]. Our(More)
Our goal is to study the multifractal properties of functions of a given family which have few non vanishing wavelet coefficients. They are indeed somehow " sparse " signals. We compute at each point the pointwise Hölder exponent of these functions and also their local L p regularity, computing the so-called p-exponent. We prove that in the general case the(More)
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