27 research outputs found

    Uniqueness for the electrostatic inverse boundary value problem with piecewise constant anisotropic conductivities

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    We discuss the inverse problem of determining the, possibly anisotropic, conductivity of a body ΩRn\Omega\subset\mathbb{R}^{n} when the so-called Neumann-to-Dirichlet map is locally given on a non empty curved portion Σ\Sigma of the boundary Ω\partial\Omega. We prove that anisotropic conductivities that are \textit{a-priori} known to be piecewise constant matrices on a given partition of Ω\Omega with curved interfaces can be uniquely determined in the interior from the knowledge of the local Neumann-to-Dirichlet map

    Lipschitz stability for the electrostatic inverse boundary value problem with piecewise linear conductivities

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    We consider the electrostatic inverse boundary value problem also known as electrical impedance tomography (EIT) for the case where the conductivity is a piecewise linear function on a domain ΩRn\Omega\subset\mathbb{R}^n and we show that a Lipschitz stability estimate for the conductivity in terms of the local Dirichlet-to-Neumann map holds true.Comment: 28 pages. arXiv admin note: text overlap with arXiv:1405.047

    Determining an anisotropic conductivity by boundary measurements: Stability at the boundary

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    We consider the inverse problem of determining, the possibly anisotropic, conductivity of a body \Omega ⊂Rn, n ≥3, by means of the so-called local Neumann-to-Dirichlet map on a curved portion \Sigma of its boundary ∂\Omega . Motivated by the uniqueness result for piecewise constant anisotropic conductivities proved in Inverse Problems 33 (2018), 125013, we provide a Hölder stability estimate on \Sigma when the conductivity is a-priori known to be a constant matrix near \Sigma

    Clinical veterinary boron neutron capture therapy (BNCT) studies in dogs with head and neck cancer: Bridging the gap between translational and clinical studies

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    Translational Boron Neutron Capture Therapy (BNCT) studies performed by our group and clinical BNCT studies worldwide have shown the therapeutic efficacy of BNCT for head and neck cancer. The present BNCT studies in veterinary patients with head and neck cancer were performed to optimize the therapeutic efficacy of BNCT, contribute towards exploring the role of BNCT in veterinary medicine, put in place technical aspects for an upcoming clinical trial of BNCT for head and neck cancer at the RA-6 Nuclear Reactor, and assess the feasibility of employing the existing B2 beam to treat large, deep-seated tumors. Five dogs with head and neck cancer with no other therapeutic option were treated with two applications of BNCT mediated by boronophenyl-alanine (BPA) separated by 3–5 weeks. Two to three portals per BNCT application were used to achieve a potentially therapeutic dose over the tumor without exceeding normal tissue tolerance. Clinical and Computed Tomography results evidenced partial tumor control in all cases, with slight-moderate mucositis, excellent life quality, and prolongation in the survival time estimated at recruitment. These exploratory studies show the potential value of BNCT in veterinary medicine and contribute towards initiating a clinical BNCT trial for head and neck cancer at the RA-6 clinical facility.Fil: Schwint, Amanda Elena. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Monti Hughes, Andrea. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Garabalino, Marcela Alejandra. Comisión Nacional de Energía Atómica; ArgentinaFil: Santa Cruz, Gustavo Alberto. Comisión Nacional de Energía Atómica; ArgentinaFil: González, Sara Josefina. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia Física (Centro Atómico Constituyentes). Proyecto Tandar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Longhino, Juan Manuel. Comisión Nacional de Energía Atómica; ArgentinaFil: Provenzano, Lucas. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigación y Aplicaciones No Nucleares. Gerencia Física (Centro Atómico Constituyentes). Proyecto Tandar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Oña, Paulina. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Instituto de Tecnologías Nucleares para la Salud; ArgentinaFil: Rao, Monica. Hospital Veterinario; ArgentinaFil: Cantarelli, María de los Ángeles. Hospital Veterinario; ArgentinaFil: Leiras, Andrea. No especifíca;Fil: Olivera, María Silvina. Comisión Nacional de Energía Atómica; ArgentinaFil: Trivillin, Verónica Andrea. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Departamento de Radiobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alessandrini, Paula. No especifíca;Fil: Brollo, Fabricio Raul. Comisión Nacional de Energía Atómica; ArgentinaFil: Boggio, Esteban Fabián. Comisión Nacional de Energía Atómica; ArgentinaFil: Costa, Hernan. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Instituto de Tecnologías Nucleares para la Salud; ArgentinaFil: Ventimiglia, Romina. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Instituto de Tecnologías Nucleares para la Salud; ArgentinaFil: Binia, Sergio. Comisión Nacional de Energía Atómica. Gerencia de Área de Aplicaciones de la Tecnología Nuclear. Instituto de Tecnologías Nucleares para la Salud; ArgentinaFil: Pozzi, Emiliano César Cayetano. Comisión Nacional de Energía Atómica; ArgentinaFil: Nievas, Susana Isabel. Comisión Nacional de Energía Atómica; ArgentinaFil: Santa Cruz, Iara S.. Comisión Nacional de Energía Atómica; Argentin

    Determining conductivity with special aniostropy by boundary measurements

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    We prove results of uniqueness and stability at the boundary for the inverse problem of electrical impedance tomography in the presence of possibly anisotropic conduct.ivities. We assume that the unknown conductivity has the forrn A = A(x, a(x)), where a(x) is an unknown scalar function and A(x, t) is a given matrix-valued function. We also deduce results of uniqueness in the interior among conductivities A obtained by piecewise analytic perturbations of the scalar term a

    Inverse problems for the Helmholtz equation with Cauchy data : reconstruction with conditional well-posedness driven iterative regularization

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    In this paper, we study the performance of Full Waveform Inversion (FWI) from time-harmonic Cauchy data via conditional well-posedness driven iterative regularization. The Cauchy data can be obtained with dual sensors measuring the pressure and the normal velocity. We define a novel misfit functional which, adapted to the Cauchy data, allows the independent location of experimental and computational sources. The conditional well-posedness is obtained for a hierarchy of subspaces in which the inverse problem with partial data is Lipschitz stable. Here, these subspaces yield piecewise linear representations of the wave speed on given domain partitions. Domain partitions can be adaptively obtained through segmentation of the gradient. The domain partitions can be taken as a coarsening of an unstructured tetrahedral mesh associated with a finite element discretization of the Helmholtz equation. We illustrate the effectiveness of the iterative regularization through computational experiments with data in dimension three. In comparison with earlier work, the Cauchy data do not suffer from eigenfrequencies in the configurations

    EIT in a layered anisotropic medium

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    We consider the inverse problem in geophysics of imaging the sub- surface of the Earth in cases where a region below the surface is known to be formed by strata of different materials and the depths and thicknesses of the strata and the (possibly anisotropic) conductivity of each of them need to be identified simultaneously. This problem is treated as a special case of the inverse problem of determining a family of nested inclusions in a medium \u3a9 82 Rn, n 65 3

    Lipschitz stability for a piecewise linear Schrodinger potential from local Cauchy data

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    We consider the inverse boundary value problem of determining the potential q in the equation \u394u+qu=0 in \u3a9 82Rn, from local Cauchy data. A result of global Lipschitz stability is obtained in dimension n\u2a7e3 for potentials that are piecewise linear on a given partition of \u3a9. No sign, nor spectrum condition on q is assumed, hence our treatment encompasses the reduced wave equation \u394u+k2c 122u=0 at fixed frequency k
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