The Experts below are selected from a list of 102081 Experts worldwide ranked by ideXlab platform
Daniel Svensek - One of the best experts on this subject based on the ideXlab platform.
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Confined chiral polymer nematics : ordering and spontaneous condensation
Europhysics letters, 2016Co-Authors: Rudolf Podgornik, Daniel SvensekAbstract:We investigate condensation of a long confined chiral nematic polymer inside a spherical enclosure, mimicking condensation of DNA inside a viral capsid. The Landau-de Gennes nematic free-energy Ansatz appropriate for nematic polymers allows us to study the condensation process in detail with different boundary conditions at the enclosing wall that simulate repulsive and attractive polymer-Surface interactions. By increasing the chirality, we observe a transformation of the toroidal condensate into a Closed Surface with an increasing genus, in some respects akin to the ordered domain formation observed in cryo-microscopy of bacteriophages.
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confined chiral polymer nematics ordering and spontaneous condensation
arXiv: Soft Condensed Matter, 2012Co-Authors: Daniel Svensek, Rudolf PodgornikAbstract:We investigate condensation of a long confined chiral nematic polymer inside a spherical enclosure, mimicking condensation of DNA inside a viral capsid. The Landau-de Gennes nematic free energy {\sl Ansatz} appropriate for nematic polymers allows us to study the condensation process in detail with different boundary conditions at the enclosing wall that simulate repulsive and attractive polymer-Surface interactions. Increasing the chirality, we observe a transformation of the toroidal condensate into a Closed Surface with an increasing genus, akin to the ordered domain formation observed in cryo-microscopy of bacteriophages.
Lluis Garrido - One of the best experts on this subject based on the ideXlab platform.
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affine coordinate based parametrized active contours for 2d and 3d image segmentation
International Conference on Computer Vision, 2014Co-Authors: Q Xue, Laura Igual, A Berenguel, Marite Guerrieri, Lluis GarridoAbstract:In this paper, we present a new framework for image segmentation based on parametrized active contours. The contour and the points of the image space are parametrized using a set of reduced control points that form a Closed polygon in two dimensional problems and a Closed Surface in three dimensional problems. The active contour evolves by moving the control points. The parametrization, that uses mean value coordinates, stems from the techniques used in computer graphics to animate virtual models. The proposed framework allows to easily formulate region-based energies as the one proposed by Chan and Vese in both two and three dimensional segmentation problems. We show the usefulness of our approach with several experiments.
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active contour segmentation with affine coordinate based parametrization
International Conference on Computer Vision Theory and Applications, 2014Co-Authors: Q Xue, Laura Igual, A Berenguel, Marite Guerrieri, Lluis GarridoAbstract:In this paper, we present a new framework for image segmentation based on parametrized active contours. The contour and the points of the image space are parametrized using a set of reduced control points that have to form a Closed polygon in two dimensional problems and a Closed Surface in three dimensional problems. By moving the control points, the active contour evolves. We use mean value coordinates as the parametrization tool for the interface, which allows to parametrize any point of the space, inside or outside the Closed polygon or Surface. Region-based energies such as the one proposed by Chan and Vese can be easily implemented in both two and three dimensional segmentation problems. We show the usefulness of our approach with several experiments.
Rudolf Podgornik - One of the best experts on this subject based on the ideXlab platform.
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Confined chiral polymer nematics : ordering and spontaneous condensation
Europhysics letters, 2016Co-Authors: Rudolf Podgornik, Daniel SvensekAbstract:We investigate condensation of a long confined chiral nematic polymer inside a spherical enclosure, mimicking condensation of DNA inside a viral capsid. The Landau-de Gennes nematic free-energy Ansatz appropriate for nematic polymers allows us to study the condensation process in detail with different boundary conditions at the enclosing wall that simulate repulsive and attractive polymer-Surface interactions. By increasing the chirality, we observe a transformation of the toroidal condensate into a Closed Surface with an increasing genus, in some respects akin to the ordered domain formation observed in cryo-microscopy of bacteriophages.
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confined chiral polymer nematics ordering and spontaneous condensation
arXiv: Soft Condensed Matter, 2012Co-Authors: Daniel Svensek, Rudolf PodgornikAbstract:We investigate condensation of a long confined chiral nematic polymer inside a spherical enclosure, mimicking condensation of DNA inside a viral capsid. The Landau-de Gennes nematic free energy {\sl Ansatz} appropriate for nematic polymers allows us to study the condensation process in detail with different boundary conditions at the enclosing wall that simulate repulsive and attractive polymer-Surface interactions. Increasing the chirality, we observe a transformation of the toroidal condensate into a Closed Surface with an increasing genus, akin to the ordered domain formation observed in cryo-microscopy of bacteriophages.
Marion Darbas - One of the best experts on this subject based on the ideXlab platform.
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approximate local dirichlet to neumann map for three dimensional time harmonic elastic waves
Computer Methods in Applied Mechanics and Engineering, 2015Co-Authors: Stephanie Chaillat, Marion Darbas, Frederique Le LouerAbstract:It has been proven that the knowledge of an accurate approximation of the Dirichlet-to-Neumann (DtN) map is useful for a large range of applications in wave scattering problems. We are concerned in this paper with the construction of an approximate local DtN operator for time-harmonic elastic waves. The main contributions are the following. First, we derive exact operators using Fourier analysis in the case of an elastic half-space. These results are then extended to a general three-dimensional smooth Closed Surface by using a local tangent plane approximation. Next, a regularization step improves the accuracy of the approximate DtN operators and a localization process is proposed. Finally, a first application is presented in the context of the On-Surface Radiation Conditions method. The efficiency of the approach is investigated for various obstacle geometries at high frequencies.
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generalized combined field integral equations for the iterative solution of the three dimensional helmholtz equation
Mathematical Modelling and Numerical Analysis, 2007Co-Authors: Xavier Antoine, Marion DarbasAbstract:This paper addresses the derivation of new second-kind Fredholm combined field integral equations for the Krylov iterative solution of tridimensional acoustic scattering problems by a smooth Closed Surface. These integral equations need the introduction of suitable tangential square-root operators to regularize the formulations. Existence and uniqueness occur for these formulations. They can be interpreted as generalizations of the well-known Brakhage-Werner [A. Brakhage and P. Werner, Arch. Math. 16 (1965) 325-329] and Combined Field Integral Equations (CFIE) [R.F. Harrington and J.R. Mautz, Arch. Elektron. Ubertragungstech (AEU) 32 (1978) 157-164]. Finally, some numerical experiments are performed to test their efficiency.
Q Xue - One of the best experts on this subject based on the ideXlab platform.
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affine coordinate based parametrized active contours for 2d and 3d image segmentation
International Conference on Computer Vision, 2014Co-Authors: Q Xue, Laura Igual, A Berenguel, Marite Guerrieri, Lluis GarridoAbstract:In this paper, we present a new framework for image segmentation based on parametrized active contours. The contour and the points of the image space are parametrized using a set of reduced control points that form a Closed polygon in two dimensional problems and a Closed Surface in three dimensional problems. The active contour evolves by moving the control points. The parametrization, that uses mean value coordinates, stems from the techniques used in computer graphics to animate virtual models. The proposed framework allows to easily formulate region-based energies as the one proposed by Chan and Vese in both two and three dimensional segmentation problems. We show the usefulness of our approach with several experiments.
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active contour segmentation with affine coordinate based parametrization
International Conference on Computer Vision Theory and Applications, 2014Co-Authors: Q Xue, Laura Igual, A Berenguel, Marite Guerrieri, Lluis GarridoAbstract:In this paper, we present a new framework for image segmentation based on parametrized active contours. The contour and the points of the image space are parametrized using a set of reduced control points that have to form a Closed polygon in two dimensional problems and a Closed Surface in three dimensional problems. By moving the control points, the active contour evolves. We use mean value coordinates as the parametrization tool for the interface, which allows to parametrize any point of the space, inside or outside the Closed polygon or Surface. Region-based energies such as the one proposed by Chan and Vese can be easily implemented in both two and three dimensional segmentation problems. We show the usefulness of our approach with several experiments.
