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Guido Gerig - One of the best experts on this subject based on the ideXlab platform.

  • a statistical shape model of Individual Fiber tracts extracted from diffusion tensor mri
    Medical Image Computing and Computer-Assisted Intervention, 2004
    Co-Authors: Isabelle Corouge, Sylvain Gouttard, Guido Gerig
    Abstract:

    Diffusion Tensor MRI has become the preferred imaging modality to explore white matter structure and brain connectivity in vivo. Conventional region of interest analysis and voxel-based comparison does not make use of the geometric properties of Fiber tracts. This paper explores shape modelling of major Fiber bundles. We describe tracts, represented as clustered sets of curves of similar shape, by a shape prototype swept along a space trajectory. This approach can naturally describe white matter structures observed either as bundles dispersing towards the cortex or tracts defined as dense patterns of parallel Fibers. Sets of streamline curves obtained from tractography are clustered, parametrized and aligned with a similarity transform. An average curve and eigenmodes of shape variation describe a compact statistical shape model. Reconstruction by sweeping the template along the trajectory results in a simplified model of a tract. Feasibility is demonstrated by modelling callosal and cortico-spinal fasciculi of two different subjects.

  • A Statistical Shape Model of Individual Fiber Tracts Extracted from Diusion
    2004
    Co-Authors: Tensor Mri, Sylvain Gouttard, Isabelle Corouge, Guido Gerig
    Abstract:

    Diusion Tensor MRI has become the preferred imaging modality to explore white matter structure and brain connectivity in vivo. Conventional region of interest analysis and voxel-based comparison does not make use of the geometric properties of Fiber tracts. This pa- per explores shape modelling of major Fiber bundles. We describe tracts, represented as clustered sets of curves of similar shape, by a shape proto- type swept along a space trajectory. This approach can naturally describe white matter structures observed either as bundles dispersing towards the cortex or tracts defined as dense patterns of parallel Fibers. Sets of stream- line curves obtained from tractography are clustered, parametrized and aligned with a similarity transform. An average curve and eigenmodes of shape variation describe a compact statistical shape model. Reconstruc- tion by sweeping the template along the trajectory results in a simplified model of a tract. Feasibility is demonstrated by modelling callosal and cortico-spinal fasciculi of two dierent subjects.

Ralf Busch - One of the best experts on this subject based on the ideXlab platform.

Robert Schennach - One of the best experts on this subject based on the ideXlab platform.

  • how xylan effects the breaking load of Individual Fiber Fiber joints and the single Fiber tensile strength
    Cellulose, 2015
    Co-Authors: Albrecht Miletzky, Wolfgang Johann Fischer, Caterina Czibula, Christian Teichert, Wolfgang Bauer, Robert Schennach
    Abstract:

    Bleached and unrefined softwood kraft Fibers were treated with aqueous solutions of xylans and potassium hydroxide (KOH) to vary the amount of xylan present on the Fiber surface and within the Fiber wall. This was done in order to directly measure the influence of xylan on the joint strength of Individual Fiber–Fiber joints as well as the tensile strength of Individual Fibers to determine the elastic modulus. The results were compared with two unbleached and unrefined softwood kraft pulps (Kappa 42 and 54). Additional xylan had a statistically significant effect on the mean values of the breaking load of Individual Fiber crossings. Moreover, the breaking load was strongly affected by the cooking time during pulping. However, no correlation between the optical bonded area and the joint strength was observed. The modulus of elasticity of Individual Fibers was not influenced by additional xylan or alkaline extraction. The elastic modulus was influenced more by chemical pulping and bleaching. The results indicate that additional xylan on the Fiber surface has a strength-enhancing effect on the joint strength Individual Fiber crossings which also depends on the distribution of xylan. On the other hand, the elasticity of a Fiber seems to be more influenced by the morphology and the composition of the Fiber walls, especially in the secondary S2 wall.

  • How xylan effects the breaking load of Individual Fiber–Fiber joints and the single Fiber tensile strength
    Cellulose, 2014
    Co-Authors: Albrecht Miletzky, Wolfgang Johann Fischer, Caterina Czibula, Christian Teichert, Wolfgang Bauer, Robert Schennach
    Abstract:

    Bleached and unrefined softwood kraft Fibers were treated with aqueous solutions of xylans and potassium hydroxide (KOH) to vary the amount of xylan present on the Fiber surface and within the Fiber wall. This was done in order to directly measure the influence of xylan on the joint strength of Individual Fiber–Fiber joints as well as the tensile strength of Individual Fibers to determine the elastic modulus. The results were compared with two unbleached and unrefined softwood kraft pulps (Kappa 42 and 54). Additional xylan had a statistically significant effect on the mean values of the breaking load of Individual Fiber crossings. Moreover, the breaking load was strongly affected by the cooking time during pulping. However, no correlation between the optical bonded area and the joint strength was observed. The modulus of elasticity of Individual Fibers was not influenced by additional xylan or alkaline extraction. The elastic modulus was influenced more by chemical pulping and bleaching. The results indicate that additional xylan on the Fiber surface has a strength-enhancing effect on the joint strength Individual Fiber crossings which also depends on the distribution of xylan. On the other hand, the elasticity of a Fiber seems to be more influenced by the morphology and the composition of the Fiber walls, especially in the secondary S2 wall.

  • Testing of Individual Fiber-Fiber joints under biaxial load and simultaneous analysis of deformation
    Nordic Pulp & Paper Research Journal, 2012
    Co-Authors: Wolfgang Johann Fischer, Wolfgang Bauer, Ulrich Hirn, Robert Schennach
    Abstract:

    SUMMARY: In this paper a novel direct method for mechanical testing of single Fibers and Fiber joints is presented. Additional to the measurement of joint strength it is also possible to investigate loading geometry, deformation during testing, bending stiffness of Fibers as well as bonding energy. Furthermore biaxial loading of Fiber-Fiber joints is possible. Initial experiments have shown that mode II and III shear strength of Fiber-Fiber joints can be measured with this setup. Initial results for Fibers and Fiber joints of unbleached softwood kraft pulp are presented. The resulting values are 1.1724·10 -9 to 3.8798·10 -11 Nm² for bending stiffness, 3.9180·10 -10 to 2.8793·10 -11 kJ/bond for bonding energy, 6.54 mN for mode II and 1.057 mN for mode III mean shear strength. Mode II mean shear strength under biaxial load with a preload of 20 mN perpendicular to the loading direction of the Fiber-Fiber joint was found to be 2.52 mN. These values are compared to results of other measurement techniques and discussed.

  • Joint strength measurements of Individual Fiber-Fiber bonds: an atomic force microscopy based method.
    Review of Scientific Instruments, 2012
    Co-Authors: Franz Schmied, Christian Teichert, Lisbeth Kappel, Ulrich Hirn, Robert Schennach
    Abstract:

    We are introducing a method to measure tensile strength of Individual Fiber-Fiber bonds within a breaking force range of 0.01 mN–1 mN as well as the energy consumed during breaking. Until now, such a method was not available. Using a conventional atomic force microscope and a specifically designed sample holder, the desired force and the breaking behavior can be analyzed by two different approaches. First, dynamic loading can be applied, where force-versus-distance curves are employed to determine the proportions of elastic energy and energy dissipated in the bond. Second, static loading is utilized to study viscoelastic behavior and calculate viscoelastic energy contributions. To demonstrate the capability of the proposed method, we are presenting results for breaking strength of kraft pulp Fiber-Fiber bonds in tensile opening mode. The procedure is by no means restricted to cellulose Fibers, it has the potential to quantify joint strength of micrometer-sized Fibers in general.

  • A novel method for the determination of bonded area of Individual Fiber-Fiber bonds
    Nordic Pulp & Paper Research Journal, 2009
    Co-Authors: Lisbeth Kappel, Wolfgang Bauer, Robert Schennach
    Abstract:

    87 Fiber-Fiber bonds from an unbleached and unbeaten softwood kraft pulp were analyzed. The statistical evaluation of the results showed that basic geometry (Fiber width and crossing angle) explain only 55% of bonded area. Incomplete bonding (holes and overlapping but unbonded edges) additionally account for 27% of the bonded area, while Fiber morphology only plays a minor role. This is a contradiction to the conventional theory that Fiber conformability controls the bonded area in paper. An explanation for this might be that one cannot rationalize the three-dimensional network of paper directly from twodimensional Fiber-Fiber bonds.

Isabelle Corouge - One of the best experts on this subject based on the ideXlab platform.

  • a statistical shape model of Individual Fiber tracts extracted from diffusion tensor mri
    Medical Image Computing and Computer-Assisted Intervention, 2004
    Co-Authors: Isabelle Corouge, Sylvain Gouttard, Guido Gerig
    Abstract:

    Diffusion Tensor MRI has become the preferred imaging modality to explore white matter structure and brain connectivity in vivo. Conventional region of interest analysis and voxel-based comparison does not make use of the geometric properties of Fiber tracts. This paper explores shape modelling of major Fiber bundles. We describe tracts, represented as clustered sets of curves of similar shape, by a shape prototype swept along a space trajectory. This approach can naturally describe white matter structures observed either as bundles dispersing towards the cortex or tracts defined as dense patterns of parallel Fibers. Sets of streamline curves obtained from tractography are clustered, parametrized and aligned with a similarity transform. An average curve and eigenmodes of shape variation describe a compact statistical shape model. Reconstruction by sweeping the template along the trajectory results in a simplified model of a tract. Feasibility is demonstrated by modelling callosal and cortico-spinal fasciculi of two different subjects.

  • A Statistical Shape Model of Individual Fiber Tracts Extracted from Diusion
    2004
    Co-Authors: Tensor Mri, Sylvain Gouttard, Isabelle Corouge, Guido Gerig
    Abstract:

    Diusion Tensor MRI has become the preferred imaging modality to explore white matter structure and brain connectivity in vivo. Conventional region of interest analysis and voxel-based comparison does not make use of the geometric properties of Fiber tracts. This pa- per explores shape modelling of major Fiber bundles. We describe tracts, represented as clustered sets of curves of similar shape, by a shape proto- type swept along a space trajectory. This approach can naturally describe white matter structures observed either as bundles dispersing towards the cortex or tracts defined as dense patterns of parallel Fibers. Sets of stream- line curves obtained from tractography are clustered, parametrized and aligned with a similarity transform. An average curve and eigenmodes of shape variation describe a compact statistical shape model. Reconstruc- tion by sweeping the template along the trajectory results in a simplified model of a tract. Feasibility is demonstrated by modelling callosal and cortico-spinal fasciculi of two dierent subjects.

Sylvain Gouttard - One of the best experts on this subject based on the ideXlab platform.

  • a statistical shape model of Individual Fiber tracts extracted from diffusion tensor mri
    Medical Image Computing and Computer-Assisted Intervention, 2004
    Co-Authors: Isabelle Corouge, Sylvain Gouttard, Guido Gerig
    Abstract:

    Diffusion Tensor MRI has become the preferred imaging modality to explore white matter structure and brain connectivity in vivo. Conventional region of interest analysis and voxel-based comparison does not make use of the geometric properties of Fiber tracts. This paper explores shape modelling of major Fiber bundles. We describe tracts, represented as clustered sets of curves of similar shape, by a shape prototype swept along a space trajectory. This approach can naturally describe white matter structures observed either as bundles dispersing towards the cortex or tracts defined as dense patterns of parallel Fibers. Sets of streamline curves obtained from tractography are clustered, parametrized and aligned with a similarity transform. An average curve and eigenmodes of shape variation describe a compact statistical shape model. Reconstruction by sweeping the template along the trajectory results in a simplified model of a tract. Feasibility is demonstrated by modelling callosal and cortico-spinal fasciculi of two different subjects.

  • A Statistical Shape Model of Individual Fiber Tracts Extracted from Diusion
    2004
    Co-Authors: Tensor Mri, Sylvain Gouttard, Isabelle Corouge, Guido Gerig
    Abstract:

    Diusion Tensor MRI has become the preferred imaging modality to explore white matter structure and brain connectivity in vivo. Conventional region of interest analysis and voxel-based comparison does not make use of the geometric properties of Fiber tracts. This pa- per explores shape modelling of major Fiber bundles. We describe tracts, represented as clustered sets of curves of similar shape, by a shape proto- type swept along a space trajectory. This approach can naturally describe white matter structures observed either as bundles dispersing towards the cortex or tracts defined as dense patterns of parallel Fibers. Sets of stream- line curves obtained from tractography are clustered, parametrized and aligned with a similarity transform. An average curve and eigenmodes of shape variation describe a compact statistical shape model. Reconstruc- tion by sweeping the template along the trajectory results in a simplified model of a tract. Feasibility is demonstrated by modelling callosal and cortico-spinal fasciculi of two dierent subjects.