The Experts below are selected from a list of 144762 Experts worldwide ranked by ideXlab platform

Kevin M Bennett - One of the best experts on this subject based on the ideXlab platform.

  • water diffusion heterogeneity index in the human brain is insensitive to the orientation of Applied Magnetic Field gradients
    Magnetic Resonance in Medicine, 2006
    Co-Authors: Kevin M Bennett, James S Hyde, Kathleen M Schmainda
    Abstract:

    The alpha diffusion-weighted imaging (DWI) method was developed to study heterogeneous water diffusion in the human brain using Magnetic resonance imaging (MRI). An advantage of this model is that it does not require an assumption about the shape of the intravoxel distribution of apparent diffusion rates, and it has a calculable relationship to this distribution. The alpha-DWI technique is useful for detecting microstructural tissue changes associated with brain tumor invasion, and may be useful for directing therapy to invading tumor cells. In previous work, alpha-DWI was performed with Magnetic Field gradients Applied along a single direction in order to avoid artificially introducing a source of heterogeneity to the decay. However, it is known that restricted diffusion is anisotropic in the brain, and the alpha-DWI method must take this into account to be complete. In this work the relationship between the Applied Magnetic Field gradients and the fitted stretched-exponential model parameters was studied in the human brain. It was found the distributed diffusion coefficient (DDC) varies with the direction of Applied gradients, while the heterogeneity index alpha is relatively direction-insensitive. It is proposed that in clinical use, maps of alpha can be created using diffusion-weighting gradients Applied in a single direction that reflect the tissue heterogeneity.

  • water diffusion heterogeneity index in the human brain is insensitive to the orientation of Applied Magnetic Field gradients
    Magnetic Resonance in Medicine, 2006
    Co-Authors: Kevin M Bennett, James S Hyde, Kathleen M Schmainda
    Abstract:

    The α diffusion-weighted imaging (DWI) method was developed to study heterogeneous water diffusion in the human brain using Magnetic resonance imaging (MRI). An advantage of this model is that it does not require an assumption about the shape of the intravoxel distribution of apparent diffusion rates, and it has a calculable relationship to this distribution. The α-DWI technique is useful for detecting microstructural tissue changes associated with brain tumor invasion, and may be useful for directing therapy to invading tumor cells. In previous work, α-DWI was performed with Magnetic Field gradients Applied along a single direction in order to avoid artificially introducing a source of heterogeneity to the decay. However, it is known that restricted diffusion is anisotropic in the brain, and the α-DWI method must take this into account to be complete. In this work the relationship between the Applied Magnetic Field gradients and the fitted stretched-exponential model parameters was studied in the human brain. It was found the distributed diffusion coefficient (DDC) varies with the direction of Applied gradients, while the heterogeneity index α is relatively direction-insensitive. It is proposed that in clinical use, maps of α can be created using diffusion-weighting gradients Applied in a single direction that reflect the tissue heterogeneity. Magn Reson Med, 2006. Published 2006 Wiley-Liss, Inc.

Kathleen M Schmainda - One of the best experts on this subject based on the ideXlab platform.

  • water diffusion heterogeneity index in the human brain is insensitive to the orientation of Applied Magnetic Field gradients
    Magnetic Resonance in Medicine, 2006
    Co-Authors: Kevin M Bennett, James S Hyde, Kathleen M Schmainda
    Abstract:

    The alpha diffusion-weighted imaging (DWI) method was developed to study heterogeneous water diffusion in the human brain using Magnetic resonance imaging (MRI). An advantage of this model is that it does not require an assumption about the shape of the intravoxel distribution of apparent diffusion rates, and it has a calculable relationship to this distribution. The alpha-DWI technique is useful for detecting microstructural tissue changes associated with brain tumor invasion, and may be useful for directing therapy to invading tumor cells. In previous work, alpha-DWI was performed with Magnetic Field gradients Applied along a single direction in order to avoid artificially introducing a source of heterogeneity to the decay. However, it is known that restricted diffusion is anisotropic in the brain, and the alpha-DWI method must take this into account to be complete. In this work the relationship between the Applied Magnetic Field gradients and the fitted stretched-exponential model parameters was studied in the human brain. It was found the distributed diffusion coefficient (DDC) varies with the direction of Applied gradients, while the heterogeneity index alpha is relatively direction-insensitive. It is proposed that in clinical use, maps of alpha can be created using diffusion-weighting gradients Applied in a single direction that reflect the tissue heterogeneity.

  • water diffusion heterogeneity index in the human brain is insensitive to the orientation of Applied Magnetic Field gradients
    Magnetic Resonance in Medicine, 2006
    Co-Authors: Kevin M Bennett, James S Hyde, Kathleen M Schmainda
    Abstract:

    The α diffusion-weighted imaging (DWI) method was developed to study heterogeneous water diffusion in the human brain using Magnetic resonance imaging (MRI). An advantage of this model is that it does not require an assumption about the shape of the intravoxel distribution of apparent diffusion rates, and it has a calculable relationship to this distribution. The α-DWI technique is useful for detecting microstructural tissue changes associated with brain tumor invasion, and may be useful for directing therapy to invading tumor cells. In previous work, α-DWI was performed with Magnetic Field gradients Applied along a single direction in order to avoid artificially introducing a source of heterogeneity to the decay. However, it is known that restricted diffusion is anisotropic in the brain, and the α-DWI method must take this into account to be complete. In this work the relationship between the Applied Magnetic Field gradients and the fitted stretched-exponential model parameters was studied in the human brain. It was found the distributed diffusion coefficient (DDC) varies with the direction of Applied gradients, while the heterogeneity index α is relatively direction-insensitive. It is proposed that in clinical use, maps of α can be created using diffusion-weighting gradients Applied in a single direction that reflect the tissue heterogeneity. Magn Reson Med, 2006. Published 2006 Wiley-Liss, Inc.

Susumu Shima - One of the best experts on this subject based on the ideXlab platform.

  • a study of Magnetic particles behavior by magneto cosserat continuum theory
    IEEE Transactions on Magnetics, 2000
    Co-Authors: Hidetoshi Kotera, Harunori Kitahara, Susumu Shima
    Abstract:

    By implementing the magneto-Cosserat continuum theory in FEM scheme, it is possible to simulate Magnetic alignment in powders with Magnetic anisotropy during compaction in an Applied Magnetic Field. We thereby analyze the relationship between the direction of Magnetic Field and compaction process, such as cross compaction and parallel compaction. The rotation of the axes is thus calculated at various conditions of Applied Magnetic Field. In our previous study, Cosserat constant /spl beta/ was given arbitrarily. The method to calculate the Cosserat constant /spl beta/ is proposed and its effect on the rotation of the particles' easy axes is discussed. As a demonstration of the developed method, Magnetic particles' alignment during compaction in an Applied Magnetic Field is simulated. The calculated results are in good agreement with the experimental ones.

  • cosserat continuum theory to simulate microscopic rotation of Magnetic powder in Applied Magnetic Field
    International Journal of Mechanical Sciences, 2000
    Co-Authors: Hidetoshi Kotera, Muneo Sawada, Susumu Shima
    Abstract:

    Numerical method based on the Cosserat continuum theory is proposed for simulating behavior of a Magnetic powder in an Applied Magnetic Field. The Maxwell stress is induced in the Magnetic powder. During powder forming process in the Magnetic Field, the Magnetic particles are thus rotated and transferred by both mechanical and Magnetic interaction. To simulate such powder behavior, we formulate a finite element equation considering Maxwell stress based on the Cosserat continuum theory of compressible plasticity. The powder behavior with Magnetic alignment during compaction in Magnetic Field is simulated by the proposed method and the effect of couple-stress on the powder behavior is discussed.

  • Magnetic cosserat continuum theory to simulate behavior of Magnetic powder during compaction in Applied Magnetic Field
    Metals and Materials, 1998
    Co-Authors: Hidetoshi Kotera, Muneo Sawada, Susumu Shima
    Abstract:

    Numerical method based on the Cosserat continuum theory is proposed for simulating behavior of a Magnetic powder in an Applied Magnetic Field. The Maxwell stress is induced in the Magnetic powder. During powder forming process in the Magnetic Field, the Magnetic particles are thus rotated and transferred by both mechanical and Magnetic interaction. To simulate such powder behavior, we formulate a finite element equation considering Maxwell stress based on the Cosserat continuum theory of compressible plasticity. The powder behavior with Magnetic alignment during compaction in Magnetic Field is simulated by the proposed method and the effect of couple-stress on the powder behaviour is discussed.

Zhifeng Liu - One of the best experts on this subject based on the ideXlab platform.

  • Magnetic memory signals variation induced by Applied Magnetic Field and static tensile stress in ferroMagnetic steel
    Journal of Magnetism and Magnetic Materials, 2016
    Co-Authors: Haihong Huang, Cheng Yang, Zhengchun Qian, Gang Han, Zhifeng Liu
    Abstract:

    Abstract Stress can induce a spontaneous Magnetic Field in ferroMagnetic steel under the excitation of geoMagnetic Field. In order to investigate the impact of Applied Magnetic Field and tensile stress on variation of the residual Magnetic signals on the surface of ferroMagnetic materials, static tensile tests of Q235 structural steel were carried out, with the normal component of the residual Magnetic signals, H p ( y ), induced by Applied Magnetic Fields with different intensities measured through the tensile tests. The H p ( y ), its slope coefficient K S and maximum gradient K max changing with the Applied Magnetic Field H and tensile stress were observed. Results show that the magnitude of H p ( y ) and its slope coefficient K S increase linearly with the increase of stress in the elastic deformation stage. Under yield stress, H p ( y ) and K S reach its maximum, and then decrease slightly with further increase of stress. Applied Magnetic Field affects the magnitude of H p ( y ) instead of changing the signal curve′s profile; and the magnitude of H p ( y ), K S , K max and the change rate of K S increase with the increase of Applied Magnetic Field. The phenomenon is also discussed from the viewpoint of Magnetic charge in ferroMagnetic materials.

  • residual Magnetic Field variation induced by Applied Magnetic Field and cyclic tensile stress
    Ndt & E International, 2014
    Co-Authors: Haihong Huang, Jieyan Yao, Zhifeng Liu
    Abstract:

    Abstract Magnetic memory testing (MMT) method is a novel non-destructive testing technique due to its unique advantages of stress concentration identification and early damage detection for ferroMagnetic materials. However, a thorough understanding of the impact of exciting Magnetic source and cyclic stress on the residual Magnetic Field variation has not been clearly addressed. The surface Magnetic memory signal H p ( y ) induced by Applied Magnetic Field and cyclic tensile stress was measured throughout the fatigue process. The correlation of H p ( y ) and its gradient K changes with loading cycles and Applied Magnetic Field intensity H reported. The results show that Applied Magnetic Field can only change the magnitude of MMT signal instead of changing the H p ( y ) curve׳s profile. The H p ( y ) value increases with the increase of the H , and the K value is approximately linear to the H . The maximum gradient K max indicating the degree of stress concentration increases with the increase of either stress cycles or H . The phenomenon was also discussed from the view of the Magnetic dipole in a ferromagnet.

Chisa Hotta - One of the best experts on this subject based on the ideXlab platform.

  • finite temperature thermodynamic properties of spin 1 nematics in an Applied Magnetic Field
    Physical Review B, 2020
    Co-Authors: Katsuhiro Tanaka, Chisa Hotta
    Abstract:

    We study numerically the thermodynamic properties of the spin nematic phases in a Magnetic Field in the spin-1 bilinear-biquadratic model. When the Field is Applied, the phase transition temperature initially goes up and then decreases rapidly toward zero, which is detected by the peak shift in the specific heat. The underlying mechanism of the reentrant behavior is the entropic effect. In a weak Field the high temperature paraMagnetic phase rapidly loses its entropy while the ferroquadrupolar nematic phase remains robust by modifying the shape of the ferroquadrupolar moment. This feature serves as a fingerprint of generic ferroquadrupolar phases, while it is not observed for the case of antiferroquadrupoles.