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E. Mark Haacke - One of the best experts on this subject based on the ideXlab platform.

  • theory of nmr signal Behavior in magnetically inhomogeneous tissues the static dephasing regime
    Magnetic Resonance in Medicine, 1994
    Co-Authors: Dmitriy A. Yablonskiy, E. Mark Haacke
    Abstract:

    This paper is devoted to a theory of the NMR signal Behavior in biological tissues in the presence of static magnetic field inhomogeneities. We have developed an approach that analytically describes the NMR signal in the static dephasing regime where diffusion phenomena may be ignored. This approach has been applied to evaluate the NMR signal in the presence of a blood vessel network (with an application to functional imaging), bone marrow (for two specific trabecular structures, asymmetrical and columnar) and a ferrite contrast agent. All investigated systems have some Common Behavior. If the echo time TE is less than a known characteristic time tc for a given system, then the signal decays exponentially with an argument which depends quadratically on TE. This is equivalent to an R2* relaxation rate which is a linear function of TE. In the opposite case, when TE is greater than tc, the NMR signal follows a simple exponential decay and the relaxation rate does not depend on the echo time. For this time interval, R2* is a linear function of a) volume fraction ζ occupied by the field-creating objects, b) magnetic field B0 or just the objects' magnetic moment for ferrite particles, and c) susceptibility difference Δχ between the objects and the medium.

  • theory of nmr signal Behavior in magnetically inhomogeneous tissues the static dephasing regime
    Magnetic Resonance in Medicine, 1994
    Co-Authors: Dmitriy A. Yablonskiy, E. Mark Haacke
    Abstract:

    This paper is devoted to a theory of the NMR signal Behavior in biological tissues in the presence of static magnetic field inhomogeneities. We have developed an approach that analytically describes the NMR signal in the static dephasing regime where diffusion phenomena may be ignored. This approach has been applied to evaluate the NMR signal in the presence of a blood vessel network (with an application to functional imaging), bone marrow (for two specific trabecular structures, asymmetrical and columnar) and a ferrite contrast agent. All investigated systems have some Common Behavior. If the echo time TE is less than a known characteristic time tc for a given system, then the signal decays exponentially with an argument which depends quadratically on TE. This is equivalent to an R2* relaxation rate which is a linear function of TE. In the opposite case, when TE is greater than tc, the NMR signal follows a simple exponential decay and the relaxation rate does not depend on the echo time. For this time interval, R2* is a linear function of a) volume fraction sigma occupied by the field-creating objects, b) magnetic field Bo or just the objects' magnetic moment for ferrite particles, and c) susceptibility difference delta chi between the objects and the medium.

Dmitriy A. Yablonskiy - One of the best experts on this subject based on the ideXlab platform.

  • theory of nmr signal Behavior in magnetically inhomogeneous tissues the static dephasing regime
    Magnetic Resonance in Medicine, 1994
    Co-Authors: Dmitriy A. Yablonskiy, E. Mark Haacke
    Abstract:

    This paper is devoted to a theory of the NMR signal Behavior in biological tissues in the presence of static magnetic field inhomogeneities. We have developed an approach that analytically describes the NMR signal in the static dephasing regime where diffusion phenomena may be ignored. This approach has been applied to evaluate the NMR signal in the presence of a blood vessel network (with an application to functional imaging), bone marrow (for two specific trabecular structures, asymmetrical and columnar) and a ferrite contrast agent. All investigated systems have some Common Behavior. If the echo time TE is less than a known characteristic time tc for a given system, then the signal decays exponentially with an argument which depends quadratically on TE. This is equivalent to an R2* relaxation rate which is a linear function of TE. In the opposite case, when TE is greater than tc, the NMR signal follows a simple exponential decay and the relaxation rate does not depend on the echo time. For this time interval, R2* is a linear function of a) volume fraction ζ occupied by the field-creating objects, b) magnetic field B0 or just the objects' magnetic moment for ferrite particles, and c) susceptibility difference Δχ between the objects and the medium.

  • theory of nmr signal Behavior in magnetically inhomogeneous tissues the static dephasing regime
    Magnetic Resonance in Medicine, 1994
    Co-Authors: Dmitriy A. Yablonskiy, E. Mark Haacke
    Abstract:

    This paper is devoted to a theory of the NMR signal Behavior in biological tissues in the presence of static magnetic field inhomogeneities. We have developed an approach that analytically describes the NMR signal in the static dephasing regime where diffusion phenomena may be ignored. This approach has been applied to evaluate the NMR signal in the presence of a blood vessel network (with an application to functional imaging), bone marrow (for two specific trabecular structures, asymmetrical and columnar) and a ferrite contrast agent. All investigated systems have some Common Behavior. If the echo time TE is less than a known characteristic time tc for a given system, then the signal decays exponentially with an argument which depends quadratically on TE. This is equivalent to an R2* relaxation rate which is a linear function of TE. In the opposite case, when TE is greater than tc, the NMR signal follows a simple exponential decay and the relaxation rate does not depend on the echo time. For this time interval, R2* is a linear function of a) volume fraction sigma occupied by the field-creating objects, b) magnetic field Bo or just the objects' magnetic moment for ferrite particles, and c) susceptibility difference delta chi between the objects and the medium.

D Vlasenko - One of the best experts on this subject based on the ideXlab platform.

V Lipunov - One of the best experts on this subject based on the ideXlab platform.

Changsong Zhou - One of the best experts on this subject based on the ideXlab platform.

  • The synchronization of chaotic systems
    Physics Reports, 2002
    Co-Authors: Stefano Boccaletti, Jurgen Kurths, Grigory V. Osipov, D. L. Valladares, Changsong Zhou
    Abstract:

    Abstract Synchronization of chaos refers to a process wherein two (or many) chaotic systems (either equivalent or nonequivalent) adjust a given property of their motion to a Common Behavior due to a coupling or to a forcing (periodical or noisy). We review major ideas involved in the field of synchronization of chaotic systems, and present in detail several types of synchronization features: complete synchronization, lag synchronization, generalized synchronization, phase and imperfect phase synchronization. We also discuss problems connected with characterizing synchronized states in extended pattern forming systems. Finally, we point out the relevance of chaos synchronization, especially in physiology, nonlinear optics and fluid dynamics, and give a review of relevant experimental applications of these ideas and techniques.