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Hardware, Especially Gradient Magnetic Fields
2008I am often asked why I bother to teach about the “nuts and bolts” of the MRI scanner system. After all, with the exception of physicists and engineers who are specifically interested in dealing with and perhaps modifying the hardware components of the scanner, virtually every MR user will leave the upkeep of the system to professional service personnel.
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Vertical gradients of sunspot magnetic fields
Solar Physics, 1983In this paper, we describe results of a Solar Maximum Mission (SMM) guest investigation to determine vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields. Both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight ...
M. J. Hagyard +8 more
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CHAPTER 5. Magnetic Field Gradients
2016Magnetic field gradients are an integral component in all MRI and NMR systems. The first part of this chapter describes the different design methods that can be used to produce gradients with high linearity, high efficiency and low eddy currents. Challenges that have to be faced include heating from the very large currents present in the gradient coils
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Electric Field Gradient Effects on Magnetic Susceptibility
2004Abstract A general expression for the magnetic susceptibility of a molecule in the presence of a time-independent, spatially uniform magnetic field, and a non-uniform electric field with a uniform gradient is discussed. The molecular response can be described by magnetic susceptibility polarizability tensors that depend on the choice of the origin ...
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Fields and gradients in multipolar magnets
Journal of Applied Physics, 1986This paper describes the two-dimensional field generated by an M pole electromagnet of cylindrical symmetry. By individually controlling the currents on each pole, it is possible to rotate the direction of the field around the axis of the cylinder. Gradients of any order can also be generated.
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A unilateral magnet with an extended constant magnetic field gradient
Journal of Magnetic Resonance, 2010Unilateral magnetic resonance (UMR) has become, in different research areas, a powerful tool to interrogate samples of arbitrary size. Numerous designs have been suggested in the literature to produce the desired magnetic field distributions, including designs which feature constant magnetic field gradients suitable for diffusion and profiling ...
Juan C, García-Naranjo +3 more
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Radiofrequency magnetic field gradient echoes have reduced sensitivity to susceptibility gradients
Magnetic Resonance Imaging, 1995The amplitudes of gradient-echoes produced using static field gradients are sensitive to diffusion of tissue water during the echo evolution time. Gradient-echoes have been used to produce MR images in which image intensity is proportional to the self-diffusion coefficient of water. However, such measurements are subject to error due to the presence of
G, Karczmar, J, River, A P, Koretsky
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Journal of Magnetic Resonance, 2008
Probes capable of generating short high intensity pulsed magnetic field gradients are commonly used in diffusion studies of systems with very short T(2). Traditional methods of calibrating magnetic field gradients present unique challenges at ultrahigh field strengths and are often inapplicable.
Yadav, Nirbhay N. (S24980) +2 more
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Probes capable of generating short high intensity pulsed magnetic field gradients are commonly used in diffusion studies of systems with very short T(2). Traditional methods of calibrating magnetic field gradients present unique challenges at ultrahigh field strengths and are often inapplicable.
Yadav, Nirbhay N. (S24980) +2 more
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Two-Dimensional Excitons in Large Magnetic Field Gradients
physica status solidi (a), 2000Inhomogeneous magnetic fields are used to exert a magnetic force on two-dimensional excitons. The large field gradients are produced by positioning a thin magnetized stripe of dysprosium on top of a semi-magnetic CdMnTe/CdMgTe quantum well. By measuring the photoluminescence energy and intensity, spatially resolved with μm resolution, the actual value ...
Pulizzi, F. +5 more
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Portable Magnetic Field and Gradient Meter
Review of Scientific Instruments, 1958A portable instrument for measuring magnetic fields and field gradients is described. The measurements depend on comparing the alternating emf's induced in two search coils oscillated synchronously at about 3 cps through angles of less than 3°, one in the field to be measured and the other in the reference field of a permanent magnet in the instrument.
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