منابع مشابه
Comparison of 3He ventilation images at 1.5T and 3T: increased apparent heterogeneity due to susceptibility gradients
Introduction: The spin polarization of hyperpolarized media such as He, C and Xe does not depend on the static magnetic field strength B0, hence higher B0 field strength does not necessarily result in a better signal to noise ratio. While theoretical predictions exist [1], the signal to noise ratio (SNR) for imaging of hyperpolarized nuclei will depend on the size of the object and the RF coils...
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Macroscopic magnetic field inhomogeneities severely limit sensitivity of blood oxygenation level-dependent (BOLD) functional MRI (fMRI) in frontal and central brain regions close to brain stem. A single-shot multiecho echo-planar imaging method (TurboPEPSI) was developed that combines quantitative T(2)* mapping with gradient compensation of local susceptibility inhomogeneities in multiple volum...
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The level set representation of shapes is useful for shape evolution and is widely used for the minimization of energies with respect to shapes. Many algorithms consider energies depending explicitly on the signed distance function (SDF) associated with a shape, and differentiate these energies with respect to the SDF directly in order to make the level set representation evolve. This framework...
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Linnaeus, upon travelling north from southern Sweden, was struck by the differences between that colder land and his homeland. The differences in the composition of species begged explanation. Ever since (and probably before), naturalists, ecologists, and biogeographers have sought to understand why species and the communities they make up differ from place to place. Why does body size, both wi...
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Combining aqueous multiphase systems (AMPS) and magnetic levitation (MagLev) provides a method to produce hybrid gradients in apparent density. AMPS—solutions of different polymers, salts, or surfactants that spontaneously separate into immiscible but predominantly aqueous phases—offer thermodynamically stable steps in density that can be tuned by the concentration of solutes. MagLev—the levita...
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ژورنال
عنوان ژورنال: Botanical Gazette
سال: 1920
ISSN: 0006-8071
DOI: 10.1086/332628