Our MR-based attenuation correction method offers similar correction accuracy as offered by segmented CT. According to the specialists involved in the blind study, these differences do not affect the diagnostic value of the PET images.

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The diffusive motion of O atoms adsorbed on Ru(0001) was observed on the atomic scale by scanning tunneling microscopy with temporal resolution of ഠ10 ms at room temperature. From statistical analysis of the changes of the atom configurations in sequences of more than 1000 images, mean residence times of oxygen atoms in the neighborhood of other oxygen atoms were extracted. The residence times vary by more than 1 order of magnitude over distances of three lattice constants, indicating the necessity of including the lateral interaction in modeling collective phenomena such as surface diffusion or reactions. [S0031-9007(99)09081-X]

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