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The effect of spike time dependent plasticity on activity patterns in the basal ganglia

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Kinematic Artifacts in Prestack Depth Migration Christiaan C. Stolk ∗and William W. Symes † ABSTRACT Strong refraction of waves in the migration velocity model introduces kinematic artifacts - coherent events not corresponding to actual reflectors - into the image vol- umes produced by prestack depth migration applied to individual data bins. Because individual bins are migrated independently, the migration has no access to the bin component of slowness. This loss of slowness information permits events to migrate along multiple incident-reflected ray pairs, thus introducing spurious coherent events into the image volume. This pathology occurs for all common binning strategies, including common source, common offset, and common scattering angle. Since the artifacts move out with bin parameter, their effect on the final stacked image is min- imal, provided that the migration velocity model is kinematically correct. However common image gathers may exhibit energetic primary events with substantial residual moveout, even with kinematically accurate migration velocity model. ∗Centre de Mathe´matiques, Ecole Polytechnique, 91128 Palaiseau Cedex, France, email [email protected] †The Rice Inversion Project, Department of Computational and Applied Mathematics, Rice University, Houston TX 77005-1892 USA, email [email protected] 1 INTRODUCTION Unstacked migrated image volumes are the raw material of migration velocity analysis. Migration velocities are assessed and estimated by means of the semblance principle: if the velocity is correct, then images formed from different data bins within the unstacked data volume should be the same, at least with respect to phase. Thus image gathers (migrated traces sharing a common surface location), displayed in depth vs. bin parame- ter, should appear flat. Velocity analysis adjusts migration velocity iteratively to flatten image gathers, the flatness being assessed either directly through visual inspection,

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