Strong refraction of waves in the migration velocity model introduces kinematic artifacts coherent events not corresponding to actual reflectors into the image volumes 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 eve...

Acquisition and processing of multifold groundpenetrating radar (GPR) data enable detailed measurements of lateral velocity variability. The velocities constrain interpretation of subsurface materials and lead to significant improvement in image accuracy when coupled with prestack depth migration (PSDM). Reflection tomography in the postmigration domain was introduced in the early 1990s for vel...

Cell migration through 3D extracellular matrices is critical to the normal development of tissues and organs and in disease processes, yet adequate analytical tools to characterize 3D migration are lacking. Here, we quantified the migration patterns of individual fibrosarcoma cells on 2D substrates and in 3D collagen matrices and found that 3D migration does not follow a random walk. Both 2D an...

BACKGROUND Although the adhesive mechanisms underlying the capture and immobilization of circulating neutrophils in inflamed blood vessels have been well described, factors controlling the subsequent migration of neutrophils over and through the blood vessel endothelium are poorly understood. Directional rearrangement of the actin cytoskeleton within the neutrophil, along with modulation of int...

Conventional velocity analysis applied to images produced by wave-equation migration with a cross-correlation imaging condition makes use either of moveout information from space-lags or of focusing information from time-lags. However, more robust velocity estimation methods can be designed to take advantage simultaneously of the moveout and focusing information provided by the migrated images....

Atomic resolution electron microscopy has been used to obtain images of moving dislocation kinks on partial dislocations at 600 ±C in silicon. Video difference images are used to obtain direct estimates of kink velocity. Observations of kink delay at obstacles, thought to be oxygen atoms at the dislocation core, yield unpinning energies and parameters of the obstacle theory of kink motion. The ...

Sensitivity kernels for wave equation based migration velocity analysis in local angle-domain are formulated. These sensitivity kernels serve as operators to backproject the residual moveout in local angle-domain common image gathers to migration models for velocity updating. To validate the theoretical formulation, we directly measure sensitivity kernels using a perturb-measuring approach. For...