Soil contamination level with 239+240Pu of Lublin region was determined using the alpha spectrometric method. Results were compared with similar data from the study performed 15 year earlier. Decrease in total 239+240Pu concentration and reducing quantity of Chernobyl fraction (up to almost negligible value of 1 %) has been observed in upper soil layer. Determination of 239+240Pu concentration ...

Reverse-time migration (Baysal et al., 1984) has some potential advantages with respect to downward-continuation migration. It can migrate overturned and prismatic reflections even in the presence of strong lateral velocity variations (Biondi, 2002). It also models the amplitude of the transmitted wavefield more accurately than downward-continuation in the presence of sharp interfaces. However,...

Common-azimuth migration (CAM) is a 3-D prestack depth migration technique based on the wave equation (Biondi and Palacharla, 1996). It exploits the intrinsic narrow-azimuth nature of marine data to reduce its dimensionality and thus manages to cut the computational cost of 3-D imaging significantly enough to compete with Kirchhoff methods. Based on a recursive extrapolation of the recorded wav...

Most eukaryotic cells sense and respond to the mechanical properties of their surroundings. This can strongly influence their collective behavior in embryonic development, tissue function, and wound healing. We use a deformable substrate to measure collective behavior in cell motion due to substrate mediated cell-cell interactions. We quantify spatial and temporal correlations in migration velo...

Fluid-flow-driven particle migration through porous networks reflects the interplay between various particle-level forces, the relative size between migrating particles and pore constrictions, and the spatial variability of the velocity field. Experimental evidence shows that particle migration in radial fluid flow results in selfstabilizing annular clogging patterns when the particle size appr...

In this paper I discuss three different methods to speed up midpoint-offset domain downward continuation based migration. I compare the migration results with the more standard downward continuation method. I show that a factor of two speed up is achievable with little discernible loss in image quality. In addition I show that for velocity analysis purposes a factor of three to four speed up is...

Recent observations show a clear correlation between the probability of hosting a planet and the metallicity of the parent star. Since radial velocity surveys are biased, however, towards detecting planets with short orbital periods, the probabilitymetallicity correlation could merely reflect a dependence of migration rates on metallicity. We investigated the possibility, but find no basis to s...

Reflections and refractions from wide-angle, densely sampled, multi channel streamer data are transformed automatically to the slowness-depth domain using a downward continuation algorithm. The method may be used to rapidly obtain velocity functions for use in pre-stack depth migration processes. Incorporation of the reflection data has the potential to produce velocity images in complex geolog...

We develop a new one-way wave prestack depth migration method called Fourier integration (FI) method which uses the exact extrapolation operator and the exact velocity model without any approximations or assumptions. The work is performed on a CUDA (Compute Unified Device Architecture) based Graphic Processing Unit (GPU). Compared to the traditional one way wave method, the GPU version FI metho...

The Stolt migration extension to a varying velocity case (Stolt stretch) implies describing a vertical heterogeneity by a constant parameter (W ). This paper exploits the connection between modified dispersion relations and traveltime approximations to derive an explicit expression for W . The expression provides theoretically the highest possible accuracy within the Stolt stretch framework. Ap...