Showing papers by "Alessandro Foi published in 2023"

Volumetric Filtering for Shot Gather Interpolation in Swath Seismic Acquisition

Abstract: Due to environmental and economic constraints inherent to seismic exploration, there are often missing shotpoints and receivers that degrade the resolution of the final seismic image. Hence, sophisticated interpolation techniques are required for the recovery of dense and uniform spatial sampling. Recent approaches improve the interpolation by adopting robust models through denoisers. We introduce a 3-D shot gather interpolation method that jointly considers a sparse prior and a regularization induced by a multichannel volumetric denoiser. The proposed volumetric regularization uses collaborative filters that perform denoising through transform-domain shrinkage of a group of similar seismic cubes extracted from a land seismic acquisition. This grouping and collaborative filtering paradigm exploit the local correlation present in each cube and the nonlocal correlation between different cubes. Experiments on the Stratton 3-D survey show that the proposed method can interpolate 3-D shot gathers in an orthogonal seismic recording from a swath geometry, outperforming methods based on 2-D denoisers and 5-D seismic data reconstruction in terms of root mean square error and the recovery of seismic reflections.

Iterative immunostaining combined with expansion microscopy and image processing reveals nanoscopic network organization of nuclear lamina

Abstract: Investigation of nuclear lamina architecture relies on super-resolved microscopy. However, epitope accessibility, labeling density, and detection precision of individual molecules pose challenges within the molecularly crowded nucleus. We developed iterative indirect immunofluorescence (IT–IF) staining approach combined with expansion microscopy (ExM) and structured illumination microscopy to improve super-resolution microscopy of subnuclear nanostructures like lamins. We prove that ExM is applicable in analyzing highly compacted nuclear multiprotein complexes such as viral capsids and provide technical improvements to ExM method including 3D-printed gel casting equipment. We show that in comparison to conventional immunostaining, IT-IF results in a higher signal-to-background –ratio and a mean fluorescence intensity by improving the labeling density. Moreover, we present a signal processing pipeline for noise estimation, denoising, and deblurring to aid in quantitative image analyses and provide this platform for the microscopy imaging community. Finally, we show the potential of signal-resolved IT–IF in quantitative super-resolution ExM imaging of nuclear lamina and reveal nanoscopic details of the lamin network organization - a prerequisite for studying intranuclear structural co-regulation of cell function and fate. (Words: 175)