No abstract

The knowledge of structure of proteins, protein derived compounds and RNA structures in eukaryotic cell is mandatory to understand the functions of these macromolecules.With recent development of Direct Electron Detector Device (DDD) camera and application of maximum likelihood algorithms in volume reconstruction,cryo Electron Microscopy (cryo-EM) enables us to visualize the macromolecules in nearly physiological state. The current resolution limit of cryo-EM can be improved further by applying novel and effective signal processing algorithms after the EM workflow. In this work, a signal processing method has been developed to enhance the resolution of the EM volume through volume restoration techniques. We have proposed a novel technique to estimate the volume degradation function of the volume reconstruction system from the noise-only subvolumes of the observed EM volume. Then the volume is restored (utilizing the estimated volume degradation function) using a combination of regularized Richardson-Lucy and Wiener Deconvolution techniques. In addition to volume restoration, we have employed spatial de-noising techniques utilizing various morphological filters to reduce noise outside the main molecular structure. The experimental results demonstrate that the resolution (evaluated by ourier Shell Correlation curve) and visual quality of the EM volume can be significantly improved using our proposed technique.

T his is the second part to [1], which summarized the first two editions of the IEEE Signal Processing Cup. The perspectives of the competition organizers and the student finalists are given in this column. Shaping The FirST Topic In May 2013, Dimitri van de Ville, the chair of the IEEE Bioimaging and Signal Processing Technical Committee (BISP TC) [2] forwarded an e-mail to the members of the committee calling for proposals for the IEEE Signal Processing Society's (SPS's) First Signal Processing Cup. The idea was to promote signal processing, particularly its applications to solve real-world problems, among undergraduate students. I work at the Instruct Image Processing Center [3] in Madrid, Spain, a reference center for image processing in structural biology. The call for proposals was a perfect match between the need to achieve higher resolution in the three-dimensional (3-D) reconstructions of biological macromolecules and the possibility to explore the recently introduced ideas in the areas of superresolution, image restoration, and denoising. The possibility of having students all over the world trying to tackle this problem sounded attractive and challenging. So, with the support of the BISP TC, the Instruct Image Processing Center submitted a proposal for enhancing the resolution achieved by electron microscopes in the elucidation of the structure of single particles. Students could be as creative as they wished as long as the resolution