Optical diffraction patterns obtained from electron micrograph images showing crystalline or repeating units can provide confirmatory and even new information regarding substructure (7, 10, 11) . Essentially, an image of a portion of an electron micrograph is used as a two-dimensional grating to produce a diffraction pattern . This pattern of spots can indicate major and minor periodicities wit...

Electron micrographs of inseminated eggs of Hydroides hexagonus previously had shown that in the immediate vicinity of the penetrating spermatozoön a small portion of the vitelline membrane regularly was absent, and it had been suggested that this area was a hole made by lytic activity of the individual spermatozoön during the course of its passage through the membrane. This deduction would rec...

A heavily distorted high resolution electron microscopy (HREM) image of a cesium-niobium oxide-fluoride sample wa reconstructed by crystallographic image processing (CIP). In the reconstructed image, showing 4bm symmetry, all metal atom were clearly seen with correct contrast, whereas in the original micrograph the fourfold symmetry was lost and only sore areas could be interpreted in terms of ...

Single particle reconstruction is often employed for 3-D reconstruction of diverse macromolecules. However, the algorithm requires a good initial guess from a priori information to guarantee the convergence to the correct solution. This paper describes a novel model free 3-D reconstruction algorithm by employing the symmetry and sparsity of unknown structure. Especially, we develop an accurate ...