@article {2110, title = {Determination of signal-to-noise ratios and spectral SNRs in cryo-EM low-dose imaging of molecules.}, journal = {J Struct Biol}, volume = {166}, year = {2009}, month = {05/2009}, pages = {126-32}, abstract = {

Attempts to develop efficient classification approaches to the problem of heterogeneity in single-particle reconstruction of macromolecules require phantom data with realistic noise models. We have estimated the signal-to-noise ratios and spectral signal-to-noise ratios for three steps in the electron microscopic image formation from data obtained experimentally. An important result is that structural noise, i.e., the irreproducible component of the object prior to image formation, is substantial, and of the same order of magnitude as the reproducible signal. Based on this result, the noise modeling for testing new classification techniques can be improved.

}, keywords = {Cryoelectron Microscopy, Image Processing, Computer-Assisted}, issn = {1095-8657}, doi = {10.1016/j.jsb.2009.02.012}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19269332}, author = {Baxter, Bill and Grassucci, Robert A and Gao, Haixiao and Frank, Joachim} } @article {2112, title = {SPIDER image processing for single-particle reconstruction of biological macromolecules from electron micrographs.}, journal = {Nat Protoc}, volume = {3}, year = {2008}, month = {10/2008}, pages = {1941-74}, abstract = {

This protocol describes the reconstruction of biological molecules from the electron micrographs of single particles. Computation here is performed using the image-processing software SPIDER and can be managed using a graphical user interface, termed the SPIDER Reconstruction Engine. Two approaches are described to obtain an initial reconstruction: random-conical tilt and common lines. Once an existing model is available, reference-based alignment can be used, a procedure that can be iterated. Also described is supervised classification, a method to look for homogeneous subsets when multiple known conformations of the molecule may coexist.

}, keywords = {Image Processing, Computer-Assisted, Microscopy, Electron, Models, Molecular, Molecular Structure, Software, User-Computer Interface}, issn = {1750-2799}, doi = {10.1038/nprot.2008.156}, url = {http://www.ncbi.nlm.nih.gov/pubmed/19180078}, author = {Shaikh, Tanvir R and Gao, Haixiao and Baxter, Bill and Asturias, Francisco J and Boisset, Nicolas and Leith, ArDean and Frank, Joachim} }