The advantages of using MAXIMUM Entropy over conventional Fourier and `difference Fourier` syntheses stem from the following facts: Ma圎nt takes the experimental error bars into account Ma圎nt incorporate Prior Knowledge (e.g., the positivity of the scattering density in some instances) Ma圎nt allows density reconstructions from incompletely phased data, as well as from overlapping Bragg reflections Ma圎nt substantially reduces truncation errors to which conventional experimental Fourier reconstructions are usually prone. It is already being applied successfully in Astronomy, Radioastronomy and Medical Imaging. It is ideally suited for tackling undetermined systems of linear questions (for which the number of variables is much larger than the number of equations). The Maximum Entropy Method (sometimes called MEM or Ma圎nt) is a general imaging technique, related to solving ill-conditioned inverse problems.
In turn, this visualization makes it possible to model and parametrize these systems, the crystal structures of which are eventually refined by Least-Squares techniques (e.g., the Rietveld method in the case of Powder Diffraction). The Fourier Transform is of central importance to Crystallography since it allows the visualization in real space of tridimensional scattering densities pertaining to physical systems from diffraction data (powder or single-crystal diffraction, using x-rays, neutrons, electrons or else). Maximum entropy reconstructions for crystallographic imaging Cristallographie et reconstruction d`images par maximum d` entropieĮnergy Technology Data Exchange (ETDEWEB)
#Yaoi gifs generator#
A web-accessible script generator provides the user interface to the system Here we describe a fully automated system for maximum entropy reconstruction that requires no user-specified parameters. A limiting factor in the adoption of maximum entropy reconstruction in NMR has been the need to specify non-intuitive parameters. A very general non-Fourier method that is capable of utilizing data collected using any of the proposed nonuniform sampling strategies is maximum entropy reconstruction. A variety of approaches that involve nonuniform sampling have been proposed, each utilizing a non-Fourier method of spectrum analysis.
#Yaoi gifs full#
In practice, however, conventional approaches to NMR that utilize the fast Fourier transform, which require data collected at uniform time intervals, result in prohibitively lengthy data collection times in order to achieve the full resolution afforded by high field magnets. Hoch, Jeffrey C.ĭevelopments in superconducting magnets, cryogenic probes, isotope labeling strategies, and sophisticated pulse sequences together have enabled the application, in principle, of high-resolution NMR spectroscopy to biomolecular systems approaching 1 megadalton. International Nuclear Information System (INIS) Automatic maximum entropy spectral reconstruction in NMR
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