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UltraScan Parametrically Constrained Spectrum Analysis:

This module enables you to perform parametrically constrained spectrum analysis on a chosen experimental data set. Upon completion of an analysis fit, plots available include: model lines; experiment; simulation; overlayed experiment and simulation; residuals; time-invariant noise; radially-invariant noise; 3-d model. Final outputs may include a model and computed noises.

The PCSA method is used for composition analysis of sedimentation velocity experiments. It can generate sedimentation coefficient, diffusion coefficient, frictional coefficient, f/f0 ratio, and molecular weight distributions. The distributions can be plotted as 3-dimensional plots (2 parameters from the above list against each other), with the third dimension representing the concentration of the solute found in the composition analysis. The set of all such final calculated solutes form a model which is used to generate a simulation via Lamm equations. The simulation is plotted overlaying a plot of experimental data.

The PCSA pass proceeds for a set of models each of which consists of the solute points along a curve in s,f/f0 space. The model whose RMSD of the resulting residuals (simulation-experimental difference) is the lowest forms the starting point for a second phase which uses Levenberg-Marquardt to refine the model to a final output model. The set of initial curves is specified by a s and f/f0 ranges and a direct or implied number of variations in f/f0 end-points or sigmoid par1, par2 values. The type of curve used may be any of the following.

Process:

Main Window:

The main PCSA window is shown here in the state it appears after the completion of a fit run.

PCSA Main Window, fit complete

The Curves:

After specifying the curve type and the variations to analyze, a plot of the model lines may be displayed. The sample shown here is for a Straight Line type.

PCSA Lines as specified

After analysis, the display is modified to illustrate the best model, as well as color coding of some of the other better fits. The sample here is for an Increasing Sigmoid type.

PCSA Lines after analysis

Functions:

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