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  From: Peter Schuck <>
  To  :
  Date: Wed, 21 Oct 1998 18:38:43 -0400

direct Lamm equation fitting

Dear RASMBers,

I want to share a Windows 95 software for fast direct fitting of numerical
Lamm equation solutions to analytical ultracentrifugation data from the XLA
or XLI.  The program is called 'sedfit' (apologies to Les Holladay - I
wasn't aware for some time that this name was already used, sorry for the

Different models are implemented in the program, currently for one or more
single ideal components, and for rapid monomer-dimer or monomer-trimer
systems of selfassociating species.  The known molar mass can optionally be
entered as prior knowledge. All systems are implemented with the Claverie
method and with a new moving frame of reference finite element method. 

The program also allows the algebraic calculation of time-invariant and
radial-invariant noise components, such as needed for the analysis of
interference data.  This can be used also, for example, for extracting
time-invariant noise contributions from approach-to-equilibrium scans (in
both absorbance or interference data), and subsequently correcting the
sedimentation equilibrium profiles.  It can take experimental scans as
initial distributions, which is sometimes useful in synthetic boundary
experiments.  Some models allow the global fitting of two different
experimental data sets. 

While the software is probably not entirely free of bugs, and in the
current version some features are only partially implemented, I thought it
may nevertheless be useful for many purposes.  It is planned to be
continuously updated.  

The files (with a readme) are located in in a
subdirectory called SEDFIT-SCHUCK. 

If you want to try it, please read the readme.txt and the helpfile, this is
probably essential.  If some of you find it useful, I would be happy for
feedback and suggestions for future improvement. 

Best wishes, 
Peter Schuck, PhD
Molecular Interactions Resource
Bioengineering and Physical Science Program, ORS
National Institutes of Health
Bldg. 13 Rm. 3N17
13 South Drive 
Bethesda, MD 20892 - 5766
Tel: (301) 435-1950
Fax: (301) 496-6608

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