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SVEDBERG

Note: the absence of SVEDBERG program updates for several years does not mean program development has halted. This simply reflects the fact that no bugs have been reported since the last update! A major revision is in progress, including a user interface similar to that in DCDT+ version 2.

What is SVEDBERG?

SVEDBERG is a Windows program for analysis of sedimentation velocity data. It fits directly to either absorbance or interference scans to derive the sedimentation and diffusion coefficients (or, if you prefer, sedimentation coefficient and molecular mass) for up to 4 independent species.

It is designed to be quick and easy to use, yet to give robust results. Many users find that they can finish the analysis of one sample before the centrifuge rotor has stopped spinning! It has a comprehensive, context-sensitive Help system and on-line manual to guide the user. It is being used in over 50 labs around the world (partial list here). It has been used to analyze data for at least 88 publications.

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How is it different than other velocity analysis programs?

SVEDBERG is particular good at accurate quantitative results and at resolving properties of minor species present in low amounts (e.g. 5% of a dimer).

SVEDBERG uses "intelligent file loading" to make it easy to load a series of scan files for analysis, and allows you to quickly see the properties of each scan or remove unwanted scans without starting over.

For multi-species fits SVEDBERG also allows the user to constrain the properties of the species with respect to one another, forcing the constrained species to have hydrodynamic properties which are in ratios appropriate for small oligomers. These constraints can significantly enhance the ability to resolve minor species (and also the accuracy of the results for the major species).

SVEDBERG also helps you to document and reproduce your analyses by printing complete reports listing exactly what data were fitted and all parameters which affect the results, and by saving all data and parameters in a single binary data file so you can instantly reload an entire analysis.

How Does the Current Version Differ from the Old Freeware Version (5.01)?

SVEDBERG now has a comprehensive, context-sensitive Help file and on-line manual with over 200 topics, step-by-step tutorials, tips, "how-to" guides, and images of all forms.

SVEDBERG now works well with interference data:

	a new "delta-c" fitting mode that eliminates systematic baseline noise for interference (or absorbance) data
	compensation for integer fringe shifts and an optional matching region to take care of small scan-to-scan vertical displacements of the fringes

sedimentation coefficients can optionally be internally converted to s_20,w values

improved Claverie finite-element simulator with real-time graph for "what-if" simulations

up to 100 scan files can be generated, with or without random noise, can be generated and optionally saved to disk as normal scan files

improved ease-of-use

	the automatic loading of a sequence of data files can be set to terminate after a specific number of scans
	the setting of radial ranges of data to be included in the fit was simplified
	a Microsoft-style recently-used file list for quickly retrieving saved fits
	saved fits (*.fit files) are now associated by Windows® with the program so they can be restored by double-clicking on the file name
	a Printer Setup command was added to the File menu for easier selection of the printer to be used for fit reports and graphs
	a new program default can optionally reduce the size of the graphs window to leave room for the Windows® 95/98 Taskbar
	improved ease and accuracy of setting of meniscus positions

improved reports of fitting results

printed reports now include the best-fit diffusion coefficient(s) when M is being used as a fitting parameter, or the apparent M values when D is being used as a fitting parameter

the molecular mass calculator form will now also calculate D values for a given mass and s value

a new graph type is available for interference scans showing all the scan files after correction for integer fringe shifts and after Y matching, if used

a new 'species' graph shows the contributions of each individual species to the signal for multi-species analyses

all graphs containing more than one data set can now be converted to a 'movie' mode where each one is seen in sequence, or the data set displayed can be manually controlled via a scroll bar

improved exporting of data via the Clipboard for use in other programs

improved sizing of forms and fonts when running at a video resolution of 640 x 480 (but 800 x 600 or higher is still recommended, see System Requirements below)

improved appearance of all forms

How does SVEDBERG differ from the multi-component models in Peter Schuck's SEDFIT?

SEDFIT is an excellent program with many strengths. It's 'non-interacting discrete species' model is essentially equivalent to the model used in SVEDBERG, except it derives the theoretical fits via finite-element numerical methods rather than approximate analytical functions. Both approaches can give an accuracy of 1% or better for hydrodynamic properties, i.e. more than sufficient for any real experiment. The analytical function approach used in SVEDBERG is faster to compute and allows the use of a Gauss-Newton fitting algorithm that converges more rapidly (especially when many components are present) than the simplex algorithm used in SEDFIT. Thus overall SVEDBERG is generally faster and easier to use, and can successfully converge on multi-species fits in situations where SEDFIT fails to converge on a solution.

Perhaps more significantly, SVEDBERG always gives error estimates for all the fitted parameters, and can derive robust confidence limits for all parameters when desired, whereas SEDFIT can only derive confidence limits for s or M for a single component and through a lengthy procedure.

Another key difference is that SVEDBERG provides printed reports that completely document the analysis and saves all data and parameters into a single file that can be quickly restored. SEDFIT has no reporting capability and a very limited ability to restore previous analyses, making it difficult to reproduce or document what you have done.

Some other advantages of SVEDBERG over SEDFIT:

	for multi-species fits the relative masses or sedimentation coefficients can be constrained to values appropriate for a series of oligomers
	true context-sensitive, indexed and searchable HELP file
	accurate, easy, and reproducible setting of meniscus position and data fitting limits
	superior graphs that can be printed, exported or saved to disk, with full graph scaling and customization capabilities
	handles conversions of raw s and D values to s_20,w and D_20,w
	superior ease-of-use

Some advantages of SEDFIT over SVEDBERG:

	models for associating systems and non-ideal sedimentation
	can use data near base of cell where solutes accumulate
	works with very low mass species such as peptides
	does flotation analysis as well as sedimentation

What does SVEDBERG cost (and why is it no longer freeware)?

To continue using this program after the 30-day trial period, or to publish results of analyses run during the trial period, you must purchase a software license for $400 (discounted to $250 for academic and non-profit institutions).

Yes, SVEDBERG used to be freeware, but since 1998 there has been no source of funds to pay for user support or program development and distribution other than you, the user. If you don't think this program is worth paying for, simply don't use it. Remember, too, that most "free" programs in this field were actually paid for by your taxes, and thus you paid for them whether you wanted to or not.

This is a "site" license and users may run the program on multiple computers at a single site. For academic/non-profit licenses "site" means a single laboratory or a single Facility. Analytical centrifuges housed in more than one department or building of a university, or under the control of independent principal investigators, by definition represent different 'sites' and therefore each of those sites must purchase its own license. For users in industry a "site" is by definition a single analytical centrifuge, and companies are expected to buy a license for each centrifuge.

Registered users will receive support for their questions, free updates, and quick fixes for any bugs they find. To date all bugs have been fixed in 1 month or less (and often in less than a week). Don't you wish you could say the same about the other software you use?

Ordering information

There is no difference between the "trial" and "registered" versions of the program---registered users are supplied a serial number which removes the 30-day restriction and also allows the start-up "splash screen" to be bypassed.

Detailed information about payment by check or purchase order, and placing credit card orders by phone or the Internet, is contained here and in the program Help file.

The program is only available electronically by downloading---it cannot be supplied by diskette or CD-ROM.

System Requirements

SVEDBERG will run under Windows^® 3.1, 95^®, 98^®, NT^®, 2000^®, or XP^® (but please note that future updates may no longer support Windows 3.1). It does not run under Asian-language versions of Windows 95 or 98. It is also reported not to run under Windows^® emulation on MacIntosh and IMac systems, and operation under such environments is neither supported nor guaranteed.

Although SVEDBERG will run correctly at a 640x480 (VGA) video resolution, a resolution of 800x600 or higher is highly recommended.

The program requires approximately 2.4 MBytes of disk space.

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