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Realtime Functions

Data | Realtime Update of Files

Data | Stop Realtime Update

The realtime functions allow a quick analysis of the available data while the centrifuge is still running and acquiring data. 

Please note that these functions are still in an experimental stage, and no guarantee can be given that running sedfit in this mode does not interfere with the data acquisition!

My first experiments did not show any detrimental effects on the data acquisition or interference with the XLA program, even when sedfit was brought to a crash.  However, these things may be dependent on the particular computer running the XLA, and I have no experience with this on other machines, yet.

The basic idea is the following:  After starting the scans of a velocity run, one can start Sedfit and do an analysis of the first few scans (2 minimum).  After switching to the realtime mode, sedfit then automatically incorporates any new files into the analysis, and updates the results and the display of the available data.


The anticipated advantages: 

* one can quickly assess if the material is OK, and perhaps stop the run if it is not, and/or if the basic question of the experiment can already be answered by the available data.

* the display of the data is continuously updated and the calculated time-invariant noise is removed.  This allows quick visual assessment of the sedimentation boundaries also for the interference optical data.

* it can be a lot of fun to see more clearly how the run is progressing with the realtime analysis


There are clear disadvantages:

* dependent on the speed and memory of the computer, sedfit could potentially slow down the data acquisition. (I have not noticed this on our machine, though, even when running multiple copies of Sedfit.)

* worse, sedfit could crash, and in the process potentially interfere with the data acquisition, resulting possibly in the loss of the run.  (Have not seen this, so far.)

* even if sedfit doesn't interfere, the resulting analyses are based on a limited number of data sets, which may not reflect well the final analysis when all the data of the complete run are considered. (Sometimes, the calculated distributions from very early data do look strange.)

* collecting the maximum number of sedimentation velocity scans until everything has disappeared is always best.


This is how it works in practice:

1) load a few scans (minimum two), locate the meniscus and bottom and the fitting limits, as usual.

2) select an analysis -- this can be multiple species, c(s), or ls-g*(s) (perhaps even van Holde-Weischet, I haven't tried this yet) and execute like usual one analysis with the Run or the Fit command.

3) Switch the Realtime Update of Files on.  In order to keep the computation time down, Sedfit calculates only with a certain maximum number of files, the default is 20.  As soon as more than 20 scans are available, Sedfit will automatically choose every second, third, etc., scan such that the total number of files remains lower than the predefined limit.  In this way, despite reducing the number of scans, the complete time range of available scans will be utilized.

4) Clicking on the Realtime Update of Files menu initiates a re-analysis of the scans at that time.  From now on, Sedfit sets a timer and will look every 20 seconds into the data directory to find out if there are any new scans showing up.  If there are, it will beep and reload the data including the new ones, and reanalyze the available data using the current model.  If there are no new data, Sedfit will only update the screen. 

Sedfit makes a special operation for the distribution models (c(s) or ls-g*(s)) - if it turns out that the s-range was too small or too large, Sedfit will readjust the s-max value and recalculate the distribution every 20 sec, irrespective if there are new data or not.  This feature can be turned on by answering 'yes' to 'auto adjust distribution range?'. 

5) The realtime mode can be stopped by pressing any key, or by using the menu function. (This can be done, for example, in order to change manually the analysis model.)