mailRe: full_analysis.py


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Posted by Edward d'Auvergne on October 17, 2006 - 16:55:
Diffusion model    Round    Machine          Time      Time_for_opt/
===============    =====    =============    =======   =============
local_tm           ---      Pelican          15h00
--------------------------------------------------------------------
sphere MII         init    Pelican            0h10
                      1    Pelican           42h00     31h00
                      2    Pelican           23h00     21h00
                      3    Pelican           18h00     16h00
                      4    Pelican

prolate MIII       init    Hibou              0h20
                      1    Hibou             76h00     74h00
                      2    Hibou             44h00     39h00
                      3    Hibou

oblate MIV         init    Hibou              0h20
                      1    Hibou             76h00     75h00
                      2    Hibou             44h00     40h00
                      3    Hibou

ellipsoid MV       init    Pigeon             1h00
                      1    Pigeon            75h00     74h00
                      2    Pigeon            31h00     27h00
                      3    Pigeon            20h00     17h00
                      4    Pigeon
--------------------------------------------------------------------

Those times are quite long! They're not completely unreasonable considering you have 220 residues and data at 3 field strengths.


So, it seems the behaviour is normal with the processing times getting
shorter as the optimization proceeds... Maybe the first runs were long
because of my errors on the NOEs being too small (I think they could be
too underestimated because, with the traditional approach used in
ModelFree -- the approach from Mandel et al., 1995 -- I can select only
~20% of residues for model 1 (and almost no residues in subsequent
models) under an axially symmetric diffusion tensor...

That percentage of model m1 being selected is quite normal, maybe just a little too high because of the deliberate under-fitting of that ANOVA/hypothesis testing approach. The underestimation of the R1, R2, and NOE errors could however explain the long calculation times. The more the errors are underestimated, the more convoluted and difficult the model-free space is to optimise in. Are you experimentally determining the NOE errors by measuring the base plane noise or by running both the saturated and reference NOE spectra twice? I would value the errors of equal or greater importance than the relaxation data itself! Under or overestimation of the errors will influence both optimisation and model selection, and hence the final dynamic picture of the molecule. High quality errors are very important.


Also, the fitted values seem reasonable.

That's a good sign. Despite the amount of time this is taking, you may end up with good results, even if it does take two weeks. Unless there is something subtly wrong causing the slow down. Have you modified the 'full_analysis.py' script much? Are you sure your relaxation data is being read in correctly with the correct field strength values? How did you determine your R1 and R2 values? Were the R1 and R2 errors determined using Monte Carlo simulations?


Anyway, it seems I'll get optimized models soon and then I could look at
them and maybe exclude models 6 to 9 if I find them irrelevant... Let's
see !

I would strongly recommend in keeping those models! You have the data to fully characterise these and dropping them will induce under-fitting if you have a system which exhibits large interesting motions. It doesn't seem like this is the slow point anyway.


A question, however... Is it normal that the X2 in the opt directories
as the same value for every residue (for example in the file
ellipsoid/round_3/opt/results.bz2) ? Is it the global X2 ?

Yes. The 'opt' directory is the last part of the new protocol where the global model - the diffusion model together with all model-free models of all residues - is optimised. It is a single optimisation of the single global chi-squared value.

Edward



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