Hi, I would suggest a task for this and a new branch. It should only take a few days to implement. Adding it to the GUI would also be quite easy, we just need a selection box element to select between the 2 different equation types. I have already implemented the following for this type of analysis:
- the relax_fit.select_model() user function. - all of the specific code for handling the additional 'iinf' parameter. - the C code maths functions in maths_fns/relax_fit.c The only thing missing is the code in math_fns/exponential.c as well as a switch in maths_fns/relax_fit.c to select between the two different curves (there would be other ways of implementing this though). Regards, Edward On 15 June 2011 14:49, Sébastien Morin <[email protected]> wrote: > Hi, > > Thanks for your fast answer and for the explanation ! > > Indeed (!), I know some people who record R1 in this manner in my > (sometimes) very old-school lab... > > I guess we could implement this, at least for the command line version of > relax, in case some people need it... > > Cheers, > > > Séb :) > > > On 11-06-15 2:44 PM, Edward d'Auvergne wrote: >> >> Hi, >> >> The inversion recovery method whereby the signals plateau at the >> equilibrium I0 value is very old school. I don't know if anyone >> records this anymore. Maybe some chemists do. Anyway, I never added >> support for this because no one was interested or had such data. The >> new interleaved method resulting in a single exponential from I0 to >> zero is much better, in that the results are much more reliable. The >> signals affected by noise are at the end of the exponential rather >> than in the middle. And the 2 parameter fit is much more reliable for >> extracting the rate. This is all explained in the original paper, but >> I can't remember the reference off the top of my head. It should be >> referenced in the Farrow 94 paper though, which is the basic reference >> for all R1, R2, and NOE experiments nowadays. >> >> Support could easily be added to relax for this. I actually have >> coded the relax_fit analysis to support the triple parameter fit >> curve, but never implemented it. Do you know someone who has measured >> the R1 in this way? >> >> Regards, >> >> Edward >> >> >> >> On 15 June 2011 14:35, Sébastien Morin<[email protected]> wrote: >>> >>> Hi, >>> >>> Talking with some colleagues, I realized that some people record R1 data >>> with 2D versions of inversion-recovery pulse sequences, where the signal >>> starts from a negative value to a positive value, with a cross-point at ~ >>> ln >>> 2 / R1. The equation needed to fit such data is the following: >>> At = A0 (1-2e^(-R1 t)) >>> >>> In relax (and relaxgui), it is assumed that, for both R1 and R2, the user >>> records data with intensities decaying in an exponential manner (i.e. At >>> = >>> A0 e^(-R1 t) ). >>> >>> Is there a reason why most people use the exponential decay approach, >>> rather >>> than the inversion-recovery approach ? >>> >>> Should relax (and relaxgui) support the inversion-recovery approach ? >>> >>> Cheers, >>> >>> >>> Séb :) >>> >>> -- >>> Sébastien Morin, Ph.D. >>> Postdoctoral Fellow, S. Grzesiek NMR Laboratory >>> Department of Structural Biology >>> Biozentrum, Universität Basel >>> Klingelbergstrasse 70 >>> 4056 Basel >>> Switzerland >>> >>> >>> _______________________________________________ >>> relax (http://nmr-relax.com) >>> >>> This is the relax-devel mailing list >>> [email protected] >>> >>> To unsubscribe from this list, get a password >>> reminder, or change your subscription options, >>> visit the list information page at >>> https://mail.gna.org/listinfo/relax-devel >>> > > -- > Sébastien Morin, Ph.D. > Postdoctoral Fellow, S. Grzesiek NMR Laboratory > Department of Structural Biology > Biozentrum, Universität Basel > Klingelbergstrasse 70 > 4056 Basel > Switzerland > > _______________________________________________ relax (http://nmr-relax.com) This is the relax-devel mailing list [email protected] To unsubscribe from this list, get a password reminder, or change your subscription options, visit the list information page at https://mail.gna.org/listinfo/relax-devel
