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B14
,The advantage of this code will be that you'll always get the right answer provided you've got 2-site exchange, in-phase magnetisation and on-resonance pulses.
== Comments from the Author ==
During the implementation of model B14, Andrew Baldwin wished to raise the attention to:
'''1) Danger of errors of approximations'''.<br>
'''2) That optimal accuracy analysis should include off resonance effects'''.
Please read:
* Myint, W. & Ishima, R., Chemical exchange effects during refocusing pulses in constant-time CPMG relaxation dispersion experiments. ''J Biomol Nmr.'', 2009. ([http{{#lst://dx.doi.org/10.1007/s10858-009-9344-9 10.1007/s10858-009-9344-9]).Citations|MyintIshima09}}* Bain, A. D., Kumar Anand, C. & Nie, Z., Exact solution of the CPMG pulse sequence with phase variation down the echo train{{#lst: application to R(2) measurements. ''J. Magn. Reson.'', 2011), ([http://dx.doi.org/10.1016/j.jmr.2011.01.009 10.1016/j.jmr.2011.01.009]).Citations|Bain11}}
'''Differential relaxation effects''':<br>
Please read:
* Vallurupalli, P., Hansen, D. F., Stollar, E., Meirovitch, E. & Kay, L. E. Measurement of bond vector orientations in invisible excited states of proteins. ''Proc Natl Acad Sci USA'', 2007. ([http{{#lst://dx.doi.org/10.1073/pnas.0708296104 10.1073/pnas.0708296104]).Citations|Vallurupalli07}}* Vallurupalli, P., Hansen, D. F. & Kay, L. E., Structures of invisible, excited protein states by relaxation dispersion NMR spectroscopy. ''Proc Natl Acad Sci USA'', 2008. ([http{{#lst://dx.doi.org/10.1073/pnas.0804221105 10.1073/pnas.0804221105]) 0.1073/pnas.0804221105Citations|Vallurupalli08}}
== Equation ==
== Parameters ==
The B14 model has the parameters {$R_2^0${{:R2zero}}, $...$, $p_A${{:pA}}, $\Delta\omega${{:Deltaomega}}, $k_{ex{:kex}}$}.
== Code ==
[https://gna.org/support/?3154 Here is gna.org tracker that followed this code. It includes valuable comments.]
The library code.<br>http://svn.gna.org/viewcvs/*checkout*/ {{relax/trunk/url|path=lib/dispersion/b14.py?revision=HEAD}}
The target function. The func_B14().<br>http://svn.gna.org/viewcvs/*checkout*/ {{relax/trunk/url|path=target_functions/relax_disp.py?revision=HEAD}}
=== Example graph of test data ===
The reference for the B14 model is:
* A.J. Baldwin (2014). An exact solution for R2,eff in CPMG experiments in the case of two site chemical exchange. ''J. Magn. Reson.'', 2014. ([http{{#lst://dx.doi.org/10.1016/j.jmr.2014.02.023 10.1016/j.jmr.2014.02.023]).Citations|Baldwin14}}
== Related models ==
The [[Relaxation dispersion citation for relax|implementation of the B14 model in relax]] can be seen in the:
* [http://www.nmr-relax.com/manual/reduced_B14_2_site_CPMG_modelThe_reduced_B14_2_site_CPMG_model.html relax manual],
* [http://www.nmr-relax.com/api/3.1/lib.dispersion.b14-module.html API documentation],
* [http://www.nmr-relax.com/analyses/relaxation_dispersion.html#B14 relaxation dispersion page of the relax website].
== See also ==
[[Category:Models]][[Category:Dispersion models]][[Category:Relaxation_dispersionanalysis]]