Commons:Deletion requests/File:MR spin echo.ogg
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This deletion discussion is now closed. Please do not make any edits to this archive. You can read the deletion policy or ask a question at the Village pump. If the circumstances surrounding this file have changed in a notable manner, you may re-nominate this file or ask for it to be undeleted.
Incorrectly shows direction of precession switching (clockwise to counter clockwise) after inversion pulse. This does not happen. (Reason given by user:SBarnes) Zirland (talk) 22:35, 6 January 2009 (UTC)
- The whole "spinning protons" thing is actually incorrect in MR, since it's actually just a quantum effect... You might call it a "useful lie". I agree that the file can be improved (and I will be happy to share the blender sources of the video to whoever asks for them), but I believe that the file content is still informative enough to explain to a non-specialist how the whole dephasing-rephasing concept practically works, provided that a proper description is included. Maybe a change in the description would be helpful. --IngFrancesco (talk) 07:19, 7 January 2009 (UTC)
- There isn't any problem showing the classical explanation (spinning protons), that is the most common way it is explained in classes and text books and is great way to get a feel of what is happening, for the non-specialist and the specialist. I think the movie would be a great learning tool if it were correct. The problem is that it incorrectly shows the classical explanation. Before and after the 180 degree refocusing pulse the protons will precess the same direction around the magnetic field they never switch directions. This incorrectly describes the behavior and will only confuse people trying to learn how MR works. It is bad physics.
- I would love to have the blender source if you are willing to send it to me. If it is small enough to email you can send it to ay5264 -at- wayne -dot- edu SBarnes (talk) 08:50, 10 January 2009 (UTC)
Keep Even if the film is wrong, it is useful for showing a misunderstanding. (I have done some NMR, but all my experience is with continuous-wave NMR, and I am not familiar with what inversion pulses really do.) /Pieter Kuiper (talk) 11:39, 10 January 2009 (UTC)
- @SBarnes: I sent you an email with the source. I'm sorry, it's a bit big (1.6MB), but I thought that nowadays bandwidth should be cheap enough for it. :). I still feel that it's not so terribly wrong for an easy explanation, but if you could make it right that would be just great. Thanks a lot for your collaboration. --IngFrancesco (talk) 13:17, 12 January 2009 (UTC)
- Actually, I finally remember why this video makes sense (I also posted this on the talk page). The video makes sense if you are in the rotating frame reference system: then the rotation is only due to gradients and inhomogenheities, and can happen in either direction. --IngFrancesco (talk) 19:43, 16 February 2009 (UTC)
- @SBarnes: I sent you an email with the source. I'm sorry, it's a bit big (1.6MB), but I thought that nowadays bandwidth should be cheap enough for it. :). I still feel that it's not so terribly wrong for an easy explanation, but if you could make it right that would be just great. Thanks a lot for your collaboration. --IngFrancesco (talk) 13:17, 12 January 2009 (UTC)
Comment I would say that in the general case, we do not need to automatically delete 'faulty' material, just describe the fault in the description or talk page as appropriate. Maybe someone can correct it, upload a better version, or use it to illustrate common errors on the subject --Tony Wills (talk) 10:36, 20 February 2009 (UTC)
Kept. Tryphon (talk) 20:29, 24 February 2009 (UTC)