[3dem] help on FSC plot

[Sacha De Carlo]

Hi,

there are a number of things I can think of that produce this effect. If my memory doesn't betray me, a too tight window around the particles (when you boxed them) may produce this, or if you calculated an FSC on filtered volumes, or the CTF correction protocol you used (if any) is creating artifacts such that the noise is getting correlated at (and after) the frequency cut-off corresponding to your 0.3 unit.

Hope this helps.

Dig in the literature, as I am sure as hell somebody has reported these problems already.
Good luck!

Sacha




================================================
Sacha De Carlo, Assistant Professor
Chemistry Department, Marshak Science Building &
New York Structural Biology Center
The City College of New York
Convent Ave & 138th Street
New York, NY 10031
(212) 650-6070
e-mail: sdecarlo at ccny.cuny.edu
URL: http://www.planetesacha.com
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--- On Thu, 1/20/11, XIM9 at pitt.edu <XIM9 at pitt.edu> wrote:

From: XIM9 at pitt.edu <XIM9 at pitt.edu>
Subject: [3dem] help on FSC plot
To: 3dem at ncmir.ucsd.edu
Date: Thursday, January 20, 2011, 12:11 PM

Dear all,

I determined the resolution with the FSC plot. However, the FSC values
didn't drop down to the bottom, but stop at FSC=0.3, then increased. Does
anybody know why and how to fix it?

Two 3D volumes for FSC calculation were computed from two randomly
selected half of data set using BP 32F, SPIDER program.


Thanks,
Xin Meng


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