[3dem] 3dem Digest, Vol 142, Issue 60

Anchi Cheng acheng at nysbc.org
Thu Jun 27 08:24:21 PDT 2019


Hi, Mohamed,

Just want to answer the first part of your first question.

Even though the signal you get in super-resolution mode is real, it is very dampened by DQE
of the detector.  Let’s say you have a signal count of 100 above the background across all frequency.
If DQE at your detector pixel limit is 0.2, and at 0.8 at zero frequency.  The output of that signal to
your image becomes 100*0.2 = 20 in the former and 80 in the latter.  This only gets worse as
you go into super-resolution frequency.

Since protein or other biomolecule do not give strong signal at high resolution to start with,
my “signal across all frequency” assumption above is already false.  You can see that information
get through to your image at high frequency is much lower in reality.

If your 1Å pixel data does not give reconstruction resolution to 85% Nyquist resolution (2.35 Å resolution
for 1 Å pixel) with all the modern single-particle processing tricks, the problem is in the specimen.  The very
dampened signal in the super resolution range by unbinning your images is not going to help you.

> 1-  Will my resolution improve if I do not apply bining? 

Best,

Anchi Cheng
NYSBC


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