Louis,
Yes, do it all the time.
Ian.
Dr. Ian Montgomery,
Histotechnology,
I.B.L.S. Support Unit,
G12 8QQ.
From:
Sent: 21 September 2009 14:35
To:
[hidden email]
Subject: Fixation with frozen
Paraformaldehyde
Bonjour à tous,
Can
Paraformaldehyde 2-4% can be frozen for future use without lost of fixation's
efficiency?
Thanks
for your help?
Louis
|
Francisco Henriques
<[hidden email]>@LISTS.UMN.EDU 2009-09-11 11:42
|
|
Dear
all,
First of all, hello everyone.
I am new to the mailling list and the microscopy
world.
I'm a portughese student and am currently doing my
master thesis at the
Instituto Gulbenkian de Ciência under the guidance
of Nuno Moreno.
We are trying to measure the light capturing
efficiency of a confocal
microscope but aren't sure of the methodology and
were hoping you could shed
some light on it.
The efficiency we want to measure is the fraction
of photons emitted from a
light source that is detected in the final image,
being: efficiency= np/ne,
where np is the number of detected photons and ne
is the photons emitted by a
calibrated light source(LED).
To calculate np we assumed there was no
amplification noise, and used the mean
of the image M and it's variance V.
M=np*g and V=np*g^2.
Being g the average pixel intensity resulting from
the detection of one photon,
which is proportional to the gain of the PMT and
subsequent elecronics. And np
the average detected photons per pixel.
Our doubt is in the calculation of ne.
Is each pixel a representation of all the light
that reaches the lens during the
pixel dwell time?
If so, ne should be the number of photons that
reach the lens during the dwell
time.
If not, if each pixel represents only a portion of
the light that reaches the
lens during the dwell time, than ne should be a
fraction of the number of
photons that reach the lens during the dwell time.
I have searched, but I am unable to find any kind
of tutorial to help me
understand this concept. If somebody could point
me in the direction of a good
source to understand how this should be done, I
would be very grateful.
Many thanks
Francisco Henriques
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