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I would simply like to echo the call for somebody, somewhere, to develop
some sort of standard.  Heck, one might even get funding for that kind of
project, if phrased the correct way!

Daniel M. Amiot II
Department of Hypertension
Case-Western Reserve University
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----- Original Message -----
From: "Alice L. Givan" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, March 16, 2004 8:51 AM
Subject: Re: Standards and Specifications.


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A word of caution.  Using standards as suggested by Bob Zucker, it is
relatively easy and very important to follow the performance of a single
confocal system over time -- to see whether an objective has degraded or a
laser is losing power etc etc.  However,  it is almost impossible to compare
confocal systems manufactured by different vendors.  We tried to do this
before the purchase of a confocal system ---- and found, as would have been
obvious if we had thought about it,  that different systems express pinhole
diameters, PMT gains, and laser intensities in different ways.  So, it is
impossible to be sure that you are comparing systems under identical
conditions.

In terms of standards ---  before I broke it,  we used to have a coverslip
etched with lines with progressively less space between them.  You could
flood the grid with a fluorescent solution,  and then look at the spaced
lines to see how close together they were when two lines merged into one
(giving a direct measure of XY resolution).  Our source of those grids is no
longer making them.  If someone knows how we could get these made,  I
suggest that we get together and commision the manufacturer of them (with an
advance order).

One other comment: why are we purchasing (and why is NIH funding the
purchase of)  $400,000 (or more)  instruments that arrive with no real
specifications about what kind of results they can be expected to produce?
I know why we purchase them (because we have no choice).  But the situation
would change rapidly if NIH (or other funding agencies) refused to fund the
purchase of instruments that were not fully guaranteed with output
specifications.

Alice

Alice L. Givan
Englert Cell Analysis Laboratory
of the Norris Cotton Cancer Center
Dartmouth Medical School
Lebanon, NH 03756 USA
tel 603-650-7661
fax 603-6540-6130
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www.dartmouth.edu/~celllab