<br><font size=2 face="sans-serif">Judith-</font>
<br>
<br><font size=2 face="sans-serif">I went back and looked at some of the
log files from some recent velocity experiments where I had only one cell
in the centrifuge. I basically had the centrifuge collect scans as
quickly as it could (no delay between scans). I collected interference
data as well as absorbance at A280nm, from 5.8cm to 7.3cm, with a radial
step size of 0.003cm and no replicates, speed is 42,000rpm. I was
using an 8-hole rotor.</font>
<br>
<br><font size=2 face="sans-serif">When I look at the elapsed time for
the scan, I see it vary by a few seconds, from 1:31 to 1:35. However,
when I look at the interval between the start times for adjacent scans,
it varies quite a bit (in one instance it went from 1:40 to 2:09). This
is all in the same experiment.</font>
<br>
<br><font size=2 face="sans-serif">When I look at the next experiment I
see a similar spread in elapsed time a the scan, 1:32 to 1:37. I
don't see quite the variation in the interval between start times in the
experiment, it seems they are all about 1:40 or so.</font>
<br>
<br><font size=2 face="sans-serif">I suppose this difference in start interval
could account for differing total experiment times. I think John
Philo is correct in that differing experimental times probably won't bother
any given experiment, as long as the time stamps are correct for the data.
I can't say that I have paid much attention to this before, but it
looks like the same thing happens for me as well.</font>
<br>
<br><font size=2 face="sans-serif">Interestingly, I had some communication
problems with the computer and centrifuge in between these runs that forced
me to power everything down (often helps restore communication). Upon
restarting everything, it looks like my intervals between start times
are more consistent.</font>
<br>
<br><font size=2 face="sans-serif">Good Luck, </font>
<br>
<br><font size=2 face="sans-serif">John</font>
<br>
<br>
<br>
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<td width=40%><font size=1 face="sans-serif"><b>Judith Kornblatt <judithk@alcor.concordia.ca></b>
</font>
<br><font size=1 face="sans-serif">Sent by: rasmb-bounces@rasmb.bbri.org</font>
<p><font size=1 face="sans-serif">09/25/2009 03:18 PM</font>
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<div align=right><font size=1 face="sans-serif">To</font></div>
<td><font size=1 face="sans-serif">smcbryan <smcbryan@lamar.colostate.edu></font>
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<div align=right><font size=1 face="sans-serif">cc</font></div>
<td><font size=1 face="sans-serif">rasmb@server1.bbri.org</font>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">Re: [RASMB] timing of auc runs</font></table>
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<br>
<br><tt><font size=2>In reply to the same question from two of you, yes,
the Rmin and Rmax <br>
are the same in every run - we never change them.<br>
Judith Kornblatt<br>
<br>
smcbryan wrote:<br>
> For your first two experiments at 32K, you are collecting data at
3.975<br>
> minutes per scan and 4.455 minutes per scan for the 13:15 and 14:51<br>
> experiments, respectively. Assuming you are scanning in the Abs mode
(which<br>
> the scans per unit time suggests) that is a significant difference
between<br>
> scan time, if you set the radial increment and scan limits (Rmin and
Rmax)<br>
> the same for both runs. Did you set Rmin and Rmax to the same limits?
<br>
> Our machines won't collect every scan at the set radial increment,<br>
> typically a 0.001cm experiment will average 1.0015cm radial increments.
But<br>
> that value is the same between different experiments, so your differences<br>
> are unusual. <br>
> Steve Mcbryant, PhD<br>
> Director, PPC Facility<br>
> Colorado State University<br>
><br>
><br>
><br>
><br>
> On Fri, 25 Sep 2009 13:38:01 -0400, Judith Kornblatt<br>
> <judithk@alcor.concordia.ca> wrote:<br>
> <br>
>> How consistent should the length of time for a run be? I've been
doing <br>
>> the same basic run multiple times - same speed, same number of
scans - <br>
>> and the total time for the run, as displayed on the panel of the
AUC, <br>
>> varies considerably. For example, 200 scans, 32000 rpm, the times
varied <br>
>> from 13:15 to 14:51. More recently, 200 scans at 37000, times
varied <br>
>> from about 13 hours to 14 hours. Is this variation normal?<br>
>> Judith Kornblatt<br>
>> Chemistry and Biochemistry<br>
>> Concordia University<br>
>> Montreal Quebec<br>
>><br>
>> _______________________________________________<br>
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>> <br>
><br>
><br>
> <br>
<br>
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