[RASMB] Spikes in data

[John Philo]

Mitra,

I'm not sure I understand exactly what this 'spike' looks like, but
sometimes dirt on the slit assembly will produce noise in certain scans and
not others, and it tends to move around. Another effect that might cause
something like that is bending of the light beam due to a strong gradient of
some molecule that doesn't absorb at that wavelength (the refractive index
gradient makes the light miss the opening in the slit assembly). This latter
issue has been discussed a number of times on RASMB previously, I think most
recently under a discussion of 'Schlieren effects' or something like that,
so check the archives.

John

-----Original Message-----
From: rasmb-bounces at rasmb.bbri.org [mailto:rasmb-bounces at rasmb.bbri.org] On
Behalf Of mitrana at mail.utexas.edu
Sent: Thursday, August 30, 2007 11:41 AM
To: RASMB
Subject: [RASMB] Spikes in data


Hi All
I recently saw a phenomenon I had previously not come across. During
sedimentation equilibrium, a spike appears on the scan and subsequently
moves towards the cell bottom in subsequent scans. It seems to be
independent of the cell position - saw it in cell # 3 last week and cell # 1
this week. Any ideas as to what might have caused this?

Mitra
-- 
Mitra S. Rana
Graduate Student
Institute for Cellular and Molecular Biology
2500 Speedway, UT-Austin
Austin, TX-78712 _______________________________________________
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