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1999 ACA Meeting Buffalo, NY May
22-27
The ACA held its annual meeting in Buffalo, N.Y. this year.
Steve Ealick, the program chair, put together a fine session
schedule that required several concurrent sessions throughout
the week. The transactions symposium, "Two Decades of Synchrotron
Radiation Research", brought together speakers from several
fields to show how revolutionary synchrotron radiation has been
for crystallographic studies. Also included in the program was
the presentation of the ACA's Patterson Award to Gerard Bricogne
for his fundamental theoretical work in crystallography.
The local arrangements made by Dave Smith (local chair) and his
colleagues were excellent and show what a dedicated local committee
can accomplish in hosting such a meeting.
Workshop: Area Detector Technology
Sol Gruner opened the marathon workshop on "Area Detector
Technology: Strategies and Techniques in Obtaining and Indexing
Integrated Intensities". He discussed the basic features
and components of the CCD detector and how we as users can evaluate
the quality of our CCD equipment. Following this excellent overview,
we heard from the primary crystallographic vendors. James Pflugrath
(MSC) discussed the approaches and philosophies addressed in
d*TREK for image plate data. SAINT integration from data collected
on the SMART system was demystified by Mark Pressprich (Bruker).
Another approach to CCD data collection and processing was presented
by Rob Hooft (Nonius) and Zbyszek Otwinowski using the KappaCCD
with EVALCCD and DENZO-SMN. A final approach to data processing
employing the skewness method, implemented in the HIPPO program,
was described by Anatoliy Volkov.
Are we collecting all possible reflections in reciprocal space
or have we missed blind regions? George Sheldrick made it clear
that redundancy of data is easy to obtain using area detectors
and is necessary for such applications as absorption and beam
corrections. So how do we plan our diffraction experiment to
include all accessible regions of data with maximum redundancy?
COSMO comes to the rescue! This is an instrument independent
algorithm written by Joerg Kaercher which will predict the proper
area detector data collection strategy needed to accomplish our
goals.
Switching gears from data collection and processing considerations,
Bob Sparks and Victor Young enlightened us on how to deal with
the bewildering problem of twinned data. With the advent of the
area detector this problem has become more readily recognizable
in the data frames, a feature that was nearly lost when point
detectors were in vogue. All of us have been faced with a twin
structure, solving twins properly can be problematic. Therefore,
dealing with twins will be the subject of the ACA2000 Workshop.
Last but not least, Claude Lecomte closed the workshop with a
presentation comparing data obtained at various wavelengths using
the Nonius KappaCCD, the Bruker SMART CCD and the CAD-4, a conventional
point detector.
I would like to acknowledge the help of my fellow organizers
and all those who helped in the notebook preparation, especially
those who came to the rescue the morning of the workshop. A special
thank you to John Bollinger for his role as our computer guru.
Many thanks to all of your for your help in making the ACA'99
Workshop a complete success!
Jeanette Krause Bauer
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Workshop: Solving
Structures with SnB
SnB is a computer program that implements Shake-and-Bake, an
algorithm for solving crystal structures by ab initio, dual-space,
direct methods. ACA Workshop WK.02 served as an intensive course
devoted primarily to providing the 35 participants with an opportunity
for hands-on use of the latest version of the program. It was
held on May 22 at the Center for Computational Research (CCR),
on the campus of SUNY-Buffalo.
Following an introductory overview of direct methods by Nobel
Laureate Herbert Hauptman, Charles Weeks gave an in-depth demonstration
of the latest version of SnB, complete with examples. The participants,
who were sitting at SGI workstations, were able to follow along
with the lecture and navigate the SnB system along with the instructor.
The afternoon session began with a lecture by Robert Blessing,
who provided many useful tips concerning optimal measurement
and processing of data for direct phasing methods. Ashley Deacon
then gave an account of his personal experiences using SnB to
locate the 70 selenium sites in DP-L-glycero-D-mannoheptose-6-epimerase.
Russ Miller, Director of CCR concluded the lectures with a discussion
of computational resources for compute-intensive applications
such as SnB. He discussed the availability of an SnB server for
crystallographers lacking sufficient computing power, and he
described current efforts to integrate SnB with CONDOR/GLOBUS
software for efficient operation over networks of workstations
and PCs. A highlight of the day was the solution of a 400+ atom
A-DNA decamer using data provided by Valentina Tereshko and Martin
Egli.
The organizers are grateful to Lynne Howell, Jimmy Xu, Steve
Potter, Jason Rappleye, Cynthia Cornelius, Kerstin Hoelzer, and
Klaus Schroer who provided able assistance during the computer
sessions. A very special "Thank you" is also owed to
the entire CCR staff who set up the 20 SGI workstations. Without
their help, the workshop would not have been possible. Readers
wishing further information about SnB should visit www.hwi.buffalo.edu/SnB/.
Charles M. Weeks and Russ Miller |
