| Depth profile
of uncompensated spins
in an exchange-bias system
The phenomenon known as exchange bias
at the interface between a ferromagnet and an antiferromagnet
is currently a subject of intense research because of its
applications in the magnetic recording and read-head industries.
An international collaboration headed by researchers from
the University of California, San Diego, has used resonant
x-ray scattering and polarized-neutron reflectometry to determine
the depth-dependent magnetization in an exchange-biased sample.
These results provide atomic-level insights into the mechanism
of exchange bias, specifically the involvement of mutual interactions
between two kinds of uncompensated spins in the antiferromagnet
and spins in the ferromagnet. Full
story.
Publication about this research: S. Roy,
M.R. Fitzsimmons, S. Park, M. Dorn, O. Petracic, I.V. Roshchin,
Z.-P. Li, X. Batlle, R. Morales, A. Mishra, X. Zhang, K. Chesnel,
J.B. Kortright, S.K. Sinha, and I.K. Schuller, "Depth
profile of uncompensated spins in an exchange bias system,"
Phys. Rev. Lett. 95, 047201 (2005).
Contact: Sujoy Roy, sujoy@physics.ucsd.edu
First detailed
look
at RNA Dicer
Scientists have gotten their first detailed
look at the molecular structure of an enzyme that Nature has
been using for eons to help silence unwanted genetic messages.
A team of researchers with Berkeley Lab and the University
of California, Berkeley, used x-ray crystallography at ALS
Beamlines
8.2.1 and 8.2.2
to determine the crystal structure of Dicer, an enzyme that
plays a critical role in a process known as RNA interference.
The Dicer enzyme is able to snip a double-stranded form of
RNA into segments that can attach themselves to genes and
block their activity. With this crystal structure, the researchers
learned that Dicer serves as a molecular ruler, with a clamp
at one end and a cleaver at the other end a set distance away,
that produces RNA fragments of an ideal size for gene-silencing.
Full
story.
Publication about this research: I.J.
MacRae, K. Zhou, F. Li, A. Repic, A.N. Brooks, W.Z. Cande,
P.D. Adams, and J.A. Doudna, "Structural basis for double-stranded
RNA processing by Dicer," Science 311,
195 (2006).
Contact: Jennifer Doudna, doudna@berkeley.edu
Formation of
ALS Staff Safety
Committee (ALSSC)
 In
the interest of promoting a safer working environment at the
ALS and to maintain the confidence of the staff and users,
the Acting ALS Division Director has established a multidisciplinary
safety committee to review ALS environment, safety, and health
(ES&H) procedures as concerns and incidents warrant.
Specifically, the charter of the committee
is to
- Review ALS safety protocols and
recommend changes to procedures and, if necessary, organizational
changes.
- Be involved in investigating incidents,
recommending corrective actions to ALS management, and monitoring
follow-up.
- Disseminate information to ALS
staff in a timely manner on the current status of investigations,
corrective actions, and follow-up of safety incidents.
- Anticipate potential safety issues
and recommend changes; bring any unaddressed safety concerns
to the attention of ALS management.
The committee's first task is to recommend
implementation plans for the corrective actions put forward
by a subcommittee of the Berkeley Lab Radiation Safety Committee,
formed in response to recent shielding control incidents.
Specifically, the committee is to prioritize the recommendations
and decide which can be addressed quickly to make the ALS
safer.
The current avenues for raising safety
concerns remain the same: discussions with your supervisor
and in safety circles, contacting ALS ES&H personnel,
contacting a beamline coordinator, and alerting the control
room. In addition, if users or staff feel that their safety
concerns are not adequately addressed through these avenues,
they may approach the ALSSC. The members are listed below:
Ken Woolfe (chair)
Dan Colomb
Susanna Jacobson
Nicholas Kelez
Michael Martin
Howard Padmore
Corie Ralston
Art Robinson
Christoph Steier
Ben Feinberg (ex-officio)
Contact: Ken Woolfe, KDWoolfe@lbl.gov
UEC Corner: Notes
from the Users'
Executive Committee
by Clemens Heske
 The
ALS Users' Executive Committee (UEC) is a group of elected
ALS users that represents the ALS user community, both towards
ALS and Berkeley Lab management, as well as towards external
persons and groups such as members of the Department of Energy
(DOE), committees reviewing the ALS, and elected officials
in Washington and elsewhere.
Please welcome the newly elected members
of the UEC: Alessandra Lanzara, Elke Arenholz, and Hendrik
Ohldag. The other returning members of the UEC are Tony van
Buuren, Jinghua Guo, Amanda Hudson, Simon Morton, Corie Ralston,
and Ed Westbrook. I want to thank Greg Denbeaux, who was chair
of the UEC last year, for all of his efforts. I'm pleased
to have the opportunity to represent you as chair of the UEC
this year. Tony van Buuren is the vice-chair this year and
will be the chair next year.
We are here to support your needs, so
please contact me (heske@unlv.nevada.edu)
or anyone else on the UEC with any questions, comments, complaints,
or praise. You can find the contact
information of all UEC members online. In view of the
two different areas of UEC activity mentioned above, we would
be very happy to learn about your thoughts on questions like
parking, user housing, support on the experiment floor, staging
areas, etc. If there are things to improve, we would want
to know, and if things are going well, we would love to pass
the information on to the external community.
This is going to be a busy year for the
UEC. As Greg Denbeaux pointed out in the last ALSNews, budget
issues in Washington are likely to become even more important
in the near future. The Users' Associations at the light sources
across the country have formed a group to work on outreach
and education to help ensure that people understand the importance
of these facilities, and Corie Ralston is representing the
ALS UEC in this activity. Please contact her at cyralston@sff.net
if you have any questions or suggestions. Other activities
of the UEC will include the planning of the 2006 Users' Meeting,
and we will soon post the dates so that you can mark your
calendars.
Again, please don't hesitate to contact
me with any questions or concerns—I look forward to
a productive and interesting year for our Advanced Light Source!
Contact: Clemens Heske, heske@unlv.nevada.edu
Archaeology studies
using
microdiffraction at Beamline 7.3.3
One scientific discipline that shows
increasing interest in spatially resolved synchrotron diffraction
techniques is archeology. The use of x-ray microdiffraction
with either white or monochromatic beam provides structural
information on minute amounts of materials contained in ancient
artifacts, which in turn give some clues as to how these artifacts
were made.  At
Beamline
7.3.3, experiments have been carried out to identify mineral
phases in Gallo-Roman terra sigillata ceramics from the first
to third century AD. Phase distribution and grain sizes provide
information about the firing process as well as on the origin
of the raw materials. Another ongoing project is the determination
of the long-lost recipe to fabricate the Chinese Purple pigment
used to paint the terra-cotta army statues of the Qin Dynasty
(200 BC). Such studies will benefit greatly from the construction
of the new superbend Beamline
12.3.2 microdiffraction system. It is expected that operations
will be able to move from Beamline 7.3.3 in the spring of
2006, after which there will be a period of extensive commissioning
of the new system. The use of a superbend and new optics should
allow an increase in flux and strain sensitivity by a factor
of 10 and an improvement in spatial resolution to about 100
nm.
Contact: Nobumichi Tamura, NTamura@lbl.gov
Terahertz Science
and
Technology Network
There has been a recent explosion of
interest in using terahertz (THz) radiation to investigate
questions in chemistry, biology, physics, medicine, and materials
science. Simultaneously, there has been a rapid development
of a broad array of experimental tools for working with THz
radiation. In response, a collaboratory* called the THz
Science and Technology Network has been proposed. The
Network's goals are to lower barriers to experimental and
theoretical research involving THz radiation, to foster interaction
and technological innovation, and to expand the THz community.
The Network will provide necessary infrastructure
that is beyond the means of any individual investigator. A
key component of the Network is a set of nodes with research
tools and expertise that together span the current state of
the art. These nodes will provide open access to all qualified
users. A second important component is an extensive Web site
that provides thumbnail sketches of terahertz research areas,
detailed descriptions of the nodes, expert contact lists,
a virtual journal, a spectral database, calibration data,
educational materials, an interactive virtual spectrometer,
a buyer's guide, how-to manuals, press releases, a jobs clearinghouse,
conferences, and frequently asked questions. Other components
include education, outreach, development of health and calibration
standards, interface with industry, and international cooperation.
*A collaboratory is "an organizational
entity that spans distance, supports rich and recurring human
interaction oriented to a common research area, and provides
access to data sources, artifacts and tools required to accomplish
research tasks." From the National Academy of Sciences
Science of Collaboratories 2003 report.
Contact: Michael C. Martin, MCMartin@lbl.gov
Last call for
publications: Deadline
extended to Friday, January 27
The ALS is compiling a publications list
for a Division Review coming up in March. The DOE will be
looking at publications from the last three years, so please
check our online database to make sure that all of your ALS-related
publications from 2003–2005 are included. The deadline
for submitting publications has been extended to Friday, January
27, 2006.
To check the database and/or submit publications,
go to the ALS Reporting
Publications Web page and follow the instructions there.
When submitting a publication, if you don't have a certain
piece of information (e.g., page number or month published),
type "n/a" in the field. The User Services Office
will attempt to track it down. Be sure you are using an up-to-date
Web browser—Netscape 6 or 7 or Microsoft Internet Explorer
5.0 or greater. If you don't, you will lose data when you
hit the "Back" key.
 Don't
forget to include all Ph.D. and Masters theses, patents, and
book chapters in your publication submissions. Theses are
especially important as they are used to evaluate the educational
component of the national facilities. We very much appreciate
your efforts and apologize for the early deadline. It is imperative
that we accurately report the number of ALS-related publications
to the DOE and that we include them for this review. Publications
are a primary metric used by DOE in the funding process. Remember,
if it's on your CV, and all or part of the work was done at
the ALS, it should be in our database!
Contact: Barbara Phillips, BEPhillips@lbl.gov |
