Unique auxin regulating mechanism discovered
Contact: Ning Zheng,
The plant hormone auxin regulates many plant growth and development processes, including shoot growth, root branching, fruit ripening, tropisms, and flowering. But how such a simple molecule elicits such a variety of cellular responses has been a mystery. An important breakthrough came in 2005, when a conserved plant protein known as TIR1 (part of a protein destruction machinery system) was identified as a receptor for auxin. Now, an international group of scientists, using data collected at ALS Beamlines 5.0.2, 8.2.1, and 8.2.2, has taken a further step in unraveling the auxin mystery through a series of protein crystallographic studies that elucidate the atomic details of how auxin is sensed by and in turn activates its receptor. Their results reveal a surprising role for the plant hormone as a "molecular glue" that brings two proteins together to accelerate protein destruction. Because this protein degradation system is conserved from plants to humans, these results can be used in drug development for the treatment of human diseases such as cancer. Read more...
Publication about this research: X. Tan, L.I.A. Calderon-Villalobos, M. Sharon, C. Zheng, C.V. Robinson, M. Estelle, and N. Zheng, "Mechanism of auxin perception by the TIR1 ubiquitin ligase," Nature 446, 640 (2007).
Unexpected angular dependence of x-ray magnetic linear dichroism
Contact: Elke Arenholz,
Using spectroscopic information for magnetometry and magnetic microscopy obviously requires detailed theoretical understanding of spectral shape and magnitude of dichroism signals. A research team at ALS Beamline 4.0.2 has now shown unambiguously that, contrary to common belief, spectral shape and magnitude of x-ray magnetic linear dichroism (XMLD) are not only determined by the relative orientation of magnetic moments and x-ray polarization, but their orientation relative to the crystallographic axes must be taken into account for accurate interpretation of XMLD data. Read more...
Publication about this research: E. Arenholz, G. van der Laan, R.V. Chopdekar, and Y. Suzuki, "Angle-dependent Ni2+ x-ray magnetic linear dichroism: Interfacial coupling revisited," Phys. Rev. Lett. 98, 197201 (2007).
Storage ring rf klystron upgrade
Contacts: Ken Baptiste,
; David Robin,
The ALS is upgrading the storage ring rf klystron, which has performed well beyond its expected lifetime. Although the ALS has an identical spare, we don't know how long it will last, the technology is becoming obsolete, and there are only one or two suppliers for this class of klystron. The replacement solution is a system of four combined inductive output tube (IOT) amplifiers. This commercially available power source will support ALS operations for the next 15 to 20 years, and its higher operating efficiency should translate into reduced energy consumption and operating cost for the same output power level.
Left: Existing ALS storage ring klystron. Right: Example of the type of IOT amplifier that will replace the existing klystron.
The transmission line network for our existing two rf cavities will be modified to receive power from the combined IOT amplifiers and to add operational flexibility by providing independent phase and amplitude control of each cavity. In order to support the IOT-based amplifiers, we will upgrade the existing high-voltage power supply by replacing its final step-up/rectifier transformer. The upgrade will have lower voltage and higher current capabilities, thus will maintain existing AC input power infrastructure. We will also replace the analog rf controls with a digitally based system. These digital rf controls will provide independent phase and amplitude control of each independent cavity with greater accuracy, and dynamic range and key parameters will be programmable, providing a better feature set to meet future goals.
The upgrading process, which is being funded by the Basic Energy Sciences Division of the U.S. Department of Energy, will occur over the next three years.
ALS hosts high school interns
Contact: Center for Science and Engineering Education,
Berkeley Lab's High School Student Research Participation Program provides talented high school students with paid summer internships in science, engineering, technology, computing sciences, and related areas. This year, over 300 students applied and 30 were selected. They came not only from the San Francisco Bay Area, but from as far away as Hawaii and Pennsylvania. The students participated 40 hours a week for six weeks from June 27 through August 10. The ALS was fortunate enough to host two of these interns, Sam Bozek and John Stevick.
Sam Bozek, an Albany High School senior (as of this fall), worked on Beamline 10.0.1. His mentor, beamline scientist Alex Aguilar, took advantage of Sam's strengths in mathematics and put him to work on recalibrating the undulator. Using data he helped obtain from the beamline as well as sets of archival data, Sam performed analyses with IGOR Pro software. "The results of Sam's work will allow us to implement a new method of controlling the undulator gap that will correct for the disadvantages of the present method," said Alex. Sam's stint at the ALS has renewed his interests in math and physics. "Working at the ALS is so different from the classroom. But that's a good thing," admits Sam. "School can be dry, and finding out that I can apply what I've learned is very invigorating."
Sam Bozek (right) with his mentor, Alex Aguilar (left).
John Stevick will be a senior this fall at Berkeley High School. He was mentored by Byron Freelon and worked as part of a joint ALS/Engineering team at Beamline 7.0.1 that is designing a substrate heater for pulsed laser deposition (PLD) thin-film growth. John worked on the design and construction of the heater's temperature control box, a crucial part of the project as thin-film growth requires stable temperatures in order to control film surface chemistry. John is founder and president of the Berkeley High Engineering Club. This background stood him in good stead on his summer internship project.
John Stevick (bottom) with his mentor, Byron Freelon (top).
An abstract book of the interns' projects and more information about the High School Internship Program are available from the Center for Science and Engineering Education, 510-486-5511.
Users' Meeting: Registration and call for abstracts
Register now for the ALS Users' Meeting to be held October 4–6, 2007, at Berkeley Lab. This year, the ALS will be holding joint events with the Molecular Foundry’s User Meeting, including plenary and poster sessions, a student poster competition, exhibits of synchrotron-related equipment, and social events. See the updated meeting agenda for details. Between 500 and 600 attendees are expected for the two meetings. In addition, 12 focused workshops, several of which are jointly organized with the Molecular Foundry, will be held on Friday afternoon (October 5) and/or Saturday (October 6).
Online Abstract Submission
ALS users and staff are invited to submit abstracts for inclusion in the poster session and student poster competition. The poster sessions will be held at the conclusion of the plenary session on the first day (October 4) and will be followed by the awards banquet on the ALS patio. Brief abstracts may be submitted online on the Abstracts Web page.
Important Meeting Deadlines
Go to the ALS Users' Meeting Web site for additional details regarding the meeting program, accommodations, and online abstract submission and registration information.
Coherence 2007 Workshop draws record attendance
Contact: Janos Kirz,
Interest in coherent x-ray science is increasing rapidly, both in the areas of diffraction microscopy and x-ray photon correlation spectroscopy. The first workshop devoted to these topics was held in Berkeley in 2001. This was followed by gatherings in Cairns, Australia (2003), and Porquerolles, France (2005). The most recent workshop took place at the Asilomar Conference Center near Monterey on June 25–28, 2007. It was attended by 150 practitioners (50 more than anticipated) from all parts of the world. In addition to more than 30 talks, 70 posters were presented, showcasing progress on both the experimental and theoretical fronts. In addition to ongoing work and plans for new beamlines at third-generation light sources, new results from FLASH (the x-ray free-electron laser [FEL] in Hamburg) and from laboratory-scale x-ray lasers were discussed, as well as plans for experiments at x-ray FELs under construction on three continents.
The workshop was sponsored by the ALS, the Center for X-Ray Optics, Lawrence Livermore National Laboratory, and the Center for Biophotonics at the University of California, Davis. The poster sessions and banquet were further enlivened by refreshments generously contributed by XRADIA. The program and abstracts can be found on the conference web site.
Submit your ALS publications, invited talks, and awards by Wednesday, September 12
Contact: Ken Winters,
We have begun preparation for the DOE BES triennial review, scheduled for early 2008, and we need a complete list of ALS published information. We have developed new features in our database that will allow you to more easily submit your data. However, you are now required to log in. Please visit the ALS Publication Verification Login page, and if you have not logged into our system before, click on the link that says "Request ALS Password," and one will be sent to you.
In addition to your publications (scientific journals, conference proceedings, book chapters, completed Ph.D. theses, and patents), invited talks and awards based on research conducted at the ALS should also be entered into the ALS database. Before entering your data, please search the database. Often a colleague has already entered the information, and you can avoid duplicating the effort. Your timely response will be greatly appreciated, as it is imperative that we accurately track the publications we generate.
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!