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InTheLoop | 01.28.2008

The weekly newsletter for Berkeley Lab Computing Sciences

April 28, 2008

Seminar This Morning Will Discuss HQMC Simulation of the Hubbard Model


Ichitaro Yamazaki of the University of California, Davis will give a seminar on “High-Quality Preconditioning Techniques for the Multi-Length-Scale Hybrid Quantum Monte Carlo Simulation of the Hubbard Model” from 9:45 to 10:45 am today (Monday, January 28) in the Bldg. 50F 1647 conference room. Here is the abstract:

“The hybrid quantum Monte Carlo (HQMC) simulation of the Hubbard model is a powerful tool for studying the electron interactions that characterize the essential properties of materials, such as magnetism and superconductivity. The bottleneck of the HQMC simulation is on the repeated solutions of the underlying multi-length-scale symmetric positive definite (SPD) linear systems of equations. The traditional direct method to solve the linear system is effective for a small number of electrons, but its computational cost scales cubically with the number of electrons. Subsequently, the HQMC simulation with the direct method is limited to hundreds of electrons.

“In this talk, we present a new preconditioned iterative solver that demonstrates an optimal linear-scaling complexity of the HQMC simulation for moderately-correlated materials. This allows us to conduct simulations with thousands of electrons. The success of the iterative solver relies on a new high-quality incomplete Cholesky (IC)-based preconditioning technique that we propose. The talk will focus on the analysis and implementation of the preconditioning technique for the solution of multi-length-scale SPD systems. We will also introduce a new software package, ICPACK, to provide a uniform interface for IC-based preconditioners.”



Evaluating an Eye-Tracker for Visualization Will Be Topic on Wednesday


Chris Weigle, a post-doctoral researcher with the University of Tennessee and Oak Ridge National Lab, will give a seminar on “Evaluating an Eye-Tracker for Visualization Studies” from 11:00 am to noon on Wednesday, January 30, in the Bldg. 50F-1647 conference room. Here is the abstract:

“A commercial eye-gaze tracker can be an important tool for quantifying the benefits of new visualization techniques. The expense of such trackers has prevented many labs from studying them (it is impractical, in cost and time, for researchers to compare multiple devices), and quantitative measures from real-world use are not readily available. In this talk, I describe the visualization work from our lab, the role eye-tracking plays in evaluating our work, and the utility of commercial systems for our purposes.”



DOE Grass Roots Cybersecurity Town Hall Meeting Is Coming Up Soon


A “town hall” meeting to develop an R&D roadmap for cybersecurity to address long-term needs of the Department of Energy will be held February 11–13 at Argonne National Laboratory. Registration is open to anyone interested in the topic. A draft white paper will be developed into a report as a product of the workshop.


Mathematical Sciences Research Institute Celebrates 25 Years This Week


The Mathematical Sciences Research Institute (MSRI), located on the hill above Berkeley Lab and affiliated with UC Berkeley, is celebrating its 25th anniversary with a number of activities this week. Scientific talks will take place today through Wednesday, including a lecture by Berkeley Lab/UCB earth scientist Inez Fung. Lab Director Steve Chu will provide the keynote address at a banquet tomorrow.


Inez Fung Offers Weekly Seminar on the Physical Science of Climate Change


Inez Fung will be teaching EPS 290, Climate Change Science, on Tuesdays this semester from 2–4 pm in 401 McCone Hall. The course will read and discuss “Climate Change 2007 — The Physical Science Basis: Contribution of Working Group I to the 4th Assessment Report of the IPCC.” For the schedule, email ifung@berkeley.edu.


“Focus the Nation” Public Forum on Climate Change on Campus Thursday


“Focus the Nation: Global Warming Solutions for America” is an educational and interactive forum at the UC Berkeley campus to spotlight institutional, community, and individual action on climate change. The public is invited to attend the event on Thursday, January 31, from 8 a.m. to 4 p.m. at International House. Among the scheduled activities is a presentation by Berkeley Lab Director Steve Chu (3:30 p.m.) and remarks from Assemblyman Fabian Nunez, speaker of the California Assembly. The event is free. More than 1550 institutions nationwide are participating in the “teach-in.”


Fran Allen to Discuss the Challenge of Multi-Cores in Regents’ Lecture Thursday


Fran Allen, IBM Fellow Emerita and recipient of the 2006 ACM Turing Award, will give a presentation entitled “The Challenge of the Multi Cores: Think Sequential, Run Parallel” at 4 p.m. Thursday, January 31. The talk will be held in the Sibley Auditorium in UC Berkeley’s Bechtel Engineering Center and is sponsored by Electrical Engineering and Computer Sciences. This event is free and open to the public. Here is the abstract:

“Multi-core computers are ushering in a new era of parallelism everywhere. As more cores (and parallelism) are added, the potential performance of the system can increase at the traditional rate. But how will users and applications take advantage of all the parallelism? This talk will review some of the history of languages and compilers for high performance systems and consider opportunities for performance on multi-core systems. The talk is intended to encourage the exploration of new approaches.”


Inadvertent File Sharing Poses Potential Security Risk in Mac OS X Machines


CRD systems engineer George “Chip” Smith has discovered a potential security risk in Mac OS X Machines. Here is his description of the problem and how to fix it:

“Recently I was re-installing an Apple Mac OS X machine. After I finished and logged in to the machine, I was able to see many shared folders from other Apple systems around the immediate network area I am in. I talked with one of the users, whom I recognized in the names of the shared folders, and this person was not aware that file sharing had been enabled on his system. I helped him shut this service off.

“The Mac OS X has this capability of public file sharing built in to the operating system. At times this can be set to a ‘File Sharing On’ state, either by personal choice or by system default. While the operating system will default to sharing the user’s public folder found in the user’s home directory, it is possible to set up other directories to be shared as well. For system security reasons, it is recommended that users turn this functionality off. When this service is turned on, it will, perhaps inadvertently, make documents or files that are placed in this directory at least readable by others who may or may not have the permission of the owners to see them.

“To turn this functionality off in Mac OS X, open System Preferences, click the Sharing icon, and make sure that the File Sharing check box is unchecked. Users may also want to go into the Firewall setting (in OS X 10.5 this is in the Security icon, and in older versions it’s in the Sharing icon) and turn the firewall to its ‘On’ setting, only allowing secured services such as remote login (ssh).

“If you have any questions, please feel free to contact gdsmith@lbl.gov. I would be glad to help you. If you are outside of CRD, contact your local system administrator, bring them a snack, and I am sure they would be glad to help out.”


Lab Is Beefing Up Traffic Safety Enforcement


The Lab’s Traffic Safety Task Force has announced that there is now increased traffic safety enforcement on our site. You may have noted use of radar guns as well as the presence of UC Police, who have the authority to issue tickets with fines/points consistent with California DMV regulations. The task force is also reviewing all Lab policies and practices associated with motor vehicle, bicycle, and pedestrian safety.


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About Computing Sciences at Berkeley Lab

The Lawrence Berkeley National Laboratory (Berkeley Lab) Computing Sciences organization provides the computing and networking resources and expertise critical to advancing the Department of Energy's research missions: developing new energy sources, improving energy efficiency, developing new materials and increasing our understanding of ourselves, our world and our universe.

ESnet, the Energy Sciences Network, provides the high-bandwidth, reliable connections that link scientists at 40 DOE research sites to each other and to experimental facilities and supercomputing centers around the country. The National Energy Research Scientific Computing Center (NERSC) powers the discoveries of 6,000 scientists at national laboratories and universities, including those at Berkeley Lab's Computational Research Division (CRD). CRD conducts research and development in mathematical modeling and simulation, algorithm design, data storage, management and analysis, computer system architecture and high-performance software implementation. NERSC and ESnet are DOE Office of Science User Facilities.

Lawrence Berkeley National Laboratory addresses the world's most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab's scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the DOE’s Office of Science.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.