# InTheLoop | 09.19.2011

September 19, 2011

## Kathy Yelick Appointed to National Academies’ Computer Science and Telecommunications Board

Associate Laboratory Director for Computing Sciences Kathy Yelick has been appointed to the Computer Science and Telecommunications Board (CSTB) of the National Academies, which include the National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council. CSTB is composed of nationally recognized experts from across the information technology fields and complementary fields germane to the Board's interests in IT and society. Board members are appointed by the National Academies following a rigorous vetting process, and they serve staggered terms of three to five years.

CSTB was established in 1986 to provide independent advice to the federal government on technical and public policy issues relating to computing and communications. CSTB conducts studies of critical national issues that recommend actions or changes in actions by government, industry, academic researchers, and the larger nonprofit sector. CSTB also provides a neutral meeting ground for consideration of complex issues where resolution and action may be premature. It convenes invitational discussion sessions that bring together principals from the public and private sectors to share perspectives on all sides of an issue.

Yelick was previously a member of the CSTB’s Committee on Sustaining Growth in Computing Performance, which published the report The Future of Computing Performance: Game Over or Next Level? earlier this year.

## The Path to Interoperability Passes through Rio

Last week (Sept. 13–14), Inder Monga represented ESnet at the 11th Annual Global LambdaGrid Workshop, held at the Museum of Modern Art, Rio de Janeiro, Brazil. ESnet participated in a Network Services Interface (NSI) protocol “plugfest” with OSCARS, its award-winning On-Demand Secure Circuits and Advance Reservation System software, testing it against other bandwidth reservation software to determine its level of interoperability and find any issues with specifications. Monga also gave a talk titled “Networks & Power—ESnet’s Initiatives towards Green.” Read more.

## Export Control Training Session on Sept. 27

Are you in compliance with export control regulations? Do you:

• Transfer information including technical data to persons and entities outside the US?
• Make verbal, written, electronic, or visual disclosures to foreign nationals of controlled scientific and technical information either internationally or within the US?
• Travel to certain sanctioned or embargoed countries for purposes of teaching or performing research?
• Ship physical items such as scientific equipment from the US to a foreign country?

If you are a PI or administrator involved in international collaboration and projects, you need to know what it takes to be in compliance with export control regulations in order to avoid civil or criminal liability for LBNL or for an individual researcher. A training session will be held Tuesday, Sept. 27, from 9:00 to 10:30 am in the Bldg. 66 auditorium. If you have any questions, email Deb Troxell or call x7026.

## Correction: Optometrist Is On Site Every Thursday

A Lab Health Services optometrist is on site every Thursday, not every Wednesday as reported in last week’s InTheLoop. Free glasses for eye protection or assistance with computer viewing are available to all Lab employees. Eye exams are performed by appointment only. Call Health Services at x6266.

## This Week’s Computing Sciences Seminars

Laser Interferometer Gravitational Wave Observatory (LIGO) Analysis on the Open Science Grid (OSG)
Monday, Sept. 19, 9:30–10:30 am, OSF room 236
Britta Daudert, Caltech

Homology Search vs Supercomputing
Monday, Sept. 19, 2:00–3:00 pm, OSF room 236
Al Shpuntoff, AFS Informatics

Phase Transitions of AMP Algorithms in Compressed Sensing: Net/Comm/DSP Seminar
Monday, Sept. 19, 2:00–3:00 pm, 521 Cory Hall (Hogan Room), UC Berkeley
David Donoho, Stanford University

Approximate Message Passing (AMP) algorithms for compressed sensing can be generalized to employ denoising operators besides the traditional scalar shrinkers underlying the original derivation (soft thresholding, positive soft thresholding and capping). This talk gives several examples including scalar shrinkers not derivable from convex optimization — the firm shrinkage nonlinearity and the the minimax nonlinearity — and also nonscalar denoisers — block thresholding (both block soft and James-Stein), monotone regression, and total variation minimization.

We give a general formula showing precisely when such algorithms guarantee recovery of objects obeying (generalized) sparsity constraints. Let the variables $\epsilon = k/N$ and $\delta = n/N$ denote the generalized sparsity and undersampling fractions for sampling a k-generalized-sparse $N$-vector $x_0$ according to $y = Ax_0$ with entries of the $n \times N$ matrix $A$ iid standard Gaussian. The formula states that the phase transition curve $\delta = \delta(\epsilon)$ separating successful from unsuccessful reconstruction of $x_0$ by AMP is given by:

$\delta = M(\epsilon|Denoiser)$,

where $M(\epsilon|Denoiser) denotes the per-coordinate minimax mean squared error of the specified, optimally-tuned denoiser in the directly observed problem$y = x + z\$. In short, the phase transition of successful reconstruction in a noiseless undersampling problem is identical to the minimax MSE in a denoising problem.

We view this as a “precise undersampling theorem” covering a wide range of signal types and reconstructions methods.

Matrix Computations and Scientific Computing Seminar: Numerical Algorithms for the Electronic Structure Analysis
Wednesday, Sept. 21, 12:10–1:00 pm, 380 Soda Hall, UC Berkeley
Lin Lin, LBNL/CRD

Kohn-Sham density functional theory (KSDFT) is by far the most widely used electronic structure theory for condensed matter systems. The computational time of KSDFT increases as O(N^3) with respect to the number of electrons (N), which hinders its practical application to systems of large size. We have developed an accurate and efficient algorithm to solve KSDFT which is uniformly applicable to insulating and metallic systems. Our method directly uses the property that the electron density and the electron energy are fully characterized by the diagonal elements and the nearest off diagonal elements of the single particle density matrix. This property is not reflected in the current O(N^3) scaling methods. Our new method achieves O(N) scaling for quasi-1D systems, O(N^1.5) scaling for quasi-2D systems, and O(N^2) scaling for 3D bulk systems.

EECS Colloquium: Looking Around Corners: New Opportunities in Femto-Photography
Wednesday, Sept. 21, 4:00–5:00 pm, 306 Soda Hall (HP Auditorium), UC Berkeley

Can we look around corners beyond the line of sight? Our goal is to exploit the finite speed of light to improve image capture and scene understanding. New theoretical analysis coupled with emerging ultra-high-speed imaging techniques can lead to a new source of computational visual perception. We are developing the theoretical foundation for sensing and reasoning using femto-photography and transient light transport, and experimenting with scenarios in which transient reasoning exposes scene properties that are beyond the reach of traditional computer vision. (Joint work with a large team, see http://raskar.info/femto)

## Link of the Week: Where Is Everybody? Doing the Maths on Extraterrestrial Life

CRD’s Complex Systems Group Leader David Bailey and his frequent collaborator Jon Borwein are now writing a regular monthly math column for The Conversation. Their latest article, “Where Is Everybody? Doing the Maths on Extraterrestrial Life,” begins with a question posed by physicist Enrico Fermi:

Since there are likely many other technological civilizations in the Milky Way galaxy, and since in a few tens of thousands of years at most they could have explored or even colonized many distant planets, why don’t we see any evidence of even a single extraterrestrial civilization?

Mathematically speaking, Fermi seems to be right — so where are the aliens? Read more.

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.