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Lab’s design selected for reliable replacement warhead
The Department of Energy’s National Nuclear Security Administration (NNSA) announced that it has selected the design team from Lawrence Livermore and Sandia national laboratories to develop the reliable replacement warhead (RRW) for a portion of the nation’s sea-based nuclear deterrent. RRW is a joint NNSA–U.S. Navy program to ensure long-term confidence in a more secure, smaller, and safer nuclear weapons stockpile. NNSA and the Navy will work together to generate a detailed RRW project plan and cost estimate for developing and producing the system.
In 2006, the Nuclear Weapons Council approved the RRW concept as a feasible approach for sustaining the nation’s nuclear weapons stockpile. NNSA selected the Livermore–Sandia design because of the high confidence that it can be certified without underground nuclear testing. Several features of the design submitted by Los Alamos National Laboratory, also in partnership with Sandia, will be developed in parallel with the Livermore effort. As these features mature, they may be introduced into the warhead design as it progresses.
An important aspect of the RRW Program is its ability to exercise and maintain the critical skills of the country’s nuclear weapons design, engineering, and production personnel. An integrated team of designers and engineers led by Livermore will work with the production plants to develop the nuclear explosive component of the weapon. Sandia will develop the nonnuclear components and ensure compatibility with the Department of Defense’s Trident submarine-launched ballistic missile delivery system. The Navy will lead the overall project team.
Contact: K. Henry (Hank) O’Brien (925) 423-5017 (obrien6@llnl.gov).

Deciphering tissue-specific signatures in human genome
A collaboration led by Ivan Ovcharenko, a bioinformatics scientist in Livermore’s Computation Directorate, has translated DNA sequence data into functional signatures corresponding to specific tissues of the body. Researchers from Lawrence Berkeley National Laboratory, the Department of Energy’s Joint Genome Institute, and the University of Chicago participated in the study. Results appeared in the February 2007 issue of Genome Research.
Every tissue cell has the same code that dictates and regulates how the genome’s approximately 30,000 genes perform the organism’s myriad functions. However, much of this orchestration happens outside gene boundaries in what is known as noncoding DNA. Previously considered “junk” DNA, these regions are home to critical regulatory elements such as enhancers. Enhancers can be found in many places—inside the genes they regulate, barricaded before or after the genes they control, or located millions of nucleotide bases, or units of DNA, up or downstream from the genes they regulate.
To track down these elements, Ovcharenko’s team analyzed a massive experimental gene expression, or microarray, data set generated by the Genomics Institute of the Novartis Research Foundation. A sequence-pattern search deciphered the code of tissue-specific regulatory elements hidden in the noncoding part of the genome, and it identified the signatures for specific tissues. The team then merged three analysis factors to develop an enhanced identification score, which indicates the level of confidence that a signature’s location is accurate and that it contributes to the identified gene-expression event. This method may ultimately help scientists screen gene mutation by parsing the more cryptic elements of the genetic code.
Contact: Ivan Ovcharenko (925) 422-5035 (ovcharenko1@llnl.gov).

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UCRL-52000-07-5 | May 9, 2007