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The Laboratory
in the News

Genome of infectious bacterium decoded
Research teams based at Lawrence Livermore and Uppsala University in Sweden have decoded the complete genomes of separate strains of Francisella tularensis, a highly infectious human and animal pathogen. Also participating were researchers at Porton Down in the United Kingdom, the Swedish Defense Agency, the U.S. Centers for Disease Control and Prevention, and the Walter Reed Army Institute of Research.
“Comparing the genome sequences of the two strains will help us identify the genes, and their associated proteins, that cause one strain of F. tularensis to be more virulent than another,” says Livermore biologist Emilio Garcia. Knowledge of the microbe’s genomic sequence—the precise order of the nucleotide bases in its DNA—can improve scientific understanding of its fundamental physiology and metabolism. This knowledge also could help researchers develop more effective vaccines and better methods for diagnosing and treating tularemia.
Tularemia, or rabbit fever, is a rare but serious disease normally spread by insect bites and human contact with rabbits, prairie dogs, and other small and medium-size animals. The disease can be treated with antibiotics and is seldom fatal. However, it is highly infectious—as few as 10 organisms entering the body can induce a fever—and causes severe, long-lasting pneumonialike symptoms and various glandular and intestinal disorders. F. tularensis is also considered a potential bioterrorism agent.
Contact: Emilio Garcia (925) 422-8002 (garcia12@llnl.gov).

Gamma-ray bursts expel common elements
In the February 20, 2004, issue of Astrophysical Journal Letters, Jason Pruet, a Livermore astrophysicist, and Rebecca Surman and Gail McLaughlin of North Carolina State University report on their discovery that gamma-ray bursts are important sources of several common elements. Their findings are based on recent observations indicating that each gamma-ray burst expels about half a solar mass of readily visible radioactive nickel. After a few months, this radioactive nickel, which is moving at 40,000 kilometers per second, decays to iron. Their modeling calculations show that gamma-ray bursts also produce enormous quantities of such everyday elements as zinc, titanium, calcium, and scandium.
Gamma-ray bursts are rare—only a small percentage of dying stars produce them. But, says Pruet, these events may account for as much of some elements as all other stellar explosions combined.
Contact: Jason Pruet (925) 422-5850 (pruet1@llnl.gov).

Guide star sheds light on stellar origins
In a university–laboratory collaboration, a team of astrophysicists has observed for the first time that distant larger stars formed in flattened accretion disks just as the Sun was formed. Less massive stars, including the Sun, are believed to be formed in a swirling spherical cloud that collapses into a disk. Using the laser guide star adaptive-optics system created by Livermore scientists, the astronomers observed a strongly polarized, biconical nebula 10 arcseconds in diameter around the star LkHa 198 and a polarized jetlike feature in LkHa 198-IR. The star LkHa 233 featured a narrow, unpolarized dark lane similar to an optically thick circumstellar disk.
The team included scientists from Lawrence Livermore, the University of California (UC) at Berkeley, UC Santa Cruz, California Institute of Technology, the National Science Foundation’s Center for Adaptive Optics, and UC’s Lick Observatory. Results from this research were published in the February 27, 2004, issue of Science.
Contact: Claire Max (925) 422-5442 (maxce@llnl.gov).

Prototype containment vessel developed
Livermore scientists and engineers have successfully tested a prototype composite containment vessel for explosive experiments. The half-scale prototype vessel, about the size of a large medicine ball, contained an internal blast from an 8-kilogram (18-pound) soccer-ball–size sphere of C4 explosive in a test at Livermore’s Site 300. The new vessel is designed to accommodate the more stringent containment standards that are likely to be developed for future experiments with explosives, especially those involving nuclear material.
Low-density continuous aramid fibers, such as those used in bulletproof vests, make up the vessel’s outer shell, which provides the primary structural resistance against the blast forces. An aluminum liner underneath this shell provides a sealing surface and doubles as the winding mandrel for the composite filaments. This design is stronger than steel, and radiographic measurements can be taken through the vessel wall—no ports are necessary.
The team’s work is part of a joint project with Los Alamos National Laboratory to develop a full-size (2-meter-diameter) windowless firing vessel that can completely contain a cased explosive with up to 0.04 metric ton (80 pounds) of TNT equivalent.
Contact: John Pastrnak (925) 422-8403 (pastrnak@llnl.gov).

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Lawrence Livermore National Laboratory
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UCRL-52000-04-5 | May 7, 2004