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The Laboratory
in the News

Human effects on the Great Barrier Reef
Stewart Fallon of the Laboratory’s Center for Accelerator Mass Spectrometry collaborated with researchers from Australian National University and the Australian Institute of Marine Science to study the geochemistry of coral in the Great Barrier Reef. In the February 13, 2003, issue of Nature, they published findings concluding that in the 150 years since the first Europeans settled along the Australian coast, the settlers’ land-use practices have led to a major degradation of the semiarid region and resulted in substantially increased amounts of sediment entering the Great Barrier Reef.
The researchers studied coral by measuring barium content within the coral skeleton, using a technique called laser ablation inductively coupled plasma spectrometry. Barium deposits can provide good records of how much sediment enters the reef. The barium comes loose from fine-grained particles in a low-salinity region of the estuary and is carried with a flood plume into the coral skeleton. Measurements of a 5.3-meter core from the Havannah coral reef showed a significant increase in barium beginning around 1870, about two decades after European settlers arrived in northern Queensland and began clearing land for raising sheep and cattle.
The Nature report warns that reducing sediment discharges must be a high priority if coral reefs are to survive the lethal combination of human-use effects and rapid climate change.
Contact: Stewart Fallon (925) 422-4396 (fallon4@llnl.gov).

More discoveries about neutron stars
An international group of researchers, which includes Laboratory astrophysicist Diego Torres, has shown through computer simulations that accreting neutron stars can be a source of high-energy neutrinos. The neutrinos—particles that rarely interact with other matter—are produced in amounts significant enough that they are expected to be detected by next-generation neutrino telescopes.
A neutron star is one possible end-point in the evolution of a massive star. In some binary star systems, two neutron stars are so close together that the strong gravity from one can steal gas from the other. The gas transfer onto a neutron star is accretion; it is a turbulent, shiny event.
Neutron stars have long been viewed as physics laboratories in space because they provide insights into the nature of matter and energy. Torres and his colleagues believe that astronomers will be able to use IceCube—an international high-energy neutrino observatory being built for installation in the deep ice below the South Pole—to detect neutron star neutrinos. This would mark the beginning of multiparticle astronomy, where photons in all wavelengths and neutrinos are detected at the same time.
Torres’s collaborators include scientists from Northeastern University, Instituto Argentino de Radioastronomia, and the Max Planck Institut für Kernphysik. Their research is presented in the May 20, 2003, edition of Astrophysical Journal.
Contact: Diego Torres (925) 423-0750 (torres25@llnl.gov).

Containment of a fowl disease
A partnership of researchers from Livermore, the University of California at Davis, the California Animal Health and Food Safety Laboratory, and the U.S. Department of Agriculture has developed a rapid diagnostic assay to detect Exotic Newcastle Disease (END), a virus that has been attacking poultry in California and Nevada. The new assay, which is faster and more precise, is based on DNA fingerprinting methods that Livermore perfected for use in detecting bioterrorism. It can provide test results overnight, in contrast to the 6 to 12 days previously needed to identify infected birds.
The test is based on the polymerase chain reaction, a method of multiplying DNA. Livermore scientists use powerful computers to compare the multiplied DNA sequences of a pathogen with those of close genetic kin to discover the DNA regions, or signatures, that are unique to the pathogen. Scientists can then design an assay that includes fluorescent probes that signal the presence of a signature.
Developing an assay for END was challenging because its chromosome is made of RNA rather than DNA and because close cousins of the virus were hard to find. “These are very interesting pathogens,” says Paula McCready, head of Livermore’s DNA signature team. “They mutate quickly so it’s difficult to find those regions that are unique to the virus.”
Use of the new test spared 170,000 layer hens in Riverside County from euthanasia. The assay showed that the quarantined hens did not have END but were instead infected with a nonvirulent strain.
Contact: Paula McCready (925) 422-5721 (mccready2@llnl.gov).



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UCRL-52000-03-5 | May 9, 2003