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Cover of May 2002 Science and Technology Review magazine

May 2002

The Laboratory in the News

A Project with Multidimensional Purposes
Commentary by Jeff Wadsworth

Building a Virtual Telescope
The astrophysical community has a powerful new tool in Djehuty, a computer code that provides three-dimensional simulations of the evolution and structure of stars.

A New Understanding of Soft Materials
Mechanical properties of soft materials are the specialty of a unique modified atomic force microscope.

At Livermore, Audacious Physics Has Thrived for 50 Years
In their quest to thoroughly understand nuclear weapons physics, Laboratory scientists have acquired fundamental knowledge leading to an array of new applications.

Patents and Awards

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Building a Virtual Telescope
(pdf file, 4.1MB)
Lawrence Livermore astrophysicists have developed a three-dimensional code that simulates the evolution and structure of stars. The code is named after Djehuty, the Egyptian god of calculation, wisdom, and judgment. The Djehuty code was developed because the complex processes found in stars have been imperfectly modeled with one-dimensional codes. These simplified codes do not incorporate all the physics pertinent to a star’s core, where nuclear energy is produced, and do not simulate gravity in a realistic manner. Djehuty was designed to be used with massively parallel supercomputers (machines with thousands of processors working together). The code development work has taken advantage of Livermore’s expertise in computations for the National Nuclear Security Administration’s Advanced Simulation and Computing program, massively parallel computer code and algorithm development, astrophysics, high-energy-density physical data and processes, and experience in interdisciplinary coordination. The code is being applied to resolve a long-standing issue in astrophysics concerning the size of a star’s convection region, where hot plumes of gas rise and fall.

A New Understanding of Soft Materials
(pdf file, 1.5MB)
A device that combines an atomic force microscope and a nanoindenter can, for the first time, measure the mechanical properties of soft materials. These materials include certain biological tissues, polymers, and hydrated clays, an important component of soils, as well as hard materials in fluid. In conjunction with the University of California at San Francisco, Laboratory researchers are studying human teeth, most recently measuring hardness and stiffness across the junction between tooth enamel, a hard material, and dentin, a soft material. Their results indicate that this area may provide a model for the linkage of other pairs of highly dissimilar materials such as those in artificial hip replacements. Healthy and diseased human arteries have also been studied. Other researchers are applying this new apparatus to a nanoscale examination of clay crystals intercalated with water. They found that stiffness properties observed on the nanoscale—which had never before been measured—resolve longstanding questions about the role of water in seismic attenuation measurements made in the field.

At Livermore, Audacious Physics Has Thrived for 50 Years (pdf file, 3MB)
In their quest to thoroughly understand nuclear weapons physics, Laboratory scientists have acquired fundamental knowledge leading to an array of new applications.

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UCRL-52000-02-5 | May 28, 2002