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Building a Virtual Telescope
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 stars
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 Livermores expertise
in computations for the National Nuclear Security Administrations
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 stars convection region, where hot plumes
of gas rise and fall.
A New Understanding of Soft Materials
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 nanoscalewhich
had never before been measuredresolve 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
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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May 28, 2002