7,634 research outputs found
A war for principle? Shifting memories of the Union cause in Iowa, 1865-1916
No description supplie
Origins of the Human Genome Project
Dr. Cook-Deegan recounts some of the scientific and political history leading to controversy about the proper mix of private and public roles in pursuing genome research and bringing its fruits to bear, e.g., in preventing and curing disease
Temperature 1 Self-Assembly: Deterministic Assembly in 3D and Probabilistic Assembly in 2D
We investigate the power of the Wang tile self-assembly model at temperature
1, a threshold value that permits attachment between any two tiles that share
even a single bond. When restricted to deterministic assembly in the plane, no
temperature 1 assembly system has been shown to build a shape with a tile
complexity smaller than the diameter of the shape. In contrast, we show that
temperature 1 self-assembly in 3 dimensions, even when growth is restricted to
at most 1 step into the third dimension, is capable of simulating a large class
of temperature 2 systems, in turn permitting the simulation of arbitrary Turing
machines and the assembly of squares in near optimal
tile complexity. Further, we consider temperature 1 probabilistic assembly in
2D, and show that with a logarithmic scale up of tile complexity and shape
scale, the same general class of temperature systems can be simulated
with high probability, yielding Turing machine simulation and
assembly of squares with high probability. Our results show a sharp
contrast in achievable tile complexity at temperature 1 if either growth into
the third dimension or a small probability of error are permitted. Motivated by
applications in nanotechnology and molecular computing, and the plausibility of
implementing 3 dimensional self-assembly systems, our techniques may provide
the needed power of temperature 2 systems, while at the same time avoiding the
experimental challenges faced by those systems
Prairie Farms Dairy, Inc.: Economic Impact of a Dairy Cooperative [This report is now at http://purl.umn.edu/180971]
This report is now at http://purl.umn.edu/180971Dairy cooperative, fluid milk, processing, distribution, history, economic impact., Livestock Production/Industries,
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