The optimization of large trusses often leads to a nearly optimal solution, rather than a truly optimal design. In fact, the problem space for truss optimization grows exponentially with the size of the truss. Using the method of problem reduction, this paper demonstrates that truss optimization is in the set of NP-complete problems. Hence, the only practical techniques for solving the truss pr...

Among various DNA computing algorithms, it is very common to create an initial data pool that covers correct and incorrect answers at first place followed by a series of selection process to destroy the incorrect ones. The surviving DNA sequences are read as the solutions to the problem. However, algorithms based on such a brute force search will be limited to the problem size. That is, as the ...

One of our goals is to understand the mechanisms that deposit mineral within collagen fibrils, and as a first step we recently determined the size exclusion characteristics of the fibril. This study revealed that apatite crystals up to 12 unit cells in size can access the water within the fibril, whereas molecules larger than a 40-kDa protein are excluded. Based on these observations, we propos...

Led by PET A n estimated 1,129,900 clinical PET studies were performed in the United States in 2005, according to a report released in August by IMV Medical Information Division, a market research and consulting firm in Des Plains, IL. These studies were performed in 1,725 hospital and nonhospital sites, using dedicated PET/CT or PET units, mobile units, or nuclear medicine cameras with coincid...

SOCIETIES THRIVE AS ECONOMIC FREEDOM GROWS F more than two decades, the Index of Economic Freedom has documented the vital role of economic freedom in promoting human progress. People living in nations with higher degrees of economic freedom prosper because their governments rely on systems of free markets to regulate economic activity. At their best, operating without interference, free market...

In this study, we present a new tabu search algorithm for the quadratic assignment problem (QAP) that utilizes an embedded neighborhood construction called an ejection chain. Our ejection chain approach provides a combinatorial leverage effect, where the size of the neighborhood grows multiplicatively while the effort of finding a best move in the neighborhood grows only additively. Our results...

Uncertainty quantification schemes based on stochastic Galerkin projections, with global or local basis functions, and also stochastic collocation methods in their conventional form, suffer from the so called curse of dimensionality: the associated computational cost grows exponentially as a function of the number of random variables defining the underlying probability space of the problem. In ...

Small is big. Although " nanotechnology " has been an academic and media buzz word for several years, the federal government and private investors are now backing a host of initiatives with huge sums. In fiscal year 2005, federal agencies are slated to spend more than $1 billion on nanotechnology—defined as science and engineering at the scale of one billionth of a meter, or about the width of ...

This paper discusses an iterative multiuser receiver for codedivision multiple access (CDMA) with forward error control coding. The receiver is derived from the maximum aposteriori (MAP) criterion for the joint received signal. A major drawback of the MAP receiver is its heavy computational cost that grows exponentially with the number of users. An alternative solution is proposed here based on...