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Description: Hat of black and white neora synthetic straw. Styled as a modified breton hat, the high domed crown is of woven black synthetic straw with white woven synthetic straw accents. The wide, matching brim is set off-center to the crown, wider at front than back, and is rolled up, forming a deep trough around the crown. At the front of the hat, affixed to the visible upturned underside of the brim is a large black plastic button with a black silk tassel extending from the center. The hat is lined in black mesh, with a black grosgrain ribbon inner hatband around the inside base of the crown. Manufacturer's label sewn to inner hatband: "Beresford". United Hatters Cap and Millinery Workers International Union sewn to inner hatband, with number "798738". Accompanied by a single short hatpin with simulated black pearl head.
Date: 1955/1959
Creator: Beresford
Partner: UNT College of Visual Arts + Design

Computations of Eigenpair Subsets with the MRRR Algorithm

Description: The main advantage of inverse iteration over the QR algorithm and Divide & Conquer for the symmetric tridiagonal eigenproblem is that subsets of eigenpairs can be computed at reduced cost. The MRRR algorithm (MRRR = Multiple Relatively Robust Representations) is a clever variant of inverse iteration without the need for reorthogonalization. STEGR, the current version of MRRR in LAPACK 3.0, does not allow for subset computations. The next release of STEGR is designed to compute a (sub-)set of k eigenpairs with {Omicron}(kn) operations. Because of the special way in which eigenvectors are computed, MRRR subset computations are more complicated than when using inverse iteration. Unlike the latter, MRRR sometimes cannot ignore the unwanted part of the spectrum. We describe the problems with what we call 'false singletons'. These are eigenvalues that appear to be isolated with respect to the wanted eigenvalues but in fact belong to a tight cluster of unwanted eigenvalues. This paper analyzes these complications and ways to deal with them.
Date: June 6, 2006
Creator: Marques, Osni A.; Parlett, Beresford N. & Vomel, Christof
Partner: UNT Libraries Government Documents Department

Performance and Accuracy of LAPACK's Symmetric TridiagonalEigensolvers

Description: We compare four algorithms from the latest LAPACK 3.1 release for computing eigenpairs of a symmetric tridiagonal matrix. These include QR iteration, bisection and inverse iteration (BI), the Divide-and-Conquer method (DC), and the method of Multiple Relatively Robust Representations (MR). Our evaluation considers speed and accuracy when computing all eigenpairs, and additionally subset computations. Using a variety of carefully selected test problems, our study includes a variety of today's computer architectures. Our conclusions can be summarized as follows. (1) DC and MR are generally much faster than QR and BI on large matrices. (2) MR almost always does the fewest floating point operations, but at a lower MFlop rate than all the other algorithms. (3) The exact performance of MR and DC strongly depends on the matrix at hand. (4) DC and QR are the most accurate algorithms with observed accuracy O({radical}ne). The accuracy of BI and MR is generally O(ne). (5) MR is preferable to BI for subset computations.
Date: April 19, 2007
Creator: Demmel, Jim W.; Marques, Osni A.; Parlett, Beresford N. & Vomel,Christof
Partner: UNT Libraries Government Documents Department

Modelling H-3 and C-14 transfer to farm animals and their products

Description: The radionuclides {sup 14}C and {sup 3}H may both be released from nuclear facilities. These radionuclides differ from most others in that they are isotopes of macro-elements which form the basis of animal tissues, feed and, in the case of {sup 3}H, water. There are few published values describing the transfer of {sup 3}H and {sup 14}C from feed to animal derived food products. Approaches are described which enable the prediction of {sup 14}C and {sup 3}H transfer parameter values from readily available information on the stable H or C concentration of animal feeds, tissues and milk, water turnover rates, and feed intakes and digestibilities. It is recommended that the concentration ratio between feed and animal product activity concentrations be used as it is less variable than the transfer coefficient (ratio between radionuclide activity concentration in animal milk or tissue to the daily intake of a radionuclide).
Date: June 23, 2006
Creator: Galeriu, D; Melintescu, A; Beresford, N; Crout, N; Peterson, R & Takeda, H
Partner: UNT Libraries Government Documents Department