Comparing Pattern Recognition Feature Sets for Sorting Triples in the FIRST Database

Pattern recognition techniques have been used with increasing success for coping with the tremendous amounts of data being generated by automated surveys. Usually this process involves construction of training sets, the typical examples of data with known classifications. Given a feature set, along with the training set, statistical methods can be employed to generate a classifier. The classifier is then applied to process the remaining data. Feature set selection, however, is still an issue. This report presents techniques developed for accommodating data for which a substantive portion of the training set cannot be classified unambiguously, a typical case for low resolution data. Significance tests on the sort-ordered, sample-size normalized vote distribution of an ensemble of decision trees is introduced as a method of evaluating relative quality of feature sets. The technique is applied to comparing feature sets for sorting a particular radio galaxy morphology, bent-doubles, from the Faint Images of the Radio Sky at Twenty Centimeters (FIRST) database. Also examined are alternative functional forms for feature sets. Associated standard deviations provide the means to evaluate the effect of the number of folds, the number of classifiers per fold, and the sample size on the resulting classifications.Comment: 30 pages, 17 figures Accepted ApJS, March 27,200

How Mexico's Dairy Industry Has Evolved Under the NAFTA - Implications for U.S. Dairy Exporters and U.S. Investors in Mexico's Dairy-Food Businesses

This Discussion Paper shows that the demand for imported dairy products will continue to be strong in Mexico, especially after the 2001-2002 recession ends. However, Mexico's dairy markets have matured under the NAFTA. As part of the maturity, a larger number of strong domestic firms have emerged and powerful European multi-nationals have increased dairy product sales in Mexico. In addition, the expansion of U.S. exports of fluid milk, yogurt, dried whey, and lactose to Mexico will be slow in near future because U.S. market shares of imports of these products are already large. Thus, Mexico's dairy markets no longer represent "low hanging fruit" (if they ever did) for U.S. dairy exporters and direct investorsNAFTA, Maturing Mexican Dairy Markets, U.S. Dairy Exports to Mexico, Demand and Price Analysis, Food Consumption/Nutrition/Food Safety, International Development, International Relations/Trade,

Random Field XY Model in Three Dimensions: The Role of Vortices

We study vortex states in a 3d random-field XY model of up to one billion lattice spins. Starting with random spin orientations, the sample freezes into the vortex-glass state with a stretched-exponential decay of spin correlations, having short correlation length and a low susceptibility, compared to vortex-free states. In a field opposite to the initial magnetization, peculiar topological objects -- walls of spins still opposite to the field -- emerge along the hysteresis curve. On increasing the field strength, the walls develop cracks bounded by vortex loops. The loops then grow in size and eat the walls away. Applications to magnets and superconductors are discussed.Comment: 5 pages, 8 figure

Vitalogy: The Study of Life

A selection of artwork conveying Vitalogy: The Study of Lif