2,863 research outputs found

    Unusual corrections to scaling in the 3-state Potts antiferromagnet on a square lattice

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    At zero temperature, the 3-state antiferromagnetic Potts model on a square lattice maps exactly onto a point of the 6-vertex model whose long-distance behavior is equivalent to that of a free scalar boson. We point out that at nonzero temperature there are two distinct types of excitation: vortices, which are relevant with renormalization-group eigenvalue 1/2; and non-vortex unsatisfied bonds, which are strictly marginal and serve only to renormalize the stiffness coefficient of the underlying free boson. Together these excitations lead to an unusual form for the corrections to scaling: for example, the correlation length diverges as \beta \equiv J/kT \to \infty according to \xi \sim A e^{2\beta} (1 + b\beta e^{-\beta} + ...), where b is a nonuniversal constant that may nevertheless be determined independently. A similar result holds for the staggered susceptibility. These results are shown to be consistent with the anomalous behavior found in the Monte Carlo simulations of Ferreira and Sokal.Comment: LaTeX, 25 pages, includes 9 figures. Version 2 includes a new footnote 3. To appear in J. Stat. Phy


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    Water quality standards and a limited water supply have dramatically restricted the expansion of the U.S. trout industry. Faced with production restrictions, producers have turned to value-added products to strengthen the economic growth of the industry. In the near future, trout steaks could surface in retail outlets as a new revenue source for the mature trout industry. A telephone survey of consumers in Chicago and Los Angeles was conducted by the University of Idaho in the spring of 1997 to determine consumer preferences for trout steaks and, ultimately, to determine the viability of this product form. Using a probit analysis, fresh trout steaks were found to be more popular than frozen trout steaks. Consumers that exhibited significantly higher preference for fresh trout steaks were Hispanic, had high school education (or less), and/or believed that trout was less expensive than other meats. Chicago respondents and individuals with an urban background tended to display a higher preference toward frozen trout steaks.Consumer/Household Economics,

    Vertical Distribution of Foraminifera in the Lower Chalk Member of the Austin Formation, Southern Dallas County, Texas

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    The Austin formation (Upper Cretaceous) in Dallas County is divisible into three members: a lower chalk, a middle marl, and an upper chalk. Because of the gentle dip of the Austin formation and the low surface relief of the area, stratigraphic sections of as much as 30 feet are rare, thus no complete surface section exists for any of the members. A composite stratigraphic section of the lower chalk member, 155 feet thick, was constructed from exposures in the upper reaches of Ten Mile Creek. Individual sections in excess of 10 feet were carefully measured and correlated by insoluble residues, in conjunction with bed thicknesses and weathering profiles, to obtain the composite section. The microfaunal content was examined at five foot intervals and points of significant lithologic change. Approximately 50 species of Foraminifera, representing 26 genera and 9 families, are present in the lower chalk member. The dominant species are Globigerina cretacea d\u27Orbigny, Globotruncana canaliculata (Reuss), G. marginata (Reuss), G. fornicata Plummer, Gumbelina striata (Ehrenberg), and Planulina sp.; cf. P. austinana Cushman. Globigerina cretacea d\u27Orbigny is the most common and persistent. All of the above are planktonic except Planulina. The only indications of limited vertical distribution within the lower chalk member were restricted occurrences of Rectogumbelina hispidula Cushman and Pleurostomella watersi Cushman. The former was observed only in a single sample taken approximately 8 feet above the Eagle Ford-Austin contact; the latter was found in samples of the uppermost 12 feet of the lower chalk section as one of the most common species; it probably, however, ranges upward into the middle and upper Austin

    Historians and John C. Calhoun: One hundred and fifty years of historiography

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    In a public career spanning forty years, South Carolinian John C. Calhoun served in a variety of offices from state legislator to United States vice president. A central antebellum figure, he presents something of an enigma. Historically, Calhoun has been identified with the South and slavery, both of which he defended vigorously. Yet his significant, if challenging, contributions to American political and constitutional thought have proven to be his most enduring legacy. In the century and a half since his death, he has been the focus of a vast number of historical works ranging from multi-volume biographies to narrowly-focused interpretive articles, many of which are passionately, if not always carefully, argued. Filled with reverence or denunciation, the extensive Calhoun historiography has become a significant story in itself. The purpose of this study is an examination of this long trail of works. The sheer enormity of studies made an inclusive approach to this historiographical analysis all but impossible, for aside from the large number of books and articles specific to Calhoun, he is also discussed in many biographies of his contemporaries, in numerous political and constitutional studies, and in countless American antebellum histories. With only rare exceptions, therefore, the fifty works herein analyzed represent only the major published works specific to Calhoun. While examined individually and in general chronological order, the studies are viewed in relation to the various schools of historical thought which have developed regarding the controversial Carolinian. Although the primary source collections and Calhoun’s own political treatises are examined in a separate chapter, all works addressing special topics are fit into the overall chronological pattern

    A role for jasmonates in the release of dormancy by cold stratification in wheat

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    Hydration at low temperatures, commonly referred to as cold stratification, is widely used for releasing dormancy and triggering germination in a wide range of species including wheat. However, the molecular mechanism that underlies its effect on germination has largely remained unknown. Our previous studies showed that methyl-jasmonate, a derivative of jasmonic acid (JA), promotes dormancy release in wheat. In this study, we found that cold-stimulated germination of dormant grains correlated with a transient increase in JA content and expression of JA biosynthesis genes in the dormant embryos after transfer to 20 (o)C. The induction of JA production was dependent on the extent of cold imbibition and precedes germination. Blocking JA biosynthesis with acetylsalicylic acid (ASA) inhibited the cold-stimulated germination in a dose-dependent manner. In addition, we have explored the relationship between JA and abscisic acid (ABA), a well-known dormancy promoter, in cold regulation of dormancy. We found an inverse relationship between JA and ABA content in dormant wheat embryos following stratification. ABA content decreased rapidly in response to stratification, and the decrease was reversed by addition of ASA. Our results indicate that the action of JA on cold-stratified grains is mediated by suppression of two key ABA biosynthesis genes, TaNCED1 and TaNCED2.This project was funded by a CSIRO Office of the Chief Executive PDF scheme

    A Discotic Disguised as a Smectic: A Hybrid Columnar Bragg Glass

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    We show that discotics, lying deep in the columnar phase, can exhibit an x-ray scattering pattern which mimics that of a somewhat unusual smectic liquid crystal. This exotic, new glassy phase of columnar liquid crystals, which we call a ``hybrid columnar Bragg glass'', can be achieved by confining a columnar liquid crystal in an anisotropic random environment of e.g., strained aerogel. Long-ranged orientational order in this phase makes {\em single domain} x-ray scattering possible, from which a wealth of information could be extracted. We give detailed quantitative predictions for the scattering pattern in addition to exponents characterizing anomalous elasticity of the system.Comment: 4 RevTeX pgs, 2 eps figures. To appear in PR