406 research outputs found

    Correlates of Northern Bobwhite Distribution and Abundance with Land-Use Characteristics in Kansas

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    County-level agricultural statistics were correlated with Rural Mail Carrier Survey reports and Breeding Bird Survey data for northern bobwhite (Colinus virginianus) in Kansas. Results indicate statewide analysis is feasible when temporally congruent data exist for both agricultural land-use characteristics and bobwhite distribution and abundance. Interpretations of these results can be useful in state or regional analysis and in the development of habitat management strategies for bobwhite. The Multiple Response Permutation Procedure identified 16 land-use variables, 3 soil variables, and 1 spatial variable that were significantly different in counties where bobwhite were present from counties where they were absent. Sixteen land-use variables, 5 soil variables, and 3 spatial variables distinguished between counties where bobwhite abundance was classified as high or low. Spearman\u27s rank correlation identified 8 soil variables, 14 land-use variables, and 3 spatial variables that were significantly correlated with bobwhite abundance. Least absolute deviation regression analysis revealed 4 land-use variables that were significantly correlated (Agreement= 0.48, P = 0.0001) with bobwhite abundance

    On cap sets and the group-theoretic approach to matrix multiplication

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    In 2003, Cohn and Umans described a framework for proving upper bounds on the exponent ω of matrix multiplication by reducing matrix multiplication to group algebra multiplication, and in 2005 Cohn, Kleinberg, Szegedy, and Umans proposed specific conjectures for how to obtain ω = 2. In this paper we rule out obtaining ω = 2 in this framework from abelian groups of bounded exponent. To do this we bound the size of tricolored sum-free sets in such groups, extending the breakthrough results of Croot, Lev, Pach, Ellenberg, and Gijswijt on cap sets. As a byproduct of our proof, we show that a variant of tensor rank due to Tao gives a quantitative understanding of the notion of unstable tensor from geometric invariant theory

    Discovery of a ~1 Hz quasi-periodic oscillation in the low-mass X-ray binary 4U 1746-37

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    We have discovered a ~1 Hz quasi-periodic oscillation (QPO) in the persistent X-ray emission and during type I X-ray bursts of the globular cluster source, dipper and low-mass X-ray binary (LMXB) 4U 1746-37. The QPO properties resemble those of QPOs found recently in the LMXB dippers 4U 1323-62, and EXO 0748-676, which makes 4U 1746-37 the third source known to exhibit this type of QPOs. We present evidence for X-ray spectral changes in this source similar to those observed in LMXBs referred to as atoll sources. We detect two states, a low intensity and spectrally hard state, and a higher intensity and spectrally soft state. This may explain the different spectral characteristics reported for 4U 1746-37 earlier. The high intensity state resembles the banana branch state of atoll sources. The QPOs are only seen in the low intensity state, and are absent when the source is in the banana branch. This strongly suggests that either the accretion disk or an extended central source change shape between the low intensity state and the banana branch. Twelve bursts were detected, of which 5 took place while the source was on the banana branch and 7 when the source was in the low intensity state. The bursts occurring on the banana branch had an e-folding time ~3 times longer than those which occurred in the low intensity state. Whereas previously detected dips showed only a decrease in count rate of ~15%, we found in one observation a dip in which the count rate dropped from ~200 counts per second to ~20 counts per second. This dip lasted only ~250 seconds, during which clear spectral hardening occured. This is the first time strong evidence for spectral changes during a dip are reported for this source.Comment: 17 pages, accepted for publication in Ap

    The Grizzly, November 30, 1999

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    Bears Take a Beating Against Rowan in the NCAA Division III Tournament: Final Score 55-0 • Judicial Board Finds Two Students Guilty • Judicial Board: How the System Works • S.T.A.R.: Providing Help for Victims of Sexual Assaults • Ursinus\u27 Political Link to the Collegeville Community: Dr. Goetz • Experiencing the Trappe Tavern • Student Says Sayonara to UC and Opts for Off-Campus Experience • Letters to the Editors: Violence on Campus; The White Agenda; A Case of Race • Bears Gain First Victory in NCAA Division III Playoffs • Rowan Overpowers Ursinus in Second Round of Playoffs • Fan-Vans Travel to Bridgewater, Mass. • Ursinus Swimming Fights Hard Against Gettysburghttps://digitalcommons.ursinus.edu/grizzlynews/1453/thumbnail.jp
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