9,665 research outputs found

    \u3ci\u3eLycaeides Melissa Samuelis\u3c/i\u3e (Lepidoptera: Lycaenidae) Response to an Aggregation of \u3ci\u3eLytta Sayi\u3c/i\u3e (Coleoptera: Meloidae) on \u3ci\u3eLupinus Perennis\u3c/i\u3e (Fabaceae

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    Lycaeides melissa samuelis Nabokov, frequently called the Karner blue butterfly, is a Federally endangered species found in savanna/barren type ecosystems of New England and the Great Lakes region of North America. We observed sporadic and localized feeding aggregations of Lytta sayi LeConte (Coleoptera: Meloidae) on Lupinus perennis L. (Fabaceae) occupied by L. m. samuelis during the summers of 2000-2004, in Eau Claire County, Wisconsin. In 2004, we quantified the phenology and behavior of an aggregation (\u3e 900 beetles) within a 1,020 m2 stand of lupine and measured its effect upon adult L. m. samuelis behavior. The L. sayi aggregation formed and dispersed within 11 days with three beetles observed on day one and a maximum of 951 beetles on day seven. By the eighth day of the aggregation, the beetles had consumed 100% of the lupine flowers, 2% of lupine seeds and no lupine leaves. In comparisons of L. m. samuelis activity before and during the beetle aggregation, L. m. samuelis males spent significantly less time perching on Potentilla simplex Michaux (Rosaceae) and more time flying during the beetle aggregation. L. m. samuelis females spent significantly less time under lupine leaves during the beetle aggregation. Distribution of L. m. samuelis larval feeding damage suggests adult females avoided ovipositing in areas containing large numbers of beetles

    Permanental Ideals

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    The principal result is a primary decomposition of ideals generated by the (2x2)-subpermanents of a generic matrix. These permanental ideals almost always have embedded components and their minimal primes are of three distinct heights. Thus the permanental ideals are almost never Cohen-Macaulay, in contrast with determinantal ideals.Comment: 13 page

    Radiation counting technique allows density measurement of metals in high-pressure/ high-temperature environment

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    Radioactive tracers induced by neutron irradiation provide a gamma ray flux proportional to the density of a metal, allowing density measurement of these metals in extreme high-temperature and high-pressure environments. This concept is applicable to most metals, as well as other substances

    Dispersion Relations for Bernstein Waves in a Relativistic Pair Plasma

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    A fully relativistic treatment of Bernstein waves in an electron-positron pair plasma has remained too formidable a task owing to the very complex nature of the problem. In this article, we perform contour integration of the dielectric response function and numerically compute the dispersion curves for a uniform, magnetized, relativistic electron-positron pair plasma. The behavior of the dispersion solution for several cases with different plasma temperatures is highlighted. In particular, we find two wave modes that exist only for large wavelengths and frequencies similar to the cyclotron frequency in a moderately relativistic pair plasma. The results presented here have important implications for the study of those objects where a hot magnetized electron-positron plasma plays a fundamental role in generating the observed radiation.Comment: 8 pages, 8 figures, Accepted for publication by Phys. Rev. E with minor change

    Inflation Assisted by Heterotic Axions

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    We explore the possibility of obtaining inflation in weakly coupled heterotic string theory, where the model dependent axions are responsible for driving inflation. This model can be considered as a certain extrapolation of m2ϕ2m^{2}\phi^{2}-inflation, and is an attempt to explicitly realize the so called N-flation proposal in string theory. The instanton generated potential for the axions essentially has two parameters; a natural mass scale MM and the string coupling gsg_{s}. For isotropic compactifications leading to of order O(104)\mathcal{O} (10^4) axions in the four dimensional spectrum we find that with (M,gs)(MGUT,0.5)(M, g_{s})\simeq(M_{GUT}, 0.5) the observed temperature fluctuations in the CMB are correctly reproduced. We assume an initially random distribution for the vevs of the axions. The spectral index, nsn_{s}, is generically more red than for m2ϕ2m^{2}\phi^{2}-inflation. The greater the vevs, the more red the spectral index becomes. Allowing for a wide range of vevs 55 ee-foldings from the end of inflation, we find 0.946ns0.9620.946\lesssim n_{s} \lesssim 0.962. The tensor-to-scalar ratio, rr, is more sensitive to the vevs, but typically smaller than in m2ϕ2m^{2}\phi^{2}-inflation. Furthermore, in the regime where the leading order theory is valid, rr is bounded by r<0.10r < 0.10. The spectral index and the tensor-to-scalar ratio are correlated. For example, ns0.951n_{s}\simeq 0.951 corresponds to r0.036r\simeq 0.036.Comment: 1+21 pages, 2 figures, v2: Typos corrected, v3: Typos, very minor corrections, reference added, to appear in JCA

    Weak Convergence of the Scaled Median of Independent Brownian Motions

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    We consider the median of n independent Brownian motions, and show that this process, when properly scaled, converges weakly to a centered Gaussian process. The chief difficulty is establishing tightness, which is proved through direct estimates on the increments of the median process. An explicit formula is given for the covariance function of the limit process. The limit process is also shown to be Holder continuous with exponent gamma for all gamma < 1/4.Comment: to appear in Probability Theory and Related Field

    Positron-neutrino correlations in 32Ar and 33Ar Decays: Probes of Scalar weak currents and nuclear isospin mixing

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    The positron-neutrino correlation in the 0^+ \to 0^+ \beta decay of ^{32}Ar was measured at ISOLDE by analyzing the effect of lepton recoil on the shape of the narrow proton group following the superallowed decay. Our result is consistent with the Standard Model prediction; for vanishing Fierz interference we find a=0.9989 \pm 0.0052 \pm 0.0036. Our result leads to improved constraints on scalar weak interactions. The positron-neutrino correlation in ^{33}Ar decay was measured in the same experiment; for vanishing Fierz interference we find a=0.944 \pm 0.002 \pm 0.003. The ^{32}Ar and ^{33}Ar correlations, in combination with precision measurements of the half-lives, superallowed branching ratios and beta endpoint energies, will determine the isospin impurities of the superallowed transitions. These will provide useful tests of isospin-violation corrections used in deducing |V_{\rm ud}| which currently indicates non-unitarity of the KM matrix.Comment: 15 pages, 6 figure

    Physics Opportunities with Meson Beams

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    Over the past two decades, meson photo- and electro-production data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even nonexistent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state of-the-art meson-beam facility needs to be constructed. The present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.Comment: 46 pages, 10 figures, 4 table

    Electron Bernstein waves in spherical tokamak plasmas with "magnetic wells"

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    In addition to traditional regimes with monotonously increasing magnetic field, regimes with "magnetic wells" also occur in spherical tokamaks (STs). The magnetic field profile inversion modifies significantly the whole picture of the wave propagation and damping. Since the magnetic wells may become quite common with further improvement of ST performance, analysis of such configurations is of interest for assessment of EBW plasma heating an CD perspectives. In this paper the basic features of the EBWs propagation and damping for the second cyclotron harmonic in a slab model are considered.Comment: Proc. of 13-th Joint Workshop on ECE and ECRH, N.Novgorod, Russia May 17-20, 2004, 8 pages, 4 fig
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