9,560 research outputs found

    Three-loop Euler-Heisenberg Lagrangian and asymptotic analysis in 1+1 QED

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    In recent years, the Euler-Heisenberg Lagrangian has been shown to be a useful tool for the analysis of the asymptotic growth of the N-photon amplitudes at large N. Moreover, certain results and conjectures on its imaginary part allow one, using Borel analysis, to make predictions for those amplitudes at large loop orders. Extending work by G.V. Dunne and one of the authors to the three-loop level, but in the simpler context of 1+1 dimensional QED, we calculate the corresponding Euler-Heisenberg Lagrangian, analyse its weak field expansion, and study the congruence with predictions obtained from worldline instantons. We discuss the relevance of these issues for Cvitanovic's conjecture.Comment: 8 pages, 1 figure, Talk given by C. Schubert at QFEXT09, Univ. of Oklahoma, Norman, September 21 - 25, 2009, to appear in the conference proceeding

    Grapevine root transformation with Agrobacterium rhizogenes

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    Grapevine shoots were obtained from tissue cultures of cvs Barbera, Moscato bianco and Nebbiolo; their stems were wounded and inoculated with the following strains of Agrobacterium rhizogenes. A4, 8196, NCPP 2659, and 15834. Root production at the inoculation site was obtained in about 25% of the stems of all cultivars with all the bacterial strains, with the exception of NCPP 2659, which gave a lower root proliferation rate. Cultures of roots obtained after inoculation were established and their growth was enhanced by some media and by addition of cytokinins and auxins to the medium. Root cultures obtained after inoculation with the strain 8196 were genetically transformed, as shown by opine production. In contrast, opines were seldom detected in the root cultures obtained with the other bacterial strains. Light microscope observation showed that the cortex of transformed roots has more cell layers and a larger average cell size than in normal roots

    Interview with Fannie T. Taylor, Eunice Schubert, and Martin A. Stites

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    An interview with Fannie T. Taylor, Eunice Schubert, and Martin A. Stites regarding their experiences in rural western Kansas in the early 20th century. Recording includes various poems and folk songs. 00:00:32 - Early experiences in Bourbon County, KS 00:01:12 - Remedies 00:01:54 - Games 00:03:13 - Animals 00:03:46 - Sunday School and Church 00:04:09 - Snakes 00:04:32 - Turkeys 00:04:43 - Harvest 00:06:27 - School experiences and entertainment 00:08:48 - Sunday visits 00:09:21 - Learning about Crawfish 00:09:35 - Preserving food 00:10:03 - Cars 00:10:35 - Relationship with neighbors 00:11:28 - Spelling bees and ciphering matches 00:13:01 - Clothing 00:13:36 - The barn and chores 00:14:50 - Predicting weather 00:16:22 - Proverbs and sayings 00:17:17 - Nursery rhymes 00:17:58 - Picking blackberries and finding baby skunks 00:20:41 - Eunice Schubert, making molasses and taffy parties 00:22:55 - Making sauerkraut 00:24:07 - Playing split proverbs 00:25:27 - Martin S. Stites introduction 00:25:52 - Biographical information and early memories of life on a homestead 00:28:53 - Flood on Sugar Creek in 1878 00:31:26 - Singing experiences 00:33:13 - Moving west in 1886 00:36:33 - Building log cabins and establishing a farm 00:38:12 - Outbreak of typhoid fever in Boulder County, CO 00:38:52 - Move to Graham County, KS in 1910 00:41:20 - Introduction to songs 00:41:48 - Song, Give the Boy a Chance 00:45:08 - Song, Paper of Pins 00:47:00 - Introduction to song 00:47:13 - Song, I Wish I Had My Nickel Back 00:48:32 - Introduction to song 00:48:50 - Song, My Mama Told Me 00:49:15 - Song, My Little Gray Kitty 00:51:06 - Song, The Hunting Song 00:53:10 - Poem, Kansas Land 00:54:28 - Reading, Hans Stufienheimer and His Family Troubleshttps://scholars.fhsu.edu/sackett/1038/thumbnail.jp

    Quantum theory of light and noise polarization in nonlinear optics

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    We present a consistent quantum theory of the electromagnetic field in nonlinearly responding causal media, with special emphasis on χ(2)\chi^{(2)} media. Starting from QED in linearly responding causal media, we develop a method to construct the nonlinear Hamiltonian expressed in terms of the complex nonlinear susceptibility in a quantum mechanically consistent way. In particular we show that the method yields the nonlinear noise polarization, which together with the linear one is responsible for intrinsic quantum decoherence.Comment: 4 pages, no figure

    Statistical model of the powder flow regulation by nanomaterials

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    Fine powders often tend to agglomerate due to van der Waals forces between the particles. These forces can be reduced significantly by covering the particles with nanoscaled adsorbates, as shown by recent experiments. In the present work a quantitative statistical analysis of the effect of powder flow regulating nanomaterials on the adhesive forces in powders is given. Covering two spherical powder particles randomly with nanoadsorbates we compute the decrease of the mutual van der Waals force. The dependence of the force on the relative surface coverage obeys a scaling form which is independent of the used materials. The predictions by our simulations are compared to the experimental results.Comment: 18 pages, 9 figures, 1 table, LaTeX; reviewed version with minor changes, published (Powder Technology

    Effects of vesicular-arbuscular mycorrhizal fungi on micropropagated grapevines: Influence of endophyte strain, P fertilization and growth medium

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    Einfluß vesikulĂ€r-arbuskulĂ€rer Mykorrhizapilze auf in vitro vermehrte Reben: Wirkung von Pilzstamm, PhosphatdĂŒngung und KultursubstratIn vitro vermehrte Pflanzen der Unterlagssorte Vitis berlandieri x V. rupestris 1103 P wurden in steriles Substrat verpflanzt, das mit steigenden P-Gaben angereichert war, und wĂ€hrend der Anpassungsphase mit verschiedenen Arten vesikulĂ€r-arbuskulĂ€rer Mykorrhizapilze (VAM) beimpft. In dem Substrat ohne P-DĂŒngung förderten alle Pilzarten das Rebenwachstum; der positive Einfluß der Beimpfung war jedoch mit zunehmender DĂŒngungsstufe verwischt. Zwei Pilzarten waren indessen auch noch bei der höchsten P-Konzentration in der Lage, das Pflanzenwachstum zu steigern. In einem weiteren Versuch wurde der Einfluß der VAM-Art Glomus caledonicum (NICOL. et GERD.) TRAPPE et GERD. in einem Torf/Sand-Gemisch geprĂŒft, das mit 0 oder 10 % Erde versetzt war. Obwohl der VAM-Pilz die Wurzeln in beiden FĂ€llen besiedelte, wurde eine signifikante Wachstumssteigerung nur in dem Erde enthaltenden Substrat festgestellt

    HD DVD substrates for surface enhanced Raman spectroscopy analysis : fabrication, theoretical predictions and practical performance

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    Commercial HD DVDs provide a characteristic structure of encoding pits which were utilized to fabricate cost efficiently large area SERS substrates for chemical analysis. The study targets the simulation of the plasmonic structure of the substrates and presents an easily accessible fabrication process to obtain highly sensitive SERS active substrates. The theoretical simulation predicted the formation of supermodes under optimized illumination conditions, which were verified experimentally. First tests of the developed SERS substrates demonstrated their excellent potential for detecting vitamin A and pro- vitamin A at low concentration levels

    Post Quantum Cryptography from Mutant Prime Knots

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    By resorting to basic features of topological knot theory we propose a (classical) cryptographic protocol based on the `difficulty' of decomposing complex knots generated as connected sums of prime knots and their mutants. The scheme combines an asymmetric public key protocol with symmetric private ones and is intrinsecally secure against quantum eavesdropper attacks.Comment: 14 pages, 5 figure

    Fullerene van der waals Oligomers as electron traps

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    Density functional theory calculations indicate that van der Waals fullerene dimers and larger oligomers can form interstitial electron traps in which the electrons are even more strongly bound than in isolated fullerene radical anions. The fullerenes behave like super atoms , and the interstitial electron traps represent one-electron intermolecular σ-bonds. Spectroelectrochemical measurements on a bis-fullerene-substituted peptide provide experimental support. The proposed deep electron traps are relevant for all organic electronics applications in which non-covalently linked fullerenes in van der Waals contact with one another serve as n-type semiconductors
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