1,203 research outputs found

    Metric perturbation from inflationary magnetic field and generic bound on inflation models

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    There is an observational indication of extragalactic magnetic fields. No known astrophysical process can explain the origin of such large scale magnetic fields, which motivates us to look for their origin in primordial inflation. By solving the linearized Einstein equations, we study metric perturbations sourced by magnetic fields that are produced during inflation. This leads to a simple but robust bound on the inflation models by requiring that the induced metric perturbation should not exceed the observed value 10^-5. In case of the standard single field inflation model, the bound can be converted into a lower bound on the Hubble parameter during inflation.Comment: 14 page

    Poor development of transmitting tissue in tetraploid grape pistils causing inhibition of pollen tube growth

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    Anatomical investigations were carried out to study the cause of poor berry set in tetraploid grape cultivars, Using 6 diploid and 6 tetraploid grape cultivars, the development of the transmitting tissue (TT) and pollen tube growth in their pistils were examined. The rates of berry set and seed number per berry were also investigated. TT was found to be cylindrical in the style and elliptic-conical in the ovaries. In the middle part of the ovary, the TT had developed along the inner surface of each septum projecting from both sides of the ovary wall. In the middle style, the TT diameter of tetraploid cultivars was larger than in diploid cultivars, However, TT development in the septum was markedly poorer in most of the tetraploid cultivars examined except for cv, Fujiminori where a sufficient number of seeded berries developed on the clusters. Most pollen tubes penetrating into the ovary tissue were inhibited to grow further in tetraploid cultivars except for cv, Fujiminori, These findings suggest that the poor set of normally seeded berries in most tetraploid grapes may be due to poor development of TT in the septum, which severely inhibits pollen tube penetration into the micropyle.

    Higher Order Corrections to the Primordial Gravitational Wave Spectrum and its Impact on Parameter Estimates for Inflation

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    We study the impact of the use of the power series expression for the primordial tensor spectrum on parameter estimation from future direct detection gravitational wave experiments. The spectrum approximated by the power series expansion may give large deviation from the true (fiducial) value when it is normalized at CMB scale because of the large separation between CMB and direct detection scales. We derive the coefficients of the higher order terms of the expansion up to the sixth order within the framework of the slow-roll approximation and investigate how well the inclusion of higher order terms improves the analytic prediction of the spectrum amplitude by comparing with numerical results. Using the power series expression, we consider future constraints on inflationary parameters expected from direct detection experiments of the inflationary gravitational wave background and show that the truncation of the higher order terms can lead to incorrect evaluation of the parameters. We present two example models; a quadratic chaotic inflation model and mixed inflaton and curvaton model with a quartic inflaton potential.Comment: 25 pages, 7 figures, revised version accepted by JCA

    Non-Gaussianity from Symmetry

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    We point out that a light scalar field fluctuating around a symmetry-enhaced point can generate large non-Gaussianity in density fluctuations. We name such a particle as an "ungaussiton", a scalar field dominantly produced by the quantum fluctuations,generating sizable non-Gaussianity in the density fluctuations. We derive a consistency relation between the bispectrum and the trispectrum, tau_NL = 10^3 f_NL^(4/3), which can be extended to arbitrary high order correlation functions. If such a relation is confirmed by future observations, it will strongly support this mechanism.Comment: 26 pages, 1 figure;v2 discussion and references added. To appear in JCA

    Effect of shoot vigor on the development of transmitting tissue and pollen tube growth in pistils of tetraploid grape, cv. Pione

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    Effects of shoot vigor on the development of transmitting tissue (TT) and pollen tube growth in pistils of Pione grapevines (a hybrid of Vitis vinifera L. and V. labrusca L., tetraploid) were investigated anatomically. Shoot vigor was reduced by root zone restriction and pre-bloom shoot tipping, and was increased by severe winter pruning and application of high concentration fertilizer. The TT development in long and short shoots of the vines without root restriction was also compared. In cross sections of the upper and middle ovaries, a thicker TT and more pollen tubes were found in root zone-restricted vines compared to unrestricted vines. Also, thicker TT and more pollen tubes were observed in less vigorous, short shoots of unrestricted vines. Tipping did not improve the TT development. However, spur pruning and application of high concentration fertilizer to root zone-restricted vines did not inhibit the TT development and pollen tube growth, though shoots grew vigorously. From these results, we conclude that promoted TT development in less vigorous shoots of Pione grapevines allows for more pollen tubes to penetrate into the ovary, resulting in the production of acceptable clusters with a sufficient number of seeded berries.

    Inhomogeneous non-Gaussianity

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    We propose a method to probe higher-order correlators of the primordial density field through the inhomogeneity of local non-Gaussian parameters, such as f_NL, measured within smaller patches of the sky. Correlators between n-point functions measured in one patch of the sky and k-point functions measured in another patch depend upon the (n+k)-point functions over the entire sky. The inhomogeneity of non-Gaussian parameters may be a feasible way to detect or constrain higher-order correlators in local models of non-Gaussianity, as well as to distinguish between single and multiple-source scenarios for generating the primordial density perturbation, and more generally to probe the details of inflationary physics.Comment: 16 pages, 2 figures; v2: Minor changes and references added. Matches the published versio

    Non-Gaussianity from isocurvature perturbations

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    We develop a formalism to study non-Gaussianity in both curvature and isocurvature perturbations. It is shown that non-Gaussianity in the isocurvature perturbation between dark matter and photons leaves distinct signatures in the CMB temperature fluctuations, which may be confirmed in future experiments, or possibly, even in the currently available observational data. As an explicit example, we consider the QCD axion and show that it can actually induce sizable non-Gaussianity for the inflationary scale, H_{inf} = O(10^9 - 10^{11})GeV.Comment: 24 pages, 6 figures; references added; version to appear in JCA

    The production of copper phthalocyanine and/or its derivatives

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    This document discusses the production of copper phthalocyanine and/or its derivatives, which are useful for dye pigments. The method described uses urea, a copper compound and/or a catalyst which have been suspended in an inert reaction medium. The copper compound, catalyst and urea fused and the reaction is performed by using the obtained fusion. The advantages of the invention are listed

    Closed String Tachyon Condensation on Twisted Circles

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    We study IIA/B string theory compactified on twisted circles. These models possess closed string tachyons and reduce to type 0B/A theory in a special limit. Using methods of gauged linear sigma models and mirror symmetry we construct a conformal field theory which interpolates between these models and flat space via an auxiliary Liouville direction. Interpreting motion in the Liouville direction as renormalization group flow, we argue that the end point of tachyon condensation in all these models (including 0B/A theory) is supersymmetric type II theory. We also find a zero-slope limit of these models which is best described in a T-dual picture as a type II NS-NS fluxbrane. In this limit tachyon condensation is an interesting and well posed problem in supergravity. We explicitly determine the tachyon as a fluctuation of supergravity fields, and perform a rudimentary numerical analysis of the relevant flows.Comment: 21 pages plus appendices (12 pages), harvmac, 1 fig, v2: minor changes and references added, v3: minor changes version published in JHE
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