166 research outputs found

    Living Plants in Hawaii Attacked by Coptotermes formosanus

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    Forty-seven species of living plants in 27 families were found infested by Coptotermes formosanus Shiraki in Hawaii. The symptoms caused by the infestations were dependent on the mode of attack. Although an actual value was not placed on the economic losses caused by the attacks, evidence indicates that the losses are substantial

    Lowland Soils for Rice Cultivation in Ghana

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    Abundance and Distribution of the Three Species of Symbiotic Protozoa in the Hindgut of Coptotermes formosanus (Isoptera: Rhinotermitidae)

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    Workers, soldiers, nymphs and alates of the Formosan subterranean termite, Coptotermes formosanus Shiraki, all harbored the same 3 species of protozoa. Workers, nymphs, and alates had a larger number of protozoa than the soldiers. The relative abundance of the protozoa differed in the different castes. In the worker, Holomastigotoides hartmanni Koidzumi was the predominant species in numbers, followed by Pseudotrichonympha grassii Koidzumi and Spirotrichonympha leidyi Koidzumi while in the alate. S. leidyi was predominant. Each protozoan species apparently occupied a more or less specific location in the worker's hindgut. P. grassii was predominant in the first pouch, H. hartmanni in the second, and H. hartmanni and S. leidyi in the third pouch and excreta. This may indicate a difference in digestive roles of the protozoa and/or a difference in the oxygen requirements of the 3 species. There were no significant differences in the total number of protozoa found in the workers from 3 different colonies

    Time varying α\alpha in N=8 extended Supergravity

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    There has been some evidence that the fine structure "constant" α\alpha may vary with time. We point out that this variation can be described by a scalar field in some supergravity theory in our toy model, for instance, the N=8 extended supergravity in four dimensions which can be accommodated in M-theory.Comment: 5 pages,1 figures. Accepted for publication in JHE

    Limits on Cosmological Variation of Strong Interaction and Quark Masses from Big Bang Nucleosynthesis, Cosmic, Laboratory and Oklo Data

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    Recent data on cosmological variation of the electromagnetic fine structure constant from distant quasar (QSO) absorption spectra have inspired a more general discussion of possible variation of other constants. We discuss variation of strong scale and quark masses. We derive the limits on their relative change from (i) primordial Big-Bang Nucleosynthesis (BBN); (ii) Oklo natural nuclear reactor, (iii) quasar absorption spectra, and (iv) laboratory measurements of hyperfine intervals.Comment: 10 pages 2 figurs: second version have several references added and some new comment

    Towards a sensitive search for variation of the fine structure constant using radio-frequency E1 transitions in atomic dysprosium

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    It has been proposed that the radio-frequency electric-dipole (E1) transition between two nearly degenerate opposite-parity states in atomic dysprosium should be highly sensitive to possible temporal variation of the fine structure constant (α\alpha) [V. A. Dzuba, V. V. Flambaum, and J. K. Webb, Phys. Rev. A {\bf 59}, 230 (1999)]. We analyze here an experimental realization of the proposed search in progress in our laboratory, which involves monitoring the E1 transition frequency over a period of time using direct frequency counting techniques. We estimate that a statistical sensitivity of |\adota| \sim 10^{-18}/yr may be achieved and discuss possible systematic effects that may limit such a measurement.Comment: 8 pages, 7 figure

    Time Variations in the Scale of Grand Unification

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    We study the consequences of time variations in the scale of grand unification, MUM_U, when the Planck scale and the value of the unified coupling at the Planck scale are held fixed. We show that the relation between the variations of the low energy gauge couplings is highly model dependent. It is even possible, in principle, that the electromagnetic coupling α\alpha varies, but the strong coupling α3\alpha_3 does not (to leading approximation). We investigate whether the interpretation of recent observations of quasar absorption lines in terms of time variation in α\alpha can be accounted for by time variation in MUM_U. Our formalism can be applied to any scenario where a time variation in an intermediate scale induces, through threshold corrections, time variations in the effective low scale couplings.Comment: 14 pages, revtex4; Updated observational results and improved statistical analysis (section IV); added reference

    Measuring α\alpha in the Early Universe: CMB Temperature, Large-Scale Structure and Fisher Matrix Analysis

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    We extend our recent work on the effects of a time-varying fine-structure constant α\alpha in the cosmic microwave background, by providing a thorough analysis of the degeneracies between α\alpha and the other cosmological parameters, and discussing ways to break these with both existing and/or forthcoming data. In particular, we present the state-of-the-art CMB constraints on α\alpha, through a combined analysis of the BOOMERanG, MAXIMA and DASI datasets. We also present a novel discussion of the constraints on α\alpha coming from large-scale structure observations, focusing in particular on the power spectrum from the 2dF survey. Our results are consistent with no variation in α\alpha from the epoch of recombination to the present day, and restrict any such (relative) variation to be less than about 4%. We show that the forthcoming MAP and (particularly) Planck experiments will be able to break most of the currently existing degeneracies between α\alpha and other parameters, and measure α\alpha to better than percent accuracy.Comment: 11 pages in RevTex4 format. Low-quality figures to comply with arXiv restrictions (better ones available from the authors). v2: Updated Oklo discussion, plus other cosmetic changes. Version to appear in Phys Rev

    Constraints on the Variations of the Fundamental Couplings

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    We reconsider several current bounds on the variation of the fine-structure constant in models where all gauge and Yukawa couplings vary in an interdependent manner, as would be expected in unified theories. In particular, we re-examine the bounds established by the Oklo reactor from the resonant neutron capture cross-section of 149Sm. By imposing variations in \Lambda_{QCD} and the quark masses, as dictated by unified theories, the corresponding bound on the variation of the fine-structure constant can be improved by about 2 orders of magnitude in such theories. In addition, we consider possible bounds on variations due to their effect on long lived \alpha- and \beta-decay isotopes, particularly 147Sm and 187Re. We obtain a strong constraint on \Delta \alpha / \alpha, comparable to that of Oklo but extending to a higher redshift corresponding to the age of the solar system, from the radioactive life-time of 187Re derived from meteoritic studies. We also analyze the astrophysical consequences of perturbing the decay Q values on bound state \beta-decays operating in the s-process.Comment: 25 pages, latex, 5 eps figure

    Models of quintessence coupled to the electromagnetic field and the cosmological evolution of alpha

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    We study the change of the effective fine structure constant in the cosmological models of a scalar field with a non-vanishing coupling to the electromagnetic field. Combining cosmological data and terrestrial observations we place empirical constraints on the size of the possible coupling and explore a large class of models that exhibit tracking behavior. The change of the fine structure constant implied by the quasar absorption spectra together with the requirement of tracking behavior impose a lower bound of the size of this coupling. Furthermore, the transition to the quintessence regime implies a narrow window for this coupling around 10510^{-5} in units of the inverse Planck mass. We also propose a non-minimal coupling between electromagnetism and quintessence which has the effect of leading only to changes of alpha determined from atomic physics phenomena, but leaving no observable consequences through nuclear physics effects. In doing so we are able to reconcile the claimed cosmological evidence for a changing fine structure constant with the tight constraints emerging from the Oklo natural nuclear reactor.Comment: 13 pages, 10 figures, RevTex, new references adde
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