757 research outputs found

    Low-noise slot antenna SIS mixers

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    The 3s Proton Occupancy in 206-Pb

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    This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440

    Self-generated magnetic flux in YBa2_2Cu3_3O7x_{7-x} grain boundaries

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    Grain boundaries in YBa2_2Cu3_3O7x_{7-x} superconducting films are considered as Josephson junctions with a critical current density jc(x)j_c(x) alternating along the junction. A self-generated magnetic flux is treated both analytically and numerically for an almost periodic distribution of jc(x)j_c(x). We obtained a magnetic flux-pattern similar to the one which was recently observed experimentally.Comment: 7 pages, 3 figure

    Implementation and Validation of Schapery-Rand Anisotropic Viscoelasticity Model for Super-Pressure Balloons

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    The thin film used for the NASA Ultra Long Duration Balloons (ULDB) shows con-siderable time-dependent behaviour. Furthermore, experiments on scaled ULDB balloons have revealed that wrinkles are present over a wide range of pressures. A numerical model has been developed describing the nonlinear anisotropic viscoelastic material behaviour by means of a Schapery-type model and this model has been extended to model wrinkling by means of a user-defined subroutine in the finite-element package ABAQUS. After a description of the viscoelastic modelling approach, a lobe of a 48 gore ULDB flat facet balloon is modelled and compared to experimental results. Additionally two test cases of anisotropic wrinkling are presented, one involving a flat membrane and one a cylindrical balloon structure. I

    Accuracy and Stability of Computing High-Order Derivatives of Analytic Functions by Cauchy Integrals

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    High-order derivatives of analytic functions are expressible as Cauchy integrals over circular contours, which can very effectively be approximated, e.g., by trapezoidal sums. Whereas analytically each radius r up to the radius of convergence is equal, numerical stability strongly depends on r. We give a comprehensive study of this effect; in particular we show that there is a unique radius that minimizes the loss of accuracy caused by round-off errors. For large classes of functions, though not for all, this radius actually gives about full accuracy; a remarkable fact that we explain by the theory of Hardy spaces, by the Wiman-Valiron and Levin-Pfluger theory of entire functions, and by the saddle-point method of asymptotic analysis. Many examples and non-trivial applications are discussed in detail.Comment: Version 4 has some references and a discussion of other quadrature rules added; 57 pages, 7 figures, 6 tables; to appear in Found. Comput. Mat

    Electroweak Corrections to the Charged Higgs Boson Decay into Chargino and Neutralino

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    The electroweak corrections to the partial widths of the H+χ~i+χ~j0(i=1,j=1,2)H^+ \to \tilde{\chi}^+_i \tilde{\chi}_j^0 (i=1,j=1,2) decays including one-loop diagrams of the third generation quarks and squarks, are investigated within the Supersymmetric Standard Model. The relative corrections can reach the values about 10%, therefore they should be taken into account for the precise experimental measurement at future colliders.Comment: 21 pages, 6 eps figures, 1 Latex fil

    Prospects for heavy supersymmetric charged Higgs boson searches at hadron colliders

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    We investigate the production of a heavy charged Higgs boson at hadron colliders within the context of the MSSM. A detailed study is performed for all important production modes and basic background processes for the t\bar{t}b\bar{b} signature. In our analysis we include effects of initial and final state showering, hadronization, and principal detector effects. For the signal production rate we include the leading SUSY quantum effects at high \tan\beta>~ mt/mb. Based on the obtained efficiencies for the signal and background we estimate the discovery and exclusion mass limits of the charged Higgs boson at high values of \tan\beta. At the upgraded Tevatron the discovery of a heavy charged Higgs boson (MH^+ >~ 200 GeV) is impossible for the tree-level cross-section values. However, if QCD and SUSY effects happen to reinforce mutually, there are indeed regions of the MSSM parameter space which could provide 3\sigma evidence and, at best, 5\sigma charged Higgs boson discovery at the Tevatron for masses M_H^+<~ 300 GeV and M_H^+<~ 250 GeV, respectively, even assuming squark and gluino masses in the (500-1000) GeV range. On the other hand, at the LHC one can discover a H^+ as heavy as 1 TeV at the canonical confidence level of 5\sigma; or else exclude its existence at 95% C.L. up to masses ~ 1.5 TeV. Again the presence of SUSY quantum effects can be very important here as they may shift the LHC limits by a few hundred GeV.Comment: Latex2e, 44 pages, 15 figures, 6 tables, uses JHEP3.sty, axodraw.sty. Comments added. Discussion on QCD factors clarified. Added discussion on uncertainties. Change of presentation of Tables 4 and 5 and Fig.6. Results and conclusions unchanged. Version accepted in JHE

    Primer informe de Fusarium incarnatum (Desm.) Sacc. afectando al cultivo del garbanzo en Cuba

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    The objective of the work was to characterize isolates of Fusarium sp. from chickpea (Cicer arietinum L.) morphologically and molecularly. For this, the morphological characterization of the isolates of Fusarium sp. was conducted by using a taxonomic key and, for their molecular identification, DNA extraction, amplification of the translation and elongation factor 1α (tef-1α) gene, purification and sequencing of the amplified fragments were performed. The results allowed reporting the first identification of a new Fusarium species on chickpea in Cuba [Fusarium incarnatum (Desm.) Sacc.], a species belonging to the Fusarium incarnatum-equiseti species complex (FIESC). The Cuban strains were phylogenetically clustered with the FIESC 15 group. This is the first report of F. incarnatum associated with chickpea in Cuba.El trabajo tuvo como objetivo caracterizar morfológica y molecularmente aislamientos de Fusarium sp. procedentes de plantas de garbanzo (Cicer arietinum L.). Para ello, se realizó la caracterización morfológica de los aislados de Fusarium sp. mediante el uso de una clave taxonómica. Para la identificación molecular se realizó la extracción de ADN, amplificación del gen que codifica para el factor de elongación y traducción 1α (tef- 1α), purificación de los fragmentos amplificados y su secuenciación. Los resultados permitieron informar, por primera vez en Cuba, una nueva especie de Fusarium en el garbanzo [Fusarium incarnatum (Desm.) Sacc.], incluida en el clado Incarnatum, que pertenece al complejo de especies Fusarium incarnatum-equiseti (FIESC). Las cepas cubanas se agruparon filogenéticamente con el grupo FIESC 15. Este es el primer informe de F. incarnatum asociado al garbanzo en Cuba
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