461 research outputs found

    CALCULATION OF QUASI-TEM WAVES BY SERIES EXPANSION IN POWERS OF FREQUENCY

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    CALCULATION OF GUIDED WAVES BY EXPANSION IN POWERS OF THE FREQUENCY

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    Rhabdotosperma saudiarabicum (Scrophulariaceae), a new species from Saudi Arabia

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    A new species of (Scrophulariaceae) is described from southwestern Saudi Arabia. For 75 years, the species was confused with and . The new species is illustrated with information on identification, distribution, specimens examined, habitat, conservation status, phenology, etymology, and taxonomic notes

    DNA barcoding of the genus Verbascum (Scrophulariaceae) in the Arabian Peninsula

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    Verbascum and Rhabdotosperma are members of the family Scrophulariaceae. The first genus comprises approximately 360 species from almost all parts of the world, while the second contains a total of 8 species from tropical Africa and the Arabian Peninsula. Since 1977, the relationships between Verbascum and Rhabdotosperma continue to be contested. The present study aims to present the phylogenetic relationships and status among Verbascum species in the Arabian Peninsula. For phylogenetic analyses, maximum parsimony and Bayesian inference were performed. In total, 236 DNA sequences from 59 specimens of Arabian Verbascum were analysed. The phylogenetic analysis of one nuclear (ITS) and three chloroplastic (rbcL, matK, trnL) markers confirmed the monophyly of Verbascum, including the genus Rhabdotosperma. In addition to presenting novel phylogenetic relationships among the different Verbascum species in the Arabian Peninsula, our study reduced the species count of Arabian Verbascum to 16. Moreover, the phylogenetic analysis strongly supports the reinstatement of the genus Rhabdotosperma into Verbascum based on the Bayesian and maximum parsimony analyses

    DNA barcoding of the genus Verbascum (Scrophulariaceae) in the Arabian Peninsula

    Get PDF
    Verbascum and Rhabdotosperma are members of the family Scrophulariaceae. The first genus comprises approximately 360 species from almost all parts of the world, while the second contains a total of 8 species from tropical Africa and the Arabian Peninsula. Since 1977, the relationships between Verbascum and Rhabdotosperma continue to be contested. The present study aims to present the phylogenetic relationships and status among Verbascum species in the Arabian Peninsula. For phylogenetic analyses, maximum parsimony and Bayesian inference were performed. In total, 236 DNA sequences from 59 specimens of Arabian Verbascum were analysed. The phylogenetic analysis of one nuclear (ITS) and three chloroplastic (rbcL, matK, trnL) markers confirmed the monophyly of Verbascum, including the genus Rhabdotosperma. In addition to presenting novel phylogenetic relationships among the different Verbascum species in the Arabian Peninsula, our study reduced the species count of Arabian Verbascum to 16. Moreover, the phylogenetic analysis strongly supports the reinstatement of the genus Rhabdotosperma into Verbascum based on the Bayesian and maximum parsimony analyses

    Characterisation of a new VUV beamline at the Daresbury SRS using a dispersed fluorescence apparatus incorporating CCD detection

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    The design and performance of a new normal incidence monochromator at the Daresbury Synchrotron Radiation Source, optimised for experiments requiring high flux of vacuum-UV radiation, are described. The re-developed beamline 3.1, based on the Wadsworth design of monochromator, is the source of tunable vacuum-UV photons in the range 4 – 31 eV, providing over two orders of magnitude more flux than the vacuum-UV, Seya monochromator in its previous manifestation. The undispersed and dispersed fluorescence spectra resulting from photoexcitation of N2_2, CO2_2, CF4_4 and C6_6F6_6 are presented. Emitting species observed were N2+_2^+ B2Σu+^2\Sigma_u^+ - X2Σg+^2\Sigma_g^+, CO2+_2^+ A2Πu^2\Pi_u - X2Πg^2\Pi_g and B2Σu+^2\Sigma_u^+ - X2Πg^2\Pi_g, CF4_4+^+ C2^2T2_2 - X2^2T1_1 and C2^2T2_2 - A2^2T2_2, CF3_3* 2^2A2^’_2 - 2^2A2^”_2, and C6_6F6+_6^+ B2^2A2u_{2u} - X2^2E1g_{1g}. A CCD multi-channel detector has significantly reduced the time period needed to record dispersed fluorescence spectra with a comparable signal-to-noise ratio
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