3,108 research outputs found

    First record of Xenopsylla gratiosa Jordan & Rothschild, 1923 from the Maltese Islands (Siphonaptera: Pulicidae)

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    Xenopsylla gratiosa is reported for the first time from the Maltese Islands. The species was found in an abandoned nest of a Cory’s Shearwater, Calonectris diomedea on the island of Filfla. Brief notes are included on previous records of fleas from the Maltese Islands and taxonomic, distributional and ecological notes are provided for Xenopsylla gratiosapeer-reviewe

    The spherical symmetry Black hole collapse in expanding universe

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    The spherical symmetry Black holes are considered in expanding background. The singularity line and the marginally trapped tube surface behavior are discussed. In particular, we address the conditions whether dynamical horizon forms for these cosmological black holes. We also discuss about the cosmological constant effect on these black hole and the redshift of the light which comes from the marginally trapped tube surface.Comment: 7 pages, 3 figures. Accepted for publication in International Journal of Modern Physics D (IJMPD). arXiv admin note: text overlap with arXiv:gr-qc/0308033 and arXiv:gr-qc/030611

    Atomic data from the Iron Project.XLIII. Transition probabilities for Fe V

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    An extensive set of dipole-allowed, intercombination, and forbidden transition probabilities for Fe V is presented. The Breit-Pauli R-matrix (BPRM) method is used to calculate 1.46 x 10^6 oscillator strengths for the allowed and intercombination E1 transitions among 3,865 fine-structure levels dominated by configuration complexes with n <= 10 and l <= 9. These data are complemented by an atomic structure configuration interaction (CI) calculation using the SUPERSTRUCTURE program for 362 relativistic quadrupole (E2) and magnetic dipole (M1) transitions among 65 low-lying levels dominated by the 3d^4 and 3d^ 4s configurations. Procedures have been developed for the identification of the large number of fine-structure levels and transitions obtained through the BPRM calculations. The target ion Fe VI is represented by an eigenfunction expansion of 19 fine-structure levels of 3d^3 and a set of correlation configurations. Fe V bound levels are obtained with angular and spin symmetries SL\pi and J\pi of the (e + Fe VI) system such that 2S+1 = 5,3,1, L <= 10, J <= 8 of even and odd parities. The completeness of the calculated dataset is verified in terms of all possible bound levels belonging to relevant LS terms and transitions in correspondence with the LS terms. The fine-structure averaged relativistic values are compared with previous Opacity Project LS coupling data and other works. The 362 forbidden transition probabilities considerably extend the available data for the E2 and M1 transtions, and are in good agreement with those computed by Garstang for the 3d^4 transitions.Comment: 19 pages, 1 figure. This paper marks the beginning of a large-scale effort of ab initio atomic calculations that should eventually lead to re-calculation of accurate iron opacities. Astron. Astrophys. Suppl. Ser. (in press

    Charged black holes in Vaidya backgrounds: Hawking's Radiation

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    In this paper we propose a class of embedded solutions of Einstein's field equations describing non-rotating Reissner-Nordstrom-Vaidya and rotating Kerr-Newman-Vaidya black holes.Comment: 30 pages, latex file, no figure

    Optoelectronic and antimicrobial activity of composite zinc oxide and cadmium sulphide quantum dots and application in water treatment

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    In the present study, we report the synthesis of composite zinc oxide and cadmium sulphidenanoparticles by a chemical route. ZnO–CdS nanocomposites have been gaining much importance as they show fascinating opto-electronic properties such as tunable band gap and the nanomaterials are suitable for fast photon absorption, transportation and collection. The prepared composite nanoparticles have been characterized by UV–VIS absorption, X-ray diffraction (XRD) and TEM, AFM and FTIR observation. UV-VIS optical spectroscopy study has been carried out to determine the band gap of the composite zinc oxide and cadmium sulphide thin film and it shows a blue shift with respect to the bulk value. The nanocomposites show enhanced optio -electronic properties compared to the individual constituents. The band gap of CdS–ZnO nanocomposites depend on various experimental parameters such as reaction time, concentrations of cadmium salt, and also chemical nature of the cadmium salt. The band gap value of the ZnO–CdS nanocrystalline films are obtained in the range of 3.88–4.14 eV which is higher than that of bulk value of ZnO (3.3 eV) and CdS (2.42 eV). The synthesized nanoparticles exhibited high antibacterial activity and can be used for water purification

    Medlycott's drawings of Maltese natural history

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    In 186lWilliam Tallack wrote: "William C. P. Medlycott, Esq., an English gentleman, who spends a part of almost every winter in Malta, has also devoted much careful observation to its birds and ichthyology. He has drawn a series of very accurate coloured representations of the fish and crustaceans of the island, which, if published would be a valuable contribution to the natural history of Europe" (Tallack, 1861). Thirty-two years later, this paragraph was partly quoted by 1. H. Cooke (1893), who added the question "Can any of our readers inform us of the whereabouts of these drawings?" The aim of this note is to bring to light the whereabouts of Medlycott's drawings, with the hope that someone in future may find the time and resources to make an in-depth study of them.peer-reviewe

    The presence of Gekkonidae (Reptilia : Squamata) on Fungus Rock and Filfla (Maltese Archipelago)

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    The presence of Hemidactylus turcicus (L.) on Fungus Rock is recorded for the first time, while its presence on Filfla is confirmed. Other specimens were observed on Filfla and one was tentatively identified as Tarentola mauritanica (L.).peer-reviewe

    Red data book for the Maltese Islands

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    A study detailing the various flora and fauna found on the Maltese Islands, these includes some 1000 flowering plants, 1000 lower plants, some 50 molluscs, 500 species of arachnids, 100 crustaceans, more than 3000 insects, 1 amphibian, 9 reptiles, 160 birds and 20 mammals. This does not include migratory birds and insects and marine animals, if these were to be included the number would nearly double.peer-reviewe
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