4,210 research outputs found

    The genus Bolbelasmus in the western and southern regions of the Mediterranean Basin (Coleoptera: Geotrupidae: Bolboceratinae)

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    The Bolbelasmus Boucomont, 1911 species of the western and southern regions of the Mediterranean Basin (Northern Africa, Iberian Peninsula and France) are revised. The following three new species are described: Bolbelasmus brancoi Hillert & Král sp. nov. and Bolbelasmus howdeni Hillert & Král sp. nov., both from Spain and Gibraltar, and Bolbelasmus nikolajevi Hillert, Arnone, Král & Massa sp. nov. from Egypt, Libya and Tunisia. Bolbelasmus vaulogeri (Abeille de Perrin, 1898) stat. restit. is removed from synonymy with B. bocchus (Erichson, 1841) and reinstated as a separate species. Bolbelasmus romanorum Arnone & Massa, 2010 is considered a junior subjective synonym of B. vaulogeri. Lectotypes for Bolboceras bocchus Erichson, 1841 and Bolboceras vaulogeri Abeille de Perrin, 1898 are designated. Relevant diagnostic characters (head, pronotum, elytron, external male genitalia) are illustrated. Identifi cation keys for both males and females, and an annotated list of the Western Palaearctic representatives of the genus Bolbelasmus are presented. Finally, fi rst records are given for B. gallicus (Mulsant, 1842) from Corsica and the Midi-Pyrénées region of France, B. keithi Miessen & Trichas, 2011 from the Greek island of Rhodes, and B. unicornis (Schrank von Paula, 1789) from the Tuscany province of Italy

    Forecasting ocean warming impacts on seabird demography: a case study on the European storm petrel

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    Bottom-up climatic forcing has been shown to be influential for a variety of marine taxa, but evidence on seabird populations is scarce. Seasonal variation in environmental conditions can have an indirect effect on subsequent reproduction, which, given the longevity and single-brooding of seabirds, may affect population dynamics. Our study focuses on linking the effect of oceanographic conditions (from 1991 to 2013) to the fecundity and consequently pop - ulation growth rate of the Mediterranean subspecies of the European storm petrel Hydrobates pelagicus melitensis. In this study, we examined 23 yr of > 5400 capture–mark−recaptures (CMR) and modelled the probability of skipping reproduction as a function of oceanographic variables using CMR models. We demonstrate that a decrease in sea surface temperature in the pre-breeding period negatively influences skipping propensity, and therefore hypothesize that this behaviour would have significant influence on population abundance over time. For this reason, we analysed population growth as a function of skipping probability as affected by oceanographic conditions. We used stochastic demographic models to forecast the fate of the population, and evaluated contrasted environmental condition scenarios. As a result, we found that a decrease in frequency of cold winter events would probably reduce skipping propensity, with a positive effect on the population as a whole

    Determining the Physical Properties of the B Stars I. Methodology and First Results

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    We describe a new approach to fitting the UV-to-optical spectra of B stars to model atmospheres and present initial results. Using a sample of lightly reddened stars, we demonstrate that the Kurucz model atmospheres can produce excellent fits to either combined low dispersion IUE and optical photometry or HST FOS spectrophotometry, as long as the following conditions are fulfilled: 1) an extended grid of Kurucz models is employed, 2) the IUE NEWSIPS data are placed on the FOS absolute flux system using the Massa & Fitzpatrick (1999) transformation, and 3) all of the model parameters and the effects of interstellar extinction are solved for simultaneously. When these steps are taken, the temperatures, gravities, abundances and microturbulence velocities of lightly reddened B0-A0 V stars are determined to high precision. We also demonstrate that the same procedure can be used to fit the energy distributions of stars which are reddened by any UV extinction curve which can be expressed by the Fitzpatrick & Massa (1990) parameterization scheme. We present an initial set of results and verify our approach through comparisons with angular diameter measurements and the parameters derived for an eclipsing B star binary. We demonstrate that the metallicity derived from the ATLAS 9 fits to main sequence B stars is essentially the Fe abundance. We find that a near zero microturbulence velocity provides the best-fit to all but the hottest or most luminous stars (where it may become a surrogate for atmospheric expansion), and that the use of white dwarfs to calibrate UV spectrophotometry is valid.Comment: 17 pages, including 2 pages of Tables and 6 pages of Figures. Astrophysical Jounral, in pres

    Far-UV FUSE spectroscopy of the OVI resonance doublet in Sand2 (WO)

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    We present Far-Ultraviolet Spectroscopic Explorer (FUSE) spectroscopy of Sand 2, a LMC WO-type Wolf-Rayet star, revealing the OVI resonance P Cygni doublet at 1032-38A. These data are combined with HST/FOS ultraviolet and Mt Stromlo 2.3m optical spectroscopy, and analysed using a spherical, non-LTE, line-blanketed code. Our study reveals exceptional stellar parameters: T*=150,000K, v_inf=4100 km/s, log (L/Lo)=5.3, and Mdot=10^-5 Mo/yr if we adopt a volume filling factor of 10%. Elemental abundances of C/He=0.7+-0.2 and O/He=0.15(-0.05+0.10) by number qualitatively support previous recombination line studies. We confirm that Sand 2 is more chemically enriched in carbon than LMC WC stars, and is expected to undergo a supernova explosion within the next 50,000 yr.Comment: 17 pages, 4 figures, AASTeX preprint format. This paper will appear in a special issue of ApJ Letters devoted to the first scientific results from the FUSE missio

    Second-order-like cluster-monomer transition within magnetic fluids and its impact upon the magnetic susceptibility

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    The low-field (below 5 Oe) ac and dc magnetic response of a magnetic fluid [MF] sample in the range of 305 to 360 K and 410 to 455 K was experimentally and theoretically investigated. We found a systematic deviation of Curie's law, which predicts a linear temperature dependence of inverse initial susceptibility in the range of our investigation. This finding, as we hypothesized, is due to the onset of a second-order-like cluster-to-monomer transition with a critical exponent which is equal to 0.50. The susceptibility data were well fitted by a modified Langevin function, in which cluster dissociation into monomers, at the critical temperature [T*], was included. In the ac experiments, we found that T* was reducing from 381.8 to 380.4 K as the frequency of the applied field increases from 123 to 173 Hz. In addition, our ac experiments confirm that only monomers respond for the magnetic behavior of the MF sample above T*. Furthermore, our Monte Carlo simulation and analytical results support the hypothesis of a thermal-assisted dissociation of chain-like structures

    Linearization of nonlinear connections on vector and affine bundles, and some applications

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    A linear connection is associated to a nonlinear connection on a vector bundle by a linearization procedure. Our definition is intrinsic in terms of vector fields on the bundle. For a connection on an affine bundle our procedure can be applied after homogenization and restriction. Several applications in Classical Mechanics are provided

    Characterizing the magnetic fields of the first tau Sco analogues

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    The B0.2 V magnetic star tau Sco stands out from the larger population of massive OB stars due to its high X-ray activity, peculiar wind diagnostics and complex magnetic field. Recently, Petit et al. 2011 presented the discovery of the first two tau Sco analogues -- HD 66665 and HD 63425, identified by the striking similarity of their UV spectra to that of tau Sco. ESPaDOnS and Narval spectropolarimetric observations were obtained by the Magnetism in Massive Stars CFHT and TBL Large Programs, in order to characterize the stellar and magnetic properties of these stars. A magnetic field of similar surface strength was found on both stars, reinforcing the connection between the presence of a magnetic field and wind peculiarities. We present additional phase-resolved observations secured by the MiMeS collaboration for HD 66665 in order to measure its magnetic geometry, and correlate that geometry with diagnostics of mass-loss.Comment: to appear in the proceedings of Stellar polarimetry: From birth to death, Madison, USA, June 27 - June 30, 2011 (version 2 was updated to correct a typo in the arXiv metadata

    Experimental Quantum Cryptography With Classical Users

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    The exploit of quantum systems allows for insights that promise to revolutionise information processing, although a main challenge for practical implementations is technological complexity. Due to its feasibility, quantum cryptography, which allows for perfectly secure communication, has become the most prominent application of quantum technology. Nevertheless, this task still requires the users to be capable of performing quantum operations, such as state preparation or measurements in multiple bases. A natural question is whether the users' technological requirements can be further reduced. Here we demonstrate a novel quantum cryptography scheme, where users are fully classical. In our protocol, the quantum operations are performed by an untrusted third party acting as a server, which gives the users access to a superimposed single photon, and the key exchange is achieved via interaction-free measurements on the shared state. Our approach opens up new interesting possibilities for quantum cryptography networks.Comment: Main Text (9 pages, 3 figures) + Appendix (19 pages, 2 figures
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