66 research outputs found

    Testing the predicted mass-loss bi-stability jump at radio wavelengths

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    In this study, we test the theoretically predicted mass-loss behaviour as a function of stellar effective temperature across the so-called `bi-stability' jump (BSJ). We gathered radio observations of 30 OB supergiants (O8-B3). We derived the radio mass-loss rates and wind efficiencies, and compared our results with Halpha mass-loss rates and predictions based on radiation-driven wind models. he wind efficiency shows the possible presence of a local maximum around an effective temperature of 21~000 K -- in qualitative agreement with predictions. We also find that the radio mass-loss rates show good agreement with empirical Halpha rates. However, the empirical mass-loss rates are larger than the predicted rates from radiation-driven wind theory for objects above the BSJ temperature, whilst they are smaller for the rest. A new wind momenta-luminosity relation for O8-B0 stars has been derived.Comment: 13 pages, 13 figures, A&

    Natural Diagonal Riemannian Almost Product and Para-Hermitian Cotangent Bundles

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    We obtain the natural diagonal almost product and locally product structures on the total space of the cotangent bundle of a Riemannian manifold. We find the Riemannian almost product (locally product) and the (almost) para-Hermitian cotangent bundles of natural diagonal lift type. We prove the characterization theorem for the natural diagonal (almost) para-K\"ahlerian structures on the total spaces of the cotangent bundle.Comment: 10 pages, will appear in Czechoslovak Mathematical Journa

    Managerial Views of Corporate Impacts and Dependencies on Ecosystem Services : A Case of International and Domestic Forestry Companies in China

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    A line of research is emerging investigating the private sector impacts and dependencies on critical biodiversity and ecosystem services, and related business risks and opportunities. While the ecosystem services narrative is being forwarded globally as a key paradigm for promoting business sustainability, there is scarce knowledge of how these issues are considered at managerial level. This study thus investigates managerial views of corporate sustainability after the ecosystem services concept. We analyse interviews conducted with 20 managers from domestic and international forestry companies operating with a plantation-based business model in China. Content analysis was employed to analyse the data, with a focus on four key areas: (1) interviewee familiarity with the ecosystem services concept; (2) their views of corporate dependencies and impacts on ecosystem services; (3) related business risks and opportunities; and (4) viability of existing instruments and practices that can be employed in detecting and addressing business impacts and dependencies on ecosystem services. Through an inductive approach to the empirical findings, we refined a framework that holds operational value for developing company response strategies to ecosystem services impact/dependence assessment, ensuring that all issues are addressed comprehensively, and that related risks and opportunities are properly acknowledged.Peer reviewe

    Young stars and brown dwarfs surrounding Alnilam (eps Ori) and Mintaka (del Ori)

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    Aims: We look for new regions for the search of substellar objects. Methods: Two circular areas, 45 arcmin-radius each, centred on the young massive star systems Alnilam and Mintaka in the Orion Belt, have been explored. The regions are very young (less than 10 Ma), have low extinction, and are neighbours to sigma Orionis (~3 Ma), a young open cluster very rich in brown dwarfs and planetary-mass objects. We have used Virtual Observatory tools, the astro-photometric Tycho-2, DENIS and 2MASS catalogues, 10 control fields at similar galactic latitudes, and X-ray, mid-infrared and spectroscopic data from the literature. Results: We have compiled exhaustive lists of known young stars and new candidate members in the Ori OB1b association, and of fore- and background sources. A total of 136 stars display features of extreme youth, like early spectral types, lithium in absorption, or mid-infrared flux excess. Other two young brown dwarf and 289 star candidates have been identified from an optical/near-infrared colour-magnitude diagram. We list additional 74 known objects that might belong to the association. This catalogue can serve as an input for characterisation of the stellar and high-mass substellar populations in the Orion Belt. Finally, we have investigated the surface densities and radial distributions of young objects surrounding Alnilam and Mintaka, and compared them with those in the sigma Orionis cluster. We report a new open cluster centred on Mintaka. Conclusions: Both regions can be analogs to the sigma Orionis cluster, but more massive, more extended, slightly older, and less radially concentrated.Comment: Accepted for publication in A&A. It will be published on line in Sect. 14 (Catalogs and data). Tables in Appendix A will soon be available at the CD

    Comparison of 6q25 Breast Cancer Hits from Asian and European Genome Wide Association Studies in the Breast Cancer Association Consortium (BCAC)

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    Superintendency receipt dated August 20, 1859

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    Receipt of A Humphreys for Indian goods
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