5,189 research outputs found

    Socioeconomic effects of protected areas in Spain across spatial scales and protection levels

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    Impacts of the legal designation of protected areas (PAs) may have contrasting implications for different stakeholders, and at different spatial scales. In this study, we analysed the organisational perception on the socioeconomic effects of PA designation from all sectors of activity in Spain, accounting for PAs’ legal stringency. A semi-structured questionnaire was administered to 68 organisations at national, regional (Andalusia) and local scales (two municipalities in the Almeria province, Andalusia) through an online survey. Local stakeholders and the primary, secondary and tertiary sectors were most concerned about the social and economic impacts of PAs designation on their organisations. By contrast, organisations at the national or regional scales together with public institutions, the quaternary sector and other miscellaneous stakeholders perceived predominantly positive effects. Only national organisations perceived an increase in local social and economic effects from the designation of legally stringent PAs with regard to multiple-use PAs

    Revisiting the optical PTPT-symmetric dimer

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    Optics has proved a fertile ground for the experimental simulation of quantum mechanics. Most recently, optical realizations of PT\mathcal{PT}-symmetric quantum mechanics have been shown, both theoretically and experimentally, opening the door to international efforts aiming at the design of practical optical devices exploiting this symmetry. Here, we focus on the optical PT\mathcal{PT}-symmetric dimer, a two-waveguide coupler were the materials show symmetric effective gain and loss, and provide a review of the linear and nonlinear optical realizations from a symmetry based point of view. We go beyond a simple review of the literature and show that the dimer is just the smallest of a class of planar NN-waveguide couplers that are the optical realization of Lorentz group in 2+1 dimensions. Furthermore, we provide a formulation to describe light propagation through waveguide couplers described by non-Hermitian mode coupling matrices based on a non-Hermitian generalization of Ehrenfest theorem.Comment: 25 pages, 12 figure

    Deep into the Water Fountains: The case of IRAS 18043-2116

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    (Abridged) The formation of large-scale (hundreds to few thousands of AU) bipolar structures in the circumstellar envelopes (CSEs) of post-Asymptotic Giant Branch (post-AGB) stars is poorly understood. The shape of these structures, traced by emission from fast molecular outflows, suggests that the dynamics at the innermost regions of these CSEs does not depend only on the energy of the radiation field of the central star. Deep into the Water Fountains is an observational project based on the results of programs carried out with three telescope facilities: The Karl G. Jansky Very Large Array (JVLA), The Australia Telescope Compact Array (ATCA), and the Very Large Telescope (SINFONI-VLT). Here we report the results of the observations towards the WF nebula IRAS 18043-2116: Detection of radio continuum emission in the frequency range 1.5GHz - 8.0GHz; H2_{2}O maser spectral features and radio continuum emission detected at 22GHz, and H2_{2} ro-vibrational emission lines detected at the near infrared. The high-velocity H2_{2}O maser spectral features, and the shock-excited H2_{2} emission detected could be produced in molecular layers which are swept up as a consequence of the propagation of a jet-driven wind. Using the derived H2_{2} column density, we estimated a molecular mass-loss rate of the order of 10910^{-9}M_{\odot}yr1^{-1}. On the other hand, if the radio continuum flux detected is generated as a consequence of the propagation of a thermal radio jet, the mass-loss rate associated to the outflowing ionized material is of the order of 105^{-5}M_{\odot}yr1^{-1}. The presence of a rotating disk could be a plausible explanation for the mass-loss rates estimated.Comment: 10 pages, 5 figures. Accepted for publication in A&

    Exchange operator formalism for N-body spin models with near-neighbors interactions

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    We present a detailed analysis of the spin models with near-neighbors interactions constructed in our previous paper [Phys. Lett. B 605 (2005) 214] by a suitable generalization of the exchange operator formalism. We provide a complete description of a certain flag of finite-dimensional spaces of spin functions preserved by the Hamiltonian of each model. By explicitly diagonalizing the Hamiltonian in the latter spaces, we compute several infinite families of eigenfunctions of the above models in closed form in terms of generalized Laguerre and Jacobi polynomials.Comment: RevTeX, 31 pages, no figures; important additional conten
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