16,755 research outputs found

    Contribution of simulation and gaming to natural resource management issues: An introduction

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    Nowadays, computer-mediated simulations and games are widely used in the field of natural resource management (NRM). They have proved to be useful for various purposes such as supporting decisionmaking processes and training. First, the specificities of the NRM research field are highlighted. Then, based on the analysis of the articles presented in this special issue of Simulation & Gaming, some key features related to the implementation of gaming in such a context are introduced. Finally, after reviewing the benefits of using simulation games in NRM, the authors stress the ethical issue of changing social relationships among stakeholders by playing a game with some of themGESTION DE L'ENVIRONNEMENT;RESSOURCE NATURELLE;SIMULATION;SOCIOLOGIE;JEU DE ROLE;BENEFITS;CONTEXT;COLLECTIVE POLICY DESIGN;DECISION MAKING;ETHICAL ISSUES;IMPLEMENTATION;NATURAL RESOURCE MANAGEMENT (NRM);SIMULATION GAMES;SOCIAL EMPOWERMENT;SOCIAL RELATIONSHIPS;SOCIOECOLOGICAL SYSTEMS;STAKEHOLDERS

    Relativistic Effects on the Appearance of a Clothed Black Hole

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    For an accretion disk around a black hole, the strong relativistic effects affect every aspect of the radiation from the disk, including its spectrum, light-curve, and image. This work investigates in detail how the images of a thin disk around a black hole will be distorted, and what the observer will see from different viewing angles and in different energy bands.Comment: 4 pages, 5 figures. Based on the poster presented at the Sixth Pacific Rim Conference on Stellar Astrophysics (Xi'an, China, July 11-17, 2002). Color versions of figures are given separatel

    A search for thermal X-ray signatures in Gamma-Ray Bursts I: Swift bursts with optical supernovae

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    The X-ray spectra of Gamma-Ray Bursts can generally be described by an absorbed power law. The landmark discovery of thermal X-ray emission in addition to the power law in the unusual GRB 060218, followed by a similar discovery in GRB 100316D, showed that during the first thousand seconds after trigger the soft X-ray spectra can be complex. Both the origin and prevalence of such spectral components still evade understanding, particularly after the discovery of thermal X-ray emission in the classical GRB 090618. Possibly most importantly, these three objects are all associated with optical supernovae, begging the question of whether the thermal X-ray components could be a result of the GRB-SN connection, possibly in the shock breakout. We therefore performed a search for blackbody components in the early Swift X-ray spectra of 11 GRBs that have or may have associated optical supernovae, accurately recovering the thermal components reported in the literature for GRBs 060218, 090618 and 100316D. We present the discovery of a cooling blackbody in GRB 101219B/SN2010ma, and in four further GRB-SNe we find an improvement in the fit with a blackbody which we deem possible blackbody candidates due to case-specific caveats. All the possible new blackbody components we report lie at the high end of the luminosity and radius distribution. GRB 101219B appears to bridge the gap between the low-luminosity and the classical GRB-SNe with thermal emission, and following the blackbody evolution we derive an expansion velocity for this source of order 0.4c. We discuss potential origins for the thermal X-ray emission in our sample, including a cocoon model which we find can accommodate the more extreme physical parameters implied by many of our model fits.Comment: 16 pages, 6 figures, accepted for MNRA

    Maritime tourism and terrorism: Customer perceptions of the potential terrorist threat to cruise shipping

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    Maritime terrorism is a neglected area of research in tourism, particularly the use of scenario planning to understand potential threats to the cruise industry. Since the events of 9/11, terrorism, and the threat of terrorism, has become a major concern within the tourism industry. This article analyses tourist perception of perceived terrorist threats given that many ships are American owned. Using the scenario analysis presented by Greenberg, Chalk, Willis, Khilko, and Ortiz, this study suggests that an attack on a cruise ship is a distinct possibility. Indeed, 44% of respondents questioned perceived the possibility of a terrorist attack on a cruise ship to be likely despite the fact that safety and security is seen by the industry as a 'hallmark' of cruising. Differences in attitude among potential passengers revealed a high level of confidence in the cruise ship companies. This finding is particularly marked among more experienced cruise ship passengers. However, this did not necessarily preclude the possibility of security measures being improved. All passengers appeared generally resigned to the fact that risk is associated with travel in the twenty-first century and welcomed any efforts by cruise shipping companies to improve safety and security. © 2012 © 2012 Taylor & Francis

    Understanding the magnetic resonance spectrum of nitrogen vacancy centers in an ensemble of randomly-oriented nanodiamonds

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    Nanodiamonds containing nitrogen vacancy (NV-) centers show promise for a number of emerging applications including targeted in vivo imaging and generating nuclear spin hyperpolarization for enhanced NMR spectroscopy and imaging. Here, we develop a detailed understanding of the magnetic resonance behavior of NV- centers in an ensemble of nanodiamonds with random crystal orientations. Two-dimensional optically detected magnetic resonance spectroscopy reveals the distribution of energy levels, spin populations, and transition probabilities that give rise to a complex spectrum. We identify overtone transitions that are inherently insensitive to crystal orientation and give well-defined transition frequencies that access the entire nanodiamond ensemble. These transitions may be harnessed for high-resolution imaging and generation of nuclear spin hyperpolarization. The data are well described by numerical simulations from the zero- to high-field regimes, including the intermediate regime of maximum complexity. We evaluate the prospects of nanodiamond ensembles specifically for nuclear hyperpolarization and show that frequency-swept dynamic nuclear polarization may transfer a large amount of the NV- center's hyperpolarization to nuclear spins by sweeping over a small region of its spectrum.Comment: 6 pages, 5 figure

    New Einstein-Sasaki Spaces in Five and Higher Dimensions

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    We obtain infinite classes of new Einstein-Sasaki metrics on complete and non-singular manifolds. They arise, after Euclideanisation, from BPS limits of the rotating Kerr-de Sitter black hole metrics. The new Einstein-Sasaki spaces L^{p,q,r} in five dimensions have cohomogeneity 2, and U(1) x U(1) x U(1) isometry group. They are topologically S^2 x S^3. Their AdS/CFT duals will describe quiver theories on the four-dimensional boundary of AdS_5. We also obtain new Einstein-Sasaki spaces of cohomogeneity n in all odd dimensions D=2n+1 \ge 5, with U(1)^{n+1} isometry.Comment: Revtex, 4 pages, metric regularity conditions are further refine

    Hybrid meson decay from the lattice

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    We discuss the allowed decays of a hybrid meson in the heavy quark limit. We deduce that an important decay will be into a heavy quark non-hybrid state and a light quark meson, in other words, the de-excitation of an excited gluonic string by emission of a light quark-antiquark pair. We discuss the study of hadronic decays from the lattice in the heavy quark limit and apply this approach to explore the transitions from a spin-exotic hybrid to χbη\chi_b \eta and χbS\chi_b S where SS is a scalar meson. We obtain a signal for the transition emitting a scalar meson and we discuss the phenomenological implications.Comment: 18 pages, LATEX, 3 ps figure

    Rotating Black Holes in Higher Dimensions with a Cosmological Constant

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    We present the metric for a rotating black hole with a cosmological constant and with arbitrary angular momenta in all higher dimensions. The metric is given in both Kerr-Schild and Boyer-Lindquist form. In the Euclidean-signature case, we also obtain smooth compact Einstein spaces on associated S^{D-2} bundles over S^2, infinitely many for each odd D\ge 5. Applications to string theory and M-theory are indicated.Comment: 8 pages, Latex. Short version, with more compact notation, of hep-th/0404008. To appear in Phys. Rev. Let
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