5,131 research outputs found

    Experiments on the effectiveness of marketing communications tactics to support ‘unappealing’ animals

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    This study was designed for investigating how effective different marketing communications tactics are at influencing donations to animal conservation campaigns featuring ‘unappealing’ (non-flagship) species. Experiments were executed to evaluate the effectiveness of celebrity endorsements, anthropomorphism, message framing, and personal incentives in fictitious animal conservation adverts. Results showed that urgent message tone was not successful at gaining support for non-flagship campaigns but combining anthropomorphism with positive message did increase support for nonflagship causes. Celebrity endorsements were shown to be successful at influencing willingness to donate, provided that the celebrity is highly credible in the world of animal conservation. Offering personal incentives to influence donations achieved its purpose when used in campaigns featuring ‘popular’ animals, but it was not a successful marketing tactic when used to promote ‘undesirable’ animals. Interestingly, the results revealed that participants were strongly influenced to donate to a non-flagship campaign when they believed that it would result in wider environmental benefits that would also be beneficial to humans. Overall, a participant’s prior knowledge or preference for a specific species had a great influence over donation choice. However, this study has revealed that through effective marketing participants can be swayed to support ‘undesirable’ animals instead of typically ‘preferred’ specie

    Quantitative Photo-acoustic Tomography with Partial Data

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    Photo-acoustic tomography is a newly developed hybrid imaging modality that combines a high-resolution modality with a high-contrast modality. We analyze the reconstruction of diffusion and absorption parameters in an elliptic equation and improve an earlier result of Bal and Uhlmann to the partial date case. We show that the reconstruction can be uniquely determined by the knowledge of 4 internal data based on well-chosen partial boundary conditions. Stability of this reconstruction is ensured if a convexity condition is satisfied. Similar stability result is obtained without this geometric constraint if 4n well-chosen partial boundary conditions are available, where nn is the spatial dimension. The set of well-chosen boundary measurements is characterized by some complex geometric optics (CGO) solutions vanishing on a part of the boundary.Comment: arXiv admin note: text overlap with arXiv:0910.250

    Simulating the collapse transition of a two-dimensional semiflexible lattice polymer

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    It has been revealed by mean-field theories and computer simulations that the nature of the collapse transition of a polymer is influenced by its bending stiffness ϵb\epsilon_{\rm b}. In two dimensions, a recent analytical work demonstrated that the collapse transition of a partially directed lattice polymer is always first-order as long as ϵb\epsilon_{\rm b} is positive [H. Zhou {\em et al.}, Phys. Rev. Lett. {\bf 97}, 158302 (2006)]. Here we employ Monte Carlo simulation to investigate systematically the effect of bending stiffness on the static properties of a 2D lattice polymer. The system's phase-diagram at zero force is obtained. Depending on ϵb\epsilon_{\rm b} and the temperature TT, the polymer can be in one of three phases: crystal, disordered globule, or swollen coil. The crystal-globule transition is discontinuous, the globule-coil transition is continuous. At moderate or high values of ϵb\epsilon_{\rm b} the intermediate globular phase disappears and the polymer has only a discontinuous crystal-coil transition. When an external force is applied, the force-induced collapse transition will either be continuous or discontinuous, depending on whether the polymer is originally in the globular or the crystal phase at zero force. The simulation results also demonstrate an interesting scaling behavior of the polymer at the force-induced globule-coil transition.Comment: 16 page

    Quantum Chaos of Bogoliubov Waves for a Bose-Einstein Condensate in Stadium Billiards

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    We investigate the possibility of quantum (or wave) chaos for the Bogoliubov excitations of a Bose-Einstein condensate in billiards. Because of the mean field interaction in the condensate, the Bogoliubov excitations are very different from the single particle excitations in a non-interacting system. Nevertheless, we predict that the statistical distribution of level spacings is unchanged by mapping the non-Hermitian Bogoliubov operator to a real symmetric matrix. We numerically test our prediction by using a phase shift method for calculating the excitation energies.Comment: minor change, 4 pages, 4 figures, to appear in Phys. Rev. Let

    Controlled Generation of Dark Solitons with Phase Imprinting

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    The generation of dark solitons in Bose-Einstein condensates with phase imprinting is studied by mapping it into the classic problem of a damped driven pendulum. We provide simple but powerful schemes of designing the phase imprint for various desired outcomes. We derive a formula for the number of dark solitons generated by a given phase step, and also obtain results which explain experimental observations.Comment: 4pages, 4 figure

    Transition to Instability in a Kicked Bose-Einstein Condensate

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    A periodically kicked ring of a Bose-Einstein condensate is considered as a nonlinear generalization of the quantum kicked rotor. For weak interactions between atoms, periodic motion (anti-resonance) becomes quasiperiodic (quantum beating) but remains stable. There exists a critical strength of interactions beyond which quasiperiodic motion becomes chaotic, resulting in an instability of the condensate manifested by exponential growth in the number of noncondensed atoms. Similar behavior is observed for dynamically localized states (essentially quasiperiodic motions), where stability remains for weak interactions but is destroyed by strong interactions.Comment: 4 pages, 6 figs. A new affiliation is added. Accepted by Phys. Rev. Let

    Energy-momentum for Randall-Sundrum models

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    We investigate the conservation law of energy-momentum for Randall-Sundrum models by the general displacement transform. The energy-momentum current has a superpotential and are therefore identically conserved. It is shown that for Randall-Sundrum solution, the momentum vanishes and most of the bulk energy is localized near the Planck brane. The energy density is ϵ=ϵ0e−3k∣y∣\epsilon = \epsilon_0 e^{-3k \mid y \mid}.Comment: 13 pages, no figures, v4: introduction and new conclusion added, v5: 11 pages, title changed and references added, accepted by Mod. Phys. Lett.

    Reconstruction of Gas Temperature and Density Profiles of the Galaxy Cluster RX J1347.5-1145

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    We use observations of Sunyaev-Zel'dovich effect and X-ray surface brightness to reconstruct the radial profiles of gas temperature and density under the assumption of a spherically symmetric distribution of the gas. The method of reconstruction, first raised by Silk & White, depends directly on the observations of the Sunyaev-Zel'dovich effect and the X-ray surface brightness, without involving additional assumptions such as the equation of state of the gas or the conditions of hydrostatic equilibrium. We applied this method to the cluster RX J1347.5-1145, which has both the Sunyaev-Zel'dovich effect and X-ray observations with relative high precision. It is shown that it will be an effective method to obtain the gas distribution in galaxy clusters. Statistical errors of the derived temperature and density profiles of gas were estimated according to the observational uncertainties.Comment: 6 pages, 1 figure. The published version, 2008, Chin. J. Astron. Astrophys., 8, 67

    Vesicles in solutions of hard rods

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    The surface free energy of ideal hard rods near curved hard surfaces is determined to second order in curvature for surfaces of general shape. In accordance with previous results for spherical and cylindrical surfaces it is found that this quantity is non-analytical when one of the principal curvatures changes signs. This prohibits writing it in the common Helfrich form. It is shown that the non-analytical terms are the same for any aspect ratio of the rods. These results are used to find the equilibrium shape of vesicles immersed in solutions of rod-like (colloidal) particles. The presence of the particles induces a change in the equilibrium shape and to a shift of the prolate-oblate transition in the vesicle phase diagram, which are calculated within the framework of the spontaneous curvature model. As a consequence of the special form of the energy contribution due to the rods these changes cannot be accounted for by a simple rescaling of the elastic constants of the vesicle as for solutions of spherical colloids or polymers.Comment: 11 pages, 7 figures, submitted to Phys. Rev.

    Comments on Noncommutative ADHM Construction

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    We extend the method of matrix partition to obtain explicitly the gauge field for noncommutative ADHM construction in some general cases. As an application of this method we apply it to the U(2) 2-instanton and get explicit result for the gauge fields in the coincident instanton limit. We also easily apply it to the noncommutative 't Hooft instantons in the appendix.Comment: 17 pages, LaTeX; an appendix added, typos corrected, refs adde
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