21,277 research outputs found

    Impact of Uncertainties in Hadron Production on Air-Shower Predictions

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    At high energy, cosmic rays can only be studied by measuring the extensive air showers they produce in the atmosphere of the Earth. Although the main features of air showers can be understood within a simple model of successive interactions, detailed simulations and a realistic description of particle production are needed to calculate observables relevant to air shower experiments. Currently hadronic interaction models are the main source of uncertainty of such simulations. We will study the effect of using different hadronic models available in CORSIKA and CONEX on extensive air shower predictions.Comment: 12 pages, 6 figures, to appear in the proceedings of International Conference on Interconnection between High Energy Physics and Astroparticle Physics: From Colliders to Cosmic Rays, Prague, Czech Republic, 7-13 Sep 200

    Controlled exchange interaction for quantum logic operations with spin qubits in coupled quantum dots

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    A two-electron system confined in two coupled semiconductor quantum dots is investigated as a candidate for performing quantum logic operations on spin qubits. We study different processes of swapping the electron spins by controlled switching on/off the exchange interaction. The resulting spin swap corresponds to an elementary operation in quantum information processing. We perform a direct time evolution simulations of the time-dependent Schroedinger equation. Our results show that -- in order to obtain the full interchange of spins -- the exchange interaction should change smoothly in time. The presence of jumps and spikes in the corresponding time characteristics leads to a considerable increase of the spin swap time. We propose several mechanisms to modify the exchange interaction by changing the confinement potential profile and discuss their advantages and disadvantages

    Reply on the comment on the paper "Superconducting transition in Nb nanowires fabricated using focused ion beam"

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    In this communication we present our response to the recent comment of A. Engel regarding our paper on FIB- fabricated Nb nanowires (see Vol. 20 (2009) Pag. 465302). After further analysis and additional experimental evidence, we conclude that our interpretation of the experimental results in light of QPS theory is still valid when compared with the alternative proximity-based model as proposed by A. Engel.Comment: 3 pages, 1 figure, accepted by Nanotechnolog

    Comment: Superconducting transition in Nb nanowires fabricated using focused ion beam

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    In a recent paper Tettamanzi et al (2009 Nanotechnology \bf{20} 465302) describe the fabrication of superconducting Nb nanowires using a focused ion beam. They interpret their conductivity data in the framework of thermal and quantum phase slips below TcT_c. In the following we will argue that their analysis is inappropriate and incomplete, leading to contradictory results. Instead, we propose an interpretation of the data within a SN proximity model.Comment: 3 pages, 1 figure accepted in Nanotechnolog

    Local correlation functional for electrons in two dimensions

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    We derive a local approximation for the correlation energy in two-dimensional electronic systems. In the derivation we follow the scheme originally developed by Colle and Salvetti for three dimensions, and consider a Gaussian approximation for the pair density. Then, we introduce an ad-hoc modification which better accounts for both the long-range correlation, and the kinetic-energy contribution to the correlation energy. The resulting functional is local, and depends parametrically on the number of electrons in the system. We apply this functional to the homogeneous electron gas and to a set of two-dimensional quantum dots covering a wide range of electron densities and thus various amounts of correlation. In all test cases we find an excellent agreement between our results and the exact correlation energies. Our correlation functional has a form that is simple and straightforward to implement, but broadly outperforms the commonly used local-density approximation

    Developing guidelines for the human-wildlife interactions in conservation translocations

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    Workshop: Conservation translocation is a widely used management intervention to restore locally extinct or augment severely depleted species. Human dimension issues that influence the achievement of these aims are encountered at five different stages of the project life cycle: 1) Planning, 2) Initiation, 3) Implementation, 4) Ending, and 5) Post-exit stage. Overlooking such dimension may jeopardise the success of the project. Understanding and addressing human-wildlife interaction issues improve community involvement, peers’ acceptance and the support from various interest groups. In this workshop we propose to discuss participants’ experiences in human dimensions related to each of the 5 stages of a project’s life cycle.  Discussions aims to expand on findings from the IUCN/SSC CTSG HWIWG 2022 Guidelines to Facilitate Human-Wildlife Interactions in Conservation Translocations, to identify best practice and key issues for each stage to inform planning and promote wildlife conservation, collaboration amongst groups and coexistence
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