1,508 research outputs found

    General Connectivity Distribution Functions for Growing Networks with Preferential Attachment of Fractional Power

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    We study the general connectivity distribution functions for growing networks with preferential attachment of fractional power, Πikα\Pi_{i} \propto k^{\alpha}, using the Simon's method. We first show that the heart of the previously known methods of the rate equations for the connectivity distribution functions is nothing but the Simon's method for word problem. Secondly, we show that the case of fractional α\alpha the ZZ-transformation of the rate equation provides a fractional differential equation of new type, which coincides with that for PA with linear power, when α=1\alpha = 1. We show that to solve such a fractional differential equation we need define a transidental function Υ(a,s,c;z)\Upsilon (a,s,c;z) that we call {\it upsilon function}. Most of all previously known results are obtained consistently in the frame work of a unified theory.Comment: 10 page

    Local expert experiences and perceptions of environmentally induced migration from Bangladesh to India

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    This study investigates local expert perceptions of the role of environmental factors, especially in terms of contemporary climate change, in population movements from Bangladesh to India. The aim is to delve into locally held understandings of the phenomenon and to gain a better understanding of these migration processes, which are actively intertwined with local experiences. Both Indian and Bangladeshi experts were interviewed using semi-structured, in-depth interviews in order to explore insights from locally held perceptions and understandings of contextual factors. In total, 10 Bangladeshi and 15 Indian experts were interviewed, covering different disciplines, sectors, regions and job types, together providing a more complete and grounded picture of views of environmentally induced migration in Bangladesh and India. The results show that climate change is perceived by local experts as one of the key factors influencing migration in Bangladesh, both internally and externally. The interviewees, however, placed environmentally induced migration in a broader context of labour and economic migration. In particular, migration for environmental reasons in Bangladesh was evident long before the emergence of climate change as an issue. According to the interviewed experts, this does not preclude increased environmentally induced migration within and from Bangladesh in the future, but its analyses ought to be placed in historical and economical contexts

    Nonadiabatic coherent evolution of two-level systems under spontaneous decay

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    In this paper we extend current perspectives in engineering reservoirs by producing a time-dependent master equation leading to a nonstationary superposition equilibrium state that can be nonadiabatically controlled by the system-reservoir parameters. Working with an ion trapped inside a nonindeal cavity we first engineer effective Hamiltonians that couple the electronic states of the ion with the cavity mode. Subsequently, two classes of decoherence-free evolution of the superposition of the ground and decaying excited levels are achieved: those with time-dependent azimuthal or polar angle. As an application, we generalise the purpose of an earlier study [Phys. Rev. Lett. 96, 150403 (2006)], showing how to observe the geometric phases acquired by the protected nonstationary states even under a nonadiabatic evolution.Comment: 5 pages, no figure

    Developing a structured and strategically focused performance assessment system

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    The number and adequacy of Performance-Indicators (PIs) for organisational purposes are core to the success of organisations and a major concern to the sponsor of this research. This assignment developed a procedure to improve a firm’s performance assessment system, by identifying two key-PIs out of 28 initial ones, and by setting criteria and their relative importance to validate and rank the adequacy and the right number of operational metrics. The Analytical-Hierarchy-Process was used with a synthesis-method to treat data coming from the management inquiries. Although organisational alignment has been achieved, business processes should also be targeted and PIs continuously revised.info:eu-repo/semantics/publishedVersio

    Anisotropic diffusion in continuum relaxation of stepped crystal surfaces

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    We study the continuum limit in 2+1 dimensions of nanoscale anisotropic diffusion processes on crystal surfaces relaxing to become flat below roughening. Our main result is a continuum law for the surface flux in terms of a new continuum-scale tensor mobility. The starting point is the Burton, Cabrera and Frank (BCF) theory, which offers a discrete scheme for atomic steps whose motion drives surface evolution. Our derivation is based on the separation of local space variables into fast and slow. The model includes: (i) anisotropic diffusion of adsorbed atoms (adatoms) on terraces separating steps; (ii) diffusion of atoms along step edges; and (iii) attachment-detachment of atoms at step edges. We derive a parabolic fourth-order, fully nonlinear partial differential equation (PDE) for the continuum surface height profile. An ingredient of this PDE is the surface mobility for the adatom flux, which is a nontrivial extension of the tensor mobility for isotropic terrace diffusion derived previously by Margetis and Kohn. Approximate, separable solutions of the PDE are discussed.Comment: 14 pages, 1 figur

    Pade approximation of the S-matrix as a way of locating quantum resonances and bound states

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    It is shown that the spectral points (bound states and resonances) generated by a central potential of a single-channel problem, can be found using rational parametrization of the S-matrix. To achieve this, one only needs values of the S-matrix along the real positive energy axis. No calculations of the S-matrix at complex energies or a complex rotation are necessary. The proposed method is therefore universal in that it is applicable to any potential (local, non-local, discontinuous, etc.) provided that there is a way of obtaining the S-matrix (or scattering phase-shifts) at real collision energies. Besides this, combined with any method that extracts the phase-shifts from the scattering data, the proposed rational parametrization technique would be able to do the spectral analysis using the experimental data.Comment: 20 pages, 6 figure

    Avaliação da resistência a Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) e Euxesta sp. (Diptera: Otitidae) em linhagens de milho-doce.

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    Sixteen tines of sweet com were evaluated for resistance to Helicoverpa zea (Boddie) and Euxesta sp. Artificial and natural infestation of H. zea (Boddie) were used. The tines DCOl and DC03 were resistant to both pests. No difference was observed between artificial and natural infestation
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