268,750 research outputs found

    Diffusion of mobile phones in Portugal: unexpected success?

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    This paper begins with a somewhat paradoxical situation: Portugal is one of the less innovative countries within the European Union by most innovation indicators but, simultaneously, it is a leading country in the diffusion of mobile phones. The remarkable evolution of the mobile telecommunications sector over the last 15 years turns the issue a little more intriguing. This paper addresses the diffusion of mobile phones in Portugal and focuses particularly on the take-off stage, which signalled a sudden change in the pattern of diffusion. The introduction of an innovation – prepaid cards – explains most of the change in the diffusion curve occurred around 1996 and the subsequent increase in the penetration rate. Prior known research has not considered pre-paid cards an important determinant of mobile phone diffusion, but pre-paid services had an enormous impact on the rate of adoption of mobile phones in many countries and it is the major take-off determinant of mobile phone diffusion in Portugal. The time lag between the launching of this innovation in Portugal and its adoption by other EU countries explains why Portugal not just caught up with the EU average mobile phone penetration rate around 1996, but moved ahead of it from then on

    On the Nature of Hinge Commitments

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    This is a critical commentary on Pritchard's book Epistemic Angst. In Section 2, I present the closure-based radical skeptical paradox. Then in Section 3, I sketch Pritchard’s undercutting response to this paradox. Finally, in Section 4, I put forward two concerns about Pritchard’s response and I also propose a reading of hinge commitments, the ability reading, that might put some pressure on Pritchard’s own reading of these commitments

    The violence of criminalisation

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    Hyperbolicity, transitivity and the two-sided limit shadowing property

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    We explore the notion of two-sided limit shadowing property introduced by Pilyugin \cite{P1}. Indeed, we characterize the C1C^1-interior of the set of diffeomorphisms with such a property on closed manifolds as the set of transitive Anosov diffeomorphisms. As a consequence we obtain that all codimention-one Anosov diffeomorphisms have the two-sided limit shadowing property. We also prove that every diffeomorphism ff with such a property on a closed manifold has neither sinks nor sources and is transitive Anosov (in the Axiom A case). In particular, no Morse-Smale diffeomorphism have the two-sided limit shadowing property. Finally, we prove that C1C^1-generic diffeomorphisms on closed manifolds with the two-sided limit shadowing property are transitive Anosov. All these results allow us to reduce the well-known conjecture about the transitivity of Anosov diffeomorphisms on closed manifolds to prove that the set of diffeomorphisms with the two-sided limit shadowing property coincides with the set of Anosov diffeomorphisms.Comment: 10 page

    On a new species of intertidal water strider from Brazil (Hemiptera, Gerromorpha, Mesoveliidae)

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    This paper deals with the description of a new species of Hemiptera, Gerromorpha, Mesoveliidae, from Marudá, State of Pará, Brazil - Darwinivelia polhemi n. sp. Illustrations of habitus, genitalia and other morphological parts are also included
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