11,359 research outputs found

    Recovery operators, paraconsistency and duality

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    There are two foundational, but not fully developed, ideas in paraconsistency, namely, the duality between paraconsistent and intuitionistic paradigms, and the introduction of logical operators that express meta-logical notions in the object language. The aim of this paper is to show how these two ideas can be adequately accomplished by the Logics of Formal Inconsistency (LFIs) and by the Logics of Formal Undeterminedness (LFUs). LFIs recover the validity of the principle of explosion in a paraconsistent scenario, while LFUs recover the validity of the principle of excluded middle in a paracomplete scenario. We introduce definitions of duality between inference rules and connectives that allow comparing rules and connectives that belong to different logics. Two formal systems are studied, the logics mbC and mbD, that display the duality between paraconsistency and paracompleteness as a duality between inference rules added to a common core– in the case studied here, this common core is classical positive propositional logic (CPL + ). The logics mbC and mbD are equipped with recovery operators that restore classical logic for, respectively, consistent and determined propositions. These two logics are then combined obtaining a pair of logics of formal inconsistency and undeterminedness (LFIUs), namely, mbCD and mbCDE. The logic mbCDE exhibits some nice duality properties. Besides, it is simultaneously paraconsistent and paracomplete, and able to recover the principles of excluded middle and explosion at once. The last sections offer an algebraic account for such logics by adapting the swap-structures semantics framework of the LFIs the LFUs. This semantics highlights some subtle aspects of these logics, and allows us to prove decidability by means of finite non-deterministic matrices

    Scalar and higher even spin glueball masses from an anomalous modified holographic model

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    In this work, within an anomalous modified holographic softwall model, we calculate analytically the masses of the scalar glueball with its radial excitations and higher even glueball spin states, with P=C=+1P=C=+1, from a single mass equation. Using this approach we achieved an unified treatment for both scalar and high even spin glueballs masses. Furthermore, we also obtain the Regge trajectory associated with the pomeron compatible with other approaches.Comment: V4: 14 pages, 3 tables, 1 figure. Text improved. New references included. Typos corrected. Results slightly modified due to the improvement of the statistical analysis. This version matches the published one in EP

    Towards a low carbon economy in the Amazon: the role of land-use policies

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    Climate change, rising oil prices and the global financial crisis has put sustainability and ‘green growth’ of the economy on the political agenda. While the transition towards a “low carbon” economy in developed countries like in the European Union should mainly be found in renewable energy production, developing countries like Brazil face with high land use emissions which will further rise in the coming decades without proper policy instruments. Deforestation and cattle production are the main sources of land use emissions in Brazil and we expect that these emissions will further rise with liberalisation of agricultural trade. A transition towards a “low carbon” economy in Brazil thus calls for appropriate, and effective land-use policies. Agricultural intensification on one hand can meet the world demand for soy and beef. For example we calculate that increasing the meat content of cattle can reduce emissions from deforestation up to 30%, but intensification may also accelerate further deforestation of Cerrado and Amazon forests. In order to avoid such additional deforestation, large areas of degraded lands have to be taken back into production, which requires large agricultural investments. In addition, (new) economic instruments, monitoring, law enforcement and appropriate conservation policies are also needed to halt further deforestation and biodiversity loss. The recently amended change of the Forest Code policy, for example, is expected to accelerate deforestation further, thus making more difficult to reach mitigation targets for the Brazilian State

    Holographic Description of Chiral Symmetry Breaking in a Magnetic Field in 2+1 Dimensions with an Improved Dilaton

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    We consider a holographic description of the chiral symmetry breaking in an external magnetic field in (2+1) (2+1) -dimensional gauge theories from the softwall model using an improved dilaton field profile given by Ί(z)=−kz2+(k+k1)z2tanh⁥(k2z2)\Phi(z) = - kz^2 + (k+k_1)z^2\tanh (k_{2}z^2). We find inverse magnetic catalysis for BBcBB_c, where BcB_c is the pseudocritical magnetic field. The transition between these two regimes is a crossover and occurs at B=BcB=B_c, which depends on the fermion mass and temperature. We also find spontaneous chiral symmetry breaking (the chiral condensate σ=Ìž0\sigma \not=0) at T=0T=0 in the chiral limit (mq→0m_q\to 0) and chiral symmetry restoration for finite temperatures. We observe that changing the kk parameter of the dilaton profile only affects the overall scales of the system such as BcB_c and σ\sigma. For instance, by increasing kk one sees an increase of BcB_c and σ\sigma. This suggests that increasing the parameters k1k_1 and k2k_2 will decrease the values of BcB_c and σ\sigma.Comment: V2: 13 pages, 10 figures. New figure added. Text improved. Typos corrected. New references added. Results unchanged. This version matches the published one in EP

    Has core inflation been doing a good job in Brazil?

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    This paper assesses the performance of the core inflation measures calculated by the Brazilian Central Bank (BCB). The evidence shows that they do not meet some key statistical criteria that a good core inflation should have: unbiasedness and the ability to forecast inflation. That performance stems, to a large extent, from the lack of a well-grounded statistical and economical basis behind them. Three new measures are built and assessed using the same criteria. The evidence shows that their behaviour is more in accordance to what the theory claims. However, they still lack the ability to help forecasting inflation. Hence both the BCB and the market should use core inflation cautiously.Core inflation; inflation; supply shocks; relative prices; volatility
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