55,310 research outputs found

    Inflation and Budget Deficit: What is the Relationship in Portugal?

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    The main causes of Portuguese inflation, based on annual data from 1954 to 1995, using the Johansen method, allows us to conclude that variation in Portuguese inflation is determined essentially by foreign inflation and by variation in the effective exchange rate of the Portuguese Escudo (PTE). In the long-term, the relationship between inflation rate and the growth rate of unit labour costs is almost unitary. However, the response of inflation change to the equilibrium error between inflation rate and changes in unit labour costs is slow and almost insignificant, while the response of unit labour costs to this disequilibrium is fast and significant, what suggests that the direction of causality is much more evident from the inflation rate on unit labour costs, than the reverse. The budget deficit as a percentage of GDP, are not significant in the short-term, in relation to variation in inflation as a dependent variable. However, it is significant in the relation to unit labour costs as a dependent variable, so we can have an indirect positive relation between inflation and lagged budget deficit.Inflation, Budget Deficit, Unit Roots, and Cointegration

    Stability of Closed Timelike Geodesics

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    The existence and stability under linear perturbations of closed timelike geodesics (CTGs) in Bonnor-Ward spacetime is studied in some detail. Regions where the CTG exist and are linearly stable are exhibited.Comment: 5 pages, REvTex, discussion added. PLA, in pres

    Reliability of the optimized perturbation theory in the 0-dimensional O(N)O(N) scalar field model

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    We address the reliability of the Optimized Perturbation Theory (OPT) in the context of the 0-dimensional O(N)O(N) scalar field model. The effective potential, the self-energy and the 1PI four-point Green's function for the model are computed using different optimization schemes and the results contrasted to the exact results for the model. Our results are also compared to those obtained with the 1/N1/N-expansion and with those from ordinary perturbation theory. The OPT results are shown to be stable even at large couplings and to have better convergence properties than the ones produced in the 1/N1/N-expansion. It is also shown that the principle of minimal sensitive optimization procedure used in conjunction with the OPT method tends to always produce better results, in particular when applied directly to the self-energy.Comment: 38 pages, 13 figures, v2 Physica A versio

    Modulation of near-field heat transfer between two gratings

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    We present a theoretical study of near-field heat transfer between two uniaxial anisotropic planar structures. We investigate how the distance and relative orientation (with respect to their optical axes) between the objects affect the heat flux. In particular, we show that by changing the angle between the optical axes it is possible in certain cases to modulate the net heat flux up to 90% at room temperature, and discuss possible applications of such a strong effect

    Changing the University System Management: a study of the Italian scenario

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    Over recent years, the Italian University System has been handling a phase of deep changes, which have had significant impact on its mission and on the way it operates. The most important of these changes have been to the organisation of universities, their recruitment procedures and in terms of improvements to the quality and efficiency of the university system itself. In this perspective, the objective of this research was to carry out a critical analysis of the process of change, with special reference to improving efficiency by making the transition from cash-based accounting to accrual accounting. In order to achieve this objective, the starting point was the legislation of reference that sets out the terms for the move to financial accrual accounting. A comparative analysis was then carried out at an international level, with the purpose of highlighting the strengths and weaknesses identified during the implementation of these new procedures within the public field. This was followed by an analysis of the details of the theory defining the accounting principles to be used in the process of preparing university’s financial statements. Finally, the study identified the main critical points relating to implementation of the new accounting system, offering, at the same time, several thoughts concerning possible subsequent analyses on this topic

    Extremum-entropy-based Heisenberg-like uncertainty relations

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    In this work we use the extremization method of various information-theoretic measures (Fisher information, Shannon entropy, Tsallis entropy) for dd-dimensional quantum systems, which complementary describe the spreading of the quantum states of natural systems. Under some given constraints, usually one or two radial expectation values, this variational method allows us to determine an extremum-entropy distribution, which is the \textit{least-biased} one to characterize the state among all those compatible with the known data. Then we use it, together with the spin-dependent uncertainty-like relations of Daubechies-Thakkar type, as a tool to obtain relationships between the position and momentum radial expectation values of the type rαkαpkf(k,α,q,N),q=2s+1\langle r^{\alpha}\rangle^{\frac{k}{\alpha}}\langle p^k\rangle\geq f(k,\alpha,q,N), q=2s+1, for dd-dimensional systems of NN fermions with spin ss. The resulting uncertainty-like products, which take into account both spatial and spin degrees of freedom of the fermionic constituents of the system, are shown to often improve the best corresponding relationships existing in the literature.Comment: Accepted for publication in Journal of Physics

    Cosmological solutions in generalized hybrid metric-Palatini gravity

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    We construct exact solutions representing a Friedmann-Lema\^itre-Robsertson-Walker (FLRW) universe in a generalized hybrid metric-Palatini theory. By writing the gravitational action in a scalar-tensor representation, the new solutions are obtained by either making an ansatz on the scale factor or on the effective potential. Among other relevant results, we show that it is possible to obtain exponentially expanding solutions for flat universes even when the cosmology is not purely vacuum. We then derive the classes of actions for the original theory which generate these solutions.Comment: 14 pages, 17 figure
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