Non-Gaussian statistics, maxwellian derivation and stellar polytropes

In this letter we discuss the Non-gaussian statistics considering two aspects. In the first, we show that the Maxwell's first derivation of the stationary distribution function for a dilute gas can be extended in the context of Kaniadakis statistics. The second one, by investigating the stellar system, we study the Kaniadakis analytical relation between the entropic parameter $\kappa$ and stellar polytrope index $n$. We compare also the Kaniadakis relation $n=n(\kappa)$ with $n=n(q)$ proposed in the Tsallis framework.Comment: 10 pages, 1 figur

Energy savings via foreign direct investment? : empirical evidence from Portugal

This study runs a cointegration analysis on annual data from 1980 to 2007 to investigate the relationship between primary energy consumption, economic growth and net inflows of foreign direct investment with the Engle and Granger method, Stock-Watson dynamic ordinary least squares (DOLS), the bounds testing approach to cointegration and error correction modelling. The empirical results suggest that there is a stable long run linear cointegration relationship between these three variables. While income has a large and positive influence on energy consumption, the results point to a small but negative effect of foreign direct investment (FDI) on energy consumption. As for the short-run relationship among the series, the estimation and inference in the autoregressive distributed lag error correction model (ARDL) further confirm this link. These findings have important policy implications, since the promotion of appropriate structural policies aiming at attracting foreign investment can induce energy conservation without obstructing economic growth

Generalized nonuniform dichotomies and local stable manifolds

We establish the existence of local stable manifolds for semiflows generated by nonlinear perturbations of nonautonomous ordinary linear differential equations in Banach spaces, assuming the existence of a general type of nonuniform dichotomy for the evolution operator that contains the nonuniform exponential and polynomial dichotomies as a very particular case. The family of dichotomies considered allow situations for which the classical Lyapunov exponents are zero. Additionally, we give new examples of application of our stable manifold theorem and study the behavior of the dynamics under perturbations.Comment: 18 pages. New version with minor corrections and an additional theorem and an additional exampl

Generalized Chaplygin Gas Model: Dark Energy - Dark Matter Unification and CMBR Constraints

The generalized Chaplygin gas (GCG) model allows for an unified description of the recent accelerated expansion of the Universe and the evolution of energy density perturbations. This dark energy - dark matter unification is achieved through an exotic background fluid whose equation of state is given by $p = - A/\rho^{\alpha}$, where $A$ is a positive constant and $0 < \alpha \le 1$. Stringent constraints on the model parameters can be obtained from recent WMAP and BOOMERanG bounds on the locations of the first few peaks and troughs of the Cosmic Microwave Background Radiation (CMBR) power spectrum as well as SNe Ia data.Comment: 9 pages, 2 figures; essay selected for an honorable mention by the Gravity Research Foundation, 200

Cointegration and Asymmetric Adjustment between Output and Unemployment: an Application to the U.S. Economy

This paper focuses on the properties of the adjustment between the real output and the unemployment rate for the U.S. economy in the period from 1975 to 2006. It starts by checking the order of integration of the two series and then tests for the presence of asymmetry in the Okun’s law relationship through a cyclical equation, a first differences equation and an ADL(p,q). Using the threshold cointegration approach this study also accounts for the possible existence of a long-run equilibrium relationship and it is ability to test for the asymmetric adjustment hypothesis. It is found that Okun’s coefficient ranges between -0.41 and -0.59, being the latter estimated by the cointegrating equation. Furthermore, the unemployment rate behaves differently along the business cycle and increases faster in recessions than it recovers in expansions. A long-run equilibrium relationship is established where adjustment is made asymmetrically. Positive deviations away from equilibrium are corrected slightly faster than negative ones. Our explanation concerns the higher speed of flows within the labor market during a recession than during an expansion which may also be related to the existence of nominal rigidities in the US economy that causes imperfectly flexible prices.Okun’s Law, Threshold Cointegration, Asymmetric Adjustment, Monte Carlo Simulations, U.S. Economy

Counting solutions from finite samplings

We formulate the solution counting problem within the framework of inverse Ising problem and use fast belief propagation equations to estimate the entropy whose value provides an estimate on the true one. We test this idea on both diluted models (random 2-SAT and 3-SAT problems) and fully-connected model (binary perceptron), and show that when the constraint density is small, this estimate can be very close to the true value. The information stored by the salamander retina under the natural movie stimuli can also be estimated and our result is consistent with that obtained by Monte Carlo method. Of particular significance is sizes of other metastable states for this real neuronal network are predicted.Comment: 9 pages, 4 figures and 1 table, further discussions adde

Recurrent Parotiditis the First Manifestation of Systemic Lupus Erythematosus

Neste artigo apresenta-se o caso clínico de uma doente de 45 anos de idade com tumefacção recorrente das parótidas, que, após quatro anos de evolução, é internada por febre vespertina, sudorese nocturna, toracalgia esquerda com padrão pleurítico, derrame pleural esquerdo, poliartrite e poliartralgia simétricas (padrão inflamatório) dos punhos, articulações interfalângicas proximais das mãos, joelhos e tibiotársicas, acompanhadas de rigidez matinal. Este quadro tinha dois meses de evolução e, após investigação, foi comprovado o diagnóstico de Lúpus Eritematoso Sistémico