Cosmological parameter inference with Bayesian statistics

Bayesian statistics and Markov Chain Monte Carlo (MCMC) algorithms have found their place in the field of Cosmology. They have become important mathematical and numerical tools, especially in parameter estimation and model comparison. In this paper, we review some fundamental concepts to understand Bayesian statistics and then introduce MCMC algorithms and samplers that allow us to perform the parameter inference procedure. We also introduce a general description of the standard cosmological model, known as the $\Lambda$CDM model, along with several alternatives, and current datasets coming from astrophysical and cosmological observations. Finally, with the tools acquired, we use an MCMC algorithm implemented in python to test several cosmological models and find out the combination of parameters that best describes the Universe.Comment: 30 pages, 17 figures, 5 tables; accepted for publication in Universe; references adde

Argentina's labor markets in an era of adjustment

The current economic crisis in Argentina is only partly the result of inappropriate domestic policies to cope with the recent external shocks. Years of inappropriate policies have damaged Argentina's economy. Even if no external shocks had occurred, the country would still have to change the structure of production. Argentina has had trouble sustaining a program of structural adjustment. Its experiences provide policymakers with some lessons in designing a sustainable program to achieve price stability and change the incentive system : a) macroeconomic and trade policies must be consistent; b) labor relations and labor market institutions must be changed including the decentralization of wage bargaining and the elimination of traditional wage policies and general government intervention; c) rigidities and restrictions on labor mobility must be eliminated, leading to less pervasive government intervention in the form of restrictive regulations and spending patterns; and d) public spending must be profoundly changed to reduce social costs during the transition period.Economic Stabilization,Banks&Banking Reform,Municipal Financial Management,Environmental Economics&Policies,Economic Theory&Research

Wage responsiveness and labor market disequilibrium

The objectives of this paper are : (i) to empirically probe on the validity of the hypothesis that wages are relatively unresponsive to labor market disequlibrium; and (ii) to investigate whether the dramatically diverse rates of unemployment observed across certain Latin American countries obey fundamentally different wage dynamics or are the product of diversity in labor market distortions and other labor market policies. The indications found are that core unemployment may not affect market wages, whereas transient unemployment does. Policymaking should reflect the distinction.Environmental Economics&Policies,Youth and Governance,Economic Theory&Research,Labor Markets,Health Monitoring&Evaluation

Macroeconomic adjustment and the labor market in four Latin American countries

Implicit in standard macroeconomics of adjustment is the assumption of well-integrated labor markets that are responsive to relative prices. But segmentation of the labor market is usually said to be an important source of labor market rigidities. In particular, if segmentation involves different degrees of real wage rigidity among different groups in the labor force, nominal devaluation may be ineffective and inequitable in its impact. This paper uses a model of labor market segmentation in which regulations are necessary to distinguish between the formal and informal sectors. Using standard econometric techniques to estimate four simultaneous equations, the authors examine the effect of devaluation on relative wages in four countries. They found that formal wages are more responsive than informal wages to inflation and that devaluation of the exchange rate, by increasing the wage gap, is a source of sluggish labor mobility. In addition, they found that expanding wage differentials during adjustment imposes a greater burden on the poorest workers, making adjustment policies less politically sustainable. Finally, they found evidence to support the hypothesis that nominal devaluation would probably be ineffective with a segmented labor market.Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Labor Markets,Health Economics&Finance

Self-trapping of Fermi and Bose gases under spatially modulated repulsive nonlinearity and transverse confinement

We show that self-localized ground states can be created in the spin-balanced gas of fermions with repulsion between the spin components, whose strength grows from the center to periphery, in combination with the harmonic-oscillator (HO) trapping potential acting in one or two transverse directions. We also consider the ground state in the non-interacting Fermi gas under the action of the spatially growing tightness of the one- or two-dimensional (1D or 2D) HO confinement. These settings are considered in the framework of the Thomas-Fermi-von Weizsacker (TF-vW) density functional. It is found that the vW correction to the simple TF approximation (the gradient term) is nearly negligible in all situations. The properties of the ground state under the action of the 2D and 1D HO confinement with the tightness growing in the transverse directions is investigated too for the Bose-Einstein condensate (BEC) with the self-repulsive nonlinearity.Comment: 9 pages, 12 figures, to be published in Phys. Rev.

Low-frequency absorption cross section of the electromagnetic waves for the extreme Reissner-Nordstrom black holes in higher dimensions

We investigate the low-frequency absorption cross section of the electromagnetic waves for the extreme Reissner-Nordstrom black holes in higher dimensions. We first construct the exact solutions to the relevant wave equations in the zero-frequency limit. In most cases it is possible to use these solutions to find the transmission coefficients of partial waves in the low-frequency limit. We use these transmission coefficients to calculate the low-frequency absorption cross section in five and six spacetime dimensions. We find that this cross section is dominated by the modes with l=2 in the spherical-harmonic expansion rather than those with l=1, as might have been expected, because of the mixing between the electromagnetic and gravitational waves. We also find an upper limit for the low-frequency absorption cross section in dimensions higher than six.Comment: 7 pages, 1 figure, Phys. Rev. D (to appear

The Unruh effect and its applications

It has been thirty years since the discovery of the Unruh effect. It has played a crucial role in our understanding that the particle content of a field theory is observer dependent. This effect is important in its own right and as a way to understand the phenomenon of particle emission from black holes and cosmological horizons. Here, we review the Unruh effect with particular emphasis to its applications. We also comment on a number of recent developments and discuss some controversies. Effort is also made to clarify what seems to be common misconceptions.Comment: 53 pages, 11 figures, submitted to Reviews of Modern Physic