On the variational homotopy perturbation method for nonlinear oscillators

In this paper we discuss a recent application of a variational homotopy perturbation method to rather simple nonlinear oscillators . We show that the main equations are inconsistent and for that reason the results may be of scarce utility

Economic transition and the distributions of income and wealth

Using a model of wealth distribution dynamics and occupational choice, the author investigates the distributional consequences of policies and developments associated with the transition from central planning to a market system. The model suggests that even an efficient privatization designed to be egalitarian may lead to increases in inequality (and possibly poverty), both during the transition and in the new steady state. Creating new markets in services that are also supplied by the public sector may also contribute to an increase in inequality. So can labor market reforms that lead to a decompression of the earnings structure and to greater flexibility in employment. The results underline the importance of retaining government provision of basic public goods and services, removing barriers that prevent the participation of the poor in the new private sector, and ensuring that suitable safety nets are in place.Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Fiscal&Monetary Policy,Labor Policies,Banks&Banking Reform,Health Economics&Finance,Economic Theory&Research,Inequality,Environmental Economics&Policies

Distributions in motion: economic growth, inequality, and poverty dynamics

The joint determination of aggregate economic growth and distributional change has been studied empirically from at least three different perspectives. A macroeconomic approach that relies on cross-country data on poverty, inequality, and growth rates has generated some interesting stylized facts about the correlations between these variables, but has not shed much light on the underlying determinants."Meso-"and microeconomic approaches have fared somewhat better. The microeconomic approach, in particular, builds on the observation that growth, changes in poverty, and changes in inequality are simply different aggregations of information on the incidence of economic growth along the income distribution. This paper reviews the evolution of attempts to understand the nature of growth incidence curves, from the statistical decompositions associated with generalizations of the Oaxaca-Blinder method, to more recent efforts to generate"economically consistent"counterfactuals, drawing on structural, reduced-form, and computable general equilibrium models.Rural Poverty Reduction,Achieving Shared Growth,Inequality,Services&Transfers to Poor,Economic Theory&Research

Electrically charged finite energy solutions of an SO(5)SO(5) and an SU(3)SU(3) Higgs-Chern-Simons--Yang-Mills-Higgs systems in 3+13+1 dimensions

We study spherically symmetric finite energy solutions of two Higgs-Chern-Simons--Yang-Mills-Higgs (HCS-YMH) models in $3+1$ dimensions, one with gauge group $SO(5)$ and the other with $SU(3)$. The Chern-Simons (CS) densities are defined in terms of both the Yang-Mills (YM) and Higgs fields and the choice of the two gauge groups is made so they do not vanish. The solutions of the $SO(5)$ model carry only electric charge and zero magnetic charge, while the solutions of the $SU(3)$ model are dyons carrying both electric and magnetic charges like the Julia-Zee (JZ) dyon. Unlike the latter however, the electric charge in both models receives an important contribution from the CS dynamics. We pay special attention to the relation between the energies and charges of these solutions. In contrast with the electrically charged JZ dyon of the Yang-Mills-Higgs (YMH) system, whose mass is larger than that of the electrically neutral (magnetic monopole) solutions, the masses of the electrically charged solutions of our HCS-YMH models can be smaller than their electrically neutral counterparts in some parts of the parameter space. To establish this is the main task of this work, which is performed by constructing the HCS-YMH solutions numerically. In the case of the $SU(3)$ HCS-YMH, we have considered the question of angular momentum, and it turns out that it vanishes.Comment: 20 pages, 10 figure

Does Duality Theory Hold in Practice? A Monte Carlo Analysis for U.S. Agriculture

The Neoclassical theory of production establishes a dual relationship between the profit value function of a competitive firm and its underlying production technology. This relationship, usually referred to as the duality theory, has been widely used in empirical work to estimate production parameters without the requirement of explicitly specifying the technology. We analyze the ability of this approach to recover the underlying production parameters and its effects on estimated elasticities and scale economies measurements, when data available for estimation features typical realistic problems. We design alternative scenarios and compute the data generating process by Monte Carlo simulations, so as to know the true technology parameters as well as to calibrate the dataset to yield realistic magnitudes of noise. This noise introduced in the estimation by construction prevents duality theory from holding exactly. Hence, the true production parameters may not be recovered with enough precision, and the estimated elasticities or scale economies measurements may be more inaccurate than expected. We compare the estimated production parameters with the true (and known) parameters by means of the identities between the Hessians of the production and profit functions.duality theory, firm’s heterogeneity, measurement error, data aggregation, omitted variables, endogeneity, uncertainty, Monte Carlo simulations., Crop Production/Industries, Production Economics, Risk and Uncertainty, Q12, D22, D81,

Inequality of Outcomes and Inequality of Opportunities in Brazil

This paper departs from John Roemer's theory of equality of opportunities. We seek to determine what part of observed outcome inequality may be attributed to differences in observed 'circumstances', including family background, and what part is due to 'personal efforts'. We use a micro-econometric technique to simulate what the distribution of outcomes would look like if 'circumstances' were the same for everybody. This technique is applied to Brazilian data from the 1996 household survey, both for earnings and for household incomes. It is shown that observed circumstances are a major source of outcome inequality in Brazil, probably more so than in other countries for which information is available. Nevertheless, the level of inequality after observed circumstances are equalized remains very high in Brazil.http://deepblue.lib.umich.edu/bitstream/2027.42/40016/3/wp630.pd

Non Abelian Chern-Simons-Higgs solutions in (2+1) dimensions

Non Abelian vortices of a SU(2) Chern-Simons--Higgs theory in 2+1 dimensions are constructed numerically. They represent natural counterparts of the U(1) solutions considered by Hong, Kim and Pac, and, by Jackiw and Weinberg. The Abelian embeddings are identified, for all values of the Higgs selfinteraction strength $\nu$, resulting in both attractive and repulsive phases. A detailed analysis of the properties of the solutions reveals the existence ofa number of unexpected features. For a certain range of the parameter $\nu$, it is shown that the non Abelian vortices have lower energy than their topologically stable Abelian counterparts, resulting in an effective energy lower bound on the SU(2) configurations. The angular momentum of these vortices is analysed and it is found that unlike the Abelian ones, whose angular momentum and energy are unrelated, there is a nontrivial mass--spin relation of the non Abelian vortices.Comment: 16 pages, 11 figure