Mudança estrutural e mercado de trabalho no Brasil

Structural changes and labor market in Brazil. In the present article, we attempt to identify the sources of the changes in the labor schooling level in the three main sectors of the Brazilian economy: manufacturing, services and agriculture. It was verified that, despite the changes in the product and employment among sectors, mainly in the 1990s, the relative demands for qualified workers has not experimented significant changes. Moreover, in the periods in which schooling has increased more, the workers' wage has decreased more. This fact suggests that the increase in labor qualification was mainly due to the increase of this factor supply. The structural changes had contributed, in general, in a marginal and negative way to labor force level of qualification demand in all the three sectors.

Dynamical changes from harmonic vibrations of a limited power supply driving a Duffing oscillator

The harmonic oscillations of a Duffing oscillator driven by a limited power supply are investigated as a function of the alternative strength of the rotor. The semi-trivial and non-trivial solutions are derived. We examine the stability of these solutions and then explore the complex behaviors associated with the bifurcations sequences. Interestingly, a 3D diagram provides a global view of the effects of alternate strength on the appearance of chaos and hyperchaos on the system.