Optimal Technology and Development

Skill intensive technologies seem to be adopted by rich countries rather than poor ones. Related to that observation, the ratio of wages of skilled to unskilled workers - the skill premium - shows two important features over time and across countries. In the US the skill premium decreased during the first half of the 20th century and it increased after 1950, evolving according to a U shaped pattern. On the other hand, the same measure across countries around 1990 is hump shaped when countries are ordered by GDP per worker. By modeling the decisions for factor accumulation and technology adoption, this paper gives a systematic explanation as to why we see ever more skill intensive technologies being adopted both over time in the US and across countries. The model developed here endogenously generates predictions for the skill premium that are consistent with both the US and international observations under the same set of parameter values.Technology adoption; growth

A gibbad-satterthwaite theorem for public good economies

We study the properties of mechanisms for deciding upon the provision of public goods when the feasible set is exogenously given (by financial and/or technological constraints), and individuals' preferences are represented by continuous, increasing and concave utility functions, and we establish a result analog to the Gibbard-Satterthwaite Theorem: strategy-proof mechanisms are dictatorial. Further, efficient and strategy-proof mechanisms are strongly dictatorial (i.e., maximize the dictator's welfare on the entire feasible set.

Optimal Technology, Development and the role of Government

This paper highlights the effect of the presence of the goverment and its redistribution policy in the technology adoption decision. As a result it helps explain the differences in skill premium patterns across the North Atlantic between developed economies such as the US and Continental Europe.Taxes, skill biased technological change; skill premium; endogenous technology; inequality

Former Communist Countries and their transition to Capitalism

This paper uses the technology adoption general equilibrium model developed by Moscoso Boedo (2006) to analyze the transition for the countries of the former USSR and Eastern Europe. There the real output displayed a U-shapped pattern together with increases in inequality, which are features matched by the modelTransition economies, skill biased technological change; skill premium; endogenous technology; inequality

Illumination strategies for intensity-only imaging

We propose a new strategy for narrow band, active array imaging of localized scat- terers when only the intensities are recorded and measured at the array. We consider a homogeneous medium so that wave propagation is fully coherent. We show that imaging with intensity-only measurements can be carried out using the time reversal operator of the imaging system, which can be obtained from intensity measurements using an appropriate illumination strategy and the polarization identity. Once the time reversal operator has been obtained, we show that the images can be formed using its singular value decomposition (SVD). We use two SVD-based methods to image the scatterers. The proposed approach is simple and efficient. It does not need prior information about the sought image, and guarantees exact recovery in the noise-free case. Furthermore, it is robust with respect to additive noise. Detailed numerical simulations illustrate the performance of the proposed imaging strategy when only the intensities are captured

Array imaging of localized objects in homogeneous and heterogeneous media

We present a comprehensive study of the resolution and stability properties of sparse promoting optimization theories applied to narrow band array imaging of localized scatterers. We consider homogeneous and heterogeneous media, and multiple and single scattering situations. When the media is homogeneous with strong multiple scattering between scatterers, we give a non-iterative formulation to find the locations and reflectivities of the scatterers from a nonlinear inverse problem in two steps, using either single or multiple illuminations. We further introduce an approach that uses the top singular vectors of the response matrix as optimal illuminations, which improves the robustness of sparse promoting optimization with respect to additive noise. When multiple scattering is negligible, the optimization problem becomes linear and can be reduced to a hybrid-$\ell_1$ method when optimal illuminations are used. When the media is random, and the interaction with the unknown inhomogeneities can be primarily modeled by wavefront distortions, we address the statistical stability of these methods. We analyze the fluctuations of the images obtained with the hybrid-$\ell_1$ method, and we show that it is stable with respect to different realizations of the random medium provided the imaging array is large enough. We compare the performance of the hybrid-$\ell_1$ method in random media to the widely used Kirchhoff migration and the multiple signal classification methods

Sectoral Reallocation, Growth and Labor Income Inequality

This paper focuses on the transitory relationship between output level and Income inequality. As a result of either permanent or transitory sectoral technological shocks the economy will adjust to a new steady state equilibrium, but during the transition the dynamics of wages and workers will generate departures from the steady state level of income inequality.inequality, productivity

Optimal Technology and Development

Skill intensive technologies seem to be adopted by rich countries rather than poor ones. Related to that observation, the ratio of wages of skilled to unskilled workers - the skill premium - shows two important features over time and across countries. In the US the skill premium decreased during the first half of the 20th century and it increased after 1950, evolving according to a U shaped pattern. On the other hand, the same measure across countries around 1990 is hump shaped when countries are ordered by GDP per worker. By modeling the decisions for factor accumulation and technology adoption, this paper gives a systematic explanation as to why we see ever more skill intensive technologies being adopted both over time in the US and across countries. The model developed here endogenously generates predictions for the skill premium that are consistent with both the US and international observations under the same set of parameter valuesskill biased technological change; skill premium,endogenous technology; inequality