Job separations, heterogeneity, and earnings inequality

Changes in the fraction of workers experiencing job separations can account for> most of the increase in earnings dispersion that occurred both between, as well as> within educational groups in the United States from the mid-1970s to the mid-> 1980s. This is not true of changes in average earnings losses following job separations.> A search model with exogenous human capital accumulation calibrated> to match some selected moments of the U.S. labor market is used to measure the> effects of changes in the fraction of workers experiencing job separations (extensive> margin) versus changes in average earnings losses following job separations> (intensive margin). While both margins do well in accounting for the increase in> the college premium, only the changes in the extensive margin do well in accounting> for the increases in the variance of both the permanent and transitory> components of earnings.Wages ; Income distribution

The Implications of Capital-Skill Complementarity in Economies with Large Informal Sectors

In most developing nations, formal workers tend to be more experienced and educated than informal workers, a fact often interpreted as evidence that low-skill workers face barriers to entry into the formal sector. Yet, there exists little direct evidence that labor markets are segmented in those nations. This paper describes a model where significant differences arise between workers across sectors even though labor markets are perfectly competitive. In equilibrium, the informal sector emphasizes low-skill work because informal managers have access to less outside financing, and choose to substitute low-skill labor for physical capital. We argue that subsidiary implications of the model for the organization of production are borne out by the existing evidence on informal economic activities in developing countries.

Finance matters

We present a model in which the importance of financial intermediation for development can be measured. We generate financial differences by varying the degree to which contracts can be enforced. Economies where enforcement is poor employ less capital and less efficient technologies. Yet, accounting for all the observed dispersion output requires a higher capital share or a lower elasticity of substitution between capital and labor than usually assumed. We find that the effects of changes in those technological parameters on output are markedly larger when financial frictions are present. Finance, that is, matters.Financial markets ; Productivity

A multi-sectoral approach to the U.S. Great Depression

We document sectoral differences in changes in output, hours worked, prices, and nominal wages in the United States during the Great Depression. We explore whether contractionary monetary shocks combined with different degrees of nominal wage frictions across sectors are consistent with both sectoral as well as aggregate facts. To do so, we construct a two-sector model where goods from each sector are used as intermediates to produce the sectoral goods that in turn produce final output. One sector is assumed to have flexible nominal wages, while nominal wages in the other sector are set using Taylor contracts. We calibrate the model to the U.S. economy in 1929, and then feed in monetary shocks estimated from the data. We find that while the model can qualitatively replicate the key sectoral facts, it can account for less than a third of the decline in aggregate output. This decline in output is roughly half as large as the one implied by a one-sector model. Alternatively, if wages are set using Calvo-type contracts, the decline in output is even smaller.Depressions ; Wages ; Prices

Turbulence, Heterogeneity, and Wage Earnings Inequality

There has been a well-documented increase in wage earnings inequality in the last two decades both in the United States as well as in other OECD economies. Moreover, this increase occurred not only across groups, but also within groups. There is also some evidence that this increase in inequality was accompanied by an increase in the pace of technological changes which require the learning of new skills, as well as by an increasese in occupational mobility.The question this paper asks is what are the consequences of (i) an increase in the depreciation rate of skills, or (ii) an increase in occupational mobility for wage earnings dispersion in an economy in which people learn new skills at different rates. To answer this question, a Ljungqvist and Sargent (1998) type of economy is modified to include two distinct populations. What distinguishes them is the rate at which they accumulate new skills while on the job. Skills are partly job specific, so if a particular job disappears, workers in that job experience a skill .When the rate at which skills depreciate, or occupational mobility, increase, there is an increase in the value of the ability to master new skills faster. In the context of a model calibrated to reproduce some statistics drawn from CPS and DWS data, such increases imply increases in inequality between fast learners and slow learners, but have little effect on withn-group inequality.

When Politicians Talk About Politics: Identifying Political Tweets of Brazilian Congressmen

Since June 2013, when Brazil faced the largest and most significant mass protests in a generation, a political crisis is in course. In midst of this crisis, Brazilian politicians use social media to communicate with the electorate in order to retain or to grow their political capital. The problem is that many controversial topics are in course and deputies may prefer to avoid such themes in their messages. To characterize this behavior, we propose a method to accurately identify political and non-political tweets independently of the deputy who posted it and of the time it was posted. Moreover, we collected tweets of all congressmen who were active on Twitter and worked in the Brazilian parliament from October 2013 to October 2017. To evaluate our method, we used word clouds and a topic model to identify the main political and non-political latent topics in parliamentarian tweets. Both results indicate that our proposal is able to accurately distinguish political from non-political tweets. Moreover, our analyses revealed a striking fact: more than half of the messages posted by Brazilian deputies are non-political.Comment: 4 pages, 7 figures, 2 table

A neural network based fall detector

In this project we present an intelligent fall detector system based on a 3-axis accelerometer and a neural network model that allows recognizing several possible motion situations and performing an emergency call only when a fall situation occurs, with low false negatives rate and low false positives rate. The system is based on a two module platform. The first one is a Mobile Station (MS) and should be carried always by the person. An accelerometer is implemented in this module and its information is transferred via a radio-frequency channel (RF) to the Base Station (BS). The BS is fixed and is connected to a GSM (Global System for Mobile communication) module. A neural network model was built into the BS and is able to identify falls from other possible motion situations, based on the received information. According to the neural network response the system sends a SMS (Short Message Service) to a destination number requesting for assistance

An antibiogram classificattion system based on an hybrid hough transform and gradient approach

The antibiogram performed by the disc diffusion method is a test frequently used in clinical microbiology. In this test, the result is given by the diameter of the inhibition zone formed around the antibiotic disco In general, this measurement is performed manually. The main objective of this work was to develop an automatic image analysis system to assess the susceptibility of microorganisms to different antibiotics. As a first step, several images of antibiograms were obtained. Subsequently the images were subjected to image processing techniques. After the elimination of noise, the Hough transform was used to detect the antibiotic discs. Next, from the center of each identified disc, the inhibition zone was detected recurring to a gradient method. According to the diameter of the inhibition zone a susceptibility classification was made. The results prove the validity of the developed tool to detect the antibiotics discs and to segment the inhibition zones used in microorganism's susceptibilfty evaluation