Erik Alencar de Figueiredo

Schistosoma mansoni: mechanism of cercarial tail loss and its significance to host penetration.

Abstract The mechanism of tail loss from cercariae of Schistosoma mansoni was investigated under experimental conditions. Tail loss from 90% or more of cercariae occurred in less than 10 min when packed organisms were incubated at 30 C in a minimal volume of water. Proteolytic secretions from the acetabular glands did not play a significant part in this process since the addition of known protease inhibitors nor the addition of secretions collected from other cercariae influenced the rate of the process. Tail loss was inhibited when the packed cercariae were incubated in saline at concentrations of 0.05 M or above though glandular secretion occurred at an equal rate in both water and saline. Tail loss was also inhibited by the chelating agents ethylenediaminotetraacetic acid (EDTA) and ethyleneglycoltetraacetic acid (EGTA). A marked feature of cercariae packed in water was their clumping and adhesion to the walls of the containing vessel by secretions from the postacetabular glands. Such clumping did not occur in saline or chelant solutions. It is suggested that the most probable mechanism for tail loss is a simple mechanical trauma effected by the movement of the tail acting against the resistance of the secretion-fixed body. During incubation under conditions which remove the “coat” from the body of the cercaria, the “coat” of the tail remains intact.

Inflação inercial como um processo de longa memória: análise a partir de um modelo Arfima-Figarch

O objetivo principal deste estudo e investigar a dependencia de longo prazo da inflacao brasileira, descrevendo-a como um processo fracionariamente integrado tanto na media quanto na variância. A metodologia empregada baseia-se na estimacao de um modelo ARFIMA-FIGARCH, capaz de detectar a presenca de memoria longa em altas defasagens de um processo autorregressivo. Os principais resultados alcancados indicam que, para o periodo pos-Plano Real, a inflacao brasileira exibe um comportamento estacionario em seus dois primeiros momentos com lento decaimento hiperbolico. Ha indicios de longa memoria na media e na variância do processo. Alem disso, constatou-se, para esse periodo, uma reciproca influencia entre a volatilidade e a taxa media de inflacao.

Mudança na distribuição de renda brasileira: significância estatística e bem-estar econômico

This study aims at verifying a statistically significant change in Brazilian income distribution during the period between 1987 and 2005. To do so we adopt several statistical tools, as the calculation of standard deviations of inequality measures, Kolmogorov-Smirnov test, nonparametric density estimation via kernel smoothing and bootstrap, and stochastic dominance of first and second orders. The results point to a significative change in the income distributive pattern. Finally, we conclude that changes in income distribution are related to higher levels of economic welfare.

Inflação inercial sob mudanças de regime: análise a partir de um modelo MS-ARFIMA, 1944-2009

The main goal of this paper is search for the long run dependence in the Brazilian inflation rate allowing regime switching by the MS-ARFIMA model. The principal contribution of this paper is the simultaneous and consistent estimation of longmemory coefficient d and the several regimes that encompass them. The results enable us to conclude that there were two regimes in the Brazilian economy with high persistence: hyperinflation regime and low inflation regime. The long run memory of inflation rate is dependent upon regime switching. The low inflation regime is the more persistent one.

Poverty Elasticity: A Note on a New Empirical Approach

This note proposes a non‐parametric estimation method controlled for endogeneity to calculate poverty elasticities for a panel of countries. Results show that usual linear estimates without control for endogeneity overestimate the growth elasticity of poverty.

Persistência das Desigualdades Regionais no Brasil- Polarização e Divergência

This paper aims to evaluate the recent dynamics of the regional development in Brazil assuming that the recent fall in income inequality does not indicate income convergence. The income polarization index shows that when Brazil is divided in the subsets North/Northeast and the rest of the country, there is greater identification of states and municipalities within each group (poor with poor and rich with rich), and an increase of the distance between them. In this sense, the reduction of total inequality reflects a process of income divergence.

Migration and Regional Trade Agreements: A (New) Gravity Estimation

This paper investigates the role of regional trade agreements (RTAs) on bilateral international migration. Building on a gravity model for migration, our econometric strategy controls for the multilateral resistance to migration and solves the zero migration flows problem by using a censored quantile regression approach. Further, the endogeneity problem of RTAs in migration settlement is addressed by using instrumental variable censored quantile regression. Our results suggest that the presence of a RTA stimulates the migration stocks among member countries. The pro‐migration effect of RTAs is magnified if the agreement includes also provisions easing bureaucratic procedures for visa and asylum among member countries. Finally, we find an asymmetric effect of RTAs across the quantiles of the distribution of migration settlements.

Uma Análise para o Efeito-Fronteira no Brasil

Este artigo analisa o efeito fronteira para o comercio internacional brasileiro. Considera-se a equacao gravitacional estrutural de Anderson e Wincoop (2003) e as recomendacoes de Baldwin e Taglioni (2006, 2011). A estrategia econometrica e robusta frente ao grande numero de relacoes comerciais iguais a zero e as possiveis formas funcionais desconhecidas e heterocedasticas do termo de erro aleatorio. Os resultados sugerem que o elevado efeito fronteira, largamente corroborado pela literatura nacional, e fruto da ma especificacao da equacao gravitacional, em especial da nao inclusao dos termos de resistencia multilateral sugeridos por Anderson e Wincoop (2003).

Mobilidade intrageracional de renda no Brasil

The purpose of this study is to measure intragenerational income mobility in Brazil and its several population subgroups within the period 1995-2005. To this end, the mobility axiomatic approach and dynamic instruments proposed by Aebi et al. (1999) are considered. Calculations of mobility indexes and the Markov transaction matrix indicate that Brazil presents low intragenerational income mobility, suggesting that its social structure is relatively rigid. Also, important heterogeneities within each subgroup were observed, thus corroborating the intergenerational results indicated by Ferreira and Veloso (2006).

Algumas simulações de efeitos de mobilidade de renda sobre o nível de bem-estar

This study intends to measure the relationship between Brazilian economic welfare and income mobility. To achieve that it was used a model of intertemporal consumption proposed by Gottschalk e Spolaore (2002). This theoretical support allows to evaluate isolated the two sources of mobility: the reversibility and the source independence. The simulations suggest that flexibilizantion of Brazilian social structure, represented by an increase of income mobility, results a positive impact on the economic welfare.