ABSTRACT Agroecological management is considered a model of sustainable agriculture that offers social, environmental and economic benefits. The hypotheses of this study were that agroecological production systems can promote changes in the physical fractions of soil organic matter (SOM) associated with aggregates of different origins, and that the greater diversity of plant species in the production system may favour an increase in the carbon concentration of these aggregates. The aim of this study was to a) determine the mass of the free light fraction (FLF), intra-aggregate light fraction (ILF) and light organic matter fraction (LOM) of biogenic and physiogenic soil aggregates; and b) quantify the organic carbon content of the three light SOM fractions and the residual particulate SOM fraction. Five production systems were evaluated: AgF - Agroforestry system; CSun - Coffee grown in full sun; CSha - Coffee grown in shade; FLE - Flemingia grown in alleys; and NT - No-tillage. The aggregates were separated, identified and classified according to their origin or formation pathway into biogenic (formed by biological processes) or physiogenic aggregates (resulting from chemical and physical actions). From these, the mass and carbon content of the FLF, ILF, LOM and residual particulate fractions were quantified. The greater diversity of plant species found in the AgF system has not yet favoured an increase in the carbon content of the aggregates. The longer set-up time and the management practices of the CSun system has led to an increase in the carbon content of the organic fractions of the aggregates (3.44-1.63 g kg-1 for C-LOM; 1.93-1.13 g kg-1 for C-FLF). The lowest overall mean values for LOM and ILF were found mainly in the aggregates of the NT system (1.22-1.67 and 1.55-2.20 g kg-1, respectively), being associated with the shorter time and greater mobilisation of the arable layer. Biogenic aggregation afforded the highest overall mean values for LOM, and increased the mass of the light fractions (15.5%-27.8% for FLF; 23.4%-8.0% for ILF) and the carbon in the C-LOM, C-FLF and residual particulate fractions (42.3%, 12.9%, and 35.0%, respectively) in the surface layer, suggesting an improvement in soil quality.

ABSTRACT Sandy texture soils have a great expression in agricultural areas worldwide. In the Baixada Fluminense, soils with a sandy texture on the surface horizons are striking, and a good part of these areas is destined for producing vegetables using conventional cultivation methods. The sandy texture is one of the great challenges for agriculture due to the low water retention capacity provided to the soil, the rapid decomposition of organic matter, and the intense loss of nutrients by leaching. In these areas, the action of erosive processes is sometimes observed, whether water or wind erosion. The practices carried out in conventional agriculture can accentuate these processes. This study aimed to evaluate the influence of different soil management systems, with different vegetation covers, on the pathways of aggregate formation, the nutrient contents contained therein, and the organic matter fractions, with the objective of using these properties as indicators of soil quality. The study was carried out in an organic production unit, with no-till system (NT) and conventional system (CT), three vegetal covers were evaluated, namely; seed cocktail 1 (C1) (Crotalaria (Crotalaria juncea) (20 kg ha-1), Jack Bean (Canavalia ensiformis) (150 kg ha-1) and millet (Pennisetum glaucum) (60 kg ha-1)), and seed cocktail 2 (C2) (with 50 % of the amount of seeds used in C1), and spontaneous plants (S. P). Undisturbed samples were collected at the layers of 0.00-0.05 and 0.05-0.10 m, and, from these samples, aggregates with a diameter between 9.7 and 8.0 mm were classified according to the formation route (Biogenic or Physicogenic). From these, the chemical properties were quantified (pH, Ca2+, Mg2+, Al3+, P, Na+, K+), and also the carbon fractions (total organic carbon – TOC, mineral-associated organic carbon – MAOC), particulate organic carbon – POC, and free light fraction carbon – LFC). Based on the results, it was verified that the percentage of biogenic aggregates was higher than the physicogenic one in the layer of 0.00-0.05 m, not being verified influences of the vegetal coverage or the management system. Chemical properties did not differ significantly between training pathways. The CT, for the most part, was the system in which the highest values of chemical properties were observed, and in general, the C2 and S.P coatings were the ones that provided the greatest improvements for chemical properties and carbon content.

ABSTRACT State parks are integral protection units created to protect ecosystems. However, anthropic activities may have been previously performed before their creation, forming transitional areas. Studies that evaluate the modifications of edaphic properties in these environments are scarce. The aim of this study was to evaluate the changes in soil properties and litter stock in areas of eucalyptus-forest ecotones. Litter stock (Stocklitter) and total soil organic carbon content and stock (TOCsoil), weighted mean diameter (MWD), origin of aggregates (biogenic or physicogenic) and respective content of total organic carbon (TOCBio and TOCPhy), total organic carbon (TOCAG), soil organic matter chemical fractions [fulvic acid (FAC), humic (HAC), and humin (HUMC)], and particulate, mineral-associated, free light and intra-aggregate light (POC, MAOC, FLFC, and ILFC) soil organic matter, fertility, and glomalin-related soil protein (GRSP) fractions were evaluated in aggregates (layer 0.00-0.10 m) in areas of eucalyptus-forest ecotone (Eco), preserved forest fragment (For), and eucalyptus plantation (Euc), in Nova Baden State Park, Lambari–MG. In the Euc and Eco areas, the highest Stocklitter content was found. Higher values of TOCsoil, TOCAG, GRSP, and MWD were observed in the Euc area. In the biogenic aggregates, the highest content of TOCBio, HAC, HUMC, POC, MAOC, FLFC, and ILFC was determined in detriment of the physicogenic ones. The dynamics of edaphic properties in the Eco area showed greater similarity with the For area than in the Euc area. In general, all vegetation covers contribute to the maintenance of soil quality.

Abstract Fish age can be estimated with the use of age rings in calcified structures, such as otoliths. However, it is important to select an appropriate axis for counting the number of increments and to confirm that the age rings are visible in the otolith and interpreted correctly. In this study, the distance between consecutive age rings in the lapillus otoliths of Cathorops spixii and Genidens genidens catfish from the Cananéia-Iguape Estuarine– Lagoon Complex was measured along otoliths at predetermined 90° and 150° axes. In general, the number of increments observed per otolith ranged from 1 to 14 for both species. The positive linear relationship between the total length of the fish and the radius of the age rings suggests that otolith size is a reliable somatic proxy of C. spixii (=0.872) and G. genidens (=0.896). The axes chosen to measure the distances of each increment were proven accurate, especially the straight axis. Our study indicates that the 90º and 150º angles can be used for increment counting, but caution is required for otoliths with the same growth morphology: potentially confusing increments are more prevalent along the 150º axis, and this may hinder increment analysis of G. genidens and C. spixii. Therefore, the 90º axis provides better visualization of the closest opaque and translucent zones and should be prioritized for increment counting in the C. spixii and G. genidens ariids.

Abstract Some fish species can be used as target species and bioindicators of environmental disturbances. In this context, biological indicators such as the length, weight, and height of lapillus otoliths of the ariid species Cathorops spixii and Genidens genidens were considered bioindicators of contamination of the Cananéia-Iguape estuarinelagoon complex (CIELC) in this study. The CIELC is an estuary with spatial and temporal differences regarding its hydrobiochemical properties and this characteristic has been related to changes in biological predictors such as the otolith morphometrics of estuarine fish. Therefore, this study aimed to verify the responses of otolith dimensions to sexual and temporal changes, throughout the CIELC. In total, 163 wild catfish C. spixii and 55 G. genidens were collected during the winter period of 2009, 2017, and 2018 in the CIELC. In general, the weight and length of lapillus otoliths of C. spixii and G. genidens were good metrics adjusted to fish growth. Females of C. spixii were significantly larger than males and subadults and there were no significant differences regarding the sexual approach of G. genidens. The temporal approach showed significant differences between the years for both catfish. C. spixii sampled in 2009 and 2018 showed greater total length (TL) and total weight (TW) when compared with fish from 2014 and 2017 (p < 0.05). G. genidens collected in 2018 had greater TL and TW than the specimens sampled in the other years (p < 0.05). Otolith dimensions seem to have followed this same pattern, since females of C. spixii had higher values for otolith weight, height, and length than males and subadults (p < 0.05). The data obtained in this study can be a potential tool for application combined with other ecological analyses and conservation studies in the CIELC.

Nuestro objetivo es describir las diferencias en los diseños muestrales de las dos ediciones de la Encuesta Nacional de Salud (PNS 2013 y 2019) y evaluar cómo sus cambios afectaron el coeficiente de variación (CV) y el efecto de diseño (Deff) de algunos de los indicadores evaluados. Se analizaron variables de diferentes partes del cuestionario para evaluar proporciones con diferentes magnitudes. La prevalencia de obesidad se incluyó en el análisis, ya que la medición de la antropometría en la encuesta de 2019 se realizó en una submuestra. Los valores del estimador puntual, CV y Deff se calcularon para cada indicador considerando la estratificación de las unidades de muestreo primarias, la ponderación de las unidades de muestreo y el efecto de agrupamiento. Para la mayoría de los indicadores, CV y Deff fueron más bajos en las estimaciones de 2019. En cuanto a los indicadores para todos los miembros de la familia, los Deff fueron altos y alcanzaron valores superiores a 18 por tener un plan de salud. En cuanto a los indicadores del cuestionario individual, Deff osciló entre 2,7 y 4,2 en 2013, y entre 2,7 y 10,2 en 2019 para la prevalencia de obesidad. La prevalencia de hipertensión arterial y diabetes por Unidad Federativa tuvo mayor CV y menor Deff. Un mayor tamaño de la muestra para cumplir con los diversos objetivos de salud y un alto valor de Deff son desafíos importantes para el desarrollo de una encuesta nacional domiciliar probabilística. Se deben considerar nuevas estrategias de muestreo probabilístico para reducir los costos y efectos de agrupamiento.

Nosso objetivo é descrever as diferenças nos desenhos amostrais das duas edições da Pesquisa Nacional de Saúde (PNS 2013 e 2019) e avaliar como suas mudanças afetaram o coeficiente de variação (CV) e o efeito do desenho (Deff) de alguns dos indicadores avaliados. Variáveis de diferentes partes do questionário foram analisadas para avaliar proporções com diferentes magnitudes. A prevalência de obesidade foi incluída na análise uma vez que a medição de antropometria na pesquisa de 2019 foi realizada em uma subamostra. Os valores do estimador pontual, CV e Deff foram calculados para cada indicador considerando a estratificação das unidades amostrais primárias, a ponderação das unidades amostrais, e o efeito do agrupamento. Para a maioria dos indicadores, CV e Deff foram menores nas estimativas de 2019. Em relação aos indicadores para todos os membros familiares, Deffs foram elevados e atingiram valores superiores a 18 para a posse de um plano de saúde. Quanto aos indicadores no questionário individual, Deff variou de 2,7 a 4,2 em 2013 e de 2,7 a 10,2 em 2019 para a prevalência de obesidade. A prevalência de hipertensão arterial e diabetes por Unidade Federativa apresentou CV maior e Deff menor. A expansão do tamanho da amostra para atender aos diversos objetivos de saúde e Deff altos são desafios expressivos para o desenvolvimento de uma pesquisa nacional domiciliar probabilística. Novas estratégias de amostragem probabilística devem ser consideradas para reduzir custos e efeitos do agrupamento.

Our objective is to describe the differences in the sampling plans of the two editions of the Brazilian National Health Survey (PNS 2013 and 2019) and to evaluate how the changes affected the coefficient of variation (CV) and the design effect (Deff) of some estimated indicators. Variables from different parts of the questionnaire were analyzed to cover proportions with different magnitudes. The prevalence of obesity was included in the analysis since anthropometry measurement in the 2019 survey was performed in a subsample. The value of the point estimate, CV, and the Deff were calculated for each indicator, considering the stratification of the primary sampling units, the weighting of the sampling units, and the clustering effect. The CV and the Deff were lower in the 2019 estimates for most indicators. Concerning the questionnaire indicators of all household members, the Deffs were high and reached values greater than 18 for having a health insurance plan. Regarding the indicators of the individual questionnaire, for the prevalence of obesity, the Deff ranged from 2.7 to 4.2, in 2013, and from 2.7 to 10.2, in 2019. The prevalence of hypertension and diabetes per Federative Unit had a higher CV and lower Deff. Expanding the sample size to meet the diverse health objectives and the high Deff are significant challenges for developing probabilistic household-based national survey. New probabilistic sampling strategies should be considered to reduce costs and clustering effects.

Nosso objetivo é descrever as diferenças nos desenhos amostrais das duas edições da Pesquisa Nacional de Saúde (PNS 2013 e 2019) e avaliar como suas mudanças afetaram o coeficiente de variação (CV) e o efeito do desenho (Deff) de alguns dos indicadores avaliados. Variáveis de diferentes partes do questionário foram analisadas para avaliar proporções com diferentes magnitudes. A prevalência de obesidade foi incluída na análise uma vez que a medição de antropometria na pesquisa de 2019 foi realizada em uma subamostra. Os valores do estimador pontual, CV e Deff foram calculados para cada indicador considerando a estratificação das unidades amostrais primárias, a ponderação das unidades amostrais, e o efeito do agrupamento. Para a maioria dos indicadores, CV e Deff foram menores nas estimativas de 2019. Em relação aos indicadores para todos os membros familiares, Deffs foram elevados e atingiram valores superiores a 18 para a posse de um plano de saúde. Quanto aos indicadores no questionário individual, Deff variou de 2,7 a 4,2 em 2013 e de 2,7 a 10,2 em 2019 para a prevalência de obesidade. A prevalência de hipertensão arterial e diabetes por Unidade Federativa apresentou CV maior e Deff menor. A expansão do tamanho da amostra para atender aos diversos objetivos de saúde e Deff altos são desafios expressivos para o desenvolvimento de uma pesquisa nacional domiciliar probabilística. Novas estratégias de amostragem probabilística devem ser consideradas para reduzir custos e efeitos do agrupamento.

Our objective is to describe the differences in the sampling plans of the two editions of the Brazilian National Health Survey (PNS 2013 and 2019) and to evaluate how the changes affected the coefficient of variation (CV) and the design effect (Deff) of some estimated indicators. Variables from different parts of the questionnaire were analyzed to cover proportions with different magnitudes. The prevalence of obesity was included in the analysis since anthropometry measurement in the 2019 survey was performed in a subsample. The value of the point estimate, CV, and the Deff were calculated for each indicator, considering the stratification of the primary sampling units, the weighting of the sampling units, and the clustering effect. The CV and the Deff were lower in the 2019 estimates for most indicators. Concerning the questionnaire indicators of all household members, the Deffs were high and reached values greater than 18 for having a health insurance plan. Regarding the indicators of the individual questionnaire, for the prevalence of obesity, the Deff ranged from 2.7 to 4.2, in 2013, and from 2.7 to 10.2, in 2019. The prevalence of hypertension and diabetes per Federative Unit had a higher CV and lower Deff. Expanding the sample size to meet the diverse health objectives and the high Deff are significant challenges for developing probabilistic household-based national survey. New probabilistic sampling strategies should be considered to reduce costs and clustering effects.

Nuestro objetivo es describir las diferencias en los diseños muestrales de las dos ediciones de la Encuesta Nacional de Salud (PNS 2013 y 2019) y evaluar cómo sus cambios afectaron el coeficiente de variación (CV) y el efecto de diseño (Deff) de algunos de los indicadores evaluados. Se analizaron variables de diferentes partes del cuestionario para evaluar proporciones con diferentes magnitudes. La prevalencia de obesidad se incluyó en el análisis, ya que la medición de la antropometría en la encuesta de 2019 se realizó en una submuestra. Los valores del estimador puntual, CV y Deff se calcularon para cada indicador considerando la estratificación de las unidades de muestreo primarias, la ponderación de las unidades de muestreo y el efecto de agrupamiento. Para la mayoría de los indicadores, CV y Deff fueron más bajos en las estimaciones de 2019. En cuanto a los indicadores para todos los miembros de la familia, los Deff fueron altos y alcanzaron valores superiores a 18 por tener un plan de salud. En cuanto a los indicadores del cuestionario individual, Deff osciló entre 2,7 y 4,2 en 2013, y entre 2,7 y 10,2 en 2019 para la prevalencia de obesidad. La prevalencia de hipertensión arterial y diabetes por Unidad Federativa tuvo mayor CV y menor Deff. Un mayor tamaño de la muestra para cumplir con los diversos objetivos de salud y un alto valor de Deff son desafíos importantes para el desarrollo de una encuesta nacional domiciliar probabilística. Se deben considerar nuevas estrategias de muestreo probabilístico para reducir los costos y efectos de agrupamiento.

ABSTRACT An important strategy for the sustainable management of Cerrado soils is no-till (NT) systems, which may improve soil properties, particularly aggregation. Soil aggregates can be categorized according to their formation pathways into physicogenic (Phy) and biogenic (Bio). This study aimed (i) to quantify the relative proportion of physicogenic and biogenic aggregates and (ii) evaluate the levels of total organic carbon and their respective humic and physical fractions in the aggregates’ formation pathways. The following managed and unmanaged sites were evaluated: a 6-year no-till site (6NT), an 18-year no-till site (18NT), a conventional tillage site (CT), and a reference Cerrado site (RS). Retained aggregates were analyzed morphologically, separated into Phy and Bio, and quantified. Subsequently, aggregates were subjected to total organic carbon (TOC) determination, fulvic acid carbon, humic acid carbon, humin carbon, particulate organic carbon (POC), mineral-associated organic carbon, and free light fraction carbon (FLFC). The proportion of Bio aggregates increased with decreasing management intensity. When TOC and humic acid carbon levels were compared between sites, it was found that Bio aggregates from 18NT and 6NT contained higher carbon content than Bio aggregates from CT. Particulate organic carbon and FLFC differed between aggregate types, with higher POC values observed in Bio aggregates from CT and 18NT and higher FLFC values in Bio aggregates from CT, 6NT, and 18NT. The practices adopted in the conservation management system favored biogenic aggregation in the Cerrado region, which can be proven through the study of the fractions of soil organic matter contained in these aggregates. The biogenic aggregation changed the SOM dynamics. Principal component analysis showed a clear distinction between conventional and conservationist management systems.

RESUMO Racional: Muitas são as injúrias que acometem o fígado e levam a estímulo lesivo. Alguns procedimentos terapêuticos para tratamento dessas lesões dependem da regeneração hepática para aumentar a sua capacidade funcional. Objetivo: Avaliar o efeito do ácido tranexâmico na regeneração hepática após hepatectomia parcial em ratos. Método: Foram utilizados 40 ratos (Rattus norvegicus albinus, Rodentia mammalia) convencionais da linhagem Wistar-UP. Foram divididos aleatoriamente em dois grupos de 20: grupo controle (CT) e grupo ácido tranexâmico (ATX). Cada um deles foi divido em dois subgrupos para avaliar a regeneração hepática no tempo de 32 h e 7 dias do pós-operatório. A regeneração do órgão foi avaliada quanto ao peso e histologia, sendo esta última por hematoxilina-eosina e antígeno nuclear de proliferação celular. Resultados: A média dos pesos dos animais dos grupos ATX 7 dias e CT 7 dias no pré-operatório foram de 411,2 g e 432,7 g, respectivamente, e após a regeneração foram de 371,3 g e 392,9 g. As médias das taxas de mitose coradas por HE dos dois grupos em 7 dias foram de 33,7 e 32,6 mitoses, respectivamente, e de 14,5 e 14,9 mitoses para os grupos ATX e CT 32 h. A contagem de células por antígeno nuclear de proliferação celular mostrou valores de 849,7 para o grupo ATX 7 dias e 301,8 para o CT 7 dias; 814,2 para o grupo ATX 32 h e 848,1 para o CT 32 h. Conclusão: O ácido tranexâmico mostrou-se efetivo na regeneração hepática somente em período mais longo de observação após hepatectomia parcial.

ABSTRACT Background: Different lesions may affect the liver resulting in harmful stimuli. Some therapeutic procedures to treat those injuries depend on liver regeneration to increase functional capacity of this organ. Aim: Evaluate the effects of tranexamic acid on liver regeneration after partial hepatectomy in rats. Method: 40 rats (Rattus norvegicus albinus, Rodentia mammalia) of Wistar-UP lineage were randomly divided into two groups named control (CT) and tranexamic acid (ATX), with 20 rats in each. Both groups were subdivided, according to liver regeneration time of 32 h or seven days after the rats had been operated. The organ regeneration was evaluated through weight and histology, stained with HE and PCNA. Results: The average animal weight of ATX and CT 7 days groups before surgery were 411.2 g and 432.7 g, and 371.3 g and 392.9 g after the regeneration time, respectively. The average number of mitotic cells stained with HE for the ATX and CT 7 days groups were 33.7 and 32.6 mitosis, and 14.5 and 14.9 for the ATX and CT 32 h groups, respectively. When stained with proliferating cell nuclear antigen, the numbers of mitotic cells counted were 849.7 for the ATX 7 days, 301.8 for the CT 7 days groups, 814.2 for the ATX 32 hand 848.1 for the CT 32 h groups. Conclusion: Tranexamic acid was effective in liver regeneration, but in longer period after partial hepatectomy.

O presente trabalho propõe o uso de modelos de correção de erros para avaliar o comportamento da função de demanda brasileira por arroz em casca e beneficiado entre janeiro de 1995 e junho de 2010. O objetivo geral é testar se os modelos não lineares conseguem representar as relações de curto e longo prazo na demanda. Em geral, os impactos de longo prazo da renda e preço doméstico foram os principais determinantes das importações, com evidências de que o arroz é um bem inferior. O preço de importação contribui menos que proporcionalmente, ao passo que o importador parece ajustar a quantidade importada do período com certo grau de defasagem. A dinâmica de correção do modelo a choques foi atenuada nas estimativas não lineares mensais, enquanto permaneceu praticamente estável nas estimativas trimestrais. Ainda conforme os resultados é possível afirmar que os ciclos de expansão das importações se mostraram fortemente relacionados a eventos climáticos adversos e às alterações da política comercial. Os resultados chamam a atenção para a influência do governo sobre a importação via incentivo tarifário com terceiros - o que se mostra útil para contornar períodos de escassez de oferta do produto no Brasil e no Mercosul.

The objective of this study is to analyze the behavior of the Brazilian demand for rough and milled rice between January 1995 and June 2010. The main aim is to test the adequacy of linear and non-linear relations that represent short and long-term variables on the demand. In general, long-term impacts from income and domestic price were the most determinants to imports and the rice can be seen as an inferior good. The price of imports contributes less than proportionately, while the importer seems to adjust the quantity with some lag. The correction of the model to short-term shocks was eased in monthly non-linear estimates, while it remained nearly stable in quarterly estimates. Finally, one can say that import cycles were strongly related to adverse climatic events, as well as to alterations in trade policy. The results draw attention to the influence of the government on the imports through pricing incentives to third parties - what proves to be helpful to overcome supply shortages in Brazil and Mercosur.

Esse artigo tem dois principais objetivos. Primeiro compara três diferentes técnicas de datação de ciclos para determinar os picos e os vales da produção industrial do Rio Grande do Sul. Os resultados apontaram que, entre 1991-I e 2008-IV, o setor no Estado passou por cinco recessões. Duas tiveram curta duração, de quatro trimestres, e estão associadas a uma taxa de câmbio mais valorizada. Dois outros ciclos recessivos ocorreram em uma conjuntura de crises internacionais. Por fim, a mais longa recessão, que durou oito trimestres, teve como vetor a estiagem que atingiu o Estado. Um segundo objetivo é a determinação de indicadores antecedentes da produção industrial gaúcha. Partindo de mais de 200 séries candidatas, encontra-se que quatro conseguem antecipar a dinâmica cíclica do setor.

This article has two principal goals. First, it compares three different techniques for dating cycles to determine peaks and through of industrial production in the state of Rio Grande do Sul. The results show that between 1991-I and 2008-IV, this sector of the economy underwent five recessions. Two of these were short, lasting four quarters, and are associated with a higher exchange rate. Two other recessives cycles occurred in scenarios of international crises. Finally, the longest recession, lasting eight quarters, was related to the drought that affected the State in 2005. A second objective is the determination of leading indicators of industrial production. Starting with more than 200 series, we found that four are associated with cyclical periods.

O objetivo deste artigo é aplicar o mecanismo de correção de erros linear e não linear para encontrar as elasticidades de resposta das exportações do setor de borracha a diversas variáveis. Duas importantes contribuições emergem desta pesquisa. A primeira é o uso da metodologia de mudança de regime markoviano. A segunda está relacionada aos resultados para o setor. Para a curva de oferta, não é possível afirmar a existência do efeito J. Há evidência de assimetria de desempenho entre regimes de queda e crescimento da demanda por exportações, bem como entre a duração desses estados. Isso pode estar refletindo a influência das elasticidades de curto prazo, em especial no caso da renda e dos preços. De forma geral, os resultados apontam que choques negativos têm muito mais poder de desestabilizar o comportamento das exportações do setor no Brasil que choques positivos.

The goal of this paper is to apply the linear and nonlinear error correction model to supply and demand for rubber exports and find elasticities to several variables. Two major contributions emerge from this research. The first is the use of the methodology of Markovian Switching model. The second is related to the results for the sector. For the supply curve is not possible to affirm the existence of the J effect. There is evidence of asymmetry in performance between states of retraction and growth in demand for exports, as well as between the duration of these states. This may reflect the influence of short-term elasticities, particularly in the case of income and prices. Overall, the results show that negative shocks have much more power to destabilize the exports sector in Brazil than positive shocks.

Este artigo utiliza o modelo de fator dinâmico de Stock e Watson para construir um índice coincidente que tenha um fundamento estatístico claro e que possa ser representativo do nível de atividade da indústria de transformação do Rio Grande do Sul. Além deste modelo linear, também é aplicada a metodologia de mudança de regime para caracterizar a assimetria no ciclo dos negócios na indústria do Estado, indicando os momentos de crescimento e queda na atividade econômica do setor com características diferenciadas. Este novo indicador é comparado com o índice de desempenho industrial (IDI) elaborado pela Federação das Indústrias do Estado do Rio Grande do Sul. Os resultados mostram que tanto o modelo linear quanto o não-linear estimam componentes que são altamente correlacionados como o índice de médias ponderadas atualmente calculado pela FIERGS.

The present article uses the dynamic factor model of Stock and Watson to construct a coincident index with a clear statistical foundation able to represent the level of activity of the processing industry of the state of Rio Grande do Sul. In addition to this linear model, we also employ a regime switching methodology in order to determine the asymmetry of the business cycle in the industry on a statewide basis, pointing out periods of economic growth and stagnation in this sector. This new indicator is compared with the industrial performance index developed by the Federation of the Industries of the State of Rio Grande do Sul (FIERGS). The results show that both linear and nonlinear models estimate components that are highly correlated, such as the weighted average index currently calculated by FIERGS.

Este artigo procura aplicar o método de quase-máxima verossimilhança para estimar a volatilidade estocástica multivariada não-estacionária dos preços de compra dos par bonds de quatro países latino-americanos - México, Brasil, Argentina e Venezuela - no período de 9-8-1994 a 15-9-1999. O objetivo é analisar possíveis movimentos comuns nestas variâncias. Os testes feitos revelam que a volatilidade nos modelos univariados não apresentam inclinação, mas possuem alta persistência. A formulação multivariada relaciona bem os dados, obtendo estimativas consistentes e revelando a existência de um comportamento ao longo do tempo similar entre as volatilidades das quatro séries.

This paper uses a quasi-maximum likelihood procedure to estimate the non-stationary stochastic volatility for the par bonds of four Latin American countries: Brazil, Argentina, Mexico and Venezuela. The aim is to investigate the possible presence of co-movements in volatility across countries. The estimation period goes from August 1994 to September 1999, including, therefore, the Asian and Russian crises. The estimated volatility for the univariate model does not show any slope and is highly persistent. The multivariate model gives a good fit to the data and shows that there is common movement.