Dynamic Bayesian smooth transition autoregressive (DBSTAR) models for non-stationary nonlinear time series

In this thesis, Dynamic Bayesian Smooth Transition Autoregressive (DBSTAR) models are proposed for nonlinear time series, as an alternative to both the classical Smooth Transition Autoregressive (STAR) models and Computational Bayesian STAR (CBSTAR) models. DBSTAR models are autoregressive formulations of dynamic linear models based on polynomial approximations of transition functions of STAR models. Unlike classical STAR and CBSTAR models, their parameters vary in time, being suitable for modelling both global and local non-stationary processes. Since DBSTAR models are Bayesian, the models do not require extensive historical data for parametric estimation and allow expert intervention via prior distribution assessment of model parameters. Because they are analytical and sequential, DBSTAR models, respectively, avoid potential computational problems associated with CBSTAR models, such as convergence issues, and allow fast estimation of dynamic parameters sequentially in time, being thus suitable for real time applications. Proposed DBSTAR models have been applied to two data sets: the much used Canadian Lynx data set, in which the aim is to validate DBSTAR models by comparing their fitting performances with existing approaches in the literature, and a Brazilian electricity load data set, for which existing models are not suitable

A competitividade das centrais de negócios de supermercados independentes: um estudo de caso da rede litoral de supermercados

Os pequenos e médios supermercados de bairro são um importante segmento da economia brasileira e, portanto, da Região Metropolitana da Baixada Santista. Este estudo analisa como pequenas empresas varejistas sobrevivem no mercado por meio de uma Central de Negócios: a Rede Litoral. Aborda os fatores de competitividade dos supermercados independentes por meio do modelo das cinco forças e desenvolve o estudo de caso da Rede Litoral. Identifica-se nessa associação um importante instrumento de competitividade para os supermercados independentes com a economia de escala e escopo que proporciona. E pelo associativismo transformar-se em fonte de vantagem competitiva ao superar as deficiências individuais de cada um

ENSAIO SOBRE O MICROCRÉDITO E AS METODOLOGIAS DE ANÁLISE DE CRÉDITO: ASPECTOS RELACIONADOS À SUA ORIGEM, DESENVOLVIMENTO E O MODELO DE ESCORAGEM COMPORTAMENTAL – BEHAVIOURAL SCORING

The propose of this essay is an overview and approach about microcredit, as a method of granting credit lines and small loans to microentrepreneurs and small groups under to the margin of the traditional financial system, because there is no collateral or assets required in traditional loans. Initially, the theoretical discussion analyzes the aspects of the first experience with microcredit, its development and expansion into other markets, especially Brazil. Also, it is analyzed a financial inclusion tool for low-income promoted by the federal government of the country, aiming to produce social equity, income generation, job families and microentrepreneurs. Extends to the test approach to an understanding of the features and products that are related to microcredit operations, including the methodologies of credit analysis, especially the behavioral scoring model called Behavioural Scoring as a tool for analysis credit to the institutions that run this type of business, the main feature of its structure is the absence of historical and real guarantees for lending.Este ensaio propõe uma abordagem a respeito do microcrédito enquanto modalidade de crédito e concessão de empréstimos de pequena monta para microempreendedores e pequenos grupos de pessoas que são considerados carentes e a margem do sistema financeiro tradicional, pois, usualmente, não apresentam garantias reais por não possuírem os ativos necessários exigidos nas operações tradicionais de empréstimos. Inicialmente, a discussão teórica procura analisar os aspectos que estão associados à primeira experiência com o microcrédito, seu desenvolvimento e expansão para outros mercados em especial o Brasil e o uso como instrumento de inclusão financeira da população de baixa renda fomentada pelo governo federal do país, tendo como objetivo produzir equidade social, geração de renda e trabalho às famílias e aos microempreendedores. Amplia-se a abordagem do ensaio para um entendimento das características e produtos que estão relacionados às operações de microcrédito, incluindo-se ainda as metodologias de análise de crédito, em especial o modelo de escoragem comportamental denominada de Behavioural Scoring, como ferramenta para análise de concessão de crédito para as instituições que fazem este tipo de operação, cuja principal característica de sua estrutura é a ausência de garantias reais para a concessão de crédito e de histórico

Práticas do disclosure voluntário socioambiental em cooperativas agropecuárias brasileiras

The objective of this article is to describe the voluntary disclosure of socio-environmental practices in Brazilian agricultural cooperatives. In order to reach the outlined objective, we analysed the annual reports on the websites of a non-probabilistic sample of the largest Brazilian agricultural cooperatives, referring to the period of 2015. For data analysis, the averages by subcategory and three indices of disclosure rate were used: Disclosure Index (DI), Business Disclosure Index (SDI) and General Business Disclosure Index (IGDE), General Index of Social Disclosure (IGDs). In addition, a fifth disclosure index was developed: the General Index of Environmental Disclosure (IGDa). The results obtained allow us to affirm that there is more disclosure of social information than environmental information, especially in relation to employees, concerns with the community and education, and that there is still a long way to go regarding good socio-environmental voluntary disclosure of agricultural and livestock cooperatives.O objetivo deste artigo é descrever o disclosure voluntário socioambiental em cooperativas agropecuárias brasileiras. A fim de atingir o objetivo traçado, foram analisados os relatórios anuais presentes nos websites de uma amostra não-probabilística das maiores cooperativas agropecuárias brasileiras, referentes ao período de 2015. Para a análise dos dados, foram utilizadas as médias por subcategoria e três índices de avalição de disclosure: Índice de Disclosure (ID), Índice de Disclosure das Empresas (IDE) e Índice Geral de Disclosure das Empresas (IGDE), Índice Geral de Disclosure social (IGDs). Além disso, foi desenvolvido um quinto índice de avaliação do disclosure: o Índice Geral de Disclosure ambiental (IGDa). Os resultados obtidos permitem afirmar que há mais divulgações de informações sociais do que ambientais, com destaque para, relação com empregados, preocupação com a comunidade e com educação, e que ainda falta muito para alcançar uma boa aderência de disclosure voluntário socioambiental pelas cooperativas agropecuárias analisadas

A importância da determinação do espectro da radiação local para um correto dimensionamento das tecnologias de conversão

Este trabalho apresenta uma proposta para determinar uma eficiência de conversão de um dispositivo fotovoltaico baseada não no espectro padrão, mas sim em um espectro alternativo. Este espectro, típico do local de instalação do sistema fotovoltaico, é gerado pelo software SMARTS a partir de dados como temperatura ambiente, pressão atmosférica e latitude. Através da determinação do espectro alternativo e da resposta espectral da tecnologia fotovoltaica a ser analisada, é possível determinar um fator de descasamento espectral. Através deste é possível calcular uma eficiência de conversão para um dispositivo fotovoltaico que se aproxime mais da real eficiência que o dispositivo terá em campo do que fazendo a mesma análise com o espectro padrão. Neste trabalho a metodologia proposta foi testada para a cidade de Farroupilha-RS, Brasil e para as duas tecnologias mais comuns no mercado. Encontrou-se valores de eficiência de 4,7% (m-Si) e 4,8% (mc-Si) superiores às eficiências no espectro padrão.This paper presents a proposal to determine a conversion efficiency of a photovoltaic device based not on the standard spectrum, but in an alternative spectrum. This spectrum, characteristic of the site of the photovoltaic system, is generated by software SMARTS from data such environmental temperature, atmospheric pressure and latitude. By determining of the alternative spectrum and the spectral response of the PV technology to be analyzed it, is possible to determine a spectral mismatch factor. By this factor, it is calculated a conversion efficiency of a PV device that is closer to the real efficiency the device will have on field. In this work the proposed methodology was tested for the city of Farroupilha-RS, Brazil and for the two more representative PV technologies on the market. It was found an increase of 4.7% (m-Si) e 4.8% (mc-Si) for the conversion efficiency if compared with the efficiency in the standard spectrum.Asociación Argentina de Energías Renovables y Medio Ambiente (ASADES

Standardization of a spinal cord lesion model and neurologic evaluation using mice

OBJECTIVE: To standardize a spinal cord lesion mouse model. METHODS: Thirty BALB/c mice were divided into five groups: four experimental groups and one control group (sham). The experimental groups were subjected to spinal cord lesion by a weight drop from different heights after laminectomy whereas the sham group only underwent laminectomy. Mice were observed for six weeks, and functional behavior scales were applied. The mice were then euthanized, and histological investigations were performed to confirm and score spinal cord lesion. The findings were evaluated to prove whether the method of administering spinal cord lesion was effective and different among the groups. Additionally, we correlated the results of the functional scales with the results from the histology evaluations to identify which scale is more reliable. RESULTS: One mouse presented autophagia, and six mice died during the experiment. Because four of the mice that died were in Group 5, Group 5 was excluded from the study. All the functional scales assessed proved to be significantly different from each other, and mice presented functional evolution during the experiment. Spinal cord lesion was confirmed by histology, and the results showed a high correlation between the Basso, Beattie, Bresnahan Locomotor Rating Scale and the Basso Mouse Scale. The mouse function scale showed a moderate to high correlation with the histological findings, and the horizontal ladder test had a high correlation with neurologic degeneration but no correlation with the other histological parameters evaluated. CONCLUSION: This spinal cord lesion mouse model proved to be effective and reliable with exception of lesions caused by a 10-g drop from 50 mm, which resulted in unacceptable mortality. The Basso, Beattie, Bresnahan Locomotor Rating Scale and Basso Mouse Scale are the most reliable functional assessments, and but the horizontal ladder test is not recommended

Pernambuco Semiarid Native Rhizobial Populations Nitrogen Fixation Potential with Native \u3cem\u3eMacroptilium\u3c/em\u3e

Nitrogen (N) is one of nature´s most abundant elements, accounting for about 78% of the atmospheric gases, but mostly as the inert N2 form. As such it is not directly available to plants, and is relatively scarce in most agroecosystems. Biological nitrogen fixation (BNF) through diazotrophic bacteria represents ca. 63% of the yearly N input in terrestrial ecosystems (Taiz and Zeiger 2004). Legumes which form effective symbiosis with the diazotrophic group of bacteria commonly known as rhizobia, are a very important source of available N. Tropical forage legumes are usually able to nodulate with a diverse population of rhizobia, and may have a relevant contribution to nitrogen availability in pastures (Santos et al. 2003). This diversity may be exploited to find more symbiotically efficient bacterial strains, thereby increasing legume effects on pastures. One way to evaluate this diversity is to isolate strains from different regions, vegetation covers or cultivation systems, and environmental conditions. This practice would potentially lead to a large number of isolates, which would increase the chance of finding some more efficient than those currently available (Chagas Junior et al, 2010). Native legumes, including several species of Macroptilium are an important forage resource in the Brazilian Northeast semiarid, contributing to the quality of ruminant diet, but they are still not well known in regards to their BNF ability. This work evaluated nodulation efficiency of Macroptilium lathyroides when inoculated with Litolic Neossol from eight municipalities of Pernambuco State semiarid

Distributions of trace metals in sediment cores from a hypertrophic reservoir in northeast Brazil

The distributions of Al, Cu, Co, Cr, Fe, Mn, Ni, Pb and Zn were measured in two sediment cores obtained from the Macela Reservoir in Northeast Brazil. Principal component analysis (PCA) clearly separated both the cores and the sections corresponding to different depths. The concentrations of Cu, Cr, Mn and Zn were highest in the upper sections (0-20 cm), and were significantly correlated with the total organic carbon (Corg) content. The concentrations of Co, Pb and Ni were highest in the lower sections (25-45 cm), and showed strong correlations with aluminum. Cu, Cr, Mn and Zn were derived from anthropogenic sources, while Co, Ni and Pb were of natural origin. Toxicity assessment based on the threshold effect level (TEL) and probable effect level (PEL) values listed in the Canadian Sediment Quality Guidelines (SQG) showed that Cu, Pb and Zn rarely cause any adverse effects, while Ni was likely to cause frequent effects in the biota of the reservoir. The toxicity of Cr was uncertain. _________________________________________________________________________________________ RESUMO: As distribuições de Al, Cu, Co, Cr, Fe, Mn, Ni, Pb e Zn foram investigadas em dois sítios de sedimentos do reservatório Macela, Nordeste do Brasil. A análise de componentes principais (PCA) separou nitidamente os sítios de sedimentos coletados e as suas diferentes seções. Cu, Cr, Mn e Zn apresentaram as maiores concentrações nas seções do topo (0-20 cm) e mostraram correlações significativas com o conteúdo de carbono orgânico total (Corg). As concentrações de Co, Pb e Ni foram maiores nas seções do fundo (25-45 cm) e mostraram fortes correlações com alumínio. Cu, Cr, Mn e Zn foram provenientes do aporte antropogênico, enquanto que Co, Ni e Pb foram de origem natural. As toxicidades avaliadas com base nos valores do nível limiar de efeitos (TEL) e nível provável de efeitos (PEL) listados no Sediment Quality Guidelines (SQG) canadense mostraram que Cu, Pb e Zn raramente exercem efeitos adversos aos organismos, enquanto que para o Ni, esses efeitos biológicos ocorrem frequentemente à biota do reservatório. A toxicidade do Cr foi incerta