ANÁLISE DA VOLATILIDADE DOS PREÇOS DE BOI GORDO NO ESTADO DE SÃO PAULO: UMA APLICAÇÃO DOS MODELOS GARCH

O presente trabalho teve como objetivo realizar uma análise da volatilidade do retorno dos preços de boi gordo no Estado de São Paulo; examinando-se dois fatores determinantes, a persistência de choques e assimetrias na volatilidade, por meio da aplicação dos modelos ARCH/GARCH. Os resultados empíricos mostraram reações de persistência e assimetria na volatilidade, ou seja, os choques negativos e positivos têm impactos diferenciados sobre a volatilidade dos retornos dos preços do boi gordo, o que pode ser comprovado pelos modelos EGARCH e TARCH.--------------------------------------------- This paper aims to analyze the volatility process of the return the prices of beef cattle in the State of São Paulo; examining two factors determinatives, the persistence of shocks and asymmetry in the volatility, by means of the application of ARCH/GARCH models. The empirical results had shown persistence reactions and asymmetry in the volatility, that is, the negative and positive shocks have impacts differentiated on the volatility of the returns of the prices of beef cattle, what it can be proven by EGARCH and TARCH models.boi gordo, volatilidade, assimetria, modelos ARCH/GARCH, beef cattle, volatility, asymmetry, ARCH/GARCH models, Livestock Production/Industries,

SARS-CoV-2-induced amyloidgenesis : not one, but three hypotheses for cerebral COVID-19 outcomes

The main neuropathological feature of Alzheimer’s disease (AD) is extracellular amyloid deposition in senile plaques, resulting from an imbalance between the production and clearance of amyloid beta peptides. Amyloid deposition is also found around cerebral blood vessels, termed cerebral amyloid angiopathy (CAA), in 90% of AD cases. Although the relationship between these two amyloid disorders is obvious, this does not make CAA a characteristic of AD, as 40% of the non-demented population presents this derangement. AD is predominantly sporadic; therefore, many factors contribute to its genesis. Herein, the starting point for discussion is the COVID-19 pandemic that we are experiencing and how SARS-CoV-2 may be able to, both directly and indirectly, contribute to CAA, with consequences for the outcome and extent of the disease. We highlight the role of astrocytes and endothelial cells in the process of amyloidgenesis, as well as the role of other amyloidgenic proteins, such as fibrinogen and serum amyloid A protein, in addition to the neuronal amyloid precursor protein. We discuss three independent hypotheses that complement each other to explain the cerebrovascular amyloidgenesis that may underlie long-term COVID-19 and new cases of dementia

Análise de conteúdo e análise de discurso nas ciências sociais

Transforming collected raw-state data into research results involves the use of certain precedures so as to systematize, categorize and enable its analysis by the researcher.In the specific case of the analysis of communications, adequate mechanisms are demanded so one is able to find in data obtained by means of interviews, messages and documents in general information that illustrate, explain or help bring investigated phenomena to light. Among such mechanisms are the analysis of contents and the analysis of speech as theorical-methodological propositions, intending to surpass their status as “simple techniques of analysis†and compose a field of knowledge. Thus, this present text has been elaborated aiming to providing a better understanding about what constitutes the contents and speech analyses, so as to providing researchers with some subsidy for their adequate utilization. For such, the authors intended to approach these two fields of knowledge, primarily giving their definition, contextualizing them and reporting their historical origins. Next, the authors sought to dealing with each one’s utilization, operationalization and organization, as well as with their specificities. Later, some comparisons between the analisys of contents and the analysis of speech were elaborated, aiming to facilitate the reader’s understanding. Last, some final considerations were woven which deal with the limitations of this work in the sense of trying to approach, in a short essay, two areas of knowledge about which a vast amplitude of studies, publishings and research already exist.analysis of contents, analysis of speech, social sciences,

INADIMPLÊNCIA NO CRÉDITO AGRÍCOLA – UMA APLICAÇÃO DO MODELO DE REGRESSÃO LOGÍSTICA

O objetivo deste artigo é estudar as características dos tomadores e avaliar a possibilidade de prever a inadimplência para a carteira de crédito de uma cooperativa da região Noroeste do Paraná, com dados da safra 2006/2007. O perfil dos tomadores de crédito descrito no trabalho mostrou que os maiores percentuais de inadimplência estão na cultura da laranja e com contratos entre dez e cinqüenta mil reais, porém não apresenta uma característica padrão que permita considerar de antemão os tomadores como adimplentes ou inadimplentes. O modelo de regressão logística construído conseguiu prever de forma eficiente a inadimplência da carteira, porém também considerou inadimplente grande parte dos adimplentes. Isso torna sua utilização economicamente inviável, já que o custo de negar crédito para os adimplentes previstos pelo modelo como inadimplentes é maior que liberar crédito para todos os inadimplentes da carteira. De qualquer forma, os resultados contribuem para a construção de modelos posteriores que, ao incorporar outras variáveis possam melhorar a compreensão do problema de assimetria de informação entre tomadores e fornecedores de crédito.---------------------------------------------The objective of this study is to build a model that can reduce the information asymmetry between the principal and the agent and, thereby, foresee the default in the credit portfolio of a cooperative located in the northwest region of Paraná, with the 2006/2007 harvest data, using the logistics regression model. The credit takers’ profile, described in the present paper, showed that the largest percentage of default was among those who cultivate oranges with contracts of ten to fifty thousand reais, however, there is no such pattern that leads to beforehand considerate those takers as payers or defaulters. The constructed model was efficiently able to anticipate the default of the portfolio, however, it also considered defaulters a great part of the payers, what makes its use economically impracticable, since the cost of denying credit for those payers previously considered by the model as defaulters is higher than liberating credit for all the defaulters of that portfolio. Anyhow, the results contribute to the construction of posterior models that, incorporating other variables, may improve the comprehension about the information asymmetry problem between credit takers and suppliers.Inadimplência, Regressão Logística, Assimetria de Informação, Crédito Rural, Default, logistics regression, information asymmetry, rural credit, Agricultural Finance,

A mudança do regime cambial e o seu impacto na balança comercial brasileira

The purpose of this paper is to evaluate the impact of the change on the Brazilian exchange rate policy implemented in January 1999, and to analyze agricultural sector transformations. Specifically, the paper is an attempt to identify the economic relations of the aggregate performance of the Brazilian commercial trade balance and total GDP or agricultural GDP, world income, and real exchange rate as of in the 1980-2006 (up to first quarter) period. The main conclusion of the study is that the exchange rate policy bands of Plano Real exerted a negative effect on exports and favored imports. With the liberation of the Brazilian exchange rate, from 1999 on, the estimated relations appear to have a positive net effect on the commercial trade balance of the country. But the statistical results of the econometric model are not reliable.Exchange Rate Policy, Commercial Trade Balance, Brazilian Agriculture, International Relations/Trade,

Soil Arthropods in the Douro Demarcated Region Vineyards : General Characteristics and Ecosystem Services Provided

Viticulture is one of the oldest and most profitable forms of agriculture; it is also one of the most intensive farming systems. As intensive cultivation threatens the environment, there is increasing interest in the concept of sustainability within the wine industry, as well as new business opportunities, as customers begin to pay more attention to environmental and sustainability issues. Recognizing the key role of soil quality in environmentally and economically sustainable viticulture makes it essential to understand better soil arthropod communities, given their crucial functions in maintaining soil quality and health. The 'Douro Demarcated Region' (DDR) in northern Portugal offers good potential, in regards to biodiversity, due to its significant areas of non-crop habitats. This work aims to compile information on soil arthropod communities (both soil surface and soil-living) collected in the DDR vineyard agroecosystems. A description of the ecosystem services provided by them, as a basis for the development and implementation of sustainable viticulture systems, is also an objective of this work. An important set of soil arthropods necessary for the delivery of vital ecosystem services for viticulture, with particular reference to supporting and regulating services, occurred in this ecosystem. Eight classes were chiefly represented in a sample of about 167,000 arthropod specimens: Arachnida, Chilopoda, Diplopoda, Entognatha, Insecta, Malacostraca, Pauropoda, and Symphyla. The most representative were Entognatha and Insecta in soil-surface arthropods, and Arachnida and Entognatha in soil-living arthropods. The presence of recognized groups as bioindicators in agroecosystems, such as soil quality indicators, is also revealed. This knowledge is expected to contribute to a more efficient and sustainable management of the viticultural ecosystem.Peer reviewe

Grape juice increases the BDNF levels but not alter the S100B levels in hippocampus and frontal cortex from male Wistar rats

Several studies have shown that a high consumption of vegetables and fruits is consistently associated with a low risk of oxidative stress-induced diseases, which includes some degenerative diseases such as amyotrophic lateral sclerosis, Alzheimer and Parkinson. Therefore, the objective of this study is to verify the effects of conventional and organic grape juice in the modulation of the neurotrophic factor (BDNF) and astrocytic markers protein (S100B) in hippocampus and frontal cortex of Wistar rats. In this study, 24 male Wistar rats were divided into three groups. To the first one, it was given organic purple grape juice; to the second, conventional grape juice, while the last one received only saline. After 30 days, all rats were sacrificed and hippocampus and frontal cortex were dissected. The animals that received organic and conventional grape juice showed, in frontal cortex, an elevated BNDF levels in relation to saline group. However, S100B levels did not change. These results showed that grape juices are able to modulate important marker in brain tissue, and could be an important factor to prevent brain diseases

A New Way to Improve Logistics Efficiency and Aircraft-Onground Recovery

The objective of this project was to bring more efficiency to logistics, improving time of Aircraft-on-Ground (AOG) recovery and developing possible saving for airlines operations. There proposed goal was to develop a system that would allow airlines to easily visualize an available space at the aircraft cargo bay on a desired flight and book its company materials (COMAT) on it, still respecting all appropriate regulation and the final availability of space. This project was inspired by an existing system called MyIDTravel that allows jointed airline’s personnel to buy available tickets with low fares. The objective was to develop something similar for COMAT. The personnel responsible for logistics at jointed airlines would be able to check available cargo bay spaces on the desired flights and book COMAT transportation paying regular prices but having priority over regular cargo. This would enhance the utilization of empty space and optimize the transportation of required material to restore or maintain the airlines operation