486 research outputs found
GESTÃO DO RISCO DO PREÇO DO AÇÚCAR PARA OS PRINCIPAIS ESTADOS PRODUTORES BRASILEIROS NO MERCADO FUTURO DA BM&FBOVESPA
ResumoAo digladiar pelo espaço em produção, o açúcar e o etanol, acabam por incorporar um componente de incerteza quanto aos preços, principalmente por afetar as condições de oferta relacionadas aos mesmos. Neste contexto, percebe-se a importância de estratégias de proteção que contribuam para o gerenciamento do risco do preço da commodity do açúcar, e que englobem negociações formais de compra e venda através de contratos padronizados, por preços futuros pré-estabelecidos e com vencimento em data já pré-determinada. Assim sendo, este estudo teve como objetivo principal verificar a efetividade das operações de hedge do açúcar na BM&F Bovespa para os estados de São Paulo, Minas Gerais, Alagoas e Pernambuco. A fundamentação teórica baseou-se em estudos referentes à comercialização agrícola e à análise da efetividade do mercado futuro no gerenciamento do risco de preços das commodities agropecuárias no Brasil. Para os testes empíricos foram utilizadas séries temporais de preços futuros e a vista (médias mensais), referente são período de novembro de 2007 a agosto de 2014. O estudo caracteriza-se como descritivo do tipo quantitativo, e compreende especificamente, verificação da estatística descritiva dos preços, cálculo da base e risco de base, estimação da razão e efetividade de hedging de pela aplicação do modelo de Myers e Thompson (1989). Os resultados apontaram que o mercado futuro do açúcar é efetivo na mitigação do risco de preços dos mercados a vista do açúcar apenas para os estados de São Paulo e Minas Gerais.Palavras-chave: Comercialização Agrícola; Commodities Agrícolas; Hedge
Internal loading potential of phosphorus in reservoirs along a semiarid watershed.
All rights reserved. Sediments are important to nutrient dynamics, especially due to phosphorus internal loading. Several studies have observed that internal loading could prevent water quality from improving in lakes, even when external phosphorus loading is significantly decreased. Therefore, there is an urgent need to assess the potential release of phosphorus contained in the sediment, and thus, its potential to impact water quality. In this study, the vertical and horizontal distributions of distinct phosphorus forms in the bottom sediments of artificial reservoirs, located at Forquilha watershed (Ceará, Brazil), were investigated through sequential chemical fractionation. The reservoirs Lagoa Cercada (R#1), Riacho do Algodão (R#2), Riacho Verde (R#3), Cachoeira (R#4), Chagas Manu (R#5), Quandu (R#6) and Balanças (R#7) were investigated. Reservoirs R#1 (most downstream reservoir of the watershed) and R#7 (most upstream reservoir of the watershed) had higher concentrations of total phosphorus (PT) and lower pH values, potentially exerting greater influence in phosphorus concentration in the water column. Reservoirs R#3 and R#4 presented a predominance of residual phosphorus (PRe), the least available fractions of phosphorus and thus, presented a lower potential for internal loading. Reservoirs R#5, R#1 and R#2 showed a tendency of decreasing total phosphorus (PT) as the sediment depth increased, probably indicating an increase of allochthonous phosphorus loading along time. Reservoir R#6 showed the predominance of PFeAl and PCa fractions on points A and B, respectively, showing that the characteristics of the sediments may vary in the same reservoir. Mobile (PM) and iron and aluminum-bound phosphorus (PFeAl) were the least and the most abundant fractions in most of the samples analyzed, respectively
Avaliação financeira de projeto de investimento em pinhão manso
O pinhão-manso aparece no cenário atual como uma oleaginosa promissora para o desenvolvimento da cadeia produtiva do biodiesel sem competir com fontes de alimentação humana ou animal. Devido aos relatos de bom desempenho desta cultura em locais de baixa umidade, seria uma alternativa para as regiões mais secas do país. No presente estudo, utilizou-se de conceitos de análise financeira de projetos, ferramentas de contabilidade, economia e agronomia para verificar a viabilidade financeira do plantio de pinhão-manso, em lavoura de sequeiro, no Semi-Árido baiano para produção de biodiesel. O levantamento das condições edafoclimáticas4 foi realizado em uma propriedade rural do município de Vitória da Conquista-BA (estudo de caso), região localizada na delimitação do Semi-Árido baiano. O principal objetivo é gerar informações que auxiliarão o produtor na tomada de decisão de investimentos. Assim sendo, são apresentados os indicadores de rentabilidade simples, tempo de retorno do investimento, taxa interna de retorno, valor presente líquido, índice de lucratividade, ponto de equilíbrio e análise de sensibilidade. Os resultados apontaram que, nas condições estudadas, o investimento é recomendado quando houver a possibilidade de comercialização dos co-produtos
Serosurvey of Smooth Brucella, Leptospira spp. and Toxoplasma gondii in Free-Ranging Jaguars (Panthera onca) and Domestic Animals from Brazil.
This study investigated the exposure of jaguar populations and domestic animals to smooth Brucella, Leptospira spp. and Toxoplasma gondii in the Cerrado, Pantanal and Amazon biomes of Brazil. Between February 2000 and January 2010, serum samples from 31 jaguars (Panthera onca), 1,245 cattle (Bos taurus), 168 domestic dogs (Canis lupus familiaris) and 29 domestic cats (Felis catus) were collected and analysed by rose bengal test for smooth Brucella, microscopic agglutination test for Leptospira spp. and modified agglutination test for T. gondii. Cattle populations from all sites (9.88%) were exposed to smooth Brucella, but only one jaguar from Cerrado was exposed to this agent. Jaguars captured in the Cerrado (60.0%) and in the Pantanal (45.5%) were seropositive for different serovars of Leptospira spp., cattle (72.18%) and domestic dogs (13.1%) from the three sites and one domestic cat from Pantanal were also seropositive for the agent. The most prevalent serotype of Leptospira spp. identified in jaguars from the Cerrado (Grippotyphosa) and the Pantanal (Pomona) biomes were distinct from those found in the domestic animals sampled. Jaguars (100%), domestic dogs (38.28%) and domestic cats (82.76%) from the three areas were exposed to T. gondii. Our results show that brucellosis and leptospirosis could have been transmitted to jaguars by domestic animals; and jaguars probably play an important role in the maintenance of T. gondii in nature
Nutrient extraction and export by fully irrigated sugarcane varieties
A pesquisa tecnológica para suporte do setor sucroalcooleiro nacional mostra que são esporádicos os trabalhos desenvolvidos com cana-de-açúcar irrigada envolvendo a exigência nutricional. Nesse contexto, objetivou-se quantificar, durante o ciclo de cana-planta de 11 variedades de cana-de-açúcar (SP79-1011, RB813804, RB863129, RB872552, RB943365, RB72454, RB763710, SP78-4764, SP81-3250, RB867515 e RB92579) cultivadas sob irrigação plena, a capacidade de extração e exportação de N, P, K, Ca e Mg, bem como a exigência nutricional para produção de uma tonelada de colmo por hectare (TCH). A pesquisa foi realizada em campo, no município de Carpina, PE, durante a safra agrícola 2006/2007. O delineamento experimental empregado foi de blocos casualizados, com 11 tratamentos e quatro repetições. A extração e exportação de nutrientes, assim como a exigência nutricional, foram avaliadas aos 360 dias após o plantio (DAP) na parte aérea das plantas. A extração de nutrientes na parte aérea da cana-planta apresentou, em média, valores de 179, 25, 325, 226 e 87 kg ha-1 de N, P, K, Ca e Mg, respectivamente, o que proporcionou a seguinte ordem decrescente de extração: K > Ca > N > Mg > P. A exportação média de N, P, K, Ca e Mg pelo colmo das variedades irrigadas foi de 92; 15; 188; 187; e 66 kg ha-1; correspondendo, respectivamente, a 51, 60, 58, 83 e 76 % de todo o nutriente extraído na parte aérea da cana-planta, com destaque para as variedades RB92579 e SP81-3250 para o N, RB813804, RB863129, RB872552, RB763710, RB92579, SP78-4764, SP81-3250 e SP79-1011 para o P, SP79-1011, SP81-3250, RB813804, RB872552 e RB763710 para o K, RB92579 e RB863129 para o Ca e RB92579 para o Mg. Para produção de uma TCH, foram exigidos pelas variedades durante o ciclo de cana-planta valores médios de 0,91; 0,13; 1,71; 1,18; e 0,44 kg de N, P, K, Ca e Mg, respectivamente.A review of technology research supporting the Brazilian sugaralcohol sector shows that only sporadic studies with irrigated sugarcane have been developed to investigate nutritional requirements. In this context, the objective of this study was to quantify the capacity of extraction and export of N, P, K, Ca, and Mg as well as the nutritional requirement for the production of one ton of stalk per hectare (TCH) in the plant cane cycle of 11 sugarcane varieties (SP79-1011, RB813804, RB863129, RB872552, RB943365, RB72454, RB763710, SP78-4764, SP81-3250, RB867515, and RB92579) grown under full irrigation. The research was conducted under field conditions in the municipality of Carpina, PE, in the 2006/2007 growing season. The experiment was arranged in a randomized block design with 11 treatments and four replications. Nutrient extraction and export as well as nutritional requirements of the shoot components of the plants were evaluated 360 days after planting. The mean nutrient accumulation in shoots was 179, 25, 325, 226, and 87 kg ha-1 of N, P, K, Ca, and Mg, respectively.The average export of N, P, K, Ca, and Mg via stalks of the irrigated varieties was 92, 15, 188, 187, and 66 kg ha-1; corresponding, respectively, to 51, 60, 58, 83, and 76 % of the whole nutrient amount taken up by the cane plant. The extracted nutrient amounts were highest by the following varieties: RB92579 and SP81-3250 for N; RB813804, RB863129, RB872552, RB763710, RB92579 SP78-4764, SP81-3250 and SP79-1011 for P; SP79-1011, SP81-3250, RB813804, RB872552 and RB763710 for K; RB92579 and RB863129 for Ca; and RB92579 for Mg, for which the export values in stalks were highest. For the production of one TCH, the varieties needed 0.91, 0.13, 1.71, 1.18, and 0.44 kg of N, P, K, Ca, and Mg, respectively
Alien spiders: First record of Loxosceles gaucho Gertsch, 1967 (Araneae: Sicariidae) in the Amazon region, Brazil
We present the first record for Loxosceles gaucho Gertsch, 1967 in the Amazonian region of Brazil. Four males, fifteen females and forty-nine immatures were collected in different places in Manaus, Amazonas, Brazil. This is the third species of Loxosceles reported in the Amazon region along with L. amazonica Gertsch, 1967, and L. similis Moenkhaus, 1898. This is the first record of an invasive species of a venomous animal in the state of Amazonas, Brazil, which is noteworthy due to its synanthropic habit, which increases the risk to the local population
O professor na trajetória do aluno como referência ou cicatriz: entrevista com Diógenes de Castro
The Didactic Contract from the Perspective of the Theory of Didactical Situations: An Integrative Review
The phenomena related to the mathematical teaching and learning process have a significant and direct influence on the construction of knowledge and studying these issues is of interest to the theory developed by Guy Brousseau, called Theory of Didactical Situations. When dealing with the relations established between student, knowledge and teacher, Brousseau presents those that are specific, explicitly and implicitly, of the relationship between teacher and students, as well as their influences on the teaching and learning process, defining, for this, the Didactic Contract, which consists of the set of behaviors that the teacher expects from the student and the student from the teacher. With this, the following question arose for this work: What is the relevance of the Didactic Contract when designing teaching sequences with input in the Theory of Didactical Situations? The objective was, then, to carry out an integrative review in order to systematize information present in scientific articles about the Didactic Contract in the perspective of the Theory of Didactical Situations. A search for works was carried out in the databases Scielo, Google Scholar and Portal de Periódicos CAPES/MEC through the descriptors "Didactic Contract" and "Theory of Didactical Situations", with the following exclusion criteria: works not related to the theme and book, theses, dissertations and monographs. That is, only papers of the scientific article type were chosen. A total of one hundred and seventy-seven works were obtained as an initial result, of which thirteen were repeated. After reading the abstracts and adopting the exclusion criteria, sixteen articles remained, of which nine responded to the elaborated question. With the research, it was found, in the period consulted, a limitation of publications that deal specifically with the Didactic Contract and, in spite of that, it was concluded that the Didactic Contract is a very important element in a teaching and learning situation, because it can favor or cause an obstacle in the acquisition of new knowledge by the student
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