74 research outputs found

    Modelo de Ritchie: descrição e aplicação.

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    ABSTRACT: Among the several methods used to manage irrigation, the ones based on the calculation of crop water consumption or evapotranspiration are the most common. From those, the one presented by Doorenbos e Pruitt (1977) is the most used. Based on this method, the crop evapotranspiration is calculated multiplying a crop reference evapotranspiration by a crop coefficient. Applying this methodology in some situations is not convenient, for instance, in the estimative of crop water use efficiency. Besides of this, a good estimative of crop coefficient is difficult and should be done for each region, once is site specific. Options to this method are the models that calculate the evaporation and transpiration separately. Among those, the one presented by Ritchie (1972) is the most popular. It was developed to calculate row crop evapotranspiration in situations where neither soil water deficit occur nor crop is in senescence stage. This model has been used successfully to estimate crop evapotranspiration under different climatic, soil and crop conditions. To use this model it is necessary to estimate two soil parameters. Even though the methodology to estimate these two parameters is of easy application. It is not widely known. The objectives of this paper were: i) to describe the Ritchie model and apply it to calculate the evapotranspiration of Cerrados' crop; and ii) to present methodologies to estimate both its soil parameter and the crop leaf are index.bitstream/CPAC-2009/27306/1/doc_133.pd

    Comparative Microsatellite Typing of New World Leishmania infantum Reveals Low Heterogeneity among Populations and Its Recent Old World Origin

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    Leishmania infantum (syn. L. chagasi) is the causative agent of visceral leishmaniasis (VL) in the New World (NW) with endemic regions extending from southern USA to northern Argentina. The two hypotheses about the origin of VL in the NW suggest (1) recent importation of L. infantum from the Old World (OW), or (2) an indigenous origin and a distinct taxonomic rank for the NW parasite. Multilocus microsatellite typing was applied in a survey of 98 L. infantum isolates from different NW foci. The microsatellite profiles obtained were compared to those of 308 L. infantum and 20 L. donovani strains from OW countries previously assigned to well-defined populations. Two main populations were identified for both NW and OW L. infantum. Most of the NW strains belonged to population 1, which corresponded to the OW MON-1 population. However, the NW population was much more homogeneous. A second, more heterogeneous, population comprised most Caribbean strains and corresponded to the OW non-MON-1 population. All Brazilian L. infantum strains belonged to population 1, although they represented 61% of the sample and originated from 9 states. Population analysis including the OW L. infantum populations indicated that the NW strains were more similar to MON-1 and non-MON-1 sub-populations of L. infantum from southwest Europe, than to any other OW sub-population. Moreover, similarity between NW and Southwest European L. infantum was higher than between OW L. infantum from distinct parts of the Mediterranean region, Middle East and Central Asia. No correlation was found between NW L. infantum genotypes and clinical picture or host background. This study represents the first continent-wide analysis of NW L. infantum population structure. It confirmed that the agent of VL in the NW is L. infantum and that the parasite has been recently imported multiple times to the NW from southwest Europe

    Microbiological quality in the flour and starch cassava processing in traditional and model unit

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    O objetivo deste trabalho foi avaliar a qualidade microbiolĂłgica de farinha e fĂ©cula durante as diferentes etapas do processamento de mandioca, em unidades tradicionais e em uma unidade modelo. Foram determinados Ă­ndices de coliformes totais e termotolerantes, Bacillus cereus, Salmonela spp., bactĂ©rias e fungos nas farinhas e fĂ©culas. NĂŁo foram observadas presenças de B. cereus e Salmonella spp. na farinha e fĂ©cula de mandioca produzidas nas unidades estudadas. A incidĂȘncia microbiana diminui com o avanço da etapa do processamento para obtenção de farinha e foi menor na unidade modelo. ApĂłs o processo de torra, a carga microbiana estava de acordo com os valores preconizados pela legislação brasileira, concluindo-se que essa etapa pode ser considerada como crĂ­tica na obtenção de farinha. Na obtenção de fĂ©cula, a carga microbiana nas unidades tradicionais sĂŁo maiores que na modelo, e o aumento do nĂșmero de extraçÔes promove o aumento da incidĂȘncia de microrganismos, sendo recomendadas apenas quatro extraçÔes. ______________________________________________________________________________________ ABSTRACT: The objective of this research was to evaluate microbiological contamination in the flour and starch during cassava processing in traditional and model units. The total and fecal coliforms indexes, Bacillus cereus, Salmonella, bacteria, yeast and fungi were determined. Bacillus cereus and Salmonella were not detected in any sample. The incidence of microorganisms decreased along the processing to obtain cassava flour, and is lower in model unit. After the roasting process, the microbial load was below the values established by the Brazilian legislation, and can be regarded as a critical step in obtaining cassava flour. Concerning starch production, the microbial load in the traditional units was higher than in the model units, and the increase of the extraction steps has promoted the growth of microorganisms. It’s recommended the used of only 4 extractions

    A historical overview of the classification, evolution, and dispersion of Leishmania parasites and sandflies

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    Background The aim of this study is to describe the major evolutionary historical events among Leishmania, sandflies, and the associated animal reservoirs in detail, in accordance with the geographical evolution of the Earth, which has not been previously discussed on a large scale. Methodology and Principal Findings Leishmania and sandfly classification has always been a controversial matter, and the increasing number of species currently described further complicates this issue. Despite several hypotheses on the origin, evolution, and distribution of Leishmania and sandflies in the Old and New World, no consistent agreement exists regarding dissemination of the actors that play roles in leishmaniasis. For this purpose, we present here three centuries of research on sandflies and Leishmania descriptions, as well as a complete description of Leishmania and sandfly fossils and the emergence date of each Leishmania and sandfly group during different geographical periods, from 550 million years ago until now. We discuss critically the different approaches that were used for Leishmana and sandfly classification and their synonymies, proposing an updated classification for each species of Leishmania and sandfly. We update information on the current distribution and dispersion of different species of Leishmania (53), sandflies (more than 800 at genus or subgenus level), and animal reservoirs in each of the following geographical ecozones: Palearctic, Nearctic, Neotropic, Afrotropical, Oriental, Malagasy, and Australian. We propose an updated list of the potential and proven sandfly vectors for each Leishmania species in the Old and New World. Finally, we address a classical question about digenetic Leishmania evolution: which was the first host, a vertebrate or an invertebrate? Conclusions and Significance We propose an updated view of events that have played important roles in the geographical dispersion of sandflies, in relation to both the Leishmania species they transmit and the animal reservoirs of the parasites
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