2,213 research outputs found

    Análise da intensificação da agricultura no Mato Grosso à partir de dados TRMM 3B42 e de series temporais MODIS/EVI.

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    The Brazilian state of Mato Grosso (southern Amazonia) is one of the main national producer of agricultural products such as soybean, cotton and corn. After having based its development on the expansion of arable lands through deforestation for thrity years, the agricultural sector is now increasing its productive potential through the adoption of new agricultural management practices such as double cropping systems. Remote sensing tehcniques such as classification of MODIS/TERRA EVI times series are efficient tools for monitoring this phenomena. It appears that double cropping systems with wo comercial crops (soybean and corn or soybean and cotton) improved from 6% to 26% of the total cultivated area in Mato Grosso between 2000- 2001 and 2006-2007 harvests. However, when studying at a county level, those rates vary from 1 to more than 50%, attesting that it exists a strong spatial variability concerning the application of this agricultural management practice. It is argued that this rate is in part drove by the importance of total agricultural areas in a place and by pluviometric conditions. This hypothesis is confirmed by crossing MODIS data with rainfall data. These data are issue from the TRMM 3B42 products, which are computed into parameters such as duration, onset, end of the rain season and total annual rainfalls. Those parameters are found to explain 42% of the spatial variability of the application of double cropping systems in Mato Grosso. O objetivo deste artigo é de mapear as áreas cultivadas com duas safras e de estimar se o grau de intensificação encontrado em uma área pode ser relacionado às condições pluviométricas

    Indicadores para a avaliação da disponibilidade hídrica para o desenvolvimento sustentável da atividade canavieira irrigada.

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    Para a racionalização do uso dos recursos hídricos e promoção do desenvolvimento sustentável da atividade canavieira na região Centro-Oeste torna-se importante o desenvolvimento de procedimentos metodológicos que possam fornecer subsídios técnicos para o planejamento e gestão setorial - agricultura e recursos hídricos. O presente trabalho apresenta dois indicadores concebidos para a avaliação do potencial da disponibilidade hídrica para atender a demanda projetada de água para o desenvolvimento da atividade canavieira

    Sistema de indicadores para a avaliação da sustentabilidade hídrica da atividade canaviera.

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    O objetivo deste trabalho é apresentar um estudo de caso realizado na Bacia Hidrográfica do Rio Verde (BHRV) para demonstrar a aplicabilidade do Sistema de Indicadores - SISHidro-Cana - para a avaliação da sustentabilidade hídrica da cultura canavieira, proposta por Ferraz (2012), como uma metodologia para avaliar a disponibilidade de água de bacias hidrográficas para subsidiar a proposição de políticas setoriais, ordenação territorial, planejamento agrícola e gestão dos recursos hídricos

    COMPARAISON DES PRECIPITATIONS PENDANT LA PERIODE DE CULTURE DE SOJA DANS DEUX REGIONS AU BRESIL

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    International audienceThis paper aims to compare the recent rainfall variability during the soybean cultivation month between 1998-1999 and 2012-2013 in two main producing regions in Brazil: the northwestern Rio Grande do Sul and north Mato Grosso. The data correspond to cumulative monthly figures between October and April of the National Water Agency rain gauge network (ANA) in Brazil. The main results indicate annual variability different modes, especially in subtropical and temperate climates such as Rio Grande do Sul that have the observed rainfall lowest variability values indicating greater consistency between data and also a great relationship with soy annual data. In the Mato Grosso region, dominated by the tropical continental climate and also transitional climate, the variability is lower and the relation between annual rainfall and soybean production cannot be stated as simply.Le but de cet article est de comparer la variation récente de l'ensemble des précipitations des mois correspondant à la culture de soja entre 1998-1999 et 2012-2013 dans deux régions productrices au Brésil : le Nord-Ouest du Rio Grande do Sul et le Nord du Mato Grosso. Les données utilisées sont les totaux mensuels cumulés entre octobre et avril, obtenus auprès de l'Agence nationale de l'eau (ANA) du Brésil. Les principaux résultats indiquent différents modes de variabilité interannuelle, en particulier pour les climats subtropicaux et tempérés comme dans l'Etat de Rio Grande do Sul, qui présente la plus faible variabilité pluviométrique observée, ainsi qu'une bonne relation entre les pluies annuelles et les rendements de soja. Dans la région du Mato Grosso, où domine un climat tropical de type continental plus arrosé, la variabilité est moins homogène entre les stations pluviométriques et la relation entre pluies annuelles et rendements du soja ne peut être établie

    Field-oriented assessment of agricultural crops through temporal segmentation of modis VI data.

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    Monitoring agricultural crops constitutes a vital task for the general understanding of land use spatio-temporal dynamics. This paper presents an approach for the enhancement of current crop monitoring capabilities on a regional scale, in order to allow for the analysis of environmental and socio-economic drivers and impacts of agricultural land use. This work discusses the advantages and current limitations of using 250m VI data from the Moderate Resolution Imaging Spectroradiometer (MODIS) for this purpose, with emphasis in the difficulty of correctly analyzing pixels whose temporal responses are disturbed due to certain sources of interference such as mixed or heterogeneous land cover. It is shown that the influence of noisy or disturbed pixels can be minimized, and a much more consistent and useful result can be attained, if individual agricultural fields are identified and each field's pixels are analyzed in a collective manner. As such, a method is proposed that makes use of image segmentation techniques based on MODIS temporal information in order to identify portions of the study area that agree with actual agricultural field borders. The pixels of each portion or segment are then analyzed individually in order to estimate the reliability of the temporal signal observed and the consequent relevance of any estimation of land use from that data. The proposed method was applied in the state of Mato Grosso, in mid-western Brazil, where extensive ground truth data was available. Experiments were carried out using several supervised classification algorithms as well as different subsets of land cover classes, in order to test the methodology in a comprehensive way. Results show that the proposed method is capable of consistently improving classification results not only in terms of overall accuracy but also qualitatively by allowing a better understanding of the land use patterns detected. It thus provides a practical and straightforward procedure for enhancing crop-mapping capabilities using temporal series of moderate resolution remote sensing data

    Detecting outliers and asserting consistency in agriculture ground truth information by using temporal VI data from modis.

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    Collecting ground truth data is an important step to be accomplished before performing a supervised classification. However, its quality depends on human, financial and time ressources. It is then important to apply a validation process to assess the reliability of the acquired data. In this study, agricultural infomation was collected in the Brazilian Amazonian State of Mato Grosso in order to map crop expansion based on MODIS EVI temporal profiles. The field work was carried out through interviews for the years 2005-2006 and 2006-2007. This work presents a methodology to validate the training data quality and determine the optimal sample to be used according to the classifier employed. The technique is based on the detection of outlier pixels for each class and is carried out by computing Mahalanobis distances for each pixel. The higher the distance, the further the pixel is from the class centre. Preliminary observations through variation coefficent validate the efficiency of the technique to detect outliers. Then, various subsamples are defined by applying different thresholds to exclude outlier pixels from the classification process. The classification results prove the robustness of the Maximum Likelihood and Spectral Angle Mapper classifiers. Indeed, those classifiers were insensitive to outlier exclusion. On the contrary, the decision tree classifier showed better results when deleting 7.5% of pixels in the training data. The technique managed to detect outliers for all classes. In this study, few outliers were present in the training data, so that the classification quality was not deeply affected by the outliers

    Optical microsphere resonators: optimal coupling to high-Q whispering gallery modes

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    A general model is presented for coupling of high-QQ whispering-gallery modes in optical microsphere resonators with coupler devices possessing discrete and continuous spectrum of propagating modes. By contrast to conventional high-Q optical cavities, in microspheres independence of high intrinsic quality-factor and controllable parameters of coupling via evanescent field offer variety of regimes earlier available in RF devices. The theory is applied to the earlier-reported data on different types of couplers to microsphere resonators and complemented by experimental demonstration of enhanced coupling efficiency (about 80%) and variable loading regimes with Q>10^8 fused silica microspheres.Comment: 14 pages, 4 figure

    Особенности развития гаптофитовых и динофитовых водорослей в олигоценовых бассейнах Северного Перитетиса

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    На основании изучения наннопланктона и диноцист проведены палеоэкологические реконструкции разных типов олигоценовых бассейнов Северного Перитетиса. Установлены ассоциации фитопланктона морских глубоководных, мелководных, относительно холодно- и тепловодных, а также лагунных палеобассейнов. Гаптофитовые (наннопланктон) присутствуют только в карбонатных прослоях пород, наиболее благоприятные условия для их развития были в Карпатском бассейне кросненского типа, в бассейнах самого раннего рюпеля Германии и юга Украины. Диноцисты представлены во всех типах олигоценовых бассейнов. Установлены корреляционные уровни по нанно- и динопланктону, позволяющие обосновать нижнюю и верхнюю границы олигоцена и уровень опреснения в середине рюпеля.Вивчення нанопланктону та диноцист з різних типів олігоценових басейнів Північного Перитетіса дозволило провести палеоекологічні реконструкції. Встановлені асоціації фітопланктону морських глибоководних, прибережно-мілководних відносно холодно- и тепловодних, лагунних, напівізольованих з ендеміками. Нанопланктон виявлено лише в карбонатних прошарках, найбільш сприятливі умови для його розвитку були у Карпатському басейні кросненського типу, у самому ранньому рюпелі Німеччини та півдня України. Диноцисти виявлені у всіх типах олігоценових басейнів. Встановлені корелятивні рівні за нано- та динопланктоном, які дозволяють обґрунтувати нижню і верхню границі олігоцену та рівень розпріснення в середині рюпелю.A study of nannofossils and dinocysts from different types of Oligocene basins of the Northern Peri-Thetys resulted in paleoecological reconstructions. The following phytoplankton associations were recognized: cold-water; littoral shallow-water relatively cold- and warm-water; lagoon; semi-isolated with endemics. Nannofossils were present in carbonaceous sediments, with more favorable conditions for them being in the Carpathian basin of Krosnensky type, in the earliest Rupelian of Germany and Southern Ukraine. Dinocysts were identified in all types of Oligocene basins. Correlation levels identified by nannofossils and dinocysts allowed us to substantiate the lower and upper Oligocene boundaries and degree of desalination in the Middle Rupelian

    The Drosophila Anion Exchanger (DAE) lacks a detectable interaction with the spectrin cytoskeleton

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    <p>Abstract</p> <p>Background</p> <p>Current models suggest that the spectrin cytoskeleton stabilizes interacting ion transport proteins at the plasma membrane. The human erythrocyte anion exchanger (AE1) was the first membrane transport protein found to be associated with the spectrin cytoskeleton. Here we evaluated a conserved anion exchanger from Drosophila (DAE) as a marker for studies of the downstream effects of spectrin cytoskeleton mutations.</p> <p>Results</p> <p>Sequence comparisons established that DAE belongs to the SLC4A1-3 subfamily of anion exchangers that includes human AE1. Striking sequence conservation was observed in the C-terminal membrane transport domain and parts of the N-terminal cytoplasmic domain, but not in the proposed ankyrin-binding site. Using an antibody raised against DAE and a recombinant transgene expressed in <it>Drosophila </it>S2 cells DAE was shown to be a 136 kd plasma membrane protein. A major site of expression was found in the stomach acid-secreting region of the larval midgut. DAE codistributed with an infolded subcompartment of the basal plasma membrane of interstitial cells. However, spectrin did not codistribute with DAE at this site or in anterior midgut cells that abundantly expressed both spectrin and DAE. Ubiquitous knockdown of DAE with dsRNA eliminated antibody staining and was lethal, indicating that DAE is an essential gene product in <it>Drosophila</it>.</p> <p>Conclusions</p> <p>Based on the lack of colocalization and the lack of sequence conservation at the ankyrin-binding site, it appears that the well-characterized interaction between AE1 and the spectrin cytoskeleton in erythrocytes is not conserved in <it>Drosophila</it>. The results establish a pattern in which most of the known interactions between the spectrin cytoskeleton and the plasma membrane in mammals do not appear to be conserved in <it>Drosophila</it>.</p

    Asymmetric Synthesis of Cyclohexene Nucleoside Analogues

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    The asymmetric synthesis of novel cyclohexene nucleoside analogues 12 and 15 is described. An enantiospecific DielsAlder reaction between (E,E)-diene 2 and (+)-5-(D-mentyloxy)-2(5H)- furanone 3 provided the cycloadduct isomer 4. Three additional steps yielded amine 8 allowing the constructions of the thymine and adenine moieties to afford intermediates 11 and 14, respectively. Amination or cyclization and removal of the protecting groups occurred in one step in the presence of ammonia, giving the target six-membered ring nucleosides
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