597 research outputs found

    Using Landsat 8 image time series for crop mapping in a region of Cerrado, Brazil.

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    Abstract: The objective of this research is to classify agricultural land use in a region of the Cerrado (Brazilian Savanna) biome using a time series of Enhanced Vegetation Index (EVI) from Landsat 8 OLI. Phenological metrics extracted from EVI time series, a Random Forest algorithm and data mining techniques are used in the process of classification. The area of study is a region in the Cerrado in a region of the municipality of Casa Branca, São Paulo state, Brazil. The results are encouraging and demonstrate the potential of phenological parameters obtained from time series of OLI vegetation indices for agricultural land use classification

    Análise da variabilidade espectro-temporal intraespecífica do milho.

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    Remote sensing data has been widely used worldwide to estimate crop field?s parameters such as area. For that purpose, we use automatic classification algorithms to identify different land uses and land covers (e.g. agricultural and native vegetation), groups of crops (e.g. annual and perennial crops) or crops species (e.g. maize, sugarcane or soybean). For agricultural applications, the ultimate goal is to be able to use remote sensing technology to map crops in the specie level, and then to monitor them. One essential input data used in the classifications algorithms is the spectral information of the ground targets (e.g. reflectance and vegetation indices). Therefore, it is important to know the spectral behavior of all targets. However, the ability of one classifier to distinguish between plant species is probably dependent on the amount of intraspecific variability. In other words, if a crop specie has high intraspecific spectral variation, it will be difficult to classify this specie among others. Thus, the aim of this work is to analyze the intraspecific spectral temporal variability of maize crop. To accomplish that, spectral data (OLI/Landsat-8) were acquired from first and second harvest maize plots, cultivated over distinct management systems (irrigated and non-irrigated), along two agricultural crop years, (2014/2015 and 2015/2016). We concluded that maize fields harvested in different years, sowed in different seasons, irrigated or not, have a high temporal spectral variation, which cannot be associated with these known characteristics

    Análise da variabilidade espectro-temporal intraespecífica do milho.

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    Esse estudo visa melhor compreender a variabilidade intraespecífica do comportamento espectral da cultura do milho, ao longo do seu desenvolvimento e averiguar o potencial e as dificuldades de se identificar espectralmente essa cultura por meio de dados obtidos por sensoriamento remoto

    Lem benchmark database for tropical agricultural remote sensing application.

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    Abstract: The monitoring of agricultural activities at a regular basis is crucial to assure that the food production meets the world population demands, which is increasing yearly. Such information can be derived from remote sensing data. In spite of topic?s relevance, not enough efforts have been invested to exploit modern pattern recognition and machine learning methods for agricultural land-cover mapping from multi-temporal, multi-sensor earth observation data. Furthermore, only a small proportion of the works published on this topic relates to tropical/subtropical regions, where crop dynamics is more complicated and difficult to model than in temperate regions. A major hindrance has been the lack of accurate public databases for the comparison of different classification methods. In this context, the aim of the present paper is to share a multi-temporal and multi-sensor benchmark database that can be used by the remote sensing community for agricultural land-cover mapping. Information about crops in situ was collected in Luís Eduardo Magalhães (LEM) municipality, which is an important Brazilian agricultural area, to create field reference data including information about first and second crop harvests. Moreover, a series of remote sensing images was acquired and pre-processed, from both active and passive orbital sensors (Sentinel-1, Sentinel-2/MSI, Landsat-8/OLI), correspondent to the LEM area, along the development of the main annual crops. In this paper, we describe the LEM database (crop field boundaries, land use reference data and pre-processed images) and present the results of an experiment conducted using the Sentinel-1 and Sentinel-2 data

    Monitoramento e controle da pinta preta do mamoeiro.

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    O mamoeiro pode ser afetado por diversas doenças, sendo esse o fator econômico mais importante na produção e exportação de frutos in natura (Nishijima et al. 1994). Dentre as doenças de origem fúngica destaca-se a varíola ou pinta preta, causada por Asperisporium caricae (Speg) Maubl., considerada a doença mais comum do mamoeiro. O patógeno pode infectar tanto as folhas como os frutos. Nas folhas, geralmente nas mais velhas, aparecem na face superior, pequenas lesões mais ou menos circulares, de coloração pardo-claro com um halo amarelo.bitstream/item/110984/1/Comunicado-125-Monitoramento-e-controle-da-pinta-preta-do-mamoeiro.pd

    Busca de relações quando o número de variáveis é muito maior que o de observações: o caso de dados hiperespectrais.

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    Resumo: Experimentos em que são coletadas muitas medidas em cada unidade experimental têm matrizes de dados nas quais o número de colunas (variáveis) é muito maior que o de linhas (observações). Dados hiperespectrais são habitualmente coletados por instrumentos que medem instantaneamente as reflectâncias de um alvo em milhares de comprimentos de onda e podemos considerar que cada uma delas constitui uma variável prognóstica num modelo de regressão. A facilidade na obtenção de cada vez maior número de variáveis simultâneas não se repete na obtenção das observações dessas variáveis. A análise de componentes principais (ACP) é indicada para tratar tal quantidade de variáveis e reduzir a dimensionalidade dos dados, mas sua aplicação ainda exige a obtenção de um grande número de medidas. Já a análise discriminante é usada na tentativa de classificar diferentes alvos, mas precisa ser precedida da seleção de um pequeno subconjunto de bandas, geralmente escolhidas com base em informações preexistentes e não nos próprios dados. A regressão linear permite empregar o método stepwise para selecionar um subconjunto de bandas, mas só é indicada para variáveis dependentes quantitativas. O presente trabalho propõe o uso da regressão logística politômica stepwise para selecionar um pequeno conjunto de bandas espectrais que discrimine alvos em k classes, quando a variável resposta de interesse é nominal. Apresentamos um exemplo no qual os dados espectrais são utilizados para construção de modelos logísticos com um pequeno número de preditores (bandas) para classificação de folhas verdes em classes correspondentes a três culturas agrícolas: soja perene, milho e braquiária

    Gastroenteropancreatic Neuroendocrine Neoplasia Characterization in Portugal: Results from the NETs Study Group of the Portuguese Society of Endocrinology, Diabetes and Metabolism

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    Background: The incidence of gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) has been increasing in the last five decades, but there is no large-scale data regarding these tumours in Portugal. We conducted a cross-sectional, multicentric study in main Portuguese centers to evaluate the clinical, pathological, and therapeutic profile of GEP-NENs. Methods: From November, 2012, to July, 2014, data from 293 patients diagnosed with GEP-NENs from 15 centers in Portugal was collected and registered in an online electronic platform. Results: Median age at diagnosis was 56.5 (range: 15-87) years with a preponderance of females (54.6%). The most frequent primary sites were the pancreas (31.1%), jejunum-ileum (24.2%), stomach (13.7%), and rectum (8.5%). Data regarding hormonal status was not available in most patients (82.3%). Stratified by the tumour grade (WHO 2010 classification), we observed 64.0% of NET G1, 24.7% of NET G2, and 11.3% of NEC. Poorly differentiated tumours occurred mainly in older patients (p = 0.017), were larger (p < 0.001), and presented more vascular (p = 0.004) and lymphatic (p = 0.001) invasion. At the time of diagnosis, 44.4% of GEP-NENs presented metastatic disease. Surgery (79.6%) and somatostatin analogues (30.7%) were the most frequently used therapies of GEP-NENs with reported grading. Conclusion: In general, Portuguese patients with GEP-NENs presented similar characteristics to other populations described in the literature. This cross-sectional study represents the first step to establish a national database of GEP-NENs that may aid in understanding the clinical and epidemiological features of these tumours in Portugal. Methods: From November, 2012, to July, 2014, data from 293 patients diagnosed with GEP-NENs from 15 centers in Portugal was collected and registered in an online electronic platform. Results: Median age at diagnosis was 56.5 (range: 15-87) years with a preponderance of females (54.6%). The most frequent primary sites were the pancreas (31.1%), jejunum-ileum (24.2%), stomach (13.7%), and rectum (8.5%). Data regarding hormonal status was not available in most patients (82.3%). Stratified by the tumour grade (WHO 2010 classification), we observed 64.0% of NET G1, 24.7% of NET G2, and 11.3% of NEC. Poorly differentiated tumours occurred mainly in older patients (p = 0.017), were larger (p < 0.001), and presented more vascular (p = 0.004) and lymphatic (p = 0.001) invasion. At the time of diagnosis, 44.4% of GEP-NENs presented metastatic disease. Surgery (79.6%) and somatostatin analogues (30.7%) were the most frequently used therapies of GEP-NENs with reported grading. Conclusion: In general, Portuguese patients with GEP-NENs presented similar characteristics to other populations described in the literature. This cross-sectional study represents the first step to establish a national database of GEP-NENs that may aid in understanding the clinical and epidemiological features of these tumours in Portugal.This study was industry-sponsored by the pharmaceutical company Ipsen Portugal. João Vinagre (CEECIND/00201/2017) and Paula Soares receive funding from the Operational Program for Competitiveness and Internationalization (POCI), Portugal 2020; Portuguese funds through FCT (Fundação para a Ciência e a Tecnologia)/Ministério da Ciência, Tecnologia e Inovação in the framework of the project “Institute for Research and Innovation in Health Sciences” (POCI-01-0145-FEDER-007274) and the project “Advancing Cancer Research: From Basic Knowledge to Application” (NORTE-01-0145-FEDER-000029); and “Projetos Estruturados de I&D&I,” funded by Norte 2020—Programa Operacional Regional do Norte. Further funding was from the European Regional Development Fund (ERDF) through the Operational Program for Competitiveness and Internationalization (COMPETE 2020) and Portuguese national funds via FCT (Fundação para a Ciência e a Tecnologia), under the project “POCI-01-0145-FEDER-016390: CANCEL STEM.” Maria João Bugalho and João Vinagre were funded by the Sociedade Portuguesa de Endocrinologia, Diabetes e Metabolismo through the Study Group for Neuroendocrine Tumours.info:eu-repo/semantics/publishedVersio

    "Nonbaryonic" Dark Matter as Baryonic Color Superconductor

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    We discuss a novel cold dark matter candidate which is formed from the ordinary quarks during the QCD phase transition when the axion domain wall undergoes an unchecked collapse due to the tension in the wall. If a large number of quarks is trapped inside the bulk of a closed axion domain wall, the collapse stops due to the internal Fermi pressure. In this case the system in the bulk, may reach the critical density when it undergoes a phase transition to a color superconducting phase with the ground state being the quark condensate, similar to the Cooper pairs in BCS theory. If this happens, the new state of matter representing the diquark condensate with a large baryon number B1032B \sim 10^{32} becomes a stable soliton-like configuration. Consequently, it may serve as a novel cold dark matter candidate.Comment: Title changed. Two figures and Appendix added. Part on baryogenesis is removed and posted as a separate paper hep-ph/030908
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