10 research outputs found
Predição De Classes De Solo Por Mineração De Dados Em årea Da Bacia Sedimentar Do São Francisco
The objective of this work was to evaluate different strategies for the prediction of soil class distribution on digital soil maps of areas without reference data, in the sedimentary basin of San Francisco, in the north of the state of Minas Gerais, Brazil. The strategies included: Taxonomic generalization, training by field observations, training set expansion, and the use of different data mining algorithms. Four matrices were developed, differentiated by the volume of data for machine learning and by soil taxonomic levels to be predicted. The performance of the machine learning algorithms-Random Forest, J48, and MLP-, associated with discretization, class balancing, variable selection, and expansion of the training set was evaluated. Class balancing, variable discretization by equal frequencies, and the Random Forest algorithm showed the best performances. The representativeness extension of field observations, that assumes a larger training area, brought no predictive gain. Soil taxonomic generalization to the suborder level reduces the fragmentation of mapped polygons and improves the accuracy of digital soil maps. When generated by training on in situ soil observations at the mapping area, digital soil maps are as accurate as those trained on preexistent maps.5191396140
Mudas de laranjeira 'valĂȘncia' sobre dois porta-enxertos e sob diferentes manejos de adubação
Rendimento do coentro (Coriandrum sativum L) adubado com esterco bovino em diferentes doses e tempos de incorporação no solo
RESUMO O uso de esterco bovino Ă© de suma importĂąncia para os agricultores familiares que produzem coentro na regiĂŁo de MossorĂł-RN, pois esse insumo Ă© amplamente disponĂvel e utilizado pelos agricultores. Objetivando-se avaliar o Rendimento do coentro fertilizado com esterco bovino em diferentes doses e tempos de incorporação ao solo foi conduzido um experimento no perĂodo de setembro a novembro de 2011, na Fazenda Experimental Rafael Fernandes, da Universidade Federal Rural do Semi-Ărido - UFERSA, Brasil. Os tratamentos consistiram da combinação de quatro doses de esterco bovino incorporadas ao solo: 15,0; 30,0; 45,0 e 60,0 t ha-1 em base seca, com quatro tempos de incorporação: 28; 49; 64 e 80 dias antes da semeadura do coentro - DAS, mais um tratamento controle (ausĂȘncia de adubação). O delineamento experimental utilizado foi em blocos completos casualizados com os tratamentos arranjados em esquema fatorial 4 x 4 + 1 com 3 repetiçÔes. A cultivar de coentro utilizado foi a VerdĂŁo e as variĂĄveis determinadas foram altura e nĂșmero de hastes por planta e rendimento de coentro. O coentro respondeu Ă aplicação de esterco bovino, produzindo rendimentos mĂĄximos de 6453 e 6349 kg ha-1 de massa verde, com a dose de 60 t ha-1 e aos quarenta e seis dias de incorporação antes da semeadura, respectivamente
IntercorrĂȘncia entre leucose enzoĂłtica e tuberculose em bovinos abatidos em frigorĂfico
Interação silĂcio e alumĂnio em plantas de arroz de terras altas cultivadas em solo alumĂnico
Solos com altos teores de Al tĂłxico podem causar diversos danos Ă s plantas e, como consequĂȘncia, diminuir sua produtividade; assim, seu manejo torna-se imprescindĂvel para obter maiores produtividades, e o Si pode ser alternativa para diminuir a toxidez por Al em plantas. O objetivo deste trabalho foi avaliar a interação entre Si e Al em plantas de arroz de terras altas cultivadas em solo naturalmente alumĂnico de textura mĂ©dia arenosa. O delineamento experimental utilizado foi o de blocos inteiramente casualizados, dispostos em esquema fatorial 2 x 5 com quatro repetiçÔes. Os tratamentos empregados foram dois cultivares de arroz de terras altas: BRS Talento (nĂŁo tolerante ao Al, moderno) e Guarani (tolerante ao Al3+, tradicional), alĂ©m de cinco doses de Si (0, 30, 60, 90 e 120 mg dm-3) adicionadas ao solo. O Si fornecido ao solo contribuiu amenizando a toxidez por Al em ambos os cultivares, porĂ©m sĂł houve acrĂ©scimo em produtividade no cultivar BRS Talento. Houve correlação positiva para produtividade de grĂŁos do cultivar BRS Talento e teor de Si nas folhas; jĂĄ o teor de Al nas folhas correlacionou-se com a produtividade de forma negativa; e tambĂ©m houve correlação negativa entre os teores de Si e Al nas folhas, indicando que hĂĄ interação entre Si e Al em plantas de arroz
RelaçÔes solo-vegetação na estruturação de comunidades de cerrado sensu stricto no sul de Minas Gerais, Brasil
Search for magnetically-induced signatures in the arrival directions of ultra-high-energy cosmic rays measured at the Pierre Auger Observatory
We search for signals of magnetically-induced effects in the arrival directions of ultra-high-energy cosmic rays detected at the Pierre Auger Observatory. We apply two different methods. One is a search for sets of events that show a correlation between their arrival direction and the inverse of their energy, which would be expected if they come from the same point-like source, they have the same electric charge and their deflection is relatively small and coherent. We refer to these sets of events as "multiplets". The second method, called "thrust", is a principal axis analysis aimed to detect the elongated patterns in a region of interest. We study the sensitivity of both methods using a benchmark simulation and we apply them to data in two different searches. The first search is done assuming as source candidates a list of nearby active galactic nuclei and starburst galaxies. The second is an all-sky blind search. We report the results and we find no statistically significant features. We discuss the compatibility of these results with the indications on the mass composition inferred from data of the Pierre Auger Observatory. © 2020 IOP Publishing Ltd and Sissa Medialab
Observation of inclined EeV air showers with the radio detector of the Pierre Auger Observatory
With the Auger Engineering Radio Array (AERA) of the Pierre Auger Observatory, we have observed the radio emission from 561 extensive air showers with zenith angles between 60 and 84. In contrast to air showers with more vertical incidence, these inclined air showers illuminate large ground areas of several km2 with radio signals detectable in the 30 to 80 MHz band. A comparison of the measured radio-signal amplitudes with Monte Carlo simulations of a subset of 50 events for which we reconstruct the energy using the Auger surface detector shows agreement within the uncertainties of the current analysis. As expected for forward-beamed radio emission undergoing no significant absorption or scattering in the atmosphere, the area illuminated by radio signals grows with the zenith angle of the air shower. Inclined air showers with EeV energies are thus measurable with sparse radio-antenna arrays with grid sizes of a km or more. This is particularly attractive as radio detection provides direct access to the energy in the electromagnetic cascade of an air shower, which in case of inclined air showers is not accessible by arrays of particle detectors on the ground
Multi-messenger Observations of a Binary Neutron Star Merger
International audienceOn 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 . An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over âŒ10 days. Following early non-detections, X-ray and radio emission were discovered at the transientâs position and days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta