4,547 research outputs found

    A new analysis of the GJ581 extrasolar planetary system

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    We have done a new analysis of the available observations for the GJ581 exoplanetary system. Today this system is controversial due to choices that can be done in the orbital determination. The main ones are the ocurrence of aliases and the additional bodies - the planets f and g - announced in Vogt et al. 2010. Any dynamical study of exoplanets requires the good knowledge of the orbital elements and the investigations involving the planet g are particularly interesting, since this body would lie in the Habitable Zone (HZ) of the star GJ581. This region,for this system, is very attractive of the dynamical point of view due to several resonances of two and three bodies present there. In this work, we investigate the conditions under which the planet g may exist. We stress the fact that the planet g is intimately related with the orbital elements of the planet d; more precisely, we conclude that it is not possible to disconnect its existence from the determination of the eccentricity of the planet d. Concerning the planet f, we have found one solution with period 450\approx 450 days, but we are judicious about any affirmation concernig this body because its signal is in the threshold of detection and the high period is in a spectral region where the ocorruence of aliases is very common. Besides, we outline some dynamical features of the habitable zone with the dynamical map and point out the role played by some resonances laying there.Comment: 12 pages, 9 figure

    Design and construction of a low-cost remotely piloted aircraft for precision agriculture applications

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    ArticleThis study aimed to construct a low cost RPA capable of recording georeferenced images. For the construction of the prototype of a quadcopter type RPA, only essential materials were used to allow stable flight. A maximum total weight of 2 kg was stipulated, including frame weight, electronic components, motors and cameras. The aircraft was programmed using a low-cost microcontroller widely used in prototyping and automation research. An electronic circuit board is designed to facilitate the connection of the microcontroller with the other components of the design. Specific software was used for flight control. The prototype was built successfully, being able to lift stable and controllable flight. However, we still need to acquire equipment and programming components capable of enabling autonomous images and flights. The final cost of the RPA was on average 427.00onaverage50intheBrazilianARPmarket( 427.00 on average 50% lower than the values found in the Brazilian ARP market ( 772.81 to $ 1,288.00

    Espacialização da soja nos biomas Amazônia, Cerrado, Mata Atlântica e Pampa entre os anos de 2007 e 2012.

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    Uma das culturas agrícolas que está em maior ascensão no Brasil nas últimas três décadas é a soja, que ocupa 49% da área plantada de grãos no país. A soja é cultivada principalmente nas regiões Sul e Centro-Oeste. A pesquisa feita objetivou demonstrar a distribuição espacial da produção de soja no Brasil em quatro biomas, Amazônia, Cerrado, Mata Atlântica e Pampa, nos anos de 2007 a 2012. A análise de cluster revelou as similaridades entre os biomas Amazônia e Cerrado quanto à produtividade média anual (kg/ha/ano). Os biomas Amazônia e Pampa apresentaram similaridades quanto à área plantada (ha). Mato Grosso, inserido nos biomas Amazônia e Cerrado, foi o estado que apresentou os maiores valores de produção média total e área média plantada

    Experimental Observation of Quantum Correlations in Modular Variables

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    We experimentally detect entanglement in modular position and momentum variables of photon pairs which have passed through DD-slit apertures. We first employ an entanglement criteria recently proposed in [Phys. Rev. Lett. {\bf 106}, 210501 (2011)], using variances of the modular variables. We then propose an entanglement witness for modular variables based on the Shannon entropy, and test it experimentally. Finally, we derive criteria for Einstein-Podolsky-Rosen-Steering correlations using variances and entropy functions. In both cases, the entropic criteria are more successful at identifying quantum correlations in our data.Comment: 7 pages, 4 figures, comments welcom

    Behavioural and physiological responses of rabbits

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    ArticleThe profitability of a rabbit farming system must consider the thermal environment that the animal will be exposed during the productive period. The goal of this study was to evaluate the physiological responses and behaviours of 26 New Zealand rabbits during seven days of their lives at three times a day. The experiment was carried out in rabbit house in the Federal University of Lavras at Lavras, Brazil. To characterize the thermal environment sensors were used to measure the dry bulb temperature and relative humidity at 48 points inside the rabbit house, at 6:00 a.m., 12:00 a.m. and 6:00 p.m. In addition, the temperature and humidity index (THI) was calculated. The respiratory rate and the superficial temperature of the rabbits' ears were measured. Behaviour evaluations were monitored in punctual record, with duration of two min/cage. Later an ethogram was made with the main behaviours identified. Similar data of behaviour and data of physiological responses were identified by using Ward’s method of cluster analysis. It was observed the period of 6 a.m. showed more comfortable conditions of THI values than the others analysed. Besides, physiological responses presented better values at 6:00 a.m. in comparison to 12:00 and 6:00 p.m. Furthermore, in general, a similar behaviour was observed in the rabbits at 12:00 and 6:00 p.m., while at 6:00 a.m. was different. But rabbits demonstrated to be more comfortable at 6 a.m. maybe because at this time environment conditions were better than the rest of the day. Besides, it can be observed that rabbits were more active in sunrise and sunset than in the rest of the day

    RGB vegetation indices applied to grass monitoring: a qualitative analysis

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    ArticleIn developing countries such as Brazil, research on low-cost remote sensing and computational techniques become essential for the development of precision agriculture (PA), and improving the quality of the agricultural products. Faced with the scenario of increasing production of emerald grass (Zoysia Japônica) in Brazil, and the value added the quality of this agricultural product. The objective of this work was to evaluate the performance of RGB (IV) vegetation indices in the identification of exposed soil and vegetation. The study was developed in an irrigated area of 58 ha cultivated with emerald grass at Bom Sucesso, Minas Gerais, Brazil. The images were obtained by a RGB digital camera coupled to an remotely piloted aircraft. The flight plan was setup to take overlapping images of 70% and the aircraft speed was 10 m s -1 . Six RGB Vegetation index (MGVRI, GLI, RGBVI, MPRI, VEG, ExG) were evaluated in a mosaic resulting from the images of the study area. All of the VIs evaluated were affected by the variability of lighting conditions in the area but MPRI and MGVRI were the ones that presented the best results in a qualitative evaluation regarding the discrimination of vegetation and soil
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