Curvas de secagem de sementes de milho utilizando o método intermitente

The objective of this work was the determination of the drying curve of corn seeds for different air temperatures during the intermittent drying process. Three lots of double hybrid AG-162 corn seeds and a D'Andrea dryer, model D-200, were utilized. Air temperatures of 70, 80 and 90°C, were used during the drying process. The following determinations were made: seed moisture content, air temperature at drying, seed temperature in drying roon and drier outled, air relative humidity and environment temperature. Considering the temperature of the drying processes at 70, 80 and 90°C and the reduction of moisture content from 16,5% to 13,0%, the following conclusions were obtained: a) corn seed drying curves in the intermittent drying process can be represented by linear functions; b) the increase of the drying speed and the reduction of total time of seed exposition to hot air can be achieved by temperature elevation of drying air.O presente trabalho teve por objetivo determinar as curvas de secagem de sementes de milho, para diferentes temperaturas do ar, durante a secagem intermitente. Foram utilizados três lotes de sementes de milho do hibrido duplo AG-162 e um secador marca D'Andréa, modelo D-200. As temperaturas do ar de secagem empregadas foram de 70, 80 e 90°C. As seguintes determinações foram realizadas: teor de água das sementes, temperatura do ar de secagem, temperaturas da massa de sementes na câmara de secagem e na saída do secador, umidade relativa do ar e temperatura do ar ambiente. Considerando temperaturas do ar de secagem de 70, 80 e 90°C e reduções do teor de água de 16,5% para 13,0%, os resultados permitem as seguintes conclusões: a) as curvas de secagem de sementes de milho, utilizando o método intermitente, podem ser representadas por funções lineares, b) o aumento da velocidade de secagem e a redução do tempo total de exposição das sementes ao ar aquecido podem ser obtidos pela elevação da temperatura do ar de secagem

Magnetotelluric Imaging of the Lithosphere Across the Variscan Orogen (Iberian Autochthonous Domain, NW Iberia)

A new magnetotelluric (MT) survey comprising 17 MT soundings throughout a 30 km long N30°W transect in the Iberian autochthons domain of NW Iberia (Central Iberian Zone) is presented. The 2-D inversion model shows the resistivity structure of the continental crust up to 10 km depth, heretofore unavailable for this region of the Variscan Orogen. The MT model reveals a wavy structure separating a conductive upper layer underlain by a resistive layer, thus picturing the two main tectonic blocks of a large-scale D2 extensional shear zone (i.e., Pinhel shear zone). The upper layer represents a lower grade metamorphic domain that includes graphite-rich rocks. The lower layer consists of high-grade metamorphic rocks that experienced partial melting and are associated with granites (more resistive) emplaced during crustal thinning. The wavy structure is the result of superimposed crustal shortening responsible for the development of large-scale D3 folds (e.g., Marofa synform), later deflected and refolded by a D4 strike-slip shear zone (i.e., Juzbado-Penalva do Castelo shear zone). The later contribution to the final structure of the crust is marked by the intrusion of postkinematic granitic rocks and the propagation of steeply dipping brittle fault zones. Our study demonstrates that MT imaging is a powerful tool to understand complex crustal structures of ancient orogens in order to design future prospecting surveys for mineral deposits of economic interest

Impacts des systèmes de culture en semis direct avec couverture végétale (SCV) sur la dynamique de l'eau, de l'azote minéral et du carbone du sol dans les cerrados brésiliens

Dans les conditions tropicales humides des cerrados brésiliens, de nouveaux systèmes de culture étaient nécessaires pour assurer une production agricole durable. Des systèmes en semis direct avec couverture végétale (SCV) ont été mis au point en incorporant des plantes de couverture avant ou après la culture commerciale. Depuis 1999, différentes études ont été réalisées dans le cadre d'un projet de recherche franco-brésilien. Elles ont permis de quantifier les effets de ces SCV sur les dynamiques de l'eau, de l'azote et du carbone en particulier. Il a été ainsi confirmé que les SCV permettent de diminuer le ruissellement et donc l'érosion qui lui est liée. De même, les SCV permettent une fourniture en azote supérieure pour la plante commerciale. L'eau et l'azote non valorisées par cette culture peuvent l'être par la plante de couverture additionnelle, de même que l'eau et l'azote mis à disposition en dehors de ce cycle commercial. Les importantes restitutions de phytomasse de ces nouveaux systèmes à plusieurs plantes dans l'année aboutissent à un bilan de carbone positif et une augmentation des taux de matière organique des sols. (Résumé d'auteur

Contribuição dos Sistemas Agrosilvopastoris na Captação de Carbono

The Kyoto Protocol, entered into force in February 2005, emphasizes in Article 12 that projects with Clean Development Mechanism must be chosen to meet both the global concern of climatic changes and the national interests of sustainable development. After more than ten years, however, these goals still need to be adjusted to practice. In view of this necessity, this review seeks to elucidate some aspects related to the use of agroforestry systems associated with carbon sequestration, aiming to extend to farmers the perspectives of sustainable development associated with a new possibility of income source.O Protocolo de Kyoto, que entrou em vigor em fevereiro de 2005, enfatiza em seu 12º artigo que projetos sob o Mecanismo de Desenvolvimento Limpo devem ser selecionados para atender tanto à preocupação internacional com as mudanças climáticas quanto aos interesses nacionais de desenvolvimento sustentável. Passados mais de 10 anos,  entretanto, estes objetivos ainda precisam ser adequados à prática. Tendo em vista essa necessidade a presente revisão busca elucidar alguns aspectos relacionados à utilização de sistemas agrossilvopastoris associados ao seqüestro de carbono, de modo a ampliar ao produtor rural as perspectivas de desenvolvimento sustentável aliadas a uma nova possibilidade de fonte de renda

Quantifying the interdisciplinarity of scientific journals and fields

There is an overall perception of increased interdisciplinarity in science, but this is difficult to confirm quantitatively owing to the lack of adequate methods to evaluate subjective phenomena. This is no different from the difficulties in establishing quantitative relationships in human and social sciences. In this paper we quantified the interdisciplinarity of scientific journals and science fields by using an entropy measurement based on the diversity of the subject categories of journals citing a specific journal. The methodology consisted in building citation networks using the Journal Citation Reports database, in which the nodes were journals and edges were established based on citations among journals. The overall network for the 11-year period (1999-2009) studied was small-world and scale free with regard to the in-strength. Upon visualizing the network topology an overall structure of the various science fields could be inferred, especially their interconnections. We confirmed quantitatively that science fields are becoming increasingly interdisciplinary, with the degree of interdisplinarity (i.e. entropy) correlating strongly with the in-strength of journals and with the impact factor.Comment: 23 pages, 6 figure