Numerical modeling of surface runoff and erosion due to moving rainstorms at the drainage basin scale

A physically-based distributed erosion model (MEFIDIS) was applied to evaluate the consequences of storm movement on runoff and erosion from the Alenquer basin in Portugal. Controlled soil flume laboratory experiments were also used to test the model. Nine synthetic circular storms were used, combining three storm diameters (0.5, 1 and 2 times the Alenquer basin's axial length) with three speeds of storm movement (0.5, 1 and 2 m/s); storm intensities were synthesized in order to maintain a constant rainfall depth of 50 mm. The model was applied to storms moving downstream as well as upstream along the basin's axis. In all tests, downstream-moving storms caused significantly higher peak runoff (56.5%) and net erosion (9.1%) than did upstream-moving storms. The consequences for peak runoff were amplified as the storm intensity increased. The hydrograph shapes were also different: for downstream-moving storms, runoff started later and the rising limb was steeper, whereas for upstream moving storms, runoff started early and the rising limb was less steep. Both laboratory and model simulations on the Alenquer basin showed that the direction of storm movement, especially in case of extreme rainfall events, significantly affected runoff and soil loss.http://www.sciencedirect.com/science/article/B6V6C-4K7WTYF-3/1/05f00859098982a6ae43cfee9cc48fe

Avaliação preliminar de genótipos de mandioca em solos sob vegetação de cerrados do Piauí.

Este trabalho tem como objetivos principais: introduzir e selecionar genotipos de mandioca em diferentes mesorregioes, com alto potencial produtivo, associados a elevada percentagem de amido nas raizes para serem recomendados aos produtores de farinha, goma ou tapioca; identificar genotipos com alto potencial de producao de parte aerea, visando sua utilizacao na alimentacao animal.bitstream/item/97589/1/PAND860001.pd

Avaliação preliminar de genótipos de mandioca nos tabuleiros costeiros do Piauí.

bitstream/item/97588/1/PAND850001.pd

Estrutura de uma floresta de terra firme na região de Marabá-PA: a posição do mogno em relação ás outras espécies da comunidade.

bitstream/item/39905/1/Com-Tec-22-Am-Oriental.pd

Cosmological constant constraints from observation-derived energy condition bounds and their application to bimetric massive gravity

Among the various possibilities to probe the theory behind the recent accelerated expansion of the universe, the energy conditions (ECs) are of particular interest, since it is possible to confront and constrain the many models, including different theories of gravity, with observational data. In this context, we use the ECs to probe any alternative theory whose extra term acts as a cosmological constant. For this purpose, we apply a model-independent approach to reconstruct the recent expansion of the universe. Using Type Ia supernova, baryon acoustic oscillations and cosmic-chronometer data, we perform a Markov Chain Monte Carlo analysis to put constraints on the effective cosmological constant $\Omega^0_{\rm eff}$. By imposing that the cosmological constant is the only component that possibly violates the ECs, we derive lower and upper bounds for its value. For instance, we obtain that $0.59 < \Omega^0_{\rm eff} < 0.91$ and $0.40 < \Omega^0_{\rm eff} < 0.93$ within, respectively, $1\sigma$ and $3\sigma$ confidence levels. In addition, about 30\% of the posterior distribution is incompatible with a cosmological constant, showing that this method can potentially rule it out as a mechanism for the accelerated expansion. We also study the consequence of these constraints for two particular formulations of the bimetric massive gravity. Namely, we consider the Visser's theory and the Hassan and Roses's massive gravity by choosing a background metric such that both theories mimic General Relativity with a cosmological constant. Using the $\Omega^0_{\rm eff}$ observational bounds along with the upper bounds on the graviton mass we obtain constraints on the parameter spaces of both theories.Comment: 11 pages, 4 figures, 1 tabl

Principais tuberculos e raizes comercializados na CEASA-PI.

bitstream/item/83419/1/CT920001.pd

Controle químico de plantas daninhas em algodoeiro herbáceo no Cerrado do Estado de Minas Gerais.

bitstream/CNPA/19697/1/COMTEC192.PD

Correlação entre características do solo, composição e estrutura de uma floresta primária de terra firme do Amapá.

bitstream/item/160352/1/comtec7-2001.pd