50,569 research outputs found
Levantamento de reconhecimento de solos e avaliação do potencial de terras para irrigação do município de Simão Dias, Sergipe.
bitstream/CNPS-2010/14930/1/comtec39-2006-simao-dias.pd
Probing ferroelectricity in highly conducting materials through their elastic response: persistence of ferroelectricity in metallic BaTiO3-d
The question whether ferroelectricity (FE) may coexist with a metallic or
highly conducting state, or rather it must be suppressed by the screening from
the free charges, is the focus of a rapidly increasing number of theoretical
studies and is finally receiving positive experimental responses. The issue is
closely related to the thermoelectric and multiferroic (also magnetic)
applications of FE materials, where the electrical conductivity is required or
spurious. In these circumstances, the traditional methods for probing
ferroelectricity are hampered or made totally ineffective by the free charges,
which screen the polar response to an external electric field. This fact may
explain why more than 40 years passed between the first proposals of FE metals
and the present experimental and theoretical activity. The measurement of the
elastic moduli, Young's modulus in the present case, versus temperature is an
effective method for studying the influence of doping on a FE transition
because the elastic properties are unaffected by electrical conductivity. In
this manner, it is shown that the FE transitions of BaTiO3-d are not suppressed
by electron doping through O vacancies; only the onset temperatures are
depressed, but the magnitudes of the softenings, and hence of the piezoelectric
activity, are initially even increased
Diagnóstico agroambiental do Município de Jatobá, Estado de Pernambuco.
bitstream/CNPS/11863/1/circtec20_2003_jatoba.pd
Levantamento detalhado de solos em uma área de reassentamento de colonos na Bacia do Jatobá - PE.
bitstream/CNPS-2010/14929/1/comtec41-2006-levant-jatoba.pd
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Climatology of easterly wave disturbances over the tropical South Atlantic
A 21-yr climatology of Easterly Waves Disturbances (EWDs) over the Tropical South Atlantic (TSA) has been examined using data from the European Centers for Medium-Range Weather Forecasting (ECMWF) interim reanalysis (ERAI) and satellite data. This includes the frequency distribution of EWDs and their interannual variability. The large-scale environment associated with EWDs has been investigated for the coastal region of Northeast Brazil (NEB) for the rainy (April-August) season using a composite analysis. To better understand the life cycle of EWDs, an automated tracking scheme has been used to track vorticity centers associated with the EWDs in the ERAI data. EWDs were first identified in ERAI, resulting in 518 observed cases. These were found to show notable interannual variability with around 16-40 episodes by year and with average lifetime of 4-6 days. Of the identified EWDs, 97% reached the coast of NEB, of which 64% were convective in nature and 14% moved across the NEB region and reached the Amazon. The annual occurrence of EWDs seems to be lower (higher) during El Niño (La Niña). The monthly occurrence of EWDs shows higher activity in the rainy season. EWDs originate in association with five types of system: cold fronts, convective clusters from the west coast of Africa, Intertropical Convergence Zone and Tropical Upper Tropospheric Cyclonic Vortices. The composite analysis presents strong relative vorticity (RV) and divergence anomalies at low levels, as well as in the vertical profiles of relative humidity and vertical velocity (omega). The precipitation composites show that the EWDs propagate between the TSA and NEB and contribute at least 60% of the total rainfall over the east coast of NEB throughout the rainy season
Análise de Repetibilidade em Caracteres de Arquitetura da Planta e Produção em Pinhão-manso.
O objetivo deste trabalho foi estimar os coeficientes de repetibilidade para produção de grãos, números de ramos, altura e volume de copa do pinhão-manso, nos 10 e 20 anos pós-plantio
Solos do campo experimental da Embrapa Algodão, em Patos-PB: levantamento detalhado e potencial edáfico.
bitstream/CNPS/11833/1/bpd17_2002_patos_pb.pd
Multilinhas como estratégia para reduzir os danos devido ao Colletotrichum lindemuthianum no feijoeiro.
O objetivo do trabalho foi verificar se a mistura de linhagens de feijoeiro de grãos tipo carioca reduz o progresso do fungo C. lindemuthianum, e possíveis danos à produtividade de grãos sob condições de cultivo
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