1,187 research outputs found
Avaliação e manejo do solo com a tecnologia de corte e trituração visando a sustentabilidade do sistema de produção da agricultura familiar, com ênfase em alternativas ao uso do fogo na Amazônia.
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Quantum Kalb-Ramond Field in D-dimensional de Sitter Spacetimes
In this work we investigate the quantum theory of the Kalb-Ramond fields
propagating in dimensional de Sitter spacetimes using the dynamic invariant
method developed by Lewis and Riesenfeld [J. Math. Phys. 10, 1458 (1969)] to
obtain the solution of the time-dependent Schr\"odinger equation. The wave
function is written in terms of a number quantity satisfying of the
Milne-Pinney equation, whose solution can be expressed in terms of two
independent solutions of the respective equation of motion. We obtain the exact
solution for the quantum Kalb-Ramond field in the de Sitter background and
discuss its relation with the Cremmer-Scherk-Kalb-Ramond model
Caracterização do sistema de produção de ovinos Santa Inês no Estado de Sergipe.
Com o presente trabalho objetivou-se caracterizar a produção ovina da raça Santa Inês no Estado de Sergipe, referência nacional pela qualidade genética. Através de 54 entrevistas semi-estruturadas e visitas às propriedades, obteve-se o perfil dos criadouros com relação ao manejo sanitário, nutricional e reprodutivo, bem como, finalidade e destino da criação. No geral, as propriedades apresentaram rebanhos de tamanho bastante variável, sendo o sistema semi-intensivo o mais utilizado. Em sua maioria, as criações tinham acompanhamento técnico regular e destinavam-se ao abate ou exploração genética. Criações com assistência veterinária associada a práticas adequadas de manejo mostraram maior produtividade. A carne ovina apresenta crescente demanda de mercado, porém a reduzida quantidade de abatedouros e frigoríficos no Estado parece contribuir como fator determinante para a escoação da produção para feiras livres sem fiscalização sanitária
Produção de grãos de milho e atributos químicos de solo influenciados pela aplicação de escória de siderurgia em um latossolo amarelo distrófico.
A maioria dos solos da Amazônia apresenta características de elevada acidez, sendo necessária a aplicação de corretivos para a obtenção de produtividades satisfatórias das culturas..
Macronutrientes em diferentes partes de indivíduos de açaizeiro (Euterpe oleracea mart.) provenientes de populações nativas de municípios do estado do Pará.
O açaizeiro é uma espécies típica de crescente valor comercial nos mercados nacional e internacional, sobretudo de alto valor cultural para a população local, o açaí é um aliemnto nutritivo..
Dynamical Mass Constraints on Low-Mass Pre-Main-Sequence Stellar Evolutionary Tracks: An Eclipsing Binary in Orion with a 1.0 Msun Primary and an 0.7 Msun Secondary
We report the discovery of a double-lined, spectroscopic, eclipsing binary in
the Orion star-forming region. We analyze the system spectroscopically and
photometrically to empirically determine precise, distance-independent masses,
radii, effective temperatures, and luminosities for both components. The
measured masses for the primary and secondary, accurate to ~1%, are 1.01 Msun
and 0.73 Msun, respectively; thus the primary is a definitive pre-main-sequence
solar analog, and the secondary is the lowest-mass star yet discovered among
pre-main-sequence eclipsing binary systems. We use these fundamental
measurements to test the predictions of pre-main-sequence stellar evolutionary
tracks. None of the models we examined correctly predict the masses of the two
components simultaneously, and we implicate differences between the theoretical
and empirical effective temperature scales for this failing. All of the models
predict the observed slope of the mass-radius relationship reasonably well,
though the observations tend to favor models with low convection efficiencies.
Indeed, considering our newly determined mass measurements together with other
dynamical mass measurements of pre-main-sequence stars in the literature, as
well as measurements of Li abundances in these stars, we show that the data
strongly favor evolutionary models with inefficient convection in the stellar
interior, even though such models cannot reproduce the properties of the
present-day Sun.Comment: Accepted by Ap
Monitoring young associations and open clusters with Kepler in two-wheel mode
We outline a proposal to use the Kepler spacecraft in two-wheel mode to
monitor a handful of young associations and open clusters, for a few weeks
each. Judging from the experience of similar projects using ground-based
telescopes and the CoRoT spacecraft, this program would transform our
understanding of early stellar evolution through the study of pulsations,
rotation, activity, the detection and characterisation of eclipsing binaries,
and the possible detection of transiting exoplanets. Importantly, Kepler's wide
field-of-view would enable key spatially extended, nearby regions to be
monitored in their entirety for the first time, and the proposed observations
would exploit unique synergies with the GAIA ESO spectroscopic survey and, in
the longer term, the GAIA mission itself. We also outline possible strategies
for optimising the photometric performance of Kepler in two-wheel mode by
modelling pixel sensitivity variations and other systematics.Comment: 10 pages, 6 figures, white paper submitted in response to NASA call
for community input for alternative science investigations for the Kepler
spacecraf
Dual Spaces of Resonance In Thick Branes
In this work we consider form fields in a brane embedded in a
space-time. The membrane is generated by a domain wall in a
Randall-Sundrum-like scenario. We study conditions for localization of zero
modes of these fields. The expression agrees and generalizes the one found for
the zero, one, two and three-forms in a brane. By a generalization we mean
that our expression is valid for any form in an arbitrary dimension with
codimension one. We also point out that, even without the dilaton coupling,
some form fields are localized in the membrane. The massive modes are
considered and the resonances are calculated using a numerical method. We find
that different spaces have identical resonance structures, which we call dual
spaces of resonances(DSR).Comment: 15 page
Descriptive analysis, overall acceptance and CATA (Check All That Apply) of Iamb meat from different genetic groups.
Lamb meat consumption has been increasing in Brazil and consumers have been expecting a high quality product. In the meat production system, the genotype is an important factor that affects the quantity of muscle and fat distribution throughout the carcass and consequently the meat quality.9-12th April 2018
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