37,159 research outputs found
Cartografia tridimensional do solos: aspectos metodológicos e aplicação ao estudo da variabilidade espacial de solos aluviais.
bitstream/CNPS/11852/1/bp242001carttrimsolos.pd
Cavity-aided quantum parameter estimation in a bosonic double-well Josephson junction
We describe an apparatus designed to make non-demolition measurements on a
Bose-Einstein condensate (BEC) trapped in a double-well optical cavity. This
apparatus contains, as well as the bosonic gas and the trap, an optical cavity.
We show how the interaction between the light and the atoms, under appropriate
conditions, can allow for a weakly disturbing yet highly precise measurement of
the population imbalance between the two wells and its variance. We show that
the setting is well suited for the implementation of quantum-limited estimation
strategies for the inference of the key parameters defining the evolution of
the atomic system and based on measurements performed on the cavity field. This
would enable {\it de facto} Hamiltonian diagnosis via a highly controllable
quantum probe.Comment: 8 pages, 5 figures, RevTeX4; Accepted for publication in Phys. Rev.
Delocalization and wave-packet dynamics in one-dimensional diluted Anderson models
We study the nature of one-electron eigen-states in a one-dimensional diluted
Anderson model where every Anderson impurity is diluted by a periodic function
. Using renormalization group and transfer matrix techniques, we provide
accurate estimates of the extended states which appear in this model, whose
number depends on the symmetry of the diluting function . The density of
states (DOS) for this model is also numerically obtained and its main features
are related to the symmetries of the diluting function . Further, we show
that the emergence of extended states promotes a sub-diffusive spread of an
initially localized wave-packet.Comment: 6 pages, 6 figures, to appear in EPJ
Coherent State Path Integrals in the Weyl Representation
We construct a representation of the coherent state path integral using the
Weyl symbol of the Hamiltonian operator. This representation is very different
from the usual path integral forms suggested by Klauder and Skagerstan in
\cite{Klau85}, which involve the normal or the antinormal ordering of the
Hamiltonian. These different representations, although equivalent quantum
mechanically, lead to different semiclassical limits. We show that the
semiclassical limit of the coherent state propagator in Weyl representation is
involves classical trajectories that are independent on the coherent states
width. This propagator is also free from the phase corrections found in
\cite{Bar01} for the two Klauder forms and provides an explicit connection
between the Wigner and the Husimi representations of the evolution operator.Comment: 23 page
Ponto de colheita e qualidade da uva BRS Isis sob armazenamento refrigerado seguido de temperatura ambiente.
Esse trabalho teve o objetivo de avaliar o ponto de colheita e a qualidade das uvas da cultivar BRS Ísis quando armazenadas sob refrigeração seguida de temperatura ambiente
Adaptabilidade e estabilidade de híbridos de milho nos Estados de Sergipe e Alagoas, no biênio 2001/2002.
Vinte e dois híbridos de milho foram submetidos a 10 ambientes dos Estados de Sergipe e Alagoas, no biênio 2001/2002, visando conhecer a adaptabilidade e a estabilidade desses materiais para fins de recomendação. Utilizou-se o delineamento experimental em blocos ao acaso, com três repetições. A análise de variância conjunta mostrou diferenças significativas entre os híbridos e a existência de diferenças genéticas entre os híbridos quanto às respostas às variações ambientais. O rendimento médio registrado foi de 6.426 kg/ha, o que revela ótima aptidão da região para o desenvolvimento de híbridos de milho. A maioria dos híbridos mostrou alta estabilidade de produção nos ambientes considerados (R2 > 80 %). O material ideal preconizado pelo modelo bissegmentado não foi encontrado no conjunto avaliado. Também não foi encontrado qualquer híbrido que atendesse a todos os requisitos necessários para adaptação nas condições desfavoráveis. Os híbridos que evidenciaram adaptabilidade geral têm importância expressiva para a região
Comment on "Theory and computer simulation for the equation of state of additive hard-disk fluid mixtures"
A flaw in the comparison between two different theoretical equations of state
for a binary mixture of additive hard disks and Monte Carlo results, as
recently reported in C. Barrio and J. R. Solana, Phys. Rev. E 63, 011201
(2001), is pointed out. It is found that both proposals, which require the
equation of state of the single component system as input, lead to comparable
accuracy but the one advocated by us [A. Santos, S. B. Yuste, and M. L\'{o}pez
de Haro, Mol. Phys. 96, 1 (1999)] is simpler and complies with the exact limit
in which the small disks are point particles.Comment: 4 pages, including 1 figur
Mapeamento digital de classes e atributos de solos: métodos, paradigmas e novas técnicas.
Panorama geral sobre os métodos de mapeamento de solos e/ou de suas propriedades, assim como sobre as principais técnicas quantitativas usadas.bitstream/CNPS/11588/1/doc55_mapeamentodigital.pd
Comportamento de híbridos de milho nos Tabuleiros Costeiros e Agreste Estados de Sergipe e Alagoas no ano agrícola de 2003.
Modelling and digital soil mapping of the organic carbon stock in the topsoil (0-10 cm) of Rio de Janeiro State, Brazil.
A soil database with 431 soil profiles of Rio de Janeiro State was used in the scope of a research project entitled "Quantifying the magnitude, spatial distribution and organic carbon in soils of Rio de Janeiro State, using quantitative modeling, GIS and database technologies" (Projeto Carbono_RJ, funded by FAPERJ - Carlos Chagas Filho Foundation for Research Support in Rio de Janeiro State). Considering that these soil data were collected to other purpose, there was only a few sparse data to soil bulk density, which is essential to estimate of soil organic carbon (SOC) stock. To face this problem, pedotransfer functions (PTFs) were estimated to be used in the modeling of organic soil carbon of topsoil (0-10 cm), using s.c.o.r.p.a.n model. The following environmental correlates were used as predictor variables: satellite data, lithology and soil maps, DEM (Digital Elevation Model) and its derivatives as source of information for these variables. This dataset, that represents the best organized soil dataset in Brazil, is working as a trial for learning/teaching of Digital Soil Mapping (DSM) using a variety of methods for predicting soil classes and their properties. The "f" of the equation was modeled by means of multilinear analysis and regression-kriging. Seven different models were built and compared through statistical methods. In a general way, all models performed well to predict the SOC stock. Nevertheless, model 6 (M6) was an exceptional model, presenting the smallest AIC e RMSE, due to the use of existing soil information (polygon soil map) as predictor variable, in addition to the variables used in the other models. The result obtained in M6 was used for mapping topsoil carbon stock at spatial resolution of 90 m
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