22,482 research outputs found
Exact solution for the energy density inside a one-dimensional non-static cavity with an arbitrary initial field state
We study the exact solution for the energy density of a real massless scalar
field in a two-dimensional spacetime, inside a non-static cavity with an
arbitrary initial field state, taking into account the Neumann and Dirichlet
boundary conditions. This work generalizes the exact solution proposed by Cole
and Schieve in the context of the Dirichlet boundary condition and vacuum as
the initial state. We investigate diagonal states, examining the vacuum and
thermal field as particular cases. We also study non-diagonal initial field
states, taking as examples the coherent and Schrodinger cat states.Comment: 10 pages, 8 figure
Bioclimatologia aplicada à produção de bovinos leiteiros nos trópicos.
bitstream/item/78361/1/documento-188.pd
Geometric scaling of purely-elastic flow instabilities
We present a combined experimental, numerical and theoretical investigation
of the geometric scaling of the onset of a purely-elastic flow instability in a
serpentine channel. Good qualitative agreement is obtained between experiments,
using dilute solutions of flexible polymers in microfluidic devices, and
two-dimensional numerical simulations using the UCM model. The results are
confirmed by a simple theoretical analysis, based on the dimensionless
criterion proposed by Pakdel-McKinley for onset of a purely-elastic
instability
Diagnóstico sorológico de Brucella ovis em ovinos do Estado da Paraíba.
Resumo: A Brucelose ovina, causada pela Brucella ovis, é responsável por perdas econômicas, principalmente na fertilidade do rebanho. Foi realizado um levantamento sorológico em ovinos procedentes de duas mesorregiões do Estado da Paraíba. Foram examinadas 240 amostras séricas de animais pertencentes a 24 propriedades de oito municípios. As amostras foram testadas pela técnica de imunodifusão em gel de ágar (IDGA). Dos 240 animais investigados, 13 (5,4%) apresentaram resultados positivos para Brucella ovis. Das propriedades analisadas, 45,8% (11/24) possuíam, pelo menos, um animal soropositivo. Os resultados obtidos neste trabalho são indícios de que a infecção por Brucella ovis encontra-se presente nos ovinos das duas mesorregiões do Estado da Paraíba, sendo necessária a adoção de medidas sanitárias para evitar a propagação da doença nos rebanhos. Abstract: Ovine Brucellosis, caused by Brucella ovis, is responsible for economic losses, especially in flock fertility. A serological survey was performed in two mesorregions of Paraíba State. 240 serum samples were examined from 24 sheep flocks belonged to eight different municipalities. Samples were tested by agar gel immunodiffusion technique (AGID). 13 of 240 (5.4%) animals tested were seropositive for Brucella ovis. 45.8% (11/24) of analyzed flocks had, at least, one seropositive animal. Those results suggest that the infection by Brucella ovis is present in ovine of two mesorregions of Paraíba State. So that, it is necessary to adopt sanitary measures to avoid the disease spread in livestock
The extended gaussian ensemble and metastabilities in the Blume-Capel model
The Blume-Capel model with infinite-range interactions presents analytical
solutions in both canonical and microcanonical ensembles and therefore, its
phase diagram is known in both ensembles. This model exhibits nonequivalent
solutions and the microcanonical thermodynamical features present peculiar
behaviors like nonconcave entropy, negative specific heat, and a jump in the
thermodynamical temperature. Examples of nonequivalent ensembles are in general
related to systems with long-range interactions that undergo canonical
first-order phase transitions. Recently, the extended gaussian ensemble (EGE)
solution was obtained for this model. The gaussian ensemble and its extended
version can be considered as a regularization of the microcanonical ensemble.
They are known to play the role of an interpolating ensemble between the
microcanonical and the canonical ones. Here, we explicitly show how the
microcanonical energy equilibrium states related to the metastable and unstable
canonical solutions for the Blume-Capel model are recovered from EGE, which
presents a concave "extended" entropy as a function of energy.Comment: 6 pages, 5 eps figures. Presented at the XI Latin American Workshop
on Nonlinear Phenomena, October 05-09 (2009), B\'uzios (RJ), Brazil. To
appear in JPC
Three-dimensional Continuum Radiative Transfer Images of a Molecular Cloud Core Evolution
We analyze a three-dimensional smoothed particle hydrodynamics simulation of
an evolving and later collapsing pre-stellar core. Using a three-dimensional
continuum radiative transfer program, we generate images at 7 micron, 15
micron, 175 micron, and 1.3 mm for different evolutionary times and viewing
angles. We discuss the observability of the properties of pre-stellar cores for
the different wavelengths. For examples of non-symmetric fragments, it is shown
that, misleadingly, the density profiles derived from a one-dimensional
analysis of the corresponding images are consistent with one-dimensional core
evolution models. We conclude that one-dimensional modeling based on column
density interpretation of images does not produce reliable structural
information and that multidimensional modeling is required.Comment: accepted by ApJL, 4 pages, 4 figure
Large deviations for non-uniformly expanding maps
We obtain large deviation results for non-uniformly expanding maps with
non-flat singularities or criticalities and for partially hyperbolic
non-uniformly expanding attracting sets. That is, given a continuous function
we consider its space average with respect to a physical measure and compare
this with the time averages along orbits of the map, showing that the Lebesgue
measure of the set of points whose time averages stay away from the space
average decays to zero exponentially fast with the number of iterates involved.
As easy by-products we deduce escape rates from subsets of the basins of
physical measures for these types of maps. The rates of decay are naturally
related to the metric entropy and pressure function of the system with respect
to a family of equilibrium states. The corrections added to the published
version of this text appear in bold; see last section for a list of changesComment: 36 pages, 1 figure. After many PhD students and colleagues having
pointed several errors in the statements and proofs, this is a correction to
published article answering those comments. List of main changes in a new
last sectio
Soroprevalência da artrite encefalite caprina em rebanhos das mesorregiões Agreste e Sertão do Estado de Sergipe, Brasil.
Twisted partial actions of Hopf algebras
In this work, the notion of a twisted partial Hopf action is introduced as a
unified approach for twisted partial group actions, partial Hopf actions and
twisted actions of Hopf algebras. The conditions on partial cocycles are
established in order to construct partial crossed products, which are also
related to partially cleft extensions of algebras. Examples are elaborated
using algebraic groups
Manual de catalogação: descrição de recursos eletrônicos na Agência de Informação Embrapa: versão 1.2.
bitstream/CNPTIA/11030/1/doc53.pdfAcesso em 01 dez. 2005
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