161 research outputs found
Cobertura do solo e ocorrência de plantas daninhas em área com diferentes rotações entre soja, milho, pastagem e Sistema Santa-Fé.
Avaliação de cultivares de milho e épocas de semeadura na safrinha na região de Rio Verde-GO.
Gauge Invariant Factorisation and Canonical Quantisation of Topologically Massive Gauge Theories in Any Dimension
Abelian topologically massive gauge theories (TMGT) provide a topological
mechanism to generate mass for a bosonic p-tensor field in any spacetime
dimension. These theories include the 2+1 dimensional Maxwell-Chern-Simons and
3+1 dimensional Cremmer-Scherk actions as particular cases. Within the
Hamiltonian formulation, the embedded topological field theory (TFT) sector
related to the topological mass term is not manifest in the original phase
space. However through an appropriate canonical transformation, a gauge
invariant factorisation of phase space into two orthogonal sectors is feasible.
The first of these sectors includes canonically conjugate gauge invariant
variables with free massive excitations. The second sector, which decouples
from the total Hamiltonian, is equivalent to the phase space description of the
associated non dynamical pure TFT. Within canonical quantisation, a likewise
factorisation of quantum states thus arises for the full spectrum of TMGT in
any dimension. This new factorisation scheme also enables a definition of the
usual projection from TMGT onto topological quantum field theories in a most
natural and transparent way. None of these results rely on any gauge fixing
procedure whatsoever.Comment: 1+25 pages, no figure
Características físico-químicas e perfil de ácidos graxos de azeites obtidos de diferentes variedades de oliveiras introduzidas no Sul de Minas Gerais - Brasil.
Prioridades da pecuária de corte brasileira - 2018/2019.
Uma pesquisa inédita no Brasil, disponibilizada para acesso público entre 2018 e 2019, buscou traçar um cenário sobre as principais prioridades da pecuária de corte brasileira. A enquete recebeu a contribuição de produtores rurais, empresários, consultores, técnicos, pesquisadores, professores, estudantes e demais atores da cadeia produtiva. Além dos dados para compreender o perfil do entrevistado, a pesquisa navegou por diferentes temas que ajudaram a entender esse panorama da atividade. Os principais resultados da pesquisa vão ajudar no direcionamento de políticas públicas, estratégias de pesquisa e de transferência de tecnologia do setor. O objetivo inicial dessa pesquisa foi identificar as principais prioridades da pecuária de corte brasileira na visão de diferentes atores da cadeia.bitstream/item/222206/1/FL-inf-Lampert-e-outros.pd
A new picture on (3+1)D topological mass mechanism
We present a class of mappings between the fields of the Cremmer-Sherk and
pure BF models in 4D. These mappings are established by two distinct
procedures. First a mapping of their actions is produced iteratively resulting
in an expansion of the fields of one model in terms of progressively higher
derivatives of the other model fields. Secondly an exact mapping is introduced
by mapping their quantum correlation functions. The equivalence of both
procedures is shown by resorting to the invariance under field scale
transformations of the topological action. Related equivalences in 5D and 3D
are discussed. A cohomological argument is presented to provide consistency of
the iterative mapping.Comment: 13 page
Utilização parcial de farinha extrudada de gergelim (Sesamum indicum L.) na elaboração de biscoitos para pacientes celíacos.
A realisation of Lorentz algebra in Lorentz violating theory
A Lorentz non-invariant higher derivative effective action in flat spacetime,
characterised by a constant vector, can be made invariant under infinitesimal
Lorentz transformations by restricting the allowed field configurations. These
restricted fields are defined as functions of the background vector in such a
way that background dependance of the dynamics of the physical system is no
longer manifest. We show here that they also provide a field basis for the
realisation of Lorentz algebra and allow the construction of a Poincar\'e
invariant symplectic two form on the covariant phase space of the theory.Comment: text body edited, reference adde
Chiral bosons and improper constraints
We argue that a consistent quantization of the Floreanini-Jackiw model, as a
constrained system, should start by recognizing the improper nature of the
constraints. Then each boundary conditon defines a problem which must be
treated sparately. The model is settled on a compact domain which allows for a
discrete formulation of the dynamics; thus, avoiding the mixing of local with
collective coordinates. For periodic boundary conditions the model turns out to
be a gauge theory whose gauge invariant sector contains only chiral
excitations. For antiperiodoc boundary conditions, the mode is a second-class
theory where the excitations are also chiral. In both cases, the equal-time
algebra of the quantum energy-momentum densities is a Virasoro algebra. The
Poincar\'e symmetry holds for the finite as well as for the infinite domain.Comment: 13 pages, Revtex file, IF.UFRGS Preprin
- …