348 research outputs found
The genetic diversity of the American oil palm, Elaeis oleifera (Kunth), Corés revealed by nuclear RFLP markers.
Lagrangian approach to a symplectic formalism for singular systems
We develop a Lagrangian approach for constructing a symplectic structure for
singular systems. It gives a simple and unified framework for understanding the
origin of the pathologies that appear in the Dirac-Bergmann formalism, and
offers a more general approach for a symplectic formalism, even when there is
no Hamiltonian in a canonical sense. We can thus overcome the usual limitations
of the canonical quantization, and perform an algebraically consistent
quantization for a more general set of Lagrangian systems.Comment: 30 page
Obtenção e caracterização físico-química de extrudados expandidos a base de arroz, soja e gergelim.
Cobertura do solo e ocorrência de plantas daninhas em área com diferentes rotações entre soja, milho, pastagem e Sistema Santa-Fé.
Obtenção e avaliação das características funcionais de farinhas extrudadas à base de arroz, soja e gergelim.
Podolsky Electromagnetism at Finite Temperature: Implications on Stefan-Boltzmann Law
In this work we study Podolsky electromagnetism in thermodynamic equilibrium.
We show that a Podolsky mass-dependent modification to the Stefan-Boltzmann law
is induced and we use experimental data to limit the possible values for this
free parameter.Comment: 13 pages, submitted to Physical Review
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
Avaliação de cultivares de milho e épocas de semeadura na safrinha na região de Rio Verde-GO.
On singular Lagrangians affine in velocities
The properties of Lagrangians affine in velocities are analyzed in a
geometric way. These systems are necessarily singular and exhibit, in general,
gauge invariance. The analysis of constraint functions and gauge symmetry leads
us to a complete classification of such Lagrangians.Comment: AMSTeX, 22 page
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