3,656 research outputs found
On the Integrability and Chaos of an N=2 Maxwell-Chern-Simons-Higgs Mechanical Model
We apply different integrability analysis procedures to a reduced (spatially
homogeneous) mechanical system derived from an off-shell non-minimally coupled
N=2 Maxwell-Chern-Simons-Higgs model that presents BPS topological vortex
excitations, numerically obtained with an ansatz adopted in a special -
critical coupling - parametric regime. As a counterpart of the regularity
associated to the static soliton-like solution, we investigate the possibility
of chaotic dynamics in the evolution of the spatially homogeneous reduced
system, descendant from the full N=2 model under consideration. The originally
rich content of symmetries and interactions, N=2 susy and non-minimal coupling,
singles out the proposed model as an interesting framework for the
investigation of the role played by (super-)symmetries and parametric domains
in the triggering/control of chaotic behavior in gauge systems.
After writing down effective Lagrangian and Hamiltonian functions, and
establishing the corresponding canonical Hamilton equations, we apply global
integrability Noether point symmetries and Painleveproperty criteria to both
the general and the critical coupling regimes. As a non-integrable character is
detected by the pair of analytical criteria applied, we perform suitable
numerical simulations, as we seek for chaotic patterns in the system evolution.
Finally, we present some Comments on the results and perspectives for further
investigations and forthcoming communications.Comment: 18 pages, 5 figure
Agricultura de montanha: uma prioridade latente na agenda da pesquisa brasileira.
Introdução; Breve histórico do reconhecimento da importância das montanhas; Definição de montanha; Especialidades dos ambientes de montanha; Desenvolvimento sustentável em ambientes de montanha; Agricultura de montanha; Considerações finais
Pagamento por serviços ambientais em ambientes de montanha
Publicado no Cadernos de Agroecologia, v. 6, n. 2, 2011
Produção integrada de manga: manejo pós-colheita e rastreabilidade.
Critérios para colheita; Rastreabilidade.bitstream/CPATSA-2009-09/40395/1/CTE89.pd
Holonomy Transformation in the FRW Metric
In this work we investigate loop variables in Friedman-Robertson-Walker
spacetime. We analyze the parallel transport of vectors and spinors in several
paths in this spacetime in order to classify its global properties. The band
holonomy invariance is analysed in this background.Comment: 8 page
Avaliação por Cromatografia Líquida de Alta Eficiência (Hplc) da Interação Atrazina-Carboximetilcelulose.
bitstream/CNPDIA/10488/1/CT38_2000.pd
Restoring observed classical behavior of the carbon nanotube field emission enhancement factor from the electronic structure
Experimental Fowler-Nordheim plots taken from orthodoxly behaving carbon
nanotube (CNT) field electron emitters are known to be linear. This shows that,
for such emitters, there exists a characteristic field enhancement factor (FEF)
that is constant for a range of applied voltages and applied macroscopic fields
. A constant FEF of this kind can be evaluated for classical CNT
emitter models by finite-element and other methods, but (apparently contrary to
experiment) several past quantum-mechanical (QM) CNT calculations find
FEF-values that vary with . A common feature of most such
calculations is that they focus only on deriving the CNT real-charge
distributions. Here we report on calculations that use density functional
theory (DFT) to derive real-charge distributions, and then use these to
generate the related induced-charge distributions and related fields and FEFs.
We have analysed three carbon nanostructures involving CNT-like nanoprotrusions
of various lengths, and have also simulated geometrically equivalent classical
emitter models, using finite-element methods. We find that when the
DFT-generated local induced FEFs (LIFEFs) are used, the resulting values are
effectively independent of macroscopic field, and behave in the same
qualitative manner as the classical FEF-values. Further, there is fair to good
quantitative agreement between a characteristic FEF determined classically and
the equivalent characteristic LIFEF generated via DFT approaches. Although many
issues of detail remain to be explored, this appears to be a significant step
forwards in linking classical and QM theories of CNT electrostatics. It also
shows clearly that, for ideal CNTs, the known experimental constancy of the FEF
value for a range of macroscopic fields can also be found in appropriately
developed QM theory.Comment: A slightly revised version has been published - citation below -
under a title different from that originally used. The new title is:
"Restoring observed classical behavior of the carbon nanotube field emission
enhancement factor from the electronic structure
- …