7,537 research outputs found
Geometry, stochastic calculus and quantum fields in a non-commutative space-time
The algebras of non-relativistic and of classical mechanics are unstable
algebraic structures. Their deformation towards stable structures leads,
respectively, to relativity and to quantum mechanics. Likewise, the combined
relativistic quantum mechanics algebra is also unstable. Its stabilization
requires the non-commutativity of the space-time coordinates and the existence
of a fundamental length constant. The new relativistic quantum mechanics
algebra has important consequences on the geometry of space-time, on quantum
stochastic calculus and on the construction of quantum fields. Some of these
effects are studied in this paper.Comment: 36 pages Latex, 1 eps figur
Stratification of the orbit space in gauge theories. The role of nongeneric strata
Gauge theory is a theory with constraints and, for that reason, the space of
physical states is not a manifold but a stratified space (orbifold) with
singularities. The classification of strata for smooth (and generalized)
connections is reviewed as well as the formulation of the physical space as the
zero set of a momentum map. Several important features of nongeneric strata are
discussed and new results are presented suggesting an important role for these
strata as concentrators of the measure in ground state functionals and as a
source of multiple structures in low-lying excitations.Comment: 22 pages Latex, 1 figur
Field sexual attraction in the sorghum midge, Contarinia sorghicola (Coquillett, 1899) (Diptera, Cecidomyiidae).
No campo, fêmeas da mosca do sorgo, Contarinia sorghicola (Coquillett, 1899), atraem machos da especie para o acasalamento atraves da emissao de feromonio, o que foi comprovado atraves da utilizacao de armadilhas adesivas contendo femeas virgens ou extratos destas, a nivel de campo. O periodo de maior atratividade ocorreu entre 7:30 e 8:30 horas.Suplemento
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