69,486 research outputs found
Mortalidade de lagartas de primeiro instar do curuquerê alimentado com folhas de algodoeiro tratadas com extrato de sisal.
A monopole solution from noncommutative multi-instantons
We extend the relation between instanton and monopole solutions of the
selfduality equations in SU(2) gauge theory to noncommutative space-times.
Using this approach and starting from a noncommutative multi-instanton solution
we construct a U(2) monopole configuration which lives in 3 dimensional
ordinary space. This configuration resembles the Wu-Yang monopole and satisfies
the selfduality (Bogomol'nyi) equations for a U(2) Yang-Mills-Higgs system.Comment: 19 pages; title and abstract changed, brane interpretation corrected.
Version to appear in JHE
The Jacobi identity for Dirac-like brackets
For redundant second-class constraints the Dirac brackets cannot be defined
and new brackets must be introduced. We prove here that the Jacobi identity for
the new brackets must hold on the surface of the second-class constraints. In
order to illustrate our proof we work out explicitly the cases of a fractional
spin particle in 2+1 dimensions and the original Brink-Schwarz massless
superparticle in D=10 dimensions in a Lorentz covariant constraints separation.Comment: 14 pages, Latex. Final version to be published in Int. J. Mod. Phys.
Seletividade e eficácia de herbicidas aplicados em pós-emergência na cultura do sorgo forrageiro.
Oxygen clamps in gold nanowires
We investigate how the insertion of an oxygen atom in an atomically thin gold
nanowire can affect its rupture. We find, using ab initio total energy density
functional theory calculations, that O atoms when inserted in gold nanowires
form not only stable but also very strong bonds, in such a way that they can
extract atoms from a stable tip, serving in this way as a clamp that could be
used to pull a string of gold atoms.Comment: 4 pages; 4 figure
Filtragem do sêmen de garanhão para a seleção de espermatozóides móveis e aumento na taxa de fertilidade.
Foi estudado método em que o semem passa por um tratamento de filtragem que permite separar os espermatozóides móveis, melhorando as taxas de normalidade e fertilidade
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