5,087 research outputs found
Avaliação da dormência em acessos precoces do bag amendoim.
Sementes de amendoim apresentam dormência em diferentes graus, sendo esta caracterÃstica mais pronunciada na subespécie hypogaea e em variedades de ciclo mais longo. A dormência é interessante do ponto de visto agronômico por evitar perdas durante a colheita e por estar relacionada à menor contaminação por aflatoxinas. Trinta e três acessos, com ciclo entre 90 e 100 dias, do Banco Ativo de Germoplasma de Amendoim foram avaliados quanto à dormência das sementes 14 dias após a colheita. Vinte sementes de cada acesso, tratadas com fungicida, foram dispostas em papel germitest umedecido em incubadas a 30 oC em germinador no Laboratório de Qualidade de Sementes da Embrapa Arroz e Feijão
Effects of gluon number fluctuations on photon - photon collisions at high energies
We investigate the effects of gluon number fluctuations on the total
, cross sections and the photon structure
function . Considering a model which relates the
dipole-dipole and dipole-hadron scattering amplitudes, we estimate these
observables by using event-by-event and physical amplitudes. We demonstrate
that both analyses are able to describe the LEP data, but predict different
behaviours for the observables at high energies, with the gluon fluctuations
effects decreasing the cross sections. We conclude that the study of interactions can be useful to constrain the QCD dynamics.Comment: 9 pages, 6 figures. Improved version with two new figures. Version to
be published in Physical Review
Nuclear shadowing from exclusive quarkonium photoproduction at the BNL RHIC and CERN LHC
The photonuclear production of vector mesons in ultraperipheral heavy ion
collisions is investigated within the collinear approach using different
parameterizations for the nuclear gluon distribution. The integrated cross
section and the rapidity distribution for the () process are computed for energies of RHIC and LHC. A comparison with
the recent PHENIX data on coherent production of mesons is also
presented. We demonstrate that the study of the exclusive quarkonium
photoproduction can be used to constrain the nuclear effects in the gluon
distribution.Comment: 8 pages, 4 figures, 2 tables. Version to be published in Physical
Review
Twisted Conjugacy Classes in Lattices in Semisimple Lie Groups
Given a group automorphism , one has an action of
on itself by -twisted conjugacy, namely, .
The orbits of this action are called -conjugacy classes. One says that
has the -property if there are infinitely many
-conjugacy classes for every automorphism of . In this
paper we show that any irreducible lattice in a connected semi simple Lie group
having finite centre and rank at least 2 has the -property.Comment: 6 page
Occupation time of exclusion processes with conductances
Em publicação em "Journal of statistical physics". ISSN 0022-4715.We obtain the fluctuations for the occupation time of one-dimensional symmetric exclusion processes with speed change, where the transition rates ({\em conductances}) are driven by a general function . The approach does not require sharp bounds on the spectral gap of the system nor the jump rates to be bounded from above or below. We present some examples and for one of them, we observe that the fluctuations of the current are trivial, but the fluctuations of the occupation time are given by a fractional Brownian Motion. This shows that, in general, the fluctuations of the current and of the occupation time are not of same order.CAPESFundação para a Ciência e a Tecnologia (FCT)CNP
Phase diagram of a random-anisotropy mixed-spin Ising model
We investigate the phase diagram of a mixed spin-1/2--spin-1 Ising system in
the presence of quenched disordered anisotropy. We carry out a mean-field and a
standard self-consistent Bethe--Peierls calculation. Depending on the amount of
disorder, there appear novel transition lines and multicritical points. Also,
we report some connections with a percolation problem and an exact result in
one dimension.Comment: 8 pages, 4 figures, accepted for publication in Physical Review
Search of molecular markers linked to apomixis in species of the genus Paspalum (Plicatula Group).
Crossover to the KPZ equation
We characterize the crossover regime to the KPZ equation for a class of
one-dimensional weakly asymmetric exclusion processes. The crossover depends on
the strength asymmetry () and it occurs at
. We show that the density field is a solution of an
Ornstein-Uhlenbeck equation if , while for it is
an energy solution of the KPZ equation. The corresponding crossover for the
current of particles is readily obtained.Comment: Published by Annales Henri Poincare Volume 13, Number 4 (2012),
813-82
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