9,326 research outputs found
Organogênese in vitro de videira.
O objetivo do presente trabalho foi avaliar o efeito da N6-benzilaminopurina (BAP) no processo de regeneração via organogênese in vitro,em sete cultivares de videira
Decoherence of Semiclassical Wigner Functions
The Lindblad equation governs general markovian evolution of the density
operator in an open quantum system. An expression for the rate of change of the
Wigner function as a sum of integrals is one of the forms of the Weyl
representation for this equation. The semiclassical description of the Wigner
function in terms of chords, each with its classically defined amplitude and
phase, is thus inserted in the integrals, which leads to an explicit
differential equation for the Wigner function. All the Lindblad operators are
assumed to be represented by smooth phase space functions corresponding to
classical variables. In the case that these are real, representing hermitian
operators, the semiclassical Lindblad equation can be integrated. There results
a simple extension of the unitary evolution of the semiclassical Wigner
function, which does not affect the phase of each chord contribution, while
dampening its amplitude. This decreases exponentially, as governed by the time
integral of the square difference of the Lindblad functions along the classical
trajectories of both tips of each chord. The decay of the amplitudes is shown
to imply diffusion in energy for initial states that are nearly pure.
Projecting the Wigner function onto an orthogonal position or momentum basis,
the dampening of long chords emerges as the exponential decay of off-diagonal
elements of the density matrix.Comment: 23 pg, 2 fi
Melon prdutivity under different soil coverings and irrigation system in Petrolina - PE
The objective of this work was to evaluate the influence of irrigation system and soil cover on yield of yellow melon in Petrolina / PE. The experiment was carried out in the period from April 09, 2016 to June 8, 2016 and was conducted at the Petrolina campus in the IF Sertão - PE rural area, with a randomized complete block design, 2 x 2 x 3 plot scheme, (One and two lines of drippers per row of plants), and the subsubparcels, three soil cover (black mulching cover), two plots of hybrids (Gladial and 10/00), subplots, two irrigation systems, Cover with mulching grey and without soil cover) and six replicates. Mulching efficiency (MPP) was studied in the soil cover and irrigation system located with drippers for the production of yellow hybrid melon 10/00 and Gladial under field conditions. It was verified the statistical influence of the soil cover on melon productivity
Damage spreading in the mode-coupling equations for glasses
We examine the problem of damage spreading in the off-equilibrium mode
coupling equations. The study is done for the spherical -spin model
introduced by Crisanti, Horner and Sommers. For we show the existence of
a temperature transition well above any relevant thermodynamic transition
temperature. Above the asymptotic damage decays to zero while below
it decays to a finite value independent of the initial damage. This transition
is stable in the presence of asymmetry in the interactions. We discuss the
physical origin of this peculiar phase transition which occurs as a consequence
of the non-linear coupling between the damage and the two-time correlation
functions.Comment: 5 pages, 2 figures, Revtex fil
Effect of the solvent on the conformation of monocrotaline as determined by isotropic and anisotropic NMR parameters.
The conformation in solution of monocrotaline, a pyrrolizidine alkaloid presenting an eleven-membered macrocyclic diester ring, has been investigated using a combination of isotropic and anisotropic NMR parameters measured in four solvents of different polarity (D2 O, DMSO-d6 , CDCl3 , and C6 D6 ). Anisotropic NMR parameters were measured in different alignment media, based on their compatibility with the solvent of interest: cromoglycate liquid crystal solution was used for D2 O, while a PMMA polymer gel was chosen for CDCl3 and C6 D6 , and a poly-HEMA gel for DMSO-d6 . Whereas the pyrrolizidine ring shows an E6 exo-puckered conformation in all of the solvents, the macrocyclic eleven-membered ring adopts different populations of syn-parallel and anti-parallel relative orientation of the carbonyl groups according to the polarity of the solvent
Bose Glass in Large N Commensurate Dirty Boson Model
The large N commensurate dirty boson model, in both the weakly and strongly
commensurate cases, is considered via a perturbative renormalization group
treatment. In the weakly commensurate case, there exists a fixed line under RG
flow, with varying amounts of disorder along the line. Including 1/N
corrections causes the system to flow to strong disorder, indicating that the
model does not have a phase transition perturbatively connected to the Mott
Insulator-Superfluid (MI-SF) transition. I discuss the qualitative effects of
instantons on the low energy density of excitations. In the strongly
commensurate case, a fixed point found previously is considered and results are
obtained for higher moments of the correlation functions. To lowest order,
correlation functions have a log-normal distribution. Finally, I prove two
interesting theorems for large N vector models with disorder, relevant to the
problem of replica symmetry breaking and frustration in such systems.Comment: 16 pages, 7 figure
- …