2,834 research outputs found
Níveis críticos de fósforo para o estabelecimento de gramíneas forrageiras em Latossolo vermelho amarelo, Álico: II. Experimento de campo.
O objetivo do trabalho foi determinar os níveis criticos de (P) são solo pelos extratores de Mehlich I e Resina e na planta
Níveis criticos de fósforo para o estabelecimento de gramíneas forrageiras em Latossolo vermelho-amarelo, Álico: I: Ensaio em casa de vegetação.
Determinar níveis críticos de P no solo, avaliados pelos extratores de Mehlich I e Resina e na planta, para o estabelecimento das gramineas Brachiaria decumbens Stapf., Brachiaria brizantha Stapf. cv. Marandu e Panicum maximum Jacq., em Latossolo vermelho amarelo, Alico
Disponibilidade de fósforo pelos extratores de Mehlich 1 e resina em latossolo vermelho amarelo, álico cultivado com três gramíneas forrageiras.
Comparação dos extratores de mehlich 1 e resina na avaliação do P disponível em latossolo vermelho amarelo, alico cultivado com gramineas brachiaria decumbens
Comment on: Modular Theory and Geometry
In this note we comment on part of a recent article by B. Schroer and H.-W.
Wiesbrock. Therein they calculate some new modular structure for the
U(1)-current-algebra (Weyl-algebra). We point out that their findings are true
in a more general setting. The split-property allows an extension to
doubly-localized algebras.Comment: 13 pages, corrected versio
Effective quantum gravity observables and locally covariant QFT
Perturbative algebraic quantum field theory (pAQFT) is a mathematically
rigorous framework that allows to construct models of quantum field theories on
a general class of Lorentzian manifolds. Recently this idea has been applied
also to perturbative quantum gravity, treated as an effective theory. The
difficulty was to find the right notion of observables that would in an
appropriate sense be diffeomorphism invariant. In this article I will outline a
general framework that allows to quantize theories with local symmetries (this
includes infinitesimal diffeomorphism transformations) with the use of the BV
(Batalin-Vilkovisky) formalism. This approach has been successfully applied to
effective quantum gravity in a recent paper by R. Brunetti, K. Fredenhagen and
myself. In the same paper we also proved perturbative background independence
of the quantized theory, which is going to be discussed in the present work as
well.Comment: 16 pages, based on a plenary talk given at the 14th Marcel Grossmann
Meeting in Rome (July 2015
A Way Out of the Quantum Trap
We review Event Enhanced Quantum Theory (EEQT). In Section 1 we address the
question "Is Quantum Theory the Last Word". In particular we respond to some of
recent challenging staments of H.P. Stapp. We also discuss a possible future of
the quantum paradigm - see also Section 5. In Section 2 we give a short sketch
of EEQT. Examples are given in Section 3. Section 3.3 discusses a completely
new phenomenon - chaos and fractal-like phenomena caused by a simultaneous
"measurement" of several non-commuting observables (we include picture of
Barnsley's IFS on unit sphere of a Hilbert space). In Section 4 we answer
"Frequently Asked Questions" concerning EEQT.Comment: Replacement. Corrected affiliation. Latex, one .jpg figure. To appear
in Proc. Conf. Relativistic Quantum Measurements, Napoli 1998, Ed. F.
Petruccion
Nonlinear Quantum Mechanics and Locality
It is shown that, in order to avoid unacceptable nonlocal effects, the free
parameters of the general Doebner-Goldin equation have to be chosen such that
this nonlinear Schr\"odinger equation becomes Galilean covariant.Comment: 10 pages, no figures, also available on
http://www.pt.tu-clausthal.de/preprints/asi-tpa/012-97.htm
Vacuum Structures in Hamiltonian Light-Front Dynamics
Hamiltonian light-front dynamics of quantum fields may provide a useful
approach to systematic non-perturbative approximations to quantum field
theories. We investigate inequivalent Hilbert-space representations of the
light-front field algebra in which the stability group of the light-front is
implemented by unitary transformations. The Hilbert space representation of
states is generated by the operator algebra from the vacuum state. There is a
large class of vacuum states besides the Fock vacuum which meet all the
invariance requirements. The light-front Hamiltonian must annihilate the vacuum
and have a positive spectrum. We exhibit relations of the Hamiltonian to the
nontrivial vacuum structure.Comment: 16 pages, report \# ANL-PHY-7524-TH-93, (Latex
Entropy inequalities from reflection positivity
We investigate the question of whether the entropy and the Renyi entropies of
the vacuum state reduced to a region of the space can be represented in terms
of correlators in quantum field theory. In this case, the positivity relations
for the correlators are mapped into inequalities for the entropies. We write
them using a real time version of reflection positivity, which can be
generalized to general quantum systems. Using this generalization we can prove
an infinite sequence of inequalities which are obeyed by the Renyi entropies of
integer index. There is one independent inequality involving any number of
different subsystems. In quantum field theory the inequalities acquire a simple
geometrical form and are consistent with the integer index Renyi entropies
being given by vacuum expectation values of twisting operators in the Euclidean
formulation. Several possible generalizations and specific examples are
analyzed.Comment: Significantly enlarged and corrected version. Counterexamples found
for the most general form of the inequalities. V3: minor change
Nonlinear Schr\"odinger equation for a PT symmetric delta-functions double well
The time-independent nonlinear Schr\"odinger equation is solved for two
attractive delta-function shaped potential wells where an imaginary loss term
is added in one well, and a gain term of the same size but with opposite sign
in the other. We show that for vanishing nonlinearity the model captures all
the features known from studies of PT symmetric optical wave guides, e.g., the
coalescence of modes in an exceptional point at a critical value of the
loss/gain parameter, and the breaking of PT symmetry beyond. With the
nonlinearity present, the equation is a model for a Bose-Einstein condensate
with loss and gain in a double well potential. We find that the nonlinear
Hamiltonian picks as stationary eigenstates exactly such solutions which render
the nonlinear Hamiltonian itself PT symmetric, but observe coalescence and
bifurcation scenarios different from those known from linear PT symmetric
Hamiltonians.Comment: 16 pages, 9 figures, to be published in Journal of Physics
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