3,817 research outputs found
Vacuumless kinks systems from vacuum ones, an example
Some years ago, Cho and Vilenkin, introduced a model which presents
topological solutions, despite not having degenerate vacua as is usually
expected. Here we present a new model with topological defects, connecting
degenerate vacua but which in a certain limit recovers precisely the one
proposed originally by Cho and Vilenkin. In other words, we found a kind of
parent model for the so called vacuumless model. Then the idea is extended to a
model recently introduced by Bazeia et al. Finally, we trace some comments the
case of the Liouville model.Comment: 11 pages, 4 figure
The quantum brachistochrone problem for non-Hermitian Hamiltonians
Recently Bender, Brody, Jones and Meister found that in the quantum brachistochrone problem the passage time needed for the evolution of certain initial states into specified final states can be made arbitrarily small, when the time-evolution operator is taken to be non-Hermitian but PT-symmetric. Here we demonstrate that such phenomena can also be obtained for non-Hermitian Hamiltonians for which PT-symmetry is completely broken, i.e. dissipative systems. We observe that the effect of a tunable passage time can be achieved by projecting between orthogonal eigenstates by means of a time-evolution operator associated with a non-Hermitian Hamiltonian. It is not essential that this Hamiltonian is PT-symmetric
Calagem e gessagem para o tomateiro e o meloeiro irrigados no Semi-Árido nordestino.
Instalou-se um experimento no Submédio São Francisco com o objetivo de avaliar o efeito da calagem e gessagem na produtividade e qualidade do tomate e melão. O delineamento foi em blocos ao acaso, com quatro repetições e sete tratamentos: 1) testemunha; 2) 0,5 vezes a necessidade de calagem (N.C.) na forma de calcário (0,5 x N.C. -Ca); 3) 1 x N.C. - Ca; 4) 2 x N.C. -Ca; 5) 0,5 x N.C., na forma de 2/3 de calcário e 1/3 de gesso (0,5 x N.C. - CaGe); 6) 1 x N.C -CaGe ; 7) 2 x N.C. -CaGe. Não se verificou efeitos significativos sobre a produtividade do tomate e a qualidade do melão. Com aplicação de 2 t/ha de calcário (1 x N.C -Ca) obteve-se uma produtividade de melão de 22,52 t/ha, significativamente superior à da testemunha, 16,77 t/ha, e reduziu-se a podridão apical do tomate em 80,4% em relação à da testemunha.Suplemento 2
Formação de base de dados para identificação do potencial de fixação biológica de nitrogênio em leguminosas nativas da Mata atlântica no Estado do Rio de Janeiro.
Publicado também no VII Congresso brasileiro de Sistemas Agroflorestais, 201
Time evolution of non-Hermitian Hamiltonian systems
We provide time-evolution operators, gauge transformations and a perturbative
treatment for non-Hermitian Hamiltonian systems, which are explicitly
time-dependent. We determine various new equivalence pairs for Hermitian and
non-Hermitian Hamiltonians, which are therefore pseudo-Hermitian and in
addition in some cases also invariant under PT-symmetry. In particular, for the
harmonic oscillator perturbed by a cubic non-Hermitian term, we evaluate
explicitly various transition amplitudes, for the situation when these systems
are exposed to a monochromatic linearly polarized electric field.Comment: 25 pages Latex, 1 eps figure, references adde
Non-Hermitian Hamiltonians with real eigenvalues coupled to electric fields: from the time-independent to the time dependent quantum mechanical formulation
We provide a reviewlike introduction into the quantum mechanical formalism
related to non-Hermitian Hamiltonian systems with real eigenvalues. Starting
with the time-independent framework we explain how to determine an appropriate
domain of a non-Hermitian Hamiltonian and pay particular attention to the role
played by PT-symmetry and pseudo-Hermiticity. We discuss the time-evolution of
such systems having in particular the question in mind of how to couple
consistently an electric field to pseudo-Hermitian Hamiltonians. We illustrate
the general formalism with three explicit examples: i) the generalized Swanson
Hamiltonians, which constitute non-Hermitian extensions of anharmonic
oscillators, ii) the spiked harmonic oscillator, which exhibits explicit
supersymmetry and iii) the -x^4-potential, which serves as a toy model for the
quantum field theoretical phi^4-theory.Comment: 14 pages, 3 figures, to appear in Laser Physics, minor typos
correcte
Estudo da mesofauna e macrofauna do solo como parâmetro de crescimento em plantios de Araucaria angustifolia.
EVINCI. Resumo 030
Efeito do feijoeiro Olathe Pinto M1-4 geneticamente modificado sobre o desenvolvimento do caruncho Zabrotes subfasciatus.
Foi avaliado o efeito do feijoeiro (Phaseolus vulgaris) Cv. Olathe Pinto M1-4 geneticamente modificado (FGM) sobre o desenvolvimento do Zabrotes subfasciatus durante 10 gerações e comparado com outros cultivares de acordo com os tratamentos: 1) FGM; 2) Cultivar Olathe Pinto convencional (FC); 3) Cultivar Jalo Precoce (padrão de comparação, grão utilizado na criação massal desse inseto); 4) Cultivar Pérola (padrão de comparação como cultivar suscetível); 5) Linhagem de feijoeiro silvestre contendo o alelo arcelina 1, proteína que confere resistência ao caruncho.Resumo ID: 2040-1
Variation of the speed of light with temperature of the expanding universe
From an extended relativistic dynamics for a particle moving in a cosmic
background field with temperature T, we aim to obtain the speed of light with
an explicit dependence on the background temperature of the universe. Although
finding the speed of light in the early universe much larger than its current
value, our approach does not violate the postulate of special relativity.
Moreover, it is shown that the high value of the speed of light in the early
universe was drastically decreased before the beginning of the inflationary
period. So we are led to conclude that the theory of varying speed of light
should be questioned as a possible solution of the horizon problem.Comment: 3 pages and 1 figure; Phys. Rev. D86, 027703 (2012
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