22,246 research outputs found
-Coloring Parameterized by Pathwidth is {XNLP}-complete
We show that the -Coloring problem is complete for the class XNLP whenparameterized by the pathwidth of the input graph. Besides determining theprecise parameterized complexity of this problem, this implies that b-Coloringparameterized by pathwidth is -hard for all , and resolves theparameterized complexity of -Coloring parameterized by treewidth.<br
On Matrix Superpotential and Three-Component Normal Modes
We consider the supersymmetric quantum mechanics (SUSY QM) with three-
component normal modes for the Bogomol'nyi-Prasad-Sommerfield (BPS) states. An
explicit form of the SUSY QM matrix superpotential is presented and the
corresponding three-component bosonic zero-mode eigenfunction is investigated.Comment: 17 pages, no figure. Paper accepted for publication in Journal of
Physics A: Mathematical and Theoretica
Probing the two-scale-factor universality hypothesis by exact rotation symmetry-breaking mechanism
We probe the two-scale factor universality hypothesis by evaluating, firstly
explicitly and analytically at the one-loop order, the loop quantum corrections
to the amplitude ratios for O() scalar field theories with
rotation symmetry-breaking in three distinct and independent methods in which
the rotation symmetry-breaking mechanism is treated exactly. We show that the
rotation symmetry-breaking amplitude ratios turn out to be identical in the
three methods and equal to their respective rotation symmetry-breaking ones,
although the amplitudes themselves, in general, depend on the method employed
and on the rotation symmetry-breaking parameter. At the end, we show that all
these results can be generalized, through an inductive process based on a
general theorem emerging from the exact calculation, to any loop level and
physically interpreted based on symmetry ideas.Comment: 17 pages, 3 figure
Caracterização da ictiofauna durante as estações de inverno e verão na ressaca da Lagoa dos Índios, Macapá - AP.
Resumo simples
Visitantes florais de Moringa oleifera Lam. na região de Petrolina-PE.
Por ser uma espécie introduzida, este trabalho teve por objetivo verificar as relações desta espécie com seus visitantes florais, identificando os possíveis agentes polinizadores
Determinação do grau crítico de umidade em sementes de Cenostigma tocantinum Ducke e Dipteryx odorata Willd.
Este trabalho teve como objetivo avaliar o comportamento das sementes desta espécie quanto a sensibilidade à desidratação
Structure formation in the presence of dark energy perturbations
We study non-linear structure formation in the presence of dark energy. The
influence of dark energy on the growth of large-scale cosmological structures
is exerted both through its background effect on the expansion rate, and
through its perturbations as well. In order to compute the rate of formation of
massive objects we employ the Spherical Collapse formalism, which we generalize
to include fluids with pressure. We show that the resulting non-linear
evolution equations are identical to the ones obtained in the Pseudo-Newtonian
approach to cosmological perturbations, in the regime where an equation of
state serves to describe both the background pressure relative to density, and
the pressure perturbations relative to the density perturbations as well. We
then consider a wide range of constant and time-dependent equations of state
(including phantom models) parametrized in a standard way, and study their
impact on the non-linear growth of structure. The main effect is the formation
of dark energy structure associated with the dark matter halo: non-phantom
equations of state induce the formation of a dark energy halo, damping the
growth of structures; phantom models, on the other hand, generate dark energy
voids, enhancing structure growth. Finally, we employ the Press-Schechter
formalism to compute how dark energy affects the number of massive objects as a
function of redshift.Comment: 21 pages, 8 figures. Matches published version, with caption of Fig.
6 correcte
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