941 research outputs found
Infinite matrix product states, Conformal Field Theory and the Haldane-Shastry model
We generalize the Matrix Product States method using the chiral vertex
operators of Conformal Field Theory and apply it to study the ground states of
the XXZ spin chain, the J1-J2 model and random Heisenberg models. We compute
the overlap with the exact wave functions, spin-spin correlators and the Renyi
entropy, showing that critical systems can be described by this method. For
rotational invariant ansatzs we construct an inhomogenous extension of the
Haldane-Shastry model with long range exchange interactions.Comment: 5 pages, 4 figures, 1 reference adde
An integration of partial evaluation in a generic abstract interpretation framework
Information generated by abstract interpreters has long been
used to perform program specialization. Additionally, if the
abstract interpreter generates a multivariant analysis, it is also possible to perform múltiple specialization. Information about valúes of variables is propagated by simulating program execution and performing fixpoint computations for recursive calis. In contrast, traditional partial evaluators (mainly) use unfolding for both propagating valúes of variables and transforming the program. It is known that abstract interpretation is a better technique for propagating success valúes than unfolding. However, the program transformations induced by unfolding may lead to important optimizations which are not directly achievable in the existing frameworks for múltiple specialization based on abstract interpretation. The aim of this work is to devise a specialization framework which integrates the better information propagation of abstract interpretation with the powerful program transformations performed by partial evaluation, and which can be implemented via small modifications to existing generic abstract interpreters. With this aim, we will relate top-down abstract interpretation with traditional concepts in partial evaluation and sketch how the sophisticated techniques developed for controlling partial evaluation can be adapted to the proposed specialization framework. We conclude that there can be both practical and conceptual advantages in the proposed integration of partial evaluation
and abstract interpretation
Angular Inflation from Supergravity
We study supergravity inflationary models where inflation is produced along
the angular direction. For this we express the scalar component of a chiral
superfield in terms of the radial and the angular components. We then express
the supergravity potential in a form particularly simple for calculations
involving polynomial expressions for the superpotential and Kahler potential.
We show for a simple Polonyi model the angular direction may give rise to a
stage of inflation when the radial field is fixed to its minimum. We obtain
analytical expressions for all the relevant inflationary quantities and discuss
the possibility of supersymmetry breaking in the radial direction while
inflating by the angular component.Comment: 7 pages, one figure. Final version. Title changed, two figures
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Identidad profesional y conocimiento matemático para la enseñanza de maestros en formación
En este estudio se pretende obtener una mayor comprensión sobre la identidad profesional en formación de estudiantes para maestro y las implicaciones para los programas de formación del profesorado. Se indaga sobre las reflexiones realizadas por estudiantes para maestro de educación primaria concernientes a sus experiencias relativas a la enseñanza y aprendizaje de las matemáticas y a conocimientos que estiman necesarios para enseñar matemáticas. Los resultados obtenidos revelan los aspectos que estos estudiantes destacan como elementos constitutivos de la identidad profesional del maestro haciendo mención a los componentes propios del proceso de enseñanza y aprendizaje de las matemáticas. Se propone una aproximación de la caracterización de la identidad profesional a través del conocimiento matemático para la enseñanza
Hysteretic nonequilibrium Ising-Bloch transition
We show that a parametrically driven cubic-quintic complex Ginzburg-Landau
equation exhibits a hysteretic nonequilibrium Ising-Bloch transition for large
enough quintic nonlinearity. These results help to understand the recent
experimental observation of this pheomenon [A. Esteban-Martin et al., Phys.
Rev. Lett. 94, 223903 (2005)].Comment: 3 pages + six figure
Phase-locking of a Nonlinear Optical Cavity via Rocking: Transmuting Vortices into Phase Patterns
We report experimental observation of the conversion of a phase-invariant
nonlinear system into a phase-locked one via the mechanism of rocking [G. J. de
Valcarcel and K. Staliunas, Phys. Rev. E 67, 026604 (2003)]. This conversion
results in that vortices of the phase-invariant system are being replaced by
phase patterns such as domain walls. The experiment is carried out on a
photorefractive oscillator in two-wave mixing configuration.A model for the
experimental device is given that reproduces the observed behavior.Comment: 9 pages and 4 figure
Towards Integrating Partial Evaluation in a Specialization Framework based on Generic Abstract Interpretation
Abstract is not availabl
Squeezing spectra from s-ordered quasiprobability distributions. Application to dispersive optical bistability
It is well known that the squeezing spectrum of the field exiting a nonlinear
cavity can be directly obtained from the fluctuation spectrum of normally
ordered products of creation and annihilation operators of the cavity mode. In
this article we show that the output field squeezing spectrum can be derived
also by combining the fluctuation spectra of any pair of s-ordered products of
creation and annihilation operators. The interesting result is that the
spectrum obtained in this way from the linearized Langevin equations is exact,
and this occurs in spite of the fact that no s-ordered quasiprobability
distribution verifies a true Fokker-Planck equation, i.e., the Langevin
equations used for deriving the squeezing spectrum are not exact. The
(linearized) intracavity squeezing obtained from any s-ordered distribution is
also exact. These results are exemplified in the problem of dispersive optical
bistability.Comment: 15 pages, no figures, to be published in Journal of Modern Optic
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