43,631 research outputs found
Inference of Planck action constant by a classical fluctuative postulate holding for stable microscopic and macroscopic dynamical systems
The possibility is discussed of inferring or simulating some aspects of
quantum dynamics by adding classical statistical fluctuations to classical
mechanics. We introduce a general principle of mechanical stability and derive
a necessary condition for classical chaotic fluctuations to affect confined
dynamical systems, on any scale, ranging from microscopic to macroscopic
domains. As a consequence we obtain, both for microscopic and macroscopic
aggregates, dimensional relations defining the minimum unit of action of
individual constituents, yielding in all cases Planck action constant.Comment: 14 pages, no figure
Polarized Deformed Nuclei Studied via Coincidence Polarized Electron Scattering: The case of 21 Ne
Coincidence reactions of the type \svec{A}(\svec{e},e'N)B involving the
scattering of polarized electrons from deformed polarized targets are discussed
within the context of the plane--wave impulse approximation. A general
expression for the polarized spectral function for transitions leaving the
residual nucleus in discrete states is presented. General properties and
angular symmetries exhibited by the polarization observables are discussed in
detail. Results for unpolarized cross sections as well as for polarization
ratios (asymmetries) are obtained for typical quasi--free kinematics. The
dependences of the polarization observables on the bound neutron momentum,
target polarization orientation, nuclear deformation and value of the momentum
transfer are discussed in detail for various different kinematical
situations.Comment: 37 pages in Plain TeX, MIT-CTP-209
Spin Glasses
This is a short review about recent methods and results, mostly for mean
field spin glasses, based on interpolation and comparison schemes. In
particular, the Parisi spontaneous replica symmetry breaking phenomenon is
described in the frame of extended variational principles, Derrida-Ruelle
probability cascades, and overlap locking.Comment: 25 page
Event-driven grammars: Relating abstract and concrete levels of visual languages
The final publication is available at Springer via http://dx.doi.org/10.1007/s10270-007-0051-2In this work we introduce event-driven grammars, a kind of graph grammars that are especially suited for visual modelling environments generated by meta-modelling. Rules in these grammars may be triggered by user actions (such as creating, editing or connecting elements) and in their turn may trigger other user-interface events. Their combination with triple graph transformation systems allows constructing and checking the consistency of the abstract syntax graph while the user is building the concrete syntax model, as well as managing the layout of the concrete syntax representation. As an example of these concepts, we show the definition of a modelling environment for UML sequence diagrams. A discussion is also presented of methodological aspects for the generation of environments for visual languages with multiple views, its connection with triple graph grammars, the formalization of the latter in the double pushout approach and its extension with an inheritance concept.This work has been partially sponsored by the Spanish Ministry of Education and Science with projects MOSAIC (TSI2005-08225-C07-06) and MODUWEB (TIN 2006-09678)
An algebraic semantics for QVT-relations check-only transformations
Fundamenta Informaticae, 114 1, Juan de Lara, Esther Guerra, An algebraic semantics for QVT-relations check-only transformations, 73-101, Copyright 2012, with permission from IOS PressQVT is the standard for model transformation defined by the OMG in the context of the Model-Driven Architecture. It is made of several transformation languages. Among them, QVT-Relations is the one with the highest level of abstraction, as it permits developing bidirectional transformations in a declarative, relational style. Unfortunately, the standard only provides a semiformal description of its semantics, which hinders analysis and has given rise to ambiguities in existing tool implementations. In order to improve this situation, we propose a formal, algebraic semantics for QVT-Relations check-only transformations, defining a notion of satisfaction of QVT-Relations specifications by models.This work has been supported by the Spanish Ministry of Science and Innovation with projects METEORIC (TIN2008-02081) and Go Lite (TIN2011-24139), and by the R&D program of the Community of Madrid with project “e-Madrid” (S2009/TIC-1650)
- …