Gauge Invariance and Second Class Constraints in 3-D Linearized Gravity

A recently introduced approach for the dynamical analysis and quantization of field theoretical models with second class constraints is ilustrated applied to linearized gravity in 3-D. The canonical structure of two different models of linerized gravity in 3-D, the intermediate and the self dual models, is discussed in detail. It is shown that the first order self dual model whose constraints are all second class may be regarded as a gauge fixed version of the second order gauge invariant intermediate model. In particular it is shown how to construct the gauge invariant hamiltonian of the intermediate model starting from the one of the self dual model. The relation with the t opologically massive linearized gravity is also discussed.Comment: 11 pages, SB-F-93-21

Long and short-term effects of customisation on the service operations strategy.

This study has a twofold objectivc. First, we attempt to promote an understanding of the relationship between the design of Service Operations Strategics and their implementation, as they are driven by the customisation efforts. Seeond, we study the extent to which such service orientation may have two different forms, depending upon whether a company focuses on services that may have long-term or short-term effects on the customer nature. Consequently, a company aiming at raising its quality levels, and therefore its performance, should design and implement its Service Operations Strategy, mirroring the scrvicc oricntation of the firm. We suggest four dimensions (Time, Space, Scale and Scope), which contribute towards explaining the two mentioned approaches. This may address the process of implementation of the Serviee Operations Strategy.service operations; operations strategy; new service development process; marketing / operations interface; service-positioning matrix; customisation; service quality;

Core excitation effects in halo nuclei using a transformed oscillator basis

A recent generalization of the Transformed Harmonic Oscillator basis, intended to consider core excitations in the structure of one nucleon halo nuclei, is applied to the break up of 11Be. The reaction studied is 11Be+208Pb at 69 MeV/nucleon. The experimental set up is designed to ensure pure dipole Coulomb excitations. Making use of the Equivalent Photon Method and the electromagnetic transition probabilities obtained with the transformed oscillator basis, a relevant contribution of the quadrupole excitations of the core is found. The inclusion of core excitations is, therefore, necessary for the correct extraction of the dipole electromagnetic transition probability of halo nuclei.Ministerio de Ciencia e Innovación FIS2011-28738-c02-01, FPA2009- 07653, FPA2009-08848, CSD2007-00042Junta de Andalucía FQM160, P07-FQM-0289

Learning definite Horn formulas from closure queries

A definite Horn theory is a set of n-dimensional Boolean vectors whose characteristic function is expressible as a definite Horn formula, that is, as conjunction of definite Horn clauses. The class of definite Horn theories is known to be learnable under different query learning settings, such as learning from membership and equivalence queries or learning from entailment. We propose yet a different type of query: the closure query. Closure queries are a natural extension of membership queries and also a variant, appropriate in the context of definite Horn formulas, of the so-called correction queries. We present an algorithm that learns conjunctions of definite Horn clauses in polynomial time, using closure and equivalence queries, and show how it relates to the canonical Guigues–Duquenne basis for implicational systems. We also show how the different query models mentioned relate to each other by either showing full-fledged reductions by means of query simulation (where possible), or by showing their connections in the context of particular algorithms that use them for learning definite Horn formulas.Peer ReviewedPostprint (author's final draft

Stabilization method in two-body systems with core excitations

The validity of the stabilization method in core+valence systems including the possibility of exciting the core is studied. A pseudostate method, based on the transformed harmonic oscillator basis, is extended to include the core degrees of freedom. The method is applied to the case of 11Be structure considering the 0+ ground state and the 2+ first excited state of the 10Be core. The stabilization method is defined in terms of one parameter that can be chosen either discrete or continuous. In the application to 11Be, both cases are analyzed.Ministerio de Ciencia e Innovación FIS2011-28738-c02-01, FPA2009-07653, FPA2009-08848, CSD2007-00042Junta de Andalucía FQM160, P07-FQM-0289

Jóvenes sin etiqueta

Jóvenes sin etiqueta, cuenta la experiencia de una estudiante de la Unidad Educativa Técnico Salesiano, quien fue participe del Modelo de Naciones Unidas, el mismo que les impulsó a desarrollar habilidades en investigación, documentación, redacción, oratoria, resolución de problemas y conflictos, construcción de consensos, acuerdos y cooperación