213 research outputs found

    Symmetry conserving configuration mixing description of odd mass nuclei

    Full text link
    We present a self-consistent theory for the description of the spectroscopic properties of odd nuclei, which includes exact blocking, particle-number and angular-momentum projection, and configuration mixing. In our theory the pairing correlations are treated in a variation-after-projection approach and the triaxial deformation parameters are explicitly considered as generator coordinates. The angular-momentum and particle-number symmetries are exactly recovered. The use of the effective finite-range density-dependent Gogny force in the calculations provides an added value to the theoretical results. We apply the theory to the textbook example of Mg25 and, although this nucleus has been thoroughly studied in the past, we still provide a novel view of nuclear phenomena taking place in this nucleus. We obtain an overall good agreement with the known experimental energies and transition probabilities without any additional parameter such as effective charges. In particular, we clearly identify six bands, two of which we interpret as collective γ bandsThis work was supported by MINECO (Spain) under contract FPA2014-57196-C5-2-P

    An approximation in symmetry conserving configuration mixing calculations

    Full text link
    An approximation is proposed in Beyond mean field calculations to reduce the size of the grid subtended by the generator coordinates by one order of magnitude. We show the quality of the approximation calculating the excitation energies of the titanium isotopes and the E2 transition probabilitiesThis work was supported by the Spanish Ministerio de Economía y Competitividad under contracts FPA2011-29854-C04-04, FPA2014-57196-C5-2-P and BES-2012-05940

    A computational approach to George Boole's discovery of mathematical logic

    Get PDF
    This paper reports a computational model of Boole's discovery of Logic as a part of Mathematics. George Boole (1815–1864) found that the symbols of Logic behaved as algebraic symbols, and he then rebuilt the whole contemporary theory of Logic by the use of methods such as the solution of algebraic equations. Study of the different historical factors that influenced this achievement has served as background for our two main contributions: a computational representation of Boole's Logic before it was mathematized; and a production system, BOOLE2, that rediscovers Logic as a science that behaves exactly as a branch of Mathematics, and that thus validates to some extent the historical explanation. The system's discovery methods are found to be general enough to handle three other cases: two versions of a Geometry due to a contemporary of Boole, and a small subset of the Differential Calculus.Publicad

    Bandwidth selection for kernel density estimation with length-biased data

    Get PDF
    Length-biased data are a particular case of weighted data, which arise in many situations: biomedicine, quality control or epidemiology among others. In this paper we study the theoretical properties of kernel density estimation in the context of length-biased data, proposing two consistent bootstrap methods that we use for bandwidth selection. Apart from the bootstrap bandwidth selectors we suggest a rule-of-thumb. These bandwidth selection proposals are compared with a least-squares cross-validation method. A simulation study is accomplished to understand the behaviour of the procedures in finite samples

    Derivative couplings in gravitational production in the early universe

    Get PDF
    Gravitational particle production in the early universe is due to the coupling of matter fields to curvature. This coupling may include derivative terms that modify the kinetic term. The most general first order action contains derivative couplings to the curvature scalar and to the traceless Ricci tensor, which can be dominant in the case of (pseudo-)Nambu-Goldstone bosons or disformal scalars, such as branons. In the presence of these derivative couplings, the density of produced particles for the adiabatic regime in the de Sitter phase (which mimics inflation) is constant in time and decays with the inverse effective mass (which in turn depends on the coupling to the curvature scalar). In the reheating phase following inflation, the presence of derivative couplings to the background curvature modifies in a nontrivial way the gravitational production even in the perturbative regime. We also show that the two couplings -- to the curvature scalar and to the traceless Ricci tensor -- are drastically different, specially for large masses. In this regime, the production becomes highly sensitive to the former coupling while it becomes independent of the latter.Comment: 24 pages, 6 figure

    Noble gas variation during partial crustal melting and magma ascent processes

    Get PDF
    Noble gas isotopes, although present in trace amounts, are generally more reliable and less ambiguous recorders of their source than the major volatile species. In volcanic settings in particular, this advantage derives from their chemical inertness, as noble gas isotopic and elemental fractionations are strongly coupled to their source and modified only by physical processes during magma ascent and eruption. The Neogene volcano El Hoyazo (Betic Cordillera, SE Spain) is a highly favourable natural laboratory to study the links between partial crustal melting processes occurring at depth and the eruptive products at the surface, because partially melted crustal xenoliths are preserved in silicic lavas. Comparing the noble gas isotopic compositions of xenoliths and lavas has the potential to yield new insights into volatile behaviour during melting processes at inaccessible depths in the crust. At El Hoyazo, noble gases trapped in lava glasses, and the fluid/melt inclusions within xeno- and phenocrysts, provide novel information on: (i) their response to the crustal melting process including mechanisms such as magma mixing (and crustal assimilation) of two endmembers: i.e. the extracted felsic melt from the country metapelitic crust, and the basic-intermediate magma from the underplating in the region. The results reveal significant modification of magmatic noble gases by the interaction with the partially melted crust; (ii) noble gas variations during degassing and magma ascent, showing higher atmospheric influence in the lava samples from shallower depths than in the deeper lavas and minerals; and (iii) higher magmatic influence in crystals of garnet from deeper lava than in both shallower crystals of amphibole, and garnet crystals within the crustal xenoliths. In addition, we find that noble gases in melt inclusions are also likely accumulating in their shrinkage bubbles, and not only remaining dissolved in the melt.Postprint3,51

    An autonomous agent based engineering sales support system.

    Get PDF
    The Internet has emerged as one of the most popular vehicle for disseminating and sharing information through computer networks. A distributed agent-based solution for e-businesses is presented and evaluated in this paper. The system has been developed to help the salesmen, of a construction firm, in their jobs. This business system has a high degree of autonomy, which has been achieved by the use of deliberative agents. A special type of agents has been developed for this particular system. Such agents use a case-base reasoning system to generate their action plans. These agents can be easily constructed from numerical specifications and have the ability of reasoning and adapting to the environmental changes without human supervision. The paper describes in detail both the multiagent based system and the deliberative agents used in it

    High-level information fusion for risk and accidents prevention in pervasive oil industry environments

    Get PDF
    Proceedings of: 12th International Conference on Practical Applications of Agents and Multi-Agent Systems, University of Salamanca (Spain), 4th-6th June, 2014.Information fusion studies theories and methods to effectively combine data from multiple sensors and related information to achieve more specific inferences that could be achieved by using a single, independent sensor. Information fused from sensors and data mining analysis has recently attracted the attention of the research community for real-world applications. In this sense, the deployment of an Intelligent Offshore Oil Industry Environment will help to figure out a risky scenario based on the events occurred in the past related to anomalies and the profile of the current employee (role, location, etc.). In this paper we propose an information fusion model for an intelligent oil environment in which employees are alerted about possible risk situations while their are moving around their working place. The layered architecture, implements a reasoning engine capable of intelligently filtering the context profile of the employee (role, location) for the feature selection of an inter-transaction mining process. Depending on the employee contextual information he will receive intelligent alerts based on the prediction model that use his role and his current location. This model provides the big picture about risk analysis for that employee at that place in that moment.This work was partially funded by CNPq BJT Project 407851/2012-
    corecore