Precision determination of the pi-N scattering lengths and the charged pi-NN coupling constant

We critically evaluate the isovector GMO sumrule for the charged $\pi N N$ coupling constant using recent precision data from $\pi ^-$p and $\pi^-$d atoms and with careful attention to systematic errors. From the $\pi ^-$d scattering length we deduce the pion-proton scattering lengths ${1/2}(a_{\pi ^-p}+a_{\pi ^-n})=(-20\pm 6$(statistic)$\pm 10$ (systematic))~$\cdot 10^{-4}m_{\pi_c}^{-1}$ and ${1/2}(a_{\pi ^-p}-a_{\pi ^-n})=(903 \pm 14)\cdot 10^{-4}m_{\pi_c}^{-1}$. From this a direct evaluation gives $g^2_c(GMO)/4\pi =14.20\pm 0.07$(statistic)$\pm 0.13$(systematic) or $f^2_c/4\pi= 0.0786\pm 0.0008$.Comment: 4 pages, 1 figure, latex and postscript; invited talk at PANIC99; to appear in Nucl. Phys. A; changed notation: g^2 and f^2 replaced by conventional g^2/4\pi and f^2/4\p

The Pion-Nucleon coupling constant from np charge exchange scattering

A novel extrapolation method has been used to deduce the charged Pion-Nucleon coupling constant from backward $np$ differential scattering cross sections. We applied it to new measurements performed at 162 MeV at the The Svedberg Laboratory in Uppsala. In the angular range $150^\circ-180^\circ$, the carefully normalized data are steeper than those of most previous measurements. The extracted value, $g^2_{\pi^\pm} = 14.52 \pm 0.26$, in good agreement with the classical value, is higher than those determined in recent nucleon-nucleon partial-wave analyses.Comment: 6 pages, 3 encapsulated figures, epsfig, menu97.cls (included

A useful logical semantics of UML for querying and checking UML class diagram

Date du colloque : 01/2009International audienc

Transitions-based system: A relevant use case

International audienc

Using UML Class Diagram as a Knowledge Engineering Tool

Date du colloque : 05/2000International audienc

Aperçus de recherche : interroger efficacement un ensemble de bases RDF

In the context of information retrieval in the Web of Data, we propose a kind of compact version of a RDF triplestore, that acts as an overview on this base of RDF triples. An overview is not only more compact that the initial triplestore, but also SPARQL can be used on it. An overview is built in such a way that if a SPARQL query on overview has no result, then there is no result too to this query into the initial triplestore. So, querying overviews is a more efficient solution than querying the whole triplestores when the query has often no result from these RDF databases. It is usually the case when a user query triplestores on the web of data. Our solution has been evaluated using RDF bases extracted from DBPedia and queries extracted either from the most common used on DBPedia or because of their resolution complexity

How precisely can we determine the pion-nucleon coupling constant from the isovector GMO sum rule?

The isovector GMO sum rule for zero energy forward pion-nucleon scattering is critically studied to obtain the charged pion-nucleon coupling constant using the precise negatively charged pion-proton and pion-deuteron scattering lengths deduced recently from pionic atom experiments. This direct determination leads to a pseudoscalar charged pion-nucleon coupling constant of 14.23 +- 0.09 (statistic) +- 0.17 (systematic). We obtain also accurate values for the pion-nucleon scattering lengths.Comment: Talk given at the Eighth International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon, Zuoz, Switzerland, August 15-21, 1999, 5 pages, 2 figures, file menu.cls include

Une synthèse des modèles de représentation des connaissances à base de Graphes Conceptuels et OWL

Nous présentons et comparons deux approches de modélisation, formelles et concrètes, pour représenter et manipuler des connaissances d’un domaine. Le modèle des graphes conceptuels permet de modéliser des connaissances en terme de graphes, basés sur un support. Cette approche de modélisation est intensionnelle, est munie d’une sémantique en logique du premier ordre, et fait l’hypothèse d’un monde fermé pour ses raisonnements. Le langage OWL permet de décrire des ontologies et des faits sur le Web, suivant une approche de modélisation extensionnelle. Il possède une sémantique issue des logiques de descriptions, et fait l’hypothèse d’un monde ouvert pour ses raisonnements

The physical and chemical properties of heteronanotubes

Carbon nanotubes undoubtedly take a leading position in nanotechnology research owing to their well-known outstanding structural and electronic properties. Inspired by this, hybrid and functionalized tubular structures have been constructed via several modification paths that involve the presence of molecules, generation of defects, and partial or full replacement of the carbon atoms, always maintaining a nanotube structure. The possibilities are countless. However, this review is mainly dedicated to giving a fundamental insight into the concepts behind wall modification, doping, and formation of a carbon nanotube structure. Theoretical concepts and experimental achievements ranging from carbon nanotubes with low B or N doping to the new physics behind boron nitride nanotubes are covered. Furthermore, special attention is devoted to the bulk and local characterization tools employed with these materials, their suitability and limitations. The theoretical approaches to describing the physical and chemical properties of heteronanotubes are objectively analyzed versus the materials available at this moment

A question of balance: The benefits of pattern-recognition when solving problems in a complex domain

This is the accepted manuscript version of the following article: M. Lloyd-Kelly, F. Gobet, and Peter C. R. Lane, “A Question of Balance The Benefits of Pattern-Recognition when Solving Problems in a Complex Domain”, LNCS Transactions on Computational Collective Intelligence, Vol. XX, 2015. The final published version is available at: http://www.springer.com/gb/book/9783319275420 © 2015 Springer International Publishing.The dual-process theory of human cognition proposes the existence of two systems for decision-making: a slower, deliberative,problem-solving system and a quicker, reactive, pattern-recognition system. We alter the balance of these systems in a number of computational simulations using three types of agent equipped with a novel, hybrid, human-like cognitive architecture. These agents are situated in the stochastic, multi-agent Tileworld domain, whose complexity can be precisely controlled and widely varied. We explore how agent performance is affected by different balances of problem-solving and pattern-recognition, and conduct a sensitivity analysis upon key pattern-recognition system variables. Results indicate that pattern-recognition improves agent performance by as much as 36.5 % and, if a balance is struck with particular pattern-recognition components to promote pattern-recognition use, performance can be further improved by up to 3.6 %. This research is of interest for studies of expert behaviour in particular, and AI in general.Peer reviewedFinal Accepted Versio