Hidden Kondo Effect in a Correlated Electron Chain

We develop a general Bethe Ansatz formalism for diagonalizing an integrable model of a magnetic impurity of arbitrary spin coupled ferro- or antiferromagnetically to a chain of interacting electrons. The method is applied to an open chain, with the exact solution revealing a ``hidden'' Kondo effect driven by forward electron scattering off the impurity. We argue that the so-called ``operator reflection matrices'' proposed in recent Bethe Ansatz studies of related models emulate only forward electron-impurity scattering which may explain the absence of complete Kondo screening for certain values of the impurity-electron coupling in these models.Comment: 5 pages, RevTex; to appear in Phys. Rev. Let

The IGEX experiment revisited: a response to the critique of Klapdor-Kleingrothaus,Dietz, and Krivosheina

This paper is a response to the article "Critical View to" the IGEX neutrinoless double-beta decay experiment..."published in Phys. Rev.D, Volume 65 (2002) 092007," by H.V.Klapdor-Kleingrothaus, A. Dietz, and I.V.Krivosheina, published as preprint hep-ph/0403056. The criticisms are confronted, and the questions raised are answered. We demonstrate that the lower limit quoted by IGEX, for the half life of Ge-76 neutrinoless double beta decay, 1.57x10**25 y, is correct and that there was no "arithmetical error"-as claimed in the " Critical Review" article

The Naming Game in Social Networks: Community Formation and Consensus Engineering

We study the dynamics of the Naming Game [Baronchelli et al., (2006) J. Stat. Mech.: Theory Exp. P06014] in empirical social networks. This stylized agent-based model captures essential features of agreement dynamics in a network of autonomous agents, corresponding to the development of shared classification schemes in a network of artificial agents or opinion spreading and social dynamics in social networks. Our study focuses on the impact that communities in the underlying social graphs have on the outcome of the agreement process. We find that networks with strong community structure hinder the system from reaching global agreement; the evolution of the Naming Game in these networks maintains clusters of coexisting opinions indefinitely. Further, we investigate agent-based network strategies to facilitate convergence to global consensus.Comment: The original publication is available at http://www.springerlink.com/content/70370l311m1u0ng3

Native-English-Speaking Teachers:Disconnections Between Theory, Research, and Practice

Native-English-speaking teachers (NESTs) have long been in demand for perceived benefits of the skills they bring to the classroom. However, the notion that native speakers provide the best models of the target language and thus make the best teachers of the language has been criticised in the literature. This article reports on the disconnection between academic literature on NESTs and the realities they report. Drawing on data from an investigation into NEST schemes globally, the article suggests that lived classroom experiences of NESTs are complex, They are also often bilingual, experienced, and qualified, and regard local English teachers (LETs) they work with as experts and in control of how English is practised in the classroom. These characteristics contrast with much of the academic literature, which explores the concept of native speakerism, which tends to view NESTs negatively. The article proposes that one reason for the disconnection between theory and practice is the parallel lives of researchers and teachers, whether NESTs or LETs. Thus, each group’s realities and concerns are not always understood by the other. The article suggests that a substantial group of bilingual and bicultural NESTs consider the country where work home, so future theorisations of NESTs and native speakerism should take account of these teachers

Gravitating discs around black holes

Fluid discs and tori around black holes are discussed within different approaches and with the emphasis on the role of disc gravity. First reviewed are the prospects of investigating the gravitational field of a black hole--disc system by analytical solutions of stationary, axially symmetric Einstein's equations. Then, more detailed considerations are focused to middle and outer parts of extended disc-like configurations where relativistic effects are small and the Newtonian description is adequate. Within general relativity, only a static case has been analysed in detail. Results are often very inspiring, however, simplifying assumptions must be imposed: ad hoc profiles of the disc density are commonly assumed and the effects of frame-dragging and completely lacking. Astrophysical discs (e.g. accretion discs in active galactic nuclei) typically extend far beyond the relativistic domain and are fairly diluted. However, self-gravity is still essential for their structure and evolution, as well as for their radiation emission and the impact on the environment around. For example, a nuclear star cluster in a galactic centre may bear various imprints of mutual star--disc interactions, which can be recognised in observational properties, such as the relation between the central mass and stellar velocity dispersion.Comment: Accepted for publication in CQG; high-resolution figures will be available from http://www.iop.org/EJ/journal/CQ

Research on optical core networks in the e-Photon/ONe network of excellence

This papers reports the advances in Optical Core networks research coordinated in the framework of the e-Photon/ONe and e-Photon/ONe+ networks of excellence