Anharmonic effects in magnetoelastic chains

We describe a new mechanism leading to the formation of rational magnetization plateau phases, which is mainly due to the anharmonic spin-phonon coupling. This anharmonicity produces plateaux in the magnetization curve at unexpected values of the magnetization without explicit magnetic frustration in the Hamiltonian and without an explicit breaking of the translational symmetry. These plateau phases are accompanied by magneto-elastic deformations which are not present in the harmonic case.Comment: 5 pages, 3 figure

Enhanced Higgs boson production and avoidance of CP-violation and FCNC in the MPP inspired 2HDM

The multiple point principle (MPP) can be used to suppress non--diagonal flavour transitions and CP violation in the two Higgs doublet extension of the standard model. We discuss the quasi--fixed point scenario in the MPP inspired two Higgs doublet model which leads to the enhanced production of Higgs particles at the LHC if the MPP scale is low.Comment: Talk given at the 2007 Europhysics Conference on High Energy Physics, Manchester, England, 19-25 July 2007, CERN preprint number added, references update

Elementary solution to the time-independent quantum navigation problem

A quantum navigation problem concerns the identification of a time-optimal Hamiltonian that realizes a required quantum process or task, under the influence of a prevailing ‘background’ Hamiltonian that cannot be manipulated. When the task is to transform one quantum state into another, finding the solution in closed form to the problem is nontrivial even in the case of timeindependent Hamiltonians. An elementary solution, based on trigonometric analysis, is found here when the Hilbert space dimension is two. Difficulties arising from generalizations to higher-dimensional systems are discussed

Negative Specific Heat in a Quasi-2D Generalized Vorticity Model

Negative specific heat is a dramatic phenomenon where processes decrease in temperature when adding energy. It has been observed in gravo-thermal collapse of globular clusters. We now report finding this phenomenon in bundles of nearly parallel, periodic, single-sign generalized vortex filaments in the electron magnetohydrodynamic (EMH) model for the unbounded plane under strong magnetic confinement. We derive the specific heat using a steepest descent method and a mean field property. Our derivations show that as temperature increases, the overall size of the system increases exponentially and the energy drops. The implication of negative specific heat is a runaway reaction, resulting in a collapsing inner core surrounded by an expanding halo of filaments.Comment: 12 pages, 3 figures; updated with revision

Teaching research methods: Introducing a psychogeographical approach

This paper explores teaching business students research methods using a psychogeographical approach, specifically the technique of dérive. It responds to calls for new ways of teaching in higher education and addresses the dearth of literature on teaching undergraduate business students qualitative research methods. Psychogeography challenges the dominance of questionnaires and interviews, introduces students to data variety, problematizes notions of success and illuminates the importance of observation and location. Using two studies with undergraduate students, the authors emphasize place and setting, the perception of purpose, the choice of data, criteria of success and the value of guided reflection and self-reflection in students’ learning. Additionally the data reflect on the way students perceive research about management and the nature of management itself. The paper concludes that the deployment of psychogeography to teach business research methods although complex and fraught with difficulty is nevertheless viable, educationally productive and worthy of further research

The elliptic genus of Calabi-Yau 3- and 4-folds, product formulae and generalized Kac-Moody algebras

In this paper the elliptic genus for a general Calabi-Yau fourfold is derived. The recent work of Kawai calculating N=2 heterotic string one-loop threshold corrections with a Wilson line turned on is extended to a similar computation where K3 is replaced by a general Calabi-Yau 3- or 4-fold. In all cases there seems to be a generalized Kac-Moody algebra involved, whose denominator formula appears in the result.Comment: 10 pages, latex, no figure

Quantum Machine and SR Approach: a Unified Model

The Geneva-Brussels approach to quantum mechanics (QM) and the semantic realism (SR) nonstandard interpretation of QM exhibit some common features and some deep conceptual differences. We discuss in this paper two elementary models provided in the two approaches as intuitive supports to general reasonings and as a proof of consistency of general assumptions, and show that Aerts' quantum machine can be embodied into a macroscopic version of the microscopic SR model, overcoming the seeming incompatibility between the two models. This result provides some hints for the construction of a unified perspective in which the two approaches can be properly placed.Comment: 21 pages, 5 figures. Introduction and Conclusions improved, minor corrections in several sections. Accepted for publication in Foundations of Physic

Crisis as a plague on organisation: Defoe and A Journal of the Plague Year

Purpose – The purpose of this paper is to enrich the understanding of current models of organisational response to crises and offer additional perspectives on some of these models. It is also intended to confirm the value of fiction as a truth-seeking and hermeneutic device for enriching the imagination. Design/methodology/approach – The study uses Daniel Defoe’s 1722 novel A Journal of the Plague Year to draw parallels between his portrayal of the London Great Plague of 1665 and the management of modern-day crises. Defoe uses London’s ordeal of the Great Plague to advise those subjected to future crises. Through his representation of plague-ridden streets, Defoe shows stakeholders acting in ways described in current crisis management literature. Findings – The authors note how the management of the Plague crisis was unsuccessful and they challenge the very idea of managing a true crisis. The authors are able to illustrate and offer refinements to the Pearson and Clair (1998) and Janes (2010) models of crisis management as well as confirming the value of their constructs across a lapse of centuries. Research limitations/implications – Although it is an examination of a single novel, the findings suggest value in conceptualising organisational crises in innovative and more imaginative ways. Originality/value – It confirms the heuristic value of using fiction to understand organisational change and adds value to current model