2,776,048 research outputs found
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
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