90 research outputs found
Modular Groups, Visibility Diagram and Quantum Hall Effect
We consider the action of the modular group on the set of
positive rational fractions. From this, we derive a model for a classification
of fractional (as well as integer) Hall states which can be visualized on two
``visibility" diagrams, the first one being associated with even denominator
fractions whereas the second one is linked to odd denominator fractions. We use
this model to predict, among some interesting physical quantities, the relative
ratios of the width of the different transversal resistivity plateaus. A
numerical simulation of the tranversal resistivity plot based on this last
prediction fits well with the present experimental data.Comment: 17 pages, plain TeX, 4 eps figures included (macro epsf.tex), 1
figure available from reques
Arnol'd Tongues and Quantum Accelerator Modes
The stable periodic orbits of an area-preserving map on the 2-torus, which is
formally a variant of the Standard Map, have been shown to explain the quantum
accelerator modes that were discovered in experiments with laser-cooled atoms.
We show that their parametric dependence exhibits Arnol'd-like tongues and
perform a perturbative analysis of such structures. We thus explain the
arithmetical organisation of the accelerator modes and discuss experimental
implications thereof.Comment: 20 pages, 6 encapsulated postscript figure
A song and dance: branded entertainment and mobile promotion
This article considers the rise of branded entertainment within the contemporary marketing and media environment. Specifically, it examines how mobile phone marketing in the UK has sought to engage consumers and perform the social use of mobile technology through multimedia ad campaigns with an inscribed entertainment value. Focusing on brand campaigns for 3G mobile services that borrow explicitly from reality television (T-Mobile) and Hollywood film (Orange), the article explores the concept of branded entertainment in relation to the âpopular imaginationâ of mobile communication in the late 2000s. In doing so, it examines the particular relation of flash mobs to the production of brand community
William Huddesford (1732â1772): his role in reanimating the Ashmolean Museum, his collections, researches and support network
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