Hierarchical Structure of Azbel-Hofstader Problem: Strings and loose ends of Bethe Ansatz

We present numerical evidence that solutions of the Bethe Ansatz equations for a Bloch particle in an incommensurate magnetic field (Azbel-Hofstadter or AH model), consist of complexes-"strings". String solutions are well-known from integrable field theories. They become asymptotically exact in the thermodynamic limit. The string solutions for the AH model are exact in the incommensurate limit, where the flux through the unit cell is an irrational number in units of the elementary flux quantum. We introduce the notion of the integral spectral flow and conjecture a hierarchical tree for the problem. The hierarchical tree describes the topology of the singular continuous spectrum of the problem. We show that the string content of a state is determined uniquely by the rate of the spectral flow (Hall conductance) along the tree. We identify the Hall conductances with the set of Takahashi-Suzuki numbers (the set of dimensions of the irreducible representations of $U_q(sl_2)$ with definite parity). In this paper we consider the approximation of noninteracting strings. It provides the gap distribution function, the mean scaling dimension for the bandwidths and gives a very good approximation for some wave functions which even captures their multifractal properties. However, it misses the multifractal character of the spectrum.Comment: revtex, 30 pages, 6 Figs, 8 postscript files are enclosed, important references are adde

Axially symmetric Hartree-Fock-Bogoliubov Calculations for Nuclei Near the Drip-Lines

Nuclei far from stability are studied by solving the Hartree-Fock-Bogoliubov (HFB) equations, which describe the self-consistent mean field theory with pairing interaction. Calculations for even-even nuclei are carried out on two-dimensional axially symmetric lattice, in coordinate space. The quasiparticle continuum wavefunctions are considered for energies up to 60 MeV. Nuclei near the drip lines have a strong coupling between weakly bound states and the particle continuum. This method gives a proper description of the ground state properties of such nuclei. High accuracy is achieved by representing the operators and wavefunctions using the technique of basis-splines. The detailed representation of the HFB equations in cylindrical coordinates is discussed. Calculations of observables for nuclei near the neutron drip line are presented to demonstrate the reliability of the method.Comment: 13 pages, 4 figures. Submitted to Physical Review C on 05/08/02. Revised on Dec/0

Anticipated regret to increase uptake of colorectal cancer screening (ARTICS):a randomised controlled trial

Objective. Screening is key to early detection of colorectal cancer. Our aim was to determine whether a simple anticipated regret (AR) intervention could increase colorectal cancer screening uptake. Methods. We conducted a randomised controlled trial of a simple, questionnaire-based AR intervention, delivered alongside existing pre-notification letters. 60,000 adults aged 50-74 from the Scottish National Screening programme were randomised to: 1) no questionnaire (control), 2) Health Locus of Control questionnaire (HLOC) or 3) HLOC plus anticipated regret questionnaire (AR). Primary outcome was guaiac Faecal Occult Blood Test (FOBT) return. Secondary outcomes included intention to return test kit and perceived disgust (ICK). Results. 59,366 people were analysed as allocated (Intentionto- treat (ITT)); there were no overall differences between treatment groups on FOBT uptake (control: 57.3%, HLOC: 56.9%, AR: 57.4%). 13,645 (34.2%) people returned questionnaires. Analysis of the secondary questionnaire measures showed that AR had an indirect effect on FOBT uptake via intention, whilst ICK had a direct effect on FOBT uptake over and above intention. The effect of AR on FOBT uptake was also moderated by intention strength: for less than strong intenders only, uptake was 4.2% higher in the AR (84.6%) versus the HLOC group (80.4%) (95% CI for difference (2.0, 6.5)). Conclusion. The findings show that psychological concepts including anticipated regret and perceived disgust (ICK) are important factors in determining FOBT uptake. However, there was no simple effect of the AR intervention in the ITT. We conclude that exposure to AR in those with low intentions may be required to increase FOBT uptake. Current controlled trials: www.controlledtrials. com number: ISRCTN74986452

Schottky barrier heights at polar metal/semiconductor interfaces

Using a first-principle pseudopotential approach, we have investigated the Schottky barrier heights of abrupt Al/Ge, Al/GaAs, Al/AlAs, and Al/ZnSe (100) junctions, and their dependence on the semiconductor chemical composition and surface termination. A model based on linear-response theory is developed, which provides a simple, yet accurate description of the barrier-height variations with the chemical composition of the semiconductor. The larger barrier values found for the anion- than for the cation-terminated surfaces are explained in terms of the screened charge of the polar semiconductor surface and its image charge at the metal surface. Atomic scale computations show how the classical image charge concept, valid for charges placed at large distances from the metal, extends to distances shorter than the decay length of the metal-induced-gap states.Comment: REVTeX 4, 11 pages, 6 EPS figure

Teaching modern foreign languages in multilingual classrooms: an examination of Key Stage 2 teachers’ experiences

The statutory inclusion of modern foreign languages (MFL) into the Key Stage 2 curriculum in England in 2014 aimed to raise the language skills of younger learners in preparation for their secondary education. This change to the curriculum has occurred at a time in which the linguistic diversity within primary schools across the country has been consistently increasing. This study used Interpretative Phenomenological Analysis to qualitatively examine the impact of the curriculum change on teachers implementing it in multilingual classrooms in Greater Manchester. Six teachers with varying experience in teaching MFL participated in semistructured interviews focussing on different aspects of the curriculum change. This paper focuses on the teaching of MFL, as well as on teachers’ perceptions of English as an Additional Language (EAL) pupils’ aptitude for language learning in comparison to their monolingual peers. The superordinate themes identified from the data included the inconsistent delivery of MFL in primary schools, and the role of multilingual classrooms as opportunities for augmented MFL provision. The findings from this study will have implications for teachers, head teachers, and policy-makers regarding the effectiveness of the initial implementation of MFL into the primary curriculum, with specific reference to the EAL school population

Placing Joseph Banks in the North Pacific

The South Pacific was a fulcrum of Joseph Banks's maritime world and global networks. The North Pacific was a distance and intangible fringe. This article is concerned with how Banks should be ‘placed’ in the North Pacific. It tracks how Banks's activities have been delineated in terms of languages and categories of global and local, and centre and margin, and then considers the historical and geographical specifics apposite to his connection to the North Pacific. In this setting, ideas of place (as location and assignment) and capital (as a circulatory and everyday practice of exchange and opportunism) come into view and question the distinction between science and commerce in Banks historiography. The article considers a diverse group of non-Indigenous figures – explorers, traders, cartographers, scientists, collectors – operating in the North Pacific in the 1780s and 1790s whose initiatives and missives passed across Banks's desk, and assesses their place in Banks's archive by drawing on Peter Sloterdijk's ideas about the interiorising and exteriorising logic of capital.PostprintPeer reviewe

The politics of evidence: methodologies for understanding the global land rush

Since the most recent ‘land rush’ precipitated by the convergent ‘crises’ of fuel, feed and food in 2007-08, the debate on the consequences of land investments has been massively heightened, with widespread media coverage, policy commentary and civil society engagement. The ‘land rush’ of recent years has been accompanied by a ‘literature rush’, with a fast-growing body of reports, articles, tables and books with varied purposes, metrics and methods. ‘Land grabbing’ is now a hot political topic around the world, discussed amongst the highest circles. This is why getting the facts right is really important, and having effective methodologies is crucial. Several global initiatives have set out to aggregate information on land deals, and to describe their scale, character and distribution. All have contributed to building a better picture of the phenomenon, but all have struggled with methodology. This JPS Forum identifies a profound uncertainty about what it is that is being counted, questions methods used to collate and aggregate ‘land grabs’, and calls for a second phase of land grab research which abandons the aim of deriving total numbers of hectares in favour of more specific, grounded and transparent methods.ESR

Search for supersymmetry with a dominant R-parity violating LQDbar couplings in e+e- collisions at centre-of-mass energies of 130GeV to 172 GeV

A search for pair-production of supersymmetric particles under the assumption that R-parity is violated via a dominant LQDbar coupling has been performed using the data collected by ALEPH at centre-of-mass energies of 130-172 GeV. The observed candidate events in the data are in agreement with the Standard Model expectation. This result is translated into lower limits on the masses of charginos, neutralinos, sleptons, sneutrinos and squarks. For instance, for m_0=500 GeV/c^2 and tan(beta)=sqrt(2) charginos with masses smaller than 81 GeV/c^2 and neutralinos with masses smaller than 29 GeV/c^2 are excluded at the 95% confidence level for any generation structure of the LQDbar coupling.Comment: 32 pages, 30 figure