464 research outputs found

    Quantum phases of a chain of strongly interacting anyons

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    We study a strongly interacting chain of anyons with fusion rules determined by SO(5)2. The phase portrait is identified with a combination of numerical and analytical techniques. Several critical phases with different central charges and their corresponding transitions identified.Comment: 5 pages, 4 figure

    Acute military psychiatric casualties from the war in Iraq

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    Background: The view that most military personnel evacuated from war zones are suffering from combat stress reactions, or are otherwise traumatised by the horrors of war, has an impact on all aspects of military psychiatry. Aims: To delineate the reasons for psychiatric aeromedical evacuation from Iraq from the start of build-up of UK forces in January 2003 until the end of October that year, 6 months after the end of formal hostilities. Method: A retrospective study was conducted of field and in-patient psychiatric assessments of 116 military personnel evacuated to the UK military psychiatric in-patient facility in Catterick Garrison. Results: Evacuees were mainly non-combatants (69%). A significant proportion were in reserve service (21%) and had a history of contact with mental health services (37%). Only 3% had a combat stress reaction. In over 85% of cases evacuation was for low mood attributed to separation from friends or family, or difficulties adjusting to the environment. Conclusions: These findings have implications especially for screening for suitability for deployment, and for understanding any longer-term mental health problems arising in veterans from Iraq

    From spin to anyon notation: The XXZ Heisenberg model as a D3D_{3} (or su(2)4su(2)_{4}) anyon chain

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    We discuss a relationship between certain one-dimensional quantum spin chains and anyon chains. In particular we show how the XXZ Heisenberg chain is realised as a D3D_{3} (alternately su(2)4su(2)_{4}) anyon model. We find the difference between the models lie primarily in choice of boundary condition.Comment: 13 page

    Collective states of interacting D(D3)D(D_3) non-Abelian anyons

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    We study the finite size spectrum of integrable quantum chains of interacting non-Abelian anyons constructed using the Drinfeld double of the dihedral group D3D_3. The gapless low energy modes are identified as the direct product of two conformal field theories which can be decomposed according to the residual symmetries of the chains subject to periodic boundary conditions.Comment: 11 page

    Induced Topological Phases at the Boundary of 3D Topological Superconductors

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    We present tight-binding models of 3D topological superconductors in class DIII that support a variety of winding numbers. We show that gapless Majorana surface states emerge at their boundary in agreement with the bulk-boundary correspondence. At the presence of a Zeeman field, the surface states become gapped and the boundary behaves as a 2D superconductor in class D. Importantly, the 2D and 3D winding numbers are in agreement, signifying that the topological phase of the boundary is induced by the phase of the 3D bulk. Hence, the boundary of a 3D topological superconductor in class DIII can be used for the robust realization of localized Majorana zero modes

    Uniqueness of reconstruction and an inversion procedure for thermoacoustic and photoacoustic tomography

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    The paper contains a simple approach to reconstruction in Thermoacoustic and Photoacoustic Tomography. The technique works for any geometry of point detectors placement and for variable sound speed satisfying a non-trapping condition. A uniqueness of reconstruction result is also obtained

    Between overt and covert research: concealment and disclosure in an ethnographic study of commercial hospitality

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    This article examines the ways in which problems of concealment emerged in an ethnographic study of a suburban bar and considers how disclosure of the research aims, the recruitment of informants, and elicitation of information was negotiated throughout the fieldwork. The case study demonstrates how the social context and the relationships with specific informants determined overtness or covertness in the research. It is argued that the existing literature on covert research and covert methods provides an inappropriate frame of reference with which to understand concealment in fieldwork. The article illustrates why concealment is sometimes necessary, and often unavoidable, and concludes that the criticisms leveled against covert methods should not stop the fieldworker from engaging in research that involves covertness

    Accommodating 'others'?: housing dispersed, forced migrants in the UK

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    Utilising insights from a qualitative study in the city of Leeds (UK), this paper considers issues related to the housing of dispersed forced migrants. The term 'dispersed forced migrants' is used here as a general label to include four groups of international migrants (i.e. refugees, asylum seekers, those with humanitarian protection status and failed asylum seekers) who have previously been dispersed, on a no choice basis, to a variety of locations across the UK under the requirements of the Immigration and Asylum Act (1999). The tiering of housing entitlement that exists within the generic population of dispersed forced migrants (a consequence of the particular socio-legal status assigned to individuals), and its role in rendering migrants susceptible to homelessness is outlined. The adequacy/standard of accommodation made available to forced migrants is also discussed. It is concluded that current arrangements fail to meet the basic housing needs of many forced migrants. Any future improvement in this situation will require a significant shift in government policy

    Adsorption of rare earth elements in regolith-hosted clay deposits

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    Global resources of heavy Rare Earth Elements (REE) are dominantly sourced from Chinese regolith-hosted ion-adsorption deposits in which the REE are inferred to be weakly adsorbed onto clay minerals. Similar deposits elsewhere might provide alternative supply for these high-tech metals, but the adsorption mechanisms remain unclear and the adsorbed state of REE to clays has never been demonstrated in situ. This study compares the mineralogy and speciation of REE in economic weathering profiles from China to prospective regoliths developed on peralkaline rocks from Madagascar. We use synchrotron X-ray absorption spectroscopy to study the distribution and local bonding environment of Y and Nd, as proxies for heavy and light REE, in the deposits. Our results show that REE are truly adsorbed as easily leachable 8- to 9-coordinated outer-sphere hydrated complexes, dominantly onto kaolinite. Hence, at the atomic level, the Malagasy clays are genuine mineralogical analogues to those currently exploited in China

    Trait analysis reveals DOG1 determines initial depth of seed dormancy, but not changes during dormancy cycling that result in seedling emergence timing.

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    Seedling emergence timing is crucial in competitive plant communities and so contributes to species fitness. To understand the mechanistic basis of variation in seedling emergence timing, we exploited the contrasting behaviour of two Arabidopsis ecotypes; Cape Verde island (Cvi) and Burren (Bur-0). We used RNAseq analysis of RNA from exhumed seeds and quantitative trait loci (QTL) analyses on a mapping population from crossing the Cvi and Bur-0 ecotypes. We determined genome-wide expression patterns over an annual dormancy cycle in both ecotypes identifying nine major clusters based on the seasonal timing of gene expression, and variation in behaviour between them. QTL were identified for depth of seed dormancy and Seedling Emergence Timing (SET). Both analyses showed a key role for DOG1 in determining depth of dormancy, but did not support a direct role for DOG1 in generating altered seasonal patterns of seedling emergence. The principle QTL determining Seedling Emergence Timing (SET1: dormancy cycling) is physically close on chromosome 5, but distinct from DOG1. We show that SET1 and two other SET QTLs each contain a candidate gene (AHG1, ANAC60, PDF1 respectively) closely associated to DOG1 and abscisic acid signalling and suggest a model for the control of SET in the field
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