6,292 research outputs found

    Exactly solvable quantum spin tubes and ladders

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    We find families of integrable n-leg spin-1/2 ladders and tubes with general isotropic exchange interactions between spins. These models are equivalent to su(N) spin chains with N=2^n. Arbitrary rung interactions in the spin tubes and ladders induce chemical potentials in the equivalent spin chains. The potentials are n-dependent and differ for the tube and ladder models. The models are solvable by means of nested Bethe Ansatz.Comment: 6 pages, Latex, 1 eps fig, to appear in J. Phys.

    21st century social work: reducing re-offending - key practice skills

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    This literature review was commissioned by the Scottish Executive’s Social Work Services Inspectorate in order to support the work of the 21st Century Social Work Review Group. Discussions in relation to the future arrangements for criminal justice social work raised issues about which disciplines might best encompass the requisite skills for reducing re-offending in the community. Rather than starting with what is known or understood about the skills of those professionals currently involved in such interventions, this study sought to start with the research evidence on effective work with offenders to reduce re-offending and then work its way back to the skills required to promote this outcome

    Lattice Boltzmann simulations of a viscoelastic shear-thinning fluid

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    We present a hybrid lattice Boltzmann algorithm for the simulation of flow glass-forming fluids, characterized by slow structural relaxation, at the level of the Navier-Stokes equation. The fluid is described in terms of a nonlinear integral constitutive equation, relating the stress tensor locally to the history of flow. As an application, we present results for an integral nonlinear Maxwell model that combines the effects of (linear) viscoelasticity and (nonlinear) shear thinning. We discuss the transient dynamics of velocities, shear stresses, and normal stress differences in planar pressure-driven channel flow, after switching on (startup) and off (cessation) of the driving pressure. This transient dynamics depends nontrivially on the channel width due to an interplay between hydrodynamic momentum diffusion and slow structural relaxation

    Magnetic Susceptibility of an integrable anisotropic spin ladder system

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    We investigate the thermodynamics of a spin ladder model which possesses a free parameter besides the rung and leg couplings. The model is exactly solved by the Bethe Ansatz and exhibits a phase transition between a gapped and a gapless spin excitation spectrum. The magnetic susceptibility is obtained numerically and its dependence on the anisotropy parameter is determined. A connection with the compounds KCuCl3, Cu2(C5H12N2)2Cl4 and (C5H12N)2CuBr4 in the strong coupling regime is made and our results for the magnetic susceptibility fit the experimental data remarkably well.Comment: 12 pages, 12 figures included, submitted to Phys. Rev.

    Watershed development: A solution to water shortages in semi-arid India or part of the problem?

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    There have been dramatic changes in the hydrology of many of the dry areas of South India in recent years as a result of increased groundwater-based irrigation, watershed development and land use change. Although intensive development of water resources has brought about huge benefits, its very success has thrown up new challenges. Demand and competition for water has increased to the extent that — in some areas — current levels of annual water use are so high that, in all but the wettest years, annual water use approximates towards annual replenishment of surface and ground water resources. In these areas, it is clear that the emphasis should switch from development to the management of water resources to ensure that water is allocated to activities with the highest economic and social value. Although current watershed development programmes bring a range of benefits, they may also change the temporal and spatial pattern of water availability and use. This can result in significant negative trade-offs such as more unreliable domestic water supplies in ‘downstream’ areas, particularly during low rainfall or drought years. As part of the Karnataka Watershed Development Project (KAWAD), a water resource audit assessed the status of water resources in the project watersheds and identified resource management practices that should be promoted by the project. This paper summarises the audit’s findings and recommendations, the main lessons learned and progress to date in implementing recommendations. For comparison, findings and recommendations from a water audit in southern Andhra Pradesh are also summarised.Resource /Energy Economics and Policy,

    Exactly solvable quantum spin ladders associated with the orthogonal and symplectic Lie algebras

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    We extend the results of spin ladder models associated with the Lie algebras su(2n)su(2^n) to the case of the orthogonal and symplectic algebras $o(2^n),\ sp(2^n)$ where n is the number of legs for the system. Two classes of models are found whose symmetry, either orthogonal or symplectic, has an explicit n dependence. Integrability of these models is shown for an arbitrary coupling of XX type rung interactions and applied magnetic field term.Comment: 7 pages, Late

    Phase diagram of an exactly solvable t-J ladder model

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    We study a system of one-dimensional t-J models coupled to a ladder system. A special choice of the interaction between neighbouring rungs leads to an integrable model with supersymmetry, which is broken by the presence of rung interactions. We analyze the spectrum of low-lying excitations and ground state phase diagram at zero temperature.Comment: LaTeX, 8 pp. incl. 1 figur

    Surface width scaling in noise reduced Eden clusters

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    The surface width scaling of Eden A clusters grown from a single aggregate site on the square lattice is investigated as a function of the noise reduction parameter. A two-exponent scaling ansatz is introduced and used to fit the results from simulations covering the range from fully stochastic to the zero-noise limit.Comment: 4 pages, RevTex, 3 figure

    European Paediatric Formulation Initiative (EuPFI)-Formulating Ideas for Better Medicines for Children.

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    © American Association of Pharmaceutical Scientists 2016, published by Springer US, available online at doi: https://doi.org/10.1208/s12249-016-0584-1The European Paediatric Formulation Initiative (EuPFI), founded in 2007, aims to promote and facilitate the preparation of better and safe medicines for children through linking research and information dissemination. It brings together the capabilities of the industry, academics, hospitals, and regulators within a common platform in order to scope the solid understanding of the major issues, which will underpin the progress towards the future of paediatric medicines we want.The EuPFI was formed in parallel to the adoption of regulations within the EU and USA and has served as a community that drives research and dissemination through publications and the organisation of annual conferences. The membership and reach of this group have grown since its inception in 2007 and continue to develop and evolve to meet the continuing needs and ambitions of research into and development of age appropriate medicines. Five diverse workstreams (age-appropriate medicines, Biopharmaceutics, Administration Devices, Excipients and Taste Assessment & Taste Masking (TATM)) direct specific workpackages on behalf of the EuPFI. Furthermore, EuPFI interacts with multiple diverse professional groups across the globe to ensure efficient working in the area of paediatric medicines. Strong commitment and active involvement of all EuPFI stakeholders have proved to be vital to effectively address knowledge gaps related to paediatric medicines, discuss potential areas for further research and identify issues that need more attention and analysis in the future.Peer reviewedFinal Accepted Versio
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