810 research outputs found

    Growth of fat slits and dispersionless KP hierarchy

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    A "fat slit" is a compact domain in the upper half plane bounded by a curve with endpoints on the real axis and a segment of the real axis between them. We consider conformal maps of the upper half plane to the exterior of a fat slit parameterized by harmonic moments of the latter and show that they obey an infinite set of Lax equations for the dispersionless KP hierarchy. Deformation of a fat slit under changing a particular harmonic moment can be treated as a growth process similar to the Laplacian growth of domains in the whole plane. This construction extends the well known link between solutions to the dispersionless KP hierarchy and conformal maps of slit domains in the upper half plane and provides a new, large family of solutions.Comment: 26 pages, 6 figures, typos correcte

    Full density matrix dynamics for large quantum systems: Interactions, Decoherence and Inelastic effects

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    We develop analytical tools and numerical methods for time evolving the total density matrix of the finite-size Anderson model. The model is composed of two finite metal grains, each prepared in canonical states of differing chemical potential and connected through a single electronic level (quantum dot or impurity). Coulomb interactions are either excluded all together, or allowed on the dot only. We extend this basic model to emulate decoherring and inelastic scattering processes for the dot electrons with the probe technique. Three methods, originally developed to treat impurity dynamics, are augmented to yield global system dynamics: the quantum Langevin equation method, the well known fermionic trace formula, and an iterative path integral approach. The latter accommodates interactions on the dot in a numerically exact fashion. We apply the developed techniques to two open topics in nonequilibrium many-body physics: (i) We explore the role of many-body electron-electron repulsion effects on the dynamics of the system. Results, obtained using exact path integral simulations, are compared to mean-field quantum Langevin equation predictions. (ii) We analyze aspects of quantum equilibration and thermalization in large quantum systems using the probe technique, mimicking elastic-dephasing effects and inelastic interactions on the dot. Here, unitary simulations based on the fermionic trace formula are accompanied by quantum Langevin equation calculations

    Numerical and experimental study of agglomerate dispersion in polymer extrusion

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    A model for agglomerate dispersion in screw extruders was developed and superimposed on the flow patterns as simulated using the FIDAP software. A particle tracking algorithm with an adaptive time step was used to follow the agglomerates trajectory. Along this flow path, the breakup probability was estimated using a Monte Carlo method and in conjunction with the local fragmentation number. Particle size distributions and Shannon entropy were computed along the screw channel. The results show good qualitative agreement between model predictions and experimental data

    Hydrodynamic reductions of the heavenly equation

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    We demonstrate that Pleba\'nski's first heavenly equation decouples in infinitely many ways into a triple of commuting (1+1)-dimensional systems of hydrodynamic type which satisfy the Egorov property. Solving these systems by the generalized hodograph method, one can construct exact solutions of the heavenly equation parametrized by arbitrary functions of a single variable. We discuss explicit examples of hydrodynamic reductions associated with the equations of one-dimensional nonlinear elasticity, linearly degenerate systems and the equations of associativity.Comment: 14 page

    Dexamethasone and oxygen therapy in care home residents with diabetes: a management guide and algorithm for treatment: a rapid response action statement from the European Diabetes Working Party for Older People (EDWPOP) and European Geriatric Medicine Society (EuGMS)

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    This statement addresses the need to provide clinically relevant and practical guidance for long-term care staff working in care homes and other stakeholders engaged in the care of residents who require consideration for dexamethasone and oxygen therapy. It had been provided following a series of consensus discussions between the EDWPOP and the EuGMS in January and February 2021. Its main aim is to minimise morbidity and mortality from serious acute illnesses including COVID-19 requiring these treatments within the long-term care sector. © 2021, The Author(s)

    Hydrodynamics of cold atomic gases in the limit of weak nonlinearity, dispersion and dissipation

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    Dynamics of interacting cold atomic gases have recently become a focus of both experimental and theoretical studies. Often cold atom systems show hydrodynamic behavior and support the propagation of nonlinear dispersive waves. Although this propagation depends on many details of the system, a great insight can be obtained in the rather universal limit of weak nonlinearity, dispersion and dissipation (WNDD). In this limit, using a reductive perturbation method we map some of the hydrodynamic models relevant to cold atoms to well known chiral one-dimensional equations such as KdV, Burgers, KdV-Burgers, and Benjamin-Ono equations. These equations have been thoroughly studied in literature. The mapping gives us a simple way to make estimates for original hydrodynamic equations and to study the interplay between nonlinearity, dissipation and dispersion which are the hallmarks of nonlinear hydrodynamics.Comment: 18 pages, 3 figures, 1 tabl

    Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam

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    The SciBooNE Collaboration reports a measurement of inclusive charged current interactions of muon neutrinos on carbon with an average energy of 0.8 GeV using the Fermilab Booster Neutrino Beam. We compare our measurement with two neutrino interaction simulations: NEUT and NUANCE. The charged current interaction rates (product of flux and cross section) are extracted by fitting the muon kinematics, with a precision of 6-15% for the energy dependent and 3% for the energy integrated analyses. We also extract CC inclusive interaction cross sections from the observed rates, with a precision of 10-30% for the energy dependent and 8% for the energy integrated analyses. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. These results can be used to convert previous SciBooNE cross section ratio measurements to absolute cross section values.Comment: 21 pages, 16 figures. Accepted by Phys. Rev. D. Minor revisions to match the accepted versio

    Essential steps in primary care management of older people with Type 2 diabetes: an executive summary on behalf of the European geriatric medicine society (EuGMS) and the European diabetes working party for older people (EDWPOP) collaboration

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    We present an executive summary of a guideline for management of type 2 diabetes mellitus in primary care written by the European Geriatric Medicine Society, the European Diabetes Working Party for Older People with contributions from primary care practitioners and participation of a patient’s advocate. This consensus document relies where possible on evidence-based recommendations and expert opinions in the fields where evidences are lacking. The full text includes 4 parts: a general strategy based on comprehensive assessment to enhance quality and individualised care plan, treatments decision guidance, management of complications, and care in case of special conditions. Screening for frailty and cognitive impairment is recommended as well as a comprehensive assessment all health conditions are concerned, including end of life situations. The full text is available online at the following address: essential_steps_inprimary_care_in_older_people_with_diabetes_-_EuGMS-EDWPOP___3_.pdf

    Search for Charged Current Coherent Pion Production on Carbon in a Few-GeV Neutrino Beam

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    The SciBooNE Collaboration has performed a search for charged current coherent pion production from muon neutrinos scattering on carbon, \nu_\mu ^{12}C \to \mu^- ^{12}C \pi^+, with two distinct data samples. No evidence for coherent pion production is observed. We set 90% confidence level upper limits on the cross section ratio of charged current coherent pion production to the total charged current cross section at 0.67\times 10^{-2} at mean neutrino energy 1.1 GeV and 1.36\times 10^{-2} at mean neutrino energy 2.2 GeV.Comment: 18 pages, 16 figures, Minor revisions to match version accepted for publication in Physical Review

    Amino acid profiles in older adults with frailty. Secondary analysis from MetaboFrail and BIOSPHERE studies

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    An altered amino acid metabolism has been described in frail older adults which may contribute to muscle loss and functional decline associated with frailty. In the present investigation, we compared circulating amino acid profiles of older adults with physical frailty and sarcopenia (PF&S, n = 94), frail/pre-frail older adults with type 2 diabetes mellitus (F-T2DM, n = 66), and robust non-diabetic controls (n = 40). Partial least squares discriminant analysis (PLS–DA) models were built to define the amino acid signatures associated with the different frailty phenotypes. PLS–DA allowed correct classification of participants with 78.2 ± 1.9% accuracy. Older adults with F-T2DM showed an amino acid profile characterized by higher levels of 3-methylhistidine, alanine, arginine, ethanolamine, and glutamic acid. PF&S and control participants were discriminated based on serum concentrations of aminoadipic acid, aspartate, citrulline, cystine, taurine, and tryptophan. These findings suggest that different types of frailty may be characterized by distinct metabolic perturbations. Amino acid profiling may therefore serve as a valuable tool for frailty biomarker discovery
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