3,634 research outputs found

    Higher Order Variational Integrators: a polynomial approach

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    We reconsider the variational derivation of symplectic partitioned Runge-Kutta schemes. Such type of variational integrators are of great importance since they integrate mechanical systems with high order accuracy while preserving the structural properties of these systems, like the symplectic form, the evolution of the momentum maps or the energy behaviour. Also they are easily applicable to optimal control problems based on mechanical systems as proposed in Ober-Bl\"obaum et al. [2011]. Following the same approach, we develop a family of variational integrators to which we refer as symplectic Galerkin schemes in contrast to symplectic partitioned Runge-Kutta. These two families of integrators are, in principle and by construction, different one from the other. Furthermore, the symplectic Galerkin family can as easily be applied in optimal control problems, for which Campos et al. [2012b] is a particular case.Comment: 12 pages, 1 table, 23rd Congress on Differential Equations and Applications, CEDYA 201

    Bridging the Location Gap: Physician Perspectives of Physician-Pharmacist Collaboration in Patient Care (BRIDGE Phase II)

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    Background: To optimize patient outcomes, the patient-centred medical home model emphasizes comprehensive team-based care. Pharmacists are qualified to enhance appropriate medication use and help improve patient outcomes through provision of medication therapy management (MTM) services. To optimally provide MTM, pharmacists must effectively collaborate with physicians. This study explored factors that influence pharmacist-physician collaboration. Methods and Findings: A convenience sample of five physicians participated in semi-structured interviews and the resulting data were analyzed using qualitative methods. Transcripts of the interviews were independently coded for themes by two researchers. Five themes emerged: trustworthiness, role specification, relationship initiation, effects on practice, and professional awareness/expectations. Conclusions: Overall interviewees spoke positively about pharmacists; however, when discussing collaboration, they spoke almost exclusively about pharmacists within their clinic. Since most pharmacists practice outside of clinics, bridging the location gap is imperative for collaboration. In addition, physicians lacked an overall understanding of pharmacists’ training and clinical capacity. This may inhibit pharmacists from participating to their full professional capability within integrated healthcare teams. One approach to resolve this lack of physician understanding of pharmacists’ role and value may be to co-educate health professional students. Further research is needed to explore ways to improve interprofessional collaborative care

    Electrochemical synthesis, characterisation, and preliminary biological evaluation of an anodic aluminium oxide membrane with a pore size of 100 nanometres for a Potential Cell Culture Substrate

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    In this study we investigate the electrochemical synthesis and characterisation of a nanometre scale porous anodic aluminium oxide (AAO) membranes with a mean pore diameter of 100 nm. The membranes exhibit interesting properties such as controllable pore diameters, periodicity and density distribution. These properties can be preselected by adjusting the controlling parameters of a temperature controlled two-step anodization process. The surface features of the nanometre scale membrane such as pore density, pore diameter and inter-pore distance were quantified using field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM). A preliminary biological evaluation of the membranes was carried out to determine cell adhesion and morphology using the Cercopithecus aethiops[African green monkey – (Vero)] kidney epithelial cell line. Optical microscopy, FESEM and AFM investigations revealed the presence of focal adhesion sites over the surface of the porous membranes. The positive outcomes of the study, indicates that AAO membranes can be used as a viable tissue scaffold for potential tissue engineering applications in the future

    Metastable anions of dinitrobenzene: resonances for electron attachment and kinetic energy release

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    Attachment of free, low-energy electrons to dinitrobenzene (DNB) in the gas phase leads to DNB as well as several fragment anions. DNB, (DNB-H), (DNB-NO), (DNB-2NO), and (DNB-NO(2)) are found to undergo metastable (unimolecular) dissociation. A rich pattern of resonances in the yield of these metastable reactions versus electron energy is observed; some resonances are highly isomer-specific. Most metastable reactions are accompanied by large average kinetic energy releases (KER) that range from 0.5 to 1.32 eV, typical of complex rearrangement reactions, but (1,3-DNB-H)(-) features a resonance with a KER of only 0.06 eV for loss of NO. (1,3-DNB-NO)(-) offers a rare example of a sequential metastable reaction, namely, loss of NO followed by loss of CO to yield C(5)H(4)O(-) with a large KER of 1.32 eV. The G4(MP2) method is applied to compute adiabatic electron affinities and reaction energies for several of the observed metastable channels. (C) 2010 American Institute of Physics. [doi:10.1063/1.3514931

    Probabilistic Weyl laws for quantized tori

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    For the Toeplitz quantization of complex-valued functions on a 2n2n-dimensional torus we prove that the expected number of eigenvalues of small random perturbations of a quantized observable satisfies a natural Weyl law. In numerical experiments the same Weyl law also holds for ``false'' eigenvalues created by pseudospectral effects.Comment: 33 pages, 3 figures, v2 corrected listed titl

    Relaxation of Surface Profiles by Evaporation Dynamics

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    We present simulations of the relaxation towards equilibrium of one dimensional steps and sinusoidal grooves imprinted on a surface below its roughening transition. We use a generalization of the hypercube stacking model of Forrest and Tang, that allows for temperature dependent next-nearest-neighbor interactions. For the step geometry the results at T=0 agree well with the t^(1/4) prediction of continuum theory for the spreading of the step. In the case of periodic profiles we modify the mobility for the tips of the profile and find the approximate solution of the resulting free boundary problem to be in reasonable agreement with the T=0 simulations.Comment: 6 pages, Revtex, 5 Postscript figures, to appear in PRB 15, October 199

    Carrier-density effects in many-polaron systems

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    Many-polaron systems with finite charge-carrier density are often encountered experimentally. However, until recently, no satisfactory theoretical description of these systems was available even in the framework of simple models such as the one-dimensional spinless Holstein model considered here. In this work, previous results obtained using numerical as well as analytical approaches are reviewed from a unified perspective, focussing on spectral properties which reveal the nature of the quasiparticles in the system. In the adiabatic regime and for intermediate electron-phonon coupling, a carrier-density driven crossover from a polaronic to a rather metallic system takes place. Further insight into the effects due to changes in density is gained by calculating the phonon spectral function, and the fermion-fermion and fermion-lattice correlation functions. Finally, we provide strong evidence against the possibility of phase separation.Comment: 13 pages, 6 figures, accepted for publication in J. Phys.: Condens. Matter; final versio

    Flow properties of driven-diffusive lattice gases: theory and computer simulation

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    We develop n-cluster mean-field theories (0 < n < 5) for calculating the flow properties of the non-equilibrium steady-states of the Katz-Lebowitz-Spohn model of the driven diffusive lattice gas, with attractive and repulsive inter-particle interactions, in both one and two dimensions for arbitrary particle densities, temperature as well as the driving field. We compare our theoretical results with the corresponding numerical data we have obtained from the computer simulations to demonstrate the level of accuracy of our theoretical predictions. We also compare our results with those for some other prototype models, notably particle-hopping models of vehicular traffic, to demonstrate the novel qualitative features we have observed in the Katz-Lebowitz-Spohn model, emphasizing, in particular, the consequences of repulsive inter-particle interactions.Comment: 12 RevTex page
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