5,663 research outputs found

    Comment on: "Estimating the Hartree-Fock limit from finite basis set calculations" [Jensen F (2005) Theor Chem Acc 113:267]

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    We demonstrate that a minor modification of the extrapolation proposed by Jensen [(2005): Theor Chem Acc 113:267] yields very reliable estimates of the Hartree-Fock limit in conjunction with correlation consistent basis sets. Specifically, a two-point extrapolation of the form EHF,L=EHF,∞+A(L+1)exp⁡(−9L)E_{HF,L}=E_{HF,\infty}+A(L+1)\exp(-9\sqrt{L}) yields HF limits EHF,∞E_{HF,\infty} with an RMS error of 0.1 millihartree using aug-cc-pVQZ and aug-cc-pV5Z basis sets, and of 0.01 millihartree using aug-cc-pV5Z and aug-cc-pV6Z basis sets.Comment: Theoretical Chemistry Accounts, in pres

    A discrete solvent reaction field model for calculating frequency-dependent hyperpolarizabilities of molecules in solution

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    We present a discrete solvent reaction field (DRF) model for the calculation of frequency-dependent hyperpolarizabilities of molecules in solution. In this model the solute is described using density functional theory (DFT) and the discrete solvent molecules are described with a classical polarizable model. The first hyperpolarizability is obtained in an efficient way using time-dependent DFT and the (2n+1) rule. The method was tested for liquid water using a model in which a water molecule is embedded in a cluster of 127 classical water molecules. The frequency-dependent first and second hyperpolarizabilities related to the electric field induced second harmonic generation (EFISH) experiment, were calculated both in the gas phase and in the liquid phase. For water in the gas phase, results are obtained in good agreement with correlated wave function methods and experiments by using the so-called shape-corrected exchange correlation (xc)-potentials. In the liquid phase the effect of using asymptotically correct functionals is discussed. The model reproduced the experimentally observed sign change in the first hyperpolarizaibility when going from the gas phase to the liquid phase. Furthermore, it is shown that the first hyperpolarizability is more sensitive to damping of the solvent-solute interactions at short range than the second hyperpolarizability. (C) 2003 American Institute of Physics

    Color singlet suppression of quark-gluon plasma formation

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    The rate of quark-gluon plasma droplet nucleation in superheated hadronic matter is calculated within the MIT bag model. The requirements of color singletness and (to less extent) fixed momentum suppress the nucleation rate by many orders of magnitude, making thermal nucleation of quark-gluon plasma droplets unlikely in ultrarelativistic heavy-ion collisions if the transition is first order and reasonably described by the bag model.Comment: 9 pages, 3 ps figures. To appear in PhysRevC (April 1996

    En omstridt Grundtvig-salme og dens forstadier

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    Thorkild Borup Jensen, “A Much-Debated Grundtvig Hymn and its Preliminary Stages”In the first part of this study it is shown, by means of an analysis of structure, style, and content, that the hymn »O Christelighed« (Oh Christianity) ( 1853) meets the demands that Grundtvig himself made on the genre from the mid 1820’s onwards: The hymn should “express the living feeling that we have already passed from death to life, have found eternal life in the love of God, and have drunk of the chalice of his blessedness”. The hymn “O Christelighed” is partly a visionary image of the absolute, complete, and unqualified state of blessedness (st. 1- 3 ), partly a richly symbolic account of its causes, both those originating in human nature (Tro og Haab (faith and hope) st. 4- 5 ), and those originating in divine nature (KiĂŠrlighed (charity), st. 6- 7 ). The entire hymn is pervaded by a sense of ecstatic enthusiasm inspired by the experience of the Promised Land of Christianity here and now, and also by the certainty that the experience will continue unbroken.In the last part of the study the two earlier versions of the hymn are taken into account as well, viz. “Jeg kjender et Land” (I know a land) ( 1824) and “O dejlige Land” (Oh blessed land) ( 1832). From the three variants it is shown how Grundtvig as an artist was perpetually inspired by the baroque hymn writer Kingo—and how as a Christian preacher he dissociates himself from Kingo with increasing consistency: Conceptually, and artistically, the version of 1824 comes closest to Kingo’s hymn “Far, Verden, far vel” (a farewell to the world); in the version of 1832 there are still many Kingo reminiscences, but in the version of 1853 these are totally eradicated

    Nutrition, environment and cardiovascular health (NESCAV): protocol of an inter-regional cross-sectional study.

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    peer reviewedBACKGROUND: Despite the remarkable technological progress in health care and treatment, cardiovascular disease remains the leading cause of premature death, prolonged hospitalization and disability in most European countries. In the population of the Greater Region (Grand-Duchy of Luxembourg, Wallonia in Belgium, and Lorraine in France), the prevalence of cardiovascular risk factors and disease is among the highest in Europe, warranting the need for a better understanding of factors contributing to this pattern. In this context, the cross-border "Nutrition, Environment and Cardiovascular Health-NESCAV" project is initiated by an inter-regional multi-disciplinary consortium and supported by the INTERREG IV A program "Greater Region", 2007-2013, to fight synergically and harmoniously against this major public health problem. METHODS/DESIGN: The objectives of the three-year planned project are to assess, in a representative sample of 3000 randomly selected individuals living at the Greater Region, 1) the cardiovascular health and risk profile, 2) the association between the dietary habits and the cardiovascular risk, 3) the association of occupational and environmental pollution markers with the cardiovascular risk, 4) the knowledge, awareness and level of control of cardiovascular risk factors, 5) the potential gaps in the current primary prevention, and finally, to address evidence-based recommendations enabling the development of inter-regional guidance to help policy-makers and health care workers for the prevention of cardiovascular disease. DISCUSSION: The findings will provide tools that may enable the Greater Region's decision-makers and health professionals to implement targeted and cost-effective prevention strategies

    Effective temperature in driven vortex lattices with random pinning

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    We study numerically correlation and response functions in non-equilibrium driven vortex lattices with random pinning. From a generalized fluctuation-dissipation relation we calculate an effective transverse temperature in the fluid moving phase. We find that the effective temperature decreases with increasing driving force and becomes equal to the equilibrium melting temperature when the dynamic transverse freezing occurs. We also discuss how the effective temperature can be measured experimentally from a generalized Kubo formula.Comment: 4 pages, 4 figure

    Maxillary Sinus Augmentation With Recombinant Human Bone Morphogenetic ProteinĂą 2 and Particulate Allograft Without an Absorbable Sponge: A Case Report

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141930/1/cap0175.pd

    Medium perturbations on the molecular polarizability calculated within a localized dipole interaction model

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    We have studied the medium effects on the frequency-dependent polarizability of water by separating the total polarizability of water clusters into polarizabilities of the individual water molecules. A classical frequency-dependent dipole–dipole interaction model based on classical electrostatics and an Unsöld dispersion formula has been used. It is shown that the model reproduces the polarizabilities of small water clusters calculated with time-dependent density functional theory. A comparison between supermolecular calculations and the localized interaction model illustrate the problems arising from using supermolecular calculations to predict the medium perturbations on the solute polarizability. It is also noted that the solute polarizability is more dependent on the local geometry of the cluster than on the size of the cluster

    Microscopic and macroscopic polarization within a combined quantum mechanics and molecular mechanics model

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    A polarizable quantum mechanics and molecular mechanics model has been extended to account for the difference between the macroscopic electric field and the actual electric field felt by the solute molecule. This enables the calculation of effective microscopic properties which can be related to macroscopic susceptibilities directly comparable with experimental results. By seperating the discrete local field into two distinct contribution we define two different microscopic properties, the so-called solute and effective properties. The solute properties account for the pure solvent effects, i.e.. effects even when the macroscopic electric field is zero, and the effective properties account for both the pure solvent effects and the effect from the induced dipoles in the solvent due to the macroscopic electric field. We present results for the linear and nonlinear polarizabilities of water and acetonitrile both in the gas phase and in the liquid phase. For all the properties we find that the pure solvent effect increases the properties whereas the induced electric field decreases the properties. Furthermore, we present results for the refractive index, third-harmonic generation (THG), and electric field induced second-harmonic generation (EFISH) for liquid water and acetonitrile. We find in general good agreement between the calculated and experimental results for the refractive index and the THG susceptibility. For the EFISH susceptibility, however, the difference between experiment and theory is larger since the orientational effect arising from the static electric field is not accurately described. (C) 2005 American Institute of Physics
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