6,394 research outputs found
HMC algorithm with multiple time scale integration and mass preconditioning
We describe a new HMC algorithm variant we have recently introduced and
extend the published results by preliminary results of a simulation with a
pseudo scalar mass value of about 300 MeV. This new run confirms our
expectation that simulations with such pseudo scalar mass values become
feasible and affordable with our HMC variant. In addition we discuss
simulations from hot and cold starts at a pseudo scalar mass value of about 300
MeV, which we performed in order to test for possible meta-stabilities.Comment: 6 pages, Talk presented at Lattice 2005 (machines and algorithms
Structural and Magnetic Properties of Trigonal Iron
First principles calculations of the electronic structure of trigonal iron
were performed using density function theory. The results are used to predict
lattice spacings, magnetic moments and elastic properties; these are in good
agreement with experiment for both the bcc and fcc structures. We find however,
that in extracting these quantities great care must be taken in interpreting
numerical fits to the calculated total energies. In addition, the results for
bulk iron give insight into the properties of thin iron films. Thin films grown
on substrates with mismatched lattice constants often have non-cubic symmetry.
If they are thicker than a few monolayers their electronic structure is similar
to a bulk material with an appropriately distorted geometry, as in our trigonal
calculations. We recast our bulk results in terms of an iron film grown on the
(111) surface of an fcc substrate, and find the predicted strain energies and
moments accurately reflect the trends for iron growth on a variety of
substrates.Comment: 11 pages, RevTeX,4 tar'd,compressed, uuencoded Postscript figure
Non-perturbative renormalization of the axial current with improved Wilson quarks
We present a new normalization condition for the axial current, which is
derived from the PCAC relation with non-vanishing mass.
Using this condition reduces the O(r_0 m) corrections to the axial current
normalization constant Z_A for an easier chiral extrapolation in the cases,
where simulations at zero quark-mass are not possible. The method described
here also serves as a preparation for a determination of Z_A in the full
two-flavor theory.Comment: 3 pages, 3 figures, Lattice2003(improve
Züchterische Bearbeitung von Süßlupinen für den ökologischen Landbau - Variabilität wichtiger Inhaltsstoffe in Abhängigkeit vom Standort -
Lupines are used as protein-rich feeding stuff with high quality for the organic farming. Therefore important quality parameters are estimated in different cultivars and breed-ing lines of blue lupins in relation to location. Protein content, amino acid composition, fat and fatty acid composition, as well as antinutritive substances (raffinose oligosac-charides and alkaloids) were often more different between locations than cultivars. The reason for differences in content and composition of the ingredients is caused probably by diverse environmental conditions especially soil acidity (pH-value)
Using concept mapping to design an indicator framework for addiction treatment centers.
Objective. The objective of this study is to determine an indicator framework for addiction treatment centres based on the demands of stakeholders and in alignment with the European Foundation for Quality Management (EFQM) Excellence Model. Setting. The setting is the Jellinek Centre based in Amsterdam, the Netherlands, which serves as a prototype for an addiction treatment centre. Method. Concept mapping was used in the construction of the indicator framework. During the 1-day workshop, 16 stake-holders generated, prioritized and sorted 73 items concerning quality and performance. Multidimensional scaling and cluster analysis was applied in constructing a framework consisting of two dimensions and eight clusters. Results. The horizontal axis of the indicator framework is named 'Organization' and has two poles, namely, 'Processes' and 'Results'. The vertical axis is named 'Task' and the poles are named 'Efficient treatment' and 'Prevention programs'. The eight clusters in the two-dimensional framework are arranged in the following, prioritized sequence: 'Efficient treatment network', 'Effective service', 'Target group', 'Quality of life', 'Efficient service', 'Knowledge transfer', 'Reducing addiction related problems', and 'Prevention programs'. The most important items in the framework are: 'patients are satisfied with their treatment', 'early interventions', and 'efficient treatment chain'. Conclusion. The indicator framework aligns with three clusters of the results criteria of the EFQM Excellence Model. It is based on the stakeholders' perspectives and is believed to be specific for addiction treatment centres. The study demonstrates that concept mapping is a suitable strategy for generating indicator frameworks. © The Author 2005. Published by Oxford University Press on behalf of International Society for Quality in Health Care; all rights reserved
Comparison between overlap and twisted mass fermions towards the chiral limit
We compare overlap fermions, which are chirally invariant, and Wilson twisted
mass fermions in the approach to the chiral limit. Our quenched simulations
reveal that with both formulations of lattice fermions pion masses of O(250
MeV) can be reached in practical simulations. Our comparison is done at a fixed
lattice spacing a=0.123 fm. Several quantities are measured, such as hadron
masses and pseudoscalar decay constants.Comment: Lattice2004(chiral
Structure prediction based on ab initio simulated annealing for boron nitride
Possible crystalline modifications of chemical compounds at low temperatures
correspond to local minima of the energy landscape. Determining these minima
via simulated annealing is one method for the prediction of crystal structures,
where the number of atoms per unit cell is the only information used. It is
demonstrated that this method can be applied to covalent systems, at the
example of boron nitride, using ab initio energies in all stages of the
optimization, i.e. both during the global search and the subsequent local
optimization. Ten low lying structure candidates are presented, including both
layered structures and 3d-network structures such as the wurtzite and zinc
blende types, as well as a structure corresponding to the beta-BeO type
Lattice Spacing Dependence of the First Order Phase Transition for Dynamical Twisted Mass Fermions
Lattice QCD with Wilson fermions generically shows the phenomenon of a first
order phase transition. We study the phase structure of lattice QCD using
Wilson twisted mass fermions and the Wilson plaquette gauge action are used in
a range of beta values where such a first order phase transition is observed.
In particular, we investigate the dependence of the first order phase
transition on the value of the lattice spacing. Using only data in one phase
and neglecting possible problems arising from the phase transition we are able
to perform a first scaling test for physical quantities using this action.Comment: 15 pages, 7 figures, typo corrected, web-list of authors correcte
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