525 research outputs found
How well do lattice simulations reproduce the different aspects of the geometric Schwinger model
We compare continuum and lattice formulation of the geometric Schwinger Model
on the torus. The lattice reproduces the anomaly, related to
non-trivial topological gauge configurations and zero modes.Comment: 3 pages, DESY 93-144, talk presented by H. Dilger at Lattice 9
Topological Zero Modes in Monte Carlo Simulations
We present an improvement of global Metropolis updating steps, the instanton
hits, used in a hybrid Monte Carlo simulation of the two-flavor Schwinger model
with staggered fermions. These hits are designed to change the topological
sector of the gauge field. In order to match these hits to an unquenched
simulation with pseudofermions, the approximate zero mode structure of the
lattice Dirac operator has to be considered explicitly.Comment: uuencoded compressed tar file, latex, 11 pages, 4 figures, DESY
94-14
Topological transitions in the euclidean 2d U(1)-Higgs model
The two-dimensional U(1)-gauged Higgs model is studied on an euclidean
lattice of size , where the temperature is of the
order of the sphaleron mass. The simulation parameters are taken from zero
temperature results. By comparison with classical and semiclassical results I
discuss, whether the sphaleron transition rate can be extracted from the
behavior of the Chern-Simons number and from the formation of vortices in an
euclidean simulation at high temperatures.Comment: Talk presented at LATTICE96(topology), 3 pages, latex2e, 3 postscript
figures, uses packages epsfig and espcrc
Population studies on Phytophthora infestans on potatoes and tomatoes in southern Germany
Fifty-seven isolates of Phytophthora infestans from blighted potato foliage were collected in 1995 in southern Germany and analysed for mating type and sensitivity to metalaxyl. Fifty-six of them were characterised as A1 and one as A2 mating types. Resistance to metalaxyl was observed frequently: 53 isolates were resistant, three were partially sensitive, and one was sensitive. In a subsequent field study in 1999, 84 isolates collected from blighted potato and tomato foliage were analysed for mating type. Seventy-two were characterised as A1 and twelve as A2 mating types. The response of 76 isolates to metalaxyl and to propamocarb was tested. The majority (42) of the 76 isolates was classified as resistant to metalaxyl; 31 were partially sensitive and only three isolates were sensitive. The results with propamocarb were less discrete; 10 isolates were classified as resistant and three were clearly sensitive. AFLP fingerprinting was used to examine the genetic structure of the southern German P. infestans population collected in 1999 and indicated that the tested population can be sub-divided into a tomato group, a potato group and a mixed group containing isolates collected from both crops. The presence of Ia and IIa mitochondrial DNA haplotypes indicates that the German P. infestans isolates belong to the new pathogen population that has also been reported in neighbouring regions of Europe. The present study indicates that at the beginning of the season only a few genotypes were present, and the population became genetically more variable at the end of the growing season
The perfect action for non-degenerate staggered fermions
The perfect action of free staggered fermions is calculated by blocking from
the continuum for degenerate and non-degenerate flavor masses. The symmetry
structure, connecting flavor transformations and translations, is explained
directly from the blocking scheme. It is convenient to use a modified Fourier
transformation, respecting this connection, to treat the spin-flavor structure
of the blockspins. The perfect action remains local in the non-degenerate case;
it is explicitly calculated in two dimensions. I finally comment on the
relation of the blocking scheme to the transition from Dirac-K\"ahler fermions
to staggered fermions.Comment: 14 pages, Latex2e, 1 Latex figure, some minor changes and two
references adde
Auflösung von Strahlenschutzbereichen und Freigabe von Materialien im Forschungszentrum Karlsruhe
Vorschlag fuer Aenderungen der Richtlinie \u27Berechnungsgrundlage fuer die Ermittlung der Koerperdosis bei innerer Strahlenexposition\u27
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