1,589 research outputs found
Asymptotically optimum rank tests for contiguous location and scale alternatives : (prepublication)
Flavor-Symmetry Restoration and Symanzik Improvement for Staggered Quarks
We resolve contradictions in the literature concerning the origins and size
of unphysical flavor-changing strong interactions generated by the
staggered-quark discretization of QCD. We show that the leading contributions
are tree-level in \order(a^2) and that they can be removed by adding three
correction terms to the link operator in the standard action. These corrections
are part of the systematic Symanzik improvement of the staggered-quark action.
We present a new improved action for staggered quarks that is accurate up to
errors of \order(a^4,a^2\alpha_s) --- more accurate than most, if not all,
other discretizations of light-quark dynamics.Comment: 7 page
Scaling of the critical temperature and quark potential with a renormalization group improved SU(3) gauge action
We study the scaling property of the ratio of the critical temperature
to the square root of the string tension in the SU(3) pure gauge
theory using a renormalization group improved action. We first determine the
critical coupling on lattices with temporal extension and 6,
and then calculate the static quark potential at the critical couplings on
lattices at zero temperature. The values of in the
infinite volume limit are identical within errors, while they are slightly
larger than the value extrapolated to the continuum limit with the standard
action. We also note that the rotational invariance of the static quark
potential is remarkably restored in the both cases, and that the potential
in physical units scales in the whole region of investigated.Comment: 3 pages of Latex, 5 PostScript figures, Talk presented at
LATTICE96(finite temperature
Effects of large field cutoffs in scalar and gauge models
We discuss the notion of a large field cutoff for lattice gauge models with
compact groups. We propose and compare gauge invariant and gauge dependent (in
the Landau gauge) criteria to sort the configurations into ``large-field'' and
``small-field'' configurations. We show that the correlations between volume
average of field size indicators and the behavior of the tail of the
distribution are very different in the gauge and scalar cases. We show that the
effect of discarding the large field configurations on the plaquette average is
very different above, below and near beta=5.6 for a pure SU(3) LGT.Comment: Lattice2004(theory
One-Loop Self Energy and Renormalization of the Speed of Light for some Anisotropic Improved Quark Actions
One-loop corrections to the fermion rest mass M_1, wave function
renormalization Z_2 and speed of light renormalization C_0 are presented for
lattice actions that combine improved glue with clover or D234 quark actions
and keep the temporal and spatial lattice spacings, a_t and a_s, distinct. We
explore a range of values for the anisotropy parameter \chi = a_s/a_t and treat
both massive and massless fermions.Comment: 45 LaTeX pages with 4 postscript figure
Impact des termites dans les champs paysans de riz et de mais en savane sub-soudanienne (Booro-Borotou, Côte-d\'Ivoire)
Les termites appartiennent au groupe des arthropodes et jouent un rôle prépondérant dans les régions tropicales et sub-tropicales. L\'objectif de la présente étude est d\'évaluer les dégâts causés par les termites dans les cultures paysannes de riz (Oryza sativa L.) et de maïs (Zea mays L.). Pour se faire, un échantillonnage préliminaire a été entrepris dans le milieu naturel (savane arbustive) en vue d\'inventorier les espèces de termites présentes dans le milieu afin de les utiliser comme témoin durant cette étude. Six espèces de termites ont été recensées dans le milieu naturel contre respectivement 7 et 4 dans les champs de riz et de maïs. Les ouvriers de termites champignonnistes (Microtermes
sp, Ancistrotermes sp) et les xylophages (Amitermes sp.) ont été fréquemment rencontrés dans le système racinaire et à l\'intérieur des tiges des deux cultures et sont considérés comme responsables des dégâts. Certains termites souterrains (Microtermes sp, Ancistrotermes sp et Amitermes sp) endommagent les racines et les tiges de maïs. Ils
sont par conséquent responsables de la verse des plantes après sénescence. D\'autres termites comme Pseudacanthotermes sp et Macrotermes sp construisent des placages sur les plants qu\'ils utilisent pour les attaquer. Aucun dégât n\'a été attribué aux termites humivores Cubitermes sp .Termites belong to the athropod group and play a tremendous role in tropical and sub-tropical regions. The aim of this study was to assess the damages caused by termites to the rice (Oryza sativa L) and corn (Zea mays L.) in farmer fields. To reach this goal, a preliminary sampling was undertaken from the natural environment (shrub savannah) in a view of inventorying termites species to be used in this investigation. Six species of termites were identified in the shrub savannah and 7 and 4 while were collected in the rice and corn farms, respectively. The fungus-growing
worker termites (Microtermes sp, Ancistrotermes sp) and wood-feeders ones (Amitermes sp) were frequently met in the root system and in the stems of the two crops and they were identified as those responsible for damages. Some subterranean termites (Microtermes sp, Ancistrotermes sp and Amitermes sp) damage the roots and stems of corn.
They are subsequently responsible for the fall of crops after senescence. Other termites such as Pseudacanthotermes sp and Macrotermes sp build up outside layers on crop that they use to infest it. No soil-feeding termite (Cubitermes sp) was held responsible for any damage. Keywords: Termites, damage, peasant, rice,corn. Sciences & Nature Vol. 5 (2) 2008: pp. 121-13
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