977 research outputs found
Z-graded differential geometry of quantum plane
In this work, the Z-graded differential geometry of the quantum plane is
constructed. The corresponding quantum Lie algebra and its Hopf algebra
structure are obtained. The dual algebra, i.e. universal enveloping algebra of
the quantum plane is explicitly constructed and an isomorphism between the
quantum Lie algebra and the dual algebra is given.Comment: 17 page
A square root of the harmonic oscillator
Allowing for the inclusion of the parity operator, it is possible to
construct an oscillator model whose Hamiltonian admits an EXACT square root,
which is different from the conventional approach based on creation and
annihilation operators. We outline such a model, the method of solution and
some generalizations.Comment: RevTex, 10 pages in preprint form, no figure
Representation-theoretic derivation of the Temperley-Lieb-Martin algebras
Explicit expressions for the Temperley-Lieb-Martin algebras, i.e., the
quotients of the Hecke algebra that admit only representations corresponding to
Young diagrams with a given maximum number of columns (or rows), are obtained,
making explicit use of the Hecke algebra representation theory. Similar
techniques are used to construct the algebras whose representations do not
contain rectangular subdiagrams of a given size.Comment: 12 pages, LaTeX, to appear in J. Phys.
Characterization of actinomycetes antagonistic to Phytophthora fragariae var. rubi, the causal agent of raspberry root rot
Onze souches d'actinomycetes ayant la capacité de protéger les plants de framboisiers (Rubus strigosus) contre les infections causées par les Phytophthora ont été caractérisées. Il a été montré que toutes les souches appartenaient au genre Streptomyces. Deux souches (EF-34 et EF-76) croissaient à 4, 15 et 30°C sur un milieu V8 agar dont le pH avait été ajusté entre 5 et 9. Sept souches dont EF-34 et EF-76 pouvaient hydrolyser les parois cellulaires de Phytophthora et inhiber la croissance du champignon à 15°C et à des pH variant entre 5 et 9. Toutes les souches inhibaient la croissance du P. fragariae var. rubi et du Pythium ultimum. La croissance d'autres espÚces fongiques et de bactéries à Gram négatif n'était inhibée qu'en présence de trois souches (EF-14, EF-72 et EF-76). Les onze actinomycetes antagonistes ont été classés en quatre groupes selon leur résistance à divers pesticides utilisés pour protéger les cultures de framboisiers. La souche EF-76 a été caractérisée plus en détail. Cette souche a été identifiée comme étant le Streptomyces hygroscopicus var. geldanus, et produisait l'antibiotique geldanamycine.Eleven actinomycete strains that were previously shown to protect raspberry (Rubus strigosus) plants against Phytophthora infection were characterized. all were shown to belong to the genus Streptomyces. Two strains (EF-34 and EF-76) grew at 4, 15 and 30°C on V8 agar between pHs 5 to 9. Seven strains including EF-34 and EF-76 had both the ability to hydrolyze Phytophthora cell walls and to inhibit Phytophthora growth at 15°C between pHs 5 to 9. all actinomycetes inhibited the growth of P. fragariaevar. rubi and of Pythium ultimum. The growth of other fungal species and of Gram-negative bacteria was inhibited only in the presence of three strains (EF-14, EF-72, and EF-76). The eleven antagonistic actinomycetes were classified into four groups with regard to their resistance to various pesticides used to protect raspberry crops. Strain EF-76 was further characterized. This strain was identified as Streptomyceshygroscopicus var. geldanus, and it was shown to produce geldanamycin, a known antibiotic
Seedling emergence and yield performance of wheat cultivars depending on seed vigor and sowing density.
TĂtulo em portuguĂȘs: EmergĂȘncia de plĂąntulas e desempenho produtivo de cultivares de trigo em função do vigor de sementes e densidades de semeadura
Anyonic behavior of quantum group gases
We first introduce and discuss the formalism of -bosons and fermions
and consider the simplest Hamiltonian involving these operators. We then
calculate the grand partition function for these models and study the high
temperature (low density) case of the corresponding gases for . We show
that quantum group gases exhibit anyonic behavior in and spatial
dimensions. In particular, for a boson gas at the parameter
interpolates within a wider range of attractive and repulsive systems than the
anyon statistical parameter.Comment: LaTeX file, 19 pages, two figures ,uses epsf.st
Dynamics of Transformation from Segregation to Mixed Wealth Cities
We model the dynamics of the Schelling model for agents described simply by a
continuously distributed variable - wealth. Agents move to neighborhoods where
their wealth is not lesser than that of some proportion of their neighbors, the
threshold level. As in the case of the classic Schelling model where
segregation obtains between two races, we find here that wealth-based
segregation occurs and persists. However, introducing uncertainty into the
decision to move - that is, with some probability, if agents are allowed to
move even though the threshold level condition is contravened - we find that
even for small proportions of such disallowed moves, the dynamics no longer
yield segregation but instead sharply transition into a persistent mixed wealth
distribution. We investigate the nature of this sharp transformation between
segregated and mixed states, and find that it is because of a non-linear
relationship between allowed moves and disallowed moves. For small increases in
disallowed moves, there is a rapid corresponding increase in allowed moves, but
this tapers off as the fraction of disallowed moves increase further and
finally settles at a stable value, remaining invariant to any further increase
in disallowed moves. It is the overall effect of the dynamics in the initial
region (with small numbers of disallowed moves) that shifts the system away
from a state of segregation rapidly to a mixed wealth state.
The contravention of the tolerance condition could be interpreted as public
policy interventions like minimal levels of social housing or housing benefit
transfers to poorer households. Our finding therefore suggests that it might
require only very limited levels of such public intervention - just sufficient
to enable a small fraction of disallowed moves, because the dynamics generated
by such moves could spur the transformation from a segregated to mixed
equilibrium.Comment: 12 pages, 7 figure
- âŠ