660 research outputs found
Some results on the eigenfunctions of the quantum trigonometric Calogero-Sutherland model related to the Lie algebra E6
The quantum trigonometric Calogero-Sutherland models related to Lie algebras
admit a parametrization in which the dynamical variables are the characters of
the fundamental representations of the algebra. We develop here this approach
for the case of the exceptional Lie algebra E6.Comment: 17 pages, no figure
Optical spin transfer in ferromagnetic semiconductors
Circularly polarized laser pulses that excite electron-hole pairs across the
band gap of (III,Mn)V ferromagnetic semiconductors can be used to manipulate
and to study collective magnetization dynamics. The initial spin orientation of
a photocarrier in a (III,V) semiconductors is determined by the polarization
state of the laser. We show that the photocarrier spin can be irreversibly
transferred to the collective magnetization, whose dynamics can consequently be
flexibly controlled by suitably chosen laser pulses. As illustrations we
demonstrate the feasibility of all optical ferromagnetic resonance and optical
magnetization reorientation.Comment: 8 pages, 3 figure
On an approach for computing the generating functions of the characters of simple Lie algebras
We describe a general approach to obtain the generating functions of the
characters of simple Lie algebras which is based on the theory of the quantum
trigonometric Calogero-Sutherland model. We show how the method works in
practice by means of a few examples involving some low rank classical algebras
Quantum trigonometric Calogero-Sutherland model, irreducible characters and Clebsch-Gordan series for the exceptional algebra E7
We re-express the quantum Calogero-Sutherland model for the Lie algebra E7
and the particular value of the coupling constant K=1 by using the fundamental
irreducible characters of the algebra as dynamical variables. For that, we need
to develop a systematic procedure to obtain all the Clebsch-Gordan series
required to perform the change of variables. We describe how the resulting
quantum Hamiltonian operator can be used to compute more characters and
Clebsch-Gordan series for this exceptional algebra.Comment: 37 pages, 1 figur
Compaction caused by soil tillage and seedbed preparation: effects on weed emergence in a barley crop
El objetivo principal de este trabajo fue evaluar los efectos de la compactaciĂłn producida por la frecuencia de pases y el tipo de apero utilizado en la siembra del cereal, sobre la emergencia de las malas hierbas. Se utilizĂł un diseño en parcelas subdivididas con 4 repeticiones, con la labor primaria (fresa vs. cultivador) en parcelas principales y el pase de rulo (liso vs. pratenses) en subparcelas. Se tomaron datos de malas hierbas (densidad, biomasa) y de propiedades fĂsicas del suelo (compactaciĂłn, densidad aparente). Los resultados no han mostrado diferencias debidas a la labor primaria en ninguna de las variables analizadas, pero sĂ en funciĂłn del tipo y frecuencia de pases de rulo, observĂĄndose menor densidad y biomasa de malas hierbas cuanto mayor era el nĂșmero de pases de rulo, especialmente el liso, coincidiendo con los suelos mĂĄs compactados. Sin embargo, parece existir un lĂmite en el cual dejan de producirse efectos significativos debido a una sobrecompactaciĂłn (e.g. doble pase de rulo y zona de rodada).The main objective of this work was to evaluate the effects of the compaction produced by the frequency of passes and the type of implement used in seedbed preparation, on weed emergence. A split-plot design with 4 replications was used, with the primary tillage (cultivator vs. rotary tiller) in main plots and rolling (flat roller vs. Cambridge roller) in subplots. Weeds data (density, biomass) and soil physical properties (compaction, bulk density) were assessed. The results showed no differences due to the primary tillage in any of the analyzed variables. However, the type and frequency of roller passes resulted in significant differences in weed abundance, with lower weed density and biomass when the number of roller passes was greater (especially flat roller), which coincided with the higher compaction. However, it seems to be a limit at which significant effects no longer occur due to an overcompaction (e.g. double roller pass and tractor wheel traffic)
Electropolymerization of pyrrole from aqueous solutions on austenitic stainless steel electrodes
The elcctrochemical  polymerization of pyrrole (Py) in aqueous KN03 solutions using Austenitic stainless steel electrodes by galvanostatic, potentiostatic and potentiodynamic methods was studied. Chronoamperometric experiments show different behavior of the current with time. Correspondingly, 1-tx plots were made giving better fitting for x =3/2 suggesting a progressive nucleation with three-dimensional growth and, for x =-l /2 which indicate that diffusion is limiting the growth of the film. Chronopotentiograms are typical of a conducting polymer without any sign of passivation and, potentiodinamic curves indicate an irreversible electrodeposition
Quantum trigonometric Calogero-Sutherland model and irreducible characters for the exceptional algebra E8
We express the Hamiltonian of the quantum trigonometric Calogero-Sutherland
model for the Lie algebra E8 and coupling constant k=1 by using the fundamental
irreducible characters of the algebra as dynamical independent variables. Then,
we compute the second order characters of the algebra and some higher order
characters
Relativistically extended Blanchard recurrence relation for hydrogenic matrix elements
General recurrence relations for arbitrary non-diagonal, radial hydrogenic
matrix elements are derived in Dirac relativistic quantum mechanics. Our
approach is based on a generalization of the second hypervirial method
previously employed in the non-relativistic Schr\"odinger case. A relativistic
version of the Pasternack-Sternheimer relation is thence obtained in the
diagonal (i.e. total angular momentum and parity the same) case, from such
relation an expression for the relativistic virial theorem is deduced. To
contribute to the utility of the relations, explicit expressions for the radial
matrix elements of functions of the form and
---where is a Dirac matrix--- are presented.Comment: 21 pages, to be published in J. Phys. B: At. Mol. Opt. Phys. in Apri
Quantitative proteomics analysis of lymph nodes from pigs infected by porcine circovirus type 2(PCV2) by 2-DE, 18O/16O labeling and linear ion trap mass spectrometry
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