2,160 research outputs found
Superharmonic Perturbations of a Gaussian Measure, Equilibrium Measures and Orthogonal Polynomials
This work concerns superharmonic perturbations of a Gaussian measure given by
a special class of positive weights in the complex plane of the form , where is the logarithmic potential of
a compactly supported positive measure . The equilibrium measure of the
corresponding weighted energy problem is shown to be supported on subharmonic
generalized quadrature domains for a large class of perturbing potentials
. It is also shown that the matrix d-bar problem for
orthogonal polynomials with respect to such weights is well-defined and has a
unique solution given explicitly by Cauchy transforms. Numerical evidence is
presented supporting a conjectured relation between the asymptotic distribution
of the zeroes of the orthogonal polynomials in a semi-classical scaling limit
and the Schwarz function of the curve bounding the support of the equilibrium
measure, extending the previously studied case of harmonic polynomial
perturbations with weights supported on a compact domain.Comment: CRM preprint, 28 pages. To appear in: Complex Analysis and Operator
Theory (Special volume in honour of Bjorn Gustafsson). Two references added
(Oct. 2, 2008
Some Biorthogonal Families of Polynomials Arising in Noncommutative Quantum Mechanics
In this paper we study families of complex Hermite polynomials and construct
deformed versions of them, using a transformation. This
construction leads to the emergence of biorthogonal families of deformed
complex Hermite polynomials, which we then study in the context of a
two-dimensional model of noncommutative quantum mechanics.Comment: 17 page
Magnetic and Transport Properties of Fe-Ag granular multilayers
Results of magnetization, magnetotransport and Mossbauer spectroscopy
measurements of sequentially evaporated Fe-Ag granular composites are
presented. The strong magnetic scattering of the conduction electrons is
reflected in the sublinear temperature dependence of the resistance and in the
large negative magnetoresistance. The simultaneous analysis of the magnetic
properties and the transport behavior suggests a bimodal grain size
distribution. A detailed quantitative description of the unusual features
observed in the transport properties is given
XRound : A reversible template language and its application in model-based security analysis
Successful analysis of the models used in Model-Driven Development requires the ability to synthesise the results of analysis and automatically integrate these results with the models themselves. This paper presents a reversible template language called XRound which supports round-trip transformations between models and the logic used to encode system properties. A template processor that supports the language is described, and the use of the template language is illustrated by its application in an analysis workbench, designed to support analysis of security properties of UML and MOF-based models. As a result of using reversible templates, it is possible to seamlessly and automatically integrate the results of a security analysis with a model. (C) 2008 Elsevier B.V. All rights reserved
The intermediate-redshift galaxy cluster CL 0048-2942. Stellar populations
We present a detailed study of the cluster CL 0048-2942, located at z~0.64,
based on a photometric and spectroscopic catalogue of 54 galaxies in a 5 x 5
square arcmin region centred in that cluster. Of these, 23 galaxies were found
to belong to the cluster. Based on this sample, the line-of-sight velocity
dispersion of the cluster is approximately 680 +- 140 km/s. We have performed
stellar population synthesis in the cluster members as well as in the field
galaxies of the sample and found that there are population gradients in the
cluster with central galaxies hosting mainly intermediate/old populations
whereas galaxies in the cluster outskirts show clearly an increase of younger
populations, meaning that star formation is predominantly taking place in the
outer regions of the cluster. In a general way, field galaxies seem to host
less evolved stellar populations than cluster members. In fact, in terms of
ages, young supergiant stars dominate the spectra of field galaxies whereas
cluster galaxies display a dominant number of old and intermediate age stars.
Following the work of other authors (e.g. Dressler et al. 1999) we have
estimated the percentage of K+A galaxies in our sample and found around 13% in
the cluster and 10% in the field. These values were estimated through means of
a new method, based on stellar population synthesis results, that takes into
account all possible absorption features in the spectrum and thus makes optimal
use of the data.Comment: Accepted by Astronomy & Astrophysics. 24 pages, 10 figures, 10 tables
(figures 3, 4, 5 and tables 1, 3, 4, 5, 6, 7, 8 will be available in
electronic format only in the A&A published version
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