Articles
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07/09/1993--
07/09/1993
The impact of Stieltjes' work on continued fractions and orthogonal polynomials
Stieltjes' work on continued fractions and the orthogonal polynomials related
to continued fraction expansions is summarized and an attempt is made to
describe the influence of Stieltjes' ideas and work in research done after his
death, with an emphasis on the theory of orthogonal polynomials.
Walter Van Assche
11/28/2011--
11/18/2011
A remark on the ARE between Wilcoxon's and van~der~Waerden's scores
This paper is concerned with a comparison of van der Waerden's and Wilcoxon's
scores.
Nadir Maaroufi
Camille Sabbah
Yvik Swan
Thomas Verdebout
07/06/2015--
06/01/2015
Cayley transforms of su(2) representations
Cayley rational forms for rotations are given as explicit spin matrix
polynomials for any j. The results are compared to the Curtright-Fairlie-Zachos
matrix polynomials for rotations represented as exponentials.
T. S. Van Kortryk
02/15/2018--
02/15/2018
On the $L^p$ norm of the torsion unction
Bounds are obtained for the $L^p$ norm of the torsion function $v_{\Omega}$,
i.e. the solution of $-\Delta v=1,\, v\in H_0^1(\Omega),$ in terms of the
Lebesgue measure of $\Omega$ and the principal eigenvalue $\lambda_1(\Omega)$
of the Dirichlet Laplacian acting in $L^2(\Omega)$. We show that these bounds
are sharp for $1\le p\le 2$.
Michiel van den Berg
Thomas Kappeler
03/20/2003--
03/20/2003
Formation and Evolution of Compact Stellar X-ray Sources
In this chapter we review the formation and evolution of compact binaries
with neutron star and/or black hole components (i.e. LMXBs, HMXBs, binary
pulsars). After an introduction we discuss stellar evolution in binaries and
the processes involved in the mass-transfer phases of close binaries (RLO, CE,
ang.mom.loss) with radiative/convective hydrogen or helium donor stars. We also
describe the effects of accretion, asymmetric SN and systems merging as a
result of gravitational wave radiation.
Thomas M. Tauris
Ed van den Heuvel
07/09/1999--
07/06/1999
Local-energy density functionals for an N-dimensional electronic system in a magnetic field
We present a general approach for the construction of the exact
local-energy-density functionals for a uniform N-dimensional electronic system
in a magnetic field. For arbitrary dimension, we obtain explicit expressions
for the matter, kinetic, and exchange density functionals. In the zero-field
limit, we recover the usual N-dimensional Thomas-Fermi theory. As an
application of our results, we develop a current-density-functional theory, in
the spirit of the Thomas-Fermi-Dirac approximation, for an inhomogeneous
many-electron system in a magnetic field.
B. P. van Zyl
08/21/2000--
08/21/2000
Van Hove Singularities in the Quark-Gluon Plasma
General arguments as well as different approximations for the in-medium quark
propagator in a quark-gluon plasma lead to quark dispersion relations that
exhibit a minimum in one branch (plasmino). This minimum causes Van Hove
singularities in the dilepton production rate and mesonic correlators, which
might have observable consequences.
Markus H. Thoma
11/21/2011--
11/14/2011
On classical de Sitter solutions in higher dimensions
We derive necessary criteria for the existence of classical, meta-stable, de
Sitter solutions in flux compactifications of type II supergravity down to
dimensions higher than four. We find that the possibilities in higher
dimensions are much more restricted than in four dimensions. The only models
that satisfy the criteria are derived from O6 compactifications to D=5,6 and O5
compactifications to D=5 and no meta-stable solutions can exist in dimensions
higher than six. All these models have in common that the compact dimensions
are negatively curved.
Thomas Van Riet
04/17/2018--
04/03/2018
What if string theory has no de Sitter vacua?
We present a brief overview of attempts to construct de Sitter vacua in
string theory and explain how the results of this 20-year endeavor could point
to the fact that string theory harbors no de Sitter vacua at all. Making such a
statement is often considered controversial and "bad news for string theory".
We discuss how perhaps the opposite can be true.
Ulf H. Danielsson
Thomas Van Riet
05/19/2020--
05/19/2020
Smearing orientifolds in flux compactifications can be OK
We present explicit examples of supergravity solutions corresponding to
backreacting localised (non-intersecting) O6 planes in flux reductions of
massive IIA supergravity and address some criticism towards the very existence
of such solutions. We verify in detail how the smeared orientifold solution
becomes a good approximation to the localised solution in the large volume/weak
coupling limit, as expected. We also find an exotic solution where prior to
backreaction the internal space has a boundary and when backreaction is
included the boundary disappears and the space closes off. The exotic example
is however outside of the supergravity approximation everywhere.
Stephanie Baines
Thomas Van Riet
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