414 research outputs found
Clearing algorithms and network centrality
I show that the solution of a standard clearing model commonly used in
contagion analyses for financial systems can be expressed as a specific form of
a generalized Katz centrality measure under conditions that correspond to a
system-wide shock. This result provides a formal explanation for earlier
empirical results which showed that Katz-type centrality measures are closely
related to contagiousness. It also allows assessing the assumptions that one is
making when using such centrality measures as systemic risk indicators. I
conclude that these assumptions should be considered too strong and that, from
a theoretical perspective, clearing models should be given preference over
centrality measures in systemic risk analyses
Dynamical phase transition for a quantum particle source
We analyze the time evolution describing a quantum source for noninteracting
particles, either bosons or fermions. The growth behaviour of the particle
number (trace of the density matrix) is investigated, leading to spectral
criteria for sublinear or linear growth in the fermionic case, but also
establishing the possibility of exponential growth for bosons. We further study
the local convergence of the density matrix in the long time limit and prove
the semiclassical limit.Comment: 24 pages; In the new version, we added several references concerning
open quantum systems and present an extended result on linear particle
production in the fermionic cas
A Kohn-Sham system at zero temperature
An one-dimensional Kohn-Sham system for spin particles is considered which
effectively describes semiconductor {nano}structures and which is investigated
at zero temperature. We prove the existence of solutions and derive a priori
estimates. For this purpose we find estimates for eigenvalues of the
Schr\"odinger operator with effective Kohn-Sham potential and obtain
-bounds of the associated particle density operator. Afterwards,
compactness and continuity results allow to apply Schauder's fixed point
theorem. In case of vanishing exchange-correlation potential uniqueness is
shown by monotonicity arguments. Finally, we investigate the behavior of the
system if the temperature approaches zero.Comment: 27 page
Wigner Measure Propagation and Conical Singularity for General Initial Data
We study the evolution of Wigner measures of a family of solutions of a
Schr\"odinger equation with a scalar potential displaying a conical
singularity. Under a genericity assumption, classical trajectories exist and
are unique, thus the question of the propagation of Wigner measures along these
trajectories becomes relevant. We prove the propagation for general initial
data.Comment: 24 pages, 1 figur
Planned observations of thermal plasma drifts and solar wind interactions in the Martian ionosphere
A Study of the Residual 39Ar Content in Argon from Underground Sources
The discovery of argon from underground sources with significantly less 39Ar
than atmospheric argon was an important step in the development of
direct-detection dark matter experiments using argon as the active target. We
report on the design and operation of a low background detector with a single
phase liquid argon target that was built to study the 39Ar content of the
underground argon. Underground argon from the Kinder Morgan CO2 plant in
Cortez, Colorado was determined to have less than 0.65% of the 39Ar activity in
atmospheric argon.Comment: 21 pages, 10 figure
New observations of molecular nitrogen in the Martian upper atmosphere by IUVS on MAVEN
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