14,786 research outputs found
Bayesian T-optimal discriminating designs
The problem of constructing Bayesian optimal discriminating designs for a
class of regression models with respect to the T-optimality criterion
introduced by Atkinson and Fedorov (1975a) is considered. It is demonstrated
that the discretization of the integral with respect to the prior distribution
leads to locally T-optimal discrimination designs can only deal with a few
comparisons, but the discretization of the Bayesian prior easily yields to
discrimination design problems for more than 100 competing models. A new
efficient method is developed to deal with problems of this type. It combines
some features of the classical exchange type algorithm with the gradient
methods. Convergence is proved and it is demonstrated that the new method can
find Bayesian optimal discriminating designs in situations where all currently
available procedures fail.Comment: 25 pages, 3 figure
The finite mass beamsplitter in high power interferometers
The beamplitter in high-power interferometers is subject to significant
radiation-pressure fluctuations. As a consequence, the phase relations which
appear in the beamsplitter coupling equations oscillate and phase modulation
fields are generated which add to the reflected fields. In this paper, the
transfer function of the various input fields impinging on the beamsplitter
from all four ports onto the output field is presented including
radiation-pressure effects. We apply the general solution of the coupling
equations to evaluate the input-output relations of the dual-recycled
laser-interferometer topology of the gravitational-wave detector GEO600 and the
power-recycling, signal-extraction topology of advanced LIGO. We show that the
input-output relation exhibits a bright-port dark-port coupling. This mechanism
is responsible for bright-port contributions to the noise density of the output
field and technical laser noise is expected to decrease the interferometer's
sensitivity at low frequencies. It is shown quantitatively that the issue of
technical laser noise is unimportant in this context if the interferometer
contains arm cavities.Comment: 10 pages, 7 figure
Detection of Majorana Kramers pairs using a quantum point contact
We propose a setup that integrates a quantum point contact (QPC) and a
Josephson junction on a quantum spin Hall sample, experimentally realizable in
InAs/GaSb quantum wells. The confinement due to both the QPC and the
superconductor results in a Kramers pair of Majorana zero-energy bound states
when the superconducting phases in the two arms differ by an odd multiple of
across the Josephson junction. We investigate the detection of these
Majorana pairs with the integrated QPC, and find a robust switching from normal
to Andreev scattering across the edges due to the presence of Majorana Kramers
pairs. This transport signature is expected to be exhibited in measurements of
differential conductance and/or current cross-correlation at low bias
The location, clustering, and propagation of massive star formation in giant molecular clouds
Massive stars are key players in the evolution of galaxies, yet their
formation pathway remains unclear. In this work, we use data from several
galaxy-wide surveys to build an unbiased dataset of ~700 massive young stellar
objects (MYSOs), ~200 giant molecular clouds (GMCs), and ~100 young (<10 Myr)
optical stellar clusters (SCs) in the Large Magellanic Cloud. We employ this
data to quantitatively study the location and clustering of massive star
formation and its relation to the internal structure of GMCs. We reveal that
massive stars do not typically form at the highest column densities nor centers
of their parent GMCs at the ~6 pc resolution of our observations. Massive star
formation clusters over multiple generations and on size scales much smaller
than the size of the parent GMC. We find that massive star formation is
significantly boosted in clouds near SCs. Yet, whether a cloud is associated
with a SC does not depend on either the cloud's mass or global surface density.
These results reveal a connection between different generations of massive
stars on timescales up to 10 Myr. We compare our work with Galactic studies and
discuss our findings in terms of GMC collapse, triggered star formation, and a
potential dichotomy between low- and high-mass star formation.Comment: 13 pages, 7 figures, in pres
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