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An integral representation of an operator mean via the power means is
obtained. As an application, we shall give explicit condition of operator means
that the Ando-Hiai inequality holds.
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We study semi-inclusive charmless decays $B \to \pi X$, where $X$ does not
contain a charm (anti)quark. The mode $\bar B^0 \to \pi^- X$ turns out to be be
particularly useful for determination of the CKM matrix element $|V_{ub}|$. We
present the branching ratio (BR) of $\bar B^0 \to \pi^- X$ as a function of
$|V_{ub}|$, with an estimation of possible uncertainty. The BR is expected to
be an order of $10^{-4}$.
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Aims. A simplified model of jet power from active galactic nuclei is proposed
in which the relationship between jet power and disk luminosity is discussed by
combining disk accretion with two mechanisms of extracting energy magnetically
from a black hole accretion disk, i.e., the Blandford-Payne (BP) and the
Blandford-Znajek (BZ) processes.
Methods. By including the BP process into the conservation laws of mass,
angular momentum and energy, we derive the expressions of the BP power and disk
luminosity, and the jet power is regarded as the sum of the BZ and BP powers.
Results. We find that the disk radiation flux and luminosity decrease because
a fraction of the accretion energy is channelled into the outflow/jet in the BP
process. It is found that the dominant cooling mode of the accretion disk is
determined mainly by how the poloidal magnetic field decreases with the
cylindrical radius of the jet. By using the parameter space we found, which
consists of the black hole spin and the self-similar index of the configuration
of the poloidal magnetic field frozen in the disk, we were able to compare the
relative importance of the following quantities related to the jet production:
(1) the BP power versus the disk luminosity, (2) the BP power versus the BZ
power, and (3) the jet power versus the disk luminosity. In addition, we fit
the jet power and broad-line region luminosity of 11 flat-spectrum radio
quasars (FSRQs) and 17 steep-spectrum radio quasars (SSRQs) based on our model.
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The integrals defining the two-loop beta-function for the general
renormalizable N=1 supersymmetric Yang--Mills theory, regularized by higher
covariant derivatives, are investigated. It is shown that they are given by
integrals of double total derivatives. These integrals are not equal to zero
due to appearing of delta-functions. These delta-functions allow to reduce the
two-loop integrals to one-loop integrals, which can be easily calculated. The
result agrees with the exact NSVZ beta-function and calculations made by
different methods.
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We present molecular line observations of 13CO and C18O J=3-2, CN N = 3 - 2,
and CS J=7-6 lines in the protoplanetary disk around TW Hya at a high spatial
resolution of ~9 au (angular resolution of 0.15''), using the Atacama Large
Millimeter/Submillimeter Array. A possible gas gap is found in the deprojected
radial intensity profile of the integrated C18O line around a disk radius of
~58 au, slightly beyond the location of the au-scale dust clump at ~52 au,
which resembles predictions from hydrodynamic simulations of planet-disk
interaction. In addition, we construct models for the physical and chemical
structure of the TW Hya disk, taking account of the dust surface density
profile obtained from high spatial resolution dust continuum observations. As a
result, the observed flat radial profile of the CN line intensities is
reproduced due to a high dust-to-gas surface density ratio inside ~20 au.
Meanwhile, the CO isotopologue line intensities trace high temperature gas and
increase rapidly inside a disk radius of ~30 au. A model with either CO gas
depletion or depletion of gas-phase oxygen elemental abundance is required to
reproduce the relatively weak CO isotopologue line intensities observed in the
outer disk, consistent with previous atomic and molecular line observations
towards the TW Hya disk. {Further observations of line emission of
carbon-bearing species, such as atomic carbon and HCN, with high spatial
resolution would help to better constrain the distribution of elemental carbon
abundance in the disk gas.
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We prove that a countably compact space is monotonically retractable if and
only if it has a full retractional skeleton. In particular, a compact space is
monotonically retractable if and only if it is Corson. This gives an answer to
a question of R. Rojas-Hern{\'a}ndez and V. V. Tkachuk. Further, we apply this
result to characterize retractional skeleton using a topology on the space of
continuous functions, answering thus a question of the first author and a
related question of W. Kubi\'s.
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In this paper, we consider the infinite-dimensional integration problem on
weighted reproducing kernel Hilbert spaces with norms induced by an underlying
function space decomposition of ANOVA-type. The weights model the relative
importance of different groups of variables. We present new randomized
multilevel algorithms to tackle this integration problem and prove upper bounds
for their randomized error. Furthermore, we provide in this setting the first
non-trivial lower error bounds for general randomized algorithms, which, in
particular, may be adaptive or non-linear. These lower bounds show that our
multilevel algorithms are optimal. Our analysis refines and extends the
analysis provided in [F. J. Hickernell, T. M\"uller-Gronbach, B. Niu, K.
Ritter, J. Complexity 26 (2010), 229-254], and our error bounds improve
substantially on the error bounds presented there. As an illustrative example,
we discuss the unanchored Sobolev space and employ randomized quasi-Monte Carlo
multilevel algorithms based on scrambled polynomial lattice rules.
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We consider the simplest model for $T$ - linear growth of resistivity in
metals. It is shown that the so called "Planckian" limit for the temperature
dependent relaxation rate of electrons follows from a certain procedure for
representation of experimental data on resistivity and, in this sense, is a
kind of delusion.
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A linear program with linear complementarity constraints (LPCC) requires the
minimization of a linear objective over a set of linear constraints together
with additional linear complementarity constraints. This class has emerged as a
modeling paradigm for a broad collection of problems, including bilevel
programs, Stackelberg games, inverse quadratic programs, and problems involving
equilibrium constraints. The presence of the complementarity constraints
results in a nonconvex optimization problem. We develop a branch-and-cut
algorithm to find a global optimum for this class of optimization problems,
where we branch directly on complementarities. We develop branching rules and
feasibility recovery procedures and demonstrate their computational
effectiveness in a comparison with CPLEX. The implementation builds on CPLEX
through the use of callback routines. The computational results show that our
approach is a strong alternative to constructing an integer programming
formulation using big-$M$ terms to represent bounds for variables, with testing
conducted on general LPCCs as well as on instances generated from bilevel
programs with convex quadratic lower level problems.
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We study theoretically orbital effects of a parallel magnetic field applied
to a disordered superconducting film. We find that the field reduces the phase
stiffness and leads to strong quantum phase fluctuations driving the system
into an insulating behavior. This microscopic model shows that the critical
field decreases with the sheet resistance, in agreement with recent
experimental results. The predictions of this model can be used to discriminate
spin and orbital effects. We find that experiments conducted by A. Johansson
\textit{et al.} are more consistent with the orbital mechanism.
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In this paper, we consider the product-limit quantile estimator of an unknown
quantile function under a censored dependent model. This is a parallel problem
to the estimation of the unknown distribution function by the product-limit
estimator under the same model. Simultaneous strong Gaussian approximations of
the product-limit process and product-limit quantile process are constructed
with rate $O((\log n)^{-\lambda})$ for some $\lambda>0,$. The strong Gaussian
approximation of the product-limit process is then applied to derive the laws
of the iterated logarithm for product-limit process.
|
Background and Purpose: Various 'positive-contrast' neurographic methods have
been investigated for imaging the extracranial course of the facial nerve.
However, nerve visibility can be inconsistent with these sequences and may
depend on the composition of the parotid gland, limiting consistent
identification. To address this, we describe and evaluate a 'negative-contrast'
method for imaging of the extracranial facial nerve using three-dimensional
variable flip angle turbo spin echo (VFA-TSE) imaging. We investigate
strategies for further optimization, including parotid-specific VFA-TSE
optimization and the use of gadolinium-based contrast agent (GBCA). Materials
and Methods: 6 healthy volunteers and 10 patients with parotid tumors underwent
VFA-TSE and double echo steady state (DESS) imaging of the extracranial facial
nerve at 3T. The main trunk, divisions and branches of the extracranial facial
nerve were manually segmented by three radiologists, enabling CNR and Hausdorff
distance computation and confidence scoring. CNR, Hausdorff distance and
confidence scores were compared between sequences and between pre- and
post-contrast imaging to evaluate the effect of GBCA. Results: CNR, Hausdorff
distances and confidence scores were superior for VFA-TSE compared to DESS
imaging. GBCA administration produced a further increase in CNR of nerve
against parotid and improved differentiation of nerve from tumor. Conclusion:
Imaging of the extracranial facial nerve with VFA-TSE depicts the nerve as a
low signal structure ('black nerve') against the high signal parotid parenchyma
('white parotid') and outperforms positive-contrast DESS imaging in terms of
CNR, segmentation consistency and confidence. GBCA further increases negative
contrast and improves differentiation of nerve from tumor.
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Simplified models provide a useful way to study the impacts of a small number
of new particles on experimental observables and the interplay of those
observables, without the need to construct an underlying theory. In this study,
we perform global fits of simplified dark matter models with GAMBIT using an
up-to-date set of likelihoods for indirect detection, direct detection and
collider searches. We investigate models in which a scalar or fermionic dark
matter candidate couples to quarks via an s-channel vector mediator. Large
parts of parameter space survive for each model. In the case of Dirac or
Majorana fermion dark matter, excesses in LHC monojet searches and relic
density limits tend to prefer the resonance region, where the dark matter has
approximately half the mass of the mediator. A combination of vector and
axial-vector couplings to the Dirac candidate also leads to competing
constraints from direct detection and unitarity violation.
|
We introduce and study the classical and quantum mechanics of certain non
hyperbolic maps on the unit square. These maps are modifications of the usual
baker's map and their behaviour ranges from chaotic motion on the whole measure
to chaos on a set of measure zero. Thus we have called these maps ``lazy baker
maps.'' The aim of introducing these maps is to provide the simplest models of
systems with a mixed phase space, in which there are both regular and chaotic
motions. We find that despite the obviously contrived nature of these maps they
provide a good model for the study of the quantum mechanics of such systems. We
notice the effect of a classically chaotic fractal set of measure zero on the
corresponding quantum maps, which leads to a transition in the spectral
statistics. Some periodic orbits belonging to this fractal set are seen to scar
several eigenfunctions.
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I consider some promising future directions for quantum information theory
that could influence the development of 21st century physics. Advances in the
theory of the distinguishability of superoperators may lead to new strategies
for improving the precision of quantum-limited measurements. A better grasp of
the properties of multi-partite quantum entanglement may lead to deeper
understanding of strongly-coupled dynamics in quantum many-body systems,
quantum field theory, and quantum gravity.
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Discussion of "Harold Jeffreys's Theory of Probability revisited," by
Christian Robert, Nicolas Chopin, and Judith Rousseau, for Statistical Science
[arXiv:0804.3173]
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We analytically evaluate the Renyi entropies for the two dimensional free
boson CFT. The CFT is considered to be compactified on a circle and at finite
temperature. The Renyi entropies S_n are evaluated for a single interval using
the two point function of bosonic twist fields on a torus. For the case of the
compact boson, the sum over the classical saddle points results in the
Riemann-Siegel theta function associated with the A_{n-1} lattice. We then
study the Renyi entropies in the decompactification regime. We show that in the
limit when the size of the interval becomes the size of the spatial circle, the
entanglement entropy reduces to the thermal entropy of free bosons on a circle.
We then set up a systematic high temperature expansion of the Renyi entropies
and evaluate the finite size corrections for free bosons. Finally we compare
these finite size corrections both for the free boson CFT and the free fermion
CFT with the one-loop corrections obtained from bulk three dimensional
handlebody spacetimes which have higher genus Riemann surfaces as its boundary.
One-loop corrections in these geometries are entirely determined by quantum
numbers of the excitations present in the bulk. This implies that the leading
finite size corrections contributions from one-loop determinants of the
Chern-Simons gauge field and the Dirac field in the dual geometry should
reproduce that of the free boson and the free fermion CFT respectively. By
evaluating these corrections both in the bulk and in the CFT explicitly we show
that this expectation is indeed true.
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Let $\mathrm{X(n)}$ be Ravenel's Thom spectrum over $\Omega \mathrm{SU}(n)$.
We say a spectrum $E$ has chromatic defect $n$ if $n$ is the smallest positive
integer such that $E\otimes \mathrm{X(n)}$ is complex orientable. We compute
the chromatic defect of various examples of interest: finite spectra, the Real
Johnson--Wilson theories $\mathrm{ER(n)}$, the fixed points $\mathrm{EO}_n(G)$
of Morava $E$-theories with respect to a finite subgroup $G$ of the Morava
stabilizer group, and the connective image of $J$ spectrum j. Having finite
chromatic defect is closely related to the existence of analogues of the
classical Wood splitting $\mathrm{ko}\otimes C(\eta)\simeq \mathrm{ku}$. We
show that such splittings exist in quite a wide generality for fp spectra $E$.
When $E$ participates in such a splitting, $E$ admits a $\mathbb Z$-indexed
Adams--Novikov tower, which may be used to deduce differentials in the
Adams--Novikov spectral sequence of $E$.
|
In solving the problem of finding a temperature distribution which, at zero
temperature, corresponds to superfluidity, i.e., to nonzero energy, the author
tried to quantize free energy. This was done on the basis of supersecondary
quantization whose special case is the usual secondary quantization for bosons
and with the help of which new representations of the Schr\"odinger equation
were obtained. The supersecondary quantization allowed the author to construct
a variational method whose zero approximation are the Hartree-Fock and
Bogolyubov-BCSch variational principles. This method works especially well in
the case of not a large number of particles. The new quantization and the
variational method are of general character and can be used in the quantum
field theory.
|
This note presents a procedure of constructing a higher dimensional sphere
map from a lower dimensional one and gives an explicit formula for smooth
sphere map with a given degree. As an application a new proof of a generalized
Poincare-Hopf theorem called Morse index formula is also presented.
|
We study generalized fixed-point equations over idempotent semirings and
provide an efficient algorithm for the detection whether a sequence of Kleene's
iterations stabilizes after a finite number of steps. Previously known
approaches considered only bounded semirings where there are no infinite
descending chains. The main novelty of our work is that we deal with semirings
without the boundedness restriction. Our study is motivated by several
applications from interprocedural dataflow analysis. We demonstrate how the
reachability problem for weighted pushdown automata can be reduced to solving
equations in the framework mentioned above and we describe a few applications
to demonstrate its usability.
|
Image generation using generative AI is rapidly becoming a major new source
of visual media, with billions of AI generated images created using diffusion
models such as Stable Diffusion and Midjourney over the last few years. In this
paper we collect and analyse over 3 million prompts and the images they
generate. Using natural language processing, topic analysis and visualisation
methods we aim to understand collectively how people are using text prompts,
the impact of these systems on artists, and more broadly on the visual cultures
they promote. Our study shows that prompting focuses largely on surface
aesthetics, reinforcing cultural norms, popular conventional representations
and imagery. We also find that many users focus on popular topics (such as
making colouring books, fantasy art, or Christmas cards), suggesting that the
dominant use for the systems analysed is recreational rather than artistic.
|
Vector quantized diffusion (VQ-Diffusion) is a powerful generative model for
text-to-image synthesis, but sometimes can still generate low-quality samples
or weakly correlated images with text input. We find these issues are mainly
due to the flawed sampling strategy. In this paper, we propose two important
techniques to further improve the sample quality of VQ-Diffusion. 1) We explore
classifier-free guidance sampling for discrete denoising diffusion model and
propose a more general and effective implementation of classifier-free
guidance. 2) We present a high-quality inference strategy to alleviate the
joint distribution issue in VQ-Diffusion. Finally, we conduct experiments on
various datasets to validate their effectiveness and show that the improved
VQ-Diffusion suppresses the vanilla version by large margins. We achieve an
8.44 FID score on MSCOCO, surpassing VQ-Diffusion by 5.42 FID score. When
trained on ImageNet, we dramatically improve the FID score from 11.89 to 4.83,
demonstrating the superiority of our proposed techniques.
|
Roughly speaking, a conic bundle is a surface, fibered over a curve, such
that the fibers are conics (not necessarily smooth). We define stability for
conic bundles and construct a moduli space. We prove that (after fixing some
invariants) these moduli spaces are irreducible (under some conditions). Conic
bundles can be thought of as generalizations of orthogonal bundles on curves.
We show that in this particular case our definition of stability agrees with
the definition of stability for orthogonal bundles. Finally, in an appendix by
I. Mundet i Riera, a Hitchin-Kobayashi correspondence is stated for conic
bundles.
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We present an investigation of coherent backscattering of light that is
multiple scattered by a photonic crystal by using a broad-band technique. The
results significantly extend on previous backscattering measurements on
photonic crystals by simultaneously accessing a large frequency and angular
range. Backscatter cones around the stop gap are successfully modelled with
diffusion theory for a random medium. Strong variations of the apparent mean
free path and the cone enhancement are observed around the stop band. The
variations of the mean free path are described by a semi-empirical three-gap
model including band structure effects on the internal reflection and
penetration depth. A good match between theory and experiment is obtained
without the need of additional contributions of group velocity or density of
states. We argue that the cone enhancement reveals additional information on
directional transport properties that are otherwise averaged out in diffuse
multiple scattering.
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Given a graph G, we construct a convex polytope whose face poset is based on
marked subgraphs of G. Dubbed the graph multiplihedron, we provide a
realization using integer coordinates. Not only does this yield a natural
generalization of the multiphihedron, but features of this polytope appear in
works related to quilted disks, bordered Riemann surfaces, and operadic
structures. Certain examples of graph multiplihedra are related to Minkowski
sums of simplices and cubes and others to the permutohedron.
|
Babies born with low and very low birthweights -- i.e., birthweights below
2,500 and 1,500 grams, respectively -- have an increased risk of complications
compared to other babies, and the proportion of babies with a low birthweight
is a common metric used when evaluating public health in a population. While
many factors increase the risk of a baby having a low birthweight, many can be
linked to the mother's socioeconomic status, which in turn contributes to large
racial disparities in the incidence of low weight births. Here, we employ
Bayesian statistical models to analyze the proportion of babies with low
birthweight in Pennsylvania counties by race/ethnicity. Due to the small number
of births -- and low weight births -- in many Pennsylvania counties when
stratified by race/ethnicity, our methods must walk a fine line. On one hand,
leveraging spatial structure can help improve the precision of our estimates.
On the other hand, we must be cautious to avoid letting the model overwhelm the
information in the data and produce spurious conclusions. As such, we first
develop a framework by which we can measure (and control) the informativeness
of our spatial model. After demonstrating the properties of our framework via
simulation, we analyze the low birthweight data from Pennsylvania and examine
the extent to which the commonly used conditional autoregressive model can lead
to oversmoothing. We then reanalyze the data using our proposed framework and
highlight its ability to detect (or not detect) evidence of racial disparities
in the incidence of low birthweight.
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We show that the recently introduced logarithmic metrics used to predict
disease arrival times on complex networks are approximations of more general
network-based measures derived from random walks theory. Using the daily
air-traffic transportation data we perform numerical experiments to compare the
infection arrival time with this alternative metric that is obtained by
accounting for multiple walks instead of only the most probable path. The
comparison with direct simulations of arrival times reveals a higher
correlation compared to the shortest path approach used previously. In addition
our method allows to connect fundamental observables in epidemic spreading with
the cumulant generating function of the hitting time for a Markov chain. Our
results provides a general and computationally efficient approach to the
problem using only algebraic methods.
|
MAXI J1535-571 is a Galactic black hole candidate X-ray binary that was
discovered going into outburst in 2017 September. In this paper, we present
comprehensive radio monitoring of this system using the Australia Telescope
Compact Array (ATCA), as well as the MeerKAT radio observatory, showing the
evolution of the radio jet during its outburst. Our radio observations show the
early rise and subsequent quenching of the compact jet as the outburst
brightened and then evolved towards the soft state. We constrain the compact
jet quenching factor to be more than 3.5 orders of magnitude. We also detected
and tracked (for 303 days) a discrete, relativistically-moving jet knot that
was launched from the system. From the motion of the apparently superluminal
knot, we constrain the jet inclination (at the time of ejection) and speed to
$\leq 45^{\circ}$ and $\geq0.69$c, respectively. Extrapolating its motion back
in time, our results suggest that the jet knot was ejected close in time to the
transition from the hard intermediate state to soft intermediate state. The
launching event also occurred contemporaneously with a short increase in X-ray
count rate, a rapid drop in the strength of the X-ray variability, and a change
in the type-C quasi-periodic oscillation (QPO) frequency that occurs $>$2.5
days before the first appearance of a possible type-B QPO.
|
This document is one of the deliverable reports created for the ESCAPE
project. ESCAPE stands for Energy-efficient Scalable Algorithms for Weather
Prediction at Exascale. The project develops world-class, extreme-scale
computing capabilities for European operational numerical weather prediction
and future climate models. This is done by identifying Weather & Climate dwarfs
which are key patterns in terms of computation and communication (in the spirit
of the Berkeley dwarfs). These dwarfs are then optimised for different hardware
architectures (single and multi-node) and alternative algorithms are explored.
Performance portability is addressed through the use of domain specific
languages.
Atlas has been presented in deliverable D1.3. With this deliverable D2.3, a
first version of the Atlas software libraries is publicly released with a
permissive open-source license. The software is freely available for download,
and contains a user guide and installation instructions.
The Atlas libraries have been carefully designed with the user's perspective
in mind. Even though Atlas is mainly coded in C++, an equivalent Fortran
interface is presented without additional runtime overhead. The Fortran
interfaces are provided to accommodate existing NWP and climate models that
typically consist of Fortran subroutines. The mixed Fortran/C++ design enhances
interoperability between NWP and climate models and novel data management
techniques. Atlas provides interoperability with accelerator hardware, and can
serve as foundation to support higher level abstractions as used in domain
specific languages.
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Dynamics of complex social systems has often been described in the framework
of temporal networks, where links are considered to exist only at the moment of
interaction between nodes. Such interaction patterns are not only driven by
internal interaction mechanisms, but also affected by environmental changes. To
investigate the impact of the environmental changes on the dynamics of temporal
networks, we analyze several face-to-face interaction datasets using the
multiscale entropy (MSE) method to find that the observed temporal correlations
can be categorized according to the environmental similarity of datasets such
as classes and break times in schools. By devising and studying a temporal
network model considering a periodically changing environment as well as a
preferential activation mechanism, we numerically show that our model could
successfully reproduce various empirical results by the MSE method in terms of
multiscale temporal correlations. Our results demonstrate that the
environmental changes can play an important role in shaping the dynamics of
temporal networks when the interactions between nodes are influenced by the
environment of the systems.
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We underline some differences between the geometric aspect of Berezin's
approach to quantization on homogeneous K\"ahler manifolds and Bergman's
construction for bounded domains in $\mathbb{C}^n$. We construct explicitly the
Bergman representative coordinates for the Siegel-Jacobi disk
$\mathcal{D}^J_1$, which is a partially bounded manifold whose points belong to
$\mathbb{C}\times\mathcal{D}_1$, where $\mathcal{D}_1$ denotes the Siegel disk.
The Bergman representative coordinates on $\mathcal{D}^J_1$ are globally
defined, the Siegel-Jacobi disk is a normal K\"ahler homogeneous Lu Qi-Keng
manifold, whose representative manifold is the Siegel-Jacobi disk itself.
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We suggest a new experiment sensitive to a possible difference between the
amount of CP violation as measured on the surface of the Earth and in a lower
gravity environment. Our proposed experiment is model independent and could
yield a $5\sigma$ measurement within tens of days, indicating a dependence of
the level of CP violation in the neutral kaon system on the local gravitational
potential.
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We explore the possible observational signatures of different types of kink
modes (horizontal and vertical oscillations in their fundamental mode and
second harmonic) that may arise in coronal loops, with the aim of determining
how well the individual modes can be uniquely identified from time series of
images. A simple, purely geometrical model is constructed to describe the
different types of kink-mode oscillations. These are then `observed' from a
given direction. In particular, we employ the 3D geometrical parameters of 14
TRACE loops of transverse oscillations to try to identify the correct observed
wave mode. We find that for many combinations of viewing and loop geometry it
is not straightforward to distinguish between at least two types of kink modes
just using time series of images. We also considered Doppler signatures and
find that these can help obtain unique identifications of the oscillation modes
when employed in combination with imaging. We then compare the modeled spatial
signatures with the observations of 14 TRACE loops. We find that out of three
oscillations previously identified as fundamental horizontal mode oscillations,
two cases appear to be fundamental vertical mode oscillations (but possibly
combined with the fundamental horizontal mode), and one case appears to be a
combination of the fundamental vertical and horizontal modes, while in three
cases it is not possible to clearly distinguish between the fundamental mode
and the second-harmonic of the horizontal oscillation. In five other cases it
is not possible to clearly distinguish between a fundamental horizontal mode
and the second-harmonic of a vertical mode.
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We propose a new architecture for the learning of predictive spatio-temporal
motion models from data alone. Our approach, dubbed the Dropout Autoencoder
LSTM, is capable of synthesizing natural looking motion sequences over long
time horizons without catastrophic drift or motion degradation. The model
consists of two components, a 3-layer recurrent neural network to model
temporal aspects and a novel auto-encoder that is trained to implicitly recover
the spatial structure of the human skeleton via randomly removing information
about joints during training time. This Dropout Autoencoder (D-AE) is then used
to filter each predicted pose of the LSTM, reducing accumulation of error and
hence drift over time. Furthermore, we propose new evaluation protocols to
assess the quality of synthetic motion sequences even for which no ground truth
data exists. The proposed protocols can be used to assess generated sequences
of arbitrary length. Finally, we evaluate our proposed method on two of the
largest motion-capture datasets available to date and show that our model
outperforms the state-of-the-art on a variety of actions, including cyclic and
acyclic motion, and that it can produce natural looking sequences over longer
time horizons than previous methods.
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Affective computing is a field of study that focuses on developing systems
and technologies that can understand, interpret, and respond to human emotions.
Speech Emotion Recognition (SER), in particular, has got a lot of attention
from researchers in the recent past. However, in many cases, the publicly
available datasets, used for training and evaluation, are scarce and imbalanced
across the emotion labels. In this work, we focused on building a balanced
corpus from these publicly available datasets by combining these datasets as
well as employing various speech data augmentation techniques. Furthermore, we
experimented with different architectures for speech emotion recognition. Our
best system, a multi-modal speech, and text-based model, provides a performance
of UA(Unweighed Accuracy) + WA (Weighed Accuracy) of 157.57 compared to the
baseline algorithm performance of 119.66
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In this paper we describe the process of collection, transcription, and
annotation of recordings of spontaneous speech samples from Turkish-German
bilinguals, and the compilation of a corpus called TuGeBiC. Participants in the
study were adult Turkish-German bilinguals living in Germany or Turkey at the
time of recording in the first half of the 1990s. The data were manually
tokenised and normalised, and all proper names (names of participants and
places mentioned in the conversations) were replaced with pseudonyms.
Token-level automatic language identification was performed, which made it
possible to establish the proportions of words from each language. The corpus
is roughly balanced between both languages. We also present quantitative
information about the number of code-switches, and give examples of different
types of code-switching found in the data. The resulting corpus has been made
freely available to the research community.
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We explored the sparticle mass spectrum in light of the muon g-2 anomaly and
the little hierarchy problem in a class of gauge mediated supersymmetry
breaking model. Here the messenger fields transform in the adjoint
representation of the Standard Model gauge symmetry. To avoid unacceptably
light right-handed slepton masses the standard model is supplemented by
additional U(1)_B-L gauge symmetry. Considering a non-zero U(1)_B-L D-term
leads to an additional contribution to the soft supersymmetry breaking mass
terms which makes the right-handed slepton masses compatible with the current
experimental bounds. We show that in the framework of Lambda_{3}<0 and mu < 0,
the muon g-2 anomaly and the observed 125 GeV Higgs boson mass a can be
simultaneously accommodated. The slepton masses in this case are predicted to
lie in the few hundred GeV range, which can be tested at LHC. Despite the heavy
colored spectrum the the little hierarchy problem in this model can be
ameliorated and electroweak fine tuning parameter can be as low as 10 or so.
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Bimetric gravity is an interesting alternative to standard GR given its
potential to provide a concrete theoretical framework for a ghost-free massive
gravity theory. Here we investigate a class of Bimetric gravity models for
their cosmological implications. We study the background expansion as well as
the growth of matter perturbations at linear and second order. We use
low-redshift observations from SnIa (Pantheon+ and SH0ES), Baryon Acoustic
Oscillations (BAO), the growth ($f\sigma_{8}$) measurements and the measurement
from Megamaser Cosmology Project to constrain the Bimetric model. We find that
the Bimetric models are consistent with the present data alongside the
$\Lambda$CDM model. We reconstructed the `` effective dark energy equation of
state" ($\omega_{de}$) and "Skewness" ($S_{3}$) parameters for the Bimetric
model from the observational constraints and show that the current low-redshift
data allow significant deviations in $\omega_{de}$ and $S_{3}$ parameters with
respect to the $\Lambda$CDM behaviour. We also look at the ISW effect via
galaxy-temperature correlations and find that the best fit Bimetric model
behaves similarly to $\Lambda$CDM in this regard.
|
Bibliometrics such as the number of papers and times cited are often used to
compare researchers based on specific criteria. The criteria, however, are
different in each research domain and are set by empirical laws. Moreover,
there are arguments, such that the simple sum of metric values works to the
advantage of elders. Therefore, this paper attempts to constitute features from
time series data of bibliometrics, and then classify the researchers according
to the features. In detail, time series patterns are extracted from
bibliographic data sets, and then a model to classify whether the researchers
are "distinguished" or not is created by a machine learning technique. The
experiments achieved an F-measure of 80.0% in the classification of 114
researchers in two research domains based on the data sets of Japan Science and
Technology Agency and Elsevier's Scopus. In the future, we will conduct
verification on a number of researchers in several domains, and then make use
of discovering "distinguished" researchers, who are not widely known.
|
The limitation of the detection rate of standard bakelite resistive plate
chambers (RPC) used as muon detectors in the LHC experiments has prevented the
use of such detectors in the high rate regions in both CMS and ATLAS detectors.
One alternative to these detectors are RPCs made with low resistivity glass
plates ($10^{10} {\rm \Omega .cm}$), a beam test at DESY has shown that such
detectors can operate at few thousand Hz/cm$^2$ with high efficiency(> 90%)
|
The design of a building requires an architect to balance a wide range of
constraints: aesthetic, geometric, usability, lighting, safety, etc. At the
same time, there are often a multiplicity of diverse designs that can meet
these constraints equally well. Architects must use their skills and artistic
vision to explore these rich but highly constrained design spaces. A number of
computer-aided design tools use automation to provide useful analytical data
and optimal designs with respect to certain fitness criteria. However, this
automation can come at the expense of a designer's creative control.
We propose uDOME, a user-in-the-loop system for computer-aided design
exploration that balances automation and control by efficiently exploring,
analyzing, and filtering the space of environment layouts to better inform an
architect's decision-making. At each design iteration, uDOME provides a set of
diverse designs which satisfy user-defined constraints and optimality criteria
within a user defined parameterization of the design space. The user then
selects a design and performs a similar optimization with the same or different
parameters and objectives. This exploration process can be repeated as many
times as the designer wishes. Our user studies indicates that \DOME, with its
diversity-based approach, improves the efficiency and effectiveness of even
novice users with minimal training, without compromising the quality of their
designs.
|
The Spallation Neutron Source (SNS), located at Oak Ridge Laboratory in the
United States, will be coming online over the next few years. In addition to
producing fluxes of high-intensity neutrons, the interaction of the proton beam
with the liquid mercury target produces copious pions. The pi+ and subsequent
mu+ decay at rest, providing a neutrino beam comprising numu, nue, and
anti-numu components. This neutrino beam is ideal for high-precision neutrino
experiments. OscSNS is a proposed multi-purpose experiment that will perform a
search for light sterile neutrinos, search for beyond the Standard Model
interactions using neutrino oscillations, and provide tests of Standard Model
predictions through world-record precision neutrino cross section measurements.
OscSNS plans to submit a full proposal for funding in 2009.
|
QCD sum-rules are used to calculate the $\hat\rho(1^{-+})\to\pi\eta,
\pi\eta'$ decay widths of the exotic hybrid in two different $\eta-\eta'$
mixing schemes.
In the conventional flavour octet-singlet mixing scheme, the decay widths are
both found to be small, while in the recently-proposed quark mixing scheme, the
decay width $\Gamma_{\hat\rho\to\eta\pi}\approx 250 MeV$ is large compared with
the decay width $\Gamma_{\hat\rho\to\eta^\prime\pi}\approx 20 MeV$. These
results provide some insight into $\eta$-$\eta'$ mixing and hybrid decay
features.
|
We construct the ultraviolet completion of the Standard Model that contains
an infinite sequence of Hypercolor gauge groups. So, the whole gauge group of
the theory is $... \otimes SU(5)\otimes SU(4) \otimes SU(3) \otimes SU(2)
\otimes U(1)$. Here SU(4) is the Technicolor group of Farhi - Susskind model.
The breakdown of chiral symmetry due to the the Technicolor gives rise to
finite $W$ and $Z$ boson masses in a usual way. The other Hypercolor groups are
not confining. We suggest the hypothesis that the fermion masses are not
related in any way to technicolor gauge group. We suppose that the fermion mass
formation mechanism is related to the energies much higher than the technicolor
scale. Formally the fermion masses appear in our model as an external input. In
the construction of the theory we use essentially the requirement that it
posseses an additional discrete symmetry $\cal Z$ that is the continuation of
the $Z_6$ symmetry of the Standard Model. It has been found that there exists
such a choice of the hypercharges of the fermions that the chiral anomaly is
absent while the symmetry $\cal Z$ is preserved.
|
Features of the angular distributions of accelerated atomic projectiles at
grazing angles of incidence on the crystal surface are studied by using the
computer simulation. The interaction between the projectiles and the
crystal-lattice atoms and atomic structure of the crystal surface are
calculated by means of the electron density functional method. The angular
distributions of scattered projectiles are simulated by taking into account
their interaction with several atomic layers in the crystal lattice and atomic
thermal displacements. Good agreement between the calculated results and known
experimental data is achieved. A possibility of reconstructing the ion-atom
dynamic interaction potential from the dependence of the rainbow scattering
angle of nitrogen atoms under conditions of grazing incidence on the surface of
an aluminum crystal on the total kinetic energy of the accelerated atomic
particles is shown.
|
Procedural text understanding requires machines to reason about entity states
within the dynamical narratives. Current procedural text understanding
approaches are commonly \textbf{entity-wise}, which separately track each
entity and independently predict different states of each entity. Such an
entity-wise paradigm does not consider the interaction between entities and
their states. In this paper, we propose a new \textbf{scene-wise} paradigm for
procedural text understanding, which jointly tracks states of all entities in a
scene-by-scene manner. Based on this paradigm, we propose \textbf{S}cene
\textbf{G}raph \textbf{R}easoner (\textbf{SGR}), which introduces a series of
dynamically evolving scene graphs to jointly formulate the evolution of
entities, states and their associations throughout the narrative. In this way,
the deep interactions between all entities and states can be jointly captured
and simultaneously derived from scene graphs. Experiments show that SGR not
only achieves the new state-of-the-art performance but also significantly
accelerates the speed of reasoning.
|
The generalised Gegenbauer functions of fractional degree (GGF-Fs), denoted
by ${}^{r\!}G^{(\lambda)}_\nu(x)$ (right GGF-Fs) and
${}^{l}G^{(\lambda)}_\nu(x)$ (left GGF-Fs) with $x\in (-1,1),$ $\lambda>-1/2$
and real $\nu\ge 0,$ are special functions (usually non-polynomials), which are
defined upon the hypergeometric representation of the classical Gegenbauer
polynomial by allowing integer degree to be real fractional degree. Remarkably,
the GGF-Fs become indispensable for optimal error estimates of polynomial
approximation to singular functions, and have intimate relations with several
families of nonstandard basis functions recently introduced for solving
fractional differential equations. However, some properties of GGF-Fs, which
are important pieces for the analysis and applications, are unknown or under
explored. The purposes of this paper are twofold. The first is to show that for
$\lambda,\nu>0$ and $x=\cos\theta$ with $\theta\in (0,\pi),$
\begin{equation*}\label{IntRep-0N}
(\sin \varphi)^{\lambda}\,{}^{r\!}G_\nu^{(\lambda)}(\cos \varphi)=
\frac{2^\lambda\Gamma(\lambda+1/2)}{\sqrt{\pi} {(\nu+\lambda)^{\lambda}}} \,
{\cos ((\nu+\lambda)\varphi- \lambda\pi/2)}
+{\mathcal R}_\nu^{(\lambda)} (\varphi),
\end{equation*} and derive the precise expression of the "residual" term
${\mathcal R}_\nu^{(\lambda)} (\varphi).$ With this at our disposal, we obtain
the bounds of GGF-Fs uniform in $\nu.$ Under an appropriate weight function,
the bounds are uniform for $\theta\in [0,\pi]$ as well. Moreover, we can study
the asymptotics of GGF-Fs with large fractional degree $\nu.$ The second is to
present miscellaneous properties of GGF-Fs for better understanding of this
family of useful special functions.
|
Chiral properties of positive and negative parity nucleons, N and N*$, are
studied from the viewpoint of chiral symmetry. Two possible ways to assign
chiral transformations to the negative parity nucleon are considered. Using
linear sigma models based on the two chiral realizations, theoretical as well
as phenomenological consequences of the two different assignments are
investigated. We find that the nucleon mass in the chiral restored phase is the
key quantity to determine the meson-nucleon couplings and the axial charges of
nucleons. We also discuss the role of chiral symmetry breaking in the mass
splitting of N and N* in the two sigma models.
|
We discuss anharmonicity of the multi-octupole-phonon states in $^{208}$Pb
based on a covariant density functional theory, by fully taking into account
the interplay between the quadrupole and the octupole degrees of freedom. Our
results indicate the existence of a large anharmonicity in the transition
strengths, even though the excitation energies are similar to those in the
harmonic limit. We also show that the quadrupole-shape fluctuation
significantly enhances the fragmentation of the two-octupole-phonon states in
$^{208}$Pb. Using those transition strengths as inputs to coupled channels
calculations, we then discuss the fusion reaction of $^{16}$O+$^{208}$Pb at
energies around the Coulomb barrier. We show that the anharmonicity of the
octupole vibrational excitation considerably improves previous coupled-channels
calculations in the harmonic oscillator limit, significantly reducing the
height of the main peak in the fusion barrier distribution.
|
We establish an improved version of the Moser-Trudinger inequality in the
hyperbolic space $\mathbb H^n$, $n\geq 2$. Namely, we prove the following
result: for any $0 \leq \lambda < \left(\frac{n-1}n\right)^n$, then we have $$
\sup_{\substack{u\in C_0^\infty(\mathbb H^n) \int_{\mathbb H^n} |\nabla_g
u|_g^n d\text{Vol}_g -\lambda \int_{\mathbb H^n} |u|^n d\text{ Vol}_g \leq 1}}
\int_{\mathbb H^n} \Phi_n(\alpha_n |u|^{\frac{n}{n-1}}) d\text{ Vol}_g <
\infty, $$ where $\alpha_n = n \omega_{n-1}^{\frac1{n-1}}$, $\omega_{n-1}$
denotes the surface area of the unit sphere in $\mathbb R^n$ and $\Phi_n(t) =
e^t -\sum_{j=0}^{n-2}\frac{t^j}{j!}$. This improves the Moser-Trudinger
inequality in hyperbolic spaces obtained recently by Mancini and Sandeep, by
Mancini, Sandeep and Tintarev and by Adimurthi and Tintarev. In the limiting
case $\lambda =(\frac{n-1}n)^n$, we prove a Moser-Trudinger inequality with
exact growth in $\mathbb H^n$, $$ \sup_{\substack{u\in C_0^\infty(\mathbb H^n)
\int_{\mathbb H^n} |\nabla_g u|_g^n d\text{ Vol}_g -(\frac{n-1}n)^n
\int_{\mathbb H^n} |u|^n d\text{ Vol}_g \leq 1}} \frac{1}{\int_{\mathbb H^n}
|u|^n d\text{ Vol}_g}\int_{\mathbb H^n} \frac{\Phi_n(\alpha_n
|u|^{\frac{n}{n-1}})}{(1+ |u|)^{\frac n{n-1}}} d\text{ Vol}_g < \infty. $$ This
improves the Moser-Trudinger inequality with exact growth in $\mathbb H^n$
established by Lu and Tang.
|
We calculate the Curie temperature of layered ferromagnets, chromium
tri-iodide (CrI3), chromium tri-bromide (CrBr3), chromium germanium
tri-telluride (CrGeTe3), and the Neel temperature of a layered anti-ferromagnet
iron di-chloride (FeCl2), using first-principles density functional theory
calculations and Monte-Carlo simulations. We develop a computational method to
model the magnetic interactions in layered magnetic materials and calculate
their critical temperature. We provide a unified method to obtain the magnetic
exchange parameters (J) for an effective Heisenberg Hamiltonian from
first-principles, taking into account both the magnetic ansiotropy as well as
the out-of-plane interactions. We obtain the magnetic phase change behavior, in
particular the critical temperature, from the susceptibility and the
specific-heat, calculated using the three-dimensional Monte-Carlo (Metropolis)
algorithm. The calculated Curie temperatures for ferromagnetic materials (CrI3,
CrBr3 and CrGeTe3), match very well with experimental values. We show that the
interlayer interaction in bulk CrI3 with R3 stacking is significantly stronger
than the C2/m stacking, in line with experimental observations. We show that
the strong interlayer interaction in R3 CrI results in a competition between
the in-plane and the out-of-plane magnetic easy axis. Finally, we calculate the
Neel temperature of FeCl2 to be 47 +- 8 K, and show that the magnetic phase
transition in FeCl2 occurs in two steps with a high-temperature intralayer
ferromagnetic phase transition, and a low-temperature interlayer
anti-ferromagnetic phase transition.
|
We present the exact solution of the Baxter's three-color problem on a random
planar graph, using the random-matrix formulation of the problem, given by B.
Eynard and C. Kristjansen. We find that the number of three-coloring of an
infinite random graph is 0.9843 per vertex.
|
Electron-positron pair production is considered in the relativistic collision
of a nucleus and an anti-nucleus, in which both leptons are created in bound
states of the corresponding nucleus-lepton system. Compared to free and
bound-free pair production this process is shown to display a qualitatively
different dependency both on the impact energy and charged of the colliding
particles. Interestingly, at high impact energies the cross section for this
process is found to be larger than that for the analogous atomic process of
non-radiative electron capture although the latter does not involve the
creation of new particles.
|
Vortex is a universal and significant phenomenon that has been known for
centuries. However, creating vortices to the atomic limit has remained elusive
because that the characteristic length to support a vortex is usually much
larger than the atomic scale. Very recently, it was demonstrated that
intervalley scattering induced by the single carbon defect of graphene leads to
phase winding over a closed path surrounding the defect. Motivated by this, we
demonstrate, in this Letter, that the single carbon defects at A and B
sublattices of graphene can be regarded as pseudospin-mediated atomic-scale
vortices with angular momenta l = +2 and -2, respectively. The quantum
interferences measurements of the interacting vortices indicate that the
vortices cancel each other, resulting in zero total angular momentum, in the
|A| = |B| case, and they show aggregate chirality and angular momenta similar
to a single vortex of the majority in the |A| not equal to |B| case, where |A|
(|B|) is the number of vortices with angular momenta l = +2 (l = -2).
|
Recent advancements in Large Language Models have transformed ML/AI
development, necessitating a reevaluation of AutoML principles for the
Retrieval-Augmented Generation (RAG) systems. To address the challenges of
hyper-parameter optimization and online adaptation in RAG, we propose the
AutoRAG-HP framework, which formulates the hyper-parameter tuning as an online
multi-armed bandit (MAB) problem and introduces a novel two-level Hierarchical
MAB (Hier-MAB) method for efficient exploration of large search spaces. We
conduct extensive experiments on tuning hyper-parameters, such as top-k
retrieved documents, prompt compression ratio, and embedding methods, using the
ALCE-ASQA and Natural Questions datasets. Our evaluation from jointly
optimization all three hyper-parameters demonstrate that MAB-based online
learning methods can achieve Recall@5 $\approx 0.8$ for scenarios with
prominent gradients in search space, using only $\sim20\%$ of the LLM API calls
required by the Grid Search approach. Additionally, the proposed Hier-MAB
approach outperforms other baselines in more challenging optimization
scenarios. The code will be made available at https://aka.ms/autorag.
|
The chiral QED$_3$--Gross-Neveu-Yukawa (QED$_3$-GNY) theory is a
$2+1$-dimensional U(1) gauge theory with $N_f$ flavors of four-component Dirac
fermions coupled to a scalar field. For $N_f=1$, the specific chiral Ising
QED$_3$-GNY model has recently been conjectured to be dual to the deconfined
quantum critical point that describes Neel--valence-bond-solid transition of
frustrated quantum magnets on square lattice. We study the universal critical
behaviors of the chiral QED$_3$-GNY model in $d=4-\epsilon$ dimensions for an
arbitrary $N_f$ . We calculate the boson anomalous dimensions, inverse
correlation length exponent, as well as the scaling dimensions of nonsinglet
fermion bilinear in the chiral QED$_3$-GNY model. The Pad$\acute{e}$ estimates
for the exponents are obtained in the chiral Ising-, XY- and
Heisenberg-QED$_3$-GNY universality class respectively. We also establish the
general condition of the supersymmetric criticality for the ungauged
QED$_3$-GNY model. For the conjectured duality between chiral QED$_3$-GNY
critical point and deconfined quantum critical point, we find the inverse
correlation length exponent has a lower boundary $\nu^{-1}>0.75$, beyond which
the Ising-QED$_3$-GNY--$\mathbb{C}$P$^1$ duality may hold.
|
In this invited response we answer all comments by Engelen and Hansen
[arXiv:2207.07844]. We point out that the superfluid and superconductive
properties of H(0) have been published previously. We explain some differences
between covalently bonded molecules and the molecules in the ultradense matter
H(0) form, and explain some aspects of the energetics of H(0) molecules during
Coulomb explosions. We point out that the experimental spectra shown in our
publication are not ion time-of-flight spectra but neutral time-of-flight
spectra with the peak width given by the internal energetics and not by
experimental factors. We point out that no phase diagram has been measured for
H(0). Further we point out that a Rydberg state is a hydrogenic state and thus
that all hydrogen atom states are Rydberg states. That Rydberg states always
have large principal quantum numbers is a complete misunderstanding. We point
out that a QM description of H(0) is published. We point out that the
internuclear distances in p(0), D(0) and pD(0) have been measured by rotational
spectroscopy in two publications for three different spin states. They are
measured in the pm range with fm precision.
|
We propose an improved analytical model for the horizon-absorbed
gravitational-wave energy flux of a small body in circular orbit in the
equatorial plane of a Kerr black hole. Post-Newtonian (PN) theory provides an
analytical description of the multipolar components of the absorption flux
through Taylor expansions in the orbital frequency. Building on previous work,
we construct a mode-by-mode factorization of the absorbed flux whose Taylor
expansion agrees with current PN results. This factorized form significantly
improves the agreement with numerical results obtained with a frequency-domain
Teukolsky code, which evolves through a sequence of circular orbits up to the
photon orbit. We perform the comparison between model and numerical data for
dimensionless Kerr spins $-0.99 \leq q \leq 0.99$ and for frequencies up to the
light ring of the Kerr black hole. Our proposed model enforces the presence of
a zero in the flux at an orbital frequency equal to the frequency of the
horizon, as predicted by perturbation theory. It also reproduces the expected
divergence of the flux close to the light ring. Neither of these features are
captured by the Taylor-expanded PN flux. Our proposed absorption flux can also
help improve models for the inspiral, merger, ringdown of small mass-ratio
binary systems.
|
The quality of output from large language models (LLMs), particularly in
machine translation (MT), is closely tied to the quality of in-context examples
(ICEs) provided along with the query, i.e., the text to translate. The
effectiveness of these ICEs is influenced by various factors, such as the
domain of the source text, the order in which the ICEs are presented, the
number of these examples, and the prompt templates used. Naturally, selecting
the most impactful ICEs depends on understanding how these affect the resulting
translation quality, which ultimately relies on translation references or human
judgment. This paper presents a novel methodology for in-context learning (ICL)
that relies on a search algorithm guided by domain-specific quality estimation
(QE). Leveraging the XGLM model, our methodology estimates the resulting
translation quality without the need for translation references, selecting
effective ICEs for MT to maximize translation quality. Our results demonstrate
significant improvements over existing ICL methods and higher translation
performance compared to fine-tuning a pre-trained language model (PLM),
specifically mBART-50.
|
Continuous analogs of orthogonal polynomials on the circle are solutions of a
canonical system of differential equations, introduced and studied by M.G.Krein
and recently generalized to matrix systems by L.A.Sakhnovich. We prove that the
continuous analog of the adjoint polynomials converges in the upper half-plane
in the case of L^2 coefficients, but in general the limit can be defined only
up to a constant multiple even when the coefficients are in L^p for any p>2,
the spectral measure is absolutely continuous and the Szego-Kolmogorov-Krein
condition is satisfied. Thus we point out that Krein's and Sakhnovich's papers
contain an inaccuracy, which does not undermine known implications from these
results.
|
The critical regime of the charge exchange (CE) manganite spin glass
Eu_{0.5}Ba_{0.5}MnO_{3} is investigated using linear and non linear magnetic
susceptibility and the divergence of the third ordered susceptibility (chi{_3})
signifying the onset of a conventional freezing transition is experimentally
demonstrated. The divergence in chi{_3}, dynamical scaling of the linear
susceptibility and relevant scaling equations are used to determine the
critical exponents associated with this freezing transition, the values of
which match well with the 3D Ising universality class. Magnetic field
dependence of the spin glass response function is used to estimate the spin
correlation length which is seen to be larger than the charge/orbital
correlation length reported in this system.
|
Unsupervised Domain Adaptation (UDA) aims at improving the generalization
capability of a model trained on a source domain to perform well on a target
domain for which no labeled data is available. In this paper, we consider the
semantic segmentation of urban scenes and we propose an approach to adapt a
deep neural network trained on synthetic data to real scenes addressing the
domain shift between the two different data distributions. We introduce a novel
UDA framework where a standard supervised loss on labeled synthetic data is
supported by an adversarial module and a self-training strategy aiming at
aligning the two domain distributions. The adversarial module is driven by a
couple of fully convolutional discriminators dealing with different domains:
the first discriminates between ground truth and generated maps, while the
second between segmentation maps coming from synthetic or real world data. The
self-training module exploits the confidence estimated by the discriminators on
unlabeled data to select the regions used to reinforce the learning process.
Furthermore, the confidence is thresholded with an adaptive mechanism based on
the per-class overall confidence. Experimental results prove the effectiveness
of the proposed strategy in adapting a segmentation network trained on
synthetic datasets like GTA5 and SYNTHIA, to real world datasets like
Cityscapes and Mapillary.
|
Towards characterizing the optimization landscape of games, this paper
analyzes the stability of gradient-based dynamics near fixed points of
two-player continuous games. We introduce the quadratic numerical range as a
method to characterize the spectrum of game dynamics and prove the robustness
of equilibria to variations in learning rates. By decomposing the game Jacobian
into symmetric and skew-symmetric components, we assess the contribution of a
vector field's potential and rotational components to the stability of
differential Nash equilibria. Our results show that in zero-sum games, all Nash
are stable and robust; in potential games, all stable points are Nash. For
general-sum games, we provide a sufficient condition for instability. We
conclude with a numerical example in which learning with timescale separation
results in faster convergence.
|
We study deep neural networks for classification of images with quality
distortions. We first show that networks fine-tuned on distorted data greatly
outperform the original networks when tested on distorted data. However,
fine-tuned networks perform poorly on quality distortions that they have not
been trained for. We propose a mixture of experts ensemble method that is
robust to different types of distortions. The "experts" in our model are
trained on a particular type of distortion. The output of the model is a
weighted sum of the expert models, where the weights are determined by a
separate gating network. The gating network is trained to predict optimal
weights for a particular distortion type and level. During testing, the network
is blind to the distortion level and type, yet can still assign appropriate
weights to the expert models. We additionally investigate weight sharing
methods for the mixture model and show that improved performance can be
achieved with a large reduction in the number of unique network parameters.
|
Cancer has relational information residing at varying scales, modalities, and
resolutions of the acquired data, such as radiology, pathology, genomics,
proteomics, and clinical records. Integrating diverse data types can improve
the accuracy and reliability of cancer diagnosis and treatment. There can be
disease-related information that is too subtle for humans or existing
technological tools to discern visually. Traditional methods typically focus on
partial or unimodal information about biological systems at individual scales
and fail to encapsulate the complete spectrum of the heterogeneous nature of
data. Deep neural networks have facilitated the development of sophisticated
multimodal data fusion approaches that can extract and integrate relevant
information from multiple sources. Recent deep learning frameworks such as
Graph Neural Networks (GNNs) and Transformers have shown remarkable success in
multimodal learning. This review article provides an in-depth analysis of the
state-of-the-art in GNNs and Transformers for multimodal data fusion in
oncology settings, highlighting notable research studies and their findings. We
also discuss the foundations of multimodal learning, inherent challenges, and
opportunities for integrative learning in oncology. By examining the current
state and potential future developments of multimodal data integration in
oncology, we aim to demonstrate the promising role that multimodal neural
networks can play in cancer prevention, early detection, and treatment through
informed oncology practices in personalized settings.
|
We show that, for Finsler spaces with cubic metric, Landsberg spaces are
Berwaldian. Also, for decomposable metrics, we determine specific conditions
for a space with cubic metric to be of Berwald type, thus refining the result
in [6].
|
There are p heterogeneous objects to be assigned to n competing agents (n >
p) each with unit demand. It is required to design a Groves mechanism for this
assignment problem satisfying weak budget balance, individual rationality, and
minimizing the budget imbalance. This calls for designing an appropriate rebate
function. Our main result is an impossibility theorem which rules out linear
rebate functions with non-zero efficiency in heterogeneous object assignment.
Motivated by this theorem, we explore two approaches to get around this
impossibility. In the first approach, we show that linear rebate functions with
non-zero are possible when the valuations for the objects are correlated. In
the second approach, we show that rebate functions with non-zero efficiency are
possible if linearity is relaxed.
|
Magnetic-field control of fundamental optical properties is a crucial
challenge in the engineering of multifunctional microdevices. Van der Waals
(vdW) magnets retaining a magnetic order even in atomically thin layers, offer
a promising platform for hosting exotic magneto-optical functionalities owing
to their strong spin-charge coupling. Here, we demonstrate that a giant optical
anisotropy can be controlled by magnetic fields in the vdW magnet FePS$_3$. The
giant linear dichroism ($\sim$11%), observed below $T_{\text{N}}\!\sim\!120$ K,
is nearly fully suppressed in a wide energy range from 1.6 to 2.0 eV, following
the collapse of the zigzag magnetic order above 40 T. This remarkable
phenomenon can be explained as a result of symmetry changes due to the spin
order, enabling minority electrons of Fe$^{2+}$ to hop in a honeycomb lattice.
The modification of spin-order symmetry by external fields provides a novel
route for controllable anisotropic optical micro-devices.
|
In this study, we present the original method for reconstructing the
potential of interparticle interaction from statistically averaged structural
data, namely, the radial distribution function of particles in many-particle
system. This method belongs to a family of machine learning methods and is
implemented through the differential evolution algorithm. As demonstrated for
the case of the Lennard-Jones liquid taken as an example, there is no
one-to-one correspondence between structure and potential of interparticle
interaction of a many-particle disordered system at a certain thermodynamic
state. Namely, a whole family of the Mie potentials determined by two
parameters $p_{ 1 }$ and $p_{ 2 }$ related to each other according to a certain
rule can reproduce properly a unique structure of the Lennard-Jones liquid at a
given thermodynamic state. It is noteworthy that this family of the potentials
quite correctly reproduces for the Lennard-Jones liquid the transport
properties (in particular, the self-diffusion coefficient) over a temperature
range as well as the dynamic structure factor, which is one of the key
characteristics of the collective dynamics of particles.
|
We derive the modifications introduced by extra-spatial dimensions beyond the
four dimensional spacetime on the macroscopic properties of neutron stars,
which in turn affect the gravitational wave spectrum of their binaries. It
turns out that the mass-radius relation of the neutron stars, and their tidal
deformability, are affected non-trivially by the presence of extra dimensions,
and can be used to constrain parameters associated with those dimensions.
Implications for I-Love-Q universality relations are also discussed and
utilized to obtain a constraint on one such parameter. Importantly, we show,
for the first time, that measurements of the component masses and tidal
deformabilities of the binary neutron star system GW170817, constrain the brane
tension in the single brane-world model of Randall and Sundrum to be greater
than $35.1~\textrm{GeV}^{4}$. This work opens up the possibility of making such
a constraint more robust by improving the modelling of binaries on the brane in
the future.
|
Recent studies have suggested that the stability of peer-to-peer networks may
rely on persistent peers, who dwell on the network after they obtain the entire
file. In the absence of such peers, one piece becomes extremely rare in the
network, which leads to instability. Technological developments, however, are
poised to reduce the incidence of persistent peers, giving rise to a need for a
protocol that guarantees stability with non-persistent peers. We propose a
novel peer-to-peer protocol, the group suppression protocol, to ensure the
stability of peer-to-peer networks under the scenario that all the peers adopt
non-persistent behavior. Using a suitable Lyapunov potential function, the
group suppression protocol is proven to be stable when the file is broken into
two pieces, and detailed experiments demonstrate the stability of the protocol
for arbitrary number of pieces. We define and simulate a decentralized version
of this protocol for practical applications. Straightforward incorporation of
the group suppression protocol into BitTorrent while retaining most of
BitTorrent's core mechanisms is also presented. Subsequent simulations show
that under certain assumptions, BitTorrent with the official protocol cannot
escape from the missing piece syndrome, but BitTorrent with group suppression
does.
|
Chern-Simons gauge theory for compact semisimple groups is analyzed from a
perturbation theory point of view. The general form of the perturbative series
expansion of a Wilson line is presented in terms of the Casimir operators of
the gauge group. From this expansion new numerical knot invariants are
obtained. These knot invariants turn out to be of finite type (Vassiliev
invariants), and to possess an integral representation. Using known results
about Jones, HOMFLY, Kauffman and Akutsu-Wadati polynomial invariants these new
knot invariants are computed up to type six for all prime knots up to six
crossings. Our results suggest that these knot invariants can be normalized in
such a way that they are integer-valued.
|
In this paper, first, we review a straightforward analytical technique based
on image impedance concept for designing traditional microwave microstrip
coupled line filters using distributed elements. In the introduced approach, we
characterize a quarter-wave coupled line section, and then these discrete
sections can be connected in series to synthesis the final desired frequency
response. Next, we use a novel open-stub based technique to suppress spurious
harmonic frequencies. Finally, using proposed technique, we design and simulate
a band pass filter (BPF). The simulation results prove the usefulness of the
proposed technique.
|
Localization methods have produced explicit expressions for the sphere
partition functions of (2,2) superconformal field theories. The mirror symmetry
conjecture predicts an IR duality between pairs of Abelian gauged linear sigma
models, a class of which describe families of Calabi-Yau manifolds realizable
as complete intersections in toric varieties. We investigate this prediction
for the sphere partition functions and find agreement between that of a model
and its mirror up to the scheme-dependent ambiguities inherent in the
definitions of these quantities.
|
We build a cartesian closed category, called Cho, based on event structures.
It allows an interpretation of higher-order stateful concurrent programs that
is refined and precise: on the one hand it is conservative with respect to
standard Hyland-Ong games when interpreting purely functional programs as
innocent strategies, while on the other hand it is much more expressive. The
interpretation of programs constructs compositionally a representation of their
execution that exhibits causal dependencies and remembers the points of
non-deterministic branching.The construction is in two stages. First, we build
a compact closed category Tcg. It is a variant of Rideau and Winskel's category
CG, with the difference that games and strategies in Tcg are equipped with
symmetry to express that certain events are essentially the same. This is
analogous to the underlying category of AJM games enriching simple games with
an equivalence relations on plays. Building on this category, we construct the
cartesian closed category Cho as having as objects the standard arenas of
Hyland-Ong games, with strategies, represented by certain events structures,
playing on games with symmetry obtained as expanded forms of these arenas.To
illustrate and give an operational light on these constructions, we interpret
(a close variant of) Idealized Parallel Algol in Cho.
|
Graph representation learning has become a hot research topic due to its
powerful nonlinear fitting capability in extracting representative node
embeddings. However, for sequential data such as speech signals, most
traditional methods merely focus on the static graph created within a sequence,
and largely overlook the intrinsic evolving patterns of these data. This may
reduce the efficiency of graph representation learning for sequential data. For
this reason, we propose an adaptive graph representation learning method based
on dynamically evolved graphs, which are consecutively constructed on a series
of subsequences segmented by a sliding window. In doing this, it is better to
capture local and global context information within a long sequence. Moreover,
we introduce a weighted approach to update the node representation rather than
the conventional average one, where the weights are calculated by a novel
matrix computation based on the degree of neighboring nodes. Finally, we
construct a learnable graph convolutional layer that combines the graph
structure loss and classification loss to optimize the graph structure. To
verify the effectiveness of the proposed method, we conducted experiments for
speech emotion recognition on the IEMOCAP and RAVDESS datasets. Experimental
results show that the proposed method outperforms the latest (non-)graph-based
models.
|
We present experimental and numerical studies of broad-area semiconductor
lasers with chaotic ray dynamics. The emission intensity distributions at the
cavity boundaries are measured and compared to ray tracing simulations and
numerical calculations of the passive cavity modes. We study two different
cavity geometries, a D-cavity and a stadium, both of which feature fully
chaotic ray dynamics. While the far-field distributions exhibit fairly
homogeneous emission in all directions, the emission intensity distributions at
the cavity boundary are highly inhomogeneous, reflecting the non-uniform
intensity distributions inside the cavities. The excellent agreement between
experiments and simulations demonstrates that the intensity distributions of
wave-chaotic semiconductor lasers are primarily determined by the cavity
geometry. This is in contrast to conventional Fabry-Perot broad-area lasers for
which the intensity distributions are to a large degree determined by the
nonlinear interaction of the lasing modes with the semiconductor gain medium.
|
The motion of gravitational axion-like particles (ALP) around a Kerr black
hole is analyzed, paying attention to resonance and distribution of spectral
radiation. We first discuss the computation of $\sqrt{g}{\tilde R}_{\mu \nu
\rho \rho \sigma}R^{\mu \nu \rho \sigma}$ and its implications with
Pontryagin's theorem and a detailed analysis of Teukolsky's master equation is
done. After carefully analyzing the Teukolsky master equation, we show that
this system exhibits resonance when $\omega \gtrsim \mu$ where $\mu$ is the
mass of the ALP. A skew-normal distribution can approximate the energy
distribution, and we can calculate the mean lifetime of the resonance for black
holes with masses between 100 to 1000 $M_{\odot}$. This range corresponds to a
duration between $10^{-1}$s and $10^{41}$s, the observation range used in LIGO
data.
|
This paper proposes a novel differentiable architecture search method by
formulating it into a distribution learning problem. We treat the continuously
relaxed architecture mixing weight as random variables, modeled by Dirichlet
distribution. With recently developed pathwise derivatives, the Dirichlet
parameters can be easily optimized with gradient-based optimizer in an
end-to-end manner. This formulation improves the generalization ability and
induces stochasticity that naturally encourages exploration in the search
space. Furthermore, to alleviate the large memory consumption of differentiable
NAS, we propose a simple yet effective progressive learning scheme that enables
searching directly on large-scale tasks, eliminating the gap between search and
evaluation phases. Extensive experiments demonstrate the effectiveness of our
method. Specifically, we obtain a test error of 2.46% for CIFAR-10, 23.7% for
ImageNet under the mobile setting. On NAS-Bench-201, we also achieve
state-of-the-art results on all three datasets and provide insights for the
effective design of neural architecture search algorithms.
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One of the important consequences of the no-force condition for BPS states is
the existence of stable static multi-center solutions, at least in ungauged
supergravities. This observation has been at the heart of many developments in
brane physics, including the construction of intersecting branes and reduced
symmetry D-brane configurations corresponding to the Coulomb branch of the
gauge theory. However the search for multi-center solutions to gauged
supergravities has proven rather elusive. Because of the background curvature,
it appears such solutions cannot be static. Nevertheless even allowing for time
dependence, general multi-center solutions to gauged supergravity have yet to
be constructed. In this letter we investigate the construction of such
solutions for the case of D=5, N=2 gauged supergravity coupled to an arbitrary
number of vector multiplets. Formally, we find a family of time dependent
multi-center black hole solutions which are easily generalized to the case of
AdS supergravities in general dimensions. While these are not true solutions,
as they have a complex metric and gauge potential, they may be related to a
Wick rotated theory or to a theory where the coupling is taken to be imaginary.
These solutions thus provide a partial realization of true multi-center
black-holes in gauged supergravities.
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Instructors and researchers think "thinking like a physicist" is important
for students' professional development. However, precise definitions and
observational markers remain elusive. We reinterpret popular beliefs
inventories in physics to indicate what physicists think "thinking like a
physicist" entails. Through discourse analysis of upper-division students'
speech in natural settings, we show that students may appropriate or resist
these elements. We identify a new element in the physicist speech genre: brief,
embedded, spontaneous metacognitive talk (BESM talk). BESM talk communicates
students' in-the-moment enacted expectations about physics as a technical field
and a cultural endeavor. Students use BESM talk to position themselves as
physicists or non-physicists. Students also use BESM talk to communicate their
expectations in four ways: understanding, confusion, spotting inconsistencies,
and generalized expectations.
|
Convolutional neural networks (CNNs) have achieved significant popularity,
but their computational and memory intensity poses challenges for
resource-constrained computing systems, particularly with the prerequisite of
real-time performance. To release this burden, model compression has become an
important research focus. Many approaches like quantization, pruning, early
exit, and knowledge distillation have demonstrated the effect of reducing
redundancy in neural networks. Upon closer examination, it becomes apparent
that each approach capitalizes on its unique features to compress the neural
network, and they can also exhibit complementary behavior when combined. To
explore the interactions and reap the benefits from the complementary features,
we propose the Chain of Compression, which works on the combinational sequence
to apply these common techniques to compress the neural network. Validated on
the image-based regression and classification networks across different data
sets, our proposed Chain of Compression can significantly compress the
computation cost by 100-1000 times with ignorable accuracy loss compared with
the baseline model.
|
We describe the $C^*$-algebra of an $E$-unitary or strongly 0-$E$-unitary
inverse semigroup as the partial crossed product of a commutative $C^*$-algebra
by the maximal group image of the inverse semigroup. We give a similar result
for the $C^*$-algebra of the tight groupoid of an inverse semigroup. We also
study conditions on a groupoid $C^*$-algebra to be Morita equivalent to a full
crossed product of a commutative $C^*$-algebra with an inverse semigroup,
generalizing results of Khoshkam and Skandalis for crossed products with
groups.
|
We investigate the privacy of two approaches to (biometric) template
protection: Helper Data Systems and Sparse Ternary Coding with Ambiguization.
In particular, we focus on a privacy property that is often overlooked, namely
how much leakage exists about one specific binary property of one component of
the feature vector. This property is e.g. the sign or an indicator that a
threshold is exceeded.
We provide evidence that both approaches are able to protect such sensitive
binary variables, and discuss how system parameters need to be set.
|
We consider a recently proposed nonlinear Schroedinger equation exhibiting
soliton-like solutions of the power-law form $e_q^{i(kx-wt)}$, involving the
$q$-exponential function which naturally emerges within nonextensive
thermostatistics [$e_q^z \equiv [1+(1-q)z]^{1/(1-q)}$, with $e_1^z=e^z$]. Since
these basic solutions behave like free particles, obeying $p=\hbar k$, $E=\hbar
\omega$ and $E=p^2/2m$ ($1 \le q<2$), it is relevant to investigate how they
change under the effect of uniform acceleration, thus providing the first steps
towards the application of the aforementioned nonlinear equation to the study
of physical scenarios beyond free particle dynamics. We investigate first the
behaviour of the power-law solutions under Galilean transformation and discuss
the ensuing Doppler-like effects. We consider then constant acceleration,
obtaining new solutions that can be equivalently regarded as describing a free
particle viewed from an uniformly accelerated reference frame (with
acceleration $a$) or a particle moving under a constant force $-ma$. The latter
interpretation naturally leads to the evolution equation $i\hbar
\frac{\partial}{\partial t}(\frac{\Phi}{\Phi_0}) = -
\frac{1}{2-q}\frac{\hbar^2}{2m} \frac{\partial^2}{\partial x^2}
[(\frac{\Phi}{\Phi_0})^{2-q}] + V(x)(\frac{\Phi}{\Phi_0})^{q}$ with $V(x)=max$.
Remarkably enough, the potential $V$ couples to $\Phi^q$, instead of coupling
to $\Phi$, as happens in the familiar linear case ($q=1$).
|
In a paper by Sapounakis, Tasoulas, and Tsikouras \cite{stt}, the authors
count the number of occurrences of patterns of length four in Dyck paths. In
this paper we specify in one direction and generalize in another. We only count
ballot paths that avoid a given pattern, where a ballot path stays weakly above
the diagonal $y=x$, starts at the origin, and takes steps from the set
$\{\uparrow ,\to \}=\{u,r\}$. A pattern is a finite string made from the same
step set; it is also a path. Notice that a ballot path ending at a point along
the diagonal is a Dyck path.
|
It is argued that it is far more cost effective to carry out some projects
with medium-sized dedicated zenith telescopes rather than large steerable
telescopes, freeing the later to carry out projects that truly need them. I
show that the large number of objects observed with a surveying 4-m zenith
telescope allows one to carry out cosmological projects at low redshifts.
Examining two case studies, I show first that a variability survey would obtain
light curves for several thousands of type Ia supernovae per year up to z=1 and
easily discriminate among competing cosmological models. Finally, I discuss a
second case study, consisting of a spectrophotometric survey carried out with
interference filters, showing its power to discriminate among cosmological
models and to study the large-scale distribution of galaxies in the Universe.
|
A new approach to understanding evolution [Val09], namely viewing it through
the lens of computation, has already started yielding new insights, e.g.,
natural selection under sexual reproduction can be interpreted as the
Multiplicative Weight Update (MWU) Algorithm in coordination games played among
genes [CLPV14]. Using this machinery, we study the role of mutation in changing
environments in the presence of sexual reproduction. Following [WVA05], we
model changing environments via a Markov chain, with the states representing
environments, each with its own fitness matrix. In this setting, we show that
in the absence of mutation, the population goes extinct, but in the presence of
mutation, the population survives with positive probability. On the way to
proving the above theorem, we need to establish some facts about dynamics in
games. We provide the first, to our knowledge, polynomial convergence bound for
noisy MWU in a coordination game. Finally, we also show that in static
environments, sexual evolution with mutation converges, for any level of
mutation.
|
The mode-fluctuation distribution $P(W)$ is studied for chaotic as well as
for non-chaotic quantum billiards. This statistic is discussed in the broader
framework of the $E(k,L)$ functions being the probability of finding $k$ energy
levels in a randomly chosen interval of length $L$, and the distribution of
$n(L)$, where $n(L)$ is the number of levels in such an interval, and their
cumulants $c_k(L)$. It is demonstrated that the cumulants provide a possible
measure for the distinction between chaotic and non-chaotic systems. The
vanishing of the normalized cumulants $C_k$, $k\geq 3$, implies a Gaussian
behaviour of $P(W)$, which is realized in the case of chaotic systems, whereas
non-chaotic systems display non-vanishing values for these cumulants leading to
a non-Gaussian behaviour of $P(W)$. For some integrable systems there exist
rigorous proofs of the non-Gaussian behaviour which are also discussed. Our
numerical results and the rigorous results for integrable systems suggest that
a clear fingerprint of chaotic systems is provided by a Gaussian distribution
of the mode-fluctuation distribution $P(W)$.
|
Parallel acquisition systems arise in various applications in order to
moderate problems caused by insufficient measurements in single-sensor systems.
These systems allow simultaneous data acquisition in multiple sensors, thus
alleviating such problems by providing more overall measurements. In this work
we consider the combination of compressed sensing with parallel acquisition. We
establish the theoretical improvements of such systems by providing recovery
guarantees for which, subject to appropriate conditions, the number of
measurements required per sensor decreases linearly with the total number of
sensors. Throughout, we consider two different sampling scenarios -- distinct
(corresponding to independent sampling in each sensor) and identical
(corresponding to dependent sampling between sensors) -- and a general
mathematical framework that allows for a wide range of sensing matrices (e.g.,
subgaussian random matrices, subsampled isometries, random convolutions and
random Toeplitz matrices). We also consider not just the standard sparse signal
model, but also the so-called sparse in levels signal model. This model
includes both sparse and distributed signals and clustered sparse signals. As
our results show, optimal recovery guarantees for both distinct and identical
sampling are possible under much broader conditions on the so-called sensor
profile matrices (which characterize environmental conditions between a source
and the sensors) for the sparse in levels model than for the sparse model. To
verify our recovery guarantees we provide numerical results showing phase
transitions for a number of different multi-sensor environments.
|
We present 850 and 450 micron observations of the dense regions within the
Auriga-California molecular cloud using SCUBA-2 as part of the JCMT Gould Belt
Legacy Survey to identify candidate protostellar objects, measure the masses of
their circumstellar material (disk and envelope), and compare the star
formation to that in the Orion A molecular cloud. We identify 59 candidate
protostars based on the presence of compact submillimeter emission,
complementing these observations with existing Herschel/SPIRE maps. Of our
candidate protostars, 24 are associated with young stellar objects (YSOs) in
the Spitzer and Herschel/PACS catalogs of 166 and 60 YSOs, respectively (177
unique), confirming their protostellar nature. The remaining 35 candidate
protostars are in regions, particularly around LkHalpha 101, where the
background cloud emission is too bright to verify or rule out the presence of
the compact 70 micron emission that is expected for a protostellar source. We
keep these candidate protostars in our sample but note that they may indeed be
prestellar in nature. Our observations are sensitive to the high end of the
mass distribution in Auriga-Cal. We find that the disparity between the
richness of infrared star forming objects in Orion A and the sparsity in
Auriga-Cal extends to the submillimeter, suggesting that the relative star
formation rates have not varied over the Class II lifetime and that Auriga-Cal
will maintain a lower star formation efficiency.
|
I show that the characteristic diffusion timescale and the gamma-ray escape
timescale, of SN Ia supernova ejecta, are related with each other through the
time when the bolometric luminosity, $L_{\rm bol}$, intersects with
instantaneous radioactive decay luminosity, $L_\gamma$, for the second time
after the light-curve peak. Analytical arguments, numerical radiation-transport
calculations, and observational tests show that $L_{\rm bol}$ generally
intersects $L_\gamma$ at roughly $1.7$ times the characteristic diffusion
timescale of the ejecta. This relation implies that the gamma-ray escape
timescale is typically 2.7 times the diffusion timescale, and also implies that
the bolometric luminosity 15 days after the peak, $L_{\rm bol}(t_{15})$, must
be close to the instantaneous decay luminosity at that time, $L_\gamma
(t_{15})$. With the employed calculations and observations, the accuracy of
$L_{\rm bol}=L_\gamma$ at $t=t_{15}$ is found to be comparable to the simple
version of "Arnett's rule" ($L_{\rm bol}=L_\gamma$ at $t=t_{\rm peak}$). This
relation aids the interpretation of SN Ia supernova light curves and may also
be applicable to general hydrogen-free explosion scenarios powered by other
central engines.
|
Persuasion and argumentation are possibly among the most complex examples of
the interplay between multiple human subjects. With the advent of the Internet,
online forums provide wide platforms for people to share their opinions and
reasonings around various diverse topics. In this work, we attempt to model
persuasive interaction between users on Reddit, a popular online discussion
forum. We propose a deep LSTM model to classify whether a conversation leads to
a successful persuasion or not, and use this model to predict whether a certain
chain of arguments can lead to persuasion. While learning persuasion dynamics,
our model tends to identify argument facets implicitly, using an attention
mechanism. We also propose a semi-supervised approach to extract argumentative
components from discussion threads. Both these models provide useful insight
into how people engage in argumentation on online discussion forums.
|
Activity of inhibitory neuron with delayed feedback is considered in the
framework of point stochastic processes. The neuron receives excitatory input
impulses from a Poisson stream, and inhibitory impulses from the feedback line
with a delay. We investigate here, how does the presence of inhibitory feedback
affect the output firing statistics. Using binding neuron (BN) as a model, we
derive analytically the exact expressions for the output interspike intervals
(ISI) probability density, mean output ISI and coefficient of variation as
functions of model's parameters for the case of threshold 2. Using the leaky
integrate-and-fire (LIF) model, as well as the BN model with higher thresholds,
these statistical quantities are found numerically. In contrast to the
previously studied situation of no feedback, the ISI probability densities
found here both for BN and LIF neuron become bimodal and have discontinuity of
jump type. Nevertheless, the presence of inhibitory delayed feedback was not
found to affect substantially the output ISI coefficient of variation. The ISI
coefficient of variation found ranges between 0.5 and 1. It is concluded that
introduction of delayed inhibitory feedback can radically change neuronal
output firing statistics. This statistics is as well distinct from what was
found previously (Vidybida & Kravchuk, 2009) by a similar method for excitatory
neuron with delayed feedback.
|
The structural properties of Er-doped AlNO epilayers grown by radio frequency
magnetron sputtering were studied by Extended X-ray Absorption Fine Structure
(EXAFS) spectra recorded at the Er L 3 edge. The analysis revealed that Er
substitutes for Al in all the studied samples and the increase in Er
concentration from 0.5 to 3.6 at.% is not accompanied by formation of ErN, Er 2
O 3 or Er clusters. Simultaneously recorded X-ray Absorption Near Edge
Structure (XANES) spectra verify that the bonding configuration of Er is
similar in all studied samples. The Er-N distance is 2 constant at 2.18-2.19
{\AA} i.e. approximately 15% larger than the Al-N bondlength, revealing that
the introduction of Er in the cation sublattice causes considerable local
distortion. The Debye-Waller factor, which measures the static disorder, of the
second nearest shell of Al neighbors, has a local minimum for the sample
containing 1% Er that coincides with the highest photoluminescence efficiency
of the sample set.
|
We report initial measurements on our firstMoAu Transition Edge Sensors
(TESs). The TESs formed from a bilayer of 40 nm of Mo and 106 nm of Au showed
transition temperatures of about 320 mK, higher than identical TESs with a MoCu
bilayer which is consistent with a reduced electron transmission coefficient
between the bilayer films. We report measurements of thermal conductance in the
200 nm thick silicon nitride SiNx support structures at this temperature, TES
dynamic behaviour and current noise measurements.
|
We present a quantitative study of strain correlations in quiescent
supercooled liquids and glasses. Recent two-dimensional computer simulations
and experiments indicate that even supercooled liquids exhibit long-lived,
long-range strain correlations. Here we investigate this issue in three
dimensions via experiments on hard sphere colloids and molecular dynamics
simulations of a glass forming binary Lennard Jones mixture. Both in the glassy
state and in the supercooled regime, strain correlations are found to decay
with a $1/r^{3}$ power-law behavior, reminiscent of elastic fields around an
inclusion. Moreover, theoretical predictions on the time dependence of the
correlation amplitude are in line with the results obtained from experiments
and simulations. It is argued that the size of the domain, which exhibits a
"solid-like" cooperative strain pattern in a supercooled liquid, is determined
by the product of the speed of sound with the structural relaxation time. While
this length is of the order of nanometers in the normal liquid state, it grows
to macroscale when approaching the glass transition.
|
We present an analysis of a Suzaku observation of the link region between the
galaxy clusters A399 and A401. We obtained the metallicity of the intracluster
medium (ICM) up to the cluster virial radii for the first time. We determine
the metallicity where the virial radii of the two clusters cross each other (~2
Mpc away from their centers) and found that it is comparable to that in their
inner regions (~0.2 Zsun). It is unlikely that the uniformity of metallicity up
to the virial radii is due to mixing caused by a cluster collision. Since the
ram-pressure is too small to strip the interstellar medium of galaxies around
the virial radius of a cluster, the fairly high metallicity that we found there
indicates that the metals in the ICM are not transported from member galaxies
by ram-pressure stripping. Instead, the uniformity suggests that the
proto-cluster region was extensively polluted with metals by extremely powerful
outflows (superwinds) from galaxies before the clusters formed. We also
searched for the oxygen emission from the warm--hot intergalactic medium in
that region and obtained a strict upper limit of the hydrogen density
(nH<4.1x10^-5 cm^-3).
|
In this paper, we prove a necessary and sufficient condition for Tracy-Widom
law of Wigner matrices. Consider $N \times N$ symmetric Wigner matrices $H$
with $H_{ij} = N^{-1/2} x_{ij}$, whose upper right entries $x_{ij}$ $(1\le i<
j\le N)$ are $i.i.d.$ random variables with distribution $\mu$ and diagonal
entries $x_{ii}$ $(1\le i\le N)$ are $i.i.d.$ random variables with
distribution $\wt \mu$. The means of $\mu$ and $\wt \mu$ are zero, the variance
of $\mu$ is 1, and the variance of $\wt \mu $ is finite. We prove that
Tracy-Widom law holds if and only if $\lim_{s\to \infty}s^4\p(|x_{12}| \ge
s)=0$. The same criterion holds for Hermitian Wigner matrices.
|
Subsets and Splits
Filtered Text Samples
Retrieves 100 samples of text containing the specific phrase "You are a helpful assistant", providing limited insight into the dataset.
Helpful Assistant Text Samples
Returns a limited set of rows containing the phrase 'helpful assistant' in the text, providing basic filtering of relevant entries.