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arxiv_dataset-90001710.04617 | Planetary formation and water delivery in the habitable zone around
solar-type stars in different dynamical environments
astro-ph.EP
Aims. We study the formation and water delivery of planets in the habitable
zone (HZ) around solar-type stars. In particular, we study different dynamical
environments that are defined by the most massive body in the system. Methods.
First of all, a semi-analytical model was used to define the mass of the
protoplanetary disks that produce each of the five dynamical scenarios of our
research. Then, we made use of the same semi-analytical model to describe the
evolution of embryos and planetesimals during the gaseous phase. Finally, we
carried out N-body simulations of planetary accretion in order to analyze the
formation and water delivery of planets in the HZ in the different dynamical
environments. Results. Water worlds are efficiently formed in the HZ in
different dynamical scenarios. In systems with a giant planet analog to Jupiter
or Saturn around the snow line, super-Earths tend to migrate into the HZ from
outside the snow line as a result of interactions with other embryos and
accrete water only during the gaseous phase. In systems without giant planets,
Earths and super-Earths with high water by mass contents can either be formed
in situ in the HZ or migrate into it from outer regions, and water can be
accreted during the gaseous phase and in collisions with water-rich embryos and
planetesimals. Conclusions. The formation of planets in the HZ with very high
water by mass contents seems to be a common process around Sun- like stars. Our
research suggests that such planets are still very efficiently produced in
different dynamical environments. Moreover, our study indicates that the
formation of planets in the HZ with masses and water contents similar to those
of Earth seems to be a rare process around solar-type stars in the systems
under consideration.
| arxiv topic:astro-ph.EP |
arxiv_dataset-90011710.04717 | Generalised ballooning theory of two dimensional tokamak modes
physics.plasm-ph
In this work, using solutions from a local gyrokinetic flux-tube code
combined with higher order ballooning theory, a new analytical approach is
developed to reconstruct the global linear mode structure with associated
global mode frequency. In addition to the isolated mode (IM), which usually
peaks on the outboard mid-plane, the higher order ballooning theory has also
captured other types of less unstable global modes: (a) the weakly asymmetric
ballooning theory (WABT) predicts a mixed mode (MM) that undergoes a small
poloidal shift away from the outboard mid-plane, (b) a relatively more stable
general mode (GM) balloons on the top (or bottom) of the tokamak plasma. In
this paper, an analytic approach is developed to combine these disconnected
analytical limits into a single generalised ballooning theory (GBT). This is
used to investigate how an IM behaves under the effect of sheared toroidal
flow. For small values of flow an IM initially converts into a MM where the
results of WABT are recaptured, and eventually, as the flow increases, the mode
asymptotically becomes a GM on the top (or bottom) of the plasma. This may be
an ingredient in models for understanding why in some experimental scenarios,
instead of large edge localised modes (ELMs), small ELMs are observed. Finally,
our theory can have other important consequences, especially for calculations
involving Reynolds stress driven intrinsic rotation through the radial
asymmetry in the global mode structures. Understanding the intrinsic rotation
is significant because external torque in a plasma the size of ITER is expected
to be relatively low.
| arxiv topic:physics.plasm-ph |
arxiv_dataset-90021710.04817 | Ultimate precision of joint quadrature parameter estimation with a
Gaussian probe
quant-ph
The Holevo Cram\'er Rao bound is a lower bound on the sum of the mean square
error of estimates for parameters of a state. We provide a method for
calculating the Holevo Cram\'er-Rao bound for estimation of quadrature mean
parameters of a Gaussian state by formulating the problem as a semidefinite
program. In this case, the bound is tight; it is attained by purely Guassian
measurements. We consider the example of a symmetric two-mode squeezed thermal
state undergoing an unknown displacement on one mode. We calculate the Holevo
Cram\'er-Rao bound for joint estimation of the conjugate parameters for this
displacement. The optimal measurement is different depending on whether the
state is entangled or separable.
| arxiv topic:quant-ph |
arxiv_dataset-90031710.04917 | Statistics of the relative velocity of particles in turbulent flows :
monodisperse particles
physics.flu-dyn
We use direct numerical simulations to calculate the joint probability
density function of the relative distance $R$ and relative radial velocity
component $V_R$ for a pair of heavy inertial particles suspended in homogeneous
and isotropic turbulent flows. At small scales the distribution is scale
invariant, with a scaling exponent that is related to the particle-particle
correlation dimension in phase space, $D_2$. It was argued [1, 2] that the
scale invariant part of the distribution has two asymptotic regimes: (1) $|V_R|
\ll R$ where the distribution depends solely on $R$; and (2) $|V_R| \gg R$
where the distribution is a function of $|V_R|$ alone. The probability
distributions in these two regimes are matched along a straight line $|V_R| =
z^\ast R$. Our simulations confirm that this is indeed correct. We further
obtain $D_2$ and $z^\ast$ as a function of the Stokes number, ${\rm St}$. The
former depends non-monotonically on ${\rm St}$ with a minimum at about ${\rm
St} \approx 0.7$ and the latter has only a weak dependence on ${\rm St}$.
| arxiv topic:physics.flu-dyn |
arxiv_dataset-90041710.05017 | The power of sum-of-squares for detecting hidden structures
cs.DS cs.CC
We study planted problems---finding hidden structures in random noisy
inputs---through the lens of the sum-of-squares semidefinite programming
hierarchy (SoS). This family of powerful semidefinite programs has recently
yielded many new algorithms for planted problems, often achieving the best
known polynomial-time guarantees in terms of accuracy of recovered solutions
and robustness to noise. One theme in recent work is the design of spectral
algorithms which match the guarantees of SoS algorithms for planted problems.
Classical spectral algorithms are often unable to accomplish this: the twist in
these new spectral algorithms is the use of spectral structure of matrices
whose entries are low-degree polynomials of the input variables. We prove that
for a wide class of planted problems, including refuting random constraint
satisfaction problems, tensor and sparse PCA, densest-k-subgraph, community
detection in stochastic block models, planted clique, and others, eigenvalues
of degree-d matrix polynomials are as powerful as SoS semidefinite programs of
roughly degree d. For such problems it is therefore always possible to match
the guarantees of SoS without solving a large semidefinite program. Using
related ideas on SoS algorithms and low-degree matrix polynomials (and inspired
by recent work on SoS and the planted clique problem by Barak et al.), we prove
new nearly-tight SoS lower bounds for the tensor and sparse principal component
analysis problems. Our lower bounds for sparse principal component analysis are
the first to suggest that going beyond existing algorithms for this problem may
require sub-exponential time.
| arxiv topic:cs.DS cs.CC |
arxiv_dataset-90051710.05117 | Computing the maximum matching width is NP-hard
cs.DM
The maximum matching width is a graph width parameter that is defined on a
branch-decomposition over the vertex set of a graph. In this short paper, we
prove that the problem of computing the maximum matching width is NP-hard.
| arxiv topic:cs.DM |
arxiv_dataset-90061710.05217 | Modular inequalities for the maximal operator in variable Lebesgue
spaces
math.CA math.AP
A now classical result in the theory of variable Lebesgue spaces due to
Lerner [A. K. Lerner, On modular inequalities in variable $L^p$ spaces, Archiv
der Math. 85 (2005), no. 6, 538-543] is that a modular inequality for the
Hardy-Littlewood maximal function in $L^{p(\cdot)}(\mathbb{R}^n)$ holds if and
only if the exponent is constant. We generalize this result and give a new and
simpler proof. We then find necessary and sufficient conditions for the
validity of the weaker modular inequality \[ \int_\Omega Mf(x)^{p(x)}\,dx \
\leq c_1 \int_\Omega |f(x)|^{q(x)}\,dx + c_2, \] where $c_1,\,c_2$ are
non-negative constants and $\Omega$ is any measurable subset of $\mathbb{R}^n$.
As a corollary we get sufficient conditions for the modular inequality \[
\int_\Omega |Tf(x)|^{p(x)}\,dx \ \leq c_1 \int_\Omega |f(x)|^{q(x)}\,dx + c_2,
\] where $T$ is any operator that is bounded on $L^p(\Omega)$, $1<p<\infty$.
| arxiv topic:math.CA math.AP |
arxiv_dataset-90071710.05317 | The Removal Lemma for Tournaments
math.CO
Suppose one needs to change the direction of at least $\epsilon n^2$ edges of
an $n$-vertex tournament $T$, in order to make it $H$-free. A standard
application of the regularity method shows that in this case $T$ contains at
least $f^*_H(\epsilon)n^h$ copies of $H$, where $f^*_H$ is some tower-type
function. It has long been observed that many graph/digraph problems become
easier when assuming that the host graph is a tournament. It is thus natural to
ask if the removal lemma becomes easier if we assume that the digraph $G$ is a
tournament.
Our main result here is a precise characterization of the tournaments $H$ for
which $f^*_H(\epsilon)$ is polynomial in $\epsilon$, stating that such a bound
is attainable if and only if $H$'s vertex set can be partitioned into two sets,
each spanning an acyclic directed graph. The proof of this characterization
relies, among other things, on a novel application of a regularity lemma for
matrices due to Alon, Fischer and Newman, and on probabilistic variants of
Ruzsa-Szemer\'edi graphs.
We finally show that even when restricted to tournaments, deciding if $H$
satisfies the condition of our characterization is an NP-hard problem.
| arxiv topic:math.CO |
arxiv_dataset-90081710.05417 | Performance of the extreme-AO instrument VLT/SPHERE and dependence on
the atmospheric conditions
astro-ph.IM
SPHERE is the high-contrast exoplanet imager and spectrograph installed at
the Unit Telescope 3 of the Very Large Telescope. After more than two years of
regular operations, we analyse statistically the performance of the adaptive
optics system and its dependence on the atmospheric conditions above the
Paranal observatory, as measured by the suite of dedicated instruments which
are part of the Astronomical Site Monitor and as estimated by the SPHERE
real-time calculator. We also explain how this information can be used to
schedule the observations in order to yield the best data quality and to guide
the astronomer when processing his/her data.
| arxiv topic:astro-ph.IM |
arxiv_dataset-90091710.05517 | Anisotropies of Ultra-high Energy Cosmic Rays Dominated by a Single
Source in the Presence of Deflections
astro-ph.HE
This work presents a scenario of ultra-high energy cosmic ray source
distribution where a nearby source is solely responsible for the anisotropies
in arrival directions of cosmic rays while the rest of the sources contribute
only isotropically. An analytical approach focused on large-scale anisotropies,
which are influenced by deflections in a Kolmogorov-type turbulent magnetic
field, is employed to provide more general results. When the recent Pierre
Auger Observatory angular power spectrum above 8 EeV is used the restricted
model gives, under the assumption of the small angle approximation, a solution
where the RMS deflection with respect to the line of sight is $\alpha_{\rm rms}
= \left(50^{+11}_{-10}\right)^\circ$, while the relative flux from the single
source $\eta=0.03\pm 0.01$. Furthermore, the solution can be translated into
constraints on the source distance, luminosity, and extra-galactic magnetic
field strength. For Centaurus A and the Virgo cluster the required relation
between the coherence length and the RMS magnetic field strength is obtained: a
coherence length of $~\sim 100\,\mathrm{kpc}$ would imply the RMS field
strength around $1\,\mathrm{nG}$ for iron dominated and above $10\,\mathrm{nG}$
for proton dominated composition. We also performed trajectory simulations with
our publicly available code CRPropa to show that our analytical model can serve
as a good approximation as long as the deflections in cosmic magnetic fields
can be described as a random walk. The simulations showed that generally
structured fields tend to suppress large-scale anisotropies, especially the
dipole, compared to anisotropies at smaller scales described by higher
multipoles.
| arxiv topic:astro-ph.HE |
arxiv_dataset-90101710.05617 | On the anisotropy in the arrival directions of ultra-high-energy cosmic
rays
astro-ph.HE
We present results of elaborate four-dimensional simulations of the
propagation of ultra-high-energy cosmic rays (UHECR), which are based on a
realistic astrophysical scenario. The distribution of the arrival directions of
the UHECR is found to have a pronounced dipolar anisotropy and rather weak
higher-order contributions to the angular power spectrum. This finding agrees
well with the recent observation of a dipolar anisotropy for UHECR with arrival
energies above 8 EeV by the Pierre Auger Observatory and constitutes an
important prediction for other energy ranges and higher-order angular
contributions for which sufficient experimental data are not yet available.
Since our astrophysical scenario enables simulations that are completely
consistent with the available data, this scenario will be a very useful basis
for related future studies.
| arxiv topic:astro-ph.HE |
arxiv_dataset-90111710.05717 | Influence of $f(R)$ Models on the Existence of Anisotropic
Self-Gravitating Systems
gr-qc
This paper aims to explore some realistic configurations of anisotropic
spherical structures in the background of metric $f(R)$ gravity, where $R$ is
the Ricci scalar. The solutions obtained by Krori and Barua are used to examine
the nature of particular compact stars with three different modified gravity
models. The behavior of material variables is analyzed through plots and the
physical viability of compact stars is investigated through energy conditions.
We also discuss the behavior of different forces, equation of state parameter,
measure of anisotropy and Tolman-Oppenheimer-Volkoff equation in the modeling
of stellar structures. The comparison from our graphical representations may
provide evidences for the realistic and viable $f(R)$ gravity models at both
theoretical and astrophysical scale.
| arxiv topic:gr-qc |
arxiv_dataset-90121710.05817 | Densely Connected Convolutional Networks and Signal Quality Analysis to
Detect Atrial Fibrillation Using Short Single-Lead ECG Recordings
eess.SP cs.CV stat.ML
The development of new technology such as wearables that record high-quality
single channel ECG, provides an opportunity for ECG screening in a larger
population, especially for atrial fibrillation screening. The main goal of this
study is to develop an automatic classification algorithm for normal sinus
rhythm (NSR), atrial fibrillation (AF), other rhythms (O), and noise from a
single channel short ECG segment (9-60 seconds). For this purpose, signal
quality index (SQI) along with dense convolutional neural networks was used.
Two convolutional neural network (CNN) models (main model that accepts 15
seconds ECG and secondary model that processes 9 seconds shorter ECG) were
trained using the training data set. If the recording is determined to be of
low quality by SQI, it is immediately classified as noisy. Otherwise, it is
transformed to a time-frequency representation and classified with the CNN as
NSR, AF, O, or noise. At the final step, a feature-based post-processing
algorithm classifies the rhythm as either NSR or O in case the CNN model's
discrimination between the two is indeterminate. The best result achieved at
the official phase of the PhysioNet/CinC challenge on the blind test set was
0.80 (F1 for NSR, AF, and O were 0.90, 0.80, and 0.70, respectively).
| arxiv topic:eess.SP cs.CV stat.ML |
arxiv_dataset-90131710.05917 | Resource Usage Analysis from a Different Perspective on MOOC Dropout
cs.CY
We present a novel learning analytics approach, for analyzing the usage of
resources in MOOCs. Our target stakeholders are the course designers who aim to
evaluate their learning materials. In order to gain insight into the way
educational resources are used, we view dropout behaviour in an atypical
manner: Instead of using it as an indicator of failure, we use it as a mean to
compute other features. For this purpose, we developed a prototype, called
RUAF, that can be applied to the data format provided by FutureLearn. As a
proof of concept, we perform a study by applying this tool to the interaction
data of learners from four MOOCs. We also study the quality of our
computations, by comparing them to existing process mining approaches. We
present results that highlight patterns showing how learners use resources. We
also show examples of practical conclusions a course designer may benefit from.
| arxiv topic:cs.CY |
arxiv_dataset-90141710.06017 | Metabolic enrichment through functional gene rules
q-bio.CB
It is well known that tumors originating from the same tissue have different
prognosis and sensitivity to treatments. Over the last decade, cancer genomics
consortia like the Cancer Genome Atlas (TCGA) have been generating thousands of
cross-sectional data, for thousands of human primary tumors originated from
various tissues. Thanks to that public database, it is today possible to
analyze a broad range of relevant information such as gene sequences,
expression profiles or metabolite footprints, to capture tumor molecular
heterogeneity and improve patient stratification and clinical management. To
this aim, it is common practice to analyze datasets grouped into clusters based
on clinical observations and/or molecular features. However, the identification
of specific properties of each cluster that may be effectively targeted by
therapeutic drugs still represents a challenging task. We define a method to
generate an activity score for the metabolic reactions of different clusters of
patients based on their transcriptional profile. This approach reduces the
number of variables from many genes to few reactions, by aggregating
transcriptional information associated to the same enzymatic reaction according
to gene-enzyme and enzyme-reaction rules. We also applied the methodology to a
dataset of 244 RNAseq transcriptional profiles taken from patients with
colorectal cancer (CRC). CRC samples are typically divided into two sub-types:
(i) tumors with microsatellite instability (MSI), associated with
hyper-mutation and with CpG island methylation phenotype, and (ii)
microsatellite stable (MSS) tumors, typically endowed with chromosomal
instability. We report some key differences in the central carbon metabolism of
the two clusters. We also show how the method can be used to describe the
metabolism of individual patients and cluster them exclusively based on
metabolic features.
| arxiv topic:q-bio.CB |
arxiv_dataset-90151710.06117 | Map-based Multi-Policy Reinforcement Learning: Enhancing Adaptability of
Robots by Deep Reinforcement Learning
cs.RO cs.AI cs.LG
In order for robots to perform mission-critical tasks, it is essential that
they are able to quickly adapt to changes in their environment as well as to
injuries and or other bodily changes. Deep reinforcement learning has been
shown to be successful in training robot control policies for operation in
complex environments. However, existing methods typically employ only a single
policy. This can limit the adaptability since a large environmental
modification might require a completely different behavior compared to the
learning environment. To solve this problem, we propose Map-based Multi-Policy
Reinforcement Learning (MMPRL), which aims to search and store multiple
policies that encode different behavioral features while maximizing the
expected reward in advance of the environment change. Thanks to these policies,
which are stored into a multi-dimensional discrete map according to its
behavioral feature, adaptation can be performed within reasonable time without
retraining the robot. An appropriate pre-trained policy from the map can be
recalled using Bayesian optimization. Our experiments show that MMPRL enables
robots to quickly adapt to large changes without requiring any prior knowledge
on the type of injuries that could occur. A highlight of the learned behaviors
can be found here: https://youtu.be/QwInbilXNOE .
| arxiv topic:cs.RO cs.AI cs.LG |
arxiv_dataset-90161710.06217 | Laurent positivity of quantized canonical bases for quantum cluster
varieties from surfaces
math.GT hep-th math-ph math.MP math.QA
In 2006, Fock and Goncharov constructed a nice basis of the ring of regular
functions on the moduli space of framed ${\rm PGL}_2$-local systems on a
punctured surface $S$. The moduli space is birational to a cluster
$\mathcal{X}$-variety, whose positive real points recover the enhanced
Teichm\"uller space of $S$. Their basis is enumerated by integral laminations
on $S$, which are collections of closed curves in $S$ with integer weights.
Around ten years later, a quantized version of this basis, still enumerated by
integral laminations, was constructed by Allegretti and Kim. For each choice of
an ideal triangulation of $S$, each quantum basis element is a Laurent
polynomial in the exponential of quantum shear coordinates for edges of the
triangulation, with coefficients being Laurent polynomials in $q$ with integer
coefficients. We show that these coefficients are Laurent polynomials in $q$
with positive integer coefficients. Our result was expected in a positivity
conjecture for framed protected spin characters in physics and provides a
rigorous proof of it, and may also lead to other positivity results, as well as
categorification. A key step in our proof is to solve a purely topological and
combinatorial ordering problem about an ideal triangulation and a closed curve
on $S$. For this problem we introduce a certain graph on $S$, which is
interesting in its own right.
| arxiv topic:math.GT hep-th math-ph math.MP math.QA |
arxiv_dataset-90171710.06317 | Bouncing and emergent cosmologies from ADM RG flows
gr-qc hep-th
The Asymptotically Safe Gravity provides a framework for the description of
gravity from the trans-Planckian regime to cosmological scales. According to
this scenario, the cosmological constant and Newton's coupling are functions of
the energy scale whose evolution is dictated by the renormalization group
equations. The formulation of the renormalization group equations on foliated
spacetimes, based on the Arnowitt-Deser-Misner (ADM) formalism, furnishes a
natural way to construct the RG energy scale from the spectrum of the laplacian
operator on the spatial slices. Combining this idea with a Renormalization
Group improvement procedure, in this work we study quantum gravitational
corrections to the Einstein-Hilbert action on
Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) backgrounds. The resulting
quantum-corrected Friedmann equations can give rise to both bouncing
cosmologies and emergent universe solutions. Our bouncing models do not require
the presence of exotic matter and emergent universe solutions can be
constructed for any allowed topology of the spatial slices.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-90181710.06417 | Jets in a strongly coupled anisotropic plasma
hep-th
In this paper, we study the dynamics of the light quark jet moving through
the static, strongly coupled $\mathcal{N}=4$, anisotropic plasma with and
without charge. The light quark is presented by a point-like initial condition
falling string in the context of the AdS/CFT. We calculate the stopping
distance of the light quark in the anisotropic medium and compare it with its
isotropic value. By studying the falling string in the beam direction and
transverse direction, we find that the jet quenching increases in both
directions. Although, the enhancement of quenching is larger in the beam
direction. Also, the suppression of stopping distance is more prominent when
the anisotropic plasma have the same temperature as the isotropic plasma.
| arxiv topic:hep-th |
arxiv_dataset-90191710.06517 | Dihedral Sieving Phenomena
math.CO math.RT
Cyclic sieving is a well-known phenomenon where certain interesting
polynomials, especially $q$-analogues, have useful interpretations related to
actions and representations of the cyclic group. We propose a definition of
sieving for an arbitrary group $G$ and study it for the dihedral group $I_2(n)$
of order $2n$. This requires understanding the generators of the representation
ring of the dihedral group. For $n$ odd, we exhibit several instances of
dihedral sieving which involve the generalized Fibonomial coefficients,
recently studied by Amdeberhan, Chen, Moll, and Sagan. We also exhibit an
instance of dihedral sieving involving Garsia and Haiman's $(q,t)$-Catalan
numbers.
| arxiv topic:math.CO math.RT |
arxiv_dataset-90201710.06617 | The Robust Reading Competition Annotation and Evaluation Platform
cs.CV
The ICDAR Robust Reading Competition (RRC), initiated in 2003 and
re-established in 2011, has become a de-facto evaluation standard for robust
reading systems and algorithms. Concurrent with its second incarnation in 2011,
a continuous effort started to develop an on-line framework to facilitate the
hosting and management of competitions. This paper outlines the Robust Reading
Competition Annotation and Evaluation Platform, the backbone of the
competitions. The RRC Annotation and Evaluation Platform is a modular
framework, fully accessible through on-line interfaces. It comprises a
collection of tools and services for managing all processes involved with
defining and evaluating a research task, from dataset definition to annotation
management, evaluation specification and results analysis. Although the
framework has been designed with robust reading research in mind, many of the
provided tools are generic by design. All aspects of the RRC Annotation and
Evaluation Framework are available for research use.
| arxiv topic:cs.CV |
arxiv_dataset-90211710.06717 | Vignetting effect in Fourier ptychographic microscopy
physics.optics
Fourier ptychographic microscopy (FPM) is a computational imaging technique
that overcomes the physical space-bandwidth product (SBP) limit of a
conventional microscope by applying angular diversity illuminations. In the
usual model of FPM, the microscopic system is approximated by being taken as
space-invariant with transfer function determined by a complex pupil function
of the objective. However, in real experimental conditions, several unexpected
"semi-bright and semi-dark" images with strong vignetting effect can be easily
observed when the sample is illuminated by the LED within the "transition zone"
between bright field and dark field. These imperfect images, apparently, are
not coincident with the space-invariant model and could deteriorate the
reconstruction quality severely. In this Letter, we examine the impact of this
space-invariant approximation on FPM image formation based on ray-based and
rigorous wave optics-based analysis. Our analysis shows that for a practical
FPM microscope with a low power objective and a large field of view, the space
invariance is destroyed by diffraction at other stops associated with different
lens elements to a large extent. A modified version of the space-variant model
is derived and discussed. Two simple countermeasures are also presented and
experimentally verified to bypass or partially alleviate the vignetting-induced
reconstruction artifacts.
| arxiv topic:physics.optics |
arxiv_dataset-90221710.06817 | Using MRI Cell Tracking to Monitor Immune Cell Recruitment in Response
to a Peptide-Based Cancer Vaccine
physics.med-ph q-bio.TO
Purpose: MRI cell tracking can be used to monitor immune cells involved in
the immunotherapy response, providing insight into the mechanism of action,
temporal progression of tumour growth and individual potency of therapies. To
evaluate whether MRI could be used to track immune cell populations in response
to immunotherapy, CD8+ cytotoxic T cells (CTLs), CD4+CD25+FoxP3+ regulatory T
cells (Tregs) and myeloid derived suppressor cells (MDSCs) were labelled with
superparamagnetic iron oxide (SPIO) particles.
Methods: SPIO-labelled cells were injected into mice (one cell type/mouse)
implanted with an HPV-based cervical cancer model. Half of these mice were also
vaccinated with DepoVaxTM, a lipid-based vaccine platform that was developed to
enhance the potency of peptide-based vaccines.
Results: MRI visualization of CTLs, Tregs and MDSCs was apparent 24 hours
post-injection, with hypointensities due to iron labelled cells clearing
approximately 72 hours post-injection. Vaccination resulted in increased
recruitment of CTLs and decreased recruitment of MDSCs and Tregs to the tumour.
We also found that MDSC and Treg recruitment was positively correlated with
final tumour volume.
Conclusion: This type of analysis can be used to non-invasively study changes
in immune cell recruitment in individual mice over time, potentially allowing
improved application and combination of immunotherapies.
| arxiv topic:physics.med-ph q-bio.TO |
arxiv_dataset-90231710.06917 | Annotating High-Level Structures of Short Stories and Personal Anecdotes
cs.CL
Stories are a vital form of communication in human culture; they are employed
daily to persuade, to elicit sympathy, or to convey a message. Computational
understanding of human narratives, especially high-level narrative structures,
remain limited to date. Multiple literary theories for narrative structures
exist, but operationalization of the theories has remained a challenge. We
developed an annotation scheme by consolidating and extending existing
narratological theories, including Labov and Waletsky's (1967) functional
categorization scheme and Freytag's (1863) pyramid of dramatic tension, and
present 360 annotated short stories collected from online sources. In the
future, this research will support an approach that enables systems to
intelligently sustain complex communications with humans.
| arxiv topic:cs.CL |
arxiv_dataset-90241710.07017 | Robust output regulation of 2 x 2 hyperbolic systems part I: Control law
and Input-to-State Stability
math.AP
We consider the problem of output feedback regulationfor a linear first-order
hyperbolic system with collocatedinput and output in presence of a general
class of disturbancesand noise. The proposed control law is designed through
abackstepping approach incorporating an integral action. Toensure robustness to
delays, the controller only cancels partof the boundary reflection by means of
a tunable parameter.This also enables a trade-off between disturbance and
noisesensitivity.We show that the boundary condition of the obtainedtarget
system can be transformed into a Neutral DifferentialEquation (NDE) and that
this latter system is Input-to-StateStable (ISS). This proves the boundedness
of the controlledoutput for the target system. This extends previous
worksconsidering an integral action for this kind of system [16],
andconstitutes an important step towards practical implementationof such
controllers. Applications and practical considerations,in particular regarding
the system's sensitivity functions arederived in a companion paper.
| arxiv topic:math.AP |
arxiv_dataset-90251710.07117 | The Graphical User Interface of the Operator of the Cherenkov Telescope
Array
astro-ph.IM
The Cherenkov Telescope Array (CTA) is the next generation gamma-ray
observatory. CTA will incorporate about 100 imaging atmospheric Cherenkov
telescopes (IACTs) at a southern site, and about 20 in the north. Previous IACT
experiments have used up to five telescopes. Subsequently, the design of a
graphical user interface (GUI) for the operator of CTA poses an interesting
challenge. In order to create an effective interface, the CTA team is
collaborating with experts from the field of Human-Computer Interaction. We
present here our GUI prototype. The back-end of the prototype is a Python Web
server. It is integrated with the observation execution system of CTA, which is
based on the Alma Common Software (ACS). The back-end incorporates a redis
database, which facilitates synchronization of GUI panels. redis is also used
to buffer information collected from various software components and databases.
The front-end of the prototype is based on Web technology. Communication
between Web server and clients is performed using Web Sockets, where graphics
are generated with the d3.js Javascript library.
| arxiv topic:astro-ph.IM |
arxiv_dataset-90261710.07217 | On the first curve of Fu\v{c}ik Spectrum Of $p$-fractional Laplacian
Operator with nonlocal normal boundary conditions
math.AP
In this article, we study the Fu\v{c}ik spectrum of the $p$-fractional
Laplace operator with nonlocal normal derivative conditions which is defined as
the set of all $(a,b)\in \mb R^2$ such that $$ \mc (F_p)\left\{
\begin{array}{lr} \Lambda_{n,p}(1-\al)(-\Delta)_{p}^{\al} u + |u|^{p-2}u =
\frac{\chi_{\Omega_\e}}{\e} (a (u^{+})^{p-1} - b (u^{-})^{p-1}) \;\quad
\text{in}\; \Omega,\quad \\ \mc{N}_{\al,p} u = 0 \; \quad \mbox{in}\; \mb R^n
\setminus \overline{\Omega}, \end{array} \right. $$ has a non-trivial solution
$u$, where $\Omega$ is a bounded domain in $\mb R^n$ with Lipschitz boundary,
$p \geq 2$, $n>p \al $, $\e, \al \in(0,1)$ and $\Omega{_\e}:=\{x \in \Omega:
d(x,\pa \Omega)\leq \e \}$. We showed existence of the first non-trivial curve
$\mc C$ of this spectrum which is used to obtain the variational
characterization of a second eigenvalue of the problem $\mc (F_p)$. We also
discuss some properties of this curve $\mc C$, e.g. Lipschitz continuous,
strictly decreasing and asymptotic behaviour and nonresonance with respect to
the Fu\v{c}ik spectrum.
| arxiv topic:math.AP |
arxiv_dataset-90271710.07317 | Two diverging length scales in the structure of jammed packings
cond-mat.soft
At densities higher than the jamming transition for athermal, frictionless
repulsive spheres we find two distinct length scales, both of which diverge as
a power law as the transition is approached. The first, $\xi_{Z}$, is
associated with the two-point correlation function for the number of contacts
on two particles as a function of the particle separation. The second,
$\xi_{f}$, is associated with contact-number fluctuations in subsystems of
different sizes. On scales below $\xi_{f}$ the fluctuations are highly
suppressed, similar to the phenomenon of hyperuniformity usually associated
with density fluctuations. The exponents for the divergence of $\xi_{Z}$ and
$\xi_{f}$ are different and appear to be different in two and three dimensions.
| arxiv topic:cond-mat.soft |
arxiv_dataset-90281710.07417 | On the Initial Algebra and Final Co-algebra of some Endofunctors on
Categories of Pointed Metric Spaces
math.CT
We consider two endofunctors of the form $~F:X\longrightarrow M\otimes X~$,
where $~M~$ is a non degenerate module, related to the unit interval and the
Sierpinski gasket, and their final co-algebras. The functors are defined on the
categories of bi-pointed and tri-pointed metric spaces, with continuous maps,
short maps or Lipschitz maps as the choice of morphisms.
First we demonstrate that the final co-algebra for these endofunctors on the
respective category of pointed metric spaces with the choice of continuous maps
is the final co-algebra of that with short maps and after forgetting the metric
structure is of that in the set setting. We use the fact that the final
co-algebra can be obtained by a Cauchy completion process, to construct the
mediating morphism from a co-algebra by means of the limit of a sequence
obtained by iterating the co-algebra. We also show that the Sierpinski gasket
$~(\mathbb{S},\sigma)~$ is not the final co-algebra for these endofunctors when
the morphism are restricted to being Lipschitz maps.
| arxiv topic:math.CT |
arxiv_dataset-90291710.07517 | Selfinjective algebras without short cycles of indecomposable modules
math.RT
We describe the structure of finite dimensional selfinjective algebras over
an arbitrary field without short cycles of indecomposable modules.
| arxiv topic:math.RT |
arxiv_dataset-90301710.07617 | Asymptotically Optimal Resource Block Allocation With Limited Feedback
cs.IT math.IT
Consider a channel allocation problem over a frequency-selective
channel.There are K channels (frequency bands) and N users such that K=bN for
some positive integer b. We want to allocate b channels (or resource blocks) to
each user. Due to the nature of the frequency-selective channel, each user
considers some channels to be better than others. The optimal solution to this
resource allocation problem can be computed using the Hungarian algorithm.
However, this requires knowledge of the numerical value of all the channel
gains, which makes this approach impractical for large networks. We suggest a
suboptimal approach, that only requires knowing what the M-best channels of
each user are. We find the minimal value of M such that there exists an
allocation where all the b channels each user gets are among his M-best. This
leads to feedback of significantly less than one bit per user per channel. For
a large class of fading distributions, including Rayleigh, Rician, m-Nakagami
and others, this suboptimal approach leads to both an asymptotically (in K)
optimal sum-rate and an asymptotically optimal minimal rate. Our
non-opportunistic approach achieves (asymptotically) full multiuser diversity
as well as optimal fairness, by contrast to all other limited feedback
algorithms.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-90311710.07717 | Magnetic field amplification in supernova remnants
astro-ph.HE
Based on the new findings on the turbulent dynamo in \citet{XL16}, we examine
the magnetic field amplification in the context of supernova remnants. Due to
the strong ion-neutral collisional damping in the weakly-ionized interstellar
medium, the dynamo in the preshock turbulence remains in the damping kinematic
regime, which leads to {\it a linear-in-time growth of the magnetic field
strength}. The resultant magnetic field structure enables effective diffusion
upstream and shock acceleration of cosmic rays to energies above the "knee".
Differently, the nonlinear dynamo in the postshock turbulence leads to {\it a
linear-in-time growth of the magnetic energy} due to the turbulent magnetic
diffusion. Given a weak initial field strength in the postshock region, the
magnetic field saturates at a significant distance from the shock front as a
result of the inefficiency of the nonlinear dynamo. This result is in a good
agreement with existing numerical simulations and well explains the X-ray spots
detected far behind the shock front.
| arxiv topic:astro-ph.HE |
arxiv_dataset-90321710.07817 | Cell-Free and User-Centric Massive MIMO at Millimeter Wave Frequencies
cs.IT math.IT
In a cell-free (CF) massive MIMO architecture a very large number of
distributed access points (APs) simultaneously and jointly serves a much
smaller number of mobile stations (MSs); a variant of the cell-free technique
is the user-centric (UC) approach, wherein each AP just decodes a reduced set
of MSs, practically the ones that are received best. This paper introduces and
analyzes the CF and UC architectures at millimeter wave (mmWave) frequencies.
First of all, a multiuser clustered channel model is introduced in order to
account for the correlation among the channels of nearby users; then, an uplink
multiuser channel estimation scheme is described along with low-complexity
hybrid analog/digital beamforming architectures. Interestingly, in the proposed
scheme no channel estimation is needed at the MSs, and the beamforming schemes
used at the MSs are channel-independent and have a very simple structure.
Numerical results show that the considered architectures provide good
performance, especially in lightly loaded systems, with the UC approach
outperforming the CF one.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-90331710.07917 | On nondiagonal finite quasi-qantum groups over finite abelian groups
math.QA
In this paper, we initiate the study of nondiagonal finite quasi-quantum
groups over finite abelian groups. We mainly study the Nichols algebras in the
twisted Yetter-Drinfeld module category $_{\k G}^{\k G}\mathcal{YD}^\Phi$ with
$\Phi$ a nonabelian $3$-cocycle on a finite abelian group $G.$ A complete
clarification is obtained for the Nichols algebra $B(V)$ in case $V$ is a
simple twisted Yetter-Drinfeld module of nondiagonal type. This is also applied
to provide a complete classification of finite-dimensional coradically graded
pointed coquasi-Hopf algebras over abelian groups of odd order and confirm
partially the generation conjecture of pointed finite tensor categories due to
Etingof, Gelaki, Nikshych and Ostrik.
| arxiv topic:math.QA |
arxiv_dataset-90341710.08017 | Adaptive Bayesian nonparametric regression using kernel mixture of
polynomials with application to partial linear model
math.ST stat.TH
We propose a kernel mixture of polynomials prior for Bayesian nonparametric
regression. The regression function is modeled by local averages of polynomials
with kernel mixture weights. We obtain the minimax-optimal rate of contraction
of the full posterior distribution up to a logarithmic factor that adapts to
the smoothness level of the true function by estimating metric entropies of
certain function classes. We also provide a frequentist sieve maximum
likelihood estimator with a near-optimal convergence rate. We further
investigate the application of the kernel mixture of polynomials to the partial
linear model and obtain both the near-optimal rate of contraction for the
nonparametric component and the Bernstein-von Mises limit (i.e., asymptotic
normality) of the parametric component. The proposed method is illustrated with
numerical examples and shows superior performance in terms of computational
efficiency, accuracy, and uncertainty quantification compared to the local
polynomial regression, DiceKriging, and the robust Gaussian stochastic process.
| arxiv topic:math.ST stat.TH |
arxiv_dataset-90351710.08117 | Electrically tunable exchange splitting in bilayer graphene on monolayer
Cr$_2$X$_2$Te$_6$ with X=Ge, Si, and Sn
cond-mat.mes-hall
We investigate the electronic band structure and the proximity exchange
effect in bilayer graphene on a family of ferromagnetic multilayers
Cr$_2$X$_2$Te$_6$, X=Ge, Si, and Sn, with first principles methods. In each
case the intrinsic electric field of the heterostructure induces an orbital gap
on the order of 10 meV in the graphene bilayer. The proximity exchange is
strongly band dependent. For example, in the case of Cr$_2$Ge$_2$Te$_6$, the
low-energy valence band of bilayer graphene has exchange splitting of 8 meV,
while the low energy conduction band's splitting is 30 times less (0.3 meV).
This striking discrepancy stems from the layer-dependent hybridization with the
ferromagnetic substrate. Remarkably, applying a vertical electric field of a
few V/nm reverses the exchange, allowing us to effectively turn ON and OFF
proximity magnetism in bilayer graphene. Such a field-effect should be generic
for van der Waals bilayers on ferromagnetic insulators, opening new
possibilities for spin-based devices.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-90361710.08217 | Democratizing online controlled experiments at Booking.com
cs.HC
There is an extensive literature about online controlled experiments, both on
the statistical methods available to analyze experiment results as well as on
the infrastructure built by several large scale Internet companies but also on
the organizational challenges of embracing online experiments to inform product
development. At Booking.com we have been conducting evidenced based product
development using online experiments for more than ten years. Our methods and
infrastructure were designed from their inception to reflect Booking.com
culture, that is, with democratization and decentralization of experimentation
and decision making in mind.
In this paper we explain how building a central repository of successes and
failures to allow for knowledge sharing, having a generic and extensible code
library which enforces a loose coupling between experimentation and business
logic, monitoring closely and transparently the quality and the reliability of
the data gathering pipelines to build trust in the experimentation
infrastructure, and putting in place safeguards to enable anyone to have end to
end ownership of their experiments have allowed such a large organization as
Booking.com to truly and successfully democratize experimentation.
| arxiv topic:cs.HC |
arxiv_dataset-90371710.08317 | Mask Responses for Single-Pixel Terahertz Imaging
physics.optics
Terahertz (THz) radiation meaning electromagnetic radiation in the range from
0.1 THz (3 mm) to 10 THz (30 mu) has the unique advantage of easily penetrating
many obstructions while being non-hazardous to organic tissue since it is
non-ionizing. A shortcoming of this domain is the limited availability of
high-sensitivity detector arrays respective THz cameras with >1k pixels. To
overcome the imaging limitations of the THz domain, compressive imaging in
combination with an optically controllable THz spatial light modulator is a
promising approach especially when used in a single-pixel imaging modality. The
imaging fidelity, performance and speed of this approach depend crucially on
the imaging patterns also called masks and their properties used in the imaging
process. Therefore, in this paper, it is investigated how the image quality
after reconstruction is specifically influenced by the different mask types and
their properties in a compressive imaging modality. The evaluation derives
specific guidelines for the use in THz single-pixel imaging setups respective
THz single-pixel cameras employing optically controllable THz spatial light
modulators. As an outlook, a method is suggested that builds upon the results
presented in this text and extends the discussed advantages to an improved
compressive imaging setting fit for stand-off security imaging applications aka
single-pixel detector Body Scanners.
| arxiv topic:physics.optics |
arxiv_dataset-90381710.08417 | The dependence of convective core overshooting on stellar mass:
semi-empirical determination using the diffusive approach with two different
element mixtures
astro-ph.SR
Convective core overshooting has a strong influence on the evolution of stars
of moderate and high mass. Studies of double-lined eclipsing binaries and
stellar oscillations have renewed interest in the possible dependence of
overshooting on stellar mass, which has been poorly constrained by observations
so far. Here we have used a sample of 29 well-studied double-lined eclipsing
binaries in key locations of the H-R diagram to establish the explicit
dependence of f(ov) on mass, where f(ov) is the free parameter in the diffusive
approximation to overshooting. Measurements of the masses, radii, and
temperatures of the binary components were compared against stellar evolution
calculations based on the MESA code to infer semi-empirical values of f(ov) for
each component. We find a clear mass dependence such that f(ov) rises sharply
from zero in the range 1.2--2.0 solar masses, and levels off thereafter up to
the 4.4 solar mass limit of our sample. Tests with two different element
mixtures indicate the trend is the same, and we find it is also qualitatively
similar to the one established in our previous study with the classical
step-function implementation of overshooting characterized by the free
parameter alpha(ov). Based on these measurements we infer an approximate
relationship between the two overshooting parameters of alpha(ov)/f(ov) = 11.36
+/- 0.22, with a possible dependence on stellar properties.
| arxiv topic:astro-ph.SR |
arxiv_dataset-90391710.08517 | Distribution of coherence in multipartite systems under entropic
coherence measure
quant-ph math-ph math.MP
The distribution of coherence in multipartite systems is one of the
fundamental problems in the resource theory of coherence. To quantify the
coherence in multipartite systems more precisely, we introduce new coherence
measures, incoherent-quantum (IQ) coherence measures, on bipartite systems by
the max- and min- relative entropies and provide the operational interpretation
in certain subchannel discrimination problem. By introducing the smooth max-
and min- relative entropies of incoherent-quantum (IQ) coherence on bipartite
systems, we exhibit the distribution of coherence in multipartite systems: the
total coherence is lower bounded by the sum of local coherence and genuine
multipartite entanglement. Besides, we find the monogamy relationship for
coherence on multipartite systems by incoherent-quantum (IQ) coherence
measures. Thus, the IQ coherence measures introduced here truly capture the
non-sharability of quantumness of coherence in multipartite context.
| arxiv topic:quant-ph math-ph math.MP |
arxiv_dataset-90401710.08617 | Electronic structure of Pr2MnNiO6 from x-ray photoemission, absorption
and density functional theory
cond-mat.str-el
The electronic structure of double perovskite Pr2MnNiO6 is studied using core
x-ray photoelectron spectroscopy and x-ray absorption spectroscopy. The 2p
x-ray absorption spectra show that Mn and Ni are in 2+ and 4+ states
respectively. Using charge transfer multiplet analysis of Ni and Mn 2p XPS
spectra, we find charge transfer energies {\Delta} of 3.5 and 2.5 eV for Ni and
Mn respectively. The ground state of Ni2+ and Mn4+ reveal a higher d electron
count of 8.21 and 3.38 respectively as compared to the atomic values of 8.00
and 3.00 respectively thereby indicating the covalent nature of the system. The
O 1s edge absorption spectra reveal a band gap of 0.9 eV which is comparable to
the value obtained from first principle calculations for U-J >= 2 eV. The
density of states clearly reveal a strong p-d type charge transfer character of
the system, with band gap proportional to average charge transfer energy of
Ni2+ and Mn4+ ions.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-90411710.08717 | Auto-Differentiating Linear Algebra
cs.MS cs.LG stat.ML
Development systems for deep learning (DL), such as Theano, Torch,
TensorFlow, or MXNet, are easy-to-use tools for creating complex neural network
models. Since gradient computations are automatically baked in, and execution
is mapped to high performance hardware, these models can be trained end-to-end
on large amounts of data. However, it is currently not easy to implement many
basic machine learning primitives in these systems (such as Gaussian processes,
least squares estimation, principal components analysis, Kalman smoothing),
mainly because they lack efficient support of linear algebra primitives as
differentiable operators. We detail how a number of matrix decompositions
(Cholesky, LQ, symmetric eigen) can be implemented as differentiable operators.
We have implemented these primitives in MXNet, running on CPU and GPU in single
and double precision. We sketch use cases of these new operators, learning
Gaussian process and Bayesian linear regression models, where we demonstrate
very substantial reductions in implementation complexity and running time
compared to previous codes. Our MXNet extension allows end-to-end learning of
hybrid models, which combine deep neural networks (DNNs) with Bayesian
concepts, with applications in advanced Gaussian process models, scalable
Bayesian optimization, and Bayesian active learning.
| arxiv topic:cs.MS cs.LG stat.ML |
arxiv_dataset-90421710.08817 | A tilted pulse-front setup for femtosecond extreme ultraviolet transient
grating spectroscopy in highly non-collinear geometries
physics.ins-det physics.optics
We demonstrate a tilted pulse-front transient grating technique that allows
to optimally utilize time-resolution as well as transient grating line density
while probing under grazing incidence as typically done in extreme ultraviolet
(EUV) or soft x-ray (SXR) experiments. Our optical setup adapts the pulse front
tilt of the two pulses that create the transient grating to the relative tilt
grazing incident pulse. We demonstrate the technique using all 800 nm
femtosecond laser pulses for transient grating generation on a vanadium dioxide
film. We probe that grating via diffraction of a third 800 nm pulse. The time
resolution of 100 fs is an improvement by a factor 30 compared to our previous
experiments on the same system (1,2). The scheme paves the way for EUV and SXR
probing of optically induced transient gratings on any material.
| arxiv topic:physics.ins-det physics.optics |
arxiv_dataset-90431710.08917 | Van der Waals Materials for Atomically-Thin Photovoltaics: Promise and
Outlook
physics.optics cond-mat.mes-hall physics.app-ph
Two-dimensional (2D) semiconductors provide a unique opportunity for
optoelectronics due to their layered atomic structure, electronic and optical
properties. To date, a majority of the application-oriented research in this
field has been focused on field-effect electronics as well as photodetectors
and light emitting diodes. Here we present a perspective on the use of 2D
semiconductors for photovoltaic applications. We discuss photonic device
designs that enable light trapping in nanometer-thickness absorber layers, and
we also outline schemes for efficient carrier transport and collection. We
further provide theoretical estimates of efficiency indicating that 2D
semiconductors can indeed be competitive with and complementary to conventional
photovoltaics, based on favorable energy bandgap, absorption, external
radiative efficiency, along with recent experimental demonstrations. Photonic
and electronic design of 2D semiconductor photovoltaics represents a new
direction for realizing ultrathin, efficient solar cells with applications
ranging from conventional power generation to portable and ultralight solar
power.
| arxiv topic:physics.optics cond-mat.mes-hall physics.app-ph |
arxiv_dataset-90441710.09017 | Hard X-ray Quiescent Emission in Magnetars via Resonant Compton
Upscattering
astro-ph.HE
Non-thermal quiescent X-ray emission extending between 10 keV and around 150
keV has been seen in about 10 magnetars by RXTE, INTEGRAL, Suzaku, NuSTAR and
Fermi-GBM. For inner magnetospheric models of such hard X-ray signals, inverse
Compton scattering is anticipated to be the most efficient process for
generating the continuum radiation, because the scattering cross section is
resonant at the cyclotron frequency. We present hard X-ray upscattering spectra
for uncooled monoenergetic relativistic electrons injected in inner regions of
pulsar magnetospheres. These model spectra are integrated over bundles of
closed field lines and obtained for different observing perspectives. The
spectral turnover energies are critically dependent on the observer viewing
angles and electron Lorentz factor. We find that electrons with energies less
than around 15 MeV will emit most of their radiation below 250 keV, consistent
with the turnovers inferred in magnetar hard X-ray tails. Electrons of higher
energy still emit most of the radiation below around 1 MeV, except for
quasi-equatorial emission locales for select pulse phases. Our spectral
computations use a new state-of-the-art, spin-dependent formalism for the QED
Compton scattering cross section in strong magnetic fields.
| arxiv topic:astro-ph.HE |
arxiv_dataset-90451710.09117 | BAT AGN Spectroscopic Survey--VIII. Type 1 AGN With Massive Absorbing
Columns
astro-ph.GA
We explore the relationship between X-ray absorption and optical obscuration
within the BAT AGN Spectroscopic Survey (BASS) which has been collecting and
analyzing the optical and X-ray spectra for 641 hard X-ray selected ($E>14$
keV) active galactic nuclei (AGN). We use the deviation from a linear broad
H$\alpha$-to-X-ray relationship as an estimate of the maximum optical
obscuration towards the broad line region and compare the $A_{\rm V}$ to the
hydrogen column densities ($N_{\rm H}$) found through systematic modeling of
their X-ray spectra. We find that the inferred columns implied by $A_{\rm V}$
towards the broad line region (BLR) are often orders of magnitude less than the
columns measured towards the X-ray emitting region indicating a small scale
origin for the X-ray absorbing gas. After removing 30\% of Sy 1.9s that
potentially have been misclassified due to outflows, we find that 86\%
(164/190) of the Type 1 population (Sy 1--1.9) are X-ray unabsorbed as expected
based on a single obscuring structure. However, 14\% (26/190), of which 70\%
(18/26) are classified as Sy 1.9, are X-ray absorbed, suggesting the broad line
region itself is providing extra obscuration towards the X-ray corona. The
fraction of X-ray absorbed Type 1 AGN remains relatively constant with AGN
luminosity and Eddington ratio, indicating a stable broad line region covering
fraction.
| arxiv topic:astro-ph.GA |
arxiv_dataset-90461710.09217 | Unramified 2-extensions of totally imaginary number fields and 2-adic
analytic groups
math.NT
- Let K be a totally imaginary number field. Denote by G ur K (2) the Galois
group of the maximal unramified pro-2 extension of K. By comparing cup-products
in {\'e}tale cohomology of SpecO K and cohomology of uniform pro-2 groups, we
obtain situations where G ur K (2) has no non-trivial uniform analytic
quotient, proving some new special cases of the unramified Fontaine-Mazur
conjecture. For example, in the family of imaginary quadratic fields K for
which the 2-rank of the class group is equal to 5, we obtain that for at least
33.12% of such K, the group G ur K (2) has no non-trivial uniform analytic
quotient.
| arxiv topic:math.NT |
arxiv_dataset-90471710.09317 | LOOP Descriptor: Local Optimal Oriented Pattern
cs.CV
This letter introduces the LOOP binary descriptor (local optimal oriented
pattern) that encodes rotation invariance into the main formulation itself.
This makes any post processing stage for rotation invariance redundant and
improves on both accuracy and time complexity. We consider fine-grained
lepidoptera (moth/butterfly) species recognition as the representative problem
since it involves repetition of localized patterns and textures that may be
exploited for discrimination. We evaluate the performance of LOOP against its
predecessors as well as few other popular descriptors. Besides experiments on
standard benchmarks, we also introduce a new small image dataset on NZ
Lepidoptera. Loop performs as well or better on all datasets evaluated compared
to previous binary descriptors. The new dataset and demo code of the proposed
method are to be made available through the lead author's academic webpage and
GitHub.
| arxiv topic:cs.CV |
arxiv_dataset-90481710.09417 | Cross-identification of stellar catalogs with multiple stars: Complexity
and Resolution
cs.DM astro-ph.IM cs.CC
In this work, I present an optimization problem which consists of assigning
entries of a stellar catalog to multiple entries of another stellar catalog
such that the probability of such assignment is maximum. I show a way of
modeling it as a Maximum Weighted Stable Set Problem which is further used to
solve a real astronomical instance and I partially characterize the forbidden
subgraphs of the resulting family of graphs given by that reduction. Finally, I
prove that the problem is NP-Hard.
| arxiv topic:cs.DM astro-ph.IM cs.CC |
arxiv_dataset-90491710.09517 | CODA: Enabling Co-location of Computation and Data for Near-Data
Processing
cs.AR
Recent studies have demonstrated that near-data processing (NDP) is an
effective technique for improving performance and energy efficiency of
data-intensive workloads. However, leveraging NDP in realistic systems with
multiple memory modules introduces a new challenge. In today's systems, where
no computation occurs in memory modules, the physical address space is
interleaved at a fine granularity among all memory modules to help improve the
utilization of processor-memory interfaces by distributing the memory traffic.
However, this is at odds with efficient use of NDP, which requires careful
placement of data in memory modules such that near-data computations and their
exclusively used data can be localized in individual memory modules, while
distributing shared data among memory modules to reduce hotspots. In order to
address this new challenge, we propose a set of techniques that (1) enable
collections of OS pages to either be fine-grain interleaved among memory
modules (as is done today) or to be placed contiguously on individual memory
modules (as is desirable for NDP private data), and (2) decide whether to
localize or distribute each memory object based on its anticipated access
pattern and steer computations to the memory where the data they access is
located. Our evaluations across a wide range of workloads show that the
proposed mechanism improves performance by 31% and reduces 38% remote data
accesses over a baseline system that cannot exploit computate-data affinity
characteristics.
| arxiv topic:cs.AR |
arxiv_dataset-90501710.09617 | Streaming Small-Footprint Keyword Spotting using Sequence-to-Sequence
Models
cs.CL
We develop streaming keyword spotting systems using a recurrent neural
network transducer (RNN-T) model: an all-neural, end-to-end trained,
sequence-to-sequence model which jointly learns acoustic and language model
components. Our models are trained to predict either phonemes or graphemes as
subword units, thus allowing us to detect arbitrary keyword phrases, without
any out-of-vocabulary words. In order to adapt the models to the requirements
of keyword spotting, we propose a novel technique which biases the RNN-T system
towards a specific keyword of interest.
Our systems are compared against a strong sequence-trained, connectionist
temporal classification (CTC) based "keyword-filler" baseline, which is
augmented with a separate phoneme language model. Overall, our RNN-T system
with the proposed biasing technique significantly improves performance over the
baseline system.
| arxiv topic:cs.CL |
arxiv_dataset-90511710.09717 | The KP approximation under a weak Coriolis forcing
math.AP
In this paper, we study the asymptotic behavior of weakly transverse
water-waves under a weak Coriolis forcing in the long wave regime. We derive
the Boussinesq-Coriolis equations in this setting and we provide a rigorous
justification of this model. Then, from these equations, we derive two other
asymptotic models. When the Coriolis forcing is weak, we fully justify the
rotation-modified Kadomtsev-Petviashvili equation (also called
Grimshaw-Melville equation). When the Coriolis forcing is very weak, we
rigorously justify the Kadomtsev-Petviashvili equation. This work provides the
first mathematical justification of the KP approximation under a Coriolis
forcing.
| arxiv topic:math.AP |
arxiv_dataset-90521710.09817 | $\overline{B}\rightarrow D^\ast\ell\overline{\nu}$ at non-zero recoil
hep-lat
We present preliminary results from our analysis of the form factors for the
$\overline{B}\rightarrow D^\ast\ell\overline{\nu}$ decay at non-zero recoil.
Our analysis includes 15 MILC asqtad ensembles with $N_f=2+1$ flavors of sea
quarks and lattice spacings ranging from $a\approx 0.15$ fm down to $0.045$ fm.
The valence light quarks employ the asqtad action, whereas the heavy quarks are
treated using the Fermilab action. We conclude with a discussion of future
plans and phenomenological implications. When combined with experimental
measurements of the decay rate, our calculation will enable a determination of
the CKM matrix element $|V_{cb}|$.
| arxiv topic:hep-lat |
arxiv_dataset-90531710.09917 | A De Giorgi Iteration-based Approach for the Establishment of ISS
Properties of a Class of Semi-linear Parabolic PDEs with Boundary and
In-domain Disturbances
math.OC
This paper addresses input-to-state stability (ISS) properties with respect
to boundary and in-domain disturbances for a class of semi-linear partial
differential equations (PDEs) subject to Dirichlet boundary conditions. The
developed approach is a combination of the method of De Giorgi iteration and
the technique of Lyapunov functionals by adequately splitting the original
problem into two subsystems. The ISS in $L^\infty$-norm for a 1-$D$ transport
equation and the ISS in $L^2$-norm for Burgers' equation have been established
using this method. As an application of the main result for the 1-D transport
equation, a study on ISS properties in $L^\infty$-norm of a 1-D transport
equation with anti-stable term under boundary feedback control is carried out.
This is the first time that the method of De Giorgi iteration is introduced in
the ISS theory for infinite dimensional systems, and the developed method can
be generalized for tackling some problems on multidimensional spatial domains
and be applied to a wider class of nonlinear parabolic PDEs.
| arxiv topic:math.OC |
arxiv_dataset-90541710.10017 | Theory overview of tree-level $B$ decays
hep-ph hep-ex
I describe the theoretical progress in the study of semileptonic tree-level B
decays, and its interplay with recent experimental results. In particular, I
focus on two anomalies: the ratios $R(D^{(*)})=\displaystyle\frac{{\cal B}(B
\to D^{(*)} \tau \bar \nu_\tau)}{{\cal B}(B \to D^{(*)} \ell \bar \nu_\ell)}$
and the inclusive versus exclusive determination of $|V_{cb}|$. I review a few
explanations proposed for such anomalies, and discuss tests to shed light on
their origin.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-90551710.10117 | Reality-Aware Social Choice
cs.CY cs.GT cs.MA
Social Choice theory generalizes voting on one proposal to ranking multiple
proposals. Yet, while a vote on a single proposal has the status quo (Reality)
as a default, Reality has been forsaken during this generalization. Here, we
propose to restore this default social state and to incorporate Reality
explicitly into Social Choice. We show that doing so gives rise to a new
theory, complete with its domain restrictions, voting rules with their
Reality-aware axiomatic properties, and certain game-theoretic aspects. In
particular, we show how Reality can be used in a principled way to break
Condorcet cycles and develop an efficient Reality-aware Condorcet-consistent
agenda. We then discuss several applications of Reality-Aware Social Choice.
| arxiv topic:cs.CY cs.GT cs.MA |
arxiv_dataset-90561710.10217 | Fronthaul-Aware Software-Defined Wireless Networks: Resource Allocation
and User Scheduling
cs.NI
Software-defined networking (SDN) provides an agile and programmable way to
optimize radio access networks via a control-data plane separation.
Nevertheless, reaping the benefits of wireless SDN hinges on making optimal use
of the limited wireless fronthaul capacity. In this work, the problem of
fronthaul-aware resource allocation and user scheduling is studied. To this
end, a two-timescale fronthaul-aware SDN control mechanism is proposed in which
the controller maximizes the time-averaged network throughput by enforcing a
coarse correlated equilibrium in the long timescale. Subsequently, leveraging
the controller's recommendations, each base station schedules its users using
Lyapunov stochastic optimization in the short timescale, i.e., at each time
slot. Simulation results show that significant network throughput enhancements
and up to 40% latency reduction are achieved with the aid of the SDN
controller. Moreover, the gains are more pronounced for denser network
deployments.
| arxiv topic:cs.NI |
arxiv_dataset-90571710.10317 | The saturation bifurcation in coupled oscillators
nlin.PS
We examine examples of weakly nonlinear systems whose steady states undergo a
bifurcation with increasing forcing, such that a forced subsystem abruptly
ceases to absorb additional energy, instead diverting it into an initially
quiescent, unforced subsystem. We derive and numerically verify analytical
predictions for the existence and behavior of such saturated states for a class
of oscillator pairs. We also examine related phenomena, including
zero-frequency response to periodic forcing, Hopf bifurcations to
quasiperiodicity, and bifurcations to periodic behavior with multiple
frequencies.
| arxiv topic:nlin.PS |
arxiv_dataset-90581710.10417 | Correction to the article: Floer homology and splicing knot complements
math.GT
This note corrects the mistakes in the splicing formulas of the paper "Floer
homology and splicing knot complements". The mistakes are the result of the
incorrect assumption that for a knot $K$ inside a homology sphere $Y$, the
involution on the knot Floer homology of $K$ which corresponds to moving the
basepoints by one full twist around $K$ is trivial. The correction implicitly
involves considering the contribution from this (possibly non-trivial)
involution in a number of places.
| arxiv topic:math.GT |
arxiv_dataset-90591710.10517 | The asymptotic properties of $\phi(n)$ and a problem related to
visibility of Lattice points
math.NT
We look at the average sum of the Euler's phi function $\phi{(n)}$ and it's
relation with the visibility of a point from the origin.We show that
$\forall{\hspace{0.05in}{k} \ge{1}},k\in\mathbb{N},\exists$ a $k$$\times$$k$
grid in the 2D space such that no point inside it is visible from the origin.We
define visibility of a lattice point from a set and try to find a bound for the
cardinality of the smallest set S such that for a given $n$ $\in\mathbb{N}$,all
points from the $n$$\times$$n$ grid are visible from S.
| arxiv topic:math.NT |
arxiv_dataset-90601710.10617 | Natural SUSY at LHC with Right-Sneutrino LSP
hep-ph
We study an extension of the minimal supersymmetric standard model (MSSM)
with additional right-handed singlet neutrino superfields. While such an
extension incorporates a mechanism for the neutrino mass, it also opens up the
possibility of having the right-sneutrinos ($\widetilde{\nu}$) as the lightest
supersymmetric particle (LSP). In this work, we focus on the the viability of
rather small ($\lesssim 500$ GeV) higgsino mass parameter ($\mu$), an important
ingredient for "naturalness", in the presence of such a LSP. For simplicity, we
assume that the bino and wino mass parameters are much heavier, thus we only
consider (almost) pure and compressed higgsino-like states, with small
$\mathcal{O}(10^{-2})$ gaugino admixture. Considering only prompt decays of the
higgino-like states, especially the lightest chargino, we discuss the
importance of leptonic channels consisting of up to two leptons with large
missing transverse energy to probe this scenario at the Large Hadron Collider
(LHC). Further, we emphasize on how the gaugino mass parameters, although very
heavy, affects the decay of the low-lying higgsino-like states, thus
significantly affecting the proposed signatures at LHC.
| arxiv topic:hep-ph |
arxiv_dataset-90611710.10717 | Experimental Realization of Quantum Violation of Entropic Noncontextual
Inequality in Four Dimension Using IBM Quantum Computer
quant-ph
In quantum information theory, entropic inequalities act as the necessary and
sufficient conditions to noncontextuality. Here, we first experimentally
demonstrate the violation of the entropic noncontextual inequality in a
four-level quantum system, by using the five-qubit IBM quantum computer. The
experimental result disproves the existence of a local realist model.
| arxiv topic:quant-ph |
arxiv_dataset-90621710.10817 | An experimental study of the rearrangements of valence protons and
neutrons amongst single-particle orbits during double {\beta} decay in 100Mo
nucl-ex
The rearrangements of protons and neutrons amongst the valence
single-particle orbitals during double {\beta} decay of 100Mo have been
determined by measuring cross sections in (d,p), (p,d), (3He,{\alpha}) and
(3He,d) reactions on 98,100Mo and 100,102Ru targets. The deduced nucleon
occupancies reveal significant discrepancies when compared with theoretical
calculations; the same calculations have previously been used to determine the
nuclear matrix element associated with the decay probability of double {\beta}
decay of the 100Mo system.
| arxiv topic:nucl-ex |
arxiv_dataset-90631710.10917 | Diffraction-induced entanglement loss of orbital-angular-momentum states
quant-ph
We provide an analytical expression for the entanglement decay of initially
maximally entangled orbital angular momentum bi-photon states, when scattered
off an obstruction. We show that the decay is controlled by the
diffraction-induced mutual overlap between the diffracted field modes, and
quantify its dependence on the size and position of the obstruction.
| arxiv topic:quant-ph |
arxiv_dataset-90641710.11017 | Synergy in the Knowledge Base of U.S. Innovation Systems at National,
State, and Regional Levels: The Contributions of High-Tech Manufacturing and
Knowledge-Intensive Services
cs.DL cs.CY
Using information theory, we measure innovation systemness as synergy among
size-classes, zip-codes, and technological classes (NACE-codes) for 8.5 million
American companies. The synergy at the national level is decomposed at the
level of states, Core-Based Statistical Areas (CBSA), and Combined Statistical
Areas (CSA). We zoom in to the state of California and in more detail to
Silicon Valley. Our results do not support the assumption of a national system
of innovations in the U.S.A. Innovation systems appear to operate at the level
of the states; the CBSA are too small, so that systemness spills across their
borders. Decomposition of the sample in terms of high-tech manufacturing (HTM),
medium-high-tech manufacturing (MHTM), knowledge-intensive services (KIS), and
high-tech services (HTKIS) does not change this pattern, but refines it. The
East Coast -- New Jersey, Boston, and New York -- and California are the major
players, with Texas a third one in the case of HTKIS. Chicago and industrial
centers in the Midwest also contribute synergy. Within California, Los Angeles
contributes synergy in the sectors of manufacturing, the San Francisco area in
KIS. Knowledge-intensive services in Silicon Valley and the Bay area -- a CSA
composed of seven CBSA -- spill over to other regions and even globally.
| arxiv topic:cs.DL cs.CY |
arxiv_dataset-90651710.11117 | Measuring molecular abundances in comet C/2014 Q2 (Lovejoy) using the
APEX telescope
astro-ph.EP
Comet composition provides critical information on the chemical and physical
processes that took place during the formation of the Solar system. We report
here on millimetre spectroscopic observations of the long-period bright comet
C/2014 Q2 (Lovejoy) using the Atacama Pathfinder Experiment (APEX) band 1
receiver between 2015 January UT 16.948 to 18.120, when the comet was at
heliocentric distance of 1.30 AU and geocentric distance of 0.53 AU. Bright
comets allow for sensitive observations of gaseous volatiles that sublimate in
their coma. These observations allowed us to detect HCN, CH3OH (multiple
transitions), H2CO and CO, and to measure precise molecular production rates.
Additionally, sensitive upper limits were derived on the complex molecules
acetaldehyde (CH3CHO) and formamide (NH2CHO) based on the average of the
strongest lines in the targeted spectral range to improve the signal-to-noise
ratio. Gas production rates are derived using a non-LTE molecular excitation
calculation involving collisions with H2O and radiative pumping that becomes
important in the outer coma due to solar radiation. We find a depletion of CO
in C/2014 Q2 (Lovejoy) with a production rate relative to water of 2 per cent,
and relatively low abundances of Q(HCN)/Q(H2O), 0.1 per cent, and
Q(H2CO)/Q(H2O), 0.2 per cent. In contrast the CH3OH relative abundance
Q(CH3OH)/Q(H2O), 2.2 per cent, is close to the mean value observed in other
comets. The measured production rates are consistent with values derived for
this object from other facilities at similar wavelengths taking into account
the difference in the fields of view. Based on the observed mixing ratios of
organic molecules in four bright comets including C/2014 Q2, we find some
support for atom addition reactions on cold dust being the origin of some of
the molecules.
| arxiv topic:astro-ph.EP |
arxiv_dataset-90661710.11217 | Location-adjusted Wald statistics for scalar parameters
stat.ME
Inference about a scalar parameter of interest is a core statistical task
that has attracted immense research in statistics. The Wald statistic is a
prime candidate for the task, on the grounds of the asymptotic validity of the
standard normal approximation to its finite-sample distribution, simplicity and
low computational cost. It is well known, though, that this normal
approximation can be inadequate, especially when the sample size is small or
moderate relative to the number of parameters. A novel, algebraic adjustment to
the Wald statistic is proposed, delivering significant improvements in
inferential performance with only small implementation and computational
overhead, predominantly due to additional matrix multiplications. The Wald
statistic is viewed as an estimate of a transformation of the model parameters
and is appropriately adjusted, using either maximum likelihood or reduced-bias
estimators, bringing its expectation asymptotically closer to zero. The
location adjustment depends on the expected information, an approximation to
the bias of the estimator, and the derivatives of the transformation, which are
all either readily available or easily obtainable in standard software for a
wealth of models. An algorithm for the implementation of the location-adjusted
Wald statistics in general models is provided, as well as a bootstrap scheme
for the further scale correction of the location-adjusted statistic. Ample
analytical and numerical evidence is presented for the adoption of the
location-adjusted statistic in prominent modelling settings, including
inference about log-odds and binomial proportions, logistic regression in the
presence of nuisance parameters, beta regression, and gamma regression. The
location-adjusted Wald statistics are used for the construction of significance
maps for the analysis of multiple sclerosis lesions from MRI data.
| arxiv topic:stat.ME |
arxiv_dataset-90671710.11317 | Nebula: F0 Estimation and Voicing Detection by Modeling the Statistical
Properties of Feature Extractors
eess.AS cs.SD
A F0 and voicing status estimation algorithm for high quality speech
analysis/synthesis is proposed. This problem is approached from a different
perspective that models the behavior of feature extractors under noise, instead
of directly modeling speech signals. Under time-frequency locality assumptions,
the joint distribution of extracted features and target F0 can be characterized
by training a bank of Gaussian mixture models (GMM) on artificial data
generated from Monte-Carlo simulations. The trained GMMs can then be used to
generate a set of conditional distributions on the predicted F0, which are then
combined and post-processed by Viterbi algorithm to give a final F0 trajectory.
Evaluation on CSTR and CMU Arctic speech databases shows that the proposed
method, trained on fully synthetic data, achieves lower gross error rates than
state-of-the-art methods.
| arxiv topic:eess.AS cs.SD |
arxiv_dataset-90681710.11417 | TreeQN and ATreeC: Differentiable Tree-Structured Models for Deep
Reinforcement Learning
cs.AI cs.LG cs.NE stat.ML
Combining deep model-free reinforcement learning with on-line planning is a
promising approach to building on the successes of deep RL. On-line planning
with look-ahead trees has proven successful in environments where transition
models are known a priori. However, in complex environments where transition
models need to be learned from data, the deficiencies of learned models have
limited their utility for planning. To address these challenges, we propose
TreeQN, a differentiable, recursive, tree-structured model that serves as a
drop-in replacement for any value function network in deep RL with discrete
actions. TreeQN dynamically constructs a tree by recursively applying a
transition model in a learned abstract state space and then aggregating
predicted rewards and state-values using a tree backup to estimate Q-values. We
also propose ATreeC, an actor-critic variant that augments TreeQN with a
softmax layer to form a stochastic policy network. Both approaches are trained
end-to-end, such that the learned model is optimised for its actual use in the
tree. We show that TreeQN and ATreeC outperform n-step DQN and A2C on a
box-pushing task, as well as n-step DQN and value prediction networks (Oh et
al. 2017) on multiple Atari games. Furthermore, we present ablation studies
that demonstrate the effect of different auxiliary losses on learning
transition models.
| arxiv topic:cs.AI cs.LG cs.NE stat.ML |
arxiv_dataset-90691710.11517 | Calculations of low-frequency radio emission by cosmic ray-induced
particle showers
astro-ph.HE
The radio technique for the detection of high energy cosmic rays consists in
measuring the electric field created by the particle showers created inside a
medium by the primary cosmic ray. The electric field is then used to infer the
properties of the primary particle. Nowadays, the radio technique is a
standard, well-established technique. While most current experiments measure
the field at frequencies above $20$ MHz, several experiments have reported a
large emission at low frequencies, below $10$ MHz. The EXTASIS experiment aims
at measuring again and understand this low-frequency electric field. Since at
low frequencies the standard far-field approximation for the calculation of the
electric field does not necessarily hold, in order to comprehend the
low-frequency emission we need to go beyond the far-field approximation. We
present in this work a formula for the electric field created by a particle
track inside a dielectric medium that is valid for all frequencies. We then
implement this formula in the SELFAS Monte Carlo code and calculate the
low-frequency electric field of EAS. We also introduce the sudden death pulse
(SDP), an emission caused by the coherent deceleration of the shower front, and
study its properties.
| arxiv topic:astro-ph.HE |
arxiv_dataset-90701710.11617 | Stable subgroups and Morse subgroups in mapping class groups
math.GT math.GR
For a finitely generated group, there are two recent generalizations of the
notion of a quasiconvex subgroup of a word-hyperbolic group, namely a stable
subgroup and a Morse or strongly quasiconvex subgroup. Durham and Taylor
defined stability and proved stability is equivalent to convex cocompactness in
mapping class groups. Another natural generalization of quasiconvexity is given
by the notion of a Morse or strongly quasiconvex subgroup of a finitely
generated group, studied recently by Tran and Genevois. In general, a subgroup
is stable if and only if the subgroup is Morse and hyperbolic. In this paper,
we prove that two properties of being Morse and stable coincide for a subgroup
of infinite index in the mapping class group of an oriented, connected, finite
type surface with negative Euler characteristic.
| arxiv topic:math.GT math.GR |
arxiv_dataset-90711711.0009 | An optical metamixer
physics.optics cond-mat.mtrl-sci
A frequency mixer is a nonlinear device that combines electromagnetic waves
to create waves at new frequencies. Mixers are ubiquitous components in modern
radio-frequency technology and are widely used in microwave signal processing.
The development of versatile frequency mixers for optical frequencies remains
challenging: such devices generally rely on weak nonlinear optical processes
and, thus, must satisfy phase matching conditions. In this work, we utilize a
GaAs-based dielectric metasurface to demonstrate an optical frequency mixer
that concurrently generates eleven new frequencies spanning the ultraviolet to
near-infrared (NIR) spectral range. Our approach combines strong intrinsic
material nonlinearities, enhanced electromagnetic fields, and relaxed
phase-matching requirements, to allow seven different nonlinear optical
processes to occur simultaneously. Specifically, when pumped by two femtosecond
NIR pulses, we observe second-, third- and fourth-harmonic generation,
sum-frequency generation, two-photon absorption induced photoluminescence,
four-wave mixing, and six-wave mixing. Such ultracompact optical mixers may
enable a plethora of applications in biology, chemistry, sensing,
communications and quantum optics.
| arxiv topic:physics.optics cond-mat.mtrl-sci |
arxiv_dataset-90721711.0019 | Two-loop binding corrections to the electron gyromagnetic factor
physics.atom-ph
We compute corrections to the gyromagnetic factor of an electron bound in a
hydrogen-like ion at order alpha^2(Z alpha)^5. This result removes a major
uncertainty in predictions for silicon and carbon ions, used to determine the
atomic mass of the electron.
| arxiv topic:physics.atom-ph |
arxiv_dataset-90731711.0029 | Uniqueness theorem for static phantom wormholes in
Einstein-Maxwell-dilaton theory
gr-qc hep-th
We prove a uniqueness theorem for traversable wormhole solutions in the
Einstein-Maxwell-dilaton gravity with a phantom scalar field and a possible
phantom electromagnetic field. In a certain region of the parameter space,
determined by the asymptotic values of the scalar field and the lapse function,
the regular wormholes are completely specified by their mass, scalar charge and
electric charge. The argument is based on the positive energy theorem applied
on an appropriate conformally transformed Riemannian space.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-90741711.0039 | AGT relations for sheaves on surfaces
math.AG math-ph math.MP math.RT
We consider a natural generalization of the Carlsson-Okounkov Ext operator on
the K-theory groups of the moduli spaces of stable sheaves on a smooth
projective surface. We compute the commutation relations between the Ext
operator and the action of the deformed W-algebra on K-theory, which was
developed in [18]. The conclusion is that the Ext operator is closely related
with a vertex operator, thus giving a mathematical incarnation of the
Alday-Gaiotto-Tachikawa correspondence for a general algebraic surface.
| arxiv topic:math.AG math-ph math.MP math.RT |
arxiv_dataset-90751711.0049 | Julia Robinson numbers and arithmetical dynamic of quadratic polynomials
math.NT
For rings $\mathcal{O}_K$ of totally real algebraic integers, J. Robinson
defined a set which is always $\{+\infty\}$ or of the form $[\lambda,+\infty)$
or $(\lambda,+\infty)$ for some real number $\lambda\ge4$. All known examples
give either $\{+\infty\}$ or $[4,+\infty)$. In this paper, we construct
infinitely many fields such that the set is an interval, but not equal to
$[4,+\infty)$.
| arxiv topic:math.NT |
arxiv_dataset-90761711.0059 | Ultimate position resolution of pixel clusters with binary readout for
particle tracking
physics.ins-det
Silicon tracking detectors can record the charge in each channel (analog or
digitized) or have only binary readout (hit or no hit). While there is
significant literature on the position resolution obtained from interpolation
of charge measurements, a comprehensive study of the resolution obtainable with
binary readout is lacking. It is commonly assumed that the binary resolution is
$\text{pitch}/\sqrt{12}$, but this is generally a worst case upper limit. In
this paper we study, using simulation, the best achievable resolution for
minimum ionizing particles in binary readout pixels. A wide range of incident
angles and pixel sizes are simulated with a standalone code, using the Bichsel
model for charge deposition. The results show how the resolution depends on
angles and sensor geometry. Until the pixel pitch becomes so small as to be
comparable to the distance between energy deposits in silicon, the resolution
is always better, and in some cases much better, than $\text{pitch}/\sqrt{12}$.
| arxiv topic:physics.ins-det |
arxiv_dataset-90771711.0069 | Long-Lasting Extreme Magnetic Storm Activities in 1770 Found in
Historical Documents
astro-ph.SR physics.hist-ph physics.space-ph
Dim red aurora at low magnetic latitudes is a visual and recognized
manifestation of geomagnetic storms. The great low-latitude auroral displays
seen throughout East Asia on 16-18 September 1770 are considered to manifest
one of the greatest storms. Recently found 111 historical documents in East
Asia attest that these low-latitude auroral displays were succeeding for almost
9 nights during 10-19 September 1770 in the lowest magnetic latitude areas (<
30{\deg}). This suggests that the duration of the great magnetic storm is much
longer than usual. Sunspot drawings from 1770 reveals the fact that sunspots
area was twice as large as those observed in another great storm of 1859, which
substantiates this unusual storm activities in 1770. These spots likely ejected
several huge, sequential magnetic structures in short duration into
interplanetary space, resulting in spectacular world-wide aurorae in
mid-September 1770. These findings provide new insights about the history,
duration, and effects of extreme magnetic storms that may be valuable for those
who need to mitigate against extreme events.
| arxiv topic:astro-ph.SR physics.hist-ph physics.space-ph |
arxiv_dataset-90781711.0079 | Grove arctic curves from periodic cluster modular transformations
math.PR math.CO
Groves are spanning forests of a finite region of the triangular lattice that
are in bijection with Laurent monomials that arise in solutions of the cube
recurrence. We introduce a large class of probability measures on groves for
which we can compute exact generating functions for edge probabilities. Using
the machinery of asymptotics of multivariate generating functions, this lets us
explicitly compute arctic curves, generalizing the arctic circle theorem of
Petersen and Speyer. Our class of probability measures is sufficiently general
that the limit shapes exhibit all solid and gaseous phases expected from the
classification of EGMs in the resistor network model.
| arxiv topic:math.PR math.CO |
arxiv_dataset-90791711.0089 | Multivariate stochastic integrals with respect to independently
scattered random measures on {\delta}-rings
math.PR
In this paper we construct general vector-valued infinite-divisible
independently scattered random measures with values in $\mathbb{R}^m$ and their
corresponding stochastic integrals. Moreover, given such a random measure, the
class of all integrable matrix-valued deterministic functions is characterized
in terms of certain characteristics of the random measure. In addition a
general construction principle is presented.
| arxiv topic:math.PR |
arxiv_dataset-90801711.0099 | Cogenesis of LIGO Primordial Black Holes and Dark Matter
astro-ph.CO hep-ph
In this letter, we propose a novel scenario which simultaneously explains
$\mathcal{O}(10)M_\odot$ primordial black holes (PBHs) and dark matter in the
minimally supersymmetric standard model. Gravitational waves (GWs) events
detected by LIGO-Virgo collaboration suggest an existence of black holes as
heavy as $\sim 30M_\odot$. In our scenario, as seeds of the PBHs, we make use
of the baryon number perturbations which are induced by the special type of
Affleck-Dine mechanism. Furthermore, the scenario does not suffer from the
stringent constraints from CMB $\mu$-distortion due to the Silk damping and
pulsar timing. We find the scenario can explain not only the current GWs events
consistently, but also dark matter abundance by the non-topological solitons
formed after Affleck-Dine mechanism, called Q-balls.
| arxiv topic:astro-ph.CO hep-ph |
arxiv_dataset-90811711.0109 | Factorizations of almost simple groups with a factor having many
nonsolvable composition factors
math.GR
This paper classifies the factorizations of almost simple groups with a
factor having at least two nonsolvable composition factors. This together with
a previous classification result of the authors reduces the factorization
problem of almost simple groups to the case where both factors have a unique
nonsolvable composition factor.
| arxiv topic:math.GR |
arxiv_dataset-90821711.0119 | Bootstrap technique to study correlation between neutron skin thickness
and the slope of symmetry energy in atomic nuclei
nucl-th
We present a new statistical tool based on random sampling to assess the
confidence interval of Pearson's and Spearman's correlation coefficients. These
estimators are then used to quantify the statistical correlations among the
neutron skin thickness of atomic nuclei and the slope of the symmetry energy in
the infinite nuclear medium.
| arxiv topic:nucl-th |
arxiv_dataset-90831711.0129 | Transport of internetwork magnetic flux elements in the solar
photosphere
astro-ph.SR
The motions of small-scale magnetic flux elements in the solar photosphere
can provide some measure of the Lagrangian properties of the convective flow.
Measurements of these motions have been critical in estimating the turbulent
diffusion coefficient in flux-transport dynamo models and in determining the
Alfven wave excitation spectrum for coronal heating models. We examine the
motions of internetwork flux elements in a 24 hour long Hinode/NFI magnetogram
sequence with 90 second cadence, and study both the scaling of their mean
squared displacement and the shape of their displacement probability
distribution as a function of time. We find that the mean squared displacement
scales super-diffusively with a slope of about 1.48. Super-diffusive scaling
has been observed in other studies for temporal increments as small as 5
seconds, increments over which ballistic scaling would be expected. Using
high-cadence MURaM simulations, we show that the observed super-diffusive
scaling at short temporal increments is a consequence of random changes in the
barycenter positions due to flux evolution. We also find that for long temporal
increments, beyond granular lifetimes, the observed displacement distribution
deviates from that expected for a diffusive process, evolving from Rayleigh to
Gaussian. This change in the distribution can be modeled analytically by
accounting for supergranular advection along with motions due to granulation.
These results complicate the interpretation of magnetic element motions as
strictly advective or diffusive on short and long timescales and suggest that
measurements of magnetic element motions must be used with caution in turbulent
diffusion or wave excitation models. We propose that passive trace motions in
measured photospheric flows may yield more robust transport statistics.
| arxiv topic:astro-ph.SR |
arxiv_dataset-90841711.0139 | The density of rational points near hypersurfaces
math.NT math.CA
We establish a sharp asymptotic formula for the number of rational points up
to a given height and within a given distance from a hypersurface. Our main
innovation is a bootstrap method that relies on the synthesis of Poisson
summation, projective duality and the method of stationary phase. This has
surprising applications to counting rational points lying on the manifold;
indeed, we are able to prove an analogue of Serre's Dimension Growth Conjecture
(originally stated for projective varieties) in this general setup. As another
consequence of our main counting result, we obtain an optimal Jarn\'{i}k type
theorem for simultaneous approximation on hypersurfaces.
| arxiv topic:math.NT math.CA |
arxiv_dataset-90851711.0149 | Analyzing Material Recognition Performance of Thermal Tactile Sensing
using a Large Materials Database and a Real Robot
cs.RO
In this paper we focus on analyzing the thermal modality of tactile sensing
for material recognition using a large materials database. Many factors affect
thermal recognition performance, including sensor noise, the initial
temperatures of the sensor and the object, the thermal effusivities of the
materials, and the duration of contact. To analyze the influence of these
factors on thermal recognition, we used a semi-infinite solid based thermal
model to simulate heat-transfer data from all the materials in the CES Edupack
Level-1 database. We used support-vector machines (SVMs) to predict F1 scores
for binary material recognition for 2346 material pairs. We also collected data
using a real robot equipped with a thermal sensor and analyzed its material
recognition performance on 66 real-world material pairs. Additionally, we
analyzed the performance when the models were trained on the simulated data and
tested on the real-robot data. Our models predicted the material recognition
performance with a 0.980 F1 score for the simulated data, a 0.994 F1 score for
real-world data with constant initial sensor temperatures, a 0.966 F1 score for
real-world data with varied initial sensor temperatures, and a 0.815 F1 score
for sim-to-real transfer. Finally, we present some guidelines on sensor design
and parameter choice for thermal recognition based on the insights gained from
these results that would hopefully enable robotics researchers to use this
less-explored tactile sensing modality more effectively during physical
human-robot and robot-object interactions. We release our simulated and
real-robot datasets for further use by the robotics community.
| arxiv topic:cs.RO |
arxiv_dataset-90861711.0159 | Asymptotics of Polynomials Orthogonal with respect to a Logarithmic
Weight
math.CA math.CV
In this paper we compute the asymptotic behavior of the recurrence
coefficients for polynomials orthogonal with respect to a logarithmic weight
$w(x){\rm d}x = \log \frac{2k}{1-x}{\rm d}x$ on $(-1,1)$, $k > 1$, and verify a
conjecture of A. Magnus for these coefficients. We use
Riemann-Hilbert/steepest-descent methods, but not in the standard way as there
is no known parametrix for the Riemann-Hilbert problem in a neighborhood of the
logarithmic singularity at $x=1$.
| arxiv topic:math.CA math.CV |
arxiv_dataset-90871711.0169 | Search for light tetraquark states in $\Upsilon(1S)$ and $\Upsilon(2S)$
decays
hep-ex hep-ph
We search for the $J^{PC}=0^{--}$ and $1^{+-}$ light tetraquark states with
masses up to 2.46~GeV/$c^2$ in $\Upsilon(1S)$ and $\Upsilon(2S)$ decays with
data samples of $(102\pm 2)$ million and $(158\pm 4)$ million events,
respectively, collected with the Belle detector. No significant signals are
observed in any of the studied production modes, and 90\% credibility level
(C.L.) upper limits on their branching fractions in $\Upsilon(1S)$ and
$\Upsilon(2S)$ decays are obtained. The inclusive branching fractions of the
$\Upsilon(1S)$ and $\Upsilon(2S)$ decays into final states with $f_1(1285)$ are
measured to be ${\cal B}(\Upsilon(1S)\to f_1(1285)+anything)=(46\pm28({\rm
stat.})\pm13({\rm syst.}))\times 10^{-4}$ and ${\cal B}(\Upsilon(2S)\to
f_1(1285)+anything)=(22\pm15({\rm stat.})\pm6.3({\rm syst.}))\times 10^{-4}$.
The measured $\chi_{b2} \to J/\psi + anything$ branching fraction is measured
to be $(1.50\pm0.34({\rm stat.})\pm0.22({\rm syst.}))\times 10^{-3}$, and 90\%
C.L. upper limits for the $\chi_{b0,b1} \to J/\psi + anything$ branching
fractions are found to be $2.3\times 10^{-3}$ and $1.1\times 10^{-3}$,
respectively. For ${\cal B}(\chi_{b1} \to \omega + anything)$, the branching
fraction is measured to be $(4.9\pm1.3({\rm stat.})\pm0.6({\rm syst.}))\times
10^{-2}$. %($<3.68\times 10^{-2}$ at 90\% C.L.). All results reported here are
the first measurements for these modes.
| arxiv topic:hep-ex hep-ph |
arxiv_dataset-90881711.0179 | Simultaneous Block-Sparse Signal Recovery Using Pattern-Coupled Sparse
Bayesian Learning
cs.LG cs.IT eess.SP math.IT stat.ML
In this paper, we consider the block-sparse signals recovery problem in the
context of multiple measurement vectors (MMV) with common row sparsity
patterns. We develop a new method for recovery of common row sparsity MMV
signals, where a pattern-coupled hierarchical Gaussian prior model is
introduced to characterize both the block-sparsity of the coefficients and the
statistical dependency between neighboring coefficients of the common row
sparsity MMV signals. Unlike many other methods, the proposed method is able to
automatically capture the block sparse structure of the unknown signal. Our
method is developed using an expectation-maximization (EM) framework.
Simulation results show that our proposed method offers competitive performance
in recovering block-sparse common row sparsity pattern MMV signals.
| arxiv topic:cs.LG cs.IT eess.SP math.IT stat.ML |
arxiv_dataset-90891711.0189 | Intrinsic bounds of a two-qudit random evolution
quant-ph
We investigate entangled qudits evolving under random, local $SU(d)$
operations and demonstrate that this evolution is constrained by intrinsic
bounds, showing robust features of two-qudit entangled states that can be
useful for fault tolerant implementations of phase gates. Our analytical
results are supported by numerical simulations and confirmed by experiments on
liquid-state nuclear magnetic resonance qubits.
| arxiv topic:quant-ph |
arxiv_dataset-90901711.0199 | Cluster-based Generalized Multiscale Finite Element Method for elliptic
PDEs with random coefficients
math.NA
We propose a generalized multiscale finite element method (GMsFEM) based on
clustering algorithm to study the elliptic PDEs with random coefficients in the
multi-query setting. Our method consists of offline and online stages. In the
offline stage, we construct a small number of reduced basis functions within
each coarse grid block, which can then be used to approximate the multiscale
finite element basis functions. In addition, we coarsen the corresponding
random space through a clustering algorithm. In the online stage, we can obtain
the multiscale finite element basis very efficiently on a coarse grid by using
the pre-computed multiscale basis. The new GMsFEM can be applied to multiscale
SPDE starting with a relatively coarse grid, without requiring the coarsest
grid to resolve the smallest-scale of the solution. The new method offers
considerable savings in solving multiscale SPDEs. Numerical results are
presented to demonstrate the accuracy and efficiency of the proposed method for
several multiscale stochastic problems without scale separation.
| arxiv topic:math.NA |
arxiv_dataset-90911711.0209 | Very low-luminosity galaxies in the early universe have observed sizes
similar to single star cluster complexes
astro-ph.GA
We compare the sizes and luminosities of 307 faint z=6-8 sources revealed by
the Hubble Frontier Fields (HFF) program with sources in the nearby universe.
Making use of the latest lensing models and data from the first four HFF
clusters with an extensive suite of public lens models, we measure both the
sizes and luminosities for 153 z~6, 101 z~7, and 53 z~8 galaxies. The sizes
range over more than a decade from ~500 to <50 pc. Extremely small sizes are
inferred for many of our lowest luminosity sources, reaching individual sizes
as small as 10-30 pc (the smallest is 11(-6)(+28) pc). The uncertainty in these
measures ranges from 80 pc for the largest sources to typically about 20 pc for
the smallest. Such sizes are smaller than extrapolations of the size-luminosity
relation, and expectations for the completeness of our faint samples,
suggesting a likely break in the size-luminosity relation at ~-17 mag with size
proportional to L**(0.50(-0.11)(+0.10)). The sizes and luminosities of the
lowest-luminosity sources are similar to those of single star cluster complexes
like 30 Doradus in the lower-redshift universe and -- in a few cases -- super
star clusters. Remarkably, our identification of these compact, faint
star-forming sources in the z~6-8 universe also allow us to set upper limits on
the proto-globular cluster LF at z~6. Comparisons with recent models allow us
to rule out (with some caveats) some scenarios for proto-globular cluster
formation and set useful upper limits on other less extreme ones. Our results
suggest we may be very close to discovering a bona-fide population of forming
globular clusters at high redshift.
| arxiv topic:astro-ph.GA |
arxiv_dataset-90921711.0219 | Anomalous effects of dense matter under rotation
hep-ph cond-mat.mes-hall hep-th nucl-th
We study the anomaly induced effects of dense baryonic matter under rotation.
We derive the anomalous terms that account for the chiral vortical effect in
the low-energy effective theory for light Nambu-Goldstone modes. The anomalous
terms lead to new physical consequences, such as the anomalous Hall energy
current and spontaneous generation of angular momentum in a magnetic field (or
spontaneous magnetization by rotation). In particular, we show that, due to the
presence of such anomalous terms, the ground state of the quantum
chromodynamics (QCD) under sufficiently fast rotation becomes the "chiral
soliton lattice" of neutral pions that has lower energy than the QCD vacuum and
nuclear matter. We briefly discuss the possible realization of the chiral
soliton lattice induced by a fast rotation in noncentral heavy ion collisions.
| arxiv topic:hep-ph cond-mat.mes-hall hep-th nucl-th |
arxiv_dataset-90931711.0229 | Intelligent Collision Management in Dynamic Environments for
Human-Centered Robots
cs.RO
In this context, a major focus of this thesis is on unintentional collisions,
where a straight goal is to eliminate injury from users and passerby's via
realtime sensing and control systems. A less obvious focus is to combine
collision response with tools from motion planning in order to produce
intelligent safety behaviors that ensure the safety of multiple people or
objects. Yet, an even more challenging problem is to anticipate future
collisions between objects external to the robot and have the robot intervene
to prevent imminent accidents. In this dissertation, we study all of these
sophisticated flavors of collision reaction and intervention. We investigate
in-depth multiple key and interesting topics related to collisions and safety
of mobile robots and robotic manipulators operating in human environments.
Overall we deeply investigate collisions from many perspectives and develop
techniques that borrow and contribute to the areas of mechatronic design,
sensor processing, feedback controls, motion planning, and probabilistic
reasoning methods. The result of this study is a set of key experiments and
guidelines to deal with collisions in mobile robots and robotic manipulators.
This study aims at influencing future studies on field operations of robots and
accelerate the employment of advanced robots in our daily environments without
compromising our safety.
| arxiv topic:cs.RO |
arxiv_dataset-90941711.0239 | Negative magnetic eddy diffusivity due to oscillogenic $\alpha$-effect
physics.flu-dyn astro-ph.SR math.AP nlin.CD
We study large-scale kinematic dynamo action of steady mirror-antisymmetric
flows of incompressible fluid, that involve small spatial scales only, by
asymptotic methods of the multiscale stability theory. It turns out that, due
to the magnetic $\alpha$-effect in such flows, the large-scale mean field
experiences harmonic oscillations in time on the scale O($\varepsilon t$)
without growth or decay. Here $\varepsilon$ is the spatial scale ratio and $t$
is the fast time of the order of the flow turnover time. The interaction of the
accompanying fluctuating magnetic field with the flow gives rise to an
anisotropic magnetic eddy diffusivity, whose dependence on the direction of the
large-scale wave vector generically exhibits a singular behaviour, and thus to
negative eddy diffusivity for whichever molecular magnetic diffusivity.
Consequently, such flows always act as kinematic dynamos on the time scale
O($\varepsilon^2t$); for the directions at which eddy diffusivity is infinite,
the large-scale mean-field growth rate is finite on the scale
O($\varepsilon^{3/2}t$). We investigate numerically this dynamo mechanism for
two sample flows.
| arxiv topic:physics.flu-dyn astro-ph.SR math.AP nlin.CD |
arxiv_dataset-90951711.0249 | On the T-dual renormalisation of entanglement entropy
hep-th
Imposing T-duality in the renormalisation process of entanglement entropy
leads to new relations between entanglement entropy counter-terms. T-duality is
made explicit by means of the generalised metric of double field theory in the
context of bulk-boundary duality. Double field theory in the bulk naturally
provides the new relations between higher order quantum corrections to
entanglement entropy as well as a systematic approach to understanding
entanglement entropy renormalisation counter-terms. An analogue for
Slavnov-Taylor identities for T-dual counter-terms of entanglement entropy is
envisaged.
| arxiv topic:hep-th |
arxiv_dataset-90961711.0259 | Non-uniqueness and mean-field criticality for percolation on
nonunimodular transitive graphs
math.PR math-ph math.MP
We study Bernoulli bond percolation on nonunimodular quasi-transitive graphs,
and more generally graphs whose automorphism group has a nonunimodular
quasi-transitive subgroup. We prove that percolation on any such graph has a
non-empty phase in which there are infinite light clusters, which implies the
existence of a non-empty phase in which there are infinitely many infinite
clusters. That is, we show that $p_c<p_h \leq p_u$ for any such graph. This
answers a question of Haggstrom, Peres, and Schonmann (1999), and verifies the
nonunimodular case of a well-known conjecture of Benjamini and Schramm (1996).
We also prove that the triangle condition holds at criticality on any such
graph, which implies that various critical exponents exist and take their
mean-field values.
All our results apply, for example, to the product $T_k\times \mathbb{Z}^d$
of a $k$-regular tree with $\mathbb{Z}^d$ for $k\geq 3$ and $d \geq 1$, for
which these results were previously known only for large $k$. Furthermore, our
methods also enable us to establish the basic topological features of the phase
diagram for anisotropic percolation on such products, in which tree edges and
$\mathbb{Z}^d$ edges are given different retention probabilities. These
features had only previously been established for $d=1$, $k$ large.
| arxiv topic:math.PR math-ph math.MP |
arxiv_dataset-90971711.0269 | Holography Beyond AdS
hep-th
We continue our study of string theory in a background that interpolates
between $AdS_3$ in the infrared and a linear dilaton spacetime $R^{1,1}\times
R_\phi$ in the UV. This background corresponds via holography to a $CFT_2$
deformed by a certain irrelevant operator of dimension $(2,2)$. We show that
for two point functions of local operators in the infrared CFT, conformal
perturbation theory in this irrelevant operator has a finite radius of
convergence in momentum space, and one can use it to flow up the
renormalization group. The spectral density develops an imaginary part above a
certain critical value of the spectral parameter; this appears to be related to
the non-locality of the theory. In position space, conformal perturbation
theory has a vanishing radius of convergence; the leading non-perturbative
effect is an imaginary part of the two point function.
| arxiv topic:hep-th |
arxiv_dataset-90981711.0279 | On diagrams of simplified trisections and mapping class groups
math.GT
A simplified trisection is a trisection map on a 4-manifold such that, in its
critical value set, there is no double point and cusps only appear in triples
on innermost fold circles. We give a necessary and sufficient condition for a
3-tuple of systems of simple closed curves in a surface to be a diagram of a
simplified trisection in terms of mapping class groups. As an application of
this criterion, we show that trisections of spun 4-manifolds due to Meier are
diffeomorphic (as trisections) to simplified ones. Baykur and Saeki recently
gave an algorithmic construction of a simplified trisection from a directed
broken Lefschetz fibration. We also give an algorithm to obtain a diagram of a
simplified trisection derived from their construction.
| arxiv topic:math.GT |
arxiv_dataset-90991711.0289 | FliPer: Checking the reliability of global seismic parameters from
automatic pipelines
astro-ph.SR
Our understanding of stars through asteroseismic data analysis is limited by
our ability to take advantage of the huge amount of observed stars provided by
space missions such as CoRoT, Kepler, K2, and soon TESS and PLATO. Global
seismic pipelines provide global stellar parameters such as mass and radius
using the mean seismic parameters, as well as the effective temperature. These
pipelines are commonly used automatically on thousands of stars observed by K2
for 3 months (and soon TESS for at least around 1 month). However, pipelines
are not immune from misidentifying noise peaks and stellar oscillations.
Therefore, new validation techniques are required to assess the quality of
these results. We present a new metric called FliPer (Flicker in Power), which
takes into account the average variability at all measured time scales. The
proper calibration of FliPer enables us to obtain good estimations of global
stellar parameters such as surface gravity that are robust against the
influence of noise peaks and hence are an excellent way to find faults in
asteroseismic pipelines.
| arxiv topic:astro-ph.SR |
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