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arxiv_dataset-78001610.04653 | Thermal Properties and an Improved Shape Model for Near-Earth Asteroid
(162421) 2000 ET70
astro-ph.EP
We present thermal properties and an improved shape model for potentially
hazardous asteroid (162421) 2000 ET70. In addition to the radar data from 2000
ET70's apparition in 2012, our model incorporates optical lightcurves and
infrared spectra that were not included in the analysis of Naidu et al. (2013,
Icarus 226, 323-335). We confirm the general "clenched fist" appearance of the
Naidu et al. model, but compared to their model, our best-fit model is about
10% longer along its long principal axis, nearly identical along the
intermediate axis, and about 25% shorter along the short axis. We find the
asteroid's dimensions to be 2.9 km $\times$ 2.2 km $\times$ 1.5 km (with
relative uncertainties of about 10%, 15%, and 25%, respectively). With the
available data, 2000 ET70's period and pole position are degenerate with each
other. The radar and lightcurve data together constrain the pole direction to
fall along an arc that is about twenty-three degrees long and eight degrees
wide. Infrared spectra from the NASA InfraRed Telescope Facility (IRTF) provide
an additional constraint on the pole. Thermophysical modeling, using our
SHERMAN software, shows that only a subset of the pole directions, about twelve
degrees of that arc, are compatible with the infrared data. Using all of the
available data, we find that 2000 ET70 has a sidereal rotation period of 8.944
hours ($\pm$ 0.009 h) and a north pole direction of ecliptic coordinates
$(52^{\circ}, -60^{\circ}) \pm 6^{\circ}$. The infrared data, acquired over
several dates, require that the thermal properties (albedo, thermal inertia,
surface roughness) must change across the asteroid's surface. By incorporating
the detailed shape model and spin state into our thermal modeling, the multiple
ground-based observations at different viewing geometries have allowed us to
constrain the levels of the variations in the surface properties.
| arxiv topic:astro-ph.EP |
arxiv_dataset-78011610.04753 | Black hole feeding and feedback: the physics inside the "subgrid"
astro-ph.GA astro-ph.CO
Black holes (BHs) are believed to be a key ingredient of galaxy formation.
However, the galaxy-BH interplay is challenging to study due to the large
dynamical range and complex physics involved. As a consequence, hydrodynamical
cosmological simulations normally adopt sub-grid models to track the unresolved
physical processes, in particular BH accretion; usually the spatial scale where
the BH dominates the hydrodynamical processes (the Bondi radius) is unresolved,
and an approximate Bondi-Hoyle accretion rate is used to estimate the growth of
the BH. By comparing hydrodynamical simulations at different resolutions (300,
30, 3 pc) using a Bondi-Hoyle approximation to sub-parsec runs with
non-parameterized accretion, our aim is to probe how well an approximated Bondi
accretion is able to capture the BH accretion physics and the subsequent
feedback on the galaxy. We analyse an isolated galaxy simulation that includes
cooling, star formation, Type Ia and Type II supernovae, BH accretion and AGN
feedback (radiation pressure, Compton heating/cooling) where mass, momentum,
and energy are deposited in the interstellar medium through conical winds. We
find that on average the approximated Bondi formalism can lead to both over-
and under-estimations of the BH growth, depending on resolution and on how the
variables entering into the Bondi-Hoyle formalism are calculated.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-78021610.04853 | Dynamical analysis of NGC 110: cluster of fainter stars or data
fluctuation?
astro-ph.SR astro-ph.GA
The stellar enhancement of the cluster NGC 110 is investigated in various
optical and infrared (IR) bands. The radial density profile of the IR region
does not show a stellar enhancement in the central region of the cluster. This
stellar deficiency may be occurring by undetected fainter stars due to the
contamination effect of massive stars. Since, our analysis is not indicating
the stellar enhancement below 16.5 mag of I band, therefore the cluster is
assumed to be a group of fainter stars. The proposed magnitude scatter factor
would be an excellent tool to understand the characteristic of
colour-scattering of stars. The most probable members do not coincide with the
model isochronic fitting in the optical bands due to poor data quality of P P
MXL catalogue. The different values of the mean proper motions are found for
the fainter stars of the cluster and field regions, whereas similar values are
obtained for radial zones of the cluster. The symmetrical distribution of
fainter stars of the core are found around the best solution of isochrone. The
mass function and mass segregation studies are not possible due to higher
uncertainty of the photometric data. The number of the massive stars of the
cluster region is low in comparison with the field region due to completed
evolution life of the massive stars.
| arxiv topic:astro-ph.SR astro-ph.GA |
arxiv_dataset-78031610.04953 | Magnetic Chirality Induced from Ruderman-Kittel-Kasuya-Yosida
Interaction at an Interface of a Ferromagnet/Heavy Metal Heterostructure
cond-mat.mtrl-sci cond-mat.str-el
We study a microscopic derivation and the properties of the
Dzyaloshinskii-Moriya interaction (DMI) between local magnetic moments in
ferromagnet/heavy metal heterostructures. First, we derive DMI by
Ruderman-Kittel-Kasuya-Yosida interaction through electrons in a heavy metal
with Rashba spin orbit interaction (SOI). Next, we study the dependences of the
DMI on the Rashba SOI, lattice constant, and chemical potential. We find that
the DMI amplitude increases linearly when the Rashba SOI is small, has a
maximum when the Rashba SOI is comparable to the hopping integral, and
decreases when the Rashba SOI is large. The sign of the DMI not only changes
depending on the sign of the Rashba SOI but also the lattice constants and the
chemical potential of the heavy metal. The implications of the obtained results
for experiments are discussed.
| arxiv topic:cond-mat.mtrl-sci cond-mat.str-el |
arxiv_dataset-78041610.05053 | Pach's selection theorem does not admit a topological extension
math.CO
Let $U_1,\dots, U_{d+1}$ be $n$-element sets in $R^d$ and let $\langle
u_1,\ldots,u_{d+1}\rangle$ denote the convex hull of points $u_i$ in $U_i$ (for
all $i$) which is a (possibly degenerate) simplex. Pach's selection theorem
says that there are sets $Z_1 \subset U_1,\dots, Z_{d+1} \subset U_{d+1}$ and a
point $u$ in $R^d$ such that each $|Z_i| > c_1(d)n$ and $u$ belongs to $\langle
z_1,...,z_{d+1} \rangle$ for every choice of $z_1$ in $Z_1,\dots,z_{d+1}$ in
$Z_{d+1}$. Here we show that this theorem does not admit a topological
extension with linear size sets $Z_i$. However, there is a topological
extension where each $|Z_i|$ is of order $(\log n)^(1/d)$.
| arxiv topic:math.CO |
arxiv_dataset-78051610.05153 | Coherent Atom-Phonon Interaction through Mode Field Coupling in Hybrid
Optomechanical Systems
quant-ph physics.optics
We propose a novel type of optomechanical coupling which enables a tripartite
interaction between a quantum emitter, an optical mode and a macroscopic
mechanical oscillator. The interaction uses a mechanism we term mode field
coupling: mechanical displacement modifies the spatial distribution of the
optical mode field, which in turn modulates the atom-photon coupling rate. In
properly designed multimode optomechanical systems, we can achieve situations
in which mode field coupling is the only possible interaction pathway for the
system. This enables, for example, swapping of a single excitation between
emitter and phonon, creation of nonclassical states of motion and mechanical
ground-state cooling in the bad-cavity regime. Importantly, the emitter-phonon
coupling rate can be enhanced through an optical drive field, allowing active
control of strong atom-phonon coupling for realistic experimental parameters.
| arxiv topic:quant-ph physics.optics |
arxiv_dataset-78061610.05253 | Recent Experiments At Ndcx-II: Irradiation Of Materials Using Short,
Intense Ion Beams
physics.acc-ph
We present an overview of the performance of the Neutralized Drift
Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and summarize
recent studies of material properties created with nanosecond and
millimeter-scale ion beam pulses. The scientific topics being explored include
the dynamics of ion induced damage in materials, materials synthesis far from
equilibrium, warm dense matter and intense beam-plasma physics. We summarize
the improved accelerator performance, diagnostics and results of beam-induced
irradiation of thin samples of, e.g., tin and silicon. Bunches with over
3x10^10 ions, 1- mm radius, and 2-30 ns FWHM duration have been created. To
achieve these short pulse durations and mm-scale focal spot radii, the 1.2 MeV
He+ ion beam is neutralized in a drift compression section which removes the
space charge defocusing effect during final compression and focusing.
Quantitative comparison of detailed particle-in-cell simulations with the
experiment play an important role in optimizing accelerator performance; these
keep pace with the accelerator repetition rate of ~1/minute.
| arxiv topic:physics.acc-ph |
arxiv_dataset-78071610.05353 | Classification of Homogeneous Fourier Matrices
math.RA
Modular data are commonly studied in mathematics and physics. A modular datum
defines a finite-dimensional representation of the modular group
$SL_2(\mathbb{Z})$. In this paper, we show that there is a one-to-one
correspondence between Fourier matrices associated to modular data and
self-dual $C$-algebras that satisfy a certain condition. Also, we prove that a
homogenous $C$-algebra arising from a Fourier matrix has all the degrees equal
to $1$.
| arxiv topic:math.RA |
arxiv_dataset-78081610.05453 | Iterated convolutions and endless Riemann surfaces
math.DS
We discuss a version of \'Ecalle's definition of resurgence, based on the
notion of endless continuability in the Borel plane. We relate this with the
notion of \Omega-continuability, where \Omega\ is a discrete filtered set, and
show how to construct a universal Riemann surface X_\Omega\ whose holomorphic
functions are in one-to-one correspondence with \Omega-continuable functions.
We then discuss the \Omega-continuability of convolution products and give
estimates for iterated convolutions of the form \hat\phi_1*\cdots *\hat\phi_n.
This allows us to handle nonlinear operations with resurgent series, e.g.
substitution into a convergent power series.
| arxiv topic:math.DS |
arxiv_dataset-78091610.05553 | Criteria of convergence of a non ordinary random continued fractions on
a symmetric cone
math.PR
In this paper, we use a notion of ratio based on a division algorithm, to
extend to a symmetric cone the definition of a continued fraction in its more
general form. We then give a criteria of convergence of a non ordinary random
continued fraction that has arisen in the study of some probability
distributions related to the beta distribution on the cone of positive definite
symmetric matrices or on any symmetric cone.
| arxiv topic:math.PR |
arxiv_dataset-78101610.05653 | Acoustic Reflector Localization: Novel Image Source Reversion and Direct
Localization Methods
cs.SD
Acoustic reflector localization is an important issue in audio signal
processing, with direct applications in spatial audio, scene reconstruction,
and source separation. Several methods have recently been proposed to estimate
the 3D positions of acoustic reflectors given room impulse responses (RIRs). In
this article, we categorize these methods as "image-source reversion", which
localizes the image source before finding the reflector position, and "direct
localization", which localizes the reflector without intermediate steps. We
present five new contributions. First, an onset detector, called the clustered
dynamic programming projected phase-slope algorithm, is proposed to
automatically extract the time of arrival for early reflections within the RIRs
of a compact microphone array. Second, we propose an image-source reversion
method that uses the RIRs from a single loudspeaker. It is constructed by
combining an image source locator (the image source direction and range (ISDAR)
algorithm), and a reflector locator (using the loudspeaker-image bisection
(LIB) algorithm). Third, two variants of it, exploiting multiple loudspeakers,
are proposed. Fourth, we present a direct localization method, the ellipsoid
tangent sample consensus (ETSAC), exploiting ellipsoid properties to localize
the reflector. Finally, systematic experiments on simulated and measured RIRs
are presented, comparing the proposed methods with the state-of-the-art. ETSAC
generates errors lower than the alternative methods compared through our
datasets. Nevertheless, the ISDAR-LIB combination performs well and has a run
time 200 times faster than ETSAC.
| arxiv topic:cs.SD |
arxiv_dataset-78111610.05753 | Enthalpy, Geometric Volume and Logarithmic correction to Entropy for
Van-der-Waals Black Hole
gr-qc hep-th
If the negative cosmological constant is treated as a dynamical pressure and
if the volume be its thermodynamically conjugate variable then the
gravitational mass can be expressed as the total gravitational enthalpy rather
than the energy. Under these circumstances, a new phenomena emerges in the
context of extended phase space thermodynamics. We \emph{examine} here these
features for recently discovered Van-der-Waal (VDW) black hole (BH)
\cite{mann15} which is analogous to the VDW fluid. We show that the
thermodynamic volume is \emph{greater} than the naive geometric volume. We also
show that the \emph{Smarr-Gibbs-Duhem} relation is satisfied for this BH.
Furthermore, by computing the thermal specific heat we find the local
thermodynamic stability criterion for this BH. It has been observed that the BH
does \emph{not} possess any kind of second order phase transition. This is an
interesting feature of VDW BH by its own right. Moreover, we also derive
\emph{Cosmic-Censorship-Inequality} for this class of BH. In addition finally,
we compute the \emph{logarithmic correction} to the entropy of this BH due to
the quantum fluctuations around the thermal equilibrium.
| arxiv topic:gr-qc hep-th |
arxiv_dataset-78121610.05853 | A new identity of Dickson polynomials
math.NT math.AG
A new polynomial identity is found for Dickson polynomials in characteristic
2. The identity is used to prove that the two polynomials $x^{q+1}+x+1/a$ and
$C(x)+a$ have the same splitting field over $F$, where $F$ is a field of
characteristic 2, $a$ is a nonzero element of $F$, $q=2^n>2$, and $C(x) = x
(\sum_{i=0}^{n-1} x^{2^i-1})^{q+1}$ is a M\"uller--Cohen--Matthews polynomial
of degree $(q^2-q)/2$. In addition, a new proof is obtained for the known
result that $C(x)$ induces a permutation on $F_{2^m}$ if $2m$ and $n$ are
relatively prime.
| arxiv topic:math.NT math.AG |
arxiv_dataset-78131610.05953 | Toroidal figures of equilibrium from a 2nd-order accurate, accelerated
SCF-method with subgrid approach
astro-ph.GA
We compute the structure of a self-gravitating torus with polytropic
equation-of-state (EOS) rotating in an imposed centrifugal potential. The
Poisson-solver is based on isotropic multigrid with optimal covering factor
(fluid section-to-grid area ratio). We work at $2$nd-order in the grid
resolution for both finite difference and quadrature schemes. For soft EOS
(i.e. polytropic index $n \ge 1$), the underlying $2$nd-order is naturally
recovered for Boundary Values (BVs) and any other integrated quantity sensitive
to the mass density (mass, angular momentum, volume, Virial Parameter, etc.),
i.e. errors vary with the number $N$ of nodes per direction as $\sim 1/N^2$.
This is, however, not observed for purely geometrical quantities (surface area,
meridional section area, volume), unless a subgrid approach is considered (i.e.
boundary detection). Equilibrium sequences are also much better described,
especially close to critical rotation. Yet another technical effort is required
for hard EOS ($n < 1$), due to infinite mass density gradients at the fluid
surface. We fix the problem by using kernel splitting. Finally, we propose an
accelerated version of the SCF-algorithm based on a node-by-node
pre-conditionning of the mass density at each step. The computing time is
reduced by a factor $2$ typically, regardless of the polytropic index. There is
a priori no obstacle to applying these results and techniques to ellipsoidal
configurations and even to $3$D-configurations.
| arxiv topic:astro-ph.GA |
arxiv_dataset-78141610.06053 | Chinese Restaurant Process for cognate clustering: A threshold free
approach
cs.CL
In this paper, we introduce a threshold free approach, motivated from Chinese
Restaurant Process, for the purpose of cognate clustering. We show that our
approach yields similar results to a linguistically motivated cognate
clustering system known as LexStat. Our Chinese Restaurant Process system is
fast and does not require any threshold and can be applied to any language
family of the world.
| arxiv topic:cs.CL |
arxiv_dataset-78151610.06153 | Near Threshold Effects on Recombination and Vibrational Relaxation in
Efimov Systems
physics.atom-ph
We investigate the energy dependence of inelastic processes in systems which
possess Efimov states. We consider the three-body recombination rate $K_3$
where three free atoms interact to produce an atom--dimer pair, and the
relaxation rate $K_{\rm rel}$ where an atom quenches a weakly bound state of a
dimer near an Efimov resonance to more deeply bound levels. Using a model
capturing the key features of the Efimov problem, we identify new energy
regimes for $K_3$, namely the NTR (Near Threshold Resonance) regime behavior
$E^{-2}$ for negative scattering lengths and the NTS (Near Threshold
Suppression) regime behavior $E^2$ for positive scattering lengths. We also
confirm a previously found oscillatory behavior of $K_3$ at higher energy $E$.
Finally, we find that $K_{\rm rel}$ behaves as $E^{-1}$ in the NTR regime.
| arxiv topic:physics.atom-ph |
arxiv_dataset-78161610.06253 | First-principles analysis of electron transport in BaSnO$_3$
cond-mat.mtrl-sci
BaSnO$_3$ (BSO) is a promising transparent conducting oxide (TCO) with
reported room-temperature (RT) Hall mobility exceeding 320
cm$^{2}$V$^{-1}$s$^{-1}$. Among perovskite oxides, it has the highest RT
mobility, about 30 times higher than that of the prototypical SrTiO$_3$. Using
first-principles calculations based on hybrid density functional theory, we
elucidate the physical mechanisms that govern the mobility by studying the
details of LO-phonon and ionized impurity scattering. A careful numerical
analysis to obtain converged results within the relaxation-time approximation
of Boltzmann transport theory is presented. The ${\bf k}$ dependence of the
relaxation time is fully taken into account. We find that the high RT mobility
in BSO originates not only from a small effective mass, but also from a
significant reduction in the phonon scattering rate compared to other
perovskite oxides; the origins of this reduction are identified. Ionized
impurity scattering influences the total mobility even at RT for dopant
densities larger than $5\times10^{18}$ cm$^{-3}$, and becomes comparable to
LO-phonon scattering for $1\times10^{20}$ cm$^{-3}$ doping, reducing the drift
mobility from its intrinsic LO-phonon-limited value of $\sim$594
cm$^{2}$V$^{-1}$s$^{-1}$ to less than 310 cm$^{2}$V$^{-1}$s$^{-1}$. We suggest
pathways to avoid impurity scattering via modulation doping or polar
discontinuity doping. We also explicitly calculate the Hall factor and Hall
mobility, allowing a direct comparison to experimental reports for bulk and
thin films and providing insights into the nature of the dominant mechanisms
that limit mobility in state-of-the art samples.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-78171610.06353 | Grain-scale Modeling and Splash Parametrization for Aeolian Sand
Transport
cond-mat.soft
The collision of a spherical grain with a granular bed is commonly
parametrized by the splash function, which provides the velocity of the
rebounding grain and the velocity distribution and number of ejected grains.
Starting from elementary geometric considerations and physical principles, like
momentum conservation and energy dissipation in inelastic pair collisions, we
derive a rebound parametrization for the collision of a spherical grain with a
granular bed. Combined with a recently proposed energy-splitting model [Ho
${\it et\ al.}$, Phys. Rev. E 85, 052301 (2012)] that predicts how the impact
energy is distributed among the bed grains, this yields a coarse-grained but
complete characterization of the splash as a function of the impact velocity
and the impactor-bed grain-size ratio. The predicted mean values of the rebound
angle, total and vertical restitution, ejection speed, and number of ejected
grains are in excellent agreement with experimental literature data and with
our own discrete-element computer simulations. We extract a set of analytical
asymptotic relations for shallow impact geometries, which can readily be used
in coarse-grained analytical modeling or computer simulations of geophysical
particle-laden flows.
| arxiv topic:cond-mat.soft |
arxiv_dataset-78181610.06453 | Change-point Detection Methods for Body-Worn Video
cs.CV cs.LG stat.ML
Body-worn video (BWV) cameras are increasingly utilized by police departments
to provide a record of police-public interactions. However, large-scale BWV
deployment produces terabytes of data per week, necessitating the development
of effective computational methods to identify salient changes in video. In
work carried out at the 2016 RIPS program at IPAM, UCLA, we present a novel
two-stage framework for video change-point detection. First, we employ
state-of-the-art machine learning methods including convolutional neural
networks and support vector machines for scene classification. We then develop
and compare change-point detection algorithms utilizing mean squared-error
minimization, forecasting methods, hidden Markov models, and maximum likelihood
estimation to identify noteworthy changes. We test our framework on detection
of vehicle exits and entrances in a BWV data set provided by the Los Angeles
Police Department and achieve over 90% recall and nearly 70% precision --
demonstrating robustness to rapid scene changes, extreme luminance differences,
and frequent camera occlusions.
| arxiv topic:cs.CV cs.LG stat.ML |
arxiv_dataset-78191610.06553 | A note on the Schur-finiteness of linear sections
math.AG math.AT math.KT math.RT
Making use of the recent theory of noncommutative motives, we prove that
Schur-finiteness in the setting of Voevodsky's mixed motives is invariant under
homological projective duality. As an application, we show that the mixed
motives of smooth linear sections of certain (Lagrangian) Grassmannians, spinor
varieties, and determinantal varieties, are Schur-finite. Finally, we upgrade
our applications from Schur-finiteness to Kimura-finiteness.
| arxiv topic:math.AG math.AT math.KT math.RT |
arxiv_dataset-78201610.06653 | Achiral symmetry breaking and positive Gaussian modulus lead to
scalloped colloidal membranes
cond-mat.soft
In the presence of a non-adsorbing polymer, monodisperse rod-like particles
assemble into colloidal membranes, which are one rod-length thick liquid-like
monolayers of aligned rods. Unlike 3D edgeless bilayer vesicles, colloidal
monolayer membranes form open structures with an exposed edge, thus presenting
an opportunity to study physics of thin elastic sheets. Membranes assembled
from single-component chiral rods form flat disks with uniform edge twist. In
comparison, membranes comprised of mixture of rods with opposite chiralities
can have the edge twist of either handedness. In this limit disk-shaped
membranes become unstable, instead forming structures with scalloped edges,
where two adjacent lobes with opposite handedness are separated by a
cusp-shaped point defect. Such membranes adopt a 3D configuration, with cusp
defects alternatively located above and below the membrane plane. In the
achiral regime the cusp defects have repulsive interactions, but away from this
limit we measure effective long-ranged attractive binding. A phenomenological
model shows that the increase in the edge energy of scalloped membranes is
compensated by concomitant decrease in the deformation energy due to Gaussian
curvature associated with scalloped edges, demonstrating that colloidal
membranes have positive Gaussian modulus. A simple excluded volume argument
predicts the sign and magnitude of the Gaussian curvature modulus that is in
agreement with experimental measurements. Our results provide insight into how
the interplay between membrane elasticity, geometrical frustration and achiral
symmetry breaking can be used to fold colloidal membranes into 3D shapes.
| arxiv topic:cond-mat.soft |
arxiv_dataset-78211610.06753 | Getting Stuck: Using Monosignatures to Test Highly Ionizing Particles
hep-ph hep-ex
In this paper we argue that monojet and monophoton searches can be a
sensitive test of very highly ionizing particles such as particles with charges
$\gtrsim 150e$ and more generally particles that do not reach the outer parts
of the detector. 8 TeV monojet data from the CMS experiment excludes such
objects with masses in the range $\lesssim 650~{\text{GeV}}$ and charges
$\gtrsim 100e$. This nicely complements searches for highly ionizing objects at
ALICE, ATLAS, CMS and LHCb. Expected improvements in these channels will extend
the sensitivity range to $m\lesssim 750~{\text{GeV}}$. This search strategy can
directly be generalized to other particles that strongly interact with the
detector material, such as e.g. magnetic monopoles.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-78221610.06853 | Spark Level Sparsity and the $\ell_1$ Tail Minimization
cs.IT math.FA math.IT
Solving compressed sensing problems relies on the properties of sparse
signals. It is commonly assumed that the sparsity s needs to be less than one
half of the spark of the sensing matrix A, and then the unique sparsest
solution exists, and recoverable by $\ell_1$-minimization or related
procedures. We discover, however, a measure theoretical uniqueness exists for
nearly spark-level sparsity from compressed measurements Ax = b. Specifically,
suppose A is of full spark with m rows, and suppose $\frac{m}{2}$ < s < m. Then
the solution to Ax = b is unique for x with $\|x\|_0 \leq s$ up to a set of
measure 0 in every s-sparse plane. This phenomenon is observed and confirmed by
an $\ell_1$-tail minimization procedure, which recovers sparse signals uniquely
with s > $\frac{m}{2}$ in thousands and thousands of random tests. We further
show instead that the mere $\ell_1$-minimization would actually fail if s >
$\frac{m}{2}$ even from the same measure theoretical point of view.
| arxiv topic:cs.IT math.FA math.IT |
arxiv_dataset-78231610.06953 | Estimation and simulation of foraging trips in land-based marine
predators
q-bio.QM stat.AP
The behaviour of colony-based marine predators is the focus of much research
globally. Large telemetry and tracking data sets have been collected for this
group of animals, and are accompanied by many theoretical studies of optimal
foraging strategies. However, relatively few studies have detailed statistical
methods for inferring behaviours in central place foraging trips. In this paper
we describe an approach based on hidden Markov models, which splits foraging
trips into segments labelled as "outbound", "search", "forage", and "inbound".
By structuring the hidden Markov model transition matrix appropriately, the
model naturally handles the sequence of behaviours within a foraging trip.
Additionally, by structuring the model in this way, we are able to develop
realistic simulations from the fitted model. We demonstrate our approach on
data from southern elephant seals (Mirounga leonina) tagged on Kerguelen Island
in the Southern Ocean. We discuss the differences between our 4-state model and
the widely used 2-state model, and the advantages and disadvantages of
employing a more complex model.
| arxiv topic:q-bio.QM stat.AP |
arxiv_dataset-78241610.07053 | Event reweighting with the NuWro neutrino interaction generator
hep-ex
Event reweighting has been implemented in the NuWro neutrino event generator
for a number of free theory parameters in the interaction model. Event
reweighting is a key analysis technique, used to efficiently study the effect
of neutrino interaction model uncertainties. This opens up the possibility for
NuWro to be used as a primary event generator by experimental analysis groups.
A preliminary model tuning to ANL and BNL data of quasi-elastic and single pion
production events was performed to validate the reweighting engine.
| arxiv topic:hep-ex |
arxiv_dataset-78251610.07153 | Convex Splitting Method for the Calculation of Transition States of
Energy Functional
math.NA
Among numerical methods for partial differential equations arising from
steepest descent dynamics of energy functionals (e.g., Allen-Cahn and
Cahn-Hilliard equations), the convex splitting method is well-known to maintain
unconditional energy stability for a large time step size. In this work, we
show how to use the convex splitting idea to find transition states, i.e.,
index-1 saddle points of the same energy functionals. Based on the iterative
minimization formulation (IMF) for saddle points (SIAM J. Numer. Anal., vol.
53, p1786, 2015), we introduce the convex splitting method to minimize the
auxiliary functional at each cycle of the IMF. We present a general principle
of constructing convex splitting forms for these auxiliary functionals and show
how to avoid solving nonlinear equations. The new numerical scheme based on the
convex splitting method allows for large time step sizes. The new methods are
tested for the one dimensional Ginzburg-Landau energy functional in the search
of the Allen-Cahn or Cahn-Hilliard types of transition states. We provide the
numerical results of transition states for the two dimensional
Landau-Brazovskii energy functional for diblock copolymers.
| arxiv topic:math.NA |
arxiv_dataset-78261610.07253 | Dual Ore's theorem for distributive intervals of small index
math.GR math.CO math.RT
This paper proves a dual version of a theorem of Oystein Ore for every
distributive interval of finite groups [H,G] of index |G:H|<9720, and for every
boolean interval of rank <7. It has applications to representation theory for
every finite group.
| arxiv topic:math.GR math.CO math.RT |
arxiv_dataset-78271610.07353 | Filter-based regularisation for impulse response modelling
cs.SY
In the last years, the success of kernel-based regularisation techniques in
solving impulse response modelling tasks has revived the interest on linear
system identification. In this work, an alternative perspective on the same
problem is introduced. Instead of relying on a Bayesian framework to include
assumptions about the system in the definition of the covariance matrix of the
parameters, here the prior knowledge is injected at the cost function level.
The key idea is to define the regularisation matrix as a filtering operation on
the parameters, which allows for a more intuitive formulation of the problem
from an engineering point of view. Moreover, this results in a unified
framework to model low-pass, band-pass and high-pass systems, and systems with
one or more resonances. The proposed filter-based approach outperforms the
existing regularisation method based on the TC and DC kernels, as illustrated
by means of Monte Carlo simulations on several linear modelling examples.
| arxiv topic:cs.SY |
arxiv_dataset-78281610.07453 | Hybrid Quantile Regression Estimation for Time Series Models with
Conditional Heteroscedasticity
stat.ME
Estimating conditional quantiles of financial time series is essential for
risk management and many other applications in finance. It is well-known that
financial time series display conditional heteroscedasticity. Among the large
number of conditional heteroscedastic models, the generalized autoregressive
conditional heteroscedastic (GARCH) process is the most popular and influential
one. So far, feasible quantile regression methods for this task have been
confined to a variant of the GARCH model, the linear GARCH model, owing to its
tractable conditional quantile structure. This paper considers the widely used
GARCH model. An easy-to-implement hybrid conditional quantile estimation
procedure is developed based on a simple albeit nontrivial transformation.
Asymptotic properties of the proposed estimator and statistics are derived,
which facilitate corresponding inferences. To approximate the asymptotic
distribution of the quantile regression estimator, we introduce a mixed
bootstrapping procedure, where a time-consuming optimization is replaced by a
sample averaging. Moreover, diagnostic tools based on the residual quantile
autocorrelation function are constructed to check the adequacy of the fitted
conditional quantiles. Simulation experiments are carried out to assess the
finite-sample performance of the proposed approach. The favorable performance
of the conditional quantile estimator and the usefulness of the inference tools
are further illustrated by an empirical application.
| arxiv topic:stat.ME |
arxiv_dataset-78291610.07553 | On the classification of definable ccc forcing notions
math.LO
We show that for a Suslin ccc forcing notion $\mathbb Q$ adding a Hechler
real, ``$\text{ZF}+\text{DC}_{\omega_1}+$all sets of reals are $I_{\mathbb
Q,\aleph_0}$-measurable'' implies the existence of an inner model with a
measurable cardinal. We also introduce a wide class of Suslin ccc forcing
notions which add a Hechler real, so that the above result applies to them.
| arxiv topic:math.LO |
arxiv_dataset-78301610.07653 | Synchrotron radiation and absence of linear polarization in the
colliding wind binary WR 146
astro-ph.HE astro-ph.SR
Several massive early-type binaries exhibit non-thermal emission which has
been attributed to synchrotron radiation from particles accelerated by
diffusive shock acceleration (DSA) in the wind-collision region (WCR). If the
magnetic field in the strong shocks is ordered, its component parallel to the
shock front should be enhanced, and the resultant synchrotron radiation would
be polarized. However, such polarization has never been measured. We performed
spatially-unresolved radio continuum observations of WR 146, a well known a
WC6+O8 system, at 5 cm and 20 cm with the Karl G. Jansky Very Large Array. No
linearly polarized radio emission was detected. The data constrain the
fractional linear polarization to less than 0.6% between 1 to 8 GHz. This is
compatible with a high level of turbulence and a dominant random component in
the magnetic field. In this case the relativistic particles could be produced
by turbulent magnetic reconnection (MR). In order for this scenario to satisfy
the required non-thermal energy budget, we find through numerical modeling that
the strength of the magnetic field in the WCR must be as high as ~150 mG.
However, if the magnetic field is ordered and DSA is ongoing, then a
combination of internal and external Faraday rotation could equally account for
the depolarization of the emission. It is not clear whether it is possible to
develop the high level of turbulence and strong magnetic fields required for
efficient MR in a long-period binary such as WR 146. This scenario might also
have trouble explaining the low-frequency cutoff in the spectrum. We therefore
favor a scenario where particles are accelerated through DSA and the
depolarization is produced by mechanisms other than a large ratio between
random to regular magnetic fields.
| arxiv topic:astro-ph.HE astro-ph.SR |
arxiv_dataset-78311610.07753 | A Novel Boundary Matching Algorithm for Video Temporal Error Concealment
cs.MM cs.CV
With the fast growth of communication networks, the video data transmission
from these networks is extremely vulnerable. Error concealment is a technique
to estimate the damaged data by employing the correctly received data at the
decoder. In this paper, an efficient boundary matching algorithm for estimating
damaged motion vectors (MVs) is proposed. The proposed algorithm performs error
concealment for each damaged macro block (MB) according to the list of
identified priority of each frame. It then uses a classic boundary matching
criterion or the proposed boundary matching criterion adaptively to identify
matching distortion in each boundary of candidate MB. Finally, the candidate MV
with minimum distortion is selected as an MV of damaged MB and the list of
priorities is updated. Experimental results show that the proposed algorithm
improves both objective and subjective qualities of reconstructed frames
without any significant increase in computational cost. The PSNR for test
sequences in some frames is increased about 4.7, 4.5, and 4.4 dB compared to
the classic boundary matching, directional boundary matching, and directional
temporal boundary matching algorithm, respectively.
| arxiv topic:cs.MM cs.CV |
arxiv_dataset-78321610.07853 | Competition of Dzyaloshinskii-Moriya and higher-order exchange
interactions in Rh/Fe atomic bilayers on Ir(111)
cond-mat.mes-hall
Using spin-polarized scanning tunneling microscopy and density functional
theory we demonstrate the occurrence of a novel type of noncollinear spin
structure in Rh/Fe atomic bilayers on Ir(111). We find that higher-order
exchange interactions depend sensitively on the stacking sequence. For
fcc-Rh/Fe/Ir(111) frustrated exchange interactions are dominant and lead to the
formation of a spin spiral ground state with a period of about 1.5 nm. For
hcp-Rh/Fe/Ir(111) higher-order exchange interactions favor a double-row wise
antiferromagnetic or "uudd" state. However, the Dzyaloshinskii- Moriya
interaction at the Fe/Ir interface leads to a small angle of about 4{\deg}
between adjacent magnetic moments resulting in a canted "uudd" ground state.
| arxiv topic:cond-mat.mes-hall |
arxiv_dataset-78331610.07953 | A reconnection-driven model of the hard X-ray loop-top source from flare
2004-Feb-26
astro-ph.SR
A compact X-class flare on 2004-Feb-26 showed a concentrated source of hard
X-rays at the tops of the flare's loops. This was analyzed in previous work
(Longcope et al. 2010), and interpreted as plasma heated and compressed by slow
magnetosonic shocks generated during post-reconnection retraction of the flux.
That work used analytic expressions from a thin flux tube (TFT) model, which
neglected many potentially important factors such as thermal conduction and
chromospheric evaporation. Here we use a numerical solution of the TFT
equations to produce a more comprehensive and accurate model of the same flare,
including those effects previously omitted. These simulations corroborate the
prior hypothesis that slow mode shocks persist well after the retraction has
ended, thus producing a compact, loop-top source instead of an elongated jet,
as steady reconnection models predict. Thermal conduction leads to densities
higher than analytic estimates had predicted, and evaporation enhances the
density still higher, but at lower temperatures. X-ray light curves and spectra
are synthesized by convolving the results from a single TFT simulation with the
rate at which flux is reconnected, as measured through motion of flare ribbons,
for example. These agree well with light curves observed by RHESSI and GOES and
spectra from RHESSI. An image created from a superposition of TFT model runs
resembles one produced from RHESSI observations. This suggests that the HXR
loop-top source, at least the one observed in this flare, could be the result
of slow magnetosonic shocks produced in fast reconnection models like
Petschek's.
| arxiv topic:astro-ph.SR |
arxiv_dataset-78341610.08053 | CAKE: The Coincidence Array for K600 Experiments
physics.ins-det nucl-ex
The combination of a magnetic spectrometer and ancillary detectors such as
silicon detectors is a powerful tool for the study of nuclear reactions and
nuclear structure. This paper discusses the recently commissioned silicon array
called the CAKE which is designed for use with the K600 magnetic spectrometer
at iThemba LABS.
| arxiv topic:physics.ins-det nucl-ex |
arxiv_dataset-78351610.08153 | On intersecting families of independent sets in trees
math.CO
A family of sets is intersecting if every pair of its sets intersect. A star
is a family with some element (a center) in each of its sets. The classical
1961 result of Erd\H{o}s, Ko, and Rado states that every intersecting family of
r-sets with $r\leq n/2$ has size at most that of a star. We say that graph G is
r-EKR if, among all intersecting families of independent r-sets of G, the
largest is attained by a star. In 2005 Holroyd and Talbot conjectured that
every graph G is r-EKR for all $1\leq r\leq \mu(G)/2$, where $\mu(G)$ is the
size of the smallest maximal independent set in G. We verified the conjecture
in 2011 for all chordal graphs containing an isolated vertex.
For graphs without isolated vertices it is difficult to determine the center
of the largest star, which is often necessary to prove that they are EKR. A
tree has the leaf property if its largest star occurs on one of its leaves. We
proved that every tree T has the leaf property when $r\leq 4$, and in 2017 Borg
and other authors gave examples of families of trees not having the leaf
property when $r\geq 5$. A split vertex in a tree is a vertex of degree at
least 3. A spider is a tree with exactly one split vertex. Here we prove that
all spiders have the leaf property for all $r\leq \alpha(G)$, where $\alpha(G)$
is the independence number of $G$, and we characterize which of its leaves are
maximum star centers. A pendant tree is one for which each of its split
vertices is adjacent to a leaf. Here we show that all pendant trees have the
leaf property for all $r\leq \alpha(G)$. We also consider pendant trees with
exactly two split vertices and provide partial results on the locations of
their maximum star centers.
| arxiv topic:math.CO |
arxiv_dataset-78361610.08253 | New Photometrically Variable Magnetic Chemically Peculiar Stars in the
ASAS-3 Archive
astro-ph.SR
The magnetic Ap or CP2 stars are natural atomic and magnetic laboratories and
ideal testing grounds for the evaluation of model atmospheres. CP2 stars
exhibiting photometric variability are traditionally referred to as alpha2
Canum Venaticorum (ACV) variables. Strictly periodic changes are observed in
the spectra and brightness of these stars, which allow the derivation of
rotational periods. Related to this group of objects are the He-weak (CP4) and
He-rich stars, some of which are also known to undergo brightness changes due
to rotational modulation. Increasing the sample size of known rotational
periods among CP2/4 stars is an important task, which will contribute to our
understanding of these objects and their evolution in time. We have compiled an
extensive target list of magnetic chemically peculiar (CP2/4) stars. In
addition to that, a systematic investigation of early-type (spectral types B/A)
variable stars of undetermined type in the International Variable Star Index of
the AAVSO (VSX) yielded additional ACV candidates, which were included in our
sample. We investigated our sample stars using publicly available observations
from the ASAS-3 archive. We were able to identify another 360 stars exhibiting
photometric variability in the accuracy limit of the ASAS-3 data, thereby
concluding our search for photometrically variable magnetic chemically peculiar
stars in the ASAS-3 archive. Summary data, folded light curves and, if
available, information from the literature are presented for all variable stars
of our sample, which is composed of 334 bona-fide ACV variables, 23 ACV
candidates and three eclipsing binary systems. In particular, we call attention
to HD 66051 (V414 Pup), which was identified as an eclipsing binary system
showing obvious rotational modulation of the light curve due to the presence of
an ACV variable in the system.
| arxiv topic:astro-ph.SR |
arxiv_dataset-78371610.08353 | Analogue of Pontryagin's maximum principle for multiple integrals
minimization problems
math.OC
The theorem like Pontryagin's maximum principle for multiple integrals is
proved. Unlike the usual maximum principle, the maximum should be taken not
over all matrices, but only on matrices of rank one. Examples are given.
| arxiv topic:math.OC |
arxiv_dataset-78381610.08453 | All silicon Josephson junctions
cond-mat.mes-hall cond-mat.supr-con
We have realised laser-doped all-silicon superconducting (S)/ normal metal
(N) bilayers of tunable thickness and dopant concentration. We observed a
strong reduction of the bilayers critical temperature when increasing the
normal metal thickness, a signature of the highly transparent S/N interface
associated to the epitaxial sharp laser doping profile. We extracted the
interface resistance by fitting with the linearised Usadel equations,
demonstrating a reduction of one order of magnitude from previous
superconductor/doped Si interfaces. In this well controlled crystalline system
we exploited the low resistance S/N interfaces to elaborate all-silicon lateral
SNS Josephson junctions with long range proximity effect. Their dc transport
properties, such as the critical and retrapping currents, could be well
understood in the diffusive regime. Furthermore, this work lead to the
estimation of important parameters in ultra-doped superconducting Si, such as
the Fermi velocity, the coherence length, or the electron-phonon coupling
constant, fundamental to conceive an all-silicon superconducting electronics.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-78391610.08553 | Josephson current signatures of the Majorana flat bands on the surface
of time-reversal-invariant Weyl and Dirac semimetals
cond-mat.supr-con cond-mat.mes-hall
A linear Josephson junction mediated by the surface states of a
time-reversal-invariant Weyl or Dirac semimetal localizes Majorana flat bands
protected by the time-reversal symmetry. We show that as a result, the
Josephson current exhibits a discontinuous jump at $\pi$ phase difference which
can serve as an experimental signature of the Majorana bands. The magnitude of
the jump scales proportionally to the junction width and the momentum space
distance between the Weyl nodes. It also exhibits a characteristic dependence
on the junction orientation. We demonstrate that the jump is robust against the
effects of non-zero temperature and weak non-magnetic disorder.
| arxiv topic:cond-mat.supr-con cond-mat.mes-hall |
arxiv_dataset-78401610.08653 | Detection of Very Low-Frequency Quasi-Periodic Oscillations in the 2015
Outburst of V404 Cygni
astro-ph.HE
In June 2015, the black hole X-ray binary (BHXRB) V404 Cygni went into
outburst for the first time since 1989. Here, we present a comprehensive search
for quasi-periodic oscillations (QPOs) of V404 Cygni during its recent
outburst, utilizing data from six instruments on board five different X-ray
missions: Swift/XRT, Fermi/GBM, Chandra/ACIS, INTEGRAL's IBIS/ISGRI and JEM-X,
and NuSTAR. We report the detection of a QPO at 18 mHz simultaneously with both
Fermi/GBM and Swift/XRT, another example of a rare but slowly growing new class
of mHz-QPOs in BHXRBs linked to sources with a high orbital inclination.
Additionally, we find a duo of QPOs in a Chandra/ACIS observation at 73 mHz and
1.03 Hz, as well as a QPO at 136 mHz in a single Swift/XRT observation that can
be interpreted as standard Type-C QPOs. Aside from the detected QPOs, there is
significant structure in the broadband power, with a strong feature observable
in the Chandra observations between 0.1 and 1 Hz. We discuss our results in the
context of current models for QPO formation.
| arxiv topic:astro-ph.HE |
arxiv_dataset-78411610.08753 | New scenarios for hard-core interactions in a hadron resonance gas
nucl-th hep-ph
The equation of state of a baryon-symmetric hadronic matter with hard-sphere
interactions is studied. It is assumed that mesons are point-like, but baryons
and antibaryons have the same hard-core radius rB. Three possibilities are
considered: 1) the baryon-baryon and antibaryon-baryon interactions are the
same; 2) baryons do not interact with antibaryons; 3) the baryon-antibaryon and
meson-(anti)baryon interactions are negligible. By choosing the parameter
rB=0.3-0.6 fm, we calculate the nucleon to pion ratio as a function of
temperature and perform the fit of hadron yields measured in central Pb+Pb
collisions at the bombarding energy Ecm=2.76 TeV per nucleon pair. New
nontrivial effects in the interacting hadron resonance gas at temperatures
150-200 MeV are found.
| arxiv topic:nucl-th hep-ph |
arxiv_dataset-78421610.08853 | Personalized Risk Scoring for Critical Care Prognosis using Mixtures of
Gaussian Processes
cs.AI
Objective: In this paper, we develop a personalized real-time risk scoring
algorithm that provides timely and granular assessments for the clinical acuity
of ward patients based on their (temporal) lab tests and vital signs; the
proposed risk scoring system ensures timely intensive care unit (ICU)
admissions for clinically deteriorating patients. Methods: The risk scoring
system learns a set of latent patient subtypes from the offline electronic
health record data, and trains a mixture of Gaussian Process (GP) experts,
where each expert models the physiological data streams associated with a
specific patient subtype. Transfer learning techniques are used to learn the
relationship between a patient's latent subtype and her static admission
information (e.g. age, gender, transfer status, ICD-9 codes, etc). Results:
Experiments conducted on data from a heterogeneous cohort of 6,321 patients
admitted to Ronald Reagan UCLA medical center show that our risk score
significantly and consistently outperforms the currently deployed risk scores,
such as the Rothman index, MEWS, APACHE and SOFA scores, in terms of
timeliness, true positive rate (TPR), and positive predictive value (PPV).
Conclusion: Our results reflect the importance of adopting the concepts of
personalized medicine in critical care settings; significant accuracy and
timeliness gains can be achieved by accounting for the patients' heterogeneity.
Significance: The proposed risk scoring methodology can confer huge clinical
and social benefits on more than 200,000 critically ill inpatient who exhibit
cardiac arrests in the US every year.
| arxiv topic:cs.AI |
arxiv_dataset-78431610.08953 | Einstein--Weyl Spaces and Near-Horizon Geometry
hep-th gr-qc
We show that a class of solutions of minimal supergravity in five dimensions
is given by lifts of three--dimensional Einstein--Weyl structures of hyper-CR
type. We characterise this class as most general near--horizon limits of
supersymmetric solutions to the five--dimensional theory. In particular, we
deduce that a compact spatial section of a horizon can only be a Berger sphere,
a product metric on $S^1\times S^2$ or a flat three-torus. We then consider the
problem of reconstructing all supersymmetric solutions from a given
near--horizon geometry. By exploiting the ellipticity of the linearised field
equations we demonstrate that the moduli space of transverse infinitesimal
deformations of a near--horizon geometry is finite--dimensional.
| arxiv topic:hep-th gr-qc |
arxiv_dataset-78441610.09053 | Higher-order nonclassical effects in fluctuating-loss channels
quant-ph
We study the evolution of higher-order nonclassicality and entanglement
criteria in atmospheric fluctuating-loss channels. By formulating input-output
relations for the matrix of moments, we investigate the influence of such
channels on the corresponding quantumness criteria. This generalization of our
previous work on Gaussian entanglement [M. Bohmann et al., Phys. Rev. A 94,
010302(R) (2016)] not only exploits second-order-based scenarios, but it also
provides a detailed investigation of nonclassicality and entanglement in
non-Gaussian and multimode radiation fields undergoing a fluctuating
attenuation. That is, various examples of criteria and states are studied in
detail, unexpected effects, e.g., the dependency of the squeezing transfer on
the coherent displacement, are discovered, and it is demonstrated that
non-Gaussian entanglement can be more robust against atmospheric losses than
Gaussian one. Additionally, we propose a detection scheme for measuring the
considered moments after propagation through the atmosphere. Therefore, our
results may help to develop, improve, and optimize non-Gaussian sources of
quantum light for applications in free-space quantum communication.
| arxiv topic:quant-ph |
arxiv_dataset-78451610.09153 | Observation of the Bloch-Siegert shift in a driven quantum-to-classical
transition
cond-mat.mes-hall quant-ph
We show that the counter-rotating terms of the dispersive qubit-cavity Rabi
model can produce relatively large and nonmonotonic Bloch-Siegert shifts in the
cavity frequency as the system is driven through a quantum-to-classical
transition. Using a weak microwave probe tone, we demonstrate experimentally
this effect by monitoring the resonance frequency of a microwave cavity coupled
to a transmon and driven by a microwave field with varying power. In the weakly
driven regime (quantum phase), the Bloch-Siegert shift appears as a small
constant frequency shift, while for strong drive (classical phase) it presents
an oscillatory behaviour as a function of the number of photons in the cavity.
The experimental results are in agreement with numerical simulations based on
the quasienergy spectrum.
| arxiv topic:cond-mat.mes-hall quant-ph |
arxiv_dataset-78461610.09253 | Supporting novel biomedical research via multilayer collaboration
networks
cs.SI q-bio.BM q-bio.MN q-bio.QM
The value of research containing novel combinations of molecules can be seen
in many innovative and award-winning research programs. Despite calls to use
innovative approaches to address common diseases, an increasing majority of
research funding goes toward "safe" incremental research. Counteracting this
trend by nurturing novel and potentially transformative scientific research is
challenging, it must be supported in competition with established research
programs. Therefore, we propose a tool that helps to resolve the tension
between safe but fundable research vs. high-risk but potentially
transformational research. It does this by identifying hidden overlapping
interest around novel molecular research topics. Specifically, it identifies
paths of molecular interactions that connect research topics and hypotheses
that would not typically be associated, as the basis for scientific
collaboration. Because these collaborations are related to the scientists'
present trajectory, they are low risk and can be initiated rapidly. Unlike most
incremental steps, these collaborations have the potential for leaps in
understanding, as they reposition research for novel disease applications. We
demonstrate the use of this tool to identify scientists who could contribute to
understanding the cellular role of genes with novel associations with
Alzheimer's disease, which have not been thoroughly characterized, in part due
to the funding emphasis on established research.
| arxiv topic:cs.SI q-bio.BM q-bio.MN q-bio.QM |
arxiv_dataset-78471610.09353 | Eigenvalue spectra of large correlated random matrices
cond-mat.dis-nn
Using the diagrammatic method, we derive a set of self-consistent equations
that describe eigenvalue distributions of large correlated asymmetric random
matrices. The matrix elements can have different variances and be correlated
with each other. The analytical results are confirmed by numerical simulations.
The results have implications for the dynamics of neural and other biological
networks where plasticity induces correlations in the connection strengths
within the network. We find that the presence of correlations can have a major
impact on network stability.
| arxiv topic:cond-mat.dis-nn |
arxiv_dataset-78481610.09453 | Degrees of Freedom in Wireless Interference Networks with Cooperative
Transmission and Backhaul Load Constraints
cs.IT math.IT
Degrees of freedom (DoF) gains are studied in wireless networks with
cooperative transmission under a backhaul load constraint that limits the
average number of messages that can be delivered from a centralized controller
to base station transmitters. The backhaul load is defined as the sum of all
the messages available at all the transmitters per channel use, normalized by
the number of users. For Wyner's linear interference network, where each
transmitter is connected to the receiver having the same index as well as one
succeeding receiver, the per user DoF is characterized and the optimal scheme
is presented. Furthermore, it is shown that the optimal assignment of messages
to transmitters is asymmetric and satisfies a local cooperation constraint, and
that the optimal coding scheme relies only on one-shot cooperative zero-forcing
transmit beamforming. Using insights from the analysis of Wyner's linear
interference network, the results are extended to the more practical hexagonal
sectored cellular network, and coding schemes based on cooperative zero-forcing
are shown to deliver significant DoF gains. It is established that by allowing
for cooperative transmission and a flexible message assignment that is
constrained only by an average backhaul load, one can deliver the rate gains
promised by information-theoretic upper bounds with practical one-shot schemes
that incur little or no additional load on the backhaul. Finally, useful upper
bounds on the per user DoF for schemes based on cooperative zero-forcing are
presented for lower values of the average backhaul load constraint, and an
optimization framework is formulated for the general converse problem.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-78491610.09553 | Recovering Finite Parametric Distributions and Functions Using the
Spherical Mean Transform
math.AP
The aim of the article is to recover a certain type of finite parametric
distributions and functions using their spherical mean transform which is given
on a certain family of spheres whose centers belong to a finite set $\Gamma$.
For this, we show how the problem of reconstruction can be converted to a
Prony's type system of equations whose regularity is guaranteed by the
assumption that the points in the set $\Gamma$ are in general position. By
solving the corresponding Prony's system we can extract the set of parameters
which define the corresponding function or distribution.
| arxiv topic:math.AP |
arxiv_dataset-78501610.09653 | New bounds for the Moser-Tardos distribution
math.CO cs.DM math.PR
The Lovasz Local Lemma (LLL) is a probabilistic tool which has been used to
show the existence of a variety of combinatorial structures with good "local"
properties. The "LLL-distribution" can be used to show that the resulting
structures have good global properties in expectation.
The simplest, variable-based setting of the LLL was covered by the seminal
algorithm of Moser & Tardos (2010). This has since been extended to other
probability spaces including random permutations. One can similarly define an
"MT-distribution" for these algorithms, that is, the distribution of the
configuration they produce. Haeupler et al. (2011) showed bounds on the
MT-distribution which essentially match the LLL-distribution for the
variable-assignment setting; Harris & Srinivasan showed similar results for the
permutation setting.
In this work, we show new bounds on the MT-distribution which are
significantly stronger than those known to hold for the LLL-distribution. In
the variable-assignment setting, we show a tighter bound on the probability of
a disjunctive event or singleton event. As a consequence, in $k$-SAT instances
with bounded variable occurrence, the MT-distribution satisfies an
$\epsilon$-approximate independence condition asymptotically stronger than the
LLL-distribution. We use this to show a nearly tight bound on the minimum
implicate size of a CNF boolean formula. Another noteworthy application is
constructing independent transversals which avoid a given subset of vertices;
this provides a constructive analogue to a result of Rabern (2014).
In the permutation LLL setting, we show a new type of bound which is similar
to the cluster-expansion LLL criterion of Bissacot et al. (2011), but is
stronger and takes advantage of the extra structure in permutations. We
illustrate with improved bounds on weighted Latin transversals and partial
Latin transversals.
| arxiv topic:math.CO cs.DM math.PR |
arxiv_dataset-78511610.09753 | Ricci flow from spaces with isolated conical singularities
math.DG
Let $(M,g_0)$ be a compact $n$-dimensional Riemannian manifold with a finite
number of singular points, where the metric is asymptotic to a non-negatively
curved cone over $(\mathbb{S}^{n-1},g)$. We show that there exists a smooth
Ricci flow starting from such a metric with curvature decaying like C/t. The
initial metric is attained in Gromov-Hausdorff distance and smoothly away from
the singular points. In the case that the initial manifold has isolated
singularities asymptotic to a non-negatively curved cone over
$(\mathbb{S}^{n-1}/\Gamma,g)$, where $\Gamma$ acts freely and properly
discontinuously, we extend the above result by showing that starting from such
an initial condition there exists a smooth Ricci flow with isolated orbifold
singularities.
| arxiv topic:math.DG |
arxiv_dataset-78521610.09853 | Delayed versus accelerated quarkonium formation in a magnetic field
hep-ph nucl-ex nucl-th
Formation time of heavy quarkonia in a homogeneous magnetic field is analyzed
by using a phenomenological ansatz of the vector current correlator. Because
the existence of a magnetic field mixes vector quarkonia ($J/\psi$,
$\psi^\prime$) and their pseudoscalar partners ($\eta_c$, $\eta_c^\prime$), the
properties of the quarkonia can be modified through such a spin mixing. This
means that the formation time of quarkonia is also changed by the magnetic
field. We show the formation time of vector quarkonia is delayed by an
idealized constant magnetic field, where the formation time of the excited
state becomes longer than that of the ground state. As a more realistic
situation in heavy-ion collisions, effects by a time-dependent magnetic field
are also discussed, where delayed formation of $J/\psi$ and $\psi^\prime$ and
very early formation of $\eta_c$ and $\eta_c^\prime$ are found.
| arxiv topic:hep-ph nucl-ex nucl-th |
arxiv_dataset-78531610.09953 | Non-perturbative gluon-hadron inputs for all available forms of QCD
factorization
hep-ph
Description of hadronic reactions at high energies is conventionally done on
basis of QCD factoriza- tion so that factorization convolutions involve
non-perturbative inputs mimicking non-perturbative contributions and
perturbative evolution of those inputs. We construct the inputs for the gluon-
hadron scattering amplitudes in the forward kinematics and, using the Optical
theorem, convert them into inputs for gluon distributions in the both polarized
and unpolarized hadrons. Firstly, we derive general mathematical criteria which
any model for the inputs should obey and then suggest a Resonance Model
satisfying those criteria. This model is inspired by a simple observation:
after emitting an active parton off the hadron, the remaining ensemble of
spectators becomes unstable and therefore it can be described through factors
of the resonance type. Exploiting Resonance Model, we obtain non-perturbative
inputs for gluon distributions in unpolarized and polarized hadrons for all
available forms of QCD factorization: Basic, KT - and Collinear Factorizations.
We compare the obtained inputs to the inputs available in the literature.
| arxiv topic:hep-ph |
arxiv_dataset-78541610.10053 | Benchmarking the Multi-dimensional Stellar Implicit Code MUSIC
astro-ph.IM astro-ph.SR
We present the results of a numerical benchmark study for the
MUlti-dimensional Stellar Implicit Code (MUSIC) based on widely applicable two-
and three-dimensional compressible hydrodynamics problems relevant to stellar
interiors. MUSIC is an implicit large eddy simulation code that uses implicit
time integration, implemented as a Jacobian-free Newton Krylov method. A
physics based preconditioning technique which can be adjusted to target varying
physics is used to improve the performance of the solver. The problems used for
this benchmark study include the Rayleigh-Taylor and Kelvin-Helmholtz
instabilities, and the decay of the Taylor-Green vortex. Additionally we show a
test of hydrostatic equilibrium, in a stellar environment which is dominated by
radiative effects. In this setting the flexibility of the preconditioning
technique is demonstrated. This work aims to bridge the gap between the
hydrodynamic test problems typically used during development of numerical
methods and the complex flows of stellar interiors. A series of
multi-dimensional tests are performed and analysed. Each of these test cases is
analysed with a simple, scalar diagnostic, with the aim of enabling direct code
comparisons. As the tests performed do not have analytic solutions we verify
MUSIC by comparing to established codes including ATHENA and the PENCIL code.
MUSIC is able to both reproduce behaviour from established and widely-used
codes as well as results expected from theoretical predictions. This
benchmarking study concludes a series of papers describing the development of
the MUSIC code and provides confidence in the future applications.
| arxiv topic:astro-ph.IM astro-ph.SR |
arxiv_dataset-78551611.00053 | Photon echo in exciton-plasmon nanomaterials: a time-dependent signature
of strong coupling
cond-mat.mes-hall physics.optics
We investigate the dynamics of photon echo exhibited by exciton-plasmon
systems under strong coupling conditions. Using a self-consistent model based
on coupled Maxwell-Bloch equations we investigate femtosecond time dynamics of
ensembles of interacting molecules optically coupled to surface plasmon
supporting materials. It is shown that observed photon echoes under two pulse
pump-probe sequence are highly dependent on various material parameters such as
molecular concentration and periodicity. Simulations of photon echoes in
exciton-plasmon materials reveal a unique signature of the strong
exciton-plasmon coupling, namely a double-peak structure in spectra of recorded
echo signals. This phenomenon is shown to be related to hybrid states (upper
and lower polaritons) in exciton-plasmon systems under strong coupling
conditions. It is also demonstrated that the double-peak echo is highly
sensitive to mild deviations of the coupling from resonant conditions making it
a great tool for ultrafast probes.
| arxiv topic:cond-mat.mes-hall physics.optics |
arxiv_dataset-78561611.00153 | Discovery of the secondary eclipse of HAT-P-11 b
astro-ph.EP astro-ph.SR
We report the detection of the secondary eclipse of HAT-P-11 b, a
Neptune-sized planet orbiting an active K4 dwarf. Using all available
short-cadence data of the Kepler mission, we derive refined planetary ephemeris
increasing their precision by more than an order of magnitude. Our simultaneous
primary and secondary transit modeling results in improved transit and orbital
parameters. In particular, the precise timing of the secondary eclipse allows
to pin down the orbital eccentricity to $0.26459_{-0.00048}^{+0.00069}$. The
secondary eclipse depth of $6.09_{-1.11}^{+1.12}$ ppm corresponds to a
$5.5\sigma$ detection and results in a geometric albedo of $0.39\pm0.07$ for
HAT-P-11 b, close to Neptune's value, which may indicate further resemblances
between these two bodies. Due to the substantial orbital eccentricity, the
planetary equilibrium temperature is expected to change significantly with
orbital position and ought to vary between $630^\circ$ K and $950^\circ$ K,
depending on the details of heat redistribution in the atmosphere of HAT-P-11
b.
| arxiv topic:astro-ph.EP astro-ph.SR |
arxiv_dataset-78571611.00253 | Photometry of some neglected bright cataclysmic variables and candidates
astro-ph.SR
As part of an effort to better characterize bright cataclysmic variables
(CVs) which have received little attention in the past light curves of four
confirmed systems (CZ Aql, BO Cet, V380 Oph and EF Tuc) and one candidate (Lib
3) are analyzed. For none of these stars time resolved photometry has been
published previously. While no variability was found in the case of Lib 3,
which thus cannot be confirmed as a CV, the light curves of all other targets
are dominated by strong flickering. Modulations on hourly time scales
superimposed on the flickering can probably be related to orbital variations in
BO Cet and V380 Oph, but not in CZ Aql and EF Tuc. Variations on the time scale
of 10 minutes in CZ Aql, while not yet constituting convincing evidence,
together with previous suspicions of a magnetically channeled accretion flow
may point at an intermediate polar nature of this star. Some properties of the
flickering are quantified in an effort to enlarge the data base for future
comparative flickering studies in CVs and to refine the classification of the
target stars.
| arxiv topic:astro-ph.SR |
arxiv_dataset-78581611.00353 | Thermoelectric properties of a ferromagnet-superconductor hybrid
junction: Role of interfacial Rashba spin-orbit interaction
cond-mat.mes-hall cond-mat.supr-con
We investigate thermoelectric properties of a ferromagnet-superconductor
hybrid structure with Rashba spin-orbit interaction and delta function
potential barrier at the interfacial layer. The exponential rise of thermal
conductance with temperature manifests a cross-over temperature scale
separating two opposite behaviors of it with the change of polarization in the
ferromagnet whereas the inclusion of interfacial Rashba spin-orbit field
results in a non-monotonic behavior of it with the strength of Rashba field. We
employ scattering matrix approach to determine the amplitudes of all the
scattering processes possible at the interface to explain the thermoelectric
properties of the device. We examine Seebeck effect and show that higher
thermopower can be achieved when the polarization of the ferromagnet tends
towards the half-metallic limit. It can be enhanced even for lower polarization
in presence of the finite potential barrier. In presence of interfacial Rashba
spin-orbit interaction, Seebeck coefficient rises with the increase of barrier
strength and polarization at weak or moderate interfacial Rashba field. From
the application perspective, we compute the figure of merit and show that
$zT\sim 4-5$ with higher polarization of the ferromagnet both in absence and
presence of weak or moderate Rashba spin-orbit interaction along with the
scalar potential barrier.
| arxiv topic:cond-mat.mes-hall cond-mat.supr-con |
arxiv_dataset-78591611.00453 | Directional Training and Fast Sector-based Processing Schemes for mmWave
Channels
cs.IT math.IT
We consider a single-cell scenario involving a single base station (BS) with
a massive array serving multi-antenna terminals in the downlink of a mmWave
channel. We present a class of multiuser user MIMO schemes, which rely on
uplink training from the user terminals, and on uplink/downlink channel
reciprocity. The BS employs virtual sector-based processing according to which,
user-channel estimation and data transmission are performed in parallel over
non-overlapping angular sectors. The uplink training schemes we consider are
non-orthogonal, that is, we allow multiple users to transmit pilots on the same
pilot dimension (thereby potentially interfering with one another). Elementary
processing allows each sector to determine the subset of user channels that can
be resolved on the sector (effectively pilot contamination free) and, thus, the
subset of users that can be served by the sector. This allows resolving
multiple users on the same pilot dimension at different sectors, thereby
increasing the overall multiplexing gains of the system. Our analysis and
simulations reveal that, by using appropriately designed directional training
beams at the user terminals, the sector-based transmission schemes we present
can yield substantial spatial multiplexing and ergodic user-rates improvements
with respect to their orthogonal-training counterparts.
| arxiv topic:cs.IT math.IT |
arxiv_dataset-78601611.00553 | Rational curves on smooth hypersurfaces of low degree
math.AG math.NT
We study the family of rational curves on arbitrary smooth hypersurfaces of
low degree using tools from analytic number theory.
| arxiv topic:math.AG math.NT |
arxiv_dataset-78611611.00653 | Convexity of power functions and bilinear embedding for divergence-form
operators with complex coefficients
math.CA math.FA
We introduce a condition on accretive matrix functions, called
$p$-ellipticity, and discuss its applications to the $L^p$ theory of elliptic
PDE with complex coefficients. Our examples are:
(i) generalized convexity of power functions (Bellman functions),
(ii) dimension-free bilinear embeddings,
(iii) $L^p$-contractivity of semigroups and
(iv) holomorphic functional calculus.
Recent work by Dindo\v{s} and Pipher (arXiv:1612.01568v3) established close
ties between $p$-ellipticity and
(v) regularity theory of elliptic PDE with complex coefficients.
The $p$-ellipticity condition arises from studying uniform positivity of a
quadratic form associated with the matrix in question on one hand, and the
Hessian of a power function on the other. Our results regarding contractivity
extend earlier theorems by Cialdea and Maz'ya.
| arxiv topic:math.CA math.FA |
arxiv_dataset-78621611.00753 | Random spin distributions and the diffusion equation
quant-ph
We show that the probability distribution corresponding to a fully random
tracial state of a system of spin-S particles satisfies a diffusion-like
equation. The diffusion coefficient turns out to be equal to $S(S+1)/6$, where
$S$ is the magnitude of the spin of each particle. We also present a
bosonization scheme for the lowering and raising total spin operators.
| arxiv topic:quant-ph |
arxiv_dataset-78631611.00853 | Scale Holography
hep-th
We present a new correspondence between a d-dimensional dynamical system and
a whole family of (d+1)-dimensional systems. This new scale-holographic
relation is built by the explicit introduction of a dimensionful constant which
determines the size of the additional dimension. Scale holography is
particularly useful for studying non-local theories, since the equivalent dual
system on the higher dimensional manifold can be made to be local, as we
illustrate with the specific example of the p-adic string.
| arxiv topic:hep-th |
arxiv_dataset-78641611.00953 | High-dimensional regression over disease subgroups
stat.AP stat.ML
We consider high-dimensional regression over subgroups of observations. Our
work is motivated by biomedical problems, where disease subtypes, for example,
may differ with respect to underlying regression models, but sample sizes at
the subgroup-level may be limited. We focus on the case in which
subgroup-specific models may be expected to be similar but not necessarily
identical. Our approach is to treat subgroups as related problem instances and
jointly estimate subgroup-specific regression coefficients. This is done in a
penalized framework, combining an $\ell_1$ term with an additional term that
penalizes differences between subgroup-specific coefficients. This gives
solutions that are globally sparse but that allow information-sharing between
the subgroups. We present algorithms for estimation and empirical results on
simulated data and using Alzheimer's disease, amyotrophic lateral sclerosis and
cancer datasets. These examples demonstrate the gains our approach can offer in
terms of prediction and the ability to estimate subgroup-specific sparsity
patterns.
| arxiv topic:stat.AP stat.ML |
arxiv_dataset-78651611.01053 | Coherent Order Parameter Oscillations in the Ground State of the
Excitonic Insulator Ta2NiSe5
cond-mat.str-el
The excitonic insulator is an intriguing electronic phase of quasi-condensed
excitons. A prominent candidate is the small bandgap semiconductor Ta2NiSe5, in
which excitons are believed to undergo a BEC-like transition. But experimental
evidence for the existence of a coherent condensate in this material is still
missing. A direct fingerprint of such a state would be the observation of its
collective modes, which are equivalent to the Higgs- and Goldstone-modes in
superconductors. Here we report evidence for the existence of a coherent
amplitude response in the excitonic insulator phase of Ta2NiSe5. Using
non-linear excitations with short laser pulses we identify a phonon-coupled
state of the condensate that can be understood as a coupling of its electronic
Higgs-mode to a low frequency phonon. The Higgs-mode contribution substantiates
the picture of an electronically driven phase transition and characterizes the
transient order parameter of the excitonic insulator as a function of
temperature and excitation density.
| arxiv topic:cond-mat.str-el |
arxiv_dataset-78661611.01153 | On Perfectness of Intersection Graph of Ideals of $\mathbb{Z}_n$
math.GM
In this paper, we characterize the positive integers $n$ for which
intersection graph of ideals of $\mathbb{Z}_n$ is perfect.
| arxiv topic:math.GM |
arxiv_dataset-78671611.01253 | Plancherel distribution of Satake parameters of Maass cusp forms on
$GL_3$
math.NT
We prove an equidistribution result for the Satake parameters of Maass cusp
forms on $GL_3$ with respect to the $p$-adic Plancherel measure by using an
application of the Kuznetsov trace formula. The techniques developed in this
paper deal with the removal of arithmetic weight $L(1,F,Ad)^{-1}$ in the
Kuznetsov trace formula on $GL_3$.
| arxiv topic:math.NT |
arxiv_dataset-78681611.01353 | Information Dropout: Learning Optimal Representations Through Noisy
Computation
stat.ML cs.LG stat.CO
The cross-entropy loss commonly used in deep learning is closely related to
the defining properties of optimal representations, but does not enforce some
of the key properties. We show that this can be solved by adding a
regularization term, which is in turn related to injecting multiplicative noise
in the activations of a Deep Neural Network, a special case of which is the
common practice of dropout. We show that our regularized loss function can be
efficiently minimized using Information Dropout, a generalization of dropout
rooted in information theoretic principles that automatically adapts to the
data and can better exploit architectures of limited capacity. When the task is
the reconstruction of the input, we show that our loss function yields a
Variational Autoencoder as a special case, thus providing a link between
representation learning, information theory and variational inference. Finally,
we prove that we can promote the creation of disentangled representations
simply by enforcing a factorized prior, a fact that has been observed
empirically in recent work. Our experiments validate the theoretical intuitions
behind our method, and we find that information dropout achieves a comparable
or better generalization performance than binary dropout, especially on smaller
models, since it can automatically adapt the noise to the structure of the
network, as well as to the test sample.
| arxiv topic:stat.ML cs.LG stat.CO |
arxiv_dataset-78691611.01453 | The skyrmion switch: turning magnetic skyrmion bubbles on and off with
an electric field
cond-mat.mtrl-sci
Nanoscale magnetic skyrmions are considered as potential information carriers
for future spintronics memory and logic devices. Such applications will require
the control of their local creation and annihilation, which involves so far
solutions that are either energy consuming or difficult to integrate. Here we
demonstrate the control of skyrmion bubbles nucleation and annihilation using
electric field gating, an easily integrable and potentially energetically
efficient solution. We present a detailed stability diagram of the skyrmion
bubbles in a Pt/Co/oxide trilayer and show that their stability can be
controlled via an applied electric field. An analytical bubble model, with the
Dzyaloshinskii-Moriya interaction imbedded in the domain wall energy, account
for the observed electrical skyrmion switching effect. This allows us to unveil
the origin of the electrical control of skyrmions stability and to show that
both magnetic dipolar interaction and the Dzyaloshinskii-Moriya interaction
play an important role in the skyrmion bubble stabilization.
| arxiv topic:cond-mat.mtrl-sci |
arxiv_dataset-78701611.01553 | QBF Solving by Counterexample-guided Expansion
cs.LO cs.AI
We introduce a novel generalization of Counterexample-Guided Inductive
Synthesis (CEGIS) and instantiate it to yield a novel, competitive algorithm
for solving Quantified Boolean Formulas (QBF). Current QBF solvers based on
counterexample-guided expansion use a recursive approach which scales poorly
with the number of quantifier alternations. Our generalization of CEGIS removes
the need for this recursive approach, and we instantiate it to yield a simple
and efficient algorithm for QBF solving. Lastly, this research is supported by
a competitive, though straightforward, implementation of the algorithm, making
it possible to study the practical impact of our algorithm design decisions,
along with various optimizations.
| arxiv topic:cs.LO cs.AI |
arxiv_dataset-78711611.01653 | Perturbative QCD and beyond: azimuthal angle correlations in
deuteron-deuteron scattering from Bose-Einstein correlations
hep-ph
In this paper, we found within the framework of perturbative QCD, that in
deuteron-deuteron scattering the Bose-Einstein correlations due to two parton
showers production, induce azimuthal angle correlations, with three correlation
lengths: the size of the deuteron ($R_D$), the proton radius ($R_N$), and the
size of the BFKL Pomeron which, is closely related to the saturation momentum
($R_c \sim 1/Q_s$). These correlations are independent of the values of
rapidities of the produced gluons (long range rapidity correlations), for large
rapidities ($\bas |y_1 - y_2| \geq 1$), and have no symmetry with respect to
$\phi \to \pi - \phi$ ($ \vec{p}_{T1} \to - \vec{p}_{T1}$). Therefore, they
give rise to $v_n$ for all values of $n$, not only even values. The
contributions with the correlation length $R_D$ and $R_N$ crucially depend on
the non-perturbative contributions, and to obtain estimates of their values,
requiries a lot of modeling, while the correlations with $R_c \sim 1/Q_s$ have
a perturbative QCD origin, and can be estimated in the ColorGlass Condensate
(CGC) approach.
| arxiv topic:hep-ph |
arxiv_dataset-78721611.01753 | Universe opacity and EBL
astro-ph.GA astro-ph.CO
The observed extragalactic background light (EBL) is affected by light
attenuation due to absorption of light by galactic and intergalactic dust in
the Universe. Even galactic opacity of 10-20 percent and minute universe
intergalactic opacity of $0.01\,\mathrm{mag}\,h\,\mathrm{Gpc}^{-1}$ at the
local Universe have a significant impact on the EBL because obscuration of
galaxies and density of intergalactic dust increase with redshift as
$\left(1+z\right)^3$. Consequently, intergalactic opacity increases and the
Universe becomes considerably opaque at $z > 3$. Adopting realistic values for
galactic and intergalactic opacity, the estimates of the EBL for the expanding
dusty universe are close to observations. The luminosity density evolution fits
well measurements. The model reproduces a steep increase of the luminosity
density at $z<2$, its maximum at $z=2-3$, and its decrease at higher redshifts.
The increase of the luminosity density at low $z$ is not produced by the
evolution of the star formation rate but by the fact that the Universe occupied
a smaller volume in previous epochs. The decline of the luminosity density at
high $z$ originates in the opacity of the Universe. The calculated bolometric
EBL ranges from 100 to 200 $\mathrm{n W m}^{-2}\mathrm{sr}^{-1}$ and is within
the limits of 40 and 200 $\mathrm{n W m}^{-2}\mathrm{sr}^{-1}$ of current EBL
observations. The model predicts 98\% of the EBL coming from radiation of
galaxies at $z<3.5$. Accounting for light extinction by intergalactic dust
implies that the Universe was probably more opaque than dark for $z>3.5$.
| arxiv topic:astro-ph.GA astro-ph.CO |
arxiv_dataset-78731611.01853 | MTS Sketch for Accurate Estimation of Set-Expression Cardinalities from
Small Samples
cs.DB cs.DS
Sketch-based streaming algorithms allow efficient processing of big data.
These algorithms use small fixed-size storage to store a summary ("sketch") of
the input data, and use probabilistic algorithms to estimate the desired
quantity. However, in many real-world applications it is impractical to collect
and process the entire data stream, the common practice is thus to sample and
process only a small part of it. While sampling is crucial for handling massive
data sets, it may reduce accuracy. In this paper we present a new framework
that can accurately estimate the cardinality of any set expression between any
number of streams using only a small sample of each stream. The proposed
framework consists of a new sketch, called Maximal-Term with Subsample (MTS),
and a family of algorithms that use this sketch. An example of a possible query
that can be efficiently answered using the proposed sketch is, How many
distinct tuples appear in tables $T_1$ and $T_2$, but not in $T_3$? The
algorithms presented in this paper answer such queries accurately, processing
only a small sample of the tuples in each table and using a constant amount of
memory. Such estimations are useful for the optimization of queries over very
large database systems. We show that all our algorithms are unbiased, and we
analyze their asymptotic variance.
| arxiv topic:cs.DB cs.DS |
arxiv_dataset-78741611.01953 | The [Ne III] Jet of DG Tau and its Ionization Scenarios
astro-ph.SR astro-ph.GA
Forbidden neon emission from jets of low-mass young stars can be used to
probe the underlying high-energy processes in these systems. We analyze spectra
of the jet of DG Tau obtained with the Very Large Telescope/X-Shooter
spectrograph in 2010. [Ne III] $\lambda$3869 is clearly detected in the
innermost 3" microjet and the outer knot located at $\sim$6".5. The velocity
structure of the inner microjet can be decomposed into the low-velocity
component (LVC) at $\sim -70$ km/s and the high-velocity component (HVC) at
$\sim -180$ km/s. Based on the observed [Ne III] flux and its spatial extent,
we suggest the origins of the [Ne III] emission regions and their relation with
known X-ray sources along the jet. The flares from the hard X-ray source close
to the star may be the main ionization source of the innermost microjet. The
fainter soft X-ray source at 0".2 from the star may provide sufficient heating
to help to sustain the ionization fraction against the recombination in the
flow. The outer knot may be reionized by shocks faster than 100 km/s such that
[Ne III] emission reappears and that the soft X-ray emission at 5".5 is
produced. Velocity decomposition of the archival Hubble Space Telescope spectra
obtained in 1999 shows that the HVC had been faster, with a velocity centroid
of $\sim -260$ km/s. Such a decrease in velocity may potentially be explained
by the expansion of the stellar magnetosphere, changing the truncation radius
and thus the launching speed of the jet. The energy released by magnetic
reconnections during relaxation of the transition can heat the gas up to
several tens of megakelvin and provide the explanation for on-source keV X-ray
flares that ionize the neon microjet.
| arxiv topic:astro-ph.SR astro-ph.GA |
arxiv_dataset-78751611.02053 | Reinforcement-based Simultaneous Algorithm and its Hyperparameters
Selection
cs.LG cs.AI stat.ML
Many algorithms for data analysis exist, especially for classification
problems. To solve a data analysis problem, a proper algorithm should be
chosen, and also its hyperparameters should be selected. In this paper, we
present a new method for the simultaneous selection of an algorithm and its
hyperparameters. In order to do so, we reduced this problem to the multi-armed
bandit problem. We consider an algorithm as an arm and algorithm
hyperparameters search during a fixed time as the corresponding arm play. We
also suggest a problem-specific reward function. We performed the experiments
on 10 real datasets and compare the suggested method with the existing one
implemented in Auto-WEKA. The results show that our method is significantly
better in most of the cases and never worse than the Auto-WEKA.
| arxiv topic:cs.LG cs.AI stat.ML |
arxiv_dataset-78761611.02153 | Fabrication of polarization-independent waveguides deeply buried in
crystal using aberration-corrected femtosecond laser direct writing
physics.ins-det
Writing optical waveguides with femtosecond laser pulses provides the
capability of forming three-dimensional photonic circuits for manipulating
light fields in both linear and nonlinear manners. To fully explore this
potential, large depths of the buried waveguides in transparent substrates are
often desirable to facilitate achieving vertical integration of waveguides in a
multi-layer configuration, which, however, is hampered by rapidly degraded
axial resolution caused by optical aberration. Here, we show that with the
correction of the spherical aberration, polarization-independent waveguides can
be inscribed in a nonlinear optical crystal lithium niobate (LN) at depths up
to 1.4 mm, which is more than one order of magnitude deeper than the waveguides
written with aberration uncorrected femtosecond laser pulses. Our technique is
beneficial for applications ranging from miniaturized nonlinear light sources
to quantum information processing.
| arxiv topic:physics.ins-det |
arxiv_dataset-78771611.02253 | A relativistic compact stellar model of anisotropic quark matter mixed
with dark energy
gr-qc
The possibility of strange stars mixed with dark energy to be one of the
candidates for dark energy stars is the main issue of the present study. Our
investigation shows that quark matter acts as dark energy after a certain yet
unknown critical condition inside the quark stars. Our proposed model reveals
that strange stars mixed with dark energy feature a physically acceptable
stable model mimic characteristics of dark energy stars. The plausible
connections are shown through the mass-radius relation as well as the entropy
and temperature. We particularly note that a two-fluid distribution is a major
reason for the anisotropic nature of the spherical stellar system.
| arxiv topic:gr-qc |
arxiv_dataset-78781611.02353 | Enhanced Higgs associated production with a top quark pair in the NMSSM
with light singlets
hep-ph hep-ex
Precision measurements of the 125 GeV Higgs resonance recently discovered at
the LHC have determined that its properties are similar to the ones of the
Standard Model (SM) Higgs boson. However, the current uncertainties in the
determination of the Higgs boson couplings leave room for significant
deviations from the SM expectations. In fact, if one assumes no correlation
between the top-quark and gluon couplings to the Higgs, the current global fit
to the Higgs data lead to central values of the Higgs couplings to the
bottom-quark and the top-quark that are about 2 $\sigma$ away from the SM
predictions. In a previous work, we showed that such a scenario could be
realized in the Next to Minimal Supersymmetric extension of the SM (NMSSM), for
heavy singlets and light MSSM-like Higgs bosons and scalar top quarks, but for
couplings that ruined the perturbative consistency of the theory up to the GUT
scale. In this work we show that a perturbative consistent scenario, for
somewhat heavier stops, may be obtained in the presence of light singlets. An
interesting bonus of this scenario is the possibility of explaining an excess
of events observed in CP-even Higgs searches at LEP2.
| arxiv topic:hep-ph hep-ex |
arxiv_dataset-78791611.02453 | The Data Complexity of Description Logic Ontologies
cs.AI
We analyze the data complexity of ontology-mediated querying where the
ontologies are formulated in a description logic (DL) of the ALC family and
queries are conjunctive queries, positive existential queries, or acyclic
conjunctive queries. Our approach is non-uniform in the sense that we aim to
understand the complexity of each single ontology instead of for all ontologies
formulated in a certain language. While doing so, we quantify over the queries
and are interested, for example, in the question whether all queries can be
evaluated in polynomial time w.r.t. a given ontology. Our results include a
PTime/coNP-dichotomy for ontologies of depth one in the description logic
ALCFI, the same dichotomy for ALC- and ALCI-ontologies of unrestricted depth,
and the non-existence of such a dichotomy for ALCF-ontologies. For the latter
DL, we additionally show that it is undecidable whether a given ontology admits
PTime query evaluation. We also consider the connection between PTime query
evaluation and rewritability into (monadic) Datalog.
| arxiv topic:cs.AI |
arxiv_dataset-78801611.02553 | Weak {$q$}-concavity conditions for {$CR$}-manifolds
math.CV
We introduce various notions of q-pseudo-concavity for abstract CR manifolds
and we apply these notions to the study of hyoo-ellipticity, maximum modulus
principle and Cauchy problems for CR functions.
| arxiv topic:math.CV |
arxiv_dataset-78811611.02653 | Conditional Square Functions, the Sine-Cosine Decomposition for Hardy
Martingales and Dyadic Perturbation
math.FA
We prove that the $\cal P$ norm estimate between a Hardy martingale and its
cosine part are stable under dyadic perturbations, and show how dyadic
stability of the $\cal P$ norm estimate is used in the proof that $L^1$ embeds
into $L^1/H^1$.
| arxiv topic:math.FA |
arxiv_dataset-78821611.02753 | Peak-height formula for higher-order breathers of the nonlinear
Schr\"odinger equation on non-uniform backgrounds
nlin.PS
Given any background (or seed) solution of the nonlinear Schr\"odinger
equation, the Darboux transformation can be used to generate higher-order
breathers with much greater peak intensities. The Darboux transformation is
generic in iterating a pair of generating solutions of the Lax-pair equation
which preserves the solution of the nonlinear Schr\"odinger equation as a
consistency condition. The Darboux transformation itself knows nothing about
the background solution except through the initial pair of Lax solutions.
Because of this, in this work, we can prove in an unified manner, and without
knowing the analytical form of the background solution, that the peak-height of
a high-order breather, is just a sum of peak-heights of first-order breathers
plus that of the background, {\it irrespective} of the specific choice of the
background. Detailed results are verified for breathers on a cnoidal
background. Generalizations to more extended nonlinear Schr\"odinger equations
are also indicated.
| arxiv topic:nlin.PS |
arxiv_dataset-78831611.02853 | Towards a Stateful Forwarding Abstraction to Implement Scalable Network
Functions in Software and Hardware
cs.NI
An effective packet processing abstraction that leverages software or
hardware acceleration techniques can simplify the implementation of
high-performance virtual network functions. In this paper, we explore the
suitability of SDN switches' stateful forwarding abstractions to model
accelerated functions in both software and hardware accelerators, such as
optimized software switches and FPGA-based NICs. In particular, we select an
Extended Finite State Machine abstraction and demonstrate its suitability by
implementing the Linux's iptables interface. By doing so, we provide the
acceleration of functions such as stateful firewalls, load balancers and
dynamic NATs. We find that supporting a flow-level programming consistency
model is an important feature of a programming abstraction in this context.
Furthermore, we demonstrate that such a model simplifies the scaling of the
system when implemented in software, enabling efficient multi-core processing
without harming state consistency.
| arxiv topic:cs.NI |
arxiv_dataset-78841611.02953 | Consequences of the functional equation of the $p$-adic $L$-function of
an elliptic curve
math.NT
We prove that the first two coefficients in the series expansion around $s=1$
of the $p$-adic $L$-function of an elliptic curve over $\mathbb{Q}$ are related
by a formula involving the conductor of the curve. This is analogous to a
recent result of Wuthrich for the classical $L$-function, which makes use of
the functional equation. We present a few other consequences for the $p$-adic
$L$-function and a generalisation to the base-change to an abelian number
field.
| arxiv topic:math.NT |
arxiv_dataset-78851611.03053 | Applying Bag of System Calls for Anomalous Behavior Detection of
Applications in Linux Containers
cs.CR
In this paper, we present the results of using bags of system calls for
learning the behavior of Linux containers for use in anomaly-detection based
intrusion detection system. By using system calls of the containers monitored
from the host kernel for anomaly detection, the system does not require any
prior knowledge of the container nature, neither does it require altering the
container or the host kernel.
| arxiv topic:cs.CR |
arxiv_dataset-78861611.03153 | Dispersion relation and surface gravity of universal horizons
gr-qc
In Einstein-aether theory, violating Lorentz invariance permits some
super-luminal communications, and the universal horizon can trap excitations
traveling at arbitrarily high velocities. To better understand the nature of
these universal horizons, we first modify the ray tracing method, and then use
it to study their surface gravity in charged Einstein-aether black hole
spacetime. Instead of the previous result in Ref. [Phys. Rev. D 89, 064061],
our results show that the surface gravity of the universal horizon is dependent
on the specific dispersion relation, $\kappa_{UH}=2(z-1)\kappa_{uh}/z$, where
$z$ denotes the power of the leading term in the superluminal dispersion
relation, characterizing different species of particles. And the associated
Hawking temperatures also are different with $z$. These findings, which
coincide with those in Ref. [Nucl. Phys. B 913, 694] derived by the tunneling
method, provide some full understanding of black hole thermodynamics in
Lorentz-violating theories.
| arxiv topic:gr-qc |
arxiv_dataset-78871611.03253 | Constrained Submodular Maximization via a Non-symmetric Technique
cs.DS
The study of combinatorial optimization problems with a submodular objective
has attracted much attention in recent years. Such problems are important in
both theory and practice because their objective functions are very general.
Obtaining further improvements for many submodular maximization problems boils
down to finding better algorithms for optimizing a relaxation of them known as
the multilinear extension.
In this work we present an algorithm for optimizing the multilinear
relaxation whose guarantee improves over the guarantee of the best previous
algorithm (which was given by Ene and Nguyen (2016)). Moreover, our algorithm
is based on a new technique which is, arguably, simpler and more natural for
the problem at hand. In a nutshell, previous algorithms for this problem rely
on symmetry properties which are natural only in the absence of a constraint.
Our technique avoids the need to resort to such properties, and thus, seems to
be a better fit for constrained problems.
| arxiv topic:cs.DS |
arxiv_dataset-78881611.03353 | Optimization of Generalized Unary Coding
cs.DM
This paper proposes an optimum version of the recently advanced scheme for
generalized unary coding. In this method, the block of 1s that identifies the
number is allowed to be broken up, which extends the count. The result is
established by a theorem. The number count is now n(n-k-1)+1 rather than the
previously described (n-k)(n-k)-1.
| arxiv topic:cs.DM |
arxiv_dataset-78891611.03453 | On Service-Chaining Strategies using Virtual Network Functions in
Operator Networks
cs.NI
Network functions (e.g., firewalls, load balancers, etc.) have been
traditionally provided through proprietary hardware appliances. Often, hardware
appliances need to be hardwired back to back to form a service chain providing
chained network functions. Hardware appliances cannot be provisioned on demand
since they are statically embedded in the network topology, making creation,
insertion, modification, upgrade, and removal of service chains complex, and
also slowing down service innovation. Hence, network operators are starting to
deploy Virtual Network Functions (VNFs), which are virtualized over commodity
hardware. VNFs can be deployed in Data Centers (DCs) or in Network Function
Virtualization (NFV) capable network elements (nodes) such as routers and
switches. NFV capable nodes and DCs together form a Network enabled Cloud (NeC)
that helps to facilitate the dynamic service chaining required to support
evolving network traffic and its service demands. In this study, we focus on
the VNF service chain placement and traffic routing problem, and build a model
for placing a VNF service chain while minimizing network resource consumption.
Our results indicate that a NeC having a DC and NFV capable nodes can
significantly reduce network-resource consumption.
| arxiv topic:cs.NI |
arxiv_dataset-78901611.03553 | The Sum-Product Theorem: A Foundation for Learning Tractable Models
cs.LG cs.AI
Inference in expressive probabilistic models is generally intractable, which
makes them difficult to learn and limits their applicability. Sum-product
networks are a class of deep models where, surprisingly, inference remains
tractable even when an arbitrary number of hidden layers are present. In this
paper, we generalize this result to a much broader set of learning problems:
all those where inference consists of summing a function over a semiring. This
includes satisfiability, constraint satisfaction, optimization, integration,
and others. In any semiring, for summation to be tractable it suffices that the
factors of every product have disjoint scopes. This unifies and extends many
previous results in the literature. Enforcing this condition at learning time
thus ensures that the learned models are tractable. We illustrate the power and
generality of this approach by applying it to a new type of structured
prediction problem: learning a nonconvex function that can be globally
optimized in polynomial time. We show empirically that this greatly outperforms
the standard approach of learning without regard to the cost of optimization.
| arxiv topic:cs.LG cs.AI |
arxiv_dataset-78911611.03653 | Chiral Thermodynamics in a finite box
hep-ph hep-th nucl-th
Finite-volume modifications of the two-flavor chiral phase diagram are
investigated within an effective quark-meson model in various mean-field
approximations. The role of vacuum fluctuations and boundary conditions, their
influence on higher cumulants and signatures of a possible pseudo-critical
endpoint are amplified with smaller volumes.
| arxiv topic:hep-ph hep-th nucl-th |
arxiv_dataset-78921611.03753 | Properties of Star Clusters -- III: Analysis of 13 FSR Clusters using
UKIDSS-GPS and VISTA-VVV
astro-ph.GA
Discerning the nature of open cluster candidates is essential for both
individual and statistical analyses of cluster properties. Here we establish
the nature of thirteen cluster candidates from the FSR cluster list using
photometry from the 2MASS and deeper, higher resolution UKIDSS-GPS and
VISTA-VVV surveys. These clusters were selected because they were flagged in
our previous studies as expected to contain a large proportion of pre-main
sequence members or are at unusually small/large Galactocentric distances. We
employ a decontamination procedure of JHK photometry to identify cluster
members. Cluster properties are homogeneously determined and we conduct a cross
comparative study of our results with the literature (where available). Seven
of the here studied clusters were confirmed to contain PMS stars, one of which
is a newly confirmed cluster. Our study of FSR1716 is the deepest to date and
is in notable disagreement with previous studies, finding that it has a
distance of about 7.3kpc and age of 10-12Gyr. As such, we argue that this
cluster is a potential globular cluster candidate.
| arxiv topic:astro-ph.GA |
arxiv_dataset-78931611.03853 | Gravitational Waves, Gamma Ray Bursts, and Black Stars
gr-qc astro-ph.CO hep-th
Stars that are collapsing toward forming a black hole but appear frozen near
their Schwarzschild horizon are termed "black stars". The collision of two
black stars leads to gravitational radiation during the merging phase followed
by a delayed gamma ray burst during coalescence. The recent observation of
gravitational waves by LIGO, followed by a possible gamma ray counterpart by
Fermi, suggests that the source may have been a merger of two black stars with
profound implications for quantum gravity and the nature of black holes.
| arxiv topic:gr-qc astro-ph.CO hep-th |
arxiv_dataset-78941611.03953 | A birational embedding of an algebraic curve into a projective plane
with two Galois points
math.AG
A criterion for the existence of a birational embedding of an algebraic curve
into a projective plane with two Galois points is presented. Several novel
examples of plane curves with two inner Galois points as an application are
described.
| arxiv topic:math.AG |
arxiv_dataset-78951611.04053 | The Structure of the Test Function for Phenomenological Modelling of
Eclipsing Binaries
astro-ph.SR
The dependence of the test function on the phenomenological parameters used
in the "NAV" ("New Algol Variable") algorithm (Andronov, 2012Ap.....55..536A)
is studied. Due to a presence of local minima, the method of minimization
contains two steps: the "brute force" minimization at a grid in the 4D
parameter space, and further iterations using the differential corrections.
This method represents an effective approximation of the light curve using the
special pattern (shape) separately for the primary and secondary minima. The
application of the method to concrete stars is briefly reviewed.
| arxiv topic:astro-ph.SR |
arxiv_dataset-78961611.04153 | Higher order semi-implicit schemes for linear advection equation on
Cartesian grids with numerical stability analysis
math.NA
A new class of semi-implicit numerical schemes for linear advection equation
on Cartesian grids is derived that is inspired by so-called $\kappa$-schemes
used with fully explicit discretizations for this type of problems. Opposite to
fully explicit $\kappa$-scheme the semi-implicit variant is unconditionally
stable in one-dimensional case and it preserves second order accuracy for
dimension by dimension extension in higher dimensional cases. We discuss von
Neumann stability conditions numerically for all numerical schemes. Using
so-called Corner Transport Upwind extension of two-dimensional semi-implicit
scheme with a special choice of $\kappa$ parameters, a second order accurate
method is obtained for which numerical unconditional stability can be shown for
variable velocity and the third order accuracy can be proved for constant
velocity. Several numerical experiments illustrate the properties of
semi-implicit schemes for chosen examples.
| arxiv topic:math.NA |
arxiv_dataset-78971611.04253 | Open Charm decays and spectroscopy at Belle
hep-ex
In this review we report the recent results of open charm decays and
spectroscopy using the data collected with the Belle detector at the KEKB
asymmetric-energy e+e- collider.
| arxiv topic:hep-ex |
arxiv_dataset-78981611.04353 | Herding Generalizes Diverse M -Best Solutions
cs.CV
We show that the algorithm to extract diverse M -solutions from a Conditional
Random Field (called divMbest [1]) takes exactly the form of a Herding
procedure [2], i.e. a deterministic dynamical system that produces a sequence
of hypotheses that respect a set of observed moment constraints. This
generalization enables us to invoke properties of Herding that show that
divMbest enforces implausible constraints which may yield wrong assumptions for
some problem settings. Our experiments in semantic segmentation demonstrate
that seeing divMbest as an instance of Herding leads to better alternatives for
the implausible constraints of divMbest.
| arxiv topic:cs.CV |
arxiv_dataset-78991611.04453 | Finitely stable racks and rack representations
math.RT math.GR math.GT math.QA math.RA
We define a new class of racks, called finitely stable racks, which, to some
extent, share various flavors with Abelian groups. Characterization of finitely
stable Alexander quandles is established. Further, we study twisted rack
dynamical systems, construct their cross-products, and introduce representation
theory of racks and quandles. We prove several results on the {\em strong}
representations of finite connected involutive racks analogous to the
properties of finite Abelian groups. Finally, we define the {\em Pontryagin}
dual of a rack as an Abelian group which, in the finite involutive connected
case, coincides with the set of its strong irreducible representations.
| arxiv topic:math.RT math.GR math.GT math.QA math.RA |
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