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Title: Predicting Oral Disintegrating Tablet Formulations by Neural Network Techniques,
Abstract: Oral Disintegrating Tablets (ODTs) is a novel dosage form that can be
dissolved on the tongue within 3min or less especially for geriatric and
pediatric patients. Current ODT formulation studies usually rely on the
personal experience of pharmaceutical experts and trial-and-error in the
laboratory, which is inefficient and time-consuming. The aim of current
research was to establish the prediction model of ODT formulations with direct
compression process by Artificial Neural Network (ANN) and Deep Neural Network
(DNN) techniques. 145 formulation data were extracted from Web of Science. All
data sets were divided into three parts: training set (105 data), validation
set (20) and testing set (20). ANN and DNN were compared for the prediction of
the disintegrating time. The accuracy of the ANN model has reached 85.60%,
80.00% and 75.00% on the training set, validation set and testing set
respectively, whereas that of the DNN model was 85.60%, 85.00% and 80.00%,
respectively. Compared with the ANN, DNN showed the better prediction for ODT
formulations. It is the first time that deep neural network with the improved
dataset selection algorithm is applied to formulation prediction on small data.
The proposed predictive approach could evaluate the critical parameters about
quality control of formulation, and guide research and process development. The
implementation of this prediction model could effectively reduce drug product
development timeline and material usage, and proactively facilitate the
development of a robust drug product. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: First non-icosahedral boron allotrope synthesized at high pressure and high temperature,
Abstract: Theoretical predictions of pressure-induced phase transformations often
become long-standing enigmas because of limitations of contemporary available
experimental possibilities. Hitherto the existence of a non-icosahedral boron
allotrope has been one of them. Here we report on the first non-icosahedral
boron allotrope, which we denoted as {\zeta}-B, with the orthorhombic
{\alpha}-Ga-type structure (space group Cmce) synthesized in a diamond anvil
cell at extreme high-pressure high-temperature conditions (115 GPa and 2100 K).
The structure of {\zeta}-B was solved using single-crystal synchrotron X-ray
diffraction and its compressional behavior was studied in the range of very
high pressures (115 GPa to 135 GPa). Experimental validation of theoretical
predictions reveals the degree of our up-to-date comprehension of condensed
matter and promotes further development of the solid state physics and
chemistry. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Inconsistency of Template Estimation with the Fr{é}chet mean in Quotient Space,
Abstract: We tackle the problem of template estimation when data have been randomly
transformed under an isometric group action in the presence of noise. In order
to estimate the template, one often minimizes the variance when the influence
of the transformations have been removed (computation of the Fr{é}chet mean
in quotient space). The consistency bias is defined as the distance (possibly
zero) between the orbit of the template and the orbit of one element which
minimizes the variance. In this article we establish an asymptotic behavior of
the consistency bias with respect to the noise level. This behavior is linear
with respect to the noise level. As a result the inconsistency is unavoidable
as soon as the noise is large enough. In practice, the template estimation with
a finite sample is often done with an algorithm called max-max. We show the
convergence of this algorithm to an empirical Karcher mean. Finally, our
numerical experiments show that the bias observed in practice cannot be
attributed to the small sample size or to a convergence problem but is indeed
due to the previously studied inconsistency. | [
0,
0,
1,
1,
0,
0
] | [
"Mathematics",
"Statistics"
] |
Title: Holographic coherent states from random tensor networks,
Abstract: Random tensor networks provide useful models that incorporate various
important features of holographic duality. A tensor network is usually defined
for a fixed graph geometry specified by the connection of tensors. In this
paper, we generalize the random tensor network approach to allow quantum
superposition of different spatial geometries. We set up a framework in which
all possible bulk spatial geometries, characterized by weighted adjacent
matrices of all possible graphs, are mapped to the boundary Hilbert space and
form an overcomplete basis of the boundary. We name such an overcomplete basis
as holographic coherent states. A generic boundary state can be expanded on
this basis, which describes the state as a superposition of different spatial
geometries in the bulk. We discuss how to define distinct classical geometries
and small fluctuations around them. We show that small fluctuations around
classical geometries define "code subspaces" which are mapped to the boundary
Hilbert space isometrically with quantum error correction properties. In
addition, we also show that the overlap between different geometries is
suppressed exponentially as a function of the geometrical difference between
the two geometries. The geometrical difference is measured in an area law
fashion, which is a manifestation of the holographic nature of the states
considered. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: Robust Tracking and Behavioral Modeling of Movements of Biological Collectives from Ordinary Video Recordings,
Abstract: We propose a novel computational method to extract information about
interactions among individuals with different behavioral states in a biological
collective from ordinary video recordings. Assuming that individuals are acting
as finite state machines, our method first detects discrete behavioral states
of those individuals and then constructs a model of their state transitions,
taking into account the positions and states of other individuals in the
vicinity. We have tested the proposed method through applications to two
real-world biological collectives: termites in an experimental setting and
human pedestrians in a university campus. For each application, a robust
tracking system was developed in-house, utilizing interactive human
intervention (for termite tracking) or online agent-based simulation (for
pedestrian tracking). In both cases, significant interactions were detected
between nearby individuals with different states, demonstrating the
effectiveness of the proposed method. | [
1,
1,
0,
0,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Nonlinear elliptic equations on Carnot groups,
Abstract: This article concerns a class of elliptic equations on Carnot groups
depending on one real positive parameter and involving a subcritical
nonlinearity (for the critical case we refer to G. Molica Bisci and D.
Repovš, Yamabe-type equations on Carnot groups, Potential Anal. 46:2
(2017), 369-383; arXiv:1705.10100 [math.AP]). As a special case of our results
we prove the existence of at least one nontrivial solution for a subelliptic
equation defined on a smooth and bounded domain $D$ of the Heisenberg group
$\mathbb{H}^n=\mathbb{C}^n\times \mathbb{R}$. The main approach is based on
variational methods. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: A Tidy Data Model for Natural Language Processing using cleanNLP,
Abstract: The package cleanNLP provides a set of fast tools for converting a textual
corpus into a set of normalized tables. The underlying natural language
processing pipeline utilizes Stanford's CoreNLP library, exposing a number of
annotation tasks for text written in English, French, German, and Spanish.
Annotators include tokenization, part of speech tagging, named entity
recognition, entity linking, sentiment analysis, dependency parsing,
coreference resolution, and information extraction. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: Relaxation of the EM Algorithm via Quantum Annealing for Gaussian Mixture Models,
Abstract: We propose a modified expectation-maximization algorithm by introducing the
concept of quantum annealing, which we call the deterministic quantum annealing
expectation-maximization (DQAEM) algorithm. The expectation-maximization (EM)
algorithm is an established algorithm to compute maximum likelihood estimates
and applied to many practical applications. However, it is known that EM
heavily depends on initial values and its estimates are sometimes trapped by
local optima. To solve such a problem, quantum annealing (QA) was proposed as a
novel optimization approach motivated by quantum mechanics. By employing QA, we
then formulate DQAEM and present a theorem that supports its stability.
Finally, we demonstrate numerical simulations to confirm its efficiency. | [
0,
1,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics",
"Physics"
] |
Title: Influence of broken-pair excitations on the exact pair wavefunction,
Abstract: Doubly occupied configuration interaction (DOCI), the exact diagonalization
of the Hamiltonian in the paired (seniority zero) sector of the Hilbert space,
is a combinatorial cost wave function that can be very efficiently approximated
by pair coupled cluster doubles (pCCD) at mean-field computational cost. As
such, it is a very interesting candidate as a starting point for building the
full configuration interaction (FCI) ground state eigenfunction belonging to
all (not just paired) seniority sectors. The true seniority zero sector of FCI
(referred to here as FCI${}_0$) includes the effect of coupling between all
seniority sectors rather than just seniority zero, and is, in principle,
different from DOCI. We here study the accuracy with which DOCI approximates
FCI${}_0$. Using a set of small Hubbard lattices, where FCI is possible, we
show that DOCI $\sim$ FCI${}_0$ under weak correlation. However, in the strong
correlation regime, the nature of the FCI${}_0$ wavefunction can change
significantly, rendering DOCI and pCCD a less than ideal starting point for
approximating FCI. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: Spatially resolved, energy-filtered imaging of core level and valence band photoemission of highly p and n doped silicon patterns,
Abstract: An accurate description of spatial variations in the energy levels of
patterned semiconductor substrates on the micron and sub-micron scale as a
function of local doping is an important technological challenge for the
microelectronics industry. Spatially resolved surface analysis by photoelectron
spectromicroscopy can provide an invaluable contribution thanks to the
relatively non-destructive, quantitative analysis. We present results on highly
doped n and p type patterns on, respectively, p and n type silicon substrates.
Using synchrotron radiation and spherical aberration-corrected energy
filtering, we have obtained a spectroscopic image series at the Si 2p core
level and across the valence band. Local band alignments are extracted,
accounting for doping, band bending and surface photovoltage. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Towards more Reliable Transfer Learning,
Abstract: Multi-source transfer learning has been proven effective when within-target
labeled data is scarce. Previous work focuses primarily on exploiting domain
similarities and assumes that source domains are richly or at least comparably
labeled. While this strong assumption is never true in practice, this paper
relaxes it and addresses challenges related to sources with diverse labeling
volume and diverse reliability. The first challenge is combining domain
similarity and source reliability by proposing a new transfer learning method
that utilizes both source-target similarities and inter-source relationships.
The second challenge involves pool-based active learning where the oracle is
only available in source domains, resulting in an integrated active transfer
learning framework that incorporates distribution matching and uncertainty
sampling. Extensive experiments on synthetic and two real-world datasets
clearly demonstrate the superiority of our proposed methods over several
baselines including state-of-the-art transfer learning methods. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Syzygies of Cohen-Macaulay modules over one dimensional Cohen-Macaulay local rings,
Abstract: We study syzygies of (maximal) Cohen-Macaulay modules over one dimensional
Cohen-Macaulay local rings. We compare these modules to Cohen-Macaulay modules
over the endomorphism ring of the maximal ideal. After this comparison, we give
several characterizations of almost Gorenstein rings in terms of syzygies of
Cohen-Macaulay modules. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: A functional perspective on emergent supersymmetry,
Abstract: We investigate the emergence of ${\cal N}=1$ supersymmetry in the long-range
behavior of three-dimensional parity-symmetric Yukawa systems. We discuss a
renormalization approach that manifestly preserves supersymmetry whenever such
symmetry is realized, and use it to prove that supersymmetry-breaking operators
are irrelevant, thus proving that such operators are suppressed in the
infrared. All our findings are illustrated with the aid of the
$\epsilon$-expansion and a functional variant of perturbation theory, but we
provide numerical estimates of critical exponents that are based on the
non-perturbative functional renormalization group. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: On the commutativity of the powerspace constructions,
Abstract: We investigate powerspace constructions on topological spaces, with a
particular focus on the category of quasi-Polish spaces. We show that the upper
and lower powerspaces commute on all quasi-Polish spaces, and show more
generally that this commutativity is equivalent to the topological property of
consonance. We then investigate powerspace constructions on the open set
lattices of quasi-Polish spaces, and provide a complete characterization of how
the upper and lower powerspaces distribute over the open set lattice
construction. | [
1,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Concentration of Multilinear Functions of the Ising Model with Applications to Network Data,
Abstract: We prove near-tight concentration of measure for polynomial functions of the
Ising model under high temperature. For any degree $d$, we show that a
degree-$d$ polynomial of a $n$-spin Ising model exhibits exponential tails that
scale as $\exp(-r^{2/d})$ at radius $r=\tilde{\Omega}_d(n^{d/2})$. Our
concentration radius is optimal up to logarithmic factors for constant $d$,
improving known results by polynomial factors in the number of spins. We
demonstrate the efficacy of polynomial functions as statistics for testing the
strength of interactions in social networks in both synthetic and real world
data. | [
1,
0,
1,
1,
0,
0
] | [
"Mathematics",
"Statistics",
"Quantitative Biology"
] |
Title: Width-tuned magnetic order oscillation on zigzag edges of honeycomb nanoribbons,
Abstract: Quantum confinement and interference often generate exotic properties in
nanostructures. One recent highlight is the experimental indication of a
magnetic phase transition in zigzag-edged graphene nanoribbons at the critical
ribbon width of about 7 nm [G. Z. Magda et al., Nature \textbf{514}, 608
(2014)]. Here we show theoretically that with further increase in the ribbon
width, the magnetic correlation of the two edges can exhibit an intriguing
oscillatory behavior between antiferromagnetic and ferromagnetic, driven by
acquiring the positive coherence between the two edges to lower the free
energy. The oscillation effect is readily tunable in applied magnetic fields.
These novel properties suggest new experimental manifestation of the edge
magnetic orders in graphene nanoribbons, and enhance the hopes of graphene-like
spintronic nanodevices functioning at room temperature. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Fast and accurate approximation of the full conditional for gamma shape parameters,
Abstract: The gamma distribution arises frequently in Bayesian models, but there is not
an easy-to-use conjugate prior for the shape parameter of a gamma. This
inconvenience is usually dealt with by using either Metropolis-Hastings moves,
rejection sampling methods, or numerical integration. However, in models with a
large number of shape parameters, these existing methods are slower or more
complicated than one would like, making them burdensome in practice. It turns
out that the full conditional distribution of the gamma shape parameter is well
approximated by a gamma distribution, even for small sample sizes, when the
prior on the shape parameter is also a gamma distribution. This article
introduces a quick and easy algorithm for finding a gamma distribution that
approximates the full conditional distribution of the shape parameter. We
empirically demonstrate the speed and accuracy of the approximation across a
wide range of conditions. If exactness is required, the approximation can be
used as a proposal distribution for Metropolis-Hastings. | [
0,
0,
0,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: Multi-Stakeholder Recommendation: Applications and Challenges,
Abstract: Recommender systems have been successfully applied to assist decision making
by producing a list of item recommendations tailored to user preferences.
Traditional recommender systems only focus on optimizing the utility of the end
users who are the receiver of the recommendations. By contrast,
multi-stakeholder recommendation attempts to generate recommendations that
satisfy the needs of both the end users and other parties or stakeholders. This
paper provides an overview and discussion about the multi-stakeholder
recommendations from the perspective of practical applications, available data
sets, corresponding research challenges and potential solutions. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Saturated absorption competition microscopy,
Abstract: We introduce the concept of saturated absorption competition (SAC) microscopy
as a means of providing sub-diffraction spatial resolution in fluorescence
imaging. Unlike the post-competition process between stimulated and spontaneous
emission that is used in stimulated emission depletion (STED) microscopy, SAC
microscopy breaks the diffraction limit by emphasizing a pre-competition
process that occurs in the fluorescence absorption stage in a manner that
shares similarities with ground-state depletion (GSD) microscopy. Moreover,
unlike both STED and GSD microscopy, SAC microscopy offers a reduction in
complexity and cost by utilizing only a single continuous-wave laser diode and
an illumination intensity that is ~ 20x smaller than that used in STED. Our
approach can be physically implemented in a confocal microscope by dividing the
input laser source into a time-modulated primary excitation beam and a
doughnut-shaped saturation beam, and subsequently employing a homodyne
detection scheme to select the modulated fluorescence signal. Herein, we
provide both a physico-chemical model of SAC and experimentally demonstrate by
way of a proof-of-concept experiment a transverse spatial resolution of
~lambda/6. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Quantitative Biology"
] |
Title: Phylogenetic networks that are their own fold-ups,
Abstract: Phylogenetic networks are becoming of increasing interest to evolutionary
biologists due to their ability to capture complex non-treelike evolutionary
processes. From a combinatorial point of view, such networks are certain types
of rooted directed acyclic graphs whose leaves are labelled by, for example,
species. A number of mathematically interesting classes of phylogenetic
networks are known. These include the biologically relevant class of stable
phylogenetic networks whose members are defined via certain fold-up and un-fold
operations that link them with concepts arising within the theory of, for
example, graph fibrations. Despite this exciting link, the structural
complexity of stable phylogenetic networks is still relatively poorly
understood. Employing the popular tree-based, reticulation-visible, and
tree-child properties which allow one to gauge this complexity in one way or
another, we provide novel characterizations for when a stable phylogenetic
network satisfies either one of these three properties. | [
0,
0,
0,
0,
1,
0
] | [
"Quantitative Biology",
"Mathematics"
] |
Title: Theoretically Principled Trade-off between Robustness and Accuracy,
Abstract: We identify a trade-off between robustness and accuracy that serves as a
guiding principle in the design of defenses against adversarial examples.
Although the problem has been widely studied empirically, much remains unknown
concerning the theory underlying this trade-off. In this work, we quantify the
trade-off in terms of the gap between the risk for adversarial examples and the
risk for non-adversarial examples. The challenge is to provide tight bounds on
this quantity in terms of a surrogate loss. We give an optimal upper bound on
this quantity in terms of classification-calibrated loss, which matches the
lower bound in the worst case. Inspired by our theoretical analysis, we also
design a new defense method, TRADES, to trade adversarial robustness off
against accuracy. Our proposed algorithm performs well experimentally in
real-world datasets. The methodology is the foundation of our entry to the
NeurIPS 2018 Adversarial Vision Challenge in which we won the 1st place out of
1,995 submissions in the robust model track, surpassing the runner-up approach
by $11.41\%$ in terms of mean $\ell_2$ perturbation distance. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics",
"Mathematics"
] |
Title: A Case for an Atmosphere on Super-Earth 55 Cancri e,
Abstract: One of the primary questions when characterizing Earth-sized and
super-Earth-sized exoplanets is whether they have a substantial atmosphere like
Earth and Venus or a bare-rock surface like Mercury. Phase curves of the
planets in thermal emission provide clues to this question, because a
substantial atmosphere would transport heat more efficiently than a bare-rock
surface. Analyzing phase curve photometric data around secondary eclipse has
previously been used to study energy transport in the atmospheres of hot
Jupiters. Here we use phase curve, Spitzer time-series photometry to study the
thermal emission properties of the super-Earth exoplanet 55 Cancri e. We
utilize a semi-analytical framework to fit a physical model to the infrared
photometric data at 4.5 micron. The model uses parameters of planetary
properties including Bond albedo, heat redistribution efficiency (i.e., ratio
between radiative timescale and advective timescale of the atmosphere), and
atmospheric greenhouse factor. The phase curve of 55 Cancri e is dominated by
thermal emission with an eastward-shifted hot spot. We determine the heat
redistribution efficiency to be ~1.47, which implies that the advective
timescale is on the same order as the radiative timescale. This requirement
cannot be met by the bare-rock planet scenario because heat transport by
currents of molten lava would be too slow. The phase curve thus favors the
scenario with a substantial atmosphere. Our constraints on the heat
redistribution efficiency translate to an atmospheric pressure of ~1.4 bar. The
Spitzer 4.5-micron band is thus a window into the deep atmosphere of the planet
55 Cancri e. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: From LiDAR to Underground Maps via 5G - Business Models Enabling a System-of-Systems Approach to Mapping the Kankberg Mine,
Abstract: With ever-increasing productivity targets in mining operations, there is a
growing interest in mining automation. The PIMM project addresses the
fundamental challenge of network communication by constructing a pilot 5G
network in the underground mine Kankberg. In this report, we discuss how such a
5G network could constitute the essential infrastructure to organize existing
systems in Kankberg into a system-of-systems (SoS). In this report, we analyze
a scenario in which LiDAR equipped vehicles operating in the mine are connected
to existing mine mapping and positioning solutions. The approach is motivated
by the approaching era of remote controlled, or even autonomous, vehicles in
mining operations. The proposed SoS could ensure continuously updated maps of
Kankberg, rendered in unprecedented detail, supporting both productivity and
safety in the underground mine. We present four different SoS solutions from an
organizational point of view, discussing how development and operations of the
constituent systems could be distributed among Boliden and external
stakeholders, e.g., the vehicle suppliers, the hauling company, and the
developers of the mapping software. The four scenarios are compared from both
technical and business perspectives, and based on trade-off discussions and
SWOT analyses. We conclude our report by recommending continued research along
two future paths, namely a closer cooperation with the vehicle suppliers, and
further feasibility studies regarding establishing a Kankberg software
ecosystem. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Quantitative Finance"
] |
Title: The number of realizations of a Laman graph,
Abstract: Laman graphs model planar frameworks that are rigid for a general choice of
distances between the vertices. There are finitely many ways, up to isometries,
to realize a Laman graph in the plane. Such realizations can be seen as
solutions of systems of quadratic equations prescribing the distances between
pairs of points. Using ideas from algebraic and tropical geometry, we provide a
recursive formula for the number of complex solutions of such systems. | [
1,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: De Rham and twisted cohomology of Oeljeklaus-Toma manifolds,
Abstract: Oeljeklaus-Toma (OT) manifolds are complex non-Kähler manifolds whose
construction arises from specific number fields. In this note, we compute their
de Rham cohomology in terms of invariants associated to the background number
field. This is done by two distinct approaches, one using invariant cohomology
and the other one using the Leray-Serre spectral sequence. In addition, we
compute also their Morse-Novikov cohomology. As an application, we show that
the low degree Chern classes of any complex vector bundle on an OT manifold
vanish in the real cohomology. Other applications concern the OT manifolds
admitting locally conformally Kähler (LCK) metrics: we show that there is
only one possible Lee class of an LCK metric, and we determine all the possible
Morse-Novikov classes of an LCK metric, which implies the nondegeneracy of
certain Lefschetz maps in cohomology. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Origin of X-ray and gamma-ray emission from the Galactic central region,
Abstract: We study a possible connection between different non-thermal emissions from
the inner few parsecs of the Galaxy. We analyze the origin of the gamma-ray
source 2FGL J1745.6-2858 (or 3FGL J1745.6-2859c) in the Galactic Center and the
diffuse hard X-ray component recently found by NuSTAR, as well as the radio
emission and processes of hydrogen ionization from this area. We assume that a
source in the GC injected energetic particles with power-law spectrum into the
surrounding medium in the past or continues to inject until now. The energetic
particles may be protons, electrons or a combination of both. These particles
diffuse to the surrounding medium and interact with gas, magnetic field and
background photons to produce non-thermal emissions. We study the spectral and
spatial features of the hard X-ray emission and gamma-ray emission by the
particles from the central source. Our goal is to examine whether the hard
X-ray and gamma-ray emissions have a common origin. Our estimations show that
in the case of pure hadronic models the expected flux of hard X-ray emission is
too low. Despite protons can produce a non-zero contribution in gamma-ray
emission, it is unlikely that they and their secondary electrons can make a
significant contribution in hard X-ray flux. In the case of pure leptonic
models it is possible to reproduce both X-ray and gamma-ray emissions for both
transient and continuous supply models. However, in the case of continuous
supply model the ionization rate of molecular hydrogen may significantly exceed
the observed value. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Multiple Improvements of Multiple Imputation Likelihood Ratio Tests,
Abstract: Multiple imputation (MI) inference handles missing data by first properly
imputing the missing values $m$ times, and then combining the $m$ analysis
results from applying a complete-data procedure to each of the completed
datasets. However, the existing method for combining likelihood ratio tests has
multiple defects: (i) the combined test statistic can be negative in practice
when the reference null distribution is a standard $F$ distribution; (ii) it is
not invariant to re-parametrization; (iii) it fails to ensure monotonic power
due to its use of an inconsistent estimator of the fraction of missing
information (FMI) under the alternative hypothesis; and (iv) it requires
non-trivial access to the likelihood ratio test statistic as a function of
estimated parameters instead of datasets. This paper shows, via both
theoretical derivations and empirical investigations, that essentially all of
these problems can be straightforwardly addressed if we are willing to perform
an additional likelihood ratio test by stacking the $m$ completed datasets as
one big completed dataset. A particularly intriguing finding is that the FMI
itself can be estimated consistently by a likelihood ratio statistic for
testing whether the $m$ completed datasets produced by MI can be regarded
effectively as samples coming from a common model. Practical guidelines are
provided based on an extensive comparison of existing MI tests. | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: Estimating the unseen from multiple populations,
Abstract: Given samples from a distribution, how many new elements should we expect to
find if we continue sampling this distribution? This is an important and
actively studied problem, with many applications ranging from unseen species
estimation to genomics. We generalize this extrapolation and related unseen
estimation problems to the multiple population setting, where population $j$
has an unknown distribution $D_j$ from which we observe $n_j$ samples. We
derive an optimal estimator for the total number of elements we expect to find
among new samples across the populations. Surprisingly, we prove that our
estimator's accuracy is independent of the number of populations. We also
develop an efficient optimization algorithm to solve the more general problem
of estimating multi-population frequency distributions. We validate our methods
and theory through extensive experiments. Finally, on a real dataset of human
genomes across multiple ancestries, we demonstrate how our approach for unseen
estimation can enable cohort designs that can discover interesting mutations
with greater efficiency. | [
1,
0,
0,
1,
0,
0
] | [
"Statistics",
"Mathematics",
"Quantitative Biology"
] |
Title: Spatially Transformed Adversarial Examples,
Abstract: Recent studies show that widely used deep neural networks (DNNs) are
vulnerable to carefully crafted adversarial examples. Many advanced algorithms
have been proposed to generate adversarial examples by leveraging the
$\mathcal{L}_p$ distance for penalizing perturbations. Researchers have
explored different defense methods to defend against such adversarial attacks.
While the effectiveness of $\mathcal{L}_p$ distance as a metric of perceptual
quality remains an active research area, in this paper we will instead focus on
a different type of perturbation, namely spatial transformation, as opposed to
manipulating the pixel values directly as in prior works. Perturbations
generated through spatial transformation could result in large $\mathcal{L}_p$
distance measures, but our extensive experiments show that such spatially
transformed adversarial examples are perceptually realistic and more difficult
to defend against with existing defense systems. This potentially provides a
new direction in adversarial example generation and the design of corresponding
defenses. We visualize the spatial transformation based perturbation for
different examples and show that our technique can produce realistic
adversarial examples with smooth image deformation. Finally, we visualize the
attention of deep networks with different types of adversarial examples to
better understand how these examples are interpreted. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science"
] |
Title: Arrow Categories of Monoidal Model Categories,
Abstract: We prove that the arrow category of a monoidal model category, equipped with
the pushout product monoidal structure and the projective model structure, is a
monoidal model category. This answers a question posed by Mark Hovey, and has
the important consequence that it allows for the consideration of a monoidal
product in cubical homotopy theory. As illustrations we include numerous
examples of non-cofibrantly generated monoidal model categories, including
chain complexes, small categories, topological spaces, and pro-categories. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: HoloScope: Topology-and-Spike Aware Fraud Detection,
Abstract: As online fraudsters invest more resources, including purchasing large pools
of fake user accounts and dedicated IPs, fraudulent attacks become less obvious
and their detection becomes increasingly challenging. Existing approaches such
as average degree maximization suffer from the bias of including more nodes
than necessary, resulting in lower accuracy and increased need for manual
verification. Hence, we propose HoloScope, which uses information from graph
topology and temporal spikes to more accurately detect groups of fraudulent
users. In terms of graph topology, we introduce "contrast suspiciousness," a
dynamic weighting approach, which allows us to more accurately detect
fraudulent blocks, particularly low-density blocks. In terms of temporal
spikes, HoloScope takes into account the sudden bursts and drops of fraudsters'
attacking patterns. In addition, we provide theoretical bounds for how much
this increases the time cost needed for fraudsters to conduct adversarial
attacks. Additionally, from the perspective of ratings, HoloScope incorporates
the deviation of rating scores in order to catch fraudsters more accurately.
Moreover, HoloScope has a concise framework and sub-quadratic time complexity,
making the algorithm reproducible and scalable. Extensive experiments showed
that HoloScope achieved significant accuracy improvements on synthetic and real
data, compared with state-of-the-art fraud detection methods. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Convexity of level lines of Martin functions and applications,
Abstract: Let $\Omega$ be an unbounded domain in $\mathbb{R}\times\mathbb{R}^{d}.$ A
positive harmonic function $u$ on $\Omega$ that vanishes on the boundary of
$\Omega$ is called a Martin function. In this note, we show that, when $\Omega$
is convex, the superlevel sets of a Martin function are also convex. As a
consequence we obtain that if in addition $\Omega$ is symmetric, then the
maximum of any Martin function along a slice $\Omega\cap
(\{t\}\times\mathbb{R}^d)$ is attained at $(t,0).$ | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Spin Transport and Accumulation in 2D Weyl Fermion System,
Abstract: In this work, we study the spin Hall effect and Rashba-Edelstein effect of a
2D Weyl fermion system in the clean limit using the Kubo formalism. Spin
transport is solely due to the spin-torque current in this strongly spin-orbit
coupled (SOC) system, and chiral spin-flip scattering off non-SOC scalar
impurities, with potential strength $V$ and size $a$, gives rise to a
skew-scattering mechanism for the spin Hall effect. The key result is that the
resultant spin-Hall angle has a fixed sign, with $\theta^{SH} \sim O
\left(\tfrac{V^2}{v_F^2/a^2} (k_F a)^4 \right)$ being a strongly-dependent
function of $k_F a$, with $k_F$ and $v_F$ being the Fermi wave-vector and Fermi
velocity respectively. This, therefore, allows for the possibility of tuning
the SHE by adjusting the Fermi energy or impurity size. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Perfect Edge Domination: Hard and Solvable Cases,
Abstract: Let $G$ be an undirected graph. An edge of $G$ dominates itself and all edges
adjacent to it. A subset $E'$ of edges of $G$ is an edge dominating set of $G$,
if every edge of the graph is dominated by some edge of $E'$. We say that $E'$
is a perfect edge dominating set of $G$, if every edge not in $E'$ is dominated
by exactly one edge of $E'$. The perfect edge dominating problem is to
determine a least cardinality perfect edge dominating set of $G$. For this
problem, we describe two NP-completeness proofs, for the classes of claw-free
graphs of degree at most 3, and for bounded degree graphs, of maximum degree at
most $d \geq 3$ and large girth. In contrast, we prove that the problem admits
an $O(n)$ time solution, for cubic claw-free graphs. In addition, we prove a
complexity dichotomy theorem for the perfect edge domination problem, based on
the results described in the paper. Finally, we describe a linear time
algorithm for finding a minimum weight perfect edge dominating set of a
$P_5$-free graph. The algorithm is robust, in the sense that, given an
arbitrary graph $G$, either it computes a minimum weight perfect edge
dominating set of $G$, or it exhibits an induced subgraph of $G$, isomorphic to
a $P_5$. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: On codimension two flats in Fermat-type arrangements,
Abstract: In the present note we study certain arrangements of codimension $2$ flats in
projective spaces, we call them "Fermat arrangements". We describe algebraic
properties of their defining ideals. In particular, we show that they provide
counterexamples to an expected containment relation between ordinary and
symbolic powers of homogeneous ideals. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Invariant Causal Prediction for Sequential Data,
Abstract: We investigate the problem of inferring the causal predictors of a response
$Y$ from a set of $d$ explanatory variables $(X^1,\dots,X^d)$. Classical
ordinary least squares regression includes all predictors that reduce the
variance of $Y$. Using only the causal predictors instead leads to models that
have the advantage of remaining invariant under interventions, loosely speaking
they lead to invariance across different "environments" or "heterogeneity
patterns". More precisely, the conditional distribution of $Y$ given its causal
predictors remains invariant for all observations. Recent work exploits such a
stability to infer causal relations from data with different but known
environments. We show that even without having knowledge of the environments or
heterogeneity pattern, inferring causal relations is possible for time-ordered
(or any other type of sequentially ordered) data. In particular, this allows
detecting instantaneous causal relations in multivariate linear time series
which is usually not the case for Granger causality. Besides novel methodology,
we provide statistical confidence bounds and asymptotic detection results for
inferring causal predictors, and present an application to monetary policy in
macroeconomics. | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Computer Science",
"Quantitative Finance"
] |
Title: Ab initio calculations of the concentration dependent band gap reduction in dilute nitrides,
Abstract: While being of persistent interest for the integration of lattice-matched
laser devices with silicon circuits, the electronic structure of dilute nitride
III/V-semiconductors has presented a challenge to ab initio computational
approaches. The root of this lies in the strong distortion N atoms exert on
most host materials. Here, we resolve these issues by combining density
functional theory calculations based on the meta-GGA functional presented by
Tran and Blaha (TB09) with a supercell approach for the dilute nitride Ga(NAs).
Exploring the requirements posed to supercells, we show that the distortion
field of a single N atom must be allowed to decrease so far, that it does not
overlap with its periodic images. This also prevents spurious electronic
interactions between translational symmetric atoms, allowing to compute band
gaps in very good agreement with experimentally derived reference values. These
results open up the field of dilute nitride compound semiconductors to
predictive ab initio calculations. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Dynamic Safe Interruptibility for Decentralized Multi-Agent Reinforcement Learning,
Abstract: In reinforcement learning, agents learn by performing actions and observing
their outcomes. Sometimes, it is desirable for a human operator to
\textit{interrupt} an agent in order to prevent dangerous situations from
happening. Yet, as part of their learning process, agents may link these
interruptions, that impact their reward, to specific states and deliberately
avoid them. The situation is particularly challenging in a multi-agent context
because agents might not only learn from their own past interruptions, but also
from those of other agents. Orseau and Armstrong defined \emph{safe
interruptibility} for one learner, but their work does not naturally extend to
multi-agent systems. This paper introduces \textit{dynamic safe
interruptibility}, an alternative definition more suited to decentralized
learning problems, and studies this notion in two learning frameworks:
\textit{joint action learners} and \textit{independent learners}. We give
realistic sufficient conditions on the learning algorithm to enable dynamic
safe interruptibility in the case of joint action learners, yet show that these
conditions are not sufficient for independent learners. We show however that if
agents can detect interruptions, it is possible to prune the observations to
ensure dynamic safe interruptibility even for independent learners. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Only in the standard representation the Dirac theory is a quantum theory of a single fermion,
Abstract: It is shown that the relativistic quantum mechanics of a single fermion can
be developed only on the basis of the standard representation of the Dirac
bispinor. As in the nonrelativistic quantum mechanics, the arbitrariness in
defining the bispinor, as a four-component wave function, is restricted by its
multiplication by an arbitrary phase factor. We reveal the role of the large
and small components of the bispinor, establish their link in the
nonrelativistic limit with the Pauli spinor, as well as explain the role of
states with negative energies. The Klein tunneling is treated here as a
physical phenomenon analogous to the propagation of the electromagnetic wave in
a medium with negative dielectric permittivity and permeability. For the case
of localized stationary states we define the effective one-particle operators
which act in the space of the large component but contain the contributions of
both components. The effective operator of energy is presented in a compact
analytical form. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: An influence-based fast preceding questionnaire model for elderly assessments,
Abstract: To improve the efficiency of elderly assessments, an influence-based fast
preceding questionnaire model (FPQM) is proposed. Compared with traditional
assessments, the FPQM optimizes questionnaires by reordering their attributes.
The values of low-ranking attributes can be predicted by the values of the
high-ranking attributes. Therefore, the number of attributes can be reduced
without redesigning the questionnaires. A new function for calculating the
influence of the attributes is proposed based on probability theory. Reordering
and reducing algorithms are given based on the attributes' influences. The
model is verified through a practical application. The practice in an
elderly-care company shows that the FPQM can reduce the number of attributes by
90.56% with a prediction accuracy of 98.39%. Compared with other methods, such
as the Expert Knowledge, Rough Set and C4.5 methods, the FPQM achieves the best
performance. In addition, the FPQM can also be applied to other questionnaires. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: The Auger Engineering Radio Array and multi-hybrid cosmic ray detection (TAUP 2015),
Abstract: The Auger Engineering Radio Array (AERA) aims at the detection of air showers
induced by high-energy cosmic rays. As an extension of the Pierre Auger
Observatory, it measures complementary information to the particle detectors,
fluorescence telescopes and to the muon scintillators of the Auger Muons and
Infill for the Ground Array (AMIGA). AERA is sensitive to all fundamental
parameters of an extensive air shower such as the arrival direction, energy and
depth of shower maximum. Since the radio emission is induced purely by the
electromagnetic component of the shower, in combination with the AMIGA muon
counters, AERA is perfect for separate measurements of the electrons and muons
in the shower, if combined with a muon counting detector like AMIGA. In
addition to the depth of the shower maximum, the ratio of the electron and muon
number serves as a measure of the primary particle mass. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Factorization of arithmetic automorphic periods,
Abstract: In this paper, we prove that the arithmetic automorphic periods for $GL_{n}$
over a CM field factorize through the infinite places. This generalizes a
conjecture of Shimura in 1983, and is predicted by the Langlands correspondence
between automorphic representations and motives. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Locally Private Bayesian Inference for Count Models,
Abstract: As more aspects of social interaction are digitally recorded, there is a
growing need to develop privacy-preserving data analysis methods. Social
scientists will be more likely to adopt these methods if doing so entails
minimal change to their current methodology. Toward that end, we present a
general and modular method for privatizing Bayesian inference for Poisson
factorization, a broad class of models that contains some of the most widely
used models in the social sciences. Our method satisfies local differential
privacy, which ensures that no single centralized server need ever store the
non-privatized data. To formulate our local-privacy guarantees, we introduce
and focus on limited-precision local privacy---the local privacy analog of
limited-precision differential privacy (Flood et al., 2013). We present two
case studies, one involving social networks and one involving text corpora,
that test our method's ability to form the posterior distribution over latent
variables under different levels of noise, and demonstrate our method's utility
over a naïve approach, wherein inference proceeds as usual, treating the
privatized data as if it were not privatized. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Gender Differences in Participation and Reward on Stack Overflow,
Abstract: Programming is a valuable skill in the labor market, making the
underrepresentation of women in computing an increasingly important issue.
Online question and answer platforms serve a dual purpose in this field: they
form a body of knowledge useful as a reference and learning tool, and they
provide opportunities for individuals to demonstrate credible, verifiable
expertise. Issues, such as male-oriented site design or overrepresentation of
men among the site's elite may therefore compound the issue of women's
underrepresentation in IT. In this paper we audit the differences in behavior
and outcomes between men and women on Stack Overflow, the most popular of these
Q&A sites. We observe significant differences in how men and women participate
in the platform and how successful they are. For example, the average woman has
roughly half of the reputation points, the primary measure of success on the
site, of the average man. Using an Oaxaca-Blinder decomposition, an econometric
technique commonly applied to analyze differences in wages between groups, we
find that most of the gap in success between men and women can be explained by
differences in their activity on the site and differences in how these
activities are rewarded. Specifically, 1) men give more answers than women and
2) are rewarded more for their answers on average, even when controlling for
possible confounders such as tenure or buy-in to the site. Women ask more
questions and gain more reward per question. We conclude with a hypothetical
redesign of the site's scoring system based on these behavioral differences,
cutting the reputation gap in half. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Dynamic dipole polarizabilities of heteronuclear alkali dimers: optical response, trapping and control of ultracold molecules,
Abstract: In this article we address the general approach for calculating dynamical
dipole polarizabilities of small quantum systems, based on a sum-over-states
formula involving in principle the entire energy spectrum of the system. We
complement this method by a few-parameter model involving a limited number of
effective transitions, allowing for a compact and accurate representation of
both the isotropic and anisotropic components of the polarizability. We apply
the method to the series of ten heteronuclear molecules composed of two of
($^7$Li,$^{23}$Na,$^{39}$K,$^{87}$Rb,$^{133}$Cs) alkali-metal atoms. We rely on
both up-to-date spectroscopically-determined potential energy curves for the
lowest electronic states, and on our systematic studies of these systems
performed during the last decade for higher excited states and for permanent
and transition dipole moments. Such a compilation is timely for the
continuously growing researches on ultracold polar molecules. Indeed the
knowledge of the dynamic dipole polarizabilities is crucial to model the
optical response of molecules when trapped in optical lattices, and to
determine optimal lattice frequencies ensuring optimal transfer to the absolute
ground state of initially weakly-bound molecules. When they exist, we determine
the so-called "magic frequencies" where the ac-Stark shift and thus the viewed
trap depth, is the same for both weakly-bound and ground-state molecules. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: COPA: Constrained PARAFAC2 for Sparse & Large Datasets,
Abstract: PARAFAC2 has demonstrated success in modeling irregular tensors, where the
tensor dimensions vary across one of the modes. An example scenario is modeling
treatments across a set of patients with the varying number of medical
encounters over time. Despite recent improvements on unconstrained PARAFAC2,
its model factors are usually dense and sensitive to noise which limits their
interpretability. As a result, the following open challenges remain: a) various
modeling constraints, such as temporal smoothness, sparsity and non-negativity,
are needed to be imposed for interpretable temporal modeling and b) a scalable
approach is required to support those constraints efficiently for large
datasets. To tackle these challenges, we propose a {\it CO}nstrained {\it
PA}RAFAC2 (COPA) method, which carefully incorporates optimization constraints
such as temporal smoothness, sparsity, and non-negativity in the resulting
factors. To efficiently support all those constraints, COPA adopts a hybrid
optimization framework using alternating optimization and alternating direction
method of multiplier (AO-ADMM). As evaluated on large electronic health record
(EHR) datasets with hundreds of thousands of patients, COPA achieves
significant speedups (up to 36 times faster) over prior PARAFAC2 approaches
that only attempt to handle a subset of the constraints that COPA enables.
Overall, our method outperforms all the baselines attempting to handle a subset
of the constraints in terms of speed, while achieving the same level of
accuracy. Through a case study on temporal phenotyping of medically complex
children, we demonstrate how the constraints imposed by COPA reveal concise
phenotypes and meaningful temporal profiles of patients. The clinical
interpretation of both the phenotypes and the temporal profiles was confirmed
by a medical expert. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Quantum Monte Carlo simulation of a two-dimensional Majorana lattice model,
Abstract: We study interacting Majorana fermions in two dimensions as a low-energy
effective model of a vortex lattice in two-dimensional time-reversal-invariant
topological superconductors. For that purpose, we implement ab-initio quantum
Monte Carlo simulation to the Majorana fermion system in which the
path-integral measure is given by a semi-positive Pfaffian. We discuss
spontaneous breaking of time-reversal symmetry at finite temperature. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Computer Science"
] |
Title: PythonRobotics: a Python code collection of robotics algorithms,
Abstract: This paper describes an Open Source Software (OSS) project: PythonRobotics.
This is a collection of robotics algorithms implemented in the Python
programming language. The focus of the project is on autonomous navigation, and
the goal is for beginners in robotics to understand the basic ideas behind each
algorithm. In this project, the algorithms which are practical and widely used
in both academia and industry are selected. Each sample code is written in
Python3 and only depends on some standard modules for readability and ease of
use. It includes intuitive animations to understand the behavior of the
simulation. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: First On-Site True Gamma-Ray Imaging-Spectroscopy of Contamination near Fukushima Plant,
Abstract: We have developed an Electron Tracking Compton Camera (ETCC), which provides
a well-defined Point Spread Function (PSF) by reconstructing a direction of
each gamma as a point and realizes simultaneous measurement of brightness and
spectrum of MeV gamma-rays for the first time. Here, we present the results of
our on-site pilot gamma-imaging-spectroscopy with ETCC at three contaminated
locations in the vicinity of the Fukushima Daiichi Nuclear Power Plants in
Japan in 2014. The obtained distribution of brightness (or emissivity) with
remote-sensing observations is unambiguously converted into the dose
distribution. We confirm that the dose distribution is consistent with the one
taken by conventional mapping measurements with a dosimeter physically placed
at each grid point. Furthermore, its imaging spectroscopy, boosted by
Compton-edge-free spectra, reveals complex radioactive features in a
quantitative manner around each individual target point in the
background-dominated environment. Notably, we successfully identify a "micro
hot spot" of residual caesium contamination even in an already decontaminated
area. These results show that the ETCC performs exactly as the geometrical
optics predicts, demonstrates its versatility in the field radiation
measurement, and reveals potentials for application in many fields, including
the nuclear industry, medical field, and astronomy. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Quantum Structures in Human Decision-making: Towards Quantum Expected Utility,
Abstract: {\it Ellsberg thought experiments} and empirical confirmation of Ellsberg
preferences pose serious challenges to {\it subjective expected utility theory}
(SEUT). We have recently elaborated a quantum-theoretic framework for human
decisions under uncertainty which satisfactorily copes with the Ellsberg
paradox and other puzzles of SEUT. We apply here the quantum-theoretic
framework to the {\it Ellsberg two-urn example}, showing that the paradox can
be explained by assuming a state change of the conceptual entity that is the
object of the decision ({\it decision-making}, or {\it DM}, {\it entity}) and
representing subjective probabilities by quantum probabilities. We also model
the empirical data we collected in a DM test on human participants within the
theoretic framework above. The obtained results are relevant, as they provide a
line to model real life, e.g., financial and medical, decisions that show the
same empirical patterns as the two-urn experiment. | [
0,
0,
0,
0,
1,
1
] | [
"Physics",
"Quantitative Finance"
] |
Title: A GPU-based Multi-level Algorithm for Boundary Value Problems,
Abstract: A novel and scalable geometric multi-level algorithm is presented for the
numerical solution of elliptic partial differential equations, specially
designed to run with high occupancy of streaming processors inside Graphics
Processing Units(GPUs). The algorithm consists of iterative, superposed
operations on a single grid, and it is composed of two simple full-grid
routines: a restriction and a coarsened interpolation-relaxation. The
restriction is used to collect sources using recursive coarsened averages, and
the interpolation-relaxation simultaneously applies coarsened finite-difference
operators and interpolations. The routines are scheduled in a saw-like refining
cycle. Convergence to machine precision is achieved repeating the full cycle
using accumulated residuals and successively collecting the solution. Its total
number of operations scale linearly with the number of nodes. It provides an
attractive fast solver for Boundary Value Problems (BVPs), specially for
simulations running entirely in the GPU. Applications shown in this work
include the deformation of two-dimensional grids, the computation of
three-dimensional streamlines for a singular trifoil-knot vortex and the
calculation of three-dimensional electric potentials in heterogeneous
dielectric media. | [
1,
1,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics",
"Physics"
] |
Title: Cautious Model Predictive Control using Gaussian Process Regression,
Abstract: Gaussian process (GP) regression has been widely used in supervised machine
learning due to its flexibility and inherent ability to describe uncertainty in
function estimation. In the context of control, it is seeing increasing use for
modeling of nonlinear dynamical systems from data, as it allows the direct
assessment of residual model uncertainty. We present a model predictive control
(MPC) approach that integrates a nominal system with an additive nonlinear part
of the dynamics modeled as a GP. Approximation techniques for propagating the
state distribution are reviewed and we describe a principled way of formulating
the chance constrained MPC problem, which takes into account residual
uncertainties provided by the GP model to enable cautious control. Using
additional approximations for efficient computation, we finally demonstrate the
approach in a simulation example, as well as in a hardware implementation for
autonomous racing of remote controlled race cars, highlighting improvements
with regard to both performance and safety over a nominal controller. | [
1,
0,
1,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Probabilistic Trajectory Segmentation by Means of Hierarchical Dirichlet Process Switching Linear Dynamical Systems,
Abstract: Using movement primitive libraries is an effective means to enable robots to
solve more complex tasks. In order to build these movement libraries, current
algorithms require a prior segmentation of the demonstration trajectories. A
promising approach is to model the trajectory as being generated by a set of
Switching Linear Dynamical Systems and inferring a meaningful segmentation by
inspecting the transition points characterized by the switching dynamics. With
respect to the learning, a nonparametric Bayesian approach is employed
utilizing a Gibbs sampler. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Radio Frequency Interference Mitigation,
Abstract: Radio astronomy observational facilities are under constant upgradation and
development to achieve better capabilities including increasing the time and
frequency resolutions of the recorded data, and increasing the receiving and
recording bandwidth. As only a limited spectrum resource has been allocated to
radio astronomy by the International Telecommunication Union, this results in
the radio observational instrumentation being inevitably exposed to undesirable
radio frequency interference (RFI) signals which originate mainly from
terrestrial human activity and are becoming stronger with time. RFIs degrade
the quality of astronomical data and even lead to data loss. The impact of RFIs
on scientific outcome is becoming progressively difficult to manage. In this
article, we motivate the requirement for RFI mitigation, and review the RFI
characteristics, mitigation techniques and strategies. Mitigation strategies
adopted at some representative observatories, telescopes and arrays are also
introduced. We also discuss and present advantages and shortcomings of the four
classes of RFI mitigation strategies, applicable at the connected causal
stages: preventive, pre-detection, pre-correlation and post-correlation. The
proper identification and flagging of RFI is key to the reduction of data loss
and improvement in data quality, and is also the ultimate goal of developing
RFI mitigation techniques. This can be achieved through a strategy involving a
combination of the discussed techniques in stages. Recent advances in high
speed digital signal processing and high performance computing allow for
performing RFI excision of large data volumes generated from large telescopes
or arrays in both real time and offline modes, aiding the proposed strategy. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Computer Science"
] |
Title: Online Calibration of Phasor Measurement Unit Using Density-Based Spatial Clustering,
Abstract: Data quality of Phasor Measurement Unit (PMU) is receiving increasing
attention as it has been identified as one of the limiting factors that affect
many wide-area measurement system (WAMS) based applications. In general,
existing PMU calibration methods include offline testing and model based
approaches. However, in practice, the effectiveness of both is limited due to
the very strong assumptions employed. This paper presents a novel framework for
online bias error detection and calibration of PMU measurement using
density-based spatial clustering of applications with noise (DBSCAN) based on
much relaxed assumptions. With a new problem formulation, the proposed data
mining based methodology is applicable across a wide spectrum of practical
conditions and one side-product of it is more accurate transmission line
parameters for EMS database and protective relay settings. Case studies
demonstrate the effectiveness of the proposed approach. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Some basic properties of bounded solutions of parabolic equations with p-Laplacian diffusion,
Abstract: We provide a detailed (and fully rigorous) derivation of several fundamental
properties of bounded weak solutions to initial-value problems for general
conservative 2nd-order parabolic equations with p-Laplacian diffusion and
(arbitrary) bounded and integrable initial data. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Bootstrap of residual processes in regression: to smooth or not to smooth ?,
Abstract: In this paper we consider a location model of the form $Y = m(X) +
\varepsilon$, where $m(\cdot)$ is the unknown regression function, the error
$\varepsilon$ is independent of the $p$-dimensional covariate $X$ and
$E(\varepsilon)=0$. Given i.i.d. data $(X_1,Y_1),\ldots,(X_n,Y_n)$ and given an
estimator $\hat m(\cdot)$ of the function $m(\cdot)$ (which can be parametric
or nonparametric of nature), we estimate the distribution of the error term
$\varepsilon$ by the empirical distribution of the residuals $Y_i-\hat m(X_i)$,
$i=1,\ldots,n$. To approximate the distribution of this estimator, Koul and
Lahiri (1994) and Neumeyer (2008, 2009) proposed bootstrap procedures, based on
smoothing the residuals either before or after drawing bootstrap samples. So
far it has been an open question whether a classical non-smooth residual
bootstrap is asymptotically valid in this context. In this paper we solve this
open problem, and show that the non-smooth residual bootstrap is consistent. We
illustrate this theoretical result by means of simulations, that show the
accuracy of this bootstrap procedure for various models, testing procedures and
sample sizes. | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: GANDALF - Graphical Astrophysics code for N-body Dynamics And Lagrangian Fluids,
Abstract: GANDALF is a new hydrodynamics and N-body dynamics code designed for
investigating planet formation, star formation and star cluster problems.
GANDALF is written in C++, parallelised with both OpenMP and MPI and contains a
python library for analysis and visualisation. The code has been written with a
fully object-oriented approach to easily allow user-defined implementations of
physics modules or other algorithms. The code currently contains
implementations of Smoothed Particle Hydrodynamics, Meshless Finite-Volume and
collisional N-body schemes, but can easily be adapted to include additional
particle schemes. We present in this paper the details of its implementation,
results from the test suite, serial and parallel performance results and
discuss the planned future development. The code is freely available as an open
source project on the code-hosting website github at
this https URL and is available under the GPLv2
license. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Computer Science"
] |
Title: Optimal Oil Production and Taxation in Presence of Global Disruptions,
Abstract: This paper studies the optimal extraction policy of an oil field as well as
the efficient taxation of the revenues generated. Taking into account the fact
that the oil price in worldwide commodity markets fluctuates randomly following
global and seasonal macroeconomic parameters, we model the evolution of the oil
price as a mean reverting regime-switching jump diffusion process. Given that
oil producing countries rely on oil sale revenues as well as taxes levied on
oil companies for a good portion of the revenue side of their budgets, we
formulate this problem as a differential game where the two players are the
mining company whose aim is to maximize the revenues generated from its
extracting activities and the government agency in charge of regulating and
taxing natural resources. We prove the existence of a Nash equilibrium and the
convergence of an approximating scheme for the value functions. Furthermore,
optimal extraction and fiscal policies that should be applied when the
equilibrium is reached are derived.A numerical example is presented to
illustrate these results. | [
0,
0,
1,
0,
0,
0
] | [
"Quantitative Finance",
"Mathematics"
] |
Title: Lightweight Multilingual Software Analysis,
Abstract: Developer preferences, language capabilities and the persistence of older
languages contribute to the trend that large software codebases are often
multilingual, that is, written in more than one computer language. While
developers can leverage monolingual software development tools to build
software components, companies are faced with the problem of managing the
resultant large, multilingual codebases to address issues with security,
efficiency, and quality metrics. The key challenge is to address the opaque
nature of the language interoperability interface: one language calling
procedures in a second (which may call a third, or even back to the first),
resulting in a potentially tangled, inefficient and insecure codebase. An
architecture is proposed for lightweight static analysis of large multilingual
codebases: the MLSA architecture. Its modular and table-oriented structure
addresses the open-ended nature of multiple languages and language
interoperability APIs. We focus here as an application on the construction of
call-graphs that capture both inter-language and intra-language calls. The
algorithms for extracting multilingual call-graphs from codebases are
presented, and several examples of multilingual software engineering analysis
are discussed. The state of the implementation and testing of MLSA is
presented, and the implications for future work are discussed. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: Sparse Algorithm for Robust LSSVM in Primal Space,
Abstract: As enjoying the closed form solution, least squares support vector machine
(LSSVM) has been widely used for classification and regression problems having
the comparable performance with other types of SVMs. However, LSSVM has two
drawbacks: sensitive to outliers and lacking sparseness. Robust LSSVM (R-LSSVM)
overcomes the first partly via nonconvex truncated loss function, but the
current algorithms for R-LSSVM with the dense solution are faced with the
second drawback and are inefficient for training large-scale problems. In this
paper, we interpret the robustness of R-LSSVM from a re-weighted viewpoint and
give a primal R-LSSVM by the representer theorem. The new model may have sparse
solution if the corresponding kernel matrix has low rank. Then approximating
the kernel matrix by a low-rank matrix and smoothing the loss function by
entropy penalty function, we propose a convergent sparse R-LSSVM (SR-LSSVM)
algorithm to achieve the sparse solution of primal R-LSSVM, which overcomes two
drawbacks of LSSVM simultaneously. The proposed algorithm has lower complexity
than the existing algorithms and is very efficient for training large-scale
problems. Many experimental results illustrate that SR-LSSVM can achieve better
or comparable performance with less training time than related algorithms,
especially for training large scale problems. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Topological dynamics of gyroscopic and Floquet lattices from Newton's laws,
Abstract: Despite intense interest in realizing topological phases across a variety of
electronic, photonic and mechanical platforms, the detailed microscopic origin
of topological behavior often remains elusive. To bridge this conceptual gap,
we show how hallmarks of topological modes - boundary localization and
chirality - emerge from Newton's laws in mechanical topological systems. We
first construct a gyroscopic lattice with analytically solvable edge modes, and
show how the Lorentz and spring restoring forces conspire to support very
robust "dangling bond" boundary modes. The chirality and locality of these
modes intuitively emerges from microscopic balancing of restoring forces and
cyclotron tendencies. Next, we introduce the highlight of this work, a very
experimentally realistic mechanical non-equilibrium (Floquet) Chern lattice
driven by AC electromagnets. Through appropriate synchronization of the AC
driving protocol, the Floquet lattice is "pushed around" by a rotating
potential analogous to an object washed ashore by water waves. Besides hosting
"dangling bond" chiral modes analogous to the gyroscopic boundary modes, our
Floquet Chern lattice also supports peculiar half-period chiral modes with no
static analog. With key parameters controlled electronically, our setup has the
advantage of being dynamically tunable for applications involving arbitrary
Floquet modulations. The physical intuition gleaned from our two prototypical
topological systems are applicable not just to arbitrarily complicated
mechanical systems, but also photonic and electrical topological setups. | [
0,
1,
1,
0,
0,
0
] | [
"Physics"
] |
Title: Resistivity bound for hydrodynamic bad metals,
Abstract: We obtain a rigorous upper bound on the resistivity $\rho$ of an electron
fluid whose electronic mean free path is short compared to the scale of spatial
inhomogeneities. When such a hydrodynamic electron fluid supports a non-thermal
diffusion process -- such as an imbalance mode between different bands -- we
show that the resistivity bound becomes $\rho \lesssim A \, \Gamma$. The
coefficient $A$ is independent of temperature and inhomogeneity lengthscale,
and $\Gamma$ is a microscopic momentum-preserving scattering rate. In this way
we obtain a unified and novel mechanism -- without umklapp -- for $\rho \sim
T^2$ in a Fermi liquid and the crossover to $\rho \sim T$ in quantum critical
regimes. This behavior is widely observed in transition metal oxides, organic
metals, pnictides and heavy fermion compounds and has presented a longstanding
challenge to transport theory. Our hydrodynamic bound allows phonon
contributions to diffusion constants, including thermal diffusion, to directly
affect the electrical resistivity. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Data Driven Exploratory Attacks on Black Box Classifiers in Adversarial Domains,
Abstract: While modern day web applications aim to create impact at the civilization
level, they have become vulnerable to adversarial activity, where the next
cyber-attack can take any shape and can originate from anywhere. The increasing
scale and sophistication of attacks, has prompted the need for a data driven
solution, with machine learning forming the core of many cybersecurity systems.
Machine learning was not designed with security in mind, and the essential
assumption of stationarity, requiring that the training and testing data follow
similar distributions, is violated in an adversarial domain. In this paper, an
adversary's view point of a classification based system, is presented. Based on
a formal adversarial model, the Seed-Explore-Exploit framework is presented,
for simulating the generation of data driven and reverse engineering attacks on
classifiers. Experimental evaluation, on 10 real world datasets and using the
Google Cloud Prediction Platform, demonstrates the innate vulnerability of
classifiers and the ease with which evasion can be carried out, without any
explicit information about the classifier type, the training data or the
application domain. The proposed framework, algorithms and empirical
evaluation, serve as a white hat analysis of the vulnerabilities, and aim to
foster the development of secure machine learning frameworks. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: The Geodetic Hull Number is Hard for Chordal Graphs,
Abstract: We show the hardness of the geodetic hull number for chordal graphs. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: The cobordism hypothesis,
Abstract: Assuming a conjecture about factorization homology with adjoints, we prove
the cobordism hypothesis, after Baez-Dolan, Costello, Hopkins-Lurie, and Lurie. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: A Latent Variable Model for Two-Dimensional Canonical Correlation Analysis and its Variational Inference,
Abstract: Describing the dimension reduction (DR) techniques by means of probabilistic
models has recently been given special attention. Probabilistic models, in
addition to a better interpretability of the DR methods, provide a framework
for further extensions of such algorithms. One of the new approaches to the
probabilistic DR methods is to preserving the internal structure of data. It is
meant that it is not necessary that the data first be converted from the matrix
or tensor format to the vector format in the process of dimensionality
reduction. In this paper, a latent variable model for matrix-variate data for
canonical correlation analysis (CCA) is proposed. Since in general there is not
any analytical maximum likelihood solution for this model, we present two
approaches for learning the parameters. The proposed methods are evaluated
using the synthetic data in terms of convergence and quality of mappings. Also,
real data set is employed for assessing the proposed methods with several
probabilistic and none-probabilistic CCA based approaches. The results confirm
the superiority of the proposed methods with respect to the competing
algorithms. Moreover, this model can be considered as a framework for further
extensions. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics",
"Mathematics"
] |
Title: Coupled spin-charge dynamics in helical Fermi liquids beyond the random phase approximation,
Abstract: We consider a helical system of fermions with a generic spin (or pseudospin)
orbit coupling. Using the equation of motion approach for the single-particle
distribution functions, and a mean-field decoupling of the higher order
distribution functions, we find a closed form for the charge and spin density
fluctuations in terms of the charge and spin density linear response functions.
Approximating the nonlocal exchange term with a Hubbard-like local-field
factor, we obtain coupled spin and charge density response matrix beyond the
random phase approximation, whose poles give the dispersion of four collective
spin-charge modes. We apply our generic technique to the well-explored
two-dimensional system with Rashba spin-orbit coupling and illustrate how it
gives results for the collective modes, Drude weight, and spin-Hall
conductivity which are in very good agreement with the results obtained from
other more sophisticated approaches. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: SAML-QC: a Stochastic Assessment and Machine Learning based QC technique for Industrial Printing,
Abstract: Recently, the advancement in industrial automation and high-speed printing
has raised numerous challenges related to the printing quality inspection of
final products. This paper proposes a machine vision based technique to assess
the printing quality of text on industrial objects. The assessment is based on
three quality defects such as text misalignment, varying printing shades, and
misprinted text. The proposed scheme performs the quality inspection through
stochastic assessment technique based on the second-order statistics of
printing. First: the text-containing area on printed product is identified
through image processing techniques. Second: the alignment testing of the
identified text-containing area is performed. Third: optical character
recognition is performed to divide the text into different small boxes and only
the intensity value of each text-containing box is taken as a random variable
and second-order statistics are estimated to determine the varying printing
defects in the text under one, two and three sigma thresholds. Fourth: the
K-Nearest Neighbors based supervised machine learning is performed to provide
the stochastic process for misprinted text detection. Finally, the technique is
deployed on an industrial image for the printing quality assessment with
varying values of n and m. The results have shown that the proposed SAML-QC
technique can perform real-time automated inspection for industrial printing. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Highly sensitive atomic based MW interferometry,
Abstract: We theoretically study a scheme to develop an atomic based MW interferometry
using the Rydberg states in Rb. Unlike the traditional MW interferometry, this
scheme is not based upon the electrical circuits, hence the sensitivity of the
phase and the amplitude/strength of the MW field is not limited by the Nyquist
thermal noise. Further this system has great advantage due to its very high
bandwidth, ranging from radio frequency (RF), micro wave (MW) to terahertz
regime. In addition, this is \textbf{orders of magnitude} more sensitive to
field strength as compared to the prior demonstrations on the MW electrometry
using the Rydberg atomic states. However previously studied atomic systems are
only sensitive to the field strength but not to the phase and hence this scheme
provides a great opportunity to characterize the MW completely including the
propagation direction and the wavefront. This study opens up a new dimension in
the Radar technology such as in synthetic aperture radar interferometry. The MW
interferometry is based upon a six-level loopy ladder system involving the
Rydberg states in which two sub-systems interfere constructively or
destructively depending upon the phase between the MW electric fields closing
the loop. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: The Wisdom of a Kalman Crowd,
Abstract: The Kalman Filter has been called one of the greatest inventions in
statistics during the 20th century. Its purpose is to measure the state of a
system by processing the noisy data received from different electronic sensors.
In comparison, a useful resource for managers in their effort to make the right
decisions is the wisdom of crowds. This phenomenon allows managers to combine
judgments by different employees to get estimates that are often more accurate
and reliable than estimates, which managers produce alone. Since harnessing the
collective intelligence of employees, and filtering signals from multiple noisy
sensors appear related, we looked at the possibility of using the Kalman Filter
on estimates by people. Our predictions suggest, and our findings based on the
Survey of Professional Forecasters reveal, that the Kalman Filter can help
managers solve their decision-making problems by giving them stronger signals
before they choose. Indeed, when used on a subset of forecasters identified by
the Contribution Weighted Model, the Kalman Filter beat that rule clearly,
across all the forecasting horizons in the survey. | [
0,
0,
0,
0,
0,
1
] | [
"Statistics",
"Computer Science"
] |
Title: Noisy independent component analysis of auto-correlated components,
Abstract: We present a new method for the separation of superimposed, independent,
auto-correlated components from noisy multi-channel measurement. The presented
method simultaneously reconstructs and separates the components, taking all
channels into account and thereby increases the effective signal-to-noise ratio
considerably, allowing separations even in the high noise regime.
Characteristics of the measurement instruments can be included, allowing for
application in complex measurement situations. Independent posterior samples
can be provided, permitting error estimates on all desired quantities. Using
the concept of information field theory, the algorithm is not restricted to any
dimensionality of the underlying space or discretization scheme thereof. | [
0,
1,
0,
1,
0,
0
] | [
"Statistics",
"Mathematics",
"Computer Science"
] |
Title: Bayesian Renewables Scenario Generation via Deep Generative Networks,
Abstract: We present a method to generate renewable scenarios using Bayesian
probabilities by implementing the Bayesian generative adversarial
network~(Bayesian GAN), which is a variant of generative adversarial networks
based on two interconnected deep neural networks. By using a Bayesian
formulation, generators can be constructed and trained to produce scenarios
that capture different salient modes in the data, allowing for better diversity
and more accurate representation of the underlying physical process. Compared
to conventional statistical models that are often hard to scale or sample from,
this method is model-free and can generate samples extremely efficiently. For
validation, we use wind and solar times-series data from NREL integration data
sets to train the Bayesian GAN. We demonstrate that proposed method is able to
generate clusters of wind scenarios with different variance and mean value, and
is able to distinguish and generate wind and solar scenarios simultaneously
even if the historical data are intentionally mixed. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics",
"Quantitative Finance"
] |
Title: Krylov Subspace Recycling for Fast Iterative Least-Squares in Machine Learning,
Abstract: Solving symmetric positive definite linear problems is a fundamental
computational task in machine learning. The exact solution, famously, is
cubicly expensive in the size of the matrix. To alleviate this problem, several
linear-time approximations, such as spectral and inducing-point methods, have
been suggested and are now in wide use. These are low-rank approximations that
choose the low-rank space a priori and do not refine it over time. While this
allows linear cost in the data-set size, it also causes a finite, uncorrected
approximation error. Authors from numerical linear algebra have explored ways
to iteratively refine such low-rank approximations, at a cost of a small number
of matrix-vector multiplications. This idea is particularly interesting in the
many situations in machine learning where one has to solve a sequence of
related symmetric positive definite linear problems. From the machine learning
perspective, such deflation methods can be interpreted as transfer learning of
a low-rank approximation across a time-series of numerical tasks. We study the
use of such methods for our field. Our empirical results show that, on
regression and classification problems of intermediate size, this approach can
interpolate between low computational cost and numerical precision. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Towards a Physical Oracle for the Partition Problem using Analogue Computing,
Abstract: Despite remarkable achievements in its practical tractability, the notorious
class of NP-complete problems has been escaping all attempts to find a
worst-case polynomial time-bound solution algorithms for any of them. The vast
majority of work relies on Turing machines or equivalent models, all of which
relate to digital computing. This raises the question of whether a computer
that is (partly) non-digital could offer a new door towards an efficient
solution. And indeed, the partition problem, which is another NP-complete
sibling of the famous Boolean satisfiability problem SAT, might be open to
efficient solutions using analogue computing. We investigate this hypothesis
here, providing experimental evidence that Partition, and in turn also SAT, may
become tractable on a combined digital and analogue computing machine. This
work provides mostly theoretical and based on simulations, and as such does not
exhibit a polynomial time algorithm to solve NP-complete problems. Instead, it
is intended as a pointer to new directions of research on special-purpose
computing architectures that may help handling the class NP efficiently. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Physics"
] |
Title: On a representation of fractional Brownian motion and the limit distributions of statistics arising in cusp statistical models,
Abstract: We discuss some extensions of results from the recent paper by Chernoyarov et
al. (Ann. Inst. Stat. Math., October 2016) concerning limit distributions of
Bayesian and maximum likelihood estimators in the model "signal plus white
noise" with irregular cusp-type signals. Using a new representation of
fractional Brownian motion (fBm) in terms of cusp functions we show that as the
noise intensity tends to zero, the limit distributions are expressed in terms
of fBm for the full range of asymmetric cusp-type signals correspondingly with
the Hurst parameter H, 0<H<1. Simulation results for the densities and
variances of the limit distributions of Bayesian and maximum likelihood
estimators are also provided. | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: Grafting for Combinatorial Boolean Model using Frequent Itemset Mining,
Abstract: This paper introduces the combinatorial Boolean model (CBM), which is defined
as the class of linear combinations of conjunctions of Boolean attributes. This
paper addresses the issue of learning CBM from labeled data. CBM is of high
knowledge interpretability but naïve learning of it requires exponentially
large computation time with respect to data dimension and sample size. To
overcome this computational difficulty, we propose an algorithm GRAB (GRAfting
for Boolean datasets), which efficiently learns CBM within the
$L_1$-regularized loss minimization framework. The key idea of GRAB is to
reduce the loss minimization problem to the weighted frequent itemset mining,
in which frequent patterns are efficiently computable. We employ benchmark
datasets to empirically demonstrate that GRAB is effective in terms of
computational efficiency, prediction accuracy and knowledge discovery. | [
1,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Dissipativity Theory for Accelerating Stochastic Variance Reduction: A Unified Analysis of SVRG and Katyusha Using Semidefinite Programs,
Abstract: Techniques for reducing the variance of gradient estimates used in stochastic
programming algorithms for convex finite-sum problems have received a great
deal of attention in recent years. By leveraging dissipativity theory from
control, we provide a new perspective on two important variance-reduction
algorithms: SVRG and its direct accelerated variant Katyusha. Our perspective
provides a physically intuitive understanding of the behavior of SVRG-like
methods via a principle of energy conservation. The tools discussed here allow
us to automate the convergence analysis of SVRG-like methods by capturing their
essential properties in small semidefinite programs amenable to standard
analysis and computational techniques. Our approach recovers existing
convergence results for SVRG and Katyusha and generalizes the theory to
alternative parameter choices. We also discuss how our approach complements the
linear coupling technique. Our combination of perspectives leads to a better
understanding of accelerated variance-reduced stochastic methods for finite-sum
problems. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Entire Solution in an Ignition Nonlocal Dispersal Equation: Asymmetric Kernel,
Abstract: This paper mainly focus on the front-like entire solution of a classical
nonlocal dispersal equation with ignition nonlinearity. Especially, the
dispersal kernel function $J$ may not be symmetric here. The asymmetry of $J$
has a great influence on the profile of the traveling waves and the sign of the
wave speeds, which further makes the properties of the entire solution more
diverse. We first investigate the asymptotic behavior of the traveling wave
solutions since it plays an essential role in obtaining the front-like entire
solution. Due to the impact of $f'(0)=0$, we can no longer use the common
method which mainly depending on Ikehara theorem and bilateral Laplace
transform to study the asymptotic rates of the nondecreasing traveling wave and
the nonincreasing one tending to 0, respectively, thus we adopt another method
to investigate them. Afterwards, we establish a new entire solution and obtain
its qualitative properties by constructing proper supersolution and subsolution
and by classifying the sign and size of the wave speeds. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Making up for the deficit in a marathon run,
Abstract: To predict the final result of an athlete in a marathon run thoroughly is the
eternal desire of each trainer. Usually, the achieved result is weaker than the
predicted one due to the objective (e.g., environmental conditions) as well as
subjective factors (e.g., athlete's malaise). Therefore, making up for the
deficit between predicted and achieved results is the main ingredient of the
analysis performed by trainers after the competition. In the analysis, they
search for parts of a marathon course where the athlete lost time. This paper
proposes an automatic making up for the deficit by using a Differential
Evolution algorithm. In this case study, the results that were obtained by a
wearable sports-watch by an athlete in a real marathon are analyzed. The first
experiments with Differential Evolution show the possibility of using this
method in the future. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: Dynamics of the spin-1/2 Heisenberg chain initialized in a domain-wall state,
Abstract: We study the dynamics of an isotropic spin-1/2 Heisenberg chain starting in a
domain-wall initial condition, where the spins are initially up on the left
half-line and down on the right half-line. We focus on the long-time behavior
of the magnetization profile. We perform extensive time-dependent
density-matrix renormalization group simulations (up to t=350) and find that
the data are compatible with a diffusive behavior. Subleading corrections decay
slowly blurring the emergence of the diffusive behavior. We also compare our
results with two alternative scenarios: superdiffusive behavior and enhanced
diffusion with a logarithmic correction. We finally discuss the evolution of
the entanglement entropy. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Simple Necessary Conditions for the Existence of a Hamiltonian Path with Applications to Cactus Graphs,
Abstract: We describe some necessary conditions for the existence of a Hamiltonian path
in any graph (in other words, for a graph to be traceable). These conditions
result in a linear time algorithm to decide the Hamiltonian path problem for
cactus graphs. We apply this algorithm to several molecular databases to report
the numbers of graphs that are traceable cactus graphs. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Implementation of the Bin Hierarchy Method for restoring a smooth function from a sampled histogram,
Abstract: We present $\texttt{BHM}$, a tool for restoring a smooth function from a
sampled histogram using the bin hierarchy method. The theoretical background of
the method is presented in [arXiv:1707.07625]. The code automatically generates
a smooth polynomial spline with the minimal acceptable number of knots from the
input data. It works universally for any sufficiently regular shaped
distribution and any level of data quality, requiring almost no external
parameter specification. It is particularly useful for large-scale numerical
data analysis. This paper explains the details of the implementation and the
use of the program. | [
0,
1,
0,
1,
0,
0
] | [
"Computer Science",
"Statistics"
] |
Title: An invitation to model theory and C*-algebras,
Abstract: We present an introductory survey to first order logic for metric structures
and its applications to C*-algebras. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Analytical and simulation studies of pedestrian flow at a crossing with random update rule,
Abstract: The intersecting pedestrian flow on the 2D lattice with random update rule is
studied. Each pedestrian has three moving directions without the back step.
Under periodic boundary conditions, an intermediate phase has been found at
which some pedestrians could move along the border of jamming stripes. We have
performed mean field analysis for the moving and intermediate phase
respectively. The analytical results agree with the simulation results well.
The empty site moves along the interface of jamming stripes when the system
only has one empty site. The average movement of empty site in one Monte Carlo
step (MCS) has been analyzed through the master equation. Under open boundary
conditions, the system exhibits moving and jamming phases. The critical
injection probability $\alpha_c$ shows nontrivially against the forward moving
probability $q$. The analytical results of average velocity, the density and
the flow rate against the injection probability in the moving phase also agree
with simulation results well. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: VB-Courant algebroids, E-Courant algebroids and generalized geometry,
Abstract: In this paper, we first discuss the relation between VB-Courant algebroids
and E-Courant algebroids and construct some examples of E-Courant algebroids.
Then we introduce the notion of a generalized complex structure on an E-Courant
algebroid, unifying the usual generalized complex structures on
even-dimensional manifolds and generalized contact structures on
odd-dimensional manifolds. Moreover, we study generalized complex structures on
an omni-Lie algebroid in detail. In particular, we show that generalized
complex structures on an omni-Lie algebra $\gl(V)\oplus V$ correspond to
complex Lie algebra structures on V. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Topological boundary invariants for Floquet systems and quantum walks,
Abstract: A Floquet systems is a periodically driven quantum system. It can be
described by a Floquet operator. If this unitary operator has a gap in the
spectrum, then one can define associated topological bulk invariants which can
either only depend on the bands of the Floquet operator or also on the time as
a variable. It is shown how a K-theoretic result combined with the
bulk-boundary correspondence leads to edge invariants for the half-space
Floquet operators. These results also apply to topological quantum walks. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: xSDK Foundations: Toward an Extreme-scale Scientific Software Development Kit,
Abstract: Extreme-scale computational science increasingly demands multiscale and
multiphysics formulations. Combining software developed by independent groups
is imperative: no single team has resources for all predictive science and
decision support capabilities. Scientific libraries provide high-quality,
reusable software components for constructing applications with improved
robustness and portability. However, without coordination, many libraries
cannot be easily composed. Namespace collisions, inconsistent arguments, lack
of third-party software versioning, and additional difficulties make
composition costly.
The Extreme-scale Scientific Software Development Kit (xSDK) defines
community policies to improve code quality and compatibility across
independently developed packages (hypre, PETSc, SuperLU, Trilinos, and
Alquimia) and provides a foundation for addressing broader issues in software
interoperability, performance portability, and sustainability. The xSDK
provides turnkey installation of member software and seamless combination of
aggregate capabilities, and it marks first steps toward extreme-scale
scientific software ecosystems from which future applications can be composed
rapidly with assured quality and scalability. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science"
] |
Title: On stabilization of solutions of nonlinear parabolic equations with a gradient term,
Abstract: For parabolic equations of the form $$ \frac{\partial u}{\partial t} -
\sum_{i,j=1}^n a_{ij} (x, u) \frac{\partial^2 u}{\partial x_i \partial x_j} + f
(x, u, D u) = 0 \quad \mbox{in } {\mathbb R}_+^{n+1}, $$ where ${\mathbb
R}_+^{n+1} = {\mathbb R}^n \times (0, \infty)$, $n \ge 1$, $D = (\partial /
\partial x_1, \ldots, \partial / \partial x_n)$ is the gradient operator, and
$f$ is some function, we obtain conditions guaranteeing that every solution
tends to zero as $t \to \infty$. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: Deep metric learning for multi-labelled radiographs,
Abstract: Many radiological studies can reveal the presence of several co-existing
abnormalities, each one represented by a distinct visual pattern. In this
article we address the problem of learning a distance metric for plain
radiographs that captures a notion of "radiological similarity": two chest
radiographs are considered to be similar if they share similar abnormalities.
Deep convolutional neural networks (DCNs) are used to learn a low-dimensional
embedding for the radiographs that is equipped with the desired metric. Two
loss functions are proposed to deal with multi-labelled images and potentially
noisy labels. We report on a large-scale study involving over 745,000 chest
radiographs whose labels were automatically extracted from free-text
radiological reports through a natural language processing system. Using 4,500
validated exams, we demonstrate that the methodology performs satisfactorily on
clustering and image retrieval tasks. Remarkably, the learned metric separates
normal exams from those having radiological abnormalities. | [
0,
0,
0,
1,
0,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Fully-Dynamic and Kinetic Conflict-Free Coloring of Intervals with Respect to Points,
Abstract: We introduce the fully-dynamic conflict-free coloring problem for a set $S$
of intervals in $\mathbb{R}^1$ with respect to points, where the goal is to
maintain a conflict-free coloring for$S$ under insertions and deletions. A
coloring is conflict-free if for each point $p$ contained in some interval, $p$
is contained in an interval whose color is not shared with any other interval
containing $p$. We investigate trade-offs between the number of colors used and
the number of intervals that are recolored upon insertion or deletion of an
interval. Our results include:
- a lower bound on the number of recolorings as a function of the number of
colors, which implies that with $O(1)$ recolorings per update the worst-case
number of colors is $\Omega(\log n/\log\log n)$, and that any strategy using
$O(1/\varepsilon)$ colors needs $\Omega(\varepsilon n^{\varepsilon})$
recolorings;
- a coloring strategy that uses $O(\log n)$ colors at the cost of $O(\log n)$
recolorings, and another strategy that uses $O(1/\varepsilon)$ colors at the
cost of $O(n^{\varepsilon}/\varepsilon)$ recolorings;
- stronger upper and lower bounds for special cases.
We also consider the kinetic setting where the intervals move continuously
(but there are no insertions or deletions); here we show how to maintain a
coloring with only four colors at the cost of three recolorings per event and
show this is tight. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Oscillating dipole with fractional quantum source in Aharonov-Bohm electrodynamics,
Abstract: We show, in the case of a special dipolar source, that electromagnetic fields
in fractional quantum mechanics have an unexpected space dependence:
propagating fields may have non-transverse components, and the distinction
between near-field zone and wave zone is blurred. We employ an extension of
Maxwell theory, Aharonov-Bohm electrodynamics, which is compatible with
currents $j^\nu$ conserved globally but not locally, we have derived in another
work the field equation $\partial_\mu F^{\mu \nu}=j^\nu+i^\nu$, where $i^\nu$
is a non-local function of $j^\nu$, called "secondary current". Y.\ Wei has
recently proved that the probability current in fractional quantum mechanics is
in general not locally conserved. We compute this current for a Gaussian wave
packet with fractional parameter $a=3/2$ and find that in a suitable limit it
can be approximated by our simplified dipolar source. Currents which are not
locally conserved may be present also in other quantum systems whose wave
functions satisfy non-local equations. The combined electromagnetic effects of
such sources and their secondary currents are very interesting both
theoretically and for potential applications. | [
0,
1,
0,
0,
0,
0
] | [
"Physics"
] |
Title: Randomized Linear Programming Solves the Discounted Markov Decision Problem In Nearly-Linear (Sometimes Sublinear) Running Time,
Abstract: We propose a novel randomized linear programming algorithm for approximating
the optimal policy of the discounted Markov decision problem. By leveraging the
value-policy duality and binary-tree data structures, the algorithm adaptively
samples state-action-state transitions and makes exponentiated primal-dual
updates. We show that it finds an $\epsilon$-optimal policy using nearly-linear
run time in the worst case. When the Markov decision process is ergodic and
specified in some special data formats, the algorithm finds an
$\epsilon$-optimal policy using run time linear in the total number of
state-action pairs, which is sublinear in the input size. These results provide
a new venue and complexity benchmarks for solving stochastic dynamic programs. | [
1,
0,
1,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |
Title: Inference For High-Dimensional Split-Plot-Designs: A Unified Approach for Small to Large Numbers of Factor Levels,
Abstract: Statisticians increasingly face the problem to reconsider the adaptability of
classical inference techniques. In particular, divers types of high-dimensional
data structures are observed in various research areas; disclosing the
boundaries of conventional multivariate data analysis. Such situations occur,
e.g., frequently in life sciences whenever it is easier or cheaper to
repeatedly generate a large number $d$ of observations per subject than
recruiting many, say $N$, subjects. In this paper we discuss inference
procedures for such situations in general heteroscedastic split-plot designs
with $a$ independent groups of repeated measurements. These will, e.g., be able
to answer questions about the occurrence of certain time, group and
interactions effects or about particular profiles.
The test procedures are based on standardized quadratic forms involving
suitably symmetrized U-statistics-type estimators which are robust against an
increasing number of dimensions $d$ and/or groups $a$. We then discuss its
limit distributions in a general asymptotic framework and additionally propose
improved small sample approximations. Finally its small sample performance is
investigated in simulations and the applicability is illustrated by a real data
analysis. | [
0,
0,
1,
1,
0,
0
] | [
"Statistics",
"Mathematics"
] |
Title: Trail-Mediated Self-Interaction,
Abstract: A number of microorganisms leave persistent trails while moving along
surfaces. For single-cell organisms, the trail-mediated self-interaction will
influence its dynamics. It has been discussed recently [Kranz \textit{et al.}
Phys. Rev. Lett. \textbf{117}, 8101 (2016)] that the self-interaction may
localize the organism above a critical coupling $\chi_c$ to the trail. Here we
will derive a generalized active particle model capturing the key features of
the self-interaction and analyze its behavior for smaller couplings $\chi <
\chi_c$. We find that fluctuations in propulsion speed shift the localization
transition to stronger couplings. | [
0,
0,
0,
0,
1,
0
] | [
"Physics",
"Quantitative Biology"
] |
Title: Summability properties of Gabor expansions,
Abstract: We show that there exist complete and minimal systems of time-frequency
shifts of Gaussians in $L^2(\mathbb{R})$ which are not strong Markushevich
basis (do not admit the spectral synthesis). In particular, it implies that
there is no linear summation method for general Gaussian Gabor expansions. On
the other hand we prove that the spectral synthesis for such Gabor systems
holds up to one dimensional defect. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics"
] |
Title: On thin local sets of the Gaussian free field,
Abstract: We study how small a local set of the continuum Gaussian free field (GFF) in
dimension $d$ has to be to ensure that this set is thin, which loosely speaking
means that it captures no GFF mass on itself, in other words, that the field
restricted to it is zero. We provide a criterion on the size of the local set
for this to happen, and on the other hand, we show that this criterion is sharp
by constructing small local sets that are not thin. | [
0,
0,
1,
0,
0,
0
] | [
"Mathematics",
"Physics"
] |
Title: Dihedral angle prediction using generative adversarial networks,
Abstract: Several dihedral angles prediction methods were developed for protein
structure prediction and their other applications. However, distribution of
predicted angles would not be similar to that of real angles. To address this
we employed generative adversarial networks (GAN). Generative adversarial
networks are composed of two adversarially trained networks: a discriminator
and a generator. A discriminator distinguishes samples from a dataset and
generated samples while a generator generates realistic samples. Although the
discriminator of GANs is trained to estimate density, GAN model is intractable.
On the other hand, noise-contrastive estimation (NCE) was introduced to
estimate a normalization constant of an unnormalized statistical model and thus
the density function. In this thesis, we introduce noise-contrastive estimation
generative adversarial networks (NCE-GAN) which enables explicit density
estimation of a GAN model. And a new loss for the generator is proposed. We
also propose residue-wise variants of auxiliary classifier GAN (AC-GAN) and
Semi-supervised GAN to handle sequence information in a window. In our
experiment, the conditional generative adversarial network (C-GAN), AC-GAN and
Semi-supervised GAN were compared. And experiments done with improved
conditions were invested. We identified a phenomenon of AC-GAN that
distribution of its predicted angles is composed of unusual clusters. The
distribution of the predicted angles of Semi-supervised GAN was most similar to
the Ramachandran plot. We found that adding the output of the NCE as an
additional input of the discriminator is helpful to stabilize the training of
the GANs and to capture the detailed structures. Adding regression loss and
using predicted angles by regression loss only model could improve the
conditional generation performance of the C-GAN and AC-GAN. | [
0,
0,
0,
1,
1,
0
] | [
"Computer Science",
"Quantitative Biology"
] |
Title: Theoretical Analysis of Generalized Sagnac Effect in the Standard Synchronization,
Abstract: The Sagnac effect has been shown in inertial frames as well as rotating
frames. We solve the problem of the generalized Sagnac effect in the standard
synchronization of clocks. The speed of a light beam that traverses an optical
fiber loop is measured with respect to the proper time of the light detector,
and is shown to be other than the constant c, though it appears to be c if
measured by the time standard-synchronized. The fiber loop, which can have an
arbitrary shape, is described by an infinite number of straight lines such that
it can be handled by the general framework of Mansouri and Sexl (MS). For a
complete analysis of the Sagnac effect, the motion of the laboratory should be
taken into account. The MS framework is introduced to deal with its motion
relative to a preferred reference frame. Though the one-way speed of light is
other than c, its two-way speed is shown to be c with respect to the proper
time. The theoretical analysis of the generalized Sagnac effect corresponds to
the experimental results, and shows the usefulness of the standard
synchronization. The introduction of the standard synchrony can make
mathematical manipulation easy and can allow us to deal with relative motions
between inertial frames without information on their velocities relative to the
preferred frame. | [
0,
1,
0,
0,
0,
0
] | [
"Physics",
"Mathematics"
] |
Title: Learning Heuristic Search via Imitation,
Abstract: Robotic motion planning problems are typically solved by constructing a
search tree of valid maneuvers from a start to a goal configuration. Limited
onboard computation and real-time planning constraints impose a limit on how
large this search tree can grow. Heuristics play a crucial role in such
situations by guiding the search towards potentially good directions and
consequently minimizing search effort. Moreover, it must infer such directions
in an efficient manner using only the information uncovered by the search up
until that time. However, state of the art methods do not address the problem
of computing a heuristic that explicitly minimizes search effort. In this
paper, we do so by training a heuristic policy that maps the partial
information from the search to decide which node of the search tree to expand.
Unfortunately, naively training such policies leads to slow convergence and
poor local minima. We present SaIL, an efficient algorithm that trains
heuristic policies by imitating "clairvoyant oracles" - oracles that have full
information about the world and demonstrate decisions that minimize search
effort. We leverage the fact that such oracles can be efficiently computed
using dynamic programming and derive performance guarantees for the learnt
heuristic. We validate the approach on a spectrum of environments which show
that SaIL consistently outperforms state of the art algorithms. Our approach
paves the way forward for learning heuristics that demonstrate an anytime
nature - finding feasible solutions quickly and incrementally refining it over
time. | [
1,
0,
0,
0,
0,
0
] | [
"Computer Science",
"Mathematics"
] |