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17,101 | Ideal Cluster Points in Topological Spaces | Given an ideal $\mathcal{I}$ on $\omega$, we show that a sequence in a
topological space $X$ is $\mathcal{I}$-convergent if and only if there exists a
"big" $\mathcal{I}$-convergent subsequence. In addition, we study several
properties of $\mathcal{I}$-cluster points. As a consequence, the underlying
topology $\tau$ coincides with the topology generated by the pair
$(\tau,\mathcal{I})$. Then, we obtain two characterizations of the set of
$\mathcal{I}$-cluster points as classical cluster points of a filters on $X$
and as the smallest closed set containing "almost all" the sequence.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,102 | Spin Hall effect of gravitational waves | Gravitons possess a Berry curvature due to their helicity. We derive the
semiclassical equations of motion for gravitons taking into account the Berry
curvature. We show that this quantum correction leads to the splitting of the
trajectories of right- and left-handed gravitational waves in curved space, and
that this correction can be understood as a topological phenomenon. This is the
spin Hall effect (SHE) of gravitational waves. We find that the SHE of
gravitational waves is twice as large as that of light. Possible future
observations of the SHE of gravitational waves can potentially test the quantum
nature of gravitons beyond the classical general relativity.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,103 | Many-Goals Reinforcement Learning | All-goals updating exploits the off-policy nature of Q-learning to update all
possible goals an agent could have from each transition in the world, and was
introduced into Reinforcement Learning (RL) by Kaelbling (1993). In prior work
this was mostly explored in small-state RL problems that allowed tabular
representations and where all possible goals could be explicitly enumerated and
learned separately. In this paper we empirically explore 3 different extensions
of the idea of updating many (instead of all) goals in the context of RL with
deep neural networks (or DeepRL for short). First, in a direct adaptation of
Kaelbling's approach we explore if many-goals updating can be used to achieve
mastery in non-tabular visual-observation domains. Second, we explore whether
many-goals updating can be used to pre-train a network to subsequently learn
faster and better on a single main task of interest. Third, we explore whether
many-goals updating can be used to provide auxiliary task updates in training a
network to learn faster and better on a single main task of interest. We
provide comparisons to baselines for each of the 3 extensions.
| 0 | 0 | 0 | 1 | 0 | 0 |
17,104 | Localized Structured Prediction | Key to structured prediction is exploiting the problem structure to simplify
the learning process. A major challenge arises when data exhibit a local
structure (e.g., are made by "parts") that can be leveraged to better
approximate the relation between (parts of) the input and (parts of) the
output. Recent literature on signal processing, and in particular computer
vision, has shown that capturing these aspects is indeed essential to achieve
state-of-the-art performance. While such algorithms are typically derived on a
case-by-case basis, in this work we propose the first theoretical framework to
deal with part-based data from a general perspective. We derive a novel
approach to deal with these problems and study its generalization properties
within the setting of statistical learning theory. Our analysis is novel in
that it explicitly quantifies the benefits of leveraging the part-based
structure of the problem with respect to the learning rates of the proposed
estimator.
| 0 | 0 | 0 | 1 | 0 | 0 |
17,105 | Routing in FRET-based Nanonetworks | Nanocommunications, understood as communications between nanoscale devices,
is commonly regarded as a technology essential for cooperation of large groups
of nanomachines and thus crucial for development of the whole area of
nanotechnology. While solutions for point-to-point nanocommunications have been
already proposed, larger networks cannot function properly without routing. In
this article we focus on the nanocommunications via Forster Resonance Energy
Transfer (FRET), which was found to be a technique with a very high signal
propagation speed, and discuss how to route signals through nanonetworks. We
introduce five new routing mechanisms, based on biological properties of
specific molecules. We experimentally validate one of these mechanisms.
Finally, we analyze open issues showing the technical challenges for signal
transmission and routing in FRET-based nanocommunications.
| 0 | 0 | 0 | 0 | 1 | 0 |
17,106 | FFT Convolutions are Faster than Winograd on Modern CPUs, Here is Why | Winograd-based convolution has quickly gained traction as a preferred
approach to implement convolutional neural networks (ConvNet) on various
hardware platforms because it requires fewer floating point operations than
FFT-based or direct convolutions.
This paper compares three highly optimized implementations (regular FFT--,
Gauss--FFT--, and Winograd--based convolutions) on modern multi-- and
many--core CPUs. Although all three implementations employed the same
optimizations for modern CPUs, our experimental results with two popular
ConvNets (VGG and AlexNet) show that the FFT--based implementations generally
outperform the Winograd--based approach, contrary to the popular belief.
To understand the results, we use a Roofline performance model to analyze the
three implementations in detail, by looking at each of their computation phases
and by considering not only the number of floating point operations, but also
the memory bandwidth and the cache sizes. The performance analysis explains
why, and under what conditions, the FFT--based implementations outperform the
Winograd--based one, on modern CPUs.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,107 | The application of selection principles in the study of the properties of function spaces | In this paper we investigate the properties of function spaces using the
selection principles.
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17,108 | Progressive Neural Architecture Search | We propose a new method for learning the structure of convolutional neural
networks (CNNs) that is more efficient than recent state-of-the-art methods
based on reinforcement learning and evolutionary algorithms. Our approach uses
a sequential model-based optimization (SMBO) strategy, in which we search for
structures in order of increasing complexity, while simultaneously learning a
surrogate model to guide the search through structure space. Direct comparison
under the same search space shows that our method is up to 5 times more
efficient than the RL method of Zoph et al. (2018) in terms of number of models
evaluated, and 8 times faster in terms of total compute. The structures we
discover in this way achieve state of the art classification accuracies on
CIFAR-10 and ImageNet.
| 1 | 0 | 0 | 1 | 0 | 0 |
17,109 | Lower Bounds for Maximum Gap in (Inverse) Cyclotomic Polynomials | The maximum gap $g(f)$ of a polynomial $f$ is the maximum of the differences
(gaps) between two consecutive exponents that appear in $f$. Let $\Phi_{n}$ and
$\Psi_{n}$ denote the $n$-th cyclotomic and $n$-th inverse cyclotomic
polynomial, respectively. In this paper, we give several lower bounds for
$g(\Phi_{n})$ and $g(\Psi_{n})$, where $n$ is the product of odd primes. We
observe that they are very often exact. We also give an exact expression for
$g(\Psi_{n})$ under a certain condition. Finally we conjecture an exact
expression for $g(\Phi_{n})$ under a certain condition.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,110 | Dynamical Analysis of Cylindrically Symmetric Anisotropic Sources in $f(R,T)$ Gravity | In this paper, we have analyzed the stability of cylindrically symmetric
collapsing object filled with locally anisotropic fluid in $f(R,T)$ theory,
where $R$ is the scalar curvature and $T$ is the trace of stress-energy tensor
of matter. Modified field equations and dynamical equations are constructed in
$f(R,T)$ gravity. Evolution or collapse equation is derived from dynamical
equations by performing linear perturbation on them. Instability range is
explored in both Newtonian and post-Newtonian regimes with the help of
adiabetic index, which defines the impact of physical parameters on the
instability range. Some conditions are imposed on physical quantities to secure
the stability of the gravitating sources.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,111 | Trace and Kunneth formulas for singularity categories and applications | We present an $\ell$-adic trace formula for saturated and admissible
dg-categories over a base monoidal dg-category. Moreover, we prove Künneth
formulas for dg-category of singularities, and for inertia-invariant vanishing
cycles. As an application, we prove a version of Bloch's Conductor Conjecture
(stated by Spencer Bloch in 1985), under the additional hypothesis that the
monodromy action of the inertia group is unipotent.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,112 | A Redshift Survey of the Nearby Galaxy Cluster Abell 2199: Comparison of the Spatial and Kinematic Distributions of Galaxies with the Intracluster Medium | We present the results from an extensive spectroscopic survey of the central
region of the nearby galaxy cluster Abell 2199 at $z=0.03$. By combining 775
new redshifts from the MMT/Hectospec observations with the data in the
literature, we construct a large sample of 1624 galaxies with measured
redshifts at $R<30^\prime$, which results in high spectroscopic completeness at
$r_{\rm petro,0}<20.5$ (77%). We use these data to study the kinematics and
clustering of galaxies focusing on the comparison with those of the
intracluster medium (ICM) from Suzaku X-ray observations. We identify 406
member galaxies of A2199 at $R<30^\prime$ using the caustic technique. The
velocity dispersion profile of cluster members appears smoothly connected to
the stellar velocity dispersion profile of the cD galaxy. The luminosity
function is well fitted with a Schechter function at $M_r<-15$. The radial
velocities of cluster galaxies generally agree well with those of the ICM, but
there are some regions where the velocity difference between the two is about a
few hundred kilometer per second. The cluster galaxies show a hint of global
rotation at $R<5^\prime$ with $v_{\rm rot}=300{-}600\,\textrm{km s}^{-1}$, but
the ICM in the same region do not show such rotation. We apply a
friends-of-friends algorithm to the cluster galaxy sample at $R<60^\prime$ and
identify 32 group candidates, and examine the spatial correlation between the
galaxy groups and X-ray emission. This extensive survey in the central region
of A2199 provides an important basis for future studies of interplay among the
galaxies, the ICM and the dark matter in the cluster.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,113 | A trapped field of 13.4 T in a stack of HTS tapes with 30 μm substrate | Superconducting bulk (RE)Ba$_2$Cu$_3$O$_{7-x}$ materials (RE-rare earth
elements) have been successfully used to generate magnetic flux densities in
excess of 17 T. This work investigates an alternative approach by trapping flux
in stacks of second generation high temperature superconducting tape from
several manufacturers using field cooling and pulsed field magnetisation
techniques. Flux densities of up to 13.4 T were trapped by field cooling at ~5
K between two 12 mm square stacks, an improvement of 70% over previous value
achieved in an HTS tape stack. The trapped flux approaches the record values in
(RE)BCO bulks and reflects the rapid developments still being made in the HTS
tape performance.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,114 | Exact Simulation of the Extrema of Stable Processes | We exhibit an exact simulation algorithm for the supremum of a stable process
over a finite time interval using dominated coupling from the past (DCFTP). We
establish a novel perpetuity equation for the supremum (via the representation
of the concave majorants of Lévy processes) and apply it to construct a
Markov chain in the DCFTP algorithm. We prove that the number of steps taken
backwards in time before the coalescence is detected is finite.
| 0 | 0 | 0 | 1 | 0 | 0 |
17,115 | Nonparametric Bayesian estimation of a Hölder continuous diffusion coefficient | We consider a nonparametric Bayesian approach to estimate the diffusion
coefficient of a stochastic differential equation given discrete time
observations over a fixed time interval. As a prior on the diffusion
coefficient, we employ a histogram-type prior with piecewise constant
realisations on bins forming a partition of the time interval. Specifically,
these constants are realizations of independent inverse Gamma distributed
randoma variables. We justify our approach by deriving the rate at which the
corresponding posterior distribution asymptotically concentrates around the
data-generating diffusion coefficient. This posterior contraction rate turns
out to be optimal for estimation of a Hölder-continuous diffusion coefficient
with smoothness parameter $0<\lambda\leq 1.$ Our approach is straightforward to
implement, as the posterior distributions turn out to be inverse Gamma again,
and leads to good practical results in a wide range of simulation examples.
Finally, we apply our method on exchange rate data sets.
| 0 | 0 | 1 | 1 | 0 | 0 |
17,116 | Dirac State in a Centrosymmetric Superconductor alpha-PdBi2 | Topological superconductor (TSC) hosting Majorana fermions has been
established as a milestone that may shift our scientific trajectory from
research to applications in topological quantum computing. Recently,
superconducting Pd-Bi binaries have attracted great attention as a possible
medium for the TSC phase as a result of their large spin-orbit coupling
strength. Here, we report a systematic high-resolution angle-resolved
photoemission spectroscopy (ARPES) study on the normal state electronic
structure of superconducting alpha-PdBi2 (Tc = 1.7 K). Our results show the
presence of Dirac states at higher-binding energy with the location of the
Dirac point at 1.26 eV below the chemical potential at the zone center.
Furthermore, the ARPES data indicate multiple band crossings at the chemical
potential, consistent with the metallic behavior of alpha-PdBi2. Our detailed
experimental studies are complemented by first-principles calculations, which
reveal the presence of surface Rashba states residing in the vicinity of the
chemical potential. The obtained results provide an opportunity to investigate
the relationship between superconductivity and topology, as well as explore
pathways to possible future platforms for topological quantum computing.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,117 | Hölder and Lipschitz continuity of functions definable over Henselian rank one valued fields | Consider a Henselian rank one valued field $K$ of equicharacteristic zero
with the three-sorted language $\mathcal{L}$ of Denef--Pas. Let $f: A \to K$ be
a continuous $\mathcal{L}$-definable (with parameters) function on a closed
bounded subset $A \subset K^{n}$. The main purpose is to prove that then $f$ is
Hölder continuous with some exponent $s\geq 0$ and constant $c \geq 0$, a
fortiori, $f$ is uniformly continuous. Further, if $f$ is locally Lipschitz
continuous with a constant $c$, then $f$ is (globally) Lipschitz continuous
with possibly some larger constant $d$. Also stated are some problems
concerning continuous and Lipschitz continuous functions definable over
Henselian valued fields.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,118 | Bistability of Cavity Magnon Polaritons | We report the first observation of the magnon-polariton bistability in a
cavity magnonics system consisting of cavity photons strongly interacting with
the magnons in a small yttrium iron garnet (YIG) sphere. The bistable behaviors
are emerged as sharp frequency switchings of the cavity magnon-polaritons
(CMPs) and related to the transition between states with large and small number
of polaritons. In our experiment, we align, respectively, the [100] and [110]
crystallographic axes of the YIG sphere parallel to the static magnetic field
and find very different bistable behaviors (e.g., clockwise and
counter-clockwise hysteresis loops) in these two cases. The experimental
results are well fitted and explained as being due to the Kerr nonlinearity
with either positive or negative coefficient. Moreover, when the magnetic field
is tuned away from the anticrossing point of CMPs, we observe simultaneous
bistability of both magnons and cavity photons by applying a drive field on the
lower branch.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,119 | Errors and secret data in the Italian research assessment exercise. A comment to a reply | Italy adopted a performance-based system for funding universities that is
centered on the results of a national research assessment exercise, realized by
a governmental agency (ANVUR). ANVUR evaluated papers by using 'a dual system
of evaluation', that is by informed peer review or by bibliometrics. In view of
validating that system, ANVUR performed an experiment for estimating the
agreement between informed review and bibliometrics. Ancaiani et al. (2015)
presents the main results of the experiment. Baccini and De Nicolao (2017)
documented in a letter, among other critical issues, that the statistical
analysis was not realized on a random sample of articles. A reply to the letter
has been published by Research Evaluation (Benedetto et al. 2017). This note
highlights that in the reply there are (1) errors in data, (2) problems with
'representativeness' of the sample, (3) unverifiable claims about weights used
for calculating kappas, (4) undisclosed averaging procedures; (5) a statement
about 'same protocol in all areas' contradicted by official reports. Last but
not least: the data used by the authors continue to be undisclosed. A general
warning concludes: many recently published papers use data originating from
Italian research assessment exercise. These data are not accessible to the
scientific community and consequently these papers are not reproducible. They
can be hardly considered as containing sound evidence at least until authors or
ANVUR disclose the data necessary for replication.
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17,120 | Exploring Features for Predicting Policy Citations | In this study we performed an initial investigation and evaluation of
altmetrics and their relationship with public policy citation of research
papers. We examined methods for using altmetrics and other data to predict
whether a research paper is cited in public policy and applied receiver
operating characteristic curve on various feature groups in order to evaluate
their potential usefulness. From the methods we tested, classifying based on
tweet count provided the best results, achieving an area under the ROC curve of
0.91.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,121 | Recovery guarantees for compressed sensing with unknown errors | From a numerical analysis perspective, assessing the robustness of
l1-minimization is a fundamental issue in compressed sensing and sparse
regularization. Yet, the recovery guarantees available in the literature
usually depend on a priori estimates of the noise, which can be very hard to
obtain in practice, especially when the noise term also includes unknown
discrepancies between the finite model and data. In this work, we study the
performance of l1-minimization when these estimates are not available,
providing robust recovery guarantees for quadratically constrained basis
pursuit and random sampling in bounded orthonormal systems. Several
applications of this work are approximation of high-dimensional functions,
infinite-dimensional sparse regularization for inverse problems, and fast
algorithms for non-Cartesian Magnetic Resonance Imaging.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,122 | Synthetic Homology in Homotopy Type Theory | This paper defines homology in homotopy type theory, in the process stable
homotopy groups are also defined. Previous research in synthetic homotopy
theory is relied on, in particular the definition of cohomology. This work lays
the foundation for a computer checked construction of homology.
| 1 | 0 | 1 | 0 | 0 | 0 |
17,123 | Spatial Models of Vector-Host Epidemics with Directed Movement of Vectors Over Long Distances | We investigate a time-dependent spatial vector-host epidemic model with
non-coincident domains for the vector and host populations. The host population
resides in small non-overlapping sub-regions, while the vector population
resides throughout a much larger region. The dynamics of the populations are
modeled by a reaction-diffusion-advection compartmental system of partial
differential equations. The disease is transmitted through vector and host
populations in criss-cross fashion. We establish global well-posedness and
uniform a prior bounds as well as the long-term behavior. The model is applied
to simulate the outbreak of bluetongue disease in sheep transmitted by midges
infected with bluetongue virus. We show that the long-range directed movement
of the midge population, due to wind-aided movement, enhances the transmission
of the disease to sheep in distant sites.
| 0 | 0 | 0 | 0 | 1 | 0 |
17,124 | Complex and Quaternionic Principal Component Pursuit and Its Application to Audio Separation | Recently, the principal component pursuit has received increasing attention
in signal processing research ranging from source separation to video
surveillance. So far, all existing formulations are real-valued and lack the
concept of phase, which is inherent in inputs such as complex spectrograms or
color images. Thus, in this letter, we extend principal component pursuit to
the complex and quaternionic cases to account for the missing phase
information. Specifically, we present both complex and quaternionic proximity
operators for the $\ell_1$- and trace-norm regularizers. These operators can be
used in conjunction with proximal minimization methods such as the inexact
augmented Lagrange multiplier algorithm. The new algorithms are then applied to
the singing voice separation problem, which aims to separate the singing voice
from the instrumental accompaniment. Results on the iKala and MSD100 datasets
confirmed the usefulness of phase information in principal component pursuit.
| 0 | 0 | 0 | 1 | 0 | 0 |
17,125 | Light axion-like dark matter must be present during inflation | Axion-like particles (ALPs) might constitute the totality of the cold dark
matter (CDM) observed. The parameter space of ALPs depends on the mass of the
particle $m$ and on the energy scale of inflation $H_I$ , the latter being
bound by the non-detection of primordial gravitational waves. We show that the
bound on HI implies the existence of a mass scale $m_\chi = 10 {\rm \,neV}
÷ 0.5 {\rm \,peV}$, depending on the ALP susceptibility $\chi$, such that
the energy density of ALPs of mass smaller than $m_\chi$ is too low to explain
the present CDM budget, if the ALP field has originated after the end of
inflation. This bound affects Ultra-Light Axions (ULAs), which have recently
regained popularity as CDM candidates. Light ($m < m_\chi$) ALPs can then be
CDM candidates only if the ALP field has already originated during the
inflationary period, in which case the parameter space is constrained by the
non-detection of axion isocurvature fluctuations. We comment on the effects on
these bounds from additional physics beyond the Standard Model, besides ALPs.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,126 | Boolean function analysis meets stochastic optimization: An approximation scheme for stochastic knapsack | The stochastic knapsack problem is the stochastic variant of the classical
knapsack problem in which the algorithm designer is given a a knapsack with a
given capacity and a collection of items where each item is associated with a
profit and a probability distribution on its size. The goal is to select a
subset of items with maximum profit and violate the capacity constraint with
probability at most $p$ (referred to as the overflow probability). While
several approximation algorithms have been developed for this problem, most of
these algorithms relax the capacity constraint of the knapsack. In this paper,
we design efficient approximation schemes for this problem without relaxing the
capacity constraint.
(i) Our first result is in the case when item sizes are Bernoulli random
variables. In this case, we design a (nearly) fully polynomial time
approximation scheme (FPTAS) which only relaxes the overflow probability. (ii)
Our second result generalizes the first result to the case when all the item
sizes are supported on a (common) set of constant size. (iii) Our third result
is in the case when item sizes are so-called "hypercontractive" random
variables i.e., random variables whose second and fourth moments are within
constant factors of each other. In other words, the kurtosis of the random
variable is upper bounded by a constant.
Crucially, all of our algorithms meet the capacity constraint exactly, a
result which was previously known only when the item sizes were Poisson or
Gaussian random variables. Our results rely on new connections between Boolean
function analysis and stochastic optimization. We believe that these ideas and
techniques may prove to be useful in other stochastic optimization problems as
well.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,127 | Nonparanormal Information Estimation | We study the problem of using i.i.d. samples from an unknown multivariate
probability distribution $p$ to estimate the mutual information of $p$. This
problem has recently received attention in two settings: (1) where $p$ is
assumed to be Gaussian and (2) where $p$ is assumed only to lie in a large
nonparametric smoothness class. Estimators proposed for the Gaussian case
converge in high dimensions when the Gaussian assumption holds, but are
brittle, failing dramatically when $p$ is not Gaussian. Estimators proposed for
the nonparametric case fail to converge with realistic sample sizes except in
very low dimensions. As a result, there is a lack of robust mutual information
estimators for many realistic data. To address this, we propose estimators for
mutual information when $p$ is assumed to be a nonparanormal (a.k.a., Gaussian
copula) model, a semiparametric compromise between Gaussian and nonparametric
extremes. Using theoretical bounds and experiments, we show these estimators
strike a practical balance between robustness and scaling with dimensionality.
| 1 | 0 | 1 | 1 | 0 | 0 |
17,128 | Controlling a population | We introduce a new setting where a population of agents, each modelled by a
finite-state system, are controlled uniformly: the controller applies the same
action to every agent. The framework is largely inspired by the control of a
biological system, namely a population of yeasts, where the controller may only
change the environment common to all cells. We study a synchronisation problem
for such populations: no matter how individual agents react to the actions of
the controller, the controller aims at driving all agents synchronously to a
target state. The agents are naturally represented by a non-deterministic
finite state automaton (NFA), the same for every agent, and the whole system is
encoded as a 2-player game. The first player (Controller) chooses actions, and
the second player (Agents) resolves non-determinism for each agent. The game
with m agents is called the m -population game. This gives rise to a
parameterized control problem (where control refers to 2 player games), namely
the population control problem: can Controller control the m-population game
for all m in N whatever Agents does?
| 1 | 0 | 0 | 0 | 0 | 0 |
17,129 | Finite scale local Lyapunov exponents distribution in fully developed homogeneous isotropic turbulence | The present work analyzes the distribution function of the finite scale local
Lyapunov exponent of a pair fluid particles trajectories in fully developed
incompressible homogeneous isotropic turbulence. According to the hypothesis of
fully developed chaos, this PDF is reasonably estimated by maximizing the
entropy associated to such distribution, resulting to be an uniform
distribution function in a proper interval of variation of the local Lyapunov
exponents. From this PDF, we determine the relationship between the average and
maximum Lyapunov exponents and the longitudinal velocity correlation function.
This link, which leads to the closure of von Kàrmàn--Howarth and Corrsin
equations, agrees with the relation obtained in the previous work, supporting
the proposed PDF calculation, at least for the purposes of the energy cascade
effect estimation. Furthermore, through the property that the Lyapunov vectors
tend to align to the direction of the maximum growth rate of trajectories
distance, we obtain the link between maximum and average Lyapunov exponents in
line with the previous result.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,130 | Improved Power Decoding of One-Point Hermitian Codes | We propose a new partial decoding algorithm for one-point Hermitian codes
that can decode up to the same number of errors as the Guruswami--Sudan
decoder. Simulations suggest that it has a similar failure probability as the
latter one. The algorithm is based on a recent generalization of the power
decoding algorithm for Reed--Solomon codes and does not require an expensive
root-finding step. In addition, it promises improvements for decoding
interleaved Hermitian codes.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,131 | Finite numbers of initial ideals in non-Noetherian polynomial rings | In this article, we generalize the well-known result that ideals of
Noetherian polynomial rings have only finitely many initial ideals to the
situation of ascending ideal chains in non-Noetherian polynomial rings. More
precisely, we study ideal chains in the polynomial ring $R=K[x_{i,j}\,|\,1\leq
i\leq c,j\in N]$ that are invariant under the action of the monoid $Inc(N)$ of
strictly increasing functions on $N$, which acts on $R$ by shifting the second
variable index. We show that for every such ideal chain, the number of initial
ideal chains with respect to term orders on $R$ that are compatible with the
action of $Inc(N)$ is finite. As a consequence of this, we will see that
$Inc(N)$-invariant ideals of $R$ have only finitely many initial ideals with
respect to $Inc(N)$-compatible term orders. The article also addresses the
question of how many such term orders exist. We give a complete list of the
$Inc(N)$-compatible term orders for the case $c=1$ and show that there are
infinitely many for $c >1$. This answers a question by Hillar, Kroner, Leykin.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,132 | The Diederich-Fornaess Index and Good Vector Fields | We consider the relationship between two sufficient conditions for regularity
of the Bergman Projection on smooth, bounded, pseudoconvex domains. We show
that if the set of infinite type points is reasonably well-behaved, then the
existence of a family of good vector fields in the sense of Boas and Straube
implies that the Diederich-Fornaess Index of the domain is equal to one.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,133 | Complete Minors of Self-Complementary Graphs | We show that any self-complementary graph with $n$ vertices contains a
$K_{\lfloor \frac{n+1}{2}\rfloor}$ minor. We derive topological properties of
self-complementary graphs.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,134 | Statistical estimation of the Oscillating Brownian Motion | We study the asymptotic behavior of estimators of a two-valued, discontinuous
diffusion coefficient in a Stochastic Differential Equation, called an
Oscillating Brownian Motion. Using the relation of the latter process with the
Skew Brownian Motion, we propose two natural consistent estimators, which are
variants of the integrated volatility estimator and take the occupation times
into account. We show the stable convergence of the renormalized errors'
estimations toward some Gaussian mixture, possibly corrected by a term that
depends on the local time. These limits stem from the lack of ergodicity as
well as the behavior of the local time at zero of the process. We test both
estimators on simulated processes, finding a complete agreement with the
theoretical predictions.
| 0 | 0 | 1 | 1 | 0 | 0 |
17,135 | Competing Ferromagnetic and Anti-Ferromagnetic interactions in Iron Nitride $ζ$-Fe$_2$N | The paper discusses the magnetic state of zeta phase of iron nitride viz.
$\zeta$-Fe$_2$N on the basis of spin polarized first principles electronic
structure calculations together with a review of already published data.
Results of our first principles study suggest that the ground state of
$\zeta$-Fe$_2$N is ferromagnetic (FM) with a magnetic moment of 1.528
$\mu_\text{B}$ on the Fe site. The FM ground state is lower than the
anti-ferromagnetic (AFM) state by 8.44 meV and non-magnetic(NM) state by 191
meV per formula unit. These results are important in view of reports which
claim that $\zeta$-Fe$_2$N undergoes an AFM transition below 10K and others
which do not observe any magnetic transition up to 4.2K. We argue that the
experimental results of AFM transition below 10K are inconclusive and we
propose the presence of competing FM and AFM superexchange interactions between
Fe sites mediated by nitrogen atoms, which are consistent with
Goodenough-Kanamori-Anderson rules. We find that the anti-ferromagnetically
coupled Fe sites are outnumbered by ferromagnetically coupled Fe sites leading
to a stable FM ground state. A Stoner analysis of the results also supports our
claim of a FM ground state.
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17,136 | A cautionary tale: limitations of a brightness-based spectroscopic approach to chromatic exoplanet radii | Determining wavelength-dependent exoplanet radii measurements is an excellent
way to probe the composition of exoplanet atmospheres. In light of this, Borsa
et al. (2016) sought to develop a technique to obtain such measurements by
comparing ground-based transmission spectra to the expected brightness
variations during an exoplanet transit. However, we demonstrate herein that
this is not possible due to the transit light curve normalisation necessary to
remove the effects of the Earth's atmosphere on the ground-based observations.
This is because the recoverable exoplanet radius is set by the planet-to-star
radius ratio within the transit light curve; we demonstrate this both
analytically and with simulated planet transits, as well as through a
reanalysis of the HD 189733b data.
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17,137 | Generating Memorable Mnemonic Encodings of Numbers | The major system is a mnemonic system that can be used to memorize sequences
of numbers. In this work, we present a method to automatically generate
sentences that encode a given number. We propose several encoding models and
compare the most promising ones in a password memorability study. The results
of the study show that a model combining part-of-speech sentence templates with
an $n$-gram language model produces the most memorable password
representations.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,138 | De-excitation spectroscopy of strongly interacting Rydberg gases | We present experimental results on the controlled de-excitation of Rydberg
states in a cold gas of Rb atoms. The effect of the van der Waals interactions
between the Rydberg atoms is clearly seen in the de-excitation spectrum and
dynamics. Our observations are confirmed by numerical simulations. In
particular, for off-resonant (facilitated) excitation we find that the
de-excitation spectrum reflects the spatial arrangement of the atoms in the
quasi one-dimensional geometry of our experiment. We discuss future
applications of this technique and implications for detection and controlled
dissipation schemes.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,139 | Hyperplane Clustering Via Dual Principal Component Pursuit | We extend the theoretical analysis of a recently proposed single subspace
learning algorithm, called Dual Principal Component Pursuit (DPCP), to the case
where the data are drawn from of a union of hyperplanes. To gain insight into
the properties of the $\ell_1$ non-convex problem associated with DPCP, we
develop a geometric analysis of a closely related continuous optimization
problem. Then transferring this analysis to the discrete problem, our results
state that as long as the hyperplanes are sufficiently separated, the dominant
hyperplane is sufficiently dominant and the points are uniformly distributed
inside the associated hyperplanes, then the non-convex DPCP problem has a
unique global solution, equal to the normal vector of the dominant hyperplane.
This suggests the correctness of a sequential hyperplane learning algorithm
based on DPCP. A thorough experimental evaluation reveals that hyperplane
learning schemes based on DPCP dramatically improve over the state-of-the-art
methods for the case of synthetic data, while are competitive to the
state-of-the-art in the case of 3D plane clustering for Kinect data.
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17,140 | Utilizing Domain Knowledge in End-to-End Audio Processing | End-to-end neural network based approaches to audio modelling are generally
outperformed by models trained on high-level data representations. In this
paper we present preliminary work that shows the feasibility of training the
first layers of a deep convolutional neural network (CNN) model to learn the
commonly-used log-scaled mel-spectrogram transformation. Secondly, we
demonstrate that upon initializing the first layers of an end-to-end CNN
classifier with the learned transformation, convergence and performance on the
ESC-50 environmental sound classification dataset are similar to a CNN-based
model trained on the highly pre-processed log-scaled mel-spectrogram features.
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17,141 | Testing Microfluidic Fully Programmable Valve Arrays (FPVAs) | Fully Programmable Valve Array (FPVA) has emerged as a new architecture for
the next-generation flow-based microfluidic biochips. This 2D-array consists of
regularly-arranged valves, which can be dynamically configured by users to
realize microfluidic devices of different shapes and sizes as well as
interconnections. Additionally, the regularity of the underlying structure
renders FPVAs easier to integrate on a tiny chip. However, these arrays may
suffer from various manufacturing defects such as blockage and leakage in
control and flow channels. Unfortunately, no efficient method is yet known for
testing such a general-purpose architecture. In this paper, we present a novel
formulation using the concept of flow paths and cut-sets, and describe an
ILP-based hierarchical strategy for generating compact test sets that can
detect multiple faults in FPVAs. Simulation results demonstrate the efficacy of
the proposed method in detecting manufacturing faults with only a small number
of test vectors.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,142 | Fundamental groups, slalom curves and extremal length | We define the extremal length of elements of the fundamental group of the
twice punctured complex plane and give upper and lower bounds for this
invariant. The bounds differ by a multiplicative constant. The main motivation
comes from $3$-braid invariants and their application.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,143 | Topology and stability of the Kondo phase in quark matter | We investigate properties of the ground state of a light quark matter with
heavy quark impurities. This system exhibits the "QCD Kondo effect" where the
interaction strength between a light quark near the Fermi surface and a heavy
quark increases with decreasing energy of the light quark towards the Fermi
energy, and diverges at some scale near the Fermi energy, called the Kondo
scale. Around and below the Kondo scale, we must treat the dynamics
nonperturbatively. As a typical nonperturbative method to treat the strong
coupling regime, we adopt a mean-field approach where we introduce a
condensate, the Kondo condensate, representing a mixing between a light quark
and a heavy quark, and determine the ground state in the presence of the Kondo
condensate. We show that the ground state is a topologically non-trivial state
and the heavy quark spin forms the hedgehog configuration in the momentum
space. We can define the Berry phase for the ground-state wavefunction in the
momentum space which is associated with a monopole at the position of a heavy
quark. We also investigate fluctuations around the mean field in the
random-phase approximation, and show the existence of (exciton-like) collective
excitations made of a hole $h$ of a light quark and a heavy quark $Q$.
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17,144 | Second order nonlinear gyrokinetic theory : From the particle to the gyrocenter | A gyrokinetic reduction is based on a specific ordering of the different
small parameters characterizing the background magnetic field and the
fluctuating electromagnetic fields. In this tutorial, we consider the following
ordering of the small parameters: $\epsilon\_B=\epsilon\_\delta^2$ where
$\epsilon\_B$ is the small parameter associated with spatial inhomogeneities of
the background magnetic field and $\epsilon\_\delta$ characterizes the small
amplitude of the fluctuating fields. In particular, we do not make any
assumption on the amplitude of the background magnetic field. Given this choice
of ordering, we describe a self-contained and systematic derivation which is
particularly well suited for the gyrokinetic reduction, following a two-step
procedure. We follow the approach developed in [Sugama, Physics of Plasmas 7,
466 (2000)]:In a first step, using a translation in velocity, we embed the
transformation performed on the symplectic part of the gyrocentre reduction in
the guiding-centre one. In a second step, using a canonical Lie transform, we
eliminate the gyroangle dependence from the Hamiltonian. As a consequence, we
explicitly derive the fully electromagnetic gyrokinetic equations at the second
order in $\epsilon\_\delta$.
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17,145 | On the Classification and Algorithmic Analysis of Carmichael Numbers | In this paper, we study the properties of Carmichael numbers, false positives
to several primality tests. We provide a classification for Carmichael numbers
with a proportion of Fermat witnesses of less than 50%, based on if the
smallest prime factor is greater than a determined lower bound. In addition, we
conduct a Monte Carlo simulation as part of a probabilistic algorithm to detect
if a given composite number is Carmichael. We modify this highly accurate
algorithm with a deterministic primality test to create a novel, more efficient
algorithm that differentiates between Carmichael numbers and prime numbers.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,146 | Phase reduction and synchronization of a network of coupled dynamical elements exhibiting collective oscillations | A general phase reduction method for a network of coupled dynamical elements
exhibiting collective oscillations, which is applicable to arbitrary networks
of heterogeneous dynamical elements, is developed. A set of coupled adjoint
equations for phase sensitivity functions, which characterize phase response of
the collective oscillation to small perturbations applied to individual
elements, is derived. Using the phase sensitivity functions, collective
oscillation of the network under weak perturbation can be described
approximately by a one-dimensional phase equation. As an example, mutual
synchronization between a pair of collectively oscillating networks of
excitable and oscillatory FitzHugh-Nagumo elements with random coupling is
studied.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,147 | Analysis of the Impact of Negative Sampling on Link Prediction in Knowledge Graphs | Knowledge graphs are large, useful, but incomplete knowledge repositories.
They encode knowledge through entities and relations which define each other
through the connective structure of the graph. This has inspired methods for
the joint embedding of entities and relations in continuous low-dimensional
vector spaces, that can be used to induce new edges in the graph, i.e., link
prediction in knowledge graphs. Learning these representations relies on
contrasting positive instances with negative ones. Knowledge graphs include
only positive relation instances, leaving the door open for a variety of
methods for selecting negative examples. In this paper we present an empirical
study on the impact of negative sampling on the learned embeddings, assessed
through the task of link prediction. We use state-of-the-art knowledge graph
embeddings -- \rescal , TransE, DistMult and ComplEX -- and evaluate on
benchmark datasets -- FB15k and WN18. We compare well known methods for
negative sampling and additionally propose embedding based sampling methods. We
note a marked difference in the impact of these sampling methods on the two
datasets, with the "traditional" corrupting positives method leading to best
results on WN18, while embedding based methods benefiting the task on FB15k.
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17,148 | Reverse Curriculum Generation for Reinforcement Learning | Many relevant tasks require an agent to reach a certain state, or to
manipulate objects into a desired configuration. For example, we might want a
robot to align and assemble a gear onto an axle or insert and turn a key in a
lock. These goal-oriented tasks present a considerable challenge for
reinforcement learning, since their natural reward function is sparse and
prohibitive amounts of exploration are required to reach the goal and receive
some learning signal. Past approaches tackle these problems by exploiting
expert demonstrations or by manually designing a task-specific reward shaping
function to guide the learning agent. Instead, we propose a method to learn
these tasks without requiring any prior knowledge other than obtaining a single
state in which the task is achieved. The robot is trained in reverse, gradually
learning to reach the goal from a set of start states increasingly far from the
goal. Our method automatically generates a curriculum of start states that
adapts to the agent's performance, leading to efficient training on
goal-oriented tasks. We demonstrate our approach on difficult simulated
navigation and fine-grained manipulation problems, not solvable by
state-of-the-art reinforcement learning methods.
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17,149 | Mutually touching infinite cylinders in the 3D world of lines | Recently we gave arguments that only two unique topologically different
configurations of 7 equal all mutually touching round cylinders (the
configurations being mirror reflections of each other) are possible in 3D,
although a whole world of configurations is possible already for round
cylinders of arbitrary radii. It was found that as many as 9 round cylinders
(all mutually touching) are possible in 3D while the upper bound for arbitrary
cylinders was estimated to be not more than 14 under plausible arguments. Now
by using the chirality and Ring matrices that we introduced earlier for the
topological classification of line configurations, we have given arguments that
the maximal number of mutually touching straight infinite cylinders of
arbitrary cross-section (provided that its boundary is a smooth curve) in 3D
cannot exceed 10. We generated numerically several configurations of 10
cylinders, restricting ourselves with elliptic cylinders. Configurations of 8
and 9 equal elliptic cylinders (all in mutually touching) are generated
numerically as well. A possibility and restriction of continuous
transformations from elliptic into round cylinder configurations are discussed.
Some curious results concerning the properties of the chirality matrix (which
coincides with Seidel's adjacency matrix important for the Graph theory) are
presented.
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17,150 | Introduction to Formal Concept Analysis and Its Applications in Information Retrieval and Related Fields | This paper is a tutorial on Formal Concept Analysis (FCA) and its
applications. FCA is an applied branch of Lattice Theory, a mathematical
discipline which enables formalisation of concepts as basic units of human
thinking and analysing data in the object-attribute form. Originated in early
80s, during the last three decades, it became a popular human-centred tool for
knowledge representation and data analysis with numerous applications. Since
the tutorial was specially prepared for RuSSIR 2014, the covered FCA topics
include Information Retrieval with a focus on visualisation aspects, Machine
Learning, Data Mining and Knowledge Discovery, Text Mining and several others.
| 1 | 0 | 0 | 1 | 0 | 0 |
17,151 | Fully stripped? The dynamics of dark and luminous matter in the massive cluster collision MACSJ0553.4$-$3342 | We present the results of a multiwavelength investigation of the very X-ray
luminous galaxy cluster MACSJ0553.4-3342 ($z = 0.4270$; hereafter MACSJ0553).
Combining high-resolution data obtained with the Hubble Space Telescope and the
Chandra X-ray Observatory with ground-based galaxy spectroscopy, our analysis
establishes the system unambiguously as a binary, post-collision merger of
massive clusters. Key characteristics include perfect alignment of luminous and
dark matter for one component, a separation of almost 650 kpc (in projection)
between the dark-matter peak of the other subcluster and the second X-ray peak,
extremely hot gas (k$T > 15$ keV) at either end of the merger axis, a potential
cold front in the east, an unusually low gas mass fraction of approximately
0.075 for the western component, a velocity dispersion of $1490_{-130}^{+104}$
km s$^{-1}$, and no indication of significant substructure along the line of
sight. We propose that the MACSJ0553 merger proceeds not in the plane of the
sky, but at a large inclination angle, is observed very close to turnaround,
and that the eastern X-ray peak is the cool core of the slightly less massive
western component that was fully stripped and captured by the eastern
subcluster during the collision. If correct, this hypothesis would make
MACSJ0553 a superb target for a competitive study of ram-pressure stripping and
the collisional behaviour of luminous and dark matter during cluster formation.
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17,152 | When intuition fails in assessing conditional risks: the example of the frog riddle | Recently, the educational initiative TED-Ed has published a popular brain
teaser coined the 'frog riddle', which illustrates non-intuitive implications
of conditional probabilities. In its intended form, the frog riddle is a
reformulation of the classic boy-girl paradox. However, the authors alter the
narrative of the riddle in a form, that subtly changes the way information is
conveyed. The presented solution, unfortunately, does not take this point into
full account, and as a consequence, lacks consistency in the sense that
different parts of the problem are treated on unequal footing. We here review,
how the mechanism of receiving information matters, and why this is exactly the
reason that such kind of problems challenge intuitive thinking. Subsequently,
we present a generalized solution, that accounts for the above difficulties,
and preserves full logical consistency. Eventually, the relation to the
boy-girl paradox is discussed.
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17,153 | Tuning parameter selection rules for nuclear norm regularized multivariate linear regression | We consider the tuning parameter selection rules for nuclear norm regularized
multivariate linear regression (NMLR) in high-dimensional setting.
High-dimensional multivariate linear regression is widely used in statistics
and machine learning, and regularization technique is commonly applied to deal
with the special structures in high-dimensional data. As we know, how to select
the tuning parameter is an essential issue for regularization approach and it
directly affects the model estimation performance. To the best of our
knowledge, there are no rules about the tuning parameter selection for NMLR
from the point of view of optimization. In order to establish such rules, we
study the duality theory of NMLR. Then, we claim the choice of tuning parameter
for NMLR is based on the sample data and the solution of NMLR dual problem,
which is a projection on a nonempty, closed and convex set. Moreover, based on
the (firm) nonexpansiveness and the idempotence of the projection operator, we
build four tuning parameter selection rules PSR, PSRi, PSRfn and PSR+.
Furthermore, we give a sequence of tuning parameters and the corresponding
intervals for every rule, which states that the rank of the estimation
coefficient matrix is no more than a fixed number for the tuning parameter in
the given interval. The relationships between these rules are also discussed
and PSR+ is the most efficient one to select the tuning parameter. Finally, the
numerical results are reported on simulation and real data, which show that
these four tuning parameter selection rules are valuable.
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17,154 | Understanding the evolution of multimedia content in the Internet through BitTorrent glasses | Today's Internet traffic is mostly dominated by multimedia content and the
prediction is that this trend will intensify in the future. Therefore, main
Internet players, such as ISPs, content delivery platforms (e.g. Youtube,
Bitorrent, Netflix, etc) or CDN operators, need to understand the evolution of
multimedia content availability and popularity in order to adapt their
infrastructures and resources to satisfy clients requirements while they
minimize their costs. This paper presents a thorough analysis on the evolution
of multimedia content available in BitTorrent. Specifically, we analyze the
evolution of four relevant metrics across different content categories: content
availability, content popularity, content size and user's feedback. To this end
we leverage a large-scale dataset formed by 4 snapshots collected from the most
popular BitTorrent portal, namely The Pirate Bay, between Nov. 2009 and Feb.
2012. Overall our dataset is formed by more than 160k content that attracted
more than 185M of download sessions.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,155 | The weak rate of convergence for the Euler-Maruyama approximation of one-dimensional stochastic differential equations involving the local times of the unknown process | In this paper, we consider the weak convergence of the Euler-Maruyama
approximation for one dimensional stochastic differential equations involving
the local times of the unknown process. We use a transformation in order to
remove the local time from the stochastic differential equations and we provide
the approximation of Euler-maruyama for the stochastic differential equations
without local time. After that, we conclude the approximation of Euler-maruyama
for one dimensional stochastic differential equations involving the local times
of the unknown process , and we provide the rate of weak convergence for any
function G in a certain class.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,156 | Study of deteriorating semiopaque turquoise lead-potassium glass beads at different stages of corrosion using micro-FTIR spectroscopy | Nowadays, a problem of historical beadworks conservation in museum
collections is actual more than ever because of fatal corrosion of the 19th
century glass beads. Vibrational spectroscopy is a powerful method for
investigation of glass, namely, of correlation of the structure-chemical
composition. Therefore, Fourier-transform infrared spectroscopy was used for
examination of degradation processes in cloudy turquoise glass beads, which in
contrast to other color ones deteriorate especially strongly. Micro-X-ray
fluorescence spectrometry of samples has shown that lead-potassium glass
PbO-K$_2$O-SiO$_2$ with small amount of Cu and Sb was used for manufacture of
cloudy turquoise beads. Fourier-transform infrared spectroscopy study of the
beads at different stages of glass corrosion was carried out in the range from
200 to 4000 cm$^{-1}$ in the attenuated total reflection mode. In all the
spectra, we have observed shifts of two major absorption bands to low-frequency
range (~1000 and ~775 cm$^{-1}$) compared to ones typical for amorphous SiO2
(~1100 and 800 cm$^{-1}$, respectively). Such an effect is connected with
Pb$^{2+}$ and K$^+$ appending to the glass network. The presence of a weak band
at ~1630 cm$^{-1}$ in all the spectra is attributed to the adsorption of
H$_2$O. After annealing of the beads, the band disappeared completely in less
deteriorated samples and became significantly weaker in more destroyed ones.
Based on that we conclude that there is adsorbed molecular water on the beads.
However, products of corrosion (e.g., alkali in the form of white crystals or
droplets of liquid alkali) were not observed on the glass surface. We have also
observed glass depolymerisation in the strongly degraded beads, which is
exhibited in domination of the band peaked at ~1000 cm$^{-1}$.
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17,157 | Stratified surgery and K-theory invariants of the signature operator | In work of Higson-Roe the fundamental role of the signature as a homotopy and
bordism invariant for oriented manifolds is made manifest in how it and related
secondary invariants define a natural transformation between the
(Browder-Novikov-Sullivan-Wall) surgery exact sequence and a long exact
sequence of C*-algebra K-theory groups.
In recent years the (higher) signature invariants have been extended from
closed oriented manifolds to a class of stratified spaces known as L-spaces or
Cheeger spaces. In this paper we show that secondary invariants, such as the
rho-class, also extend from closed manifolds to Cheeger spaces. We revisit a
surgery exact sequence for stratified spaces originally introduced by
Browder-Quinn and obtain a natural transformation analogous to that of
Higson-Roe. We also discuss geometric applications.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,158 | Weighted Tensor Decomposition for Learning Latent Variables with Partial Data | Tensor decomposition methods are popular tools for learning latent variables
given only lower-order moments of the data. However, the standard assumption is
that we have sufficient data to estimate these moments to high accuracy. In
this work, we consider the case in which certain dimensions of the data are not
always observed---common in applied settings, where not all measurements may be
taken for all observations---resulting in moment estimates of varying quality.
We derive a weighted tensor decomposition approach that is computationally as
efficient as the non-weighted approach, and demonstrate that it outperforms
methods that do not appropriately leverage these less-observed dimensions.
| 0 | 0 | 0 | 1 | 0 | 0 |
17,159 | Sparse Bounds for Discrete Quadratic Phase Hilbert Transform | Consider the discrete quadratic phase Hilbert Transform acting on $\ell^{2}$
finitely supported functions $$ H^{\alpha} f(n) : = \sum_{m \neq 0} \frac{e^{2
\pi i\alpha m^2} f(n - m)}{m}. $$ We prove that, uniformly in $\alpha \in
\mathbb{T}$, there is a sparse bound for the bilinear form $\langle H^{\alpha}
f , g \rangle$. The sparse bound implies several mapping properties such as
weighted inequalities in an intersection of Muckenhoupt and reverse Hölder
classes.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,160 | Fast Distributed Approximation for TAP and 2-Edge-Connectivity | The tree augmentation problem (TAP) is a fundamental network design problem,
in which the input is a graph $G$ and a spanning tree $T$ for it, and the goal
is to augment $T$ with a minimum set of edges $Aug$ from $G$, such that $T \cup
Aug$ is 2-edge-connected.
TAP has been widely studied in the sequential setting. The best known
approximation ratio of 2 for the weighted case dates back to the work of
Frederickson and JáJá, SICOMP 1981. Recently, a 3/2-approximation was
given for the unweighted case by Kortsarz and Nutov, TALG 2016, and recent
breakthroughs by Adjiashvili, SODA 2017, and by Fiorini et al., 2017, give
approximations better than 2 for bounded weights.
In this paper, we provide the first fast distributed approximations for TAP.
We present a distributed $2$-approximation for weighted TAP which completes in
$O(h)$ rounds, where $h$ is the height of $T$. When $h$ is large, we show a
much faster 4-approximation algorithm for the unweighted case, completing in
$O(D+\sqrt{n}\log^*{n})$ rounds, where $n$ is the number of vertices and $D$ is
the diameter of $G$.
Immediate consequences of our results are an $O(D)$-round 2-approximation
algorithm for the minimum size 2-edge-connected spanning subgraph, which
significantly improves upon the running time of previous approximation
algorithms, and an $O(h_{MST}+\sqrt{n}\log^{*}{n})$-round 3-approximation
algorithm for the weighted case, where $h_{MST}$ is the height of the MST of
the graph. Additional applications are algorithms for verifying
2-edge-connectivity and for augmenting the connectivity of any connected
spanning subgraph to 2.
Finally, we complement our study with proving lower bounds for distributed
approximations of TAP.
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17,161 | Generative Adversarial Source Separation | Generative source separation methods such as non-negative matrix
factorization (NMF) or auto-encoders, rely on the assumption of an output
probability density. Generative Adversarial Networks (GANs) can learn data
distributions without needing a parametric assumption on the output density. We
show on a speech source separation experiment that, a multi-layer perceptron
trained with a Wasserstein-GAN formulation outperforms NMF, auto-encoders
trained with maximum likelihood, and variational auto-encoders in terms of
source to distortion ratio.
| 1 | 0 | 0 | 1 | 0 | 0 |
17,162 | Bootstrapping Generalization Error Bounds for Time Series | We consider the problem of finding confidence intervals for the risk of
forecasting the future of a stationary, ergodic stochastic process, using a
model estimated from the past of the process. We show that a bootstrap
procedure provides valid confidence intervals for the risk, when the data
source is sufficiently mixing, and the loss function and the estimator are
suitably smooth. Autoregressive (AR(d)) models estimated by least squares obey
the necessary regularity conditions, even when mis-specified, and simulations
show that the finite- sample coverage of our bounds quickly converges to the
theoretical, asymptotic level. As an intermediate step, we derive sufficient
conditions for asymptotic independence between empirical distribution functions
formed by splitting a realization of a stochastic process, of independent
interest.
| 0 | 0 | 1 | 1 | 0 | 0 |
17,163 | Sign reversal of magnetoresistance and p to n transition in Ni doped ZnO thin film | We report the magnetoresistance and nonlinear Hall effect studies over a wide
temperature range in pulsed laser deposited Ni0.07Zn0.93O thin film. Negative
and positive contributions to magnetoresistance at high and low temperatures
have been successfully modeled by the localized magnetic moment and two band
conduction process involving heavy and light hole subbands, respectively.
Nonlinearity in the Hall resistance also agrees well with the two channel
conduction model. A negative Hall voltage has been found for T $\gte 50 K$,
implying a dominant conduction mainly by electrons whereas positive Hall
voltage for T less than 50 K shows hole dominated conduction in this material.
Crossover in the sign of magnetoresistance from negative to positive reveals
the spin polarization of the charge carriers and hence the applicability of Ni
doped ZnO thin film for spintronic applications.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,164 | Proceedings of the Third Workshop on Formal Integrated Development Environment | This volume contains the proceedings of F-IDE 2016, the third international
workshop on Formal Integrated Development Environment, which was held as an FM
2016 satellite event, on November 8, 2016, in Limassol (Cyprus). High levels of
safety, security and also privacy standards require the use of formal methods
to specify and develop compliant software (sub)systems. Any standard comes with
an assessment process, which requires a complete documentation of the
application in order to ease the justification of design choices and the review
of code and proofs. Thus tools are needed for handling specifications, program
constructs and verification artifacts. The aim of the F-IDE workshop is to
provide a forum for presenting and discussing research efforts as well as
experience returns on design, development and usage of formal IDE aiming at
making formal methods "easier" for both specialists and non-specialists.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,165 | A Useful Motif for Flexible Task Learning in an Embodied Two-Dimensional Visual Environment | Animals (especially humans) have an amazing ability to learn new tasks
quickly, and switch between them flexibly. How brains support this ability is
largely unknown, both neuroscientifically and algorithmically. One reasonable
supposition is that modules drawing on an underlying general-purpose sensory
representation are dynamically allocated on a per-task basis. Recent results
from neuroscience and artificial intelligence suggest the role of the general
purpose visual representation may be played by a deep convolutional neural
network, and give some clues how task modules based on such a representation
might be discovered and constructed. In this work, we investigate module
architectures in an embodied two-dimensional touchscreen environment, in which
an agent's learning must occur via interactions with an environment that emits
images and rewards, and accepts touches as input. This environment is designed
to capture the physical structure of the task environments that are commonly
deployed in visual neuroscience and psychophysics. We show that in this
context, very simple changes in the nonlinear activations used by such a module
can significantly influence how fast it is at learning visual tasks and how
suitable it is for switching to new tasks.
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17,166 | 3D Move to See: Multi-perspective visual servoing for improving object views with semantic segmentation | In this paper, we present a new approach to visual servoing for robotics,
referred to as 3D Move to See (3DMTS), based on the principle of finding the
next best view using a 3D camera array and a robotic manipulator to obtain
multiple samples of the scene from different perspectives. The method uses
semantic vision and an objective function applied to each perspective to sample
a gradient representing the direction of the next best view. The method is
demonstrated within simulation and on a real robotic platform containing a
custom 3D camera array for the challenging scenario of robotic harvesting in a
highly occluded and unstructured environment. It was shown on a real robotic
platform that by moving the end effector using the gradient of an objective
function leads to a locally optimal view of the object of interest, even
amongst occlusions. The overall performance of the 3DMTS method obtained a mean
increase in target size by 29.3% compared to a baseline method using a single
RGB-D camera, which obtained 9.17%. The results demonstrate qualitatively and
quantitatively that the 3DMTS method performed better in most scenarios, and
yielded three times the target size compared to the baseline method. The
increased target size in the final view will improve the detection of key
features of the object of interest for further manipulation, such as grasping
and harvesting.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,167 | Modeling influenza-like illnesses through composite compartmental models | Epidemiological models for the spread of pathogens in a population are
usually only able to describe a single pathogen. This makes their application
unrealistic in cases where multiple pathogens with similar symptoms are
spreading concurrently within the same population. Here we describe a method
which makes possible the application of multiple single-strain models under
minimal conditions. As such, our method provides a bridge between theoretical
models of epidemiology and data-driven approaches for modeling of influenza and
other similar viruses.
Our model extends the Susceptible-Infected-Recovered model to higher
dimensions, allowing the modeling of a population infected by multiple viruses.
We further provide a method, based on an overcomplete dictionary of feasible
realizations of SIR solutions, to blindly partition the time series
representing the number of infected people in a population into individual
components, each representing the effect of a single pathogen.
We demonstrate the applicability of our proposed method on five years of
seasonal influenza-like illness (ILI) rates, estimated from Twitter data. We
demonstrate that our method describes, on average, 44\% of the variance in the
ILI time series. The individual infectious components derived from our model
are matched to known viral profiles in the populations, which we demonstrate
matches that of independently collected epidemiological data. We further show
that the basic reproductive numbers ($R0$) of the matched components are in
range known for these pathogens.
Our results suggest that the proposed method can be applied to other
pathogens and geographies, providing a simple method for estimating the
parameters of epidemics in a population.
| 1 | 1 | 0 | 0 | 0 | 0 |
17,168 | Notes on the Polish Algorithm | We study, with the help of a computer program, the Polish Algorithm for
finite terms satisfying various algebraic laws, e.g., left distributivity a(bc)
= (ab)(ac). While the termination of the algorithm for left distributivity
remains open in general, we can establish some partial results, which might be
useful towards a positive solution. In contrast, we show the divergence of the
algorithm for the laws a(bc) = (ab)(cc) and a(bc) = (ab)(a(ac)).
| 0 | 0 | 1 | 0 | 0 | 0 |
17,169 | Penalized Maximum Tangent Likelihood Estimation and Robust Variable Selection | We introduce a new class of mean regression estimators -- penalized maximum
tangent likelihood estimation -- for high-dimensional regression estimation and
variable selection. We first explain the motivations for the key ingredient,
maximum tangent likelihood estimation (MTE), and establish its asymptotic
properties. We further propose a penalized MTE for variable selection and show
that it is $\sqrt{n}$-consistent, enjoys the oracle property. The proposed
class of estimators consists penalized $\ell_2$ distance, penalized exponential
squared loss, penalized least trimmed square and penalized least square as
special cases and can be regarded as a mixture of minimum Kullback-Leibler
distance estimation and minimum $\ell_2$ distance estimation. Furthermore, we
consider the proposed class of estimators under the high-dimensional setting
when the number of variables $d$ can grow exponentially with the sample size
$n$, and show that the entire class of estimators (including the aforementioned
special cases) can achieve the optimal rate of convergence in the order of
$\sqrt{\ln(d)/n}$. Finally, simulation studies and real data analysis
demonstrate the advantages of the penalized MTE.
| 0 | 0 | 0 | 1 | 0 | 0 |
17,170 | A minimally-dissipative low-Mach number solver for complex reacting flows in OpenFOAM | Large eddy simulation (LES) has become the de-facto computational tool for
modeling complex reacting flows, especially in gas turbine applications.
However, readily usable general-purpose LES codes for complex geometries are
typically academic or proprietary/commercial in nature. The objective of this
work is to develop and disseminate an open source LES tool for low-Mach number
turbulent combustion using the OpenFOAM framework. In particular, a
collocated-mesh approach suited for unstructured grid formulation is provided.
Unlike other fluid dynamics models, LES accuracy is intricately linked to
so-called primary and secondary conservation properties of the numerical
discretization schemes. This implies that although the solver only evolves
equations for mass, momentum, and energy, the implied discrete equation for
kinetic energy (square of velocity) should be minimally-dissipative. Here, a
specific spatial and temporal discretization is imposed such that this kinetic
energy dissipation is minimized. The method is demonstrated using manufactured
solutions approach on regular and skewed meshes, a canonical flow problem, and
a turbulent sooting flame in a complex domain relevant to gas turbines
applications.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,171 | Surface energy of strained amorphous solids | Surface stress and surface energy are fundamental quantities which
characterize the interface between two materials. Although these quantities are
identical for interfaces involving only fluids, the Shuttleworth effect
demonstrates that this is not the case for most interfaces involving solids,
since their surface energies change with strain. Crystalline materials are
known to have strain dependent surface energies, but in amorphous materials,
such as polymeric glasses and elastomers, the strain dependence is debated due
to a dearth of direct measurements. Here, we utilize contact angle measurements
on strained glassy and elastomeric solids to address this matter. We show
conclusively that interfaces involving polymeric glasses exhibit strain
dependent surface energies, and give strong evidence for the absence of such a
dependence for incompressible elastomers. The results provide fundamental
insight into our understanding of the interfaces of amorphous solids and their
interaction with contacting liquids.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,172 | Biaxial magnetic field setup for angular magnetic measurements of thin films and spintronic nanodevices | The biaxial magnetic-field setup for angular magnetic measurements of thin
film and spintronic devices is designed and presented. The setup allows for
application of the in-plane magnetic field using a quadrupole electromagnet,
controlled by power supply units and integrated with an electromagnet biaxial
magnetic field sensor. In addition, the probe station is equipped with a
microwave circuitry, which enables angle-resolved spin torque oscillation
measurements. The angular dependencies of magnetoresistance and spin diode
effect in a giant magnetoresistance strip are shown as an operational
verification of the experimental setup. We adapted an analytical macrospin
model to reproduce both the resistance and spin-diode angular dependency
measurements.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,173 | Active matter invasion of a viscous fluid: unstable sheets and a no-flow theorem | We investigate the dynamics of a dilute suspension of hydrodynamically
interacting motile or immotile stress-generating swimmers or particles as they
invade a surrounding viscous fluid. Colonies of aligned pusher particles are
shown to elongate in the direction of particle orientation and undergo a
cascade of transverse concentration instabilities, governed at small times by
an equation which also describes the Saffman-Taylor instability in a Hele-Shaw
cell, or Rayleigh-Taylor instability in two-dimensional flow through a porous
medium. Thin sheets of aligned pusher particles are always unstable, while
sheets of aligned puller particles can either be stable (immotile particles),
or unstable (motile particles) with a growth rate which is non-monotonic in the
force dipole strength. We also prove a surprising "no-flow theorem": a
distribution initially isotropic in orientation loses isotropy immediately but
in such a way that results in no fluid flow everywhere and for all time.
| 0 | 0 | 0 | 0 | 1 | 0 |
17,174 | Interplay of synergy and redundancy in diamond motif | The formalism of partial information decomposition provides independent or
non-overlapping components constituting total information content provided by a
set of source variables about the target variable. These components are
recognised as unique information, synergistic information and, redundant
information. The metric of net synergy, conceived as the difference between
synergistic and redundant information, is capable of detecting synergy,
redundancy and, information independence among stochastic variables. And it can
be quantified, as it is done here, using appropriate combinations of different
Shannon mutual information terms. Utilisation of such a metric in network
motifs with the nodes representing different biochemical species, involved in
information sharing, uncovers rich store for interesting results. In the
current study, we make use of this formalism to obtain a comprehensive
understanding of the relative information processing mechanism in a diamond
motif and two of its sub-motifs namely bifurcation and integration motif
embedded within the diamond motif. The emerging patterns of synergy and
redundancy and their effective contribution towards ensuring high fidelity
information transmission are duly compared in the sub-motifs and independent
motifs (bifurcation and integration). In this context, the crucial roles played
by various time scales and activation coefficients in the network topologies
are especially emphasised. We show that the origin of synergy and redundancy in
information transmission can be physically justified by decomposing diamond
motif into bifurcation and integration motif.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,175 | Hardy-Sobolev equations with asymptotically vanishing singularity: Blow-up analysis for the minimal energy | We study the asymptotic behavior of a sequence of positive solutions
$(u_{\epsilon})_{\epsilon >0}$ as $\epsilon \to 0$ to the family of equations
\begin{equation*} \left\{\begin{array}{ll} \Delta
u_{\epsilon}+a(x)u_{\epsilon}=
\frac{u_{\epsilon}^{2^*(s_{\epsilon})-1}}{|x|^{s_{\epsilon}}}& \hbox{ in
}\Omega\\ u_{\epsilon}=0 & \hbox{ on }\partial\Omega. \end{array}\right.
\end{equation*} where $(s_{\epsilon})_{\epsilon >0}$ is a sequence of positive
real numbers such that $\lim \limits_{\epsilon \rightarrow 0} s_{\epsilon}=0$,
$2^{*}(s_{\epsilon}):= \frac{2(n-s_{\epsilon})}{n-2}$ and $\Omega \subset
\mathbb{R}^{n}$ is a bounded smooth domain such that $0 \in \partial \Omega$.
When the sequence $(u_{\epsilon})_{\epsilon >0}$ is uniformly bounded in
$L^{\infty}$, then upto a subsequence it converges strongly to a minimizing
solution of the stationary Schrödinger equation with critical growth. In
case the sequence blows up, we obtain strong pointwise control on the blow up
sequence, and then using the Pohozaev identity localize the point of
singularity, which in this case can at most be one, and derive precise blow up
rates. In particular when $n=3$ or $a\equiv 0$ then blow up can occur only at
an interior point of $\Omega$ or the point $0 \in \partial \Omega$.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,176 | Some results on Ricatti Equations, Floquet Theory and Applications | In this paper, we present two new results to the classical Floquet theory,
which provides the Floquet multipliers for two classes of the planar periodic
system. One these results provides the Floquet multipliers independently of the
solution of system. To demonstrate the application of these analytical results,
we consider a cholera epidemic model with phage dynamics and seasonality
incorporated.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,177 | Size, Shape, and Phase Control in Ultrathin CdSe Nanosheets | Ultrathin two-dimensional nanosheets raise a rapidly increasing interest due
to their unique dimensionality-dependent properties. Most of the
two-dimensional materials are obtained by exfoliation of layered bulk materials
or are grown on substrates by vapor deposition methods. To produce
free-standing nanosheets, solution-based colloidal methods are emerging as
promising routes. In this work, we demonstrate ultrathin CdSe nanosheets with
controllable size, shape and phase. The key of our approach is the use of
halogenated alkanes as additives in a hot-injection synthesis. Increasing
concentrations of bromoalkanes can tune the shape from sexangular to
quadrangular to triangular and the phase from zinc blende to wurtzite. Geometry
and crystal structure evolution of the nanosheets take place in the presence of
halide ions, acting as cadmium complexing agents and as surface X-type ligands,
according to mass spectrometry and X-ray photoelectron spectroscopies. Our
experimental findings show that the degree of these changes depends on the
molecular structure of the halogen alkanes and the type of halogen atom.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,178 | Transfer of magnetic order and anisotropy through epitaxial integration of 3$d$ and 4$f$ spin systems | Resonant x-ray scattering at the Dy $M_5$ and Ni $L_3$ absorption edges was
used to probe the temperature and magnetic field dependence of magnetic order
in epitaxial LaNiO$_3$-DyScO$_3$ superlattices. For superlattices with 2 unit
cell thick LaNiO$_3$ layers, a commensurate spiral state develops in the Ni
spin system below 100 K. Upon cooling below $T_{ind} = 18$ K, Dy-Ni exchange
interactions across the LaNiO$_3$-DyScO$_3$ interfaces induce collinear
magnetic order of interfacial Dy moments as well as a reorientation of the Ni
spins to a direction dictated by the strong magneto-crystalline anisotropy of
Dy. This transition is reversible by an external magnetic field of 3 T.
Tailored exchange interactions between rare-earth and transition-metal ions
thus open up new perspectives for the manipulation of spin structures in
metal-oxide heterostructures and devices.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,179 | Exotic limit sets of Teichmüller geodesics in the HHS boundary | We answer a question of Durham, Hagen, and Sisto, proving that a
Teichmüller geodesic ray does not necessarily converge to a unique point in
the hierarchically hyperbolic space boundary of Teichmüller space. In fact,
we prove that the limit set can be almost anything allowed by the topology.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,180 | Decoupling "when to update" from "how to update" | Deep learning requires data. A useful approach to obtain data is to be
creative and mine data from various sources, that were created for different
purposes. Unfortunately, this approach often leads to noisy labels. In this
paper, we propose a meta algorithm for tackling the noisy labels problem. The
key idea is to decouple "when to update" from "how to update". We demonstrate
the effectiveness of our algorithm by mining data for gender classification by
combining the Labeled Faces in the Wild (LFW) face recognition dataset with a
textual genderizing service, which leads to a noisy dataset. While our approach
is very simple to implement, it leads to state-of-the-art results. We analyze
some convergence properties of the proposed algorithm.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,181 | Advection of potential temperature in the atmosphere of irradiated exoplanets: a robust mechanism to explain radius inflation | The anomalously large radii of strongly irradiated exoplanets have remained a
major puzzle in astronomy. Based on a 2D steady state atmospheric circulation
model, the validity of which is assessed by comparison to 3D calculations, we
reveal a new mechanism, namely the advection of the potential temperature due
to mass and longitudinal momentum conservation, a process occuring in the
Earth's atmosphere or oceans. At depth, the vanishing heating flux forces the
atmospheric structure to converge to a hotter adiabat than the one obtained
with 1D calculations, implying a larger radius for the planet. Not only do the
calculations reproduce the observed radius of HD209458b, but also the observed
correlation between radius inflation and irradiation for transiting planets.
Vertical advection of potential temperature induced by non uniform atmospheric
heating thus provides a robust mechanism explaining the inflated radii of
irradiated hot Jupiters.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,182 | Band depths based on multiple time instances | Bands of vector-valued functions $f:T\mapsto\mathbb{R}^d$ are defined by
considering convex hulls generated by their values concatenated at $m$
different values of the argument. The obtained $m$-bands are families of
functions, ranging from the conventional band in case the time points are
individually considered (for $m=1$) to the convex hull in the functional space
if the number $m$ of simultaneously considered time points becomes large enough
to fill the whole time domain. These bands give rise to a depth concept that is
new both for real-valued and vector-valued functions.
| 0 | 0 | 1 | 1 | 0 | 0 |
17,183 | On Biased Correlation Estimation | In general, underestimation of risk is something which should be avoided as
far as possible. Especially in financial asset management, equity risk is
typically characterized by the measure of portfolio variance, or indirectly by
quantities which are derived from it. Since there is a linear dependency of the
variance and the empirical correlation between asset classes, one is compelled
to control or to avoid the possibility of underestimating correlation
coefficients. In the present approach, we formalize common practice and
classify these approaches by computing their probability of underestimation. In
addition, we introduce a new estimator which is characterized by having the
advantage of a constant and controllable probability of underestimation. We
prove that the new estimator is statistically consistent.
| 0 | 0 | 1 | 1 | 0 | 0 |
17,184 | Atomic Swaptions: Cryptocurrency Derivatives | The atomic swap protocol allows for the exchange of cryptocurrencies on
different blockchains without the need to trust a third-party. However, market
participants who desire to hold derivative assets such as options or futures
would also benefit from trustless exchange. In this paper I propose the atomic
swaption, which extends the atomic swap to allow for such exchanges. Crucially,
atomic swaptions do not require the use of oracles. I also introduce the margin
contract, which provides the ability to create leveraged and short positions.
Lastly, I discuss how atomic swaptions may be routed on the Lightning Network.
| 0 | 0 | 0 | 0 | 0 | 1 |
17,185 | An arbitrary order scheme on generic meshes for miscible displacements in porous media | We design, analyse and implement an arbitrary order scheme applicable to
generic meshes for a coupled elliptic-parabolic PDE system describing miscible
displacement in porous media. The discretisation is based on several
adaptations of the Hybrid-High-Order (HHO) method due to Di Pietro et al.
[Computational Methods in Applied Mathematics, 14(4), (2014)]. The equation
governing the pressure is discretised using an adaptation of the HHO method for
variable diffusion, while the discrete concentration equation is based on the
HHO method for advection-diffusion-reaction problems combined with numerically
stable flux reconstructions for the advective velocity that we have derived
using the results of Cockburn et al. [ESAIM: Mathematical Modelling and
Numerical Analysis, 50(3), (2016)]. We perform some rigorous analysis of the
method to demonstrate its $L^2$ stability under the irregular data often
presented by reservoir engineering problems and present several numerical tests
to demonstrate the quality of the results that are produced by the proposed
scheme.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,186 | Parametricity, automorphisms of the universe, and excluded middle | It is known that one can construct non-parametric functions by assuming
classical axioms. Our work is a converse to that: we prove classical axioms in
dependent type theory assuming specific instances of non-parametricity. We also
address the interaction between classical axioms and the existence of
automorphisms of a type universe. We work over intensional Martin-Löf
dependent type theory, and in some results assume further principles including
function extensionality, propositional extensionality, propositional
truncation, and the univalence axiom.
| 1 | 0 | 1 | 0 | 0 | 0 |
17,187 | Convergence Rates for Deterministic and Stochastic Subgradient Methods Without Lipschitz Continuity | We extend the classic convergence rate theory for subgradient methods to
apply to non-Lipschitz functions. For the deterministic projected subgradient
method, we present a global $O(1/\sqrt{T})$ convergence rate for any convex
function which is locally Lipschitz around its minimizers. This approach is
based on Shor's classic subgradient analysis and implies generalizations of the
standard convergence rates for gradient descent on functions with Lipschitz or
Hölder continuous gradients. Further, we show a $O(1/\sqrt{T})$ convergence
rate for the stochastic projected subgradient method on convex functions with
at most quadratic growth, which improves to $O(1/T)$ under either strong
convexity or a weaker quadratic lower bound condition.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,188 | A quantum dynamics method for excited electrons in molecular aggregate system using a group diabatic Fock matrix | We introduce a practical calculation scheme for the description of excited
electron dynamics in molecular aggregated systems within a locally group
diabatic Fock representation. This scheme makes it easy to analyze the
interacting time-dependent excitations of local sites in complex systems. In
addition, light-electron couplings are considered. The present scheme is
intended for investigations on the migration dynamics of excited electrons in
light-energy conversion systems. The scheme was applied to two systems: a
naphthalene(NPTL)-tetracyanoethylene(TCNE) dimer and a 20-mer circle of
ethylene molecules. Through local group analyses of the dynamical electrons, we
obtained an intuitive understanding of the electron transfers between the
monomers.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,189 | Products of topological groups in which all closed subgroups are separable | We prove that if $H$ is a topological group such that all closed subgroups of
$H$ are separable, then the product $G\times H$ has the same property for every
separable compact group $G$.
Let $c$ be the cardinality of the continuum. Assuming $2^{\omega_1} = c$, we
show that there exist:
(1) pseudocompact topological abelian groups $G$ and $H$ such that all closed
subgroups of $G$ and $H$ are separable, but the product $G\times H$ contains a
closed non-separable $\sigma$-compact subgroup;
(2) pseudocomplete locally convex vector spaces $K$ and $L$ such that all
closed vector subspaces of $K$ and $L$ are separable, but the product $K\times
L$ contains a closed non-separable $\sigma$-compact vector subspace.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,190 | Low rank solutions to differentiable systems over matrices and applications | Differentiable systems in this paper means systems of equations that are
described by differentiable real functions in real matrix variables. This paper
proposes algorithms for finding minimal rank solutions to such systems over
(arbitrary and/or several structured) matrices by using the Levenberg-Marquardt
method (LM-method) for solving least squares problems. We then apply these
algorithms to solve several engineering problems such as the low-rank matrix
completion problem and the low-dimensional Euclidean embedding one. Some
numerical experiments illustrate the validity of the approach.
On the other hand, we provide some further properties of low rank solutions
to systems linear matrix equations. This is useful when the differentiable
function is linear or quadratic.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,191 | A Simple and Realistic Pedestrian Model for Crowd Simulation and Application | The simulation of pedestrian crowd that reflects reality is a major challenge
for researches. Several crowd simulation models have been proposed such as
cellular automata model, agent-based model, fluid dynamic model, etc. It is
important to note that agent-based model is able, over others approaches, to
provide a natural description of the system and then to capture complex human
behaviors. In this paper, we propose a multi-agent simulation model in which
pedestrian positions are updated at discrete time intervals. It takes into
account the major normal conditions of a simple pedestrian situated in a crowd
such as preferences, realistic perception of environment, etc. Our objective is
to simulate the pedestrian crowd realistically towards a simulation of
believable pedestrian behaviors. Typical pedestrian phenomena, including the
unidirectional and bidirectional movement in a corridor as well as the flow
through bottleneck, are simulated. The conducted simulations show that our
model is able to produce realistic pedestrian behaviors. The obtained
fundamental diagram and flow rate at bottleneck agree very well with classic
conclusions and empirical study results. It is hoped that the idea of this
study may be helpful in promoting the modeling and simulation of pedestrian
crowd in a simple way.
| 1 | 1 | 0 | 0 | 0 | 0 |
17,192 | Local connectivity modulates multi-scale relaxation dynamics in a metallic glass-forming system | The structural description for the intriguing link between the fast
vibrational dynamics and slow diffusive dynamics in glass-forming systems is
one of the most challenging issues in physical science. Here, in a model of
metallic supercooled liquid, we find that local connectivity as an atomic-level
structural order parameter tunes the short-time vibrational excitations of the
icosahedrally coordinated particles and meanwhile modulates their long-time
relaxation dynamics changing from stretched to compressed exponentials,
denoting a dynamic transition from subdiffusive to hyperdiffusive motions of
such particles. Our result indicates that long-time dynamics has an
atomic-level structural origin which is related to the short-time dynamics,
thus suggests a structural bridge to link the fast vibrational dynamics and the
slow structural relaxation in glassy materials.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,193 | SATR-DL: Improving Surgical Skill Assessment and Task Recognition in Robot-assisted Surgery with Deep Neural Networks | Purpose: This paper focuses on an automated analysis of surgical motion
profiles for objective skill assessment and task recognition in robot-assisted
surgery. Existing techniques heavily rely on conventional statistic measures or
shallow modelings based on hand-engineered features and gesture segmentation.
Such developments require significant expert knowledge, are prone to errors,
and are less efficient in online adaptive training systems. Methods: In this
work, we present an efficient analytic framework with a parallel deep learning
architecture, SATR-DL, to assess trainee expertise and recognize surgical
training activity. Through an end-to-end learning technique, abstract
information of spatial representations and temporal dynamics is jointly
obtained directly from raw motion sequences. Results: By leveraging a shared
high-level representation learning, the resulting model is successful in the
recognition of trainee skills and surgical tasks, suturing, needle-passing, and
knot-tying. Meanwhile, we explore the use of ensemble in classification at the
trial level, where the SATR-DL outperforms state-of-the-art performance by
achieving accuracies of 0.960 and 1.000 in skill assessment and task
recognition, respectively. Conclusion: This study highlights the potential of
SATR-DL to provide improvements for an efficient data-driven assessment in
intelligent robotic surgery.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,194 | Equivalence of weak and strong modes of measures on topological vector spaces | A strong mode of a probability measure on a normed space $X$ can be defined
as a point $u$ such that the mass of the ball centred at $u$ uniformly
dominates the mass of all other balls in the small-radius limit. Helin and
Burger weakened this definition by considering only pairwise comparisons with
balls whose centres differ by vectors in a dense, proper linear subspace $E$ of
$X$, and posed the question of when these two types of modes coincide. We show
that, in a more general setting of metrisable vector spaces equipped with
measures that are finite on bounded sets, the density of $E$ and a uniformity
condition suffice for the equivalence of these two types of modes. We
accomplish this by introducing a new, intermediate type of mode. We also show
that these modes can be inequivalent if the uniformity condition fails. Our
results shed light on the relationships between among various notions of
maximum a posteriori estimator in non-parametric Bayesian inference.
| 0 | 0 | 1 | 1 | 0 | 0 |
17,195 | Algebras of Quasi-Plücker Coordinates are Koszul | Motivated by the theory of quasi-determinants, we study non-commutative
algebras of quasi-Plücker coordinates. We prove that these algebras provide
new examples of non-homogeneous quadratic Koszul algebras by showing that their
quadratic duals have quadratic Gröbner bases.
| 0 | 0 | 1 | 0 | 0 | 0 |
17,196 | Doubly-Attentive Decoder for Multi-modal Neural Machine Translation | We introduce a Multi-modal Neural Machine Translation model in which a
doubly-attentive decoder naturally incorporates spatial visual features
obtained using pre-trained convolutional neural networks, bridging the gap
between image description and translation. Our decoder learns to attend to
source-language words and parts of an image independently by means of two
separate attention mechanisms as it generates words in the target language. We
find that our model can efficiently exploit not just back-translated in-domain
multi-modal data but also large general-domain text-only MT corpora. We also
report state-of-the-art results on the Multi30k data set.
| 1 | 0 | 0 | 0 | 0 | 0 |
17,197 | prDeep: Robust Phase Retrieval with a Flexible Deep Network | Phase retrieval algorithms have become an important component in many modern
computational imaging systems. For instance, in the context of ptychography and
speckle correlation imaging, they enable imaging past the diffraction limit and
through scattering media, respectively. Unfortunately, traditional phase
retrieval algorithms struggle in the presence of noise. Progress has been made
recently on more robust algorithms using signal priors, but at the expense of
limiting the range of supported measurement models (e.g., to Gaussian or coded
diffraction patterns). In this work we leverage the regularization-by-denoising
framework and a convolutional neural network denoiser to create prDeep, a new
phase retrieval algorithm that is both robust and broadly applicable. We test
and validate prDeep in simulation to demonstrate that it is robust to noise and
can handle a variety of system models.
A MatConvNet implementation of prDeep is available at
this https URL.
| 0 | 0 | 0 | 1 | 0 | 0 |
17,198 | Novel Exotic Magnetic Spin-order in Co5Ge3 Nano-size Materials | The Cobalt-germanium (Co-Ge) is a fascinating complex alloy system that has
unique structure and exhibit range of interesting magnetic properties which
would change when reduce to nanoscale dimension. At this experimental work, the
high-aspect-ratio Co5Ge3 nanoparticle with average size of 8nm was synthesized
by gas aggregation-type cluster-deposition technology. The nanostructure
morphology of the as-made binary Co5Ge3 nanoparticles demonstrate excellent
single-crystalline hexagonal structure with mostly preferable growth along
(110) and (102) directions. In contrast the bulk possess Pauli paramagnetic
spin-order at all range of temperature, here we discover size-driven new
magnetic ordering of as-synthesized Co5Ge3 nanoparticles exhibiting
ferromagnetism at room temperature with saturation magnetization of Ms = 32.2
emu/cm3. This is first report of observing such new magnetic spin ordering in
this kind of material at nano-size which the magnetization has lower
sensitivity to thermal energy fluctuation and exhibit high Curie temperature
close to 850 K. This ferromagnetic behavior along with higher Curie temperature
at Co5Ge3 nanoparticles are attributes to low-dimension and quantum-confinement
effect which imposes strong spin coupling and provides a new set of size-driven
spin structures in Co5Ge3 nanoparticle which no such magnetic behavior being
present in the bulk of same material. This fundamental scientific study
provides important insights into the formation, structural, and the magnetic
property of sub 10nm Co5Ge3 nanostructure which shall lead to promising
practical versatile applications for magneto- germanide based nano-devices.
| 0 | 1 | 0 | 0 | 0 | 0 |
17,199 | Toward Multimodal Image-to-Image Translation | Many image-to-image translation problems are ambiguous, as a single input
image may correspond to multiple possible outputs. In this work, we aim to
model a \emph{distribution} of possible outputs in a conditional generative
modeling setting. The ambiguity of the mapping is distilled in a
low-dimensional latent vector, which can be randomly sampled at test time. A
generator learns to map the given input, combined with this latent code, to the
output. We explicitly encourage the connection between output and the latent
code to be invertible. This helps prevent a many-to-one mapping from the latent
code to the output during training, also known as the problem of mode collapse,
and produces more diverse results. We explore several variants of this approach
by employing different training objectives, network architectures, and methods
of injecting the latent code. Our proposed method encourages bijective
consistency between the latent encoding and output modes. We present a
systematic comparison of our method and other variants on both perceptual
realism and diversity.
| 1 | 0 | 0 | 1 | 0 | 0 |
17,200 | On the Sample Complexity of the Linear Quadratic Regulator | This paper addresses the optimal control problem known as the Linear
Quadratic Regulator in the case when the dynamics are unknown. We propose a
multi-stage procedure, called Coarse-ID control, that estimates a model from a
few experimental trials, estimates the error in that model with respect to the
truth, and then designs a controller using both the model and uncertainty
estimate. Our technique uses contemporary tools from random matrix theory to
bound the error in the estimation procedure. We also employ a recently
developed approach to control synthesis called System Level Synthesis that
enables robust control design by solving a convex optimization problem. We
provide end-to-end bounds on the relative error in control cost that are nearly
optimal in the number of parameters and that highlight salient properties of
the system to be controlled such as closed-loop sensitivity and optimal control
magnitude. We show experimentally that the Coarse-ID approach enables efficient
computation of a stabilizing controller in regimes where simple control schemes
that do not take the model uncertainty into account fail to stabilize the true
system.
| 1 | 0 | 0 | 1 | 0 | 0 |
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