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1 | Reconstructing Subject-Specific Effect Maps | Predictive models allow subject-specific inference when analyzing disease
related alterations in neuroimaging data. Given a subject's data, inference can
be made at two levels: global, i.e. identifiying condition presence for the
subject, and local, i.e. detecting condition effect on each individual
measurement extracted from the subject's data. While global inference is widely
used, local inference, which can be used to form subject-specific effect maps,
is rarely used because existing models often yield noisy detections composed of
dispersed isolated islands. In this article, we propose a reconstruction
method, named RSM, to improve subject-specific detections of predictive
modeling approaches and in particular, binary classifiers. RSM specifically
aims to reduce noise due to sampling error associated with using a finite
sample of examples to train classifiers. The proposed method is a wrapper-type
algorithm that can be used with different binary classifiers in a diagnostic
manner, i.e. without information on condition presence. Reconstruction is posed
as a Maximum-A-Posteriori problem with a prior model whose parameters are
estimated from training data in a classifier-specific fashion. Experimental
evaluation is performed on synthetically generated data and data from the
Alzheimer's Disease Neuroimaging Initiative (ADNI) database. Results on
synthetic data demonstrate that using RSM yields higher detection accuracy
compared to using models directly or with bootstrap averaging. Analyses on the
ADNI dataset show that RSM can also improve correlation between
subject-specific detections in cortical thickness data and non-imaging markers
of Alzheimer's Disease (AD), such as the Mini Mental State Examination Score
and Cerebrospinal Fluid amyloid-$\beta$ levels. Further reliability studies on
the longitudinal ADNI dataset show improvement on detection reliability when
RSM is used.
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2 | Rotation Invariance Neural Network | Rotation invariance and translation invariance have great values in image
recognition tasks. In this paper, we bring a new architecture in convolutional
neural network (CNN) named cyclic convolutional layer to achieve rotation
invariance in 2-D symbol recognition. We can also get the position and
orientation of the 2-D symbol by the network to achieve detection purpose for
multiple non-overlap target. Last but not least, this architecture can achieve
one-shot learning in some cases using those invariance.
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3 | Spherical polyharmonics and Poisson kernels for polyharmonic functions | We introduce and develop the notion of spherical polyharmonics, which are a
natural generalisation of spherical harmonics. In particular we study the
theory of zonal polyharmonics, which allows us, analogously to zonal harmonics,
to construct Poisson kernels for polyharmonic functions on the union of rotated
balls. We find the representation of Poisson kernels and zonal polyharmonics in
terms of the Gegenbauer polynomials. We show the connection between the
classical Poisson kernel for harmonic functions on the ball, Poisson kernels
for polyharmonic functions on the union of rotated balls, and the Cauchy-Hua
kernel for holomorphic functions on the Lie ball.
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4 | A finite element approximation for the stochastic Maxwell--Landau--Lifshitz--Gilbert system | The stochastic Landau--Lifshitz--Gilbert (LLG) equation coupled with the
Maxwell equations (the so called stochastic MLLG system) describes the creation
of domain walls and vortices (fundamental objects for the novel nanostructured
magnetic memories). We first reformulate the stochastic LLG equation into an
equation with time-differentiable solutions. We then propose a convergent
$\theta$-linear scheme to approximate the solutions of the reformulated system.
As a consequence, we prove convergence of the approximate solutions, with no or
minor conditions on time and space steps (depending on the value of $\theta$).
Hence, we prove the existence of weak martingale solutions of the stochastic
MLLG system. Numerical results are presented to show applicability of the
method.
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5 | Comparative study of Discrete Wavelet Transforms and Wavelet Tensor Train decomposition to feature extraction of FTIR data of medicinal plants | Fourier-transform infra-red (FTIR) spectra of samples from 7 plant species
were used to explore the influence of preprocessing and feature extraction on
efficiency of machine learning algorithms. Wavelet Tensor Train (WTT) and
Discrete Wavelet Transforms (DWT) were compared as feature extraction
techniques for FTIR data of medicinal plants. Various combinations of signal
processing steps showed different behavior when applied to classification and
clustering tasks. Best results for WTT and DWT found through grid search were
similar, significantly improving quality of clustering as well as
classification accuracy for tuned logistic regression in comparison to original
spectra. Unlike DWT, WTT has only one parameter to be tuned (rank), making it a
more versatile and easier to use as a data processing tool in various signal
processing applications.
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6 | On maximizing the fundamental frequency of the complement of an obstacle | Let $\Omega \subset \mathbb{R}^n$ be a bounded domain satisfying a
Hayman-type asymmetry condition, and let $ D $ be an arbitrary bounded domain
referred to as "obstacle". We are interested in the behaviour of the first
Dirichlet eigenvalue $ \lambda_1(\Omega \setminus (x+D)) $. First, we prove an
upper bound on $ \lambda_1(\Omega \setminus (x+D)) $ in terms of the distance
of the set $ x+D $ to the set of maximum points $ x_0 $ of the first Dirichlet
ground state $ \phi_{\lambda_1} > 0 $ of $ \Omega $. In short, a direct
corollary is that if \begin{equation} \mu_\Omega := \max_{x}\lambda_1(\Omega
\setminus (x+D)) \end{equation} is large enough in terms of $ \lambda_1(\Omega)
$, then all maximizer sets $ x+D $ of $ \mu_\Omega $ are close to each maximum
point $ x_0 $ of $ \phi_{\lambda_1} $.
Second, we discuss the distribution of $ \phi_{\lambda_1(\Omega)} $ and the
possibility to inscribe wavelength balls at a given point in $ \Omega $.
Finally, we specify our observations to convex obstacles $ D $ and show that
if $ \mu_\Omega $ is sufficiently large with respect to $ \lambda_1(\Omega) $,
then all maximizers $ x+D $ of $ \mu_\Omega $ contain all maximum points $ x_0
$ of $ \phi_{\lambda_1(\Omega)} $.
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7 | On the rotation period and shape of the hyperbolic asteroid 1I/`Oumuamua (2017) U1 from its lightcurve | We observed the newly discovered hyperbolic minor planet 1I/`Oumuamua (2017
U1) on 2017 October 30 with Lowell Observatory's 4.3-m Discovery Channel
Telescope. From these observations, we derived a partial lightcurve with
peak-to-trough amplitude of at least 1.2 mag. This lightcurve segment rules out
rotation periods less than 3 hr and suggests that the period is at least 5 hr.
On the assumption that the variability is due to a changing cross section, the
axial ratio is at least 3:1. We saw no evidence for a coma or tail in either
individual images or in a stacked image having an equivalent exposure time of
9000 s.
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8 | Adverse effects of polymer coating on heat transport at solid-liquid interface | The ability of metallic nanoparticles to supply heat to a liquid environment
under exposure to an external optical field has attracted growing interest for
biomedical applications. Controlling the thermal transport properties at a
solid-liquid interface then appears to be particularly relevant. In this work,
we address the thermal transport between water and a gold surface coated by a
polymer layer. Using molecular dynamics simulations, we demonstrate that
increasing the polymer density displaces the domain resisting to the heat flow,
while it doesn't affect the final amount of thermal energy released in the
liquid. This unexpected behavior results from a trade-off established by the
increasing polymer density which couples more efficiently with the solid but
initiates a counterbalancing resistance with the liquid.
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9 | SPH calculations of Mars-scale collisions: the role of the Equation of State, material rheologies, and numerical effects | We model large-scale ($\approx$2000km) impacts on a Mars-like planet using a
Smoothed Particle Hydrodynamics code. The effects of material strength and of
using different Equations of State on the post-impact material and temperature
distributions are investigated. The properties of the ejected material in terms
of escaping and disc mass are analysed as well. We also study potential
numerical effects in the context of density discontinuities and rigid body
rotation. We find that in the large-scale collision regime considered here
(with impact velocities of 4km/s), the effect of material strength is
substantial for the post-impact distribution of the temperature and the
impactor material, while the influence of the Equation of State is more subtle
and present only at very high temperatures.
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10 | $\mathcal{R}_{0}$ fails to predict the outbreak potential in the presence of natural-boosting immunity | Time varying susceptibility of host at individual level due to waning and
boosting immunity is known to induce rich long-term behavior of disease
transmission dynamics. Meanwhile, the impact of the time varying heterogeneity
of host susceptibility on the shot-term behavior of epidemics is not
well-studied, even though the large amount of the available epidemiological
data are the short-term epidemics. Here we constructed a parsimonious
mathematical model describing the short-term transmission dynamics taking into
account natural-boosting immunity by reinfection, and obtained the explicit
solution for our model. We found that our system show "the delayed epidemic",
the epidemic takes off after negative slope of the epidemic curve at the
initial phase of epidemic, in addition to the common classification in the
standard SIR model, i.e., "no epidemic" as $\mathcal{R}_{0}\leq1$ or normal
epidemic as $\mathcal{R}_{0}>1$. Employing the explicit solution we derived the
condition for each classification.
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11 | A global sensitivity analysis and reduced order models for hydraulically-fractured horizontal wells | We present a systematic global sensitivity analysis using the Sobol method
which can be utilized to rank the variables that affect two quantity of
interests -- pore pressure depletion and stress change -- around a
hydraulically-fractured horizontal well based on their degree of importance.
These variables include rock properties and stimulation design variables. A
fully-coupled poroelastic hydraulic fracture model is used to account for pore
pressure and stress changes due to production. To ease the computational cost
of a simulator, we also provide reduced order models (ROMs), which can be used
to replace the complex numerical model with a rather simple analytical model,
for calculating the pore pressure and stresses at different locations around
hydraulic fractures. The main findings of this research are: (i) mobility,
production pressure, and fracture half-length are the main contributors to the
changes in the quantities of interest. The percentage of the contribution of
each parameter depends on the location with respect to pre-existing hydraulic
fractures and the quantity of interest. (ii) As the time progresses, the effect
of mobility decreases and the effect of production pressure increases. (iii)
These two variables are also dominant for horizontal stresses at large
distances from hydraulic fractures. (iv) At zones close to hydraulic fracture
tips or inside the spacing area, other parameters such as fracture spacing and
half-length are the dominant factors that affect the minimum horizontal stress.
The results of this study will provide useful guidelines for the stimulation
design of legacy wells and secondary operations such as refracturing and infill
drilling.
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12 | Role-separating ordering in social dilemmas controlled by topological frustration | "Three is a crowd" is an old proverb that applies as much to social
interactions, as it does to frustrated configurations in statistical physics
models. Accordingly, social relations within a triangle deserve special
attention. With this motivation, we explore the impact of topological
frustration on the evolutionary dynamics of the snowdrift game on a triangular
lattice. This topology provides an irreconcilable frustration, which prevents
anti-coordination of competing strategies that would be needed for an optimal
outcome of the game. By using different strategy updating protocols, we observe
complex spatial patterns in dependence on payoff values that are reminiscent to
a honeycomb-like organization, which helps to minimize the negative consequence
of the topological frustration. We relate the emergence of these patterns to
the microscopic dynamics of the evolutionary process, both by means of
mean-field approximations and Monte Carlo simulations. For comparison, we also
consider the same evolutionary dynamics on the square lattice, where of course
the topological frustration is absent. However, with the deletion of diagonal
links of the triangular lattice, we can gradually bridge the gap to the square
lattice. Interestingly, in this case the level of cooperation in the system is
a direct indicator of the level of topological frustration, thus providing a
method to determine frustration levels in an arbitrary interaction network.
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13 | Dynamics of exciton magnetic polarons in CdMnSe/CdMgSe quantum wells: the effect of self-localization | We study the exciton magnetic polaron (EMP) formation in (Cd,Mn)Se/(Cd,Mg)Se
diluted-magnetic-semiconductor quantum wells using time-resolved
photoluminescence (PL). The magnetic field and temperature dependencies of this
dynamics allow us to separate the non-magnetic and magnetic contributions to
the exciton localization. We deduce the EMP energy of 14 meV, which is in
agreement with time-integrated measurements based on selective excitation and
the magnetic field dependence of the PL circular polarization degree. The
polaron formation time of 500 ps is significantly longer than the corresponding
values reported earlier. We propose that this behavior is related to strong
self-localization of the EMP, accompanied with a squeezing of the heavy-hole
envelope wavefunction. This conclusion is also supported by the decrease of the
exciton lifetime from 600 ps to 200 - 400 ps with increasing magnetic field and
temperature.
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14 | On Varieties of Ordered Automata | The classical Eilenberg correspondence, based on the concept of the syntactic
monoid, relates varieties of regular languages with pseudovarieties of finite
monoids. Various modifications of this correspondence appeared, with more
general classes of regular languages on one hand and classes of more complex
algebraic structures on the other hand. For example, classes of languages need
not be closed under complementation or all preimages under homomorphisms, while
monoids can be equipped with a compatible order or they can have a
distinguished set of generators. Such generalized varieties and pseudovarieties
also have natural counterparts formed by classes of finite (ordered) automata.
In this paper the previous approaches are combined. The notion of positive
$\mathcal C$-varieties of ordered semiautomata (i.e. no initial and final
states are specified) is introduced and their correspondence with positive
$\mathcal C$-varieties of languages is proved.
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15 | Direct Evidence of Spontaneous Abrikosov Vortex State in Ferromagnetic Superconductor EuFe$_2$(As$_{1-x}$P$_x$)$_2$ with $x=0.21$ | Using low-temperature Magnetic Force Microscopy (MFM) we provide direct
experimental evidence for spontaneous vortex phase (SVP) formation in
EuFe$_2$(As$_{0.79}$P$_{0.21}$)$_2$ single crystal with the superconducting
$T^{\rm 0}_{\rm SC}=23.6$~K and ferromagnetic $T_{\rm FM}\sim17.7$~K transition
temperatures. Spontaneous vortex-antivortex (V-AV) pairs are imaged in the
vicinity of $T_{\rm FM}$. Also, upon cooling cycle near $T_{\rm FM}$ we observe
the first-order transition from the short period domain structure, which
appears in the Meissner state, into the long period domain structure with
spontaneous vortices. It is the first experimental observation of this scenario
in the ferromagnetic superconductors. Low-temperature phase is characterized by
much larger domains in V-AV state and peculiar branched striped structures at
the surface, which are typical for uniaxial ferromagnets with perpendicular
magnetic anisotropy (PMA). The domain wall parameters at various temperatures
are estimated.
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16 | A rank 18 Waring decomposition of $sM_{\langle 3\rangle}$ with 432 symmetries | The recent discovery that the exponent of matrix multiplication is determined
by the rank of the symmetrized matrix multiplication tensor has invigorated
interest in better understanding symmetrized matrix multiplication. I present
an explicit rank 18 Waring decomposition of $sM_{\langle 3\rangle}$ and
describe its symmetry group.
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17 | The PdBI Arcsecond Whirlpool Survey (PAWS). The Role of Spiral Arms in Cloud and Star Formation | The process that leads to the formation of the bright star forming sites
observed along prominent spiral arms remains elusive. We present results of a
multi-wavelength study of a spiral arm segment in the nearby grand-design
spiral galaxy M51 that belongs to a spiral density wave and exhibits nine gas
spurs. The combined observations of the(ionized, atomic, molecular, dusty)
interstellar medium (ISM) with star formation tracers (HII regions, young
<10Myr stellar clusters) suggest (1) no variation in giant molecular cloud
(GMC) properties between arm and gas spurs, (2) gas spurs and extinction
feathers arising from the same structure with a close spatial relation between
gas spurs and ongoing/recent star formation (despite higher gas surface
densities in the spiral arm), (3) no trend in star formation age either along
the arm or along a spur, (4) evidence for strong star formation feedback in gas
spurs: (5) tentative evidence for star formation triggered by stellar feedback
for one spur, and (6) GMC associations (GMAs) being no special entities but the
result of blending of gas arm/spur cross-sections in lower resolution
observations. We conclude that there is no evidence for a coherent star
formation onset mechanism that can be solely associated to the presence of the
spiral density wave. This suggests that other (more localized) mechanisms are
important to delay star formation such that it occurs in spurs. The evidence of
star formation proceeding over several million years within individual spurs
implies that the mechanism that leads to star formation acts or is sustained
over a longer time-scale.
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18 | Higher structure in the unstable Adams spectral sequence | We describe a variant construction of the unstable Adams spectral the
sequence for a space $Y$, associated to any free simplicial resolution of
$H^*(Y;R)$ for $R=\mathbb{F}_p$ or $\mathbb{Q}$. We use this construction to
describe the differentials and filtration in the spectral sequence in terms of
appropriate systems of higher cohomology operations.
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19 | Comparing Covariate Prioritization via Matching to Machine Learning Methods for Causal Inference using Five Empirical Applications | When investigators seek to estimate causal effects, they often assume that
selection into treatment is based only on observed covariates. Under this
identification strategy, analysts must adjust for observed confounders. While
basic regression models have long been the dominant method of statistical
adjustment, more robust methods based on matching or weighting have become more
common. Of late, even more flexible methods based on machine learning methods
have been developed for statistical adjustment. These machine learning methods
are designed to be black box methods with little input from the researcher.
Recent research used a data competition to evaluate various methods of
statistical adjustment and found that black box methods out performed all other
methods of statistical adjustment. Matching methods with covariate
prioritization are designed for direct input from substantive investigators in
direct contrast to black methods. In this article, we use a different research
design to compare matching with covariate prioritization to black box methods.
We use black box methods to replicate results from five studies where matching
with covariate prioritization was used to customize the statistical adjustment
in direct response to substantive expertise. We find little difference across
the methods. We conclude with advice for investigators.
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20 | Acoustic Impedance Calculation via Numerical Solution of the Inverse Helmholtz Problem | Assigning homogeneous boundary conditions, such as acoustic impedance, to the
thermoviscous wave equations (TWE) derived by transforming the linearized
Navier-Stokes equations (LNSE) to the frequency domain yields a so-called
Helmholtz solver, whose output is a discrete set of complex eigenfunction and
eigenvalue pairs. The proposed method -- the inverse Helmholtz solver (iHS) --
reverses such procedure by returning the value of acoustic impedance at one or
more unknown impedance boundaries (IBs) of a given domain via spatial
integration of the TWE for a given real-valued frequency with assigned
conditions on other boundaries. The iHS procedure is applied to a second-order
spatial discretization of the TWEs derived on an unstructured grid with
staggered grid arrangement. The momentum equation only is extended to the
center of each IB face where pressure and velocity components are co-located
and treated as unknowns. One closure condition considered for the iHS is the
assignment of the surface gradient of pressure phase over the IBs,
corresponding to assigning the shape of the acoustic waveform at the IB. The
iHS procedure is carried out independently for each frequency in order to
return the complete broadband complex impedance distribution at the IBs in any
desired frequency range. The iHS approach is first validated against Rott's
theory for both inviscid and viscous, rectangular and circular ducts. The
impedance of a geometrically complex toy cavity is then reconstructed and
verified against companion full compressible unstructured Navier-Stokes
simulations resolving the cavity geometry and one-dimensional impedance test
tube calculations based on time-domain impedance boundary conditions (TDIBC).
The iHS methodology is also shown to capture thermoacoustic effects, with
reconstructed impedance values quantitatively in agreement with thermoacoustic
growth rates.
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21 | Deciphering noise amplification and reduction in open chemical reaction networks | The impact of random fluctuations on the dynamical behavior a complex
biological systems is a longstanding issue, whose understanding would shed
light on the evolutionary pressure that nature imposes on the intrinsic noise
levels and would allow rationally designing synthetic networks with controlled
noise. Using the Itō stochastic differential equation formalism, we performed
both analytic and numerical analyses of several model systems containing
different molecular species in contact with the environment and interacting
with each other through mass-action kinetics. These systems represent for
example biomolecular oligomerization processes, complex-breakage reactions,
signaling cascades or metabolic networks. For chemical reaction networks with
zero deficiency values, which admit a detailed- or complex-balanced steady
state, all molecular species are uncorrelated. The number of molecules of each
species follow a Poisson distribution and their Fano factors, which measure the
intrinsic noise, are equal to one. Systems with deficiency one have an
unbalanced non-equilibrium steady state and a non-zero S-flux, defined as the
flux flowing between the complexes multiplied by an adequate stoichiometric
coefficient. In this case, the noise on each species is reduced if the flux
flows from the species of lowest to highest complexity, and is amplified is the
flux goes in the opposite direction. These results are generalized to systems
of deficiency two, which possess two independent non-vanishing S-fluxes, and we
conjecture that a similar relation holds for higher deficiency systems.
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22 | Many-Body Localization: Stability and Instability | Rare regions with weak disorder (Griffiths regions) have the potential to
spoil localization. We describe a non-perturbative construction of local
integrals of motion (LIOMs) for a weakly interacting spin chain in one
dimension, under a physically reasonable assumption on the statistics of
eigenvalues. We discuss ideas about the situation in higher dimensions, where
one can no longer ensure that interactions involving the Griffiths regions are
much smaller than the typical energy-level spacing for such regions. We argue
that ergodicity is restored in dimension d > 1, although equilibration should
be extremely slow, similar to the dynamics of glasses.
| 0 | 1 | 1 | 0 | 0 | 0 |
23 | Fault Detection and Isolation Tools (FDITOOLS) User's Guide | The Fault Detection and Isolation Tools (FDITOOLS) is a collection of MATLAB
functions for the analysis and solution of fault detection and model detection
problems. The implemented functions are based on the computational procedures
described in the Chapters 5, 6 and 7 of the book: "A. Varga, Solving Fault
Diagnosis Problems - Linear Synthesis Techniques, Springer, 2017". This
document is the User's Guide for the version V1.0 of FDITOOLS. First, we
present the mathematical background for solving several basic exact and
approximate synthesis problems of fault detection filters and model detection
filters. Then, we give in-depth information on the command syntax of the main
analysis and synthesis functions. Several examples illustrate the use of the
main functions of FDITOOLS.
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24 | Complexity of Deciding Detectability in Discrete Event Systems | Detectability of discrete event systems (DESs) is a question whether the
current and subsequent states can be determined based on observations. Shu and
Lin designed a polynomial-time algorithm to check strong (periodic)
detectability and an exponential-time (polynomial-space) algorithm to check
weak (periodic) detectability. Zhang showed that checking weak (periodic)
detectability is PSpace-complete. This intractable complexity opens a question
whether there are structurally simpler DESs for which the problem is tractable.
In this paper, we show that it is not the case by considering DESs represented
as deterministic finite automata without non-trivial cycles, which are
structurally the simplest deadlock-free DESs. We show that even for such very
simple DESs, checking weak (periodic) detectability remains intractable. On the
contrary, we show that strong (periodic) detectability of DESs can be
efficiently verified on a parallel computer.
| 1 | 0 | 0 | 0 | 0 | 0 |
25 | The Knaster-Tarski theorem versus monotone nonexpansive mappings | Let $X$ be a partially ordered set with the property that each family of
order intervals of the form $[a,b],[a,\rightarrow )$ with the finite
intersection property has a nonempty intersection. We show that every directed
subset of $X$ has a supremum. Then we apply the above result to prove that if
$X$ is a topological space with a partial order $\preceq $ for which the order
intervals are compact, $\mathcal{F}$ a nonempty commutative family of monotone
maps from $X$ into $X$ and there exists $c\in X$ such that $c\preceq Tc$ for
every $T\in \mathcal{F}$, then the set of common fixed points of $\mathcal{F}$
is nonempty and has a maximal element. The result, specialized to the case of
Banach spaces gives a general fixed point theorem that drops almost all
assumptions from the recent results in this area. An application to the theory
of integral equations of Urysohn's type is also given.
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26 | Efficient methods for computing integrals in electronic structure calculations | Efficient methods are proposed, for computing integrals appeaing in
electronic structure calculations. The methods consist of two parts: the first
part is to represent the integrals as contour integrals and the second one is
to evaluate the contour integrals by the Clenshaw-Curtis quadrature. The
efficiency of the proposed methods is demonstrated through numerical
experiments.
| 0 | 1 | 0 | 0 | 0 | 0 |
27 | Diffraction-Aware Sound Localization for a Non-Line-of-Sight Source | We present a novel sound localization algorithm for a non-line-of-sight
(NLOS) sound source in indoor environments. Our approach exploits the
diffraction properties of sound waves as they bend around a barrier or an
obstacle in the scene. We combine a ray tracing based sound propagation
algorithm with a Uniform Theory of Diffraction (UTD) model, which simulate
bending effects by placing a virtual sound source on a wedge in the
environment. We precompute the wedges of a reconstructed mesh of an indoor
scene and use them to generate diffraction acoustic rays to localize the 3D
position of the source. Our method identifies the convergence region of those
generated acoustic rays as the estimated source position based on a particle
filter. We have evaluated our algorithm in multiple scenarios consisting of a
static and dynamic NLOS sound source. In our tested cases, our approach can
localize a source position with an average accuracy error, 0.7m, measured by
the L2 distance between estimated and actual source locations in a 7m*7m*3m
room. Furthermore, we observe 37% to 130% improvement in accuracy over a
state-of-the-art localization method that does not model diffraction effects,
especially when a sound source is not visible to the robot.
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28 | Jacob's ladders, crossbreeding in the set of $ζ$-factorization formulas and selection of families of $ζ$-kindred real continuous functions | In this paper we introduce the notion of $\zeta$-crossbreeding in a set of
$\zeta$-factorization formulas and also the notion of complete hybrid formula
as the final result of that crossbreeding. The last formula is used as a
criterion for selection of families of $\zeta$-kindred elements in class of
real continuous functions.
Dedicated to recalling of Gregory Mendel's pea-crossbreeding.
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29 | Minimax Estimation of the $L_1$ Distance | We consider the problem of estimating the $L_1$ distance between two discrete
probability measures $P$ and $Q$ from empirical data in a nonasymptotic and
large alphabet setting. When $Q$ is known and one obtains $n$ samples from $P$,
we show that for every $Q$, the minimax rate-optimal estimator with $n$ samples
achieves performance comparable to that of the maximum likelihood estimator
(MLE) with $n\ln n$ samples. When both $P$ and $Q$ are unknown, we construct
minimax rate-optimal estimators whose worst case performance is essentially
that of the known $Q$ case with $Q$ being uniform, implying that $Q$ being
uniform is essentially the most difficult case. The \emph{effective sample size
enlargement} phenomenon, identified in Jiao \emph{et al.} (2015), holds both in
the known $Q$ case for every $Q$ and the $Q$ unknown case. However, the
construction of optimal estimators for $\|P-Q\|_1$ requires new techniques and
insights beyond the approximation-based method of functional estimation in Jiao
\emph{et al.} (2015).
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30 | Density large deviations for multidimensional stochastic hyperbolic conservation laws | We investigate the density large deviation function for a multidimensional
conservation law in the vanishing viscosity limit, when the probability
concentrates on weak solutions of a hyperbolic conservation law conservation
law. When the conductivity and dif-fusivity matrices are proportional, i.e. an
Einstein-like relation is satisfied, the problem has been solved in [4]. When
this proportionality does not hold, we compute explicitly the large deviation
function for a step-like density profile, and we show that the associated
optimal current has a non trivial structure. We also derive a lower bound for
the large deviation function, valid for a general weak solution, and leave the
general large deviation function upper bound as a conjecture.
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31 | mixup: Beyond Empirical Risk Minimization | Large deep neural networks are powerful, but exhibit undesirable behaviors
such as memorization and sensitivity to adversarial examples. In this work, we
propose mixup, a simple learning principle to alleviate these issues. In
essence, mixup trains a neural network on convex combinations of pairs of
examples and their labels. By doing so, mixup regularizes the neural network to
favor simple linear behavior in-between training examples. Our experiments on
the ImageNet-2012, CIFAR-10, CIFAR-100, Google commands and UCI datasets show
that mixup improves the generalization of state-of-the-art neural network
architectures. We also find that mixup reduces the memorization of corrupt
labels, increases the robustness to adversarial examples, and stabilizes the
training of generative adversarial networks.
| 1 | 0 | 0 | 1 | 0 | 0 |
32 | Equality of the usual definitions of Brakke flow | In 1978 Brakke introduced the mean curvature flow in the setting of geometric
measure theory. There exist multiple variants of the original definition. Here
we prove that most of them are indeed equal. One central point is to correct
the proof of Brakke's §3.5, where he develops an estimate for the evolution
of the measure of time-dependent test functions.
| 0 | 0 | 1 | 0 | 0 | 0 |
33 | Dynamic Base Station Repositioning to Improve Spectral Efficiency of Drone Small Cells | With recent advancements in drone technology, researchers are now considering
the possibility of deploying small cells served by base stations mounted on
flying drones. A major advantage of such drone small cells is that the
operators can quickly provide cellular services in areas of urgent demand
without having to pre-install any infrastructure. Since the base station is
attached to the drone, technically it is feasible for the base station to
dynamic reposition itself in response to the changing locations of users for
reducing the communication distance, decreasing the probability of signal
blocking, and ultimately increasing the spectral efficiency. In this paper, we
first propose distributed algorithms for autonomous control of drone movements,
and then model and analyse the spectral efficiency performance of a drone small
cell to shed new light on the fundamental benefits of dynamic repositioning. We
show that, with dynamic repositioning, the spectral efficiency of drone small
cells can be increased by nearly 100\% for realistic drone speed, height, and
user traffic model and without incurring any major increase in drone energy
consumption.
| 1 | 0 | 0 | 0 | 0 | 0 |
34 | An Unsupervised Homogenization Pipeline for Clustering Similar Patients using Electronic Health Record Data | Electronic health records (EHR) contain a large variety of information on the
clinical history of patients such as vital signs, demographics, diagnostic
codes and imaging data. The enormous potential for discovery in this rich
dataset is hampered by its complexity and heterogeneity.
We present the first study to assess unsupervised homogenization pipelines
designed for EHR clustering. To identify the optimal pipeline, we tested
accuracy on simulated data with varying amounts of redundancy, heterogeneity,
and missingness. We identified two optimal pipelines: 1) Multiple Imputation by
Chained Equations (MICE) combined with Local Linear Embedding; and 2) MICE,
Z-scoring, and Deep Autoencoders.
| 0 | 0 | 0 | 0 | 1 | 0 |
35 | Deep Neural Network Optimized to Resistive Memory with Nonlinear Current-Voltage Characteristics | Artificial Neural Network computation relies on intensive vector-matrix
multiplications. Recently, the emerging nonvolatile memory (NVM) crossbar array
showed a feasibility of implementing such operations with high energy
efficiency, thus there are many works on efficiently utilizing emerging NVM
crossbar array as analog vector-matrix multiplier. However, its nonlinear I-V
characteristics restrain critical design parameters, such as the read voltage
and weight range, resulting in substantial accuracy loss. In this paper,
instead of optimizing hardware parameters to a given neural network, we propose
a methodology of reconstructing a neural network itself optimized to resistive
memory crossbar arrays. To verify the validity of the proposed method, we
simulated various neural network with MNIST and CIFAR-10 dataset using two
different specific Resistive Random Access Memory (RRAM) model. Simulation
results show that our proposed neural network produces significantly higher
inference accuracies than conventional neural network when the synapse devices
have nonlinear I-V characteristics.
| 1 | 0 | 0 | 0 | 0 | 0 |
36 | Rate-Distortion Region of a Gray-Wyner Model with Side Information | In this work, we establish a full single-letter characterization of the
rate-distortion region of an instance of the Gray-Wyner model with side
information at the decoders. Specifically, in this model an encoder observes a
pair of memoryless, arbitrarily correlated, sources $(S^n_1,S^n_2)$ and
communicates with two receivers over an error-free rate-limited link of
capacity $R_0$, as well as error-free rate-limited individual links of
capacities $R_1$ to the first receiver and $R_2$ to the second receiver. Both
receivers reproduce the source component $S^n_2$ losslessly; and Receiver $1$
also reproduces the source component $S^n_1$ lossily, to within some prescribed
fidelity level $D_1$. Also, Receiver $1$ and Receiver $2$ are equipped
respectively with memoryless side information sequences $Y^n_1$ and $Y^n_2$.
Important in this setup, the side information sequences are arbitrarily
correlated among them, and with the source pair $(S^n_1,S^n_2)$; and are not
assumed to exhibit any particular ordering. Furthermore, by specializing the
main result to two Heegard-Berger models with successive refinement and
scalable coding, we shed light on the roles of the common and private
descriptions that the encoder should produce and what they should carry
optimally. We develop intuitions by analyzing the developed single-letter
optimal rate-distortion regions of these models, and discuss some insightful
binary examples.
| 1 | 0 | 1 | 0 | 0 | 0 |
37 | Fourier-based numerical approximation of the Weertman equation for moving dislocations | This work discusses the numerical approximation of a nonlinear
reaction-advection-diffusion equation, which is a dimensionless form of the
Weertman equation. This equation models steadily-moving dislocations in
materials science. It reduces to the celebrated Peierls-Nabarro equation when
its advection term is set to zero. The approach rests on considering a
time-dependent formulation, which admits the equation under study as its
long-time limit. Introducing a Preconditioned Collocation Scheme based on
Fourier transforms, the iterative numerical method presented solves the
time-dependent problem, delivering at convergence the desired numerical
solution to the Weertman equation. Although it rests on an explicit
time-evolution scheme, the method allows for large time steps, and captures the
solution in a robust manner. Numerical results illustrate the efficiency of the
approach for several types of nonlinearities.
| 0 | 1 | 0 | 0 | 0 | 0 |
38 | Design Decisions for Weave: A Real-Time Web-based Collaborative Visualization Framework | There are many web-based visualization systems available to date, each having
its strengths and limitations. The goals these systems set out to accomplish
influence design decisions and determine how reusable and scalable they are.
Weave is a new web-based visualization platform with the broad goal of enabling
visualization of any available data by anyone for any purpose. Our open source
framework supports highly interactive linked visualizations for users of
varying skill levels. What sets Weave apart from other systems is its
consideration for real-time remote collaboration with session history. We
provide a detailed account of the various framework designs we considered with
comparisons to existing state-of-the-art systems.
| 1 | 0 | 0 | 0 | 0 | 0 |
39 | Suzaku Analysis of the Supernova Remnant G306.3-0.9 and the Gamma-ray View of Its Neighborhood | We present an investigation of the supernova remnant (SNR) G306.3$-$0.9 using
archival multi-wavelength data. The Suzaku spectra are well described by
two-component thermal plasma models: The soft component is in ionization
equilibrium and has a temperature $\sim$0.59 keV, while the hard component has
temperature $\sim$3.2 keV and ionization time-scale $\sim$$2.6\times10^{10}$
cm$^{-3}$ s. We clearly detected Fe K-shell line at energy of $\sim$6.5 keV
from this remnant. The overabundances of Si, S, Ar, Ca, and Fe confirm that the
X-ray emission has an ejecta origin. The centroid energy of the Fe-K line
supports that G306.3$-$0.9 is a remnant of a Type Ia supernova (SN) rather than
a core-collapse SN. The GeV gamma-ray emission from G306.3$-$0.9 and its
surrounding were analyzed using about 6 years of Fermi data. We report about
the non-detection of G306.3$-$0.9 and the detection of a new extended gamma-ray
source in the south-west of G306.3$-$0.9 with a significance of
$\sim$13$\sigma$. We discuss several scenarios for these results with the help
of data from other wavebands to understand the SNR and its neighborhood.
| 0 | 1 | 0 | 0 | 0 | 0 |
40 | Japanese Sentiment Classification using a Tree-Structured Long Short-Term Memory with Attention | Previous approaches to training syntax-based sentiment classification models
required phrase-level annotated corpora, which are not readily available in
many languages other than English. Thus, we propose the use of tree-structured
Long Short-Term Memory with an attention mechanism that pays attention to each
subtree of the parse tree. Experimental results indicate that our model
achieves the state-of-the-art performance in a Japanese sentiment
classification task.
| 1 | 0 | 0 | 0 | 0 | 0 |
41 | Covariances, Robustness, and Variational Bayes | Mean-field Variational Bayes (MFVB) is an approximate Bayesian posterior
inference technique that is increasingly popular due to its fast runtimes on
large-scale datasets. However, even when MFVB provides accurate posterior means
for certain parameters, it often mis-estimates variances and covariances.
Furthermore, prior robustness measures have remained undeveloped for MFVB. By
deriving a simple formula for the effect of infinitesimal model perturbations
on MFVB posterior means, we provide both improved covariance estimates and
local robustness measures for MFVB, thus greatly expanding the practical
usefulness of MFVB posterior approximations. The estimates for MFVB posterior
covariances rely on a result from the classical Bayesian robustness literature
relating derivatives of posterior expectations to posterior covariances and
include the Laplace approximation as a special case. Our key condition is that
the MFVB approximation provides good estimates of a select subset of posterior
means---an assumption that has been shown to hold in many practical settings.
In our experiments, we demonstrate that our methods are simple, general, and
fast, providing accurate posterior uncertainty estimates and robustness
measures with runtimes that can be an order of magnitude faster than MCMC.
| 0 | 0 | 0 | 1 | 0 | 0 |
42 | Are multi-factor Gaussian term structure models still useful? An empirical analysis on Italian BTPs | In this paper, we empirically study models for pricing Italian sovereign
bonds under a reduced form framework, by assuming different dynamics for the
short-rate process. We analyze classical Cox-Ingersoll-Ross and Vasicek
multi-factor models, with a focus on optimization algorithms applied in the
calibration exercise. The Kalman filter algorithm together with a maximum
likelihood estimation method are considered to fit the Italian term-structure
over a 12-year horizon, including the global financial crisis and the euro area
sovereign debt crisis. Analytic formulas for the gradient vector and the
Hessian matrix of the likelihood function are provided.
| 0 | 0 | 0 | 0 | 0 | 1 |
43 | Probing valley filtering effect by Andreev reflection in zigzag graphene nanoribbon | Ballistic point contact (BPC) with zigzag edges in graphene is a main
candidate of a valley filter, in which the polarization of the valley degree of
freedom can be selected by using a local gate voltage. Here, we propose to
detect the valley filtering effect by Andreev reflection. Because electrons in
the lowest conduction band and the highest valence band of the BPC possess
opposite chirality, the inter-band Andreev reflection is strongly suppressed,
after multiple scattering and interference. We draw this conclusion by both the
scattering matrix analysis and the numerical simulation. The Andreev reflection
as a function of the incident energy of electrons and the local gate voltage at
the BPC is obtained, by which the parameter region for a perfect valley filter
and the direction of valley polarization can be determined. The Andreev
reflection exhibits an oscillatory decay with the length of the BPC, indicating
a negative correlation to valley polarization.
| 0 | 1 | 0 | 0 | 0 | 0 |
44 | Generalized Approximate Message-Passing Decoder for Universal Sparse Superposition Codes | Sparse superposition (SS) codes were originally proposed as a
capacity-achieving communication scheme over the additive white Gaussian noise
channel (AWGNC) [1]. Very recently, it was discovered that these codes are
universal, in the sense that they achieve capacity over any memoryless channel
under generalized approximate message-passing (GAMP) decoding [2], although
this decoder has never been stated for SS codes. In this contribution we
introduce the GAMP decoder for SS codes, we confirm empirically the
universality of this communication scheme through its study on various channels
and we provide the main analysis tools: state evolution and potential. We also
compare the performance of GAMP with the Bayes-optimal MMSE decoder. We
empirically illustrate that despite the presence of a phase transition
preventing GAMP to reach the optimal performance, spatial coupling allows to
boost the performance that eventually tends to capacity in a proper limit. We
also prove that, in contrast with the AWGNC case, SS codes for binary input
channels have a vanishing error floor in the limit of large codewords.
Moreover, the performance of Hadamard-based encoders is assessed for practical
implementations.
| 1 | 0 | 1 | 0 | 0 | 0 |
45 | LAAIR: A Layered Architecture for Autonomous Interactive Robots | When developing general purpose robots, the overarching software architecture
can greatly affect the ease of accomplishing various tasks. Initial efforts to
create unified robot systems in the 1990s led to hybrid architectures,
emphasizing a hierarchy in which deliberative plans direct the use of reactive
skills. However, since that time there has been significant progress in the
low-level skills available to robots, including manipulation and perception,
making it newly feasible to accomplish many more tasks in real-world domains.
There is thus renewed optimism that robots will be able to perform a wide array
of tasks while maintaining responsiveness to human operators. However, the top
layer in traditional hybrid architectures, designed to achieve long-term goals,
can make it difficult to react quickly to human interactions during goal-driven
execution. To mitigate this difficulty, we propose a novel architecture that
supports such transitions by adding a top-level reactive module which has
flexible access to both reactive skills and a deliberative control module. To
validate this architecture, we present a case study of its application on a
domestic service robot platform.
| 1 | 0 | 0 | 0 | 0 | 0 |
46 | 3D Human Pose Estimation in RGBD Images for Robotic Task Learning | We propose an approach to estimate 3D human pose in real world units from a
single RGBD image and show that it exceeds performance of monocular 3D pose
estimation approaches from color as well as pose estimation exclusively from
depth. Our approach builds on robust human keypoint detectors for color images
and incorporates depth for lifting into 3D. We combine the system with our
learning from demonstration framework to instruct a service robot without the
need of markers. Experiments in real world settings demonstrate that our
approach enables a PR2 robot to imitate manipulation actions observed from a
human teacher.
| 1 | 0 | 0 | 0 | 0 | 0 |
47 | Simultaneous non-vanishing for Dirichlet L-functions | We extend the work of Fouvry, Kowalski and Michel on correlation between
Hecke eigenvalues of modular forms and algebraic trace functions in order to
establish an asymptotic formula for a generalized cubic moment of modular
L-functions at the central point s = 1/2 and for prime moduli q. As an
application, we exploit our recent result on the mollification of the fourth
moment of Dirichlet L-functions to derive that for any pair
$(\omega_1,\omega_2)$ of multiplicative characters modulo q, there is a
positive proportion of $\chi$ (mod q) such that $L(\chi, 1/2 ), L(\chi\omega_1,
1/2 )$ and $L(\chi\omega_2, 1/2)$ are simultaneously not too small.
| 0 | 0 | 1 | 0 | 0 | 0 |
48 | Wehrl Entropy Based Quantification of Nonclassicality for Single Mode Quantum Optical States | Nonclassical states of a quantized light are described in terms of
Glauber-Sudarshan P distribution which is not a genuine classical probability
distribution. Despite several attempts, defining a uniform measure of
nonclassicality (NC) for the single mode quantum states of light is yet an open
task. In our previous work [Phys. Rev. A 95, 012330 (2017)] we have shown that
the existing well-known measures fail to quantify the NC of single mode states
that are generated under multiple NC-inducing operations. Recently, Ivan et.
al. [Quantum. Inf. Process. 11, 853 (2012)] have defined a measure of
non-Gaussian character of quantum optical states in terms of Wehrl entropy.
Here, we adopt this concept in the context of single mode NC. In this paper, we
propose a new quantification of NC for the single mode quantum states of light
as the difference between the total Wehrl entropy of the state and the maximum
Wehrl entropy arising due to its classical characteristics. This we achieve by
subtracting from its Wehrl entropy, the maximum Wehrl entropy attainable by any
classical state that has same randomness as measured in terms of von-Neumann
entropy. We obtain analytic expressions of NC for most of the states, in
particular, all pure states and Gaussian mixed states. However, the evaluation
of NC for the non-Gaussian mixed states is subject to extensive numerical
computation that lies beyond the scope of the current work. We show that, along
with the states generated under single NC-inducing operations, also for the
broader class of states that are generated under multiple NC-inducing
operations, our quantification enumerates the NC consistently.
| 1 | 1 | 0 | 0 | 0 | 0 |
49 | Attention-based Natural Language Person Retrieval | Following the recent progress in image classification and captioning using
deep learning, we develop a novel natural language person retrieval system
based on an attention mechanism. More specifically, given the description of a
person, the goal is to localize the person in an image. To this end, we first
construct a benchmark dataset for natural language person retrieval. To do so,
we generate bounding boxes for persons in a public image dataset from the
segmentation masks, which are then annotated with descriptions and attributes
using the Amazon Mechanical Turk. We then adopt a region proposal network in
Faster R-CNN as a candidate region generator. The cropped images based on the
region proposals as well as the whole images with attention weights are fed
into Convolutional Neural Networks for visual feature extraction, while the
natural language expression and attributes are input to Bidirectional Long
Short- Term Memory (BLSTM) models for text feature extraction. The visual and
text features are integrated to score region proposals, and the one with the
highest score is retrieved as the output of our system. The experimental
results show significant improvement over the state-of-the-art method for
generic object retrieval and this line of research promises to benefit search
in surveillance video footage.
| 1 | 0 | 0 | 0 | 0 | 0 |
50 | Large Scale Automated Forecasting for Monitoring Network Safety and Security | Real time large scale streaming data pose major challenges to forecasting, in
particular defying the presence of human experts to perform the corresponding
analysis. We present here a class of models and methods used to develop an
automated, scalable and versatile system for large scale forecasting oriented
towards safety and security monitoring. Our system provides short and long term
forecasts and uses them to detect safety and security issues in relation with
multiple internet connected devices well in advance they might take place.
| 0 | 0 | 0 | 1 | 0 | 0 |
51 | Contextual Regression: An Accurate and Conveniently Interpretable Nonlinear Model for Mining Discovery from Scientific Data | Machine learning algorithms such as linear regression, SVM and neural network
have played an increasingly important role in the process of scientific
discovery. However, none of them is both interpretable and accurate on
nonlinear datasets. Here we present contextual regression, a method that joins
these two desirable properties together using a hybrid architecture of neural
network embedding and dot product layer. We demonstrate its high prediction
accuracy and sensitivity through the task of predictive feature selection on a
simulated dataset and the application of predicting open chromatin sites in the
human genome. On the simulated data, our method achieved high fidelity recovery
of feature contributions under random noise levels up to 200%. On the open
chromatin dataset, the application of our method not only outperformed the
state of the art method in terms of accuracy, but also unveiled two previously
unfound open chromatin related histone marks. Our method can fill the blank of
accurate and interpretable nonlinear modeling in scientific data mining tasks.
| 1 | 0 | 0 | 1 | 0 | 0 |
52 | Multi-time correlators in continuous measurement of qubit observables | We consider multi-time correlators for output signals from linear detectors,
continuously measuring several qubit observables at the same time. Using the
quantum Bayesian formalism, we show that for unital (symmetric) evolution in
the absence of phase backaction, an $N$-time correlator can be expressed as a
product of two-time correlators when $N$ is even. For odd $N$, there is a
similar factorization, which also includes a single-time average. Theoretical
predictions agree well with experimental results for two detectors, which
simultaneously measure non-commuting qubit observables.
| 0 | 1 | 0 | 0 | 0 | 0 |
53 | Parallelism, Concurrency and Distribution in Constraint Handling Rules: A Survey | Constraint Handling Rules is an effective concurrent declarative programming
language and a versatile computational logic formalism. CHR programs consist of
guarded reactive rules that transform multisets of constraints. One of the main
features of CHR is its inherent concurrency. Intuitively, rules can be applied
to parts of a multiset in parallel. In this comprehensive survey, we give an
overview of concurrent and parallel as well as distributed CHR semantics,
standard and more exotic, that have been proposed over the years at various
levels of refinement. These semantics range from the abstract to the concrete.
They are related by formal soundness results. Their correctness is established
as correspondence between parallel and sequential computations. We present
common concise sample CHR programs that have been widely used in experiments
and benchmarks. We review parallel CHR implementations in software and
hardware. The experimental results obtained show a consistent parallel speedup.
Most implementations are available online. The CHR formalism can also be used
to implement and reason with models for concurrency. To this end, the Software
Transaction Model, the Actor Model, Colored Petri Nets and the Join-Calculus
have been faithfully encoded in CHR. Under consideration in Theory and Practice
of Logic Programming (TPLP).
| 1 | 0 | 0 | 0 | 0 | 0 |
54 | Robustness against the channel effect in pathological voice detection | Many people are suffering from voice disorders, which can adversely affect
the quality of their lives. In response, some researchers have proposed
algorithms for automatic assessment of these disorders, based on voice signals.
However, these signals can be sensitive to the recording devices. Indeed, the
channel effect is a pervasive problem in machine learning for healthcare. In
this study, we propose a detection system for pathological voice, which is
robust against the channel effect. This system is based on a bidirectional LSTM
network. To increase the performance robustness against channel mismatch, we
integrate domain adversarial training (DAT) to eliminate the differences
between the devices. When we train on data recorded on a high-quality
microphone and evaluate on smartphone data without labels, our robust detection
system increases the PR-AUC from 0.8448 to 0.9455 (and 0.9522 with target
sample labels). To the best of our knowledge, this is the first study applying
unsupervised domain adaptation to pathological voice detection. Notably, our
system does not need target device sample labels, which allows for
generalization to many new devices.
| 1 | 0 | 0 | 0 | 0 | 0 |
55 | An Effective Framework for Constructing Exponent Lattice Basis of Nonzero Algebraic Numbers | Computing a basis for the exponent lattice of algebraic numbers is a basic
problem in the field of computational number theory with applications to many
other areas. The main cost of a well-known algorithm
\cite{ge1993algorithms,kauers2005algorithms} solving the problem is on
computing the primitive element of the extended field generated by the given
algebraic numbers. When the extended field is of large degree, the problem
seems intractable by the tool implementing the algorithm. In this paper, a
special kind of exponent lattice basis is introduced. An important feature of
the basis is that it can be inductively constructed, which allows us to deal
with the given algebraic numbers one by one when computing the basis. Based on
this, an effective framework for constructing exponent lattice basis is
proposed. Through computing a so-called pre-basis first and then solving some
linear Diophantine equations, the basis can be efficiently constructed. A new
certificate for multiplicative independence and some techniques for decreasing
degrees of algebraic numbers are provided to speed up the computation. The new
algorithm has been implemented with Mathematica and its effectiveness is
verified by testing various examples. Moreover, the algorithm is applied to
program verification for finding invariants of linear loops.
| 1 | 0 | 0 | 0 | 0 | 0 |
56 | Competing evolutionary paths in growing populations with applications to multidrug resistance | Investigating the emergence of a particular cell type is a recurring theme in
models of growing cellular populations. The evolution of resistance to therapy
is a classic example. Common questions are: when does the cell type first
occur, and via which sequence of steps is it most likely to emerge? For growing
populations, these questions can be formulated in a general framework of
branching processes spreading through a graph from a root to a target vertex.
Cells have a particular fitness value on each vertex and can transition along
edges at specific rates. Vertices represents cell states, say \mic{genotypes
}or physical locations, while possible transitions are acquiring a mutation or
cell migration. We focus on the setting where cells at the root vertex have the
highest fitness and transition rates are small. Simple formulas are derived for
the time to reach the target vertex and for the probability that it is reached
along a given path in the graph. We demonstrate our results on \mic{several
scenarios relevant to the emergence of drug resistance}, including: the
orderings of resistance-conferring mutations in bacteria and the impact of
imperfect drug penetration in cancer.
| 0 | 0 | 0 | 0 | 1 | 0 |
57 | Transient flows in active porous media | Stimuli-responsive materials that modify their shape in response to changes
in environmental conditions -- such as solute concentration, temperature, pH,
and stress -- are widespread in nature and technology. Applications include
micro- and nanoporous materials used in filtration and flow control. The
physiochemical mechanisms that induce internal volume modifications have been
widely studies. The coupling between induced volume changes and solute
transport through porous materials, however, is not well understood. Here, we
consider advective and diffusive transport through a small channel linking two
large reservoirs. A section of stimulus-responsive material regulates the
channel permeability, which is a function of the local solute concentration. We
derive an exact solution to the coupled transport problem and demonstrate the
existence of a flow regime in which the steady state is reached via a damped
oscillation around the equilibrium concentration value. Finally, the
feasibility of an experimental observation of the phenomena is discussed.
Please note that this version of the paper has not been formally peer reviewed,
revised or accepted by a journal.
| 0 | 1 | 0 | 0 | 0 | 0 |
58 | An information model for modular robots: the Hardware Robot Information Model (HRIM) | Today's landscape of robotics is dominated by vertical integration where
single vendors develop the final product leading to slow progress, expensive
products and customer lock-in. Opposite to this, an horizontal integration
would result in a rapid development of cost-effective mass-market products with
an additional consumer empowerment. The transition of an industry from vertical
integration to horizontal integration is typically catalysed by de facto
industry standards that enable a simplified and seamless integration of
products. However, in robotics there is currently no leading candidate for a
global plug-and-play standard.
This paper tackles the problem of incompatibility between robot components
that hinder the reconfigurability and flexibility demanded by the robotics
industry. Particularly, it presents a model to create plug-and-play robot
hardware components. Rather than iteratively evolving previous ontologies, our
proposed model answers the needs identified by the industry while facilitating
interoperability, measurability and comparability of robotics technology. Our
approach differs significantly with the ones presented before as it is
hardware-oriented and establishes a clear set of actions towards the
integration of this model in real environments and with real manufacturers.
| 1 | 0 | 0 | 0 | 0 | 0 |
59 | Detecting Adversarial Samples Using Density Ratio Estimates | Machine learning models, especially based on deep architectures are used in
everyday applications ranging from self driving cars to medical diagnostics. It
has been shown that such models are dangerously susceptible to adversarial
samples, indistinguishable from real samples to human eye, adversarial samples
lead to incorrect classifications with high confidence. Impact of adversarial
samples is far-reaching and their efficient detection remains an open problem.
We propose to use direct density ratio estimation as an efficient model
agnostic measure to detect adversarial samples. Our proposed method works
equally well with single and multi-channel samples, and with different
adversarial sample generation methods. We also propose a method to use density
ratio estimates for generating adversarial samples with an added constraint of
preserving density ratio.
| 1 | 0 | 0 | 1 | 0 | 0 |
60 | The Query Complexity of Cake Cutting | We study the query complexity of cake cutting and give lower and upper bounds
for computing approximately envy-free, perfect, and equitable allocations with
the minimum number of cuts. The lower bounds are tight for computing connected
envy-free allocations among n=3 players and for computing perfect and equitable
allocations with minimum number of cuts between n=2 players.
We also formalize moving knife procedures and show that a large subclass of
this family, which captures all the known moving knife procedures, can be
simulated efficiently with arbitrarily small error in the Robertson-Webb query
model.
| 1 | 0 | 0 | 0 | 0 | 0 |
61 | Stacked Convolutional and Recurrent Neural Networks for Music Emotion Recognition | This paper studies the emotion recognition from musical tracks in the
2-dimensional valence-arousal (V-A) emotional space. We propose a method based
on convolutional (CNN) and recurrent neural networks (RNN), having
significantly fewer parameters compared with the state-of-the-art method for
the same task. We utilize one CNN layer followed by two branches of RNNs
trained separately for arousal and valence. The method was evaluated using the
'MediaEval2015 emotion in music' dataset. We achieved an RMSE of 0.202 for
arousal and 0.268 for valence, which is the best result reported on this
dataset.
| 1 | 0 | 0 | 0 | 0 | 0 |
62 | Timed Automata with Polynomial Delay and their Expressiveness | We consider previous models of Timed, Probabilistic and Stochastic Timed
Automata, we introduce our model of Timed Automata with Polynomial Delay and we
characterize the expressiveness of these models relative to each other.
| 1 | 0 | 0 | 0 | 0 | 0 |
63 | Superconducting properties of Cu intercalated Bi$_2$Se$_3$ studied by Muon Spin Spectroscopy | We present muon spin rotation measurements on superconducting Cu intercalated
Bi$_2$Se$_3$, which was suggested as a realization of a topological
superconductor. We observe a clear evidence of the superconducting transition
below 4 K, where the width of magnetic field distribution increases as the
temperature is decreased. The measured broadening at mK temperatures suggests a
large London penetration depth in the $ab$ plane ($\lambda_{\mathrm{eff}}\sim
1.6$ $\mathrm{\mu}$m). We show that the temperature dependence of this
broadening follows the BCS prediction, but could be consistent with several gap
symmetries.
| 0 | 1 | 0 | 0 | 0 | 0 |
64 | Time-domain THz spectroscopy reveals coupled protein-hydration dielectric response in solutions of native and fibrils of human lyso-zyme | Here we reveal details of the interaction between human lysozyme proteins,
both native and fibrils, and their water environment by intense terahertz time
domain spectroscopy. With the aid of a rigorous dielectric model, we determine
the amplitude and phase of the oscillating dipole induced by the THz field in
the volume containing the protein and its hydration water. At low
concentrations, the amplitude of this induced dipolar response decreases with
increasing concentration. Beyond a certain threshold, marking the onset of the
interactions between the extended hydration shells, the amplitude remains fixed
but the phase of the induced dipolar response, which is initially in phase with
the applied THz field, begins to change. The changes observed in the THz
response reveal protein-protein interactions me-diated by extended hydration
layers, which may control fibril formation and may have an important role in
chemical recognition phenomena.
| 0 | 1 | 0 | 0 | 0 | 0 |
65 | Inversion of Qubit Energy Levels in Qubit-Oscillator Circuits in the Deep-Strong-Coupling Regime | We report on experimentally measured light shifts of superconducting flux
qubits deep-strongly coupled to LC oscillators, where the coupling constants
are comparable to the qubit and oscillator resonance frequencies. By using
two-tone spectroscopy, the energies of the six lowest levels of each circuit
are determined. We find huge Lamb shifts that exceed 90% of the bare qubit
frequencies and inversions of the qubits' ground and excited states when there
are a finite number of photons in the oscillator. Our experimental results
agree with theoretical predictions based on the quantum Rabi model.
| 0 | 1 | 0 | 0 | 0 | 0 |
66 | Deep Multiple Instance Feature Learning via Variational Autoencoder | We describe a novel weakly supervised deep learning framework that combines
both the discriminative and generative models to learn meaningful
representation in the multiple instance learning (MIL) setting. MIL is a weakly
supervised learning problem where labels are associated with groups of
instances (referred as bags) instead of individual instances. To address the
essential challenge in MIL problems raised from the uncertainty of positive
instances label, we use a discriminative model regularized by variational
autoencoders (VAEs) to maximize the differences between latent representations
of all instances and negative instances. As a result, the hidden layer of the
variational autoencoder learns meaningful representation. This representation
can effectively be used for MIL problems as illustrated by better performance
on the standard benchmark datasets comparing to the state-of-the-art
approaches. More importantly, unlike most related studies, the proposed
framework can be easily scaled to large dataset problems, as illustrated by the
audio event detection and segmentation task. Visualization also confirms the
effectiveness of the latent representation in discriminating positive and
negative classes.
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67 | Regularity of envelopes in Kähler classes | We establish the C^{1,1} regularity of quasi-psh envelopes in a Kahler class,
confirming a conjecture of Berman.
| 0 | 0 | 1 | 0 | 0 | 0 |
68 | $S^1$-equivariant Index theorems and Morse inequalities on complex manifolds with boundary | Let $M$ be a complex manifold of dimension $n$ with smooth connected boundary
$X$. Assume that $\overline M$ admits a holomorphic $S^1$-action preserving the
boundary $X$ and the $S^1$-action is transversal and CR on $X$. We show that
the $\overline\partial$-Neumann Laplacian on $M$ is transversally elliptic and
as a consequence, the $m$-th Fourier component of the $q$-th Dolbeault
cohomology group $H^q_m(\overline M)$ is finite dimensional, for every
$m\in\mathbb Z$ and every $q=0,1,\ldots,n$. This enables us to define
$\sum^{n}_{j=0}(-1)^j{\rm dim\,}H^q_m(\overline M)$ the $m$-th Fourier
component of the Euler characteristic on $M$ and to study large $m$-behavior of
$H^q_m(\overline M)$. In this paper, we establish an index formula for
$\sum^{n}_{j=0}(-1)^j{\rm dim\,}H^q_m(\overline M)$ and Morse inequalities for
$H^q_m(\overline M)$.
| 0 | 0 | 1 | 0 | 0 | 0 |
69 | Internal Model from Observations for Reward Shaping | Reinforcement learning methods require careful design involving a reward
function to obtain the desired action policy for a given task. In the absence
of hand-crafted reward functions, prior work on the topic has proposed several
methods for reward estimation by using expert state trajectories and action
pairs. However, there are cases where complete or good action information
cannot be obtained from expert demonstrations. We propose a novel reinforcement
learning method in which the agent learns an internal model of observation on
the basis of expert-demonstrated state trajectories to estimate rewards without
completely learning the dynamics of the external environment from state-action
pairs. The internal model is obtained in the form of a predictive model for the
given expert state distribution. During reinforcement learning, the agent
predicts the reward as a function of the difference between the actual state
and the state predicted by the internal model. We conducted multiple
experiments in environments of varying complexity, including the Super Mario
Bros and Flappy Bird games. We show our method successfully trains good
policies directly from expert game-play videos.
| 1 | 0 | 0 | 1 | 0 | 0 |
70 | Characterizations of quasitrivial symmetric nondecreasing associative operations | In this paper we are interested in the class of n-ary operations on an
arbitrary chain that are quasitrivial, symmetric, nondecreasing, and
associative. We first provide a description of these operations. We then prove
that associativity can be replaced with bisymmetry in the definition of this
class. Finally we investigate the special situation where the chain is finite.
| 0 | 0 | 1 | 0 | 0 | 0 |
71 | Multivariate Dependency Measure based on Copula and Gaussian Kernel | We propose a new multivariate dependency measure. It is obtained by
considering a Gaussian kernel based distance between the copula transform of
the given d-dimensional distribution and the uniform copula and then
appropriately normalizing it. The resulting measure is shown to satisfy a
number of desirable properties. A nonparametric estimate is proposed for this
dependency measure and its properties (finite sample as well as asymptotic) are
derived. Some comparative studies of the proposed dependency measure estimate
with some widely used dependency measure estimates on artificial datasets are
included. A non-parametric test of independence between two or more random
variables based on this measure is proposed. A comparison of the proposed test
with some existing nonparametric multivariate test for independence is
presented.
| 0 | 0 | 1 | 1 | 0 | 0 |
72 | The nature of the tensor order in Cd2Re2O7 | The pyrochlore metal Cd2Re2O7 has been recently investigated by
second-harmonic generation (SHG) reflectivity. In this paper, we develop a
general formalism that allows for the identification of the relevant tensor
components of the SHG from azimuthal scans. We demonstrate that the secondary
order parameter identified by SHG at the structural phase transition is the
x2-y2 component of the axial toroidal quadrupole. This differs from the 3z2-r2
symmetry of the atomic displacements associated with the I-4m2 crystal
structure that was previously thought to be its origin. Within the same
formalism, we suggest that the primary order parameter detected in the SHG
experiment is the 3z2-r2 component of the magnetic quadrupole. We discuss the
general mechanism driving the phase transition in our proposed framework, and
suggest experiments, particularly resonant X-ray scattering ones, that could
clarify this issue.
| 0 | 1 | 0 | 0 | 0 | 0 |
73 | Efficient and consistent inference of ancestral sequences in an evolutionary model with insertions and deletions under dense taxon sampling | In evolutionary biology, the speciation history of living organisms is
represented graphically by a phylogeny, that is, a rooted tree whose leaves
correspond to current species and branchings indicate past speciation events.
Phylogenies are commonly estimated from molecular sequences, such as DNA
sequences, collected from the species of interest. At a high level, the idea
behind this inference is simple: the further apart in the Tree of Life are two
species, the greater is the number of mutations to have accumulated in their
genomes since their most recent common ancestor. In order to obtain accurate
estimates in phylogenetic analyses, it is standard practice to employ
statistical approaches based on stochastic models of sequence evolution on a
tree. For tractability, such models necessarily make simplifying assumptions
about the evolutionary mechanisms involved. In particular, commonly omitted are
insertions and deletions of nucleotides -- also known as indels.
Properly accounting for indels in statistical phylogenetic analyses remains a
major challenge in computational evolutionary biology. Here we consider the
problem of reconstructing ancestral sequences on a known phylogeny in a model
of sequence evolution incorporating nucleotide substitutions, insertions and
deletions, specifically the classical TKF91 process. We focus on the case of
dense phylogenies of bounded height, which we refer to as the taxon-rich
setting, where statistical consistency is achievable. We give the first
polynomial-time ancestral reconstruction algorithm with provable guarantees
under constant rates of mutation. Our algorithm succeeds when the phylogeny
satisfies the "big bang" condition, a necessary and sufficient condition for
statistical consistency in this context.
| 1 | 0 | 1 | 1 | 0 | 0 |
74 | Flow Characteristics and Cores of Complex Network and Multiplex Type Systems | Subject of research is complex networks and network systems. The network
system is defined as a complex network in which flows are moved. Classification
of flows in the network is carried out on the basis of ordering and continuity.
It is shown that complex networks with different types of flows generate
various network systems. Flow analogues of the basic concepts of the theory of
complex networks are introduced and the main problems of this theory in terms
of flow characteristics are formulated. Local and global flow characteristics
of networks bring closer the theory of complex networks to the systems theory
and systems analysis. Concept of flow core of network system is introduced and
defined how it simplifies the process of its investigation. Concepts of kernel
and flow core of multiplex are determined. Features of operation of multiplex
type systems are analyzed.
| 1 | 1 | 0 | 0 | 0 | 0 |
75 | Pattern-forming fronts in a Swift-Hohenberg equation with directional quenching - parallel and oblique stripes | We study the effect of domain growth on the orientation of striped phases in
a Swift-Hohenberg equation. Domain growth is encoded in a step-like parameter
dependence that allows stripe formation in a half plane, and suppresses
patterns in the complement, while the boundary of the pattern-forming region is
propagating with fixed normal velocity. We construct front solutions that leave
behind stripes in the pattern-forming region that are parallel to or at a small
oblique angle to the boundary.
Technically, the construction of stripe formation parallel to the boundary
relies on ill-posed, infinite-dimensional spatial dynamics. Stripes forming at
a small oblique angle are constructed using a functional-analytic, perturbative
approach. Here, the main difficulties are the presence of continuous spectrum
and the fact that small oblique angles appear as a singular perturbation in a
traveling-wave problem. We resolve the former difficulty using a farfield-core
decomposition and Fredholm theory in weighted spaces. The singular perturbation
problem is resolved using preconditioners and boot-strapping.
| 0 | 1 | 0 | 0 | 0 | 0 |
76 | Generalized Minimum Distance Estimators in Linear Regression with Dependent Errors | This paper discusses minimum distance estimation method in the linear
regression model with dependent errors which are strongly mixing. The
regression parameters are estimated through the minimum distance estimation
method, and asymptotic distributional properties of the estimators are
discussed. A simulation study compares the performance of the minimum distance
estimator with other well celebrated estimator. This simulation study shows the
superiority of the minimum distance estimator over another estimator. KoulMde
(R package) which was used for the simulation study is available online. See
section 4 for the detail.
| 0 | 0 | 1 | 1 | 0 | 0 |
77 | Live Service Migration in Mobile Edge Clouds | Mobile edge clouds (MECs) bring the benefits of the cloud closer to the user,
by installing small cloud infrastructures at the network edge. This enables a
new breed of real-time applications, such as instantaneous object recognition
and safety assistance in intelligent transportation systems, that require very
low latency. One key issue that comes with proximity is how to ensure that
users always receive good performance as they move across different locations.
Migrating services between MECs is seen as the means to achieve this. This
article presents a layered framework for migrating active service applications
that are encapsulated either in virtual machines (VMs) or containers. This
layering approach allows a substantial reduction in service downtime. The
framework is easy to implement using readily available technologies, and one of
its key advantages is that it supports containers, which is a promising
emerging technology that offers tangible benefits over VMs. The migration
performance of various real applications is evaluated by experiments under the
presented framework. Insights drawn from the experimentation results are
discussed.
| 1 | 0 | 0 | 0 | 0 | 0 |
78 | Induced density correlations in a sonic black hole condensate | Analog black/white hole pairs, consisting of a region of supersonic flow,
have been achieved in a recent experiment by J. Steinhauer using an elongated
Bose-Einstein condensate. A growing standing density wave, and a checkerboard
feature in the density-density correlation function, were observed in the
supersonic region. We model the density-density correlation function, taking
into account both quantum fluctuations and the shot-to-shot variation of atom
number normally present in ultracold-atom experiments. We find that quantum
fluctuations alone produce some, but not all, of the features of the
correlation function, whereas atom-number fluctuation alone can produce all the
observed features, and agreement is best when both are included. In both cases,
the density-density correlation is not intrinsic to the fluctuations, but
rather is induced by modulation of the standing wave caused by the
fluctuations.
| 0 | 1 | 0 | 0 | 0 | 0 |
79 | Genus growth in $\mathbb{Z}_p$-towers of function fields | Let $K$ be a function field over a finite field $k$ of characteristic $p$ and
let $K_{\infty}/K$ be a geometric extension with Galois group $\mathbb{Z}_p$.
Let $K_n$ be the corresponding subextension with Galois group
$\mathbb{Z}/p^n\mathbb{Z}$ and genus $g_n$. In this paper, we give a simple
explicit formula $g_n$ in terms of an explicit Witt vector construction of the
$\mathbb{Z}_p$-tower. This formula leads to a tight lower bound on $g_n$ which
is quadratic in $p^n$. Furthermore, we determine all $\mathbb{Z}_p$-towers for
which the genus sequence is stable, in the sense that there are $a,b,c \in
\mathbb{Q}$ such that $g_n=a p^{2n}+b p^n +c$ for $n$ large enough. Such genus
stable towers are expected to have strong stable arithmetic properties for
their zeta functions. A key technical contribution of this work is a new
simplified formula for the Schmid-Witt symbol coming from local class field
theory.
| 0 | 0 | 1 | 0 | 0 | 0 |
80 | Topological Phases emerging from Spin-Orbital Physics | We study the evolution of spin-orbital correlations in an inhomogeneous
quantum system with an impurity replacing a doublon by a holon orbital degree
of freedom. Spin-orbital entanglement is large when spin correlations are
antiferromagnetic, while for a ferromagnetic host we obtain a pure orbital
description. In this regime the orbital model can be mapped on spinless
fermions and we uncover topological phases with zero energy modes at the edge
or at the domain between magnetically inequivalent regions.
| 0 | 1 | 0 | 0 | 0 | 0 |
81 | Accurate and Diverse Sampling of Sequences based on a "Best of Many" Sample Objective | For autonomous agents to successfully operate in the real world, anticipation
of future events and states of their environment is a key competence. This
problem has been formalized as a sequence extrapolation problem, where a number
of observations are used to predict the sequence into the future. Real-world
scenarios demand a model of uncertainty of such predictions, as predictions
become increasingly uncertain -- in particular on long time horizons. While
impressive results have been shown on point estimates, scenarios that induce
multi-modal distributions over future sequences remain challenging. Our work
addresses these challenges in a Gaussian Latent Variable model for sequence
prediction. Our core contribution is a "Best of Many" sample objective that
leads to more accurate and more diverse predictions that better capture the
true variations in real-world sequence data. Beyond our analysis of improved
model fit, our models also empirically outperform prior work on three diverse
tasks ranging from traffic scenes to weather data.
| 0 | 0 | 0 | 1 | 0 | 0 |
82 | Exploring RNN-Transducer for Chinese Speech Recognition | End-to-end approaches have drawn much attention recently for significantly
simplifying the construction of an automatic speech recognition (ASR) system.
RNN transducer (RNN-T) is one of the popular end-to-end methods. Previous
studies have shown that RNN-T is difficult to train and a very complex training
process is needed for a reasonable performance. In this paper, we explore RNN-T
for a Chinese large vocabulary continuous speech recognition (LVCSR) task and
aim to simplify the training process while maintaining performance. First, a
new strategy of learning rate decay is proposed to accelerate the model
convergence. Second, we find that adding convolutional layers at the beginning
of the network and using ordered data can discard the pre-training process of
the encoder without loss of performance. Besides, we design experiments to find
a balance among the usage of GPU memory, training circle and model performance.
Finally, we achieve 16.9% character error rate (CER) on our test set which is
2% absolute improvement from a strong BLSTM CE system with language model
trained on the same text corpus.
| 1 | 0 | 0 | 0 | 0 | 0 |
83 | A Debt-Aware Learning Approach for Resource Adaptations in Cloud Elasticity Management | Elasticity is a cloud property that enables applications and its execution
systems to dynamically acquire and release shared computational resources on
demand. Moreover, it unfolds the advantage of economies of scale in the cloud
through a drop in the average costs of these shared resources. However, it is
still an open challenge to achieve a perfect match between resource demand and
provision in autonomous elasticity management. Resource adaptation decisions
essentially involve a trade-off between economics and performance, which
produces a gap between the ideal and actual resource provisioning. This gap, if
not properly managed, can negatively impact the aggregate utility of a cloud
customer in the long run. To address this limitation, we propose a technical
debt-aware learning approach for autonomous elasticity management based on a
reinforcement learning of elasticity debts in resource provisioning; the
adaptation pursues strategic decisions that trades off economics against
performance. We extend CloudSim and Burlap to evaluate our approach. The
evaluation shows that a reinforcement learning of technical debts in elasticity
obtains a higher utility for a cloud customer, while conforming expected levels
of performance.
| 1 | 0 | 0 | 0 | 0 | 0 |
84 | Semi-simplicial spaces | This is an exposition of homotopical results on the geometric realization of
semi-simplicial spaces. We then use these to derive basic foundational results
about classifying spaces of topological categories, possibly without units. The
topics considered include: fibrancy conditions on topological categories; the
effect on classifying spaces of freely adjoining units; approximate notions of
units; Quillen's Theorems A and B for non-unital topological categories; the
effect on classifying spaces of changing the topology on the space of objects;
the Group-Completion Theorem.
| 0 | 0 | 1 | 0 | 0 | 0 |
85 | Constraints, Lazy Constraints, or Propagators in ASP Solving: An Empirical Analysis | Answer Set Programming (ASP) is a well-established declarative paradigm. One
of the successes of ASP is the availability of efficient systems.
State-of-the-art systems are based on the ground+solve approach. In some
applications this approach is infeasible because the grounding of one or few
constraints is expensive. In this paper, we systematically compare alternative
strategies to avoid the instantiation of problematic constraints, that are
based on custom extensions of the solver. Results on real and synthetic
benchmarks highlight some strengths and weaknesses of the different strategies.
(Under consideration for acceptance in TPLP, ICLP 2017 Special Issue.)
| 1 | 0 | 0 | 0 | 0 | 0 |
86 | A Unified Approach to Nonlinear Transformation Materials | The advances in geometric approaches to optical devices due to transformation
optics has led to the development of cloaks, concentrators, and other devices.
It has also been shown that transformation optics can be used to gravitational
fields from general relativity. However, the technique is currently constrained
to linear devices, as a consistent approach to nonlinearity (including both the
case of a nonlinear background medium and a nonlinear transformation) remains
an open question. Here we show that nonlinearity can be incorporated into
transformation optics in a consistent way. We use this to illustrate a number
of novel effects, including cloaking an optical soliton, modeling nonlinear
solutions to Einstein's field equations, controlling transport in a Debye
solid, and developing a set of constitutive to relations for relativistic
cloaks in arbitrary nonlinear backgrounds.
| 0 | 1 | 0 | 0 | 0 | 0 |
87 | Stationary crack propagation in a two-dimensional visco-elastic network model | We investigate crack propagation in a simple two-dimensional visco-elastic
model and find a scaling regime in the relation between the propagation
velocity and energy release rate or fracture energy, together with lower and
upper bounds of the scaling regime. On the basis of our result, the existence
of the lower and upper bounds is expected to be universal or model-independent:
the present simple simulation model provides generic insight into the physics
of crack propagation, and the model will be a first step towards the
development of a more refined coarse-grained model. Relatively abrupt changes
of velocity are predicted near the lower and upper bounds for the scaling
regime and the positions of the bounds could be good markers for the
development of tough polymers, for which we provide simple views that could be
useful as guiding principles for toughening polymer-based materials.
| 0 | 1 | 0 | 0 | 0 | 0 |
88 | A note on the fundamental group of Kodaira fibrations | The fundamental group $\pi$ of a Kodaira fibration is, by definition, the
extension of a surface group $\Pi_b$ by another surface group $\Pi_g$, i.e. \[
1 \rightarrow \Pi_g \rightarrow \pi \rightarrow \Pi_b \rightarrow 1. \]
Conversely, we can inquire about what conditions need to be satisfied by a
group of that sort in order to be the fundamental group of a Kodaira fibration.
In this short note we collect some restriction on the image of the classifying
map $m \colon \Pi_b \to \Gamma_g$ in terms of the coinvariant homology of
$\Pi_g$. In particular, we observe that if $\pi$ is the fundamental group of a
Kodaira fibration with relative irregularity $g-s$, then $g \leq 1+ 6s$, and we
show that this effectively constrains the possible choices for $\pi$, namely
that there are group extensions as above that fail to satisfy this bound, hence
cannot be the fundamental group of a Kodaira fibration. In particular this
provides examples of symplectic $4$--manifolds that fail to admit a Kähler
structure for reasons that eschew the usual obstructions.
| 0 | 0 | 1 | 0 | 0 | 0 |
89 | Photo-Chemically Directed Self-Assembly of Carbon Nanotubes on Surfaces | Transistors incorporating single-wall carbon nanotubes (CNTs) as the channel
material are used in a variety of electronics applications. However, a
competitive CNT-based technology requires the precise placement of CNTs at
predefined locations of a substrate. One promising placement approach is to use
chemical recognition to bind CNTs from solution at the desired locations on a
surface. Producing the chemical pattern on the substrate is challenging. Here
we describe a one-step patterning approach based on a highly photosensitive
surface monolayer. The monolayer contains chromophopric group as light
sensitive body with heteroatoms as high quantum yield photolysis center. As
deposited, the layer will bind CNTs from solution. However, when exposed to
ultraviolet (UV) light with a low dose (60 mJ/cm2) similar to that used for
conventional photoresists, the monolayer cleaves and no longer binds CNTs.
These features allow standard, wafer-scale UV lithography processes to be used
to form a patterned chemical monolayer without the need for complex substrate
patterning or monolayer stamping.
| 0 | 1 | 0 | 0 | 0 | 0 |
90 | Split-and-augmented Gibbs sampler - Application to large-scale inference problems | This paper derives two new optimization-driven Monte Carlo algorithms
inspired from variable splitting and data augmentation. In particular, the
formulation of one of the proposed approaches is closely related to the
alternating direction method of multipliers (ADMM) main steps. The proposed
framework enables to derive faster and more efficient sampling schemes than the
current state-of-the-art methods and can embed the latter. By sampling
efficiently the parameter to infer as well as the hyperparameters of the
problem, the generated samples can be used to approximate Bayesian estimators
of the parameters to infer. Additionally, the proposed approach brings
confidence intervals at a low cost contrary to optimization methods.
Simulations on two often-studied signal processing problems illustrate the
performance of the two proposed samplers. All results are compared to those
obtained by recent state-of-the-art optimization and MCMC algorithms used to
solve these problems.
| 0 | 0 | 0 | 1 | 0 | 0 |
91 | Does a generalized Chaplygin gas correctly describe the cosmological dark sector? | Yes, but only for a parameter value that makes it almost coincide with the
standard model. We reconsider the cosmological dynamics of a generalized
Chaplygin gas (gCg) which is split into a cold dark matter (CDM) part and a
dark energy (DE) component with constant equation of state. This model, which
implies a specific interaction between CDM and DE, has a $\Lambda$CDM limit and
provides the basis for studying deviations from the latter. Including matter
and radiation, we use the (modified) CLASS code \cite{class} to construct the
CMB and matter power spectra in order to search for a gCg-based concordance
model that is in agreement with the SNIa data from the JLA sample and with
recent Planck data. The results reveal that the gCg parameter $\alpha$ is
restricted to $|\alpha|\lesssim 0.05$, i.e., to values very close to the
$\Lambda$CDM limit $\alpha =0$. This excludes, in particular, models in which
DE decays linearly with the Hubble rate.
| 0 | 1 | 0 | 0 | 0 | 0 |
92 | The effects of subdiffusion on the NTA size measurements of extracellular vesicles in biological samples | The interest in the extracellular vesicles (EVs) is rapidly growing as they
became reliable biomarkers for many diseases. For this reason, fast and
accurate techniques of EVs size characterization are the matter of utmost
importance. One increasingly popular technique is the Nanoparticle Tracking
Analysis (NTA), in which the diameters of EVs are calculated from their
diffusion constants. The crucial assumption here is that the diffusion in NTA
follows the Stokes-Einstein relation, i.e. that the Mean Square Displacement
(MSD) of a particle grows linearly in time (MSD $\propto t$). However, we show
that NTA violates this assumption in both artificial and biological samples,
i.e. a large population of particles show a strongly sub-diffusive behaviour
(MSD $\propto t^\alpha$, $0<\alpha<1$). To support this observation we present
a range of experimental results for both polystyrene beads and EVs. This is
also related to another problem: for the same samples there exists a huge
discrepancy (by the factor of 2-4) between the sizes measured with NTA and with
the direct imaging methods, such as AFM. This can be remedied by e.g. the
Finite Track Length Adjustment (FTLA) method in NTA, but its applicability is
limited in the biological and poly-disperse samples. On the other hand, the
models of sub-diffusion rarely provide the direct relation between the size of
a particle and the generalized diffusion constant. However, we solve this last
problem by introducing the logarithmic model of sub-diffusion, aimed at
retrieving the size data. In result, we propose a novel protocol of NTA data
analysis. The accuracy of our method is on par with FTLA for small
($\simeq$200nm) particles. We apply our method to study the EVs samples and
corroborate the results with AFM.
| 0 | 1 | 0 | 0 | 0 | 0 |
93 | Empirical regression quantile process with possible application to risk analysis | The processes of the averaged regression quantiles and of their modifications
provide useful tools in the regression models when the covariates are not fully
under our control. As an application we mention the probabilistic risk
assessment in the situation when the return depends on some exogenous
variables. The processes enable to evaluate the expected $\alpha$-shortfall
($0\leq\alpha\leq 1$) and other measures of the risk, recently generally
accepted in the financial literature, but also help to measure the risk in
environment analysis and elsewhere.
| 0 | 0 | 1 | 1 | 0 | 0 |
94 | Primordial perturbations from inflation with a hyperbolic field-space | We study primordial perturbations from hyperinflation, proposed recently and
based on a hyperbolic field-space. In the previous work, it was shown that the
field-space angular momentum supported by the negative curvature modifies the
background dynamics and enhances fluctuations of the scalar fields
qualitatively, assuming that the inflationary background is almost de Sitter.
In this work, we confirm and extend the analysis based on the standard approach
of cosmological perturbation in multi-field inflation. At the background level,
to quantify the deviation from de Sitter, we introduce the slow-varying
parameters and show that steep potentials, which usually can not drive
inflation, can drive inflation. At the linear perturbation level, we obtain the
power spectrum of primordial curvature perturbation and express the spectral
tilt and running in terms of the slow-varying parameters. We show that
hyperinflation with power-law type potentials has already been excluded by the
recent Planck observations, while exponential-type potential with the exponent
of order unity can be made consistent with observations as far as the power
spectrum is concerned. We also argue that, in the context of a simple $D$-brane
inflation, the hyperinflation requires exponentially large hyperbolic extra
dimensions but that masses of Kaluza-Klein gravitons can be kept relatively
heavy.
| 0 | 1 | 0 | 0 | 0 | 0 |
95 | Role of Vanadyl Oxygen in Understanding Metallic Behavior of V2O5(001) Nanorods | Vanadium pentoxide (V2O5), the most stable member of vanadium oxide family,
exhibits interesting semiconductor to metal transition in the temperature range
of 530-560 K. The metallic behavior originates because of the reduction of V2O5
through oxygen vacancies. In the present report, V2O5 nanorods in the
orthorhombic phase with crystal orientation of (001) are grown using vapor
transport process. Among three nonequivalent oxygen atoms in a VO5 pyramidal
formula unit in V2O5 structure, the role of terminal vanadyl oxygen (OI) in the
formation of metallic phase above the transition temperature is established
from the temperature-dependent Raman spectroscopic studies. The origin of the
metallic behavior of V2O5 is also understood due to the breakdown of pdpi bond
between OI and nearest V atom instigated by the formation of vanadyl OI
vacancy, confirmed from the downward shift of the bottom most split-off
conduction bands in the material with increasing temperature.
| 0 | 1 | 0 | 0 | 0 | 0 |
96 | Graph Convolution: A High-Order and Adaptive Approach | In this paper, we presented a novel convolutional neural network framework
for graph modeling, with the introduction of two new modules specially designed
for graph-structured data: the $k$-th order convolution operator and the
adaptive filtering module. Importantly, our framework of High-order and
Adaptive Graph Convolutional Network (HA-GCN) is a general-purposed
architecture that fits various applications on both node and graph centrics, as
well as graph generative models. We conducted extensive experiments on
demonstrating the advantages of our framework. Particularly, our HA-GCN
outperforms the state-of-the-art models on node classification and molecule
property prediction tasks. It also generates 32% more real molecules on the
molecule generation task, both of which will significantly benefit real-world
applications such as material design and drug screening.
| 1 | 0 | 0 | 1 | 0 | 0 |
97 | Learning Sparse Representations in Reinforcement Learning with Sparse Coding | A variety of representation learning approaches have been investigated for
reinforcement learning; much less attention, however, has been given to
investigating the utility of sparse coding. Outside of reinforcement learning,
sparse coding representations have been widely used, with non-convex objectives
that result in discriminative representations. In this work, we develop a
supervised sparse coding objective for policy evaluation. Despite the
non-convexity of this objective, we prove that all local minima are global
minima, making the approach amenable to simple optimization strategies. We
empirically show that it is key to use a supervised objective, rather than the
more straightforward unsupervised sparse coding approach. We compare the
learned representations to a canonical fixed sparse representation, called
tile-coding, demonstrating that the sparse coding representation outperforms a
wide variety of tilecoding representations.
| 1 | 0 | 0 | 1 | 0 | 0 |
98 | Almost euclidean Isoperimetric Inequalities in spaces satisfying local Ricci curvature lower bounds | Motivated by Perelman's Pseudo Locality Theorem for the Ricci flow, we prove
that if a Riemannian manifold has Ricci curvature bounded below in a metric
ball which moreover has almost maximal volume, then in a smaller ball (in a
quantified sense) it holds an almost-euclidean isoperimetric inequality. The
result is actually established in the more general framework of non-smooth
spaces satisfying local Ricci curvature lower bounds in a synthetic sense via
optimal transportation.
| 0 | 0 | 1 | 0 | 0 | 0 |
99 | Exponential Sums and Riesz energies | We bound an exponential sum that appears in the study of irregularities of
distribution (the low-frequency Fourier energy of the sum of several Dirac
measures) by geometric quantities: a special case is that for all $\left\{ x_1,
\dots, x_N\right\} \subset \mathbb{T}^2$, $X \geq 1$ and a universal $c>0$ $$
\sum_{i,j=1}^{N}{ \frac{X^2}{1 + X^4 \|x_i -x_j\|^4}} \lesssim \sum_{k \in
\mathbb{Z}^2 \atop \|k\| \leq X}{ \left| \sum_{n=1}^{N}{ e^{2 \pi i
\left\langle k, x_n \right\rangle}}\right|^2} \lesssim \sum_{i,j=1}^{N}{ X^2
e^{-c X^2\|x_i -x_j\|^2}}.$$ Since this exponential sum is intimately tied to
rather subtle distribution properties of the points, we obtain nonlocal
structural statements for near-minimizers of the Riesz-type energy. In the
regime $X \gtrsim N^{1/2}$ both upper and lower bound match for
maximally-separated point sets satisfying $\|x_i -x_j\| \gtrsim N^{-1/2}$.
| 0 | 0 | 1 | 0 | 0 | 0 |
100 | One dimensionalization in the spin-1 Heisenberg model on the anisotropic triangular lattice | We investigate the effect of dimensional crossover in the ground state of the
antiferromagnetic spin-$1$ Heisenberg model on the anisotropic triangular
lattice that interpolates between the regime of weakly coupled Haldane chains
($J^{\prime}\! \!\ll\!\! J$) and the isotropic triangular lattice
($J^{\prime}\!\!=\!\!J$). We use the density-matrix renormalization group
(DMRG) and Schwinger boson theory performed at the Gaussian correction level
above the saddle-point solution. Our DMRG results show an abrupt transition
between decoupled spin chains and the spirally ordered regime at
$(J^{\prime}/J)_c\sim 0.42$, signaled by the sudden closing of the spin gap.
Coming from the magnetically ordered side, the computation of the spin
stiffness within Schwinger boson theory predicts the instability of the spiral
magnetic order toward a magnetically disordered phase with one-dimensional
features at $(J^{\prime}/J)_c \sim 0.43$. The agreement of these complementary
methods, along with the strong difference found between the intra- and the
interchain DMRG short spin-spin correlations; for sufficiently large values of
the interchain coupling, suggests that the interplay between the quantum
fluctuations and the dimensional crossover effects gives rise to the
one-dimensionalization phenomenon in this frustrated spin-$1$ Hamiltonian.
| 0 | 1 | 0 | 0 | 0 | 0 |
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