title:
Tracking Words in Chinese Poetry of Tang and Song Dynasties with the
  China Biographical Database

abstract:
  Large-scale comparisons between the poetry of Tang and Song dynasties shed
light on how words, collocations, and expressions were used and shared among
the poets. That some words were used only in the Tang poetry and some only in
the Song poetry could lead to interesting research in linguistics. That the
most frequent colors are different in the Tang and Song poetry provides a trace
of the changing social circumstances in the dynasties. Results of the current
work link to research topics of lexicography, semantics, and social
transitions. We discuss our findings and present our algorithms for efficient
comparisons among the poems, which are crucial for completing billion times of
comparisons within acceptable time.


title: Learning the Number of Neurons in Deep Networks

abstract:
  Nowadays, the number of layers and of neurons in each layer of a deep network
are typically set manually. While very deep and wide networks have proven
effective in general, they come at a high memory and computation cost, thus
making them impractical for constrained platforms. These networks, however, are
known to have many redundant parameters, and could thus, in principle, be
replaced by more compact architectures. In this paper, we introduce an approach
to automatically determining the number of neurons in each layer of a deep
network during learning. To this end, we propose to make use of structured
sparsity during learning. More precisely, we use a group sparsity regularizer
on the parameters of the network, where each group is defined to act on a
single neuron. Starting from an overcomplete network, we show that our approach
can reduce the number of parameters by up to 80\% while retaining or even
improving the network accuracy.


title: Spotting Rumors via Novelty Detection

abstract:
  Rumour detection is hard because the most accurate systems operate
retrospectively, only recognizing rumours once they have collected repeated
signals. By then the rumours might have already spread and caused harm. We
introduce a new category of features based on novelty, tailored to detect
rumours early on. To compensate for the absence of repeated signals, we make
use of news wire as an additional data source. Unconfirmed (novel) information
with respect to the news articles is considered as an indication of rumours.
Additionally we introduce pseudo feedback, which assumes that documents that
are similar to previous rumours, are more likely to also be a rumour.
Comparison with other real-time approaches shows that novelty based features in
conjunction with pseudo feedback perform significantly better, when detecting
rumours instantly after their publication.


title:
Above-threshold ionization in neon produced by combining optical and
  bichromatic XUV femtosecond pulses

abstract:
  We consider the ionization of neon induced by a femtosecond laser pulse
composed of overlapping, linearly polarized bichromatic extreme ultraviolet and
infrared fields. In particular, we study the effects of the infrared light on a
two-pathway ionization scheme for which Ne 2s22p53s1P is used as intermediate
state. Using time-dependent calculations, supported by a theoretical approach
based on the strong-field approximation, we analyze the ionization probability
and the photoelectron angular distributions associated with the different
sidebands of the ionization spectrum. Complex oscillations of the angular
distribution anisotropy parameters as a function of the infrared light
intensity are revealed. Finally, we demonstrate that coherent control of the
asymmetry is achievable by tuning the infrared frequency to a nearby electronic
transition.


title: Diffusion of active chiral particles

abstract:
  The diffusion of chiral active Brownian particles in three-dimensional space
is studied analytically, by consideration of the corresponding Fokker-Planck
equation for the probability density of finding a particle at position
$\boldsymbol{x}$ and moving along the direction $\hat{\boldsymbol{v}}$ at time
$t$, and numerically, by the use of Langevin dynamics simulations. The analysis
is focused on the marginal probability density of finding a particle at a given
location and at a given time (independently of its direction of motion), which
is found from an infinite hierarchy of differential-recurrence relations for
the coefficients that appear in the multipole expansion of the probability
distribution which contains the whole kinematic information. This approach
allows the explicit calculation of the time dependence of the mean squared
displacement and the time dependence of the kurtosis of the marginal
probability distribution, quantities from which the effective diffusion
coefficient and the "shape" of the positions distribution are examined.
Oscillations between two characteristic values were found in the time evolution
of the kurtosis, namely, between the value that corresponds to a Gaussian and
the one that corresponds to a distribution of spherical shell shape. In the
case of an ensemble of particles, each one rotating around an
uniformly-distributed random axis, it is found evidence of the so called effect
"anomalous, yet Brownian, diffusion", for which particles follow a non-Gaussian
distribution for the positions yet the mean squared displacement is a linear
function of time.


title: Simple modules over finite quantum groups and their Drinfel'd doubles

abstract:
  By finite quantum groups we mean Lusztig's finite-dimensional pointed Hopf
algebras called quantum Frobenius Kernels [9, 10], and their natural
generalizations due to Andruskiewitsch and Schneider [2, 3]. For a Hopf algebra
$H$ in a special class of the latter generalizations, which arises from a pair
of quantum linear spaces, Krop and Radford [8] described the simple modules
over $H$ and over the Drinfel'd double $D(H)$, showing that they fall into a
simple pattern of parametrization. We extend the description to a wider class
of Hopf algebras which includes the quantum Frobenius Kernels, renewing the
parametrization pattern so as to connect directly to the so-called triangular
decomposition.


title: Discreteness of Point Charge in Nonlinear Electrodynamics

abstract:
  We consider two point charges in electrostatic interaction between them
within the framework of a nonlinear model, associated with QED, that provides
finiteness of their field energy. We argue that if the two charges are equal to
each other the repulsion force between them disappears when they are infinitely
close to each other, but remains as usual infinite if their values are
different. This implies that within any system to which such a model may be
applicable the point charge is fractional, it may only be $2^n$-fold of a
certain fundamental charge, n=0,1,2... We find the common field of the two
charges in a dipole approximation, where the separation between them is much
smaller than the observation distance.


title: Joule-Thomson Expansion of Charged AdS Black Holes

abstract:
  In this paper, we study Joule-Thomson effects for charged AdS black holes. We
obtain inversion temperatures and curves. We investigate similarities and
differences between van der Waals fluids and charged AdS black holes for the
expansion. We obtain isenthalpic curves for both systems in $T-P$ plane and
determine the cooling-heating regions.


title: Partial spreads and vector space partitions

abstract:
  Constant-dimension codes with the maximum possible minimum distance have been
studied under the name of partial spreads in Finite Geometry for several
decades. Not surprisingly, for this subclass typically the sharpest bounds on
the maximal code size are known. The seminal works of Beutelspacher and Drake
\& Freeman on partial spreads date back to 1975, and 1979, respectively. From
then until recently, there was almost no progress besides some computer-based
constructions and classifications. It turns out that vector space partitions
provide the appropriate theoretical framework and can be used to improve the
long-standing bounds in quite a few cases. Here, we provide a historic account
on partial spreads and an interpretation of the classical results from a modern
perspective. To this end, we introduce all required methods from the theory of
vector space partitions and Finite Geometry in a tutorial style. We guide the
reader to the current frontiers of research in that field, including a detailed
description of the recent improvements.


title:
On the Energy Efficient Displacement of Random Sensors for Interference
  and Connectivity

abstract:
  This paper investigates the problem of the minimilization of energy
consumption in reallocation of wireless mobile sensors network (WMSN) to assure
good communication without interference.
  Fix $d\in\mathbb{N}\setminus\{0\}.$ Assume $n$ sensors are initially randomly
placed in the hyperoctant $[0,\infty)^d$ according to $d$ identical and
independent Poisson processes each with arrival rate $\lambda>0.$
  Let $0< s \le v$ be given real numbers. We are allowed to move the sensors,
so that every two consecutive sensors are placed at distance greater than or
equal to $s$ and less than or equal to $v.$
  Fix $a\ge 1.$ Assume that $i-$th sensor is displaced a distance equal to
$m(i).$ The cost measure for the displacement of the team of sensors is the sum
$\sum_{i=1}^{n}d_i^a$ ($a-$total movement).
  In this work, we discover and explain a sharp decline and a sharp increase (a
threshold phenomena) in the expected minimal $a-$total movement around the
interference-connectivity distances $s,v$ equal to $\frac{1}{\lambda}.$


title:
Solving the Model of the Risk of Microcephaly Induced by the Zika Virus
  (ZIKV) by a Modified Moving least Squares Method

abstract:
  The aim of this work is the application of the Meshfree methods for solving
systems of stiff ordinary differential equations. These methods are based on
the Moving least squares (MLS), generalized moving least squares (GMLS)
approximation and Modified Moving least squares (MMLS) method. GMLS makes a
considerable reduction in the cost of numerical methods. In fact, GMLS method
is effect operator on the basis polynomial rather than the complicated MLS
shape functions. Besides that the modified MMLS approximation method avoids
undue a singular moment matrix. This allows the base functions to be of order
greater than two with the same size of the support domain as the linear base
functions. We also show the estimation of the error propagation obtained of the
numerical solution of the systems of stiff ordinary differential equation. Some
examples are provided to show that the GMLS and MMLS methods are more reliable
(accurate) than classic MLS method.Finally, the (our) proposed methods are
validated by solving ZIKV model which is a system of ODEs.


title:
A simple and accurate algorithm for path integral molecular dynamics
  with the Langevin thermostat

abstract:
  We introduce a novel simple algorithm for thermostatting path integral
molecular dynamics (PIMD) with the Langevin equation. The staging
transformation of path integral beads is employed for demonstration. The
optimum friction coefficients for the staging modes in the free particle limit
are used for all systems. In comparison to the path integral Langevin equation
(PILE) thermostat, the new algorithm exploits a different order of splitting
for the phase space propagator associated to the Langevin equation. While the
error analysis is made for both algorithms, they are also employed in the PIMD
simulations of three realistic systems (the H2O molecule, liquid para-hydrogen,
and liquid water) for comparison. It is shown that the new thermostat increases
the time interval of PIMD by a factor of 4~6 or more for achieving the same
accuracy. In addition, supplemental material shows the error analysis made for
the algorithms when the normal-mode transformation of path integral beads is
used.


title:
On the generalized circle problem for a random lattice in large
  dimension

abstract:
  In this note we study the error term R_{n,L}(x) in the generalized circle
problem for a ball of volume x and a random lattice L of large dimension n. Our
main result is the following functional central limit theorem: Fix an arbitrary
function f(n) from the positive integers to the positive real line, tending to
infinity with n but with subexponential growth. Then, the random function t ->
(2f(n))^{-1/2} R_{n,L}(t f(n)) on the interval [0,1] converges in distribution
to one-dimensional Brownian motion as n tends to infinity. The proof goes via
convergence of moments, and for the computations we develop a new version of
Rogers' mean value formula. For the individual k:th moment of the variable
(2f(n))^{-1/2} R_{n,L}(f(n)) we prove convergence to the corresponding Gaussian
moment more generally for functions f satisfying f(n)<<e^{cn} for any fixed c
in an interval 0<c<c_k, where c_k is a constant depending on k whose optimal
value we determine.


title:
Non-Elastic Processes in Atom Rydberg-Atom Collisions: Review of State
  of Art and Problems

abstract:
  In our previous research, it has been demonstrated that such inelastic
processes in atom Rydberg-atom collisions, as chemi-ionization and (n-n')
mixing, should be considered together. Here we will review the present state of
the art and the actual problems will be discussed. In this context, we will
consider the influence of the (n-n')-mixing during a symmetric atom
Rydberg-atom collision processes on the intensity of chemi-ionization process.
It will be taken into account H(1s) + H*(n) collisional systems, where the
principal quantum number n $>>$ 1. It will be demonstrated that the inclusion
of (n-n') mixing in the calculation, influences significantly on the values of
chemi-ionization rate coefficients, particularly in the lower part of the block
of the Rydberg states. Different possible channels of the (n-n')-mixing
influence on chemi-ionization rate coefficients will be demonstrated. The
possibility of interpretation of the (n-n')-mixing influence will be considered
on the basis of two existing methods for describing of the inelastic processes
in symmetrical atom Rydberg-atom collisions.


title: A Survey of Methods for Collective Communication Optimization and Tuning

abstract:
  New developments in HPC technology in terms of increasing computing power on
multi/many core processors, high-bandwidth memory/IO subsystems and
communication interconnects, pose a direct impact on software and runtime
system development. These advancements have become useful in producing
high-performance collective communication interfaces that integrate efficiently
on a wide variety of platforms and environments. However, number of
optimization options that shows up with each new technology or software
framework has resulted in a \emph{combinatorial explosion} in feature space for
tuning collective parameters such that finding the optimal set has become a
nearly impossible task. Applicability of algorithmic choices available for
optimizing collective communication depends largely on the scalability
requirement for a particular usecase. This problem can be further exasperated
by any requirement to run collective problems at very large scales such as in
the case of exascale computing, at which impractical tuning by brute force may
require many months of resources. Therefore application of statistical, data
mining and artificial Intelligence or more general hybrid learning models seems
essential in many collectives parameter optimization problems. We hope to
explore current and the cutting edge of collective communication optimization
and tuning methods and culminate with possible future directions towards this
problem.


title:
Space-time finite element approximation of the Biot poroelasticity
  system with iterative coupling

abstract:
  In this work we analyze an optimized artificial fixed-stress iteration scheme
for the numerical approximation of the Biot system modelling fluid flow in
deformable porous media. The iteration is based on a prescribed constant
artificial volumetric mean total stress in the first half step. The
optimization comes through the adaptation of a numerical stabilization or
tuning parameter and aims at an acceleration of the iterations. The separated
subproblems of fluid flow, written as a mixed first order in space system, and
mechanical deformation are discretized by space-time finite element methods of
arbitrary order. Continuous and discontinuous discretizations of the time
variable are encountered. The convergence of the iteration schemes is proved
for the continuous and fully discrete case. The choice of the optimization
parameter is identified in the proofs of convergence of the iterations. The
analyses are illustrated and confirmed by numerical experiments.


title: A generalized volume law for entanglement entropy on the fuzzy sphere

abstract:
  We investigate entanglement entropy in a scalar field theory on the fuzzy
sphere. The theory is realized by a matrix model. In our previous study, we
confirmed that entanglement entropy in the free case is proportional to the
square of the boundary area of a focused region. Here we argue that this
behavior of entanglement entropy can be understood by the fact that the theory
is regularized by matrices, and further examine the dependence of entanglement
entropy on the matrix size. In the interacting case, by performing Monte Carlo
simulations, we observe a transition from a generalized volume law, which is
obtained by integrating the square of area law, to the square of area law.


title:
Semi-Infinite Quasi-Toeplitz Matrices with Applications to QBD
  Stochastic Processes

abstract:
  Denote by $\mathcal{W}_1$ the set of complex valued functions of the form
$a(z)=\sum_{i=-\infty}^{+\infty}a_iz^i$ which are continuous on the unit
circle, and such that $\sum_{i=-\infty}^{+\infty}|ia_i|<\infty$. We call CQT
matrix a quasi-Toeplitz matrix $A$, associated with a continuous symbol
$a(z)\in\mathcal W_1$, of the form $A=T(a)+E$, where
$T(a)=(t_{i,j})_{i,j\in\mathbb{Z}^+}$ is the semi-infinite Toeplitz matrix such
that $t_{i,j}=a_{j-i}$, for $i,j\in\mathbb Z^+$, and
$E=(e_{i,j})_{i,j\in\mathbb{Z}^+}$ is a semi-infinite matrix such that
$\sum_{i,j=1}^{+\infty}|e_{i,j}|$ is finite. We prove that the class of CQT
matrices is a Banach algebra with a suitable sub-multiplicative matrix norm
$\|\cdot\|$. We introduce a finite representation of CQT matrices together with
algorithms which implement elementary matrix operations. An application to
solving quadratic matrix equations of the kind $AX^2+BX+C=0$, encountered in
the solution of Quasi-Birth and Death (QBD) stochastic processes with a
denumerable set of phases, is presented where $A,B,C$ are CQT matrices.


title:
Strong constraint on hadronic models of blazar activity from Fermi and
  IceCube stacking analysis

abstract:
  High-energy emission from blazars is produced by electrons which are either
accelerated directly (the assumption of leptonic models of blazar activity) or
produced in interactions of accelerated protons with matter and radiation
fields (the assumption of hadronic models). The hadronic models predict that
gamma-ray emission is accompanied by neutrino emission with comparable energy
flux but with a different spectrum. We derive constraints on the hadronic
models of activity of blazars imposed by non-detection of neutrino flux from a
population of gamma-ray emitting blazars. We stack the gamma-ray and muon
neutrino flux from 749 blazars situated in the declination strip above -5
degrees. Non-detection of neutrino flux from the stacked blazar sample rules
out the proton induced cacade models in which the high-energy emission is
powered by interactions of shock-accelerated proton beam in the AGN jet with
the ambient matter or with the radiation field of the black hole accretion
disk. The result remains valid also for the case of interactions in the
scattered radiation field in the broad line region. IceCube constraint could be
avoided if the spectrum of accelerated protons is sharply peaking in the
ultra-high-energy cosmic ray range, as in the models of acceleration in the
magnetic reconnection regions or in the vacuum gaps of black hole
magnetospheres. Models based on these acceleration mechanisms are consistent
with the data only if characteristic energies of accelerated protons are higher
than 1e19 eV.


title:
Inverse Magnetic Catalysis from improved Holographic QCD in the
  Veneziano limit

abstract:
  We study the dependence of the chiral condensate on external magnetic field
in the context of holographic QCD at large number of flavors. We consider a
holographic QCD model where the flavor degrees of freedom fully backreact on
the color dynamics. Perturbative QCD calculations have shown that $B$ acts
constructively on the chiral condensate, a phenomenon called "magnetic
catalysis". In contrast, recent lattice calculations show that, depending on
the number of flavors and temperature, the magnetic field may also act
destructively, which is called "inverse magnetic catalysis". Here we show that
the holographic theory is capable of both behaviors depending on the choice of
parameters. For reasonable choice of the potentials entering the model we find
qualitative agreement with the lattice expectations. Our results provide
insight for the physical reasons behind the inverse magnetic catalysis. In
particular, we argue that the backreaction of the flavors to the background
geometry decatalyzes the condensate.


title:
Multiloop Amplitudes of Light-cone Gauge NSR String Field Theory in
  Noncritical Dimensions

abstract:
  Feynman amplitudes of light-cone gauge superstring field theory are
ill-defined because of various divergences. In a previous paper, one of the
authors showed that taking the worldsheet theory to be the one in a linear
dilaton background $\Phi=-iQX^{1}$ with Feynman $i\varepsilon$
$(\varepsilon>0)$ and $Q^{2}>10$ yields finite amplitudes. In this paper, we
apply this worldsheet theory to dimensional regularization of the light-cone
gauge NSR superstring field theory. We concentrate on the amplitudes for even
spin structure with external lines in the (NS,NS) sector. We show that the
multiloop amplitudes are indeed regularized in our scheme and that they
coincide with the results in the first-quantized formalism through the analytic
continuation $Q\to0$.


title:
On the equivalence between some jumping SDEs with rough coefficients and
  some non-local PDEs

abstract:
  We study some jumping SDE and the corresponding Fokker-Planck (or Kolmogorov
forward) equation, which is a non-local PDE. We assume only some measurability
and growth conditions on the coefficients. We prove that for any weak solution
$(f_t)_{t\in [0,T]}$ of the PDE, there exists a weak solution to the SDE of
which the time marginals are given by $(f_t)_{t\in[0,T]}$. As a corollary, we
deduce that for any given initial condition, existence for the PDE is
equivalent to weak existence for the SDE and uniqueness in law for the SDE
implies uniqueness for the PDE. This extends some ideas of Figalli [5]
concerning continuous SDEs and local PDEs.


title: Quantized neural network design under weight capacity constraint

abstract:
  The complexity of deep neural network algorithms for hardware implementation
can be lowered either by scaling the number of units or reducing the
word-length of weights. Both approaches, however, can accompany the performance
degradation although many types of research are conducted to relieve this
problem. Thus, it is an important question which one, between the network size
scaling and the weight quantization, is more effective for hardware
optimization. For this study, the performances of fully-connected deep neural
networks (FCDNNs) and convolutional neural networks (CNNs) are evaluated while
changing the network complexity and the word-length of weights. Based on these
experiments, we present the effective compression ratio (ECR) to guide the
trade-off between the network size and the precision of weights when the
hardware resource is limited.


title: Slow links, fast links, and the cost of gossip

abstract:
  Consider the classical problem of information dissemination: one (or more)
nodes in a network have some information that they want to distribute to the
remainder of the network. In this paper, we study the cost of information
dissemination in networks where edges have latencies, i.e., sending a message
from one node to another takes some amount of time. We first generalize the
idea of conductance to weighted graphs by defining $\phi_*$ to be the "critical
conductance" and $\ell_*$ to be the "critical latency". One goal of this paper
is to argue that $\phi_*$ characterizes the connectivity of a weighted graph
with latencies in much the same way that conductance characterizes the
connectivity of unweighted graphs.
  We give near tight lower and upper bounds on the problem of information
dissemination, up to polylogarithmic factors. Specifically, we show that in a
graph with (weighted) diameter $D$ (with latencies as weights) and maximum
degree $\Delta$, any information dissemination algorithm requires at least
$\Omega(\min(D+\Delta, \ell_*/\phi_*))$ time % in the worst case. We show
several variants of the lower bound (e.g., for graphs with small diameter,
graphs with small max-degree, etc.) by reduction to a simple combinatorial
game.
  We then give nearly matching algorithms, showing that information
dissemination can be solved in $O(\min((D+\Delta)\log^3{n}, (\ell_*/\phi_*)\log
n)$ time. This is achieved by combining two cases. We show that the classical
push-pull algorithm is (near) optimal when the diameter or the maximum degree
is large. For the case where the diameter and the maximum degree are small, we
give an alternative strategy in which we first discover the latencies and then
use an algorithm for known latencies based on a weighted spanner construction.
(Our algorithms are within polylogarithmic factors of being tight both for
known and unknown latencies.)


title: Regression-based complexity reduction of the nested Monte Carlo methods

abstract:
  In this paper we propose a novel dual regression-based approach for pricing
American options. This approach reduces the complexity of the nested Monte
Carlo method and has especially simple form for time discretised diffusion
processes. We analyse the complexity of the proposed approach both in the case
of fixed and increasing number of exercise dates. The method is illustrated by
several numerical examples.


title:
Beyond Deep Residual Learning for Image Restoration: Persistent
  Homology-Guided Manifold Simplification

abstract:
  The latest deep learning approaches perform better than the state-of-the-art
signal processing approaches in various image restoration tasks. However, if an
image contains many patterns and structures, the performance of these CNNs is
still inferior. To address this issue, here we propose a novel feature space
deep residual learning algorithm that outperforms the existing residual
learning. The main idea is originated from the observation that the performance
of a learning algorithm can be improved if the input and/or label manifolds can
be made topologically simpler by an analytic mapping to a feature space. Our
extensive numerical studies using denoising experiments and NTIRE single-image
super-resolution (SISR) competition demonstrate that the proposed feature space
residual learning outperforms the existing state-of-the-art approaches.
Moreover, our algorithm was ranked third in NTIRE competition with 5-10 times
faster computational time compared to the top ranked teams. The source code is
available on page : https://github.com/iorism/CNN.git


title:
On blow-up solutions of differential equations with Poincar\'e-type
  compactifications

abstract:
  We provide explicit criteria for blow-up solutions of autonomous ordinary
differential equations. Ideas are based on the quasi-homogeneous
desingularization (blowing-up) of singularities and compactifications of phase
spaces, which suitably desingularize singularities at infinity. We derive
several type of compactifications and show that dynamics at infinity is
qualitatively independent of the choice of such compactifications. We also show
that hyperbolic invariant sets, such as equilibria and periodic orbits, at
infinity induce blow-up solutions with specific blow-up rates. In particular,
blow-up solutions can be described as trajectories on stable manifolds of
equilibria at infinity for associated vector fields. Finally, we demonstrate
blow-up solutions of several differential equations.


title: Meissner effect and a stringlike interaction

abstract:
  We find that a recently proposed interaction involving the vorticity current
of electrons, which radiatively induces a photon mass in 3+1 dimensions in the
low-energy effective theory, corresponds to confining strings (linear
potential) between electrons.


title: Gaussian theory for spatially distributed self-propelled particles

abstract:
  Obtaining a reduced description with particle and momentum flux densities
outgoing from the microscopic equations of motion of the particles requires
approximations. The usual method, we refer to as truncation method, is to zero
Fourier modes of the orientation distribution starting from a given number.
Here we propose another method to derive continuum equations for interacting
self-propelled particles. The derivation is based on a Gaussian approximation
(GA) of the distribution of the direction of particles. First, by means of
simulation of the microscopic model we justify that the distribution of
individual directions fits well to a wrapped Gaussian distribution. Second, we
numerically integrate the continuum equations derived in the GA in order to
compare with results of simulations. We obtain that the global polarization in
the GA exhibits a hysteresis in dependence on the noise intensity. It shows
qualitatively the same behavior as we find in particles simulations. Moreover,
both global polarizations agree perfectly for low noise intensities. The
spatio-temporal structures of the GA are also in agreement with simulations. We
conclude that the GA shows qualitative agreement for a wide range of noise
intensities. In particular, for low noise intensities the agreement with
simulations is better as other approximations, making the GA to an acceptable
candidates of describing spatially distributed self-propelled particles.


title: Weyl modules and Weyl functors for Lie superalgebras

abstract:
  Given an algebraically closed field $\Bbbk$ of characteristic zero, a Lie
superalgebra $\mathfrak{g}$ over $\Bbbk$ and an associative, commutative
$\Bbbk$-algebra $A$ with unit, a Lie superalgebra of the form $\mathfrak{g}
\otimes_\Bbbk A$ is known as a map superalgebra. Map superalgebras generalize
important classes of Lie superalgebras, such as, loop superalgebras (where
$A=\Bbbk[t, t^{-1}]$), and current superalgebras (where $A=\Bbbk[t]$). In this
paper, we define Weyl functors, global and local Weyl modules for all map
superalgebras where $\mathfrak{g}$ is either $\mathfrak{sl} (n,n)$ with $n \ge
2$, or a finite-dimensional simple Lie superalgebra not of type
$\mathfrak{q}(n)$. Under certain conditions on the triangular decomposition of
these Lie superalgebras we prove that global and local Weyl modules satisfy
certain universal and tensor product decomposition properties. We also give
necessary and sufficient conditions for local (resp. global) Weyl modules to be
finite dimensional (resp. finitely generated).


title: Multi-study Factor Analysis

abstract:
  We introduce a novel class of factor analysis methodologies for the joint
analysis of multiple studies. The goal is to separately identify and estimate
1) common factors shared across multiple studies, and 2) study-specific
factors. We develop a fast Expectation Conditional-Maximization algorithm for
parameter estimates and we provide a procedure for choosing the common and
specific factor. We present simulations evaluating the performance of the
method and we illustrate it by applying it to gene expression data in ovarian
cancer. In both cases, we clarify the benefits of a joint analysis compared to
the standard factor analysis. We hope to have provided a valuable tool to
accelerate the pace at which we can combine unsupervised analysis across
multiple studies, and understand the cross-study reproducibility of signal in
multivariate data.


title:
Effect of finite range interactions on roton mode softening in a
  multi-component BEC

abstract:
  We consider the Gross-Pitaevskii(GP) model of a Bose-Einstein Condensate(BEC)
for single-component and multi-component BEC. The pseudopotential for s-wave
scattering between atoms is taken to be of width of the order of the s-wave
scattering length. Such an interaction giving rise to a roton minimum in the
spectrum of elementary excitations of a single component BEC is well known.
However, softening roton modes takes us in the strongly interacting BEC regime
where three body losses occur. We study the roton mode softening for a
multi-component BEC. We show that by increasing the number of components of a
multi-component BEC, the roton mode can be softened at a progressively lower
value of the gas parameter ($a^{3}n$), thus reducing three body losses.


title: An Uncertainty Principle For Completely Positive Maps

abstract:
  We present an "uncertainty principle" for quantum channels, showing a
relationship between the dimensions of the range of a channel and the range of
its complement. We examine some interesting specific cases, and discuss
consequences for privacy of quantum channels.


title:
Cone distribution functions and quantiles for multivariate random
  variables

abstract:
  Set-valued quantiles for multivariate distributions with respect to a general
convex cone are introduced which are based on a family of (univariate)
distribution functions rather than on the joint distribution function. It is
shown that these quantiles enjoy basically all the properties of univariate
quantile functions. Relationships to families of univariate quantile functions
and to depth functions are discussed. Finally, a corresponding Value at Risk
for multivariate random variables as well as stochastic orders are introduced
via the set-valued approach.


title:
Alloying, de-alloying and reentrant alloying in (sub-)monolayer growth
  of Ag on Pt(111)

abstract:
  An in-situ nanoscopic investigation of the prototypical surface alloying
system Ag/Pt(111) is reported. The morphology and the structure of the
ultrathin Ag-Pt film is studied using Low Energy Electron Microscopy during
growth at about 800 K. An amazingly rich dynamic behaviour is uncovered in
which stress relieve plays a governing role. Initial growth leads to surface
alloying with prolonged and retarded nucleation of ad-islands. Beyond 50%
coverage de-alloying proceeds, joined by partial segregation of Pt towards the
centre of large islands in violent processes. Upon coalescence the irregularly
shaped vacancy clusters are filled by segregating Pt, which then take a compact
shape (black spots). As a result at around 85% coverage the strain of the
initially pseudo-morphological film is almost completely relieved and
Pt-segregation is at its maximum. Further deposition of Ag leads to transient
re-entrant alloying and recovery of the pseudo-morphological layer. The black
spots persist even in/on several layers thick films. Ex-situ atomic force
microscopy data confirm that these are constituted by probably amorphous
Pt(-rich) structures. The (sub-)monolayer films are very much heterogeneous.


title: Invertible Conditional GANs for image editing

abstract:
  Generative Adversarial Networks (GANs) have recently demonstrated to
successfully approximate complex data distributions. A relevant extension of
this model is conditional GANs (cGANs), where the introduction of external
information allows to determine specific representations of the generated
images. In this work, we evaluate encoders to inverse the mapping of a cGAN,
i.e., mapping a real image into a latent space and a conditional
representation. This allows, for example, to reconstruct and modify real images
of faces conditioning on arbitrary attributes. Additionally, we evaluate the
design of cGANs. The combination of an encoder with a cGAN, which we call
Invertible cGAN (IcGAN), enables to re-generate real images with deterministic
complex modifications.


title:
Negative Feedback, Linearity and Parameter Invariance in Linear
  Electronics

abstract:
  Negative feedback is a powerful approach capable of improving several aspects
of a system. In linear electronics, it has been critical for allowing
invariance to device properties. Negative feedback is also known to enhance
linearity in amplification, which is one of the most important foundations of
linear electronics. At the same time, thousands of transistors types have been
made available, suggesting that these devices, in addition to their known
variability of parameters, have distinguishing properties. The current work
reports a systematic approach to quantifying the potential of negative
feedback, with respect to bipolar transistors, as a means to providing device
invariance and linearity. Several methods, including concepts from multivariate
statistics and complex systems, are applied at the theoretical as well as
experimental levels, and a number of interesting results are obtained and
discussed. For instance, it has been verified that the transistors types indeed
have well-defined characteristics which clearly segregate them into groups. The
addition of feedback at moderate and intense levels promoted uniformization of
the properties of these transistors when used in a class A common emitter
configuration. However, such effect occurred with different efficiency
regarding the considered device features, and even intense feedback was unable
to completely eliminate device dependence. This indicates that it would be
interesting to consider the device properties in linear design even when
negative feedback is applied. We also verified that the linearization induced
in the considered experiments is relatively modest, with effects that depend on
type of transfer function of the original devices.


title: Decomposition of bent generalized Boolean functions

abstract:
  A one to one correspondence between regular generalized bent functions from
$\F_2^n$ to $\Z_{2^m},$ and $m-$tuples of Boolean bent functions is
established. This correspondence maps self-dual (resp. anti-self-dual)
generalized bent functions to $m-$tuples of self-dual (resp. anti self-dual)
Boolean bent functions. An application to the classification of regular
generalized bent functions under the extended affine group is given.


title:
Analytical solutions of the coupled Gross-Pitaevskii equations for the
  three-species Bose-Einstein condensates

abstract:
  The coupled Gross-Pitaevskii equations for the g.s. of the three-species
condensates (3-BEC) have been solved analytically under the Thomas-Fermi
approximation. Six types of spatial configurations in miscible phase are found.
The whole parameter-space has been divided into zones each supports a specific
configuration (miscible or immiscible). The borders of the zones are described
by analytical formulae. Due to the division, the variation of the spatial
configuration against the parameters can be visualized, and the effects of the
parameters can be thereby understood. There are regions in the parameter-space
where the configuration is highly sensitive to the parameters. These regions
are tunable and valuable for the determination of the parameters.


title: Quantum filtering equations for system driven by non-classical fields

abstract:
  Using Gardiner and Collet's input-output model and the concept of cascade
system, we determine the filtering equation for a quantum system driven by
chosen non-classical states of light. The quantum system and electromagnetic
field are described by making use of quantum stochastic unitary evolution. We
consider two examples of the non-classical states of the field: a combination
of vacuum and single photon states and a mixture of two coherent states. We
describe the stochastic evolution conditioned on the results of the photon
counting and quadrature measurements.


title:
A Floquet-Bloch transform based numerical method for scattering from
  locally perturbed periodic surfaces

abstract:
  Scattering problems for periodic structures have been studied a lot in the
past few years. A main idea for numerical solution methods is to reduce such
problems to one periodicity cell. In contrast to periodic settings, scattering
from locally perturbed periodic surfaces is way more challenging. In this
paper, we introduce and analyze a new numerical method to simulate scattering
from locally perturbed periodic structures based on the Bloch transform. As
this transform is applied only in periodic domains, we firstly rewrite the
scattering problem artificially in a periodic domain. With the help of the
Bloch transform, we secondly transform this problem into a coupled family of
quasiperiodic problems posed in the periodicity cell. A numerical scheme then
approximates the family of quasiperiodic solutions (we rely on the finite
element method) and backtransformation provides the solution to the original
scattering problem. In this paper, we give convergence analysis and error
bounds for a Galerkin discretization in the spatial and the quasiperiodicity's
unit cells. We also provide a simple and efficient way for implementation that
does not require numerical integration in the quasiperiodicity, together with
numerical examples for scattering from locally perturbed periodic surfaces
computed by this scheme.


title: Carlitz Rank and Index of Permutation Polynomials

abstract:
  Carlitz rank and index are two important measures for the complexity of a
permutation polynomial $f(x)$ over the finite field $\F_q$. In particular, for
cryptographic applications we need both, a high Carlitz rank and a high index.
In this article we study the relationship between Carlitz rank $Crk(f)$ and
index $Ind(f)$. More precisely, if the permutation polynomial is neither close
to a polynomial of the form $ax$ nor a rational function of the form $ax^{-1}$,
then we show that $Crk(f)>q- \max\{3 Ind(f),(3q)^{1/2}\}$. Moreover we show
that the permutation polynomial which represents the discrete logarithm
guarantees both a large index and a large Carlitz rank.


title: Ordinal Constrained Binary Code Learning for Nearest Neighbor Search

abstract:
  Recent years have witnessed extensive attention in binary code learning,
a.k.a. hashing, for nearest neighbor search problems. It has been seen that
high-dimensional data points can be quantized into binary codes to give an
efficient similarity approximation via Hamming distance. Among existing
schemes, ranking-based hashing is recent promising that targets at preserving
ordinal relations of ranking in the Hamming space to minimize retrieval loss.
However, the size of the ranking tuples, which shows the ordinal relations, is
quadratic or cubic to the size of training samples. By given a large-scale
training data set, it is very expensive to embed such ranking tuples in binary
code learning. Besides, it remains a dificulty to build ranking tuples
efficiently for most ranking-preserving hashing, which are deployed over an
ordinal graph-based setting. To handle these problems, we propose a novel
ranking-preserving hashing method, dubbed Ordinal Constraint Hashing (OCH),
which efficiently learns the optimal hashing functions with a graph-based
approximation to embed the ordinal relations. The core idea is to reduce the
size of ordinal graph with ordinal constraint projection, which preserves the
ordinal relations through a small data set (such as clusters or random
samples). In particular, to learn such hash functions effectively, we further
relax the discrete constraints and design a specific stochastic gradient decent
algorithm for optimization. Experimental results on three large-scale visual
search benchmark datasets, i.e. LabelMe, Tiny100K and GIST1M, show that the
proposed OCH method can achieve superior performance over the state-of-the-arts
approaches.


title: A swift introduction to holomorphic foliations with singularities

abstract:
  These are the notes of a series of lectures delivered by the author at the
Graduate School of Mathematics of the University of Tokyo, during the month of
October 2015. They were meant to be as self-contained as possible, taking into
account time and space. The basic idea was to introduce the concepts and some
of the basic results in the theory of holomorphic foliations with
singularities. Another goal is to guide the reader to some of the recent
questions and problems in the field, providing in this way a motivating
introduction to those who are interested in studying a new subject.


title: TOV or OV?, the whole story

abstract:
  In a recent manuscript published in the Arxives (arXiv:1610.03049v1), it is
claimed that it should be more appropriate to refer to the equation of
hydrostatic equilibrium in a static spherically symmetric spacetime, supported
by an isotropic perfect fluid, as the "Oppenheimer-Volkoff (OV) equation",
instead of the "Tolman-Oppenheimer-Volkoff (TOV)", as is frequently done. As we
shall see in this brief note, such a claim is not supported by the existing
bibliography.


title:
A Case for Malleable Thread-Level Linear Algebra Libraries: The LU
  Factorization with Partial Pivoting

abstract:
  We propose two novel techniques for overcoming load-imbalance encountered
when implementing so-called look-ahead mechanisms in relevant dense matrix
factorizations for the solution of linear systems. Both techniques target the
scenario where two thread teams are created/activated during the factorization,
with each team in charge of performing an independent task/branch of execution.
The first technique promotes worker sharing (WS) between the two tasks,
allowing the threads of the task that completes first to be reallocated for use
by the costlier task. The second technique allows a fast task to alert the
slower task of completion, enforcing the early termination (ET) of the second
task, and a smooth transition of the factorization procedure into the next
iteration.
  The two mechanisms are instantiated via a new malleable thread-level
implementation of the Basic Linear Algebra Subprograms (BLAS), and their
benefits are illustrated via an implementation of the LU factorization with
partial pivoting enhanced with look-ahead. Concretely, our experimental results
on a six core Intel-Xeon processor show the benefits of combining WS+ET,
reporting competitive performance in comparison with a task-parallel
runtime-based solution.


title: Grasp Learning by Sampling from Demonstration

abstract:
  Robotic grasping traditionally relies on object features or shape information
for learning new or applying already learned grasps. We argue however that such
a strong reliance on object geometric information renders grasping and grasp
learning a difficult task in the event of cluttered environments with high
uncertainty where reasonable object models are not available. This being so, in
this paper we thus investigate the application of model-free stochastic
optimization for grasp learning. For this, our proposed learning method
requires just a handful of user-demonstrated grasps and an initial prior by a
rough sketch of an object's grasp affordance density, yet no object geometric
knowledge except for its pose. Our experiments show promising applicability of
our proposed learning method.


title: Active and Transfer Learning of Grasps by Sampling from Demonstration

abstract:
  We guess humans start acquiring grasping skills as early as at the infant
stage by virtue of two key processes. First, infants attempt to learn grasps
for known objects by imitating humans. Secondly, knowledge acquired during this
process is reused in learning to grasp novel objects. We argue that these
processes of active and transfer learning boil down to a random search of
grasps on an object, suitably biased by prior experience. In this paper we
introduce active learning of grasps for known objects as well as transfer
learning of grasps for novel objects grounded on kernel adaptive, mode-hopping
Markov Chain Monte Carlo. Our experiments show promising applicability of our
proposed learning methods.


title: Active and Transfer Learning of Grasps by Kernel Adaptive MCMC

abstract:
  Human ability of both versatile grasping of given objects and grasping of
novel (as of yet unseen) objects is truly remarkable. This probably arises from
the experience infants gather by actively playing around with diverse objects.
Moreover, knowledge acquired during this process is reused during learning of
how to grasp novel objects. We conjecture that this combined process of active
and transfer learning boils down to a random search around an object, suitably
biased by prior experience, to identify promising grasps. In this paper we
present an active learning method for learning of grasps for given objects, and
a transfer learning method for learning of grasps for novel objects. Our
learning methods apply a kernel adaptive Metropolis-Hastings sampler that
learns an approximation of the grasps' probability density of an object while
drawing grasp proposals from it. The sampler employs simulated annealing to
search for globally-optimal grasps. Our empirical results show promising
applicability of our proposed learning schemes.


title:
Generation of robust entangled states in a non-hermitian periodically
  driven two-band Bose-Hubbard system

abstract:
  A many-body Wannier-Stark system coupled to an effective reservoir is studied
within a non-Hermitian approach in the presence of a periodic driving. We show
how the interplay of dissipation and driving dynamically induces a subspace of
states which are very robust against dissipation. We numerically probe the
structure of these asymptotic states and their robustness to imperfections in
the initial-state preparation and to the size of the system. Moreover, the
asymptotic states are found to be strongly entangled making them interesting
for further applications.


title:
Bipolar Conduction is the Origin of the Electronic Transition in
  Pentatellurides: Metallic vs. Semiconducting Behavior

abstract:
  The pentatellurides, ZrTe5 and HfTe5 are layered compounds with one
dimensional transition-metal chains that show a never understood temperature
dependent transition in transport properties as well as recently discovered
properties suggesting topological semimetallic behavior. Here we show that
these materials are semiconductors and that the electronic transition is due to
a combination of bipolar effects and different anisotropies for electrons and
holes. We report magneto-transport properties for two kinds of ZrTe5 single
crystals grown with the chemical vapor transport (S1) and the flux method (S2),
respectively. These have distinct transport properties at zero field: the S1
displays a metallic behavior with a pronounced resistance peak and a sudden
sign reversal in thermopower at approximately 130 K, consistent with previous
observations of the electronic transition; in strikingly contrast, the S2
exhibits a semiconducting-like behavior at low temperatures and a positive
thermopower over the whole temperature range. Refinements on the single-crystal
X-ray diffraction and the energy dispersive spectroscopy analysis revealed the
presence of noticeable Te-vacancies in the sample S1, confirming that the
widely observed anomalous transport behaviors in pentatellurides actually take
place in the Te-deficient samples. Electronic structure calculations show
narrow gap semiconducting behavior, with different transport anisotropies for
holes and electrons. For the degenerately doped n-type samples, our transport
calculations can result in a resistivity peak and crossover in thermopower from
negative to positive at temperatures close to that observed experimentally. Our
present work resolves the longstanding puzzle regarding the anomalous transport
behaviors of pentatellurides, and also resolves the electronic structure in
favor of a semiconducting state.


title: On MDS Negacyclic LCD Codes

abstract:
  Linear codes with complementary duals (LCD) have a great deal of significance
amongst linear codes. Maximum distance separable (MDS) codes are also an
important class of linear codes since they achieve the greatest error
correcting and detecting capabilities for fixed length and dimension. The
construction of linear codes that are both LCD and MDS is a hard task in coding
theory. In this paper, we study the constructions of LCD codes that are MDS
from negacyclic codes over finite fields of odd prime power $q$ elements. We
construct four families of MDS negacyclic LCD codes of length
$n|\frac{{q-1}}{2}$, $n|\frac{{q+1}}{2}$ and a family of negacyclic LCD codes
of length $n=q-1$. Furthermore, we obtain five families of $q^{2}$-ary
Hermitian MDS negacyclic LCD codes of length $n|\left( q-1\right)$ and four
families of Hermitian negacyclic LCD codes of length $n=q^{2}+1.$ For both
Euclidean and Hermitian cases the dimensions of these codes are determined and
for some classes the minimum distances are settled. For the other cases, by
studying $q$ and $q^{2}$-cyclotomic classes we give lower bounds on the minimum
distance.


title:
Anomalous diffusion limit of kinetic equations in spatially bounded
  domains

abstract:
  This paper is devoted to the anomalous diffusion limit of kinetic equations
with a fractional Fokker-Planck collision operator in a spatially bounded
domain. We consider two boundary conditions at the kinetic scale: absorption
and specular reflection. In the absorption case, we show that the long
time/small mean free path asymptotic dynamics are described by a fractional
diffusion equation with homogeneous Dirichlet-type boundary conditions set on
the whole complement of the spatial domain. On the other hand, specular
reflections will give rise to a new operator which we call specular diffusion
operator and write $(-\Delta)_{\text{SR}}^s$. This non-local diffusion operator
strongly depends on the geometry of the domain and includes in its definition
the interaction between the diffusion and the boundary. We consider two types
of domains: half-spaces and balls in $\mathbb{R}^d$. In these domains, we prove
properties of the specular diffusion operator and establish existence and
uniqueness of weak solutions to the associated heat-type equation.


title:
$\epsilon$-Expansion in Critical $\phi^3$-Theory on Real Projective
  Space from Conformal Field Theory

abstract:
  We use a compatibility between the conformal symmetry and the equations of
motion to solve the one-point function in the critical $\phi^3$-theory (a.k.a
the critical Lee-Yang model) on the $d = 6 - \epsilon$ dimensional real
projective space to the first non-trivial order in the $\epsilon$-expansion. It
reproduces the conventional perturbation theory and agrees with the numerical
conformal bootstrap result.


title: String point of view for heavy-light mesons

abstract:
  An approximate rotational symmetry of a heavy-light meson is viewed from a
string picture. Using a simple string configuration, we derive a formula,
$(M-m_c)^2=\pi\sigma L$, whose coefficient of the r.h.s. is just 1/2 of that of
a light meson with two light quarks. A numerical plot is obtained for $D$
mesons of experimental data as well as several theoretical models, which shows
good agreement with this formula.


title: Some results on the higher Abel jacobi map for open varieties

abstract:
  In this article, we study the infinitemisal invariant of the relative higher
Abel Jacobi map of a smooth open morphism. We give a generalization of a
theorem of Voisin to open varieties and higher Chow groups and as a corollary a
non vanishing criterion for the higher Abel Jacobi map of a general open smooth
hypersurface section of high degree of a smooth projective variety Y. On the
other side, using Nori connectness theorem, the image of the primitive part of
the higher Abel Jacobi map of a general open smooth hypersurface section of
high degree of a smooth projective variety Y is generated by the image of the
restriction of a primitive cycle on the corresponding affine subset of Y


title: Solitons and spin transport in graphene boundary

abstract:
  It is shown that in (2+1)-dimensional condensed matter systems, induced
gravitational Chern-Simons (CS) action can play a crucial role for coherent
spin transport in a finite geometry, provided zero-curvature condition is
satisfied on the boundary. The role of the resultant KdV solitons is
explicated. The fact that KdV solitons can pass through each other without
interference, represent 'resistanceless' spin transport.


title:
Obstructions for Compactness of Hankel Operators: Compactness
  Multipliers

abstract:
  We establish a connection between compactness of Hankel operators and
geometry of the underlying domain through compactness multipliers for the
$\overline{\partial}$-Neumann operator. In particular, we prove that any
compactness multiplier induces a compact Hankel operator. We also generalize
the notion of compactness multipliers to vector fields and matrices and then we
use this generalization to generate compact Hankel operators.


title:
Frustration induced one-dimensionality in the isosceles triangular
  antiferromagnetic lattice of $\delta$-(EDT-TTF-CONMe$_{2}$)$_{2}$AsF$_6$

abstract:
  The $1/4$-filled organic compound,
$\delta$-(EDT-TTF-CONMe$_{2}$)$_{2}$AsF$_6$ is a frustrated two-dimensional
triangular magnetic system as shown by high-frequency (111.2 and 222.4 GHz)
electron spin resonance (ESR) and structural data in the literature. The
material gradually orders antiferromagnetically below 40~K but some
magnetically disordered domains persist down to 4 K. We propose that in defect
free regions frustration prevents true magnetic order down to at least 4 K in
spite of the large first- and second-neighbor exchange interactions along
chains and between chains, respectively. The antiferromagnetic (AFM) order
gradually developing below 40 K nucleates around structural defects that
locally cancel frustration. Two antiferromagnetic resonance modes mapped in the
principal planes at 4~K are assigned to the very weakly interacting
one-dimensional molecular chains in antiferromagnetic regions.


title: Lorentz transformation from an elementary point of view

abstract:
  Elementary methods are used to examine some nontrivial mathematical issues
underpinning the Lorentz transformation. Its eigen-system is characterized
through the exponential of a $G$-skew symmetric matrix, underlining its
unconnectedness at one of its extremes (the hyper-singular case). A different
yet equivalent angle is presented through Pauli coding which reveals the
connection between the hyper-singular case and the shear map.


title: On the exponential of semi-infinite quasi-Toeplitz matrices

abstract:
  Let $a(z)=\sum_{i\in\mathbb Z}a_iz^i$ be a complex valued function defined
for $|z|=1$, such that $\sum_{i\in\mathbb Z}|ia_i|<\infty$, and let
$E=(e_{i,j})_{i,j\in\mathbb {Z}^+}$ be such that
$\sum_{i,j\in\mathbb{Z}^+}|e_{i,j}|<\infty$. A semi-infinite quasi-Toeplitz
matrix is a matrix of the kind $A=T(a)+E$, where
$T(a)=(t_{i,j})_{i,j\in\mathbb{Z}^+}$ is the semi-infinite Toeplitz matrix
associated with the symbol $a(z)$, that is, $t_{i,j}=a_{j-i}$ for
$i,j\in\mathbb Z^+$. We analyze theoretical and computational properties of the
exponential of $A$. More specifically, it is shown that $\exp(A)=T(\exp(a))+F$
where $F=(f_{i,j})_{i,j\in\mathbb{Z}^+}$ is such that
$\sum_{i,j\in\mathbb{Z}^+}|f_{i,j}|$ is finite, i.e., $\exp(A)$ is a
semi-infinite quasi-Toeplitz matrix as well, and an effective algorithm for its
computation is given. These results can be extended from the function $\exp(z)$
to any function $f(z)$ satisfying mild conditions, and can be applied to finite
quasi-Toeplitz matrices.


title: Change-point analysis in frequency domain for chronological data

abstract:
  The purpose of this study is to provide a new methodology of how one can
consistently estimate a change-point in time series data. In contrast with
previous studies, the suggested methodology employs only the empirical spectral
density and its first moment. This is accomplished when both the means and
variances before and after the unidentified time point are unknown. Then, the
well-known Gauss-Newton algorithm is applied to estimate and provide asymptotic
results for the parameters involved. Simulations carried out under different
distributions, sizes and unknown time points confirm the validity and accuracy
of the methodology. The real-world example considered in the paper illustrates
the robustness of the methodology in the presence of even extreme outliers.


title:
Investigating the rotational evolution of very low-mass stars and brown
  dwarfs in young clusters using Monte Carlo simulations

abstract:
  Context. Very low-mass (VLM) stars and brown dwarfs (BDs) present a different
rotational behaviour from their solar mass counter-parts. Aims. We investigate
the rotational evolution of young VLM stars and BDs using Monte Carlo
simulations under the hypothesis of disk locking and stellar angular momentum
conservation. Methods. We built a set of objects with masses ranging from 0.01
Mo to 0.4 Mo and considered models with single- and double- peaked initial
period distributions with and without disk locking. An object is considered to
be diskless when its mass accretion rate is below a given threshold. Results.
Models with initial single-peaked period distributions reproduce the
observations well given that BDs rotate faster than VLM stars. We observe a
correlation between rotational period and mass when we relax the disk locking
hypothesis, but with a shallower slope compared to some observational results.
The angular momentum evolution of diskless stars is flatter than it is for
stars with a disk which occurs because the moment of inertia of objects less
massive than 0.2 Mo remains pratically constant for a time scale that increases
with decreasing stellar mass. Conclusions. Comparing our results with the
available observational data we see that disk locking is not as important in
the low-mass regime and that the rotational behaviour of VLM stars and BDs is
different from what is seen in their solar mass counterparts.


title: On a generalized Fra\"iss\'e limit construction

abstract:
  In this paper, we present a slightly modified version of Fra\"iss\'e theory
which is used in a paper by Christopher J. Eagle, Ilijas Farah, Bradd Hart,
Boris Kadets, Vladyslav Kalashnyk and Martino Lupini (arXiv:1411.4066) and
another by the author (arXiv:1602.00124). Using this version, we also show that
every UHF algebra can be recognized as a Fra\"iss\'e limit of a class of
C*-algebras of matrix-valued continuous functions on cubes with distinguished
traces.


title:
All-optical cooling of Fermi gases via Pauli inhibition of spontaneous
  emission

abstract:
  A technique is proposed to cool Fermi gases to the regime of quantum
degeneracy based on the expected inhibition of spontaneous emission due to the
Pauli principle. The reduction of the linewidth for spontaneous emission
originates a corresponding reduction of the Doppler temperature, which under
specific conditions may give rise to a runaway process through which fermions
are progressively cooled. The approach requires a combination of a
magneto-optical trap as a cooling system and an optical dipole trap to enhance
quantum degeneracy. This results in expected Fermi degeneracy factors $T/T_F$
comparable to the lowest values recently achieved, with potential for a direct
implementation in optical lattices. The experimental demonstration of this
technique should also indirectly provide a macroscopic manifestation of the
Pauli exclusion principle at the atomic physics level.


title: On Embeddings of $\ell_1^k$ from Locally Decodable Codes

abstract:
  We show that any $q$-query locally decodable code (LDC) gives a copy of
$\ell_1^k$ with small distortion in the Banach space of $q$-linear forms on
$\ell_{p_1}^N\times\cdots\times\ell_{p_q}^N$, provided $1/p_1 + \cdots + 1/p_q
\leq 1$ and where $k$, $N$, and the distortion are simple functions of the code
parameters. We exhibit the copy of $\ell_1^k$ by constructing a basis for it
directly from "smooth" LDC decoders. Based on this, we give alternative proofs
for known lower bounds on the length of 2-query LDCs. Using similar techniques,
we reprove known lower bounds for larger $q$. We also discuss the relation with
an alternative proof, due to Pisier, of a result of Naor, Regev, and the author
on cotype properties of projective tensor products of $\ell_p$ spaces.


title:
Pressure-induced Topological Node-Line Semimetals in Alkaline-Earth
  Hexaborides XB6 (X=Ca, Sr, Ba)

abstract:
  Based on first-principles calculations, we reported that external pressure
can induce topological phase transition in alkaline-earth hexaborides, XB6
(X=Ca, Sr, Ba). It was revealed that XB6 is transformed from trivial
semiconductors to topological node-line semimetals under moderate pressures
when spin-orbit coupling (SOC) is ignored. The band inversion between B px (pz)
and py orbitals at X point is responsible for the formation of node-line
semimetals. Three node-line rings around X point are protected by the
combination of the time-reversal and spatial inversion symmetries, and the
drumhead surface bands are obtained in the interiors of the projected node-line
rings. When SOC is included, tiny gaps (< 4.8 meV) open at the crossing lines,
and the XB6 becomes strong topological insulators with Z2 indices (1;111). As
the SOC-induced gap opening is negligible, our findings thus suggest ideal real
systems for experimental exploration of the fundamental physics of topological
node-line semimetals.


title: Separating detection and catalog production

abstract:
  In the coming era of massive surveys (e.g. LSST, SKA), the role of the
database designers and the algorithms they choose to adopt becomes the decisive
factor in scientific progress. Systems that allow/encourage users/scientists to
be more creative with the reduction/analysis algorithms can greatly enhance
scientific productivity. The separation/modularity of the detection processes
and catalog production is one proposal for achieving `Reduction/analysis
algorithms for large databases and vice versa' (a key theme for the 26th
ADASS). With the new noise-based detection paradigm, non-parametric detection
is now possible for astronomical objects to very low surface brightness limits.
In our implementation, one software (NoiseChisel) is in charge of detection and
another (MakeCatalog) is in charge of catalog production. This modularity has
many advantages for pipeline developers, and more importantly, it empowers
scientific curiosity and creativity.


title: Finite and Infinite Nested Square Roots Convergent to Unity

abstract:
  We investigate finite and infinite nested square root formulas convergent to
unity.


title:
The Explicit Definition of Quantifiers via Hilbert's epsilon is
  Confluent and Terminating

abstract:
  We investigate the elimination of quantifiers in first-order formulas via
Hilbert's epsilon-operator (or -binder), following Bernays' explicit
definitions of the existential and the universal quantifier symbol by means of
epsilon-terms. This elimination has its first explicit occurrence in the proof
of the first epsilon-theorem in Hilbert-Bernays in 1939. We think that there is
a lacuna in this proof w.r.t. this elimination, related to the erroneous
assumption that explicit definitions always terminate. Surprisingly, to the
best of our knowledge, nobody ever proved confluence or termination for this
elimination procedure. Even myths on non-confluence and the openness of the
termination problem are circulating. We show confluence and termination of this
elimination procedure by means of a direct, straightforward, and easily
verifiable proof, based on a new theorem on how to obtain termination from weak
normalization.


title: Does the complex Langevin method give unbiased results?

abstract:
  We investigate whether the stationary solution of the Fokker-Planck equation
of the complex Langevin algorithm reproduces the correct expectation values.
When the complex Langevin algorithm for an action $S(x)$ is convergent, it
produces an equivalent complex probability distribution $P(x)$ which ideally
would coincide with $e^{-S(x)}$. We show that the projected Fokker-Planck
equation fulfilled by $P(x)$ may contain an anomalous term whose form is made
explicit. Such term spoils the relation $P(x)=e^{-S(x)}$, introducing a bias in
the expectation values. Through the analysis of several periodic and
non-periodic one-dimensional problems, using either exact or numerical
solutions of the Fokker-Planck equation on the complex plane, it is shown that
the anomaly is present quite generally. In fact, an anomaly is expected
whenever the Langevin walker needs only a finite time to go to infinity and
come back, and this is the case for typical actions. We conjecture that the
anomaly is the rule rather than the exception in the one-dimensional case,
however, this could change as the number of variables involved increases.


title:
Deep Residual Learning for Compressed Sensing CT Reconstruction via
  Persistent Homology Analysis

abstract:
  Recently, compressed sensing (CS) computed tomography (CT) using sparse
projection views has been extensively investigated to reduce the potential risk
of radiation to patient. However, due to the insufficient number of projection
views, an analytic reconstruction approach results in severe streaking
artifacts and CS-based iterative approach is computationally very expensive. To
address this issue, here we propose a novel deep residual learning approach for
sparse view CT reconstruction. Specifically, based on a novel persistent
homology analysis showing that the manifold of streaking artifacts is
topologically simpler than original ones, a deep residual learning architecture
that estimates the streaking artifacts is developed. Once a streaking artifact
image is estimated, an artifact-free image can be obtained by subtracting the
streaking artifacts from the input image. Using extensive experiments with real
patient data set, we confirm that the proposed residual learning provides
significantly better image reconstruction performance with several orders of
magnitude faster computational speed.


title:
Abstract key polynomials and comparison theorems with the key
  polynomials of Mac Lane -- Vaquie

abstract:
  Let $\iota:(K,\nu)\hookrightarrow(K(x),\mu)$ be a simple purely
transcendental extension of valued fields. In order to study such an extension,
M. Vaqui\'e, generalizing an earlier construction of S. Mac Lane, introduced
the notion of Key polynomials. In this paper we define a related notion of
\textbf{abstract key polynomials} associated to $\iota$ and study the
relationship between them and key polynomials of Mac Lane -- Vaqui\'e.
Associated to each abstract key polynomial $Q$, we define the truncation
$\mu_{Q}$ of $\mu$ with respect to $Q$ and we study the properties of those
truncations. Roughly speaking, $\mu_{Q}$ is an approximation to $\mu$ defined
by the key polynomial $Q$. We also define the notion of an abstract key
polynomial $Q'$ being an \textbf{immediate successor} of another abstract key
polynomial $Q$ (in this situation we write $Q<Q'$). The main comparison results
proved in this paper are as follows:(1): An abstract key polynomial for $\mu$
is a Mac Lane -- Vaqui\'e key polynomial for the truncated valuation
$\mu_{Q}$.(2): If $Q<Q'$ are two abstract key polynomials for $\mu$ then $Q'$
is a Mac Lane -- Vaqui\'e key polynomial for $\mu_{Q}$. (3) which, for a monic
polynomial $Q\in K[x]$ and a valuation $\mu'$ of $K(x)$, gives a sufficient
condition for $Q$ to be an abstract key polynomial for $\mu'$. Combined with an
earlier result of M. Vaqui\'e, this describes a class of pairs of valuations
$(\mu,\mu')$ such that $Q$ is a Mac Lane -- Vaqui\'e key polynomial for $\mu$
and an abstract key polynomial for $\mu'$.


title:
The relative exponential growth rate of subgroups of acylindrically
  hyperbolic groups

abstract:
  We introduce a new invariant of finitely generated groups, the ambiguity
function, and prove that every finitely generated acylindrically hyperbolic
group has a linearly bounded ambiguity function. We use this result to prove
that the relative exponential growth rate $\lim \limits_{n \rightarrow \infty}
\sqrt[n]{\vert B^{X}_H(n) \vert}$ of a subgroup $H$ of an acylindrically
hyperbolic group $G$ exists with respect to every finite generating set $X$ of
$G$, if $H$ contains a loxodromic element of $G$. Further we prove that the
relative exponential growth rate of every finitely generated subgroup $H$ of a
right-angled Artin group $A_{\Gamma}$ exists with respect to every finite
generating set of $A_{\Gamma}$.


title: On the Contact Numbers of Ball Packings on Various Hexagonal Grids

abstract:
  We describe the structure of the different hexagonal grids in dimension d=3,
propose short notation for them, investigate the contact numbers of ball
packings in these grids and share some computational results up to 200 balls,
using mainly the greedy algorithm. We consider the octahedral grid, too.


title:
Semantic tracking: Single-target tracking with inter-supervised
  convolutional networks

abstract:
  This article presents a semantic tracker which simultaneously tracks a single
target and recognises its category. In general, it is hard to design a tracking
model suitable for all object categories, e.g., a rigid tracker for a car is
not suitable for a deformable gymnast. Category-based trackers usually achieve
superior tracking performance for the objects of that specific category, but
have difficulties being generalised. Therefore, we propose a novel unified
robust tracking framework which explicitly encodes both generic features and
category-based features. The tracker consists of a shared convolutional network
(NetS), which feeds into two parallel networks, NetC for classification and
NetT for tracking. NetS is pre-trained on ImageNet to serve as a generic
feature extractor across the different object categories for NetC and NetT.
NetC utilises those features within fully connected layers to classify the
object category. NetT has multiple branches, corresponding to multiple
categories, to distinguish the tracked object from the background. Since each
branch in NetT is trained by the videos of a specific category or groups of
similar categories, NetT encodes category-based features for tracking. During
online tracking, NetC and NetT jointly determine the target regions with the
right category and foreground labels for target estimation. To improve the
robustness and precision, NetC and NetT inter-supervise each other and trigger
network adaptation when their outputs are ambiguous for the same image regions
(i.e., when the category label contradicts the foreground/background
classification). We have compared the performance of our tracker to other
state-of-the-art trackers on a large-scale tracking benchmark (100
sequences)---the obtained results demonstrate the effectiveness of our proposed
tracker as it outperformed other 38 state-of-the-art tracking algorithms.


title:
Studying the influence of inclusion characteristics on the
  characteristic length involved in quasi-brittle materials using the lattice
  element method

abstract:
  Unlike nonlocal models, there is no need to introduce an internal length in
the constitutive law for lattice model at the mesoscopic scale. Actually, the
internal length is not explicitly introduced but rather governed by the
mesostructure characteristics themselves. The influence of the mesostructure on
the width of the fracture process zone which is assumed to be correlated to the
characteristic length of the homogenized quasi-brittle material is studied. The
influence of the ligament size (a structural parameter) is also investigated.
This analysis provides recommendations/warnings when extracting an internal
length required for nonlocal damage models from the material mesostructure


title:
The contribution of dissolving star clusters to the population of
  ultra-faint objects in the outer halo of the Milky Way

abstract:
  In the last decade, several ultra faint objects (UFOs, $M_V\gtrsim-3.5$) have
been discovered in the outer halo of the Milky Way. For some of these objects
it is not clear whether they are star clusters or (ultra-faint) dwarf galaxies.
In this work we quantify the contribution of star clusters to the population of
UFOs. We extrapolated the mass and Galactocentric radius distribution of the
globular clusters using a population model, finding that the Milky Way contains
about $3.3^{+7.3}_{-1.6}$ star clusters with $M_V\gtrsim-3.5$ and
Galactocentric radius $\geq20\,$kpc. To understand whether dissolving clusters
can appear as UFOs, we run a suite of direct $N$-body models, varying the
orbit, the Galactic potential, the binary fraction and the black hole (BH)
natal kick velocities. In the analyses, we consider observational biases such
as: luminosity limit, field stars, and line-of-sight projection. We find that
star clusters contribute to both the compact and the extended population of
UFOs: clusters without BHs appear compact with radii $\sim5\,$pc, while
clusters that retain their BHs after formation have radii $\gtrsim20\,$pc. The
properties of the extended clusters are remarkably similar to those of dwarf
galaxies: high inferred mass-to-light ratios due to binaries; binary properties
mildly affected by dynamical evolution; no observable mass segregation; and
flattened stellar mass function. We conclude that the slope of the stellar mass
function as a function of Galactocentric radius and the presence/absence of
cold streams can discriminate between DM free and DM dominated UFOs.


title: Sumsets of the distance set in $\mathbb{F}_q^d$

abstract:
  Let $\mathbb{F}_q$ be a finite field of order $q$, where $q$ is large odd
prime power. In this paper, we improve some recent results on the additive
energy of the distance set, and on sumsets of the distance set due to
Shparlinski (2016). More precisely, we prove that for $\mathcal{E}\subseteq
\mathbb{F}_q^d$, if $d=2$ and $q^{1+\frac{1}{4k-1}}=o(|\mathcal{E}|)$ then we
have $|k\Delta_{\mathbb{F}_q}(\mathcal{E})|=(1-o(1))q$; if $d\ge 3$ and
$q^{\frac{d}{2}+\frac{1}{2k}}=o(|\mathcal{E}|)$ then we have
$|k\Delta_{\mathbb{F}_q}(\mathcal{E})|=(1-o(1))q,$ where
$k\Delta_{\mathbb{F}_q}(\mathcal{E}):=\Delta_{\mathbb{F}_q}(\mathcal{E})+\cdots+\Delta_{\mathbb{F}_q}(\mathcal{E})
~(\mbox{$k$ times}).$


title: Fractional Gaussian noise: Prior specification and model comparison

abstract:
  Fractional Gaussian noise (fGn) is a self-similar stochastic process used to
model anti-persistent or persistent dependency structures in observed time
series. Properties of the autocovariance function of fGn are characterised by
the Hurst exponent (H), which in Bayesian contexts typically has been assigned
a uniform prior on the unit interval. This paper argues why a uniform prior is
unreasonable and introduces the use of a penalised complexity (PC) prior for H.
The PC prior is computed to penalise divergence from the special case of white
noise, and is invariant to reparameterisations. An immediate advantage is that
the exact same prior can be used for the autocorrelation coefficient of a
first-order autoregressive process AR(1), as this model also reflects a
flexible version of white noise. Within the general setting of latent Gaussian
models, this allows us to compare an fGn model component with AR(1) using Bayes
factors, avoiding confounding effects of prior choices for the hyperparameters.
Among others, this is useful in climate regression models where inference for
underlying linear or smooth trends depends heavily on the assumed noise model.


title: The puzzle of the CNO isotope ratios in AGB carbon stars

abstract:
  Previous determinations of the oxygen isotopic ratios in AGB carbon stars
were at odds with the existing theoretical predictions. We aim to redetermine
the oxygen ratios in these stars using new spectral analysis tools and further
develop discussions on the carbon and nitrogen isotopic ratios in order to
elucidate this problem. Oxygen isotopic ratios were derived from spectra in the
K-band in a sample of galactic AGB carbon stars of different spectral types and
near solar metallicity. Synthetic spectra calculated in LTE with spherical
carbon-rich atmosphere models and updated molecular line lists were used. The
CNO isotope ratios derived in a homogeneous way, were compared with theoretical
predictions for low-mass (1.5-3 M_o) AGB stars computed with the FUNS code
assuming extra mixing both during the RGB and AGB phases. For most of the stars
the 16O/17O/18O ratios derived are in good agreement with theoretical
predictions confirming that, for AGB stars, are established using the values
reached after the FDU according to the initial stellar mass. This fact, as far
as the oxygen isotopic ratios are concerned, leaves little space for the
operation of any extra mixing mechanism during the AGB phase. Nevertheless, for
a few stars with large 16O/17O/18O, the operation of such a mechanism might be
required, although their observed 12C/13C and 14N/15N ratios would be difficult
to reconcile within this scenario. Furthermore, J-type stars tend to have lower
16O/17O ratios than the normal carbon stars, as already indicated in previous
studies. Excluding these peculiar stars, AGB carbon stars occupy the same
region as pre-solar type I oxide grains in a 17O/16O vs. 18O/16O diagram,
showing little spread. This reinforces the idea that these grains were probably
formed in low-mass stars during the previous O-rich phases.


title:
Recursive Relationships in the Classes of Odd Graphs and Middle Levels
  Graphs

abstract:
  The classes of odd graphs $O_n$ and middle levels graphs $B_n$ form one
parameter subclasses of the Kneser graphs and bipartite Kneser graphs
respectively. In particular both classes are vertex transitive while resisting
definitive conclusions about their Hamiltonicity, and have thus come under
scrutiny with regards to the Lov\'asz conjecture. In this paper, we will
establish that middle levels graphs may always be embedded in odd graphs and
middle levels graphs of higher degree, and furthermore, that this embedding
allows us to define a recursion relationship in both classes which can be used
to lift paths in $O_{n-1}$ (respectively $B_{n-1}$) to paths in $O_n$
(respectively $B_n$). This embedding also gives rise to the natural formation
of a class of biregular graphs which give connections between the odd graphs,
middle levels graphs and Catalan numbers.


title: Connectivity and $W_v$-Paths in Polyhedral Maps on Surfaces

abstract:
  The $W_v$-Path Conjecture due to Klee and Wolfe states that any two vertices
of a simple polytope can be joined by a path that does not revisit any facet.
This is equivalent to the well-known Hirsch Conjecture. Klee proved that the
$W_v$-Path Conjecture is true for all 3-polytopes (3-connected plane graphs),
and conjectured even more, namely that the $W_v$-Path Conjecture is true for
all general cell complexes. This general $W_v$-Path Conjecture was verified for
polyhedral maps on the projective plane and the torus by Barnette, and on the
Klein bottle by Pulapaka and Vince. Let $G$ be a graph polyhedrally embedded in
a surface $\Sigma$, and $x, y$ be two vertices of $G$. In this paper, we show
that if there are three internally disjoint $(x,y)$-paths which are homotopic
to each other, then there exists a $W_v$-path joining $x$ and $y$. For every
surface $\Sigma$, define a function $f(\Sigma)$ such that if for every graph
polyhedrally embedded in $\Sigma$ and for a pair of vertices $x$ and $y$ in
$V(G)$, the local connectivity $\kappa_G(x,y) \ge f(\Sigma)$, then there exists
a $W_v$-path joining $x$ and $y$. We show that $f(\Sigma)=3$ if $\Sigma$ is the
sphere, and for all other surfaces $3-\tau(\Sigma)\le f(\Sigma)\le
9-4\chi(\Sigma)$, where $\chi(\Sigma)$ is the Euler characteristic of $\Sigma$,
and $\tau(\Sigma)=\chi(\Sigma)$ if $\chi(\Sigma)< -1$ and 0 otherwise. Further,
if $x$ and $y$ are not cofacial, we prove that $G$ has at least
$\kappa_G(x,y)+4\chi(\Sigma)-8$ internally disjoint $W_v$-paths joining $x$ and
$y$. This bound is sharp for the sphere. Our results indicate that the
$W_v$-path problem is related to both the local connectivity $\kappa_G(x,y)$,
and the number of different homotopy classes of internally disjoint
$(x,y)$-paths as well as the number of internally disjoint $(x,y)$-paths in
each homotopy class.


title: Deep Outdoor Illumination Estimation

abstract:
  We present a CNN-based technique to estimate high-dynamic range outdoor
illumination from a single low dynamic range image. To train the CNN, we
leverage a large dataset of outdoor panoramas. We fit a low-dimensional
physically-based outdoor illumination model to the skies in these panoramas
giving us a compact set of parameters (including sun position, atmospheric
conditions, and camera parameters). We extract limited field-of-view images
from the panoramas, and train a CNN with this large set of input image--output
lighting parameter pairs. Given a test image, this network can be used to infer
illumination parameters that can, in turn, be used to reconstruct an outdoor
illumination environment map. We demonstrate that our approach allows the
recovery of plausible illumination conditions and enables photorealistic
virtual object insertion from a single image. An extensive evaluation on both
the panorama dataset and captured HDR environment maps shows that our technique
significantly outperforms previous solutions to this problem.


title:
Supersolid and pair correlations of the extended Jaynes-Cummings-Hubbard
  model on triangular lattices

abstract:
  We study the extended Jaynes-Cummings-Hubbard model on triangular cavity
lattices and zigzag ladders. By using density-matrix renormalization group
methods, we observe various types of solids with different density patterns and
find evidence for light supersolids, which exist in extended regions of the
phase diagram of the zigzag ladder. Furthermore, we observe strong pair
correlations in the supersolid phase due to the interplay between the atoms in
the cavities and atom-photon interaction. By means of cluster mean-field
simulations and a scaling of the cluster size extending our analysis to
two-dimensional triangular lattices, we present evidence for the emergence of a
light supersolid in this case also.


title:
The second generalized Hamming weight of some evaluation codes arising
  from a projective torus

abstract:
  In this paper we find the second generalized Hamming weight of some
evaluation codes arising from a projective torus, and it allows to compute the
second generalized Hamming weight of the codes parameterized by the edges of
any complete bipartite graph. Also, at the beginning, we obtain some results
about the generalized Hamming weights of some evaluation codes arising from a
complete intersection when the minimum distance is known and they are
non--degenerate codes. Finally we give an example where we use these results to
determine the complete weight hierarchy of some codes.


title: On Functions of quasi Toeplitz matrices

abstract:
  Let $a(z)=\sum_{i\in\mathbb Z}a_iz^i$ be a complex valued continuous
function, defined for $|z|=1$, such that
$\sum_{i=-\infty}^{+\infty}|ia_i|<\infty$. Consider the semi-infinite Toeplitz
matrix $T(a)=(t_{i,j})_{i,j\in\mathbb Z^+}$ associated with the symbol $a(z)$
such that $t_{i,j}=a_{j-i}$. A quasi-Toeplitz matrix associated with the
continuous symbol $a(z)$ is a matrix of the form $A=T(a)+E$ where
$E=(e_{i,j})$, $\sum_{i,j\in\mathbb Z^+}|e_{i,j}|<\infty$, and is called a
CQT-matrix. Given a function $f(x)$ and a CQT matrix $M$, we provide conditions
under which $f(M)$ is well defined and is a CQT matrix. Moreover, we introduce
a parametrization of CQT matrices and algorithms for the computation of $f(M)$.
We treat the case where $f(x)$ is assigned in terms of power series and the
case where $f(x)$ is defined in terms of a Cauchy integral. This analysis is
applied also to finite matrices which can be written as the sum of a Toeplitz
matrix and of a low rank correction.


title:
Interplay between endogenous and exogenous fluctuations in financial
  markets

abstract:
  We address microscopic, agent based, and macroscopic, stochastic, modeling of
the financial markets combining it with the exogenous noise. The interplay
between the endogenous dynamics of agents and the exogenous noise is the
primary mechanism responsible for the observed long-range dependence and
statistical properties of high volatility return intervals. By exogenous noise
we mean information flow or/and order flow fluctuations. Numerical results
based on the proposed model reveal that the exogenous fluctuations have to be
considered as indispensable part of comprehensive modeling of the financial
markets.


title:
The Classification Permutation Test: A Nonparametric Test for Equality
  of Multivariate Distributions

abstract:
  The gold standard for identifying causal relationships is a randomized
controlled experiment. In many applications in the social sciences and
medicine, the researcher does not control the assignment mechanism and instead
may rely upon natural experiments, regression discontinuity designs, RCTs with
attrition, or matching methods as a substitute to experimental randomization.
The standard testable implication of random assignment is covariate balance
between the treated and control units. Covariate balance is therefore commonly
used to validate the claim of "as-if" random assignment. We develop a new
nonparametric test of covariate balance. Our Classification Permutation Test
(CPT) is based on a combination of classification methods (e.g. logistic
regression or random forests) with Fisherian permutation inference. The CPT is
guaranteed to have correct coverage and is consistent under weak assumptions on
the chosen classifier. To illustrate the gains of using the CPT, we revisit
four real data examples: Lyall (2009); Green and Winik (2010); Eggers and
Hainmueller (2009); and Rouse (1995). Monte Carlo power simulations are used to
compare the CPT to two existing nonparametric tests of equality of multivariate
distributions.


title:
Diagnostics of many-particle electronic states from non-stationary
  currents and residual charge

abstract:
  We propose the method for identifying many particle electronic states in the
system of coupled quantum dots (impurities) with Coulomb correlations. We
demonstrate that different electronic states can be distinguished by the
complex analysis of localized charge dynamics and non-stationary
characteristics. We show that localized charge time evolution strongly depends
on the properties of initial state and analyze different time scales in charge
kinetics for initially prepared singlet and triplet states. We reveal the
conditions for existence of charge trapping effects governed by the selection
rules for electron transitions between the states with different occupation
numbers.


title: Spatially-indirect Exciton Condensate Phases in Double Bilayer Graphene

abstract:
  We present a theory of spatially indirect exciton condensate states in
systems composed of a pair of electrically isolated Bernal graphene bilayers.
The ground state phase diagram in a two-dimensional
displacement-field/inter-bilayer-bias space includes layer-polarized
semiconductors, spin-density-wave states, exciton condensates, and states with
mixed excitonic and spin order. We find that two different condensate states,
distinguished by a chirality index, are stable under different electrical
control conditions.


title: Reductions of abelian varieties of generalized Mumford type

abstract:
  We study the special fibers of a certain class of absolutely simple abelian
varieties over number fields with endomorphism rings $\bz$ and possessing
$l$-adic monodromy groups of the least possible rank. We also study the
Dirichlet density of the places at which the possible reductions occur and
confirm a special case of a broader conjecture for the splitting of reductions
of abelian varieties over number fields.


title:
Analytic Calculation of Radio Emission from Extensive Air Showers
  subjected to Atmospheric Electric Fields

abstract:
  We have developed a code that semi-analytically calculates the radio
footprint (intensity and polarization) of an extensive air shower subject to
atmospheric electric fields. This can be used to reconstruct the height
dependence of atmospheric electric field from the measured radio footprint. The
various parameterizations of the spatial extent of the induced currents are
based on the results of Monte-Carlo shower simulations. The calculated radio
footprints agree well with microscopic CoREAS simulations.


title:
Formalizing Multi-Agent Systems Using Action Descriptions in Single
  Agent Perspective

abstract:
  Logic-based representations of multi-agent systems have been extensively
studied. In this work, we focus on the action language BC to formalize global
views of MAS domains. Methodologically, we start representing the behaviour of
each agent by an action description from a single agent perspective. Then, it
goes through two stages that guide the modeler in composing the global view by
first designating multi-agent aspects of the domain via potential conflicts and
later resolving these conflicts according to the expected behaviour of the
overall system. Considering that representing single agent descriptions is
relatively simpler than representing multi-agent description directly, the
formalization developed here is valuable from a knowledge representation
perspective.


title: An upper bound for weak $B_k$-sets

abstract:
  We prove that if $A\subseteq \{ 1,2,\dots, N \}$ does not contain any
solution to the equation $x_1+\dots+x_k=y_1+\dots+y_k$ with distinct
$x_1,\dots,x_k,y_1,\dots,y_k\in A$, then $|A|\ll {k^{3/2}}N^{1/k}.$


title: On the ill posedness of Force-Free Electrodynamics in Euler Potentials

abstract:
  We prove that the initial value problem for Force-free Electrodynamics in
Euler variables is not well posed. We establish this result by showing that a
well-posedness criterion provided by Kreiss fails to hold for this theory, and
using a theorem provided by Strang. To show the nature of the problem we
display a particular bounded (in Sobolev norms) sequence of initial data for
the Force-free equations such that at any given time as close to zero as one
wishes, the corresponding evolution sequence is not bounded. Thus, the
Force-free evolution is non continuous in that norm with respect to the initial
data. We furthermore prove that this problem is also ill-posed in the
Leray-Ohya sense.


title: Taming active turbulence with patterned soft interfaces

abstract:
  Active matter embraces systems that self-organize at different length and
time scales, often exhibiting turbulent flows. Here, we use a
quasi-two-dimensional nematically ordered layer of a protein-based active gel
to experimentally demonstrate that the geometry of active flows, which we have
characterized by means of the statistical distribution of eddy sizes, can be
reversibly modified. To this purpose, the active material is prepared in
contact with a thermotropic liquid crystal, whose lamellar smectic-A phase
tiles the water/oil interface with a lattice of anisotropic domains that
feature circular easy-flow directions. The active flow, which arises from the
motion of parabolic folds within the filamentous active material, becomes
effectively confined into circulating eddies that are in registry with the
underlying smectic-A domains. Based on topological arguments applied to the
circular confinement, together with well-known properties of the active
material, we show that the structure of the active flow is determined by a
single intrinsic length scale. The role of this length scale thus reemerges
from setting the decay length in the exponential eddy size distribution of the
free turbulent regime, to determining the minimum size of circulating eddies
featuring a scale-free power law. Our results demonstrate that soft-confinement
provides with an invaluable tool to probe the intrinsic length and time scales
of active materials, and pave the way for further exploration looking for
similarities and differences between active and passive two-dimensional
turbulence.


title: Discover Aggregates Exceptions over Hidden Web Databases

abstract:
  Nowadays, many web databases "hidden" behind their restrictive search
interfaces (e.g., Amazon, eBay) contain rich and valuable information that is
of significant interests to various third parties. Recent studies have
demonstrated the possibility of estimating/tracking certain aggregate queries
over dynamic hidden web databases. Nonetheless, tracking all possible aggregate
query answers to report interesting findings (i.e., exceptions), while still
adhering to the stringent query-count limitations enforced by many hidden web
databases providers, is very challenging. In this paper, we develop a novel
technique for tracking and discovering exceptions (in terms of sudden changes
of aggregates) over dynamic hidden web databases. Extensive real-world
experiments demonstrate the superiority of our proposed algorithms over
baseline solutions.


title: New bounds on the vertex Folkman number $F_v(2, 2, 2, 3; 4)$

abstract:
  For a graph $G$ the expression $G \overset{v}{\rightarrow} (a_1, ..., a_s)$
means that for every coloring of the vertices of $G$ in $s$ colors there exists
$i \in \{1, ..., s\}$ such that there is a monochromatic $a_i$-clique of color
$i$. The vertex Folkman number $F_v(a_1, ..., a_s; q)$ is defined as $$F_v(a_1,
..., a_s; q) = \min\{\vert V(G) \vert : G \overset{v}{\rightarrow} (a_1, ...,
a_s) \mbox{ and } K_q \not\subseteq G\}.$$ In this paper we improve the known
bounds on the number $F_v(2, 2, 2, 3; 4)$ by proving with the help of a
computer that $20 \leq F_v(2, 2, 2, 3; 4) \leq 22$.