title: Disordered Hyperuniform Heterogeneous Materials

abstract:
  Disordered hyperuniform many-body systems are distinguishable states of
matter that lie between a crystal and liquid: they are like perfect crystals in
the way they suppress large-scale density fluctuations and yet are like liquids
or glasses in that they are statistically isotropic with no Bragg peaks. These
systems play a vital role in a number of fundamental and applied problems:
glass formation, jamming, rigidity, photonic and electronic band structure,
localization of waves and excitations, self-organization, fluid dynamics,
quantum systems, and pure mathematics. systems. Here, we derive new rigorous
criteria that disordered hyperuniform two-phase heterogeneous materials must
obey and explore their consequences. Two-phase heterogeneous media are
ubiquitous, examples include composites and porous media, biological media,
foams, polymer blends, granular media, cellular solids, and colloids. We
rigorously establish the requirements for sphere packings to be
"multihyperuniform." We apply realizability conditions for an autocovariance
function and its associated spectral density of a two-phase medium, and then
incorporate hyperuniformity as a constraint in order to derive new conditions.
We show that some functional forms can immediately be eliminated from
consideration and identify other forms that are allowable. Specific examples
and counterexamples are described. Contact is made with well-known
microstructural models as well as irregular phase-separation and Turing-type
patterns. We also ascertain a family of spectral densities that are realizable
by disordered hyperuniform two-phase media in any space dimension, and present
explicit constructions. These studies provide insight into the nature of
disordered hyperuniformity in the context of heterogeneous materials and have
implications for the design of such novel amorphous materials.


title:
Anisotropic physical properties and pressure dependent magnetic ordering
  of CrAuTe$_4$

abstract:
  Systematic measurements of temperature dependent magnetization, resistivity
and angle-resolved photoemission spectroscopy (ARPES) at ambient pressure as
well as resistivity under pressures up to 5.25 GPa were conducted on single
crystals of CrAuTe$_4$. Magnetization data suggest that magnetic moments are
aligned antiferromagnetically along the crystallographic $c$-axis below
$T_\textrm{N}$ = 255 K. ARPES measurements show band reconstruction due to the
magnetic ordering. Magnetoresistance data show clear anisotropy, and, at high
fields, quantum oscillations. The Neel temperature decreases monotonically
under pressure, decreasing to $T_\textrm{N}$ = 236 K at 5.22 GPa. The pressure
dependencies of (i) $T_\textrm{N}$, (ii) the residual resistivity ratio, and
(iii) the size and power-law behavior of the low temperature magnetoresistance
all show anomalies near 2 GPa suggesting that there may be a phase transition
(structural, magnetic, and/or electronic) induced by pressure. For pressures
higher than 2 GPa a significantly different quantum oscillation frequency
emerges, consistent with a pressure induced change in the electronic states.


title: Robsut Wrod Reocginiton via semi-Character Recurrent Neural Network

abstract:
  Language processing mechanism by humans is generally more robust than
computers. The Cmabrigde Uinervtisy (Cambridge University) effect from the
psycholinguistics literature has demonstrated such a robust word processing
mechanism, where jumbled words (e.g. Cmabrigde / Cambridge) are recognized with
little cost. On the other hand, computational models for word recognition (e.g.
spelling checkers) perform poorly on data with such noise. Inspired by the
findings from the Cmabrigde Uinervtisy effect, we propose a word recognition
model based on a semi-character level recurrent neural network (scRNN). In our
experiments, we demonstrate that scRNN has significantly more robust
performance in word spelling correction (i.e. word recognition) compared to
existing spelling checkers and character-based convolutional neural network.
Furthermore, we demonstrate that the model is cognitively plausible by
replicating a psycholinguistics experiment about human reading difficulty using
our model.


title:
Properties of an ultrarelativistic charged particle radiation in a
  constant homogeneous crossed electromagnetic field

abstract:
  The properties of radiation created by a classical ultrarelativistic scalar
charged particle in a constant homogeneous crossed electromagnetic field are
described both analytically and numerically with radiation reaction taken into
account in the form of the Landau-Lifshitz equation. The total radiation
naturally falls into two parts: the radiation formed at the entrance point of a
particle into the crossed field (the synchrotron entrance radiation), and the
radiation coming from the late-time asymptotics of a particle motion (the
de-excited radiation). The synchrotron entrance radiation resembles, although
does not coincide with, the ultrarelativistic limit of the synchrotron
radiation: its distribution over energies and angles possesses almost the same
properties. The de-excited radiation is soft, not concentrated in the plane of
motion of a charged particle, and almost completely circularly polarized. The
photon energy delivering the maximum to its spectral angular distribution
decreases with increasing the initial energy of a charged particle, while the
maximum value of this distribution remains the same at the fixed observation
angle. The ultraviolet and infrared asymptotics of the total radiation are also
described.


title: Multivariate polynomial approximation in the hypercube

abstract:
  A theorem is proved concerning approximation of analytic functions by
multivariate polynomials in the $s$-dimensional hypercube. The geometric
convergence rate is determined not by the usual notion of degree of a
multivariate polynomial, but by the {\it Euclidean degree,} defined in terms of
the 2-norm rather than the 1-norm of the exponent vector $\bf k$ of a monomial
$x_1^{k_1}\cdots \kern .8pt x_s^{k_s}$.


title: Fermion number anomaly with the fluffy mirror fermion

abstract:
  Quite recently, Grabowska and Kaplan presented a 4-dimensional lattice
formulation of chiral gauge theories based on the chiral overlap operator. We
study this formulation from the perspective of the fermion number anomaly and
possible associated phenomenology. A simple argument shows that the consistency
of the formulation implies that the fermion with the opposite chirality to the
physical one, the "fluffy mirror fermion" or "fluff", suffers from the fermion
number anomaly in the same magnitude (with the opposite sign) as the physical
fermion. This immediately shows that if at least one of the fluff quarks is
massless, the formulation provides a simple viable solution to the strong CP
problem. Also, if the fluff interacts with gravity essentially in the same way
as the physical fermion, the formulation can realize the asymmetric dark matter
scenario.


title:
Phase-field modeling of isothermal quasi-incompressible multicomponent
  liquids

abstract:
  In this paper general dynamic equations describing the time evolution of
isothermal quasi-incompressible multicomponent liquids are derived in the
framework of the classical Ginzburg-Landau theory of first order phase
transformations. Based on the fundamental {equations of continuum mechanics}, a
general convection-diffusion dynamics is set up first for compressible liquids.
The constitutive relations for the diffusion fluxes and the capillary stress
are determined in the framework of gradient theories. {Next the general
definition of incompressibility is given}, which is taken into account {in the
derivation} by using the Lagrange multiplier method. To validate the theory,
the dynamic equations are solved numerically for the quaternary
quasi-incompressible Cahn-Hilliard system. It is demonstrated that variable
density (i) has no effect on equilibrium (in case of a suitably constructed
free energy functional), {and (ii) can} influence non-equilibrium pattern
formation significantly.


title: On eigenvalue bounds for a general class of Sturm-Liouville operators

abstract:
  We consider Sturm-Liouville operators with measure-valued weight and
potential, and positive, bounded diffusion coefficient which is bounded away
from zero. By means of a local periodicity condition, which can be seen as a
quantitative Gordon condition, we prove a bound on eigenvalues for the
corresponding operator in $L_p$, for $1\leq p<\infty$. We also explain the
sharpness of our quantitative bound, and provide an example for quasiperiodic
operators.


title: The abelianization of inverse limits of groups

abstract:
  The abelianization is a functor from groups to abelian groups, which is left
adjoint to the inclusion functor. Being a left adjoint, the abelianization
functor commutes with all small colimits. In this paper we investigate the
relation between the abelianization of a limit of groups and the limit of their
abelianizations. We show that if $\mathcal{T}$ is a countable directed poset
and $G:\mathcal{T}\longrightarrow\mathcal{G} rp$ is a diagram of groups that
satisfies the Mittag-Leffler condition, then the natural map
$$\mathrm{Ab}(\lim_{t\in\mathcal{T}}G_t)\longrightarrow\lim_{t\in\mathcal{T}}\mathrm{Ab}(G_t)$$
is surjective, and its kernel is a cotorsion group. In the special case of a
countable product of groups, we show that the Ulm length of the kernel does not
exceed $\aleph_1$.


title: Quantile based global sensitivity measures

abstract:
  New global sensitivity measures based on quantiles of the output are
introduced. Such measures can be used for global sensitivity analysis of
problems in which quantiles are explicitly the functions of interest and for
identification of variables which are the most important in achieving extreme
values of the model output. It is proven that there is a link between
introduced measures and Sobol main effect sensitivity indices. Two different
Monte Carlo estimators are considered. It is shown that the double loop
reordering approach is much more efficient than the brute force estimator.
Several test cases and practical case studies related to structural safety are
used to illustrate the developed method. Results of numerical calculations show
the efficiency of the presented technique.


title: The Logic of Resources and Capabilities

abstract:
  We introduce the logic LRC, designed to describe and reason about agents'
abilities and capabilities in using resources. The proposed framework bridges
two - up to now - mutually independent strands of literature: the one on logics
of abilities and capabilities, developed within the theory of agency, and the
one on logics of resources, motivated by program semantics. The logic LRC is
suitable to describe and reason about key aspects of social behaviour in
organizations. We prove a number of properties enjoyed by LRC (soundness,
completeness, canonicity, disjunction property) and its associated analytic
calculus (conservativity, cut elimination and subformula property). These
results lay at the intersection of the algebraic theory of unified
correspondence and the theory of multi-type calculi in structural proof theory.
Case studies are discussed which showcase several ways in which this framework
can be extended and enriched while retaining its basic properties, so as to
model an array of issues, both practically and theoretically relevant, spanning
from planning problems to the logical foundations of the theory of
organizations.


title: On the generalized Springer correspondence

abstract:
  We close a gap in the explicit determination of the generalized Springer
correspondence for a connected reductive group in good characteristic.


title:
Time-inhomogeneous fractional Poisson processes defined by the
  multistable subordinator

abstract:
  The space-fractional and the time-fractional Poisson processes are two
well-known models of fractional evolution. They can be constructed as standard
Poisson processes with the time variable replaced by a stable subordinator and
its inverse, respectively. The aim of this paper is to study non-homogeneous
versions of such models, which can be defined by means of the so-called
multistable subordinator (a jump process with non-stationary increments),
denoted by H. Firstly, we consider the Poisson process time-changed by H and we
obtain its explicit distribution and governing equation. Then, by using the
right-continuous inverse of H, we define an inhomogeneous analogue of the
time-fractional Poisson process.


title: Search for Compact Stellar Groups in the Vicinity of IRAS Sources

abstract:
  The results of a search for compact clusters in the vicinity of 19 IRAS
sources based on data from the GPS UKIDSS and Spitzer GLIMPSE surveys are
presented. Overall, clusters have been identified in 15 regions. Clusters are
identified for the first time in 4 regions (IRAS 18151-1208, IRAS 18316-0602,
18517+0437, 19110+1045). In 5 regions (IRAS 05168+3634, 05358+3543, IRAS
18507+0121, IRAS 20188+3928, IRAS 20198+3716) the compact groups we have
identified are substructures within more extended clusters. The radii of the
identified groups and the surface star density are widely scattered with ranges
of 0.3-2.7 pc and 4-1360 stars/pc^2, respectively. In 11 of the clusters, the
IRAS sources are associated with a pair or even a group of YSOs. The groups
identified in the near IR include representatives of a later evolutionary class
II among the stellar objects associated with the IRAS sources.


title: Imaging Electron Motion in Graphene

abstract:
  Research in semiconductor physics has advanced to the study of
two-dimensional (2D) materials where the surface controls electronic transport.
A scanning probe microscope (SPM) is an ideal tool to image electronic motion
in these devices by using the SPM tip as a scanning gate. In prior work for a
two dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure, a number
of phenomena were imaged, including electron flow from a quantum point contact,
and tuning of a few electron quantum dot. This approach was also used to study
InAs quantum dots grown in a InAs/InP nanowire heterostructure. New
two-dimensional materials such as graphene show great promise for fundamental
research and applications. We have extended or prior work to image the motion
of electrons along cyclotron orbits in single atomic layer graphene passing
from one point contact to a second point contact on the first magnetic focusing
peak in graphene. The charged SPM tip defects electrons passing from one
contact to the other, changing the conductance. A plot of the change in
conductance vs. tip position presents an image of electron flow. A low
temperature Scanning Capacitance Microscope (SCM) with a sensitive charge
preamplifier located near the SPM tip achieves a charge noise level 0.13
e/Hz1/2 with high spatial resolution 100 nm, which promises to be useful to
study electronic behavior in nanoscale devices.


title:
A Parallelizable Dual Smoothing Method for Large Scale Convex Regression
  Problems

abstract:
  Convex regression (CR) is an approach for fitting a convex function to a
finite number of observations. It arises in various applications from diverse
fields such as statistics, operations research, economics, and electrical
engineering. The least squares (LS) estimator, which can be computed via
solving a quadratic program (QP), is an intuitive method for convex regression
with already established strong theoretical guarantees. On the other hand,
since the number of constraints in the QP formulation increases quadratically
in the number of observed data points, the QP quickly becomes impractical to
solve using traditional interior point methods. To address this issue, we
propose a first-order method based on dual smoothing that carefully manages the
memory usage through parallelization in order to efficiently compute the LS
estimator in practice for large-scale CR instances.


title: Further investigations on a question of Zhang and L\"u

abstract:
  In the paper based on the question of Zhang and L\"u [15], we present one
theorem which will improve and extend results of Banerjee-Majumder [2] and a
recent result of Li-Huang [9].


title: Towards the Self-constructive Brain: emergence of adaptive behavior

abstract:
  Adaptive behavior is mainly the result of adaptive brains. We go a step
beyond and claim that the brain does not only adapt to its surrounding reality
but rather, it builds itself up to constructs its own reality. That is, rather
than just trying to passively understand its environment, the brain is the
architect of its own reality in an active process where its internal models of
the external world frame how its new interactions with the environment are
assimilated. These internal models represent relevant predictive patterns of
interaction all over the different brain structures: perceptual, sensorimotor,
motor, etc. The emergence of adaptive behavior arises from this
self-constructive nature of the brain, based on the following principles of
organization: self-experimental, self- growing, and self-repairing.
Self-experimental, since to ensure survival, the self-constructive brain (SCB)
is an active machine capable of performing experiments of its own interactions
with the environment by mental simulation. Self-growing, since it dynamically
and incrementally constructs internal structures in order to build a model of
the world as it gathers statistics from its interactions with the environment.
Self-repairing, since to survive the SCB must also be robust and capable of
finding ways to repair parts of previously working structures and hence
re-construct a previous relevant pattern of activity.


title: Spin-orbit coupling in Fe-based superconductors

abstract:
  We study the spin resonance peak in recently discovered iron-based
superconductors. The resonance peak observed in inelastic neutron scattering
experiments agrees well with predicted results for the extended $s$-wave
($s_\pm$) gap symmetry. Recent neutron scattering measurements show that there
is a disparity between longitudinal and transverse components of the dynamical
spin susceptibility. Such breaking of the spin-rotational invariance in the
spin-liquid phase can occur due to spin-orbit coupling. We study the role of
the spin-orbit interaction in the multiorbital model for Fe-pnictides and show
how it affects the spin resonance feature.


title:
Directed Flow of Charm Quarks as a Witness of the Initial Strong
  Magnetic Field in Ultra-Relativistic Heavy Ion Collisions

abstract:
  Ultra-relativistic Heavy-Ion Collision (HIC) generates very strong initial
magnetic field ($\vec B$) inducing a vorticity in the reaction plane. The high
$\vec{B}$ influences the evolution dynamics that is opposed by the large
Faraday current due to electric field generated by the time varying $\vec{B}$.
We show that the resultant effects entail a significantly large directed flow
($v_1$) of charm quarks (CQs) compared to light quarks due to a combination of
several favorable conditions for CQs, mainly: (i) unlike light quarks formation
time scale of CQs, $\tau_f \simeq \, 0.1 \rm fm/c$ is comparable to the time
scale when $\vec B$ attains its maximum value and (ii) the kinetic relaxation
time of CQs is similar to the QGP lifetime, this helps the CQ to retain the
initial kick picked up from the electromagnetic field in the transverse
direction. The effect is also odd under charge exchange allowing to distinguish
it from the vorticity of the bulk matter due to the initial angular momentum
conservation; conjointly thanks to its mass, $M_c >>\Lambda_{QCD}$, there
should be no mixing with the chiral magnetic dynamics. Hence CQs provide very
crucial and independent information on the strength of the magnetic field
produced in HIC.


title:
Trapping Centers at the Superfluid-Mott-insulator Criticality:
  Transition between Charge-quantized States

abstract:
  Under the conditions of superfluid-Mott-insulator criticality in two
dimensions, the trapping centers--i.e., local potential wells and bumps--are
generically characterized by an integer charge corresponding to the number of
trapped particles (if positive) or holes (if negative). Varying the strength of
the center leads to a transition between two competing ground states with
charges differing by $\pm 1$. The hallmark of the transition scenario is a
splitting of the number density distortion, $\delta n(r)$, into a half-integer
core and a large halo carrying the complementary charge of $\pm 1/2$. The sign
of the halo changes across the transition and the radius of the halo, $r_0$,
diverges on the approach to the critical strength of the center, $V = V_c$, by
the law $r_0 \propto |V-V_c|^{-\tilde{\nu}}$, with $\tilde{\nu} \approx
2.33(5)$.


title: Kinetic analysis of negative power deposition in low pressure plasmas

abstract:
  The negative power absorption in low pressure plasmas is investigated by
means of an analyical model which couples Boltzmann's equation and the
quasi-stationary Maxwell's equation. Exploiting standard Hilbert space methods
an explicit solution for both, the electric field and the distribution function
of the electrons for a bounded discharge configuration subject to an
unsymmetrical excitation has been found for the first time. The model is
applied to a low pressure inductively coupled plasma discharge. In this context
particularly the anomalous skin effect and the effect of phase mixing is
discussed. The analytical solution is compared with results from
electromagnetic full wave particle in cell simulations. Excellent agreement
between the analytical and the numerical results is found.


title: CMB-S4 and the Hemispherical Variance Anomaly

abstract:
  Cosmic Microwave Background (CMB) full-sky temperature data show a
hemispherical asymmetry in power nearly aligned with the Ecliptic. In real
space, this anomaly can be quantified by the temperature variance in the
northern and southern Ecliptic hemispheres. In this context, the northern
hemisphere displays an anomalously low variance while the southern hemisphere
appears unremarkable (consistent with expectations from the best-fitting
theory, $\Lambda$CDM). While this is a well established result in temperature,
the low signal-to-noise ratio in current polarization data prevents a similar
comparison. This will change with a proposed ground-based CMB experiment,
CMB-S4. With that in mind, we generate realizations of polarization maps
constrained by the temperature data and predict the distribution of the
hemispherical variance in polarization considering two different sky coverage
scenarios possible in CMB-S4: full Ecliptic north coverage and just the portion
of the North that can be observed from a ground based telescope at the high
Chilean Atacama plateau. We find that even in the set of realizations
constrained by the temperature data, the low northern hemisphere variance
observed in temperature is not expected in polarization. Therefore, an
anomalously low variance detection in polarization would provide strong
evidence against the hypothesis that the temperature anomaly is simply a
statistical fluke. We show, within $\Lambda$CDM, how variance measurements in
both sky coverage scenarios are related. We find that the variance makes for a
good statistic in cases where the sky coverage is limited, however a full
northern coverage is still preferable.


title: On converting community detection algorithms for fuzzy graphs in Neo4j

abstract:
  An essential feature of large scale free graphs, such as the Web,
protein-to-protein interaction, brain connectivity, and social media graphs, is
that they tend to form recursive communities. The latter are densely connected
vertex clusters exhibiting quick local information dissemination and
processing. Under the fuzzy graph model vertices are fixed while each edge
exists with a given probability according to a membership function. This paper
presents Fuzzy Walktrap and Fuzzy Newman-Girvan, fuzzy versions of two
established community discovery algorithms. The proposed algorithms have been
applied to a synthetic graph generated by the Kronecker model with different
termination criteria and the results are discussed.


title: Bootstrapping Face Detection with Hard Negative Examples

abstract:
  Recently significant performance improvement in face detection was made
possible by deeply trained convolutional networks. In this report, a novel
approach for training state-of-the-art face detector is described. The key is
to exploit the idea of hard negative mining and iteratively update the Faster
R-CNN based face detector with the hard negatives harvested from a large set of
background examples. We demonstrate that our face detector outperforms
state-of-the-art detectors on the FDDB dataset, which is the de facto standard
for evaluating face detection algorithms.


title:
Magnetic fingerprint of interfacial coupling between CoFe and nanoscale
  ferroelectric domain walls

abstract:
  Magnetoelectric coupling in ferromagnet/multiferroic systems is often
manifested in the exchange bias effect, which may have combined contributions
from multiple sources, such as domain walls, chemical defects or strain. In
this study we magnetically "fingerprint" the coupling behavior of CoFe grown on
epitaxial BiFeO3 (BFO) thin films by magnetometry and
first-order-reversal-curves (FORC). The contribution to exchange bias from
71{\deg}, 109{\deg} and charged ferroelectric domain walls (DWs) was elucidated
by the FORC distribution. CoFe samples grown on BFO with 71{\deg} DWs only
exhibit an enhancement of the coercivity, but little exchange bias. Samples
grown on BFO with 109{\deg} DWs and mosaic DWs exhibit a much larger exchange
bias, with the main enhancement attributed to 109{\deg} and charged DWs. Based
on the Malozemoff random field model, a varying-anisotropy model is proposed to
account for the exchange bias enhancement. This work sheds light on the
relationship between the exchange bias effect of the CoFe/BFO heterointerface
and the ferroelectric DWs, and provides a path for multiferroic device analysis
and design.


title: Resonances for open quantum maps and a fractal uncertainty principle

abstract:
  We study eigenvalues of quantum open baker's maps with trapped sets given by
linear arithmetic Cantor sets of dimensions $\delta\in (0,1)$. We show that the
size of the spectral gap is strictly greater than the standard bound
$\max(0,{1\over 2}-\delta)$ for all values of $\delta$, which is the first
result of this kind. The size of the improvement is determined from a fractal
uncertainty principle and can be computed for any given Cantor set. We next
show a fractal Weyl upper bound for the number of eigenvalues in annuli, with
exponent which depends on the inner radius of the annulus.


title:
Deep Learning a Grasp Function for Grasping under Gripper Pose
  Uncertainty

abstract:
  This paper presents a new method for parallel-jaw grasping of isolated
objects from depth images, under large gripper pose uncertainty. Whilst most
approaches aim to predict the single best grasp pose from an image, our method
first predicts a score for every possible grasp pose, which we denote the grasp
function. With this, it is possible to achieve grasping robust to the gripper's
pose uncertainty, by smoothing the grasp function with the pose uncertainty
function. Therefore, if the single best pose is adjacent to a region of poor
grasp quality, that pose will no longer be chosen, and instead a pose will be
chosen which is surrounded by a region of high grasp quality. To learn this
function, we train a Convolutional Neural Network which takes as input a single
depth image of an object, and outputs a score for each grasp pose across the
image. Training data for this is generated by use of physics simulation and
depth image simulation with 3D object meshes, to enable acquisition of
sufficient data without requiring exhaustive real-world experiments. We
evaluate with both synthetic and real experiments, and show that the learned
grasp score is more robust to gripper pose uncertainty than when this
uncertainty is not accounted for.


title: The forward-backward algorithm and the normal problem

abstract:
  The forward-backward splitting technique is a popular method for solving
monotone inclusions that has applications in optimization. In this paper we
explore the behaviour of the algorithm when the inclusion problem has no
solution. We present a new formula to define the normal solutions using the
forward-backward operator. We also provide a formula for the range of the
displacement map of the forward-backward operator. Several examples illustrate
our theory.


title: Sequential estimation in the group testing problem

abstract:
  Estimation using pooled sampling has long been an area of interest in the
group testing literature. Such research has focused primarily on the assumed
use of fixed sampling plans (i), although some recent papers have suggested
alternative sequential designs that sample until a predetermined number of
positive tests (ii). One major consideration, including in the new work on
sequential plans, is the construction of debiased estimators which either
reduce or keep the mean square error from inflating. Whether, however, under
the above or other sampling designs unbiased estimation is in fact possible has
yet to be established in the literature. In this paper, we introduce a design
which samples until a fixed number of negatives (iii), and show that an
unbiased estimator exists under this model, while unbiased estimation is not
possible for either of the preceding designs (i) and (ii). We present new
estimators under the different sampling plans that are either unbiased or that
have reduced bias relative to those already in use as well as generally improve
on the mean square error. Numerical studies are done in order to compare
designs in terms of bias and mean square error under practical situations with
small and medium sample sizes.


title: Sofic boundaries of groups and coarse geometry of sofic approximations

abstract:
  Sofic groups generalise both residually finite and amenable groups, and the
concept is central to many important results and conjectures in measured group
theory. We introduce a topological notion of a sofic boundary attached to a
given sofic approximation of a finitely generated group and use it to prove
that coarse properties of the approximation (property A, asymptotic coarse
embeddability into Hilbert space, geometric property (T)) imply corresponding
analytic properties of the group (amenability, a-T-menability and property
(T)), thus generalising ideas and results present in the literature for
residually finite groups and their box spaces. Moreover, we generalise coarse
rigidity results for box spaces due to Kajal Das, proving that coarsely
equivalent sofic approximations of two groups give rise to a uniform measure
equivalence between those groups. Along the way, we bring to light a coarse
geometric view point on ultralimits of a sequence of finite graphs first
exposed by Jan \v{S}pakula and Rufus Willett, as well as proving some bridging
results concerning measure structures on topological groupoid Morita
equivalences that will be of interest to groupoid specialists.


title: On strong bounds of rate of convergence for regenerative processes

abstract:
  We give strong bounds for the rate of convergence of the regenerative process
distribution to the stationary distribution in the total variation metric.
These bounds are obtained by using coupling method. We propose this method for
obtaining such bounds for the queueing regenerative processes.


title: Gravitational waves from a plunge into a nearly extremal Kerr black hole

abstract:
  We study numerically in the time domain the linearized gravitational waves
emitted from a plunge into a nearly extremal Kerr black hole by solving the
inhomogeneous Teukolsky equation. We consider spinning black holes for which
the specific spin angular momentum $a/M=1-\epsilon$, and we consider values of
$\epsilon\geq 10^{-6}$. We find an effective transient behavior for the
quasi-normal ringdown: the early phase of the quasi-normal ringdown is governed
by a decay according to inverse time, with frequency equaling twice the black
hole's horizon frequency. The smaller $\epsilon$ the later the transition from
this transient inverse time decay to exponential decay. Such sources, if exist,
may be interesting potential sources for terrestrial or space borne
gravitational wave observatories.


title:
Solutions of the bi-confluent Heun equation in terms of the Hermite
  functions

abstract:
  We construct an expansion of the solutions of the bi-confluent Heun equation
in terms of the Hermite functions. The series is governed by a three-term
recurrence relation between successive coefficients of the expansion. We
examine the restrictions that are imposed on the involved parameters in order
that the series terminates thus resulting in closed-form finite-sum solutions
of the bi-confluent Heun equation. A physical application of the closed-form
solutions is discussed. We present the five six-parametric potentials for which
the general solution of the one-dimensional Schr\"odinger equation is written
in terms of the bi-confluent Heun functions and further identify a particular
conditionally integrable potential for which the involved bi-confluent Heun
function admits a four-term finite-sum expansion in terms of the Hermite
functions. This is an infinite well defined on a half-axis. We present the
explicit solution of the one-dimensional Schr\"odinger equation for this
potential and discuss the bound states supported by the potential. We derive
the exact equation for the energy spectrum and construct an accurate
approximation for the bound-state energy levels.


title: Cram\'er type moderate deviations for intermediate trimmed means

abstract:
  In this article we establish Cram\'er type moderate deviation results for
(intermediate) trimmed means $T_n=n^{-1} \sum_{i=k_n+1}^{n-m_n}X_{i:n}$, where
$X_{i:n}$ -- the order statistics corresponding to the first $n$ observations
of a~sequence $X_1,X_2,\dots $ of i.i.d random variables with $df$ $F$. We
consider two cases of intermediate and heavy trimming. In the former case, when
$\max(\alpha_n,\beta_n)\to 0$ ($\alpha_n=k_n/n$, $\beta_n=m_n/n$) and
$\min(k_n,m_n)\to\infty$ as $n\to\infty$, we obtain our results under a~natural
moment condition and a~mild condition on the rate at which $\alpha_n$ and
$\beta_n$ tend to zero. In the latter case we do not impose any moment
conditions on $F$, instead, we require some smoothness of $F^{-1}$ in an~open
set containing the limit points of the trimming sequences $\alpha_n$,
$1-\beta_n$.


title: Information Security as Strategic (In)effectivity

abstract:
  Security of information flow is commonly understood as preventing any
information leakage, regardless of how grave or harmless consequences the
leakage can have. In this work, we suggest that information security is not a
goal in itself, but rather a means of preventing potential attackers from
compromising the correct behavior of the system. To formalize this, we first
show how two information flows can be compared by looking at the adversary's
ability to harm the system. Then, we propose that the information flow in a
system is effectively information-secure if it does not allow for more harm
than its idealized variant based on the classical notion of noninterference.


title: Analysis of Scanned Probe Images for Magnetic Focusing in Graphene

abstract:
  We use a cooled Scanning Probe Microscope (SPM) to electron motion in
nanoscale devices. The charged tip of the SPM is raster scanned at a constant
height above the surface as the conductance of the device is measured. The
image charge scatters electrons away, changing the path of electrons through
the sample.1-3 Using this technique, we have imaged cyclotron orbits3 for
ballistic hBN-graphene-hBN devices that flow between two narrow contacts in the
magnetic focusing regime. Here we present an analysis of our magnetic focusing
imaging results based on the effects of the tip-created charge density dip on
the motion of ballistic electrons. The density dip locally reduces the Fermi
energy, creating a force that pushes electrons away from the tip. When the tip
is above the cyclotron orbit, electrons are deflected away from the receiving
contact, creating an image by reducing the transmission between contacts. The
data and our analysis suggest that graphene edge is rather rough, and electrons
scattering off the edge bounce in random directions. However, when the tip is
close to the edge it can enhance transmission by bouncing electrons away from
the edge, toward the receiving contact. Our results demonstrate that a cooled
SPM is a promising tool to investigate the motion of electrons in ballistic
graphene devices.


title: The short pulse equation by a Riemann-Hilbert approach

abstract:
  We develop a Riemann-Hilbert approach to the inverse scattering transform
method for the short pulse (SP) equation $u_{xt}=u+\frac{1}{6}(u^3)_{xx}$ with
zero boundary conditions (as $|x|\to\infty$). This approach is directly applied
to the Lax pair for the SP equation. It allows us to give a parametric
representation of the solution to the Cauchy problem. This representation is
then used for studying the long-time behavior of the solution as well as for
retrieving the soliton solutions. Finally, the analysis of the long-time
behavior allows us to formulate, in spectral terms, a sufficient condition for
the wave breaking.


title: Imaging Electron Motion in a Few Layer MoS2 Device

abstract:
  Ultrathin sheets of MoS2 are a newly discovered 2D semiconductor that holds
great promise for nanoelectronics. Understanding the pattern of current flow
will be crucial for developing devices. In this talk, we present images of
current flow in MoS2 obtained with a Scanned Probe Microscope (SPM) cooled to 4
K. We previously used this technique to image electron trajectories in
GaAs/AlGaAs heterostructures and graphene. The charged SPM tip is held just
above the sample surface, creating an image charge inside the device that
scatters electrons. By measuring the change in resistance {\Delta}R while the
tip is raster scanned above the sample, an image of electron flow is obtained.
We present images of electron flow in an MoS2 device patterned into a hall bar
geometry. A three-layer MoS2 sheet is encased by two hBN layers, top and
bottom, and patterned into a hall-bar with multilayer graphene contacts. An SPM
image shows the current flow pattern from the wide contact at the end of the
device for a Hall density n = 1.3x10^12 cm^-2. The SPM tip tends to block flow,
increasing the resistance R. The pattern of flow was also imaged for a narrow
side contact on the sample. At density n = 5.4x10^11 cm^-2; the pattern seen in
the SPM image is similar to the wide contact. The ability to image electron
flow promises to be very useful for the development of ultrathin devices from
new 2D materials.


title:
Uniform confidence bands in deconvolution with unknown error
  distribution

abstract:
  This paper develops a method to construct uniform confidence bands in
deconvolution when the error distribution is unknown. We mainly focus on the
baseline setting where an auxiliary sample from the error distribution is
available and the error density is ordinary smooth. The auxiliary sample may
directly come from validation data, or can be constructed from panel data with
a symmetric error distribution. We also present extensions of the results on
confidence bands to the case of super-smooth error densities. Simulation
studies demonstrate the performance of the multiplier bootstrap confidence band
in the finite sample. We apply our method to the Outer Continental Shelf (OCS)
Auction Data and draw confidence bands for the density of common values of
mineral rights on oil and gas tracts. Finally, we present an application of our
main theoretical result specifically to additive fixed-effect panel data
models. As an empirical illustration of the panel data analysis, we draw
confidence bands for the density of the total factor productivity in a
manufacturing industry in Chile.


title: Scl-1013644: a CEMP-s star in the Sculptor Dwarf Spheroidal Galaxy

abstract:
  Recent studies of the Milky Way and its satellites have paid special
attention to the importance of carbon-enhanced metal-poor (CEMP) stars due to
their involvement in Galactic formation history and their possible connection
with the chemical elements originating in the first stellar generation. In an
ongoing study of red giants in the Sculptor dwarf galaxy we have discovered a
star with extremely strong CN and CH molecular bands. This star, Scl-1013644,
has previously been identified by Geisler et al. (2005) as a star with an
enrichment in the heavy elements. Spectrum synthesis has been used to derive
the carbon, nitrogen and barium abundances for Scl-1013644. Our findings are
[C/Fe] = +0.8, [N/Fe] = -0.3 and [Ba/Fe] = +2.1 with the latter result
consistent with the value found by Geisler et al. (2005). These results reveal
Scl-1013644 as a CEMP-s star, the third such star discovered in this dwarf
galaxy.


title:
Helical Nanomachines for Fast Mechanical Mapping of Heterogeneous
  Environments

abstract:
  Artificial micro and nano machines have been envisioned and demonstrated as
potential candidates for variety of applications, ranging from targeted drug or
gene delivery, cell manipulation, environmental sensing and many more. Here, we
demonstrate the application of helical nanomachines that can measure and map
the local rheological properties of a complex heterogeneous environment. The
position of the helical nanomachine was controlled precisely using magnetic
fields, while the instantaneous orientation provided an estimation of the
viscosity of the surrounding medium with high spatial and temporal accuracy.
Apart from providing viscosity estimates in purely viscous and viscoelastic
media with shear rate independent viscosity (Boger fluids), their motion was
also found to be extremely sensitive to fluid elasticity. Taken together we
report a promising new technique of mapping the rheological properties of a
complex fluidic environment by helical nanomachines with high spatial and
temporal resolutions, a functionality that goes beyond the capabilities of
existing passive and active microrheological methods.


title:
Reconciling Lambek's restriction, cut-elimination, and substitution in
  the presence of exponential modalities

abstract:
  The Lambek calculus can be considered as a version of non-commutative
intuitionistic linear logic. One of the interesting features of the Lambek
calculus is the so-called "Lambek's restriction," that is, the antecedent of
any provable sequent should be non-empty. In this paper we discuss ways of
extending the Lambek calculus with the linear logic exponential modality while
keeping Lambek's restriction. Interestingly enough, we show that for any system
equipped with a reasonable exponential modality the following holds: if the
system enjoys cut elimination and substitution to the full extent, then the
system necessarily violates Lambek's restriction. Nevertheless, we show that
two of the three conditions can be implemented. Namely, we design a system with
Lambek's restriction and cut elimination and another system with Lambek's
restriction and substitution. For both calculi we prove that they are
undecidable, even if we take only one of the two divisions provided by the
Lambek calculus. The system with cut elimination and substitution and without
Lambek's restriction is folklore and known to be undecidable.


title:
Spontaneous Facial Micro-Expression Recognition using Discriminative
  Spatiotemporal Local Binary Pattern with an Improved Integral Projection

abstract:
  Recently, there are increasing interests in inferring mirco-expression from
facial image sequences. Due to subtle facial movement of micro-expressions,
feature extraction has become an important and critical issue for spontaneous
facial micro-expression recognition. Recent works usually used spatiotemporal
local binary pattern for micro-expression analysis. However, the commonly used
spatiotemporal local binary pattern considers dynamic texture information to
represent face images while misses the shape attribute of face images. On the
other hand, their works extracted the spatiotemporal features from the global
face regions, which ignore the discriminative information between two
micro-expression classes. The above-mentioned problems seriously limit the
application of spatiotemporal local binary pattern on micro-expression
recognition. In this paper, we propose a discriminative spatiotemporal local
binary pattern based on an improved integral projection to resolve the problems
of spatiotemporal local binary pattern for micro-expression recognition.
Firstly, we develop an improved integral projection for preserving the shape
attribute of micro-expressions. Furthermore, an improved integral projection is
incorporated with local binary pattern operators across spatial and temporal
domains. Specifically, we extract the novel spatiotemporal features
incorporating shape attributes into spatiotemporal texture features. For
increasing the discrimination of micro-expressions, we propose a new feature
selection based on Laplacian method to extract the discriminative information
for facial micro-expression recognition. Intensive experiments are conducted on
three availably published micro-expression databases. We compare our method
with the state-of-the-art algorithms. Experimental results demonstrate that our
proposed method achieves promising performance for micro-expression
recognition.


title: A Distance-Based Approach to Strong Target Control of Dynamical Networks

abstract:
  This paper deals with controllability of dynamical networks. It is often
unfeasible or unnecessary to fully control large-scale networks, which
motivates the control of a prescribed subset of agents of the network. This
specific form of output control is known under the name target control. We
consider target control of a family of linear control systems associated with a
network, and provide both a necessary and a sufficient topological condition
under which the network is strongly targeted controllable. Furthermore, a
leader selection algorithm is presented to compute leader sets achieving target
control.


title: Robust High-Dimensional Linear Regression

abstract:
  The effectiveness of supervised learning techniques has made them ubiquitous
in research and practice. In high-dimensional settings, supervised learning
commonly relies on dimensionality reduction to improve performance and identify
the most important factors in predicting outcomes. However, the economic
importance of learning has made it a natural target for adversarial
manipulation of training data, which we term poisoning attacks. Prior
approaches to dealing with robust supervised learning rely on strong
assumptions about the nature of the feature matrix, such as feature
independence and sub-Gaussian noise with low variance. We propose an integrated
method for robust regression that relaxes these assumptions, assuming only that
the feature matrix can be well approximated by a low-rank matrix. Our
techniques integrate improved robust low-rank matrix approximation and robust
principle component regression, and yield strong performance guarantees.
Moreover, we experimentally show that our methods significantly outperform
state of the art both in running time and prediction error.


title: Toral stabilizers of restricted Lie algebras

abstract:
  This paper investigates the toral stabilizer of a finite-dimensional
restricted Lie algebra $(\mathfrak{g},[p])$, defined over an algebraically
closed field $k$ of positive characteristic. We compute the group of toral
stabilizers of some simple Lie algebras and give a new characterization of the
solvable restricted Lie algebras. Moreover, we determine the subalgebra
structure of exceptional simple Lie algebras in good characteristic. We also
provide applications, which concern the distribution of weight spaces.


title:
Temperature and interaction dependence of the moment of inertia of a
  rotating condensate boson gas

abstract:
  In this paper, a developed Hartree-Fock semiclassical approximation is used
to calculate the temperature and interaction dependence of the moment of
inertia of a rotating condensate Boson gas. A fully classical and quantum
mechanical treatment for the moment of inertia are given in terms of the
normalized temperature. We found that the moment of inertia is considerably
affected by the interaction. The present analysis, shows that the superfluid
effects in the moment of inertia of a condensate Boson gas can be observed at
temperatures $T > .25 T_0 $ and not dramatically smaller than $T_0$.


title: Theory of stochastic Laplacian growth

abstract:
  We generalize the diffusion-limited aggregation by issuing many
randomly-walking particles, which stick to a cluster at the discrete time unit
providing its growth. Using simple combinatorial arguments we determine
probabilities of different growth scenarios and prove that the most probable
evolution is governed by the deterministic Laplacian growth equation. A
potential-theoretical analysis of the growth probabilities reveals connections
with the tau-function of the integrable dispersionless limit of the
two-dimensional Toda hierarchy, normal matrix ensembles, and the
two-dimensional Dyson gas confined in a non-uniform magnetic field. We
introduce the time-dependent Hamiltonian, which generates transitions between
different classes of equivalence of closed curves, and prove the Hamiltonian
structure of the interface dynamics. Finally, we propose a relation between
probabilities of growth scenarios and the semi-classical limit of certain
correlation functions of "light" exponential operators in the Liouville
conformal field theory on a pseudosphere.

categories: cond-mat.stat-mech hep-th math-ph math.MP nlin.SI


title: Conjecture of perturbative QED breakdown at $\alpha\chi^{2/3} \gtrsim 1$

abstract:
  Invited talk given at Symposium "Extreme Light Technologies, Science, and
Applications" (LPHYS'16, Yerevan, 11-15 July 2016). The old Ritus-Narozhny
conjecture of possible breakdown of Intense Field QED perturbation theory for
ultrarelativistic particles passing transversely through a strong
electromagnetic field is reviewed with a special emphasis on its possible
significance for near-future experiments.


title:
Explicit expressions for the moments of the size of an (s,s+1)-core
  partition with distinct parts

abstract:
  For fixed s, the size of an (s, s+1)-core partition with distinct parts can
be seen as a random variable X_s. Using computer-assisted methods, we derive
formulas for the expectation, variance, and higher moments of X_s. Our results
give good evidence that X_s is asymptotically normal.


title: Experimental quantum compressed sensing for a seven-qubit system

abstract:
  Well-controlled quantum devices with their increasing system size face a new
roadblock hindering further development of quantum technologies: The effort of
quantum tomography---the characterization of processes and states within a
quantum device---scales unfavorably to the point that state-of-the-art systems
can no longer be treated. Quantum compressed sensing mitigates this problem by
reconstructing the state from an incomplete set of observables. In this work,
we present an experimental implementation of compressed tomography of a seven
qubit system---the largest-scale realization to date---and we introduce new
numerical methods in order to scale the reconstruction to this dimension.
Originally, compressed sensing has been advocated for density matrices with few
non-zero eigenvalues. Here, we argue that the low-rank estimates provided by
compressed sensing can be appropriate even in the general case. The reason is
that statistical noise often allows only for the leading eigenvectors to be
reliably reconstructed: We find that the remaining eigenvectors behave in a way
consistent with a random matrix model that carries no information about the
true state. We report a reconstruction of quantum states from a topological
color code of seven qubits, prepared in a trapped ion architecture, based on
tomographically incomplete data involving 127 Pauli basis measurement settings
only, repeated 100 times each.


title:
Beaming structures of Jupiter's decametric common S-bursts observed from
  LWA1, NDA, and URAN2 radio telescopes

abstract:
  On 2015 February 21, simultaneous observations of Jupiter's decametric radio
emission between 10 and 33 MHz were carried out using three powerful
low-frequency radio telescopes: Long Wavelength Array Station One (LWA1) in
USA; Nan\c{c}ay Decameter Array (NDA) in France; and URAN2 telescope in
Ukraine. We measure lag times of short-bursts (S-bursts) for 105-minutes of
data over effective baselines up to 8460 km by using cross-correlation analysis
of the spectrograms from each instrument. Of particular interest is the
measurement of the beaming thickness of S-bursts, testing if either flashlight-
or beacon-like beaming is emanating from Jupiter. We find that the lag times
for all pairs drift slightly as time elapses, in agreement with expectations
from the flashlight-like beaming model. This leads to a new constraint of the
minimum beaming thickness of 2.66". Also, we find that most of the analyzed
data abound with S-bursts, whose occurrence probability peaks at 17-18 MHz.


title:
A rich structure related to the construction of analytic matrix
  functions

abstract:
  We analyse two special cases of $\mu$-synthesis problems which can be reduced
to interpolation problems in the set of analytic functions from the disc into
the symmetrised bidisc and into the tetrablock. For these inhomogeneous domains
we study the structure of interconnections between the set of analytic
functions from the disc into the given domain, the matricial Schur class, the
Schur class of the bidisc, and the set of pairs of positive kernels on the
bidisc subject to a boundedness condition. We use the theories of Hilbert
function spaces and of reproducing kernels to establish these connections. We
give a solvability criterion for the interpolation problem that arises from the
$\mu$-synthesis problem related to the tetrablock.


title: Reference Governor Strategies for Vehicle Rollover Avoidance

abstract:
  The paper addresses the problem of vehicle rollover avoidance using reference
governors applied to modify the driver steering input in vehicles with an
active steering system. Several reference governor designs are presented and
tested with a detailed nonlinear simulation model. The vehicle dynamics are
highly nonlinear for large steering angles, including the conditions where the
vehicle approaches a rollover onset, which necessitates reference governor
design changes. Simulation results show that reference governor designs are
effective in avoiding rollover. The results also demonstrate that the
controllers are not overly conservative, adjusting the driver steering input
only for very high steering angles.


title:
Crank-Nicolson Galerkin approximations to nonlinear Schr\"odinger
  equations with rough potentials

abstract:
  This paper analyses the numerical solution of a class of non-linear
Schr\"odinger equations by Galerkin finite elements in space and a mass- and
energy conserving variant of the Crank-Nicolson method due to Sanz-Serna in
time. The novel aspects of the analysis are the incorporation of rough,
discontinuous potentials in the context of weak and strong disorder, the
consideration of some general class of non-linearities, and the proof of
convergence with rates in $L^{\infty}(L^2)$ under moderate regularity
assumptions that are compatible with discontinuous potentials. For sufficiently
smooth potentials, the rates are optimal without any coupling condition between
the time step size and the spatial mesh width.


title: Dispersion Operators Algebra and Linear Canonical Transformations

abstract:
  This work intends to present a study on relations between a Lie algebra
called dispersion operators algebra, linear canonical transformation and a
phase space representation of quantum mechanics that we have introduced and
studied in previous works. The paper begins with a brief recall of our previous
works followed by the description of the dispersion operators algebra which is
performed in the framework of the phase space representation. Then, linear
canonical transformations are introduced and linked with this algebra. A
multidimensional generalization of the obtained results is given


title:
Combinatorial properties of symmetric polynomials from integrable vertex
  models in finite lattice

abstract:
  We introduce and study several combinatorial properties of a class of
symmetric polynomials from the point of view of integrable vertex models in
finite lattice. We introduce the $L$-operator related with the $U_q(sl_2)$
$R$-matrix, and construct the wavefunctions and their duals. We prove the exact
correspondence between the wavefunctions and symmetric polynomials which is a
quantum group deformation of the Grothendieck polynomials. This is proved by
combining the matrix product method and an analysis on the domain wall boundary
partition functions. As applications of the correspondence between the
wavefunctions and symmetric polynomials, we derive several properties of the
symmetric polynomials such as the determinant pairing formulas and the
branching formulas by analyzing the domain wall boundary partition functions
and the matrix elements of the $B$-operators.


title:
Two-loop RGE of a general renormalizable Yang-Mills theory in a
  renormalization scheme with an explicit UV cutoff

abstract:
  We perform a systematic one-loop renormalization of a general renormalizable
Yang-Mills theory coupled to scalars and fermions using a regularization scheme
with a smooth momentum cutoff $\Lambda$ (implemented through an exponential
damping factor). We construct the necessary finite counterterms restoring the
BRST invariance of the effective action by analyzing the relevant
Slavnov-Taylor identities. We find the relation between the renormalized
parameters in our scheme and in the conventional $\overline{\rm MS}$ scheme
which allow us to obtain the explicit two-loop renormalization group equations
in our scheme from the known two-loop ones in the $\overline{\rm MS}$ scheme.
We calculate in our scheme the divergences of two-loop vacuum graphs in the
presence of a constant scalar background field which allow us to rederive the
two-loop beta functions for parameters of the scalar potential. We also prove
that consistent application of the proposed regularization leads to
counterterms which, together with the original action, combine to a bare action
expressed in terms of bare parameters. This, together with treating $\Lambda$
as an intrinsic scale of a hypothetical underlying finite theory of all
interactions, offers a possibility of an unconventional solution to the
hierarchy problem if no intermediate scales between the electroweak scale and
the Planck scale exist.


title: The effect of rotation on the heat transfer between two nanoparticles

abstract:
  Quantizing the electromagnetic vacuum and medium fields of two nanoparticles,
we investigate the heat transfer between them. One of the particles has been
considered to rotate by angular velocity $ \omega_0 $. The effect of rotation
on the absorbed heat power by the rotating nanoparticle is discussed. The
results for angular velocities much smaller than the relaxation frequency $
\Gamma $ of the dielectrics are in agreement with the static nanoparticles,
however increasing the angular velocity $ \omega_0 $ in comparison to the
relaxation frequency of the dielectrics $ (\omega_0\geqslant \Gamma) $
generates two sidebands in the spectrum of the absorbed heat power. The
well-known near-field and far-field effects are studied and it is shown that
the sidebands peaks in far-field are considerable in comparison to the main
peak frequency of the spectrum.


title:
Incorporation of Speech Duration Information in Score Fusion of Speaker
  Recognition Systems

abstract:
  In recent years identity-vector (i-vector) based speaker verification (SV)
systems have become very successful. Nevertheless, environmental noise and
speech duration variability still have a significant effect on degrading the
performance of these systems. In many real-life applications, duration of
recordings are very short; as a result, extracted i-vectors cannot reliably
represent the attributes of the speaker. Here, we investigate the effect of
speech duration on the performance of three state-of-the-art speaker
recognition systems. In addition, using a variety of available score fusion
methods, we investigate the effect of score fusion for those speaker
verification techniques to benefit from the performance difference of different
methods under different enrollment and test speech duration conditions. This
technique performed significantly better than the baseline score fusion
methods.


title: Estimating scaled treatment effects with multiple outcomes

abstract:
  In classical study designs, the aim is often to learn about the effects of a
treatment or intervention on a single outcome; in many modern studies, however,
data on multiple outcomes are collected and it is of interest to explore
effects on multiple outcomes simultaneously. Such designs can be particularly
useful in patient-centered research, where different outcomes might be more or
less important to different patients. In this paper we propose scaled effect
measures (via potential outcome notation) that translate effects on multiple
outcomes to a common scale, using mean-variance and median-interquartile-range
-based standardizations. We present efficient, nonparametric, doubly robust
methods for estimating these scaled effects (and weighted average summary
measures), and for testing the null hypothesis that treatment affects all
outcomes equally. We also discuss methods for exploring how treatment effects
depend on covariates (i.e., effect modification). In addition to describing
efficiency theory for our estimands and the asymptotic behavior of our
estimators, we illustrate the methods in a simulation study and a data
analysis. Importantly, and in contrast to much of the literature concerning
effects on multiple outcomes, our methods are nonparametric and can be used not
only in randomized trials to yield increased efficiency, but also in
observational studies with high-dimensional covariates to reduce confounding
bias.


title: Distributed Real-Time Energy Management in Data Center Microgrids

abstract:
  Data center operators are typically faced with three significant problems
when running their data centers, i.e., rising electricity bills, growing carbon
footprints and unexpected power outages. To mitigate these issues, running data
centers in microgrids is a good choice since microgrids can enhance the energy
efficiency, sustainability and reliability of electrical services. Thus, in
this paper, we investigate the problem of energy management for multiple data
center microgrids. Specifically, we intend to minimize the long-term
operational cost of data center microgrids by taking into account the
uncertainties in electricity prices, renewable outputs and data center
workloads. We first formulate a stochastic programming problem with the
considerations of many factors, e.g., providing heterogeneous service delay
guarantees for batch workloads, interactive workload allocation, batch workload
shedding, electricity buying/selling, battery charging/discharging efficiency,
and the ramping constraints of backup generators. Then, we design a realtime
and distributed algorithm for the formulated problem based on Lyapunov
optimization technique and a variant of alternating direction method of
multipliers (ADMM). Moreover, the performance guarantees provided by the
proposed algorithm are analyzed. Extensive simulation results indicate the
effectiveness of the proposed algorithm in operational cost reduction for data
center microgrids.


title:
Geometry of moduli spaces of rational curves in linear sections of
  Grassmannian $Gr(2,5)$

abstract:
  We prove that the moduli spaces of rational curves of degree at most $3$ in
linear sections of the Grassmannian $Gr(2,5)$ are all rational varieties. We
also study their compactifications and birational geometry.


title: Decentralized Biconnectivity Conditions in Multi-robot Systems

abstract:
  The network connectivity in a group of cooperative robots can be easily
broken if one of them loses its connectivity with the rest of the group. In
case of having robustness with respect to one-robot-fail, the communication
network is termed biconnected. In simple words, to have a biconnected network
graph, we need to prove that there exists no articulation point. We propose a
decentralized approach that provides sufficient conditions for biconnectivity
of the network, and we prove that these conditions are related to the third
smallest eigenvalue of the Laplacian matrix. Data exchange among the robots is
supposed to be neighbor-to-neighbor.


title:
Neon and [CII] 158 micron Emission Line Profiles in Dusty Starbursts and
  Active Galactic Nuclei

abstract:
  The sample of 379 extragalactic sources is presented that have mid-infrared,
high resolution spectroscopy with the Spitzer Infrared Spectrograph (IRS) and
also spectroscopy of the [CII] 158 um line with the Herschel Photodetector
Array Camera and Spectrometer (PACS). The emission line profiles of [NeII]
12.81 um, [NeIII] 15.55 um, and [CII] 158 um are presented, and intrinsic line
widths are determined (full width half maximum of Gaussian profiles after
instrumental correction). All line profiles together with overlays comparing
positions of PACS and IRS observations are made available in the Cornell Atlas
of Spitzer IRS Sources (CASSIS). Sources are classified from AGN to starburst
based on equivalent widths of the 6.2 um polycyclic aromatic hydrocarbon
feature. It is found that intrinsic line widths do not change among
classification for [CII], with median widths of 207 km per s for AGN, 248 km
per s for composites, and 233 km per s for starbursts. The [NeII] line widths
also do not change with classification, but [NeIII] lines are progressively
broader from starburst to AGN. A small number of objects with unusually broad
lines or unusual redshift differences in any feature are identified.


title: Understanding solar torsional oscillations from global dynamo models

abstract:
  The phenomenon of solar "torsional oscillations" (TO) represents migratory
zonal flows associated with the solar cycle. These flows are observed on the
solar surface and, according to helioseismology, extend through the convection
zone. We study the origin of the TO using results from a global MHD simulation
of the solar interior that reproduces several of the observed characteristics
of the mean-flows and magnetic fields. Our results indicate that the magnetic
tension (MT) in the tachocline region is a key factor for the periodic changes
in the angular momentum transport that causes the TO. The torque induced by the
MT at the base of the convection zone is positive at the poles and negative at
the equator. A rising MT torque at higher latitudes causes the poles to
speed-up, whereas a declining negative MT torque at the lower latitudes causes
the equator to slow-down. These changes in the zonal flows propagate through
the convection zone up to the surface. Additionally, our results suggest that
it is the magnetic field at the tachocline that modulates the amplitude of the
surface meridional flow rather than the opposite as assumed by flux-transport
dynamo models of the solar cycle.


title: Asymptotic results on Klazar set partition avoidance

abstract:
  We establish asymptotic bounds for the number of partitions of $[n]$ avoiding
a given partition in Klazar's sense, obtaining the correct answer to within an
exponential for the block case. This technique also enables us to establish a
general lower bound. Additionally, we consider a graph theoretic restatement of
partition avoidance problems, and propose several conjectures.


title:
Statistical Guarantees for Estimating the Centers of a Two-component
  Gaussian Mixture by EM

abstract:
  Recently, a general method for analyzing the statistical accuracy of the EM
algorithm has been developed and applied to some simple latent variable models
[Balakrishnan et al. 2016]. In that method, the basin of attraction for valid
initialization is required to be a ball around the truth. Using Stein's Lemma,
we extend these results in the case of estimating the centers of a
two-component Gaussian mixture in $d$ dimensions. In particular, we
significantly expand the basin of attraction to be the intersection of a half
space and a ball around the origin. If the signal-to-noise ratio is at least a
constant multiple of $ \sqrt{d\log d} $, we show that a random initialization
strategy is feasible.


title:
Markov Processes on the Duals to Infinite-Dimensional Classical Lie
  Groups

abstract:
  We construct a four parameter (z, z', a, b) family of Markov dynamics that
preserve the z-measures on the boundary of the branching graph for classical
Lie groups of type B, C, D. Our guiding principle is the "method of
intertwiners" used previously in [7] to construct Markov processes that
preserve the zw-measures.


title:
Computing the Independence Polynomial: from the Tree Threshold down to
  the Roots

abstract:
  We study an algorithm for approximating the multivariate independence
polynomial $Z(\mathbf{z})$, with negative and complex arguments, an object that
has strong connections to combinatorics and to statistical physics. In
particular, the independence polynomial with negative arguments,
$Z(-\mathbf{p})$, determines the Shearer region, the maximal region of
probabilities to which the Lovasz Local Lemma (LLL) can be extended (Shearer
1985). In statistical physics, complex zeros of the independence polynomial
relate to existence of phase transitions.
  Our main result is a deterministic algorithm to compute approximately the
independence polynomial in any root-free complex polydisc centered at the
origin. Our algorithm is essentially the same as Weitz's algorithm for positive
parameters up to the tree uniqueness threshold, and the core of our analysis is
a novel multivariate form of the correlation decay technique, which can handle
non-uniform complex parameters. In particular, in the univariate real setting
our work implies that Weitz's algorithm works in an interval between two
critical points $(\lambda'_c(d), \lambda_c(d))$, and outside of this interval
an approximation of $Z(\mathbf{z})$ is known to be NP-hard.
  As an application, we give a sub-exponential time algorithm for testing
approximate membership in the Shearer region. We also give a new rounding based
deterministic algorithm for Shearer's lemma (an extension of the LLL), which,
however, runs in sub-exponential time. On the hardness side, we prove that
evaluating $Z(\mathbf{z})$ at an arbitrary point in Shearer's region, and
testing membership in Shearer's region, are #P-hard problems. We also establish
the best possible dependence of the exponent of the run time of Weitz's
correlation decay technique in the negative regime on the distance to the
boundary of the Shearer region.


title: Can we prescribe the physical parameters of multiple black holes?

abstract:
  The parabolic-hyperbolic form of the constraints and superposed Kerr-Schild
black holes have already been used to provide a radically new initialization of
binary black hole configurations. The method generalizes straightforwardly to
multiple black hole systems. This paper is to verify that each of the global
Arnowitt-Deser-Misner quantities of the constructed multiple black hole initial
data can always be prescribed, as desired, in advance of solving the
constraints. These global charges are shown to be uniquely determined by the
physical parameters of the involved individual Kerr-Schild black holes.


title:
Flat structures on Frobenius Manifolds in the case of irrelevant
  deformations

abstract:
  In this paper we use the recently suggested conjecture about the integral
representation for the flat coordinates on Frobenius manifolds, connected with
the isolated singularities, to compute the flat coordinates and Saito primitive
form on the space of the deformations of Gepner chiral ring
$\widehat{SU}(3)_4$. We verify this conjecture comparing the expressions for
the flat coordinates obtained from the conjecture with the one found by direct
computation. The considered case is of a particular interest since together
with the relevant and marginal deformations it has one irrelevant deformation.


title: Saturation in inclusive production beyond leading logarithm accuracy

abstract:
  We review recent progress on the calculations on the inclusive forward hadron
production within the saturation formalism. After introducing the concept of
perturbative parton saturation and nonlinear evolution we discuss the formalism
for the forward hadron production at high energy in the leading and
next-to-leading order. Numerical results are presented and compared with the
experimental data on forward hadron production in $dA$ and $pA$. We discuss the
problem of the negativity of the NLO cross section at high transverse momenta,
study its origin in detail and present possible improvements which include the
corrected kinematics and the suitable choice of the rapidity cutoff.


title: Enforcing Biconnectivity in Multi-robot Systems

abstract:
  Connectivity maintenance is an essential task in multi-robot systems and it
has received a considerable attention during the last years. A connected system
can be broken into two or more subsets simply if a single robot fails. A more
robust communication can be achieved if the network connectivity is guaranteed
in the case of one-robot failures. The resulting network is called biconnected.
In \cite{Zareh2016biconnectivitycheck}, we presented a criterion for
biconnectivity check, which basically determines a lower bound on the
third-smallest eigenvalue of the Laplacian matrix. In this paper, we introduce
a decentralized gradient-based protocol to increase the value of the
third-smallest eigenvalue of the Laplacian matrix, when the biconnectivity
check fails. We also introduce a decentralized algorithm to estimate the
eigenvectors of the Laplacian matrix, which are used for defining the gradient.
Simulations show the effectiveness of the theoretical findings.


title: Delta Epsilon Alpha Star: A PAC-Admissible Search Algorithm

abstract:
  Delta Epsilon Alpha Star is a minimal coverage, real-time robotic search
algorithm that yields a moderately aggressive search path with minimal
backtracking. Search performance is bounded by a placing a combinatorial bound,
epsilon and delta, on the maximum deviation from the theoretical shortest path
and the probability at which further deviations can occur. Additionally, we
formally define the notion of PAC-admissibility -- a relaxed admissibility
criteria for algorithms, and show that PAC-admissible algorithms are better
suited to robotic search situations than epsilon-admissible or strict
algorithms.


title:
Fine structure of the age-chromospheric activity relation in solar-type
  stars I: The Ca II infrared triplet: Absolute flux calibration

abstract:
  Strong spectral lines are useful indicators of stellar chromospheric
activity. They are physically linked to the convection efficiency, differential
rotation, and angular momentum evolution and are a potential indicator of age.
However, for ages > 2 Gyr, the age-activity relationship remains poorly
constrained thus hampering its full application. The Ca II infrared triplet
(IRT lines) has been poorly studied compared to classical chromospheric
indicators. We report in this paper absolute chromospheric fluxes in the three
Ca II IRT lines, based on a new calibration tied to up-to-date model
atmospheres. We obtain the Ca II IRT absolute fluxes for 113 FGK stars from
high signal-to-noise ratio and high-resolution spectra covering an extensive
domain of chromospheric activity levels. We perform an absolute continuum flux
calibration for the Ca II IRT lines anchored in atmospheric models calculated
as an explicit function of effective temperatures, metallicity, and gravities
avoiding the degeneracy present in photometric continuum calibrations based
solely on color indices. The internal uncertainties achieved for continuum
absolute flux calculations are 2\% of the solar chromospheric flux, one order
of magnitude lower than photometric calibrations. We gauge the impact of
observational errors on the final chromospheric fluxes due to the absolute
continuum flux calibration and find that $T_{\rm eff}$ uncertainties are
properly mitigated by the photospheric correction leaving [Fe/H] as the
dominating factor in the chromospheric flux uncertainty. Across the FGK
spectral types, the Ca II IRT lines are sensitive to chromospheric activity.
The reduced internal uncertainties reported here enable us to build a new
chromospheric absolute flux scale and explore the age-activity relation from
the active regime down to very low activity levels and a wide range of $T_{\rm
eff}$, mass, [Fe/H], and age.


title: Detecting Sarcasm in Multimodal Social Platforms

abstract:
  Sarcasm is a peculiar form of sentiment expression, where the surface
sentiment differs from the implied sentiment. The detection of sarcasm in
social media platforms has been applied in the past mainly to textual
utterances where lexical indicators (such as interjections and intensifiers),
linguistic markers, and contextual information (such as user profiles, or past
conversations) were used to detect the sarcastic tone. However, modern social
media platforms allow to create multimodal messages where audiovisual content
is integrated with the text, making the analysis of a mode in isolation
partial. In our work, we first study the relationship between the textual and
visual aspects in multimodal posts from three major social media platforms,
i.e., Instagram, Tumblr and Twitter, and we run a crowdsourcing task to
quantify the extent to which images are perceived as necessary by human
annotators. Moreover, we propose two different computational frameworks to
detect sarcasm that integrate the textual and visual modalities. The first
approach exploits visual semantics trained on an external dataset, and
concatenates the semantics features with state-of-the-art textual features. The
second method adapts a visual neural network initialized with parameters
trained on ImageNet to multimodal sarcastic posts. Results show the positive
effect of combining modalities for the detection of sarcasm across platforms
and methods.


title: Isometric Reeb flow in complex hyperbolic quadrics

abstract:
  We classify real hypersurfaces with isometric Reeb flow in the complex
hyperbolic quadrics ${Q^*}^{m} = SO^{o}_{2,m}/SO_mSO_2$, $m \geq 3$. We show
that $m$ is even, say $m = 2k$, and any such hypersurface becomes an open part
of a tube around a $k$-dimensional complex hyperbolic space ${\mathbb C}H^k$
which is embedded canonically in ${Q^*}^{2k}$ as a totally geodesic complex
submanifold or a horosphere whose center at infinity is $\frak A$-isotropic
singular. As a consequence of the result, we get the non-existence of real
hypersurfaces with isometric Reeb flow in odd-dimensional complex quadrics
${Q^*}^{2k+1}$, $k \geq 1$.


title: Semi-Fragile Image Authentication based on CFD and 3-Bit Quantization

abstract:
  There is a great adventure of watermarking usage in the context of
conventional authentication since it does not require additional storage space
for supplementary metadata. However JPEG compression, being a conventional
method to compress images, leads to exact authentication breaking. We discuss a
semi-fragile watermarking system for digital images tolerant to JPEG/JPEG2000
compression. Recently we have published a selective authentication method based
on Zernike moments. But unfortunately it has large computational complexity and
not sufficiently good detection of small image modifications. In the current
paper it is proposed (in contrast to Zernike moments approach) the usage of
image finite differences and 3-bit quantization as the main technique. In order
to embed a watermark (WM) into the image, some areas of the Haar wavelet
transform coefficients are used. Simulation results show a good resistance of
this method to JPEG compression with $\mbox{\rm CR}\leq 30\%$ (Compression
Ratio), high probability of small image modification recognition, image quality
assessments $\mbox{\rm PSNR}\geq 40$ (Peak signal-to-noise ratio) dB and
$\mbox{\rm SSIM}\geq 0.98$ (Structural Similarity Index Measure) after
embedding and lower computation complexity of WM embedding and extraction. All
these properties qualify this approach as effective.


title: Online Adaptation of Deep Architectures with Reinforcement Learning

abstract:
  Online learning has become crucial to many problems in machine learning. As
more data is collected sequentially, quickly adapting to changes in the data
distribution can offer several competitive advantages such as avoiding loss of
prior knowledge and more efficient learning. However, adaptation to changes in
the data distribution (also known as covariate shift) needs to be performed
without compromising past knowledge already built in into the model to cope
with voluminous and dynamic data. In this paper, we propose an online stacked
Denoising Autoencoder whose structure is adapted through reinforcement
learning. Our algorithm forces the network to exploit and explore favourable
architectures employing an estimated utility function that maximises the
accuracy of an unseen validation sequence. Different actions, such as Pool,
Increment and Merge are available to modify the structure of the network. As we
observe through a series of experiments, our approach is more responsive,
robust, and principled than its counterparts for non-stationary as well as
stationary data distributions. Experimental results indicate that our algorithm
performs better at preserving gained prior knowledge and responding to changes
in the data distribution.


title:
Unipotent invariants of filtered representations of quivers and the
  isospectral Hilbert scheme

abstract:
  Given any finite quiver, we consider a complete flag of vector spaces over
each vertex. Consider the unipotent invariant subalgebra of the coordinate ring
of the filtered quiver representation subspace. We prove that the dimension of
the algebraic variety of the unipotent invariant subalgebra is finite. We also
construct an ADHM analog for the Borel subalgebra setting, showing its
birationality to the isospectral Hilbert scheme. Quiver-graded Steinberg
varieties, quantum Hamiltonian reduction, and deformation quantization
constructions for the nonreductive setting are discussed, ending with open
problems.


title:
Self-consistent collective coordinate for reaction path and inertial
  mass

abstract:
  We propose a numerical method to determine the optimal collective reaction
path for the nucleus-nucleus collision, based on the adiabatic self-consistent
collective coordinate (ASCC) method. We use an iterative method combining the
imaginary-time evolution and the finite amplitude method, for the solution of
the ASCC coupled equations. It is applied to the simplest case, the
$\alpha-\alpha$ scattering. We determine the collective path, the potential,
and the inertial mass. The results are compared with other methods, such as the
constrained Hartree-Fock method, the Inglis's cranking formula, and the
adiabatic time-dependent Hartree-Fock (ATDHF) method.


title: Exponential Mixing and Smooth Classification of Commuting Expanding Maps

abstract:
  We show that genuinely higher rank expanding actions of abelian semi-groups
on compact manifolds are $C^{\infty}$-conjugate to affine actions on
infra-nilmanifolds. This is based on the classification of expanding
diffeomorphisms up to \holder conjugacy by Gromov and Shub, and is similar to
recent work on smooth classification of higher rank Anosov actions on tori and
nilmanifolds. To prove regularity of the conjugacy in the higher rank setting,
we establish exponential mixing of solenoid actions induced from semi-group
actions by nilmanifold endomorphisms, a result of independent interest. We then
proceed similar to the case of higher rank Anosov actions.


title: Explicit formulas for the spectral side of the trace formula of SL(2)

abstract:
  The continuous spectrum to the spectral side of the Arthur-Selberg trace
formula is described in terms of intertwining operators, whose normalising
factors involve quotients of $L$-functions. In this paper, we derive two
expressions in the case of SL(2) over a number field in terms of the
Riemann-Weil explicit formula: as a sum over zeroes of the associated
$L$-functions, and as a sum of adelic distributions on Weil groups. As an
application, we obtain an expression for a lower bound for the sums over zeroes
with respect to the truncation parameter for Eisenstein series.


title:
Maximum entropy generation rate density and its application to
  microstructural evolution

abstract:
  A solidification model based on the principle of maximum entropy production
rate (MEPR) is considered for the study of pure metals. The approach leads to
the development of a breakdown criterion which is able to account for the
solidification velocity and solid-liquid interface (SLI) thickness. The
quantitative knowledge of the SLI thickness and the maximum entropy generation
rate density obtained at breakdown gives an insight about the structure of the
SLI during solid to liquid phase transformation. The formation of facet and
non-facet morphology, and their transitions are accounted for, which is a
function of solidification velocity, heat of fusion, density and the
crystallographic growth plane.


title:
Quantum Monte Carlo study of the itinerant-localized model of strongly
  correlated electrons: Spin-spin correlation functions

abstract:
  We perform quantum Monte Carlo simulations of the itinerant-localized
periodic Kondo-Heisenberg model for the underdoped cuprates to calculate the
associated spin correlation functions. The strong electron correlations are
shown to play a key role in the abrupt destruction of the quasi long-range
antiferromagnetic order in the lightly doped regime.


title:
A Probabilistic Approach to the Zero-Mass Limit Problem for Three
  Magnetic Relativistic Schrodinger Heat Semigroups

abstract:
  We consider three magnetic relativistic Schr\"odinger operators which
correspond to the same classical symbol $\sqrt{(\xi-A(x))^2+m^2}+V(x)$ and
whose heat semigroups admit the Feynman-Kac-It\^o type path integral
representation $E[e^{-S^m(x,t, X)}g(x+X(t))]$. Using these representations, we
prove the convergence of these heat semigroups when the mass--parameter $m$
goes to zero. Its proof reduces to the convergence of $e^{-S^m(x,t;X)}$, which
yields a limit theorem for exponentials of semimartingales as functionals of
L\'evy processes $X$.


title: A simple preprocessing algorithm for semidefinite programming

abstract:
  We propose a very simple preprocessing algorithm for semidefinite
programming. Our algorithm inspects the constraints of the problem, deletes
redundant rows and columns in the constraints, and reduces the size of the
variable matrix. It often detects infeasibility. Our algorithm does not rely on
any optimization solver: the only subroutine it needs is Cholesky
factorization, hence it can be implemented with a few lines of code in machine
precision. We present computational results on a set of problems arising mostly
from polynomial optimization.


title: Uncovering Voice Misuse Using Symbolic Mismatch

abstract:
  Voice disorders affect an estimated 14 million working-aged Americans, and
many more worldwide. We present the first large scale study of vocal misuse
based on long-term ambulatory data collected by an accelerometer placed on the
neck. We investigate an unsupervised data mining approach to uncovering latent
information about voice misuse.
  We segment signals from over 253 days of data from 22 subjects into over a
hundred million single glottal pulses (closures of the vocal folds), cluster
segments into symbols, and use symbolic mismatch to uncover differences between
patients and matched controls, and between patients pre- and post-treatment.
Our results show significant behavioral differences between patients and
controls, as well as between some pre- and post-treatment patients. Our
proposed approach provides an objective basis for helping diagnose behavioral
voice disorders, and is a first step towards a more data-driven understanding
of the impact of voice therapy.


title: The Extreme Ultraviolet Variability of Quasars

abstract:
  We study the extreme ultraviolet (EUV) variability (rest frame wavelengths
500 - 920 $\AA$) of high luminosity quasars using HST (low to intermediate
redshift sample) and SDSS (high redshift sample) archives. The combined HST and
SDSS data indicates a much more pronounced variability when the sampling time
between observations in the quasar rest frame is $> 2\times 10^{7}$ sec
compared to $< 1.5\times 10^{7}$ sec. Based on an excess variance analysis, for
time intervals $< 2\times 10^{7}$ sec in the quasar rest frame, $10\%$ of the
quasars (4/40) show evidence of EUV variability. Similarly, for time intervals
$>2\times 10^{7}$ sec in the quasar rest frame, $55\%$ of the quasars (21/38)
show evidence of EUV variability. The propensity for variability does not show
any statistically significant change between $2.5\times 10^{7}$ sec and
$3.16\times 10^{7}$ sec (1 yr). The temporal behavior is one of a threshold
time interval for significant variability as opposed to a gradual increase on
these time scales. A threshold time scale can indicate a characteristic spatial
dimension of the EUV region. We explore this concept in the context of the slim
disk models of accretion. We find that for rapidly spinning black holes, the
radial infall time to the plunge region of the optically thin surface layer of
the slim disk that is responsible for the preponderance of the EUV flux
emission (primarily within 0 - 7 black hole radii from the inner edge of the
disk) is consistent with the empirically determined variability time scale.


title:
On the rate of convergence of strong Euler approximation for SDEs driven
  by Levy processes

abstract:
  SDE driven by an $\alpha $-stable process, $\alpha \in \lbrack 1,2),$ with
Lipshitz continuous coefficient and $\beta $-H\"older drift is considered. The
existence and uniqueness of a strong solution is proved when $\beta >1-\alpha
/2$ by showing that it is $L_{p}$-limit of Euler approximations. The
$L_{p}$-error (rate of convergence) is obtained for a nondegenerate truncated
and nontruncated driving process. The rate in the case of Lipshitz continuous
coefficients is derived as well.


title:
Spin-glass behavior and pyroelectric anomalies in a new lithium-based
  oxide, Li3FeRuO5

abstract:
  The results of dc and ac magnetization, heat-capacity, 57Fe Moessbauer
spectroscopy, dielectric, pyroelectric current and isothermal
magneto-capacitance measurements on a recently reported lithium-based oxide,
Li3FeRuO6, related to LiCoO2-type rhombohedral structure (space group, R-3m)
are presented. The results reveal that the compound undergoes spin-glass
freezing below 15 K. There is a peak around 34 K in pyroelectric data, which
can not be attributed to ferroelectricity, but to the phenomenon of thermally
stimulated depolarization current. As revealed by magnetocapacitance data above
and below magnetic ordering temperature, magnetic and electric dipoles appear
to be coupled, thereby offering evidence for magnetodielectric coupling.


title: Vehicle Routing Problems for Drone Delivery

abstract:
  Unmanned aerial vehicles, or drones, have the potential to significantly
reduce the cost and time of making last-mile deliveries and responding to
emergencies. Despite this potential, little work has gone into developing
vehicle routing problems (VRPs) specifically for drone delivery scenarios.
Existing VRPs are insufficient for planning drone deliveries: either multiple
trips to the depot are not permitted, leading to solutions with excess drones,
or the effect of battery and payload weight on energy consumption is not
considered, leading to costly or infeasible routes. We propose two multi-trip
VRPs for drone delivery that address both issues. One minimizes costs subject
to a delivery time limit, while the other minimizes the overall delivery time
subject to a budget constraint. We mathematically derive and experimentally
validate an energy consumption model for multirotor drones, demonstrating that
energy consumption varies approximately linearly with payload and battery
weight. We use this approximation to derive mixed integer linear programs for
our VRPs. We propose a cost function that considers our energy consumption
model and drone reuse, and apply it in a simulated annealing (SA) heuristic for
finding sub-optimal solutions to practical scenarios. To assist drone delivery
practitioners with balancing cost and delivery time, the SA heuristic is used
to show that the minimum cost has an inverse exponential relationship with the
delivery time limit, and the minimum overall delivery time has an inverse
exponential relationship with the budget. Numerical results confirm the
importance of reusing drones and optimizing battery size in drone delivery
VRPs.


title: Three dimensional tropical correspondence formula

abstract:
  A tropical curve in $\mathbb R^{3}$ contributes to Gromov-Witten invariants
in all genus.
  Nevertheless, we present a simple formula for how a given tropical curve
contributes to Gromov-Witten invariants when we encode these invariants in a
generating function with exponents of $\lambda$ recording Euler characteristic.
Our main modification from the known tropical correspondence formula for
rational curves is as follows: a trivalent vertex, which before contributed a
factor of $n$ to the count of zero-genus holomorphic curves, contributes a
factor of $2\sin(n\lambda/2)$.
  We explain how to calculate relative Gromov-Witten invariants using this
tropical correspondence formula, and how to obtain the absolute Gromov-Witten
and Donaldson-Thomas invariants of some $3$-dimensional toric manifolds
including $\mathbb CP^{3}$. The tropical correspondence formula counting
Donaldson-Thomas invariants replaces $n$ by
$i^{-(1+n)}q^{n/2}+i^{1+n}q^{-n/2}$.

categories: math.SG math-ph math.AG math.CO math.DG math.MP


title:
SANTIAGO: Spine Association for Neuron Topology Improvement and Graph
  Optimization

abstract:
  Developing automated and semi-automated solutions for reconstructing wiring
diagrams of the brain from electron micrographs is important for advancing the
field of connectomics. While the ultimate goal is to generate a graph of neuron
connectivity, most prior automated methods have focused on volume segmentation
rather than explicit graph estimation. In these approaches, one of the key,
commonly occurring error modes is dendritic shaft-spine fragmentation.
  We posit that directly addressing this problem of connection identification
may provide critical insight into estimating more accurate brain graphs. To
this end, we develop a network-centric approach motivated by biological priors
image grammars. We build a computer vision pipeline to reconnect fragmented
spines to their parent dendrites using both fully-automated and semi-automated
approaches. Our experiments show we can learn valid connections despite
uncertain segmentation paths. We curate the first known reference dataset for
analyzing the performance of various spine-shaft algorithms and demonstrate
promising results that recover many previously lost connections. Our automated
approach improves the local subgraph score by more than four times and the full
graph score by 60 percent. These data, results, and evaluation tools are all
available to the broader scientific community. This reframing of the
connectomics problem illustrates a semantic, biologically inspired solution to
remedy a major problem with neuron tracking.


title:
Supernovae and Single-Year Anomalies in the Atmospheric Radiocarbon
  Record

abstract:
  Single-year spikes in radiocarbon production are caused by intense bursts of
radiation from space. Supernovae emit both high-energy particle and
electromagnetic radiation, but it is the latter that is most likely to strike
the atmosphere all at once and cause a surge in 14C production. In the 1990s,
it was claimed that the supernova in 1006 CE produced exactly this effect. With
the 14C spikes in the years 775 and 994 CE now attributed to extreme solar
events, attention has returned to the question of whether historical supernovae
are indeed detectable using annual 14C measurements. Here, we combine new and
existing measurements over six documented and putative supernovae, and conclude
that no such astrophysical event has yet left a distinct imprint on the past
atmospheric 14C record.


title:
Evolution of star cluster systems in isolated galaxies: first results
  from direct $N$-body simulations

abstract:
  The evolution of star clusters is largely affected by the tidal field
generated by the host galaxy. It is thus in principle expected that under the
assumption of an "universal" initial cluster mass function the properties of
the evolved present-day mass function of star cluster systems should show a
dependency on the properties of the galactic environment in which they evolve.
To explore this expectation a sophisticated model of the tidal field is
required in order to study the evolution of star cluster systems in realistic
galaxies. Along these lines, in the present work we first describe a method
developed for coupling $N$-body simulations of galaxies and star clusters. We
then generate a database of galaxy models along the Hubble sequence and
calibrate evolutionary equations to the results of direct $N$-body simulations
of star clusters in order to predict the clusters' mass evolution as function
of the galactic environment. We finally apply our methods to explore the
properties of evolved "universal" initial cluster mass functions and any
dependence on the host galaxy morphology and mass distribution. The preliminary
results show that an initial power-law distribution of the masses "universally"
evolves into a log-normal distribution, with the properties correlated with the
stellar mass and stellar mass density density of the host galaxy.