title:
The Impact of Modeling Errors on Interferometer Calibration for 21 cm
  Power Spectra

abstract:
  We study the impact of sky-based calibration errors from source mismodeling
on 21\,cm power spectrum measurements with an interferometer and propose a
method for suppressing their effects. While emission from faint sources that
are not accounted for in calibration catalogs is believed to be spectrally
smooth, deviations of true visibilities from model visibilities are not, due to
the inherent chromaticity of the interferometer's sky-response (the "wedge").
Thus, unmodeled foregrounds, below the confusion limit of many instruments,
introduce frequency structure into gain solutions on the same line-of-sight
scales on which we hope to observe the cosmological signal. We derive analytic
expressions describing these errors using linearized approximations of the
calibration equations and estimate the impact of this bias on measurements of
the 21\,cm power spectrum during the Epoch of Reionization (EoR). Given our
current precision in primary beam and foreground modeling, this noise will
significantly impact the sensitivity of existing experiments that rely on
sky-based calibration. Our formalism describes the scaling of calibration with
array and sky-model parameters and can be used to guide future instrument
design and calibration strategy. We find that sky-based calibration that
down-weights long baselines can eliminate contamination in most of the region
outside of the wedge with only a modest increase in instrumental noise.


title: Fluctuations of interlacing sequences

abstract:
  In a series of works published in the 1990-s, Kerov put forth various
applications of the circle of ideas centred at the Markov moment problem to the
limiting shape of random continual diagrams arising in representation theory
and spectral theory. We demonstrate on several examples that his approach is
also adequate to study the fluctuations about the limiting shape.
  In the random matrix setting, we compare two continual diagrams: one is
constructed from the eigenvalues of the matrix and the critical points of its
characteristic polynomial, whereas the second one is constructed from the
eigenvalues of the matrix and those of its principal submatrix. The
fluctuations of the latter diagram were recently studied by Erd\H{o}s and
Schr\"oder; we discuss the fluctuations of the former, and compare the two
limiting processes.
  For Plancherel random partitions, the Markov correspondence establishes the
equivalence between Kerov's central limit theorem for the Young diagram and the
Ivanov--Olshanski central limit theorem for the transition measure. We outline
a combinatorial proof of the latter, and compare the limiting process with the
ones of random matrices.


title: On the Kauffman-Jones polynomial for virtual singular links

abstract:
  We extend the Kamada-Miyazawa polynomial to virtual singular links, which is
valued in $\mathbb{Z}[A^2, A^{-2}, h]$. The decomposition of the resulting
polynomial into two components, one in $\mathbb{Z}[A^2, A^{-2}]$ and the other
in $\mathbb{Z}[A^2, A^{-2}]h$ yields the decomposition of the Kauffman-Jones
polynomial of virtual singular links into two components, one in
$\mathbb{Z}[A^2, A^{-2}]$ and the other in $\mathbb{Z}[A^2, A^{-2}]A^2$, where
both components are invariants for virtual singular links.


title: Open-Ended Visual Question-Answering

abstract:
  This thesis report studies methods to solve Visual Question-Answering (VQA)
tasks with a Deep Learning framework. As a preliminary step, we explore Long
Short-Term Memory (LSTM) networks used in Natural Language Processing (NLP) to
tackle Question-Answering (text based). We then modify the previous model to
accept an image as an input in addition to the question. For this purpose, we
explore the VGG-16 and K-CNN convolutional neural networks to extract visual
features from the image. These are merged with the word embedding or with a
sentence embedding of the question to predict the answer. This work was
successfully submitted to the Visual Question Answering Challenge 2016, where
it achieved a 53,62% of accuracy in the test dataset. The developed software
has followed the best programming practices and Python code style, providing a
consistent baseline in Keras for different configurations.


title: Interplay between magnetism and sodium vacancy ordering in NaxCoO2

abstract:
  Using a combination of low-temperature nanocalorimetry and x-ray diffraction
we identify three temperature regimes characterized by distinct Na ordering
patterns (low temperature up to 290 K, intermediate 290-340 K, and high above
340 K). Through freezing-in of these patterns we establish the two key roles
sodium intercalation plays in the formation of the magnetic ground state:
supplying the proper electron count for in-plane ferromagnetic interaction and
through the 3D sodium ordering providing the interplane antiferromagnetic
exchange path.


title: Character varieties as a tensor product

abstract:
  In this short note we show that representation and character varieties of
discrete groups can be viewed as tensor products of suitable functors over the
PROP of cocommutative Hopf algebras. Such view point has several interesting
applications. First, it gives a straightforward way of deriving the functor
sending a discrete group to the functions on its representation variety, which
leads to representation homology. Second, using a suitable deformation of the
functors involved in this construction, one can obtain deformations of the
representation and character varieties for the fundamental groups of
3-manifolds, and could lead to better understanding of quantum representations
of mapping class groups.


title:
Atomically inspired $k \cdot p$ approach and valley Zeeman effect in
  transition metal dichalcogenide monolayers

abstract:
  We developed a six-band $k \cdot p$ model that describes the electronic
states of monolayer transition metal dichalcogenides (TMDCs) in $K$-valleys.
The set of parameters for the $k \cdot p$ model is uniquely determined by
decomposing tight-binding (TB) models in the vicinity of $K^\pm$-points. First,
we used TB models existing in literature to derive systematic parametrizations
for different materials, including MoS$_2$, WS$_2$, MoSe$_2$ and WSe$_2$. Then,
by using the derived six-band $k \cdot p$ Hamiltonian we calculated effective
masses, Landau levels, and the effective exciton $g$-factor $g_{X^0}$ in
different TMDCs. We showed that TB parameterizations existing in literature
result in small absolute values of $g_{X^0}$, which are far from the
experimentally measured $g_{X^0} \approx -4$. To further investigate this issue
we derived two additional sets of $k \cdot p$ parameters by developing our own
TB parameterizations based on simultaneous fitting of ab-initio calculated,
within the density functional (DFT) and $GW$ approaches, energy dispersion and
the value of $g_{X^0}$. We showed that the change in TB parameters, which only
slightly affects the dispersion of higher conduction and deep valence bands,
may result in a significant increase of $|g_{X^0}|$, yielding
close-to-experiment values of $g_{X^0}$. Such a high parameter sensitivity of
$g_{X^0}$ opens a way to further improvement of DFT and TB models.


title: Bow-shock Pulsar Wind Nebulae Passing Through Density Discontinuities

abstract:
  Bow-shock pulsar wind nebulae are a subset of pulsar wind nebulae that form
when the pulsar has high velocity due to the natal kick during the supernova
explosion. The interaction between the relativistic wind from the fast-moving
pulsar and the interstellar medium produces a bow-shock and a trail, which are
detectable in H$_{\alpha}$ emission. Among such bow-shock pulsar wind nebulae,
the Guitar Nebula stands out for its peculiar morphology, which consists of a
prominent bow-shock head and a series of bubbles further behind. We present a
scenario in which multiple bubbles can be produced when the pulsar encounters a
series of density discontinuities in the ISM. We tested the scenario using 2-D
and 3-D hydrodynamic simulations. The shape of the guitar nebula can be
reproduced if the pulsar traversed a region of declining low density. We also
show that if a pulsar encounters an inclined density discontinuity, it produces
an asymmetric bow-shock head, consistent with observations of the bow-shock of
the millisecond pulsar J2124-3358.


title:
Analysis of the conditional average and conditional variance of
  dissipated energy in the driven spin-boson model

abstract:
  We investigate the conditional average and the conditional variance of
dissipated energy considering, as a prototypical example, a driven spin-boson
system. We follow a measurement protocol in which the spin is prepared in a
certain initial state before undergoing a periodic driving. Subsequently, the
spin is projected onto a post-selected final state. We compare the conditional
average of dissipated energy to the lower bound which directly follows from the
well known fluctuation relations. We further report that a special selection of
the initial (pre-selected) and final (post-selected) spin states leads to an
enhanced energy emission with simultaneous noise suppression at driving times
of order of the relaxation time.


title: Combinatorial Models for the Variety of Complete Quadrics

abstract:
  We develop several combinatorial models that are useful in the study of the
$SL_n$-variety $\mathcal{X}$ of complete quadrics. Barred permutations
parameterize the fixed points of the action of a maximal torus $T$ of $SL_n$,
while $\mu$-involutions parameterize the orbits of a Borel subgroup of $SL_n$.
Using these combinatorial objects, we characterize the $T$-stable curves and
surfaces on $\mathcal{X}$, compute the $T$-equivariant $K$-theory of
$\mathcal{X}$, and describe a Bia{\l}ynicki-Birula cell decomposition for
$\mathcal{X}$. Furthermore, we give a computational characterization of the
Bruhat order on Borel orbits in $\mathcal{X}$.


title: Physical properties of KMgBi single crystals

abstract:
  KMgBi single crystals are grown by using the Bi flux successfully. KMgBi
shows semiconducting behavior with a metal-semiconductor transition at high
temperature region and a resistivity plateau at low temperature region,
suggesting KMgBi could be a topological insulator with a very small band gap.
Moreover, KMgBi exhibits multiband feature with strong temperature dependence
of carrier concentrations and mobilities.


title: Invariance principles for random sums of random variables

abstract:
  This note investigates invariance principles for sums of N(nt) iid radom
variables, where n is an integer, t is a positive real number and N(u) is a
stochastic process with nonnegative integer values. We show that the sequence
of sums of these random variables denoted S(n,t), when appropriately centered
and normalized, weakly converges to a Gaussian process. We give sufficient
conditions depending on the expectation of N(nt) which allows to rescale S(n,t)
into a stochastic S(n,a(t)) weakly converging to a Brownian motion.


title:
Topological Entropy Bounds for Switched Linear Systems with Lie
  Structure

abstract:
  In this thesis, we provide an initial investigation into bounds for
topological entropy of switched linear systems. Entropy measures, roughly, the
information needed to describe the behavior of a system with finite precision
on finite time horizons, in the limit. After working out entropy computations
in detail for the scalar switched case, we review the linear time-invariant
nonscalar case, and extend to the nonscalar switched case. We assume some
commutation relations among the matrices of the switched system, namely
solvability, define an upper average time of activation quantity and use it to
provide an upper bound on the entropy of the switched system in terms of the
eigenvalues of each subsystem.


title: Data preparation for asteroseismology with TESS

abstract:
  The Transiting Exoplanet Survey Satellite (TESS) is a NASA Astrophysics
Explorer mission. Following its scheduled launch in 2017, TESS will focus on
detecting exoplanets around the nearest and brightest stars in the sky, for
which detailed follow-up observations are possible. TESS will, as the NASA
Kepler mission, include a asteroseismic program that will be organized within
the TESS Asteroseismic Science Consortium (TASC), building on the success of
the Kepler Asteroseismic Science Consortium (KASC). Within TASC data for
asteroseismic analysis will be prepared by the TASC Working Group 0 (WG-0), who
will facilitate data to the community via the TESS Asteroseismic Science
Operations Center (TASOC), again building on the success of the corresponding
KASOC platform for Kepler. Here, we give an overview of the steps being taken
within WG-0 to prepare for the upcoming TESS mission.


title:
Nonparametric Bayesian inference of the microcanonical stochastic block
  model

abstract:
  A principled approach to characterize the hidden structure of networks is to
formulate generative models, and then infer their parameters from data. When
the desired structure is composed of modules or "communities", a suitable
choice for this task is the stochastic block model (SBM), where nodes are
divided into groups, and the placement of edges is conditioned on the group
memberships. Here, we present a nonparametric Bayesian method to infer the
modular structure of empirical networks, including the number of modules and
their hierarchical organization. We focus on a microcanonical variant of the
SBM, where the structure is imposed via hard constraints, i.e. the generated
networks are not allowed to violate the patterns imposed by the model. We show
how this simple model variation allows simultaneously for two important
improvements over more traditional inference approaches: 1. Deeper Bayesian
hierarchies, with noninformative priors replaced by sequences of priors and
hyperpriors, that not only remove limitations that seriously degrade the
inference on large networks, but also reveal structures at multiple scales; 2.
A very efficient inference algorithm that scales well not only for networks
with a large number of nodes and edges, but also with an unlimited number of
modules. We show also how this approach can be used to sample modular
hierarchies from the posterior distribution, as well as to perform model
selection. We discuss and analyze the differences between sampling from the
posterior and simply finding the single parameter estimate that maximizes it.
Furthermore, we expose a direct equivalence between our microcanonical approach
and alternative derivations based on the canonical SBM.


title:
Approximating Rectangles by Juntas and Weakly-Exponential Lower Bounds
  for LP Relaxations of CSPs

abstract:
  We show that for constraint satisfaction problems (CSPs), sub-exponential
size linear programming relaxations are as powerful as $n^{\Omega(1)}$-rounds
of the Sherali-Adams linear programming hierarchy. As a corollary, we obtain
sub-exponential size lower bounds for linear programming relaxations that beat
random guessing for many CSPs such as MAX-CUT and MAX-3SAT. This is a
nearly-exponential improvement over previous results, previously, it was only
known that linear programs of size $n^{o(\log n)}$ cannot beat random guessing
for any CSP (Chan-Lee-Raghavendra-Steurer 2013).
  Our bounds are obtained by exploiting and extending the recent progress in
communication complexity for "lifting" query lower bounds to communication
problems. The main ingredient in our results is a new structural result on
"high-entropy rectangles" that may of independent interest in communication
complexity.


title: Disk heating and bending instability in galaxies with counterrotation

abstract:
  With the help of high-resolution long-slit and integral-field spectroscopy
observations, the number of confirmed cases of galaxies with counterrotation is
increasing rapidly. The evolution of such counterrotating galaxies remains far
from being well understood. In this paper we study the dynamics of
counterrotating collisionless stellar disks by means of $N$-body simulations.
We show that, in the presence of counterrotation, an otherwise gravitationally
stable disk can naturally generate bending waves accompanied by strong disk
heating across the disk plane, that is in the vertical direction. Such
conclusion is found to hold even for dynamically warm systems with typical
values of the initial vertical-to-radial velocity dispersion ratio $\sigma_{\rm
z}/\sigma_{\rm R} \approx 0.5$, for which the role of pressure anisotropy
should be unimportant. We note that, during evolution, the $\sigma_{\rm
z}/\sigma_{\rm R}$ ratio tends to rise up to values close to unity in the case
of locally Jeans-stable disks, whereas in disks that are initially
Jeans-unstable it may reach even higher values, especially in the innermost
regions. This unusual behavior of the $\sigma_{\rm z}/\sigma_{\rm R}$ ratio in
galaxies with counterrotation appears not to have been noticed earlier. Our
investigations of systems made of two counterrotating components with different
mass-ratios suggest that even apparently normal disk galaxies (i.e., with a
minor counterrotating component so as to escape detection in current
observations) might be subject to significant disk heating especially in the
vertical direction.


title: Saccharinity with ccc

abstract:
  Using creature technology, we construct families of Suslin ccc non-sweet
forcing notions $\mathbb Q$ such that $ZFC$ is equiconsistent with $ZF+$"every
set of reals equals a Borel set modulo the $(\leq \aleph_1)$-closure of the
null ideal associated with $\mathbb Q$"+"there is an $\omega_1$-sequence of
distinct reals".


title: Multi-Objective Deep Reinforcement Learning

abstract:
  We propose Deep Optimistic Linear Support Learning (DOL) to solve
high-dimensional multi-objective decision problems where the relative
importances of the objectives are not known a priori. Using features from the
high-dimensional inputs, DOL computes the convex coverage set containing all
potential optimal solutions of the convex combinations of the objectives. To
our knowledge, this is the first time that deep reinforcement learning has
succeeded in learning multi-objective policies. In addition, we provide a
testbed with two experiments to be used as a benchmark for deep multi-objective
reinforcement learning.


title: Population patterns in World's administrative units

abstract:
  While there has been an extended discussion concerning city population
distribution, little has been said about administrative units. Even though
there might be a correspondence between cities and administrative divisions,
they are conceptually different entities and the correspondence breaks as
artificial divisions form and evolve. In this work we investigate the
population distribution of second level administrative units for 150 countries
and propose the Discrete Generalized Beta Distribution (DGBD) rank-size
function to describe the data. After testing the goodness of fit of this two
parameter function against power law, which is the most common model for city
population, DGBD is a good statistical model for 73% of our data sets and
better than power law in almost every case. Particularly, DGBD is better than
power law for fitting country population data. The fitted parameters of this
function allow us to construct a phenomenological characterization of countries
according to the way in which people are distributed inside them. We present a
computational model to simulate the formation of administrative divisions and
give numerical evidence that DGBD arises from it. This model along with the
DGBD function prove adequate to reproduce and describe local unit evolution and
its effect on population distribution.


title:
Empirical scaling of the length of the longest increasing subsequences
  of random walks

abstract:
  We provide Monte Carlo estimates of the scaling of the length $L_{n}$ of the
longest increasing subsequences of $n$-steps random walks for several different
distributions of step lengths, short and heavy-tailed. Our simulations indicate
that, barring possible logarithmic corrections, $L_{n} \sim n^{\theta}$ with
the leading scaling exponent $0.60 \lesssim \theta \lesssim 0.69$ for the
heavy-tailed distributions of step lengths examined, with values increasing as
the distribution becomes more heavy-tailed, and $\theta \simeq 0.57$ for
distributions of finite variance, irrespective of the particular distribution.
The results are consistent with existing rigorous bounds for $\theta$, although
in a somewhat surprising manner. For random walks with step lengths of finite
variance, we conjecture that the correct asymptotic behavior of $L_{n}$ is
given by $\sqrt{n}\ln n$, and also propose the form of the subleading
asymptotics. The distribution of $L_{n}$ was found to follow a simple scaling
form with scaling functions that vary with $\theta$. Accordingly, when the step
lengths are of finite variance they seem to be universal. The nature of this
scaling remains unclear, since we lack a working model, microscopic or
hydrodynamic, for the behavior of the length of the longest increasing
subsequences of random walks.


title: Modal Dependence Logics: Axiomatizations and Model-theoretic Properties

abstract:
  Modal dependence logics are modal logics defined on the basis of team
semantics and have the downward closure property. In this paper, we introduce
sound and complete deduction systems for the major modal dependence logics,
especially those with intuitionistic connectives in their languages. We also
establish a concrete connection between team semantics and single-world
semantics, and show that modal dependence logics can be interpreted as variants
of intuitionistic modal logics.


title: The Mean Metal-line Absorption Spectrum of DLAs in BOSS

abstract:
  We study the mean absorption spectrum of the Damped Lyman alpha population at
$z\sim 2.6$ by stacking normalized, rest-frame shifted spectra of $\sim
27\,000$ DLAs from the DR12 of BOSS/SDSS-III. We measure the equivalent widths
of 50 individual metal absorption lines in 5 intervals of DLA hydrogen column
density, 5 intervals of DLA redshift, and overall mean equivalent widths for an
additional 13 absorption features from groups of strongly blended lines. The
mean equivalent width of low-ionization lines increases with $N_{\rm HI}$,
whereas for high-ionization lines the increase is much weaker. The mean metal
line equivalent widths decrease by a factor $\sim 1.1-1.5$ from $z\sim2.1$ to
$z \sim 3.5$, with small or no differences between low- and high-ionization
species. We develop a theoretical model, inspired by the presence of multiple
absorption components observed in high-resolution spectra, to infer mean metal
column densities from the equivalent widths of partially saturated metal lines.
We apply this model to 14 low-ionization species and to AlIII, SIII, SiIII,
CIV, SiIV, NV and OVI. We use an approximate derivation for separating the
equivalent width contributions of several lines to blended absorption features,
and infer mean equivalent widths and column densities from lines of the
additional species NI, ZnII, CII${}^{*}$, FeIII, and SIV. Several of these mean
column densities of metal lines in DLAs are obtained for the first time; their
values generally agree with measurements of individual DLAs from
high-resolution, high signal-to-noise ratio spectra when they are available.


title: On isomorphism problem for von Neumann flows with one discontinuity

abstract:
  A von Neumann flow is a special flow over an irrational rotation of the
circle and under a piecewise $C^1$ roof function with a non-zero sum of jumps.
We prove that the absolute value of the slope is a (measure theoretic)
invariant in the class of von Neumann special flows with one discontinuity,
i.e. two ergodic von Neumann flows with one discontinuity are not isomorphic if
the slopes of the roof functions have different absolute values, regardless of
the irrational rotation in the base.


title:
The isotopic effects in the scattering and the kinetics of the atomic
  cascade

abstract:
  {\it Ab initio} quantum-mechanical calculations of the differential and
integrated cross sections of the elastic scattering, Stark transitions, and
Coulomb de-excitation at collisions of excited $\mu^- p$ and $\mu^- d$ atoms
with hydrogen isotope atoms in the ground state are performed. The scattering
processes are treated in a unified manner in the framework of the
close-coupling approach. The used basis includes both open and closed channels
corresponding to all exotic atom states with principal quantum numbers from
$n=1$ up to $n_{\rm max}=20$. The energy shifts of $ns$ states due to electron
vacuum polarization and finite nuclear size are taken into account. The
kinetics of atomic cascade of $\mu^- p$ and $\mu^- d$ atoms are studied in a
wide range of relative target densities ($\varphi = 10^{-8} -1$) within the
improved version of the extended cascade model. The results of the numerical
quantum-mechanical calculations of the cross sections for quantum numbers and
kinetic energies of muonic atoms, that are of interest for the detailed cascade
calculations, are used as input data. Initial $(n,l,E)$-distributions of muonic
atoms at the instant of their formation and the target motion are taken into
account explicitly in present cascade calculations. The comparison of the
calculated cross sections, kinetic energy distributions at the instant of the
$np\to 1s$ radiative transitions as well as the absolute and relative $x$-ray
yields for both muonic hydrogen and muonic deuterium reveals the isotopic
effects, which, in principal, may be observed experimentally. The present
results are mainly in very good agreement with experimental data available in
the literature.


title: Egocentric Height Estimation

abstract:
  Egocentric, or first-person vision which became popular in recent years with
an emerge in wearable technology, is different than exocentric (third-person)
vision in some distinguishable ways, one of which being that the camera wearer
is generally not visible in the video frames. Recent work has been done on
action and object recognition in egocentric videos, as well as work on
biometric extraction from first-person videos. Height estimation can be a
useful feature for both soft-biometrics and object tracking. Here, we propose a
method of estimating the height of an egocentric camera without any calibration
or reference points. We used both traditional computer vision approaches and
deep learning in order to determine the visual cues that results in best height
estimation. Here, we introduce a framework inspired by two stream networks
comprising of two Convolutional Neural Networks, one based on spatial
information, and one based on information given by optical flow in a frame.
Given an egocentric video as an input to the framework, our model yields a
height estimate as an output. We also incorporate late fusion to learn a
combination of temporal and spatial cues. Comparing our model with other
methods we used as baselines, we achieve height estimates for videos with a
Mean Average Error of 14.04 cm over a range of 103 cm of data, and
classification accuracy for relative height (tall, medium or short) up to
93.75% where chance level is 33%.


title: Patankar-Type Runge-Kutta Schemes for Linear PDEs

abstract:
  We study the local discretization error of Patankar-type Runge-Kutta methods
applied to semi-discrete PDEs. For a known two-stage Patankar-type scheme the
local error in PDE sense for linear advection or diffusion is shown to be of
the maximal order ${\cal O}(\Delta t^3)$ for sufficiently smooth and positive
exact solutions. However, in a test case mimicking a wetting-drying situation
as in the context of shallow-water flows, this scheme yields large errors in
the drying region. A more realistic approximation is obtained by a modification
of the Patankar approach incorporating an explicit testing stage into the
implicit trapezoidal rule.


title: 3d Quantum Gravity: Coarse-Graining and q-Deformation

abstract:
  The Ponzano-Regge state-sum model provides a quantization of 3d gravity as a
spin foam, providing a quantum amplitude to each 3d triangulation defined in
terms of the 6j-symbol (from the spin-recoupling theory of SU(2)
representations). In this context, the invariance of the 6j-symbol under 4-1
Pachner moves, mathematically defined by the Biedenharn-Elliot identity, can be
understood as the invariance of the Ponzano-Regge model under coarse-graining
or equivalently as the invariance of the amplitudes under the Hamiltonian
constraints. Here we look at length and volume insertions in the
Biedenharn-Elliot identity for the 6j-symbol, derived in some sense as higher
derivatives of the original formula. This gives the behavior of these
geometrical observables under coarse-graining. These new identities turn out to
be related to the Biedenharn-Elliot identity for the q-deformed 6j-symbol and
highlight that the q-deformation produces a cosmological constant term in the
Hamiltonian constraints of 3d quantum gravity.


title: Weighted Cheeger sets are domains of isoperimetry

abstract:
  We consider a generalization of the Cheeger problem in a bounded, open set
$\Omega$ by replacing the perimeter functional with a Finsler-type surface
energy and the volume with suitable powers of a weighted volume. We show that
any connected minimizer $A$ of this weighted Cheeger problem such that
$H^{n-1}(A^{(1)} \cap \partial A)=0$ satisfies a relative isoperimetric
inequality. If $\Omega$ itself is a connected minimizer such that
$H^{n-1}(\Omega^{(1)} \cap \partial \Omega)=0$, then it allows the classical
Sobolev and $BV$ embeddings and the classical $BV$ trace theorem. The same
result holds for any connected minimizer whenever the weights grant the
regularity of perimeter-minimizer sets and $\Omega$ is such that $|\partial
\Omega|=0$ and $H^{n-1}(\Omega^{(1)} \cap \partial \Omega)=0$.


title:
Quasilinear elliptic systems with convex-concave singular terms
  $\Phi\!-\!Laplacian$ operator

abstract:
  This paper deals with existence of positive solutions for a class of
quasilinear elliptic systems involving the $\Phi$-Laplacian operator and
convex-concave singular terms. Our approach is based on the generalized
Galerkin Method along with perturbartion techniques and comparison arguments in
the setting of Orlicz-Sobolev spaces


title:
Correlation-driven topological phase transition from in-plane magnetized
  quantum anomalous Hall to Mott insulating phase in monolayer transition metal
  trichlorides

abstract:
  Based on density functional theory (DFT) calculations, we predict that a
monolayer of OsCl$_3$---a layered material whose interlayer coupling is weaker
than in graphite---possesses a quantum anomalous Hall (QAH) insulating phase
generated by the combination of honeycomb lattice of osmium atoms, their strong
spin-orbit coupling (SOC) and ferromagnetic ground state with {\em in-plane}
easy-axis. The band gap opened by SOC is \mbox{$E_g \simeq 67$ meV} (or
\mbox{$\simeq 191$ meV} if the easy-axis can be tilted out of the plane by an
external electric field), and the estimated Curie temperature of such {\em
anisotropic planar rotator} ferromagnet is $T_\mathrm{C} \lesssim 350$ K. The
Chern number $\mathcal{C}=-1$, generated by the manifold of Os $t_{2g}$ bands
crossing the Fermi energy, signifies the presence of a single chiral edge state
in nanoribbons of finite width, where we further show that edge states are
spatially narrower for zigzag than armchair edges and investigate edge-state
transport in the presence of vacancies at Os sites. Since $5d$ electrons of Os
exhibit {\em both} strong SOC and moderate correlation effects, we employ DFT+U
calculations to show how increasing on-site Coulomb repulsion $U$: gradually
reduces $E_g$ while maintaining $\mathcal{C} = -1$ for $0 < U < U_c$; leads to
metallic phase with $E_g = 0$ at $U_c$; and opens the gap of topologically
trivial Mott insulating phase with $\mathcal{C}=0$ for $U > U_c$.


title:
Self-interaction in the Bopp-Podolsky electrodynamics: Spacetimes with
  angular defects

abstract:
  We consider the self-interaction phenomenon in the framework of the
Bopp-Podolsky electrodynamics. In the present paper, we obtain the
self-interaction potential energy of a charge at rest for the spacetimes with
topological defects of two types: for the axially symmetric spacetime of the
straight cosmic string and the spherically symmetric global monopole spacetime.
It is shown that the behavior of this expression depends essentially on the
angular defect, in spite of the Bopp-Podolsky model parameter, which plays the
role of a scale factor. In contrast with the usual Maxwell electrodynamics, the
self-interaction energy for the Bopp-Podolsky electrodynamics appears to be
finite everywhere and the standard renormalization procedure is not required.


title:
Magnetic cycles in a dynamo simulation of fully convective M-star
  Proxima Centauri

abstract:
  The recent discovery of an Earth-like exoplanet around Proxima Centauri has
shined a spot light on slowly rotating fully convective M-stars. When such
stars rotate rapidly (period $\lesssim 20$ days), they are known to generate
very high levels of activity that is powered by a magnetic field much stronger
than the solar magnetic field. Recent theoretical efforts are beginning to
understand the dynamo process that generates such strong magnetic fields.
However, the observational and theoretical landscape remains relatively
uncharted for fully convective M-stars that rotate slowly. Here we present an
anelastic dynamo simulation designed to mimic some of the physical
characteristics of Proxima Centauri, a representative case for slowly rotating
fully convective M-stars. The rotating convection spontaneously generates
differential rotation in the convection zone which drives coherent magnetic
cycles where the axisymmetric magnetic field repeatedly changes polarity at all
latitudes as time progress. The typical length of the `activity' cycle in the
simulation is about nine years, in good agreement with the recently proposed
activity cycle length of about seven years for Proxima Centauri. Comparing our
results with earlier work, we hypothesis that the dynamo mechanism undergoes a
fundamental change in nature as fully convective stars spin down with age.


title:
Theory of relativistic heat polynomials and one-sided L\'evy
  distributions

abstract:
  The theory of pseudo-differential operators is a powerful tool to deal with
differential equations involving differential operators under the square root
sign. These type of equations are pivotal elements to treat problems in
anomalous diffusion and in relativistic quantum mechanics. In this paper we
report on new and unsuspected links between fractional diffusion, quantum
relativistic equations and particular families of polynomials, linked to the
Carlitz family, and playing the role of relativistic heat polynomials. We
introduce generalizations of these polynomial families and point out their
specific use for the solutions of problems of practical importance.


title: A pressure tensor description for the time-resonant Weibel instability

abstract:
  We discuss a fluid model with inclusion of the complete pressure tensor
dynamics for the description of Weibel type instabilities in a counterstreaming
beams configuration. Differently from the case recently studied in Sarrat et
al. 2016, where perturbations perpendicular to the beams were considered, here
we focus only on modes propagating along the beams. Such a configuration is
responsible for the growth of two kind of instabilities, the Two-Stream
Instability and the Weibel instability, which in this geometry becomes
"time-resonant", i.e. propagative. This fluid description agrees with the
kinetic one and makes it possible e.g. to identify the transition between
non-propagative and propagative Weibel modes, already evidenced by Lazar et al.
2009 as a "slope-breaking" of the growth rate, in terms of a merger of two non
propagative Weibel modes.


title:
Distributed pursuit algorithms for probabilistic adversaries on
  connected graphs

abstract:
  A gambler moves between the vertices $1, \ldots, n$ of a graph using the
probability distribution $p_{1}, \ldots, p_{n}$. Multiple cops pursue the
gambler on the graph, only being able to move between adjacent vertices. We
investigate the expected capture time for the gambler against $k$ cops as a
function of $n$ and $k$ for three versions of the game: (1) known gambler: the
cops know the gambler's distribution (2) unknown gambler: the cops do not know
the gambler's distribution (3) known changing gambler: the gambler's
distribution can change every turn, but the cops know all of the gambler's
distributions from the beginning. We show for $n > k$ that if the cops are
allowed to choose their initial positions before the game starts and before
they know the gambler's distribution(s), and if both the gambler and the cops
play optimally, then the expected capture time is $\Theta(n/k)$ for the known
gambler, the unknown gambler, and the known changing gambler.


title: SLANTS: Sequential Adaptive Nonlinear Modeling of Vector Time Series

abstract:
  We propose a method for adaptive nonlinear sequential modeling of vector-time
series data. Data is modeled as a nonlinear function of past values corrupted
by noise, and the underlying non-linear function is assumed to be approximately
expandable in a spline basis. We cast the modeling of data as finding a good
fit representation in the linear span of multi-dimensional spline basis, and
use a variant of l1-penalty regularization in order to reduce the
dimensionality of representation. Using adaptive filtering techniques, we
design our online algorithm to automatically tune the underlying parameters
based on the minimization of the regularized sequential prediction error. We
demonstrate the generality and flexibility of the proposed approach on both
synthetic and real-world datasets. Moreover, we analytically investigate the
performance of our algorithm by obtaining both bounds of the prediction errors,
and consistency results for variable selection.


title:
A theoretical study of the build-up of the Sun's polar magnetic field by
  using a 3D kinematic dynamo model

abstract:
  We develop a three-dimensional kinematic self-sustaining model of the solar
dynamo in which the poloidal field generation is from tilted bipolar sunspot
pairs placed on the solar surface above regions of strong toroidal field by
using the SpotMaker algorithm, and then the transport of this poloidal field to
the tachocline is primarily caused by turbulent diffusion. We obtain a dipolar
solution within a certain range of parameters. We use this model to study the
build-up of the polar magnetic field and show that some insights obtained from
surface flux transport (SFT) models have to be revised. We present results
obtained by putting a single bipolar sunspot pair in a hemisphere and two
symmetrical sunspot pairs in two hemispheres.We find that the polar fields
produced by them disappear due to the upward advection of poloidal flux at low
latitudes, which emerges as oppositely-signed radial flux and which is then
advected poleward by the meridional flow. We also study the effect that a large
sunspot pair, violating Hale's polarity law would have on the polar field. We
find that there would be some effect---especially if the anti-Hale pair appears
at high latitudes in the mid-phase of the cycle---though the effect is not very
dramatic.


title: Dynamics in dimension zero. A survey

abstract:
  The goal of this paper is to put together several techniques in handling
dynamical systems on zero-dimensional spaces, such as array representation,
inverse limit representation, or Bratteli-Vershik representation. We describe
how one can switch from one representation to another. We also briefly review
some more recent related notions: symbolic extensions, symbolic extensions with
an embedding, and uniform generators. We devote a great deal of attention to
marker techniques and we use them to prove two types of results: one concerning
entropy and vertical data compression, and another, about the existence of
isomorphic minimal models for aperiodic systems. We also introduce so-called
decisiveness of Bratteli--Vershik systems and give for it a sufficient
condition.


title: Lying Your Way to Better Traffic Engineering

abstract:
  To optimize the flow of traffic in IP networks, operators do traffic
engineering (TE), i.e., tune routing-protocol parameters in response to traffic
demands. TE in IP networks typically involves configuring static link weights
and splitting traffic between the resulting shortest-paths via the
Equal-Cost-MultiPath (ECMP) mechanism. Unfortunately, ECMP is a notoriously
cumbersome and indirect means for optimizing traffic flow, often leading to
poor network performance. Also, obtaining accurate knowledge of traffic demands
as the input to TE is elusive, and traffic conditions can be highly variable,
further complicating TE. We leverage recently proposed schemes for increasing
ECMP's expressiveness via carefully disseminated bogus information ("lies") to
design COYOTE, a readily deployable TE scheme for robust and efficient network
utilization. COYOTE leverages new algorithmic ideas to configure (static)
traffic splitting ratios that are optimized with respect to all (even
adversarially chosen) traffic scenarios within the operator's "uncertainty
bounds". Our experimental analyses show that COYOTE significantly outperforms
today's prevalent TE schemes in a manner that is robust to traffic uncertainty
and variation. We discuss experiments with a prototype implementation of
COYOTE.


title:
ZFC proves that the class of ordinals is not weakly compact for
  definable classes

abstract:
  We prove that the class of all ordinals Ord is not weakly compact with
respect to definable classes. Specifically, in any model of ZFC, the definable
tree property fails for Ord, in that there is a definable Ord tree with no
definable cofinal branch; the definable partition property fails, in that there
is a definable 2-coloring of pairs from a certain definable proper class, with
no definable homogeneous proper class; and the definable compactness property
fails for $\mathcal{L}_{\infty,\omega}$, in that there is a definable theory in
this logic all of whose set-sized subtheories are satisfiable, but which has no
definable proper class model. In addition, we prove that the definable diamond
principle $\Diamond_{\rm Ord}$ holds if and only if there is a definable
well-ordering of the universe. And we prove that the common theory of all
spartan models of G\"odel-Bernays set theory, those having only definable
classes, is $\Pi^1_1$-complete.


title:
A generalization of the Gauss-Bonnet and Hopf-Poincar\'e theorems. Part
  II

abstract:
  This paper is a continuation of the paper F. A. Arias and M. Malakhaltsev "A
generalization of the Gauss-Bonnet and Hopf-Poincar\'e theorems",
ArXiv:1510.01395 [MathDG] 5 Oct 2015. Let $\pi : E \to M$ be a locally trivial
fiber bundle over a two-dimensional manifold $M$, and $\Sigma \subset M$ be a
discrete subset. A subset $Q \subset E$ is called an $n$-sheeted branched
section of the bundle $\pi$ if $Q' = \pi^{-1}(M \setminus \Sigma) \cap Q$ is a
$n$-sheeted covering of $M \setminus \Sigma$. The set $\Sigma$ is called the
singularity set of the branched section $Q$. We define the index of a
singularity point of a branched section, and give examples of its calculation,
in particular for branched sections of the projective tangent bundle of $M$
determined by binary differential equations. Also we define a resolution of
singularities of a branched section, and prove an analog of
Hopf-Poincar\'e-Gauss-Bonnet theorem for the branched sections admitting a
resolution.


title: Moduli spaces of framed sheaves and quiver varieties

abstract:
  In the first part of this paper we provide a survey of some fundamental
results about moduli spaces of framed sheaves on smooth projective surfaces. In
particular, we outline a result by Bruzzo and Markushevich, and discuss a few
significant examples. The moduli spaces of framed sheaves on $\mathbb{P}^2$, on
multiple blowup of $\mathbb{P}^2$ are described in terms of ADHM data and, when
this characterization is available, as quiver varieties. The second part is
devoted to a detailed study of framed sheaves on the Hirzebruch surface
$\Sigma_n$ in the case when the invariant expressing the necessary and
sufficient condition for the nonemptiness of moduli spaces attains its minimum
(what we call the "minimal case"). Our main result is that, under this
assumption, the corresponding moduli space is isomorphic to a Grassmannian
(when $n=1$), or to the direct sum of $n-1$ copies of the cotangent bundle of a
Grassmannian (when $n\geq 2$). Finally, by slightly generalizing a construction
due to Nakajima, we prove that these moduli spaces admit a description as
quiver varieties.


title:
Investigating the effects Diversity Mechanisms have on Evolutionary
  Algorithms in Dynamic Environments

abstract:
  Evolutionary algorithms have been successfully applied to a variety of
optimisation problems in stationary environments. However, many real world
optimisation problems are set in dynamic environments where the success
criteria shifts regularly. Population diversity affects algorithmic
performance, particularly on multiobjective and dynamic problems. Diversity
mechanisms are methods of altering evolutionary algorithms in a way that
promotes the maintenance of population diversity. This project intends to
measure and compare the performance effect a variety of diversity mechanisms
have on an evolutionary algorithm when facing an assortment of dynamic
problems.


title:
An improved dissipative coupling scheme for a system of Molecular
  Dynamics particles interacting with a Lattice Boltzmann fluid

abstract:
  We consider the dissipative coupling between a stochastic Lattice Boltzmann
(LB) fluid and a particle-based Molecular Dynamics (MD) system, as it was first
introduced by Ahlrichs and D\"unweg (J. Chem. Phys. 111 (1999) 8225). The fluid
velocity at the position of a particle is determined by interpolation, such
that a Stokes friction force gives rise to an exchange of momentum between the
particle and the surrounding fluid nodes. For efficiency reasons, the LB time
step is chosen as a multiple of the MD time step, such that the MD system is
updated more frequently than the LB fluid. In this situation, there are
different ways to implement the coupling: Either the fluid velocity at the
surrounding nodes is only updated every LB time step, or it is updated every MD
step. It is demonstrated that the latter choice, which enforces momentum
conservation on a significantly shorter time scale, is clearly superior in
terms of stability and accuracy, and nevertheless only marginally slower in
terms of execution speed. The second variant is therefore the recommended
implementation.


title: Non-trivial wandering domains for heterodimensional cycles

abstract:
  We present a sufficient condition for three-dimensional diffeomorphisms
having heterodimensional cycles to be approximated arbitrarily well by
diffeomorphisms with non-trivial contracting wandering domains via several
perturbations. The key idea is to show that diffeomorphisms with
heterodimensional cycles associated with saddle points with non-real
eigenvalues can be approximated by diffeomorphisms with generalized homoclinic
tangencies presented by Tatjer. The generalized homoclinic tangency is an
organizing center including a Bogdanov-Takens bifurcation, by which one can
obtain non-trivial contracting wandering domains together with a Denjoy-like
construction.


title:
Channel Estimation in Broadband Millimeter Wave MIMO Systems with
  Few-Bit ADCs

abstract:
  We develop a broadband channel estimation algorithm for millimeter wave
(mmWave) multiple input multiple output (MIMO) systems with few-bit
analog-to-digital converters (ADCs). Our methodology exploits the joint
sparsity of the mmWave MIMO channel in the angle and delay domains. We
formulate the estimation problem as a noisy quantized compressed-sensing
problem and solve it using efficient approximate message passing (AMP)
algorithms. In particular, we model the angle-delay coefficients using a
Bernoulli-Gaussian-mixture distribution with unknown parameters and use the
expectation-maximization (EM) forms of the generalized AMP (GAMP) and vector
AMP (VAMP) algorithms to simultaneously learn the distributional parameters and
compute approximately minimum mean-squared error (MSE) estimates of the channel
coefficients. We design a training sequence that allows fast, FFT-based
implementation of these algorithms while minimizing peak-to-average power ratio
at the transmitter, making our methods scale efficiently to large numbers of
antenna elements and delays. We present the results of a detailed simulation
study that compares our algorithms to several benchmarks. Our study
investigates the effect of SNR, training length, training type, ADC resolution,
and runtime on channel estimation MSE, mutual information, and achievable rate.
It shows that our methods allow one-bit ADCs to perform comparably to
infinite-bit ADCs at low SNR, and 4-bit ADCs to perform comparably to
infinite-bit ADCs at medium SNR.


title: Emergence of linguistic laws in human voice

abstract:
  Linguistic laws constitute one of the quantitative cornerstones of modern
cognitive sciences and have been routinely investigated in written corpora, or
in the equivalent transcription of oral corpora. This means that inferences of
statistical patterns of language in acoustics are biased by the arbitrary,
language-dependent segmentation of the signal, and virtually precludes the
possibility of making comparative studies between human voice and other animal
communication systems. Here we bridge this gap by proposing a method that
allows to measure such patterns in acoustic signals of arbitrary origin,
without needs to have access to the language corpus underneath. The method has
been applied to six different human languages, recovering successfully some
well-known laws of human communication at timescales even below the phoneme and
finding yet another link between complexity and criticality in a biological
system. These methods further pave the way for new comparative studies in
animal communication or the analysis of signals of unknown code.


title: Compact convex sets with prescribed facial dimensions

abstract:
  While faces of a polytope form a well structured lattice, in which faces of
each possible dimension are present, this is not true for general compact
convex sets. We address the question of what dimensional patterns are possible
for the faces of general closed convex sets. We show that for any finite
sequence of positive integers there exist compact convex sets which only have
extreme points and faces with dimensions from this prescribed sequence. We also
discuss another approach to dimensionality, considering the dimension of the
union of all faces of the same dimension. We show that the questions arising
from this approach are highly nontrivial and give examples of convex sets for
which the sets of extreme points have fractal dimension.


title: Best Subset Binary Prediction

abstract:
  We consider a variable selection problem for the prediction of binary
outcomes. We study the best subset selection procedure by which the covariates
are chosen by maximizing Manski (1975, 1985)'s maximum score objective function
subject to a constraint on the maximal number of selected variables. We show
that this procedure can be equivalently reformulated as solving a mixed integer
optimization problem, which enables computation of the exact or an approximate
solution with a definite approximation error bound. In terms of theoretical
results, we obtain non-asymptotic upper and lower risk bounds when the
dimension of potential covariates is possibly much larger than the sample size.
Our upper and lower risk bounds are minimax rate-optimal when the maximal
number of selected variables is fixed and does not increase with the sample
size. We illustrate usefulness of the best subset binary prediction approach
via Monte Carlo simulations and an empirical application of the work-trip
transportation mode choice.


title: Anomaly flows

abstract:
  The Anomaly flow is a flow which implements the Green-Schwarz anomaly
cancellation mechanism originating from superstring theory, while preserving
the conformally balanced condition of Hermitian metrics. There are several
versions of the flow, depending on whether the gauge field also varies, or is
assumed known. A distinctive feature of Anomaly flows is that, in $m$
dimensions, the flow of the Hermitian metric has to be inferred from the flow
of its $(m-1)$-th power $\omega^{m-1}$. We show how this can be done
explicitly, and we work out the corresponding flows for the torsion and the
curvature tensors. The results are applied to produce criteria for the
long-time existence of the flow, in the simplest case of zero slope parameter.


title: The Anomaly flow and the Fu-Yau equation

abstract:
  The Anomaly flow is shown to converge on toric fibrations with the Fu-Yau
ansatz, for both positive and negative values of the slope parameter $\alpha'$.
This implies both results of Fu and Yau on the existence of solutions for
Hull-Strominger systems, which they proved using different methods depending on
the sign of $\alpha'$. It is also the first case where the Anomaly flow can
even be shown to exist for all time. This is in itself remarkable from the
point of view of the theory of fully nonlinear partial differential equations,
as the elliptic terms in the flow are not concave.


title:
A study on nonnegativity preservation in finite element approximation of
  Nagumo-type nonlinear differential equations

abstract:
  Preservation of nonnengativity and boundedness in the finite element solution
of Nagumo-type equations with general anisotropic diffusion is studied. Linear
finite elements and the backward Euler scheme are used for the spatial and
temporal discretization, respectively. An explicit, an implicit, and two hybrid
explicit-implicit treatments for the nonlinear reaction term are considered.
Conditions for the mesh and the time step size are developed for the numerical
solution to preserve nonnegativity and boundedness. The effects of lumping of
the mass matrix and the reaction term are also discussed. The analysis shows
that the nonlinear reaction term has significant effects on the conditions for
both the mesh and the time step size. Numerical examples are given to
demonstrate the theoretical findings.


title: Portage: Bringing Hackers' Wisdom to Science

abstract:
  Providing users of HPC systems with a wide variety of up to date software
packages is a challenging task. Large software stacks built from source are
difficult to manage, requiring powerful package management tools. The Portage
package manager from Gentoo is a highly flexible tool that offers a mature
solution to this otherwise daunting task. The Gentoo Prefix project develops
and maintains a way of installing Gentoo systems in non-standard locations,
bringing the virtues of Gentoo to other operating systems. Here we demonstrate
how a Gentoo Prefix installation can be used to cross compile software packages
for the Intel Xeon Phi known as Knights Corner, as well as to manage large
software stacks in HPC environments.


title: CMB-S4 Science Book, First Edition

abstract:
  This book lays out the scientific goals to be addressed by the
next-generation ground-based cosmic microwave background experiment, CMB-S4,
envisioned to consist of dedicated telescopes at the South Pole, the high
Chilean Atacama plateau and possibly a northern hemisphere site, all equipped
with new superconducting cameras. CMB-S4 will dramatically advance cosmological
studies by crossing critical thresholds in the search for the B-mode
polarization signature of primordial gravitational waves, in the determination
of the number and masses of the neutrinos, in the search for evidence of new
light relics, in constraining the nature of dark energy, and in testing general
relativity on large scales.


title:
Identified particle production in pp collisions at $\sqrt{s}=$ 7 and 13
  TeV measured with ALICE

abstract:
  Proton-proton (pp) collisions have been used extensively as a reference for
the study of interactions of larger colliding systems at the LHC. Recent
measurements performed in high-multiplicity pp and proton-lead (p-Pb)
collisions have shown features that are reminiscent of those observed in
lead-lead (Pb-Pb) collisions. In this context, the study of identified particle
spectra and yields as a function of multiplicity is a key tool for the
understanding of similarities and differences between small and large systems.
We report on the production of pions, kaons, protons, $K^{0}_{\rm S}$,
$\Lambda$, $\Xi$, $\Omega$ and $K^{*0}$ as a function of multiplicity in pp
collisions at $\sqrt{s}=$ 7 TeV measured with the ALICE experiment. The work
presented here represents the most comprehensive set of results on identified
particle production in pp collisions at the LHC. Spectral shapes, studied both
for individual particles and via particle ratios as a function of $p_{\rm T}$,
exhibit an evolution with charged particle multiplicity that is similar to the
one observed in larger systems. In addition, results on the production of light
flavour hadrons in pp collisions at $\sqrt{s}=$ 13 TeV, the highest
centre-of-mass energy ever reached in the laboratory, are also presented and
compared with previous, lower energy results.


title: On spacetime structure and electrodynamics

abstract:
  Since almost all phenomena electrodynamics deal with have energy scales much
lower than the Higgs mass energy and intermediate boson energy, electrodynamics
of continuous media should be applicable and the constitutive relation of
spacetime/vacuum should be local and linear. What is the key characteristic of
the spacetime/vacuum? It is the Weak Equivalence Principle (WEP I) for
photons/wave packets of light which states that the spacetime trajectory of
light in a gravitational field depends only on its initial position and
direction of propagation, and does not depend on its frequency (energy) and
polarization, i.e. nonbirefringence of light propagation in spacetime/vacuum.
With this principle it is proved by the author in 1981 in the weak field limit,
and by Lammerzahl and Hehl in 2004 together with Favaro and Bergamin in 2011
without assuming the weak-field condition that the constitutive tensor must be
of the core metric form with only two additional degrees of freedom - the
pseudoscalar (Abelian axion or EM axion) degree of freedom and the scalar
(dilaton) degree of freedom (i.e. metric with axion and dilaton). In this
paper, we review this connection and the ultrahigh precision empirical tests of
nonbirefringence together with present status of tests of cosmic Abelian axion
and dilaton. If the stronger version of WEP is assumed, i.e. WEP II for photons
(wave packets of light) which states in addition to WEP I also that the
polarization state of the light would not change (e.g. no polarization rotation
for linear polarized light) and no amplification/attenuation of light, then no
Abelian (EM) axion and no dilaton, and we have a pure metric theory.


title: Accelerate Monte Carlo Simulations with Restricted Boltzmann Machines

abstract:
  Despite their exceptional flexibility and popularity, the Monte Carlo methods
often suffer from slow mixing times for challenging statistical physics
problems. We present a general strategy to overcome this difficulty by adopting
ideas and techniques from the machine learning community. We fit the
unnormalized probability of the physical model to a feedforward neural network
and reinterpret the architecture as a restricted Boltzmann machine. Then,
exploiting its feature detection ability, we utilize the restricted Boltzmann
machine for efficient Monte Carlo updates and to speed up the simulation of the
original physical system. We implement these ideas for the Falicov-Kimball
model and demonstrate improved acceptance ratio and autocorrelation time near
the phase transition point.


title:
Fits of Weak Annihilation and Hard Spectator Scattering Corrections in
  $B_{u,d}\to VV$ Decays

abstract:
  In this paper, the contributions of weak annihilation and hard spectator
scattering in $B\to \rho K^*$, $ K^* \bar{K}^*$, $\phi K^*$, $\rho\rho$ and
$\phi\phi$ decays are investigated within the framework of QCD factorization.
Using the experimental data available, we perform $\chi^2$ analyses of
end-point parameters in four cases based on the topology-dependent and
polarization-dependent parameterization schemes. The fitted results indicate
that: (i) In the topology-dependent scheme, the relation
$(\rho_A^{i},\phi_A^{i})\neq (\rho_A^{f},\phi_A^{f})$ gotten through $B\to PP$
and $PV$ decays is favored by the penguin-dominated $B\to VV$ decays at 95\% C.
L., (ii) The large hard spectator scattering corrections and/or the
simplification $ (\rho_H,\phi_H)= (\rho_A^{i},\phi_A^{i})$ are challenged by
${\cal B}(\bar{B}^0\to \rho^0 \rho^0)$, even though they are allowed by $B\to
PP$ and $PV$ decays and helpful for resolving "$\pi\pi$ puzzle", (iii) In the
polarization-dependent scheme, the relation $(\rho_A^{L},\phi_A^{L})\neq
(\rho_A^{T},\phi_A^{T})$ is always required. Moreover, we have updated the
theoretical results for $B\to VV$ decays with the best-fit values of end-point
parameters. A few observables, such as the ones of pure annihilation $B_d\to
\phi \phi$ decay, are also identified for probing the annihilation corrections.


title:
Mars sedimentary rock erosion rates constrained using crater counts,
  with applications to organic matter preservation and to the global dust cycle

abstract:
  Small-crater counts on Mars light-toned sedimentary rock are often
inconsistent with any isochron; these data are usually plotted then ignored. We
show (using an 18-HiRISE-image, >10^4 crater dataset) that these non-isochron
crater counts are often well-fit by a model where crater production is balanced
by crater obliteration via steady exhumation. For these regions, we fit erosion
rates. We infer that Mars light-toned sedimentary rocks typically erode at
~10^2 nm/yr, when averaged over 10 km^2 scales and 10^7-10^8 yr timescales.
Crater-based erosion-rate determination is consistent with independent
techniques, but can be applied to nearly all light-toned sedimentary rocks on
Mars. Erosion is swift enough that radiolysis cannot destroy complex organic
matter at some locations (e.g. paleolake deposits at SW Melas), but radiolysis
is a severe problem at other locations (e.g. Oxia Planum). The data suggest
that the relief of the Valles Marineris mounds is currently being reduced by
wind erosion, and that dust production on Mars <3 Gya greatly exceeds the
modern reservoir of mobile dust.


title: A Dynamic Window Neural Network for CCG Supertagging

abstract:
  Combinatory Category Grammar (CCG) supertagging is a task to assign lexical
categories to each word in a sentence. Almost all previous methods use fixed
context window sizes as input features. However, it is obvious that different
tags usually rely on different context window sizes. These motivate us to build
a supertagger with a dynamic window approach, which can be treated as an
attention mechanism on the local contexts. Applying dropout on the dynamic
filters can be seen as drop on words directly, which is superior to the regular
dropout on word embeddings. We use this approach to demonstrate the
state-of-the-art CCG supertagging performance on the standard test set.


title: Monodromy of Fermat Surfaces and Modular Symbols for Fermat curves

abstract:
  Let $F_n$ denote the Fermat curve given by $x^n+y^n=z^n$ and let $\mu_n$
denote the Galois module of $n$th roots of unity. It is known that the integral
homology group $H_1(F_n,\Z)$ is a cyclic $\Z[\mu_n\times \mu_n]$ module. In
this paper, we prove this result using modular symbols and the modular
description of Fermat curves; moreover we find a basis for the integral
homology group $H_1(F_n,\Z)$. We also construct a family of Fermat curves using
the Fermat surface and compute its monodromy.


title:
A New Theoretical and Technological System of Imprecise-Information
  Processing

abstract:
  Imprecise-information processing will play an indispensable role in
intelligent systems, especially in the anthropomorphic intelligent systems (as
intelligent robots). A new theoretical and technological system of
imprecise-information processing has been founded in Principles of
Imprecise-Information Processing: A New Theoretical and Technological System[1]
which is different from fuzzy technology. The system has clear hierarchy and
rigorous structure, which results from the formation principle of imprecise
information and has solid mathematical and logical bases, and which has many
advantages beyond fuzzy technology. The system provides a technological
platform for relevant applications and lays a theoretical foundation for
further research.


title: Cyclic completion of the anamorphic universe

abstract:
  Cyclic models of the universe have the advantage of avoiding initial
conditions problems related to postulating any sort of beginning in time. To
date, the only known viable examples of cyclic models have been ekpyrotic. In
this paper, we show that the recently proposed anamorphic scenario can also be
made cyclic. The key to the cyclic completion is a classically stable,
non-singular bounce. Remarkably, even though the bounce construction was
originally developed to connect a period of contraction with a period of
expansion both described by Einstein gravity, we show here that it can
naturally be modified to connect an ordinary contracting phase described by
Einstein gravity with a phase of anamorphic smoothing. The paper will present
the basic principles and steps in constructing cyclic anamorphic models.


title:
Local M-estimation with Discontinuous Criterion for Dependent and
  Limited Observations

abstract:
  This paper examines asymptotic properties of local M-estimators under three
sets of high-level conditions. These conditions are sufficiently general to
cover the minimum volume predictive region, conditional maximum score estimator
for a panel data discrete choice model, and many other widely used estimators
in statistics and econometrics. Specifically, they allow for discontinuous
criterion functions of weakly dependent observations, which may be localized by
kernel smoothing and contain nuisance parameters whose dimension may grow to
infinity. Furthermore, the localization can occur around parameter values
rather than around a fixed point and the observation may take limited values,
which leads to set estimators. Our theory produces three different
nonparametric cube root rates and enables valid inference for the local
M-estimators, building on novel maximal inequalities for weakly dependent data.
Our results include the standard cube root asymptotics as a special case. To
illustrate the usefulness of our results, we verify our conditions for various
examples such as the Hough transform estimator with diminishing bandwidth,
maximum score-type set estimator, and many others.


title:
Full dimensional sets of reals whose sums of partial quotients increase
  in certain speed

abstract:
  For a real $x\in(0,1)\setminus\mathbb{Q}$, let $x=[a_1(x),a_2(x),\cdots]$ be
its continued fraction expansion. Let $s_n(x)=\sum_{j=1}^n a_j(x)$. The
Hausdorff dimensions of the level sets $E_{\varphi(n),\alpha}:=\{x\in(0,1):
\lim_{n\rightarrow\infty}\frac{s_n(x)}{\varphi(n)}=\alpha\}$ for $\alpha\geq 0$
and a non-decreasing sequence $\{\varphi(n)\}_{n=1}^\infty$ have been studied
by E. Cesaratto, B. Vall\'ee, J. Wu, J. Xu, G. Iommi, T. Jordan, L. Liao, M.
Rams \emph{et al}. In this work we carry out a kind of inverse project of their
work, that is, we consider the conditions on $\varphi(n)$ under which one can
expect a $1$-dimensional set $E_{\varphi(n),\alpha}$. We give certain upper and
lower bounds on the increasing speed of $\varphi(n)$ when
$E_{\varphi(n),\alpha}$ is of Hausdorff dimension 1 and a new class of
sequences $\{\varphi(n)\}_{n=1}^\infty$ such that $E_{\varphi(n),\alpha}$ is of
full dimension. There is also a discussion of the problem in the irregular
case.


title:
Experimentally freezing quantum discord in a dissipative environment
  using dynamical decoupling

abstract:
  The discovery of the intriguing phenomenon that certain kinds of quantum
correlations remain impervious to noise up to a specific point in time and then
suddenly decay, has generated immense recent interest. We exploit dynamical
decoupling sequences to prolong the persistence of time-invariant quantum
discord in a system of two NMR qubits decohering in independent dephasing
environments. We experimentally prepare two-qubit Bell-diagonal quantum states
that interact with individual dephasing channels and demonstrate the effect of
dynamical decoupling on the preservation of both quantum and classical
correlations. We are able to freeze quantum discord over long time scales in
the presence of noise, using dynamical decoupling. We use robust
state-independent dynamical decoupling schemes for state preservation and
demonstrate that these schemes are able to successfully preserve quantum
discord.


title:
Nonequilibrium steady state of biochemical cycle kinetics under
  non-isothermal conditions

abstract:
  Nonequilibrium steady state of isothermal biochemical cycle kinetics has been
extensively studied, but much less investigated under non-isothermal
conditions. However, once the heat exchange between subsystems is rather slow,
the isothermal assumption of the whole system meets great challenge, which is
indeed the case inside many kinds of living organisms. Here we generalize the
nonequilibrium steady-state theory of isothermal biochemical cycle kinetics, in
the master-equation models, to the situation in which the temperatures of
subsystems can be far from uniform. We first obtain a new thermodynamic
relation between the chemical reaction rates and thermodynamic potentials under
such a non-isothermal circumstances, which immediately implies simply applying
the isothermal transition-state rate formula for each chemical reaction in
terms of only the reactants' temperature, is not thermodynamically consistent.
Therefore, we mathematically derive several revised reaction-rate formulas
which not only obey the new thermodynamic relation but also approximate the
exact reaction rate better than the rate formula under isothermal condition.
The new thermodynamic relation also predicts that in the transporter system
with different temperatures inside and outside the membrane, the net flux of
the transported molecules can possibly even go against the temperature gradient
in the absence of the chemical driving force.


title: Dataiku's Solution to SPHERE's Activity Recognition Challenge

abstract:
  Our team won the second prize of the Safe Aging with SPHERE Challenge
organized by SPHERE, in conjunction with ECML-PKDD and Driven Data. The goal of
the competition was to recognize activities performed by humans, using sensor
data. This paper presents our solution. It is based on a rich pre-processing
and state of the art machine learning methods. From the raw train data, we
generate a synthetic train set with the same statistical characteristics as the
test set. We then perform feature engineering. The machine learning modeling
part is based on stacking weak learners through a grid searched XGBoost
algorithm. Finally, we use post-processing to smooth our predictions over time.


title:
Stochastic Alternating Direction Method of Multipliers with Variance
  Reduction for Nonconvex Optimization

abstract:
  In the paper, we study the stochastic alternating direction method of
multipliers (ADMM) for the nonconvex optimizations, and propose three classes
of the nonconvex stochastic ADMM with variance reduction, based on different
reduced variance stochastic gradients. Specifically, the first class called the
nonconvex stochastic variance reduced gradient ADMM (SVRG-ADMM), uses a
multi-stage scheme to progressively reduce the variance of stochastic
gradients. The second is the nonconvex stochastic average gradient ADMM
(SAG-ADMM), which additionally uses the old gradients estimated in the previous
iteration. The third called SAGA-ADMM is an extension of the SAG-ADMM method.
Moreover, under some mild conditions, we establish the iteration complexity
bound of $O(1/\epsilon)$ of the proposed methods to obtain an
$\epsilon$-stationary solution of the nonconvex optimizations. In particular,
we provide a general framework to analyze the iteration complexity of these
nonconvex stochastic ADMM methods with variance reduction. Finally, some
numerical experiments demonstrate the effectiveness of our methods.


title:
Driving field amplitude gauged quantitative inverse spin Hall effect
  detection

abstract:
  Spin transport in thin-film materials can be studied by ferromagnetic
resonantly (FMR) driven spin pumping of a charge-free spin current which
induces an electromotive force through the inverse spin Hall effect (ISHE). For
quantitative ISHE experiments, precise control of the FMR driving field
amplitude $B_1$ is crucial. This study exploits in situ monitoring of $B_1$ by
utilization of electron paramagnetic resonantly (EPR) induced transient
nutation of paramagnetic molecules (a 1:1 complex of
{\alpha},{\gamma}-bisdiphenylene-{\beta}-phenylallyl and benzene, BDPA) placed
as $B_1$ probe in proximity of a NiFe/Pt-based ISHE device. Concurrent to an
ISHE experiment, $B_1$ is obtained from the inductively measured BDPA
Rabi-nutation frequency. Higher reproducibility is achieved by renormalization
of the ISHE voltage to $B_1^2$ with an accuracy that is determined by the
homogeneity of the FMR driving field and thus by the applied microwave
resonator and ISHE device setup.


title:
Image Segmentation Based on the Self-Balancing Mechanism in Virtual 3D
  Elastic Mesh

abstract:
  In this paper, a novel model of 3D elastic mesh is presented for image
segmentation. The model is inspired by stress and strain in physical elastic
objects, while the repulsive force and elastic force in the model are defined
slightly different from the physical force to suit the segmentation problem
well. The self-balancing mechanism in the model guarantees the stability of the
method in segmentation. The shape of the elastic mesh at balance state is used
for region segmentation, in which the sign distribution of the points'z
coordinate values is taken as the basis for segmentation. The effectiveness of
the proposed method is proved by analysis and experimental results for both
test images and real world images.


title:
Robust force sensing for a free particle in a dissipative optomechanical
  system with a parametric amplifier

abstract:
  We theoretically investigate optical detection of a weak classical force
acting on a free particle in a dissipative coupling optomechanical system with
a degenerate parametric amplifier (PA). We show that the PA allows one to
achieve the force sensitivity far better than the standard quantum limit (SQL)
over a broad range of the detection frequencies. The improvement depends on the
parametric gain and the driving power. Moreover, we discuss the effects of the
mechanical damping and the thermal noise on the force sensitivity. We find that
the robustness of the force sensitivity much better than the SQL against the
mechanical damping and the thermal noise is achievable in the presence of the
PA with a high parametric gain. For the temperature $T = 1$ K, the improvement
in sensitivity is better by a factor of about 7 when the driving power is set
at a value corresponding to the SQL with no PA.


title:
Matching of Images with Rotation Transformation Based on the Virtual
  Electromagnetic Interaction

abstract:
  A novel approach of image matching for rotating transformation is presented
and studied. The approach is inspired by electromagnetic interaction force
between physical currents. The virtual current in images is proposed based on
the significant edge lines extracted as the fundamental structural feature of
images. The virtual electromagnetic force and the corresponding moment is
studied between two images after the extraction of the virtual currents in the
images. Then image matching for rotating transformation is implemented by
exploiting the interaction between the virtual currents in the two images to be
matched. The experimental results prove the effectiveness of the novel idea,
which indicates the promising application of the proposed method in image
registration.


title: Conic James' Compactness Theorem

abstract:
  Our main result is the following: {\it Let $E$ be a Banach space and $D$ be a
weakly compact subset of $E$ with $0\notin D$. If $A$ is a bounded subset of
$E$ such that every $x^*\in E^*$ with $x^*(D) >0$ attains its supremum on $A$,
then $A$ is weakly relatively compact.}


title:
Controllable deposition of titanium dioxides onto carbon nanotubes in
  aqueous solutions

abstract:
  Within the field of nanotechnology, nano-scale composites have significant
potential in the development of advanced materials for functional applications.
Here, composites based on carbon nanotubes and titanium dioxides have been
prepared with titanyl sulfate using a chemical bath deposition method at or
near room temperature. Two kinds of titanium dioxide depositions corresponding
to rutile and anatase were sheathed on carbon nanotubes evenly by adjusting the
precursor concentration and temperature. Possible composite mechanisms are
discussed. Compared with original tubes, the specific surface areas have been
improved nearly four times and the content ratio of mesostructures has also
been increased after deposition processes.


title:
Vehicle-to-Vehicle Communications with Urban Intersection Path Loss
  Models

abstract:
  Vehicle-to-vehicle (V2V) communication can improve road safety and traffic
efficiency, particularly around critical areas such as intersections. We
analytically derive V2V success probability near an urban intersection, based
on empirically supported line-of-sight (LOS), weak-line-of-sight (WLOS), and
non-line-of-sight (NLOS) channel models. The analysis can serve as a
preliminary design tool for performance assessment over different system
parameters and target performance requirements.


title:
Liouville first passage percolation: geodesic length exponent is
  strictly larger than 1 at high temperatures

abstract:
  Let $\{\eta(v): v\in V_N\}$ be a discrete Gaussian free field in a
two-dimensional box $V_N$ of side length $N$ with Dirichlet boundary
conditions. We study the Liouville first passage percolation, i.e., the
shortest path metric where each vertex is given a weight of $e^{\gamma
\eta(v)}$ for some $\gamma>0$. We show that for sufficiently small but fixed
$\gamma>0$, with probability tending to $1$ as $N\to \infty$, all geodesics
between vertices of macroscopic Euclidean distances simultaneously have (the
conjecturally unique) length exponent strictly larger than 1.


title: Origin of magnetic anisotropy in doped Ce$_2$Co$_{17}$ alloys

abstract:
  Magnetocrystalline anisotropy (MCA) in doped Ce$_{2}$Co$_{17}$ and other
competing structures was investigated using density functional theory. We
confirmed that the MCA contribution from dumbbell Co sites is very negative.
Replacing Co dumbbell atoms with a pair of Fe or Mn atoms greatly enhance the
uniaxial anisotropy, which agrees quantitatively with experiment, and this
enhancement arises from electronic-structure features near the Fermi level,
mostly associated with dumbbell sites. With Co dumbbell atoms replaced by other
elements, the variation of anisotropy is generally a collective effect and
contributions from other sublattices may change significantly. Moreover, we
found that Zr doping promotes the formation of 1-5 structure that exhibits a
large uniaxial anisotropy, such that Zr is the most effective element to
enhance MCA in this system.


title:
Trajectory Prediction of Rotating Objects in Viscous Fluid: Based on
  Kinematic Investigation of Magnus Glider

abstract:
  The case of a rotating object traveling through viscous fluid appears in many
phenomena like the banana ball and missile movement. In this work, we build a
model to predict the trajectory of such rotating objects with near-cylinder
geometry. The analytical expression of Magnus force is given and a wind tunnel
experiment is carried out, which shows the Magnus force is well proportional to
the product of angular velocity and centroid velocity. The trajectory
prediction is consistent with the trajectory record experiment of Magnus
glider, which implies the validity and robustness of this model.


title: Inverse Diffusion Curves using Shape Optimization

abstract:
  The inverse diffusion curve problem focuses on automatic creation of
diffusion curve images that resemble user provided color fields. This problem
is challenging since the 1D curves have a nonlinear and global impact on
resulting color fields via a partial differential equation (PDE). We introduce
a new approach complementary to previous methods by optimizing curve geometry.
In particular, we propose a novel iterative algorithm based on the theory of
shape derivatives. The resulting diffusion curves are clean and well-shaped,
and the final image closely approximates the input. Our method provides a
user-controlled parameter to regularize curve complexity, and generalizes to
handle input color fields represented in a variety of formats.


title: Reconstruction of colourings without freezing

abstract:
  We prove that reconstruction in the $k$-colouring model occurs strictly below
the threshold for freezing for large $k$.


title: An introduction to Ulrich bundles

abstract:
  After recalling the definition and basic properties of Ulrich bundles, we
focus on the existence problem: does any smooth projective variety carry a
Ulrich bundle? We show that the Serre construction provides a positive answer
on certain surfaces and threefolds.


title: Probing the magnetic fields in L1415 and L1389

abstract:
  We present the R-band polarimetric results towards two nebulae L1415 and
L1389 containing low luminosity stars. Aim of this study is to understand the
role played by magnetic fields in formation of low luminosity objects. Linear
polarization arise due to dichroism of the background starlight projected on
the cloud providing the plane-of-the sky magnetic field orientation. The
offsets between mean magnetic field directions obtained towards L1415 and L1389
and the projected outflow axes are found to be 35$^{\circ}$ and 12$^{\circ}$,
respectively. The offset between cloud minor axes and mean envelope magnetic
field direction in L1415 and L1389 are 50$^{\circ}$ and 87$^{\circ}$,
respectively. To estimate the magnetic field strength by using the updated
Chandrasekhar-Fermi relation, we obtained the $^{12}$CO(J=1-0) line velocity
dispersion value towards L1415 cloud using the TRAO single dish observations.
The values of B$_{pos}$ in L1415 and L1389 are found to be 28$~\mu$G and
149$~\mu$G using CF technique and 23$~\mu$G and 140$~\mu$G using structure
function analysis, respectively. The values of B$_{pos}$ in these clouds are
found to be consistent using both the techniques. By combining the present
results with those obtained from our previous study of magnetic fields in cores
with VeLLOs, we attempt to improve the sample of cores with low luminosity
protostars and bridge the gap between the understanding of importance of
magnetic fields in cores with VeLLOs and low luminosity protostars. The Results
of this work and that of our previous work show that the outflow directions are
aligned with envelope magnetic fields of the clouds.


title:
The SAMI Galaxy Survey: Asymmetry in Gas Kinematics and its links to
  Stellar Mass and Star Formation

abstract:
  We study the properties of kinematically disturbed galaxies in the SAMI
Galaxy Survey using a quantitative criterion, based on kinemetry (Krajnovic et
al.). The approach, similar to the application of kinemetry by Shapiro et al.
uses ionised gas kinematics, probed by H{\alpha} emission. By this method
23+/-7% of our 360-galaxy sub-sample of the SAMI Galaxy Survey are
kinematically asymmetric. Visual classifications agree with our kinemetric
results for 90% of asymmetric and 95% of normal galaxies. We find stellar mass
and kinematic asymmetry are inversely correlated and that kinematic asymmetry
is both more frequent and stronger in low-mass galaxies. This builds on
previous studies that found high fractions of kinematic asymmetry in low mass
galaxies using a variety of different methods. Concentration of star forma-
tion and kinematic disturbance are found to be correlated, confirming results
found in previous work. This effect is stronger for high mass galaxies (log(M*)
> 10) and indicates that kinematic disturbance is linked to centrally
concentrated star formation. Comparison of the inner (within 0.5Re) and outer
H{\alpha} equivalent widths of asymmetric and normal galaxies shows a small but
significant increase in inner equivalent width for asymmetric galaxies.


title: Prime powers in sums of terms of binary recurrence sequences

abstract:
  Let $\{u_{n}\}_{n \geq 0}$ be a non-degenerate binary recurrence sequence
with positive, square-free discriminant and $p$ be a fixed prime number. In
this paper, we have shown the finiteness result for the solutions of the
Diophantine equation $u_{n_{1}} + u_{n_{2}} + \cdots + u_{n_{t}} = p^{z}$ with
some conditions on $n_i $ for all $1\leq i \leq t$. Moreover, we explicitly
find all the powers of three which are sums of three balancing numbers using
the lower bounds for linear forms in logarithms. Further, we use a variant of
Baker-Davenport reduction method in Diophantine approximation due to Dujella
and Peth\H{o}.


title: The Halos and Environments of Nearby Galaxies (HERON) Survey

abstract:
  We have used dedicated 0.7m telescopes in California and Israel to image the
halos of ~200 galaxies in the Local Volume to 29 mag/sq arcsec, the sample
mainly drawn from the 2MASS Large Galaxy Atlas (LGA). We supplement the LGA
sample with dwarf galaxies and more distant giant ellipticals. Low surface
brightness halos exceeding 50 kpc in diameter are found only in galaxies more
luminous than L* and classic interaction signatures are relatively infrequent.
Halo diameter is correlated with total galaxy luminosity. Extended low surface
brightness halos are present even in galaxies as faint as M_V=-18. Edge-on
galaxies with boxy bulges tend to lack extended spheroidal halos, while those
with large classical bulges exhibit extended round halos, supporting the
notions that boxy or barlike bulges originate from disks. Most face-on spiral
galaxies present features that appear to be irregular extensions of spiral
arms, although rare cases show smooth boundaries with no sign of star
formation. Although we serendipitously discovered a dwarf galaxy undergoing
tidal disruption in the halo of NGC 4449, we found no comparable examples in
our general survey. A search for similar examples in the Local Volume
identified hcc087, a tidally disrupting dwarf galaxy in the Hercules Cluster,
but we do not confirm an anomalously large half-light radius reported for the
dwarf VCC 1661.


title:
Otto refrigerator based on a superconducting qubit: classical and
  quantum performance

abstract:
  We analyse a quantum Otto refrigerator based on a superconducting qubit
coupled to two LC-resonators each including a resistor acting as a reservoir.
We find various operation regimes: nearly adiabatic (low driving frequency),
ideal Otto cycle (intermediate frequency), and non-adiabatic coherent regime
(high frequency). In the nearly adiabatic regime, the cooling power is
quadratic in frequency, and we find substantially enhanced coefficient of
performance $\epsilon$, as compared to that of an ideal Otto cycle. Quantum
coherent effects lead invariably to decrease in both cooling power and
$\epsilon$ as compared to purely classical dynamics. In the non-adiabatic
regime we observe strong coherent oscillations of the cooling power as a
function of frequency. We investigate various driving waveforms: compared to
the standard sinusoidal drive, truncated trapezoidal drive with optimized rise
and dwell times yields higher cooling power and efficiency.


title:
LHC production of forward-center and forward-forward di-jets in the
  $k_t$-factorization $unintegrated$ parton distribution frameworks

abstract:
  The present work is devoted to study the high-energy $QCD$ events, such as
the di-jet productions from proton-proton inelastic collisions at the $LHC$ in
the forward-center and the forward-forward configurations, using the
$unintegrated$ parton distribution functions ($UPDF$) in the
$k_t$-factorization framework. The $UPDF$ of $Kimber$ et. al. ($KMR$) and
$Martin$ et.al. ($MRW$) are generated in the leading order ($LO$) and
next-to-leading order ($NLO$), using the $Harland-Lang$ et al. ($MMHT2014$)
$PDF$ libraries. While working in the forward-center and the forward-forward
rapidity sectors, one can probe the parton densities at very low longitudinal
momentum fractions ($x$). Therefore, such a computation can provide a valuable
test-field for these $UPDF$. We find very good agreement with the corresponding
di-jet production data available from $LHC$ experiments. On the other hand, as
we have also stated in our previous works, (i.e. the protons longitudinal and
transverse structure function as well as hadron-hadron $LHC$ $W/Z$ production),
the present calculations based on the $KMR$ prescriptions show a better
agreement with the corresponding experimental data. This conclusion is
achieved, due to the particular visualization of the angular ordering
constraint ($AOC$), despite the fact that the $LO-MRW$ and the $NLO-MRW$
formalisms both employ better theoretical descriptions of the
$Dokshitzer$-$Gribov$-$Lipatov$ -$Altarelli$-$Parisi$ ($DGLAP$) evolution
equation, and hence are expected to produce better results. The form of the
$AOC$ in the $KMR$ prescription automatically includes the re-summation of the
higher-order $ln({1/x})$ type contributions, i.e. the
$Balitski$-$Fadin$-$Kuraev$-$Lipatov$ ($BFKL$) logarithms, in the $LO$-$DGLAP$
evolution equation.


title:
Integration by Parts formula for SPDEs with Multiplicative Noise and its
  Applications

abstract:
  By using the Malliavin calculus, the Driver-type integration by parts formula
is established for the semigroup associated to to SPDEs with Multiplicative
Noise. Moreover, estimates on the density of heat kernel w.r.t. Lebesgue
measure are obtained in finite dimension case.


title:
Atomic size zone interaction potential between two ground-state cold
  atoms

abstract:
  The complex-source-point model are already used in the exact solution for the
urtrashort pulse and nonparaxial beam. In this letter we have used the
complex-source-point model to deduce the interaction potential equation for the
separation R between two atoms which is comparable with the size of the atoms.
We show the result and the characteristics of the numerical calculation. Since
the singular point around R=0 is removed by using the complex-source-point
model, so that we can obtain the result force around R=0. With the decreasing
of the distance between two atoms, the force switches from the electromagnetic
force to the strong force by use our equation.


title:
Reconstructing sparse exponential polynomials from samples: Stirling
  numbers and Hermite interpolation

abstract:
  Prony's method, in its various concrete algorithmic realizations, is
concerned with the reconstruction of a sparse exponential sum from integer
samples. In several variables, the reconstruction is based on finding the
variety for a zero dimensional radical ideal. If one replaces the coefficients
in the representation by polynomials, i.e., tries to recover sparse exponential
polynomials, the zeros associated to the ideal have multiplicities attached to
them . The precise relationship between the coefficients in the exponential
polynomial and the multiplicity spaces are pointed out in this paper.


title:
The Role of Information in System Stability with Partially Observable
  Servers

abstract:
  We consider a simple discrete-time controlled queueing system, where the
controller has a choice of which server to use at each time slot and server
performance varies according to a Markov modulated random environment. We
explore the role of information in the system stability region. At the extreme
cases of information availability, that is when there is either full
information or no information, stability regions and maximally stabilizing
policies are trivial. But in the more realistic cases where only the
environment state of the selected server is observed, only the service
successes are observed or only queue length is observed, finding throughput
maximizing control laws is a challenge. To handle these situations, we devise a
Partially Observable Markov Decision Process (POMDP) formulation of the problem
and illustrate properties of its solution. We further model the system under
given decision rules, using Quasi-Birth-and-Death (QBD) structure to find a
matrix analytic expression for the stability bound. We use this formulation to
illustrate how the stability region grows as the number of controller belief
states increases.
  Our focus in this paper is on the simple case of two servers where the
environment of each is modulated according to a two-state Markov chain. As
simple as this case seems, there appear to be no closed form descriptions of
the stability region under the various regimes considered. Our numerical
approximations to the POMDP Bellman equations and the numerical solutions of
the QBDs hint at a variety of structural results.


title:
Specialization map between stratified bundles and pro-\'etale
  fundamental group

abstract:
  Given a projective family of semi-stable curves over a complete discrete
valuation ring of characteristic p with algebraically closed residue field, we
construct a specialization functor between the category of continuous
representations of the pro-\'etale fundamental group of the closed fibre and
the category of stratified bundles on the geometric generic fibre. By Tannakian
duality, this functor induces a morphism between the corresponding affine group
schemes. We show that this morphism is a lifting of the specialization map,
constructed by Grothendieck, between the \'etale fundamental groups.


title:
White matter biomarkers from fast protocols using axially symmetric
  diffusion kurtosis imaging

abstract:
  White matter tract integrity (WMTI) can characterize brain microstructure in
areas with highly aligned fiber bundles. Several WMTI biomarkers have now been
validated against microscopy and provided promising results in studies of brain
development and aging, and in a number of brain disorders. Currently, WMTI is
mostly used in dedicated animal studies and clinical studies of slowly
progressing diseases but has not yet emerged as a routine clinical tool. To
this end, a less data intensive experimental method would be beneficial by
enabling high resolution validation studies, and ease clinical applications by
speeding up data acquisition compared to typical diffusion kurtosis imaging
(DKI) protocols utilized as part of WMTI imaging. Here, we evaluate WMTI based
on recently introduced axially symmetric DKI which has lower data demand than
conventional DKI. We compare WMTI parameters derived from conventional DKI to
those calculated analytically from axially symmetric DKI. We employ numerical
simulations, as well as data from fixed rat spinal cord (1) and in vivo human
(3) and rat brain (4). Our analysis shows that analytical WMTI based on axially
symmetric DKI with sparse data sets (19 images) produces WMTI metrics that
correlate strongly with estimates based on traditional DKI data sets (60 images
or more). We demonstrate the preclinical potential of the proposed WMTI
technique in in vivo rat brain (300 {\mu}m isotropic resolution with whole
brain coverage). WMTI parameter estimates are subject to a duality leading to
two solution branches dependent on a sign choice which is currently debated.
Results from both of these branches are presented and discussed throughout our
analysis. The proposed fast WMTI approach may be useful for preclinical
research and e.g. clinical evaluation of patients with traumatic white matter
injuries or symptoms of neurovascular or neuroinflammatory disorders.


title: Modelling quantum black hole

abstract:
  Novel bound states are obtained for manifolds with singular potentials. These
singular potentials require proper boundary conditions across boundaries. The
number of bound states match nicely with what we would expect for black holes.
Also they serve to model membrane mechanism for the black hole horizons in
simpler contexts. The singular potentials can also mimic expanding boundaries
elegantly, there by obtaining appropriately tuned radiation rates.


title: Reconstructing the Star Knowledge of Aboriginal Tasmanians

abstract:
  The canopy of stars is a central presence in the daily and spiritual lives of
Aboriginal Tasmanians. With the arrival of European colonists, Tasmanian
astronomical knowledge and traditions were interrupted and dispersed. Fragments
can be found scattered in the ethnographic and historical record throughout the
nineteenth century. We draw from ethnohistorical documents to analyse and
reconstruct Aboriginal astronomical knowledge in Tasmania. This analysis
demonstrates that stars, the Milky Way, constellations, dark nebula, the Sun,
Moon, meteors, and aurorae held cultural, spiritual, and subsistence
significance within the Aboriginal cultures of Tasmania. We move beyond a
monolithic view of Aboriginal astronomical knowledge in Tasmania, commonly
portrayed in previous research, to lay the groundwork for future ethnographic
and archaeological fieldwork with Aboriginal elders and communities.


title: Degenerate $C$-distribution semigroups in locally convex spaces

abstract:
  The main purpose of this paper is to investigate degenerate $C$-distribution
semigroups in the setting of barreled sequentially complete locally convex
spaces. In our approach, the infinitesimal generator of a degenerate
$C$-distribution semigroup is a multivalued linear operator and the
regularizing operator $C$ is not necessarily injective. We provide a few
important theoretical novelties, considering also exponential subclasses of
degenerate $C$-distribution semigroups.