title: A k-core Decomposition Framework for Graph Clustering

abstract:
  Graph clustering or community detection constitutes an important task for
investigating the internal structure of graphs, with a plethora of applications
in several domains. Traditional techniques for graph clustering, such as
spectral methods, typically suffer from high time and space complexity. In this
article, we present CoreCluster, an efficient graph clustering framework based
on the concept of graph degeneracy, that can be used along with any known graph
clustering algorithm. Our approach capitalizes on processing the graph in an
hierarchical manner provided by its core expansion sequence, an ordered
partition of the graph into different levels according to the k-core
decomposition. Such a partition provides an efficient way to process the graph
in an incremental manner that preserves its clustering structure, while making
the execution of the chosen clustering algorithm much faster due to the smaller
size of the graph's partitions onto which the algorithm operates. An
experimental analysis on a multitude of real and synthetic data demonstrates
that our approach can be applied to any clustering algorithm accelerating the
clustering process, while the quality of the clustering structure is preserved
or even improved.


title:
Structural and electronic properties of ultrathin FeSe films grown on
  Bi$_2$Se$_3$(0001) studied by STM/STS

abstract:
  We report scanning tunnelling microscopy and spectroscopy (STM/STS) studies
on one and two unit cell (UC) high FeSe thin films grown on Bi$_2$Se$_3$(0001).
In our thin films, we find the tetragonal phase of FeSe and dumb-bell shaped
defects oriented along Se-Se bond directions. In addition, we observe striped
moir\'e patterns with a periodicity of ($7.3\pm 0.1$) nm generated by the
mismatch between the FeSe lattice and the Bi$_2$Se$_3$ lattice. We could not
find any signature of a superconducting gap in the tunneling spectra measured
on the surface of one and two UC thick islands of FeSe down to 6.5 K. The
spectra rather show an asymmetric behavior across and a finite density of
states at the Fermi level ($E_F$) resembling those taken in the normal state of
bulk FeSe.


title: Univalence and quasiconformal extension of an integral operator

abstract:
  In this paper we give some sufficient conditions of analyticity and
univalence for functions defined by an integral operator. Next, we refine the
result to a quasiconformal extension criterion with the help of the Becker's
method. Further, new univalence criteria and the significant relationships with
other results are given. A number of known univalence conditions would follow
upon specializing the parameters involved in our main results.


title:
Changes in extensive air showers from isotropic Lorentz violation in the
  photon sector

abstract:
  We consider a theory with isotropic nonbirefringent Lorentz violation in the
photon sector and explore the effects on the development of the electromagnetic
component of extensive air showers in the Earth atmosphere. Specifically, we
consider the case of a "fast" photon with a phase velocity larger than the
maximum attainable velocity of a massive Dirac fermion (this case corresponds
to a negative Lorentz-violating parameter $\kappa$ in the action). Shower
photons with above-threshold energies decay promptly into electron-positron
pairs, instead of decaying by the conventional production of electron-positron
pairs in the background fields of atomic nuclei. This rapid production of
charged leptons accelerates the shower development, decreasing the atmospheric
depth of the shower maximum ($X_\text{max}$) by an amount which could be
measured by cosmic-ray observatories. Precise measurements of $X_\text{max}$
could then improve existing limits on the negative Lorentz-violating parameter
$\kappa$ by several orders of magnitude.


title:
Relations between the generalized Bessel functions and the Janowski
  class

abstract:
  We are interested in finding the sufficient conditions on $A$, $B$,
$\lambda$, $b$ and $c$ which ensure that the generalized Bessel functions
${u}_{\lambda}:={u}_{\lambda,b,c}$ satisfies the subordination
${u}_{\lambda}(z) \prec (1+Az)/ (1+Bz)$. Also, conditions for which
${u}_{\lambda}(z)$ to be Janowski convex, and $z{u}'_{\lambda}(z)$ to be
Janowski starlike in the unit disk $\mathbb{D}=\{z \in \mathbb{C}: |z|<1\}$ are
obtained.


title: Certain results on $q$-starlike and $q$-convex error functions

abstract:
  The error function occurs widely in multiple areas of mathematics,
mathematical physics and natural sciences. There has been no work in this area
for the past four decades. In this article, we estimate the coefficient bounds
with q-difference operator for certain classes of the spirallike starlike and
convex error function associated with convolution product using subordination
as well as quasi-subordination. Though this concept is an untrodden path in the
field of complex function theory, it will prove to be an encouraging future
study for researchers on error function.


title:
Looking for bound states and resonances in the $\eta^\prime K\bar K$
  system

abstract:
  Motivated by the continuous experimental investigations of $X(1835)$ in
three-body decay channels like $\eta^\prime \pi^+ \pi^-$, we investigate the
$\eta^\prime K \bar K$ system with the aim of searching for bound states and/or
resonances when the dynamics involved in the $K\bar K$ subsystem can form the
resonances: $f_0(980)$ in isospin 0 or $a_0(980)$ in isospin 1. For this, we
solve the Faddeev equations for the three-body system. The input two-body
$t$-matrices are obtained by solving Bethe-Salpeter equations in a coupled
channel formalism. As a result, no signal of a three-body bound state or
resonance is found.


title: On the spin geometry of supergravity and string theory

abstract:
  We summarize the main results of our recent investigation of bundles of real
Clifford modules and briefly touch on some applications to string theory and
supergravity.


title: Zero-Shot Visual Recognition via Bidirectional Latent Embedding

abstract:
  Zero-shot learning for visual recognition, e.g., object and action
recognition, has recently attracted a lot of attention. However, it still
remains challenging in bridging the semantic gap between visual features and
their underlying semantics and transferring knowledge to semantic categories
unseen during learning. Unlike most of the existing zero-shot visual
recognition methods, we propose a stagewise bidirectional latent embedding
framework to two subsequent learning stages for zero-shot visual recognition.
In the bottom-up stage, a latent embedding space is first created by exploring
the topological and labeling information underlying training data of known
classes via a proper supervised subspace learning algorithm and the latent
embedding of training data are used to form landmarks that guide embedding
semantics underlying unseen classes into this learned latent space. In the
top-down stage, semantic representations of unseen-class labels in a given
label vocabulary are then embedded to the same latent space to preserve the
semantic relatedness between all different classes via our proposed
semi-supervised Sammon mapping with the guidance of landmarks. Thus, the
resultant latent embedding space allows for predicting the label of a test
instance with a simple nearest-neighbor rule. To evaluate the effectiveness of
the proposed framework, we have conducted extensive experiments on four
benchmark datasets in object and action recognition, i.e., AwA, CUB-200-2011,
UCF101 and HMDB51. The experimental results under comparative studies
demonstrate that our proposed approach yields the state-of-the-art performance
under inductive and transductive settings.


title:
Measure of relative $(p,q)$-th order based on a growth of composite
  entire functions

abstract:
  We deduce some growth properties of composite entire functions in the light
of their relative $(p,q)$\ th order by extending some results of J. Tu, Z. X.
Chen and X. M. Zheng.


title: Large scale geometry of homeomorphism groups

abstract:
  Let M be a compact manifold. We show the identity component
$\mathrm{Homeo}_0(M)$ of the group of self-homeomorphisms of M has a
well-defined quasi-isometry type, and study its large scale geometry. Through
examples, we relate this large scale geometry to both the topology of M and the
dynamics of group actions on M. This gives a rich family of examples of
non-locally compact groups to which one can apply the large-scale methods
developed in previous work of the second author.


title: In-gap corner states in core-shell polygonal quantum rings

abstract:
  We study Coulomb interacting electrons confined in polygonal quantum rings.
We focus on the interplay of localization at the polygon corners and Coulomb
repulsion. Remarkably, the Coulomb repulsion allows the formation of in-gap
states, i.e. corner-localized states of electron pairs or clusters shifted to
energies that were forbidden for uncoupled electrons, but below the energies of
side-localized states. We also specify conditions allowing optical excitation
of those states.


title: Solar Coronal Jets: Observations, Theory, and Modeling

abstract:
  Coronal jets represent important manifestations of ubiquitous solar
transients, which may be the source of significant mass and energy input to the
upper solar atmosphere and the solar wind. While the energy involved in a
jet-like event is smaller than that of "nominal" solar flares and coronal mass
ejections (CMEs), jets share many common properties with these phenomena, in
particular, the explosive magnetically driven dynamics. Studies of jets could,
therefore, provide critical insight for understanding the larger, more complex
drivers of the solar activity. On the other side of the size-spectrum, the
study of jets could also supply important clues on the physics of transients
close or at the limit of the current spatial resolution such as spicules.
Furthermore, jet phenomena may hint to basic process for heating the corona and
accelerating the solar wind; consequently their study gives us the opportunity
to attack a broad range of solar-heliospheric problems.


title:
Predicting and Understanding Law-Making with Word Vectors and an
  Ensemble Model

abstract:
  Out of nearly 70,000 bills introduced in the U.S. Congress from 2001 to 2015,
only 2,513 were enacted. We developed a machine learning approach to
forecasting the probability that any bill will become law. Starting in 2001
with the 107th Congress, we trained models on data from previous Congresses,
predicted all bills in the current Congress, and repeated until the 113th
Congress served as the test. For prediction we scored each sentence of a bill
with a language model that embeds legislative vocabulary into a
high-dimensional, semantic-laden vector space. This language representation
enables our investigation into which words increase the probability of
enactment for any topic. To test the relative importance of text and context,
we compared the text model to a context-only model that uses variables such as
whether the bill's sponsor is in the majority party. To test the effect of
changes to bills after their introduction on our ability to predict their final
outcome, we compared using the bill text and meta-data available at the time of
introduction with using the most recent data. At the time of introduction
context-only predictions outperform text-only, and with the newest data
text-only outperforms context-only. Combining text and context always performs
best. We conducted a global sensitivity analysis on the combined model to
determine important variables predicting enactment.


title:
An internal disulfide locks a misfolded aggregation-prone intermediate
  in cataract-linked mutants of human {\gamma}D-crystallin

abstract:
  Considerable mechanistic insight has been gained into amyloid aggregation;
however, a large class of non-amyloid protein aggregates are considered
'amorphous,' and in most cases little is known about their mechanisms.
Amorphous aggregation of {\gamma}-crystallins in the eye lens causes a
widespread disease of aging, cataract. We combined simulations and experiments
to study the mechanism of aggregation of two {\gamma}D-crystallin mutants, W42R
and W42Q - the former a congenital cataract mutation, and the latter a mimic of
age-related oxidative damage. We found that formation of an internal disulfide
was necessary and sufficient for aggregation under physiological conditions.
Two-chain all-atom simulations predicted that one non-native disulfide in
particular, between Cys32 and Cys41, was likely to stabilize an unfolding
intermediate prone to intermolecular interactions. Mass spectrometry and
mutagenesis experiments confirmed the presence of this bond in the aggregates
and its necessity for oxidative aggregation under physiological conditions in
vitro. Mining the simulation data linked formation of this disulfide to
extrusion of the N-terminal \b{eta}-hairpin and rearrangement of the native
\b{eta}-sheet topology. Specific binding between the extruded hairpin and a
distal \b{eta}-sheet, in an intermolecular chain reaction similar to domain
swapping, is the most probable mechanism of aggregate propagation.


title: A Breakthrough in Sphere Packing: The Search for Magic Functions

abstract:
  This paper is an exposition, written for the Nieuw Archief voor Wiskunde,
about the two recent breakthrough results in the theory of sphere packings. It
includes an interview with Henry Cohn, Abhinav Kumar, Stephen D. Miller, and
Maryna Viazovska.


title: Quantum dynamics of a driven two-level molecule with variable dephasing

abstract:
  The longitudinal ($\Gamma_1$) and transverse ($\Gamma_2$) decay rates of a
two-level quantum system have profound influence on its evolution. Atomic
systems with $\Gamma_2=\tfrac{1}{2}\Gamma_1$ have been studied extensively, but
with the rise of solid-state quantum devices it is also important to consider
the effect of stronger transverse relaxation due to interactions with the solid
environment. Here we study the quantum dynamics of a single organic dye
molecule driven by a laser. We measure the variation of $\Gamma_2$ with
temperature and determine the activation energy for thermal dephasing of the
optical dipole. Then we measure the second-order correlation function
$g^{(2)}(\tau)$ of the light emitted by the molecule for various ratios
$\Gamma_2/\Gamma_1$ and saturation parameters $S$. We show that the general
solution to the optical Bloch equations accurately describes the observed
quantum dynamics over a wide range of these parameters, and we discuss the
limitations of the various approximate expressions for $g^{(2)}(\tau)$ that
appear in the literature.


title:
Pattern formation in a complex Swift-Hohenberg equation with phase
  bistability

abstract:
  We study pattern formation in a complex Swift Hohenberg equation with
phase-sensitive (parametric) gain. Such an equation serves as a universal order
parameter equation describing the onset of spontaneous oscillations in extended
systems submitted to a kind of forcing dubbed rocking when the instability is
towards long wavelengths. Applications include two-level lasers and
photorefractive oscillators. Under rocking, the original continuous phase
symmetry of the system is replaced by a discrete one, so that phase bistability
emerges. This leads to the spontaneous formation of phase-locked spatial
structures like phase domains and dark-ring (phase-) cavity solitons. Stability
of the homogeneous solutions is studied and numerical simulations are made
covering all the dynamical regimes of the model, which turn out to be very
rich. Formal derivations of the rocked complex Swift-Hohenberg equation, using
multiple scale techniques, are given for the two-level laser and the
photorefractive oscillator.


title:
Totally Ordered Measured Trees and Splitting Trees with Infinite
  Variation

abstract:
  Combinatorial trees can be used to represent genealogies of asexual
individuals. These individuals can be endowed with birth and death times, to
obtain a so-called `chronological tree'. In this work, we are interested in the
continuum analogue of chronological trees in the setting of real trees. This
leads us to consider totally ordered and measured trees, abbreviated as TOM
trees. First, we define an adequate space of TOM trees and prove that under
some mild conditions, every compact TOM tree can be represented in a unique way
by a so-called contour function, which is right-continuous, admits limits from
the left and has non-negative jumps. The appropriate notion of contour function
is also studied in the case of locally compact TOM trees. Then we study the
splitting property of (measures on) TOM trees which extends the notion of
`splitting tree' studied in \cite{MR2599603}, where during her lifetime, each
individual gives birth at constant rate to independent and identically
distributed copies of herself. We prove that the contour function of a TOM tree
satisfying the splitting property is associated to a spectrally positive L\'evy
process that is not a subordinator, both in the critical and subcritical cases
of compact trees as well as in the supercritical case of locally compact trees.


title:
Entanglement of Vacuum States With the de Sitter Horizon: Consequences
  on Holographic Dark Energy

abstract:
  The aim of this article is to study the effect of an Event Horizon on the
entanglement of the Quantum Vacuum and how entanglement, together with the
Holographic Principle, may explain the current value of the Cosmological
Constant, in light of recent theories. Entanglement is tested for vacuum states
very near and very far from the Horizon of a de Sitter Universe, using the
Peres-Horodecki (PPT) criterion. A scalar vacuum field ($\hat{\phi}$) is
averaged inside two boxes of volume $V$ in different spatial positions such
that it acquires the structure of a bipartite Quantum Harmonic Oscillator, for
which the PPT criterion is a necessary but not sufficient condition of
separability. Entanglement is found between states obtained from boxes shaped
as spherical shells with thickness of the order of one Planck distance ($l_p$),
when one of the states is near the Horizon, and the other state is anywhere in
the Universe. Entanglement disappears when the distance of the state near the
horizon and the Horizon increases to around $5l_p$. If we consider the Horizon
not as a surface but as a spherical shell of thickness $l_p$, then this means
that there is entanglement between the states in the Horizon and the rest of
the Universe. When both states are at distances larger than $\sim 5 l_p$ from
the Horizon, no entanglement is found.


title:
Diffusivity and Hydrodynamic Drag of Nanoparticles at a Vapor-liquid
  Interface

abstract:
  Measurements of the surface diffusivity of colloidal spheres translating
along a vapor/liquid inter- face show an unexpected decrease in diffusivity, or
increase in surface drag (from the Stokes-Einstein relation) when the particles
situate further into the vapor phase. However, direct measurements of the
surface drag from the colloid velocity due to an external force find the
expected decrease with deeper immersion into the vapor. The paradoxical drag
increase observed in diffusion experiments has been attributed to the
attachment of the fluid interface to heterogeneities on the colloid surface,
which causes the interface, in response to thermal fluctuations, to either jump
or remain pinned, creating added drag. We have performed molecular dynamics
simulations of the diffusivity and force experiments for a nanoparticle with a
rough surface at a vapor/liquid interface to examine the effect of contact line
fluctuations. The drag calculated from both experiments agree and decrease as
the particle positions further into the vapor. The surface drag is smaller than
the bulk liquid drag due to the partial submersion into the liquid, and the
finite thickness of the interfacial zone relative to the nanoparticle size.
Contact line fluctuations do not give rise to an anomalous increase in drag.


title: A categorification of a quantum Frobenius map

abstract:
  A quantum Frobenius map a la Lusztig for $\mathfrak{sl}_2$ is categorified at
a prime root of unity.


title:
Analysis of a hybridized/interface stabilized finite element method for
  the Stokes equations

abstract:
  Stability and error analysis of a hybridized discontinuous Galerkin finite
element method for Stokes equations is presented. The method is locally
conservative, and for particular choices of spaces the velocity field is
point-wise solenoidal. It is shown that the method is inf-sup stable for both
equal-order and locally Taylor--Hood type spaces, and \emph{a priori} error
estimates are developed. The considered method can be constructed to have the
same global algebraic structure as a conforming Galerkin method, unlike
standard discontinuous Galerkin methods that have greater number of degrees of
freedom than conforming Galerkin methods on a given mesh. We assert that this
method is amongst the simplest and most flexible finite element approaches for
Stokes flow that provide local mass conservation. With this contribution the
mathematical basis is established, and this supports the performance of the
method that has been observed experimentally in other works.


title:
Strong Lensing Analysis of the Powerful Lensing Cluster MACS
  J2135.2-0102 ($z$=0.33)

abstract:
  We present a light-traces-mass (LTM) strong-lensing model of the massive
lensing cluster MACS J2135.2-0102 ($z$=0.33; hereafter MACS2135), known in part
for hosting the Cosmic Eye galaxy lens. MACS2135 is also known to multiply-lens
a $z=$2.3 sub-mm galaxy near the Brightest Cluster Galaxy (BCG), as well as a
prominent, triply-imaged system at a large radius of $\sim$37" south of the
BCG. We use the latest available Hubble imaging to construct an accurate
lensing model for this cluster, identifying six new multiply-imaged systems
with the guidance of our LTM method, so that we have roughly quadrupled the
number of lensing constraints. We determine that MACS2135 is amongst the top
lensing clusters known, comparable in size to the Hubble Frontier Fields. For a
source at $z_{s}=2.32$, we find an effective Einstein radius of
$\theta_{e}=27\pm3$", enclosing $1.12 \pm0.16 \times10^{14}$ $M_{\odot}$. We
make our lens model, including mass and magnification maps, publicly available,
in anticipation of searches for high-$z$ galaxies with the James Webb Space
Telescope for which this cluster is a compelling target.


title: Survey strategy optimization for the Atacama Cosmology Telescope

abstract:
  In recent years there have been significant improvements in the sensitivity
and the angular resolution of the instruments dedicated to the observation of
the Cosmic Microwave Background (CMB). ACTPol is the first polarization
receiver for the Atacama Cosmology Telescope (ACT) and is observing the CMB sky
with arcmin resolution over about 2000 sq. deg. Its upgrade, Advanced ACTPol
(AdvACT), will observe the CMB in five frequency bands and over a larger area
of the sky. We describe the optimization and implementation of the ACTPol and
AdvACT surveys. The selection of the observed fields is driven mainly by the
science goals, that is, small angular scale CMB measurements, B-mode
measurements and cross-correlation studies. For the ACTPol survey we have
observed patches of the southern galactic sky with low galactic foreground
emissions which were also chosen to maximize the overlap with several galaxy
surveys to allow unique cross-correlation studies. A wider field in the
northern galactic cap ensured significant additional overlap with the BOSS
spectroscopic survey. The exact shapes and footprints of the fields were
optimized to achieve uniform coverage and to obtain cross-linked maps by
observing the fields with different scan directions. We have maximized the
efficiency of the survey by implementing a close to 24 hour observing strategy,
switching between daytime and nighttime observing plans and minimizing the
telescope idle time. We describe the challenges represented by the survey
optimization for the significantly wider area observed by AdvACT, which will
observe roughly half of the low-foreground sky. The survey strategies described
here may prove useful for planning future ground-based CMB surveys, such as the
Simons Observatory and CMB Stage IV surveys.


title:
Understanding and controlling the work function of perovskite oxides
  using Density Functional Theory

abstract:
  Perovskite oxides containing transition metals are promising materials in a
wide range of electronic and electrochemical applications. However, neither
their work function values nor an understanding of their work function physics
have been established. Here, we predict the work function trends of a series of
perovskite ($ABO_3$ formula) materials using Density Functional Theory, and
show that the work functions of (001)-terminated AO- and $BO_2$-oriented
surfaces can be described using concepts of electronic band filling, bond
hybridization, and surface dipoles. The calculated range of AO ($BO_2$) work
functions are 1.60-3.57 eV (2.99-6.87 eV). We find an approximately linear
correlation ($R^2$ between 0.77-0.86, depending on surface termination) between
work function and position of the oxygen 2p band center, which correlation
enables both understanding and rapid prediction of work function trends.
Furthermore, we identify $SrVO_3$ as a stable, low work function, highly
conductive material. Undoped (Ba-doped) $SrVO_3$ has an intrinsically low
AO-terminated work function of 1.86 eV (1.07 eV). These properties make
$SrVO_3$ a promising candidate material for a new electron emission cathode for
application in high power microwave devices, and as a potential electron
emissive material for thermionic energy conversion technologies.


title: The sequence of middle divisors is unbounded

abstract:
  The sequence of middle divisors is shown to be unbounded. For a given number
$n$, $a_{n,0}$ is the number of divisors of $n$ in between $\sqrt{n/2}$ and
$\sqrt{2n}$. We explicitly construct a sequence of numbers $n(i)$ and a list of
divisors in the interesting range, so that the length of the list goes to
infinity as $i$ increases.


title:
The Effects of the modified scalar product on the properties of the
  one-dimensional harmonic oscillator with energy-dependent potential

abstract:
  In this article, we try to test the influence of the modification of the
scalar product, found in the problems of the energy-dependent potential, on the
physical properties of the harmonic oscillator in one dimension. For this, we
at first discuss the effect of this change on the thermodynamic properties of
this oscillator, and then on the parameter of Fisher, well known in the field
of quantum information. For the second problem, we are an obligation to
redefine this parameter. Finally, the uncertainly relation of Cramer-Rao is
well recovered in our problem in question.


title: Morphological Transitions during Melting of Small Cylindrical Aggregates

abstract:
  Most studies on melting under confinement focus only on the solid and liquid
melt phases. Despite of its ubiquity, contributions from the capillary
interface (liquid / vapor interface) are often neglected. In this study the
melting behavior of small cylindrical aggregates in vapor attached to planar
surfaces is analyzed. For the assumed boundary conditions (cylindrical solid
with a non wetting top plane and a wettable side wall) solid and the liquid
phases can coexist within a certain temperature range. Due to capillary
instability, the liquid phase can form either an axisymmetric rouloid
morphology or, above a certain threshold liquid volume fraction, a bulge
coexisting with a rouloid-like section. The corresponding melting points are
different. The analysis explicitly describes the behavior of a real system of
small aggregates of long chain alkanes on planar substrates. It also gives
qualitative insights into the melting behavior of small aggregates with
anisotropic wetting behaviors in general. It reveals in particular how melting
points and melting pathways depend on the energetic respectively morphological
pathways leading to complete melting.


title: Lithium transport through Lithium-ion battery cathode coatings

abstract:
  The surface coating of cathodes using insulator films has proven to be a
promising method for high-voltage cathode stabilization in Li-ion batteries.
However, there is still substantial uncertainty about how these films function,
specifically with regard to important coating design principles such as lithium
solubility and transport through the films. This study uses Density Functional
Theory to examine the diffusivity of interstitial lithium in crystalline
{\alpha}-$AlF_3$, {\alpha}-$Al_2O_3$, m-$ZrO_2$, c-MgO, and {\alpha}-quartz
$SiO_2$, which provide benchmark cases for further understanding of insulator
coatings in general. In addition, we propose an Ohmic electrolyte model to
predict resistivities and overpotential contributions under battery operating
conditions. For the crystalline materials considered we predict that Li+
diffuses quite slowly, with a migration barrier larger than 0.9 eV in all
crystalline materials except {\alpha}-quartz $SiO_2$, which is predicted to
have a migration barrier of 0.276 eV along <001>. These results suggest that
the stable crystalline forms of these insulator materials, except for oriented
{\alpha}-quartz $SiO_2$, are not practical for conformal cathode coatings.
Amorphous $Al_2O_3$ and $AlF_3$ have higher Li+ diffusivities than their
crystalline counterparts. Our predicted amorphous $Al_2O_3$ resistivity (1789
M{\Omega}m) is near the top of the range of fitted resistivities extracted from
previous experiments on nominal $Al_2O_3$ coatings (7.8 to 913 M{\Omega}m)
while our predicted amorphous $AlF_3$ resistivity (114 M{\Omega}m) is close to
the middle of the range. These comparisons support our framework for modeling
and understanding the impact on overpotential of conformal coatings in terms of
their fundamental thermodynamic and kinetic properties, and support that these
materials can provide practical conformal coatings in their amorphous form.


title:
Anharmonicity of multi-octupole-phonon excitations in $^{208}$Pb:
  analysis with multi-reference covariant density functional theory and
  subbarrier fusion of $^{16}$O+$^{208}$Pb

abstract:
  We discuss anharmonicity of the multi-octupole-phonon states in $^{208}$Pb
based on a covariant density functional theory, by fully taking into account
the interplay between the quadrupole and the octupole degrees of freedom. Our
results indicate the existence of a large anharmonicity in the transition
strengths, even though the excitation energies are similar to those in the
harmonic limit. We also show that the quadrupole-shape fluctuation
significantly enhances the fragmentation of the two-octupole-phonon states in
$^{208}$Pb. Using those transition strengths as inputs to coupled channels
calculations, we then discuss the fusion reaction of $^{16}$O+$^{208}$Pb at
energies around the Coulomb barrier. We show that the anharmonicity of the
octupole vibrational excitation considerably improves previous coupled-channels
calculations in the harmonic oscillator limit, significantly reducing the
height of the main peak in the fusion barrier distribution.


title:
Numeric modeling of synchronous laser pulsing and voltage pulsing field
  evaporation

abstract:
  We have recently proposed an atom probe design based on a femtosecond
time-resolved pump-probe setup. This setup unlocks the limitation of voltage
pulsed mode atom probe thanks to the occurrence of local photoconductive
switching effect . In this paper, we have used a numerical model to simulate
the field evaporation process triggered by the synchronous two pulses. The
model takes into account the local photoconductive effect and the temperature
rise caused by the laser application and the voltage pulse distortion due to
the RC effect.


title:
Origins of Large Voltage Hysteresis in High Energy-Density Metal
  Fluoride Lithium-Ion Battery Conversion Electrodes

abstract:
  Metal fluoride and oxides can store multiple lithium-ions through conversion
chemistry to enable high energy-density lithium-ion batteries. However, their
practical applications have been hindered by an unusually large voltage
hysteresis between charge and discharge voltage-profiles and the consequent low
energy efficiency (< 80%). The physical origins of such hysteresis are rarely
studied and poorly understood. Here we employ in situ X-ray absorption
spectroscopy (XAS), transmission electron microscopy (TEM),
density-functional-theory (DFT) calculations, and galvanostatic intermittent
titration technique (GITT) to first correlate the voltage profile of iron
fluoride ($FeF_3$), a representative conversion electrode material, with
evolution and spatial distribution of intermediate phases in the electrode. The
results reveal that, contrary to conventional belief, the phase evolution in
the electrode is symmetrical during discharge and charge. However, the spatial
evolution of the electrochemically active phases, which is controlled by
reaction kinetics, is different. We further propose that the voltage hysteresis
in the $FeF_3$ electrode is kinetic in nature. It is the result of Ohmic
voltage drop, reaction overpotential, and different spatial distributions of
electrochemically-active phases (i.e. compositional inhomogeneity). Therefore,
the large hysteresis can be expected to be mitigated by rational design and
optimization of material microstructure and electrode architecture to improve
the energy efficiency of lithium-ion batteries based on conversion chemistry.


title: The Assouad dimension of self-affine carpets with no grid structure

abstract:
  Previous study of the Assouad dimension of planar self-affine sets has relied
heavily on the underlying IFS having a `grid structure', thus allowing for the
use of approximate squares. We study the Assouad dimension of a class of
self-affine carpets which do not have an associated grid structure. We find
that the Assouad dimension is related to the box and Assouad dimensions of the
(self-similar) projection of the self-affine set onto the first coordinate and
to the local dimensions of the projection of a natural Bernoulli measure onto
the first coordinate. In a special case we relate the Assouad dimension of the
Przytycki-Urba\'nski sets to the lower local dimensions of Bernoulli
convolutions.


title:
Linear Quadratic Mean Field Type Control and Mean Field Games with
  Common Noise, with Application to Production of an Exhaustible Resource

abstract:
  We study a general linear quadratic mean field type control problem and
connect it to mean field games of a similar type. The solution is given both in
terms of a forward/backward system of stochastic differential equations and by
a pair of Riccati equations. In certain cases, the solution to the mean field
type control is also the equilibrium strategy for a class of mean field games.
We use this fact to study an economic model of production of exhaustible
resources.
  Keywords: mean field type control, mean field games, linear-quadratic,
optimal control, riccati equations, exhaustible resource production


title: Recovering the topology of surfaces from cluster algebras

abstract:
  We present an effective method for recovering the topology of a bordered
oriented surface with marked points from its cluster algebra. The information
is extracted from the maximal triangulations of the surface, those that have
exchange quivers with maximal number of arrows in the mutation class. The
method gives new proofs of the automorphism and isomorphism problems for the
surface cluster algebras, as well as the uniqueness of the
Fomin-Shapiro-Thurston block decompositions of the exchange quivers of the
surface cluster algebras. The previous proofs of these results followed a
different approach based on Gu's direct proof of the last result. The method
also explains the exceptions to these results due to pathological problems with
the maximal triangulations of several surfaces.


title:
A hot big bang theory: magnetic fields and the early evolution of the
  protolunar disk

abstract:
  The leading theory for the formation of the Earth's moon invokes a collision
between a Mars-sized body and the proto-Earth to produce a disk of orbiting
material that later condenses to form the Moon. Here we study the early
evolution of the protolunar disk. First, we show that the disk opacity is large
and cooling is therefore inefficient (t_{cool} \Omega >> 1). In this regime
angular momentum transport in the disk leads to steady heating unless \alpha <
(t_{cool} \Omega)^{-1} << 1. Following earlier work by Charnoz and Michaut, and
Carballido et al., we show that once the disk is completely vaporized it is
well coupled to the magnetic field. We consider a scenario in which turbulence
driven by magnetic fields leads to a brief, hot phase where the disk is
geometrically thick, wit h strong turbulent mixing. The disk cools by spreading
until it decouples from the field. We point out that approximately half the
accretion energy is dissipated in the boundary layer where the disk meets the
Earth's surface. This creates high entropy material close to the Earth, driving
convection and mixing. Finally, a hot, magnetized disk could drive bipolar
outflows that remove mass and angular momentum from the Earth-Moon system.


title:
Extreme Scaling of Supercomputing with Stranded Power: Costs and
  Capabilities

abstract:
  Power consumption (supply, heat, cost) and associated carbon emissions
(environmental impact) are increasingly critical challenges in scaling
supercomputing to Exascale and beyond. We proposes to exploit stranded power,
renewable energy that has no value to the power grid, for scaling
supercomputers, Zero-Carbon Cloud (ZCCloud), and showing that stranded power
can be employed effectively to expand computing [1]. We build on those results
with a new analysis of stranded power, characterizing temporal, geographic, and
interval properties. We simulate production supercomputing workloads and model
datacenter total-cost-of-ownership (TCO), assessing the costs and capabilities
of stranded-power based supercomputing. Results show that the ZCCloud approach
is cost-effective today in regions with high cost power. The ZCCloud approach
reduces TCO by 21-45%, and improves cost-effectiveness up to 34%. We study many
scenarios. With higher power price, cheaper computing hardware and higher
system power density, benefits rise to 55%, 97% and 116% respectively. Finally,
we study future extreme-scale systems, showing that beyond terascale, projected
power requirements in excess of 100MW make ZCCloud up to 45% lower cost, for a
fixed budget, increase peak PFLOPS achievable by 80%.


title:
Bounding the Complexity of Replica Symmetry Breaking for Spherical Spin
  Glasses

abstract:
  In this paper, we study the Crisanti-Sommers variational problem, which is a
variational formula for the free energy of spherical mixed $p$-spin glasses. We
begin by computing the dual of this problem using a min-max argument. We find
that the dual is a 1-D problem of obstacle type, where the obstacle is related
to the covariance structure of the underlying process. This approach yields an
alternative way to understand Replica Symmetry Breaking at the level of the
variational problem through topological properties of the coincidence set of
the optimal dual variable. Using this duality, we give an algorithm to reduce
this a priori infinite dimensional variational problem to a finite dimensional
one, thereby confining all possible forms of Replica Symmetry Breaking in these
models to a finite parameter family. These results complement the authors'
related results for the low temperature $\Gamma$-limit of this variational
problem. We briefly discuss the analysis of the Replica Symmetric phase using
this approach.


title: Finding binomials in polynomial ideals

abstract:
  We describe an algorithm which finds binomials in a given ideal
$I\subset\mathbb{Q}[x_1,\dots,x_n]$ and in particular decides whether binomials
exist in $I$ at all. Binomials in polynomial ideals can be well hidden. For
example, the lowest degree of a binomial cannot be bounded as a function of the
number of indeterminates, the degree of the generators, or the
Castelnuovo--Mumford regularity. We approach the detection problem by reduction
to the Artinian case using tropical geometry. The Artinian case is solved with
algorithms from computational number theory.


title:
Distinct magnetic spectra in the hidden order and antiferromagnetic
  phases in URu2-xFexSi2

abstract:
  We use neutron scattering to compare the magnetic excitations in the hidden
order (HO) and antiferromagnetic (AFM) phases in URu2-xFexSi2 as a function of
Fe concentration. The magnetic excitation spectra change significantly between
x = 0.05 and x = 0.10, following the enhancement of the AFM ordered moment, in
good analogy to the behavior of the parent compound under applied pressure.
Prominent lattice-commensurate low-energy excitations characteristic of the HO
phase vanish in the AFM phase. The magnetic scattering is dominated by strong
excitations along the Brillouin zone edges, underscoring the important role of
electron hybridization to both HO and AFM phases, and the similarity of the
underlying electronic structure. The stability of the AFM phase is correlated
with enhanced local-itinerant electron hybridization.


title:
Fundamental Parameters of Main-Sequence Stars in an Instant with Machine
  Learning

abstract:
  Owing to the remarkable photometric precision of space observatories like
Kepler, stellar and planetary systems beyond our own are now being
characterized en masse for the first time. These characterizations are pivotal
for endeavors such as searching for Earth-like planets and solar twins,
understanding the mechanisms that govern stellar evolution, and tracing the
dynamics of our Galaxy. The volume of data that is becoming available, however,
brings with it the need to process this information accurately and rapidly.
While existing methods can constrain fundamental stellar parameters such as
ages, masses, and radii from these observations, they require substantial
computational efforts to do so.
  We develop a method based on machine learning for rapidly estimating
fundamental parameters of main-sequence solar-like stars from classical and
asteroseismic observations. We first demonstrate this method on a
hare-and-hound exercise and then apply it to the Sun, 16 Cyg A & B, and 34
planet-hosting candidates that have been observed by the Kepler spacecraft. We
find that our estimates and their associated uncertainties are comparable to
the results of other methods, but with the additional benefit of being able to
explore many more stellar parameters while using much less computation time. We
furthermore use this method to present evidence for an empirical diffusion-mass
relation. Our method is open source and freely available for the community to
use.
  The source code for all analyses and for all figures appearing in this
manuscript can be found electronically at
https://github.com/earlbellinger/asteroseismology


title:
On Relaxed Averaged Alternating Reflections (RAAR) Algorithm for Phase
  Retrieval from Structured Illuminations

abstract:
  In this paper, as opposed to the random phase masks, the structured
illuminations with a pixel-dependent deterministic phase shift are considered
to derandomize the model setup. The RAAR algorithm is modified to adapt to two
or more diffraction patterns, and the modified RAAR algorithm operates in
Fourier domain rather than space domain. The local convergence of the RAAR
algorithm is proved by some eigenvalue analysis. Numerical simulations is
presented to demonstrate the effectiveness and stability of the algorithm
compared to the HIO (Hybrid Input-Output) method. The numerical performances
show the global convergence of the RAAR in our tests.


title:
Detection of the pairwise kinematic Sunyaev-Zel'dovich effect with BOSS
  DR11 and the Atacama Cosmology Telescope

abstract:
  We present a new measurement of the kinematic Sunyaev-Zeldovich effect using
data from the Atacama Cosmology Telescope (ACT) and the Baryon Oscillation
Spectroscopic Survey (BOSS). Using 600 square degrees of overlapping sky area,
we evaluate the mean pairwise baryon momentum associated with the positions of
50,000 bright galaxies in the BOSS DR11 Large Scale Structure catalog. A
non-zero signal arises from the large-scale motions of halos containing the
sample galaxies. The data fits an analytical signal model well, with the
optical depth to microwave photon scattering as a free parameter determining
the overall signal amplitude. We estimate the covariance matrix of the mean
pairwise momentum as a function of galaxy separation, using microwave sky
simulations, jackknife evaluation, and bootstrap estimates. The most
conservative simulation-based errors give signal-to-noise estimates between 3.6
and 4.1 for varying galaxy luminosity cuts. We discuss how the other error
determinations can lead to higher signal-to-noise values, and consider the
impact of several possible systematic errors. Estimates of the optical depth
from the average thermal Sunyaev-Zeldovich signal at the sample galaxy
positions are broadly consistent with those obtained from the mean pairwise
momentum signal.


title:
Electromagnetic Luminosity of the Coalescence of Charged Black Hole
  Binaries

abstract:
  The observation of a possible electromagnetic counterpart by the Fermi GBM
group to the aLIGO detection of the merger of a black hole binary has spawned a
number of ideas about its source. Furthermore, observations of fast radio
bursts (FRBs) have similarly resulted in a range of new models that might endow
black hole binaries with electromagnetic signatures. In this context, even the
unlikely idea that astrophysical black holes may have significant charge is
worth exploring, and here we present results from the simulation of weakly
charged black holes as they orbit and merge. Our simulations suggest that a
black hole binary with mass comparable to that observed in GW150914 could
produce the level of electromagnetic luminosity observed by Fermi GBM
($10^{49}$ ergs/s) with a non-dimensional charge of $q \equiv Q/M = 10^{-4}$
assuming good radiative efficiency. However even a charge such as this is
difficult to imagine avoiding neutralization long enough for the binary to
produce its electromagnetic counterpart, and so this value would likely serve
simply as an upper bound. On the other hand, one can equivalently consider the
black holes as having acquired a magnetic monopole charge that would be easy to
maintain and would generate an identical electromagnetic signature as the
electric charges. The observation of such a binary would have significant
cosmological implications, not the least of which would be an explanation for
the quantization of charge itself. We also study such a magnetically charged
binary in the force-free regime and find it much more radiative, reducing even
further the requirements to produce the counterpart.


title:
Bar-driven evolution and quenching of spiral galaxies in cosmological
  simulations

abstract:
  We analyse the output of the hi-res cosmological zoom-in simulation ErisBH to
study self-consistently the formation of a strong stellar bar in a Milky
Way-type galaxy and its effect on the galactic structure, on the central gas
distribution and on star formation. The simulation includes radiative cooling,
star formation, SN feedback and a central massive black hole which is
undergoing gas accretion and is heating the surroundings via thermal AGN
feedback. A large central region in the ErisBH disk becomes bar-unstable after
z~1.4, but a clear bar-like structure starts to grow significantly only after
z~0.4, possibly triggered by the interaction with a massive satellite. At z~0.1
the bar reaches its maximum radial extent of l~2.2 kpc. As the bar grows, it
becomes prone to buckling instability, which we quantify based on the
anisotropy of the stellar velocity dispersion. The actual buckling event is
observable at z~0.1, resulting in the formation of a boxy-peanut bulge clearly
discernible in the edge-on view of the galaxy at z=0. The bar in ErisBH does
not dissolve during the formation of the bulge but remains strongly
non-axisymmetric down to the resolution limit of ~100 pc at z=0. During its
early growth, the bar exerts a strong torque on the gas within its extent and
drives gas inflows that enhance the nuclear star formation on sub-kpc scales.
Later on the infalling gas is nearly all consumed into stars and, to a lesser
extent, accreted onto the central black hole, leaving behind a gas-depleted
region within the central ~2 kpc. Observations would more likely identify a
prominent, large-scale bar at the stage when the galactic central region has
already been quenched. Bar-driven quenching may play an important role in
disk-dominated galaxies at all redshift. [Abridged]


title:
Integrating out heavy particles with functional methods: a simplified
  framework

abstract:
  We present a systematic procedure to obtain the one-loop low-energy effective
Lagrangian resulting from integrating out the heavy fields of a given
ultraviolet theory. We show that the matching coefficients are determined
entirely by the hard region of the functional determinant involving the heavy
fields. This represents an important simplification with respect the
conventional matching approach, where the full and effective theory
contributions have to be computed separately and a cancellation of the infrared
divergent parts has to take place. We illustrate the method with a descriptive
toy model and with an extension of the Standard Model with a heavy real scalar
triplet. A comparison with other schemes that have been put forward recently is
also provided.


title: Demonstrating Diversity in Star Formation Histories with the CSI Survey

abstract:
  We present coarse but robust star formation histories (SFHs) derived from
spectro-photometric data of the Carnegie-Spitzer-IMACS Survey, for 22,494
galaxies at 0.3<z<0.9 with stellar masses of 10^9 Msun to 10^12 Msun. Our study
moves beyond "average" SFHs and distribution functions of specific star
formation rates (sSFRs) to individually measured SFHs for tens of thousands of
galaxies. By comparing star formation rates (SFRs) with timescales of 10^10,
10^9, and 10^8 years, we find a wide diversity of SFHs: 'old galaxies' that
formed most or all of their stars early; galaxies that formed stars with
declining or constant SFRs over a Hubble time, and genuinely 'young galaxies'
that formed most of their stars since z=1. This sequence is one of decreasing
stellar mass, but, remarkably, each type is found over a mass range of a factor
of 10. Conversely, galaxies at any given mass follow a wide range of SFHs,
leading us to conclude that: (1) halo mass does not uniquely determine SFHs;
(2) there is no 'typical' evolutionary track; and (3) "abundance matching" has
limitations as a tool for inferring physics. Our observations imply that SFHs
are set at an early epoch, and that--for most galaxies--the decline and
cessation of star formation occurs over a Hubble-time, without distinct
"quenching" events. SFH diversity is inconsistent with models where galaxy
mass, at any given epoch, grows simply along relations between SFR and stellar
mass, but is consistent with a 2-parameter lognormal form, lending credence to
this model from a new and independent perspective.


title: Black holes in stellar-mass binary systems: expiating original spin?

abstract:
  We investigate systematically whether accreting black hole systems are likely
to reach global alignment of the black hole spin and its accretion disc with
the binary plane. In low-mass X-ray binaries (LMXBs) there is only a modest
tendency to reach such global alignment, and it is difficult to achieve fully:
except for special initial conditions we expect misalignment of the spin and
orbital planes by ~1 radian for most of the LMXB lifetime. The same is expected
in high-mass X-ray binaries (HMXBs). A fairly close approach to global
alignment is likely in most stellar-mass ultraluminous X-ray binary systems
(ULXs) where the companion star fills its Roche lobe and transfers on a thermal
timescale to a black hole of lower mass. These systems are unlikely to show
orbital eclipses, as their emission cones are close to the hole's spin axis.
This offers a potential observational test, as models for ULXs invoking
intermediate-mass black holes do predict eclipses for ensembles of > ~10
systems. Recent observational work shows that eclipses are either absent or
extremely rare in ULXs, supporting the picture that most ULXs are stellar-mass
binaries with companion stars more massive than the accretor.


title:
The Relation between Stellar and Dynamical Surface Densities in the
  Central Regions of Disk Galaxies

abstract:
  We use the SPARC (Spitzer Photometry & Accurate Rotation Curves) database to
study the relation between the central surface density of stars Sstar and
dynamical mass Sdyn in 135 disk galaxies (S0 to dIrr). We find that Sdyn
correlates tightly with Sstar over 4 dex. This central density relation can be
described by a double power law. High surface brightness galaxies are
consistent with a 1:1 relation, suggesting that they are self-gravitating and
baryon dominated in the inner parts. Low surface brightness galaxies
systematically deviate from the 1:1 line, indicating that the dark matter
contribution progressively increases but remains tightly coupled to the stellar
one. The observed scatter is small (~0.2 dex) and largely driven by
observational uncertainties. The residuals show no correlations with other
galaxy properties like stellar mass, size, or gas fraction.


title:
The XXL Survey: IX. Optical overdensity and radio continuum analysis of
  a supercluster at $z=0.43$

abstract:
  We present observations with the Karl G. Jansky Very Large Array (VLA) at 3
GHz toward a sub-field of the XXL-North 25 deg$^{2}$ field targeting the first
supercluster discovered in the XXL Survey. The structure has been found at a
spectroscopic redshift of 0.43 and extending over $0.35\times0.1$ deg$^{2}$ on
the sky. We present the 3 GHz VLA radio continuum observations, the radio
mosaic and radio source catalogue, and, perform an analysis of the supercluster
in the optical and radio regimes using photometric redshifts from the CFHTLS
survey and our new VLA data. Our 3 GHz radio mosaic has a resolution of
$3.2\times1.9$ arcsec$^2$, and covers an area of $41\times41$ arcmin$^2$ with
rms noise level below $\sim20 \mu$Jy beam$^{-1}$ ($\sim11\mu$Jy beam$^{-1}$ in
central $15\times15$ arcmin$^2$). We extract a catalogue of 155 radio sources
$\geq6\sigma$, 8 of which are multicomponent sources, and 123 ($79\%$) can be
associated with optical sources in the CFHTLS W1 catalogue. Applying Voronoi
tessellation analysis (VTA) in the area around the X-ray identified
supercluster we identify a total of 17 overdensities at $z=0.35-0.50$, 7 of
which are associated with clusters detected in the $XMM-Newton$ XXL data. We
find a mean photometric redshift of 0.43 for our overdensities, consistent with
the spectroscopic redshifts of 7 X-ray detected clusters. The full
VTA-identified structure extends over $\sim0.6\times0.2$ deg$^2$ on the sky,
($\sim12\times4$ Mpc$^{2}$ at $z=0.43$). We associate 8 radio sources with
potential group/cluster member galaxies none of which are large radio galaxies.
The spatial distribution of the red and blue potential group member galaxies
suggests that the clusters are dynamically young and not virialised yet, as
expected for hierarchical structure growth in a $\Lambda$CDM universe. Further
spectroscopic data are required to analyze the dynamical state of the groups.


title:
On the Classification of UGC1382 as a Giant Low Surface Brightness
  Galaxy

abstract:
  We provide evidence that UGC1382, long believed to be a passive elliptical
galaxy, is actually a giant low surface brightness (GLSB) galaxy which rivals
the archetypical GLSB Malin 1 in size. Like other GLSB galaxies, it has two
components: a high surface brightness disk galaxy surrounded by an extended low
surface brightness (LSB) disk. For UGC1382, the central component is a
lenticular system with an effective radius of 6 kpc. Beyond this, the LSB disk
has an effective radius of ~38 kpc and an extrapolated central surface
brightness of ~26 mag/arcsec^2. Both components have a combined stellar mass of
~8x10^10 M_sun, and are embedded in a massive (10^10 M_sun) low-density (<3
M_sun/pc^2) HI disk with a radius of 110 kpc, making this one of the largest
isolated disk galaxies known. The system resides in a massive dark matter halo
of at least 2x10^12 M_sun. Although possibly part of a small group, its low
density environment likely plays a role in the formation and retention of the
giant LSB and HI disks. We model the spectral energy distributions and find
that the LSB disk is likely older than the lenticular component. UGC1382 has
UV-optical colors typical of galaxies transitioning through the green valley.
Within the LSB disk are spiral arms forming stars at extremely low
efficiencies. The gas depletion time scale of ~10^11 yr suggests that UGC1382
may be a very long term resident of the green valley. We find that the
formation and evolution of the LSB disk is best explained by the accretion of
gas-rich LSB dwarf galaxies.


title:
Natal Kicks and Time Delays in Merging Neutron Star Binaries -
  Implications for r-process nucleosynthesis in Ultra Faint Dwarfs and in the
  Milky Way

abstract:
  Merging neutron star binaries are prime candidate sources for heavy r-process
nucleosynthesis. The amount of heavy r-process material is consistent with the
mass ejection and rates of mergers, and abundances of relic radioactive
materials suggest that heavy r-process material is produced in rare events.
Observations of possible macronovae provide further support for this model.
Still, some concerns remain. One is the observation of heavy r-process elements
in Ultra Faint Dwarf (UFD) galaxies. The escape velocities from UFDs are so
small that the natal kicks, taking place at neutron stars birth, might eject
such binaries from UFDs. Furthermore the old stellar populations of UFDs
requires that r-process nucleosynthesis must have taken place very early on,
while it may take several Gyr for compact binaries to merge. This last problem
arises also within the Milky Way where heavy r-process materials has been
observed in some low metallicity stars. We show here that since a significant
fraction of neutron star binaries form with a very small proper motion those
won't be ejected even from a UFD. Furthermore, a significant fraction of these
binaries merge within a few hundred Myr and in some cases the merger time is
even shorter than a hundred Myr. This population of "rapid mergers" explains
the appearance of heavy r-process material in both UFDs and in the Milky Way.


title: Nuclear Zemach Moments and Finite-Size Corrections to Allowed Beta Decay

abstract:
  The finite-size correction to $\beta$-decay plays an important role in
determining the expected antineutrino spectra from reactors at a level that is
important for the reactor-neutrino anomaly. Here we express the leading-order
finite-size correction to allowed $\beta$-decay in terms of Zemach moments. We
calculate the Zemach moments within a Hartree-Fock model using a Skyrme-like
energy density functional. We find that the Zemach moments are increased
relative to predictions based on the simple assumption of identical uniform
nuclear-charge and weak-transition densities. However, for allowed ground-state
to ground-state transitions in medium and heavy nuclei, the detailed nuclear
structure calculations do not change the finite-size corrections significantly
from the simple model predictions, and are only 10-15% larger than the latter
even though the densities differ significantly.


title: Foreground Bias From Parametric Models of Far-IR Dust Emission

abstract:
  We use simple toy models of far-IR dust emission to estimate the accuracy to
which the polarization of the cosmic microwave background can be recovered
using multi-frequency fits, if the parametric form chosen for the fitted dust
model differs from the actual dust emission. Commonly used approximations to
the far-IR dust spectrum yield CMB residuals comparable to or larger than the
sensitivities expected for the next generation of CMB missions, despite fitting
the combined CMB + foreground emission to precision 0.1% or better. The
Rayleigh-Jeans approximation to the dust spectrum biases the fitted dust
spectral index by Delta beta_d = 0.2 and the inflationary B-mode amplitude by
Delta r = 0.03. Fitting the dust to a modified blackbody at a single
temperature biases the best-fit CMB by Delta r > 0.003 if the true dust
spectrum contains multiple temperature components. A 13-parameter model fitting
two temperature components reduces this bias by an order of magnitude if the
true dust spectrum is in fact a simple superposition of emission at different
temperatures, but fails at the level Delta r = 0.006 for dust whose spectral
index varies with frequency. Restricting the observing frequencies to a narrow
region near the foreground minimum reduces these biases for some dust spectra
but can increase the bias for others. Data at THz frequencies surrounding the
peak of the dust emission can mitigate these biases while providing a direct
determination of the dust temperature profile.


title:
The Romulus Cosmological Simulations: A Physical Approach to the
  Formation, Dynamics and Accretion Models of SMBHs

abstract:
  We present a novel implementation of supermassive black hole (SMBH)
formation, dynamics, and accretion in the massively parallel tree+SPH code,
ChaNGa. This approach improves the modeling of SMBHs in fully cosmological
simulations, allowing for a more de- tailed analysis of SMBH-galaxy
co-evolution throughout cosmic time. Our scheme includes novel, physically
motivated models for SMBH formation, dynamics and sinking timescales within
galaxies, and SMBH accretion of rotationally supported gas. The sub-grid
parameters that regulate star formation (SF) and feedback from SMBHs and SNe
are optimized against a comprehensive set of z = 0 galaxy scaling relations
using a novel, multi-dimensional parameter search. We have incorporated our new
SMBH implementation and parameter optimization into a new set of high
resolution, large-scale cosmological simulations called Romulus. We present
initial results from our flagship simulation, Romulus25, showing that our SMBH
model results in SF efficiency, SMBH masses, and global SF and SMBH accretion
histories at high redshift that are consistent with observations. We discuss
the importance of SMBH physics in shaping the evolution of massive galaxies and
show how SMBH feedback is much more effective at regulating star formation
compared to SNe feedback in this regime. Further, we show how each aspect of
our SMBH model impacts this evolution compared to more common approaches.
Finally, we present a science application of this scheme studying the
properties and time evolution of an example dual AGN system, highlighting how
our approach allows simulations to better study galaxy interactions and SMBH
mergers in the context of galaxy-BH co-evolution.


title:
Capabilities of long-baseline experiments in the presence of a sterile
  neutrino

abstract:
  Assuming that there is a sterile neutrino, we ask what then is the ability of
long-baseline experiments to i) establish that neutrino oscillation violates
CP, ii) determine the three-neutrino mass ordering, and iii) determine which
CP-violating phase or phases are the cause of any CP violation that may be
observed. We find that the ability to establish CP violation and to determine
the mass ordering could be very substantial. However, the effects of the
sterile neutrino could be quite large, and it might prove very difficult to
determine which phase is responsible for an observed CP violation. We explain
why a sterile neutrino changes the long-baseline sensitivities to CP violation
and to the mass ordering in the ways that it does. We note that long-baseline
experiments can probe the presence of sterile neutrinos in a way that is
different from, and complementary to, the probes of short-baseline experiments.
We explore the question of how large sterile-active mixing angles need to be
before long-baseline experiments can detect their effects, or how small they
need to be before the interpretation of these experiments can safely disregard
the possible existence of sterile neutrinos.


title: Small-$x$ resummation from HELL

abstract:
  Small-$x$ logarithmic enhancements arising from high-energy gluon emissions
affect both the evolution of collinearly-factorized parton densities and
partonic coefficient functions. With the higher collider energy reached by the
LHC, the prospect of a future high-energy collider, and the recent
deep-inelastic scattering (DIS) results at small-$x$ from HERA, providing
phenomenological tools for performing small-$x$ resummation has become of great
relevance. In this paper we discuss a framework to perform small-$x$
resummation for both parton evolution and partonic coefficient functions and we
describe its implementation in a computer code named High-Energy Large
Logarithms (HELL). We present resummed and matched results for the DGLAP
splitting functions and, as a proof of principle, for the massless structure
functions in DIS.


title: Degenerate Higgs bosons: hiding a second Higgs at 125 GeV

abstract:
  More than one Higgs boson may be present near the currently discovered Higgs
mass, which can not be properly resolved due to the limitations in the
intrinsic energy resolution at the Large Hadron Collider. We investigated the
scenarios where two $CP$-even Higgs bosons are degenerate in mass. To correctly
predict the Higgs signatures, quantum interference effects between the two
Higgs bosons must be taken into account, which, however, has been often
neglected in the literature. We carried out a global analysis including the
interference effects for a variety of Higgs searching channels at the Large
Hadron Collider, which suggests that the existence of two degenerate Higgs
bosons near 125 GeV is highly likely. Prospects of distinguishing the
degenerate Higgs case from the single Higgs case are discussed.


title:
Radiative Processes in Graphene and Similar Nanostructures at Strong
  Electric Fields

abstract:
  Low-energy single-electron dynamics in graphene monolayers and similar
nanostructures is described by the Dirac model, being a 2+1 dimensional version
of massless QED with the speed of light replaced by the Fermi velocity
v_{F}=c/300. Methods of strong-field QFT are relevant for the Dirac model,
since any low-frequency electric field requires a nonperturbative treatment of
massless carriers in case it remains unchanged for a sufficiently long time
interval. In this case, the effects of creation and annihilation of
electron-hole pairs produced from vacuum by a slowly varying and small-gradient
electric field are relevant, thereby substantially affecting the radiation
pattern. For this reason, the standard QED text-book theory of photon emission
cannot be of help. We construct the Fock-space representation of the Dirac
model, which takes exact accounts of the effects of vacuum instability caused
by external electric fields, and in which the interaction between electrons and
photons is taken into account perturbatively, following the general theory (the
generalized Furry representation). We consider the effective theory of photon
emission in the first-order approximation and construct the corresponding total
probabilities, taking into account the unitarity relation.


title:
Gate-controllable magneto-optic Kerr effect in layered collinear
  antiferromagnets

abstract:
  Using symmetry arguments and a tight-binding model, we show that for layered
collinear anti- ferromagnets, magneto-optic effects can be generated and
manipulated by controlling crystal symmetries through a gate voltage. This
provides a promising route for electric field manipulation of the magneto-optic
effects without modifying the underlying magnetic structure. We further
demonstrate the gate control of magneto-optic Kerr effect (MOKE) in bilayer
MnPSe3 using first-principles calculations. The field-induced inversion
symmetry breaking effect leads to gate-controllable MOKE whose direction of
rotation can be switched by the reversal of the gate voltage.


title: Manipulating matter waves in an optical superlattice

abstract:
  We investigate the potential for controlling a non-interacting Bose-Einstein
condensate loaded into a one-dimensional optical superlattice. Our control
strategy combines Bloch oscillations originating from accelerating the lattice
and from time-dependent control of the superlattice parameters. We investigate
two experimentally viable scenarios, very low and very high potential depths.
We are able to exhibit a wide range of control over energy band populations
using the superlattice control parameters. With this analysis we consider
several examples of quantum state preparation in the superlattice structure
that may be difficult to achieve in a regular lattice.


title: The Dilaton-like Higgs boson with scalar singlet dark matter

abstract:
  We study a model with a Higgs-like dilaton and a Standard Model gauge-singlet
scalar dark matter candidate. We begin by updating the status of identifying
the observed 125 GeV Higgs-like boson with the pseudo Nambu-Goldstone boson
that arises from the spontaneous breaking of scale invariance using recent
Higgs boson signal strength measurements by the ATLAS and CMS collaborations.
We then constrain the extended model with recent constraints on the Higgs
invisible width, the observed dark matter relic abundance and the latest dark
matter direct detection limits. We found that the magnitude of the
dilaton-$\gamma\gamma$ and dilaton-glue-glue coupling is constrained to be
close to the standard model values. The mass of the dark matter candidate is
contrained to be greater than half the dilaton mass by relic abundance limits
and Higgs invisible width limits. Dark matter direct detection limits allow
only small mass regions which will be further constrained by upcoming DEAP
measurements.


title: Fault-Tolerant Quantum Error Correction for non-Abelian Anyons

abstract:
  While topological quantum computation is intrinsically fault-tolerant at zero
temperature, it loses its topological protection at any finite temperature. We
present a scheme to protect the information stored in a system supporting
non-cyclic anyons against thermal and measurement errors. The correction
procedure builds on the work of G\'acs [Gacs 1986] and Harrington [Harrington
2004] and operates as a local cellular automaton. In contrast to previously
studied schemes, our scheme is valid for both abelian and non-abelian anyons
and accounts for measurement errors. We analytically prove the existence of a
fault-tolerant threshold for a certain class of non-Abelian anyon models, and
numerically simulate the procedure for the specific example of Ising anyons.
The result of our simulations are consistent with a threshold between $10^{-4}$
and $10^{-3}$.


title:
Nonthermal Fixed Points in Quantum Field Theory Beyond the Weak-Coupling
  Limit

abstract:
  Quantum systems in extreme conditions can exhibit universal behavior far from
equilibrium associated to nonthermal fixed points with a wide range of topical
applications from early-universe inflaton dynamics and heavy-ion collisions to
strong quenches in ultracold quantum gases. So far, most studies have relied on
a mapping of the quantum dynamics onto a classical-statistical theory that can
be simulated on a computer. However, the mapping is based on a weak-coupling
limit, while phenomenological applications often require moderate interaction
strengths. We report on the observation of nonthermal fixed points directly in
quantum field theory beyond the weak-coupling limit. For the example of a
relativistic scalar O(N)-symmetric quantum field theory, we numerically solve
the nonequilibrium dynamics employing a 1/N expansion to next-to-leading order,
which does not rely on a small coupling parameter. Starting from two different
sets of overoccupied and of strong-field initial conditions, we find that
nonthermal fixed points are not restricted to parameter ranges suitable for
classical-statistical simulations, but extend also to couplings of order one.
While the infrared behavior is found to be insensitive to the differences in
the initial conditions, we demonstrate that transport phenomena to higher
momenta depend on the presence or absence of a symmetry-breaking field
expectation value.


title:
Unconditionally $p$-converging operators and Dunford-Pettis Property of
  order $p$

abstract:
  In the present paper we study unconditionally $p$-converging operators and
Dunford-Pettis property of order $p$. New characterizations of unconditionally
$p$-converging operators and Dunford-Pettis property of order $p$ are
established. Six quantities are defined to measure how far an operator is from
being unconditionally $p$-converging. We prove quantitative versions of
relationships of completely continuous operators,unconditionally $p$-converging
operators and unconditionally converging operators. We further investigate
possible quantifications of the Dunford-Pettis property of order $p$.


title: Metal hydrogen sulfide critical temperature at the pressure 225 gpa

abstract:
  \'Eliashberg theory, being generalized to the electron-phonon (EP) systems
with not constant density of electronic states, as well as to the frequency
behavior of the renormalization of both the electron mass and the chemical
potential, is used to study hydrogen sulphide phase under pressure. The phonon
contribution to the anomalous electron Green's function (GF) is considered. The
pairing is considered within the overall width of the electron band, and not
only in a narrow layer at the Fermi surface. The frequency and the temperature
dependences of the electron mass renormalization ReZ , the density of
electronic states , renormalized by the EP interaction , the spectral function
of the electron-phonon interaction, obtained by calculation are used to
calculate the electronic abnormal GF. The \'Eliashberg generalized equations
with the variable density of electronic states are resolved. The dependence of
both the real and the imaginary part of the order parameter on the frequency in
the phase is obtained. The value in the hydrogen sulfide phase at the pressure
P = 225 GPa has been defined.


title:
Pe{\l}czy\'{n}ski's property ($V^{*}$) of order $p$ and its
  quantification

abstract:
  We introduce the concepts of Pe{\l}czy\'{n}ski's property ($V$) of order $p$
and Pe{\l}czy\'{n}ski's property ($V^{*}$) of order $p$. It is proved that, for
each $1<p<\infty$, the James $p$-space $J_{p}$ enjoys Pe{\l}czy\'{n}ski's
property ($V^{*}$) of order $p$ and the James $p^{*}$-space $J_{p^{*}}$ (where
$p^{*}$ denotes the conjugate number of $p$) enjoys Pe{\l}czy\'{n}ski's
property ($V$) of order $p$. We prove that both $L_{1}(\mu)$ ($\mu$ a finite
positive measure) and $l_{1}$ enjoy the quantitative version of
Pe{\l}czy\'{n}ski's property ($V^{*}$).


title: Modeling mutations in bacteria and human tissues

abstract:
  This thesis is aimed at studying mutations, understood as trajectories in the
DNA configuration space. An evolutive model of mutations in terms of Levy
flights is proposed. The parameters of the model are estimated by means of data
from the Long-Term Evolution Experiment (LTEE) with {\it E. Coli} bacteria. The
results of simulations on competition of clones, mean fitness, etc are compared
with experimental data. We discuss the qualitative analogy found between the
bacterial mutator phenotype and the cancerous cells. The role of radiation as
source of mutations is analyzed. We focus on the case of Radon's decay in the
lungs in breathing.


title:
A "Rule of Five" Framework for Models and Modeling to Unify
  Mathematicians and Biologists and Improve Student Learning

abstract:
  Despite widespread calls for the incorporation of mathematical modeling into
the undergraduate biology curriculum, there is lack of a common understanding
around the definition of modeling, which inhibits progress. In this paper, we
extend the "Rule of Four," initially used in calculus reform efforts, to a
framework for models and modeling that is inclusive of varying disciplinary
definitions of each. This unifying framework allows us to both build on
strengths that each discipline and its students bring, but also identify gaps
in modeling activities practiced by each discipline. We also discuss benefits
to student learning and interdisciplinary collaboration.


title: Passive Power Filters

abstract:
  Power converters require passive low-pass filters which are capable of
reducing voltage ripples effectively. In contrast to signal filters, the
components of power filters must carry large currents or withstand large
voltages, respectively. In this paper, three different suitable filter
structures for d.c./d.c. power converters with inductive load are introduced.
The formulas needed to calculate the filter components are derived step by step
and practical examples are given. The behaviour of the three discussed filters
is compared by means of the examples. Practical aspects for the realization of
power filters are also discussed.


title:
Magnetosphere Magnetic Field Wobble Effects on the Dynamics of the
  Jovian Magnetosphere

abstract:
  The Jovian magnetosphere is complicated by the multiple plasma sources and
ion species present within it, as well as fast rotation with its dipole axis
titled from its rotational axis. To date global models of Jovian have neglected
the presence of the different ion species as well as the tilted nature of the
dipole axis. This paper reports the results of the first multi-fluid global
modeling of these effects in a single self-consistent study for processes
occurring in the outer magnetosphere. In the inner magnetosphere the model
densities are shown to be comparable to observed densities with much of the
density variables due to the wobble. The wobble enables plasma to be
transported to higher latitudes and then centrifugal acceleration leads to
radial transport of the plasma. At the interface between the middle and outer
magnetosphere, the wobble produces a sinusoidal modulation of the plasma
properties, which yields at a fixed observing point two density peaks, each
with the planetary period. However, because of solar wind forcing and the fast
rotation of Jupiter, torques are exerted on the outer magnetospheric plasma
such that the azimuthal speed between the southern and northern hemispheres are
unequal. This leads to the asymmetric square wave modulation of the plasma
properties in the outer magnetosphere such that only one density peak is seen
each planetary period in the outer magnetosphere. This differential speed leads
to reconnection in the tail at the planetary period and enhanced ejection of
plasma down the tail at the planetary period. These processes could explain the
periodicity seen in the New Horizons' data without the need for invoking
arbitrary solar wind conditions. The energetic particles generated by these
processes are shown to map to the arc-like structures seen in the dusk side
auroral features.


title: Discovering Boolean Gates in Slime Mould

abstract:
  Slime mould of Physarum polycephalum is a large cell exhibiting rich spatial
non-linear electrical characteristics. We exploit the electrical properties of
the slime mould to implement logic gates using a flexible hardware platform
designed for investigating the electrical properties of a substrate (MECOBO).
We apply arbitrary electrical signals to `configure' the slime mould, i.e.
change shape of its body and, measure the slime mould's electrical response. We
show that it is possible to find configurations that allow the Physarum to act
as any 2-input Boolean gate. The occurrence frequency of the gates discovered
in the slime was analysed and compared to complexity hierarchies of logical
gates obtained in other unconventional materials. The search for gates was
performed by both sweeping across configurations in the real material as well
as training a neural network-based model and searching the gates therein using
gradient descent.


title: $B$ and $B_s$ Meson Spectroscopy

abstract:
  Properties of bottom and bottom-strange mesons are computed in two
relativized quark models. Model masses and wavefunctions are used to predict
radiative transition rates and the $^3P_0$ quark pair creation model is used to
compute strong decay widths. A comparison to recently observed bottom and
bottom-strange states is made. We find that there are numerous excited $B$ and
$B_s$ mesons that have relatively narrow widths and significant branching
ratios to simple final states such as $B\pi$, $B^*\pi$, $BK$, and $B^*K$ that
could be observed in the near future.


title: Free groups and quasidiagonality

abstract:
  We use free groups to settle a couple questions about the values of the
Pimsner-Popa-Voiculescu modulus of quasidiagonality for a set of operators
$\Omega$, denoted by qd$(\Omega)$. Along the way we deduce information about
the operator space structure of finite dimensional subspaces of
$\mathbb{C}[\mathbb{F}_d]\subseteq C^*_{\ell^p}(\mathbb{F}_d)$ where
$C^*_{\ell^p}(\mathbb{F}_d)$ is the so-called $\ell^p$-completion of
$\mathbb{C}[\mathbb{F}_d].$ Roughly speaking, we use free groups and
qd$(\Omega)$ to put a quantitative face on the two known qualitative
obstructions to quasidiagonality; absence of an amenable trace or the presence
of a proper isometry. The modulus of quasidiagonality for a proper isometry is
equal to 1. We show that qd$(\{\lambda_a,\lambda_b\})\in [1/2,\sqrt{3}/2]$
where $a$ and $b$ are free group generators and $\lambda$ is the left regular
representation. In another direction, we use certain $\ell^p$ representations
of free groups constructed by Pytlik and Szwarc and a recent result of Ruan and
Wiersma to show that qd$(\Omega)$ may be positive, yet arbitrarily close to
zero when $\Omega$ is a set of unitaries.


title: Argumentation Models for Cyber Attribution

abstract:
  A major challenge in cyber-threat analysis is combining information from
different sources to find the person or the group responsible for the
cyber-attack. It is one of the most important technical and policy challenges
in cyber-security. The lack of ground truth for an individual responsible for
an attack has limited previous studies. In this paper, we take a first step
towards overcoming this limitation by building a dataset from the
capture-the-flag event held at DEFCON, and propose an argumentation model based
on a formal reasoning framework called DeLP (Defeasible Logic Programming)
designed to aid an analyst in attributing a cyber-attack. We build models from
latent variables to reduce the search space of culprits (attackers), and show
that this reduction significantly improves the performance of
classification-based approaches from 37% to 62% in identifying the attacker.


title: Opers versus nonabelian Hodge

abstract:
  For a complex simple simply connected Lie group $G$, and a compact Riemann
surface $C$, we consider two sorts of families of flat $G$-connections over
$C$. Each family is determined by a point ${\mathbf u}$ of the base of
Hitchin's integrable system for $(G,C)$. One family $\nabla_{\hbar,{\mathbf
u}}$ consists of $G$-opers, and depends on $\hbar \in {\mathbb C}^\times$. The
other family $\nabla_{R,\zeta,{\mathbf u}}$ is built from solutions of
Hitchin's equations, and depends on $\zeta \in {\mathbb C}^\times, R \in
{\mathbb R}^+$. We show that in the scaling limit $R \to 0$, $\zeta = \hbar R$,
we have $\nabla_{R,\zeta,{\mathbf u}} \to \nabla_{\hbar,{\mathbf u}}$. This
establishes and generalizes a conjecture formulated by Gaiotto.


title: Single-Channel Multi-Speaker Separation using Deep Clustering

abstract:
  Deep clustering is a recently introduced deep learning architecture that uses
discriminatively trained embeddings as the basis for clustering. It was
recently applied to spectrogram segmentation, resulting in impressive results
on speaker-independent multi-speaker separation. In this paper we extend the
baseline system with an end-to-end signal approximation objective that greatly
improves performance on a challenging speech separation. We first significantly
improve upon the baseline system performance by incorporating better
regularization, larger temporal context, and a deeper architecture, culminating
in an overall improvement in signal to distortion ratio (SDR) of 10.3 dB
compared to the baseline of 6.0 dB for two-speaker separation, as well as a 7.1
dB SDR improvement for three-speaker separation. We then extend the model to
incorporate an enhancement layer to refine the signal estimates, and perform
end-to-end training through both the clustering and enhancement stages to
maximize signal fidelity. We evaluate the results using automatic speech
recognition. The new signal approximation objective, combined with end-to-end
training, produces unprecedented performance, reducing the word error rate
(WER) from 89.1% down to 30.8%. This represents a major advancement towards
solving the cocktail party problem.


title:
Toward a Robust Crowd-labeling Framework using Expert Evaluation and
  Pairwise Comparison

abstract:
  Crowd-labeling emerged from the need to label large-scale and complex data, a
tedious, expensive, and time-consuming task. One of the main challenges in the
crowd-labeling task is to control for or determine in advance the proportion of
low-quality/malicious labelers. If that proportion grows too high, there is
often a phase transition leading to a steep, non-linear drop in labeling
accuracy as noted by Karger et al. [2014]. To address these challenges, we
propose a new framework called Expert Label Injected Crowd Estimation (ELICE)
and extend it to different versions and variants that delay phase transition
leading to a better labeling accuracy. ELICE automatically combines and boosts
bulk crowd labels supported by labels from experts for limited number of
instances from the dataset. The expert-labels help to estimate the individual
ability of crowd labelers and difficulty of each instance, both of which are
used to aggregate the labels. Empirical evaluation shows the superiority of
ELICE as compared to other state-of-the-art methods. We also derive a lower
bound on the number of expert-labeled instances needed to estimate the crowd
ability and dataset difficulty as well as to get better quality labels.


title:
Interaction patterns and individual dynamics shape the way we move in
  synchrony

abstract:
  An important open problem in Human Behaviour is to understand how
coordination emerges in human ensembles. This problem has been seldom studied
quantitatively in the existing literature, in contrast to situations involving
dual interaction. Here we study motor coordination (or synchronisation) in a
group of individuals where participants are asked to visually coordinate an
oscillatory hand motion. We separately tested two groups of seven participants.
We observed that the coordination level of the ensemble depends on group
homogeneity, as well as on the pattern of visual couplings (who looked at
whom). Despite the complexity of social interactions, we show that networks of
coupled heterogeneous oscillators with different structures capture well the
group dynamics. Our findings are relevant to any activity requiring the
coordination of several people, as in music, sport or at work, and can be
extended to account for other perceptual forms of interaction such as sound or
feel.


title:
Density bump formation in a collisionless electrostatic shock wave in a
  laser-ablated plasma

abstract:
  The emergence of a density bump at the front of a collisionless electrostatic
shock wave have been observed experimentally during the ablation of an
aluminium foil by a femtosecond laser pulse. We have performed numerical
simulations of the dynamics of this phenomena developing alongside the
generation of a package of ion-acoustic waves, exposed to a continual flow of
energetic electrons, in a collisionless plasma. We present the physical
interpretation of the observed effects and show that the bump consists of
transit particles, namely, the accelerated ions from the dense plasma layer,
and the ions from the diluted background plasma, formed by a nanosecond laser
prepulse during the ablation.


title: Applying Deep Learning to the Newsvendor Problem

abstract:
  The newsvendor problem is one of the most basic and widely applied inventory
models. There are numerous extensions of this problem. If the probability
distribution of the demand is known, the problem can be solved analytically.
  However, approximating the probability distribution is not easy and is prone
to error; therefore, the resulting solution to the newsvendor problem may be
not optimal. To address this issue, we propose an algorithm based on deep
learning that optimizes the order quantities for all products based on features
of the demand data. Our algorithm integrates the forecasting and
inventory-optimization steps, rather than solving them separately, as is
typically done, and does not require knowledge of the probability distributions
of the demand. Numerical experiments on real-world data suggest that our
algorithm outperforms other approaches, including data-driven and machine
learning approaches, especially for demands with high volatility. Finally, in
order to show how this approach can be used for other inventory optimization
problems, we provide an extension for (r,Q) policies.


title:
Evidence of a fractional quantum Hall nematic phase in a microscopic
  model

abstract:
  At small momenta, the Girvin-MacDonald-Platzman (GMP) mode in the fractional
quantum Hall (FQH) effect can be identified with gapped nematic fluctuations in
the isotropic FQH liquid. This correspondence would be exact as the GMP mode
softens upon approach to the putative point of a quantum phase transition to a
FQH nematic. Motivated by these considerations as well as by suggestive
evidence of an FQH nematic in tilted field experiments, we have sought evidence
of such a nematic FQHE in a microscopic model of interacting electrons in the
lowest Landau level at filling factor 1/3. Using a family of anisotropic
Laughlin states as trial wave functions, we find a continuous quantum phase
transition between the isotropic Laughlin liquid and the FQH nematic. Results
of numerical exact diagonalization also suggest that rotational symmetry is
spontaneously broken, and that the phase diagram of the model contains both a
nematic and a stripe phase.


title:
Probabilistic Cooperation of a Full-Duplex Relay in Random Access
  Networks

abstract:
  In this work, we analyze the probabilistic cooperation of a full-duplex relay
in a multiuser random-access network. The relay is equipped with on/off modes
for the receiver and the transmitter independently. These modes are modeled as
probabilities by which the receiver and the transmitter are activated. We
provide analytical expressions for the performance of the relay queue, such as
arrival and service rates, stability conditions, and the average queue size. We
optimize the relay's operation setup to maximize the network-wide throughput
while, simultaneously, we keep the relay's queue stable and minimize the
consumed energy. Furthermore, we study the effect of the SINR threshold and the
self-interference (SI) coefficient on the per-user and network-wide throughput.
For low SINR threshold, we show under which circumstances it is beneficial to
switch off the relay completely, or switch off the relay's receiver only.


title:
Minimal cover of high-dimensional chaotic attractors by embedded
  coherent structures

abstract:
  We propose a general method for constructing a minimal cover of
high-dimensional chaotic attractors by embedded coherent structures, such as
(but not limited to) periodic orbits. By minimal cover we mean a subset of
available coherent structures such that the approximation of chaotic dynamics
by a minimal cover with a predefined proximity threshold is as good as the
approximation by the full available set. The proximity measure can be chosen
with considerable freedom and adapted to the properties of any given chaotic
system. In the context of a Kuramoto-Sivashinsky chaotic attractor, we
demonstrate that the minimal cover can be faithfully constructed even when the
proximity measure is defined within a subspace of dimension much smaller than
the dimension of space containing the attractor. We discuss how the minimal
cover can be used to provide a reduced description of the attractor structure
and the dynamics on it.


title:
Tunable Ultrafast Thermal Relaxation in Graphene Measured by
  Continuous-Wave Photomixing

abstract:
  Hot electron effects in graphene are significant because of graphene's small
electronic heat capacity and weak electron-phonon coupling, yet the dynamics
and cooling mechanisms of hot electrons in graphene are not completely
understood. We describe a novel photocurrent spectroscopy method that uses the
mixing of continuous-wave lasers in a graphene photothermal detector to measure
the frequency dependence and nonlinearity of hot-electron cooling in graphene
as a function of the carrier concentration and temperature. The method offers
unparalleled sensitivity to the nonlinearity, and probes the ultrafast cooling
of hot carriers with an optical fluence that is orders of magnitude smaller
than in conventional time-domain methods, allowing for accurate
characterization of electron-phonon cooling near charge neutrality. Our
measurements reveal that near the charge neutral-point the nonlinear power
dependence of the electron cooling is dominated by disorder-assisted
collisions, while at higher carrier concentrations conventional
momentum-conserving cooling prevails in the nonlinear dependence. The relative
contribution of these competing mechanisms can be electrostatically tuned
through the application of a gate voltage -- an effect that is unique to
graphene.


title: Mixing times of critical 2D Potts models

abstract:
  We study dynamical aspects of the $q$-state Potts model on an $n\times n$ box
at its critical $\beta_c(q)$. Heat-bath Glauber dynamics and cluster dynamics
such as Swendsen--Wang (that circumvent low-temperature bottlenecks) are all
expected to undergo "critical slowdowns" in the presence of periodic boundary
conditions: the inverse spectral gap, which in the subcritical regime is
$O(1)$, should at criticality be polynomial in $n$ for $1< q \leq 4$, and
exponential in $n$ for $q>4$ in accordance with the predicted discontinuous
phase transition. This was confirmed for $q=2$ (the Ising model) by the second
author and Sly, and for sufficiently large $q$ by Borgs et al.
  Here we show that the following holds for the critical Potts model on the
torus: for $q=3$, the inverse gap of Glauber dynamics is $n^{O(1)}$; for $q=4$,
it is at most $n^{O(\log n)}$; and for every $q>4$ in the phase-coexistence
regime, the inverse gaps of both Glauber dynamics and Swendsen--Wang dynamics
are exponential in $n$.
  For free or monochromatic boundary conditions and large $q$, we show that the
dynamics at criticality is faster than on the torus (unlike the Ising model
where free/periodic boundary conditions induce similar dynamical behavior at
all temperatures): the inverse gap of Swendsen--Wang dynamics is
$\exp(n^{o(1)})$.


title: Relativistic electrons produced by foreshock disturbances

abstract:
  Foreshock disturbances -- large-scale (~1000 km to >30,000 km), transient
(~5-10 per day - lasting ~10s of seconds to several minutes) structures [1,2] -
generated by suprathermal (>100 eV to 100s of keV) ions [3,4] arise upstream of
Earth's bow shock formed by the solar wind colliding with the Earth's
magnetosphere. They have recently been found to accelerate ions to energies of
several keV [5,6]. Although electrons in Saturn's high Mach number (M > 40) bow
shock can be accelerated to relativistic energies (nearly 1000 keV) [7], it has
hitherto been thought impossible to accelerate electrons at the much weaker (M
< 20) Earth's bow shock beyond a few 10s of keV [8]. Here we report
observations of electrons energized by foreshock disturbances to energies up to
at least ~300 keV. Although such energetic electrons have been previously
reported, their presence has been attributed to escaping magnetospheric
particles [9,10] or solar events [11]. These relativistic electrons are not
associated with any solar activity nor are they of magnetospheric origin.
Further, current theories of ion acceleration in foreshock disturbances cannot
account for electrons accelerated to the observed relativistic energies
[12-17]. These electrons are clearly coming from the disturbances, leaving us
with no explanation as to their origin.


title: Maximizing the Sum of Radii of Disjoint Balls or Disks

abstract:
  Finding nonoverlapping balls with given centers in any metric space,
maximizing the sum of radii of the balls, can be expressed as a linear program.
Its dual linear program expresses the problem of finding a minimum-weight set
of cycles (allowing 2-cycles) covering all vertices in a complete geometric
graph. For points in a Euclidean space of any finite dimension~$d$, with any
convex distance function on this space, this graph can be replaced by a sparse
subgraph obeying a separator theorem. This graph structure leads to an
algorithm for finding the optimum set of balls in time $O(n^{2-1/d})$,
improving the $O(n^3)$ time of a naive cycle cover algorithm. As a subroutine,
we provide an algorithm for weighted bipartite matching in graphs with
separators, which speeds up the best previous algorithm for this problem on
planar bipartite graphs from $O(n^{3/2}\log n)$ to $O(n^{3/2})$ time. We also
show how to constrain the balls to all have radius at least a given threshold
value, and how to apply our radius-sum optimization algorithms to the problem
of embedding a finite metric space into a star metric minimizing the average
distance to the hub.