title: Minimal inflationary cosmologies and constraints on reheating

abstract:
  With the growing consensus on simple power law inflation models not being
favored by the PLANCK observation, dynamics for the non-standard form of the
inflaton potential gain significant interest in the recent past. In this paper,
we analyze in great detail classes of phenomenologically motivated inflationary
models with non-polynomial potential which are the generalization of the
potential introduced in \cite{mhiggs}. After the end of inflation, inflaton
field will coherently oscillate around its minimum. Depending upon the initial
amplitude of the oscillation and coupling parameters standard parametric
resonance phenomena will occur. Therefore, we will study how the inflationary
model parameters play an important role in understanding the resonant structure
of our model under study. Subsequently, the universe will go through the
perturbative reheating phase. However, without any specific model
consideration, we further study the constraints on our models based on model
independent reheating constraint analysis.


title: Tuning the Photon Statistics of a Strongly Coupled Nanophotonic System

abstract:
  We investigate the dynamics of single- and multi-photon emission from detuned
strongly coupled systems based on the quantum-dot-photonic-crystal resonator
platform. Transmitting light through such systems can generate a range of
non-classical states of light with tunable photon counting statistics due to
the nonlinear ladder of hybridized light-matter states. By controlling the
detuning between emitter and resonator, the transmission can be tuned to
strongly enhance either single- or two-photon emission processes. Despite the
strongly-dissipative nature of these systems, we find that by utilizing a
self-homodyne interference technique combined with frequency-filtering we are
able to find a strong two-photon component of the emission in the multi-photon
regime. In order to explain our correlation measurements, we propose rate
equation models that capture the dominant processes of emission both in the
single- and multi-photon regimes. These models are then supported by
quantum-optical simulations that fully capture the frequency filtering of
emission from our solid-state system.


title: Near-Infrared Image Dehazing Via Color Regularization

abstract:
  Near-infrared imaging can capture haze-free near-infrared gray images and
visible color images, according to physical scattering models, e.g., Rayleigh
or Mie models. However, there exist serious discrepancies in brightness and
image structures between the near-infrared gray images and the visible color
images. The direct use of the near-infrared gray images brings about another
color distortion problem in the dehazed images. Therefore, the color distortion
should also be considered for near-infrared dehazing. To reflect this point,
this paper presents an approach of adding a new color regularization to
conventional dehazing framework. The proposed color regularization can model
the color prior for unknown haze-free images from two captured images. Thus,
natural-looking colors and fine details can be induced on the dehazed images.
The experimental results show that the proposed color regularization model can
help remove the color distortion and the haze at the same time. Also, the
effectiveness of the proposed color regularization is verified by comparing
with other conventional regularizations. It is also shown that the proposed
color regularization can remove the edge artifacts which arise from the use of
the conventional dark prior model.


title: The symbolic defect of an ideal

abstract:
  Let $I$ be a homogeneous ideal of $\Bbbk[x_0,\ldots,x_n]$. To compare
$I^{(m)}$, the $m$-th symbolic power of $I$, with $I^m$, the regular $m$-th
power, we introduce the $m$-th symbolic defect of $I$, denoted
$\operatorname{sdefect}(I,m)$. Precisely, $\operatorname{sdefect}(I,m)$ is the
minimal number of generators of the $R$-module $I^{(m)}/I^m$, or equivalently,
the minimal number of generators one must add to $I^m$ to make $I^{(m)}$. In
this paper, we take the first step towards understanding the symbolic defect by
considering the case that $I$ is either the defining ideal of a star
configuration or the ideal associated to a finite set of points in
$\mathbb{P}^2$. We are specifically interested in identifying ideals $I$ with
$\operatorname{sdefect}(I,2) = 1$.


title:
Implications for (d,p) reaction theory from nonlocal dispersive optical
  model analysis of $^{40}$Ca(d,p)$^{41}$Ca

abstract:
  The nonlocal dispersive optical model (NLDOM) nucleon potentials are used for
the first time in the adiabatic analysis of a (d,p) reaction to generate
distorted waves both in the entrance and exit channels. These potentials were
designed and fitted by Mahzoon $et \text{ } al.$ [Phys. Rev. Lett. 112, 162502
(2014)] to constrain relevant single-particle physics in a consistent way by
imposing the fundamental properties, such as nonlocality, energy-dependence and
dispersive relations, that follow from the complex nature of nuclei. However,
the NLDOM prediction for the $^{40}$Ca(d,p)$^{41}$Ca cross sections at low
energy, typical for some modern radioactive beam ISOL facilities, is about
70$\%$ higher than the experimental data despite being reduced by the NLDOM
spectroscopic factor of 0.73. This overestimation comes most likely either from
insufficient absorption or due to constructive interference between ingoing and
outgoing waves. This indicates strongly that additional physics arising from
many-body effects is missing in the widely used current versions of (d,p)
reaction theories.


title: Marangoni elasticity of flowing soap films

abstract:
  We measure the Marangoni elasticity of a flowing soap film to be 22 dyne/cm
irrespective of its width, thickness, flow speed, or the bulk soap
concentration. We perform this measurement by generating an oblique shock in
the soap film and measuring the shock angle, flow speed and thickness. We
postulate that the elasticity is constant because the film surface is crowded
with soap molecules. Our method allows non-destructive measurement of flowing
soap film elasticity, and the value 22 dyne/cm is likely applicable to other
similarly constructed flowing soap films.


title: Transitive closure and transitive reduction in bidirected graphs

abstract:
  In a bidirected graph an edge has a direction at each end, so bidirected
graphs generalize directed graphs. We generalize the definitions of transitive
closure and transitive reduction from directed graphs to bidirected graphs by
introducing new notions of bipath and bicircuit that generalize directed paths
and cycles. We show how transitive reduction is related to transitive closure
and to the matroids of the signed graph corresponding to the bidirected graph.


title: On the Thermodynamics of the Swift-Hohenberg Theory

abstract:
  We present the microbalance including the microforces, the first- and
second-order microstresses for the Swift--Hohenberg equation concomitantly with
their constitutive equations, which are consistent with the free-energy
imbalance. We provide an explicit form for the microstress structure for a
free-energy functional endowed with second-order spatial derivatives.
Additionally, we generalize the Swift--Hohenberg theory via a proper
constitutive process. Finally, we present one highly-resolved three-dimensional
numerical simulation to demonstrate the particular form of the resulting
microstresses and their interactions in the evolution of the Swift--Hohenberg
equation.


title:
A Simple Experimental Model to Investigate Force Range for Membrane
  Nanotube Formation

abstract:
  The presence of membrane tubules in living cells is essential to many
biological processes. In cells, one mechanism to form nanosized lipid tubules
is via molecular motor induced bilayer extraction. In this paper, we describe a
simple experimental model to investigate the forces required for lipid tube
formation using kinesin motors anchored to DOPC vesicles. Previous related
studies have used molecular motors actively pulling on the membrane to extract
a nanotube. Here, we invert the system geometry; molecular motors are used as
static anchors linking DOPC vesicles to a two-dimensional microtubule network
and an external flow is introduced to generate nanotubes facilitated by the
drag force. We found that a drag force of ~7 pN was sufficient for tubule
extraction for vesicles ranging from 1 to 2 um in radius. By our method, we
found that the force generated by a single molecular motor was sufficient for
membrane tubule extraction from a spherical lipid vesicle.


title: On the Stokes matrices of the $tt^*$-Toda equation

abstract:
  We derive a formula for the signature of the symmetrized Stokes matrix
$\cal{S}+\cal{S}^\mathrm{T}$ for the $tt^*$-Toda equation. As a corollary, we
verify a conjecture of Cecotti and Vafa regarding when
$\cal{S}+\cal{S}^\mathrm{T}$ is positive definite, reminiscent of a formula of
Beukers and Heckmann for the generalized hypergeometric equation. The condition
that $\cal{S}+\cal{S}^\mathrm{T}$ is positive definite is prominent in the work
of Cecotti and Vafa on the $tt^*$ equation; we show that the Stokes matrices
$\cal{S}$ satisfying this condition are parameterized by the points of an open
convex polytope.


title:
Intra-chain organisation of hydrophobic residues controls inter-chain
  aggregation rates of amphiphilic polymers

abstract:
  Aggregation of amphiphiles through the action of hydrophobic interactions is
a common feature in soft condensed matter systems and is of particular
importance in the context of biophysics as it underlies both the generation of
functional biological machinery as well as the formation of pathological
misassembled states of proteins. Here we explore the aggregation behaviour of
amphiphilic polymers using lattice Monte-Carlo calculations and show that the
distribution of hydrophobic residues within the polymer sequence determines the
facility with which dry/wet interfaces can be created and that such interfaces
drive the aggregation process.


title:
Cooperative Protofilament Switching Emerges from Inter-Motor
  Interference in Multiple-Motor Transport

abstract:
  Within living cells, the transport of cargo is accomplished by groups of
molecular motors. Such collective transport could utilize mechanisms which
emerge from inter-motor interactions in ways that are yet to be fully
understood. Here we combined experimental measurements of two-kinesin transport
with a theoretical framework to investigate the functional ramifications of
inter-motor interactions on individual motor function and collective cargo
transport. In contrast to kinesin's low sidestepping frequency when present as
a single motor, with exactly two kinesins per cargo, we observed substantial
motion perpendicular to the microtubule. Our model captures a
surface-associated mode of kinesin, which is only accessible via inter-motor
interference in groups, in which kinesin diffuses along the microtubule surface
and rapidly "hops" between protofilaments without dissociating from the
microtubule. Critically, each kinesin transitions dynamically between the
active stepping mode and this weak surface-associated mode enhancing local
exploration of the microtubule surface, possibly enabling cellular cargos to
overcome macromolecular crowding and to navigate obstacles along microtubule
tracks without sacrificing overall travel distance.


title: Effective Capacity in MIMO Channels with Arbitrary Inputs

abstract:
  Recently, communication systems that are both spectrum and energy efficient
have attracted significant attention. Different from the existing research, we
investigate the throughput and energy efficiency of a general class of
multiple-input and multiple-output systems with arbitrary inputs when they are
subject to statistical quality-of-service (QoS) constraints, which are imposed
as limits on the delay violation and buffer overflow probabilities. We employ
the effective capacity as the performance metric. We obtain the optimal input
covariance matrix that maximizes the effective capacity under a short-term
average power constraint. Following that, we perform an asymptotic analysis of
the effective capacity in the low signal-to-noise ratio and large-scale antenna
regimes. In the low signal-to-noise ratio regime analysis, we utilize the first
and second derivatives of the effective capacity when the signal-to-noise ratio
approaches zero in order to determine the minimum energy-per-bit and also the
slope of the effective capacity versus energy-per-bit curve at the minimum
energy-per-bit. We observe that the minimum energy-per-bit is independent of
the input distribution, whereas the slope depends on the input distribution. In
the large-scale antenna analysis, we show that the effective capacity
approaches the average transmission rate in the channel with the increasing
number of transmit and/or receive antennas. Particularly, the gap between the
effective capacity and the average transmission rate in the channel, which is
caused by the QoS constraints, is minimized with the number of antennas. In
addition, we put forward the non-asymptotic backlog and delay violation bounds
by utilizing the effective capacity. Finally, we substantiate our analytical
results through numerical illustrations.


title: Photon counting spectroscopic CT with dynamic beam attenuator

abstract:
  Purpose: Photon counting (PC) computed tomography (CT) can provide material
selective CT imaging at lowest patient dose but it suffers from suboptimal
count rate. A dynamic beam attenuator (DBA) can help with count rate by
modulating x-ray beam intensity such that the low attenuating areas of the
patient receive lower exposure, and detector behind these areas is not
overexposed. However, DBA may harden the beam and cause artifacts and errors.
This work investigates positive and negative effects of using DBA in PCCT.
Methods: A simple PCCT with single energy bin, spectroscopic PCCT with 2 and 5
energy bins, and conventional energy integrating CT with and without DBA were
simulated and investigated using 120kVp tube voltage and 14mGy air dose. The
DBAs were modeled as made from soft tissue (ST) equivalent material, iron (Fe),
and holmium (Ho) K-edge material. A cylindrical CT phantom and chest phantom
with iodine and CaCO3 contrast elements were used. Image artifacts and
quantification errors in general and material decomposed CT were determined.
Results: Simple PCCT exhibited major image artifacts and quantification errors
when DBAs were used. The artifacts and errors were decreased with 2bin
spectroscopic PCCT and nearly eliminated with 5bin spectroscopic CT. The photon
starvation noise did present with Fe-DBA due to strong absorption of lower
energy photons. The 5bin PCCT with ST-DBA and Ho-DBA were nearly free of
artifacts and photon starvation noise. The Ho-DBA better preserved low energy
photons and decreased beam hardening artifacts, and improved material
decomposition. Also, the Ho-DBA was also miniature having 1.4mm thickness and
2cm length, much smaller than Fe-DBA. Conclusion: DBA fabricated from K-edge
material such as Ho can address count rate problem of PCCT and provide
miniature size, minimal image artifacts, and improved material decomposition at
lowest patient dose.


title: Urban association rules: uncovering linked trips for shopping behavior

abstract:
  In this article, we introduce the method of urban association rules and its
uses for extracting frequently appearing combinations of stores that are
visited together to characterize shoppers' behaviors. The Apriori algorithm is
used to extract the association rules (i.e., if -> result) from customer
transaction datasets in a market-basket analysis. An application to our
large-scale and anonymized bank card transaction dataset enables us to output
linked trips for shopping all over the city: the method enables us to predict
the other shops most likely to be visited by a customer given a particular shop
that was already visited as an input. In addition, our methodology can consider
all transaction activities conducted by customers for a whole city in addition
to the location of stores dispersed in the city. This approach enables us to
uncover not only simple linked trips such as transition movements between
stores but also the edge weight for each linked trip in the specific district.
Thus, the proposed methodology can complement conventional research methods.
Enhancing understanding of people's shopping behaviors could be useful for city
authorities and urban practitioners for effective urban management. The results
also help individual retailers to rearrange their services by accommodating the
needs of their customers' habits to enhance their shopping experience.


title:
Initial-boundary value problems for nearly incompressible vector fields,
  and applications to the Keyfitz and Kranzer system

abstract:
  We establish existence and uniqueness results for initial boundary value
problems with nearly incompressible vector fields. We then apply our results to
establish well-posedness of the initial-boundary value problem for the Keyfitz
and Kranzer system of conservation laws in several space dimensions.


title: A Birth and Death Process for Bayesian Network Structure Inference

abstract:
  Bayesian networks (BNs) are graphical models that are useful for representing
high-dimensional probability distributions. There has been a great deal of
interest in recent years in the NP-hard problem of learning the structure of a
BN from observed data. Typically, one assigns a score to various structures and
the search becomes an optimization problem that can be approached with either
deterministic or stochastic methods. In this paper, we walk through the space
of graphs by modeling the appearance and disappearance of edges as a birth and
death process and compare our novel approach to the popular Metropolis-Hastings
search strategy. We give empirical evidence that the birth and death process
has superior mixing properties.


title:
Spin-orbit-induced resonances and threshold anomalies in a reduced
  dimension Fermi gas

abstract:
  We calculate the reflection and transmission probabilities in a
one-dimensional Fermi gas with an equal mixing of the Rashba and Dresselhaus
spin-orbit coupling (RD-SOC) produced by an external Raman laser field. These
probabilities are computed over multiple relevant energy ranges within the
pseudo-potential approximation. Strong scattering resonances are found whenever
the incident energy approaches either a scattering threshold or a quasi-bound
state attached to one of the energetically closed higher dispersion branches. A
striking difference is demonstrated between two very different regimes set by
the Raman laser intensity, namely between scattering for the single- minimum
dispersion versus the double-minimum dispersion at the lowest threshold. The
presence of RD-SOC together with the Raman field fundamentally changes the
scattering behavior and enables the realization of very different
one-dimensional theoretical models in a single experimental setup when combined
with a confinement-induced resonance.


title:
Discovering of boundedness and continuity of random fields by means of
  partition entropic scheme

abstract:
  We construct a new sufficient conditions for boundedness or continuity of
arbitrary random fields relying on the so-called partition scheme, alike in the
classical majorizing measure method.
  We deduce also the used in the practice (statistics, method Monte-Carlo etc.)
exact exponential estimates for tail of distribution of maximum for random
field satisfying formulated in this report conditions.


title:
A large scale study of SVM based methods for abstract screening in
  systematic reviews

abstract:
  A major task in systematic reviews is abstract screening, i.e., excluding,
often hundreds or thousand of, irrelevant citations returned from a database
search based on titles and abstracts. Thus, a systematic review platform that
can automate the abstract screening process is of huge importance. Several
methods have been proposed for this task. However, it is very hard to clearly
understand the applicability of these methods in a systematic review platform
because of the following challenges: (1) the use of non-overlapping metrics for
the evaluation of the proposed methods, (2) usage of features that are very
hard to collect, (3) using a small set of reviews for the evaluation, and (4)
no solid statistical testing or equivalence grouping of the methods. In this
paper, we use feature representation that can be extracted per citation. We
evaluate SVM-based methods (commonly used) on a large set of reviews ($61$) and
metrics ($11$) to provide equivalence grouping of methods based on a solid
statistical test. Our analysis also includes a strong variability of the
metrics using $500$x$2$ cross validation. While some methods shine for
different metrics and for different datasets, there is no single method that
dominates the pack. Furthermore, we observe that in some cases relevant
(included) citations can be found after screening only 15-20% of them via a
certainty based sampling. A few included citations present outlying
characteristics and can only be found after a very large number of screening
steps. Finally, we present an ensemble algorithm for producing a $5$-star
rating of citations based on their relevance. Such algorithm combines the best
methods from our evaluation and through its $5$-star rating outputs a more
easy-to-consume prediction.


title:
Systematic non-LTE study of the $-2.6 \le$ [Fe/H] $\le 0.2$ F and G
  dwarfs in the solar neighbourhood. II. Abundance patterns from Li to Eu

abstract:
  For the first time, we present an extensive study of stars with individual
non-local thermodynamic equilibrium (NLTE) abundances for 17 chemical elements
from Li to Eu in a sample of stars uniformly distributed over the $-2.62 \le$
[Fe/H] $\le +0.24$ metallicity range that is suitable for the Galactic chemical
evolution research. The star sample has been kinematically selected to trace
the Galactic thin and thick disks and halo. We find new and improve earlier
results as follows. (i) The element-to-iron ratios for Mg, Si, Ca, and Ti form
a MP plateau at a similar height of 0.3~dex, and the knee occurs at common
[Fe/H] $\simeq -0.8$. The knee at the same metallicity is observed for [O/Fe],
and the MP plateau is formed at [O/Fe] = 0.61. (ii) The upward trend of [C/O]
with decreasing metallicity exists at [Fe/H] $< -1.2$, supporting the earlier
finding of Akerman et al. (iii) An underabundance of Na relative to Mg in the
[Fe/H] $< -1$ stars is nearly constant, with the mean [Na/Mg] $\simeq -0.5$.
(iv) The K/Sc, Ca/Sc, and Ti/Sc ratios form well-defined trends, suggesting a
common site of the K-Ti production. (v) Sr follows the Fe abundance down to
[Fe/H] $\simeq -2.5$, while Zr is enhanced in MP stars. (vi) The comparisons of
our results with some widely used Galactic evolution models are given. The use
of the NLTE element abundances raises credit to the interpretation of the data
in the context of the chemical evolution of the Galaxy.


title: Large deviation for lasso diffusion process

abstract:
  The aim of the present paper is to extend the large deviation with
discontinuous statistics studied in \cite{BDE} to the diffusion
$d\mathbf{x}^\varepsilon = -\{\mathbf{A}^\top (\mathbf{A}
\mathbf{x}^\varepsilon - \mathbf{y}) + \mu sgn(\mathbf{x}^\varepsilon)\}dt +
\varepsilon d\mathbf{w}$. The discontinuity of the drift of the diffusion
discussed in \cite{BDE} is equal to the hyperplane $\{\mathbf{x} \in
\mathbb{R}^d:\ x_1=0\}$, however, in our case the discontinuity is more complex
and is equal to the set $\{\mathbf{x} \in \mathbb{R}^d:\ \prod_{i=1}^dx_i=0\}$.


title:
Penalized Ensemble Kalman Filters for High Dimensional Non-linear
  Systems

abstract:
  The ensemble Kalman filter (EnKF) is a data assimilation technique that uses
an ensemble of models, updated with data, to track the time evolution of a
usually non-linear system. It does so by using an empirical approximation to
the well-known Kalman filter. However, its performance can suffer when the
ensemble size is smaller than the state space, as is often necessary for
computationally burdensome models. This scenario means that the empirical
estimate of the state covariance is not full rank and possibly quite noisy. To
solve this problem in this high dimensional regime, we propose a
computationally fast and easy to implement algorithm called the penalized
ensemble Kalman filter (PEnKF). Under certain conditions, it can be
theoretically proven that the PEnKF will be accurate (the estimation error will
converge to zero) despite having fewer ensemble members than state dimensions.
Further, as contrasted to localization methods, the proposed approach learns
the covariance structure associated with the dynamical system. These
theoretical results are supported with simulations of several non-linear and
high dimensional systems.


title:
Pancharatnam-Berry phase induced spin-selective transmission in
  herringbone dielectric metamaterials

abstract:
  Manipulating the polarisation of light is crucial for sensing and imaging
applications. One such aspect in particular is selective transmission of one
circular polarisation (spin) when light is transmitted through a medium or a
device. However, most present methods of achieving this have relatively low
efficiency and selectivity, whilst high selectivity examples rely on lossy and
complex three-dimensional helical or multilayer structures. Here, we propose a
dielectric metamaterial approach for achieving spin-selective transmission of
electromagnetic waves, utilizing spin-controlled constructive or destructive
interference between two Pancharatnam-Berry (PB) phases in conjunction with
propagative dynamic phase. The dielectric metamaterial, consisting of
monolithic silicon herringbone structures, exhibits a broadband operation in
the terahertz regime whilst obtaining a spin-selective efficiency upwards of
60%. Such a device is robust and is not easily degraded by errors in
fabrication.


title:
Coherent structure coloring: identification of coherent structures from
  sparse data using graph theory

abstract:
  We present a frame-invariant method for detecting coherent structures from
Lagrangian flow trajectories that can be sparse in number, as is the case in
many fluid mechanics applications of practical interest. The method, based on
principles used in graph coloring and spectral graph drawing algorithms,
examines a measure of the kinematic dissimilarity of all pairs of fluid
trajectories, either measured experimentally, e.g. using particle tracking
velocimetry; or numerically, by advecting fluid particles in the Eulerian
velocity field. Coherence is assigned to groups of particles whose kinematics
remain similar throughout the time interval for which trajectory data is
available, regardless of their physical proximity to one another. Through the
use of several analytical and experimental validation cases, this algorithm is
shown to robustly detect coherent structures using significantly less flow data
than is required by existing spectral graph theory methods.


title: Expected Depth of Random Walks on Groups

abstract:
  For $G$ a finitely generated group and $g \in G$, we say $g$ is detected by a
normal subgroup $N \lhd G$ if $g \notin N$. The depth $D_G(g)$ of $g$ is the
lowest index of a normal, finite index subgroup $N$ that detects $g$. In this
paper we study the expected depth, $\mathbb E[D_G(X_n)]$, where $X_n$ is a
random walk on $G$. We give several criteria that imply that $$\mathbb
E[D_G(X_n)] \xrightarrow[n\to \infty]{} 2 + \sum_{k \geq
2}\frac{1}{[G:\Lambda_k]}\, ,$$ where $\Lambda_k$ is the intersection of all
normal subgroups of index at most $k$. In particular, the equality holds in the
class of all nilpotent groups and in the class of all linear groups satisfying
Kazhdan Property $(T)$. We explain how the right-hand side above appears as a
natural limit and also give an example where the convergence does not hold.


title:
Convergence of a Grassmannian Gradient Descent Algorithm for Subspace
  Estimation From Undersampled Data

abstract:
  Subspace learning and matrix factorization problems have great many
applications in science and engineering, and efficient algorithms are critical
as dataset sizes continue to grow. Many relevant problem formulations are
non-convex, and in a variety of contexts it has been observed that solving the
non-convex problem directly is not only efficient but reliably accurate. We
discuss convergence theory for a particular method: first order incremental
gradient descent constrained to the Grassmannian. The output of the algorithm
is an orthonormal basis for a $d$-dimensional subspace spanned by an input
streaming data matrix. We study two sampling cases: where each data vector of
the streaming matrix is fully sampled, or where it is undersampled by a
sampling matrix $A_t\in \mathbb{R}^{m\times n}$ with $m\ll n$. Our results
cover two cases, where $A_t$ is Gaussian or a subset of rows of the identity
matrix. We propose an adaptive stepsize scheme that depends only on the sampled
data and algorithm outputs. We prove that with fully sampled data, the stepsize
scheme maximizes the improvement of our convergence metric at each iteration,
and this method converges from any random initialization to the true subspace,
despite the non-convex formulation and orthogonality constraints. For the case
of undersampled data, we establish monotonic expected improvement on the
defined convergence metric for each iteration with high probability.


title: One-dimensional long-range percolation: a numerical study

abstract:
  In this paper we study bond percolation on a one-dimensional chain with
power-law bond probability $C/ r^{1+\sigma}$, where $r$ is the distance length
between distinct sites. We introduce and test an order $N$ Monte Carlo
algorithm and we determine as a function of $\sigma$ the critical value $C_{c}$
at which percolation occurs. The critical exponents in the range $0<\sigma<1$
are reported and compared with mean-field and $\varepsilon$-expansion results.
Our analysis is in agreement, up to a numerical precision $\approx 10^{-3}$,
with the mean field result for the anomalous dimension $\eta=2-\sigma$, showing
that there is no correction to $\eta$ due to correlation effects.


title: Fermionic Lensing in Smooth Graphene P-N Junctions

abstract:
  Focusing of electron waves in graphene p-n junctions is a striking
manifestation of fermionic negative refraction. We analyze lensing in smooth
p-n junctions and find that it differs in several interesting ways from that in
the previously studied sharp p-n junctions. Most importantly, while the overall
negative-refraction behavior remains unchanged, the image at the focal point
undergoes additional broadening due to Klein tunneling in the junction. We
develop a theory of image broadening and estimate the effect for practically
interesting system parameter values.


title: Ultrafast Angle-Resolved Photoemission Spectroscopy of Quantum Materials

abstract:
  Techniques in time- and angle-resolved photoemission spectroscopy have
facilitated a number of recent advances in the study of quantum materials. We
review developments in this field related to the study of incoherent
nonequilibrium electron dynamics, the analysis of interactions between
electrons and collective excitations, the exploration of dressed-state physics,
and the illumination of unoccupied band structure. Future prospects are also
discussed.


title:
Homogenization and Orowan's law for anisotropic fractional operators of
  any order

abstract:
  We consider an anisotropic L\'evy operator $\mathcal{I}_s$ of any order
$s\in(0,1)$ and we consider the homogenization properties of an evolution
equation.
  The scaling properties and the effective Hamiltonian that we obtain is
different according to the cases $s<1/2$ and $s>1/2$.
  In the isotropic onedimensional case, we also prove a statement related to
the so-called Orowan's law, that is an appropriate scaling of the effective
Hamiltonian presents a linear behavior.


title: Weakly coupled mean-field game systems

abstract:
  Here, we prove the existence of solutions to first-order mean-field games
(MFGs) arising in optimal switching. First, we use the penalization method to
construct approximate solutions. Then, we prove uniform estimates for the
penalized problem. Finally, by a limiting procedure, we obtain solutions to the
MFG problem.


title: Simpson's construction of varieties with many local systems

abstract:
  The purpose of this largely expository note is to give some examples of
smooth projective varieties with zero first Betti number but nontrivial
families of local systems of higher ranks. The most interesting examples are
due to Simpson.


title:
Surface-electrode trap with an integrated permanent magnet for
  generating a magnetic-field gradient at trapped ions

abstract:
  We report on a surface-electrode trap with SmCo magnets arranged in a
quadrupole configuration underneath the trap electrode. Because the distance
between the magnets and the trapped ions can be as little as several hundred
micrometers, a large magnetic field is produced without any heat management.
The magnetic-field gradient was measured using the Zeeman splitting of a single
trapped $^{40}$Ca$^+$ ion at several positions, and a field gradient of 36 T/m
was obtained. Such a field gradient is useful for the generation of a
state-dependent force, which is important for quantum simulation and/or quantum
gate operation using radio-frequency or microwave radiation.


title:
Tuning parameter calibration for $\ell_1$-regularized logistic
  regression

abstract:
  Feature selection is a standard approach to understanding and modeling
high-dimensional classification data, but the corresponding statistical methods
hinge on tuning parameters that are difficult to calibrate. In particular,
existing calibration schemes in the logistic regression framework lack any
finite sample guarantees. In this paper, we introduce a novel calibration
scheme for $\ell_1$-penalized logistic regression. It is based on simple tests
along the tuning parameter path and is equipped with optimal guarantees for
feature selection. It is also amenable to easy and efficient implementations,
and it rivals or outmatches existing methods in simulations and real data
applications.


title:
Sub-diffusion processes in Hilbert space and their associated stochastic
  differential equations and Fokker-Planck-Kolmogorov equations

abstract:
  This paper focuses on the time-changed Q-Wiener process, a Hilbert
space-valued sub-diffusion. It is a martingale with respect to an appropriate
filtration, hence a stochastic integral with respect to it is definable. For
the resulting integral, two change of variables formulas are derived. Via a
duality theorem for integrals, existence and uniqueness theorems for stochastic
differential equations (SDEs) driven by the time-changed Q-Wiener process are
discussed. Associated fractional Fokker-Planck-Kolmogorov equations are derived
using either a time-changed It\^o formula or duality. Connections are
established between three integrals driven by time-changed versions of the
Q-Wiener process, cylindrical Wiener process, and martingale measure.


title: Real Stability Testing

abstract:
  We give a strongly polynomial time algorithm which determines whether or not
a bivariate polynomial is real stable. As a corollary, this implies an
algorithm for testing whether a given linear transformation on univariate
polynomials preserves real-rootedness. The proof exploits properties of
hyperbolic polynomials to reduce real stability testing to testing
nonnegativity of a finite number of polynomials on an interval.


title: Investigations on a Thermoacoustic Refrigerator

abstract:
  Thermoacoustic Refrigerators use acoustic power for generating cold
temperatures. Development of refrigerators based on the thermoacoustic
technology is a novel solution to the present day need of cooling, without
causing environmental hazards. With added advantages such as minimal moving
parts and absence of CFC refrigerants, these devices can attain low
temperatures maintaining a compact size. The present work describes an in-depth
theoretical analysis of standing wave thermoacoustic refrigerators. This
consists of detailed parametric studies, transient state analysis, and a design
using an available simulation software. Design and construction of a
thermoacoustic refrigerator using a commercially available electro-dynamic
motor is also presented.


title:
Sentence Segmentation in Narrative Transcripts from Neuropsychological
  Tests using Recurrent Convolutional Neural Networks

abstract:
  Automated discourse analysis tools based on Natural Language Processing (NLP)
aiming at the diagnosis of language-impairing dementias generally extract
several textual metrics of narrative transcripts. However, the absence of
sentence boundary segmentation in the transcripts prevents the direct
application of NLP methods which rely on these marks to function properly, such
as taggers and parsers. We present the first steps taken towards automatic
neuropsychological evaluation based on narrative discourse analysis, presenting
a new automatic sentence segmentation method for impaired speech. Our model
uses recurrent convolutional neural networks with prosodic, Part of Speech
(PoS) features, and word embeddings. It was evaluated intrinsically on
impaired, spontaneous speech, as well as, normal, prepared speech, and presents
better results for healthy elderly (CTL) (F1 = 0.74) and Mild Cognitive
Impairment (MCI) patients (F1 = 0.70) than the Conditional Random Fields method
(F1 = 0.55 and 0.53, respectively) used in the same context of our study. The
results suggest that our model is robust for impaired speech and can be used in
automated discourse analysis tools to differentiate narratives produced by MCI
and CTL.


title: The Atiyah-Bott formula and connectivity in chiral Koszul duality

abstract:
  The $\otimes^\star$-monoidal structure on the category of sheaves on the
$\mathrm{Ran}$ space is not pro-nilpotent in the sense of Francis-Gaitsgory.
However, under some connectivity assumptions, we prove that Koszul duality
induces an equivalence of categories and that this equivalence behaves nicely
with respect to Verdier duality on the $\mathrm{Ran}$ space and integrating
along the $\mathrm{Ran}$ space, i.e. taking factorization homology. Based on
ideas sketched by Gaitsgory, we show that these results also offer a simpler
alternative to one of the two main steps in the proof of the Atiyah-Bott
formula given in Gaitsgory-Lurie and Gaitsgory.


title: A note on the reverse mathematics of the sorites

abstract:
  Sorites is an ancient piece of paradoxical reasoning pertaining to sets with
the following properties: (Supervenience) elements of the set are mapped into
some set of "attributes", (Tolerance) if an element has a given attribute then
so are the elements in some vicinity of this element, and (Connectedness) such
vicinities can be arranged into pairwise overlapping finite chains connecting
two elements with different attributes. Obviously, if Superveneince is assumed,
then (1) Tolerance implies lack of Connectedness, and (2) Connectedness implies
lack of Tolerance. Using a very general but precise definition of "vicinity",
Dzhafarov and Dzhafarov (2010) offered two formalizations of these mutual
contrapositions. Mathematically, the formalizations are equally valid, but in
this paper, we offer a different basis by which to compare them. Namely, we
show that the formalizations have different proof-theoretic strengths when
measured in the framework of reverse mathematics: the formalization of (1) is
provable in $\mathsf{RCA}_0$, while the formalization of (2) is equivalent to
$\mathsf{ACA}_0$ over $\mathsf{RCA}_0$. Thus, in a certain precise sense, the
approach of (1) is more constructive than that of (2).


title: Augmenting Mobile Phone Interaction with Face-Engaged Gestures

abstract:
  The movement of a user's face, easily detected by a smartphone's front
camera, is an underexploited input modality for mobile interactions. We
introduce three sets of face-engaged interaction techniques for augmenting the
traditional mobile inputs, which leverages the combination of the head
movements with touch gestures and device motions, all sensed via the phone's
built-in sensors. We systematically present the space of design considerations
for mobile interactions using one or more of the three input modalities (i.e.,
touch, motion, and head). The additional affordances of the proposed techniques
expand the mobile interaction vocabulary, and can facilitate unique usage
scenarios such as one-hand or touch-free interaction. An initial evaluation was
conducted and users had positive reactions to the new techniques, indicating
the promise of an intuitive and convenient user experience.


title:
Electromagnetic transmittance in alternating material-metamaterial
  layered structures

abstract:
  Using the transfer matrix method we examine the parametric behavior of the
transmittance of TE and TM electromagnetic plane waves propagating in frequency
range which are far from the absorption bands of a periodic multilayered
system. We focus on the dependence of the transmittance on the frequency and
angle of incidence of the electromagnetic wave for the case in which the
periodic structure comprises alternating material-metamaterial layers of
various permittivities and permeabilities. A specific example of high
transmittance at any angle of incidence in the visible region of the spectrum
is identified


title:
Toward a Designable Extracellular Matrix: Molecular Dynamics Simulations
  of an Engineered Laminin-mimetic, Elastin-like Fusion Protein

abstract:
  Native extracellular matrices (ECMs), such as those of the human brain and
other neural tissues, exhibit networks of molecular interactions between
specific matrix proteins and other tissue components. Guided by these naturally
self-assembling supramolecular systems, we have designed a matrix-derived
protein chimera that contains a laminin globular-like (LG) domain fused to an
elastin-like polypeptide (ELP). All-atom, classical molecular dynamics
simulations of our designed laminin-elastin fusion protein reveal
temperature-dependent conformational changes, in terms of secondary structure
composition, solvent accessible surface area, hydrogen bonding, and surface
hydration. These properties illuminate the phase behavior of this fusion
protein, via the emergence of $\beta$-sheet character in
physiologically-relevant temperature ranges.


title: Coherence generating power of quantum unitary maps and beyond

abstract:
  Given a preferred orthonormal basis $B$ in the Hilbert space of a quantum
system we define a measure of the coherence generating power of a unitary
operation with respect to $B$. This measure is the average coherence generated
by the operation acting on a uniform ensemble of incoherent states. We give its
explicit analytical form in any dimension and provide an operational protocol
to directly detect it. We characterize the set of unitaries with maximal
coherence generating power and study the properties of our measure when the
unitary is drawn at random from the Haar distribution. For large state-space
dimension a random unitary has, with overwhelming probability, nearly maximal
coherence generating power with respect to any basis. Finally, extensions to
general unital quantum operations and the relation to the concept of asymmetry
are discussed.


title:
Generalized lower-hybrid mode with, density gradient, equilibrium ExB
  drift, collisions and finite electron Larmor radius: Numerical studies with
  MATLAB solver

abstract:
  MATLAB solver for general dispersion relation has been developed to study
local instabilities in partially magnetized plasmas typical for ExB discharges.
Several examples of the Simon-Hoh, lower-hybrid and ion-sound instabilities
with the parameters typical for Penning discharge are shown. This solver allows
parametrically investigate the local dispersion relation for the wide range of
plasma parameters and prepare reports.


title: Text Network Exploration via Heterogeneous Web of Topics

abstract:
  A text network refers to a data type that each vertex is associated with a
text document and the relationship between documents is represented by edges.
The proliferation of text networks such as hyperlinked webpages and academic
citation networks has led to an increasing demand for quickly developing a
general sense of a new text network, namely text network exploration. In this
paper, we address the problem of text network exploration through constructing
a heterogeneous web of topics, which allows people to investigate a text
network associating word level with document level. To achieve this, a
probabilistic generative model for text and links is proposed, where three
different relationships in the heterogeneous topic web are quantified. We also
develop a prototype demo system named TopicAtlas to exhibit such heterogeneous
topic web, and demonstrate how this system can facilitate the task of text
network exploration. Extensive qualitative analyses are included to verify the
effectiveness of this heterogeneous topic web. Besides, we validate our model
on real-life text networks, showing that it preserves good performance on
objective evaluation metrics.


title: Out-of-time-order correlations in many-body localized and thermal phases

abstract:
  We use the out-of-time-order (OTO) correlators to study the slow dynamics in
the many-body localized (MBL) phase. We investigate OTO correlators in the
effective ("l-bit") model of the MBL phase, and show that their amplitudes
after disorder averaging approach their long-time limits as power-laws of time.
This power-law dynamics is due to dephasing caused by interactions between the
localized operators that fall off exponentially with distance. The long-time
limits of the OTO correlators are determined by the overlaps of the local
operators with the conserved l-bits. We demonstrate numerically our results in
the effective model and three other more "realistic" spin chain models.
Furthermore, we extend our calculations to the thermal phase and find that for
a time-independent Hamiltonian, the OTO correlators also appear to vanish as a
power law at long time, perhaps due to coupling to conserved densities. In
contrast, we find that in the thermal phase of a Floquet spin model with no
conserved densities the OTO correlator decays exponentially at long times.


title: Strangeness at finite temperature from Lattice QCD

abstract:
  The precision reached by recent lattice QCD results allows for the first time
to investigate whether the measured hadronic spectrum is missing some
additional strange states, which are predicted by the Quark Model but have not
yet been detected. This can be done by comparing some sensitive thermodynamic
observables from lattice QCD to the predictions of the Hadron Resonance Gas
model (with the inclusion of decays [3]). We propose a set of specific
observables, defined as linear combinations of conserved charge fluctuations,
which allow to investigate this issue for baryons containing one or more
strange quarks separately. Applications of these observables to isolate the
multiplicity fluctuations of kaons from lattice QCD, and their comparison with
the experimental results, are also discussed.


title:
Spin-transfer torque in ferromagnetic bilayers generated by anomalous
  Hall effect and anisotropic magnetoresistance

abstract:
  We propose an experimental scheme to determine the spin-transfer torque
efficiency excited by the spin-orbit interaction in ferromagnetic bilayers from
the measurement of the longitudinal magnetoresistace. Solving a diffusive
spin-transport theory with appropriate boundary conditions gives an analytical
formula of the longitudinal charge current density. The longitudinal charge
current has a term that is proportional to the square of the spin-transfer
torque efficiency and that also depends on the ratio of the film thickness to
the spin diffusion length of the ferromagnet. Extracting this contribution from
measurements of the longitudinal resistivity as a function of the thickness can
give the spin-transfer torque efficiency.


title:
Universal relations and normal phase of an ultracold Fermi gas with
  coexisting $s$- and $p$-wave interactions

abstract:
  We study the universal relations and normal-phase thermodynamics of a
two-component ultracold Fermi gas with coexisting $s$- and $p$-wave
interactions. Due to the orthogonality of two-body wave functions of different
scattering channels, the universal thermodynamic relations of the system appear
to be direct summations of contributions from each partial-wave scattering
channels. These universal relations are dictated by a set of contacts, which
can be associated with either $s$- or $p$-wave interactions. Interestingly, due
to the interplay of $s$- and $p$-wave interactions on the many-body level, the
contacts, and hence all the relevant thermodynamic quantities, behave
differently from those with only $s$- or $p$-wave interactions. These are
manifest in our numerical calculations based on second-order virial expansions
for $^{40}$K atoms under typical experimental parameters. A particularly
interesting finding is that, due to the coexistence of $s$- and $p$-wave
scatterings, the interaction energy of the repulsive branch features abrupt
changes across the $p$-wave resonances. Our results can be readily checked
experimentally for $^{40}$K atoms near the $198$G $p$-wave Feshbach resonance,
where multiple partial-wave scatterings naturally coexist.


title:
Large-time behavior of solutions to a thermo-diffusion system with
  Smoluchowski interactions

abstract:
  We prove the large time behavior of solutions to a coupled thermo-diffusion
arising in the modelling of the motion of hot colloidal particles in porous
media. Additionally, we also ensure the uniqueness of solutions of the target
problem. The main mathematical difficulty is due to the presence in the
right-hand side of the equations of products between temperature and
concentration gradients. Such terms mimic the so-called thermodynamic Soret and
Dufour effects. These are cross-coupling terms emphasizing in this context a
strong interplay between heat conduction and molecular diffusion.


title: Quantizing Weierstrass

abstract:
  We study the connection between the Eynard-Orantin topological recursion and
quantum curves for the family of genus one spectral curves given by the
Weierstrass equation. We construct quantizations of the spectral curve that
annihilate the perturbative and non-perturbative wave-functions. In particular,
for the non-perturbative wave-function, we prove, up to order hbar^5, that the
quantum curve satisfies the properties expected from matrix models. As a side
result, we obtain an infinite sequence of identities relating A-cycle integrals
of elliptic functions and quasi-modular forms.


title: The Distribution of p-Torsion in Degree p Cyclic Fields

abstract:
  We compute all the moments of the p-torsion in the first step of a filtration
of the class group defined by Gerth for cyclic fields of degree p,
unconditionally for p=3 and under GRH in general. We show that it satisfies a
distribution which Gerth conjectured as an extension of the
Cohen-Lenstra-Martinet conjectures. In the p=3 case this gives the distribution
of the 3-torsion of the class group modulo the Galois invariant part. We follow
the strategy used by Fouvry and Kluners in their proof of the distribution of
the 4-torsion in quadratic fields.


title:
Approximate Gram-Matrix Interpolation for Wideband Massive MU-MIMO
  Systems

abstract:
  Numerous linear and non-linear data-detection and precoding algorithms for
wideband massive multi-user (MU) multiple-input multiple-output (MIMO) wireless
systems that rely on orthogonal frequency-division multiplexing (OFDM) or
single-carrier frequency-division multiple access (SC-FDMA) require the
computation of the Gram matrix for each active subcarrier. Computing the Gram
matrix for each active subcarrier, however, results in excessively high
computational complexity. In this paper, we propose novel, approximate
algorithms that significantly reduce the complexity of Gram-matrix computation
by simultaneously exploiting correlation across subcarriers and channel
hardening. We show analytically that a small fraction of Gram-matrix
computations in combination with approximate interpolation schemes are
sufficient to achieve near-optimal error-rate performance at low computational
complexity in massive MU-MIMO systems. We also demonstrate that the proposed
methods exhibit improved robustness against channel-estimation errors compared
to exact Gram-matrix interpolation algorithms that typically require high
computational complexity.


title: Positivity for convective semi-discretizations

abstract:
  We propose a technique for investigating stability properties like positivity
and forward invariance of an interval for method-of-lines discretizations, and
apply the technique to study positivity preservation for a class of TVD
semi-discretizations of 1D scalar hyperbolic conservation laws. This technique
is a generalization of the approach suggested in ref. 12. We give more relaxed
conditions on the time-step for positivity preservation for slope-limited
semi-discretizations integrated in time with explicit Runge-Kutta methods. We
show that the step-size restrictions derived are sharp in a certain sense, and
that many higher-order explicit Runge-Kutta methods, including the classical
4th-order method and all non-confluent methods with a negative Butcher
coefficient, cannot generally maintain positivity for these
semi-discretizations under any positive step size. We also apply the proposed
technique to centered finite difference discretizations of scalar hyperbolic
and parabolic problems.


title:
H\"older continuity of velocity gradients for shear-thinning fluids
  under perfect slip boundary conditions

abstract:
  This paper is concerned with non-stationary flows of sheart-hinning fluids in
a bounded two-dimensional C^{2;1} domain. Assuming perfect slip boundary
conditions, we provide a proof of the existence of a solution with the H\"older
continuous velocity gradients and pressure under condition that a stress tensor
satisfies power-law with growth p\in[5/3; 2].


title:
A Note on Spectral Analysis in Automorphic Representation Theory for
  ${\rm GL}_2$: II

abstract:
  We generalize Zagiers work on regularized integral to the singular case in
the adelic setting. We develop necessary tools of treating various singular
cases of regularized triple product formulas, which appear naturally in the
work of Michel and Venkatsh on the subconvexity problem for $GL_2$.


title:
Protonation enhancement by dichloromethane doping in low-pressure
  photoionization

abstract:
  Doping has been used to enhance the ionization efficiency of analytes in
atmospheric pressure photoionization, which is based on charge exchange.
Compounds with excellent ionization efficiencies are usually chosen as dopants.
In this paper, we report a new phenomenon observed in low-pressure
photoionization: Protonation enhancement by dichloromethane (CH2Cl2) doping.
CH2Cl2 is not a common dopant due to its high ionization energy (11.33 eV). The
low-pressure photoionization source was built using a krypton VUV lamp that
emits photons with energies of 10.0 and 10.6 eV and was operated at 500-1000
Pa. Protonation of water, methanol, ethanol, and acetaldehyde was respectively
enhanced by 481.7 +/- 122.4, 197.8 +/- 18.8, 87.3 +/- 7.8, and 93.5 +/- 35.5
times after doping 291 ppmv CH2Cl2, meanwhile CH2Cl2 almost does not generate
noticeable ions itself. This phenomenon has not been documented in the
literature. A new protonation process involving in ion-pair and H-bond
formations was proposed to expound the phenomenon. The observed phenomenon
opens a new prospect for the improvement of the detection efficiency of VUV
photoionization.


title:
Experimental generation of a high-fidelity four-photon linear cluster
  state

abstract:
  Cluster state plays a crucial role in the one-way quantum computation. Here,
we propose and experimentally demonstrate a new scheme to prepare an
ultrahigh-fidelity four-photon linear cluster state via spontaneous parametric
down-conversion process. The state fidelity is measured to be
$0.9517\pm0.0027$. Our scheme can be directly extended to more photons to
generate N-qubit linear cluster state. Furthermore, our scheme is optimal for
generating photonic linear cluster states in the sense of achieving the maximal
success probability and having the simplest strategy. The key idea is that the
photon pairs are prepared in some special non-maximally entangled states
instead of the normal Bell states. To generate a 2N-qubit linear cluster state
from N pairs of entangled photons, only (N-1) Hong-Ou-Mandel interferences are
needed and a success probability of $(\frac{1}{4})^{N-1}$ is achieved.


title:
Probing the nature of phases across the phase transition at finite
  isospin chemical potential

abstract:
  We compare the low eigenvalue spectra of the Overlap Dirac operator on two
sets of configurations at $\mu_I/\mu_I^c$ = 0.5 and 1.5 generated with
dynamical staggered fermions at these isospin chemical potential on $24^3
\times 6$ lattices. We find very small changes in the number of zero modes and
low lying modes which is in stark contrast with those across the corresponding
finite temperature phases where one sees a drop across the phase transition.
Possible consequences are discussed.


title:
Three-dimensional X-ray visualization of axonal tracts in mouse brain
  hemisphere

abstract:
  Neurons transmit active potentials through axons, which are essential for the
brain to function. In this study, the axonal networks of the murine brain were
visualized with X-ray tomographic microscopy, also known as X-ray
microtomography or micro-CT. Murine brain samples were freeze-dried to
reconstitute the intrinsic contrast of tissue constituents and subjected to
X-ray visualization. A whole brain hemisphere visualized by absorption contrast
illustrated three-dimensional structures including those of the striatum,
corpus callosum, and anterior commissure. Axonal tracts observed in the
striatum start from the basal surface of the cerebral cortex and end at various
positions in the basal ganglia. The distribution of X-ray attenuation
coefficients indicated that differences in water and phospholipid content
between the myelin sheath and surrounding tissue constituents account for the
observed contrast. A rod-shaped cutout of brain tissue was also analyzed with a
phase retrieval method, wherein tissue microstructures could be resolved with
up to 2.7 {\mu}m resolution. Structures of axonal networks of the striatum were
reconstructed by tracing axonal tracts. Such an analysis should be able to
delineate the functional relationships of the brain regions involved in the
observed network.


title:
Updated measurement of the $e^+e^- \to \omega \pi^0 \to
  \pi^0\pi^0\gamma$ cross section with the SND detector

abstract:
  We analyze a 37 pb$^{-1}$ data sample collected with the SND detector at the
VEPP-2000 $e^+e^-$ collider in the center-of-mass energy range 1.05--2.00 GeV
and present an updated measurement of the $e^+e^- \to \omega \pi^0 \to
\pi^0\pi^0\gamma$ cross section. In particular, we correct the mistake in
radiative correction calculation made in our previous measurement based on a
part of the data. The measured cross section is fitted with the vector meson
dominance model with three $\rho$-like states and used to test the conserved
vector current hypothesis in the $\tau^-\to\omega\pi^-\nu_{\tau}$ decay.


title:
Ultracompact fiber integrated X-ray dosimeter based on scintillators
  coupled to a nano-optical antenna

abstract:
  High energy radiations are nowadays cornerstone in scientific, medical and
industrial imaging and cancer therapy. However, their detection and dosimetry
are restricted to systems of modest compactness that are not compatible with
endoscopy. Here, we report the first experimental imaging and dosimetry of
X-rays with an ultracompact sensor integrated at the end of a single mode
optical fiber (125 $\mu$m full diameter). We realize such a dosimeter by
coupling luminescent scintillators to a nano-optical antenna engineered at the
end of the fiber and by detecting in-fiber outcoupled luminescence with a
photon counter. Direct profile and real-time dosimetry of a X-ray focused beam
reveals a spatial resolution of a few microns together with a sensitivity
better than 10$^3$ X-photons$/$s$/\mu$m$^2$ at energies of 8-10 keV. Because
the nano-optical platform is auto-aligned with respect to the fiber, the
resulting dosimeter is plug-and-play, flexible, and it is suitable for ultralow
footprint endoscopic investigations at higher X-ray energies. Our nano-optical
approach thus offers the possibility of X-ray profiling and dosimetry in
ultra-confined environments, opening up new avenues in the fields of X-ray
imaging, real-time control of cancer radiotherapies and Curie therapies,
medical and industrial endoscopy, etc. With this study, nano-optical antennas
make a first key contribution to the development of X-ray sensing protocols and
architectures.


title: Regularity of the Eikonal equation with two vanishing entropies

abstract:
  The Aviles-Giga functional $I_{\epsilon}(u)=\int_{\Omega}
\frac{\left|1-\left|\nabla u\right|^2\right|^2}{\epsilon}+\epsilon
\left|\nabla^2 u\right|^2 \, dx$ is a well known second order functional that
models phenomena from blistering to liquid crystals. The zero energy states of
the Aviles-Giga functional have been characterized by Jabin, Otto, Perthame.
Among other results they showed that if $\lim_{n\rightarrow \infty}
I_{\epsilon_n}(u_n)=0$ for some sequence $u_n\in W^{2,2}_0(\Omega)$ and
$u=\lim_{n\rightarrow \infty} u_n$ then $\nabla u$ is Lipschitz continuous
outside a locally finite set. This is essentially a corollary to their theorem
that if $u$ is a solution to the Eikonal equation $\left|\nabla u\right|=1$
a.e. and if for every "entropy" $\Phi$ function $u$ satisfies
$\nabla\cdot\left[\Phi(\nabla u^{\perp})\right]=0$ distributionally in $\Omega$
then $\nabla u$ is locally Lipschitz continuous outside a locally finite set.
  In this paper we generalize this result by showing that if $\Omega$ is
bounded and simply connected, $u$ satisfies the Eikonal equation and if
  \begin{equation}
  \label{eqi88}
  \nabla\cdot\left(\Sigma_{e_1 e_2}(\nabla
u^{\perp})\right)=0\text{and}\nabla\cdot\left(\Sigma_{\epsilon_1
\epsilon_2}(\nabla u^{\perp})\right)=0\text{distributionally in}\Omega,
  \end{equation} where $\Sigma_{e_1 e_2}$ and $\Sigma_{\epsilon_1 \epsilon_2}$
are the entropies introduced by Ambrosio, DeLellis, Mantegazza, Jin, Kohn, then
$\nabla u$ is locally Lipschitz continuous outside a locally finite set.


title: The IC-indices of Some Complete Multipartite Graphs

abstract:
  A coloring of a connected graph $G$ is a function $f$ mapping the vertex set
of $G$ into the set of all integers. For any subgraph $H$ of $G$, we denote the
sum of the values of $f$ on the vertices of $H$ as $f(H)$. If for any integer
$k\in \{1,2,\cdots,f(G)\}$, there exists an induced connected subgraph $H$ of
$G$ such that $f(H) = k$, then the coloring $f$ is called an IC-coloring of
$G$. The IC-index of $G$, denoted as $M(G)$, is the maximum value of $f(G)$
over all possible IC-colorings $f$ of $G$. In this paper, we present a useful
method from which a lower bound on the IC-index of any complete multipartite
graph can be derived. Subsequently, we show that, for $m\geq 2 ~\mbox{and}
~n\geq 2$, our lower bound on $M(K_{1(n),m})$ is the exact value of it.


title:
Optimal compression of approximate inner products and dimension
  reduction

abstract:
  Let $X$ be a set of $n$ points of norm at most $1$ in the Euclidean space
$R^k$, and suppose $\varepsilon>0$. An $\varepsilon$-distance sketch for $X$ is
a data structure that, given any two points of $X$ enables one to recover the
square of the (Euclidean) distance between them up to an {\em additive} error
of $\varepsilon$. Let $f(n,k,\varepsilon)$ denote the minimum possible number
of bits of such a sketch. Here we determine $f(n,k,\varepsilon)$ up to a
constant factor for all $n \geq k \geq 1$ and all $\varepsilon \geq
\frac{1}{n^{0.49}}$. Our proof is algorithmic, and provides an efficient
algorithm for computing a sketch of size $O(f(n,k,\varepsilon)/n)$ for each
point, so that the square of the distance between any two points can be
computed from their sketches up to an additive error of $\varepsilon$ in time
linear in the length of the sketches. We also discuss the case of smaller
$\varepsilon>2/\sqrt n$ and obtain some new results about dimension reduction
in this range. In particular, we show that for any such $\varepsilon$ and any
$k \leq t=\frac{\log (2+\varepsilon^2 n)}{\varepsilon^2}$ there are
configurations of $n$ points in $R^k$ that cannot be embedded in $R^{\ell}$ for
$\ell < ck$ with $c$ a small absolute positive constant, without distorting
some inner products (and distances) by more than $\varepsilon$. On the positive
side, we provide a randomized polynomial time algorithm for a bipartite variant
of the Johnson-Lindenstrauss lemma in which scalar products are approximated up
to an additive error of at most $\varepsilon$. This variant allows a reduction
of the dimension down to $O(\frac{\log (2+\varepsilon^2 n)}{\varepsilon^2})$,
where $n$ is the number of points.


title:
Vanishing Viscosity Limit For the 3D Nonhomogeneous Incompressible
  Navier-Stokes Equations With a Slip Boundary Condition

abstract:
  In this paper, we investigate the vanishing viscosity limit for the 3D
nonhomogeneous incompressible Navier-Stokes equations with a slip boundary
condition. We establish the local well-posedness of the strong solutions for
initial boundary value problems for such systems. Furthermore, the vanishing
viscosity limit process is established and a strong rate of convergence is
obtained as the boundary of the domain is flat. In addition, it is needed to
add some additional condition for density to match well the boundary condition.


title:
Higher Derivative Theories for Interacting Massless Gravitons in
  Minkowski Spacetime

abstract:
  We study a novel class of higher derivative theories for interacting massless
gravitons in Minkowski spacetime. These theories were first discussed by Wald
decades ago, and are characterized by scattering amplitudes essentially
different from general relativity and many of its modifications. We discuss
various aspects of these higher derivative theories, including the Lagrangian
construction, violation of asymptotic causality, scattering amplitudes,
non-renormalization, and possible implications on emergent gravitons from
condensed matter systems.


title: The local spiral structure of the Milky Way

abstract:
  The nature of the spiral structure of the Milky Way has long been debated.
Only in the last decade have astronomers been able to accurately measure
distances to a substantial number of high-mass star-forming regions, the
classic tracers of spiral structure in galaxies. We report distance
measurements at radio wavelengths using the Very Long Baseline Array for eight
regions of massive star formation near the Local spiral arm of the Milky Way.
Combined with previous measurements, these observations reveal that the Local
Arm is larger than previously thought, and both its pitch angle and star
formation rate are comparable to those of the Galaxy's major spiral arms, such
as Sagittarius and Perseus. Toward the constellation Cygnus, sources in the
Local Arm extend for a great distance along our line of sight and roughly along
the solar orbit. Because of this orientation, these sources cluster both on the
sky and in velocity to form the complex and long enigmatic Cygnus X region. We
also identify a spur that branches between the Local and Sagittarius spiral
arms.


title: Deep unsupervised learning through spatial contrasting

abstract:
  Convolutional networks have marked their place over the last few years as the
best performing model for various visual tasks. They are, however, most suited
for supervised learning from large amounts of labeled data. Previous attempts
have been made to use unlabeled data to improve model performance by applying
unsupervised techniques. These attempts require different architectures and
training methods. In this work we present a novel approach for unsupervised
training of Convolutional networks that is based on contrasting between spatial
regions within images. This criterion can be employed within conventional
neural networks and trained using standard techniques such as SGD and
back-propagation, thus complementing supervised methods.


title:
Stueckelberg massive electromagnetism in de Sitter and anti-de Sitter
  spacetimes: Two-point functions and renormalized stress-energy tensors

abstract:
  By considering Hadamard vacuum states, we first construct the two-point
functions associated with Stueckelberg massive electromagnetism in de Sitter
and anti-de Sitter spacetimes. Then, from the general formalism developed in
[A. Belokogne and A. Folacci, Phys. Rev. D \textbf{93}, 044063 (2016)], we
obtain an exact analytical expression for the vacuum expectation value of the
renormalized stress-energy tensor of the massive vector field propagating in
these maximally symmetric spacetimes.


title: Phonon assisted resonant tunnelling and its phonons control

abstract:
  We observe a series of sharp resonant features in the tunnelling differential
conductance of InAs quantum dots. We found that dissipative quantum tunnelling
has a strong influence on the operation of nano-devices. Because of such
tunnelling the current-voltage characteristics of tunnel contact created
between atomic force microscope tip and a surface of InAs/GaAs quantum dots
display many interesting peaks. We found that the number, position, and heights
of these peaks are associated with the phonon modes involved. To describe the
found effect we use a quasi-classical approximation. There the tunnelling
current is related to a creation of a dilute instanton-anti-instanton gas. Our
experimental data are well described with exactly solvable model where one
charged particle is weakly interacting with two promoting phonon modes
associated with external medium. We conclude that the characteristics of the
tunnel nanoelectronic devices can thus be controlled by a proper choice of
phonons existing in materials, which are involved.


title:
HNP3: A Hierarchical Nonparametric Point Process for Modeling Content
  Diffusion over Social Media

abstract:
  This paper introduces a novel framework for modeling temporal events with
complex longitudinal dependency that are generated by dependent sources. This
framework takes advantage of multidimensional point processes for modeling time
of events. The intensity function of the proposed process is a mixture of
intensities, and its complexity grows with the complexity of temporal patterns
of data. Moreover, it utilizes a hierarchical dependent nonparametric approach
to model marks of events. These capabilities allow the proposed model to adapt
its temporal and topical complexity according to the complexity of data, which
makes it a suitable candidate for real world scenarios. An online inference
algorithm is also proposed that makes the framework applicable to a vast range
of applications. The framework is applied to a real world application, modeling
the diffusion of contents over networks. Extensive experiments reveal the
effectiveness of the proposed framework in comparison with state-of-the-art
methods.


title: The large $k$-term progression-free sets in $\mathbb{Z}_q^n$

abstract:
  Let $k$ and $n$ be fixed positive integers. For each prime power $q\geqslant
k\geqslant 3$, we show that any subset $A\subseteq \mathbb{Z}_q^n$ free of
$k$-term arithmetic progressions has size $|A|\leqslant c_k(q)^n$ with a
constant $c_k(q)$ that can be expressed explicitly in terms of $k$ and $q$. As
a consequence, we can take $c_k(q)=0.8415q$ for sufficiently large $q$ and
arbitrarily fixed $k\geq 3$.


title: Battling the Digital Forensic Backlog through Data Deduplication

abstract:
  In everyday life. Technological advancement can be found in many facets of
life, including personal computers, mobile devices, wearables, cloud services,
video gaming, web-powered messaging, social media, Internet-connected devices,
etc. This technological influence has resulted in these technologies being
employed by criminals to conduct a range of crimes -- both online and offline.
Both the number of cases requiring digital forensic analysis and the sheer
volume of information to be processed in each case has increased rapidly in
recent years. As a result, the requirement for digital forensic investigation
has ballooned, and law enforcement agencies throughout the world are scrambling
to address this demand. While more and more members of law enforcement are
being trained to perform the required investigations, the supply is not keeping
up with the demand. Current digital forensic techniques are arduously
time-consuming and require a significant amount of man power to execute. This
paper discusses a novel solution to combat the digital forensic backlog. This
solution leverages a deduplication-based paradigm to eliminate the
reacquisition, redundant storage, and reanalysis of previously processed data.


title: Spin galvanic effect at the conducting SrTiO3 surfaces

abstract:
  The (001) surface of SrTiO3 were transformed from insulating to conducting
after Ar+ irradiation, producing a quasi two-dimensional electron gas (2DEG).
This conducting surface layer can introduce Rashba spin orbital coupling due to
the broken inversion symmetry normal to the plane. The spin splitting of such a
surface has recently been demonstrated by magneto-resistance and angular
resolved photoemission spectra measurements. Here we present experiments
evidencing a large spin-charge conversion at the surface. We use spin pumping
to inject a spin current from NiFe film into the surface, and measure the
resulting charge current. The results indicate that the Rashba effect at the
surface can be used for efficient charge-spin conversion, and the large
efficiency is due to the multi-d-orbitals and surface corrugation. It holds
great promise in oxide spintronics.


title: The effect of Jupiter oscillations on Juno gravity measurements

abstract:
  Seismology represents a unique method to probe the interiors of giant
planets. Recently, Saturn's f-modes have been indirectly observed in its rings,
and there is strong evidence for the detection of Jupiter global modes by means
of ground-based, spatially-resolved, velocimetry measurements. We propose to
exploit Juno's extremely accurate radio science data by looking at the gravity
perturbations that Jupiter's acoustic modes would produce. We evaluate the
perturbation to Jupiter's gravitational field using the oscillation spectrum of
a polytrope with index 1 and the corresponding radial eigenfunctions. We show
that Juno will be most sensitive to the fundamental mode ($n=0$), unless its
amplitude is smaller than 0.5 cm/s, i.e. 100 times weaker than the $n \sim\ 4 -
11$ modes detected by spatially-resolved velocimetry. The oscillations yield
contributions to Juno's measured gravitational coefficients similar to or
larger than those expected from shallow zonal winds (extending to depths less
than 300 km). In the case of a strong f-mode (radial velocity $\sim$ 30 cm/s),
these contributions would become of the same order as those expected from deep
zonal winds (extending to 3000 km), especially on the low degree zonal
harmonics, therefore requiring a new approach to the analysis of Juno data.


title:
Salt Reconstruction in Full Waveform Inversion with a Parametric
  Level-Set Method

abstract:
  Seismic full-waveform inversion tries to estimate subsurface medium
parameters from seismic data. Areas with subsurface salt bodies are of
particular interest because they often have hydrocarbon reservoirs on their
sides or underneath. Accurate reconstruction of their geometry is a challenge
for current techniques. This paper presents a parametric level-set method for
the reconstruction of salt-bodies in seismic full-waveform inversion. We split
the subsurface model in two parts: a background velocity model and the salt
body with known velocity but undetermined shape. The salt geometry is
represented by a level-set function that evolves during the inversion. We
choose radial basis functions to represent the level-set function, leading to
an optimization problem with a modest number of parameters. A common problem
with level-set methods is to fine tune the width of the level-set boundary for
optimal sensitivity. We propose a robust algorithm that dynamically adapts the
width of the level-set boundary to ensure faster convergence. Tests on a suite
of idealized salt geometries show that the proposed method is stable against a
modest amount of noise. We also extend the method to joint inversion of both
the background velocity model and the salt-geometry.


title:
Chaos and correlated avalanches in excitatory neural networks with
  synaptic plasticity

abstract:
  A collective chaotic phase with power law scaling of activity events is
observed in a disordered mean field network of purely excitatory leaky
integrate-and-fire neurons with short-term synaptic plasticity. The dynamical
phase diagram exhibits two transitions from quasi-synchronous and asynchronous
regimes to the nontrivial, collective, bursty regime with avalanches. In the
homogeneous case without disorder, the system synchronizes and the bursty
behavior is reflected into a doubling-period transition to chaos for a two
dimensional discrete map. Numerical simulations show that the bursty chaotic
phase with avalanches exhibits a spontaneous emergence of time correlations and
enhanced Kolmogorov complexity. Our analysis reveals a mechanism for the
generation of irregular avalanches that emerges from the combination of
disorder and deterministic underlying chaotic dynamics.

categories: cond-mat.dis-nn cond-mat.stat-mech nlin.AO q-bio.NC


title:
Asynchronous Distributed Execution Of Fixpoint-Based Computational
  Fields

abstract:
  Coordination is essential for dynamic distributed systems whose components
exhibit interactive and autonomous behaviors. Spatially distributed, locally
interacting, propagating computational fields are particularly appealing for
allowing components to join and leave with little or no overhead. Computational
fields are a key ingredient of aggregate programming, a promising software
engineering methodology particularly relevant for the Internet of Things. In
our approach, space topology is represented by a fixed graph-shaped field,
namely a network with attributes on both nodes and arcs, where arcs represent
interaction capabilities between nodes. We propose a SMuC calculus where
mu-calculus- like modal formulas represent how the values stored in neighbor
nodes should be combined to update the present node. Fixpoint operations can be
understood globally as recursive definitions, or locally as asynchronous
converging propagation processes. We present a distributed implementation of
our calculus. The translation is first done mapping SMuC programs into normal
form, purely iterative programs and then into distributed programs. Some key
results are presented that show convergence of fixpoint computations under fair
asynchrony and under reinitialization of nodes. The first result allows nodes
to proceed at different speeds, while the second one provides robustness
against certain kinds of failure. We illustrate our approach with a case study
based on a disaster recovery scenario, implemented in a prototype simulator
that we use to evaluate the performance of a recovery strategy.


title: The Role of AGB Stars Feedback in Sustaining Galaxy Evolution

abstract:
  We have conducted a near-infrared monitoring campaign at the UK InfraRed
Telescope, of the Local Group spiral galaxy M33. The main aim was to identify
stars in the very final stage of their evolution, and for which the luminosity
is more directly related to the birth mass than the more numerous less--evolved
giant stars that continue to increase in luminosity. In first instance, only
the central square kiloparsec were monitored and analysed, with the UIST
camera. Photometry was obtained for 18,398 stars; of these 812 stars were found
to be variable, most of which are asymptotic giant branch (AGB) stars. We
constructed the birth mass function and hence derived the star formation
history. These stars are also important dust factories. We measure their dust
production rates from a combination of our data with Spitzer Space Telescope
mid-IR photometry. The mass loss rates are seen to increase with increasing
strength of pulsation and with increasing bolometric luminosity. We construct a
2D map of the mass return rate, showing a radial decline but also local
enhancements due to the concentration of red supergiants. We conclude that star
formation in the central region of M33 can only be sustained if gas is accreted
from further out in the disc or from circum--galactic regions. By using data of
wide-field camera (WFCAM), the campaign was expanded to cover two orders of
magnitude larger area, comprising the disc of M33 and its spiral arms.
Photometry was obtained for 403,734 stars; of these 4643 stars were found to be
variable. We here present the star formation history across the disc of M33.


title: Hadronic modeling of TeV AGN: gammas and neutrinos

abstract:
  Blazar emission models are usually divided into two big families, leptonic
and hadronic, according to the particles which are responsible for the
gamma-ray component of their spectral energy distributions. Even though
leptonic models have been successful in explaining the gamma-ray emission from
most blazars, hadronic models still present an intriguing alternative. They
have the unique advantage to link the emission of photons, neutrinos, and
cosmic rays from the astrophysical source. We have developed a stationary
one-zone lepto-hadronic code to model the emission from blazars in both
leptonic and hadronic scenarios. In this contribution we focus on hadronic
modeling of a few selected TeV blazars of the BL Lac type and the radio galaxy
Centaurus A detected by Cherenkov telescopes. We study in particular their
associated neutrino emission, for different hadronic scenarios, and how it
compares to the sensitivity of current neutrino detectors.


title: XVA at the Exercise Boundary

abstract:
  XVA is a material component of a trade valuation and hence it must impact the
decision to exercise options within a given netting set. This is true for both
unsecured trades and secured / cleared trades where KVA and MVA play a material
role even if CVA and FVA do not. However, this effect has frequently been
ignored in XVA models and indeed in exercise decisions made by option owners.
This paper describes how XVA impacts the exercise decision and how this can be
readily evaluated using regression techniques (Longstaff and Schwartz 2001).
The paper then assesses the materiality of the impact of XVA at the exercise
boundary on swaption examples.


title:
Square-root algorithms for maximum correntropy estimation of linear
  discrete-time systems in presence of non-Gaussian noise

abstract:
  Recent developments in the realm of state estimation of stochastic dynamic
systems in the presence of non-Gaussian noise have induced a new methodology
called the maximum correntropy filtering. The filters designed under the
maximum correntropy criterion (MCC) utilize a similarity measure (or
correntropy) between two random variables as a cost function. They are shown to
improve the estimators' robustness against outliers or impulsive noises. In
this paper we explore the numerical stability of linear filtering technique
proposed recently under the MCC approach. The resulted estimator is called the
maximum correntropy criterion Kalman filter (MCC-KF). The purpose of this study
is two-fold. First, the previously derived MCC-KF equations are revise and the
related Kalman-like equality conditions are proved. Based on this theoretical
finding, we improve the MCC-KF technique in the sense that the new method
possesses a better estimation quality with the reduced computational cost
compared with the previously proposed MCC-KF variant. Second, we devise some
square-root implementations for the newly-designed improved estimator. The
square-root algorithms are well known to be inherently more stable than the
conventional Kalman-like implementations, which process the full error
covariance matrix in each iteration step of the filter. Additionally, following
the latest achievements in the KF community, all square-root algorithms are
formulated here in the so-called array form. All the MCC-KF variants developed
in this paper are demonstrated to outperform the previously proposed MCC-KF
version in two numerical examples.


title:
Spectral Changes in the Hyperluminous Pulsar in NGC 5907 as a Function
  of Super-Orbital Phase

abstract:
  We present broad-band, multi-epoch X-ray spectroscopy of the pulsating
ultra-luminous X-ray source (ULX) in NGC 5907. Simultaneous XMM-Newton and
NuSTAR data from 2014 are best described by a multi-color black-body model with
a temperature gradient as a function of accretion disk radius significantly
flatter than expected for a standard thin accretion disk (T(r) ~ r^{-p}, with
p=0.608^{+0.014}_{-0.012}). Additionally, we detect a hard power-law tail at
energies above 10 keV, which we interpret as being due to Comptonization. We
compare this observation to archival XMM-Newton, Chandra, and NuSTAR data from
2003, 2012, and 2013, and investigate possible spectral changes as a function
of phase over the 78d super-orbital period of this source. We find that
observations taken around phases 0.3-0.4 show very similar temperature
profiles, even though the observed flux varies significantly, while one
observation taken around phase 0 has a significantly steeper profile. We
discuss these findings in light of the recent discovery that the compact object
is a neutron star and show that precession of the accretion disk or the neutron
star can self-consistently explain most observed phenomena.


title:
Hysteresis and Duration Dependence of Financial Crises in the US:
  Evidence from 1871-2016

abstract:
  This study analyses the duration dependence of events that trigger volatility
persistence in stock markets. Such events, in our context, are monthly spells
of contiguous price decline or negative returns for the S&P500 stock market
index over the last 145 years. Factors known to affect the duration of these
spells are the magnitude or intensity of the price decline, long-term interest
rates and economic recessions, among others. The result of interest is the
conditional probability of ending a spell of consecutive months over which
stock market returns remain negative. In this study, we rely on continuous time
survival models in order to investigate this question. Several specifications
were attempted, some of which under the proportional hazards assumption and
others under the accelerated failure time assumption. The best fit of the
various models endeavored was obtained for the log-normal distribution. This
distribution yields a non-monotonic hazard function that increases up to a
maximum and then decreases. The peak is achieved 2-3 months after the spells
onset with a hazard of around 0.9 or higher; this hazard then decays
asymptotically to zero. Spells duration increase during recessions, when
interest rate rises and when price declines are more intense. The main
conclusion is that short spells of negative returns appear to be mainly
frictional while long spells become structural and trigger hysteresis effects
after an initial period of adjustment. Although in line with our expectations,
these results may be of some importance for policy-makers.


title: Non-Koszul quadratic Gorenstein toric rings

abstract:
  Koszulness of Gorenstein quadratic algebras of small socle degree is studied.
In this note, we construct non-Koszul Gorenstein quadratic toric ring such that
its socle degree is more than 3 by using stable set polytopes.


title:
Limit Order Strategic Placement with Adverse Selection Risk and the Role
  of Latency

abstract:
  This paper is split in three parts: first we use labelled trade data to
exhibit how market participants accept or not transactions via limit orders as
a function of liquidity imbalance; then we develop a theoretical stochastic
control framework to provide details on how one can exploit his knowledge on
liquidity imbalance to control a limit order. We emphasis the exposure to
adverse selection, of paramount importance for limit orders. For a participant
buying using a limit order: if the price has chances to go down the probability
to be filled is high but it is better to wait a little more before the trade to
obtain a better price. In a third part we show how the added value of
exploiting a knowledge on liquidity imbalance is eroded by latency: being able
to predict future liquidity consuming flows is of less use if you have not
enough time to cancel and reinsert your limit orders. There is thus a rational
for market makers to be as fast as possible as a protection to adverse
selection. Thanks to our optimal framework we can measure the added value of
latency to limit orders placement.
  To authors' knowledge this paper is the first to make the connection between
empirical evidences, a stochastic framework for limit orders including adverse
selection, and the cost of latency. Our work is a first stone to shed light on
the roles of latency and adverse selection for limit order placement, within an
accurate stochastic control framework.


title:
Understanding Epileptiform After-Discharges as Rhythmic Oscillatory
  Transients

abstract:
  Electro-cortical activity in patients with epilepsy may show abnormal
rhythmic transients in response to stimulation. Even when using the same
stimulation parameters in the same patient, wide variability in the duration of
transient response has been reported. These transients have long been
considered important for the mapping of the excitability levels in the
epileptic brain but their dynamic mechanism is still not well understood.
  To understand the occurrence of abnormal transients dynamically, we use a
thalamo-cortical neural population model of epileptic spike-wave activity and
study the interaction between slow and fast subsystems.
  In a reduced version of the thalamo-cortical model, slow wave oscillations
arise from a fold of cycles (FoC) bifurcation. This marks the onset of a region
of bistability between a high amplitude oscillatory rhythm and the background
state. In vicinity of the bistability in parameter space, the model has
excitable dynamics, showing prolonged rhythmic transients in response to
suprathreshold pulse stimulation. We analyse the state space geometry of the
bistable and excitable states, and find that the rhythmic transient arises when
the impending FoC bifurcation deforms the state space and creates an area of
locally reduced attraction to the fixed point. This area essentially allows
trajectories to dwell there before escaping to the stable steady state, thus
creating rhythmic transients. In the full thalamo-cortical model, we find a
similar FoC bifurcation structure.
  Based on the analysis, we propose an explanation of why stimulation induced
epileptiform activity may vary between trials, and predict how the variability
could be related to ongoing oscillatory background activity.


title:
Observation of charge-dependent azimuthal correlations in pPb collisions
  and its implication for the search for the chiral magnetic effect

abstract:
  Charge-dependent azimuthal particle correlations with respect to the
second-order event plane in pPb and PbPb collisions at a nucleon-nucleon
center-of-mass energy of 5.02 TeV have been studied with the CMS experiment at
the LHC. The measurement is performed with a three-particle correlation
technique, using two particles with the same or opposite charge within the
pseudorapidity range abs(eta) < 2.4, and a third particle measured in the
hadron forward calorimeters (4.4 < abs(eta) < 5). The observed differences
between the same and opposite sign correlations, as functions of multiplicity
and eta gap between the two charged particles, are of similar magnitude in pPb
and PbPb collisions at the same multiplicities. These results pose a challenge
for the interpretation of charge-dependent azimuthal correlations in heavy ion
collisions in terms of the chiral magnetic effect.


title: Particle Identification at Belle II

abstract:
  We report on the charged particle identification (PID) systems for the
upcoming Belle II experiment. The time of propagation counter in the central
region and the proximity focusing ring imaging Cherenkov counters with aerogel
radiator in the forward region will be used as the PID devices. They are
expected to provide a kaon identification efficiency of more than 94% at a low
pion misidentification probability of 4%. The motivation for the upgrade,
method, and status of both systems are discussed.


title: Sonneberg Sky Patrol Archive - Photometric Analysis

abstract:
  The Sonneberg Sky Patrol archive so far has not yet been analyzed
systematically. In this paper we present first steps towards an automated
photometric analysis aiming at the search for variable stars and transient
phenomena like novae. Early works on the sky patrol plates showed that
photometric accuracy can be enhanced with fitting algorithms. The procedure
used was a manually supported click-and-fit-routine, not suitable for automatic
analysis of vast amount of photographic plates. We will present our progress on
deconvolution of overlapping sources on the plates and compare photometric
analysis using different methods. Our goal is to get light curves of sufficient
quality from sky patrol plates, which can be classified with machine learning
algorithms. The development of an automated scheme for finding transient events
is in progress and the first results are very promising.


title: Hans Wolter - a pioneer of applied optics

abstract:
  Applied optics was one of the major topics Hans Walter was engaged in during
his scientific life. He contributed to the understanding of optical properties
of thin films, which could be used to design coating layers to improve the
properties of optical and other surfaces. He developed the theoretical
description of the basic principles of phase-contrast, schlieren and
interference optics applied to enhance low contrast details and to increase the
resolution in studies of biological samples. And last, but not least, Hans
Wolter proposed an optical system of two grazing--incidence mirrors for use in
an X--ray imaging microscope. A microscope using such an optics never was put
into practice, but the optical design turned out to be well suited for
telescopes.


title:
A sufficient condition for global existence of solutions to a
  generalized derivative nonlinear Schr\"{o}dinger equation

abstract:
  We give a sufficient condition for global existence of the solutions to a
generalized derivative nonlinear Schr\"{o}dinger equation (gDNLS) by a
variational argument. The variational argument is applicable to a cubic
derivative nonlinear Schr\"{o}dinger equation (DNLS). For (DNLS), Wu proved
that the solution with the initial data $u_0$ is global if $\left\Vert u_0
\right\Vert_{L^2}^2<4\pi$ by the sharp Gagliardo--Nirenberg inequality in the
paper "Global well-posedness on the derivative nonlinear Schr\"odinger
equation", Analysis & PDE 8 (2015), no. 5, 1101--1112. The variational argument
gives us another proof of the global existence for (DNLS). Moreover, by the
variational argument, we can show that the solution to (DNLS) is global if the
initial data $u_0$ satisfies that $\left\Vert u_0 \right\Vert_{L^2}^2=4\pi$ and
the momentum $P(u_0)$ is negative.


title:
Balayage for Riesz kernels with application to potential theory for the
  associated Green kernels

abstract:
  We study properties of the $\alpha$-Green kernel $g_D^\alpha$ of order
$0<\alpha\leqslant2$ for a domain $D\subset\mathbb R^n$, $n\geqslant3$. This
kernel is associated with the $\alpha$-Riesz kernel $|x-y|^{\alpha-n}$,
$x,y\in\mathbb R^n$, in a manner particularly well known in the case
$\alpha=2$. Besides the usual principles of potential theory, we establish for
the $\alpha$-Green kernel the property of consistency. This allows us to prove
the completeness of the cone of positive measures $\mu$ on $D$ with finite
energy $g_D^\alpha(\mu,\mu):=\iint g_D^\alpha(x,y)\,d\mu(x)\,d\mu(y)$ in the
topology defined by the energy norm
$\|\mu\|_{g_D^\alpha}=\sqrt{g_D^\alpha(\mu,\mu)}$, as well as the existence of
the $\alpha$-Green equilibrium measure for a relatively closed set in $D$ of
finite $\alpha$-Green capacity. The main tool is a generalization of Cartan's
theory of balayage (sweeping) for the Newtonian kernel to the $\alpha$-Riesz
kernels with $0<\alpha<2$.


title: Structural Phase Stability in Fluorinated Calcium Hydride

abstract:
  In order to improve the hydrogen storage properties of calcium hydride
(CaH2), we have tuned its thermodynamical properties through fluorination.
Using ab-initio total energy calculations based on density functional theory,
the structural stability, electronic structure and chemical bonding of CaH2-xFx
systems are investigated. The phase transition of fluorinated systems from
orthorhombic to cubic structure has been observed at 18% fluorine doped CaH2.
The phase stability analysis shows that CaH2-xFx systems are highly stable and
the stability is directly correlating with their ionicity. Density of states
(DOS) plot reveals that CaH2-xFx systems are insulators. Partial DOS and charge
density analyses conclude that these systems are governed by ionic bonding. Our
results show that H closer to F can be removed more easily than that far away
from F and this is due to disproportionation induced in the bonding interaction
by fluorination.