title:
On the Connections Between Surficial Processes and Stratigraphy in River
  Deltas

abstract:
  We explore connections between surficial deltaic processes (e.g. avulsion,
deposition) and the stratigraphic record using a simple numerical model of
delta-plain evolution, with the aim of constraining these connections and thus
improving prediction of subsurface features. The model represents channel
dynamics using a simple but flexible cellular approach, and is unique in that
it explicitly includes backwater effects that are known to be important in
low-gradient channel networks. The patterns of channel deposits in the
stratigraphic record vary spatially due to variation in avulsion statistics
with radial distance from the delta's source of water and sediment. We
introduce channel residence time as an important statistical measure of the
surface channel kinematics. The model suggests that the mean channel residence
time anywhere within the delta is nicely described by a power law distribution
showing a cutoff that depends on radial distance. Thicknesses of channel
deposits are not uniquely determined by the residence time of channelization.
The channel residence time distributions at given radial distances from the
source are found to be approximately lognormally distributed, a finding
consistent with the scale-dependent radial structure of channel deposits in the
stratigraphic record.


title: Precession Relaxation of Viscoelastic Oblate Rotators

abstract:
  Perturbations of all sorts destabilise the rotation of a small body and leave
it in a non-principal spin state. In such a state, the body experiences
alternating stresses generated by the inertial forces. This yields nutation
relaxation, i.e., evolution of the spin towards the principal rotation about
the maximal-inertia axis. Knowledge of the timescales needed to damp the
nutation is crucial in studies of small bodies' dynamics. In the literature
hitherto, nutation relaxation has always been described with aid of an
empirical quality factor $\,Q\,$ introduced to parameterise the energy
dissipation rate.
  Among the drawbacks of this approach was its inability to describe the
dependence of the relaxation rate upon the current nutation angle. This
inability stemmed from our lack of knowledge of the quality factor's dependence
on the forcing frequency. In this article, we derive our description of
nutation damping directly from the rheological law obeyed by the material. This
renders us the nutation damping rate as a function of the current nutation
angle, as well as of the shape and the rheological parameters of the body. In
contradistinction from the approach based on an empirical $\,Q\,$-factor, our
development gives a zero damping rate in the spherical-shape limit. Our method
is generic and applicable to any shape and to any linear rheological law.
However, to simplify the developments, here we consider a dynamically oblate
rotator with a Maxwell rheology.


title: Ruelle zeta function at zero for surfaces

abstract:
  We show that the Ruelle zeta function for a negatively curved oriented
surface vanishes at zero to the order given by the absolute value of the Euler
characteristic. This result was previously known only in constant curvature.


title: A two-stage learning method for protein-protein interaction prediction

abstract:
  In this paper, a new method for PPI (proteinprotein interaction) prediction
is proposed. In PPI prediction, a reliable and sufficient number of training
samples is not available, but a large number of unlabeled samples is in hand.
In the proposed method, the denoising auto encoders are employed for learning
robust features. The obtained robust features are used in order to train a
classifier with a better performance. The experimental results demonstrate the
capabilities of the proposed method.
  Protein-protein interaction; Denoising auto encoder;Robust features;
Unlabelled data;


title: Relation between halo spin and cosmic web filaments at z=3

abstract:
  We investigate the spin evolution of dark matter haloes and their dependence
on the number of connected filaments from the cosmic web at high redshift
(spin-filament relation hereafter). To this purpose, we have simulated $5000$
haloes in the mass range $5\times10^{9}h^{-1}M_{\odot}$ to
$5\times10^{11}h^{-1}M_{\odot}$ at $z=3$ in cosmological N-body simulations. We
confirm the relation found by Prieto et al. 2015 where haloes with fewer
filaments have larger spin. We also found that this relation is more
significant for higher halo masses, and for haloes with a passive (no major
mergers) assembly history. Another finding is that haloes with larger spin or
with fewer filaments have their filaments more perpendicularly aligned with the
spin vector. Our results point to a picture in which the initial spin of haloes
is well described by tidal torque theory and then gets subsequently modified in
a predictable way because of the topology of the cosmic web, which in turn is
given by the currently favoured LCDM model. Our spin-filament relation is a
prediction from LCDM that could be tested with observations.


title:
An Algorithm for Real-Time Optimal Photocurrent Estimation including
  Transient Detection for Resource-Constrained Imaging Applications

abstract:
  Mega-pixel charge-integrating detectors are common in near-IR imaging
applications. Optimal signal-to-noise ratio estimates of the photocurrents,
which are particularly important in the low-signal regime, are produced by
fitting linear models to sequential reads of the charge on the detector.
Algorithms that solve this problem have a long history, but can be
computationally intensive. Furthermore, the cosmic ray background is
appreciable for these detectors in Earth orbit, particularly above the Earth's
magnetic poles and the South Atlantic Anomaly, and on-board reduction routines
must be capable of flagging affected pixels. In this paper we present an
algorithm that generates optimal photocurrent estimates and flags random
transient charge generation from cosmic rays, and is specifically designed to
fit on a computationally restricted platform. We take as a case study the
Spectro-Photometer for the History of the Universe, Epoch of Reionization, and
Ices Explorer (SPHEREx), a NASA Small Explorer astrophysics experiment concept,
and show that the algorithm can easily fit in the resource-constrained
environment of such a restricted platform. Detailed simulations of the input
astrophysical signals and detector array performance are used to characterize
the fitting routines in the presence of complex noise properties and charge
transients. We use both Hubble Space Telescope Wide Field Camera-3 and
Wide-field Infrared Survey Explorer to develop an empirical understanding of
the susceptibility of near-IR detectors in low earth orbit and build a model
for realistic cosmic ray energy spectra and rates. We show that our algorithm
generates an unbiased estimate of the true photocurrent that is identical to
that from a standard line fitting package, and characterize the rate, energy,
and timing of both detected and undetected transient events.


title:
Non-Gaussian bivariate modelling with application to atmospheric
  trace-gas inversion

abstract:
  Atmospheric trace-gas inversion is the procedure by which the sources and
sinks of a trace gas are identified from observations of its mole fraction at
isolated locations in space and time. This is inherently a spatio-temporal
bivariate inversion problem, since the mole-fraction field evolves in space and
time and the flux is also spatio-temporally distributed. Further, the bivariate
model is likely to be non-Gaussian since the flux field is rarely Gaussian.
Here, we use conditioning to construct a non-Gaussian bivariate model, and we
describe some of its properties through auto- and cross-cumulant functions. A
bivariate non-Gaussian, specifically trans-Gaussian, model is then achieved
through the use of Box--Cox transformations, and we facilitate Bayesian
inference by approximating the likelihood in a hierarchical framework.
Trace-gas inversion, especially at high spatial resolution, is frequently
highly sensitive to prior specification. Therefore, unlike conventional
approaches, we assimilate trace-gas inventory information with the
observational data at the parameter layer, thus shifting prior sensitivity from
the inventory itself to its spatial characteristics (e.g., its spatial length
scale). We demonstrate the approach in controlled-experiment studies of methane
inversion, using fluxes extracted from inventories of the UK and Ireland and of
Northern Australia.


title:
High sensitivity phonon-mediated kinetic inductance detector with
  combined amplitude and phase read-out

abstract:
  The development of wide-area cryogenic light detectors with good energy
resolution is one of the priorities of next generation bolometric experiments
searching for rare interactions, as the simultaneous read-out of the light and
heat signals enables background suppression through particle identification.
Among the proposed technological approaches for the phonon sensor, the
naturally-multiplexed Kinetic Inductance Detectors (KIDs) stand out for their
excellent intrinsic energy resolution and reproducibility. To satisfy the large
surface requirement (several cm$^2$) KIDs are deposited on an insulating
substrate that converts the impinging photons into phonons. A fraction of
phonons is absorbed by the KID, producing a signal proportional to the energy
of the original photons. The potential of this technique was proved by the
CALDER project, that reached a baseline resolution of 154$\pm$7 eV RMS by
sampling a 2$\times$2 cm$^2$ Silicon substrate with 4 Aluminum KIDs. In this
paper we present a prototype of Aluminum KID with improved geometry and quality
factor. The design improvement, as well as the combined analysis of amplitude
and phase signals, allowed to reach a baseline resolution of 82$\pm$4 eV by
sampling the same substrate with a single Aluminum KID.


title: iSURF: A family of infinite-time surface flux methods

abstract:
  The computation and analysis of photoelectron spectra (PES) is a fundamental
technique in atomic and molecular physics to study the structural and dynamical
properties of a target system, and to gain insight into the process of its
ionization. Since the first numerical solutions of the time-dependent
Schr\"odinger equation, numerous methods have been developed to extract PES
from the calculated wave functions. However, most of these methods have severe
limitations or are computationally very demanding. Here we present a new family
of methods, based on the ideas of the so-called analytical Volkov continuation,
or time-dependent surface flux ([Ermolaev, A. M. et al. Phys. Rev. A 60, 4831
(1999), Ermolaev, A. M. et al. Phys. Rev. A 62, 015401 (2000), Tao L. and
Scrinzi A. New Journal of Physics 14, 013021 (2012)]), that allows one to
obtain fully-converged PES at the end of the laser pulse using either Volkov
states or the exact scattering-states, and that has been implemented in the
Time Dependent Schr\"odinger Equation (TDSE) solver ([Patchkovskii S. and
Muller H. G., Computer Physics Communications 199, 153 (2016)]).


title:
Regression-based reduced-order models to predict transient thermal
  output for enhanced geothermal systems

abstract:
  The goal of this paper is to assess the utility of Reduced-Order Models
(ROMs) developed from 3D physics-based models for predicting transient thermal
power output for an enhanced geothermal reservoir while explicitly accounting
for uncertainties in the subsurface system and site-specific details. Numerical
simulations are performed based on Latin Hypercube Sampling (LHS) of model
inputs drawn from uniform probability distributions. Key sensitive parameters
are identified from these simulations, which are fracture zone permeability,
well/skin factor, bottom hole pressure, and injection flow rate. The inputs for
ROMs are based on these key sensitive parameters. The ROMs are then used to
evaluate the influence of subsurface attributes on thermal power production
curves. The resulting ROMs are compared with field-data and the detailed
physics-based numerical simulations. We propose three different ROMs with
different levels of model parsimony, each describing key and essential features
of the power production curves. ROM-1 is able to accurately reproduce the power
output of numerical simulations for low values of permeabilities and certain
features of the field-scale data, and is relatively parsimonious. ROM-2 is a
more complex model than ROM-1 but it accurately describes the field-data. At
higher permeabilities, ROM-2 reproduces numerical results better than ROM-1,
however, there is a considerable deviation at low fracture zone permeabilities.
ROM-3 is developed by taking the best aspects of ROM-1 and ROM-2 and provides a
middle ground for model parsimony. It is able to describe various features of
numerical simulations and field-data. From the proposed workflow, we
demonstrate that the proposed simple ROMs are able to capture various complex
features of the power production curves of Fenton Hill HDR system. For typical
EGS applications, ROM-2 and ROM-3 outperform ROM-1.


title:
Addressing the Regression Test Problem with Change Impact Analysis for
  Ada

abstract:
  The regression test selection problem--selecting a subset of a test-suite
given a change--has been studied widely over the past two decades. However, the
problem has seen little attention when constrained to high-criticality
developments and where a "safe" selection of tests need to be chosen. Further,
no practical approaches have been presented for the programming language Ada.
In this paper, we introduce an approach to solving the selection problem given
a combination of both static and dynamic data for a program and a change-set.
We present a change impact analysis for Ada that selects the safe set of tests
that need to be re-executed to ensure no regressions. We have implemented the
approach in the commercial, unit-testing tool VectorCAST, and validated it on a
number of open-source examples. On an example of a fully-functioning Ada
implementation of a DNS server (IRONSIDES), the experimental results show a 97%
reduction in test-case execution.


title:
Generic Behaviour of Strongly Reinforced Polya Urns : Convergence and
  Stability

abstract:
  We consider, as proposed and studied in Hofstad et.\ al.\ \cite{HHKR}, a
class of graph-based "interacting urn"-type Polya urn model inspired by
neuronal processing in the brain where a signal enters the brain at some
(randomly) chosen neuron and is transmitted to a (random) single neighbouring
neuron with a probability depending on the relative `efficiency' of the
synapses connecting the neurons, and in doing so the efficiency of the utilized
synapse is improved/reinforced. We study the structures (or architectures) and
relative efficiency of the neuronal networks that can arise from repeating this
process a very large number of times in a "strong reinforcement regime". Under
the most general conditions, we prove in the affirmative a part of the main
open conjecture in \cite{HHKR} i.e. the zero probability of convergence of the
corresponding "urn process" to any 'unstable' equilibrium. Under very generic
conditions, i.e., for an open and dense subset of parameters with full measure,
we also prove the full open conjecture by showing the finiteness of the
equilibrium set and hence the unit probability of convergence of the "urn
process" to some 'stable' equilibrium.


title: Glare suppression by coherence gated negation

abstract:
  Imaging of a weak target hidden behind a scattering medium can be
significantly confounded by glare. We report a method, termed coherence gated
negation (CGN), that uses destructive optical interference to suppress glare
and allow improved imaging of a weak target. As a demonstration, we show that
by permuting through a set range of amplitude and phase values for a reference
beam interfering with the optical field from the glare and target reflection,
we can suppress glare by an order of magnitude, even when the optical wavefront
is highly disordered. This strategy significantly departs from conventional
coherence gating methods in that CGN actively 'gates out' the unwanted optical
contributions while conventional methods 'gate in' the target optical signal.
We further show that the CGN method can outperform conventional coherence
gating image quality in certain scenarios by more effectively rejecting
unwanted optical contributions.


title: On Schur parameters in Steklov's problem

abstract:
  We study the recursion (aka Schur) parameters for monic polynomials
orthogonal on the unit circle with respect to a weight which provides negative
answer to the conjecture of Steklov.


title:
The Dynamical Relationship Between the Bar and Spiral Patterns of NGC
  1365

abstract:
  Theories that attempt to explain the dynamical relationship between bar and
spiral patterns in galactic disks make different predictions about the radial
profile of the pattern speed. These are tested for the H-alpha bar and spiral
patterns of NGC 1365. The radial profile of the pattern speed is measured by
fitting mathematical models that are based on the Tremaine-Weinberg method. The
results show convincing evidence for the bar rotating at a faster rate than the
spiral pattern, inconsistent with a global wave mode or a manifold. There is
evidence for mode coupling of the bar and spiral patterns at the overlap of
corotation and inner Lindblad resonances, but the evidence is unreliable and
inconsistent. The results are the most consistent with the bar and spiral
patterns being dynamically distinct features. The pattern speed of the bar
begins near an ILR and ends near the corotation resonance. The radial profile
of the pattern speed beyond the bar most closely resembles what is expected for
coupled spiral modes and tidal interactions.


title: String Inference from the LCP Array

abstract:
  The suffix array, perhaps the most important data structure in modern string
processing, is often augmented with the longest common prefix (LCP) array which
stores the lengths of the LCPs for lexicographically adjacent suffixes of a
string. Together the two arrays are roughly equivalent to the suffix tree with
the LCP array representing the tree shape.
  In order to better understand the combinatorics of LCP arrays, we consider
the problem of inferring a string from an LCP array, i.e., determining whether
a given array of integers is a valid LCP array, and if it is, reconstructing
some string or all strings with that LCP array. There are recent studies of
inferring a string from a suffix tree shape but using significantly more
information (in the form of suffix links) than is available in the LCP array.
  We provide two main results. (1) We describe two algorithms for inferring
strings from an LCP array when we allow a generalized form of LCP array defined
for a multiset of cyclic strings: a linear time algorithm for binary alphabet
and a general algorithm with polynomial time complexity for a constant alphabet
size. (2) We prove that determining whether a given integer array is a valid
LCP array is NP-complete when we require more restricted forms of LCP array
defined for a single cyclic or non-cyclic string or a multiset of non-cyclic
strings. The result holds whether or not the alphabet is restricted to be
binary. In combination, the two results show that the generalized form of LCP
array for a multiset of cyclic strings is fundamentally different from the
other more restricted forms.


title:
Liverpool Telescope follow-up of candidate electromagnetic counterparts
  during the first run of Advanced LIGO

abstract:
  The first direct detection of gravitational waves was made in late 2015 with
the Advanced LIGO detectors. By prior arrangement, a worldwide collaboration of
electromagnetic follow-up observers were notified of candidate gravitational
wave events during the first science run, and many facilities were engaged in
the search for counterparts. No counterparts were identified, which is in line
with expectations given that the events were classified as black hole - black
hole mergers. However these searches laid the foundation for similar follow-up
campaigns in future gravitational wave detector science runs, in which the
detection of neutron star merger events with observable electromagnetic
counterparts is much more likely. Three alerts were issued to the
electromagnetic collaboration over the course of the first science run, which
lasted from September 2015 to January 2016. Two of these alerts were associated
with the gravitational wave events since named GW150914 and GW151226. In this
paper we provide an overview of the Liverpool Telescope contribution to the
follow-up campaign over this period. Given the hundreds of square degree
uncertainty in the sky position of any gravitational wave event, efficient
searching for candidate counterparts required survey telescopes with large
(~degrees) fields-of-view. The role of the Liverpool Telescope was to provide
follow-up classification spectroscopy of any candidates. We followed candidates
associated with all three alerts, observing 1, 9 and 17 candidates
respectively. We classify the majority of the transients we observed as
supernovae.


title:
Spatial distribution and kinematics of the molecular material associated
  with $\eta$ Carinae

abstract:
  Single-dish sub-millimeter observations have recently revealed the existence
of a substantial, chemically peculiar, molecular gas component located in the
innermost circumstellar environment of the very massive luminous blue variable
star $\eta$ Carinae. Here, we present 5$"$-resolution interferometric
observations of the 1$\rightarrow$0 rotational transition of hydrogen cyanide
(HCN) obtained with the Australia Telescope Compact Array (ATCA) toward this
star. The emission is concentrated in the central few arcseconds around $\eta$
Carinae and shows a clear 150 km s$^{-1}$ velocity gradient running from
west-north-west (blue) to east-south-east (red). Given the extent, location,
and kinematics of this molecular material, we associate it with the complex of
dusty arcs and knots seen in mid-infrared emission near the center of the
Homunculus nebula. Indeed, the shielding provided by this dust could help
explain how molecules survive in the presence of the intense UV radiation field
produced by $\eta$ Carinae. The dust located in the central few arcseconds
around $\eta$ Carinae and the molecular component described here have most
likely formed in situ, out of material expelled by the massive interacting
binary system. Thus, $\eta$ Carinae offers us a rare glimpse on the processes
leading to the formation of dust and molecules around massive stars that are so
relevant to the interpretation of dust and molecule detections at high
redshifts.


title: An observation of circular RNAs in bacterial RNA-seq data

abstract:
  Circular RNAs (circRNAs) are a class of RNA with an important role in micro
RNA (miRNA) regulation recently discovered in Human and various other
eukaryotes as well as in archaea. Here, we have analyzed RNA-seq data obtained
from {\it Enterococcus faecalis} and {\it Escherichia coli} in a way similar to
previous studies performed on eukaryotes. We report observations of circRNAs in
RNA-seq data that are reproducible across multiple experiments performed with
different protocols or growth conditions.


title: Dynamics of meandering spiral waves with weak lattice perturbations

abstract:
  Re-entrant spiral waves are observed in many different situations in nature,
perhaps most importantly in excitable electrophysiological tissue where they
are believed to be responsible for pathological conditions such as cardiac
arrhythmias, epileptic seizures and hallucinations. Mathematically, spiral
waves occur as solutions to systems of reaction-diffusion partial differential
equations (RDPDEs) which are frequently used as models for electrophysiological
phenomena. Because of the invariance of these RDPDEs with respect to the
Euclidean group SE(2) of planar translations and rotations, much progress has
been made in understanding the dynamics and bifurcations of spiral waves using
the theory of group-equivariant dynamical systems. In reality however,
Euclidean symmetry is at best an approximation. Inhomogeneities and anisotropy
in the medium of propagation of the waves break the Euclidean symmetry, and can
lead to such phenomena as anchoring and drifting. In this paper, we study the
effects on quasi-periodic meandering spiral waves of a small perturbation which
breaks the continuous SE(2) symmetry, but preserves the symmetry of a regular
square lattice.


title: Sustaining educational and public outreach programs in astronomy

abstract:
  We advocate meaningful support of sustained education-outreach partnerships
between regional metropolitan undergraduate institutions and astronomical clubs
and societies. We present our experience as an example, in which we have grown
a partnership between the University of Michigan-Dearborn (hereafter UM-D, a
4-year primarily undergraduate institution or PUI), Henry Ford College
(hereafter HFC, a 2-year undergraduate college), and maintained a strong
collaboration with the Ford Amateur Astronomy Club (FAAC), which is highly
active in the Detroit Metropolitan Area. By allowing each organization to play
to its strengths, we have developed a continuum of education-outreach efforts
at all levels, with connecting tissue between the previously disparate efforts.
To-date, faculty and staff effort on these initiatives has been nearly entirely
voluntary and somewhat ad-hoc. Here we suggest an initiative to sustain the
continuum of education-outreach for the long-term. There are two levels to the
suggested initiative. Firstly, partner institutions should dedicate at least
half an FTE of faculty or staff effort specifically to education and outreach
development. Secondly, professional societies like the AAS now have a great
opportunity to support the education-outreach continuum at a national level, by
facilitating communication between institutions and clubs that are considering
a long-term partnership, by acting as a central resource for such partnerships,
and possibly by convening or sponsoring events such as professional meetings
among the metropolitan educational community.


title:
Effect of atomic disorder and Ce doping on superconductivity of
  Ca3Rh4Sn13: Electric transport properties under high pressure

abstract:
  We report the observation of a superconducting state below 8K coexistent with
a spin-glass state caused by atomic disorder in Ce substituted Ca3Rh4Sn13.
Measurements of specific heat, resistivity, and magnetism reveal the existence
of inhomogeneous superconductivity in samples doped with Ce with
superconducting critical temperatures Tc higher than those observed in the
parent compound. For Ca3Rh4Sn13, the negative value of the change in
resistivity with pressure P, correlates well with the calculated decrease in
the density of states at the Fermi energy with P. Based on band structure
calculations performed under pressure, we demonstrate how the change in DOS
would affect Tc of Ca3Rh4Sn13 under negative lattice pressure in samples that
are strongly defected by quenching.


title:
Thermodynamics vs. local density fluctuations in the
  metal/Mott-insulator crossover

abstract:
  The crossover between a metal and a Mott insulator leads to a localization of
fermions from delocalized Bloch states to localized states. We experimentally
study this crossover using fermionic atoms in an optical lattice by measuring
thermodynamic and local (on--site) density correlations. In the metallic phase
at incommensurable filling we observe the violation of the local
fluctuation--dissipation theorem indicating that the thermodynamics cannot be
explained by local observables. In contrast, in the Mott-insulator we observe
the convergence of local and thermodynamic fluctuations indicating the absence
of long--range density-density correlations.


title: Experimental bounds on collapse models from gravitational wave detectors

abstract:
  Wave function collapse models postulate a fundamental breakdown of the
quantum superposition principle at the macroscale. Therefore, experimental
tests of collapse models are also fundamental tests of quantum mechanics. Here,
we compute the upper bounds on the collapse parameters, which can be inferred
by the gravitational wave detectors LIGO, LISA Pathfinder, and AURIGA. We
consider the most widely used collapse model, the continuous spontaneous
localization (CSL) model. We show that these experiments exclude a huge portion
of the CSL parameter space, the strongest bound being set by the recently
launched space mission LISA Pathfinder. We also rule out a proposal for
quantum-gravity-induced decoherence.


title: Query-Reduction Networks for Question Answering

abstract:
  In this paper, we study the problem of question answering when reasoning over
multiple facts is required. We propose Query-Reduction Network (QRN), a variant
of Recurrent Neural Network (RNN) that effectively handles both short-term
(local) and long-term (global) sequential dependencies to reason over multiple
facts. QRN considers the context sentences as a sequence of state-changing
triggers, and reduces the original query to a more informed query as it
observes each trigger (context sentence) through time. Our experiments show
that QRN produces the state-of-the-art results in bAbI QA and dialog tasks, and
in a real goal-oriented dialog dataset. In addition, QRN formulation allows
parallelization on RNN's time axis, saving an order of magnitude in time
complexity for training and inference.


title:
Nonlinear stability results for the modified Mullins-Sekerka and the
  surface diffusion flow

abstract:
  It is shown that any three-dimensional periodic configuration that is
strictly stable for the area functional is exponentially stable for the surface
diffusion flow and for the Mullins-Sekerka or Hele-Shaw flow. The same result
holds for three-dimensional periodic configurations that are strictly stable
with respect to the sharp-interface Ohta-Kawaski energy. In this case, they are
exponentially stable for the so-called modified Mullins-Sekerka flow.


title:
Quantum Superlattices, Wannier Stark Ladders and the 'Resonance'
  technique

abstract:
  We present a new method for solving the Schrodinger equation using the
Lossless Transmission Line Model (LTL). The LTL model although extensively used
in fiber optics and optical fiber design, it has not yet found application in
solid state problems. We develop the transformation theory mapping the wave
equation to LTL and we apply the model to the case of a solid state periodic
lattice. We extend the theory with an additional Wannier-Stark term and we show
with results the flexibility and the strength of the technique. The advantages
of the method for arbitrary potentials are also stressed.


title: Latest MAGIC discoveries pushing redshift boundaries in VHE Astrophysics

abstract:
  The search for detection of gamma-rays from distant AGNs by Imaging
Atmospheric Cherenkov Telescopes (IACTs) is challenging at high redshifts, not
only because of lower flux due to the distance of the source, but also due to
the consequent absorption of gamma-rays by the extragalactic background light
(EBL). Before the MAGIC discoveries reported in this work, the farthest source
ever detected in the VHE domain was the blazar PKS 1424+240, at z>0.6. MAGIC, a
system of two 17 m of diameter IACTs located in the Canary island of La Palma,
has been able to go beyond that limit and push the boundaries for VHE detection
to redshifts z~ 1. The two sources detected and analyzed, the blazar QSO
B0218+357 and the FSRQ PKS 1441+25 are located at redshift z=0.944 and z=0.939
respectively. QSO B0218+357 is also the first gravitational lensed blazar ever
detected in VHE. The activity, triggered by Fermi-LAT in high energy
gamma-rays, was followed up by other instruments, such as the KVA telescope in
the optical band and the Swift-XRT in X-rays. In the present work we show
results on MAGIC analysis on QSO B0218+357 and PKS 1441+25 together with
multiwavelength lightcurves. The collected dataset allowed us to test for the
first time the present generation of EBL models at such distances.


title:
Regularization With Stochastic Transformations and Perturbations for
  Deep Semi-Supervised Learning

abstract:
  Effective convolutional neural networks are trained on large sets of labeled
data. However, creating large labeled datasets is a very costly and
time-consuming task. Semi-supervised learning uses unlabeled data to train a
model with higher accuracy when there is a limited set of labeled data
available. In this paper, we consider the problem of semi-supervised learning
with convolutional neural networks. Techniques such as randomized data
augmentation, dropout and random max-pooling provide better generalization and
stability for classifiers that are trained using gradient descent. Multiple
passes of an individual sample through the network might lead to different
predictions due to the non-deterministic behavior of these techniques. We
propose an unsupervised loss function that takes advantage of the stochastic
nature of these methods and minimizes the difference between the predictions of
multiple passes of a training sample through the network. We evaluate the
proposed method on several benchmark datasets.


title: Self-duality and shock dynamics in the $n$-component priority ASEP

abstract:
  We study the $n$-component priority asymmetric simple exclusion process
($n$-ASEP) with reflecting boundaries. We obtain all invariant measures in
explicit form and prove reversibility. Using the symmetry of the generator of
the process under the quantum algebra $U_q[\mathfrak{gl}(n+1)]$ we construct
duality functions with respect to which the $n$-ASEP is self-dual, both for the
finite and the infinite integer lattice. For the $n$-ASEP on the infinite
lattice we use self-duality to derive in explicit form the time evolution of a
family of measures with $K$ shocks in terms of the transition probability of
$K$ coloured particles in a shock exclusion process with particle-dependent
hopping rates and nearest-neighbour colour exchange. This process is a gas of
particles that forms a bound state, corresponding to shock coalescence on
macroscopic scale.


title:
Bernstein modal basis: application to the spectral Petrov-Galerkin
  method for fractional partial differential equations

abstract:
  In the spectral Petrov-Galerkin methods, the trial and test functions are
required to satisfy particular boundary conditions. By a suitable linear
combination of orthogonal polynomials, a basis, that is called the modal basis,
is obtained. In this paper, we extend this idea to the non-orthogonal dual
Bernstein polynomials. A compact general formula is derived for the modal basis
functions based on dual Bernstein polynomials. Then, we present a
Bernstein-spectral Petrov-Galerkin method for a class of time fractional
partial differential equations with Caputo derivative. It is shown that the
method leads to banded sparse linear systems for problems with constant
coefficient. Some numerical examples are provided to show the efficiency and
the spectral accuracy of the method.


title: Impossibility in Belief Merging

abstract:
  With the aim of studying social properties of belief merging and having a
better understanding of impossibility, we extend in three ways the framework of
logic-based merging introduced by Konieczny and Pino P\'erez. First, at the
level of representation of the information, we pass from belief bases to
complex epistemic states. Second, the profiles are represented as functions of
finite societies to the set of epistemic states (a sort of vectors) and not as
multisets of epistemic states. Third, we extend the set of rational postulates
in order to consider the epistemic versions of the classical postulates of
Social Choice Theory: Standard Domain, Pareto Property, Independence of
Irrelevant Alternatives and Absence of Dictator. These epistemic versions of
social postulates are given, essentially, in terms of the finite propositional
logic. We state some representation theorems for these operators. These
extensions and representation theorems allow us to establish an epistemic and
very general version of Arrow's Impossibility Theorem. One of the interesting
features of our result, is that it holds for different representations of
epistemic states; for instance conditionals, Ordinal Conditional functions and,
of course, total preorders.


title:
In the Shadows, Shape Priors Shine: Using Occlusion to Improve
  Multi-Region Segmentation

abstract:
  We present a new algorithm for multi-region segmentation of 2D images with
objects that may partially occlude each other. Our algorithm is based on the
observation hat human performance on this task is based both on prior knowledge
about plausible shapes and taking into account the presence of occluding
objects whose shape is already known - once an occluded region is identified,
the shape prior can be used to guess the shape of the missing part. We capture
the former aspect using a deep learning model of shape; for the latter, we
simultaneously minimize the energy of all regions and consider only unoccluded
pixels for data agreement.
  Existing algorithms incorporating object shape priors consider every object
separately in turn and can't distinguish genuine deviation from the expected
shape from parts missing due to occlusion. We show that our method
significantly improves on the performance of a representative algorithm, as
evaluated on both preprocessed natural and synthetic images. Furthermore, on
the synthetic images, we recover the ground truth segmentation with good
accuracy.


title: Normal-metal quasiparticle traps for superconducting qubits

abstract:
  The presence of quasiparticles in superconducting qubits emerges as an
intrinsic constraint on their coherence. While it is difficult to prevent the
generation of quasiparticles, keeping them away from active elements of the
qubit provides a viable way of improving the device performance. Here we
develop theoretically and validate experimentally a model for the effect of a
single small trap on the dynamics of the excess quasiparticles injected in a
transmon-type qubit. The model allows one to evaluate the time it takes to
evacuate the injected quasiparticles from the transmon as a function of trap
parameters. With the increase of the trap size, this time decreases
monotonically, saturating at the level determined by the quasiparticles
diffusion constant and the qubit geometry. We determine the characteristic trap
size needed for the relaxation time to approach that saturation value.


title:
Algebraic Problems Equivalent to Beating Exponent 3/2 for Polynomial
  Factorization over Finite Fields

abstract:
  The fastest known algorithm for factoring univariate polynomials over finite
fields is the Kedlaya-Umans (fast modular composition) implementation of the
Kaltofen-Shoup algorithm. It is randomized and takes $\widetilde{O}(n^{3/2}\log
q + n \log^2 q)$ time to factor polynomials of degree $n$ over the finite field
$\mathbb{F}_q$ with $q$ elements. A significant open problem is if the $3/2$
exponent can be improved. We study a collection of algebraic problems and
establish a web of reductions between them. A consequence is that an algorithm
for any one of these problems with exponent better than $3/2$ would yield an
algorithm for polynomial factorization with exponent better than $3/2$.


title: Strongvelope Multi-Party Encrypted Messaging Protocol design document

abstract:
  In this document we describe the design of a multi-party messaging encryption
protocol "Strongvelope". We hope that it will prove useful to people interested
in understanding the inner workings of this protocol as well as cryptography
and security experts to review the underlying concepts and assumptions.
  In this design paper we are outlining the perspective of chat message
protection through the Strongvelope module. This is different from the product
(the Mega chat) and the transport means which it will be used with. Aspects of
the chat product and transport are only referred to where appropriate, but are
not subject to discussion in this document.


title: Quantum effects in the interference of photon number states

abstract:
  Multi-photon interference results in modulations of output probabilities with
phase shift periods that are much shorter than 2 Pi. Here, we investigate the
physics behind these statistical patterns in the case of well-defined photon
numbers in the input and output modes of a two-path interferometer. We show
that the periodicity of the multi-photon interference is related to the weak
value of the unobserved intensity difference between the two arms of the
interferometer. This means that the operator relations between the photon
number differences in input, path, and output can be used to determine the
periodicity of the experimentally observed quantum interference, establishing
an important link between the classical causality of random phase interference
and quantum effects that depend on the superposition of classically distinct
possibilities.


title: Driving Skyrmions in a Composite Bilayer

abstract:
  Magnetic Skyrmions and multiferroics are the most interesting objects in
nanostructure science that have great potential in future spin-electronic
technology. The study of multiferroic Skyrmions has attracted much interest in
recent years. This article reports magnetic Bloch Skyrmions induced by an
electric driving field in a composite bilayer (chiral-magnetic/ferroelectric
bilayer) lattice. By using the spin dynamics method, we use a classical
magnetic spin model and an electric pseudospin model, which are coupled by a
strong magnetoelectric coupling in the dynamical simulations. Interestingly, we
observe some skyrmion-like objects in the electric component either during the
switching process or by applying a magnetic field, which is due to the
connection between the electric and the magnetic structures.


title: Semi-Supervised Learning for Neural Machine Translation

abstract:
  While end-to-end neural machine translation (NMT) has made remarkable
progress recently, NMT systems only rely on parallel corpora for parameter
estimation. Since parallel corpora are usually limited in quantity, quality,
and coverage, especially for low-resource languages, it is appealing to exploit
monolingual corpora to improve NMT. We propose a semi-supervised approach for
training NMT models on the concatenation of labeled (parallel corpora) and
unlabeled (monolingual corpora) data. The central idea is to reconstruct the
monolingual corpora using an autoencoder, in which the source-to-target and
target-to-source translation models serve as the encoder and decoder,
respectively. Our approach can not only exploit the monolingual corpora of the
target language, but also of the source language. Experiments on the
Chinese-English dataset show that our approach achieves significant
improvements over state-of-the-art SMT and NMT systems.


title:
Agreement-based Learning of Parallel Lexicons and Phrases from
  Non-Parallel Corpora

abstract:
  We introduce an agreement-based approach to learning parallel lexicons and
phrases from non-parallel corpora. The basic idea is to encourage two
asymmetric latent-variable translation models (i.e., source-to-target and
target-to-source) to agree on identifying latent phrase and word alignments.
The agreement is defined at both word and phrase levels. We develop a Viterbi
EM algorithm for jointly training the two unidirectional models efficiently.
Experiments on the Chinese-English dataset show that agreement-based learning
significantly improves both alignment and translation performance.


title: mpENC Multi-Party Encrypted Messaging Protocol design document

abstract:
  This document is a technical overview and discussion of our work, a protocol
for secure group messaging. By secure we mean for the actual users i.e.
end-to-end security, as opposed to "secure" for irrelevant third parties.
  Our work provides everything needed to run a messaging session between real
users on top of a real transport protocol. That is, we specify not just a key
exchange, but when and how to run these relative to transport-layer events; how
to achieve liveness properties such as reliability and consistency, that are
time-sensitive and lie outside of the send-receive logic that cryptography-only
protocols often restrict themselves to; and offer suggestions for displaying
accurate (i.e. secure) but not overwhelming information in user interfaces.
  We aim towards a general-purpose unified protocol. In other words, we'd
prefer to avoid creating a completely new protocol merely to support
automation, or asynchronity, or a different transport protocol. This would add
complexity to the overall ecosystem of communications protocols. It is simply
unnecessary if the original protocol is designed well, as we have tried to do.
  That aim is not complete -- our full protocol system, as currently
implemented, is suitable only for use with certain instant messaging protocols.
However, we have tried to separate out conceptually-independent concerns, and
solve these individually using minimal assumptions even if other components
make extra assumptions. This means that many components of our full system can
be reused in future protocol extensions, and we know exactly which components
must be replaced in order to lift the existing constraints on our full system.


title: Mega Key Authentication Mechanism

abstract:
  For secure communication it is not just sufficient to use strong cryptography
with good and strong keys, but to actually have the assurance, that the keys in
use for it are authentic and from the contact one is expecting to communicate
with. Without that, it is possible to be subject to impersonation or
man-in-the-middle (MitM) attacks.
  Mega meets this problem by providing a hierarchical authentication mechanism
for contacts and their keys. To avoid any hassle when using multiple types of
keys and key pairs for different purposes, the whole authentication mechanism
is brought down to a single "identity key".


title:
Periodic solutions in an SIRWS model with immune boosting and
  cross-immunity

abstract:
  Incidence of whooping cough, an infection caused by Bordetella pertussis and
Bordetella parapertussis, has been on the rise since the 1980s in many
countries. Immunological interactions, such as immune boosting and
cross-immunity between pathogens, have been hypothesised to be important
drivers of epidemiological dynamics. We present a two-pathogen model of
transmission which examines how immune boosting and cross-immunity can
influence the timing and severity of epidemics. We use a combination of
numerical simulations and bifurcation techniques to study the dynamical
properties of the system, particularly the conditions under which stable
periodic solutions are present. We derive analytic expressions for the steady
state of the single-pathogen model, and give a condition for the presence of
periodic solutions. A key result from our two-pathogen model is that, while
studies have shown that immune boosting at relatively strong levels can
independently generate periodic solutions, cross-immunity allows for the
presence of periodic solutions even when the level of immune boosting is weak.
Asymmetric cross-immunity can produce striking increases in the incidence and
period. Our study underscores the importance of developing a better
understanding of the immunological interactions between pathogens in order to
improve model-based interpretations of epidemiological data.


title: Cyclic codes over $\mathbb{Z}_4[u]/\langle u^k\rangle$ of odd length

abstract:
  Let $R=\mathbb{Z}_{4}[u]/\langle
u^k\rangle=\mathbb{Z}_{4}+u\mathbb{Z}_{4}+\ldots+u^{k-1}\mathbb{Z}_{4}$
($u^k=0$) where $k\in \mathbb{Z}^{+}$ satisfies $k\geq 2$. For any odd positive
integer $n$, it is known that cyclic codes over $R$ of length $n$ are
identified with ideals of the ring $R[x]/\langle x^{n}-1\rangle$. In this
paper, an explicit representation for each cyclic code over $R$ of length $n$
is provided and a formula to count the number of codewords in each code is
given. Then a formula to calculate the number of cyclic codes over $R$ of
length $n$ is obtained. Precisely, the dual code of each cyclic code and
self-dual cyclic codes over $R$ of length $n$ are investigated. When $k=4$,
some optimal quasi-cyclic codes over $\mathbb{Z}_{4}$ of length $28$ and index
$4$ are obtained from cyclic codes over $R=\mathbb{Z}_{4} [u]/\langle
u^4\rangle$.


title: Using Hilbert transform and classical chains to simulate quantum walks

abstract:
  We propose a simulation strategy which uses a classical device of linearly
coupled chain of springs to simulate quantum dynamics, in particular the
quantum walks. Through this strategy, we obtain the quantum wave function from
classical evolution. Specially, this goal is achieved with the classical
momenta of the particles on the chain and their Hilbert transform, from which
we construct the many-body momentum and Hilbert transformed momentum pair
correlation functions yielding the real and imaginary parts of the wave
function, respectively. With such wave function, we show that the classical
chain's energy and heat spreading densities can be related to the wave
function's modulus square. This relation indicates a concept of "phonon random
walks", and thus it provides a new perspective to understand ballistic heat
transport. The results here may give a definite answer to Feynman's idea of
using a classical device to simulate quantum physics.


title: High spatial resolution FeXII observations of solar active region

abstract:
  We use UV spectral observations of active regions with the Interface Region
Imaging Spectrograph (IRIS) to investigate the properties of the coronal FeXII
1349.4A emission at unprecedented high spatial resolution (~0.33"). We find
that by using appropriate observational strategies (i.e., long exposures,
lossless compression), FeXII emission can be studied with IRIS at high spatial
and spectral resolution, at least for high density plasma (e.g., post-flare
loops, and active region moss). We find that upper transition region (moss)
FeXII emission shows very small average Doppler redshifts (v_Dop ~3 km/s), as
well as modest non-thermal velocities (with an average ~24 km/s, and the peak
of the distribution at ~15 km/s). The observed distribution of Doppler shifts
appears to be compatible with advanced 3D radiative MHD simulations in which
impulsive heating is concentrated at the transition region footpoints of a hot
corona. While the non-thermal broadening of FeXII 1349.4A peaks at similar
values as lower resolution simultaneous Hinode/EIS measurements of FeXII 195A,
IRIS observations show a previously undetected tail of increased non-thermal
broadening that might be suggestive of the presence of subarcsecond heating
events. We find that IRIS and EIS non-thermal line broadening measurements are
affected by instrumental effects that can only be removed through careful
analysis. Our results also reveal an unexplained discrepancy between observed
195.1/1349.4A FeXII intensity ratios and those predicted by the CHIANTI atomic
database.


title: Do triaxial supramassive compact stars exist?

abstract:
  We study quasiequilibrium solutions of triaxially deformed rotating compact
stars -- a generalization of Jacobi ellipsoids under relativistic gravity and
compressible equations of state (EOS). For relatively stiff (piecewise)
polytropic EOSs, we find supramassive triaxial solutions whose masses exceed
the maximum mass of the spherical solution, but are always lower than those of
axisymmetric equilibriums. The difference in the maximum masses of triaxial and
axisymmetric solutions depends sensitively on the EOS. If the difference turns
out to be only about 10%, it will be strong evidence that the EOS of high
density matter becomes substantially softer in the core of neutron stars. This
finding opens a novel way to probe phase transitions of high density nuclear
matter using detections of gravitational waves from new born neutron stars or
magnetars under fallback accretion.


title:
Spin-orbit coupling and strong electronic correlations in cyclic
  molecules

abstract:
  In atoms spin-orbit coupling (SOC) cannot raise the angular momentum above a
maximum value or lower it below a minimum. Here we show that this need not be
the case in materials built from nanoscale structures including multi-nuclear
coordination complexes, materials with decorated lattices, or atoms on
surfaces. In such cyclic molecules the electronic spin couples to currents
running around the molecule. For odd-fold symmetric molecules (e.g., odd
membered rings) the SOC is highly analogous to the atomic case; but for
even-fold symmetric molecules every angular momentum state can be both raised
and lowered. These differences arise because for odd-fold symmetric molecules
the maximum and minimum molecular orbital angular momentum states are time
reversal conjugates, whereas for even-fold symmetric molecules they are aliases
of the same single state. We show, from first principles calculations, that in
suitable molecules this molecular SOC is large, compared to the energy
differences between frontier molecular orbitals. Finally, we show that, when
electronic correlations are strong, molecular SOC can cause highly anisotropic
exchange interactions and discuss how this can lead to effective spin models
with compass Hamiltonians.


title: Evidence for periodicity in 43 year-long monitoring of NGC 5548

abstract:
  We present an analysis of 43 years (1972 to 2015) of spectroscopic
observations of the Seyfert 1 galaxy NGC 5548. This includes 12 years of new
unpublished observations (2003 to 2015). We compiled about 1600 H$\beta$
spectra and analyzed the long-term spectral variations of the 5100 \AA\
continuum and the H$\beta$ line. Our analysis is based on standard procedures
including the Lomb-Scargle method, which is known to be rather limited to such
heterogeneous data sets, and new method developed specifically for this project
that is more robust and reveals a $\sim$5700 day periodicity in the continuum
light curve, the H$\beta$ light curve and the radial velocity curve of the red
wing of the H$\beta$ line. The data are consistent with orbital motion inside
the broad emission line region of the source. We discuss several possible
mechanisms that can explain this periodicity, including orbiting dusty and
dust-free clouds, a binary black hole system, tidal disruption events, and the
effect of an orbiting star periodically passing through an accretion disc.

categories: astro-ph.HE astro-ph.GA astro-ph.IM physics.data-an


title: A criterion for Leavitt path algebras having invariant basis number

abstract:
  In this paper, we give a matrix-theoretic criterion for the Leavitt path
algebra of a finite graph has Invariant Basis Number. Consequently, we show
that the Cohn path algebra of a finite graph has Invariant Basis Number, as
well as provide some certain classes of finite graphs for which Leavitt path
algebras having Invariant Basis Number.


title: A Degree Condition for a Graph to have $(a,b)$-Parity Factors

abstract:
  Let $a,b,n$ be three positive integers such that $a\equiv b\pmod 2$ and
$n\geq b(a+b)(a+b+2)/(2a)$. Let $G$ be a graph of order $n$ with minimum degree
at least $a+b/a-1$. We show that $G$ has an $(a,b)$-parity factor, if
$max\{d_G(u),d_G(v)\}\geq \frac{an}{a+b}$ for any two nonadjacent vertices
$u,v$ of $G$. It is an extension of Nishimura's results for the existence of
$k$-factors (\emph{J. Graph Theory}, \textbf{16} (1992), 141--151) and
generalizes Li and Cai's result in some senses (\emph{J. Graph Theory},
\textbf{27} (1998), 1--6). These conditions are tight.


title:
High Throughput Neural Network based Embedded Streaming Multicore
  Processors

abstract:
  With power consumption becoming a critical processor design issue,
specialized architectures for low power processing are becoming popular.
Several studies have shown that neural networks can be used for signal
processing and pattern recognition applications. This study examines the design
of memristor based multicore neural processors that would be used primarily to
process data directly from sensors. Additionally, we have examined the design
of SRAM based neural processors for the same task. Full system evaluation of
the multicore processors based on these specialized cores were performed taking
I/O and routing circuits into consideration. The area and power benefits were
compared with traditional multicore RISC processors. Our results show that the
memristor based architectures can provide an energy efficiency between three
and five orders of magnitude greater than that of RISC processors for the
benchmarks examined.


title:
Complete Bernstein functions and subordinators with nested ranges. A
  note on a paper by P. Marchal

abstract:
  Let $\alpha:[0,1]\to [0,1]$ be a measurable function. It was proved by P.
Marchal \cite{Mar15} that the function
  $$
  \phi^{(\alpha)}(\lambda):=\exp\left[
  \int_0^1\frac{\lambda-1}{1+(\lambda-1)x}\,\alpha(x)\,d x
  \right],\quad \lambda>0
  $$ is a special Bernstein function. Marchal used this to construct, on a
single probability space, a family of regenerative sets $\mathcal R^{(\alpha)}$
such that $\mathcal{R}^{(\alpha)} \stackrel{\text{law}}{=}
\overline{\{S^{(\alpha)}_t:t\geq 0\}}$ ($S^{(\alpha)}$ is the subordinator with
Laplace exponent $\phi^{(\alpha)}$) and $\mathcal R^{(\alpha)}\subset \mathcal
R^{(\beta)}$ whenever $\alpha\leq\beta$.
  We give two simple proofs showing that $\phi^{(\alpha)}$ is a complete
Bernstein function and extend Marchal's construction to all complete Bernstein
functions.


title: A note on Plans's paper of Noether's problem

abstract:
  Let $p$ be a prime number and $\zeta_p$ be a primitive $p$-th root of unity
in $\bm{C}$. Let $k$ be a field and $k(x_0,\ldots,x_{p-1})$ be the rational
function field of $p$ variables over $k$. Suppose that $G=\langle\sigma\rangle
\simeq C_p$ acts on $k(x_0,\ldots,x_{p-1})$ by $k$-automorphisms defined as
$\sigma:x_0\mapsto x_1\mapsto\cdots\mapsto x_{p-1}\mapsto x_0$. Denote by $P$
the set of all prime numbers and define $P_0=\{p\in P:\bm{Q}(\zeta_p)$ is of
class number one$\}$. Theorem. If $k$ is an algebraic number field and $p\in
P\backslash (P_0\cup P_k)$, then $k(x_0,\ldots,x_{p-1})^G$ is not stably
rational over $k$ where $P_k=\{p\in P: p$ is ramified in $k\}$.


title: The combined effect of precession and convection on the dynamo action

abstract:
  To understand the generation of the Earth's and planetary magnetic fields, we
investigate numerically the combined effect of precession and convection on the
dynamo action in a spherical shell. The convection alone, the precession alone
and the combined effect of convection and precession are studied at the low
Ekman number at which the precessing flow is already unstable. The key result
is that although the precession or convection alone is not strong to support
the dynamo action the combined effect of precession and convection can support
the dynamo action because of the resonance of precessional and convective
instabilities. This result may interpret why the geodynamo maintains for such a
long history compared to the Martian dynamo.

categories: astro-ph.EP astro-ph.SR physics.flu-dyn physics.geo-ph


title: A Nekrasov-Okounkov formula for Macdonald polynomials

abstract:
  We prove a Macdonald polynomial analogue of the celebrated Nekrasov-Okounkov
hook-length formula from the theory of random partitions. As an application we
obtain a proof of one of the main conjectures of Hausel and Rodriguez-Villegas
from their work on mixed Hodge polynomials of the moduli space of stable Higgs
bundles on Riemann surfaces.


title: Algebraic Equations in State Condition

abstract:
  In this paper, we will prove that a problem deciding whether there is an
upper-triangular coordinate in which a character is not in the state of a
Hilbert point is NP-hard. This problem is related to the GIT-semistability of a
Hilbert point.


title: Deep Reinforcement Learning With Macro-Actions

abstract:
  Deep reinforcement learning has been shown to be a powerful framework for
learning policies from complex high-dimensional sensory inputs to actions in
complex tasks, such as the Atari domain. In this paper, we explore output
representation modeling in the form of temporal abstraction to improve
convergence and reliability of deep reinforcement learning approaches. We
concentrate on macro-actions, and evaluate these on different Atari 2600 games,
where we show that they yield significant improvements in learning speed.
Additionally, we show that they can even achieve better scores than DQN. We
offer analysis and explanation for both convergence and final results,
revealing a problem deep RL approaches have with sparse reward signals.


title:
Natural Scene Character Recognition Using Robust PCA and Sparse
  Representation

abstract:
  Natural scene character recognition is challenging due to the cluttered
background, which is hard to separate from text. In this paper, we propose a
novel method for robust scene character recognition. Specifically, we first use
robust principal component analysis (PCA) to denoise character image by
recovering the missing low-rank component and filtering out the sparse noise
term, and then use a simple Histogram of oriented Gradient (HOG) to perform
image feature extraction, and finally, use a sparse representation based
classifier for recognition. In experiments on four public datasets, namely the
Char74K dataset, ICADAR 2003 robust reading dataset, Street View Text (SVT)
dataset and IIIT5K-word dataset, our method was demonstrated to be competitive
with the state-of-the-art methods.


title: New results for reaction rate of the proton radiative capture on 3H

abstract:
  Calculations of the reaction rate of the proton radiative capture on 3H at
temperatures from 0.01 T9 up to 5 T9, which are based on the theoretical
results for the astrophysical S-factor and take into account the latest
experimental data, were carried out. Theoretical results for the S-factor at
energies from 1 keV up to 5 MeV were obtained in the framework of the modified
potential cluster model with the classification of orbital states according to
Young tableaux. On the basis of used nuclear model of the interaction of p and
3H particles there was shown possibility of description the latest experimental
data for the S-factor at the energy range from 50 keV up to 5 MeV.


title: Masking Strategies for Image Manifolds

abstract:
  We consider the problem of selecting an optimal mask for an image manifold,
i.e., choosing a subset of the pixels of the image that preserves the
manifold's geometric structure present in the original data. Such masking
implements a form of compressive sensing through emerging imaging sensor
platforms for which the power expense grows with the number of pixels acquired.
Our goal is for the manifold learned from masked images to resemble its full
image counterpart as closely as possible. More precisely, we show that one can
indeed accurately learn an image manifold without having to consider a large
majority of the image pixels. In doing so, we consider two masking methods that
preserve the local and global geometric structure of the manifold,
respectively. In each case, the process of finding the optimal masking pattern
can be cast as a binary integer program, which is computationally expensive but
can be approximated by a fast greedy algorithm. Numerical experiments show that
the relevant manifold structure is preserved through the data-dependent masking
process, even for modest mask sizes.


title:
Effects of energetic particles on zonal flow generation by toroidal
  Alfven eigenmode

abstract:
  Generation of zonal ow (ZF) by energetic particle (EP) driven toroidal Alfven
eigenmode (TAE) is investigated using nonlinear gyrokinetic theory. It is found
that, nonlinear resonant EP contri- bution dominates over the usual Reynolds
and Maxwell stresses due to thermal plasma nonlinear response. ZF can be forced
driven in the linear growth stage of TAE, with the growth rate being twice the
TAE growth rate. The ZF generation mechanism is shown to be related to
polarization induced by resonant EP nonlinearity. The generated ZF has both the
usual meso-scale and micro- scale radial structures. Possible consequences of
this forced driven ZF on the nonlinear dynamics of TAE are also discussed.


title:
Convergence of Phase-Field Free Energy and Boundary Force for Molecular
  Solvation

abstract:
  We study a phase-field variational model for the solvaiton of charged
molecules with an implicit solvent. The solvation free-energy functional of all
phase fields consists of the surface energy, solute excluded volume and
solute-solvent van der Waals dispersion energy, and electrostatic free energy.
The surface energy is defined by the van der Waals--Cahn--Hilliard functional
with squared gradient and a double-well potential. The electrostatic part of
free energy is defined through the electrostatic potential governed by the
Poisson--Boltzmann equation in which the dielectric coefficient is defined
through the underlying phase field. We prove the continuity of the
electrostatics---its potential, free energy, and dielectric boundary
force---with respect to the perturbation of dielectric boundary. We also prove
the $\Gamma$-convergence of the phase-field free-energy functionals to their
sharp-interface limit, and the equivalence of the convergence of total free
energies to that of all individual parts of free energy. We finally prove the
convergence of phase-field forces to their sharp-interface limit. Such forces
are defined as the negative first variations of the free-energy functional; and
arise from stress tensors. In particular, we obtain the force convergence for
the van der Waals--Cahn--Hilliard functionals with minimal assumptions.


title:
Watch What You Just Said: Image Captioning with Text-Conditional
  Attention

abstract:
  Attention mechanisms have attracted considerable interest in image captioning
due to its powerful performance. However, existing methods use only visual
content as attention and whether textual context can improve attention in image
captioning remains unsolved. To explore this problem, we propose a novel
attention mechanism, called \textit{text-conditional attention}, which allows
the caption generator to focus on certain image features given previously
generated text. To obtain text-related image features for our attention model,
we adopt the guiding Long Short-Term Memory (gLSTM) captioning architecture
with CNN fine-tuning. Our proposed method allows joint learning of the image
embedding, text embedding, text-conditional attention and language model with
one network architecture in an end-to-end manner. We perform extensive
experiments on the MS-COCO dataset. The experimental results show that our
method outperforms state-of-the-art captioning methods on various quantitative
metrics as well as in human evaluation, which supports the use of our
text-conditional attention in image captioning.


title: On the last exit times for spectrally negative L\'evy processes

abstract:
  Using a new approach, for spectrally negative L\'evy processes we find joint
Laplace transforms involving the last exit time (from a semi-infinite
interval), the value of the process at the last exit time and the associated
occupation time, which generalizes some previous results.


title:
$\bar{K}$ -induced formation of the $f_2(1270)$ and $f_2^{'}(1525)$
  resonances on proton targets

abstract:
  We investigate the productiong of $f_2(1270)$ and $f_2^{'}(1525)$ mesons in
the $K^{-}p\to\Lambda{}f_2(1270)$,$K^{-}p\to\Lambda{}f^{'}_2(1525)$ and
$K^{-}p\to{}K^{+}K^{-}\Lambda$ reactions within an effective Lagrangian
approach. For $K^{-}p\to{}f_2\Lambda$ reaction, by considering the
contributions from the $t$-channel $K^{+}$ exchange and $u$-channel nucleon
pole, we get a fairly good description of the experimental measurements about
the total and differential cross sections. Based on the studies of the
$K^{-}p\to{}f_2\Lambda$ reaction, we investigate $K^{-}p\to{}K^{+}K^{-}\Lambda$
reaction including the contributions from the $f_2(1270)$ and $f'_2(1525)$
mesons decaying into $K^+K^-$ pair. The total cross sections and invariant mass
distribution of the $K p \to K^+K^- \Lambda$ reaction are predicted. The
results can be tested in future experiments and therefore offer new clues on
the nature of these tensor states.


title: Finite-time Analysis for the Knowledge-Gradient Policy

abstract:
  We consider sequential decision problems in which we adaptively choose one of
finitely many alternatives and observe a stochastic reward. We offer a new
perspective of interpreting Bayesian ranking and selection problems as adaptive
stochastic multi-set maximization problems and derive the first finite-time
bound of the knowledge-gradient policy for adaptive submodular objective
functions. In addition, we introduce the concept of prior-optimality and
provide another insight into the performance of the knowledge gradient policy
based on the submodular assumption on the value of information. We demonstrate
submodularity for the two-alternative case and provide other conditions for
more general problems, bringing out the issue and importance of submodularity
in learning problems. Empirical experiments are conducted to further illustrate
the finite time behavior of the knowledge gradient policy.


title: Edge-transitive bi-Cayley graphs

abstract:
  A graph $\G$ admitting a group $H$ of automorphisms acting semi-regularly on
the vertices with exactly two orbits is called a {\em bi-Cayley graph\/} over
$H$. Such a graph $\G$ is called {\em normal\/} if $H$ is normal in the full
automorphism group of $\G$, and {\em normal edge-transitive\/} if the
normaliser of $H$ in the full automorphism group of $\G$ is transitive on the
edges of $\G$. % In this paper, we give a characterisation of normal
edge-transitive bi-Cayley graphs, %which form an important subfamily of
bi-Cayley graphs, and in particular, we give a detailed description of
$2$-arc-transitive normal bi-Cayley graphs. Using this, we investigate three
classes of bi-Cayley graphs, namely those over abelian groups, dihedral groups
and metacyclic $p$-groups. We find that under certain conditions, `normal
edge-transitive' is the same as `normal' for graphs in these three classes. As
a by-product, we obtain a complete classification of all connected trivalent
edge-transitive graphs of girth at most $6$, and answer some open questions
from the literature about $2$-arc-transitive, half-arc-transitive and
semisymmetric graphs.


title:
Isoperimetry, scalar curvature, and mass in asymptotically flat
  Riemannian $3$-manifolds

abstract:
  Let $(M, g)$ be an asymptotically flat Riemannian $3$-manifold with
non-negative scalar curvature and positive mass. We show that each leaf of the
canonical foliation through stable constant mean curvature surfaces of the end
of $(M, g)$ is uniquely isoperimetric for the volume it encloses.


title:
Photometric variability of candidate white dwarf binary systems from
  Palomar Transient Factory archival data

abstract:
  We present a sample of 59 periodic variables from the Palomar Transient
Factory, selected from published catalogues of white dwarf (WD) candidates. The
variability can likely be attributed to ellipsoidal variation of the tidally
distorted companion induced by the gravity of the primary (WD or hot subdwarf)
or to the reflection of hot emission by a cooler companion. We searched 11311
spectroscopically or photometrically selected WD candidates from three hot
star/WD catalogues, using the Lomb-Scargle periodogram to single out promising
sources. We present period estimates for the candidates, 45 of which were not
previously identified as periodic variables, and find that most have a period
shorter than a few days. Additionally, we discuss the eclipsing systems in our
sample and present spectroscopic data on selected sources.


title: Uniform perfectness for quasi-metric spaces

abstract:
  The aim of this paper is to investigate the equivalence conditions for
uniform perfectness of quasi-metric spaces. We also obtain the invariant
property of uniform perfectness under quasim\"obius maps in quasi-metric
spaces. In the end, two applications are given.


title: Uniform boundary regularity in almost-periodic homogenization

abstract:
  In the present paper, we generalize the theory of quantitative homogenization
for second-order elliptic systems with rapidly oscillating coefficients in
$APW^2(\mathbb{R}^d)$, which is the space of almost-periodic functions in the
sense of H. Weyl. We obtain the large scale uniform boundary Lipschitz
estimate, for both Dirichlet and Neumann problems in $C^{1,\alpha}$ domains. We
also obtain large scale uniform boundary H\"{o}lder estimates in $C^{1,\alpha}$
domains and $L^2$ Rellich estimates in Lipschitz domains.


title: Phaseless computational imaging with a radiating metasurface

abstract:
  Computational imaging modalities support a simplification of the active
architectures required in an imaging system and these approaches have been
validated across the electromagnetic spectrum. Recent implementations have
utilized pseudo-orthogonal radiation patterns to illuminate an object of
interest---notably, frequency-diverse metasurfaces have been exploited as fast
and low-cost alternative to conventional coherent imaging systems. However,
accurately measuring the complex-valued signals in the frequency domain can be
burdensome, particularly for sub-centimeter wavelengths. Here, computational
imaging is studied under the relaxed constraint of intensity-only measurements.
A novel 3D imaging system is conceived based on 'phaseless' and compressed
measurements, with benefits from recent advances in the field of phase
retrieval. In this paper, the methodology associated with this novel principle
is described, studied, and experimentally demonstrated in the microwave range.
A comparison of the estimated images from both complex valued and phaseless
measurements are presented, verifying the fidelity of phaseless computational
imaging.


title: Bidirectional Long-Short Term Memory for Video Description

abstract:
  Video captioning has been attracting broad research attention in multimedia
community. However, most existing approaches either ignore temporal information
among video frames or just employ local contextual temporal knowledge. In this
work, we propose a novel video captioning framework, termed as
\emph{Bidirectional Long-Short Term Memory} (BiLSTM), which deeply captures
bidirectional global temporal structure in video. Specifically, we first devise
a joint visual modelling approach to encode video data by combining a forward
LSTM pass, a backward LSTM pass, together with visual features from
Convolutional Neural Networks (CNNs). Then, we inject the derived video
representation into the subsequent language model for initialization. The
benefits are in two folds: 1) comprehensively preserving sequential and visual
information; and 2) adaptively learning dense visual features and sparse
semantic representations for videos and sentences, respectively. We verify the
effectiveness of our proposed video captioning framework on a commonly-used
benchmark, i.e., Microsoft Video Description (MSVD) corpus, and the
experimental results demonstrate that the superiority of the proposed approach
as compared to several state-of-the-art methods.


title: Discovery of Tau Neutrino Appearance and Recent Results from OPERA

abstract:
  The OPERA experiment was designed to observe ${\nu_{\mu}}$ ${\rightarrow}$
${\nu_{\tau}}$ oscillations through ${\nu_{\tau}}$ appearance at a baseline of
730 km in the CNGS beam. Newly developed emulsion analysis technology allows to
measure ${\nu_e}$, ${\nu_{\mu}}$ and ${\nu_{\tau}}$ interactions with the
largest emulsion detector ever made. OPERA has detected five ${\nu_{\tau}}$
candidates, allowing to reject the background-only hypothesis at 5.1
${\sigma}$. The parameters for standard and non-standard oscillations are
measured and constrained.


title:
On the BRST and finite field dependent BRST of a model where vector and
  axial vector interaction get mixed up with different weight

abstract:
  The generalized version of a lower dimensional model where vector and axial
vector interaction get mixed up with different weight is considered. The
bosonized version of which does not posses the local gauge symmetry. An attempt
has been made here to construct BRST invariant reformulation of this model
using Batalin Fradlin and Vilkovisky formalism. It is found that the extra
field needed to make it gauge invariant turns into Wess-Zumino scalar with
appropriate choice of gauge fixing. An application of finite field dependent
BRST and anti-BRST transformation is also made here in order to show the
transmutation between the BRST symmetric and the usual non-symmetric version of
the model.


title:
Double shadow of a regular phantom black hole as photons couple to Weyl
  tensor

abstract:
  We have studied the shadow of a regular phantom black hole as photons couple
to Weyl tensor. We find that the coupling yields that photons with different
polarization directions propagate along different paths in the spacetime so
that there exits double shadow for a black hole, which is quite different from
that in the non-coupling case where only a single shadow emerges. The umbra of
black hole increases with the phantom charge and decreases with the coupling
strength. The dependence of the penumbra on the phantom charge and the coupling
strength is converse to that of the umbra. Combining with the supermassive
central object in our Galaxy, we estimated the shadow of the black hole as the
photons couple to Weyl tensor. Our results show that the coupling brings richer
behaviors of the propagation of coupled photon and the shadow of the black hole
in the regular phantom black hole spacetime.


title:
Considerations on the Role of Fall-Back Discs in the Final Stages of the
  Common Envelope Binary Interaction

abstract:
  The common envelope interaction is thought to be the gateway to all evolved
compact binaries and mergers. Hydrodynamic simulations of the common envelope
interaction between giant stars and their companions are restricted to the
dynamical, fast, in-spiral phase. They find that the giant envelope is lifted
during this phase, but remains mostly bound to the system. At the same time,
the orbital separation is greatly reduced, but in most simulations it levels
off? at values larger than measured from observations. We conjectured that
during the post-in-spiral phase the bound envelope gas will return to the
system. Using hydrodynamic simulations, we generate initial conditions for our
simulation that result in a fall-back disk with total mass and angular momentum
in line with quantities from the simulations of Passy et al. We find that the
simulated fall-back event reduces the orbital separation efficiently, but fails
to unbind the gas before the separation levels off once again. We also find
that more massive fall-back disks reduce the orbital separation more
efficiently, but the efficiency of unbinding remains invariably very low. From
these results we deduce that unless a further energy source contributes to
unbinding the envelope (such as was recently tested by Nandez et al.), all
common envelope interactions would result in mergers. On the other hand,
additional energy sources are unlikely to help, on their own, to reduce the
orbital separation. We conclude by discussing our dynamical fall-back event in
the context of a thermally-regulated post-common envelope phase.


title:
Microsimulations of demographic changes in England and Wales under
  different EU referendum scenarios

abstract:
  We perform stochastic microsimulations of the dynamics of England and Wales
population after the British referendum on EU membership, considering different
possible outcomes. Employing available survey data, we model the demographics
of the region over the next generation, as shaped by births, deaths and
international migration. The migration patterns between England and Wales and
the remaining EU countries are modified according to the possible scenarios of
their future relations. We find that Brexit will accelerate the overall
population ageing and the deepening imbalance between workers and retirees but
reduce the population growth and the fraction of women of reproductive age. In
the alternative scenarios of remaining in the EU these effects will be
partially forestalled by the influx of immigrants from current and prospective
EU countries and their children. In all considered scenarios the native British
population declines. Our study demonstrates that microsimulations can be a
useful tool for designing and evaluating the country's policies in the advent
of fundamental transformations.


title:
Ego-Surfing: Person Localization in First-Person Videos Using Ego-Motion
  Signatures

abstract:
  We envision a future time when wearable cameras are worn by the masses and
recording first-person point-of-view videos of everyday life. While these
cameras can enable new assistive technologies and novel research challenges,
they also raise serious privacy concerns. For example, first-person videos
passively recorded by wearable cameras will necessarily include anyone who
comes into the view of a camera -- with or without consent. Motivated by these
benefits and risks, we developed a self-search technique tailored to
first-person videos. The key observation of our work is that the egocentric
head motion of a target person (ie, the self) is observed both in the
point-of-view video of the target and observer. The motion correlation between
the target person's video and the observer's video can then be used to identify
instances of the self uniquely. We incorporate this feature into the proposed
approach that computes the motion correlation over densely-sampled trajectories
to search for a target individual in observer videos. Our approach
significantly improves self-search performance over several well-known face
detectors and recognizers. Furthermore, we show how our approach can enable
several practical applications such as privacy filtering, target video
retrieval, and social group clustering.


title:
Meson/Baryon/Tetraquark Supersymmetry from Superconformal Algebra and
  Light-Front Holography

abstract:
  Superconformal algebra leads to remarkable connections between the masses of
mesons and baryons of the same parity -- supersymmetric relations between the
bosonic and fermionic bound states of QCD. Supercharges connect the mesonic
eigenstates to their baryonic superpartners, where the mesons have internal
angular momentum one unit higher than the baryons. We also predict the
existence of tetraquarks which are degenerate in mass with baryons with the
same angular momentum. An effective supersymmetric light-front Hamiltonian for
hadrons composed of light quarks can be constructed by embedding superconformal
quantum mechanics into AdS space. The breaking of conformal symmetry determines
a unique quark-confining light-front potential for light hadrons including
spin-spin interactions in agreement with the soft-wall AdS/QCD approach and
light-front holography. The mass-squared of the light hadrons can be expressed
as a frame-independent decomposition of contributions from the constituent
kinetic energy, the confinement potential, and spin-spin contributions. The
mass of the pion eigenstate vanishes in the chiral limit. Only one mass
parameter appears; it sets the confinement mass scale, a universal value for
the slope of all Regge trajectories, the nonzero mass of the proton and other
hadrons in the chiral limit, as well as the mass parameter of the pQCD running
coupling. The result is an effective coupling defined at all momenta. The
matching of the high and low momentum-transfer regimes determines a scale $Q_0$
which sets the interface between perturbative and nonperturbative hadron
dynamics. as well as the factorization scale for structure functions and
distribution amplitudes. This procedure, in combination with the
scheme-independent PMC procedure for setting renormalization scales, can
greatly improve the precision of QCD predictions.


title:
Wireless Information and Power Transfer Design for Energy Cooperation
  Distributed Antenna Systems

abstract:
  Distributed antenna systems (DAS) have been widely implemented in
state-of-the-art cellular communication systems to cover dead spots. Recent
studies have also indicated that DAS have advantages in wireless energy
transfer (WET). In this paper, we study simultaneous wireless information and
power transfer (SWIPT) for a multiple-input single-output (MISO) DAS in the
downlink which consists of arbitrarily distributed remote antenna units (RAUs).
In order to save the energy cost, we adopt energy cooperation of energy
harvesting (EH) and two-way energy flows to let the RAUs trade their harvested
energy through the smart grid network. Under individual EH constraints, per-RAU
power constraints and various smart grid considerations, we investigate a power
management strategy that determines how to utilize the stochastically spatially
distributed harvested energy at the RAUs and how to trade the energy with the
smart grid simultaneously to supply maximum wireless information transfer (WIT)
with a minimum WET constraint for a receiver adopting power splitting (PS). Our
analysis shows that the optimal design can be achieved in two steps. The first
step is to maximize a new objective that can simultaneously maximize both WET
and WIT, considering both the smart grid profitable and smart grid neutral
cases. For the grid-profitable case, we derive the optimal full power strategy
and provide a closed-form result to see under what condition this strategy is
used. On the other hand, for the grid-neutral case, we illustrate that the
optimal power policy has a double-threshold structure and present an optimal
allocation strategy. The second step is then to solve the whole problem by
obtaining the splitting power ratio based on the minimum WET constraint.
Simulation results are provided to evaluate the performance under various
settings and characterize the double-threshold structure.


title: Siamese CBOW: Optimizing Word Embeddings for Sentence Representations

abstract:
  We present the Siamese Continuous Bag of Words (Siamese CBOW) model, a neural
network for efficient estimation of high-quality sentence embeddings. Averaging
the embeddings of words in a sentence has proven to be a surprisingly
successful and efficient way of obtaining sentence embeddings. However, word
embeddings trained with the methods currently available are not optimized for
the task of sentence representation, and, thus, likely to be suboptimal.
Siamese CBOW handles this problem by training word embeddings directly for the
purpose of being averaged. The underlying neural network learns word embeddings
by predicting, from a sentence representation, its surrounding sentences. We
show the robustness of the Siamese CBOW model by evaluating it on 20 datasets
stemming from a wide variety of sources.


title:
Spectroscopic Probe of the van der Waals Interaction between Polar
  Molecules and a Curved Surface

abstract:
  We study the shift of rotational levels of a diatomic polar molecule due to
its van der Waals (vdW) interaction with a gently curved dielectric surface at
temperature $T$, and submicron separations. The molecule is assumed to be in
its electronic and vibrational ground state, and the rotational degrees are
described by a rigid rotor model. We show that under these conditions
retardation effects and surface dispersion can be neglected. The level shifts
are found to be independent of $T$, and given by the quantum state averaged
classical electrostatic interaction of the dipole with its image on the
surface. We use a derivative expansion for the static Green's function to
express the shifts in terms of surface curvature. We argue that the curvature
induced line splitting is experimentally observable, and not obscured by
natural line widths and thermal broadening.


title:
Poisson and independent process approximation for random combinatorial
  structures with a given number of components, and near-universal behavior for
  low rank assemblies

abstract:
  We give a general framework for approximations to combinatorial assemblies,
especially suitable to the situation where the number $k$ of components is
specified, in addition to the overall size $n$. This involves a Poisson
process, which, with the appropriate choice of parameter, may be viewed as an
extension of saddlepoint approximation.
  We illustrate the use of this by analyzing the component structure when the
rank and size are specified, and the rank, $r := n-k$, is small relative to
$n$. There is near-universal behavior, in the sense that apart from cases where
the exponential generating function has radius of convergence zero, for
$\ell=1,2,\dots$, when $r \asymp n^\alpha$ for fixed $\alpha \in
(\frac{\ell}{\ell+1}, \frac{\ell+1}{\ell+2})$, the size $L_1$ of the largest
component converges in probabiity to $\ell+2$. Further, when $r \sim t\,
n^{\ell/(\ell+1)}$ for a positive integer $\ell$, and $t \in (0,\infty)$,
$\mathbb{P}\,(L_1 \in \{\ell+1,\ell+2\}) \to 1$, with the choice governed by a
Poisson limit distribution for the number of components of size $\ell+2$. This
was previously observed, for the case $\ell=1$ and the special cases of
permutations and set partitions, using Chen-Stein approximations for the
indicators of attacks and alignments, when rooks are placed randomly on a
triangular board. The case $\ell=1$ is especially delicate, and was not handled
by previous saddlepoint approximations.


title:
Blandford-Znajek mechanism in black holes in alternative theories of
  gravity

abstract:
  According to the Blandford-Znajek mechanism, black hole jets are powered by
the rotational energy of the compact object. In this work, we consider the
possibility that the metric around black holes may not be described by the Kerr
solution and we study how this changes the Blandford-Znajek model. If the
Blandford-Znajek mechanism is responsible for the formation of jets, the
estimate of the jet power in combination with another measurement can test the
nature of black hole candidates and constrain possible deviations from the Kerr
solution. However, this approach might become competitive with respect to other
techniques only when it will be possible to have measurements much more precise
than those available today.


title:
Solitons and hairy black holes in Einstein-non-Abelian-Proca theory in
  anti-de Sitter space-time

abstract:
  We present new soliton and hairy black hole solutions of
Einstein-non-Abelian-Proca theory in asymptotically anti-de Sitter space-time
with gauge group ${\mathfrak {su}}(2)$. For static, spherically symmetric
configurations, we show that the gauge field must be purely magnetic, and solve
the resulting field equations numerically. The equilibrium gauge field is
described by a single function $\omega (r)$, which must have at least one zero.
The solitons and hairy black holes share many properties with the corresponding
solutions in asymptotically flat space-time. In particular, all the solutions
we study are unstable under linear, spherically symmetric, perturbations of the
metric and gauge field.


title: Nuclear medium effects in Drell-Yan process

abstract:
  We study the nuclear medium effects in Drell-Yan process using quark parton
distribution functions calculated in a microscopic nuclear model which takes
into account the effects of Fermi motion, nuclear binding and nucleon
correlations through a relativistic nucleon spectral function. The
contributions of $\pi$ and $\rho$ mesons as well as shadowing effects are also
included.
  The beam energy loss is calculated using a phenomenological approach. The
present theoretical results are compared with the experimental results of E772
and E886 experiments. These results are applicable to the forthcoming
experimental analysis of E906 Sea Quest experiment at Fermi Lab.


title: Unsupervised Learning of Predictors from Unpaired Input-Output Samples

abstract:
  Unsupervised learning is the most challenging problem in machine learning and
especially in deep learning. Among many scenarios, we study an unsupervised
learning problem of high economic value --- learning to predict without costly
pairing of input data and corresponding labels. Part of the difficulty in this
problem is a lack of solid evaluation measures. In this paper, we take a
practical approach to grounding unsupervised learning by using the same success
criterion as for supervised learning in prediction tasks but we do not require
the presence of paired input-output training data. In particular, we propose an
objective function that aims to make the predicted outputs fit well the
structure of the output while preserving the correlation between the input and
the predicted output. We experiment with a synthetic structural prediction
problem and show that even with simple linear classifiers, the objective
function is already highly non-convex. We further demonstrate the nature of
this non-convex optimization problem as well as potential solutions. In
particular, we show that with regularization via a generative model, learning
with the proposed unsupervised objective function converges to an optimal
solution.


title:
Decentralized Supervisory Control of Networks of Nonlinear Control
  Systems

abstract:
  The paradigm of Cyber-Physical Systems of Systems (CPSoS) is becoming rather
popular in the control systems research community because of its expressive
power able to properly handle many engineered complex systems of interest.
Decentralized control techniques offer a promising approach in taming the
inherent complexity of CPSoS, also connected with the design of needed
communication infrastructures and computing units. In this paper, we propose
decentralized control of networks of discrete-time nonlinear control systems,
enforcing complex specifications expressed in terms of regular languages,
within any desired accuracy. As discussed in the paper, regular languages,
while being traditionally studied in the research community of discrete-event
systems, also provide a useful mean to model a rather wide variety of complex
specifications for control systems. The design of decentralized controllers is
based on formal methods and in particular, on the use of discrete abstractions.
Efficient synthesis of such controllers is derived by resorting to on-the-fly
algorithmic techniques that also allow the use of parallel computing
architectures. Advantages and disadvantages of the decentralized approach over
a centralized one, also in terms of computational complexity, are discussed. An
illustrative example is presented, which shows the applicability and
effectiveness of the results proposed.


title: A Study of MatchPyramid Models on Ad-hoc Retrieval

abstract:
  Deep neural networks have been successfully applied to many text matching
tasks, such as paraphrase identification, question answering, and machine
translation. Although ad-hoc retrieval can also be formalized as a text
matching task, few deep models have been tested on it. In this paper, we study
a state-of-the-art deep matching model, namely MatchPyramid, on the ad-hoc
retrieval task. The MatchPyramid model employs a convolutional neural network
over the interactions between query and document to produce the matching score.
We conducted extensive experiments to study the impact of different pooling
sizes, interaction functions and kernel sizes on the retrieval performance.
Finally, we show that the MatchPyramid models can significantly outperform
several recently introduced deep matching models on the retrieval task, but
still cannot compete with the traditional retrieval models, such as BM25 and
language models.


title: Trading Determinism for Time in Space Bounded Computations

abstract:
  Savitch showed in $1970$ that nondeterministic logspace (NL) is contained in
deterministic $\mathcal{O}(\log^2 n)$ space but his algorithm requires
quasipolynomial time. The question whether we can have a deterministic
algorithm for every problem in NL that requires polylogarithmic space and
simultaneously runs in polynomial time was left open.
  In this paper we give a partial solution to this problem and show that for
every language in NL there exists an unambiguous nondeterministic algorithm
that requires $\mathcal{O}(\log^2 n)$ space and simultaneously runs in
polynomial time.


title:
Optimization of the Multi-turn Injection Efficiency for Medical
  Synchrotron

abstract:
  We present a method for optimization of the multi-turn injection effciency
for medical synchrotron. We show that for given injection energy the injection
efficiency can be greatly enhanced by choosing transverse tunes appropriately
as well as optimizing the injection bump and the number of turns required for
beam injection. We verify our study by applying the method to the Korea Heavy
Ion Medical Accelerator (KHIMA) synchrotron which is currently built at the
campus of Dongnam Institute of Radiological and Medical Sciences (DIRAMS) in
Busan, Korea. First the frequency map analysis is performed with the help of
ELEGANT and ACCSIM codes. The tunes which yield the good injection efficiency
are then selected. With these tunes the injection bump and the number of turns
required for injection are then optimized by tracking a number of particles up
to one thousand turns after injection beyond which there is no further beam
loss. Results for optimization of the injection efficiency for proton ion are
presented.