title:
Composing Music with Grammar Argumented Neural Networks and Note-Level
  Encoding

abstract:
  Creating aesthetically pleasing pieces of art, including music, has been a
long-term goal for artificial intelligence research. Despite recent successes
of long-short term memory (LSTM) recurrent neural networks (RNNs) in sequential
learning, LSTM neural networks have not, by themselves, been able to generate
natural-sounding music conforming to music theory. To transcend this
inadequacy, we put forward a novel method for music composition that combines
the LSTM with Grammars motivated by music theory. The main tenets of music
theory are encoded as grammar argumented (GA) filters on the training data,
such that the machine can be trained to generate music inheriting the
naturalness of human-composed pieces from the original dataset while adhering
to the rules of music theory. Unlike previous approaches, pitches and durations
are encoded as one semantic entity, which we refer to as note-level encoding.
This allows easy implementation of music theory grammars, as well as closer
emulation of the thinking pattern of a musician. Although the GA rules are
applied to the training data and never directly to the LSTM music generation,
our machine still composes music that possess high incidences of diatonic scale
notes, small pitch intervals and chords, in deference to music theory.


title: Geometry of the moduli of parabolic bundles on elliptic curves

abstract:
  The goal of this paper is the study of simple rank 2 parabolic vector bundles
over a $2$-punctured elliptic curve $C$. We show that the moduli space of these
bundles is a non-separated gluing of two charts isomorphic to $\mathbb{P}^1
\times \mathbb{P}^1$. We also showcase a special curve $\Gamma$ isomorphic to
$C$ embedded in this space, and this way we prove a Torelli theorem.
  This moduli space is related to the moduli space of semistable parabolic
bundles over $\mathbb{P}^1$ via a modular map which turns out to be the 2:1
cover ramified in $\Gamma$. We recover the geometry of del Pezzo surfaces of
degree 4 and we reconstruct all their automorphisms via elementary
transformations of parabolic vector bundles.


title: VisualBackProp: efficient visualization of CNNs

abstract:
  This paper proposes a new method, that we call VisualBackProp, for
visualizing which sets of pixels of the input image contribute most to the
predictions made by the convolutional neural network (CNN). The method heavily
hinges on exploring the intuition that the feature maps contain less and less
irrelevant information to the prediction decision when moving deeper into the
network. The technique we propose was developed as a debugging tool for
CNN-based systems for steering self-driving cars and is therefore required to
run in real-time, i.e. it was designed to require less computations than a
forward propagation. This makes the presented visualization method a valuable
debugging tool which can be easily used during both training and inference. We
furthermore justify our approach with theoretical arguments and theoretically
confirm that the proposed method identifies sets of input pixels, rather than
individual pixels, that collaboratively contribute to the prediction. Our
theoretical findings stand in agreement with the experimental results. The
empirical evaluation shows the plausibility of the proposed approach on the
road video data as well as in other applications and reveals that it compares
favorably to the layer-wise relevance propagation approach, i.e. it obtains
similar visualization results and simultaneously achieves order of magnitude
speed-ups.


title: Investigating Factors Influencing the Latency of Cyberbullying Detection

abstract:
  Cyberbullying in online social networks has become a critical problem,
especially among teenagers who are social networks' prolific users. As a
result, researchers have focused on identifying distinguishing features of
cyberbullying and developing techniques to automatically detect cyberbullying
incidents. While this research has resulted in developing highly accurate
classifiers, two key practical issues related to identifying cyberbullying have
largely been ignored, namely scalability of cyberbullying detection services
and timeliness of raising alerts whenever a cyberbullying incident is
suspected.
  These two issues are the subject of this paper. We propose a multi-stage
cyberbullying detection solution that drastically reduces the classification
time and the time to raise cyberbullying alerts. The proposed solution is
highly scalable, does not sacrifice accuracy for scalability, and is highly
responsive in raising alerts. The solution is comprised of three novel
components, an initial predictor, a multilevel priority scheduler, and an
incremental classification mechanism. We have implemented this solution and
utilized data obtained from the Vine online social network to demonstrate the
utility of each of these components via a detailed performance evaluation. We
show that our complete solution is significantly more scalable and responsive
than the current state-of-the-art.


title: Strong approximation for the deviation of kernel copula estimators

abstract:
  We prove a uniform in bandwidth law of the iterated logarithm for the maximal
deviation of kernel copula estimators from their expectations. We deal
especially with the \textit{local linear}, the \textit{mirror-reflection} and
the \textit{transformation} estimators. These results are useful for
establishing the strong uniform in bandwidth consistency of these kernel
estimators.


title: A ghostly damped Ly$\alpha$ system revealed by metal absorption lines

abstract:
  We report the discovery of the first 'ghostly' damped Ly$\alpha$ absorption
system (DLA), which is identified by the presence of absorption from strong
low-ion species at $z_{\rm abs}=1.70465$ along the line of sight to the quasar
SDSSJ113341.29$-$005740.0 with $z_{\rm em}=1.70441$. No Ly$\alpha$ absorption
trough is seen associated with these absorptions because the DLA trough is
filled with the leaked emission from the broad emission line region of the
quasar. By modeling the quasar spectrum and analyzing the metal lines, we
derive log$N$(HI)(cm$^{-2}$)$\sim$21.0 $\pm$ 0.3. The DLA cloud is small ($\le$
0.32 pc) thus not covering entirely the broad line region and is located at
$\ge$ 39 pc from the central active galactic nucleus (AGN). Although the DLA is
slightly redshifted relative to the quasar, its metallicity
([S/H]=$-$0.41$\pm$0.30) is intermediate between what is expected from
infalling and outflowing gas. It could be possible that the DLA is part of some
infalling material accreting onto the quasar host galaxy through filaments, and
that its metallicity is raised by mixing with the enriched outflowing gas
emanating from the central AGN. Current DLA surveys miss these 'ghostly' DLAs,
and it would be important to quantify the statistics of this population by
searching the SDSS database using metal absorption templates.


title: On Stably Pointed Varieties and Generically Stable Groups in ACVF

abstract:
  We give a geometric description of the pair $(V,p)$, where $V$ is an affine
algebraic variety over a non-trivially valued algebraically closed field $K$
with valuation ring $\mathcal{O}_K$ and $p$ is a Zariski dense generically
stable type concentrated on $V$, by defining a fully faithful functor to the
category of schemes over $\mathcal{O}_K$ with residual dominant morphisms over
$\mathcal{O}_K$.
  We also study a maximum modulus principle on schemes over $\mathcal{O}_K$ and
show that the schemes obtained by this functor enjoy it.


title: Density of monochromatic infinite subgraphs

abstract:
  For any countably infinite graph $G$, Ramsey's theorem guarantees an infinite
monochromatic copy of $G$ in any $r$-coloring of the edges of the countably
infinite complete graph $K_\mathbb{N}$. Taking this a step further, it is
natural to wonder how "large" of a monochromatic copy of $G$ we can find with
respect to some measure -- for instance, the density (or upper density) of the
vertex set of $G$ in the positive integers. Unlike finite Ramsey theory, where
this question has been studied extensively, the analogous problem for infinite
graphs has been mostly overlooked.
  In one of the few results in the area, Erd\H{o}s and Galvin proved that in
every 2-coloring of $K_\mathbb{N}$, there exists a monochromatic path whose
vertex set has upper density at least $2/3$, but it is not possible to do
better than $8/9$. They also showed that for some sequence $\epsilon_n\to 0$,
there exists a monochromatic path $P$ such that for infinitely many $n$, the
set $\{1,2,...,n\}$ contains the first $(\frac{1}{3+\sqrt{3}}-\epsilon_n)n$
vertices of $P$, but it is not possible to do better than $2n/3$. We improve
both results, in the former case achieving an upper density at least $3/4$ and
in the latter case obtaining a tight bound of $2/3$. We also consider related
problems for directed paths, trees (connected subgraphs), and a more general
result which includes locally finite graphs for instance.


title:
Associative Embedding: End-to-End Learning for Joint Detection and
  Grouping

abstract:
  We introduce associative embedding, a novel method for supervising
convolutional neural networks for the task of detection and grouping. A number
of computer vision problems can be framed in this manner including multi-person
pose estimation, instance segmentation, and multi-object tracking. Usually the
grouping of detections is achieved with multi-stage pipelines, instead we
propose an approach that teaches a network to simultaneously output detections
and group assignments. This technique can be easily integrated into any
state-of-the-art network architecture that produces pixel-wise predictions. We
show how to apply this method to both multi-person pose estimation and instance
segmentation and report state-of-the-art performance for multi-person pose on
the MPII and MS-COCO datasets.


title: ProjE: Embedding Projection for Knowledge Graph Completion

abstract:
  With the large volume of new information created every day, determining the
validity of information in a knowledge graph and filling in its missing parts
are crucial tasks for many researchers and practitioners. To address this
challenge, a number of knowledge graph completion methods have been developed
using low-dimensional graph embeddings. Although researchers continue to
improve these models using an increasingly complex feature space, we show that
simple changes in the architecture of the underlying model can outperform
state-of-the-art models without the need for complex feature engineering. In
this work, we present a shared variable neural network model called ProjE that
fills-in missing information in a knowledge graph by learning joint embeddings
of the knowledge graph's entities and edges, and through subtle, but important,
changes to the standard loss function. In doing so, ProjE has a parameter size
that is smaller than 11 out of 15 existing methods while performing $37\%$
better than the current-best method on standard datasets. We also show, via a
new fact checking task, that ProjE is capable of accurately determining the
veracity of many declarative statements.


title:
Cs$_2$InAgCl$_6$: A new lead-free halide double perovskite with direct
  band gap

abstract:
  A$_2$BB$^\prime$X$_6$ halide double perovskites based on bismuth and silver
have recently been proposed as potential environmentally-friendly alternatives
to lead-based hybrid halide perovskites. In particular, Cs$_2$BiAgX$_6$ (X =
Cl, Br) have been synthesized and found to exhibit band gaps in the visible
range. However, the band gaps of these compounds are indirect, which is not
ideal for applications in thin film photovoltaics. Here, we propose a new class
of halide double perovskites, where the B$^{3+}$ and B$^{+}$ cations are
In$^{3+}$ and Ag$^{+}$, respectively. Our first-principles calculations
indicate that the hypothetical compounds Cs$_2$InAgX$_6$ (X = Cl, Br, I) should
exhibit direct band gaps between the visible (I) and the ultraviolet (Cl).
Based on these predictions, we attempt to synthesize Cs$_2$InAgCl$_6$ and
Cs$_2$InAgBr$_6$, and we succeed to form the hitherto unknown double perovskite
Cs$_2$InAgCl$_6$. X-ray diffraction yields a double perovskite structure with
space group $Fm\overline{3}m$. The measured band gap is 3.3 eV, and the
compound is found to be photosensitive and turns reversibly from white to
orange under ultraviolet illumination. We also perform an empirical analysis of
the stability of Cs$_2$InAgX$_6$ and their mixed halides based on Goldschmidt's
rules, and we find that it should also be possible to form
Cs$_2$InAg(Cl$_{1-x}$Br$_{x}$)$_6$ for $x<1$. The synthesis of mixed halides
will open the way to the development of lead-free double perovskites with
direct and tunable band gaps.


title: Inflexible $CR$ submanifolds

abstract:
  In this paper we introduce the concept of inflexible $CR$ submanifolds. These
are $CR$ submanifolds of some complex Euclidean space such that any compactly
supported $CR$ deformation is again globally $CR$ embeddable into some complex
Euclidean space. Our main result is that any $2$-pseudoconcave quadratic $CR$
submanifold of type $(n,d)$ in $\mathbb{C}^{n+d}$ is inflexible.


title:
Upscaledb: Efficient Integer-Key Compression in a Key-Value Store using
  SIMD Instructions

abstract:
  Compression can sometimes improve performance by making more of the data
available to the processors faster. We consider the compression of integer keys
in a B+-tree index. For this purpose, systems such as IBM DB2 use variable-byte
compression over differentially coded keys. We revisit this problem with
various compression alternatives such as Google's VarIntGB, Binary Packing and
Frame-of-Reference. In all cases, we describe algorithms that can operate
directly on compressed data. Many of our alternatives exploit the
single-instruction-multiple-data (SIMD) instructions supported by modern CPUs.
We evaluate our techniques in a database environment provided by Upscaledb, a
production-quality key-value database. Our best techniques are SIMD
accelerated: they simultaneously reduce memory usage while improving
single-threaded speeds. In particular, a differentially coded SIMD
binary-packing techniques (BP128) can offer a superior query speed (e.g., 40%
better than an uncompressed database) while providing the best compression
(e.g., by a factor of ten). For analytic workloads, our fast compression
techniques offer compelling benefits. Our software is available as open source.


title: New Hardness Results for Routing on Disjoint Paths

abstract:
  In the classical Node-Disjoint Paths (NDP) problem, the input consists of an
undirected $n$-vertex graph $G$, and a collection
$\mathcal{M}=\{(s_1,t_1),\ldots,(s_k,t_k)\}$ of pairs of its vertices, called
source-destination, or demand, pairs. The goal is to route the largest possible
number of the demand pairs via node-disjoint paths. The best current
approximation for the problem is achieved by a simple greedy algorithm, whose
approximation factor is $O(\sqrt n)$, while the best current negative result is
an $\Omega(\log^{1/2-\delta}n)$-hardness of approximation for any constant
$\delta$, under standard complexity assumptions. Even seemingly simple special
cases of the problem are still poorly understood: when the input graph is a
grid, the best current algorithm achieves an $\tilde O(n^{1/4})$-approximation,
and when it is a general planar graph, the best current approximation ratio of
an efficient algorithm is $\tilde O(n^{9/19})$. The best currently known lower
bound on the approximability of both these versions of the problem is
APX-hardness.
  In this paper we prove that NDP is $2^{\Omega(\sqrt{\log n})}$-hard to
approximate, unless all problems in NP have algorithms with running time
$n^{O(\log n)}$. Our result holds even when the underlying graph is a planar
graph with maximum vertex degree $3$, and all source vertices lie on the
boundary of a single face (but the destination vertices may lie anywhere in the
graph). We extend this result to the closely related Edge-Disjoint Paths
problem, showing the same hardness of approximation ratio even for sub-cubic
planar graphs with all sources lying on the boundary of a single face.


title:
Continuous globally exponential rigid-body angular velocity estimation
  from attitude measurements

abstract:
  A continuous solution is proposed to the problem of uniform global
exponential estimation of the angular velocity for rigid bodies by means of
direct attitude measurements. The proposed observer is designed on
$\mathbb{R}^3\times\mathbb{R}^3\times\mathbb{R}^3$, and not on the inherent
geometry $\mathtt{SO}(3)\times\mathbb{R}^3$, which allows for a simple
structure of the observer, being a copy of the system plus some correction
terms, and a straightforward classical Lyapunov stability proof. The
performances of the observer are illustrated by means of a simple simulation
scenario.


title: Aggregated Residual Transformations for Deep Neural Networks

abstract:
  We present a simple, highly modularized network architecture for image
classification. Our network is constructed by repeating a building block that
aggregates a set of transformations with the same topology. Our simple design
results in a homogeneous, multi-branch architecture that has only a few
hyper-parameters to set. This strategy exposes a new dimension, which we call
"cardinality" (the size of the set of transformations), as an essential factor
in addition to the dimensions of depth and width. On the ImageNet-1K dataset,
we empirically show that even under the restricted condition of maintaining
complexity, increasing cardinality is able to improve classification accuracy.
Moreover, increasing cardinality is more effective than going deeper or wider
when we increase the capacity. Our models, named ResNeXt, are the foundations
of our entry to the ILSVRC 2016 classification task in which we secured 2nd
place. We further investigate ResNeXt on an ImageNet-5K set and the COCO
detection set, also showing better results than its ResNet counterpart. The
code and models are publicly available online.


title:
Fractional quantum Hall effect in strained graphene: stability of
  Laughlin states in disordered (pseudo)magnetic fields

abstract:
  We address the question of the stability of the (fractional) quantum Hall
effect (QHE) in presence of pseudomagnetic disorder generated by mechanical
deformations of a graphene sheet. Neglecting the potential disorder and taking
into account only strain-induced random pseudomagnetic fields, it is possible
to write down a Laughlin-like trial ground-state wave function explicitly.
Exploiting the Laughlin plasma analogy, we demonstrate that in the case of
fluctuating pseudomagnetic fluxes of relatively small amplitude both the
integer and fractional quantum Hall effects are always stable upon the
deformations. By contrast, in the case of bubble-induced pseudomagnetic fields
in graphene on a substrate (a small number of large fluxes) the disorder can be
strong enough to cause a glass transition in the corresponding classical
Coulomb plasma, resulting in the destruction of fractional quantum Hall regime
and in a quantum phase transition to a non-ergodic state of the lowest Landau
level.


title:
ROS Regression: Integrating Regularization and Optimal Scaling
  Regression

abstract:
  In this paper we combine two important extensions of ordinary least squares
regression: regularization and optimal scaling. Optimal scaling (sometimes also
called optimal scoring) has originally been developed for categorical data, and
the process finds quantifications for the categories that are optimal for the
regression model in the sense that they maximize the multiple correlation.
Although the optimal scaling method was developed initially for variables with
a limited number of categories, optimal transformations of continuous variables
are a special case. We will consider a variety of transformation types;
typically we use step functions for categorical variables, and smooth (spline)
functions for continuous variables. Both types of functions can be restricted
to be monotonic, preserving the ordinal information in the data. In addition to
optimal scaling, three regularization methods will be considered: Ridge
regression, the Lasso, and the Elastic Net. The resulting method will be called
ROS Regression (Regularized Optimal Scaling Regression. We will show that the
basic OS algorithm provides straightforward and efficient estimation of the
regularized regression coefficients, automatically gives the Group Lasso and
Blockwise Sparse Regression, and extends them with monotonicity properties. We
will show that Optimal Scaling linearizes nonlinear relationships between
predictors and outcome, and improves upon the condition of the predictor
correlation matrix, increasing (on average) the conditional independence of the
predictors. Alternative options for regularization of either regression
coefficients or category quantifications are mentioned. Extended examples are
provided.
  Keywords: Categorical Data, Optimal Scaling, Conditional Independence, Step
Functions, Splines, Monotonic Transformations, Regularization, Lasso, Elastic
Net, Group Lasso, Blockwise Sparse Regression.


title: Self-accelerating Parabolic Cylinder Waves in 1-D

abstract:
  We introduce a new self-accelerating wave packet solution of the Schrodinger
equation in one dimension. We obtain an exact analytical parabolic cylinder
wave for the inverted harmonic potential. We show that truncated parabolic
cylinder waves exhibits their accelerating feature.


title: Convolutional Gated Recurrent Networks for Video Segmentation

abstract:
  Semantic segmentation has recently witnessed major progress, where fully
convolutional neural networks have shown to perform well. However, most of the
previous work focused on improving single image segmentation. To our knowledge,
no prior work has made use of temporal video information in a recurrent
network. In this paper, we introduce a novel approach to implicitly utilize
temporal data in videos for online semantic segmentation. The method relies on
a fully convolutional network that is embedded into a gated recurrent
architecture. This design receives a sequence of consecutive video frames and
outputs the segmentation of the last frame. Convolutional gated recurrent
networks are used for the recurrent part to preserve spatial connectivities in
the image. Our proposed method can be applied in both online and batch
segmentation. This architecture is tested for both binary and semantic video
segmentation tasks. Experiments are conducted on the recent benchmarks in
SegTrack V2, Davis, CityScapes, and Synthia. Using recurrent fully
convolutional networks improved the baseline network performance in all of our
experiments. Namely, 5% and 3% improvement of F-measure in SegTrack2 and Davis
respectively, 5.7% improvement in mean IoU in Synthia and 3.5% improvement in
categorical mean IoU in CityScapes. The performance of the RFCN network depends
on its baseline fully convolutional network. Thus RFCN architecture can be seen
as a method to improve its baseline segmentation network by exploiting
spatiotemporal information in videos.


title: Tessellating cushions: four-point functions in N=4 SYM

abstract:
  We consider a class of planar tree-level four-point functions in N=4 SYM in a
special kinematic regime: one BMN operator with two scalar excitations and
three half-BPS operators are put onto a line in configuration space;
additionally, for the half-BPS operators a co-moving frame is chosen in flavour
space. In configuration space, the four-punctured sphere is naturally
triangulated by tree-level planar diagrams. We demonstrate on a number of
examples that each tile can be associated with a modified hexagon form-factor
in such a way as to efficiently reproduce the tree-level four-point function.
Our tessellation is not of the OPE type, fostering the hope of finding an
independent, integrability-based approach to the computation of planar
four-point functions.


title: Stellar Populations of Shell Galaxies

abstract:
  We present a study of the inner (out to $\sim$1 R$_{\mathrm{eff}}$) stellar
populations of 9 shell galaxies. We derive stellar population parameters from
long slit spectra by both analyzing the Lick indices of the galaxies and by
fitting Single Stellar Population model spectra to the full galaxy spectra. The
results from the two methods agree reasonably well. Many of the shell galaxies
in our sample appear to have lower central $\mathrm{Mg}_{2}$ index values than
non-shell galaxies of the same central velocity dispersion, which is likely due
to a past interaction event. Our shell galaxy sample shows a relation between
central metallicity and velocity dispersion that is consistent with previous
samples of non-shell galaxies. Analyzing the metallicity gradients in our
sample, we find an average metallicity gradient of -0.16$\pm$0.10 dex per
decade in radius. We compare this with formation models to constrain the
merging history of shell galaxies. We argue that our galaxies likely have
undergone major mergers in their past but it is unclear whether the shells
formed from these events or from separate minor mergers. Additionally, we find
evidence for young stellar populations ranging in age from 500 Myr to 4--5 Gyr
in four of the galaxies, allowing us to speculate on the age of the shells. For
NGC 5670, we use a simple dynamical model to find the time required to produce
the observed distribution of shells to be consistent with the age of the young
subpopulation, suggesting that the shells likely formed from the same event
that led to the young subpopulation.


title:
An Efficient Framework for Floor-plan Prediction of Dynamic Runtime
  Reconfigurable Systems

abstract:
  Several embedded application domains for reconfigurable systems tend to
combine frequent changes with high performance demands of their workloads such
as image processing, wearable computing and network processors. Time
multiplexing of reconfigurable hardware resources raises a number of new
issues, ranging from run-time systems to complex programming models that
usually form a Reconfigurable hardware Operating System (ROS). The Operating
System performs online task scheduling and handles resource management. There
are many challenges in adaptive computing and dynamic reconfigurable systems.
One of the major understudied challenges is estimating the required resources
in terms of soft cores, Programmable Reconfigurable Regions (PRRs), the
appropriate communication infrastructure, and to predict a near optimal layout
and floorplan of the reconfigurable logic fabric. Some of these issues are
specific to the application being designed, while others are more general and
relate to the underlying run-time environment. Static resource allocation for
Run- Time Reconfiguration (RTR) often leads to inferior and unacceptable
results. In this paper, we present a novel adaptive and dynamic methodology,
based on a Machine Learning approach, for predicting and estimating the
necessary resources for an application based on past historical information. An
important feature of the proposed methodology is that the system is able to
learn and generalize and, therefore, is expected to improve its accuracy over
time. The goal of the entire process is to extract useful hidden knowledge from
the data. This knowledge is the prediction and estimation of the necessary
resources for an unknown or not previously seen application.


title: Recent developments on noncommutative motives

abstract:
  This survey covers some of the recent developments on noncommutative motives
and their applications. Among other topics, we compute the additive invariants
of relative cellular spaces and orbifolds; prove Kontsevich's semi-simplicity
conjecture; prove a far-reaching noncommutative generalization of the Weil
conjectures; prove Grothendieck's standard conjectures of type C+ and D,
Voevodsky's nilpotence conjecture, and Tate's conjecture, in several new cases;
embed the (cohomological) Brauer group into secondary K-theory; construct a
noncommutative motivic Gysin triangle; compute the localizing A1-homotopy
invariants of corner skew Laurent polynomial algebras and of noncommutative
projective schemes; relate Kontsevich's category of noncommutative mixed
motives to Morel-Voevodsky's stable A1-homotopy category, to Voevodsky's
triangulated category of mixed motives, and to Levine's triangulated category
of mixed motives; prove the Schur-finiteness conjecture for quadric fibrations
over low-dimensional bases; and finally extend Grothendieck's theory of periods
to the setting of dg categories.


title:
Reduction of electron repulsion and enhancement of $T_{c}$ in small
  diffusive superconducting grains

abstract:
  The superconducting properties of small metallic grains has been a topic of
active research for half a century now. Early experiments demonstrated a
remarkable rise in the critical temperature, $T_{c}$, with reducing grain size
in a variety of materials. In two dimensional diffusive superconductors,
$T_{c}$ is decreased due to enhanced Coulomb repulsion. We propose that in
finite size grains, the diffusive enhancement of the Coulomb repulsion is
weakened and leads ultimately to an increase in $T_{c}$ in isolated, disordered
two dimensional grains. Our mechanism is superimposed on the possible
enhancement in $T_{c}$ due to the change in the density of states of finite
size systems.


title: Ideals of partial differential equations

abstract:
  We propose a new algebraic approach to study compatibility of partial
differential equations. The approach uses concepts from commutative algebra,
algebraic geometry and Gr\"obner bases to clarify crucial notions concerning
compatibility such as passivity (involution) and reducibility. One obtains
sufficient conditions for a differential system to be passive and prove that
such systems generate manifolds in the jet space. Some examples of
constructions of passive systems associated with the sinh-Gordon equation are
given.


title:
Vanishing Pseudo Schur Complements, Reverse Order Laws, Absorption Laws
  and Inheritance Properties

abstract:
  The problem of when the vanishing of a (generalized) Schur complement of a
block matrix (corresponding to the leading principal subblock) implies that the
other (generalized) Schur complement (corresponding to the trailing principal
subblock) is zero, is revisited. A simple proof is presented. Absorption laws
for two important classes of generalized inverses are considered next.
Inheritance properties of the generalized Schur compements in relation to the
absorption laws are derived. Inheritance by the generalized principal pivot
transform is also studied.


title:
Bridging the Gap between Individuality and Joint Improvisation in the
  Mirror Game

abstract:
  Extensive experiments in Human Movement Science suggest that solo motions are
characterized by unique features that define the individuality or motor
signature of people. While interacting with others, humans tend to
spontaneously coordinate their movement and unconsciously give rise to joint
improvisation. However, it has yet to be shed light on the relationship between
individuality and joint improvisation. By means of an ad-hoc virtual agent, in
this work we uncover the internal mechanisms of the transition from solo to
joint improvised motion in the mirror game, a simple yet effective paradigm for
studying interpersonal human coordination. According to the analysis of
experimental data, normalized segments of velocity in solo motion are regarded
as individual motor signature, and the existence of velocity segments
possessing a prescribed signature is theoretically guaranteed. In this work, we
first develop a systematic approach based on velocity segments to generate
\emph{in-silico} trajectories of a given human participant playing solo. Then
we present an online algorithm for the virtual player to produce joint
improvised motion with another agent while exhibiting some desired kinematic
characteristics, and to account for movement coordination and mutual adaptation
during joint action tasks. Finally, we demonstrate that the proposed approach
succeeds in revealing the kinematic features transition from solo to joint
improvised motions, thus revealing the existence of a tight relationship
between individuality and joint improvisation.


title:
Spectral hole lifetimes and spin population relaxation dynamics in
  neodymium-doped yttrium orthosilicate

abstract:
  We present a detailed study of the lifetime of optical spectral holes due to
population storage in Zeeman sublevels of Nd$^{3+}$:Y$_2$SiO$_5$. The lifetime
is measured as a function of magnetic field strength and orientation,
temperature and Nd$^{3+}$ doping concentration. At the lowest temperature of 3
K we find a general trend where the lifetime is short at low field strengths,
then increases to a maximum lifetime at a few hundreds of mT, and then finally
decays rapidly for high field strengths. This behaviour can be modelled with a
relaxation rate dominated by Nd$^{3+}$-Nd$^{3+}$ cross relaxation at low fields
and spin lattice relaxation at high magnetic fields. The maximum lifetime
depends strongly on both the field strength and orientation, due to the
competition between these processes and their different angular dependencies.
The cross relaxation limits the maximum lifetime for concentrations as low as
30 ppm of Nd$^{3+}$ ions. By decreasing the concentration to less than 1 ppm we
could completely eliminate the cross relaxation, reaching a lifetime of 3.8 s
at 3~K. At higher temperatures the spectral hole lifetime is limited by the
magnetic-field independent Raman and Orbach processes. In addition we show that
the cross relaxation rate can be strongly reduced by creating spectrally large
holes of the order of the optical inhomogeneous broadening. Our results are
important for the development and design of new rare-earth-ion doped crystals
for quantum information processing and narrow-band spectral filtering for
biological tissue imaging.


title: Perturbative Higgs CP violation, unitarity and phenomenology

abstract:
  Perturbative probability conservation provides a strong constraint on the
presence of new interactions of the Higgs boson. In this work we consider CP
violating Higgs interactions in conjunction with unitarity constraints in the
gauge-Higgs and fermion-Higgs sectors. Injecting signal strength measurements
of the recently discovered Higgs boson allows us to make concrete and
correlated predictions of how CP-violation in the Higgs sector can be directly
constrained through collider searches for either characteristic new states or
tell-tale enhancements in multi-Higgs processes.


title:
Galactic synchrotron emissivity measurements between 250{\deg} < l <
  355{\deg} from the GLEAM survey with the MWA

abstract:
  Synchrotron emission pervades the Galactic plane at low radio frequencies,
originating from cosmic ray electrons interacting with the Galactic magnetic
field. Using a low-frequency radio telescope, the Murchison Widefield Array
(MWA), we measure the free-free absorption of this Galactic synchrotron
emission by intervening HII regions along the line of sight. These absorption
measurements allow us to calculate the Galactic cosmic-ray electron emissivity
behind and in front of 47 detected HII regions in the region $250^\circ < l <
355^\circ$, $|b| < 2^\circ$. We find that all average emissivities between the
HII regions and the Galactic edge along the line of sight ($\epsilon_b$) are in
the range of 0.24$\,\,\sim\,\,$0.70$\,\,$K$\,\,$pc$^{-1}$ with a mean of
0.40$\,\,$K$\,\,$pc$^{-1}$ and a variance of 0.10$\,\,$K$\,\,$pc$^{-1}$ at
88$\,\,$MHz. Our best model, the Two-circle model, divides the Galactic disk
into three regions using two circles centring on the Galactic centre. It shows
a high emissivity region near the Galactic centre, a low emissivity region near
the Galactic edge, and a medium emissivity region between these two regions,
contrary to the trend found by previous studies.


title: Inhomogeneous Cosmology with Numerical Relativity

abstract:
  We perform three-dimensional numerical relativity simulations of homogeneous
and inhomogeneous expanding spacetimes, with a view towards quantifying
non-linear effects from cosmological inhomogeneities. We demonstrate
fourth-order convergence with errors less than one part in 10^6 in evolving a
flat, dust Friedmann-Lemaitre-Roberston-Walker (FLRW) spacetime using the
Einstein Toolkit within the Cactus framework. We also demonstrate agreement to
within one part in 10^3 between the numerical relativity solution and the
linear solution for density, velocity and metric perturbations in the Hubble
flow over a factor of ~350 change in scale factor (redshift). We simulate the
growth of linear perturbations into the non-linear regime, where effects such
as gravitational slip and tensor perturbations appear. We therefore show that
numerical relativity is a viable tool for investigating nonlinear effects in
cosmology.


title: Diverse Stellar Haloes in Nearby Milky Way-Mass Disc Galaxies

abstract:
  We have examined the resolved stellar populations at large galactocentric
distances along the minor axis (from 10 kpc up to between 40 and 75 kpc), with
limited major axis coverage, of six nearby highly-inclined Milky Way-mass disc
galaxies using HST data from the GHOSTS survey. We select red giant branch
stars to derive stellar halo density profiles. The projected minor axis density
profiles can be approximated by power laws with projected slopes of between
$-2$ and $-3.7$ and a diversity of stellar halo masses of $1-6\times
10^{9}M_{\odot}$, or $2-14\%$ of the total galaxy stellar masses. The typical
intrinsic scatter around a smooth power law fit is $0.05-0.1$ dex owing to
substructure. By comparing the minor and major axis profiles, we infer
projected axis ratios $c/a$ at $\sim 25$ kpc between $0.4-0.75$. The GHOSTS
stellar haloes are diverse, lying between the extremes charted out by the
(rather atypical) haloes of the Milky Way and M31. We find a strong correlation
between the stellar halo metallicities and the stellar halo masses. We compare
our results with cosmological models, finding good agreement between our
observations and accretion-only models where the stellar haloes are formed by
the disruption of dwarf satellites. In particular, the strong observed
correlation between stellar halo metallicity and mass is naturally reproduced.
Low-resolution hydrodynamical models have unrealistically high stellar halo
masses. Current high-resolution hydrodynamical models appear to predict stellar
halo masses somewhat higher than observed but with reasonable metallicities,
metallicity gradients and density profiles.


title: Quantum Estimation of Parameters of Classical Spacetimes

abstract:
  We describe a quantum limit to measurement of classical spacetimes.
Specifically, we formulate a quantum Cramer-Rao lower bound for estimating the
single parameter in any one-parameter family of spacetime metrics. We employ
the locally covariant formulation of quantum field theory in curved spacetime,
which allows for a manifestly background-independent derivation. The result is
an uncertainty relation that applies to all globally hyperbolic spacetimes.
Among other examples, we apply our method to detection of gravitational waves
using the electromagnetic field as a probe, as in laser-interferometric
gravitational-wave detectors. Other applications are discussed, from
terrestrial gravimetry to cosmology.


title: Symmetry protected topological order at nonzero temperature

abstract:
  We address the question of whether symmetry-protected topological (SPT) order
can persist at nonzero temperature, with a focus on understanding the thermal
stability of several models studied in the theory of quantum computation. We
present three results in this direction. First, we prove that nontrivial SPT
order protected by a global on-site symmetry cannot persist at nonzero
temperature, demonstrating that several quantum computational structures
protected by such on-site symmetries are not thermally stable. Second, we prove
that the 3D cluster state model used in the formulation of topological
measurement-based quantum computation possesses a nontrivial SPT-ordered
thermal phase when protected by a global generalized (1-form) symmetry. The SPT
order in this model is detected by long-range localizable entanglement in the
thermal state, which compares with related results characterizing SPT order at
zero temperature in spin chains using localizable entanglement as an order
parameter. Our third result is to demonstrate that the high error tolerance of
this 3D cluster state model for quantum computation, even without a protecting
symmetry, can be understood as an application of quantum error correction to
effectively enforce a 1-form symmetry.


title:
Cosmic Web of Galaxies in the COSMOS Field: Public Catalog and Different
  Quenching for Centrals and Satellites

abstract:
  We use a mass complete (log($M/M_{\odot}$) $\geqslant$ 9.6) sample of
galaxies with accurate photometric redshifts in the COSMOS field to construct
the density field and the cosmic web to $z$=1.2. The comic web extraction
relies on the density field Hessian matrix and breaks the density field into
clusters, filaments and the field. We provide the density field and cosmic web
measures to the community. We show that at $z$ $\lesssim$ 0.8, the median
star-formation rate (SFR) in the cosmic web gradually declines from the field
to clusters and this decline is especially sharp for satellites ($\sim$ 1 dex
vs. $\sim$ 0.5 dex for centrals). However, at $z$ $\gtrsim$ 0.8, the trend
flattens out for the overall galaxy population and satellites. For star-forming
galaxies only, the median SFR is constant at $z$ $\gtrsim$ 0.5 but declines by
$\sim$ 0.3-0.4 dex from the field to clusters for satellites and centrals at
$z$ $\lesssim$ 0.5. We argue that for satellites, the main role of the cosmic
web environment is to control their star-forming fraction, whereas for
centrals, it is mainly to control their overall SFR at $z$ $\lesssim$ 0.5 and
to set their fraction at $z$ $\gtrsim$ 0.5. We suggest that most satellites
experience a rapid quenching mechanism as they fall from the field into
clusters through filaments, whereas centrals mostly undergo a slow
environmental quenching at $z$ $\lesssim$ 0.5 and a fast mechanism at higher
redshifts. Our preliminary results highlight the importance of the large-scale
cosmic web on galaxy evolution.


title: Observable properties of strong gravitational lenses

abstract:
  It is shown which properties of a strong gravitational lens can in principle
be recovered from observations of multiple extended images when no assumptions
are made about the deflector or sources. The mapping between individual
multiple images is identified as the carrier of information about the
gravitational lens and it is shown how this information can be extracted from a
hypothetical observation. The derivatives of the image map contain information
about convergence ratios and reduced shears over the regions of the multiple
images. For two observed images, it is not possible to reconstruct the
convergence ratio and shear at the same time. For three observed images, it is
possible to recover the convergence ratios and reduced shears identically. For
four or more observed images, the system of constraints is overdetermined, but
the same quantities can theoretically be recovered.


title: Signatures of Earth-scattering in the direct detection of Dark Matter

abstract:
  Direct detection experiments search for the interactions of Dark Matter (DM)
particles with nuclei in terrestrial detectors. But if these interactions are
sufficiently strong, DM particles may scatter in the Earth, affecting their
distribution in the lab. We present a new analytic calculation of this
`Earth-scattering' effect in the regime where DM particles scatter at most once
before reaching the detector. We perform the calculation self-consistently,
taking into account not only those particles which are scattered away from the
detector, but also those particles which are deflected towards the detector.
Taking into account a realistic model of the Earth and allowing for a range of
DM-nucleon interactions, we present the EarthShadow code, which we make
publicly available, for calculating the DM velocity distribution after
Earth-scattering. Focusing on low-mass DM, we find that Earth-scattering
reduces the direct detection rate at certain detector locations while
increasing the rate in others. The Earth's rotation induces a daily modulation
in the rate, which we find to be highly sensitive to the detector latitude and
to the form of the DM-nucleon interaction. These distinctive signatures would
allow us to unambiguously detect DM and perhaps even identify its interactions
in regions of the parameter space within the reach of current and future
experiments.


title:
Quantum spin liquid ground states of the Heisenberg-Kitaev model on the
  triangular lattice

abstract:
  We study quantum disordered ground states of the two dimensional
Heisenberg-Kitaev model on the triangular lattice using a Schwinger boson
approach. Our aim is to identify and characterize potential gapped quantum spin
liquid phases that are stabilized by anisotropic Kitaev interactions. For
antiferromagnetic Heisenberg- and Kitaev couplings and sufficiently small spin
$S$ we find three different symmetric $Z_2$ spin liquid phases, separated by
two continuous quantum phase transitions. Interestingly, the gap of elementary
excitations remains finite throughout the transitions. The first spin liquid
phase corresponds to the well known zero-flux state in the Heisenberg limit,
which is stable with respect to small Kitaev couplings and develops $120^\circ$
order in the semi-classical limit at large $S$. In the opposite Kitaev limit we
find a different spin liquid ground-state, which is a quantum disordered
version of a magnetically ordered state with antiferromagnetic chains, in
accordance with results in the classical limit. Finally, at intermediate
couplings we find a spin liquid state with unconventional spin correlations.
Upon spinon condensation this state develops Bragg peaks at incommensurate
momenta in close analogy to the magnetically ordered Z2 vortex crystal phase,
which has been analyzed in recent theoretical works.


title: AGN Heating in Simulated Cool-Core Clusters

abstract:
  We analyze heating and cooling processes in an idealized simulation of a
cool-core cluster, where momentum-driven AGN feedback balances radiative
cooling in a time-averaged sense. We find that, on average, energy dissipation
via shock waves is almost an order of magnitude higher than via turbulence.
Most of the shock waves in the simulation are very weak shocks with Mach
numbers smaller than 1.5, but the stronger shocks, although rare, dissipate
energy more effectively. We find that shock dissipation is a steep function of
radius, with most of the energy dissipated within 30 kpc, while radiative
cooling loses area less concentrated. However, adiabatic processes and mixing
(of post-shock materials and the surrounding gas) are able to redistribute the
heat throughout the core. A considerable fraction of the AGN energy also
escapes the core region. The cluster goes through cycles of AGN outbursts
accompanied by periods of enhanced precipitation and star formation, over Gyr
timescales. The cluster core is under-heated at the end of each cycle, but
over-heated at the peak of the AGN outburst. During the heating-dominant phase,
turbulent dissipation alone is often able to balance radiative cooling at every
radius but, when this is occurs, shock waves inevitably dissipate even more
energy. Our simulation explains why some clusters, such as Abell 2029, are
cooling dominated, while in some other clusters, such as Perseus, various
heating mechanisms including shock heating, turbulent dissipation and bubble
mixing can all individually balance cooling, and together, overheat the core.


title: A Study of Quasar Selection in the Dark Energy Survey Supernova fields

abstract:
  We present a study of quasar selection using the DES supernova fields. We
used a quasar catalog from an overlapping portion of the SDSS Stripe 82 region
to quantify the completeness and efficiency of selection methods involving
color, probabilistic modeling, variability, and combinations of
color/probabilistic modeling with variability. We only considered objects that
appear as point sources in the DES images. We examine color selection methods
based on the WISE mid-IR W1-W2 color, a mixture of WISE and DES colors (g-i and
i-W1) and a mixture of VHS and DES colors (g-i and i-K). For probabilistic
quasar selection, we used XDQSOz, an algorithm that employs an empirical
multi-wavelength flux model of quasars to assign quasar probabilities. Our
variability selection uses the multi-band chi2-probability that sources are
constant in the DES Year 1 griz-band light curves. The completeness and
efficiency are calculated relative to an underlying sample of point sources
that are detected in the required selection bands and pass our data quality and
photometric error cuts. We conduct our analyses at two magnitude limits, i<19.8
mag and i<22 mag. For sources with W1 and W2 detections, the W1-W2 color or
XDQSOz method combined with variability gives the highest completenesses of
>85% for both i-band magnitude limits and efficiencies of >80% to the bright
limit and >60% to the faint limit; however, the giW1 and giW1+variability
methods give the highest quasar surface densities. The XDQSOz method and
combinations of W1W2/giW1/XDQSOz with variability are among the better
selection methods when both high completeness and high efficiency are desired.
We also present the OzDES Quasar Catalog of 1,263 spectroscopically-confirmed
quasars taken by the OzDES survey. The catalog includes quasars with redshifts
up to z~4 and brighter than i=22 mag, although the catalog is not complete up
this magnitude limit.


title:
Galaxy clustering dependence on the
  $\left[\mathrm{O\scriptsize{II}}\right]$ emission line luminosity in the
  local Universe

abstract:
  We study the galaxy clustering dependence on the
$\left[\mathrm{O\scriptsize{II}}\right]$ emission line luminosity in the SDSS
DR7 Main galaxy sample at mean redshift $z\sim0.1$. We select volume-limited
samples of galaxies with different $\left[\mathrm{O\scriptsize{II}}\right]$
luminosity thresholds and measure their projected, monopole and quadrupole
two-point correlation functions. We model these observations using the
1$h^{-1}\rm{Gpc}$ MultiDark Planck cosmological simulation and generate
light-cones with the SUrvey GenerAtoR algorithm. To interpret our results, we
adopt a modified (Sub)Halo Abundance Matching scheme, accounting for the
stellar mass incompleteness of the emission line galaxies. The satellite
fraction constitutes an extra parameter in this model and allows to optimize
the clustering fit on both small and intermediate scales (i.e. $r_p\lesssim
30h^{-1}\rm{Mpc})$, with no need of any velocity bias correction. We find that,
in the local Universe, the $\left[\mathrm{O\scriptsize{II}}\right]$ luminosity
correlates with all the clustering statistics explored and with the galaxy
bias. This latter quantity correlates more strongly with the SDSS $r$-band
magnitude than $\left[\mathrm{O\scriptsize{II}}\right]$ luminosity. In
conclusion, we propose a straightforward method to produce reliable clustering
models, entirely built on the simulation products, which provides robust
predictions of the typical ELG host halo masses and satellite fraction values.
The SDSS galaxy data, MultiDark mock catalogues and clustering results are made
publicly available.


title: A Brownian Particle and Fields II: Radiation Reaction as an Application

abstract:
  Radiation reaction has been investigated traditionally in classical dynamics
and recently in non-linear QED for high-intensity field physics by
high-intensity lasers. The non-linearity of QED is predicted as the coupling
between a highly energetic electron and its radiation. However, the applicable
range of external fields in the previous method of the Furry picture is just
the case of a plane wave. In this Volume II, we aim the generalization of this
applicable range by using the stochastic scalar electron model introduced in
Volume I. We discuss the formulation of radiation reaction acting on a
stochastic scalar electron and show the origin of this non-linearity correction
in general conditions.


title: Quantum collision theory in flat bands

abstract:
  We consider quantum scattering of particles in media exhibiting strong
dispersion degeneracy. In particular, we study flat-banded lattices and
linearly dispersed energy bands. The former constitute a prime example of
single-particle frustration while the latter show degeneracy at the few- and
many-particle level. We investigate both impurity and two-body scattering and
show that, quite generally, scattering does not occur, which we relate to the
fact that transition matrices vanish on the energy shell. We prove that
scattering is instead replaced by projections onto band-projected eigenstates
of the interaction potential. We then use the general results to obtain
localised flat band states that are eigenstates of impurity potentials with
vanishing eigenvalues in one-dimensional flat bands and study the particular
case of a sawtooth lattice. We also uncover the relation between certain
solutions of one-dimensional systems that have been categorised as "strange",
and the scattering states in linearly dispersed continuum systems.


title: Multi-Boundary Entanglement in Chern-Simons Theory and Link Invariants

abstract:
  We consider Chern-Simons theory for gauge group $G$ at level $k$ on
3-manifolds $M_n$ with boundary consisting of $n$ topologically linked tori.
The Euclidean path integral on $M_n$ defines a quantum state on the boundary,
in the $n$-fold tensor product of the torus Hilbert space. We focus on the case
where $M_n$ is the link-complement of some $n$-component link inside the
three-sphere $S^3$. The entanglement entropies of the resulting states define
framing-independent link invariants which are sensitive to the topology of the
chosen link. For the Abelian theory at level $k$ ($G= U(1)_k$) we give a
general formula for the entanglement entropy associated to an arbitrary
$(m|n-m)$ partition of a generic $n$-component link into sub-links. The formula
involves the number of solutions to certain Diophantine equations with
coefficients related to the Gauss linking numbers (mod $k$) between the two
sublinks. This formula connects simple concepts in quantum information theory,
knot theory, and number theory, and shows that entanglement entropy between
sublinks vanishes if and only if they have zero Gauss linking (mod $k$). For $G
= SU(2)_k$, we study various two and three component links. We show that the
2-component Hopf link is maximally entangled, and hence analogous to a Bell
pair, and that the Whitehead link, which has zero Gauss linking, nevertheless
has entanglement entropy. Finally, we show that the Borromean rings have a
"W-like" entanglement structure (i.e., tracing out one torus does not lead to a
separable state), and give examples of other 3-component links which have
"GHZ-like" entanglement (i.e., tracing out one torus does lead to a separable
state).


title:
CoRoT 223992193: Investigating the variability in a low-mass, pre-main
  sequence eclipsing binary with evidence of a circumbinary disk

abstract:
  CoRoT 223992193 is the only known low-mass, pre-main sequence eclipsing
binary that shows evidence of a circumbinary disk. The system displays complex
photometric and spectroscopic variability over a range of timescales and
wavelengths. Using two optical CoRoT runs, and infrared Spitzer 3.6 and 4.5
$\mu$m observations (simultaneous with the second CoRoT run), we model the
out-of-eclipse light curves. The large scale structure in both CoRoT light
curves is consistent with the constructive and destructive interference of
starspot signals at two slightly different periods. Using the stellar $v\sin i$
's, we infer different rotation periods: the primary is consistent with
synchronisation and the secondary is slightly supersynchronous. Comparison of
the raw data to the residuals of our spot model in colour-magnitude space
indicates additional contributions consistent with variable dust emission and
obscuration. We also identify short-duration flux dips preceding secondary
eclipse in all three CoRoT and Spitzer bands. We construct a model of the inner
regions of the binary and propose that these dips could be caused by partial
occultation of the central binary by the accretion stream onto the primary
star. Analysis of 15 VLT/FLAMES H$\alpha$ profiles reveal an emission profile
associated with each star: the majority is consistent with chromospheric
emission but higher velocity emission is also seen, which could be due to
prominences or accretion-related phenomena. In addition, simultaneous u and
r-band observations from CFHT/MEGACam reveal a short-lived u-band excess
consistent with either an accretion hot spot or stellar flare. The photometric
and spectroscopic variations are complex but are consistent with the picture of
two active stars possibly undergoing non-steady, low-level accretion; the
system's very high inclination provides a new view of such variability.
[Abridged]


title:
Abundances of disk and bulge giants from hi-res optical spectra: I. O,
  Mg, Ca, and Ti in the Solar neighborhood and Kepler field samples

abstract:
  The galactic bulge is a significant part of our galaxy, but it is hard to
observe, being both distant and covered by dust in the disk. Therefore there do
not exist many hi-res optical spectra of bulge stars with large wavelength
coverage, whose determined abundances can be compared with nearby, similarly
analyzed stellar samples. We aim to determine the, for chemical evolution
models, so important alpha elements of a sample of bulge giants using hi-res
optical spectra with large wavelength coverage. The abundances found will be
compared to similarly derived abundances from similar spectra of similar stars
in the local thin and thick disks. In this first paper we focus on the Solar
neighborhood reference sample. We use spectral synthesis to derive the stellar
parameters as well as the elemental abundances of both the local as well as the
bulge samples of giants. Special care is taken to benchmark our method of
determining stellar parameters against independent measurements of effective
temperatures from angular diameter measurements and surface gravities from
asteroseismology. In this first paper we present the method used to determine
the stellar parameters as well as the elemental abundances, evaluate them, and
present the results for our local disk sample of 291 giants. When comparing our
determined spectroscopic temperatures to those derived from angular diameter
measurements, we reproduce these with a systematic difference of +10 K and a
standard deviation of 53 K. The spectroscopic gravities are reproducing the
ones determined from asteroseismology with a systematic offset of +0.10 dex and
a standard deviation of 0.12 dex. When it comes to the abundance trends, our
sample of local disk giants is closely following that of other works analyzing
solar neighborhood dwarfs, showing that the much brighter giant stars are as
good abundance probes as the often used dwarfs.


title: Higgs Boson Decay to Light Jets at the LHC

abstract:
  We study the Higgs boson $(h)$ decay to two light jets at the 14 TeV
High-Luminosity-LHC (HL-LHC), where a light jet ($j$) represents any non-flavor
tagged jet from the observational point of view. The decay mode $h\to gg$ is
chosen as the benchmark since it is the dominant channel in the Standard Model
(SM), but the bound obtained is also applicable to the light quarks
$(j=u,d,s)$. We estimate the achievable bounds on the decay branching fractions
through the associated production $Vh\ (V=W^\pm,Z)$. Events of the Higgs boson
decaying into heavy (tagged) or light (un-tagged) jets are correlatively
analyzed. We find that with 3000 fb$^{-1}$ data at the HL-LHC, we should expect
approximately $1\sigma$ statistical significance on the SM $Vh(gg)$ signal in
this channel. This corresponds to a reachable upper bound ${\rm BR}(h\to jj)
\leq 4~ {\rm BR}^{SM}(h\to gg)$ at $95\%$ confidence level. A consistency fit
also leads to an upper bound ${\rm BR}(h\to cc) < 15~ {\rm BR}^{SM}(h\to cc)$
at $95\%$ confidence level. The estimated bound may be further strengthened by
adopting multiple variable analyses, or adding other production channels.


title: Ferromagnetic order induced on graphene by Ni/Co proximity effects

abstract:
  We build a tight-binding Hamiltonian describing Co/Ni over graphene,
contemplating ATOP (a Co/Ni atom on top of each Carbon atom of one graphene
sublattice) and HCP (one Co/Ni atom per Graphene plaquette) configurations. For
the ATOP configuration the orbitals involved, for the Co/Ni, are the
$d_{z^2-r^2}$ which most strongly couple to one graphene sublattice and the
$d_{xz}$, $d_{yz}$ orbitals that couple directly to the second sublattice site.
Such configuration is diagonal in pseudo-spin and spin space, yielding electron
doping of the graphene and antiferro-magnetic ordering in the primitive cell in
agreement with DFT calculations. The second, HCP configuration is symmetric in
the graphene sublattices and only involves coupling to the $d_{xz}$, $d_{yz}$
orbitals. The register of the lattices in this case allows for a new coupling
between nearest neighbour sites, generating non-diagonal terms in the
pseudo-spin space and novel spin-kinetic couplings mimicking a spin-orbit
coupling generated by a magnetic coupling. The resulting proximity effect in
this case yields ferromagnetic order in the graphene substrate. We derive the
band structure in the vicinity of the K points for both configurations, the
Bloch wavefunctions and their spin polarization.


title: The Virasoro Gibbs state and BTZ black holes

abstract:
  We show that the Virasoro Gibbs state accurately describes the thermodynamics
of BTZ black holes at large temperatures and in the strong-coupling regime
$c<1$. We first give a simple heuristic argument by showing that at high
temperatures and arbitrary $c$, the energies are much larger than Planck mass.
Then we give a detailed analysis of the quantum fluctuations of the Gibbs state
on unitary irreducible representations of Virasoro group and explicitly show
that they go to zero in the high-temperature limit by means of representation
theory results. This implies the state has a sensible thermodynamic limit which
actually holds for any $c$. Finally, the matching with BTZ thermodynamics for
$c<1$ is obtained by using the known asymptotic behaviour of the characters of
the Virasoro discrete series. This result supports the idea that minimal models
could describe quantum gravity at strong coupling. We make no use of the
Euclidean path integral nor assume modular invariance of the partition
functions, although we comment on them along the way.


title: Sphalerons in composite and non-standard Higgs models

abstract:
  After the discovery of the Higgs boson and the rather precise measurement of
all electroweak boson's masses the local structure of the electroweak symmetry
breaking potential is already quite well established. However, despite being a
key ingredient to a fundamental understanding of the underlying mechanism of
electroweak symmetry breaking, the global structure of the electroweak
potential remains entirely unknown. The existence of sphalerons, unstable
solutions of the classical action of motion that are interpolating between
topologically distinct vacua, is a direct consequence of the Standard Model's
$\mathrm{SU}(2)_L$ gauge group. Nevertheless, the sphaleron energy depends on
the shape of the Higgs potential away from the minimum and can therefore be a
litmus test for its global structure. Focusing on two scenarios, the minimal
composite Higgs model $\mathrm{SO}(5)/\mathrm{SO}(4)$ or an elementary Higgs
with a deformed electroweak potential, we calculate the change of the sphaleron
energy compared to the Standard Model prediction. We find that the sphaleron
energy would have to be measured to $\mathcal{O}(10)\%$ accuracy to exclude
sizeable global deviations from the Standard Model Higgs potential. We further
find that because of the periodicity of the scalar potential in composite Higgs
models a second sphaleron branch with larger energy arises.


title:
Common Reconstructions in the Successive Refinement Problem with
  Receiver Side Information

abstract:
  We study a variant of the successive refinement problem with receiver side
information where the receivers require identical reconstructions. We present
general inner and outer bounds for the rate region for this variant and present
a single-letter characterization of the admissible rate region for several
classes of the joint distribution of the source and the side information. The
characterization indicates that the side information can be fully used to
reduce the communication rates via binning; however, the reconstruction
functions can depend only on the G\'acs-K\"orner common randomness shared by
the two receivers. Unlike existing (inner and outer) bounds to the rate region
of the general successive refinement problem, the characterization of the
admissible rate region derived for several settings of the variant studied
requires only one auxiliary random variable. Using the derived
characterization, we establish that the admissible rate region is not
continuous in the underlying source source distribution even though the problem
formulation does not involve zero-error or functional reconstruction
constraints.


title: Effects of Completeness and Purity on Cluster Dark Energy Constraints

abstract:
  The statistical properties of galaxy clusters can only be used for
cosmological purposes if observational effects related to cluster detection are
accurately characterized. These effects include the selection function
associated to cluster finder algorithms and survey strategy. The importance of
the selection becomes apparent when different cluster finders are applied to
the same galaxy catalog, producing different cluster samples. We consider
parametrized functional forms for the observable-mass relation, its scatter as
well as the completeness and purity of cluster samples, and study how prior
knowledge on these function parameters affects dark energy constraints derived
from cluster statistics. Under the assumption that completeness and purity
reach 50 % at masses around 10^{13.5} Msun/h, we find that self-calibration of
selection parameters in current and upcoming cluster surveys is possible, while
still allowing for competitive dark energy constraints. We consider a fiducial
survey with specifications similar to those of the Dark Energy Survey (DES)
with 5000 deg^2, maximum redshift of zmax ~ 1.0 and threshold observed mass
M_{th} ~ 10^{13.8} Msun/h, such that completeness and purity ~ 60 % - 80 % at
masses around M_{th}. Perfect knowledge of all selection parameters allows for
constraining a constant dark energy equation of state to sigma(w)=0.033.
Employing a joint fit including self-calibration of the effective selection
degrades constraints to sigma(w)=0.046. External calibrations at the level of 1
% in the parameters of the observable-mass relation and completeness/purity
functions are necessary to improve the joint constraints to sigma(w)=0.041. In
the lack of knowledge of selection parameters, future experiments probing
larger areas and greater depths suffer from stronger relative degradations on
dark energy constraints compared to current surveys.


title:
Embedding Projector: Interactive Visualization and Interpretation of
  Embeddings

abstract:
  Embeddings are ubiquitous in machine learning, appearing in recommender
systems, NLP, and many other applications. Researchers and developers often
need to explore the properties of a specific embedding, and one way to analyze
embeddings is to visualize them. We present the Embedding Projector, a tool for
interactive visualization and interpretation of embeddings.


title: Chiral magnetic plasmons in anomalous relativistic matter

abstract:
  The chiral plasmon modes of relativistic matter in background magnetic and
strain-induced pseudomagnetic fields are studied in detail using the consistent
chiral kinetic theory. The results reveal a number of anomalous features of
these chiral magnetic and pseudomagnetic plasmons that could be used to
identify them in experiment. In a system with nonzero electric (chiral)
chemical potential, the background magnetic (pseudomagnetic) fields not only
modify the values of the plasmon frequencies in the long-wavelength limit, but
also affect the qualitative dependence on the wave vector. Similar
modifications can be also induced by the chiral shift parameter in Weyl
materials. Interestingly, even in the absence of the chiral shift and external
fields, the chiral chemical potential alone leads to a splitting of plasmon
energies at linear order in the wave vector.


title:
Accessing transverse nucleon and gluon distributions in heavy nuclei
  using coherent vector meson photoproduction at high energies in ion
  ultraperipheral collisions

abstract:
  By using the theoretical approaches describing well the available data on
$t$-integrated coherent photoproduction of light and heavy vector mesons in
Pb-Pb ultraperipheral collisions (UPCs) at the Large Hadron Collider (LHC) in
Run 1, we calculate the momentum transfer distributions for this process for
$\rho$ and $J/\psi$ vector mesons in the kinematics of Run 2 at the LHC. We
demonstrate that nuclear shadowing not only suppresses the absolute value of
the cross sections, but also shifts the momentum transfer distributions toward
smaller values of the momentum transfer $|t|$. This result can be interpreted
as a broadening in the impact parameter space of the effective nucleon density
in nuclei by 14\% in the case of $\rho$ and the nuclear gluon distribution by
$5-11$\% in the case of $J/\psi$.


title: Global regularity for the 3D finite depth capillary water waves

abstract:
  In this paper, we prove global regularity, scattering, and the non-existence
of small traveling waves for the $3D$ finite depth capillary waves system for
small initial data. The non-existence of small traveling waves shows a
fundamental difference between the capillary waves ($\sigma=1, g=0$) and the
gravity-capillary waves ($\sigma=1,$ $ 0< g< 3$) in the finite depth setting.
As, for the later case, there exists arbitrary small $L^2$ traveling waves.
  Different from the water waves system in the infinite depth setting, the
quadratic terms of the same system in the finite depth setting are worse due to
the absence of null structure inside the Dirichlet-Neumann operator. In the
finite depth setting, the capillary waves system has the worst quadratic terms
among the water waves systems with all possible values of gravity effect
constant and surface tension coefficient. It loses favorable cancellations not
only in the High $\times$ Low type interaction but also in the High $\times $
High type interaction.
  In the worst scenario, the best decay rate of the nonlinear solution that one
could expect is $ (1+t) ^ {-1/2} $, because the $3D$ finite depth capillary
waves system lacks null structures and there exists $Q(u, \bar{u})$ type
quadratic term, which causes a very large time resonance set and the definite
growth of the associated profile. As a result, the problematic terms are not
only the quadratic terms but also the cubic terms.
  To prove global regularity for the capillary waves system, we identify a good
variable to prove the dispersion estimate, fully exploit the hidden structures
inside the capillary waves system, and use a novel method to control the
weighted norms.


title:
Doppler imaging of chemical spots on magnetic Ap/Bp stars. Numerical
  tests and assessment of systematic errors

abstract:
  Doppler imaging (DI) is a powerful spectroscopic inversion technique that
enables conversion of a line profile time series into a two-dimensional map of
the stellar surface inhomogeneities. In this paper we investigate the accuracy
of chemical abundance DI of Ap/Bp stars and assess the impact of several
different systematic errors on the reconstructed spot maps. We simulate
spectroscopic observational data for different spot distributions in the
presence of a moderately strong dipolar magnetic field. We then reconstruct
chemical maps using different sets of spectral lines and making different
assumptions about line formation in the inversion calculations. Our numerical
experiments demonstrate that a modern DI code successfully recovers the input
chemical spot distributions comprised of multiple circular spots at different
latitudes or an element overabundance belt at the magnetic equator. For the
optimal reconstruction the average reconstruction errors do not exceed ~0.10
dex. The errors increase to about 0.15 dex when abundance distributions are
recovered from a few and/or blended spectral lines. Ignoring a 2.5 kG dipolar
magnetic field in chemical abundance DI leads to an average relative error of
0.2 dex and maximum errors of 0.3 dex. Similar errors are encountered if a DI
inversion is carried out neglecting a non-uniform continuum brightness
distribution and variation of the local atmospheric structure. This series of
numerical DI simulations proves that inversions with simplifying assumptions of
the non-magnetic radiative transfer and a single model atmosphere are generally
reliable. We assess magnetic field strengths of several dozen Ap/Bp stars
previously studied with DI methods, concluding that the vast majority of the
published chemical spot maps are unaffected by the systematic errors addressed
in this paper. (Abridged)


title:
The Pattern Recognition of Probability Distributions of Amino acids in
  protein families

abstract:
  A pattern Recognition of a probability distribution of amino acids is
obtained for selected families of proteins. The mathematical model is derived
from a theory of protein families formation which is derived from application
of a Pauli's master equation method.


title:
The Bayesian Formulation and Well-Posedness of Fractional Elliptic
  Inverse Problems

abstract:
  We study the inverse problem of recovering the order and the diffusion
coefficient of an elliptic fractional partial differential equation from a
finite number of noisy observations of the solution. We work in a Bayesian
framework and show conditions under which the posterior distribution is given
by a change of measure from the prior. Moreover, we show well-posedness of the
inverse problem, in the sense that small perturbations of the observed solution
lead to small Hellinger perturbations of the associated posterior measures. We
thus provide a mathematical foundation to the Bayesian learning of the order
---and other inputs--- of fractional models.

categories: math.AP math.PR math.ST physics.data-an stat.TH


title:
Self-calibration-based Approach to Critical Motion Sequences of
  Rolling-shutter Structure from Motion

abstract:
  In this paper we consider critical motion sequences (CMSs) of rolling-shutter
(RS) SfM. Employing an RS camera model with linearized pure rotation, we show
that the RS distortion can be approximately expressed by two internal
parameters of an "imaginary" camera plus one-parameter nonlinear transformation
similar to lens distortion. We then reformulate the problem as self-calibration
of the imaginary camera, in which its skew and aspect ratio are unknown and
varying in the image sequence. In the formulation, we derive a general
representation of CMSs. We also show that our method can explain the CMS that
was recently reported in the literature, and then present a new remedy to deal
with the degeneracy. Our theoretical results agree well with experimental
results; it explains degeneracies observed when we employ naive bundle
adjustment, and how they are resolved by our method.


title: Low Barrier Nanomagnets as p-bits for Spin Logic

abstract:
  It has recently been shown that a suitably interconnected network of tunable
telegraphic noise generators or "p-bits" can be used to perform even precise
arithmetic functions like a 32-bit adder. In this paper we use simulations
based on the stochastic Landau-Lifshitz-Gilbert (sLLG) equation to demonstrate
that similar impressive functions can be performed using unstable nanomagnets
with energy barriers as low as a fraction of a kT. This is surprising since the
magnetization of low barrier nanomagnets is not telegraphic with discrete
values of +1 and -1. Rather it fluctuates randomly among all values between -1
and +1, and the output magnets are read with a thresholding device that
translates all positive values to 1 and all negative values to zero. We present
sLLG-based simulations demonstrating the operation of a 32-bit adder with a
network of several hundred nanomagnets, exhibiting a remarkably precise
correlation: The input magnets {A} and {B} as well as the output magnets {S}
all fluctuate randomly and yet the quantity A+B-S is sharply peaked around
zero! If we fix {A} and {B}, the sum magnets {S} rapidly converge to a unique
state with S=A+B so that the system acts as an adder. But unlike standard
adders, the operation is invertible. If we fix {S} and {B}, the remaining
magnets {A} converge to the difference A=S-B. These examples suggest a new
direction for the field of nanomagnetics away from stable high barrier magnets
towards stochastic low barrier magnets which not only operate with lower
currents, but are also more promising for continued downscaling.


title:
Vector-Like Quarks and Leptons, SU(5) $\otimes$ SU(5) Grand Unification,
  and Proton Decay

abstract:
  SU(5) $\otimes$ SU(5) provides a minimal grand unification scheme for
fermions and gauge forces if there are vector-like quarks and leptons in
nature. We explore the gauge coupling unification in a non-supersymmetric model
of this type, and study its implications for proton decay. The properties of
vector-like quarks and intermediate scales that emerge from coupling
unification play a central role in suppressing proton decay. We find that in
this model, the familiar decay mode $p \to e^+ \pi^0$ may have a partial
lifetime within the reach of currently planned experiments.


title: Probabilistic Fluorescence-Based Synapse Detection

abstract:
  Brain function results from communication between neurons connected by
complex synaptic networks. Synapses are themselves highly complex and diverse
signaling machines, containing protein products of hundreds of different genes,
some in hundreds of copies, arranged in precise lattice at each individual
synapse. Synapses are fundamental not only to synaptic network function but
also to network development, adaptation, and memory. In addition, abnormalities
of synapse numbers or molecular components are implicated in most mental and
neurological disorders. Despite their obvious importance, mammalian synapse
populations have so far resisted detailed quantitative study. In human brains
and most animal nervous systems, synapses are very small and very densely
packed: there are approximately 1 billion synapses per cubic millimeter of
human cortex. This volumetric density poses very substantial challenges to
proteometric analysis at the critical level of the individual synapse. The
present work describes new probabilistic image analysis methods for
single-synapse analysis of synapse populations in both animal and human brains.


title:
Solving Cold-Start Problem in Large-scale Recommendation Engines: A Deep
  Learning Approach

abstract:
  Collaborative Filtering (CF) is widely used in large-scale recommendation
engines because of its efficiency, accuracy and scalability. However, in
practice, the fact that recommendation engines based on CF require interactions
between users and items before making recommendations, make it inappropriate
for new items which haven't been exposed to the end users to interact with.
This is known as the cold-start problem. In this paper we introduce a novel
approach which employs deep learning to tackle this problem in any CF based
recommendation engine. One of the most important features of the proposed
technique is the fact that it can be applied on top of any existing CF based
recommendation engine without changing the CF core. We successfully applied
this technique to overcome the item cold-start problem in Careerbuilder's CF
based recommendation engine. Our experiments show that the proposed technique
is very efficient to resolve the cold-start problem while maintaining high
accuracy of the CF recommendations.


title:
Predicting the lattice thermal conductivity of solids by solving the
  Boltzmann transport equation: AFLOW - AAPL an automated, accurate and
  effcient framework

abstract:
  One of the most accurate approaches for calculating lattice thermal
conductivity, $\kappa_l$, is solving the Boltzmann transport equation starting
from third-order anharmonic force constants. In addition to the underlying
approximations of ab-initio parameterization, two main challenges are
associated with this path. High computational costs and lack of automation in
the frameworks using this methodology affect the discovery rate of novel
materials with ad-hoc properties. Here, we present the
Automatic-Anharmonic-Phonon-Library, AAPL. It efficiently computes interatomic
force constants by making effective use of crystal symmetry analysis, it solves
the Boltzmann transport equation to obtain $\kappa_l$, and allows a fully
integrated operation with minimum user intervention, a rational addition to the
current high-throughput accelerated materials development framework AFLOW. We
show an "experiment versus theory" study of the approach, we compare accuracy
and speed with respect to other available packages, and for materials
characterized by strong electron localization and correlation, we demonstrate
that it is possible to improve accuracy without increasing computational
requirements by combining AAPL with the pseudo-hybrid functional ACBN0.


title: A new estimate on complexity of binary generalized pseudostandard words

abstract:
  Generalized pseudostandard words were introduced by de Luca and De Luca in
2006. In comparison to the palindromic and pseudopalindromic closure, only
little is known about the generalized pseudopalindromic closure and the
associated generalized pseudostandard words. We present a counterexample to
Conjecture 43 from a paper by Blondin Mass\'e et al. that estimated the
complexity of binary generalized pseudostandard words as ${\mathcal C}(n) \leq
4n$ for all sufficiently large $n$. We conjecture that ${\mathcal C}(n)<6n$ for
all $n \in \mathbb N$.


title:
A Hybrid Quasi-Newton Projected-Gradient Method with Application to
  Lasso and Basis-Pursuit Denoise

abstract:
  We propose a new algorithm for the optimization of convex functions over a
polyhedral set in Rn. The algorithm extends the spectral projected-gradient
method with limited-memory BFGS iterates restricted to the present face
whenever possible. We prove convergence of the algorithm under suitable
conditions and apply the algorithm to solve the Lasso problem, and
consequently, the basis-pursuit denoise problem through the root-finding
framework proposed by van den Berg and Friedlander [SIAM Journal on Scientific
Computing, 31(2), 2008]. The algorithm is especially well suited to simple
domains and could also be used to solve bound-constrained problems as well as
problems restricted to the simplex.


title:
Algorithm for the solution of the Dirac equation on digital quantum
  computers

abstract:
  A quantum algorithm that solves the time-dependent Dirac equation on a
digital quantum computer is developed and analyzed. The time evolution is
performed by an operator splitting decomposition technique that allows for a
mapping of the Dirac operator to a quantum walk supplemented by unitary
rotation steps in spinor space. Every step of the splitting method is
decomposed into sets of quantum gates. It is demonstrated that the algorithm
has an exponential speedup over the implementation of the same numerical scheme
on a classical computer, as long as certain conditions are satisfied. Finally,
an explicit decomposition of this algorithm into elementary gates from a
universal set is carried out to determine the resource requirements. It is
shown that a proof-of-principle calculation may be possible with actual quantum
technologies.


title:
Analytical Approximate Solutions of Systems of Multi-pantograph Delay
  Differential Equations Using Residual Power-series Method

abstract:
  This paper investigates analytical approximate solutions for a system of
multipantograph delay differential equations using the residual power series
method (RPSM), which obtains a Taylor expansion of the solutions and produces
the exact form in terms of convergent series requires no linearization or small
perturbation when the solutions are polynomials. By this method, an excellent
approximate solution can be obtained with only a few iterations. In this sense,
computational results of some examples are presented to demonstrate the
viability, simplicity and practical usefulness of the method. In addition, the
results reveal that the proposed method is very effective, straightforward, and
convenient for solving a system of multi-pantograph delay differential
equations.


title:
Imaging the elusive H-poor gas in planetary nebulae with large abundance
  discrepancy factors

abstract:
  The discrepancy between abundances computed using optical recombination lines
(ORLs) and collisionally excited lines (CELs) is a major, unresolved problem
with significant implications for the determination of chemical abundances
throughout the Universe. In planetary nebulae (PNe), the most common
explanation for the discrepancy is that two different gas phases coexist: a hot
component with standard metallicity, and a much colder plasma enhanced in heavy
elements. This dual nature is not predicted by mass loss theories, and direct
observational support for it is still weak. In this work, we present our recent
findings that demonstrate that the largest abundance discrepancies are
associated with close binary central stars. OSIRIS-GTC tunable filter imaging
of the faint O II ORLs and MUSE-VLT deep 2D spectrophotometry confirm that O II
ORL emission is more centrally concentrated than that of [O III] CELs and,
therefore, that the abundance discrepancy may be closely linked to binary
evolution.


title: Algebraic multigrid support vector machines

abstract:
  The support vector machine is a flexible optimization-based technique widely
used for classification problems. In practice, its training part becomes
computationally expensive on large-scale data sets because of such reasons as
the complexity and number of iterations in parameter fitting methods,
underlying optimization solvers, and nonlinearity of kernels. We introduce a
fast multilevel framework for solving support vector machine models that is
inspired by the algebraic multigrid. Significant improvement in the running has
been achieved without any loss in the quality. The proposed technique is highly
beneficial on imbalanced sets. We demonstrate computational results on publicly
available and industrial data sets.


title:
On the regularity and partial regularity of extremal solutions of a
  Lane-Emden system

abstract:
  In this paper, we consider the system $-\Delta u =\lambda (v+1)^p,\;\;-\Delta
v = \gamma (u+1)^\theta$ on a smooth bounded domain $\Omega$ in $\mathbb{R}^N$
with the Dirichlet boundary condition $u=v=0$ on $\partial \Omega.$ Here $
\lambda,\gamma$ are positive parameters. Let $x_0$ be the largest root of the
polynomial \begin{equation*} H(x) = x^4 -
\frac{16p\theta(p+1)(\theta+1)}{(p\theta-1)^2}x^2 +
\frac{16p\theta(p+1)(\theta+1)(p+\theta+2)}{(p\theta-1)^3}x
-\frac{16p\theta(p+1)^2(\theta+1)^2}{(p\theta-1)^4}. \end{equation*} We show
that the extremal solutions associated to the above system are bounded provided
$N<2+2x_0.$ This improves the previous work in \cite{co1}. We also prove that,
if $N\geq 2+2x_0,$ then the singular set of any extremal solution has Hausdorff
dimension less or equal to $N-(2+2x_0).$


title:
Detection of High Energy Cosmic Rays at the Auger Engineering Radio
  Array

abstract:
  Detection of (ultra-) high-energy cosmic rays with the use of radio frequency
emission from extensive air showers has been proven as complimentary to
existing ground array detection techniques. Great progress has been made in the
understanding of the emission processes and in their Monte Carlo modelling.
These have led to experimental results, notably also at the Auger Engineering
Radio Array, on energy, angular and mass composition resolution of the primary
cosmic rays. Recent results are reported. The measured resolutions turn out to
be competitive with existing techniques and they have independent
uncertainties. Implications for cross-calibration with existing techniques and
for future large-scale applications of radio detection of ultra-high-energy
cosmic rays are discussed.

categories: astro-ph.IM astro-ph.HE hep-ex physics.ins-det


title: Semantic Regularisation for Recurrent Image Annotation

abstract:
  The "CNN-RNN" design pattern is increasingly widely applied in a variety of
image annotation tasks including multi-label classification and captioning.
Existing models use the weakly semantic CNN hidden layer or its transform as
the image embedding that provides the interface between the CNN and RNN. This
leaves the RNN overstretched with two jobs: predicting the visual concepts and
modelling their correlations for generating structured annotation output.
Importantly this makes the end-to-end training of the CNN and RNN slow and
ineffective due to the difficulty of back propagating gradients through the RNN
to train the CNN. We propose a simple modification to the design pattern that
makes learning more effective and efficient. Specifically, we propose to use a
semantically regularised embedding layer as the interface between the CNN and
RNN. Regularising the interface can partially or completely decouple the
learning problems, allowing each to be more effectively trained and jointly
training much more efficient. Extensive experiments show that state-of-the art
performance is achieved on multi-label classification as well as image
captioning.


title:
Dynamic chiral magnetic effect and Faraday rotation in macroscopically
  disordered helical metals

abstract:
  We develop an effective medium theory for electromagnetic wave propagation
through gapless non-uniform systems with dynamic chiral magnetic effect. The
theory allows to calculate macroscopic-disorder-induced corrections to the
values of optical, as well as chiral magnetic conductivities. In particular, we
show that spatial fluctuations of optical conductivity induce corrections to
the effective value of the chiral magnetic conductivity. Experimentally, these
corrections can be observed as sharp features in the Faraday rotation angle
near frequencies that correspond to the bulk plasmon resonances of a material.
Such features are not expected to be present in single crystal samples.


title: Collimation method studies for next-generation hadron colliders

abstract:
  In order to handle extremely-high stored energy in future proton-proton
colliders, an extremely high-efficiency collimation system is required for safe
operation. At LHC, the major limiting locations in terms of particle losses on
superconducting (SC) magnets are the dispersion suppressors (DS) downstream of
the transverse collimation insertion. These losses are due to the protons
experiencing single diffractive interactions in the primary collimators. How to
solve this problem is very important for future proton-proton colliders, such
as the FCC-hh and SPPC. In this article, a novel method is proposed, which
arranges both the transverse and momentum collimation in the same long straight
section. In this way, the momentum collimation system can clean those particles
related to the single diffractive effect. The effectiveness of the method has
been confirmed by multi-particle simulations. In addition, SC quadrupoles with
special designs such as enlarged aperture and good shielding are adopted to
enhance the phase advance in the transverse collimation section, so that
tertiary collimators can be arranged to clean off the tertiary halo which
emerges from the secondary collimators and improve the collimation efficiency.
With one more collimation stage in the transverse collimation, the beam losses
in both the momentum collimation section and the experimental regions can be
largely reduced. Multi-particle simulation results with the MERLIN code confirm
the effectiveness of the collimation method. At last, we provide a protection
scheme of the SC magnets in the collimation section. The FLUKA simulations show
that by adding some special protective collimators in front of the magnets, the
maximum power deposition in the SC coils is reduced dramatically, which is
proven to be valid for protecting the SC magnets from quenching.


title: Exotic RG Flows from Holography

abstract:
  Holographic RG flows are studied in an Einstein-dilaton theory with a general
potential. The superpotential formalism is utilized in order to characterize
and classify all solutions that are associated to asymptotically AdS
space-times. Such solutions correspond to holographic RG flows and are
characterized by their holographic $\beta$-functions. Novel solutions are found
that have exotic properties from a RG point-of view. Some have
$\beta$-functions that are defined patch-wise and lead to flows where the
$\beta$-function changes sign without the flow stopping. Others describe flows
that end in non-neighboring extrema in field space. Finally others describe
regular flows between two minima of the potential and correspond
holographically to flows driven by the VEV of an irrelevant operator in the UV
CFT.


title:
Balanced truncation and singular perturbation approximation model order
  reduction for stochastically controlled linear systems

abstract:
  When solving linear stochastic differential equations numerically, usually a
high order spatial discretisation is used. Balanced truncation (BT) and
singular perturbation approximation (SPA) are well-known projection techniques
in the deterministic framework which reduce the order of a control system and
hence reduce computational complexity. This work considers both methods when
the control is replaced by a noise term. We provide theoretical tools such as
stochastic concepts for reachability and observability, which are necessary for
balancing related model order reduction of linear stochastic differential
equations with additive L\'evy noise. Moreover, we derive error bounds for both
BT and SPA and provide numerical results for a specific example which support
the theory.


title:
Growth of Ni and Ni-Cr Alloy Thin Films on MgO(001): Effect of Alloy
  Composition on Surface Morphology

abstract:
  The effects of substrate treatment, temperature and composition on the
surface morphology of Ni-Cr thin films grown on MgO(001) are studied by
scanning tunneling microscopy (STM) and atomic force microscopy (AFM). A
combination of acid-etching and high temperature deposition (400C) will result
in smooth films and terraces (up to 30 nm wide) suitable for the study of
progression of chemical reactions on the surface. Two different treatments are
used to prepare the MgO substrates for deposition and they introduce
characteristic differences in film surface morphology. Thin films that are
grown on the phosphoric acid-treated substrates present reduced nucleation
density during the initial stages of film growth which results in long and wide
terraces. Due to the about 16 percent lattice mismatch in the Ni(001)/MgO(001)
system, film growth at 400C yields discontinuous films and a two-step growth
process is necessary to obtain a continuous layer. Ni films are deposited at
100C and subjected to a post-growth anneal at 300C for 2 hours to obtain a
smoother surface. The addition of just 5 wt. percent Crchanges the growth
processes and yields continuous films at 400C without de-wetting in contrast to
pure Ni films. With increasing Cr content, the films become progressively
smoother with wider terraces. Ni5Cr alloy thin films have an rms surface
roughness of 3.63+/-0.75 nm while Ni33Cr thin film is smoother with an rms
roughness of only 0.29 +/-0.13 nm. The changes in film growth initiated by
alloying with Cr are due to changes in the interfacial chemistry which
favorably alters the initial adsorption of the metal atoms on MgO surface and
suggests a reduction of the Ehrlich-Schwoebel barrier. The growth of smooth
Ni-Cr thin films with well-defined surface structure opens up a new pathway for
a wide range of surface science studies related to alloy performance.


title: Cyclically presented groups with length four positive relators

abstract:
  For cyclically presented groups $G = G_n(w)$ with positive length four
relators $w = x_0x_jx_kx_l$ in the free group with basis $x_0, x_1, \ldots,
x_{n-1}$, we classify finiteness and, modulo two unresolved cases, we classify
asphericity for the underlying presentations. We show that the fixed point
subgroup of the shift $x_i \mapsto x_{i+1}$ is always finite and we relate
finiteness of $G$ and asphericity to the dynamics of the shift action by the
cyclic group of order $n$ on the nonidentity elements of $G$.


title: Explicablility as Minimizing Distance from Expected Behavior

abstract:
  In order to have effective human-AI collaboration, it is necessary to address
how the AI agent's behavior is being perceived by the humans-in-the-loop. When
the agent's task plans are generated without such considerations, they may
often demonstrate inexplicable behavior from the human's point of view. This
problem may arise due to the human's partial or inaccurate understanding of the
agent's planning model. This may have serious implications from increased
cognitive load to more serious concerns of safety around a physical agent. In
this paper, we address this issue by modeling plan explicability as a function
of the distance between a plan that agent makes and the plan that human expects
it to make. We learn a regression model for mapping the plan distances to
explicability scores of plans and develop an anytime search algorithm that can
use this model as a heuristic to come up with progressively explicable plans.
We evaluate the effectiveness of our approach in a simulated autonomous car
domain and a physical robot domain.